JP3391200B2 - Manufacturing method of mold yoke for stepping motor - Google Patents

Description

BACKGROUND OF THE INVENTION [0001] [Technical Field of the Invention The present invention relates to a stepping motor, and particularly high characteristics of the motor, a method of manufacturing a scan stepping motor mold yoke attained low cost Things. 2. Description of the Related Art FIG. 11 is a sectional perspective view showing the structure of the above-described stepping motor. First, the schematic structure of the stepping motor will be described with reference to FIG. According to FIG. 1, a rotor 1, which is a rotating body, comprises a ring-shaped permanent magnet 2 multipolarly magnetized in a circumferential direction and a shaft 3 for supporting the same, and a stator is formed so as to surround the outside thereof. Have been. The stator includes a permanent magnet 2, yokes 4, 5, 6, and 7 having four opposing surfaces in total, and two upper and lower exciting coils 10, 11 mounted on the outside thereof.
The stepping motor of the present stepping motor is provided with an outer cylinder portion 8 in which these parts are interposed, and a cap 9 for closing the outer cylinder portion 8.
The magnetic pole teeth a of the yokes 4 and 5 constituting the phase and the magnetic pole teeth a of the yokes 6 and 7 constituting the B phase have a predetermined electrical angle (90
゜) to form a two-phase stepping motor. FIG. 12 is a perspective view of the yokes 4, 5, 6, 7 in which a plurality of comb-shaped magnetic pole teeth a are provided around a disk-shaped flange b. The yokes 4, 5, 6, and 7 focus the magnetomotive force generated by exciting the exciting coils 10 and 11, and the focused magnetic flux is supplied from the magnetic pole teeth a to the rotor 1 Handed over to the side. Conventionally, this type of stepping motor has a yoke 4, 5,
After sequentially interposing the excitation coils 6, 7 and the excitation coils 10, 11 and the like, the assembly is pressed down with the cap 9 and sealed, and all the interposed components are integrally fixed by the pressing. At this time, as shown in FIG. 14, the yokes 5, 5 of the yokes 4, 5 constituting the A-phase and the yokes 6, 7 constituting the B-phase,
And the flange portion b of the yoke 6 are overlapped with each other so as to be opposed to each other on the rear surface, and are interposed in the outer cylinder portion 8. On the other hand, in recent years, OA equipment and the like tend to be light, thin and short, high quality and low cost, and resinization and insert molding are becoming widespread in each product and part.
In order to cope with such a tendency toward miniaturization, resin molding of the yokes 4, 5, 6, 7 and the bearings 14 is becoming popular in the above-mentioned stepping motors. FIG. 13 is a vertical cross-sectional view of a molding die loaded with a yoke in a resin mold. Conventionally, in molding a yoke, as shown in FIG. 13, a plurality of yokes 4, 5, 6, and 7 are sequentially loaded into a molding die K, and these are integrally fixed and molded with a molding resin. . At this time, the yoke 5 is set so that the lower surface of the yoke 5 is supported by the stepped portion K1 of the molding die K and the lower surface of the yoke 6 is supported by the upper surface of the yoke 5. b are closely adhered to each other back-to-back (back-to-back) and molded in a stacked state. However, as described above, when assembling the electromagnetic portion by sequentially interposing the individual parts, the dimensions of the outer cylindrical portion 8 as the outer case, The dimensions of the molding die K are set with a certain margin in consideration of the variation in the processing accuracy of the parts to be set (the variation in the yoke plate thickness is twice as large in this overlapping portion). In any case, play occurs when setting the yoke, and the positional accuracy of each yoke with respect to the stator deteriorates. In addition, due to such backlash and the like, there arises a problem that the quality of the motor becomes unstable, for example, the interior parts vibrate and generate noise when the motor is driven. As described above, each phase (A phase and B phase)
If the yoke that composes (phase) has a structure in which the flanges are in close contact with each other back to back, each phase is magnetically short-circuited, and the other phase is generated by leakage flux when an arbitrary phase is excited. Are magnetized, and the magnetic pole teeth of the non-excited phase are excited. For this reason, the stop position of the rotor 1 (that is, the angular displacement of the rotor 1) determined by the interaction between the magnetic pole teeth of the non-excited phase and the magnetic pole teeth of the excited phase is a theoretical value (2).
In the case of a stepping motor having a phase structure, one-phase excitation and two-phase
(7.5 degrees / step in the phase excitation method and 3.75 degrees / step in the 1-2 phase excitation method), which has a problem of adversely affecting the characteristics (angle accuracy) of the stepping motor. Was. [0011] The present invention is to solve the above problems, and its object is to provide a method for producing a scan stepping motor mold yoke which attained high performance and cost of the motor. That is, according to the first aspect of the present invention, comb-shaped pole teeth are formed on a flange (b) of a molding die (K).
