JPS6260904B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method of manufacturing a molded commutator.

Conventional manufacturing methods simply fix the commutator pieces, so sufficient dividing accuracy cannot be obtained, and grooves are required between the commutator pieces.Furthermore, finishing processing is required for this, and mechanical and electrical , which caused deterioration of chemical properties.

The present invention addresses the above-mentioned drawbacks, and the commutator piece and the inner circumferential wall are positioned as a mold, and a part of the molding tool is press-fitted with the dimensional relationship of interference fit, thereby forming a separation groove as a background surface formed when forming the mold. The purpose is to provide a molded commutator that has improved strength, does not require any machining such as separation grooves, and is chemically and electrically strong.

An embodiment of the method of the present invention will be described below with reference to the drawings. An overview of the manufacturing process of molded commutators is shown in Part 1.
As shown in the figure. First, a large number of commutator pieces 2 are press-fitted into a molded piece 1 (shown in FIG. 1A) formed by machining, as shown in FIG. 1B. Next, this molding material 1 is transferred to a mold, a bearing boss fitting 2a (made of brass) is placed in the center of the molding material 1, and a plastic such as phenol or polyphenylene oxide is placed in the molding material 1. The molded product shown in FIG. 1C is obtained by filling the space in the mold and taking it out from the mold.

Note that the plastic used as the filler is formed into a molded material tablet 3 having a constant volume.

Next, by removing molding worker 1 from the molded product,
A molded commutator 4 shown in FIG. 1D is completed.
Note that the mold commutator 4 can be easily removed from the mold commutator 1 by holding down only the mold commutator 1 and pressing only the mold commutator 4 in the axial direction. Furthermore, by annealing the mold commutator 4 (without baking), the plastic mold material can be made stronger.

Each commutator piece 2 is held at a predetermined pitch by plastic, and the bearing boss fitting 2a is also held at a predetermined position by plastic.

Mold commutator 4 molded in this way
By cutting the outer circumferential surface and both end surfaces by machining, the outer circumferential surface and both end surfaces of the commutator piece 2 are finished, and the molded commutator 4' shown in FIG. 1E is obtained.
is formed. This molded commutator 4' can be used as it is as a commutator for small commutator motors for cleaners and mixers.

The above is an outline of the manufacturing of the molded commutator 4', and next, a method of manufacturing the commutator piece 2 will be described with reference to FIG.

A round copper wire is pulled out to form a hoop material for a commutator piece having a cross-sectional shape as shown in FIG. 2A. A commutator piece 2' is obtained by cutting this into a predetermined length. The commutator piece 2' is pulled out with a die, etc., but the head 5 may become asymmetrical (θ, θ') with respect to the center due to warping during pulling out, or a defective shape 6 may occur on one side. There is.

If such commutator pieces 2' with defective dimensions and shapes are discarded and only those that meet the specifications are selected and used, the yield of materials will be poor.

Therefore, all of the commutator pieces 2' are corrected using correction dies 8, 8' during the work process of cutting the hoop material to a predetermined length as shown in FIG. , a commutator piece 2 (shown in FIG. 2C) meeting the specifications is completed. Thereby, the yield of commutator pieces 2 is improved to almost 100%.

Here, the cross-sectional shape of the commutator piece 2 will be described in detail.

The commutator piece 2 is composed of a head part 5, a tail part 9, and a neck part 7 connecting the two parts. The head 5 has a stepped trapezoidal shape.

The dimensions of each part of the commutator piece 2 differ depending on the small commutator motor used, but in the case of a household crane motor (300W to 600W), it was designed to have the following dimensions.

The maximum width A on the outer peripheral side of the head 5 is 2.54 mm.
(Number of commutator pieces: 28), R is 14.7mm, distance r is 0.3
mm, _A0 dimension is 0.09mm, _A1 dimension is 0.95mm, _A2 dimension is
0.81mm, _A3 dimension is 1.76mm, _A4 dimension is 1.3mm, _A5 dimension is 4.54mm.

The reason why the width of the neck portion 7 is made smaller than that of the tail portion 9 is to sufficiently withstand the centrifugal force generated by the high speed rotation of the molded commutator 4 (reaching 30,000 rpm).

That is, since the plastic filler is packed on both sides of the neck 7, the centrifugal force exerted on the commutator bar 2 is reliably absorbed by the tail 9. The circular shape of the tail also prevents stress concentration.

The reason why the outer circumferential surface of the head 5 is not formed into a circular circumferential surface with the dimension R but is formed into a flat shape is to facilitate the press-fitting of the commutator piece 2 into the molding part 1. This will be explained later.

