Die-casting machine, and power regeneration method in a die-casting machine

Abstract

The energy contained in the hydraulic fluid discharged into the tank is utilized effectively. [Solution] A die-casting machine comprising a hydraulic source, an injection cylinder for injecting molten metal using hydraulic fluid supplied from the hydraulic source, a tank for storing the hydraulic fluid, a hydraulic source return pipe connecting the hydraulic source and the tank and returning the hydraulic fluid discharged from the hydraulic source to the tank, and an injection cylinder return pipe connecting the injection cylinder and the tank and returning the hydraulic fluid discharged from the injection cylinder to the tank, wherein a regenerative power generation means for regenerating the fluid energy of the hydraulic fluid to generate electricity is provided in either the hydraulic source return pipe or the injection cylinder return pipe, or both.

Description

Technical Field

[0001] The present disclosure relates to a die casting machine and an electric power regeneration method in a die casting machine.

Background Art

[0002] Patent Document 1 discloses a die casting machine including: a sleeve that communicates with a cavity formed in a mold; a plunger that supplies molten metal in the sleeve to the cavity; and a hydraulic cylinder that advances the plunger when hydraulic oil is supplied to a head chamber and retracts the plunger when hydraulic oil is supplied to a rod chamber. This die casting machine is provided with a hydraulic circuit that supplies and discharges hydraulic oil to and from the head chamber and the rod chamber, and the hydraulic circuit has a hydraulic oil tank that stores the hydraulic oil.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of Invention

Problems to be Solved by the Invention

[0004] The present disclosure provides a die casting machine capable of effectively utilizing energy possessed by hydraulic oil discharged to a tank, and an electric power regeneration method in a die casting machine.

Means for Solving the Problems

[0005] [1] A die-casting machine comprising a hydraulic source, an injection cylinder for injecting molten metal using hydraulic fluid supplied from the hydraulic source, a tank for storing the hydraulic fluid, a hydraulic source return pipe connecting the hydraulic source and the tank and returning the hydraulic fluid discharged from the hydraulic source to the tank, and an injection cylinder return pipe connecting the injection cylinder and the tank and returning the hydraulic fluid discharged from the injection cylinder to the tank, wherein a regenerative power generation means for regenerating the fluid energy of the hydraulic fluid to generate electricity is provided in either the hydraulic source return pipe or the injection cylinder return pipe, or both.

[0006] [2] A die-casting machine as described in [1] above, wherein the hydraulic power source return pipe and the injection cylinder return pipe merge at a junction before the tank, and when the regenerative power generation means is provided in both the hydraulic power source return pipe and the injection cylinder return pipe, the regenerative power generation means is provided between the junction and the tank.

[0007] [3] A die-casting machine as described in [1] above, wherein the hydraulic source return pipe and the injection cylinder return pipe merge at a confluence before the tank, and the regenerative power generation means is provided in both the hydraulic source return pipe and the injection cylinder return pipe, the regenerative power generation means is provided in each of the hydraulic source return pipe and the injection cylinder return pipe in a section upstream of the confluence.

[0008] [4] A power regeneration method performed in a die-casting machine comprising a hydraulic power source, an injection cylinder for injecting molten metal using hydraulic fluid supplied from the hydraulic power source, and a tank for storing the hydraulic fluid, comprising: a first discharge step of returning the hydraulic fluid discharged from the hydraulic power source to the tank; a second discharge step of returning the hydraulic fluid discharged from the injection cylinder to the tank; and a power generation step of generating electricity, wherein the power generation step generates electricity by regenerating the fluid energy of the hydraulic fluid discharged by either or both of the first discharge step and the second discharge step. [Effects of the Invention]

[0009] This disclosure provides a die-casting machine capable of effectively utilizing the energy contained in the hydraulic fluid discharged into a tank, and a method for regenerating power in a die-casting machine. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a schematic diagram showing an example of a die-casting machine. [Figure 2] Figure 2 is a schematic diagram showing an example of a circulation system in a die-casting machine. [Figure 3] Figure 3 is a flowchart showing an example of the processing flow performed by the control device. [Figure 4] Figures 4(a), 4(b), and 4(c) are schematic diagrams illustrating the internal workings of a hydraulic power source. [Figure 5] Figure 5 is a schematic diagram showing another example of a circulation system. [Figure 6] Figure 6 is a schematic diagram showing another example of a circulation system. [Modes for carrying out the invention]

[0011] An embodiment will be described below with reference to the drawings. In this description, the same elements or elements having the same function will be denoted by the same reference numeral, and redundant descriptions will be omitted.

[0012] [Die-casting machine] Figure 1 schematically shows a die-casting machine according to one embodiment. The die-casting machine 1 shown in Figure 1 is a device that manufactures castings by filling a mold with molten metal (hereinafter referred to as "molten metal") and shaping it. Molten metal is also called molten metal and is, for example, an aluminum alloy. The die-casting machine 1 is also called a die-casting device or a casting and molding device. The die-casting machine 1 comprises, for example, a casting section 10, an injection section 20, an injection cylinder 30, a hydraulic drive section 40, and a control device 100. The individual elements of the die-casting machine 1 will be described below.

[0013] The casting section 10 is the part that forms a cavity having a shape corresponding to the casting using a pair of molds. The casting section 10 has a fixed mold 11 and a movable mold 12. The fixed mold 11 and the movable mold 12 are attached to a clamping device, and the movable mold 12 is driven by a drive configuration connected to the movable mold 12, thereby clamping the fixed mold 11 and the movable mold 12 together. The drive configuration that drives the movable mold 12 may be hydraulic.

