August 18, 2017

Development of long-lasting anticorrosion technology by thermal spraying

 

In 1953,the American welding society of thermal spraying zinc and thermal spray aluminum in the industrial environment,water environment (not half submerged in flowing seawater and fully immersed in water to flow, and oceanic environment three categories of industrial test of 19 years, on the 4248 pieces of specimens, the test results show that the spray zinc,aluminum and closed coating can all of the above three types of environment of steel structures to provide long-term effective anti-corrosion protection,unveiled the world's most famous hot spraying 19 years AWSC2 14-74 test report.

American LAQUE 34 years anti-corrosion coating technology center in Marine atmosphere corrosion performance test report confirmed that the thermal spraying zinc and aluminum coating on a variety of harmful environmental medium and long-term effective, the United States on the basis of this combined with 19 years report, formulated the AWSC2 18-93 thermal spraying operation guide, as the thermal spraying construction enterprise quality control manual, in order to direct production.

The us navy's civil engineering laboratory has been tested for 10 years of Marine climate and sea water for 75 mu m thick spray zinc and aluminum coating,and no red rust has been found to prove that the coating is effective.

The French underground railway company has been exposed to zinc and aluminum for 10 years, and the results show that anti-corrosion is effective.

The former Soviet tbilisi underground mine water test pointed out that the spraying of zinc is at least 30 years of corrosion resistance.

The results are consistent across countries. Heat spraying zinc and aluminum coating can provide long-term and effective protection of steel in the Marine atmosphere, industrial atmosphere and seawater environment. These test results directly as standards based on the thermal spraying anti-corrosion technology,directly promoted the large steel Bridges since the 1960 s the world developed countries the application of thermal spraying anti-corrosion,for the world to make a huge contribution to the development of thermal spraying.

The application of thermal spraying in the bridge, has started in the 1930 s, the development to 60 ~ 70 s, Europe every year used in thermal spraying zinc wire up to 40 million pounds, the United States each year the thermal spraying zinc wire up to 2 million pounds;The corrosion resistance of general thermal spraying composite coating is 20 ~ 40 years.

Many Bridges in Britain have more than 25 years of zinc spray.Responsible for bridge maintenance engineers, according to their experience of large-scale structure spraying zinc that bridge in the bad environment, hard to get to the bridge or not likely to be close to, spraying zinc, aluminum is a kind of effective treatment methods. The UK has cited examples of the use of thermal spraying in large steel and steel Bridges across the country,all of which have been effective for more than 25 years without maintenance.

Koons ferri madden, reed fourth highway bridge,It is the world's largest steel bridge in the 70 s, 20000 t steel, spraying zinc wire 1 million pounds, anti-corrosion effect is very good, with over 20 years without maintenance.

South wales Newport (New port) George street Bridge (George Steet Bridge), founded in 1964, is located in the highly industrial pollution environment,using spray zinc corrosion,by 1985,namely after 21 years with no maintenance, check the coating in good condition,and confirmed that at least 5 years without maintenance.

Scotland's luxury linse feely (Qucesferry) fourth road bridge, built in 1960 ~ 1964, the bridge mainspan 1000 m, is located in the windy Marine environment, with spray zinc and closed processing, after 13 years without maintenance, found that coating color is still in good condition, structure and perfect.

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August 08, 2017

Several cases for grinding of carbide saw blade

Generally speaking,the carbide saw blade consists of two parts: saw board and cemented carbide saw blade. Hard alloy saw blade is basically exported at the moment. Fine alloy particles used in the blade thicker, larger, because that kind of alloy saw blade by grinding, frequently use full long, cemented carbide riveting quality also is very main,weld thin and well-balanced,as on the saw blade can accept bigger cutting force. The quality of saw blade is often the main one. As the saw blade is in the air, it will not only transmit the cutting force but also maintain the stability of the task. The quality saw blade not only has the dynamic amount of time and time and the accuracy, but also the static characteristics of it.

With corundum saw blades,on the other hand,when the saw blade cutting in succession, alloy saw blade cutting of heat will spread to sawing plate, reduce a measure of the sawing plate, excellent sawing plate under such conditions can also maintain the precision of the position, and poor quality of the saw blade sawing plate buckling will attack, reaction to the cutting precision.

Carbide saw blade as carbide cutting tools products is designed for cutting and grooving of metal material,It is the most commonly used cutting wood products processing, the quality of the carbide saw blade has close relationship with the quality of processed products.It is of great significance to use hard alloy saw blade correctly to improve product quality, shorten processing cycle and reduce processing cost.

If poor quality metal saw blades are selected, the following methods may be needed to repair them. So when is the carbide saw blade needed to grind?

 

In case of any of the following conditions, the carbide saw blade shall be repaired in time:

 

1) cutting quality no longer meets the requirements;

2) when the energy consumption of sawing machine is obviously increased;

3) the edges of the cutting materials have obvious detonation;

4) carbide saw blade wear reaches 0.2 mm grinding in time is very important, because the passivation of the saw blade edge at work,because the resistance increase, easy to cause a shaking of the saw blade,increasing the motor load,the saw blade and machine will cause damage.To continue cutting at passivation, each additional 10% of the cut will result in an additional 50% of the alloy damage. Shorten the service life of the saw blade.

Grinding of carbide saw blade:

 

1) it adopts precision, stable and non-vibrating sharpening machine, as well as suitable diamond grinding wheel, which can be repaired and used in accordance with the prescribed operating procedures to improve the service life of the saw blade. If the manual edge grinding equipment is used, the precise limit device and the end jump of the test tooth top are required.

2) remove the resin, debris and other debris from the saw blade before the grinding.

3) the cutting edge of the blade should be strictly followed by the original geometric design of the blade, and it is suggested that the cutting edge and back Angle of the blade should be used at the same time to increase the number of grinding times. Maximum service life.

For more information, please visit our website at wococarbide.com

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August 01, 2017

Specialization of cemented carbides and functionally graded structural materials

Cemented carbide as industrial teeth,which is mainly using plasticity and toughness to high hardness,high wear resistance metal compound performance and good high-temperature resistance and good bonding phase,to achieve the effect of cutting,drilling and abrasion resistance.These properties make it difficult for some of the properties of cemented carbides, such as hardness and strength, toughness and wear resistance,mainly because it is difficult to simultaneously increase the content of hard and bonded phases.Science and technology are the primary productive forces,and cemented carbidewith new structure can improve its hardness and toughness to a certain extent.The new structure mainly has gradient structure, nano and ultrafine crystal structure,ultra coarse crystal structure and other special grain distribution structure.

