Gear pump for molten resin

Abstract

To improve the durability of the gear rotor shaft through which the temperature-regulating fluid flows. [Solution] The gear pump 10 for molten resin includes a first gear rotor shaft 11 having a first gear portion 16 and a first shaft portion 15, with a first hole 23 formed therein extending along the axial direction of the first shaft portion 15; a second gear rotor shaft 12 having a second gear portion 18 that meshes with the first gear portion 16; a first coupler 27 fixed to one end of the first shaft portion 15; and a first pipe 34 connected to the first coupler 27 inside the first hole 23 and constituting a fluid passage for temperature control fluid introduced via the first coupler 27. The first gear rotor shaft 11 has a first support 36 into which the first pipe 34 is fitted at a position spaced apart from the first coupler 27. The first pipe 34 is fixed to the first gear rotor shaft 11 by the first coupler 27 and the first support 36.

Description

Technical Field

[0001] The present invention relates to a gear pump for molten resin. Background Art

[0002] Conventionally, as disclosed in Patent Document 1, a gear pump for molten resin for discharging molten resin is known. As shown in Fig. 15, the gear pump for molten resin disclosed in Patent Document 1 comprises a body having a rotor accommodation hole formed therein, and a pair of gear rotor shafts disposed within the rotor accommodation hole. When the gear rotor shafts rotate in a state where gear portions provided on the pair of gear rotor shafts are meshed with each other, molten resin is extruded from the rotor accommodation hole. Each gear rotor shaft is provided with an axially extending hole, and a pipe is inserted into the hole. An outer end portion of the pipe is connected to a rotary joint, and an annular gap is formed between the pipe and an inner circumferential surface of the hole. This annular gap functions as a coolant passage through which a coolant flowing inside the pipe and flowing out from a tip end of the pipe returns to the rotary joint side. Prior Art Documents Patent Documents

[0003] Patent Document 1 Japanese Patent Laid-Open No. 2002-139062 Summary of the Invention Problem to be Solved by the Invention

[0004] In the aforementioned gear pump for molten resin, the base end of the pipe 107 is connected to a rotary joint 108 through which a temperature-regulating fluid flows within the gear rotor shaft 103, while the tip of the pipe 107 is not restrained. Therefore, the pipe 107 is cantilevered. Consequently, when the gear rotor shaft 103 rotates, the centrifugal force from the temperature-regulating fluid acting on the pipe 107 causes it to wobble, displacing its tip. This wobbling causes the pipe 107 to repeatedly contact and separate from the inner surface of the hole 106 (fluid passage) within the gear rotor shaft 103. This may damage the surface of the hole 106 or the surface of the pipe 107 (i.e., the surface of the fluid passage). Furthermore, if the rotation of the gear rotor shaft 103 continues, the bending load acting on the pipe 107 by the temperature-regulating fluid may cause cracks to form at the base end of the pipe 107.

[0005] Therefore, the present invention has been made in view of the above-mentioned prior art, and its objective is to improve the durability of the gear rotor shaft through which the temperature control fluid flows in a gear pump for molten resin. [Means for solving the problem]

[0006] To achieve the above objective, the present invention provides a gear pump for dispensing molten resin, comprising: a first gear rotor shaft having a first gear portion and a first shaft portion, with a first hole formed therein extending along the axial direction of the first shaft portion; a second gear rotor shaft having a second gear portion and a second shaft portion that mesh with the first gear portion, with a second hole formed therein extending along the axial direction of the second shaft portion; a first coupler fixed to one end of the first shaft portion; a second coupler fixed to one end of the second shaft portion; a first pipe connected to the first coupler inside the first hole and constituting a fluid passage for a temperature control fluid introduced via the first coupler; and a second pipe connected to the second coupler inside the second hole and constituting a fluid passage for a temperature control fluid introduced via the second coupler. The first gear rotor shaft has a first support body into which the first pipe is fitted at a position spaced apart from the first coupler in the axial direction of the first shaft portion. The second gear rotor shaft has a second support body into which the second pipe is fitted at a position spaced apart from the second coupler in the axial direction of the second shaft portion. The first pipe is fixed to the first gear rotor shaft by the first coupler and the first support body. The second pipe is fixed to the second gear rotor shaft by the second coupler and the second support body.

[0007] In the aforementioned gear pump for molten resin, the first pipe is connected to the first coupler, while the first pipe is fitted to a first support structure that is spaced apart from the first coupler in the axial direction. Furthermore, the first pipe is fixed to the first gear rotor shaft by the first coupler and the first support structure. In other words, the first pipe is constrained so as not to be displaced when the first gear rotor shaft rotates. This suppresses the runout and shaft vibration of the first pipe. Similarly, the runout and shaft vibration of the second pipe can also be suppressed. Moreover, during gear pump operation, contact between the first pipe and the inner surface of the first hole of the first gear rotor shaft is prevented, and contact between the second pipe and the inner surface of the second hole of the second gear rotor shaft is prevented. This prevents wear and damage to the surfaces of the first and second holes (surfaces of the fluid passages) on the first and second gear rotor shafts.

