Non-uniform machining allowance planning method of thin-walled parts based on the workpiece deformation constraint

Abstract

In order to reduce the machining deformation of thin-walled parts during milling, a non-uniform allowance planning method for thin-walled parts based on workpiece deformation constraint with the idea of adding materials in reverse material removal sequence is proposed in this paper. Firstly, a cutting force threshold calculation method is proposed according to the finite element method. The cutting force threshold at different positions is calculated by obtaining the local stiffness characteristics at the cuttercontact (CC) point under the constraint of allowable deformation. And then, the maximum machining allowance at the CC point is calculated depending on the cutting force model. Considering that the stiffness of the workpiece is position-dependent and affected by material removal, the stiffness of the workpiece is updated by adding elements in the reverse cutting direction, and the stock of finishing is obtained by surface fitting. Experimental results show that compared with the traditional uniform allowance method, the error of the proposed method is reduced by about 83%, which can effectively reduce the deformation and improve the machining accuracy.

Enhancing Chatter Stability for Milling Thin-Walled Blades by Designing Non-Uniform Allowance

“…(2) Machining surface topography analysis The surface morphology after machining of the two process strategies is shown in Figure 10, and the vibration pattern on the surface of the blade basin e.g., Figure 10a-A surface and blade suction e.g., Figure 10a-B surface is very significant when using the In fact, some scholars have already done a lot of basic work on improving the rigidity of the workpiece itself through non-uniform allowance. Reference [36] facing complex thin-walled blade parts, based on the theory of regenerative vibration analysis, established a comparison chart of the stability lobe of uniform allowance and non-uniform allowance. Theoretically, it shows that non-uniform allowance is beneficial to improve the milling stability of the blade and reduce the cutting vibration of the blade during the cutting process.…”

“…However, this method is not suitable In fact, some scholars have already done a lot of basic work on improving the rigidity of the workpiece itself through non-uniform allowance. Reference [36] facing complex thin-walled blade parts, based on the theory of regenerative vibration analysis, established a comparison chart of the stability lobe of uniform allowance and non-uniform allowance. Theoretically, it shows that non-uniform allowance is beneficial to improve the milling stability of the blade and reduce the cutting vibration of the blade during the cutting process.…”

“…The findings demonstrate that the technique expertly suppresses the chattering of thin-walled workpieces and attains a high stability limit [35]. Ultimately, the procedure for adjusting the process stiffness of thin-walled components is achieved by applying the method with non-uniform allowances [36][37][38][39]. Built upon the above studies, this thesis centers around how the traditional design of thin-walled parts can produce a certain inhibitory effect.…”

Study on The Stability and Experimental Study of Non-uniform Allowance Chattering of Thin-Walled Parts Based on ɛ Influence Factor

“…Tian et al [14] determined and optimized the state of semi-finish machining allowance allocation for thin-walled workpieces based on structural stiffness, modal finite element analysis and eigenvalue sensitivity analysis methods. Zhang et al [15] established a margin planning scheme by local stiffness combined with finite element cutting force as a threshold value. Petracek et al [16] and Xin et al [17] used the relationship between depth of cut and rotational speed to optimize the distribution of machining allowances and to reduce chatter, where Petracek et al [16] designed the corresponding spindle speed optimization procedure.…”

Numerical evaluation of cutting strategies for thin-walled parts

“…When the machining allowance left by the roughing operation is removed by a single pass the machining allowance is equal to the width of cut. A large machining allowance gives a higher local stiffness of the workpiece at the cutting point but an increased cutting force, therefore a compromised machining allowance should be selected 3 , 8 . Moreover, the spindle speed should be carefully tuned to avoid tooth-passing frequencies that are close to the workpiece natural frequencies 9 .…”