The reason for adding r to both corners of the outer peripheral side of the head 5 is as follows.
The purpose is to facilitate the press-fitting of the commutator piece 2 into the molding tube 1 and to reduce the force applied to the molding tube 1 during press-fitting, and will be described in detail later.

The steps 11 are formed on both sides of the head 5 to facilitate the press-fitting of the commutator 2 into the molding tube 1, to reduce the force applied to the molding tube 1 during press-fitting, and to connect the armature winding to the riser section. The purpose is to ensure that the end portions are press-fitted and fixed securely.

Next, the internal shape of the molding tool 1 into which the commutator piece 2 is press-fitted will be described in detail with reference to FIG.

The molding tube 1 is composed of a cylindrical tube portion 12 made of steel and protrusions 13 formed at equal pitches on the inner peripheral surface of the tube portion 12. The number of protrusions 13 is the same as the number of commutator pieces, for example, 28 pieces.

The protrusion 13 extends parallel to the axial direction of the cylindrical portion, but is formed shorter than the entire length of the cylindrical portion 12.
Therefore, a protrusion step 14 is formed on one of the inner circumferential surfaces of the cylindrical portion 12 .

The height H ₁ of the protrusion step 14 is 3.9 mm, the length H ₂ of the protrusion 13 is 12.1 mm, and the height D of the protrusion 13 is 1.7 mm.

Both corner portions of the protrusion 13 on the side of the protrusion step portion 14 are chamfered. The chamfer angle _θ2 is 30°,
The dimension d is 0.1-0.2 mm. Also, the protrusion step 14
The inner peripheral surface of the cylindrical portion 12 on the side is chamfered, and the chamfer angle _θ1 is 5°. Further, the riser side of the protrusion step portion 14 is inclined at an angle of 30° _θ3 toward the center. As a result, the ends of the completed commutator grooves have an inclined shape.

This is also to ensure the strength of the riser portion of the finished product and to make it easier to remove dust in the groove with a rotating buff. The base of the protrusion 13 is not at a right angle,
A curved surface r' is formed. The radius of this curved surface r′ is 0.3
mm.

The dimension between both protrusions 13 is formed to be slightly smaller than the maximum width A (2.54 mm) of the commutator piece 2. Further, the width dimension of the protrusion 13 is 0.5 to 0.8 mm.

The commutator piece 2 is press-fitted between the protrusions 13 of the molding tool 1 having the above-described structure and then molded with plastic. The commutator 2 is press-fitted from the protrusion step 14 side.

Next, the press-fit state is shown in Figures 4 to 5.
This is explained in detail with a diagram.

A to G in FIG. 4 show each stroke of the press-fitting device for press-fitting the commutator piece 2 into the molding piece 1.

The upper and lower slide rings 15 of the press-fitting device have bearings 16
It is supported by a so that it can slide up and down. 21 is a spring. An index piece 16 for temporary press-fitting is provided inside this upper and lower slide ring 15.

The index piece 16 is provided with a groove 17 on its outer periphery into which the commutator piece 2 is inserted. The number of grooves 17 is the same as the number of commutator pieces. The height of the groove 17 is the commutator piece 2
It is sufficiently higher than the height of the

The depth dimension of the groove 17 is the depth dimension of the commutator piece 2.
It is the same or slightly longer than a ₅ (4.54mm). The protrusion 18 forming the groove 17 has its tip side cut off, leaving a portion (dimension W) on the lower side. A part of this lower side becomes the fixing wall 19 of the commutator piece 2. The dimension between both fixing walls 19 is equal to or slightly larger than the maximum width A (2.54 mm) corresponding to the outer peripheral surface side of the head 5 of the commutator piece 2.

Further, a through window 20 is formed in the upper and lower slide rings 15 to allow the commutator piece 2 to pass through from the horizontal direction.

First, as shown by arrow P in FIG. 4A, the commutator piece 2 is inserted into the groove 17 of the index frame 16 through the through-hole 20 of the upper and lower slide rings 15. Since the commutator piece 2 is inserted from the tail part 9, the tail part 9 is inserted into the groove 1.
7, and the head 5 is placed on the outer circumferential side.
Both side surfaces of the head 5 abut against the fixing wall 19, whereby the commutator piece 2 is held within the groove 17 of the index top 16.

The index top 16 is rotated one pitch at a time, the commutator pieces 2 are inserted as described above, and the commutator pieces 2 are inserted and held in all the grooves 17 of the index top 16.

