Abstract: A disinfection apparatus for drainage piping of sanitary equipment includes a cleansing tank, a toilet bowl, and a drainage pipe connected to the toilet bowl. When the sanitary equipment is used, a fixed amount of cleansing water is supplied to the toilet bowl from the cleansing tank, and the cleansing water after cleansing the toilet bowl is drained from the drainage pipe. A sensor senses a supply of water to the cleansing tank. A chemical liquid pump supplies a fixed amount of chemical liquid from a chemical liquid tank to the cleansing tank. A control unit is configured to operate the chemical liquid pump by means of a water supply sensing signal from the sensor to supply a fixed amount of chlorine dioxide to the cleansing tank, thereby maintaining the concentration of chlorine dioxide in the cleansing water within the cleansing tank at a fixed concentration.

Abstract: An electric discharge machining method which is practiced with stable machining condition and with high machining efficiency. The condition which, in machining a workpiece, tends to place the gap between the electrode and workpiece in unstable state is detected, and the period of time for which the condition thus selected lasts is set so that the discharge energy of a pulse voltage applied across the electrode and the workpiece is reduced for the period of time thus set. Therefore, in the electric discharge machining method of the invention, the machining operation is maintained stable with high machining efficiency at all times.

Abstract: In a machining device comprising: a machining vessel containing a machining solution in which a workpiece has been immersed; air stream producing elements for producing a stream of air above the surface of the solution in the machining vessel in parallel with the solution surface; and air stream sucking elements for sucking the stream of air thus produced, thereby to remove gas produced from the solution during machining, the air stream producing elements and/or the air stream sucking elements are moved vertically to a predetermined height from the solution surface according to the level of the machining surface in the machining vessel, so that the gas thus produced is positively removed.

Abstract: To simultaneously machine a plurality of workpieces, 6, 6a a continuous wire electrode 2 supplied by a feed unit 1 is reversed by a pulley 21 below the movable mounting table 7 after passing down through one of the workpieces, and led back up through the other workpiece to a tensioning takeup unit 11. The wire electrode runs 2, 2a are maintained parallel by upper guides 3, 3a secured to a common mounting plate 20, and relative movement between the electrodes and workpieces is controlled to discharge machine identical configurations in both of them.