Coupling device and molten resin supply system

Abstract

A molten resin supply system 1 comprises a coupling device 10 that couples a decontamination machine 80 that outputs a molten resin to be recycled from an output port 801 with an injection molding machine 90 having an input port 911 for inputting the output molten resin, a heating cylinder 91 for heating the molten resin, and an injection cylinder that is independent of the heating cylinder 91 and injects the heated molten resin into a mold. One end of piping formed by pipes 11-14 for passing the molten resin and swivel joints 21-23 is connected to the output port 801 through a connection member 31, and the other end is connected to the input port 911 through a connection member 32, thereby coupling the decontamination machine 80 and the injection molding machine 90.

Description

Connection device and molten resin supply system

[0001] The present invention relates to a connection device and a molten resin supply system.

[0002] In some cases, a decontamination machine that uses a mechanical recycling method to decontaminate contaminants contained within a resin to be recycled outputs a molten resin, and the molten resin is then directly input into an injection molding machine. The decontamination machine and the injection molding machine are connected by piping. In this case, a sleeve (a sliding expansion joint) is sometimes provided at the joint of the piping to accommodate the movement of the heating cylinder of the injection molding machine due to the discharge (purging) of the molten resin from the heating cylinder (see, for example, Patent Document 1).

[0003] International Publication No. 2022 / 056618

[0004] When a sleeve is provided as a pipe joint, the sleeve slides in accordance with the movement of the heating cylinder, moving back and forth between the inside and outside of the pipe. In this case, the molten resin passing through the inside of the pipe may be exposed to the outside of the pipe while adhering to the surface of the sleeve. When the sleeve slides, the exposed molten resin may be rubbed and carbonized, or the carbonized resin may mix with the molten resin passing through the inside of the pipe, degrading the molten resin.

[0005] The object of the present invention is to prevent molten resin passing through a pipe from leaking from a joint, compared to when a sleeve is provided as a joint in the pipe connecting the device that outputs the molten resin to the injection molding machine.

[0006] The present invention, which was completed with this object in mind, provides a connecting device that connects an output device that outputs molten resin to be recycled from an output port to an injection molding machine having an input port for inputting the output molten resin, a heating cylinder that heats the molten resin, and an injection cylinder independent of the heating cylinder that injects the heated molten resin into a mold. One end of a pipe formed by a tube through which the molten resin passes and a swivel joint is connected to the output port, and the other end is connected to the input port, thereby connecting the output device and the injection molding machine. The number of swivel joints provided in the connecting device may be three. The swivel joint may have a sealing member with a predetermined heat-resistant temperature and pressure resistance. The connecting device may heat the molten resin passing through the pipe by heating the pipe. The connecting device may heat the pipe using a band heater. The swivel joint may be rotatable using a sliding bearing, and part of the molten resin may be used as a lubricant for the sliding bearing. The rotation axis of the swivel joint may be oriented not parallel to the vertical direction but substantially perpendicular to the direction of movement of the heating cylinder. The imaginary line connecting one end of the piping to the other end may be substantially parallel to the direction of movement of the heating cylinder. The imaginary line connecting the one end of the piping to the other end may be substantially perpendicular to the rotation axis of the swivel joint. The length of a first piping section including a swivel joint closest to the one end of the piping and the length of a third piping section including a swivel joint farthest from the one end may each be 30% or less of the length of a second piping section including a swivel joint disposed between the first piping section and the third piping section. The present invention also provides a molten resin supply system including the output device, the injection molding machine, and the connecting device, wherein the output port of the output device is fixed in position, and the input port of the heating cylinder is movable in position in accordance with movement of the heating cylinder.The present invention also provides a molten resin supply system including the output device, the injection molding machine, and the connecting device, wherein the system performs processing to prevent imaginary lines connecting the rotation axes of the three swivel joints connected via the two pipes from forming a single line when viewed vertically, even when the output device and the injection molding machine move relative to each other. The output device or the injection molding machine may perform control to reduce the internal pressure of the swivel joint in accordance with the magnitude of the internal pressure. The output device or the injection molding machine may perform control to reduce the pressure when the molten resin is output from the output port. The output device or the injection molding machine may perform control to control at least one of the output of the molten resin from the output device and the input of the molten resin to the injection molding machine. The output device may calculate the magnitude of the internal pressure based on information detected at the inlet and outlet of the molten resin in the swivel joint. The output port of the output device and the input port of the injection molding machine may be positioned on substantially the same horizontal line in the vertical direction.

[0007] According to the present invention, it is possible to prevent molten resin passing through the piping from leaking from the joint, compared to when a sleeve is provided as a joint for the piping connecting the device that outputs the molten resin and the injection molding machine.

[0008] FIG. 1 is a front view showing a part of the external configuration of a molten resin supply system including a connecting device according to a first embodiment. FIG. 2 is a schematic configuration diagram of an injection molding machine constituting the molten resin supply system. FIG. 3 is a diagram showing how the positional relationship of a swivel joint changes. FIG. 4 is a front view showing a part of the external configuration of a molten resin supply system including a connecting device according to a second embodiment. FIG. 5 is a front view showing a part of the external configuration of a molten resin supply system including a connecting device according to a third embodiment. FIG. 6 is a front view showing a part of the external configuration of a molten resin supply system including a connecting device according to a fourth embodiment. FIG. 7 is a front view showing a part of the external configuration of a molten resin supply system according to a fifth embodiment. FIG. 8 is a plan view showing a part of the external configuration of a molten resin supply system according to the fifth embodiment. FIG. 9 is a plan view showing a part of the external configuration of a molten resin supply system according to a sixth embodiment. FIG. 10 is a front view showing a part of the external configuration of a molten resin supply system according to a seventh embodiment.

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. First Embodiment (Configuration of Molten Resin Supply System) Fig. 1 is a front view showing a part of the external configuration of a molten resin supply system 1 including a connecting device 10 according to a first embodiment. Fig. 2 is a schematic configuration diagram of an injection molding machine 90 constituting the molten resin supply system 1.

[0010] The molten resin supply system 1 shown in FIG. 1 is a system configured to include a connection device 10, a decontamination machine 80, which is an example of an output device that outputs molten resin, and an injection molding machine 90. The connection device 10 is a device consisting of piping that connects the decontamination machine 80, which is located on a first side in a direction in which the decontamination machine 80 and the injection molding machine 90 are connected (hereinafter referred to as the "connection direction"), to the injection molding machine 90, which is located on a second side. Note that the expression "connection direction" does not indicate the strict positional relationship between the decontamination machine 80 and the injection molding machine 90, which are connected by the connection device 10. Hereinafter, the same direction as the connection direction may be referred to as the direction in which the heating cylinder 91 of the injection molding machine 90 moves. The connection device 10 is configured to include pipes 11 to 14, swivel joints 21 to 23, and connecting members 31 and 32, which are connected to form a serpentine-shaped pipe that snakes vertically.

[0011] Pipes 11 to 14 are metal pipes that allow molten resin to pass through and have a circular cross-sectional shape. Of these, pipe 11 is a pipe that has one end connected to connecting member 31 and the other end connected to swivel joint 21. Pipe 11 has a curved shape that allows molten resin flowing from the first side toward the second side in the connection direction to flow to the top side in the vertical direction. Pipe 12 is a pipe that has one end connected to swivel joint 21 and the other end connected to swivel joint 22. Pipe 12 has a serpentine shape that allows molten resin flowing from the bottom side toward the top side in the vertical direction to flow to the second side in the connection direction, the bottom side in the vertical direction, the second side in the connection direction, and the top side in the vertical direction in this order.

[0012] Pipe 13 has one end connected to swivel joint 22 and the other end connected to swivel joint 23. Pipe 13 has a curved shape that allows molten resin flowing from the bottom side to the top side in the vertical direction to flow first to the second side in the coupling direction and then to the bottom side in the vertical direction. Pipe 14 has one end connected to swivel joint 23 and the other end connected to connecting member 32. Pipe 14 has a straight shape that allows molten resin flowing from the top side to the bottom side in the vertical direction to flow directly to the bottom side.

[0013] The swivel joint 21 has its bottom end connected to the pipe 11 and its top end connected to the pipe 12. The swivel joint 21 allows the pipes 11 and 12 to rotate via a rotation axis 401. Here, a swivel joint refers to a joint that rotatably connects multiple pipes. Although not shown, the swivel joint includes a shaft and bearing that allow rotation around the central axis of the connected pipes, a seal member that prevents leakage of fluid (molten resin in this embodiment) passing through the inside, and a grease seal member filled with lubricant grease that maintains smooth rotation of the shaft. A grease nipple may also be provided as a grease supply port. The swivel joint and pipe are connected by fastening them with bolts or the like via a rubber O-ring that serves as a seal member.

[0014] The bearings of the swivel joint are composed of so-called "rolling bearings" that rotate the shaft portion via steel balls or bearings, or so-called "sliding bearings" that directly contact the shaft portion and support the rotation of the shaft portion with a surface. The swivel joints 21 to 23 according to this embodiment use rolling bearings. However, this embodiment allows for switching between rolling bearings and sliding bearings depending on the heat-resistant temperature and endurance pressure inside the swivel joints 21 to 23.

[0015] The sealing member of the swivel joint has a predetermined heat resistance temperature and pressure resistance. The heat resistance temperature and pressure resistance of the sealing member are determined by the physical properties of the resin to be recycled and the pressure (e.g., the amount of molten resin) inside the connecting device 10. For example, if the resin to be recycled is polyethylene terephthalate (PET resin), it is preferable that the sealing member be able to withstand the temperature and pressure at which PET resin is transported in a molten state.

[0016] Specifically, for example, the heat resistance temperature is set to 300 degrees Celsius, which is higher than the melting point temperature of homopolymerized PET resin with a small margin, and the endurance pressure is preferably set to 25 MPa (megapascals), which is a pressure that allows a margin above the pressure that is expected to be required from various conditions including the amount of resin input from the output port 801 of the decontamination machine 80 to the connecting device 10 and output from the connecting device 10 to the input port 911 of the injection molding machine 90.

