This paper describes the development of a “surface and solid modeler”, which enables impression modelling of casting and forging dies effectively in practice. A solid modeler can deal with solids effectively, but cannot deal with surfaces. So it has weakness in embedding surfaces into a solid, filleting and giving a draft-angle to a solid. The system developed by authors represents solids and composite surfaces in the identical data structurer based on “surface and solid model”, and can perform operations not only between solids but also between a solid and a composite surface.
A piezoelectrically actuated micro positioning table (MPT) which can be retrofitted to enhance the performance of the conventional ceramic grinding machine has been developed. A microcomputer-based control system for the MPT has been established to enable detection of the force acting on the MPT as well as small depth of cut; It has been attested that the increase of force acting on the MPT can be estimated with 1.25N resolution by the increase of control input voltage (CV value) to manipulate the MPT. The experimental results in grinding of ceramics show that the MPT can give better versatility to enable operations such as initial setting up of wheel depth of cut, automated surface grinding, formation of micro profiles on the surface, and in-process compensation of machining errors.
This paper describes the results on the development of a high-speed reciprocating table driven by electromagnetic force. The table is driven for quick acceleration and quick deceleration by the repulsion force due to electromagnetic impulsive force. The force is produced between a coil and the conductive material facing the coil when a powerful current flows through the coil by sudden discharge. The computer-controlled stopping system which already suggested by the authors is applied in order to attain the quick stopping of the table. The table mainly consists of a mobile table, a pair of coils and electric circuits, and a control system for driving. The table is guided by linear bearings through linear shafts supported by stands on the left and right to ensure linear motion on a straight line. For the purpose of inducing an eddy current, two aluminum plates are attached to both table surfaces facing the coils. The motion of the table can be summarized as follows. The table is at first accelerated by the coil set at the stand on one side, and is run freely at a constant high speed. When the table accesses the other coil surface, the discharge current flows through the coil. Then the table stops quickly if the discharge timing is adequately controlled. The repeated motion mentioned above is the principle of the reciprocating table mechanism developed. As the result of the experiments, stable reciprocating motions were ascertained even with varied table speed. In the cutting tests of soft vinyl resin using the developed table, the cut surfaces became smooth with increasing cutting velocity.
One dimensional table unit driven by a sliding screw or a ball screw is made with a laserfeed-back system, aiming at ultra-precision positioning at high speed. In this report, the follow-ing items are clarified by the experiment of PTP proportionalcontrol : (1) With increasing theaxial speed, the sliding screw requires much more energy than the ball screw and this derivesa damping effect to the control system. Therefore, the ball screw shows a sharper response thanthe sliding screw. (2) In case of the simple proportional control, the deviation error (off-seterror) is generated by the quantumization of a D/A converter. By adjusting the proportionalgain, both the deviation error and the dispersion error cannot be decreased at the same time.
A new measurement system of tangential grinding force, applying slip of induction motor, is developed with the inverter which controls rotational speed of induction motor. The rotary encoder is combined with the spindle of motor which drives the axis of grinding wheel and the output of rotary encoder is converted into voltage E with F-V converter. So that E means the rotational speed of motor and slip ΔE of motor is measured with analog signal. In this system, the measurement sensibility and response on the grinding force are improved due to the application of F-V converter and the stabilization of rotational speed of motor for utilization of the inverter. As the result of experiment, it is clear that the grinding power and the tangential grinding force are approximated by linear form with ΔE. In case of this system, tangential grinding force is calculated independently of initial speed Em of motor controlled by the inverter.
A highly precise vertical turntable provided with hydrostatic bearings and radial runout error compensator has been developped. The compensator has two functions of a closed loop differential hydrostatic actuator for positioning a spindle to a nanometer accuracy and a datum roundness error measuring instrument with multiple position sensors. By separating the datum error from the runout error readings, the compensator can overcome the limitation of geometrical datum accu racy. Design philosophy of the turntable spindle system is as follows : (1) Isolation of disturbance sources within the system. (2) Design procedure of bearing pads taking into consideration of the performance of servd valve. (3) Introduction of microprocessor for separating the datum error in rounout error measurment from the runout error readings. Several test results are concluded as follows : (1) The bearing pad dimensions are determined in connecting with servo valve characteristics. (2) The positioning resolution is at least 1 nm and the bandwidth is 250 Hz. (3) Two point roundness measurement method has proved that the compensation accuracy is ± 4.5nm (3 σ). However, correcting the datum error in accordance with the measurement principle, compensation accuracy improved to 6.1nm (2LSB, 5rpm) or 9.15nm (3LSB, 30rpm) in peak to valley.
For the Direct Contour Mapping (DCM) method, a new pattern recognition algorithm of contour lines is proposed. The DCM proposed by the authors is effective for the automatic contour mapping of a solid body, because every contour line is chased on the solid body and the chain code data of the contour line is obtained directly. However, each contour line is a closed curve, and it is difficult for the DCM to measure a solid body which has more than two peaks and therefore, has more than two closed contour lines of the same level. To avoid this difficulty, the property of the chain code data is analyzed, and the shape of the contour line is recognized by a host computer of the automatic contour mapping system. The host computer compares a newly detected contour line with a former one, and when the computer recognizes the change of the shape of the contour line, the system tries to find out an independent contour line of the same level. With the proposed pattern recognition algorithm, the contour map of a solid body having more than two peaks can be obtained automatically.
