JPH0826895B2 - Method for manufacturing hydrodynamic bearing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a polygon mirror spindle of a laser beam printer, a drum spindle of a video tape recorder, a digital audio tape recorder, etc., a magnetic recording of a floppy disk, a hard disk, a hard drum, etc. The present invention relates to a method for manufacturing a dynamic pressure type bearing used for a rotation support portion of a spindle of a device, office equipment, a computer, or the like.

[Conventional technology]

Conventionally, for example, a spindle of a video tape recorder shown in FIG. 4 is known as a spindle in which this type of dynamic pressure type bearing is assembled.

In the figure, reference numeral 10 denotes a housing, 30 denotes a shaft body, and a shaft body is provided in a cylindrical hole 12 provided in the housing 10.
Herringbone-shaped grooves for generating dynamic pressure 31, 32 provided on the outer diameter surface of the shaft body 30 and the housing 1 opposed thereto.
The inner diameter surface (radial bearing surface) 13 and 14 of the cylindrical hole 12 of 0 constitutes a dynamic pressure type radial bearing. Also housing
The thrust bearing member 20 attached to one end of 10 has a surface (thrust bearing surface) 21 facing the shaft body 30 and provided with a spiral dynamic pressure generating groove 22 shown in FIG. The thrust bearing surface 21 and the shaft body 30 face each other (thrust receiving surface).
33 and 33 form a dynamic pressure type thrust bearing.

In the figure, reference numerals 15 and 16 are air vent holes.

The spindle described above has a shaft body that rotates when either the housing 10 or the shaft body 30 is rotated by a drive mechanism (not shown).
Dynamic pressure is generated by the dynamic pressure generating grooves 31 and 32 of 30 to generate a fluid film by air or other lubricant in the radial bearing clearance, and the pressure of the fluid film causes the housing 10 and the shaft body 30 to move.
And one of them is supported in the radial direction while maintaining a non-contact state with the other, and the dynamic pressure is generated by the dynamic pressure generating groove 22 of the thrust bearing member 20, and the fluid generated in the thrust bearing clearance. Housing 10 and shaft 30 due to membrane pressure
One of the two is configured to be supported in the axial direction and rotate while maintaining a non-contact state with the other.

In the spindle having the above structure, the dynamic pressure generating groove 22 of the thrust bearing member 20 constituting the dynamic pressure type thrust bearing is formed by, for example, an etching method, electric discharge machining or the like, and the thrust bearing member 20 is fixed by the bolt 40 to the housing 10 It is designed to be attached to.

[Problems to be solved by the invention]

In order for the thrust bearing of the above spindle to perform a normal function, the thrust bearing surface 21 of the thrust bearing member 20 and the radial bearing surfaces 13 and 14 of the housing 10 are orthogonal to each other, and the thrust bearing surface 21 is a cylinder of the housing 10. It is required to be concentric with the central axis (axial center) of the hole 12. However, in the conventional spindle, the radial bearing surface 13,1 of the housing 10 is different from the thrust bearing surface 21 of the thrust bearing member 20.
In order to make the four orthogonal to each other, it is necessary to machine the squareness between the radial bearing surfaces 13 and 14 of the housing 10 and the annular surface 17 of the housing 10 on which the thrust bearing member 20 is mounted with high precision, and the housing 10 Since the thrust bearing member 20 is coupled with the bolt 40 at the same time, there is a problem that the processing cost becomes high, and between the step surface 18 of the housing 10 where the thrust bearing member 20 is fitted and the outer diameter surface of the thrust bearing member 20. Since there is a gap in the
When 40 is fastened, the thrust bearing member 20 is mounted so as to be displaced in the radial direction with respect to the axial center of the housing 10, and the concentricity of the thrust bearing surface 21 of the thrust bearing member 20 and the cylindrical hole 12 of the housing 10 Since it becomes difficult to hold the bearing with high accuracy, there is a problem that the function of the thrust bearing is unavoidably deteriorated.

The present invention solves the above-mentioned problems by providing a thrust bearing having a thrust bearing surface with high accuracy in both the squareness with respect to the radial bearing surface of the housing and the concentricity with respect to the axial center of the housing, and the number of parts is small, and An object of the present invention is to provide a method for manufacturing a dynamic pressure type bearing that can be manufactured at low cost.

[Means for solving problems]

In the dynamic pressure bearing manufacturing method of the present invention, the thrust bearing member holds the shaft-shaped member in a chucked state, and cuts the outer diameter surface of one end of the shaft-shaped member and the end surface of this end. To make the end face perpendicular to the outer diameter surface, the process of machining a groove for dynamic pressure generation on one end surface that has been cut, and the periphery of the groove for dynamic pressure generation by cutting this end surface It is manufactured by sequentially performing the step of removing the raised portion and the step of subjecting one end of the shaft-shaped member to a cut-off process to cut and separate one end.

