JP2010016993A - High-speed spindle motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spindle motor which maximizes the output per unit volume while reducing the size and weight as much as possible by forming a cooling structure for minimizing a temperature rise of a stator coil which determines the limit of output from the spindle motor. <P>SOLUTION: In a high-speed spindle motor, a compressed air supplied from a joint 26 passes through gaps g1, g2, g3 and g4 and reaches a gap g5 in the outer circumferential surface of a stator coil 4. The gap g5 is formed between the stator stacks 2 over the total length of the stator coil 4, and the compressed air takes Joule's heat of I<SP>2</SP>R generated from the stator coil 4, thus cooling the stator coil 4 directly. The compressed air passing through the gap g5 is discharged to the outside through a gap g6 provided in the front flange 7. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a spindle motor that obtains a small and high output by efficiently air-cooling a stator coil of a spindle motor for driving a tool at high speed in a machine tool.

A spindle motor used in a machine tool or the like needs to be rotated at an extremely high rotational speed, and therefore, a cooling structure for radiating heat generated is required.
Patent Document 1 is a conventional example that proposes a device that can suppress an increase in temperature in a housing of a spindle motor and reduce adverse effects due to heat.
This is because the passage between the stator and the rotor and the air passage between the bearing and the shaft are provided, and the air is supplied from the air supply passage. It removes the heat generated by the large rotational load on the surface.
JP 2002-301636 A

In order to increase the rotational speed up to the output limit of the spindle motor, a large current must be passed through the stator coil. For this purpose, it is necessary to suppress the temperature rise of the stator coil.
In the conventional spindle motor cooling structure, the heat generated by the stator coil cannot be efficiently released, and as a result, a small-sized spindle motor cannot be realized.

  The present invention solves the above problem, and its purpose is to maximize the output per unit volume by forming a cooling structure that minimizes the temperature rise of the stator coil that determines the limit of the output of the spindle motor. An object of the present invention is to provide a spindle motor that is as small and light as possible.

In order to achieve the above object, a first aspect of the present invention is a spindle motor configured by incorporating a rotor assembly in a stator assembly, wherein the stator assembly comprises a housing / stack assembly and a coil / hub assembly. The housing / stack assembly forms a stator stack on the inner periphery of a cylindrical housing, and the coil / hub assembly has one end of a coreless type stator coil having an outer diameter smaller than the inner diameter of the stator stack by a predetermined dimension, The stator coil is formed by being attached to a hub for electrical wiring, and when the coil / hub assembly is inserted into the housing / stack assembly, a gap with the predetermined dimension is formed on the entire circumference and the entire length of the stator coil. Further, the present invention is characterized in that compressed air is flowed from the outside into the gap.
According to a second aspect of the present invention, in the first aspect of the present invention, a gap communicating with the gap is formed between the outer peripheral surface of the coil / hub assembly and the inner peripheral surface of the housing / stack assembly. Compressed air is supplied to the gap, and the entire circumference and the entire length of the stator coil are circulated in the gap formed between the outer peripheral surface of the coil tip / hub assembly and the inner surface of the housing / stack assembly. The compressed air is discharged.
According to a third aspect of the present invention, in the invention according to the second aspect, a front flange having a plurality of through holes for discharging compressed air is attached to the housing / stack assembly, and an O-ring is attached to the stator coil tip of the coil / hub assembly. A presser collar is attached, and by inserting an O-ring between the rear end of the front flange and the O-ring presser collar, the intrusion of compressed air into the ball bearing attached to the inner periphery of the front flange is prevented. Features.
According to a fourth aspect of the present invention, in the first, second, or third aspect, the gap formed by the predetermined dimension is 0.2 to 0.5 mm.
Specifically, the present invention has the following configuration.
A stator stack formed by laminating a large number of stator laminations formed by punching thin silicon steel plates of 0.2t and 0.35t that are electrically insulated on both sides with a press is fixed in the stator housing by bonding or the like (housing Stack assembly).
On the other hand, the inner and outer circumferences of the coreless type coil made of glass are reinforced with glass fiber and the stator coil, which is impregnated with varnish and hardened firmly, is bonded to the hub (coil / hub assembly). The stator assembly is completed by bonding to the housing.
In the stator assembly, an air gap of about 0.2 to 0.5 mm is provided on the outer circumference of the stator coil and the inner circumference of the stator stack so as to cover the entire circumference and the entire length of the coil. The stator coil is directly cooled by flowing it.

