KR20070112211A - Gear pump - Google Patents

Abstract

A gear pump (100) suitable for feeding a high pressure and high viscosity fluid such as a molten resin, installed in a casing (1), and capable of feeding the fluid from a suction port (11) side to a discharge port (12) side by the rotation of gears (2) and (3) formed in a pair and meshing with each other. The gears (2) and (3) are formed in double helical gears with one-point continuous contact tooth profile and the ratios of the outer diameters D to the tooth widths B of the gears (2) and (3) are set to 1.1 to 1.15. When the ratio D/B is equal to or lower than 1.1, a bearing load is excessively increased and a bearing may be damaged. Therefore, the gear pump becomes unsuitable for feeding the molten resin. On the other hand, when the ratio D/B surpasses 1.15, a mechanical efficiency is lowered and, accordingly, the total efficiency is lowered according to an increase in the overall size of the pump.

Description

Gear Pump {GEAR PUMP}

The present invention relates to a gear pump. More specifically, it relates to a gear pump for conveying high pressure and high viscosity fluid.

In the gear pump which transfers a fluid from the suction side to the discharge side by rotation of the gear to engage, the involute gear form is quite many. Since the involute gear shape is easy to cut and the measurement of the gear-shaped finish dimension is also easy, a high precision gear can be obtained, and therefore, it is also suitable for high pressure operating conditions.

On the other hand, in the gear pump employing the involute gear form, there is a problem that the fluid trapping phenomenon occurs. Specifically, the engagement rate of the involute gear is more than one, and there is a period in which two sets of gears are engaged. In this case, the fluid is trapped between the two sets of gears. The volume of the area in which the fluid is trapped changes as the two sets of gears rotate. Therefore, when the volume is reduced, the trapped fluid is compressed to cause a waste of power due to an increase in pressure, and when the volume is increased, a part of the area in which the fluid is trapped becomes a vacuum or bubbles are generated inside the trapped fluid. To lower the mechanical efficiency.

Damage caused by fluid trapping is more severe when the trapped fluid is compressed than when it is expanded. In addition, the damage caused by the fluid trapping phenomenon is more pronounced the higher the viscosity, suction pressure and discharge pressure of the fluid to be conveyed.

In particular, when the gear pump is used for pumping molten resin, the molten resin is transported at a high temperature of about 300 degrees Celsius, a high pressure of about 20 MPa, and a high viscosity of about 300 Pascal seconds (Pa · s). do. When the fluid trapping phenomenon occurs in the gear pump under such high temperature, high pressure, and high viscosity, the gear bearing is subjected to a very large load, thereby shortening the bearing life.

In order to improve the above-mentioned problem, the bearing may be improved or the design parameters may be flexibly changed in the bearing design. For example, the bearing shaft diameter is increased or the bearing rotational speed is reduced to cope with the above problems, but the pump outline is enlarged and the driving force required is increased.

Therefore, the technical problem of the present invention is to solve such a conventional problem, the present invention provides a gear pump for efficiently transporting a high pressure and high viscosity fluid, such as molten polymer polymer or molten resin.

In order to solve the above problems, a gear pump according to an embodiment of the present invention is provided with a casing having an inlet port through which the fluid is introduced, a discharge port through which the fluid is discharged, and installed in the casing, are engaged with each other to rotate the fluid And a pair of gears for transferring from the suction port to the discharge port. The pair of gears may be a double helical gear in the form of a single point continuous contact gear, and the ratio D / B to the gear width B of each outer diameter D of the pair of gears is 1.1 to 1.15. It features.

The gears employed in the gear pump have a gear shape that always has one contact point and does not cause fluid trapping, such as arc shape gear shape, elliptical gear shape or sinusoidal gear shape and the like. The gear employed in the gear pump is a double helical gear, in which the axial thrust is balanced to prevent the axial thrust from acting on the gear.

Moreover, the said ratio D / B is set to 1.1-1.15, and the efficiency is ensured, restraining the load on a bearing. The said ratio D / B is less than 1.1, the load applied to a bearing may become excessive, and a damage may occur to a bearing, and a gear pump becomes unsuitable for the purpose of conveying molten resin etc. On the other hand, when the said ratio D / B exceeds 1.15, the gear pump external shape will become large and the work which can be done by it will become small. The power loss due to the friction between the gear and the casing increases rapidly with the increase in the outer diameter of the gear. Therefore, when gear width is made small and outer diameter is made large with respect to a fixed discharge amount, a gear pump external shape becomes large, mechanical efficiency falls, and overall efficiency falls. For the above reasons, the ratio (D / B) is preferably 1.1 to 1.15.

