WO2004001229A1

WO2004001229A1 - Screw rotor

Info

Publication number: WO2004001229A1
Application number: PCT/JP2002/006295
Authority: WO
Inventors: Toshihiro Abe
Original assignee: Hokuetsu Industries Co., Ltd.
Priority date: 2002-06-24
Filing date: 2002-06-24
Publication date: 2003-12-31
Also published as: JPWO2004001229A1; CN1628216A; KR20050010753A; AU2002346203A1; CN100351522C; JP4271654B2

Abstract

A pair of screw rotors capable of eliminating interference between the blades thereof, providing excellent sealability, being rather easily machined, and minimizing produced blow holes, wherein the shapes of the cross sections of the pair of screw rotors in the direction perpendicular to the axis thereof are formed so that one (14) of square parts (14) and (15) formed between both ends (A) and (B) of a blade tip curve (13') and the blade side surface curves (18') and (19') thereof is formed so as to gradually reduce the radius of curvature toward the projected direction of the square part (14) in the shape of the cross section perpendicular to the axis, and the shape of the blade side surface curve (18') ranging from the square part (14) to a blade bottom surface curve (17') is formed in a curved line generated by the square part (14) formed in the other screw rotor.

Description

Description Scroll rotor Technical field

The present invention relates to a screw compressor for use in screw fluid machines such as screw compressors, vacuum pumps and other screw pumps, and more particularly to such a screw rotor. It relates to the tooth profile of the screw rotor. Technology background

In recent years, to improve the performance of screw compressors and vacuum pumps, a great deal of research has also been conducted on the tooth profile of screw compressors. There are a wide variety of data tooth shapes, including combinations of complex curves.

As shown in Fig. 10 (A), the tooth profile of such a screw rotor has a square shape in the axial cross section of the screw rotor, and has a flat shape. Both the tooth top surface 13 and the tooth bottom surface 17 are formed, and the tooth from the axial corners 14, 15 of the tooth top surface 13 to both ends 24, 25 of the tooth bottom surface is formed. As disclosed in Japanese Utility Model Laid-Open Publication No. 63-148884, a screw rotor 10 whose side surfaces 18 and 19 are formed so as to be orthogonal to the axis is disclosed. Has been.

As described above, in the screw rotor 10 disclosed in Japanese Unexamined Utility Model Publication No. 63-148488, which has a tooth shape with a rectangular cross section, the tooth tip has a surface (tooth surface 13). As a result, the seal formed between the inner surface of the cylinder and the tooth top surface 13 is a face seal and has high sealing performance. Fluid is compressed Leakage from the gap between the inner wall of the cylinder and the tooth surface of the screw rotor 10 to another working space located on the low pressure side can be suitably prevented, and the compression efficiency can be improved.

On the other hand, in the screw rotor 10 formed in this way, as shown in FIG. 10 (B), the tooth profile at the section perpendicular to the axis of the screw rotor is changed to the tooth tip surface. The tooth surface curve 1 3 ′ forming the contour of 13, the root surface curve 1 7 ′ forming the profile of the root 17, the tooth surface curve and the root surface curve are connected to connect the tooth surface 1. And a tooth side line 18 ′ having a contour of 8 is formed.The tooth side line 18 ′ is formed as a straight line extending in the outer peripheral direction of the screw rotor, and the tooth tip surface curved line 13 ′ is formed. A corner portion 14 formed between the tooth side surface line 18 'and the tooth side surface line 18' is formed substantially in a right angle.

When the two screw rotors 10a and 10b having such a tooth shape rotate synchronously, the corners of the two screw rotors 1Oa and 1Ob when the teeth mesh with each other. 14 interferes with the tooth side line 18 ′ formed on the other screw rotor. For this reason, the corners 14 of the screw rotor are cut out to prevent such interference (see FIG. 10 (C)).

However, when the screw rotors 10a and 10b are in the engaged state shown in FIG. 10 (B), for example, they are indicated by broken lines in FIG. 10 (B). If the corners 14 are notched, the sealing performance of the working space is reduced, and the screw rotors 10a and 10b are engaged with each other to form independent chambers. The working space A and the working space B communicate with each other due to this notch, and the compressed fluid leaks to the working space located on the low pressure side. Therefore, this type of screwer has a problem that the compression efficiency is reduced. In order to solve such a problem, Japanese Patent Publication No. S64-81193 discloses a screwer which exhibits good sealing performance while preventing tooth interference. There is a screener that has been disclosed (see Figure 11).

