The thickness of coating is one of the important marks to measure the quality of coating. The thickness of the coating affects the reliability and use value of the product to a great extent. Through the detection of coating thickness, in addition to evaluating whether the workpiece with tolerance index or repair size requirements is reasonable, it can also directly or indirectly evaluate the corrosion resistance, wear resistance, porosity and other properties of thermal spraying coating. Therefore, it is widely used in coating quality inspection and process research.

The inspection of coating thickness is generally divided into two types: average thickness and local thickness. Because the local thickness can reflect the quality of the product better than the average thickness in practical application, in most cases, the local thickness or the local average thickness of the coating is measured. During thickness measurement, at least three thicknesses shall be measured at representative or specified positions, and the average value shall be calculated as the result of thickness measurement.

There are two kinds of testing methods for coating thickness: destructive testing and nondestructive testing. Destructive testing methods include: drop method, liquid flow method, chemical dissolution method, coulometric method, metallographic microscope method, profile method and interference microscope method. Nondestructive testing methods include magnetic method, eddy current method, X-ray fluorescence thickness measurement method, ray back scattering method, light cutting microscope method and energy spectrum method.

Here are several common methods for measuring the thickness of thermal spraying coating

Metallographic microscopy is one of the physical methods to measure the coating thickness. The normal metallographic method is used to make the section sample of the coating to be tested, and then the magnified image of the vertical section of the coating to be tested is observed on the metallographic microscope with a micrometer eyepiece, so as to directly measure the local thickness of the coating. This method has the advantages of high measurement accuracy, sufficient basis, intuitive judgment and so on, because it directly measures the section thickness of the coating under a certain magnification. However, the operation of this method is relatively complex when the sample is made, and it is generally used for strict thickness control, or other thickness measurement methods to verify and arbitrate the test pieces with disputed results or for laboratory measurement.

Metallographic thickness measurement is a method to observe and measure the thickness of the longitudinal section of the coating by using a special metallographic microscope with a certain magnification and a micro eyepiece. In order to make the cross section of the coating meet the requirements of metallographic microscope, the coating to be tested shall be cut, edge protected, inlaid, polished and chemically etched before thickness measurement, and then the coating to be tested shall be made into the qualified sample.

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An improved wax-based multi-component binder and a new debinding method termed high-pressure condensed solvent extraction were developed for powder injection molding of tungsten cemented carbide. The results indicate that a critical powder loading of 65% (volume fraction) and an ideal rheological properties were obtained by the feedstock based on the binder. High debinding rate and specimens with high strength were obtained by the debinding method. Moreover, by making high temperature holding time adjustable, it makes the subsequent thermal degradation process more flexible to debinding atmosphere and carbon content of the as debinded specimens controllable. The transverse rupture strength, hardness and density of the as-sintered specimens made by an optimized PIM process are 2.48GPa, HRA90 and 14.72g/cm3, respectively. Good shape retention and about 0.02% dimension deviation were achieved.

The invention relates to a binder for injection molding of titanium alloy powder and a method for injection molding of titanium alloy parts, belonging to the technical field of titanium alloy parts processing. The binder is composed of polypropylene, low density polyethylene, paraffin, stearic acid and naphthalene.

The method is as follows: the spherical powder of titanium alloy is put into the mixer for heat preservation and preheating, polypropylene and low density polyethylene are put in; The temperature was lowered to 50 degrees for heat preservation, component B was added, the rotating speed was adjusted for mixing, and the temperature was lowered to toothpaste shape for extrusion granulation. Then, injection molding, degreasing, vacuum sintering and furnace cooling were carried out successively to obtain titanium alloy parts. The advantages of the invention is: the existing basic load between 55% ~ 65%, the invention adopts a load of 68%, reduce the proportion of the binder, can say, in the process of feeding with high loading capacity also can guarantee the mixture has good rheological properties, filling, easy to get green for mold shape, and no defects.

