Abstract: A one-pack type liquid epoxy resin composition for balancing rotators comprises an epoxy resin, a curing agent, a curing accelerator, an inorganic filler, and a thixotropic agent as main components, wherein said curing agent is dicyandiamide or a dibasic acid dihydrazide and said curing accelerator is a tertiary amino group-containing compound obtained by reacting a polyfunctional epoxy compound, a compound having a tertiary amino group and at least one active hydrogen in the molecule, and a carboxylic acid anhydride. Further, a method for balancing a rotator comprises correcting unbalance of the rotator caused at rotation by applying a balancing material consisting of the above epoxy resin composition to the rotator by an automatic unbalance-correcting apparatus.

Abstract: Grooves in an article such as a commutator are filled with a soft brittle material before a grooved surface of the article is cut. With the grooves thus filled, the cutting is performed continuously and smoothly without involving formation of burrs projecting into the groove. The soft brittle material includes a water soluble material which can easily be removed from the grooves by merely immersing the article in water. Preferably, the soft brittle material comprises a sublimable material which is self-vanishing or disappearing as it undergoes sublimation to the vapor state when it is left to stand in the atmosphere.

Abstract: The method and apparatus for correcting the dynamic balance of a rotating body, whereby the correction of the dynamic balance of a rotating body is achieved by fixing a correcting agent on the rotating body after the position of the dynamic unbalance and the amount of the dynamic unbalance in the rotating body are measured, are so constructed as to detect whether or not the correcting agent fixed on the rotating body is protruding from a prescribed configuration of the rotating body. Therefore, the method and the apparatus are capable of not only correcting a dynamic unbalance of a rotating body, but also detecting the protrusion of the correcting agent fixed on the rotating body.

Abstract: The present invention relates to a method and apparatus for charging a high-viscous material in a material tank into a charging tank. The high-viscous material, namely, putty is used preferably as a material for correcting the dynamic unbalance of a rotary body. When the material is charged from the material tank into the charging tank through a nozzle, the pressure of air in the charging tank is reduced and the pressure of air in the material tank is increased to drop the high-viscous material in droplets without taking air thereinto and air which has permeated into the material in the material tank can be removed.

Abstract: A balancing putty for use in balancing rotation of a rotary part including:(a) an epoxy resin;(b) a curing agent capable of curing the epoxy resin when heated at a temperature of 60.degree. C. or more,(c) a first, finely divided inorganic filler having a specific gravity of 4.0 g/cm.sup.3 or more; and(d) a second, finely divided inorganic filler having a specific gravity of less than 4.0 g/cm.sup.3, the balancing putty having a density of at least 2.0 g/cm.sup.3 and a consistency of 1-12 mm in terms of penetration.

Abstract: An improved commutator for an electric motor and a method of making the same wherein the outer surface of a commutator sleeve molded of a synthetic resin is coated with an insulating coating layer of an electrically insulating coating material. The molded commutator sleeve thus coated is protected from oxidative degradation and cracking which would otherwise result in removal of a commutator bar and insulation failure.

Abstract: A rotor for printed-wiring motors includes a flat disk-like non-iron armature mounted on a hub secured to a rotating shaft, the armature being composed of at least two sheet coil assemblies bonded together under heat and pressure with a first thin insulating disc disposed therebetween. Each of the sheet coil assemblies is composed of a pair of sheet coils bonded together under heat and pressure with a second thin insulating disc disposed therebetween. Both the first and second insulating disc are formed of a web of aramid fiber coated with an insulating bonded adhesive.

Abstract: Grooves in an article such as a commutator are filled with a soft brittle material before a grooved surface of the article is cut. With the grooves thus filled, the cutting is performed continuously and smoothly without involving formation of burrs projecting into the groove. The soft brittle material includes a water soluble material which can easily be removed from the grooves by merely immersing the article in water. Preferably, the soft brittle material comprises a sublimable material which is self-vanishing or disappearing as it undergoes sublimation to the vapor state when it is left to stand in the atmosphere.