Did you know that the diaphragm die uses a new process of heat treatment using high-frequency induction heating power?

The diaphragm die is the key mold for processing and producing diaphragms. The workpiece material was originally made of T10A steel. The diaphragm is a precision part of optical instruments. It is punched from 0.06-0.08mm thick low-alloy cold-rolled steel strip. It has high dimensional accuracy, so it requires high mold accuracy and performance. The hardness of the cold punching die of the diaphragm should be 61-64HRC. During production, it was found that when TlOA steel was used to make a cold punching die, the deformation of the die was too large after quenching, and the angle tolerance of the two punch pinholes was seriously out of tolerance, failing to meet the technical requirements. Later, Cr12Mo steel was used to produce diaphragm dies, but the cutting of Cr12Mo steel dies was difficult and the workpiece processability was not good. Therefore, the experiment used Crwmn steel to make the diaphragm die, and improved and optimized the heat treatment process, and achieved good results.

The process flow of CrWMn steel diaphragm die processing is: blank - spheroidizing annealing - rough machining - quenching and tempering - semi-finishing - stress relief and tempering - finishing - quenching - fine grinding - finished product. Its heat treatment process is as follows:

(1) Use high-frequency induction heating power for spheroidizing annealing heat treatment. The spheroidizing annealing process is 800℃ Baked below 500℃. 

(2) The quenching and tempering process is quenching oil at 830℃x15min, and then tempering at (700-720)℃X(1-2)h. The hardness of the mold after quenching and tempering is 22-26HRC.

(3) The stress relief annealing process is 640℃x4h. The purpose is to eliminate the stress caused by mold machining. The workpiece is released below 300℃.

(4) Quenching and tempering process. After quenching using a high-frequency induction heating power supply, the mold hardness is 61-64HRC, which meets the technical requirements and is of good quality.

After the CrWMn steel diaphragm cold stamping die adopts an improved heat treatment process, the die performance is excellent, the workpiece hardness is high and uniform, and the deformation is small. The main reasons and process characteristics are as follows:

(1) After quenching and tempering, the structure of the workpiece is sorbite, and the specific volume of sorbite is close to that of martensite. The deformation of the mold after quenching is small, and the processing performance is good, which facilitates the cutting of the workpiece.

(2) The stress relief annealing process is beneficial to reducing the quenching deformation of the workpiece.

(3) After quenching, the martensite grains of the mold are finer, and the carbides are dispersed and distributed, which improves the strength and hardness of the workpiece and enhances the wear resistance of the mold. There are two points that should be paid special attention to in the heat treatment of CrWMn steel diaphragm die. One is that the mold should be tempered immediately after quenching. Staying after quenching can easily cause mold quenching cracks. The other is that after tempering, it is cooled to room temperature and then cleaned. This is too early. Cleaning can easily cause cracks in the mold, causing the mold to fail and be scrapped.

As an important mold for processing and producing diaphragms, the diaphragm die directly affects the quality of the diaphragm. This article briefly introduces the heat treatment process of the diaphragm die. After using this process, the barrier die has excellent quality, high hardness, minimal deformation, and fully meets the technical requirements. If you don’t believe it, you can try it, I believe you will gain a lot.