As shown in Fig. 11 (B), the shape of the tooth profile curve 18 'in the cross section perpendicular to the axis of the screwer is changed according to the screwer. Draw a point on the corner 14 that connects the tooth tip curve 13 'and the tooth side curve 18' of the other screw rotor combined with the screw rotor. It is formed so as to be able to achieve a substantially perfect seal by being formed by a curved curve.

Certainly, with the screwer disclosed in Japanese Patent Publication No. 6-81193, it is theoretically possible to achieve a substantially perfect seal, but this configuration of the screwdriver In order to ensure complete sealing in the retorator, the corners 14 must be formed in a convenient edge shape.

However, it is practically difficult to machine the corner portion 14 into a sharp edge shape. For example, such a screw rotor is manufactured by a cutting process. As a result, a large amount of burrs are formed on the corners 14, and when the corners are chamfered to remove the burrs, the chamfers cause a large amount of burrs. In both cases, since the edge shape of the corner portion 14 is cut away, the sealing property of the working space is reduced as in the case where the notch is provided.

Further, when the corner portion 14 is formed in an advantageous shape, the end portion 24 of the tooth bottom surface 17 formed in the other screwer where the corner portion 14 is formed has an advantageous shape. It must be machined, and the sharp parts of this tool are easily chipped, and even a slight chipping or abrasion will make it impossible to accurately cut the rotor. Frequent corrections Required.

Japanese Patent No. 290471,19 discloses a screw rotor in which the corners of a screw rotor in a cross section perpendicular to the axis are formed as arcs to improve the sealing performance. Is disclosed.

This screw rotor consists of the corners 14 of two screw rotors,

14 is formed by an arc, and the corner 14 forming the arc forms a tooth profile forming the tooth surface of the other screw rotor which is combined with the screw rotor concerned. .

In the screw rotor thus formed, no interference occurs between the two rotors, and the sealing property of the working space is improved.

However, since the corners 14 are formed as arcs as described above, when the corners of both rotors are located at the ridge line 33 of the inner wall of the cylinder and face each other, it is relatively difficult. A large blowhole is formed (see Fig. 12), and the adjacent working spaces communicate with each other via this blowhole, so that the compressed fluid is located in the working space located on the low-pressure side. It has the problem of leaking and lowering the compression efficiency.

Note that such leakage of the compressed fluid does not occur only at the corner portion 14 formed between the tooth tip surface 13 and the tooth side surface 18, but rather at the tooth tip. It also occurs in the gap between the surface 13 and the inner wall 31 of the cylinder.

A minimum clearance is required between the tooth tip surface 13 and the cylinder inner wall 31 to rotate the screw rotor, even if the screw fluid machine is operating. The inner diameter of the cylinder is set in consideration of the thermal expansion of the screw rotor so that the tooth tip surface 13 does not contact the inner wall 31 of the cylinder. However, the tip surface 13 of the screw rotor does not have a uniform thermal expansion amount with respect to the rotation axis, but has the highest thermal expansion amount. Since the inner diameter of the cylinder is set based on the location where the amount of tension is large, the gap between the tooth surface 13 and the inner wall 31 of the cylinder at the location other than the location where the thermal expansion is the largest If it is possible to provide a screw rotor having a structure that is large and easily leaks fluid through a gap in this portion, and that can suitably prevent leakage occurring in this portion, a vacuum pump is required. It is possible to further improve the working efficiency of the screw fluid machine such as the above.

Therefore, an object of the present invention is to solve the above-mentioned drawbacks in the prior art, there is no interference between the teeth of both screw rotors, the sealing property is good, and the processing is relatively easy. An object of the present invention is to provide a screw rotor having a tooth profile that is easy and can reduce the generated blowholes to a size that can be practically ignored. Disclosure of the invention

In order to achieve the above object, the screw rotor according to the present invention is formed by combining a pair of screw rotors 10a and 10b with the twisting directions reversed. In a screw rotor used for a screw machine that rotates, sucks and discharges a fluid,

