The development of a high-speed spindle measurement system using a laser diode and a quadrants sensor

Reducing the manufacturing time is the trend of precision manufacturing, and the precision of a work-piece is very important for manufacturing industry. High-speed cutting is becoming more widely used and the high-speed spindle is a very important element, whose precision may affect the overall performance of high-speed cutting. Most of the studies on high-speed cutting are focused on the cutting force, the vibration of the spindle and the effects of the spindle's thermal expansion; however, the measurement of the high-speed spindle continues to use the conventional spindle measurement method.As with the measurement of the high-speed spindle, more strict demands are set on the dynamic balance of cutting tools and the bandwidth of the measurement systems when compared with common spindles. The capacitance displacement sensor has been employed for the spindle error test. The precision of the measurement system is limited by the reference (such as a master ball or a master cylinder). Also the capacitance sensor and the reference must be grounded together. This paper presents a simple spindle measurement system using a laser diode and a quadrants sensor, with accuracy up to 1 μm, within 300,000 rpm for various spindles. The system does not need any reference and it is easy to set up. This system can be applied to measure the spindle errors, the spindle speed and the spindle indexing.     

六自由度奈米测量机之量测系统组装及校正

介绍一个六自由度奈米级精度测量机台(行程为25mm×25mm)之量测系统的组装及系统的校正,此六自由度奈米测量机分为两部份,第一部分为利用五根压电致动器所组成的四自由度(Z、θx、θy、θz)补偿平台,用以补偿组装及加工误差.第二部份为利用V型导轨架构成之XY双轴滑轨平台,配合音圈马达之推动,使平台能达到XY轴向之定位...     

The Development and Application of a Planar Encoder Measuring System for Performance Tests of CNC Machine Tools

In this paper, a measuring device with a planar encoder is developed to test the performance of a CNC machine tool. With the assistance of a PC, this system can be employed for both 2D contouring tests and 3D positioning tests for a CNC machine tool. The structure and the principle of the system, the applications for the general 2D contouring test, the drift test, and the specified geometric part path tests. An actual case study on improving the accuracy of machining a cam are described. Finally, a new 3D positioning method using the optic encoder is demonstrated. ID="A1"Correspondance and offprint requests to: Dr W. Jwye, 64 Wenhua Road, National Huwei Institute of Technology, Huwei, Yunlin, Taiwan 632. E-mail: Jywe@sunws.nhit.edu.tw     

Sliding‐mode control of a three‐degrees‐of‐freedom nanopositioner

This paper presents the sliding‐mode control of a three‐degrees‐of‐freedom nanopositioner (Z, θ_x, θ_y). This nanopositioner is actuated by piezoelectric actuators. Capacitive gap sensors are used for position feedback. In order to design the feedback controller, the open‐loop characteristics of this nanopositioner are investigated. Based on the results of the investigation, each pair of piezoelectric actuators and corresponding gap sensors is treated as an independent system and modeled as a first‐order linear model coupled with hysteresis. When the model is identified and the hysteresis nonlinearity is linearized, a linear system model with uncertainty is used to design the controller. When designing the controller, the sliding‐mode disturbance (uncertainty) estimation and compensation scheme is used. The structure of the proposed controller is similar to that of a proportional integral derivative controller. Thus, it can be easily implemented. Experimental results show that 3‐nm tracking resolution can be obtained. Copyright © 2008 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society     

Control of an equipment for fabricating periodic nanostructure

This study presents the control for an equipment that is designed for fabricating periodic nanostructures. This equipment can generate the patterns required for nanostructure production using direct writing laser lithography. The equipment incorporates a direct writing laser lithography instrument, a linear motor-driven long-stroke stage (X, Y), a piezoelectric-driven two degrees of freedom (2-DOF) nano-stage (Y, θ_z), a 3-DOF laser interferometer measurement system, and a system control unit. The working stage of this equipment is combined by a long-stroke stage and a nano-stage; therefore, it can provide long-stroke and high-precision positioning. The feedback signal for this stage is obtained using a 3-DOF laser interferometer measurement system. Integral sliding-mode controllers are used to control the linear motor-driven stage and PID controllers are used to control the piezo-stage for precision positioning. This paper presents the design of the controllers and the control results. Experimental results show that satisfactory writing results can be obtained at a 100 mm/s scan speed.     

