During the forming process of automobile stamping parts, the problem of surface strain is easy to occur. If the production continues, the surface of the mold will also be strained, and the produced parts are easy to be scrapped or reworked, which not only increases the cost of a single piece, It also increases the cost of mold maintenance. The usual way to solve the problem is to stop the machine to grind and polish the surface of the mold, but it is easy to cause the gap between the convex and concave molds of the mold to become larger, and the quality of the product is reduced. Therefore, a systematic analysis is carried out on how to solve the problem of workpiece strain, and one of the solutions, TD coating treatment (thermal diffusion carbide coating treatment) on the surface of the mold, is emphatically explained in detail. After the TD coating treatment of the forming die, the problem of strain defects of the stamping parts is improved, the product quality is guaranteed, and the smooth operation of the product is ensured.
Key words: stamping part strain; die material; surface TD coating treatment.
With the vigorous development of my country's automobile industry and the enhancement of consumers' awareness of safety and environmental protection, consumers in my country have higher and higher requirements for the cost performance of automobiles, which promotes the development of high-strength and lightweight stamping materials in the automobile industry. With the increasing use of high-strength plates for stamping materials, regardless of thick plates or high-strength steel plates, the stamping or rolling forming dies are subject to extremely high forming stress, and the problem of surface strain on the workpiece is even more serious, so automobiles The mold industry is facing higher challenges, and how to solve the problem of parts strain has become an important issue in the mold industry.
1. Stamping parts strain
1.1 The essence of the strain of stamping parts is the result of the local adhesion (or welding, occlusion) of the workpiece and the surface of the mold. Practice has shown that, in the absence of other protective measures, when the forming force of a mold made of steel material for forming steel parts is large, no matter how the mold is heat treated or how high the hardness of the fire is, the problem of strain can not be solved. avoid.
Figure 1 shows the main body structure of the tunnel in the front floor of a vehicle. The tensile strength of this material is above 300MPa, the tensile depth is above 180mm, and the draft angle is 90 and 120. The hardness of the convex and concave molds of this part mold reaches 55 to 60 HRC. In the actual production process, there is a phenomenon of strain.
The emergence of strain problems will also bring the following problems:
1: It is difficult to meet the requirements of pneumatic wrench batch continuous production, reducing production efficiency and increasing labor intensity;
2: Reduce the life of the mold, and the consistency of the size of the processed parts becomes worse;
3: It affects the appearance of the parts and reduces the quality of the parts.
1.2 Common solutions to strain problems
To solve or improve the problem of strain, there are many methods. The basic principle is that the properties of the friction pair between the mold and the machined part must be changed. The friction pair is replaced by a material that is not easy to stick. The specific method can be:
2: Surface treatment (such as phosphating) of the raw materials of the processed parts;
3: Add a layer of other substances between the mold and the workpiece to be processed.
Through the above methods to achieve the purpose of separating the workpiece from the mold (such as increasing lubrication or adding special lubrication or adding a layer of PVC and other materials). By summarizing the process of solving the problem of the rear door chain reinforcement plate strain and comparing it with other companies, it is found that: in general, the forming mold is treated with TD coating (thermal diffusion carbide coating (Thermal Diff i sion Carbide coating). Coating Process), can fundamentally solve the problem of strain of the workpiece. This technology is also one of the best ways to solve this problem at present, coupled with the extremely high wear resistance of the TD coating, it can increase the life of the mold several times. To dozens of times. A large number of practices have proved that the application of TD coating treatment technology can greatly improve production efficiency, improve product quality and reduce production costs.
2. TD coating treatment technology
TD coating treatment is the abbreviation of Thermal Diffusion Carbide Coat ing Process (Thermal Diff i sion Carb i d e Coat ing Process), English abbreviation TD coating, also known as molten salt metal infiltration in my country.
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