[0014] When the fixed mold 11 and the movable mold 12 are clamped together, a cavity 13 having a shape corresponding to the casting and a runner 14 communicating with the cavity 13 are formed. The cavity 13 is connected to the injection unit 20 via the runner 14 (runner 14 and gate), and molten metal is filled into the cavity 13.

[0015] The injection unit 20 is the part that guides the molten metal into the cavity 13. The molten metal fills the cavity 13 through the injection unit 20. The injection unit 20 has an injection sleeve 21, a plunger 22, and a plunger rod 23.

[0016] The injection sleeve 21 is a member that forms a space for temporarily storing molten metal. The injection sleeve 21 is, for example, formed in a cylindrical shape so as to extend in one horizontal direction. The injection sleeve 21 is provided with a pouring port 24. The die casting machine 1 supplies molten metal into the injection sleeve 21 from the pouring port 24 using a molten metal supply device or the like.

[0017] The plunger 22 is a member that moves the molten metal supplied into the injection sleeve 21 toward the cavity 13. The plunger 22 is also referred to as a plunger tip. The plunger 22 is provided so as to be capable of advancing and retreating (movable) inside the injection sleeve 21. In the present disclosure, regarding the operation of the plunger 22, the direction in which the plunger 22 approaches the cavity 13 is defined as "front" or "forward", and the operation of moving forward is defined as "advance". In addition, the direction in which the plunger 22 moves away from the cavity 13 is defined as "rear" or "rearward", the operation of moving rearward is defined as "retreat", and advance and retreat are collectively referred to as "advance and retreat". In FIG. 1, the front (forward) direction is represented by an arrow marked with "F", and the rear (rearward) direction is represented by an arrow marked with "B".

[0018] By the advancing operation of the plunger 22, the molten metal in the injection sleeve 21 moves into the cavity 13 via the runner 14. By the retreating operation of the plunger 22, in a state where the plunger 22 is disposed rearward of the pouring port 24, the molten metal is supplied from the pouring port 24 into the injection sleeve 21.

[0019] The injection cylinder 30 is a member that injects molten metal using hydraulic fluid supplied from a hydraulic pressure source. The molten metal is injected by operating the plunger 22 of the injection unit 20. The injection cylinder 30 is a hydraulically driven cylinder. The injection cylinder 30 has a cylinder container 31, a cylinder rod 32, a connecting portion 33, and a cylinder head 34.

[0020] The cylinder container 31 forms a space for a part of the members included in the injection cylinder 30 to advance and retreat. The cylinder container 31 is, for example, formed in a cylindrical shape so as to extend along the advancing / retreating direction in which the plunger 22 operates. The front end portion (tip portion) of the cylinder rod 32 is detachably connected to the plunger rod 23 of the injection unit 20 via a connecting portion 33. A cylinder head 34 is connected to the rear end portion of the cylinder rod 32, and the cylinder rod 32 and the cylinder head 34 are integrated.

[0021] A space is formed inside the cylinder container 31 at the rear of the cylinder head 34, and this space is referred to as a "head-side hydraulic chamber 34a". A space is formed inside the cylinder container 31 at the front of the cylinder head 34, and this space is referred to as a "rod-side hydraulic chamber 32a". By controlling the flow of hydraulic oil to each of the rod-side hydraulic chamber 32a and the head-side hydraulic chamber 34a, the speed of the plunger 22 during the forward movement (injection speed) and the speed during the backward movement may be controlled.

[0022] The hydraulic drive unit 40 is a part that supplies, to the injection cylinder 30, hydraulic oil for operating the plunger 22 to perform the injection forward advance step, and hydraulic oil for increasing the pressure of the molten metal in the cavity 13. The hydraulic drive unit 40 includes, for example, a first hydraulic pressure source 41 (hydraulic pressure source), a second hydraulic pressure source 42, and a switching member 43.

[0023] The first hydraulic pressure source 41 is a supply source of hydraulic oil for injection forward advance. The first hydraulic pressure source 41 delivers hydraulic oil for operating the plunger 22 to perform the injection forward advance step to the head-side hydraulic chamber 34a of the injection cylinder 30. The first hydraulic pressure source 41 is, for example, an accumulator, and includes a sealed container 41a and an airtight member 41b. The sealed container 41a is a member that forms a space for storing hydraulic oil and gas. The airtight member 41b is accommodated in the sealed container 41a, and is provided so as to partition the interior of the sealed container 41a into two spaces.

[0024] One of the two spaces separated by the airtight member 41b contains gas, and this space is referred to as the "gas chamber 41g". The other of the two spaces contains hydraulic fluid for injection propulsion, and this space is referred to as the "hydraulic fluid chamber 41h". The airtight member 41b is movable inside the sealed container 41a, airtightly separating the gas chamber 41g and the hydraulic fluid chamber 41h. The gas chamber 41g may be filled with a predetermined amount of gas, and the gas filled in the gas chamber 41g may be nitrogen gas.

[0025] The airtight member 41b moves according to the amount of hydraulic fluid contained in the hydraulic fluid chamber 41h. As the amount of hydraulic fluid contained in the hydraulic fluid chamber 41h increases, the volume of the gas chamber 41g decreases. As a result, the pressure inside the gas chamber 41g increases, and a greater pressure is applied to the hydraulic fluid contained in the hydraulic fluid chamber 41h. Conversely, as the amount of hydraulic fluid contained in the hydraulic fluid chamber 41h decreases, the volume of the gas chamber 41g increases. Consequently, the pressure inside the gas chamber 41g decreases, and the pressure applied to the hydraulic fluid contained in the hydraulic fluid chamber 41h also decreases.

