Injection device and molding machine

Abstract

The first valve (39A) and the second valve (39B) are connected in parallel to each other and together constitute an outlet throttle circuit (37A) or an inlet throttle circuit (37B) of the injection cylinder (27). The controller (5) opens the first valve (39A) and opens the second valve (39B) in a single molding cycle. Furthermore, the controller (5) outputs control signals (SG1 and SG2), which are different from each other, to the first valve (39A) and the second valve (39B) during at least a part of the period during the one-time molding cycle.

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 Art

[0002] A known injection device (for example, Patent Documents 1 to 6) injects a molding material (for example, molten metal) into a mold by the driving force of a hydraulic injection cylinder (for example, an oil hydraulic cylinder). Further, as a mechanism for controlling the speed of the injection cylinder (in another aspect, the injection speed), an outlet throttle circuit for controlling the flow rate of the working fluid (for example, working oil) discharged from the injection cylinder and an inlet throttle circuit for controlling the flow rate of the working fluid supplied to the injection cylinder are known. The higher the flow rate is made by the outlet throttle circuit and / or the inlet throttle circuit, the higher the injection speed becomes.

[0003] Patent Document 1 discloses an injection device having two servo valves connected in parallel to each other and together constituting an outlet throttle circuit. In a molding cycle in which the injection speed set via an input device is higher than a specified threshold value, both of the two servo valves are opened and used together. Further, in a molding cycle in which the injection speed set via the input device is equal to or lower than the threshold value, only one of the two servo valves is opened and used, and the other is kept closed and not used. It should be noted that in Patent Document 1, no specific control method when both of the two servo valves are opened in one molding cycle is mentioned.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2022-89708

[0007] Patent Document 2: Japanese Unexamined Patent Application Publication No. 2004-66253

[0008] Patent Document 3: Japanese Unexamined Patent Application Publication No. 2009-107010

[0009] Patent Document 4: Japanese Unexamined Patent Application Publication No. 2008-80364

[0010] Patent Document 5: Japanese Unexamined Patent Application Publication No. 2019-72751

[0011] Patent Document 6: Japanese Unexamined Patent Application Publication No. 2022-56033 Summary of the Invention

[0012] Technical Problem to be Solved by the Invention

[0013] For example, an injection device and a molding machine that can improve the control accuracy of the injection speed are expected.

[0014] Technical solution for solving technical problems

[0015] An injection device according to one aspect of the present disclosure includes an injection cylinder, a first flow control valve, a second flow control valve, and a controller. The injection cylinder is connected to a plunger that injects a molding material into a mold. The first flow control valve and the second flow control valve are connected in parallel with each other to together form an outlet throttling circuit or an inlet throttling circuit of the injection cylinder. The controller sets the first flow control valve to an open state and the second flow control valve to an open state within one molding cycle.

[0016] In one example, within the one molding cycle, the controller outputs different control signals to the first flow control valve and the second flow control valve during at least a part of the period.

[0017] In one example, within the one molding cycle, the controller controls the first flow control valve and the second flow control valve according to different algorithms during at least a part of the period.

[0018] In one example, within the one molding cycle, the controller causes the first flow control valve and the second flow control valve to perform different actions during at least a part of the period.

[0019] A molding machine according to one aspect of the present disclosure includes any of the above injection devices and a mold clamping device that holds the mold.

[0020] Advantages of the invention

[0021] According to the above structure, for example, the control accuracy of the injection speed can be improved. Description of the drawings

[0022] Figure 1 It is a side view showing the structure of the main part of a die-casting machine according to an embodiment.

[0023] Figure 2 It shows Figure 1 A schematic diagram of a first circuit example of the injection device of the die-casting machine.

[0024] Figure 3 It shows Figure 1 A schematic diagram of a second circuit example of the injection device of the die-casting machine.

[0025] Figure 4 It is a diagram for explaining the operation of the injection device according to the embodiment.

[0026] Figure 5It is a diagram showing the first operation example and the second operation example of the flow control valve of the injection device according to the embodiment.

[0027] Figure 6 It is for Figure 5 a diagram explaining the effects of the first operation example and the second operation example.

[0028] Figure 7 It is a diagram showing the third operation example of the flow control valve of the injection device according to the embodiment.

[0029] Figure 8 It is a diagram showing the fourth operation example of the flow control valve of the injection device according to the embodiment.

[0030] Figure 9 It is a diagram showing the fifth operation example of the flow control valve of the injection device according to the embodiment.

[0031] Figure 10 It is a diagram showing the sixth operation example of the flow control valve of the injection device according to the embodiment.

[0032] Figure 11 It is a diagram showing an example of the steps of the process executed by the injection device according to the embodiment.

[0033] Figure 12 It is a diagram showing the first structural example of the structure of the control system of the injection device according to the embodiment.

[0034] Figure 13 It is a diagram showing the second structural example of the structure of the control system of the injection device according to the embodiment.

[0035] Figure 14 It is showing Figure 13 the first specific example of the control system of the second structural example.

[0036] Figure 15 It is showing Figure 13 the second specific example of the control system of the second structural example.

[0037] Figure 16 It is showing Figure 13 the third specific example of the control system of the second structural example. Detailed implementation mode

[0038] Hereinafter, multiple aspects of the present disclosure will be described with reference to the accompanying drawings. In addition, it should be noted that for the aspects described relatively later among the multiple aspects, only the differences from the aspects described earlier will be basically described. For matters not particularly mentioned, they may be the same as or analogized from the aspects described earlier. Also, for the structures corresponding to each other among the multiple aspects, even if there are differences, for convenience, the same reference numerals will be used to label them.

[0039] (Outline of the injection device of the embodiment)

[0040] Figure 2 It is a schematic diagram showing the structure of the injection device 9A of the embodiment. It should be noted that in the description of the injection device 9A, terms such as forward may be used with the left side of Figure 2 being the front.

[0041] The injection device 9A extrudes (injects) a molten solution (an example of a molding material, molten metal) (not shown) in the sleeve 21 into the mold 101 (inside the space 107) through the plunger 23. A molded part (die-cast part) is produced by solidifying the molten solution injected into the mold 101. The plunger 23 is driven by the injection cylinder 27.

[0042] The injection cylinder 27 has a cylinder member 29, a piston 31, and a piston rod 33. The piston 31 slides axially in the cylinder member 29. The piston rod 33 is fixed to the piston 31 and extends from the cylinder member 29. The inside of the cylinder member 29 is divided by the piston 31 into a rod-side chamber 29r on the piston rod 33 side and a head-side chamber 29h on the opposite side. The cylinder member 29 does not move. The front end of the piston rod 33 is connected to the rear end of the plunger 23 through a coupling 25.

[0043] By supplying a working fluid (e.g., working oil) to the head-side chamber 29h, the piston 31 advances. Thereby, the plunger 23 connected to the piston 31 via the piston rod 33 and the coupling 25 advances. Furthermore, injection is performed. When the piston 31 advances, the working fluid is discharged from the rod-side chamber 29r.

[0044] The injection device 9A has an outlet throttle circuit 37A for controlling the flow rate of the working fluid discharged from the rod-side chamber 29r. The advancing speed of the plunger 23 (in other words, the injection speed) is controlled by controlling the flow rate discharged from the rod-side chamber 29r.

[0045] Figure 3 It is a schematic diagram showing the structure of another example of the injection device 9B of the embodiment.

[0046] Figure 2 The injection device 9A of Figure 3The main difference of the injection device 9B is that the injection device 9A has an outlet throttling circuit 37A, while the injection device 9B has an inlet throttling circuit 37B. The inlet throttling circuit 37B controls the flow rate of the working fluid supplied to the cephalic chamber 29h. Thereby, the advancing speed of the plunger 23 is controlled.

[0047] In the present embodiment, different from a normal injection device, both the outlet throttling circuit 37A and the inlet throttling circuit 37B have two flow control valves (first valve 39A and second valve 39B) connected in parallel with each other. These two valves are controlled by the controller 5.

[0048] The controller 5 sets both the first valve 39A and the second valve 39B to the open state within one primary molding cycle. In another view, both the first valve 39A and the second valve 39B are used for the discharge of the working fluid or the supply of the working fluid when the plunger 23 advances within the above-mentioned primary molding cycle. In other words, within the primary molding cycle is within the same molding cycle. And the above-mentioned primary molding cycle is, for example, each molding cycle in the repeatedly performed molding cycles.

[0049] Moreover, the controller 5 outputs mutually different control signals SG1 and SG2 to the first valve 39A and the second valve 39B during at least a part of the above-mentioned primary molding cycle. And / or, the controller 5 controls the first valve 39A and the second valve 39B according to mutually different algorithms during the above-mentioned at least a part of the period. And / or, the controller 5 makes the first valve 39A and the second valve 39B perform mutually different actions during the above-mentioned at least a part of the period. And / or, the controller 5 makes the functions of the first valve 39A and the second valve 39B different from each other during the above-mentioned at least a part of the period.

[0050] As mutually different actions, for example, the following actions can be cited. An opening action and a closing action. A gradually opening action (the process of opening) and a gradually closing action (the process of closing). Actions of mutually opening (or gradually opening) but having different opening degrees (and / or flow rates). Actions of mutually opening (or mutually closing) but having different change speeds of the opening degrees (and / or flow rates). Actions of having different patterns of change of the opening degrees (and / or flow rates) with respect to the passage of time.

[0051] As a manner in which the control signals are mutually different, for example, a manner in which the signal levels (such as voltages) of two control signals output in the same period are mutually different can be cited. In addition, a manner in which no control signal is output to the other valve when a control signal is output to one valve can also be understood as a kind of manner in which the control signals are mutually different. The above-mentioned same period may not be strictly the same moment. For example, two moments within the same control cycle, or two moments whose time difference does not bring a significant difference to the control result can be regarded as the same period.

[0052] If the control signals SG1 and SG2 are different from each other, generally the two valves perform different actions. However, theoretically, due to differences in the structures of the two valves, etc., when the two valves perform different actions, it is also possible that the control signals SG1 and SG2 become the same signal.

[0053] As mutually different algorithms, for example, the following algorithms can be cited. Performing an opening action and / or a closing action when a specified condition is satisfied, and controlling such that the above-mentioned specified conditions are different from each other. Open-loop control (another expression is open-loop control) and closed-loop control (another expression is closed-loop control or feedback control). Controls that are both open-loop control or both closed-loop control, but the values of specific parameters (such as gain) are different from each other.

[0054] In the case of controlling two valves according to mutually different algorithms, generally the two control signals SG1 and SG2 (and / or the actions of the two valves) are different from each other. However, as a result, the control signals SG1 and SG2 (and / or the actions of the two valves) sometimes become the same as each other. On the contrary, when controlling two valves according to mutually the same algorithm, due to differences in the structures of the two valves, etc., as a result, there are also cases where the two control signals SG1 and SG2 (and / or the actions of the two valves) are different from each other.

