Yohei Kurabe

Application of friction stir welding for several plastic materials

Application of friction stir welding (FSW) known as a low heat input process to plastic materials was studied. Several plastic materials such as high density polyethylene (HDPE), polyamide 6 (PA6) and polyvinyl chloride (PVC) were selected in order to investigate effect of difference in physical properties of the materials on weldable condition and joining strength. The revolution pitch for the weldable condition in each material increased with decreasing of melt viscosity. Moreover, traverse speed in the weldable conditions of the plastic materials was lower compared with that of metallic material, such as aluminum alloys. Stir zone showed lower hardness value compared to the base material and the hardness reduction ratio depended on the materials. In the each plastic material, joining strength increased with decrease of the revolution pitch. Voids formed at the retreating side and played as a fracture origin. Therefore, it is considered that the joining strength depends on both the degradation of mechanical property and the voids formed at the welded area. The maximum joint efficiency of HDPE, PVC and PA6 were about 70%, 45% and 35%, respectively.

Cutting of a Thick Glass Plate by Using Hot Wire

A thick glass plate was cut by using hot wire. Crack growing was stopped when wire temperature was low. Ligament length decreased with increase in temperature of hot wire and full-cutting was achieved at the temperature of 650°C. The center region in the thickness direction seemed to propagate earlier compared to surfaces regions when the crack propagation was stopped. Finite element thermal stress analysis was carried out. According to distribution of thermal stress inside a glass plate, higher stress was generated in the bottom region at the beginning of the process but occurred in the center region in the later stage as matching with the experimental result.

Joining process and strength in PVC friction stir spot welding with fabricating composite material at welding area

Abstract In order to improve the strength of FSSWed PVC joints, SiC particles were compounded into the welded region at the same time as the welding process. The joining process and its effect on strength of FSSWed PVC joints were investigated in a joining experiment with a PVC plate having a different guide hole diameter for filling the SiC particles. In the case of the specimen compounded with SiC particles with guide hole diameter of 8 mm, SiC particles could be dispersed uniformly in the welded area. In the specimens with guide hole diameters of 5 and 2 mm, dispersion of SiC particles was not observed inside of the welded area. Degradation and increase in local mechanical property was significantly observed at edge of the keyhole and inside the welded area, respectively, in the specimen with a guide hole diameter of 8 mm. The width of welded area increased with increasing guide hole diameter. The joining strength was improved by fabricating composite material in the welded region. The strength increased with increasing guide hole diameter. It is considered that joining strength was significantly affected by the width of the welded area. According to temperature distribution and observation of material flow using a high speed camera, contact between the welding tool and SiC particles before plunging into a lower sheet induced increasing heat input during the process and resulted in promoting the friction stirring. Therefore, it is considered that change in guide hole diameter leads to change in contact area between welding tool and SiC particles and also change in width of the welding area resulting in change in the joining strength.

Influence of Reinforcement Particle Sizes on the Joining Strength of the FSSWed PVC Joint Compounded SiC Particle in Welded Area

In Order to Improve the Joining Strength of Friction Stir Spot Welded PVC Joint, Sic Particle was Compounded by the Stirring in the Welding Process. the Influence of Sic Particle Sizes on the Joining Strength was Investigated in this Study. in Case of the Specimen Compounded Sic Particle with Size of 14.6μm, Heat Generated during the Process Significantly Increased and Resulted in Increasing Width of Welded Region. however, According to Result of Hardness Test, Excessive Heat Generated during the Process Led to Degradation of Mechanical Property of the Welded Area in the Specimen Compounded Sic Particle with Size of 14.6μm. on the other Hand, in Case of the Specimen Compounded Sic Particle with Size of 6.5μm, Width of Welded Area was Smaller than that of the Specimen Compounded Sic Particle with Size of 14.6μm and was Similar as that of the Specimen Compounded Sic Particle with Size of 0.5μm. it was Observed that Hardness of the Welded Area was Uniformly Higher in the Joint Compounded Sic Particle with Size of 6.5μm. Specimen Compounded Sic Particle with Size of 6.5μm Showed the Highest Strength among the Joints Tested. it is Considered that the Joining Strength was Affected by both Width and Mechanical Property of the Welded Area.