In machining internal surface of the work which is tightly clamped by machine vice, there is possibility of occurrence of significant machining error due to elastic deformation of the work by clamp force. The elastic deformation can be analyzed by the use of FEM. However, operation of FEM program needs special skill and experience. Then, the analytical simulator has been developed for personal computer, which can almost automatically operate FEM program to predict the machining error due to elastic deformation of the clamped work. The simulator is the computer analysis system that FEM program and CAD program for various purposes are joined with the originally developed interface program. Drawing of plan of the work, meshing and necessary data generation for FEM analysis are done by CAD. The interface program generates the operation commands for FEM program according to CAD output data. FEM program is automatically operated by the commands. Since operation of this simulation system is very simple, for anyone who is inexperienced in FEM analysis this system is available too.
A vertical X-ray stepper for SOR lithography has been developed. The stepper exposes wafers in a normal atmosphere to vertically-scanned SOR with continuous alignment control during exposure. The key devices of the stepper are a vertical X-Y stage and an opticalheterodyne alignment system. The X-Y stage uses air-lubricated components, including air bearing lead screws, linear sliders and radial/thrust bearings. The optical-heterodyne alignment system detects the displacement between the mask and wafer gratings with precision of 8.3 nm. Several exposure experiments proved that the alignment capability is better than ± 0.1μm for a 3σ-value.
The handling of a heavy work is a dangerous task. A crane is one of the suitable mechanisms to handle the heavy work, but it makes the suspended work vibration. This paper proposes a heavy work handling system which consists of a crane and a robot. A flexible arm is installed at the tip of the robot in order to avoid large reaction force when the robot grasps the swinging work. The mechanism is modelled as two springs and a mass. Based on this model, a cooperative control system between the crane and the robot is designed for positioning the work. The robot is position-controlled as a master and the crane is velocity-controlled as a follower. To reduce the vibration of the work, the crane is controlled through the feedback signals of both the deflection of the flexible arm and the velocity of the crane. Additionally a feedforward signal from the robot controller is used. Experimental apparatus is made with 3.9 kg weight. The performance of the system is studied with its simulation. Experimental results prove that the system is very efficient in handling heavy works.
The purpose of this work is to improve both reliability and execution speed of the CAD/CAM system. The underlying technique for this enhancement of performance is parallel processing, applied to the offset surface and tool path generation. The developed system is constructed with a personal computer and 15 Transputer boards. The tasks of the Transputers structured in hierarchy are as follows : (1) The first level has a master Tranputer that performs the management of the data. (2) The main task of the second level is the calculation of the cross section curve of the required surface. (3) The offset surface generation is carried out by the third level. Another task to be executed by these Transputers is the tool path generation. The software algorithm called “the Inverse Offset Method” has been coded in Occam. Simulated results show that parallel processing offers a reliable solution to the shortcomings of the Inverse Offset Method, and the development of new CNC controller is feasible, which can accept geometrical data and generate tool path in real time.
Analyses of the first report suggested that the unique phenomena in very low speed grinding process might be generated by the “built-up edges” in grinding machining. Explanation of the growth mechanism on the unique phenomena has been made clear in this report. Main conclusions are as follows: (1) In very low speed range of the unique phenomena the variations of abrasive grain temperature almost agree with the variations of cutting point temperature that the built-up edges are generating in the cutting process. (2) Micro-structure of the adhered material to grinding wheel surface shows the similar structure of the built-up edges in the cutting process. (3) The adhered material can generate the grinding chips after considering the comparison of hardness between the adhered material and grinding chips. The facts of above conclusions become clear that the “built-up edges” have been formed in very low speed grinding process.
This paper deals with exit burrs produced in drilling. The development of yielded, deformed and strain-hardened area is investigated respectively by Finite Element Method(FEM), Grid Method(GM) and Hardness Distribution Measurement(HDM) to clarify the burr formation mechanism. In FEM, the drill exit part of workpiece is divided into 198 triangle elements and 119 nodes. For GM and HDM, aluminum alloy(A6030 in JIS) plates of 10mm thickness are drilled under various cutting conditions with drills of 8mm diameter and various helix angles. And also the measurement of cutting forces is done at the same time. The plastic deformation of workpiece starts at the drill point part, and then occurs mainly at the outer corner part. Both plastic deformation and burr become small as the helix angle increases. Burr shapes are divided mainly into two types. One is a small even burr with or without a conical hat chip. The other is a large burr shaped like a petal. The difference of the two burrs is caused by the formation of a conical hat chip.
