JPH08126290A - Connecting method for yoke - Google Patents

Abstract

PURPOSE: To provide a method for connecting a yoke in which the connecting strength not different from that of prior art can be obtained, and in the case of connecting the yoke, welding splash in a coil containing space can be prevented. CONSTITUTION: A yoke 4 for forming the containing space 10 of a coil 8 is formed of an annular inner yoke 12 opened at the outer periphery, and a hollow cylindrical outer yoke 14 so arranged as to surround the outside of the yoke 12. When the yoke 12 is connected to the yoke 14, the peripheral end of the yoke 12 is perpendicularly abutted to the inner surface of the yoke 14. A laser is emitted from an emitting gun 20 disposed on the outer periphery of the yoke 12 to the emitting position 17 on the outer periphery of the yoke 14 along the radial direction of the yoke 12, the thickness of the yoke 14 is melted to connect the peripheral end of the yoke 12 to the inner surface of the yoke 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a yoke joining method for joining a yoke, which is provided in a motor and defines a space for housing a coil, to another member.

[0002]

2. Description of the Related Art At present, motors such as stepping motors are becoming smaller and lighter one after another, and their yokes are made of thin sheet metal or the like. Along with this, laser welding has come to be used for joining the yokes, which enables more accurate joining than other welding methods such as plasma welding and resistance welding.

FIG. 3 shows a motor 2 having a yoke 4 joined thereto by the above laser welding. This motor 2
Is a cropole type stepping motor, and, as shown in FIG. 4, has two phases of yokes 4 that define a storage space 10 for the coils 8 that surround the rotor 6.
The two-phase yokes 4 are vertically stacked to form a two-layer structure. Each of the yokes 4 has an annular inner yoke 12 having an open outer peripheral surface, and a hollow surrounding the inner yoke 12. The outer yoke 14 has a cylindrical shape. Further, the motor 2 is provided with a mounting flange 16 projecting outward in the radial direction at its lower part, and is fixed to a mounting surface (not shown).

Conventionally, when the above-mentioned yoke 4 is joined, laser irradiation is carried out by irradiating a plurality of irradiation points 17 as shown in FIG. 3 with laser. For example, in FIG.
As shown in the middle enlarged portion A, the inner yoke 12 and the outer yoke 14
When joining and, first, the peripheral end surface of the inner yoke 12 is butted against the inner surface of the outer yoke 14 at a right angle. As a result, an annular temporary joint portion 18 is formed on the upper end surface of the yoke 4, and a plurality of welding points 17 are set on the temporary joint portion 18. Then, a laser is applied to the welding point 17 from an irradiation gun 20 located above the upper end surface of the inner yoke 12, and spot welding is performed to join them.
Further, in order to mount the mounting flange 16 on the lower portion of the motor 2, as shown in the enlarged portion B in FIG.
The lower end surface of the outer yoke 14 is abutted at a right angle to the upper surface of the mounting flange 16 to form the temporary joint portion 19 as described above.
A welding point 17 is set at the boundary between the lower edge of the mounting flange 16 and the projecting surface of the mounting flange 16, the irradiation gun 20 is positioned between the outer peripheral surface of the yoke 4 and the upper surface of the mounting flange 16, and the welding point 17 set above is set. On the other hand, laser irradiation was performed from an oblique direction, and spot welding was performed to join them.

[0005]

However, when the above-mentioned welding is carried out, welding droplets (also called splash) are always generated from the molten portion 21 which is heated and melted by the laser.
A large number of 22 are generated and scattered around them. Therefore, FIG.
When the yoke 4 is joined as shown in the middle enlargement portion A or B, the fusion portion 21 reaches the inner surface of the coil storage space 10, and a large number of welding droplets 22 are generated in the storage space 10 to cause the coil 8 to move. Will be scattered. The welding droplets 22 thus scattered adhere to the surface of the coil 8,
If the wires wound there are fused together to cause an electrical failure, or if they enter between the rotor 6 and the inner yoke 12 to cause abnormal noise, or if this is relatively large. There was a problem of causing malfunction.

The present invention has been made in view of the above circumstances, and an object thereof is to ensure a joint strength comparable to that of the conventional one, and to prevent the generation of welding droplets in the coil housing space during yoke joining. It is an object of the present invention to provide a method of joining yokes that can be prevented.

[0007]

In order to achieve the above object, a method of joining yokes according to the present invention is directed to a yoke member surrounding an annular coil housing space surrounding a rotor. Butt the ends at right angles to the members to be joined,
In a method for joining yokes, which is configured to be melted and joined by laser irradiation, laser is radiated from an outer side in a thickness direction of the member to be joined toward an in-plane direction of the yoke member to melt the entire thickness of the member to be joined. The yoke member is joined to the peripheral end portion.