[0026] The inside of the hydraulic fluid chamber 41h is connected to the head-side hydraulic chamber 34a via a supply pipe. When high pressure is applied to the hydraulic fluid in the hydraulic fluid chamber 41h, and the passage between the hydraulic fluid chamber 41h and the head-side hydraulic chamber 34a in the flow path of the supply pipe becomes open, hydraulic fluid is delivered from the hydraulic fluid chamber 41h to the head-side hydraulic chamber 34a.

[0027] The second hydraulic source 42 is a source of hydraulic fluid for boosting pressure. After injection filling into the cavity 13, the second hydraulic source 42 delivers hydraulic fluid to the injection cylinder 30 to apply pressure to the molten metal in the cavity 13 by driving the plunger 22. The second hydraulic source 42 is, for example, an accumulator and includes a sealed container 42a and an airtight member 42b. The sealed container 42a has the same function as the sealed container 41a of the first hydraulic source 41, and the airtight member 42b has the same function as the airtight member 41b of the first hydraulic source 41.

[0028] Similar to the first hydraulic power source 41, one of the two spaces separated by the airtight member 42b contains gas, and this space is referred to as the "gas chamber 42g". The other of the two spaces contains hydraulic fluid for pressurizing, and this space is referred to as the "hydraulic fluid chamber 42h". The airtight member 42b is movable and airtightly partitions the gas chamber 42g and the hydraulic fluid chamber 42h inside the sealed container 42a. The gas chamber 42g may be filled with a predetermined amount of gas, and the gas filled in the gas chamber 42g may be nitrogen gas.

[0029] The airtight member 42b moves according to the amount of hydraulic fluid contained in the hydraulic fluid chamber 42h. As the amount of hydraulic fluid contained in the hydraulic fluid chamber 42h increases, the volume of the gas chamber 42g decreases. As a result, the pressure inside the gas chamber 41g increases, and a greater pressure is applied to the hydraulic fluid contained in the hydraulic fluid chamber 41h. On the other hand, as the amount of hydraulic fluid contained in the hydraulic fluid chamber 42h decreases, the volume of the gas chamber 42g increases. Consequently, the pressure inside the gas chamber 42g decreases, and the pressure applied to the hydraulic fluid contained in the hydraulic fluid chamber 42h also decreases.

[0030] The inside of the hydraulic fluid chamber 42h is connected to the head-side hydraulic chamber 34a via a supply pipe. When high pressure is applied to the hydraulic fluid in the hydraulic fluid chamber 42h, and the passage between the hydraulic fluid chamber 42h and the head-side hydraulic chamber 34a in the flow path of the supply pipe becomes open, hydraulic fluid is delivered from the hydraulic fluid chamber 42h to the head-side hydraulic chamber 34a.

[0031] The switching member 43 is a member that switches the connection state between the first hydraulic power source 41 and the second hydraulic power source 42 and the injection cylinder 30. The switching member 43 switches, for example, between a state in which no hydraulic fluid is supplied to the injection cylinder 30 from both the first hydraulic power source 41 and the second hydraulic power source 42, and a state in which hydraulic fluid is supplied to the injection cylinder 30 from either the first hydraulic power source 41 or the second hydraulic power source 42. The switching member 43 may further switch between a state in which no hydraulic fluid is supplied from the second hydraulic power source 42 and hydraulic fluid is supplied to the injection cylinder 30 from the first hydraulic power source 41 and hydraulic fluid is supplied to the injection cylinder 30 from the second hydraulic power source 42.

[0032] The switching member 43 can be any member as long as it can switch the supply state of hydraulic fluid to the injection cylinder 30, and may consist of one or more valves. The switching member 43 operates based on an operation instruction from the control device 100.

[0033] (circulation device) As shown in Figure 2, the die-casting machine 1 is equipped with a circulation device 50. The circulation device 50 is a device that circulates hydraulic fluid at least between the first hydraulic power source 41 and the second hydraulic power source 42 and the tank 52, and between the injection cylinder 30 and the tank 52. The tank 52 of the circulation device 50 is a component that stores hydraulic fluid. The tank 52 may be composed of one or more containers capable of holding hydraulic fluid.

[0034] The circulation device 50 has a hydraulic source return pipe 62. The hydraulic source return pipe 62 connects the first hydraulic source 41 and the tank 52, and is a pipe that returns the hydraulic fluid discharged from the first hydraulic source 41 to the tank 52. In addition to the first hydraulic source 41, the hydraulic source return pipe 62 may also connect a second hydraulic source 42 to the tank 52, and the hydraulic fluid discharged from the second hydraulic source 42 may be returned to the tank 52. For example, after the operation of the die-casting machine 1 has finished, the hydraulic fluid remaining in the first hydraulic source 41 and the second hydraulic source 42, respectively, is guided to the tank 52 via the hydraulic source return pipe 62.

[0035] The circulation device 50 has a switching member 64. The switching member 64 is a member that switches the connection state between the first hydraulic power source 41 and the second hydraulic power source 42 and the tank 52. The switching member 64 is provided so that, for example, when the operation of the die-casting machine 1 ends, the flow paths between both the first hydraulic power source 41 and the second hydraulic power source 42 and the tank 52 can be opened. The switching member 64 may be able to switch between a state in which hydraulic fluid is not led from the second hydraulic power source 42 to the tank 52 and hydraulic fluid is returned from the first hydraulic power source 41 to the tank 52, and a state in which hydraulic fluid is not led from the first hydraulic power source 41 to the tank 52 and hydraulic fluid is returned from the second hydraulic power source 42 to the tank 52. The switching member 64 may be composed of one or more valves.

