August 23, 2017

Analysis of advantages of commonly used high precision carbide bits


In machining,hole processing accounts for about 1/5 of the total processing amount, and the holes in the hole account for about 30% of the whole hole processing.Compared with the traditional HSS twist drill, the current carbide bit is more and more users with such characteristics as high speed, long life and high precision.There are four main kinds of cemented carbide bits: solid carbide bits,indexable carbide indexable insert bit,welded carbide drill bits and replaceable cutter head carbide bits.Each kind of carbide drill has its advantages in special occasions.

Different types of carbide bit features

Integral cemented carbide drill bits (It can be processed with deep hole and high machining accuracy;Re-ground and reuse, effectively reduce the processing cost.

Carbide indexable insert bits (Discard blade, low cost, easy to change knives;Usually 2D - 6D specification with no centring function;the blade is rich ,The machining accuracy is relatively low.

Replaceable carbide drill bit type (centering function, complete kinds,same tool holder can be installed a variety of the diameter of the cutter c. high machining efficiency, high machining accuracy ,Many kinds of material of rotary cutter for different material,resharpening can further reduce the cost of the cutting tools)

Analysis of the advantages and disadvantages of these carbide bits

Drilling in high speed, high precision, many users choose the hard bit or replaceable carbide bits type, both the bit with the function of self-centering, and high efficiency, high precision drilling, drilling can generally IT6 - IT9 grades.In comparison with the two rigid ratios, the rigidity of the hard bit is better.

However, due to the high cost of considering the whole drill bits,in order to be able to re-grind many times,it is necessary to use a longer solid drill bit,which will weaken the rigidity.And replaceable tungsten carbide drill bitstype can choose the most suitable length of drill pipe,the greatest degree of assurance the rigidity, combined with the convenience of operation, the unit price of the cutting tools is harder than the drill unit price much lower, because of these factors, so more and more users like to use this kind of replaceable tungsten carbide drill bits type.


Because cemented carbide is very precious,use carbide bits correctly,accomplish the use of the material, it is every mechanical worker responsibility.How to use carbide bit correctly,mainly includes the following aspects:


1.Choose the right machine tool

Carbide drill bits can be used in nc machine tools,machining centers and other powerful and steel machine tools,and should ensure that the tip of the blade is beating TIR < 0.02.And the radial drilling, universal milling and other machine tools due to the low power,the spindle precision difference, easy to cause the carbide bit of the early collapse, which should be avoided.

2.Select the correct handle

The spring clamping, the side pressure handle, the hydraulic handle,the heat up the handle and so on can be used, but because the quick change drill clamping grip is not easy enough to cause the drill bit to slip and the failure, should put an end to use.

3.Proper cooling

(1) the cooling should be taken care of in the direction of the cooling,forming the upper and lower terraced configurations, and minimizing the Angle with the cutter as much as possible.

(2) the cold bit should pay attention to the pressure and flow, and prevent the leakage of coolant to affect the cooling effect.

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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.

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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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