March 10, 2022
The processing deformation problem of aluminum alloy casings, especially thin-walled casings, is a common technical problem. Therefore, our machining factory must analyze the causes of deformation, and then take corresponding countermeasures to prevent them.
1. The material grade and structural complexity of the aluminum shell will affect the deformation of the shell
The amount of deformation of the CNC machined aluminum shell is related to the complexity of the shape, the aspect ratio and the wall thickness, and is directly related to the rigidity and stability of the material. Therefore, when designing the aluminum shell of the product, the influence of these factors on the deformation of the workpiece should be minimized. Especially in the customization of the shell processing of the parts with larger size, the structure should be reasonable. Before processing, the hardness and porosity of the aluminum alloy material blank should be strictly controlled to ensure the quality of the blank and reduce the deformation of the workpiece caused by it.
2. The deformation of the aluminum shell caused by the machining and clamping of the machining center
When the aluminum shell is processed and the material blank is clamped, the correct clamping surface should be selected first, and then the appropriate clamping force should be selected according to the position of the clamping surface. Therefore, the clamping surface and the force-bearing surface should be consistent as much as possible, so that the clamping force acts on the workpiece. When the clamping force in several directions acts on the workpiece, the sequence of the clamping force should be considered. The clamping force should be applied first to make the workpiece contact the support, and it is not easy to be too large. The main clamping force to balance the cutting force , which should be used in subsequent processes.
3. The deformation caused by the processing parameters of the aluminum shell in the Beijing machining factory
During the cutting process of the machining center machine tool, the shell is subjected to the action of the cutting force, and the elastic deformation corresponding to the direction of the force is generated, which is what we often say in the machining industry. Corresponding measures should be taken in processing parameters and tool selection to deal with such deformation. The tool is required to be sharp during finishing. On the one hand, it can reduce the resistance formed by the friction between the tool and the workpiece, and on the other hand, it can improve the heat dissipation effect of the tool when cutting the workpiece. , thereby reducing the residual internal stress on the workpiece.
It is common to use the single-edge milling method when milling the large surface of thin-walled casing parts. The tool parameters use a larger entering angle and a larger rake angle, in order to reduce the cutting resistance. Because this tool cuts lightly and runs fast, it reduces the deformation of thin-walled parts and is widely used in production. In the process of customizing the processing of thin-walled aluminum shells, a reasonable tool angle is crucial to the magnitude of the cutting force during machining, the thermal deformation generated during the process, and the microscopic quality of the workpiece surface. The size of the rake angle of the tool determines the cutting deformation and the sharpness of the rake angle of the tool. The large rake angle reduces the cutting deformation and friction, but if the rake angle is too large, the wedge angle of the tool will be reduced, the strength of the tool will be weakened, the heat dissipation of the tool will be poor, and the wear will be accelerated. Therefore, when machining aluminum alloy thin-walled cavities, high-speed tools and carbide tools are generally used. The correct choice of tool is the key to deal with the deformation of the aluminum shell workpiece.
In machining, the heat generated by the friction between the CNC machine tool and the workpiece will also deform the workpiece, so high-speed cutting is often selected. In high-speed machining, since the chips are removed in a relatively short time, most of the cutting heat is taken away by the chips, reducing the thermal deformation of the workpiece; secondly, when working in a high-speed machining center, due to the reduction of the softened part of the cutting layer material , It can also reduce the deformation of the aluminum shell processing, which is beneficial to ensure that the shell has the precise size, shape and size. In addition, the cutting fluid of the CNC machine tool machining center is mainly used to reduce the friction and reduce the cutting temperature during the cutting process. Reasonable selection of cutting fluid plays an indispensable role in improving tool durability, surface quality and machining accuracy. Therefore, in order to prevent deformation of parts during processing, special cutting fluids with appropriate concentrations must be used reasonably.
Using a reasonable cutting amount in the CNC machining process is an important part of ensuring the accuracy of the parts. When processing thin-walled aluminum shells with high precision requirements, symmetrical processing is generally adopted to balance the stress generated on the opposite sides and achieve a relatively stable state, and the workpiece will be as flat as possible after processing. However, when a large amount of cutting is adopted in a certain process, the workpiece will be deformed due to the unbalance of tensile stress and compressive stress. The deformation of the thin-walled aluminum shell during cutting on the machining center is multi-faceted. Some factors such as the clamping force when clamping the workpiece, the cutting force when cutting the workpiece, and the elastic deformation and plastic deformation generated when the workpiece hinders the cutting of the tool will make customization The casing is deformed.
4. The deformation of the aluminum shell in the natural state after the machine tool of the machining center is off
After the aluminum shell is finished processing, there is internal stress in the processing part itself, and there is also deformation. To solve such a situation, some workpieces need to be divided into roughing and finishing, that is, after roughing is completed, aging treatment or heat treatment to remove stress, and then finishing.