The high removal rate ultra-smoothness grinding method which can finish to almost the same smoothness formed by polishing has been recently desired strongly for high efficiency production of high quality components. In the report, the existing of limiting smoothness, which can be attained in traverse grinding is discussed theoretically and presented experimentally. On the basis, the newly devised ultra-smoothness grinding method is proposed and ascertained to be useful for finishing to near the ultra-smoothness surface. In the new method, first of all, the workpiece-wheel contact width is ground by feeding toward the direction normal to grinding direction (wheel revolution direction). Next after the workpiece is slightly step-fed to the direction parallel to grinding direction so that the geometrical surface roughness formed by overlapping the cross-section of two wheel circles before and after the step-feed is lower than the required surface roughness, the workpiece-wheel contact width is ground again by feeding reversely toward the direction normal to grinding direction. The whole surface of workpiece is finished by repeating such a grinding process. The surface roughness of cemented carbide tool formed by the ultra-smoothness grinding method using the #140 diamond wheel is found to attain below 30nm(Rz) or 5nm(Ra).
A new compensation method that enables not only to improve the geometric accuracy of a machining center but also to improve the workpiece accuracy has been developed. The strategy of our evaluation and compensation method utilize coordinates measuring machine (CMM) as a master gauge because of its accuracy so that machine operator devote himself to machining and estimator of accuracy dedicate in measurement. As each operator knows the characteristics of machining center and/or CMM, the results obtained are enough reliable to evaluate the accuracy of both machining center and workpiece. The geometric error is evaluated from results of both the profile and position of boring centers with the workpiece prescribed in JIS B 6336-7-A320. The measured data contain not only geometric error results from mother machine but also various errors such as thermal elongation, tool deformation, transient machine displacement by hydraulic lubrication and so on. In our study, these errors except the geometric accuracy of a machining center are neglected by setting the cutting condition not to affect the desired machined workpiece previously. The total pitch error and geometric error are predicted by using the transform formula including error parameters measured by CMM. The predicted results are enough accurate to compensate geometrical error and position error as the inverse problem. In this report, the effects of predicted results and compensated results are shown with the experimental procedure.
The machinability of wear-resistible cemented carbides and the tool wear behavior in machining of V30 and V50 cemented carbides using PCD (Poly Crystalline Diamond) cutting tool was investigated to understand machining characteristics. This material is one of the difficult-to-cut materials in present, but their usage has been already broadened to every commercial applications such as mining tools, and impact resistant tools etc. Summary of the results are as follows. (1) Tool wear progression of PCD tools in turning of wear-resistible cemented carbides were observed specially fast in primary cutting distance within 10m. (2) Three components of cutting resistance in this research were different in balance from the ordinary cutting such as that cutting of steel or cast iron. Those were expressed large value by order of thrust force, principal force, feed force. (3) If presume from viewpoint of high efficient cutting within this research, a proper cutting speed was 15m/min and a proper feed rate was 0.1mm/rev. In this case, it was found that the tool life of PCD tool was cutting distance until 230m approximately. (4) In cutting of wear-resistible cemented carbides such as V30 and V50, it was recognized that the tool wear rate of V30 was very fast as compared with V50. (5) When the depth of cut was 0.1mm, there was no influence of the feed rate on the feed force. And the feed force tended to decrease as the cutting distance was long, because the tool was worn and the tool edge retreated. (6) It was observed that the cemented carbides were adhered to the flank.
This paper deals with the surface topography and grinding mark on the surface, which is ground by high-speed reciprocation grinder. The vibration of the wheel spindle forms the grinding mark. Therefore, the imbalance of grinding wheel, which causes the vibration, should be eliminated. However, it is impossible to eliminate the imbalance from grinding wheel completely. The influences that the wheel spindle vibration gives for ground surface must be made clear. And the influence of wheel spindle vibration must be controllable. In this paper, the ground surface is measured by form measuring instrument to investigate a surface topography. It is found that there is periodic micro topography on the ground surface, and shape of the micro topography changes by a difference of grinding marks. It indicates that the ground surface topography can be controlled if the grinding mark can be controlled. Therefore, the relationship between grinding mark and grinding parameters is investigated theoretically. As a result, it becomes clear that the grinding mark varies sensitively following the variation of the wheel vibration frequency or table reciprocation frequency, and the grinding mark generated by conventional grinding is easier to vary than by high-speed reciprocation grinding.
