Injection device, molding machine, and method for manufacturing molded article

Abstract

The injection device (9) performs injection and pressure maintaining. The injection is an operation in which the molding material (molten liquid) in the sleeve (21) is pushed into the mold (space 107 of the mold 101) by the plunger (23). The pressure maintaining is an operation in which a predetermined set pressure (Pc1 or Pc2) is applied to the melt filled in the mold (101) by the plunger (23) for a certain period of time. The injection device (9) has a drive unit (25) connected to the plunger (23). The drive unit (25) applies, to the plunger (23), a drive force for reducing the pressure applied by the plunger (23) to a set pressure (Pc1) while reducing the pressure applied by the plunger (23) to the melt filled in the mold (101).

Description

Technical Field

[0001] The present invention relates to an injection device for injecting a molding material into a mold, a molding machine including the injection device, and a manufacturing method for manufacturing a molded product by injecting a molding material into a mold. The molding machine is, for example, a die casting machine for molding metal or an injection molding machine for molding resin. Background Art

[0002] In the die casting method, injection, pressurization and pressure holding are usually performed in sequence. In injection, the molding material in the sleeve is pushed out by the plunger and filled into the mold. In pressurization, the pressure applied by the plunger to the molding material filled into the mold is increased. In pressure holding, the pressure of the molding material is maintained at a predetermined set pressure (in other words, casting pressure or final pressure) by pressurization. Various structures for realizing such actions have also been proposed (for example, Patent Documents 1 to 6).

[0003] Patent Document 1 discloses a die casting machine in which a plunger is driven by an electric drive unit.

[0004] Patent Document 2 discloses a die casting machine in which a plunger is driven by a pressure-boosting injection cylinder. The die casting machine has an injection accumulator and a pressure-boosting accumulator, respectively.

[0005] Patent Document 3 discloses a die casting machine in which a plunger is driven by a single-tube injection cylinder. This die casting machine also has an injection accumulator and a pressure-increasing accumulator separately.

[0006] Patent Document 4 discloses a die casting machine in which a plunger is driven by an injection cylinder. This die casting machine can introduce the pressure of an accumulator to the rod side of the injection cylinder, thereby controlling the pressure acting on the molding material in a wide range.

[0007] Patent Document 5 discloses a die casting machine having the same structure as that of Patent Document 2. This die casting machine appropriately adjusts the pressure of a pressure boosting accumulator.

[0008] Patent Document 6 discloses a die casting machine having the same structure as that of Patent Document 2. This die casting machine appropriately adjusts the flow rate of the working fluid discharged from the cylinder for pressurization.

[0009] Prior art literature

[0010] Patent Literature

[0011] Patent Document 1: Japanese Patent Application Publication No. 2018-176192

[0012] Patent Document 2: Japanese Patent Application Publication No. 2005-21976

[0013] Patent Document 3: Japanese Patent Application Publication No. 2009-61458

[0014] Patent Document 4: Japanese Patent Application Publication No. 2004-276071

[0015] Patent Document 5: Japanese Patent Application Publication No. 2017-136618

[0016] Patent Document 6: Japanese Patent Application Laid-Open No. 11-156524

[0017] Problems to be solved by the invention

[0018] As a defect of molded products, burrs are known, which are caused by the molding material filled in the cavity between the fixed mold and the movable mold overflowing between the surfaces of the fixed mold and the movable mold that should contact each other. An injection device, a molding machine, and a method for manufacturing molded products that can reduce burrs are desired. Summary of the invention

[0019] An injection device according to one embodiment of the present invention performs injection and pressure holding. During the injection, the injection device pushes the molding material in the sleeve into the mold through the plunger. During the pressure holding, the injection device applies a predetermined set pressure to the molding material filled in the mold through the plunger for a certain period of time. The injection device has a driving unit connected to the plunger. The driving unit applies a driving force to the plunger to reduce the pressure applied by the plunger to the molding material filled in the mold to the set pressure.

[0020] A molding machine according to one aspect of the present invention includes the above-mentioned injection device and a mold clamping device that holds the mold.

[0021] A method for manufacturing a molded product according to one embodiment of the present invention comprises an injection step, a pressure holding step, and a decompression step. In the injection step, the molding material in the sleeve is pushed into the mold by the plunger. In the pressure holding step, a predetermined set pressure is applied to the molding material filled in the mold by the plunger for a certain period of time. In the decompression step, the pressure applied by the plunger to the molding material filled in the mold by the injection step is reduced while reaching the set pressure.

