JPS6245784B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method of manufacturing a coreless armature in which at least the armature winding portion is made integrally rigid by heating 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 used as relatively large coreless armatures ranging from several watts to several hundred watts, the properties required for integral rigidity are sophisticated, such as strength at high temperatures, dimensional stability, and heat resistance. An integrated rigid body that can meet impact resistance, electrical insulation properties, and long-term heat deterioration resistance is required. Therefore, transfer molding is applied to at least the armature winding portion of the above-mentioned coreless armature using a thermosetting resin molding material that usually contains 50% or more of an inorganic filler, and prepreg hardening is further applied to a part of the surface of the armature winding. Iron-free armatures that utilize the combined effect of providing layers have been put into practical use. The relatively large coreless armatures mentioned above, ranging from a few watts to several hundred watts, are often used as motors to perform incremental motion by taking advantage of their quick response, and are used in fields that cannot be followed by pulse motors. There are many. i.e. magnetic disk,
These fields include facsimiles, automatic welding machines, industrial robots, and machine tools. However, as the performance and precision of these devices have increased, there has been a desire for a motor with even higher control responsiveness, that is, a low-inertia iron-core armature. The present invention has been made in view of the above-mentioned demands, 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 heating and curing a thermosetting resin. It is. That is, in a mold, at least the armature winding portion is filled with a thermosetting resin, a foaming agent, or microcapsules encasing the same, and a foaming initiator, and the foaming agent or the microcapsules encasing it are filled with the lowest expansion temperature or slightly below. The foaming initiator is decomposed at a low temperature to cause foaming to occur at a temperature lower than the polymerization temperature of the thermosetting resin, and the thermosetting resin is quickly polymerized to reduce the foaming pressure from inside the thermosetting resin. This method is characterized by completely filling the mold with the thermosetting resin. The present invention will be explained in more detail below. The iron core armature that is the object of the present invention is used in motors ranging from several watts to several hundred watts, and if it is a wire-wound type iron core armature, it can be flat or cup-shaped. There is no problem even if it is. Further, the armature winding may be an unshaped armature winding in which a predetermined number of electric wires are wound and not shaped into a predetermined shape, or a shaped armature winding. Further, in the manufacturing method of the present invention, the thermosetting resin may be solid at room temperature or putty-like, but it is preferable to use transfer molding for solid resins and compression molding for putty-like resins. The thermosetting resin used in the present invention is a basic resin,
It consists of a compound capable of curing this, or a polymerization initiator, a foaming agent, a filler, and fibers added as necessary, a mold release agent, and a coloring agent, preferably with a foaming ratio of 1.5.
It refers to a foamable resin composition of ~2.5 times the size of the foamed resin composition, and in addition, a woven or nonwoven fabric made of organic or inorganic fibers, or a prepreg body based on these, is added to a part of the surface of the armature winding of the iron-core armature. It may be used as a surface material for a sandwich-like composite body by using it as appropriate, or it may be configured such that a cured prepreg layer is provided only on one surface of the armature winding. The thermosetting resin used in the present invention, that is, a foaming thermosetting resin consisting of a basic resin, a compound capable of curing it, a polymerization initiator, a foaming agent, a filler, and optionally added fibers, a mold release agent, and a coloring agent. The resin composition will be explained below. The basic resin includes unsaturated polyester, diallyl phthalate, urethane, phenol, epoxy, urea, etc., and among them, unsaturated polyester and diallyl phthalate are preferred. The unsaturated polyester used in the present invention refers to α, β unsaturated carboxylic acids or these and saturated dicarboxylic acids, further saturated,
An unsaturated polyester obtained by an esterification reaction between organic acids including unsaturated monocarboxylic acids and alcohols, that is, glycols, polyhydric alcohols, and monohydric alcohols, is dissolved in a crosslinking monomer that can be polymerized with the unsaturated polyester. It usually contains a small amount of polymerization inhibitor and, if desired, contains polystyrene, polyethylene, polymethyl methacrylate and copolymers, polyvinyl chloride, polycaprolactone saturated polyester as low shrinkage agents. Furthermore, diallyl phthalate is a prepolymer such as diallyl orthophthalate, diallyl isophthalate, tetrabromo diallyl phthalate, tetrachlorodiallyl phthalate, or a copolymer thereof, and contains monomers such as butadiene, urethane, etc., if desired. Alternatively, it refers to a material containing thermoplastic resin such as polystyrene. Curing agents or polymerization initiators include organic peroxides such as benzoyl peroxide, methyl ethyl ketone peroxide, etc. in the case of the above basic resins, and metal salts such as cobalt naphthenate, cobalt octoate, and triethanol as accelerators. Amines, amines such as diethylaniline, etc. are optionally used. Examples of the blowing agent include substances that generate gas when heated, such as dinitrosopentamethylenetetramine, azodicarbonamide, toluenesulfonylhydrazide, and azoisobutylnitrile, or acrylonitrile-vinylidene chloride copolymer, polystyrene, and polyα-methylstyrene. , substances that generate gas when heated in the fine capsules such as polyisobutylene, or aliphatic and cycloaliphatic hydrocarbons that do not dissolve the fine capsule substances such as propane, pentane, hexane, heptane, petroleum ether, dichloropentane cyclopentadiene, etc. is impregnated with foaming agent. In addition, fillers such as calcium carbonate, hydrated alumina, and silica, fibers such as glass and vinylon, mold release agents such as zinc stearate and calcium stearate, and colorants such as titanium oxide and phthalocyan blue are added as appropriate. used. Polymerization and curing of the foamable thermosetting resin composition is usually accompanied by heat generation. The viscosity increases due to polymerization and curing while generating heat, and finally hardening occurs. Even when polymerization starts at a relatively low temperature, the temperature usually rises to a fairly high temperature once polymerization has started, but at that point the viscosity increases significantly and the foamable thermosetting resin composition does not foam. , the mold is not completely filled. Therefore, it is necessary for the blowing agent or the microcapsules surrounding it to reach a temperature at which it expands while the viscosity is still low at the beginning of polymerization. If the temperature is below the minimum expansion temperature or close to that temperature, due to the time delay in heat conduction, the expansion temperature of the foaming agent or the microcapsules enclosing it will be reached by the polymerization heat after polymerization starts. The viscosity has already increased significantly, the foaming ratio of the cured product has decreased, and the desired iron-free armature cannot be obtained. That is, in order to raise the temperature to the inside of the system above the expansion temperature of the foaming agent or the microcapsules surrounding it without using polymerization heat, it is necessary to make the armature-integral rigidity temperature higher than the foaming temperature. If the foaming agent or the microcapsules enclosing them are expanded in the mold before polymerization starts, if left in that state for a long time, the foamed bubbles or microballoons may be destroyed again by the molten resin or crosslinked monomer. Sometimes. Therefore, it is desirable that the armature winding is quickly polymerized, its viscosity increases, and hardened when it is embedded in the mold.As long as the viscosity increases to a certain extent, even if the bubbles or microballoons are destroyed, there will be no voids. It remains as a small cell, and the desired low inertia coreless armature can be obtained. Compounds capable of curing the basic resin,
Alternatively, the polymerization initiator is preferably an initiator that decomposes at a temperature that is slightly lower than or approximately the same as the lowest temperature at which the blowing agent or the microcapsules enclosing it can expand. Examples are shown below. Example 1 An armature winding consisting of a commutator and an armature winding group in which 23 single coils of insulated wire having a self-bonding layer of φ0.25 were wound 50 times and arranged in a flat shape was prepared. Further, a foamable thermosetting resin composition having the following composition was obtained using microspheres containing isobutane in microcapsules of acrylonitrile-vinylidene chloride copolymer. Unsaturated polyester 70 parts by weight Styrene 80 parts by weight Microsphere 3.5 parts by weight Benzoyl peroxide 1 part by weight Calcium carbonate 150 parts by weight Zinc stearate 2 parts by weight After mixing the above in a kneader, 10 g was loaded into the mold in advance. Place it in the center of the armature winding of

