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Tungsten Carbide Rods Performance Introduction
Tungsten Carbide Rods is an alloy material made of a refractory metal hard compound and a bonded metal through a powder metallurgy process. Carbide has a high hardness, wear resistance, strength and toughness is good, heat, corrosion and a series of excellent performance, especially its high hardness and wear resistance, even at 500 ℃ temperature is basically the same , At 1000 ℃ still have a high hardness.
Carbide is widely used as a tool material, such as turning tools, milling cutters, planers, drill bits, boring tools, etc., for cutting cast iron, nonferrous metals, plastics, chemical fiber, graphite, glass, stone and ordinary steel, can also be used to cut Heat-resistant steel, stainless steel, high manganese steel, tool steel and other difficult to process materials.
Tungsten Carbide Rods is tungsten steel round bar, also known as tungsten steel bar, simply is a tungsten steel rod or carbide rod. Carbide is made of powder metallurgy by the refractory metal compounds (hard phase) and bonding metal (bonding phase) composed of composite materials. Carbide is also known as tungsten steel, relatively speaking, is the difference between the local name.
Carbide (WC) is an inorganic compound containing the same amount of tungsten and carbon atoms. In its most basic form, it is a subtle gray powder, but it can be used in industrial machinery, tools, abrasive abrasives, and the formation of the use of the shape. Carbide carbon content is three times the steel, crystal structure than steel and titanium is also intensive. Its hardness is comparable with the diamond, can only be ground into a carbide, with cubic boron nitride abrasive grinding.
Tungsten Carbide Rods is a new technology and new material. Mainly used for metal cutting tool manufacturing, wood, plastic hardness and wear resistance of corrosion-resistant products manufacturing and other industries.
Tungsten Carbide Rods are characterized by stable mechanical properties, easy welding, high abrasion resistance and high impact resistance.
Tungsten Carbide Rods is mainly used for drill bits, end mills, reamers. It can also be used for cutting, stamping and measuring tools. It is used in paper making, packaging, printing, nonferrous metal processing industry. In addition, it is widely used in processing high-speed steel cutting tools, carbide cutter, carbide cutting tools, NAS cutting tools, aviation tools, carbide drill bits, milling cutter core drill, high speed steel, taperd cutter, metric Milling cutter, miniature end mill, hinge pilot, electronic tool, step drill, metal cutting saw, double guarantee diamond drill, gun pole, angle cutter, carbide cutting file, carbide cutting tools and so on. Use edits
Grade YG6, YG8, YG6X more wear than MK6, it can be used for hard wood, processing aluminum alloy profiles, brass rods and cast iron, YG10 grade wear resistance, percussion, for processing hard wood, soft Wood, ferrous and nonferrous metals.
One, two or three holes, 30 degree or 40 degrees spiral straight or twisted, or non-porous solid, they are used as manufacturing standards. Submicron grain grade YG10X end mills, drill bits, carbide rods are mainly used in non-ferrous metal precision cutting and submicron particle grade YG6X cutting and glass fiber reinforced plastic, titanium alloy, super hardened steel fine grain YG8X and so on.
Tungsten Carbide Rods can be used not only to cut and drill tools (eg microns, twiste exercises, exercise vertical mining tool indicators), but also as input pins, various roller wear parts and structural materials. In addition, it can be widely used in many fields, such as machinery, chemicals, petroleum, metallurgy, electronics and defense industry.
Tungsten Carbide Rods Performance Introduction Tungsten Carbide Rods is a carbide cutting tool that is suitable for different coarse grinding parameters, cutting materials and non-metallic materials. At the same time, carbide rods can also be used in traditional automatic, semi-automatic lathes and so on. The main process of milling → according to the requirements of the recipe → by wet grinding → mixing → crushing → drying → sieving → after adding molding agent → re-drying → after the preparation of the mixture → granulation → pressing → forming → low pressure Sintering → forming (rough) → cylindrical grinding mill (rough without this process) → detection size → packaging → storage.
Tungsten Carbide Rods Performance characteristics:
1, with high quality ultrafine tungsten carbide and imported cobalt powder as raw material.
