JPWO2006090495A1 - Gear pump - Google Patents

Abstract

A gear pump suitable for transferring high-pressure, high-viscosity fluid such as molten resin is realized. In a gear pump 100 provided in the casing 1 for transferring fluid from the suction port 11 side to the discharge port 12 side by the rotation of the gears 2 and 3 meshing in pairs, the gears 2 and 3 are connected to each other with a one-point continuous contact tooth profile. For the gears 2 and 3, the ratio D / B of the gear outer diameter D to the tooth width B was set to 1.1 to 1.15. If D / B is less than 1.1, the bearing load may be excessive and damage to the bearing may occur, making it unsuitable for applications where molten resin or the like is pumped. On the other hand, if D / B exceeds 1.15, the mechanical efficiency is lowered and the overall efficiency is lowered along with the enlargement of the outer shape of the pump.

Description

The present invention relates to a gear pump used for transferring a high-pressure, high-viscosity fluid.

Many gear pumps that employ an involute tooth profile transfer fluid from the suction side to the discharge side by the rotation of the meshing gear. This is because the involute tooth profile is easy to cut and the measurement of the finish dimension of the tooth profile is easy, so that a highly accurate gear can be obtained, and therefore it can be adapted to high-pressure operation conditions.
Japanese Patent Laid-Open No. 11-013642

A problem of a gear pump that employs an involute tooth profile is a fluid confinement phenomenon. The meshing rate of the involute gear is usually greater than 1, and there is a period in which two sets of teeth are meshed. In that case, fluid is confined between these two sets of teeth, but the volume of the confinement region fluctuates as the gear rotates. Problems such as the generation of bubbles are brought about. However, the harm of the confinement phenomenon is much greater during compression than during expansion.

The harm of the above-mentioned confinement phenomenon becomes more prominent as the viscosity of the fluid to be transferred, the suction pressure, and the discharge pressure are higher. In particular, in applications where molten resin or the like is pumped, a fluid having a high temperature of about 300 ° C, a high pressure of about 20 MPaG, and a high viscosity of about 300 Pa · s is transferred, so that a large load is applied to the gear bearing due to the confinement phenomenon. , Bearing life is shortened. Currently, this is dealt with by improving the bearing, or by giving a margin to the bearing specifications (for example, increasing the shaft diameter, decreasing the rotational speed, etc.). It has been increasing.

The present invention made in view of the above is intended to realize a gear pump suitable for transferring a high-pressure, high-viscosity fluid such as a polymer or a molten resin.

In order to solve the above-described problems, a gear pump according to the present invention is provided in a casing having a suction port through which a fluid is introduced and a discharge port through which the fluid is discharged, and rotates in mesh with each other. And a pair of gears for transferring the fluid from the suction port to the discharge port, and the pair of gears is a one-point continuous contact tooth-shaped helical gear, and each gear has an outer diameter and a tooth width. The ratio is 1.1 to 1.15.

That is, a tooth profile such as an arc tooth profile, an elliptical tooth profile, or a sinusoidal tooth profile that always has one contact point and does not cause fluid confinement is used, and the axial thrust is balanced as a blind gear so that the axial thrust is applied to the gear. Avoid acting. In addition, by setting D / B to 1.1 to 1.15, the efficiency is ensured while suppressing the bearing load. If D / B is less than 1.1, the bearing load may be excessive and damage to the bearing may occur, making it unsuitable for applications where molten resin or the like is pumped. On the other hand, if D / B exceeds 1.15, the work that can be done for a large pump outer shape is reduced. The power loss due to the friction between the gear and the casing increases rapidly as the outer diameter of the gear increases, so reducing the tooth width and increasing the outer diameter for a given discharge amount increases the pump's outer diameter and increases mechanical efficiency. Directly linked to a decrease in overall efficiency. For the above reasons, it is desirable that D / B is 1.1 to 1.15.

According to the present invention, it is possible to realize a gear pump suitable for transferring a high-pressure, high-viscosity fluid such as a polymer or a molten resin.

