JP3023517B2 - Rotating machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotating machine in which protrusions and holes having different hardnesses are fixed by press-fitting.

[0002]

FIG. 4 is a half sectional view of an example of a conventional spindle motor for driving a hard disk. a is an aluminum bracket, and b is a ferromagnetic stainless steel fixed shaft fixed to the bracket a by an interference fit. Reference numeral c denotes a cylindrical aluminum rotor hub, which is rotatably supported on the fixed shaft b via an upper ball bearing d, a lower ball bearing e, and an annular bush f.

[0003] g is a magnetic fluid seal. In this magnetic fluid seal g, the annular conductive pole pieces h and i and the annular permanent magnet j are held by the annular holder k with the permanent magnet j sandwiched between the pole pieces h and i. It is held via conductive adhesives m1 and m2. The annular holder k is fixed inside the rotor hub c via conductive adhesives m1 and m2. Then, conductive magnetic fluids o and p are magnetically held between the pole pieces h and i and the fixed shaft b. With such a configuration, the static electricity generated in the hard disk r passes through the rotor hub c, the conductive adhesives m1 and m2, the annular holder k, the conductive adhesive m, the pole piece h, and the conductive magnetic fluid o, and passes through the fixed shaft. Escaped through b.

The hard disk r is stacked via a spacer t on a protruding portion s which is annularly protruded from the outer periphery of the lower end of the rotor hub c in the figure, and the uppermost hard disk r is attached to the upper end of the rotor hub c by a clamp member. u
By pressing downwards in the figure, it is fixed to the rotor hub c. As described above, if the material of the bracket is aluminum and the material of the fixed shaft fixed to the bracket by the interference fit is stainless steel,
When trying to press-fit the fixed shaft into the fitting hole of the bracket, the hardness of the two greatly differs, so the fixed shaft will bite the fitting hole of the bracket at the time of press-fitting, and the accuracy of the fitting will deteriorate, and the rotor will not fit. This tends to adversely affect the rotational accuracy of the motor.

The present invention has been made in view of the above-mentioned problems in the prior art, and an object of the present invention is to provide a structure in which protrusions and holes having different hardnesses are formed by press-fitting. It is an object of the present invention to provide a rotating machine which can be fitted and fixed efficiently and accurately.

[0006]

In order to achieve the above object, a rotating machine according to the present invention has two members fixed to each other with a protrusion of another member inserted into a hole of one member. A rotating machine in which the hardness of the material forming the hole and the hardness of the material forming the protrusion are different from each other, wherein the material that can be loosely fitted in the hole and forms the protrusion is provided. An annular member having the same hardness as that of the annular member is fixed to the protrusion by an interference fit, and the annular member and the hole are fixed by crimping by expanding the diameter of the annular member by the interference fit.

[0007]

In the state where the annular member is loosely fitted in the hole, the protrusion is press-fitted into the annular member, and the annular member and the protrusion are fixed by interference fit. Thereby, the outer diameter of the annular member is enlarged, and the annular member and the hole are fixed by pressure. Since the protrusion and the annular member have substantially the same hardness, even if there is a trace of press-fitting between the protrusion and the annular member, scars such as galling that deteriorate the fitting accuracy are not generated.

On the other hand, although the hardness of the annular member is different from that of the hole, the annular member which is loosely fitted in the hole is fixed to the hole by press-fitting due to the expansion of the outer diameter. Scratches such as galling do not substantially occur.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. 1 and 2 relate to a spindle motor for driving a hard disk as one embodiment of the present invention. FIG. 1 is a sectional view of a main part, and FIG. 2 is a half sectional view.

Reference numeral 10 denotes an aluminum bracket;
Is a fixed shaft made of ferromagnetic stainless steel. Bracket 1
0 has a flange portion 14, and a concave portion 1 opening upward in the drawing inside the flange portion 14.
6 are constituted. A cylindrical projection 18 projecting upward is provided at the center of the recess 16, and the inside of the cylindrical projection 18 is a through hole 20 (hole) penetrating the bracket 10 vertically. I have.

Reference numeral 22 denotes the same material as the fixed shaft 12,
2 is a cylindrical member (annular member) that can be tightly fitted with the second through-hole 20 and can be loosely fitted into the through hole 20. This cylindrical member 2
2 is fixed to the lower end portion (projection) of the fixed shaft 12 by an interference fit, and the outer diameter of the cylindrical member 22 and the inner circumference of the through-hole portion 20 are increased by the diameter expansion of the cylindrical member 22 due to the interference fit. The surfaces are crimped and both are fixed.

In order to fix the fixed shaft 12 to the through hole 20 of the bracket 10 through the cylindrical member 22 in the above-described state, first, the cylindrical member 22 is loosely fitted in the through hole 20 and FIG.
The state is as shown in (a). Next, the cylindrical member 22
When the fixed shaft 12 is press-fitted into the
The cylindrical member 22 is fixed by the interference fit.
Is enlarged, the cylindrical member 22 and the through hole 20 are fixed by crimping, and the state shown in FIG. 1B is obtained.

