JPH0631585A - Cooling structure for main spindle device - Google Patents

Abstract

PURPOSE:To provide the coolant structure of a main spindle device which can be cooled uniformly and efficiently without increasing the quantity of parts and without being restrained in design. CONSTITUTION:A cooling structure for a main spindle device which is equipped with a spindle head (housing) 1 and a main spindle 3 which is axially supported on the spindle head through a roller bearing outer cylinder 9 is constituted. In this case, a spiral groove 16 is formed on the outer surface of the spindle 3, and the space formed from the spiral groove 16 and the inner surface of a bearing inner cylinder 11 is used as coolant flow passage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling structure for a spindle device used for cooling a spindle portion of a machine tool, for example.

[0002]

2. Description of the Related Art For example, in a machine tool, a main shaft is rotatably supported by a housing via rolling bearings. Since this bearing section generates heat by rotation, it is necessary to suppress the temperature rise of the spindle by eliminating this heat and minimize the error due to thermal displacement. Conventionally, as a structure for absorbing and discharging heat generated from a bearing inner cylinder, (1) a structure in which a flow passage is provided axially in a main shaft near a bearing to flow a cooling liquid (see Japanese Patent Laid-Open No. 64-87130). 2) A structure in which a sleeve is inserted and arranged in the main shaft, and a flow path is provided between the outer surface of the sleeve and the inner surface of the main shaft to flow a cooling liquid (see Japanese Utility Model Laid-Open No. 64-50036). (3) Sleeve outside the main shaft There is known a structure in which a cooling fluid is flowed between the inner surface of the sleeve and the outer surface of the main shaft (see Japanese Utility Model Laid-Open No. 64-12753).

[0003]

However, the above (1)
In the conventional structure in which the flow path is provided in the main shaft as described above, there is a problem that efficiency is poor because the bearing is indirectly cooled.
Moreover, since it is difficult to uniformly provide the flow path in the main shaft, there is a problem that uniform cooling cannot be performed.

When a sleeve is provided inside or outside the main shaft as in (2) or (3) above, maintaining the inner diameter increases the outer diameter of the entire main shaft including the sleeve.
On the contrary, there is a problem in that there are restrictions in design such that the inner diameter becomes smaller when the outer diameter dimension is maintained, and the number of parts increases and the cost becomes higher.

The present invention has been made in view of the above-mentioned conventional circumstances, and provides a cooling structure for a spindle device capable of cooling uniformly and efficiently without being restricted by design or increasing the number of parts. Is intended.

[0006]

According to a first aspect of the present invention, there is provided a cooling structure for a spindle device comprising a housing and a spindle supported by the housing via a rolling bearing, the inner cylinder of the bearing and the spindle. It is characterized in that a groove is formed on at least one of the fitting surfaces of and, and the space formed by the groove and the mating fitting surface serves as a cooling liquid flow path.

The invention according to claim 2 is characterized in that the inner cylinder is formed with a communication hole for communicating the cooling flow path with a portion between the inner cylinder and the outer cylinder of the bearing.

[0008]

According to the cooling structure of the spindle device according to the present invention, the cooling liquid circulates through the cooling liquid passage formed in the fitting surface between the spindle and the bearing inner cylinder, and at this time, the cooling liquid is generated from the bearing inner cylinder. It absorbs the heat generated and removes it outward.

As described above, in the present invention, since the cooling liquid flow path is formed on the fitting surface between the outer circumference of the main shaft and the inner cylinder of the bearing, the cooling liquid comes into direct contact with the inner cylinder of the bearing. As a result, the cooling efficiency is improved as compared with the conventional indirect cooling structure.

Further, since the cooling liquid flow path is formed by utilizing the inner peripheral surface of the inner cylinder of the bearing which has been conventionally provided without using a sleeve or the like, there is a design restriction on the outer diameter and the inner diameter of the main shaft. Never. Further, since the sleeve is not necessary, it is not necessary to increase the number of parts, so that it can be constructed at a low price.

Further, according to the second aspect of the present invention, since a part of the cooling liquid is supplied into the bearing through the communication hole by the centrifugal force, the cooling effect of the bearing portion can be further enhanced. In addition, because the cooling liquid flow path is made to communicate with the bearing through the communication hole,
When so-called underrace lubrication suitable for high-speed rotation of the main shaft is also used by directly lubricating the bearing rolling surface, it is not necessary to provide a new lubricating oil passage.