2, the use of the world's advanced low-pressure sintering preparation technology for standardized production.
3, with high strength and high hardness.
4, with excellent red hardness, good wear resistance, high elastic modulus, high flexural strength, good chemical stability (acid, alkali, high temperature oxidation), good impact toughness, low expansion coefficient, thermal conductivity, Iron and its alloys are similar.
5, high-tech advanced equipment: Germany imported 10MPa low-pressure sintering furnace sintering.
6, the unique new technology: vacuum high temperature and high pressure sintering. Products in the final stage of the use of pressure sintering, greatly reducing the porosity, improve the density, greatly improve the mechanical properties of products.
7, the product features: material grades, can be used for different use needs; complete specifications, rough size precision (reduce processing capacity, improve production efficiency).
8, service and thoughtful response: the next single production fast, fast delivery on time (3 to 5 days)
High-end CNC machine tools through the "thirteen five" implementation plan
Recently, the "high-end CNC machine tools and basic manufacturing equipment," science and technology major projects (referred to as "CNC machine special") held in Beijing in 2017 the second expert advisory committee meeting to consider the special "three five" implementation plan (revised edition) and 2018 Guidance on annual project reporting. The meeting was chaired by the expert advisory committee Lu Yansun, expert advisory committee members, special promotion group and special office staff, the overall group of technical chief and some experts in the field attended the meeting.
The special group, the overall group, reported the special recent key work and the revision of the "13th Five-Year Plan" and the 2018 Guidelines. After full discussion, the Advisory Committee agreed to adopt the "13th Five-Year Plan" implementation plan (revised edition) and special 2018 guidance review.
Miao Wei has been in the high-end CNC machine tools and basic manufacturing equipment science and technology major projects to promote the application of the scene will be raised, high-end CNC machine tool is to achieve the cornerstone of industrial modernization, the development of high-end CNC machine tools, both industrial and information technology to deepen the supply side structural reform, To promote the construction of the power of the objective needs; is also the implementation of the integration of military and civilian development strategy to ensure the urgent requirements of national security.
Special implementation of more than eight years, the majority of machine tool enterprises, users and experts work together, tackling tough, made a number of gratifying results:
First, to enhance innovation, common technology research and innovation platform construction steadily. Heavy forging equipment, part of the machine host performance close to the international advanced level. Second, the whole industry chain layout, CNC system and other core components made a significant breakthrough. The gap between the function and the performance of the domestic CNC system has been greatly reduced. The key functional components such as ball screw, guide rail and power cutter are close to the international advanced level, such as precision and reliability. Third, adhere to the demand-oriented, key areas of equipment support capabilities continue to improve. Aerospace products in the field of typical products required for the key manufacturing equipment, "whether the problem" is gradually being resolved; automotive large parts automatic punching line global market share of more than 30%, the successful export of nine production lines.
Miao Wei stressed that we should earnestly study and understand the important instructions of General Secretary Xiu Pingping on the revitalization of the manufacturing industry, and comprehensively implement the strategic plan of the CPC Central Committee and State Council, firmly establish the new development concept, adhere to the supply side of the structural reform as the main line, Manufacturing 2025 ", focus on short board, improve the quality of development, promote the strategic transformation of manufacturing, accelerate the pace of building a strong country. Focus on doing four aspects of the work:
First, we should adhere to the innovation drive in a more prominent position, firmly grasp the high-end links in the industrial chain. Second, we must steadily carry out numerical control machine tool special demonstration demonstration application, promote the deep integration of military and civilian development. Third, we should give full play to the role of social intermediary organizations, bridges and ties. Fourth, we must scientific management, organization and implementation of special CNC machine tools.
This time, "high-end CNC machine tools and basic manufacturing equipment," a major scientific and technological projects through the "thirteen five" implementation plan (revised edition) and special 2018 guidelines review, made in China by the big change just around the corner.
