Abstract: A method for manufacturing a one-side electrogalvanized steel strip, which comprises: continuously causing a steel strip to travel through an electrogalvanizing bath in an electrogalvanizing tank; arranging an electrode plate in the electrogalvanizing bath in the electrogalvanizing tank in parallel to a one-side surface to be electrogalvanized of the steel strip; electrogalvanizing the one-side surface of the steel strip; arranging a spray nozzle toward the other surface not electrogalvanized of the steel strip which has passed through the electrogalvanizing tank; ejecting any one of an aqueous solution containing a weak acid of from 0.1 to 5.0 wt.

Abstract: Disclosed is an electric discharge machining method in which the electric discharge working gap between an electrode and a work piece to be machined is automatically adjusted. To detect the condition of the discharge working gap, a low voltage pulse is applied each time a plurality of high voltage pulse for electric discharge machining are applied for a predetermined time. The working current resulting from the application of each low voltage pulse is detected to control the feeding of the electrode and thereby to automatically adjust the discharge working gap to a predetermined value.

Abstract: There is disclosed an apparatus for giving a satin finish to the surface of a crowned roll. A plurality of electrode heads are divided and arranged along the axis of rotation of the crowned roll to be worked, and one or a plurality of rectangular electrodes are mounted at a predetermined spacing on each of the electrode heads. The discharge gap of each rectangular electrode is controlled by a servomechanism at a predetermined value and it is also fed traversely a predetermined distance by a traverse feed mechanism. The electrode is rectractably mounted on the electrode head and it is fixed in position so that the discharge surface of the electrode is projected into contact with the roll surface of the crowned roll. The discharge electrode surface of each rectangular electrode is initially flat and this discharge surface is consumed to conform with the shape or contour of the roll surface upon initiation of discharge.

Abstract: There is disclosed an electric discharge machining method in which the discharge working gap between an electrode and a work piece is automatically adjusted to prevent the occurrence of a streaky pattern in the surface of the work piece due to variation in the amount of machining. After a plurality of high voltage pulses have been applied for a predetermined time across the working gap, a low voltage pulse is applied across the working gap. In response to the application of the low voltage pulse, the feeding of the electrode is controlled by a pulse motor in a direction to reduce the working gap, and as soon as the discharge is started the feed control is stopped and the discharge machining is then effected in response to the application of high voltage pulses.