[0022] Effects of the Invention

[0023] According to the above-mentioned structure or step, burrs can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a side view partially including a cross-sectional view, showing the structure of a main part of the die casting machine according to the embodiment.

[0025] Figure 2 Yes means Figure 1 Schematic diagram of the structure of the injection device and local pressurizing device of the die-casting machine.

[0026] Figure 3 Yes means Figure 2 Schematic diagram of an example of the structure of the ACC pressure adjustment unit of the injection device.

[0027] Figure 4 (a) and Figure 4 (b) is used to illustrate Figure 2 Schematic diagram of the action of the injection device.

[0028] Figure 5 (a) and Figure 5 (b) means Figure 4 (b) Schematic diagram of the follow-up.

[0029] Figure 6 Yes means Figure 2 A graph showing the time-dependent changes in the injection speed and injection pressure of the injection device.

[0030] Figure 7 Yes means Figure 2 A flowchart of an example of steps of a process executed by a control device of an injection device.

[0031] Figure 8 (a) and Figure 8 (b) is a schematic diagram for explaining the operation of the injection device according to the second embodiment.

[0032] Fig. 9 (a) and Fig. 9 (b) means Figure 8 (b) Schematic diagram of the follow-up.

[0033] Fig.10 (a) and Fig.10 (b) is a schematic diagram for explaining the operation of the injection device according to the second embodiment.

[0034] Fig.11 (a) and Fig.11 (b) means Fig.10 (b) Schematic diagram of the follow-up.

[0035] Fig.12 This is a circuit diagram showing a part of a hydraulic system according to a modified example.

[0036] Fig.13 It is a schematic diagram for explaining the operation of the injection device according to the modified example. DETAILED DESCRIPTION

[0037] Hereinafter, multiple modes (implementations and variations) of the present invention will be described with reference to the accompanying drawings. In addition, for the modes described later in the multiple modes, basically only the differences from the modes described previously are described. For matters not specifically mentioned, they may be the same as the modes described previously, or they may be inferred from the modes described previously. In addition, for structures corresponding to each other in multiple modes, even if there are differences, for convenience, the same symbols are sometimes marked on each other.

[0038] Hereinafter, the gist of the embodiment of the present invention will be described first, and then more specific first to third embodiments and their modified examples will be described.

[0039] (Key points of injection device according to embodiment)

[0040] Figure 1 The figure is a side view partially including a cross-sectional view showing the structure of the main part of the die casting machine 1 of the present embodiment. The vertical direction on the paper is the vertical direction, and the horizontal direction on the paper and the direction through the paper are the horizontal directions.

[0041] The die casting machine 1 manufactures a die casting product (molded product) by, for example, injecting a liquid metal material (molten liquid) into a mold 101 (space 107 ) and solidifying the molten liquid in the mold 101 .

[0042] In general, in such a die casting machine 1, injection, pressurization and pressure holding are performed in sequence. In injection, the molten liquid in the sleeve 21 is pushed out by the plunger 23 and filled into the metal mold 101. In pressurization, the pressure applied by the plunger 23 to the molten liquid filled into the metal mold 101 is increased. In pressure holding, the pressure of the molten liquid is maintained at a predetermined set pressure (in other words, casting pressure or final pressure) by pressurization.

[0043] On the other hand, in the die casting machine 1 of the embodiment, decompression may be performed after injection and before pressure maintenance instead of pressurization. During decompression, for example, the pressure applied by the plunger 23 to the molding material filled in the metal mold 101 decreases and reaches the above-mentioned set pressure.

[0044] By such an action, for example, the possibility of burrs due to high pressure caused by pressurization can be reduced. In addition, decompression after injection means that the pressure at the time of injection completion is relatively high. Therefore, for example, during injection, the plunger 23 can be moved at high speed to fill the metal mold 101 with molten liquid without delaying the solidification of the molten liquid. In addition, since decompression is performed, for example, the clamping force can be reduced. As a result, for example, a large molded product can be manufactured using a die-casting machine with a relatively small clamping force.

[0045] The above is the main point of the die casting machine 1 of the embodiment. In the first to third embodiments described below, the specific structure for reducing pressure is different from each other. Hereinafter, the description will be roughly made in the following order.

