JPH0620715B2 - Mechanism for equalizing thermal displacement of facing headstock - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mechanism for equalizing the amount of thermal displacement in opposing parts of each headstock of a machine tool having an opposed headstock.

2. Description of the Related Art In a machine tool that chucks both ends of a work piece with opposed headstocks and performs turning with a tool rest provided on the headstock, it is not always said that both headstocks are operating under the same conditions. However, due to heat generated by the spindle bearing, the built-in motor, the chuck cylinder, etc., the temperatures of the opposite parts of the two headstocks are not the same. Therefore, as shown in the lathe with an opposed headstock in FIG. 1, when the dimensions a and b above the spindle center line of the headstock main body have a difference in thermal displacement due to a temperature difference,
It appears as an outer diameter dimensional error as a machining accuracy, and if the misalignment in the vertical (X-axis) direction of both spindle centerlines occurs due to the temperature difference between the dimensions a'and b'below the spindle centerline, the machining accuracy becomes It appears as a cylindricity of the outer diameter. Further, if the center lines of the both spindles are misaligned in the horizontal (Y-axis) direction due to the temperature difference, the misalignment at the time of milling appears as a machining accuracy.

Conventionally, in order to eliminate the adverse effect on machining accuracy due to these temperature differences, an oil jacket was provided on both headstocks and the temperature of both headstocks was adjusted by circulating oil whose temperature was controlled by an oil con, etc. .

Problems to be Solved by the Invention The temperature adjustment by the oil-con described in the prior art has a problem that the structure of the headstock becomes complicated and an expensive and large-scale oil-con unit is required.

The present invention has been made in view of the above problems of the conventional technique, and an object of the present invention is to improve machining accuracy by making the temperatures of opposite parts of both headstocks the same. It is intended to provide an inexpensive and simple structure.

Means for Solving the Problems In order to achieve the above object, the thermal displacement equalizing mechanism of the facing headstock of the present invention has a plurality of corresponding ends of each headstock, each end of one heat pipe. Part,
The heat pipe provided in the movable portion has a flexible portion formed in the middle thereof, and the corresponding portions of the respective headstocks are thermally coupled independently to reduce the temperature difference between the corresponding portions.

The different temperatures of the opposite parts of both headstocks due to the temperature rise generated by the action operation are brought close to the same temperature by the heat transfer operation by the heat pipes, and the difference in the thermal displacement amount of the opposite parts is reduced.

Example An example will be described with reference to FIGS. 1 to 3. On both sides of the bed 1, a main body 2 of an A headstock and a main body 3 of a B head, which are symmetrical with respect to the center, are fixed to face each other, and the main bodies 2 and 3 are square holes 2b and 3b in the Z-axis direction. Are formed on the four sides of the square hole, and guide grooves in the Z-axis direction are formed in which four slide guide surfaces 2a and 3a are formed. And the square holes 2b, 3b
Main spindle rams 4 and 5 having a rectangular cross section and having guide fins in the Z-axis direction that are slidably fitted in the guide grooves through the jib.
However, the spindle rams 4 and 5 are concentrically fitted and inserted, and the NC drive servomotors 6 and 7 fixed to the main bodies 2 and 3 can synchronously or independently move and position them. Main shafts 8 and 9 are rotatably supported on the main shaft rams 4 and 5 by a plurality of bearings, and chucks 10 and 11 are attached to the ends of the main shafts with their gripping claws facing each other. The main shafts 8 and 9 have a built-in main shaft ram. Is rotated by built-in motors 12 and 13, and both ends of the shaft workpiece W are gripped by the chucks 10 and 11.

The tool rest units 14 and 15 are mounted on the main bodies 2 and 3 of the headstock so as to face each other symmetrically with respect to the center, and are vertically cut (X axis) in the frames 16 and 17 of the tool rest unit. Center mounts 18 and 19 are movably provided on the slide guide surface in the direction, and are moved and positioned by NC drive servomotors 20 and 21 fixed to the frames 16 and 17. The tool rests 22 and 23 are fixed on the middle stand, and the tool rests 22 and 23 are provided with turrets 24 and 25 that can be swivel-indexed on a vertical plane in the X-axis direction.
Bits 26 and 27 are detachably attached to 25 tool attachment stations, respectively.

