In the powder coating, coating curing bad reasons have two aspects, one is the formula design of powder coating is not reasonable, coating performance can not meet the requirements, the second is the performance of powder coating itself is no problem, but in the powder coating, coating process control is not reasonable, resulting in coating performance failed to reach technical indicators.

From the perspective of powder spraying, if the match between resin and curing agent is not reasonable in the formulation design, such as the selection of resin reactivity or the selection of curing agent varieties and dosage is not reasonable; Packing mass percentage or volume concentration is too large these problems will affect the physical and mechanical properties of the film.

From the perspective of powder coating process, there are several reasons that affect the curing of coating materials.

(1) the baking temperature of the baking oven fails to reach the baking temperature required by  spraying powder. While baking furnace temperature control can meet the design temperature or when no load required by the powder coating baking temperature, but the full load cases, caused by a lack of the total quantity of heat, sometimes can not meet the design temperature or powder coating the baking temperature, the temperature is low, particularly the northern region winter workshop if baking furnace heat preservation condition is poor, be before coating in baking furnace and lower temperature, by coating material thickness and thermal capacity is big, it is easier to appear this kind of problem. This problem is more likely to occur when the temperature of the baking oven cannot reach the curing temperature of the powder coating. When the temperature of baking oven cannot reach the curing temperature of powder coating, on the one hand, it can be solved by increasing the heating power; On the other hand, it can be solved by extending curing time and other measures.

(2) in the baking oven, the baking curing time cannot reach the baking time required by the powder coating. In the baking condition of powder coating, baking time refers to the baking time calculated after the coating reaches the baking temperature, rather than the time calculated after the coating is put into the baking oven. The thicker the coating material, the more hanging pieces, then the heat capacity of the coating is also greater, the coating temperature to control the temperature of the time it takes longer. In a certain length of baking oven, the effective baking time is shorter when the velocity of conveyor chain is constant. If the effective baking time is not enough, coating curing is not complete, coating physical and mechanical properties can not meet the requirements. Therefore, in the powder coating, it is best to use the furnace temperature tracking instrument to determine the temperature change of the coated material in the baking oven under full load condition, in order to determine a reasonable baking curing temperature and time, so as to ensure the complete curing of the coating film, but also to ensure the physical and mechanical properties of the coating film.

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Tungsten carbidecutting tools are often used to process refractory materials. The wear resistance and machining performance of hard alloy cutting tools can be improved by the surface texturing technology. As a fast non-contact automatic machining technology, laser machining can produce microstructures on the surface of cemented carbide tools. In this paper, the influence of the average power, scanning speed, pulse frequency, defocusing amount and scanning times on the microstructural size and morphology of cemented carbide cutting tools is studied, so as to select the optimal laser processing parameters. The experimental results show that the depth and width of the micro-groove increase with the increase of the average power, but the excessive power leads to severe ablation and uneven bottom side morphology. The increase of scanning speed and pulse frequency will make the depth and width of the micro groove decrease. The too large scanning speed will make the bottom surface discontinuous. With the increase of pulse frequency and scanning frequency, the bottom surface of the groove becomes flat. Defocusing goes from 0mm to negative 1. At 2mm, the width of the micro-groove slowly increases, while the depth first increases and then decreases, and the bottom surface morphology changes from continuous to sparse holes. By optimizing the technological parameters of the hard alloy cutting tool for laser machining, the fine single and mixed microstructures of the cutting tool surface were prepared.

For coating woodworking tool wear characteristics, through the coating cemented carbide cutting tool cutting in cocobolo test, with the help of scanning electron microscope and energy spectrometer, tool wear surface observation analysis, to study during the turning processing/toe cocobolo workpiece of different processing parameters on the coating cemented carbide tool wear. According to the test results available: with the increase of cutting speed on each floor, cutter knife after the surface wear is also increased; However, with the increase of cutting distance, the influence of different outer cutting feed speed and molding cutting feed speed on the wear on the cutting surface after cutting tool gradually decreases. Under the same processing parameters, the sequence of coating peeling of the tool is tin-al2 with the increase of cutting distance O3 - TiC, until coating spalling, completely exposed substrate and coating failure in the end. In the process of cutting tool coating failure, often accompanied by flake coating falls off phenomenon. After coating complete failure, main produce tool matrix and workpiece oxidation wear and adhesion wear. Therefore, when turning processing wooden crafts, selecting rational Angle of the structure of the cutting tools, setting reasonable processing parameters, not only can improve the machining efficiency, also can improve the service life of the cutting tool.