A plurality of yokes (4, 5, 6, 7) provided with (a) are sequentially
After loading while combining, integrated with mold resin
Yoke for stepping motor to be fixedly formed
In the manufacturing method of the above, the inner wall of the molding die (K)
A first step having a step (T) greater than the thickness of the yoke (5)
Section (K1) and a second step section (K2).
(4, 5, 6, 7), facing the back
The yoke (5) among the yoke (5) and the yoke (6)
Is supported by the first step (K1), and
The yoke (6) is supported by the second step (K2).
So that the plurality of yokes (4, 5, 6, 7) are sequentially
The yoke (5) which is loaded into the molding die (K) and faces the back
A gap (G) is formed between the yokes (6).
A molten resin is injected into a mold (K) to form the plurality of yokes.
(4,5,6,7) are integrally fixed with mold resin
And molding the molding between the yoke (5) and the yoke (6).
Forming a non-magnetic layer (12) with a resin or air layer
Characterized in that was. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram of an embodiment of the present invention. FIG. 6 is a view showing a first embodiment of a method for manufacturing a stepping motor mold yoke (hereinafter, referred to as a mold yoke), and is a longitudinal sectional view of a molding die loaded with components. In order to simplify the description, in the following description, the same reference numerals are used for the same parts as those in the related art. In FIG. 1, 4, 5, 6, 7 are yokes,
K1 is a step provided on the key of the molding die K for supporting the yoke 5. 13 is the yoke 5, 6 facing the back
Of the magnetic pole teeth a provided on the flange portion b of the projection, and is formed at, for example, three places on the flange surface. G is a gap formed when the tips of the projections 13 abut against the facing flange b, and shows a state in which the yoke 5 and the yoke 6 do not adhere when components are loaded. The projection 13 is formed by a dowel, a bent claw, or the like. In the method of manufacturing the mold yoke according to the present embodiment, first, the yokes 4, 5,
6 and 7 are set in order. At this time, the projection 13 of the yoke 5 and the yoke 6 abuts against the facing flange b to form a predetermined gap G between the yoke 5 and the yoke 6 according to the amount of projection of the projection 13. Molding mold K closed (mold closing)
Then, the molten resin is injected into the molding die K,
5, 6, and 7 are integrally fixedly molded with a mold resin to form a mold yoke. At this time, a molding resin is poured into the gap G, and the nonmagnetic layer 12 (magnetic gap layer) is formed between the yokes 5 and 6 with the molding resin, or the molding resin is poured into the gap G. Instead, they may be present in a gaseous state and remain in an air layer. As described above, in the first embodiment of the present invention,
The gap G between the yoke 5 and the yoke 6 is defined by the protrusion 13 described above.
In this case, the projection 13 serves as a spacer between the yoke 5 and the yoke 6 and also functions as a cushion material.
The variation in the thickness of the yoke caused by the variation in the processing accuracy is absorbed. Therefore, the yokes 5 and 6 opposed to each other on the rear side are supported by the projections 13 so as not to be in close contact with each other irrespective of the variation in the thickness of the yoke, and a gap (magnetic gap) is formed between the yokes 5 and 6. The positional relationship between the yoke 5 and the yoke 6 with respect to the stator can be accurately set regardless of the variation in the yoke plate thickness. Therefore, if the mold yoke manufactured by the above method is used, each phase (A
Phase and the B phase), the non-magnetic layer 12 is formed, and each phase is magnetically separated by the non-magnetic layer 12, so that even when an arbitrary phase is excited, The inconvenience that the magnetic flux focused on the phase yoke leaks to the yoke of another phase is prevented as much as possible, and even when a large magnetomotive force is generated, the magnetic influence on the non-excited phase is greatly reduced. At the same time, the characteristics (angular accuracy, noise due to vibration, uneven torque, etc.) of the stepping motor are remarkably improved due to the interaction with the buffer effect provided by the projections 13. The formation of the gap G by the projections 13 is not limited to the case of the mold yoke.
Naturally, the present invention can also be applied to a stepping motor which is assembled by interposing individual components in the outer cylindrical portion 8, and an embodiment thereof is shown in FIGS. 6 and 7. FIG. 6 shows the yoke 5 and the projection 1 provided on the yoke 6 facing the back side, similarly to the case of the mold yoke described above.
