JP2001008404A - Small-sized motor and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a small-sized motor at a low cost by using a composite parts obtained by uniting pressed members with high precision and firmly. SOLUTION: A motor board 8 and a stator core 13 which have been stamped are united with respect to a bearing housing 1, by a plastic flow uniting method which generates pressure on a fitting abutting surface through fitting the motor board and stator core into the bearing housing, pressing the bearing housing, and causing plastic flow.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a small motor and a method for manufacturing the same.

[0002]

2. Description of the Related Art As a bearing unit for a small motor of high-speed precision rotation used for driving a disk (recording medium) of a CD-ROM device, a DVD-RAM device, an HDD device, and a rotating mirror of a laser beam printer, etc. conventionally,
Many ball bearings have been put to practical use. Ball bearings can provide rotational elements that are satisfactory in performance.

On the other hand, plain bearings using synthetic oil as a lubricant have come to be used. Specifically, for example, in an HDD device, as described in Japanese Patent Application Laid-Open No. 7-279961, a motor having a high-speed and high rotational accuracy mounted with a dynamic pressure type sliding bearing has been proposed.

Further, a CD used in a CD-ROM device
As a disk drive motor, a disk drive motor having a built-in slide bearing that operates from a low speed of 500 rotations per minute to a high speed rotation of 8000 rotations is known. Hereinafter, as a typical example, a conventional disk drive motor applied to a CD-ROM device will be described (see Japanese Patent Application Laid-Open No. 9-303398).

FIGS. 15 to 18 are longitudinal sectional side views illustrating a conventional method of connecting a disk drive motor and its components.

FIG. 15 shows the structure of a motor for a desktop type device, and FIG. 16 shows the structure of a motor for a thin notebook type device. There is little difference between the two in terms of the structure of the stationary bearing and the like, and there is a great difference in the clamp portion of the rotating disk. FIG. 17 shows a spin caulking connection method as a typical example of a conventional component part connection method, and FIG. 18 shows an 8-flute intermittent caulking connection method (hereinafter referred to as a chrysanthemum connection method).

In FIG. 15, a bearing unit installed in a stator portion has a bottomed bearing housing in which one end is opened and a thrust bearing cover 105 having a thrust bearing 104 built therein is fixed by a spin caulking method and the other end is sealed. 101, two sliding bearings 10 having a predetermined sintered density.
2 and 103 (in some cases, a felt metal having a larger pore diameter than the bearing is installed in the middle), and a cover 106 for preventing lubricating oil scattering is further installed on the upper part, and the rotating shaft 110 is inserted through this. The sliding bearing 10
2, 103 so as to be rotatably supported.

The inner surfaces of the slide bearings 102 and 103 have a perfect circular or elliptical arc shape. The same type of lubricating oil is dripped in addition to the previously impregnated lubricating oil to fill the gap with the lubricating oil. An oil film is formed between the rotating shaft 110 and the inserted rotary shaft 110 to lubricate the oil film.

This bearing unit is connected to and fixed to a motor board 107 by a chrysanthemum method, and a stator core (hereinafter, referred to as an S core) 109 around which a coil 108 for generating a magnetic field is wound is mounted on the bearing unit with the board. They are fitted and fixed by bonding or the like.

On the other hand, the rotor section is composed of a multi-pole magnetized magnet 111 arranged so as to face the S core 109, a rotor case (hereinafter referred to as R case) 112, a mediating disk 113, and a turntable 114. The inner circumferences of the disk 113 and the turntable 114 are connected to the rotating shaft 110 by press-fitting.
The intermediate disk 12 and the intermediate disk 113 are also integrally rotated by press-fitting.

A turntable 114 is provided with a clamp magnet 115 and a rubber sheet 116. A back yoke 117 is provided below the clamp magnet 115. As a result, a slip is prevented by mounting a CD on the turntable 114 and clamping it with a predetermined magnetic force by a clamper (not shown), thereby enabling reading and writing of information.

Next, in FIG. 16, the stator section has the same configuration as in FIG. The bearing housing 101 and the thrust bearing cover 105 are coupled by a spin caulking method, and the bearing housing 101 and the motor board 107 are coupled by a chrysanthemum caulking method. Further, the joint between the bearing housing 101 and the S core 109 uses a chrysanthemum caulking method and an adhesive.

On the other hand, in the rotor portion, the R case 112
The connection between the media and the mediating disk 113 is performed by a spin caulking method.

In the rotor section, the turntable is omitted, the R case 112 is also used as a turntable, a clamper 118 is provided for fixing a CD, and a spring 11 is provided.
The CD is locked by sliding the pawl 120 in the radial direction by the spring force using the tab 9 and the claw 120.

Next, a description will be given of the method of connecting the components.

Bearing housing 1 by spin caulking method
As shown in FIG. 17, the bearing housing 101 in which the thrust bearing cover 105 is fitted is placed on the work pedestal 201 and has a flat surface with its tip inclined by about 5 to 15 °, as shown in FIG. It is realized by deforming the bearing housing 101 by pressing it with a load of 500N to 1000N while applying the cylindrical push block 202 to the bearing housing 101 while rotating.

As shown in FIG. 18, the bearing housing 101 and the motor board 107 are joined by the chrysanthemum swaging method.
Is placed on the work holder 203 and has a width of 0.8 to 1.2 mm.
The mold punch 204 in which the push blades 204a of the above are equally distributed at eight positions on the circumference is addressed to the joint of the bearing housing 101,
It is realized by pressing with a load of 3000N to 3500N from above.

In any connection method, it is necessary to pay attention to the lower stopping point of the stroke, provide a stopper, and take measures to avoid trouble on the work due to excessive load.

[0019]

A motor for precision rotation driving for driving an information recording medium is required to have a configuration that is low in cost and excellent in mass productivity in addition to high speed and rotation performance.

