This invention relates to a boring machine having an improved boring spindle in which a pair of swing arms are rotated in a radial direction of the spindle, and a pair of rams are assembled in the respective swing arms to be movable in the radial direction.
In a known boring machine for cutting and working the inner surface of a workpiece, a cutter for cutting the workpiece is attached to the front end of a boring spindle and it is therefore necessary to change the cutter with another one every time when an operator wants to cut the workpiece by varying the radius of the cutter. Moreover, in a case where it is required to cut a splittable casing having a small inner diameter, two pieces of the splittable casing are independently worked and assembled into the casing after the working, so that in this case, when they are assembled, they may not be perfectly concentric in some case, thus degrading the working efficiency.