[0017] When there is a trade-off between the heat resistance temperature and the pressure durability of the seal member, lowering the internal pressure of the swivel joint increases the heat resistance temperature of the seal member, thereby suppressing deterioration of the seal member. Note that a method for lowering the internal pressure of each of the swivel joints 21 to 23 according to this embodiment will be described later. Furthermore, when the resin to be recycled changes, the heat resistance temperature is determined to be the melting point of that resin plus α.

[0018] The swivel joint 22 has a bottom end connected to the pipe 12 and a top end connected to the pipe 13. The swivel joint 22 allows the pipes 12 and 13 to rotate via a rotation axis 402. The swivel joint 22 changes its position in the circumferential direction of the rotation axis 401 of the swivel joint 21 and in the circumferential direction of the rotation axis 403 of the swivel joint 23, which changes its position, in response to a change in the position of the swivel joint 23 in the coupling direction, which will be described later. The change in the position of the swivel joint 22 will be described later with reference to FIG. 3.

[0019] The swivel joint 23 has an upper end connected to the pipe 13 and a lower end connected to the pipe 14. The swivel joint 23 allows the pipes 13 and 14 to rotate via a rotation shaft 403. The swivel joint 23 also changes its position when the heating cylinder 91 of the injection molding machine 90 moves. The movement of the heating cylinder 91 occurs, for example, when the heating cylinder 91 discharges (purges) molten resin, and does not result in the entire injection molding machine 90 moving. The change in position of the swivel joint 23 will be described later with reference to FIG. 3.

[0020] As shown in FIG. 1 , the connecting device 10 according to the first embodiment forms four paths extending vertically. Therefore, four swivel joints can be arranged on each path, but a total of three swivel joints (swivel joints 21 to 23) are arranged. That is, although a swivel joint could be arranged on one of the four paths extending vertically (the path formed by the pipe 12), no swivel joint is intentionally arranged. This is because, although there is no limit to the number of swivel joints that can be arranged, increasing the number of swivel joints makes the piping path more unstable and increases various costs. Therefore, when considering the stability and cost of the piping path, it is preferable to arrange three swivel joints.

[0021] The connecting member 31 is a member for connecting the coupling device 10 to the decontamination machine 80, which will be described later, and is fixed to the decontamination machine 80 with a flange or the like. Specifically, the connecting member 31 has a first end in the coupling direction connected to the output port 801 of the decontamination machine 80, and a second end in the coupling direction connected to the pipe 11. The connecting member 31 and the pipe 11 are connected by sandwiching a rubber O-ring, which serves as a sealing member, between them and fixing them with bolts or the like.

[0022] The connecting member 32 is a member for connecting the coupling device 10 to an injection molding machine 90, which will be described later, and is fixed to the injection molding machine 90 with a flange or the like. Specifically, the top end of the connecting member 32 is connected to the pipe 14, and the bottom end of the connecting member 32 is connected to an input port 911 provided in a heating cylinder 91 of the injection molding machine 90. The connecting member 32 and the pipe 14 are connected by sandwiching a rubber O-ring, which serves as a sealing member, and fastening them with bolts or the like.

[0023] Furthermore, if the connecting device 10 is configured to be able to control a gear pump (not shown) arranged in the decontamination machine 80, the connecting device 10 can reduce the amount of molten resin output from the output port 801 of the decontamination machine 80, thereby lowering the internal pressure of the connecting device 10 and lowering the internal pressure of each of the swivel joints 21 to 23.

[0024] The decontamination machine 80 is a device that uses mechanical recycling (physical regeneration method) or chemical recycling (chemical regeneration method) to decontaminate contaminants contained inside the resin of PET bottles and other materials to be recycled and output them as molten resin. "Mechanical recycling" refers to a series of processes in which resin from collected used PET bottles and other materials is sorted, crushed, and washed to remove surface dirt and foreign matter, and then exposed to high temperatures to melt the resin, which then decontaminates the contaminants remaining inside the resin by diffusing them, for example, into a vacuum inside the decontamination machine 80. "Chemical recycling" refers to a series of processes in which resin from collected used PET bottles and other materials is sorted, chemically decomposed, and repolymerized to decontaminate contaminants.

[0025] As described above, the decontamination machine 80 has an output port 801 for outputting the decontaminated resin as molten resin. The output port 801 is connected to the connection member 31 of the coupling device 10, and the molten resin decontaminated by the decontamination machine 80 is input to the coupling device 10 from the connection member 31 connected to the output port 801.

[0026] Here, the vertical position of the output port 801 of the decontamination machine 80 is fixed so that it is on approximately the same horizontal line as the vertical position of the input port 911 of the injection molding machine 90 in order to suppress the generation of thermal stress in the connecting device 10. The relationship between the vertical position of the output port 801 of the decontamination machine 80 and the vertical position of the input port 911 of the injection molding machine 90 will be explained in comparison with the second embodiment, which will be described later, with reference to FIG. 4 .

[0027] The decontamination machine 80 performs control to reduce the internal pressure of each of the swivel joints 21 to 23 of the coupling device 10 in accordance with the magnitude of the internal pressure of each of the swivel joints 21 to 23. For example, the decontamination machine 80 may control the output of molten resin to the coupling device 10 based on information detected by the connection members 31 and 32, which correspond to the inlet and outlet of the coupling device 10, respectively, to reduce the internal pressure of the coupling device 10 and reduce the internal pressure of each of the swivel joints 21 to 23. Here, examples of the information detected by each of the connection members 31 and 32 include information about the flow rate of the molten resin per unit time (such as the input and output flow rates) detected by a flow sensor (not shown), information about the temperature of the molten resin, and information about the pressure of the molten resin. The pressure of the molten resin can also be determined based on the amount of molten resin inside the coupling device 10, which is determined from the amount of molten resin input and output to and from the coupling device 10.

[0028] Specifically, for example, if the content of the information detected by each of the connecting members 31 and 32 indicates an abnormality (such as an abnormality in pressure or temperature), the decontamination machine 80 may stop the output of molten resin to the coupling device 10 and control the internal pressure of each of the swivel joints 21 to 23 to decrease. Furthermore, for example, if the content of the information detected by each of the connecting members 31 and 32 does not indicate an abnormality but indicates that an abnormality is likely to occur if left as is, even if the information does not indicate an abnormality and is of low urgency, the decontamination machine 80 may control the output of molten resin to the coupling device 10 to decrease the internal pressure of the coupling device 10 and decrease the internal pressure of each of the swivel joints 21 to 23.

[0029] Furthermore, for example, the decontamination machine 80 may control the output of molten resin to the connecting device 10 based on information detected at each of the inlets and outlets for the molten resin in each of the swivel joints 21 to 23, thereby reducing the internal pressure of each of the swivel joints 21 to 23. Here, the information detected at each of the inlets and outlets for the molten resin in each of the swivel joints 21 to 23 may be, for example, information on the flow rate of the molten resin per unit time detected by a flow sensor (not shown). By performing the above-described control, for example, when there is a trade-off between the heat-resistant temperature and the withstand pressure of the sealing members (not shown) of the swivel joints 21 to 23, it is possible to lower the withstand pressure of the sealing members and increase the heat-resistant temperature.

[0030] Specifically, the decontamination machine 80 controls the output of molten resin to the connection device 10, for example, by controlling the pressure when the molten resin is output from the output port 801. In this case, although not shown, the decontamination machine 80 controls a gear pump used to output the molten resin and the amount of resin output from the output port 801, thereby reducing the pressure when the molten resin is output from the output port 801.

[0031] Furthermore, the decontamination machine 80 may control the output (flow rate and pressure) of the molten resin according to the amount of molten resin used in the injection molding machine 90 and the amount of molten resin discharged from the injection molding machine 90. In this case, since it may be difficult to control the output amount of molten resin in a direction to reduce it, for example, when the decontamination machine 80 is operating continuously, a buffer member for temporarily storing excess molten resin or another path for flowing the excess molten resin may be provided. Furthermore, if there is too much excess molten resin, another path for disposal may be used, or the excess molten resin may be connected to the input port of another injection molding machine so that it can be supplied.

[0032] In addition, if the decontamination machine 80 can control the production volume of molded products (e.g., products, product preforms) produced by the injection molding machine 90, the decontamination machine 80 may control the output (flow rate and pressure) of molten resin from the output port 801 by increasing the production volume of molded products produced by the injection molding machine 90.

[0033] The injection molding machine 90 is a molding machine used to manufacture molded articles using molten resin as a material. The injection molding machine 90 is connected to the decontamination machine 80 via a connecting device 10, allowing it to receive molten resin output from the decontamination machine 80 and manufacture molded articles using the molten resin as a material. As shown in FIG. 2 , the injection molding machine 90 is configured to include a heating cylinder 91, an injection cylinder 92, and a mold 93. The injection molding machine 90 is a so-called pre-plunger type (also called a pre-plasticizer type) injection molding machine that combines an independent heating cylinder 91 and an injection cylinder 92. Therefore, the longitudinal axis of the heating cylinder 91 and the longitudinal axis of the injection cylinder 92 (i.e., the connection direction) are not coaxial.

[0034] The heating cylinder 91 heats the molten resin used to make the molded product and delivers the required amount of molten resin to the injection cylinder 92. The heating cylinder 91 includes an input port 911 for inputting the molten resin, a screw 912 for heating the input molten resin, and an output port 913 for outputting the heated molten resin. The heating cylinder 91 heats the molten resin using shear heat generated by the rotation of the screw 912 and heat from a band heater (not shown), and outputs the molten resin from the output port 913 toward the injection cylinder 92. The band heater is, for example, a lightweight, thin, cylindrical heater made of nichrome wire insulated with heat-resistant mica plates and sheathed in stainless steel. The band heater has a smooth inner surface that contacts the piping, allowing it to be easily attached to the cylindrical piping.

[0035] The injection cylinder 92 is a cylinder that injects molten resin toward the inside of the mold 93. The injection cylinder 92 is configured to include an input port 921 for inputting the molten resin output from the output port 913 of the heating cylinder 91, a plunger 922 that pressurizes the input molten resin toward the second side in the connection direction, and an injection port 923 that injects the pressurized molten resin into the inside of the mold 93. The mold 93 molds the molten resin by opening and closing the mold, and cools and solidifies it to complete a molded product (for example, a product, a preform for a product).