[0055] As mutually different functions, for example, the following functions can be cited. The function of starting and continuing injection, and the function of (not starting injection) continuing injection. The function of making the injection speed approximately close to the target speed, and the function of reducing the influence of interference. The function of making the injection speed approximately close to the target speed, and the function of filling the shortage of flow rate during acceleration. The function of making the injection speed approximately close to the target speed by low-speed injection, and the function of filling the shortage of flow rate by high-speed injection. This is achieved, for example, by mutually different control signals, mutually different algorithms, mutually different actions, and / or mutually different structures of the valves.

[0056] It should be noted that hereinafter, for convenience, without special explanation, sometimes only one of the various viewpoints (control signals, control algorithms, valve actions, valve functions, etc.) for explaining the relationship between the two valves as described above is mentioned. As long as there is no contradiction, etc., the words representing these viewpoints can be mutually replaced.

[0057] The specific manner of controlling and / or operating the two valves as described above can be various, and the effects achieved thereby are also various.

[0058] For example, only one of the two valves is used during a period of low injection speed (low flow rate period) within one molding cycle. Thus, for example, as will be described in detail later, the resolution of control can be improved compared to the case of using two valves. On the other hand, the two valves are used during other periods within one molding cycle. Thus, for example, a large flow rate can be achieved, and the injection speed can be increased accordingly.

[0059] Also, for example, the opening degree of the first valve 39A mainly changes according to the change in the target value of the injection speed, and the opening degree of the second valve 39B mainly changes according to the disturbance. Thus, for example, as will be described in detail later, compared to the way where one valve undertakes two functions, the control of each valve is simplified, and the adjustment of the gain also becomes easier.

[0060] The above is an overview of the injection devices 9 (9A and 9B) of the embodiment. Hereinafter, the embodiment will be described roughly in the following order.

[0061] 1. Structure of the die-casting machine ( Figure 1 )

[0062] 2. Structure of the injection device ( Figure 2 and Figure 3 )

[0063] 2.1. Overall injection device

[0064] 2.2. Injection cylinder

[0065] 2.3. Hydraulic circuit

[0066] 2.4. Flow control valve

[0067] 2.5. Sensor

[0068] 3. Operation of the injection device ( Figure 4 )

[0069] 3.1. Low-speed injection

[0070] 3.2. High-speed injection

[0071] 3.3. Boosting and holding pressure

[0072] 3.4. Other operations

[0073] 4. Operation of the flow control valve

[0074] 4.1. First and second operation examples ( Figure 5 and Figure 6 )

[0075] 4.2. Third and fourth operation examples ( Figure 7 and Figure 8 )

[0076] 4.3. Examples of the Fifth and Sixth Operations Figure 9 and Figure 10 )

[0077] 5. Specific Examples of the Control of the Flow Control Valve

[0078] 5.1. Overall Control

[0079] 5.2. An Example of the Flowchart Figure 11 )

[0080] 5.3. The First Structural Example of the Control System Figure 12 )

[0081] 5.4. The Second Structural Example of the Control System Figure 13 )

[0082] 5.4.1. The First Specific Example of the Second Configuration Example Figure 14 )

[0083] 5.4.2. The Second Specific Example of the Second Configuration Example Figure 15 )

[0084] 5.4.3. The Third Specific Example of the Second Configuration Example Figure 15 )

[0085] 5.5. Other Control Examples

[0086] 6. Summary of the Embodiment

[0087] In the following description, unless otherwise specified, taking the injection device 9A Figure 2 and Figure 3 the injection device 9B as representatives, taking the structure of the injection device 9A as an example, in addition, the reference numerals of the injection device 9A are sometimes used. However, as long as there is no contradiction, etc., the description related to the injection device 9A can also be used for the injection device 9B.

[0088] (1. Structure of the Die Casting Machine)

[0089] Figure 1 is a side view including a cross-sectional view showing a part of the structure of the main part of the die casting machine 1 of the embodiment.

[0090] As described in the overview of the above injection device 9 (9A and 9B), the die casting machine 1 injects a liquid metal material (molten metal) into the mold 101. In a higher-level concept, the molten metal is a metal material (molding material) in an uncured state. The uncured state includes not only the liquid state but also the solid-liquid coexistence state. The solid-liquid coexistence state is a semi-solid state solidified from the liquid state or a semi-molten state melted from the solid state. The metal is, for example, aluminum or an aluminum alloy. It should be noted that in the description of the embodiment, the molten metal is basically taken as an example of the metal material in the uncured state.

[0091] The die 101 includes, for example, a stationary die 103 and a movable die 105. The main part of the space 107 for filling the molten liquid in the die 101 is formed between the stationary die 103 and the movable die 105. The stationary die 103 is a non-movable die. The movable die 105 is a die that moves in a direction (die opening and closing direction) opposite to the stationary die 103. The die opening and closing direction is, for example, a horizontal direction. In the description of the present embodiment, for convenience, a cross-section of the stationary die 103 or the movable die 105 is represented by a kind of shading, but these dies can be engraving type or nesting type. In addition, cores or the like can be combined in the stationary die 103 and the movable die 105.

[0092] The die casting machine 1 has, for example, a machine body 3 that performs mechanical actions for molding, a controller 5 that controls the actions of the machine body 3, and an interface 13 that establishes an association between the controller 5 and the operator.

[0093] In addition to the injection device 9 described above, the machine body 3 has, for example, a mold clamping device 7 that opens and closes and clamps the die 101, and an extrusion device 11 that extrudes the die casting from the stationary die 103 or the movable die 105 ( Figure 1 in this case, the movable die 105). In the machine body 3, the structures (for example, the structures of the mold clamping device 7 and the extrusion device 11) and their actions other than the injection device 9 can be set to various structures and actions, for example, known structures and actions. In addition, for the structures and actions that can be set to known structures and actions, the description is appropriately omitted.

[0094] During the molding cycle, the mold clamping device 7 moves the movable die 105 toward the stationary die 103 to perform die closing. Moreover, the mold clamping device 7 applies a mold clamping force corresponding to the elongation amount of a connecting rod (reference numeral omitted) to the die 101 to perform die closing. A space 107 is formed in the closed die 101. The injection device 9 injects and fills the molten liquid into the space 107. The molten liquid in the space 107 is deprived of heat by the die 101 and is cooled and solidified. That is, the molten liquid becomes a molded part. After that, the mold clamping device 7 moves the movable die 105 in a direction away from the stationary die 103 to perform die opening. At this time or later, the extrusion device 11 extrudes the molded part from the movable die 105.

[0095] The controller 5, although not particularly illustrated, may be configured to include a computer, for example. The computer may be configured to include a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and an external storage device, although not particularly illustrated. The CPU executes programs stored in the ROM and / or the external storage device, thereby constructing various functional units that perform various operations (including control). In addition, the controller 5 may include a logic circuit that performs certain actions, a power supply circuit, and a driver for conceptualization purposes.

[0096] The controller 5 may be provided, for example, in a control panel (not shown). In addition, a part of the controller 5 may be constituted by a part of the interface 13. The controller 5 may be concentrated in one place in terms of hardware or may be dispersed in multiple places. The controller 5 may be configured to include sub-controllers for the clamping device 7, the injection device 9, and the extrusion device 11, respectively, and a superordinate controller that performs control such as synchronization between the sub-controllers, or it may not be configured in this way.

[0097] Furthermore, when looking at each device included in the die casting machine 1, the controller 5 can be regarded as the controller of that device. For example, the controller 5 can be regarded as the controller of the injection device 9. The same applies to the interface 13. For example, the interface 13 can be regarded as a component of the injection device 9.

[0098] The interface 13 can be provided at an appropriate position. In the illustrated example, it is provided on the fixed platen (reference numeral omitted) of the clamping device 7. The interface 13 has an input device 15 that accepts input operations from an operator and a display device 17 that displays images. The display device 17 is constituted by, for example, a liquid crystal display screen or an organic EL display screen, and also constitutes a display portion of a touch panel. The input device 15 is constituted by, for example, a mechanical switch and the above-mentioned touch panel.

[0099] The control signals SG1 and SG2 ( Figure 2 and Figure 3 ) may be control signals output from the controller 5 in the concept of a driver (not shown) that does not include the first valve 39A and the second valve 39B to the above-mentioned driver, or may be control signals input from the controller 5 in the concept of a driver including the driver to the first valve 39A and the second valve 39B. In the description of the embodiments, for convenience, expressions that ignore the existence of the driver are sometimes used. Therefore, for example, even if it is expressed that the control signal SG1 is input to the first valve 39A, the control signal SG1 is not limited to being output from the driver to the first valve 39A, and may also be output from the controller 5 in the concept of a driver that does not include the driver to the driver.

[0100] (2. Structure of the injection device)

[0101] (2.1. Overall injection device)

[0102] As described above, the injection device 9 has a sleeve 21, a plunger 23, a coupling 25, an injection cylinder 27, and a hydraulic circuit 35A (or 35B). However, since the sleeve 21 and the plunger 23 can be regarded as consumables, only the injection cylinder 27 and the hydraulic circuit 35A (and the controller 5) can also be regarded as the injection device.

[0103] The sleeve 21 is, for example, a cylindrical member, and a supply port 21a for receiving the melt into the sleeve 21 is provided on the upper surface. The plunger 23 has, for example, a plunger head 23a that can slide in the front-rear direction within the sleeve 21 and a plunger rod 23b whose front end is fixed to the plunger head 23a.

[0104] If the mold 101 is closed by the mold clamping device 7, a melt of one injection amount is injected into the sleeve 21 from the supply port 21a through a melt supply device (not shown). Then, the plunger 23 slides forward within the sleeve 21 from the illustrated position, and thus the melt within the sleeve 21 is extruded (injected) into the mold 101.

[0105] (2.2. Injection cylinder)

[0106] In Figure 2 and Figure 3 In the illustrated injection cylinder 27, the shapes of the cross-sections of the interior of the cylinder member 29, the piston 31, and the piston rod 33 are, for example, circular. A gasket (not shown) may be interposed between the cylinder member 29 and the piston 31. It should be noted that even when a gasket is interposed, for convenience, it is shown that the piston 31 slides within the cylinder member 29.

[0107] The injection cylinder 27 can also be configured in various structures other than those shown. For example, although not particularly shown, the injection cylinder 27 can be configured as a supercharging type. In addition to the illustrated structure, the supercharging type injection cylinder has a supercharging cylinder communicating with the head side chamber 29h and a supercharging piston sliding within the supercharging cylinder. And, for example, the injection cylinder 27 can also be used for a hybrid drive unit that combines a hydraulic type and an electric type. In this case, the injection cylinder 27 (and / or the hydraulic circuit 35A) can, for example, also be configured to be able to contribute only to a part of the drive during the reciprocating stroke of the plunger 23.

[0108] (2.3. Hydraulic circuit)

[0109] In Figure 2 the hydraulic circuit 35A only illustrates the structure of the main part related to the forward movement of the piston 31. Therefore, for example, the structure for retracting the piston 31 and the structure for pressurizing the reservoir 41 described later are omitted from the illustration.

[0110] The hydraulic circuit 35A has, for example, a reservoir 41 as an example of a hydraulic source (supply source) that supplies the working fluid to the head-side chamber 29h, and an ACC valve 43 that permits / forbids the flow of the working fluid from the reservoir 41 to the head-side chamber 29h. The structure of the ACC valve 43 is arbitrary, and in Figure 2 it, a pilot-operated check valve is illustrated as an example.

