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Easily solve the processing problems of complex aluminum alloy parts

Aluminum alloy parts have good mechanical properties, small material proportions, good corrosion resistance and excellent manufacturability. They are often used for universal structural parts and frame cnc machining parts, which can not only meet the requirements of mechanical strength and precision, but also be effective Reduce equipment weight, so it is widely used in complex parts.

However, complex aluminum alloy structural parts have complex shapes, many precision matching elements, and high dimensional accuracy requirements. Changhong Precision Editor here introduces the problems faced by complex aluminum alloy structural parts and solutions, hoping to be of benefit to industry friends.

1. Machining problems faced by complex aluminum alloy parts

In the processing of complex aluminum alloy structural parts, the first thing to do is to solve the problem of part deformation caused by large material removal margin. Because the blank is a bar, tube or 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 is completely destroyed, the processing stress is large, and the residual stress is rebalanced after processing, which causes deformation of the parts and increases the processing difficulty.

Another problem to be overcome in the processing of complex aluminum alloy structural parts is the problem of stress and deformation. There are two kinds of residual stress, one is initial residual stress, and the other is processing residual stress. The initial residual stress is the relatively balanced 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 will cause the part to deform. Machining 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. This deformation generates residual stress under the influence of other factors.

Insufficient process conditions are another problem that must be solved during the processing of complex aluminum alloy parts. To process complex aluminum parts, four-axis or more machine tools are required, and the machine tools must have high geometric accuracy and good stability.

It is necessary to solve the problem of insufficient matrix strength during the processing of complex aluminum alloy parts. Due to insufficient rigidity, some parts of complex aluminum alloy parts produce elastic deformation under the action of cutting force during the machining process, forming a relief knife, and rebounding after unloading, resulting in size tolerance. As the tool makes the cutting process unstable, it is often accompanied by vibration of the tool, resulting in large vibration lines on the machined surface, which seriously affects the surface quality of the parts.

Aluminum alloy parts have good mechanical properties, small material proportions, good corrosion resistance and excellent manufacturability. They are often used for universal structural parts and frame parts, which can not only meet the requirements of mechanical strength and precision, but also be effective Reduce equipment weight, so it is widely used in complex parts.

However, complex aluminum alloy structural parts have complex shapes, many precision matching elements, and high dimensional accuracy requirements. Changhong Precision Editor here introduces the problems faced by complex aluminum alloy structural parts and solutions, hoping to be of benefit to industry friends.

1. Machining problems faced by complex aluminum alloy parts

In the processing of complex aluminum alloy structural parts, the first thing to do is to solve the problem of part deformation caused by large material removal margin. Because the blank is a bar, tube or 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 is completely destroyed, the processing stress is large, and the residual stress is rebalanced after processing, which causes deformation of the parts and increases the processing difficulty.

Another problem to be overcome in the processing of complex aluminum alloy structural parts is the problem of stress and deformation. There are two kinds of residual stress, one is initial residual stress, and the other is processing residual stress. The initial residual stress is the relatively balanced 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 will cause the part to deform. Machining 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. This deformation generates residual stress under the influence of other factors.

Insufficient process conditions are another problem that must be solved during the processing of complex aluminum alloy parts. To process complex aluminum alloy parts, four-axis or more machine tools are required, and the machine tools must have high geometric accuracy and good stability.

It is necessary to solve the problem of insufficient matrix strength during the processing of complex aluminum alloy parts. Due to insufficient rigidity, some parts of complex aluminum alloy parts produce elastic deformation under the action of cutting force during the machining process, forming a relief knife, and rebounding after unloading, resulting in size tolerance. As the tool makes the cutting process unstable, it is often accompanied by vibration of the tool, resulting in large vibration lines on the machined surface, which seriously affects the surface quality of the parts.

