Search

Laser quenching is a partial quenching method that significantly reduces deformation associated with heat treatment compared to conventional methods such as furnace quenching and induction quenching. However, thin parts such as brake disk and miniature-guide rail are subject to large deformation even by laser quenching. To expand the laser quenching applications, we proposed “dummy irradiation method” to complete heat treatment and deformation correction only by laser irradiation. Although the effectiveness of this method has been confirmed in our previous study, more detailed studies on the deformation of thin steel plate caused by laser irradiation are necessary to achieve highly accurate correction by dummy irradiation method. Therefore, laser irradiation experiments were conducted under various laser powers on three types of S50C plates with thicknesses of 2.5 mm, 3.0 mm and 3.5 mm, and the detailed deformation behaviors and the mechanism of the deformations were investigated. By the laser irradiation, the downward convex deformation (positive deformation) was caused in the direction perpendicular to the laser scanning direction, regardless of the laser power or plate thickness. In the laser scanning direction, both positive and negative deformations occurred depending on the laser power. Positive deformation occurred at low laser power and negative occurred at high laser power. Positive and negative deformations occurred at different times during the laser irradiation process: the positive deformations occurred during or immediately after the laser irradiation, while the negative occurred during the cooling process. It was found that the negative deformation in the laser scanning direction that occurs at high laser power could be related to the bending moment generated by the positive deformation in the direction perpendicular to laser scanning. From this result, it was considered that the plate width would affect the deformation caused by laser quenching. In order to correct the deformation by dummy irradiation, it is necessary to consider the plate width of the object as well as the laser irradiation conditions such as laser power and scanning speed.

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, 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.