This paper deals with the development of the die-finishing robotic system which is controlled by the CAD/CAM system. This system consists of the host computer, the robot controller, the grinding condition controller, the grinding tools and the exclusive 7-axis robot. A tool path, tool postures at grinding points and grinding conditions are generated in the host computer of CAD/CAM system by means of the simulation of surface conditions, in which a grinding phenomenon is theoretically analyzed. These informations are integrated into a robotic driving data. The robot controller controls motions of the exclusive 7-axis robot on the basis of a robotic driving data. Similarly, the grinding condition controller controls normal grinding forces and circumferential speeds by means of the grinding tool equipped with an air cylinder and a motor. As the result of applying this robotic system to a die-finishing process, it is proved that this system enables to keep a surface quality after finishing as good as one by usual finishing method (manual finishing) and reduces a die finishing time by 70%.
Speedy and accurate positioning is important for mechatronics products. It is necessary for optimum design to consider mechanical vibration and control. Control designs with mechanical vibrations have two problems : One is a difficulty to input suitable vibration characteristics, the other is an increase in the degree of an equation. Vibration characteristics influence system stability and collocation. This paper describes the analysis system for vibration control using FEM analysis. Mechanical vibrations are analyzed by FEM easily. This analysis system reads modal parameters from FEM output file and control block diagrams are input in dialogue. The analysis results are frequency response, step response and root locus. So it is possible to achieve optimum design for control with a mechanical system having multi-degrees of freedom.
The surface structures of Ni introduced by polishing with diamond paste, electric discharge machining, cutting tool machining and laser beam machining were observed with a transmission electron microscope. Observations were made from directions both vertical and parallel to machined surfaces. Surface structure can be classified into three component substructures. The first one, within a depth smaller than several μm, is specific for each of machining processes. This provides information for the phenomenon which took place in the front of the machined material. The second one in the depth up to around 200μm is cellular structure of dislocations. Cells increase their size gradually with depth and finally turn to dislocation trangles. Sizes and shapes of cells, and their orientation misfit show the history of stress condition. The surface quality by each machining was compared by evaluating the stress induced during machining processes. The last one in the depth larger than 200μm which is composed of tangled dislocations shows an extension of affected zone of machining.
This paper describes a method of improving velocity of the precise positioning mechanism (IDM : Impact Drive Mechanism) utilizing rapid deformations of piezoelectric elements. While the IDM has an ability of very minute motion of several nanometers, the maximum velocity is not as fast as positioning mechanisms using ball-screw or friction drive. By controlling friction applying inertial force vertical to the traveling direction, the movement per one step is increased and the cycle time is reduced. With the friction control, the returning acceleration can be 20 times and velocity, about 10 times as large as those without friction control.
In this research, a snag grinding was performed on a 410 stainless steel with two different alumina wheel types under constant load, using a specially made grinding machine. The variation of grinding characteristics such as metal removal rate and grinding force with the progress of grinding has been studied. On the other hand, the protrusion height and wear flat area of abrasive grains on the working surface of wheel were measured to discuss the results obtained on grinding characteristics. A close correlation was found among the variation of abrasive protrusion height, metal removal rate and tangential grinding force. Also, it was known that the wear area of grains increases with increasing grinding time. The attritious wear was accompanied with reductions of metal removal rate and tangential grinding force. Self-sharpening recovered the abrasive protrusion height and diminished the percent wear flat; this enhanced to improve the metal removal rate and a cutting action by an individual abrasive grain.
Bending moment produced on the vertical section of a workpiece is experimentally investigated under wet grinding. Measured results are compared with the theoretical ones obtained by a finite element method. The thermal deformation of a workpiece attracted by a magnetic chuck is also calculated considering the film boiling phenomenon of grinding fluid and the results are compared with the profiles of ground surfaces. The main results obtained are as follows: (1) When the film boiling does not occur, the grinding fluid effectively restricts the thermal deformation; therefore, the workpiece of good straightness can be easily obtained. (2) When the film boiling occurs under up-grinding, the cooling action is still effective in restricting the thermal deformation, but it is not effective under down-grinding. Therefore, the profiles of wet-down ground surfaces are almost the same as dry ground surfaces.