[0036] The circulation device 50 has one or more hydraulic configuration return pipes 69. The circulation device 50 has, for example, N (where N is an integer of 2 or more) hydraulic configuration return pipes 69. The N hydraulic configuration return pipes 69 are pipes for returning the hydraulic fluid discharged from hydraulic configurations Hd1 to HdN (N hydraulic configurations) to the tank 52. Each of the hydraulic configurations Hd1 to HdN is a configuration for driving components other than the injection cylinder 30 in the die-casting machine 1, and includes, for example, a hydraulic cylinder. The downstream end of the hydraulic configuration return pipe 69 is connected to the hydraulic source return pipe 62, and the hydraulic fluid from the hydraulic configuration return pipe 69 is returned to the tank 52 via the hydraulic source return pipe 62.

[0037] The circulation device 50 has an injection cylinder return pipe 66. The injection cylinder return pipe 66 connects the injection cylinder 30 and the tank 52, and is a pipe that returns the hydraulic fluid discharged from the injection cylinder 30 to the tank 52. For example, the injection cylinder return pipe 66 connects the rod-side hydraulic chamber 32a and the tank 52, and returns the hydraulic fluid discharged from the rod-side hydraulic chamber 32a to the tank 52. In one example, each time an injection advancement process is performed to obtain a casting, the hydraulic fluid discharged from the rod-side hydraulic chamber 32a is guided to the tank 52 via the injection cylinder return pipe 66 during the execution of that injection advancement process. The connection between the injection cylinder return pipe 66 and the tank 52 may be switched open or closed by a switching member 78, which will be described later.

[0038] The hydraulic source return pipe 62 and the injection cylinder return pipe 66 may merge at a junction 70 before the tank 52. "Before the tank 52" means a location upstream of the tank 52. In this disclosure, the terms "upstream" and "downstream" are used in reference to the movement of the hydraulic fluid. That is, the hydraulic fluid moves (flows) from upstream to downstream. The junction 70 and the tank 52 may be connected by a single pipe.

[0039] The hydraulic source return piping 62 consists of piping connecting the first hydraulic source 41 and the junction 70, and piping connecting the junction 70 and the tank 52. The injection cylinder return piping 66 consists of piping connecting the injection cylinder 30 and the junction 70, and piping connecting the junction 70 and the tank 52. Between the hydraulic source return piping 62 and the injection cylinder return piping 66, one pipe is used in common in the section downstream of the junction 70.

[0040] The circulation device 50 includes a hydraulic power supply pipe 72, a hydraulic power supply pump 73, and a switching member 74. The hydraulic power supply pipe 72 is a pipe for supplying (replenishing) hydraulic fluid from the tank 52 to the first hydraulic power source 41 and the second hydraulic power source 42, respectively. As illustrated in Figure 2, in the hydraulic power supply pipe 72, one pipe connected to the tank 52 may branch into two pipes midway and then be connected to the first hydraulic power source 41 and the second hydraulic power source 42, respectively. The hydraulic power supply pump 73 is a device that pumps hydraulic fluid from the tank 52 to either the first hydraulic power source 41 or the second hydraulic power source 42. In one example, each time a process including injection forward and pressure boosting to obtain one casting is performed, hydraulic fluid is supplied (replenished) from the tank 52 to the first hydraulic power source 41, and each time the process including injection forward and pressure boosting is performed multiple times, hydraulic fluid is supplied (replenished) from the tank 52 to the second hydraulic power source 42.

[0041] The switching member 74 is a member that switches the connection state between the tank 52 and the first hydraulic source 41 and the second hydraulic source 42 with respect to the connection via the hydraulic source supply piping 72. The switching member 74 can switch, for example, between a state in which the tank 52 is not connected to both the first hydraulic source 41 and the second hydraulic source 42 (a state in which no power can be supplied from the tank 52) and a state in which the tank 52 is connected to either the first hydraulic source 41 or the second hydraulic source 42 (a state in which power can be supplied from the tank 52). The switching member 74 may further switch between a state in which the first hydraulic source 41 is connected to the tank 52 but the second hydraulic source 42 is not connected, and a state in which the second hydraulic source 42 is connected to the tank 52 but the first hydraulic source 41 is not connected. The switching member 74 may be composed of one or more valves.

[0042] The circulation device 50 includes an injection cylinder supply pipe 76, an injection cylinder supply pump 77, and a switching member 78. The injection cylinder supply pipe 76 is a pipe for supplying hydraulic fluid to the injection cylinder 30. The injection cylinder supply pipe 76 may merge with the upstream section of the injection cylinder return pipe 66 and then be connected to the rod-side hydraulic chamber 32a. The injection cylinder supply pump 77 is a device that pumps hydraulic fluid from the tank 52 towards the rod-side hydraulic chamber 32a. In one example, each time a process including injection forward and pressure boosting is performed to obtain one casting, hydraulic fluid is supplied from the tank 52 to the rod-side hydraulic chamber 32a in order to retract the cylinder head 34.

[0043] The switching member 78 is a member that switches the connection state between the injection cylinder 30 and the tank 52 with respect to the connection via the injection cylinder return pipe 66 and the injection cylinder supply pipe 76. The switching member 78 may, for example, be able to switch between a state in which the tank 52 and the rod-side hydraulic chamber 32a are connected via the injection cylinder return pipe 66 (a state in which hydraulic fluid is returned to the tank 52) and a state in which the tank 52 and the rod-side hydraulic chamber 32a are connected via the injection cylinder supply pipe 76 (a state in which hydraulic fluid can be supplied to the rod-side hydraulic chamber 32a). The switching member 78 may be composed of one or more valves.

