JPH1133877A - Spindle cooling mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To cool a spindle efficiently without generating a temp. distribution by cooling the spindle uniformly as much as practicable using a refrigerant such as water, oil, etc. SOLUTION: A cylindrical cover 3 is liquid-tightly adhered to the outside surfaces of a motor 1 and bearing 2 which are coupled together. On the inside surface of the cover, two lines of grooves 31 and 32 are provided in such a way as adjoining parallel with each other. The grooves 31 and 32 cover the whole circumference of the cover 3 in reversals at the two ends of the cover 3. A refrigerant flows in the grooves 31 and 32 so that the flowing directions in the two grooves are opposite.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling mechanism for cooling a spindle by flowing a cooling medium into a flow passage formed in a housing of the spindle.

[0002]

2. Description of the Related Art A spindle is generally composed of a motor and a bearing for rotatably and immovably supporting a drive shaft of the motor. In the spindle configured as described above, electric power supplied when driving the motor is converted into heat by a coil in the motor, and frictional heat is generated by friction with a drive shaft in a bearing.
The heat generated due to such a cause also causes the shape of each part of the spindle to be deformed and deteriorates the rotational accuracy of the spindle, so that it must be effectively removed.

Conventionally, various cooling mechanisms for removing the heat generated in the spindle have been proposed, but the conventional cooling mechanisms are roughly classified into an air cooling system and a water cooling / oil cooling system.
Among these, the air cooling system improves the heat radiation efficiency from the outer peripheral surface of the housing by attaching a fin-shaped projection member to the outer peripheral surface of the housing of the spindle or processing the outer peripheral surface shape of the housing itself into a fin shape. Things.

On the other hand, in the water cooling / oil cooling system, as shown in FIG. 4, a series of spiral grooves 101 extending from one end to the other end of the housing 100 of the spindle are formed on the outer peripheral surface of the housing. As shown in (1), the spiral groove 101 is covered by covering the outer periphery of the housing 100 with a cover 102 to form the spiral groove 101 as a series of flow paths. Then, water or oil as a cooling medium cooled by a radiator (not shown) is caused to flow through a series of channels configured as described above to remove heat generated in the spindle.

[0005]

However, the cooling mechanism using the conventional air cooling system cannot improve the cooling efficiency so much, and is not suitable for a high-rotation type spindle which generates a large amount of heat.

On the other hand, in a conventional cooling mechanism using a water-cooling / oil-cooling system, there is only one flow path, and a cooling medium flows from one end of the housing to the other end in one way. Therefore, the cooling medium is still cold near the entrance of the flow path, so that the cooling efficiency is good, whereas the cooling medium is already hot near the exit of the flow path, so that the cooling efficiency is poor. Due to such a difference in cooling efficiency, a temperature distribution occurs in which the other end of the spindle is hotter than the one end. This temperature distribution increases as the heating value of the spindle increases, causing distortion of the spindle due to the difference in the amount of expansion.

[0007] Such a distortion of the spindle, for example,
This has a serious adverse effect on a mechanism with high dimensional accuracy between components, such as a hydrostatic air bearing type spindle with a gap between the shaft and the bearing of only about 10 μm. That is, in a portion where the temperature is high, the spindle shaft or the housing thermally expands, and the assembling dimensions are deviated, which causes deterioration of the rotation accuracy of the spindle.

The present invention has been made in view of the above-mentioned problems in the prior art, and the spindle is cooled as uniformly as possible by a cooling medium such as water or oil so that the spindle can be cooled without causing a temperature distribution. It is an object to provide a cooling mechanism of a spindle that can efficiently cool the spindle.

[0009]

The present invention has the following features to attain the object mentioned above. That is, claim 1
The described invention is a cooling mechanism for a spindle that rotationally drives a shaft, wherein a plurality of flow paths adjacent to each other are disposed over a predetermined area of an outer peripheral surface of the spindle, and a plurality of flow paths of the plurality of flow paths are provided. It is characterized by comprising cooling medium introduction means for introducing a cooling medium into each of the flow paths so that the directions of the flow inside the adjacent ones are opposite to each other.