3A and 3B are examples in which a gap G (in this case, an air layer) is formed by abutting the opposing yokes. FIG. 6A is a curling type stepping motor, and FIG. FIG. 6C shows a stepping motor of a cup type. FIG. 7 shows a projection 16 on the inner wall of the outer cylinder 8.
FIG. 7A shows an example in which a gap G is formed between the yoke 5 and the yoke 6 by interposing the protrusion 16 between the yoke 5 and the yoke 6 opposed to each other when the components are interposed. A curling type stepping motor, FIG. 7B shows a pancake type stepping motor, and FIG. 7C shows a cup type stepping motor. The protrusion 1
Reference numeral 6 is formed by a dowel, a bent claw, or the like. Also in the above method, the characteristics of the stepping motor are remarkably improved by the buffering effect of the projection 16 and the magnetic cutoff effect of the magnetic gap layer formed between the yoke 5 and the yoke 6. FIG. 2 shows a second embodiment of the method of manufacturing a mold yoke according to the present invention, and is a longitudinal sectional view of a molding die loaded with components, as in the case of the first embodiment. In FIG. 2, 4, 5, 6, and 7 are yokes.
K1 is a step provided on the key of the molding die K for supporting the yoke 5. Numeral 12 denotes a non-magnetic inclusion (for example, a resin or non-magnetic steel spacer) which is an elastic body and is interposed so that the yoke 5 and the yoke 6 do not adhere to each other. It is configured such that a non-magnetic layer is formed by the magnetic inclusions 12. By the way, in the method of manufacturing the mold yoke according to the present embodiment, the yoke 4,
5. The elastic inclusion 12 and the yokes 6 and 7 are sequentially set, and the elastic inclusion is introduced by, for example, inviting a slide mold (not shown) during mold clamping or pressing down the mold from above. By slightly compressing and deforming 12, the variation in the thickness of the yoke plate is absorbed, and components such as the yoke set in the molding die K are fixed so as not to rattle. In other words, according to this configuration, the dimensions of the mold where the three parts of the yoke 5, the elastic inclusion 12 and the yoke 6 overlap each other have the minimum thickness of the yokes 5 and 6 for the elastic body. The thickness is set to be substantially equal to the size obtained by adding the thickness of the object 12, and when the thickness of the stacked components becomes larger than the mold size due to the variation in the thickness of the yoke plate, the elastic body 12 Are compressed and deformed to absorb variations in plate thickness. After completion of the mold clamping, a molten resin is injected into the molding die K, and the yokes 4 and 5, the elastic inclusions 12, and the yokes 6 and 7 are integrally fixedly molded with the molding resin, respectively. A yoke is made. Thus, in the second embodiment of the present invention,
The elastic inclusion 12 interposed between the yoke 5 and the yoke 6 acts as a cushion material so that even if the yoke plate thickness slightly varies, the variation is absorbed and the nonmagnetic inclusion 12 is used. Each phase is magnetically separated by the non-magnetic layer. Therefore, according to the second embodiment, the yoke 5 opposed to the rear surface is irrespective of the variation in the thickness of the yoke plate.
The yoke 6 and the yoke 6 are supported by an elastic nonmagnetic inclusion 12 so as not to be in close contact with each other. A gap G (magnetic gap) is formed between the yoke 5 and the yoke 6, and the yoke 5 and the yoke 6 are fixed to the stator. The positional relationship can be set with high accuracy irrespective of the variation in the thickness of the yoke plate, and the characteristics of the stepping motor (angle accuracy, noise due to vibration, torque unevenness, etc.) are significantly improved as in the case of the first embodiment described above. be able to. The formation of the nonmagnetic layer by the inclusions 12 is not limited to the case of the mold yoke, but can be naturally applied to a stepping motor which is assembled by sequentially interposing individual parts in the outer cylinder portion 8. FIG. 8 shows an embodiment of the present invention. FIG. 8 is similar to the case of the above-mentioned mold yoke, and is a non-magnetic inclusion (for example, a resin material or a paper material having irregularities) between the yokes 5 and 6 which are opposed to each other. 8A is an example in which a non-magnetic layer 12 is formed by interposing a non-magnetic rigid body such as metal or ceramic with a resin coating or sandwich.
(b) is a pancake type stepping motor, FIG.
(c) is a cup type stepping motor. In any case, a high-performance stepping motor is realized. FIG. 3 is a view showing a third embodiment of the method of manufacturing a mold yoke according to the present invention. As in the first and second embodiments, a longitudinal section of a molding die loaded with components is shown. FIG. In FIG. 3, 4, 5, 6, and 7 are yokes.
