Injection molding machine recycling system

Abstract

To provide a system for effectively recycling heat released to a surrounding atmosphere of an injection molding machine from a plasticization barrel.SOLUTION: A recycle system 1 of an injection molding machine 10 is assembled with a recycling circulation path 30 and a second heat exchanger 35 as an energy consumption structure. The recycling circulation path 30 is assembled with a first heat exchanger 31 for heating water W which is a heat medium receiving heat H generated in a heater 12 attached to a plasticization barrel 11, a storage tank 36 for storage of the water W, a forward passage piping 38 for discharging the water W stored in the storage tank 36 toward the first heat exchanger 31 and a return passage piping 33 for discharging the water W passed through the first heat exchanger 31 toward the storage tank 36. The second heat exchanger 35 is provided in the return passage piping 33 and consumes heat energy of the water W heated by the first heat exchanger 31.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a recycling system for reusing thermal energy released from the plasticizing barrel of an injection molding machine. [Background technology]

[0002] In an injection molding machine, pelletized thermoplastic resin is fed into a plasticization zone inside a plasticization barrel, also known as a heating cylinder. This resin is melted by a screw that is retractable into the plasticization zone and then injected into a mold cavity through a nozzle at the tip of the plasticization barrel. The molten resin is cooled and solidified in the mold cavity to obtain a molded product. The mold is then opened and the molded product is removed from the mold using an ejector pin or similar device, completing the production of the molded product.

[0003] The plasticizing barrel of an injection molding machine is provided with a heater, typically a heater that is heated by passing electricity, to melt the resin raw material. Patent Document 1 discloses an injection molding machine equipped with a power generation function that utilizes the temperature gradient that occurs between the plasticizing barrel and the temperature control unit of the resin supply port, and efficiently converts thermal energy into electrical energy using a thermoelectric conversion device. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-46169 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the power generation function of Patent Document 1 can only utilize the heat that flows from the plasticizing barrel into the resin supply port, and the heat that is radiated from the plasticizing barrel into the atmosphere surrounding the injection molding machine remains wasted. SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a system that can effectively recycle the heat that is radiated from the plasticizing barrel into the atmosphere surrounding the injection molding machine. [Means for solving the problem]

[0006] The recycling system for an injection molding machine according to the present invention comprises a recycling circulation path and an energy consuming structure. The recycle circulation path includes a first heat exchanger that receives heat from a heater attached to the plasticizing barrel and heats the heat medium, a storage tank that stores the heat medium, an outward piping that flows the heat medium stored in the storage tank toward the first heat exchanger, and a return piping that flows the heat medium that has passed through the first heat exchanger toward the storage tank. The energy consuming structure is provided in the return pipe and includes an energy consuming structure that consumes the thermal energy of the heat medium heated by the first heat exchanger.

[0007] The recycling system of the present invention may preferably include a second heat exchanger as an energy consuming structure through which a heat transfer medium passes, and a hydraulic oil heating circuit that heats hydraulic oil used in the injection molding machine using the second heat exchanger.

[0008] The recycling system of the present invention can preferably include a drive source as an energy consuming structure that converts thermal energy into mechanical energy when a heat medium passes through it, and a generator driven by the drive source. In this recycling system, the hydraulic oil is preferably supplied to the second heat exchanger by the hydraulic oil heating circuit when the temperature of the hydraulic oil is within a predetermined first temperature range.

[0009] The recycling system of the present invention may include a drive source as an energy consuming structure that converts thermal energy into mechanical energy as a heat transfer medium passes through it, a generator driven by the drive source, and may also include a second heat exchanger as an energy consuming structure that is located downstream of the generator and through which the heat transfer medium passes, and a hydraulic oil heating circuit that heats hydraulic oil used in the injection molding machine using the second heat exchanger.

[0010] This recycling system preferably includes a return pipe that causes the heat medium to flow to the second heat exchanger after passing through the driving source, and a bypass pipe that causes the heat medium to flow to the second heat exchanger without passing through the driving source. In this recycling system, the bypass pipe preferably branches off from the return pipe upstream of the driving source and merges with the return pipe downstream of the driving source and upstream of the second heat exchanger. In this recycling system, if the heated state of the heat medium is relatively low, the heat medium flows through the bypass piping to the second heat exchanger, and if the heated state of the heat medium is relatively high, the heat medium flows through the return piping to the driving source and the second heat exchanger in that order. [Effects of the Invention]

[0011] The present invention provides a system that can effectively recycle heat that is dissipated from the plasticizing barrel into the atmosphere surrounding the injection molding machine. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a diagram showing a schematic configuration of a recycling system according to a first embodiment. [Figure 2] FIG. 3 is a flow chart showing the operation of the recycling system according to the first embodiment. [Figure 3] FIG. 10 is a diagram showing the configuration of a recycling system according to a second embodiment. [Figure 4] FIG. 10 is a diagram showing the configuration of a recycling system according to a third embodiment. [Figure 5] FIG. 10 is a flowchart showing the operation of the recycling system according to the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. Below, three embodiments, namely, a first embodiment, a second embodiment and a third embodiment, will be described in order. The first embodiment recycles energy by using thermal energy radiated from the plasticizing barrel to heat hydraulic oil, which is used to smoothly operate the injection molding machine. In the second embodiment, the thermal energy released from the plasticizing barrel is used to generate electricity, thereby recycling energy. In the third embodiment, the thermal energy generated by the heat radiation from the plasticizing barrel is used to heat the hydraulic oil and generate electricity, thereby recycling energy.

