JPH0717854Y2 - Bearing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a thrust direction bearing device, and is applicable as a thrust receiver of a magnetic head moving mechanism or the like.

(Prior Art) For example, in a magnetic recording / reproducing apparatus in which an information signal is recorded / reproduced on / from a magnetic recording medium such as a floppy disk, the information signal is recorded / reproduced by slidingly contacting a rotationally driven recording medium. It is necessary to move the magnetic head in the radial direction of the recording medium at a predetermined pitch. As a moving mechanism of such a magnetic head, there is one in which a screw shaft rotatably driven by a rotor of a stepping motor intermittently steps a head carriage supporting the magnetic head. In such a head moving mechanism, it is necessary to accurately hold the position of the screw shaft, particularly the position in the thrust direction, and rotatably support the position. Therefore, bearing devices as shown in FIGS. 3 and 4 have been considered. This is disclosed in Japanese Patent Application No. 1-103609 filed by the present applicant.

In FIGS. 3 and 4, a motor frame 66 is fixed on a main frame 64 of the magnetic recording / reproducing apparatus, and bearing supporting walls 31, 32 are bent at both front and rear ends (up and down in FIG. 3) of the motor frame 66. Is formed by. The bearing device 2 is mounted on one of the bearing support walls 31, 32.
0 is provided, and a bearing 62 is fixed to the other support wall 32 via a mounting plate 34. The bearing device 20 constitutes a bearing in the thrust direction, and the bearing 62 constitutes a bearing in the radial direction. The rotary shaft 24, which is a screw shaft, is rotatably supported by these bearing devices 20, 62.

The mounting plate 34 is attached to the bearing support wall 32 of the motor frame 66.
The stepping motor 30 is fixed via. As is well known, the stepping motor 30 includes a stator 35 including a motor case, a stator core, a drive coil, and the like,
It has a Rotagenet 48. The motor case and the stator core each have comb-teeth-shaped pole teeth formed by cutting and raising on the inner peripheral side. The pole teeth of the motor case and the pole teeth of the stator core are alternately arranged along a circle centered on the rotation shaft 24.

One end of the rotary shaft 24 extends into the cylindrical space surrounded by the pole teeth, and a cylindrical rotor magnet 48 is fixed to the one end of the rotary shaft 24 via a rotor boss. On the rotor magnet 48, magnetic poles of N poles and S poles are alternately formed in the circumferential direction.

A bottom plate 45 is fixed to the outer end (lower end in FIG. 1) of the motor case. The bottom plate 45 has a leaf spring portion 46 formed by cutting and raising in the center portion, and also has a pair of arm portions 47, 47 formed by bending the outer peripheral edge portion in the axial direction of the rotary shaft 24. The arm portions 47, 47 have elasticity, and the engaging claw portions 49, 49 are provided at the tip end portions thereof.
Are formed. The bottom plate 45 is fixed to the outer end of the motor case by engaging the engagement claws 49, 49 with a pair of engagement holes formed in the outer periphery of the stator 35 including the motor case. The leaf spring portion 46 of the bottom plate 45 is a bearing 60.
Form part of the. The bearing 60 constitutes a thrust bearing, and is composed of a steel ball 61 dropped into a conical hole at the end of the rotary shaft 24 and the spring portion 46 for preloading the ball 61 in the thrust direction of the rotary shaft 24. Become.

As shown in detail in FIG. 4, the bearing device 20 has a cup-shaped frame 21 having a bottomed cylindrical recess 22 and a sphere 26 dropped into the recess 22 of the frame 21. Become. One end of the rotary shaft 24 is in contact with the spherical body 26 by the biasing force of the leaf spring portion 46 of the bearing 60. The outer periphery of one end of the rotary shaft 24 is a thin shaft portion, and the thin shaft portion has a bore hole 25
Are formed. The outer end edge of the boring hole 25 is chamfered to form a conical surface 27, and the conical surface 27 is in contact with the spherical body 26. A plate 28 is fixed to the bottom of the recess 22 of the frame 21. Thus, the boring hole of the rotary shaft 24
The conical surface 27 of 25 abuts on the sphere 26, and the sphere 26 abuts on the plate 28 at the bottom of the recess 22 of the frame 21 to form a thrust receiver for the rotary shaft 24.

