Optimal Structure of Computer Numerical Control Grinding Machine Based on Finite Element Method Simulation and Sensor Technology

Owing to the requirement of ever-increasing machining accuracy in tool machinery, the research on how to optimally design a reliable high-rigidity computer-numerical-controlled (CNC) machine tool is increasing in importance. Conventionally, machine designers carried out design optimization by attempting to maximize only the static stiffness. Nowadays, for highprecision machining, a good machine tool should have high rigidity not only under static stimuli but also under dynamic stimuli. The dynamic rigidity of the machine structure is thus receiving increasing attention. In this study, we propose an integral-stiffness-based optimization methodology for designing the optimal structure of a CNC horizontal machining center (HMC). The proposed novel optimization methodology is mainly based on Taguchi's experimental method, the finite element method (FEM), and gray relational analysis (GRA). In addition, some specifically designed experiments on machine stiffness are performed using displacement sensors to verify the calculation results. The optimization parameters consist of the static stiffness, the first natural frequency, and the dynamic stiffness. Through the use of our proposed methodology, the optimal structural dimensions of the target HMC that give high integral rigidity can be determined. Moreover, the proposed optimization methodology provides a good guide for machine designers to design the high-rigidity structure of a CNC machine tool efficiently and accurately.

Section: Optimization Based On Static Rigiditysupporting

confidence: 68%

“…Recently, with the development of highly rigid machine structures, increasing importance has been attached to the dynamic responses of machines. (19,20) In summary, the optimal consideration of both the static and dynamic stiffnesses of the machine structure is a prerequisite for designing a good machine tool.…”

Section: Introduction and Literature Reviewmentioning

confidence: 99%

Structural Design Optimization of Movable-column Horizontal Machining Center Based on Integral Stiffness Analysis and Sensor Measurement

Wang¹,

Yang²

2023

“…Furthermore, a comparison of the results of this study with those of a similar study for the same target machine is made as follows. In the previous study by Wang et al, (28) the target CNC grinding machine based on the optimization of static stiffness exhibited good static behavior with a maximum static deformation of 0.0131 mm, while in this study, it exhibits slightly worse behavior with a maximum static deformation of 0.0143 mm, about 9% larger. In contrast, the optimal target structure in Ref.…”

Section: Optimal Structure Verification and Comparisoncontrasting

confidence: 45%

“…In contrast, the optimal target structure in Ref. 28 showed a dynamic deformation of 0.486 mm at 35.9 Hz (similar to that of Case 1 in this study), while in this study, it exhibited better dynamic stiffness with a maximum deformation of 0.148 mm at 40 Hz, about 30% smaller. Note that under real cutting conditions, only the dynamic stiffness has a major influence on the final precision of cutting for a machine tool.…”

Section: Optimal Structure Verification and Comparisonsupporting

confidence: 43%

Integral-stiffness-based Optimization Method for Designing a Computer Numerically Controlled Grinding Machine

Wang¹,

Yang²,

Wu³

et al. 2021

Self Cite

New methods of optimizing the design of machines with high stiffness have attracted much attention. Conventionally, machine designers have carried out optimization by attempting to minimize static deformation or maximize static stiffness. Nevertheless, the dynamic behavior of the machine structure plays a deterministic role in the final machining precision. Therefore, we propose in this study an integral-stiffness-based optimization method for designing the optimal structure of a computer numerically controlled (CNC) grinding machine. The proposed novel optimization methodology includes a prototype designed on the basis of know-how and the determination of control parameters based on the mode shape, Taguchi's experimental method based on finite element analysis (FEA), and grey relational analysis (GRA). The target parameters in the optimization are static stiffness, first natural frequency, and dynamic stiffness. Results reveal that the optimal structure of a CNC grinding machine obtained by merely considering the static stiffness exhibits good performance when applying static forces but inferior performance when applying dynamic forces. A good optimization approach for designing a high-precision machine should integrally consider the static stiffness as well as the dynamic stiffness. With our proposed methodology, machine designers can design an optimal high-stiffness structure of a CNC grinding machine more efficiently and accurately.

“…However, the acceptable measurement results of static stiffness for Case B have shown that our simulation results via FEM are convincing. To further verify the correctness of the calculation and measurement results of our target MDMC, we now compare the static stiffness of our target MDMC with that of a large movingcolumn horizontal machining center machine (HMC), (21) as shown in Table 5. It can be seen that the relative error of the calculated static rigidity between MDMC and HMC is 5.8%, whereas the relative error of the measured static rigidity between them is 8.9%.…”

Section: Comparisonmentioning

confidence: 99%

A Novel Design Optimization Methodology for Machine Tools Based on Computer-assisted Engineering and Sensor-based Measurement Techniques

Ma,

Wang,

Yang

2023

Structural rigidity is a crucial factor that determines machining accuracy for computernumerical-controlled (CNC) machines. Therefore, how to design a highly rigid CNC machine tool has been the focus of attention. In response to the rapid changes in various machine tools attributable to market needs, it is necessary to find an efficient way to examine and optimally design their structures. In this study, we propose an optimization methodology based on the finite element method (FEM) and sensor-based measurement to efficiently investigate and obtain an optimal structure with high rigidity of the selected target CNC movable-cross-beam double-column machining center (MDMC). The proposed methodology is mainly composed of the prototype design of a target machine, theoretical investigations via FEM, static as well as dynamic stiffness analysis, experimental measurements based on sensors, investigations on crucial parameters that mostly affect the whole structural strength, and the design of an optimum structure via synthesis and comparison. We found that a reduction as large as 1000 mm in the Z travel of a spindle head causes decreases as large as 69.37% in minimum static stiffness and 37.93% in minimum dynamic stiffness. It is suggested that, for optimally designing our target MDMC, the Z-travel length of the spindle head should be reduced to half the original size. This proposed methodology is a rapid, effective, and economical way to optimally design or modify the structure of a MDMC. It can also be used as an optimization guide of the structural design for other types of CNC machine tool.