[0111] In addition, the hydraulic circuit 35A has, for example, a tank 45 as an example of an object to which the working fluid from the rod-side chamber 29r is discharged. The tank 45 is, for example, of the atmosphere-open type and keeps the working fluid substantially at atmospheric pressure. As described above, the flow rate of the working fluid from the rod-side chamber 29r to the tank 45 is controlled by the orifice-outlet circuit 37A.

[0112] Furthermore, although not particularly illustrated, the hydraulic circuit 35A (35B) may also have a circulation circuit that returns the working fluid in the rod-side chamber 29r to the head-side chamber 29h (another example of a discharge object) when the piston 31 advances. The orifice-outlet circuit 37A can control not only the flow rate from the rod-side chamber 29r to the tank 45 but also the flow rate of the circulation circuit, or can control the flow rate of the circulation circuit instead of controlling the flow rate from the rod-side chamber 29r to the tank 45.

[0113] Figure 3 The illustrated hydraulic circuit 35B has, for example, a rod-side valve 47 that permits / forbids the discharge of the working fluid from the rod-side chamber 29r instead of the orifice-outlet circuit 37A of the hydraulic circuit 35A. The structure of the rod-side valve 47 is arbitrary, and in Figure 3 it, a pilot-operated check valve is illustrated as an example.

[0114] In the hydraulic circuit 35B, for example, in the same manner as the hydraulic circuit 35A, the working fluid is supplied from a reservoir 41 as an example of a hydraulic source to the head-side chamber 29h. However, in the hydraulic circuit 35B, the flow rate of this working fluid is controlled by the orifice-inlet circuit 37B as described above. It should be noted that although not particularly illustrated, in the hydraulic circuits 35A and 35B, the head-side chamber 29h may also be supplied with the working fluid from a pump as another example of a hydraulic source. The orifice-inlet circuit 37B can control not only the flow rate from the accumulator 41 to the head-side chamber 29h but also the flow rate from the pump to the head-side chamber 29h, or can control the flow rate from the pump to the head-side chamber 29h instead of controlling the flow rate from the accumulator 41 to the head-side chamber 29h.

[0115] Although not particularly illustrated, the outlet throttling circuit 37A may also have three or more flow control valves (such as the first valve 39A, etc.). The same applies to the inlet throttling circuit 37B. In addition, the injection device 9 may also be different from the illustrated example and have both an outlet throttling circuit (37A) and an inlet throttling circuit (37B). In a mode where both an outlet throttling circuit and an inlet throttling circuit are provided, only one of the circuits may have two or more flow control valves, and the other circuit may have only one flow control valve, or both circuits may each have two or more flow control valves.

[0116] In addition, the outlet throttling circuit 37A can be used as an inlet throttling circuit when the piston 31 retracts, or it may not be used as an inlet throttling circuit. Similarly, the inlet throttling circuit 37B can be used as an outlet throttling circuit when the piston 31 retracts, or it may not be used as an outlet throttling circuit. In the description of the embodiment, unless otherwise specified, only the forward movement of the piston 31 is considered, and the terms of outlet throttling and inlet throttling are used.

[0117] (2.4. Flow control valve)

[0118] The structures of the first valve 39A and the second valve 39B can be set to various structures as long as they can control the flow rate, for example, they can be set to known structures. For example, these valves may or may not be servo valves. A servo valve, for example, performs closed-loop control based on the detected value of the position of the valve body (the component that opens and closes the interface of the valve) through a servo driver not shown, and adjusts the flow rate steplessly according to the input signal (makes the flow rate an arbitrary value). In addition, the first valve 39A and the second valve 39B may or may not be flow regulating valves with pressure compensation. A flow regulating valve with pressure compensation maintains the flow rate at a set value regardless of pressure fluctuations. In addition, for example, the valve bodies of the first valve 39A and the second valve 39B can be spool valves, or they can be disk-shaped, needle-shaped, or spherical valve bodies. In addition, for example, the driving methods of the first valve 39A and the second valve 39B can be electromagnetic, or they can be a combination of electromagnetic and pilot types.

[0119] The structures (constructions and / or dimensions, etc.) and / or performances of the first valve 39A and the second valve 39B can be the same as or different from each other. As the performance of the valve, for example, the flow rate when the opening is maximum (maximum flow rate) and the change in the flow rate with respect to the change in the opening (the capacity coefficient in another view) (flow rate characteristics) can be cited. It should be noted that in the description of the embodiment, unless otherwise specified, sometimes the description is based on the premise that the structures of the two valves are the same as each other, and further, the performances of both are the same as each other.

[0120] As described above, the first valve 39A and the second valve 39B are connected in parallel with each other. For example, the two valves are as Figure 3As shown, the flow paths connected to the inlets of the respective valves merge with each other, and further, the flow paths connected to the outlets of the respective valves merge with each other. Further, regarding Figure 2 the connection of the rod-side chamber 29r in Figure 2 to the valve, as shown, two valves can be connected in parallel to each other by being respectively communicated with the same cylinder chamber (the rod-side chamber 29r in the illustrated example). In the above, the term of the same cylinder chamber can be replaced with the term of the same hydraulic source (e.g., the accumulator 41) or the same discharge object (e.g., the tank 45).

[0121] In another view, the manner in which two valves are described as being connected in parallel does not include a manner in which the cylinder chambers, hydraulic sources, or discharge objects connected to the inlets or outlets of the two valves are not the same. For example, the valve between the syringe reservoir and the head-side chamber 29h and the valve between the booster reservoir and the head-side chamber 29h are not two valves connected in parallel because the hydraulic sources are not the same.

[0122] (2.5. Sensor)

[0123] The injection device 9 can be provided with various sensors in order to grasp the operation of each part. The controller 5 controls each part of the injection device 9 (the die-casting machine 1 in another view) based on the detection values of the various sensors. The various sensors can be provided in the same manner as known sensors. In Figure 2 this, an example of the position sensor 49 that detects the position of the plunger 23 is illustrated. Although not particularly shown, as other sensors, for example, a pressure sensor for detecting the pressure of the head-side chamber 29h (the pressure applied by the plunger 23 to the melt in another view) and a pressure sensor for detecting the pressure of the accumulator 41 can be cited.

[0124] The structure of the position sensor 49 can be set to various structures, for example, it can be set to a known structure. More specifically, for example, the position sensor 49 can be a magnetic or optical linear encoder, or a laser rangefinder. Further, as is well known, velocity is obtained by differentiating the position, and acceleration is obtained by differentiating the velocity. Conversely, velocity is obtained by integrating the acceleration, and position is obtained by integrating the velocity. Therefore, the position sensor 49 can be regarded as a velocity sensor or an acceleration sensor. In addition, the structure of the position sensor 49 can generally also be regarded as a velocity sensor or an acceleration sensor.

[0125] (3. Operation of the Injection Device)

[0126] Figure 4This is a schematic diagram showing an example of the operation of the injection device 9. In this diagram, the horizontal axis represents time t, and the vertical axis represents the injection speed V, the injection pressure P, and the position D of the plunger 23. The injection speed V is the speed of the plunger 23. The injection pressure P is the pressure applied by the plunger 23 to the melt. Here, the position D is the position of the plunger 23 based on the position at the start of injection (time t0), and in another view, it is the moving distance D of the plunger 23 from the start of injection, and further is the integral value of the injection speed V. In the figure, the line Ln1 represents the change over time of the injection speed V, the line Ln2 represents the change over time of the injection pressure P, and the line Ln3 represents the change over time of the position D.

[0127] The injection device 9, for example, generally performs low-speed injection (roughly from t0 to t2), high-speed injection (roughly from t2 to t3), and pressure boosting (pressure increase, roughly from t3 or t4 to the end) in sequence. The operations of these processes are as follows, for example.

[0128] (3.1. Low-speed injection)

[0129] When the specified injection start condition is satisfied, the controller 5 starts the forward movement of the plunger 23 (time t0), causing the plunger 23 to advance at a low-speed injection speed V with a relatively low speed L (from time t1 to t2). Thereby, the entrainment of air by the melt is suppressed, and the melt in the sleeve 21 is extruded toward the space 107. The low-speed injection speed V L can be set appropriately, for example, less than 1 m / s. Usually, it is often about 0.2 - 0.3 m / s, and sometimes it is set to about 0.1 m / s. In addition, the low-speed injection speed V L is, for example, a constant value. However, appropriate variable speed control can also be performed. During low-speed injection, since the injection speed is low, the injection pressure becomes a relatively low pressure (low-speed injection pressure P L ).

[0130] To perform the above operations, the controller 5, for example, supplies the working fluid from the reservoir 41 to the head-side chamber 29h and allows the working fluid to be discharged from the rod-side chamber 29r. The speed of the plunger 23 is controlled by the outlet throttle circuit 37A and / or the inlet throttle circuit 37B.

[0131] (3.2. High-speed injection)

[0132] When the plunger 23 reaches the specified high-speed switching position (time t2), the controller 5 causes the plunger 23 to advance at a high-speed injection speed V with a relatively high speed H Thereby, for example, the melt is quickly filled into the space 107 before the melt solidifies. The high-speed injection speed V H can be set appropriately, for example, 1 m / s or more. The high-speed injection speed V HFor example, it is a constant value. However, appropriate variable speed control can also be performed. During high-speed injection, since the injection speed is high, the injection pressure becomes a high-speed injection pressure P that is higher than the low-speed injection pressure P L higher than the high-speed injection pressure P H .

[0133] To perform the above-described operations, specifically, the controller 5, for example, continues to supply the working fluid from the accumulator 41 to the head-side chamber 13h after low-speed injection, and increases the flow rate controlled by the outlet throttle circuit 37A and / or the inlet throttle circuit 37B.

[0134] (3.3. Boosting and holding pressure)

[0135] As a result of high-speed injection, when the molten fluid substantially fills the space 107 (at time t3), there is nowhere for the molten fluid to go, so the pressure of the molten fluid rises and the plunger 23 decelerates. In addition, deceleration control for reducing the flow rate controlled by the outlet throttle circuit 37 and / or the inlet throttle circuit 37B can also be performed at an appropriate time.

[0136] After that, the plunger 23 (substantially) stops (at time t4), and the pressure of the molten fluid rises to reach the casting pressure (final pressure) (boosting process). Then, the casting pressure is maintained (holding pressure process). Either a special operation for boosting can be performed or not (it can also be that the molten fluid has nowhere to go and the pressure rises). As an example of the former, for example, a method can be cited as follows: speed control is performed before the start of boosting, and in contrast, pressure control is performed during boosting. In addition, a method can be cited in which the accumulator that supplies the working fluid to the head-side chamber 29h during boosting is different from the accumulator before the start of boosting, and a method in which the working fluid is supplied to the boosting cylinder to perform boosting.

[0137] The first valve 39A and the second valve 39B contribute not only to speed control but also to the pressure control described in the previous paragraph. In this pressure control, the first valve 39A and the second valve 39B, for example, can also be input with different control signals, controlled according to different algorithms, and / or perform different operations.

