Abstract: A rotor core includes a shaft hole, into which a shaft is inserted, and keys, which are protrusions corresponding to keyways of the shaft. A radial distance, which is the distance from the center of the shaft hole to an inner wall varies depending on the position in the circumferential direction of the shaft hole. The shaft hole includes key regions and increased diameter regions, in each of which the radial distance is longer than the radius of the shaft. Keys are respectively arranged in the key region. The shaft hole also includes contact regions, in which the shaft and the inner wall come into contact with each other when the shaft is inserted into the shaft hole. The contact regions are each located between the key regions or between the increased diameter regions. The contact regions are arranged at equal intervals in the circumferential direction.

Abstract: An adequate control of a pH of circulating water circulating through a wet paint booth enables an efficient coagulation treatment of a paint included in the circulating water. A method for treating circulating water circulating through a wet paint booth and including a paint includes treating the paint included in the circulating water by adding an alkaline solution of a phenolic resin to the circulating water, and adjusting a pH of the circulating water to 6.5 to 8.0. An amount of the alkaline solution of the phenolic resin added to the circulating water is increased when the pH of the circulating water is a predetermined value of 8.0 or less. An acidic aluminum salt is further added to the circulating water. An amount of the acidic aluminum salt added to the circulating water is increased when the pH of the circulating water is a predetermined value of 6.5 or more.

Abstract: A wet paint spray booth treating agent includes sepiolite alone or further accompanying cationic polymer or amphoteric metal compound. In a method of treating a wet paint spray booth, the sepiolite alone or further accompanying the cationic polymer or the amphoteric metal compound is added. The wet paint spray booth treating agent and a method of treating a wet paint spray booth improve the effect of reduction in tackiness and decrease the load of agents to prevent the corrosion of furnishings. The sepiolite is a fibrous mineral containing chain structures having lots of micropores so that the sepiolite can reduce the tackiness of the paint due to reaction with the particles of the paint in such a manner to adsorb the particles in the micropores thereof.

Abstract: In a method of treating a wet paint spray booth, the sepiolite alone or further accompanying the cationic polymer or the amphoteric metal compound is added. The wet paint spray booth treating agent and a method of treating a wet paint spray booth improve the effect of reduction in tackiness and decrease the load of agents to prevent the corrosion of furnishings. The sepiolite is a fibrous mineral containing chain structures having lots of micropores so that the sepiolite can reduce the tackiness of the paint due to reaction with the particles of the paint in such a manner to adsorb the particles in the micropores thereof. Since both the particles of the paint and the particles of the sepiolite are negatively charged, when the cationic polymer or the amphoteric metal compound is added in combination with the sepiolite, the electrical repulsion is reduced so that the particles of the paint become easy to be adsorbed to improve the effect of the reduction in the tackiness.

Abstract: A wet paint spray booth treating agent comprising a melamine--aldehyde acid colloid solution, a nitrogen atom-containing organic compound and an anionic water soluble high molecular weight dispersant. A method for the treatment of a wet paint spray booth which comprises adding a melamine--aldehyde acid colloid solution, a nitrogen atom-containing organic compound and an anionic water soluble high molecular weight dispersant to a recirculating washing water in a wet paint spray booth.