Study on Generation and Optimization Methodology of On-Machine Measurement Schemes for Multi-Axis CNC Machine Tool

2017 ◽  
Author(s):  
Zhao Bohan ◽  
Gao Feng ◽  
Li Yan ◽  
Zhang Dongya ◽  
Zhang Wanli ◽  
...  
Keyword(s):  
Machine Tool ◽  
Large Scale ◽  
Coordinate Measuring Machine ◽  
Measuring Error ◽  
Cnc Machine Tool ◽  
Cnc Machine ◽  
Real Time Control ◽  
Position Detection ◽  
Volumetric Errors ◽  
Measuring Machine

Quality Control (QC) is one of the most important phases in the production process. In tradition, the workpiece must be inspected for dimension and shape errors in the QC lab or Coordinate Measuring Machine (CMM) after being machined, which is time-consuming and labor-intensive, especially for large scale parts. Thus the only practical way to do that is to migrate the critical primary inspection operations upstream from the QC lab or CMM to the production floor, and that’s what On-Machine Measurement (OMM) does. OMM technology can inspect the workpiece on its operating station by motion control and the position detection function of CNC machine tool, by which the measuring error caused by the misalignment between measuring datum and manufacturing datum can be avoided accurately. Therefore, it is a feasible way to achieve the real-time control of the manufacturing process and improve the manufacturing accuracy and efficiency. The servo axes of multi-axis CNC machine tool might be redundant for being used in OMM, which will result in that one measurement task could be done by different servo motion schemes. In addition, the map between the machine accuracy and measuring accuracy has not been found out previously. Thus, how to determine metering schemes to measure a workpiece with high accuracy and efficiency is one of the most important problems and also a hotspot for everybody. To solve this problem, a generation method of task-oriented OMM scheme is proposed. Utilizing multi-body system theory and transformation of homogeneous coordinates, a function relationship between the geometrical characteristic of workpiece as independent variables and motions of machine tool as dependent variables is established. All possible metering schemes are obtained by analyzing the solution of functional equation. Then the performance of measurement scheme can be evaluated by comparing the measuring errors of each scheme after building a mapping relationship between the machine tool volumetric errors and measuring errors. In the end, a case study was accomplished, and the correctness and efficiency of the methodology has been verified.

Machining Based Geometric Error Estimation Method for 3-Axis CNC Machine

2019 ◽  
Vol 889 ◽  
pp. 469-474
Author(s):  
Trung Kien Hoang ◽  
Nguyen Minh Duc Ta
Keyword(s):  
Machine Tool ◽  
High Accuracy ◽  
Geometric Error ◽  
Numerical Control ◽  
Cnc Machine Tool ◽  
Cnc Machine ◽  
Simple Method ◽  
Volumetric Errors ◽  
Measuring Machine ◽  
Cutting Path

Computer numerical control (CNC) machine tool plays an extremely significant role in any manufacturing industry due to its automation and high accuracy. Keeping the CNC machine tool at its highest performance to meet the demand of high accuracy machining is always significant. To maintain the accuracy of a machine tool over the time, it is important to measure and compensate the geometric error, one of the main error source of machine tool, especially when the machine get old. There are totally 21 geometrical errors in a 3-axis machine tool including three translational errors and three rotational errors for each axis and three perpendicular error (Squareness) within three axes of the machine. This paper presents an economical and simple method for measuring the geometric error of a 3-axis CNC machine tool based on the machining of actual samples. Three samples for each axis will be machined following a design cutting path. The samples will then be measured using a coordinate measuring machine (CMM). The collect data will be used for estimating the geometric errors. The volumetric errors will be then computed and verified through machining of 3D geometries.

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.

Volumetric Errors Prediction of CNC Machine Tool Based on the Laser Interferometer

2013 ◽  
Vol 694-697 ◽  
pp. 1822-1828
Author(s):  
Hai Feng Lin ◽  
Zhi Ping Guo ◽  
Zhi Yong Song ◽  
Da Wei Liu ◽  
Yong Zhong Qiao
Keyword(s):  
Machine Tool ◽  
Laser Interferometer ◽  
Cnc Machine Tool ◽  
Cnc Machine ◽  
Volumetric Errors

The volumetric errors modal is built with the coordinate errors of each axis of CNC machine tool through the laser interferometer. The volumetric errors in the workspace are calculated with the errors prediction modal. With the calculated results of volumetric errors, the errors tendency of CNC machine tool can be predicted. Besides, the specific accuracy testing projects can be conducted by the errors areas taken care more. The main errors of CNC machine tool will be tested rapidly and efficiently.