Developing Trend and Application of Tungsten Carbide Woodworking Knives
Abstract：The characteristics, research and application status of the tungsten carbide material used for cutting wood are introduced, with the focus on the new research achievements and application field of coated tungsten carbide. Based on the cutting characteristics of wood and wood-based composites, the feasibility of its being applied in woodworking industry is discussed.
Key words：Tungsten Carbide Woodworking Knives；woodworking cutting tools；tungsten carbide；development
Cutting is one of the most basic, broadest and most important processes in the wood industry, directly affecting production efficiency, processing costs and energy consumption. With the progress of wood industry technology, all kinds of wood composite materials, plywood, wood, bamboo aggregates, especially melamine impregnated paper plywood, PVC plywood, Al2O3 reinforced plywood and other materials are increasingly used for furniture, Flooring, roof panels and engineering wood parts. These materials are difficult to cut, simple cutting processes, conventional tool construction and common tooling materials are difficult or impossible to achieve cutting. In addition, with the development of wood industry technology, wood-based panel production equipment, materials equipment, furniture manufacturing equipment, etc. are high degree of automation, full function, fast feed and high production efficiency. The progress of both technologies has contributed to the development of cutting tool materials and manufacturing technology.
Whether the tool can be properly cut, the quality of the cutting is good or bad, and the degree of durability is closely related to the material of the cutting part. Various physical phenomena in the cutting process, especially the wear of the tool and the nature of the tool material is extremely important. The machine's productivity is largely dependent on the cutting performance of its own material, subject to the machine's permission. The requirements for Woodworking Knives are at high speed and are subject to shock loads Conditions for a long time to maintain the sharp cutting tool cutting performance. To this end, Woodworking Knives must have the necessary hardness and wear resistance, sufficient strength and toughness, a certain process (such as welding, heat treatment, cutting and grinding, etc.)
1 Carbide Tool Material: Carbide is made of high hardness, refractory metal carbide (WC, TiC) with Co, Ni and other binder made of sintered powder metallurgy products. Its performance depends mainly on the type of metal carbide, performance, quantity, size and binder dosage. Carbide hardness of HRC74 ~ 81.5, its The hardness decreases as the binder content increases. Carbide high temperature carbide content of more than high-speed steel, so good thermoplastic, energy up to 800 ~ 1000 ℃ cutting temperature. 600 ℃ when the high temperature steel at room temperature hardness of more than 1000 ℃ when the temperature of carbon steel hardness. Wood, wood composite cutting tool mainly used to cobalt (Co) as a binder, tungsten carbide (WC) for the hard phase of the YG-type carbide.
Although the new variety of tool materials in recent years after another, but with the wood-based panel industry and the development of wood processing industry automation, cemented carbide this high wear resistance of the material has become the main woodworking tool materials, and in the future for a long time Will still occupy an important position in the wood cutting tool material. As the cemented carbide is brittle material, the bending strength is about 1/4 ~ 1/2 of ordinary high speed steel, the impact toughness is about 1/30 ~ 1/4 of ordinary high speed steel, the blade can not be grinding like high speed steel So sharp, so the need to research and develop new materials for the preparation of technology, to further improve and mention Cutting performance of high carbide cutting tool.
2 Carbide tool materials research and application status: As the carbide tool material wear resistance and toughness is not easy to take into account, so the user can only according to the specific processing objects and processing conditions in a number of carbide grades select the appropriate tool material , Which gives carbide tool selection and management of a lot of inconvenience. In order to further improve the comprehensive cutting performance of cemented carbide tool materials, the current research focus is mainly on the following aspects: refinement of grain, by refining the hard grain size, increase the grain surface area, The combination of strength, can make the carbide tool material strength and wear resistance are improved. When the WC grain size is reduced to below the sub-micron scale, the hardness, toughness, strength, wear resistance of the material can be improved, and the required temperature for complete densification can be reduced. The grain size of fine cemented carbide is about 1 ~ 1.5μm, and the grain size of ultrafine grain cemented carbide is less than 0.5μm. Ultrafine grain cemented carbide and composition of the same ordinary cement compared to the hardness can be increased above 2HRA, bending strength can be increased by 600 ~ 800MPa.
