Injection Unit and Molding Machine

Abstract

To provide a hybrid injector in a novel form.SOLUTION: An injector 9 comprises an injection cylinder 27, a hydraulic unit 43, a second motor 31B and a control unit 5. The injection cylinder 27 is coupled to a plunger 21 to force out a molding material M into a metal mold 101. Also, the injection cylinder 27 has a pressure-intensifying piston 41 movable frontward and rearward. The hydraulic unit 43 feeds working liquid to the injection cylinder 27. The second motor 31B is coupled to the pressure-intensifying piston 41. The control unit 5 controls the hydraulic unit 43 and the second motor 31B to give a forward, first force by working liquid and a backward, second force by the second motor 31B smaller than the first force at the same time to the pressure-intensifying piston 41, thereby moving the pressure-intensifying piston 41 forward.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present disclosure relates to an injection device and a molding machine including the injection device. The molding machine is, for example, a die casting machine for molding metal or an injection molding machine for molding resin. [Background technology]

[0002] As an injection device that pushes out molding material into a mold using a plunger, a so-called hybrid type is known in which the plunger is driven by a hydraulic (e.g., hydraulic) drive unit and an electric drive unit (e.g., Patent Documents 1 to 3 below). Such an injection device has an injection cylinder connected to the plunger, and an electric motor connected to a member (e.g., a piston) of the injection cylinder. During an appropriate period during injection, the drive force generated by supplying hydraulic fluid to the injection cylinder and the drive force of the electric motor act simultaneously on the plunger in the same direction (e.g., the direction in which the plunger faces the mold), or one of them is selectively used. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2008-155280 A [Patent Document 2] JP 2006-315071 A [Patent Document 3] JP 2014-18840 A Summary of the Invention [Problem to be solved by the invention]

[0004] Various conventional hybrid injection devices each have advantages and disadvantages. On the other hand, user requirements are diverse. Therefore, an injection device that can satisfy the user requirements is not necessarily provided to the user. In view of the above, it is desirable to provide a new type of hybrid injection device to enrich the technology and, in turn, to increase the probability that the user requirements are satisfied.

[0005] Examples of user requirements (problems) are given below. However, the technology according to the present disclosure does not necessarily have to be able to solve the problems exemplified below.

[0006] In general, the use of an electric drive unit can save energy compared to the use of a hydraulic drive unit. This is expected to result in a reduction in carbon dioxide emissions. In addition, an electric drive unit can be controlled with higher precision than a hydraulic drive unit. For these reasons, there is a high demand for electrification in injection devices as well.

[0007] After the molding material is filled into the mold, the injection device may perform a pressure boosting process to increase the pressure applied to the molding material by the plunger, and a pressure holding process to maintain the pressure increased by the pressure boosting process. By the pressure boosting and pressure holding process, for example, porosity (voids on the surface or inside of the product) that occurs due to the shrinkage of the molding material that is cooled in the mold is reduced.

[0008] Increasing pressure and maintaining pressure require a relatively large driving force and maintaining the driving force. Therefore, when increasing pressure and maintaining pressure are performed by an electric motor, the electric motor becomes larger and consumes more power. As a result, for example, a mismatch occurs with the user's demand to reduce energy consumption by using an electric motor. In addition, it is not possible to meet the user's demand to be able to set the pressure maintaining time longer. [Means for solving the problem]

[0009] An injection device according to one embodiment of the present disclosure includes an injection cylinder connected to a plunger that pushes molding material into a mold, the injection cylinder having a piston movable in a first direction and a second direction opposite thereto, a hydraulic device that supplies hydraulic fluid to the injection cylinder, an electric motor connected to the piston, and a control device that controls the hydraulic device and the electric motor to simultaneously apply to the piston a first force in the first direction by the hydraulic fluid and a second force in the second direction by the electric motor that is smaller than the first force, thereby moving the piston in the first direction.

[0010] A molding machine according to one aspect of the present disclosure includes the above-mentioned injection device and a mold clamping device that holds the mold. Effect of the Invention

[0011] According to the above configuration, there is provided an injection device and a molding machine of a new mode in which the force of the electric motor is applied in the opposite direction to the force of the hydraulic fluid, while the piston is moved in the direction of the force of the hydraulic fluid. [Brief description of the drawings]

[0012] [Figure 1] 5A to 5C are schematic diagrams for explaining an outline of the operation of the injection device according to the embodiment. [Diagram 2] FIG. 2 is a schematic diagram for explaining the continuation of FIG. 1. [Diagram 3] FIG. 3 is a schematic diagram for explaining the continuation of FIG. 2. [Figure 4] FIG. 4 is a schematic diagram for explaining the continuation of FIG. 3; [Diagram 5] FIG. 5 is a schematic diagram for explaining the continuation of FIG. 4. [Figure 6] FIG. 2 is a side view showing the configuration of a main part of the die casting machine according to the embodiment. [Figure 7] FIG. 7 is a top view showing the configuration of a main part of the die casting machine of FIG. 6. [Figure 8] 7 is a cross-sectional view showing a schematic configuration of a main part of an injection device of the die casting machine of FIG. 6. [Figure 9] FIG. 7 is a circuit diagram showing an example of a hydraulic device of the die casting machine of FIG. 6. [Figure 10] 7A to 7C are diagrams illustrating the operation of an injection device of the die casting machine of FIG. 6. [Figure 11] 7A to 7C are diagrams illustrating a modified example of the operation of the injection device of the die casting machine of FIG. 6. [Figure 12] 12(a) to 12(c) are diagrams illustrating an injection device according to a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] <Outline of die casting machine operation> 1 to 5 are schematic diagrams for explaining an overview of an example of the operation relating to injection of the die-casting machine 1 according to the embodiment. The operation relating to injection progresses in order from Fig. 1 to Fig. 5. In the following description, for convenience, the left side of these figures may be referred to as the front, and the right side of these figures may be referred to as the rear.

[0014] The die-casting machine 1 is configured as a device that manufactures a product (molded product, die-cast product) made of solidified molding material M, for example, by injecting (filling) molten molding material M into the inside (cavity 107) of a mold 101.

[0015] The procedure for injecting the molding material M into the cavity 107 is as follows. As shown in FIG. 1, the molding material M is supplied into the sleeve 19 that communicates with the cavity 107. Then, as shown in FIGS. 1 to 3, the molding material M in the sleeve 19 is pushed out into the cavity 107 by the plunger 21. That is, injection in the narrow sense is performed. Next, the molding material M is pressed by the plunger 21, thereby increasing the pressure (FIG. 4). That is, pressure is increased. Thereafter, the molding material M is maintained in a state in which the pressure is increased (FIG. 5). That is, pressure is maintained. During pressure maintenance, the molding material M loses heat to the mold 101 and solidifies.

[0016] In order to realize the above-mentioned drive of the plunger 21, the following operations are carried out in the die casting machine 1.

[0017] First, as shown by an arrow a1 in FIG. 2, hydraulic fluid (e.g., oil) is supplied from the accumulator 47 to the rear (head side chamber 35h) of the injection piston 37. This causes the injection piston 37 to move forward. As a result, the plunger 21 connected to the injection piston 37 moves forward. As a result, injection (in the narrow sense) is performed.

[0018] Next, as shown by arrow a2 in Fig. 3, before the injection (in the narrow sense) is completed, the working fluid in the accumulator 47 is also supplied to the rear of the booster piston 41 (rear chamber 35a). That is, the booster piston 41 receives a forward force from the working fluid. On the other hand, as shown by arrow a3, the booster piston 41 receives a rearward force from the electric motor 31. The rearward force from the electric motor 31 is greater than the forward force from the working fluid. Therefore, the booster piston 41 does not move forward (is stopped).

[0019] 4, as represented by drawing the arrow a4 smaller than the arrow a3 in FIG. 3, the rearward force applied by the electric motor 31 to the booster piston 41 is made smaller than the forward force applied by the working fluid to the booster piston 41. As a result, the booster piston 41 starts to move forward. That is, the booster piston 41 does not start to move forward due to the start of the supply of working fluid to the rear of the booster piston 41 (or, from another perspective, the opening operation of a valve not shown), but starts to move forward due to the driving force of the electric motor 31 being reduced.

[0020] At the time when the booster piston 41 starts to advance, or at the time before or after that, the discharge of the working fluid from the head side chamber 35h is prohibited. Then, the booster piston 41 transmits the force received from the working fluid in the rear (rear side chamber 35a) to the working fluid in the head side chamber 35h. Here, the area (pressure receiving area) of the booster piston 41 that receives pressure from the working fluid in the rear side chamber 35a is larger than the area that receives pressure from the working fluid in the head side chamber 35h. Therefore, the booster piston 41 can increase the pressure applied from the accumulator 47 to the rear side chamber 35a and apply it to the head side chamber 35h. As a result, the pressure applied by the plunger 21 to the molding material M increases, and pressure is increased.

[0021] During pressure increase, the driving force of the electric motor 31 is controlled to be gradually decreased. As a result, the pressure applied to the head side chamber 35h by the booster piston 41 is gradually increased. That is, the control of the pressure applied to the molding material M from the plunger 21 by the action of the booster piston 41 is realized by controlling the driving force of the electric motor 31, not by controlling the supply and / or discharge of the hydraulic fluid (for example, flow rate control).

[0022] Thereafter, as indicated by the absence of arrow a4 (FIG. 4) in FIG. 5, the electric motor 31 is put into a state in which it does not generate driving force (for example, a torque-free state of a rotary electric motor). In other words, substantially only the force of the working fluid is applied to the booster piston 41. Pressure is maintained by maintaining this state.

[0023] As described above, in this embodiment, the force for moving the booster piston 41 forward is obtained by the difference between the force applied forward by the hydraulic fluid to the booster piston 41 and the force applied backward by the electric motor 31 to the booster piston 41. Therefore, for example, the force for driving the booster piston 41 forward can be obtained by a hydraulic drive unit, and the force can be controlled by an electric drive unit. The control of the electric drive unit generally has high responsiveness and small deviation compared to the control of a hydraulic drive unit (for example, control of the flow of the hydraulic fluid by a valve). Therefore, for example, the start timing of boosting can be controlled with high accuracy, and the pressure of the molding material M during boosting can be controlled with high accuracy. Also, during pressure retention, the electric motor 31 does not need to be driven. For example, it is only necessary to apply the pressure accumulated in the accumulator 47 to the rear chamber 35a. This makes it possible to reduce power consumption, for example.

[0024] <Specific examples of die casting machines> The configuration and operation of the die casting machine 1 described above can be applied to various die casting machines. In other words, the die casting machine 1 according to the embodiment may be embodied as appropriate. An example of the embodied die casting machine 1 will be described below.

[0025] (Overall configuration of die casting machine) Fig. 6 is a side view (partially including a cross-sectional view) showing the configuration of the main parts of the die casting machine 1. Fig. 7 is a top view showing the configuration of the main parts of the die casting machine 1. In each drawing, for the sake of convenience, various members are omitted from the illustration. Thus, for example, a component that is shown in Fig. 6 and would also be visible in Fig. 7 may be omitted from the illustration in Fig. 7. The same is true vice versa.

[0026] The molding material M (not shown here) is, for example, a metal such as aluminum. A metal in a molten state is sometimes called a molten metal. Note that instead of the molding material in a molten state, a molding material in a solid-liquid coexistence state (semi-solidified state or semi-molten state) may be injected into the cavity 107.

[0027] The mold 101 has, for example, a fixed mold 103 and a movable mold 105 facing the fixed mold 103. A cavity 107 into which a molding material is injected is formed between the fixed mold 103 and the movable mold 105. The fixed mold 103 is a mold that does not move. The movable mold 105 is a mold that moves in a direction facing the fixed mold 103 (mold opening / closing direction). The mold opening / closing direction is, for example, a horizontal direction.

[0028] The die casting machine 1 has a machine body 3 that performs mechanical operations, and a control device 5 that controls the machine body 3. The machine body 3 has, for example, a clamping device 7 that opens, closes, and clamps the die 101, an injection device 9 that injects molten metal into a cavity 107, and an extrusion device (not shown) that extrudes a product formed by solidifying the molten metal from the fixed die 103 or the movable die 105. The control device 5 may be regarded as a component of the injection device 9.

[0029] In the die casting machine 1, except for the configuration and operation of the injection device 9, the configuration and operation of other components (e.g., the mold clamping device 7 and the extrusion device) may have various configurations and operations, for example, may be publicly known configurations and operations. Therefore, the description of the configurations and operations of the other components will be omitted as appropriate. From another point of view, the operation of the injection device 9 is the control of the injection device 9 by the control device 5. Below, the configuration and operation of the mold clamping device 7 and the configuration of the control device 5 will be briefly described. After that, the configuration and operation of the injection device 9 will be described.

[0030] The mold clamping device 7 has, for example, a base 11, a fixed die plate 13 fixed on the base 11, a movable die plate 15 movable on the base 11 in the mold opening / closing direction, and a plurality of (for example, four) tie bars 17 inserted through these die plates. The fixed die plate 13 and the movable die plate 15 face each other in the mold opening / closing direction. The fixed die plate 13 holds a fixed die 103 on a surface facing the movable die plate 15. The movable die plate 15 holds a movable die 105 on a surface facing the fixed die plate 13. The mold 101 is opened and closed by the movement of the movable die plate 15 in the mold opening / closing direction. In addition, when the tie bars 17 are extended in a mold closed state, a mold clamping force according to the amount of extension is applied to the mold 101.