[0014] [First embodiment: Figs. 1 and 2] The recycling system 1 according to the first embodiment includes an injection molding machine 10 and a recycle circulation path 30 that recycles thermal energy generated by heat dissipation from the plasticizing barrel 11 in the injection molding machine 10 by heating hydraulic oil. Below, the configurations of the injection molding machine 10 and the recycle circulation path 30 will be described in that order with reference to Fig. 1, and then the operating procedure of the recycling system 1 will be described with reference to Fig. 2. The injection molding machine 10 described below focuses on heat dissipation from the plasticizing barrel 11, so the mold is omitted and the illustration focuses on the plasticizing portion.

[0015] [Configuration of injection molding machine 10: Figure 1] The injection molding machine 10 includes a cylindrical plasticizing barrel 11, a heater 12 provided around the plasticizing barrel 11, a screw 13 provided inside the plasticizing barrel 11, and a discharge nozzle 15 provided at the front (F) downstream end (front (F)). The injection molding machine 10 also includes a resin supply hopper 17 on the rear (B) side that holds resin pellets P, and the resin pellets P are supplied into the plasticizing barrel 11 through a supply hole 19 that penetrates the inside and outside of the plasticizing barrel 11.

[0016] The injection molding machine 10 includes a first electric motor 21 that moves the screw 13 forward or backward, and a second electric motor 23 that rotates the screw 13 forward or backward about a rotation axis. Each of the elements described above performs the necessary operation in accordance with instructions from the control unit 100. The actuator for advancing or retracting the screw 13 may be a hydraulically driven actuator instead of an electric motor.

[0017] The operation of the injection molding machine 10 is generally as follows. When the screw 13 provided inside the plasticizing barrel 11 rotates, resin pellets P made of thermoplastic resin supplied from a resin supply hopper 17 are sent out toward the discharge nozzle 15 at the downstream end of the plasticizing barrel 11. The resin pellets P are melted as the screw 13 rotates, and as the resin pellets P melt, the screw 13 moves backward while receiving back pressure, and then moves forward to perform injection. During this series of injection operations, the heater 12 is heated to heat the resin pellets P inside the plasticizing barrel 11, thereby contributing to the melting of the resin pellets P.

[0018] [Configuration of the recycling circulation route 30: Figure 1] Next, the configuration of the recycle circulation path 30 will be described with reference to FIG. The recycle circulation path 30 includes a first heat exchanger 31 disposed opposite the heater 12 of the injection molding machine 10, an outward piping 38 connected to one end of the first heat exchanger 31, and a return piping 33 connected to the other end of the first heat exchanger 31. The first heat exchanger 31 may be a simple piping member, but preferably has a structure similar to a so-called radiator, with numerous fins separated by narrow gaps on the outer wall surface of the piping. Alternatively, the first heat exchanger 31 may be configured, for example, as a piping with numerous fins on the inner wall surface. In this case, the fins may have a structure (e.g., an uneven shape) that increases the surface area of ​​the piping through which the heat medium flows. The fins are not limited to flat plates protruding from the wall surface (a typical fin shape), but may also be corrugated plates connected to the inner or outer wall of the piping so as to allow heat transfer. The first heat exchanger 31, the outbound piping 38, and the return piping 33 form a circulation path for the fluid (steam, water). The outbound piping 38 and the return piping 33 are designated upstream (U) and downstream (D) based on the direction of fluid flow. The end of the outbound piping 38 connected to the first heat exchanger 31 is designated downstream (D), while the end immersed in the storage tank 36 is designated upstream (U). The end of the return piping 33 connected to the first heat exchanger 31 is designated upstream (U), while the end immersed in the storage tank 36 is designated downstream (D). Water W flows from upstream (U) to downstream (D) in the outbound piping 38, while steam S flows from upstream (U) to downstream (D) in the return piping 33. Although not shown, a first heat exchanger thermometer is provided to measure the temperature of the first heat exchanger 31. The temperature of the first heat exchanger measured by this first heat exchanger thermometer is continuously provided to the control unit 100.

[0019] The upstream (U) end of the outbound piping 38 is immersed in the water W stored in the storage tank 36, and the downstream (D) end is connected to the first heat exchanger 31. A first pump 39 is provided in the outbound piping 38, and pumps the water W stored in the storage tank 36 up into the outbound piping 38 and supplies it toward the first heat exchanger 31.