[0046] 1. First Implementation Method ( Figures 1 to 7 )

[0047] 1.1. Overall structure of die casting machine 1 ( Figure 1 and Figure 2 )

[0048] 1.2. Structure of injection device ( Figure 2 )

[0049] 1.2.1. Injection cylinder

[0050] 1.2.2. Hydraulic device

[0051] 1.2.2.1. Overall structure of hydraulic device

[0052] 1.2.2.2. Pressure accumulator (liquid reservoir)

[0053] 1.2.2.3. Tanks and valves

[0054] 1.2.2.4. Pressure adjustment for each forming cycle

[0055] 1.2.3. Sensors

[0056] 1.3. Local compression device ( Figure 2 )

[0057] 1.4.ACC pressure adjustment unit ( Figure 3 )

[0058] 1.5. Operation of the injection device

[0059] 1.5.1. Overview of the operation of the injection device ( Figure 4 (a)~ Figure 5 (b))

[0060] 1.5.2. Examples of velocity and pressure changes ( Figure 6 )

[0061] 1.5.3. Example of control flow chart ( Figure 7 )

[0062] 1.6. Summary of the First Implementation

[0063] 2. Second Implementation Method ( Figure 8 and Fig. 9 )

[0064] 3. Third Implementation Method ( Fig.10 and Fig.11)

[0065] 4. Modifications

[0066] 4.1. Modification of the hydraulic device of the injection device ( Fig.12 )

[0067] 4.2. Modification of the operation of the injection device ( Fig.13 )

[0068] (1. First Embodiment)

[0069] (1.1. Overall structure of die casting machine)

[0070] Figure 1 It is a side view partially including a cross-sectional view, showing the structure of a main part of the die casting machine 1 according to the embodiment of the present invention.

[0071] As described above, the die-casting machine 1 injects liquid metal material (molten liquid) into the metal mold 101. From a high-level concept, the molten liquid is a metal material (forming material) in an unsolidified state. The unsolidified state includes a solid-liquid coexistence state in addition to the liquid state. The solid-liquid coexistence state is a semi-solidified state that solidifies from a liquid state, or a semi-molten state that melts from a solid state. The metal is, for example, aluminum or an aluminum alloy. In addition, in the description of the embodiment, the molten liquid is basically taken as an example of a metal material in an unsolidified state.

[0072] The metal mold 101 includes, for example, a fixed mold 103 and a movable mold 105. In the description of this embodiment, for convenience, a cross section of the fixed mold 103 or the movable mold 105 is represented by a shadow, but these molds can be straight-carved or nested. In addition, a core or the like can be combined on the fixed mold 103 and the movable mold 105.

[0073] The die casting machine 1 includes, for example, a machine body 3 that performs mechanical operations for molding, and a control unit 5 that controls the operations of the machine body 3 .

[0074] The machine body 3 includes, for example, a mold clamping device 7 for opening, closing and clamping the metal mold 101, an injection device 9 for injecting molten liquid into the metal mold 101, and a die casting product from a fixed mold 103 or a movable mold 105 ( Figure 1 The ejection device 11 is a movable mold 105. Figure 2 As shown, the machine body 3 may have a local pressurizing device 13 (hereinafter sometimes referred to as "pressurizing device 13") for locally pressurizing the molten liquid in the metal mold 101. In the machine body 3, the structure other than the injection device 9 (for example, the structure of the mold clamping device 7 and the ejection device 11) may be the same as various known structures.

[0075] During the molding cycle, the mold clamping device 7 moves the movable mold 105 toward the fixed mold 103 to close the mold. Furthermore, the mold clamping device 7 applies a mold clamping force corresponding to the extension amount of the connecting rod (symbol omitted) to the metal mold 101 to close the mold. A product portion 107a having the same shape as the molded product is formed in the metal mold 101 after mold closing (see Figure 2 ) space 107. The injection device 9 injects / fills the molten liquid into the space 107. The pressurizing device 13 applies pressure to the molten liquid at one or more appropriate positions in the space 107. The molten liquid in the space 107 is cooled and solidified by the heat taken away by the metal mold 101. That is, the molten liquid becomes a molded product. Afterwards, the mold clamping device 7 moves the movable mold 105 away from the fixed mold 103 to open the mold. At this time or afterwards, the ejection device 11 ejects the molded product from the movable mold 105.

[0076] The control unit 5 includes, for example, a control device 15 that performs various calculations and outputs control commands, an input device 17 that receives input operations from an operator, and a display device 19 that displays images. In another viewpoint, the control unit 5 also includes, for example, a control panel (not shown) having a power supply circuit and a control circuit, Figure 1 The operating units shown (symbols omitted).

[0077] The control device 15 is provided on, for example, a control panel (not shown) and Figure 1 The control device 15 can be appropriately divided or dispersed. For example, the control device 15 can be configured to include: a lower-level control device for each mold clamping device 7, injection device 9 and ejection device 11, and an upper-level control device that performs synchronization and other controls between the lower-level control devices.