[0031] The control device 5 may be configured to include, for example, a computer, although not shown. The computer may be configured to include, for example, a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), and an external storage device, although not shown. The CPU executes a program stored in the ROM and / or the external storage device, thereby constructing various functional units that perform various calculations (including control). The control device 5 may also include a logic circuit that executes a certain operation, may include a power supply circuit, or may be conceptualized to include a driver. The control device 5 may be integrated in one location in terms of hardware, or may be distributed to multiple locations.

[0032] (injection device) The injection device 9 is located behind the fixed die plate 13 (on the opposite side to the movable die plate 15). The injection device 9 has the above-mentioned sleeve 19 and plunger 21, and a drive unit 23 that drives the plunger 21. Since the sleeve 19 and the plunger 21 can be regarded as consumables, only the drive unit 23 may be regarded as the injection device.

[0033] The sleeve 19 and the plunger 21 may have various configurations, for example, known configurations. In the illustrated example, they are as follows.

[0034] The sleeve 19 is provided so as to be inserted into the fixed die plate 13. The sleeve 19 does not have to be inserted into the fixed die 103 (example of FIG. 6) or may be inserted into the fixed die 103 (see FIG. 1). The sleeve 19 is a roughly cylindrical member and is disposed so as to extend in the horizontal direction (front-rear direction). A supply port 19a through which molten metal is supplied is opened on the upper surface of the sleeve 19.

[0035] The plunger 21 has a plunger tip 21a that slides on the sleeve 19, and a plunger rod 21b fixed to the plunger tip 21a. The plunger rod 21b extends in the front-rear direction, and the rear end of the plunger rod 21b is connected to the drive unit 23 by a coupling 25.

[0036] 6 and 7 show a state before the start of injection (see also FIG. 1). At this time, the plunger tip 21a is (at least partially) located in the sleeve 19 behind the supply port 19a. In this state, molten metal is poured into the supply port 19a by a water supply device (not shown) or the like. Next, the plunger tip 21a slides (moves forward) toward the cavity 107 by the driving force of the drive unit 23. As a result, the molten metal is injected into the cavity 107.

[0037] (Drive unit) 8 is a cross-sectional view showing a schematic configuration of a main part of the injection device 9. This figure shows the injection device 9 as seen from above. However, for convenience, components that cannot be seen from above (such as a second electric motor 31B described later) are also shown.

[0038] The injection device 9 (drive unit 23) has an injection cylinder 27 that is connected to the rear end of the plunger 21 by a coupling 25. A hydraulic fluid (e.g., oil) is supplied to the injection cylinder 27 from a hydraulic device 43 (see FIG. 9 described later). This enables the injection device 9 to apply a hydraulic driving force to the plunger 21.

[0039] The injection device 9 also has two first drive devices 29A each including a first electric motor 31A. The first drive devices 29A have an attachment / detachment section 33 that can be connected to and released from a piston rod 39 (described later) of the injection cylinder 27. This allows the injection device 9 to apply an electric driving force to the plunger 21.

[0040] Furthermore, the injection device 9 has a second drive device 29B including a second electric motor 31B. The second drive device 29B is connected to a booster piston 41 of the injection cylinder 27. The second electric motor 31B is an electric motor equivalent to the electric motor 31 described with reference to Figs. 1 to 5. Here, the electric motor 31 is called the second electric motor 31B in order to distinguish it from the first electric motor 31A.

[0041] The outline of the operation of the injection device 9 when injecting the molding material M into the mold 101 has been described with reference to Figures 1 to 5. As can be understood from the description of Figures 1 to 5, the operation from the start of injection to the completion of pressure dwell is realized by supplying hydraulic fluid to the injection cylinder 27 and driving the second electric motor 31B. The first electric motor 31A contributes to, for example, retracting the plunger 21 after the completion of pressure dwell.

[0042] (Injection cylinder) The injection cylinder 27 is disposed, for example, behind the plunger 21 and coaxially with the plunger 21. The injection cylinder 27 has, for example, a cylinder member 35, an injection piston 37 capable of sliding inside the cylinder member 35, a piston rod 39 extending forward (toward the plunger 21) from the injection piston 37, and a booster piston 41 capable of pressurizing the working fluid behind the injection piston 37.

[0043] The cylinder member 35 is, for example, a generally cylindrical member. The shape of the internal cross section of the cylinder member 35 is, for example, circular. The outer shape (outer shape) of the cylinder member 35 may be an appropriate shape such as a rectangular parallelepiped. The cylinder member 35 is immovable relative to the fixed die plate 13. The cylinder member 35 has a small diameter cylinder 35x and a large diameter cylinder 35y connected in series to the rear end of the small diameter cylinder 35x. The inner diameter of the large diameter cylinder 35y is larger than the inner diameter of the small diameter cylinder 35x.

[0044] The injection piston 37 is, for example, a generally cylindrical member. The diameter of the injection piston 37 is generally the same as the inner diameter of the small diameter cylinder 35x. A packing (not shown) may be interposed between the injection piston 37 and the small diameter cylinder 35x. Even when a packing is interposed, it is expressed that the injection piston 37 slides inside the small diameter cylinder 35x (cylinder member 35). The same applies to other members (e.g., booster piston 41). The internal space of the small diameter cylinder 35x is partitioned by the injection piston 37 into a rod side chamber 35r on the piston rod 39 side and a head side chamber 35h on the opposite side.

[0045] The piston rod 39 is, for example, a generally cylindrical member. The diameter of the piston rod 39 is smaller than the diameter of the injection piston 37. The difference therebetween may be set appropriately. The piston rod 39 extends to the outside of the cylinder member 35, and its front end is connected to the rear end of the plunger 21 by the coupling 25.

[0046] The piston rod 39 moves integrally with the plunger 21. Therefore, the injection cylinder 27 is configured to be able to move the piston rod 39 (injection piston 37) with a stroke equal to or greater than the stroke assumed for the plunger 21.

[0047] The booster piston 41 is, for example, a piston that can slide in the cylinder member 35. More specifically, the booster piston 41 has a small diameter piston 41a that slides in the small diameter cylinder 35x and a large diameter piston 41b that slides in the large diameter cylinder 35y. The large diameter piston 41b is connected in series to the rear end of the small diameter piston 41a. Note that, unlike the illustrated example, a connecting portion having a diameter smaller than the diameter of the small diameter piston 41a may be formed between the small diameter piston 41a and the large diameter piston 41b.

[0048] The inside of the cylinder member 35 (35x and 35y) behind the injection piston 37 is divided by the booster piston 41 into a head side chamber 35h on the injection piston 37 side and a rear side chamber 35a on the opposite side. The inside of the large diameter cylinder 35y is divided by the large diameter piston 41b into a front side chamber 35f on the small diameter cylinder 35x side and a rear side chamber 35a on the opposite side. The booster piston 41 has a first surface 41c (the tip end surface of the small diameter piston 41a) that receives pressure from the working fluid in the head side chamber 35h and a second surface 41d (the rear end surface of the small diameter piston 41a) that receives pressure from the working fluid in the rear side chamber 35a. The area of ​​the second surface 41d is larger than the area of ​​the first surface 41c.

[0049] As can be understood from the operation described with reference to Figures 1 to 5, the head side chamber 35h and the rear side chamber 35a are filled with hydraulic fluid. On the other hand, the rod side chamber 35r and the front side chamber 35f may or may not be filled with hydraulic fluid. For example, the rod side chamber 35r and the front side chamber 35f may be open to the atmosphere. When they are not filled with hydraulic fluid, the rod side chamber 35r and the front side chamber 35f may contain a small amount of hydraulic fluid (oil) for lubrication.

[0050] In the following description, an example is taken of a state in which the rod side chamber 35r is filled with hydraulic fluid. The hydraulic fluid in the rod side chamber 35r contributes to, for example, reducing the probability of the injection piston 37 moving forward at a rapid speed (jumping) at the start of injection and / or absorbing surge pressure at the completion of filling of the molten metal.

[0051] When the front chamber 35f is filled with hydraulic fluid, the hydraulic fluid may or may not be used for some purpose. An example of the former is a mode in which hydraulic fluid is supplied from the hydraulic device 43 to the front chamber 35f after completion of pressure maintenance to generate at least a part of the driving force for moving the booster piston 41 backward. Another example is a mode in which the hydraulic device 43 prohibits the hydraulic fluid from being discharged from the front chamber 35f at an appropriate time to prohibit unintended forward movement of the booster piston 41. An example of a mode in which the hydraulic fluid in the front chamber 35f is not used is a mode in which the front chamber 35f is simply connected to a tank.

[0052] (Frame) Any suitable method may be used to install the cylinder member 35 so that it cannot move relative to the fixed die plate 13. In the example shown in Fig. 6 and Fig. 7, the cylinder member 35 is connected to the fixed die plate 13 by a frame 45. As described later, the frame 45 also contributes to supporting the first driving device 29A and the like.

[0053] The frame 45 may have any shape. For example, as shown in Fig. 6, the frame 45 may have a first portion 45a located between the fixed die plate 13 and the cylinder member 35 to fix them together, and a second portion 45b connected to the first portion 45a and supporting the cylinder member 35 from below.

[0054] The shapes of the first portion 45a and the second portion 45b are also arbitrary. For example, the first portion 45a may have a portion located below the plunger 21 (FIG. 6, reference numerals omitted), a portion located to the side and / or above the plunger 21 (FIG. 7), and a plate 45c adjacent to the front end of the cylinder member 35 (FIGS. 6 and 7).

[0055] (Hydraulic device) FIG. 9 is a circuit diagram showing an example of a hydraulic device 43 that supplies hydraulic fluid to the injection cylinder 27 to drive the injection cylinder 27.

[0056] (Accumulators, pumps and tanks) The hydraulic device 43 has an accumulator 47 and a pump 49 as hydraulic pressure sources. The hydraulic device 43 also has a tank 51 that stores hydraulic fluid. For convenience, the tanks 51 are illustrated in multiple positions. In reality, the number of tanks 51 may be less than the number illustrated, for example, only one tank may be used.

[0057] The roles of the accumulator 47 and the pump 49 (and the tank 51) may be appropriately determined.

[0058] In this embodiment, as described with reference to Figs. 1 to 5, hydraulic fluid is supplied from the accumulator 47 to the head side chamber 35h, which causes the injection piston 37 to move forward to perform injection. In addition, hydraulic fluid is supplied from the accumulator 47 to the rear side chamber 35a, which causes the booster piston 41 to move forward to perform boosting. The accumulator 47 is filled by pushing the hydraulic fluid in the head side chamber 35h out into the accumulator 47 by retracting the injection piston 37 with the first drive device 29A, as will be described in detail later.

[0059] Part of the filling of the accumulator 47 may be performed by retracting the booster piston 41. For example, the booster piston 41 may be retracted by the second electric motor 31B to push the working fluid in the rear chamber 35a to the accumulator 47. And / or, in a part of a section in which the injection piston 37 is retracted by the first driving device 29A (for example, an initial section of retraction), the discharge of the working fluid from the head side chamber 35h may be prohibited to retract the booster piston 41 to push the working fluid in the rear chamber 35a to the accumulator 47.

[0060] However, unlike the description of this embodiment, the first driving device 29A may charge the accumulator 47 only with the hydraulic fluid discharged from the head side chamber 35h. For example, the booster piston 41 may be retracted as described above while the hydraulic fluid in the rear side chamber 35a is discharged to the tank 51. Also, unlike the description of this embodiment, the booster piston 41 may be retracted by supplying hydraulic fluid to the head side chamber 35h and / or the front side chamber 35f by the pump 49.

[0061] The pump 49 supplies hydraulic fluid to the rod side chamber 35r when, for example, the first drive device 29A retracts the injection piston 37. Furthermore, the pump 49 may supply hydraulic fluid to the front side chamber 35f when retracting the booster piston 41. Also, for example, the pump 49 contributes to replenishing hydraulic fluid in an amount equivalent to hydraulic fluid leaked from the injection cylinder 27, etc., and / or to supply hydraulic fluid during maintenance of the injection device 9.

[0062] A rearward driving force is applied to the injection piston 37 by the first driving device 29A. Therefore, in a mode in which hydraulic fluid is supplied from the pump 49 to the rod side chamber 35r, the force with which the hydraulic fluid in the rod side chamber 35r pushes the injection piston 37 rearward may be smaller than the force with which the hydraulic fluid in the head side chamber 35h pushes the injection piston 37 forward. In other words, the product of the pressure in the rod side chamber 35r and the area over which the pressure acts on the injection piston 37 may be smaller than the product of the pressure in the head side chamber 35h (the accumulator 47 from another perspective) and the area over which the pressure acts on the injection piston 37.

[0063] Specifically, for example, the force with which the hydraulic fluid in the rod side chamber 35r pushes the injection piston 37 rearward may be 2 / 3 or less, 1 / 2 or less, 1 / 5 or less, or 1 / 10 or less of the force with which the hydraulic fluid in the head side chamber 35h pushes the injection piston 37 forward (the pressure of the accumulator 47 may be based on the pressure when the injection piston 37 returns to the position before the start of injection. The same applies to the next paragraph.) Furthermore, the pressure in the rod side chamber 35r may be equivalent to the tank pressure (pressure of the tank 51) and / or atmospheric pressure, and may be slightly lower than these pressures.