Ultra-fine grain cemented carbide has been more and more widely used, Kennametal company introduced the new brand KC5525, KC5510 cobalt content of up to 10%. Superfine WC grain as the matrix of cemented carbide, together with TiAlN PVD coating, can make the cutting edge in the cutting process has a high toughness, but also has a strong resistance to thermal deformation.
2.2 surface, the overall heat treatment and recycling heat treatment: the toughness of the cemented carbide surface nitriding, boron and other treatment, can effectively improve its surface wear resistance. The overall heat treatment of hard alloy with better wear resistance but less toughness can change the composition and structure of the binder phase in the material, reduce the adjacency of the WC hard phase, and improve the strength and toughness of the cemented carbide. The use of circulating heat treatment process to alleviate or eliminate the grain boundary stress, can improve the overall performance of cemented carbide materials.
2.3 Add rare metals: in the cemented carbide material added TaC, NbC and other rare metal carbide, the additive can be combined with the original hard phase WC to form a complex solid solution structure, thereby further strengthening the hard phase structure, but also from the To inhibit the hard phase grain growth, enhance the uniformity of tissue and so on, to improve the comprehensive performance of cemented carbide great benefit. In the ISO standard P, K, M class carbide grades, have this added Ta (Nb) C cemented carbide.
2.4 Add rare earth elements: in the carbide material to add a small amount of rare earth elements such as yttrium, can effectively improve the material toughness and bending strength, wear resistance has improved. This is because the rare earth element can strengthen the hard phase and bond phase, clean the grain boundary, and improve the wetting of the carbide solid solution to the binder phase. Add rare earth elements of the most suitable for rough processing, especially for wood and wood composite materials, cutting, rich in rare earth resources, such carbide The tool will have a wide application prospect. The current carbide tool material is moving in two directions, on the one hand, the universal type of application is more and more wide, more and more versatile; the other hand, the more specific brand-oriented, more adaptable The nature of the material being processed and the cutting conditions, so as to achieve improved cutting efficiency the goal of. Such as Kennametal's KU series (KU10T, KU25T, KU30T) carbide has a very wide range of versatility. Among them, KU10T and KU25T with high toughness and high wear resistance of the cemented carbide matrix, and with TiN + TiAlN composite PVD coating; and KU30T is used with excellent toughness of the cobalt-rich gradient of cemented carbide matrix, With TiN + TiCN + TiN composite CVD coating.
3 coated cemented carbide: on a hardened cemented carbide substrate, by CVD (Chemical Vapor Deposition), PVD (Physical Vapor Deposition), PVCD (Plasma Enhanced Chemical Vapor Deposition), HVOF (High Speed Thermal Coating) And other methods can be coated with a thin layer of wear-resistant metal compounds, such as TiN, TiC and other materials. TiC hardness Higher (HV3200), good wear resistance, so the coating thickness is generally 5 ~ 7μm. TiN hardness is low (HV1800 ~ 2100), and the binding force with the substrate is also low, but good thermal conductivity, high toughness, coating thickness of up to 8 ~ 12μm, the matrix toughness and coating wear resistance combined, Thereby improving the overall performance of carbide cutting tools. Coated carbide cutting tools with good wear resistance and heat resistance, especially for high-speed cutting, because of its high durability, versatility, for small quantities, multi-species of flexible automated processing, can effectively reduce the tool Times, improve processing efficiency. Coated carbide cutting tool resistant to crescent wear, tool edge and groove stability, chip breaking effect and other cutting performance is good, is conducive to the automatic control of the process. The matrix of the coated carbide cutting tool is passivated and refined, and the dimensional accuracy is high, which can meet the requirement of automatic machining for tool positioning accuracy. The above characteristics determine that the coated carbide cutting tools are particularly suitable for FMS (Flexible Manufacturing Systems) CIMS (computer integrated manufacturing system) and other automated processing equipment. However, the use of coating method has not been able to fundamentally solve the hard alloy matrix material toughness and impact resistance is poor.
