A machine that can detect automatically defects such as flaws, notches and scratches on edges or planar and cylindrical surfaces of vanes has been developed. Most flaws on the edge can be detected using the technique of "oblique illumination and normal detection", but the flaws inclined largely toward the surface of machine parts cannot be detected by the above-mentioned technique. In this paper, we clarify that such flaws with large inclination on the edge, and notches and scratches, on the surface can be detected using the technique of illumination and detection normal to the surfaces of vanes. Defect candidates are recognized by binarizing the detected image and the maximum lengths "l" and the areas "a" are counted. "a0" is calculated in order to eliminate a sampling error which is generated in the binarizing process, where a0is 1.3l. Experimental results reveal that the defect candidates with areas larger than max(20, a0) pixels are true defects.
This paper describes the possibility of sensing for machining, using the sound that occurs under paperboard die cutting, which is commonly used for making various paper packages. Among the actual production lines, it is important to estimate the wear of die tools. And any kind of automatic technique for detecting cutting condition is required for increasing productivity and reducing operator's task. In this study, the sound radiated in the cutting process was measured by varying several machining conditions on the test machine, and analyzed. The following results were obtained: The sound seems to be caused by impulsive strike between a blade tip and a counter plate; The repeatability of sound waveform is very good in the same machining condition; Obvious feature is not revealed in the sound spectrum for distinguishing each condition; On the other hand, a sound pressure level (SPL) denotes obvious difference among each condition; The radiated sound energy is almost in proportion to the elastic energy stored in the machine just before completion of cutting. Hence, the SPL would become a good index to denote the wear of blade tip, the occurrence of harmful thread dross, etc.
At ductile-mode grinding, the material is removed within a plastic region so that no crack remains on the corresponding surface after machining. By effectively using this mechanism, fixed abrasive process is seen as a promising solution to replace the lapping and polishing processes in manufacturing of large scale Si wafer. In principle, however, there is still plastic strains developed. This fact makes it very difficult to completely remove the damaged subsurface layer by fixed abrasives. To achieve a perfectly damage-free surface, this research has proposed a new chemo-mechanical-grinding (CMG) process by adding chemical effect into the grinding process. First described in this paper are the experimental results showing the feasibilities of the CMG process in reducing subsurface damage. Based on the preliminary test results, CMG wheels which contain chemically active abrasives and additives have been developed and characterized with a wide range of pH from acidity to alkalinity accordingly. The CMG has been mainly evaluated by the grinding performance on bear Si wafers, comparing to grinding with diamond wheels. From the technical and economical points of view, CMG is also highly expected to perform planarization function instead of chemical mechanical polishing (CMP) process. The primary tests of CMG have been done on shallow trench isolation (STI) patterned wafer to investigate the pattern dependency.
ITO film, which is a kind of transparent conductive film, has been used for LCD, PDP and so on. This film is mostly removed by wet etching method. However, this method needs many chemicals, processes and large-size equipments. On the other hand, laser beam processing can drastically reduces the number of process by achieving the dry process without chemicals. Therefore, selective removal of ITO film of 85nm in thickness on glass substrate by LD-pumped Q-switch SHG YAG laser is experimentally investigated. Electrical insulation across machined groove was successful. Better groove shape can be obtained by accurate control of defocused distance and feed rate under a constant average power. Using SHG YAG laser makes it possible to remove only ITO film without any damage on glass material as substrate, since SHG YAG laser of 532nm in wavelength is easy to transmit the glass material. When laser beam is irradiated from ITO film to glass, a non-removed portion of ITO film remains at the bottom of groove under long defocused distance condition. On the other hand, the non-removed portion can be prevented from remaining by backside irradiation, in which laser beam is irradiated to ITO film through glass material. Because absorption of laser beam occurs at the boundary part between ITO film and glass material.
Spin angle controlled ball lapping method developed recently, is to have an excellent performance to lap the ball, in which V-groove lapping plates are separated into two parts and three plates are able to rotate independently. Present paper focuses on polishing characteristics of a steel ball using vesicant polyurethane pad. Experiments are conducted using an aluminum oxide grain ranging from 5.5 to 0.3 μ m in size. It is found that the surface roughness of steel ball polished by vesicant polyurethane pad is smaller than that of the cast iron lap. Experiments show that the grain size degradation is very effective for decreasing the surface roughness of ball. It describes that spin angle θ influence on both of the surface roughness and stock removal of the ball.