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In the production of steel wire, the consumption oftungsten carbidedrawing diesarebroken and worn. Broken molds can only be scrapped, worn molds can be repaired and reused, so the proportion of broken molds should be reduced as far as possible in production.

According to statistics, the form of core failure is:

(1) longitudinal crack, 75% of the broken mold is longitudinal crack, 90% of which is normal damage caused by the thinning of mold core wall after repeated grinding, only a small part is caused by excessive drawing surface reduction rate, dirty cleaning of steel wire surface oxide skin, bad coating and bad mold mounting;

(2) transverse crack, which accounts for about 13% of the total, is mainly caused by bad mold setting, such as excessive taper or non-roundness of the mold core and poor contact between the mold core and the bottom surface of the mold cover. Drawing surface reduction rate is too large, poor lubrication is the secondary cause;

(3) crack and outlet end meat broken

Crack accounted for 6%, mold material defects and improper wire drawing process accounted for half, meat is mainly mold quality problems.

Die hole wear has three forms:

(1) rough surface.

The deformation heat caused bytungsten carbide wire drawingdiescauses the temperature of the mold to rise, and the oxidation color appears locally, causing slight wear. Poor lubrication results in spot-like welding between steel wire and die hole surface, loose and displacements of tungsten carbide particles, scratches and ripples, rough surface of working cone and diameter belt, and large wear.

(2) the ellipse.

The hardness of hard alloy is not uniform, the drawing direction does not coincide with the axis of the die hole, and the single side of the die hole is subjected to force, resulting in ellipse.

(3) annular groove. It is a typical fatigue wear. In the process of wire-drawing, the die hole continuously bears the impact of the wire material, which loosens and falls off the tungsten carbide particles and forms a rough surface. The rough surface scrapes off the metal scraps from the surface of the steel wire, which worsens the lubrication conditions and accelerates the wear rate.

From oxidation discoloration to surface roughness to the appearance of annular grooves is the process of increasing wear. The way to use the mould reasonably and extend its life is to wear it in time and change the mould before the annular groove appears in the mould hole. The mold should be cleaned and checked in time after each use. If the surface is slightly worn, it can be used as the process mold by direct polishing or fine grinding and polishing. The grinding amount of the mold should be controlled at the minimum level as far as possible, and the number of times of repair and reuse of the mold should be increased. According to GB/T 61 10 regulation, when the die hole diameter is close to the size of the die blank maximum aperture, more attention should be paid to check the die hole surface, even if there are slight lines to scrap, to prevent the waste steel wire. Die life is usually 0. When 01mm pull out the number of meters or quality of the steel wire to measure, pull medium specification (diameter 4.0mm) special steel wire, the life value of the hard alloy die generally can reach 300,000 m / 0. 01 mm and above. Die consumption is usually expressed by the amount of hard alloy die core mass consumed per ton of steel wire, and the die consumption index of special steel wire is about 150 -- 250 g/t.

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Nanometer W and WC powders prepared from raw materials with different morphologies and structures all present different degrees of genetic characteristics of morphology and structure. The fine yellow tungsten particles obtained by high-power ball grinding grading treatment are small and loose in morphology and structure, making it easier to prepare nanometer W and WC powders with relatively loose structure and good dispersion.

Ultrafine tungsten carbide powderpellet characteristics and its influence on the abnormal growth of cemented carbide grain. The other batch of powder size distribution is uniform, with few aggregates. Two batches of tungsten powder were carbonized under the same conditions to prepare ultrafine tungsten carbide, and ultrafine cemented carbides of the same brand were prepared separately. The results show that tungsten carbide pellets inherit the basic characteristics of tungsten powder pellets, and the carbonization process will densify the pellets. Wet-grinding process can completely break and disperse the pellets of tungsten carbide, but a large number of nanoparticles with high activity, incomplete crystallization and serious defects will be generated, reducing the uniformity of the powder. The abnormal growth of superfine cemented carbide grain is directly related to the grain size of tungsten carbide.

Casting tungsten carbide powders with different preparation methods and particle sizes were added to fe-base alloy powder. The microstructure, phase composition and microhardness of alloyed layer were analyzed by metallographic microscope, SEM, XRD and durometer. The wear - resistant performance at room temperature was tested by wheel wear tester and compared. The results show that the cladding layer is mainly composed of leytenite, and the preparation method and particle size difference of tungsten carbide powder have important influence on the wear resistance of the composite. Tungsten carbide powder prepared by plasma rotating electrode atomization has the best wear-enhancing effect.