[0008] The flow of the temperature-regulating fluid may be blocked at the tip of the first pipe. In this case, a communication port may be formed on the side of the first pipe that allows the flow of the temperature-regulating fluid between the inside and outside of the first pipe.

[0009] In this embodiment, the temperature-regulating fluid does not flow inside or outside the first pipe at its tip, but it can flow between the inside and outside of the first pipe through a communication port. In this case, the first pipe may be made of a pipe material with a closed tip, or even if the tip of the first pipe is open, the opening at the tip may face a closed space, resulting in a configuration where the temperature-regulating fluid does not flow through the opening at the tip.

[0010] The first hole in the first gear rotor shaft may be a through hole that penetrates the first gear rotor shaft. In this case, the first support may be composed of a plug that closes the through hole and into which the tip of the first pipe is fitted.

[0011] In this embodiment, since the first hole in the first gear rotor shaft is formed as a through hole, even if the first hole is formed by drilling, chips or shavings are easily discharged from the first hole. Therefore, it is possible to prevent damage to the inner circumferential surface (the surface of the fluid passage) of the first hole. In addition, although the tip of the first pipe is closed by a plug, the flow of the temperature control fluid can be ensured by the communication port.

[0012] The first support has an insertion hole into which the tip of the first pipe is inserted, and the fitting of the first pipe to the insertion hole may be an intermediate fit.

[0013] In this embodiment, the gap between the outer surface of the first pipe and the inner surface of the insertion hole in the first support is small. Therefore, compared to the case where the fitting to the first support is a clearance fit, the impact of the first pipe contacting the first support due to the vibration of the first pipe is suppressed, and noise can be suppressed. Also, compared to the case where the fitting to the first support is a tight fit, the first pipe is easier to remove from the first support, resulting in improved maintainability. In other words, the first gear rotor shaft is easier to disassemble.

[0014] The first support may have a projection that is inserted into the first pipe. In this case, the fitting of the projection to the first pipe may be an intermediate fit.

[0015] In this embodiment, the gap between the inner surface of the first pipe and the outer surface of the projection is small. Therefore, compared to the case where the projection is fitted to the first pipe by clearance, the impact of the first pipe contacting the projection due to the first pipe's rotation is suppressed, and noise can be reduced. Also, compared to the case where the projection is fitted to the first pipe by interference, the first pipe is easier to remove from the projection, resulting in improved maintainability. In other words, the first gear rotor shaft is easier to disassemble.

[0016] The projection may be tapered, and the outer diameter of the tip of the projection may be smaller than the inner diameter of the first pipe.

[0017] In this embodiment, after inserting the first pipe into the first hole of the first gear rotor shaft, it is easier to insert the tip of the projection into the first pipe. Therefore, the ease of assembling the first support to the first pipe can be improved. [Effects of the Invention]

[0018] As described above, according to the present invention, the durability of the gear rotor shaft through which the temperature control fluid flows in a gear pump for molten resin can be improved. [Brief explanation of the drawing]

[0019] [Figure 1]It is a cross-sectional view schematically showing the gear pump for molten resin according to the first embodiment. [Figure 2] It is a schematic cross-sectional view of a gear portion of the gear pump. [Figure 3] It is a diagram for explaining the configuration near the coupler-side end of the gear rotor shaft of the gear pump. [Figure 4] It is a diagram for explaining the configuration near the portion into which the tip end of the gear rotor shaft is fitted. [Figure 5] It is a diagram for explaining a modified example of the portion into which the tip end of the gear rotor shaft is fitted. [Figure 6] It is a diagram for explaining a modified example of the communication port of the gear rotor shaft. [Figure 7] It is a diagram for explaining the configuration near the portion into which the tip end of the gear rotor shaft is fitted, in the gear pump for molten resin according to the second embodiment. [Figure 8] It is a schematic cross-sectional view of the fitted portion. [Figure 9] It is a diagram for explaining the configuration of a modified example of the fitted portion. [Figure 10] It is a schematic cross-sectional view of the fitted portion. [Figure 11] It is a diagram for explaining the configuration near the portion into which the tip end of the gear rotor shaft is fitted, in the gear pump for molten resin according to the third embodiment. [Figure 12] It is a diagram for explaining the configuration of a modified example of the fitted portion. [Figure 13] It is a diagram for explaining the configuration of a modified example of the fitted portion. [Figure 14] It is a diagram for explaining the configuration of a modified example of the fitted portion. [Figure 15] It is a cross-sectional view showing a conventional gear pump. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, modes for carrying out the present invention will be described in detail with reference to the drawings.

