CN110242561B - High-flow screw rotor of double-screw pump and design method thereof - Google Patents

Abstract

The invention discloses a large-flow screw rotor of a twin-screw pump and a design method thereof. The left end face profile line (101) of the left screw rotor (1) consists of 4 curves and 1 point: 1 short-width outward swing. Line equidistant curve, 1 section of variable speed spiral, 2 sections of arc, there is no sharp point in the profile; the right end profile (201) of the right screw rotor (2) is composed of 10 sections of curve: 2 sections of long outer Cycloid, 2-segment variable-speed helical envelope, 6-segment arc, in the opposite-direction double rotation motion of the left screw rotor (1) and the right screw rotor (2) with a transmission ratio of 2 to 1, the left end surface profile line ( 101) can mesh correctly with the right end face profile line (201). Compared with the traditional screw rotor, the proposed large-flow screw rotor has a flow rate increased by 15% to 25% under the same casing size, meeting the flow demand under miniaturization manufacturing, with a more compact structure and good sealing and stress performance.

Description

A large-flow screw rotor of a twin-screw pump and its design method

Technical field

The present invention relates to a twin-screw pump, and in particular to a large-flow screw rotor suitable for a twin-screw pump.

Background technique

The twin-screw pump is a positive displacement liquid pump. Multiple closed cavities are formed in the pump body through two intermeshing screw rotors. Driven by the gears, a pair of screw rotors perform birotational motion in opposite directions in the pump cavity to seal the The cavity continuously moves from the inlet of the pump to the outlet of the pump to complete the suction, pressurization and discharge process of the medium and realize the transportation of liquid. The twin-screw pump has the remarkable characteristics of no pulsation, small vibration, high reliability, good stability and strong self-priming ability. It is currently widely used in oil fields, shipbuilding industry, petrochemical industry, and food industry.

In the design and manufacturing process of screw pumps, the design of the end profile of the screw rotor has a great impact on the performance of the pump. The end profile of commonly used twin-screw pumps consists of cycloid and involute, and most of them are 1:1 transmission. In order to improve the performance of commonly used twin-screw rotors, Chinese patent (Patent No. CN201720524780.9) proposes a fully smooth twin-screw pump screw rotor, which uses two arcs and their envelopes to replace the commonly used point meshing pendulum. line, which alleviates the wear problem at the sharp points and forms a smooth connection between the curves. The profile lines mesh completely and correctly. It has the advantages of good sealing performance and good force characteristics, but it causes problems of low volume utilization and small flow rate. . With the development of society, the demand for small-sized screw pumps is increasing day by day. Traditional twin-screw pumps are mostly used in large flow situations and have complex structures. How to meet the flow requirements and ensure good sealing and stress performance during miniaturization has become the key to the problem.

Contents of the invention

In order to increase the flow rate of the twin-screw pump and at the same time enrich the end surface profile types of the screw rotor of the twin-screw pump, the present invention proposes a large-flow screw rotor of the twin-screw pump. The radii of the top and root circles of the two screws are equal, and the transmission ratio of the left screw rotor and the right screw rotor is 2 to 1. Under the same shell size, the flow rate is 15% to 25% higher than that of the original twin-screw pump. Under the same flow conditions The structure is simpler and more compact than the original twin-screw pump. The present invention uses a speed-changing spiral to smoothly connect the tooth tip arc and the tooth root arc in the left end face profile, and obtains the conjugate curve of the speed-changing spiral when the transmission ratio is 2 to 1, using arc meshing short The width epicycloid equidistant curve realizes the smooth connection of the tooth tip arc and the tooth root arc on the right end surface profile, and combines with the long width epicycloid to form a symmetrical structure. It increases the flow rate of the twin-screw pump, improves the stress on the screw rotor, and improves the performance of the twin-screw pump. It is of great significance to enrich the types of twin-screw pump screw rotor end surface profiles and improve its working performance.