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Now is the time when cemented carbide is the main material of cemented carbide cutting tools. Compared with high-speed steel, cemented carbide has better performance and higher cutting efficiency. It is the most important guarantee of high efficiency of modern cutting technology together with super-hard cemented carbide cutting tools. At present, the proportion of cemented carbide cutting tools in China is about 40%, far lower than the level of industrial developed countries, restricting the overall level of China's cemented carbide cutting tools. Without good carbide tool materials, any carbide tool innovation and cutting progress are lack of the necessary material basis, can only be a castle in the air. To fundamentally solve the problem, however, involves the adjustment of industry structure, to speed up with hard alloy materials and carbide cutting tools production base for research and development ability of the construction process, increase rapidly carbide carbide cutting tools in the proportion of all carbide cutting tools. This is an expensive project, which needs the support and operation of the government departments concerned.

The innovation momentum ofcemented carbide toolstructure is very strong, and the new cemented carbide tool structure introduced by various cemented carbide tool companies has become the highlight of the machine tool exhibition in recent years. Innovative cemented carbide tool structure not only improves the performance of cemented carbide tools, but also has a great impact on the development of cemented carbide tools. Such as the slope milling cutter structure, greatly expanded the function of the milling cutter, also reduce the time for changing the cutter, its structural characteristics have been promoted to different types of milling carbide cutter, the formation of a variety of milling cutter can slope milling, promote the development of milling processing technology and milling cutter. And such as large feed small cutting deep milling cutter, not equal spiral Angle vibration elimination end milling cutter, including glazing cutting blade, blade bottom with guide rail with thread turning tool and copying cutting tool, carbide tool inside cooling structure and so on, too numerous to enumerate. Every new cemented carbide cutting tool on the emergence of the attention of the industry, and quickly in the industry is promoted, to develop varieties of cemented carbide cutting tools to improve the performance of cemented carbide cutting tools play a great role. China's many cemented carbide cutting tool enterprises, only do cemented carbide cutting tools do not produce cemented carbide cutting material, should pay more attention to the innovation of cemented carbide cutting tool structure.

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Bulk amorphous alloys (BMGs) have high strength, hardness and elastic deformation. These characteristics greatly improve the wear resistance of amorphous alloys. So amorphous alloys attract more and more attention in the field of wear resistance. Among them, fe-base amorphous alloy has been a hot spot in academic research and industrial application because of its low cost. However, bulk amorphous alloys have high brittleness at room temperature, and it is difficult to prepare large-scale amorphous alloys, which limits their wide application. In view of this, many researchers try to prepare amorphous coatings on crystalline substrate surface. The amorphous coating can not only inherit the high hardness and wear resistance of bulk amorphous alloy, but also solve the room temperature brittleness and size limitation. At present, thermal spray coating is the most popular technique to prepare amorphous coatings, especially plasma spraying and supersonic flame spraying. QIAO et al. prepared amorphous Fe Cr MoCSiCoAlY coating by plasma spraying, and found that the coating hardness was HV0.1884±61, and the wear resistance was better. JIANG et al. prepared Fe74Cr7Mo3Ni3Si2BP6C4 amorphous coating by plasma spraying, and found that the porosity of the coating decreased with the increase of Mo content.

Surface engineering technology is an important part of advanced manufacturing technology and also provides important technical support for manufacturing technology innovation. Surface technology on the surface of material surface protection, restoration and surface modification has distinctive advantages, such as thermal spraying technology is a kind of surface technology, with the continuous development of coating technology and coating materials, thermal spraying coating for its better than that of base material, expand the application range of materials, improve the service life of the parts, save the resources. In this paper, based on the actual parts on the surface of the insulation, wear resistance and impact resistance, thermal spraying technology was studied, the thermal spraying material and related auxiliary craft, with 45 steel as substrate material, choose the micron grade respectively Al_2O_3 ceramic powder and nylon 11 powder as the coating material, the explosion spraying process method, on the 45 steel substrate material specimen Al_2O_3 ceramic coatings, reunion Al_2O_3 ceramic coating was prepared, in addition, the preparation of nylon 11 bythermal spraying coating. The surface morphology, structure and particle size of the coating were examined by metallographic microscope. The phase structure of Al_2O_3 ceramic coating was determined by X-ray diffraction, and the crystallinity of nylon 11 coating was calculated.