[0021] (First Embodiment) The gear pump 10 for molten resin according to this embodiment (hereinafter simply referred to as the gear pump 10) is used to pump molten resin, which has been kneaded by a kneader (not shown), downstream. As shown in Figure 1, the gear pump 10 comprises a pair of gear rotor shafts (a first gear rotor shaft 11 and a second gear rotor shaft 12), a drive unit 13 that generates a driving force to rotate the first gear rotor shaft 11 and the second gear rotor shaft 12 around their axes, and a body 14 through which the first gear rotor shaft 11 and the second gear rotor shaft 12 are inserted.

[0022] The first gear rotor shaft 11 has a first shaft portion 15 extending in one direction and a first gear portion 16 provided in the middle of the longitudinal direction of the first shaft portion 15. The second gear rotor shaft 12 has a second shaft portion 17 extending in a direction parallel to the first shaft portion 15 and a second gear portion 18 provided in the middle of the longitudinal direction of the second shaft portion 17 and meshing with the first gear portion 16. The drive unit 13 is connected to one end of the first shaft portion 15 (first end 15a) and one end of the second shaft portion 17 (first end 17a), and rotates the first shaft portion 15 and the second shaft portion 17 synchronously.

[0023] The body 14 has an insertion space 14a that penetrates between its opposite sides, and the first gear rotor shaft 11 and the second gear rotor shaft 12 are inserted into this insertion space 14a. The first shaft portion 15 is rotatably supported by the body 14 via first bearings 19 on both sides of the first gear portion 16, and the second shaft portion 17 is rotatably supported by the body 14 via second bearings 20 on both sides of the second gear portion 18.

[0024] When the gear pump 10 for molten resin is stopped for maintenance or other reasons and then restarted, the resin that has entered the gap between the first gear rotor shaft 11 and the first bearing 19, and the gap between the second gear rotor shaft 12 and the second bearing 20, will have cooled and solidified. Therefore, before restarting the gear pump 10, a temperature control fluid is circulated through the first gear rotor shaft 11 and the second gear rotor shaft 12 to heat them and melt the solidified resin. Furthermore, after restarting the gear pump 10 for molten resin, if the operation of pumping molten resin continues with the first gear rotor shaft 11 and the second gear rotor shaft 12 rotating at high speed, the temperature of the first gear rotor shaft 11 and the second gear rotor shaft 12 will rise. Therefore, the first gear rotor shaft 11 and the second gear rotor shaft 12 are cooled by the temperature control fluid. The temperature-regulating fluid may be, for example, water or oil, but is not limited to these.

[0025] The first shaft portion 15 and the first end 15a of the second shaft portion 17 are connected to the drive unit 13 on the outside of the body 14. The other end (second end 15b) of the first shaft portion 15 and the other end (second end 17b) of the second shaft portion 17 extend outward from the side of the body 14 opposite to the drive unit 13, and the first coupler 27 or the second coupler 42, which will be described later, are connected to these second ends 15b and 17b.

[0026] In the extending direction of the first shaft portion 15, the portion of the insertion space 14a where the first gear portion 16 and the second gear portion 18 are located becomes a resin space 14b (see Figure 2) through which molten resin passes. As shown in Figure 2, this resin space 14b includes a receiving passage 14c for receiving molten resin from outside the body 14 and a discharge passage 14d for discharging the molten resin. The receiving passage 14c opens on one side of the body 14, and the discharge passage 14d opens on the other side of the body 14. A pressure difference is created at both ends of the first bearing 19 in the axial direction of the first shaft portion 15 due to the pressure of the resin inside the body 14 and the atmospheric pressure outside the body 14. A similar pressure difference is also created for the second bearing 20. A portion of the molten resin introduced into the body 14 through the receiving passage 14c is drawn into the gap between the first bearing 19 and the first shaft portion 15 and the gap between the second bearing 20 and the second shaft portion 17 due to the pressure difference. This ensures lubrication of the first bearing 19 and the second bearing 20.

[0027] The following describes the first gear rotor shaft 11, the second gear rotor shaft 12, and their associated components. However, since the first gear rotor shaft 11 and the second gear rotor shaft 12 have the same configuration, only the configuration of the first gear rotor shaft 11 will be described, and the description of the second gear rotor shaft 12 will be omitted. Note that the second gear rotor shaft 12 and its associated components can be understood by replacing "first" with "second".

[0028] The first gear rotor shaft 11 has a first hole 23 formed therein, which is a hole extending along the axial direction of the first shaft portion 15. The first hole 23 opens to the end face of one end (first end 15a) of the first shaft portion 15 and also opens to the end face of the other end (second end 15b) of the first shaft portion 15. In other words, the first hole 23 is machined as a hole that penetrates the center of the first shaft portion 15, and the first hole 23 is a through hole that penetrates the first gear rotor shaft 11 in the axial direction.