The tooth profile of the pair of screw rotors 10 (1Oa, 1Ob) in the cross section perpendicular to the axis is the rotational axis O of the screw rotor 10 (10a, 10b). The tip surface curve 13 3 ′, which is composed of an arc of a predetermined diameter (r) centered at the center and which forms the contour of the tip surface 13, and the tip surface curve 1 concentric with the tip surface curve 13 ′ during the 3 'goodness Ri also small tooth bottom curve 1 7 forming an arc or RaNaru Ri contour of the tooth bottom 1 7 (r _2)' and 'the root surface curve 1 7' the tooth crest curve 1 3 Formed on the tooth side surface 18, "The two tooth side curves 18 ' With

One of the corners 14, 15 formed between both ends of the tip surface curve 13 ′ and the two tooth side curves 18 ′, 19 ′ is the tip surface curve Formed by a curve A-G connecting between one end A of 1 3 ′ and one end G of the tooth profile curve 18 ′,

The curve A—G connecting between one end A of the tip surface curve 13 ′ and one end G of the tooth side surface curve 18 ′ is changed from one end A of the tip surface curve 13 ′ to the corner portion. 14 has a shape in which the radius of curvature is gradually reduced in the protruding direction, and the tooth side surface curve 18 ′ extending from the corner portion 14 to the root surface curve 17 ′ is formed on the other screw rotor. One of the corners 14 and 15 is a curved line created by one of the corners 14 (see claim 1: see FIG. 6).

Further, in another screw rotor 10 (10a, 10b) of the present invention, a small number of parts are provided instead of the configuration of the above-described corner portion 14 or together with the configuration of the above-described corner portion 14 On the other hand, preferably, the tooth top surface curve 13 'of both screw rotors 10 (10a, 10b) is converted to the screw rotors 10 (1Oa, 10O). It is characterized in that it is formed in a range of 90 to 180 ° around the rotation axis of b) (claims 2 and 3).

The cross-section perpendicular to the axis of one of the corners 14, 15 can be constituted by a quadratic curve that is an ellipse, a parabola, or a hyperbola (claim 4). The corners 14 may be formed by a part thereof.

Further, the cross-sectional shape perpendicular to the axis of one of the corners 14 and 15 connects a plurality of points on a quadratic curve whose radius of curvature gradually decreases in the protruding direction of the corner 14. The quadratic curve formed thereby (Claim 6) Brief description of the drawings

1 is a sectional plane of a vacuum pump provided with the screw rotor of the present invention.

Fig. 2 is a front sectional view of Fig. 1.

FIG. 3 is a sectional view taken along the line III-III of FIG.

Fig. 4 is a sectional front view of the main part of the screw rotor.

Fig. 5 is a cross-sectional view of the screw rotor at right angles to the axis.

Figure 6 is an enlarged view of the corner of the screw rotor.

FIG. 7 is an explanatory diagram showing the relationship between the transverse width of the tooth tip surface in the axial direction and the length of formation of the tooth tip curve.

FIG. 8 is a schematic explanation showing a method for processing the screw rotor of the present invention.

9 is a schematic explanation showing a method for processing the screw rotor of the present invention. FIG. 10 shows a conventional screw rotor, (A) is a sectional view in the axial direction, and (B) is a corner portion. FIG. 4 is a cross-sectional view taken in a direction perpendicular to the axis showing an interference state, and FIG.

FIG. 11 shows another conventional screw rotor, in which (A) is a sectional view in the axial direction and (B) is an enlarged view of a corner portion in a sectional view perpendicular to the axis.

FIG. 12 is an explanatory view of blow holes formed in a conventional screw rotor. BEST MODE FOR CARRYING OUT THE INVENTION Next, the embodiment of the present invention will be described below with reference to the accompanying drawings. In the embodiment described below, an example is shown in which the scroller 10 of the present invention is used for the vacuum pump 1. The screwdriver 10 of the present invention is not only used as a screwdriver for the vacuum pump 1 but also for screw compressors and other screw pumps. It is applicable to screw fluid machines in general, such as Ryu pumps.

[Entire structure of vacuum pump]

In FIG. 1, reference numeral 1 denotes a configuration example of a vacuum pump provided with the screw rotor 10 (10a, 10b) of the present invention. The vacuum pump 1 of the present invention is rotatably accommodated in the casing 30 by two of the above-mentioned screw rotors 10 (10a, 10b). And then.

Inside the casing 30, there is a cylinder 31 that accommodates two scrolls 10a and 10b in a mated state. As the force is formed, it can be rotated by the rotor shaft 11 of each screw rotor 10a and 10b. \ Has been supported.

