JP2004250832A - Spindle-cooling structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spindle-cooling structure capable of effectively cooling a contact part of a main shaft 44 of a spindle with inner rings of bearings 42 and 43 in the spindle-cooling structure for cooling the main shaft 44 of the spindle connected to a shaft 29 of a motor 20 by a cooling air blowing out from an air outlet 22c of a motor housing 21 through the interior of the motor housing 21. <P>SOLUTION: A cooling air blown out from the air outlet 22c is made to flow from two air inlet holes 44c into a hollow part 44a of the interior of the main shaft 44 of the spindle and is made to flow through a through-hole 44e of the main shaft 44 of the spindle, a recessed part 45a of an inner ring collar, a vertical groove 44f of the main shaft 44 of the spindle and a space between the front end face of the main shaft 44 of the spindle and a front cover 49 to the outside of a spindle case 41. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a spindle cooling structure that cools a main shaft of a spindle connected to a shaft of a motor by using motor cooling air blown out of the housing through the housing of the motor.
[0002]
[Prior art]
Conventionally, this type of spindle cooling structure is provided with an air inlet hole in the vicinity of the connection portion of the spindle main shaft case with a built-in bearing that rotatably supports the main shaft of the spindle to the motor shaft, and on the end surface from which the shaft of the motor housing protrudes. Motor cooling air blown from the provided air outlet is introduced into the spindle case from the air inlet hole to cool the inside of the spindle case.
[0003]
[Problems to be solved by the invention]
In the conventional spindle cooling structure described above, the cooling air introduced into the spindle case cools the inside of the case by removing the surrounding heat while flowing in the vicinity of the outer ring of the bearing.
However, because the air does not flow between the inner ring of the bearing that directly contacts the spindle spindle and generates heat, and the contact area of the spindle spindle does not flow, the cooling effect is insufficient. easy.
The present invention has been made in view of such a problem, and an object of the present invention is to provide a spindle cooling structure capable of effectively cooling a contact portion between a spindle main shaft and a bearing inner ring.
[0004]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a spindle cooling structure for cooling a spindle main shaft coupled to a motor shaft with motor cooling air blown from an air outlet of the housing through the motor housing, The spindle main shaft is formed in a cylindrical structure, a hollow portion inside the spindle main shaft is opened at an end face connected to the shaft, and a through hole communicating with the inside and outside of the spindle main shaft is formed in the spindle main shaft, The motor cooling air is configured to flow into the spindle main shaft from the opening of the spindle main shaft and to flow out of the spindle main shaft through the through hole.
Preferably, the opening includes a coupling hole into which the shaft is fitted, and an air inlet hole for introducing the motor cooling air into the spindle main shaft, and a groove is formed in the outer periphery of the shaft. And a groove is formed in the inner periphery of the connecting hole along the axial direction of the spindle main shaft, the shaft is fitted into the connecting hole, and the shaft groove and the spindle main shaft The shaft and the spindle main shaft are connected by fitting a common connecting pin into the groove.
[0005]
[Operation and effect of the invention]
According to the present invention, since the spindle main shaft is formed in a cylindrical structure so that the cooling air flows inside the spindle main shaft, the spindle main shaft can be cooled from the inside. For this reason, the contact portion between the spindle main shaft and the bearing inner ring can be effectively cooled, and seizure at the contact portion can be prevented, so that the durable life of the spindle main shaft can be greatly increased.
A groove is formed in the motor shaft outer periphery and the spindle main shaft fitting hole, and the shaft and spindle main shaft are connected by fitting a connecting pin in both grooves, so the spindle main shaft has a cylindrical structure. Nevertheless, the shaft and spindle spindle can be connected with a simple structure, and the assembly workability is good.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described below with reference to the drawings. FIG. 1 shows a spindle cooling structure 10 according to an embodiment of the present invention. The cooling structure 10 includes a brushless motor 20 and a spindle device 40 connected to the brushless motor 20.
[0007]
As shown in FIGS. 1 and 2, the housing 21 of the brushless motor 10 includes a motor case 22 and a motor cover 23, and the motor cover 23 is fitted to the motor case 22 via an O-ring 24 so that the rear of the motor case 22. The end face opening is hermetically covered, and a power supply shield line 25 and a cooling air supply hose 26 are connected to the motor cover 23. A pair of front and rear bearings 27 and 28 are built in the motor case 22, and the motor shaft 29 is rotatably supported by the bearings 27 and 28. The front bearing 28 is fitted into a fitting hole provided inside the front surface of the motor case 22, and the rear bearing 27 is fitted into the fitting hole of the bracket 30. The bracket 30 is attached to the opening of the rear end surface of the motor case 22 and is prevented from coming off by a ring 31 screwed inside the opening. The circuit board 32 is fixed to the opposite bearing side of the bracket 30 with a bolt 33, and the power supply shield line 25 is connected to the circuit board 32 through an end cover 34 screwed to the rear end surface opening of the motor case 22. .