For high-speed operation, a groove bearing in which a shallow groove for generating dynamic pressure is provided by adding a special processing step to an oil-impregnated bearing has been proposed, and is partially adopted. Although this groove bearing is excellent in performance such as high-speed performance and shaft runout accuracy, it has a problem of lack of mass productivity, and it is difficult to realize sufficient cost reduction.

As shown in FIGS. 15 and 16, using a sintered material for the bearing, in addition to the oil previously impregnated in the sintered bearing, lubricating oil was dropped into the surplus space, and the inner diameter shape was changed to a non-circular shape. By adopting a dynamic pressure bearing shape, a small motor with high rotational performance approaching that of a groove bearing has been realized, and high performance, mass productivity and low cost have been achieved. But newly,
The need to solve the following issues arises.

(1) Motor board, which is a main component, S
For a press-formed product such as a core and an R case, it is required that a fitting gap between the bearing housing and the bearing housing is about 0.02 to 0.1 mm. The function of correcting the deviation of the gap with the housing cannot be provided. Therefore, there is a limit to the coupling accuracy, which is disadvantageous for higher accuracy and higher rigidity.

(2) The conventional coupling structure of the bearing housing requires a pressing blade dedicated to caulking of a complicated shape thinly pointed in a narrow space, and therefore, the NC of the pressing blade is required.
Processing man-hours are required, which hinders miniaturization and makes it difficult to reduce costs.

(3) In the bearing unit, the sintered material is impregnated with lubricating oil and used as a bearing, and is pressed into a bearing housing made of brass and fixed. Therefore, the structure is complicated, the number of parts is large, and it has been an obstacle to cost reduction and miniaturization.

(4) Joining members by the spin swaging method or the chrysanthemum swaging method is a very advantageous and simple joining method for an object that allows a large gap. The part which bears the force includes a forced working area leading to breakage or breakage, and includes an excessively forced working part exceeding the material strength. There is a demand for a member connecting means for utilizing a plastic property of a material and eliminating a forced working area due to excessive destruction or breakage, and for miniaturization, thinning, cost reduction, and resource reduction.

An object of the present invention is to provide a small-sized motor which can be formed at a low cost by using a composite part in which pressed members are firmly connected with high precision and a method of manufacturing the same.

[0027]

SUMMARY OF THE INVENTION The present invention relates to a rotor unit having a stator unit in which a motor is mounted on a stator core having a coil wound on a bearing unit having a bearing for rotatably supporting a rotating shaft, and a rotor case having a magnet mounted thereon. And a rotor unit integrally coupled to a rotating shaft, the motor unit and the stator core being connected to the bearing unit, and the motor unit and the stator core being fitted to the bearing unit. , Which is realized by a connection including a plastic flow connection portion in which a compression force is generated on a fitting butting surface by pressing and causing a plastic flow.

The present invention also provides a stator unit in which a stator core having a coil wound around a bearing unit rotatably supporting a rotating shaft and a motor substrate, and a rotor case having a magnet mounted thereon is integrally rotated with the rotating shaft. In a small motor having a rotor unit coupled to the bearing unit, the bearing unit integrally forms a bearing unit for indicating a rotation axis and a housing unit for coupling the motor substrate and the stator core with a sintered member, The coupling of the motor substrate and the stator core to the unit is performed by fitting the motor substrate and the stator core to the housing portion and pressing the housing portion to cause plastic flow, thereby forming a plastic flow coupling portion that generates a compressive force on the fitting butting surface. It is characterized by being realized by a combination including the following.

The stator core is formed by laminating steel plates subjected to press punching, and the motor substrate is formed by forming steel plates with press-punched coupling holes.

Further, a pressing groove having an inclined surface is formed on a pressing surface of the housing portion.

Further, the rotor portion is characterized in that a rotor case is coupled to a rotating shaft by a plastic flow coupling method.

The present invention also provides a stator unit in which a stator core having a coil wound around a bearing unit rotatably supporting a rotating shaft and a motor substrate, and a rotor case having a magnet mounted thereon is integrally rotated with the rotating shaft. In the method of manufacturing a small motor having a rotor unit coupled to the bearing unit, the motor substrate and the stator core are coupled to the bearing unit by fitting the motor substrate to the bearing unit and pressing the bearing unit to cause plastic flow. This is realized by a plastic flow coupling method that generates a pressing force on the mating butting surface, and thereafter, the stator rotor is fitted to the bearing unit, and the bearing unit is pressed and plastically flows to compress the mating butting surface. It is realized by a plastic flow coupling method that generates a force.

The plastic flow of the bearing unit is
It is characterized by being generated by pressing an inclined surface of a pressing groove formed in a bearing unit with a mold punch.

The tip end of the cutting edge of the die punch is provided with a plurality of inclined surfaces having different slopes.

[0035]

Embodiments of the present invention will be described below with reference to the drawings.

First, a first embodiment will be described.

FIG. 1 is a vertical sectional side view of a small motor according to a first embodiment of the present invention. The small-sized motor is thin and flat so as to be used for driving a recording medium (disk) of a note type CD-ROM device or DVD-RAM device.

The main components of this small motor include a stator section centered on a bearing unit and a rotor section centered on a rotating shaft.

The bearing unit arranged on the stator section has:
Two sliding bearings 2 and 3 formed of a sintered material having a sintering density of 6 to 7 g / cm ³ are press-fitted and installed in a cylindrical bearing housing 1 made of metal such as brass and having openings at both ends. (Although illustration is omitted, in some cases, a felt metal having a lower sintering density than the two sliding bearings 2 and 3 is provided between the two sliding bearings 2 and 3). And a hermetically sealed thrust bearing cover 5 provided with The thrust bearing cover 5 is connected to the lower end surface of the bearing housing 1 by fitting the thrust bearing cover 5 into a bearing cover fitting concave portion 1a formed on the lower end surface of the bearing housing 1 and pressing the bearing housing 1 to form a plastic. This is achieved by a plastic flow coupling method in which the outer peripheral surface of the thrust bearing cover 5 is pressed by flowing.

