CN108437401B - Full-smooth conical screw rotor of double-screw extruder - Google Patents

Abstract

The invention discloses a full-smooth conical screw rotor of a double-screw extruder, wherein the screw rotor is conical; the pitch P of the screw rotor is kept unchanged; from the suction end (I-I) to the discharge end (IX-IX) of the screw rotor) Tooth top arc radius R of section profile ₁ Gradually decrease, the radius R of the arc of the tooth root ₃ Gradually increasing; tip thickness delta of screw rotor ₁ And root thickness delta ₂ Is unchanged and equal along the axial direction all the time; the two screw rotors are identical and the axes are parallel; the full-smooth conical screw rotor of the double-screw extruder can effectively increase the working cavity volume of the suction end and reduce the working cavity volume of the discharge end, so that the screw rotor has a good extrusion function; the section molded lines of the screw rotors at any axial positions are completely and smoothly connected with adjacent composition curves, and the screw rotors generated by expanding the section molded lines along the spiral line can realize correct engagement, so that the friction and abrasion of the screw rotors are reduced, and the service life of the screw rotors is prolonged.

Description

A fully smooth conical screw rotor for a twin-screw extruder

technical field

The invention relates to a co-rotating twin-screw extruder, in particular to a fully smooth conical screw rotor suitable for the co-rotating twin-screw extruder.

Background technique

Twin-screw extruder is an important equipment in processing machinery. Because of its good feeding performance, mixing and plasticizing performance and exhaust performance, it has been widely used in the molding and processing of extruded products; co-rotating twin-screw extruders The extruder completes the conveying, plasticizing, mixing and kneading of the polymer through the synchronous double-rotation motion of the two screw rotors; the core component of the twin-screw extruder is a pair of intermeshing screw rotors. Form and meshing accuracy directly affect the quality of extruded products.

Patent CN107139424 discloses a fully smooth twin-screw extruder screw rotor. The cross-sectional profile of the screw rotor is composed of 6 sections of curves, and 4 sections of arcs are used to connect the addendum arc and the dedendum arc. The processing accuracy is high; the cross-sectional profiles of the two screw rotors are the same at any axial position, and the parallel twin-screw extruder with the screw rotor as the core component is limited by the center distance between the two screws. Small distance and poor load resistance.

Contents of the invention

In view of the above problems, and in order to enrich the types of screw rotors of twin-screw extruders, the present invention proposes a fully smooth conical screw rotor of twin-screw extruders: including left screw rotor (1) and right screw rotor (2) , the screw rotor is conical; the pitch P of the screw rotor remains unchanged; the composition curve type and number of the cross-sectional profile lines of the screw rotor at any axial position are the same; by keeping the central angle α of the addendum arc of the screw rotor constant, so that the screw rotor’s addendum thickness δ ₁ and dedendum thickness δ ₂ are always constant and equal; the left screw rotor (1) and the right screw rotor (2) are exactly the same, and the axes of the two screw rotors are parallel; the screw rotor The conical shape makes the screw rotor have good extrusion performance, and the two screw rotors rotate in the same direction, and there is a tangential effect at the meshing point, which effectively improves the mixing and dispersibility of the material, making the twin-screw extruder have dispersibility Good quality, high output and energy saving; at the same time, because the axes of the two screw rotors are parallel, the requirements for installation accuracy are greatly reduced; on the cross-sectional profile line at any axial position of the screw rotor, a section of eccentric circle involute and a section of eccentric The envelope curve of the circular involute smoothly connects the addendum arc and the dedendum arc, and the composition curve of the section profile is simple, which is convenient for processing and manufacturing; the section profile of the screw rotor is completely smooth and can realize completely correct The meshing reduces the friction and wear of the screw rotor and improves the service life of the screw rotor; the proposed fully smooth conical screw rotor of a twin-screw extruder is of great significance for improving the performance of the twin-screw extruder.

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

The invention proposes a fully smooth conical screw rotor for a twin-screw extruder, comprising a left screw rotor (1) and a right screw rotor (2), characterized in that: the left screw rotor (1) is conical, and the left screw rotor The pitch P of the rotor (1) remains constant; at any axial position, the composition curve type and number of the left section profile line (101) of the left screw rotor (1) are the same; from the suction end of the left screw rotor (1) From (Ⅰ-Ⅰ) to the discharge end (Ⅸ-Ⅸ), the addendum arc radius R ₁ of the left cross-sectional profile (101) of the left screw rotor (1) gradually decreases, and the dedendum arc radius R ₃ gradually increases , the pitch circle radius R ₂ remains unchanged; the addendum thickness δ ₁ and the dedendum thickness δ ₂ of the left screw rotor (1) are always constant and equal, that is, δ ₁ = δ ₂ ; the left screw rotor (1) and the right screw The rotors (2) are identical, and the axes of the two screw rotors are parallel;

