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RABBIT EAR. Recess in die corner to allow for wrinkling or folding of the blank.
RAM. The powered, movable portion of the power press brake structure, with die-attachment surface, which imparts the pressing load through male dies onto the piece part and against the stationary portion of the press brake bed. (See SLIDE.)
RECRYSTALLIZATION. A process whereby the distorted grain structure of cold worked metals is replaced by a new, strain-free grain structure during annealing above a specific minimum temperature.
REDRAWING. The second and successive deep drawing operations in which the cuplike shells are deepened and reduced in cross-sectional dimensions (sometimes in wall thickness, by ironing). Redrawing is done in both single-action dies and in double-action dies.
REDUCTION IN AREA. The difference between the original cross-sectional area and the smallest area at the point of rupture, usually stated as a percentage of the original area.
REPEAT. An unintended or unexpected successive stroke of the press resulting from a malfunction.
RESILENCE. The amount of energy stored in a unit volume of metal as a result of applied loads.
RESTRIKING. Cold striking of a finished forging to remove distortions after it has been quenched.
RIB. A long, V-shaped or radiused indentation used to strengthen large panels.
ROLLER STRAIGHTENING. A process involving a series of staggered rolls of small diameter between which rod, tubing, and shapes are passed for the purpose of straightening. The process consists of a series of bending operations.
ROLL FORMING. (1) An operation used in forming sheet. Strips of sheet are passed between rolls of definite settings that bend the sheet progressively into structural members of various contours, sometimes called "molded sections.'' (2) A process of coiling sheet into open cylinders.
ROLL THREADING. Applying a thread to a bolt or screw by rolling the piece between two grooved die plates, one of which is in motion, or between rotating grooved circular rolls.
ROTARY BLADE. A shearing tool whose cutting edge makes a complete revolution about a fixed axis.
ROTARY SHEAR. A cutting machine with sharpened circular blades or disk-like cutters used for trimming edges and slitting sheet and foil.
ROTARY SWAGER. A machine used for pointing wire rod and tubing and for initial working of moderately brittle metals and alloys in which a pair of tapered dies is used. The dies are rotated and are pressed intermittently against the work material by an eccentric action.
RUBBER PAD FORMING. A forming operation for shallow parts in which a confined, pliable, rubber pad attached to the press slide is forced by hydraulic pressure to become a mating die for a punch or group of punches that have been placed on the press bed or baseplate. A process developed in the aircraft industry for limited production of a large number of diversified parts. This is the Guerin process. Although this process was used originally on aluminum and magnesium alloys it is now used on light gages of mild and stainless steel.
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