[0078] The display device 19 and the input device 17 are included in, for example, an operating unit (symbol omitted). The operating unit can be set at an appropriate position, and in the illustrated example, it is set on a fixed die plate (symbol omitted) of the mold clamping device 7. The display device 19 is composed of, for example, a touch panel including a liquid crystal display or an organic EL display. The input device 17 is composed of, for example, a mechanical switch and the above-mentioned touch panel.

[0079] In addition, when the control unit 5, the control device 15, the input device 17 and / or the display device 19 are considered as components of the device included in the die casting machine 1, they can be considered as components of the device. For example, the control device 15 can be considered as a control device of the injection device 9.

[0080] (1.2. Overall structure of the injection device)

[0081] The injection device 9 includes, for example, a sleeve 21 communicating with the inside of the metal mold 101, a plunger 23 slidable in the sleeve 21, and a driving unit 25 driving the plunger 23. In the description of the injection device 9, the metal mold 101 side is sometimes referred to as the front side, and the opposite side is sometimes referred to as the rear side. In addition, the sleeve 21 and the plunger 23 can be regarded as consumables, so only the driving unit 25 can also be regarded as the injection device.

[0082] The sleeve 21 is, for example, a cylindrical member, and has a supply port 21a formed on its upper surface for receiving the melt into the sleeve 21. The plunger 23 has, for example, a plunger piece 23a slidable in the sleeve 21 in the front-rear direction, and a plunger rod 23b having a front end fixed to the plunger piece 23a.

[0083] After the mold 101 is closed by the mold closing device 7, a single shot of molten liquid is injected from the supply port 21a into the sleeve 21 by a liquid supply device (not shown). Then, the plunger 23 slides forward in the sleeve 21 from the position shown in the figure, so that the molten liquid in the sleeve 21 is pushed out (injected) into the metal mold 101.

[0084] Figure 2 It is a schematic diagram showing the structure of the driving unit 25 of the injection device 9.

[0085] The driving unit 25 is, for example, a hydraulically-type structure, and includes an injection cylinder 27 that drives the plunger 23 , and a hydraulic device 29 that supplies working fluid (for example, oil) to the injection cylinder 27 .

[0086] (1.2.1. Injection cylinder)

[0087] The injection cylinder 27 may adopt various structures, for example, a known structure may be adopted. In the present embodiment, the injection cylinder 27 is a so-called booster type.

[0088] The injection cylinder 27 is coaxially arranged behind the plunger 23. The injection cylinder 27 includes, for example, a cylinder member 31, an injection piston 33 and a booster piston 35 slidable inside the cylinder member 31, and a piston rod 37 extending forward (toward the plunger 23) from the injection piston 33.

[0089] The cylinder component 31 is, for example, a roughly cylindrical component. The shape of the internal cross section of the cylinder component 31 (the cross section perpendicular to the axial direction) is, for example, circular. In addition, for convenience, it is assumed that the internal cross section of the cylinder component 31 and the cross section of the piston are circular. Therefore, for example, the size relationship of the diameter is the same as the size relationship of the cross section. The outer shape (outer shape) of the cylinder component 31 can be a suitable shape such as a rectangular parallelepiped.

[0090] The cylinder member 31 is immovable relative to the fixed die plate of the mold clamping device 7. The cylinder member 31 includes an injection cylinder portion 31e and a booster cylinder portion 31f connected to the rear of the injection cylinder portion 31e. The injection cylinder portion 31e has a substantially constant inner diameter in the axial direction. The booster cylinder portion 31f includes a small-diameter cylinder portion 31x connected to the rear of the injection cylinder portion 31e, and a large-diameter cylinder portion 31y connected in series to the rear end of the small-diameter cylinder portion 31x. The inner diameter of the large-diameter cylinder portion 31y is larger than the inner diameter of the small-diameter cylinder portion 31x.

[0091] In addition, Figure 2 In the example, the small diameter cylinder portion 31x is connected in series with the rear end of the injection cylinder portion 31e, and the diameter of the small diameter cylinder portion 31x is the same as the diameter of the injection cylinder portion 31e. However, as described later Figure 4 As shown in (a), the diameter of the small-diameter cylinder portion 31x may be different from the diameter of the injection cylinder portion 31e. In addition, although not specifically shown, it is known that the small-diameter cylinder portion 31x may not be connected in series with the rear end of the injection cylinder portion 31e according to the known situation of the separate type booster cylinder.