With this configuration, the average temperature at each position of the cooling medium flowing through the flow passages adjacent to each other becomes substantially equal. Therefore, in the area where each flow path is provided, the outer peripheral surface of the spindle is uniformly cooled.

Each of the flow paths may be laid on the outer peripheral surface of the spindle, or may be embedded below the surface of the outer peripheral surface of the spindle. The total number of channels is 2
The number of cooling mediums may be three or more, and the direction of the flow of the cooling medium between adjacent ones may be reversed. In addition, it is desirable that the respective channels be parallel to each other because the cooling efficiency is more averaged, but the channels may have a slight inclination.

[0012] The second aspect of the present invention is specified by the fact that the plurality of flow paths of the first aspect are arranged in parallel with each other. The invention according to claim 3 is specified by the fact that the plurality of flow paths according to claim 1 or 2 are disposed so as to make a round around the spindle while reciprocating along the axial direction of the spindle. .

According to a fourth aspect of the present invention, the spindle according to any one of the first to third aspects is covered with a cylindrical cover in a liquid-tight manner, and the plurality of flow paths are formed in grooves on an inner peripheral surface of the cover. It is specified by being formed as.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of a spindle A according to an embodiment of the present invention, and FIG.
FIG. 2 is a longitudinal sectional view taken along line -II. As shown in each of these figures, the spindle A has a columnar shape as a whole, and the inside thereof is composed of a motor unit 1 and a hydrostatic bearing unit 2.

The motor unit 1 includes a cylindrical housing 1 having a bottom.
1, an excitation coil 12 fixed to the inner surface of the housing 11, a drive shaft 13 supported coaxially with the center axis of the housing 11, and an armature 14 mounted on the outer peripheral surface of the drive shaft 13. You.

On the other hand, the bearing portion 2 has a cylindrical housing 21 having the same outer diameter as the housing 11 of the motor portion 1.
Porous bearing members 22, 22 fitted from both front and rear ends of the housing 21, and the respective porous bearing members 22, 2
A shaft 23 inserted in bearing holes 22a formed at the center of the shaft 2; a disk fixed to an end of the shaft 23 on the motor unit 1 side and directly connecting the drive shaft 13 of the motor unit 1 to the shaft 23; Shaped inner collar 25, and
It is composed of a disk-shaped outer flange 24 fixed to the other end of the shaft 23 and connected to an object to be rotated.

The inner peripheral surface of the housing 21 has a small diameter in three stages from the front and rear ends toward the center. That is,
At the center of the housing 21, the inner peripheral surface of the housing 21 has a central space 21 a having a diameter larger than the outer diameter of the shaft 23.
Is formed. On both sides of the central space 21a, the inner peripheral surface of the housing 21 forms middle spaces 21b, 21b having a diameter slightly larger than the inner diameter of the central space 21a. Further, both ends of the inner peripheral surface of the housing 21 are formed in an end space 21 having a larger diameter than the two middle spaces 21b, 21b.
c, 21c.

Each of the porous bearing members 22, 22 has a male screw formed on an outer peripheral surface thereof which is screwed to a female screw formed on an inner peripheral surface of an end space 21c of the housing 21, and a shaft of the end space 21c. A flange portion 22b that is slightly thinner than the length in the direction, and reaches the central space 21a when the flange portion 22b is screwed into the end space 21c, and has a diameter slightly smaller than the inner diameter of the middle space 21b and slightly larger than the inner diameter of the central space 21a. And a sleeve portion 22c having an outer diameter. Further, at the center of each porous bearing member 22, at a position where this flange portion 22 b is coaxial with the housing 21 when screwed into the end space 21 c, the diameter is slightly smaller than the inner diameter of the central space 21 a of the housing 21. A bearing hole 22a slightly larger in diameter than the outer diameter of the shaft 23 is formed through the shaft.