[0012]

Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 and 2 are views for explaining a cooling structure of a spindle device in a machine tool according to a first embodiment of the present invention. FIG. 1 is an enlarged cross-sectional view of an essential part near a cooling liquid flow path,
FIG. 2 is a sectional view of the entire spindle device.

In FIG. 1, reference numeral 1 is a spindle head (housing) which is movably supported in a vertical direction by a column (not shown), and 2 is a spindle cylinder inserted and fixed in the spindle head 1.
Reference numeral 3 denotes a main shaft rotatably supported by a main spindle head 1 via a bearing unit 4 and an upper bearing 5.

The main shaft 3 has a cylindrical shape, and a taper hole 3a into which a tool T is mounted is formed at a lower end portion of the main shaft 3. The tool T is locked or unlocked via a collet 6 inside. The drawbar 7 is inserted and arranged. Further, the spindle 3 is rotationally driven by a drive motor 8 arranged in the spindle head 1.

The bearing unit 4 is formed by uniting four ball bearings, and includes four rolling bearing outer cylinders 9 arranged at intervals of two and outer members of both upper and lower sets. It is composed of a spacer 10 sandwiched between the cylinders 9, a bearing inner cylinder 11 common to both upper and lower sets, and a large number of balls 12 installed between the inner cylinder 11 and each outer cylinder 9. There is.

Here, the spacer 10 is configured to apply a preload between the outer cylinders 9 and the balls 12 by axially pressing the outer cylinders 9 of the upper and lower sets. . In this case, in the adjustment of the preload, the spacer length is corrected, but in order to facilitate the correction work and the assembling work, the spacer 10 is divided into two along the dividing surface passing through the axial center. ing. The outer cylinder 9 is axially clamped and fixed by a front cover 13 fixed to the lower surface of the spindle cylinder 2, whereby the preload is applied.

The common inner cylinder 11 is formed by integrating a normal inner cylinder for each bearing with a spacer provided between the inner cylinders. It has a length of The inner cylinder 11 is axially sandwiched and fixed by a fixing member 14 and a fixing nut 15 of the bearing inner cylinder.

A spiral groove 16 is formed on the outer periphery of the main shaft 3 in a range where the inner cylinder 11 is mounted. By fitting and mounting the inner cylinder 11, the main shaft 3 and the inner cylinder 11 are fitted.
A cooling liquid passage is formed on the mating surface with. The lower end and the upper end of the spiral groove 16 are respectively provided with cooling liquid passages 3a and 3b formed in the main shaft 3 in the axial direction and cooling liquid passages 14a and 14b formed in the fixing member 14 in the radial direction, respectively.
A ring groove 17 formed in the fitting surface between the fixing member 14 and the spindle cylinder 2 is communicatively connected. Also, this ring groove 1
7 and 17 are led out to a coolant supply port 18 and a discharge port 19 through the passages of the spindle cylinder 2 and the spindle head 1. In addition, 20 is an O-ring for preventing the coolant from leaking from each boundary, 21
Is a coolant supply port, 22 is a coolant discharge port, and 23 is a main cylinder 2
And a spindle head 1, which is a cooling liquid flow path communicating with the supply port and the discharge port. Further, 24 is an air passage for an air seal, in which the cooling liquid flows from the ring groove 17 to the fixing member 1.
This is for preventing leakage to the boundary portion between the spindle 4 and the spindle cylinder 2.

Next, the function and effect of the apparatus of this embodiment will be described. The cooling liquid whose temperature is controlled outside the main spindle 3 is supplied from the cooling liquid supply port 18 of the main spindle head 1 at a constant pressure, passes through the passages of the main spindle head 1 and the main spindle cylinder 2, and then the main spindle cylinder 2 and the fixing member. The whole of the ring groove 17 at the boundary with 14 is filled, and then supplied to the spiral groove 16 through the cooling liquid passage 14a of the fixed member 14 and the cooling liquid passage 3a in the main shaft 3. This cooling liquid cools the bearing inner cylinder 11 along the spiral groove 16, passes through the cooling liquid passages 3b and 14b, and the cooling liquid discharge port 1
Emitted from 9. In addition, compressed air is supplied to the boundary portion between the fixed member 14 and the main cylinder 2 by the air passage 24
Prevent leakage of cooling fluid.

As described above, in this embodiment, the cooling liquid is the main shaft 3
Also, since the heat flows from the bearing inner cylinder 11 while directly contacting it, the heat from the bearing inner cylinder 11 can be efficiently absorbed and discharged to the outside, and a higher cooling effect can be achieved as compared with the case of conventional indirect cooling. You can

Further, in this embodiment, the spiral groove 16 is formed on the main shaft 3.
Since the space surrounded by the groove 16 and the bearing inner cylinder 11 is used as a cooling liquid flow path, there is no need to change the inner diameter or the outer diameter of the main shaft 3 as in the case of using a conventional sleeve. There are no design restrictions.