The left section profile (101) of the left screw rotor (1) is composed of 4 curves: the left eccentric involute AB, the left dedendum arc BC, the conjugate curve CD of the left eccentric involute and the left addendum The arc DA is completely smooth connection between the adjacent composition curves; the right section profile (201) of the right screw rotor (2) is composed of 4 sections of curves: right eccentric circle involute ab, right dedendum arc bc, right The conjugate curve cd of the involute of the eccentric circle and the arc da of the right addendum; in the synchronous double-rotation motion in the same direction, the left screw rotor (1) and the right screw rotor (2) can achieve completely correct meshing; the left screw rotor The left sectional profile (101) of (1) and the right sectional profile (201) of the right screw rotor (2) can achieve correct meshing; the left eccentricity on the left sectional profile (101) of the left screw rotor (1) Circular involute AB, left dedendum arc BC, conjugate curve CD of left eccentric circle involute and left addendum arc DA are respectively connected with the right section profile line (201) of the right screw rotor (2) The conjugate curve cd of the involute of the right eccentric circle, the arc da of the right addendum, the involute ab of the right eccentric circle and the arc bc of the right dedendum can realize the correct meshing.

A fully smooth conical screw rotor of a twin-screw extruder, six geometric parameters on the left section profile (101) of the left screw rotor (1): addendum arc radius R ₁ , dedendum arc radius R _3. The radius R _b of the base circle of the involute of the eccentric circle, the central angle γ of the involute of the eccentric circle, the central angle α of the arc and the occurrence angle β of the involute of the eccentric circle satisfy the following equation:

In the formula: R ₂ is the pitch circle radius.

A completely smooth conical screw rotor of a twin-screw extruder, at any axial position, the radius of the addendum arc R ₁ and the arc of the dedendum on the left section profile (101) of the left screw rotor (1) The radius R ₃ changes with the change of the axial distance z from the section line to the suction end (I-I);

The relationship between the radius R ₁ of the addendum arc and the axial distance z is as follows:

The relationship between the root arc radius R ₃ and the axial distance z is as follows:

In the formula: R _s1 and R _d1 are the radius of the addendum arc at the suction end (I-I) and the discharge end (IX-IX) respectively; R _s3 and R _d3 are the suction end (I-I) and the discharge end respectively (Ⅸ-Ⅸ) the radius of the dedendum arc; z _m is the axial distance from the discharge end (Ⅸ-Ⅸ) to the suction end (Ⅰ-Ⅰ).

A fully smooth conical screw rotor of a twin-screw extruder, the equations of the curves of each segment on the left section profile line (101) of the left screw rotor (1) are as follows:

①Left eccentric circle involute AB:

②Left dedendum arc BC:

③Left addendum arc DA:

④The conjugate curve CD of the involute AB of the left eccentric circle:

Pick

角度，得到左偏心圆渐开线AB的包络线CD；Rotate the initial curve determined by the above equation clockwise around the rotation center point O

Angle, get the envelope CD of the involute AB of the left eccentric circle;

得到：make

get:

代入原始方程即得左偏心圆渐开线AB的共轭曲线CD的方程。will be solved

Substituting into the original equation, the equation of the conjugate curve CD of the left eccentric involute AB is obtained.

The beneficial effects of the present invention are:

①A fully smooth conical screw rotor of a twin-screw extruder is proposed. From the suction end (I-I) of the screw rotor to the discharge end (IX-IX), the cross-sectional profile of the screw rotor develops along the helical line At the same time, the addendum arc radius R ₁ of the cross-sectional profile of the screw rotor gradually decreases, and the dedendum arc radius R ₃ gradually increases, which can fully increase the volume of the working chamber at the suction end and reduce the volume of the working chamber at the discharge end, making the screw The rotor has a good extrusion function, which improves the extrusion efficiency of the twin-screw extruder;

② The axes of the proposed two screw rotors are parallel, which greatly reduces the requirements for installation accuracy;

③ The cross-sectional profile curve of the proposed screw rotor is simple and easy to process and manufacture;

④The cross-sectional profile of the proposed screw rotor is completely smooth connected between adjacent component curves, and the screw rotor generated by the cross-sectional profile of the screw rotor along the helical line can achieve completely correct meshing, which improves the force of the screw rotor The situation reduces the friction and wear of the screw rotor and improves the service life of the screw rotor;

⑤Enriched the screw rotor type of twin-screw extruder and the section profile type of screw rotor.

Description of drawings

Figure 1 is a cross-sectional line diagram of a fully smooth conical screw rotor of a twin-screw extruder.