In order to monitor amount and extent of damage on a surface of a workpiece, without removing a tool electrode from the workpiece, a new monitoring system for electrical discharge machining is developed. This system detects the discharge location and monitors whether each discharge is normal or abnormal. The monitored signals and the discharge location are displayed on a CRT display during machining. The damaged portion and the extent of damage on the surface of the workpiece are determined without stopping the machining operation or removing the tool electrode from the workpiece. It is useful to determine the cause of abnormal discharges and decide appropriate countermeasures based on the results of this monitoring system. This paper describes the detected accuracy of discharge location and the relationship between the damaged surface and the monitored signals are investigated.
Perforatability and thermal damages of dental hard tissues with two kinds of YAG laser are investigated for the purpose of making the cavity and forming the abutment tooth. The perforatability of dentin with laser beam depends on the absorptivity for laser beam, the laser power, the pulse duration and the number of laser pulses. Approximately 65% of Er:YAG laser beam is absorbed at irradiated surface of dentin, but the absorptivity for Nd:YAG laser beam is only 17%. High perforatability is accomplished using Er:YAG laser because of its higher absorptivity. There is a linear relation between the perforated depth and the number of pulses. Higher laser power and larger pulse duration improve the perforatability, in the same time, induce thermal damages on dental hard tissue such as thermal cracks and burning of dentin. Lower laser power and smaller pulse duration makes it possible to make fine cavities without thermal cracks and burning in even with Nd:YAG laser.
Biomachining is a novel machining technology and is different from the traditional physical and chemical machining methods, in which biological energy of bacteria is used as a main energy source for machining process. Previous report has made it clear that the machining speed becomes higher under proper shaking rate and temperature, higher efficient process can be achieved under electric field, and so on. However, the material removal mechanism has not yet been clarified sufficiently. In this report, the material removal mechanism in biomachining was discussed, by comparing the material removal rate for iron and copper. The experimental results indicate that, in the material removal, bacteria acts on the material not only directly, but also indirectly, that is to say, bacteria promotes the change from Fe2+ion to Fe3+ion which has powerful oxidizing effects and makes the material dissolved. Furthermore, the effects of cultured fluid flow on machining characteristic were investigated. As a result, the cultured fluid flow significantly influences the machining rate, and high efficient machining can be achieved by jetting out the cultured fluid from nozzle with high flow rate.
SOI (Silicon on Insulator) wafer is expected as a semiconductor substrate which realizes the high-speed and low-power device for the next generation. In this report, the result of thinning the SOI layer of the SOI wafer by using the numerically controlled plasma CVM (Chemical Vaporization Machining) apparatus is described. In plasma CVM, since the removal volume is proportional to the dwelling time of the plasma, numerical control machining is realized by controlling the scanning speed of the worktable. Scanning speed distribution for obtaining the target film thickness can be decided by, measuring the pre-machining SOI layer thickness distribution and removal rate per unit time, and the thickness distribution of the SOI layer was measured by spectroscopic ellipsometry. The sample is the commercial SOI wafer (6 inch UNIBOND wafer), and SOI layer thickness before thinning is about 200nm. As the result of thinning the SOI layer by the numerically controlled plasma CVM, the order of 10 nm of the SOI layer was achieved.
This study deals with the in-situ heat treatment system including quenching and tempering processes using YAG laser In the present report, the tempering conditions were investigated to obtain the adequate hardness. Moreover, a theoretical model based on the diffusion equation was proposed to predict the hardness after laser tempering. Then, it was confirmed that theoretical results were in good agreement with the experimental results obtained from this system. Hence, this model is effective to predict the hardness after laser tempering. Consequently, it was demonstrated that the heat treatment process of the quenching and tempering can be done using YAG laser
This paper proposes AGV (Automated Guided Vehicle) navigation methodology by using two cameras and artificial landmarks. This method doesn't need high cost sensors and doesn't have to model motion errors of AGV. It is proposed that (a) a landmark arrangement planning algorithm in a given working environment of the AGV, and (b) a landmark observation planning algorithm along a given path of the AGV. Navigation experiments with a real AGV show the effectiveness of the proposed methodology.
Preparing tissue sections for light microscopy is absolutely necessary in pathology. This process, however, is still mainly performed manually. Preparing many samples from a large number of specimens requires great skills. Additionally, it is very difficult to maintain predetermined accuracy of the procedure. To solve these problems, we propose a new prototype machine for automatic sample preparations. We developed the machine for automatically mounting sections on the object glass by using static electricity. The principle of this method is based on electrostatically charging the surface of a paraffin block, by which insulation tape is attracted to the surface. After sectioning the block, the section remains adhered to the insulation tape by electrostatic force. Then, the section is transferred to the object glass by using the static electricity again. This whole process can be repeated automatically and the sectioning is performed by the newly developed high-precision automatic microtome. With this machine, the process covering from sectioning to transferring the tissue section on the object glass can be done full-automatically.