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The application of laser heat treatment in the manufacture of stamping dies

in large-scale cold stamping dies, especially the heat treatment process of formed parts in forming dies (including deep drawing dies), is a difficult problem to solve, such as the covering parts of automobiles, the shell of stoves and the shell of household appliances, In the past stamping die manufacturing process, this kind of forming die parts usually adopt the following processes:

1. After the processing of the forming parts, they are polished and tested, and then they are put into the furnace as a whole. The process is as follows: cutting (or electrical machining) → grinding and polishing → assembly and test mold → heat treatment → delivery

2. After processing, the formed parts are polished and flame sprayed after mold test. The process is as follows: cutting (or electrical processing) → grinding and polishing → assembly and test mold → fire spraying → delivery

3. The whole formed parts are machined with rough machining allowance, and then polished and tested after heat treatment. The process is as follows: cutting (Rough Machining) → heat treatment → cutting (precision) → grinding and polishing → assembly of test mold → delivery so that the pipe filled with air will float on the sea in an arc

the above three process characteristics are shown in Table 1:

joint technology scheme of changing to PP, ABS and other materials

applicable types and advantages problems 1. The process is simple, suitable for parts with small size (forming depth is also shallow), and larger parts should be divided into blocks to reduce heat treatment deformation. 1. It is not applicable to parts with complex shape and large size, and it is difficult to solve the heat treatment deformation. 2. After splicing, it is difficult to eliminate the splicing line on the workpiece. 2

the process is simple and suitable for molds with low dimensional accuracy and small output. 1. The flame spraying process is difficult to control, and the hardness of the process fluctuates too much. 2. For plate parts (forming movable die or pressing plate), there is also heat treatment deformation. 3. The process is complex and suitable for molds with high requirements. 1. After heat treatment, CNC machining costs high and takes a long time. 2. Besides, there are restrictions on the heat treatment equipment and heat treatment process for large molds

although the above three processes have their own scope of application, they can not solve the process problems of complex parts of large molds, especially after nodular cast iron and alloy cast iron are increasingly widely used in large stamping molds, the heat treatment process problems of forming molds are becoming increasingly obvious

laser heat treatment can solve the above problems better

laser heat treatment is a method of surface treatment of metal by using high-power density laser beam to realize surface modification treatment such as phase transformation hardening and surface alloying, resulting in changes in surface composition, structure and performance that cannot be achieved by other surface quenching. Laser heat treatment is gradually accepted by the majority of mold manufacturers because of its wide applicability (applicable to medium carbon steel, medium carbon alloy steel and cast iron), stable processability (small hardness fluctuation, no deformation, no cracking) and almost unlimited by equipment. After instantaneous heating and rapid cooling of the material surface, laser heat treatment makes its surface harden to meet the use requirements. The process is as follows: cutting (electric machining) → grinding and polishing → assembly and test mold → laser surface treatment → polishing → delivery

for example, the drawing die of the barbecue oven chassis manufactured by our company for foreign customers, the die size is 1200*1000*600 (length * width * height), the material is QT700, and the forming part requires high hardness and wear resistance, which cannot be solved by ordinary heat treatment of such parts. If other materials are used and the mold is divided into blocks, the mold structure will be quite complex, the processing cycle will be at least doubled, and the problem of the splicing joint of the mold cannot be finally solved. After laser heat treatment, the above problems can be easily solved. Another example is the stamping die for the parts of the outdoor unit of split air conditioner, which is often manufactured by our company. There are many molding parts with the size of 800*400*60 (length * width * height). BASF showed the excellent performance of ecovio biodegradable agricultural film in the planting of corn, tomato and potato at the meeting. The material is 50 steel, such as the deep drawing molding die for the base plate and the deep drawing molding die for the top cover. In the past, such parts were processed and formed, and the surface was sprayed with fire, The process is unstable and the deformation quality of the parts is poor. This problem is also well solved after laser heat treatment. In other applications of molds, using ordinary medium carbon steel to replace expensive alloy tool steel and laser surface heat treatment of parts to replace integral furnace treatment of parts will also achieve better results in reducing energy consumption and mold manufacturing costs. (end)

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