Showing papers by "Katsushi Furutani published in 1999"

Multiple degrees-of-freedom arm with passive joints for on-the-machine measurement system by calibrating with geometric solids

Abstract: To fabricate three-dimensional profiles with high accuracy, on-the-machine measurement is useful. Methods for the on-the-machine measurement by calibration with geometric solids used for references have been developed. In this paper, an arm with passive joints for on-the-machine measurement is proposed. As a prototype, the arm has 4 degrees of freedom (DOF) including two passive joints. The probing system has 7 DOF, including the DOF of the machine tool, in total. Angles of the passive joints are changed by driving the numerically controlled (NC) table and the main spindle of the machine tool, where the arm is mounted. To calculate the optimal posture of the arm for the shape to be measured, a numerical method of the inverse kinematics is also proposed. The arm has enough positioning accuracy to calibrate its posture. Shapes can be automatically measured with the accuracy of micrometer order by the on-the-machine measurement method as well as a commercial three-dimensional (3-D) coordinate measuring machine and a profilometer.

Precision Machining by Feedback of Shape Data (1st Report) -The Basic Concept and Examples of Corrective Machining-

Abstract: Since industrial products have become higher in performance and finer in size, machining with higher accuracy is therefore a necessity. On one hand there is the requirement to machining with high accuracy and on the other there is the need to develop new systems to deal with this necd. In this paper, the authors propose a new concept of machining system with feedback of shape as in positioning with displacement feedback. To manufacture products with high accuracy, the authors have developed a simple and flexible method for an on-the-machine measurement system using calibration with geometrical solids. The authors have also developed a metal surface modification method using a green compact electrode of tungsten carbide powder by EDM in hydrocarbon oil. This process is realized on the same machine under the process of removal EDM and accretion EDM. These two techniques are combined in order to implement the precision machining system by feedback of shape data. Some examples of machining by this system are described. The machining accuracy of ± 20 μm can be achieved for both flat and 2-dimensional shapes by using the proposed system.

A built-in displacement sensor for an impact drive mechanism

Abstract: Some small mobile devices often stick on a base with a magnet. In the proposed method, a base on which a small mobile device runs has a magnetic displacement sensor. The base made from carbon steel is divided into several parts. A Hall device is attached to each division of the base. Because the output of each Hall device depends on the ratio of the contact areas of the mobile device and the divisions of the base, the device position can be measured. An impact drive mechanism device is positioned by using this displacement sensor. The sensitivity and the linearity are 1.51 mm V-1 and 1.56% within 3 mm, respectively. The positioning error for the distance of motion 0.5 mm is 7 µm in standard deviation.

Linear Drive Mechanism for Multiple Shaft Feeding Using Piezoelectric Actuators.

Abstract: This paper deals with a linear drive mechanism for multiple shaft feeding. Though various small linear drive mechanisms have been developed, they are used to feed single shaft. A unit for multiple shaft feeding has been developed by arranging some feeding devices for single shaft. The proposed feeding device consists of clamps, friction devices for each shaft and a driver. Each shaft can be fed forward or backward direction and can be stationary in a cycle. The feeding principle is investigated by using a device for single shaft feeding. Then a device for three shaft feeding is manufactured in trial. The shafts can be driven up to 100 Hz with a constant displacement. The displacement of the shaft is linearly changed over 20 V as the amplitude of the applied voltage to the driver. This mechanism performs similarly to an inchworm mechanism. However, the proposed device needs less number of actuators than the inchworm mechanism because the driver is commonly used for all shafts and the friction device needs no actuator. This mechanism will be applied to a machining unit for the dot-matrix electrical discharge machining.