[0092] The injection piston 33 is slidably disposed in the injection cylinder portion 31e. The shape of the injection piston 33 is, for example, roughly cylindrical. The diameter of the injection piston 33 is roughly the same as the inner diameter of the injection cylinder portion 31e. A gasket, not shown in the figure, may be sandwiched between the injection piston 33 and the injection cylinder portion 31e. In the case where a gasket is sandwiched, it also appears that the injection piston 33 slides in the injection cylinder portion 31e (cylinder component 31). The same is true for other components (such as the booster piston 35). The space inside the injection cylinder portion 31e is divided by the injection piston 33 into a rod side chamber 31r on the piston rod 37 side and a head side chamber 31h on the opposite side.

[0093] The booster piston 35 has a small-diameter piston 35x that slides in the small-diameter cylinder portion 31x and a large-diameter piston 35y that slides in the large-diameter cylinder portion 31y. The large-diameter piston 35y is connected to the rear end of the small-diameter piston 35x. The small-diameter piston 35x and the large-diameter piston 35y are respectively, for example, roughly cylindrical components. In addition, unlike the example shown in the figure, a connecting portion having a diameter smaller than the diameter of the small-diameter piston 35x can also be formed between the small-diameter piston 35x and the large-diameter piston 35y. The interior of the large-diameter cylinder portion 31y is divided into a front chamber 31a and a rear chamber 31b by the large-diameter piston 35y.

[0094] The piston rod 37 is, for example, a substantially cylindrical member. The diameter of the piston rod 37 is smaller than the diameter of the injection piston 33. The difference can be appropriately set. The piston rod 37 extends to the outside of the cylinder member 31, and its front end is connected to the rear end of the plunger 23 through the coupling 24.

[0095] The injection piston 33 is advanced by supplying the working fluid to the head side chamber 31h. As a result, the plunger 23 connected to the injection piston 33 is advanced via the piston rod 37 and the coupling 24. Furthermore, the molten liquid in the sleeve 21 is injected into the space 107. In other words, injection in a narrow sense (injection not including pressurization or decompression) is performed.

[0096] After that, in a conventional die-casting machine (die-casting machine that does not perform decompression), working fluid is supplied to the rear chamber 31b. Since the area (pressure-bearing area) of the pressure from the working fluid in the rear chamber 31b that the booster piston 35 receives in the forward direction is larger than the area (pressure-bearing area) of the pressure from the working fluid in the small-diameter cylinder 31x that the booster piston 35 receives in the rear direction, a pressure higher than the pressure in the rear chamber 31b can be applied to the small-diameter cylinder 31x (and the head chamber 31h). This pressure is transmitted to the molding material filled in the space 107 via the injection piston 33, the piston rod 37, and the plunger 23. Thus, a boost is performed to increase the pressure of the molding material. The action when decompression is performed will be described later.

[0097] In addition, the front chamber 31a may be filled with the working fluid or not. In the latter embodiment, for example, the front chamber 31a may be open to the atmosphere. In this case, a small amount of working fluid (oil) for lubrication may also be arranged in the front chamber 31a.

[0098] When the front chamber 31a is filled with working fluid, the working fluid may be used for a certain purpose or may not be used. As an example of the former, for example, a method of supplying working fluid to the front chamber 31a to apply a driving force to the booster piston 35 in the rear direction may be cited. In addition, for example, a method of prohibiting the discharge of working fluid from the front chamber 31a and prohibiting the booster piston 35 from moving forward unintentionally may be cited. In addition, as an example of not utilizing the working fluid that fills the front chamber 31a, a method of connecting only the front chamber 31a and the tank may be cited.

[0099] (1.2.2. Hydraulic device)

[0100] (1.2.2.1. Overall structure of hydraulic device)

[0101] The hydraulic device 29 is configured to be able to perform decompression after injection and before pressure maintenance as described above. More specifically, the hydraulic device 29 is configured to be able to reduce the pressure of the head side chamber 31h after the working fluid is supplied to the head side chamber 31h and the injection is performed. Furthermore, the hydraulic device 29 can also increase the pressure after injection and before pressure maintenance instead of reducing the pressure. The specific situation is as follows.

[0102] The hydraulic device 29 includes, for example, an injection accumulator (injection reservoir) 39 and an adjustment accumulator (adjustment reservoir) 41 capable of holding a working fluid under pressure. The injection accumulator 39 communicates with the head side chamber 31h, and the adjustment accumulator 41 communicates with the rear side chamber 31b.

[0103] When the injection start condition is satisfied, the injection accumulator 39 supplies the working fluid to the head side chamber 31h. As a result, the pressure of the head side chamber 31h increases, and the injection piston 33 moves forward, thereby performing the injection.