[0044] The switching member 78 may function as a valve for controlling the speed of the plunger 22 when performing the injection forward stroke. The switching member 78 adjusts the amount of hydraulic fluid discharged from the rod-side hydraulic chamber 32a by adjusting its opening degree, for example, when the rod-side hydraulic chamber 32a and the tank 52 are connected via the injection cylinder return pipe 66. In this way, the speed of the plunger 22 may be controlled by adjusting the discharge amount of hydraulic fluid from the rod-side hydraulic chamber 32a (i.e., meter-out control may be performed).

[0045] (Regenerative power generation means) The circulation device 50 has a regenerative power generation means 80. The regenerative power generation means 80 is a means (device) for generating electricity by regenerating the fluid energy of the hydraulic fluid. The regenerative power generation means 80 generates electricity by utilizing the fluid energy of the hydraulic fluid as it returns to the tank 52. In one example, mechanical energy is generated by the energy of the hydraulic fluid flowing in the piping (converting fluid energy into mechanical energy), and that mechanical energy is converted into electrical energy.

[0046] The regenerative power generation means 80 is provided in either the hydraulic source return pipe 62 or the injection cylinder return pipe 66, or both. In the example shown in Figure 2, the regenerative power generation means 80 is provided in both the hydraulic source return pipe 62 and the injection cylinder return pipe 66. When the regenerative power generation means 80 is provided in both the hydraulic source return pipe 62 and the injection cylinder return pipe 66, the regenerative power generation means 80 may be provided between the confluence section 70 and the tank 52. In other words, the regenerative power generation means 80 may be provided in the piping downstream of the confluence section 70, which is used in common between the hydraulic source return pipe 62 and the injection cylinder return pipe 66.

[0047] The regenerative power generation means 80 includes, for example, a converter 82 and a generator 84. The converter 82 is a device that generates rotational energy from the flow of hydraulic fluid in a pipe. That is, the converter 82 converts the fluid energy of the hydraulic fluid into rotational energy. The converter 82 may also be a turbine. The generator 84 is connected to the converter 82 and is a device that generates electricity using the rotational energy generated by the converter 82. That is, the generator 84 converts the rotational energy generated by the converter 82 into electrical energy.

[0048] In the die-casting machine 1, at least a portion of the hydraulic source return piping 62 and at least a portion of the injection cylinder return piping 66 may be exposed in a manner visible to workers or the like. The conversion device 82 of the regenerative power generation means 80 may be provided in the exposed sections of the hydraulic source return piping 62 and the injection cylinder return piping 66.

[0049] The power generated by the generator 84 may be used in any way. The power generated by the generator 84 may be used in the die-casting machine 1, in devices other than the die-casting machine 1, or output to an external power system. The operation of at least some of the components included in the circulation device 50 may be controlled by the control device 100.

[0050] The control device 100 includes, for example, a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), and an input / output interface as its hardware configuration. The control device 100 is composed of, for example, one or more computers. If the control device 100 is composed of multiple computers, these computers may be connected to each other in a way that allows them to communicate with one another.

[0051] [Power regeneration method in die-casting machines] Next, a power recovery method performed in die-casting machine 1 (power recovery method in die-casting machine) will be described. This power recovery method includes at least a first discharge step, a second discharge step, and a power generation step.

[0052] The first discharge process is the process of returning the hydraulic fluid discharged from the first hydraulic source 41 and the second hydraulic source 42 to the tank 52. In the first discharge process, for example, the hydraulic fluid is returned from the first hydraulic source 41 and the second hydraulic source 42 to the tank 52 via the hydraulic source return pipe 62. The second discharge process is the process of returning the hydraulic fluid discharged from the injection cylinder 30 to the tank 52. In the second discharge process, for example, the hydraulic fluid is returned from the rod-side hydraulic chamber 32a of the injection cylinder 30 to the tank 52 via the injection cylinder return pipe 66.

[0053] The power generation process is a process of generating electricity by regenerating the fluid energy of the hydraulic fluid discharged in either or both of the first discharge process and the second discharge process. In the power generation process, for example, when the first discharge process is performed, electricity is generated using the fluid energy of the hydraulic fluid discharged from the first hydraulic power source 41, and when the second discharge process is performed, electricity is generated using the fluid energy of the hydraulic fluid discharged from the injection cylinder 30. In the power generation process, power generation (regeneration) may also be performed from the flow of hydraulic fluid in the piping by a regenerative power generation means 80 provided in the piping.

[0054] Figure 3 illustrates the processing flow executed by the control device 100 in the power regeneration method. This processing flow is executed in parallel while the control for repeatedly obtaining castings by the die-casting machine 1 continues. Figures 4(a), 4(b), and 4(c) schematically illustrate the state inside the sealed container 41a of the first hydraulic power source 41 while the processing flow is being executed. In Figure 4(a), etc., "Gn" indicates that nitrogen gas is filling the gas chamber 41g.

[0055] As the injection advancement process is carried out using hydraulic fluid from the first hydraulic source 41, the amount of hydraulic fluid in the hydraulic fluid chamber 41h decreases, as shown in Figure 4(b), and the gas chamber 41g expands accordingly, resulting in a decrease in pressure compared to before the injection advancement process (Figure 4(a)). On the other hand, the amount of hydraulic fluid in the first hydraulic source 41 is set in advance by adding a margin to the amount discharged in one injection advancement process. That is, even after the completion of one injection advancement process, the amount of hydraulic fluid in the first hydraulic source 41 does not become completely zero, and a certain amount of hydraulic fluid is ensured. Therefore, even after the completion of the injection advancement process, hydraulic fluid remains in the first hydraulic source 41, and pressure is applied from the gas chamber 41g.

