Development of a force sensing drill holder for fine drilling

✍ Scribed by T. Oketani; Y. Mase; Y. Nishigaki; N. Sase; H. Fujii

• Publisher: Elsevier Science
• Year: 1996
• Tongue: English
• Weight: 523 KB
• Volume: 56
• Category: Article
• ISSN: 0924-0136
• DOI: 10.1016/0924-0136(95)01870-0

✦ Synopsis

The authors developed a new drill holder which is able to sense excessive thrust and/or torque on a drill and to pull the drill back before it breaks. The holder has two sets of tongues, the relative distance of which varies mechanically when excessive force is applied to the drill. When a predesignated distance is exceeded, a signal is sent to the controller, which stops drill feeding and pulls the drill back. The thresholds of thrust and torque can be adjusted independently. The structure is very simple and small and there is no electrical device in the holder. A performance test was conducted using a drill lmm in diameter and spindle speeds in the range: 3,000 -12,000rpm. The following results were obtained. (1) The time period necessary for withdrawing the drill after sensing an unusual cutting force was about 10ms. This duration was found to be short enough for withdrawal of high speed steel drills without breakage. (2) Simplicity of design and no breakage indicate a high degree of reliability. (3) The life expectancy of drills and the machining costs are greatly improved by usilig this holder.