October 31, 2017

Influence of manufacturing process on service life of carbide punch dies

Carbide punch diesis a special process equipment which is used to process materials (metal or nonmetal) into parts (or semi-finished products) in cold stamping process, which is called cold stamping die (commonly known as cold carbide dies). Stamping is a pressure processing method to obtain the required parts by pressing the material at the room temperature with the die installed on the press so that it can produce separation or plastic deformation. This paper introduces the selection of stamping die material and the influence of die manufacturing process on the service life of carbide punch dies.


Selection of blanking die materials


The blanking die material should consider batch workpiece production, if the volume is not high there is no need to select the life of die material; should also consider washed workpiece materials, different materials for the mould materials are also different. For punching die, wear resistance is an important factor in determining the die life, depends on the wear resistance steel carbide in hard phase condition and matrix hardness, both higher hardness, the more the number of carbide is better wear resistance. The inferior and common stamping die steel wear resistance are carbon tool steel alloy tool steel - steel - steel - Gao Tangao matrix of high speed steel - steel bonded carbide - tungsten carbide.


In addition, the influence of the thickness, shape, size and precision requirement of the workpiece on the choice of the mould material must be considered.


1. traditional die steel, for a long time, the domestic sheet blanking die steel for T10A, CrWMn, 9Mn2V, Cr12 and Cr12MoV, etc..

Among them, T10A is carbon tool steel, with certain strength and toughness. But the wear resistance is not high, the quenching is easy to deformation and cracking, hardenability is poor, only suitable for the workpiece shape is simple, small size, small number of blanking die.

The heat treatment process of T10A carbon tool steel is: 760~810 degree of water or oil quenching, tempering at 160~180, hardness 59~62HRC.

CrWMn and 9Mn2V are high carbon and low alloy steel. Quenching is easy to operate, hardenability is better than carbide punch dies, deformation is easy to control. But the wear resistance and toughness are still low, and it is applied to the medium batch, the workpiece shape is more complex blanking die. The heat treatment process of CrWMn steel is as follows: quenching temperature 820~840, oil cooling, tempering temperature 200, hardness 60~62HRC. The heat treatment process of 9Mn2V steel is as follows: quenching temperature 780~820, oil cooling, tempering temperature 150~200, air cooling, hardness 60~62HRC. Attention should be paid to tempering brittleness and significant volume expansion at tempering temperature range of 200~300.

Cr12 and Cr12MoV for high carbon high chromium steel, high wear resistance, quenching deformation is small, good hardenability, mold used for mass production, such as carbide punch dies. However, the carbide of this kind of steel is uneven, easy to produce carbide segregation, and it is easy to break or break during cutting. Among them, carbon content of Cr12 is higher, carbide distribution is more serious than Cr12MoV, brittleness is greater.

Require the use of the heat treatment process of Cr12 steel depends on the choice of the mold, when the mold requirements relatively small deformation and toughness, the low temperature quenching and tempering (Cr12 950~980 DEG C for quenching, tempering; 150~200 C Cr12MoV 1020~1050 C 180~200 C quenching, tempering). If you want to improve the temperature of the mold, improve its hardenability and hardness, can be made of high temperature quenching and tempering (Cr12 1000~1100 DEG C for quenching, tempering; 480~500 C Cr12MoV 1110~1140 C 500~520 C quenching, tempering).

High chromium steel is temper brittleness in the 275~375 C region should be avoided.

Posted by: hannahgwendolyn at 09:54 AM | No Comments | Add Comment
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October 27, 2017

Black tungsten is the most important mineral raw material for tungsten smelting

Black tungsten is the main ore that is refined tungsten, also known as tungsten manganese iron ore. Because of the different proportions of ferrotungstate and manganese tungstate, if the iron content is higher, some of them are called tungstenite, and some of them are called tungsten manganese. The black tungsten deposit is brown to black and has metallic or semi-metallic luster. It is commonly found in granite and quartzite. The south of China's jiangxi province, the eastern part of hunan province and the north of guangdong province are the world's most famous areas of the black tungsten mine. The black tungsten deposit is produced in high temperature hydrothermal quartz vein. China's southern jiangxi, eastern hunan, and northern guangdong province are the world famous black tungsten mines. Other major areas include Siberia, myanmar, Thailand, Australia and Bolivia. it is the most important mineral material for tungsten refining.

The black tungsten carbideand tungsten manganese ore are mainly produced in the quartz vein of high temperature hydrothermal quartz and its yunying lithosphere. Veins often exist in the granite intrusion at the top or near contact zone of surrounding rock, mineral association of cassiterite, molybdenite, bismuthinite, pyrite, chalcopyrite, arsenopyrite, topaz, beryl, tourmaline, etc. Tungsten and manganese minerals can also be found in medium and low temperature hydrothermal veins.

Brittle wolframite and easy smash, produced in the process of development and utilization of a large number of black tungsten fine mud, according to a 2010 survey data, at present our country's tungsten ore concentrator fine clay content is between 3% and 17% of total capacity, metal content accounts for about 5% of the total amount of metal - 5% every year in China alone, nearly 245000 tons of tungsten content of fine clay, tungsten fine clay mineral average job recovery is only about 40%.

Before the application of new technology, the fine tungsten mud concentrator has been using shaking table re-election + blanket cloth trough LiuCheng recycling black tungsten fine mud of tungsten, tungsten concentrate containing WO3 9%, the average recovery was 40%, including S 10%, including the As 5%, because of the low grade and impurity to exceed bid, is difficult to direct sales.

