JPH09172748A - Sealed type stator and rotor for small-sized motor, and these manufacture, and iron core molded with insulator inserted - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture sealed type stator and rotor by injection molding without damaging the winding. SOLUTION: An iron core 1 is inserted in a mold, and an insulator made of thermoplastic or thermosetting insulating synthetic resin is undermolded 8 to the iron core 1 so as to cover the surface of the iron core 1, and then the winding 10 is laid thereon to make a stator 11 of a rotor. Next, the gate position of a mold is provided in the position where the injected resin does not hit directly on the winding 10 of the stator 11 or the rotor, and the thermoplastic resin is overmolded 12 to the stator 11 or the rotor by injection molding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an iron core such as a motor armature, a magnetic field, a transformer, an electromagnet, and a reactor. It is particularly suitable for an armature core of a thin-walled molding motor such as a spindle motor.

Further, a stator or rotor using the above-mentioned iron core, or a stator or rotor of another type is overmolded by injection molding to cover the windings, and in particular, a hard disk device or the like. It is suitable for small precision motors that require a clean environment.

[0003]

2. Description of the Related Art In recent years, various small and thin motors have been used in various fields, and along with this demand for smaller and thinner armature cores and insulators, the manufacturing process is simplified. There is an increasing demand for improvement in reliability and reliability.

[0004] In particular, there is an increasing demand for a smaller and thinner motor as a market requirement. If insulation with the iron core can be maintained, the thinner the insulator, the larger the winding dose, and the higher the starting force and the lower the motor's power. Performance such as power is also improved. In addition, there is an operational effect such that heat generated in the motor is easily dissipated as the insulator is thinner. Furthermore,
In a household electric motor, by encapsulating with a flame-retardant resin, it is possible to prevent the occurrence of a fire from the motor, which is an effective means in the PL method.

On the other hand, in the case of a spindle motor used in a hard disk drive, in addition to the above-described miniaturization and thinning, if minute dust or the like adheres to a magnetic head or a hard disk,
Since it causes noise and head crash, it is necessary to prevent dust and gas from being generated from the motor.

[0006] Particles, organic substances, ionic substances, and gases are mainly generated from the motor. In particular, it is necessary to prevent scattering of contaminants caused by rubbing between the windings of the stator and the rotor, which is also important for improving the durability of the hard disk drive.
Also, in order to improve the performance of the hard disk drive, it is necessary to prevent vibration and noise generated by the current pulse.

[0007]

By the way, in order to manufacture an armature core in the related art, a plurality of thin steel plates punched into a shape are crimped to form a laminated core, which is rustproofed and then subjected to an insulation treatment by painting. Was there. Then, after bonding the winding guide to this, winding was performed.

However, in order to stack the thin steel sheets that have been punched, it is inevitable that the outer periphery, the slot, and the like, where the laminated surface is exposed, will not be a perfect plane, and that irregularities will occur. A major problem with inserts is that there is variation in the thickness of the laminated core. For this reason, insert molding requires a large amount of cost, such as classification by the thickness of the laminate or operation of the adjusting core in the mold. In addition, in the conventional stack thickness classification method of the insert method and the in-mold adjustment moving core method, burrs are generated in both of them, so that it is necessary to remove burrs at a large cost.

In order to insulate such a concavo-convex surface, it was necessary to apply a coating with a thickness of about 50 to 80 μm. Coating requires a shot blasting or barreling process for deburring as a pre-process, which increases the cost and also tends to cause pinholes etc., resulting in poor insulation, resulting in peeling of the edge part and therefore yield. It was bad. In addition, it is necessary to bond the winding guide after painting, which complicates the manufacturing process.

In some cases, an insulator molded in advance from a synthetic resin is attached to a laminated iron core, but an insulator of a normal thin molded product has a wall thickness of 0.
The limit is about 2 mm, and in order to prevent the insulator from deforming or falling off, special bonding methods and insulators are required, skill is required for work, and there is no wall thickness. The rigidity of synthetic resin products having a size of 2 mm or less was insufficient and they were often deformed, so that they could not be assembled together with the iron core.

In order to improve resistance and inductance, insulation by an insulator is better than painting.

That is, in order to solve the above problems,
It suffices if it is possible to manufacture an iron core that has been subjected to an insulation treatment by a simple manufacturing process while preventing the generation of defective products, and at the same time mold an insulator, and improve the resistance value and the inductance value.

On the other hand, in order to prevent the scattering of contaminants caused by the rubbing of the windings of the stator and the rotor and the vibration and noise generated by the current pulse, the windings are made of synthetic resin or the like. It must be hermetically sealed so that the windings are not directly exposed to the outside.

