Equation of motion of an open loop mechanism is formulated by describing the equilibrium of external force and inertia force around each pair-axis. The topology of an open loop mechanism is represented by a tree-path matrix having the stationary link as its root. An inertia force motor on a link is determined by the extended tensor of inertia in 6 × 6 matrix form, the velocity motor and the acceleration motor of the link. The equation of motion is interpreted in two ways. Firstly, it can be used to calculate the driving torque of each pair axis to realize the specified motion of an open loop mechanism. Secondly, relative angular acceleration at each pair is determined through the equation by velocity motors and external forces of all links. A computer program based on the new equation is developed for three-dimensional dynamic analysis of open loop mechanisms. When the initial state of an open loop mechanism and the external force functions are given, the motion of the mechanism can easily be simulated by numerical integration. Application to some typical motion analysis problems proved the effectiveness of the program.
A new knife edge method is proposed to evaluate the density distribution of laser power converted by a kaleidoscope for CO2 laser processing. The density distribution of the laser power converted by the kaleidoscope and exposed on the calorimeter are calculated first. The power density distribution has a periodical pattern in the radial direction, which forms rings of equal density corresponding to the number of reflections of the laser against the inner surface of the kaleidoscope. The pattern of the power distribution obtained by the knife edge method proposed is in good agreement with the calculated one. It is concluded that the power density distribution measured agrees with the calculated one in quantity by introducing the from error coefficient in calculation to take account of the power loss at the time of reflection.
The purpose of this study is to establish a thermal dressing technique with moving heat source for resinoid bond wheel, in which heat resistance of bonding material is markedly lower than that of vitrified bond. In this paper, a single pulse of CW : YAG laser introduced as a heat source is irradiated on resinoid bond abrasive stick to make clear a fundamental phenomenon of laser dressing, analyzing transformation, profile of resinoid surface, stiffness of grain mounting and so on. Main conclusions obtained in this paper are as follows : (1) Transformation of resinoid bond, releasing abrasive grain and vaporization of bonding material take place with laser irradiation. (2) The depth and diameter of heat affected structure increases with increasing power density and irradiating time of a laser beam. (3) A stiffness of grain mounting decreases as a distance to an abrasive grain from a beam center decreases in heat affected surface.
In the explosive forming method using only a blasting cap as the explosion source, by changing the distance between the blasting cap and a blank, the amount of deformation of the blank is controlled.Therefore, it is important for controlling the amount of deformation to forecast how much proportion of the explosion heat of a blasting cap is converted to the deformation energy. In this report, the strain energy required for the deformation of a blank is calculated, and with its ratio to the explosion heat of a blasting cap, the energy efficiency of the blasting cap is to be determined. In the case of using a die with the cavity radius of 36mm and the shoulder radius of 3mm, and carrying out the free forming of a brass sheet of 0.8mm thickness, the following results were obtained. N amely when the distance between a blank and a blasting cap was close, and it was assumed that the strain energy of the blank is 0.79 kJ, and the explosion heat of the blasting cap is 0.3 kJ, the energy efficiency was 26%.When the distance was 1200mm, the strain energy was 0.16 kJ, the strain energy efficiency was 5.5%.
This report deals with the precision truing process of metal bond diamond wheels for truing up cutting edges. This truing process consists of three steps. In the first step, the runout of the wheel mounted on a spindle is reduced by machining both diamond grains and the bond of the grinding wheel with a truing diamond wheel. In the second step, the bond is removed using the electrolytic dressing to a depth of 1/3-1/4 the average grain size of the grinding wheel. In the last step, the cutting edges of the grinding wheel are lapped with a cast iron plate for truing up. After performing this truing process on a # 400 diamond wheel, the runout of the mounted wheel was reduced to within 0.3 μm, and the accumulative cutting edges below 0.5 μm depth in the outmost wheel surface were increased more than six times those after conventional truing. Therefore, the bottom of groove in one pass grinding on ZrO2 with a # 400 diamond wheel is machined in ductile mode, and the surface roughness is extremely improved (2.1 μmRmax→ 0.2 μmRmax).
The present paper deals with a ductile mode ultraprecision grinding equipment, which is developed for industrially realizing crack free grinding of semiconductor materials with high shape accuracy. This equipment is composed of ultraprecision systems such as force-operated linear actuator, composite bearing guideway mechanism, stationary spindle structure, 10 nm resolution feedback NC control and so on. By these systems, inching resolution of the grinding wheel head reached 10 nm, and the loop stiffness between grinding axis and rotary-table is 150 N/μm. The thickness of dislocation layer remained on the ground silicon wafer is about 0.5 μm. It is confirmed that there are no cracks remaining under the ground surface from SAM (Scanning Acoustic Microscope) observations. On the other hand, in case of conventional precision grinding machine, many cracks were observed along grinding marks. The LTV (Local Thickness Variation) which describes local flatness for all cells is under 0.4 μm. The TTV (Total Thickness Variation) which describes global flatness is 0.55 μm.
