JPH036733B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a coreless armature, in which at least the armature winding portion is made into an integrally rigid body by polymerizing and curing a thermosetting resin.

Generally, the armature winding is made into a rigid body by wrapping a predetermined number of electric wires around it and fixing it together with the supporting core using a binder such as varnish. However, in the case of an armature winding without a supporting core, such as a coreless armature, the armature winding itself must be made integrally rigid by some method. In particular, in the case of armature windings as relatively large coreless armatures ranging from several watts to several hundred watts, the properties required for making them into a single rigid body are sophisticated, such as strength at high temperatures,
An integrally rigid body that can meet dimensional safety, thermal shock resistance, electrical insulation, and long-term heat deterioration resistance is required. Therefore, a coreless armature has been put into practical use in which transfer molding is applied to at least the armature winding portion of the coreless armature using a thermosetting resin molding material that usually contains 50% or more of an inorganic filler.

The transfer molding used for such iron core armatures is
First, the armature winding is placed in a mold, and a thermosetting resin is injected by applying pressure from outside the mold to form an integral rigid body.

In addition, the relatively large ironless core armatures, ranging from a few watts to several hundred watts, are often used as motors to perform incremental operations by taking advantage of their quick response. magnetic disk, facsimile,
They are often used in fields such as automatic welding machines, industrial robots, and machine tools, but as the performance and precision of these devices has increased, motors with even higher control responsiveness, i.e., low inertia and ironless motors, are being used. The appearance of an armature was desired.

The present invention has been made in view of the above-mentioned needs, and relates to a manufacturing method for the purpose of lowering the inertia of a coreless armature in which at least the armature winding portion is made into an integral rigid body by polymerizing and curing a thermosetting resin. It is.

That is, in a method for manufacturing a coreless armature in which a thermosetting resin is polymerized and hardened in a mold to make at least the armature winding part an integral rigid body, at least the basic resin is polymerized by heating. A material to be cured, a foaming agent to be foamed by heating,
Using a thermosetting resin containing a plurality of minute hollow spheres with minute diameters made of inorganic material, this thermosetting resin is placed or filled on the commutator side winding terminal part of the armature winding in the mold. At the same time, some of the micro hollow spheres are destroyed by the pressure during mold clamping, and by heating after mold clamping, the foaming agent included in the thermosetting resin is expanded, and this expansion pressure causes the foaming agent to expand. The thermosetting resin is then filled into a mold including the end portion of the coil on the side opposite to the commutator, and at the same time, the thermosetting resin is integrally made into a rigid body by polymerization and curing.

The present invention will be explained in more detail below.

The coreless armature that is the object of the present invention is used as a motor ranging from several watts to several hundred watts, and if it is a wire-wound type coreless armature, the armature winding is flat. It may also be cup-shaped. Furthermore, even if the armature winding is an unshaped armature winding that has not been shaped into a predetermined shape,
There is no problem even if it is a shaped armature winding.

Further, in the present invention, the thermosetting resin may be solid at room temperature or in the form of a putty, but a putty-like resin is preferable since the minute hollow spheres are less likely to be broken during the production of the thermosetting resin. Further, it is preferable to use transfer or injection molding for solid materials, and compression molding for putty materials.

The thermosetting resin used in the present invention is a basic resin,
It is a compound that polymerizes and hardens this by heating, or a polymerization initiator, a foaming agent, micro hollow spheres, and additives added as necessary. It is also possible to use a woven fabric or non-woven fabric made of organic or inorganic material on the surface, or a prepreg body made of such as a base material, as appropriate, and arrange a prepreg cured layer on one or both surfaces of the armature winding.

The thermosetting resin used in the present invention will be explained below.

The basic resin includes unsaturated polyester, diallyl phthalate, urethane, phenol, epoxy, etc., and among them, unsaturated polyester resin is preferred. The unsaturated polyester resin used in the present invention refers to α,β unsaturated carboxylic acids or these, saturated dicarboxylic acids, organic acids including saturated and unsaturated monocarboxylic acids, and alcohols, that is, glycols,
An unsaturated polyester obtained by esterification reaction with polyhydric alcohols and monohydric alcohols is dissolved in a crosslinking monomer that can be polymerized with the unsaturated polyester, and usually contains a small amount of polymerization inhibitor, and if desired. Examples include those containing polystyrene, polyethylene, polymethyl methacrylate and copolymers, and polyvinyl chloride polycaprolactone saturated polyesters as low shrinkage agents.

In the case of the above basic resin, an organic peroxide, such as benzoyl peroxide, as a polymerization initiator,
Examples include τ-butyl perbenzoate, and metal salts such as cobalt naphthenate and cobalt octoate, and amines such as triethanolamine and diethylaniline are optionally used as accelerators.