The winding of the motor used in the hard disk drive has a diameter of about 0.12 mm, and the diameter is about 0.15 mm including the thickness of the covering material. The heat resistant temperature of the covering material is about 150 ° C. That is, in order to miniaturize the motor, the winding is thin and the covering material is thin, and a material that is easily damaged by heat or pressure is used.

Although sealing has been performed for such a purpose from the past, the conventional sealing is a bulk molding compound (BMC) using a thermosetting resin.
It is done by law. According to the BMC method, since it is carried out at a low temperature and a low pressure, the productivity is low and the molding temperature is 120.
Although the temperature is not so high at about ℃, the winding is exposed to this temperature for a long time, resulting in damage to the coating material of the winding such as peeling.

Therefore, in order to improve the productivity, a method of encapsulating and molding by using an injection molding method using a thermoplastic resin is conceivable. However, when injection molding is performed by a usual method, the winding layer is formed by injection pressure. If the die gate position is in a position where the coil is disturbed and the winding is directly hit, the winding is directly damaged.

On the other hand, the injection molding temperature of the thermoplastic resin is generally about 300 ° C., and the heat resistant temperature of the winding is about 150 ° C. Therefore, in general, if the winding is damaged during molding. Although conceivable, various experiments conducted by the inventor have revealed that the winding can withstand the injection molding temperature depending on the molding method.

That is, in order to perform the sealing molding by using the thermoplastic resin by the injection molding method, it is necessary to provide the gate position of the mold at a position where the winding is not directly hit. And, more desirably, injection molding should be performed at a lower pressure than usual to prevent the winding layers from being disturbed.

And a pressure lower than usual (20% of usual)
In order to perform molding at a pressure of -60%), it is basically effective to use a high fluidity resin, although it depends on the type of resin used.

[0020]

In order to solve the above-mentioned problems, the sealed stator and rotor for a small motor according to the present invention has a structure in which an insulator made of an insulating synthetic resin is insert-molded on an iron core. The stator or rotor having the above-mentioned structure is coated with a thermoplastic resin by injection molding (Claim 1). Alternatively, a commonly wound stator or rotor is coated with a high-fluidity thermoplastic resin by injection molding (claim 2), and if necessary, the injection-molded thermoplastic resin is used as a high-fluidity resin. (Claim 3).

Further, in order to solve the above-mentioned problems, the method for manufacturing a sealed stator and rotor for a small motor according to the present invention inserts an iron core into a mold, and uses a thermoplastic or thermal material so as to cover the surface of the iron core. The iron core is undermolded with an insulator made of a curable insulating synthetic resin, and the winding is wound to form a stator or rotor.Then, the resin injected onto the winding of this stator or rotor does not directly hit the metal. A mold gate position is provided, and a thermoplastic resin having high fluidity is overmolded on the stator or the rotor by injection molding to cover the stator or rotor (claim 4). Alternatively, it is manufactured in the same manner by using a commonly wound stator or rotor (Claim 5). A high fluidity resin is used as the thermoplastic resin which is overmolded by injection molding in some cases (claim 6).

The injection pressure at the time of overmolding is set to a normal pressure of 20% to 60% (claim 7). As a result of the experiment conducted by the inventor, the best result was obtained when the pressure was 45% to 50% of the normal injection pressure.

On the other hand, in order to solve the above problems, the iron core insert-molded with the insulator according to the present invention is
An insulator made of an insulating synthetic resin for covering the surface of the iron core is insert-molded on the iron core (claim 8). The iron core can be used for the stator and rotor, and is also suitable for other uses.

For use as an armature iron core, at least the end face and the slot of the iron core are covered (Claim 9), or the entire circumference except for the inner diameter or outer diameter side face which becomes the rotor insertion portion (Claim 10). ) Or all around (claim 1
An insulator made of an insulating synthetic resin is insert-molded on the iron core so as to cover 1).

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an embodiment of a sealed type stator and rotor for a small motor according to the present invention, a method for manufacturing them, and an iron core in which an insulator is insert-molded will be described. First, an iron core formed by insert molding an insulator will be described as a first embodiment, and then a manufacturing method of a sealed stator using the iron core will be described as a second embodiment.

[Embodiment 1] First, an embodiment of an iron core in which an insulator is insert-molded will be described for an armature iron core for a spindle motor used in a hard disk drive with reference to FIGS. Reference numeral 1 denotes a laminated iron core formed by caulking a plurality of thin steel plates. 2 is an insulator insert-molded into this laminated iron core.

The insulator 2 is the laminated iron core 1
It is formed so as to cover both end faces 3, the slot 4 and the outer periphery 5. That is, the insulator 2 made of a thin insulating synthetic resin is insert-molded so as to cover the entire circumference except for the inner diameter side surface 6 which becomes the rotor insertion portion. Reference numeral 7 denotes a winding guide formed on the end face 3 of the insulator 2. It should be noted that the insulator 2 may have a wall thickness of 0.2 mm or less to cover the entire circumference without removing the inner diameter side surface 6. Also, depending on the method of use, the entire circumference except the outer diameter side surface may be covered.