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The effects of a new type of grain growth inhibitor on vacuum sintering behavior of nanograined WC-10Co powders produced by mechanical alloying as well as its affecting mechanism were investigated. The results show that the new grain growth inhibitor can promote sintering densification process. Adding the new inhibitor to traditional transitional group element carbides, composite inhibitors become much more effective, obviously induce oriented WC grain growth and evidently encumber plate-like WC grain formation during sintering. For WC-10Co0.8VC/Cr3C2powders with 0.1% of the new additive, the density of 14.48 g/cm3can be achieved after sintering at 1 375degrees for 30 min, corresponding to the grain size of 160 nm and the micro-hardness of 2.150 GPa.

Cemented carbideis a kind of hard and brittle composite material which is different from soft metal material and hard and brittle ceramic material. Due to the different content of soft metal phase and hard phase in the material, the microstructure of the material is different, resulting in the different grinding performance of the hard alloy. The excellent physical and mechanical properties of cemented carbide contribute to the application of this kind of material in engineering, but the high hardness and high wear resistance also make it very difficult to grind it. The purpose of this project is to apply the high speed grinding technology to the processing of hard alloy, deeply study the grinding mechanism of hard alloy and the grinding mechanism of high speed grinding, and provide an effective scheme, experimental basis and theoretical basis for the solution of this difficult problem.

VC and Cr3C2 with different content of grain growth inhibitors were added to the ultrafine WC Co composite powder. The phase composition of the powder and cemented carbidewas analyzed by X-ray diffractometer. The morphology of cemented carbide was observed by SEM and TEM, and the effect of different content of grain growth inhibitors on the microstructure and mechanical properties of cemented carbide was studied. The results show that with the increase of the inhibitor of grain growth, the abnormal grain growth disappears and the grains are fine and uniform; meanwhile, it is found that the increase of VC in WC Co composite powder can rapidly improve the hardness of cemented carbide, while the appropriate amount of Cr3C2 can effectively improve the transverse fracture strength of cemented carbide.

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Most hulls of the ships are protected with paintings, sacrificial anode, and impressed current cathodic protection methods against corrosion problems. However, these conventional methods are not very effective because the rudder of ships stern are exposed to very severe corrosive environment such as tides, speeds of ships, cavitations and erosion corrosion. The environmental factors such as cavitation and corrosion will cause damage for materials with the shock wave by the creation and destruction of bubble. To solve these problems, the cavitation and electrochemical experiments are executed for thermal spray coating with Al−Zn alloy wire material. Thereafter, and sealed specimens with F−Si sealer on Al−Zn alloy coated specimen are executed to improve electrochemical and anti-cavitation characteristics in sea water. The application of fluorine silicon sealing after spray coating of 15%Al−85%Zn seems to be appropriate not only in static environment but also in dynamic environment.

Thermal spray coatingpresents a sacrificial-anode cathodic protection method since differences between the potentials of materials are employed. If a base metal is exposed to seawater, due to defect in the thermal spray coating, the metal is protected by the sacrificial anodic characteristics of the coating layer because micro-cells formed by the base metal and the thermal spray coating act as cathodes and anodes, respectively. The coating thickness has little effect on the surface morphology of the coating. However, the electrochemical properties with the increasing of coaBased on the excellent properties of nano coating, the preparation process of nano YSZ thermal spraying powder was studied. After spray drying, the fluidity, bulk density and microstructure of the aggregates were measured and analyzed by Holzer leak method and electron scanning microscope respectively. It is found that the higher the solid content, the better the fluidity and bulk density of the powder, but the higher the solid content will affect the granulation effect; in the case of a certain solid content, the better the fluidity of the agglomerated powder is after the slurry with moderate binder content is granulating. In order to obtain better agglomerate powder, the reasonable follow-up treatment method is plasma densification under the condition of 300A current and 40V voltage.ting thickness present good results.

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The new technology of ion source enhanced multi arc ion plating was used to prepare the gradient coating of alcrtisin with different gradient structure of Si layer on the surface of cemented carbide tools. The microstructure, residual stress, bonding strength, friction and wear of the coating, as well as the properties of milling and drilling gray cast iron were studied in detail. The results show that the alcrtisin coating with different Si layer gradient structure is mainly composed of (al, Cr) n, (al, Ti) n phase and amorphous Si3N4 phase. Among them, the G3 (gradient 3) coating with the most gentle gradient change of Si layer has higher bonding strength, lower residual compressive stress, friction coefficient and wear rate. Milling and drilling experiments show that the main wear mechanisms of coated tools are abrasive wear and adhesive wear. G3 coating reduces abrasive wear and has the highest milling and drilling life, which is mainly due to its gradient design with Si layer, appropriate compressive stress (- 3.8 GPA) and good film-based bonding strength. The results show that the cutting performance of the coated tool can be significantly improved by gradient design of Si layer.