[Table] In the above example, the armature winding weight is 52.9g, and the commutator is
The foaming ratio of the foamable resin composition used in the examples is 1.9 to 2.2 times. As is clear from Table 1, the embodiment of the present invention achieved a total weight reduction of 18 to 20% compared to the conventional ironless armature. In other words, the motor achieves a reduction in inertia of 18 to 20% and operates with extremely excellent control response. Furthermore, since it is a coreless armature with a structure that includes many cells or balloons in the thermosetting resin that integrates the armature winding, armature shaft, and commutator, the cells or balloons have a sound absorbing function. As a result, the effect of reducing motor noise is also large. Further, according to the present invention, the foaming initiator is decomposed at the lowest expansion temperature of the foaming agent or the microcapsules enclosing it, or at a slightly lower temperature, and foaming is performed at a temperature lower than the polymerization temperature of the thermosetting resin, and the foaming is rapidly performed. Because thermosetting resin is polymerized with
The mold can be completely filled with the thermosetting resin, and a coreless armature of extremely high quality can be obtained.

Claims (1)

[Claims] 1. In a mold, at least the armature winding portion is filled with a thermosetting resin, a foaming agent, or microcapsules encasing the same, and a foaming initiator, and the foaming agent or the microcapsules encasing the same are filled with the lowest expansion temperature or lower. The foaming initiator is decomposed at a slightly lower temperature, and the thermosetting resin is foamed at a temperature lower than the polymerization temperature of the thermosetting resin. An ironless core formed by heating and curing the thermosetting resin to make the armature winding an integral rigid body, characterized in that the step of completely filling the mold with the thermosetting resin by using foaming pressure is essential. Method of manufacturing armature.