JPH10113845A - Spindle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively transfer heat maintaining sufficient rigidity and stably rotate a spindle at a high speed. SOLUTION: This spindle is provided with an internal pipe 2 wherein a plurality of grooves 2a, which holds the base end of a tool at its tip and faces in the longitudinal direction along the axial direction are spacedly formed with a specified interval, an external pipe 3, in which a bearing 23a is fitted to the external peripheral face of the internal pipe 2 so as to cover the groove 2a and the outer section of the internal pipe 2 and to a position close to the tip of the external peripheral face and also has a cooling fin 3a, in which cooling liquid contacts a section close to the base end of the external peripheral face, holding pipe 4, which is driven to rotate coaxially with the base end of the external pipe 3, and the heat transferring medium such as methanol contained in the groove 2a. A communication passage 2b, through which the groove 2a of the internal pipe 2 is communicated, is formed in the internal pipe 2, and the internal peripheral face of the external pipe 3 is also tapered so that the internal face of the cooling fin 3a of the external pipe 3 is tapered toward the base end side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a spindle applied to a machine tool such as a machining center.

[0002]

2. Description of the Related Art The structure of a spindle of a machine tool such as a machining center is shown in FIG. In FIG.
21 is a housing, 21a to 21c are lubricating oil supply ports, 2
1d and 21e are lubricating oil discharge ports, 21f is a coolant supply port,
21g is a coolant discharge port, 21h is an air supply port, 22 is a spindle, 22a is a cooling fin, 23a to 23c are bearings, 24 is a stator, and 25 is a rotor.

[0003] A housing 21 rotatably supports a spindle 22 via bearings 23a to 23c. The stator 24 is attached to the inner peripheral surface of the housing 21,
The rotor 25 is provided on the outer peripheral surface of the spindle 22, and the stator 24 and the rotor 25 are disposed so as to face each other.

[0004] Lubricating oil supply ports 21a to 21c are provided in the housing 21 so that lubricating oil can be supplied to the bearings 23a to 23c. Lubricating oil outlets 21d, 21e
Is provided in the housing 21 so that the lubricating oil used in the bearings 23a to 23c can be discharged to the outside.
The coolant supply port 21f is formed in the housing 21 so that coolant can be supplied to a cooling fin 22a formed on the outer peripheral surface of the spindle 22. Coolant outlet 21g
Is formed in the housing 21 so that the cooling liquid used for cooling the cooling fins 22a can be discharged to the outside. The air supply holes 21h are formed in pairs in the housing 21 so as to sandwich the coolant supply port 21f and the coolant discharge port 21g in the axial direction of the spindle 22, and send air toward the outer peripheral surface of the spindle 22. By supplying the coolant, it is possible to prevent the coolant from leaking in the axial direction.

That is, the spindle 22 is connected to the stator 24
When the current flows through the bearings 23a to 23c, the cooling fin 22a is rotated with respect to the housing 21 by the cooling liquid from the cooling liquid supply port 21f. The heat generated from the heat-generating portion such as 23c is released to the outside to suppress the preload of the bearings 23a to 23c from becoming excessive.

However, when cooling is performed in this way, the distance between the bearing 23a and the cooling fins 22a results in not only poor cooling efficiency but also a large axial displacement of the spindle 22 along the axial direction. In some cases, a thermal gradient is easily formed, which may cause a decrease in accuracy of the spindle 22 or the like.

Therefore, as shown in FIGS. 4 and 5, a cylindrical heat pipe 51 is fitted coaxially with the inner peripheral surface of the spindle 32, or as shown in FIGS.
By providing a plurality of heat pipes 52 at predetermined intervals along the circumferential direction between the inner peripheral surface and the outer peripheral surface of the spindle 42, the cooling fins 32a, 42a and the bearing 2 are provided.
3a, the heat transfer efficiency with the spindle 32,
It has been considered to reduce the thermal gradient in the axial direction of 42.

[0008]

However, FIG.
As shown in FIG.
In this case, since the inner and outer diameters of the spindle 32 are specified, the thickness of the heat pipe 51 of the spindle 32 must be reduced, and the spindle 32 may have sufficient rigidity. I can no longer do it.

On the other hand, if the heat pipe 52 is provided on the spindle 42 as shown in FIGS. 6 and 7, the size of the heat pipe 52 in the radial direction cannot be increased. Since the heat transfer medium cannot be used, it is not only difficult to efficiently transfer heat, but also if the amount of the heat transfer medium in all the heat pipes 52 is not equal, the spindle 42 vibrates during rotation, Stable high-speed rotation becomes difficult.

In view of the above, an object of the present invention is to provide a spindle capable of efficiently transmitting heat while having sufficient rigidity and capable of performing stable high-speed rotation.

[0011]

A spindle according to the present invention for solving the above-mentioned problems is a spindle which is driven to rotate while holding a base end of a tool at a tip thereof, and is provided with a base end of the tool at a tip end. And an inner pipe in which a plurality of grooves directed in the longitudinal direction along the axial direction are formed on the outer peripheral surface at a predetermined interval along the circumferential direction, and shield the groove and the outside of the inner pipe. The outer tube is fitted to the outer peripheral surface of the inner tube, a bearing is fitted near the distal end of the outer peripheral surface, and the outer tube is brought into contact with the coolant near the base end of the outer peripheral surface. And a heat medium.

In the above-mentioned spindle, a communication passage for communicating the groove of the inner tube is formed in the inner tube.

