CNC Knowledge: Processing measures and operation in operation to reduce the deformation of treatment of aluminum parts!

There are many reasons for the treatment and deformation of aluminum parts, which are linked to the material, the shape of the part, the production conditions, etc. There are mainly the following aspects: deformation caused by the internal stress of the white, deformation caused by the cutting force, the cutting heat and the deformation caused by the tightening force.
1. Process measures to reduce the deformation of treatment
1. Reduce the internal stress of white
Natural or artificial aging and the treatment of vibrations can partially eliminate the internal constraint of white. Pretramentation is also an effective process. For fat heads and large ears, due to the big margin, deformation is also important after treatment. If the excess of part of the white is pre -treated and the margin of each party is reduced, it can not only reduce the deformation of treatment of the subsequent process, but also release internal stress after pre -treatment for a period of time.
2. Improve tool cutting capacity
The material and geometric parameters of the tool have a significant impact on the cutting force and the cutting heat.
1) Reasonably select the geometric parameters of the tool.
① Input angle: By maintaining the resistance of the blade, choose a greater angle in front. Cutting force and cutting temperature. Avoid using negative front angle tools.
Back angle: The size of the rear angle has a direct impact on the wear of the surface of the rear blade and the quality of the transformed surface. Cutting thickness is an important condition for choosing the back angle. During rough grinding, due to the large power capacity, the heavy cutting load and the large heat production, the heat dissipation conditions of the tool are necessary, so the rear angle must be more little. During fine grinding, the edge is necessary to reduce the friction between the back surface of the back and the treatment surface and reduce elastic deformation.
③ Heliciodal angle: in order to make the milling smooth and reduce the grinding force, the helical angle must be selected as large as possible.
④ Main deviation angle: appropriately reduction of the main deviation angle can improve heat dissipation conditions and reduce the average temperature of the treatment area.
2) Improve the structure of tools.
① Reduce the number of shot teeth and increase the space of the chip. Since aluminum parts have high plasticity and large cutting deformation during treatment, it requires a large chip space, so it is preferable to have a large background of flea groove and a small number of Strawberry teeth.
② fine sharpen the teeth of the knife. The roughness value of the teeth cutting the tool of the tool must be less than RA = 0.4um. Before using a new knife, you should use the stone of thin oil to gently polish the cutter teeth at the front and behind the cutting teeth to eliminate the remaining terrifying and the slight brands serrated during the sharpening of cutting teeth. In this way, not only can the cutting heat be reduced, but the cutting deformation is also relatively low.
③ strictly control tools for tools. Once the tool, the surface roar value of the part is increased, the cutting temperature increases and the room deformation increases. Therefore, with the exception of the choice of tool materials with good wear resistance, the standard of wear of tools should not be greater than 0.2 mm, otherwise it is easy to cause an accumulation of ‘strangulation. During the cut, the temperature of the room must generally not exceed 100 ℃ to prevent deformation.
3. Improve the partner tightening method
For aluminum parts with thin walls with poor rigidity, the following tightening method can be used to reduce deformation:
① For thin walls with thin walls, if you use a three sludge egocentric chuck or a spring covered to tighten radially, once loosened after treatment, the work room will inevitably deform. Currently, a method of tightening the axial end surface with better rigidity should be used. Position the inner hole of the room, make a threaded mandrel, put it in the inner hole of the room and use a blanket plate to press the end side, then tighten it with a back. When machining the external circle, the tightening deformation can be avoided, thus obtaining a satisfactory machining precision.
② When processing parts with thin plates with thin walls, it is preferable to use an empty vacuum cup to obtain a tightening force uniformly distributed, then treat with a smaller quantity of cut, which can prevent the piece of well deform well.
In addition, the filling method can also be used. To increase the rigidity of the process of parts with thin walls, the part can be filled average to reduce the deformation of the part during tightening and cutting. For example, a cast iron containing 3% to 6% potassium nitrate is paid into the room.