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Coated carbide cutting tool is the most important cutting tool in the world, because of the coating and the carbide matrix composition difference is too big, the waste coating carbide in the recycling process needs to be stripped of the coating. In this paper, different grades of carbide spray coatings were used as experimental materials, and the peeling of their surface coatings was studied by different methods. The surface morphology, chemical composition, structure and properties of the samples were analyzed by using 3D high field depth microscope, scanning electron microscope, EDS, EDX, XRD and microhardness tester. The results show that:

1) the TiN coating on the surface of waste cemented carbide can be completely removed by using the alkaline solution of potassium oxalate and hydrogen peroxide. The optimal ratio of the solution is K2C2O4(0.5mol/L), H2O2(3mol/L) and PH=13. There are three kinds of corrosion, including spot corrosion, crevice corrosion and uniform corrosion. Pitting corrosion and crevice corrosion are caused by pitting, crevice and other defects of TiN coating. During TiN coating stripping, uniform corrosion is the main method. After TiN coating stripping, nitrogen exists in the form of NH3 or ammonia, and titanium dissolves in the solution in the form of TiO(C2O4)22.

2) the TiN/ alpha-al2o3 /TiCN coating can be effectively removed by the mixed molten solution of sodium hydroxide and sodium carbonate. The best coating removal effect can be obtained by the molten salt method under the conditions of 700 degrees and 40 min, but the damage to the substrate is large, and the quality loss rate of the sample is up to 3.32%. Alpha -Al2O3 coating is removed mainly by reaction with sodium hydroxide solution.

3) the multi-component composite carbide spray coatings containing A1203 can be quickly and efficiently peeled off by physical pretreatment and independently developed coating stripping solution. In the process of dissolution method, the pretreatment method has a great influence on the rate, effect and morphology of the hard alloy matrix. In the process of high temperature treatment, the coatings of TiN and Ti(C, N) with low oxidation temperature crack and form a large number of grid-like micro-cracks. The loose oxidation layer rapidly reduces the hardness and reduces the bonding strength between the coating and the substrate. Sandblasting process destroys the coating structure, causing bulges, cracks and holes in the coating, reducing the adhesion between the coating and the substrate, and speeding up the peeling rate of the coating. The best pretreatment method of the dissolution method is the high temperature treatment of 450 degrees for 90 min, and the cooling method is air cooling. Under this pretreatment method, the coating can be completely removed after the sample reacts in the stripping solution for 24 h, and the mass loss rate is about 1%.

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Wear is a variety of mechanical parts in the working process of one of the main failure forms. Statistics show that in the failure of mechanical parts, about 75% ~ 80% belongs to metal wear, provide machine is about 30% ~ 40% of energy consumption on the friction and wear in the process, and most of the failure phenomena occurred in the material surface, and take various means to improve the surface performance of materials, to enhance the safety and reliability of the parts or to extend the service life is very effective. Cemented carbide as a set of high hardness and toughness is higher than the one of a material, industry often apply it to require the surface damage resistance and abrasion resistance of high places, however The whole of the workpiece using hard alloy will greatly increase the cost, and the requirements of higher than its hardness of the tool, limiting its range of application.

If we can, therefore, in the preparation of low carbon steel surface layer of the cheap kind of tungsten carbide spray coating, make its have the cemented carbide surface performance, in order to improve the service life of the under some special conditions, can reduce the cost, and will be of great technical value and economic significance and broad application prospects. The preparation and properties of WC cemented carbide coating is cemented carbide and hot hardness is the highest, and Co, N I, Fe of metals such as good wettability, especially cobalt. When the temperature rises to more than metal melting, WC can dissolve in the metallic melts.

Introduction arc spraying is a process in which molten metal wire is atomized by high-speed air stream and sprayed onto the surface of workpiece to form a coating by using arc as heat source. Powder composite arc spraying technology is developed on the basis of arc spraying. It is a process of melting wires by arc and adding alloy ceramic powder to the metal surface at high speed to obtain the composite tungsten carbide spray coating with high wear resistance and corrosion resistance. This method can be used for the parts and components made of carbon steel, alloy steel, cast iron, etc. The method can also be used for surface repair of some worn parts or corroded parts. In recent years, arc spraying technology develops rapidly and is widely used in various fields of industry. In this paper, the microstructure of powder composite arc spraying coating and common arc spraying coating are analyzed, the microhardness of coating and substrate are tested, and the wear resistance of the two coatings is compared.

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Ultrasonic machining diamond die has long been used in the domestic application, but used in the hard alloy drawing die processing at present few, especially the larger aperture drawing die is so. Ultrasonic grinding is the transformation of electrical energy into mechanical energy at a frequency of about 20,000 cycles per second (20,000 times per second for longitudinal movement); Speed movement processing equipment. At present, complicated softbank welding device is used in the connection of copying needle and changing pole, otherwise the processing efficiency will be greatly reduced. Due to the processing speed, if the cemented carbide drawing die processing, according to the requirements of process strictly every processing a wire-drawing die need to replace a needle, the atmosphere day frequently change requires a lot of needle, the needle and complex welding must be conducted, it is seriously hampering the this technology in the application oftungsten carbide wire drawing dies to touch. In addition, because the processing speed is fast, difficult to master, not easy to achieve linear processing, and high concentration of energy and other factors, therefore, in the promotion and use is also limited.