A description is made to clarify the cutting mechanism of micro drill machining, and the tool dynamometer for micro drill machining, which is a measuring device required for setting the optimum machining conditions. The drill diameters covered by this tool dynamometer are from 0.08 mm to 0.04 mm. In order to distinguish the usage in accordance with the size of diameters, two types of tool dynamometers were made experimentally. Tool dynamometer of TYPE-I was made experimentally for micro drills up to 0.08 mm in diameter with the exception of 0.04 mm in diameter, and micro bearings were employed. Tool dynamometer of TYPE-II was made experimentally for micro drills of 0.04 mm in diameter, and pivot bearing were used. Both of the two types of tool dynamometers are markedly characterized by the capability to measure simultaneously the thrust and torque among the fine cutting forces generated when machining the micro drills. For the performance evaluation of the tool dynamometers which were made experimentally, calibration was done based on the concept of the newly established JIS Z 9090, and the practicality of these tool dynamometer machining examples.
This report deals with the truing characteristics of the resin bond CBN wheel, in which the multipoint diamond truer is fed at a constant depth of cut. The total depth of cut of 30-50 μm is required for the initial truing operation of a new wheel. The truing process is classified into four stages. In the first two stages, CBN grains are mainly trued and both grains and bond are ground in the latter two stages, which causes a serious damages on a wheel surface by truing heat. In order to avoid the thermal damages, several passes of the first two stages of truing are necessary for large amount of truing. The setting depth of cut is remarkably different from the actual one due to the elastic deformation of the bond material. As truing proceeds, the new grains below the outermost wheel surface appear and the flank area of cutting edges increase. As a result, the cutting edge spacing becomes close.
This paper describes the dynamic behavior of laser-produced ionizing vapor in laser processing the covalent bond-ceramics. The distribution of laser-ionized vapor is determined by the measurements of electrical potential using newly developed small pin-type electric probes. The density of ionized vapor is highest around a laser beam axis above the workpiece. The distribution and motion of ionized vapor is successfully controlled under the external electric field.
To grind the modern ceramics at high material removal rate, it, is very important to understand the grindability. In this study, a series of alumina ceramics with several grain sizes was ground at constant pressure using diamond grinding wheel. The specific grinding energy which was calculated from a material removal rate and a tangential grinding force was adopted as a criterion of grindability. Conclusions obtained are : (1) The grindability of hipped alumina ceramics can be estimated from both grain size and MOR value. (2) Both brittle fracture and plastic deformation are responsible for the chip generation in grinding of fine-grain alumina ceramics, but the brittle fracture became dominant for coarser-grain material.
In this report investigated is the size and form generation mechanism of very thin workpiece in surface grinding. Main conclusions obtained are as follows; (1) In surface grinding of a very thin workpiece the thermal deformation of chuck can not be neglected because the chuck temperature rises as the grinding heat flowing from workpiece back surface into chuck increases. (2) The size generation mechanism is dominated by the variation of total thermal deformation which is given as the sum of thermal deformations of chuck and workpiece. (3) Lift-up phenomenon takes place at the edge of workpiece width which is departed from the chuck surface by the workpiece curvature after grinding. (4) The concavity of actual workpiece profile is generated by the variation of total thermal deformation with workpiece width taking account of the lift-up phenomenon.
