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In the present report, we focused on high reduction ratio hypoid gear with a three-tooth pinion and its meshing performance. First, we monitored the tooth surface temperature in meshing teeth, based on combined image from temperature images with a high-speed-camera thermography, and compared it with tooth contact image with a red paint. Moreover, we proposed a predicting method of tooth contact area from a combined temperature image on the tooth surface. Second, we estimated its real contact ratio based on measuring the tooth root stresses at the toe, middle and heel positions. Third, we measured the meshing transmission error (MTE) between the gear and the pinion, and the rotational acceleration at the gear outer in meshing teeth. As a result, it could be seen that the real contact ratio affected tooth surface temperature and MTE. Regarding a high reduction ratio hypoid gear, the deformation at the gear rim also affected the dynamic vibration in meshing gear and pinion teeth.

This paper examines the machining accuracy when simultaneously machining pilot holes and threads, and the machining accuracy when machining threads after pilot hole drilling. To verify them, cutting forces were measured in the tool rotation coordinate system using a wireless holder. To examine the influence of the machining area of the tool bottom edge machining the pilot hole, three patterns of pilot hole diameters (φ0 mm, 7.0 mm, and 8.5 mm) were used. The results showed that when the pilot hole diameter is φ0 mm, the cutting force in the plane direction does not increase significantly compared to the case with a pilot hole due to the offset effect of the cutting forces generated by the facing cutting edges when machining the bottom edge. Therefore, if chip entrapment can be prevented, it is highly possible to omit the pilot hole, improve machining efficiency, and maintain machining accuracy. It was also found that tool vibration could be reduced. However, when the pilot hole diameter is Φ0, the load in the tool axis direction increases. Therefore, it was also found that machine rigidity and tool life must be considered due to the increased load during machining. These results are summarized in this paper.

In this study, we are attempting to create self-adhesive moldings made entirely from bamboo fibers extracted by a machining center in order to solve global environmental problems and the destruction of ecosystems caused by bamboo. However, the mechanical properties of the moldings are still insufficient. In the present report, we clarify the molding conditions that can improve the mechanical properties of the molded plates. First, the cause of fracture of the plates during tensile testing was investigated. As a result, it was considered that the cause was the fracture at the adhesion area or fiber withdrawal. To enhance the adhesive action, we focused on lignin, an adhesive component in bamboo, and its flow process during molding. We investigated the effects of in-mold temperature and pressure and molding time on the thermal flow of lignin. As a result, it was found that the thermal flow of lignin progressed and the mechanical properties improved as the time and pressure were increased. Therefore, we attempted to determine the molding conditions that maximize the tensile strength of the moldings by referring to a manufacturing process model for fiber-reinforced composites. Five specimens were fabricated, and a tensile strength of 32.37 MPa was achieved with a standard deviation of 0.55 MPa, which is equivalent to that of general-purpose plastics.

We have developed a small size and high strength spiral bevel gear fabricated by five-axis controlled machining center. In the present report, we propose a novel spiral bevel gear with the rib at the end of face width to reinforce the tooth bending strength, which is machined with a ball-nose end-mill tool. We investigate the influence of the triangular rib on the bending stress both at the tooth root and around the rib and tooth deflection based on 1DCAE model, and demonstrate the effect of rib reinforcement at the proposed spiral bevel gear. Moreover, we compare the calculated stresses by 1DCAE with experimental ones from fabricated spiral bevel gear. As a result, a novel guideline is found to develop the small size and high strength spiral bevel gear with the rib at the end of face width from a view of rib shape.

In recent years, the development of technologies for "connected factories" based on the Internet of Things (IoT) has become important, and industrial robots are required to operate autonomously based on sensing technologies and their data. In this paper, we focused on the polishing work with a cooperative robot, and discussed a method to integrate the technology of the developed wireless vibration monitoring system with the internal information of the servo. In particular, we attempted to construct a novel finishing system that utilizes the internal information of the force sensor installed in the base of the cooperative robot not only to detect human contact but also to improve the accuracy of machining. We estimated the rough-endmilling state from the in-process monitoring the vibration with a wireless tool holder system and the internal information of the servo obtained during endmilling operation, and also integrated the finishing process using the newly developed system considering rough endmilling information with a cooperative robot.

