JP3854058B2 - Gear pump - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a gear pump for conveying a highly viscous fluid such as a molten resin.
[0002]
[Prior art]
For example, a gear pump for transporting molten resin has a pair of gear rotors, and the gear rotor is rotatably supported by a pump body via a bearing. The bearing is a sliding bearing, and is a self-lubricating type in which a part of the molten resin to be conveyed is used as a bearing lubricant.
In this type of gear pump, it is important to increase the production amount (conveyance amount), and there are a method of increasing the rotation speed and a method of widening the tooth width. However, in any of the methods, the burden on the bearing is increased, and there is a high possibility that seizure will occur, and it is not easy to increase the production amount.
[0003]
That is, when the rotational speed is increased, the shear rate increases, so that the heat generated by the resin increases, the viscosity of the resin decreases, and the bearing support capacity decreases. Further, when the tooth width is increased, the load increases, and the bearing support capacity decreases.
Therefore, in this type of gear pump, it is most effective to improve the bearing capacity by lowering the temperature of the molten resin as a lubricant and increasing the viscosity of the resin.
As a method for cooling the lubricant (molten resin), a method for cooling the rotor shaft (for example, see Japanese Patent Publication No. 6-45135) and a method for cooling a bearing (for example, see Japanese Patent Application Laid-Open No. 9-217685), Alternatively, there is a combination of both (see, for example, JP-A-10-141247).
[0004]
[Problems to be solved by the invention]
Japanese Patent Laid-Open No. 9-21768 discloses a temperature control medium leak and a resin leak prevention by integrating a bearing and a visco seal.
However, since the bearing is fixed to the body, there is a problem that an excessive load is applied to the bearing.
That is, since the bearing is pressed in different directions depending on operating conditions such as discharge pressure and rotation speed (see, for example, JP-A-11-50973), it is preferable that the bearing is mounted in a free state with respect to the body. . However, fixing to the body as in the above prior art causes a problem that the bearing is forced.
[0005]
In particular, in the case of cooling the bearing, the clearance between the bearing and the body becomes larger due to the cooling of the bearing, and the above problem becomes more serious.
Further, the integrated type has a problem that it is difficult to manufacture and the cost is high.
On the other hand, in the one disclosed in Japanese Patent Laid-Open No. 10-141247, the bearing and the visco seal are configured as separate bodies, but there are problems that the cooling medium leaks and that the assembly is difficult.
[0006]
That is, the cooling medium inlet passage and the outlet passage to the bearing are provided in a cover (side plate) for fixing the bearing, and a seal structure between the cover and the bearing is difficult.
Accordingly, an object of the present invention is to provide a gear pump for conveying a high-viscosity liquid that maintains a bearing in a free state and improves reliability against leakage of a cooling medium or molten resin.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the present invention has taken the following measures.
That is, the present invention is characterized in that a pair of gear rotors are supported on a body of a gear pump via a bearing, and a cover for preventing the bearing from being pulled out in the axial direction is fixed to the body, and a temperature adjusting medium passage is connected to the bearing. In the gear pump, the inlet pipe and the outlet pipe to the temperature control medium passage are connected to the axial outer end face of the bearing, and the intermediate plate is interposed between the axial outer end face of the bearing and the cover. The intermediate plate is provided with insertion holes for the inlet pipe and the outlet pipe, and the cover is provided with a lead-out portion for loosely fitting the inlet pipe and the outlet pipe to guide it to the outside. It is in.
[0008]
In the present invention, the conventional problems can be solved by providing the intermediate plate.
The gear pump is preferably used for conveying a molten resin, and the bearing is preferably held in a non-fixed state with respect to the body and is lubricated by the molten resin.
It is preferable that the lead-out portion is recessed on the intermediate plate side end surface of the cover along the radial direction of the rotor.
It is preferable that both end surfaces of the intermediate plate are seal surfaces.