Compared with hard alloy die, polycrystalline diamond die drawing die has the following obvious advantages:

1. High drawing efficiency

In the process of using the drawing die, necessary maintenance is very important to the service life of the drawing die and the surface quality of wires. It is usually recommended that customers maintain the polycrystalline diamond drawing die every 24 hours. Within 24 hours, the diameter change of polycrystalline diamond wire drawing die is small, and the rate of wire diameter change of pulled wire is also small. For the whole production process, the compression rate of wire diameter of each drawing die is relatively stable, and the ratio of input and output is large.

2. Good wear resistance and long service life

The drawing die life of polycrystalline diamond is about 30-50 times that of the hard alloy die, so it is not necessary to stop the machine often to replace the die in the drawing process. The aperture of polycrystallinetungsten carbidewire drawing dieschanges very little in unit time, and the size of wire pulled out changes very little, which is very beneficial to the winding of reel wire. Generally, the winding number of wires pulled out is fixed. If the finished size of wires becomes larger soon, the winding number will decrease relatively quickly, which requires constant changes in the size of the reel, which is not conducive to the improvement of production efficiency.

Save on raw materials

If the wire coated with metal on the drawing surface is stopped during the drawing process, the electroplating process does not stop, which will lead to the excessive plating thickness of the wire surface that is being electroplated, and the wire shall be cut off when the drawing starts again, resulting in great waste. The more times the machine stops, the greater the waste will be. Using polycrystalline diamond mold, this waste can be greatly reduced.

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The additives in cutting fluid can promote the leaching of tungsten carbide in carbide cutting tools. Tungsten carbide leaching not only reduces the tool life, causes the waste of resources, but also causes asthma, pulmonary fibrosis and allergic dermatitis. Aimed at cutting process, carbide cutting tools in the phenomenon that the tungsten carbide leaching screening of some commonly used in water base cutting fluid and organic additives, inorganic additives they are investigated respectively the influence law of cemented carbide tungsten carbide in the leaching, leaching mechanism, and synthesis effective inhibitors prevent oxidation dissolution of tungsten carbide carbide cutting tools. The results of immersion test of cemented carbide blade in aqueous solution show that some corrosion pits appear on the surface of the blade after immersion in distilled water. When sodium carbonate solution is added, the alkalinity of aqueous solution decreases and tungsten carbide leaching on blade surface becomes more serious. The above phenomena indicate that tungsten carbide in carbide blades will oxidize to form tungsten trioxide in aqueous solution. When sodium carbonate is added, tungsten trioxide generates its own complex anion tungstate in sodium carbonate solution, which aggravates tungsten leaching due to its high ionization potential and good ability to attract ligands. In order to effectively inhibit the leaching of tungsten carbide on the surface of carbide cutter, the effects of different additives in cutting fluid on the leaching of tungsten carbide were studied.

In the production and cutting process of carbide tools, in order to protect carbide tools, cutting fluid will be used. Cutting fluid can play the role of washing, cooling, lubrication and rust prevention, reducing tool wear. However, some additives in cutting fluid will make cobalt leaching in cemented carbide and tungsten carbide oxidation dissolution and then leaching, destroy the structure of the tool material, accelerate the tool wear. The wear mechanism of triethanolamine solution, sodium carbonate solution, borax solution, benzotriethanolamine solution, oleate triethanolamine solution and oleate triethanolamine, benzotriazolazole and borax solution on cobalt and tungsten carbide in cemented carbidecutting tools was studied by immersion test and energy spectrum analysis. The results showed that borax solution, benzotriazole solution, oleate triethanolamine solution and oleate triethanolamine, benzotriazole and borax composite solution could inhibit the leaching of cobalt and tungsten carbide. At 150degrees , the cemented carbide soaked in borax solution showed no cobalt leaching, and the tungsten leaching rate was 2.88%. The mechanism of borax is as follows: the polarization reaction between the cemented carbide and the system formed by the borax solution slows down the corrosion rate of the cutting tool and inhibits the leaching of cobalt and tungsten from the cemented carbide cutting tool. At room temperature and 150degrees , benzotriazole solution has no leaching effect on cobalt in cemented carbides.

