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. Here, I will introduce the problems and solutions faced by complex aluminum alloy structural parts. I hope it will be helpful 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 removed, 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 processing, causing the size to exceed the tolerance range.
2. In order to ensure the quality of the
processing of complex aluminum alloy parts, the problem of processing
deformation must be overcome during the processing of complex aluminum alloy
parts. Therefore, the general principle of "deform first, then
process" should be grasped when designing the process route. In order to
carry out process division, process size design, tool and parameter selection,
fixture and clamping method selection, auxiliary clamping, etc. 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 interspersed 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 deformation
caused by over-pressing, it is required that the pressing force of the pressing
plate should be perpendicular to the force-bearing surface, and try to avoid
generating lateral force components. When selecting the pressing position, the
workpiece should be solid at the force-bearing position and be in close contact
with the positioning tooling. There must be no large windows or hanging in the
air 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 letting, 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 letting 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 dimension change
caused by the deformation is partially compensated, so as to meet the mass
production stability requirements.
JY Machinery is an enterprise engaged in
CNC machining of aluminum alloy parts for a long time. 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,
proficient in the structural design and product development of aluminum alloy
parts, Has accumulated rich experience in the processing of aluminum alloy
parts, especially high-precision and complex aluminum alloy parts. Over the
years, it has provided high-quality aluminum alloy parts design and processing
services for many corporate customers.
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