JP2588759B2 - Manufacturing method of screw rotor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing a screw rotor having twisted teeth used for a screw compressor, a screw pump, and the like.

(Prior Art) As a means for efficiently producing a screw rotor by plastic working, as described in JP-A-50-156013, a material having straight teeth is first extruded and then formed. How to form torsional teeth by applying torsional deformation to
As disclosed in Japanese Patent Application Laid-Open No. 62-63190, there is known a method in which a twist angle is provided in a tooth profile groove of a die, a material is extruded from the die, and a torsion tooth is formed by one processing.

(Problems to be Solved by the Invention) In a screw compressor, a pump, or the like, the torsion angle of the torsion tooth is determined by a required performance such as a compression ratio, and for example, a torsion angle of about 40 ° may be required.

However, the former of the prior art, the twist angle of 40 ° using a method of twisting a material having straight teeth.
When the machining is performed, there is a possibility that a uniform twist angle cannot be obtained over the entire length of the tooth due to a large amount of machining, or the twist angle of each tooth may not be uniform.

Also, in the latter method of forming with a die having a twist angle in the tooth groove, the resistance to extrusion in the tooth groove is large because the twist angle is large, and there is a possibility that a female rotor having a thin tooth profile may not have a tooth profile. Also, the mold wear is great.

It is therefore an object of the present invention to overcome these disadvantages of the prior art and to provide a means for easily producing an accurate rotor.

(Means for Solving the Problems) A means for solving the problems of the present invention includes a first step of extruding a toothed material from a die having a center hole and a plurality of tooth-shaped grooves extending radially from the center hole, A second step of applying a cold or hot twist to the toothed material, and a third step of extracting the twisted toothed material through a shaping die having a tooth profile groove having the same helix angle as the set helix angle of the rotor. A fourth step of coating the surface with a synthetic resin to which a lubricant has been added after drawing, and a fifth step of cutting the resin layer formed in the fourth step to form a uniform gap with a counterpart rotor. Become.

(Operation) In the first step, a toothed material having straight teeth or gently twisted teeth is extruded, and in the next second step, a torsional force is applied to both ends of the toothed material, which is close to the twist angle of the rotor. Or twisted to the same twist angle. By passing this material through a shaping die in a third step, a rotor having a set twist angle over the entire length is formed. Next, in the fourth step, a synthetic resin to which a lubricant is added is applied and dried to form a lubricating resin layer. If the gap with the counterpart rotor is not uniform or less than a predetermined value, the fifth step is a reduction. The resin layer is appropriately removed to form a constant gap.

(Example) Hereinafter, an example is described with reference to drawings. In FIG. 1, reference numeral 1 denotes a die for a first step of a female rotor, which is a combination of a male die 2 and a female die 3. Male dice 2
At the center, a mandrel 4 is connected by four arms 5, and passages 6, 6.
Has a slight protrusion from the end of the merging chamber 7. on the other hand,
The female die 3 has a central hole 8 followed by a radial tooth groove 9.
And the mandrel 4 enters the center hole 8 on the base end face 3a side. This female die 3 is not shown in FIG.
The configuration shown in FIG. The female die 3A shown in FIG. 2 (a) has no twist 5 extending radially from the center hole 8A.
When the material is extruded using this, a straight tooth 11A extending radially from the base 10A is formed as shown in FIG. 2 (b), and at the same time, the center is centered by the mandrel 4. with holes 12A are drilled tooth material W ₁ is formed.

On the other hand, the female die 3B shown in FIG.
E.g. 20 ° to the longitudinal direction
Are provided, and there is a phase difference e between the inlet side indicated by the dotted line, the solid line outlet side, and the solid line outlet side.

When this is used, as shown in FIG.
And helical teeth 11B having a twist angle of elongation α ₁ = 20 °, the toothed material W ₂ which Kokoroana 12B is formed at the center is formed from.

When a billet heated from an aluminum alloy is pressed into the die 1 shown in FIG. 1, the male die 2 is divided into four parts by the arms 5, 5,... And passes through the passages 6, 6,. , And are welded and integrated again and pushed into the female die 3. By making the male die 2 have such a structure,
The mandrel 4 can be shortened, so that the center hole does not shift due to runout. If the female die 3 is connected by attaching a mandrel to a long container without using such a male die 2, a large resistance to the billet occurs at the base end face 3a. It can be extruded with a small resistance.

Toothed materials W ₁ or W ₂ is made in the first step of the is added twist in the subsequent second step. In this second step, the toothed material is worked cold or hot at 200-250 ° C. Material W ₁ or W ₂ is gripped by the fourth view of the fixed chuck 14 and the roll chucks 15, arrows roll chuck 15 16
By twisting in the direction of, helical teeth 11 is formed with a twist of the tooth extending from the base portion 10, for example alpha ₂ = 40 °, Kokoroana 12 to the base 10 is toothed material W ₃ bored.