An annular lubricating oil scattering prevention cover 6 is installed at the upper end opening of the bearing housing 1 (the lubricating oil scattering may be omitted when the drip lubricating oil is small). The slide bearing 2,
Support 3

The inner surface of each of the sliding bearings 2 and 3 is in the shape of an arc of a perfect circle or an ellipse.
In this configuration, a lubricating oil film is formed between the rotating shaft 7 and the inner space of the rotating shaft 7 that is dropped.

The motor substrate 8 is made of a steel plate that has been stamped and provided with a flexible wiring substrate 11 on which a Hall element 9 for detecting the position of a magnetic pole of the rotor and a coil connection terminal 10 are mounted in a superposed state.

The bearing housing 1 is mounted on the motor substrate 8.
To form a bearing unit with a substrate. The coupling between the bearing housing 1 and the motor substrate 8 is performed by fitting the outer periphery of the lower end of the bearing housing 1 into a bearing housing coupling hole 8a formed in the motor substrate 8 and pressing the bearing housing 1 to cause plastic flow. This is realized by a plastic flow coupling method in which the inner peripheral surface of the hole 8a is pressed.

A stator core (hereinafter referred to as an S core) 13 around which a magnetic field generating coil 12 is wound is fitted into the bearing housing 1 of this bearing unit with a substrate, and a plastic flow coupling for pressing the bearing housing 1 is provided. Combine by method. The coil 12 is connected to the flexible wiring board 11
And is configured to function as a stator portion of the motor by soldering to the coil connection terminal 10.

On the other hand, in the rotor portion, a brass intermediate disk 14 is press-fitted and attached to the rotating shaft 7, and a connecting hole 15 a of a rotor case (hereinafter referred to as an R case) 15 formed by pressing around the intermediate disk 14. Are connected to each other by a plastic flow coupling method in which the mediation disk 15 is pressed by fitting.

The R case 15 holds a multi-pole magnetized magnet 16 arranged opposite to the S core 13 by light press-fitting and bonding. In addition, a rubber sheet 17 is provided on the upper surface of the R case 15 so as to also function as a turntable for mounting a recording disk.

On the mediating disk 14, a clamper 18 is provided.
The disk (recording medium not shown) is locked by the claws 19 and the springs 20 provided on the clamper 18.

FIG. 2 is a process chart showing the outline of the assembly process of this small motor. The joining step by the plastic flow joining method, which is a feature of this embodiment, is indicated by a double frame. In each of these joining processes, it is not necessary to uniformly apply the plastic flow joining method.
The method may be selectively applied according to parts assembling conditions, motor use conditions, purpose of use, cost, and the like, and a conventional joining method such as spin caulking or chrysanthemum caulking may be used for a part thereof.

A small motor is formed by cutting and bending many of its components by pressing.
There are also thin parts. Therefore, in order to combine such components with high precision and high strength to realize a small motor, a plastic flow bonding method must be used so that pressed surfaces and thin-walled surfaces can be bonded with high precision and high strength. It is necessary to apply.

Here, the coupling by the plastic flow coupling method will be described with reference to FIG. Here, a member on the side that generates plastic flow by pressing will be described as a coupling member, and a partner member that is coupled by plastic flow will be described as a member to be coupled.

The plastic flow bonding method can be explained on the basis of the "conditions of deformation of Tresca". FIG. 3 (a)
In the member 301, the deformation condition of the
Deformation starts when the difference between the maximum principal stress σ1 and the minimum principal stress exceeds the deformation resistance (Kf), and the deformation coincides with the direction of the minimum principal stress. Utilizing this deformation, a bonding force is generated.
Generally, σ1 requires a stress four to six times as large as Kf. That is, the area for applying the load of the binder is Smm
Assuming that ² , when a load of P = σ1 × S is applied, plastic deformation proceeds, yield stress σ2 occurs in the circumferential direction and σ3 occurs in the radial direction, and plastic deformation starts in each case.
This indicates that the deformation progresses in the radial direction.

In the three-member configuration shown in FIG. 3B, the coupling members 303 and 304 are provided with coupling grooves 303a and 304a which are opened at the abutting surfaces, so that the coupling grooves 303a which are open in the radial direction are provided. , 304a, the plastic flow of the coupling member 302 progresses and the groove is firmly filled, so that the compressive force of the surface pressure and the shearing force of the filled material increase the bonding force. However, even in the case of a thin plate or a member for which a joint groove cannot be machined due to material hardness,
By utilizing the advantages of plastic flow bonding, it is possible to achieve high-precision and high-strength bonding that exceeds conventional bonding performance.

FIG. 3C shows an example of a two-member configuration implemented in this embodiment. Similarly to the three-member configuration, the outer periphery, the inner periphery, the lower surface, and the upper surface of the joined member 305 are restrained as much as possible, and the joining member 306 and the joined member 305 are
The upper surface of the bonding material 306 is pressed by the mold punch 401 so as to prevent the load from dispersing by preventing the floating, warping, deformation, and the like from occurring. In the case of a member in which a connecting groove cannot be formed, a device is devised so as to utilize the advantage of plastic flow bonding by utilizing a pressed surface, enhancing a cut groove for preventing rotation, and increasing a surface pressure generating surface.

Structural factors affecting the plastic flow characteristics and strength in such a plastic flow joining method include the deformability (tensile strength, elongation, yield point, etc.) of the joined member, the hardness of the joined member, and the hardness between the joined members. There are gaps. The features of the application example in this embodiment are as follows.

(1) One side of the coupling member (the side opposite to the coupled member)
Has no open parts. (2) A gap must be allowed on the butted surface of the pressed member. (3) Since the material to be joined is mainly a thin member, it is difficult to machine the joining groove. Further, the inner peripheral surface (generally having a drooping portion, a sheared surface, and a fractured surface) that receives pressure due to plastic flow is a rough surface in order to press the cut surface of the thin member to be joined. (4) A sintered material having a lower elongation than the molten material is used as the connecting member.

By solving the problem in the plastic flow coupling generated by these features, it becomes possible to apply the plastic flow coupling method to the coupling of the components of the small motor.