[0036] The injection molding machine 90 performs control to reduce the internal pressure of each of the swivel joints 21 to 23 of the connecting device 10 in accordance with the magnitude of the internal pressure of each of the swivel joints 21 to 23. For example, the injection molding machine 90 may control the input of molten resin output from the connecting device 10 based on information detected by each of the connecting members 31 and 32 of the connecting device 10, thereby reducing the internal pressure of the connecting device 10 and the internal pressure of each of the swivel joints 21 to 23. Here, examples of the information detected by each of the connecting members 31 and 32 include information on the flow rate of the molten resin per unit time (such as the input and output flow rate) detected by a flow sensor (not shown), information on the temperature of the molten resin, and information on the pressure of the molten resin. The pressure of the molten resin can also be determined based on the amount of molten resin inside the connecting device 10, which is determined from the amount of molten resin input and output to the connecting device 10.

[0037] Specifically, for example, if the content of the information detected by each of the connecting members 31 and 32 indicates an abnormality (such as an abnormality in pressure or temperature), the injection molding machine 90 may increase the flow rate when output from the coupling device 10 and input to the injection molding machine 90, thereby reducing the internal pressure of the coupling device 10 and reducing the internal pressure of each of the swivel joints 21 to 23. Furthermore, for example, if the content of the information detected by each of the connecting members 31 and 32 does not indicate an abnormality but indicates a tendency for an abnormality to occur if left as is, even if the information does not indicate an abnormality but is of low urgency, the injection molding machine 90 may increase the flow rate when output from the coupling device 10 and input to the injection molding machine 90, thereby reducing the internal pressure of the coupling device 10 and reducing the internal pressure of each of the swivel joints 21 to 23.

[0038] Furthermore, for example, the injection molding machine 90 may control the input of molten resin output from the connecting device 10 based on information detected at each of the inlet and outlet of the molten resin in each of the swivel joints 21 to 23, thereby lowering the internal pressure of the connecting device 10 and lowering the internal pressure of each of the swivel joints 21 to 23. Here, the information detected at each of the inlet and outlet of the molten resin in each of the swivel joints 21 to 23 may be, for example, information about the flow rate of the molten resin per unit time detected by a flow sensor (not shown).

[0039] The injection molding machine 90 controls the input of the molten resin output from the connecting device 10, for example, by controlling the flow rate of the molten resin input to the input port 911. In this case, the injection molding machine 90 controls the operation of a screw 912 or a plunger 922, which are disposed downstream of the input port 911 and are used for transporting the molten resin, to form a free space downstream and allow the molten resin to escape there. This increases the flow rate of the molten resin input to the input port 911, thereby reducing the internal pressure of the connecting device 10 and the internal pressure of each of the swivel joints 21 to 23.

[0040] Furthermore, if the injection molding machine 90 is configured to be able to control a gear pump (not shown) arranged in the decontamination machine 80, the injection molding machine 90 can reduce the amount of molten resin output from the output port 801 of the decontamination machine 80, thereby lowering the internal pressure of the connecting device 10 and lowering the internal pressure of each of the swivel joints 21 to 23.

[0041] (Positional Relationship of Swivel Joints) Figure 3 is a diagram showing how the positional relationship of the swivel joints 21 to 23 changes. Figure 3 shows how the positional relationship of the swivel joints 21 to 23 shown in Figure 2 changes when viewed from the top to the bottom in the vertical direction. The positional relationship of the swivel joints 21 to 23 shown in solid lines shows an example of the positional relationship during normal operation of the injection molding machine 90 (see Figure 2). In contrast, the positional relationship between the swivel joint 21 shown in solid lines and the swivel joints 22 and 23 shown in dashed lines shows an example of the positional relationship when the position of the heating cylinder 91 of the injection molding machine 90 moves. As described above, it is assumed that the position of the output port 801 (see Figure 1) of the decontamination machine 80 is fixed, and therefore the position of the swivel joint 21 is also fixed.

[0042] As shown in FIG. 3, the positional relationship of the swivel joints 21 to 23 during normal operation of the injection molding machine 90 is such that the rotation axis 402 of the swivel joint 22, shown by a solid line, is positioned rearward in the fore-and-aft direction from an imaginary line 700 connecting the rotation axis 401 of the swivel joint 21 and the rotation axis 403 of the swivel joint 23, shown by a solid line.

[0043] At this time, the position of swivel joint 23 indicated by the solid line is the position closest to the second side in the coupling direction within its movable range, but even at this position, rotation axis 402 of swivel joint 22 is not positioned on imaginary line 700. Specifically, coupling device 10 is configured so that the sum of the length of imaginary line 701 connecting rotation axis 401 of swivel joint 21 and rotation axis 402 of swivel joint 22 and the length of imaginary line 702 connecting rotation axis 402 of swivel joint 22 and rotation axis 403 of swivel joint 23 is longer than the length of imaginary line 700.

[0044] The length of the imaginary straight line 700 is determined based on conditions such as the installation position of the injection molding machine 90 and the range of movement of the position of the heating cylinder 91. The length of the imaginary straight line 701 is determined based on conditions such as the shape and length of the pipe 12 (see FIG. 1). The length of the imaginary straight line 702 is determined based on conditions such as the shape and length of the pipe 13 (see FIG. 1). When designing the connecting device 10, the above conditions are taken into consideration so that the sum of the lengths of the imaginary straight lines 701 and 702 is longer than the length of the imaginary straight line 700.

[0045] That is, when the position of the heating cylinder 91 of the injection molding machine 90 moves, the connecting device 10 repeats an action of extending in the connecting direction (an action of being pulled toward the second side) and an action of contracting in the connecting direction (an action of being pushed toward the first side) in response to the movement. When these actions are viewed from the top to the bottom in the up-to-down direction, as shown in Figure 3, for example, the rotation axis 402 of the swivel joint 22 rotates clockwise when the connecting device 10 extends in the connecting direction, and rotates counterclockwise when the connecting device 10 contracts in the connecting direction.

[0046] Assume now that the coupling device 10 is configured so that it forms a straight line in the coupling direction (i.e., the imaginary lines 701 and 702 are a single straight line when viewed from the top-bottom direction). In this case, when the rotation shaft 403 of the swivel joint 23 attempts to move toward the first side, either a force that rotates the rotation shaft 402 of the swivel joint 22 counterclockwise or a force that rotates it clockwise is applied. As a result, the rotation shaft 402 of the swivel joint 22 rotates unpredictably in either the counterclockwise or clockwise direction, causing the trajectory of the piping to become unstable. It is also possible to configure the imaginary lines 701 and 702 to form a single straight line when viewed from the top-bottom direction, while providing a stopper to prevent the rotation shaft 402 from rotating clockwise. However, this would impose loads on the stopper, the rotation shaft, the piping, etc. For this reason, it is preferable that the connecting device 10 be configured so that the imaginary lines 701 and 702 do not form a single straight line when viewed from the top-bottom direction, even if the decontamination machine 80 and the injection molding machine 90 move relative to each other.

[0047] As an example of such a configuration, an upper limit in terms of movement control may be set for the amount of movement of the position of heating cylinder 91, or the component dimensions of injection molding machine 90 may be determined so that when the position of rotation shaft 403 of swivel joint 22 moves in the coupling direction, the sum of the lengths of imaginary straight lines 701 and 702 is always longer than the length of imaginary straight line 700. Specifically, for example, an upper limit in terms of movement control may be set, or the component dimensions may be determined so that when heating cylinder 91 is moved to the utmost side in the coupling direction, the sum of the lengths of imaginary straight lines 701 and 702 is always longer than the length of imaginary straight line 700.

[0048] Also, for example, a member that serves as a stopper may be provided to prevent rotation axis 402 of swivel joint 22 from being positioned on virtual straight line 700. Furthermore, as a process for preventing rotation axis 402 of swivel joint 22 from being positioned on virtual straight line 700, the position of rotation axis 402 of swivel joint 22 may be detected, and when rotation axis 402 of swivel joint 22 approaches virtual straight line 700, a warning message, sound, or the like may be output, or the operation of the system may be stopped.

[0049] Furthermore, if rotation axis 402 of swivel joint 22 is positioned on imaginary straight line 700, when swivel joint 23 moves toward the first side in the coupling direction, no force is applied that tends to move swivel joint 22 in the forward / backward direction, and instead a force (offset load) that tends to move swivel joint 22 toward the first side in the coupling direction may be applied. For this reason, the relationship among the lengths of imaginary straight lines 700, 701, and 702 is taken into consideration so that rotation axis 402 of swivel joint 22 is not positioned on imaginary straight line 700.

[0050] When the position of the heating cylinder 91 (see FIGS. 1 and 2) of the injection molding machine 90 moves toward the first side in the coupling direction, the connecting member 32 (see FIG. 1) and the swivel joint 23 move toward the first side in the coupling direction. Specifically, as shown in FIG. 3, the swivel joint 23 shown in solid line moves in the direction of the arrow to the position of the swivel joint 23 shown in dashed line. Then, the swivel joint 22 moves counterclockwise around the circumference of the swivel joint 21. Specifically, as shown in FIG. 3, the swivel joint 22 shown in solid line moves in the direction of the arrow to the position of the swivel joint 22 shown in dashed line.

[0051] As a result, imaginary line 701 moves to the position of imaginary line 703, and imaginary line 702 moves to the position of imaginary line 704. Note that the large dashed circle shown in Figure 3 represents the circumferential direction of swivel joint 21 and does not indicate the movable range of swivel joint 22. The movable range of swivel joint 22 is determined by the movable range of swivel joint 23, the distance between swivel joint 21 and swivel joint 22, the distance between swivel joint 22 and swivel joint 23, etc.

[0052] In summary, the coupling device according to the first embodiment of the present invention only needs to have the following configuration, and various embodiments are possible. That is, the coupling device 10 according to the first embodiment is a coupling device that couples a decontamination machine 80 that outputs molten resin to be recycled from an output port, and an injection molding machine 90 that has an input port 911 for inputting the output molten resin, a heating cylinder 91 that heats the molten resin, and an injection cylinder 92 that is independent of the heating cylinder 91 and injects the heated molten resin into a mold 93, and connects the decontamination machine 80 and the injection molding machine 90 by connecting one end of a piping formed by pipes 11 to 14 through which the molten resin passes and swivel joints 21 to 23 to the output port 801 by a connecting member 31 and connecting the other end to the input port 911 by a connecting member 32.