[0020] A second heat exchanger 35 and a condenser 37 are provided in this order from the upstream (U) side on the return pipe 33. A hydraulic oil heating circuit 40 is provided in the second heat exchanger 35, and the hydraulic oil HO required for the operation of the injection molding machine 10 is heated by heat exchange between the steam S flowing through this second heat exchanger 35 and the hydraulic oil HO. Here, an example is shown in which steam S is generated as a result of water W being heated by the first heat exchanger 31, but it is also possible to use water W in a high-temperature state that can heat the hydraulic oil HO through heat exchange.

[0021] The second heat exchanger 35 includes a heating-side flow path piping 35A connected to the return line 33 and a housing cylinder 35B that hermetically houses the heating-side flow path piping 35A. The heated-side flow path 35C is defined within the housing cylinder 35B, surrounding the heating-side flow path piping 35A. Steam S, which flows from the upstream (U) through the return line 33, flows into the heating-side flow path piping 35A and heats the hydraulic oil HO flowing through the heated-side flow path 35C as it passes through the heating-side flow path piping 35A. Hydraulic oil HO flows into the heated-side flow path 35C from the hydraulic oil heating circuit 40 and is heated by receiving heat from the steam S as it passes through the heated-side flow path 35C. Elements of the second heat exchanger 35, such as the heating-side flow path piping 35A and the housing cylinder 35B, are made of a metal material with high thermal conductivity, such as a copper alloy. The second heat exchanger 35 may be of any known type as long as its intended purpose is achieved.

[0022] The condenser 37 cools and condenses the water vapor (low-pressure wet steam) after heat exchange in the second heat exchanger 35, and returns it to low-pressure saturated liquid water W. The water W produced in the condenser 37 passes through the downstream (D) side of the outbound piping 38 and is returned to the storage tank 36.

[0023] The hydraulic oil heating circuit 40 includes an outward piping 41 that supplies hydraulic oil HO stored in the hydraulic oil tank 45 to the heated side flow path 35C of the second heat exchanger 35, and a second pump 43 that supplies the hydraulic oil HO stored in the hydraulic oil tank 45 to the heated side flow path 35C via the outward piping 41. The outgoing pipe 41 has an upstream end immersed in the hydraulic oil HO stored in the hydraulic oil tank 45, and a downstream end connected to the downstream side of the housing cylinder 35B of the second heat exchanger 35. By driving the second pump 43 provided in the outgoing pipe 41, the hydraulic oil HO stored in the hydraulic oil tank 45 is pumped up into the outgoing pipe 41 and supplied to the heated-side flow path 35C. Although not shown, a hydraulic oil thermometer is provided to measure the temperature of the hydraulic oil HO stored in the hydraulic oil tank 45. The temperature of the hydraulic oil measured by this hydraulic oil thermometer is continuously provided to the control unit 100.

[0024] The hydraulic oil heating circuit 40 includes a return pipe 47 that returns the heated hydraulic oil HO through the heated-side flow path 35C to the hydraulic oil tank 45, and a gate valve 49 provided in the return pipe 47. The return pipe 47 has an upstream end connected to the housing cylinder 35B and connected to the heated-side flow path 35C, and a downstream end immersed in the hydraulic oil HO stored in the hydraulic oil tank 45. The hydraulic oil HO passing through the heated-side flow path 35C by the driving force of the second pump 43 flows into the return pipe 47 in a heated state and is returned to the hydraulic oil tank 45. Although not shown, hydraulic oil pipes are provided to supply the hydraulic oil HO from the hydraulic oil tank 45 to each part of the injection molding machine 10.

[0025] [Operation of Recycling System 1: Figure 2] Next, the operation of the recycling system 1 while the injection molding machine 10 is repeatedly performing injection molding will be described with reference to Figure 2. It is assumed that the heating function of the heater 12 is stopped, the first pump 39 of the recycling circulation path 30 and the second pump 43 of the hydraulic oil heating circuit 40 are stopped, and the gate valve 49 is closed.

[0026] As injection molding begins using the injection molding machine 10, the resin pellets P are heated by the heater 12 via the plasticizing barrel 11. The heat from the heater 12 is not entirely used to heat the resin pellets P; it also heats the area around the plasticizing barrel 11. Therefore, a considerable amount of heat H exists in the plasticizing barrel 11 and its surroundings that is not used to heat the resin pellets P. As shown in FIG. 1, this heat H is transferred to a first heat exchanger 31 that is provided around the plasticizing barrel 11 in association with the heater 12. While FIG. 1 shows an example in which the first heat exchanger 31 absorbs heat radiated from the heater 12 to the surroundings, the heat H may also be transferred to the first heat exchanger 31 via a fixing member (not shown) that fixes the first heat exchanger 31 to the plasticizing barrel 11.

