JPH0751975A - Longitudinal movement device for worktable - Google Patents

Abstract

PURPOSE:To reduce the occurrence of relative displacement in a longitudinal direction owing to thermal displacement of a position where a work on a work table longitudinally and laterally moving is machined and the position of the spindle tool of a spindle head at the front of a column. CONSTITUTION:The rear end of a feed twist shaft 15 in a longitudinal direction is supported to a support bearing 12 in a position in the phoximity of a column 3, and the front end thereof is coupled to a longitudinal feed motor 17 through a flexible coupling 16. The screw shaft 15 is joined in a screwed-in state with the feed nut 29 of a slide body 26 and a worktable 31 is guided over a slide body 26 laterally movably through a rail 32.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a work table longitudinal movement device for a machine tool having a fixed column erected on a bed and having a spindle head movable up and down.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 4, in a vertical machining center, a column 3 is erected on a bed 2, and a spindle head 5 can be raised and lowered by a screw feed mechanism 7 on the front surface of the column 3. I have been informed. A work table 31 below the spindle 8 of the spindle head 5 is guided on a slide body 26 that moves back and forth so as to be able to move left and right by a feed screw shaft 35 that rotates by a left and right feed motor, and a screw feed mechanism 14 that moves the slide body 26 back and forth. The feed screw shaft 15 of the
It is supported by a support bearing 12 provided at a position that is considerably distant from the column 3 to the front (to the left in FIG. 4), and the rear end thereof is connected to the longitudinal feed motor 17.

[0003]

When machining is started in such a vertical machining center, the lifting motor 40, the spindle motor 41, the longitudinal feed motor 17, and the lateral feed motor are rotationally controlled, and the corresponding feeding is performed. The screw shaft and the main shaft 8 are rotated. Such a motor and a feed screw shaft generate heat by rotation, and the heat causes the main shaft head 5 supported in such a manner as to project forward from the column 3, that is, the main shaft (tool 9) position from the true position. Only a shift to the front. On the other hand, the feed screw shaft 15 extends rearward with respect to the support bearing 12 due to this heat, so that the work table 31 is displaced rearward from the true position by b. As a result, the machining position of the workpiece on the work table 31 in the front-rear direction by the spindle tool deviates from the true position by the sum (a + b) of the deviations of the both, and there is a problem that the machining position accuracy in the front-rear direction decreases. . In order to suppress the heat generation due to the rotation of the feed screw shaft, cool it to suppress the elongation, or detect the elongation of the screw shaft and correct the screw shaft rotation amount. However, there is a drawback that the device is complicated and expensive. An object of the present invention is to improve the machining position accuracy in the front-rear direction by a spindle tool for a work on a work table.

[0004]

In order to solve the above problems, according to the present invention, a spindle head is vertically guided on a front surface of a column erected on a bed, and the spindle head is rotatably supported by a bed. A slide body is provided on the top of the slide body so that it can be moved back and forth by a screw feed mechanism having a feed screw shaft in the front-back direction that is rotated by a front-back feed motor, and a work table is provided on the slide body so that the work table can be moved sideways. In the machine, the rear end of the feed screw shaft in the front-rear direction is supported by a support bearing provided close to the column, and the front end of the feed screw shaft is free from thermal displacement of itself. And

[0005]

The heat generated by the rotation of the motor or the feed screw shaft causes the feed screw shaft for the back and forth movement of the table to extend forward with reference to the support bearing close to the column. On the other hand, the spindle head on the front side of the column also extends forward due to the heat generated by the rotation of the spindle bearing. In this way, the front-back direction position of the main-axis tool of the main-axis head shifts forward, and the front-back direction position of the work table also shifts forward, so the relative shift between the two in the front-back direction becomes small, and the machining position accuracy improves.

[0006]

EXAMPLE In FIG. 1, on a bed 2 of a machine tool 1,
Column 3 is erected. A column head 3 is vertically guided by a vertical guide rail 4 in the column 3, and the spindle head 5 is rotated by a feed motor (not shown) arranged above the column 3 in the Z-axis. A screw feed mechanism 7 having a feed screw shaft 6 controls elevation. Reference numeral 8 is a spindle, and 9 is a tool.