In order to explore the wear law, cutting force and surface roughness of GH4169 processed by cemented carbide tools with different cutting distances, cutting tests were carried out on GH4169 materials. The evolution of carbide tool wear and its effect on cutting force and surface roughness are analyzed. The results show that with the increase of cutting distance, the wear area of the front cutter surface gradually expands, the wear forms of the front cutter surface are coating off, groove wear and adhesion wear, while the wear forms of the back cutter surface are coating off and micro-chip edge. The main reason for the wear of the front tool surface is that there are many hard particles and their strong viscosity in the superalloy materials. The overall variation trend of Fx, Fy and Fz is that the surface roughness first increases and then decreases with the increase of cutting distance, and the surface roughness of the specimen first decreases and then increases with the increase of cutting distance. When the cutting distance is 75m, the surface roughness is the smallest.

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Hard surface technology is of great significance to promote sustainable economic development and build an economical society. Forming hard wear layer on metal/alloy surface with hard surface technology can significantly improve workpiece life and save resources. Due to its high hardness, high abrasion resistance and corrosion resistance, tungsten carbide casting is one of the most widely used hard surface materials. The surface morphology, microstructure and particle size of cast tungsten carbide have a decisive effect on its application. The spheroidal _ fast cooling treatment of traditional cast tungsten carbide powder can significantly improve the toughness of hard surface materials containing cast tungsten carbide, and achieve the best combination of high abrasion resistance and high toughness of hard surface materials. At present, the most representative company in the world that can prepare spherical casting tungsten carbide powder on a large scale is Tekna company of Canada. The company USES high temperature plasma technology to prepare spherical casting tungsten carbide powder. Because of the large flow of Ar gas as plasma carrier and protective atmosphere, the production cost is relatively high. The preparation of spherical casting tungsten carbide powder has been reported at home and abroad. The preparation methods of spherical casting tungsten carbide powder are mainly divided into three categories, namely, plasma high-temperature technology represented by Tekna company. Liquid direct atomization forming technology (CN1486806), represented by hunan dinglixin material engineering center co., LTD and zigong cemented carbide co., LTD. CN1488463, atomization forming method for producing ball casting tungsten carbide powder, 2004.04.14); High temperature arc melting centrifugal fast cooling technology represented by zhuzhou huayang technology co., LTD and Woka Schweisstechnik GmbH (CN2714579, a spherical amorphous material preparation equipment, 2005.08.03; American patent 5089182, Process of manufacturing cast tungsten carbide spheres, 1992.02. 1 The preparation method of spherical casting tungsten carbide has some problems, such as large gas consumption, poor stability of spherical degree control due to strong impact of airflow in the pellet forming process. In addition, the above technologies also have problems such as wide particle size distribution of spheroidized powder, relatively poor controllability of particle size distribution, poor stability of preparation process, low production capacity and high maintenance cost of equipment.

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Coarse and uniform tungsten carbide powder has always been an urgent need for coarse crystal cemented carbide fabricators. This paper, through the study of tungsten powder classification and recarbonization process, effectively solves the phenomenon of coarse and fine powder clamping and produces coarse crystal tungsten carbide powder.

The properties of tungsten carbide and alloy made from graded and ungraded powders eliminate the defects in the microstructure of tungsten powder, but the high reduction temperature makes the tungsten powder aggregate and the size distribution of tungsten powder become wider. However, from the perspective of particle size distribution, the degree distribution becomes wider, especially the bimodal or multi-peak caused by this, and the particle size distribution of tungsten carbide powder produced by ungraded original tungsten powder is contrary to its properties. At the same time, low hydrogen will appear the material reduction not permeable wider) the proportion of fine particles and ultra-coarse particles is significantly than the grading after the thorough, refining and other phenomena. The existence of these defects will be in the subsequent process, the particle aggregation is also more serious, many particles shape irregular. To negative effects.