After this, the molding machine 1 and the index frame 16, which have been supported in advance on the transfer arch 22,
alignment and pitch alignment (index frame 1)
6 and the projection 13 of the molding tool 1) as shown in FIG. 4B, and the press head 23 is lowered as shown in FIG. 4C, the transfer arch is pressed against the spring 24. Yak 22 and Molder 1 descend.

The molding worker 1 descends and the upper and lower slide rings 15
When the molding ring 1 comes into contact with the molding ring 1, the upper and lower slide rings 15 descend against the spring 21. Note that the index top 16 does not fall and remains in the same state. For this purpose, the upper part of the commutator piece 2 is press-fitted into the groove between the protrusions 13 of the molding piece 1.

In addition, in the press-fitting process shown in FIG. 4C, not all of the commutator pieces 2 are press-fitted into the molding piece 1.

That is, the lower end of the molding tool 1 is stopped at a position that is higher than the lower end of the groove 17 of the index piece 16 by a distance a. The dimension a corresponds to the unpress-fitted height. Therefore, a gap _W0 is created between the upper end of the fixing wall 19 of the index frame 16 and the lower end of the protrusion 13 of the molding tool 1 (on the side of the protrusion step 14).

It is necessary to stop the molding tool 1 from descending when this gap W ₀ is left in order to prevent the lower end of the protrusion 13 from touching the upper end of the fixing wall 19. When you touch it,
This is because the lower end of the protrusion 13 and the fixing wall 19 will be damaged.

In this state, the commutator piece 2 is strongly press-fitted between the protrusions 13 of the molding tool 1, so when the press head 23 is raised, as shown in FIG. 4D,
The commutator piece 2 is held in the molding tool 1 and pulled out from the index piece 16.

The transfer arch 22 is raised to its original position by the spring 24, and the molding gear 1 is also raised while holding the commutator piece 2. Further, the upper and lower slide rings are also raised to their original positions by springs 21.

Next, as shown in FIG.
6 in the horizontal direction, and replace it with the main press-fitting piece 2.
5 (or move the vertical slide ring 15 containing the molding ring 1 to the upper side of the main press-fitting piece 25).

In this state, by lowering the press head 23 as shown in FIG. 4F, the molding worker 1 is lowered to the side of the main press-fitting piece 25.

The commutator piece 2 held by the molding tool 1 descends along the guide protrusion 26 of the main press-fitting piece 25, and descends to the lower step 27 of the guide protrusion 26. The commutator bar 2 cannot now descend any further, but the press head 23 continues to descend, so that the forming tool 1 itself is pushed down. For this reason, all commutator pieces 2 are press-fitted into the molding part 1,
When the press head 23 reaches the upper end position of the guide protrusion 26, the descent of the press head 23 is completed.

As described above, the press-fitting of the commutator piece 2 into the molding member 1 is completed, and when the press head 23 is then raised to the original position as shown in FIG. The press-fitted molding tool 1 is raised to its original position while being supported. Thereafter, the molding machine 1 is taken out from the transfer chuck 22 by pitch conveyance, and preparations for transfer to the plastic molding process are completed.

In the final press-fitting process shown in FIG. 4F, in addition to the final press-fitting of the commutator piece 2 into the molding piece 1, correction of both cut end faces of the commutator piece 2 is also performed at the same time.

That is, both ends of the commutator 2 are as shown in FIG.
The cut end will be distorted as shown in A′. In other words, an inclined portion having a dimension d is formed on both cut surfaces. Therefore, the actual size of the commutator piece 2 cut to size L is L+ ^d .

Since the axial length of molding member 1 is L, the fourth
In the process shown in F in the figure, both cut end surfaces of the commutator piece 2 are pressed by the press head 23 and the lower end 27 of the guide protrusion 26, and as shown in C in FIG. Corrected for length. B in Figure 5
shows the dimensions and shape of the commutator piece 2 after correction, and C' in Fig. 5 shows the shape of the end face after correction.As is clear from this, the end face is formed almost flat. It is.

In this way, when the commutator piece 2 is completely press-fitted into the molding part 1, the end face is corrected, so the length of the commutator piece 2 becomes constant, and the length of the commutator piece 2 becomes constant.
This eliminates variations in the height L of the commutator pieces due to variations in the longitudinal dimensions of the mold, and the amount of resin filled in the mold becomes uniform. In addition, even if the weight of the weighed molding tablet 3 is uneven and the weight is particularly large, the molding tablet 3 may be weighed as described below.
Since the resin escapes to the stepped flat part on the outer periphery of the commutator, the axial dimension of the commutator after molding becomes constant. Further, due to this resin escape, a predetermined pressure can be obtained during compression molding, resulting in molding with stable mechanical strength.