In order to solve the above problems, a gear pump according to another embodiment of the present invention is provided with a casing having an inlet port through which the fluid is introduced and a discharge port through which the fluid is discharged, and are installed in the casing to engage with each other to rotate the fluid. And a pair of gears for transferring from the suction port to the discharge port. The pair of gears may be a helical gear in the form of a single point continuous contact gear. The ratio D / B to the gear width B of the outer diameter D of each gear of the pair of gears is 1.1 to 1.15.

By adopting a pair of gears as a helical gear, the gears and the shift can be manufactured integrally, and the structure thereof is simple, thereby improving workability and productivity.

According to the gear pump according to the embodiment of the present invention, in the high pressure and high viscosity fluids such as molten polymer or molten resin, the loss caused by the fluid trapping phenomenon is suppressed and the efficiency decrease due to the enlargement of the device You can.

1 is a plan sectional view showing a gear pump according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view perpendicular to the axis of rotation of the gear pump shown in FIG. 1.

Figure 3 is a flow chart of the manufacturing process for producing a molded article of the polymer using the gear pump of the present invention.

4 is a plan sectional view showing a gear pump according to a second embodiment of the present invention.

FIG. 5 is a cross-sectional view perpendicular to the axis of rotation of the gear pump shown in FIG. 4.

<Description of the code>

1: casing 2, 3: gear

100 gear pump 200 polymerization apparatus

300: molding apparatus 400: spinning apparatus

D: Gear outer diameter B: Gear width

E ₃ : The angle at which the ends of both rotating gears form a line connecting two positions that are separated from the inner circumferential surface of the casing and the pitch points of both gears, respectively.

E ₄ : Circular arc angle from the position where the end of the rotating gear is close to the inner circumferential surface of the casing to the position where the end of the gear lies away from its inner circumferential surface.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. These examples are provided to more fully explain the present invention to those skilled in the art. Accordingly, in the drawings, the thicknesses of the devices and members are exaggerated or understated for clarity of the invention, and each device may further include various additional members not described herein.

Gear pump

[First Embodiment]

1 is a plan sectional view showing a gear pump according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view perpendicular to the axis of rotation of the gear pump shown in FIG. 1.

1 and 2, the gear pump 100, for example, in the petroleum plant, chemical plant, polymerization plant, molding, spinning apparatus, etc., pressurized high viscosity materials such as molten resin and other polymer polymers at high pressure Used to Their high viscosity can be intermediate or final product.

The gear pump 100 is a so-called external gear pump, and includes a drive gear 2 and a driven gear 3 arranged so as to engage with the inner space of the casing 1. As these drive gears 2 and driven gears 3 engage and rotate, the fluid caught in the grooves between the gears 2 and 3 is pumped from the suction side to the discharge side.

In one embodiment, the suction side is positioned above and the discharge side is positioned below, and a tank in which the polymer polymer and the molten resin are accumulated is provided immediately above the discharge port 11. The molten resin and the like in the tank may be sucked and discharged at a predetermined discharge pressure.

The drive gear 2 and the driven gear 3 may be double helical gears in the form of one point continuous contact gears. In FIG. 2, the drive gear 2 and the driven gear 3 have the form of an arc gear. The gear pump 100 pumps high temperature molten resin of about 300 ° C. at a high pressure of about 20 MPa. For each gear 2, 3, the ratio D / B to the gear width B of the outer diameter D is designed to have a value in the range of 1.1 to 1.15. The specific values of the gear outer diameter D and the gear width B are limited by the gear shaft diameter necessary for transmitting the rotational driving force to the gear and the shaft diameter necessary for suppressing the bending deformation of the gear shaft.

Then, the ratio (D / B) between the gear outer diameter (D) and the gear width (B) is within the range of 1.1 to 1.15, and the number of teeth Z and the torsion angle (helical angle) β of the gears 2 and 3 are determined. Decide If the gear module is M and the pitch circle diameter is A,

A = MZ

D = M (Z + 2)

The relation of is established. In the present embodiment, since the gear shapes of the drive gear 2 and the driven gear 3 are in the form of a one-point contact gear, rotation is not transmitted unless one pitch is twisted in the gear axial direction. therefore

1 pitch = πA / Z = πM

ego,

B / 2 = πM / tanβ

Need to be. If D / B = x, from above,

Z = (2πx / tanβ) -2

Becomes

Moreover, it is preferable that the torsion angle (beta) becomes 32 degrees or less on the gear-shaped process. In the above relations, if D / B = x falls within the range of 1.1 to 1.5, the number of teeth becomes 10 to 12 when the torsion angle β is set to a value between 28 and 32 degrees.