The shaft 23 has a cylindrical shape slightly longer than the axial length of the housing 21. Each collar 2
4 and 25 have the same outer diameter as the flange portions 22b and 22b of the respective porous bearing members 22 and 22 with a slight clearance between the outer end surfaces of the respective porous bearing members 22 and 22. Are facing each other.

The motor unit 1 and the bearing unit 2 are connected to the drive shaft 13 of the motor unit 1 and the inner flange 25 of the bearing unit 2 coaxially, and the housing 11 of the motor unit 1 and the bearing unit. The two housings 21 are coaxially and airtightly connected. In such a connected state, the outer peripheral surface of the housing 11 of the motor unit 1 and the bearing unit 2
Is flush with the outer peripheral surface of the housing 21. The motor unit 1 and the bearing unit 2 connected in this manner are inserted into a cylindrical cover 3.

The cover 3 has an inner diameter that is the same as the outer diameter of the housing 11 of the motor unit 1 and the housing 21 of the bearing unit 2. The outer peripheral surfaces of the housings 11 and 21 and the inner peripheral surface of the cover 3 are bonded in a liquid-tight manner.

On the inner peripheral surface of the cover 3, two grooves 31 and 32 are formed in advance. Hereinafter, the shapes of these two systems of grooves 31 and 32 will be described in detail.
FIG. 3 is a developed view showing an inner surface of the cover 3 by cutting the cover 3 along a two-dot chain line III in FIG. As shown in FIGS. 2 and 3, each of the grooves 31 and 32 is a bottomed groove having a square cross section, and has an injection hole (circular hole) 31 at the start end thereof.
a, 32a, and penetrates the outer peripheral surface of the cover 3,
At the terminal end, it penetrates through the outer peripheral surface of the cover 3 through discharge holes (circular holes) 31b and 32b. In addition, each groove 3
1, 32 are disposed adjacent to each other in the entire area thereof, and advance in the circumferential direction by about 1/8 turn in the vicinity of the edge of the cover 3 on the bearing portion 2 side (hereinafter referred to as the bearing side edge 3a). 90 in the direction parallel to the center axis l of the spindle A.
And turns parallel to the central axis l to near the edge of the cover 3 on the motor unit 1 side (hereinafter, referred to as a motor-side edge 3b).
Bend 90 degrees in the circumferential direction of spindle A, about 1/4
The circumference advances in the circumferential direction, turns 90 degrees in a direction parallel to the center axis 1 of the spindle A, advances in parallel with the center axis 1 to near the bearing side edge 3a, and moves 90 degrees in the circumferential direction of the spindle A.
Turn once and proceed in the circumferential direction for about 1/8 turn. The above progress is 4
By repeating the cycle, the grooves 31 and 32 are arranged over the entire inner peripheral surface of the cover 3.

Since the grooves 31 and 32 are provided in this manner, the starting ends of the grooves 31 and 32 (injection holes 31a and 32).
a) and the end portions (discharge holes 31b, 32b)
Are arranged together near the bearing side edge 3a. Specifically, at the position closest to the bearing side edge 3a of the cover 3,
The starting end (injection hole 32a) of the second groove 32 and the second groove 32
(Discharge hole 32b) are arranged side by side in the circumferential direction. Also, the starting end of the second groove 32 (injection hole 32a)
The end portion (discharge hole 31b) of the first groove 31 is adjacent to the motor side edge 3b side, and the motor side end edge 3b side of the end portion (discharge hole 32b) of the second groove 32. Is adjacent to the start end (injection hole 31a) of the first groove 31. As can be seen from the positions of the start end (injection holes 31a, 32a) and end end (discharge holes 31b, 32b) of these grooves 31, 32, the grooves 31, 32 which were adjacent to each other in parallel.
, The direction of the flow inside (the direction from the start end to the end) is opposite.

