Before entering the punch, the metal plate needs to be blanking, that is, according to the final shape of the stamping part, the metal plate is cut into geometric shapes with equipment such as press, plate shear and fixed length shear, and then stamped and leveled. This blanking process can be done by the steel distribution center or by the stamping enterprise itself. Automobile main engine plants and large stamping plants generally use mechanical presses to blanking by themselves, but they need to invest in presses and various blanking molds with more land occupation. The idea of using laser equipment to replace the blanking of press was put forward by Americans as early as about 2000, but the dominant position at that time was carbon dioxide laser, which could not meet the large-scale cutting load, and the cutting efficiency could not meet the large-scale production demand of stamping.
Germany and Japan, powerful automobile manufacturers, also began to try this technology soon. One of the important reasons is that laser blanking of metal plates with high strength and high surface quality requirements has more advantages than press. In 2015, Daimler ordered two Schuler laser blanking lines for its Mercedes Benz plant in kupenheim. In order to ensure the blanking efficiency, the production line applies Schuler's dynamic flow technology, which can flatten and cut moving materials at high speed, and does not need pit and complex press foundation. The laser blanking production line adopts three parallel laser heads, which can cut blanking with a thickness of 0.8 to 3 cm and a width of 2150 cm. In October of the same year, Honda installed a modelless intelligent laser blanking system (ilbs) for mass production in Yorii factory in Japan, realizing mass production. It mainly developed three key technologies: high-speed laser cutting, high acceleration H-type Mahatma gantry system and continuous feeding conveying system. Mahatma laser uncoiling and blanking line is especially suitable for the production and application of multi variety and small batch products. It can be completed only by switching the program, so there is no need to change the mold frequently, and the related mold maintenance and mold storage costs are completely avoided. The production line equipped with laser blanking can process the widest range of sheet materials, such as aluminum or high-strength steel, and ensure a high level of product quality, and even process outer covering parts with high surface requirements. Laser cutting can also improve the utilization of materials and make the shape of cutting close to the final shape of parts as much as possible. Domestic Han's laser and other enterprises are also entering this field to replace the demand of some blanking presses.
Aluminum alloy sheet forming
Automobile lightweight is the direction of efforts of major automobile manufacturers, not only to reduce fuel consumption, but also to give consumers the feeling that once high-strength steel or even aluminum alloy is used
Some distinctive technologies and processes have appeared for many years, but they have not been widely used and are not widely known in the industry. It is hoped that this paper will provide an index for interested parts, equipment and main engine manufacturers and relevant researchers to further understand and enrich the process selection. The car's grade and sense of fashion have come up. For example, Tesla and Jaguar regard the all aluminum body as an important selling point to meet the identification needs of fashionable and avant-garde rich people. Under the same volume and capacity, the aluminum alloy vehicle reduces the weight of the vehicle and reduces the center of gravity. The strength of the aluminum hub is large. The spokes can be designed smaller, the cavity is larger, the moment of inertia is small, the braking heat dissipation is fast, and the acceleration is fast, which improves the sense of control and comfort. Aluminum has good energy absorption, which can absorb more kinetic energy during collision and reduce the damage to passengers. In addition, the utilization rate of aluminum is very high, and the damage is only about 5%. In addition to the body and wheel hub, the chassis, anti-collision beam, floor, power battery, motor drive / transmission assembly and seat are all optimized using aluminum forming, which is also the reason why aluminum alloy has become the hottest topic in the industry. The familiar Audi a8lhybird uses an all aluminum body frame structure (ASF) body with a curb weight of 2035kg, which is the lightest of its kind in large hybrid luxury cars. There is also Cadillac's CT6 model, which is produced in Shanghai's Jinqiao factory and is at the same level as Audi A6, Mercedes Benz e series and Volvo S90. It is said that 11 materials are used to manufacture the body, of which aluminum accounts for more than 57%. Cadillac's CT6 car factory is nearly 5.179 meters, the curb weight is between 1655 ~ 1975 kg, and the body in white weighs less than 380 kg, It is about 100kg lighter than similar models of similar sizes.
At present, the most famous in China's all aluminum body field is the Jaguar XLF produced by Changshu Chery Jaguar Land Rover. They cooperate with aluminum giant nobelis. It is said that the application ratio of body aluminum alloy exceeds 75%. The stamping adopts two servo stamping lines, the fastest beat is 20 pieces per minute, and the automation rate is as high as 90%. Among them, the first line of stamping is the production line of five Servo Presses provided by Huitian, Japan. The maximum tonnage of a single press is 2500 tons, which can be compatible with stamping steel and aluminum to meet the parallel production of different models.
Aluminum alloy has low ductility, high yield ratio, small R value, high stamping forming difficulty and high defective rate, which requires high die processing ability and detection ability. In addition, aluminum alloy has active chemical properties and dense oxide layer on the surface. Traditional spot welding and laser welding are difficult to achieve stable welding. Advanced connection methods such as aluminum laser brazing, aluminum resistance welding, self tapping screw connection and self punching riveting are widely used in aluminum and aluminum steel welding. MFC often receives inquiries from people in the industry and wants to know about the technical materials or forums of aluminum alloy forming and welding. After asking around, it finds that this is a very popular topic. Almost the pioneers in the field of forging and stamping are overcoming various problems, the blockade of technology is very strict, and the external communication of technicians is limited to the substantive dry goods. It is believed that as more people invest in the field of aluminum alloy, the cost will gradually drop. Just like high-strength steel, it can also be popularized in medium and low-grade cars, and gradually reduce the high maintenance cost of aluminum body.
Mark·Xu