Abstract: Hardening is accomplished by heating a longitudinal section of a workpiece such as an odd-shaped bar, and by quenching while constraining the workpiece section in dies. The quenching is executed while the workpiece is pressed in a direction perpendicular to its longitudinal direction by a pressing device which is installed adjacent to the workpiece section constrained in the dies. Warping by quenching can thus be minimized in odd-shaped workpieces, such as an automobile steering rack bar.

Abstract: This invention provides a method and apparatus for quenching a tubular workpiece such as cylindrical tubes or different-shaped tubes, which are difficult to be exerted constraining force for preventing warping especially in case of thinner thickness. Warping is prevented by applying a constraining force which is increased from beginning of the quenching to termination thereof, corresponding to increase of elasticity limit stress in accordance with temperature drop of the workpiece. Furthermore, apparatus for carrying out the method for quenching a tubular workpiece are offered, wherein the apparatus are provided with a pressure controller for pressure rolls or dies, thereby the pressure controller changes setting input for the pressure during the quenching.

Abstract: A constrained quenching apparatus is provided for hardening a workpiece such as an asymmetrical bar which has a notable tendency to warping when quenched, without warping the workpiece. The apparatus comprises a set of two or more dies having plural projections provided on the inner side thereof, the projections coinciding with the contour of the workpiece when the dies are closed so that their die faces in contact with one another, and having plural recesses therein defined by the projections. The recesses are provided with one or more cooling liquid blow holes. The apparatus does not exert pressure on the workpiece at the start of the quenching when the workpiece is soft, so the flattening of the hollow workpiece such as a pipe, can be prevented.

Abstract: The present invention relates to an apparatus for continuous-direct-resistance heating of long-length articles wherein the travelling long-length article is made to contact with roll electrodes disposed in a specified spacing, then made to pass through an annular transformer disposed between the roll electrodes.Conductive members with sufficiently less electrical resistance than that of the long-length article located between the both electrodes are disposed on the periphery of the transformer with the both ends thereof connected to the roll electrode through a slider, thereby a current being induced in the long-length article with the conductive member as the retrace, which heats the long-length article having a higher resistance very efficiently, but does not result in an external voltage nor any electrical hazards along the production line in which the apparatus is installed.

Abstract: The present invention relates to an apparatus for continuous-direct-resistance heating of long-length articles wherein the travelling long-length article is made to contact with roll electrodes disposed in a specified spacing, then made to pass through an annular transformer disposed between the roll electrodes.Conductive members with sufficiently less electrical resistance than that of the long-length article located between the both electrodes are disposed on the periphery of the transformer with the both ends thereof connected to the roll electrode through a slider, thereby a current being induced in the long-length article with the conductive member as the retrace, which heats the long-length article having a higher resistance very efficiently, neither resulting in an external voltage, nor causing electrically any obstacle to the production line in which the apparatus is installed.

Abstract: An apparatus for manufacturing a core wire for use in laying optical fibers over a long distance produces a plurality of continuous corrugated deep grooves in a wire that are capable of holding therein the optical fibers longitudinally along the peripheral surface of the wire. An endless raw wire material of circular cross section is formed by the apparatus into a wire of square cross section through plastic processing and thereafter the wire is formed into a core wire of a flower patterned cross section with a plurality of petals having corrugated deep grooves in the periphery thereof continuously longitudinally thereof through a rolling device. In addition, the core wire so constructed is formed into a core wire with spiral corrugated deep grooves formed in the peripheral surface thereof. The rolling means has forming rolls equal in number to the number of ridges of the square wire, and each such roll having two perfect corrugated convex portions formed widthwise on the peripheral surface thereof.

Abstract: Apparatus and method for forming a reinforcing cage for a prestressed concrete pile, in which the cage includes a set of main steel bars arranged in a circular pattern and an auxiliary wire which is helically wound around and welded at its crossings with the steel bars, that prevents any crossings from being welded when the current for welding is either insufficient in magnitude or not present and that prevents any unwelded crossings from being subsequently tempered.