In this embodiment, when the gear of the gear pump adopts the circular gear shape, the parameters are circular arc gear pump such as M = 20, Z = 10, A = 200, β = 31 °, B = 209, capacity 4189cc / rev. Fabricated and compared to known involute gear pumps.

The involute gear pump used as a reference for performance has the following parameters: M = 14, Z = 14, A = 200, β = 2.4 °, B = 209, capacity 4080cc / rev. The shaft diameter, bearing length, etc. which were related to performance were made the same for both.

As a result of the performance, it was confirmed that at the liquid viscosity of about 300 Pa · s and the discharge pressure of 20 MPa, the arc gear pump showed the same performance as the involute gear pump. In addition, in the circular gear shape, fluid trapping does not occur in theory. However, when the discharge pressure wave was measured to observe the fluid trapping, about 0.4% of the circular gear pump and about 4% of the involute gear pump were observed. Both are values at the operating conditions of liquid viscosity of about 300 Pa · s, discharge pressure of 20 MPaG, and rotation speed of 30 rpm. The discharge pressure fluctuations change depending on the measurement position and other measurement environments, but the arc pressure gear pump reduces the discharge pressure fluctuations by 1/10 with respect to the involute gear pump.

However, as mentioned above, in this embodiment, the gear pump 100 mainly uses the high pressure and the high pressure | pressure feeding of the fluid. Therefore, the inner circumferential shape of the casing 1 should be formed so that the high viscosity fluid can be sufficiently sucked into the gear grooves of the gears 2 and 3 and the gear tip leakage of the high pressure fluid held in the gear grooves can be reduced.

After that, it will be described with reference to FIG. Here, the positions where the gear ends of the rotating gears 2 and 3 start to be in close proximity to the inner circumferential surface of the casing 1 are P ₁ , P ₁ , and the positions where the gear ends start to be separated from the inner circumferential surface of the casing 1. The pitch point of P ₂ , P ₂ , and both gears 2, 3 is P ₀ , and the center of each gear 2, 3 is Pc, Pc.

In order to smoothly draw high viscosity fluid into the gear groove, a straight line through the centers Pc and Pc of both gears 2 and 3, the center Pc of the gears 2 and 3 and the sliding start point of the gear tip ( About the angle (E ₁ ) formed by the line segments connecting P ₁ ), the size is about 0 ° to 6 ° (time of observing the cross section cut in the plane orthogonal to the axis of rotation of the gear). It is necessary to secure. However, it is assumed that the position of the sliding start point P ₁ is located on the discharge side rather than a straight line through the centers Pc and Pc of the two gears 2 and 3.

In addition, a gear to reduce the tip springs, the gear with respect to the from end sliding start point (P ₁₎ of the (with a focus on Pc) to the sliding end point (P ₂₎ angle subtended (E _4), the side end face of more than 72 ° It is desirable to secure the size.

The arc angle E ₄ aims to secure two or more gear grooves of the gears 2 and 3. Even so, when E ₄ is increased, the flow path communicating with the discharge port 12 is narrowed, which may cause a problem in the discharge process of the fluid. Therefore, E ₄ should be suppressed to about 108 ° in the side cross section.

When E ₁ is 0 ° or more and E ₄ is 72 ° to 108 °, the line segment connecting the sliding start point P ₁ and the pitch point P ₀ , the sliding end point P ₂ , and the pitch point ( The angle (E ₂ ) formed by the lines connecting P ₀ ) is 33 ° to 66 ° in the lateral section.

Therefore, the angle E ₃ formed by two line segments connecting the sliding end points P ₂ and P ₂ and the pitch point P ₀ to the two gears 2 and 3, respectively, is 48 ° to 102 ° in the side cross-section. do. Conversely, in order to secure required E ₁ , E ₂ (or E ₄ ), it is necessary to set the upper limit of E ₃ to about 102 °. Needless to say, the lower limit of E ₃ is set to about 48 ° to allow the fluid moved by the gear to flow toward the discharge port 12.