Next, the effect regarding the molding employment 1 mentioned earlier,
Describe the effects in detail.

Since the commutator pieces 2 are press-fitted from the index piece 16 into the molding part 1 all at once, the life of the protrusion 13 of the molding part 1 is significantly extended.

That is, when the commutator piece 2 is press-fitted, a strong stress is applied to the side surface of the protrusion 13 of the molding piece 1. However, since the commutator pieces 2 are inserted between the respective protrusions 13 at the same time, the protrusions 13 are pressed by the commutator pieces 2 from both sides. Therefore, the stress applied to both sides of the protrusion 13 acts in a direction of canceling it out, so that the life of the protrusion 13 can be maintained for a long time. That is, it can withstand long-term use.

Since the protrusion 13 of the molding part 1 has a curved surface r' formed at its base, it has a reinforcing structure. Therefore, even if a biased side stress is applied to the protrusion 13 when the commutator piece 2 is press-fitted, the protrusion 13 can sufficiently withstand the stress.

Protrusion 1 corresponding to the protrusion step 14 side of molding part 1
Since both corner portions 3 are chamfered, the commutator piece 2 can be easily press-fitted. That is, the maximum width A of the head 5 of the commutator piece 2 is
Although the projection 13 is formed slightly larger than the dimension between the projections 13 and 3, since both corners of the projection 13 are chamfered, press-fitting properties are improved. In addition, if there are no corners, not only will the press-fit performance be significantly reduced, but the corners will also cause
Since the commutator piece 2 is made of copper material, it is cut away. When the commutator piece 2 is shaved, the surface pressure between the commutator piece 2 and the protrusion 13 decreases, and the plastic mold material is removed from the commutator piece 2.
There is a possibility that the liquid may flow into the joint surface of the protrusion 13, which is undesirable.

Cylindrical part 1 corresponding to the protrusion step part 14 side of the molding part 1
Since the inner peripheral surface of No. 2 is chamfered θ ₁ ,
Press-fitting of the commutator piece 2 is easily performed.

The chamfer θ ₁ on the inner circumferential surface of the cylindrical portion 12 and the chamfer θ ₂ on the corner of the protrusion 13 not only facilitate press-fitting the rectifying piece 2 into the molding member 1 but also have the following advantages.

That is, the commutator piece 2 is indexed to the index piece 16.
When moving from to molding job 1, index piece 1
Even if the commutator piece 2 held at the molding part 6 does not fit perfectly directly above the protrusions 13 of the molding part 1, the commutator part 2 can be smoothly attached to the molding part 1 due to the chamfering of the molding part 1. It is press-fitted into the

Further, the fixing wall 19 of the index piece 16 is for holding the commutator piece 2 in a predetermined position.
Since the commutator piece 2 is positioned here, its insertion into the molding tube 1 is ensured.

Furthermore, in order to increase the mechanical strength of the protrusions 13 of the molding tool 1, by narrowing the width between the protrusions 13, it is possible to increase the width of the protrusions 13 by that amount. However, if the width between the protrusions 13 is narrowed, the commutator pieces 2
The width must be made narrower accordingly. If it is narrowed, it will affect the rectification period of the commutator, causing deterioration of rectification.

Generally, in the case of a commutator motor for a cleaner, the spacing between commutator pieces is approximately 0.5 mm to 0.8 mm. In terms of performance as a commutator, the width of the protrusion 13 of the molding member 1 is naturally determined. Therefore, protrusion 1
In order to increase the mechanical strength of 3, a curved surface is provided at the base of the protrusion 13.
It is necessary to provide r′.

Next, the function and effect of the commutator bar 2 will be described in detail.

When the commutator piece 2 is inserted into the molding tube 1, the curved surface r of the head 5 of the commutator piece ₂ comes into contact with the molding tube 1 within the dimension a1 of the side surface.

The reason why the outer circumferential surface of the head 5 does not come into contact with the _a2 dimension range of the side part is to minimize the contact area with the molding member 1 to reduce the insertion force. This will be part 11. On the other hand, the thickness of the head of the _A1 section was increased to allow for stable press-fitting of the end of the armature winding into the riser section. That is,
To fix the end of the armature winding by press-fitting, a recess is formed in the riser part of the outer periphery of the commutator piece 2 of the finished molded commutator 4', and after the end of the winding is inserted into the riser part, the end of the winding is inserted into the riser part. Both sides of the coil are crushed and fixed by plastic deformation, and electrical and mechanical connections are made between the winding ends and the commutator pieces.

