JPH0674257A - Manufacture of rotor for electromagnetic clutch - Google Patents

Abstract

PURPOSE:To provide a rotor manufacturing method facilitating the compactness of a rotor with little magnetic leakage using a small number of part items without requiring centering so as to suppress the production of off-specification products. CONSTITUTION:A soft iron plate is punched into circular shape by press working. The center of disc material is then punched by press working, and the middle part is. recessed by cold forging. The middle part of the recessed part is then protruded onto the open side by cold forging to form a protruding part 20. The inner peripheral side and outer peripheral side are bent into cylinder shape by cold forging to form an inner wall 8 and an outer wall 9. A copper ring is placed in a bottom part 11, and copper is fused by heating so as to let the copper flow into the grooves 21a, 21b of the bottom part 11. Upon being cooled down, non-magnetic material 12 formed of copper is diffusion-jointed into the grooves 21a, 21b. Unnecessary parts are cut off by cutting, and a friction face 10a is formed by cutting, With this cutting, the non-magnetic material 12 is exposed onto the friction face 10a side so as to form magnetic cutoff parts 12a, 12b at a rotor 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an electromagnetic clutch rotor which attracts an armature by magnetic force.

[0002]

2. Description of the Related Art A conventional electromagnetic clutch is shown in FIG. The electromagnetic clutch 100 includes a ring-shaped electromagnetic coil 101,
A rotor 1 having a U-shaped cross section including the electromagnetic coil 101
02 and the armature 103 attracted to the rotor 102 by the magnetic force generated by the electromagnetic coil 101.
In order to increase the attraction force between the rotor 102 and the armature 103, the armature 103 has a magnetic cutoff groove 104 formed in the middle portion thereof, and the friction wall 105 of the rotor 102 has a magnetic cutoff groove 104 of the armature 103.
At the positions corresponding to the inner and outer peripheral sides of the
6 is formed, and the magnetic path formed by the rotor 102 and the armature 103 by this is as shown by the broken line α1.
It is formed in a substantially W shape. In the bridge type rotor 102 shown in FIG. 11 described above, a ring-shaped plate material made of a magnetic material is formed into an annular member having a U-shaped cross section by cold forging or the like.
The magnetic shield 106 is formed on the inner and outer circumferences of 05 by punching with a press. On the other hand, USP 3,712,43
Non-bridge type rotor 10 disclosed in No. 9 specification
As shown in FIG. 12, the reference numeral 2 designates an outer wall 108 and a bottom portion 109 of a magnetic body formed from one ring-shaped plate material by cold forging or the like.
When the bottom part 109 is bent and the bottom part 109 is processed, the middle part of the bottom part 109 is projected inward over the entire circumference to form a ring-shaped projection part 110. Subsequently, the inner wall 107 of the magnetic body formed separately is fixed to the inner circumference of the bottom portion 109 by welding, screws or the like. Then, the non-magnetic material 111 which is heated and melted is arranged in the bottom portion 109, and the non-magnetic material 111 is bonded to the inside of the bottom portion 109. After that, the bottom surface of the bottom portion 109 is cut to expose the nonmagnetic material 111 to the friction surface 112.

[0003]

The bridge type rotor 102 includes the inner peripheral portion 105a of the friction wall 105 and the intermediate portion 1a.
Since there is a connecting portion that connects 05b and the outer peripheral portion 105c, there is a problem that magnetic leakage occurs through this connecting portion. In addition, the bridge type rotor 102
However, it is difficult to downsize the rotor 102 due to the restriction of forming the magnetic interruption portion 106 by punching with a press, and as a result, it is difficult to produce a small electromagnetic clutch. U
Rotor 10 disclosed in SP 3,712,439
No. 2 has a high manufacturing cost due to poor assembly workability and a large number of parts because positioning is required when joining the bent outer wall 108 and bottom 109 members to the inner wall 107. turn into. Further, there is a possibility that a gap will be formed between the bent outer wall 108 and the member of the bottom portion 109 and the inner wall 107. When the gap is formed, the melted non-magnetic material 111 leaks to the outside of the bottom portion 109,
There was a possibility of defective products.

The present invention has been made in view of the above circumstances, and an object thereof is to suppress magnetic leakage, easily reduce the size of a rotor, reduce the number of parts, and eliminate the need for centering work.
An object of the present invention is to provide a method for manufacturing a rotor for an electromagnetic clutch, which is less likely to cause defects.