Alternatively, as shown in FIG. 5, the insulator 2 is formed so as to cover both end surfaces 3 of the laminated iron core 1 and the slots 4, and the winding guide 7 is formed on the end surface 3 of the insulator 2. This is an epoch-making product in which a winding guide is simultaneously molded with a thin molding insert (for example, a wall thickness of 0.2 mm or less). Note that the shape of the winding guide 7 is not limited to the illustrated inverted L-shape, but may be vertical or diagonally I-shaped.

The synthetic resin for molding the insulator 2 may be either a thermoplastic synthetic resin or a thermosetting synthetic resin as long as it is an insulating synthetic resin. For example, 66 nylon, PBT resin, LCP resin, PPS resin, etc. Can be used.

Although the above embodiment has described the armature core of the thin-walled molding motor, the core formed by insert-molding the insulator of the present invention is not limited to the above-mentioned embodiment, and may be, for example, a motor field or a transformer. It can also be used for iron cores such as electromagnets and reactors. Further, it is needless to say that the winding guide 7 may be provided in the above-described embodiment depending on the application and may not be necessarily provided.

In the above embodiment, the insulator having a thickness of 0.2 mm or less has been described.
Although the present invention is basically not limited in terms of thickness, it is effective when the thickness is 0.3 mm or less as compared with the molded product, and when the molded product is difficult to manufacture at a thickness of 0.2 mm or less. Will be particularly effective.

[Embodiment 2] Next, a method for manufacturing a sealed stator using the above armature core will be described. In addition, in the following description, the insulator 2 may be referred to as an under mold 8.

First, the teeth 9 of the laminated core 1 having the undermold 8 are wound with windings 10 to form a stator 11. For this, the winding 10 may be formed by a usual method.

A gate position of a mold is provided at a position where the injected resin does not directly hit the winding 10 of the stator 11, and a highly fluid thermoplastic resin is overmolded 12 on the stator by injection molding. The winding 10 is covered. As a result, the winding 10 is not directly exposed to the outside,
The encapsulated stator of the present invention in the state of being overmolded 12 with resin is manufactured. In addition, if the gate position is adjusted as described later, the high fluidity resin does not necessarily have to be used.

By setting the gate position so as not to hit the winding 10 directly, it is possible to prevent the winding 10 from being damaged by the injection pressure. The actual gate position is, for example, slot 4
Among them, more specifically, between the teeth 9 which are adjacent to each other and are processed by the winding 10 of the stator 11. Further, it is preferable that the number of gates is large in order to complete the injection molding in a short time, but this may be appropriately selected depending on the size of the stator and the number of poles.

As the high fluidity thermoplastic resin, for example, liquid crystal polymer (LCP resin), PPS resin, PBT resin, 66 nylon or the like can be used. When these resins are used, the molding temperature is around 300 ° C,
By sealing-molding using such a resin having a high heat resistant temperature, a motor having excellent durability can be obtained.

Although the injection pressure differs depending on the resin material used, when using the resin as described above, if the pressure is set to 20% to 60% of the normal pressure, the layer disorder of the winding 10 can be prevented. The best results are easily obtained when the pressure is about 45% to 50%. By using a high fluidity resin, the injection pressure can be lowered, and injection molding can be performed in a short time.

Polyacetal resin (POM resin)
Even if the resin is not a high-fluidity resin, by appropriately setting the gate position, it can be molded at a temperature of about 120 ° C. to 130 ° C. under normal injection pressure without damaging the winding.

The stator to be used is not limited to the iron core insert-molded with the insulator according to the present invention, but may be the iron core manufactured by another conventional method. By using the iron core having the undermold 8 according to the present invention, it is possible to manufacture a spindle motor which is small in size and highly accurate for a hard disk device, and which is clean and has excellent durability. Although the above embodiment describes the stator, the rotor can be manufactured by the same method.

[0040]

As described above, according to the sealed stator and rotor for a small motor of the present invention, a stator or rotor having an iron core wound by insert molding of an insulator made of an insulating synthetic resin is used. Since the thermoplastic resin is coated by injection molding, contaminants can be prevented from flowing out from the winding wire while the motor is operating, and vibration and noise generated by the current pulse can be suppressed. Further, in a motor for home electric appliances, by encapsulating with a flame-retardant resin, a fire from the motor can be prevented, which is an effective means in the PL method.