[0138] If holding pressure is performed and the molten fluid solidifies, the mold clamping device 7 is opened, the die-cast part of the extrusion device 11 is extruded from the mold (in the Figure 1 example, it is the fixed mold 103), and the plunger 23 is retracted, etc.

[0139] (3.4. Other operations)

[0140] The operation of the injection device 9 can be associated with Figure 4The actions shown are different. For example, the injection device 9 can perform laminar filling with low-speed injection. In other words, high-speed injection may not be performed. Additionally, in a hybrid type combining hydraulic and electric types, the injection cylinder 27 can also be responsible for only one or two of the three processes of low-speed injection, high-speed injection, and pressure boosting. In this case, the first valve 39A and the second valve 39B can also be used only in the above one or two processes.

[0141] (4. Operation of the flow control valve)

[0142] As described above, the first valve 39A and the second valve 39B are input with different control signals during at least a part of the same molding cycle, are controlled according to different algorithms, and / or perform different actions. Such specific ways of control and / or action can be various, and the effects achieved are also various. Examples are illustrated below.

[0143] (4.1. First and second operation examples)

[0144] Figure 5 FIG. is a diagram showing first and second operation examples of the first valve 39A and the second valve 39B.

[0145] In Figure 5 the upper diagram corresponds to Figure 4 a part of. Specifically, the upper diagram extracts Figure 4 the part immediately after the start of injection in the time variation of the injection speed (speed V, line Ln1) shown. In addition, the notations of time t0 and t1 are marked on the horizontal axis t of the lower diagram described later.

[0146] In Figure 5 the middle diagram shows a first operation example of the two valves (39A and 39B) for achieving the injection speed shown in the upper diagram. The lower diagram shows a second operation example of the two valves (39A and 39B) for achieving the injection speed shown in the upper diagram. In the middle and lower diagrams, the horizontal axis is the same time t as in the upper diagram, and the scales are consistent. In addition, in the middle and lower diagrams, the vertical axis represents the signal level Sv of the control signal (for example, voltage). The broken line depicted within the range defined by the horizontal and vertical axes represents the time variation of the signal level Sv of the control signal SG1 input to the first valve 39A and the control signal SG2 input to the second valve 39B.

[0147] The relationship between the signal level Sv and the valve opening is arbitrary. Here, for convenience, the larger the signal level Sv (the further it travels upward along the vertical axis), the larger the valve opening, and the two are in a proportional relationship. Therefore, the vertical axis can also be regarded as the valve opening.

[0148] In either the first operation example (the middle figure) or the second operation example (the lower figure), the controller 5 only opens one of the valves (the first valve 39A in the illustrated example) at the start of injection. Then, the controller 5 opens the other valve (the second valve 39B in the illustrated example) to make both valves open (to make the two valves in a cooperative state).

[0149] By such an operation, for example, the accuracy of the injection speed can be improved. The reason is as follows, for example.

[0150] Figure 6 It is a diagram for explaining an example of the effects of the first and second operation examples.

[0151] In Figure 6 the two left-side figures (the upper-left figure and the lower-left figure) show the actions of the comparative example, and the two right-side figures (the upper-right figure and the lower-right figure) show the actions of the embodiment.

[0152] In the upper-left figure, the curve graph marked with "A" shows the action of the first valve 39A, the curve graph marked with "B" shows the action of the second valve 39B, and the curve graph marked with "A + B" shows the action of both valves (39A and 39B). In these curve graphs, the horizontal axis represents the opening degree L of one valve. The vertical axis represents the injection speed V. The upper-left figure has been explained, but the upper-right figure is the same.

[0153] In addition, in Figure 6 as the flow characteristics of each valve, it is assumed that if the opening degree becomes larger, the slope of the change in the injection speed V (the flow rate in other viewpoints) with respect to the change in the opening degree becomes larger (equal percentage characteristic (or a characteristic similar thereto. The same applies hereinafter)). However, for other flow characteristics, the explanations herein can also be appropriately applied.

[0154] In the upper-left figure, ΔL is the minimum controllable change amount (resolution) of the opening degree of each valve. Here, different from this embodiment, for example, consider the case of controlling the two valves by inputting the same control signal to the two valves. At this time, the two valves open simultaneously with the same opening degree for each other. Therefore, the minimum controllable change amount (resolution) in the injection speed V (A + B) controlled by the two valves becomes the ΔV obtained by adding the change amounts of the injection speed V when changing the opening degree of each valve by ΔL 1 (exceeding V 1 it is ΔV when 2 ).

[0155] On the other hand, in the present embodiment, only one of the two valves is opened, or both are opened. Thus, as shown in the upper right figure, the resolution of the injection speed V (the change in speed corresponding to ΔL) becomes the change in the injection speed V, i.e., ΔV, when the opening degree of one valve changes by ΔL 1 ’ (< ΔV 1 ). In addition, using the aforementioned equal percentage characteristics, between V 1 ’ and V 2 ’, it is possible to achieve the resolution of ΔV 1 ’ with respect to the magnitude between ΔV 2 . 2 ’

[0156] The lower left figure is a diagram showing the change over time of the injection speed when the injection speed V proportional to the passage of time t is achieved by the resolution shown in the curve graph of “A + B” in the upper left figure. The horizontal axis represents the time t, and the vertical axis represents the injection speed V. The line Ln11 represents the target speed, and the line Ln12 represents the achieved speed (the theoretical value ignoring control delay, etc.). As shown in this figure, due to the limitation of the resolution, the achieved speed becomes step-like with respect to the target speed, and the size of this step becomes the resolution ΔV 1 (or ΔV 2 ).

[0157] The lower right figure is the same as the lower left figure corresponding to the curve graph of “A + B” in the upper right figure. As shown in this figure, in the embodiment, the resolution is smaller than that in the comparative example. As a result, the step difference of the achieved speed also becomes smaller. Furthermore, the achieved speed approaches the target speed. That is, the control accuracy is improved.

[0158] Return Figure 5 , as described above, after starting the injection by opening one valve (39A) of the first valve 39A and the second valve 39B, the other valve (39B) is also opened. Thus, for example, the valve body of the other valve can pass through the dead zone where flow is not allowed even if the valve body moves, or an interval where it is difficult to obtain the intended flow characteristics with respect to the movement of the valve body. As a result, for example, in subsequent processes (such as high-speed injection), the responsiveness when controlling the injection speed by both valves can be improved.

[0159] In the same molding cycle, the specific manner of the operation of opening the other valve after opening one valve can be various.

[0160] For example, after both valves are opened, the signal level Sv of the control signal input to the two valves, the algorithm for controlling the two valves, and / or the operations of the two valves (such as the opening degree and / or the flow rate) can be the same as or different from each other. In Figure 5In the example, the opening degree of the first valve 39A (the valve that is opened first in another view) is larger than that of the second valve 39B. However, the relationship between the opening degrees of the two can also be reversed, or the opening degrees of the two can be the same.

[0161] In addition, for example, the timing of opening the second valve 39B (the valve that is opened later) is arbitrary. In the first operation example ( Figure 5 in the middle part), the second valve 39B is opened midway through the acceleration of the injection speed V (after time t0 and before time t1). In the second operation example ( Figure 5 in the lower part), the second valve 39B is opened at a time after the acceleration of the injection speed V ends (after time t1, which can also be regarded as after the end). In the second operation example, the end period of the period for setting the timing of opening the second valve 39B can be set. In the extreme case, if it is within one molding cycle (in other words, before the next time t0), there is no particular limitation. In Figure 5 the example in the lower part, the timing when the second valve 39B is opened is set during low-speed injection (assuming the example of Figure 4 is high-speed injection before).

[0162] As in the first operation example, when the second valve 39B is opened during acceleration, since both valves become the opening degree of the low-speed injection speed V after acceleration, the transition to the next operation becomes smooth. In addition, when the second valve 39B is opened after acceleration (or after the acceleration) as in the second operation example, the stability of the control in the interval before confluence (here is the acceleration interval to the low-speed injection speed V) is high. L In the case where the second valve 39B is opened during acceleration as in the first operation example, since both valves become the opening degree of the low-speed injection speed V after acceleration, the transition to the next operation becomes smooth. In addition, when the second valve 39B is opened after acceleration (or after the acceleration) as in the second operation example, the stability of the control in the interval before confluence (here is the acceleration interval to the low-speed injection speed V) is high. L In the case where the second valve 39B is opened during acceleration as in the first operation example, since both valves become the opening degree of the low-speed injection speed V after acceleration, the transition to the next operation becomes smooth. In addition, when the second valve 39B is opened after acceleration (or after the acceleration) as in the second operation example, the stability of the control in the interval before confluence (here is the acceleration interval to the low-speed injection speed V) is high.

[0163] (4.2. Third and Fourth Operation Examples)

[0164] Figure 7 is a diagram for explaining the third operation example of the first valve 39A and the second valve 39B. In Figure 7 the upper part of the figure is the same as the upper part of the figure in Figure 5 and is a part of Figure 4 . Among them, Figure 4 and Figure 5 are diagrams assuming that the target speed is the same as the actual speed (the detected speed in another view), but Figure 7 respectively represent the target speed (line Ln1a) and the actual speed (line Ln1b). In addition, this actual speed is not the speed obtained through the third operation example, but the speed obtained through other operation examples (such as previous operations).

[0165] As in Figure 7As shown in the upper figure, the actual speed is delayed with respect to the target speed, for example, at the initial stage of acceleration. As a reason for this, for example, it can be cited that due to the compressibility of the working fluid, the operation of the injection cylinder 27 is delayed with respect to the operation of the valve. In addition, in the equal percentage characteristics described above, it can be cited that the flow rate is difficult to increase when the opening degree is small.

[0166] In addition, after acceleration, an overshoot occurs where the actual speed exceeds the target speed. As a reason for this, for example, it can be cited that in the case of performing closed-loop control (for example, PID (Proportional-Integral-Differential) control) based on the detected value of the injection speed V, the effect of the operation amount corresponding to the large deviation between the initial target speed and the detected speed during acceleration takes effect after acceleration.

[0167] In addition, although not particularly shown, the injection speed V also varies due to disturbances. As disturbances, for example, it can be cited that the pressure variation received by the plunger 23 from the molten liquid, the variation of the sliding resistance between the plunger 23 and the sleeve 21, and the pressure variation of the working fluid caused by the compressibility or pressure wave of the working fluid.

[0168] Therefore, different from this embodiment, if it is desired to solve the above problems with only one flow control valve (39A or 39B), for example, it is necessary to switch the algorithm or adjust the gain according to the control period and / or the state of the deviation (frequency or mode, etc.), and the control becomes complicated. Therefore, for example, the first valve 39A and the second valve 39B can be controlled as follows.

[0169] Figure 7 The middle and lower figures of are respectively the same figures as Figure 5 a part of the middle figure of. Figure 7 The middle figure of shows the temporal change of the signal level Sv of the control signal SG1 input to the first valve 39A. Figure 7 The lower figure of shows the temporal change of the signal level Sv of the control signal SG2 input to the second valve 39B.