According to this embodiment, in the gear pump 100 which transfers a fluid from the suction side to the discharge side by rotation of the paired and engaged gears 2 and 3, the gears 2 and 3 are in one-point continuous contact. A double helical gear in the form of gears is used, and since the ratio D / B to the gear width B of the gear outer diameter D is set to 1.1 to 1.5 for each of the gears 2 and 3, the fluid is trapped. The bad influence to the bearing accompanying a phenomenon can be avoided.

In addition, by setting the ratio D / B to 1.1 to 1.15, efficiency can be ensured while suppressing the bearing load, and the pump outline does not have to be unnecessarily enlarged. In this embodiment, the gear pump 100, compared with the previous involute gear pump, it can be seen that the more suitable for the transfer of high pressure, high viscosity fluid.

In addition, since the angle E ₃ is set to 48 ° to 102 ° and the angle E ₄ is set to 72 ° to 108 °, the fluid can be sufficiently sucked into the gear grooves of the gears 2 and 3, and the gear groove It is possible to reduce the gear tip leakage of the fluid trapped in the.

The gear pump 100 of the present invention having the above configuration can be used in the production of a polymer polymer or molten resin, or in the process of producing a molded product from the polymer polymer or molten resin.

Figure 3 is a flow chart of the manufacturing process for producing a molded article of the polymer using the gear pump of the present invention.

Referring to FIG. 3, the gear pump 100 transfers monomers from the monomer tank 110 to the polymerization tank 120 using the gear pump 100 of the present invention, for example, and polymer polymers. It may be used in the process of manufacturing the, or the polymer polymer is transferred to the molding apparatus 300 or the spinning apparatus 400 via the gear pump 100, and the formation of the formation.

In addition, the process of manufacturing the polymer polymer using the gear pump 100 of this embodiment, and the process of manufacturing the molded article may be integrated, and a single manufacturing line as shown in FIG. 3 may be constructed. In addition, the monomer tank 110 and the polymerization tank 120 shown in FIG. 3 are substituted by the resin pellet tank and the melt resin tank, respectively, and can manufacture the molten resin and the manufacturing line of the molded object. It may be.

Moreover, it is also possible to form the polymerization apparatus 200 by the monomer tank 110, the gear pump 100, and the polymerization tank 120 shown in FIG. The molding apparatus 300 or the spinning apparatus 400 and the gear pump 100 may be separate bodies, or may be the molding apparatus 300 or the spinning apparatus 400 in which the gear pump 100 is formed.

Second Embodiment

4 is a plan sectional view showing a gear pump according to a second embodiment of the present invention. FIG. 5 is a cross-sectional view perpendicular to the axis of rotation of the gear pump shown in FIG. 4.

4 and 5, the gear pump 500, like the first embodiment, includes a drive gear 502 and a driven gear 503 disposed in an engaged state in the inner space of the casing 1. ). By rotationally driving these gears 502 and 503, a pump function for transferring the fluid captured in the gear grooves from the suction side to the discharge side can be provided.

The drive gear 502 and the driven gear 503 are helical gears in the form of one point continuous contact gear, respectively. In Fig. 5, both gears 502 and 503 are in the form of arc gears.

By the way, it is generally known that the gear pump 500 has a higher overall efficiency as the number of gears increases, the gear outer diameter is reduced, and the overall efficiency increases as the gear width increases. In addition, the bearing diameter necessary for transmitting the driving force and the bearing diameter from the deflection of the bearing due to the bearing load are limited, and the limits of the gear outer diameter and the gear width are determined from these elements. These limitations and limitations determine the optimum number of gears.

When the gear pump 500 is used for a high pressure of about 20 MPa, the ratio D / B of the gear outer diameter D to the gear width B is 1.1 to 1.15 as in the first embodiment.

And as in the first embodiment, if the gear outer diameter is D, the gear width is B, the gear module is M, the number of teeth is Z, the pitch radial diameter is A, and the torsion angle of the gear of the helical gear is β,

A = MZ,

D = M (Z + 2)

Becomes

Since the gear shape of both gears 502 and 503 is a one-point contact gear shape, rotation is not transmitted unless one pitch is twisted in the gear axial direction.

1 pitch = πA / Z = πM

And B = πM / tanβ.

If D / B = x, from above,

Z = (πx / tanβ) -2

Becomes

Β of the helical gear becomes 1/2 from β of the double helical gear, and β = 14 ° to 16 °. In the said double helical gear, it is preferable to set it as 32 degrees or less on the machining process of a gear form. In the case of a helical gear, even if β = 16 ° or more, there is no problem in the machining process of the gear shape.

