Advanced Materials Research Vol. 1017

Abstract: The surface of a grinding wheel dressed by a diamond rotary dresser was generated by computer-aided simulation for the case of multipass dressing on the assumption that the grinding wheel is a homogeneous solid body and the dressing trajectories of the diamond grits are perfectly copied on the grinding wheel surface. The dressing process was visualized as a contour map of the dressed surface profile and the effects of the dressing strategy, i.e., down-cut dressing or up-cut dressing, on the grinding wheel removal process were investigated. It was found that the diamond grits remain the residual depth of cut on the surface of the grinding wheel, resulting in an actual depth of cut larger than that given by the rotary dresser.

Abstract: The grain orientation plays a great important role during single grain grinding. Single grain grinding simulation could offer an insight into the material removal behavior. However, grinding simulation with FE methods has problems arising from large deformations at the chip root and negative rake angles of the grain. In this work, a coupled Eulerian-Lagrangian method (CEL) is used to model the grinding behavior of single diamond grain in different orientations. The influence of the grain orientations on the grinding forces, grinding process (sliding, ploughing and cutting) and critical undeformed chip thickness are analyzed. The force ratio shows great accordance with the analytical calculation data. The simulation results show that the chip generates quickly and the special grinding force is relatively small when the diamond particle is in octahedral orientation (111)-(100). The workpiece material flows to the side and front owing to the pressing of cutting crystal face. The swelling of the material is generated beside the abrasive grain. The range and height of swelling are increased gradually and kept invariant after chip formation. The deformation of workpiece material contacting with grain edge is very severe. Therefore the biggest residual stress appears at the grain edge of the groove.

Abstract: There is a compelling need for development of a surface grinding machine for 450mm diameter silicon-wafers. The authors have developed a new surface grinding machine for the large scale silicon-wafers. The machine has a rotary work table equipped with a constant-flow hydrostatic water bearing. The table system has to attain high static stiffness to achieve higher loop stiffness. This paper investigates static performances of the rotary table by numerical computation. The obtained results are compared with the experimental ones. Accordingly, it is verified that the developed rotary table has sufficient static performances for the large scale silicon-wafer grinding machine.

Abstract: We present the fabrication and optical testing of a fine grating on a ZnS substrate to be used as a wideband infrared spectral disperser and for which the primary application is measurement of the composition of the atmospheres of transiting exoplanets using space-borne infrared astronomical telescopes. A grating with a blaze angle of 2.1 deg. and pitch of 166.667 μm was constructed on a roughly flat 10 mm × 10 mm substrate with a maximum thickness of 1 mm. To obtain high accuracy, the sample was fabricated on a ZnS monocrystal using a high performance processing machine at Canon Inc. The surface roughness measured with a microscope interferometer was 2.6 nm rms. The shape of the fabricated grating edges was examined with a scanning electron microscope. The diffraction efficiency was evaluated by optical experiments at λ = 633 nm, 980 nm, and 1550 nm, and compared with the efficiencies calculated using a Fourier Modal Method. The results showed that the differences between the diffraction efficiencies obtained from experiment and by calculation were between just 0.9 % and 2.4 %. We concluded that the quality of the fabricated ZnS grating was sufficiently high to provide excellent diffraction efficiency for use in the infrared wavelength region. We also present the design of a spectral disperser in CdTe for future more advanced performance.

Abstract: In this paper, we propose cutting-force-estimation method for a ball-screw-driven system using triple inertia model. In many cases, dual-inertia model is applied to describe the dynamic behavior of the ball-screw-driven system. In this paper, triple-inertia model is applied and cutting force was estimated without additional sensors, such as dynamometer. The cutting force observer is designed, regarding the ball-screw-driven system as two input and three output system. Simulation results indicate that the proposed method enables accurate estimation around the resonance frequencies. Experimental results showed that the proposed method could monitor external force without being interrupted by the inertia forces.Nomenclature

Abstract: Nowadays, infrared thermographic technology has been attracting attention in various industrial fields. We therefore focus on it as a novel method for monitoring tool temperature to improve end-milling conditions for difficult-to-cut materials. However, a problem has emerged; it is difficult to measure the tool temperature when there is a coolant because the coolant prevents monitoring of the surface of the end-mill tool. Thus, we developed a wireless tool holder system equipped with a thermocouple in the end mill to monitor the tool temperature under coolant conditions. In this report, we compared the temperature measured by infrared thermographic imagery with that measured by a wireless tool holder system when end milling the stainless steel under dry coolant conditions. The thermocouple, which has a small diameter of 0.12 mm, was used to ensure high response measurement in the proposed wireless tool holder. We obtained the tool temperatures by infrared thermographic imagery and by wireless tool holder equipped with a thermocouple at a sampling time of 1/30 of a second. We confirmed that the temperature measured by the wireless tool holder agrees with that measured by infrared thermographic imagery. As a result, we demonstrated that the developed method with a wireless system is effective to estimate the tool temperature in end-milling processes and makes it feasible to measure it under coolant conditions.

