This paper describes a method of generation of the free-from surface by the boundary integral equation using the polyharmonic function. This method requires boundary geometry of the free-from surface and the lines on the free-from surface, which are contour lines for example. The height of points on the free-from surface is calculated, after solving the discretized boundary integral equation. Several elements and their shapes, which are useful in this method, are shown. In order to investigate the efficiency of this method, this method is applied to the CAD for dies.
NC machining of mechanical parts having free-form curve shapes such as cam's profile curves is usually done by using linear and circular interpolation. The problem with this approach, however, is that a large number of machining data is needed. Moreover, the tangent and curvature at the interpolated points are not continuous. In this report a practical method for clothoidal interpolation is discussed. Linear and clothoidal interpolation are compared each other in three methods. The first method divides the parameter angle equally with maximum allowable error. The second method divides the length of the curve equally with maximum allowable error. The last method selects every angle or length with equal allowable error. The results show that clothoidal interpolation requires less data than linear and circular interpolation to satisfy given tolerance between interpolation points.
This paper describes a novel three dimensional measuring system using gray code projection. The method of this system is based on the principle of time sequential space encoding. Measurement space is encoded to 256 spaces by four gray level patterns, and it takes about 0.6 second that we get this encoded image. These patterns are projected by liquid crystal color projector, and are taken by CCD camera. When measurement area is 120mm×100mm, measurement accuracy of this system is 1mm, and the standard deviation is 0.4mm in the horizontal crosssection, 0.24mm in the vertical cross-section.
This paper presents a method to control feed velocity of precision feed devices driven by means of walking drive, and ultraprecision positioning is realized by a laser feedback controller developed. It is confirmed that the feed velocity can be controlled easily and simply by the method presented. Major results obtained are as follows ; (1) Positioning accuracy of 5 nm is realized, because of no friction against the feed motion. (2) Smooth continuous path control is realized despite short strokes of the piezoelectric actuators. (3) High stiffness of about 40 N/μm is realized in the feed direction.
ISO TC10/SC5-1986 TR has proposed some verification methods of the related features such as positional tolerance, parallelism and coaxiality of cylindrical parts. As most of these proposed methods are performed by using some simple measuring tools, the reliability of verified values may be too low for high precision parts. In this paper, the authors develop the technique to verify the accuracy of related features for eccentric crank shaft by software. In this technique, the position and the orientation of eccentric cylinder axis of crank shaft are obtained by processing the form data of cylinders which are measured by the instrument for measurement of radius variation from rotating table center without the operation of centering.
In the geometrical tolerance standards, related features are defined by the spatial relationship between datums and toleranced features. This relationship, therefore, must be taken into consideration for inspecting workpieces, which are designated on their drawings as related features. In this paper, an evaluation method for related features with geometrical constraints in coordinate metrology has been proposed. Geometrical constraints in position and orientation, which are formulated as linear equations, has been used in this method, which is based on the small displacement screw model. The results obtained by the proposed algorithm have also been analyzed in comparison with existing related standards. Computer simulation has been performed on some cases to verify the results and validity of the method has been confirmed.
Increasing integrated circuit packaging density calls for silicon wafers with smaller surface micro-roughness. In advanced device fabrication processes, rinse or ion implantation steps can create unacceptable roughness in oxide films or silicon base materials. Since the device element is of micron size, there is no method to confine processing to such a small area. In this study, a new method to perform processing within a micron sized area has been achieved using an atomic force microscope. Thus, the atomic force microscope is not only used as measuring equipment, but also as processing equipment. When processed using the atomic force microscope, surface roughness is smoothed to the atomic scale. This can not be achieved using any conventional methods. The new smoothing process discussed in this paper, is done in an alkaline water solution. The actual materials are charged to improve the good removing ratio.
Laser repairing of surface defects of steel billet was studied. Four core technologies necessary for developing the new method were extracted and developed. First, a new optical system focusing a laser beam to line-shape was developed, in order to melt off surface defects. Secondly, laser melting method with O2-gas blow was developed for removing molten parts of the surface not to remain bad effects on the billet quality. Thirdly, it was made possible by laser heating process simulation model and experiments, to predict the required laser power for repairing both cold and hot billet. Fourthly, a flying optical system, which focuses a laser beam at each position of surface defects of the fast running steel billet, was discussed. It can also decrease the required laser power by running along the same direction of the billet. Thus, core technologies have been prepared. So, the laser repairing method for steel billet will be realized as a total system.
The purpose of this study is to develop the basic theories and techniques for a plant inspection and diagnosis robot. The robot dealt with in this study will works in the large scale unmanned plant or a place with dangerous equipment. It has the ability widely to monitor the condition of plant machinery with only a few sensors, and quickly to discrimimate machine failures, in order to guarantee both the quality and quantity of production against accident. In this paper, the conceptual design and the method of failure detection by sound information for a plant inspection and diagnosis robot are discussed, including following contents : (1) the basic function and structure of the plant inspection and diagnosis robot, (2) the calculation method of symptom parameters from sound signal for detection and diagnosis of machine failures, (3) the method of making membership functions of the symptom parameters by possibility measure theory, (4) the method of failure discrimination by the membership functions, (5) examples of practical inspection and diagnosis.