K1 is a first step for supporting the yoke 5 provided on the key of the molding die K, and K2 is a second step for supporting the yoke 6 facing the back of the yoke 5. .
As shown, in the present embodiment, the first stepped portion K
The step T between the first and second steps K2 is set to be slightly larger than the maximum thickness of the yoke 5, and the yokes 5 and 6 are separately supported by the stepped keys. A gap G (magnetic gap) is formed between the gaps. In the method of manufacturing a mold yoke according to the present embodiment, first, the yoke 4 is set in the molding die K, and then the yoke 5 is connected to the first step K1 of the stepped key by the flange b. The yoke 6 is set so as to be supported, and further, the yoke 6 is set so that the flange b is supported by the second step K2, and finally the yoke 7 is set. At this time, a gap G is formed between the yoke 5 and the yoke 6 due to the difference between the step T and the yoke plate thickness. After completion of the mold clamping, a molten resin is injected into the molding die K, and the plurality of yokes 4, 5, 6, 7 are integrally fixedly molded with the molding resin. When the molten resin is injected, the gap G between the yoke 5 and the yoke 6 is the same as in the first embodiment.
A non-magnetic layer may be formed of a mold resin by pouring a resin into the resin, or may be present in a gaseous state as it is. As described above, in the third embodiment of the present invention,
Since the yoke 5 and the yoke 6 facing each other on the rear side are separately supported by the stepped keys, even if the thickness of the yoke 5 varies in the range of the maximum thickness, a gap is provided between the yoke 5 and the yoke 6. G (magnetic gap) is formed, and the displacement of the yokes 5 and 6 with respect to the stator is stopped within the range of one sheet with a thickness variation of each yoke. In addition, according to this structure, a gap G is formed between the yoke 5 and the yoke 6 in which the projections 13 and the inclusions 12 do not exist at all, as in the above-described embodiment.
The magnetic shielding effect between the phases is more complete. As described above, in the present embodiment, the mold yoke of the two-phase stepping motor has been described. However, the present invention is not limited to this, and is naturally applicable to stepping motors other than the two-phase structure. Further, in the present embodiment, the case where the mold yoke is constituted by using four types of yokes 4, 5, 6, and 7 having different shapes has been described, but the yokes 4 and 7 and the yokes 5 and 6 have the same shape. Or yoke 4, 5, 6,
7 may have the same shape. Further, in this embodiment, the parts set in the molding die K have been described as only the yokes 4, 5, 6, and 7. However, as shown in FIGS. Of course, components other than 5, 6, 7 such as the bearing 14, the yokes 4, 5 and the spacer 15 for maintaining the interval between the yokes 6, 7, etc. may be combined together and integrally fixedly formed. . In the above-mentioned molding, as a resin material, for example, a thermoplastic resin such as liquid crystal polymer (LCP), polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), polyacetal (POM), polyethylene terephthalate (PET), etc. Known resin materials such as thermosetting resins such as phenolic resins and epoxy resins can all be used. Next, a gap is formed by interposing a 0.8 mm thick spacer between the yoke 5 and the yoke 6 and a conventional yoke having no non-magnetic layer between the yoke 5 and the yoke 6 facing the back. A stepping motor having a two-phase structure using the formed yoke of the present invention was manufactured, and the respective characteristics (angle error for each step) are shown in FIGS. 9 and 10. FIG. 9 shows the case of one-phase excitation drive. FIG. 9A shows a conventional product, and FIG. 9B shows a product of the present invention. FIG. 10 shows a case of two-phase excitation drive, and FIG.
0 (a) is a conventional product, and FIG. 10 (b) is a product of the present invention. In addition,
CW shown by a solid line in the figure is a case where the stepping motor is rotated forward, and CCW shown by a broken line is a case where the stepping motor is rotated reversely. As is apparent from FIGS. 9 and 10,
Compared to conventional products, the stepping motor of the present invention
In either case of the phase excitation drive or the two-phase excitation drive, the angular error for each step is remarkably improved. Although the characteristics of the stepping motor are not shown, even in the case of the 1-2-phase excitation drive, the angular error is naturally remarkably improved in the same manner as in the above-described one-phase excitation drive or two-phase excitation drive. It is. As described above, according to the first aspect of the present invention, in the method of manufacturing a mold yoke,
A first step having a step in the molding die that is greater than the thickness of the yoke
And a second step portion, and these steps constitute each phase.
Support the yokes facing each other separately.
The yokes are sequentially loaded into a molding die and
To create a gap between the yokes
When the thickness of the yoke varies within the range of the maximum thickness,
The position accuracy of the yoke with respect to the stator
It can be stopped within the range of one sheet with a thick rose
You. In addition, according to this configuration, it is formed between the yokes.