In order to achieve the above objects, the present invention adopts the following technical solutions:

A large-flow screw rotor of a twin-screw pump, including: a left screw rotor and a right screw rotor; the left end face profile of the left screw rotor consists of 4 curves and 1 point, in order in the clockwise direction: short outward swing Line equidistant curve AB, point B, tooth top arc BC, speed change spiral CD, tooth root arc DA; the speed change spiral CD in the left end surface profile smoothly connects the tooth top arc BC and the tooth root. Arc DA has no sharp points;

The right end profile of the right screw rotor is composed of 10 curves, in order in the counterclockwise direction: the first long epicycloid ab, the first tooth root arc bc, the first speed change spiral conjugate curve cd, the first Tooth tip arc de, first tooth tip arc ef, second long epicycloid fg, second tooth root arc gh, second speed change spiral conjugate curve hi, second tooth tip arc ij, Two-tooth tip arc ja; the right end surface profile line is centrally symmetrical about its rotation center O ₂ , that is, the right end surface profile line is rotated 180° with the rotation center O ₂ as the center and then coincides with itself.

In the high-flow screw rotor of the twin-screw pump, the left end face profile and the right end face profile can achieve correct meshing in the opposite direction double rotation motion of the left screw rotor and the right screw rotor with a transmission ratio of 2 to 1, The meshing relationship is: point B of the left end face profile meshes with the first long epicycloid ab and the second long epicycloid fg of the right end face profile; the short epicycloid isometric curve of the left end face profile AB meshes with the first tooth tip arc ef and the second tooth tip arc ja of the right end face profile; the tooth tip arc BC of the left end face profile meshes with the first tooth root arc bc and the second tooth tip arc BC of the right end face profile. The two tooth root arcs gh mesh; the speed change spiral CD of the left end face profile meshes with the first speed change helix conjugate curve cd and the second speed change helix conjugate curve hi of the right end face profile; the left end face profile The tooth root arc DA meshes with the first tooth top arc de and the second tooth top arc ij of the right end face profile.

The design method of the large-flow screw rotor of a twin-screw pump includes the following steps:

1) Given the following parameters: left pitch circle radius R ₁ ; tooth root circle radius R ₂ ; tooth tip circle radius R ₃ ; center angle θ of the variable speed spiral CD; center angle α of the short-width epicycloidal equidistant curve AB; One tooth tip arc radius r; obtain the right pitch circle radius R ₄ , the first tooth tip circle radius R ₅ , and the first tooth root circle radius R ₆ according to the following relationships: R ₄ = 2R ₁ ; R ₅ = R ₃ ; R ₆ =R ₂ ;

2) Establish a coordinate system with the rotation center O ₁ of the left screw rotor as the origin, and determine the tooth root arc DA according to the following equation:

In the formula: t is the angle parameter, rad;

3) Determine the tooth tip arc BC according to the following equation:

4) Determine the short-amplitude epicycloid isometric curve AB according to the following equation:

in:

In the formula: M _AB is the rotation transformation matrix, β is the rotation angle, is the initial short-amplitude epicycloid isometric curve equation, L is the rotor center distance, L=R ₁ + R ₄ ;

5) Determine the speed change spiral CD according to the following equation:

6) Establish a coordinate system with the rotation center _O2 of the right screw rotor as the origin, and determine the first tooth root arc bc according to the following equation:

7) Determine the first tooth tip arc de according to the following equation:

8) Determine the first variable speed spiral conjugate curve cd according to the following equation:

In the formula: is the first intermediate variable, determined by the following equation:

9) Determine the first long epicycloid ab according to the following equation:

10) Determine the first tooth tip arc ef according to the following equation:

In the formula: X _ef and Y _ef are the abscissa and ordinate coordinates of the tooth tip arc center respectively;

11) Respectively combine the first long epicycloid ab, the first tooth root arc bc, the first speed change spiral conjugate curve cd, the first tooth tip arc de, and the first tooth tip arc ef to The rotation center O ₂ is rotated 180° to obtain the second long epicycloid fg, the second tooth root arc gh, the second speed change spiral conjugate curve hi, the second tooth tip arc ij, and the second tooth tip circle. Arc ja;

12) axially spirally unfold the left end face profile along the left spiral line to generate a left screw rotor; axially spirally unfold the obtained right end face profile along the right spiral line to generate a right screw rotor; where The pitch is twice the pitch of the left screw rotor.

The beneficial effects of the present invention are:

①The radii of the top and root circles of the two screws are equal. The transmission ratio of the left screw rotor and the right screw rotor is 2:1. Under the same shell size, the flow rate is 15% higher than that of the original twin-screw pump with a transmission ratio of 1:1. ~25%, the structure is simpler and more compact than the original twin-screw pump under the same flow rate, and it meets the needs of miniaturization manufacturing while ensuring the flow rate.

