The aluminum alloy parts have good mechanical properties, small specific gravity, good corrosion resistance and excellent processability. They are commonly used in universal structural parts and frame parts, which can meet the requirements of mechanical strength and precision, and can be effective. It reduces the weight of the equipment and is therefore widely used in complex parts.
However, the complex aluminum alloy structural parts have complex shapes, many precise matching elements, and high dimensional accuracy requirements.
First, the processing problems faced by complex aluminum alloy parts
In the process of processing complex aluminum alloy structural parts, the deformation of the parts caused by the large material removal margin must be solved first. Because the blank is a bar, a pipe or a thick plate, in order to make the size close to the part itself, it needs to be removed after machining. Most of the margin. Due to the large amount of material removal, the original fiber structure state is completely destroyed, the processing stress is large, and the residual stress after processing is rebalanced, causing deformation of the parts and increasing the processing difficulty.
Another problem that complex aluminum alloy structural parts have to overcome during processing is the stress deformation problem. There are two kinds of residual stresses, one is the initial residual stress and the other is the processing residual stress. The initial residual stress is the relative equilibrium internal stress existing in the aluminum alloy blank. When the excess material is removed, the original stress balance is destroyed and the stress is rebalanced, which may cause the part to deform. The residual stress is the plastic deformation of the area where the tool interacts with the workpiece under the interaction of cutting force, cutting heat or both. The deformation generates residual stress under the influence of other factors.
Insufficient process conditions are another problem that must be solved in the processing of complex aluminum alloy parts. For the processing of complex aluminum alloy parts, four-axis and above machine tools are required, and the machine tool must have high geometric accuracy and good stability.
In the processing of complex aluminum alloy parts, it is necessary to solve the problem of insufficient strength of the base. Due to insufficient rigidity, some parts of complex aluminum alloy parts are elastically deformed under the action of cutting force during the machining process, forming a knife, and rebounding after unloading, resulting in an oversize difference. Because the knife makes the cutting process unstable, it is often accompanied by a vibrating knife, which results in a large vibration pattern on the machined surface, which seriously affects the surface quality of the part.
Second, the cracking method of complex aluminum alloy parts processing problems
In order to ensure the processing quality, the processing deformation problem must be overcome during the processing of complex aluminum alloy parts. Therefore, in the design of the process route, the general principle of “first deformation and post-processing” should be grasped, and the process division, process dimension design, tool and parameter selection, fixture and clamping mode selection, and auxiliary clamping should be based on this.
Most of the machining allowance should be removed during the roughing phase. The grooves, holes, tables, etc. that cause the whole or important local deformation of the part should be pre-machined. In particular, the sidewall opening groove, the through-plane on the circumference, the asymmetric slot structure, etc., these parts will break the original stress balance after processing, causing large deformation of the part, so the general outline should be processed in the roughing stage. For functional holes and slots such as weight reduction with low precision requirements, it can be directly processed to the final size.
The choice of machining tools. In the roughing stage, the goal of high efficiency and low cost is low, and the tool requirements are low. However, due to the large cutting allowance, a large amount of cutting heat is generated, and the residual stress is increased. Therefore, the tool should be kept sharp and sufficiently cooled during processing. In the finishing stage, the tool should be selected to have sufficient rigidity and good wear resistance to ensure dimensional and dimensional tolerance accuracy. The tool should be sharp and the cutting edge should be clean to reduce the cutting force, reduce the cutting heat, and make the cutting process. Smooth and reduce system chatter. Use carbide milling cutters and coated knives as much as possible. When conditions permit, polycrystalline diamond tools are available.
The tooling should be designed reasonably and reliably positioned. The clamping and pressure can meet the clamping requirements and minimize the impact on the deformation of the parts.
A reasonable process route must be established. Due to the complicated structure and high precision, the complex aluminum alloy structural parts must be divided into rough machining, semi-finishing and finishing, and the heat treatment process is interposed in the middle to reduce the influence of residual stress. The allowance between processes should be reasonably distributed according to the structural characteristics of each part, and the finishing allowance should be minimized under the premise that the remaining amount after deformation can be ensured. Dimensional elements with large tolerances should be guaranteed during semi-finishing to reduce the allowance for finishing and reduce the probability of deformation.
For the rough machining of complex aluminum alloy parts, the vise or three-jaw clamp can be used for the purpose of removing the balance. The clamping force should ensure the clamping is reliable. In the case of finishing, in order to ensure the dimensional and dimensional tolerance accuracy, the positioning datum must have a good flatness, so that the positioning surface and the working platform have a good fit. Therefore, before finishing, the process is usually specially arranged to finish the finishing surface to eliminate the deformation of the positioning surface caused by semi-finishing and stress-reduction. The open plane generally selects fitter grinding, and the closed plane selects high-precision machine tool. Milling. When finishing the positioning surface, the vise is usually used for clamping, and the clamping force is required to be small, and the parts are clamped under natural conditions and must not be flattened.
In the finishing stage of complex aluminum alloy parts, multi-face machining is generally required, and thus the clamping method of the tooling positioning is adopted. In order to prevent deformation caused by over-tightening, it is required that the pressing force of the pressing plate be perpendicular to the force receiving surface, and the lateral component force should be avoided as much as possible. When the pressing position is selected, the workpiece should be solid at the force receiving position and in close contact with the positioning tool. There should be no large windows, suspended space, etc., to reduce the influence of the pressing force factor.
When the complex parts of aluminum alloy are processed, the rigidity of some areas is insufficient, which may cause the knife to be accompanied by vibration lines, which seriously affects the size and surface quality of the parts. In order to reduce or even eliminate the knife phenomenon, in addition to optimizing the cutting parameters, it is also possible to increase the auxiliary support method, which can greatly reduce the phenomenon of the knife and the vibration knife, and ensure the dimensional accuracy and surface quality of the parts.
The dimensional change caused by local deformation can be adjusted by the numerical control program. By analyzing the detected data, the advance and retraction compensation programs are added to the program. Through the lifting knife compensation, part of the thickness dimension change caused by the deformation is compensated for, so as to meet the requirements of batch stability.
Due to its complex structure and high precision requirements, complex parts of aluminum alloys should follow the principle of “first deformation, post-processing” for the processing difficulties of complex parts. Under this principle, a reasonable processing route is formulated, equipped with suitable process equipment, and measures such as selecting appropriate process parameters, positioning and clamping methods, correctly processing the finishing positioning surface, increasing auxiliary support, and introducing numerical control program compensation, etc. Thereby effectively solving the processing problem of high-precision complex aluminum alloy.
HS SMART is a long-term enterprise engaged in CNC machining of aluminum alloy parts. It has strong technical force and advanced processing equipment. At the same time, it has an elite technical team with rich theoretical knowledge and practical experience. It is proficient in structural design and product development of aluminum alloy parts. He has accumulated rich experience in the processing of aluminum alloy parts, especially high-precision complex aluminum alloy parts. For many years, he has provided high-quality aluminum alloy parts design and processing services for many corporate customers.