Stiffness Enhancement Method for Thin-walled Cavity Components in CNC Machining Based on Process Feature Structure Optimization

doi:10.3969/j.issn.1004-132X.2026.10.021

Abstract

Abstract:

During the CNC milling of aerospace thin-walled cavity components， the large amount of material removal led to insufficient stiffness in regions such as cavity webs， resulting in chatters and reduction of dimensional accuracy. Moreover， suspended webs and similar features were difficult to support with auxiliary fixtures or external vibration suppression devices. To address these issues， a stiffness enhancement strategy for the CNC machining of thin-walled cavity components was proposed based on process feature structure optimization. Dynamic characteristic analysis was conducted to identify weak regions in the structure， and process feature structures were designed based on vibration response amplitudes. Then， response surface methodology was employed to optimize the design of these process feature structures. The accuracy of the response surface model was validated through finite element analysis and modal testing. The results show that the first-order natural frequency of the optimized structure increases by 36.7%， while the vibration amplitude at the center point is reduced by 70.26%. A rough-finish hybrid milling strategy tailored to the process feature structures was proposed， and corresponding tool paths were generated. The experimental results demonstrate that the proposed stiffness enhancement strategy effectively suppresses chatters and improves surface quality during machining.

Key words: thin-walled cavity, process feature structure, response surface, tool path planning, stiffness enhancement

摘要：

在航空薄壁腔体类构件数控铣削加工过程中，由于材料去除量大，导致型腔腹板等部位加工时刚性不足，极易产生颤振和加工精度下降等问题，同时，一些悬空腹板等加工部位也难以采用辅助支承和外部抑振装置。提出了一种基于工艺特征结构优化的薄壁腔体构件数控加工刚度增强策略。对薄壁腔体构件薄弱区域进行了动态特性分析，基于振动响应幅值设计出工艺特征结构；基于响应曲面法进行了工艺特征结构优化设计，通过有限元和模态试验验证了响应曲面函数的准确性，优化后结构的一阶固有频率提高36.7%，中心点振动幅值降低70.26%；提出了适用于工艺特征结构的粗精混合铣削加工方法，生成了针对工艺特征结构的刀具轨迹。试验结果表明，所提出的刚度增强加工策略能够有效避免颤振和提高加工表面质量。

关键词: 薄壁腔体, 工艺结构, 响应曲面, 刀具轨迹规划, 刚度增强

CLC Number:

TH162.1

LI Jiaqi, QI Shutao, ZHENG Shucai, SUN Yuwen. Stiffness Enhancement Method for Thin-walled Cavity Components in CNC Machining Based on Process Feature Structure Optimization[J]. China Mechanical Engineering, 2026, 37(10): 2586-2593.

李佳奇, 齐书韬, 郑书材, 孙玉文. 基于工艺特征结构优化的薄壁腔体构件数控加工刚度增强方法[J]. 中国机械工程, 2026, 37(10): 2586-2593.

Figures/Tables 23

Fig.1 Thin-walled components

Fig.4 Mode shapes

Fig.5 Workpiece position division and frequency response function at each point

Fig.6 Amplitude variation with component position graph

Fig.7 Process feature structural component

Fig.8 Scatter plot of process structure height and natural frequency

Fig.9 Frequency response function curves before and after optimization

Fig.10 Web layered machining diagram

Fig.11 Cavity profile

Fig.12 Layout line generation

Fig.13 Process structure toolpath

Fig.14 Corrugated toolpath

Fig.15 Toolpath before and after optimization

Tab.1 Radial cutting depth and machining time for each area

区域	径向切深/mm	加工时间/s
A-Ⅰ	4	234
B-Ⅰ	6	530
A-Ⅱ	4	791
B-Ⅱ	6	1218
A-Ⅲ	4	2298

Fig.16 Traditional equidistant offset toolpath

Fig.17 Thin-walled parts physical and modal testing site

Fig.18 Comparison of frequency response

Tab.2 Experimental and finite element analysis results

模型		固有频率/Hz
有限元分析	优化前	624
有限元分析	优化后	858
锤击试验	优化前	663
锤击试验	优化后	906

Tab.3 Machining parameters for each machining method

加工方法		主轴转速/ （r·min $- 1$ ）	径向切深/mm	每齿进给/mm	轴向切深/mm
等距偏置刀轨	粗加工	1200	6	0.07	1.0
等距偏置刀轨	精加工	1000	4	0.05	0.5
粗精混合刀轨	粗加工	1200	6	0.07	1.0
粗精混合刀轨	精加工	1000	4	0.05	0.5

Tab.3 Machining parameters for each machining method

加工方法		主轴转速/ （r·min $- 1$ ）	径向切深/mm	每齿进给/mm	轴向切深/mm
等距偏置刀轨	粗加工	1200	6	0.07	1.0
等距偏置刀轨	精加工	1000	4	0.05	0.5
粗精混合刀轨	粗加工	1200	6	0.07	1.0
粗精混合刀轨	精加工	1000	4	0.05	0.5

Fig.19 Machining test site and tool

Fig.20 Comparison of the surface quality of the two machined surfaces

Fig.21 Surface roughness of each area

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