The authors have recently researched interesting phenomena on lapping tests for a glass on a silver lapping plate using different quaternary ammonium chloride solutions. The silver lapping plates were not worn during the lapping process even under the condition of large stock removal of the glasses. In this research, glasses, silicon wafers and ceramics were used as lapping plates for lapping test in the various quaternary ammonium chloride compound solutions as suspensions with aluminium oxide abrasive grains. It inquired into relations between the phenomena and concentration of NaCl, KCl, NH4Cl and ZnCl2 solutions, too. The surfaces of silvers were observed by SEM and EDX after lapping test. In the case when NaCl, KCl, NH4Cl and ZnCl2 lapping solutions were used on glass lap plate, also stock removals of silvers become zero. Any differences of structures on the silver surfaces were not observed after lapping by SEM and EDX even if this phenomenon occurred or not.
This paper deals with an experimental investigation of high-speed face milling of polybenzimidazole (P.B.I.) using a fine crystalline diamond coated tool which has reshaped sharp edge. Especially, the effects of a sharpened cutting edge and an increasing cutting speed on machined surface are investigated. It has been confirmed that the edge of a diamond coated tool could be reshaped in a sharpened form by a heat chemical polishing. The diamond coated tool which has a reshaped edge is superior to a normal coated diamond tool in machined surface with little damage by cracks. Moreover, this tool when it has a rake angle of 10 degree is effective in controlling cracks. Furthermore, as a result of the investigating the effects of different speeds on damages to a machined surface, it is clear that the best machined surface with very little damage is obtained at a cutting speed of 40.0 m/s. At less than 40.0m/s, the damage was determined by mainly micro-crack and, on the other hand, tear damage to the machined surface was observed at speeds beyond 40.0m/s. The viscoelastic behavior of P.B.I. material accompanying change of cutting temperature had influenced these kinds of damages, and it showed clearly for the temperature of 650K which begins to produce the viscosity to be equivalent to cutting speed 40 m/s. Also, a drop in the bending strength after cutting can be limited to 2%.
For high efficiency production of high quality components, the high removal rate ultra-smoothness grinding method which can finish to almost the same smoothness formed by polishing is previously developed and ascertained to be useful for finishing to the surface roughness below 30nm (Rz) or 5nm (Ra). In the previous report, however, the surface flatness in the large area beyond 256μm square is not discussed. In the report, the influence of parallel step feed closely related to geometrical surface roughness on the surface flatness is examined by measuring the surface flatness of 4mm square and 50mm×40mm area together with the surface roughness of 256μm square. In the region of parallel step feed over the critical value the surface roughness becomes worse, which result is different from the geometrical surface roughness obtained from the concept of new ultra-smoothness grinding method. In the region of parallel step feed below the critical value, on the other hand, the slight undulation corresponding to the surface flatness of 4mm does not become better with the decrease of parallel step feed and is kept in a given constant value. The surface flatness of 50mm×40mm area formed by the grinding of silicon carbide is about 500nm (Rz) or 75nm (Ra) at two dimensional measurement though the surface roughness attains below 20nm (Rz) or 4nm (Ra) in 256μm square.
Recently, a linear ball guideway is often used for precision and ultra-precision positioning. Rolling elements such as linear ball guideways have static characteristic called Nonlinear Spring Behavior (NSB) in minute displacement. And these rolling elements have frequency response characteristic of dynamic characteristic when positioning. As this characteristic has resonant point and the guideway vibrates, it is very difficult problem to achieve the precision and ultra-precision positioning. Measuring dynamic characteristic is not easy and takes times. Then, the precision positioning device of an axis using a Voice Coil Motor (VCM) is composed to measure the NSB and the frequency response. Resonant frequency presumed from the spring constant of the obtained nonlinear spring behavior and damping ratio presumed as a function of displacement using least square method correspond to ones of the frequency response respectively. Therefore, this paper shows that it is possible to estimate the frequency response characteristic only using result of the nonlinear spring behavior.
Surface topography is generated by the cutter marks of ball-end mill. It has been reported that the surface topography is determined by the eccentricity and tilting angle of tool axis and phase difference of cutting edges. However, the surface topography machined practically based on the theoretical cutting conditions is in disagreement with the simulated one. In this paper, influence of acceleration/deceleration and spindle speed deviation on cutter marks array has been investigated by changing the phase difference of cutting edges. From the experimental and simulation results, it is shown that the cutter marks array is changed by acceleration/deceleration of corner tracking motion. This cause is that a decrease in the tool traveling time by the tracking error changes the phase difference of cutting edges. In addition, it is found that a small deviation of the spindle speed to the input command in the NC data bring a big change to the cutter mark array.
