Development of Friction Drive Screw with Adjustable Lead Angle Mechanism

两种摩擦传动螺旋机构已在实践中得到应用。一种在圆柱轴和几个径向轴承的外表面之间有滚动接触，另一种在螺旋轴和几个径向轴承的内圈之间有滚动接触。本研究开发了一种新型的导向角可调的摩擦传动螺杆。这种摩擦驱动螺杆机构允许停止、启动、反向和可调速度，而不考虑传动轴速度。前角可调机构由超声波电机和减速器驱动控制。本文报道了我们研制的一种新型导向角可调机构摩擦传动螺杆的设计和特点，并对其工作性能进行了测试。本研究得出的结论总结如下。(1)独特的直线轴承和径向轴承的串联组合使摩擦驱动轴承和传动轴之间的螺旋运动。(2)数值分析了摩擦驱动轴承在传动轴上倾斜前角所需的扭矩。(3)运行试验表明，导向角可调机构可使导向角在-20~20度范围内平稳运动。(4)无论传动轴转速如何，摩擦传动螺丝的其余部分，即导向角为0度都保持不变。(5)在超声波电机的控制下，无论传动轴的速度如何，也可以进行重复往复和加速运动。

Two types of friction drive screw mechanism have been used in practice. One has rolling contacts between a cylindrical shaft and outer surfaces of several radial bearings, and another has rolling contacts between a screw shaft and inner rings of several radial bearings. In this study, a new type of friction drive screw with adjustable lead angle mechanism is developed. This friction drive screw mechanism allows stop, start, reverse and adjustable speed regardless of drive shaft speed. The adjustable lead angle mechanism is driven and controlled by an ultra sonic motor and a reducer. We wish to report on the design and characteristics of a new type of friction drive screw with the adjustable lead angle mechanism which we have developed and of which we have tested the operating performance. Conclusions drawn from the present research are summarized in the following. (1) The unique serial combination of linear and radial bearings makes a screw motion between the friction drive bearing and the drive shaft. (2) Torque required to tilt the lead angle of the friction drive bearing on the drive shaft is numerically analyzed. (3) Operating tests reveal that the adjustable lead angle mechanism allows smooth movement at lead angle ranging from -20 to 20 degree. (4) The rest of friction drive screw, namely a lead angle of 0 degree, is maintained regardless of drive shaft speed. (5) Repeat reciprocating and accelerated motions are also performed by the control of the ultra sonic motor regardless of drive shaft speed.