[0027] Water W flows through the first heat exchanger 31, and the water W receives heat H through the first heat exchanger 31, changes phase to steam S, and flows downstream (D) through the outbound piping 38 to reach the second heat exchanger 35. The second heat exchanger 35 forms part of a hydraulic oil circulation path consisting of the outbound piping 41, the return piping 47, and the hydraulic oil tank 45. Therefore, the hydraulic oil HO flowing through the heated-side flow path 35C of the second heat exchanger 35 receives heat from the heating-side flow path piping 35A heated by the steam S while flowing through the hydraulic oil circulation path.

[0028] The steam S that has passed through the second heat exchanger 35 reaches the condenser 37, where it becomes liquid water W and then returns to the storage tank 36. The water W in the storage tank 36 flows through the outbound piping 38 toward the first heat exchanger 31 by the driven first pump 39.

[0029] An example of a specific operation procedure of the recycle system 1 will be described with reference to FIG. When the injection molding machine 10 starts injection molding, a switch (SW) is turned on to start the operation of the hydraulic oil temperature raising circuit 40 (FIG. 2, S101). This switch is not shown, but may be provided in the control unit 100, for example, and may be turned on automatically when injection molding starts, or may be turned on by an operator who operates the injection molding machine 10. Next, the heater 12 and the first pump 39 are turned on, i.e., operation begins (FIG. 2, S103). The control unit 100 continuously acquires information about the temperature of the first heat exchanger 31 (first heat exchanger temperature Tr) from a temperature sensor provided in the first heat exchanger 31 and compares it with a first reference temperature T1 stored in the control unit 100 (FIG. 2, S105). Note that the first heat exchanger temperature Tr may be the temperature of the housing of the first heat exchanger 31, or the temperature of the water W or steam S flowing inside the first heat exchanger 31. The first reference temperature T1 is a condition for opening (ON) the gate valve 49 and starting (ON) operation of the second pump 43. The control unit 100 waits until the first heat exchanger temperature Tr is equal to or greater than the first reference temperature T1 before issuing an instruction to turn on the gate valve 49 and the second pump 43 (FIG. 2, S105, Yes, S107).

[0030] After the gate valve 49 and the second pump 43 are turned on, the control unit 100 continuously acquires information about the temperature of the hydraulic oil HO (hydraulic oil temperature Toil) and compares it with the third reference temperature T3 stored in the control unit 100. The third reference temperature T3 serves as an upper limit for the temperature of the hydraulic oil HO, which is set to prevent the hydraulic oil HO from heating up more than necessary. Therefore, if the control unit 100 determines that the hydraulic oil temperature Toil is greater than or equal to the third reference temperature T3 (Yes in S109 of FIG. 2), it closes the gate valve 49 (OFF) and instructs the first pump 39 and the second pump 43 to stop (OFF) in order to prevent the hydraulic oil HO from heating up too much (S111 of FIG. 2). At this time, the first pump 39 may remain ON, while only the second pump 43 may be turned OFF. On the other hand, if the hydraulic oil temperature Toil is lower than the third reference temperature T3 (FIG. 2, S109, No), the control unit 100 keeps the gate valve 49 ON, the first pump 39, and the second pump 43 ON (FIG. 2, S107).

[0031] After turning off the gate valve 49, the first pump 39, and the second pump 43, the control unit 100 determines whether or not there is an instruction to stop (turn off) the hydraulic oil temperature increasing circuit 40 (S113 in FIG. 2). The control unit 100 compares the continuously acquired hydraulic oil temperature Toil with the fourth reference temperature T4 stored therein (FIG. 2, S115) until it receives a command to turn off the hydraulic oil heating circuit 40 (FIG. 2, S113, No). The fourth reference temperature T4 is set to determine whether the hydraulic oil HO temperature needs to be increased, and serves as a lower limit for the temperature of the hydraulic oil HO. If the hydraulic oil temperature Toil is equal to or greater than the fourth reference temperature T4 (FIG. 2, S115, Yes), the control unit 100 continues to turn off the gate valve 49 and the first and second pumps 39 and 43 (FIG. 2, S111). At this time, if the first pump 39 was left ON in FIG. 2, S111 immediately after FIG. 2, S109, it is also possible to turn off only the second pump 43 while leaving the first pump 39 ON. On the other hand, if the hydraulic oil temperature Toil is lower than the fourth reference temperature T4 (No in S115 in FIG. 2), the control unit 100 determines that it is necessary to increase the temperature of the hydraulic oil HO, and performs the process of turning on the heater 12 and the first pump 39 (S103 in FIG. 2) and subsequent processes in the above-described procedure. Note that with respect to the hydraulic oil temperature Toil, the temperature range between the third reference temperature T3 and the fourth reference temperature T4 corresponds to the first temperature range of the present invention.

