Effect of Thermosyphon Limits on Design of A Taper Thermosyphon Drill for Dry Drilling Operation

This paper focused on the effect of thermosyphon limits on the design of a taper thermosyphon drill for dry drilling operation. Although, other methods such as minimum quantity lubrication have been sought but the harmful effects of metal working fluids persist. This study however focuses on the design, fabrication and testing of a thermosyphon drill for eliminating the use of metal working fluids in drilling operations. The methodology included the design of a taper thermosyphon drill, analysis of the thermosyphon drill, manufacturing and testing of the thermosyphon drill. A virtual design and stress analysis of the reversed tapered thermosyphon was done using SolidWorks software. A high speed steel drill bit was manufactured to suit the design requirements of the thermosyphon. The thermosiphon was then fabricated within the machine shop floor using Electric Discharge Machining through method of spark erosion. A reverse tapered thermosyphon was designed to improve the optimal performance of the drill. The reversed tapered thermosyphon specification includes a 20 mm diameter drill, a length of 140 mm and web thickness 7mm, with a taper thermosyphon of 6.48 mm large diameter and 2.5 mm small diameter on a length of 114 mm. The optimal position stress analysis shows that the tapered thermosyphon drill experienced a Von Mises Stress of 38.4 MPa for the cutting distance from the drill tip and 372°C for the optimal temperature. The optimal position stress analysis also showed a Von Mises Stress of 17 MPa for the largest taper diameter and 433°C for the optimal temperature. The thermosyphon drill bit was manufactured and tested against the dry drill and metal working fluid drill bit. The results displayed a reduction in drill bit peak temperatures on the drill bit tip of about 40% for the dry drilling and thermosiphon drilling processes.