The vibration generated at the contact point between a tool blade and a machined surface during cutting significantly influences the generation mechanism of regenerated chatter vibration. However, it is difficult to measure the vibrations generated at this contact point. In our previous research, we focused on the chatter mark formed on a machined surface owing to the chatter vibration during cutting, and analyzed the periodicity of the pattern using a two-dimensional discrete Fourier transform. Furthermore, we proposed a method for inversely analyzing the chatter vibration information generated at the contact point during cutting from the periodicity of the chatter mark, and demonstrated its effectiveness. The proposed method is based on the formation mechanism of the chatter mark estimated from the geometrical relationship between the tool blade and the machined surface, and the validity of this formation mechanism has not been directly investigated. In this research, the movement of the tool blade during cutting was reproduced based on the vibration displacement of the tool shank measured in the cutting experiment. A voxel model cutting simulation was then performed using the reproduced tool blade movement, and the chatter mark was reproduced in the simulation. By comparing this reproduced pattern with the chatter mark obtained by actual processing, the validity of the inverse-analysis model proposed was verified more directly than the previous research.

We attempt to construct a novel automation technology based on the hammering task and its sound feedback process with an industrial humanoid robot equipped with an integrated system of vision, sound and dual arm motion. First, we focus on a musical saw to achieve a tuning motion as its basic study because it is considered to be difficult to control a kind of unknown and unclear tool under beginning operation. Second, we discuss its characteristics to develop the tuning motion based on dual arm motion and sound feedback system. Third, we attempt to cooperate on hammering task by right arm and bending task by left arm for the musical saw with estimating its hit sound. As a result, it can be seen that the proposed system using an industrial humanoid robot makes it feasible to achieve sufficient tuning motion for the musical saw such as unknown and unclear tool. Therefore it is demonstrated that the proposed approach is found to be useful to construct the automation technology based on the hammering task and its sound feedback process with an industrial humanoid robot.

In the present report, we attempt to monitor the temperature of Cu direct laser drilling process of multi-layer printed circuit board with a high speed camera based on two color method and to construct a model of its process with a CFD (computational fluid dynamics). We look at the via-hole drilling using a CO2 laser beam for the FR-4 type insulation layer, which made of glass fiber reinforced epoxy resin plastics, as build-up layer. First, we estimate the temperature distribution at the time line of process including the penetration of Cu layer on the surface and the cooling of drilled hole wall after laser drilling. Second, we discuss a CFD model for the drilling process based on finite volume method. As a result, it can be seen that the monitored results is in good agreement with the calculated ones by CFD model.

We suggested a novel method to maintain a machined surface quality of a curved surface shape by synchronous motion between two linear axes and a rotary axis with the five-axis machining center. It was demonstrated that the proposed method made it feasible to prevent a machined error due to the quadrant glitch caused by friction of the ball screw and linear guide of feed drive system by the method. Moreover, in the previous report, we discussed the influence of servo characteristic difference between linear axis and rotary axis on the machined shape error to improve machined surface quality and suggested a method to reduce shape error of machined workpiece with an advanced control. However, we have not discussed the errors that influence the shape with this method and suggested an improved method based on non-machining motion. In the present report, we focused on using this method to develop a motion for cutting a circular shape, including approach path during actual machining. First, we developed a model formula for the shape error based on the predicted causes of error. Second, we validated our model based on NC data from an actual end-mill tool. We then determined the most appropriate processing method by comparing cutting results. The causes of error were identified as a circle radius decrement due to the circular interpolation motion of the two linear axes, relative angle difference between the linear and rotary axes, and eccentricity of the circular interpolation motion of the two linear axes because of the outside approach path of the machining tool. Finally, we confirmed an effect on reducing the shape error of the machined workpiece considering differences in the servo characteristics of the three axes by monitoring the cutting force with a wireless tool holder during machining. The results showed that the proposed method greatly decreased the shape error.