② The meshing method of arcs and short-width epicycloidal equidistant curves eliminates sharp points in the end surface profile, improves the force-bearing characteristics of the screw rotor, and increases the service life of the screw rotor.

③Enriched the end surface profile types of twin-screw pump screw rotors.

Description of the drawings

Figure 1 is a profile diagram of the left end face of the left screw rotor (1).

Figure 2 is a profile diagram of the right end face of the right screw rotor (2).

Figure 3 is a meshing diagram of the end profiles of the two screw rotors.

Figure 4 is a diagram of the meshing timing of the speed change helix and the first speed change helix conjugate curve.

Figure 5 is a diagram showing the meshing moment of the tooth root arc and the first tooth tip arc.

Figure 6 is a diagram showing the meshing moment between the short epicycloidal equidistant curve and the first tooth tip arc.

Figure 7 is a diagram showing the meshing moment of the tooth top arc and the first tooth root arc.

Figure 8 is a three-dimensional view of the left screw rotor (1).

Figure 9 is a three-dimensional view of the right screw rotor (2).

Figure 10 is the meshing diagram of the two screw rotors.

In the figure: 1—left screw rotor; 2—right screw rotor; 101—left end surface profile; 201—right end surface profile; R ₁ —left pitch circle radius; R ₂ —tooth root circle radius; R ₃ —tooth top Circle radius; R ₄ - right pitch circle radius; R ₅ - first tooth tip circle radius; R ₆ - first tooth root circle radius; r - first tooth tip arc radius; α - short amplitude epicycloid equidistant Curve center angle; θ—variable speed spiral center angle; β—rotation angle.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and examples.

As shown in Figure 1, it is the left end surface profile line diagram of the left screw rotor 1. The left end surface profile line 101 of the left screw rotor 1 consists of 4 curves and 1 point. In the clockwise direction, they are: short epicycloid Equidistant curve AB, point B, tooth top arc BC, speed change spiral CD, tooth root arc DA; the speed change spiral CD in the left end surface profile line 101 smoothly connects the tooth top arc BC and the tooth root. Arc DA has no sharp points; the shape line is formed as follows:

1) Given the following parameters: left pitch circle radius R ₁ ; tooth root circle radius R ₂ ; tooth tip circle radius R ₃ ; center angle θ of the variable speed spiral CD; center angle α of the short-width epicycloidal equidistant curve AB; One tooth tip arc radius r; obtain the right pitch circle radius R ₄ , the first tooth tip circle radius R ₅ , and the first tooth root circle radius R ₆ according to the following relationships: R ₄ = 2R ₁ ; R ₅ = R ₃ ; R ₆ =R ₂ ;

2) Establish a coordinate system with the rotation center O ₁ of the left screw rotor 1 as the origin, and determine the tooth root arc DA according to the following equation:

In the formula: t is the angle parameter, rad;

3) Determine the tooth tip arc BC according to the following equation:

4) Determine the short-amplitude epicycloid isometric curve AB according to the following equation:

in:

In the formula: M _AB is the rotation transformation matrix, β is the rotation angle, is the initial short-amplitude epicycloid isometric curve equation, L is the rotor center distance, L=R ₁ + R ₄ ;

5) Determine the speed change spiral CD according to the following equation:

As shown in Figure 2, it is a right end profile line diagram of the right screw rotor 2. The right end profile line 201 of the right screw rotor 2 is composed of 10 curves. In the counterclockwise direction, they are: the first long epicycloid ab, The first tooth root arc bc, the first speed change spiral conjugate curve cd, the first tooth tip arc de, the first tooth tip arc ef, the second long epicycloid fg, the second tooth root arc gh , the second speed change spiral conjugate curve hi, the second tooth tip arc ij, the second tooth tip arc ja; the right end surface profile line 201 is centrally symmetrical about its rotation center O ₂ , that is, the rotation center O ₂ is The center rotates 180° and then coincides with itself; the shape line is formed as follows:

1) Given the following parameters: left pitch circle radius R ₁ ; tooth root circle radius R ₂ ; tooth tip circle radius R ₃ ; center angle θ of the variable speed spiral CD; center angle α of the short-width epicycloidal equidistant curve AB; One tooth tip arc radius r; obtain the right pitch circle radius R ₄ , the first tooth tip circle radius R ₅ , and the first tooth root circle radius R ₆ according to the following relationships: R ₄ = 2R ₁ ; R ₅ = R ₃ ; R ₆ =R ₂ ;