[0009]
Moreover, the both end surfaces of the said intermediate | middle plate can also be set as the structure contact | abutted to the said bearing and cover through the sealing member.
The inlet pipe and the outlet pipe are attached to the bearing via watertight means.
The intermediate plate can be constituted by a thrust plate provided for axial positioning of the bearing.
A visco seal for preventing liquid leakage from the gear rotor is provided at an axially outward position of the bearing, and the bisco seal is provided with a fastening means for increasing the mounting surface pressure between the intermediate plate and the cover. It is preferred that
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 and 2 show a gear pump for quantitative conveyance of molten resin in a kneading granulation system. This gear pump has a pump body 1 and a pair of gear rotors 2 housed in the body 1.
The body 1 is formed in a block shape, and a glasses-like rotor storage hole 3 is formed therethrough, and at the axially central portion and both radial sides of the rotor storage hole 3, A resin inlet 4 and an outlet 5 are formed. The pair of gear rotors 2 and 2 are rotatably accommodated in the rotor accommodating hole 3 via bearings 6.
[0011]
The rotor 2 includes a gear portion 7 and shaft portions 8 formed on both sides of the gear portion 7. The gear portions 7 of the pair of rotors 2 and 2 are always meshed, and the shaft portion 8 is supported by the bearing 6.
One end portion of the shaft portion 8 of the rotor 2 is connected to a drive device (not shown) via a coupling 9, and the rotor 2 is rotationally driven in the direction of arrow a in FIG. The molten resin is conveyed from the resin inlet 4 to the outlet 5.
The bearing 6 is fitted in the rotor housing hole 3 in an unfixed state. The bearing 6 is formed in a cylindrical shape, and an inner peripheral surface thereof is a sliding bearing surface, and a part of the outer peripheral surface is cut out to be a flat surface. When the bearing 6 is housed in the glasses-like rotor housing hole 3, the flat surfaces are brought into contact with each other to prevent its rotation. The outer diameter of the bearing 6 is large and is about 600 mm.
[0012]
The inner end surface in the axial direction of the bearing 6 can be brought into contact with the side surface of the gear portion 7 of the rotor 2. The axially outer end surface of the bearing 6 and the end surface of the body 1 are substantially flush.
The bearing 6 is prevented from slipping outward in the axial direction by a cover 11 attached to the end face of the body 1 via an intermediate plate 10. A small-diameter step portion is formed on the outer peripheral portion of the axially outer end portion of the bearing 6, and a ring-shaped thrust plate 12 is fitted to the step portion.
[0013]
The thrust plate 12 may be integrated with the bearing 6.
The intermediate plate 10 has a pair of through holes 13 for loosely fitting the shaft portion 8 of the gear rotor 2, and the outer shape thereof is large enough to cover the entire end surface of the bearing 6 and a part of the end surface of the body 1. And having a thickness of about 60 mm.
The cover 11 is a heavy object composed of blocks having an outer shape substantially the same as that of the intermediate plate 10 and a thickness of about 200 mm. The cover 11 is fixed to the end surface of the body 1 via bolts 14.
[0014]
The cover 11 is provided with a pair of seal member insertion holes 15 concentric with the shaft center of the gear rotor 2, and a visco seal 16 is fitted into the holes 15.
The visco seal 16 is formed in a cylindrical body with a flange, a flat surface is formed on a part of the outer peripheral surface thereof, and the pair of visco seals 16 are in contact with each other in the same manner as the bearing 6. Yes. The flange of the Bisco seal 16 is fixed to the cover 11 via a bolt 17. The axial inner end face of the visco seal 16 faces the outer end face of the intermediate plate 10. The inner peripheral surface of the visco seal 16 and the shaft portion 8 of the gear rotor 2 prevent the molten resin from flowing out by a labyrinth seal.