Fig. 2 is an meshing diagram of cross-sectional profiles of two screw rotors.

Figure 3 is a diagram of a fully smooth conical screw rotor of a twin-screw extruder.

Figure 4 is the meshing diagram of two fully smooth conical screw rotors in operation.

Fig. 5 is an instantaneous meshing diagram of the section profiles of two screw rotors at (I-I) position;

Fig. 6 is the instant meshing diagram of the section profiles of two screw rotors at the (V-V) position;

Fig. 7 is an instantaneous meshing diagram of the cross-sectional profiles of the two screw rotors at the (IX-IX) position;

In the figure: R ₁ and R ₃ are respectively the addendum arc radius and the dedendum arc radius on the section profile of the screw rotor, R ₂ is the pitch circle radius, and 2R ₂ = R ₁ + R ₃ ; α is the addendum radius The central angle of the arc, the central angle of the dedendum arc is equal to the central angle of the addendum arc; β is the occurrence angle of the involute of the eccentric circle; R _b is the radius of the base circle of the involute of the eccentric circle; γ is The central angle of the involute of the eccentric circle; δ ₁ is the thickness of the addendum of the screw rotor; δ ₂ is the thickness of the dedendum of the screw rotor; P is the pitch of the screw rotor; 1 is the left screw rotor; 2 is the right screw rotor; 101 is The left section profile line of the left screw rotor (1); 201 is the right section profile line of the right screw rotor (2); points O and o are the center of rotation of the two screw rotor section profiles respectively, and the axes are respectively two The centerline of rotation of the two screw rotors; points N and n are the centers of the base circles of the eccentric involutes on the cross-sectional profile of the two screw rotors.

Detailed ways

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

As shown in Figure 1, it is the sectional profile diagram of the fully smooth conical screw rotor of the proposed twin-screw extruder; the left sectional profile (101) of the left screw rotor (1) is made up of 4 sections of curves, including two One-section arc and two sections of eccentric involute, counterclockwise as follows: left eccentric involute AB, left dedendum arc BC, conjugate curve CD of left eccentric involute and left addendum arc DA, complete smooth connection between adjacent composition curves; the shape of the left section profile (101) of the left screw rotor (1) is exactly the same as that of the right section profile (201) of the right screw rotor (2).

As shown in Figure 2, it is the meshing diagram of the section profiles of two screw rotors; the left section profile (101) of the left screw rotor (1) and the right section profile (201) of the right screw rotor (2) can realize Correct meshing; left eccentric involute AB, left dedendum arc BC, conjugate curve CD of left eccentric involute and left addendum on the left section profile (101) of the left screw rotor (1) Circular arc DA, respectively with the conjugate curve cd of the right eccentric circular involute on the right cross-sectional profile line (201) of the right screw rotor (2), the right addendum arc da, the right eccentric circular involute ab and the right The dedendum arc bc enables correct meshing.

As shown in Figure 3, it is a diagram of a fully smooth conical screw rotor of a twin-screw extruder; I-I and IX-IX are the axial positions corresponding to the suction end and discharge end of the two screw rotors respectively; the left screw rotor (1 ) from the left section profile (101) along the helical line from the suction end (I-I) to the discharge end (IX-IX). The addendum arc radius R ₁ gradually decreases, and the dedendum arc radius R ₃ gradually increases, making the screw rotor overall conical; the left screw rotor (1) and the right screw rotor (2) are identical, and the two The axes of the screw rotors are parallel;

As shown in Figure 4, it is the meshing diagram of two fully smooth conical screw rotors during operation; the pitch P of the screw rotor remains unchanged; the thickness of the addendum δ ₁ and the thickness of the dedendum δ ₂ of the screw rotor are always constant along the axial direction change and equal; in the process of developing the section profile along the helical line to generate the screw rotor, the axial distance z between the section profile and the suction end (I-I) is taken as 0, P/2, P, 3P/2, 2P, For 5P/2, 3P, 7P/2, 4P, the corresponding axial positions are respectively Ⅰ-Ⅰ, Ⅱ-Ⅱ, Ⅲ-Ⅲ, Ⅳ-Ⅳ, Ⅴ-Ⅴ, Ⅵ-Ⅵ, Ⅶ-Ⅶ, Ⅷ- VIII, IX-IX said.