Tool edge roundness and relief angle effects have been investigated on cutting force, depth of reluctant uncut, depth of deformed part and machined surface texture. Larger edge roundness tool offered greater depth of deformed part and depth of reluctant uncut. Relief angle values could not provide significant effects on tangential force, depth of deformed part and surface roughness. However, smaller relief angle allowed normal force and depth of reluctant uncut larger. Regardless of relief angle value tangential and normal cutting force were markedly dependent on depth of deformed part and reluctant uncut respectively.
The purpose of this paper is to acquire the knowledge of a skilled machinist in respect to polishing operations of injection mold cavities, in order to develop a high performance polishing machine. Polishing experiments with different kinds of polishing tools are carried out not only by a skilled machinist's handwork, but also by mechanical method. The polishing properties of a skilled machinist in respect to surface roughness, stock removal and scratch are obtained and analyzed quantitatively. The surface roughness decreases exponentially with the increase of polishing times. The surface roughness (Ra) depends on the following threeactors : roughness before polishing (Ro), final surface roughness (Re) and exponential coefficient (a). The stock removal curve can be represented approximately by two lines and the polishing times corresponding to the intersection of the two lines coincide with the critical polishing times in which the surface becomes better by a degree of 90%. Differences of surface roughnesses between hand polishing and mechanical polishing are small being only 10%. However, the rate of stock removal to polishing times in hand polishing is large being about twice that in mechanical polishing, and the rate of scratch to roughness in hand polishing is kept constant with 4 for different kinds of tools and smaller than that in mechanical polishing.
Using the reactions between diamond and metal, diamond film has been polished by hot metal with low applied pressures and spinning speeds. In this report, the polishing mechanism of diamond is discussed experimentally. The polishing rates are in the same order as the diffusion coefficients of carbon in metal. Polishing performed in vacuum or hydrogen gas atmosphere advances much more quickly than in inert gas atmospheres. Although in a hydrogen gas atmosphere, diffused carbon react with hydrogen to form methane gas, and in vacuum, the diamond film is etched by residual oxygen gas, the polishing rates are not affected apparently. The dominant reaction between diamond and metal is thought to be the diffusion of carbon into metal.
A laser patterning was achieved for integrated-type amorphous silicon (a-Si) solar cell submodules with large area, for example a size of 40 cm × 120 cm. For further improvement in the selectivity for YAG laser patterning of metal electrode of integrated-type a-Si solar cell submodules, a new patterning technique has been developed based on the ArF excimer laserinduced patterning. This paper describes some experiments with laser patterning of metal film with optical-induced etching. In order to achieve good selective patterning for Al electrode, Laser Pre-etched Photochemical Etching (LPPE) method has been developed. First, the surface of Al is denatured in BCl3 atmosphere by a convergent beam of ArF excimer laser. Next, a non-convergent beam is used to etch only the denatured Al portion. It decreases the heat affecting the a-Si and improves selectivity. It was confirmed that excimer laser-induced patterning was very useful for patterning of metal electrode in a-Si solar cells.
This report deals with both microscopic and macroscopic behaviors of the CBN wheel surface during the cylindrical traverse grinding, which are closely related to the grinding performance. The microscopic behaviors are investigated by observing the cutting edges, and by measuring the cutting edge spacing and the depth of chip pocket with a newly developed equipment, the computer handling system of wheel surface. In the circumferencial wheel surface of starting side, the bond is removed rapidly and the wear, the fracture and falling-off of cutting edges occur within the initial stage of grinding, so that the depth of chip pocket and the cutting edge spacing increase rapidly to the certain value, respectively, corresponding to the grinding conditions, that is, the larger depth of chip pocket than that obtained with the usual method is required in this area. These phenomena are observed in the advanced stage of grinding as the position of wheel surface is apart from the starting side, and the large amount of stock removal is necessary at the opposite side of the wheel. The wheel shape during grinding changes in company with the behavior of cutting edges.