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The strength of cemented carbide is one of the key indexes of product toughness and impact resistance. In the field of metal cutting, such as discontinuous cutting and non-uniform cutting (including black leather cutting), tool fracture or breakage is the most important failure mode, so it puts forward very high requirements for the strength of cemented carbide matrix.

In the modern cutting, the introduction of tungsten carbide coatings technology makes the tool high temperature resistance, wear resistance, corrosion resistance and other properties have been greatly improved, to meet the requirements of high-speed processing. However, because the impact resistance of coated tools in high-speed machining is not ideal, most of the rough machining field with bad working conditions in China is still using non-coated tools with very low cutting efficiency. Through analysis and research thinks, coating process of cemented carbide substrate for a long time at 500 degreesto 1100 degrees, to be able to produce adverse effect to the strength of the matrix, the impact resistance performance of coated tools.

Test plan and test results

The test selects 6 kinds of k-series coated cemented carbide matrix brands, matrix WC particle size are 0.4 m, 0.6 m, 0.8 m, 1.5 m, 3.0 m and 4.0 m, the main component is WC+Co, containing trace additives. Select the same batch of raw materials for each brand, and press 30 strength test strips of 5.25mm 6.5mm 20mm respectively, and then sintering them together in the same furnace and vessel at one time. 10 grinding samples were taken for strength testing, and 10 unground blank samples were taken for CVD coating and 10 samples for PVD coating. The strength of cemented carbide matrix was tested by grinding the coated strip and testing the strength of cemented carbide matrix.

The change of strength of substrate with different particle size before and aftertungsten carbidecoatings. Except for the accidental factors such as abrasive sample and human operation in the test, it can be seen from figure 1 that the change trend of strength is obvious. The strength after sintering of the same matrix brand is >PVD coating, >CVD coating.

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1.Has high toughnessDuring the extrusion process, the mold must withstand complicated loads such as excessive pressing force, bending stress and impact. Therefore, the selected materials should have high toughness after heat treatment. Therefore, the mold material should have Good hardenability, so as to ensure the mold can be hardened and evenly organized. Large blocks of carbides and severe defects such as severe deflection, fiber orientation and non-metallic inclusions can reduce the toughness of the mold or cause stress concentration during load, causing early damage to the mold.

2.Good wear resistanceThe mold should have high wear resistance to ensure a normal service life and produce a large number of qualified extrusion parts.In general, the hardness and wear resistance of steel are proportional to certain conditions, so it is required that the mold material not only has sufficient hardenability, but also has high hardenability. However, in addition to the hardness, the wear resistance of the steel is determined by the thickness, composition, excess and tempering precipitation of the tungsten carbide die phase after heat treatment, size, type, dispersion and red hardness. For example, high-speed steel and low-alloy tool steel, although they have the same hardness value after heat treatment, the wear resistance of the former is much higher in actual use, while the hard alloy containing 80% or more of WC has higher wear resistance than steel. Ten times, so in the large-scale extrusion production, in order to obtain the long service life of the mold, high-speed steel and hard alloy with high cost and complicated process are still used as the mold material.

3.Adequate thermal stabilityWhen continuous production, the temperature rise of the tungsten carbide diesometimes reaches or exceeds 200 degrees. This is the mold material with tempering temperature of 160-180 degrees, which will reduce the strength and hardness. Therefore, the mold material with higher temperature rise should be used. Good resistance to tempering.

4.Good processabilityThe cold extrusion die has a long manufacturing cycle, complicated process and high precision. Generally, it must be forged, cut, heat treated, ground or otherwise finished. Therefore, only materials with relatively good processability can meet the needs of production.

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Ultrasonic machining diamond die has long been used in domestic applications, but in the tungsten carbide wire drawing dies processing is currently a small number of, especially the larger aperture wire-drawing die is so. Ultrasonic grinding is a frequency of about 20,000 cycles per second from electrical energy into mechanical energy (20,000 times/second for longitudinal movement); Fast moving processing equipment. In the processing of diamond mold, its copy needle and the link of the spokes are now used in domestic complex softbank welding device, otherwise the processing efficiency will be greatly reduced. Due to the processing speed, if the cemented carbide drawing die processing, according to the requirements of process strictly every processing a wire-drawing die need to replace a needle, the atmosphere day frequently change requires a lot of needle, the needle and complex welding must be conducted, it is seriously hampering the this technology in the application of cemented carbide drawing to touch. In addition, because the processing speed is fast, difficult to master, it is not easy to achieve linear processing, energy and the need for a high degree of concentration and many other factors, therefore, in the promotion and use is also limited.