Each of the grooves 31 and 32 thus configured is
When the motor unit 1 and the bearing unit 2 are inserted into the cover 3,
Since the outer surface of the housing 11 of the motor unit 1 and the outer surface of the housing 21 of the bearing unit 2 are covered, a series of two channels having a square cross section are formed.

As shown in FIG. 1, an injection pipe 91 is removably fitted around the outer periphery of the cover 3 to allow the injection pipe 91 to communicate with the injection hole 31a of the first groove 31. The injection plug 5 and the discharge pipe 92 are removably inserted, and the first discharge plug 6 and the injection pipe 91 for allowing the discharge pipe 92 to communicate with the discharge hole 31b of the first groove 31 are removably inserted. The second injection plug 7 for communicating the injection pipe 91 with the injection hole 32a of the second groove 32, and the discharge pipe 92 are detachably inserted into the discharge pipe 92 and the discharge hole of the second groove 32. The second discharge plug 8 for communicating with the second discharge plug 32b is mounted.

The above-described injection pipes 91, 91 are united in one piece on the way and connected to the liquid supply port 9a of the cooling unit 9. Further, each of the above-mentioned discharge pipes 92, 92
Are connected together to the recovery port 9b of the cooling unit 9 on the way.

The cooling unit 9 is composed of a pump section and a radiator section, and sends out water or oil (hereinafter, referred to as a cooling medium) pressurized in the pump section from the liquid feed port 9a into the injection pipe 91 and discharges the same. The high-temperature cooling medium returned from the pipe 92 to the recovery port 9b is cooled by exchanging heat in the radiator section, and is again sent out from the liquid feeding port 9a into the injection pipe 91 by the pump section.

The operation of the spindle A including the cooling mechanism configured as described above will be described below. First, each air space 21 of the housing 21 is moved by an air pump (not shown).
Compressed air is introduced into air chambers formed between the porous bearing members 22 and 22 and the end spaces 21c and 21c. Then, since the pressure in the air chamber becomes higher than the atmospheric pressure, the air in the air chamber is released from the porous chamber bearing member 2.
The gas passes through the porous chamber bearing members 22, 22 through the pores in the holes 2, 22, and is sprayed from the outer end surfaces thereof to the respective flange portions 24, 25, and is sprayed from the inner surfaces of the bearing holes 22a, 22a to the outer peripheral surface of the shaft. The air thus blown out from between the outer end surfaces of the porous chamber bearing members 22 and 22 and the flanges 24 and 25, and also blows into the central space 21a and then to the outside through an exhaust port (not shown). Blow out. Since such an air flow is generated, each flange portion 24, 25 and each perforated chamber bearing member 2 are caused by the pressure.
The shaft 23 is kept coaxial with the outer end surfaces of the porous chambers 2 and 22 at a constant interval, and the shaft 23 is floated in the bearing holes 22a and 22a of the porous chamber bearing members 22 and 22.

Next, drive power is supplied to each of the excitation coils 12 and the armatures 14 of the motor unit 1. Then, the drive shaft 13 rotates in a predetermined direction, and at the same time, the shaft 23 connected to the drive shaft 13 rotates while maintaining a floating state in the bearing portion 2.

While the drive shaft 13 and the shaft 23 are rotating as described above, the coils 12 and 14 of the motor unit 1 generate heat changed from the drive electric power, and the sliding contact of the motor unit 1 is performed. Friction heat due to sliding contact is generated from the portion, and friction heat due to friction with air is generated from the air flow path in the bearing portion 2.

When the pump unit of the cooling unit 9 is driven in order to cool the spindle A by removing the heat generated in this way, as described above, the cold cooling performed in the radiator unit in the cooling unit 9 is performed. The medium is supplied via the injection pipe 91 through the injection ports 31a, 31a of the respective grooves 31, 32.
32a. The cooling medium injected into the grooves 31 and 32 in this manner flows through the grooves 31 and 32 toward the respective ends. While flowing through the grooves 31 and 32 in this manner, the cooling medium absorbs the heat generated at each part in the spindle A and becomes hotter.