[0029] The first hole 23 may be formed, for example, by drilling (rough machining and finishing machining). If the first hole 23 is a through hole, chips can be discharged from the opening at the end during finishing machining, making it less likely for scratches to occur on the surface of the first hole 23. In addition, during surface inspection after drilling, scratches on the surface are easier to detect because the inside of the first hole 23 is bright. This prevents defective first gear rotor shafts 11 from being shipped. Therefore, defects that could lead to damage to the first gear rotor shaft 11, namely the occurrence of cracks starting from scratches, can be prevented.

[0030] The opening on the first end 15a side of the first hole 23 is closed by a plug (first plug 25) positioned to enter the first hole 23. The first plug 25 has a columnar portion 25a having an outer diameter approximately the same as the inner diameter of the first hole 23, and a flange portion 25b provided at the outer end of the columnar portion 25a.

[0031] The first plug 25 is fixed to the first shaft portion 15 by fasteners at the flange portion 25b, and is therefore detachable from the first shaft portion 15. However, the first plug 25 does not necessarily have to be configured to be detachable.

[0032] A first coupler 27 is positioned in the opening on the second end 15b side of the first hole 23. The first coupler 27 is fixed to the second end 15b of the first shaft portion 15 and closes the opening on the second end 15b side of the first hole 23. As shown in Figure 3, the first coupler 27 integrally comprises a main body portion 27a attached to the end face of the first shaft portion 15 by fasteners, and a support portion 27b that protrudes from the center of one face of the main body portion 27a.

[0033] A first rotary joint 28 is connected to the first coupler 27 for supplying temperature-controlling fluid. The first rotary joint 28 is configured to supply temperature-controlling fluid from a source to the rotating first pipe 34. The first rotary joint 28 is also configured to allow the temperature-controlling fluid that has flowed out of the first pipe 34 to be discharged to the outside of the first rotary joint 28.

[0034] Specifically, the first rotary joint 28 has a rotating part 29 that can rotate integrally with the first gear rotor shaft 11 and the first coupler 27, and a fixed part 30 that rotatably holds the rotating part 29 via a bearing 31. The rotating part 29 has a double-tube structure and includes an outer tube 29a and an inner tube 29b. The outer tube 29a has a tube portion 29d and a flange portion 29c, and this flange portion 29c is fixed to the first coupler 27. The inner tube 29b is located inside the outer tube 29a, and a temperature-regulating fluid flows through the space between the inner tube 29b and the outer tube 29a. A temperature-regulating fluid also flows inside the inner tube 29b. The inner tube 29b is located along the axis of the rotating part 29 and rotates around the axis so as not to oscillate during rotation.

[0035] The support portion 27b of the first coupler 27 has a central hole 27c into which the inner tube 29b of the first rotary joint 28 is inserted. The first pipe 34, which will be described later, is also inserted into this central hole 27c, and the inner space of the inner tube 29b and the inner space of the first pipe 34 are in communication with each other.

[0036] In this embodiment, the temperature-controlling fluid flows from the inner space of the inner pipe 29b toward the inner space of the first pipe 34. The temperature-controlling fluid that has flowed through the first pipe 34 flows out into the first hole 23 through the communication port 38, which will be described later, and this outflowed temperature-controlling fluid returns to the first coupler 27. The first coupler 27 has a plurality of peripheral holes 27d that connect the space inside the first hole 23 with the space between the inner pipe 29b and the outer pipe 29a in the first rotary joint 28. The plurality of peripheral holes 27d are formed around the central hole 27c at intervals from each other. The temperature-controlling fluid flows from the first hole 23 toward the space between the inner pipe 29b and the outer pipe 29a through each peripheral hole 27d. The direction of the flow of the temperature-controlling fluid may be reversed.

[0037] A first pipe 34 is positioned in the first hole 23 of the first gear rotor shaft 11. The first pipe 34 is made of a tubular material with an open base and a closed tip. The base of the first pipe 34 is inserted into the central hole 27c of the first coupler 27. Therefore, the inner space of the first pipe 34 communicates with the inner space of the inner pipe 29b within the central hole 27c. Furthermore, because the first pipe 34 is inserted into the central hole 27c of the first coupler 27, the first pipe 34 is supported at its base by the support portion 27b of the first coupler 27. The first pipe 34 constitutes a fluid passage for the temperature control fluid on both the inside and outside of the tubular material.

[0038] On the other hand, as shown in Figure 4, the tip of the first pipe 34 is supported by the first plug 25. The first plug 25 is provided with a fitting portion 35 into which the first pipe 34 fits. The fitting portion 35 is provided at the inner end (tip) of the columnar portion 25a.