Wire is machined by passing through small holes in a drawing die to reach a specified diameter. The process is called drawing. Although the principle of wire drawing is very simple, it is rather complicated from the mechanical point of view. Although many theories and speculations have been published to explain the mechanical principles involved in wire drawing, many aspects remain unexplained. Drawing dies are probably the simplest type of tool used in industry to deform metals. The most basic form of a drawing die is a metal block with a tapered hole. People have used this structure of the wire drawing die for more than 500 years, tungsten carbide wire drawing die is still based on the above basic form, but in some aspects made improvements. In 1923,Karl Schroter discovered that a mixture of tungsten carbide powder and drilling, iron or nickel (10% by weight) metals could be pressed and sintered to produce a material with low porosity, high hardness and high strength. He produced die cores that could be used to draw tungsten wires and successfully promoted them to the electric lamp industry. Soon this new material is widely used in the nonferrous metal wire industry. In the mid-1930s, the cemented carbide mould was also widely used in the us steel wire manufacturing industry. Modern cemented carbides are similar to the materials schroter produced in those days.

Thetungsten carbide drawing dieis one of the important tools to produce metal wire, and its quality will directly affect the output and quality of metal wire. There are many factors that affect the service life of the wire drawing die, such as the quality of the material of the wire drawing die itself, the geometry of the wire drawing die, the surface reduction rate of the metal wire, the lubrication effect of the lubricant, the quality of the wire drawing die and the cooling mode of the wire drawing die in the process of use. Due to the wide use of high-speed wire drawing machine, the research on the design of high-speed wire drawing die for high-speed wire drawing machine and extending the service life of the die has been carried out at home and abroad, such as the improvement of the die core material and the research on the pass theory and so on. High-speed wire drawing, because of the speed increase, can bring a series of problems, such as fever, wire drawing die wear such as intensifying make life of drawing die is reduced, the following will only from wire drawing die wire drawing die of calculating and analyzing the power and force of geometric parameters and the relationship between the wear and tear, determine the optimal geometric parameters of drawing die and to reduce wear and prolong the service life of drawing die.

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The tungsten carbide drawing die is one of the important tools to produce metal wire, and its quality will directly affect the output and quality of metal wire. There are many factors that affect the service life of the wire drawing die, such as the quality of the material of the wire drawing die itself, the geometry of the wire drawing die, the surface reduction rate of the metal wire, the lubrication effect of the lubricant, the quality of the wire drawing die and the cooling mode of the wire drawing die in the process of use. Due to the wide use of high-speed wire drawing machine, the research on the design of high-speed wire drawing die for high-speed wire drawing machine and extending the service life of the die has been carried out at home and abroad, such as the improvement of the die core material and the research on the pass theory and so on. High-speed wire drawing, because of the speed increase, can bring a series of problems, such as fever, wire drawing die wear such as intensifying make life of drawing die is reduced, the following will only from wire drawing die wire drawing die of calculating and analyzing the power and force of geometric parameters and the relationship between the wear and tear, determine the optimal geometric parameters of drawing die and to reduce wear and prolong the service life of drawing die.

Wire is machined by passing through small holes in a carbide drawing dieto reach a specified diameter. The process is called drawing. Although the principle of wire drawing is very simple, it is rather complicated from the mechanical point of view. Although many theories and speculations have been published to explain the mechanical principles involved in wire drawing, many aspects remain unexplained. Drawing dies are probably the simplest type of tool used in industry to deform metals. The most basic form of a drawing die is a metal block with a tapered hole. People have used this structure of the wire drawing die for more than 500 years, hard alloy wire drawing die is still based on the above basic form, but in some aspects made improvements. In 1923,Karl Schroter discovered that a mixture of tungsten carbide powder and drilling, iron or nickel (10% by weight) metals could be pressed and sintered to produce a material with low porosity, high hardness and high strength. He produced die cores that could be used to draw tungsten wires and successfully promoted them to the electric lamp industry. Soon this new material is widely used in the nonferrous metal wire industry. In the mid-1930s, the cemented carbide mould was also widely used in the us steel wire manufacturing industry. Modern cemented carbides are similar to the materials schroter produced in those days.