4. Organize the process reasonably
During the high -speed cut, due to the large machining allocation and intermittent cutting, the milling process often produces vibrations, affecting the precision of machining and surface roughness. Consequently, the CNC high -speed cutting process can generally be divided into: rough treatment – semi -finish treatment – angle cleaning treatment – finish and other processes. For parts with high precision requirements, a secondary semi-finition is sometimes necessary, then the finish is made. After a rough treatment, the parts can be cooled naturally, eliminating the internal stress caused by rough treatment and a reduction in deformation. The left margin after rough treatment should be greater than the quantity of deformation, generally 1 to 2 mm. During the finish, the finishing surface of the parts must maintain a uniform processing allowance, generally 0.2 to 0.5 mm, so that the tool is in a stable state during the processing process, which can reduce considerably Cutting deformation, obtain good quality of surface treatment and ensure the precision of the products.
2. Operational skills to reduce treatment of treatment
In addition to the above reasons, the operating method is also very important in real operation.
1. For parts with large treatment allowances, in order to have better thermal dissipation conditions during treatment and to avoid heat concentration, symmetrical treatment should be used during treatment. If a 90 mm thick part must be treated at 60 mm, if one side is ground immediately after a mill on one side and the last size is treated, the flatness is 5 mm; If a repeated symmetrical treatment is used, each side is treated twice by twice at the final size can guarantee that the flatness reaches 0.3 mm.
2. If there are several cavities on the parts of the plate, it is not advisable to use the method of processing the controls of a cavity and a cavity during treatment, as this will easily cause a constraint unequal on the parts and the deformation. The multiple layer treatment is used, and each layer is treated throughout the cavity at the same time, then the following layer is treated to make parts uniformly subjected to stress and reduce deformation.
3. Reduce the cutting force and the cutting heat by changing the quantity of cut. Among the three elements of the cutting dose, the quantity of the backtracking tool has a large impact on the cutting force. If the machining allowance is too large and the cutting force of the tool is too large, it will not only deform the parts, but will also affect the rigidity of the machine pin and reduce the sustainability of the tool. If you reduce the amount of knife to take the back, this will considerably reduce productivity. However, high -speed grinding is used in CNC machining, which can overcome this problem. While reducing the quantity of back-food tool, as long as the diet is increased accordingly and the speed of the tool-tool is increased, the cutting force can be reduced and the processing efficiency can be ensured .
4. The order of the knife is also carefully considered. Approximate treatment emphasizes the improvement in treatment efficiency and continuing the elimination rate per unit of time. That is to say that excess material on the surface of the white is cut at the fastest and shortest speed, and essentially form the geometric profile required for the finish. The emphasis on high precision and high quality in the treatment of the finish is, and the smooth grinding is suitable. Since the cutting thickness of the cutter teeth gradually decreases from the maximum to zero during grinding, the degree of hardening of the work is considerably reduced and the deformation of the parts is reduced.
5. Parts with thin walls are distorted due to tightening during treatment, and even the finish is inevitable. To minimize the deformation of the part, you can loosen the pressed part before the finish is about to reach the final size, so that the part can be restored to its original condition, then slightly in a hurry, depending on the Same thing that is capable of tightening the part (completely by the feeling of the hand), you can get the ideal treatment effect. In short, the tightening point is preferable to be on the support surface. best.
6. When processing the parts with the belt cavity, try not to let the milling cutter penetrate directly into the rooms like a forest during the treatment of the cavity, which causes a storage space insufficient Fire cutter and a smooth withdrawal of fleas, causing overheating of the parts to be overheated, develop and collapse. First drill the drilling hole with a drill of the same size or the same size larger as cutting cutting, then use the milling cutter to wet. Alternatively, a decreasing spiral procedure can be produced using CAM software.
The main factor affecting the processing accuracy and the quality of the surface of aluminum parts is that the deformation is likely to occur during the treatment of these parts, which requires that the operator has a certain experience and operational skills.