[0064] The pressure in the rod side chamber 35r may be higher than the tank pressure and the atmospheric pressure. In this case, the pump 49 assists the first drive device 29A in retracting the plunger 21. At this time, the force with which the hydraulic fluid in the rod side chamber 35r pushes the ejection piston 37 rearward may be set appropriately. For example, the force with which the hydraulic fluid in the rod side chamber 35r pushes the ejection piston 37 rearward may be set to 1 / 10 or more, 1 / 5 or more, 1 / 2 or more, or 2 / 3 or more of the force with which the hydraulic fluid in the head side chamber 35h pushes the ejection piston 37 forward. The lower limit in the previous paragraph may be combined with the lower limit in this paragraph, unless a contradiction occurs.

[0065] Similarly to the above, in a mode in which the working fluid is supplied to the front side chamber 35f from the pump 49, the pressure in the front side chamber 35f does not need to be high. The above description of the pressure or force generated by the working fluid in the rod side chamber 35r may be applied to the pressure or force generated by the working fluid in the front side chamber 35f by replacing the rod side chamber 35r with the front side chamber 35f, replacing the head side chamber 35h with the rear side chamber 35a, and replacing the injection piston 37 with the booster piston 41.

[0066] As described above, in this embodiment, the pump 49 does not basically fill the accumulator 47. In addition, when the injection piston 37 (and the booster piston 41) retracts, the pressure in the rod side chamber 35r (and the front side chamber 35f) to which the hydraulic fluid is supplied from the pump 49 may be low. Therefore, for example, compared with a general hydraulic type or a known hybrid type injection device, the capacity of the pump 49 (the amount of hydraulic fluid delivered in one cycle) may be made smaller. In addition, the hydraulic fluid is directly supplied between the head side chamber 35h (and the rear side chamber 35a) and the accumulator 47, and the tank 51 is not interposed therebetween, so the volume of the tank 51 can also be reduced.

[0067] The accumulator 47 may be configured by an appropriate type of accumulator such as a weight type, a spring type, a gas pressure type (including an air pressure type), a cylinder type, a bladder type, etc. For example, the accumulator 47 is a gas pressure type, a cylinder type, or a bladder type accumulator, and pressure is accumulated by compressing a gas (e.g., air or nitrogen) held in the accumulator 47.

[0068] Pump 49 may be a rotary pump that discharges hydraulic fluid by the rotation of a rotor, or a plunger pump that discharges hydraulic fluid by the reciprocation of a piston. Pump 49 may be a fixed displacement pump in which the amount of discharge in one period of the movement of a rotor or piston is fixed, or a variable displacement pump in which the amount of discharge is variable. In addition, it is sufficient for pump 49 to be able to discharge hydraulic fluid in one direction, but it may also have the same structure as a bidirectional (two-way) pump.

[0069] Although not specifically shown, the pump 49 is driven by, for example, a rotary electric motor. This electric motor may be a DC motor or an AC motor, an induction motor or a synchronous motor. The electric motor may function as a constant speed motor provided in an open loop, or may function as a servo motor provided in a closed loop. The electric motor (pump 49) may be driven only when necessary, or may be driven constantly.

[0070] The tank 51 is, for example, an open tank. That is, the tank 51 holds the hydraulic fluid under atmospheric pressure. Therefore, for example, when the rod side chamber 35r is connected to the tank 51, the pressure of the rod side chamber 35r drops to atmospheric pressure or a pressure close to atmospheric pressure.

[0071] (Hydraulic circuit) The hydraulic device 43 has a hydraulic circuit 53 that controls the flow of hydraulic fluid among the injection cylinder 27, the accumulator 47, the pump 49, and the tank 51. There are various possible specific configurations for the hydraulic circuit 53 that realizes the division of roles between the accumulator 47 and the pump 49 as described above. The configuration of the hydraulic circuit 53 shown in Fig. 9 is merely one example.

[0072] The hydraulic circuit 53 illustrated in Fig. 9 will be described below in the following order. First, the flow path between the accumulator 47 and the head side chamber 35h will be described. Next, the flow path between the accumulator 47 and the rear side chamber 35a will be described. Next, the flow path between the rod side chamber 35r and the tank 51 will be described. Next, the flow path between the pump 49 and the rod side chamber 35r will be described. After that, other configurations of the hydraulic circuit 53 will be described.

[0073] (Flow passage between the accumulator and the head side chamber) The hydraulic circuit 53 has a flow path 54a that communicates between the accumulator 47 and the head side chamber 35h. The flow path 54a contributes to, for example, causing the hydraulic fluid to flow from the accumulator 47 to the head side chamber 35h, thereby moving the injection piston 37 forward. In addition, the flow path 54a contributes to, for example, causing the hydraulic fluid to flow from the head side chamber 35h to the accumulator 47, thereby filling the accumulator 47, when the injection piston 37 retracts.

[0074] The hydraulic circuit 53 has, for example, a flow control valve 55 and a check valve 59A as valves that are located in the flow passage 54a and can allow or prohibit the flow of hydraulic fluid in the flow passage 54a.

[0075] The flow control valve 55 can control the flow rate of the hydraulic fluid in the flow path 54a. By controlling the flow rate of the hydraulic fluid supplied from the accumulator 47 to the head side chamber 35h, for example, the forward speed of the injection piston 37 is controlled. In other words, the flow control valve 55 constitutes a so-called meter-in circuit.

[0076] The flow control valve 55 is, for example, a pressure compensated flow adjustment valve that can keep the flow rate constant even if there is a pressure fluctuation. The flow control valve 55 is, for example, used in a servo mechanism and is, for example, a servo valve that can modulate the flow rate steplessly (continuously to any value) in response to an input signal.

[0077] The flow control valve 55 may have various configurations, for example, a known configuration. In the illustrated example, the flow control valve 55 has a main valve 56 that controls the flow of the hydraulic fluid in the flow path 54a, and a pilot valve 57 that controls the operation of the main valve 56.

[0078] The main valve 56 is located in the flow path 54a and directly controls the flow rate of the hydraulic fluid in the flow path 54a. The main valve 56 is, for example, a two-port, two-position changeover valve in which the flow is continuously switched depending on the position of the valve disc. The position of the valve disc is controlled by pilot pressure introduced on both sides of the valve disc's moving direction. The position of the valve disc is also detected by a sensor (for example, a differential transformer).

[0079] The pilot valve 57 controls the pilot pressure introduced to both sides of the valve disc of the main valve 56. Specifically, the pilot valve 57 has two ports communicating with both sides (two flow paths 54b) of the valve disc of the main valve 56, and two ports communicating with the accumulator 47 (flow path 54c) and the tank 51 (flow path 54d). The pilot valve 57 is configured as a 4-port, 3-position changeover valve that continuously switches the connection between the former two ports and the latter two ports depending on the position of the valve disc. The position of the valve disc is controlled by, for example, an electromagnetic drive unit (for example, a solenoid).

[0080] In addition, in each of the main valve 56 and the pilot valve 57, leakage of hydraulic fluid is collected in the tank 51. The valve body may be biased to a predetermined position by a spring (the same applies to the valve bodies of the other valves).

[0081] The check valve 59A is configured as a check valve that is opened and closed by introduction of pilot pressure. When pilot pressure is not applied, the check valve 59A allows flow from the accumulator 47 to the head side chamber 35h and prohibits flow in the reverse direction. Therefore, for example, when the pressure booster piston 41 pressurizes the hydraulic fluid in the head side chamber 35h and the pressure in the head side chamber 35h becomes higher than the pressure in the accumulator 47, the check valve 59A closes automatically.

[0082] The introduction of pilot pressure to the check valve 59A may be performed, for example, by a switching valve 60A located between the check valve 59A and the accumulator 47. The switching valve 60A has, for example, two ports, a port for supplying an opening pilot pressure to the check valve 59A and a port for supplying a closing pilot pressure to the check valve 59A, and two ports leading to the accumulator 47 and the tank 51. The switching valve 60A is configured as a 4-port 2-position switching valve that switches the connection between the former two ports and the latter two ports depending on the position of the valve disc. The position of the valve disc is controlled, for example, by an electromagnetic drive unit (for example, a solenoid).

[0083] (Flow path between the accumulator and the rear chamber) The hydraulic circuit 53 has a flow path 54m that communicates the accumulator 47 and the rear chamber 35a. The flow path 54m contributes to, for example, flowing hydraulic fluid from the accumulator 47 to the rear chamber 35a to advance the booster piston 41. In addition, the flow path 54m contributes to filling the accumulator 47 by flowing hydraulic fluid from the rear chamber 35a to the accumulator 47 when the booster piston 41 retracts.

[0084] The flow path 54m shares a part with the flow path 54a on the side of the accumulator 47. However, the flow path 54m may be a flow path separate from the flow path 54a over its entirety.

[0085] The flow control valve 55 described above may be located in a portion shared by the flow paths 54m and 54a. That is, the flow control valve 55 may be capable of controlling the flow rate of the hydraulic fluid flowing from the accumulator 47 to the rear chamber 35a. However, the flow control valve 55 may be located in a portion of the flow path 54a that is not shared with the flow path 54m.

[0086] The hydraulic circuit 53 has, for example, a check valve 59E in addition to the flow control valve 55, which is a valve located in the flow path 54m and capable of allowing and prohibiting the flow of hydraulic fluid in the flow path 54m. The check valve 59E is configured, for example, as a check valve that is opened and closed by introduction of pilot pressure, similar to the check valve 59A. For example, when no pilot pressure is applied, the check valve 59E allows a flow from the accumulator 47 to the rear chamber 35a and prohibits a flow in the reverse direction. The configuration for introducing pilot pressure to the check valve 59E may be the same as the configuration of the check valve 59A, and is not shown in FIG. 9.

[0087] (Flow passage between the rod side chamber and the tank) The hydraulic circuit 53 has a flow path 54e that communicates between the rod side chamber 35r and the tank 51. The flow path 54e contributes to allowing the hydraulic fluid in the rod side chamber 35r to flow to the tank 51 when the injection piston 37 advances, for example, thereby allowing the injection piston 37 to advance.

[0088] The hydraulic circuit 53 has, for example, a check valve 59B, which is located in the flow path 54e and can allow and prohibit the flow of hydraulic fluid in the flow path 54e. The configuration of the check valve 59B is similar to that of the check valve 59A, for example. The above-mentioned explanation regarding the configuration of the check valve 59A may be applied to the configuration of the check valve 59B, unless a contradiction occurs. When pilot pressure is not applied, the check valve 59B allows the flow from the rod side chamber 35r to the tank 51 and prohibits the flow in the reverse direction.

[0089] The pilot pressure may be introduced to the check valve 59B by, for example, a switching valve 60B located between the check valve 59B and the accumulator 47. The configuration of the switching valve 60B is similar to that of the switching valve 60A. The above-mentioned explanation regarding the configuration of the switching valve 60A may be applied to the configuration of the switching valve 60B, unless a contradiction occurs.

[0090] An accumulator 61 may be connected between the rod side chamber 35r and the tank 51 (more specifically, for example, between the check valve 59B and the tank 51). This accumulator 61 contributes to absorbing surge pressure generated in the rod side chamber 35r when the filling of the molten metal is completed, for example. The above explanation regarding the configuration of the accumulator 47 may be applied to the configuration of the accumulator 61, unless a contradiction occurs. However, since the accumulator 61 is not used as a driving source, it may be smaller than the accumulator 47 and may have a lower accumulated pressure.

[0091] (Flow passage between the pump and the rod side chamber) The hydraulic circuit 53 has a flow path 54f that communicates the pump 49 and the rod side chamber 35r. The flow path 54f contributes to supplying the working fluid to the rod side chamber 35r by causing the working fluid to flow from the pump 49 to the rod side chamber 35r when the injection piston 37 is retracted by the first drive device 29A, for example.

[0092] The hydraulic circuit 53 has, for example, a switching valve 62 and a check valve 63A as valves that are located in the flow path 54f and can allow or prohibit the flow of hydraulic fluid in the flow path 54f. As will be understood from the following explanation, the combination of these two valves may be regarded as one valve.

[0093] The switching valve 62 is located in the flow path 54h that supplies the working fluid from the pump 49 to the head side chamber 35h, and also functions as a valve that allows or prohibits the flow of the working fluid in the flow path 54h. As described above, the supply of the working fluid from the pump 49 to the head side chamber 35h is for, for example, compensation for leaked working fluid and / or maintenance.

[0094] The switching valve 62 has two ports, one leading to the rod side chamber 35r and one leading to the head side chamber 35h, and two ports leading to the pump 49 and the tank 51. The switching valve 62 is configured as a 4-port 3-position switching valve that switches the connection between the former two ports and the latter two ports depending on the position of the valve disc. The position of the valve disc is controlled, for example, by an electromagnetic drive unit (for example, a solenoid).

[0095] More specifically, the three positions of the switching valve 62 are as follows. In the left position of the figure, the rod side chamber 35r is connected to the pump 49, and the head side chamber 35h is connected to the tank 51. In the right position of the figure, the rod side chamber 35r is connected to the tank 51, and the head side chamber 35h is connected to the pump 49. In the center position of the figure, none of the ports are connected. Therefore, for example, by placing the switching valve 62 in the position on the left side of the drawing, it is possible to supply hydraulic fluid from the pump 49 to the rod side chamber 35r.