Carbide sintering process microtek structure formation and the production rate depends largely on the quality of the original tungsten powder directly determines the quality of the WC and alloy properties, the structure of the mixture of tungsten carbide powder particles energy state, making coarse grain tungsten powder grading can effectively change the performance of the powder, coarse clip to solve powder alloy need tungsten carbide powder with high internal energy (lattice distortion) and surface problem, reduce the minimum size and maximum diameter and average particle size difference degree, can, not powder grading structure is more complex, both the bulky crystal produced more crude and more uniform tungsten carbide powder; Due to the characteristic of tungsten, there are also aggregates. During the carbonization of coarse tungsten powder, it generally goes through the transition process from three phases to unbreakable, moderately broken before classification, and the agglomeration of two phases in the powder to single phase. The carbonization rate mainly depends on the separation of particles, which can effectively separate the powder and improve the evenness. The grading must be the rate at which the polycrystalline tungsten carbide shell layer pushes inward. Due to the strict and fine regulation of the system operation parameters of tungsten powder particles, according to the original size of the original powder, carbonization process needs to be in a certain high temperature and time characteristics, need to find the best operation process. It can be done completely. Fine particles are more likely to be completely carbonized in a short time. Tungsten carbide particles with polycrystalline shells are fused by "grain boundary moving to the position specified in the references for more stable energy".

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Cemented carbide cutter has a series of excellent properties, such as high hardness, wear resistance, good strength and toughness, heat resistance, corrosion resistance, etc., especially its high hardness and wear resistance, which are basically unchanged even at 500 degrees, and still have high hardness at 1000 degrees. Hard alloy is widely used as cutting tool materials, such as turning tools, milling cutters, planers, drills, boring cutters, etc. it is used to cut cast iron, non-ferrous metals, plastics, chemical fiber, graphite, glass, stone and ordinary steel, as well as heat-resistant steel, stainless steel, high manganese steel, tool steel and other difficult to process materials.

Some of the factors that affect the characteristics and application of cemented carbide tools include:

(1) challenging workpiece materials. Including alternative metal materials and hard to process alloy materials. Some of these materials are less than a quarter as workable as steel, and some can cost hundreds of dollars per pound.

(2) increasingly complex workpiece geometry. For example, thin-walled workpieces and aviation parts with complex shapes.

(3) large size workpiece. In particular, the demand for turbines and various heavy machinery parts is increasing. The high cost of each piece of these workpieces puts forward high requirements for the machining of tungstencarbidecuttingtools.

(4) increasingly special quality and performance requirements. For example, the requirements for the surface fatigue strength of the machined parts.

Analysis of the factors that determine the quality of cemented carbide tools

Hardness and toughness: carbide tools have unique advantages in both hardness and toughness. Tungsten carbide (WC) has high hardness (more than corundum or alumina), and its hardness seldom decreases when the working temperature increases. However, it lacks enough toughness, which is essential for cutting tool performance. In order to make use of the high hardness of WC and improve its toughness, people use metal bond to combine WC together, so that this material not only has the hardness far higher than that of high-speed steel, but also can bear the cutting force in most cutting processes. In addition, it can withstand the cutting high temperature produced by high-speed machining.

Therefore, the adaptability of cemented carbide tool performance to specific machining depends largely on the initial milling process.

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Distilled water and sodium carbonate solution were used to soak WC powder and cemented carbide blade, and the influencing factors and mechanism of WC leaching in cemented carbide were studied with the help of scanning electron microscope, X-ray energy spectrometer and other equipment. The results show that water and sodium carbonate can lead to WC leaching in cemented carbide, and the influence of sodium carbonate is very obvious at higher solution temperature. The existence of H+, OH- and HCO3- plasma in the cutting fluid is the root cause of WC leaching.