As multi-task machines have been popularized, their overall motion accuracy becomes of more importance as is on conventional machining centers, even for lathe-type machines on which only the X-axis accuracy was conventionally considered important. In this paper, we present the improvement of the overall accuracy of a multi-task machine by using the DBB method, which has been widely used to improve the overall accuracy of machining center. Experimental studies show that it is important for lathe-type multi-task machines to reduce angular errors caused by the construction of the machine. By controlling such angular errors, the target overall motion accuracy, 10μm or below, can be achieved.
The multi-wire saw is one of the methods used to slice large-sized silicon ingots. This slicing method uses a working fluid mixed abrasive grains, which is called slurry. In the case of a multi-wire saw of the workpiece descent-type, this slurry is supplied on the wire and carried to the processing area. As the workpiece is processed by slurry which enters between the wire and the workpiece, the slurry action is very important to the slicing efficiency and the accuracy of silicon wafers. In this study, the slurry actions on the periphery of the wire and inside the slicing groove are observed by a high-speed video camera. The slicing characteristics were studied under a series of slicing conditions using the workpiece descent-type multi-wire saw. From this study, the followings have become evident: (1) The slicing grooves are filled by the slurry, and the wire running brings about the slurry flow to the slicing grooves. (2) Air enters into the slicing grooves by the wire running, and some bubbles and air layer can be observed in the slurry of the slicing grooves. These are factors which contribute to lower slicing efficiency and accuracy.
ELID (Electrolytic In-process Dressing) grinding method was used as a surface fabrication process for metallic biomaterials (Ti-6Al-4V alloy), and ground surfaces were analyzed by a Scanning Electron Microscope (SEM) equipped with an Energy Dispersive X-ray Spectroscopy (EDX). To measure the thickness of surface oxide layer, detailed observation was also performed by a Transmission Electron Microscope (TEM). Electrochemical corrosion tests were carried out using a three electrode electrochemical cell connected to a computer driven potentiostat. The finished surface ground by the ELID grinding method showed higher corrosion resistance compared to the surface finished by polishing. This is because the ELID grinding method created a thick oxide layer. Consequently, the ELID grinding method appears to offer significant future promise for use in biomaterials and other engineering components subjected to corrosion.
This paper describes an optimization method of cutting conditions of milling process by analytical approach with the aid of a tool database system. First of all, a database system for milling operations is proposed. This database system can store not only information of machine tools, tools, and holders, but also the tool assembly state. Cutting conditions can be stored associated with the information of tool assembly and its machining state. Through this database, we can get tool geometry and cutting conditions based on past milling operations for the given milling tasks. Secondly, cutting force and machining error caused by deflection of tooling system are predicted by developed simulation system. It helps the tool selection and the decision of cutting conditions. Machining error is analyzed under various feed rate, radial depth of cut and axial depth of cut to investigate the influence of cutting conditions. Then it was found out the area where machining error becomes constant even if axial depth of cut or radial depth of cut increases. By expressing the relationship between cutting conditions and machining error using multi-regression analysis, it was shown that better cutting conditions could be obtained in the viewpoint of machining error and machining efficiency than the cutting conditions derived from the database.