[0104] The pressure in the accumulator 41 is adjusted to be low, and the hydraulic pressure in the rear chamber 31b is absorbed after injection. This allows the booster piston 35 to retreat, and the pressure in the head chamber 31h is reduced. As a result, the pressure applied by the plunger 23 to the melt is also reduced. That is, the pressure is reduced.

[0105] In addition, for example, when the working fluid flows from the rear chamber 31b to the regulating accumulator 41, if the volume of the flow path therebetween is large and the amount of movement of the boosting piston 35 is small, the working fluid in the rear chamber 31b does not reach the regulating accumulator 41. Even in this case, for convenience, it is sometimes expressed that the regulating accumulator 41 absorbs the working fluid from the rear chamber 31b. The same is true for other components (such as the injection accumulator 39) and the supply of working fluid.

[0106] When the pressure is increased instead of reduced, the pressure in the regulating accumulator 41 is high. After the injection, the regulating accumulator 41 supplies the working fluid to the rear chamber 31b. As a result, the pressure applied to the melt by the plunger 23 increases.

[0107] The structure of the hydraulic circuit for realizing the above-mentioned operation can be various. In the example shown in the figure, it is as follows.

[0108] The hydraulic device 29 includes a flow path (symbol omitted) connecting the injection accumulator 39 and the head side chamber 31h, and an injection valve 43 located in the flow path. In addition, the hydraulic device 29 includes a flow path (symbol omitted) connecting the adjustment accumulator 41 and the rear side chamber 31b, and an adjustment valve 45 located in the flow path. Furthermore, the hydraulic device 29 includes a flow path (symbol omitted) connecting the rod side chamber 31r and the tank 47, and a rod side valve 49 located in the flow path. A back pressure elimination cylinder 51 for eliminating the back pressure of the injection cylinder 27 is connected between the rod side valve 49 and the tank 47. In addition, the combination of the adjustment accumulator 41 and the components for causing the hydraulic pressure of the adjustment accumulator 41 to act on the injection cylinder 27 (in the example shown in the figure, the flow path connecting the two and the adjustment valve 45) is sometimes referred to as a pressure adjustment unit 40.

[0109] exist Figure 2In the figure, the hydraulic device 29 only represents the main parts related to injection and decompression. That is, the hydraulic device 29 can have various components not shown in the figure. The various components can be the same as the known structure. For example, the hydraulic device 29 can have a pump. The pump, for example, helps to supply working fluid to the rod side chamber 31r to make the injection piston 33 retreat, or supply working fluid to the injection accumulator 39 and the adjustment accumulator 41 to accumulate pressure in these accumulators. Of course, flow paths and valves for such actions can also be provided. In addition, for example, the hydraulic device 29 can have flow paths and valves connecting these cylinder chambers and pumps and / or tanks 47 in order to supply and discharge working fluid to the head side chamber 31h, the front side chamber 31a and / or the rear side chamber 31b as needed. In addition, for example, the hydraulic device 29 can also have a circulation circuit connecting the head side chamber 31h and the rod side chamber 31r.

[0110] (1.2.2.2. Accumulator)

[0111] The injection accumulator 39 and the regulating accumulator 41 may be accumulators (liquid reservoirs) of various forms. In addition, in the following description, with regard to matters that can be common to the injection accumulator 39 and the regulating accumulator 41, sometimes only one of the accumulators is described, and the symbols related to the other accumulator are indicated in parentheses.

[0112] The injection accumulator 39 (41) may be in the form of, for example, a weight type, a spring type, a pneumatic type, a cylinder type, or an air bag type. In the weight type, pressure is applied to the working fluid by the weight of the weight. In the spring type, pressure is applied to the working fluid by the restoring force of the spring. In the pneumatic type, the compressed gas directly contacts the working fluid and applies pressure to the working fluid. In the cylinder type, the compressed gas applies pressure to the working fluid via a piston. In the air bag type, the compressed gas applies pressure to the working fluid via a flexible air bag (diaphragm). In the pneumatic type, the cylinder type, and the air bag type, the gas is, for example, air or nitrogen. The form of the injection accumulator 39 and the form of the adjustment accumulator 41 may be the same as each other (the example shown in the figure) or different from each other.

