JPH06320287A - Welding method between members - Google Patents

Abstract

PURPOSE:To maintain working accuracy such as perpendicularity between members to be welded at high accuracy. CONSTITUTION:Projection welding is taken as the welding method and a shaft 72 is welded and fixed to a tabular plate 70 so as to stand upright. In welding, a projection 34' is formed on the plate 70 side and an annular recessed groove 60' is formed on the welding surface corresponding to the position projection 34' on the shaft 72 side. When welding is performed, the projection 34' is abutted on the surface surrounded by the recessed groove 60', these members are pressed between fixed and movable electrodes and a DC current is supplied between the electrodes to perform welding. The projection 34' and the vicinity of the part on which this abuts are melted by the supply of the current and plate 70 and the shaft 72 are welded together. At this time, melt flows into the recessed groove 60' and is prevented from flowing out to the outside. As a result, the plate 70 and the shaft 72 can be welded and fixed together with high prpendicularity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a welding method between members, and more particularly to a welding method capable of maintaining the verticality between members with high accuracy.

[0002]

2. Description of the Related Art Conventionally, a brushless polyphase DC motor has been used as a motor for rotating a magnetic disk drive. This kind of motor is also called a spindle motor, and for example, a stator including a stator coil that generates a magnetic field in an excited state, and a rotor including a rotor magnet that obtains a rotational force by electromagnetic interaction with the magnetic field of the stator coil. , A structure having a sensor for detecting the rotational position of the rotor magnet is well known,
In the spindle motor with such a structure, in many cases,
Rotation control is performed by an electronic circuit formed into a semiconductor chip.

By the way, in such a spindle motor, recently, for example, a small-sized personal computer equipped with a magnetic disk device as a storage medium,
Due to the reduction in thickness, the motor itself is required to be smaller and thinner. The spindle motor shown in FIG. 10 shows an example developed in order to meet such a demand.
The spindle motor shown in the figure is a shaft rotating type having a stationary member 1 and a rotating member 2.

The stationary member 1 includes a bracket 3 having a flange portion 3a formed on the outer periphery thereof and an outer peripheral annular wall portion 3b formed inside the flange portion 3a, and the bracket 3
A hollow cylindrical portion 4 fitted and fixed to a hole 3c formed at the center of the outer peripheral annular wall portion 3b and the hollow cylindrical portion 4
An annular concave portion 5 is formed between and. Further, a step portion 4a is formed on the outer periphery of the hollow tubular portion 4, and the annular stator core 6 is fitted and fixed to the hollow tubular portion 4 such that the lower surface on the inner circumferential side abuts on the step portion 4a. ing.

A stator coil 7 is wound around the stator core 6. On the other hand, the rotating member 2 is rotatably supported by vertically arranging a rotating shaft portion 8a at its center and interposing a bearing 9 in a step-like manner between the rotating shaft portion 8a and the hollow cylindrical portion 4. It has a rotor hub 8. An annular outer wall portion 8b is vertically provided on the outer circumference of the rotor hub 8, and an annular wall portion 8c is provided on the outer circumference of the outer wall portion 8b.

The outer peripheral surface of the outer wall portion 8b and the annular wall portion 8
The ring-shaped rotor yoke 10 is externally fitted and fixed so as to come into contact with the lower end surface of c, and the annular rotor magnet 11 is fixedly provided on the inner peripheral surface of the vertically extending portion 10 a provided on the outer periphery of the rotor yoke 10. There is. In the spindle motor configured as described above, the magnetic disk is mounted on the upper surface of the annular wall portion 8c of the hub 8, and the stator coil 7 is inserted through the flexible printed board 12 that is adhesively fixed in the annular recess 5.
By supplying a predetermined exciting current to the rotor hub 8
To rotate.

However, the conventional spindle motor having such a structure has the technical problems described below.

[0008]

That is, in the above-described conventional spindle motor, for example, the stationary member 1 has a complicated overall shape, and it is difficult to integrally form the stationary member 1. Therefore, the bracket 3 and the hollow member 3 are hollow. The hollow tubular portion 4 is divided into the tubular portion 4 and the hollow tubular portion 4 is press-fitted into the hole portion 3c of the bracket 3, or the press-fitting and an adhesive are used in combination.