Posted by: hannahgwendolyn at 09:46 AM | No Comments | Add Comment
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Wire is machined by passing through small holes intungsten carbide wire drawing diesto reach a specified diameter. The process is called drawing. Although the principle of wire drawing is very simple, it is rather complicated from the mechanical point of view. Although many theories and speculations have been published to explain the mechanical principles involved in wire drawing, many aspects remain unexplained. Drawing dies are probably the simplest type of tool used in industry to deform metals. The most basic form of a drawing die is a metal block with a tapered hole. People have used this structure of the wire drawing die for more than 500 years, hard alloy wire drawing die is still based on the above basic form, but in some aspects made improvements. In 1923,Karl Schroter discovered that a mixture of tungsten carbide powder and drilling, iron or nickel (10% by weight) metals could be pressed and sintered to produce a material with low porosity, high hardness and high strength. He produced die cores that could be used to draw tungsten wires and successfully promoted them to the electric lamp industry. Soon this new material is widely used in the nonferrous metal wire industry. In the mid-1930s, the cemented carbide mould was also widely used in the us steel wire manufacturing industry. Modern cemented carbides are similar to the materials schroter produced in those days.

Production of steel wire and tungsten carbide wire drawing dies using a large number of die hole diameter and advised 3, 10 mm hard alloy drawing die. Die hole grinding BBB 0 0.5~1 mm. The grinding of each part of the hole with the working belt takes the most time. For example, by dk5 mm heavy grinding to 5.5 mm, rough grinding to dozens of minutes, fine grinding at least 3, 5 minutes. Generally, the grinding cone is first mechanically rough ground with boron carbide grinding paste and taper point steel needle, and then fine ground by hand with diamond powder grinding paste and steel or wood grinding needle. The institute of superhard materials, part of the Soviet academy of sciences, worked with a number of factories to develop a new method of electrolytic cathode grinding. Grinding is divided into two steps: first, in the sub-micro cutting conditions, electrolytic method of high efficiency rough grinding; Then mechanical fine grinding (polishing), so that the surface roughness Ra up to 0.08 micron. The same needle (cathode) is used for both steps. During rough grinding, the die hole of the drawing die is concentric with the grinding needle (cathode). Fine grinding, grinding needle up and down and around at the same time. The spindle head frame of the mould grinding machine can ensure that the polycrystal on the grinding needle is always in close contact with the grinding hole surface. The needle (cathode) is a tapered steel needle with a ring of cylindrical polycrystals embedded in the needle. 2-0.3 mm. Polycrystals are made from scrap diamond molds and polished with diamonds.

Due to the wide use of high-speed wire drawing machine, the research on the design of high-speed wire drawing die for high-speed wire drawing machine and extending the service life of the die has been carried out at home and abroad, such as the improvement of the die core material and the research on the pass theory and so on.

Related link:

http://www.wococarbide.com/Library/libraryinfo/id/1397

Posted by: hannahgwendolyn at 09:38 AM | No Comments | Add Comment
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Spraying should be as far as possible on the surface of the coated workpiece polished smooth, smooth, the surface without oxide and micro-pores, if conditions can also be pre-baked, but also effectively reduce the formation of particles.

For the technical personnel ofthermal powder spraying, all understand that if the coating film is too thin, in addition to the appearance of particles, will also produce flow adjustment, orange peel serious, and light color varieties of poor hiding power, at the same time coating film acid, alkali, salt, water resistance and other poor performance. Appropriate increase in coating thickness, can effectively reduce the formation of particles, coating film should not be too thick, generally too thick will affect the size of the coated workpiece, in impact resistance, flexibility, adhesion and other properties decline, general coating thickness control in 40~120um is normal. We can control the film thickness by the following ways: a. the number and arrangement of spray guns in the powder chamber; B. Powder output and air pressure of the spray gun (powder output, atomization and fluidization parameters); C. The running speed of the transmission chain, that is, the chain speed; D. Suspension and arrangement of coated workpieces.

For most enterprises, the recycled powder is generally treated as follows

1. In the automatic powder coating system recovered by the conveyor belt, the escaped powder is automatically recovered and sifted, and then mixed with the new powder coating to continue to be supplied to the powder spraying gun. The quality of such recovered powder is relatively stable and it is not easy to produce particles;

2. In the two-pole recovery system of cyclone separator and bag filter, the powder recovered in the first stage of cyclone separator has little influence on coating and is not easy to produce particles when it is sifted by vibrating screen and circulated with the powder supply system;

3. for the manual spraying coating system to recover the powder, because the dust and impurities in the environment is easy to bring into the recovery of powder, recovery must go through more than 120 mesh vibration screen. For the recycling and reuse of powder, the powder adsorbed on the profile surface only accounts for about 1/3 of the powder output of all the spray guns. There are many powders scattered after thermal powder spraying. The recycled powder must be mixed with the newly added powder in an appropriate proportion to achieve good results.

Related link:

http://www.wococarbide.com/Transaction/en_article_info/id/643.html

Posted by: hannahgwendolyn at 09:47 AM | No Comments | Add Comment
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