Metal mold surface super hardening treatment technology

Metal mold surface super hardening treatment technology

I. Introduction of diffusion metal carbide coating technology

1. Technical introduction

Diffusion metal carbide coating technology is to place the workpiece in a special medium and diffuse on the surface of the workpiece to form a layer of metal carbide of several micrometers to several tens of micrometers. The carbide layer has a very high hardness, HV can reach 1600~3000 (determined by the type of carbide), in addition, the carbide track layer is metallurgically combined with the substrate, does not affect the surface finish of the workpiece, and has extremely high wear resistance and resistance. The properties of bite (bonding) and corrosion resistance can greatly improve the service life of tooling and mechanical parts.

2. Comparison with related technologies

The method of forming a superhard compound film layer on the surface of the workpiece is an effective and economical method for greatly improving the wear resistance, seizure resistance (anti-adhesion), corrosion resistance and the like, thereby greatly improving the service life thereof. At present, the surface hardening treatment methods of the workpiece mainly include physical vapor deposition (PVD), chemical vapor deposition (CVD), physical chemical vapor deposition (PCVD), and diffusion metal carbide formation technology. Among them, the PVD method has a low deposition temperature. The advantage of small deformation of the workpiece, but due to the poor bonding force between the film layer and the substrate, the winding properties of the process are not good, and it is often difficult to exert the performance advantages of the super-hard compound film layer. The CVD method has the advantages of good film-based bonding force and good coating quality, but for a large number of steel materials, the subsequent matrix hardening treatment is troublesome, and the film layer is easily damaged. Therefore, its application is mainly concentrated on materials such as cemented carbide. The deposition temperature of PCVD method is low, the film-based bonding force and the process winding property are both improved compared with the PVD method. However, compared with the diffusion method, the film-based bonding force still has a large gap, and the PCVD method is still a plasma film formation. Although the winding properties are improved compared to the PVD method, they cannot be eliminated.

The metal carbide coating formed by the diffusion metal carbide coating technology forms a metallurgical bond with the matrix, and has a film-based bonding force unmatched by PVD and PCVD. Therefore, the technology can truly exert the performance advantages of the super-hard layer. The technology does not have the problem of the winding property, and the subsequent hardening treatment of the substrate is convenient, and the treatment can be repeated many times, so that the applicability of the technology is more extensive.

3. Technical advantages

Diffusion metal carbide coating technology is widely used in Japan, European countries, Australia, South Korea and other countries. According to the survey, many of the imported molds on the imported equipment use this technology. When these molds are made in China, due to the lack of corresponding mature technology, the mold life is often low, and some can not be localized.

This technology has been studied in the 1970s. However, due to various conditions, processes and equipment are often difficult to pass the test of batch and long-term production, making some practical problems in the technology difficult to expose or difficult to solve, often halfway. . In the process of research and application for more than ten years, we have carried out in-depth research on the existing problems in the process and equipment of the technology, and carried out effective improvement. The improved technology and complete sets of equipment have been able to meet the long-term requirements. The requirements of stable production, the life expectancy of the processed molds reached the life level of imported similar molds, and the production experience of various types of molds has been obtained, which laid a solid technical foundation for the large-scale application and application of this technology.

4. Scope of application

The diffusion metal carbide coating technology can be widely applied to various types of tooling or mechanical parts that are caused by wear and bite. Among them, failure due to wear (such as punching, cold heading, powder molding and other molds) can increase the life of several times to tens of times; the product or mold strain caused by the bite (such as extension die, flange Model, etc., can be fundamentally solved.

Applicable materials: mold steel, structural steel with carbon content greater than 0.3%, cast iron, hard alloy.

Second, stainless steel welded pipe mold surface super hardening treatment technology

The stainless steel welded pipe is formed on the welded pipe forming machine by rolling and forming a stainless steel plate through a plurality of molds. Due to the high strength of the stainless steel and the structure of the face-centered cubic lattice, it is easy to form work hardening, so that when the welded pipe is formed: on the one hand, the mold is subjected to a large friction force, so that the mold is easy to wear; on the other hand, the stainless steel sheet It is easy to form a bond (bite) with the surface of the mold, causing strain on the surface of the welded pipe and the mold. Therefore, a good stainless steel forming mold must have extremely high wear resistance and anti-bonding (biting) properties. Our analysis of imported welded pipe molds shows that the surface treatment of these types of molds is treated with super hard metal carbide or nitride coating.

Stainless steel welded pipe forming mold materials are generally made of high carbon and high chromium Cr12MoV (or SRD11, D2, DC53). At present, the following processes are commonly used in China to make molds: blanking → rough processing → heat treatment (high temperature quenching plus high temperature tempering) → finishing → nitriding → finished products (Note: In order to save costs, the general manufacturers now save the forging and Spheroidizing annealing is two time-consuming and costly processes). Since the Cr12MoV type material is a high carbon high chromium alloy steel, its original structure has a large composition segregation (this segregation cannot be eliminated even by general forging). In this way, the internal structure of the mold after heat treatment (high quenching and high recovery) is extremely uneven, and the macroscopic performance is extremely uneven in hardness (HRC is about forty to sixty degrees). After nitriding treatment, the unevenness of the mold surface cannot be eliminated. The hardness is even further reduced. In actual use, the surface of the mold and the welded pipe are easily pulled, and the life of the mold is low.

The mold surface super-hardening treatment technology researched by Hunan Tepu Electronics Co., Ltd. has been successfully applied to stainless steel welded pipe forming molds. The mold treated by the technology forms a metal carbide layer with a hardness of up to about HV3000 on the surface thereof. The carbide layer is dense and tightly combined with the substrate, does not affect the surface finish of the workpiece, and has extremely high wear resistance and seizure resistance. It fundamentally solves the problem of pulling the welded pipe, reduces the workload of the subsequent polishing process of the pipe and improves the product quality, greatly improves the service life of the die, and reduces the workload of after-sales service. Practice has shown that this technology has extremely high use value. The following is a comparison of the process mold and the nitriding mold.

1, performance:

Nitriding mold This process treatment mold Surface hardness: HV700~1000 or so HV3000 or so Base hardness: extremely uneven HRC58~62
HRC40~60

2. Process flow:

Nitriding mold: blanking → roughing → heat treatment (high quenching and high recovery) → finishing → nitriding → finished product

The process of processing the mold: cutting → all processing in place (no heat treatment required) → the process (base hardening and surface treatment once completed). → Grinding hole → finished product
It can be seen from the process flow that the processing cycle of the mold can be shortened by using the process.

3, the effect:

Compared with the nitriding mold, the mold processed by the process can fundamentally solve the pulling of the welded pipe, thereby reducing the workload of the subsequent polishing process of the welded pipe and improving the product quality (the pipe wall is reduced due to a large amount of polishing), and the service life of the die is greatly improved. Reduce after-sales service workload.

The mold surface super-hardening treatment technology developed by Hunan Tepu Electronics Co., Ltd. has been widely used in actual production and has been well received by customers. The process life of the mold is much larger than that of traditional processes such as nitriding. Improve, in some mold performance exceeds the foreign level, and the price is only 1/4~1/10 of the foreign equivalent.

The molds processed by this process include rolls, punches, color tube series cold work molds, standard parts molds, pyrophyllite molds, copper and aluminum extrusion molds, etc., which enable customers to have high benefits and make the molds cost-effective. Quality improvement