Of the screw rotors 10a and 10b, the rotor shaft 11 of the driving rotor 1Oa has a motor, engine, or other motor. The output shaft 41 of the drive source (motor 40 in this embodiment) is directly connected to the drive shaft, or through a speed reducer or other power transmission means. It is linked.

In this embodiment, the output shaft 41 of the motor 40 is connected directly to the rotor shaft 11 of the driving-side rotor 10a. As the motor 40 rotates, the driving-side rotor 10 a rotates with the rotation of the driving-side rotor 10 a, and the rotation of the driving-side rotor 10 a causes the rotation of the driving-side rotor 10 a. The driven-side rotor 10b that rotates with this rotates It is configured like this.

The synchronized rotation of the driven-side rotor 10a and the driven-side rotor 10b is performed by the rotor of each screw rotor 1Oa and 1Ob. This is performed by the combination of the timing gears 12 provided on the shaft 11, and the two screw rotors 10 a and 10 b have a very small interval. Are configured to work together.

On the outer wall of the casing 30 on which the above-mentioned cylinder 31 is formed, an inlet port 42 for introducing a fluid is provided at one end of the screwers 10a and 10b. And a discharge port 43 located at the other end side for discharging a fluid is formed so as to communicate with a space in the cylinder 31, and the drive-side screw rotor 10 is formed. When a is rotated, the driven-side screw rotor 1 Ob rotates in the opposite direction due to the combination of the timing gears 12, and the screw rollers 10 a and 10 0 are rotated. The fluid is introduced into the working space formed by the combination of b through the above-mentioned introduction port 42, and the introduced fluid is removed from the work space. The work space formed between the regulators 10a and 10b is transported toward the other ends of the screw regulators 10a and 10b. When it is done After being compressed is the product contraction, Ru is out ejection exit 4 3 good Ri ejection of the previous mentioned. ,

As shown in FIG. 3, the cylinder 31 for storing the scroller 10 (10a, 10b) has two screwers 1 as shown in FIG. In order to be able to accommodate 0a and 10b in a combined state, a cross-sectional shape of approximately 8 is formed, and the driving rotor 10a is accommodated. A ridgeline is formed at the boundary between the inner wall that forms the chamber that houses the inner wall and the inner wall that forms the chamber that houses the driven rotor 10b. ing .

In the embodiment shown in FIGS. 1 to 3, two screw screens having the same tooth shape are screwed in the same direction. Conversely, what is stored in the cylinder in a combined state is shown in the figure, but this screw rotor 10 (10a, 1 O b) may be different for each screw rotor 1 O a, 10 b, and they may be in a combined state. If it is rotatable, its shape is not limited to the illustrated example.

Similarly, in the illustrated example, only one screw is formed in each of the screwers 10a and 10b. As shown in the figure, each screw rotor 10a, 10b is a multi-rotor in which two or more screws are formed, and each screw rotor. The number of the rotors 10a and 10b may be different.

[Screen rotor]

As shown in FIG. 4, the screw rotor 10 of the present invention used for the vacuum pump 1 configured as described above has a spiral screw tooth shape as shown in FIG. It is formed with a lead angle.

As shown in FIG. 4, in the screw rotor of the present invention, one of the tooth side surfaces 18 and 19 in the cross section in the axial direction has one of the tooth surfaces 18 and 19, and the axial line X of the screw screw. It is formed in a curved shape that slightly depresses to the left in FIG. 4 with respect to a line Y that is orthogonal to the gear, and accordingly, the connection position between the tooth tip surface 13 and the tooth side surface 18 One of the corners 14, 15 corresponds to a slight angle in the axial section of the screw rotor 10, and the corner 14 forms the acute angle. The following tooth side surface 18 is overhanging from the root surface 17 toward the outer periphery.

The other corner 15 forms a slight obtuse angle in the axial cross section of the screw rotor 10, and the tooth side surface 19 following the corner 15 forms a tooth. An inclined surface that is inclined toward the bottom surface 17 is formed. The tooth profile of the screw rotor 10 formed in this manner in the cross section perpendicular to the axis of the screw rotor 10 is, as shown in FIG. 5, a tip surface composed of an arc having a radius centered on the screw rotor axis O. curve 1 3 ', around the axis O of the disk Li Interview low data, the tooth bottom curve 1 7 comprising a circular arc or we also Ri by an arc of small radius r ₂ of the tooth crest curve' and, the two curves The shape is substantially defined by the tooth side curves 18 'and 19' formed between and.