The crack-free removal of material, known as ductile mode machining, has been achieved by a very small depth of cut. In this study, the nano-scale layers of single-crystal silicon surface are machined by micro-Vickers hardness indenter witch is assumed to be a single abrasive grain. The subsurface crack as well as the surface crack are observed by a scanning prove microscope and a scanning laser microscope. When surface cracks are not observed by decreasing the depth of cut, the machining has been commonly considered to be in ductile mode. Although crack-free machining seems to be accomplished, the subsurface crack progress under the groove. The transition point determined by the subsurface crack is found to be a more shallow depth of groove than the point by the surface crack. Therefore the evaluation of the subsurface crack is significant especially in finish machining. The dependency of the depth of the subsurface crack on crystallographic direction is revealed. This dependency is due to the fact that mechanical properties of single-crystal silicon are affected by the crystallographic direction.
This paper presents a new dynamic model of nonlinear friction in a ball guide way. This model includes Coulomb friction, viscous friction, Stribeck effect and nonlinear behavior of elastic deformation. By the proposed model contrary to the conventional one, the motion is not decelerated but accelerated by the elastic recovery force just after the direction is reversed This model is not symmetrical for the zero speed of motion. In our simulations the friction models of the proposed and conventional were tuned using Generic Algorithm and by applying these models the driving forces for the same reversed motion were also estimated. These simulations indicated the proposed model is much more accurate than the conventional one. The friction force compensation experiments considering the proposed model were carried out by using a linear slider for a motion in which the velocity was reversed. The tracking error was reduced to less than a half of that without compensation.
For three dimensional positioning of a complex three dimensional mechanism flexibly, it is needs to measure three dimensional displacement of an end-effecter of the mechanism in the high precision by non-contact method. It was common to put the plural sensor or scale together and to measure the three dimensional displacement of the mechanism. However, it is difficult to calibrate positions and sensitivities of the plural sensor or scale. Therefore, the novel three dimensional displacement measuring method is proposed using the optics that focus is collected in the center of the spherical target which has been used for the radius measurement of the ball. Instead of high sensitivity on measuring in the XY direction, new ideas are necessary for the measurement in the Z direction in this optics. Therefore, a ring beam is used instead of the simple ray for Z direction measurement. The theoretical examination and simulation of the three dimensional displacement measurement using the ring beam are done and that validity is confirmed by the series of the experiments.
The study deals with the development of a drilling robot traveling inside a pipeline. Aiming at inexpensive anti-corrosion and repair of underground pipes, a new method was established and has been widely employed, in which the internal wall of the pipes is coated with some pieces of material or resin layers. However, the coating method has a disadvantage of closing the inlets of pipes connected to a coated pipe. Accordingly, the inlets must be opened again from the outside of the pipe by means of excavating works, which cause high cost and a lot of waste time, and so on. Thus, a movable drilling robot is developed to make the inlets again without excavating works. It can move inside the pipe, search the closed inlets to the connected pipes, and drill holes in the closed inlets. The robot consists of a drilling module for machining holes in the closed inlets, a tool positioning. module for searching drilled points, determining the tool position and checking the drilled holes, and a moving module traveling inside a pipe for carrying the above-mentioned modules. From the demonstration experiments, it is found that the robot can move inside the coated pipeline, find the closed inlets, position a tool, machine holes and check the holes.
Fracture behaviors of TiN thin films and their dependence on substrate materials are clarified by in-situ surface observations of TiN thin films under tensile stress using AFM (Atomic Force Microscopy). The system has the ability to observe surface structures with atomic resolution under uni-axial tensile force. Specimens of TiN thin films on Si, Au and Pt substrate materials were prepared. The TiN thin films were deposited on Si test chips by electron beam evaporation in Na atmosphere. The Au and Pt substrates were prepared on the test chip before TiN deposition by magnetron spattering. Three types of surface patterns that depended on the elasticity and thickness of substrate materials were observed. TiN thin films deposited on Si, Pt substrates showed periodic cracks that were perpendicular to the tensile force irrespective of substrate thickness. The periodicity in TiN thin films was explained by the Grinfeld instability. However, TN films on Au substrate showed strong dependence with substrate thickness. When the substrate thickness was below 20 run, the same crack patterns were observed, but the crack length tended to be repressed with increasing thickness. TIN films on Au substrates that were thicker than 60 nm exhibited a large number of small dotted cracks. These dramatic changes of fracture patterns were attributed to the stress relaxation of substrate materials.