[0039] The mating portion 35 has a recessed insertion hole 35a, and the tip of the first pipe 34 is inserted into this insertion hole 35a. As a result, the tip of the first pipe 34 is supported by the first plug 25. In other words, the first plug 25 constitutes a first support 36 into which the first pipe 34 is mated at a position spaced apart from the first coupler 27 in the axial direction of the first shaft portion 15. The first pipe 34 is then fixed to the first gear rotor shaft 11 by the first coupler 27 and the first support 36.

[0040] The fitting of the tip of the first pipe 34 to the insertion hole 35a is an intermediate fit. In terms of fit tolerance standards (JIS-B 0401-1,2), it is preferable to design the tolerance zone class of the hole and the tolerance zone class of the shaft to be, for example, reference hole H6 with reference shaft h5, reference hole H7 with reference shaft h6, reference hole H8 with reference shaft h7 or h8, and reference hole H9 with reference shaft h9.

[0041] The first plug 25 is fixed to the first gear rotor shaft 11 at the flange portion 25b, and the outer diameter of the columnar portion 25a is approximately the same as the inner diameter of the first hole 23. Therefore, during rotation of the first gear rotor shaft 11, the inner end of the first plug 25, i.e., the fitting portion 35, is not displaced radially.

[0042] Furthermore, the tip of the first pipe 34 is inserted into the fitting portion 35 of the first plug 25, thereby preventing the flow of the temperature-regulating fluid at the tip of the first pipe 34.

[0043] On the other hand, a communication port 38 is formed on the side of the first pipe 34. The communication port 38 is located on the side of the first pipe 34 at a position closer to the tip than the center in the longitudinal direction of the first pipe 34. Since the communication port 38 is located outside the insertion hole 35a of the first plug 25, when the first pipe 34 is inserted into the insertion hole 35a, the communication port 38 allows the flow of temperature-regulating fluid between the inside and outside of the first pipe 34.

[0044] As described above, the second gear rotor shaft 12 has the same configuration as the first gear rotor shaft 11. Therefore, as shown in Figure 1, the second gear rotor shaft 12 has a second hole 39 extending in the axial direction of the second shaft portion 17, and the second pipe 40 is placed in the second hole 39. The opening on the first end 17a side of the second hole 39 is closed by the second plug 41. A second coupler 42 is fixed to the second end 17b of the second shaft portion 17, and a second rotary joint 43 is connected to the second coupler 42.

[0045] The operation of the gear pump 10 will now be described. When the first gear rotor shaft 11 and the second gear rotor shaft 12 rotate around their axes by the drive unit 13, the first gear section 16 and the second gear section 18 rotate while meshing with each other. As a result, molten resin from the kneader is drawn into the resin space 14b through the receiving passage 14c of the body 14. This molten resin is formed between the tooth grooves of each gear section 16, 18 and the inner circumferential surface of the body 14, and is conveyed by the space that moves circumferentially with the rotation of the gear rotor shafts 11, 12, and is finally sent to the downstream side of the gear pump 10 through the discharge passage 14d of the body 14.

[0046] During the operation of the gear pump 10, a temperature-regulating fluid flows through the first gear rotor shaft 11 and the second gear rotor shaft 12. Specifically, in the first gear rotor shaft 11, the temperature-regulating fluid supplied from the source flows into the first pipe 34 through the internal space of the inner pipe 29b of the first rotary joint 28. At this time, the central hole 27c may function as an inflow passage for the temperature-regulating fluid to flow toward the first hole 23. The temperature-regulating fluid that has flowed inside the first pipe 34 then flows out to the outside of the first pipe 34 through the communication port 38. This temperature-regulating fluid flows along the outer surface of the first pipe 34 inside the first hole 23 and flows into the space between the outer pipe 29a and the inner pipe 29b of the first rotary joint 28 via the peripheral hole 27d of the first coupler 27. In other words, the peripheral hole 27d of the first coupler 27 functions as an outflow passage for the temperature-regulating fluid flowing out from the first hole 23. In this manner, the first gear rotor shaft 11 is cooled by the circulation of a temperature-regulating fluid within it, and the molten resin is dispensed under these conditions. Similarly, the temperature-regulating fluid also circulates within the second gear rotor shaft 12.

[0047] Furthermore, the flow of the temperature-controlling fluid may be in the opposite direction to the flow described above. That is, the temperature-controlling fluid from the supply source may flow through the space outside the inner pipe 29b of the first rotary joint 28 (or second rotary joint 4340), through the first coupler 27 (or second coupler 4239), and into the first hole 23 (or second hole 39). In this case, the temperature-controlling fluid flows into the first pipe 34 (or second pipe 40) through the communication port 38, and then flows into the inner pipe 29b of the first rotary joint 28 (or second rotary joint 43). That is, the peripheral hole 27d functions as an inflow passage. In this case, the central hole 27c may function as an outflow passage.