Here, as described above, each groove 3
1 and 32 are arranged adjacent to each other in parallel, but the inlets 31a and 32a and the outlets 31b. The position of 32b, that is, the direction in which the cooling medium flows is opposite to each other.
That is, when the spindle A is viewed from the bearing portion 2 side (the direction of FIG. 1), the cooling medium flowing through the first groove 31 flows clockwise, and the cooling medium flowing through the second groove 32 flows counterclockwise. As the cooling medium flows through the grooves 31 and 32 and becomes hotter, the cooling efficiency of the cooling medium decreases, but the flow direction of the cooling medium in each of the grooves 31 and 32 is reversed. Therefore, the spindle A is uniformly cooled in the entire circumferential direction. That is, in the vicinity of the start end of the first groove 31, the cooling medium in the first groove 31 is cold and has high cooling efficiency, but the cooling medium in the second groove 32 is hot and has low cooling efficiency. In the middle portion between the grooves 31, 32, the cooling medium in the first groove 31 and the cooling medium in the second groove 32 are both at medium temperatures, so that the cooling efficiency is also medium. In the vicinity of the end of the first groove 31, the first
The cooling medium in the groove 31 is hot and has low cooling efficiency, but the cooling medium in the second groove 32 is cold and has good cooling efficiency. As a result, cooling is uniformly performed over the entire outer peripheral surface of the spindle A.

The cooling medium heated by passing through the grooves 31 and 32 is returned to the cooling unit 9 through the discharge pipes 92 from the respective discharge ports 31b and 32b. The hot cooling medium thus returned is cooled in the radiator section in the cooling unit 9 and becomes cold again.

In this embodiment, two grooves 31, 32 are provided.
Is formed so as to go around the cover 3 while reciprocating between the bearing side edge 3a of the cover 3 and the motor side edge 3b, but from the bearing side edge 3a of the cover 3 to the motor side edge 3b.
May be spirally formed.

[0035]

According to the spindle cooling mechanism of the present invention configured as described above, the spindle is cooled by the cooling medium such as water or oil flowing in the flow path disposed over a predetermined area of the spindle. The spindle can be cooled efficiently. Further, since the flow directions of the cooling medium in the plurality of flow paths arranged adjacent to each other are made opposite to each other, the entire spindle can be cooled as uniformly as possible.

[Brief description of the drawings]

FIG. 1 is a perspective view of a spindle incorporating a cooling mechanism according to an embodiment of the present invention.

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

FIG. 3 is an exploded view showing an inner surface of the cover by cutting the cover along a two-dot chain line III in FIG. 1;

FIG. 4 is a perspective view showing a state in which a cover is removed from a conventional spindle.

FIG. 5 is a perspective view of a conventional spindle.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Motor part 2 Bearing part 3 Cover 9 Cooling unit 11 Housing 13 Drive shaft 22 Housing 23 Shaft 31 First groove 32 Second groove 91 Injection pipe 92 Discharge pipe

Claims (4)

[Claims] 1. A cooling mechanism for a spindle that rotationally drives a shaft, comprising: a plurality of flow paths adjacent to each other, each of which is disposed over a predetermined area of an outer peripheral surface of the spindle; A cooling mechanism for a spindle, comprising: cooling medium introduction means for introducing a cooling medium into each of the flow paths so that the flow directions inside the adjacent ones are opposite to each other. 2. The spindle cooling mechanism according to claim 1, wherein said plurality of flow paths are arranged in parallel with each other. 3. The spindle cooling mechanism according to claim 1, wherein the plurality of flow paths are disposed so as to make a round around the spindle while reciprocating along the axial direction of the spindle. . 4. The apparatus according to claim 1, wherein said spindle is liquid-tightly covered by a cylindrical cover, and said plurality of flow paths are formed as grooves on an inner peripheral surface of said cover. 3. The cooling mechanism for a spindle according to any one of 3.