A notch recess 23, which is slightly larger than the recess 22, is formed around the opening of the recess 22 of the frame 21.
The thin shaft portion of the rotary shaft 24 is inserted into the notch recess 23. An appropriate gap is formed between the thin shaft portion and the inner peripheral wall of the cutout recess 23. The sphere 26 has a great circle portion, that is, a portion of a circle that appears at a cut when a spherical surface is cut along a plane passing through the center of the sphere 26 so that the inner peripheral surface of the recess 22 can be brought into contact with the sphere 26. The relationship between the diameter and the depth of the recess 22 is set. An appropriate minute gap is formed between the sphere 26 and the inner peripheral surface of the recess 22 so that the sphere 26 can rotate. When a radial force is applied to the rotary shaft 24, the spherical body 26 comes into contact with the inner peripheral surface of the concave portion 22 and restricts the movement of the rotary shaft 24 in the radial direction. Therefore, the sphere 26 and the recess 22
The radial bearing of the rotary shaft 24 is configured by the contact with the inner peripheral surface of the. The contact portion of the conical surface 27 of the rotary shaft 24 with respect to the sphere 26 is opposite to the hemisphere including the contact portion with the bottom of the recess 22 across the great circle portion of the sphere 26 facing the inner surface of the recess 22. It is on the hemisphere side. The frame 21 can be made by integral molding of resin.

As shown in FIG. 3, the rotating shaft 24 has a bearing device 20 and a bearing 60.
A lead screw is formed between and, and a pin 59 fixed to the protrusion 58 of the head carriage of the magnetic recording / reproducing apparatus is fitted to the lead screw.

When the drive coil of the stepping motor 30 is energized, the stator 35 including a motor case and a stator core is excited, and the rotor magnet facing the stator 35 is excited.
48 moves in the circumferential direction, and the rotary shaft 24 integrated with the magnetnet 48 is rotationally driven. When the rotary shaft 24 rotates, the pin 59 fitted to the lead screw moves in the rotary shaft 24 direction,
Along with this, the head carriage moves in the direction of the rotary shaft 24.

When the rotary shaft 24 is preloaded by the elastic force of the leaf spring portion 46 in the bearing 60, a force in the thrust direction is applied to the rotary shaft 24 by this preload, and when the head carriage is moved by the rotation of the rotary shaft 24 as described above. A thrust force is applied to the rotary shaft 24. The bearing device 20 receives the force in the thrust direction when the sphere 26 contacts the bottom of the recess 22 of the frame 21. Since the spherical body 26 is in point contact with the bottom of the concave portion 22 and can rotate freely, the rotating shaft 24 can be rotatably supported under a small frictional resistance. Then, even if a radial force is applied to the rotary shaft 24 and the rotary shaft 24 is displaced in the radial direction, the displacement of the rotary shaft 24 is restricted by the spherical body 26 contacting the inner peripheral surface of the recess 22, and The thin shaft portion of the rotary shaft 24 is restricted by the inner peripheral surface of the cutout recess 23.

(Problems to be solved by the invention) According to the bearing device as described above, when an impact is applied,
The rotary shaft 24 is disengaged from the sphere 26, and the end face of the rotary shaft 24 is the frame.
May get on the outer edge A of 21. Even if the end surface of the rotary shaft 24 rides on the outer end surface A of the frame 21, the rotary shaft
If 24 returns and the conical surface 27 fits on the outer peripheral surface of the sphere 26, there is no problem. However, according to the conventional bearing device, there is a drawback in that once the rotary shaft 24 is disengaged from the spherical body 26 and the end face of the rotary shaft 24 rides on the outer end face A of the frame 21, the original position cannot be restored. It was

The present invention has been made in order to solve the problems of the prior art, and includes a frame having a bottomed recess and a sphere mounted in the recess, which is formed at one end of a rotary shaft. In the thrust bearing device in which the hollow hole and the spherical body are formed so as to be capable of contacting each other, even if the rotary shaft is disengaged from the spherical body and the end surface of the rotary shaft rides on the outer end surface of the frame,
An object of the present invention is to provide a bearing device capable of returning the rotating shaft to the original position.

