Alloy parts processing operation skills
Aluminum alloy parts deform during processing. In addition to the reasons mentioned above, in actual operation, the operating method is also very important.
(1) For parts with large aluminum allowance, in order to have better heat dissipation conditions during processing and avoid heat concentration, symmetrical processing should be used during processing. If there is a 90mm thick sheet that needs to be processed to 60mm, if one side is milled and the other side is milled immediately, and the next size is processed once, the flatness will reach 5mm; if repeated feed symmetrical processing is used, each side is processed twice To the back size, the flatness can be guaranteed to reach 0.3mm.
(2) Reduce cutting force and cutting heat by changing the cutting amount. Among the three elements of cutting amount, the amount of back-cutting has a great influence on cutting force. If the machining allowance is too large, the cutting force of a pass is too large, which will not only deform the parts, but also affect the rigidity of the machine tool spindle and reduce the durability of the tool. If you reduce the amount of knives back, the production efficiency will be greatly reduced. However, high-speed milling is used in CNC machining, which can overcome this problem. While reducing the amount of back-grabbing, as long as the feed is increased correspondingly and the speed of the machine tool is increased, the cutting force can be reduced while ensuring the processing efficiency.
(3) If there are multiple cavities on the plate part, it is not advisable to use a cavity-by-cavity sequential processing method during processing, as this will easily cause uneven stress and deformation of the parts. Multi-layer processing is adopted, and each layer is processed to all cavities at the same time as much as possible, and then the next layer is processed to make the parts evenly stressed and reduce deformation.
(4) Thin-walled workpieces are deformed due to clamping during processing, and even finishing is unavoidable. In order to reduce the deformation of the workpiece to a very low limit, the pressing piece can be loosened before the finishing process reaches the following size, so that the workpiece can be restored to its original state freely, and then slightly compressed, subject to the rigid clamping of the workpiece. (It depends entirely on the hand feeling), so that the ideal processing effect can be obtained. In short, the point of action of the clamping force is on the supporting surface, and the clamping force should act in the direction of good rigidity of the workpiece. Under the premise of ensuring that the workpiece does not loosen, the smaller the clamping force, the better.
(5) The order of the knife should also be paid attention to. Rough machining emphasizes the improvement of machining efficiency and the pursuit of removal rate per unit time. Generally, up-cut milling can be used. That is, the excess material on the surface of the blank is removed at a faster speed and in a shorter time, and the geometric contour required for finishing is basically formed. The emphasis of finishing is high precision and high quality, and down milling should be used. Because the cutting thickness of the cutter teeth gradually decreases from larger to zero during down milling, the degree of work hardening is greatly reduced, and at the same time the degree of deformation of the parts is reduced.
(6) When machining parts with cavities, try not to let the milling cutter plunge directly into the part like a drill bit, resulting in insufficient chip capacity of the milling cutter, unsmooth chip removal, and overheating, expansion, and Unfavorable phenomena such as knife collapse and broken knife. First, drill the hole with a drill of the same size as the milling cutter or one size larger, and then mill it with the milling cutter. Alternatively, the CAM software can be used to produce the spiral cutting program.