As shown in Figure 5, it is an instantaneous meshing diagram of the cross-sectional profiles of the two screw rotors at the (I-I) position;

As shown in Figure 6, it is an instantaneous meshing diagram of the cross-sectional profiles of the two screw rotors at the (V-V) position;

As shown in Figure 7, it is an instantaneous meshing diagram of the cross-sectional profiles of the two screw rotors at the (Ⅸ-Ⅸ) position;

From Fig. 5, Fig. 6 and Fig. 7, it can be seen that the cross-sectional profiles of the two screw rotors are completely meshed at any axial position, so it can be explained that in the synchronous double-rotation motion in the same direction, the two screw rotors can achieve completely correct At the same time, it can be seen that from the suction end (I-I) to the discharge end (IX-IX) of the screw rotor, the addendum arc radius R ₁ of the cross-sectional profile line of the screw rotor gradually decreases, and the dedendum arc radius R ₃ gradually decreases. The pitch circle radius _R2 remains unchanged; the volume of the working chamber decreases gradually from the suction end (Ⅰ-Ⅰ) to the discharge end (Ⅸ-Ⅸ) of the two screw rotors generated by the section profile along the helical line , so that the screw rotor has a good extrusion function and improves the extrusion efficiency of the twin-screw extruder.

Although the specific implementation of the present invention has been described above in conjunction with the accompanying drawings, it is not a limitation to 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 (1)

1. A fully smooth conical screw rotor for a twin screw extruder, comprising: left screw rotor (1) and right screw rotor (2), characterized by: the left screw rotor (1) is conical, and the screw pitch P of the left screw rotor (1) is kept unchanged; the type and the number of the composition curves of the left section molded line (101) of the left screw rotor (1) at any axial position are the same; from the suction end (I-I) to the discharge end (IX-IX) of the left screw rotor (1), the tip arc radius R of the left section profile (101) of the left screw rotor (1) ₁ Gradually decrease, the radius R of the arc of the tooth root ₃ Gradually increase the pitch radius R ₂ Remain unchanged; tooth tip thickness delta of left screw rotor (1) ₁ And root thickness delta ₂ Is always unchanged and equal, i.e. delta ₁ ＝δ ₂ The method comprises the steps of carrying out a first treatment on the surface of the The left screw rotor (1) and the right screw rotor (2) are identical, and the axes of the two screw rotors are parallel;

the left section profile (101) of the left screw rotor (1) consists of 4 sections of curves: the left eccentric circle involute AB, the left tooth root arc BC, the conjugate curve CD of the left eccentric circle involute and the left tooth top arc DA are completely and smoothly connected with each other; the right section profile (201) of the right screw rotor (2) consists of 4 sections of curves: a right eccentric circle involute ab, a right tooth root arc bc, a conjugate curve cd of the right eccentric circle involute and a right tooth top arc da; in synchronous homodromous double-rotation motion, the left screw rotor (1) and the right screw rotor (2) can be completely and correctly meshed; the left section molded line (101) of the left screw rotor (1) and the right section molded line (201) of the right screw rotor (2) can be correctly meshed; the left eccentric involute AB, the left tooth root arc BC, the conjugate curve CD of the left eccentric involute and the left tooth top arc DA on the left section molded line (101) of the left screw rotor (1) are respectively meshed with the conjugate curve CD of the right eccentric involute, the right tooth top arc DA, the right eccentric involute AB and the right tooth root arc BC on the right section molded line (201) of the right screw rotor (2) accurately;

left section of left screw rotor (1)6 geometric parameters on the face line (101): radius R of tip arc ₁ Radius R of arc of tooth root ₃ Base radius R of involute of eccentric circle _b The following equations are satisfied between the central angle gamma of the involute of the eccentric circle, the central angle alpha of the circular arc and the occurrence angle beta of the involute of the eccentric circle:

wherein: r is R ₂ Is the pitch radius;

at any axial position, the tooth tip arc radius R on the left section line (101) of the left screw rotor (1) ₁ And root radius R ₃ As a function of the axial distance z of the section line from the suction end (I-I);

radius R of tip arc ₁ The relation of change along with the axial distance z is as follows:

radius of arc of tooth root R ₃ The relation of change along with the axial distance z is as follows:

wherein: r is R _s1 、R _d1 The radii of the tooth top circular arcs at the suction end (I-I) and the discharge end (IX-IX) respectively; r is R _s3 、R _d3 Root radius at the suction end (I-I) and the discharge end (IX-IX), respectively; z _m Is the axial distance from the discharge end (IX-IX) to the suction end (I-I);

the equation of each section of curve on the left section profile (101) of the left screw rotor (1) is as follows:

(1) left eccentric circle involute AB:

(2) left tooth root arc BC:

(3) left addendum arc DA:

(4) conjugate curve CD of left eccentric circle involute AB:

taking out

The initial curve determined by the equation is rotated clockwise around the rotation center point O

The angle is used for obtaining an envelope line CD of the left eccentric circle involute AB;

order the

The method comprises the following steps:

will be solved

Substituting the original equation to obtain the equation of the conjugate curve CD of the left eccentric circle involute AB.

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