[0053] As a result, one end of the piping formed by the pipes 11 to 14 through which the molten resin passes and the swivel joints 21 to 23 is connected to the output port 801 of the decontamination machine 80 via the connecting member 31, and the other end of the piping is connected to the input port 911 of the injection molding machine 90 via the connecting member 32, thereby connecting the decontamination machine 80 and the injection molding machine 90. In this way, when the swivel joints 21 to 23 are used as joints for the pipes through which the molten resin passes, the sleeve does not slide and move back and forth between the inside and outside of the pipe as in the case where a sleeve is provided as a joint, and therefore the molten resin passing through the pipe is prevented from leaking from the joints.

[0054] Here, the number of swivel joints provided in the connecting device 10 may be three. As a result, the number of swivel joints provided in the connecting device 10 that serve as pipe joints is three (for example, swivel joints 21 to 23), and therefore the trajectory of the pipe changes more flexibly in response to movement of the position of the heating cylinder 91 of the injection molding machine 90 than when, for example, the number of swivel joints is one or two. Furthermore, the trajectory of the pipe can be more stable than when the number of swivel joints is four or more, and various costs (such as procurement costs, maintenance costs, and adjustment costs for the swivel joints) can be reduced.

[0055] Furthermore, the swivel joints 21 to 23 may have sealing members with predetermined heat resistance temperatures and pressure resistances. This allows the sealing members of the swivel joints 21 to 23 to have the predetermined heat resistance temperatures and pressure resistances. The heat resistance temperatures and pressure resistances of the sealing members are determined based on the physical properties of the resin to be recycled and the pressure inside the connecting device 10 (e.g., the amount of molten resin). For example, the temperature and pressure at which the resin to be recycled can be transported in a molten state are determined as the heat resistance temperatures and pressure resistances. If there is a trade-off between the heat resistance temperatures and pressure resistances of the sealing members, lowering the internal pressure of the swivel joint increases the heat resistance temperature of the sealing members. As a result, deterioration of the sealing members of the swivel joints 21 to 23 can be suppressed.

[0056] The connecting device 10 may also heat the molten resin passing through the piping formed by the pipes 11 to 14 and the swivel joints 21 to 23. In this manner, the connecting device 10 heats the molten resin passing through the piping. The heating temperature is preferably a temperature that matches the temperature of the resin to be recycled passing through the piping, and more preferably a temperature that is higher than the melting point of the resin to be recycled passing through the piping but lower than the heat resistance temperature of the sealing members of the swivel joints 21 to 23. Heating the piping includes overheating to maintain the temperature of the piping within a predetermined range. As a result, the molten resin output from the decontamination machine 80 is prevented from cooling and solidifying before being input to the injection molding machine 90. Furthermore, since the molten resin is input to the heating cylinder 91 at a high temperature, energy savings can be achieved during heating by the heating cylinder 91.

[0057] The connecting device 10 may also heat the pipes using a band heater. A band heater is a lightweight, thin, cylindrical heater with a smooth inner surface that contacts the pipe, making it easy to attach to the cylindrical pipe in close contact with it. As a result, the pipes can be heated efficiently.

[0058] Furthermore, the swivel joints 21 to 23 may use plain bearings to rotate the tubes 12 and 13, and may use part of the molten resin as a lubricant for the plain bearings. In this way, when the swivel joints 21 to 23 use plain bearings to rotate the tubes, part of the molten resin passing through the interiors of the swivel joints 21 to 23 is used as a lubricant. As a result, there is no need to prepare a separate lubricant, and mixing of the separately prepared lubricant into the molten resin can be suppressed.

[0059] Furthermore, the molten resin supply system according to the first embodiment of the present invention only needs to have the following configuration, and various embodiments are possible. That is, the molten resin supply system 1 according to the first embodiment is a molten resin supply system including a decontamination machine 80, an injection molding machine 90, and a coupling device 10, in which the output port 801 of the decontamination machine 80 is fixed in position, and the input port 911 of the heating cylinder 91 moves in position in accordance with the movement of the heating cylinder 91. As a result, even if the position of the output port 801 of the decontamination machine 80 is fixed and the position of the input port 911 of the heating cylinder 91 moves, the swivel joints 21 to 23 serving as joints allow the trajectory of the piping to flexibly change. As a result, compared to when a sleeve is used as a joint for the piping connecting the decontamination machine and the injection molding machine, leakage of molten resin passing through the piping from the joints is suppressed.

[0060] The molten resin supply system 1 also includes a decontamination machine 80, an injection molding machine 90, and a connecting device 10, and is characterized in that even if the decontamination machine 80 and the injection molding machine 90 move relative to each other, imaginary lines 701 and 702 connecting the rotation axes 401 to 403 of the three swivel joints 21 to 23 connected via the two pipes 12 and 13 of the connecting device 10 do not form a single straight line when viewed from the top-to-bottom direction, or a process is performed to prevent the imaginary lines 701 and 702 from forming a single straight line when viewed from the top-to-bottom direction. This prevents the imaginary lines 701 and 702 connecting the rotation axes 401 to 403 of the three swivel joints 21 to 23 connected via the two pipes 12 and 13 from forming a single straight line when viewed from the top-to-bottom direction. As a result, the trajectory of the piping can be stabilized compared to when the imaginary lines 701 and 702 connecting the rotation axes 401 to 403 of the three swivel joints 21 to 23 form a single straight line when viewed from the top to bottom.

[0061] Here, the decontamination machine 80 or the injection molding machine 90 may perform control to reduce the internal pressure of each of the swivel joints 21 to 23 depending on the magnitude of the internal pressure of each of the swivel joints 21 to 23. For example, as described above, the decontamination machine 80 can reduce the internal pressure of the coupling device 10 and the internal pressure of each of the swivel joints 21 to 23 by reducing the output of molten resin to the coupling device 10 based on information detected at each of the connecting members 31 and 32 and information detected at each of the molten resin inlets and outlets of each of the swivel joints 21 to 23. Furthermore, the decontamination machine 80 can reduce the internal pressure of the coupling device 10 and the internal pressure of each of the swivel joints 21 to 23 by reducing the output of molten resin to the coupling device 10 based on the amount of molten resin used in the injection molding machine 90 and the amount of molten resin discharged from the injection molding machine 90. Furthermore, injection molding machine 90 can reduce the internal pressure of connecting device 10 and each of swivel joints 21 to 23 by increasing the input of molten resin output from connecting device 10 based on information detected at each of connecting members 31 and 32 and information detected at the inlet and outlet of the molten resin in each of swivel joints 21 to 23. As a result, when there is a trade-off between the heat resistance temperature and endurance pressure of the seal members (not shown) of swivel joints 21 to 23, it is possible to reduce the endurance pressure of the seal members and increase the heat resistance temperature, thereby suppressing deterioration of the seal members.

[0062] Furthermore, the decontamination machine 80 or the injection molding machine 90 may perform control to reduce the pressure when molten resin is output from the output port 801 of the decontamination machine 80, as control to reduce the internal pressure of each of the swivel joints 21 to 23. Thereby, control to reduce the pressure when molten resin is output from the output port 801 of the decontamination machine 80 is performed, as control to reduce the internal pressure of the swivel joints 21 to 23. As a result, when there is a trade-off between the heat-resistant temperature and endurance pressure of the sealing members of the swivel joints 21 to 23, it is possible to lower the endurance pressure of the sealing members and increase the heat-resistant temperature, thereby suppressing deterioration of the sealing members.

[0063] Furthermore, the decontamination machine 80 or the injection molding machine 90 may control at least one of the output of the molten resin from the decontamination machine 80 and the input of the molten resin to the injection molding machine 90 to reduce the pressure when the molten resin is output from the output port 801. This controls the output of the molten resin from the decontamination machine 80 and the input of the molten resin to the injection molding machine 90. As a result, the internal pressure of the connection device 10 can be reduced, and the internal pressure of each of the swivel joints 21 to 23 can be reduced. Therefore, for example, when there is a trade-off between the heat resistance temperature and the endurance pressure of the sealing members of each of the swivel joints 21 to 23, the endurance pressure of the sealing members can be reduced and the heat resistance temperature can be increased, thereby suppressing deterioration of the sealing members.

[0064] Furthermore, the decontamination machine 80 or the injection molding machine 90 may calculate the magnitude of the internal pressure of each of the swivel joints 21 to 23 based on information detected at the inlet and outlet for the molten resin in each of the swivel joints 21 to 23. This allows the magnitude of the internal pressure of the swivel joint to be calculated based on information about the molten resin detected at the inlet and outlet for the molten resin in each of the swivel joints 21 to 23. As a result, it becomes possible to control the internal pressure of each of the swivel joints 21 to 23 based on the calculated value.

[0065] Furthermore, the vertical positions of the output port 801 of the decontamination machine 80 and the input port 911 of the injection molding machine 90 may be on approximately the same horizontal line. This allows the vertical positions of the output port 801 of the decontamination machine 80 and the input port 911 of the injection molding machine 90 to be on approximately the same horizontal line, thereby suppressing thermal stress caused by thermal expansion of the piping. As a result, damage to the piping caused by thermal stress can be suppressed compared to when the vertical positions of the output port of the decontamination machine and the input port of the injection molding machine are not on approximately the same horizontal line (for example, the coupling device 20 according to the second embodiment described below). The relationship between the vertical positions of the output port 801 of the decontamination machine 80 and the vertical positions of the input port 911 of the injection molding machine 90 will be described in comparison with the second embodiment described below with reference to FIG. 4.

[0066] Second Embodiment (Configuration of Molten Resin Supply System) Figure 4 is a front view showing a portion of the external configuration of a molten resin supply system 2 according to a second embodiment. The configuration of the molten resin supply system 2 according to the second embodiment is basically the same as the configuration of the molten resin supply system 1 according to the first embodiment described above. However, as shown in Figures 1 and 4, the vertical position of the output port 801 of the decontamination machine 80 according to the first embodiment is different from the vertical position of the output port 811 of the decontamination machine 81 according to the second embodiment, and therefore the shape of the piping of the coupling device 20 according to the second embodiment is different from the shape of the piping of the coupling device 10 according to the first embodiment.

