JP2006321038A - Main spindle device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a main spindle device which can excellently prevent the damage caused by a collision force from the radial direction and the axial direction without damaging a bolt, etc. <P>SOLUTION: In the main spindle device 10, a radial clearance Cr between the inside peripheral surface of a fixed shock absorbing ring 25 and the outside peripheral surface of a rotary shock absorbing ring 27 is set to be larger than the deflection σrn of a rotary spindle 11 when a radial cutting force Frn is applied thereto, and to be smaller than the deflection σrc of the rotary spindle 11 when a radial collision force Frc is applied thereto, and an axial clearance Ca between the front end surface of the fixed shock absorbing ring 25 and the rear end surface of the rotary shock absorbing ring 27 is set to be larger than the axial displacement σan of the rotary spindle 11 caused by the deflection of a rolling bearing 13 when an axial cutting force Fan is applied thereto, and to be smaller than the axial displacement σac of the rotary spindle 11 caused by the deflection of the rolling bearing 13 when an axial collision force Fac is applied thereto. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a spindle device, and more particularly, to a spindle device used in a machine tool such as a milling machine or a machining center.

  As a conventional spindle device of this type, for example, the one shown in FIG. 6 is known (see, for example, Patent Document 1).

  In the spindle apparatus 100, a rotary shaft 106 with a tool 107 mounted on the front end is rotatably supported by a bearing housing 105 via a rolling bearing 103, and a tool 107 and a workpiece 112 are relatively moved by a feed shaft (not shown). The workpiece 112 is processed by being moved. The spindle device 100 is inserted around the rotary shaft 106 with a minute gap and is detachably fixed to the front end portion of the bearing housing 105, and the seal member 110 is interposed between the outer ring presser 114. Shear bolts 108 and 109 that are fixed to the bearing housing 105 are provided.

Then, an unintended radial collision force due to a program error or the like acts on the rotating shaft 106, the rotating shaft 106 and the seal member 110 come into contact with each other on the rear end side of the tool 107, and the contact portion is used as a fulcrum. When a large bending moment acts on the rotating shaft 106, the shear bolts 108 and 109 generate a predetermined drag force to deform or shear to absorb the collision energy, thereby causing the spindle device 100 to be protected from damage due to collision with a workpiece or the like. I try to protect it.
JP 11-197979 A

  However, in the spindle device 100 described in Patent Document 1, the shear bolt is damaged every time a collision occurs and repair is required. In addition, the spindle device 100 cannot prevent damage to the collision force from the axial direction even though it can prevent damage to the collision force in the radial direction.

  The present invention has been made to eliminate such inconveniences, and the object of the present invention is to satisfactorily prevent damage caused by a collision force from the radial direction and the axial direction without damaging the bolts or the like. It is to provide a spindle device.

The above object of the present invention is achieved by the following configurations.
(1) a rotating shaft;
A bearing housing disposed around the rotating shaft;
A bearing that includes an inner ring that is externally fitted to the rotary shaft, and an outer ring that is fitted to the bearing housing, and that rotatably supports the rotary shaft with respect to the bearing housing;
A fixed buffer ring fixed to the front end of the bearing housing;
A rotation having an outer peripheral surface fixed to the front end of the rotating shaft and radially facing the inner peripheral surface of the fixed buffer ring, and a rear end surface facing the front end surface of the fixed buffer ring in the axial direction. A buffer ring,
A spindle device comprising:
A radial clearance Cr between the inner peripheral surface of the fixed buffer ring and the outer peripheral surface of the rotary buffer ring is larger than a deflection amount σrn of the rotary shaft when a radial load Frn due to processing is applied, and the bearing Is set to be smaller than a deflection amount σrc of the rotary shaft when the radial load Frc acting on the rotary shaft acts on the rotary shaft,
The axial gap Ca between the front end surface of the fixed buffer ring and the rear end surface of the rotary buffer ring is larger than the axial movement amount σan of the rotary shaft due to the deflection of the bearing when the axial load Fan is applied. A main spindle device characterized in that it is set to be larger and smaller than an axial movement amount σac of the rotating shaft due to deflection of the bearing when an axial load Fac that damages the bearing acts on the rotating shaft.

  According to the present invention, the radial clearance Cr between the inner peripheral surface of the fixed buffer ring and the outer peripheral surface of the rotary buffer ring is larger than the deflection amount σrn of the rotary shaft when the radial load Frn due to processing is applied, and Since the radial load Frc that damages the rolling bearing is set to be smaller than the deflection amount σrc of the rotating shaft when acting on the rotating shaft, the rotating shaft is elastic when the radial collision load Frc acts on the rotating shaft. The outer peripheral surface of the rotating buffer ring comes into contact with the inner peripheral surface of the fixed buffer ring and the collision load Frc does not act on the rolling bearing any more. It is possible to satisfactorily prevent the rolling bearing from being damaged by the collision force.

