Optimal design of BTA deep-hole cutting tools with staggered cutters

Abstract

A concept using an optimization technique to design multi-edge BTA tools with cutters ‘taggered’ on the cutting head is developed. The cutting edges are located on the head so that they cut in a circular pattern over a portion of the hole radius, partly overlapping with each other. In many applications these tools should be superior to the conventional single-edge tools or multi-edge tools with cutters located at 180 degress to each other. When heavy cuts and large hole sizes are attempted with single-edge tools a large resultant force transmitted to the bore wall through the guiding pads causes undue rubbing and wear of the pads. This is followed by heat generation and increased power consumption and deterioration of the cutting edges. The tools with a staggered or zigzag arrangement of the cutters are designed for a predetermined cutting force resultant necessary for the tool guidance, which is controlled by appropriate radial and angular location of the cutters on the cutting head. The cutters of these tools can be combined at will, taking standard carbide inserts or trepanning insets of various grades to satisfy the hardness and toughness requirements, which change according to the increase in cutting speed by radius. The concept also offers more flexibility with regard to space required for chipmouths and chipthroats, resulting in better mass balance as well as the higher rigidity and strength of cutting heads.

The design procedure includes the mathematical model of cutting force components, the optimization and simulation procedure yielding the optimal tool-design parameters which are used for tool layouts. The preliminary tests of the two tool prototypes indicate that these tools are superior to the single-edge tools.