► Two analysis methods are proposed to determine the cause of dynamic errors. ► The entire frequency range in the analysis could be divided into three subranges. ► The driven component is dominant in ...influencing the error for low frequencies.
In machine tools, the difference between the position of the tool center point and that of position detectors of the control system leads to a dynamic mechanical error, which is obtained as the difference between the feedback-controlled table position and the position of the tool relative to the table (tool–table relative position). In this paper, analysis methods are proposed to roughly determine the component of the mechanical system that causes the dynamic mechanical error. Two methods, a two-encoders method and a four-accelerators method, for investigating the influence of the mechanical component on the dynamic mechanical error are proposed. In both methods, the frequency response function between the feedback-controlled table position and the tool–table relative position is evaluated. By the proposed methods, the dynamic mechanical error of a high-precision machining center in the X and Y directions is analyzed for frequencies up to 200Hz. It was found that the entire frequency range could be divided into three distinct subranges depending on how the component of the mechanical system influences the dynamic mechanical error at different frequencies. The analysis results indicated that in the low-frequency range, the dynamic response of the driven component plays a dominant role in influencing the dynamic mechanical error. Then, the dynamic mechanical error of the experimental machine was measured for small circular motions. The dynamic mechanical error occurred at the micrometer level. The dynamic mechanical error can be estimated from the frequency response function measured by the proposed method.
Development and speed control of water driven stage NAKAO, Yohichi; SUZUKI, Kenji; SANO, Toshiaki ...
Kikai Gakkai ronbunshū = Transactions of the Japan Society of Mechanical Engineers,
01/2014, Volume:
80, Issue:
815
Journal Article
Peer reviewed
Open access
Water driven stage is developed as a linear stage of the ultra-precision machine tool, especially, that is intentionally designed for the machining of small parts in size, such as optical mirrors and ...lenses. The water driven stage is mainly composed of a body of the stage and a table. The table is supported by water hydrostatic bearings and is driven by water hydraulic cylinder. Speed of the stage, determining the feed rate of the diamond turning, can be controlled by the flow rate into the water hydraulic cylinder. The paper deals with speed control of the stage. Mathematical models of the water driven stage and the proportional flow control valve are derived in order to design feedback control system. Performances of the designed feedback control system are verified via experiments and simulations. It is then verified that the steady state error is less than 0.5%. Step responses of the control system with a step input of the external load acting on the table are also tested, showing validity of the designed control system.
In this paper, a dual-beam laser interferometer measurement system for precision machine tools was presented. The straightness measurement module and the angular measurement module were combined to ...form this measurement system such that the operations of precision machine tools, the positioning, vertical straightness, horizontal straightness, pitch and yaw, can be obtained. The resolution of the positioning, straightness and angle has achieved 0.1 nm, 1 nm and 0.1 arcsec, respectively. The performance of this measurement system has been proved by experiments.
In order to restore the dimensional accuracy and performance of machine tools and their parts, and to ensure the continuation of policy research and production tasks, this paper proposes a novel ...repair method of key components of imported high precision machine tools based on remanufacturing technology and artificial intelligence technology. This research combines the advantages of remanufacturing technology, elaborates the application and types of remanufacturing technology, and analyzes and optimizes the repair process of key parts of imported high precision machine tools based on remanufacturing technology. Based on this, the core purpose of this paper has two aspects, on the one hand, using advanced remanufacturing technology to repair the key parts of imported high precision machine tools, and then improve the accuracy and efficiency of machine tools; on the other hand, to ensure the normal progress of scientific research and production work and the smooth completion of scientific research and production tasks in the author's unit. At the same time, the purpose of these two aspects is also to be able to repair and transform the key parts of imported high precision machine tools in a good and fast manner, improve the performance, quality and accuracy of machine tools, so that China can achieve scientific and technological independence and get rid of dependence on foreign technology. The results show that the research in this paper can repair and transform the key parts of imported high precision machine tools through remanufacturing technology, and improve the accuracy and performance of machine tools.
Self-calibration of a Cross Grid Encoder IBARAKI, Soichi; GOTO, Wataru; MATSUBARA, Atsushi ...
Journal of the Japan Society for Precision Engineering, Contributed Papers,
2006/08/05, Volume:
72, Issue:
8
Journal Article
Open access
The cross grid encoder is an optical diffraction grating type encoder to measure two-dimensional position of a optical head by using a grid plate where grids are aligned orthogonal to each other. The ...cross grid encoder can be applied to measure two-dimensional motion errors of high-precision and ultra-precision machine tools, such as the straightness error or the squareness error. As a basis to establish a methodology to measure evaluate motion accuracy of high- and ultra-precision machine tools by using the cross grid encoder, this paper presents a self-calibration scheme of a measurement error of the cross grid encoder caused mainly by the misalignment of grids. The measurement error corresponding to the location on the grid plate is calibrated by comparing three measurements taken with different orientation of the grid plate. It is experimentally validated that the measurement error of the cross grid encoder is reduced by about 85% at maximum by applying the self-calibration and the compensation of measurement errors.
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