Aluminum alloy stamping is particularly prone to top damage and scratches during stamping production because the material is softer than metal iron, expensive, easy to break, and some aluminum alloy products require subsequent processing, such as wire drawing, anodizing, etc. In terms of manufacturing, special attention should be paid to the following points:
- For the case of not affecting the number of projects, the punching should be arranged in the back of the project, and even for products with a large number of punches, one more project can be considered and the punching should be arranged in the back.
- The aluminum material is softer and the mold is easier to block the material, so when designing the gap of the mold, it is advisable to put a gap of 10% of the thickness of the bilateral material.
- When bending and forming, because the aluminum material is easy to produce aluminum scraps during bending, it will cause spot damage and indentation. Better.
- For stamping parts that need to be processed after anode, if the flattening and flattening process is 180°, the product cannot be completely pressed, and complete pressing will cause acid spitting, and a 0.2-0.3MM seam should be left to ensure smooth acid. It flows out in time, so in this process, it is necessary to make a limit block and calibrate the mold to be higher than the mold.
- Because the aluminum material is brittle and easy to crack, especially in the case of reverse folding, try not to make a crimping line, even if you do, make the crimping line wider and shallower.
- All aluminum parts are required to be cut with slow-moving wire to prevent burrs and unsmooth blanking. Aluminum parts are prone to high temperature. Therefore, the hardness of the punch should be above 60°, at least SKD11 or above, and there should be no D2 difference. Mass punch.
The aluminum material is relatively soft, so it is very easy to produce top injuries, crush injuries, scratches, and deformations during stamping production. In addition to meeting the requirements on the mold, the following points must be done during stamping production:
- In order to stamp aluminum parts well and reduce the defect rate, we must first do 5S, especially cleaning, including molds, punching table, assembly line and packaging materials must be free of sharp debris, no dirt and regular clear rectification, The top and bottom of the mold must be cleaned and free of debris.
- If it is found that the product has a large burr, it must be sent to the mold for repair in time and follow up to the result.
- Aluminum parts are easy to heat up and become hard when they are stacked together. Therefore, when punching and blanking, it is necessary to apply some pressure oil on the material (which can dissipate heat and dredge the blanking material smoothly) before punching.
- Products with more punching holes need to be punched to clean the surface of the mold, so that the mold and the product will always be kept clean and free of debris, so as to reduce the top damage. If the top damage is found, the problem point of the top damage of the mold must be found and solved before continuing. Production.
- Flattening the mold push block will produce aluminum scraps, so the aluminum scraps under the push block must be cleaned every day after the push block is produced.
Characteristics and classification of body aluminum alloy
The aluminum alloy body is mainly composed of 5-series and 6-series aluminum alloys. Among them, the performance characteristics of the inner plate material require good formability, high plasticity and good connectivity, mainly the use of 5-series aluminum alloys and some 6-series aluminum alloys. For automobile outer panels, good plasticity is more conducive to forming. Therefore, 6-series aluminum alloys are widely used in outer coverings according to their heat-treatable strengthening properties.
The most widely used grades of aluminum alloy body at home and abroad are: AA6016, AA6022, AA6005, AA6009, etc. The 6 series are mostly used in the outer cover, and the 5 series such as AA5754 and AA5052 are mostly used in the inner plate. For example: Chrysler Hunter uses 6022 aluminum alloy as the outer cover material, Acura NSX uses 5052 aluminum alloy as the inner panel material, and 6 series aluminum alloy as the outer cover material. There are gaps, especially in punching performance.
Process planning features of body steel and aluminum stamping workshop
At present, most of the domestic mainstream OEMs use the steel-aluminum mixed line for production, and the process layout of the workshop is roughly the same as that of the traditional steel stamping workshop. According to the production characteristics of aluminum alloys and the production requirements of the workshop, its characteristics are mainly reflected in the following aspects. .
Difference from traditional stamping process
According to different material properties, aluminum alloy plates have their own characteristics in production line design, repair and grinding, mold use, and application of waste collection. Table 2 shows the comparison of stamping processes between steel plates and aluminum plates. In the process planning of the aluminum alloy stamping workshop, many different factors should be combined, and the production line should be flexibly set according to the actual steel-aluminum mixed line and the needs of planned production capacity to meet the switching of steel and aluminum in the production process, as shown in Figure 1. Steel and aluminum mixed line scrap line collection scheme.
The setting of aluminum plate rework and grinding room
When the aluminum plate is reworked and polished, a large amount of powder will be generated. When the powder concentration in the space is high, there will be a danger of explosion. It is generally believed that when the concentration reaches 30g/m3, the risk of explosion is greater, so the aluminum plate grinding room needs to be explosion-proof.
- ⑴According to the characteristics of the aluminum dust itself, the dust should be collected in a centralized manner for pressure relief and decompression treatment. In addition, the aluminum powder grinding room needs to be isolated from the production area.
- ⑵Aluminum plate grinding requires a closed grinding room and a complete dust removal system. The grinding room is closed to isolate the outside world from the grinding work area to isolate sparks and dust from the outside world, and the dust removal system is used to reduce the dust concentration in the grinding room.
- (3) The ventilation frequency in the grinding room is not less than 50 times/h, and the wind speed in the pipeline is not less than 20m/s. In order to ensure that the dust concentration in the grinding area will not reach the concentration limit and cause an explosion.
- ⑷ Generally, dust explosions occur in dust collectors. When an explosion occurs, a strong shock wave will be generated. The dust in the pipeline will be raised by the shock wave and diffused. The diffused dust will be transmitted back to the factory building, which will cause a secondary explosion in the factory building. Therefore, it is necessary to add an explosion-proof isolation valve to isolate the diffusion of dust in the pipeline, and isolate the grinding work area from the explosion area. When the dust collector explodes, it should be vented to the open area outside the workshop.
Storage and maintenance of aluminum plates
Based on the active characteristics of the aluminum plate material, when storing the aluminum plate, it is necessary to pay attention to the influence of the oxidation and damage of the aluminum plate on the subsequent production, and strengthen the maintenance of the aluminum plate before production to ensure the yield of the product during the production process.
- (1) After the failure and hardening of the aluminum plate material, the yield strength will increase and the plasticity will decrease, which will affect the subsequent forming and hemming. It is necessary to comprehensively consider the plasticity requirements of the material during mold manufacturing. Before production, it is necessary to check whether the state of the material meets the production requirements.
- (2) The aluminum plate material should be used immediately after unpacking. Before use, it should be cleaned and oiled online. The drawing oil should meet the requirements of aluminum plate forming.
- (3) Since the aluminum plate is easy to be oxidized, it needs to be tightly packaged and cannot be placed outside. The hardness of the aluminum plate is lower than that of the steel plate, so it is easy to be scratched and bruised, so special attention should be paid during handling; in addition, the outer plate parts cannot be stacked and stored, and need to be transported on a pallet, and the contact area between the bracket of the pallet and the aluminum plate should be small. , and ensure clean and soft requirements.
For the current situation that aluminum plate stamping applications are becoming more and more common, according to the characteristics of the aluminum plate itself, in the process planning of the stamping workshop, the steel-aluminum mixed line setting, the collection of steel and aluminum plate waste, the setting of the aluminum plate rework and grinding room, and the storage and maintenance of the aluminum plate should be integrated. Considering that it is used to improve the efficiency of aluminum plate production and improve the flexible layout of the stamping workshop, it is conducive to the reasonable and efficient operation of the stamping workshop equipment.