The cemented carbide with gradient structure refers to the gradient distribution of its hard and adhesive phases on a certain spatial scale,so that the regulation of its properties has the greatest degree of freedom.according to the performance requirements, there are many kinds of functionally graded cemented carbide.In 1980s,the development of functionally graded structures Sandvik rock drilling tools company's dual phase DP hard alloy generally show a structure similar to that of sandwich,the alloy in the outer layer and the middle layer of WC+Co phase organization,the inner WC+Co+ of three-phase microstructure. The content of Co in the outermost layer of the material is lower than the nominal cobalt content of the alloy, and has high hardness and wear resistance.The content of Co phase in the interlayer is higher than the nominal cobalt content of the alloy,and has good toughness and plasticity. The wear resistance and toughness of DP alloy are obviously better than that of standard cemented carbide.The technology is known as "the most important innovation in cemented carbide since 1950.".20 world 90s,this technology is applied to metal cutting bit, which greatly improves the life and cutting efficiency of the product.Another class of very important gradient structures cemented carbide is used for coated blade substrates.

The microstructure of cemented carbide inserts usually consists of WC,Co and beta phases. Beta phase is a brittle phase containing titanium,which can improve the hardness of the material,but reduce the toughness.There is a certain physical,chemical and mechanical incompatibility between the coating matrix and the coating.By controlling the sintering and heat treatment atmosphere, can form about 50um on the surface of cemented carbide free beta phase layer,with good toughness,and coating with high bonding strength,improve the toughness and anti collapse cutting life of blade coating greatly.The process is simple,and most cemented carbide coated blade substrates adopt this gradient structure.The research on functionally graded cemented carbide in China has been reported in 1990s,but it is still lack of systematic and deep elaboration.Because of the specialization of cemented carbide and functionally graded materials, more practical research is needed.

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July 27, 2017

Application of carbide cutting tools in automobile processing

How to optimize the drilling cycle without affecting the processing safety? Which processing strategy will shorten the cutting cycle by a second or two? These are the major challenges facing the auto industry.

How to deal with these challenges and the characteristics of drilling and threading processes in the automotive industry. Generally speaking, the materials used in the automobile industry are regular, mainly cast iron,carbide cutting tools,cast steel and forging.But the structure of the workpiece is extremely complicated, and the production efficiency, tolerances and surface quality of the workpiece are also very challenging.

If from these challenges,a series of turnkey tools are provided for the typical thread of the specific hole type and engine cylinder block, cylinder head, shell and crankshaft.

Dealing with complex car applications

460 - XM CoroDrill twist drill with 140 degrees point Angle, good centering function and smaller thrust, CoroDrill 460 - XM can provide excellent performance in many applications. The stability of tool life is beneficial to ensure reasonable inventory. Fine cemented carbide materials ensure a balance of hardness and toughness, good wear resistance and good service life. Two steps can be accomplished through a process that greatly benefits complex automotive applications.

Applicable to a wide range of applications

Diameter: 3-25mm (0.118-1.016-inch)

Drilling depth capacity: 8 times diameter

Internal cooling fluid and external coolant

Standard classification and carbide cutting tools

It is suitable for the large diameter drop hole which is required by the automobile industry

CoroDrill 400 straight flute drill with 120 degrees point Angle is optimized and is suitable for the complicated steps borehole diameter. Due to the support of the complex transitional form between the step holes, the drill can provide maximum performance when drilling the cylinder block and cylinder cover. Compared with the conventional spiral flute, the CoroDrill 400 is well suited to the machining of the step hole which is common in the automobile industry.

The CoroDrill 865 crankshaft oil hole drilling can provide an efficient solution for automobile iron parts and steel parts (especially crankshaft). CoroDrill 865 a series of characteristics, such as reduced apex Angle (more accurate centering), optimization of the Angle and first Angle characteristics (feed can be higher, chip removal more smoothly), increases the blade belt width (stability), update the spiral groove type (chip forming,carbide cutting tools strength higher) more effectively,make the production efficiency and tool life are improved.Adopting effective processing strategies and matching with controlled coolant or MQL is the key to ensuring success.

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July 12, 2017

Simple method for making tungsten drill bits on one’s own efforts

How do you find the proper carbide drill? Number of drilling machine parts for quenching far a matter, but often encountered in the work, such as: stamping die interrupt the socket head cap screw, or car rear plate spring and so on, it's about 45 HRC hardness, generally have difficulty in drilling bit out, and present the right carbide drill to buy less than, here introduces a simple method of self-made tungsten drill bits.

 

If less than 2 mm of carbide blade can be found,such as lathe operator with thin cut blade, if differences comfortable again,available general carbide insert the right to use the blade to cut thread cutting machine,and then press the appended drawings style of welding on the corresponding round bar, pipe's such as drill hole a little bit small,at least as large as the aperture. It can be used after manual roughing.If the diameter of the borehole is accurate, it can be used for grinding (tool grinding machine) and then grinding out the cutting geometry and chip groove by hand. And the drilling top Angle is slightly smaller than the normal bit, should be fixed with a small horizontal blade, make the hole easily hollow, prevent wobble. This type of drill can only be used for drilling hardened parts with deep holes. Socket head cap screw is broken in the hole, for example, bit diameter can be ground into a bit smaller than the bolt diameter is ok, such as drill M10 of screw, grinding to diameter Ø 7.8 ~ Ø 8. The maximum speed can be used when drilling holes. Just can't long time drilling,to keep back drill chip removal: drill pipe cooling appropriately, prevent oxygen welding the blade loss due to high temperature, the other main point can be reference to "hardened steel drilling are described.

In addition,tungsten drill bits is zero and negative front Angle, which is precisely the front Angle feature of hard alloy blade when cutting high strength materials and rough machining.

 

At present due to the evolution of cemented carbide manufacturing technology,fine grain of material to make the toughness of tungsten drill bitsis improved greatly, advanced coating technology makes the bit cutting performance is greatly improved, and the innovation of the cutting tool structure made up for the inadequacy of cemented carbide manufacturability is poor,which can produce large size and complex blade bit.

 

So in recent years, some famous foreign tool company, such as Walter, Kennametal, Sandvik, Seco has successively introduced all kinds of solid carbide drill bits, such as solid carbide drill bits, drilling of deep hole length to diameter ratio is as high as 70, it USES the XD technology, can be drilled in the process of deep hole without return, cooling through the cooling hole inside, and do not require any special cooling device), indexable insert carbide drill bit and removable nipple type products, such as covered with small diameter, large diameter and large length to diameter ratio, and other fields, due to its high efficiency, long life and high quality and a bit more than half a markets, especially in the production of some modern high degree online, traditional HSS twist drill has faded from people field of vision, gradually replaced by high productivity of cemented carbide drill.Therefore,tungsten drill bits are the trend of the future bit development.

