JPH0337413A - Bearing device and manufacture thereof - Google Patents

Abstract

PURPOSE:To shorten processing time and improve mass productivity by forming a bearing having a plurality of channels radially curved from the slide surface center and having widths narrowed toward the center and uniform depths formed thereon by plastic working by use of a metal mold having a protruding part having an outer shape to which the channels are transferred and a determined height. CONSTITUTION:The slide surface 1a of a thrust bearing 1 having a spiral dynam ic pressure generating channel 2 formed thereon and the end surface 3a of the shaft 3 are disposed through a fluid film 4 such as oil in such a manner that the both are faced to each other. When the shaft 3 is rotated in the direc tion A, a fluid charged in the channel 2 generates a pressure by pumping effect as the channel 2 has a spiral form and a width reduced toward the rotating direction, and a large fluid pressure is generated in the shaft center part. Hence, a large support load capacity can be obtained. A metal mold 5 for forming the channel has a protruding part 5a having a shape to which the channel is transferred and a determined height, and the protruding part 5a is pressed to the slide surface 1a of the bearing 1 to form the channel 2. Thus, the mass production is facilitated.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a hydrodynamic bearing device, and in particular to a hydrodynamic bearing device with hydrodynamic pressure generating grooves suitable for cylinder bearings of magnetic recording/reproducing devices (hereinafter referred to as VTRs) and the like. Concerning bearing devices and their manufacturing methods.

[Conventional technology]

Regarding bearing devices used as conventional hydrodynamic thrust bearings,
As described on pages 58 to 63 of 2010, 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. 62-4.9352.

[Problem to be solved by the invention]

In conventional bearing devices, the dynamic pressure generating groove of the thrust bearing is formed using a photoetching method, which is difficult to mass produce and requires a long processing time, resulting in high manufacturing costs. was there.

SUMMARY OF THE INVENTION An object of the present invention is to provide a bearing device that solves the problems of the prior art by processing dynamic pressure generating grooves using a method that is easy to mass-produce and takes a short processing time.

[Means to solve the problem]

In order to achieve the above object, the bearing device according to the present invention has the following features:
A rotating member and a stationary member are opposed to each other via a fluid film, and the opposing sliding surfaces have a #1 linear shape that extends radially from the center of the sliding surface to the outer periphery, and has a width that is approximately uniform and gradually narrows toward the center. In a bearing device in which a plurality of grooves are formed with a depth of It is configured to be formed by 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 curved shape that goes radially from the center of the sliding surface to the outer periphery, and has a width that gradually becomes narrower toward the center and a substantially uniform width. In the manufacturing method of a bearing device in which a plurality of grooves with a certain depth are formed, a mold having a convex portion having an outer shape of each groove and a predetermined height is pressed onto one of the sliding surfaces. The grooves are formed by plastic working.

In addition, the height of the convex part of the mold is such that the center part is high and the outer peripheral part is low.The mold is made of materials with different longitudinal elastic modulus. A structure in which the proportion of the heights of the parts can be changed may also be used.

Furthermore, a plastic working method for the sliding surface of a bearing device in which a plurality of grooves are formed in a curved shape extending radially from the center of the circular end face to the outer periphery and having a width that gradually narrows toward the center and a substantially uniform depth. In this method, a mold having a convex portion having an outer shape and a predetermined height, which is a transfer of each groove, is pressed against the end surface to form the groove.

In a magnetic recording and reproducing device that includes a rotating part having 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 magnetic tape is arranged opposite to the upper end surface of a shaft provided at the center of the fixed part. The thrust bearing which is disposed as such, rotates together with the rotating part, and floats and supports the rotating part via a fluid film is configured to be a bearing device according to claim 1.

Further, in a laser beam printer, which includes a rotating part having a polygon mirror and a fixed part supporting the rotating part, the polygon mirror of the rotating part emits laser light to record on a photosensitive drum.
A thrust bearing according to claim 1, which is disposed at the center of a rotating part so as to face the lower end surface of a shaft that rotates together with the rotating part, is fixed to a fixed part, and supports the shaft by floating through a fluid film. The structure is a bearing device.

[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, the lubricant, such as oil, disposed between the width and the thrust bearing is encouraged to pump as the shaft rotates, generating a large pressure and forming 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, the dynamic pressure generating grooves are formed by pressing a mold with a shape in which the periphery of the convex part is low and continuously rises in the direction of the center against the sliding surface of the thrust bearing. The mold becomes uniform in height over the entire area of the convex portion due to elastic deformation. This makes the depth of the groove substantially uniform in both the center and the periphery.

〔Example〕

An embodiment of the present invention will be described with reference to FIGS.

