JPH03282009A - Bearing device and its manufacturing method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a hydrodynamic bearing device, and in particular, a hydrodynamic bearing device with hydrodynamic pressure generating grooves suitable for cylinder bearings of magnetic recording and reproducing devices (hereinafter referred to as VTR), etc. This article relates to a bearing device and its manufacturing method.

[Conventional technology]

The bearing device used as a conventional hydrodynamic thrust bearing is
Journal of Japan Society of Mechanical Engineers Vol. 89, No. 812 (1986) No. 5
As described on pages 8 to 63, spiral dynamic pressure generating grooves were provided on the sliding surface.

On the other hand, the dynamic pressure generating grooves were formed by photo-etching as described in Japanese Patent Publication No. 49352/1983.

[Problem to be solved by the invention]

In conventional bearing devices, the dynamic pressure generating groove of the thrust bearing is formed using a photo-etching method, which is difficult to mass produce and requires a long time to process, resulting in high manufacturing costs. SUMMARY OF THE INVENTION An object of the present invention is to provide a bearing device in which dynamic pressure generating grooves can be easily mass-produced, the machining time is short, and the manufacturing cost is reduced.

[Means to solve the problem]

In order to achieve the above object, the bearing device of the present invention has a rotating member and a stationary member facing each other with a fluid film interposed therebetween, and a curved line extending radially from the center of the sliding surface to the outer periphery on the opposing sliding surface. In shape and.

In a bearing device in which a plurality of grooves are formed, each groove having a width that gradually narrows toward the center and a substantially uniform depth, each groove has a convex portion with a predetermined height and an inverted outer shape of the respective groove. It is configured to be formed by pressing a mold against one of the sliding surfaces and performing plastic working.

The rotating member and the stationary member are opposed to each other via a fluid film, and the opposing sliding surfaces have a width that is curved radially from the center of the helical surface to the outer periphery and gradually narrows toward the center. Bearing devices that have multiple grooves with almost uniform depth are made by pressing a mold with a convex part with an inverted outer shape and a predetermined height against one of the sliding surfaces. Each groove is formed by machining.

In addition, the height of the convex part of the mold is such that the center part is high and the outer periphery is low. It is also possible to have a configuration in which the height ratio of the convex portions is changed.

Further, after the grooves are transferred, a mold having a smooth pressing part is pressed against the groove transfer surface to form a bearing device by plastic working.

In addition, the height of the pressing part of the mold is high at the center and low at the outer periphery, and the mold is made of materials with different longitudinal elastic modulus. It may also be one in which the height ratio can be changed.

In a VTR that includes a rotating part with a magnetic head and a fixed part that supports the rotating part, and records and reproduces data by winding a magnetic tape around the rotating part, the shaft is arranged opposite to the upper end surface of a shaft provided at the center of the fixed part. A thrust bearing that is provided, rotates together with the rotating part, and floats and supports the rotating part via a fluid film has the same structure as the bearing device described in claim 1t.

In addition, in a laser beam printer that includes a rotating part with a polygon mirror and a fixed part that supports the rotating part, the polygon mirror of the rotating part reflects laser light to record on a photosensitive drum. The thrust bearing, which is arranged opposite to the lower end surface of the shaft that rotates together with the rotating part, is fixed to the fixed part, and supports the shaft by floating through a fluid film, has the same structure as the bearing device according to claim 1. shall be.

[Effect]

According to the present invention, the mold is pressed against the sliding surface of the bearing device,
By continuously narrowing the width of the spiral dynamic pressure generating groove provided on the sliding surface of the thrust bearing in the direction of rotation and toward the center of the shaft, the cross-sectional area of the groove decreases in the direction of rotation. Therefore.

A lubricant such as oil disposed between the width and the thrust bearing facilitates the pumping action accompanying the rotation of the shaft, generates a large pressure and forms a fluid film, resulting in a large supported load capacity. Similarly, the axial flying height of the support member in the bearing device increases.

On the other hand, by pressing a mold with a shape in which the periphery of the convex part is low and continuously high towards the center to transfer the dynamic pressure generating grooves onto the sliding surface of the thrust bearing, the mold is elastically deformed. This results in a uniform height over the entire area of the convex portion. As a result, the bottom of the groove becomes flat, but the land portion of the groove is lower at the center and higher at the periphery, resulting in uneven depth of the groove.