[0015]
A rotor temperature adjusting device 18 is provided at the axial center of the rotor 2, and a control device (not shown) for supplying a temperature adjusting medium to the adjusting device 18 is connected. Since the details thereof are the same as those described in Japanese Patent Publication No. 6-45135 and Japanese Patent Laid-Open No. 10-141247, the description thereof is incorporated and detailed description thereof is omitted.
The bearing 6 is also provided with a bearing temperature adjusting device 19, and a controller (not shown) for supplying a temperature adjusting medium is connected to the adjusting device 19. The bearing temperature adjusting device 19 has a temperature adjusting medium passage 20 formed inside the bearing 6. The temperature control medium passage 20 is configured by an annular space 21 formed in the bearing 6 and a partition wall 22 provided in the annular space 21.
[0016]
FIG. 3 is a developed view in the circumferential direction of the temperature control medium passage 20, and the partition wall 22 is provided in a spiral shape. By this partition wall 22, a temperature control medium passage 20 composed of two spiral grooves is formed in the annular space 21, a temperature control medium inlet 23 is formed at the end of one of the grooves, and the end of the other groove A temperature control medium outlet 24 is formed in the part.
As shown in FIG. 4, the bearing 6 is configured by integrally connecting an inner peripheral side member 6a and an outer peripheral side member 6b, and the temperature at the boundary between the inner peripheral side member 6a and the outer peripheral side member 6b. A conditioning medium passage 20 is formed.
[0017]
In this embodiment, an annular recess for forming the annular space 21 is formed on the outer peripheral surface of the inner peripheral member 6a, and a spiral partition wall 22 shown in FIG. 3 is integrally formed in the annular recess. ing. And the outer peripheral side member 6b is inserted in this inner peripheral side member 6a, and it integrates. Examples of this integration include welding and welding after shrink fitting.
In this integrated state, the outer peripheral surface of the partition wall 22 is in contact with the inner peripheral surface of the outer peripheral member 6b.
[0018]
Thus, when the partition wall 22 is formed between the inner and outer peripheral surfaces of the annular space 21, the partition wall 22 functions as a reinforcing member. Therefore, even if the annular space 21 is enlarged in order to enhance the cooling effect, the decrease in bearing strength can be reinforced.
In the present invention, an annular recess may be provided on the inner peripheral surface of the outer peripheral member 6b, and the partition wall 22 may be provided in the recess. Further, the temperature control medium passage 20 is not limited to a double spiral groove structure, and may be a groove structure formed by a combination of a circumferential partition wall and an axial partition wall. The thing of the meandering hole as described in 217865 gazette may be used.
[0019]
The temperature control medium inlet 23 and outlet 24 are drilled from the outer peripheral surface of the bearing 6 toward the annular space 21 and from the outer end surface of the bearing 6 toward the radial hole. The axial hole 26 is provided. The outer end of the radial hole 25 is sealed with a stopper 27.
An inlet pipe 28 and an outlet pipe 29 are joined to the outer end face in the axial direction of the bearing 6. One end portions of the inlet pipe 28 and the outlet pipe 29 are joined to the axial hole 26 through a watertight means 30 so that no liquid leakage occurs.
[0020]
In this embodiment, welding is adopted as the watertight means 30. However, the watertight means 30 is not limited to welding, and prevents liquid leakage by screwing and using an adhesive or sealant. Also good.
The thrust plate 12 and the intermediate plate 10 are provided with an insertion hole 31 concentrically with the axial hole 26. The inlet pipe 28 or the outlet pipe 29 is inserted into the insertion hole 31 in a loose fit.
As shown in FIG. 5, the cover 11 is provided with a lead-out portion 32 that loosely fits the inlet pipe 28 and the outlet pipe 29 and guides them to the outside. The lead-out portion 32 is formed by a U-shaped concave portion that is recessed along the radial direction of the rotor 2 on the intermediate plate side end surface of the cover 11.
