JPH0694100B2 - Spindle cooling structure - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a cooling structure for a spindle used in a machine tool such as a machining center, and more particularly to a spindle cooling structure capable of efficiently cooling the spindle.

[Prior Art] In a conventional spindle cooling structure, a housing that rotatably supports the spindle for spindle is cooled in order to prevent thermal displacement due to temperature rise of the spindle for spindle. The cooling structure in this case includes oil mist, oil air, electronic cooling, and the like, and jet lubrication is a method for cooling while lubricating the bearing.

[Problems to be solved by the invention]

However, in the above conventional spindle cooling structure, since the housing is cooled, the outer ring of the rolling bearing fitted in the housing is also cooled, and the temperature difference between the inner and outer rings of this rolling bearing is also cooled. Is larger, leading to an increase in preload, which is a conflict with increasing speed, and even if the housing is cooled, the spindle for spindle is indirectly cooled.
There is a problem that the cooling efficiency with respect to thermal displacement is reduced.

In addition, electronic cooling and jet lubrication have problems that the structure is complicated and the size is large, and the equipment cost is high.

Further, although the lubrication method of oil mist, oil air, etc. is a method aiming at the effect of air cooling, it cannot be expected to have a great cooling effect.

Therefore, the present invention has been made by paying attention to the problems of the above-mentioned conventional example, and by directly cooling the spindle for spindle, it is possible to improve the cooling efficiency of the spindle for spindle with a simple structure. It is intended to provide a structure.

[Means for solving problems]

In order to solve the above problems, the present invention relates to a cooling structure of a spindle in which a spindle is rotatably supported, and a spacer having fins formed on the outer peripheral surface is fitted to the outer peripheral surface of the spindle. A coolant passage is formed between the fin of the spacer and the housing facing it,
An air seal portion is provided on both sides of the coolant passage.

[Action]

According to the present invention, the fin is formed on the outer peripheral surface of the spindle, and the coolant passage is formed between the fin and the facing housing, so that the coolant comes into direct contact with the fin. Since the spacer formed with and the spindle are fitted and integrated with each other, the spindle can be directly cooled to improve its cooling efficiency.

Further, by providing the air seal portions on both sides of the coolant passage, it is possible to reliably prevent the coolant from leaking.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a vertical sectional view showing an embodiment of the present invention, and FIG. 2 is an enlarged sectional view of a main part thereof.

In the figure, 1 is a cylindrical housing, and 2 is a spindle for spindle which is rotatably held in the housing 1.

The outer ring 3a of the ball bearing 3 and the outer ring 4a of the roller bearing 4 are fitted inside the housing 1 at the left and right ends of the inner peripheral surface thereof, and the coolant passage 5 is formed at the center between the bearings 3 and 4. There is.
An inner ring spacer 6 and an outer ring spacer 7 are interposed between the ball bearings 3. An oil / air supply passage 8 for supplying oil / air as a lubricant to the bearings 3 and 4 is bored inside the housing 1, and a coolant supply passage 9I and a coolant communicating with the coolant passage 5 are provided. The discharge path 9O is provided. Further, on the outer peripheral surface of the housing 1, spiral grooves 10 for giving a cooling effect by a coolant are engraved at a predetermined pitch, and the coolant passes through the space between the housing mounting bracket and the spiral groove 10 of the housing. The cooling effect of the housing 1 is provided.

On the other hand, a through hole 11 is bored in the main spindle 2 and a left end portion of the through hole 11 serves as a taper-shaped tool mounting portion 12. Further, an inner ring of the ball bearing 3 is provided on the outer peripheral surface.
3b and the inner ring 4b of the roller bearing 4 are externally fitted, and the spacer 13 is integrally fixed to the center portion between the inner rings 3b and 4b of both bearings 3 and 4 so as to face the coolant passage 5 of the housing 1. Has been done.
Here, as shown in FIG. 2, the spacer 13 has a large number of cooling fins 14 formed on the outer peripheral surface thereof at positions facing the coolant passages 5, and a step portion 15 formed on the inner peripheral surface of the spacer 13. By engaging the step portion 16 formed on the outer peripheral surface of the spindle 2 for use and abutting the nut 17 that is screwed on the male screw formed on the outer peripheral surface of the spindle 2 for the right end surface, the spindle 2 for the spindle 2
Is integrally fixed to.

Air seal portions 18 and 19 formed of annular grooves are formed on the inner peripheral surface of the housing 1 and the outer peripheral surface of the spacer 13 at both positions sandwiching the coolant passage 5 and the cooling fin 14, respectively, and the annular grooves are also formed on the outer sides thereof. The air exhaust ports 20 and 21 are formed. Pressurized air is supplied to the air seals 18 and 19 through air supply passages 22 formed in the housing 1, respectively.
Similarly, an air exhaust port 23 formed in the housing 1 is connected to the air exhaust ports 20 and 21, and the air in the air exhaust ports 20 and 21 is exhausted to the outside through the air passage 23.

Incidentally, 24 is a labyrinth gap formed between the inner peripheral surface of the housing 1 and the outer peripheral surface of the spacer 13, and 25 and 26 are oil air formed on the end plates 27, 28 which are in contact with both ends of the housing 1. A supply port and a discharge port, 29 are suction pumps connected to the coolant discharge passage 9O.