To support the engineer in the selection of drills and their machining parameters, we propose a novel catalog mining system based on data mining techniques applied on drill catalogs by using twice the Fuzzy c-means method along with the Maximum Information Coefficient (MIC). We first perform the clustering algorithm Fuzzy c-means that returns the membership degree of every point to each cluster on the parameters defining a series of tools. We then use the maximum information coefficient (or MIC, index measuring the correlation between two parameters) to find the drill or material properties that have the most influence on the drilling conditions in each of the clusters in order to realize a second clustering that includes the drilling conditions. The Davies-Bouldin index (DBI), which evaluates the dispersion inside the clusters, is used to assess the result of the second clustering and find its optimal parameters. Finally, a multi linear regression is used to find the equations predicting the drilling conditions in each sub-cluster. The mean squared error indicator is used to validate the result of the prediction. A new flexible index based on the membership degree value computed by the Fuzzy c-Means algorithm is proposed to filter the points and clarify the borders of the clusters in order to optimize the data used in the regression.

In this report, we propose a method to analyze the frequency and phase difference of self-excited vibration during cutting by using image analysis for the photographed image of the machined surface by end milling. It is widely known that, when chatter vibration occurs during cutting, periodic patterns, called chatter marks appear on the machined surface. In previous studies, the periodicity of chattering was judged by visual observation, but this reading operation was difficult, and advanced skills were required to obtain stable results. In this study, the periodicity of the chatter mark is analyzed from the frequency spectrum of a two-dimensional discrete Fourier transform. Image analysis of chatter marks by Fourier transform facilitates the evaluation of the periodicity from the entire image data, so it enables very robust frequency analysis compared to conventional methods. The machined surface images necessary for chatter mark analysis were acquired using a commercially available digital camera and machine tool. To verify the effectiveness of the proposed method, chattering vibration generated during side cutting with the end mill was estimated and compared by the image analysis of the chatter mark and vibration analysis with a displacement sensor. The values of both analysis results are close, and it is found that the proposed method is an effective method for chatter vibration analysis.

We attempt to construct a novel technology development utilizing big data such as Deep Learning in the manufacturing industry. Especially, we look at the data mining method and the tool catalog as a useful big data base which is updated by tool makers because it is easy for CAD/CAM engineers and machine tool operators to obtain it in the manufacturing fields. In the present report, we proposed the visualization and consideration of cutting condition determination process based on a decision tree method which is one type of statistical analysis method for radius-endmill data base. We also developed a cutting condition prediction system with a random forest which is a type of machine learning method applying a decision tree. Moreover, we performed a case study in endmilling under deriving cutting conditions by the proposed method, which is an unknown and expanded cutting condition based on tool catalog data base. As a result, it is demonstrated that the support based on machine learning is found to be effective to select a cutting condition including an unknown cutting condition in tool catalog data base.

In the present report, we attempted to construct a useful monitoring method to control laser via-hole drilling process of multi-layer printed wiring boards with a high speed video camera.Cu direct laser drilling was performed for the FR-4 type insulation layer, which made of glass fiber reinforced epoxy resin plastics, with a CO2 laser beam. First, we discussed the influence of laser irradiating conditions on the drilled via-hole quality based on estimating the visible video camera images. Second, we focused on two-color method to visualize the temperature distribution in monitoring image. As a result, the high speed video monitoring and the temperature visualization in video image are found to be effective to control the via-hole quality in laser processing.

We have developed a small size and high strength spiral bevel gear fabricated by five axis controlled machining center. In the present report, we propose a novel spiral bevel gear with the rib at the end of face width to reinforce the tooth bending strength, which is machined with a ball-nose end-mill tool. We investigate the influence of the rib shape on the bending stress at the tooth root based on 1D-CAE model and demonstrate the effect of rib reinforcement at the proposed spiral bevel gear. As a result, a novel guideline is found to design the small size and high strength spiral bevel gear with the rib at the end of face width from a view of rib shape.