(Means for Solving the Problems) The present invention includes a frame having a bottomed recess and a sphere mounted in the recess, and a boring hole formed at one end of a rotary shaft and the sphere. In the bearing device formed so as to be able to contact with each other, an inclined surface that is inclined with respect to the extending direction of the rotating shaft is provided on the opening end side of the recess, and the radius of the open end of the boring hole is L, When the distance from the outer peripheral surface of one end of the rotating shaft to the boundary between the recess and the outer end surface of the frame is 1, L> 1.

(Operation) When the radius of the open end of the boring hole is L and the distance from the outer peripheral surface of the end of the rotary shaft where the bottomed recess is formed to the boundary between the recess and the outer end face of the frame is 1, L Since it is set to> 1, even if the end surface of the rotating shaft is dislocated from the sphere and rides on the outer end surface of the frame due to impact or the like, the end surface of the rotating shaft slides down along the inclined peripheral wall surface. , The end surface of the rotation shaft moves in the center direction while sliding along the upper surface of the sphere, and easily returns to the original position without being caught by the sphere.

(Embodiment) An embodiment of the bearing device according to the present invention will be described below with reference to FIGS. 1 and 2.

In FIGS. 1 and 2, a bearing device indicated by reference numeral 1 has a cup-shaped frame 11 having a bottomed cylindrical recess 12 and a spherical body 6 dropped into the recess 12 of the frame 11. It becomes. One end of the rotary shaft 2 is in contact with the spherical body 6 by the biasing means as seen in the above-mentioned conventional example. The outer periphery of one end of the rotary shaft 2 is a thin shaft portion, and a conical bore hole 5 is formed in this thin shaft portion. The conical surface of the boring hole 5 is in contact with the spherical body 6. Above frame
A plate 18 is fixed to the bottom of the recess 12 of 11. In this way, the conical surface of the boring hole 5 of the rotating shaft 2 abuts on the spherical body 6, and the spherical body 6 causes the plate 18 at the bottom of the recess 12 of the frame 11 to come into contact.
The thrust bearing of the rotary shaft 2 is configured by abutting against the.

Around the opening side of the recess 12 of the frame 11, a cutout recess 13 that is slightly larger than the recess 12 is formed.
The thin shaft portion of the rotary shaft 2 is inserted into the notch recess 13. An appropriate gap is formed between the thin shaft portion and the inner peripheral wall of the cutout recess 13. The diameter of the sphere 6 is such that the great circle portion, that is, the portion of the circle that appears at the cut when the spherical surface is cut along a plane passing through the center of the sphere 6, can contact the inner peripheral surface of the recess 12. And the depth of the recess 12 is set. An appropriate minute gap is formed between the spherical body 6 and the inner peripheral surface of the recess 12 so that the spherical body 6 can rotate. When a radial force is applied to the rotary shaft 2,
The spherical body 6 comes into contact with the inner peripheral surface of the concave portion 12 and regulates the movement of the rotating shaft 2 in the radial direction. Therefore, the abutment between the spherical body 6 and the inner peripheral surface of the recess 12 constitutes a radial receiver of the rotary shaft 2. The contact portion of the conical surface of the boring hole 5 of the rotating shaft 2 with respect to the sphere 6 includes a hemisphere including the contact portion with the bottom of the recess 12 with the great circle portion of the sphere 6 facing the inner surface of the recess 12 interposed therebetween. And on the opposite hemisphere side.

The notch recess 13 is formed on the opening end side of the recess 12 of the frame 11.
Are formed. The notch recess 13 is deeply formed, and the outer end surface A of the frame 11 is located higher than the contact position between the boring hole 5 and the spherical body 6 of the rotary shaft 2. Therefore, the rotary shaft 2 is hard to come off from the frame 11.

The peripheral wall surface a of the notch recess 13 is formed as a conical surface that opens toward the opening end side and is an inclined surface that is inclined with respect to the extending direction of the rotary shaft 2. When the radius of the open end of the boring hole 5 of the rotary shaft 2 is L and the distance from the outer peripheral surface of the thin shaft portion of the rotary shaft 2 to the boundary between the cutout recess 13 and the outer end surface A of the frame 11 is 1. 1 <L. Therefore,
Even if the end surface of the rotating shaft 2 is disengaged from the sphere 6 and rides on the outer end surface A of the frame 11 due to a shock or the like, the end surface c of the rotating shaft 2 slides down along the inclined peripheral wall surface a, so that the sphere It slides along the upper surface of 6 and moves toward the center, and easily returns to its original position without being caught by the spherical body 6. In order to satisfy the relation of 1 <L, the inclination angle of the inclined wall surface a of the cutout recess 13 with respect to the extending direction of the rotary shaft 2 is kept within a relatively small range. If this inclination angle is made too large, 1> L, and when the rotary shaft 2 tries to return to the original position, the end face c of the rotary shaft 2 falls between the spherical body 6 and the notch recess 13 and is easily caught by the spherical body 6. It becomes difficult for the rotary shaft 2 to return.