Next, the operation of the above embodiment will be described. The oil air is pressure-fed to the oil air supply port 25 formed in the end plate 27 that is in contact with one end of the housing 1, so that the oil air is supplied through the oil air supply passage 8 in the housing 1 to the bearings 3, 4
The bearings 3 and 4 are fed to the position to lubricate them.

On the other hand, a coolant such as cooling oil is supplied to the coolant passage 5 through a coolant supply passage 91 formed in the housing 1,
The coolant in the cooling passage 5 is sucked and discharged by the pump 29 connected to the coolant discharge passage 9O formed in the housing 1.

By supplying the coolant to the coolant passage 5 in this way, the cooling fins 14 of the spacer 13 are cooled, and the spacer 13 and the spindle 2 for the spindle are integrally fixed. 2 will be cooled directly by the coolant.

Therefore, in this state, when a predetermined cutting tool is mounted on the tool mounting portion 12 of the spindle for spindle 2 and driven to rotate at high speed, frictional heat is generated at the bearings 3 and 4 positions or the cutting tool position according to the rotation, This is transmitted to the spindle 2 for the main shaft. However, as described above, the main spindle 2
Is cooled through the spacer 13, it is possible to reliably prevent the temperature rise of the spindle 2 for the main spindle. For this reason, it is possible to suppress the occurrence of thermal displacement due to the temperature rise of the spindle 2 for the spindle, so that the dimensions of the spindle 2 for the spindle can be maintained with high accuracy.

Further, since air seal portions 18 and 19 are formed on both sides of the coolant passage 5 and pressurized air is supplied to these air seals 18 and 19 through the air supply passage 22 formed in the housing 1, the coolant passages are formed. As a lubricant to be supplied to the bearings 3 and 4, it is possible to reliably prevent the coolant supplied to the bearing 5 from leaking to the bearings 3 and 4 through the inner peripheral surface of the housing 1 and the outer peripheral surface of the spacer 13. Coolant mixed in the oil and air of the bearing 3,
It is possible to prevent the occurrence of lubrication failure of 4. Moreover, since the supply of the coolant to the coolant passage 5 is not sent under pressure but is sucked by the pump 29 on the outlet side, the leakage of the coolant can be reduced, and the air seal portions 18 and 19 can be reduced. Along with the sealing effect, the leakage of the coolant can be prevented more reliably.

In the above embodiment, the case where the coolant passage 5 is formed on the inner peripheral surface of the housing 1 has been described, but the present invention is not limited to this, and the spacer 13 has a cooling fin 14 at the bottom.
It is also possible to form the coolant passage 5 which is a concave groove in which is formed, or to form the coolant passage in both the housing 1 and the spacer 13.

Further, the spacer 13 and the coolant passage 5 facing the spacer 13 are not limited to one set, and a plurality of sets may be provided in the axial direction of the spindle 2 for the spindle.

Further, air seal portions 1 formed on both sides of the coolant passage 5
The number of 8, 19 is not limited to one set, and a plurality of sets can be installed in series.
Further, the air discharge path 23 may be structured without this.

Furthermore, in the above embodiment, the case where the present invention is applied to the spindle for the spindle of the machine tool has been described, but the present invention is not limited to this, and may be applied to spindles that cause thermal displacement of other machines and devices. Of course, this invention can be applied.

〔The invention's effect〕

As described above, according to the present invention, in the spindle cooling structure in which the spindle is rotatably supported in the housing, the spacer having the fin formed on the outer peripheral surface of the spindle is fitted and the fin of the spacer is provided. Since the coolant passage is formed between the housing and the housing facing it, and the air seal portions are provided on both sides of the coolant passage, the entire configuration is not complicated and large, and the spindle is directly cooled. It is possible to improve the cooling effect of the spindle. Therefore, it is possible to reliably prevent deterioration of dimensional accuracy due to thermal displacement of the spindle, and it is possible to reduce the temperature difference between the inner and outer races of the rolling bearing and maintain smooth rotation without increasing preload. . Further, since the air seal portions are formed on both sides of the coolant passage, it is possible to reliably prevent the coolant supplied to the coolant passage from leaking out, and it is possible to prevent the lubrication failure of the bearing or the like adjacent to the coolant passage. It is possible to obtain an effect that it can be surely prevented from occurring.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention, and FIG. 2 is an enlarged sectional view of a main part of FIG. In the figure, 1 is a housing, 2 is a spindle for spindle, 3 is a ball bearing, 4 is a roller bearing, 5 is a coolant passage, 9I is a coolant supply passage, 13 is a spacer, 14 is a cooling fin, and 18 and 19 are It is an air seal.

Claims (1)

[Claims] 1. A cooling structure for a spindle in which a spindle is rotatably supported in a housing. A spacer having fins formed on the outer peripheral surface is fitted to the outer peripheral surface of the spindle, and the fin of the spacer is opposed to the fin. A cooling mechanism for a spindle, wherein a cooling medium passage is formed between the cooling medium passage and an inner surface of the housing, and air seal portions are provided on both sides of the cooling medium passage.