Processing technology and optimization of titanium alloy high-precision thin-walled parts
Several considerations on the processing technology and optimization of titanium alloy high-precision thin-walled parts:
1. Consider the structure of the workpiece
When designing the structure of the workpiece, not only the performance of the workpiece should be considered, but also the adaptability of this structure to the processing process should be considered. Different workpiece structures correspond to different processing methods. In order to ensure the processing of thin-walled parts The accuracy is particularly important for the design of the workpiece structure. Generally speaking, the application of thin-walled parts made of titanium alloy plates has high accuracy requirements and use requirements. The deformation of the parts will not only cause difficulties in installation and other processes, and may not complete the design parts. What needs to be done. Therefore, in order to avoid the deformation of the workpiece during the machining process, first, it may be considered to design the workpiece into a symmetrical structure. This structure makes the release of the internal force of the various parts of the workpiece in the machining process synchronous, and avoids the distribution of the internal force. Unequal situation. Second, in the design of the thin plate, as far as possible to ensure that the thickness of the entire thin plate is consistent, and at some corners of the workpiece, because of processing or heat treatment, stress concentration may occur, and the corner design can be transitioned to the structure of the arc , Thereby reducing the deformation of the workpiece.
2. Considering the clamping of the workpiece
Thin-walled parts have a relatively thin thickness and only a low stiffness, that is, the workpiece has a weak ability to resist elastic deformation. Therefore, in the processing of the workpiece, the clamping will also affect the workpiece to a large extent. Deformed. Clamping is mainly used to fix the workpiece, use the clamp to position the workpiece and ensure the stability of the workpiece during processing. Unreasonable clamping position and clamping force will reduce the processing accuracy. Therefore, when choosing the clamping position, try to ensure that each clamping position is in a symmetric relationship, and the selection of clamping force can be adjusted according to the rigidity of the workpiece. When the rigidity of the workpiece is high, you can choose a larger clamping force, but pay special attention to the fact that when the rigidity of the workpiece is low, you must choose the appropriate clamping force, otherwise it will easily cause the workpiece to deform during the processing.
3. Consider from the aspect of heat treatment
The general heat treatment of the workpiece is completed by quenching and artificial aging treatment, and the timing of heat treatment of the workpiece is very important for reducing the deformation of the workpiece. Because when the workpiece is heat-treated, the workpiece will have temperature stress and phase transformation stress inside the workpiece due to its own temperature change, which is the main reason for the deformation of the workpiece. At the same time, the heat treatment can not destroy the mechanical properties of the workpiece, so generally, the timing of heat treatment can be considered before rough machining of the blank. Make the timing of heat treatment as reasonable as possible, so as to ensure the mechanical properties of the workpiece and reduce the deformation caused by the heat treatment of the workpiece.
4. Considering the process method and cutting fluid
In the process arrangement of workpiece processing, first of all, according to the different composition of different types of workpieces, the process arrangement is arranged. Among them, special attention should be paid to analyze the parts of the workpiece that are easily deformed during processing to consider whether it can Through the adjustment of some processes, the deformation of the workpiece is reduced. Secondly, when roughing the workpiece, it is necessary to reserve a large cutting margin at the beginning, and do the work of positioning the reference plane. As the machining of the workpiece progresses, it is necessary to always pay attention to the correction of the reference plane, because the processing The reduction of the margin in the process will inevitably bring about changes in the datum. The choice of cutting fluid is mainly based on the nature of the processing and the processing tool. The reasonable use of cutting fluid according to different process arrangements and tool usage helps to improve the efficiency of workpiece processing.
5. Elimination of residual stress of thin-walled parts
The initial residual stress of thin-walled parts is generally determined by the heating factor of the blank material, and the processing residual stress is generally reflected after the processing of thin-walled parts, so the study of residual stress is worth paying attention to, how to predict The influence of residual stress and how to eliminate the influence of residual stress on the processing quality of parts.
Although the source of residual stress in thin-walled parts is already known, its influence on the deformation of thin-walled parts cannot be accurately determined, because the residual stress of thin-walled parts causes the deformation of thin-walled parts is generally caused by the combination of heating factors and mechanical forces. The result of the role. At present, the control of residual stress is generally to use the currently popular finite element analysis method to establish a finite element model of thin-walled parts, and to use numerical analysis to predict the effect of residual stress. In addition, this method can not only simulate the results of deformation correction of thin-walled parts, but also predict springback.
At present, the methods to eliminate the residual stress of the workpiece blank include pre-stretching, vibration aging, aging annealing and cryogenic treatment. Among these methods, cryogenic treatment is the most successful. Cryogenic treatment can effectively reduce the residual stress in thin-walled parts. At the same time, the treatment can also increase the hardness and strength of the parts, improve the wear resistance of the workpiece, and increase the service life of the parts. In addition, the cryogenic treatment can also ensure the dimensional accuracy of the parts and improve the internal stress distribution in the parts. And to reduce the influence of machining residual stress on the machining deformation of parts, it is still necessary to reduce the cutting heat.