The plane sectional view showing the gear pump of one embodiment of the present invention. FIG. 2 is a side sectional view of the gear pump shown in FIG. 1. The flowchart which shows the manufacture process of the molding of the high molecular weight polymer to which the gear pump of this invention is applied.

Explanation of symbols

1 ... casing by 2, the gear 100 ... gear pump 200 ... polymerizer 300 ... addendum of both gears forming apparatus 400 ... spinning device D ... gear outer diameter B ... tooth width E 3 _... rotate the inner circumferential surface of the casing Angle formed by the line segment connecting the two separated positions and the pitch points of the two gears E ₄ ... From the position where the tooth tip of the rotating gear is in close proximity to the inner peripheral surface of the casing, Arc angle to the position away from the surface

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

The gear pump 100 of the present embodiment shown in FIGS. 1 and 2 is a high-pressure material such as a molten resin or other high-molecular polymer at a high pressure in, for example, a petroleum plant, a chemical plant, a polymerization plant, a molding / spinning device, or the like. Used for pumping. These highly viscous materials may be intermediates or final products. The gear pump 100 is a so-called external gear pump, in which a drive gear 2 and a driven gear 3 are arranged in an internal space in which a casing 1 is enclosed, and the gears 2 and 3 are rotationally driven. This serves to pump the fluid captured in the tooth gap from the suction side to the discharge side. Actually, the suction side is positioned upward, the discharge side is positioned downward, a tank storing a polymer or molten resin is installed directly above the suction port 11, and the molten resin in the tank is sucked into the specified discharge. Discharge with pressure.

The drive gear 2 and the driven gear 3 are each a single-point continuous contact tooth-shaped helical gear. In the illustrated example, the tooth profiles of both gears 2 and 3 are arc teeth. For each gear 2, 3, the ratio D / B of the outer diameter D to the tooth width B is set between 1.1 and 1.15. This is because the gear pump 100 pumps a molten resin having a high temperature of about 300 ° C. at a high pressure of about 20 MPaG. Specific values of the gear outer diameter D and the tooth 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.

Therefore, the number of teeth Z and the twist angle (helical angle) β of the gears 2 and 3 are determined so that the ratio D / B between the gear outer diameter D and the tooth width B is within the range of 1.1 to 1.15. To do. If the tooth module is M and the pitch circle diameter is A,
A = MZ,
D = M (Z + 2)
Holds. In this embodiment, since the tooth profile of both the gears 2 and 3 is a one-point contact tooth profile, rotation is not transmitted unless it is twisted by 1 pitch in the gear shaft direction.
1 pitch = πA / Z = πM
And
B / 2 = πM / tan β
Need to be. If D / B = x, then
Z = (2πx / tan β) −2
It becomes.

Note that the twist angle β is preferably 32 ° or less in terms of the tooth profile processing step. From the above formula, if D / B = x is within the range of 1.1 to 1.15, the number of teeth is 10 to 12 when the twist angle β is set between 28 ° and 32 °. It becomes.

An arc gear pump having an arc tooth profile with M = 20, Z = 10, A = 200, β = 31 °, B = 209, and a capacity of 4189 cc / rev was manufactured and compared with a known involute gear pump. The involute gear pump used for performance comparison has M = 14, Z = 14, A = 200, β = 2.4 °, B = 209, and capacity 4080 cc / rev. The shaft diameter, bearing length, etc. related to performance were the same in both cases. At a liquid viscosity of about 300 Pa · s and a discharge pressure of 20 MPaG, the circular gear pump obtained the same performance as the involute gear pump. Further, although the constriction phenomenon does not theoretically occur in the arc tooth profile, when the discharge pressure pulsation is measured as an evaluation of confinement, it is 0.4% for the arc gear pump and 4% for the involute gear pump. All are values under the operating conditions of a liquid viscosity of about 300 Pa · s, a discharge pressure of 20 MPaG, and a rotation speed of 30 rpm. Although the discharge pressure pulsation changes depending on the measurement position and other measurement environments, the discharge pulsation of the circular gear pump is reduced to 1/10 compared to the involute gear pump.