Of the aforementioned corners 14 and 15 formed between both ends of the tooth tip curve 13 'and the tooth side curves 18' and 19 ', the sharply formed corner 14 As shown by the solid line in FIG. 6, is formed by a curve A-G connecting one end A of the tooth tip surface curve 13 'to one end G of the tooth side surface curve 18'.

The curve A — G, which forms the cross section of the corner portion 14 at right angles to the axis, is a shape in which the radius of curvature gradually decreases from the end A of the tip surface curve 13 ′ toward the protrusion direction of the corner portion 14, for example, In the present embodiment, the top F ′ formed with the smallest radius of curvature is defined as a quadratic curve satisfying the condition, and one end of the long axis is defined as the top F ′. The cross section of the corner 14 is defined by a curve A-G composed of a part of the ellipse.

The shape of the corner portion 14 formed of the curves A to G is not limited to the above-mentioned ellipse, but may be in the direction in which the corner portion 14 protrudes from one end A of the tip surface curve 13 '. Any shape may be used as long as it becomes a curve whose shape gradually reduces the radius of curvature. In the above example, the quadratic curve, specifically, a part of the ellipse, is formed. The shape of the corner portion 14 is from the end A of the tip surface curve 13 'to the corner portion 14 from the end portion A. As long as the shape gradually reduces the radius of curvature in the protruding direction, the shape does not necessarily need to be symmetrical about the top F 'as in a quadratic curve. In the above-described example of the quadratic curve, in addition to the ellipse, for example, It may be composed of a curve obtained as an object line, a hyperbola, or a part thereof.

In addition, the curve forming the corner portion 14 does not need to accurately draw an ellipse or another quadratic curve, but takes a plurality of arbitrary points on this quadratic curve, and The shape is not limited to that of the embodiment, for example, is formed by connecting the curves by a smoothly connecting curve and forming a curve approximating a quadratic curve.

Thus, the corner portion 14 is changed into a curve whose curvature radius gradually decreases from the end A of the tip surface curve 13 ′ toward the projecting direction of the corner portion 14, especially such a quadratic curve. Due to the formation, the corners 14 are less likely to come into contact with the inner wall of the cylinder 31 even when the screw rotor 10 is thermally expanded. It is possible to make the gap St between the surface 13 and the inner wall of the cylinder 31 as small as possible.

Further, when compared with the conventional screw rotor 10 in which the cross section of the corner portion 14 at right angles to the axis is arc-shaped, the blowhole formed can be made as small as possible. .

At this point, the corners 14 as described above are formed into a cross-section perpendicular to the axis that gradually reduces the radius of curvature in the protruding direction, so that the tooth surface 13 and the inner wall of the cylinder 31 are formed. Referring to FIGS. 5 and 6, the point at which the gap between them can be narrowed will be described with reference to FIGS. 5 and 6. In consideration of the thermal expansion of the screw rotor due to the heat of compression of the fluid, this thermal expansion is applied between the tooth tip surface 13 of the screw rotor 10 and the inner wall of the cylinder 31. A gap δt is provided in consideration of the thermal expansion of the screw rotor 10 (see Fig. 6).

However, the gap St provided between the tooth tip surface 13 and the inner wall of the cylinder 31 becomes larger as the gap <5 t is increased. The gap 5 t should be as narrow as possible

During operation of the vacuum pump, the fluid in the working space generates heat due to the compression action, and the surface of the working space defined by the screw rotor is heated again by the fluid. The crawler thermally expands. At this time, the point of the largest thermal expansion in the screw rotor is the corner 14 that faces the working space and is located away from the axis of rotation. The curve A — G that forms part 14 has a shape in which the radius of curvature gradually decreases in the direction in which this corner protrudes, so that the curve from one end A of the tip surface curve 13, toward the tip. The shape gradually becomes farther from the inner wall of the cylinder 31 according to the above. Therefore, at the corners 14 that are susceptible to thermal expansion, there is a gap S t ′ in addition to the gap S.

Therefore, if it is possible to compensate for the increase in the amount of thermal expansion in the outer peripheral direction at the corner portion 14 in the gap δt ', the gap between the tooth tip surface 13 and the cylinder 31 inner wall can be compensated. Is the amount of deformation at the end A of the tip curve 13 '!リ As a result, the gap δt between the tooth tip surface 13 and the inner wall of the cylinder 31 can be reduced as much as possible.

