scholarly journals Analysis of Dynamic Characteristics for Machine Tools Based on Dynamic Stiffness Sensitivity

Processes ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 2260
Author(s):  
Chunhui Li ◽  
Zhiqiang Song ◽  
Xianghua Huang ◽  
Hui Zhao ◽  
Xuchu Jiang ◽  
...  
Keyword(s):  
Machine Tool ◽  
Dynamic Characteristics ◽  
Machine Tools ◽  
Dynamic Stiffness ◽  
Variable Stiffness ◽  
Structural Vibration ◽  
Dynamic Experiment ◽  
Machine Tool Structure ◽  
Analysis Experiment ◽  
Five Axis

Dynamic parameters are the intermediate information of the entirety of machine dynamics. The differences between components have not been combined with the structural vibration in the cutting process, so it is difficult to directly represent the dynamic characteristics of the whole machine related to spatial position. This paper presents a method to identify sensitive parts according to the dynamic stiffness-sensitivity algorithm, which represents the dynamic characteristics of the whole machine tool. In this study, two experiments were carried out, the simulation verification experiment (dynamic experiment with variable stiffness) and modal analysis experiment (vibration test of five-axis gantry milling machine). The key modes of sensitive parts obtained by this method can represent the position-related dynamic characteristics of the whole machine. The characteristic obtained is that the inherent properties of machine-tool structure are independent of excitation. The method proposed in this paper can accurately represent the dynamic characteristics of the whole machine tool.

Optimized Design and Performance Study of High Speed Five-Axis Machine Tools

2020 ◽  
Author(s):  
Tzu-Chi Chan ◽  
Jyun-Sian Yang
Keyword(s):  
Machine Tool ◽  
Dynamic Characteristics ◽  
Machine Tools ◽  
High Speed ◽  
Spectral Response ◽  
Work Piece ◽  
Static And Dynamic Characteristics ◽  
Five Axis ◽  
Speed Accuracy ◽  
Machine Structure

Abstract With the development of machine tools trending toward high precision, intelligence, multi-axis, and high speed, the improvement of the processing performance and rigidity of the machine is considerably important. The objective of this study is to design of a high-speed five-axis moving-column machine tool and perform structural analysis and optimization. We study the static and dynamic characteristics of the five-axis machine tool, design and improve the mechanical structure, and optimize the structural configuration of the machine. The entire machine structure is further analyzed and enhanced to improve its static and dynamic characteristics, including static rigidity, modal, transient, and spectral response characteristics. The static and dynamic characteristics of the machine structure directly affect the machine processing performance, and further affect the work piece precision machined by the tool. Through this study, the design technology for speed, accuracy, and surface roughness of the machine tool are further improved.

Study on Dynamic Stiffness of Machine Tool with Consideration of Friction Damping in Guide

2012 ◽  
Vol 497 ◽  
pp. 68-72 ◽  
Author(s):  
Miki Shinagawa ◽  
Eiji Shamoto
Keyword(s):  
Machine Tool ◽  
Friction Force ◽  
Machine Tools ◽  
Design Method ◽  
Dynamic Stiffness ◽  
Testing Machine ◽  
Variable Stiffness ◽  
Major Influence ◽  
Chatter Stability ◽  
Friction Damping

The purpose of this study is to acquire design method of machine tools with higher dynamic stiffness and consequently higher chatter stability. This study focuses on stiffness of main structures and friction damping in guide of a machine tool, because stiffness and friction damping are considered to have major influence on the dynamic stiffness. A special testing machine with variable stiffness and friction was developed to clarify effects of the stiffness of main structures and the friction in guide on the dynamic stiffness and therefore the chatter stability. The stiffness of main structures and the friction in guide were changed experimentally, and it was clarified that the optimal friction force exists at every stiffness condition, and that higher stiffness does not always lead to higher stability.

scholarly journals Effect of Time-Varying Moving Structures on the Spatial Accuracy of Five-Axis Machine Tools

