Operational skills to reduce machining deformation
In addition to the above reasons, the parts of aluminum materials are deformed during the machining process. In addition to the above reasons, the operation method is also very important in practice.
1. For parts with large processing margins, in order to have better heat dissipation conditions during the machining process and avoid heat concentration, symmetric machining should be adopted. If a piece of 90mm thick sheet needs to be processed to 60mm, if one side is milled immediately milled, and the other side is processed to the final size at one time, the flatness will reach 5mm; if repeated knife symmetrical machining is used, each side is processed twice to the final size, which can ensure that the flatness reaches 0.3mm.
2. If there are multiple cavities on the plate part, it is not appropriate to use the sequential processing method of one cavity and one cavity during machining, which is easy to cause the uneven force of the part and deformation. Multiple layers are used to process. Each layer is processed to all cavities at the same time, and then the next layer is processed to make the parts evenly subjected to force and reduce deformation.
3. Reduce the cutting force and cutting heat by changing the cutting amount. Among the three elements of cutting dosage, the amount of back knife has a great impact on the cutting force. If the machining margin is too large, the cutting force of the first knife is too large, which will not only deform the parts, but also affect the rigidity of the spindle of the machine tool and reduce the durability of the tool. If the amount of back knives is reduced, the production efficiency will be greatly reduced. However, high-speed milling in CNC machining can overcome this problem. While reducing the amount of back-eat knives, as long as the feed is increased accordingly and the rotation speed of the machine tool is improved, the cutting force can be reduced and the machining efficiency can be guaranteed.
4. Pay attention to the order of knife walking. Rough machining emphasizes improving machining efficiency and pursuing the removal rate per unit time. Generally, reverse milling can be used. That is, the excess material on the rough surface is removed at the fastest speed and in the shortest time, and the geometric outline required for finishing is basically formed. The finishing emphasizes high precision and high quality, and it is advisable to use smooth milling. Because the cutting thickness of the cutting teeth gradually decreases from the maximum to zero during smooth milling, the hardening degree of machining is greatly reduced, and the deformation degree of the parts is reduced.
5. The deformation of thin-walled workpieces due to clamping during machining, even finishing is inevitable. In order to minimize the deformation of the workpiece, the compression part can be loosened before the finishing is about to reach the final size, so that the workpiece can be freely restored to its original state, and then slightly tightened, subject to the rigid gripping of the workpiece (completely on the feel), so that the ideal machining effect can be obtained. In short, the action point of the clamping force is best on the support surface. The clamping force should act in the direction of good rigidity of the workpiece. Under the premise of ensuring that the workpiece is not loose, the smaller the clamping force, the better.
6. When machining parts with cavity, try not to plunge the milling cutter directly into the part like a drill bit, resulting in insufficient chip space and unsmooth chip removal of the milling cutter, resulting in overheating, expansion of parts, and unfavorable phenomena such as collapse knives and broken cutters. First drill the hole with a drill bit the same size or size as the milling cutter, and then use a milling cutter. Alternatively, CAM software can be used to produce spiral cutting programs.
The main factor affecting the machining accuracy and surface quality of aluminum parts is that such parts are prone to deformation in the machining process, which requires operators to have certain operation experience and skills.