[0021]
At least a part of the inlet pipe 28 and the outlet pipe 29 is constituted by a flexible tube and is bendable. Therefore, the inlet pipe 28 and the outlet pipe 29 extending outward in the axial direction from the end face of the bearing 6 are bent at right angles after exiting the insertion hole 31 of the intermediate plate 10, and the lead-out portion of the cover 11 It is possible to extend radially outward along 32.
The inlet pipe 28 and the outlet pipe 29 that protrude outward in the radial direction from the outer peripheral surface of the cover 11 are connected to a control device (not shown). The temperature adjusting medium supplied to the inlet pipe 28 from this control device (not shown) flows into the temperature adjusting medium passage 20 having a spiral groove shape from the inlet 23 to adjust the temperature of the bearing 6, and then from the outlet 24. It returns to the control device (not shown) through the outlet pipe 29.
[0022]
A temperature detecting means for detecting the temperature of the bearing temperature adjusting medium is provided so as to detect the outlet temperature of the temperature adjusting medium in the bearing 6. The temperature detection means is configured to control the temperature of the bearing temperature adjusting medium by a control device. Although not shown, the rotor temperature adjusting device 18 is also provided with temperature detecting means.
The gear pump is of a self-lubricating type in which a part of the transport molten resin is supplied as a lubricant for the bearing 6 and the shaft portion 8. As this self-lubricating structure, a publicly known one (for example, one described in a gazette listed in the prior art) can be adopted, and the detailed description thereof is omitted. The visco seal 16 prevents external leakage of molten resin used for bearing lubrication.
[0023]
As shown in FIG. 4, the molten resin is supplied to the first clearance 34 between the outer peripheral surface of the shaft portion 8 of the rotor 2 and the inner peripheral surface of the bearing 6 to be used for bearing lubrication, and the outer periphery of the bearing 6. It also enters the second clearance 35 between the surface and the inner peripheral surface of the rotor housing hole 3 of the body 1.
The molten resin of the first clearance 34 is prevented from external leakage from the shaft portion 8 by the Bisco seal 16, and is also in contact with the outer end surface of the intermediate plate 10 and the bearing 6 and also in the middle. Due to the surface contact between the plate 10 and the inner end surface of the cover 11, leakage to the insertion hole 31 of the intermediate plate 10 and the lead-out portion 32 of the cover 11 is prevented.
[0024]
In addition, the resin of the part shown with the code | symbol 33 is sealed by the outer end surface of the intermediate | middle plate 10, and the inner end surface of the cover 11, and it has the structure which returns this part resin to the suction side.
Further, the molten resin of the second clearance 35 is brought into contact with the inner end surface of the intermediate plate 10 and the outer end surface of the bearing 6 (in this embodiment, the end surface of the thrust plate 12). Leakage to the insertion hole 31 is prevented.
That is, both end surfaces of the intermediate plate 10 are configured as sealing surfaces for preventing molten resin leakage.
[0025]
Next, the operation of the molten resin conveying gear pump having the above-described configuration will be described.
When the gear pump is started, a heating medium is supplied from a control device (not shown) to the rotor temperature adjusting device 18 and the bearing temperature adjusting device 19 to preheat the rotor 2 and the bearing 6 and prevent the molten molten resin from being cooled and solidified. . When preheating is finished and the molten resin starts to be conveyed, the temperature of the heating medium is lowered to switch to the cooling medium, the rotor 2 and the bearing 6 are cooled, the heat generation of the lubricating resin for lubrication is suppressed, and the Reduces the bearing support ability by suppressing the viscosity drop.
[0026]
Note that it is also possible to provide a cooling medium supply source and a heating medium supply source separately and switch the medium using a supply medium switching valve. In this case, oil, water, air or the like can be used as the cooling medium among the temperature control medium, and oil can be mainly used as the heating medium.
Further, the control devices of the rotor temperature adjusting device and the bearing temperature adjusting device can be used as a single device. Further, the rotor temperature and the bearing temperature can be individually controlled.