Abstract: A new developed TiN-TiB₂ ceramic cutting tool material (marked as TBN5) with high comprehensive mechanical properties was fabricated by the in-situ integration synthesis process. The cutting performance of TBN5 tool in continuously turning the austenitic stainless steel 1Cr18Ni9Ti was experimentally investigated; the failure modes and failure mechanisms of the cutting tool TBN5 were analyzed combined with its mechanical properties. Aiming at the materials removal amount, the optimal cutting parameters of TBN5 tool in turning 1Cr18Ni9Ti were firstly obtained by the orthogonal tests; and then with this cutting parameters, the cutting performance of TBN5 compared to the commercial tools LT55 and SG4 was studied. The results showed that the advanced tool TBN5 could get longer tool life than LT55 and SG4; the main failure modes of TBN5 were flank wear, breakage and the flaking of main cutting edge. The scope of its flaking was smaller and diffusion wear was not obvious, which was related to the higher fracture toughness and the higher thermal conductivity of TBN5.

Abstract: Nowadays, resource saving technologies have become important because of increasing global environmental problems. Moreover, demand is increasing for the manufacturing and machining of small mechanical parts because of the downsizing of electronic mobile devices. Thus, one requirement has emerged that these small parts have to be fabricated by smaller machine tools to reduce the environmental burden. Here, when we look at the heat treatment process, it is found that most small parts are generally treated with a large size furnace as well. Therefore, we focus on compact machine tools to develop the clean and energy-saving technology in the manufacturing fields. In the present report, we consider an in-situ laser heat treatment technology integrated on the table used for compact machine tools. In particular, we perform the entire laser hardening of a small thin plate with a small power semiconductor laser, which is an attempt to harden a whole steel sheet. However, thin plates deform during the laser hardening process, which is called “laser forming.” Thus, we discuss an effective irradiation path to prevent the deformation of plates while quenching the entire plate. Moreover, considering the power consumption in the laser quenching process, we investigate an appropriate laser irradiation condition.

Abstract: Recently, there has been an increasing demand for miniaturization and multi-functionalization of electronic equipments due to the developments in information technology (IT). Thus, the miniaturization of printed wiring boards (PWBs) and fabrication of highly dense electrical circuit layers are needed to realize the miniaturization and densification of the semiconductor package PWBs. Micro-drilling technology has been attracing attention to machine the electronic micro-through holes with an ultra-high-speed spindle, more than 160 krpm. However, problems have emerged; the drill tool bends and suffers breakage in the drilling process and the heat damage around the drilled hole after a drilling process occurs due to the increase in the drilling aspect ratio between hole depth and diameter. In general, a step feed drilling method is considered an effective way to solve these problems. However, short stroke alternating motion in the spindle axis is needed to do the step drilling process and its motion causes various kinds of vibration. We constructed a machine tool with a novel counter balance mechanism in the spindle driving Z-axis and investigated a model to estimate a proper balance mass for the step drilling process. We compared the frequency response results from a proposed model with the experimental ones, and discussed a control on vibration due to the counter balance mechanism. The results demonstrate that a proposed vibration proof method was found to reduce the vibration in high-speed step-micro-drilling motion and to improve the drilled hole quality and the efficiency of micro-drilling process in the PWB manufacturing fields.

Abstract: Fixed-abrasive wires, such as electroplated diamond wires and resinoid diamond wires, employed for slicing ingots have the problems of high tool wear. A novel brazed diamond wire has been developed to overcome these problems. This paper investigates the effect of process parameters, including brazing temperature, brazing time and brazing filler composition, on the brazed diamond wire manufacturing with CuSnTi brazing filler. The 3D micro-video system was used to observe the brazed diamond wire surface. Tensile, bending and torsional test were carried out to evaluate the mechanical properties of brazed diamond wire. A brazed diamond wire with 3km length was fabricated with the optimization process parameters, which was successfully used to slice glass.