It was found that the wear resistance of the saw blade front face was improved when the TiN-coated carbide saw blade was used. PVD coating woodworking saw blade cutting test proves that TiN coated WC cemented carbide saw blade (coated front teeth Surface) sawing the hard fiber board, the sawtooth wear is reduced. However, the CVD coating temperature is high, resulting in a brittle adhesion between the substrate and the coating Knot. In the coating residual stress and cutting heat, cutting force on the edge of the coating on the edge of the peel soon. Compared with the CVD method, PVD coating temperature is low, therefore, PVD coating of the tool can get a better coating structure and high coating hardness, tool edge sharpness also improved. In addition, PVD coating tool has a good anti-cracking ability. After the mid-1990s, the researchers studied the PVD coated carbide tool from the carbide size, binder content and coating materials. The particle sizes of the carbides were 0.8, 1.2, 1.5 and 1.7μm, respectively, and the corresponding cobalt contents were 3%, 4%, 6% and 10% respectively. The coating materials were TiN, TiN-Ti (C, N) And TiAlN2, corresponding to the coating thickness of 3.5μm, 5.5μm and 3μm, respectively, coated on the tool's rake face. The results show that the coating of the three coatings is peeling, but TiN and Ti (N, C, N) are much lighter than TiAlN2, and the wear resistance of fine particles and low cobalt content is increased by 10% ~ 30 %, But the high cobalt content of the tool coating but reduced wear resistance. The study also pointed out that the coating adhesion is the main reason for the coating peeling.
The "AL-TEC" coating series (eg IC900, IC903, IC908, IC910, etc.) of ISCAR's overall carbide end mill is also equipped with ultra-fine grain cemented carbide matrix with TiAlN PVD coating, Tool life increased by 150%. Valenite coated with 18μm thick TiCN / Al2O3 / TiC coating on the ultrafine grain cemented carbide substrate by MT-CVD. The flank was coated with TiC and the processing efficiency was higher than that of the uncoated cemented carbide (K05 ~ K10) tool increased by 50%. The company has developed a "yellow alumina composite coating" using medium temperature chemical coating technology, combined with the company's newly developed Durotec tooth-like transition layer technology, so that the yellow alumina coating and transition between the layers with excellent adhesion The nature of the At the same time, it has a good heat dissipation, and introduced the Steeltec LC215K and LC225K series blade. Steeltec LC215K cutting speed of up to 300m / min in cutting steel, blade life increased by 30%. and Steeltec LC225K on the basis of LC215K to further improve the toughness of the blade, so that the blade life on the basis of the original and extended by 30%.
Nano-structured coating technology in recent years, the rapid development of new coating technology, the coating material grain size is generally below 100nm, with good cutting performance. Japan's Sumitomo Electric Carbide Co., Ltd. introduced super-ZX coating (ACP200, ACP300, ACK300 and AC530U) carbide, using the overlap, the total number of layers of up to 1000 layers of ultra-thin TiAlN and AlCrN nano- The thickness of each coating is about 10nm, a significant increase in the coating surface hardness and oxidation resistance. Compared with the traditional TiAlN coating, the hardness of the super ZX coating is increased by 40% and the oxidation temperature is increased by 200 ℃, thus improving the tool processing efficiency by 1.5 times; under the same cutting conditions, the tool life is prolonged by 2 times.
In the coating, through the grain refinement technology to improve the coating surface finish, so that the coating surface is smooth, in order to improve the coating tool anti-friction, anti-adhesive ability is also a coating technology development direction. Japan's Mitsubishi Materials Co., Ltd. introduced UC6110 super-coated carbide tool material, the rake face to inhibit the growth of nano-TiCN and inhibition Crystalline growth of nano-Al2O3 composed of CVD coating, with high toughness and wear resistance, the outer surface of a layer of titanium compounds, so that the coating Smooth surface, flank surface for the ultra-smooth coating to ensure that the tool wear stability
Qualitative. Sumitomo Electric Carbide Co., Ltd. newly launched super-FF coated carbide materials (AC410K, AC610M, AC630M, ACP100, ACK200), in the special carbide substrate coated with ultra-fine grain TiCN, improved coating And the base of the binding force, and then coated with ultra-fine, ultra-smooth FF aluminum-based film, the surface hardness increased by 30%, 50% reduction in roughness, compared with ordinary cemented carbide, improve processing efficiency of 1.5 times , To extend the tool life more than 2 times.