[0170] The control signal SG1 whose signal level Sv changes according to the change of the target speed is mainly input to the first valve 39A. Specifically, corresponding to the gradual increase of the target speed, the signal level Sv of the control signal SG1 gradually increases. The control signal SG1 can also compensate for the delay of the actual speed with respect to the target speed during acceleration (the characteristic that is the main cause). For example, the slope of the target speed (the change rate of the target speed with respect to the passage of time) is constant, and in contrast, the slope of the signal level Sv of the control signal SG1 can be set to the maximum immediately after the start of injection (time t0), and then gradually decrease.

[0171] On the other hand, a control signal SG2 whose input signal level Sv to the second valve 39B varies according to a factor different from the change in the target speed is mainly input. In another aspect, for example, the signal level Sv of the control signal SG2 does not change (or changes less) according to the change in the target speed. And / or, regarding the correlation between the target speed and the signal level Sv obtained by sampling all or a part of the molding cycle, the correlation of the control signal SG2 is smaller than that of the control signal SG1. And / or, regarding the proportional gain of the deviation of the opening degree (and / or flow rate) with respect to the speed, the control signal SG2 is smaller than the control signal SG1.

[0172] As the above-mentioned other factor that causes the control signal SG2 to change, for example, interference can be cited. However, in Figure 7 the illustration of the change in the signal level Sv of the control signal SG2 corresponding to the interference is omitted. Additionally, for example, the delay of the actual speed with respect to the target speed during the above acceleration can be cited. More specifically, in Figure 7 the example, the control signal SG2 temporarily increases the flow rate immediately after the start of injection (at time t0) (during the period before the acceleration completion time t1). Additionally, as the above-mentioned other factor, a pressure drop in the accumulator 41 can be cited (which can also be regarded as a type of interference). The pressure drop in the accumulator 41 occurs, for example, when supplying the working fluid to the injection cylinder 27 and can be predicted. In Figure 7 the example, the signal level Sv of the control signal SG2 gradually increases over time to compensate for the pressure drop. Furthermore, if described confirmatively, the control signal SG1, for example, does not have a change (or has a smaller change) corresponding to a part or all of such other factors (here, interference and pressure drop).

[0173] If the first valve 39A and the second valve 39B are controlled as described above, it is easy to avoid the control of each valve from becoming complicated. For example, in the control of the first valve 39A, interference can be ignored. And / or, it is not necessary to distinguish between normal deviation and deviation caused by interference. In the second valve 39B, for example, the flow characteristics can be ignored and only interference correction can be performed. Additionally, for example, when the second valve 39B helps to ensure the flow rate immediately after the start of injection, the acceleration at the initial stage of injection can be ensured even without increasing the proportional gain of the first valve 39A. As a result, the necessity of changing the gain, such as increasing the proportional gain of the first valve 39A at the initial stage of acceleration and then decreasing the proportional gain of the first valve 39A to avoid overly sensitive response to the deviation, is reduced.

[0174] In addition, in association with the above, it is also beneficial for adjusting the gains of the respective valves. For example, for the first valve 39A, open-loop control can be applied or the proportional gain can be made larger than that of the second valve 39B to ensure the acceleration of the injection speed V. Additionally, the differential gain can be set to a magnitude corresponding to the proportional gain (e.g., a magnitude effective for reducing overshoot). On the other hand, regarding the second valve 39B, it can be set to a magnitude suitable for external disturbances. That is, it is easy to set gains suitable for the functions of the first valve 39A and the second valve 39B. Moreover, as long as one of the first valve 39A and the second valve 39B is experimentally set to the closed state, the effect of controlling the other valve can be investigated. From this perspective, it is also beneficial for gain adjustment.

[0175] In addition, since the flow rate is ensured by the first valve 39A, the opening degree of the second valve 39B can be smaller. Therefore, from Figure 6 the description, in the case where the second valve 39B has an equal percentage characteristic, the second valve 39B is used at an opening degree with high resolution. As a result, the accuracy of controlling the injection speed V is improved.

[0176] Figure 8 It is a diagram showing a fourth operation example of the first valve 39A and the second valve 39B.

[0177] In Figure 8 the upper diagram shows the temporal changes of the target speed (line Ln1a) and the actual speed (line Ln1b) in the same way as the upper diagram of Figure 7 . However, Figure 8 it shows the temporal changes near the moment t2 when switching from low-speed injection to high-speed injection. Figure 8 The actual speed (line Ln1b) in Figure 8 is not the speed obtained by the fourth operation example, but the speed obtained by other operation examples (e.g., previous operations). Additionally, Figure 5 the lower diagram in

[0178] shows the temporal changes of the signal levels Sv of the control signal SG1 input to the first valve 39A and the control signal SG2 input to the second valve 39B in the same way as the middle or lower diagram of L The fourth operation example, like the third operation example, is an operation example during the acceleration period of the injection speed V. However, the fourth operation example is an operation example during the acceleration period from the low-speed injection speed V H to the high-speed injection speed V. The description of the third operation example can be appropriately applied to the fourth operation example as long as there are no contradictions, etc. If a summary is recorded for the sake of caution, it is as follows.

[0179] A control signal SG1 whose main input signal level Sv to the first valve 39A changes according to the change in the target speed is input. Additionally, the control signal SG1 can also compensate for the delay of the actual speed relative to the target speed during acceleration (characteristics, flow characteristics, etc. that are the main causes). On the other hand, a control signal SG2 whose main input signal level Sv to the second valve 39B changes according to factors other than the target speed is input. As other factors, external interference, characteristics (such as flow characteristics) that are the main causes of the delay during acceleration, and the decrease in the pressure of the accumulator can be cited. Moreover, as a result of such control, effects such as simplification of control, easier adjustment of gain, and improvement of resolution can be obtained.

[0180] In Figure 8 it is different from Figure 7 , the control signal SG2 omits the increase in the signal level Sv for compensating the decrease in the pressure of the accumulator 41. In addition, near just after the acceleration of the injection speed V is completed, the signal level Sv of the control signal SG2 decreases according to the interference. The operation before the time t2 can be the first operation example or the second operation example ( Figure 5 ), or can be the third operation example ( Figure 7 ).

[0181] (4.3. Fifth and sixth operation examples)

[0182] Figure 9 is a diagram showing the fifth operation example of the first valve 39A and the second valve 39B. In Figure 9 it, the upper diagram and the lower diagram show the temporal change of the signal level Sv of the control signal SG1 input to the first valve 39A and the control signal SG2 input to the second valve 39B in the same way as the middle diagram and the lower diagram of Figure 7 .

[0183] According to the times t0, t2, and t3 marked on the horizontal axis t, Figure 9 it shows the temporal change of the signal level Sv from the start of injection to the completion of high-speed injection. Regarding the temporal change of the injection speed V during this period, refer to Figure 4 .

[0184] In the fifth operation example, during low-speed injection (times t0 to t2), one of the two valves (the first valve 39A) is closed and the other (the second valve 39B) is open. Moreover, during high-speed injection (times t2 to t3), both valves are open. Thus, during low-speed injection, higher resolution and / or stable control are achieved through one valve, and during high-speed injection, a high injection speed V is obtained through a large flow rate HIt becomes easier. For example, the total flow rate of the two valves in high-speed injection is greater than the maximum flow rate of each valve (the flow rate at the maximum opening). In addition, the fifth operation example can also be regarded as applying the first and second operation examples in low-speed injection to high-speed injection. Therefore, as long as there are no contradictions, etc., the descriptions of the first and second operation examples can also be used for the fifth operation example.

[0185] Figure 10 is a diagram similar to that Figure 9 showing the sixth operation example of the first valve 39A and the second valve 39B.

[0186] Regarding the operation in low-speed injection, in the fifth operation example ( Figure 9 ), one of the two valves (the first valve 39A) is closed. In contrast, in the sixth operation example, the first valve 39A, like the second valve 39B in the third and fourth operation examples ( Figure 7 and Figure 8 ), controls the opening according to factors other than the change in the target speed (such as disturbances, etc.). Through such an operation, for example, in low-speed injection, the accuracy of controlling the injection speed V is improved, and in high-speed injection, it is easy to obtain a high injection speed V with a large flow rate H .

[0187] From another perspective, in the sixth operation example, the first valve 39A opens with an opening smaller than that of the second valve 39B during low-speed injection. In high-speed injection, the first valve 39A and the second valve 39B open with an opening larger than that of the second valve 39B during low-speed injection. As described in the explanation of the fifth operation example, the total flow rate of the two valves in high-speed injection can be greater than the maximum flow rate of each valve (the flow rate at the maximum opening), for example.

[0188] It can be understood from the descriptions in the previous two paragraphs that the description of the operation of the second valve 39B (the control signal SG2 in another perspective) in the third and fourth operation examples can be used for the operation of the first valve 39A (the control signal SG1 in another perspective) during low-speed injection in the sixth operation example. Illustrated in Figure 10 is the situation where during low-speed injection, as the pressure of the accumulator 41 drops, the control signal SG1 gradually increases.

[0189] In high-speed injection of the fifth and sixth operation examples, the openings (and / or flow rates) of the first valve 39A and the second valve 39B can be the same or different from each other. In addition, in the latter case, it can also be that either one is higher than the other. In addition, in high-speed injection, the functions of the two valves can be the same or different from each other.

[0190] Give an example of the latter. For example, the second valve 39B can contribute to speed control by performing closed-loop control (such as PID control) based on the detected value of the injection speed V from the start of injection to high-speed injection. On the other hand, the first valve 39A can be opened at an opening degree (for example, a preset constant opening degree) that fills the flow rate required to achieve the high-speed injection speed V during high-speed injection. In the case of a large filling amount, the movement amount of the valve body of the second valve 39B becomes smaller, and the responsiveness is improved. In addition, if the filling amount is adjusted according to the target speed, the function of the second valve 39B can be specialized to absorb external disturbances. H In the case of a large filling amount, the movement amount of the valve body of the second valve 39B becomes smaller, and the responsiveness is improved. In addition, if the filling amount is adjusted according to the target speed, the function of the second valve 39B can be specialized to absorb external disturbances.

[0191] In the fifth and sixth operation examples, the functions of the first valve 39A and the second valve 39B can also be switched between low-speed injection and high-speed injection. For example, regarding low-speed injection, it can be the same as the description so far. Regarding high-speed injection, contrary to the previous paragraph, the first valve 39A can be used for speed control based on closed-loop control, and the second valve 39B can be opened at an opening degree (for example, a constant opening degree) that fills the flow rate required for high-speed injection. The fifth and sixth operation examples can be combined with the first to fourth operation examples as long as there are no contradictions, etc.

[0192] (5. Specific examples of control of the flow control valve)

[0193] (5.1. Overall control)

[0194] According to the description so far, the first valve 39A and the second valve 39B are controlled so that the injection speed V approaches the target speed. This target speed is set, for example, as part of the casting conditions by the operator's operation on the input device 15. In addition, at least a part of the casting conditions including the target speed can also be set based on a signal input via communication from other devices. In the description of the embodiment, for convenience, without special explanation, the former example is used for explanation.