[0096] The check valve 63A is located between the rod side chamber 35r and the switching valve 62. The check valve 63A allows flow from the switching valve 62 to the rod side chamber 35r and prohibits flow in the opposite direction. As a result, for example, when the switching valve 62 is positioned to the right in the figure in order to supply working fluid from the pump 49 to the head side chamber 35h, the working fluid in the rod side chamber 35r is prohibited from flowing to the tank 51 via the switching valve 62.

[0097] Although not shown, a switching valve may not be shared between the flow paths 54f and 54h. For example, each flow path may be provided with a three-port, three-position switching valve that allows and prohibits the flow of hydraulic fluid, or a pilot-type check valve.

[0098] (Other configurations of hydraulic circuits) As described above, the hydraulic circuit 53 has a flow path 54h for supplying hydraulic fluid from the pump 49 to the head side chamber 35h. The hydraulic circuit 53 has, for example, the above-described switching valve 62 and check valve 64 as valves located in the flow path 54h and capable of allowing and prohibiting the flow of hydraulic fluid in the flow path 54h.

[0099] The check valve 64 is located between the head side chamber 35h and the switching valve 62. The check valve 64 allows flow from the switching valve 62 to the head side chamber 35h and prohibits flow in the opposite direction. As a result, for example, when the switching valve 62 is positioned on the left side in the figure to supply hydraulic fluid from the pump 49 to the rod side chamber 35r, hydraulic fluid in the head side chamber 35h is prohibited from flowing to the tank 51 via the switching valve 62. In the example shown in the figure, the check valve 64 is a pilot-type check valve that is closed (prohibits bidirectional flow) by the introduction of pilot pressure.

[0100] The pilot pressure of the check valve 64 may be introduced by, for example, a shuttle valve 65. The shuttle valve 65 has two inlets and one outlet. One of the two inlets is connected to the head side chamber 35h side of the flow path 54h relative to the check valve 64. The other of the two inlets is connected to the accumulator 47 via a switching valve 66, which will be described later. The outlet is connected to the check valve 64. The outlet is connected to the higher pressure side of the two inlets, and applies the pressure from the connected inlet to the check valve 64 as the pilot pressure. This reduces, for example, the probability that the check valve 64 is opened at a time when it is not intended to be opened.

[0101] The flow of hydraulic fluid from the accumulator 47 to the shuttle valve 65 may be controlled, for example, by a switching valve 66 located between them. The switching valve 66 has, for example, three ports: a port connected to the shuttle valve 65, a port connected to the accumulator 47, and a port connected to the tank 51. Depending on the position of the valve disc, the switching valve 66 connects the port leading to the shuttle valve 65 to one of the other two ports. The position of the valve disc is controlled, for example, by an electromagnetic drive unit (for example, a solenoid).

[0102] The hydraulic circuit 53 has, for example, a flow path 54k for supplying hydraulic fluid from the pump 49 to the accumulator 47. As described above, the accumulator 47 is basically filled by retracting the injection piston 37 by the first drive device 29A and pushing out the hydraulic fluid in the head side chamber 35h to the accumulator 47. The supply of hydraulic fluid from the pump 49 to the accumulator 47 is, for example, for compensation for leaked hydraulic fluid and / or for maintenance.

[0103] The hydraulic circuit 53 has, for example, a switching valve 46, which is located in the flow path 54k and can permit or prohibit the flow of hydraulic fluid in the flow path 54k. The switching valve 46 connects the accumulator 47 to the pump 49 or the tank 51, or cuts off both connections, depending on the position of the valve disc, for example. The position of the valve disc is controlled, for example, by sequentially operating an electromagnetic drive unit and a pilot drive unit (see the operation method of the flow control valve 55). The pilot pressure may be, for example, the pressure from the accumulator 47.

[0104] In a mode in which the front chamber 35f is filled with hydraulic fluid, the hydraulic circuit 53 may have a flow path (not shown) connecting the front chamber 35f and the tank 51 (and the pump 49, if necessary). A valve that allows and prohibits the flow of hydraulic fluid may be provided in the flow path.

[0105] The hydraulic circuit 53 may have check valves 63B, 63C, and 63D at an appropriate position that allow the hydraulic fluid to flow from the pump 49 and prohibit the flow in the opposite direction. The hydraulic circuit 53 may also have a check valve (reference number omitted) that allows the hydraulic fluid to flow from the switching valve 66 to the tank 51 and prohibits the flow in the opposite direction. The hydraulic circuit may also have a cock 58 at an appropriate position. The cock 58 is for maintenance, for example, and is closed when injection is being performed. To the end of the flow path extending from the cock 58, for example, various instruments (reference numbers omitted) such as a pressure gauge may be connected. The hydraulic circuit 53 may also have a filter 48 and a relief valve 52 at an appropriate position.

[0106] (First drive unit) 8 has the first electric motor 31A and the attachment / detachment part 33 that can be connected to and released from the piston rod 39, as described above. The first drive device 29A has, for example, a first transmission mechanism 67A, a first conversion mechanism 68A, and a movable member 69 in this order from the first electric motor 31A to the attachment / detachment part 33 as components for transmitting the driving force of the first electric motor 31A to the piston rod 39.

[0107] The first motor 31A is a rotary motor. Although not shown in particular, the first motor 31A has a stator constituting one of the armature or the field magnet, and a rotor constituting the other of the armature or the field magnet, as is well known. The rotor rotates around an axis relative to the stator. The specific configuration of the first motor 31A may be any appropriate one. For example, the first motor 31A may be a DC motor or an AC motor, an induction motor or a synchronous motor, and may or may not have a brake. The first motor 31A is configured as, for example, a servo motor, and configures a servo mechanism together with a sensor (not shown) that detects the rotation of the first motor 31A and a servo driver (not shown) that supplies power to the first motor 31A.

[0108] The main body (stator) of the first electric motor 31A is fixed to a stationary part (e.g., the cylinder member 35) of the injection device 9, and various parallel and rotational movements are restricted. The position and orientation of the first electric motor 31A may be set as appropriate. In the illustrated example, the first electric motor 31A is disposed to the side of the injection cylinder 27 and fixed to the rear surface of the plate 45c of the frame 45. The first electric motor 31A is disposed such that its output shaft is parallel to the injection cylinder 27 and faces forward.

[0109] The first transmission mechanism 67A transmits the rotation of the first electric motor 31A, and contributes to, for example, improving the degree of freedom of arrangement of the first electric motor 31A and / or changing the speed of the rotation. The first transmission mechanism 67A is, for example, configured by a pulley-belt mechanism, and has a first pulley 70A fixed to the output shaft of the first electric motor 31A, a first nut 71A (pulley) also used for the first conversion mechanism 68A, and a first belt 72A hung on the first pulley 70A and the first nut 71A. Therefore, when the first electric motor 31A rotates, the rotation is transmitted to the first conversion mechanism 68A via the first transmission mechanism 67A. The diameter of the first pulley 70A and the diameter of the first nut 71A may be larger than each other, or may be equal to each other. In the illustrated example, the diameter of the first nut 71A is larger than the diameter of the first pulley 70A, and the rotation of the first electric motor 31A is decelerated.

[0110] The specific location of the first transmission mechanism 67A may be set appropriately. In the illustrated example, the first transmission mechanism 67A is located to the side of the injection cylinder 27, and is disposed within the plate 45c of the frame 45. The first pulley 70A and the first nut 71A are aligned in the lateral direction of the injection cylinder 27.

[0111] The first conversion mechanism 68A contributes to converting the rotational motion of the first electric motor 31A into linear motion (translational motion). The first conversion mechanism 68A is configured, for example, by a screw mechanism (for example, a ball screw mechanism or a sliding screw mechanism). The first conversion mechanism 68A has a first screw shaft 73A and a first nut 71A that is screwed to the first screw shaft 73A directly or via a ball (not shown). One of the members of the first screw shaft 73A and the first nut 71A (the first nut 71A in the illustrated example) is, for example, allowed to rotate about its axis and is restricted from moving in the axial direction. The other member (the first screw shaft 73A in the illustrated example) is, for example, restricted from rotating about its axis and is allowed to move in the axial direction. Therefore, when one member (the first nut 71A) is rotated, the other member (the first screw shaft 73A) is driven in the axial direction. The specific configuration of the first conversion mechanism 68A may be set as appropriate. For example, the screw groove may be one thread, or two or more threads. Furthermore, for example, the diameter, lead, etc. of the first screw shaft 73A are optional.

[0112] The first conversion mechanism 68A is arranged in parallel to the injection cylinder 27. That is, the first screw shaft 73A is parallel to the piston rod 39, and the direction of the linear motion of the first conversion mechanism 68A is parallel to the driving direction (front-rear direction) of the injection cylinder 27. The specific arrangement position of the first conversion mechanism 68A, the method of restricting the parallel movement of the first nut 71A, and the method of restricting the rotation of the first screw shaft 73A may be set appropriately. In the illustrated example, the first conversion mechanism 68A is located on the side of the injection cylinder 27 and is located closer to the injection cylinder 27 than the first electric motor 31A. The first nut 71A is arranged inside the plate 45c of the frame 45, and is supported by the plate 45c by a bearing (not shown) in a state where only rotation is permitted. The first screw shaft 73A is coupled to a movable member 69 that is only allowed to move parallel to the front-rear direction, so that its rotation is restricted.

[0113] The movable member 69 is a member driven in the front-rear direction by the driving force of the first electric motor 31A, and contributes to transmitting the driving force of the first electric motor 31A to the plunger 21 and also contributes to supporting the detachable part 33. The movable member 69 may be regarded as a part of the detachable part 33. The shape, dimensions and material of the movable member 69 are arbitrary. In the illustrated example, the movable member 69 is a member shared by the two first driving devices 29A (see also FIG. 7), extends in the lateral direction of the injection cylinder 27 (the vertical direction in FIG. 8), and has a shape having a hole through which the piston rod 39 is inserted. The movable member 69 is also generally in the shape of a plate facing in the front-rear direction.

[0114] The first driving device 29A may have a guide mechanism for guiding the movable member 69 in the front-rear direction (or, from another point of view, for restricting motion other than translation in the front-rear direction). In the example of Figs. 7 and 8, a pair of guide shafts 74 is illustrated as an example of the guide mechanism. The pair of guide shafts 74 extend in the front-rear direction and are fixed to the frame 45. The movable member 69 is allowed to move only in the front-rear direction by having the pair of guide shafts 74 inserted therethrough. Also, Fig. 6 illustrates a linear guide 75 that supports and guides the movable member 69 from below.

[0115] 8 is supported by the movable member 69 and moves in the front-rear direction together with the movable member 69. The detachable part 33 connects and disconnects the movable member 69 to and from a predetermined portion of the piston rod 39 (detachable part 39z). The detachable part 39z is located outside the cylinder member 35, regardless of the position of the injection piston 37, for example. That is, even when the injection piston 37 is located at the rearmost position by abutting a stopper (not shown) in the cylinder member 35 at its rear, the detachable part 39z is located outside the cylinder member 35.

[0116] By connecting the movable member 69 to the detachable portion 39z, for example, the plunger 21 can be moved backward by the driving force of the first electric motor 31A. Also, by releasing the connection between the movable member 69 and the piston rod 39, for example, when the working fluid is supplied to the head side chamber 35h to move the plunger 21 forward at high speed, a decrease in speed of the plunger 21 caused by the inertial force of the first drive device 29A can be avoided.

[0117] The detachable portion 33 has, for example, an engaging member 76 that can engage with the detachable portion 39z of the piston rod 39, and an actuator 77 that drives the engaging member 76. The engaging member 76 is supported by the movable member 69 so as to be movable between an engaging position where the engaging member 76 engages with the detachable portion 39z in the front-rear direction, and a releasing position (position in FIG. 8) where the engagement is released. The actuator 77 moves the engaging member 76 between the engaging position and the releasing position.

[0118] The specific shapes of the engaging member 76 and the detachable portion 39z may be set appropriately. In the illustrated example, the detachable portion 39z has a small diameter portion 39a, a first large diameter portion 39b, and a second large diameter portion 39c. The first large diameter portion 39b is located behind the small diameter portion 39a and has a larger diameter than the small diameter portion 39a. The second large diameter portion 39c is located in front of the small diameter portion 39a and has a larger diameter than the small diameter portion 39a. The engaging member 76 is inserted between the first large diameter portion 39b and the second large diameter portion 39c, thereby engaging with them rearward or forward. The engaging member 76 is released from engagement by retreating from between the first large diameter portion 39b and the second large diameter portion 39c.

[0119] In the illustrated example, the diameters of the first large diameter portion 39b and the second large diameter portion 39c are the same as the diameter of most of the piston rod 39. That is, the small diameter portion 39a is formed by reducing the diameter of a portion of the piston rod 39. However, for example, the diameter of the small diameter portion 39a may be the same as the diameter of most of the piston rod 39. The first large diameter portion 39b and the second large diameter portion 39c may be formed by flanges. The first large diameter portion 39b and the second large diameter portion 39c may have different diameters from each other, unlike the illustrated example.