2021 ◽  
Author(s):  
Tzu-Chi Chan ◽  
Jyun-Sian Yang
Keyword(s):  
Machine Tool ◽  
Dynamic Characteristics ◽  
Machine Tools ◽  
High Speed ◽  
Time Varying ◽  
Spatial Accuracy ◽  
Static And Dynamic Characteristics ◽  
Five Axis ◽  
Speed Accuracy ◽  
Machine Structure

Abstract Machine tools are constantly in motion during machining; however, studies have not considered the effect of the dynamic and static characteristics of the machine caused by the movement of the structure over time. In this study, the time-varying moving structure in the spatial coordinate arm is analyzed to improve the spatial accuracy of the motion of a five-axis machine tool in the cutting area. The objective is to design a high-speed five-axis moving-column machine tool and to perform structural analysis of spatial accuracy. We studied the static and dynamic characteristics of a five-axis machine tool, designed and improved its mechanical structure, and optimized its structural configuration. With further analysis, the entire machine structure was enhanced to improve its static and dynamic characteristics. The static and dynamic characteristics of the machine structure were found to directly affect its processing performance and the precision of the workpiece machined by the tool. Through this study, the design technology for speed, accuracy, and surface roughness of the machine tool was further improved.

An Attempt of Error Tracing and Compensation Method of the Linkage Error of Five-Axis CNC Machine Tool

2018 ◽  
Author(s):  
Zhong Jiang ◽  
Jiexiong Ding ◽  
Qicheng Ding ◽  
Li Du ◽  
Wei Wang
Keyword(s):  
Machine Tool ◽  
Machine Tools ◽  
Manufacturing Industry ◽  
Complex Surface ◽  
Compensation Method ◽  
Cnc Machine ◽  
Linkage Error ◽  
Error Tracing ◽  
Five Axis ◽  
Five Axes

Nowadays the five-axis machine tool is one of the most important foundations of manufacturing industry. To guarantee the accuracy of the complex surface machining, multi-axis linkage performance detection and compensation of five-axis machine tools is necessary. RTCP (Rotation Tool Center Point) is one of the basic essential functions for the five-axis machine tools, which can keep the tool center with the machining trajectory when five axes move synchronously. On the basis of RTCP function, a way to detect multi-axes linkage performance of five-axis machine tools is briefly introduced, and linkage error model is built in accordance with the topological structure of machine tool. Based on the feature of the linkage errors of the five-axis machine tool, the error tracing and compensation method is proposed. Some simulations and experiments that verify the error tracing method could locate the linkage error category are established. Therefore, a new attempt to detect and compensate the linkage error of the five-axis machine tool is provided in this paper.

Table-Based Volumetric Error Compensation of Large Five-Axis Machine Tools

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
Jennifer Creamer ◽  
Patrick M. Sammons ◽  
Douglas A. Bristow ◽  
Robert G. Landers ◽  
Philip L. Freeman ◽  
...  
Keyword(s):  
Machine Tool ◽  
Error Compensation ◽  
Machine Tools ◽  
Data Gathering ◽  
Measurement Data ◽  
Geometric Error ◽  
Compensation Method ◽  
Geometric Errors ◽  
Simultaneous Generation ◽  
Five Axis

This paper presents a geometric error compensation method for large five-axis machine tools. Compared to smaller machine tools, the longer axis travels and bigger structures of a large machine tool make them more susceptible to complicated, position-dependent geometric errors. The compensation method presented in this paper uses tool tip measurements recorded throughout the axis space to construct an explicit model of a machine tool's geometric errors from which a corresponding set of compensation tables are constructed. The measurements are taken using a laser tracker, permitting rapid error data gathering at most locations in the axis space. Two position-dependent geometric error models are considered in this paper. The first model utilizes a six degree-of-freedom kinematic error description at each axis. The second model is motivated by the structure of table compensation solutions and describes geometric errors as small perturbations to the axis commands. The parameters of both models are identified from the measurement data using a maximum likelihood estimator. Compensation tables are generated by projecting the error model onto the compensation space created by the compensation tables available in the machine tool controller. The first model provides a more intuitive accounting of simple geometric errors than the second; however, it also increases the complexity of projecting the errors onto compensation tables. Experimental results on a commercial five-axis machine tool are presented and analyzed. Despite significant differences in the machine tool error descriptions, both methods produce similar results, within the repeatability of the machine tool. Reasons for this result are discussed. Analysis of the models and compensation tables reveals significant complicated, and unexpected kinematic behavior in the experimental machine tool. A particular strength of the proposed methodology is the simultaneous generation of a complete set of compensation tables that accurately captures complicated kinematic errors independent of whether they arise from expected and unexpected sources.