New nano-contouring measurement techniques for a nano-stage

Among the most commonly used contouring measurement methods, no measuring techniques have been available with nanometer resolution except for the grating encoder measurement system. Although the grating encoder measurement system can reach the resolution of nanometers for nano-contouring, its resolution and accuracy of measurement are limited by the manufacturing accuracy of the size of the grating etching, the size of the light-spot and the pitch of the grating. When the contouring radius is less then the pitch of the grating, the grating encoder system does not work. So, no measuring instrument could simultaneously measure the nano-stage contouring error. In this paper, three new nano-contouring measurement techniques for a nano-stage have been successfully developed by employing laser interferometers, corner cubes and some developed fixture. By specified light path arrangements, three different setting-ups are described in this paper. The measuring resolution of these techniques is 10 nm. Contouring tests with a very small radius were carried out. A 500 nm radius contouring test result was given. Since the techniques are simple, it is very easy to set up and to carry out the tests, compared to other systems. Also, the setting-up error can be ignored when the contouring radius is small. A Heidenhain measuring system was employed to verify these three new techniques. Good verification results were obtained to prove these systems.     

Application of a diffraction grating and position sensitive detectors to the measurement of error motion and angular indexing of an indexing table

In this paper, two systems for the measurement of the error motion and angular indexing of a rotary indexing table have been developed. A laser diode, a laser holder and a position sensitive detector (PSD) are integrated as a simple measuring device for the measurement of the rotary error without using a precision reference artifact (a cylinder or a sphere), multiple probes or error separation methods. The laser diode is assembled in the laser holder and fixed on the rotary table. The PSD is set up above the laser holder to detect the position of an incident laser beam from the laser diode. When the rotary table rotates, the rotary error changes the direction of the incident beam and also the position of the spot on the PSD. For the measurement of the angular indexing, a reflective diffraction grating and two PSDs are integrated as a high-resolution angle measuring device without using an autocollimator or a laser interferometer system. The diffraction grating is set at the center of the rotary table and reflects an incident laser beam into several diffractive rays. Two PSDs were set up for detecting the positions of ±1st-order diffraction rays. A simple algebraic method is used to solve the angular indexing through an optical analysis. The experimental results showed the feasibility of the proposed test devices.     

Development of automatic regrinding program for PC-based tool grinding machine

The main goal of this development is the PC-based controller setup on the CM2 tool grinding machine. Concerned cutting parameters with know-hows can be transferred to a useful program and then embedded in the PC-based controller. By automatic positioning of probes the automatic procedure can be achieved. An automatic and intelligent PC-based grinding machine for regrinding has been developed in this investigation. With the new machine and automatic procedure, regrinding process will be distinctly simplified. Based on a manual grinding machine CM2, a PC-based controller is integrated in the machine. The know-hows of the regrinding technology have been integrated with a self-developed program. For automatic dimensional inspection a contact probe is utilized as inspection sensor. By the programming and automatic dimensional inspection, the functions of tool regrinding machine have been enhanced greatly.     

A new 2D error separation technique for performance tests of CNC machine tools

The error separation technique is widely adopted for many machine tool performance tests. The most common applications include roughness measurement, straightness measurement and spindle measurement. In this paper, two error-separation technologies, the straightness reversal technique and the semi-reversal technique, are developed. The straightness reversal technique can be adopted for the straightness measurement of a linear axis. The semi-reversal technique can be adopted for setting error separation in a contouring test and in the spindle error measurement. In this paper, mathematical models have been developed. In order to verify the possibility of the semi-reversal technique, related experimental work has been carried out.     

Note: Development of a high resolution six-degrees-of-freedom optical vibrometer for precision stage

A high resolution six degrees of freedom (6-DOF) optical vibrometer is proposed. 6-DOF vibrations can be simultaneously measured using the proposed optical vibrometer, which reduces measurement time and number. The performance of the proposed vibrometer is verified by experiments. The results show that the accuracy of the proposed optical vibrometer is ±30 nm∕200 nm and ±0.04 arcsec∕0.1 arcsec at 1000 Hz.