[0027]
The leakage of the temperature control medium is prevented with high reliability because the bearing 6 is connected to the inlet pipe 28 and the outlet pipe 29 through the watertight means 30.
Further, the leakage of the molten resin is reliably prevented by providing the intermediate plate 10 and using both end surfaces as sealing surfaces. In this case, if the intermediate plate 10 is not provided, it is difficult to prevent leakage from the second clearance 35 to the U-shaped lead-out portion 32 of the cover 11.
In addition, the provision of the intermediate plate 10 has an effect of facilitating assembly in addition to enhancing the sealing effect of the molten resin. That is, since the cover 11 is heavy, it was very difficult to assemble the cover 10 on the end face of the body 1 while inserting the inlet pipe 28 and the outlet pipe 29 protruding from the end face of the bearing 6. By providing, it becomes possible to set it as the structure (U-shaped derivation | leading-out part 32) which does not need to insert the inlet pipe 28 and the outlet pipe 29, and can attain assembly.
[0028]
FIG. 6 shows another embodiment of the present invention, which is different from the above embodiment in that a seal member is provided instead of using both end faces of the intermediate plate 10 as seal faces. is there.
That is, an O-ring fitting groove is formed in the periphery of the inlet pipe insertion hole 31 and the outlet pipe insertion hole 31 on the bearing side end face of the intermediate plate 10, and the first O ring 36 as a seal member is fitted into the groove. Are combined. Further, an O-ring fitting groove concentric with the rotor shaft center is formed in the end surface on the cover side of the intermediate plate 10 on the inner peripheral side of the rotor shaft center from the insertion hole 31, and a seal member is provided in the groove. A certain second O-ring 37 is fitted.
[0029]
Note that one surface of the intermediate plate 10 may be interposed via the sealing member 36 or 37, and the other surface may be the sealing surface itself. Further, a concave groove is provided on the intermediate plate side of the thrust plate 12 and the first O-ring 36 is fitted therein, or a concave groove is provided on the intermediate plate side of the cover 11 and the second O-ring is provided there. 37 may be fitted.
FIG. 7 shows another embodiment of the present invention, in which a part of the inlet pipe 28 and outlet pipe 29 is not a flexible tube, but is a rigid pipe bent at a right angle using an elbow 38. It is. Other configurations are the same as those described above.
[0030]
FIG. 8 shows another embodiment of the present invention, in which the thrust plate 12 is configured separately from the bearing 6, and the thrust plate 12 is used as the intermediate plate 10 of the present invention. is there.
In this embodiment, the inlet pipe 28 and the outlet pipe 28 are extended in the axial direction, and the outlet pipe 28 and the outlet pipe 29 are inserted into the flange portions of the cover 11 and the Bisco seal 16 in a loose fitting manner. The portion 32 is provided in parallel to the axis of the rotor 2. The lead-out portion 32 is formed to be considerably larger than the inlet pipe 28 and the outlet pipe 29, so that the cover 11 can be easily assembled. A bite pipe joint 39 is provided between the end of the lead-out portion 32 of the visco seal 16 and the inlet pipe 28 and outlet pipe 29 to prevent liquid leakage.
[0031]
In the present invention, in order to enhance the sealing effect of the intermediate plate 10, the fastening means 40 (see FIG. 1) pulls the bearing 6 in the direction of the cover 11 and clamps the intermediate plate 10 with a large force to increase the surface pressure. ) Is preferably provided on the visco seal 16. As the fastening means 40, as indicated by a virtual line A in FIG. 1, apart from screwing the Bisco seal mounting bolt 17 into the cover 11, the cover 6 and the intermediate plate 10 penetrate through the bearing 6 (thrust in the illustrated example). The plate 12) should be screwed. By configuring in this way, the L / D (length versus diameter) of the bolt 40 can be made sufficiently large, and the movement of the bearing 6 can be ensured by the bending of the bolt 40.