A Complete, Continuous, and Minimal Product of Exponentials-Based Model for Five-Axis Machine Tools Calibration With a Single Laser Tracker, an R-Test, or a Double Ball-Bar

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
Peng Xu ◽  
Benny C. F. Cheung ◽  
Bing Li
Keyword(s):  
Machine Tool ◽  
Machine Tools ◽  
Rigid Bodies ◽  
Error Model ◽  
Laser Tracker ◽  
Calibration Model ◽  
Transformation Matrices ◽  
Double Ball Bar ◽  
Ball Bar ◽  
Five Axis

Calibration is an important way to improve and guarantee the accuracy of machine tools. This paper presents a systematic approach for position independent geometric errors (PIGEs) calibration of five-axis machine tools based on the product of exponentials (POE) formula. Instead of using 4 × 4 homogeneous transformation matrices (HTMs), it establishes the error model by transforming the 6 × 1 error vectors of rigid bodies between different frames resorting to 6 × 6 adjoint transformation matrices. A stable and efficient error model for the iterative identification of PIGEs should satisfy the requirements of completeness, continuity, and minimality. Since the POE-based error models for five-axis machine tools calibration are naturally complete and continuous, the key issue is to ensure the minimality by eliminating the redundant parameters. Three kinds of redundant parameters, which are caused by joint symmetry information, tool-workpiece metrology, and incomplete measuring data, are illustrated and explained in a geometrically intuitive way. Hence, a straightforward process is presented to select the complete and minimal set of PIGEs for five-axis machine tools. Based on the established unified and compact error Jacobian matrices, observability analyses which quantitatively describe the identification efficiency are conducted and compared for different kinds of tool tip deviations obtained from several commonly used measuring devices, including the laser tracker, R-test, and double ball-bar. Simulations are conducted on a five-axis machine tool to illustrate the application of the calibration model. The effectiveness of the model is also verified by experiments on a five-axis machine tool by using a double ball-bar.

Design and Kinematic Analysis of a Novel Machine Tool With Four Rotational Axes and One Translational Axis

2019 ◽  
Vol 141 (11) ◽  
Author(s):  
Song Gao ◽  
Jihong Chen ◽  
Shusheng Liu ◽  
Xiukun Yuan ◽  
Pengcheng Hu ◽  
...  
Keyword(s):  
Machine Tool ◽  
Kinematic Analysis ◽  
Machine Tools ◽  
Inverse Kinematics ◽  
Kinematics Analysis ◽  
Rotary Axes ◽  
Machining Quality ◽  
New Type ◽  
Kinematic Performance ◽  
Five Axis

Abstract Due to their superior machining quality, efficiency, and availability, five-axis machine tools are important for the manufacturing of complicated parts of freeform surfaces. In this study, a new type of the five-axis machine tool was designed that is composed of four rotary axes as well as one translational axis. Given the structure of the proposed machine tool, an inverse kinematics analysis was conducted analytically, and a set of methods was then proposed to address the issues in the kinematic analysis, e.g., the singularity and multi-solution problems. Compared with traditional five-axis machine tools, which are typically composed of three linear axes and two rotary axes, the proposed machine tool exhibited better kinematic performance with machining parts with hub features, such as impellers, which was validated by simulations and real cuttings.