[0005]

In the method for manufacturing an electromagnetic clutch rotor according to the present invention, a ring-shaped plate material of magnetic material is formed into an annular member having an inner wall, an outer wall, and a bottom portion connecting the inner wall and the outer wall by plastic working. In addition, a bending step of forming a ring-shaped protrusion by protruding the intermediate portion of the bottom portion over the entire circumference toward the open side of the annular member, and a joining step of joining a non-magnetic material in the bottom portion, A technical means including a cutting step of cutting the bottom surface of the bottom to form a friction surface and exposing the non-magnetic material to the bottom surface was adopted.

[0006]

In the bending step, a ring-shaped plate member made of a magnetic material is subjected to plastic working such as cold casting and press working to form an inner wall, an outer wall, and an annular member having a substantially U-shaped cross section composed of a bottom portion connecting the outer wall and the inner wall. To form. When processing this annular member or after performing this processing, a protrusion that protrudes toward the open side of the annular member is formed in the middle of the bottom. In the next joining step, a non-magnetic material is joined to the bottom of the annular member. In the subsequent cutting step, the bottom surface of the bottom is cut to form the friction surface of the rotor. The nonmagnetic material in the bottom portion is exposed to the bottom surface side by cutting during the cutting process for forming the friction surface or before or after the cutting process for forming the friction surface. As described above, the rotor having the magnetic shield portion formed of the non-magnetic material on the inner and outer circumferences of the bottom portion is formed.

[0007]

As described above, in the method for manufacturing the electromagnetic clutch rotor of the present invention, since the inner wall, the outer wall and the bottom are formed by processing one ring-shaped plate material, centering is required. Moreover, the number of parts is small. Therefore, the assembling property is excellent, and the manufacturing cost can be suppressed.
Further, since the non-magnetic material is arranged at the bottom portion formed by bending one ring-shaped plate material, for example, when the melted non-magnetic material is joined to the bottom portion, the melted non-magnetic material leaks to the outside of the bottom portion. Never. Therefore, it is possible to prevent defective products from being generated due to the melted non-magnetic material leaking to the outside of the bottom portion.
Since the magnetic shutoff portion is provided by plastic working without using punching, the rotor can be made smaller than a conventional rotor in which the magnetic shutoff portion is punched. Further, since there is no magnetic material connecting the inner wall and the bottom portion and the bottom portion and the outer wall, a high-performance rotor with less magnetic leakage is formed.

[0008]

Next, a method for manufacturing an electromagnetic clutch rotor of the present invention will be described based on an embodiment shown in the drawings. [Structure of Embodiment] FIGS. 1 to 5 show an embodiment of the present invention, and FIG. 3 shows a sectional view of an electromagnetic clutch using a rotor produced by applying the present invention. The electromagnetic clutch 1 according to the present embodiment is for interrupting the interruption of the rotational power from the engine (not shown) to the refrigerant compressor (not shown). This electromagnetic clutch 1 is roughly classified into a rotor 3 provided with a pulley 2 which is rotationally driven by an engine, a rotary driven body 5 provided with an armature 4 frictionally engaged with the rotor 3, and a magnetic force generated when energized. Armature 4
And an electromagnetic coil 6 for frictionally engaging the rotor 3 with the rotor 3.
The electromagnetic coil 6 is fixed to a magnetic stator 6b via a resin winding frame 6a, and the stator 6b is fixed to a compressor housing H via a disk-shaped stay 6c.

The pulley 2 is joined to the periphery of the rotor 3 by welding, and a multi-stage V-belt (not shown) is wound around the pulley 2. The rotor 3 is rotatably supported via a bearing 7 on the inner circumference, and the inner circumference of the bearing 7 is
It is supported by the housing H of the refrigerant compressor. This rotor 3
Is formed by processing a magnetic metal material such as soft iron. The inner wall 8 is located on the inner peripheral side of the electromagnetic coil 6, the outer wall 9 is located on the outer peripheral side of the electromagnetic coil 6, and the armature 4 is provided.
A friction wall 10 that frictionally engages. The friction wall 10 has a bottom 11 of a magnetic material and magnetic shields 12a and 12b provided on the inner and outer circumferences of the bottom 11. Bottom 11
Has a circular arc-shaped cross section on the side on which the electromagnetic coil 6 is arranged. In addition, the magnetic shields 12a and 12b have the inner wall 8
And a bottom portion 11, and a non-magnetic metal material such as copper that joins the bottom portion 11 and the outer wall 9 to each other, and prevents a magnetic path from being formed between the inner wall 8 and the bottom portion 11 and between the bottom portion 11 and the outer wall 9. . Further, on the outer peripheral side of the friction surface 10 a of the friction wall 10, a non-magnetic friction material 13 that enhances the engaging force with the armature 4 is provided.
Is fitted. Since the side of the bottom portion 11 on which the electromagnetic coil 6 is arranged is formed in an arcuate cross section,
As shown in FIG.
The area (a1) on the a side is the area (b1) on the electromagnetic coil 6 side.
Is smaller than that of the magnetic shield part 12b on the outer peripheral side.
The area (a2) on the friction surface 10a side is set smaller than the area (b2) on the electromagnetic coil 6 side. That is, the relations of a1 <b1 and a2 <b2 are set.