Aiming at these problems, study the pulsating high gradient magnetic separation - suspension vibration separator enrichment of preclassification table re-election joint process new technology of recovery of fine mud black tungsten, greatly improved the black tungsten fine clay ore dressing indexes. The technology industry in tungsten successful implementation, built YiTiao annual capacity of 45000 tons of production lines, since 2013 has remained steady production, concentration of tungsten concentrate containing WO3 increased by 20%, recovery rate increased by 40%, fine puree concentrate contains S reduced to < 1%, As low As < 0.5%, tungsten concentrate nearly 130 tons per year. After the implementation of the new technology, the economic benefit of the new technology was 213.987 million yuan in the two and a half years since 2013. Experts believe that in the results of the overall technology in the field of black tungsten fine clay mineral reached the domestic leading level, successfully solving the practical problems of enterprise production, has the very good reference to domestic similar enterprises.

Posted by: hannahgwendolyn at 09:45 AM | No Comments | Add Comment
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October 20, 2017

there are special considerations when carbide milling cutters is cutting

carbide milling cutter is made of materials refers to the use of cemented carbide carbide cutter. Understand the need to know what istungsten carbide, hard alloy with high hardness of refractory metal carbides (WC, TiC) micron powder as the main ingredient, with cobalt or nickel (Co) (Ni), molybdenum (Mo) as the binder, powder metallurgy products in vacuum furnace or hydrogen reduction furnace in sintering.

In the three edge milling cutter, milling or some surface milling, cutting force in different directions. Surface milling, milling cutter in the workpiece just outside the cutting force in the direction of more special attention should be paid. When the milling, the cutting force will work pressure to the work table, cutting force inverse milling workpiece and left the table.

As the cutting effect of progressive milling is the best, milling is usually preferred. Only when there is a screw gap in the machine tool or a problem that can not be solved by forward milling, reverse milling is taken into account

In an ideal situation, the diameter of the cutter should be higher than the width of the workpiece, cutter axis and workpiece center line should always leave some distance. When the tool is placed on the center of cutting, easy to produce burr. Continuous cutting edges entering and withdrawing from cutting when the radial cutting force direction will change, and it may damage the spindle vibration the blade may be broken, the surface will be very rough, with slightly off center, cutting force direction will not change anymore -- cutter will get a pre load. We can put the center of milling to drive on the road.

Every time into the carbide cutting cutter, cutting edges are subjected to impact load, transverse load depends on the size of the chip, workpiece material and cutting type. Cutting, between the cutting edge and the workpiece is correctly occlusion is an important direction.

When the cutter axis is completely on the lateral width of the workpiece, the impact force at the cut in is borne by the outer blade tip, this will mean that the impact load from the initial part of the most sensitive tool to bear. The last and carbide cutter to the tip off the workpiece, that is to say from the beginning to leave the cutting blade, cutting force effect has been on the outside of the tip, until the impact unloading so far. When the center line of the cutter is located in the edge line, when the chip thickness reaches the maximum when the blade from the cutting load, reaches the maximum at the cutting impact. When carbidemilling cuttersaxis line is located within the width of the workpiece, the initial impact load when starting position the distance along the cutting edge by far the most sensitive point in the back and bear, knife blade smooth exit cutting.

For each blade, when to exit when cutting off the workpiece cutting edge way is important. The remaining close when retracting materials may be much reduced. When the blade gap chip from the workpiece along the blade rake surface will produce an instantaneous tensile force and burrs on the workpiece. This often produces the tensile force in dangerous situations endangering the cutting edge.

Posted by: hannahgwendolyn at 09:35 AM | No Comments | Add Comment
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October 10, 2017

China's carbide cutting tools need to adjust the industrial structure


In the new world economic integration wave, the acceleration of global manufacturing to the mainland of China has been a trend, and China will gradually develop into a world-class manufacturing base. The obvious advantage of guangdong, especially the pearl river delta region, we will develop into a global mold production center within ten years. The cutting tool market is in a period of rapid development, and simple tools are being replaced by more and more multifunctional tools. In the production of the future, the user will be on the research and development of cutting tools is put forward higher request,itis not only in the field of cutting tool materials and surface coating technology, but also for cutting tool production technology will have more strict requirements.


Carbide can also be used to make the drilling tools and mining tools, drilling tools, measuring gage, wear-resistant parts, metal abrasive, cylinder liner, precision bearings, nozzle, hardware mold (such as wire drawing die, bolt moulds, nut moulds, as well as a variety of fasteners, mold, excellent performance of cemented carbide gradually replaced the previous steel mold).

The worldwide demand for carbide cutting tools is growing. Among them,the growth of European and north American countries is stable, especially in eastern European countries. Asian markets have recovered slightly and the market potential is large, and the market of Latin American countries has grown significantly, especially in Mexico. Cutting tool market demand growth slowly, mainly because of cemented carbide tool life increased, then there is the user request, for the whole manufacturing process instead of many machine tools and cutting tools. As well as the use of multi-function knives, a lot of simple cutting tools have been replaced.


According to statistics, the production of tungsten carbidecutter in China is increasing year by year, making carbidecutting tool material enter the development era represented by tungsten carbide. According to the current situation of China market, the market share of domestic carbide turning tool is lower than that of imported tools, so it is urgent to adjust the industry structure.

Our country has entered the stage of manufacturing industry to upgrade, the state planning to high-end equipment manufacturing and information industry into the pillar industry of national economy, which will greatly promote the carbide blade, cutting tool market demand, the cemented carbide industry promising prospects.

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