Preferably, the yoke member is an annular inner yoke whose outer peripheral surface is open, and the member to be joined is a hollow cylindrical outer member arranged outside the inner yoke so as to surround it. A yoke, wherein a laser is radiated from the outer peripheral surface of the outer yoke along the radial direction of the inner yoke to melt the entire thickness of the outer yoke, and the peripheral end surface of the inner yoke is set on the inner surface of the outer yoke. It is to make it join.

Preferably, the yoke member is the outer yoke, and the member to be joined is a plate-like mounting flange disposed on the lower end surface of the outer yoke, and the lower surface of the mounting flange is below the lower surface. From the outer yoke is irradiated with a laser along the axial direction, and the plate thickness of the mounting flange is melted,
The lower end surface of the outer yoke is joined to the upper surface of the mounting flange.

[0010]

The operation of the yoke joining method according to the present invention will be described. A yoke joining method in which a peripheral end portion of a yoke member is butted against a member to be joined at a right angle and is melted by laser irradiation to be joined. In, when the laser is irradiated from the outside in the thickness direction of the members to be joined to the in-plane direction of the yoke member, the portion of the surfaces of the members to be joined which is irradiated with the laser is heated by the laser light and melted. The melted region here is very small, while the melted depth is relatively deep. From this, the member to be welded is melted together with its thickness, and the peripheral portion of the yoke member abutted thereto is also melted, so that the member to be joined and the yoke member are bonded while ensuring sufficient bonding strength. It Further, since the laser is irradiated in the in-plane direction of the yoke member, it is possible to secure a sufficient melting depth inside the yoke member and prevent the melted portion from penetrating the yoke member and being exposed in the coil housing space. Therefore, it is possible to prevent the generation of welding droplets in the coil storage space.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of a yoke joining method according to the present invention will be described in detail below with reference to the accompanying drawings. The present embodiment is a method of joining a yoke member provided in a motor to another yoke constituent member, a motor constituent member, etc. by welding by laser irradiation. Here, the laser to be irradiated is a pulsed Nd-YAG laser, which is irradiated from a dedicated irradiation gun. The connection of this yoke is
Usually, it is performed in the same process of the motor assembling process, and is often performed by one irradiation gun.

FIG. 1 is a perspective view of a motor 2 having a yoke 4 according to this embodiment. In addition, FIG.
FIG. The motor 2 is a cropole type stepping motor as in the conventional case, and its configuration is the same as the conventional one shown in FIGS. 3 and 4. The same components as those of the conventional one are designated by the same reference numerals.

The motor 2 will be described in detail. The motor 2 includes yokes 4 for two phases which are vertically stacked. The two phases of the yoke 4 are formed by vertically stacking two annular inner yokes 12 whose outer peripheral surfaces are open, and further enclosing the outer sides of the two inner yokes 12 to form a hollow cylindrical outer yoke 14. It is arranged and configured. The yoke 4 defines an annular storage space 10 and stores a coil 8 surrounding the rotor 6. Further, the motor 2 is provided with a mounting flange 16 that projects outward in the radial direction at its lower portion, and is fixed to a mounting surface (not shown) or the like.

In the present embodiment, a plurality of irradiation points 17 as shown in FIG. 1 are irradiated with a laser, and the yoke 4 is joined by spot welding. That is, the inner yoke 1
2 and the outer yoke 14, the peripheral end surface of the inner yoke 12 is butted against the inner surface of the outer yoke 14 at a right angle as shown in the enlarged portion C in FIG.
To form. A plurality of welding points 17 are set on the outer peripheral surface of the outer yoke 14 at positions just opposite to the temporary joint portion 18. Then, the irradiation gun 20 is positioned on the outer peripheral surface of the outer yoke 14, and the irradiation gun 20 irradiates the irradiation portion 17 with a laser along the radial direction of the inner yoke 12.

To attach the mounting flange 16, the lower end surface of the outer yoke 14 is butted against the upper surface of the mounting flange 16 as shown in the enlarged portion D in FIG. To form. Then, as in the case described above, a plurality of welding points 17 are set and the mounting flange 16
The irradiation gun 20 is positioned below the lower surface of the laser, and the irradiation spot 17 is irradiated with laser along the axial direction of the outer yoke 14 from the irradiation gun 20.

Further, in this embodiment, as shown in the enlarged portion E in FIG. 2, both peripheral end faces along the joint of the two inner yokes 12 are butted against the central portion of the inner face of the outer yoke 14. The welding spot 17 is set in the same manner as above, and the irradiation spot 17 is irradiated with a laser to be joined. At this time, in this embodiment, the opening 24 is formed in advance in the vicinity of the irradiation position 17 so that the joint portion of the two inner yokes 12 can be visually recognized, so that the accurate irradiation position can be confirmed. ing.

