| 摘要 |
PURPOSE:To precisely detect the shift between a screw hole and a workpiece in an automatic screw tightening device provided with a detector for the relative positions of a screw tightening machine and the screw hole, by symmetrically arranging a light-emiting sensor and a light receiving sensor which are directed to the center axis of the secrew hole. CONSTITUTION:A light emitting sensor 3-a and a light receiving sensor 3b are attached respectively to screw holding devices 14-a, 14-b such that the light from the light emitting sensor 3-a reaches the light receiving sensor 3-b after being reflected by a workpiece 13. If a driver part 6, a screw 1 and a screw hole 2 are aligned with the same axis, the light is reflected by the inside of the hole, and therefore, does not reach the light receiving sensor 3-b. If the screw hole is shifted, the light reaches the light receiving sensor 3-b after being reflected by the workpiece 13, and therefore, a signal from the light receiving sensor 3-b is used to judge between the enabling and disabling of screw-tightening in the non- contact condition of the screw 1 with the workpiece 13. |