[0048] As described above, in the gear pump 10 according to this embodiment, the first pipe 34 is connected to the first coupler 27, while the first pipe 34 is fitted to the first support 36, which is spaced apart from the first coupler 27 in the axial direction. The first pipe 34 is fixed to the first gear rotor shaft 11 by the first coupler 27 and the first support 36. The second pipe 40 is fixed in the same manner. Therefore, when the first gear rotor shaft 11 and the second gear rotor shaft 12 rotate, the first pipe 34 rotates integrally with the first gear rotor shaft 11, generating centrifugal force on the first pipe 34. However, even in this case, the first pipe 34 does not swing around. That is, the first pipe 34 is constrained by the first coupler 27 and the first plug 25 to prevent displacement in both the rotational joint side and the anti-rotational joint side. This makes it possible to suppress swinging and axial vibration of the first pipe 34. The same applies to the second pipe 40. Furthermore, during operation of the gear pump 10, contact between the first pipe 34 and the inner circumferential surface of the first hole 23 of the first gear rotor shaft 11 is prevented. This prevents wear and damage to the surface of the first hole 23 (the surface of the fluid passage) on the first gear rotor shaft 11. The same applies to the second hole 39 of the second gear rotor shaft 12.

[0049] Furthermore, in this embodiment, since the tip of the first pipe 34 is closed, the temperature-controlling fluid does not flow between the inside and outside of the first pipe 34 at this tip. However, a communication port 38 is formed on the side surface of the first pipe 34, and the temperature-controlling fluid can be circulated between the inside and outside of the first pipe 34 through this communication port 38. Therefore, while employing a configuration in which the tip of the first pipe 34 is fixed with the first support 36, the flow of the temperature-controlling fluid can be ensured. The same applies to the second pipe 40.

[0050] Furthermore, in this embodiment, since the first hole 23 of the first gear rotor shaft 11 is formed as a through hole, even if the first hole 23 is formed by drilling, chips or shavings are easily discharged from the first hole 23. Therefore, it is possible to prevent damage to the inner circumferential surface (the surface of the fluid passage) of the first hole 23. In addition, although the tip of the first pipe 34 is closed by the first plug 25, the communication port 38 ensures the flow of the temperature control fluid. The same applies to the second pipe 40.

[0051] Furthermore, in this embodiment, since the fitting of the first pipe 34 to the insertion hole 35a provided in the first plug 25 is an intermediate fit, the gap between the outer surface of the first pipe 34 and the inner surface of the insertion hole 35a of the first support 36 is small. Therefore, compared to the case where the fitting to the first support 36 is a clearance fit, the impact when the first pipe 34 contacts the first support 36 due to the vibration of the first pipe 34 is suppressed, and noise can be suppressed. The same applies to the second pipe 40. Also, compared to the case where the fitting to the first support 36 is a tight fit, the first pipe 34 is easier to remove from the first support 36, resulting in better maintainability. In other words, the first gear rotor shaft 11 is easier to disassemble. The same applies to the second gear rotor shaft 12.

[0052] In this embodiment, the first support 36 is composed of a fitting portion 35 having an insertion hole 35a, but it is not limited to this. For example, as shown in Figure 5, the fitting portion 35 may have a projection 35b that is inserted into the tip opening of the first pipe 34. The projection 35b is provided at the inner end (tip) of the columnar portion 25a of the first plug 25. Similarly, the second support may also have a projection into which the second pipe 40 is introduced.

[0053] In this case, it is preferable that the fitting of the projection 35b to the first pipe 34 is an intermediate fit. The same applies to the second pipe 40. In other words, in terms of the fit tolerance standards (JIS-B 0401-1,2), it is preferable that the tolerance zone class of the hole and the tolerance zone class of the shaft are, for example, a reference shaft h5 for a reference hole H6, a reference shaft h6 for a reference hole H7, a reference shaft h7 or h8 for a reference hole H8, and a reference shaft h9 for a reference hole H9 (smooth fit).

[0054] Furthermore, in this embodiment and the modified example in Figure 5, the shape of the communication port 38 is round, but the shape is not limited to round. For example, the shape of the communication port 38 may be elliptical, rectangular, or the like. Also, as shown in Figure 6, the communication port 38 may have an elongated shape that extends to the tip of the first pipe 34. In other words, any shape that allows the temperature control fluid to flow while maintaining the strength of the first pipe 34 is acceptable. The same applies to the second pipe 40.

[0055] (Second Embodiment) As shown in Figure 7, in the second embodiment, the first support 36 into which the first pipe 34 is fitted is composed of a spacer 46 positioned at the axial intermediate position of the first hole 23. The same applies to the second pipe 40. Here, the same reference numerals are used for components that are the same as in the first embodiment, and their detailed descriptions are omitted.