‘Ultrasonic elliptical vibration cutting’ technology is applied in the present research to ultraprecision machining of tungsten alloy, which is expected as a material of molds for glass parts instead of sintered tungsten carbide or CVD-silicon carbide. It is confirmed that ulptraprecision grooving of the tungsten alloy cannot be realized by the ordinary cutting. On the other hand, it can be realized by the elliptical vibration cutting at a cutting depth of less than 0.8 μm. Effects of the cutting distance on the cutting force and the surface roughness are also clarified, and it is found that surface roughness of less than 100 nm Rz can be attained up to a cutting distance of 35 m. Practical molds of the tungsten alloy for spherical glass lenses and a glass prism are successfully machined by the elliptical vibration cutting.
This paper presents a new machining technology of die/mold to keep constant cutting force by controlling both the feed rate and the spindle speed depending on the machining profile. First, we measure the control capacity of spindle speed on up-to-date machining centers and confirm that they have the acceleration rate up to 100/s2. Under the control of feedrate and spindle speed, cutting tests of hardened steel with sinusoidal shapes are conducted by using a square end mill. Experimental results show that newly developed method is very effective for cutting die/mold in high accuracy and high productivity.
In conventional chucking-system, workpieces such as thin-walled components and low-rigidity parts. have been deformed by chucking-force. And they could not be chucked by the magnetic property of a workpiece. The purpose of this study is to develop a new chucking system, in which the chucking force does not act on the workpiece directly. In the new chucking system, the workpiece can be chucked regardless of magnetic property of the workpiece. The characteristics in which the ice adsorbs the thing is applied. A thermoelectric element is used in order to cool the chucking plate. The high temperature side of the thermoelectric element is radiated by the compressed air. This new chucking system can be used in anywhere, if there is the compressed air. In this study, a design manual for an air-cooling chuck system is proposed, and the validity of the design manual is examined on a basic design by FEM. The performances of the air-cooling chuck are verified by temperature characteristic, adsorption force and cutting test. The test results verify the effectiveness of the proposed systems for practical application.
Some differences of the cutting phenomena caused by materials and hydrous property in the cortical and cancellous bones are discussed in this paper. They are summarized as follows. (1) Although the cutting behavior with brittle fracture is observed in the dry cortical bone, the continuous chip formation is observed in the wet cortical bone even if a large depth of cut is applied in the cutting. From this result, it is suggested that the property of wet bone may be changed by the contained water. (2) It is easy to form the continuous chip even in the across cutting direction on the wet cortical bone section, which is difficult direction to cut, because water in the bone may increase toughness of the bone tissue. (3) Cutting of the trabeculae in the cancellous bone is brittle and soft cellular tissue in the trabeculae is easy to deform. But soft adhesive bone materials is discharged on the tool rake surface as a cutting chip. Consequently, it seems that the behavior of cutting and the chip formation for cancellous bone depend on the soft tissue.
In this paper, we present a parametric deformation method for mesh models based on barycentric coordinates for convex polytope. First, we propose a FFD (free-form deformation) based on barycentric coordinates. Arbitrary convex polytope can be used for the deformation handle of the FFD. Next, we propose an automatic handle construction method for the FFD based on definition and classification of deformation types. Deformation handles suitable for user intended deformation types can be automatically constructed by selecting the deformation type and model portions to be deformed. Finally, we propose a parametric handle deformation method driven by the affine transformation. In our method, user can deform the model by selecting deformation type, portions to be deformed, and by manipulating one or two deformation parameters. Moreover, we propose a method for preserving approximated geometric continuity at the boundary between deformed portions and non-deformed portions of the models. For this purpose, we impose geometric constrains derived from analysis of derivatives of barycentric coordinates on the deformation handle for each deformation type.
A birefringence in the next generation of DVD pickup lens is one of the important factors of evaluation. A precise measurement of birefringence is required because an astigmatic aberration by birefringence distribution causes degradation of pickup signal. A purpose of this paper is to construct two- dimensional measurement of birefringence on a pickup lens. A null lens method is proposed to prevent beam expansion by sample lens. Sixteen images captured by CCD camera are adopted to analyze both retardation and principal azimuth by local-sampling phase shifting.
In the field of vibration control, the servo type acceleration sensors are widely used. For the measurement of seismic intensity and the vibration suppression control of bridge or high-rise building, the servo type velocity sensors are commonly utilized. In either case, the velocity sensor is convenient for the vibration control, because an integration operation is unnecessary to derive the velocity signal. Then, in order to improve the velocity sensor, the velocity sensor using the calibration coil was already proposed. In this paper, the displacement sensor using its coil is furthermore proposed. This sensor has the merit of simultaneous vibration detection. Namely, the acceleration, the velocity, and the displacement signals can be detected from the closed loop at the same time. Firstly, the principal control block diagram of displacement sensor is presented. Next, improved results for both the generated offset voltage and the excitation of high frequency dynamics are shown. Finally, the shaping condition of frequency response and results of parameter identification are experimentally shown. For impact test of structure, the acceleration, the velocity, and the displacement signals can be detected simultaneously.