[0067] The configuration of the coupling device 20 according to the second embodiment is as follows. That is, as shown in Fig. 4, the coupling device 20 is a device consisting of piping that couples a decontamination machine 81 arranged on a first side in the coupling direction to an injection molding machine 90 arranged on a second side. The coupling device 20 is composed of pipes 41 to 44, swivel joints 51 to 53, and connecting members 61 and 62, which are connected to form a serpentine-shaped pipe.

[0068] Pipes 41 to 44 are metal pipes through which molten resin passes. Of these, pipe 41 is a pipe having one end connected to connecting member 61 and the other end connected to swivel joint 51. Pipe 41 has a curved shape that allows molten resin flowing from the first side toward the second side in the coupling direction to flow to the bottom side in the vertical direction. Pipe 42 is a pipe having one end connected to swivel joint 51 and the other end connected to swivel joint 52. Pipe 42 has a curved shape that allows molten resin flowing from the top side toward the bottom side in the vertical direction to flow to the second side in the coupling direction and then to the top side in the vertical direction.

[0069] Pipe 43 has one end connected to swivel joint 52 and the other end connected to swivel joint 53. Pipe 43 has a curved shape that allows molten resin flowing from the bottom side to the top side in the vertical direction to flow first to the second side in the coupling direction and then to the bottom side in the vertical direction. Pipe 44 has one end connected to swivel joint 53 and the other end connected to connecting member 62. Pipe 44 has a straight shape that allows molten resin flowing from the top side to the bottom side in the vertical direction to flow directly to the bottom side.

[0070] Swivel joint 51 has its top end connected to pipe 41 and its bottom end connected to pipe 42. Swivel joint 51 allows pipes 41 and 42 to rotate via a rotation shaft 71. Swivel joint 52 has its bottom end connected to pipe 42 and its top end connected to pipe 43. Swivel joint 52 allows pipes 42 and 43 to rotate via a rotation shaft 72. Furthermore, swivel joint 52 changes its position in the circumferential direction of rotation shaft 71 of swivel joint 51 and in the circumferential direction of rotation shaft 73 of swivel joint 53, which changes its position, in response to a change in the position of swivel joint 53 in the coupling direction, as described below. The change in position of swivel joint 52 is similar to the change in position of swivel joint 22 in FIG. 3 described above.

[0071] The swivel joint 53 has an upper end connected to the pipe 43 and a lower end connected to the pipe 44. The swivel joint 53 allows the pipes 43 and 44 to rotate via a rotation shaft 73. When the position of the heating cylinder 91 of the injection molding machine 90 moves, the swivel joint 53 changes its position accordingly. The change in position of the swivel joint 53 is similar to the change in position of the swivel joint 23 in FIG. 3 described above.

[0072] The connecting member 61 is a member for connecting the coupling device 20 to the decontamination machine 81, and is fixed to the decontamination machine 81 with a flange or the like. Specifically, the connecting member 61 has a first end in the coupling direction connected to an output port 811 of the decontamination machine 81, and a second end in the coupling direction connected to the pipe 41. The connecting member 62 is a member for connecting the coupling device 20 to the injection molding machine 90, and is fixed to the injection molding machine 90 with a flange or the like. Specifically, the connecting member 62 has an end on the top side in the vertical direction connected to the pipe 44, and a bottom end in the vertical direction connected to an input port 911 provided on the heating cylinder 91 of the injection molding machine 90.

[0073] Comparison Between First and Second Embodiments Similar to the coupling device 10 according to the first embodiment, the coupling device 20 according to the second embodiment prevents molten resin passing through the piping from leaking from the joint, compared to when a sleeve is used as a joint for the piping connecting the decontamination machine and the injection molding machine. However, when comparing the coupling device 10 according to the first embodiment (see FIG. 1 ) with the coupling device 20 according to the second embodiment (see FIG. 4 ), there are differences, for example, in the following points.

[0074] That is, as shown in Fig. 1, the vertical position of the output port 801 of the decontamination machine 80 connected to the connecting device 10 according to the first embodiment is on approximately the same horizontal line as the vertical position of the input port 911 of the injection molding machine 90. In contrast, as shown in Fig. 4, the vertical position of the output port 811 of the decontamination machine 81 connected to the connecting device 20 according to the second embodiment is not on approximately the same horizontal line as the vertical position of the input port 911 of the injection molding machine 90.

[0075] 1 according to the first embodiment, the output port 801 of the decontamination machine 80 connected to the coupling device 10 and the input port 911 of the injection molding machine 90 are located on approximately the same horizontal line, so even if the piping of the coupling device 10 thermally expands when overheated by a band heater or the like, thermal stress is suppressed from occurring in the coupling device 10. This suppresses damage such as breakage to the pipes 11 to 14 that constitute the piping and the bearings of the swivel joints 21 to 23.

[0076] In addition, in the coupling device 10 according to the first embodiment shown in FIG. 1 , the four paths that form the piping and extend in the vertical direction are located on the same vertical side (top side) of the output port 801 and the input port 911. This allows the piping to expand in the same direction when thermally expanding, further reducing the occurrence of thermal stress in the coupling device 10. Specifically, the first side of the coupling device 10 in the coupling direction thermally expands in the vertical direction from the bottom side to the top side, while the second side of the coupling direction thermally expands to the same extent in the vertical direction from the bottom side to the top side. In this case, the occurrence of thermal stress in the coupling device 10 is further reduced, further reducing damage, such as breakage, to the pipes 11 to 14 that form the piping and the bearings of the swivel joints 21 to 23.

[0077] In contrast, in the second embodiment shown in FIG. 4 , the output port 811 of the decontamination machine 81 connected to the coupling device 20 and the input port 911 of the injection molding machine 90 are not located on substantially the same horizontal line, which makes it easy for thermal stress to occur in the coupling device 20. Furthermore, in the coupling device 20 according to the second embodiment shown in FIG. 4 , the three paths extending in the vertical direction that form the piping are not located on the same vertical side of the output port 811 and the input port 911. That is, these three paths are located on the bottom side of the output port 811 and on the top side of the input port 911. Therefore, when the piping of the coupling device 20 overheats, the directions of thermal expansion cannot be aligned. Specifically, the first side of the coupling device 20 in the coupling direction thermally expands from the top to the bottom, while the second side of the coupling direction thermally expands to the same extent from the bottom to the top.

[0078] In this case, thermal stress may occur in the coupling device 20, causing damage such as breakage to the pipes 41 to 44 that make up the piping, and the shafts, bearings, and sealing members of the swivel joints 51 to 53, which may result in leakage of the molten resin flowing inside. For this reason, compared to the configuration of the coupling device 20 according to the second embodiment, the configuration of the coupling device 10 according to the first embodiment, i.e., a configuration in which the output port 801 of the decontamination machine 80 and the input port 911 of the injection molding machine 90 are positioned on approximately the same horizontal line in the vertical direction, is preferable, and a configuration in which the expansion directions of the piping due to thermal expansion due to overheating are the same rather than a configuration in which the expansion directions are opposite. From the above, it can be said that the connecting device 20 according to the second embodiment is a configuration that can be selected when there are restrictions on the relative positions of the decontamination machine 81 and the injection molding machine 90, the position of the output port 811 of the decontamination machine 81, the position of the input port 911 of the injection molding machine 90, etc., and the vertical position of the output port 811 of the decontamination machine 81 and the vertical position of the input port 911 of the injection molding machine 90 cannot be arranged on approximately the same horizontal line.

[0079] 1, even if the output port 801 of the decontamination machine 80 and the input port 911 of the injection molding machine 90 are positioned on substantially the same horizontal line, the directions of thermal expansion of the piping when overheated may not be aligned. Such a configuration will be described below as a third embodiment.

[0080] <Third embodiment> (Configuration of molten resin supply system) Figure 5 is a front view showing a part of the external configuration of a molten resin supply system 3 according to a third embodiment. As shown in Figures 4 and 5, the configuration of the molten resin supply system 3 according to the third embodiment is basically the same as the configuration of the molten resin supply system 2 according to the second embodiment. However, the vertical position of the output port 811 of the decontamination machine 81 according to the second embodiment is different from the vertical position of the output port 821 of the decontamination machine 82 according to the third embodiment. Therefore, the shape of the pipe 42 of the coupling device 20 according to the second embodiment is different from the shape of the pipe 421 of the coupling device 30 according to the third embodiment.

[0081] The configuration of the coupling device 30 according to the third embodiment is as follows. That is, as shown in Fig. 5, the coupling device 30 is a device made up of piping that couples the decontamination machine 82 arranged on the first side in the coupling direction to the injection molding machine 90 arranged on the second side. The coupling device 30 is made up of pipes 41, 421, 43, and 44, swivel joints 51 to 53, and connecting members 61 and 62, which are connected to form a serpentine-shaped pipe.

[0082] Tube 421 is a metal tube through which molten resin passes, with one end connected to swivel joint 51 and the other end connected to swivel joint 52. Tube 421 has a curved shape that allows molten resin flowing from the top to the bottom in the vertical direction to flow first to the second side in the coupling direction and then to the top in the vertical direction, and the portion extending in the vertical direction is particularly long. Note that the configurations of tubes 41, 43, and 44, swivel joints 51 to 53, and connecting members 61 and 62 are similar to the configurations of tubes 41, 43, and 44, swivel joints 51 to 53, and connecting members 61 and 62 in coupling device 20 according to the second embodiment shown in FIG. 4 described above, and therefore will not be described here.

[0083] 4 and 5 , the coupling device 30 according to the third embodiment differs from the coupling device 20 according to the second embodiment in that the vertical position of the output port 821 of the decontamination machine 82 is on approximately the same horizontal line as the vertical position of the input port 911 of the injection molding machine 90. Therefore, when the piping of the coupling device 30 overheats, the portion above the vertical positions of the output port 821 and the input port 911 thermally expands so as to extend upward, and the portion below the vertical positions of the output port 821 and the input port 911 thermally expands so as to extend downward. At this time, the difference between the degree of thermal expansion extending upward and the degree of thermal expansion extending downward is not enough to cause thermal stress in the coupling device 30 and cause damage such as breakage to each part of the piping. In contrast, in the coupling device 20 according to the second embodiment, as shown in Fig. 4, the vertical position of the output port 811 of the decontamination machine 81 is not on substantially the same horizontal line as the vertical position of the input port 911 of the injection molding machine 90, and therefore thermal stress is likely to occur in the coupling device 20. For this reason, the configuration of the third embodiment is preferable to the configuration of the second embodiment.