[0056] Specifically, the first gear rotor shaft 11 has a cylindrical extension 47 that partitions the first hole 23, which is a through hole, a closing portion 48 that closes the opening on the first end 15a side of the first hole 23, and a spacer 46. Therefore, since the first hole 23 is closed by the closing portion 48, the temperature control fluid in the first hole 23 does not leak out from the first end 15a side. The closing portion 48 is made of a separate component from the component that makes up the spacer 46.

[0057] The spacer 46 is positioned within the first hole 23 at a location spaced apart from the closing portion 48. Specifically, the spacer 46 is positioned towards the tip of the first pipe 34, rather than towards the center in the longitudinal direction. Because the spacer 46 is spaced apart from the closing portion 48, the space within the first hole 23 is divided into multiple spaces by the spacer 46.

[0058] The spacer 46 is press-fitted into the first hole 23. Therefore, the spacer 46 does not vibrate during the rotation of the first gear rotor shaft 11. Also, as shown in Figure 8, the spacer 46 is ring-shaped, and the first pipe 34 is inserted into the inner hole of the spacer 46. In this state, the first pipe 34 is fixed to the first gear rotor shaft 11. Note that the fitting of the first pipe 34 to the spacer 46 may be an intermediate fit.

[0059] Since the tip of the first pipe 34 is closed, the temperature-regulating fluid inside the first pipe 34 does not flow out from its tip. In other words, the flow of the temperature-regulating fluid is blocked at the tip of the first pipe 34. On the other hand, since a communication port 38 is formed in the first pipe 34 at a position closer to the first coupler 27 than the spacer 46, the temperature-regulating fluid inside the first pipe 34 flows out into the first hole 23 through the communication port 38, and this temperature-regulating fluid can return to the first coupler 27 side. Furthermore, since the temperature-regulating fluid does not pass through the spacer 46, even if the tip of the first pipe 34 were open, the temperature-regulating fluid would not flow through the tip of the first pipe 34.

[0060] Since the second gear rotor shaft 12 is configured in the same way as the first gear rotor shaft 11, the through hole of the second gear rotor shaft 12 is closed by a closing portion (not shown in the figure). The spacer constituting the second support is also configured in the same way as the spacer 46. Furthermore, the position of the communication port of the second pipe 40 is set to be the same as the position of the communication port 38.

[0061] Furthermore, as shown in Figures 9 and 10, if the tip of the first pipe 34 is open and the temperature control fluid can flow through the spacer 46, the communication port 38 can be omitted. That is, if a through passage (not shown) is formed in the spacer 46 that fits onto the inner circumferential surface of the first gear rotor shaft 11, or if a gap 49 (see Figure 10) is formed between a part of the circumferential surface of the outer circumferential surface of the spacer 46 and the inner circumferential surface of the first gear rotor shaft 11, the temperature control fluid can pass through the spacer 46 through the through passage or gap 49. The second spacer can be configured in the same way.

[0062] In this case, the temperature-regulating fluid that flows out from the tip of the first pipe 34 can return to the first coupler 27 side by passing through the through passage provided in the spacer 46 or through the gap 49 around the spacer 46.

[0063] Note that there may be one or more through passages and gaps 49. The other configurations, functions, and effects will not be described here, but the description of the first embodiment can be applied to the second embodiment.

[0064] (Third embodiment) As shown in Figure 11, in the third embodiment, the first hole 23 (or second hole 39) is formed as a blind hole rather than a through hole. That is, the first hole 23 (or second hole 39) is open at the end face of the second end 15b of the first shaft portion 15, while being closed at the end face of the first end 15a of the first shaft portion 15. Here, the same reference numerals are used for the same components as in the first and second embodiments, and their detailed descriptions are omitted.

[0065] The first gear rotor shaft 11 integrally comprises a cylindrical extension 47 and a closing portion 48 provided at the end of the extension 47 (the end on the first end 15a side) that closes the opening at the end of the extension 47. That is, the extension 47 defines the inner circumferential surface of the first hole 23, and the closing portion 48 defines the end face of the first hole 23 on the first end 15a side.

[0066] The closure portion 48 includes a fitting portion 35 into which the first pipe 34 is fitted. That is, the closure portion 48 constitutes the first support 36. The fitting portion 35 has a recessed insertion hole 35a, and the tip of the first pipe 34 is inserted into this insertion hole 35a. The fitting of the tip of the first pipe 34 into the insertion hole 35a may be an intermediate fit.

[0067] The tip of the first pipe 34 is inserted into the fitting portion 35 of the closure portion 48 (first support 36), thereby preventing the flow of the temperature-regulating fluid at the tip of the first pipe 34. Therefore, the flow of the temperature-regulating fluid is prevented at the tip of the first pipe 34. On the other hand, since a communication port 38 is formed on the side surface of the first pipe 34, the communication port 38 allows the flow of the temperature-regulating fluid between the inside and outside of the first pipe 34.

