Abstract: A rectilinear motion apparatus includes two shafts arranged in parallel, a driving motor and a driving pulley coupled to one of the two shafts, an idler pulley coupled to the other of the two shafts, an endless toothed belt arranged between the driving pulley and idler pulley, and a slider disposed between the driving pulley and the idler pulley. The slider includes a first moving pulley and a second moving pulley of a diameter larger than a diameter of the first moving pulley. The first and second moving pulleys are integrally fixed to one another for rotation about the same axis so as to rotate simultaneously. A first pair of guide rollers are disposed on the slider adjacent the first moving pulley to guide a lower run of the toothed belt, and a second pair of guide rollers are disposed on the slider adjacent the second moving pulley to guide an upper run of the toothed belt.

Abstract: A method of applying a synthetic resin layer to an outer surface of a metal part, comprising heating the metal part to a temperature higher than a melting point of a synthetic resin, embedding the heated metal part within a powdered mass of the synthetic resin, thereby melting a portion of the powdered mass surrounding the outer surface of the heated melt part, holding the heated metal part within the powdered mass for a time period sufficient to permit the molten portion of the powdered mass to be coated on the outer surface of the heated metal part as the synthetic resin layer, removing the metal part coated with the synthetic resin layer from the powdered mass, and maintaining the removed metal part at a temperature higher than the melting point and lower than a thermal decomposition point of the synthetic resin, to hold the deposited resin layer in a molten state for a suitable length of time, in order to allow the escape of possibly entrapped air from the resin layer.

Abstract: A broaching method for finishing an outer peripheral surface of a resin layer of a resin-coated lobe-type rotor for a rotary fluid machine of a Roots type, which includes the steps of forming, with a leading grooving cutter, at least one chip-breaker groove in the outer peripheral surface of the resin layer, such that the chip-breaker groove extends in a broaching direction parallel to an axis of rotation of the rotor. The method further includes the steps of finishing at least a portion of the outer peripheral surface of the resin layer with a trailing finish cutter having a cutting edge contour corresponding to the portion of the outer peripheral surface of the resin layer, which is finished by the finish cutter after the chip-breaker groove is formed therein by the grooving cutter. A composite broach or formed broach having the grooving and finish cutters is fed such that the grooving cutter leads the finish cutter in the broaching direction.

Abstract: A method and apparatus for applying a synthetic resin layer to an outer surface of a metal part while the metal part is placed within a powdered mass of a thermally fusible synthetic resin. The metal part within the powdered mass is induction-heated to a temperature higher than a melting point and lower than a thermal decomposition point of the synthetic resin, in order to melt a portion of the powdered mass surrounding the heated metal part, and thereby permit the molten portion of the powdered mass to be deposited as the synthetic resin layer on the outer surface of the heated metal part. To facilitate the placement of the metal part in the powdered mass, air may be blown into the powdered mass to keep the mass in a fluid state.

Abstract: A Roots type pump comprising a pair of mating lobed rotors which are supported by rotor shafts, respectively. Each rotor is fixed to the corresponding rotor shaft by a pin forcibly inserted in a through hole provided through the rotor and rotor shaft. The outer surface of each rotor is surrounded by a coating layer of plastic material, at which the through hole has end openings having cross sectional dimensions greater than that of the substantial part of the through hole.

Abstract: A Roots-type rotary fluid machine having resin-coated rotors fluid-tightly accomodated in a chamber formed in a housing structure which consists of a generally cup-shaped main housing body having a bore closed at its one end and open the other end, and a covering member which closes the open end of the bore in the housing body. The housing body includes a fillet portion which bridges an inner flat surface defining the bottom of the bore and facing one end face of each rotor, and an inner peripheral surface defining the periphery of the bore and facing the outer peripheral surface of each rotor. The fillet portion is formed along a line of intersection of extensions of the inner flat surface and the inner peripheral surface of the housing body, and inwardly into the bore from this line of intersection. The fillet portion has a generally triangular shape in cross section taken in a direction perpendicular to the above line of intersection.

Abstract: A broaching method for finishing an outer peripheral surface of a resin layer of a resin-coated lobe-type rotor for a rotary fluid machine of a Roots type, which includes the steps of forming, with a leading grooving cutter, at least one chip-breaker groove in the outer peripheral surface of the resin layer, such that the chip-breaker groove extends in a broaching direction parallel to an axis of rotation of the rotor. The method further includes the steps of finishing at least a portion of the outer peripheral surface of the resin layer with a trailing finish cutter having a cutting edge contour corresponding to the portion of the outer peripheral surface of the resin layer, which is finished by the finish cutter after the chip-breaker groove is formed therein by the grooving cutter. A composite broach or formed broach having the grooving and finish cutters is fed such that the grooving cutter leads the finish cutter in the broaching direction.

Abstract: A synthetic resin rack guide in a rack-and-pinion type steering gear is provided with a projection formed on an outer peripheral surface at an end portion which is in contact with a rack bar. The projection is designed in such a manner that a diameter thereof after shrinkage due to annealing is equal to or slightly larger than an inner diameter of a guide hole for receiving the rack guide. With this arrangement, an abnormal noise created between rack teeth and a pinion may be prevented.