  In addition, since the rotation buffer ring is fixed to the front end portion of the rotation shaft, the contact portion between the outer surface of the rotation buffer ring and the inner surface of the fixed buffer ring is located at the front end of the rotation shaft, and the rotation shaft is greatly bent. Since the moment does not act, damage to the rotating shaft due to the collision force from the radial direction can be well prevented.

  Furthermore, the axial clearance Ca between the front end face of the fixed shock-absorbing ring and the rear end face of the rotation shock-absorbing ring is larger than the axial movement amount σan of the rotating shaft due to the deflection of the rolling bearing when the axial load Fan is applied. In addition, since the axial load Fac that damages the rolling bearing is set smaller than the axial movement amount σac of the rotating shaft due to the deflection of the rolling bearing when acting from the rotating shaft, the collision load Fac in the axial direction is When acting on the rotating shaft, the rolling bearing is elastically deformed, the rear end surface of the rotation buffer ring comes into contact with the front end surface of the fixed buffer ring, and the collision load Fac no longer acts on the rolling bearing. It is possible to satisfactorily prevent the rolling bearing from being damaged by the collision force.

  Hereinafter, a spindle device according to an embodiment of the present invention will be described in detail with reference to the drawings.

  As shown in FIG. 1, the spindle device 10 of the present embodiment includes a rotating shaft 11, a bearing housing 12 disposed around the rotating shaft 11, an inner ring 14 fitted on the rotating shaft 11, and a bearing housing 12. A plurality of rolling bearings 13, which are provided with an outer ring 15 fitted into the inner ring 14 and a rolling element 16 rotatably disposed between the inner ring 14 and the outer ring 15 and rotatably support the rotary shaft 11 with respect to the bearing housing 12. And comprising.

  The outer ring 15 of the rolling bearing 13 is pressed in the axial direction via an outer ring spacer 19 by an outer ring presser 18 fixed to the front end surface of the bearing housing 12 with a bolt 17 or the like, and the inner ring 14 of the rolling bearing 13 is rotated. The bearing 11 is screwed in the vicinity of the front end portion of the shaft 11 and is pressed in the axial direction via the inner ring spacer 21. As a result, the plurality of rolling bearings 13 are fixed in a state in which a predetermined preload is applied in the bearing housing 12.

  A tapered holder mounting hole 22 that gradually decreases in diameter toward the rear end side is formed on the front end surface of the rotating shaft 11, and a tool holder 24 to which a cutting tool 23 is attached is formed in the holder mounting hole 22. It is installed.

  A fixed buffer ring 25 is fixed to the outer ring presser 18 by a bolt 26 on the front end side of the outer ring presser 18, and a rotation buffer ring 27 is screwed and fixed to the front end portion of the rotary shaft 11.

  As shown in FIG. 1B, a large-diameter hole portion 28 and a small-diameter hole portion 29 are formed on the front end side and the rear end side on the inner peripheral side of the fixed buffer ring 25, respectively. On the side, a large-diameter portion 30 and a small-diameter portion 31 that are opposed to the large-diameter hole portion 28 and the small-diameter hole portion 29 of the fixed buffer ring 25 in the radial direction are formed on the front end side and the rear end side, respectively. Thereby, the front end surface 32 of the small diameter hole portion 29 of the fixed buffer ring 25 faces the rear end surface 33 of the large diameter portion 30 of the rotation buffer ring 27 in the axial direction. The fixed shock-absorbing ring 25 and the rotation shock-absorbing ring 27 have sufficient strength so as not to be damaged by a radial collision load and an axial collision load described later.

  The radial clearance Cr between the inner peripheral surface of the large-diameter hole portion 28 of the fixed buffer ring 25 and the outer peripheral surface of the large-diameter portion 30 of the rotation buffer ring 27 is set so that the following equation (1) is satisfied. In addition, the axial gap Ca between the front end surface 32 of the small-diameter hole portion 29 of the fixed buffer ring 25 and the rear end surface 33 of the large-diameter portion 30 of the rotation buffer ring 27 is set so that the following equation (2) is satisfied. Is done.

