Abstract: A method of and an apparatus for fabricating a spiral fin in which a strip of material is bent with rolling by a pair of rolls while being imparted with a tension to reduce the speed at which the strip is drawn between the pair of rolls to reduce a compressive force applied to a portion of the strip corresponding to an outer edge portion of the spiral fin, thereby improving the forming limit of the spiral fin.

Abstract: A method for jointing two pipes such as an aluminum pipe and a copper pipe by friction welding. The aluminum pipe is inserted into a bore of a ring made of a heat resistant material, the bore having a straight section and a tapered section continuous from the straight section. The copper pipe has a tapered end peripheral surface. The copper pipe is pressed at its tapered end, in a rotating state, against the end of the aluminum pipe so as to expand the latter. As a result, an ironing is effected on the aluminum pipe by the straight section of the bore of the ring, such that the aluminum pipe overlies the straight section of the copper pipe in close contact with the latter. Consequently, the tapered surface of the copper pipe is friction welded to corresponding portion of the aluminum pipe while the latter is being backed up by the tapered section of the bore of the ring.

Abstract: A spider of loudspeaker having a base material in the form of a plain-woven fabric of warps and wefts each of which constituted by fibers of an inorganic material. The warps and wefts are coated with a thermosetting resin which in turn is coated with a thermoplastic resin. The spider thus formed is less liable to absorb the ambient moisture and, therefore, is free from distortion.

Abstract: Improvements in a plastic working process for face-centered cubic metals, and titanium and zirconium having close-packed-hexagonal lattice, which process utilizes a phenomenon that the ductility of these metals is increased at sub-zero temperatures, i.e., temperatures below 0.degree. C. This process includes the steps of (i) imparting plastic flow including at least a uniaxial tensile stress field a metal at a temperature below zero, (ii) subjecting the metal to plastic flow to an extent that the strain of the metal is within the limit of uniform elongation of the metal, and then to plastic flow including at least a uniaxial tensile stress field continuously thereafter, or (iii) using frost as a lubricant for plastic working at temperatures below 0.degree. C according to either one of the foregoing steps.

Abstract: This invention relates to an apparatus for production of metal powders of a low oxygen content, which are preferred as raw material powders for sintered bodies of a high toughness, according to the water atomizing method. More specifically, when a molten metal is sprayed in a limited space with use of a liquid crystal medium and cooled promptly, a metal powder results of a good moldability which has an oxygen content corresponding to 1/2 or less of the oxygen contents of metal powders prepared by conventional apparatuses and which is excellent in the size uniformity.