Patent ID: 8215214
Filing Date: 2012-07-10
Classification: B23B,B23Q,Y10T

Abstract:
1. A workpiece gripping method for, in a lathe having at least a spindle and tool rests, gripping a cylindrical workpiece by means of an independent chuck attached to an end face of the spindle, the tool rests being disposed on both sides of the axis of the spindle with the axis of the spindle between them in a plane orthogonal to the axis of the spindle and being provided so that they are movable in a direction parallel to the spindle axis and in a direction orthogonal thereto, the workpiece gripping method characterized in that: first, a sandwiching member for centering mounted to each tool rest is arranged so as to be able to face the spindle axis side; then the tool rests are moved so that the sandwiching members and a workpiece loaded into a gripping position at which the workpiece is to be gripped by the independent chuck are brought into a positional relationship that a portion to be machined of the workpiece is positioned between the sandwiching members and the sandwiching members face each other; subsequently, by moving the tool rests in turn or simultaneously, the sandwiching members are moved to their respective centering positions and the portion to be machined of the workpiece is sandwiched and held by the two sandwiching members, the centering position being the position of the sandwiching member when the center position of the portion to be machined of the workpiece coincides with the spindle axis in a state where the portion to be machined of the workpiece is being sandwiched and held by the two sandwiching members; and thereafter the workpiece is gripped by the independent chuck while the portion to be machined of the workpiece remains sandwiched and held by the two sandwiching members.