Examples of blowing agents include substances that generate gas when heated, such as dinitrolipentamethylenetetramine, azodicarbonamide, toluenesulfonyl hydrazide, azoisobutylnitrile, or acrylonitrile-vinylidene chloride copolymer, acrylonitrile-MMA copolymer. , polystyrene, polyα-methylstyrene, polyisobutylene, etc., which generate gas when heated, or propane, butane, pentane, hexaneheptane, dichloropentadiene, petroleum ether, and other fine capsule materials are not dissolved. Those impregnated with aliphatic and cycloaliphatic hydrocarbons as blowing agents are used.

Microscopic hollow spheres include borosilicate glass, insoluble glass, silicates, aluminosilicate, shirasu,
Hollow spheres made of inorganic materials such as silica sand, obsidian, and alumina and having minute diameters are used.

In addition, additives added as necessary include granular fillers such as calcium carbonate, hydrated alumina, and silica, fiber fillers such as glass and vinylon, and mold release agents such as calcium stearate and zinc stearate.
Coloring agents such as titanium oxide and phthalocyan blue are used as appropriate.

The present invention uses a thermosetting resin composed of the above components, that is, a thermosetting resin blended with a foaming agent, micro hollow spheres, and additives added as necessary, to the commutator side winding end portion of the armature winding. It is characterized by being filled with. In the case of a putty-like thermosetting resin, it is placed directly on the end portion of the armature winding on the commutator side, and then a preheated mold is clamped. In addition, in the case of a thermosetting resin that is solid at room temperature, after plasticizing the resin in advance, it is placed on the terminal part of the armature winding on the commutator side (with the mold open) or filled (with the mold clamped). state).

Pressure is applied to the thermosetting resin placed on the commutator side winding end of the armature winding as the mold is clamped, and the thermosetting resin is filled from the commutator side winding end of the armature winding. At the same time, the polymerization and hardening of the resin and the foaming of the foaming agent are started by heat conduction from the mold, and the mold including the end portion of the winding on the side opposite to the commutator of the armature winding is caused by the expansion pressure of the foaming agent. filled within.

On the other hand, due to the pressure applied to the thermosetting resin during mold clamping, some of the microscopic hollow spheres are destroyed and most of them remain as solid fillers at the end of the winding on the commutator side of the armature winding. The hollow sphere moves according to the flow of the resin to a portion including the winding end portion on the side opposite to the commutator.

When the mold clamping is completed, the pressure of the thermosetting resin at the time of clamping is removed, and the flow of the thermosetting resin toward the end of the armature winding opposite to the commutator is restricted. The thermosetting resin gradually fills each part of the armature winding, and this filling pressure is due to the foaming pressure of the foaming agent inside the thermosetting resin. In other words, the closer the armature winding is to the end of the winding on the side opposite to the commutator, the more intense foaming inevitably occurs, and the pores generated in the thermosetting resin or the microcapsules containing the foaming agent are destroyed, resulting in partial foaming. The pores become more likely to become continuous and may grow into even larger voids, which may reduce the mechanical strength. However, the micro hollow spheres in the thermosetting resin act as partition walls between the pores, preventing uneven partial open pore formation, and making it possible to maintain uniform, minute, independent pores.

In the manufacturing method of the present invention, after completely filling the mold with thermosetting resin as described above, the polymerization and curing of the resin that was progressing at the same time is completed, and the armature winding is made into an integrally rigid body. . In the iron-core armature obtained by this manufacturing method, the thermosetting resin cured material at the commutator side winding end portion of the armature winding has a solid filler made of some broken microscopic hollow spheres. In addition, this part has a high degree of resin filling and a low foaming degree of the foaming agent, so it has a high density.
In other words, it is a cured product with high strength. The thermosetting resin in the direction opposite to the commutator side winding end of the armature winding is
Along this direction, the degree of expansion of the resin due to the foaming pressure of the foaming agent gradually increases, and since the micro hollow spheres serve as partition walls, the cured product has a low density with uniform closed pores, that is, it is lightweight and has little variation in strength. It has become.

Furthermore, it is desirable that the above-mentioned iron-core armature has little noise and vibration as a motor, and for this purpose, ribs made of a cured thermosetting resin are provided on the outer periphery of the iron-free armature, that is, on the end portion of the armature winding on the side opposite to the commutator. established,
This is often cut to correct the weight balance of the entire coreless armature.
In this work, if the iron-free electrical armature of the present invention has a structure in which micro hollow spheres act as partition walls and have minute closed pores that prevent the formation of open pores due to foaming of the foaming agent, there will be no problem in the work efficiency. It doesn't hurt. However, if only micro hollow spheres are not included, the portion where the foaming agent is most vigorously foamed will have more open pores and coarse voids will be formed in some areas, so the weight balance of the ironless armature will be balanced. This makes the task of doing so extremely difficult.