[0008]
A magnet 35 is fixed to an intermediate portion of the motor shaft 29, and a magnetic pole rotor 36 is fixed to a rear end portion of the shaft 29 to constitute a rotor. The motor case 22 is provided with an iron core 38 around which a coil 37 is wound so as to surround the magnet 35 fixed to the shaft 29. The iron core 38 is loaded in a cylindrical case 39, and the cylindrical case 39 is fixed to the motor case 22 with a bracket 30. Further, a sensor for detecting the magnetic position of the magnetic pole rotor 36 fixed to the shaft 29 and detecting the rotational position of the shaft 29 is fixed to the bracket 30 at a portion facing the rotor 36. As shown in FIG. 3, two semicircular grooves having a semicircular cross section are arranged at axially symmetrical positions on the outer peripheral portion of the end portion of the motor shaft 29 that protrudes outward from the motor case 22, along the axial direction. Is formed.
[0009]
A plurality of vertical grooves 22a and a plurality of through holes 22b are formed on the outer periphery of the end of the motor case 22 covered with the motor cover 23, and each groove 22a communicates with a corresponding through hole 22b. A plurality of through holes 39 a and a plurality of vertical grooves 39 b are formed in the outer peripheral portion of the cylindrical case 39 loaded with the iron core 38, and the vertical grooves 39 b communicate with the through holes 22 b of the motor case 22. Further, two upper and lower air outlet holes 22c are formed through the bottom of the motor case 22 and open to the outside of the bottom as shown in FIG. Cooling air supplied from the hose 26 flows into a space defined by the motor cover 23 and the end cover 34, passes through the vertical grooves 22 a and the through holes 22 b of the motor cover 22, and further passes through the vertical holes 39 a of the cylindrical case 39. After flowing into the inner space of the motor case 22 through the groove 39b and cooling the iron core 38 and the bearings 27 and 28, the air blows out from the outlet hole 22c at the bottom of the case 22.
[0010]
As shown in FIGS. 1 and 4, the spindle device 40 includes a spindle case 41, and a spindle main shaft 44 is rotatably supported by a pair of front and rear bearings 42 and 43 built in the case 41. Both bearings 42, 43 are screwed inside the front opening end surface of the spindle case 41, an inner ring collar 45 and an outer ring collar 46 mounted on the spindle main shaft 44, a bearing fixing nut 47 screwed to the rear end portion of the spindle main shaft 44. The ring-shaped hold screw 48 is fixed at a predetermined position inside the spindle case 41.
[0011]
The spindle main shaft 44 is formed in a cylindrical shape having a hollow portion 44 a extending in the axial direction inside, and the hollow portion 44 a is open at both front and rear end surfaces of the spindle main shaft 44. As shown in FIG. 5, the opening on the rear end surface of the spindle main shaft 44 has a connecting hole 44b into which the motor shaft 29 is fitted, a pair of left and right air inlet holes 44c, and a pair of upper and lower semicircular grooves 44d having a semicircular cross section. The air inlet hole 44c and the semicircular groove 44d are arranged on the inner peripheral surface of the connecting hole 44b with the axis of the spindle main shaft as a symmetry point, and communicate with the hollow portions of the holes 44b and 44c. The semicircular groove 44 d is formed in a semicircular cross section having the same diameter as the semicircular groove 29 a of the shaft 29. A front cover 49 is screwed to the front end portion of the spindle main shaft 44 so as to rotate integrally with the spindle main shaft 44, and covers the front opening of the spindle case 41. A gap through which air passes is formed between the front opening end face of the spindle case 41 and the front cover 49. A plurality of through holes 44e are formed in the middle portion of the spindle main shaft 44 to communicate the hollow portion 44a of the spindle main shaft 44 with the outside of the spindle main shaft 44. A plurality of vertical grooves 44f are formed on the outer periphery of the main spindle of the spindle from the front side of the through hole 44e, and each vertical groove 44f passes under the inner ring 43a of the front bearing 43 and communicates with the gap. On the other hand, the inner ring collar 45 is formed with a recess 45a in a ring shape that communicates the through hole 44e of the spindle main shaft 44 and the vertical groove 44d. A collet 51 and a nut 52 for removably fixing the cutting tool 50 are assembled to the front end portion of the spindle main shaft 44 protruding from the front cover 49. The spindle main shaft 44 and the motor shaft 29 are fitted with a connecting pin 53 having a circular cross section in each of the two semicircular grooves 29a of the motor shaft 29, and the motor shaft 29 is inserted into the connecting hole 44b of the spindle main shaft 44. Then, each connecting pin 53 is fitted into the semicircular groove 44d of the spindle main shaft 44, and the spindle case 41 is connected to the outer peripheral portion of the front opening of the motor case 22 so as to rotate integrally.