σrn <Cr <σrc (1)
here,
σrn: Rotated by the radial load Frn acting on the cutting tool 23 during normal cutting
Amount of deflection of the rolling shaft 11 at the position of the clearance Cr σrc: a magnitude that acts on an arbitrary position ahead of the rotating shaft 11 and damages the rolling bearing 13
Of the rotary shaft 11 at the gap Cr position due to the radial load Frc

σan <Ca <σac (2)
here,
σan: By the axial load Fan acting on the cutting tool 23 during normal cutting
Amount of deflection of the rolling bearing 13 and movement of the rotary shaft 11 in the axial direction σac: Axial load F that acts on the cutting tool 23 and damages the rolling bearing 13
The amount by which the rolling bearing 13 is deflected by ac and the rotary shaft 11 moves in the axial direction

  When the above expression (1) is established, as shown in FIG. 2, the rolling bearing 13 normally receives the radial cutting load Frn received from the cutting tool 23 via the tool holder 24 and the rotating shaft 11, and the bearing housing 12. (See F1 in FIG. 2A). For this reason, the radial cutting force Frn in the radial direction does not contact the inner peripheral surface of the large-diameter hole portion 28 of the fixed buffer ring 25 and the outer peripheral surface of the large-diameter portion 30 of the rotation buffer ring 27. That is, as shown in FIG. 2B, since the clearance Cr> 0 is maintained, smooth rotation of the rotating shaft 11 during cutting is ensured.

  Further, as shown in FIG. 3, when a workpiece or the like collides with the cutting tool 23 or the tool holder 24 from the radial direction due to a program error or the like, the radial collision load Frc is transmitted to the rotary shaft 11, and the rotary shaft 11 bends. When the deflection exceeds a certain level, the outer peripheral surface of the large-diameter portion 30 of the rotation buffer ring 27 comes into contact with the inner peripheral surface of the large-diameter hole portion 28 of the fixed buffer ring 25 and the clearance Cr = 0 (see FIG. 3B). Become. For this reason, the collision load Frc is transmitted to the bearing housing 12 via the rotation buffer ring 27 and the fixed buffer ring 25 (see F2 in FIG. 3A), and the collision load Frc does not act on the rolling bearing 13 any more. . Thereby, it is possible to satisfactorily prevent the rolling bearing 13 from being damaged by the collision force from the radial direction without damaging the bolts or the like.

  Further, since the rotation buffer ring 27 is fixed to the foremost end of the rotating shaft 11, the outer peripheral surface of the large diameter portion 30 of the rotation buffer ring 27 and the inner peripheral surface of the large diameter hole portion 28 of the fixed buffer ring 25. Since the contact portion is positioned at the forefront end of the rotating shaft 11, no bending moment acts on the rotating shaft 11, thereby damaging the rotating shaft 11 due to a collision force in the radial direction without damaging bolts or the like. Can be prevented satisfactorily.

  On the other hand, when the above equation (2) is established, as shown in FIG. 4, even if the cutting load Fan in the axial direction is received from the cutting tool 23, the cutting load Fan is not affected by the tool holder 24, the rotary shaft 11, and the rolling bearing. 13 is transmitted to the bearing housing 12 through 13 (see F3 in FIG. 4A). For this reason, the front end surface 32 of the small-diameter hole 29 of the fixed buffer ring 25 and the rear end surface 33 of the large-diameter portion 30 of the rotation buffer ring 27 do not contact each other. That is, as shown in FIG. 4B, the gap Ca> 0 is maintained, and smooth rotation of the rotating shaft 11 is ensured during the cutting process.

  Further, as shown in FIG. 5, when a workpiece or the like collides with the cutting tool 23 or the tool holder 24 from the axial direction due to a program mistake or the like, the rolling bearing 13 is elastically deformed by the collision load Fac in the axial direction and the rotating shaft 11 is moved. If the rear end surface 33 of the large-diameter portion 30 of the rotation buffer ring 27 comes into contact with the front end surface 32 of the small-diameter hole portion 29 of the fixed shock-absorbing ring 25 and Ca = 0 (FIG. 5 ( Refer to b). Therefore, the collision load Fac is transmitted to the bearing housing 12 via the rotation buffer ring 27 and the fixed buffer ring 25 (see F4 in FIG. 5A), and the collision load Fac acts on the rolling bearing 13 any more. Disappear. Thereby, damage to the rolling bearing 13 due to the collision force from the axial direction can be satisfactorily prevented.

  Therefore, according to the spindle device 10 of the present embodiment, the radial gap Cr between the inner peripheral surface of the large-diameter hole portion 28 of the fixed buffer ring 25 and the outer peripheral surface of the large-diameter portion 30 of the rotation buffer ring 27 is cut. It is larger than the deflection amount σrn of the rotating shaft when the radial load Frn due to processing is applied, and smaller than the deflection amount σrc of the rotating shaft 11 when the radial load Frc that damages the rolling bearing 13 acts on the rotating shaft 11. Therefore, when the radial collision load Frc acts on the rotary shaft 11, the rotary shaft 11 is elastically deformed so that the outer peripheral surface of the large-diameter portion 30 of the rotation buffer ring 27 is a large-diameter hole portion of the fixed buffer ring 25. 28, the collision load Frc does not act on the rolling bearing 13 any more, and thereby rolling due to the collision force from the radial direction without damaging the bolts or the like. Damage to the bearing 13 can be satisfactorily prevented.