[0195] The target speed is set, for example, with respect to the position D of the plunger 23 (refer to Figure 4 ). Specifically, for example, the controller 5 receives the input of a plurality of positions D of the plunger 23 and the target speed at each position D. Then, the controller 5 generates and stores information (for convenience, referred to as the "first table") that establishes a correspondence between the plurality of positions D and the plurality of target speeds. The number of positions D for setting the target speed can be appropriately set by the operator, for example. In addition, the speed between one position D and the next position D can be determined by the controller 5 through appropriate interpolation calculations. The position range with a constant speed can be set, for example, by setting the same target speed at one position D and the next position D between these two positions D.

[0196] The controller 5, for example, converts the first table into a time series of the position D at every prescribed time scale. That is, the controller 5 calculates the target position that changes as time t elapses. Moreover, the controller 5 performs position control based on the above time series to achieve the target position updated at every moment with the above time scale, whereby the injection speed V is substantially controlled in terms of speed. Alternatively, the controller 5 can determine the target value of the current injection speed V based on the detected position D and the first table, and perform speed control to achieve this target value. In this way, the controller 5 can substantially perform speed control through position control, or directly perform speed control.

[0197] Therefore, in the following description of the control of the injection speed V (control of the flow control valve), the units of the control quantity, target value, and deviation can be the unit of the position D or the unit of the injection speed V. However, for the sake of convenience in explanation, unless otherwise specified, the injection speed V is used as the control quantity and target value.

[0198] As described above, the controller 5 can output mutually different control signals to the first valve 39A and the second valve 39B, and / or control these two valves according to mutually different algorithms. Therefore, as Figure 2 and Figure 3 shown, it can be considered that the controller 5 has a first control unit 5a for controlling the first valve 39A and a second control unit 5b for controlling the second valve 39B. In the following description, for the sake of convenience, the concepts of the first control unit 5a and the second control unit 5b are used. The first control unit 5a and the second control unit 5b can be physically separated from each other, can be the same as each other, or can share a part. In addition, the first control unit 5a and the second control unit 5b can be independent of each other in software, can be the same as each other, or can share a part.

[0199] The operations of the first valve 39A and the second valve 39B (for example, the first to sixth operation examples) described so far can be achieved by various control methods. Hereinafter, examples thereof will be sequentially described.

[0200] (5.2. An Example of a Flowchart)

[0201] Figure 11 is a flowchart showing an example of the order of processing executed by the controller 5 to achieve the first and second operation examples ( Figure 5 ). For example, every time the molding cycle is repeated, this processing is executed at the start of the molding cycle.

[0202] In step ST1, the controller 5 determines whether a prescribed injection start condition is satisfied. The injection start condition is, for example, obtaining information indicating that the mold clamping is completed and the melt is supplied to the barrel 21. Then, the controller 5 stands by in the case of a negative determination (repeating step ST1), and proceeds to step ST2 in the case of an affirmative determination.

[0203] In step ST2, the controller 5 opens the first valve 39A and starts outputting a control signal SG1 for adjusting the opening degree of the first valve 39A to an appropriate opening degree. Thereby, as described with reference to Figure 5 , injection starts at time t0 and the injection speed V is accelerated to the low injection speed V L .

[0204] In step ST3, the controller 5 determines whether a specified cooperation condition is satisfied. Then, when the determination is negative, the controller 5 stands by (repeats step ST3), and when the determination is positive, it proceeds to step ST4.

[0205] In step ST4, the controller 5 opens the second valve 39B and starts outputting a control signal SG2 for adjusting the opening degree of the second valve 39B to an appropriate opening degree. Thereby, as described with reference to Figure 5 , the first valve 39A and the second valve 39B cooperate at an appropriate time after the start of the acceleration of the injection speed V.

[0206] The cooperation condition in step ST3 can be set to an appropriate condition to achieve the intended operation. For example, the cooperation condition can be set such that the elapsed time (t) from the start of injection reaches a specified time, the detected speed of the injection speed V reaches a specified speed, or the position D reaches a specified position. According to the first operation example and the second operation example, the specified time can be, for example, a time before time t1 (first operation example) or a time at time t1 or after time t1 (second operation example). The same applies to the specified speed and the specified position.

[0207] In addition, the cooperation condition can be set by the manufacturer of the injection device 9 or can be set by the operator via the input device 15 or the like. In addition, the cooperation condition can also be set by the controller 5 based on casting conditions (such as the target speed of the injection speed V) or the like.

[0208] According to Figure 11 the flowchart, examples of sequences for implementing operations other than the first and second operation examples can be analogized.

[0209] For example, the fifth operation example ( Figure 9) It can be achieved by reversing the terms of the "first valve" and "second valve" in steps ST2 and ST4 and setting the cooperation condition to a high-speed switching condition that switches from low-speed injection to high-speed injection. The high-speed switching condition can be the same as that in conventional injection devices. For example, the high-speed switching condition can be set such that the detected position of the plunger 23 reaches the high-speed switching position set by the operator. And, for example, as described above, in the case of achieving the target position at all times, it can also be set such that the elapsed time since the start of injection reaches a specified time (t2).

[0210] In addition, for example, in the steps described in the previous paragraph, if the start of the interference control of the first valve 39A is added in step ST2 and step ST4 is set to the control of the first valve 39A for flow filling, the sixth operation example can be achieved ( Figure 10 ).

[0211] (5.3. First Structural Example of Control System)

[0212] Figure 12 It is a schematic diagram showing the first structural example of the control system of the injection device 9. It should be noted that the first structural example can be established throughout one molding cycle or during a part of one molding cycle. The same applies to the second structural example described later.

[0213] In the first structural example, the first control unit 5a controls the first valve 39A by open-loop control. On the other hand, the second control unit 5b controls the second valve 39B by closed-loop control (such as PID control) based on the detection value of the position sensor 49 (which can be either position or speed as described above). In addition, contrary to the example shown in the figure, the first control unit 5a can perform closed-loop control and the second control unit 5b can perform open-loop control.

[0214] Through the first structural example, for example, the third operation example and the fourth operation example can be achieved ( Figure 7 and Figure 8)。More specifically, for example, for the first valve 39A, a target value of the opening corresponding to a speed that is a certain amount lower than the target speed of the injection speed V is preset (the flow characteristics may also be considered), and open-loop control is performed in such a way as to achieve this target value. Thus, the first valve 39A mainly realizes the change in the opening (flow rate) corresponding to the change in the target speed. On the other hand, for the second valve 39B, closed-loop control (such as PID control) is performed in such a way that the deviation of the injection speed V (the difference between the target speed and the detected speed) becomes the above-mentioned certain amount. Thus, the second valve 39B mainly realizes the change in the opening (flow rate) corresponding to the disturbance. In addition, for the first valve 39A, a speed that is a certain amount lower than the target speed is used instead of the target speed, and for the second valve 39B, the deviation is set to the above-mentioned certain amount instead of 0, in order to make the flow rate of the second valve 39B greater than 0 even when the detected speed is consistent with the target speed, and to be able to reduce the flow rate of the second valve 39B to absorb the disturbance when the detected speed exceeds the target speed due to the disturbance.

[0215] And, through the first structural example, for example, the fifth operation example can be realized ( Figure 9 )。More specifically, for example, for the first valve 39A, open-loop control is performed to close at low-speed injection and make the opening a certain size at high-speed injection. On the other hand, for the second valve 39B, from the start of injection (or the end of acceleration just after the start of injection) to the end of high-speed injection, closed-loop control (such as PID control) based on the detected value of the position sensor 49 is performed.

[0216] Similarly, the sixth operation example can be realized through the first structural example ( Figure 10 )。More specifically, for example, for the first valve 39A, during low-speed injection, it gradually opens with a preset opening according to the decrease in the pressure of the accumulator, and during high-speed injection, open-loop control with the opening set to a certain size is performed. On the other hand, for the second valve 39B, closed-loop control is performed in the same manner as in the previous paragraph. However, during low-speed injection, as in the case of realizing the above-mentioned third and fourth operation examples (however, the functions of the first valve 39A and the second valve 39B are opposite), the first valve 39A can be closed-loop controlled to mainly correspond to the disturbance, and the second valve 39B can be open-loop controlled to mainly correspond to the target speed.

[0217] (5.4. Second Structural Example of the Control System)

[0218] Figure 13It is a schematic diagram showing a second structural example of the control system of the injection device 9. In the second structural example, both the first control unit 5a and the second control unit 5b perform closed-loop control based on the detection value of the position sensor 49 (which can be either position or speed as described above). However, the specific methods of the first control unit 5a and the second control unit 5b are different from each other. Thus, for example, the third operation example and the fourth operation example ( Figure 7 and Figure 8 ) are achieved. The specific methods can be various. Hereinafter, specific methods will be exemplified.

[0219] (5.4.1. First specific example of the second configuration example)

[0220] Figure 14 It is a schematic diagram showing a first specific example of the second structural example. As can be understood from the above-described explanations related to the controller 5, the various functional units shown in the figure can be implemented either by software or by hardware. This also applies to other specific examples.

[0221] In the first specific example, the first control unit 5a performs PID control (or a control similar thereto, the same hereinafter). On the other hand, the second control unit 5b does not perform PI control but only performs D control. Specifically, as described below.

[0222] In the controller 5, the comparison unit 51 calculates the difference (deviation) between the target value (which can be either position or speed as described above) and the detection value from the position sensor 49. The calculated deviation is integrated by the integration unit 53 and differentiated by the differentiation unit 55.

[0223] The first control unit 5a adds the value obtained by multiplying the deviation itself by the proportional gain Kp1, the value obtained by multiplying the integral value of the deviation by the integral gain Ki1, and the value obtained by multiplying the differential value of the deviation by the differential gain Kd1. Then, the first control unit 5a outputs the control signal SG1 based on the added value to the first valve 39A.

[0224] The second control unit 5b calculates the value obtained by multiplying the differential value of the deviation by the differential gain Kd2. Then, the second control unit 5b outputs the control signal SG2 based on the calculated value to the second valve 39B.

[0225] In the first structural example, only the first valve 39A performs closed-loop control based on the deviation itself. As a result, the control of the flow rate corresponding to the change in the target speed is basically performed by the first valve 39A. On the other hand, since closed-loop control based on the differentiation of the deviation is also performed on the second valve 39B, the second valve 39B helps to reduce overshoot and absorb external disturbances together with the first valve 39A.

[0226] Thus, for example, the third operation example and the fourth operation example (Figure 7 and Figure 8 )。And, for example, implement the sixth operation example ( Figure 10 ) for low-speed injection.

[0227] Various gains can be set appropriately. For example, the proportional gain Kp1 and the integral gain Ki1 can be set in the same way as in the prior art where there is only one flow control valve. The derivative gains Kd1 and Kd2 can be the same or different from each other. In the latter case, either one can be larger than the other. The derivative gains Kd1 and Kd2 can be set to appropriate values considering the target value of the injection speed V, the flow characteristics of these valves, and possible disturbances, etc. In addition, when comparing the gains as described above, as long as there is no special description and no contradiction, etc., it can be considered that the structures of the two valves are the same, or the values obtained by converting the gains in such a way that the gains are regarded as the same at the same opening and / or flow rate with respect to the same deviation are compared.