Next, the thrust bearing member is press-fitted into one end of the cylindrical hole so that the end surface side of the thrust bearing member on which the dynamic pressure generating groove is formed faces the cylindrical hole provided in the housing.

〔Example〕

FIG. 1 shows a dynamic pressure type bearing manufactured by the method of the present invention and its assembled state in a spindle of a video tape recorder. The same members and parts as those in FIG. 4 are designated by the same reference numerals. The description of the same components other than the essential parts of the present invention will be omitted.

The thrust bearing member 20 is press-fitted into the upper end of the cylindrical hole 12 machined in the housing 10.
The thrust bearing surface 21 of the thrust bearing member 20 has a second
The spiral dynamic pressure generating groove 22 shown in FIG.

Of the inner peripheral surface of the cylindrical hole 12 of the housing 10, the fitting surface 12a into which the thrust bearing member 20 is press fitted is a radial bearing surface 13,
14 and a large diameter portion 12b processed on the inner peripheral surface between the thrust bearing member fitting surface 12a and the upper radial bearing surface 13 and the upper and lower radial bearing surfaces 13, 14 Air vent holes 16a and 16b communicating with the outside air are provided in the large-diameter portion 12c formed on the inner peripheral surface between them.

Next, a method for manufacturing the above dynamic pressure type bearing will be described in the order of steps.

FIG. 3 shows the manufacturing process of the thrust bearing member.

A shaft member 50 such as a copper alloy shown in FIG. 1I is prepared, and the shaft member 50 is held in a chucked state by a chuck device (not shown).

Then, as shown in the same figure [II], after the peripheral groove 51 is cut away from one end surface of the chucked shaft-shaped member 50 at an appropriate length, the outer diameter surface 53 of one end portion 52 is The outer diameter surface 53 is machined into a cylindrical surface having a diameter that can be press-fitted into the thrust bearing member fitting surface 12a of the housing 10 by cutting the end surface 54 and the end surface 54 to the central axis of the shaft-shaped member 50. On the other hand, the outer peripheral portion is chamfered by processing into a vertical plane.

Next, as shown in FIG. 3 [III], the dynamic pressure generating groove 22 is formed in the machined end surface 54 of the shaft-shaped member 50. The dynamic pressure generating groove 22 of this embodiment is formed into a shape in which four pieces having a semi-crescent shape of a linear groove having a narrow groove width are arranged in a spiral shape from the outer peripheral edge of the end face 54 toward the center. Has been done. The lower part of the same drawing [III] shows a method of processing the above-mentioned half-moon shaped groove having a linear shape. A tool in which a ball 61 having a hardness higher than that of the shaft-shaped member 50 is mounted on one shaft end.
60, the ball 61 of the tool 60 is the end surface 54 of the shaft member 50.
When the tool 60 is moved in the vertical direction while rotating the shaft-shaped member 50 in the forward and reverse directions about its central axis, the end surface 54 of the shaft-shaped member 50 is set. Is plastically processed by the ball 61 of the tool 60 to form the groove 22 having a semi-crescent outline shape. It is preferable to use the tool 60 in which the ball 61 is rotatably mounted, because the ball 61 can be processed with less friction by rolling.
A tool 60 in which the ball 61 does not rotate may be used. ball
As the tool 60 that rotates 61, for example, a ballpoint pen that is commercially available as a writing instrument may be used. When groove processing is performed using the ballpoint pen, the ink that leaches from the tool 60 through the ball 61 becomes a lubricant. Since the friction is further reduced, a groove having a good shape can be processed.

Then, as shown in the same figure [IV], the end surface of the bearing member 50.
When the groove 54 is machined, the raised portion 55 protruding around the dynamic pressure generating groove 22 is removed by cutting. For this cutting process,
As shown in the lower part of FIG. [IV], a method such as grinding using a cup grindstone 62, burnishing using a tool 63 with balls 63a, cutting using a cutting tool 64, etc. is appropriately selected and used.

Then, as shown in FIG.
A shaft-shaped member is formed by cutting off 51 with tool 65
Separate one end 52 from 50.

The thrust bearing member 20 of the present invention is obtained by completing the above steps by one chuck.

Note that the cutting of the circumferential groove 51 on the shaft-shaped member 50 does not have to be the first step in the processing steps. Further, the circumferential groove 51 may be omitted.

Further, the groove processing on one end surface 54 of the shaft-shaped member 50 is
Instead of the method of plastically working with the ball 61 using the tool 60 described in the above step, processing with a cutting tool or laser light may be performed, and such cutting or laser processing also produces a linear groove with a narrow groove width. The groove can be processed.
The dynamic pressure generating groove 22 can be processed into any shape other than the above-mentioned semi-crescent outline shape.