Furthermore, if the thermosetting resin does not contain minute hollow spheres as described above, the foaming agent may be foamed in the direction of the outermost circumference of the coreless armature, that is, in the direction of the ends of the windings on the side opposite to the commutator of the armature windings. Due to the reasons mentioned above, it is necessary to prevent the formation of continuous pores by increasing the amount of thermosetting resin required and increasing the pressure inside the mold to reduce the degree of expansion. Since the degree of foaming of the thermosetting resin in the direction of the outer circumference of the armature decreases, the moment of inertia of the coreless armature increases.

Examples are shown below.

Example: An insulated wire with a self-bonding layer with a wire diameter of 0.25 mm was
We prepared an armature winding group consisting of a commutator and an armature winding group consisting of 23 single coils wound 50 times in a flat stacked arrangement.

Separately, 70 parts by weight of an unsaturated polyester resin (trade name #7596, manufactured by U-Pica Japan) dissolved in styrene as a polymerizable crosslinking monomer, 30 parts by weight of a low shrinkage agent (A
-80, manufactured by U-Pica Japan), MMA as a blowing agent
- 10 parts by weight of microcapsules containing isoptane in an acrylonitrile copolymer, 5 parts by weight of aluminosilicate balloons (trade name 200/7, manufactured by Filite) as micro hollow spheres, τ-butyl perbenzoate as a polymerization initiator 1 part by weight, 200 parts by weight of calcium carbonate as a filler, and 3 parts by weight of zinc stearate as a mold release agent were mixed in a kneader to prepare a putty-like thermosetting resin.

The above armature winding is set in a mold that has been preheated to 150℃±3deg, and a thermosetting resin is placed on the center part of the armature winding, that is, the terminal part of the commutator side winding of the armature winding. did. Next, the mold is clamped and held in that state for 5 minutes, and then the mold is opened to obtain a minimum thickness of 2, which is made integrally rigid with thermosetting resin.
A flat coreless armature with an outer diameter of 92 mm was obtained.

In the above coreless armature, the density of the cured thermosetting resin at the end portion of the armature winding on the commutator side is
The density of the cured product at the winding end portion on the opposite commutator side was 1.05 g/cc. Also, the moment of inertia of this iron-free armature is 0.760Kg- ^cm2 , and the temperature is 120℃.
It was able to withstand centrifugal force of 10,000 rpm.

Comparative Example 1 The same armature winding as in the example was set in a transfer molding die and molded with an epoxy resin molding material at 150°C for 5 minutes to obtain a coreless armature having the same dimensions as in the example. In this coreless armature, the density of the thermosetting resin cured material at the commutator side winding end portion and the anti-commutator side winding end portion of the armature winding are both
It was 1.80g/cc. Moreover, the moment of inertia of this coreless armature was 0.937 Kg-cm ² .

As described above, according to the manufacturing method of the present invention, a thermosetting resin containing an inorganic filler used in conventional iron-core armatures is used with a density (about 1.8 g/cc) that is essentially the same as that of a thermosetting resin containing an inorganic filler. We achieved a reduction in inertia of approximately 20% while maintaining the same basic characteristics required for a coreless armature, such as strength and dimensional stability at high temperatures. This makes it possible to easily obtain an ironless motor with better control response than in the past.

Comparative Example 2 Among the conditions of the example of the present invention described above, an armature was manufactured under the same conditions without using micro hollow spheres, and the armature A in the example described above and the armature in Comparative Example 2 were manufactured. The mechanical strength was compared with armature B. Armature B cracked at 7,000 rpm under 120°C conditions, whereas electrode A according to the present invention did not crack at 10,000 rpm under 120°C conditions as described above.

In this way, the present invention makes it possible to easily obtain an iron-core motor with excellent reliability and strength.

Claims (1)

[Claims] 1. In a method for producing a coreless armature in which a thermosetting resin is polymerized and hardened in a mold to make at least the armature winding part an integral rigid body, the basic resin is polymerized and hardened by heating at least the base resin. A thermosetting resin containing a foaming material, a foaming agent that foams when heated, and a plurality of microscopic hollow spheres made of an inorganic material with a microscopic diameter is used. The thermosetting resin is placed or filled in the winding end portion of the wire on the commutator side, and some of the micro hollow spheres are destroyed by the pressure during mold clamping, and heated after mold clamping to form the thermosetting resin. The encapsulated foaming agent is expanded, and the expansion pressure causes the thermosetting resin to fill the inside of the mold including the end portion of the coil opposite to the commutator, and is made into an integrally rigid body by polymerization and curing. A method for manufacturing a iron-free armature.