However, as mentioned above, the motor is small,
When the thickness is reduced, the thickness of the bracket 3 becomes very thin,
Along with this, the contact area between the bracket 3 and the hollow cylindrical portion 4 becomes small, and it becomes difficult to secure the strength by press fitting or an adhesive. In this case, a flange is provided on the outer periphery of the hollow cylindrical portion 4 to increase the mutual contact area. However, even if such a configuration is adopted, the fixing between the bracket 3 and the hollow cylindrical portion 4 is fixed. The strength was not sufficiently obtained. Such a problem also exists when the bracket 3 is fixed to the mounting base of the magnetic disk device.

By the way, as a means for solving such a problem, for example, it is conceivable to form a protrusion on the bracket 3 and fix the bracket 3 and the tubular portion 4 to each other by, for example, projection welding. However, in the projection welding that simply forms the protrusions, when the protrusions and the members around the protrusions melt, the melt flows unevenly between the bracket 3 and the tubular portion 4, and A problem that the verticality of the rib 4 cannot be ensured is predicted.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a welding method capable of ensuring a high processing accuracy such as verticality between members to be welded. To do.

[0012]

In order to achieve the above object, the present invention forms a protrusion on one of the first and second members to be welded, projecting toward the other member. Then, in the welding method in which the first and second members are sandwiched by the movable and fixed electrodes and a direct current is supplied between the movable and fixed electrodes in a state where the protrusion is in contact with the other member, It is characterized in that either one of the first member and the second member is provided with a concave groove in which the melt flows in association with the protrusion.

Further, the welding method of the present invention comprises a stationary member having a stator core wound with a stator coil attached thereto and a rotating member having a rotor magnet attached thereto, the current magnetic field generated in the stator coil and the rotor. In a spindle motor that rotates the rotating member by electromagnetic interaction with a magnet, the first and second members include a central shaft portion that rotatably supports the rotating member and a mounting base for fixing and supporting the motor. The stationary member composed of a bracket to be fixed is divided, and a plurality of protrusions are formed in one of these members along the circumferential direction, and the one or the other is associated with the protrusion. The concave groove into which the melt flows can be formed.

[0014]

According to the welding method between members having the above-described structure, since the concave groove is provided in relation to the protrusion, when the protrusion and the members around the protrusion are melted, the melted material will be in the concave groove. Is stored in. Further, according to the configuration of claim 2, a small size,
The rotary shaft can be fixed to the bracket of the thinned spindle motor with high verticality.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 shows an example of a spindle motor in which projection welding according to the present invention is adopted. The spindle motor shown in the figure is of a shaft fixed type including a stationary member 20 and a rotating member 21, and the stationary member 20 includes a bracket 22 (first member) divided into two and a rotation of the motor. It has a central shaft portion 23 (second member) as a center.

The bracket 22 has an annular base portion 22a and
It has a circular hole portion 22b provided at the center of the base portion 22a, an outer peripheral wall portion 22c standing on the outer periphery of the base portion 22a, and a flange portion 22d provided at the upper end of the outer peripheral wall portion 22c. By pressing an iron-based flat plate-shaped material, it is formed into a substantially dish shape. The central shaft portion 23 includes a ring-shaped base portion 23a, a cylindrical shaft portion 23b erected on the central axis of the base portion 23a, an annular wall portion 23c provided around the outer periphery of the shaft portion 23b, and an annular shape. It has an annular flange portion 23d provided on the outer periphery of the lower end of the wall portion 23c, and is made by cutting the same iron-based material as the bracket 22, for example.

An annular wall portion 23c is provided on the outer circumference of the central shaft portion 23.
The annular stator core 25 is supported in a fitted and fixed state so as to abut the annular flange portion 23d, and the stator coil 25 is wound around the stator core 25. On the other hand, the rotating member 21 has a rotor hub 27 and a yoke 30. The rotor hub 27 has an annular base portion 27a and a hollow cylindrical portion 27b integrally formed on the inner peripheral surface of the base portion 27a so that both ends thereof project in the vertical direction.
And an annular outer wall portion 27c protrudingly provided on the outer periphery of the base portion 27a.

