Characterization of Kinematic Error Model Consistency for Five-Axis Machine Tools

2018 ◽  
Author(s):  
Le Ma ◽  
Douglas A. Bristow ◽  
Robert G. Landers
Keyword(s):  
Machine Tool ◽  
Machine Tools ◽  
Error Model ◽  
Data Sets ◽  
Kinematic Error ◽  
Interior Space ◽  
Error Models ◽  
Wide Range ◽  
Kinematic Error Model ◽  
Five Axis

New metrology tools, such as laser trackers, are enabling the rapid collection of machine tool geometric error over a wide range of the workspace. Error models fit to this data are used to compensate for high-order geometric errors that were previously challenging to obtain due to limited data sets. However, model fitting accuracy can suffer near the edges of the measurable space where obstacles and interference of the metrology equipment can make it difficult to collect dense data sets. In some instances, for example when obstacles are permanent fixtures, these locations are difficult to measure but critically important for machining, and thus models need to be accurate at these locations. In this paper, a method is proposed to evaluate the model accuracy for five-axis machine tools at measurement boundaries by characterizing the statistical consistency of the model fit over the workspace. Using a representative machine tool compensation method, the modeled Jacobian matrix is derived and used for characterization. By constructing and characterizing different polynomial order error models, it is observed that the function behavior at the boundary and in the unmeasured space is inconsistent with the function behavior in the interior space, and that the inconsistency increases as the polynomial order increases. Also, the further the model is extrapolated into unmeasured space, the more inconsistent the kinematic error model behaves.

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.

scholarly journals Impact of Model Complexity in the Monitoring of Machine Tools Condition Using Volumetric Errors

2020 ◽  
Vol 14 (3) ◽  
pp. 369-379
Author(s):  
Kanglin Xing ◽  
◽  
J. R. R. Mayer ◽  
Sofiane Achiche
Keyword(s):  
Machine Tool ◽  
Recognition Rate ◽  
Error Model ◽  
Model Complexity ◽  
Model Parameters ◽  
Machine Error ◽  
Error Models ◽  
Tool Condition ◽  
Volumetric Errors ◽  
Five Axis

The scale and master ball artefact (SAMBA) method allows estimating the inter- and intra-axis error parameters as well as volumetric errors (VEs) of a five-axis machine tool by using simple ball artefacts and the machine tool’s own touch-trigger probe. The SAMBA method can use two different machine error models named after the number of model parameters, i.e., the “13” and “84” machine error models, to estimate the VEs. In this study, we compare these two machine error models when using VE vector directions and values for monitoring the machine tool condition for three cases of machine malfunctions: 1) a C-axis encoder fault, 2) an induced X-axis linear positioning error, and 3) an induced straightness error simulated fault. The results show that the “13” machine error model produces more focused concentrated VE directions but smaller VE values when compared with the “84” machine error model; furthermore, although both models can recognize the three faults and are effective in monitoring the machine tool condition, the “13” machine error model achieves a better recognition rate of the machine condition. This paper provides guidelines for selecting machine error models for the SAMBA method when using VEs to monitor the machine tool condition.

Measuring Path without Tool Center Point Function for B-Type Five-Axis Machine Tool

2013 ◽  
Vol 284-287 ◽  
pp. 493-497
Author(s):  
Chen Hua She ◽  
Wen Yuh Jywe ◽  
Jheng Jie Huang
Keyword(s):  
Machine Tool ◽  
Machine Tools ◽  
Simulation Software ◽  
Free Form ◽  
Motion Error ◽  
Center Point ◽  
Wide Range ◽  
Assembly Error ◽  
Five Axis ◽  
Free Form Surfaces

Five-axis machine tools with three linear axes and two rotary axes can produce complex products with free-form surfaces requiring a high degree of precision. However, motion errors of each axis and its assembly error are accumulated in the positioning error of the cutting tool relative to a workpiece. There are many devices reported in the literature on the identification of kinematic errors based on the measurement of the motion error. According to the measurement paths in the ISO draft, ISO/CD 10791-6, the kinematic tests can be applicable to different configurations of five-axis machine tools. However, the advanced controller with tool center point (TCP) function is required while performing kinematic tests. This paper proposed the methodology of generating measurement path without TCP function for B-type five-axis machine tool. The developed module can transform the measuring path into an NC program used for lower hand controller. Verification using VERICUT solid cutting simulation software demonstrated the veracity of the generated five-axis NC code. The proposed methodology is applicable in a wide range of five-axis machine tool configurations; however, further testing with actual measuring applications will be required for further verification.

Accuracy enhancement of kinematic error model of three-axis computer numerical control machine tools

2016 ◽  
Vol 231 (11) ◽  
pp. 2021-2030 ◽  
Author(s):  
Mostafa Pezeshki ◽  
Behrooz Arezoo
Keyword(s):  
Machine Tools ◽  
Laser Interferometer ◽  
Error Model ◽  
Numerical Control ◽  
Accurate Estimation ◽  
Kinematic Error ◽  
Positioning Errors ◽  
Volumetric Errors ◽  
Kinematic Error Model ◽  
Kinematic Errors

Accurate estimation of volumetric errors is an important issue in machining operations. For this purpose, a kinematic error model is used to characterize machine tool’s related errors on its workspace. In this research, it is shown that when measuring the linear and positioning errors using a laser interferometer, part of the angular errors are converted to linear and positioning errors and their magnitudes are overestimated. These values are calculated twice in the models which use homogeneous transformation matrix since Abbe’s principle is not considered. In this article, a kinematic error model is proposed which eliminates this overestimation. This model’s methodology is based on rigid body kinematic and errors measurement by laser interferometer and can be generalized for all three-axis machine tools. A software package is developed to integrate the kinematic errors with the NC-codes. A workpiece is machined in the virtual environment and compared with a workpiece machined in real environment. It is shown that the kinematic error model developed in this research predicts the kinematic errors more accurately.

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.

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.

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.

scholarly journals Prospects of Upgrade of the Main Drives of CNC Machine Tools Using Mechatronic Modules

2020 ◽  
Author(s):  
V.V. Goman
Keyword(s):  
Machine Tool ◽  
Electric Motor ◽  
Machine Tools ◽  
Machine Building ◽  
Cnc Machine Tools ◽  
Final Decision ◽  
Cnc Machine ◽  
Advantages And Disadvantages ◽  
Wide Range ◽  
Technical Specifications

This article observes the principles of construction and operation of the belt drives with detached electric motor and the drives with motor spindle. It also describes the characteristics of the elements used in spindles. In choosing a spindle, one proceeds from the primary and secondary requirements for the machine tool: rotation speed, power output, hardness, workspace dimensions, design complexity, application area, option of repair and replacement, and cost. The article considers the advantages and disadvantages of the spindles with additional mechanic gears and the motor spindles. As an example, we compare variants of upgrade of the «16M30F3» machine tool’s main drive. As a result, the following conclusions were made: motor spindle has more advantages than standard drive, but it is way more expensive and its repair is more difficult. Hence, this spindle type is only applicable to machine tools with high standards of quality and performance. Belt-driven spindle is special for easy repair and a wide range of technical specifications: one can choose multiple motor variants for one drive; again, it is much cheaper than motor spindle. However, final decision on spindle should concern the main requirements for the machine tool, workplace dimensions, application of the machine tool and, possibly, financial restrictions. Keywords: CNC machine tool, motor spindle, mechatronics, machine building, electric drive, electric motor, motion control, built-in motor.

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