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1、Volume precision forming mold design and manufacturing and developmentAuxiliary processing technologyIn the production process, improve die life is a complex comprehensive issues. All forging process, especially the net shape and approximate net form processing technologyMuch depends on the accuracy
2、 and quality, depending on the technology level of mould. Mould technology reflected in moulding design and manufacturing,And die life with the above two links in the outside, still and use the link. Improve die life is of great economic benefits, generally in the trial production mold tooling cost
3、accounting for stage production cost of about 25%, and finalize the design production is only 10%.Die early failure forms, many for the punch and die of fracture bore edge collapse, flash in the bridge chap, cavity occurred crack at the bottom.Many factors influence the life of die a wide range and
4、die design the life of die is based. Die design link is refers to the mould structure plan, setForming design and determine the cavity of the steel, mould hardness etc. Mould manufacturing process is to point to die making technology, heat treatment standard and surface treatment technology, etc.In
5、this paper, only from the mold design and die manufacturing two aspects to study and improve the life of die measures.1, the reasonable design precision volume forming a (fine forging)Die forgings should try to avoid with holes, narrow slot, Angle, shape should as far as possible is symmetrical, eve
6、n if they cant do axisymmetric, also hope to achieve,Under symmetrical or left, right symmetry. To design mold pulling out rake, avoid stress concentration and die forging units, increasing the pressure overcome eccentric loading and mould wear not equal defect.For forging die cavity edge and bottom
7、 fillet radius R, design should ensure forgings cavity is easily filled with the premise of amplification.If the fillet radius is too small, easily cavity edge in high temperature and high pressure of collapse, the serious will form the reversed cone, influence die forgings the mold.Such as the bott
8、om fillet radius R is too small and is not smooth transition, its easy to crack and will continue to expand.When the mould design should make full use of CAD system for products function 2 d and 3 d design, to ensure that the products to the unity of the original information and accuracy,Avoid man-m
9、ade errors, improve the mould design quality. Three-dimensional modelling product in forging process to reflect the product before comprehensive external shape,Timely find that the original design of the possible problems, at the same time, according to the product information, a computer design pro
10、cessing die-cavity roughing electrode, ready for the follow-up mold processing.The CAM technology can design according to the electrode accurately designated production mode. Adopt CNC milling machine (or processing center) processing electrode,Can ensure the machining precision of the electrode and
11、 reduce the time of the mould try, reduce scrap rate of the die and FanXiuLv, reduce the amount of fitter.For some complex shape, high accuracy of forgings,By the conventional die locksmith mould manufacturing methods guarantee certain size and shape using CAD/CAM technology in the complex forgings
12、precise dimensions description,The determination of reasonable parting surface to ensure accuracy molmerged, from the mould manufacturing this link to ensure product precision.CAD/CAM/CAE technology can be finite element analysis, the size of the key parts of the design is reasonable can provide mod
13、ification basis,Thus in for customers with high quality forgings, but also for the design of the customer provide the basis, strengthen the cooperation with the customers.Forming is the most important in the process of die forging work step, die forgings geometry is to rely on to ensure the forging
14、die, die forging process to fully consider all sorts of factors,Especially in production possible or has exposed problems, in the mold design measures should be taken to reduce the follow-up process of processing difficulty. According to this principle in prevention to reduce die forgings craze and
15、deformation, improving forgings qualified rate, can have pointed to take some countermeasures and measures. Such as forgings in certain parts of the machine and punching easily to affect the quality of products and deformation,But in the forging die design appropriate increase deformation parts of t
16、he machining allowance compensation, this is when the large deformation forging machine thin flange is more important.For some with stem and stem diameter relatively small forgings, in trimming and heat treatment process will produce regular geometric distortion,And with cold correction methods do n