Furthermore, by pressing a mold with a smooth pressing part whose periphery is low and continuously rising toward the center against the groove transfer surface, the mold is elastically deformed and has a uniform height over the entire pressing part. It's going to be. As a result, the land portion is compression-molded to a predetermined uniform height, and the depth of the groove is approximately uniform in both the center and the periphery.

〔Example〕

An embodiment of the present invention will be described based on FIGS. 1 to 3.

As shown in FIGS. 1 to 3, the shaft (rotating member) 3
and a thrust bearing (stationary member) 1.
The sliding surface 1a of one of the thrust bearings 1 is
A curved (spiral) dynamic pressure generating groove 2 is provided radially from the center of a to the outer periphery. The dynamic pressure generating groove 2 has a large number of grooves of the same shape arranged regularly, and the width of each groove becomes continuously narrower in the direction of rotation A of the shaft facing the sliding surface 1a. Further, as shown in FIG. 1, the cross section of the groove is rectangular, and the groove depth d is fairly uniform over the entire area.

The thickness of the base body (disc) of the thrust bearing 1 in this embodiment is 1.8+m+-the diameter is 15m, and this embodiment is particularly effective in application to such an extremely thin thrust bearing.

The maximum width C of each dynamic pressure generating groove 2 is 0.5×11, and the width e of the portion of the groove 2 that opens into the central depression 2a is 0.05 to 0.1 mm.

Further, the diameter of the recessed portion 2a is 0.5 mm.

First, the depth d of the groove 2 in this embodiment is 3 μm.

Next, the operation of this embodiment will be explained.

As shown in FIG. 3, the spiral dynamic pressure generating groove 2
The end face 3a of the shaft 3 is placed so that it faces the sliding surface 1a of the thrust bearing 1 formed with a fluid film 4 of oil or the like.6 In this embodiment, oil with a viscosity of about 40 centistics is used. . By rotating the shaft 3 in the input direction in this state, the fluid filled in the dynamic pressure generating groove 2 will be formed so that the groove 2 has a spiral shape and the width gradually becomes smaller in the rotation direction. Because of this, pressure is generated by the pumping action of the groove. Therefore, as shown in FIG. 3, a large fluid pressure is generated near the center of the shaft. As a result, the thrust bearing 1 can obtain a large supporting load, and the axial flying height of the shaft 3 and the like also becomes large.

The dynamic pressure generating groove can be easily formed by the method shown in FIG. In the figure, a mold 5 has a convex portion 5a having a shape that is an inversion of the dynamic pressure generating groove 2 formed in the thrust bearing and a predetermined height. Therefore, the convex portion 5a of the mold 5 is pressed against the sliding surface 1a of the thrust bearing 1, and the dynamic pressure generating groove 2 is transferred to the sliding surface 1a. Note that, as shown in FIG. 5, the height h of the convex portion 5a of the mold 5 is
The inner periphery is high and the outer periphery is low.

When the dynamic pressure generating groove 2 of the thrust bearing is coined in such a state, the surface pressure distribution of the mold is as shown in Fig. 6, because the width of the convex part 5a on the inner circumference is narrow and the cross-sectional area is small. , the inner circumference is higher than the outer circumference.

Along with this, the elastic deformation of the convex portion 5a of the mold in the height direction becomes larger at the inner circumference than at the outer circumference, as shown in FIG. Therefore, the height of the convex portion 5a of the mold becomes more uniform over the entire area, and the bottom of the groove becomes more flat as shown in FIG. However, as shown in the figure, the height f of the land portion 1b of the groove is uneven because the width g of the outer circumferential portion is wider than the inner circumferential portion, so that the outer circumferential portion is higher than the inner circumferential portion.

Next, as shown in FIG. 9, the heights of the land portions can be easily aligned and grooves of uniform depth can be formed.

In the figure, the pressing portion 7a of the mold 7 has a smooth surface. Therefore, the pressing part 7a of the mold 7 is pressed against the insertion surface 1a of the thrust bearing 1, and the height f of the land part 1b is compression-molded to a predetermined uniform height, thereby forming a uniform groove depth. do.

Note that, as shown in the figure, the height i of the pressing portion 7a of the mold 7 is processed such that the inner circumferential portion is higher and the outer circumferential portion is lower.