Further, according to the method of manufacturing the sealed stator and rotor for the small motor of the present invention, the core is inserted into the mold and the thermoplastic or thermosetting insulating composite is formed so as to cover the surface of the core. After the resin insulator is undermolded on the iron core to cover it, winding is done to make a stator or rotor, and then the gate position of the mold is provided at a position where the resin injected to the stator or rotor winding does not directly hit Since the thermoplastic resin is overmolded and coated on the stator or rotor by injection molding, it is possible to easily manufacture a sealed stator or rotor by injection molding without damaging the winding. it can.

On the other hand, according to the iron core insert-molded with the insulator of the present invention, the insulator of the insulating synthetic resin coating the surface of the iron core is insert-molded on the iron core, so that the insulation treatment can be completed and the resistance value and This has the effect of improving the inductance value and simplifying the manufacturing method. Moreover, by using it as the iron core of the stator or rotor of the present invention,
It is possible to manufacture a compact and high-performance spindle motor.

[Brief description of the drawings]

FIG. 1 is a plan view of an iron core insert-molded with the insulator of the present invention.

FIG. 2 is a front view of an iron core insert-molded with the insulator of the present invention (the winding guide is partially omitted).

FIG. 3 is an end view taken along line AA of FIG. 1;

FIG. 4 is an end view taken along the line BB of FIG.

FIG. 5 is a front view showing another example of an iron core insert-molded with the insulator of the present invention (the winding guide is partially omitted).

FIG. 6 is a plan view of a sealed stator according to the present invention.

7 is an enlarged end view taken along line CC of FIG. 6;

[Explanation of symbols]

 1 laminated iron core 2 insulator 3 end face 4 slot 5 outer circumference 6 inner diameter side face 7 winding guide 8 undermold 9 teeth 10 winding 11 stator

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[Procedure amendment]

[Submission date] September 17, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Explanation of sign

[Correction method] Change

[Correction contents]

[Explanation of symbols] 1 laminated iron core 2 insulator 3 end face 4 slot 5 outer circumference 6 inner diameter side face 7 winding guide 8 undermold 9 teeth 10 winding 11 stator 12 overmold

Claims (13)

[Claims] Claim: What is claimed is: 1. A small motor encapsulation characterized in that a stator or rotor having an iron core formed by insert molding of an insulating synthetic resin insulator is wound with a thermoplastic resin by injection molding. Type stator and rotor. 2. A sealed stator and rotor for a small motor, characterized in that a stator or rotor having a winding on an iron core is coated with a thermoplastic resin by injection molding. 3. The sealed stator and rotor for a small motor according to claim 1, wherein the injection-molded thermoplastic resin is a highly fluid resin. 4. An iron core is inserted into a mold, and an insulator made of a thermoplastic or thermosetting insulating synthetic resin is undermolded on the iron core so as to cover the surface of the iron core. A stator or rotor is provided, and then a gate position of a mold is provided at a position where the injected resin does not directly contact the winding of the stator or rotor, and the thermoplastic resin is overmolded and coated on the stator or rotor by injection molding. A method for manufacturing a sealed stator and rotor for a small motor, characterized by the above. 5. A gate position of a mold is provided on a stator or a rotor having a winding on an iron core, at a position where the resin injected onto the winding of the stator or rotor does not directly contact with the stator.
A method for producing a sealed stator and rotor for a small motor, characterized in that a thermoplastic resin is overmolded onto the stator or rotor by injection molding to cover the stator or rotor. 6. The method for producing a sealed stator and rotor for a small motor according to claim 4, wherein the thermoplastic resin overmolded by injection molding is a highly fluid resin. 7. An injection pressure at the time of overmolding is set to a normal pressure of 20% to 60%, and the sealed stator and rotor for a small motor according to claim 4, 5 or 6. Production method. 8. An iron core insert-molded with an insulator, characterized in that an insulator made of an insulating synthetic resin for covering the surface of the iron core is insert-molded on the iron core. 9. An iron core insert-molded with an insulator, characterized in that an insulator made of an insulating synthetic resin is insert-molded so as to cover at least the end face and the slot of the iron core. 10. An iron core insert-molded with an insulator, characterized in that an insulator made of an insulating synthetic resin is insert-molded so as to cover the entire circumference excluding the inner diameter or outer diameter side surface which becomes the rotor insertion portion. 11. An iron core insert-molded with an insulator, characterized in that an insulator made of insulating synthetic resin having a thickness of 0.2 mm or less is insert-molded so as to cover the entire circumference. 12. An iron core obtained by insert-molding the insulator according to claim 8, 9, 10 or 11, wherein the iron core is a laminated armature core for a spindle motor. 13. An iron core insert-molded with the insulator according to claim 8, claim 9, claim 10 or claim 11, wherein the winding guide is integrally molded with the insulator.