[0113] In the illustrated example, the injection accumulator 39 and the adjustment accumulator 41 are both of the cylinder type. That is, although no special symbols are marked, the injection accumulator 39 (41) has: a cylinder, and a piston that slides axially in the cylinder. The interior of the cylinder is divided by the piston into a liquid chamber (the cylinder chamber on the lower side in the figure) where the working fluid exists, and a gas chamber on the opposite side. The gas in the gas chamber is compressed, thereby applying pressure to the working fluid in the liquid chamber through the piston. The hydraulic device 29 may or may not have a tank not shown in the figure that is connected to the gas chamber of each accumulator. The tank can be, for example, a pneumatic accumulator, which helps to adjust the pressure of the injection accumulator 39 (41) by being supplied with working fluid.

[0114] Although it depends on the type of accumulator, the pressure of the injection accumulator 39 (41) varies during the molding cycle. For example, when the working fluid is supplied from the injection accumulator 39 to the head side chamber 31h for injection, the pressure of the injection accumulator 39 decreases. However, in the description of the embodiment, for convenience, such pressure changes are sometimes ignored. In the case where the pressure of the accumulator is described without mentioning a specific time in the molding cycle, it is hoped that it is reasonably determined at which time the pressure is.

[0115] The pressure of the injection accumulator 39 can be set in the same manner as in a normal die casting machine. The specific value thereof varies depending on the performance required of the die casting machine, and is set to be 13 MPa or more and 14 MPa or less, for example.

[0116] The pressure of the regulating accumulator 41 can be set relatively low to enable a decompression action. For example, consider a state where the pressure of the injection accumulator 39 is applied to the head side chamber 31h, and the pressure is applied to the rear side chamber 31b via the booster piston 35. The pressure of the rear side chamber 31b at this time is the size of the square of the ratio obtained by multiplying the pressure of the injection accumulator 39 by the diameter of the small diameter piston 35x divided by the diameter of the large diameter piston 35y (in other viewpoints, the ratio obtained by dividing the cross-sectional area of ​​the small diameter piston 35x by the cross-sectional area of ​​the large diameter piston 35y). The pressure of the rear side chamber 31b is referred to as the "first pressure". The pressure of the regulating accumulator 41 is, for example, lower than the first pressure. Thus, for example, even in a state where the injection accumulator 39 applies pressure to the head side chamber 31h and the regulating accumulator 41 applies pressure to the rear side chamber 31b, the booster piston 35 is allowed to retreat. Furthermore, decompression can be achieved. In addition, as will be described below, even if the pressure of the regulating accumulator 41 is not lower than the first pressure, a decompression action is possible.

[0117] As described above, when the pressure of the regulating accumulator 41 is lower than the first pressure, in more detail, the pressures of the injection accumulator 39 and the regulating accumulator 41 used for the comparison can be set to, for example, the pressure when the injection is completed (for example, when the injection valve 43 is closed as described below). This is because, according to the idea of ​​the previous paragraph, by making the pressure at the time of injection completion satisfy the above relationship, it is possible to reduce the pressure. In addition, the pressure of the regulating accumulator 41 can be used to compare, for example, the highest pressure in the molding cycle. That is, the condition that satisfies the requirement that the pressure of the regulating accumulator 41 is lower than the first pressure can be stricter.

[0118] In the case where the adjustment accumulator 41 is used for boosting, the pressure of the adjustment accumulator 41 can be set in the same manner as the pressure of the boosting accumulator of a conventional die-casting machine. For example, the pressure of the adjustment accumulator 41 is higher than the above-mentioned first pressure. Thus, boosting is possible. For example, the pressure of the adjustment accumulator 41 can be equal to or greater than the pressure of the injection accumulator. In addition, for example, as in the case of decompression, the pressure for comparison can be the pressure at the time when the injection is completed. However, the pressure of the injection accumulator 39 can also be the pressure before the injection is completed (in other words, before the pressure drops). That is, the condition that satisfies the requirement that the pressure of the adjustment accumulator 41 is higher than the first pressure can be stricter. In addition, with regard to the pressure of the adjustment accumulator 41, the pressure at the time of boosting (and then maintaining pressure) (the lowest pressure in the forming cycle) can also be used for comparison.

[0119] The die casting machine 1 (or the injection device 9 ) may include an ACC pressure regulating unit 53 for regulating the pressure of the accumulator 41 so as to selectively reduce or increase the pressure. The ACC pressure regulating unit 53 will be described later.

[0120] (1.2.2.3. Tanks and valves)

[0121] The tank 47 is, for example, an open tank, and holds the working fluid at atmospheric pressure. The pressure of the working fluid in the tank 47 is sometimes referred to as the tank pressure. In an open tank, the pressure of the working fluid is approximately equal to the atmospheric pressure (if the influence of the working fluid's own weight is ignored). When the cylinder chamber such as the rod side chamber 31r is connected to the tank 47, the pressure of the working fluid in the rod side chamber 31r or the head side chamber 31h basically becomes the tank pressure.

