In general, if there is no unscheduled downtime for aluminum extrusion, the maximum production is mainly determined by the extrusion speed, which is subject to four factors, three of which are fixed and the other is variable. The first factor is the extrusion pressure of the extruder, which can be smoothly extruded when the ingot temperature is low; the second factor is the mold design, in which the friction between the metal and the die wall can generally raise the temperature of the aluminum alloy passing through 35-62 ℃; the third factor is the characteristics of the extruded alloy, which is an uncontrollable factor limiting the extrusion speed, and the outlet temperature of the profile is generally not It can exceed 540 ℃, otherwise, the surface quality of the material will be reduced, the die marks will be significantly increased, and even aluminum sticking, dents, microcracks, tears, etc. will appear. The last factor is temperature and its degree of control.

Because of the variety and specification of aluminum profile, the complex material flow and the bad load condition of the extrusion die, the development of aluminum profile extrusion products and the design of the die become an arduous task. The traditional production mode which relies on experience design and trial mold repair can not meet the needs of modern economic development. In the market economy environment where efficiency is life and quality is the key, aluminum extrusion enterprises attach great importance to improving the success rate of mold design and processing, as well as the output 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 enterprises.

In this case, how to improve the productivity of extruder has become an urgent matter. There are many measures to improve the productivity, such as improving the installation level, improving the quality of workers, and improving the management level.

I. main factors affecting product output and quality

1. Importance of aluminum bar quality

For aluminum profiles with high quality requirements, the quality of aluminum bars directly affects the quality and output of products. High quality ingots with alloying, crystallizing, refining and homogenization can reduce the die loss, improve the effective production time, and thus improve the extrusion speed to achieve the maximum output.

2. Advanced equipment and high-quality workers are the premise of increasing production

For improving the output of extrusion products, advanced equipment, high-quality workers and modern scientific management play an important role.

3. Importance of mould

Reasonable mold design, timely nitriding to improve the hardness and finish of mold working belt, reduce the number of mold changes, reduce non work efficiency time, improve product quality and reduce scrap rate are very important to achieve the maximum output.

4. Important relationship between temperature control and output improvement

Generally, if there is no unscheduled downtime, the maximum production is mainly determined by the extrusion speed, which is subject to four factors, three of which are fixed. The last factor is that temperature and its degree of control are variable. If the extruding pressure of the extruder is not large enough, it is difficult to extrude smoothly or even plug the die and it can not move, the ingot temperature can be increased, but the extruding speed should be lower to prevent the outlet temperature of the material from being too high. Each alloy has its specific optimum extrusion (ingot) temperature. The production practice shows that the ingot temperature is best kept at about 430 ℃ (when the extrusion speed is ≥ 16mm / s). The die temperature of 6063 alloy profile shall not exceed 500 ℃, and that of 6061 alloy profile shall not exceed 525 ℃. The output and quality of the product will also be affected by the small change of the mold temperature

The temperature of extrusion barrel is also very important, especially the temperature rise in preheating stage should be paid attention to, and excessive thermal stress between layers should be avoided, and it is better to raise the temperature of extrusion barrel and bushing to the working temperature at the same time. The preheating and heating speed shall not be greater than 38 ℃ / h. The best preheating specification is: raise to 235 ℃, keep warm for 8h, keep warm to 430 ℃, keep warm for 4h, and then put into operation. In this way, not only the internal and external temperature can be ensured to be uniform, but also enough time is available to eliminate all internal thermal stresses. Of course, heating the extrusion tube in the furnace is the best preheating method

In the process of extrusion, the temperature of extrusion barrel should be 15-40 ℃ lower than that of ingot. If the extrusion speed is too fast, so that the temperature of the extrusion barrel rises to higher than the temperature of the ingot, it is necessary to try to reduce the temperature of the extrusion barrel, which is not only a troublesome work, but also the output will decline. In the process of production speed rising, sometimes the heating element controlled by the electric couple will be cut off, but the temperature of the extrusion barrel is still rising. If the temperature of extrusion barrel is higher than 470 ℃, the waste products will rise. The ideal extrusion temperature should be determined according to different alloys

In the production of high-grade and high-quality surface profiles, the temperature of the extrusion pad should also be strictly controlled to reduce the amount of waste products with inconsistent surface tone. The quality of the fixed extrusion pad is much better than that of the active one, and it can accumulate more heat, so it can reduce the temperature of the billet end, reduce the impurities entering the profile, and help to increase the output

Mold temperature plays an important role in obtaining high output, generally not lower than 430 ℃; on the other hand, it should not be too high, otherwise, not only hardness may decrease, but also oxidation will occur, mainly in the working zone. In the heating process of the mould, it should be avoided that the mould is close to each other and obstructs the air circulation. It is better to use the box type heating furnace with grid, each mold is placed in a separate box

In the process of extrusion, the temperature of ingot can rise up to about 40 ℃ or higher, which is mainly determined by the design of die. In order to obtain the maximum output, each temperature should not be ignored. Each temperature should be recorded and strictly controlled to find out the relationship between the maximum output of the machine and each temperature

Finally, the staff of extrusion plant should keep in mind that the precise control of temperature is very important to improve the output.

II. Main ways to improve product output and quality

Because the output and quality of products mainly depend on raw materials, equipment and molds, appropriate process parameter setting and workers' quality. The specific ways to improve the output and quality of products and reduce the quantity of waste products are as follows:

- select high-quality ingots that are alloyed, crystallized, refined and homogenized.

- optimize the mold design, timely nitriding to improve the hardness and finish of the working belt of the mold, reduce the number of mold changes, and reduce non work efficiency time.

- lengthen the ingot and reduce the amount of press surplus

- increase the solid yield of metal by using hot shear

- saw off the welding joint of the profile, and select the appropriate ingot length and extrusion length - reduce the ingot temperature and increase the extrusion speed to ensure the outlet temperature.