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July 03, 2017

Research on cemented carbide end mills of Profile Based on its maintenance and selection

There are two main types of milling methods for carbide end mills' direction and rotation direction of milling cutter:
The first type is the milling,the rotation direction of the milling cutter and the cutting direction of the feed are the same, and the milling cutter holds the workpiece and cuts the final chip in the beginning of cutting.
Inverse milling,the second is the direction of rotation of the milling cutter and cutting feed direction is opposite,cutter before start cutting must be slipping a on the workpiece,start with cutting thickness is zero, the cutting at the end of the maximum cutting thickness.
When milling,the workpiece is pressed to the workbench by cutting force,and the workpiece is removed from the worktable during milling.Because of the best cutting effect of milling,it is usually preferred to milling,only when the machine has the problem of thread clearance and the problem of unsolved problem.
The cutting edge of carbide end mills should bear the impact load every time it enters the cutting.The load size depends on the cross section,workpiece material and cutting type of the chip. In the ideal condition, the diameter of the milling cutter should be larger than that of the workpiece, and the axis of the milling cutter should always be slightly away from the center line of the workpiece.When the cutter is placed in the cutting center, it can easily produce burrs. Cutting edge into the cutting and cutting out the direction of the radial cutting force will continue to change, machine tool spindle can vibration and damage, the blade may rupture and processing surface will be very rough, hard alloy cutter slightly off center, cutting force direction will no longer fluctuations, cutter will receive a pre load.
Maintenance of carbide milling cutter
When the axial line of carbide milling cutter or the edge line of the workpiece is superimposed or close to the edge of the workpiece, the situation will be serious,and the operator should do the relevant equipment maintenance work.
1. Check the power and rigidity of the machine to ensure that the required milling cutter diameter can be used on the machine tool.
2. The weight of the cutter in the spindle is as shortest as possible,reducing the impact of the milling cutter axis and the position of the workpiece on the impact load.
3. The suitable for the process of the correct cutter tooth pitch,to ensure that did not too much during the cutting blade mesh and artifacts caused by the vibration at the same time, on the other hand,in the narrow artifacts or milling milling cavity to ensure that there are enough blades and workpiece mesh.
Make sure to use every blade in order to get the correct cutting effect when the chip is thick enough to reduce the knife wear.The forward corner slot can be used to achieve a smooth cutting effect and minimum power.
5. Select the diameter of milling cutter suitable for workpiece width.
Choose the right major Angle.
Place the milling cutter correctly.
8. Use cutting fluid only if necessary.
Follow tool maintenance and maintenance rules and monitor tool wear.
The maintenance of carbide milling cutter can prolong tool life and improve work efficiency.
Choice of carbide milling cutter
Milling stainless steel in addition to the vertical milling cutter and cemented carbide end mills and the parts of the cutter material,the rest of the all kinds of milling cutter adopt high speed steel, especially high tungsten, molybdenum and vanadium high speed steel has a good effect, the tool life than W18Cr4V 1 ~ 2 times. The hard alloy plate for making stainless steel mill is YG8,YW2,813, 798, YS2T, YS30, YS25, etc.
The effect of spray cooling method is most obvious,which can increase the durability of milling cutter more than double. If the normal 10% emulsion cooling is used,the cutting fluid flow should be guaranteed to be fully cooled. When the carbide milling cutter is milling stainless steel, the Vc = 70 ~ 150m/min, Vf = 37.5 ~ 150mm/min, and it should be adjusted according to the alloy plate number and the different materials.
The adhesion of stainless steel and strong melting ability are easy to stick to the blade of the milling cutter,making the cutting condition deteriorate. In reverse milling, the blade starts to slide on the hardened surface, increasing the trend of working hardening.The impact and vibration of milling are larger, and the cutter blade is easy to be broken and worn.
When machining stainless steel, the cutting edge should be sharp and bear the impact. Can use the big spiral Angle cutter (cylindrical milling cutter, end mill), spiral Angle b increased from this, the tool life can be increased by more than 2 times, because work at the moment of the milling cutter rake Angle g0e by 11 ° increased to more than 27 °, milling fast. But b value should not be again big, especially the vertical milling cutter with b 35 ° or less advisable, so as to avoid weakening the blade.

For more details just visit our website at http://www.wococarbide.com/


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June 28, 2017

Carbide cutting tools are not widely used in production

The hard turning has been carried out by using carbide cutting tools. After more than ten years' development and popularization, this technology has gained great economic and social benefits. In the following, taking roll processing and other industries as an example, the application of superhard cutting tools in production is illustrated. Many large enterprises have used roll superhard tool of chilled cast iron and hardened steel roll and other types of vehicles, shortage of machining and fine turning, achieved good benefits:the average processing efficiency is improved from 2 to 6 times, saving processing time and power from 50% to 80%. Such as the Wuhan Iron and Steel Corporation HS60 to roll factory on the hardness of chilled cast iron roll rough turning, 80 semi refined car when the cutting speed is increased by 3 times, each car 1 rolls, saving power, labor costs more than 400 yuan,saving tool costs nearly one hundred yuan, achieved tremendous economic benefits. I like school with FD22 metal ceramic cutting tool HRC58 ~ 63 86CrMoV7 hardened steel roller (Vc=60m/min, f=0.2mm/r, ap=0.8mm), single blade continuous cutting roller path up to 15000m (tool flank wear width VBmax=0.2mm belt), to meet the requirements of the car instead of grinding.

At present, 70% - 80% of super - hard cutting tools have been used in domestic slurry pump factories. Slurry pump is widely used in mines, power and other industries. It is an urgent need at home and abroad, and its sheath and cover plate are HRC63 - 67 Cr15Mo3 high - hardness iron castings. In the past, it was difficult to make this material because of various cutting tools. Therefore, the process of annealing, softening,roughing, and then quenching must be adopted. After the use of ultra hard tools, a successful hardening has been achieved,eliminating annealing and quenching 2 processes, saving a lot of hours and power.

In automobile and tractor industry in the crankshaft, cam shaft, drive shaft processing, processing and maintenance tools, measuring equipment, processing problems often encountered hardened workpiece. If a vehicle factory in China, in the maintenance of the equipment required to process the bearing inner ring, the inner ring of the bearing (GCr15 steel) the hardness is HRC60, the inner diameter is f285mm, the grinding process, the grinding allowance is not uniform,2h can wear; and with super hard tools, only use 45min processing an inner ring.

After years of research and exploration,China has made great progress in carbide cutting tools, but the application of superhard cutting tools is still not widespread. The main reasons are as follows: production enterprises and operators do not know enough about the effect of using hard tools to make hard turning. It is generally believed that hard materials can only be grinded, and that the tool cost is too high. The first hard cutting tool cost than ordinary carbide cutting tools (such as high PCBN hard alloy is more than 10 times more expensive than ordinary), but its share in each part than the cost of grinding is low, and the benefits are much better than ordinary hard alloy;not enough research on the machining mechanism of superhard cutting tool;superhard cutting tool processing specification is not enough to guide the production practice.