However, it has been reported in foreign literatures that amino additives can leach cobalt from cemented carbide tools, so they should not be used in grinding cemented carbide tools. As the binder of cemented carbide, the leaching of cobalt will greatly reduce the mechanical impact and service life of cemented carbide tools. At the same time, if the content of cobalt in the waste cutting liquid is too high, it is easy to pollute the environment and cause harm to the health of the operator. Triethanolamine oleic acid is the product of reaction between oleic acid and triethanolamine under certain conditions. Triethanolamine oleic acid was synthesized from ricinoleic acid and triethanolamine. The lubricant is used to soak the cemented carbide blade, and the grinding wheel is used to conduct wet grinding test on the cemented carbide blade with lubricant.

The main metal components on the blade surface were analyzed by KYKY2880 SEM. According to the test results, a method was proposed to add triethanolamine oleate and borax in the cutting fluid to inhibit cobalt leaching from carbide tools.

Test conditions and methods

(1) triethanolamine oleic acid and triethanolamine were prepared by reacting at a molar ratio of 1.5:1 at a temperature of 80-100 ° c for 5-6 hours to synthesize triethanolamine oleate. The concentration is 0. 6% lubricant. The compound solution was prepared with triethanolamine oleate and borax (0.6% triethanolamine oleate and 0.3% borax mass).

(2) grinding test

The wet grinding test of YG8 cemented carbide specimen was carried out on CA6140 lathe with diamond grinding wheel (particle size 80#, grinding wheel diameter 200mm). Install the grinding wheel on the self-made mandrel, one end of the mandrel is mounted on the three-jaw chuck, the other end is supported by the center, and the mandrel is driven by the spindle of the machine tool to rotate (rotation speed: 1120r/min). The carbide specimen is fixed on the tool rest and fed manually. Grinding time is 10 minutes

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At present, almost all the famous cemented carbide cutting tools and knife auxiliary tools companies and their products have entered China. Many companies have also invested in factories in China to provide carbide cutting tools and technical support services to domestic automobile manufacturers. Domestic cemented carbide tool manufacturing enterprises are also trying to improve the design, manufacturing, grinding and coating of cemented carbide tool technology level, in order to adapt to the domestic automobile manufacturing industry using a large number of CNC processing equipment, constantly to high-speed, high-precision processing development requirements. All these provide good external conditions for the automobile manufacturing industry to further improve the application and management level of cemented carbide cutting tools.

Whether it is the centralized and unified management of cemented carbide tools carried out by automobile manufacturing enterprises themselves, or the management of cemented carbide tools outsourced, or the management ofcarbide cutting toolscombined with the two, they will make full use of social resources. This is the inevitable result of economic globalization and industrial informationization, as well as the inevitable trend of development of cemented carbide tool management.

Automobile manufacturing enterprises with the carbide cutting tools manufacturing and service enterprises to establish long-term cooperative partnership, established in computer and information technology on the basis of cemented carbide tool information database management software and carbide cutting tools production and demand will further develop communication, between customers and suppliers, problems and solutions.

With the establishment of some professional cemented carbide tool research and development, cemented carbide tool manufacturing, cemented carbide tool grinding and cemented carbide tool coating companies and their extensive service outlets in China, the management of cemented carbide tool in the automobile manufacturing industry will get more powerful support. Other auxiliary tools such as various new tool handle systems, carbide tool adjustment, testing equipment, carbide tool dynamic balance system and their suppliers will also be developed in China along with the rapid development of automobile manufacturing industry and the demand of carbide tool management, and provide effective services and support to automobile manufacturing industry.

The materials used for making carbide cutting tools must have high hardness and wear resistance at high temperature, necessary bending strength, impact toughness and chemical inertness, good technicality (cutting, forging and heat treatment, etc.), and not easy to deform.

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Electrostatic powder spraying is the use of high voltage electrostatic corona electric field principle. The metal guide ring on the head of the spray gun is connected with the high pressure negative electrode and is grounded to the positive electrode by the coated workpiece. A strong electrostatic field is formed between the spray gun and the workpiece. When shipping carrier (compressed air) to pass through the duct powder for powder coating from the unit to the spray gun guide ring, due to the guide ring connected to high voltage anode produce corona discharge, the surrounding to produce dense and make the powder with negative charge, charge in electrostatic force and compressed air under the joint action of the two force, powder spray gun from the mouth to fly to the workpiece, and adsorb evenly on the workpiece surface, and dissolved by heating the powder a flat to a uniform, continuous, smooth, glossy coating.