[0068] The configuration of the second gear rotor shaft 12 is the same as that of the first gear rotor shaft 11. That is, although not shown in the figures, the second gear rotor shaft 12 also integrally has a cylindrical extension and a closing part provided at the end of the extension to close the opening at the end. This closing part constitutes the second support. The closing part (second support) includes a fitting part into which the second pipe 40 is fitted.

[0069] Furthermore, the fitting portion 35 is not limited to having a recessed insertion hole 35a into which the first pipe 34 is inserted. For example, as shown in Figure 12, the fitting portion 35 may have a projection 35b that is inserted into the tip opening of the first pipe 34. The same applies to the fitting portion of the second pipe 40.

[0070] Furthermore, instead of the closing portion 48 constituting the first support 36, the first support 36 may be provided at the end of the first hole 23, as shown in Figures 13 and 14. That is, the first gear rotor shaft 11 may have a cylindrical extension portion 47, a closing portion 48 that closes the opening at the end of the extension portion 47, and a first support 36 positioned adjacent to the closing portion 48. This first support 36 is formed from a separate member from the members constituting the extension portion 47 and the closing portion 48, and is press-fitted into the first hole 23 determined by the extension portion 47 and the closing portion 48. Figure 13 shows a configuration in which the fitting portion 35 of the first support 36 has an insertion hole 35a, and Figure 14 shows a configuration in which the fitting portion 35 of the first support 36 has a projection 35b. The second support can be configured similarly.

[0071] The other configurations, functions, and effects will not be described here, but the descriptions of the first and second embodiments can be applied to the third embodiment.

[0072] (Other embodiments) It should be noted that the embodiments disclosed herein are illustrative and not restrictive in all respects. The present invention is not limited to the embodiments described above, and various modifications and improvements are possible without departing from its spirit. For example, a support having a passage for a temperature-regulating fluid may be further added. This additional support is positioned within the first hole 23 between the first support 36 and the first coupler 27 to support the first pipe 34. There may be one or more additional supports. Furthermore, an additional support may be provided within the second hole 39. [Explanation of Symbols]

[0073] 10: Gear pump for molten resin 11: First gear rotor shaft 12: Second gear rotor shaft 15: First shaft section 16: First gear section 17: Second shaft section 18: Second gear section 23: First hole 25: First plug 27: First coupler 34: First pipe 35a: Insertion hole 35b: Protrusion 36: 1st support 38: Connecting port 39: Second hole 40: Second pipe 41: Second plug 42: Second coupler 46: Spacer

Claims

1. A gear pump for dispensing molten resin, A first gear rotor shaft having a first gear portion and a first shaft portion, with a first hole formed therein extending along the axial direction of the first shaft portion, A second gear rotor shaft having a second gear portion and a second shaft portion that mesh with the first gear portion, and having a second hole formed in the second shaft portion that extends along the axial direction, A first coupler fixed to one end of the first shaft portion, A second coupler fixed to one end of the second shaft portion, A first pipe is connected to the first coupler inside the first hole and constitutes a fluid passage for the temperature control fluid introduced via the first coupler, The second pipe is connected to the second coupler inside the second hole and constitutes a fluid passage for the temperature control fluid introduced via the second coupler, The first gear rotor shaft has a first support into which the first pipe is fitted at a position spaced apart from the first coupler in the axial direction of the first shaft portion. The second gear rotor shaft has a second support body into which the second pipe is fitted at a position spaced apart from the second coupler in the axial direction of the second shaft portion. The first pipe is fixed to the first gear rotor shaft by the first coupler and the first support, The second pipe is fixed to the second gear rotor shaft by the second coupler and the second support. Gear pump for molten resin.

2. The flow of the temperature-regulating fluid is blocked at the tip of the first pipe. The gear pump for molten resin according to claim 1, wherein a communication port is formed on the side surface of the first pipe, allowing the flow of the temperature-regulating fluid between the inside and outside of the first pipe.

3. The first hole in the first gear rotor shaft is a through hole that penetrates the first gear rotor shaft. The gear pump for molten resin according to claim 2, wherein the first support is composed of a plug that closes the through hole and into which the tip of the first pipe is fitted.

4. The gear pump for molten resin according to any one of claims 1 to 3, wherein the first support has an insertion hole into which the tip of the first pipe is inserted, and the fitting of the first pipe to the insertion hole is an intermediate fit.

5. The gear pump for molten resin according to any one of claims 1 to 3, wherein the first support has a projection that is inserted into the first pipe, and the fitting of the projection to the first pipe is an intermediate fit.

6. The gear pump for molten resin according to claim 5, wherein the projection is tapered, and the outer diameter of the tip of the projection is smaller than the inner diameter of the first pipe.

Images