On the other hand, as described in the prior art, when the cross section of the corner portion 14 at right angles to the axis is a circular arc, the corner portion 14 of the present scroller 10 is attached to the corner portion 14. In order to maintain the same length of protrusion as that shown in Fig. 6, as shown by the broken line in Fig. 6, the end of the tooth tip curve 1 3 'is It is necessary to extend to A ', the position on the tip side. Then, the gap St to be formed between the tooth tip surface 13 and the inner wall of the cylinder 31 needs to be determined in consideration of the thermal expansion amount in the outer peripheral direction at A ′.

However, the end A 'on the tip end side of the corner portion 14 in the protruding direction is located in the outer peripheral direction from the curve A-G, and is compared with the point A described above. Because the working space is close to the working space and is easily affected by the heat in the working space, the gap St determined based on the amount of deformation at the end A 'is inevitably wide in the large part of the thermal expansion. Become. From this, the inside diameter of the cylinder 31 is also increased, and the gap between the tip surface 13 other than the end A 'and the inner wall of the cylinder 31 is increased. And the fluid leaks.

On the other hand, similarly to the screw rotor 10 of the present application, the end of the tooth surface curve 13 ′ is defined as a point A in FIG. When the corner 14 is formed by an arc (dashed-dotted line in FIG. 6) in contact with the tooth surface curve 18 ′, the notch of the corner 14 becomes extremely large, and As a result, the blow rotor formed between the corners 14 and 14 of the screw rotors 10a and 10b becomes large, resulting in a screw rotor that cannot be put to practical use.

Thus, in the screw rotor 10 of the present invention, the gap St between the tooth tip surface 13 and the inner wall of the cylinder 31 can be reduced as much as possible. Thus, the sealing property is improved in this portion.However, in order to improve the sealing property between the tooth tip surface 13 and the inner wall of the cylinder 31, it is preferable to use the above-described configuration. Alternatively, or together with the above-described configuration, the tooth tip surface curve 13 ′ is set to 90 to 180 ° with respect to the entire outer circumference (360 °) around the rotation axis of the screw rotor 10. °.

Assuming that the tooth tip surface 13 of the tooth profile formed on the screw rotor 10 having the outermost circumference as the radius r is developed on a plane, this tooth tip surface 13 is It can be represented by a hypotenuse of a right-angled triangle A having a hypotenuse inclined at an angle, and a belt-like portion formed between straight lines parallel to the hypotenuse.

Here, when the above-mentioned band-shaped portion is wound around a cylinder, the lead of the helical winding formed by the hypotenuse of the right-angled triangle is denoted by R. The lead R of

R = 2π r tan a

And

The length of the tip surface curve 13 ′ in the range of 90 ° to 180 ° in the cross section perpendicular to the axis of the rotor is:

2 r _1/4 length of ≤ tooth crest curve ≤ Z [pi V 2 in the range between Do Ri, transverse width R of the tooth crest 1 3 in the axial direction of the disk Li Interview rotor 1 0 ',

7Γ r ≤ R '≤ 7Γ r _Λ ta a

That is, the transverse width R ′ of the tooth tip surface 13 in the axial direction is a length of 14 to 12 of the lead R.

In this way, the tooth profile of the tip surface 13 forming the tip surface 13 in the cross section perpendicular to the axis of the rotor has a shape that appears in the range of 90 ° to 180 °. In addition, the width of the tooth top surface 13 can be kept constant with respect to the lead length, and the sealing performance between the tooth top surface 13 and the inner wall of the cylinder is improved.

That is, the tip surface curve 13 ′ appearing in the section perpendicular to the axis is 90 ° or less with respect to the entire circumference (360 °) around the rotation axis of the screw rotor 10. In this case, the transverse width R ′ of the tooth tip surface 13 in the mouth axis direction is less than the length of the lead R 14, and the width of the tooth tip surface 13 is narrow. Sufficient sealing performance between the front surface 13 and the inner wall surface of the cylinder cannot be achieved. However, as described above, the tooth surface curves 13 and 90 are 90 ° to “!”. By forming it in the range of 80 °, it is possible to improve the sealing performance in this part, and when it is combined with the shape of the corner part 14 described above, the tip surface 13 In addition to the fact that the gap St between the inner wall of the cylinder 31 and the cylinder 31 can be made as small as possible, the screw using the screw rotor 10 can be used. Work efficiency Interview fluid machine be dramatically improved .