Diamond has a very high hardness and excellent chemical stability, its wear resistance is 100 to 250 times the carbide, but also has the ability to resist strong acid and alkali, but toughness is poor. If the better toughness of the tool material Body, coated with a layer of high hardness, wear resistance and chemical inertness of the coating layer, so that the tool has a certain strength and toughness, but also has a good wear resistance and cutting performance, to meet the woodworking tool wear characteristics , Diamond coating is an ideal anti-wear means.
In the 1950s, the development of high temperature and high pressure synthetic diamond at the same time, people also explored low-pressure gas-phase synthetic diamond, but the deposition rate is very slow, because the low-pressure gas-phase synthesis of diamond in the metastable area of diamond and graphite phase stability zone , Graphite and amorphous carbon are easily precipitated. Therefore, the inhibition of the formation and removal of graphite and amorphous carbon has become the key to vapor deposition of diamond film. In the late 1980s, high-speed deposition methods such as industrial production and DC plasma injection have become the fastest method for the development of diamond thin film deposition in order to reduce the cost.
The cutting test of the particleboard by applying the CVD film to the front face of the carbide indexing blade (coating thickness: 20 μm) shows that the coating peeling is a fatal drawback. As long as the coating does not peel off, the tool wear is almost unchanged, always maintained at 40 ~ 50μm. Milling tests of medium-density fiberboards using diamond-coated cemented carbide index inserts show that diamond films have different degrees of peeling, but unbonded films play a "embankment" protection that reduces the wear of the base material and thus the tool Wear resistance increased by nearly 1 times.
With the improvement of the coating process and equipment, the diamond film and the substrate to further improve the adhesion, film stripping will be controlled. At present, has been used diamond-coated carbide material manufacturing processing to strengthen Plate of the tool, used to strengthen the surface of the laminate Al2O3 wear layer, the effect is good. However, CVD diamond polycrystalline thin film is very high purity, hardness (HV9000 ~ 10000) close to natural diamond, processability is very Poor, conventional machining or electrochemical corrosion is difficult to achieve its processing. So the diamond-coated cemented carbide material is suitable for manufacturing non-regrinding blade.
After 2000, the performance of diamond CVD coating tool has been further improved, the product covers the indexable tool and the overall hard Gold knife. Xiamen Golden Heron Special Materials Co., Ltd. "Green Cream" series of ultra-fine crystal diamond milling cutter coating average particle size is less than 1μm, the coating surface is smooth, the tool life can be increased more than 20 times. US SGS Tool Company's amorphous diamond (Amorphous Diamond) coated cutter, used to process the most wear characteristics of the material. The tool surface follows the tool The surface of the precise formation of crystal smooth, thickness of about 1μm amorphous diamond film, the most significant feature is the tool in a very high anti-wear (Surface hardness of 60 ~ 90GPa) at the same time, but also has a smooth tool surface, thus reducing the tool surface and the workpiece friction, and thus large The cutting temperature is reduced. Another feature of amorphous diamond coating is the tool base material is no special requirements, in any material of the knife With a substrate surface coating, the coating temperature is only 150 ℃. The life of the amorphous diamond tool is higher than that of the AlTiN coated carbide tool 6 times. In the assembly of woodworking cutter structure, in order to improve the blade clamping speed and positioning accuracy, is more used in the re-grinding blade or indexing knife sheet. Approximately 50% of the tool with the imported equipment is not re-grinding or indexing Milling cutter, such as edge banders, double-ended milling machines, CNC machining centers and other woodworking machinery assembly cutter. Therefore, the diamond-coated cemented carbide does not regain or index the blade in the woodworking knife. Therefore, the diamond-coated cemented carbide does not re-grind or index the blade in the woodworking tool With a broad application prospects.
