Of influential factors Analysis on the service life of die for stamping die
1. stamping equipment is very important to the life of stamping die. Stamping equipment, high precision, good rigidity, stamping die life is greatly improved. For example: complex silicon steel sheet stamping die materials for the Crl2MoV, in the ordinary open press, the average recovery of 1-3 million times, and the use of new precision press, stamping die grinding life of up to 6~12 million times. Servo press through the actual test can improve more than 40 times the mold life Especially foot small gap or gapless! Stamping die, stamping die of hard alloy and precision stamping die must choose the press with high precision, good rigidity, otherwise, will reduce the die lif E, will be serious damage to chess.
2. mold design
(1) the precision of the guide mechanism of the mold. Accurate and reliable guide, to reduce the wear and tear of the working parts of the mold, to avoid the impact of convex and concave mold bite greatly, especially the no gap and small clearance punching die the, compound die and multi station progressive die is more effective. In order to improve the die life, we must correctly select the guide form and determine the accuracy of the guide mechanism according to the requirements of the working procedure and the accuracy of the parts. Under normal circumstances, the precision of the guide mechanism should be higher than that of the convex and concave die.
(2) die (convex concave die) cutting edge geometric parameters. The shape of convex, concave die, the fit clearance and the radius of fillet have great influence on the forming of stamping parts. For example, the fit clearance of the mold directly affects the quality of the blanking part and the die life. Accuracy requirements are higher, should select the smaller gap values otherwise, the gap can; be appropriately increased to improve the die life.
3. stamping process
(1) stamping parts of raw materials.
in actual production, due to the external pressure parts of the raw material thickness tolerance, material properties fluctuations and surface quality of the poor (such as rust or C) Lean (such as oil), will cause mold work parts wear intensifies, easy to collapse edge and other adverse consequences. Therefore, should pay attention to: (1) as far as possible the use of stamping process of raw materials, to reduce the stamping deformation force II before stamping should strictly; check the raw material grade, thickness and surface quality and raw material will be wiped clean, if necessary, should remove surface oxide and rust; (3) according to the stamping process and the type of raw material, if necessary, can arrange softening treatment and surface treatment, as well as the choice of appropriate lubricant and lubricating process.
(2) layout and lap.
irrational reciprocating feeding and th E method of sampling and too small to take the edge of the value of the mold will often cause sharp wear or convex concave die, bite. Therefore, in order to improve the processing quantity and quality requirements of the parts, and the gap between the mold and the mold, we must select the nesting method and the edge value in, order to improve the die life. The influence of
4 die material on the die life of
is the comprehensive reflection of the materials, chemical composition, microstructure hardness, and metallurgical quality. Different materials of the mold life is often different. To this end, the working parts of die material put forward two basic requirements: the use performance of the materials should be With high strength and high hardness (58~64HRC), and has high wear resistance and sufficient toughness heat treatment, deformation small, hot hardness II process performance is good.; Working parts of die manufacturing process is usually very complex. Therefore must have the adaptability to various processing processes, such as forging, machining quench, hardening, transparent, quenching crack sensitivity and grinding of. According to the material characteristics of stamping parts, production batch, precision requirements, select the good performance of the mold material, while taking into account the process and economic.
5 hot processing technology
practice has proved that the mold s hot working quality of " The mold s performance and service life "is very large. From the analysis of the cause of die failure statistics show that due to improper heat treatment caused by mold failure" accident "accounting for more than 40%. The quenching distortion and crack of the die working parts, the early fracture of the using process, are all related to the hot working process of the mould.
(1) forging process, which is an important part in the manufacturing process of the die working parts. For the mold of high alloy tool steel, usually put forward the requirements for the material distribution of carbide microstructure. In addition, it should be strictly controlled forging temperature range, the development of the correct heating specifi Cation, using the correct forging force method, as well as slow cooling after forging or timely annealing, etc..
(2) preparation of heat treatment. Should be considered the working parts of die materials and requirements of different were used preparatory annealing, normalizing and tempering heat treatment process to improve, the organization, to eliminate the forging blank tissue defects, improve the processing technology. High carbon alloy die steel after appropriate preparatory heat treatment can eliminate mesh secondary cementite or chain carbides the spheroidizing, of carbides, refinement and promote the distribution of carbide. This is conducive to ensuring the quality of quenching and tempering, improve the life of th E mold.
(3) quenching and tempering. This is the key link in the heat treatment of die and mould. If the quenching is heated, it will not only cause the workpiece to be more brittle, but also cause the deformation and crack in the cooling, which will seriously affect the life of the mold. Die quenching heating especially should pay attention to prevent oxidation and decarburization, should be strictly controlled heat treatment process norms, in conditions permit, the use of vacuum heat treatment. After quenching, it should be tempered in time and adopt different tempering process according to the technical requirements.
(4) stress relieving annealing. After rough machining, die working parts should be annealed With, the aim of eliminating the internal stress caused by rough machining, in order to avoid excessive deformation and crack. For the high precision of the mold, in the grinding or electrical processing after the need to go through the tempering process, is conducive to the stability of the mold precision, improve the service life.
6 processing surface quality of die
parts surface quality of the pros and cons of for mold wear resistance and fracture resistance ability and anti adhesion ability has a very close relationship, a direct impact on the service life of the die. Especially the surface roughness has great influence on the service life of the die, if the surface roughness value is too large. The work W Ill produce the phenomenon of stress concentration, and easy in its peak and valley between the cracks, the durability of the influence of die, affect the corrosion resistance of the workpiece surface will directly affect the service life and precision die therefore, we should pay attention to the following matters: the mold machining process must prevent grinding burn surface phenomenon should, strictly control the grinding process conditions and process methods (such as wheel hardness, grain size, cooling liquid, feed and other parameters should prevent the); surface of the mold work parts have the marks in the process. Interlayer, crack the impact of macro defects scar. These defects caused by stress concentration and a fracture to the Roots, resulting in early failure of the die; the grinding, lapping and polishing finishing and fine processing and obtain smaller surface roughness value, improve the mould service life.
7 surface hardening treatment of< p> to improve the performance and service life of the mold, mold work parts surface strengthening processing applications more and more widely. Commonly used surface strengthening treatment methods: liquid carbonitriding, ion nitriding, boronation and vanadium and electric spark strengthening, and chemical vapor deposition (CVD), physical gas phase deposition (PVD) and in a salt bath to workpiece surface coated carbide (TD). In addition, the use of high frequency quenching, hydraulic shot, peening And other surface strengthening treatment, so that the surface of the die working parts to generate compressive stress improve the, fatigue strength, which is conducive to the improvement of die life.
8 line cutting metamorphic layer of the control
die cutting edge of the use of wire cutting processing. Due to the thermal effect of the WEDM and electrolysis. Mold machining surface to produce a certain thickness of metamorphic layer caused decrease, surface hardness, micro cracks etc., resulting in line cutting processing die prone to early wear and tear, directly affect the mold blanking clearance of blade and ports to chipping, shorten the service life of the mold. Therefore, it should be chosen reasonably in The online cutting process, so as to minimize the depth of the metamorphic layer.
9 correct use and proper maintenance
in order to protect the normal production and improve the quality of stamping parts, reduce cost and prolong the service life of the die must be correct use of proper maintenance and conditioning, strict implementation of die "three check" system before use to check, process inspection and use of check), and do a good job of stamping die and maintenance work. Consists of molds do for the