In the above-mentioned spindle, the inner peripheral surface of the outer tube is tapered so that the inner diameter of a portion of the outer tube that comes into contact with the coolant becomes smaller toward the base end. And

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a spindle according to the present invention will be described with reference to FIGS. 1 is a sectional view showing the structure, and FIG. 2 is a sectional view taken along line II-II in FIG. However, for the housing and stator, etc.
In addition to omitting the description, the same members as those described in the above-described related art will be denoted by the same reference numerals as those used in the above-described related art, and the description thereof will be omitted.

In FIG. 1, reference numeral 1 denotes a spindle, and the spindle 1 has an inner tube 2 for holding a base end of a tool at a distal end.
And a cooling fin 3a which is tightly fitted to the outer peripheral surface of the inner pipe 2 by shrink fitting or the like and comes into contact with the coolant near the base end of the outer peripheral surface
And a holding tube which is fitted coaxially and tightly to the base end of the inner tube 2 and holds and rotates the inner tube 2. 4 is provided.

As shown in FIGS. 1 and 2, the inner tube 2 is formed with a plurality of grooves 2a extending longitudinally along the axial direction at predetermined intervals along the circumferential direction on the outer peripheral surface. A plurality of communication paths 2b communicating between the adjacent grooves 2a are formed at predetermined intervals along the axial direction. On the other hand, the outer tube 3
As shown in FIG. 1, the inner peripheral surface of the cooling fin 3a is formed in a tapered shape so that the inner diameter of the portion contacting with the cooling liquid becomes smaller toward the base end side of the inner tube 2. At the same time, an introduction pipe 3b communicating with the groove 2a and the communication passage 2b of the inner pipe 2 is provided in pairs so as to be point-symmetric about the axis of the inner pipe 2. The distal end and the proximal end between the inner tube 2 and the outer tube 3 are brazed with silver, and the space therebetween is completely sealed.
That is, the outer tube 3 is fitted to the inner tube 2 so as to shield the groove 2a of the inner tube 2 from the outside.

In the groove 2 a of the inner tube 2, a heat transfer medium such as methanol is filled with the introduction tube 3 b of the outer tube 3.
After the introduction of the heat transfer medium in the liquid phase, the introduction pipe 3b is completely closed by caulking and brazing silver.

That is, a heat pipe is constituted by the inner tube 2 and the outer tube 3 constituting the spindle 1. For this reason, it is possible to use a sufficient amount of the heat transfer medium while sufficiently securing the thickness of the spindle 1.

Therefore, heat from the bearing 23a and the like accompanying rotation is efficiently transmitted to the cooling fins 3a of the outer tube 3 by the heat transfer medium (for example, the temperature difference between the bearing contact portion of the spindle and the cooling fins). Is about 25 ° C., the heat transport amount is about 500 W in the conventional example, but 1000 W in the present example.) And has sufficient rigidity (before forming the groove 2 a and the communication passage 2 b). Stiffness is reduced by about 20%).

The groove 2a of the inner pipe 2 is
b, the amount of the heat transfer medium in all the grooves 2a becomes uniform with the rotation, so that the spindle 1 continues to rotate stably without vibrating even during high-speed rotation. Approximately 16000r when only groove 2a is used
While the limit is about pm, the vibration does not occur even at about 25000 rpm when the communication passage 2b is formed. )be able to.

Since the inner peripheral surface of the cooling fin 3a portion of the outer tube 3 is formed in a tapered shape as described above, the liquid phase component of the heat transfer medium is shifted toward the tip with the rotation of the spindle 1. Since it is easy to move, the cycle time of heat transfer by the heat transfer medium can be shortened, and the heat transfer efficiency can be improved.

[0022]

According to the spindle of the present invention, the heat transfer medium is interposed in the groove between the inner pipe and the outer pipe.
A sufficient amount of heat transfer medium could be used while ensuring sufficient wall thickness, and efficient heat transfer was possible while having sufficient rigidity. Further, since the grooves are communicated with each other by the communication passage, the amount of the heat transfer medium in each groove becomes uniform with the rotation, so that the vibration caused by the high-speed rotation can be suppressed, and the stable rotation can be continued.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a structure of a spindle according to an embodiment of the present invention.

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

FIG. 3 is a cross-sectional view illustrating a structure of an example of a conventional spindle.

FIG. 4 is a cross-sectional view illustrating a structure of another example of a conventional spindle.

FIG. 5 is a radial sectional view of the spindle of FIG. 4;

FIG. 6 is a cross-sectional view illustrating a structure of still another example of a conventional spindle.

7 is a radial sectional view of the spindle of FIG. 6;

[Explanation of symbols]

 Reference Signs List 1 spindle 2 inner tube 2a groove 2b communication passage 3 outer tube 3a cooling fin 3b introduction tube 4 holding tube 23a to 23c bearing

Claims (3)

[Claims] 1. A spindle which is driven to rotate while holding a base end of a tool at a tip end, wherein a groove holding a base end of the tool at a tip end and extending longitudinally along an axial direction is an outer peripheral surface. A plurality of inner tubes formed at predetermined intervals along the circumferential direction, and fitted on the outer peripheral surface of the inner tube so as to shield the groove and the outside of the inner tube, and a bearing is provided near the tip of the outer peripheral surface. And a heat transfer medium inserted in the groove. 2. The spindle according to claim 1, wherein a communication passage for communicating the groove of the inner pipe is formed in the inner pipe. 3. An inner peripheral surface of the outer tube is tapered so that an inner diameter of a portion of the outer tube that comes into contact with the coolant becomes smaller toward the base end. 3. The spindle according to 1 or 2.