[0084] 1 and 5 , in the connection device 30 according to the third embodiment, similar to the connection device 10 according to the first embodiment, the vertical position of the output port 821 of the decontamination machine 82 is on approximately the same horizontal line as the vertical position of the input port 911 of the injection molding machine 90. However, unlike the connection device 10 according to the first embodiment, the connection device 30 according to the third embodiment has three vertical paths that form piping, and are not on the same side relative to the vertical positions of the output port 821 and the input port 911. That is, among these three paths, some are on the bottom side and others are on the top side relative to the vertical positions of the output port 821 and the input port 911. Therefore, unlike the connection device 10 according to the first embodiment, the connection device 30 according to the third embodiment cannot align the directions of thermal expansion of the piping.

[0085] Specifically, the piping of the coupling device 30 includes a path extending in the vertical direction and including the swivel joint 51 (hereinafter referred to as the "first path of the third embodiment"), a path extending in the vertical direction and including the swivel joint 52 and the pipe 421 (hereinafter referred to as the "second path of the third embodiment"), and a path extending in the vertical direction and including the swivel joint 53 (hereinafter referred to as the "first path of the third embodiment"). Of these, the first path of the third embodiment is entirely located on the ground side with respect to the vertical positions of the output port 821 and the input port 911, while the third path of the third embodiment is entirely located on the ceiling side with respect to the vertical positions of the output port 821 and the input port 911. Furthermore, the second path of the third embodiment has a portion located on the ceiling side and a portion located on the floor side with respect to the vertical positions of the output port 821 and the input port 911.

[0086] Here, when the piping of the coupling device 30 thermally expands, the portion that is on the ground side relative to the vertical positions of the output port 821 and the input port 911 thermally expands in a direction from the top to the bottom in the vertical direction. In contrast, the portion that is on the top side relative to the vertical positions of the output port 821 and the input port 911 thermally expands in a direction from the bottom to the top in the vertical direction. Here, as described above, the difference in the degree of thermal expansion between the portion of the piping of the coupling device 30 that extends to the top and the portion that extends to the bottom is not such that thermal stress is generated in the piping of the coupling device 30 and damages each part, such as breakage.

[0087] However, the degree of elongation due to thermal expansion may differ between the portion with a swivel joint and the portion without. Regarding this point, among the portions of the piping of the coupling device 30 that extend upward due to thermal expansion, the upper portion of the second path in the third embodiment has a swivel joint 52, and the third path in the third embodiment has a swivel joint 53. Therefore, differences in the degree of elongation due to thermal expansion are unlikely to occur. In contrast, among the portions of the piping of the coupling device 30 that extend downward due to thermal expansion, the first path in the third embodiment has a swivel joint 51, but the lower portion of the second path in the third embodiment does not have a swivel joint. Therefore, differences in the elongation of the piping due to thermal expansion may occur. Hereinafter, such differences will be referred to as "expansion / contraction differences."

[0088] The difference in expansion and contraction of the piping due to the presence or absence of a swivel joint is one of the causes of thermal stress in the connecting device 30, and if the difference in expansion and contraction is large, the swivel joint or the pipe may tilt. The impact of the difference in expansion and contraction due to the presence or absence of a swivel joint on the generation of thermal stress is greater when the thermal expansion directions are not aligned than when the thermal expansion directions are aligned. For these reasons, the first embodiment, in which the thermal expansion directions are aligned, is preferable to the third embodiment, in which the thermal expansion directions are not aligned, in that the impact of the difference in expansion and contraction is smaller.

[0089] As mentioned above, the difference in the expansion and contraction of the piping caused by the presence or absence of a swivel joint is one of the causes of thermal stress. However, depending on the placement of the swivel joint, the effect of the difference in the expansion and contraction of the piping can sometimes be suppressed. Such a configuration will be described below as the fourth embodiment.

[0090] <Fourth embodiment> (Configuration of molten resin supply system) Fig. 6 is a front view showing a part of the external configuration of a molten resin supply system 4 according to a fourth embodiment. As shown in Fig. 1 and Fig. 6, the configuration of the molten resin supply system 4 according to the fourth embodiment is basically the same as the configuration of the molten resin supply system 1 according to the first embodiment described above. However, the arrangement of the swivel joint is different.

[0091] The configuration of the coupling device 40 according to the fourth embodiment is as follows. That is, as shown in Fig. 6, the coupling device 40 is a device made up of piping that couples the decontamination machine 83 arranged on the first side in the coupling direction with the injection molding machine 90 arranged on the second side. The coupling device 40 is made up of pipes 411 to 414, swivel joints 211 to 213, and connecting members 31 and 32, which are connected together to form a serpentine-shaped pipe.

[0092] Tube 411 has one end connected to connecting member 31 and the other end connected to swivel joint 211, and has a configuration similar to that of tube 11 in Fig. 1. That is, tube 411 has a curved shape that allows molten resin flowing from the first side toward the second side in the coupling direction to flow to the top side in the vertical direction. Tube 412 has one end connected to swivel joint 211 and the other end connected to swivel joint 212. Tube 412 has a curved shape that allows molten resin flowing from the bottom side toward the top side in the vertical direction to flow to the second side in the coupling direction and then to the bottom side in the vertical direction.

[0093] Pipe 413 has one end connected to swivel joint 212 and the other end connected to swivel joint 213. Pipe 413 has a curved shape that allows molten resin flowing from the top side to the bottom side in the top-to-bottom direction to flow first to the second side in the coupling direction and then to the top side in the top-to-bottom direction. Pipe 414 has one end connected to swivel joint 213 and the other end connected to connecting member 32. Pipe 414 has a curved shape that allows molten resin flowing from the bottom side to the top side in the top-to-bottom direction to flow first to the second side in the coupling direction and then to the bottom side in the top-to-bottom direction.

[0094] Swivel joint 211 is a swivel joint having a bottom end connected to pipe 411 and a top end connected to pipe 412. Swivel joint 212 is a swivel joint having a top end connected to pipe 412 and a bottom end connected to pipe 413. Swivel joint 213 is a swivel joint having a bottom end connected to pipe 413 and a top end connected to pipe 414. The configurations of connecting members 31 and 32 are similar to the configurations of connecting members 31 and 32 in coupling device 10 according to the first embodiment shown in FIG. 1 described above, and therefore description thereof will be omitted.

[0095] 1 and 6 , in the coupling device 40 according to the fourth embodiment, similar to the coupling device 10 according to the first embodiment, the vertical position of the output port 831 of the decontamination machine 83 is on approximately the same horizontal line as the vertical position of the input port 911 of the injection molding machine 90. Furthermore, in the coupling device 40 according to the fourth embodiment, similar to the coupling device 10 according to the first embodiment, the four paths extending vertically that form the piping are on the same side (the top side) with respect to the vertical positions of the output port 831 and the input port 911. Therefore, the directions of expansion when the piping thermally expand are aligned.

[0096] In addition, the piping of the coupling device 10 according to the first embodiment and the coupling device 40 according to the fourth embodiment both have differences in expansion and contraction depending on whether or not a swivel joint is provided. Specifically, as shown in Fig. 1, the piping of the coupling device 10 according to the first embodiment has a path extending in the vertical direction and including a swivel joint 21 (hereinafter referred to as the "first path of the first embodiment"), a path extending in the vertical direction and made of a pipe 12 (hereinafter referred to as the "second path of the first embodiment"), a path extending in the vertical direction and including a swivel joint 22 (hereinafter referred to as the "third path of the first embodiment"), and a path extending in the vertical direction and including a swivel joint 23 (hereinafter referred to as the "fourth path of the first embodiment").

[0097] In the first embodiment, the first, third, and fourth paths each include a swivel joint 21 to 23, but the second path does not include a swivel joint. Therefore, when the piping thermally expands, a difference in expansion and contraction may occur between the first and second paths of the first embodiment. A difference in expansion and contraction may also occur between the second and third paths of the first embodiment. In contrast, a difference in expansion and contraction is unlikely to occur between the third and fourth paths of the first embodiment. In other words, when thermal expansion occurs in the piping of the connection device 10 according to the first embodiment, depending on the magnitude of the difference in expansion and contraction, thermal stress may occur, causing the swivel joints 21 and 22 arranged in the first and third paths of the first embodiment to tilt.

[0098] As shown in FIG. 6, the piping of the connecting device 40 according to the fourth embodiment includes a path extending in the vertical direction and including the swivel joint 211 (hereinafter referred to as the "first path of the fourth embodiment"), a path extending in the vertical direction and including the swivel joint 212 (hereinafter referred to as the "second path of the fourth embodiment"), a path extending in the vertical direction and including the swivel joint 213 (hereinafter referred to as the "third path of the fourth embodiment"), and a path extending in the vertical direction and consisting of the pipe 414 (hereinafter referred to as the "fourth path of the fourth embodiment").

[0099] In the fourth embodiment, the first to third paths each include a swivel joint 211 to 213, but the fourth path does not include a swivel joint. Therefore, when the piping thermally expands, a difference in expansion and contraction may occur between the third path and the fourth path in the fourth embodiment, but a difference in expansion and contraction is unlikely to occur between the first path and the second path in the fourth embodiment. Also, a difference in expansion and contraction is unlikely to occur between the second path and the third path in the fourth embodiment. In other words, when thermal expansion occurs in the piping of the coupling device 40 according to the fourth embodiment, depending on the magnitude of the difference in expansion and contraction, thermal stress may occur, which may cause the swivel joint 213 arranged in the third path in the fourth embodiment to tilt.

[0100] As described above, when adjacent paths in the piping are a combination of paths with swivel joints and paths without swivel joints, differential expansion and contraction is likely to occur. In contrast, when adjacent paths in the piping are a combination of paths with swivel joints or a combination of paths without swivel joints (not shown), differential expansion and contraction is unlikely to occur. Comparing the first embodiment and the fourth embodiment in this regard, the fourth embodiment, which has one combination of paths with swivel joints and paths without swivel joints, is preferable to the first embodiment, which has two combinations of paths with swivel joints and paths without swivel joints.