Below the main spindle head 5, a work table 31 is movable back and forth and left and right.
The base 11 of is fixed to the bed 2. A bearing case 13 containing a support bearing 12 is fixed to the base 11 at a position close to the column 3, and the rear end of the feed screw shaft 15 in the front-rear direction of the screw feed mechanism 14 is rotatable on the bearing case 13. Is supported by. Feed screw shaft 1
The tip of 5 is connected via a flexible joint 16 to an output shaft 18 of a longitudinal feed motor 17 attached to the front end of the base 11. The flexible joint 16 has a well-known structure shown in FIG. 3, and includes a first flange 20 and a second flange 21 via a flexible plate 22 made of a leaf spring material to form the reamer bolt 2.
When the feed screw shaft 15 extends forward in the axial direction due to thermal displacement of itself, the flexible plate 22 bends and absorbs this.

As shown in FIG. 2, guide rails 25 in the front-rear (Y) direction are attached to the left and right sides of the feed screw shaft 15, and a slide body 26 is guided on the guide rails 25 so as to be movable back and forth. The slide body 26 connects the four guides 27, which are guided by the guide rails 25, with the connecting member 28.
Connecting member 2 on the side of the support bearing 12
A feed nut 29 that is screwed onto the feed screw shaft 15 is integrally mounted on the unit 8. A rail 32 attached to the lower surface of the work table 31 and extending in the left-right (X) direction is guided to be movable left and right in a guide portion 30 provided on the upper surface of each guide 27. A feed screw shaft 35 rotated by a left and right feed motor 34 attached to a connecting member 28 of the slide body 26 is screwed into a feed nut 33 on the lower surface of the work table 32.

The work is clamped on the work table 31, and the front-back feed motor 17, the left-right feed motor 34, the Z-axis motor and the main-axis motor are rotationally controlled to process the work. At this time, with respect to the front-back direction, the feed screw shaft 1
5 is due to rotation of itself and heat generation of the forward / backward feed motor 17,
A forward expansion is generated with reference to the support bearing 12 close to the column 3. On the other hand, the spindle head 5 protrudingly supported on the front surface of the column 3 is also thermally displaced forward by heat generated by the spindle motor, the spindle 8 or the feed screw shaft 6. As a result, the spindle tool 9 shifts forward from the true position, but the work table 31
Also shifts forward from the true position, so spindle tool 9
Then, the relative displacement between the workpiece on the work table 31 and the position to be machined in the front-rear direction becomes extremely small, and the machining position accuracy is improved.

[0010]

As described above, according to the present invention, the rear end of the front-rear feed screw shaft of the slide body is supported at a position close to the column. The displacement direction of the table in the front-rear direction can be made the same direction, whereby the relative displacement of the workpiece and the spindle tool in the front-rear direction can be reduced, and the machining position accuracy can be improved.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a table unit.

FIG. 2 is a sectional view taken along the line II-II in FIG.

FIG. 3 is a sectional view of a flexible joint.

FIG. 4 is a conventional technique.

[Explanation of symbols]

2 beds, 3 columns, 5 spindle heads, 8
Spindle, 9 tools, 12 support bearings, 14 screw feed mechanism, 15 feed screw shaft, 16 flexible joint,
26 slides, 31 work table

Claims (2)

[Claims] 1. A spindle head is vertically guided on a front surface of a column erected on a bed, the spindle is rotatably supported by the spindle head, and a slide body is mounted on a bed and a front-rear feed mode is provided.
In a machine tool that is movable back and forth by a screw feed mechanism that has a feed screw shaft in the front-rear direction that is rotated by A forward / backward movement device for a work table, characterized in that the end is supported by a support bearing provided near the column, and the front end of the feed screw shaft is free from thermal displacement of itself. 2. The work table longitudinal movement device according to claim 1, wherein the front end of the feed screw shaft is connected to the output shaft of the longitudinal feed motor through a flexible joint.