The purpose of this research is to realize precise straight motion. The straight motion system used in the paper has an ability to control five degrees of freedom of a moving table; vertical and horizontal positions, and roll, pitch and yaw angles. For the purpose, two references are introduced; motion reference and absolute reference. Table motions are controlled relatively to the motion reference. A solid master is used for the motion reference because of its stability against changes of environment. A geometrical error of the motion reference causes motion errors of the table. To compensate these errors, motion errors relative to the absolute reference are measured. The paper proposes the liquid surface for the absolute reference. The liquid surface is used only to measure motion errors caused by the geometrical error because the liquid surface is not robust enough. After the compensation, straight motion accuracies of 0.2μm in vertical position, 0.1arc sec in roll angle and 0.3arc sec in pitch angle were achieved.
This research aims at developing a large power, ultra precision positioning system by using giant magnetostriction materials. The giant magnetostriction materials have the features that large power and large displacement can be obtained as compared with electrostriction PZT, but on the other hand, the control of the thermal deformation due to the generation of Joule's heat became a problem. In this study, in order to realize the ultra precision positioning with nm errors, a temperature controller within 10 m°C was developed, and an ultra precision positioning device equipped with it was manufactured for trial. The results obtained were as follows. (1) By adding the device which can control temperature to the variation within 10 m°C to a giant precision positioning system, the system which can do the positioning with nm errors was able to be developed. (2) As compared with the positioning by electrostriction PZT, by the giant magnetostriction having the features of large power and large displacement, ultra precision positioning became feasible. (3) The giant magnetostriction positioning system, in which the hysteresis is small in high load condition and which has the displacement efficiency of about 90%, was able to be developed.
This paper deals with the study on a new high speed and high accuracy feed drive system for medium and large size machine tools. In order to realize feed rate of 20 m/min for cutting operation which is ten times as fast as conventional rate, a hydraulic actuator was combined with the conventional electric servo motor and ball screw, which means the independence of a function of accurate positioning by electric servo motor and ball screw system and that of acceleration and deceleration by hydraulic actuator system. After confirmation of the performance by theoretical analysis of the system a prototype model was built and tested. Contouring accuracy measurement system using a laser interferometer was also incorporated. Experimental results show that radius reduction amount of circular interpolation of radius 150 mm was 230 μm at feed rate 20 m/min and 7 μm at 5 m/min. The experimental results prove effectiveness of the proposed system.
The present paper deals with a method of estimating damping ratios and natural frequencies continuously in process of a cutting operation, which represent an instantaneous state of a cutting vibration system. A new algorithm of estimating plural sets of damping ratios and natural frequencies directly evading a time-consuming factorization is proposed, which uses plural time series models interconnected and corresponding adaptive filters. The function, accuracy and the follow-up ability to the change of the vibration system are confirmed through a simulation by using preknown time series data. In order to verify the applicability of the proposed method to practical cutting data, acceleration signals detected at a tool shank during turning tapered SS 41 workpieces are analyzed. As results of the analyses, changes of damping ratios and natural frequencies related to chatter vibrations are clearly observed and an effectiveness of the method is confirmed.
A method to identify a mathematical model which represents the relationship between thermal displacement and temperature on a machine for compensation of the displacement has been proposed. The model uses moving averaged time series data of temperatures to reduce the measuring points and to keep the good agreement between actual and estimated displacement even for a wide range conditions. The parameters in this model are determined by data of the displacement and the temperatures obtained from six operating conditions of a machine. The new mathematical model can estimate that thermal displacement over 50μm within 2μm accuracy by 14 points of temperature measured.
A one-axis stage mechanism, driven by an AC linear motor and guided by a rolling ball guide, has been constructed. Non-contact drive and position-sensing are adopted. The dynamic characteristics of the stage are different in different displacement regions. Two different controls are designed for coarse and fine positioning by using different dynamic characteristics. A coarse positioning with 100 nm resolution, 200 mm/s maximum velocity and 250 mm stroke, and a fine positioning with better than 1 nm resolution without backlash are achieved. The switching from the coarse positioning to the fine positioning is studied.