Laser peening is a surface treatment method for improving mechanical properties of metal. Conventionally, laser peening has been applied to bulk material and the treatment is conducted under water to prevent expansion of plasma generated by laser abrasion. The method has possibility to be a novel treatment method of thin film metals, however the conventional wet-condition treatment is not suitable for micromachining processes. In this paper, a laser peening under dry condition is proposed and demonstrated. The proposed method use transparent solid material instead of water for medium of laser peening. Glass, sapphire and PET are chosen for the solid medium and dry laser peening using glass shows higher improvement of hardness than that of conventional wet laser peening. The improvement depends on laser power and crack of glass surface which generated by high laser power reduces the peening effect. In addition, air gap between specimen and solid medium is considered. As results, the peening effect is confirmed less than 100μm of the gap thickness and the effect is higher than that of wet laser peening under 20μm.
This paper proposes a novel electrostatic actuator driven by fringe electric field generated between comb-shaped electrodes on a substrate of stator. Ferroelectric teeth of floating mass on the stator are polarized by means of fringe electric field. The mass is laterally moved within the one pitch of the comb-shape electrode thanks to the electrostatic force generated between polarized charge of the tooth and that inside the electrode. Narrow pitch of comb-shaped electrodes is possible, since fluororesin is deposited on the electrode for preventing the discharge between the adjacent electrodes. The narrower pitch increases the electric field even if the applied voltage between two electrodes is rather low, achieving the higher output force. Therefore, the proposed actuator can work at low input voltage. A practical actuator was fabricated, the electrode width and pitch of which were 20 and 80μm, respectively. When the voltage of 300V was applied between the two electrodes, the maximum displacement and force were 20μm and 4mN, respectively. The force per unit area and square of voltage was 0.8N/(kV2·m2), which is not less than those of reported typical capacitive actuators.
Various shaped ball end mills having a large helix angle, multiple flutes and their irregular intervals of the cutting edges are produced and widely used. However, relationships among these variably geometrical components of the tool, cutting forces and tool behavior during milling have not yet been systematically explained. This investigation deals with the tool configuration which makes effect on reducing the movement of the tool axis caused by tool deflection and suppressing chatter vibration. In this report, milling process with ball end mills whose circumferential cutting edges arranged at equal intervals is mainly treated, and cutting forces in the case of one to six circumferential cutting edges are estimated by using a cutting model proposed in previous papers. Then, to clarify the effect of the number of circumferential cutting edges on tool behavior, finite element models of ball end mills having three or four cutting edges are constructed by using geometrical data of the cross-section of a standard-type end mill. Furthermore, the data of cutting forces predicted is applied to these models to analyze the deflection of the tool axis. It is shown that the fluctuation in cutting forces and the tool axis trajectories can be considerably reduced in the case of providing four circumferential cutting edges. In addition, cutting forces of two flutes ball end mill having unequal interval of the cutting edges are estimated, and relationship between interval of the cutting edges and fluctuation of cutting forces is discussed.
This paper proposes a small stackable pneumatic actuator achieving high output density, which is defined (output force)/(volume). The structure of actuator is a cylindrical chamber with inlet and outlet holes, which is stretchable in its axial direction. The chamber is made of flexible elastomer, which is covered by the top and bottom rigid plates made of glass and metal, respectively. The bottom plate has small holes for enhancing adhesion force to the elastomer. In the stacked actuators, the inlet and outlet holes of each chamber are serially connected, which self-assembles tubing. The practical devices were fabricated. When the pneumatic pressure of 40kPa was applied, the displacement and force of single actuator were 20μm and 1N, respectively. Those of three stacked actuator were 70μm and 1.4N, respectively. The output density was as the same order as that of a large sized Mckibben actuator, and it was 0.1 compared with a miniature sized balloon type actuator, which was caused by the smaller force than the design. The force will increase by improving the size and fabrication process of actuator.
This present paper describes some test results about micro-patterning and actuation of conductive polymer (polypyrrole, PPy) for a development of mechanical stimulation device for cultured cells. Pyrrole molecules are selectively electrochemically polymerized with NaDBS to be patterned in dot array using an OFPR template. The fabricated PPy dot has circular truncated cone shape, in which the bottom diameter changed from approximately 10 to 30μm with electric charge. An applied voltage makes the PPy dots expanded or contracted by adsorption or desorption of ions in electrolyte solution. A cyclic change of PPy dot diameter is in-situ observed by a CCD microscope. It is confirmed that the increase of PPy dot diameter corresponds to lateral strain in contraction state. It is found that the maximum change of PPy dot diameter also reaches to 10% at +1V. It is confirmed that the surface of PPy dot has cell adhesiveness after protein coating.
Milling is one of the most important metal cutting processes. If the cutting force could be measured, we can make cutting process optimum, prevent tool breakage, and improve efficiency of process. Especially in the case of using a micro end mill, it is very difficult to identify whether cutting process is good or not. In this paper, a cutting force measurement technique by using image processing was proposed. In the technique, we captured images of end mill by a small CCD camera and mirrors during cutting process from x and y direction to determine deflection of the tool and then estimated cutting force in x-y plane. Finally small cutting force was estimated accurately.
The ball trajectory carries a lot of information for tactics analysis in team sports, so we are interested in automatic ball tracking in American football video. While there are many automatic ball tracking methods, because of holding the ball by one of players and heavy occlusions by the ball holder and other players, tracking ball is difficult in American Football video. Therefore, we calculate the play initial and terminal points using initial formation detection and the concentration degree of each player's direction. After that we connect the ball trajectory or the ball holder's between the play initial and terminal points. We decide which player is the actual ball holder using the team identification result, the distance from play terminal point, and the receiving approach degree by using the information of all players' movement.
Recently, the knee osteoarthritis (OA) patients are increasing, and their qualities of life would be worsen. In order to cope with this, clarifying the mechanism of the knee OA is important, so it is needed to inspect knee joints for understanding of the disease. In this study, the new experiment system was developed to measure knee femur-tibia joint contact pressure distribution during human stand-up motion using knee joint model. Accurate shape knee joint model was fabricated from high polymer material with the use of 3D printer based on human medical images. Knee joint kinematics and joint force during human stand-up motion were reproduced respectively by a robot manipulator and air cylinders. Pressure distribution of knee joint model was measured statically and dynamically, and it was found that medial pressure on the tibial plateau was higher than lateral one, which corresponds with the clinical observation. Therefore, the new proposed method is feasible to investigate knee joints.