According to the above configuration, by directly air-cooling the stator coil, the temperature rise due to the heat generation amount I ² R of the current flowing through the stator coil can be suppressed extremely efficiently, and the spindle motor can have high output.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a sectional view showing an embodiment of a high-speed spindle motor according to the present invention.
2 is a sectional view and a side view of a housing / stack assembly according to the present invention, FIG. 3 is a sectional view and a side view of a coil / hub assembly according to the present invention, and FIG. 5 is a sectional view of a stator assembly according to the present invention. And a side view.
The high-speed spindle motor according to the present invention comprises a stator assembly, a rotor assembly, a flange portion that supports and fixes a ball bearing portion, and a connector mount portion that takes out coil wiring.
First, the stator assembly will be described.
The stator assembly 30 includes a housing / stack assembly 10, a coil / hub assembly 20, a front flange 7 and an end flange 8.

The housing / stack assembly 10 is formed by stamping silicon steel plates electrically insulated on both sides of 0.2t and 0.35t with a press, and bonding a stator stack 2 formed by laminating a number of them to the housing 3. . The housing 3 has a cylindrical shape, and a stator stack 2 in which a plurality of silicon steel plates are laminated is attached to a substantially central inner peripheral surface of the cylindrical shape.
The coil / hub assembly 20 includes a hub 5 having a gap g3, which is obtained by reinforcing the inner and outer periphery of a coreless type stator coil 4 formed into a cylindrical shape with glass fiber, and then firmly impregnating the coreless stator coil 4 with a varnish. It is composed by adhering to.

  The stator coil 4 has a structure as shown in FIG. 4, and the end of each coil is drawn from the end face of the stator coil 4, and the end of each coil is connected to each land of the annular terminal board 28. The hub 5 has a cylindrical shape having a step 29, and a terminal board 28 is attached to the step 29. The terminal board 28 has lands 4a, 4b, and 4c for wiring, and the terminals of the three lead wires 6 are soldered to the lands 4a, 4b, and 4c, respectively. A part of the outer peripheral surface of the hub 5 is processed to be flat, and this part becomes a gap g3 which is a passage for passing compressed air.

The coil / hub assembly 20 thus produced is inserted into the housing / stack assembly 10, and the stator coil 4 is disposed in the stator stack 2 and fixedly adhered thereto.
The outer diameter of the stator coil 4 is made smaller than the inner diameter of the stator stack 2 by about 0.2 to 0.5 mm. When the stator coil 4 is inserted through the stator stack 2, it extends over the circumferential surface between the stator stack 2 and the stator coil 4. A gap g5, which is a compressed air passage, is formed.

Next, the end flange 8 is attached to the housing 3. As shown in FIG. 6, the end flange 8 has a cylindrical shape having two steps 8a and 8b, and has a long groove-shaped gap g2 through which compressed air passes in a direction along the axis of the outer peripheral surface. A lead guide groove 8c for leading the lead wire 6 to the outside is formed on the outer peripheral surface opposite to the gap g2.
When the end flange 8 is attached, the end flange 8 is adhered and fixed in the housing 3 with the gap g2 of the end flange 8 and the gap g3 of the hub 5 being aligned. The lead wire 6 is accommodated in the lead guide groove 8 c and led behind the end flange 8.

Finally, the stator assembly 30 is formed by inserting the front flange 7 into the housing 3 and fixing it. As shown in FIG. 7, the front flange 7 has a cylindrical shape, and is formed with eight through holes (gap) g6 for passing compressed air along a circumferential line near the outermost periphery of the cylindrical shape. When the front flange 7 is inserted into the housing 3, the O-ring holding collar 23 attached to the front end of the stator coil 4 protruding from the stator stack 2 hits the O-ring 24 attached to the rear end of the front flange 7. The flow path through which the compressed air flows to the bearing 22 is cut off from the circumferential groove 31 communicating with the gap g5 to crush the grease, and the grease of the bearing 22 is prevented from jumping out by the compressed air. The flow path of the compressed air consisting of the gap g6 is formed. The aforementioned O-ring 24 may be a thin ring-shaped ring made of silicon rubber or the like without a groove or with a groove. However, the O-ring 24 is crushed between the end face of the front flange 7 and the O-ring presser collar 23. It may be inserted.
By assembling as described above, a compressed air flow path including the gaps g2, g3, g4, g5, the circumferential groove 31 and the gap g6 is formed.

  In FIG. 1, the collar 18 is inserted into the front flange 7, the ball bearing 22 is further inserted, and the outer race of the ball bearing 22 is fixed by the bearing screw 21, thereby fixing the ball bearing 22 to the front flange 7.