When the thrust bearing is subjected to compression machining in such a state, the surface pressure distribution of the mold 7 becomes higher at the inner circumference than at the outer circumference, as shown in FIG. Along with this, the pressing part 7a of the mold 7
As shown in Fig. 11, the elastic deformation in the height direction of
The inner circumference is larger than the outer circumference. Therefore, the pressing portion of the mold 7 becomes substantially flat over the entire area, making it possible to form a thrust bearing with substantially uniform groove depth as shown in FIG.

As mentioned above, when using the mold 7 in which the pressing surface changes continuously, the groove depth changes due to elastic deformation in the height direction of the mold.
A uniform thrust bearing can be easily formed.

According to this embodiment, since the width of the dynamic pressure generating groove is made narrower in the direction of rotation of the shaft, the pumping action of the groove is promoted, and a large supporting load capacity and axial flying height can be obtained. . In addition, the dynamic pressure generating groove as described above is created by pressing a mold having a convex part with an outer shape of the groove shape and a predetermined height against either the sliding surface of the thrust bearing or the sliding surface of the shaft. By doing so, it can be easily formed, and the processing time can be significantly shortened compared to photoetching. Furthermore, if the thrust bearing of this embodiment is used in the cylinder part of a VTR or the polygon mirror bearing part of a laser beam printer, a large supporting load capacity and axial flying height can be obtained, so that the rotational load torque can be reduced. can.

In the above embodiments, the grooved thrust bearing is used as a stationary member, but since it has the same effect relative to the corresponding member, it may also be applied to a rotating member.

FIG. 12 is a perspective view of a VTR 8 according to another embodiment of the present invention, in which the cylinder 9 is shown with the outer box partially transparent. The 13th example of this cylinder 9 is
It is a diagram.

In the embodiment shown in FIG. 13, a grooved thrust bearing is applied to the rotating member. In this figure, the thrust bearing 1 with hydrodynamic grooves formed on the sliding surface has its sliding surface on the shaft 3.
It is fixed to the upper cylinder 10 so as to face the upper cylinder 10 . By rotating the upper cylinder 10 with the driving force of the motor 11 in this state, the thrust bearing 1 also rotates, so the groove surface also rotates, and fluid pressure is generated by the pumping action of the dynamic pressure generating groove. The upper cylinder 10 is supported floating in the axial direction.

FIG. 14 is a perspective view of a laser beam printer according to another embodiment of the present invention, in which the correction lens 13. Cylindrical lens 14. Collimator lens 15. Semiconductor laser 16. A photosensitive drum 17 and a laser scanner 18 are shown, respectively. FIG. 15 shows an example of this laser scanner 18.

In the embodiment shown in FIG. 15, a grooved thrust bearing is applied to the fixed member. In this figure, motor 11. Radial bearing 19. Polycon mirror 20° housings 21 are each shown. A thrust bearing 1 having dynamic pressure generating grooves formed on its sliding surface is fixed to a housing such that its sliding surface faces a shaft 3. By rotating the polygon mirror 2o with the driving force of the motor 11 in this state, the shaft 3 fitted to the polygon mirror 20 also rotates, so there is no relative slippage between the shaft 3 and the grooved thrust bearing 1. , and a fluid pressure is generated by the pumping action of the dynamic pressure generating groove to float and support the polygon mirror 2o in the axial direction.

As described above, since the thrust bearing to which the present invention is applied can obtain a large flying height, it is possible to realize a VTR cylinder unit with small rotational load torque and a polygon mirror unit of a laser beam printer.

FIG. 16 schematically shows how the grooves are formed in the present invention in relation to the stationary member and the rotating member. FIG. 16 shows the relationship between the groove width and the direction of rotation in the case of a thrust bearing.

As shown in the figure, rotation and rest are relative. Further, in one aspect of the present invention, the relationship of being narrow (wide) in the direction of rotation is defined by FIG.

〔Effect of the invention〕

According to the present invention, a mold is pressed against the sliding surface of the bearing device to form a plurality of grooves (dynamic pressure generating grooves), so it is possible to realize a bearing device that has a large bearing support load and can provide stable support. .

Further, according to the present invention, it is possible to provide a thrust bearing in which the pumping action of the dynamic pressure generating groove is promoted, and a large supporting load capacity and axial flying height can be obtained. For this reason,
There is less torque loss on the sliding surface of the thrust bearing, and the amount of wear is significantly reduced.