The first stage: under the action of electrostatic electric field force, the powder evenly adsorbs on the surface of the workpiece, forming a thin continuous covering layer. In this stage, the powder is basically adsorbed by the workpiece.

The second stage: powder under the action of static electric field, continue to fly to the workpiece surface, because of has been covered with powder and powder in the same electric charge and produce new repulsion, but static electric field strength is stronger than the repelling force, powder will continue to adsorption, thickening of coating will continue, but there are some powder adsorbed on the surface and not drop down.

The third stage: with the continuous increase of coating thickness, the repulsive force increases. When it reaches the same with the electrostatic field force, the powder will no longer be adsorbed. At this time, the coating thickness will no longer increase, and the ejected powder will not be adsorbed completely.

Of course, powder coating in the current process also has some shortcomings, such as powder xu material can not be as liquid coating can be quickly changed color; Uneven powder on the edges and corners of the powder coating; Powder coatings can not be as easily obtained as solvent based coatings. High curing temperature required for powder coating; When the dust concentration of powder coating construction site is too high, there may be danger of dust fire and explosion.

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The working principle of thermal spraying determines that the coating pores are inevitable. When the coating is used to prevent corrosion, the corrosive medium will reach the surface of the substrate through the pores, resulting in failure of protection. Therefore, sealing is an important way to improve the corrosion resistance of coating. In this paper, the methods of coating sealing hole are summarized, the prospect of coating sealing hole technology in the future is prospected, and a new coating sealing agent, glaze, is put forward.

At present, the commonly used methods to reduce the porosity of coating are thermal diffusion remelting, self-sealing coating, improvement and improvement of spraying process, hole sealing agent and so on.

Thermal diffusion remelting

Remelting is a process of reheating and melting the formed coating to make the coating more compact in order to eliminate the pores generated by spraying and improve the corrosion resistance and bonding strength of the coating. During remelting, the components in the coating that are easy to melt are melted, and the liquid phase is generated to help strengthen the diffusion process, permeate the components and slag formation of oxides, so that the coating has a certain shrinkage. The melting results make the bonding zone between the thermal spray coating and the substrate change from the original stacked layer-like structure to the dense and more uniform structure, and the pores decrease or even disappear. The heating methods of coating melting include gas combustion heating, atmosphere control furnace heating and high-frequency induction heating, etc. In recent years, we have developed laser, electron beam, plasma beam, solar energy and other heating methods.

The use of spray material itself to reduce porosity

Improve spraying method and process

When spraying, select appropriate spraying distance, main gas flow and powder feeder flow, gun speed, electrical power, powder particle size and other parameters to reduce the coating porosity and improve the bonding strength is very helpful.

Hole sealing agent for hole sealing treatment

Other ways to reduce porosity

Impregnation of low temperature solder for tungsten carbide coating improves strength and wear resistance. The process is carried out in vacuum at 1000 degrees or hydrogen at 800 degrees. At these temperatures the filler flows into the gap to fill the unmelted carbide and capillary action occurs rapidly, allowing for 12min. It has been confirmed that most lead, tin, silver and copper solders provide satisfactory results.

Mechanical treatment somethermal spray coatingscan be mechanically treated to close pores connected to the surface and improve smoothness. Shot hardening is used on some aeronautical parts. Active metal coatings can be improved by shot hardening and rolling to improve cavitation resistance.