[0012]
The spindle cooling structure 10 according to the present embodiment is as described above. When the coil 37 is energized from the power supply shield wire 25, the motor shaft 29 rotates at a high speed, and the spindle main shaft 44 connected by the connecting pin 53 is the motor. It rotates integrally with the shaft 29. The cooling air blown from the hose 26 flows into the space defined by the motor cover 23 and the end cover 34 as shown by the arrows in FIG. 1, passes through the vertical groove 22a and the through hole 22b of the motor case 22, and is further cylindrical. After flowing into the cylindrical case 39 through the through hole 39a and the longitudinal groove 39b of the case 39, the iron core 38 and the bearings 27 and 28 are cooled, and then blown out from the outlet hole 22c at the bottom of the case 22. Further, the blown cooling air flows into the hollow portion 44a in the spindle main shaft 44 from the two air inlet holes 44c, and passes through the through hole 44e in the spindle main shaft 44, the recess 45a in the inner ring collar, and the vertical groove in the spindle main shaft 44. 44 f flows out of the spindle case 41 through the gap between the front end surface of the spindle main shaft 44 and the front cover 49.
[0013]
According to the spindle cooling structure 10 according to the present embodiment, the spindle main shaft 44 is formed in a cylindrical shape so that the cooling air flows through the hollow portion 44a inside the spindle main shaft 44. Can be cooled from. For this reason, the contact portion between the spindle main shaft 44 and the inner rings of the bearings 42 and 43 can be effectively cooled, and seizure at the contact portion can be prevented, so that the durability life of the spindle device 40 can be greatly increased. In particular, in this embodiment, the vertical groove 44f on the outer periphery of the spindle main shaft 44 passes under the inner ring 43a of the bearing 43, so that the inner ring 43a can be cooled more effectively.
[0014]
Semicircular grooves 29a and 44d are formed in the outer peripheral portion of the shaft 29 of the motor 20 and the inner peripheral portion of the fitting hole 44b of the spindle main shaft 44, and the connecting pin 53 is fitted in both the semicircular grooves 29a and 44d. Since the shaft 29 and the spindle main shaft 44 are connected, the shaft 29 and the spindle main shaft 44 can be connected with a simple configuration, although the spindle main shaft 44 has a cylindrical structure, and the motor 20 and the spindle device 40 are assembled. Can be performed efficiently.
[0015]
Next, FIG. 6 shows a spindle cooling structure according to another embodiment of the present invention. In the embodiment described above, the through hole 44e and the vertical groove 44d are formed in the spindle main shaft 44, and the recess 45a is formed in the inner ring collar 45 so that the cooling air flows through the hollow portion 44a inside the spindle main shaft 44. In the present embodiment, a through hole 44g is formed immediately before the front bearing 43 of the spindle main shaft 44, and cooling air flowing through the spindle main shaft 44 flows out of the gap through the through hole 44g. is doing. Since the other configuration is the same as that of the tenth embodiment shown in FIG. 1, the same components are denoted by the same reference numerals and the description thereof is omitted.
According to this embodiment, the manufacturing cost can be reduced because the drilling of the spindle 44 and the machining of the longitudinal grooves are omitted.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a spindle cooling structure according to an embodiment of the present invention.
FIG. 2 is a front view showing a motor of the spindle cooling structure.
FIG. 3 is a right side view of the motor.
FIG. 4 is a front view showing a spindle device of a spindle having the same spindle cooling structure.
FIG. 5 is a left side view of the spindle device of the spindle.
FIG. 6 is a cross-sectional view showing a spindle cooling structure according to another embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Spindle cooling structure, 20 ... Motor, 21 ... Motor housing, 22c ... Air outlet hole, 29 ... Motor shaft, 29a ... Semicircular groove, 40 ... Spindle device, 42, 43 ... Bearing, 44 ... Spindle spindle, 44a ... hollow part, 44c ... air inlet hole, 44d ... semicircular groove, 44e, 44g ... through hole, 53 ... connecting pin.

Claims (2)

A spindle cooling structure for cooling a spindle main shaft coupled to a motor shaft with motor cooling air blown from an air outlet of the housing through the motor housing, wherein the spindle main shaft is formed into a cylindrical structure. In addition, a hollow portion inside the spindle main shaft is opened at an end face connected to the shaft, and a through hole communicating with the inside and outside of the spindle main shaft is formed in the spindle main shaft, and the motor cooling air is opened in the spindle main shaft. The spindle cooling structure is configured to flow into the main spindle of the spindle from the inside and out of the main spindle of the spindle through the through hole. The opening includes a coupling hole into which the shaft is fitted, and an air inlet hole for introducing the motor cooling air into the spindle main shaft. Forming a groove in the inner peripheral portion of the connecting hole along the axial direction of the spindle main shaft, fitting the shaft into the connecting hole, and common to the shaft groove and the spindle main shaft groove. The spindle cooling structure according to claim 1, wherein the shaft and the spindle main shaft are coupled by fitting a coupling pin.

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