Since the fixed shaft 12 and the cylindrical member 22 are made of the same material, they have the same hardness. Therefore, although there is a trace of press-fitting between the fixed shaft 12 and the cylindrical member 22, a scar such as galling which deteriorates the fitting accuracy does not occur. On the other hand, although the hardness of the through hole 20 is considerably lower than that of the cylindrical member 22, the cylindrical member 22 which is loosely fitted in the through hole 20 is fixed to the through hole 20 by crimping due to the expansion of the outer diameter. There is substantially no scratch such as galling between the member 22 and the through hole 20.

FIG. 3 is a sectional view of a main part of a spindle motor as another embodiment. In this embodiment, the diameter of the squeezed portion 26 slightly reduced from the lower end of the portion of the fixed shaft 24 pressed into the cylindrical member 22 is approximately one third.
Is provided. With such a configuration, the fixed shaft 2
4 is intended to facilitate the operation of press-fitting the cylindrical member 4 into the cylindrical member 22.

Hereinafter, the embodiment shown in FIG. 2 will be further described. Reference numeral 28 denotes an annular circuit board provided in the recess 16 of the bracket 10. Numeral 30 denotes a cylindrical aluminum rotor hub, which comprises a fixed shaft 12 via an upper ball bearing 32, a lower ball bearing 34 and an annular bush 36.
Is rotatably supported. 38 is the upper ball bearing 3
A stator core 40 fixed to the outer peripheral portion of the fixed shaft 12 between the second ball bearing 34 and the lower ball bearing 34 is a stator coil wound around the stator core 38.

Reference numeral 42 denotes a rotor yoke fixed to the inner peripheral surface of the rotor hub 30, and reference numeral 44 denotes a cylindrical rotor magnet fixed to the inner peripheral side of the rotor yoke 42 so as to face the stator core 38 in the radial direction.

Reference numeral 46 denotes a magnetic fluid seal. In the magnetic fluid seal 46, the annular conductive pole pieces 48 and 50 and the annular permanent magnet 52 are held by the annular holder 54 with the permanent magnet 52 sandwiched between the pole pieces 48 and 50. It is held through an adhesive. The annular holder 54 is connected to the upper ball bearing 32 in the figure.
Inside the upper end of the rotor hub 30 above the outer ring of
It is fixed via an adhesive. 56 is an adhesive for sealing. Then, conductive magnetic fluids 58 and 60 are magnetically held between the pole pieces 48 and 50 and the fixed shaft 12.

The hard disk 62 is stacked via a spacer 66 on a projecting portion 64 which protrudes annularly at the outer periphery of the lower end of the rotor hub 30 in the figure, and the uppermost hard disk 62 is screwed to the upper end of the rotor hub 30 by screwing. The rotor hub 30 is pressed by pressing downward in the figure by the attached annular metal clamp member 68.
It is fixed to.

The clamp member 68 is extended on the inner peripheral side so that the upper pole piece 4 in the magnetic fluid seal 46 is formed.
8, and covers the magnetic fluid seal 46 in close proximity to the fixed shaft 12. Reference numeral 68a denotes a protrusion which is in pressure contact with the upper surfaces of the upper pole pieces 48 and 50.

In the embodiment shown in FIG. 4, since the static electricity is supposed to be released via the conductive adhesives m1 and m2, the adhesion failure is caused by the expansion or external force of the conductive adhesives m1 and m2. In the case of the embodiment shown in FIG. 2, the protrusion 68a of the clamp member 68 is pressed against the upper surfaces of the upper pole pieces 48 and 50. The static electricity passes through the rotor hub 30, the clamp member 68, the pole bead 48, and the conductive magnetic fluid 58, and passes through the fixed shaft 1
2 is surely escaped to the outside.

An annular permanent magnet 70 for frequency generation is fixed via a yoke 72 inside the lower side of the overhang portion 64. A frequency power generation coil pattern 74 is provided on the circuit board 28 at a position facing the annular permanent magnet body 70 in the axial direction.

[0022]

According to the rotating machine of the present invention, the protrusions and holes having different hardnesses are fixed by press-fitting. The operation is performed on the member, and the annular member is fixed to the hole by press-fitting due to an increase in the outer diameter thereof, so that a large scar such as galling does not occur. Therefore, good fitting accuracy can be realized efficiently.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a spindle motor according to an embodiment.

FIG. 2 is a half sectional view of a spindle motor according to an embodiment.

FIG. 3 is a sectional view of a main part of a spindle motor according to another embodiment.

FIG. 4 is a half sectional view of a conventional spindle motor.

[Description of sign]

 DESCRIPTION OF SYMBOLS 10 Bracket 12 Fixed shaft 20 Through-hole part 22 Cylindrical member 24 Fixed shaft

Continuation of the front page (56) References JP-A-58-89041 (JP, A) JP-A-2-211033 (JP, A) JP-A-58-190260 (JP, A) JP-A-60-159302 (JP, A) , A) JP-A-55-125045 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02K 5/00-5/26 F16B 3/00-4/00 H02K 7/09 H02K 21/22

Claims (1)

(57) [Claims] 1. A material for forming the hole and a material for forming the protrusion, wherein the two members are fixed to each other with the protrusion of the other member inserted into the hole of one member. A rotating member having a hardness different from that of the hole, wherein an annular member that can be loosely fitted in the hole and has a hardness similar to the material of the protrusion is fixed by the protrusion and the interference fit. A rotating machine characterized in that the annular member and the hole are fixed by crimping by expanding the diameter of the annular member by the interference fit.