[0228] The derivative gain Kd1 can be less than the derivative gain Kd2, for example. Thus, for example, when the first valve 39A has an equal percentage characteristic, when the first valve 39A is opened at a certain size after acceleration, the probability that the first valve 39A reacts overly sensitively to disturbances due to low control resolution is reduced. On the other hand, the overshoot just after acceleration is also reduced by the second valve 39B, and after acceleration, external disturbances are absorbed by the second valve 39B with a smaller opening and higher control resolution.

[0229] (5.4.2. The second specific example of the second structural example)

[0230] Figure 15 It is a schematic diagram showing the second specific example of the second structural example. In the second specific example, the first control unit 5a performs PI control instead of PID control. In the first specific example, it has been described that the derivative gain Kd1 can be less than the derivative gain Kd2. The second specific example is equivalent to an example where the derivative gain Kd1 is further reduced, so as long as there is no contradiction, etc., the description of the first specific example can be followed.

[0231] (5.4.3. The third specific example of the second structural example)

[0232] Figure 16 It is a schematic diagram showing the third specific example of the second structural example. In the third specific example, not only does the first control unit 5a perform PID control, but the second control unit 5b also performs PID control. However, the values of various gains of the two are different from each other, and thus, different operations can be performed.

[0233] For example, as understood from the first specific example and the second specific example, the proportional gain Kp1 can be made greater than the proportional gain Kp2, and the derivative gain Kd1 can be made less than the derivative gain Kd2. In this case, for example, the effect brought about by the derivative gain Kd1 being less than the derivative gain Kd2 described in the description of the first specific example can be obtained. On the other hand, the second valve 39B also contributes to achieving a change in flow rate corresponding to a change in the target speed through the proportional gain Kp2, so it is easy for the flow rate to increase sharply or to ensure a large flow rate.

[0234] The second control unit 5b performs I control, so it helps to reduce the steady-state error. Therefore, for example, the second valve 39B can perform compensation for the pressure drop of the accumulator 41 illustrated in the third operation example ( Figure 7 ). In addition, the pressure reduction of the accumulator 41 can be predicted, so it can also be achieved by open-loop control.

[0235] In addition, the integral gains Ki1 and Ki2 can be the same as each other or different, and either one can be greater than the other. For example, when the proportional gain Kp1 is greater than the proportional gain Kp2, the integral gain Ki1 can be less than the integral gain Ki2. In this case, the effect is the same as when the derivative gain Kd1 is set to be less than the derivative gain Kd2. For example, the possibility of performing integral control with an opening degree having a low resolution in the control of the first valve 39A due to the equal percentage characteristic is reduced, and the control accuracy is improved.

[0236] (5.5. Another configuration example)

[0237] Although not particularly illustrated, the first control unit 5a and the second control unit 5b can also perform open-loop control during at least a part of one molding cycle.

[0238] For example, in the first operation example and the second operation example ( Figure 5 ), during the period from when the first valve 39A is opened until the opening degree of the second valve 39B to be opened next becomes a specified opening degree, both the first valve 39A and the second valve 39B can be controlled by open-loop control. Thereby, for example, a situation where the dead zone or the interval with poor characteristics affects the closed-loop control can be avoided.

[0239] In addition, for example, during at least the initial stage of the acceleration period (time t0 to t1) in the third operation example ( Figure 7 ) and the acceleration period (time t2 to t2’) in the fourth operation example ( Figure 8 ), both valves can be controlled by open-loop control. Thereby, for example, at the initial stage of the acceleration period, an opening degree larger than the opening degree obtained by closed-loop control can be achieved, so as to achieve a large acceleration. Of course, during the above-mentioned respective periods, one valve or both valves can also be controlled by closed-loop control.

[0240] In the second structural example in which closed-loop control is performed by both the first control unit 5a and the second control unit 5b, as understood from the first to third specific examples, the first control unit 5a and / or the second control unit 5b may perform only a part of the PID control or may perform all of the PID control. In addition, regarding a part or all of the P control, I control, and D control, the first control unit 5a and the second control unit 5b may overlap or may not overlap. In the case of overlap, parameters such as their gains may be the same as each other or may be different from each other.

[0241] In the second structural example, regarding the sharing of the P control, I control, and D control, various sharing methods can be performed in addition to the illustrated example. Specifically, for example, it may be that the first control unit 5a performs PID control, while the second control unit 5b performs PD control, PI control, ID control, or I control. In addition, it may be that the first control unit 5a performs PI control, while the second control unit 5b performs PD control or ID control. In addition, it may be that the first control unit 5a performs PD control, while the second control unit 5b performs I control. In this paragraph, the terms of the first control unit 5a and the terms of the second control unit 5b may also be interchanged.

[0242] Different from the description so far, the first control unit 5a and the second control unit 5b may also perform control independently of each other according to the same algorithm. For example, in the third specific example of the second structural example ( Figure 16 ), the values of various gains may also be the same in the first control unit 5a and the second control unit 5b. Even in this case, for example, in a mode in which a secondary loop of closed-loop control of the flow rate of each valve is inserted in the loop of closed-loop control of the injection speed V, due to differences in the specific positions of the two valves and the like, the two valves can perform different operations. As a result, for example, by performing control corresponding to the flow rate of each valve, the accuracy of control of the injection speed V can be improved.

[0243] The specific structure of the second control unit 5b in the first structural example ( Figure 12 ) may be any one of the various specific examples of the second control unit 5b described regarding the second structural example ( Figure 13 ). That is, the second control unit 5b may perform any one of PID control, PI control, PD control, ID control, P control, I control, and D control.

[0244] In the first configuration example ( Figure 12) In the description of [], regarding the control of each valve, the case of using a target speed lower than the original target speed (from a higher-level concept, the target speed after processing the original target speed) is described (from another perspective, using the processed deviation, or the case where the target value of the deviation is set to 0 and disappears). The same idea can also be applied to the various forms of closed-loop control described so far.

[0245] (6. Summary of the Embodiment)

[0246] As described above, the injection device 9 of the embodiment includes an injection cylinder 27, a first flow control valve and a second flow control valve (first valve 39A and second valve 39B), and a controller 5. The injection cylinder 27 is connected to a plunger 23 that injects a molding material (melt) into a mold (mold 101). The first valve 39A and the second valve 39B are connected in parallel with each other and together form an outlet throttle circuit 37A or an inlet throttle circuit 37B of the injection cylinder 27. The controller 5 sets the first valve 39A to the open state and the second valve 39B to the open state within one molding cycle.

[0247] In addition, the controller 5 outputs different control signals (SG1 and SG2) to the first valve 39A and the second valve 39B during at least a part of the above-mentioned one molding cycle. From another perspective, the controller 5 controls the first valve 39A and the second valve 39B according to different algorithms during at least a part of the above-mentioned one molding cycle. From yet another perspective, the controller 5 causes the first valve 39A and the second valve 39B to perform different actions during at least a part of the above-mentioned one molding cycle.

[0248] Therefore, through this specific method, it is possible to improve the control accuracy of the injection speed V, simplify the control, and / or make it easier to adjust the gain. The injection speed affects the quality of the molded part. Therefore, by improving the accuracy of the injection speed, for example, it is possible to finely adjust the quality of the molded part. Furthermore, the quality of the molded part can be improved. In addition, by making it easier to finely adjust the gain, it becomes easier to achieve the desired injection speed V, and furthermore, it becomes easier to obtain the desired quality. In addition, as Figure 11 illustrated in the flowchart of [], the step of causing only one of the valves to perform a specified action when specified conditions are met is an example of a method of controlling two valves according to different algorithms. And open-loop control and closed-loop control ( Figure 12 ), two closed-loop controls with different presences or absences of PID ( Figure 14 and Figure 15 ), and PID control with different gains ( Figure 16 ) are all examples of controls with different algorithms.

[0249] During the above-mentioned one-shot molding cycle, after starting injection by switching the first flow control valve (first valve 39A) from the closed state to the open state, the controller 5 can switch the second flow control valve (second valve 39B) from the closed state to the open state to set the cooperative state in which both the first valve 39A and the second valve 39B are in the open state, and continue injection in this cooperative state.

[0250] In this case, for example, as described in the explanations of the first and second operation examples ( Figure 5 ), and the fifth operation example ( Figure 9 ), the accuracy of the injection speed in the relatively initial stage of injection can be improved. As a result, for example, the flow of the molten liquid in the sleeve 21 and / or in the mold 101 can be controlled with high precision to improve the quality of the molded article. On the other hand, when the first valve 39A and the second valve 39B are brought into the cooperative state later, the working liquid can be supplied to the head side chamber 29h at a large flow rate to increase the injection speed. Furthermore, injection can be completed before the solidification of the molten liquid, improving the quality of the molded article.

[0251] The controller 5 can change the first flow control valve and the second flow control valve (first valve 39A and second valve 39B) to the above-mentioned cooperative state in the middle of the initial injection speed just after the start of injection.

[0252] In this case, for example, as described in the explanation of the middle part of the first operation example ( Figure 5 ), it is easy to make the change in the injection speed smooth when the injection speed transfers from the acceleration state to a constant speed. As a result, for example, the probability of a decrease in the quality of the molded article due to overshoot and / or undershoot of the injection speed can be reduced.

[0253] After the rise of the initial injection speed just after the start of injection ends, the controller 5 can change the first flow control valve and the second flow control valve (first valve 39A and second valve 39B) to the above-mentioned cooperative state, and control the injection speed at a constant speed in the cooperative state.

[0254] In this case, for example, as described in the explanation of the middle part of the second operation example ( Figure 5 ), the stability of the control in the acceleration section just after the start of injection can be improved. As a result, for example, the probability of generating specific waves in the molten liquid in the sleeve 21 is reduced, and the possibility of deviation in the amount of air entrained by the molten liquid is reduced. That is, the quality of the molded article is stable.

[0255] During at least a part of the above, the controller 5 can control the opening degree of the first flow control valve (first valve 39A) according to the change in the target value of the injection speed, and make the change in the opening degree of the second flow control valve (second valve 39B) corresponding to the change in the target value smaller than the change in the opening degree of the first valve 39A corresponding to the change in the target value, and control the opening degree of the second flow control valve according to the variation of the detected value of the injection speed with respect to the target value.

[0256] In this case, for example, as described in the explanation of the third operation example ( Figure 7 ), and the fourth operation example ( Figure 8 ), effects such as simplification of control, facilitation of gain adjustment, and improvement of resolution ability can be obtained. As a result, for example, the followability of the injection speed to the target value is improved, and the influence of external disturbance on the injection speed is reduced, and it is easy to make the actual injection speed close to the target value. Furthermore, the quality of the molded part is improved. In addition, as can be understood from the description so far, the control corresponding to the change in the target value of the injection speed and the control corresponding to the variation of the detected value of the injection speed with respect to the target value of the injection speed in the above paragraph can be either indirect speed control based on position control or direct speed control.

[0257] The controller 5 can perform open-loop control of the first flow control valve (first valve 39A) during at least a part of the above, and perform closed-loop control of the second flow control valve (second valve 39B) based on the detected value of the injection speed.