This paper describes the interface adhesion behavior between cutting tool and workpiece when the pure iron and low-carbon resulfurized free-machining steel were plunge machined. Adhering force between tool and pure iron increases in the order of ZrO2, TiN, SiAlON, TiC, HfO2, Al2O3, WC, Fe3C, ZrN and La2O3. Nearly linear relation is observed between adhering force and contact angle. On the other hand, adhering force between tool and sulfide inclusions decreases in the order of ZrO2, TiN, ZrN, Al2O3, TiC, HfO2, WC and Fe3C. In this case, the adhering force seems to be a linear function of sulfide formation free energy-Δ Gf. Adhesion of pure iron and sulfide inclusions to the tools may caused by chemical interaction.
Causes of flank wear are examined first. As a result of examination, it is realized that the elongation of duration untill cBN particles fall off from ceramics binder is effective to improve the wear resistance. By way of extending the duration time, TiN film is coated on surface of cBN particles (size 1-3 μm) by thermal CVD, and cBN tools consisting of TiN coated cBN particles and ceramics binder are fabricated by high pressure sintering process. Using the cBN tools, cutting test of hardened steel is carried out. Main findings are as follows ; (1) The pores appeared in the layer of cBN particles and ceramics binder in cBN compacts made of TiN coated cBN particles show a decrease of number by 1/10, and, its critical stress intensity factor (KIC) shows an increase of 40%. (2) Comparing the cBN tools made of TiN coated cBN particles with no coated one, it is realized that the wear resistance shows an increase of its value by 2 times, and tool fracture resistance is also improved.
In this paper, an estimation method of nonlinearities in mechanical structures is proposed with impulsive response methods, which are conventionally applied to the linear structures. Their efficiency is verified experimentally on the model structures with nonlinear spring characteristics, which are a bearing supported shaft and a bolted beam. The following results are obtained. In the time domain, the relationship between the average amplitude (AA) and the equivalent logarithmic decrement (ELD) as well as the relationship between AA and the equivalent natural frequency (ENF) can show qualitatively the existence, the intensity and the type of nonlinearity. In the frequency domain, the transfer functions such as Bode plots, Nyquist loci and their dependencies on exciting forces can show clearly the existence of nonlinearity in the structures. For instances, the structures have the characteristics of hardening springs, if ELD increases and ENF decreases as AA becomes smaller and the center of Nyquist loci rotates to the counter clockwise. And if these behaviour has opposite tendencies, the structures have the characteristics of softening springs. The experimental results show good agreements with the results from the theoretically proposed methods.
Using molecular dynamics (MD) computer simulation, an attempt is made to analyze and understand the chip removal process in micro metal cutting under sub-nanometric uncut chip thickness. Microcutting experiments on copper workpiece are also carried out under the uncut chip thickness down to 1 nm. Comparison shows a fairly reasonable correlation between the chip morphologies and the size effect in the cutting force and specific energy obtained from both MD simulation and microcutting experiments. The results suggest that MD simulation can be a useful tool for the analysis of chip and surface generation process in microcutting. The chip formation process is well understood as the successive generation of dislocations on tool-work interface and their passing through the shear zone to the free surface.
This paper describes an automated pattern inspection system for circuit patterns of multilayer thin-film on a ceramic substrate. Thin-film layers, usually made of resin and metal circuit patterns, are alternately formed on a ceramic substrate. To inspect all those thin-film layers inline visual inspection is used. This inspection involves detecting defects existing in a surface layer just after the layer is formed. Surface circuit patterns must be optically differentiated from patterns on inner layers. For this purpose, bright and dark-field combined illumination is used and the wavelengh of reflected light to be detected is selected in a specific range. Illumination is achieved by a 4-fold ring-light-guide structure and bright-field illumination. The “Local Pattern Comparison Method” is used for defect detection in which a detected binary image is locally compared with a reference image. This method can be implemented by means of an image processing hardware system using a pipelined architecture for real-time operation. An automated pattern inspection system was constructed with the above mentioned pattern detection and defect detection method. According to the evaluation results, the inspection system can reliably detect defects as small as 10 μm.
Generally, a diamond circular saw blade generates the vibration and the noise when it is rotating at high speed. Under the specific condition, the noise called “whistling noise” which has sound pressure level of over 110 dB occurs. This whistling noise causes working environmental pollution. In this paper, the effects of the number of segments, the slits, and the natural vibration of the blade on the generation of whistling noise were investigated experimentally. The main results obtained are as follows : (1) The generation of whistling noise is influenced by the rotational speed of the blade. (2) The rotational speed generating the whistling noise increases with an increase of number of segments. (3) The generation of the whistling noise is concerned with the natural vibration and the peripheral air flow of the blade due to the slits.