By the way, as already described, the gear pump 100 of the present embodiment is mainly used for pumping a high-pressure, high-viscosity fluid. Therefore, the inner peripheral shape of the casing 1 is not formed so that the high-viscosity fluid can be sufficiently sucked into the tooth gaps of the gears 2 and 3 and the tooth tip leakage of the high-pressure fluid caught in the tooth gaps can be reduced. Must not. Hereinafter, a detailed description will be given with reference to FIG. Here, P ₁ and P ₁ are positions where the tooth tips of the rotating gears 2 and 3 start to approach the inner peripheral surface of the casing 1, and P _{2 is a} position where the tooth tips start to move away from the inner peripheral surface of the casing 1. , P ₂ , the pitch point of both gears 2, 3 is P ₀ , and the center of each gear 2, 3 is P _c , P _c .

The high viscosity fluids in order to guide smoothly in the tooth groove, the center P _c of the gears 2 and _3, a straight line passing through the P _c, the center P _c and sliding the starting point of the tooth tip P of gears 2 and 3 It is necessary to secure a size of about 0 ° to 6 ° in a side sectional view (a sectional view cut along a plane orthogonal to the gear axis) with respect to an angle E ₁ formed by a line segment connecting ₁ . However, the position of the sliding start point P _1, it is assumed that the center P _c of the gears 2 and _3, the straight line passing through the P _c is in the discharge side. Further, to reduce the tooth tip leakage, (centered on P _c) from sliding starting point P ₁ of the addendum to the sliding end point P ₂ for arc angle E _4, a sectional side view 72 ° or more It is preferable to ensure the size. As a guideline, the arc angle E ₄ is secured for at least two tooth spaces of the gears 2 and 3. Nevertheless, the flow path is narrowed in communication with the discharge port 12 by increasing the E _4, so could disturbed the discharge process fluid, E ₄ is suppressed to a size of up to about sectional side view 108 ° Should.

When E _{1 is set} to 0 ° or more and E _{4 is set} to 72 ° to 108 °, a line segment connecting the sliding contact start point P ₁ and the pitch point P ₀ is connected to the sliding contact end point P ₂ and the pitch point P ₀ . lines and the angle _{E 2} is a side cross-sectional view 33 ° -66 °. Therefore, the sliding end point _P 2, _{P 2} and the pitch point _{P 0} and the two line segments angle _{E 3} of connecting each of the gears 2 and 3, a side cross-sectional view 48 ° to 102 °. In other words, in order to secure required E ₁ and E ₂ (or E ₄ ), the upper limit of E ₃ needs to be about 102 °. Needless to say, the lower limit of E ₃ set to about 48 ° is to be flow down toward the smooth discharge port 12 to transfer fluid trapped in the tooth grooves.

According to the present embodiment, in the gear pump 100 that transfers the fluid from the suction side to the discharge side by the rotation of the gears 2 and 3 that mesh with each other, the gears 2 and 3 are helical gears having a one-point continuous contact tooth profile. In addition, since the ratio D / B of the gear outer diameter D to the tooth width B is set to 1.1 to 1.15 for each of the gears 2 and 3, adverse effects on the bearing due to the fluid confinement phenomenon can be avoided. . In addition, by setting D / B to 1.1 to 1.15, the efficiency can be ensured while suppressing the bearing load, and the pump external shape is not enlarged. The gear pump 100 according to the present embodiment is more suitable for transferring a high-pressure, high-viscosity fluid than a conventional involute gear pump.

Further, the angle _{E 3} 48 ° _~102 °, since the angle E4 ₄ and 72 ° -108 °, fluid can be sufficiently sucked into the tooth of the gear 2, and the teeth of the fluid captured in the tooth groove It is possible to reduce the leakage.

  The gear pump 100 of the present invention configured as described above is used in the process of manufacturing a polymer or molten resin, or a molded product from the polymer or molten resin. It can be applied to uses for producing a resin or a molded product.