[0101] 7 and 8 are diagrams showing a part of the external configuration of a molten resin supply system 5 according to a fifth embodiment. Fig. 7 shows a front view of a part of the molten resin supply system 5 as viewed from the front to the rear in the front-to-rear direction. Fig. 8 shows a plan view of the molten resin supply system 5 as viewed from the top to the bottom in the top-to-bottom direction.

[0102] The configuration of the molten resin supply system 5 according to the fifth embodiment is basically the same as the configuration of the molten resin supply systems 1 to 4 according to the above-described embodiments, but the orientation of the output port (and connecting member) of the decontamination machine and the orientation of the rotation axis of the swivel joint are different. That is, the orientation of the output port (and connecting member) of the decontamination machine of the molten resin supply systems 1 to 4 according to the above-described embodiments is such that molten resin is output from the first side toward the second side in the coupling direction. Furthermore, the orientation of the rotation axis of the swivel joint of the coupling device of the molten resin supply systems 1 to 4 according to the above-described embodiments is approximately parallel to the vertical direction.

[0103] In contrast, in the molten resin supply system 5 according to the fifth embodiment, the direction of the output port 841 (and the connecting member 511) of the decontamination machine 84 is such that the molten resin is output from the bottom to the top in the vertical direction. Furthermore, the directions of the rotation axes 711 to 713 of the swivel joints 311 to 313 of the connecting device 50 are not parallel to the vertical direction, but are substantially perpendicular to the direction in which the heating cylinder moves (the connecting direction), i.e., substantially parallel to the front-to-rear direction.

[0104] The specific configuration of the connecting device 50 of the molten resin supply system 5 according to the fifth embodiment is as follows. That is, as shown in Figures 7 and 8, the connecting device 50 is a device made up of piping that connects the decontamination machine 84 arranged on the first side in the connecting direction to the injection molding machine 90 arranged on the second side. The connecting device 50 is made up of pipes 611 to 614, swivel joints 311 to 313, and connecting members 511 and 512, which are connected to form a serpentine-shaped pipe.

[0105] The pipe 611 has one end connected to the connecting member 511 and the other end connected to the swivel joint 311. That is, the pipe 611 has a curved shape that allows the molten resin output from the output port 841 of the decontamination machine 84 to flow toward the swivel joint 311. The pipe 612 has one end connected to the swivel joint 311 and the other end connected to the swivel joint 312. The pipe 612 has a curved shape that allows the molten resin flowing from the swivel joint 311 to flow toward the swivel joint 312.

[0106] Pipe 613 has one end connected to swivel joint 312 and the other end connected to swivel joint 313. Pipe 613 has a curved shape that allows the molten resin flowing from swivel joint 312 to flow toward swivel joint 313. Pipe 614 has a curved shape that allows the molten resin flowing from swivel joint 313 to flow toward input port 911 of heating cylinder 91.

[0107] The swivel joint 311 is a swivel joint having a rear end in the front-to-rear direction connected to the pipe 611 and a front end connected to the pipe 612. The swivel joint 312 is a swivel joint having a front end in the front-to-rear direction connected to the pipe 612 and a rear end connected to the pipe 613. The swivel joint 313 is a swivel joint having a rear end in the front-to-rear direction connected to the pipe 613 and a front end connected to the pipe 614. The configurations of the connecting members 511 and 512 are the same as those shown in the first to fourth embodiments described above, and therefore description thereof will be omitted.

[0108] Comparison of the First to Fourth Embodiments with the Fifth Embodiment As described above, in the coupling devices of the molten resin supply systems according to the first to fourth embodiments, the orientation of the rotation axes of the swivel joints is generally parallel to the vertical direction. In contrast, in the coupling device 50 of the molten resin supply system 5 according to the fifth embodiment, the orientation of each of the rotation axes 711 to 713 of the swivel joints 311 to 313 is not parallel to the vertical direction and is generally parallel to the front-rear direction.

[0109] Due to the difference in the orientation of the rotation axis of the swivel joint as described above, the coupling device 50 of the molten resin supply system 5 according to the fifth embodiment has the following advantages over the coupling devices of the molten resin supply systems according to the first to fourth embodiments. That is, regardless of the embodiment, the coupling device will have manufacturing errors, and these manufacturing errors can cause a bending moment to be applied inside the swivel joint. If a bending moment is applied inside the swivel joint, it can lead to a decrease in the durability of the swivel joint or damage to the swivel joint.

[0110] Examples of manufacturing errors in the coupling device include variations in the vertical length of the pipes that make up the coupling device, axial misalignment of the swivel joints that make up the coupling device, and vertical misalignment between one end of the piping that makes up the coupling device. While methods for suppressing these manufacturing errors include improving the accuracy of each process during manufacturing, this increases manufacturing costs. Furthermore, there are limits to how much accuracy can be improved. In contrast, the coupling device 50 of the molten resin supply system 5 according to the fifth embodiment can absorb the manufacturing errors by rotating the swivel joints 311 to 313, even if the manufacturing errors described above occur.

[0111] That is, manufacturing errors may occur, such as variations in the lengths D1 to D4 of the pipes 611 to 613, axial misalignment (angles θ1 and θ2) of the swivel joints 311 and 313, and misalignment (distance H) between one end of the pipe and the other end in the vertical direction. However, these manufacturing errors are absorbed by the rotation of the swivel joints 311 to 313.

[0112] In this way, according to the connecting device 50 of the fifth embodiment, it is possible to reduce manufacturing costs compared to improving the accuracy of each process during manufacturing, while solving the problem of manufacturing errors that cause bending moments to be applied inside the swivel joints 311 to 313.

[0113] In summary, the coupling device according to the fifth embodiment of the present invention only needs to have the following configuration, and various embodiments are possible. That is, coupling device 50 of molten resin supply system 5 according to the fifth embodiment is a coupling device that couples decontamination machine 84 that outputs molten resin to be recycled from output port 841, and injection molding machine 90 that has input port 911 for inputting the output molten resin, heating cylinder 91 that heats the molten resin, and injection cylinder 92 (see FIG. 2 ) that is independent of heating cylinder 91 and injects the heated molten resin into mold 93 (see FIG. 2 ), and one end of piping formed by pipes 611 to 614 through which the molten resin passes and swivel joints 311 to 313 is connected to output port 841 by connecting member 511, and the other end is connected to input port 911 by connecting member 512, thereby coupling decontamination machine 84 and injection molding machine 90.

[0114] Here, the orientation of each of the rotation axes 711 to 713 of the swivel joints 311 to 313 may be not parallel to the vertical direction, but may be substantially perpendicular (substantially parallel to the front-to-rear direction) to the direction in which the heating cylinder 91 moves (the coupling direction). As a result, even if a manufacturing error occurs in the members that make up the piping of the coupling device 50, the manufacturing error can be absorbed by the rotation of the swivel joints 311 to 313.

[0115] Sixth Embodiment (Configuration of Molten Resin Supply System) Fig. 9 is a diagram showing a part of the external configuration of a molten resin supply system 6 according to a sixth embodiment. Fig. 9 shows a plan view of the molten resin supply system 6 as seen from the top to the bottom in the vertical direction.

[0116] The configuration of the connecting device 60 of the molten resin supply system 6 according to the sixth embodiment is basically the same as the configuration of the connecting device 50 of the molten resin supply system 5 according to the fifth embodiment described above, except for the lengths of some of the pipes, the positional relationship between one end and the other end of the piping, and the positional relationship between the three swivel joints.

[0117] The specific configuration of the coupling device 60 according to the sixth embodiment is as follows. That is, as shown in Fig. 9, the coupling device 60 is a device including piping that couples the decontamination machine 85 arranged on the first side in the coupling direction with the injection molding machine 90 arranged on the second side. The coupling device 60 is composed of pipes 611, 614, 622, and 623, swivel joints 311 to 313, and connecting members 511 and 512, which are coupled together to form a serpentine-shaped pipe.

[0118] Furthermore, an imaginary line L1 connecting one end of the piping to the other end is substantially parallel to the direction (connection direction) in which the heating cylinder 91 moves. Furthermore, the imaginary line L1 is substantially perpendicular to each of the rotation axes 711 to 713 of the swivel joints 311 to 313. Furthermore, an imaginary line L2 connecting the swivel joints 311 to 313 is not parallel to the imaginary line L1 (i.e., not parallel to the connection direction).

[0119] In the connecting device of each embodiment, the section of the piping including the swivel joint arranged on the first side in the connecting direction is referred to as the first piping section, the section including the swivel joint arranged on the second side in the connecting direction is referred to as the third piping section, and the section including the swivel joint arranged between the first and third piping sections is referred to as the second piping section.

[0120] In the piping of the connecting device 60 according to the sixth embodiment, the length D11 in the front-rear direction of the first piping section including the swivel joint 311 is shorter than the length D12 in the front-rear direction of the second piping section including the swivel joint 312. The length D13 in the front-rear direction of the third piping section including the swivel joint 313 is also shorter than the length D12 in the front-rear direction of the second piping section. Specifically, the length D11 in the front-rear direction of the first piping section and the length D13 in the third piping section are each preferably 30% or less of the length of the second piping section. Furthermore, considering safety, the length D11 in the front-rear direction of the first piping section and the length D13 in the third piping section are each preferably 20% or less of the length of the second piping section.

[0121] Comparison Between Fifth and Sixth Embodiments Pipe 622 of connecting device 60 of molten resin supply system 6 is longer than pipe 612 of connecting device 50 of molten resin supply system 5. Specifically, the length of the portion of pipe 622 of connecting device 60 of molten resin supply system 6 that constitutes a part of the second piping is longer than the length of the portion of pipe 612 of connecting device 50 of molten resin supply system 5 that constitutes a part of the second piping.

[0122] Furthermore, pipe 623 of connecting device 60 of molten resin supply system 6 is longer than pipe 613 of connecting device 50 of molten resin supply system 5. Specifically, the length of the portion of pipe 623 of connecting device 60 of molten resin supply system 6 that constitutes part of the second piping is longer than the length of the portion of pipe 613 of connecting device 50 of molten resin supply system 5 that constitutes part of the second piping.