[0120] Although not shown, the engaging member 76 may have a recess on the small diameter portion 39a side when viewed in the axial direction of the piston rod 39. The recess accommodates at least a part of the small diameter portion 39a when the engaging member 76 moves to the engaging position, for example. By providing such a recess, for example, the degree of mutual engagement between the engaging member 76 and the first large diameter portion 39b (second large diameter portion 39c) can be increased with respect to the angular range around the axis of the small diameter portion 39a. The specific shape and dimensions of the recess may be set appropriately. For example, the recess formed in one engaging member 76 is semicircular in which the small diameter portion 39a is generally fitted. The two engaging members 76 engage with the first large diameter portion 39b over the entire circumference around the small diameter portion 39a.

[0121] The actuator 77 may have any suitable configuration. In the illustrated example, the actuator 77 is a combination of a spring and an air cylinder, although no particular reference number is given to it. Specifically, the actuator 77 has a cylinder chamber formed in the movable member 69, a piston that can slide in the cylinder chamber, and a piston rod that extends from the piston and is connected to the engaging member 76. The spring biases the piston, for example, in a direction in which the engaging member 76 is released from the engaging position. By supplying gas (for example, air) to the piston on the side opposite to the piston rod, the engaging member 76 moves from the released position to the engaged position. Other examples of the actuator 77 include, for example, a linear motor or a hydraulic cylinder.

[0122] The arrangement position of the first drive unit 29A may be set appropriately. In the illustrated example, the two first drive units 29A are arranged line-symmetrically with respect to the injection cylinder 27 in a top view. The two first drive units 29A are located, for example, at the same height as the injection cylinder 27 in the vertical direction. More specifically, for example, the axial centers of the two first screw shafts 73A and the piston rod 39 may be located at the same height in the vertical direction.

[0123] As described above, the first driving device 29A retracts the plunger 21 after the completion of injection. Therefore, the first driving device 29A is configured to be able to move the attachment / detachment part 33 with a stroke equal to or greater than the stroke intended for the plunger 21. Note that the stroke of the first driving device 29A and the stroke of the injection cylinder 27 may be equal to each other, or one may be greater than the other.

[0124] (Second driving device) As described above, the second drive device 29B includes the second electric motor 31B and drives the booster piston 41. The second drive device 29B has, as components for transmitting the driving force of the second electric motor 31B to the booster piston 41, for example, a second transmission mechanism 67B and a second conversion mechanism 68B in this order from the second electric motor 31B to the booster piston 41.

[0125] The second motor 31B is a rotary motor, similar to the first motor 31A. The above explanation regarding the configuration of the first motor 31A may be applied to the configuration of the second motor 31B, unless a contradiction occurs. The second motor 31B may be of the same type (e.g., AC or DC, and / or induction or synchronous) as the first motor 31A, or may be of a different type. In addition, the second motor 31B may have a different performance (e.g., rated torque) from the first motor 31A according to the difference in the roles of the first drive device 29A and the second drive device 29B.

[0126] The main body (stator) of the second electric motor 31B is fixed to a stationary part (e.g., the cylinder member 35) of the injection device 9, and various parallel and rotational movements are restricted. The position and orientation of the second electric motor 31B may be set appropriately. In the example of FIG. 6, the second electric motor 31B is disposed behind and below the injection cylinder 27. Also, in the example of FIG. 8, the second electric motor 31B is disposed so that the output shaft is parallel to the injection cylinder 27 and faces backward.

[0127] The second transmission mechanism 67B transmits the rotation of the second electric motor 31B in the same manner as the first transmission mechanism 67A which transmits the rotation of the first electric motor 31A. The above-mentioned explanation regarding the configuration of the first transmission mechanism 67A may be applied to the configuration of the second transmission mechanism 67B as long as no contradiction occurs. When applying, the term "first pulley 70A" is replaced with the term "second pulley 70B", the term "first nut 71A" is replaced with the term "second nut 71B", and the term "first belt 72A" is replaced with the term "second belt 72B". The second transmission mechanism 67B may have a different gear ratio and the like from the first transmission mechanism 67A according to the difference in the roles of the first drive device 29A and the second drive device 29B.

[0128] The specific location of the second transmission mechanism 67B may be set appropriately. In the illustrated example, the second transmission mechanism 67B is located behind the injection cylinder 27. The second nut 71B is coaxially arranged on the injection cylinder 27. The second pulley 70B is located below the second nut 71B (see the position of the second electric motor 31B in FIG. 6).

[0129] The second conversion mechanism 68B converts the rotational motion of the second electric motor 31B into linear motion, similar to the first conversion mechanism 68A that converts the rotational motion of the first electric motor 31A into linear motion. The above-mentioned explanation of the configuration of the first conversion mechanism 68A may be used for the configuration of the second conversion mechanism 68B, unless a contradiction occurs. When using, the term "first nut 71A" is replaced with the term "second nut 71B" and the term "first screw shaft 73A" is replaced with the term "second screw shaft 73B". Depending on the difference in the roles of the first driving device 29A and the second driving device 29B, the first conversion mechanism 68A and the second conversion mechanism 68B may have different specific configurations. For example, the two may differ in type (for example, whether it is a ball screw mechanism or a sliding screw mechanism), diameter and / or lead. In the illustrated example, the length of the second screw shaft 73B is shorter than the length of the first screw shaft 73A.

[0130] The second conversion mechanism 68B is disposed, for example, coaxially with the injection cylinder 27. The second threaded shaft 73B is connected to the booster piston 41 and its rotation is restricted. The second nut 71B is permitted to rotate about its axis, but other movements are restricted. Therefore, when the second nut 71B is rotated by the second electric motor 31B, the second threaded shaft 73B moves in the axial direction, and thus the booster piston 41 moves in the front-rear direction.

[0131] The method of restricting the translational movement of the second nut 71B and the method of restricting the rotation of the second screw shaft 73B may be any appropriate method. For example, the second nut 71B may be supported via a bearing on an appropriate member connected to the cylinder member 35, thereby allowing rotation while restricting other movements. Also, for example, the second screw shaft 73B may be restricted from rotating about its axis while allowing axial movement by a spline groove.

[0132] (Other configurations of die casting machines) The die casting machine 1 may have various sensors that detect various physical quantities related to the operation of the machine body 3. The control device 5 may control the hydraulic device 43, the first electric motor 31A, the second electric motor 31B, and the attachment / detachment unit 33 (actuator 77) based on the detected values ​​of the various sensors.

[0133] Examples of the above-mentioned sensors include a position sensor 99 (FIG. 8) for detecting the position of the piston rod 39 (plunger 21), a pressure sensor (not shown) for detecting the pressure of the accumulator 47, a pressure sensor 97H (FIG. 9) for detecting the pressure of the head side chamber 35h, a pressure sensor 97R (FIG. 9) for detecting the pressure of the rod side chamber 35r, a sensor (not shown) for detecting the position of the movable member 69, a sensor (not shown) for detecting the number of revolutions (rotational speed) of the first electric motor 31A, a sensor (not shown) for detecting the position of the booster piston 41, a sensor (not shown) for detecting the number of revolutions of the second electric motor 31B, a sensor (not shown) for detecting the torque of the first electric motor 31A, and / or a sensor (not shown) for detecting the torque of the second electric motor 31B.

[0134] Since the speed (or rotation speed) can be obtained by differentiating the position (or rotation position), the position sensor may be regarded as a speed sensor. Similarly, a sensor that detects the rotation speed may be regarded as a sensor that detects the rotation position. The various sensors may be configured in various ways, for example, as known configurations. For example, the sensors that detect the positions of the piston rod 39, the movable member 69, and the booster piston 41 may be linear encoders or laser length measuring devices. The sensors that detect rotation may be encoders or resolvers. The sensors that detect torque may use strain gauges. In addition, a current detector that detects the current flowing through the electric motor may also be regarded as a torque sensor.

[0135] (Operation of the injection unit) FIG. 10 is a diagram illustrating the operation of the injection device 9.

[0136] In Fig. 10, the horizontal axis represents time t. The solid line Lv represents the change in injection speed (the speed of the plunger 21), and the dashed line Lp represents the change in injection pressure (e.g., the pressure applied to the molten metal by the plunger 21). In the graph with the solid line Lv and the dashed line Lp, the vertical axis represents the magnitude of the injection speed V and the injection pressure P.

[0137] In the lower part of FIG. 10, the operations of the accumulator 47 (abbreviated as "ACC"), the first electric motor 31A, the second electric motor 31B, and the attachment / detachment unit 33 are shown.

[0138] In "ACC", "RELEASE 1" indicates a state in which hydraulic fluid is released from the accumulator 47 (mainly) to the head side chamber 35h. "RELEASE 2" indicates a state in which hydraulic fluid is released from the accumulator 47 (mainly) to the rear side chamber 35a. "FILL" indicates a state in which hydraulic fluid in the head side chamber 35h or the rear side chamber 35a is filled into the accumulator 47. "STOP" indicates a state in which any of the above flows of hydraulic fluid are prohibited.

[0139] In the "first electric motor" and "second electric motor," "forward rotation" indicates a state in which the attachment / detachment unit 33 or the booster piston 41 rotates in the forward direction. "Reverse rotation" indicates a state in which the attachment / detachment unit 33 or the booster piston 41 rotates in the opposite direction. "Stopped" indicates a state in which the attachment / detachment unit 33 or the booster piston 41 rotates in the opposite direction. Note that the stop of the electric motor may be, for example, any of the following states, unless otherwise specified: a torque-free state, a state in which position control is being performed, or a state in which the brake is applied.

[0140] In the "detachment", "ON" indicates a state in which the detachable part 33 is connected to the piston rod 39. "OFF" indicates a state in which the connection is released.

[0141] In "ACC", "First motor", "Second motor" and "Attachment / detachment", the dashed lines indicate the operation of a modified example which will be described later. Please refer to the solid lines here.

[0142] For example, in general, the injection device 9 sequentially performs low-speed injection (times t0 to t1), high-speed injection (times t1 to t3), pressure boosting (times t4 to t6), and pressure holding (times t6 to t7). That is, in the initial stage of injection, the injection device 9 performs injection at a relatively low speed (speed V L Next, the injection device 9 is operated at a relatively high speed (speed V H Next, the injection device 9 applies a force in the forward direction of the plunger 21 to the molten metal in the cavity 107 at a casting pressure P E After that, the injection unit 9 increases the pressure to the casting pressure P E Maintain pressure to maintain pressure.

[0143] The low-speed injection and the high-speed injection are performed by supplying the hydraulic fluid from the accumulator 47 to the head side chamber 35h (see "Release 1" of ACC in the figure). The pressure increase is performed, in the initial stage, by supplying the hydraulic fluid from the accumulator 47 to the head side chamber 35h. These operations correspond to, for example, Figures 1 to 3. The remaining steps of pressure increase and pressure maintenance are performed by supplying (applying pressure to) the hydraulic fluid from the accumulator 47 to the rear side chamber 35a (see "Release 2" of ACC in the figure). These operations correspond to Figures 4 and 5. Specifically, they are as follows.

[0144] (Low speed injection: t0~t1) Immediately before the start of low-speed injection, the injection device 9 is in the state shown in Fig. 1 and Fig. 6 to Fig. 9. That is, the injection piston 37 and the booster piston 41 are in the initial position such as the rear limit. The detachable part 33 is released from the connection (engagement). For example, various valves of the hydraulic circuit 53 are basically controlled so as to prohibit the flow of the working fluid. The first electric motor 31A, the second electric motor 31B, and the pump 49 (the electric motor driving the pump 49) are stopped. As described above, the electric motors may be stopped in an appropriate state. For example, at least one of these electric motors (for example, the second electric motor 31B) may be in a torque-free state from the viewpoint of reducing power consumption.

[0145] The control device 5 determines whether or not a predetermined injection start condition is satisfied. The injection start condition may be, for example, that information indicating that clamping of the fixed die 103 and the movable die 105 has been completed and that molten metal has been supplied to the sleeve 19 has been obtained. Then, when the control device 5 determines that the injection start condition is satisfied, it starts injection (low speed injection).

[0146] Specifically, the control device 5 opens the flow control valve 55 and the check valve 59A. This allows the hydraulic fluid to be supplied from the accumulator 47 to the head side chamber 35h. The control device 5 also opens the check valve 59B. This allows the hydraulic fluid to be discharged from the rod side chamber 35r. The injection piston 37 then advances while discharging the hydraulic fluid from the rod side chamber 35r due to the pressure it receives from the head side chamber 35h. As a result, the piston rod 39 and the plunger 21 advance.

[0147] The speed of the plunger 21 is controlled by adjusting the flow rate of the hydraulic fluid supplied to the head side chamber 35h by the flow rate control valve 55. Specifically, the control device 5 feedback controls the opening of the flow rate control valve 55 so that the speed of the plunger 21 detected by the position sensor 99 converges to a target speed. This feedback control may be, for example, feedback control of the speed itself, or feedback control of the substantial speed realized by feedback control of the position performed so that the detected position of the plunger 21 becomes the target position from moment to moment. The speed of the plunger 21 is, for example, low (for example, less than 1 m / s) and constant. However, the speed of the plunger 21 may be controlled in multiple stages.

[0148] When low-speed injection is being performed, the control device 5 releases the connection of the detachable part 33 to the piston rod 39. Therefore, the speed of the piston rod 39 is not affected by the driving state of the first electric motor 31A. In the illustrated example, the first electric motor 31A is stopped at the start of injection. Therefore, the piston rod 39 (detachable part 39z) advances, leaving behind the detachable part 33 (movable member 69).