2) Establish a coordinate system with the rotation center O ₂ of the right screw rotor 2 as the origin, and determine the first tooth root arc bc according to the following equation:

3) Determine the first tooth tip arc de according to the following equation:

4) Determine the first variable speed spiral conjugate curve cd according to the following equation:

In the formula: is the first intermediate variable, determined by the following equation:

5) Determine the first long epicycloid ab according to the following equation:

6) Determine the first tooth tip arc ef according to the following equation:

In the formula: X _ef and Y _ef are the abscissa and ordinate coordinates of the tooth tip arc center respectively;

7) Respectively combine the first long epicycloid ab, the first tooth root arc bc, the first speed change spiral conjugate curve cd, the first tooth tip arc de, and the first tooth tip arc ef to The rotation center O ₂ is rotated 180° to obtain the second long epicycloid fg, the second tooth root arc gh, the second speed change spiral conjugate curve hi, the second tooth tip arc ij, and the second tooth tip circle. Arc ja;

As shown in Figure 3, it is a meshing diagram of the end profile lines of two screw rotors. The left end profile line 101 and the right end face profile line 201 are in the opposite direction double rotation motion of the left screw rotor 1 and the right screw rotor 2 with a transmission ratio of 2 to 1. Correct meshing can be achieved; the meshing relationship is: point B of the left end face profile line 101 meshes with the first long epicycloid ab and the second long epicycloid fg of the right end face profile line 201; the left end face profile line 101 The short epicycloidal equidistant curve AB meshes with the first tooth tip arc ef and the second tooth tip arc ja of the right end face profile 201; the tooth tip arc BC of the left end face profile 101 meshes with the right end face profile The first tooth root arc bc and the second tooth root arc gh of the line 201 mesh; the speed change spiral CD of the left end face profile 101 and the first speed change helix conjugate curve cd and the second speed change helix of the right end face profile 201 The conjugate curve hi of the speed change spiral meshes with each other; the tooth root arc DA of the left end face profile 101 meshes with the first tooth addendum arc de and the second tooth addendum arc ij of the right end face profile 201.

As shown in Figure 4, it is the meshing time diagram of the conjugate curve of the speed change helix and the first speed change helix. The speed change helix and the conjugate curve of the first speed change helix mesh correctly.

As shown in Figure 5, it is the meshing time diagram of the tooth root arc and the first tooth top arc. The tooth root arc and the first tooth top arc mesh correctly.

As shown in Figure 6, it is a diagram of the meshing time between the short-width epicycloid equidistant curve and the first tooth tip arc. The short-width epicycloid equidistant curve meshes correctly with the first tooth tip arc.

As shown in Figure 7, it is the meshing time diagram of the tooth top arc and the first tooth root arc. The tooth top arc and the first tooth root arc mesh correctly.

As shown in Figure 8, which is a three-dimensional diagram of the left screw rotor 1, the left end surface profile line 101 is axially spirally expanded along the left spiral line to generate the left screw rotor 1. The left screw rotor 1 is a single-head fixed-pitch screw.

As shown in Figure 9, which is a three-dimensional diagram of the right screw rotor 2, the obtained right end surface profile line 102 is axially spirally expanded along the right spiral line to generate the right screw rotor 2. The right screw rotor 2 is a double-head fixed pitch screw.

As shown in Figure 10, it is a meshing diagram of two screw rotors, in which the pitch of the right screw rotor 2 is twice the pitch of the left screw rotor 1. The two screw rotors can achieve correct meshing in the opposite direction double rotation motion with a transmission ratio of 2:1, without interference or parts not participating in the meshing.

Although the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, they do not limit the scope of the present invention. Those skilled in the art should understand that based on the technical solutions of the present invention, those skilled in the art do not need to perform creative work. Various modifications or variations that can be made are still within the protection scope of the present invention.

