Factors affecting mold life
Release time:
2024-03-29 15:02
Source:
(1) The influence of mold structure
Mold structure on the mold stress state has a great impact, a reasonable mold structure can make the mold work uniform force, not easy to bias load, stress concentration is small. There are many kinds of molds, the form of a great difference, the working environment is not the same, the following from a few common aspects to be discussed.
(1) corner radius corner radius is divided into outer (convex) corner radius and inner (concave) corner radius. The size of the work part of the corner radius, not only on the forming process and the quality of formed parts have an impact, but also on the failure of the mold form and life impact.
(2) Mold structure form
① whole mold and insert mold whole mold concave corner radius is easy to cause stress concentration, and thus cause cracking.
② mold guidance using guide device mold, can ensure the accuracy of the mutual position of the relevant parts in the mold, increase the mold resistance to bending, anti-deviation load capacity, to avoid uneven wear and tear of the mold.
(2) the impact of the working conditions of the mold
1）Material and temperature of molded parts
(1) material forming parts of the material has metal and non-metal. Generally speaking, non-metallic materials, low strength, the required forming force is small, mold force is small, mold life is high. Therefore, metal molding die than non-metallic mold life is low.
② temperature in forming high-temperature workpiece, the mold due to accept heat and warming, with the rise in temperature, the strength of the mold decreases, easy to produce plastic deformation. At the same time, the mold with the workpiece contact surface and non-contact surface temperature difference is very large, resulting in temperature stress in the mold.
(2) Equipment characteristics
① precision and rigidity of the equipment mold forming the workpiece force is provided by the equipment, in the forming process, the equipment will produce elastic deformation due to force.
② speed equipment on the mold and the workpiece force is gradually increased over time, the speed of the equipment affects the process of force application. The higher the speed of the equipment, the greater the impact of the mold within a unit of time (large impulse); the shorter the time, the impact energy can not pass and release, easy to concentrate in the local area, resulting in local stresses exceeding the yield stress of the mold material or fracture strength. Therefore, the higher the speed of the equipment, the easier the mold fracture or plastic deformation failure.
3) Lubrication
Lubrication of the mold and the relative movement of the blank surface, can reduce the direct contact between the mold and the blank, reduce wear and tear, reduce the forming force. At the same time, the lubricant can also hinder the blank to a certain extent to the mold heat transfer, reduce the mold temperature, to improve the life of the mold are beneficial.
(3) the impact of mold material properties
The performance of the mold material has a greater impact on the life of the mold, these properties include: strength, impact toughness, wear resistance, corrosion resistance, hardness, thermal stability and heat fatigue.
(4) The impact of the mold manufacturing process
(1) in the module forging, module heating and cooling brought about by the internal and external temperature difference will produce temperature difference stress; upsetting, punching and reaming process such as improper selection of technical parameters easy to make the forging billet cracking. In addition, when the forging ratio exceeds a certain value, due to the formation of fibrous tissue, lateral mechanical properties decline sharply, resulting in anisotropy.
(2) in the die of electrical processing, there will be different degrees of metamorphic layer, in addition to the local sudden heat and cold, but also easy to form residual stress and cracking.
3）Heat treatment of mold
Mold heat treatment is arranged in the module forging, rough machining, almost the final process of mold processing. The selection of mold materials and heat treatment process to determine the performance of the mold has a great impact!
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