The armature 4 has a friction surface 10 of the rotor 3.
The frictional surface 4a is arranged to face a with a gap and engages with the rotor 3. The armature 4 has a ring shape made of a magnetic material such as iron, and has a magnetic blocking groove 14 formed by a slit in an intermediate portion. The magnetic blocking groove 14 is located substantially at the center of the bottom portion 11 of the rotor 3 which faces the magnetic blocking groove 14. Then, the cross-sectional area (Sn) of the bottom portion 11 of the rotor 3 starting from the magnetic blocking groove 14 of the armature 4
Is the armature 4 as shown in FIGS.
Is larger than the area (c1) of the inner circumference of the bottom 11 of the friction surface 10a starting from the magnetic blocking groove 14 and the area (c2) of the outer circumference of the bottom 11 starting from the magnetic blocking groove 14. That is, the relationship of Sn> c1 and c2 is set. Thereby, the magnetic resistance in the bottom portion 11 can be reduced.

The rotary driven body 5 rotates integrally with the rotation of the armature 4 and drives the input shaft of the refrigerant compressor. The outer ring 16 fixed to the armature 4 with rivets 15 and the rotation of the armature 4 are rotated. It comprises a cushion rubber 17 that allows axial displacement and an inner hub 18 fitted to the input shaft. The outer ring 16 and the inner hub 18 are integrally connected via the cushion rubber 17.

Next, a method of manufacturing the rotor 3 will be described with reference to FIGS. 1 and 2A to 2F. (A) A magnetic metal plate (for example, low carbon steel such as SPCC or SPHC) having a plate thickness substantially the same as that of the friction wall 10 of the rotor 3,
A circular disk material 19a is formed by punching by press punching (punching). (B) The center portion of the disc material 19a is punched by press punching to form a ring-shaped plate material (punching). Next, recess the middle part by cold forging, which is plastic working,
The substantially annular member 19b is formed (bending process). (C) A ring-shaped projecting portion 20 that projects to the open side of the substantially annular member is formed by cold forging over the entire circumference in the middle portion of the recess of the substantially annular member 19b (bending process). (D) The inner peripheral side and the outer peripheral side of the substantially annular member 19b are each bent into a cylindrical shape by cold forging to form the inner wall 8 and the outer wall 9 respectively.
To form (bend processing). By the above, the inner wall 8, the outer wall 9, and the inner wall 8 and the outer wall 9
To form a ring-shaped member 19 including a bottom portion 11 having a protrusion 20. In addition, the protrusion 2 is provided inside the bottom 11.
Two grooves 21a and 21b are formed on the inner and outer circumferences of 0, and these two grooves 21a and 21b are for forming the magnetic shields 12a and 12b. And these two grooves 21
The cross-sectional shape of a and 21b is a shape that widens toward the open side of the annular member 19 by providing the end of the protrusion 20 with a circular arc in cross section. Here, the groove 21a on the inner peripheral side
Is deeper than the groove 21b on the outer peripheral side. (E) In the bottom portion 11 of the annular member 19, a non-magnetic material 22 in which a wire material of a non-magnetic material (for example, copper) having a lower melting point than the annular member 19 is formed in a ring shape is placed.
Is heated together with the annular member 19. Then, the non-magnetic material 22 is melted by heating the entire annular member 19, and the non-magnetic material 12 is poured into the two grooves 21a and 21b of the bottom portion 11. Then, the non-magnetic material 22 that has been melted by cooling (radiating) the annular member 19 is cooled and solidified, and the annular member 19 (for example, iron) and the non-magnetic material 12 (for example, copper) are diffusion-bonded to each other to form the annular member. 19 and the nonmagnetic material 12 are firmly joined (joining step). Here, as an example of the non-magnetic material 22, 5 tin is added to copper.
When bronze containing about 10% is used, it is necessary to heat the annular member 19 provided with the non-magnetic material 22 by about 1080 ° C. Further, at the time of heating and cooling for joining the annular member 19 and the non-magnetic material 12, in order to prevent the annular member 19 and the non-magnetic material 12 from being oxidized, a vacuum or an inert gas (for example, nitrogen gas) atmosphere is used. Do in In this embodiment, an example in which the non-magnetic material 22 is formed by using a wire rod formed in a ring shape, but a granular or powdery material may be used. (F) Unnecessary portions on the inner and outer circumferences of the annular member 19 are removed by cutting, and the bottom surface of the bottom 11 is also removed by cutting to form the friction surface 10a. When forming the friction surface 10a, the groove 21a on the inner peripheral side having a large depth is formed.
Is cut off, and the magnetic shield 12a (nonmagnetic material) on the inner peripheral side is exposed on the friction surface 10a side. Further, when the groove 23 into which the friction material 13 is fitted is formed, the bottom surface of the groove 21b on the outer peripheral side is cut by this, and the magnetic shield portion 12b on the outer peripheral side is cut.
The (non-magnetic material) is also exposed on the friction surface 10a side (cutting step). Then, the friction material 1 is placed in the groove 23 provided in the friction surface 10a.
3 are joined together to complete the rotor 3 shown in FIG.

