| 摘要 |
PURPOSE:To improve the tightening accuracy with the control of a rotary driver by determining the relationship between the shaft force of a reference bolt and the axial ultrasonic wave propagation time to measure the shaft force on the basis of the ratio with the length of the actual bolt. CONSTITUTION:An ultrasonic vibrator 26 is fixed on the bottom surface 24 facing the end face 22 of a bolt head 12 and connected to an ultrasonic wave receiver 28. Then, the vibrator 26 converts an electrical signal from the receiver 28 to an ultrasonic wave to transmit it to the end face 22 of the bolt head 12 and receives and converts an echo reflected from the end face 30 of the bolt shaft 14 to an electrical signal to feed it to a receiver 28. On the other hand, a microcomputer 34 with a setter 32 connected thereto is connected to the receiver 28 to control the start and stop of a driving motor 20. This enables the correction of the axial force according to the length of the actual bolt with respect to the reference bolt to assure an accurate tightening to a specified shaft force. |