Modal Testing for Heavy Machine Tool Using Active Excitation

2014 ◽  
Vol 536-537 ◽  
pp. 1326-1332 ◽  
Author(s):  
Bo Luo ◽  
Bin Li ◽  
Xin Yong Mao ◽  
Hui Cai
Keyword(s):  
Machine Tool ◽  
Machine Tools ◽  
Inertial Force ◽  
Modal Testing ◽  
Modal Parameters ◽  
Part Quality ◽  
Machine Tool Structure ◽  
Machining Speed ◽  
Heavy Machine ◽  
Large Machine

For application in large machine tools, the machined part quality, accuracy as well as machining speed depende greatly on the dynamics of the structure. In this paper, an active-excitation modal analysis (AEMA), using inertial force of the moving slider to excite the structural modes, is proposed. Modal parameters of the machine tool structure estimated by AEMA are experimentally validated. Since the artificial excitation produced by elaborate excitation equipment is replaced by the inertial force of the slider, the proposed method is much more practical and economical than traditional methods.

Research on High Performance Direct-Driving Motor Applied to Swivel Spindle Head

2014 ◽  
Vol 701-702 ◽  
pp. 874-878
Author(s):  
Shao Hsien Chen ◽  
Chin Mou Hsu ◽  
Kuo Lin Chiu ◽  
Chu Peng Chan
Keyword(s):  
Renewable Energy ◽  
Machine Tool ◽  
Machine Tools ◽  
High Performance ◽  
Cnc Machine Tools ◽  
Cnc Machine ◽  
Positional Accuracy ◽  
Maximum Torque ◽  
Five Axis

Swivel spindle head is a key component used in five-axis machine tool of high performance and is of great importance in application and design. Nowadays, more and more components are manufactured by high performance multi-axis CNC machine tools, such as components of spaceflight, renewable energy and automobile, etc. Therefore, high performance machine tools of multiple axes are more and more urgently demanded, while Swivel spindle head is one of the most important components for a multi-axis machine tool. Hence, Swivel spindle head is one of the key to developers multi-axis machine tool . The study explores the highly responsive direct-driving motor able to drive the spindle head to rotate with multi-driving rotary technology. The dual-driving motor rotates via multi-driving units, generates torsion that magnifies and eliminates its clearance, and then drives the spindle head to rotate. Results of the test show that the completed machine tool can meet the standards of dual axis rotary head with high preformation in, no matter, speed, distance, positional accuracy, repeated accuracy or maximum torque, etc.

Experimental Research Regarding the Influence of Hydraulic Resistances on the Hydrostatic Guideways Stiffness

2014 ◽  
Vol 657 ◽  
pp. 475-479
Author(s):  
Marius Pascu ◽  
Gheorghe Stan
Keyword(s):  
Machine Tool ◽  
Hydraulic Resistance ◽  
Experimental Research ◽  
Machine Tools ◽  
Dynamic Stiffness ◽  
Experimental Results ◽  
Graphical Form ◽  
Experimental Setup ◽  
Experimental Database ◽  
Supply Circuit

A very important factor for the hydrostatic guideways is given by the presence of the restrictor on the supply circuit, whose hydraulic resistance may have important effects on the lubricant film behaviour and implicitly, on the static and dynamic stiffness of the system. This paper presents a new method of experimental research regarding the hydrostatic guideway stiffness, depending on the hydraulic resistances values which supply each pocket. During the experiments which approach the influence of the hydraulic resistances values of the restrictors on the hydrostatic guideway stiffness, a centered constant loads of 20, 50 and 100 [daN] was used. The experiments were carried out on an experimental setup composed of an open hydrostatic guideway, having the pocket dimensions of 150x88 [m, supplied with liquid under pressure through means of a pack of adjustable restrictors. The obtained experimental results are presented in both tabular and graphical form and constitute an experimental database which can be used by the machine tools designers and manufacturers. The paper contains recommendations regarding the usage of hydraulic resistances values depending on the machine tool type and size. Also, from the obtained results, recommendations can be made with regard to the type of restrictors to be used, so that the lubricant filtration grade is comprised between admissible values.

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