Investigation of Chip Deformation and Breaking with a Staggered Teeth BTA Tool in Deep Hole Drilling

Abstract

The problem of chip breaking and evacuation is the key point of staggered teeth boring and trepanning association (BTA) drilling. The factors that influence chip breaking with staggered teeth BTA deep hole drilling are analyzed by using the chip bending deformation mechanism for chip formation and flow through the rake face and chip breaker. This study investigated the distribution and variation of chip deformation and breaking along drilling conditions, with respect to drilling radius, drilling process parameters, tool wear, and chip breaker geometric parameters. The results show that the tool-chip contact length is about 1.65 times the chip thickness in staggered teeth BTA drilling. The cutting radius of the teeth has a considerable influence on the chip thickness. Compared with the drilling speed, the feed has a greater impact on chip deformation and breaking, and the chip thickness and strain increase with increased feed. Increased drilling depth and tooth wear aggravates the friction state between the chip and the rake face, augments chip thickness and tool-chip contact length, and increases the chip’s strain increment. As the width of chip breaker decreases and the height increases, the chip strain increases and the breaking conditions are improved.

Keywords

• deep hole drilling
• staggered teeth BTA drill
• chip thickness
• tool-chip contact length
• chip breaker