When β = 18 °, Z = 9 when D / B = 1.1 and Z = 8 and D / B = 1.15.

Therefore, in the case of a helical gear, when Z = 8-12 and (beta) = 14 degrees-18 degrees, the effect similar to the above is acquired.

In the form of a circular gear, a helical gear pump with M = 32, Z = 10, A = 320, β = 16.75 °, B = 334.5 and a capacity of 17152 cm ³ / rev is constructed and compared with the known double helical pump of the circular gear type. It was.

The performance comparison is M = 32, Z = 10, A = 320, β = 31 °, B = 334.5, capacity 17152cm ³ / rev, in the double helical gear in the form of an arc. Naturally, the same is true except for the twist angle.

The same degree of performance was obtained even in an arc gear type helical gear under operating conditions of a liquid viscosity of about 300 Pa · s, a discharge pressure of 20 MPaG, and a rotation speed of 30 rpm.

In the helical gear pump in the form of an arc gear, even when the discharge pressure pulsation was measured as an evaluation of fluid trapping, the same result as 0.4% of the double helical gear pump was obtained. All are values at the operating conditions of liquid viscosity of about 300 Pa · s, discharge pressure of 20 MPaG, and rotation speed of 30 rpm. The difference from the known involute gear pump is clear from the results obtained with the same degree as the above result.

According to this second embodiment of the present invention, as described above, the same effect as in the first embodiment can be obtained, and furthermore, since the drive gear 502 and the driven gear 503 are helical gears, the gears and the shafts are separated. It can be produced integrally, and the workability and productivity are improved from the simple structure.

In the second embodiment, the gear pump 500 can be used to replace the gear pump 100 shown in FIG. 3, and the molding apparatus 300 or the spinning apparatus 400 in which the gear pump 500 is formed. May be configured.

This invention is not limited to embodiment mentioned above. The specific structure of each part is not limited to the said embodiment, A various deformation | transformation is possible in the range which does not deviate from the meaning of this invention.

This application claims priority based on Japanese Patent Application No. 2005-048965 for which it applied on February 24, 2005. The application content including the specification, drawing, and claim of this application is included here with reference to all. Let's do it.

Although the gear pump of this invention can be used suitably for the use which transfers molten resin and other high molecular weight polymers etc. in a petroleum plant, a chemical plant, a polymerization plant, a shaping | spinning apparatus, etc., it is not limited to these, for example. , So-called high pressure, high viscosity fluid can be used for the transfer.

Claims (32)