[0149] (Advancement of the detachable part) The control device 5 starts the forward rotation of the first electric motor 31A at an appropriate time, and advances the detachable part 33. The start time of this forward rotation and the forward rotation speed may be set appropriately. However, in the illustrated example, the start time of the forward rotation and the forward rotation speed are set so that the detachable part 33 reaches a position (small diameter part 39a) at which it can be coupled to the plunger 21 by the time when it becomes necessary to engage the detachable part 33 with the plunger 21 (time t11 in the illustrated example).

[0150] Examples of the start time of the forward rotation of the first motor 31A and the forward rotation speed are given below. The start time of the forward rotation may be before the start of injection (before time t0), at the start of injection (time t0), during low-speed injection (illustrated example), during high-speed injection, or after high-speed injection. In addition, the speed of the attachment / detachment unit 33 driven by the forward rotation of the first motor 31A is a high-speed injection speed V H Also, the speed is lower than the low injection speed VL It may be lower than, equal to, or higher than.

[0151] As can be seen from the various examples of the start timing and speed described above, unlike the above explanation, the detachable portion 33 may temporarily or always precede the detachable portion 39z of the piston rod 39.

[0152] (High speed injection: t1~t3) When a predetermined high-speed start condition is satisfied, the control device 5 increases the opening of the flow control valve 55, increases the flow rate of the hydraulic fluid from the accumulator 47 to the head side chamber 35h, and increases the speed of the plunger 21. The control at this time may be the same as the control at the time of low-speed injection, except that the target speed is different. The high-speed start condition may be, for example, that the position of the plunger 21 has reached a predetermined high-speed switching position. The control device 5 may, for example, determine whether the detected position of the plunger 21 has reached the high-speed switching position and switch the target speed, or may simply realize the target position at each moment that is set based on the high-speed switching position and the target speed.

[0153] (Deceleration injection: t3~t4) When the cavity 107 is filled with a certain amount of molten metal, the plunger 21 is decelerated by the reaction force from the filled molten metal, while the injection pressure rises rapidly. The operation of each part is the same as that during high-speed injection. However, deceleration control may be performed to reduce the opening of the flow control valve 55. Such deceleration control, for example, can mitigate the impact during filling.

[0154] (Pressure increase by supplying hydraulic fluid to the head side chamber: t4~t5) The control device 5 controls the hydraulic circuit 53 to start boosting when a predetermined boosting start condition is satisfied. The boosting start condition is, for example, that the injection pressure based on the detection value of the pressure sensor 97H that detects the pressure of the head side chamber 35h (and the pressure sensor 97R that detects the pressure of the rod side chamber 35r as necessary) has reached a predetermined pressure, or that the detection position of the plunger 21 detected by the position sensor 99 has reached a predetermined position.

[0155] From low speed injection to decelerated injection, the control device 5 performs speed control based on the detection value (detection value of injection speed) of the position sensor 99. On the other hand, when pressure increase starts, the control device 5 performs pressure control based on the detection value (detection value of injection pressure) of the pressure sensor 97H (and pressure sensor 97R as necessary). In pressure control, the control device 5 feedback controls the flow control valve 55 so that the detection value of the injection pressure increases along a predetermined pressure increase curve, for example.

[0156] (Preparation for boosting with boost piston: before t5) The control device 5 controls the hydraulic circuit 53 and the second electric motor 31B to perform the operation described with reference to Fig. 3 at an appropriate time. That is, the control device 5 prepares for pressure boosting by the booster piston 41 (Fig. 4).

[0157] Specifically, the control device 5 opens the check valve 59E to allow the flow of hydraulic fluid from the accumulator 47 to the rear chamber 35a. As a result, the booster piston 41 receives a rearward pressure from the hydraulic fluid in the head chamber 35h and a forward pressure from the hydraulic fluid in the rear chamber 35a. Both pressures are from the accumulator 47 and are theoretically the same. On the other hand, the pressure-receiving area of ​​the booster piston 41 in the rear chamber 35a is larger than that in the head chamber 35h. Therefore, the force that the booster piston 41 receives from the hydraulic fluid is a forward force overall.

[0158] Meanwhile, the control device 5 controls the second electric motor 31B to apply a rearward driving force to the booster piston 41. The magnitude of the rearward force applied by the second electric motor 31B to the booster piston 41 is set to be equal to or greater than the magnitude of the forward force applied by the working fluid in the head side chamber 35h and the rear side chamber 35a to the booster piston 41. As a result, the booster piston 41 is maintained in a stopped state at the rear limit.

[0159] The second electric motor 31B is supplied with power so as to generate a driving force in a rotational direction that moves the booster piston 41 backward. However, the second electric motor 31B does not rotate in the above rotational direction (reverse rotation), but is stopped (FIG. 3) or rotates forward (FIG. 4). Therefore, in FIG. 10, "reverse rotation" indicating the operation of the second electric motor 31B around time t5 is written in parentheses.

[0160] From the viewpoint of reliably stopping the booster piston 41, the rearward force by the second electric motor 31B may be made larger than the forward force by the hydraulic fluid in the head side chamber 35h and the rear side chamber 35a. The difference therebetween may be set appropriately. The greater the difference between the two forces, the more reliably the booster piston 41 can be stopped, while the smaller the difference between the two forces, the easier it is to reduce the power consumption of the second electric motor 31B. For example, the rearward force by the second electric motor 31B may be set to 1.5 times or less, 1.2 times or less, or 1.1 times or less of the forward force by the hydraulic fluid.

[0161] The timing to start supplying the hydraulic fluid to the rear chamber 35a and the timing to start driving the second electric motor 31B may be, for example, approximately the same. From the viewpoint of reliably preventing the forward movement of the booster piston 41, the latter may be made earlier than the former. In this case, the difference between the two timings may be appropriately set. The greater the difference between the two timings, the more reliably the forward movement of the booster piston 41 can be stopped, while the smaller the difference between the two timings, the easier it is to reduce the power consumption of the second electric motor 31B. For example, when the timing to start driving the second electric motor 31B is earlier than the timing to start supplying the hydraulic fluid to the rear chamber 35a, the difference between the two may be 50 msec or less, 20 msec or less, or 10 msec or less.

[0162] In the description of this embodiment, the timing to start supplying the hydraulic fluid to the rear chamber 35a may be the timing of outputting a control command to the hydraulic circuit 53 (a valve, not shown, that controls the pilot pressure to the check valve 59E), or may be the timing when the hydraulic fluid is actually supplied to the rear chamber 35a (which has a control delay with respect to the timing of outputting the control command). In the description of this embodiment, the timing to start driving the second electric motor 31B may be either the timing of outputting a control command to the second electric motor 31B or the timing when the second electric motor 31B actually starts driving. However, the difference between the two is generally negligible.

[0163] The timing to start preparation for boosting by the booster piston 41 (the timing to start supplying the hydraulic fluid to the rear side chamber 35a and / or the timing to start driving the second electric motor 31B) may be set to an appropriate time. The closer the preparation start timing is to the pressure boost start timing by the booster piston 41, the easier it is to reduce the power consumption of the second electric motor 31B. For example, the preparation start timing may be set to after time t2, after time t3, or after time t4. In the illustrated example, the preparation start timing is set within the period from time t3 to time t5. In other words, the period is the period from the start of deceleration to the completion of boosting by supplying the hydraulic fluid to the head side chamber 35h. The preparation start timing may be set to be before time t5, and the time difference from time t5 may be a predetermined time length (for example, 100 msec). If the power consumption is ignored, the preparation start timing may be set to be earlier than the various times exemplified above.

[0164] The control of the second electric motor 31B when the booster piston 41 is stopped as described above may be, for example, torque control. Specifically, the control device 5 may control the torque of the second electric motor 31B so as to maintain a constant torque. The control may be feedback control based on a sensor that detects the torque of the second electric motor 31B, or open control without feedback. Note that the control of the second electric motor 31B when the booster piston 41 is stopped may also be position control or speed control.

[0165] (Boost by boost piston: t5~t6) When a predetermined boost switching condition is satisfied, the control device 5 closes the flow control valve 55 and the check valve 59A. This prohibits backflow of the working fluid from the head side chamber 35h to the accumulator 47. As described with reference to FIG. 4, the control device 5 also makes the rearward force applied by the second electric motor 31B to the booster piston 41 smaller than the forward force applied by the working fluid to the booster piston 41. This causes the pressure in the head side chamber 35h to increase, and boosting is performed.

[0166] The check valve 59A may be automatically closed by the pressure of the hydraulic fluid in the head side chamber 35h. Specifically, when the injection piston 37 is moving forward, the volume of the head side chamber 35h expands, the pressure of the head side chamber 35h is lower than the pressure of the accumulator 47, and the check valve 59A does not automatically close. After that, when the molding material is mostly filled in the cavity 107 and the expansion of the volume of the head side chamber 35h mostly stops, the pressure boosting action of the booster piston 41 makes the pressure of the head side chamber 35h higher than the pressure of the accumulator 47. This causes the check valve 59A to automatically close.

[0167] The pressure increase switching condition may be, for example, that the injection pressure based on the detection value of the pressure sensor 97H that detects the pressure of the head side chamber 35h (and the pressure sensor 97R that detects the pressure of the rod side chamber 35r as necessary) has reached a predetermined pressure, or that the detection position of the plunger 21 detected by the position sensor 99 has reached a predetermined position. In other words, the pressure increase switching condition may be a condition similar to the pressure increase start condition, but different from the pressure increase start condition in terms of the specific pressure or position that serves as the judgment criterion.

[0168] The control when the pressure is increased by the second electric motor 31B is, for example, pressure control based on the detection value (detection value of the injection pressure) of the pressure sensor 97H (and the pressure sensor 97R as necessary). For example, the control device 5 feedback-controls the second electric motor 31B so that the detection value of the injection pressure increases along a predetermined pressure increase curve. As a result, the injection pressure is controlled based on the casting pressure P E (Final pressure).

[0169] The shape of the pressure rise curve is arbitrary. In the illustrated example, the line showing the injection pressure before time t5 and the line showing the injection pressure after time t5 are straight lines with the same slope (rate of change). This is merely one example. Unlike the illustrated example, the pressure rise curve may be a curve whose slope gradually decreases before and after time t5, or the slope and / or shape may be different before and after time t5.

[0170] When pressure control is performed by the second electric motor 31B, the pressure applied from the accumulator 47 to the rear chamber 35a is, for example, constant. In the description here, pressure drops caused by the release of hydraulic fluid from the accumulator 47 to the rear chamber 35a, etc., are ignored. Specifically, for example, the control device 5 applies a constant pressure to the rear chamber 35a by maintaining the opening of the flow control valve 55 constant. This results in pressure control being only electric control rather than a combination of hydraulic control and electric control, improving the accuracy of control. However, electric control may be combined with hydraulic control.

[0171] In the pressure control, the force applied backward by the second electric motor 31B to the booster piston 41 is finally set to 0. For example, the control device 5 finally sets the second electric motor 31B in a torque-free state (a state in which no power is supplied and no driving force is generated). Therefore, the casting pressure P E is determined by two factors, for example, the pressure of the accumulator 47 and the boost ratio of the booster piston 41 (the ratio of the pressure-receiving area in the head side chamber 35h to the pressure-receiving area in the rear side chamber 35a). Therefore, by setting the pressure of the accumulator 47 before the start of injection to an arbitrary pressure, the desired casting pressure P E is realized.

[0172] Unlike the present embodiment, the second electric motor 31B is E When the pressure reaches the pressure increasing pressure P, a rearward force may be applied to the booster piston 41. Here, unlike the present embodiment, no working fluid is supplied to the rear chamber 35a, and a forward force is applied to the booster piston 41 by the second electric motor 31B to increase the casting pressure P E Consider a comparative example in which the casting pressure P E In order to obtain the casting pressure P E In order to obtain the casting pressure P E When the pressure-increasing piston 41 reaches the pressure-increasing position, the force applied rearward by the second electric motor 31B to the booster piston 41 may be set to less than half the force applied forward by the accumulator 47 to the booster piston 41.

[0173] Also, unlike this embodiment, the force applied by the second electric motor 31B to the booster piston 41 may be changed from a rearward force to a forward force during the pressure control process. Then, finally, both the forward force by the working fluid and the forward force by the second electric motor 31B are applied to the booster piston 41 to obtain the casting pressure P E In this case, the casting pressure P EIn order to obtain the above, the force applied forward by the second electric motor 31B to the booster piston 41 is, of course, equal to the casting pressure P E This is smaller than the force that the second electric motor 31B applies forward to the booster piston 41 to obtain the above-mentioned force.

[0174] Also, unlike this embodiment, the discharge of the working fluid from the rod side chamber 35r may be prohibited at an appropriate time before the completion of the pressure increase. In other words, the pressure in the rod side chamber 35r may not ultimately be the tank pressure. In this case, the pressure of the working fluid in the rod side chamber 35r (from another point of view, the timing for prohibiting the discharge of the working fluid from the rod side chamber 35r) may be set to the casting pressure P E will be added to the factors that determine

[0175] In this embodiment, the pressure-increasing start condition and the pressure-increasing switch condition are set so that an initial part of the pressure-increasing process is performed by supplying the working fluid from the accumulator 47 to the head side chamber 35h. However, the pressure-increasing start condition and the pressure-increasing switch condition may be integrated by performing the entire pressure-increasing process only by the action of the pressure-increasing piston 41 (pressure control based on the pressure sensor is not performed when the working fluid is being supplied from the accumulator 47 to the head side chamber 35h).

