Feedrate Optimization for Machine Tool Control Subject to Contour Error Constraints

1989 ◽  
Author(s):  
F. Imamura ◽  
H. Kaufman
Keyword(s):  
Machine Tool ◽  
Control Subject ◽  
Contour Error ◽  
Feedrate Optimization

Contour Controller Design for Cubic Parallel Machine Tool

Manufacturing ◽  
2003 ◽  
Author(s):  
Sungsoo Kim ◽  
Seung Hwan Lee ◽  
Daehie Hong ◽  
Woo Chun Choi ◽  
Jae-Bok Song
Keyword(s):  
Machine Tool ◽  
Machine Tools ◽  
Estimation Method ◽  
Parallel Machine ◽  
Control Algorithms ◽  
Contour Error ◽  
Contour Control ◽  
Contouring Accuracy ◽  
Parallel Machine Tools ◽  
Parallel Machine Tool

In machining processes, contouring accuracy is usually more important than tracking performance. In order to reduce the contour error, there have been many contour control algorithms for conventional machine tools, which noticeably improve their contouring accuracy. However, the available contour control algorithms cannot be directly applied to the parallel machine tools. The dynamic characteristics of the parallel machine tools are not consistent inside workspace and unsymmetrical disturbances can be imposed on any axis. Due to these, mismatched dynamics cause unwanted contour error. In this paper, we present a contour control algorithm for the cubic parallel machine tool that employs the parallel mechanism for its moving table, which can be also applied to a general parallel manipulator. The contour error estimation method for free-formed curve trajectory is proposed and the relation between the contour error vectors in joint and Cartesian spaces is considered. In order to show the validity of the algorithm, the contour control simulations and experiments are made for various contour trajectories with the cubic parallel machine tool. The results show that the proposed controller reduces the contour error considerably both in joint and Cartesian spaces.

Postprocessor algorithm and feedrate optimization for nine-axis milling machine tool with twin cutters

2019 ◽  
Vol 103 (5-8) ◽  
pp. 1745-1757
Author(s):  
Dongdong Song ◽  
Fei Xue ◽  
Jun Zhang ◽  
Cunfan Zou ◽  
Wanhua Zhao ◽  
...  
Keyword(s):  
Machine Tool ◽  
Milling Machine ◽  
Feedrate Optimization

An On-Machine Error Measurement System for Micro-Machining

2007 ◽  
Author(s):  
Shih-Ming Wang ◽  
Han-Jen Yu ◽  
Yi-Hung Liu ◽  
Da-Fun Chen
Keyword(s):  
Machine Tool ◽  
Measurement System ◽  
Error Compensation ◽  
Model Comparison ◽  
Contour Error ◽  
Machining Accuracy ◽  
Error Measurement ◽  
Micro Machining ◽  
Machine Error ◽  
Machining Errors

Technology development trends towards the ability to manufacture ever smaller parts and feature sizes with increased precision and decreased cost. Micro machining is one of the important manufacturing methods to fulfill the requirements from the industry. The objective of this paper is to develop an on-machine error measurement system that can identify the micro machining errors for error compensation so that the machining accuracy of a meso-scale machine tool (mMT) can be enhanced. Because of the difficulty in handling and repositioning the miniature workpiece, the error measurement system should be non-contact and on-machine executable. To meet this requirement, a vision-based error measurement system integrating image re-constructive technology, camera pixel correction, and model comparison algorithm error was developed in this study. The proposed measurement system consists of a CCD with CCTV lens, a precision 3-DOF platform, image re-construction sub-system, and contour error calculation sub-system. By adopting Canny Edge Detection algorithm and camera pixel calibration method, the contour of a machined workpiece can be identified and compared to the pixel-based theoretical contour model of the workpiece to determine the micro machining errors. Because the system does not have to remove the machined workpiece from the CNC machine tool, errors due to re-installing and re-positioning can be avoided. To prove the feasibility of the developed algorithm and system, measurement results obtained from the vision-based measurement system were compared with the measurements of CMM, and error compensation experiment conducted on a 3-DOF mMT was also conducted. The results have shown the good feasibility and effectiveness of the developed system.