(D) and (e) in FIG. 3 show experimental examples in which it was confirmed that the above-mentioned problems were solved and the strength described below was obtained.

In order to suppress the flow of the material that progresses to the side opposite to the material to be joined 308 in the joining member 307 due to the feature point (1), the tip surface of the cutting edge 402 a of the die punch 402 has a gradient. Provide. The angle θ of this gradient is set according to the characteristics of the material. In addition, as shown in FIG. 3E, in association with the feature point (2), first, the gap G of the abutting surface between the joining member 310 and the joining member 310 is uniformly filled by the flow of the joining member 309. In order to perform the pressing, the pressing groove 309 having a single gradient is formed in the punch receiving surface on the outer peripheral edge of the coupling member 309.
By providing a, it is possible to cope with the deformation by changing the deformability such as making it easy to shift the deformation by the mold punch 403 toward the material to be bonded 310.

For the problem caused by the feature point (3),
A measure is taken to make the slope shape of the tip end surfaces of the cutting edges 402a and 403a of the mold punches 402 and 403 curved or multiple slopes. The tip surface gradient shape of the cutting edges 402a and 403a,
The angle, the depth, and the like are set according to the deformability of the connecting member, particularly, the elongation. This also helps to reduce the frictional contact resistance associated with die punching.

Regarding the sintered material of the feature point (4), it is necessary to deform it relatively large despite its low elongation, and there is a concern that cracks may occur. In order to avoid this, a relief groove having a small curvature is provided to block the propagation of stress. This is effective when the gap G between the butting surfaces is large even for a material having a large elongation. By doing so, it is possible to generate a practically sufficient bonding force for the sintered material.

In the plastic flow coupling method in which the inclined surfaces are engaged and pressed, the automatic alignment function for correcting the alignment error is also exhibited. In order to prevent eccentricity with respect to the gap G, it is effective to reduce the center deviation between the joined member, the mold punch, and the joining member (a center positioning accuracy of ± 10 μm or less is desirable).

FIG. 4 to FIG. 7 show a part joining step by the plastic flow joining method carried out in this embodiment. The draft angle of the die punch, the polishing of the surface, the hardness, and the like are known matters and will not be described because they are separately considered. Sintered material has deformability close to that of brass material except for its low elongation and brittleness. In addition, the joining apparatus according to this embodiment includes a die punch, a work receiving table, and a member to be joined. The target member holder is made of high-quality rubber or plastic material with low deformation resistance, and part of the load on the mold punch is applied to the target member side to prevent the target member from lifting, thereby preventing errors. To do it.

(1) Coupling between Bearing Housing and Thrust Bearing Cover FIG. 4 shows an embodiment of a plastic flow coupling method between the bearing housing 1 and the thrust bearing cover 5. This connection is a method of connecting the same brass thrust bearing cover 5 to the brass bearing housing 1.

The bearing housing 1 and the thrust bearing cover 5 are manufactured by subjecting a brass material to NC processing. Therefore, the surface roughness of the outer peripheral surface and the inner peripheral surface to be abutted is good, and the gap between both members is 0 μm ± 5 μm, so that the members can be fitted by light press fitting. The plate thickness of the thrust bearing cover 5 is 1 mm.

The bearing housing 1 in which the thrust bearing cover 5 has been fitted into the bearing cover fitting recess 1a is placed on the work receiving table 501 with the thrust bearing cover 5 side up. A cylindrical mold punch 404 having an annular cutting edge 404a with a tip end surface having a width of 150 μm, a gradient of 5 °, and an inner side (the thrust bearing cover 5 side) receding is used, and a load of 4000N to 4500N is applied to the mold punch 404. The cutting edge 404a is pushed down to a depth of 200 μm around the thrust bearing cover fitting portion of the bearing housing 1 while the thrust bearing cover 5 is held down by the joined member presser 601 so that the plastic flow of the bearing housing 1 is reduced. As a result, the outer periphery of the thrust bearing cover 5 was pressed, and the thrust bearing cover 5 was able to be coupled to the bearing housing 1 with a force that resulted in a removal force of 100 N or more. In addition, the sealing property could be secured.

The deviation between the center of the work and the center of the punch was previously adjusted so as to be ± 10 μm or less.

Such plastic flow bonding eliminates the need for forming a thinly pointed caulking blade as in the conventional caulking connection, and is advantageous for miniaturization and space reduction.

(2) Coupling of Bearing Housing and Motor Board FIG. 5 shows an embodiment of a plastic flow coupling method of the bearing housing 1 and the motor board 8.

As described above, the bearing housing 1 is formed by NC
The motor substrate 8 is a cold-rolled steel plate material (SPCC material) obtained by press-punching the outer periphery and the bearing housing coupling hole 8a. Therefore, the motor board 8
When the bearing housing 8 is fitted into the bearing housing coupling hole 8a, the abutment surface has 30
A gap G of ~ 65 µm occurs. Also, the shape of the inner peripheral surface (butting surface) of the bearing housing coupling hole 8a of the motor substrate 8 continues to a drooping portion, a sheared surface, and a fractured surface due to the conditions at the time of pre-processing, and ends with generation of burrs. Further, on the inner peripheral surface of the bearing housing coupling hole 8a, if necessary, three or six detent cut grooves are arranged at regular intervals so as to improve the rotational torque resistance. It is effective.

A large surface pressure due to the plastic flow component of the bearing housing 1 is generated with respect to a shear plane located at the center of the thickness of the motor substrate 8 forming the bearing housing coupling hole 8a, and the bearing is also applied to the upper surface. The outer diameter of the annular cutting edge 405a of the die punch 405 is set to be large according to the average diameter of the bearing housing coupling hole 8a so that the brass material of the housing 1 flows and covers, and the inner diameter of the tip end surface of the cutting edge 405a. The portion is formed as a curved surface having a curvature of 100 μm or less so as to avoid wear and the like. The pressure stroke of the mold punch 405 can be set sufficiently deep because the elongation of the bearing housing (brass material) 1 for plastic flow is high. The die punch 405 had a blade edge 405a having a width of 250 μm and a front end surface having a slope of 10 ° and a slope of which the outer peripheral side retreated.

