Proposal of a Fastening Method for Deformable Plastic Parts and Rigid Metal Parts

Weight reduction is becoming increasingly important to reduce the power consumption of robots. Our ultimate goal is to fabricate practical industrial robot structures using resin 3D printing technology to reduce the robot's weight. In general, 3D printed parts made of resin are soft and deformable; thus, conventional screw fastening does not work well. This paper proposes a method to reduce the stress on a plastic member by inserting a thin-walled metal pipe into a plastic member and subjecting it to the axial force of a screw. The effectiveness of the proposed method was experimentally verified by measuring the thickness of the plastic test specimen and the tightening torque of screws over one month. The maximum torque load test was also conducted to confirm that the fastening force was sufficient for practical use.