JPH04331004A - Spindle device - Google Patents

Abstract

PURPOSE:To enable a desired cutting even if a spindle and static pressure bearings or a thrust runner are expanded due to heat by aligning a fixing surface of a work mounting side static pressure bearing on the spindle stock with a thrust static pressure bearing surface on the thrust runner in the axial direction. CONSTITUTION:The positions of a fixing surface 14 of a bearing 13 on a spindle stock 10 and a thrust static pressure bearing surface 13b of the bearing 13 on a thrust runner 16 are aligned with each other in the axial direction of a spindle. A chuck 21 in which a work W is installed is fixed to the spindle 11 through a low thermal expansion member 19. The spindle 11 and static pressure bearings 12 and 13 are expanded due to heat generated on radial static pressure bearing surfaces 12a and 13a by the rotation of the spindle 11. This displacement does not affect the work W since the upper part over the unfixed thrust static pressure bearing 13b is affected by the displacement with the fixing surface 14 as a reference.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spindle device in which elongation due to thermal expansion does not affect machining.

0002

2. Description of the Related Art A conventional spindle device of this type will be explained with reference to FIG. In Fig. 2, 10 is the headstock and this headstock 1
0, a main shaft 11 is rotatably supported around a vertical axis via hydrostatic bearings 12 and 13. And headstock 1
0 is closed by a cap 10a. Further, a rotor 30 is fixed to the upper end of the main shaft 11, and a stator 32 is fixed to the casing 31 at a position corresponding to the rotor 30. The casing 31 is fixed to the upper end of the headstock 10, and the rotor 30, stator 32, and casing 31 constitute a motor that rotationally drives the main shaft 11. Further, a drive inverter 33 is connected to the stator 32 and supplies a control current for controlling the rotation of the rotor 30 .

At the lower end of the headstock 10, a hydrostatic bearing 1
3 is fixed to a fixing surface 14 formed on the front surface of the headstock 10 by bolts 15. At the lower end of the main shaft 11, a contact surface 18 opposing the thrust bearing surface 13b of the hydrostatic bearing 13 is provided.
A cylindrical thrust runner 16 having a diameter and protruding in the radial direction.
A vacuum chuck 21 that grips a disk-shaped workpiece W by suction is fixed to the main shaft 11 with a bolt 22 via a thrust runner 16. Further, the auxiliary member 23 that holds the outer periphery of the thrust runner 16 and the vacuum chuck 21 is attached to the hydrostatic bearing 1 by means of a bolt 24.
It is fixed to 3.

0004

[Problem to be Solved by the Invention] In such a conventional technique, heat generated on the radial hydrostatic bearing surfaces 12a, 13a of the main spindle 11 and the hydrostatic bearings 12, 13 during machining causes damage to the main spindle 11 and the hydrostatic bearings 12, 13. , 13 expand. At this time, the thrust static pressure bearing surface 1 of the static pressure bearing 13 on the work mounting side
3b is a fixing surface 14 of this hydrostatic bearing 13 to the headstock 10.
Since it is located closer to the mounting side of the workpiece W, displacement of the main shaft 11 and the hydrostatic bearing 13 in the axial direction affects the workpiece W via the thrust runner 16 and the vacuum chuck 21. Also,
When the thrust runner expands due to the heat generated on the thrust static pressure bearing surface 13b, it affects the position of the workpiece W via the vacuum chuck 21. For this reason, there was a problem in that the position of the workpiece W was shifted in the axial direction, making it impossible to perform desired machining.

[0005]

[Means for Solving the Problems] The present invention has been made to solve the above-mentioned problems, and includes a chuck side that is fixed to a chuck side fixing surface of a headstock, and that is aligned with this fixing surface in the axial direction of the main spindle. a thrust runner having a contact surface opposing the hydrostatic bearing surface of the hydrostatic bearing and fixed to the main shaft; and a thrust runner fixed to the main shaft. and a low thermal expansion member provided at the axis of the chuck to fixedly support the chuck.

[0006]

[Function] By aligning the fixing surface 14 of the bearing 13 on the work W mounting side to the headstock 10 and the thrust bearing surface 13b of this bearing 13 with the thrust runner 16 in the axial direction of the main spindle, the fixing surface 14 Since the bearing 13 is displaced only in the opposite direction to the chuck 21 due to the thermal expansion of the bearing 13, the displacement in the axial direction due to the thermal expansion of the bearing 13 does not affect the workpiece W. Furthermore, since the chuck 21 on which the workpiece W is attached is fixed via the low thermal expansion member 19 between it and the main shaft, the thrust runner 16 does not come into contact with the chuck 21 even if the thrust runner 16 expands thermally, and the axis of the workpiece W Does not affect the position of the direction.

[0007]

[Embodiment] An embodiment of the present invention will be explained based on the drawings. In FIG. 1, reference numeral 10 denotes a headstock, and a main shaft 11 is rotatably supported on the headstock 10 via hydrostatic bearings 12 and 13 around a vertical axis. The upper end of the headstock 10 is closed by a cap 10a. Also, spindle 1
A rotor 30 is fixed to the upper end of the housing 1, and a stator 32 is fixed to a casing 31 at a position corresponding to the rotor 30. The casing 31 is fixed to the upper end of the headstock 10, and the rotor 30, stator 32, and casing 31 constitute a motor that rotationally drives the main shaft 11. Further, a drive inverter 33 is connected to the stator 32 and supplies a control current for controlling the rotation of the rotor 30 .

