CN110242561A - A large-flow screw rotor of a twin-screw pump and its design method - Google Patents

Abstract

The invention discloses a large-flow screw rotor of a twin-screw pump and a design method thereof. The left end surface profile (101) of the left screw rotor (1) is composed of 4 sections of curves and 1 point: 1 section of short swing outward Line equidistant curve, 1 section of variable speed helix, 2 sections of circular arc, there is no sharp point in the profile; the right end surface profile (201) of the right screw rotor (2) is composed of 10 sections of curve: 2 sections of long outside Cycloid, 2-stage speed-changing spiral envelope, 6-stage arc, in the double-rotation motion in different directions with the transmission ratio of the left screw rotor (1) and the right screw rotor (2) being 2 to 1, the left end surface profile ( 101) can be correctly meshed with the right end surface molding line (201). Compared with the traditional screw rotor, the proposed high-flow screw rotor has a flow rate of 15% to 25% higher under the same casing size, which meets the flow requirements of miniaturized manufacturing. The structure is more compact, and the sealing and force performance are good.

Description

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

technical field

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

Background technique

The twin-screw pump is a positive displacement liquid pump. Two screw rotors meshing with each other form multiple closed cavities in the pump body. Driven by the gears, a pair of screw rotors make double-rotating motions in different directions in the pump cavity, sealing The cavity moves continuously from the inlet of the pump to the outlet of the pump, completing the process of suction, pressurization and discharge of the medium, and realizing the transportation of the liquid. 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, petrochemical industries, and food industries.

In the design and manufacture process of the screw pump, the design of the end surface profile of the screw rotor has a great influence on the performance of the pump. The commonly used twin-screw pump end profile is composed of cycloid and involute, and most of them are 1 to 1 transmission. In order to improve the performance of commonly used twin-screw rotors, a Chinese patent (patent number CN201720524780.9) proposes a fully smooth twin-screw pump screw rotor, which uses two arcs and its envelope to replace the commonly used point meshing pendulum Lines alleviate the wear problem at the sharp point, constitute a smooth connection between the curves, and the profile lines are completely and correctly meshed, which has the advantages of good sealing performance and good force characteristics, but it causes the problems of low volume utilization and low 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 occasions and have complex structures. How to meet the flow requirements and ensure good sealing and mechanical 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 to enrich the type of profile line on the end surface of the screw rotor of the twin-screw pump, the present invention proposes a high-flow screw rotor of the twin-screw pump. The radii of the top circle and the root circle of the two screws are equal, the transmission ratio of the left screw rotor and the right screw rotor is 2 to 1, and the flow rate is 15% to 25% higher than that of the original twin-screw pump under the same casing size. The structure is simpler and more compact than the original twin-screw pump. In the present invention, the speed-changing helix is used to smoothly connect the addendum arc and the dedendum arc in the profile line of the left end surface, and the conjugate curve of the speed-changing helix is obtained under the condition that the transmission ratio is 2 to 1, and the circular arc meshing short The equidistant curve of the epicycloid realizes the smooth connection of the addendum arc and the root arc on the right end surface profile line, and combines with the long epicycloid to form a symmetrical structure. The flow rate of the twin-screw pump is increased, the stress on the screw rotor is improved, and the performance of the twin-screw pump is improved.

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

A high-flow screw rotor of a twin-screw pump, including: a left screw rotor and a right screw rotor; the left end surface profile of the left screw rotor is composed of 4 sections of curves and 1 point, clockwise as follows: short swing outward Line equidistant curve AB, point B, addendum arc BC, shifting helix CD, dedendum arc DA; the shifting helix CD in the left end profile line smoothly connects addendum arc BC and dedendum Circular arc DA, there is no sharp point;

The right end profile of the right screw rotor is composed of 10 sections of curves, which are as follows in the counterclockwise direction: the first long epicycloid ab, the first dedendum arc bc, the first variable speed helix conjugate curve cd, the first Addendum arc de, first tooth tip arc ef, second long epicycloid fg, second dedendum arc gh, second variable speed helical conjugate curve hi, second addendum arc ij, second Two tip arcs ja; the right end profile line is centrosymmetric about its rotation center O ₂ , that is, the right end profile line coincides with itself after rotating 180° around the rotation center O ₂ .

