Purifier Chrome

Application Of Steel-Bonded Carbide

    Bonded Carbide is a kind of steel for adhesives, in order to make hard carbide phase and the manufacturing of cemented carbide powder metallurgy materials, the performance of the general range of alloy tool steel and ordinary between carbide. Many pieces of steel bonded carbide sintered blanks after annealing can be an ordinary cutting, after quenching and tempering after the metal-ceramic alloy similar to the hardness and good wear resistance, but also can be welding and forging, and with a wear-resistant, anti-oxidation properties.

Despite the high cost of these materials, molding more difficult, however, after use can significantly increase the die service life, in mass production with good technical and economic results. Thus, in a wider scope and deeper to promote it, to the mold industry has very important significance. Here are the steel-bonded cemented carbide drawing die in the self-help device in the specific application.

    1, the original production problems

    Mine self-rescuer under the shell size shown in Figure 1, material for the 08A1, material thickness 0.8mm, high-volume production quantities. Shape of the workpiece be drawing twice. Of the original mold and die materials are Crl2, the equipment used for the general double-action press. Production, molds used for a period of time, the workpiece surface, there will be a clear scratch marks, seriously affected the quality of appearance.

    Observed: The first deep-drawing process after the end of the outer surface of semi-finished products has a small scratch, the second after drawing abrasions, scratches markedly increased, and the working surface of the die wear and tear of serious, often the workpiece material adhesion. After the repair mode can only be drawing thousands of shells. To solve this problem, the factory has tried to improve the precision mold manufacturing, reduce the surface roughness value, and even polished, chrome, it is still fundamentally solve the surface strain, the problem of short die life.

     2, process analysis

     Through the analysis shows that: the original mold structure, die work of the structural parameters and the lubrication of deep drawing process is basically rational manner, workpiece produce abrasions, scratches and is processed primarily to mold the friction between the billet surface, the contact surface related to the situation.

     On the one hand, drawing the process of billet and die surface of contact will have a lot of pressure, this time, a number of friction and boundary lubrication area without lubricant added, it will cause a sharp deterioration in the state where the friction on the other hand , 08A1 is a soft material, if the mold hardness is low, it will increase production of hot-deformation heat treatment despite the hardness of Cr12 has been high, but in this case a continuous high-volume deep-drawing was still inadequate. For the above reasons led to the mold used for a period of time, a sharp rise in the temperature of friction surface) at high temperatures, the local friction of metal cladding bonding, so that semi-finished products first appeared minor scrapes and scratches.

    At this point, if the failure to make timely repair mode, the former working procedure generated abrasions and minor scratches in the next one is bound to increase die wear and tear process in turn increased the drawing force, part wall of the tensile stress and friction, so that the friction surface temperature increased further, thus once again rise to metal deposition, increased production of friction bonding, leading to a vicious circle, deposition more serious, scratches more apparent.

     Based on the above analysis, taking into account the steel-bonded cemented carbide GT35 has a high hardness (quenching hardness of up to 69-73HRC), high wear resistance, heat deformation small, and good machining characteristics, etc., to meet in this case drawing of the the use and processing technology requirements, so we will die material Cr12 into steel bonded carbide GT35.

    3, mold manufacturing Attention

    To give full play to the fine steel-bonded cemented carbide GT35 features a very high camphor life. Mounting structure using Au-chang

    When the first drawing die sets is expected to play a role in pressure, so use good wear resistance, high hardness, heat treatment for the inlay sets Cr12. The second drawing, the blank part of the circle in the alloy, so wash with 45 steel as an inlay material investigation.

    (1) Die Cutting Process of Steel-bonded cemented carbide GT35 annealing in good condition, hardness is generally 39-46HRC. Can be cars, milling, planing, boring, filing, tapping and so on. Cutting process, the cutting speed should not be too high, feed rate should not be too large, the amount of back knife should not be too small to eat. Practice has proved that: cutting speed is too high, excessive feed back and knife to eat the amount is too small, then the blade with the workpiece friction, heat large, will increase the amount of blade wear, in addition, due to the blade with the workpiece surface of extruded , processing, shiny surface and harden, which makes it more difficult to continue cutting, the actual process can be slow the first try, and then gradually increase speed.

    (3) The working part of the die machining steel bonded carbide die machined by wire cutting to the hole cut, leaving a certain degree of grinding margin. The second drawing die 45 slope with the EDM forming.

    (4) The die assembly of die sleeve and die hot pressing assembly, pre-load through the die set diameter and alloy ring diameter interference fit to obtain. Mold design, assembly should be based on the temperature and the need to pre-load forces accurately calculate the size of the die sets of diameter sizes. Die sets of heated box-type furnace in the heat treatment carried out. When the temperature rises to 350 ℃ when you start to time, insulation 2h. At the same time put in the bottom die plate with a grind with a good heating, so as to avoid cooling too quickly came out and affect assembly.

    (5) Other considerations should be smooth and reliable mold-oriented. The thickness of the upper and lower mold plates should be appropriately increased, in order to enhance rigidity and stability of the mold, and reduce vibration.

     Mold processing finished, you should use a high hardness of diamond and diamond polishing paste oilstone grinding face, to ensure that the surface roughness, reducing the processing power of the metamorphic layer, give full play to the high steel bonded carbide hardness, high wear resistance.

    4 Practice has proved that the use of steel-bonded cemented carbide GT35 self-help devices manufactured under the shell drawing die, not only guarantees the quality of the product, but also greatly enhance the life of the mold, and achieved good economic results.
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