Integration of Geometric and Mechanistic Models of NC Machining Into an Open-Architecture Machine Tool Controller

2000 ◽  
Author(s):  
Robert B. Jerard ◽  
Barry K. Fussell ◽  
Mustafa T. Ercan ◽  
Jeffrey G. Hemmett
Keyword(s):  
Machine Tool ◽  
Nc Machining ◽  
Cutting Process ◽  
Open Architecture ◽  
Mechanistic Models ◽  
Machining Processes ◽  
Modeling And Control ◽  
Feedrate Optimization ◽  
Novel Methods ◽  
And Control

Abstract A great deal of research has been done during the last twenty years on the modeling and control of NC machining. Despite the promise of substantial productivity improvements these methods are sparsely used outside their academic birthplaces. We believe that Open-Architecture Controllers (OAC) are the key to unlocking this unfulfilled potential. We describe the implementation of novel methods for feedrate optimization which utilize a commercially available OAC. In this paper an example is given of how substantial improvements in machining processes can be achieved by implementing geometric and mechanistic models of the cutting process on an OAC. These benefits should provide motivation for a more universal adoption of OACs.

Proposal of a machining test to evaluate dynamic synchronization error of rotary and linear axes with reversal of rotation direction

2021 ◽  
pp. 1-16
Author(s):  
Qingzhao Li ◽  
Soichi Ibaraki ◽  
Wei Wang
Keyword(s):  
Machine Tool ◽  
Coordinate System ◽  
Numerical Control ◽  
Synchronization Error ◽  
Free Form ◽  
Contour Error ◽  
Surface Geometry ◽  
Rotation Direction ◽  
Machining Test ◽  
Five Axis

Abstract The five-axis machining of a free-form surface often contains the reversal of a rotary axis' rotation direction with linear axis synchronized with it. This paper proposes a machining test to quantitatively evaluate the influence of the reversal of rotation direction on the surface geometry. In the five-axis machining, the trajectory of tool position and orientation is firstly given in the workpiece coordinate system by the CAM (Computer-aided Manufacturing) software, and the CNC (Computerized Numerical Control) system converts it to the machine coordinate system to calculate command trajectories. This paper clarifies that the tool path smoothing in the machine coordinate system can potentially cause a large contour error because of the dynamic synchronization error of rotary and linear axes. Although some academic works in the literature presented the smoothing in the workpiece coordinate system, many commercial CNC systems still employ the smoothing in the machine coordinate system, partly because machine tool users or makers do not clearly see how significant this influence can be on the machining accuracy. The proposed machining test enables a user to quantitatively evaluate it. The machining experiment shows that the geometric error of the finished test piece was as large as 0.16 mm under the conventional smoothing in a commercial CNC system, which can be significantly larger than the influence of other typical geometric errors of a five-axis machine tool. This paper shows, by numerical simulation, that the smoothing in the workpiece coordinate system can completely eliminate this contour error.

Influence of Nonlinear Friction and Disturbance in the Control of a Mechatronic System: CNC Machine Tool Application

2011 ◽  
Author(s):  
Liz K. Rincon ◽  
Joa˜o M. Rosario
Keyword(s):  
Machine Tool ◽  
Cutting Force ◽  
Viscous Friction ◽  
Numerical Control ◽  
Machining Process ◽  
Contour Error ◽  
Nonlinear Friction ◽  
Cnc Machine ◽  
Mechatronic Systems ◽  
High Speeds

The CNC (Computer Numerical Control) machine tools are complex mechatronic systems applied to the manufacture with high precision and high speeds. To achieve high accuracy and operational efficiency, the disturbance and friction, which occur during machining process, should be reduced as low as possible. This paper develops an analysis of influence by cutting force and friction effect in the control of machine tool based on the CNC dynamic model and parameters identification. For this purpose, the study focuses on Coulomb and Viscous nonlinear friction and the external disturbances. The analysis uses control position error, contour error, and stability to determine the influence of friction and disturbance. The results show that Viscous friction has more critical influence on system than the Cutting force and Coulomb. The work contributes in recognizing which parameters have greater influence on the machine behavior through dynamic analysis with the identification strategy, in order to design and improve the control structure for a real CNC system.

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