Nowadays, a monitoring technology has attracted attention in the factory automation fields regarding IoT (Internet of Things). However, it is difficult to monitor the process information from a round tool during rotating operation in machine tools. We therefore develop a novel tool holder equipped with a wireless communication function to monitor tool temperature and vibration. In the present report, we attempt to measure the inner temperature in drill tool and investigate the influence of feed rate and cutting speed on it. Moreover, we attempt to measure the tool vibrations in the rotational and radial direction in countersinking process. As a result, we demonstrated that the developed method with a wireless system is effective to estimate the tool temperature in drilling processes and the tool vibration in countersinking processes.

A planetary gear train (PGT) is one of the most important components in the hybrid and electric vehicles owing to its high torque-to-weight ratio, light weight, and compactness. But transmission mechanism is still unclear due to structural complexity. Planet gears make PGT complex because of its motion (simultaneous rotation and revolution) and different contact ratio, or meshing stiffness between internal meshing (ring-planet) and external meshing (sun-planet). Although many experimental studies about PGT’s steady condition had been conducted all over the world, no studies have proved motion of planet gear experimentally. In this paper, planet gear instant center of rotation (ICR) is found out based on its velocity distribution and it was proved with direct motion observation on planet gear motion by high speed monitoring. ICR is expected to be effective to estimate meshing transmission errors (MTE) with its feature like light lever. MTEs in a PGT were also discussed based on the fluctuation of trace of ICR, or centrode.

There have been many reports dealing with the motion accuracy of a five-axis controlled machining center. However, there have been few reports dealing with a synchronous accuracy between the spindle rotation and the feed driving motion. In the present report, we propose a novel method to control the cutting trace shape on machined surface in radius end milling, focusing on high repeatability of period in a fixed cycle feed motion to keep a synchronous motion between the spindle rotation and the feed driving motion. Moreover, we attempt to estimate the quality of machined surface with a proposed method for radius end milling of hardened die steel. As a result, a proposed machining method is found to be effective to improve the machined surface quality for a finishing process.

The purpose of this study is to construct the automation technology based on the hammering task and its sound feedback with an industrial humanoid robot equipped with an integrated system of vision, sound and dual arm motion. First, we discuss a suitable flexible rubber stick to achieve the hammering task and developed the acoustic recognition system based on its hit sounds. Second, we confirm that the developed system is sufficient to investigate the task playing the glockenspiel, and also discuss the characteristics of motion based on dual arm motion. Third, we attempt to cooperate with hammering the bottle and pouring liquid into it based on estimating its hit sound. As a result, it can be seen that the proposed system using an industrial humanoid robot achieves sufficient motion accuracy. Therefore it is demonstrated that the proposed approach is found to be effective to construct the automation technology based on the hammering task and its sound feedback with an industrial humanoid robot.

Recently, the miniaturization and multi-functionalization of electronic equipment have been demanded due to developments in IT. Therefore, the miniaturization and densification of the semiconductor package printed wiring boards (PWBs) have been more demanded. For the realization, the miniaturization of PWBs and fabrication of highly dense electrical circuit layers are also demanded. As a result, problems such as broken drill by the increase in aspect ratio and heat damage around the drilled hole are occurred in micro-drilling process of the PWB. A step feed drilling is considered to be effective as a solution to those problems However, it needs a high-speed reciprocating movement in short stroke to keep a drilling efficiency, and then causes residual vibration on machine tool table. In the present report, we propose a novel machine tool equipped with a counter balance mechanism using a left and right lead ball screw. This mechanism consists of a balance mass that moves in the Z-axis direction corresponding to the spindle movement to cancel a vibration force in linear direction at reciprocating movement. We construct a test stand to estimate the reducing effect of vibration force and to mode it. Moreover, we confirm the improving effect in high speed micro-drilling process with a proposed machine tool.