The toothed element W ₃ being error prone to twist angles, such as by non-uniform temperature distribution during heating, because the distortion is also caused in the chucking section, shaping process of the third step is performed in order to correct this . The shaping die 17 used for this processing is shown in FIG. 5, and the tooth space 18 is the female die shown in FIG. 3 (a).
The torsion angle is about twice that of 3B, and the phase difference between the front surface and the rear surface is 2e.

The shaping die 17 is fixed, grasping the tip chuck toothed material W ₃ obtained in the second step with you push, the variation in twist if but pulled a twist angle is corrected, FIG. 6 (a) ( female rotor W ₄ shown in b) is obtained.

Figure 7, with four round teeth in FIG. 8 is engaged with the male rotor to the female rotor W ₄ of each said. The male rotor W ₅ of FIG. 7, substantially have a semi-circular round teeth 19, 19 ... and Kokoroana 20, female die having a tooth space corresponding to the round teeth, using a chuck and shaping dies, the It is processed in the same procedure as the first, second and third steps.

Male rotor W ₆ of Figure 8 is substantially semi-circular and hollow helical teeth
Has 21, which was aimed at weight reduction by the hollow section 22, with using a longer container and the mandrel in place of the male die 2 in the first step in forming the male rotor W _6, enclose the mandrel 4 A plurality of molds are provided, and a semi-molten material or a highly heated billet is pressed and molded. The second and third steps are performed by the same means as described above.

Thus the female rotor W ₄ which is molded by the male rotor W ₅ or
The W _6, it is axially inserted fixed Kokoroana 12 and 20, in order to prevent the friction and noise generated by the rotor mating surface, in order to the synchronous rotation while maintaining a slight gap the male and female rotor Is fixed to the shaft.

However, it is difficult to achieve an accuracy with a constant gap over the entire helix, and partial contact may occur during operation. In order to reduce friction and noise generated in this case, at least one of the rotors is coated with an anti-friction resin layer as a fourth step. Figure 9 shows an example of forming a female rotor W ₄ in antifriction resin layer 23, the said resin layer 23, for example, polyimide as a base, polyamide, polyamideimide, epoxy, synthetic resins such as polyvinyl chloride are used , As lubricants, for example, Gr, MoS ₂ , WS ₂ , BN,
(CF) n, Sn powder, PTFE, etc. are added, and composite coating is performed to obtain a film thickness of 10 to 1000 μm. This film prevents contact between metals and improves sliding characteristics.

If the gap between the male and female rotors after coating with the anti-friction resin layer is not appropriate and uniform, as a fifth step, the surface layer of the anti-friction resin layer is cut with a hob or removed by grinding with a grindstone to correct it. Thus, a highly accurate screw rotor having wear resistance can be obtained.

(Effects of the Invention) The present invention combines the forming of the toothed material by extrusion in the first step, the torsion processing in the second step, and the drawing and shaping in the third step as described above, thereby making it impossible to process the material. , And the forming process is gradually added, so that a highly accurate rotor can be obtained. In addition, since the rotor is coated with the anti-friction resin layer in the fourth step and the resin layer is corrected in the fifth step so that the rotor gap is constant, both rotors come into contact with each other due to a rise in temperature during operation. Even in the state, the friction is small, and the generation of noise is prevented.

Therefore, when used for a compressor or a pump used in a place where the temperature is likely to be high, such as a supercharging compressor for an engine, a screw rotor that operates quietly, has no power loss, and has excellent effects such as high durability. Is obtained.

[Brief description of the drawings]

FIGS. 1 (a) and 1 (b) are a rear view and a longitudinal sectional view of a die used in a first step of the present invention, and FIG. 2 (a) is a front view of a female die for forming a straight toothed material. (B) is the product,
FIG. 3 (a) is a front view of a female die for forming a toothed material with twisted teeth, FIG. 3 (b) is the product thereof, FIG. 4 is an explanatory view of the second step, and FIG. FIGS. 6 (a) and 6 (b) are front and sectional views of a female rotor, and FIG.
8A and 8B are a front view and a sectional view of a male rotor, FIGS. 8A and 8B are a front view and a sectional view of another male rotor, and FIGS.
The figure is a sectional view of a rotor covered with a resin layer. 1 ...... die, 2 ...... male die 3, 3A, 3B ...... female die, 9, 9A, 9B ...... tooth groove 17 ...... shaping die, 23 ...... resin layer W _1, W _2, W ₃ ...... Toothed material W ₄ , W ₅ , W ₆ …… Rotor

Claims (2)

(57) [Claims] A first method for extruding a toothed material from a die having a center hole and a plurality of tooth grooves extending radially from the center hole.
And a second step of cold or hot torsion of the toothed material, and withdrawing the twisted toothed material through a shaping die having a toothed groove having the same helix angle as the set helix angle of the rotor. A third step, a fourth step of coating the surface with a synthetic resin to which a lubricant is added after drawing, and a fifth step of cutting the resin layer formed in the fourth step so as to form a uniform gap with a counterpart rotor. A method for manufacturing a screw rotor, comprising the steps of: 2. The screw rotor according to claim 1, wherein a twist is provided in the tooth profile groove of the die in the first step, and a toothed material having a helical tooth with a gentle helix angle is extruded. Method.