[0032] As described above, while the injection molding machine 10 is performing injection molding, the recycling system 1 can heat and maintain the hydraulic oil HO stored in the hydraulic oil tank 45 at an appropriate temperature that allows the hydraulic oil HO to function normally as the hydraulic oil HO for the injection molding machine 10, without providing a separate heating device such as an electric heater dedicated to heating the hydraulic oil HO. As a result, the injection molding machine 10, which uses the hydraulic oil HO stored in the hydraulic oil tank 45, and the recycling circulation path 30, which includes the hydraulic oil heating circuit 40, can continue to operate smoothly because they use the hydraulic oil HO heated to an appropriate temperature.

[0033] [Second embodiment: Figure 3] Next, a recycle system 3 according to a second embodiment will be described with reference to Fig. 3. Note that parts of the recycle system 3 that are common to the recycle system 1 will be given the same reference numerals as those of the recycle system 1 (Fig. 1), and descriptions thereof may be omitted.

[0034] The recycle system 3 includes an electric power recovery circuit 50 as an alternative to the recycle circulation path 30 that heats the hydraulic oil HO of the recycle system 1. The electric power recovery circuit 50 includes a driving source 51 and a generator 53 that generates electric power when driven by the driving source 51. The drive source 51 is provided in the return pipe 33, and converts thermal energy into mechanical energy as steam S, which serves as a heat medium and flows through the return pipe 33, passes through it. The drive source 51 may take any form, and a wide range of mechanical elements that are driven by receiving steam S are applicable. For example, a rotary vane mechanism such as a turbine that rotates when receiving steam S, or a reciprocating piston mechanism that reciprocates when receiving steam S, are applicable. When a reciprocating piston mechanism is applied, its linear motion can be converted into rotary motion to rotate the generator 53.

[0035] The generator 53 converts mechanical energy generated by the drive source 51 into electrical energy. The generator 53 is broadly classified into a DC generator and an AC generator depending on the type of power it generates, but any of these generators is applicable in this embodiment. AC generators are further divided into synchronous generators, induction generators, and high-frequency generators, and any of these generators is applicable.

[0036] [Recycling System 3 Operation] The operation of the recycle system 3 will be described below, focusing on the differences from the recycle system 1.

[0037] In the first heat exchanger 31, the water W becomes steam S, which flows downstream (D) through the return pipe 33 and reaches the driving source 51. As an example, the driving source 51 is rotationally driven by receiving the steam S, and this rotational driving force rotates the generator 53 via the output shaft 52 of the driving source 51. This causes the generator 53 to generate electric power. This electric power is supplied to an electric power consumer through an electric wire (not shown). As the electric power consumer, the electric power is supplied to the injection molding machine 10 and its surrounding electric devices, or it can be regenerated as a power source for the injection molding machine 10. Furthermore, the electric power generated by the generator 53 can be supplied to drive the first pump 39 or the second pump 43, or can be stored in an electric power storage system such as a storage battery or a flywheel.

[0038] The steam S that has passed through the second heat exchanger 35 reaches the condenser 37, where it becomes liquid water W and then returns to the storage tank 36. The water W in the storage tank 36 flows through the return pipe 33 toward the first heat exchanger 31 by the driven first pump 39.

[0039] In this way, the recycling system 2 can generate power using the power recovery circuit 50 while the injection molding machine 10 is performing injection molding. This allows the power recovery circuit 50 to supply power to the injection molding machine 10 and its surrounding electrical devices. If the energy of the steam S generated by the first heat exchanger 31 is insufficient to drive the generator 53, an auxiliary heating device such as a heat pump (not shown) can be provided in the outbound piping 38, and this auxiliary heating device can replenish energy to increase the energy of the steam S to a level sufficient to drive the generator 53. Although the use of the auxiliary heating device requires new energy, it is possible to recover a greater amount of energy from the heated steam S than that added by the auxiliary heating device. The electricity generated by the generator 53 may be regenerated as a power source or stored in a storage battery. The operation flow of the recycling system 3 according to the second embodiment is based on the operation flow of the recycling system 1 according to the first embodiment described with reference to Fig. 2. In other words, when the "operation heating circuit" in the operation flow of Fig. 2 is replaced with the "power recovery circuit", the operation flow becomes the operation flow of the recycling system 3.

[0040] [Third embodiment: Figures 4 and 5] Next, a recycling system 5 according to a third embodiment will be described with reference to Figures 4 and 5. Note that parts of the recycling system 5 that are common to the recycling systems 1 and 3 will be given the same reference numerals as those of the recycling systems 1 and 3 (Figures 1 and 3), and descriptions thereof may be omitted.