As shown in FIGS. 1 and 2, 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 (groove) 2 is provided radially from the center of a to the outer circumference. Dynamic pressure generating groove 2
In this example, a large number of grooves having the same shape are regularly arranged, and the grooves @b of each groove are continuously narrowed in the direction of rotation A of the shaft facing the sliding surface 1a. Further, as shown in the construction drawing, the cross section of the groove is rectangular, and the groove depth d is substantially uniform over the entire area.

The thickness of the base body (disc) of the thrust bearing 1 in this example is 1.8 mm and the diameter is 15 mm, and this example is particularly effective when applied to such an extremely thin thrust bearing. The maximum width C of each groove 2 is ↓, 8 mm, and the part of the groove 2 that opens into the central recess 2a is @e
is 0.2 to 0.3 mm. Further, the diameter of the recessed portion 2a is 0.5 mm.

On the other hand, the depth d of the groove 2 in this example is 3 μm.

Next, the operation of this embodiment will be explained.

As shown in FIG. 3, the thrust bearing 1 is arranged with a fluid film 4 such as oil in between so that the end surface 3a of the shaft 3 faces the sliding surface 1a of the thrust bearing 1 in which a spiral dynamic pressure generating groove 2 is formed. do. In this embodiment, oil having a viscosity of about 40 Stix is used. By rotating the shaft 3 in the direction A in this state, the fluid filling the dynamic pressure generating groove 2 is formed so that the groove 2 has a spiral shape and the width gradually becomes smaller in the direction of rotation. Therefore, 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 capacity, and the shaft 3
The axial flying height also increases.

The dynamic pressure generating groove as described above can be easily formed by the method shown in FIG. In the same figure,
The mold 5 has a convex portion 5a having a shape that is a transcription of the dynamic pressure generating groove formed in the thrust bearing and a predetermined height. Therefore, the convex portion 5a of this mold 5 is pressed against the sliding surface 1a of the thrust bearing 1, and the dynamic pressure generating groove 2 is formed on this sliding surface ↓a. In addition, as shown in FIG.
The height h of the convex portion 5a is high at the inner circumference and low at the outer circumference.

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

Accordingly, 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 substantially uniform over the entire area, and a dynamic pressure generating groove having a substantially uniform groove depth can be formed in the thrust bearing as shown in FIG.

When using a mold in which the height of the convex part changes continuously as described above, it is possible to easily form dynamic pressure generating grooves with a substantially uniform groove depth due to elastic deformation in the height direction of the mold. can.

In this example, the height of the convex part of the mold is continuously changed so that the groove depth is uniform over the entire area, but by partially changing the height of the convex part, it is possible to It is also possible to form dynamic pressure generating grooves with a groove depth of .

In addition, by selecting various materials with different longitudinal elastic modulus as the material for the mold, it is possible to create dynamic pressure generating grooves with different amounts of elastic deformation of the mold and different groove depth ratios between the outer circumference and the inner circumference. can be 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. I can do it. In addition, for the dynamic pressure generating groove as described in 1. above, a mold having a convex portion having an outer shape and a predetermined height, which is a transfer of the groove shape, is placed on either the sliding surface of the thrust bearing or the sliding surface of the shaft. Since it can be easily formed by pressing, the processing time can be significantly reduced compared to photoetching. Furthermore, if the thrust bearing of this example 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 it is possible to reduce the rotational load torque. can.

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

FIG. 8 shows a magnetic recording/reproducing device 7 according to another embodiment of the present invention.
FIG. 2 is a perspective view of the cylinder 8, in which the outer box is partially transparent and the cylinder 8 is shown. FIG. 9 shows an example of this cylinder 8.

In the embodiment shown in FIG. 9, a grooved thrust bearing is applied to the rotating member. In this figure, a thrust bearing 1 having dynamic pressure generating grooves formed on its sliding surface is fixed to an upper cylinder 10 such that its sliding surface faces a shaft 3. In this state, the upper cylinder 10 is moved by the driving force of the motor 9.
By rotating the thrust bearing 1, the thrust bearing 1 also rotates, and accordingly, the groove surface also rotates, and fluid pressure is generated by the pumping action of the dynamic pressure generating groove, thereby floating and supporting the upper cylinder 10 in the axial direction.

Further, FIG. 10 shows the constituent countries of a laser beam printer according to another embodiment of the present invention, including a photosensitive drum 12, a correction lens 13. A cylindrical lens 14, a collimator lens 15, a semiconductor laser 16, and a laser scanner F are each illustrated.

FIG. 11 shows an example of this laser scanner 17.