Therefore, in addition to in-depth study on the machining mechanism of carbide cutting tools,we must also strengthen the training, the successful experience of demonstration of superhard cutting tool machining knowledge and strict operation regulations, the processing method of the high efficient, clean and more applied to actual production.

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June 22, 2017

The reasons why carbide saw blades are poor quality in China

China is the largest country in the world for carbide saw blades production,whereas saw declines in the prices, so many manufacturers because of low profits and discontinued collapse, while the foreign blade is quietly nearly 100 times the price to enter the market and sold well China.In my opinion, there are two reasons for the poor quality of China carbide saw blades.

Welding is very serious

We have investigated most manufacturers of tusngten carbide saw blades in China and found that the manufacturers of Chinese saw blades are trying hard to improve the quality of their products. The most noteworthy is the low quality China saw more than 80% manufacturers of the main problems in welding and plate, I have received the test sent over a domestic company, in a completely new circumstances, actually have a 30MM crack plate, if the blade is as high as 3000~8000 speed, completely may appear surprising results, not to mention what a good cutting effect: Welding fastness low, alloy brittle, alloy from oxidation, solder joints and other undesirable phenomena (welding method China above saw manufacture factory is currently using 80% current welding).

Another reason is that the Chinese people's own grinding machine is not accurate enough.

Chinese why companies do not want to buy imported advanced automatic welding equipment and grinding equipment? We found in China carbide saw blades mainly in the production of a large number of low cost advantages, mainly rely on exports to make operating companies in foreign countries are used in most low-end industries, most of its profits to foreign enterprises to earn. In order to change the quality of products, some enterprises in China have to sacrifice large amounts of money to buy fully automatic high-frequency welding equipment.Among them,5% of the enterprises have purchased fully automatic high-frequency welding equipment imported from Germany, and 5% of them have purchased fully automatic welding equipment in japan. The companies that bought fully automated equipment bought equipment and found that millions of dollars were not exported to foreign countries.The reason is that the quality of the imported high frequency welding equipment has been improved, but the output has not been improved, and the original advantages of Chinese enterprises have been lost. Coupled with the depreciation of machinery and export transportation costs after the product cost is very expensive, and overseas local production of alloy saw prices equally matched. Then, with China's manual high-frequency welding equipment, the same minimum cost, can produce more than 35 times the output of the saw blade. Obviously, China's products will soon dominate the market in the world. The Chinese don't have to spend a lot of money to buy foreign saw blades. For example, investing in a fully automatic high frequency welding equipment imported from abroad requires 700 thousand RMB, with a production capacity of 1200 sawtooth / h.Invest 700 thousand RMB to buy manual high-frequency welding equipment produced in China, the minimum output can also reach 42000 sawtooth / hour.

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June 21, 2017

What are the selection of various parameters of carbide saw blades?

Forcarbidesaw blades,to carry out the reasonable selection and collocation in order to better play its advantages,there is a very simple truth, saw blade tungsten carbidesaw blade manufacturing enterprises can not do so many specifications,according to the optimization principle and according to the current wood processing enterprises in the equipment, materials and other specific factors which currently used for tungsten carbidesaw blade the series of specifications.This will not only help us choose carbide saw blades,but also be beneficial to large-scale production of alloy saw blades manufacturers.

In general, sawing particleboard, MDF should be around teeth, sawing plywood, fireproof board generally choose ladder tooth (flat teeth, tooth combination).

Because the computer saws sawing rate,carbide saw blade diameter and thickness of the relatively large, about 350-450mm in diameter, 4.0-4.8mm in thickness, most of the ladder tooth, in order to reduce the edge collapse.

Sawing wood alloy saw blade, usually with inclined teeth around a, because this combination angle can be sharp, wood fiber cut, smooth incision.For the groove to maintain the bottom of the groove, you must use flat teeth, or use the left and right flat combination teeth.

Then, how do you grind thetungsten carbidecircular saw blades? Analysis of several important factors affecting the finish of the alloy saw blade.After reading this technical literature, remember the following 6 techniques, you can also wear a good saw blade.

Device saw blade

The first measurement of outer diameter of saw blade and the center hole, selected centering washers, then the blade mounted to the blade seat, then the knurled nuts saw seat lock, and then relax the blade seat locking screws, and move the saw blade base, the size of the outer diameter of the saw blade and the saw blade base scale corresponding alignment, then screw locking. If the blade has broken teeth or tooth, must use the guide disc. In general, using a relatively easy grinding grinding, should as far as possible the use of guide plate.

Rotation adjustment of circular saw blade

If the blade rotation without proper tightness, the forward displacement of the saw blade will not be allowed, so when the blade is installed in the left hand, the counterclockwise rotation of circular saw blades, the rotation of the elastic elastic,if improper,with M17 open wrench adjustment nut, the blade rotation of the elastic proper.The principle of tightness, in order to eliminate the inertia of the saw wheel rotation and the impact of the grinding wheel, can not be too tight.

Saw thickness adjustment

The center of the grinding wheel and the thickness of the saw blade should be in a straight line so that the grinding of the serration can be averaged up and down.

Cutting angle adjustment

Since the material to be cut is often changed, the appropriate cutting angle shall be selected according to the material of the cutting material. The method of adjusting the cutting angle is to loosen the clamping block screws first, then rotate the carbide saw blades seat base to the desired cutting angle, and then lock the clamping seat screws.

Tooth profile transformation

Generally, there are two kinds of teeth, one is triangular teeth, the other two are curvilinear teeth, and the teeth should be decided before grinding. Change the gear type should be in the machine running, with L plate hand change type change button, select the type of teeth to be grinding.

High-low tooth difference

Before grinding, you should decide whether to grind the high and low teeth. If you want to grind the high and low teeth, adjust the high and low gear adjustment lever to the required scale.

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June 14, 2017

The age of tungsten carbide drill bits is forthcoming

In the late 1980s, the main part of the drill used in all walks of life was a roll bit and a high speed steel drill.Of course, there are companies that are working on the "tungsten carbide drill bits". There was already a hard alloy bit on the market, but for technical reasons, it was limited to a large diameter bit. At that time, we have already foreseen the carbide path bit time must come, so only in a count of primary production is started development work in the corner. First, in order to make the drill bit, it must not be solder, it must be the integral bit. But, at that time, a lot of data need to manually calculate, for example, the ideal of groove shape design, shape of cutting edge design, etc., failure and repeated the test. In other words, it is now very common on the premise of data and the simulation of product development, at the time it is impossible, only by technical personnel's experience and feelings. After several years of development, the first bit of the "ZET1 bit" was born in 1987.