[0041] 4, the recycling system 5 includes a hydraulic oil heating circuit 40 that heats the hydraulic oil HO of the recycling system 1, as well as an electric power recovery circuit 50 of the recycling system 3. However, the hydraulic oil heating circuit 40 is provided downstream (D) of the electric power recovery circuit 50 in the flow direction of the steam S. Furthermore, a three-way valve 32 is provided in the return pipe 33 upstream of the electric power recovery circuit 50, and a bypass pipe 34 that bypasses the electric power recovery circuit 50 and heads toward the second heat exchanger 35 is connected to the three-way valve 32. The three-way valve 32 includes a first route 32A that supplies steam S to the second heat exchanger 35 via a bypass pipe 34, and a second route 32B that supplies steam S toward a driving source 51 of the power recovery circuit 50 via an outward pipe 38. When the first route 32A is selected (open) and the second route 32B is not selected (closed), the steam S is supplied toward the second heat exchanger 35 through the bypass pipe 34, but is not supplied to the driving source 51. When the second route 32B is selected (open) and the first route 32A is not selected (closed), the steam S is supplied to the driving source 51 and the second heat exchanger 35 in that order. The hydraulic oil temperature increasing circuit 40 and the power recovery circuit 50 are the same as those in the first and second embodiments, respectively.

[0042] [Recycling System 5 Operation] The operation of the recycling system 5 will now be described. In the first heat exchanger 31, the water W becomes steam S, which flows downstream (D) through the return pipe 33 and reaches the driving source 51. As an example, the driving source 51 is rotationally driven by receiving the steam S, and this rotational driving force rotates the generator 53 via the output shaft 52 of the driving source 51. This causes the generator 53 to generate electric power. This electric power is supplied to an electric power consumer through electric wires (not shown).

[0043] The steam S that has passed through the second heat exchanger 35 reaches the second heat exchanger 35, and heats the hydraulic oil HO flowing through the heated-side flow path 35C in the same manner as in the first embodiment.

[0044] The steam S that has passed through the second heat exchanger 35 reaches the condenser 37, where it becomes liquid water W and then returns to the storage tank 36. The water W in the storage tank 36 flows through the outbound piping 38 toward the first heat exchanger 31 by the driven first pump 39.

[0045] As described above, while the injection molding machine 10 is performing injection molding, the recycling system 5 can generate power using the power recovery circuit 50 and heat the hydraulic oil HO stored in the hydraulic oil tank 45 to an appropriate temperature. This allows the power recovery circuit 50 to provide part of the power required for the recycling circulation path 30 including the injection molding machine 10 and the hydraulic oil heating circuit 40, and also heats the hydraulic oil HO stored in the hydraulic oil tank 45 to an appropriate temperature.

[0046] An example of a specific operation procedure of the recycling system 5 will be described with reference to FIG. When the injection molding machine 10 starts injection molding, a switch (SW) is turned on to start the operation of the power recovery circuit 50 (FIG. 5, S201). This switch is not shown, but may be provided in the control unit 100, for example, and may be turned on automatically when injection molding starts, or may be turned on by an operator who operates the injection molding machine 10. Next, the heater 12 and the first pump 39 are turned on, i.e., operation begins (FIG. 2, S203). The control unit 100 continuously acquires information about the temperature of the first heat exchanger 31 (first heat exchanger temperature Tr) from a temperature sensor provided in the first heat exchanger 31 and compares it with a first reference temperature T1 stored in the control unit 100. The first reference temperature T1 is a condition for opening (ON) the gate valve 49 and starting (ON) operation of the second pump 43. After waiting for the first heat exchanger temperature Tr to be equal to or greater than the first reference temperature T1, the control unit 100 issues an instruction to turn on the gate valve 49 and the second pump 43, as well as to open the first route 32A of the three-way valve 32 and close the second route 32B (FIG. 5, S205, Yes, S207). The steam S flowing through the return pipe 33 then flows into the branch pipe 34 via the three-way valve 32 and reaches the hydraulic oil heating circuit 40.

[0047] After turning on the gate valve 49, the second pump 43, and the first route 32A of the three-way valve 32, the control unit 100 compares the continuously acquired first heat exchanger temperature Tr with the second reference temperature T2 stored therein (FIG. 5, S209). The second reference temperature T2 serves as a lower limit of the temperature at which steam S begins to flow into the power recovery circuit 50, and is set to prevent the temperature of the hydraulic oil HO from being increased more than necessary by the steam S. If the control unit 100 confirms that the first heat exchanger temperature Tr is equal to or greater than the second reference temperature T2 (FIG. 5, S209, Yes), it instructs the three-way valve 32 to open the second route 32B and close the first route 32A (FIG. 5, S211). On the other hand, if the first heat exchanger temperature Tr is less than the second reference temperature T2 (FIG. 5, S209, No), the control unit 100 keeps the gate valve 49 ON, the first pump 39, and the second pump 43 ON, and keeps the first route 32A of the three-way valve 32 open (FIG. 5, S207). The control unit 100 then determines whether or not an instruction to stop (turn off) the switch SW of the power recovery circuit 50 has been issued (FIG. 5, S213).