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

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

1) The following parameters are given: left pitch circle radius R ₁ ; dedendum circle radius R ₂ ; addendum circle radius R ₃ ; speed change helix CD center angle θ; short epicycloid equidistant curve AB center angle α; 1. Tooth tip arc radius r; get the right pitch circle radius R ₄ , the first addendum circle radius R ₅ , and the first dedendum circle radius R ₆ according to the following relationship: R ₄ =2R ₁ ; R ₅ =R ₃ ; R ₆ =R ₂ ;

2) Establish a coordinate system with the center of rotation O1 _of the left screw rotor as the origin, and determine the dedendum arc DA according to the following equation:

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

3) Determine the addendum arc BC according to the following equation:

4) Determine the short epicycloid equidistant 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 epicycloid equidistant curve equation, L is the rotor center distance, L=R ₁ +R ₄ ;

5) Determine the variable speed helix CD according to the following equation:

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

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

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

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

9) Determine the first major 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 of the arc center of the tooth tip respectively;

11) The first long-width epicycloid ab, the first dedendum arc bc, the first speed change helix conjugate curve cd, the first addendum arc de, and the first addendum arc ef are respectively set as Rotate the center of rotation O ₂ by 180° to obtain the second long epicycloid fg, the second dedendum arc gh, the second gear shift helical conjugate curve hi, the second addendum arc ij, and the second addendum circle arc ja;

12) Axial helical expansion of the left end surface profile along the left helix to generate a left screw rotor; axial helical expansion of the obtained right end surface profile along a right helix to generate a right screw rotor; wherein the right screw rotor The pitch is twice the pitch of the left screw rotor.

The beneficial effects of the present invention are:

① The top circle and root circle radius of the two screws are equal, the transmission ratio of the left screw rotor and the right screw rotor is 2 to 1, and the flow rate is 15% higher than that of the original twin-screw pump with the transmission ratio of 1 to 1 under the same shell size ~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 miniaturized manufacturing under the premise of ensuring the flow rate.

②Adopt the meshing method of circular arc and short epicycloid equidistant curve, so that there is no sharp point in the end surface profile, which improves the mechanical characteristics of the screw rotor and increases the service life of the screw rotor.

③Enriched the types of profile lines on the end surface of the screw rotor of the twin-screw pump.

Description of drawings

Fig. 1 is the profile diagram of the left end surface of the left screw rotor (1).

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

Figure 3 is the meshing diagram of the two screw rotor end surface profiles.

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

Fig. 5 is a diagram of the meshing timing of the dedendum arc and the first addendum arc.

Fig. 6 is a diagram of the meshing timing of the short epicycloid equidistant curve and the first tooth tip circular arc.

Fig. 7 is a diagram of the meshing timing of the addendum arc and the first dedendum arc.

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

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

Figure 10 is a meshing diagram of two screw rotors.

In the figure: 1—left screw rotor; 2—right screw rotor; 101—left end profile; 201—right end profile; R ₁ —left pitch radius; R ₂ —radius of dedendum circle; R ₃ —addendum Circle radius; R ₄ —right pitch circle radius; R ₅ —first addendum circle radius; R ₆ —first dedendum circle radius; r—first tooth tip arc radius; α—short epicycloid equidistant Curve central angle; θ—central angle of variable speed helix; β—rotation angle.

Detailed ways

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

As shown in Figure 1, it is the profile line diagram of the left end surface of the left screw rotor 1. The profile line 101 of the left end surface of the left screw rotor 1 is composed of 4 sections of curves and 1 point, clockwise as follows: short epicycloid Equidistant curve AB, point B, addendum arc BC, shifting helix CD, dedendum arc DA; the shifting helix CD in the left end surface profile 101 smoothly connects addendum arc BC and dedendum Circular arc DA, there is no sharp point; the shape line is formed as follows:

1) The following parameters are given: left pitch circle radius R ₁ ; dedendum circle radius R ₂ ; addendum circle radius R ₃ ; speed change helix CD center angle θ; short epicycloid equidistant curve AB center angle α; 1. Tooth tip arc radius r; get the right pitch circle radius R ₄ , the first addendum circle radius R ₅ , and the first dedendum circle radius R ₆ according to the following relationship: R ₄ =2R ₁ ; R ₅ =R ₃ ; R ₆ =R ₂ ;

2) Establish a coordinate system with the center of rotation O1 of the left screw rotor ₁ as the origin, and determine the dedendum arc DA according to the following equation:

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

3) Determine the addendum arc BC according to the following equation:

4) Determine the short epicycloid equidistant 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 epicycloid equidistant curve equation, L is the rotor center distance, L=R ₁ +R ₄ ;

