Design and Development of Combination Tool for Drilling and Tapping Operation on PVC

Abstract

Form or friction drilling is becoming popular due to its ability to quickly form the hole with bushing on the sheet material. The formed hole is to be tapped with form tap, and thus, tapped holes on the sheet materials are used in sheet metal working processes. This process requires two separate operations of form drilling and form tapping and consumes extra time causing more cost of production. This paper proposes the design and development of combination tool, made of high-speed steel (M2) tool which combines the friction drilling and form tapping operation in a single step. The main objective of designing the combination tool is to minimize the operation time and cost of production as both operations can be performed on the same machine using a single tool. The combination tool have been designed keeping in mind polymeric sheet material and the geometry of form section and ta section decided according to the requirement. The two sections of combination tool, viz. form section and tap section used to carry out the operation in that sequence. Form section of combination tool has the geometry vis-a-vis friction drilling tool. The rotating conical tool when contacts the work piece generates the frictional heat resulting in softening of work piece material. Further advancement of tool into the work piece leads to plastic flow of material along the direction of feed which reproduces the cylindrical hole resembling cylindrical portion of form section. Tap section which is located just above the form section carries out the second sequence of operation, i. e., form tapping. Process involves the reproduction of threaded profile on the drilled holes which completes the cycle of forming and tapping the holes on the sheet materials.