At the lower end of the headstock 10, a hydrostatic bearing 1
3 is fixed to a fixed surface 14 of the headstock 10 by bolts 15, and this hydrostatic bearing 13 is formed with a thrust hydrostatic pressure bearing surface 13b whose axial position coincides with the fixed surface 14. A cylindrical thrust runner 16 projects in the radial direction, and is fixed to the lower end of the main shaft 11, with an abutment surface 18 opposing the thrust static pressure bearing surface 13b. A cylindrical low thermal expansion member 19 having a small coefficient of expansion and which is longer than the thrust runner 16 in the axial direction is inserted into the axis of the thrust runner 16 so as to be in contact with the main shaft 11 . A vacuum chuck 21 that grips a disc-shaped workpiece W by suction is fixed to the main shaft 11 with a bolt 22 via a low thermal expansion member 19 with a gap between it and the thrust runner 16. Further, an auxiliary member 23 that holds the outer circumferences of the thrust runner 16 and the vacuum chuck 21 is fixed to the hydrostatic bearing 13 by bolts 24.

On the other hand, a slight gap is formed in the upper part of the main shaft 11 with the cap 10a in the axial direction, and a suction passage 34 for causing the vacuum chuck 21 to suction and hold the work W is formed inside the main shaft. Next, the operation of the spindle device of this embodiment will be explained based on the above-described configuration. vacuum chuck 2
A workpiece W is mounted on the main shaft 1, the drive inverter 33 is activated, the main shaft 11 is rotated by the motor, and a table (not shown) equipped with a cutting tool is fed and moved in a direction orthogonal to the axial direction of the main shaft 11, thereby cutting the workpiece W. I do.

In this cutting process, the main shaft 11 and the hydrostatic bearings 12, 13 thermally expand due to the heat generated on the radial static pressure bearing surfaces 12a, 13a due to the rotation of the main shaft 11. However, by aligning the fixed surface 14 of the hydrostatic bearing 13 to the headstock 10 and the thrust hydrostatic bearing surface 13b of the thrust runner 16 of this hydrostatic bearing 13 in the axial direction, the hydrostatic bearing 13 is heated. Even if it expands, this displacement will cause the fixed surface 14
Thrust hydrostatic bearing surface 13 that is not fixed with reference to
Since the displacement acts on the rotor 30 side above b, the workpiece W is not affected. Further, the vacuum chuck 21 is connected to the thrust runner 1 through the low thermal expansion member 19 by the bolt 22.
Since the thrust runner 16 is attached to the main shaft 11 with a gap between it and the vacuum chuck 21, even if the thrust runner 16 expands thermally,
does not affect the axial position of the Therefore, since the workpiece W is not displaced in the axial direction, desired cutting can be performed. In addition, in the above embodiment, the thrust runner 16 and the low thermal expansion member 19 are separated from each other, and the hydrostatic bearing surface 13
Although a metal that is easy to process is used in b, the metal is not limited to this, and if the process on the hydrostatic bearing surface 13b is ignored, the thrust runner 16 and the low thermal expansion member 19 can be integrated to achieve low thermal expansion. It may be formed from a member. In this case, there is no need to form a gap between the thrust runner 16 and the vacuum chuck 21.

[0011]

According to the spindle device of the present invention, the fixing surface of the hydrostatic bearing on the work mounting side to the headstock and the thrust hydrostatic pressure bearing surface of the thrust runner of this hydrostatic bearing are connected in the axial direction of the spindle. , and by fixing the chuck that attaches the workpiece to the main shaft with a gap between it and the thrust runner through a low thermal expansion member, the axial displacement due to thermal expansion of the main shaft and hydrostatic bearing does not affect the workpiece. do not. Therefore, even if the main shaft, the hydrostatic bearing, or the thrust runner undergo thermal expansion, the desired cutting process can be performed.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a spindle device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a prior art.

[Explanation of symbols]

10 Headstock 11 Main shaft 12, 13 Static pressure bearing 13b Thrust static pressure bearing surface 14 Fixed surface 16 Thrust runner 18 Contact surface 19 Low thermal expansion member 21 Chuck

Claims (1)

[Claims] Claim 1: Consisting of a headstock, a main shaft that is rotatably supported by static pressure on the headstock, a motor that rotationally drives the main shaft, and a chuck that holds a workpiece inserted at the tip of the main spindle. In a spindle device, a bearing is fixed to a chuck-side fixed surface of the headstock and has a chuck-side thrust hydrostatic pressure bearing surface that coincides with the fixed surface in the axial direction of the main spindle, and a bearing that opposes the hydrostatic pressure bearing surface of this bearing. A main shaft comprising: a thrust runner having an abutment surface and fixed to the main shaft; and a low thermal expansion member provided at the axis of the thrust runner fixed to the main shaft and fixedly supporting the chuck. Device.