Recently, a novel manufacturing technology has spread out with a five-axis machining center, which is controlled by three linear axes and two rotary axes, because the synchronous control technologies make it feasible agilely to create a three-dimensional and complicated surface such as propellers and hypoid gears using it. By making use of the characteristics, a method to maintain a machined surface quality of a curved surface shape by synchronous motion between two linear axes and a rotary axis with the five-axis machining center was suggested because it is difficult for a three-axis machining center to accomplish that. Moreover, it was demonstrated that a proposed method made it feasible to prevent a machined error due to the quadrant glitch caused by friction of the ball screw and linear guide of feed drive system. However, we have not discussed the influence of servo characteristic difference between linear axis and rotary axis on the machined shape error by this method. In the present report, we aimed at maintaining feed speed vector at milling point by controlling two linear axes and a rotary axis with a five-axis machining center, to improve machined surface quality and suggested a method to reduce shape error of machined workpiece considering differences of three axes's servo characteristics with an advanced control. As the results, it could be seen that shape error greatly decreased based on the proposed method.

The planetary gear train (PGT) is one of the most important components of the new hybrid and electric vehicles due to its high torque-to-weight ratio and to its compact geometry. However, this system generates a lot of vibrations which increase the noise into the vehicles due to its complex geometry and to its various mesh coupled motion. The aim of this study is to construct a novel torsional coupled vibration model based on bond graph method and to understand the planetary gear train motional and modal behavior with a focus on the damping effect of the meshing while taking into account the damping effect of the bearings that connects the system to the shaft. The result from bond graph is in good agreement with observed result, and it can be seen that bond graph is proper enough to simulate dynamic behavior of PGT compared with the results by a traditional equation of motion.

It is well known that a regular chatter mark appears on the machined surface when chatter vibration occurs. There must be an essential information relationship between the chatter mark and the vibration stability. We therefore attempt to construct a novel method to control the chatter vibration of end milling process based on inverse analysis of chatter mark on the machined surface. As a result, it can be seen that chatter vibration occurs not at the frequency of the cutting tool, tool holder, and their coupling but near one, and that the chatter vibration frequency and the regenerative phase can be derived from the surface pattern dimensions, the spindle rotating speed, the helix angle of end mill tooth and the tool diameter. Moreover, we propose an improving method of spindle rotating speed to avoid the chatter vibration in end mill process based on the analyzed frequency and regenerative phase. The proposed method is found to be effective in suppressing chatter vibration without reducing the cutting efficiency because little change of spindle rotating speed is needed.

It is well known that the tooth surface accuracy greatly influences the vibration in gear meshing. The hypoid gear used in automobile differential has a complex shape, and the estimation of the contact conditions is difficult. Therefore we propose a estimating method of the tooth meshing contact conditions with a high response and high speed-camera thermography, based on monitoring the temperature distribution during meshing between the pinion and the gear. In the present report, we attempt to construct to a novel combined infrared image from the temperature data on the extraction line in each continuous shot thermal image, which is composed of temperature distribution on the tooth surface at the same time after tooth meshing. As a result, a proposed infrared image is found to be effective to estimate tooth meshing. Moreover, we develop a predicting method of tooth surface temperature by constructing a heat circuit network model, based on measured temperature on the tooth surface from a combined infrared image. Comparing calculating results with experimental ones, it can be seen that the constructed model is considered to be sufficient accuracy.

Nowadays, a free-form surface, such as molding die surface, is required to be finished by reducing the environmental burden. Therefore, a novel polishing technology is needed with a less abrasive slurry,for the reduction of which a magnetic abrasive finishing method is attracting attention. However, it is well known that a conventional magnetic polishing method is unstable and insufficient to obtain the required surface roughness. In the present paper, we discuss the reasons causing instability in conventional magnetic polishing. We systematically investigate the magnetic pressure distribution characteristics and measure the pressing force distribution of the magnetic brush during machining. Furthermore, to observethe impact of an iron particle shape on the pressing force, we used steel balls (steel-ball brush) and abrasive slurry. Moreover, we compared this brush with a brush that uses iron powder paste (employed in the conventional magnetic polishing method). Thus, we determined the possibility of the wide range control of the pressing force by changing the shape and size of the magnetic material. The setting of the approach conditions should be sufficient because it could deteriorate the shape accuracy through very high pressure.

