This paper deals with measurement of the gap length between end mill blank and grinding wheel model by digital camera. Transmitted light between the gap arrives on the sensor array pixel of digital camera, and the information of light quantity arrived on the array is output as the RAW data. Both boundaries of the wheel model and the end mill blank are numerically recognized from change in the RAW data. Gap length between two cylinders, and other gap length between end mill blank and grinding wheel model are experimentally obtained. It is clarified that the obtained gap length coincides well with the true gap length.
The ultra-smoothness grinding method based on the new concept, which can finish to almost the same smoothness formed by polishing method, in the previous research, is developed as the countermeasure answering the recently strong requirement about high efficiency production of high quality components. The surface roughness of various kinds of materials formed by the method using the #140 diamond wheel is ascertained to attain below about 50nm(Rz). Furthermore, in the 2nd to 4th reports, the influence of grinding parameters such as wheel speed, normal feed to grinding direction and parallel step feed on the surface roughness is investigated. In the report, the possibility of ultra-high depth of cut of grinding of brittle materials such as fine ceramics and glass is examined. In even the ultra-high depth of cut of 1000 μm, the surface roughness of silicon carbide ceramic and Al2O3-TiC ceramic formed by the ultra-smoothness grinding method using #140 metal bonded diamond wheel is found to attain below 60nm (Rz) and 80nm (Rz) in three dimensional measurement of 256μm square, respectively. And also the surface roughness of a glass becomes below 50nm (Rz) in the range of depth of cut below 30μm.
In the previous report, the new type of dressing method (SADFC dressing method), in which the bond is removed efficiently by circulating the dressing fluid into the contact area between the wheel and the rectangular column type of dressing stick is devised. Using the new dressing method, furthermore, the in-process dressing system in which the dressing fluid is circulated during the grinding operation is manufactured on trial and generally ascertained useful. In the report, the bond removal mechanism in the new dressing and the adequacy of excluding operation of dressing abrasives into wheel-workpiece contact zone are investigated. The dressing force in the new dressing method is much smaller than the popular dressing method in which dressing is done by pressing dressing stick to the wheel. The bond removal is done under a slight fracture and/or fall-off of CBN grains due to small dressing forces to those. The effect of cleaning nozzle used for excluding operation of dressing abrasives into wheel-workpiece contact zone becomes lower for lower table speed in plunge surface grinding. The setting position of cleaning nozzle influences on the effect of excluding operation.
Laser surface modification of Si wafer is a well-known method in the semiconductor industry. It has been repoted that scratching of the surface by an AFM probe induces surface phase transition on silicon (Si) wafer. This can act as an etching mask against potassium hydroxide (KOH) solution. In this study, a combination of formation of laser-induced surface periodic structure by low fluence femtosecond laser irradiation on crystalline Si wafer and anisotropic wet etching achieved the formation of the structures with different morphology from the conventional. Femtosecond laser pulses (800nm, 120fs) were irradiated on the surface of Si (110) in order to form periodic structures with the lowest fluence possible. After the structures formation, anisotropic wet etching by KOH solution was performed. The structures played as an etching mask to form the periodic structures with the aspect ratio more than 0.6 and the separation about the irradiated wavelength.
In milling with ball end mills of inclined surface, geometric quantities such as contact region between the cutting edge and the workpiece surface, undeformed chip thickness along the cutting edge and area of cutting cross-section vary with feed direction of the tool, so cutting forces and chip formation change with tool path. In the first and second parts of this investigation, to predict cutting forces and chip formation in milling for various tool paths, a cutting model proposed in previous paper was extended to the milling process in which both cutting edges of sphere and cylindrical portions engage with the workpiece. It was shown that the cutting forces and the chip formation in upward or downward milling for inclined surface can be predicted by using the developed cutting model and energy method. In this paper, the cutting model is applied to the milling process with pick-feed, and three components of the cutting force and the chip formation under various pick-feeds are predicted. It is shown that the tendency of variation of the cutting forces and the chip formation with tool rotational angle considerably changes by given direction of pick-feed, furthermore in the milling process for the tool moving downward on the inclined surface, interrupted cutting or continuous cutting takes place with magnitudes of pick-feed. Predicted results of the cutting forces are good agreement with experimental results.
Recently the welding of aluminum alloy has been strongly required for the lightening the electronic products, the automobiles and so on. Then the hybrid laser system was newly developed in order to perform the high efficiency and high quality welding of aluminum alloy. The high electric-optical conversion efficiency was achieved by the new diode pumped pulsed Nd:YAG laser. The hybrid system is consisted of a newly developed pulsed Nd:YAG laser and a continuous diode laser, and it can deliver two lasers by one fiber. Higher absorption of laser energy into the aluminum alloy can be expected under the continuous irradiation of diode laser (λ= 808 nm), since the absorption into aluminum alloy shows the maximum at λ= 850 nm. The suitable bead width and depth could be obtained with better surface integrity when the pulse waveform took the highest peak at the first period. The bead width and depth increased with increasing the power of continuous diode laser, which leads to overlapping welding even under high speed condition. Moreover, the high efficiency and high quality welding of aluminum battery case could be accomplished by the newly developed hybrid system, in which the suitable pulse energy and the peak power could be given even under the high pulse repetition rate.
