JP2003127045A - Main spindle equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain excellent processing precision by preventing occurrence of thermal displacement due to a cooling route. SOLUTION: A bearing housing 2 is composed of an inner hosing 8 for holding a bearing row 4, an outer housing 9, and a sleeve 11. Between the inner housing 8 and the outer housing 9, and also between the sleeve 11 and the outer housing 9, a spiral outward-going route 12 and a returning route 13 are formed respectively, with both of their front ends connected with each other through a connection hole 14. Furthermore, at the rear side of the outer housing 9, a supply route 15, which is connected with the rear end of the outward-going route 12, and a recovery route 16, which is linked with the rear end of the return route 13, are formed individually.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the structure of a spindle device provided in a machine tool such as a machining center.

[0002]

2. Description of the Related Art FIG. 2 shows a conventional spindle device.
The spindle device 20 is configured such that a coaxial spindle 22 is rotatably supported by a bearing row 23 in a cylindrical bearing housing 21. Reference numeral 24 is a tool holder detachably provided on the front end of the spindle 22 (left side in FIG. 2), and 25 is provided so as to be movable back and forth around the axis of the spindle 22 to expand and contract a collet 26 that holds the tool holder 24. It is an advancing / retreating rod. Further, in the bearing housing 21, a spiral path 27 that spirals around the bearing row 23 is formed, and a drill hole 28 is connected to the front end of the spiral path 27 to connect the bearing housing 21. A cooling path that reciprocates back and forth is formed. Further, at the rear end of the spiral path 27, a supply path 30 formed by connecting a drill hole to an inlet 29 at the rear of the bearing housing 21 is formed, and in the drill hole 28, a supply path 30 is formed.
Recovery paths 32 formed by similarly connecting drill holes are connected to the outlet 31 at the rear of the bearing housing 21. Therefore, the coolant (coolant) supplied from the inlet 29 enters the spiral path 27 through the supply path 30,
The bearing row 23 is cooled while uniformly orbiting the circumference of the bearing row 23, and is collected from the outlet 31 through the recovery hole 32 from the drill hole 28.

[0003]

In the bearing housing 21, a drill hole 28, which serves as a return path for the cooling path, is formed so as to penetrate the bearing housing 21 substantially in the front-rear direction, so that the passage amount of the coolant is the spiral path 27. Together with this, the number of parts increases and the cooling action tends to be uneven. Therefore, when machining is performed by the spindle device 20, if there is a temperature change such as when the rotational speed of the spindle 22 increases, the vicinity of the drill hole 28 of the bearing housing 21 is cooled more than other portions, and thermal imbalance occurs. However, there is a problem that the spindle device 20 is tilted due to thermal displacement to reduce the machining accuracy.

Therefore, an object of the present invention is to provide a spindle device capable of preventing thermal displacement due to a cooling path and maintaining good machining accuracy.

[0005]

In order to achieve the above object, the invention as set forth in claim 1 forms a cooling path in a coaxial double cylinder shape that evenly covers a bearing, and supplies a coolant to one side. And a return path connected to the coolant recovery side, and a return path connected to the coolant recovery side. In addition to the object of claim 1, the invention according to claim 2 makes it possible to easily form the cooling path at a suitable position close to the bearing, and yet to prevent the rigidity from being lowered by the cooling path, the bearing housing Is formed by coaxially enclosing three divided housings having different diameters, and a forward path is formed on one side between the inner and outer circumferences of each divided housing and a return path is formed on the other side. The term "cylindrical" used in the present invention includes not only the cylinder itself, but also a form in which the cylinder is partially formed, such as a spiral shape, a mesh shape, or a lattice shape.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a partial vertical cross-sectional view of a spindle device 1. The spindle device 1 is coaxially supported by a cylindrical bearing housing 2 and a bearing row 4 formed of a plurality of ball bearings in the bearing housing 2. And a spindle 3. A tool holder 5 is detachably attached to the front end of the spindle 3 (on the left side in FIG. 1), and a collet 6 that grips the tool holder 5 is expanded and contracted on the shaft center of the spindle 3 by moving back and forth in the axial direction. A forward / backward rod 7 is provided. The rotation of the spindle 3 and the forward / backward movement of the forward / backward rod 7 are controlled by a servomotor and hydraulic pressure (not shown), respectively.

The bearing housing 2 includes an inner housing 8 for holding the bearing row 4, an outer housing 9 which is coaxially mounted on the inner housing 8 and is integrally fixed by a plurality of bolts 10, 10 ,. 3 with the sleeve 11 which is coaxially mounted on the housing 9 and fixed integrally
Formed from two split housings. Inner housing 8
A groove is formed in a spiral shape around the bearing row 4 on the outer periphery of the cylindrical housing 12 to form a cylindrical outward path 12 that evenly covers the bearing row 4 with the inner peripheral surface of the outer housing 9. There is. Similarly, a groove is spirally formed on the inner circumference of the sleeve 11,
A cylindrical return path 13 that is coaxial with the outward path 12 and evenly covers the bearing row 4 is formed between the outer housing 9 and the outer peripheral surface. A connection hole 14 that connects the front ends of the forward path 12 and the return path 13 is radially provided in front of the outer housing 9 to form a cooling path that can reciprocate back and forth around the bearing row 4. Has been formed.