5) Determine the variable speed helix CD according to the following equation:

As shown in FIG. 2 , it is the profile diagram of the right end surface of the right screw rotor 2. The profile line 201 of the right end surface of the right screw rotor 2 is composed of 10 sections of curves, which are as follows in the counterclockwise direction: the first long epicycloid ab, The first dedendum arc bc, the first shifting helix conjugate curve cd, the first addendum arc de, the first tooth tip arc ef, the second long epicycloid fg, and the second dedendum arc gh , the conjugate curve hi of the second variable speed helix, the _second tooth tip arc ij, and the _second tooth tip arc ja; After the center rotates 180°, it coincides with itself; the forming method of the molded line is as follows:

1) The following parameters are given: left pitch circle radius R ₁ ; dedendum circle radius R ₂ ; addendum circle radius R ₃ ; speed change helix CD center angle θ; short epicycloid equidistant curve AB center angle α; 1. Tooth tip arc radius r; get the right pitch circle radius R ₄ , the first addendum circle radius R ₅ , and the first dedendum circle radius R ₆ according to the following relationship: R ₄ =2R ₁ ; R ₅ =R ₃ ; R ₆ =R ₂ ;

2) Establish a coordinate system with the center of rotation O2 of the right screw rotor ₂ as the origin, and determine the first dedendum arc bc according to the following equation:

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

4) Determine the conjugate curve cd of the first variable speed helix 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 of the arc center of the tooth tip respectively;

7) The first long-width epicycloid ab, the first dedendum arc bc, the first shift helix conjugate curve cd, the first addendum arc de, and the first addendum arc ef are respectively set as Rotate the center of rotation O ₂ by 180° to obtain the second long epicycloid fg, the second dedendum arc gh, the second gear shift helical conjugate curve hi, the second addendum arc ij, and the second addendum circle arc ja;

As shown in Figure 3, it is the meshing diagram of the end surface profiles of the two screw rotors. The left end surface profile line 101 and the right end surface profile line 201 are in the double-rotation motion of the left screw rotor 1 and the right screw rotor 2 with a transmission ratio of 2 to 1. It can realize correct meshing; the meshing relationship is: the point B of the left end surface profile line 101 meshes with the first long-width epicycloid ab and the second long-width epicycloid fg of the right end surface profile line 201; the left end surface profile line 101 The short-width epicycloid equidistant curve AB meshes with the first tooth tip arc ef and the second tooth tip arc ja of the right end surface profile line 201; the addendum arc BC of the left end surface profile line 101 meshes with the right end surface profile The first dedendum arc bc and the second dedendum arc gh of the line 201 mesh; the shifting helix CD of the left end profile 101 and the conjugate curve cd of the first shifting helix of the right end profile 201, the second The conjugate curve hi of the variable speed helix meshes; the dedendum arc DA of the left end profile 101 meshes with the first addendum arc de and the second addendum arc ij of the right end profile 201 .

As shown in FIG. 4 , it is a meshing time diagram between the speed change helix and the conjugate curve of the first speed change helix, and the speed change helix is correctly meshed with the conjugate curve of the first speed change helix.

As shown in FIG. 5 , it is a diagram of the meshing timing of the dedendum arc and the first addendum arc, and the dedendum arc and the first addendum arc are correctly meshed.

As shown in FIG. 6 , it is a diagram of the meshing timing between the short epicycloid equidistant curve and the first tooth tip arc, and the short epicycloid equidistant curve meshes correctly with the first tooth tip arc.

As shown in FIG. 7 , it is a diagram of the meshing timing of the addendum arc and the first dedendum arc, and the addendum arc and the first dedendum arc are correctly meshed.

As shown in FIG. 8 , it is a three-dimensional diagram of the left screw rotor 1 . The left screw rotor 1 is generated by axially spiraling the left end profile 101 along the left helix. The left screw rotor 1 is a single-head fixed-pitch screw.

As shown in FIG. 9 , it is a three-dimensional diagram of the right screw rotor 2, and the obtained right end surface profile 102 is axially helically expanded along the right helix to generate the right screw rotor 2, which is a double-ended fixed-pitch screw.

As shown in Figure 10, it is the 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 counter-rotating double-rotation movement with a transmission ratio of 2 to 1, and there is no interference or parts that do not participate in the meshing.

Although the specific implementation of the present invention has been described above in conjunction with the accompanying drawings, it does not limit the protection scope of the present invention. Those skilled in the art should understand that on the basis of the technical solution of the present invention, those skilled in the art do not need to pay creative work Various modifications or variations that can be made are still within the protection scope of the present invention.