The aim of this paper is to determine experimentally the elemental data regarding the short term growth of plants when two mechanical stimuli -low frequency vibration and artificial wind- are given to plants during a short period. Accordingly, a basic study was carried out determining experimentally the moisture transport quantity in the plant, suggesting a macroscopic moisture transport model based on the experimental result, and attempting a fundamental elucidation of the moisture transport mechanism. The plant used as the experimental target was the golden pothos (a kind of foliage plant) which can grow by water culture throughout the year. The moisture transport quantity in the plant was measured after the application of low frequency vibration and artificial wind to the plant. The results demonstrated that the addition of mechanical stimulation by wind and vibration was related to an increase of the amount of water transported in the plant. Furthermore, an electronic circuit model, which is a moisture transport model of the plant inside, was constructed with a transistor. It was confirmed that this model could express the measured value of water rising in the plant in terms of the difference between the two mechanical stimuli.
The authors have been developing cellular machines that consist of homogenouse or a small number kinds of units celled cells with high modurality and autonomy. Cellular machines exhibit advantages in fault-torelance, flexibility, and reconfigurability. We have already developed a cellular automatic warehosue as an example of cellular machine, and demonstrated its fault-tolerance and flexibility through computational simulation and hardware experiment. In this paper, we illustrate the development of a cellular manufacturing system as an extension of the cellular automatic warehouse.
Work motion recognition is an important function for computer support systems to provide novice workers autonomous instruction by monitoring human behavior. Since manual work, such as assembling work, is performed by seamless motion at variable speed, it needs special solution in pattern matching problems. This paper proposes one type of syntactic pattern matching method for motion recognition in human work. The proposed algorithm has two steps of pattern matching. The first process is to divide a time series of motion data into a relatively short time motion by defined conditions, and to assign a symbol of motion type to the portion data. The second one is to compare the symbol stream with work models. In this process, Dynamic Programming (DP) matching method is used. Experimental results show that the proposed method is effective to adapt the variable work speed even if short time motion model is used.
Proteome research in the medical field is expected to accelerate the understanding of disease mechanism, and to create new therapeutic and diagnostic concept. For protein profiling, this paper proposes a new methodology named CPDIB (Crude Protein Direct Blotting). In CPDIB assay, crude protein sample is directly immobilized on a hydrophobic membrane, and then the expression of molecules in the sample are analyzed quantitatively by using a special device, where the membrane is used as a field of immune reaction. The over-all structure of the special device is based on the conventional slot-blot device. Mechanical improvement in the air-tightness of the case holding the membrane realizes the direct blotting and results in the high performance of the stability in the immune reaction. This paper shows the mechanical structure of the membrane assembly called ImmobiChip and the evaluation of the protein profiling and its reproducibility.
Bolt nut units sometimes loosen due to a rotation of the screw thread under repeated axial loading. In the previous paper, the authors demonstrated that the self-loosening was caused by a relative slip between the expanded nut threads and the contracted bolt threads. In addition, it was shown that a tendency of the numerical results on the thread loosening showed good agreement with the experimental results. However, , the estimated values were not well agreed with the experimental values since the load distributions at the engaged screw thread were assumed to be uniform.In the previous paper, an amouunt of the loosening angle was measured by a microscope. In this paper, an amount of the loosening angle could be measured continuously by using an electric micrometer. In addition, by measuring the friction coefficients of the screw thread and the bearing surfaces an estimation whether loosening angle is occurred or not is made. As a result, it is shown that the estimated loosening angle of screw thread, taking the load distribution at the engaged screw threads in an initial clamping state and the bolt and nut deformations into consideration, are fairly consistent with the experimental results.