On the other hand, in the rear part of the outer housing 9,
The supply path 15 connected to the rear end of the outward path 12 is formed by the connection of the linear drill holes, and the return path is formed at the position symmetrical with the supply path 15 by the connection of the linear drill holes. Collection path 16 connected to the rear end of 13
Are formed. Reference numeral 17 is a coolant supply pipe connected to the inlet of the supply passage 15, and 18 is a coolant recovery pipe connected to the outlet of the recovery passage 16. Therefore, when the coolant is supplied from the supply pipe 17, the coolant becomes
From the supply path 15 to the outward path 12, the bearing row 4 is cooled while uniformly circulating around the bearing row 4 along the outward path 12. When the coolant that has finished cooling the bearing row 4 reaches the front end of the outward path 12, the coolant enters the return path 13 through the connection hole 14 and travels along the return path 13 evenly around the outward path 12 to the rear side. It will reach the end and will be recovered from the recovery pipe 18 through the recovery path 16.

As described above, according to the spindle device 1 of the above-described embodiment, the cooling path is the coaxial double cylindrical forward path 12 and the return path 13 that evenly cover the bearing row 4, and the forward path 12 supplies the coolant. Side and the return path 13 are connected to the coolant recovery side, respectively, a cooling path that reciprocates around the bearing row 4 can be uniformly formed in the bearing housing 2, and a thermal imbalance in the radial direction of the bearing housing 2 can be achieved. There is no place to cool down. Therefore, even if the heat generation amount of the bearing housing 2 is changed by changing the rotation speed of the spindle 3,
The thermal displacement does not occur, the inclination of the spindle device 1 is prevented, and high machining accuracy can be maintained.

In general, for cooling the bearing, it is more effective to allow the coolant to flow as close to the bearing as possible rather than forming a large space in the cooling path. Therefore, it is necessary to reduce the diameter of the bearing housing. However, when the diameter of the bearing housing is reduced, the rigidity of the spindle device is reduced and cutting is affected. However, here, the bearing housing 2 is composed of an inner housing 8 having a different diameter, an outer housing 9 and a sleeve 11.
The two divided housings are coaxially externally formed in order, and the forward path 12 is formed on one side between the inner and outer circumferences of the respective divided housings, and the return path 13 is formed on the other side. Without reducing the rigidity of the device 1,
It can be easily installed near the bearing row 4 having a high cooling effect.

Although the forward path and the return path are spiral in the above embodiment, one or both of them may be a cylindrical space, a mesh shape or a lattice shape as long as they do not generate thermal imbalance. It is possible to change the design such as the space of Further, in the above-mentioned form, the route going inside,
Although the outer side is used as the return path, the same effect can be obtained by reversing the forward and backward directions. Besides, it is also possible to directly connect the coolant supply pipe and the recovery pipe to the forward route and the return route by eliminating the supply route and the recovery route.

[0012]

According to the first aspect of the present invention, the cooling path is formed in the shape of a coaxial double cylinder that evenly covers the bearing, and one of the forward paths is connected to the coolant supply side, and the other is the forward path. By using as a return path that is connected to the coolant recovery side, a cooling path that reciprocates around the bearing can be evenly formed inside the bearing housing, and there are places where cooling is performed in a thermal unbalance in the radial direction of the bearing housing. Absent. Therefore, even if the amount of heat generated by the bearing housing changes due to changes in the rotation speed of the spindle, thermal displacement does not occur, tilting of the spindle device is prevented, and high machining accuracy can be maintained. According to the invention described in claim 2, in addition to the effect of claim 1, the bearing housing is formed of the three divided housings, and the forward path is provided to one of the inner and outer circumferences of each divided housing,
By forming each of the return paths on the other side, the forward path or the return path for cooling can be easily provided near the bearing having a high cooling effect without lowering the rigidity of the spindle device.

[Brief description of drawings]

FIG. 1 is a partial vertical cross-sectional view of a spindle device.

FIG. 2 is a partial vertical sectional view of a conventional spindle device.

[Explanation of symbols]

1 ... Spindle device, 2 ... Bearing housing, 3 ... Spindle, 4 ... Bearing row, 8 ... Inner housing, 9 ... Outer housing, 11 ... Sleeve, 12 ... Forward path,
13 ... Return path, 14 ... Connection hole, 15 ... Supply path, 16 ... Recovery path

Claims (2)

[Claims] 1. A spindle having a tool mountable at a front end thereof, and a bearing housing having a bearing on an inner periphery thereof for axially supporting the spindle, wherein a coolant is provided in the bearing housing around the bearing. A spindle device having a reciprocating cooling path formed therein, wherein the cooling path is formed in a coaxial double cylinder shape that evenly covers the bearing, and one of them is a forward path connected to the coolant supply side. The spindle device, wherein the other is a return path connected to the coolant recovery side. 2. The bearing housing is formed by coaxially covering three divided housings having different diameters in order, and a forward path is formed in one of the inner and outer circumferences of each divided housing, and a return path is formed in the other. The spindle device according to Item 1.