In recent years, along with the rapid development of social economy, people’s awareness of environmental protection has been continuously strengthened. The state has introduced the mandatory laws and regulations on automobiles, and safety, environmental protection and energy conservation have gradually developed into three essential elements for automobile production. The light weight of automobiles is a major trend in the development of automobiles today. Lightweight can effectively improve the economics of fuel use and achieve the goal of energy saving and emission reduction. The relevant data shows that if a car can reduce its own weight by 10%, its fuel efficiency will increase by 7 to 8%, and the vehicle’s curb weight will be reduced by 100kg, so its fuel consumption will also drop. Therefore, the realization of lightweight vehicles will help the car to save energy and protect the environment. The hot stamping forming technology is a main means to realize the lightweight of the automobile, which can reduce the thickness of the material and ensure the goal of weight reduction on the basis of ensuring the strength of the stamping part.

1. The basic principle of hot stamping forming technology

The so-called hot stamping forming technology refers to the use of high-temperature conditions, the yield strength of the metal will be rapidly reduced, and its ductility and plasticity will be rapidly enhanced, so that the metal becomes a part with the help of the mold. a process technology.

The basic principle is: heating a special boron alloy steel (with high strength) to make it completely austenitized, then placing the red hot sheet in a mold (cooling system) for stamping and cooling Quenching, in turn, transforms the steel sheet structure from austenite to martensite, and finally obtains a steel with an ultra-high strength ratio. This technology has been widely used in industrial production in some developed countries due to its advantages of improving safety and reducing quality, especially for the production of high-strength steel.

2. Advantages of hot stamping technology

In contrast to cold forming technology, hot stamping technology has many advantages, as shown in the following points.

First, the strength of the parts after hot stamping has been greatly improved by rapid cooling and quenching. If such a part is used in a car, the number and thickness of the parts can be controlled on the basis of ensuring the safety performance of the body collision, and the goal of reducing the weight of the vehicle body can be achieved.

Second, there is better formability. Under high temperature conditions, the material has better plasticity and relatively high elongation, which can form extremely complicated parts, which is impossible to achieve by cold stamping; in addition, some parts are subjected to cold forming technology. Processing requires several processes and molds, but thermoforming can be formed in one operation.

Third, reduce the tonnage of the decompression machine. At the time of thermoforming, the flow stress of the material is greatly affected by temperature. When the temperature is above 800 °C, the flow stress of the material will decrease, about 200 MPa. Therefore, under high temperature conditions, rapid forming can reduce the forming force, reduce the tonnage of the reducer, and ultimately reduce the investment cost of the equipment. .

Fourth, there is a relatively high dimensional accuracy. When parts are manufactured by cold forming technology, the rebound often causes defects in the parts, especially after the high-strength steel parts are formed, and there is a great rebound. However, when parts are produced by thermoforming technology, there is no rebound, and thus a product with relatively high geometric accuracy can be obtained.

Fifth, the parts made by thermoforming technology have better surface stiffness, hardness and anti-concavity. Nevertheless, hot stamping forming technology also has some shortcomings, that is, the production cycle is relatively slow, the energy consumption of the hot stamping die is relatively large, the cost of investing in the hot stamping production line is large, and the like.