17、ot or difficult to straightening. As a factory TS60 crankshaft,According to the practical experience and statistical data center in advance will be in a certain range of reverse migration direction deformation must advance the deformation for.2, the reasonable design forging processAt present, the g
18、eneral enterprise without sound technology lab, lack of process test conditions, which requires process program must be correct and a success. Especially after step into the market economy, the responsible person of the enterprise technical personnel can only request forging success, not to fail, th
19、is will give process design personnel brought the big difficult for process engineering is of high level to, but even with rich practical experience in the process are also hard to avoid can feel awkward, once mistakes can cause bigger loss.For trimming to the existing tear part in design flash slot
20、s can be forging when the thinning weak parts to the height of the bridge flash, and to decrease the cut when cut thickness of flash here. Such as S195 connecting rod, materials for 45 steel, after cold forging machine, a big head ZiBu due to section shape a small, thin material, often appear in tri
21、mming a near the children and the muscle tear, and scrap rate is high. If instead of waste can be after forging machine improve trimming quality, but because trimming production by die forging beat of limit, the efficiency is low. And in forging die design thinning here when the height of the bridge
22、 flash, reduce the flash cutting force, can greatly reduce trimming tear.For cold extrusion technology, must be the greatest degree softening and reduce blank when the deformation friction force, strictly control the deformation degree and each working procedure, deformation degree distribution.Gene
23、ral low carbon steel, carbon steel and low carbon steel alloy softening annealing process for: heating to 760 heat preservation 4 h,By 20 / h the cooling speed of cold to 680 heat preservation 3 h, again with 20 / h of the cooling speed to 640 after cooling furnace cooling to 350 Blackburn.Hardness
24、general can reach 125-155 HB.Less than 0.2% of the carbon content of carbon steel, steel the annealing can less than 120 HB hardness. The steel softening annealing then through roll light, acid, phosphate,Saponification besmear again after lard mix MoS-2 lubrication, may reduce the deformation load,
25、 effectively reduce the punch, molding cycle, joint body the fracture failure.The small deformation process of cold extrusion method can reduce the impact extrusion die under unit, not on the blank between production processes softening,Make die life prolonged. Some domestic manufacturers in the ext
26、rusion production of covet a will, reduce the extrusion process, although also can get samples (or product) make,But mould load is too big, prone to failure. This kind of practice is quick in cold extrusion technology once a boom and has failed to the development of the main technical reasons. The f
27、orging die CAE software, you can analyze the material flow, friction resistance and material filling overflow cavity,To help design personnel reasonably effective process design.3, reasonable structure of the die designThe mould structure design main consideration guidance accuracy reasonable, cutti
28、ng clearance appropriate, rigid, consider using combined mold as far as possible.Formwork should have a good rigidity, do not only meet the required strength, template shoulds not be too thin, and where possible to add thick, even thickening 50%.Progressive die unfavorable use only 2 root guide pin
29、orientation, should try to do four root guide pin orientation, this guide good performance. Because of increased stiffness, ensure the convex,Concave die gap even, make sure the punch and concave die wont happen touch cut phenomenon.Floating mode can avoid press mold to handle the bad influence of g
30、uidance accuracy. The punch should clamping reliable,When the check assembly to punch or concave die on the vertical axis of the level and up and down between the underside of the parallel degree.In the cold extrusion, punch and concave die of hardness to the right, to give full play to the fortitud
31、e to prolong life processing of potential.If W6Mo5Cr4V2 steel cold extrusion of the punch, when hardness 60 HRC frequency when normal use, life for 3000 3500.But if by that experience low hardness, plastic life must extend will greatly disappointed, when hardness for 57 58 HRC extrusion workpiece,Th
32、e work of the punch with will be upsetting. A factory detection 1 a punch die extrusion after work with size found, upsetting a large increase from 0.01 to 0.04 mm.For hot press concave die cannot apply mechanically cold extrusion touch experience, when the three Cr2W8V steel hot press concave die f
33、rom the hardness value 40 HRC to 37 to 38 HRC,Service life from 1000 2000 times increased to 6000 8000 times. According to experience, different forging equipment for the hardness of forging die forging requirements are different, and even in the same kind of forging equipment of die forging, forgin
