连续驱动摩擦焊动态扭矩检测的新方法──VCMM法

On Measuring Dynamic Torque Acting on Workpiece in Continuous-Drive Friction Welding

连续驱动摩擦焊动态扭矩检测的新方法──ＶＣＭＭ法刘金合，罗键连续驱动摩擦焊扭矩是一个重要的工艺参数。摩擦焊扭矩是动态扭矩，具有时变性、速变性以及变化范围大等特点。现有的检测摩擦焊扭矩的方法均有一定的局限性’‘－’‘，本文提出了通过驱动主电机定子电压和...

In P. R. China's continuous -drive friction welding, we need increasingly to determine accurately the instantaneous dynamic torque acting on workpiece.This requires synchronously measuring the magnitude and phase of main-motor voltage and those of its current.Only in recent years, have the advancement in world micro-processor technology made such synchronous measurements possible.We now propose a convenient,precise, reliable and anti jamming method for measuring such dynamic torque,preliminarily shown to be satisfactory by experiments and believed to be the first such method proposed in China.In the process of continuous-drive friction welding, friction torque T(t)and heating power Pheat are usually given by where μ(r,t )-friction coefficientP(r,t)-friction pressureR-radius of workpiecer-the distance of a point on friction surface from workpiece axis n(t)-the rotation rate of workpiece Because n(t)is independent of r, soPheat(t)T(t)By means of synchronously measuring the stator voltage, the stator current and the rotation rate of workpiece,the input power of main-motor can be calculated on computer. Fig. 1 shows the variations of measured voltage,measured current and calculated friction torque with time.The measured voltage was the effective value for a cycle consisting of 200 measurement points,and the measured current was the effective value for the same cycle.The experimental conditions were as follows:material: 65Mn steel diameter of workpiece: Φ27mmfriction pressure:1.76 MPa friction time: 6 sforging pressure:3.43 MPa dwell time:8 sThe error analysis indicates that the error of measurement is less than 5%.