In high precision cylindrical grinding, it is known that the accurate and inexpensive steel balls in place of the cone centers enable to grind workpiece accurately without influences of the misalignments and the geometrical deviations of the center holes. The purpose of this study is to explain the supporting characteristics of these ball centers. In this paper, endurance tests were performed and ball's wear was measured to investigate its effect on the rotational accuracy and the roundness of the workpiece. The obtained main results are as follows : (1) The rotational accuracy and the roundness of the workpiece were kept at high levels during the endurance test of three hours regardless of the ball wear. Therefore, the wear had little effect on the accuracy. (2) The contact points between the ball and the holder gradually shifted to other points, not worn yet. Then the accuracy average effect maintains the rotational accuracy at a high level. (3) Lubrication every quarter hour reduced the ball wear to half. Moreover, the lubrication prevented the ball from release effectively. Consequently, there is no fear for the ball wear in ordinary circumstances.
Parallel leaf spring mechanisms are often used as precision linear motion mechanisms because they are simple and free from friction. Although piezoelectric actuators are optimal ones for driving precision mechanisms, the actuators have only a short working range. The aim of this study is to realize an active parallel leaf spring mechanism and to clarify its characteristics. In the mechanism, leaf springs of bimorph structure are used so that the leaf springs themselves deform actively without using any other driving mechanisms. The active parallel leaf spring has two certain advantages; i.e., high precision achieved by piezoelectric actuators and a longer working range achieved by parallel leaf spring mechanisms. This paper discusses the static and dynamic characteristics of an experimental mechanism theoretically and experimentally. The mechanism in which strain gages are used as a feedback sensor and PI-D elements for a controller, achieved; (1) a control range longer than 0.8mm, and (2) a positioning resolution better than 0.1μm.
Fillet interference in the engagement of profile shifted involute internal gears occurs over a wide range of designing variables. Moreover, disturbance due to fillet interference very often escapes visual detection. Therefore, there is a tendency to overlook careful checking of this phenomenon without due theoretical reasons. To determine the degree of disturbance due to fillet interference in practical use of internal gears, fillet interference was defined in quantitative terms and theoretical formulae were derived. On the basis of the data obtained, a number of fillet interference diagrams were prepared. Detailed testing of the results confirmed that the checking of fillet interference is required except in some special cases. A course to modification of designing variables was suggested.
This paper describes the development of the tracking actuator for high-speed magneto-optical disk drives. The rotating mirror tracking actuator suspended by a single leaf spring is adopted. The actuator is required to have a fine mechanical vibration characteristics, which enables precise control against the high speed rotation of disks for high speed data transfer. However, in this kind of suspension, the higher order mechanical resonances by the spring deformation occurs in relatively low frequencies and reduce the tracking control frequency range. The novel method for suppressing the second order mechanical resonance, in which the drive force is added at the resonance's nodal point, is discussed. And its efficacy is experimentally confirmed. As a result, the higher order mechanical resonances do not appear up to 40 kHz, because the second resonance is successfully suppressed. The damping effect of the viscoelastic layer on the leaf spring is also clarified.
This paper describes the measuring accuracy of the laser speckle interferometer using a double-aperture plate for measuring the in-plane displacement of moving object. In this measuring system, the interference fringes are detected by a CCD linear image sensor, and the in-plane displacement is determined by calculating the correlation coefficient using the interference fringes detected before and after motion. The visibility of interference fringes, the speckle noise and the deformation of laser speckle and interference fringes are discussed experimentally and theoretically on their influence upon the measuring accuracy. From the results obtained, the measuring accuracy is improved by detecting the interference fringes two dimensionally, and the average of measuring error less than 0.15 μm is obtained.
In order to realize feed rate of 20 m/min for cutting operation of medium and large size machine tools, a new high speed and high accuracy feed drive system which has a servo motor and ballscrew combined with a hydraulic actuator has been developed. The previous paper made clear that this system is possible to drive ten times as fast as conventional rate with considerably good accuracy. This paper describes a method for determining optimal PI control parameters of the electric servo motor and PD control parameters of the hydraulic actuator. In order to make the best use of the hydraulic actuator a new function which compare the force of electric servo motor with that of hydraulic actuator is proposed. The experimental results show that the controlling parameters determined by this method reduce motor power and the method is proved to be effective.