Then, the bearing housing 1 is connected to the motor board 8.
The bearing housing 1 is placed on the work receiving table 502 with the fitting portion facing upward. Then, the die punch 405 is lowered, and the motor substrate 8 is pressed by the
By pushing the cutting edge 405a into the outer peripheral edge of the end surface of the bearing housing 1 with a load of 5000 N to a depth of 250 μm, the bearing housing 1 is plastically flowed in the outer peripheral direction to fill the gap G, and further presses the butted surface of the motor substrate 8. As a result, both were able to be connected with a pulling force of 200 N or more and a force that provided a rotation resistance of 1 N-m.

The motor substrate 8 has three rotation preventing cut grooves formed on the wall surface of the bearing housing coupling hole 8a. In addition, an annular pressing groove 1b having an inclined surface whose inner side is receded is formed on the end face of the bearing housing 1 into which the cutting edge 405a is pushed, corresponding to the shape of the tip end face of the cutting edge 406a.

(3) Coupling between Bearing Housing and S Core FIG. 6 shows an embodiment of a plastic flow coupling method between the bearing housing 1 and the S core 13.

The S-core 13 is formed by laminating silicon steel plates having a thickness of 350 μm, which have been stamped in an annular shape. The shape of the inner surface (punch cut surface) of each silicon steel plate is substantially the same as that of the motor substrate 8 described above. Therefore, when the bearing housing 1 and the S core 13 are fitted, a gap of 30 to 65 μm is generated between the fitting butting surfaces.

The shape of the tip end surface of the annular cutting edge 406a of the mold punch 406 is a slope that is greatly inclined at a gradient of 25 ° so that the outer peripheral side retreats. And this cutting edge 4
An annular pressing groove 1c having an inclined surface whose inner side is receded was formed on the end face of the bearing housing 1 into which the mold 06a was pushed, corresponding to the shape of the tip end face of the cutting edge 406a of the die punch 406. The outer diameter of the cutting edge 406a of the die punch 406 is set to be substantially at the center of the gap G between the butting surface of the outer peripheral surface of the bearing housing 1 and the inner peripheral surface of the R core 13. Also, the width w of the blade edge 406a of the mold punch 406
Is set to 300 μm, and the indentation depth is set to 350 μm.

Then, the bearing housing 1 is connected to the laminated S core 1
3 and placed on the work receiving base 503, the mold punch 406 is lowered, and
By pressing the cutting edge 406a into the end face of the bearing housing 1 with a load of 5000N while holding down the core 13, the bearing housing 1 is plastically flowed in the outer peripheral direction, and
Were pressed against the mating butted surface of the two, and the two could be joined together by a force that would provide a removal force of 100 N or more and a rotational torque of 1 N-m.

(4) Connection of R Case and Transfer Disk FIG. 7 shows an embodiment of a method of plastic flow connection between the R case 15 and the transfer disk 14.

This connection is made of an intermediate case 14 made of brass and an R case 15 formed by pressing a thin plate SPCC material.
A gap of 30 [mu] m to 60 [mu] m is generated between the joint butting surfaces. When excessive pressure is applied to the R case 15 due to the plastic flow of the mediating disk 14, after joining,
Due to concerns about warpage in the thin R case 15,
The balance of the load applied to the mold punch 407 is important. Further, since the connecting portion of the R case 16 on the side to be connected is a thin-walled member, the cross-sectional area against pressure is small.

Similar to the method of connecting the bearing housing 1 and the motor board 8 shown in FIG. 5, a pressure is generated from the upper side to the R case 15 side simultaneously with the plastic flow deformation so that the thin R case 15 is sandwiched. Mold punch 407
The outer diameter of the annular cutting edge 407a of the
It is set large according to the average diameter of 5a. The tip surface of the annular cutting edge 407a of the mold punch 407 has a width of 250 μm.
m, an inclined surface having a gradient of 10 ° such that the outside recedes. Also, the intermediate disk 1 into which the mold punch 407 is pushed
On the four surfaces, an annular pressing groove 14a having an inclined surface whose inner side is receded, corresponding to the shape of the tip end surface of the cutting edge 407a.
Was formed.

Then, the outer periphery of the mediating disk 14 is fitted into the coupling hole 15 a of the R case 15, placed on the work receiving table 504, the mold punch 407 is lowered, and the R case 15 is held by the member holding member 604. Hold down the cutting edge 4
07a into a depth of 250 μm with a load of 5000N, causing the fitting outer periphery of the mediating disk 14 to plastically flow outward, compressing the inner peripheral surface of the coupling hole 15a of the R case 15, and removing force of 100N. And 0.5 N-m of rotation resistance.

The annular cutting edge 40 of the die punch 407
The inner diameter portion 7a was formed to have a curved surface shape of 100 μm or less to avoid abrasion and the like.

Next, a second embodiment will be described.

As shown in FIG. 8, the compact motor according to this embodiment is obtained by integrating the bearing housing and the slide bearing according to the first embodiment into a sintered bearing housing 21 using a sintered material for the slide bearing. It is formed by sintering. The sintered density of the sintered bearing housing 21 was set to 6.2 to 6.9 g / mm ³ . In order to prevent the lubricating oil from leaking to the surroundings, it is desirable to perform a sintering method or a post-sintering process for increasing the sintering density of the outer peripheral portion. Other components are the same as those of the first embodiment. The advantage of adopting a sintered material for the housing portion is that the use of the molding process facilitates the improvement of productivity, cost reduction and size reduction by integrating the bearing.

The disadvantage is that the housing is made of powder, so that it has a smaller elongation than that of the molten material and is brittle.

As for the deformability, since it has minute voids whose sintering density can be reduced, the initial deformation resistance acts small, but as the deformation progresses, it shows characteristics substantially similar to those of a brass material.

