Clamp shaft used for clamping workpiece with inner spline hole

The utility model relates to a clamp shaft used for clamping a workpiece with an inner spline hole. According to the clamp shaft used for clamping the workpiece with the inner spline hole, a positioning step surface is arranged at one end of the shaft, the shaft is sleeved with the workpiece in a penetrating mode, one end of the workpiece abuts against the positioning step surface, and a tapered surface, corresponding to the inner spline hole of the workpiece, is arranged on the shaft. The clamp shaft used for clamping the workpiece with the inner spline hole has the advantages that a sleeve with a tapered hole corresponding to the tapered surface is selected to be matched with the inner spline hole of the workpiece according to the tapered surface, radial positioning is carried out, the interval between a spindle and the workpiece is eliminated, accuracy is guaranteed, the workpiece is simply clamped through the positioning step surface and a positioning nut, the effects of simple and convenient operation an