A novel nano micro/nano fabrication process using functional nano particles is developped. Functional particle photsensitive resin is made by mixing functional micro and nanoparticles with photosensitive resin uniformly. Fundamental shape of micro parts are fabricated by using microstereolithography system: low temperature annealing procedure is applied to shrink the resin body of micro parts: during the annealing process, functional particles are moved and aggregated slowly in the elastic resin to inside via surface: functional particle are gathered on the surface of the micro parts. Micro 3D structure of functional particles are fabricated based on the proportional shrinkage of fundamental shape. In this report, we investigate the fabrication mechanism of 3D structures made of fine functional particles, and describe a fundamental experiment to form the micro electrode made of Ag nanoparticles.
Vibration finishing which is a newly developed abrasive finishing method is often applied to the metal surfaces recently. However, an application of this finishing method and an evaluation of finished surfaces require skill which depends on sensory examination. This is because the relations between finishing conditions and quality of finished surfaces are not clear. And the quantitative evaluation of them has not been done. The aim of this research is to evaluate the vibration finished surfaces quantitatively. The vibration finishing was carried out using a disk-type finishing tool with movements of rotational and orbital motion on stainless-steel plate surfaces. For taking photos of finished surfaces, the finished surfaces were lit up with LED illumination from two directions and photos taken from two directions were analyzed for detecting the differences between them for estimating the finished surface characteristics. And a quantitative evaluation of the vibration finished surfaces was examined, using textural features calculated from the gray level co-occurrence matrix and 2-D DFT obtained from the surface images of them. As a result, differences of textural features between vibration finished surfaces and circular hairline finished surfaces were clarified. Moreover, effectiveness of the quantitative evaluation method was confirmed by comparing the evaluated results obtained from skilled workers.
This study describes the machining of the fine surfaces with a ball nose end-mill tool by a five-axis controlled machining center. In the present paper, we demonstrate that it is effective to maintain a constant contact angle between an end-mill ball nose and a work surface in machining in order to obtain the fine machined surface because this makes it possible to avoid an irregular luster (striped pattern) caused by a profile error of the ball nose on the machined surface. Moreover, it can be seen that the surface roughness (i.e., convexities and concavities) along the tool feed direction can not be overlooked in trying to obtain the fine machined surface such as a mirror surface. As a result, a new method is proposed to determine the optimum cutting condition to achieve the minimum cutting time considering the surface roughness along the pick direction and the feed direction under a constant surface roughness.
Novel cutting tools that had either microscale or nanoscale textures on their surfaces were developed in this study. Texturing microscale or nanoscale features on a solid surface allowed us to control the tribological characteristics of the tool. In this report, diamond like carbon (DLC) coated tools with the texture were developed using a femtosecond laser and subsequent DLC coating methods. By applying DLC coating, the effects of the texture were evaluated without adhesion of a work material due to its low adhesion rate and application of the texture to coated tools can also be investigated. Turning experiments of aluminum alloy were performed under the various cutting conditions. It was found that the wet condition was suitable for the developed tool and the further decrease in cutting forces were observed when the texture was applied to the DLC coated tools. The tendency of the direction of the texture was similar to that of the noncoated textured tools, which indicates that the difference in the effect of the texture was decided not only by the adhesion characteristics of the work material but also by other factors. The effects of the texture were observed even at the low cutting speed. These results indicate that the textured tool is applicable for the DLC coated tool.
Chips are often jammed in the interface between the spindle and the tool holder in ATC with taper and face fitting system such as HSK. Run-out of the tool is measured in every tool changing to reduce the machining error caused by the chips jammed. In general, the displacement sensor is placed on the table, because tools of different dimensions are used in the process on a machining center. The setup wastes time to move spindle to the place for run-out measurement, and it incurs the increase in cycle time. Objective of this study is to develop the short-time detection method for the chip jamming happened in ATC. Mounting displacement sensor on the spindle housing, reciprocal displacement of the flange of the tool holder is monitored without moving the spindle to the place for run-out measurement. Then, both radial and axial displacement is measured for improving sensitivity of the eddy current sensor. In addition, the signal processing method is considered for automatic detection. It is confirmed that measuring sensitivity is improved and that the signal can be processed in wide range of spindle speed. By this method, it is possible to detect chip jamming during the spindle moves to machining position after ATC, and the cycle time is not increased.
Optical encoders are widely used in precision positioning machines today. However its resolution is limited by the optical grating pitch. In order to achieve a resolution of under 1nm, we have to use very small pitch grating which is made by special tools such as a hologram machine. This high resolution grating increases the encoder cost and complicates the installation procedure. Then this paper introduces a new low-cost measurement system with improved sensor stability and easy installation, using scanning metrology principles, which is a combination of interference laser encoder optics and small optical scanner. High frequency scanning of interference laser on moving scale creates harmonic signals which contain position information. High bandwidth phase detection logic using PLL developed by NanoWave Inc. decodes the signals to produce position information up to 7.6pm resolution from 4 micro meter pitch grating scale. The entire signal processing logic is implemented on one FPGA chip, which also keeps the cost of the system low. Furthermore, its relatively long grating pitch also realizes great robustness and provides easy installation in high precision sensing unit.
This study developed an efficient order picking scheduling method in a large-scale logistic center. The proposed method consists of two solutions, one focuses on the picking tour navigation problem and another focuses on the order batch generation problem. The local clustering organization (LCO) algorithm is applied to determine the picking tour navigation. Then, the heuristic batch generation algorithm is introduced based on the product order similarity. Numerical experiments proved that the proposed method improved almost 16% of the order picking efficiency, comparing with the conventional method.