The voids are voids in which the above-mentioned protrusions and inclusions do not exist at all.
Since it is a gas layer (magnetic gap layer),
The resin is poured into the gap, or the gap is
Leakage between phases, either in phase or in any case
The magnetic flux shielding effect is more complete. Also, this configuration
Then, is the above-mentioned protrusion or inclusions unnecessary?
Therefore, the processing of the yoke and the loading of the parts are simplified, and the number of steps can be reduced . The following is an example of the above.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view showing a first embodiment of a method for manufacturing a mold yoke for a stepping motor according to the present invention, and is a longitudinal sectional view of a molding die loaded with components. FIG. 2 is a view showing a second embodiment of the method for manufacturing a mold yoke for a stepping motor, and is a longitudinal sectional view of a molding die loaded with components; FIG. 3 is a view showing a third embodiment of the method for manufacturing a mold yoke for a stepping motor, and is a longitudinal sectional view of a molding die loaded with components; FIG. 4 is a view showing a third embodiment of the method for manufacturing a mold yoke for a stepping motor, and is a longitudinal sectional view of a molding die different from FIG. 3 in which components are loaded. FIG. 5 is a view showing a step of loading components into a molding die. FIGS. 6A and 6B are longitudinal sectional views of a stepping motor showing a state of a yoke set in an outer cylinder portion, wherein FIG. 6A shows a curling type, FIG. 6B shows a pancake type, and FIG. FIG. 7 is a view showing a state of a yoke set on an outer cylinder portion;
FIGS. 4A and 4B are longitudinal sectional views of another stepping motor, in which FIG. 4A shows a curling type, FIG. 4B shows a pancake type, and FIG. FIG. 8 is a view showing a state of a yoke set on the outer cylinder part.
FIGS. 4A and 4B are longitudinal sectional views of another stepping motor, in which FIG. 4A shows a curling type, FIG. 4B shows a pancake type, and FIG. 9A and 9B are diagrams showing characteristics of a stepping motor in the case of one-phase excitation driving, where FIG. 9A is a conventional product and FIG. 9B is a product of the present invention. 10A and 10B are diagrams showing characteristics of a stepping motor in the case of two-phase excitation driving, where FIG. 10A is a conventional product and FIG. 10B is a product of the present invention. FIG. 11 is a sectional perspective view showing a configuration of a stepping motor. FIG. 12 is a perspective view showing one embodiment of a yoke. FIG. 13 is a longitudinal sectional view of a molding die of a conventional stepping motor mold yoke loaded with components. FIG. 14 is a longitudinal sectional view of a conventional stepping motor showing a state of a yoke set in an outer cylinder portion. [Description of Signs] 1 Rotor 2 Permanent magnets 4, 5, 6, 7 Yoke 8 Outer cylinder part 10, 11 Magnetic excitation coil 12 Nonmagnetic layer (inclusion) 13, 16 Projection a Magnetic pole tooth b Flange G Gap K Molding die K1 First step K2 Second step T Step

Continuation of front page (56) References JP-A-5-219714 (JP, A) JP-A-8-317623 (JP, A) JP-A-8-65994 (JP, A) JP-A-8-289527 (JP, A) , A) Fully open 1987-161578 (JP, U) Fully open 57-93088 (JP, U) Fully open 4-4-39078 (JP, U) Fully open 1986-113580 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) H02K 37/00

Claims (1)

(57) [Claims 1] A comb-shaped mold (K) and a comb-shaped flange (b).
A plurality of yokes (4, 5, 6, 7) provided with pole teeth (a)
After loading while combining sequentially, with the mold resin
Mold yo for stepping motor that is integrally fixed and formed
In the method for manufacturing a yoke (5), the inner wall of the molding die (K) has a thickness equal to or less than the thickness of the yoke (5).
First step (K1) with upper step (T) and second step
A portion (K2), which is located inside the plurality of yokes (4, 5, 6, 7);
Of the yoke (5) and the yoke (6) opposed to the back,
A yoke (5) is supported by the first step (K1).
At the same time, the yoke (6) is connected to the second step (K2).
The plurality of yokes (4, 5, 6,
7) are sequentially loaded into the molding die (K) and are opposed to the rear surface.
Forming a gap (G) between the yoke (5) and the yoke (6)
And, then, the multi by injecting molten resin the in the molding die (K)
Number of yokes (4, 5, 6, 7)
Body fixedly molded, between yoke (5) and yoke (6)
The non-magnetic layer (1
2) Formed for stepping motor
Manufacturing method of mold yoke.