With the hollow cylinder portion 27b facing the outer periphery of the shaft portion 23b of the central shaft portion 23, a bearing 29 is interposed between these members in a two-step manner so that the rotor hub 27 can be rotated. The part 23 is rotatably supported. A yoke 30 having a through hole 30a at its center is fixed to the lower surfaces of the base portion 27a and the annular outer wall portion 27c of the rotor hub 27.

An annular wall 30b is vertically provided on the outer peripheral side of the yoke 30, and a rotor magnet 31 facing the starter core 25 is fixed to the inner surface of the annular wall 30b. In FIG. 1, the member indicated by reference numeral 32 is the bearing 29.
It is a dustproof cap. In the spindle motor configured as described above, the magnetic disk is mounted on the outer periphery of the base portion 27a of the rotor hub 27, that is, on the upper side of the annular outer wall portion 27c, and the flexible printed board 33 adhesively fixed to the inner surface of the bracket 22 is used. By supplying a predetermined exciting current to the stator coil 26, the rotor hub 27 is rotationally driven.

In the spindle motor having such a structure, the fixed portion A between the bracket 22 and the central shaft portion 23 is fixed.
And the fixing portion B between the bracket 22 and the mounting base 24
The welding method according to the present invention has been adopted respectively,
In this embodiment, the welding method is, for example, projection welding. The projection welding shown in FIGS. 2 to 8 is for welding between the bracket 22 and the central shaft portion 23 of the spindle motor. FIG. 2 is a perspective view of the bracket 22, and FIG. The lower end side perspective view and FIGS. 4 to 7 are detailed views of the welding process. In the projection welding shown in FIG.
As shown in FIG.
However, for example, 6 pieces (preferably 3 pieces or more) are formed.

The protrusion 34 is, for example, 0.2 mm although it varies depending on the condition of the material and thickness of the bracket 22.
The diameter is about 0.1 mm. These protrusions 34 are formed on concentric circles along the outer circumference of the circular hole 22b so as to be equiangularly spaced along the circumferential direction, and are formed simultaneously when the bracket 22 is pressed. It

On the other hand, the annular flange portion 23 of the central shaft portion 23
On the lower surface of d, the protrusion 3 provided on the bracket 22 side
4 in a ring-shaped concave groove 60.
Are formed. The concave groove 60 is formed in a circular shape larger than the diameter of the protrusion 34 so as to be located on the outer periphery of the protrusion 34, and is located on a concentric circle along the outer periphery of the base portion 23a.

Although the concave groove 60 is formed in a perfect ring shape in this embodiment, it may be in a state in which the ring is divided. Further, the groove width and the depth of the concave groove 60 are set according to the volume of the protrusion 34. When performing projection welding, first, as shown in FIG. 4, the central shaft portion 23 (second member) is mounted on the fixed electrode 35 with the top and bottom reversed. The fixed electrode 35 has an annular base portion 3 in which a hole portion 35a through which the shaft portion 23b is inserted is provided in the center.
5b and a ring-shaped electrode portion 35c protruding from the outer peripheral edge of the upper end of the annular base portion 35b.

A support tool 50 is disposed outside the fixed electrode 35, and the support tool 50 extends substantially L toward the outer peripheral side of the support portion 50a supported by the main body of the apparatus and the annular base portion 35b.
It has a positioning portion 50b having a letter cross section. The ring-shaped electrode portion 35c is in contact with the annular flange portion 23d, and the annular wall portion 23 is in contact with the fixed electrode 35 thus configured.
The outer peripheral surface of c is set so as to be in sliding contact with the inner peripheral surface of the ring-shaped electrode portion 35c, and the two surfaces of the ring-shaped electrode portion 35c have a function of positioning and supporting the central shaft portion 23 in a predetermined state. .

Next, as shown in FIG. 5, the bracket 22
The circular hole portion 22b of the (first member) is used as the base portion 2 of the central shaft portion 23.
The end face side is placed on the annular flange portion 23d so as to be fitted to the outer periphery of 3a, whereby the protrusion 34 and
The portion surrounded by the concave groove 60 formed in the annular flange portion 23d abuts. At this time, the position of the flange portion 22d of the bracket 23 is determined such that the outer peripheral end surface of the flange portion 22d contacts the inner peripheral surface of the positioning portion 50b. In this case, if the step portion or the protrusion is provided on the inner peripheral surface of the positioning portion 50b, the bracket 22 can be positioned and supported more easily and easily.