In FIG. 6, the tooth side surface curve 18 ′ connecting the curve A—G to the root surface curve 17 ′ (curve G—H in FIG. 6) is the tooth side surface 1 in the section perpendicular to the axis. The tooth side surface curve 18 ′ is formed by the above-mentioned shape that matches the screw rotor when both rotors are rotated synchronously. It is formed as a curve created by the curves A-G that form the corners 14 of the screw rotor.

As described above, the tooth profile curve 18 ′ is a curve created by the curve A—G that constitutes the corner 14 of the rotating screw rotor. When the working space is sealed between the corner 14 of the screw rotor and the tooth side 18 of the other screw mouth, the corner 14 of one screw rotor is Since the working space is sealed between any one of the positions of the curves A to G formed and the one of the tooth side surface curves 18 'of the other rotor, the sealing performance is good.

〔Production method〕

The above-mentioned screw rotor is cut by a rotating cutter as shown in FIGS. 8 and 9 as an example. In this cutting process, the axis 4 of the cutter rotating shaft 3 corresponds to the forming direction of the tooth groove having a predetermined torsion angle, that is, the rotating shaft of the work corresponding to the lead angle αί of the tooth profile. The cutter 7 is inclined at an angle α with respect to the core 7, and a single cutter is attached to the cutter rotating shaft 3 together with the spacer 2.

The cutter rotation center Oc of the single cutter is installed without the spacer 2 because the cutter rotation shaft 3 is provided with the spacer 2 having the length L. It is offset only to the right in the figure with respect to the cutter rotation center O c '. Therefore, the extension line in the moving direction of the center of rotation of the cutter is a predetermined distance It is set to pass through the shifted position li ;.

As described above, a method for manufacturing a screw cutter using a cutter with the center of rotation Oc set off is first described. First, along the cutter rotating shaft 3, Cut the single cutter that has been set to the right and move it to the workpiece 6 in the direction perpendicular to the rotating shaft core 7 of the workpiece 6 by the amount corresponding to the cut. After that, the single power cutter is rotated by the power rotary shaft 3. At that time, the workpiece 6 is waiting at the machining start position on the rotation axis 7 of the workpiece shaft 9 and on the left side of the single cutter.

Next, the work 6 is moved from the left side to the right side in the figure along the rotation axis while rotating the work 6 about the rotation axis 7.

When the peak reaches the end position, release the single cutter from the work force, and move the work along the work axis 9 to the left to the machining start position.

Next, the single force cutter is sent to the workpiece corresponding to the cutting amount in the orthogonal direction with respect to the rotary shaft core of the workpiece 6, and then the single cutter is moved to the cutter rotary axis. To rotate.

Next, the work 6 is moved from the left side to the right side in the figure along the rotary shaft while rotating the work 6 about the rotation axis 7.

When the work 6 reaches the end position of the stroke, release the single cutter from the work 6 once, and return the work 6 to the left side along the work axis 9 to the machining start position.

The above operation is repeated until the desired tooth profile is obtained, thereby adding the screw groove of the screw tooth profile.

By using a cutter with the center of rotation Oc offset, the single cutter is moved to the work side in accordance with the amount of cutting. At any time, since the axis of rotation of the shaft is not located on the extension of the direction of movement of the center of rotation of the cut, the tooth side surface 18, It is possible to machine the screw groove of the screw rotor with the inclined 19 without tilting the rotary axis of the cutter in the horizontal direction. In any case, the screw rotor 10 of the present invention is not limited to the processing by the above-described method, but is realized by a known processing apparatus in which the rotation axis of the cutter is inclined in the horizontal direction. It may be manufactured.

Since the screw rotor has a predetermined lead angle, if the portion for cutting the corner 14 of the cutter described above is formed in an arc shape having a predetermined diameter, the screw rotor has a predetermined angle. In the cross section, the shape of the corner portion 14 of the screwer 10 can be easily made to be an elliptical shape in which the radius of curvature gradually decreases in the direction in which the corner portion 14 protrudes. In addition, cutting blades that make the shape of the part that cuts the corner into an arc are relatively easy to manufacture and resharpening, and cutting tools that are formed in an arc shape are formed with an acute angle. Chipping and wear are less likely to occur compared to a cutting tool that has been used, and the tool has a long service life. Thus, the rotor can be cut accurately over a relatively long period of time. Furthermore, since the cutting edge having a circular arc shape at the corner cutting portion does not generate burrs due to cutting at the corner portion, the work of removing the burrs is not required, and The corners are not removed by the re-burring operation, and the sealability of the working space is not deteriorated. O According to the configuration of the present invention described above, the present invention In the case of the screw rotor having the tooth shape of the above, it is possible to obtain a complete seal line between the screw mouth and the screw. It was possible to make the profile as small as possible. As a result, we have been able to provide a scroller with improved sealability.