Recently, printed circuit boards (PCBs) have become multi-layered and complex. It is to provide both multiple functions and to be compact with the development of electronic device such as smartphones. Processing by CO2 laser is frequently used as an effective method of generating blind via holes (BVHs) to connect the circuit layers of multi-layer board. However, there are some kinds of laser drilling methods in this manufacturing field. Among them, Cu direct laser processing is attracted attention, which is a drilling method of both the surface Cu circuit layer and insulation substrate layer at the same time. In the present report, we propose a laser irradiating controlling method based on monitoring the variation of processing luminance when generating the BVH. Especially, we perform the BVH drilling of high heat radiation PCBs, which becomes to be use for high performance electronic devices, and investigate the influence of laser irradiation condition on the drilled hole quality. As a result, the proposed method is found out to be effective to achieve the high BVH quality in the PCB manufacturing fields.

Recently, sustainable materials have attracted attention because of the need to alleviate environmental problems. Bamboo, in particular, has attracted attention as a sustainable material because it has the fastest natural growth rate among various natural materials. A self-bonding fiberboard using high quality bamboo fiber extracted with a machining center has been enabled to be fabricated by hot press forming. Therefore, we propose a sustainable manufacturing system that focuses on bamboo. An environmental impact of our system was evaluated by life cycle assessment (LCA), comparing with a glass fiber reinforced plastic production. Additionally, based on the LCA result, higher efficient fiber extraction process was proposed by an application of in-situ measurement of uninformed bamboo shape with irregularity.

The fixed-abrasive process has been attracting attention as an alternative to the abrasive-free process for finishing surfaces, by virtue of its capacity to improve formability and alleviate environmental problems. Here, we focus on a super-finishing method that uses fine diamond stones. Super-finishing was attempted using low-pressures (< 0.5 MPa) with diamond abrasives averaging less than 3 μm in diameter. We investigated the influence of super-finishing parameters on the surface finish under low-pressure conditions for borosilicate glass. The following conclusions were reached. (1) The surface finish decreased with decreasing stone pressure for ductile cutting. By using a stone pressure of 0.1 MPa, a surface finish of 2 nm Ra with the #12,000 grindstone (mean grain diameter of 0.25 μm) was obtained. (2) Decreasing the mean grain diameter of the abrasive grains decreased the surface finish and could reduce crack formation. (3) A finer surface finish was obtained by increasing the volumetric grain percentage of the grindstone. (4) The maximum crossing angle minimally influenced the surface finish under low-pressure conditions. (5) We found the parameter groove aspect ratio and a method to reduce swell-out height. (6) We successfully demonstrated an evaluation method for polished surfaces and the cutting types. (7) Cracks are reduced on finished surfaces by keeping the depth of cut to less than 100 nm in the case of borosilicate glass.

We propose a non-contact method using infrared ray thermography for measuring gear tooth contact to focus attention on the heat generated on the tooth surface at meshing. First, the radiation performance of the gear tooth surface and the effect of lubrication oil were investigated. Then, the reliability of this technique was evaluated by comparing with the observation result of tooth contact with red lead which is traditional red paint for industrial use. Finally, the possibility of evaluating the meshing transmission error was shown. The results show this technique is effective for monitoring the contact pattern and confirming the surface pressure.