In this state, the bracket 22
Is positioned, the circular hole 2 of the bracket 22
The bracket 2 is formed so that an annular gap δ is formed between the inner peripheral surface of 2b and the outer peripheral surface of the base portion 23a of the central shaft portion 23.
2 and the dimensions of each part of the central shaft portion 23 are set.
When the bracket 22 and the central shaft portion 23 are welded, the gap δ prevents these members from directly contacting each other except the protrusion portion 34 and dispersing the welding current.
In addition to providing the gap δ, a means for interposing an electrically insulating ring in the gap δ, providing an insulating coating, or the like is adopted.

Next, as shown in FIG. 6, the movable electrode 36 is lowered from above the fixed electrode 35. The movable electrode 36 is
It is an annular one having a predetermined positional relationship with the fixed electrode 35, and when the fixed and movable electrodes 35, 36 are set, a predetermined DC current is supplied while applying a predetermined pressure between the electrodes 35, 36. , Projection welding is performed. The pressing force at this time is, for example, about 44 kgf / c.
It is set to about m ² . Fixed and movable electrodes 35, 3
An example of the magnitude of the DC current supplied to 6 and the supply time is
The magnitude of the current is about 4000A, the time is 0.002-
It is 0.005 sec.

When projection welding is performed in this manner, the direct current supplied to the electrodes 35 and 36 is concentrated on the protrusion 34, and the protrusion 34 and the protrusion 3 are quickly formed.
A part of the central shaft portion 23 in contact with 4 is melted, a weld nugget 38 is formed between the bracket 22 and the annular flange portion 23d, and the both are firmly fixed (see FIG. 7).

In such a welding process, the welding method according to the present embodiment has the following remarkable effects. That is, in the welding method of this embodiment, the central shaft portion 23
A concave groove 60 is formed in the annular flange portion 23d so as to correspond to the protruding portion 34 provided on the bracket 22 side. Therefore, when the protruding portion 34 and the members around it are melted, the melted material is stored in the concave groove 60,
It is possible to prevent the flow of the melt from becoming non-uniform and the perpendicularity between the bracket 22 and the central shaft portion 23 from decreasing.

Although not shown in detail, in the spindle motor shown in FIG. 1, an insulating tool is also interposed in the fixing means between the flange portion 22d of the bracket 22 and the mounting base 24 of the hard disk device. Projection welding is adopted, and in this welding, the protrusion and the concave groove are formed in advance on either one of the members to be welded. In this case, the protrusion and the recessed groove do not necessarily have to be formed separately for each member to be welded,
The protrusion and the concave groove may be formed on the same member side.

Now, in the spindle motor configured as described above, the projection welding forming the welding nugget 38 is provided both between the central shaft portion 23 and the bracket 22 and between the bracket 22 and the mounting base 24. Since it is adhered at, even if the motor is made smaller and thinner, sufficient adhesion strength is secured. FIG. 8 shows a second embodiment of the method for welding members according to the present invention, and only the characteristic points will be described below. In the welding method shown in the same figure, the protrusions 34 and the concave grooves 60a, 60 are formed on the bracket 22.
and b. The concave groove is composed of an outer concave groove 60a located outside the protrusion 34 and an inner concave groove 60b located inside the protrusion 34.

Each of the concave grooves 60a and 60b has a circular hole 22.
It is formed concentrically with b and is formed on both sides of the protrusion 34 with the protrusion 34 interposed therebetween. Even with the projection 34 and the concave grooves 60a and 60b formed in this way, the same operation and effect as in the above embodiment can be obtained. In the case of the concave grooves 60a and 60b shown in this embodiment, the outer peripheral portion of each protrusion 34 may have a shape that is partially expanded along the shape of the protrusion 34, The protrusion 34 and the concave grooves 60a and 60b can be formed simultaneously when the bracket 22 is pressed.

FIG. 9 shows a third embodiment of the method for welding members according to the present invention. The welding method shown in the figure employs the same projection welding as that of the above-described embodiment, and when the shaft (second member) 72 is welded and fixed to the flat plate (first member) 70 in an upright manner. It is applied. Upon welding, the projection 34 ′ is formed on the plate 70 side. Further, on the shaft 72 side, an annular recessed groove 60 'is formed on the surface to be welded so as to correspond to the protrusion 34'.