In addition, thrust bearings can be easily formed using plastic working methods, reducing processing time and manufacturing costs.
Mass productivity is significantly improved.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a thrust bearing according to an embodiment of the present invention, Fig. 2 is a front view of the thrust bearing of Fig. 1, Fig. 3 is a pressure distribution diagram of the thrust bearing surface of Fig. 1, and Fig. 4 is a diagram of pressure distribution on the thrust bearing surface of Fig. 1. is a sectional view showing the method of forming the grooves in the thrust bearing shown in Fig. 1, Fig. 5 is a sectional view of the mold, Fig. 6 is a sectional view showing the surface pressure when the mold is suppressed, and Fig. 7
The figure is a cross-sectional view showing the elastic deformation of the mold, Figure 8 is a cross-sectional view of the thrust bearing formed in Figure 4, and Figure 9 shows a method of forming the groove by pressing the mold to make the groove depth uniform. 10 is a sectional view showing surface pressure when pressing the mold, FIG. 11 is a sectional view showing elastic deformation of the mold, and FIG. 12 is a perspective view of another embodiment of the present invention. 13 is a sectional view of the VTR cylinder unit of FIG. 12, FIG. 14 is a perspective view of another embodiment of the present invention, and FIG. 15 is a sectional view of the polygon mirror unit of FIG. 10.
FIG. 16 is an explanatory diagram that defines the width direction of the groove when the present invention is applied to a thrust bearing. 1... Thrust bearing, 2... Dynamic pressure generating groove, 3...
Shaft, 4th figure 1st figure 20th rod figure no.

Claims (1)

[Claims] 1. A rotating member and a stationary member face each other via a fluid film, and the opposing sliding surfaces have a curved shape extending radially from the center of the sliding surface to the outer periphery, and extending toward the center. In a bearing device in which a plurality of grooves are formed with gradually narrowing widths and substantially uniform depths, each of the grooves has a mold having a protrusion having an outer shape that is an inversion of the groove and a predetermined height. It is characterized by being formed by pressing a mold having a smooth pressing part against the transcription surface of the groove after the groove is transferred by pressing on one of the sliding surfaces, and by plastic working to make the groove have a uniform depth. Bearing device. 2. A rotating member and a stationary member face each other via a fluid film, and the opposing sliding surfaces have a width approximately equal to that of a curved line extending radially from the center of the sliding surface to the outer periphery, and gradually narrowing toward the center. In a method for manufacturing a bearing device in which a plurality of grooves with uniform depth are formed, a mold having a convex portion having an inverted outer shape of the groove and a predetermined height is pressed against one of the sliding surfaces. 1. A method for manufacturing a bearing device, characterized in that after the groove is transferred, a mold having a smooth pressing part is pressed against the transfer surface of the groove to form the groove by plastic working to a uniform depth. 3. In claim 2, the height of the convex part of the mold that forms the groove and the height of the pressing part of the mold that forms the depth of the groove are such that the center part is high and the outer periphery is high. A method for manufacturing a bearing device with a low section. 4. The method for manufacturing a bearing device according to claim 2 or 3, wherein the mold is made of materials having different modulus of longitudinal elasticity and the height ratio between the center portion and the outer peripheral portion is changed. 5. Plastic processing of the sliding surface of a bearing device to form a plurality of grooves that are curved radially from the center of the circular end face to the outer periphery and have a width that gradually narrows toward the center and a substantially uniform depth. In the method, a mold having a convex part having an outer shape that is an inversion of the groove and a predetermined height is pressed against the end surface to form a groove, and then a mold having a smooth pressing part is pressed onto the grooved surface. A plastic processing method for the sliding surface of a bearing device that processes the groove depth uniformly. 6. A magnetic recording and reproducing device comprising a rotating part provided with a magnetic head and a fixed part supporting the rotating part, and recording and reproducing by winding a magnetic tape around the rotating part, comprising: a shaft provided at the center of the fixed part; 2. A magnetic recording and reproducing apparatus, wherein the thrust bearing is a bearing device according to claim 1, wherein the thrust bearing is disposed opposite to the upper end surface, rotates together with the rotating section, and floats and supports the rotating section via a fluid film. 7. A laser beam printer comprising a rotating part having a polygonal mirror and a fixed part supporting the rotating part, and recording on a photosensitive drum by emitting a laser beam using the polygonal mirror of the rotating part, Claim 1: A thrust bearing which is provided at the center of a part and is arranged to face a lower end surface of a shaft that rotates together with the rotating part, and which is fixed to the fixed part and supports the shaft by floating through a fluid film. A laser beam printer which is a bearing device described in .