The present report is concerned with the results of shaking table tests of L-shaped piping supported by the semiactive damper which the authors have developed for piping systems. The damper is composed of a ball screw, a disk brake and piezoelectric actuators. The brake force is controlled corresponding to seismic responses of the piping or input accelerations. L-shaped piping of length 3 m × 3 m and outer diameter 60.5 mm is used as a piping model in shaking table tests. Both ends of the L-shaped piping are rigidly attached to the shaking table through supporting walls. The semiactive damper is attached between the bent section of the piping and the shaking table. Input accelerations used here are EL Centro (1940) NS and Akita (1983) NS normarized to be 2 m/s2 at the maximum acceleration. The results may be summarized as follows : (1) The deflection of the L-shaped piping can be reduced successfully by the semiactive damper. (2) The semiactive damper has the effect of vibration suppression even by simple control method such as on-off control or proportional control. (3) The results of shaking table tests of the piping agree approximately with the calculated results.
A new method to calibrate precision meters for metrology is proposed. In the method two meters including sensors and amplifiers are used to compare their outputs with each other and any accurate meter for the reference of calibration is not necessary. The calibration system is constructed by two meters A and B to be calibrated, a kind of lever to give displacement and precision stages positioning the sensors axially. Calibrating with this system, the linearity error of calibration line is determined within an uncertainty limit, which is given by resolution power of the sensors, electric noise and thermal disturbance of circumstance. As a trial experiments, capacitance type displacement meters (micro sense) have been calibrated. The output of the meters with 50 μm range is determined within an uncertainty of about 10 nm. The proposed self-calibration method can determine the most certain calibration curve which can be able to be obtained in the circumstance of the experiment.
In this paper, first, the design method of the discrete-time position control system of a body supported elastically is showed. In the design of the discrete-time position control system, the pulse transfer function of the body supported elastically and driven by a linear DC motor is derived by the z-transform, and the discrete-time control voltage of the linear DC motor is obtained by applying the inverse dynamics or the neuro-adaptive control in consideration of the delay time due to the computation time of the control digital computer. Then, from the experimental results, the usefulness of the present design method of the discrete-time position control system is confirmed, and the control performance of both control methods in regard to disturbance is compared. Furthermore, from the numerical simulation results, the effects of the sampling time on the control performance of the neuro-adaptive control is demonstrated.
Analysis of thermal deformation on an aluminum laminated plate fixed to a flexible printed circuit (FPC) by adhesive leads to the development of a head-arm for a magnetic disk storage system. This work examines the establishment of a simple method for calculating thermal deformation. The efficacy of the composite beam method is investigated by comparing a measurement made by holographic interferometry and two calculations made by a finite element method, with the composite beam method. This research confirms the reliability of the calculation method using the equivalent characteristics of a simplified FPC. When the shearing deformation of an adhesive is neglected, the thermal deformation of an aluminum laminated plate can be easily calculated by using the composite beam method. When the Young's modulus of the FPC is small and the adhesive is thick, thermal deformation cannot be calculated using the composite beam method because of shearing deformation of the adhesive. It is possible to simplify the complicated shape of an FPC using the above two calculation methods.
This research proposes a 7 D. O. F. crane with three wires for automatic heavy part handling. Since the crane suspends its object with three wires, it can reduce all the vibration modes of its suspended object. This paper proposes a method of the vibration control of the suspended object. Though the dynamic model of the crane control system is very complicated, three decoupled sub-systems are obtained after the linearization of the dynamic equations at an equilibrium point. Three optimal regulators are designed respectively and installed in the crane to reduce the residual vibrations in positioning. The experimental results using a prototype crane prove that the crane is efficient in handling heavy parts.
This paper describes a mask-to-wafer fine gap setting method for an X-ray stepper. A capacitance micrometer on the wafer chuck and those on the mask chuck are used in this method. The mask and wafer surfaces are positioned parallel to the travel plane of the wafer x-y stage so that the gap does not vary with the step and repeat motion of the wafer stage. Therefore, gap setting is required only once for each wafer, and the throughput becomes better. This method has the following two additional merits. A complex gap measurement optics is not required and the setting value of the gap is variable. The gap setting error caused by mask unflatness, wafer unflatness and travel error of the wafer x-y stage was analyzed. Experiments were carried out using mask and wafer stages both with 6-axes. A gap setting accuracy better than ±1.5 μm at the exposure positions of 5 wafers has been achieved for 30 μm and 20 μm gaps.