In the sintered bearing housing 21 which has been sintered, the inner bearing portion and the outer housing portion are impregnated with the same lubricating oil. This prevents the lubricating oil component of the bearing portion from moving to the outer peripheral housing portion due to the adsorbing force of the lubricating oil if the housing portion side is not impregnated with the lubricating oil, thereby preventing the lubricating oil in the bearing portion from becoming insufficient. That's why. No adverse effect is seen on the plastic flow action of the housing part.

In this embodiment, it is necessary to set the sintered bearing housing 21 to a shape that is easily deformed in order to deform the brittle sintered bearing housing 21 and generate a plastic flow to obtain a bonding force. is there. Further, it is desirable to provide a stress blocking groove region for preventing the concentration of stress due to large deformation and the generation and breakage of cracks due to this, so as to cover a defect with small elongation.

(5) Coupling of Sintered Bearing Housing and Thrust Bearing Cover FIG. 9 shows an embodiment of a plastic flow coupling method of the sintered bearing housing 21 and the thrust bearing cover 5.

The thrust bearing cover 5 made of brass is fitted into the bearing cover fitting recess 21 a of the sintered bearing housing 21. The gap between the fitting butting surfaces is 0 ± 5 μm, and light press-fitting is possible.

The mold punch 408 has an annular cutting edge 408a that takes into account the reduction in deformation resistance and the reduction in elongation due to the sintering density (6.2 to 6.9 g / mm ³ ) specific to the sintered material. The width w is 200 μm, and the tip surface is 10 ° such that the inside recedes.
Slope.

Then, the sintered bearing housing 21 in which the thrust bearing cover 5 is fitted into the bearing cover fitting concave portion 21a is placed with the thrust bearing cover 5 side facing upward.
Place on. A 4000 N load is applied to the mold punch 408 to lower it, and while the thrust bearing cover 5 is held down by the member holding member 605, the cutting edge 408 a is extended to a depth of 200 μm around the thrust bearing cover fitting portion in the sintered bearing housing 21. The thrust bearing cover 5 is pushed by the plastic flow of the sintered bearing housing 21 by being pushed.
The thrust bearing cover 5 was able to be connected to the sintered bearing housing 21 with a force such that a pulling force of 100 N or more was pressed against the outer periphery of the sintered bearing housing 21.

(6) Coupling of Sintered Bearing Housing and Motor Board FIG. 10 shows an embodiment of a plastic flow coupling method of the sintered bearing housing 21 and the motor board 8.

The motor substrate 8 is made of a cold-rolled material (SPCC).
Is press-punched, a gap of 30 to 65 μm is generated between the mating butted surfaces of the sintered bearing housing 21 and the motor board 8 depending on the component tolerance range.

The mold punch 409 has an annular cutting edge 409a.
The width w is 300 μm, the tip surface is an inclined surface with an inclination of 10 °, and the outer side is set back. The curved surface was designed to avoid wear and the like. Further, an annular pressing groove 21b having an inclined surface whose inner side is retreated is formed in the outer peripheral edge of the end surface of the sintered bearing housing 21 in accordance with the shape of the tip surface of the cutting edge 409a. A radius of curvature of 300 to 500 μm, which is located inside the pressing surface on the bottom surface in the groove 21b
The stress relaxation region was formed by providing an annular stress relaxation groove 21c.

Then, the sintered bearing housing 21 is fitted into the bearing housing coupling hole 8a of the motor substrate 8, and the sintered bearing housing 21 is placed on the work receiving base 506 with this fitted portion facing upward. Then, the die punch 409 is lowered, and the cutting edge 409a is pressed into the outer peripheral edge of the end face of the bearing housing 1 to a depth of 250 μm with a load of 5000 N while the motor substrate 8 is pressed by the connected member presser 606, thereby sintering. The bearing housing 21 is caused to flow plastically in the outer peripheral direction to press the butted surface of the motor substrate 8,
Both were able to be combined with a pulling force of 200 N or more and a force that resulted in a rotation resistance of 1 N-m.

A sufficient surface pressure due to the plastic flow component of the sintered bearing housing 21 at the center of the thickness of the motor substrate 8 could be generated. On the inner surface of the bearing housing coupling hole 8a of the motor board 8, three detent cut grooves are formed as in the above embodiment. Further, it can be estimated that the roughness of the inner surface of the bearing housing coupling hole 8a also contributes to maintaining the coupling force due to the surface pressure.

The stress relaxing groove 21 c is formed in the sintered bearing housing 21 having a low elongation rate by the cutting edge 40 of the die punch 409.
9a, the gap was filled, and the propagation of stress could be alleviated so that cracks did not occur in the sintered bearing housing 21 even in plastic flow processing in which the bearing housing coupling hole 8a of the motor substrate 8 was pressed. .

(7) Coupling of Sintered Bearing Housing and S Core FIG. 11 shows an embodiment of a plastic flow coupling method of the sintered bearing housing 21 and the S core 13.

The S core 13 is formed by laminating silicon steel plates having a thickness of 350 μm and subjected to press stamping in an annular shape. When the S core 13 and the sintered bearing housing 21 are fitted to each other, 35 to 6
A gap of 0 μm occurs. The plastic flow coupling is performed by first filling the gap and then plastically flowing the sintered bearing housing 21 so as to generate a surface pressure. The plastic flow of the sintered bearing housing 21 is generated aiming at the upper part of the laminated S core 13.

The annular cutting edge 410a of the mold punch 410
The width W is set to 300 μm, and the shape of the tip surface is designed to increase the indentation depth and reduce the frictional resistance.
An inclined surface whose outer side receded at a gradient of 25 ° was used.

Then, the die punch 410 is inserted into the end face of the sintered bearing housing 21 into which the cutting edge 410a is pushed.
An annular pressing groove 21d having an inclined surface such that the inside recedes is formed in accordance with the shape of the tip surface of the cutting edge 410a of the cutting edge 410a, and further positioned inside the pressing surface on the bottom surface in the pressing groove 21d. An annular stress relaxation groove 21e having a radius of curvature of 0.3 to 0.5 mm was provided to form a stress relaxation region.