[0048] The control unit 100 compares the continuously acquired first heat exchanger temperature Tr with the fifth reference temperature T5 stored therein (FIG. 5, S215) until it receives an instruction to turn off the power recovery circuit 50 (FIG. 5, S213, No). The fifth reference temperature T5 serves as a reference temperature for determining whether steam S needs to flow into the power recovery circuit 50 or whether the drive source 51 in the power recovery circuit 50 can be driven to generate electricity with the generator 53. If the first heat exchanger temperature Tr is equal to or greater than the fifth reference temperature T5 (FIG. 5, S215, Yes), the control unit 100 opens the second route 32B and keeps the first route 32A closed so that steam S continues to flow into the power recovery circuit 50 (FIG. 5, S211). On the other hand, if the first heat exchanger temperature Tr is less than the fifth reference temperature T5 (FIG. 5, S215, No), the control unit 100 determines that it is not necessary to introduce steam S into the power recovery circuit 50, and instructs the three-way valve 32 to open the first route 32A and close the second route 32B (FIG. 5, S207), and performs the subsequent processing in the above-described procedure. Note that with respect to the first heat exchanger temperature Tr, the temperature range between the second reference temperature T2 and the fifth reference temperature T5 corresponds to the second temperature range of the present invention.

[0049] If there is an instruction to turn off the power recovery circuit 50 (FIG. 5, S213 Yes), the control unit 100 issues an instruction to turn off the gate valve 49, the first pump 39, and the second pump 43, and ends the series of controls.

[0050] As described above, the recycling system 5 according to the third embodiment includes the return pipe 33, which flows the water W, which is a heat medium, to the second heat exchanger 35 after passing through the driving source 51, and the bypass pipe 34, which flows the water W to the second heat exchanger 35 without passing through the driving source 51. The bypass pipe 34 branches off from the return pipe 33 upstream of the driving source 51 and merges with the return pipe 33 downstream of the driving source 51 and upstream of the second heat exchanger 35. If the heated state of the water W is relatively low, the water W flows through the bypass pipe 34 to the second heat exchanger 35, and if the heated state of the water W is relatively high, the water W flows through the return pipe 33 to the driving source 51 and the second heat exchanger 35 in that order.

[0051] [Effects of the first to third embodiments] The first to third embodiments provide the following effects. The heat H from the heater 12, which was previously wasted by dissipating heat into the atmosphere, can now be used to quickly raise the temperature of the hydraulic oil or maintain it at a specified high temperature, eliminating the need for a dedicated electric heater and contributing to energy conservation and carbon neutrality. This is particularly effective in cold temperatures such as winter, when the temperature of the hydraulic oil may not be raised sufficiently.

[0052] Furthermore, the heat H from the heater 12, which would otherwise be wasted by dissipating it into the atmosphere, can be recycled as electricity and reused to heat the hydraulic oil, contributing to energy savings and carbon neutrality. In particular, in an ultra-large injection molding machine 10 in which the diameter of the screw 13 exceeds φ100 mm, it is possible to generate steam sufficient to drive a generator.

[0053] It is possible that the heat H from the steam S generated in the first heat exchanger 31 opposite the heater 12 is too high to raise the temperature of the hydraulic oil HO. In this case, the energy of the steam S is reduced by driving the generator 53 with the steam generated in the first heat exchanger 31. This allows the temperature of the steam S or high-temperature hot water HW input into the second heat exchanger 35 for the hydraulic oil HO to be reduced to a temperature suitable for raising the temperature of the hydraulic oil HO, thereby preventing the hydraulic oil HO from being heated excessively.

[0054] In addition to the above, the configurations given in the above embodiments can be selected or changed as appropriate to other configurations without departing from the spirit of the present invention. For example, while the second heat exchanger 35 for raising the temperature of the hydraulic oil HO and the drive source 51 for driving the generator 53 have been exemplified as the energy consumption structure, the present invention is not limited to this. Devices that can use steam S in the factory where the injection molding machine 10 operates, such as a mold heating device, a raw resin preheating device, or a heater for heating the area around the injection molding machine 10, may also be included in the recycle circulation path. In the above embodiment, water W is used as an example of the heat transfer medium, but the present invention is not limited to this. The present invention allows the use of an inert gas such as nitrogen gas, a gas such as air, or a high-flash-point oil whose ignition temperature is higher than the molding temperature as the heat transfer medium. In addition, a pressure relief valve may be provided in the outbound piping 38 as a safety valve to prevent the heat medium pressure in the piping from becoming excessive. In this case, the heat medium released by the pressure relief valve may be released to the atmosphere or sent to the condenser 37.

[0055] Furthermore, a heat insulating material may be provided directly or indirectly around the periphery of the first heat exchanger 31. This prevents the heat radiated from the heater 12 to the surroundings from leaking without being absorbed by the first heat exchanger 31, and allows the heat to be effectively absorbed by the first heat exchanger 31, thereby increasing the efficiency of recycling the heat radiated from the plasticizing barrel 11 to the atmosphere surrounding the injection molding machine 10. Furthermore, the temperature of the steam S may be measured and the flow rate of the water W supplied to the first heat exchanger 31 may be limited so that the temperature does not fall below a predetermined temperature. As a method for limiting the flow rate of the water W, a flow control valve may be provided in the recycle circulation path, for example, midway along the outbound piping 38 or between the storage tank 36 and the first pump 39 to limit the flow rate of the water W, or a servo motor may be used as the motor that drives the first pump 39 and the flow rate of the water W may be limited by controlling the rotation speed of the servo motor. This makes it possible to maintain the temperature of the steam S generated in the first heat exchanger 31 at a predetermined value or higher, thereby contributing to maintaining the energy of the steam S at a level sufficient to heat the hydraulic oil HO at a predetermined temperature or higher, or sufficient to drive the generator 53.