For example, as shown in FIG. 3, the monomer is transferred from the monomer tank 110 to the polymerization tank 120 using the gear pump 100 of the present invention to produce a polymer, or the polymer is transferred to the gear pump 100. Then, it can be transferred to the molding apparatus 300 or the spinning apparatus 400 and used for the process of manufacturing the molded product. Further, even if a process for producing a high molecular weight polymer using the gear pump 100 of the present invention and a process for producing the molded product are integrated, a single production line as shown in FIG. 3 is constructed. Good. The monomer tank 110 and the polymerization tank 120 shown in FIG. 3 can be replaced with a resin pellet tank and a molten resin tank, respectively, to form a molten resin production line and a molded product production line.

Furthermore, the polymerization apparatus 200 can be formed by the monomer tank 110, the gear pump 100, and the polymerization tank 120 shown in FIG. Further, the molding device 300 or the spinning device 400 and the gear pump 100 may be separate from each other, or the molding device 300 or the spinning device 400 incorporating the gear pump 100 may be used.

The present invention is not limited to the embodiment described in detail above. The specific configuration of each part is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

This application claims priority based on Japanese Patent Application No. 2005-048965 filed on Feb. 24, 2005, and the contents of the application including the specification, drawings and claims of the application are all And include it here.

The gear pump of the present invention can be suitably used for, for example, an application for transferring a molten resin or other polymer polymer at a high pressure in a petroleum plant, a chemical plant, a polymerization plant, a molding / spinning apparatus, etc. The present invention can be used not only for transferring high-pressure and high-viscosity fluids.

Claims (16)

A casing having a suction port through which a fluid is introduced and a discharge port through which the fluid is discharged;
A pair of gears provided in the casing and meshing with each other to transfer the fluid from the suction port to the discharge port by rotation;
The pair of gears are one-point continuous contact tooth-shaped helical gears,
A gear pump characterized in that a ratio of an outer diameter and a tooth width of each gear 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 °.
In the inner peripheral shape of the casing,
An angle formed by a line segment connecting a position where each tooth tip of the rotating gear is separated from an inner peripheral surface of the casing and a pitch point of the gear is 48 ° to 102 ° in a side sectional view. The gear pump according to Item 1.
In the inner peripheral shape of the casing,
An angle formed by a line segment connecting a position where each tooth tip of the rotating gear is separated from an inner peripheral surface of the casing and a pitch point of the gear is 48 ° to 102 ° in a side sectional view. Item 3. The gear pump according to Item 2.
In the inner peripheral shape of the casing,
The arc angle from the position where the tooth tip of the rotating gear is in close proximity to the inner peripheral surface of the casing to the position where the tooth tip of the gear is separated from the inner peripheral surface of the casing is 72 ° to a side sectional view. The gear pump according to claim 1, wherein the gear pump is 108 °.
In the inner peripheral shape of the casing,
The arc angle from the position where the tooth tip of the rotating gear is in close proximity to the inner peripheral surface of the casing to the position where the tooth tip of the gear is separated from the inner peripheral surface of the casing is 72 ° to a side sectional view. The gear pump according to claim 2, wherein the gear pump is 108 °.
In the inner peripheral shape of the casing,
The arc angle from the position where the tooth tip of the rotating gear is in close proximity to the inner peripheral surface of the casing to the position where the tooth tip of the gear is separated from the inner peripheral surface of the casing is 72 ° to a side sectional view. The gear pump according to claim 3, wherein the gear pump is 108 °.
In the inner peripheral shape of the casing,
The arc angle from the position where the tooth tip of the rotating gear is in close proximity to the inner peripheral surface of the casing to the position where the tooth tip of the gear is separated from the inner peripheral surface of the casing is 72 ° to a side sectional view. The gear pump according to claim 4, wherein the gear pump is 108 °. The gear pump according to claim 1, wherein the gear pump according to claim 1 is used in the process of producing a polymer or molten resin, or producing a molded product from the polymer or molten resin. A method for producing a molded product. A gear polymer according to claim 2, wherein the gear pump is used in the process of producing a polymer or molten resin, or a molded product from the polymer or molten resin. A method for producing a molded product. A polymerization apparatus using the gear pump according to claim 1. A polymerization apparatus using the gear pump according to claim 2. A molding apparatus using the gear pump according to claim 1. A molding apparatus using the gear pump according to claim 2. A spinning device using the gear pump according to claim 1. A spinning device using the gear pump according to claim 2.

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