JPH01301976A - Screw rotor - Google Patents

Abstract

PURPOSE:To exhibit a large resistance against a force acting in a swing direction by engraving grooves or forming protrusions, on a metallic shaft, for including lead angles opposing to the lead angle possessed by a rotor. CONSTITUTION:A male screw rotor 1 comprises a metallic shaft 2 and a synthetic resin made rotor 3 for covering the shaft 2. The synthetic resin made rotor 3 is formed on the metallic shaft 2 by injection molding and equipped with 4 lines of screw on its periphery. Four lines of grooves 4 having lead angles opposite to the direction of the lead angles possessed by the rotor 3 engraved along the total length of the portion to be covered by the rotor 3 are engraved on the surface of the metallic shaft 2. When the synthetic resin made rotor 3 is under the process of injection molding, the synthetic resin enters the grooves 4 engraved on the surface of the metallic shaft 2 and hardens there.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a helical gear, a worm gear, and particularly a screw rotor suitable for a screw rotor of a screw compressor or a pump.

(Prior art and its problems) The screw rotor of a conventional screw compressor is manufactured by machining high-strength steel materials such as carbon steel for machine structures, and in particular, the screw is manufactured using a special processing machine. It was precisely cut using a single cutter or hob.

Therefore, this screw rotor not only requires a large number of man-hours to process the screw, but also has large variations in accuracy due to cutting errors.

Furthermore, since this screw rotor is entirely made of steel, it is heavy and therefore has a large inertia during rotation, requiring a large amount of power to start the screw rotor.

Therefore, in order to reduce the weight of the screw rotor, for example, as shown in Japanese Patent Application Laid-Open No. 59-32688,
It has been proposed to integrate a synthetic resin rotor with threads on the outer peripheral surface with a metal shaft by injection molding a synthetic resin to cover the metal shaft.

In this screw rotor, the synthetic resin rotor is joined to the metal shaft only by the adhesion force during injection molding, so when the screw rotor is twisted out of the mold or when this screw compressor is operated, the rotor When a load was applied to the screws on the outer periphery of the rotor, there was a risk that the rotor would separate from the shaft.

(Means for Solving the Problems) The present invention has been made to solve the above problems, and its purpose is to prevent the synthetic resin rotor from separating from the metal shaft. There is something to do.

In order to achieve this object, the present invention provides a screw rotor formed by injection molding a synthetic resin rotor onto a metal shaft so as to cover the rotor, wherein the metal shaft is covered with the rotor. One or more grooves or protrusions having a lead angle opposite to the direction of the lead angle of the rotor are carved on the surface of the portion where the rotor is formed.

(Function) Since the present invention has the above-mentioned configuration, during injection molding of the synthetic resin rotor, the synthetic resin hardens by entering into the grooves carved on the surface of the metal shaft or wrapping around the protrusions. do. Since this groove or protrusion runs in the opposite direction to the twisting direction of the screw, the synthetic resin that hardens into the groove or wraps around the protrusion will cause the synthetic resin rotor and metal shaft to move relative to each other. It exerts a large resistance against forces acting in the twisting direction.

(Embodiment) An embodiment in which the present invention is applied to a male screw rotor of a screw compressor is shown in FIGS. 1 to 4.

In Figures 1 to 4, a male screw rotor 1 includes a metal shaft 2 and a synthetic resin rotor 3 covering the metal shaft 2.
Consisting of

The synthetic resin rotor 3 is formed on the metal shaft 2 by injection molding, and has four threads on its outer peripheral surface. Four grooves 4 having lead angles opposite to the direction of the lead angle of the rotor are carved on the surface of the metal shaft 2 over the entire length of the portion covered by the rotor 3.

Note that a4 shown in the figure has a rectangular cross-sectional shape and is carved over the entire length of the portion covered by the rotor 3, but the cross-sectional shape, number, lead angle, and carved range of the grooves 4 can be arbitrarily selected. .

During injection molding of the synthetic resin rotor 3, the synthetic resin enters the grooves 4 carved on the surface of the metal shaft 2 and hardens.

After injection molding, the screw rotor 1 is removed from the mold while being rotated in the direction of the molding.

When the screw compressor is in operation, the male screw rotor 1 is rotated at high speed while meshing with the female screw rotor within the casing.

Since the groove 4 is twisted in the opposite direction to the chaining direction of the screw, the synthetic resin that has entered the groove 4 and hardened may be removed when the screw rotor 1 is removed from the mold or when the screw compressor is operated. It exerts a large resistance against the force that acts in a direction that twists the synthetic resin rotor and the metal shaft relative to each other.

Above, we have explained an example in which a groove is carved with a lead angle opposite to the direction of the lead angle of the rotor, but instead of this groove, a protrusion may be carved, and in this case, the synthetic resin has a protrusion. It hardens in a way that envelops the metal shaft, and, like the grooves, exerts a large resistance against forces that twist the rotor and metal shaft relative to each other.

(Effects of the Invention) In the present invention, in a screw rotor formed by injection molding a synthetic resin rotor onto a metal shaft so as to cover the rotor, the metal shaft is covered by the rotor. Because one or more grooves or protrusions with a lead angle opposite to the direction of the lead angle of the rotor are carved on the surface of the part,
During synthetic resin injection molding, the synthetic resin hardens by entering the grooves carved into the surface of the metal shaft or surrounding the protrusions, and acts in a direction that twists the synthetic resin rotor and the metal shaft relative to each other. This effectively prevents the synthetic resin rotor from separating from the metal shaft by exerting a large resistance force against the force exerted by the synthetic resin rotor.

Also, since it is sufficient to engrave the surface of the metal shaft,
Not only is the processing easier and cheaper than D-shaped or knurling, there is no risk of deforming the metal shaft during processing, and the torsion direction that acts on the synthetic resin rotor is The resistance to the force of will also increase.

[Brief explanation of the drawing]

1 to 4 show an embodiment in which the present invention is applied to a screw rotor, with the upper half of FIG. 1 showing a longitudinal section and the lower half showing a front view. 2 is a cross-sectional view taken along the line ■-n in FIG. 1, FIG. 3 is a front view of the metal shaft, and FIG. 4 is a cross-sectional view taken along the line IV--IV in FIG. 3. Screw rotor 1, metal shaft--2, combined Figure 1

Claims (1)

[Claims] In a screw rotor formed by injection molding a synthetic resin rotor onto a metal shaft so as to cover it, a lead angle of the rotor is formed on the surface of the portion of the metal shaft covered by the rotor. 1. A screw rotor characterized by having one or more grooves or protrusions carved therein having a lead angle opposite to the direction of.