In this paper, authors discuss about development of a wireless communication system for a distributed autonomous robotic system, which is composed of various types of multiple agents. In order to achieve cooperative behavior among multiple agents including mobile robots, it is required to enable performance of communication with flexibility, reliability and interoperability. Based on these requirements, a wireless communication system based on the Carrier Sense Multiple Access (CSMA) have been designed and developed by using wireless MODEM's. A hierarchical architecture is adopted for consistency and for interoperability. This communication system is applied to a prototype system consisting of actual mobile robots and a workstation. In this paper, it is shown experimental results of inter-communication by using the prototype system. Authors have proved above performance required in the wireless communication system.
A new assembly method using guide-frames is described for easy construction of compact and practical free-space optical modules. Basic performances of this method are examined by assembling a two-dimensional optical fiber collimator, which is used to free-space optical telecommunications systems. Also, the method is applied to assemble a digital discrete correlator (DDC), which is a fundamental part of freespace optical computing systems. It is shown that a multistage optical system can be constructed simply by stacking the several optical functional blocks, and these compact modules do not need an optical bench, and they are one tenth of conventional optical system volume. It is demonstrated by experiments that our proposed assembly method can be utilized for these optical modules.
A new method of numerically controlled ultra fine polishing for brittle material is proposed. In this method, the offset of the polisher to the designed profile is controlled to be constant in non-contact, and the feed rate of polisher is fixed instead of polishing load. In this report, the surface polishing characteristics of this method and the influence of the viscosity of polishing compound are examined theoretically and experimentally. The following results are obtained : (1) When the clearance between the polisher and the work surface exceeds the definite value, the machining action does not occur. (2) The flow rate of polishing compound at the gap between the polisher and the work surface, and the stock removal rate are independent of the viscosity of polishing compound. (3) Observations of surface textures with roughness tester and AFM indicate that the surface roughness of polished surface is improved with the increase of the viscosity of polishing compound.
The drive mechanism of perpendicular guideway mechanism means that out of the two actions, load (slider's own weight and frictional force) driving action and positioning command issuing action. The former action is released and only the latter is retained. Therefore, it is necessary to increase stiffness of the drive mechanism. This paper proposed new drive mechanism which reduces load to be applied to the drive mechanism and increase stiffness equivalently. The new drive mechanism is called load compensated drive mechanism. This drive mechanism proposed here is introduced as a means of overcoming the resulting stick slip phenomena and lost motion to improve feed resolution. The experimental results on the composite bearing guideway of the proposed system achieved a positioning accuracy 0.153 ± 0.027 μm/step. The details of the composite bearing guideway mechanism was discussed in the first and second papers. The present paper reports positioning characteristics of the load compensated drive mechanism from experimental and analytical (phase plane analysis and computer simulation) results.
Mn-Zn (Manganese-Zinc) ferrite polycrystals have been widely used as a core material of magnetic heads in video cassette recorders or floppy disk drives of personal computers. In this research, slot grinding was performed to investigate the chipping generation mechanism at slot edge of Mn-Zn ferrite polycrystal with metal bonded diamond wheels. A high precision slicing machine with an air spindle of low friction and low thermal expansion was used. After grinding, the chippings at a slot edge was measured by means of a form tracer with a knife edge tip, and analyzed with a newly developed measurement method using a personal computer under various grinding conditions. On the other hand, by means of SEM observation, a material removal mechanism at the edge of Mn-Zn ferrite was investigated. The results are follows. Pre-process, such as lapping, before grinding can reduce chipping size. Most of chipping is generated by transgranular fracture. As chipping size depends on the removal per grain; qw=α·μ2 (Vw/Vs), a decrease in removal qw, chipping size after slot grinding could be reduced.
This paper deals with a trial of gear grinding using a vitrified-bonded CBN wheel of screw shape. Compared with an electroplated CBN wheel, a vitrified-bonded CBN wheel is more suitable for obtaining gears of high accuracy because it permits the profile to correct and refine the cutting edge without removing the wheel from a spindle head using an onmachine type truing device. Then the authors designed this truing device and carried out some grinding experiments using a metal-bonded diamond wheel of V-shape for a truing cutter, and proposed a dressing process using gear-shaped GC wheel after truing. This dressing process has an effect to reduce the grinding force without impairing gear accuracy. The grinding results showed small profile errors and pitch errors in case of grinding speed at 7 000 min-1 with double-threads wheel whose diameter was 200 mm, and it was confirmed that we can use a vitrified-bonded CBN wheel of screw shape for gear grinding.
Sintered diamond cutting tool has been widely used for cutting Al-Si alloys. Cutting performance of sintered polycrystalline diamond (PCD) tool for cutting Al-16% Si alloy was studied. In this study, PCD tools of various diamond grain sizes were prepared to find out the most suitable grain size. A continuous cutting test was applied for evaluating wear characteristics. An interrupted cutting test was applied for chipping characteristics. Chipping width decreases with decreasing grain size of diamond. Wear performance has the most suitable grain size at 4-8 μm. Relation between chipping width and the strength of PCD has linearity. Wear property relates to the hardness of PCD and fracture toughness.