Stabilizing of Bolt Fastening Force by Using Ultrasonic Vibration

2007 Fiscal Year Final Research Report Summary

• Project/Area Number: 18560139
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Design engineering/Machine functional elements/Tribology
• Research Institution: Kumamoto University
• Principal Investigator: MORI Kazuya Kumamoto University, Graduate School of Technology, Professor (50190989)
• Co-Investigator(Kenkyū-buntansha): TORIGOE Ippei Kumamoto University, Graduate School of Technology, Professor (40134663) ; IWAMOTO Tatsuya Ariake National College of Technology, 機械工学科, 助教 (20390528)
• Project Period (FY): 2006 – 2007
• Keywords: Thread / Ultrasonic / Fastening Force / Stabilizing / Torque Method

Research Abstract

A method of stabilizing bolt-fastening force by using ultrasonic vibration has been developed. Applying ultrasonic vibration on the head of a bolt the distribution of the friction torque is decreased. To excite ultrasonic vibration a bolt Langevin transducer and a layered ceramic actuator are used.
The most suitable vibration condition has been investigated by the Finite Element Method. The suitable frequency is 70 kHz for M6 thread. (The frequency depends on the geometry of the fastening machine.)
Fastening tests for two conditions have been performed ; (1) Ultrasonic vibration, (2) No vibration. The number of test is fifty, respectively. The range of the fastening torque error is set under 5 %.
According to the results, the average fastening force is 5229 N for the condition oil free. The standard deviation of the fastening force is 454 N.