[0176] Unlike this embodiment, the timing when the flow control valve 55 and the check valve 59A are closed and the timing when the controller 5 starts pressure control by the second electric motor 31B may be different. In other words, the condition when the flow control valve 55 and the check valve 59A are closed and the condition when the pressure control by the second electric motor 31B is started may be different.

[0177] (Holding pressure: t6~t7) The control device 5 controls the casting pressure P E When this is obtained, the casting pressure P EThat is, pressure maintenance is performed. Specifically, for example, the second electric motor 31B is maintained in a torque-free state. Also, the application of pressure from the accumulator 47 to the rear chamber 35a is continued. In the explanation of pressure boosting by the booster piston 41, the second electric motor 31B is not made torque-free and the casting pressure P E In these modified examples, the casting pressure P E may be maintained in the state in which it was obtained.

[0178] While pressure dwell is being performed, the molten metal in the cavity 107 is cooled and solidifies. When the control device 5 determines that the molten metal has solidified (time t7), it controls the hydraulic device 43 (and the second electric motor 31B) to end pressure dwell. For example, the control device 5 closes the flow control valve 55 and the check valve 59E to prohibit the flow of working fluid from the accumulator 47 to the rear chamber 35a. The control device 5 may determine whether the molten metal has solidified as appropriate. For example, the control device 5 determines whether the molten metal has solidified depending on whether a predetermined time has passed since a predetermined time point, such as time t6 when the final pressure was obtained.

[0179] (Detachable part arrives) The speed of the plunger 21 decreases due to the deceleration injection and the pressure increase, and further, pressure holding is started and the plunger 21 stops. Therefore, the detachable part 33 driven by the first electric motor 31A catches up with the detachable part 39z of the piston rod 39. In other words, the detachable part 33 can be in a state where it can be connected to the detachable part 39z.

[0180] The control device 5 stops the first electric motor 31A when it detects that the detachable part 33 has reached a predetermined stop position based on the detection value of a sensor that detects the position of the detachable part 33 (movable member 69) or a sensor that detects the rotation of the first electric motor 31A. The stop position is, for example, the position of the detachable part 33 (a position where the detachable part 33 can be coupled) when the detachable part 33 is coupled to the detachable part 39z (time t11 in the illustrated example), or a position nearby.

[0181] As described above, in the illustrated example, the time when the attachment / detachment unit 33 reaches the stop position is set to be before the time when coupling becomes necessary (time t11 in the illustrated example). The specific time may be set to be an appropriate time. For example, the time may be during deceleration injection, during pressure increase, during pressure holding (in the illustrated example), or after completion of pressure holding (but before coupling).

[0182] (Protrusion motion: t9~t10) After the dwelling is completed, the control device 5 controls the clamping device 7 to move the movable die 105 in a direction away from the fixed die 103 to open the die. The molded product formed by solidifying the molten metal leaves one of the fixed die 103 and the movable die 105 and remains in the other die. After that (or simultaneously with the mold opening), the control device 5 controls an extrusion device (not shown) to extrude the molded product from the other die.

[0183] When the molded product is removed from the fixed mold 103, which is one of the molds, by opening the mold using the mold clamping device 7, or when the molded product is pushed out from the fixed mold 103, which is the other mold, by the extrusion device, the control device 5 may control the injection device 9 to perform an operation of pushing the molded product out of the fixed mold 103 using the plunger 21 (hereinafter sometimes referred to as the ``ejection operation'').

[0184] Specifically, for example, the control device 5 rotates the second electric motor 31B in the forward direction, and pressurizes the working fluid in the head side chamber 35h by the booster piston 41. The control at this time may be speed control or torque control. For example, the control device 5 may perform speed control based on the detected speed of the plunger 21 so that the speed of the plunger 21 becomes the same as the speed of the moving die 105 or the speed of the extrusion pin of the extrusion device (not shown).

[0185] (Plunger retraction: t11~) As described above, the detachable part 33 stops at a position (or near there) where it can be connected to the detachable part 39z of the piston rod 39. When the protruding operation is completed, the control device 5 connects the detachable part 33 to the detachable part 39z. At this time, the position of either the detachable part 33 or the detachable part 39z may be finely adjusted so that they are in a relative position where they can be detached. Thereafter, the control device 5 reverses the first electric motor 31A to move the injection piston 37 backward.

[0186] When the first electric motor 31A is rotated in the reverse direction, the control device 5 opens the flow control valve 55 and the check valve 59A. As a result, the hydraulic fluid discharged from the head side chamber 35h as the injection piston 37 retreats is charged into the accumulator 47. The control device 5 also closes the check valve 59B to prohibit the hydraulic fluid from flowing from the rod side chamber 35r to the tank 51, switches the switching valve 62 to a position that allows the hydraulic fluid to flow from the pump 49 to the rod side chamber 35r, and drives the pump 49. As a result, the hydraulic fluid is supplied from the pump 49 to the rod side chamber 35r.

[0187] Before the period during which the injection piston 37 is retracted by the first electric motor 31A as described above, during at least a part of the period, and / or after the period, the booster piston 41 also retracts. This retraction may be achieved by any of the first electric motor 31A, the second electric motor 31B, and the supply of hydraulic fluid. In addition, the hydraulic fluid discharged from the rear chamber 35a may or may not be filled into the accumulator 47. Specific examples are given below.

[0188] In one example (illustrated example), the control device 5 reverses the second electric motor 31B to retract the booster piston 41 during at least a part of the period during which the first electric motor 31A is reversed to retract the injection piston 37. When the booster piston 41 is retracted, the control device 5 opens the flow control valve 55 and the check valve 59E. This causes the working fluid discharged from the rear side chamber 35a to fill the accumulator 47. The torque or speed of the second electric motor 31B may be set appropriately. For example, the speed of the booster piston 41 is slower than the speed of the injection piston 37. As a result, the working fluid is discharged from the head side chamber 35h throughout the period during which the injection piston 37 retracts. However, there may be a period during which the booster piston 41 retracts only during a part of the period during which the injection piston 37 retracts, and the speed of the booster piston 41 is equal to or higher than the speed of the injection piston 37, and the working fluid is not discharged from the head side chamber 35h.

[0189] In another example, during a part (for example, the beginning) of the period in which the first electric motor 31A is rotated in the reverse direction to move the injection piston 37 backward, the control device 5 opens the flow control valve 55 and the check valve 59E, and closes the check valve 59A (prohibiting the discharge of the working fluid from the head side chamber 35h). As a result, the booster piston 41 moves backward as the injection piston 37 moves backward, and the working fluid discharged from the rear side chamber 35a is filled into the accumulator 47. The check valve 59A may be automatically closed. While the booster piston 41 moves backward, the second electric motor 31B may be in a torque-free state or may be rotated in the reverse direction. When the second electric motor 31B is rotated in the reverse direction, the second electric motor 31B may be simply controlled so that the second drive device 29B does not hinder the booster piston 41 from moving backward, or may apply a rearward force to the booster piston 41. In the latter case, the roles of the first electric motor 31A and the second electric motor 31B may be appropriately set (it does not matter which one generates larger torque). Conversely to the above, the retraction of the booster piston 41 may be realized mainly by the reverse rotation of the second electric motor 31B, and the reverse rotation of the first electric motor 31A may only retract the injection piston 37 so that the volume of the head side chamber 35h does not increase.

[0190] Unlike the illustrated example, the detachable part 33 may be connected to the detachable part 39z after the detachable part 33 catches up with the detachable part 39z and before the need for connection arises. For example, the detachable part 33 may be connected to the detachable part 39z during pressure retention or after pressure retention is completed (but before the need for connection arises).

[0191] As described above, the injection piston 37 and the booster piston 41 are retracted, and then the various valves are closed, whereby the injection unit 9 returns to its initial state. In other words, the injection unit 9 is ready for the next molding cycle (injection cycle).

[0192] As described above, the injection device 9 according to the embodiment includes the injection cylinder 27, the hydraulic device 43, the electric motor 31 (the second electric motor 31B), and the control device 5. The injection cylinder 27 is connected to the plunger 21 that pushes out the molding material M into the die (the mold 101). The injection cylinder 27 also includes a piston (the booster piston 41) that is movable in a first direction (forward) and a second direction (backward) opposite thereto. The hydraulic device 43 supplies hydraulic fluid to the injection cylinder 27. The second electric motor 31B is (indirectly) connected to the booster piston 41. The control device 5 controls the hydraulic device 43 and the second electric motor 31B to simultaneously apply a first forward force by the hydraulic fluid and a second backward force by the second electric motor 31B that is smaller than the first force to the booster piston 41, thereby moving the booster piston 41 forward.

[0193] 4 and the like, the force in the drive direction of the booster piston 41 can be obtained by the hydraulic device 43, and the force can be controlled by the second electric motor 31B that generates a force in the opposite direction to the drive direction. As a result, for example, it is possible to reduce power consumption while improving the accuracy of control.

[0194] The injection cylinder 27 may be coupled to the plunger 21 such that movement of the booster piston 41 in the first direction causes the plunger 21 to advance toward the mold 101. In another aspect, the first direction may be forward.

[0195] In this case, for example, the above-mentioned hybrid driving mode (mode in which a force in a first direction by the hydraulic fluid and a force in a second direction by the second electric motor 31B are applied to the booster piston 41) is realized in the operation of pushing out the molding material toward the die 101. Usually, the operation of pushing out the molding material toward the die 101 requires a large force. Therefore, by realizing the above-mentioned driving mode in such an operation, for example, the effect of reducing power consumption is improved.

[0196] Conversely, the direction in which the piston moves so that the plunger 21 retreats may be defined as the first direction, and the opposite direction may be defined as the second direction, and an operation may be performed in which a first force in the first direction by the hydraulic fluid and a force in the second direction by the electric motor that is smaller than the first force are applied to the piston. In this case as well, for example, the effect of improving the accuracy of control while reducing power consumption with respect to the retreat of the plunger 21 is expected. Such a retreat operation may or may not be combined with the operation related to pressure increase and pressure maintenance in the embodiment.

[0197] The injection cylinder 27 may be of a booster type. That is, the injection cylinder 27 may have an injection piston 37 connected to a rear portion of the plunger 21, and a booster piston 41 capable of pressurizing the hydraulic fluid behind the injection piston 37. Then, the above-mentioned operation of applying a first force in a first direction by the hydraulic fluid and a force in a second direction by the second motor 31B, which is smaller than the first force, to the booster piston 41 may be performed. From another perspective, the control device 5 may control the hydraulic device 43 and the second motor 31B to simultaneously apply a first force in a first direction (forward) by the hydraulic fluid and a second force in a second direction (rearward) by the second motor 31B, which is smaller than the first force, to the piston (for example, the booster piston 41), thereby boosting the pressure. The control device 5 may control the second motor 31B so that the second force changes with time when the boosting is being performed.

[0198] In this case, in boosting requiring a relatively large force, a first force by the hydraulic fluid and a second force by the electric motor are applied to the piston. Therefore, for example, the effect of reducing power consumption is improved. Also, as will be described in detail in the explanation of a modified example (FIG. 12(a)) to be described later, it is easier to reduce the size of the second drive unit 29B compared to an embodiment in which the second drive unit 29B is provided in a single-barrel injection cylinder that does not have a booster piston 41.

[0199] The control device 5 may control the hydraulic device 43 and the second electric motor 31B to apply a first force in a first direction (forward) to a piston (e.g., the booster piston 41) by the hydraulic fluid while keeping the second electric motor 31B in a state in which it does not generate driving force, thereby maintaining pressure.

[0200] In this case, the effect of reducing power consumption is improved. And / or the second motor 31B can be easily made smaller. By making the second motor 31B smaller, it becomes easier to use a commercially available motor as the second motor 31B. Due to these circumstances, for example, it becomes easier to set the pressure retention time to a long time (for example, 10 seconds or more).

[0201] The hydraulic device 43 may include an accumulator 47. The control device 5 may control the hydraulic device 43 so as to apply the hydraulic pressure of the accumulator 47 to the rear of the booster piston 41, thereby maintaining pressure.

[0202] In this case, for example, the force required for maintaining pressure can be obtained simply by connecting the accumulator 47 to the rear chamber 35a. Therefore, the effect of reducing power consumption is improved compared to, for example, a mode in which pressure is maintained by applying hydraulic pressure to the rear chamber 35a by the pump 49 (such a mode is also included in the technology according to the present disclosure). Note that even in the mode in which hydraulic pressure from the accumulator 47 is applied to the rear chamber 35a, hydraulic fluid may be replenished from the pump 49 to the rear chamber 35a in response to leakage of hydraulic fluid, for example.

[0203] The control device 5 may control the hydraulic device 43 and the second electric motor 31B to simultaneously apply a first force in a first direction (forward) by the hydraulic fluid and a third force in a second direction (rearward) by the second electric motor 31B, which is greater than the first force, to a piston (e.g., the booster piston 41), thereby bringing the booster piston 41 into a stopped state at the rear drive limit. The control device 5 may also control the hydraulic device 43 and the second electric motor 31B to gradually reduce the third force, thereby making the rearward force by the second electric motor 31B a second force smaller than the first force, thereby starting the forward movement of the booster piston 41.