Further, both ends of the heat pipe 30 are attached to the lower part of the main body 2 of the A headstock and the lower part of the main body 3 of the B headstock.
In addition, a heat pipe 31 is provided on the upper part of the main body 2 and the upper part of the main body 3.
Both ends of are attached. Further, both ends of the heat pipe 32 are also attached to the main spindle rams 4 and 5, and the heat pipe 32 is a flexible one so that the main spindle rams 4 and 5 can move in the Z-axis direction. 32
For movement, the main bodies 2 and 3 are provided with thin windows 2c and 3c in the Z-axis direction. Both ends of the heat pipes 30, 31, 32, which are heat exchange portions, are the headstock main bodies 2, 3 and the main spindle ram 4.
Each of the parts 5 and 5 is attached so as to have a large heat conduction area, and the intermediate pipe connecting the attachments is covered with a heat insulating material. The heat pipe installed in this way is filled with the working fluid in the pipe, and this working fluid is heated on either the main body of the headstock or the high temperature side of the spindle ram to obtain the heat of vaporization and evaporate the pressure. Due to the difference, it moves to the low temperature side, where it radiates heat and is liquefied, and the wick causes capillary action to return the heat to the high temperature side. A well-known one having a function of making the temperature uniform is used, and it is provided horizontally because the moving direction of heat cannot be specified in either direction.

Next, the operation of this embodiment will be described. The shaft workpiece W whose both ends are gripped by the spindle chucks 10 and 11 is
Turning is performed by the built-in motors 12 and 13, and turning is performed by movement of the tool rest in the X-axis direction and synchronous movement of the spindle rams 4 and 5 in the Z-axis direction. The main spindle rams 4 and 5 have built-in heat sources such as a main spindle bearing, a built-in motor, and a chuck cylinder, and the temperature rises with the lapse of operating time. The temperature of the spindle ram is transmitted to the main body 2, 3 of the headstock and the main body 2, 3
Temperature rises. At this time, the temperatures at the positions where the main bodies 2 and 3 of the headstock and the main spindle rams 4 and 5 face each other do not always become the same even if both main spindles rotate in the same way by both drives, and a temperature difference can occur. Further, when both spindles are driven for a certain time by one side drive and then switched to both drives and rotated at the same rotation, the headstock bodies 2, 3 and the spindle rams 4, 5 are obviously larger than the above case. The temperature at each opposite position is different. Therefore, the lower temperature difference between the A headstock body 2 and the B headstock body 3 is due to the heat pipe 30, and the upper temperature difference is due to the heat pipe 31.
And the temperature difference between the main spindle rams 4 and 5 is made uniform by the heat pipe 32, and the difference in the amount of thermal displacement between the parts is reduced.

EFFECTS OF THE INVENTION Since the present invention is configured as described above, it has the following effects.

Since both ends of a single heat pipe were attached to multiple opposing parts of the opposing headstock, the two headstocks could be irrespective of whether they were operated under the same or different conditions. The difference in temperature between the corresponding portions is reduced, and accordingly, the difference in the amount of thermal displacement is reduced, and the working accuracy can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view of a lathe with an opposed headstock, and FIG. 2 is A of FIG.
FIG. 3 is a sectional view taken along line A-A, and FIG. 3 is a sectional view taken along line BB in FIG. 2 ... A headstock body, 3 ... B headstock body 4,5 ... spindle ram 30,31,32 ... heat pipe

Claims (1)

[Claims] 1. A machine tool having opposed headstocks, wherein each headstock (2 to 5) is provided with both ends of one heat pipe (30 to 32) at corresponding parts, and is movable. The heat pipe provided in each part is formed with a flexible part in the middle thereof, and the corresponding parts of the respective headstocks are thermally connected independently to reduce the temperature difference between the corresponding parts. Mechanism for equalizing thermal displacement of the facing headstock.