In addition to the above, the dynamic pressure generating groove may be processed by various etching methods, electric discharge machining or the like on the same chuck of the same machine.

When the thrust bearing member 20 obtained by the above process is attached to the housing 10, the dynamic pressure of the thrust bearing member 20 is provided in the opening of the cylindrical hole 12 provided in the housing 10 on the thrust bearing member fitting surface 12a side. The end surface (thrust bearing surface 21) side on which the generating groove 22 is processed is directed to press fit into the cylindrical hole 12 and fit the thrust bearing member fitting surface 12a.

In the hydrodynamic bearing manufactured in this way, since the thrust bearing surface 21 is perpendicular to the outer diameter surface of the thrust bearing member 20, the thrust bearing surface 21 is not directly connected to the radial bearing surfaces 13 and 14 of the housing 10. The angle is highly accurate, and the thrust bearing member 20 is not press-fitted radially eccentrically with respect to the shaft center of the housing 10, so that the thrust bearing member 20 has a high concentricity with respect to the shaft center of the housing 10. It becomes accurate.

Further, a thin linear dynamic pressure generating groove 22 is formed on the thrust bearing surface 21 of the thrust bearing member 20 by the method described in the above manufacturing process.
When the above is processed, the groove area on the thrust bearing surface 21 becomes smaller than the area of the portion (land portion) other than the groove. Therefore, the damping due to the squeeze effect of the thrust bearing surface 21 is large, not only can it be used as a thrust bearing having a large dynamic rigidity, but also it can be processed in a simple process, so the processing cost is low. Become.

Further, when the dynamic pressure generating groove 22 having a wide groove width is processed, or when the dynamic pressure generating groove 22 is processed in a double row as shown in FIG. 2 (b), since the groove area is wide, a thrust of low torque is obtained. It becomes a bearing.

〔The invention's effect〕

As described above, the method for manufacturing a dynamic pressure type bearing of the present invention is for cutting the outer diameter surface and the end surface of one end portion while chucking the shaft-shaped member and for generating the dynamic pressure at the one end surface. Groove processing and cutting of the raised portion around the groove,
Since the thrust bearing member is manufactured by performing a parting process on one end of the shaft-shaped member, and the thrust bearing member is press-fitted into the end of the cylindrical hole provided in the housing to be fitted, The squareness of the thrust bearing surface with respect to the radial bearing surface of the housing and the concentricity of the thrust bearing surface with respect to the axis of the housing are highly accurate. Therefore, according to the present invention, it is possible to obtain a method for manufacturing a dynamic pressure bearing including a highly reliable thrust bearing.

Further, according to the present invention, the thrust bearing member can be manufactured only by performing a series of processing steps on the chucked shaft-shaped member, and it is necessary to perform special precision processing for mounting the thrust bearing member on the housing. Since the manufacturing cost is lower than that of the conventional housing, the manufacturing cost can be reduced.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view showing an assembled state of a dynamic pressure type bearing manufactured by the method of the present invention, and FIGS. 2 (a) and 2 (b).
1 is a plan view showing the thrust bearing surface of FIG. 1, FIG. 3 is a manufacturing process drawing of a thrust bearing member, FIG. 4 is a vertical cross-sectional side view showing an assembled state of a conventional dynamic pressure type bearing, and FIG. FIG. 4 is a plan view showing the thrust bearing surface of FIG. 4. In the figure, 10 is a housing, 12 is a cylindrical hole, 20 is a thrust bearing member, 21 is a thrust bearing surface, 22 is a groove for dynamic pressure generation, 50 is a shaft-shaped member, 52 is one end of the shaft-shaped member, 53 and 54 are outer diameter surfaces and end surfaces, respectively, and 55 is a raised portion.

Claims (1)

[Claims] 1. A shaft-shaped member is held in a chucked state,
A step of cutting the outer diameter surface of one end portion of the shaft-shaped member and the end surface of this end portion to make the end surface perpendicular to the outer diameter surface, and forming a dynamic pressure generating groove on the cut end surface. A step of processing, a step of cutting the end face to remove a raised portion around the dynamic pressure generating groove, and a step of separating one end of the shaft-shaped member from the shaft-shaped member by cut-off processing. The thrust bearing member is manufactured sequentially, and the end surface side of the thrust bearing member on which the dynamic pressure generating groove is processed is directed to the cylindrical hole provided in the housing, and the thrust bearing member is inserted into one of the cylindrical holes. A method for manufacturing a bearing for generating dynamic pressure, characterized in that the bearing is press-fitted into the end and fitted.