[0056] After the die-casting machine 1 starts operation, the control device 100 executes step S01. Before executing step S01, the first hydraulic power source 41 and the second hydraulic power source 42 are pre-filled with hydraulic fluid. For example, in the first hydraulic power source 41, as shown in Figure 4(a), the hydraulic fluid chamber 41h is replenished with enough hydraulic fluid to enable injection forward movement. In this state, high pressure is applied to the hydraulic fluid by the compression of gas Gn in the gas chamber 41g. (Step S01: Injection advancement process) In step S01, if a command is received from the control device 100, the injection advancement process is executed by the operating hydraulic pressure from the first hydraulic power source 41, which advances the plunger 22 and injects the molten metal into the cavity 13.

[0057] (Step S02: Regeneration in the second discharge process) Next, the control device 100 executes step S02. In step S02, the hydraulic fluid is discharged from the rod-side hydraulic chamber 32a to the tank 52. The fluid energy of the hydraulic fluid during this discharge is used to regenerate power in the regenerative power generation means 80 (the second discharge step and power generation step described above). For example, the control device 100 controls the switching member 78 so that the hydraulic fluid discharged from the rod-side hydraulic chamber 32a via the injection cylinder return pipe 66 returns to the tank 52. Following the execution of step S02, for example, the regenerative power generation means 80, which is located downstream of the confluence section 70, generates electricity using the energy of the hydraulic fluid flowing through the injection cylinder return pipe 66.

[0058] (Step S03: Pressure boosting process) In step S03, it is determined whether or not the pressure boosting process has been executed based on the operating hydraulic pressure of the second hydraulic source 42. If the pressure boosting process is completed, the process proceeds to step S04. (Step S04: Injection retraction process) In step S04, the injection retraction process is performed. The hydraulic fluid from the tank 52 is supplied to the rod-side hydraulic chamber 32a of the injection cylinder 30 via the injection cylinder supply pump 77 and the switching member 78, thereby moving the cylinder head 34 to the retracted side.

[0059] (Step S05: Determination of machine operation termination) Next, the control device 100 executes step S05. In step S05, for example, the control device 100 determines whether or not the operation of the die-casting machine 1 has ended. In one example, the control device 100 determines that the operation of the die-casting machine 1 has ended when it receives a user instruction indicating the end of the operation of the die-casting machine 1. Note that the operation of the die-casting machine 1 may be performed on a daily basis.

[0060] If it is determined in step S05 that the operation of the die-casting machine 1 has not finished (step S05: NO), the control device 100 proceeds to step S06. In step S06, for example, the control device 100 controls the hydraulic power supply pump 73 and the switching member 74 so that hydraulic fluid is replenished to the first hydraulic power source 41 via the hydraulic power supply piping 72. As a result, the first hydraulic power source 41 returns to the state illustrated in Figure 4(a). Thereafter, the control device 100 repeats the series of processes from steps S01 to S05. As step S02 is repeated, electricity is generated by the regenerative power generation means 80 each time hydraulic fluid is discharged from the rod-side hydraulic chamber 32a.

[0061] (Step S07: Regeneration in the first discharge process) On the other hand, if it is determined in step S05 that the operation of the die-casting machine 1 has ended (step S05: YES), the control device 100 proceeds to step S07. In step S07, for example, the control device 100 controls the switching member 64 to return the hydraulic fluid remaining in the hydraulic fluid chambers 41h and 42h to the tank 52 via the hydraulic source return pipe 62. Regeneration is performed by the regenerative power generation means 80 using the fluid energy of the hydraulic fluid during this discharge (the first discharge step and power generation step described above). At this time, as shown in Figure 4(c), hydraulic fluid may be returned to the tank 52 from the first hydraulic source 41 and the second hydraulic source 42 so that no hydraulic fluid remains in the first hydraulic source 41.

[0062] When the operation of the die-casting machine 1 is terminated, hydraulic fluid remains in the first hydraulic source 41 and the second hydraulic source 42. If gas-type accumulators are used as the first hydraulic source 41 and the second hydraulic source 42, the gas pressure also acts on the remaining hydraulic fluid, and it may become high pressure. Therefore, if the operation of the die-casting machine 1 is terminated without draining the hydraulic fluid from the first hydraulic source 41 and the second hydraulic source 42, high-pressure hydraulic fluid will remain, which may cause problems. Therefore, in this invention, when the operation of the die-casting machine 1 ends, the hydraulic fluid from the first hydraulic source 41 and the second hydraulic source 42 is discharged into the tank 52, thereby avoiding the machine being shut down while high-pressure hydraulic fluid remains.

[0063] [Differentiation] The processing flow shown in Figure 3 is an example and can be modified as appropriate. In the above processing flow, one step and the next step may be executed in parallel, and several steps may be executed in a different order than the example above. In place of at least some of the steps in the above processing flow, or in addition to the above processing flow, steps with content different from the example above may be executed.

[0064] As shown in Figure 5, the die-casting machine 1 may be equipped with a circulation device 50A instead of the circulation device 50. The circulation device 50A differs from the circulation device 50 in that it has a first regenerative power generation means 80a and a second regenerative power generation means 80b instead of the regenerative power generation means 80. Each of the first regenerative power generation means 80a and the second regenerative power generation means 80b may be configured similarly to the regenerative power generation means 80, and may include, for example, a converter 82 and a generator 84.