Design and Implementation of an Embedded PLC System with Applied-Information Technology

2014 ◽  
Vol 685 ◽  
pp. 401-404
Author(s):  
Xiao Juan Shi
Keyword(s):  
Machine Tool ◽  
Integrated Design ◽  
Ladder Diagram ◽  
Cnc Machine Tool ◽  
Single Chip ◽  
Cnc Machine ◽  
Real Time Control ◽  
Design Environment ◽  
Compact Structure ◽  
Time Control

To overcome the shortcomings of external PLC (Programmable Logic Controller) and soft PLC being widely employed in switch control of CNC machine tool, an embedded PLC system was developed by integrating AVR single chip ATMEGA169, PC bus technique and dual port RAM. Both hardware circuit and software of the PLC system were designed and implemented. The software of Industrial PC was developed by using ladder-diagram IDE (Integrated Design Environment) based on the platform of Borland C++ Builder. In this environment, it can fulfill edit, compilation and communication function of ladder-diagram file. It also can monitor and diagnose PLC running status. This developed embedded PLC system has the characteristics of compact structure, high communication and reliability. It can effectively satisfy real-time control requirements of CNC machine tool.

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.

Application of Ant Colony Algorithm to Volumetric Thermal Error Modeling and Compensation of a CNC Machine Tool

2012 ◽  
Vol 170-173 ◽  
pp. 3487-3490
Author(s):  
Qian Jian Guo ◽  
Qing Wen Qu ◽  
Jian Guo Yang
Keyword(s):  
Machine Tool ◽  
Error Compensation ◽  
Ant Colony Algorithm ◽  
Error Modeling ◽  
Ant Colony ◽  
Machining Accuracy ◽  
Cnc Machine Tool ◽  
Cnc Machine ◽  
Volumetric Error ◽  
Volumetric Errors

Volumetric errors are the major contributor to the dimensional errors of a workpiece in precision machining. Error compensation technique is a cost-effective way to reduce volumetric errors. Accurate modeling of volumetric errors is a prerequisite of error compensation. In this paper, a volumetric error model was proposed by using neural networks based on ant colony algorithm. Finally, a volumetric error compensation system was developed based on the proposed model, and which has been applied to a CNC machine tool in daily production. The results show that the volumetric errors are reduced and the machining accuracy of the machine tool is improved.

Accuracy Analysis of Machining Process Using a Spindle Probe and a CMM to Reduce the Scrap

2005 ◽  
Author(s):  
Yongjin Kwon
Keyword(s):  
Machine Tool ◽  
Measurement Data ◽  
Coordinate Measuring Machine ◽  
Machining Process ◽  
Inspection Time ◽  
Cnc Machine ◽  
Part Quality ◽  
Post Process ◽  
Measuring Machine ◽  
Touch Probe

In-process part inspection using a spindle touch probe has gained a significant importance, mainly because parts can remain on the machine without disrupting the machine setup while inspection is being conducted. This practice leads to a shorter inspection time, improved part accuracies, and reduction of scraps. Recently, intense domestic and international competition has put more importance on part quality in terms of producing parts right the first time and maintaining the consistent quality standards. A literature review revealed that a comparative analysis between in-process gauging using a touch probe and post-process inspection using a coordinate measuring machine (CMM) to ascertain part quality has not been adequately studied. Therefore, there is a need for a study to measure the characteristics of the two inspection techniques. To address the problem, cutting experiments were conducted and measurement data were analyzed using a state-of-the-art CNC machine, a CMM, a touch probe, and a high-precision ballbar system. The experimental data show that machined features and touch probe measurements are affected by the inherent shortcomings in machine tool structure, suggesting a machine tool capability analysis be undertaken in tune with the required tolerance specifications prior to machining operations, rather than solely relying on the touch probe inspection for part quality assessment.

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