[0056] Furthermore, in the second embodiment, as in the third embodiment, the three-way valve 32 may be provided upstream of the power recovery circuit 50 on the return piping 33, and a bypass piping that bypasses the power recovery circuit 50 and leads to the condenser 37 may be connected to the three-way valve 32. As a result, when the temperature of the steam S is below a predetermined temperature at which the driving source 51 in the power recovery circuit 50 can be driven to generate electricity in the generator 53 or at which the power generation efficiency is high, the first route 32A of the three-way valve 32 is opened, and the second route 32B is opened after the temperature of the steam S reaches or exceeds a predetermined temperature at which the driving source 51 in the power recovery circuit 50 can be driven to generate electricity in the generator 53 or at which the power generation efficiency is high. This makes it possible to generate electricity at a temperature of the steam S at which the generator 53 can be operated in an appropriate or highly efficient and stable state. [Explanation of symbols]

[0057] 1,3,5 Recycling System 10 injection molding machine 11 Plasticizing Barrel 12 Heater 13 Screw 15 Discharge nozzle 17 Resin supply hopper 19 Supply hole 21 1st electric motor 23 Second electric motor 30 Recycling Circulation Route 31 1st heat exchanger 33 Return piping 34 Bypass piping 35 Second heat exchanger 35A heating side flow path piping 35B storage tube 35C Heated side flow path 36 Reservoir 37 Condenser 38 Outward piping 39 First Pump 40 Hydraulic oil temperature rise circuit 41 Outgoing piping 43 Second Pump 45 Hydraulic oil tank 47 Return piping 49 Gate valve 50 Power recovery circuit 51 Power Source 53 Generator 100 control section H fever P resin pellets S Steam W water HO hydraulic oil

Claims

1. a first heat exchanger that receives heat from a heater associated with the plasticizing barrel and heats a heat medium; a storage tank for storing the heat medium; an outgoing pipe for causing the heat medium stored in the storage tank to flow toward the first heat exchanger; a recycle circulation path including a return pipe for causing the heat medium that has passed through the first heat exchanger to flow toward the storage tank; a second heat exchanger provided in the return pipe as an energy consuming structure that consumes thermal energy of the heat medium heated by the first heat exchanger; a hydraulic oil heating circuit that supplies hydraulic oil used in the injection molding machine to the second heat exchanger.

2. When the temperature of the hydraulic oil is within a predetermined first temperature range, The hydraulic oil is supplied to the second heat exchanger by the hydraulic oil heating circuit. The recycling system according to claim 1 .

3. A first heat exchanger that receives heat from a heater attached to the plasticizing barrel and heats a heat medium; a storage tank for storing the heat medium; an outgoing pipe for causing the heat medium stored in the storage tank to flow toward the first heat exchanger; a recycle circulation path including a return pipe for causing the heat medium that has passed through the first heat exchanger to flow toward the storage tank; a drive source as an energy consuming structure that is provided in the return pipe and converts the thermal energy into mechanical energy when the heat medium heated by the first heat exchanger passes through the drive source; a generator driven by the drive source.

4. A first heat exchanger that receives heat from a heater attached to the plasticizing barrel and heats a heat medium; a storage tank for storing the heat medium; an outgoing pipe for causing the heat medium stored in the storage tank to flow toward the first heat exchanger; a recycle circulation path including a return pipe for causing the heat medium that has passed through the first heat exchanger to flow toward the storage tank; a drive source as an energy consuming structure that is provided in the return pipe and converts the thermal energy into mechanical energy when the heat medium heated by the first heat exchanger passes through the drive source; a generator driven by the drive source; a second heat exchanger as the energy consuming structure, the second heat exchanger being provided downstream of the generator and through which the heat medium passes; a hydraulic oil heating circuit that heats the hydraulic oil used in the injection molding machine by the second heat exchanger.

5. the return pipe that causes the heat medium to flow into the second heat exchanger after passing through the driving source; a bypass pipe that causes the heat medium to flow to the second heat exchanger without passing through the driving source, the bypass pipe branches off from the return pipe upstream of the driving source and merges with the return pipe downstream of the driving source and upstream of the second heat exchanger; If the heating state of the heat medium is relatively low, the heat medium flows through the bypass pipe to the second heat exchanger, If the heated state of the heat medium is relatively high, the heat medium passes through the return pipe and flows sequentially to the driving source and the second heat exchanger. The recycling system according to claim 4.

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