Next, the functions and effects associated with molding the mold commutator 4 and subsequent machining will be described in detail.

The molded commutator 4 has grooves formed on both sides of the commutator piece 2. This groove is formed by the protrusion 13 of the molding chamber 1 during molding into the mold commutator 4 in the molding chamber 1 . At this time, the portion of the protrusion 13 is not filled with plastic molding material, so a groove remains.

Mold commutator 4 formed by such a method
Since grooves are automatically formed on both sides of the commutator piece 2 during molding, there is no need to perform post-processing to form grooves on the molded commutator 4 taken out from the molding tool 1.

Machining the grooves requires removal of copper chips from the commutator bar 2. A short circuit between the commutator pieces 2 due to residual chips and a burnout of the motor due to this are likely to occur. Plastic molds, which normally do not absorb moisture on the surface, can absorb moisture because the mold part is also cut during machining. Plastic molding materials are required to have heat resistance and mechanical strength, which can easily cause insulation deterioration, so it is necessary to use materials mixed with glass fiber, asbestos, and other plastics, which significantly deteriorates machinability. In addition, this causes the tool bit to wear out quickly and requires maintenance costs.Due to poor machinability, internal stress remains in the plastic mold during processing, reducing durability against heat and centrifugal force, and reducing workability. As a result, the machined surface becomes uneven and fluffy, resulting in problems such as a significant decrease in the ignition resistance of the plastic mold part due to the arc generated during abnormal rectification.

However, according to the method of the present invention, such problems can be solved at once.

Regarding the present invention, on the riser side of the molded commutator 4', there are no grooves on both sides of the commutator piece 2, and the plastic molding material is filled up to the point flush with the outer peripheral surface of the commutator piece 2. The ends of the motor windings connected to the riser section are press-fitted and reinforced from the lateral direction.

That is, since the protrusion 13 of the molding part 1 does not exist over the entire length of the cylindrical part 12, the protrusion step part 14 can be formed on one side of the interior of the cylindrical part 12. Therefore, the plastic molding material is filled in the protrusion step portion 14, and no grooves are formed on both sides of the commutator piece on the riser side due to the filling of the plastic molding material. The end portion of the armature winding is press-fitted into the riser portion of the commutator bar 2 as described above. At this time, the riser side of the commutator piece 2 is covered with plastic molding material on both sides.
Since the commutator piece 2 is filled with the same amount as the outer circumferential surface of the coil, the commutator piece 2 is not deformed or damaged by the external force received when the winding end is press-fitted, and the winding end can be securely fixed.

In the molded commutator 4 taken out from the molding machine 1, a curved surface r remains at the outer peripheral corner of the head 5 of the commutator piece 2. This molded commutator 4 is finished as a molded commutator 4' by machining, so that the curved surface r is eliminated. That is, since the outer periphery of the commutator piece 2 is cut by machining, the curved surface r is eliminated. Therefore, the commutator area of the commutator piece 2 increases, and the rectification characteristics are not adversely affected.

In general, molded commutators have the disadvantage that the plastic mold is carbonized by sparks from the carbon brushes generated during abnormal commutation, resulting in a decrease in its mechanical strength, and the commutator pieces may bulge out or be damaged.

However, according to the invention, the protrusion 1 of the molding part 1
Since the height D of 3 is made higher than the dimension _a1 of the head 5 of the commutator piece 2, the groove can be deepened accordingly. Since the mold surface is formed with a thermally and mechanically strong surface, it is less likely to be damaged by abnormal sparks, and its mechanical strength is also improved.

Since the inner circumferential surface of the cylindrical portion 12 and both corners of the protrusions 13 are chamfered, there is no generation of ironing scum (string-like burrs) due to press-fitting of the commutator piece 2, and the commutator piece inside the plastic mold part is chamfered. It is possible to eliminate short-circuit accidents or insulation defects between the two. Since the head side of the commutator piece 2 is pressed against the side of the protrusion 13 of the molding member 1 with a predetermined pressure, the plastic molding material passes between the head side of the commutator piece 2 and the protrusion 13 and presses against the side of the protrusion 13 of the commutator piece 2. There is no leakage to the outer periphery.

