Patent ID: 9649698
Date: 2017-05-16
CPC Classifications: B23B,Y10T

Claim:
1. A tool clamping device for a machine tool, the tool clamping device comprising: a main shaft; a spring provided in the main shaft; a draw bar inserted into the main shaft so as to be opposed to the main shaft with the spring interposed between the main shaft and the draw bar, wherein the draw bar is provided with a concave portion on an end of the draw bar, and wherein the draw bar is movable in an axial direction of the main shaft; a steel ball provided around the end of the draw bar, wherein the steel ball is movable in a radial direction of the main shaft in response to a movement of the draw bar; and a main-shaft-side inclined surface defined by an impression on an inner wall of the main shaft, at a position where the steel ball is movable inward and outward in the radial direction; wherein a tool holder provided with a pull stud having a tool-holder-side inclined surface is attachable to the end of the draw bar; when the tool holder is attached to the end of the draw bar, the main-shaft-side inclined surface and the tool-holder-side inclined surface compose a magnification mechanism with the steel ball interposed therebetween, along the axial direction, the inner wall of the main shaft has first and second sections connected to opposite sides of the impression, and the impression extends outward, in the radial direction, from both the first and second sections of the inner wall of the main shaft.