In the embodiment shown in FIG. 11, a grooved thrust bearing is applied to the fixed member. In this figure, a motor 9, a radial bearing 18, a polygon mirror 19, and a housing 20 are shown, respectively. A thrust bearing 1 having a dynamic pressure generating groove formed on its sliding surface is fixed to a housing such that its sliding surface faces the shaft 3. In this state, by rotating the polygon mirror 19 with the driving force of the motor 9, the shaft 3 fitted to the polygon mirror 19 also rotates, so that relative slippage between the shaft 3 and the grooved thrust bearing 1 is prevented. The fluid pressure is generated by the pumping action of the dynamic pressure generating groove, and the polygon mirror 19 is floated and supported 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. 12 schematically shows how the grooves are formed in the present invention in relation to the stationary member and the rotating member. FIG. 12 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 the present invention, the relationship of being narrow (wide) in the rotation direction 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 are obtained. Therefore, there is less torque loss on the sliding surface of the thrust bearing, and the amount of wear is also significantly reduced.

In addition, since the dynamic pressure generating groove can be easily formed by a plastic working method, processing time is shortened, manufacturing cost is reduced, and mass productivity is significantly improved.

[Brief explanation of drawings]

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, and FIG. 3 is a diagram showing the pressure distribution on the thrust bearing surface of FIG. 1. FIG. 4 is a sectional view showing the mold of the thrust bearing in FIG. 1, FIG. 5 is a sectional view of the mold, and FIG. 6 is a sectional view showing the surface pressure when pressing the mold.
Fig. 7 is a sectional view showing elastic deformation of the mold, Fig. 8 is a perspective view of another embodiment of the present invention, Fig. 9 is a sectional view of the VTR cylinder unit of Fig. 8, and Fig. 10 is a sectional view of the present invention. FIG. 11 is a cross-sectional view of the polygon mirror unit shown in FIG. 10, and FIG. 12 is a plan view defining the width direction of the groove when the present invention is applied to a thrust bearing. . 1... Thrust bearing (stationary member), 2... Dynamic pressure generating groove, 3... Shaft (rotating member)
, 4...Fluid film, 4...Mold, 30...
・Bearing device.

Claims (1)

[Claims] 1. A rotating member and a stationary member are opposed to 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 facing the center. In a bearing device in which a plurality of grooves are formed with gradually narrowing widths and approximately uniform depths, each groove is formed into a mold having a convex portion having an outer shape and a predetermined height that are transcribed from each groove. A bearing device characterized in that it is formed by pressing onto one of the sliding surfaces and performing plastic working. 2. A rotating member and a stationary member are opposed to each other via a fluid film, and the opposing sliding surfaces have a curved shape that extends radially from the center of the sliding surface to the outer periphery, and has a width that gradually becomes narrower toward the center. In a method for manufacturing a bearing device in which a plurality of grooves having a uniform depth are formed, a mold having a convex portion having an outer shape of each groove and a predetermined height is pressed against one of the sliding surfaces. A method for manufacturing a bearing device, characterized in that each groove is formed by plastic working. 3. The method for manufacturing a bearing device according to claim 2, wherein the height of the convex portion of the mold is set higher at the center and lower at the outer periphery. 4. The method for manufacturing a bearing device according to claim 2 or 3, wherein the mold is made of materials having different moduli of longitudinal elasticity, and the ratio of the heights of the convex parts in the central part and the outer peripheral part is changed. . 5. Plastic processing of the sliding surface of a bearing device to form a plurality of grooves having a curved shape extending radially from the center of the circular end face to the outer periphery and having a width that gradually narrows toward the center and a substantially uniform depth. 1. A method for roughening a sliding surface of a bearing device, characterized in that a mold having a convex portion having an outer shape and a predetermined height on which each groove is transferred is pressed onto the end surface to form the groove. 6. In a magnetic recording and reproducing apparatus that includes a rotating part having 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, a shaft provided at the center of the fixed part is provided. 2. A magnetic recording and reproducing apparatus, wherein the thrust bearing, which is disposed facing the end face, rotates together with the rotating section, and floats and supports the rotating section via a fluid film is the bearing device according to claim 1. 7. A laser beam printer comprising a rotating part having a polygon mirror and a fixed part supporting the rotating part, and recording on a photosensitive drum by emitting laser light from the polygon mirror of the rotating part, wherein the rotating part 2. A thrust bearing according to claim 1, wherein the thrust bearing is provided at the center of the shaft and is disposed opposite to the lower end surface of the shaft that rotates together with the rotating section, and is fixed to the fixed section and supports the shaft floatingly via a fluid film. A laser beam printer characterized by being a bearing device.