Therefore, since no burrs are generated on the outer circumferential side of the commutator piece 2, there is no need for deburring after the commutator is formed.

Next, the internal processing of the molding tool 1 will be described with reference to FIG.

The internal shape of the molding tool 1 is complex, as shown in FIG. 6A, and requires high precision. Especially the protrusion 1
3. Unless the spacing, pitch, and thickness of the parts are uniform throughout, a high-quality product cannot be produced.

Therefore, the molding part 1 can be easily formed by making it completely open so as to pass through it vertically and by broaching it.

As shown in FIG. 6C, the molding tool 1 is held on a broaching table 30, and a broaching die 31 shown in FIG. 6B is passed through the molding tool 1 to obtain the dimensional accuracy of the protrusion 13.

Next, the outer shape of the molding tool 1 will be described with reference to FIG.

A flat part 32 and a stepped flat part 33 are provided on the outer periphery of the cylindrical part 12 of the molding tool 1.

The stepped flat portion 33 is formed on the transfer arch 22 during the press-fitting process of the commutator piece 2 shown in FIG.
It functions when holding the molded part 1. That is, since the stepped flat portion 33 is received by the transfer arch 22, the molding article 1 is securely held on the transfer arch 22.

The flat portion 32 and the stepped flat portion 33 also serve as an escape for excess mold material during plastic molding.

That is, the plastic mold of the molding member 1 into which the commutator piece 2 has been inserted is placed into a mold consisting of a lower cavity 34, an upper cavity 35, an upper molding punch 36, and a lower molding punch 37, as shown in FIG. 7C. . The bearing boss metal fitting 2a also has a lower forming punch 37.
Protected by In this way, the plastic molding material is molded and poured as shown in light black in FIG. 7C. As a result, the plastic molding material fills the space within the molding chamber 1. Since the doublet 3, which is a plastic molding material, has a somewhat larger volume than the space, the excess tablet 3 flows out from the upper and lower surfaces of the molding chamber 1 into the flat portion 32 and the stepped flat portion 33.

The reason for using a tablet with a somewhat large volume is to take into account the fact that the space in the molding chamber 1 into which the commutator pieces 2 are inserted varies slightly depending on the space.

Furthermore, unless the plastic molding material is filled into the space with a certain pressure, the molded parts will be dense and dense, making it impossible to produce a product of good quality. Therefore, by using a multi-diameter tablet, the excess material filled with a constant pressure during molding is released into the flat part 32 and stepped flat part 33 of the molding tool 1. Gas also escapes at this time.

In other words, the flat portion 32 and the stepped flat portion 33 are necessary to produce a high quality product.

As described above, according to the method of the present invention, the plastic molding material is
The press-fitted part between the stepped part of the commutator piece and the molding protrusion is not filled at all, and the dividing precision of the molding protrusion can be reproduced as is, and the separation groove between the commutator pieces is formed by the new molding surface. No groove processing by machining is required, and a high-quality molded commutator can be manufactured extremely easily.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, in which Fig. 1 shows the manufacturing process of a molded commutator, Fig. 2 shows a process of correcting the shape of a commutator piece, and Fig. 3 is a perspective view showing the internal structure of the molding machine. Figure 4 shows the process of press-fitting the commutator piece into the molding tube, Figure 5 shows the process of correcting the shape of both ends of the commutator piece, Figure 6 shows the internal processing of the molding tube, and Figure 7 indicates the external shape of the molded part. 1... Molding employment, 2, 2'... Commutator piece, 3
...Plastic molding material (tablet),
4, 4'...Mold commutator, 13...Protrusion.

Claims (1)

[Scope of Claims] 1. A plurality of commutator pieces are inserted and held between a large number of protrusions formed at equal pitches on the inner periphery of a molding groove, and plastic is inserted between the commutator pieces and the protrusions in the molding groove. In the method of manufacturing a molded commutator by filling molding material to form a molded commutator in a molding tube, removing the molded commutator from the molding tube, and finishing the outer periphery of the molded commutator, a die is formed from the hoop material. It is pulled out and has a cross-sectional shape with a press-fit stepped part limited to a part of the press-fit head, and cut to form a commutator piece. Hold the press-fit position, press-fit the commutator piece press-fit stepped part, the inner periphery of the molding part, and both sides of the protrusion in a dimensional relationship for interference fit,
The molded commutator is characterized in that the molding tool holding the commutator pieces is then put into a mold, and after molding, the finished product is taken out from the molding tool, thereby eliminating the need for subsequent groove machining. Production method.