Claims (3)

1. A high-flow screw rotor of a twin-screw pump, comprising: a left screw rotor (1) and a right screw rotor (2); it is characterized in that: the left end face molding line (101) of the left screw rotor (1) consists of 4 sections The curve is composed of a point, clockwise as follows: short epicycloid equidistant curve AB, point B, addendum arc BC, speed change helix CD, dedendum arc DA; the left end face type The variable speed helix CD in the line (101) smoothly connects the addendum arc BC and the dedendum arc DA, and there is no sharp point; The right end surface profile (201) of the right screw rotor (2) is composed of 10 sections of curves, which are as follows in the counterclockwise direction: the first long-width epicycloid ab, the first dedendum arc bc, and the first variable speed helix. Yoke curve cd, first addendum arc de, first addendum arc ef, second long epicycloid fg, second dedendum arc gh, second variable speed helix conjugate curve hi, second tooth The top arc ij, the second tooth tip arc ja; the right end surface profile line (201) is centrosymmetric about its rotation center _O2 , that is, the right end surface profile line (201) is rotated 180° around the rotation center _O2 and then coincide with itself. 2. The large-flow screw rotor of a twin-screw pump according to claim 1, characterized in that: the left end surface profile (101) and the right end surface profile (201) are located between the left screw rotor (1) and the right screw rotor (2) The correct meshing can be realized in the opposite direction double rotary movement with a transmission ratio of 2 to 1. The meshing relationship is: the point B of the left end surface profile (101) and the first long outside of the right end surface profile line (201) The cycloid ab and the second long epicycloid fg mesh; the short epicycloid equidistant curve AB of the left end surface profile (101) and the first tooth tip arc ef and the first tooth tip arc ef of the right end surface profile (201) The two tooth tip arcs ja mesh; the addendum arc BC of the left end surface profile (101) meshes with the first dedendum arc bc and the second dedendum arc gh of the right end surface profile (201); the left end The speed change helix CD of the surface profile (101) meshes with the first speed change helix conjugate curve cd and the second speed change helix conjugate hi of the right end surface profile (201); the left end surface profile (101) The dedendum arc DA meshes with the first addendum arc de and the second addendum arc ij of the right end profile (201). 3. A method for designing the large-flow screw rotor of the twin-screw pump as claimed in claim 1, characterized in that: comprising the following steps: 1) The following parameters are given: left pitch circle radius R ₁ ; dedendum circle radius R ₂ ; addendum circle radius R ₃ ; speed change helix CD center angle θ; short epicycloid equidistant curve AB center angle α; 1. Tooth tip arc radius r; get the right pitch circle radius R ₄ , the first addendum circle radius R ₅ , and the first dedendum circle radius R ₆ according to the following relationship: R ₄ =2R ₁ ; R ₅ =R ₃ ; R ₆ =R ₂ ; 2) Establish a coordinate system with the center of rotation O1 of the left screw rotor ( ₁ ) as the origin, and determine the dedendum arc DA according to the following equation: In the formula: t is the angle parameter, rad; 3) Determine the addendum arc BC according to the following equation: 4) Determine the short epicycloid equidistant 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 epicycloid equidistant curve equation, L is the rotor center distance, L=R ₁ +R ₄ ; 5) Determine the variable speed helix CD according to the following equation: 6) Establish a coordinate system with the center of rotation O2 of the right screw rotor ( ₂ ) as the origin, and determine the first dedendum arc bc according to the following equation: 7) Determine the first addendum arc de according to the following equation: 8) Determine the conjugate curve cd of the first variable speed helix according to the following equation: In the formula: is the first intermediate variable, determined by the following equation: 9) Determine the first major 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 of the arc center of the tooth tip respectively; 11) The first long-width epicycloid ab, the first dedendum arc bc, the first speed change helix conjugate curve cd, the first addendum arc de, and the first addendum arc ef are respectively set as Rotate the center of rotation O ₂ by 180° to obtain the second long epicycloid fg, the second dedendum arc gh, the second gear shift helical conjugate curve hi, the second addendum arc ij, and the second addendum circle arc ja; 12) Expand the left end surface profile (101) axially along the left helix to generate the left screw rotor (1); perform axial spiral expansion on the obtained right end surface profile (102) along the right helix to generate Right screw rotor (2); wherein the pitch of the right screw rotor (2) is 2 times of the pitch of the left screw rotor (1).