[0065] The first regenerative power generation means 80a is provided between the confluence section 70 and the first hydraulic power source 41 in the hydraulic power source return pipe 62. The second regenerative power generation means 80b is provided between the confluence section 70 and the injection cylinder 30 in the injection cylinder return pipe 66. As described above, when regenerative power generation means (80a, 80b) are provided in both the hydraulic power source return pipe 62 and the injection cylinder return pipe 66, the regenerative power generation means (80a, 80b) may be provided in the section upstream of the confluence section 70 in both the hydraulic power source return pipe 62 and the injection cylinder return pipe 66, respectively.

[0066] As shown in Figure 6, the die-casting machine 1 may be equipped with a circulation device 50B instead of the circulation device 50. The circulation device 50B differs from the circulation device 50 in that it has one or more hydraulic return pipes 89 and has another regenerative power generation means in addition to the regenerative power generation means 80. Note that in Figure 6, some of the circulation device shown in Figure 2 is omitted for space reasons. The circulation device 50B has, for example, M (where M is an integer of 2 or more) hydraulic return pipes 89.

[0067] The M hydraulic configuration return pipes 89 are pipes for returning the hydraulic fluid discharged from the hydraulic configurations Hd11 to Hd1M (M hydraulic configurations) back to the tank 52. Each of the hydraulic configurations Hd11 to Hd1M is a configuration for driving components other than the injection cylinder 30 in the die-casting machine 1, and includes, for example, a hydraulic cylinder. Unlike the hydraulic configuration return pipes 69 described above, the hydraulic configuration return pipes 89 guide the hydraulic fluid from the hydraulic configuration to the tank 52 without passing through the hydraulic source return pipe 62. If one or more hydraulic configuration return pipes 89 are provided, one or more hydraulic configuration return pipes 69 may also be provided, or one or more hydraulic configuration return pipes 69 may not be provided.

[0068] The circulation device 50B has one or more regenerative power generation means in addition to the regenerative power generation means 80. The circulation device 50B may have regenerative power generation means 821 to 82M (M other regenerative power generation means) corresponding to the hydraulic configurations Hd11 to Hd1M. Each of the regenerative power generation means 821 to 82M may be configured similarly to the regenerative power generation means 80, and for example, includes a converter 82 and a generator 84. One of the regenerative power generation means 82m (where m is any integer from 1 to M) among the regenerative power generation means 821 to 82M generates electricity by regenerating the fluid energy of the hydraulic fluid flowing from the corresponding hydraulic configuration Hd1m through the hydraulic configuration return pipe 89 toward the tank 52.

[0069] In the circulation devices 50, 50A, and 50B, the hydraulic source return pipe 62 and the injection cylinder return pipe 66 may be connected to the tank 52 without merging. In this case, a regenerative power generation means 80 may be provided in either the hydraulic source return pipe 62 or the injection cylinder return pipe 66, or a regenerative power generation means 80 may be provided in each of the hydraulic source return pipe 62 and the injection cylinder return pipe 66.

[0070] In the circulation devices 50, 50A, and 50B, the injection cylinder return pipe 66 and the injection cylinder supply pipe 76 may be connected to the head-side hydraulic chamber 34a independently of each other, without merging via the switching member 78.

[0071] In the circulation devices 50, 50A, and 50B, the injection cylinder return pipe 66 may be a pipe that returns the hydraulic fluid discharged from the head-side hydraulic chamber 34a to the tank 52 instead of the rod-side hydraulic chamber 32a. The injection cylinder return pipe 66 may also be a pipe that leads the hydraulic fluid from the rod-side hydraulic chamber 32a and the head-side hydraulic chamber 34a, respectively, to the tank 52. Two independent injection cylinder return pipes 66 may be provided, each connecting the rod-side hydraulic chamber 32a and the head-side hydraulic chamber 34a to the tank 52. In this case, a regenerative power generation means 80 may be provided for each of the two injection cylinder return pipes 66.

[0072] In one of the various examples described above, at least some of the matters described in another example may be combined.

[0073] [Summary of this disclosure] The die-casting machine (1) described above includes a hydraulic power source (41), an injection cylinder (30) that injects molten metal using hydraulic fluid supplied from the hydraulic power source (41), a tank for storing the hydraulic fluid, a hydraulic power source return pipe (62) that connects the hydraulic power source (41) and the tank (52) and returns the hydraulic fluid discharged from the hydraulic power source (41) to the tank (52), and an injection cylinder return pipe (66) that connects the injection cylinder (30) and the tank (52) and returns the hydraulic fluid discharged from the injection cylinder (30) to the tank (52). In the die-casting machine (1), regenerative power generation means (80, 80a, 80b) that regenerates the fluid energy of the hydraulic fluid to generate electricity is provided in either the hydraulic power source return pipe (62) or the injection cylinder return pipe (66) or both.

[0074] [i] In a die-casting machine (1), the hydraulic fluid discharged from the injection cylinder (30) is returned to the tank (52) via a return pipe. However, when the plunger is operated by the injection cylinder (30), the hydraulic fluid discharged, especially when the plunger moves forward (moving the plunger to remove air from the sleeve), is not at a very high pressure because it is released into the tank (52). However, since the hydraulic fluid is discharged each time the injection cylinder (30) is driven in the forward and backward directions, the flow rate is large. Consequently, a large amount of energy is generated. Conventionally, this energy was not utilized and the hydraulic fluid was simply discharged into the tank (52). In contrast, by installing a regenerative power generation means (80, 80b) in the injection cylinder return pipe (66), electricity can be generated from energy that was previously unused, thereby improving energy efficiency. [ii] In addition, an accumulator is generally used as the hydraulic source (41) in a die-casting machine (1). When the die-casting machine (1) is shut down (stopped from operation), the hydraulic fluid in the accumulator is often returned to the tank. The hydraulic fluid returned from the accumulator has a large amount of energy (because it is pressurized in the accumulator and therefore has a large amount of energy). Therefore, energy efficiency can be similarly improved by providing a regenerative power generation means (80, 80a) in the hydraulic source return piping (62). [iii] As described above, in a die-casting machine (1) in which a regenerative power generation means is provided in at least one of the hydraulic source return pipe (62) and the injection cylinder return pipe (66), it is possible to effectively utilize the energy contained in the hydraulic fluid discharged into the tank (52).