Then, the sintered bearing housing 21 is
The cutting tool 410 is fitted on the core 13 and placed on the work receiving table 507, the mold punch 410 is lowered, and while the S core 13 is pressed by the member holding member 607, the cutting edge 410 a is set to 4000.
By pushing the sintered bearing housing 21 into the end face of the sintered bearing housing 21 to a depth of 300 μm with a load of up to 5000 N, the sintered bearing housing 21 is caused to plastically flow in the outer peripheral direction, and the mating abutment surface with the S core 13 is pressed, and Both were able to be connected by the above-mentioned pulling-out force and a force that resulted in a rotational torque resistance of 0.5 N-m.

The stress relaxing groove 21 e is formed in the sintered bearing housing 21 having a low elongation rate by the cutting edge 41 of the die punch 410.
0a to fill the gap and press the S-core 13 further.
Thus, the propagation of stress was able to be reduced so that cracks did not occur in No. 1.

Next, a third embodiment will be described.

In this embodiment, as shown in FIG.
This is a modification of the plastic flow bonding method. In the above-described first and second embodiments, the tip end surface of the cutting edge of the die punch is formed by a simple one.
The plane was inclined with two gradients. As shown in (a),
The inclination of the tip end surface of the cutting edge 411a is such that, with respect to the stress of σ1 that generates the plastic flow in the coupling member 311, the gap G between the coupled member 312 and the joint member 312 is efficiently filled by the plastic flow due to the stress of σ1 ″. , .Sigma.1 ', the plastic flow is generated, and the surface pressure is efficiently generated to act to secure the bonding force.

In addition, there is a qualitative concern about the loss of the effective load due to the frictional resistance accompanying the pushing of the cutting edge of the die punch.
Therefore, it is desired to more efficiently reduce the frictional resistance, efficiently fill the gap, increase the amount of plastic flow, and increase the surface pressure. By increasing the surface pressure, the "penetration between metals" with respect to the rough surface increases, and the bonding force is strengthened.

In such a plastic flow coupling, the minimum tip stress is reduced, the loss due to frictional resistance is reduced, and the total load is reduced by forming the tip of the cutting edge into a combination of a plurality of slopes and a plurality of curved surfaces. By reducing the load and reliably generating plastic flow in the joint member below the buckling load of the work,
The connecting force can be secured by the pressing force and the shearing force of the connecting member.

Therefore, as shown in FIG. 12 (b), the central part in the width direction of the tip surface of the cutting edge 412a of the die punch has a large gradient (25 °), and the inner peripheral part has a small gradient (10 °). °), and the outer peripheral portion also has a smaller gradient (5 °). With such a blade tip end surface shape, the gap G can be filled, and further, the coupling member 311 can be plastically flowed so that the surface pressure acting so as to sandwich the coupled material 312 increases. Further, by making a contrivance such as adding irregularities to the inclined surface, it is possible to contribute to the enhancement of the surface pressure in the radial direction. In the connecting member 311 made of a brittle material, by providing the stress relaxing groove 311b having an arc-shaped cross section on the bottom surface of the pressing groove 311a, the stress can be relaxed by the plastic flow of the connecting member 311 and the generation of cracks can be avoided. .

As shown in (c), the inclination range of the slope of the tip end surface of the cutting edge 412a is preferably within ± 45 ° at the center of the blade width and within ± 30 ° at other than the center.

Next, a fourth embodiment will be described.

This embodiment has a configuration in which the intermediate disk in the above-described second embodiment is omitted and the R case is directly connected to the rotating shaft by a plastic flow connection method. Other configurations are the same as those of the second embodiment.

FIG. 13 is a vertical sectional side view of a small motor according to this embodiment. The central portion of the R case 22 extends to a position reaching the outer periphery of the rotating shaft 7 and forms a rotating shaft fitting hole 22a into which the rotating shaft 7 is fitted. The rotary shaft fitting hole 22a is a press punched surface or a burring processed surface.

FIG. 14 shows an embodiment of a method of plastic flow coupling between the rotating shaft 7 and the R case 22.

The R case 22 is formed by pressing an SPCC material having a plate thickness of 1 mm, and the rotating shaft 7 has a diameter of 2 mm.
US420J2 material, rotation shaft coupling hole 22a and rotation shaft 7
The gap G of the fitting surface was set to 10 μm or less.

The die punch 413 has an annular cutting edge 413a.
Was formed at a width of 200 μm and the gradient of the tip surface was formed at 0 to 3 °.

The rotation shaft coupling hole 22 of the R case 22
a, the rotating shaft 7 is fitted and placed on the work receiving base 508,
The mold punch 413 is lowered, and the R case 22 is
By pushing the cutting edge 413a around the rotation shaft coupling hole 22a of the R case 22 to a depth of about 200 μm with a load of about 000N, plastic flow that presses the rotation shaft 7 into the rotation shaft coupling hole of the R case 22 And the R case 22
And the rotating shaft 7 could be connected so as to have a removal force of 50 N or more and a rotation resistance of 0.5 N-m. Also, R
The runout of the case 22 was 30 μm or less. The anti-rotation torque has a small groove (not shown) at the joint of the rotation shaft 7.
Can be strengthened.

Such a plastic flow coupling method of the rotating shaft and the R case can be applied to the rotor section in the first embodiment.

The small motor constructed according to each of the embodiments described above is suitable for driving a recording medium (disk) of a CD-ROM device, a DVD-RAM device, or an HDD device. The value of use as various kinds of drive motors in such devices is also great.

[0119]

According to the present invention, the motor board and the stator core are connected to the bearing unit by pressing the bearing board against the fitting abutting surface by fitting the motor board and the stator core into the bearing housing and pressing the bearing housing to cause plastic flow. Since the present invention is realized by a plastic flow coupling method that generates a force, a small motor can be manufactured at low cost by using a composite component in which pressed members are firmly coupled with high precision.