[Operation of Embodiment] Next, the operation of the electromagnetic clutch 1 will be briefly described. When the electromagnetic coil 6 is energized, the electromagnetic coil 6 generates a magnetic force to attract the armature 4 to the rotor 3. Then, the magnetic path shown by the one-dot chain line α in FIG. 3 is formed, and the armature 4 is attached to the friction surface 1 of the rotor 3.
0a is strongly attracted, and the armature 4 rotates integrally with the rotor 3. As a result, the rotational power of the engine transmitted to the pulley 2 via the V-belt is transmitted to the input shaft of the refrigerant compressor via the rotor 3, the armature 4, and the rotary driven body 5.

[Effects of the Embodiment] In the method for manufacturing the rotor 3 of the electromagnetic clutch 1 disclosed in this embodiment, the inner wall 8, the outer wall 9,
The bottom portion 11 is provided by bending one ring-shaped plate material. Therefore, there is no need for centering, and no need for finish cutting inside the rotor 3, which is conventionally required, and the number of parts can be further reduced. As a result, the rotor 3 can be easily assembled and the manufacturing cost can be suppressed. Bottom 1
Since the non-magnetic material 12 melted in 1 is arranged in the bottom portion 11 formed by bending one ring-shaped plate material, the melted non-magnetic material 12 does not leak to the outside of the bottom portion 11. Therefore, it is possible to prevent defective products from being generated due to the melted non-magnetic material 12 leaking to the outside of the bottom portion 11. Magnetic block 1
Since 2a and 12b are formed by bending and non-magnetic material 12 without using punching, compared to the conventional rotor 3 in which the magnetic blocking portion is punched, the rotor 3
Can be miniaturized. That is, when the magnetic shields are formed by press punching, the minimum gap between the magnetic shields is 0.6 times the plate thickness of the bottom portion 11, but it should be reduced to about 0.3 times in this embodiment. Is possible,
The rotor 3 can be downsized. Inner wall 8 and bottom 1
1. There is no magnetic body connecting the bottom portion 11 and the outer wall 9 respectively. Therefore, the high-performance rotor 3 with less magnetic leakage is formed. Since the electromagnetic coil 6 side of the bottom portion 11 is provided with an arcuate cross section, the bottom portion 11 is separated from the end of the stator 6b of the electromagnetic coil 6 (see arrow β in FIG. 3), and the bottom portion 11 is directly connected to the bottom portion 11. It is possible to suppress a decrease in transmission torque due to leakage of magnetism. Since the electromagnetic coil 6 side of the bottom portion 11 is provided in an arcuate cross-section, the inner wall 8 and the bottom portion 11, the average distance between the bottom portion 11 and the outer wall 9 are separated (see arrow γ in FIG. 3), and the inner wall 8 and the bottom portion 11 and the bottom portion 11 and the outer wall It is possible to suppress the decrease in the transmission torque due to the magnetic leakage at 9. Since the electromagnetic coil 6 side of the bottom portion 11 is provided with an arcuate cross-section, the wall thickness of the groove mold for forming the magnetic blocking portions 12a and 12b can be increased. Therefore, the stress generated in the mold can be reduced, the life of the mold can be extended, and as a result, the cost of the rotor 3 can be suppressed. Since the electromagnetic coil 6 side of the bottom portion 11 is provided with an arcuate cross section, the non-magnetic material 12 and the bottom portion 11 are
The joint area with and becomes large, and the joint strength is high.

