DESIGN AND MANUFACTURE OF A HYDRAULIC EXPANDING MANDREL

Abstract

The present scenario in the mechanical manufacturing industries is, the conventional machine tools are being given a go by and more and more small as well as medium scale industries have switched over to CNC Machine tools. The CNC Machine tools basically with their higher accuracies and higher rates of production need to utilize more precision component location and clamping systems. Our Prime Ministers recent policy guideline “MAKE IN INDIA” makes it all the more important that in order to compete with international manufacturers, the manufacturing Industry should achieve component location and clamping elements of much higher accuracy. The present work involves the Design and Manufacture of a Hydraulic Expansion Mandrel. Hydraulic Expansion Mandrels and chucks are high precision work or tool holding devices for true running of work piece for further machining operations, or inspection of concentricity. In case of tool holding, they increase the tool life by about 15 to 20% due to true running. Typically, the run out is less than 0.005mm Total Indicator Reading (TIR) in expanded condition. The Hydraulic medium used is a solid Hydro-Plastic Jelly and the mandrel expands with 1 or 2 rotations of a set screw. No external power pack is required. The Hydraulic Medium being solid, the leakages are very low. If the length to diameter ratio is in the range of 2 to 3, very high clamping forces can also be achieved. As a sample case, a 32mm diameter Hydraulic Expanding Mandrel is designed and manufactured to locate and clamp components with a bore size of 32.00H7.