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In the traditional cutting process, in order to improve the machining quality and extend the tool life, a large amount of cutting fluid is usually used. In the 21st century, people began to advocate "green manufacturing" dry cutting technology without cutting fluid is favored, especially the development of tool coating technology makes the application of dry cutting is expanding. But practice has proved that in the difficult processing materials (such as heat resistant steel, stainless steel titanium alloy, etc.) and difficult processing processes (such as drilling, tapping, cutting groove, especially deep hole processing, etc.) in the cutting process, even if the use of coating tool for dry cutting still have some difficulties, therefore, it is necessary to develop a new cooling lubrication way. This topic about carbide cutting tools and small Quantity Lubrication (Minimum Quantity Lubrication, MQL) and air cooling cutting technology, combining of austenitic stainless steel cutting experiment research has important practical significance. The study on austenitic stainless steel ICr8Ni9Ti material, before using the blade and knife surface coated respectively after TiCN + Al_2O_3 and Al_2O_3 TiCN + + TiN coating cemented carbide blade, through the cutting experiment was carried out, analysis in dry cutting, different bearing fluid for MQL, low temperature cold wind, and the change rule of cutting force under the condition of low temperature MQL, on this basis, to choose the right condition, cooling and lubrication for tool wear test, emphatically analyzes the characteristics of tool wear and wear mechanism of chip morphology after test observation, analysis the mechanism of chip breaker.

Through the experiment of cutting austenitic stainless steel 1Cr18Ni9Ti by four kinds of coated carbide cutters, the influence of cutting parameters on cutting force was studied, and the cutting force of four kinds of cutters was compared and analyzed. The test results show that the back force is larger than the main cutting force when cutting with small feed and small back feed. With the increase of cutting speed, cutting force of YBC251 and GC2025 cutting tools decreases first and then increases. Compared with CVD coated carbide cutting tools, pvd-coated carbide cutting tools of the same type have significantly less cutting force than cvd-coated carbide cutting tools.

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Coating material aspect. Such as cast iron, cast aluminum pieces have sand holes, or hot rolled steel plate surface rough, have fine holes, etc., these conditions will make the coating prone to appear sand (particles) or volcanic pits. This is because when baking curing powder coating, powder coating melt flow makes the coated surfaces closed at ordinary times, as the coated temperature increases, the coated sand holes or pores of air pressure, melt flow flat coating to hog, if internal pressure is not broken drum coating to form sand (particles), when drum coating and coating cannot heal when formation volcanic crater.

The most fundamental measure to solve this problem is to ensure that there is no sand hole in cast iron and cast aluminum. The surface of hot milk steel plate is flat without oxide skin and pores. If the material selection can not be solved, from the aspect of coating process, will be preheated, the use of thermal spraying process can solve this problem; In addition, the process of spraying twice can also solve this problem, but these two methods are more troublesome, and also increase the cost of coating.

If it is difficult to solve from the powder spray coating factory, you can also ask the powder coating factory to cooperate to solve. When the material quality of the coating can not be solved, it is the most effective method to solve from the powder coating production formula.

From the point of view of the powder coating factory, you can add defoamer and other additives in the formula to reduce the surface tension of powder coating in the melt flow at ordinary times, so that the air is easy to escape from the coated material sand holes or pores, at the same time, the air gap (hole) after the escape from the air can quickly smooth without leaving traces. In some cases, it is also necessary to adjust the reactivity of the powder coating to slow down the curing rate of the powder coating, so that the pores after escaping from the air have enough time to fuse and level out, without leaving behind the coated sand (particles) or volcanic crater.

The surface treatment of the coating is not good, the phosphating residue and other impurities in the surface treatment liquid are still attached to the surface of the coating, and it is easy to produce particles or particles of the coating film during powder spraying. This problem can be solved as long as the residue in the phosphating solution is cleaned in time and the coating is cleaned in the washing process.

In electrostatic powder coating, the production environment around the powder spraying room is not clean, especially some dust and particles in the air are brought into the powder coating or powder spraying room, or because of electrostatic induction effect, charged impurities are adsorbed to be coated above, in powder coating melting flow usually, become the particles or particles in the coating film. This problem can be solved by separating the powder spraying room from the production workshop to prevent the dust and dirt from entering the powder spraying room, and at the same time, the air entering the powder spraying room can be seriously purified. If the friction charge electrostatic powder spray gun is used, the dust in the environment will not be electrostatic, in contrast, the coating is less likely to produce particles (particles) caused by dust and other impurities in the air.

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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.

Related link:

http://www.wococarbide.com/Transaction/en_article_info/id/851.html

Posted by: hannahgwendolyn at 09:54 AM | No Comments | Add Comment
Post contains 478 words, total size 4 kb.