Recently, materials made of natural resources have been gaining attention. In particular, high expectations are placed on bamboo fiber. However, conventional bamboo fiber extraction techniques have problems, primarily involving quality, accuracy, and efficiency. To solve these problems, a new method of obtaining bamboo fibers with a machining center (MC) is proposed. NC programs are designed according to a cutting theory based on a geometrical tool path for cylindrical work. The experimental results verify that fiber shape can be controlled by adjusting the appropriate end-milling conditions with a spiral tool path. The fiber length is influenced by the axial depth of the cut, while the fiber diameter is influenced by the vascular bundle size, which is a component of bamboo. Therefore, considering the direction and size of the bamboo components, the desired bamboo fibers can be obtained with high quality and accuracy using end-milling with an MC.

Recently, increased user demand for quiet vehicle environments has resulted in the need to develop low-noise gears that do not generate noises that are harsh on to the human aural. The principal method for reducing meshing transmission error has been to gear design with as many teeth as possible. However, while these design methods have focused on decreasing gear noise, they have not considered the relationship between gear noise and the background noise of vehicle interiors. In fact, it would appear that no research considering the human aural characteristics associated with gear noise under these conditions has been conducted to date. Furthermore, the problem of gear noise on background noise in vehicle has increased as the use of hybrid engine technology in vehicle has become more pervasive in recent years. The proposed technique for reducing gear noise involves gear design that frequency control of gear noise by changing the number of teeth. The technique described here considers human aural limit and the influence of masking, and how these are affected by the tooth settings of low noise gear. This was achieved by assessing human aural characteristics in the unique acoustic environment of the vehicle interior. Then, the relationship between the number of teeth and the sound pressure level of gear noises was investigated. It was found that the proposed method of varying the number of teeth was effective for designing gears with optimal human aural characteristics.

Planetary gear set is widely used in hybrid vehicle as a power distribution system or in electric vehicle as a high reduction system. Although it has many advantages, its noise and vibration problem has emerged. There have been many reports dealing with two-axis driving or displacement of planet gear under its condition, but we can see no report dealing with about three-axis driving. As first novel point in the present report, three-axis driving is tested on the original test stand. As second novel point in this report, characteristic of instantaneous center of the planet gear is investigated based on mechanism. Planet gear rotates and revolves at the same time during working in three-axis driving condition. Instantaneous center was defined according to velocity distribution of planet gear or superposition of velocity distribution of rotation and that of revolution with simple lumped model. Tangential speed is equal to zero at the instantaneous center, and planet gear rotates around it instantaneously. Instantaneous center moves according to the driving condition or input ratio between two inputs which input from ring gear and carrier. It is very important to consider generated inertia force due to rotation around instantaneous center, to design planetary gear set for three-axis driving. The meshing force between planet gear and ring gear and the meshing force between planet gear and sun gear have same trend and close value but they are not same value, and absolute values of ring-planet meshing force are larger than those of sun-planet meshing force. It is also confirmed that the torques around planet gear are balanced in steady condition, considering both transmission and rotation.

In our research work, we are focusing on bamboo due to its advantages of fast growth, renewability, flexibility, low cost, and high specific strength and stiffness which can be frequently compared with glass fiber. We have proposed a novel hot press fabrication method of binder-free green composite products made of bamboo fibers extracted by end-milling with a machining center. Lignin could serve as a bonding material to make the bamboo fiber self-bonded itself by hot press forming to fabricate our green composite from pure 100% bamboo fiber without any binder materials because its extracted fibers are hardly damaged with a machining center. In our previous studies, we have developed a hot press forming method to fabricate two-dimensional small and simple shape products based on bamboo fiber self-bonded technology. In the present report, we propose a novel two-step hot press forming method based on two kinds of dies to fabricate three-dimensional shape products. Especially, we focus on hemisphere shell shape products because a hemispherical conical cup press forming test is frequently used to estimate the press forming performance of a kind of complex plate products. As a result, the proposed two-step concept of hot press forming is found to be effective to fabricate the three-dimensional shell shape product made of pure 100% bamboo fibers. It can be also seen that a suitable treatment between first and second step is considered important because it aids effective action due to liquid flow performance and the plastic zone of molding material.