[0075] In the die-casting machine (1) described above, the hydraulic source return pipe (62) and the injection cylinder return pipe (66) may merge at the confluence (70) before the tank (52). If regenerative power generation means (80) are provided for both the hydraulic source return pipe (62) and the injection cylinder return pipe (66), the regenerative power generation means (80) may be provided between the confluence (70) and the tank (52).

[0076] In this case, the energy contained in the hydraulic fluid discharged from both the hydraulic source return pipe (62) and the injection cylinder return pipe (66) can be effectively utilized while avoiding the complexity of the equipment associated with the installation of regenerative power generation means.

[0077] In the die-casting machine (1) described above, the hydraulic source return pipe (62) and the injection cylinder return pipe (66) may merge at the confluence (70) before the tank (52). If regenerative power generation means (80a, 80b) are provided for both the hydraulic source return pipe (62) and the injection cylinder return pipe (60), the regenerative power generation means (80a, 80b) may be provided for each of the hydraulic source return pipe (62) and the injection cylinder return pipe (66) in a section upstream of the confluence (70).

[0078] Compared to the downstream section of the confluence (70), the upstream section of the confluence (70) experiences less pressure loss due to flow within the piping. As described above, by providing regenerative power generation means in both the hydraulic source return pipe (62) and the injection cylinder return pipe (66) in the upstream section of the confluence (70), energy efficiency can be further improved.

[0079] The power regeneration method described above is performed in a die-casting machine (1) that includes a hydraulic power source (41), an injection cylinder (30) that injects molten metal using hydraulic fluid supplied from the hydraulic power source (41), and a tank (52) that stores the hydraulic fluid. This power regeneration method includes a first discharge step of returning the hydraulic fluid discharged from the hydraulic power source (41) to the tank (52), a second discharge step of returning the hydraulic fluid discharged from the injection cylinder (30) to the tank (52), and a power generation step of generating electricity. The power generation step generates electricity by regenerating the fluid energy of the hydraulic fluid discharged in either the first discharge step or the second discharge step, or both.

[0080] [i] By generating electricity using the hydraulic fluid discharged from the injection cylinder (30) in the second discharge process, previously unused energy can be utilized, thereby improving energy efficiency. [ii] Similarly, by generating electricity using the hydraulic fluid discharged from the hydraulic source (41) in the second discharge process, energy efficiency can be improved. From the above, in the power regeneration method described above, which generates electricity based on the fluid energy of the hydraulic oil discharged in at least one of the first discharge process and the second discharge process, it is possible to effectively utilize the energy contained in the hydraulic oil discharged into the tank (52). [Explanation of Symbols]

[0081] 1…Die-casting machine, 30…Injection cylinder, 41…First hydraulic power source, 42…Second hydraulic power source, 52…Tank, 62…Hydraulic power source return piping, 66…Injection cylinder return piping, 80…Regenerative power generation means, 80a…First regenerative power generation means, 80b…Second regenerative power generation means.

Claims

1. Hydraulic power source, An injection cylinder that injects molten metal using hydraulic fluid supplied from the aforementioned hydraulic source, A tank for storing the aforementioned hydraulic fluid, A hydraulic source return pipe connects the hydraulic source and the tank, and returns the hydraulic fluid discharged from the hydraulic source back to the tank, The injection cylinder and the tank are connected, and the injection cylinder return pipe returns the hydraulic fluid discharged from the injection cylinder back to the tank. In a die-casting machine equipped with, Regenerative power generation means for generating electricity by regenerating the fluid energy of the hydraulic fluid is provided in either or both of the hydraulic source return pipe and the injection cylinder return pipe. A die-casting machine characterized by the following.

2. In the die-casting machine described in claim 1, The hydraulic power source return pipe and the injection cylinder return pipe merge at the confluence before the tank. If the regenerative power generation means is provided in both the hydraulic source return pipe and the injection cylinder return pipe, the regenerative power generation means is provided between the confluence and the tank. A die-casting machine characterized by the following.

3. In the die-casting machine described in claim 1, The hydraulic power source return pipe and the injection cylinder return pipe merge at the confluence before the tank. If the regenerative power generation means is provided in both the hydraulic source return pipe and the injection cylinder return pipe, the regenerative power generation means is provided in each of the hydraulic source return pipe and the injection cylinder return pipe in a section upstream of the confluence. A die-casting machine characterized by the following.

4. A power regeneration method performed in a die-casting machine comprising a hydraulic power source, an injection cylinder for injecting molten metal using hydraulic fluid supplied from the hydraulic power source, and a tank for storing the hydraulic fluid, A first discharge step of returning the hydraulic fluid discharged from the hydraulic source back to the tank, A second discharge step involves returning the hydraulic fluid discharged from the injection cylinder to the tank, The power generation process that generates electricity and Includes, The power generation process involves generating electricity by regenerating the fluid energy of the hydraulic fluid discharged by either or both of the first discharge process and the second discharge process. A power regeneration method for die-casting machines, characterized by the following.

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