使机床切削点动柔度最大值在整个工作频率范围内最小，是机床实现无颤振稳定切削和高精度切削加工的要求，也是对其进行动态优化设计所应达到的目标。基于模态柔度和能量分布的机床结构动态优化设计原理，实现了一种以降低切削点交叉动柔度值为目标的优化方法。该方法利用切削点交叉动柔度与模态柔度的关系，首先寻找薄弱模态，再分析薄弱模态上各部件和环节的能量分布，确定该模态上的薄弱环节，然后在一定的约束条件下，改进这些环节的设计参数，从而实现优化目标。以某型万能工具铣床为例，在整机建模分析计算的基础上，阐述了该优化方法的具体应用。通过模态柔度和能量分布计算，判明该机床的薄弱环节是横梁-水平主轴体系统，针对薄弱环节设计参数的改进实现其质量和刚度的优化，优化后的静柔度和模态柔度都有较大的降低，而固有频率则相应提高，切削点动柔度的最大值降低近18%。并在此基础上进行结构改进设计，改进前后机床的谐响应分析和切削试验对比结果表明优化方法有效地改善了机床的动态性能，再生颤振稳定性得到大幅提高。
To minimize the maximum compliance at cutting point across all working frequency ranges is the requirement for machine tool to achieve minimum chance of machining chatter and high precision machining, which is also the objective that dynamic optimization design of machine tool should be attained. A dynamic optimum method that aims at decreasing the compliance at cutting point is developed and analyzed according to the principles of dynamic optimization design based on modal flexibility and energy distribution for machine tool. By the relationship between compliance and modal flexibility to indicate weak modals, focusing on the weak modals, the energy distributions of components and links are analyzed to determine the weak parts and links, the optimum design can be realized by improving the design parameters of corresponding parts and links under certain constraints. For a universal tool milling machine as an example, based on modeling analysis and computation of machine tool, the specific application of the optimization method are described. By calculation of modal flexibility and energy distribution, the weak link of the machine is judged to be the system consisted of crossbeam and horizontal spindle body, the optimization of mass and stiffness can be realized by improving design parameters of the weak link, the optimized static flexibility and modal flexibility are greatly reduced, while natural frequencies are increased correspondingly, and the maximum value of compliance at cutting point decreased by nearly 18%. On this basis, the structure improvement design is carried out, and the comparative results of harmonic response analysis and the cutting test between the original and improved machine tool demonstrate that the dynamic characteristics of machine tool are effectively improved and cutting stability for regenerative chatter is greatly increased.
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