Nowadays, infrared thermographic technology has been attracting attention in various industrial fields. We therefore focus on it as a novel method for monitoring surface tool temperature to improve end-milling conditions for difficult-to-cut materials. However, a problem has emerged; it is difficult to measure the tool surface 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 internal temperature under coolant conditions. In the present 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 diameter of 1.0 mm, was used to ensure stable 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 tool internal temperature measured by the wireless tool holder agrees with one calculated by FEM model based on 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.

Nowadays, industrial dual-arm robots have gained attention as novel tools in the factory automation field for anext generation. We therefore focus on them to flexibly control both the linear motion and the rotational motion of a working plate. However, there has been one problem that it is difficult to measure the synchronous accuracy of two rotary axes without high accuracy gyro sensor. Thus, we proposed a novel method to measure the synchronous accuracy of two rotary axes of working plate with a ball, which keeps a ball rolling around a circular path on it by dual-arm cooperative control and demonstrated that a proposed method is effective to estimate its motion of frequency response. In present report, for widening the range of applications, we tried to keep a ball rolling around rhomboid path which is one of polygonal path on working plate by dual-arm cooperative control and to investigate its characteristic.

Recently, with the fabrication of the magic-mirror having the micro C2-continuous surface, it is difficult to hand down magic-mirror fabrication technology, due to downsizing of veteran engineers or even their successors. Therefore, the purpose of this study is to digitalize the magic-mirror fabrication technology using a CNC technology. The novel method which integrate a ball end-milling and magnetic polishing on a conventional machining center is proposed, and a workpiece that was machined by this method is groove cut with straight end-mill from opposite side of its. The micro deformation is occurred by residual stress during the groove cutting. And, in order to evaluate a surface integrity of machined workpiece, a magic-mirror testing which use an artificial sunlight is carried out. In this report, as the results, we signified an optimum ball end-milling condition and a requisite polishing amount, to generate a mirror surface efficiency with the magnetic polishing.

We look at a growing-up force from bamboo to construct a sustainable manufacturing system and have developed the green products made from the sustained reproducible natural materials. Thus, we devised a novel method to extract bamboo fiber which is high-quality with high-accuracy with a machining center. Meanwhile, we also developed the hot press method of bamboo fibers with green mold technology. As a result, the simple shape products could be molded with these technologies as self-bonding bamboo fiber green products. In the present report, we attempt to produce a self-bonding bamboo fiber spur gear, which is a machine element with a complicated shape. First, the molding die is designed and fabricated, and then the molding process is performed to develop a green spur gear. Second, its strength performance is estimated to find out a proper fiber shape. Finally, its driving test is performed to evaluate its dynamic performance. It is demonstrated that the developed bamboo fiber gear is considered to be effective as one of green products.

Recently, infrared imaging technologies have been developing in various industrial fields rapidly. We therefore focus on the infrared ray imagery as a novel method to estimate the gear tooth meshing. In the present report, a high response infrared thermography, which could take a middle infrared ray image of around 4 μm wavelength, was used to investigate the temperature hysteresis on the tooth contact surface of hypoid gear under running conditions. We installed the high reflective mirror of infrared ray at the opposite side of the gear tooth meshing point to obtain the tooth surface images around the entire gear, and estimated the variation o tooth surface temperature at the duration from a tooth meshing to the next tooth meshing. Moreover, using a thermal network model, the modeling of the temperature variation of the gear tooth surface regarding the time is conducted as to predict the temperature after a certain number of rotations. The network model presented in this report is derived from the ones such as Forster network or Cauer network which are based on the concept of thermal capacitance and thermal resistance. This network is investigated to match the actual results on the temperature evolution. Finally, it is clear that the temperature on the tooth surface during a gear rotation can b modeled by first order time delay and the maximum temperature is affected by contact pressure, relative sliding speed between tooth surfaces and average peripheral speed of tooth surface. This proposed method is found to be effective to evaluate the temperature hysteresis on the tooth contact surface of hypoid gear.