2.The method of solving the processing problems of complex aluminum alloy parts

In order to ensure the processing quality, the problem of processing deformation must be overcome during the processing of complex aluminum alloy parts. Therefore, when designing the process route, the general principle of “deform first, then process” should be grasped, and process division, process size design, tool and parameter selection, fixture and clamping method selection, auxiliary clamping, etc. should be carried out based on this.
Most of the machining allowance should be removed during the roughing stage. Slots, holes, tables and other parts that cause overall or important local deformation of the part should be processed in advance. Especially the opening grooves on the side walls, the penetrating plane on the circumference, the asymmetrical slot hole structure, etc., these parts will break the original stress balance after processing, causing greater deformation of the parts, so the rough outline should be processed in the roughing stage. For functional holes and slots with low precision requirements such as weight reduction, they can be directly processed to the final size.
Selection of machining tools. In the rough machining stage, high efficiency and low cost are the goal, 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 cutting tool is required to be sharp and sufficiently cooled during processing. In the finishing stage, the selected tool should have sufficient rigidity and good wear resistance to ensure the accuracy of dimensional and geometric tolerances. The tool should be sharp and the cutting edge smooth to reduce the cutting force, reduce the cutting heat, and make the cutting process Stable and reduce system chatter. Try to choose cemented carbide milling cutters and coated cutters. When possible, polycrystalline diamond cutters can be used.

The tooling should be designed reasonably and positioned reliably. The clamping and pressure can not only meet the clamping requirements, but also minimize the influence on the deformation of the parts.

A reasonable process route must be developed. Due to the complex structure and high precision, complex aluminum alloy structural parts must be divided into rough machining, semi-finishing and finishing, and heat treatment processes are inserted in the middle to reduce the influence of residual stress. The allocation of allowances between processes should be based on the structural characteristics of each part, and should be reasonably allocated, and the finishing allowance should be minimized on the premise of ensuring sufficient allowance after deformation. For dimensional elements with larger tolerances, they should be guaranteed during semi-finishing to reduce the removal margin of finishing and reduce the probability of deformation.

The rough machining of complex aluminum alloy parts is aimed at removing the margin, which can be clamped by a vise or three-jaw, and the clamping force should ensure reliable clamping. During finishing, in order to meet the tolerance accuracy of size and form and position, the positioning reference surface must have a good flatness, so that the positioning surface and the working platform have a good fit. Therefore, before finishing, the process is generally arranged to finish the positioning surface to eliminate the deformation of the positioning surface caused by semi-finishing and stress relief. Open planes generally choose fitter grinding, and closed planes choose high-precision machine tools. Milling. When refining the positioning surface, a vise is generally used for clamping, and the clamping force is required to be small, and the parts are clamped in a natural state and must not be knocked flat.

The finishing stage of complex aluminum alloy parts generally requires multi-face machining, so the clamping method of tool positioning and compression is adopted. In order to prevent the deformation caused by excessive compression, the pressing force of the pressing plate is required to be perpendicular to the bearing surface, and the lateral force component is avoided as far as possible. When selecting the pressing position, the workpiece should be solid at the stressed position and in close contact with the positioning tooling. There must be no large windows, hanging, etc., in order to reduce the influence of the pressing force.
When machining complex aluminum alloy parts, due to insufficient rigidity in some areas, it is easy to 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 phenomenon of tool loss, in addition to optimizing the cutting parameters, the method of adding auxiliary supports can also be used, which can greatly reduce the phenomenon of tool loss and vibration, and ensure the dimensional accuracy and surface quality of the parts.

The size change caused by the local deformation can be adjusted through the NC program. Through the analysis of the detection data, the tool advance and retreat compensation programs are added to the program. Through the tool lift compensation, the thickness and dimension changes caused by deformation are partially compensated, so as to meet the requirements of batch production stability.

Due to its complex structure and high precision requirements for aluminum alloy complex parts, the principle of “deform first, then process” should be followed for the processing difficulties of complex parts. Based on this principle, a reasonable machining process route is formulated, with appropriate process equipment, and measures such as selecting appropriate process parameters, positioning and clamping methods, correct processing of finishing positioning surfaces, adding auxiliary supports, and introducing numerical control program compensation, etc. So as to effectively solve the processing problems of high precision and complex aluminum alloy.

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