The quality of the carbide bit is good

It is important to note that, by the quality of tungsten carbide drill bits type and stratigraphic lithology, to speed up drilling speed and improve the single bit footage plays an important role. Drill more than a mouthful of oil and gas Wells typically use different size of the drill, the drill and the diameter of upper strata to use the drill bit, by bit drilling soft stratum, single bit footage, use the more time is short, a bit general reusable several Wells; In the lower strata of the drill, the smaller bit is used for the drill, and the drill is usually used with a bit of drill. The drill footage of a new drill bit depends mainly on the size of the drill, the type of the drill, the hardness of the formation and the fit of the drilling parameters. Generally speaking, the smaller the bit, the harder the ground, the less the footage. The larger the bit, the softer the ground, the more the drill bit.

At the time, about 70 percent of the market's customers were still using high speed steel drills, but we had confidence in the overall bit "ZET1 bit". Compared with the previous product, its processing efficiency is improved 5 times longer life expectancy, tools to 10 times, scraps discharge stability, excellent processing performance, can achieve a qualitative leap. However, the reality is the opposite of expectation, and the sales situation is not optimistic, for one reason is the price. Compared with the high speed steel drill, the price is about 30 times the price, and the product, which used to cost just 500 yen, now costs 15, 000 yen. Although the cost of each hole will eventually decline, and also can improve production efficiency, but the price is hard to let the customer accept the advantage of carbide bits  as a whole. Another reason is that the method and methods of using the whole drill are not known and must be trained from scratch. At that time, the introduction to use of the overall tungsten carbide drill bits no pause of machine tools, there are few customers and machine tool manufacturers also help us to use a method to the customer together. Many reported that some customers to use the method of high speed steel drill bit to use cemented carbide drill whole, result the collapse edge, so we to each customer to provide the detailed information. In addition, unlike the high speed steel bit, the drill is not considered to be ground again, so the combination of hard alloy tools also needs to be taught to the customer. The sales activities very to spend time with knowledge, but through these practical activities, finally will "ZET1 bit" in the auto industry as the center of the spread between the masses of customers. In retrospect, after the hard, finally won the customers for our understanding of the product advantages and praise, this kind of achievement feeling now I remember.

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June 09, 2017

The influence of material of wire drawing dies on the length of sizing tape

In order to form a lubricating coating thicker in the surface of steel wire, lubrication cone surface does not need to be polished, in order to increase lubrication pressure, work cone is crucial part of the core structure, forming wire surface lubrication layer and plastic deformation in this area, working efficiency of wire drawing dies also depends on the geometry and work cone area, it must ensure that the work cone angle of the machining accuracy and surface finish.The work should be processed into linear cone type,the surface shall not have arc transition or smooth transition, and the work cone angle and sizing zone should be kept in the same axis, die diameter and die diameter should be concentric,so that can prevent elliptic phenomenon in wire drawing. The sizing effect is to control the wire diameter, roundness, parameters of flatness and surface quality.

In order to ensure product quality, sizing surface needs to be polished, and the sizing and cone and outlet cone interface remain parallel to each other, and strictly control the sizing tolerance. The sizing length is decided by drawing materials and mold materials, but is mainly determined by drawing materials. In general, the high carbon steel, the bearing length is about 25% of the diameter of a 35%, for soft materials (copper), sizing zone length is generally 50% of the diameter of a 100%.

In addition towire drawing diesmaterials on the sizing zone length will also have a certain impact, the friction coefficient is relatively large, the sizing can be a little shorter; the friction coefficient is small, allowing the sizing is a little long, such as natural diamond die sizing is generally 35% of the diameter of wire drawing die a 50%. short sizing belt, under normal use, but not allowed to wear work cone, wear sizing, sizing with belt wear, sizing belt will gradually increase, overheating drawing, burning powder lubricant, lubricating failure, and can lead to transformation of wire rod surface but at low speed; drawing, length and diameter of wire drawing die material with the heat deformation can soften the lubrication powder, and fluid boundary lubrication formed on the surface of steel wire. So the bearing length should be selected according to the drawing material, mold material, lubricating powder and drawing The process was determined by experiments.

The exit cone tapered design is intended to strengthen the export of wire drawing dies,die to prevent crushing, exit cone requirements for polishing treatment, and sizing with mild and smooth transition at the junction of the exit cone, metal debris or wire may scratch the surface and produce a large amount of pollution when drawing, lubrication powder, and may lead to obstruction of a mold population, cause the failure of drawing lubrication in the future.

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June 02, 2017

Cutting utilization rate of cemented carbide inserts is widelt used in China

Cemented carbide inserts are more and more widely used in metal cutting machine industry, as is known to all, the hard alloy is an alloy material, and is more difficult to melt the hard compound metal, and metal bonding, and then through the manufacturing process of metallurgy. Therefore, the hardness of cemented carbide is not only high, but also has good wear resistance, toughness, patience and corrosion resistance. Especially the high hardness and wear resistance of carbide inserts is very practical, even at five hundred degrees of high temperature will not change, at one thousand degrees of temperature, hardness is still a lot. Cemented carbide blades are second only to diamond, and hard alloy blades have excellent bending strength, as well as impact toughness and corrosion resistance, which are common to alloy blades.

In the use of cemented carbide cutting tools together,to promote the circuit board needs cutting speed, not too hard or too quickly, otherwise the circuit board and the blade will collide, causing the blade damage, there may be serious accidents.

The prosperity and development of the socialist market economy is the best embodiment of keeping pace with the times. As one of the most hard cutting tools, cemented inserts is a powerful cutting tool in the production and processing industry.Cemented carbide,as the tooth of modern industry, has a strong promoting effect on the manufacturing industry.

Cemented carbide inserts, as a cutting tool of wealth, is the most effective processing tool in modern manufacturing industry, and plays an important role in promoting social and economic development.carbide inserts belongs to powder metallurgy industry. It is a kind of alloy material made of refractory metal hard compound and bonding metal by powder metallurgy process.Cemented carbide has a series of excellent properties such as high hardness, wear resistance, strength and toughness, heat resistance and corrosion resistance, especially its high hardness and wear resistance become the most important use. Chinese as hard alloy producer, is the world's manufacturing power, cutting of cemented carbide tool utilization rate is the most widely used, is the world's hard alloy cutting tools market share the most adequate positions, all countries are in the production of cemented carbide Chinese market as a long-term goal, this is both an opportunity and a challenge for us.

The requirement of economic globalization makes the increasingly fierce market competition show the obvious effect of survival of the fittest, and the development of cemented carbide blade market also needs to keep pace with the times and go on the front line of economic development. Chinese "12th Five-Year" planning has a significant guiding role to the social economy, especially on cemented carbide inserts, hard alloy tools using demand in front of the high-end equipment manufacturing industry, domestic cemented carbide blade performance advantages plus the times is more and more obvious,Chinese cemented carbide industry is going from production power to power production.

The rapid development of social economy is the economic globalization reflect the increasingly obvious, the biggest achievement is the reform and opening up with the times, hard alloy blade with the times is the inevitable direction of the development of the whole hard alloy industry, market competition is the most direct expression.

