Measurement of Movement Error and its Compensation for 6-DOF Parallel Mechanism Worktable

2012 ◽  
Vol 523-524 ◽  
pp. 463-468 ◽  
Author(s):  
Yuan Rui Zhang ◽  
Jiang Zhu ◽  
Tomohisa Tanaka ◽  
Yoshio Saito
Keyword(s):  
Machine Tool ◽  
Machine Tools ◽  
Parallel Mechanism ◽  
Coordinate Measuring Machine ◽  
Geometric Error ◽  
Degree Of Freedom ◽  
Positioning Error ◽  
Uncertainty Factor ◽  
Movement Error ◽  
Measuring Machine

In this study, a small, 6-DOF (degree of freedom) parallel mechanism worktable for machine tool was developed. There are a lot of factors that affect the positioning error and the accuracy of the machine tools. The uncertainty in position is mainly due to the rigidity of the structure, the geometric error of parts and assembly errors. It is very difficult to estimate the assembly errors and the link parameter of each part. In this paper, the uncertainty factor in positioning of the worktable was investigated and compensated based on measurement of movement error by using coordinate measuring machine (CMM).

Positioning Calibration of a Parallel Mechanism Worktable with 6-DOF

2014 ◽  
Vol 625 ◽  
pp. 392-397
Author(s):  
Yuan Rui Zhang ◽  
Shigenobu Nagase ◽  
Jiang Zhu ◽  
Tomohisa Tanaka ◽  
Yoshio Saito
Keyword(s):  
Machine Tool ◽  
Parallel Mechanism ◽  
Coordinate Measuring Machine ◽  
Measuring Method ◽  
Inverse Kinematic ◽  
Geometric Error ◽  
Positioning Accuracy ◽  
3 Dimensional ◽  
Movement Error ◽  
Measuring Machine

In this study, a small 6-DOF (degree of freedom) parallel mechanism worktable for machine tool was developed. There are many factors that affect the positioning precision and the accuracy of the machine tool. The uncertainty in position is mainly due to the structural rigidity, the geometric error of the parts and the assembly errors. It is very difficult to estimate the assembly errors and the link parameter of each part. Moreover, it is necessary to make clear the relation of cross talk between each axis for parallel mechanism. In this research, a method to compensate the movement error of worktable based on the measurement result was proposed and discussed. First, in order to measure the positioning accuracy of the worktable a measuring method by using 3-dimensional coordinate measuring machine (CMM) was proposed. After the evaluation, the positioning accuracy of the parallel mechanism worktable, the error of each configuration parameter can be obtained. By the correction of the inverse kinematic program, the improvement of the positioning accuracy of the worktable was confirmed. After calibrating several times, the positioning error became stable within a constant range. It is confirmed that this method to obtain the parameter error is effective, and it is possible to improve the positioning accuracy.

A Technique for Enhancing Machine Tool Accuracy by Transferring the Metrology Reference From the Machine Tool to the Workpiece

2006 ◽  
Vol 129 (3) ◽  
pp. 636-643 ◽  
Author(s):  
Bethany A. Woody ◽  
K. Scott Smith ◽  
Robert J. Hocken ◽  
Jimmie A. Miller
Keyword(s):  
Machine Tool ◽  
Machine Tools ◽  
High Speed ◽  
Large Scale ◽  
Thermal Environment ◽  
Coordinate Measuring Machine ◽  
Shop Floor ◽  
Finished Part ◽  
Measuring Machine ◽  
Monolithic Components

High-speed machining (HSM) has had a large impact on the design and fabrication of aerospace parts and HSM techniques have been used to improve the quality of conventionally machined parts as well. Initially, the trend toward HSM of monolithic parts was focused on small parts, where existing machine tools have sufficient precision to machine the required features. But, as the technology continues to progress, the scale of monolithic parts has continued to grow. However, the growth of such parts has become limited by the inability of existing machines to achieve the tolerances required for assembly due to the long-range accuracy and the thermal environment of most machine tools. Increasing part size without decreasing the tolerances using existing technology requires very large and very accurate machines in a tightly controlled thermal environment. As a result, new techniques are needed to precisely and accurately manufacture large scale monolithic components. Previous work has established the fiducial calibration system (FCS), a technique, which, for the first time provides a method that allows for the accuracy of a coordinate measuring machine (CMM) to be transferred to the shop floor. This paper addresses the range of applicability of the FCS, and provides a method to answer two fundamental questions. First, given a set of machines and fiducials, how much improvement in precision of the finished part can be expected? And second, given a desired precision of the finished part, what machines and fiducials are required? The achievable improvement in precision using the FCS depends on a number of factors including, but not limited to: the type of fiducial, the probing system on the machine and CMM, the time required to make a measurement, and the frequency of measurement. In this paper, the sensitivity of the method to such items is evaluated through an uncertainty analysis, and examples are given indicating how this analysis can be used in a variety of cases.