This paper presents a method of bottom up processing for separating thick lines and hair lines and for recognizing straight lines, circles and arcs. It plays a fundamental and important role in the whole recognition method for mechanical drawings written on the basis of JIS drawing rules. This is the first report preceding other issues such as generating a recognition model, top down verify/modify processing and dimension matching for generation of a 2-D CAD model. First, all original binary image data are classified into two classes, thick and hair lines, with use of line width. Then, they are transformed into skeletons in both classes and after that each skeleton is divided into several segments. Further, based on the geometrical feature of the segments, those of thick lines are classified into straight lines, circles, arcs, etc., and they are transformed into structural representations. Some examples are finally shown.
The study deals with 5-axis control machining of workpieces with sculptured surface like impellers. The 5-axis control machining allows complex workpieces to be produced efficiently and accurately. Then, it is of importance to avoid the collision between tool and workpiece due to the arbitrariness of tool attitude. The system developed in the study generates the collisionfree tool path for workpieces with sculptured surface, based on the CAD/CAM system employing the solid modeling techniques. As a result, the validity of the system is experimentally confirmed.
Laser patterning technique of multi-layer thin film structures was developed as a new fabrication process for the integrated-type amorphous silicon (a-Si) solar cells. It was found that the total output power for an a-Si solar cell submodule using the laser patterning method was 20% higher than that obtained by a conventional patterning method. In laser patterning, optical and three-dimensional thermal analysis of multi-layer structures was performed to determine the selective scribing conditions for each layer of an a-Si solar cell. It was found that each layer of the integrated-type a-Si solar cells can be selectively scribed by a Q-switched YAG laser.
In this report the fundamental analyses of grinding phenomena in very low speed grinding process have been considered in order to investigate the possibility of high accuracy and high quality machining. Main conclusions are as follows : (1) Observation of cutting chips shows that continuous chips are generated in very low speed grinding as same as ones generated in common speed grinding. (2) At wheel speed Vs=14m/s the unique phenomena of wheel wear rate and grinding forces are due to the size effect caused by the change of wheel wear condition. (3) The grinding performance of accuracy and quality at very low wheel speed Vs=0.5m/s is equal with and/or more excellent than that in common speed grinding.
The grinding positions of beginning and ending on the wheel surfaces when a involute spur gear is machined by the whole depth of cut with a rack-tooth worm wheel are geometrically and theoretically analyzed. The effects of operating parameters on the stock removal u per unit area at each part on the wheel surfaces are theoretically discussed. Moreover, it becomes clear that the wheel wear on the wheel surfaces depends on u. Other main results are summerized as follows : (1) As for u on the rack-tooth crest, it is becomes the maximum among the wheel surfaces and increases remarkably at the tip of trailing side on the crest. (2) On the rack-tooth surface, u is larger on trailing side than on leading side, small at the dedendum side on both tooth surfaces and becomes the maximum in the neighborhood of its pitch line. (3) Moreover, u increases when work feed speed is large and decreases when radius of generating rolling circle of worm wheel or number of teeth are large. (4) There is the appropriate work feed speed at which wheel wear on tooth crest becomes the minimum. This appropriate speed becomes higher accompanying the increase of number of teeth.
This paper deals with the relation between the properties of the wheel surface and the surface roughness of the workpiece for various truing and dressing conditions. In addition, the availability of the stick-aided loose abrasive dressing method, in which the loose abrasives are added to the ordinal WA stick method, is discussed. The stick-aided loose abrasive method can form the chip pocket effectively without much damage of CBN abrasives. Cutting edge distribution on the working surface of the wheel can be controlled by a series of dressing/truing operations over a wide range. Good finished surface is obtained as the accumulative cutting edge increases in a certain extent. An excessive re-truing makes the cutting edge too flat, so that a loading of welding type occurs in grinding and a good finished surface is unobtainable under such conditions. Loading increases with soluble type grinding fluids, especially in water-rich dilution and decreases with oil-based grinding fluids in grinding.
The electrolytic-abrasive mirror finishing method has been studied for a cylinder workpiece. However it is not sufficient for a mirror surface with a high shape accuracy and supremely small undulation. In order to finish uniformly for the reference surface, the loci of moving abrasives should be completely uniform or the abrased groove should have an appropriate crossing angles. Furthermore, the toolelectrode should have the flexibility then the toolelectrode is able to be used workpiece with various diameter. In this paper, new method and experimental results for a cylinder workpiece has studied, stressing improved shape accuracy by a control of abrasion motion.
This paper describes the new method of finish roll forming, where the forced displacement is kept in some prescribed amount during processing. The tooth profiles and the tooth deflection before and after finish are measured for the hobbed spur gears, module 5, made of 0.45% carbon steel having JIS quality class 0 to 4. For finishing the optimal finish condition, various characteristics of the finish, such as maximum deformation on tooth profiles, concave error, displacement at tooth tip, pressure angle error and plastic deflection are illustrated and analyzed. The improvement of profile accuracy by the optimal finishing condition are examined for several types of profile error by theoretical analysis. For example if tooth profiles have pressure angle error in positive or negative value and the accuracy of tooth profiles before rolling is lower than JIS quality class 1, this new method will improve the finishing accuracy by JIS quality class difference 1-2.
This paper presents a basic research for improving the dressability of metal bonded CBN wheels. A dressing experiment with CBN grinding segment has been conducted to investigate fundamentally the infuluence of tin content on the dressability of bronze bonded CBN wheels. Main results obtained in this paper are as follows : (1) A remarkable improvement in dressability of bronze bonded CBN wheels is achieved with increasing Sn content R more than about 40 wt%. (2) The removal mechanism of bond surface in dressing high tin bronze bonded wheels with R more than 40 wt% depends on not only ductile removal action such as plastic abrasion and micro cutting, but also brittle removal action such as grain boundary fracture of bond.