[0204] In this case, for example, the booster piston 41 starts moving by controlling the second electric motor 31B. On the other hand, the responsiveness of the control of the second electric motor 31B is higher than the responsiveness of the control of the hydraulic device 43. Therefore, the accuracy of the control of the booster piston 41's boost start timing can be improved. For example, unlike the embodiment, consider a mode in which the check valve 59E is opened to start the supply of hydraulic fluid from the accumulator 47 to the rear chamber 35a to start the advancement of the booster piston 41 (this mode is also included in the technology according to the present disclosure). In this mode, the time from when the control device 5 outputs a control command to the hydraulic device 43 to when the booster piston 41 starts advancing is, for example, 20 msec or more. On the other hand, in this embodiment, the time from when the control device 5 outputs a control command to the second electric motor 31B to when the booster piston 41 starts advancing can be 10 msec or less.

[0205] <Modification> Various modified examples will be described below.

[0206] (Modification of protruding operation) In the embodiment, the ejection operation (times t9 to t10) in which the plunger 21 pushes the molded product away from the fixed die 103 is performed by the second driving device 29B. The ejection operation may be performed by the first driving device 29A in addition to or instead of the second driving device 29B.

[0207] The dashed lines in "First Motor", "Second Motor" and "Detach" in FIG. 10 indicate the operation of such a modified example. For example, the control device 5 first connects the detachable portion 33 to the detachable portion 39z of the piston rod 39. Next, the control device 5 rotates the first motor 31A in the normal direction to advance the piston rod 39. This causes the plunger 21 to push the molded product, and the product is released from the mold. At this time, the second motor 31B is stopped, for example. The rod side chamber 35r and the head side chamber 35h may be connected to the tank 51, for example. Alternatively, the pump 49 may supply hydraulic fluid to the head side chamber 35h. The head side chamber 35h may be sealed, and the second motor 31B may be rotated in the normal direction.

[0208] Although not particularly shown, in the protruding operation, the force of the hydraulic fluid may be used instead of or in addition to the force of the electric motor. For example, the hydraulic fluid may be supplied from the accumulator 47 or the pump 49 to the head side chamber 35h, and the pressure of the head side chamber 35h may contribute to the discharge operation.

[0209] Furthermore, if the detachable portion 33 is used only to retract the plunger 21, as in the embodiment, it may be configured in such a way that only rearward relative movement with respect to the detachable portion 39z is prohibited (and permitted) (forward relative movement is not prohibited).

[0210] (Modification regarding the start time of boosting by the booster piston) FIG. 11 is a diagram showing a modification relating to the timing at which boosting by the booster piston 41 starts, and corresponds to a part of FIG.

[0211] In Fig. 10, the time when pressure increase by supplying hydraulic fluid to the head side chamber 35h ends (time t5) and the time when pressure increase by the booster piston 41 starts (time t5) are the same. On the other hand, in Fig. 11, the time ts when pressure increase by the booster piston 41 starts is later than the time t5 when pressure increase by supplying hydraulic fluid to the head side chamber 35h ends. The time difference between the two may be set appropriately.

[0212] The injection device 9 may be configured so that the user can set the time difference between time t5 and time ts. In this case, the time difference may be set to 0. In other words, the operation modes of Figs. 10 and 11 may be selectively realized in the same injection device 9. For example, the time difference may be set in the range of 0 to 100 msec. Of course, the operation mode of Fig. 10 and the operation mode of Fig. 11 may be operation modes of different injection devices 9.

[0213] In the description of the embodiment, the timing at which the booster piston 41 starts preparation for boosting (the state in which the booster piston 41 is stopped at the backward limit by the second electric motor 31B shown in FIG. 3) is before time t5 (the completion time of boosting by the injection piston 37). In an embodiment in which it is essential that time ts is after time t5, the booster piston 41 can also start preparation for boosting after time t5.

[0214] (Modification of injection cylinder) FIG. 12(a) is a schematic diagram showing a modified example of the injection cylinder.

[0215] The illustrated injection cylinder 27A is a so-called single-barrel type that does not have a booster piston 41. In an embodiment having this injection cylinder 27A, for example, injection in the narrow sense (for example, low-speed injection and high-speed injection), boosting, and pressure maintenance are all performed by supplying hydraulic fluid to the rear of the injection piston 37. In addition, the electric motor 31 is connected to the injection piston 37. In this modified example, in boosting, a rearward force (second force) is applied to the injection piston 37 by the electric motor 31, as shown by the arrow a4. This force is made smaller than the forward force (first force) applied to the injection piston 37.

[0216] In this way, the operation of applying the force of the hydraulic fluid and the force of the electric motor to the piston in opposite directions to move the piston in the direction of the force of the hydraulic fluid (first direction) may be applied to the single-barrel injection cylinder 27A. The moving distance of the injection piston 37 is longer than the moving distance of the booster piston 41. Therefore, in this embodiment, the length of the second screw shaft 73B can be made shorter than the modified example of FIG. 12(a).

[0217] Note that, instead of or in addition to the electric motor 31 shown in the modified example of FIG. 12(a), a rearward force smaller than the forward force of the hydraulic fluid may be applied to the injection piston 37 by the first drive device 29A of the embodiment. Also, a rearward force smaller than the forward force of the hydraulic fluid may be applied in injection in the narrow sense (for example, low-speed injection and high-speed injection) in addition to or instead of boosting. In this case, speed control may be performed by an electric drive unit. These matters are similar to the aspect in which a booster piston 41 is provided.

[0218] As shown in FIG. 12(d), the injection cylinder 27D may be one in which a first cylinder member 35p accommodating the injection piston 37 and a second cylinder member 35q accommodating the booster piston 41 are separated, and a head side chamber 35h behind the injection piston 37 and a pressurizing chamber 35b in front of the booster piston 41 are communicated with each other by a communication passage 35c. In this case, the position and orientation of the second cylinder member 35q relative to the first cylinder member 35p are arbitrary. Furthermore, the position and orientation of the electric drive unit that drives the booster piston 41 are also arbitrary. For example, the second cylinder member 35q may be arranged in parallel with the first cylinder member 35p (example shown in the figure) or may be arranged to intersect with the first cylinder member 35p. As can be understood from the example shown in the figure, the direction in which the booster piston 41 moves during boosting (one example of the first direction) may be backward with respect to the plunger 21 and the injection piston 37, opposite to the first embodiment.

[0219] (Modifications related to the electric drive device) The mechanism for converting the rotation of the electric motor 31 (first electric motor 31A and / or second electric motor 31B) into linear motion is not limited to a screw mechanism. For example, as shown in FIG. 12(b), the conversion mechanism 68C may be a rack-and-pinion mechanism. Although not specifically shown, the conversion mechanism may be a link mechanism. The electric drive device (first drive device 29A or second drive device 29B) may not have a transmission mechanism (first transmission mechanism 67A and / or second transmission mechanism 67B) that transmits rotation, or may have another type of transmission mechanism. An example of another type of transmission mechanism is a gear mechanism.

[0220] The electric motors (first electric motor 31A and / or second electric motor 31B) may be linear motors. In Fig. 12(c), the electric motor 31C that drives the booster piston 41 is a linear motor. The electric motor 31C has, for example, a mover 31a fixed to the booster piston 41 and made up of one of a magnet and a coil, and a stator 31b fixed to a stationary part of the injection device 9 (for example, a frame 45) and made up of the other of a magnet and a coil.

[0221] The present invention is not limited to the above-described embodiment and modifications, and may be implemented in various forms.

[0222] The molding machine is not limited to a die-casting machine. For example, the molding machine may be another metal molding machine, an injection molding machine, or a molding machine that molds a material in which a thermoplastic resin or the like is mixed with wood powder. The molding machine is not limited to a horizontal clamping and horizontal injection machine, and may be, for example, a vertical clamping and vertical injection machine, a vertical clamping and horizontal injection machine, or a horizontal clamping and vertical injection machine. The plunger may be in the shape of a screw. The die-casting machine is not limited to a cold chamber machine, and may be, for example, a hot chamber machine. The working fluid is not limited to oil, and may be, for example, water.

[0223] In the embodiment, an injection device in which the retraction of the injection piston (plunger) and the charging of the accumulator are performed by an electric motor has been exemplified. However, the retraction of the injection piston (plunger) and / or the charging of the accumulator may be performed by supplying hydraulic fluid from a pump, not by an electric motor. Also, in the embodiment, the advancement of the injection piston (injection in the narrow sense from another point of view) is performed only by supplying hydraulic fluid to the rear of the injection piston. However, at least a part or all of the injection in the narrow sense may be performed by an electric motor.

[0224] As described in the embodiment, the hydraulic device (hydraulic circuit) shown in FIG. 9 is merely an example and may be modified as appropriate.

[0225] For example, instead of or in addition to the meter-in circuit, a meter-out circuit may be provided. That is, a flow control valve that controls the flow rate of the hydraulic fluid discharged from the rod side chamber 35r may be provided, and the injection speed and / or injection pressure may be controlled by the flow control valve.

[0226] Also, for example, a run-around circuit may be provided that supplies the working fluid discharged from the rod side chamber 35r to the head side chamber 35h. The run-around circuit may be combined with a meter-in circuit and / or a meter-out circuit. When combined with a meter-out circuit, the run-around circuit may connect a position on the rod side chamber 35r side of the flow control valve of the meter-out circuit to the head side chamber 35h, or may connect a position on the tank side of the flow control valve of the meter-out circuit to the head side chamber 35h.

[0227] In the embodiment, the accumulator that supplies the hydraulic fluid to the head side chamber 35h and the accumulator that supplies the hydraulic fluid to the rear side chamber 35a are the same accumulator. Unlike the embodiment, the accumulator that supplies the hydraulic fluid to the head side chamber 35h and the accumulator that supplies the hydraulic fluid to the rear side chamber 35a may be separate accumulators.

[0228] In the description of the embodiments, for convenience, each valve is named by the name of the type of valve illustrated in the drawings (check valve, switching valve), but each valve may be a valve of a type other than the one named.

[0229] In the embodiment, the pilot pressure for the various valves is supplied from the accumulator. However, the pilot pressure may be supplied from a pump or may be supplied from an accumulator separate from the accumulator for driving the plunger.

[0230] In the embodiment in which the rod side chamber is filled with hydraulic fluid, hydraulic fluid may be supplied to the rod side chamber from an accumulator other than the accumulator for driving the plunger when the piston retracts. The pressure of this accumulator for supply may be lower than that of the accumulator for driving the plunger.

[0231] In the embodiment, while the booster piston 41 is provided, the pressure is also boosted by supplying the hydraulic fluid to the head side chamber. However, this boosting by supplying the hydraulic fluid to the head side chamber does not have to be performed. In other words, when the hydraulic fluid is being supplied to the head side chamber, only the speed control may be performed. [Explanation of symbols]

[0232] 1...die casting machine (molding machine), 5...control device, 9...injection device, 19...sleeve, 21...plunger, 27...injection cylinder, 31B...second electric motor (electric motor), 41...boosting piston (piston), 43...hydraulic device, 101...mold (die), 107...(die) cavity.

Claims

1. an injection cylinder connected to a plunger for extruding a molding material into a mold, the injection cylinder having a first piston movable in a first direction and a second direction opposite thereto, the first piston being capable of driving the plunger without or through a hydraulic fluid by movement in the first direction; a hydraulic device for supplying hydraulic fluid to the injection cylinder; an electric motor coupled to the first piston; a control device that controls the hydraulic device and the electric motor to simultaneously apply to the first piston a first force in the first direction by a hydraulic fluid and a second force in the second direction by the electric motor, the second force being smaller than the first force, thereby moving the first piston in the first direction; and The injection device has

2. The injection cylinder is connected to the plunger such that the movement of the first piston in the first direction causes the plunger to advance in a direction for extruding the molding material into the mold. The injection device according to claim 1 .

3. The injection cylinder is an injection piston connected to a rear portion of the plunger; a booster piston as the first piston, capable of pressurizing the hydraulic fluid behind the injection piston.

3. The injection device according to claim 2.

4. The control device controls the hydraulic device and the electric motor to simultaneously apply to the first piston the first force in the first direction by the hydraulic fluid and the second force in the second direction by the electric motor, the second force being smaller than the first force, thereby increasing pressure.

4. An injection device according to claim 2 or 3.

5. The control device controls the electric motor so that the second force changes over time while the pressure is being boosted.

5. The injection device according to claim 4.

6. The control device controls the hydraulic device and the electric motor so that the first force in the first direction by the hydraulic fluid continues to be applied to the first piston after pressure boosting, while the electric motor is placed in a state in which it does not generate a driving force, thereby maintaining pressure.

6. An injection device according to claim 4 or 5.

7. The hydraulic device includes an accumulator, The control device controls the hydraulic device to apply the hydraulic pressure of the accumulator to the rear of the first piston, thereby performing the pressure maintenance.

7. The injection device according to claim 6.

8. The control device includes: applying to the first piston a first force in the first direction by the hydraulic fluid and a third force in the second direction by the electric motor, the third force being greater than the first force, thereby bringing the first piston into a stopped state in which it is stopped at a drive limit in the second direction; By gradually reducing the third force, the force in the second direction by the electric motor becomes the second force which is smaller than the first force, thereby starting the movement of the first piston in the first direction; The hydraulic device and the electric motor are controlled so as not to move the first piston in the second direction during the period from the start of injection to the completion of pressure holding. The injection device according to any one of claims 1 to 7.

9. An injection device according to any one of claims 1 to 8; A mold clamping device for holding the mold; The molding machine has

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