scholarly journals Positioning Errors Measurement of CNC Machine Tools Based on J-DBB Method

2021 ◽  
Vol 11 (24) ◽  
pp. 11770
Author(s):  
Tao Sun ◽  
Wen Wang ◽  
Zhanfeng Chen ◽  
Yewen Zhu ◽  
Kaifei Xu ◽  
...  
Keyword(s):  
Machine Tool ◽  
Machine Tools ◽  
Degree Of Freedom ◽  
Ball Screw ◽  
Cnc Machine Tools ◽  
Positioning Error ◽  
Cnc Machine Tool ◽  
Spherical Joint ◽  
Cnc Machine ◽  
Positioning Errors

Due to the errors of the servo system and the errors of the ball screw drive system, the positioning errors inevitably occur in the process of CNC machine tools. The measurement of traditional equipment is limited by a fixed measurement radius and a single degree of freedom, which can only be measured within a fixed plane. In this paper, four different positioning errors of CNC machine tools are first measured at full scale by using J-DBB (a modified double ball bar with one spherical joint connecting two bars) method. The J-DBB device uses a three-degree-of-freedom spherical joint as a connecting part, which realizes that the measurement radius can be continuously changed, and the measurement space is a spatial sphere. First, the principle of the J-DBB method is briefly introduced. Next, four typical positioning errors of CNC machine tools are analyzed and examined, which contain the uniform contraction error of ball screw and linear grating, periodic error of the ball screw and linear grating, interference of measurement devices error, and opposite clearance error. In the end, the trajectories of the CNC machine tool spindle with a single positioning error are simulated by using the J-DBB method. The results reveal that this method can be used for the positioning error of machine tools, which helps to better understand the spatial distribution of CNC machine tool errors and provides guidance for the reasonable selection of working areas to improve the machining accuracy of parts.

A Method for Measuring the Systematic Errors of CNC-Machine Tools

2012 ◽  
Vol 271-272 ◽  
pp. 1770-1775
Author(s):  
Qi Gao
Keyword(s):  
Machine Tool ◽  
Machine Tools ◽  
Tool Path ◽  
Laser Interferometer ◽  
Coordinate Measuring Machine ◽  
Calibration Method ◽  
Cnc Machine Tools ◽  
Cnc Machine ◽  
Measuring Machine ◽  
Error Calibration

The method used for measurement and calibration of machine tool errors should be general and efficient. With this method, the machine tool status can be completely identified and its accuracy can be enhanced by software error compensation. The point compensation method can be used as a means for modifying the nominal tool path and on-machine inspection where the machine tool is used as a coordinate measuring machine. The validity of the error calibration method proposed in this' paper was shown using a vertical 3-axis CNC machine with a laser interferometer and a ball bar technique.

scholarly journals Calibration Method of Parallel Mechanism Type Machine Tools

2020 ◽  
Vol 14 (3) ◽  
pp. 429-437
Author(s):  
Keisuke Nagao ◽  
◽  
Nobuaki Fujiki ◽  
Yoshitaka Morimoto ◽  
Akio Hayashi
Keyword(s):  
Machine Tools ◽  
Parallel Mechanism ◽  
Least Squares Method ◽  
Coordinate Measuring Machine ◽  
Calibration Method ◽  
Kinematic Parameter ◽  
Forward Kinematics ◽  
Kinematic Parameters ◽  
Type Machine ◽  
Measuring Machine