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May 31, 2017

Technological measures for preventing carbide inserts from grinding crack defects

Carbide inserts has high hardness,high brittleness, poor thermal conductivity, heat shrinkage rate, usually should be grinding with diamond grinding wheel with diamond grinding wheel. But the price is expensive, not easy to wear after repair, so many factories still use the ordinary grinding wheel for grinding.In the grinding process, the higher in hardness. Ordinary wheel, abrasive easily passivated, sharp blade surface friction to produce local high temperature, the formation of additional thermal stress caused by thermal deformation and cracks, directly affect the service life of the cutter and machining quality.Therefore,we should take the necessary measures to prevent grinding cracks. Through processing practice, summed up the technological measures the following can effectively prevent or reduce the grinding crack.

1.negative edge grinding method

Negative grinding method refers to a sharpening tool, first in the rake face or flank grinding out a negative edge. The hard alloy belongs to brittle materials, the grinding wheel vibration due to the cutting tool by impact load, prone to crack; at the same time, the instant heating and cooling the grinding zone the thermal stress may exceed the strength limit of cemented carbide and hot cracks. The negative edge grinding method can improve the strength ofcarbide inserts, blade to enhance anti vibration and impact load bearing capacity, and increase the heating area, to prevent the grinding heat large guide blade, so as to reduce or prevent cracks.

2.wheel with molybdenum infiltration

At room temperature, the powder and ethanol mixed solution made of molybdenum disulfide, then in a sealed container (to prevent evaporation of ethanol) will be the new ordinary wheel soaked in the mixed solution, removed after 14 hours, natural dry for 18 to 20 hours, the grinding wheel grinding wheel dry completely.By the treatment with internal voids of molybdenum disulfide the abrasive grains can lubricates the grinding wheel chip is good, is not easy to be blocked. The test proved that the grinding hard alloy blade with molybdenum wetted, sharp grinding, abrasive easily passivated, the deformation of the workpiece is small,smooth chip, chip shape with a band, take away most of the grinding heat. In order to improve the grinding effect, improve the blade yield.

3.reasonable selection of grinding parameters

If the excessive friction in the process of grinding, the grinding temperature can lead to a sharp rise, hard alloy blade is prone to burst, so the reasonable selection of grinding parameters is very important. The reasonable grinding parameters commonly used for circumferential speed of v=10 ~ 15m/min, =0.5 ~ 1.0m/min longitudinal feed f f =0.01 ~ 0.02mm/,horizontal stroke. Manual grinding. The longitudinal and transverse feed are not too large.

4.other technical measures

The knife rod rigidity tool holding spindle instability,beating can cause grinding cracks, therefore, by machine,grinding,machining system of fixture and tooling composition should have sufficient rigidity, and should control the grinding wheel axial and radial runout.

There are many factors caused by carbide inserts produce grinding crack,only choose the appropriate grinding wheel,the grinding process is reasonable,which can effectively avoid cracks, improve the grinding quality.

 

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May 27, 2017

Carbide dies as high-quality dies are developing towards high-end market

The cemented carbide dieshas basically been serialized and standardized. From the development of recent years, the research and design theory of cemented carbide die in China has been further, more scientific and more widely applied. Along with the rapid development of social economy and science and technology, with the tide of economic globalization, China on equipment manufacturing industry especially the high-end equipment manufacturing industry put forward new requirements, the development of high-end equipment manufacturing industry in China, the corresponding mold and the equipment manufacturing industry is closely connected to the standard industry, high-end hard alloy mould products market needs and requirements attendant. Industrial developed countries attach great importance to the development of standard parts for high-end cemented carbide die, especially high quality carbide mould standard parts. Mold standard parts can guarantee the quality of industrial products. As China's economy has entered a stable period, the gradual optimization of industrial structure, the quality of industrial products like requirements is also more and more high, this to the standard mold requirements are increasingly high, hard alloy mould China mold standard parts to the high-end market is the inevitable trend of development.

Cemented carbide dies is a very important alloy product. It can be used in many places, such as cutting tools, and it is also used in mining and road engineering. It has a very good hardness, and very wear-resistant, but in the process of use, there are many places to pay attention to. Before using the carbide die, read the relevant information in detail, and be proficient in the operation so as not to panic in case of an emergency. Secondly, in the process of normal operation of the machine, it is necessary to make good monitoring of the equipment status, and if it fails, it can be found and eliminated as soon as possible. It is also important to note that the operator should wear overalls and work caps to prevent accidents. In the process of machine operation, especially in the process of moving, you should pay attention to the surrounding environment, and avoid trees such as trees, wires and so on.

Uninterrupted operation of cemented carbide dies in practical applications often has a long time, so the equipment in use for a long period of time even after the failure should be suspended for a period of time, and do a good job of equipment inspection and maintenance work to ensure the normal operation of the machine.

Forming manufacturing technology and processing technology, mold manufacturing process of modern hard alloy has been very simplified,the standard mold parts, not only the accuracy, quality has been able to meet the requirements of assembly, and can purchase from the market, forming a blank, including forging, rolling template, can also purchase from the market.

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May 26, 2017

Pay attention to the details of using tungsten carbide blade

All factories have a collection point for scrap blades. There is no such thing as more interesting than the study of scrap blades,which leads to the formation of a pragmatic view of how carbide blades are used (and misused) and can be used to reduce costs.

The considerations should be the following easy to measure factors:

How many different types of blades are used?

What is the average number of cutting edges that a blade has?

What percentage of the cutting edges used in relation to the length of the cutting edge?

What are the number of worn, damaged or unused cutting edges?

The content of this article is based on the study of a large customer of a mountain tool. The results of this study represent a similar study conducted by our company.

Blade difference

The first fact to be determined is that the carbide blades used are very different. In our sample, there are 638 different blades to maintain the operation of six CNC lathes. The good side is that each blade is the champion of every category. But the 638 blades are packed in 10 boxes each, meaning 6380 stock blades. All this is just to keep the six lathes running. The next fact is that each blade has a relatively small number of cutting edges. In many workshops, the blade is still triangular or diamond. The possibility of the best combination of the number of cutting edges (triangular blades) and the cutting edge strength (diamond blade) provided by the convex triangular blade is clearly not enough to be recognized in many workshops.

In 1970s, the best advice would be to use a large, robust blade. The hard alloy used in that period was tough but not good enough. The strength of tungsten carbide blades is guaranteed by their size (large blade = thick blade = high strength blade). A blade requires that its cutting edge be at least three times longer than the cutting depth. Two things have changed at the same time. On the one hand, the average cutting depth for turning has been obviously reduced.

A study carried out by seco showed that the average cutting depth of turning about 2.5~3mm. on the other hand, the fourth generation of hard alloy today (such as TP2500) has very good toughness, but also its hardness (higher wear resistance). This means that for today's cemented carbide blades, the relationship between the length of the cutting edge and the depth of the cut can be radically changed. The geometry of the blade of the latest generation (for example, MF5) is clearly suited to the new situation.