Claims (3)

1. A large-flow screw rotor of a twin-screw pump, including: a left screw rotor (1) and a right screw rotor (2); characterized by: the left end face profile line (101) of the left screw rotor (1) consists of 4 segments The curve is composed of a point, and in the clockwise direction, they are: short epicycloidal equidistant curve AB, point B, tooth tip arc BC, speed change spiral CD, tooth root arc DA; the left end surface type The speed change spiral CD in line (101) smoothly connects the tooth tip arc BC and the tooth root arc DA, and there is no sharp point; The right end profile line (201) of the right screw rotor (2) is composed of 10 curves, in order in the counterclockwise direction: the first long epicycloid ab, the first tooth root arc bc, and the first speed change spiral. Yoke curve cd, first tooth tip arc de, first tooth tip arc ef, second long epicycloid fg, second tooth root arc gh, second speed change spiral conjugate curve hi, second tooth Top arc ij, second tooth tip arc ja; the right end face profile line (201) is centrally symmetrical about its rotation center O ₂ , that is, the right end face profile line (201) is rotated 180° with the rotation center O ₂ as the center. Then it coincides with itself. 2. A large-flow screw rotor of a twin-screw pump according to claim 1, characterized in that: the left end face profile line (101) and the right end face profile line (201) are in the left screw rotor (1) and the right screw rotor. (2) Correct meshing can be achieved in the opposite direction double rotation motion with a transmission ratio of 2 to 1. The meshing relationship is: point B of the left end face profile line (101) and the first long outer edge of the right end face profile line (201). The cycloid ab and the second long epicycloid fg mesh; the short epicycloidal equidistant curve AB of the left end surface profile (101) meshes with the first tooth tip arc ef and the second long epicycloid fg of the right end surface profile (201) The two tooth tip arcs ja mesh; the tooth tip arc BC of the left end face profile (101) meshes with the first tooth root arc bc and the second tooth root arc gh of the right end face profile (201); the left end The speed change spiral CD of the surface profile line (101) meshes with the first speed change spiral conjugate curve cd and the second speed change spiral conjugate curve hi of the right end surface profile line (201); the left end surface profile line (101) The tooth root arc DA meshes with the first tooth addendum arc de and the second tooth addendum arc ij of the right end surface profile line (201). 3. A method for designing a large-flow screw rotor of a twin-screw pump as claimed in claim 1, characterized by: comprising the following steps: 1) Given the following parameters: left pitch circle radius R ₁ ; tooth root circle radius R ₂ ; tooth tip circle radius R ₃ ; center angle θ of the variable speed spiral CD; center angle α of the short-width epicycloidal equidistant curve AB; One tooth tip arc radius r; obtain the right pitch circle radius R ₄ , the first tooth tip circle radius R ₅ , and the first tooth root circle radius R ₆ according to the following relationships: R ₄ = 2R ₁ ; R ₅ = R ₃ ; R ₆ =R ₂ ; 2) Establish a coordinate system with the rotation center O ₁ of the left screw rotor (1) as the origin, and determine the tooth root arc DA according to the following equation: In the formula: t is the angle parameter, rad; 3) Determine the tooth tip arc BC according to the following equation: 4) Determine the short-amplitude epicycloid isometric curve AB according to the following equation: in: In the formula: M _AB is the rotation transformation matrix, β is the rotation angle, is the initial short-amplitude epicycloid isometric curve equation, L is the rotor center distance, L=R ₁ + R ₄ ; 5) Determine the speed change spiral CD according to the following equation: 6) Establish a coordinate system with the rotation center O ₂ of the right screw rotor (2) as the origin, and determine the first tooth root arc bc according to the following equation: 7) Determine the first tooth tip arc de according to the following equation: 8) Determine the first variable speed spiral conjugate curve cd according to the following equation: In the formula: is the first intermediate variable, determined by the following equation: 9) Determine the first long epicycloid ab according to the following equation: 10) Determine the first tooth tip arc ef according to the following equation: In the formula: X _ef and Y _ef are the abscissa and ordinate coordinates of the tooth tip arc center respectively; 11) Respectively combine the first long epicycloid ab, the first tooth root arc bc, the first speed change spiral conjugate curve cd, the first tooth tip arc de, and the first tooth tip arc ef to The rotation center O ₂ is rotated 180° to obtain the second long epicycloid fg, the second tooth root arc gh, the second speed change spiral conjugate curve hi, the second tooth tip arc ij, and the second tooth tip circle. Arc ja; 12) axially spirally unfold the left end profile (101) along the left spiral line to generate a left screw rotor (1); axially spirally unfold the obtained right end profile (201) along the right spiral line to generate Right screw rotor (2); the pitch of the right screw rotor (2) is twice the pitch of the left screw rotor (1).