Further, in this embodiment, since the flow path is formed by utilizing the inner surface of the bearing inner cylinder 11, it is possible to enhance the cooling effect without increasing the number of parts, and the cost is not increased.

Furthermore, since the inner cylinder 11 has a tubular shape over the entire length of the bearing unit 4, even if the cooling liquid is passed through the inner cylinder 11, the cooling liquid does not leak into the bearing. Therefore, a low-viscosity cooling liquid having a good heat exchange rate can be used.

FIG. 3 shows a second embodiment according to the invention of claim 2, in which the same reference numerals as those in FIG. 1 designate the same or corresponding parts. In this embodiment, a communication hole 11a is formed in the ball 12 portion of the inner cylinder 11, and the communication hole 11a communicates the spiral groove 16 with the bearing inside A. Further, the inside A of the bearing is provided with a spacer 10 and a discharge passage 1 formed in the main barrel 2.
It is connected to the outlet 25 through 0a and 2a.

In this embodiment, lubricating oil is used as the cooling liquid, and a part of this cooling liquid is supplied from the spiral groove 16 to the ball 12 through the communication hole 11a, and then the discharge passages 10a and 2a. It passes through and is discharged to the outside. In addition,
It is desirable that the discharge passage 10a be provided at the lowermost portion of the main shaft so as not to collect the lubricating oil, or that the lubricating oil be sucked.

In this embodiment, since the cooling liquid is introduced into the bearing, the bearing portion can be cooled more effectively, the lubricating oil can be reliably supplied to the bearing, and when so-called underrace lubrication is also used. , It is not necessary to provide a new lubricating oil passage.

In each of the above embodiments, the spiral groove 16 is formed in the main shaft 3, but the spiral groove may be formed in the bearing inner cylinder 11, or the main shaft 3 and the bearing inner cylinder 11 may be formed. It may be formed so as to face both, and may be used as a cooling liquid flow path.

Further, the shape of the flow path of the cooling liquid is not limited to the spiral groove 16, and it is possible to provide a plurality of grooves in the axial direction, for example.

Furthermore, the case where the inner cylinder 11 is the one in which the inner ring and the spacer are integrated has been described, but this does not necessarily have to be integrated. In this case, a seal member will be provided.

The scope of application of the present invention is not limited to the machine tool in the above-mentioned embodiment, and the point is that any main spindle device in which the main spindle is supported by the housing through rolling bearings is essential. Applicable.

Here, as an application example of the present invention, it is conceivable to further form the cooling liquid flow path as described above on the fitting surface between the bearing outer cylinder and the housing to allow the cooling liquid to pass therethrough. By doing so, cooling can be performed more efficiently.

[0032]

As described above, according to the cooling structure of the spindle device of the present invention, the cooling liquid directly contacts the outer surface of the spindle and the inner surface of the bearing inner cylinder, so that the cooling efficiency can be improved. Further, since there is no need to provide a sleeve or the like, there are no restrictions in designing the outer diameter and the inner diameter of the spindle, and there is an effect that the number of parts is reduced and an increase in cost can be avoided.

Further, according to the second aspect of the invention, since the communication hole for introducing the cooling liquid is formed inside the bearing, the cooling effect can be improved and a new lubricating oil passage is not required when so-called underrace lubrication is also used. There is an effect that can be.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part for explaining a cooling structure of a spindle device of a machine tool according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing the overall configuration of the first embodiment.

FIG. 3 is a sectional view showing a second embodiment of the present invention.

[Explanation of symbols]

 1 Spindle Head (Housing) 3 Spindle 9 Rolling Bearing Outer Cylinder 11 Bearing Inner Cylinder 11a Communication Hole 16 Helical Groove

Claims (2)

[Claims] 1. A cooling structure for a spindle device comprising a housing and a spindle supported by a rolling bearing in the housing, wherein a groove is provided on at least one of the fitting surfaces of the inner cylinder of the bearing and the spindle. A cooling structure for a spindle device, characterized in that a space formed by the groove and a mating mating surface is used as a cooling liquid flow path. 2. The cooling structure for a spindle device according to claim 1, wherein the inner cylinder is formed with a communication hole for communicating the cooling liquid flow path with a portion between the inner cylinder and the outer cylinder of the bearing.