Optimization and improvement of extrusion quality and output of aluminum profiles
Due to the variety of specifications of aluminum profiles and the complicated material flow conditions during the extrusion process, the extrusion die is subjected to poor load conditions, making the development of aluminum extrusion products and the design of molds an arduous task. Traditional production models that rely on empirical design and rework of test models are no longer sufficient for the needs of modern economic development. In the market economy environment where efficiency is life and quality is the key, aluminum extrusion enterprises pay more attention to improving the success rate of mold design and processing and the yield and yield of extrusion. In the production of aluminum and aluminum alloy semi-finished products, extrusion is one of the main forming processes. The quality of extrusion die and the speed of extrusion directly affect the product quality and output of aluminum and aluminum alloy extrusion production enterprises.
In this case, how to increase the productivity of the extruder has become a top priority. There are many measures to improve productivity, and improving the level of installed capacity, improving the quality of workers, and improving management levels are all effective measures.
First, the main factors affecting the output and quality of products
1, the importance of the quality of aluminum rods
For aluminum profiles with high quality requirements, the quality of aluminum rods directly affects the quality and output of the products. Alloying, graining, refining and homogenization of high quality ingots can reduce the loss of the mold and improve the effective Production time, thereby increasing the extrusion speed to achieve maximum output.
2. Advanced equipment and high-quality workers are prerequisites for increasing production.
Advanced equipment, high-quality workers, and modern scientific management play a vital role in improving the output of extruded products.
3, the importance of the mold
Reasonable mold design, timely nitriding to improve the hardness and smoothness of the mold work belt, reduce the number of mold changes, reduce non-work efficiency time, improve product quality and reduce scrap rate, is very important to achieve maximum output.
4. The important relationship between temperature control and increasing production
Typically, if there are no unscheduled downtimes, then the maximum output is primarily determined by the extrusion speed, while the latter is subject to four factors, three of which are fixed. The last factor is that the temperature and its degree of control are variable.
The first factor is the extrusion force of the extruder. The large pressing force can be squeezed smoothly when the billet temperature is low. The second factor is the mold design. The friction between the metal and the mold wall during extrusion is usually The temperature of the passed aluminum alloy is raised by 35-62 ° C; the third factor is the characteristic of the extruded alloy, which is an uncontrollable factor limiting the extrusion speed. The outlet temperature of the profile generally cannot exceed 540 ° C. Otherwise, the surface of the material The quality will drop, the mold marks will be significantly aggravated, and even aluminum, gravure, micro-cracks, tears, etc. will appear. The last factor is the temperature and how much it is controlled.
If the extrusion force of the extruder is not large enough, it is difficult to squeeze smoothly or even when the plugging phenomenon occurs, the billet temperature can be increased, but the extrusion speed should be lower to prevent the material from exiting the temperature. high. Each alloy has its own specific optimum extrusion temperature.
Production practice has proved that the temperature of the ingot is preferably maintained at about 430 ° C (extrusion speed ≥ 16 mm / s). The mold release temperature of 6063 alloy profile shall not exceed 500 °C, and the mold release temperature of 6061 alloy profile shall not exceed 525 °C. Small changes in the temperature of the mold will also affect the yield and quality of the product.
The temperature of the extrusion cylinder is also very important. In particular, the temperature rise during the preheating phase should be noted. Excessive thermal stresses between the layers should be avoided. It is preferable to raise the extrusion cylinder and the liner to the working temperature at the same time. The preheating heating rate must not exceed 38 °C / h. The best preheating specification is: raise it to 235 ° C, keep it warm for 8 h, continue to heat up to 430 ° C, and keep it working after 4 h of heat preservation. This not only ensures uniform temperature inside and outside, but also has enough time to eliminate all internal thermal stresses. Of course, heating the extrusion cylinder in the furnace is the best way to preheat.
During the extrusion process, the temperature of the extrusion barrel should be 15 to 40 ° C lower than the temperature of the ingot. If the extrusion speed is too fast, so that the temperature of the extrusion cylinder rises above the temperature of the ingot, it is necessary to try to lower the temperature of the extrusion cylinder, which is not only a troublesome work, but also the yield is lowered. During the increase in production speed, sometimes the heating element controlled by the galvanic couple is cut off, but the temperature of the extrusion tube is still rising. If the temperature of the extrusion tube is higher than 470 ° C, the extruded waste will rise. The ideal barrel temperature should be determined for the different alloys.
When producing high-quality surface profiles, the temperature of the extrusion pad should also be strictly controlled to reduce the amount of waste inconsistent surface tones. The quality of the fixed extrusion pad is much better than the activity, and it can accumulate more heat, which can reduce the temperature of the end of the ingot and reduce the entry of impurities into the profile, which helps to increase the yield.
The mold temperature plays an important role in obtaining high yield, generally not lower than 430 ° C; on the other hand, it should not be too high, otherwise, not only the hardness may decrease, but also oxidation, mainly in the working belt. During the heating of the mold, the molds should be avoided and the air circulation should be hindered. It is best to use a gridded box furnace, each in a separate box.
The temperature of the ingot during the extrusion process can be increased to about 40 ° C or higher, and the amount of increase is mainly determined by the mold design. In order to obtain maximum output, the temperature must not be neglected. Each temperature should be recorded and strictly controlled to find out the relationship between the maximum output of the machine and the temperature.
Finally, employees at extrusion plants should keep in mind that precise temperature control is critical to increasing production.
Second, the main way to improve product output and quality
As the output and quality of the products are mainly determined by raw materials, equipment and molds, appropriate process parameters, and the quality of workers. The specific ways to increase product yield and quality and reduce the amount of waste are as follows:
Select high quality ingots for alloying, graining, refining and homogenization;
Optimize the mold design, improve the hardness and smoothness of the mold working belt in time, reduce the number of mold changes, and reduce the non-work efficiency time;
Lengthen the ingot to reduce the amount of pressure;
Using hot shear to increase the metal yield;
Saw at the weld joint of the profile, select the appropriate length of the ingot and the length of the extrusion;
Reduce the temperature of the ingot and increase the extrusion speed to ensure the outlet temperature.