4 Conclusion: Carbide tool material has become the current wood processing industry owners To cut the tool material, and in the future for a long period of time, Will still occupy an important position in wood cutting. With a variety of hard alloy performance improvement technology and continuous improvement of coating technology, cemented carbide Cutting tool material cutting performance will continue to improve, the wood processing industry to needle The wood and wood composite materials cutting characteristics, the application of various modifications and Coating technology to obtain new materials, rational selection of carbide materials and carbide cutting tools, to maximize the cutting of carbide cutting tools Performance, product quality and productivity.
Tungsten Carbide Wire Drawing Dies
The wire is passed through the holes of the tungsten carbide wire drawing dies so that the wire reaches the diameter of the process known as drawing. The principle of wire drawing is very simple, but from the mechanical point of view is quite complex. Although many theories and speculations have been published to explain the mechanics involved in wire drawing, many aspects have not been explained so far. Tungsten carbide wire drawing dies may be the simplest for tools that are used to deform metal in industry. The most basic form of wire drawing dies is a metal block with a tapered hole. People use this structure of the drawing die has been 500 years, although still based on the basic form, but in some aspects of the improvement.
In 1923, Karl Schroter found that the carbonaceous pigeon powder and diamond, iron or baht (10% weight) metal mixed together, after sintering can be made with low porosity, high hardness, high strength materials. He has produced a core that can be used to pull the pigeons and successfully applied it to the light manufacturing industry. Soon this new material has been widely used in non-ferrous metal wire industry. In the mid-1930s, the US steel wire manufacturing industry also commonly used this tungsten carbide dies.
Modern cemented carbide is similar to that produced by Scbroter. But after more than half a century of development and improvement, carbide manufacturing has produced a special alloy. The application of this alloy is very wide, and has resistance to wear, corrosion resistance, oxidation resistance, high toughness characteristics.
1.Carbide wire drawing die performance: Factors that affect the main performance of the carbide die are varied. The most important factors include the material being pulled, the section reduction rate of the material, the preheating of the wire, the lubrication of the @, the performance of the mold. It is believed that there are 49 reasons that affect the quality of wire drawing. These reasons can be divided into the following four categories. Of these, 19 are caused by molds. 14 reasons are caused by lubrication. Seven reasons are caused by the quality of the wire. Six reasons are caused by the drawing machine. Through the above analysis can be seen in the impact of drawing quality of the 48 reasons, drawing die accounted for nearly 40%. It can therefore be said that the quality of the drawing die is very important both for the moldmaker and for the wire drawing factory. In all cases, the performance of the drawing die is determined by the following three aspects. O mold material (core), @ mold sets, @ mold hole shape. Although the above three characteristics can be considered independent of each other. But in a specific case they are interrelated. Therefore, the characteristics of each aspect should be determined according to the proposed processing conditions.
2.Carbide performance: In essence, the cemented carbide is composed of very hard elements (carbonized pigeons) sandwiched between relatively soft base (drill) layers. Of the cemented carbide, the most important element is carbides. Which only a small amount of base metal film exists, filled with carbide particles of the gap. Since the thermal expansion properties of the carbides and the drill are different, they are subject to severe plasticity when the base metal film is bound to the hard particles. This will increase the strength of the matrix metal, and lead to the phenomenon of matrix metal embrittlement. This actually determines the performance of the cemented carbide. In practical applications, the amount of the drill conjugate is 3-25% by weight. (By volume of 5.5-37%), carbonized pigeon grain size of 1-lOμm. Since the carbonized pigeons are fine and the drilling content is low, the metal film of the conjugate is relatively thin. This makes the alloy with anti-deformation ability, high hardness characteristics. In addition, it also has a very high compressive strength, high elasticity and rigidity modulus, the shortcomings are relatively brittle. As a result of the addition of fine-grained carbides and 3% drill conjugates, the hardness of the cemented carbide rises from about HV900 of the general steel to above HV2000. At high temperatures, the cement can still guarantee its hardness. When the temperature reaches 600 ° C, the hardness of the cemented carbide can be the same as that of the high speed steel at room temperature, and the compressive strength of the hard metal is higher than that of any kind of man-made material, and it also has high elasticity and rigidity. Other properties of the alloy include its thermal conductivity is better than most of the steel and low coefficient of friction, these properties are very important for metal processing.
