Posted by: hannahgwendolyn at 09:48 AM | No Comments | Add Comment
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The selection of the design parameters of cemented carbide toolsdirectly affect the reliability of tool and work piece precision. Stress - strength interference (SSI) model, to establish the mathematical model, the dynamic reliability of cemented carbide cutting tool cutting tool in cutting process is given reliability. On the basis of this combined with sensitivity analysis method, carbide cutting tools of physical parameters and material parameters is deduced the formula of dynamic reliability sensitivity, and gives the dynamic reliability sensitivity of each parameter curves. The results show that as the machining time and with the increase of number of impact loading tool in the sensitivity of each parameter is also gradually increasing The sensitive parameters can be controlled by direct or indirect means to reduce the influence on the tool reliability, thereby improving the tool reliability and the precision of the processed parts.this method provides a theoretical reference for improving the reliability of the tool system and the whole machine tool.

With the rapid development and progress of metal cutting technology, and the improvement of the degree of automation, indexable cutting tools are more and more widely used. In the process of using cemented carbide tools, the blade is directly in contact with the processing workpiece parts, in the process of bearing a large external force, in order to meet the processing requirements, too much stress on the blade will produce damage, the damage of the blade will make the whole processing process to stop, thus affecting the processing efficiency. The maximum stress on the blade is mainly affected by the main deviation Angle, blade inclination Angle and other geometric angles, but the degree of influence of each factor on the blade is different. Therefore, it is necessary to determine the degree of influence of these factors and to control each factor reasonably. On the basis of summarizing the research status of reliability at home and abroad, this paper firstly establishes the three-dimensional model of indexable blade, analyzes the static characteristics of blade by using finite element method, and obtains the maximum static stress of blade. Secondly, in view of the shortcomings of previous numerical calculation methods for reliability, the neural network theory is introduced based on the reliable theory and the finite element method in blade mechanics solution, and the neural network technology is applied in the field of reliability sensitivity analysis and reliability robust design. The function of nonlinear mapping and approximation of arbitrary function of neural network are fully utilized.

With the development of high-speed and ultra-high-speed cutting, precision die and tool manufacturing, nano-machining and micro-machining, the requirement of cutting performance of cutting tools is increasing day by day. Compared with ordinary medium grain size and fine grain cemented carbides, ultra-fine wc-co class cemented carbides have higher hardness, abrasion resistance and transverse fracture strength.

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Posted by: hannahgwendolyn at 09:54 AM | No Comments | Add Comment
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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.

Posted by: hannahgwendolyn at 09:39 AM | No Comments | Add Comment
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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.

Posted by: hannahgwendolyn at 09:40 AM | No Comments | Add Comment
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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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Posted by: hannahgwendolyn at 09:20 AM | No Comments | Add Comment
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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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Posted by: hannahgwendolyn at 09:49 AM | No Comments | Add Comment
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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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Posted by: hannahgwendolyn at 09:52 AM | No Comments | Add Comment
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