HORIZONTAL LATHE

PURPOSE: To reduce the fluctuation of machining accuracy caused by the thermal deformation of a lathe having a bed provided with the horizontal Z-direction guide face at the upper face, and a Z-sliding base provided with an X-direction guide face inclined to the front side (worker's side) in relation to the bed upper face. CONSTITUTION: A headstock is formed being divided into a frame part 11 at the lower part, and a bearing part 12 at the upper part. The connected face 13 of the frame part 11 and bearing part 12 is formed into the inclined face parallel with the X-direction guide face of a Z-sliding base. It is desirable to interpose heat insulating means 17, 19 at the connection part 13 of the bearing part 12 and frame part 11 of the headstock. The resistance of heat transfer is generated to the connection part of the frame part 11 and bearing part 12, and the temperature rise of the bearing part 12 is large, while the temperature rise of the frame part 11 is small. A main spindle 14 is displaced in a direction orthogonal to the connected face 13 of the bearing part 12 and frame part 11. Since this displacement direction is an orthogonal direction to the direction of a cutter coming in contact with a workpiece, the thermal deformation of the bearing part 12 has no effect on workpiece machining accuracy.