REDESIGN OF “SAFETY RING” WORKPIECE FROM PROTECTION ASSEMBLY OF AN OFFICE CHAIR

The paper presents the redesigning process of a plastic component named “safety ring” that is a part of the protection system of the hydraulic cylinder of an office chair. The main objectives of the redesigning process were to reduce the weight of the workpiece and increase the clamping strength in assembly between “safety ring” and the first segment of the telescopic tube of the hydraulic cylinder protection assembly. After the workpiece was analyzed together with the working conditions, it has been redesigned such that to keep its functional role, as well as the shape and dimensions of the part on which it is mounted (the first segment of the telescopic tube). To validate the concept, the 3D model was first printed and then assembled together with the initial parts of the protection assembly of the hydraulic cylinder, to check its functionality. Because the “safety ring” piece is one obtained by plastic injection molding process, a simulation of the injection process was performed in order to validate the 3D model in terms of the manufacturing process. Using Catia V5R21 software was designed the injection mold for the “safety ring” piece, and with SolidCam 2013 was designed the manufacturing technology for the active plates of the mold. Finaly, the mold active plates were manufactured using Challenger Microcut 2418 vertical milling machine and the new variant of “safety ring” was obtained. Keywords : 3D printing, injection simulation, mold design, mold manufacturing