A casing having a suction port through which the fluid is introduced and a discharge port through which the fluid is discharged; And a pair of gears formed in the casing and engaged with each other to transfer the fluid from the suction port to the discharge port by rotation; The pair of gears is a double helical gear in the form of a single point continuous contact gear, A gear pump having a ratio between the outer diameter and the gear width of each of the gears is 1.1 to 1.15. The gear pump according to claim 1, wherein the number of teeth of each of the gears is 10 to 12, and the twist angle of each of the gears is 28 to 32 degrees. The inner peripheral shape of the casing according to claim 2, The angle formed by the position where each gear end of the rotating gear is separated from the inner circumferential surface of the casing and the line segment connecting the pitch point of the gear is 48 ° to 102 when the cross section perpendicular to the rotation axis of the gear is observed. It is a gear pump, characterized in that °. The inner peripheral shape of the casing according to claim 3, The arc angle from the position where the gear end of the rotating gear is close to the inner circumferential surface of the casing, and the position where the gear end of the gear deviates from the inner circumferential surface of the casing, observes a cross section perpendicular to the rotation axis of the gear. When the gear pump, characterized in that 72 ° ~ 108 °. The method of claim 2, In the inner circumference of the casing, The arc angle from the position where the gear end of the rotating gear is close to the inner circumferential surface of the casing, and the position where the gear end of the gear deviates from the inner circumferential surface of the casing, observes a cross section perpendicular to the rotation axis of the gear. When the gear pump, characterized in that 72 ° ~ 108 °. The inner peripheral shape of the casing according to claim 1, When the end of each gear end of the rotating gear is separated from the inner circumferential surface of the casing, and the angle formed by the line segment connecting the pitch point of the gear, the cross section perpendicular to the rotation axis of the gear is observed. Gear pump, characterized in that ° ~ 102 °. The inner peripheral shape of the casing according to claim 6, The arc angle from the position where the gear end of the rotating gear is close to the inner circumferential surface of the casing, and the position where the gear end of the gear deviates from the inner circumferential surface of the casing, observes a cross section perpendicular to the rotation axis of the gear. If the gear pump characterized in that 72 ° ~ 108 °. The inner peripheral shape of the casing according to claim 1, An arc angle from a position where the gear end of the rotating gear is close to the inner circumferential surface of the casing to a position where the gear end of the gear is separated from the inner circumferential surface of the casing is orthogonal to the rotation axis of the gear. Gear pump, characterized in that 72 ° ~ 108 ° when the cross section is observed. A method for producing a polymer polymer, a molten resin or a molded product, characterized in that the gear pump of claim 1 is used in the production of a polymer polymer or a molten resin or a molded product from a polymer polymer or a molten resin. A method for producing a polymer polymer, a molten resin or a molded product, characterized in that the gear pump of claim 2 is used in the production of a polymer polymer or a molten resin or a molded product from a polymer polymer or a molten resin. The polymerization apparatus using the gear pump of Claim 1. The polymerization apparatus using the gear pump of Claim 2. A molding apparatus using the gear pump according to claim 1. A molding apparatus using the gear pump according to claim 2. Spinning apparatus using the gear pump of Claim 1. Spinning apparatus using the gear pump of Claim 2. A casing having a suction port through which the fluid is introduced and a discharge port through which the fluid is discharged; And a pair of gears formed in the casing and engaged with each other to transfer the fluid from the suction port to the discharge port by rotation; The pair of gears is a helical gear in the form of a single point continuous contact gear, A gear pump, wherein the ratio between the outer diameter of each of the gears and the gear width is 1.1 to 1.15. The method of claim 17, The number of teeth of each of the gears is 8 to 12, the gear pump, characterized in that each twist angle of the gear is 14 ° ~ 18 °. The method of claim 18, In the inner circumferential shape of the casing, The angle formed by the position where each gear end of the rotating gear is separated from the inner circumferential surface of the casing and the line segment connecting the pitch point of the gear is 48 ° to 102 when the cross section perpendicular to the rotation axis of the gear is observed. Gear pump, characterized in that °. The method of claim 19, In the inner circumferential shape of the casing, The arc angle from the position where the gear end of the rotating gear is close to the inner circumferential surface of the casing, and the position where the gear end of the gear deviates from the inner circumferential surface of the casing, observes a cross section perpendicular to the rotation axis of the gear. When the gear pump, characterized in that 72 ° ~ 108 °. The method of claim 18, In the inner circumferential shape of the casing, The arc angle from the position where the gear end of the rotating gear is close to the inner circumferential surface of the casing, and the position where the gear end of the gear deviates from the inner circumferential surface of the casing, observes a cross section perpendicular to the rotation axis of the gear. When the gear pump, characterized in that 72 ° ~ 108 °. The method of claim 17, In the inner circumferential shape of the casing, The angle formed by the position where each gear end of the rotating gear is separated from the inner circumferential surface of the casing and the line segment connecting the pitch point of the gear is 48 ° to 102 when the cross section perpendicular to the rotation axis of the gear is observed. Gear pump, characterized in that °. The method of claim 22, In the inner circumferential shape of the casing, The arc angle from the position where the gear end of the rotating gear is close to the inner circumferential surface of the casing, and the position where the gear end of the gear deviates from the inner circumferential surface of the casing, observes a cross section perpendicular to the rotation axis of the gear. When the gear pump, characterized in that 72 ° ~ 108 °. The method of claim 17, In the inner circumferential shape of the casing, The arc angle from the position where the gear end of the rotating gear is close to the inner circumferential surface of the casing, and the position where the gear end of the gear deviates from the inner circumferential surface of the casing, observes a cross section perpendicular to the rotation axis of the gear. When the gear pump, characterized in that 72 ° ~ 108 °. A method for producing a polymer polymer, a molten resin or a molded product, characterized in that the gear pump of claim 17 is used in the production of a polymer polymer or a molten resin or a molded product from the polymer polymer or the molten resin. A method for producing a polymer polymer, a molten resin or a molded product, characterized in that the gear pump of claim 18 is used in the production of the polymer polymer or molten resin, or in the production of the molded product from the polymer polymer or the molten resin. The polymerization apparatus using the gear pump of Claim 17. The polymerization apparatus using the gear pump of Claim 18. A molding apparatus using the gear pump according to claim 17. A molding apparatus using the gear pump according to claim 18. Spinning apparatus using the gear pump of Claim 17. The spinning device using the gear pump of Claim 18.

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