34、g different products to mold hardness requirement is not the same. In forging flash resection, punch bottom should as far as possible with the hollows of forgings coincide with the surface. Such as cutters die forging a keen flash,Cut flash at the bottom of the punch hollow to and cutters arc of the
35、 handle fit, or in the cut in the process of flash, flash to cut the punch forgings to one side to flip, make the punch and concave die damage. Usually, the cutting clearance amplifier can extend life cut flash mode.4, reasonable selecting mould materialAccording to the working conditions and produc
36、tion mold batch of material itself and strong performance to selecting mould material, should as far as possible choose quality good steel.According to the information of the mould are being manufactured for high, but the material cost is only the price of general mold by 6% 20%. To die material to
37、a test, module should comply with the supply agreement, the chemical composition of the module to comply with the relevant provisions of the international. Only in the case that module qualified to forging. Large module (100 kg above) by electric steel slag re-melting H13 make sure internal quality,
38、To avoid possible ingredients segregation, impurities such as internal defects exceed bid. To make use of the ultrasonic testing of nondestructive testing technology such as check to ensure that each forgings internal quality is good, avoid possible metallurgy defects, will eliminate waste as soon a
39、s possible.5 and reasonable establishing the steel forging normsAccording to the carbide segregation to the influence of the die life, must limit the inhomogeneity of carbide degree of precision mould and load the slender punch,Must choose good toughness of high strength steel mold, carbide not unif
40、ormity should be controlled for not more than 3 grade. Cr12 steel carbide not uniformity level 3 than level 5 durability improve 1 times above. Roll silk die of carbide not uniformity for 5 6 grade most roll silk 2000 pieces, and not the homogeneous degree to improve carbide at level 1 2 can roll si
41、lk 550000 pieces. If carbide segregation serious, may cause overheat, burning, craze, collapse collapse, tensile blade, and early failure. Ribbon, mesh, large particles and large firing the carbon that is made of mould performance anisotropic, horizontal low intensity, and plastic also poor.Accordin
42、g to the micro hardness measurement results, carbide normal distribution place for 740 760 HV, carbide concentration point is 920 940 HV,Carbide in 610 670 rare for HV, rare place in carbide to excessive tempering, hardness and strength is reduced, carbide FuJiOu often lack for tempering,Brittleness
43、 is big, and lead to mould upsetting or break.Through the forging can effectively improve the tool steel carbide segregation, generally after forging can reduce carbide segregation level 2, for a maximum of 3 grade. Had better use axial,Radial repeated heading pull (cross heading pull law), it is up
44、setting the raw materials in the section after two perpendicular direction heading out again and again, and finally to along the axial or horizontal forging into, repeat this process is called double cross heading pull out, repeat many times for many times that the dui pull out. For 50 mm diameter l
45、ess than or equal to the high alloy steel, the carbide not uniformity in general than level 4, can meet the general mold use requirement.6, rational selection of heat treatment processHeat treatment is not to die early failure of the important reasons, according to a factory statistics, its accounts
46、 for about 35% of the mould early failure factors.Heat treatment including forging die after the annealing, rough machining of high temperature tempering or low temperature after the tempering, finish machining the quenching and tempering after, edm, line cutting later to stress low temperature firi
47、ng back. Only cold heat processing is very good and cooperate with each other, to ensure good die life. The mold cavity and thin wall when the need to normal quenching temperature the ceiling, so that residual austenitic rises, make the mold from swell.Due to rapid heating heating time is short, to
48、reduce the decarburization oxidation, small grains of carbon steel large-scale die quenching little deformation. For high speed steel paper with low quenching, high back to technology is more good, quenching temperature is low, tempering the higher temperature, can greatly improve the toughness, alt
49、hough rigidity decrease, but to improve for broken or fatigue damage of die life is very effective. Usually Cr12MoV harden steel heating temperature of 1000 , the oil cold, then 220 tempering. As in the heat treatment to advance a time before heat treatment, heat to 1100 is the heat preservation, oil cold, 700 high temperature tempering, then die life can be greatly improved. We in the early 70 s for 3 Cr2W