Abstract: An apparatus for continuously producing a tube having helical grooves in its surface comprises a first drum, a flier having an axis intersecting the axis of the first drum at right angles therewith and rotatable around the first drum, and a second drum. One of the two drums serves as a pay-off drum for paying off a tube having straight grooves in its inner surface, while the other drum serves as a take-up drum for winding thereon the helically grooved tube obtained. At one side of the pay-off drum where the paid-off straight-grooved tube is to be transferred to the flier, a device is provided for preventing the torsion of the tube produced by the rotation of the flier from being transmitted toward the pay-off drum. A correcting device is provided between the flier and the take-up drum for remedying deformation of the helically grooved tube. With the rotation of the flier, the straight-grooved tube is twisted, whereby the straight grooves are deformed to helical grooves to afford a helically grooved tube.

Abstract: An apparatus for continuously producing a tube having helical grooves in its inner surface comprising a tube twising rotary frame, a pay-off drum mounted on the rotary frame for paying off a tube having straight grooves in its inner surface, a nozzle provided at the front end of the rotary frame and having an adjustable inside diameter for sending out the paid-off tube forwardly of the rotary frame, and at least one pair of catching rollers provided in front of the rotary frame and disposed close to the nozzle for holding the sent-out tube. Each of the catching rollers is formed in its peripheral surface with a groove of semicircular cross section in conformity with approximately one-half of the outer periphery of the tube. With the rotation of the rotary frame, the straight-grooved tube is twisted between the nozzle and the catching rollers, whereby the straight grooves are deformed to helical grooves.

Abstract: A double twisting machine for winding a wire around a take-up roll has two motors for directly and separately driving each end of a flyer thereby eliminating the need for a driving shaft, driving pulleys and timing belts which substantially reduces the amount of noise generated by the machine and reduces its overall size.

Abstract: A bearing device having a boundary layer of pressurized gas comprises an enclosed member of a box type, which has a semi-cylindrical surface of a semi-circular shape in its transverse cross section. The enclosed member has a plurality of minute holes in the aforesaid semi-cylindrical surface, which holes are directed towards the imaginary center of the aforesaid semi-cylindrical surface, and a pressurized air inlet provided in one wall of the enclosed member. A boundary layer of pressurized air is formed between the semi-cylindrical surface and an outer surface of a rotary shaft mounted thereon due to the injection of air therebetween through a plurality of minute holes defined in the semi-cylindrical surface of the enclosed member. Thus, the rotary shaft is supported by the pressurized air thus introduced, so that the rotary shaft may be rotated in a stable condition, with its center of rotation in coincidence with the imaginary center of the aforesaid semi-cylindrical curved surface.