[Brief description of the drawings]

FIG. 1 is a vertical sectional side view of a small motor according to a first embodiment of the present invention.

FIG. 2 is a process diagram showing an assembly process of the small motor of the present invention.

FIG. 3 is an explanatory diagram of a plastic flow bonding method.

FIG. 4 is a longitudinal sectional side view showing a plastic flow coupling method between the bearing housing and the thrust bearing cover in the small motor according to the first embodiment of the present invention.

FIG. 5 is a vertical sectional side view showing a plastic flow coupling method between the bearing housing and the motor board in the small-sized motor according to the first embodiment of the present invention.

FIG. 6 is a longitudinal sectional side view showing a plastic flow coupling method between the bearing housing and the stator core in the small motor according to the first embodiment of the present invention.

FIG. 7 is a vertical sectional side view showing a plastic flow coupling method between the rotor case and the intermediate disk in the small motor according to the first embodiment of the present invention.

FIG. 8 is a vertical sectional side view of a small motor according to a second embodiment of the present invention.

FIG. 9 is a vertical sectional side view showing a plastic flow coupling method between a sintered bearing housing and a thrust bearing cover in the small motor according to the second embodiment of the present invention.

FIG. 10 is a vertical sectional side view showing a plastic flow coupling method between a sintered bearing housing and a motor substrate in a small motor according to a second embodiment of the present invention.

FIG. 11 is a vertical sectional side view showing a plastic flow coupling method between a sintered bearing housing and a stator core in the small motor according to the second embodiment of the present invention.

FIG. 12 is an explanatory diagram of a plastic flow coupling method according to a third embodiment of the present invention.

FIG. 13 is a vertical sectional side view of a small motor showing a fourth embodiment of the present invention.

FIG. 14 is a longitudinal sectional side view showing a plastic flow coupling method of a rotary shaft and a rotor case in a small motor according to a fourth embodiment of the present invention.

FIG. 15 is a vertical sectional side view of a conventional disk drive motor for a desktop type device.

FIG. 16 is a vertical sectional side view of a conventional disk drive motor for a notebook type device.

FIG. 17 is a longitudinal sectional side view showing a spin caulking method.

FIG. 18 is a longitudinal side view showing a chrysanthemum swaging method.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Bearing housing, 2, 3 ... Slide bearing, 5 ... Thrust bearing cover, 7 ... Rotating shaft, 8 ... Motor board, 13 ... Stator core, 14 ... Intermediate disk, 15 ... Rotor case.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Katsutoshi Arai 502, Kandachi-cho, Tsuchiura-shi, Ibaraki F-term in Machinery Research Laboratory, Hitachi Ltd. 5H605 AA07 AA08 BB05 BB14 BB19 CC03 CC04 CC05 CC10 EB02 EB06 FF01 GG04 GG12 GG20 5H607 BB01 BB14 BB25 DD01 DD02 DD03 DD08 EE10 GG02 GG09

Claims (12)

[Claims] A stator unit having a stator core having a coil wound around a bearing unit having a bearing rotatably supporting a rotating shaft and a motor substrate, and a rotor case having a magnet mounted thereon are integrally rotated with the rotating shaft. A motor unit and a stator core connected to the bearing unit, wherein the motor substrate and the stator core are fitted to the bearing unit, and the bearing unit is pressed and plastically flows. A small motor characterized in that it is realized by a connection including a plastic flow connection portion in which a compression force is generated on a mating butting surface of the motor. 2. The stator core according to claim 1, wherein
A small motor characterized by being formed by laminating steel plates subjected to press punching. 3. The small motor according to claim 1, wherein the motor substrate is formed of a steel plate having a connecting hole press-punched. 4. The compact motor according to claim 1, wherein a pressing groove having an inclined surface is formed on a pressing surface of the bearing unit. 5. A stator unit having a stator core having a coil wound around a bearing unit rotatably supporting a rotating shaft and a motor substrate, and a rotor case having a magnet mounted thereon being integrally rotated with the rotating shaft. The bearing unit, the bearing unit supporting the rotating shaft and the housing unit connecting the motor substrate and the stator core are integrally formed by a sintered member, and the motor substrate for the bearing unit is provided. And coupling of the stator core is realized by coupling including a plastic flow coupling part in which the motor board and the stator core are fitted to the housing part, and the housing part is pressed to cause plastic flow, thereby generating a compression force on the mating mating surface. A small motor characterized by: 6. The stator core according to claim 5, wherein:
A small motor characterized by being formed by laminating steel plates subjected to press punching. 7. A small motor according to claim 5, wherein said motor substrate is formed of a steel plate whose connection hole is press-punched. 8. A small motor according to claim 5, wherein a pressing groove having an inclined surface is formed on the pressing surface of said housing portion. 9. A small-sized motor according to claim 1, wherein said rotor portion is formed by connecting a rotor case to a rotating shaft by a plastic flow coupling method. 10. A stator unit in which a stator core in which a coil is wound around a bearing unit rotatably supporting a rotating shaft and a motor substrate are connected, and a rotor case on which a magnet is mounted is connected to rotate integrally with the rotating shaft. In the method of manufacturing a small motor having a rotor unit, a motor substrate and a stator core are coupled to the bearing unit by fitting the motor substrate to the bearing unit and pressing the bearing unit to cause plastic flow. This is realized by a plastic flow coupling method that generates a compressive force on the butting surface, and thereafter, a plastic core that generates a pressing force on the mating butting surface by fitting the stator core to the bearing unit and pressing the bearing unit to cause plastic flow. A method for manufacturing a small motor, which is realized by a fluid coupling method. 11. A method according to claim 10, wherein the plastic flow of the bearing unit is generated by pressing an inclined surface of a pressing groove formed in the bearing unit with a mold punch. 12. A method for manufacturing a small motor according to claim 11, wherein a tip end surface of a cutting edge of said die punch has a plurality of inclined surfaces having different slopes.