Abstract: A finishing gear hob whose shape is of a worm includes a working side with cutting edges K, which are in the form of a continuous equally-rising spaced cylindrical helix, and edges K are formed by the intersection of the rake faces A, i.e. the top surfaces of the worm, and the flanks B, i.e. the working sides of the worm. The number of cutting edges K equals to the thread number i of the worm, where i is a positive integer. The normal pitch P.sub.n of the working side of the worm is equal to the normal base pitch t.sub.b of the machined gear .pi.m.sub.n COS.alpha..sub.n where m.sub.n is the normal module of the machined gear; and .alpha..sub.n is the normal pressure angle at the reference circle of the machined gear. The lead angle .lambda. of the helix cutting edge is calculated by the formula Sin.lambda.=(im.sub.n COS.alpha..sub.n)/2R where R is the radius of cylindrical helix cutting edge K, and the helix lead P of the helix cutting edge P=(i.pi.m.sub.n COS.alpha..sub.n)/COS.lambda..

Abstract: This invention is related to the process and apparatus for applying stressed skin sheet coverings to large passenger vehicles. The apparatus for the process, provided by this invention includes a single phase transformer, conductors, electric contactors and a guiding apparatus. The present invention uses a specialized transformer, capable of producing a strong electric current of low voltage as an energy source, utilizing the steel skin sheet as a resistor element in the output circuit, welding the steel sheet onto the frame while the steel sheet is heated by the electric current passing through the sheet, thereby elongating the sheet at a set value due to the rise in temperature, cutting off the electricity and welding the upper and lower sides quickly onto the frame, thus finishing the process of skin covering and resulting in residual stresses within the steel skin sheet.