Parts of the aluminum material are deformed during processing. In addition to the above reasons, the operation method is also very important in actual operation.
1. For parts with large machining allowance, in order to make them have better heat dissipation conditions during processing, avoid heat concentration, and symmetrical processing should be used during processing. If a piece of 90mm thick sheet needs to be machined to 60mm, if the other side is milled, the other side will be milled, and the flatness will be 5mm. Once the symmetrical processing is repeated, each side is processed twice. The final size guarantees a flatness of 0.3mm.
2. If there are multiple cavities on the plate parts, it is not advisable to use a cavity and a cavity ordering method during processing, which is easy to cause uneven deformation of the parts. Multi-layer processing is used, each layer is processed into all the cavities at the same time, and then the next layer is processed to make the parts evenly stressed and reduce deformation.
3. Reduce the cutting force and cutting heat by changing the amount of cutting. Among the three factors of cutting amount, the amount of backing knife has a great influence on the cutting force. If the machining allowance is too large, the cutting force of one pass will be too large, which will not only deform the parts, but also affect the rigidity of the machine spindle and reduce the durability of the tool. If you reduce the amount of back-to-back knives, the production efficiency will be greatly reduced. However, high-speed milling in CNC machining can overcome this problem. While reducing the amount of back-feeding, as long as the feed is increased correspondingly and the speed of the machine tool is increased, the cutting force can be reduced and the machining efficiency can be ensured.
4, the order of the knife must also pay attention to. Roughing emphasizes the improvement of processing efficiency and the pursuit of resection rate per unit time. Generally, up-cut milling can be used. That is, the excess material on the surface of the blank is cut at the fastest speed and in the shortest time, and the geometric contour required for finishing is basically formed. The finishing work emphasizes high precision and high quality, and it is recommended to use down milling. Because the cutting thickness of the cutters gradually decreases from the maximum to zero during the milling, the degree of work hardening is greatly reduced, and the degree of deformation of the parts is alleviated. 5. Thin-walled workpieces are deformed due to clamping during processing, even if finishing is difficult to avoid. In order to minimize the deformation of the workpiece, the pressing piece can be loosened before the finishing is reached to the final size, so that the workpiece can be freely restored to its original shape, and then slightly pressed, so that the workpiece can be clamped. According to the hand feeling, this can achieve the desired processing effect. In short, the point of application of the clamping force is preferably on the bearing surface, and the clamping force should be applied to the direction of the rigidity of the workpiece. Under the premise of ensuring that the workpiece is not loose, the clamping force is as small as possible.
6. When processingthe cavity parts, try not to let the milling cutter directly into the parts like a drill bit when machining the cavity, which leads to insufficient space of the milling cutter and the chip removal is not smooth, resulting in overheating, expansion and collapse of the parts. Unfavorable phenomena such as knives and broken knives. First drill the hole with a drill of the same size or larger size as the milling cutter, and then mill with a milling cutter. Alternatively, the CAM software can be used to produce a spiral undercut program.