A through hole 14 is formed in the bottom of the frame 11 in the direction of the central axis. It is possible to confirm whether or not the plate 18 is attached through the through hole 14, and it is possible to measure rattling of the rotary shaft 2 in the thrust direction.

As described above, according to the above embodiment, the frame 11
Since the notched concave portion 13 on the opening end side of the concave portion 12 is formed as a conical surface and the inclined surface a inclined with respect to the extending direction of the rotating shaft 2 is provided, the end surface of the rotating shaft 2 is temporarily disengaged from the spherical body 6 and the frame is removed.
Even when riding on the outer end surface A of 11, the end surface c of the rotary shaft 2
By sliding down along the inclined wall surface a,
It moves in the direction of the center while traversing over the sphere 6, and can easily return to the original position without being caught by the sphere 6. In other words, the rotating shaft 2 can be moved in a wide range in the radial direction without any problem, and the impact resistance is improved accordingly.

INDUSTRIAL APPLICABILITY The bearing device according to the present invention can be used not only as a bearing for a screw shaft in a magnetic head moving device but also as a thrust receiver for a rotary shaft in any device.
Further, the drive source for the rotating shaft is not limited to the stepping motor, but may be any type of motor, or may be something other than the motor.

(Effect of the Invention) According to the present invention, a frame having a bottomed recess,
A spherical body mounted in the concave portion and a rotary shaft having an end portion having a boring hole abutting against the spherical body are provided, and a thrust receiver for the rotary shaft is configured by abutting the spherical body and the bottom of the concave portion formed in the frame. In the bearing device, the inclined surface that is inclined with respect to the extending direction of the rotating shaft is provided on the opening end side of the concave portion of the frame. Therefore, even if the end surface of the rotating shaft deviates from the spherical body and rides on the outer end surface of the frame, There is an effect that the end surface of the rotating shaft moves in the center direction while crossing over the sphere, and can easily return to the original position without being caught by the sphere.

Further, when the radius of the open end of the boring hole is L and the distance from the outer peripheral surface of the one end of the rotating shaft to the boundary between the recess and the outer end surface of the frame is 1, L> 1. Therefore, even if the end surface of the rotating shaft moves off the sphere and rides on the outer end surface of the frame due to a shock, etc., the end surface of the rotating shaft slides down along the inclined peripheral wall surface, causing the end surface of the rotating shaft to become a sphere. It has an effect that it can slide in the direction of the center while sliding along the upper surface, and can easily return to its original position without being caught by the sphere.

[Brief description of drawings]

FIG. 1 is a sectional front view showing an embodiment of a bearing device according to the present invention, and FIG. 2 is a sectional front view of a frame in the same embodiment.
FIG. 3 is a partially sectional front view showing an example of a conventional bearing device incorporated in a magnetic head feeding mechanism, and FIG. 4 is an enlarged sectional front view of a conventional bearing device portion of the same. 1 ... Bearing device, 2 ... Rotating shaft, 6 ... Sphere, 11 ... Frame, 12 ... Recessed part, 13 ... Notched recessed part which forms a part of recessed part, a ... Sloping surface.

Claims (1)

[Scope of utility model registration request] 1. A frame having a bottomed recess, and a sphere mounted in the recess, wherein the boring hole formed at one end of a rotary shaft and the sphere are in contact with each other. In addition, in the bearing device in which the bottom portion of the concave portion constitutes the thrust bearing of the rotary shaft, an inclined surface that is inclined with respect to the extending direction of the rotary shaft is provided on the opening end side of the concave portion. When the radius of the open end of the counterbore is L and the distance from the outer peripheral surface of one end of the rotary shaft to the boundary between the recess and the outer end surface of the frame is 1, L> 1
A bearing device characterized by the following.