FIG. 8 is a partial sectional view of the rotor assembly according to the present invention.
The rotor assembly 40 includes a cylindrical magnet 11 fixed to a shaft 9 and balance collars 12 and 13 attached to the front and rear of the magnet 11. The outer periphery of the magnet 11 is covered and reinforced by a reinforcing case 14.
The rotor assembly 40 is inserted from the rear surface of the stator assembly 30, the shaft 9 is inserted into the inner periphery of the ball bearing 22, and the inner race is fixed by the bearing collar 19.
Next, the shaft on the side opposite to the output shaft of the rotor assembly 40 is inserted into the inner periphery of the ball bearing 17, the outer periphery of the ball bearing 17 is inserted into the inner periphery of the end flange 8, and the coil spring 15 is pressed against the collar 16.

FIG. 9 is a sectional view and a side view of the connector mounting base according to the present invention.
The connector mounting base 25 has a cylindrical shape having a plurality of steps, and has a joint coupling portion 25a for connecting a compressed air hose connected to a gap g1 which is a passage of compressed air at a corner of the end portion. A connector mounting hole 25b is provided at substantially the center. The lead wire 6 of the motor is connected to the end of the connector 27 of the connector mounting base 25 in which the joint 26 is attached to the joint coupling portion 25a and the connector 27 is attached to the connector mounting hole 25b. The connector mount 25 is fixed to the housing 3 by aligning the gap g1 of the connector mount 25 with the gap g2 of the end flange 8 and screwing four screws into the screw holes 25c.

With the above assembly, the gap g1 is connected to the gap g2, and the compressed air supplied from the joint 26 connected to the compressed air supply source has the entire length of the stator coil 4 via the gaps g1 to g5, the circumferential groove 31 and the gap g6. The heat generated by the stator coil 4 through the surroundings is taken away, and the compressed air that has taken away the heat is exhausted from the gap g6 of the front flange 7 to the outside of the motor.
The compressed air is compressed air having a pressure of 4 kg / cm ² , for example. By passing through the above-described passage, the stator coil is directly cooled over the entire circumference and length of the stator coil, and Joule heat generated by I ² R is generated. Highly efficient high-speed spindle motor can be realized by discharging to the outside extremely efficiently.

  A spindle motor for driving a tool at high speed in a machine tool.

It is sectional drawing which shows embodiment of the high-speed spindle motor by this invention. It is sectional drawing and the side view of the housing stack assembly concerning this invention. It is sectional drawing and a side view of the coil hub assembly concerning this invention. It is a figure for demonstrating the connection structure of a coil. It is sectional drawing and the side view of the stator assembly concerning this invention. It is the front view of the end flange concerning this invention, a left-right side view, and sectional drawing. It is sectional drawing and the left-right side view of the front flange concerning this invention. It is a fragmentary sectional view of the rotor assembly concerning this invention. It is sectional drawing and the side view of the connector mounting base concerning this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 High speed spindle motor 2 Stator stack 3 Housing 4 Stator coil 5 Hub 6 Lead wire 7 Front flange 8 End flange 9 Shaft 10 Housing / stack assembly 11 Magnet 12, 13 Balance collar 14 Reinforcing case 15 Coil spring 16, 18 Color 17, 22 Ball Bearing 19 Bearing collar
20 Coil / hub assembly 21 Bearing screw 23 O-ring retainer collar 24 O-ring 25 Connector mount 26 Joint 27 Connector 28 Terminal board 30 Stator assembly 40 Rotor assembly

Claims (4)

In a spindle motor configured by incorporating a rotor assembly in a stator assembly,
The stator assembly comprises a housing / stack assembly and a coil / hub assembly,
The housing / stack assembly forms a stator stack on the inner periphery of a cylindrical housing,
The coil / hub assembly is formed by attaching one end of a coreless type stator coil having an outer diameter smaller than the inner diameter of the stator stack to a hub for electrical wiring of the stator coil,
When the coil / hub assembly is inserted into the housing / stack assembly, a gap with the predetermined dimension is formed on the entire circumference and the entire length of the stator coil, and compressed air is allowed to flow from the outside into the gap. Features a high-speed spindle motor. Forming a gap communicating with the gap between the outer peripheral surface of the hub of the coil / hub assembly and the inner peripheral surface of the housing of the housing / stack assembly, and supplying compressed air to the gap;
Compressed air flowing through the entire circumference and length of the stator coil is discharged into a gap formed between a coil tip outer peripheral surface of the coil / hub assembly and a housing inner peripheral surface of the housing / stack assembly. The high-speed spindle motor according to claim 1. A front flange having a plurality of through holes for discharging compressed air is attached to the housing / stack assembly,
Attach an O-ring presser collar to the stator coil tip of the coil / hub assembly,
The intrusion of compressed air into a ball bearing attached to the inner periphery of the front flange is prevented by sandwiching an O-ring between a rear end of the front flange and the O-ring holding collar. 2. The high-speed spindle motor described in 2.   4. A high-speed spindle motor according to claim 1, wherein the gap formed by the predetermined dimension is 0.2 to 0.5 mm.

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