  Further, since the rotation buffer ring 25 is fixed to the front end portion of the rotary shaft 11, the contact portion between the outer peripheral surface of the rotation buffer ring 27 and the inner peripheral surface of the fixed buffer ring 25 is located at the front end of the rotary shaft 11. In addition, since a large bending moment does not act on the rotating shaft 11, damage to the rotating shaft 11 due to a collision force from the radial direction can be well prevented.

  Further, the axial clearance Ca between the front end surface 32 of the small-diameter hole 29 of the fixed buffer ring 25 and the rear end surface 33 of the large-diameter portion 30 of the rotation buffer ring 27 rolls when an axial load Fan is applied. The axial direction of the rotating shaft 11 due to the deflection of the rolling bearing 13 when the axial load Fac acting on the rotating shaft 11 is larger than the axial movement amount σan of the rotating shaft 11 due to the deflection of the bearing 13 and is damaged. Since the movement amount σac is set to be smaller, if the collision load Fac in the axial direction acts on the rotary shaft 11, the rolling bearing 13 is elastically deformed and the rear end surface 33 of the rotation buffer ring 27 becomes the front end surface of the fixed buffer ring 25. 32, the collision load no longer acts on the rolling bearing 13, so that the rolling shaft is generated by the collision force from the axial direction. Damage to the receiver 13 can be satisfactorily prevented.

In addition, this invention is not limited to embodiment mentioned above, A change, improvement, etc. are possible suitably.
For example, in the present embodiment, both the inner peripheral side of the fixed buffer ring and the outer peripheral side of the rotary buffer ring are formed with a step, but the present invention has a fixed buffer ring having an inner peripheral surface and a front end surface, and a rotary buffer ring. May be formed so as to form an outer peripheral surface and a rear end surface facing each other, and at least one of them may be formed with a step.

The main shaft apparatus which is one Embodiment of this invention is shown, (a) is the principal part sectional drawing, (b) is the I section enlarged view of (a). The state of the clearance Cr when the radial cutting load Frn is applied to the spindle device of FIG. 1 is shown, (a) is a cross-sectional view of the main part thereof, and (b) is an enlarged view of II part of (a). . The state of the clearance Cr when the radial impact load Frc is applied to the spindle device of FIG. 1 is shown, (a) is a cross-sectional view of the main part thereof, and (b) is an enlarged view of part III of (a). . The state of the clearance gap Ca when the axial direction cutting load Fan acts on the spindle apparatus of FIG. 1 is shown, (a) is the principal part sectional drawing, (b) is the IV section enlarged view of (a). . FIG. 1 shows a state of a gap Ca when an axial collision load Fac is applied to the spindle device of FIG. 1, (a) is a cross-sectional view of an essential part thereof, and (b) is an enlarged view of a V part of (a). . It is principal part sectional drawing for demonstrating an example of the conventional main axis | shaft apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Main shaft apparatus 11 Rotating shaft 12 Bearing housing 13 Rolling bearing 25 Fixed buffer ring 27 Rotation buffer ring

Claims (1)

A rotation axis;
A bearing housing disposed around the rotating shaft;
A bearing that includes an inner ring that is externally fitted to the rotary shaft, and an outer ring that is fitted to the bearing housing, and that rotatably supports the rotary shaft with respect to the bearing housing;
A fixed buffer ring fixed to the front end of the bearing housing;
A rotation having an outer peripheral surface fixed to the front end of the rotating shaft and radially facing the inner peripheral surface of the fixed buffer ring, and a rear end surface facing the front end surface of the fixed buffer ring in the axial direction. A buffer ring,
A spindle device comprising:
A radial clearance Cr between the inner peripheral surface of the fixed buffer ring and the outer peripheral surface of the rotary buffer ring is larger than a deflection amount σrn of the rotary shaft when a radial load Frn due to processing is applied, and the bearing Is set to be smaller than a deflection amount σrc of the rotary shaft when the radial load Frc acting on the rotary shaft acts on the rotary shaft,
The axial gap Ca between the front end surface of the fixed buffer ring and the rear end surface of the rotary buffer ring is larger than the axial movement amount σan of the rotary shaft due to the deflection of the bearing when the axial load Fan is applied. A main spindle device characterized in that it is set to be larger and smaller than an axial movement amount σac of the rotating shaft due to deflection of the bearing when an axial load Fac that damages the bearing acts on the rotating shaft.

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