When the plate 70 and the shaft 72 are welded, the projection 34 'is brought into contact with the surface surrounded by the concave groove 60', and these members are clamped by the fixed and movable electrodes, and the electrode This is done by supplying a direct current between them.
Due to the supply of the electric current, the vicinity of the protrusion 34 ′ and the portion in contact with the protrusion 34 ′ is melted, and the plate 70 and the shaft 72
And welding is performed.

At this time, the melt is prevented from flowing into the concave groove 60 'and flowing out of the concave groove 60'. Therefore, the perpendicularity between the plate 70 and the shaft 72 is determined by the processing accuracy of the surface of the outer side portion of the concave groove 60 ′ that contacts the plate 70, and if these contact surfaces are finished with high accuracy, Shaft 72 to plate 70
Can be welded and fixed with high verticality.

In this case, the heat generated by the welding is applied to the protrusion 34 '.
Since it concentrates in the vicinity of and the influence on the outside of the concave groove 60 'is reduced, the verticality can be maintained with high precision also by this. As is clear from the above explanation,
The welding method of the present invention is particularly effective for welding a flat plate member vertically to a rod-shaped member. In this embodiment, the concave groove 60 'is provided on the shaft 72, but the groove 60' may be provided on the plate 70. In such a case, the protrusion 34 'and the concave groove 60' may be provided. Can be simultaneously formed by pressing. Further, the application of the present invention is not limited to a fixed shaft type spindle motor, and for example,
The invention can be applied to a fixing means between a bracket of a shaft rotation type spindle motor and a hollow cylindrical portion, and a fixing means between a bracket and a mounting base of a magnetic disk device.

[0037]

As described above in detail in the embodiments,
According to the welding method for members according to the present invention, the processing accuracy such as the verticality between the members to be welded can be ensured with high accuracy.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a spindle motor to which a welding method according to the present invention is applied.

FIG. 2 is a perspective view showing a formation state of protrusions in the welding method according to the present invention.

FIG. 3 is a perspective view showing a formation state of a concave groove in the welding method according to the present invention.

FIG. 4 is a process explanatory view showing a first embodiment of the welding method according to the present invention.

FIG. 5 is a process explanatory view showing the first embodiment of the welding method according to the present invention.

FIG. 6 is a process explanatory view showing a first embodiment of a welding method according to the present invention.

FIG. 7 is a process explanatory view showing the first embodiment of the welding method according to the present invention.

FIG. 8 is a perspective view showing a formation state of a protrusion and a concave groove in the second embodiment of the welding method according to the present invention.

FIG. 9 is an explanatory diagram showing a third embodiment of the welding method according to the present invention.

FIG. 10 is a sectional view showing an example of a conventional spindle motor.

[Explanation of symbols]

 20 stationary member 21 rotating member 22 bracket 22a flange portion 22b outer peripheral annular wall portion 22c hole portion 23 central shaft portion 23a base portion 23b shaft portion 23c annular wall portion 23d annular flange portion 24 mounting base 25 stator core 26 stator coil 27 rotor hub 28 yoke 31 rotor Magnet 34 Projection 35 Fixed electrode 36 Movable electrode 38 Weld nugget 60, 60 'Recessed groove

Claims (2)

[Claims] 1. A protrusion that protrudes toward the other member is formed on one of the first and second members that are the members to be welded, and the protrusion is in contact with the other member. In the welding method of sandwiching the first and second members with movable and fixed electrodes and supplying a direct current between the movable and fixed electrodes, one of the first and second members is provided with the protrusion. A welding method between members, which is characterized in that a concave groove into which a melt flows is provided. 2. An electromagnetic interaction between a current magnetic field generated in the stator coil and the rotor magnet, comprising a stationary member having a stator core wound with a stator coil attached thereto, and a rotating member having a rotor magnet attached thereto. In the spindle motor that rotates the rotating member by the action, the first and second members include a central shaft portion that rotatably supports the rotating member, and a bracket that is fixed to a fixed supporting mounting base of the motor. The stationary member is divided, and a plurality of the protrusions are formed in one of these members along the circumferential direction, and the concave shape into which the melt related to the protrusions flows into the one or the other. The welding method between members according to claim 1, wherein a groove is formed.