[0123] Furthermore, the positional relationship in the front-rear direction of the swivel joints 311 to 313 of the connecting device 60 of the molten resin supply system 6 is different from the positional relationship in the front-rear direction of the swivel joints 311 to 313 of the connecting device 50 of the molten resin supply system 5. Specifically, as shown in Fig. 9, the positional relationship in the front-rear direction of the swivel joints 311 to 313 of the molten resin supply system 6 is such that the imaginary line L2 is not parallel to the imaginary line L1 (i.e., not parallel to the connecting direction). In contrast, the positional relationship in the front-rear direction of the swivel joints 311 to 313 of the molten resin supply system 5 is such that the imaginary line L21 connecting the swivel joints 311 to 313 is approximately parallel to the connecting direction, as shown in Fig. 8.

[0124] The connecting device 60 of the molten resin supply system 6 according to the sixth embodiment having such a configuration has the following advantages over the connecting device 50 of the molten resin supply system 5 according to the fifth embodiment. That is, as shown by the dashed lines in Figures 8 and 9, thermal distortion occurs in the piping of each of the connecting devices 50 and 60 according to each embodiment in the direction of the arrow. If the piping bends due to this thermal distortion, this can cause a bending moment to be applied inside the swivel joint.

[0125] In contrast, in the connecting device 60 according to the sixth embodiment, the relationship between the length D11 of the first piping section in the front-rear direction, the length D12 of the second piping section in the front-rear direction, and the length D13 of the third piping section in the front-rear direction is such that the amount of thermal strain that can be tolerated in the piping is increased. Therefore, the connecting device 60 according to the sixth embodiment is less susceptible to bending of the piping due to thermal strain than the connecting device 50 according to the fifth embodiment.

[0126] In summary, the coupling device according to the sixth embodiment of the present invention only needs to have the following configuration, and various embodiments are possible. That is, coupling device 60 of molten resin supply system 6 according to the sixth embodiment is a coupling device that couples decontamination machine 85 that outputs molten resin to be recycled from output port 851 to injection molding machine 90 that has input port 911 for inputting the output molten resin, heating cylinder 91 that heats the molten resin, and injection cylinder 92 (see FIG. 2 ) that is independent of heating cylinder 91 and injects the heated molten resin into mold 93 (see FIG. 2 ), and that couples decontamination machine 85 to injection molding machine 90 by connecting pipes 611, 614, 622, and 623 through which the molten resin passes and swivel joints 311 to 313, with one end of the piping connected to output port 851 by connecting member 511 and the other end connected to input port 911 by connecting member 512.

[0127] Here, an imaginary straight line L1 connecting one end and the other end of the pipe may be substantially parallel to the direction in which the heating cylinder 91 moves (the connecting direction).

[0128] Furthermore, an imaginary straight line L1 connecting one end of the pipe to the other end may be substantially perpendicular to each of the rotation axes 711 to 713 of the swivel joints 311 to 313, respectively.

[0129] Furthermore, the length D11 of the first piping section including the swivel joint 311 closest to the end connected to the output port 851 and the length D13 of the third piping section including the swivel joint 313 farthest from the end connected to the output port 851 may each be 30% or less of the length D12 of the second piping section including the swivel joint 312 disposed between the first and third piping sections. This makes it easier to absorb thermal strain in the piping, making it less likely for the piping to bend due to thermal strain.

[0130] Seventh Embodiment (Configuration of Molten Resin Supply System) Figures 10(A) and 10(B) are diagrams showing a portion of the external configuration of a molten resin supply system 7 according to a seventh embodiment. Figures 10(A) and 10(B) show front views of the molten resin supply system 7 as viewed from the front to the rear in the front-to-rear direction. Note that Figure 10(A) shows an example in which the position of the output port 861 of the decontamination machine 86 relative to the heating cylinder 91 of the injection molding machine 90 is on the first side in the coupling direction. Figure 10(B) shows an example in which the position of the output port 861 of the decontamination machine 86 relative to the heating cylinder 91 of the injection molding machine 90 is on the second side in the coupling direction.

[0131] The specific configuration of the coupling device 70 according to the seventh embodiment is as follows. That is, as shown in Figures 10(A) and 10(B), the coupling device 70 is a device made up of piping that connects the output port 861 of the decontamination machine 86 located on the top side in the vertical direction to the injection molding machine 90 located on the bottom side. The coupling device 70 is made up of pipes 631, 632, 633, and 634, swivel joints 311 to 313, and connecting members 512 and 521, which are connected to form a serpentine-shaped piping.

[0132] The configuration of the molten resin supply system 7 according to the seventh embodiment is basically the same as the configuration of each of the molten resin supply systems 5 and 6 according to the fifth and sixth embodiments described above, except that, as described above, the vertical position of the output port 861 of the decontamination machine 86 is different.

[0133] This type of configuration can be adopted, for example, when there are limitations on the space available for arranging the devices as described below. That is, as shown in Figures 10A and 10B, in an injection molding machine 90, it is necessary to arrange a motor 94, etc., on the second side in the coupling direction of a heating cylinder 91, and to arrange a mold 93 on the first side. In this case, it becomes difficult to secure space for arranging a coupling device 70 near the mold 93. Here, for example, if an attempt is made to arrange the output port 861 of a decontamination machine 86 on the lower side in the vertical direction in order to arrange the coupling device 70 near the mold 93, it becomes difficult to secure space for maintenance of the injection molding machine 90.

[0134] From the above, when considering the maintainability of the injection molding machine 90, it is preferable to arrange the output port 861 of the decontamination machine 86 on the upper side in the vertical direction with respect to the injection molding machine 90 and the connecting device 70. Here, further considering ensuring maintenance space and avoiding interference with the motor, etc. 94, it is preferable to arrange the output port 861 of the decontamination machine 86 in a direction away from the motor, etc. 94 (on the first side in the connecting direction). In other words, the configuration shown in FIG. 10(A) is more preferable than the configuration shown in FIG. 10(B). This reduces the risk of the connecting device 70 interfering with the motor, etc. 94 due to extension and contraction of the connecting device 70.

[0135] 1, 2, 3, 4, 5, 6, 7... Molten resin supply system, 10, 20, 30, 40, 50, 60, 70... Connection device, 11, 12, 13, 14, 41, 42, 43, 44, 411, 412, 413, 414, 421, 611, 612, 613, 614, 622, 623, 631, 632, 633, 634... Pipe, 21, 22, 23, 51, 52, 53, 211, 2 12, 213, 311, 312, 313...Swivel joint, 31, 32, 61, 62, 511, 512, 521...Connecting member, 80, 81, 82, 83, 84, 85, 86...Decontamination machine, 90...Injection molding machine, 91...Heating cylinder, 92...Injection cylinder, 93...Mold, 94...Motor, etc., 801, 811, 821, 831, 841, 861...Output port, 911...Input port

Claims

1. A connecting device which connects an output device which outputs molten resin to be recycled from an output port, and an injection molding machine which has an input port for inputting the outputted molten resin, a heating cylinder which heats the molten resin, and an injection cylinder which is independent of the heating cylinder and injects the heated molten resin into a mold, one end of a pipe formed by a tube through which the molten resin passes and a swivel joint is connected to the output port, and the other end is connected to the input port, thereby connecting the output device and the injection molding machine.

2. The coupling device according to claim 1, characterized in that the number of said swivel joints provided in said coupling device is three.

3. The connecting device according to claim 1, wherein the swivel joint has a seal member having a predetermined heat resistance temperature and endurance pressure.

4. The connection device according to claim 1, characterized in that the connection device heats the piping to heat the molten resin passing through the piping.

5. The coupling device according to claim 4, characterized in that the coupling device heats the piping by a band heater.

6. A connecting device according to claim 1, characterized in that the swivel joint is rotatable by a sliding bearing, and a part of the molten resin is used as a lubricant for the sliding bearing.

7. A connecting device as claimed in claim 1, characterized in that the direction of the rotation axis of the swivel joint is not parallel to the vertical direction and is approximately perpendicular to the direction in which the heating cylinder moves.

8. The connecting device according to claim 1, characterized in that an imaginary line connecting one end and the other end of the pipe is approximately parallel to the direction in which the heating cylinder moves.

9. The connecting device according to claim 1, wherein an imaginary line connecting said one end and said other end of said pipe is substantially perpendicular to the rotation axis of said swivel joint.

10. A connecting device as described in claim 2, characterized in that the length of a first piping section including a swivel joint closest to said one end and the length of a third piping section including a swivel joint farthest from said one end are each 30% or less of the length of a second piping section including a swivel joint disposed between said first piping section and said third piping section.

11. A molten resin supply system comprising the output device, the injection molding machine, and the connecting device according to claim 1, wherein the output port of the output device is fixed in position, and the input port of the heating cylinder moves in position in accordance with the movement of the position of the heating cylinder.

12. A molten resin supply system comprising the output device, the injection molding machine, and the connecting device according to claim 1, characterized in that, even if the output device and the injection molding machine move relative to each other, a virtual line connecting the rotation axes of each of the three swivel joints connected via the two pipes does not form a single straight line when viewed from the top-bottom direction, or a process is performed to ensure that the virtual line does not form a single straight line when viewed from the top-bottom direction.

13. The molten resin supply system according to claim 11 or 12, characterized in that the output device or the injection molding machine performs control to reduce the internal pressure of the swivel joint depending on the magnitude of the internal pressure.

14. The molten resin supply system according to claim 13, wherein the output device or the injection molding machine performs control to reduce the pressure when outputting the molten resin from the output port.

15. The molten resin supply system according to claim 14, wherein the output device or the injection molding machine controls at least one of the output of the molten resin from the output device and the input of the molten resin to the injection molding machine as the control.

16. The molten resin supply system according to claim 13, wherein the output device calculates the magnitude of the internal pressure based on information detected at each of the inlet and outlet of the molten resin in the swivel joint.

17. A molten resin supply system as described in claim 11 or 12, characterized in that the output port of the output device and the input port of the injection molding machine are located in the vertical direction on the same or approximately the same horizontal line.

Images