[0032]
The bolt 17 may be threaded into the intermediate plate 10 through the cover 11 to increase the surface pressure on the outer end surface side of the intermediate plate 10. If comprised in this way, the movement of the bearing 6 can be made free compared with what is screwed together with the bearing 6. FIG.
The inner peripheral surface of the bearing 6 is preferably subjected to Ag plating. By plating in this way, in combination with the cooling structure of the bearing 6, even if the peripheral speed of the rotor shaft portion 8 is 0.5 m / s or more, a long life of 10 to 20 years can be achieved.
[0033]
The direction of the piping of the inlet pipe 28 and the outlet pipe 29 is preferably set obliquely downward with respect to the horizontal direction. In this way, by piping downward, even if a resin leak occurs, it does not return to the gear pump through the piping and is discharged to the outside.
The present invention is not limited to the one shown in the above embodiment. For example, in the broadest concept of the invention, the invention is not limited to the one for transporting a molten resin. The derivation direction is not particularly limited. Further, the temperature adjustment medium may be only the cooling medium.
[0034]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, while maintaining a bearing free state, the gear pump for high-viscosity liquid conveyance which aimed at the reliability improvement with respect to cooling-medium leak or molten resin leak can be provided.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a gear pump showing an embodiment of the present invention, and is a cross-sectional view taken along line AA in FIG.
FIG. 2 is a left side view of FIG. 1;
FIG. 3 is a circumferential development view of a temperature control medium passage.
FIG. 4 is an enlarged sectional view of a main part of the embodiment of the present invention.
FIG. 5 is a view taken in the direction of arrow A in FIG. 4;
FIG. 6 is an enlarged cross-sectional view of a main part showing another embodiment of the present invention.
FIG. 7 is an enlarged cross-sectional view of the main part showing another embodiment of the present invention.
FIG. 8 is an enlarged cross-sectional view of a main part showing another embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Body 2 Rotor 6 Bearing 10 Intermediate | middle plate 11 Cover 12 Thrust plate 16 Visco seal 20 Temperature control medium path 28 Inlet pipe 29 Outlet pipe 30 Watertight means 31 Insertion hole 32 Lead-out part 36 Seal member (1st O-ring)
37 Seal member (second O-ring)
40 Fastening means

Claims (8)

In a gear pump in which a pair of gear rotors are supported on a body of a gear pump via a bearing, a cover for preventing the bearing from being pulled out in an axial direction is fixed to the body, and a temperature control medium passage is formed in the bearing.
An inlet pipe and an outlet pipe to the temperature control medium passage are connected to the axially outer end surface of the bearing,
An intermediate plate is interposed between the axially outer end surface of the bearing and the cover, and the intermediate plate is provided with insertion holes for the inlet pipe and the outlet pipe,
The gear pump according to claim 1, wherein the cover is provided with a lead-out portion that loosely fits the inlet pipe and the outlet pipe and guides them to the outside. 2. The gear pump according to claim 1, wherein the gear pump is used for conveying a molten resin, and the bearing is held in a non-fixed state with respect to the body and is lubricated by the molten resin. 3. The gear pump according to claim 1, wherein the lead-out portion is recessed in the radial direction of the rotor on the end surface on the intermediate plate side of the cover. The gear pump according to any one of claims 1 to 3, wherein both end faces of the intermediate plate are seal faces. The gear pump according to any one of claims 1 to 3, wherein both end faces of the intermediate plate are in contact with the bearing and the cover via a seal member. The gear pump according to any one of claims 1 to 5, wherein the inlet pipe and the outlet pipe are attached to the bearing via watertight means. The gear pump according to any one of claims 1 to 6, wherein the intermediate plate is constituted by a thrust plate provided for axial positioning of the bearing. A visco seal for preventing liquid leakage from the gear rotor is provided at an axially outward position of the bearing, and the visco seal is provided with a fastening means for increasing the mounting surface pressure between the intermediate plate and the cover. The gear pump according to claim 1, wherein the gear pump is provided.

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