[Second Embodiment] FIG. 6 is an explanatory view of a main part of a manufacturing process of a rotor 3 showing a second embodiment. In the present embodiment, when the annular member 19 is formed, the depth of the inner peripheral side groove 21a for forming the inner peripheral side magnetic shield portion 12a in the bottom portion 11 is made shallow to the same depth as the outer peripheral side groove 21b. During the cutting process, when the friction surface 10a is cut, the groove 21a on the inner peripheral side is deeply cut to remove the magnetic shield portion 12a on the inner peripheral side from the friction surface 1.
It is exposed on the 0a side.

[Third Embodiment] FIG. 7 is an explanatory view of a main part of a manufacturing process of a rotor showing a third embodiment. In the present embodiment, first, as shown in (g), an annular member 19 having a U-shaped cross section is formed by cold forging, and then, as shown in (h), an intermediate portion of the bottom portion 11 is formed by cold forging. The ring-shaped protruding portion 20 is formed by projecting the portion over the entire circumference toward the open side of the annular member 19.

[Fourth Embodiment] FIG. 8 is an explanatory view of a main part of a manufacturing process of a rotor showing a fourth embodiment. This example shows an example of a joining process by induction heating. A powdery non-magnetic material 22 of a non-magnetic material (for example, copper) having a lower melting point than that of the annular member 19 is placed in the two grooves 21a and 21b of the bottom portion 11 of the annular member 19, and the magnetic material (for example, low carbon is used). The bottom 11 of the annular member 19, which is steel), is heated by the induction heating device 24. The induction heating device 24 includes the bottom portion 11 of the annular member 19.
Is provided in a ring shape having a U-shaped cross section for covering the annular member 19
Is a device for heating the annular member 19 by generating an induced current in the. Then, the non-magnetic material 22 is melted by the heat generation of the annular member 19 by the induction heating device 24, and then the annular member 19 is cooled to solidify the melted non-magnetic material 22. During this solidification, the non-magnetic material 22 is diffusion-bonded to the annular member 19, and the non-magnetic material 12 (see the first embodiment) formed by solidifying the annular member 19 and the non-magnetic material 22 is firmly bonded.

When the bottom 11 of the annular member 19 is heated and cooled, the annular member 19 is held by the chuck 25 and driven to rotate. The rotation of the annular member 19 suppresses the variation in the molten state and the solidification state of the powdery non-magnetic material 22 and prevents the occurrence of defective melting or the like. In this embodiment, the entire bottom 11 of the annular member 19 is heated by the induction heating device 24. However, a local heating device such as the induction heating device 24 is arranged so as to heat a part of the bottom 11, and the chuck 25 is used to form an annular shape. The member 19 may be rotated so as to heat the entire bottom portion 11. Further, by mixing the powdery non-magnetic material 22 with a flux that prevents metal oxidation, or by applying the flux in the grooves 21a and 21b, it is possible to prevent oxidation of the joint portion. As a result, it is not necessary to perform the bonding step in a vacuum or in an inert gas atmosphere in order to keep the strength of the bonded portion high, and the manufacturing cost can be kept low. However, since oxidation of the annular member 19 cannot be prevented, an inert gas may be blown onto the annular member as necessary. In this embodiment, a powdery material is used for the non-magnetic material 22, but a ring-shaped wire or granular material may be used.

[Fifth Embodiment] FIG. 9 is an explanatory view of a main part of a manufacturing process of a rotor showing a fifth embodiment. This embodiment shows an example of a joining process in which the non-magnetic material 22 is melted and poured into the two grooves 21a and 21b of the bottom portion 11 of the annular member 19 to be joined. In this embodiment, an example using TIG welding (inert gas tungsten arc welding) as a technique of melting the non-magnetic material 22 and pouring it into the two grooves 21a and 21b is shown (a processing example of the outer groove 21b in the drawing). Shown). This T
In the IG welding, the nozzles 26 are welded to the grooves 21a, 2
1b is blown with an inert gas (argon gas, helium gas, etc.), and a high voltage is applied to the tungsten electrode 27 and the annular member 19 to generate an arc between the tungsten electrode 27 and the annular member 19 to form a linear shape. The non-magnetic material 22 provided is melted by the heat of the arc. Then, the melted non-magnetic material 22 is filled in the groove 21a or the groove 21b, and the groove 2
The non-magnetic material 22 (that is, the non-magnetic material 12) is joined in the 1a and the groove 21b.