Unused cutting edge

The situation becomes really clear when you look at the blade according to the way they wear in use. The correct form of cutting edge wear is the safety, predictable and controlled wear of the flank.The cutting edge should not break. The cutting edge is broken because of incorrect use or improper selection of the cutting edge. The cutting edge must be "worn" before being thrown into the box that holds the worn cutting edge. The new cutting edge, which has not yet been discarded for processing, is always striking.

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May 25, 2017

How to improve the durability of carbide turning tools

In addition to good tools, coated cutting fluids, there is a new process for cutting off the thermal circuit.

As everyone knows, in the process of metal cutting and chip deformation due to friction, so that the cutting area had a high temperature, at the same time as the tool and the workpiece of different materials, a thermocouple poles caused thermal electromotive force, the DC current heat. It is easy to strengthen the oxidation process of surface of carbide turning tool,and accelerate the tool wear. Under certain conditions,a thermal electromotive force is also generated in the contact area between the tool and the machine tool, the contact area between the workpiece and the machine tool,and the friction pairs of the machine tool itself. During the cutting process, there is also a thermal magnetic effect and an electromagnetic effect. In the high temperature contact zone,the surface will also produce electron emission of discharge phenomenon.

In recent years, domestic and international science and technology researchers show that the heat caused by thermoelectric current generated in the cutting process and other factors, the two heat current is to form a loop through the machine tool workpiece tool system. At the same time, there is a local thermal current in the tool - workpiece limited contact area cycle, and therefore exacerbated the tool wear. So, to improve the cutting performance and improve tool life in addition to the above basic way, can also adopt a new approach,and the strengthening of carbide tool wear thermal flow effect to fight, to cut off the hot current loop.

Cutting method of heat current circuit is very simple, even if the tool insulation and machine tool or workpiece and machine tool, the thermal current loop cannot be formed by cutting area, so as to reduce metal affinity,reduce bue and scale production,so as to improve the cutting performance of carbide turning tool, improve the tool life and processing quality.

How to cut off the thermal current loop. On the lathe, in the various carbide turning tool with a bakelite pad knife plate or plastic pad knife plate, the knife rod under the plane, and the side of machine tool carriage of insulation; milling, planer, if the vise clamping the workpiece,and the workpiece between jaw pad of wood or rubber the insulation board,workpiece and cutter and clamp the drill; it can be made of high strength plastic and plastic handle shank drill cutter, the shank and the spindle hole insulation.

It has been proved by practice that cutting off the heat current circuit is especially suitable for the processing of high strength, high hardness and hard cutting materials to show the effect, and the durability of the tool is usually increased by 1~2 times. Therefore, it is one of the easiest and easiest methods to implement.

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May 24, 2017

Systematic development of tungsten carbide cutting tools

Due to the high impact of high speed and high impact load on high speed milling,tungsten carbide cutting toolscan withstand the risk of breakage and fatigue at high speed. It turns out that in the case of repeated rotating load, 30% of the stress can cause the carbide to be damaged. So in high-speed cutting applications, the strength of the blades, the toughness and the resilience are the primary considerations. In addition, the high speed cutting tool material requirements: the blade surface quality and overall material of very low density of defects, and consistent with the subtle structural and fine grain size is the same important. Cutting material containing Cobalt (Cobalt) component of the higher, the greater the toughness and the fracture resistance of materials, the smaller the grain size, the higher the wear resistance, but in the process of cutting when the temperature increases, deformation resistance will be reduced. In the above tests, a typical tungsten carbide material is suitable for the application of aluminum materials for aerospace applications. A microstructure of a tungsten carbide type, WC -6co, shows the compact structure of uniform and fine grinding without alloy square particles. The uniform grain is about 1 mu m, and the hardness is analysed to 1630 HV30.

Crater wear, flank wear, the devolop tumor, edge defect and gap abrasion are the blades in the early failure of the main topic, and reduces the surface quality of workpiece materials. A surface polishing process called "mircrofinish", which USES a mirror (surface polished) blade, can reduce the wear and tear of the crescent, the edge defect and the debris tumor. The tool series did not use a special coating in the test,and all the tungsten carbide cutting toolswere carried out under uncoated conditions.

It has to be said that a revolutionary carbide blade design method has improved the quality of the structural components of the space industry and the surface surface of similar artifacts. By the blade, blade, blade axial ready-made tolerance,and in the process of cutting tool deformation produced by the deviation, can be used to the elliptical structure to a certain degree of compensation, and at the same time avoid the sharp edge of blade structure and formed by two milling knife pitch. (chip breaker with large positive rake Angle trough) and V groove design can make the cutting speed and feed the ascent to 7000 cubic centimeter clearance volume per minute, and maintain the good surface quality and smoothness. The design of the v-shaped slot allows the blade to withstand a strong centrifugal force, at a high speed of 40, 000 RPM. To achieve the reliable cutting process and the best surface finish, the additional factors such as the effect and vibration are also considered. Especially the analysis of the vibration, this is common in machining of tungsten carbide cutting toos and the spindle system of special natural resonance frequency excitation, increase the understanding of its technology application in the cutting tool performance and make a more correct guess. Light alloy aerospace applications thin-walled components, through the special design of carbide blade shape, selection of tungsten carbide and body set, make the processing application more effective, more productive, and at the same time to obtain a better surface quality. But in high performance (high quantity of chip removal) advances in the application of feeding and cutting speed, cutting tools, lathe spindle and manufacturers still faces from stability, the spindle design, process control system and security of each category of new challenge.

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May 22, 2017

Cold extrusion finishing with carbide turning tools

The size of the extrusion allowance determines the magnitude of the required extrusion force, and the magnitude of the extrusion force has a direct bearing on the extrusion effect.If the extrusion allowance is too large, the extrusion knife will wear rapidly, resulting in a lower surface quality; if the extrusion allowance is too small,it will not meet the expected processing goal. Therefore, the minimum extrusion allowance should be chosen as long as the extrusion accuracy is guaranteed. Generally, when extruding carbon steel and alloy steel material, the extrusion allowance can be selected from 0.025 to 0.04mm, and 0.03 to 0.05mm should be selected when squeezing the cast iron. When the workpiece material is soft (such as non-ferrous metal) can choose larger extrusion margin; workpiece size is small, should choose smaller extrusion margin, in order to prevent overall deformation. As the extrusion allowance is affected by extrusion, surface hardness, surface roughness of workpiece before extrusion and workpiece wall thickness, it is better to test extrusion before machining to determine the optimum extrusion parameters. High speed extrusion finishing can make extrusion cutter and workpiece surface contact zone temperature, workpiece surface yield strength decreased, the workpiece is easy to deformation and lower surface wave in the trough, thus improving the surface roughness of the workpiece. But if the extrusion speed is too high, it will destroy the lubricating oil film, which will easily cause burns or scratches on the surface of the workpiece. Therefore, there exists an optimum speed of light absorption (which can be obtained by experiment). When processing ferrous metal, the extrusion speed can be selected between 0.5 and 1m/ s, and the amount of the knife can be selected between 0.01 and 0.03mm/r. The bigger value is taken when machining the excircle, and the smaller value is selected when machining the inner hole. The following problems should be paid attention to in extrusion processfor carbide turning tools:

The working parts shall be the straight line of 3 to 5mm on the extrusion edge, and the tungsten carbide turning tools should be squeezed about 1mm higher than the center. Extrusion process should be adjusted according to the various phenomena produced by the workpiece surface. Such as the workpiece surface pitting or scratches, extrusion showed that blade surface roughness, burnishing speed; the surface peeling phenomenon indicates that the large amount of repeated extrusion, extrusion or workpiece material ductility. Lubrication and cooling in extrusion process are very important. Before extrusion workpiece surface does not allow the existence of rust, oil, iron, dust, lubricating and cooling fluid should be injected into the full extrusion process, to take the heat generated in the extrusion, prolong the service life of extrusion knife. Usually, the mixture of oleic acid and kerosene can be used to squeeze the cast iron. When it is used to squeeze carbon steel and alloy steel, oil can be used as a cooling lubricant.

The extrusion test and the processing practice show that the cold extrusion finishing of the workpiece with carbide turning toolson the surface has the advantages of reliable quality, simple operation, economical and practical, high efficiency and low cost. Before extrusion workpiece surface roughness is Ra3.2 ~ 1.6 m after extrusion surface roughness is Ra0.8 ~ 0.2 m, improve the rate of up to 70% ~ 90%; by extrusion can also reduce the size of the workpiece diameter tolerances; extruding after burnishing hardening layer of workpiece is 3mm, which can greatly improve the fatigue strength of the workpiece and anti corrosion ability. If the extrusion knife is mounted on a vertical lathe, extrusion of the oversize workpiece beyond the grinding range of the grinding machine can be carried out. The extrusion processing method has wide application range, and can be used for processing ferrous metal materials and processing non-ferrous metal materials.

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May 19, 2017

discusses how to select thermal spray materials for coating

 

Thermal sprayingis a series of process,in the process, fine and dispersed metal or non metal coating material in a molten or semi molten state, deposition to a substrate surface after preparation, forming a spray deposition layer. The coating material can be powdered, banded, filamentous or rod-shaped heat. Spray gun from fuel gas, arc or plasma arc with the necessary heat, the thermal spraying material is heated to a plastic state or molten state, and then subjected to acceleration of compressed air, the constrained particle beam impact onto the substrate surface. The impact to the surface of the particles, and the deformation by stamping, forming a laminate sheet. The adhesion after substrate surface preparation, then cooled and piled up, eventually forming a layered coating. The coating for different coating materials can realize high-temperature corrosion resistance, abrasion resistance, heat insulation, anti electromagnetic wave function.

The correct choice of thermal spray coatingmaterial is the key to ensure the work required for the properties of the coating. The coating materials selection, should first consider the working conditions and performance of workpiece coating required, but also consider the workpiece material, batch, economy and intends to adopt the method of thermal spraying coating. According to the function of the coating can be divided as the corrosion resistant coating, abrasion resistant coatings, friction reducing and sealing coating,high temperature resistant thermal barrier coatings, insulation or conductive coating, the size of repair coating.

The surface of the workpiece after coating in the rejection caused by failure reason is often not a single factor, so can meet the requirements of working conditions and performance of the coating does not necessarily exist simple relationship should be analyzed in detail. According to the working conditions,and reference and experimental data on the coating structure, physical, chemical, mechanical and other comprehensive performance consider, in order to determine one or several kinds of coating materials.

Wear resistant coating is one of the main fields of the application of surface coating technology. Although there is a general relation between the hardness and wear resistance, hardness and wear resistance but not entirely representative of the surface coating. Because of the different types of wear properties of material is not the same, and in the wear and often accompanied by shock, corrosion influence of fatigue, and temperature.

The choice of surface coating materials can not blindly pursue high performance or high price of the coating material, resulting in unnecessary waste of material price can not be used as selection of thermal spray coating quality standards, in order to meet the working conditions of reaction requirements, as far as possible the use of cheap coating materials, is particularly important in mass production when for example, can use the material of Ni based alloy coating without cobalt base alloy coating materials.

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May 18, 2017

market prospects of ungsten carbide powder is better off, steady and strong

A sound and effective market regulation mechanism and indirect regulation of tungsten industry policy will be conducive to environmental protection. To increase the production specification mining tungsten supply gap makes most of tungsten concentrate holding the goods cover Xishou mentality increasingly strong, tungsten concentrate prices high stalemate.

Downstream of the tungsten carbide alloy from the market performance in general, enterprises and products factory new orders is not much, but the cost is behind the leading price; tungsten materials market turnover flat. The price of tungsten carbide powderdespite a slight boost, but the downstream demand is not increased significantly, the market transactions to complete pre orders for the Lord, so the short-term market will be stable in tungsten carbide powderstrong. Indicates that the tungsten market will toward healthy and stable direction, the market will follow in the footsteps of tungsten carbide powder, the prospects for the better.

tungsten carbide powderwith tungsten oxide as raw materials, reduction with hydrogen in four tube muffle furnace or multi furnace, particle size from 0.6-30 microns. The main points of coarse, fine granularity, few, silver powder, impurity content based on the national standard.

Made by hydrogen reduction of tungsten trioxide or ammonium paratungstate. Prepared by hydrogen reduction process of tungsten carbide powderwas generally divided into two stages: the first stage in the 500 ~ 700oC temperature, were reduced to two tungsten oxide; second stage in the 700 ~ 900oC temperature, two tungsten oxide also into tungsten carbide powder. Redox reactions often in tubular furnace or rotary furnace.

The performance reduction of tungsten carbide powder(such as purity, particle size, particle size etc.) depends mainly on the reduction process. The reduction of tungsten carbide powderin tube furnace, the main parameters affecting the reduction rate is reducing temperature, loading amount of tungsten oxide in burning boat, boat speed, the water content in hydrogen flow and hydrogen gas. With the increase of reduction temperature, the particle size of tungsten carbide powderbecame thick.

Preparation of tungsten carbide powderin hydrogen reduction method, and early used tungsten oxide carbon reduction method, tungsten carbide powderpurity reduction temperature is higher than the 1050oC. obtained by this method is low. In addition, using aluminum, calcium, zinc and other working process of tungsten oxide is in progress. For the special use and high requirement purity, ultra fine grained tungsten carbide powder, tungsten chloride is the development of the hydrogen reduction of tungsten carbide powdersize to be less than 0.05 M.

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