CAR Lamp molds that require mass production often need to choose annealed electroslag remelting grade hot work steel, of which the heat treatment quality is the key link to determine whether the mold can be successfully mass-produced. Taking a large and complex headlight die as an example, the things worth noting are as follows:
Car Lamp Molds
Car lamp molds must retain a larger R angle before heat treatment
A larger R angle can prevent the risk of cracking at right angles where the core material stress is concentrated during rapid cooling at high temperature during quenching. Generally, the transition positions that require an appropriate R angle include: notched grooves, concave The corners of the bottom of the frame, the steps, the root of the boss, etc. The picture on the right is an example of cracking during quenching caused by too small R angle of the mold.
Rough machining stress relief treatment
The processing volume of the car lamp mold is large, the size drop is very different, and a large processing stress is accumulated during the rough processing. It is recommended to heat it to 650 ℃ after rough processing, and cool it slowly to 500 ℃ after heat preservation, and then cool it in the air to release the stress. Reduce the amount of deformation during subsequent hardening.
Quenching and tempering for car lamp molds
The structure of the lamp mold is complex and the water channels are dense. Before quenching, protective measures must be applied to the cooling water channels. It is recommended to use a graded cooling process during the hardening process to avoid cracking of the cooling water channels during the heat treatment process to the greatest extent, resulting in water leakage during the mold test process. The occurrence of catastrophic accidents. At the same time, three tempering treatments are recommended to fully eliminate thermal stress and microstructure transformation stress.
Heat treatment after EDM
The electric discharge machining of the car lamp mold is large. After heat treatment, it is recommended to discharge with high frequency and low current. After the discharge is completed, stress relief tempering at 25-30 °C lower than the original tempering temperature and thorough grinding to remove the metamorphic layer.
Hardness range
The structure of the car lamp mold (water path) is complex, and the reasonable working hardness range is HRC44-52, can improve the wear resistance of the mold surface through surface treatment such as laser quenching or PVD coating. One-sided pursuit of high hardness such as (HRC52-54) will reduce the mold toughness and crack resistance, and increase the early cracking during the injection molding process. risk.
The so-called vacuum heat treatment is a heat treatment method in which the workpiece is heated to the required temperature in a 10-1~10-2Pa vacuum medium, and then cooled in different media at different cooling rates.
Vacuum heat treatment is called high-efficiency, energy-saving and pollution-free clean heat treatment by the contemporary heat treatment industry. Vacuum heat-treated parts have a series of advantages such as no oxidation, no decarburization, degassing, degreasing, good surface quality, small deformation, high comprehensive mechanical properties, good reliability (good repeatability, stable life), etc. Therefore, vacuum heat treatment is widely valued and widely used at home and abroad. And the popularity of vacuum heat treatment is taken as an important symbol to measure the level of a country’s heat treatment technology. Vacuum heat treatment technology has been a hot spot in the development of heat treatment technology in the past forty years, and it is also an important field of advanced manufacturing technology today.
Since the founding of the People’s Republic of China, my country has made great progress in mold materials, and initially established a mold material system with Chinese characteristics, including cold work die steel, hot work die steel, plastic mold steel and other series of materials, and in the mold manufacturing industry widely used. At the same time, according to different working conditions and environmental factors, a variety of advanced mold materials have been developed.