When the laser irradiation is performed as described above, each of the irradiation points 17 irradiated with the laser is heated by the laser beam to form the fusion zone 21. Therefore, on the outer side of the outer yoke 14, a large number of welding droplets 22 are generated from the melting portion 21 and scattered around. Here, the surface area of the fusion zone 21 is extremely small, while the depth of the fusion zone is relatively deep. Therefore, for example, the fusion portion 21 formed in the enlarged portion C
Penetrates through the thickness of the outer yoke 14 and reaches the peripheral portion of the inner yoke 12 that is butted on the side opposite thereto, so that the inner yoke 12 and the outer yoke 14 are joined together with sufficient joint strength secured. To be done.

In particular, in this embodiment, the laser to be applied is applied in the in-plane direction of the outer yoke 14, for example.
Since the depth of the fusion zone 21 is sufficiently secured, the fusion zone 2
It is possible to prevent 1 from being exposed in the storage space 10 for the coil 8, and to prevent welding droplets 22 from being generated in the storage space 10 for the coil 8.

Further, two 0.8 mm SECC steel plates are abutted at right angles to each other, and the laser is irradiated through the thickness of the abutted steel plates as in the present embodiment, and the direct irradiation as in the conventional example. An experiment was conducted to examine the joint strength and the presence or absence of welding droplets on the side opposite to the irradiated surface, when the joint was irradiated with laser, and the results are shown in Table 1 below. As shown in Table 1, it can be confirmed that the bonding strength comparable to the conventional one can be secured. Further, on the side opposite to the irradiation surface, unlike the conventional case, no generation of welding droplets was confirmed.

[0020]

[Table 1]

[0021]

As described in the above embodiments, in the method of joining yokes according to the present invention, the ends of the yoke members are abutted at right angles to the members to be joined, and the yokes are joined from the outside in the thickness direction of the members to be joined. By irradiating the in-plane direction of the member with the laser, it is possible to melt the member to be bonded together with its thickness and bond it to the peripheral edge of the yoke member while ensuring sufficient bonding strength. Further, in the present invention, by irradiating the laser in the in-plane direction of the yoke member, a sufficient melting depth can be ensured inside the yoke member, so that the melted portion is exposed to the inner surface of the coil housing space. It is possible to prevent the generation of welding droplets in the coil storage space.

[Brief description of drawings]

FIG. 1 is a perspective view of a motor including a yoke according to the present invention.

FIG. 2 shows a longitudinal section of the motor of FIG.

FIG. 3 is a perspective view of a motor including a conventional yoke.

FIG. 4 is a vertical sectional view of the motor shown in FIG.

[Explanation of symbols]

4 Yoke 16 Mounting Flange 6 Rotor 17 Irradiation Point 8 Coil 20 Irradiation Gun 10 Storage Space 21 Melting Section 12 Inner Yoke 22 Welding Splash 14 Outer Yoke

Claims (3)

[Claims] 1. A member to be joined (14) is provided with a peripheral end portion of a yoke member (12, 14) defining a storage space (10) for an annular coil (8) surrounding a rotor (6). , 16)
In the method of joining the yoke (4), the yoke members (14, 16) are abutted at right angles to each other, and are melted by laser irradiation to be joined, from the outside in the thickness direction of the joined members (14, 16). Of the yoke by irradiating a laser in the in-plane direction of each of the members to be welded (14, 16) together with the thickness of the members to be joined to the peripheral ends of the yoke members (12, 14). Joining method. 2. The hollow member, wherein the yoke member is an annular inner yoke (12) whose outer peripheral surface is open, and the member to be joined is arranged outside the inner yoke (12) so as to surround it. A cylindrical outer yoke (14), the outer yoke (1
Laser is emitted from the outer peripheral surface of 4) along the radial direction of the inner yoke (12) to melt the entire thickness of the outer yoke (14), and the peripheral end surface of the inner yoke (12) is fixed to the outer yoke. (1
4. The method for joining a yoke according to claim 1, wherein the inner surface of 4) is joined. 3. The yoke member is an outer yoke (14),
The member to be joined is a plate-shaped mounting flange (16) disposed on the lower end surface of the outer yoke (14), and the member of the outer yoke (14) is attached from below the lower surface of the mounting flange (16). The mounting flange (1
The yoke joining method according to claim 1, wherein the lower end surface of the outer yoke (14) is joined to the upper surface of the mounting flange (16) by melting the entire plate thickness of (6).