In the processing of wire drawing, if the anti-wear is the only factor, then the fine, low drilling content of cemented carbide may be widely used. From the fine wire to a variety of rolling rods in all the processing, this carbide can be a satisfactory effect. But the above situation is virtually non-existent. As with other metal forming operations, there are many other elements in the drawing process on its anti-wear properties have a significant impact. Such as mechanical stress, thermal stress, impact stress, fatigue and corrosive environments, play an important role in the wear mechanism, and therefore the effects of these factors must be taken into account. As with other materials, the toughness of the cemented carbide is improved as the hardness and wear resistance are reduced. It is therefore important that these relative properties be balanced when selecting the grade of cemented carbide.
In the analysis of wire drawing processing, in order to ensure the life of cemented carbide mold, it must be able to withstand the following various stresses. (Tensile stress) caused by deformation and friction (@), stress (in the extraction of the angular deformation zone), @ wear (by wire and drawing debris Caused). By drawing the fine 00.15mm high tensile steel wire and drawing 0s.smm rolling bar in the process of a variety of stress conditions, compared to be able to estimate the stress in the wire drawing processing limit. In drawing fine steel wire, the tensile and thermal stresses are low and the compressive stress and wear are high. The tensile fracture stress and thermal stress are quite severe when pulling the rod at 05 s mm, and the situation is further deteriorated as the bar cross section and surface accuracy change. If the grade of cemented carbide used can not withstand these stresses, the mold will fail. In the drawing of fine steel wire, such as wire diameter less than 0.75mm, can choose drilling content (by weight) for 3 - 6%, hardness of HV1700 fine particles of cemented carbide. In the drawing of rolling rods, should be drilled with jelly (by weight) for 12 - 14% of the fine particles of cemented carbide. Because this carbide can withstand the various stresses produced in the processing. The hardness of this material is only 60-70% of the low-drilling alloy, but the toughness is better. For the fine, low-drilling sturdy cement, the standard critical stress strength coefficient of 7MN / m-3'2. And the higher the drilling content, the better the toughness of the coefficient of cement can be increased to I8MN / m · l'2, which shows that even the same level of hard metal alloy, can not fully meet the two previously mentioned processing process. In order to achieve the best mold performance, you must select the appropriate carbide grade, and take measures to improve.
4. Mold structure: (1) mold sets, hard alloy compressive stress is particularly high. In general, its tensile load is poor (low-drilling alloy this is particularly prominent) so it must be drawing die core plus steel sets. In the drawing diameter of less than 0.75mm wire, because the tensile fracture stress is very low, so the core can be outside without steel. But in the drawing diameter greater than 0.75mm steel wire, the need to insert the core into the steel sleeve. In this way, it is necessary to press the cemented carbide core into the die sleeve with a compressive stress much higher than the tensile fracture stress. Tensile fracture stress is likely to have a bad effect on the service life of the core. Can be used to press the larger diameter diameter of the core into the steel sleeve on the mold than the useful life of a bad impact. You can use the press to the larger diameter diameter of the core into the steel sleeve on the smaller holes (the hole is pre-processed), can also be a simple hot pressing method of the core into the steel sleeve The material used in the steel sleeve is the normalized steel with a tensile strength of 4. In order to prevent the premature failure of the core, the core diameter of the interference size o.osmm. With the hammer method along the axis of the core all into the steel Fenzhong. In order to ensure that the hole and the outer diameter of the steel sleeve to achieve coaxial, the size of the steel sleeve must meet the requirements of precision. In addition, the outer diameter of the steel sleeve and mandrel must be finished and kept clean. So as to ensure that metal and metal contact, and to avoid the interface layer on the mold hole thermal dispersion obstacles.