ã€China Aluminum Industry Network】Aluminum extrusion porous mold is an effective method to improve production efficiency. It can influence the production of porous molds, including mold design, mold making, extrusion production and mold maintenance. This article briefly introduces the precautions of each link and Production experience. 1 mold design 1.1 Mold cavity shrinkage given: First, according to the principle of shrinking the single hole to give the overall shrink (different alloy shrinkage rate is different, such as 6063 material shrinkage rate of 1%), and then press the mold hole position to give a counter-mold pre-deformation deformation, as shown; 1.2 mold structure design 1.2.1 cavity placement Double-hole cavity general placement methods are: left and right discharge (symmetrical or same direction) and up and down discharge (symmetrical or same direction). Three-hole cavity general placement methods are: three-hole flat discharge material, character-shaped material, inverted character-shaped material. Other porous cavity placement is basically based on the two-hole and three-hole principle. Symmetrical discharge: Infeed and discharge are exactly the same, and the length of the mold design does not need to be considered. After the extrusion, the saw is convenient for surface treatment, and a plurality of different material frames are needed to store the material, which affects the work efficiency of the saw. Simultaneous discharge: The discharge direction of each hole is the same, no special differentiation is required after the saw. The operation of the sawing personnel is relatively simple, but the design flow rate requires high, and the discharge length of each hole is more difficult to control. 1.2.2 Split hole design The existing porous molds are more commonly used for both porous feeds and porous feeds. Pictured: Porous separate feeding structure (Fig. 3): When extruding, the entire rod is first divided into two identical dummy rods, and then enters the orifice. Advantages: The difference between the length of the discharge of each hole is small, and the mold has strong anti-ballistic ability. Disadvantages: low economicality. Relative to other structures, larger die sizes are required, and aluminum rods of the same specifications have smaller outer diameters. Porous monolithic feed structure (Figure 4): The aluminum flow directly enters the shunt holes during extrusion and reaches the feed balance for each hole through a separate weld chamber. Advantages: high economical, convenient for fabric hole design. Disadvantages: Each hole has a large difference in the length of the material to be discharged, which requires a higher processing precision. The mold has a weaker anti-ballistic ability. 1.2.3 Bridge Thickness Design The bridge thickness (Figure 6) is proportional to the bridge span (5). The bridge spans long, and the thicker the bridge is, the better the strength of the mold is to be ensured, the size of the mold will increase, and the extrusion force will increase. Therefore, it is only necessary to ensure adequate aluminum flow welding and the bridge spans as short as possible. 1.3 Work with given Personally think that the profile outflow depends mainly on the proportion of the split hole, the working belt is only used as an auxiliary forming, but the "U" shaped material opening, "T" shaped part color difference and large plane surface quality and working belt given a greater relationship . The working scale is generally 1.2-3.5 times the wall thickness. 1.4 Material Selection Compared with the single hole mold, the porous mold has large changes in the extrusion process, which provides a good foundation for the stability and service life of the mold, and it needs to use steel materials with better toughness. 2 Production processing 2.1 Processing Points Most of the use of CNC processing, in addition to slow line cutting cavity, cylindrical, EDM work under the mold with clean corners. The upper mold working belt needs to make high and low points; when machining the lower mold working belt, each hole needs to be discharged at the same time. The mold is equipped with a full stop with clearance fit, and the fit clearance is generally between 0.02mm and 0.06mm. 2.2 Heat Treatment Points The hardness is maintained between 48 and 50HRC, and the hardness of any position on the mold is within 2HRC. Pay attention to the position of the point where hardness is detected to avoid affecting the strength of the mold and the supporting support. 3 extrusion process 3.1 Extrusion process parameters Porous molds are prone to non-uniformity in the length of discharge, so as not to affect the judgment of mold repair, the extrusion process must be performed according to standards. The temperature difference at each position of the mold is within 5°C. By adjusting the extrusion speed and the aluminum rod temperature to achieve a consistent outlet temperature, 6063 material extrusion exit temperature control at 520 °C - 530 °C. The extrusion speed (advance speed of the master cylinder of the extruder) should be adjusted according to the stage. Before the order is completed, the two rods should be used to increase the speed. Record the situation after the speed increase to find a larger extrusion speed. The target profile extrusion speed is 30m/min. . Our extrusion parameters such as table 3.2 The use of the device In order to prevent the extrusion of the profiles extruded from the holes during the extrusion process, it is necessary to install a multi-component material device at the receiving table to create a separate movement zone for each extruded profile to avoid mutual contact and reduce Retired due to scratches. Figure 7 3.3 Cooling Wind Speed ​​Adjustment: When the profile emerges from the receiving table, it often causes knife bending phenomenon, which causes the hole profiles to overlap and then overlap. At the same time, the straightening and stretching rate will become large in order to cut off the knife bending phenomenon, resulting in scratches and straightening of the profile. Orange peel and size do not meet the requirements. To achieve simultaneous cooling, a gas tube or outlet can be used for nitrogen cooling at the receiving station. 4 mold repair The major problem of porous molds lies in the length of each hole and the uneven wall thickness. The mold must be checked carefully before the mold is repaired. The mold holes are in full compliance with the drawing requirements. The mold repair program is then done. The mold repair concept is to repair the mold slowly. , First repair the shape and length. 5 Concluding remarks Factors affecting the discharge of porous molds include design factors, mold processing, extrusion equipment accuracy, process and operation, among which mold processing, extrusion equipment accuracy, process and operation can be directly controlled to ensure compliance with standards. Only in this way can it be truly reflected. Mold design issues and subsequent stable production. According to several years of production tracking, the production efficiency of porous molds is improved by more than 50% compared with that of single-hole molds. Especially for single-order high-volume profiles, the porous extrusion efficiency far exceeds the single-hole extrusion efficiency, so the production efficiency of porous molds is relatively high. There is a greater advantage in promotion. Each company has its own flagship product, but there are also many products that do not have a single order quantity. For example, if the number of single orders is small, using too few double-hole die-squeezing bars will result in excessive production costs, and it may be possible to achieve a model in the future. Multi-type molds, especially existing insulation materials, two strips are generally received orders at the same time, if you can achieve a multi-model, you can reduce the production of many circulation links. Therefore, the development of porous molds still has a lot of room for development. There are also many room for technological upgrading. It is necessary to communicate with the industry and work together to promote the development of the aluminum industry. Source: Lw2016 Forum Collection Author: Xiao Wenhui, Yan Ting column