[Sixth Embodiment] FIG. 10 is an explanatory view of a main part of a manufacturing process of a rotor showing a sixth embodiment. In this embodiment,
An example of a joining process in which the non-magnetic material 22 is melted by using MIG welding (inert gas metal arc welding) and the melted non-magnetic material 22 is poured into the two grooves 21a and 21b to be joined (the outer groove is shown in the figure). 21b shows a processing example). In this MIG welding, the nozzle 26 is welded to the groove 21
Inert gas is blown to a and 21b. At this time, a high voltage is applied to the non-magnetic material 22 which is an electrode and the annular member 19 to generate an arc between the non-magnetic material 22 and the annular member 19, and the heat of the arc melts the non-magnetic material 22. And
The melted non-magnetic material 22 is filled in the groove 21a or the groove 21b, and the non-magnetic material 22 (that is, the non-magnetic material 12) is joined in the groove 21a and the groove 21b. The non-magnetic material 22 which is an electrode is continuously supplied during this MIG welding.

[Modification] In the above embodiment, cold forging is shown as an example of plastic working during the bending step, but other working means such as press working may be used. Although copper is shown as an example of the non-magnetic material, other non-magnetic metal such as aluminum, or non-magnetic resin may be used depending on the application. Also, an example was shown in which the annular member was heated to melt the non-magnetic material in the bottom, or the melted non-magnetic material was poured into the bottom, but non-magnetic metal such as stainless steel was joined to the bottom by friction welding. May be. Although the open side of the bottom portion is provided with an arcuate cross section, it may be provided with a taper shape that narrows toward the open side or a rectangular cross section. The dimensional relationship disclosed in the embodiments is an example, and the present invention is not limited to the dimensional relationship disclosed in the embodiments. Further, the electromagnetic clutch of the refrigerant compressor has been shown as an example, but it can be applied to all electromagnetic clutches that transmit and cut off power, such as a supercharger and an automatic transmission.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a rotor manufacturing process (first embodiment).

FIG. 2 is an explanatory diagram of a rotor manufacturing process (first embodiment).

FIG. 3 is a sectional view of an electromagnetic clutch (first embodiment).

FIG. 4 is a sectional view of a rotor (first embodiment).

FIG. 5 is a front view of the rotor before the friction material is mounted (first embodiment).

FIG. 6 is an explanatory view of a main part of a rotor manufacturing process (second embodiment).

FIG. 7 is an explanatory view of a main part of a rotor manufacturing process (third embodiment).

FIG. 8 is an explanatory view of a main part of a rotor manufacturing process (fourth embodiment).

FIG. 9 is an explanatory view of a main part of a manufacturing process of a rotor (fifth embodiment).

FIG. 10 is an explanatory view of a main part of a rotor manufacturing process (sixth embodiment)
Example).

FIG. 11 is a sectional view of an electromagnetic clutch (prior art).

FIG. 12 is a sectional view of a rotor (prior art).

[Explanation of symbols]

 1 Electromagnetic Clutch 3 Rotor 8 Inner Wall 9 Outer Wall 10a Friction Surface 11 Bottom 12 Non-Magnetic Material 19 Annular Member 20 Projection

Front page continuation (72) Inventor Masafumi Tobayama 1-1, Showa-cho, Kariya city, Aichi prefecture Nihon Denso Co., Ltd. (72) Inventor Yasuhiro Suzuki 1-1-cho, Showa-cho, Kariya city, Aichi prefecture Nidec corporation Within

Claims (1)

[Claims] 1. An annular member made of a magnetic material is formed into an annular member having an inner wall, an outer wall, and a bottom portion connecting the inner wall and the outer wall by plastic working, and the middle portion of the bottom portion is formed into an annular shape over the entire circumference. A bending step of projecting to the open side of the member to form a ring-shaped projecting portion, a joining step of joining a non-magnetic material in the bottom portion, and a friction surface is formed by cutting the bottom surface of the bottom portion,
A method of manufacturing an electromagnetic clutch rotor, comprising a cutting step of exposing the non-magnetic material to the bottom surface.