[0258] In this case, for example, as described above, a part or all of the third to sixth operation examples ( Figures 7 to 10 ) are realized. As described above, through these operations, effects such as improvement of the accuracy of the injection speed and facilitation of gain adjustment can be obtained, and furthermore, it is easy to improve the quality of the molded part. In addition, as can be understood from the description so far, the closed-loop control based on the detected value of the injection speed V in the above paragraph can be either indirect speed control based on position control or direct speed control.

[0259] During at least a part of the above, the controller 5 controls the first flow control valve (first valve 39A) through closed-loop control including at least proportional control (P control) based on the detected value of the injection speed V or the detected value of the position D of the plunger 23, and controls the second flow control valve (second valve 39B) through closed-loop control including at least derivative control (D control). At this time, for the proportional gains (Kp1, KP2), the first valve 39A is larger than the second valve 39B, and for the derivative gains (Kd1, Kd2), the second valve 39B is larger than the first valve 39A.

[0260] In this case, for example, as described above, the third operation example ( Figure 7 ) and the fourth operation example ( Figure 8 ) are implemented, and low-speed injection of the sixth operation example ( Figure 10 ) is implemented. As described above, by these operations, for example, effects such as an improvement in the accuracy of the injection speed and an easier adjustment of the gain can be obtained, and furthermore, it is easy to improve the quality of the molded part. In addition, as in the previous paragraph, for the proportional gain, when the first valve 39A is larger than the second valve 39B, the proportional gain Kp2 of the second valve 39B can also be 0. In other words, for the second valve 39B, P control may not be performed. The same applies when describing the magnitude relationship for the integral gain and the derivative gain.

[0261] The controller 5 can gradually increase the opening degree of the first flow control valve (the first valve 39A) during a specified period in the above-mentioned one-shot molding cycle, and temporarily increase the opening degree of the second flow control valve (the second valve 39B) at the beginning of the above-mentioned specified period.

[0262] The above-mentioned specified period is, for example, from time t0 to time t1 of the third operation example ( Figure 7 ), or from time t2 to time t2' of the fourth operation example ( Figure 8 ). In this case, for example, the deviation at the initial stage of acceleration can be reduced. This is effective in itself, and in the case of performing closed-loop control of the first valve 39A, the proportional gain of the first valve 39A can be reduced, so a reduction in overshoot is also expected. By reducing the deviation and the overshoot, the actual injection speed approaches the target value, so it is easy to improve the quality of the molded part. In addition, as can be understood from the description so far, the operations of the above-mentioned first valve 39A and second valve 39B can also be implemented by either open-loop control or closed-loop control.

[0263] The controller 5 can maintain the opened first flow control valve (the first valve 39A) at a constant opening degree during a specified period in which the target value of the injection speed V is constant in the above-mentioned one-shot molding cycle, and gradually increase the opening degree of the second flow control valve (the second valve 39B) during the above-mentioned specified period.

[0264] The above-mentioned specified period is, for example, after time t1 of the third operation example ( Figure 7 ), or the sixth operation example ( Figure 10from time t0 to time t2. In this case, for example, the pressure drop of the accumulator 41 can be compensated by the second valve 39B. On the other hand, the control of the first valve 39A can be set to a simple control that ignores the pressure drop of the accumulator 41, and it is also beneficial for gain adjustment. That is, the accuracy of the injection speed can be improved by simple control, and thus the quality of the molded part can be improved. In addition, as can be understood from the foregoing description, the operations of the first valve 39A and the second valve 39B can be implemented by either open-loop control or closed-loop control. For example, the maintenance of a constant opening of the first valve 39A can be performed by open-loop control or by closed-loop control including proportional control.

[0265] The controller 5 can set only one of the first flow control valve and the second flow control valve (the first valve 39A and the second valve 39B) to the open state during low-speed injection, and set both the first valve 39A and the second valve 39B to the open state during high-speed injection. For the effects in this case, refer to the description of the fifth operation example ( Figure 9 ).

[0266] The controller 5 can open the first flow control valve (the first valve 39A) with an opening degree below the first opening degree during low-speed injection, and open the second flow control valve (the second valve 39B) with a second opening degree that realizes a flow rate larger than the flow rate realized by the first valve 39A with the first opening degree. In addition, the controller 5 can, during high-speed injection, open one of the first valve 39A and the second valve 39B with an opening degree that realizes a flow rate larger than the flow rate realized by the second valve 39B with the second opening degree, and control the opening degree of the other of the first valve 39A and the second valve 39B through closed-loop control based on the detected value of the injection speed V.

[0267] In this case, for example, as described in the description of the fifth operation example ( Figure 9 ) and the sixth operation example ( Figure 10 ), the accuracy of the injection speed during low-speed injection can be improved, and a higher injection speed can be achieved during high-speed injection. As a result, for example, the entrainment of air caused by the melt during low-speed injection can be reduced with high precision, and high-speed injection can be completed in advance before the melt solidifies, improving the quality of the molded part. In addition, the operations of the first valve 39A and the second valve 39B during the above-mentioned low-speed injection and the operations of the "one side" of the first valve 39A and the second valve 39B during high-speed injection can be implemented by either open-loop control or closed-loop control. In addition, the closed-loop control based on the detected value of the injection speed V described in this paragraph, as can be understood from the foregoing description, can be either indirect speed control based on position control or direct speed control.

[0268] In the above-described embodiment, the die-casting machine 1 is an example of a molding machine. The mold 101 is an example of a mold. The molten metal is an example of a molding material. The first valve 39A is an example of a first flow control valve. The second valve 39B is an example of a second flow control valve.

[0269] The present invention is not limited to the above-exemplified embodiments and can be implemented in various ways.

[0270] The molding machine is not limited to a die-casting machine. For example, the molding machine can be another metal molding machine, an injection molding machine for molding resin, or a molding machine for molding a material obtained by mixing a thermoplastic resin or the like in wood powder. In addition, the molding machine is not limited to horizontal mold clamping and horizontal injection. For example, it can also be vertical mold clamping and vertical injection, vertical mold clamping and horizontal injection, or horizontal mold clamping and vertical injection. The die-casting machine is not limited to a cold chamber machine and can also be a hot chamber machine, for example.

[0271] Description of Reference Numerals

[0272] 1... Die-casting machine (molding machine), 5... Controller, 7... Mold clamping device, 9 (9A and 9B)... Injection device, 11... Extrusion device, 21... Plunger, 27... Injection cylinder, 37A... Outlet throttle circuit, 37B... Inlet throttle circuit, 39A... First valve (first flow control valve), 39B... Second valve (second flow control valve), 101... Mold (die), 107... Space (inside of the mold).

Claims

1. An injection device, characterized in that, it has: an injection cylinder connected to a plunger for injecting molding material into a mold; a first flow control valve and a second flow control valve, which are connected in parallel with each other and together form an outlet throttling circuit or an inlet throttling circuit of the injection cylinder; a controller that, within one molding cycle, sets the first flow control valve to an open state, sets the second flow control valve to an open state, and outputs different control signals to the first flow control valve and the second flow control valve during at least a part of the period.

2. An injection device, characterized in that, it has: an injection cylinder connected to a plunger for injecting molding material into a mold; a first flow control valve and a second flow control valve, which are connected in parallel with each other and together form an outlet throttling circuit or an inlet throttling circuit of the injection cylinder; a controller that, within one molding cycle, sets the first flow control valve to an open state, sets the second flow control valve to an open state, and controls the first flow control valve and the second flow control valve according to different algorithms during at least a part of the period.

3. An injection device, characterized in that, it has: an injection cylinder connected to a plunger for injecting molding material into a mold; a first flow control valve and a second flow control valve, which are connected in parallel with each other and together form an outlet throttling circuit or an inlet throttling circuit of the injection cylinder; a controller that, within one molding cycle, sets the first flow control valve to an open state, sets the second flow control valve to an open state, and makes the first flow control valve and the second flow control valve perform different actions during at least a part of the period.

4. The injection device according to any one of claims 1 to 3, characterized in that, within the one molding cycle, after the controller switches the first flow control valve from a closed state to an open state and starts injection, it switches the second flow control valve from a closed state to an open state, thereby setting it to a cooperative state in which both the first flow control valve and the second flow control valve are open, and continues injection in this cooperative state.

5. The injection device according to claim 4, characterized in that, the controller makes the first flow control valve and the second flow control valve transition to the cooperative state during the rise of the initial injection speed just after the start of injection.

6. The injection device according to claim 4, characterized in that, the controller makes the first flow control valve and the second flow control valve transition to the cooperative state after the rise of the initial injection speed just after the start of injection is completed.

7. The injection device according to any one of claims 1 to 3, characterized in that, The controller controls the opening degree of the first flow control valve according to the change of the target value of the injection speed during at least a part of the period, and makes the change of the opening degree of the second flow control valve corresponding to the change of the target value smaller than the change of the opening degree of the first flow control valve corresponding to the change of the target value, and controls the opening degree of the second flow control valve according to the variation of the detected value of the injection speed with respect to the target value.

8. The injection device according to any one of claims 1 to 3, wherein, the controller performs open-loop control of the first flow control valve during at least a part of the period, and performs closed-loop control of the second flow control valve based on the detected value of the injection speed.

9. The injection device according to any one of claims 1 to 3, wherein, the controller controls the first flow control valve by closed-loop control including at least proportional control based on the detected value of the injection speed or the detected value of the position of the plunger during at least a part of the period, and controls the second flow control valve by closed-loop control including at least derivative control. At this time, for the proportional gain, the first flow control valve is larger than the second flow control valve, and for the derivative gain, the second flow control valve is larger than the first flow control valve.

10. The injection device according to any one of claims 1 to 3, wherein, the controller gradually increases the opening degree of the first flow control valve during a specified period in the primary molding cycle, and temporarily increases the opening degree of the second flow control valve at the beginning of the specified period.

11. The injection device according to any one of claims 1 to 3, wherein, the controller maintains the opening degree of the opened first flow control valve at a constant opening degree during a specified period in the primary molding cycle when the target value of the injection speed is constant, and gradually increases the opening degree of the second flow control valve within the specified period.

12. The injection device according to any one of claims 1 to 3, wherein, the controller sets only one of the first flow control valve and the second flow control valve to the open state during low-speed injection, and sets both the first flow control valve and the second flow control valve to the open state during high-speed injection.

13. The injection device according to any one of claims 1 to 3, wherein, the controller opens the first flow control valve at an opening degree not exceeding a first opening degree during low-speed injection, and opens the second flow control valve at a second opening degree, and the second opening degree realizes a flow rate larger than the flow rate realized by the first flow control valve with the first opening degree; during high-speed injection, one of the first flow control valve and the second flow control valve is opened at an opening degree that realizes a flow rate larger than the flow rate realized by the second flow control valve with the second opening degree, and the opening degree of the other of the first flow control valve and the second flow control valve is controlled by closed-loop control based on the detected value of the injection speed.

14. A molding machine, wherein, comprising: an injection device according to any one of claims 1 to 3; a mold clamping device for holding the mold.

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