Also, make the gap between the tooth tip surface and the inner wall of the cylinder as narrow as possible.

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Claims

Scope of request A pair of screw rotors are rotated with their twisting directions reversed to rotate, and a screw rotor used in a screw machine that sucks and discharges a fluid has a blue color.

The tooth profile of each of the pair of screw rotors in a cross section perpendicular to the axis is formed by an arc of a predetermined diameter centered on the rotation axis of the screw rotor, and has a tooth top curve that forms the contour of the tooth top. And a root surface curve concentric with the root surface curve and having a smaller diameter than the root surface curve and forming a root surface contour; and a root surface curve formed between the root surface curve and the root surface curve. And two tooth side curves that form the contour of the tooth side

One of the corners formed between both ends of the tooth tip surface curve and the two tooth side surface curves is formed by a curve connecting one end of the tooth tip surface curve and one end of the tooth side surface curve. Forming

The curve connecting one end of the tip surface curve and one end of the tooth side surface curve is a curve that gradually decreases a radius of curvature from one end of the tip surface curve toward the direction in which the corner projects. A screw rotor characterized in that the tooth profile from the corner to the root surface curve is a curve created by one of the corners formed on the other screw rotor. —In a screw rotor used in a screw machine that sucks and discharges fluid by rotating by rotating the pair of screw rotors with the twisting directions reversed,

The cross section of each of the pair of screw rotors at right angles to the axis. The tooth profile is composed of an arc of a predetermined diameter centered on the rotation axis of the screw rotor, and a tip surface curve forming the contour of the tip surface, and a tooth surface curve concentric with the tip surface curve. A bottom surface curve formed of a small-diameter arc and forming a contour of a tooth bottom surface; and two tooth side surface curves forming a profile of a tooth side surface formed between the tooth tip surface curve and the root surface curve. The tooth surface curve from one of the corners formed between both ends of the tooth tip surface curve and the two tooth surface curves to the root surface curve is formed on the other screw rotor. With the curve created by one of the corners,

At least one of the screw rotors is characterized in that the tip surface curve is formed in a range of 90 to 180 ° around the rotation axis of the screw rotor. Screw rotor to be used.

3. In a screw rotor used for a screw machine that rotates by rotating a pair of screw rotors with their twisting directions reversed, and sucks and discharges fluid.

The tooth profile of each of the pair of screw rotors in a cross section perpendicular to the axis is formed by an arc of a predetermined diameter centered on the rotation axis of the screw rotor, and the tooth tip curve forming the contour of the tooth tip surface. And a root surface curve formed of a circular arc concentric with the root surface curve and having a smaller diameter than the root surface curve and forming a root surface contour; and formed between the root surface curve and the root surface curve. And two corners formed between both ends of the tip surface curve and the two tooth side curves, the tip curve. Formed by a curve connecting between one end of the tooth side curve and one end of the tooth profile.

Connect one end of the tooth tip curve and one end of the tooth side curve The curve is a curve in which the radius of curvature is gradually reduced from one end of the tooth tip surface curve toward the direction in which the corner protrudes, and the tooth side surface curve from the corner to the root surface curve is A curve formed by one of the corners formed in the screw rotor of the present invention, and

4. The screw rotor according to any one of claims 1 to 3, wherein a cross-sectional shape of one of the corners perpendicular to the axis is formed by a quadratic curve.

5. The screw rotor according to any one of claims 1 to 3, wherein one of the corners has a cross section perpendicular to the axis formed by a part of an ellipse.

6. The cross-sectional shape of one of the corners perpendicular to the axis is formed by connecting a plurality of points on a quadratic curve that gradually decreases the radius of curvature toward the direction in which the corners protrude. The screw rotor according to any one of claims 1 to 3, wherein the screw rotor is a curve approximating a quadratic curve.