This paper proposes a calibration method for a parallel mechanism type machine tool (XMINI, Exechon Enterprises L.L.C.). In this method, the kinematic parameters are calculated using forward kinematics and the least squares method from the results obtained by a coordinate measuring machine. By using an articulated arm coordinate measuring machine (AACMM), we can measure a wide space, and the measuring machine position do not have to be determined strictly. This paper provides a solution for the forward kinematics problem to identify the kinematic parameters. The results from the kinematic parameter calculation are evaluated using the experimental results from an actual machine.

scholarly journals Traceability on Machine Tool Metrology: A Review

2017 ◽  
Author(s):  
Unai Mutilba ◽  
Eneko Gomez-Acedo ◽  
Gorka Kortaberria ◽  
Aitor Olarra ◽  
José Antonio Yagüe-Fabra
Keyword(s):  
Machine Tool ◽  
Manufacturing Process ◽  
Machine Tools ◽  
Nuclear Power ◽  
Measurement Data ◽  
Coordinate Measuring Machine ◽  
Manufacturing Processes ◽  
Scientific Objective ◽  
Measuring Process ◽  
Measuring Machine

Errors during manufacture of high value components are not acceptable nowadays in driving industries such as energy and transportation. Sectors such as aerospace, automotive, shipbuilding, nuclear power, large science facilities or wind power manufacture complex and accurate components that demand close measurements and fast feedback into manufacturing processes. New measuring technologies are already available in machine tools, including integrated touch probes and fast interface capabilities. They shall provide the possibility to measure the workpiece during or after the manufacturing process, maintaining the original setup of the workpiece and avoiding the manufacturing process from being interrupted to transport the workpiece to a measuring position. However, the traceability of the measurement process on a machine tool is not ensured yet and measurement data is still not fully reliable for process control or product validation. Due to the similarity between a coordinate measuring machine and a machine tool, some of the methods applied for a correct assessment of uncertainty in coordinate measuring machines are adapted to the challenges of a machine tool. The scientific objective is to determine the uncertainty on a machine tool measurement and, in this way, convert it into a machine integrated traceable measuring process. This paper reviews the fundamentals of machine tool metrology.

scholarly journals Study of Machining of Gears with Regular and Modified Outline Using CNC Machine Tools

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2913
Author(s):  
Rafał Gołębski ◽  
Piotr Boral
Keyword(s):  
Machine Tools ◽  
Coordinate Measuring Machine ◽  
Optical Microscope ◽  
Numerical Control ◽  
Cnc Machine Tools ◽  
Cnc Milling ◽  
Cnc Machine ◽  
Cylindrical Gears ◽  
Measuring Machine ◽  
Five Axis

Classic methods of machining cylindrical gears, such as hobbing or circumferential chiseling, require the use of expensive special machine tools and dedicated tools, which makes production unprofitable, especially in small and medium series. Today, special attention is paid to the technology of making gears using universal CNC (computer numerical control) machine tools with standard cheap tools. On the basis of the presented mathematical model, a software was developed to generate a code that controls a machine tool for machining cylindrical gears with straight and modified tooth line using the multipass method. Made of steel 16MnCr5, gear wheels with a straight tooth line and with a longitudinally modified convex-convex tooth line were machined on a five-axis CNC milling machine DMG MORI CMX50U, using solid carbide milling cutters (cylindrical and ball end) for processing. The manufactured gears were inspected on a ZEISS coordinate measuring machine, using the software Gear Pro Involute. The conformity of the outline, the tooth line, and the gear pitch were assessed. The side surfaces of the teeth after machining according to the planned strategy were also assessed; the tests were carried out using the optical microscope Alicona Infinite Focus G5 and the contact profilographometer Taylor Hobson, Talysurf 120. The presented method is able to provide a very good quality of machined gears in relation to competing methods. The great advantage of this method is the use of a tool that is not geometrically related to the shape of the machined gear profile, which allows the production of cylindrical gears with a tooth and profile line other than the standard.

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.

scholarly journals Performance of a five-axis machine tool as a coordinate measuring machine (CMM)

2016 ◽  
Vol 10 (5) ◽  
pp. JAMDSM0076-JAMDSM0076 ◽  
Author(s):  
Md Mizanur RAHMAN ◽  
Rene MAYER
Keyword(s):  
Machine Tool ◽  
Coordinate Measuring Machine ◽  
Measuring Machine ◽  
Five Axis
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