Evaluation of Thrust Force and Cutting Torque in Reaming
Reaming is a process that is widely used in industry with very little theoretical modelling being carried out. In this paper the cutting action of the reaming operation is presented by explaining the thrust and torque involved. A model based on an orthogo
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R. Narimani and P. Mathew University of New South Wales, Sydney, Australia
KEYWORDS:
Reaming, Metal Cutting, Thrust and Torque, Modelling
ABSTRACT: Reaming is a process that is widely used in industry with very little theoretical modelling being carried out. In this paper the cutting action of the reaming operation is presented by explaining the thrust and torque involved. A model based on an orthogonal theory of machining and variable flow stress is presented in order to predict the thrust and torque involved in the cutting process. A comparison of the predicted and experimental results give good correlation and thus indicates that the procedure used is viable.
1.0 INTRODUCTION Reaming is an internal machining operation which is normally performed after drilling to produce holes with better surface finish and high dimensional accuracy. A reamer consists of two major parts. The first part is the chamfer length for material removal and the second part, the helical flute section, carries out the sizing operation of the hole. During a reaming operation the chamfer will first remove the excess material left from the drilling operation which is then followed by the helical flutes which size the hole precisely and produce a good surface finish. In analysing the thrust force and cutting torque in a reaming operation the first step will consider the action of the chamfer length. To study the forces acting on the chamfer, it is necessary to investigate the cutting action of a single tooth in the reamer (Figure 1). The investigation of the single tooth showed that the cutting edge represented a Published in: E. Kuljanic (Ed.) Advanced Manufacturing Systems and Technology, CISM Courses and Lectures No. 372, Springer Verlag, Wien New York, 1996.
R. Narimani and Ph. Mathew
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Helical Part
Chamfer Length
SectionAA
Figure 1: Reamer geometry and cutting forces similar geometry to a single point turning tool involved in an external turning operation. Thus it is expected that the reaming process can be modelled by assuming that a single tooth is a single point tool with zero or low normal rake angle, low inclination angle and a negative side cutting edge angle (chamfer angle). Using this assumption then it is possible to use a predictive theory of machining developed by Oxley and his co-workers [1] to predict the thrust and torque in reaming. In the following sections, an experimental investigation of the reaming process is given followed by a brief description of the machining theory and the extension to the reaming operation. The experimental results are compared with the predicted results to verify the theoretical development. Finally conclusions are presented. 2.0
INITIAL THRUST AND TORQUE OBSERVATIONS
An experimental investigation was carried out to observe the thrust, the torque and the chip formation during the reaming operation. The experiments involved reamer sizes of cj)lO.Omm to cj)16.0mm with varying drill sizes (cj)9.5mm to cj)15.5mm) for each reamer. A total of 18 experimental observations were obtained f
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