[0122] The structure of the injection valve 43 is arbitrary as long as it can open and close the flow path connecting the injection accumulator 39 and the head side chamber 31h. In the example shown in the figure, the injection valve 43 is composed of a servo valve (more specifically, a 2-port 2-position (2-way 2-position) switching valve with a servo valve function). The servo valve is used in a servo mechanism and can modulate the flow or pressure steplessly (continuously and at any value) according to an input signal. The servo valve can be, for example, a valve in which the valve core of the opening and closing port is directly driven by a solenoid, or a valve in which the valve core is indirectly driven by a solenoid via a pilot pressure. In addition, the servo valve as the injection valve 43 is configured to function as a flow control valve. In other words, the injection valve 43 constitutes a so-called inlet throttling circuit that controls the forward speed of the injection piston 33 by the flow of the working fluid supplied to the head side chamber 31h. The flow control valve can be, for example, a flow regulating valve with pressure compensation that can keep the flow constant even if there is a pressure change.

[0123] The structure of the regulating valve 45 is arbitrary as long as it can open and close the flow path connecting the regulating accumulator 41 and the rear chamber 31b. In the example shown in the figure, the regulating valve 45 is composed of a servo valve, a 2-port 2-position (2-way 2-position) switching valve, and a flow control valve, similarly to the injection valve 43. Therefore, the above description of the injection valve 43 can be applied to the regulating valve 45. The structure of the regulating valve 45 and the structure of the injection valve 43 can be the same or different.

[0124] The structure of the rod side valve 49 is arbitrary as long as it can open and close the flow path connecting the rod side chamber 31r and the tank 47. In the example shown in the figure, the rod side valve 49 is formed by a pilot check valve. The check valve allows flow from the rod side chamber 31r to the tank 47, but prohibits flow to the opposite side. In addition, the check valve prohibits flow on both sides when the pilot pressure is introduced. In addition, the rod side valve 49 can also be composed of a flow control valve (such as a servo valve and / or a flow regulating valve with pressure compensation) differently from the example shown in the figure. That is, the rod side valve 49 can also constitute a so-called outlet throttling circuit that controls the forward speed of the injection piston 33 by the flow rate of the working fluid discharged from the rod side chamber 31r. The outlet throttling circuit can replace the inlet throttling circuit or be provided on the basis of it.

[0125] (1.2.2.4. Pressure adjustment for each forming cycle)

[0126] As described above, the pressure of the injection accumulator 39 decreases during the molding cycle. For example, when the working fluid is supplied from the injection accumulator 39 to the head side chamber 31h for injection, the pressure of the injection accumulator 39 decreases. Therefore, for example, the injection accumulator 39 can be accumulated to a predetermined target pressure in each molding cycle. The structure and operation for this purpose may be various and may be the same as a known method.

[0127] For example, the injection device 9 supplies working fluid to the injection accumulator 39 from a pump (not shown) to accumulate pressure in the injection accumulator 39. The hydraulic circuit for this purpose can be appropriately configured. Pressure accumulation can be performed at an appropriate time in the molding cycle. For example, pressure accumulation can be performed at an appropriate time after the supply of working fluid from the injection accumulator 39 to the head side chamber 31h is completed (for example, after the injection is completed) and before the supply of working fluid from the injection accumulator 39 to the head side chamber 31h starts in the next molding cycle (for example, before the injection starts).

[0128] In addition, instead of using a pump, the piston rod 37 (and the injection piston 33) may be retracted by an electric motor to return the working fluid in the head side chamber 31h to the injection accumulator 39. Alternatively, another cylinder different from the injection cylinder 27 may be driven by an electric motor to supply working fluid to the rod side chamber 31r from the other cylinder to retract the injection piston 33 and return the working fluid in the head side chamber 31h to the injection accumulator 39. Alternatively, the working fluid may be supplied to the injection accumulator 39 directly from the other cylinder or via the head side chamber 31h.

[0129] Similarly, when the injection device 9 of the present embodiment performs pressure boosting, the pressure of the regulating accumulator 41 decreases during the molding cycle. For example, when the working fluid is supplied from the regulating accumulator 41 to the rear chamber 31b for pressure boosting, the pressure of the regulating accumulator 41 decreases. Therefore, for example, the regulating accumulator 41 can be pressurized to a predetermined target pressure in each molding cycle. The structure and operation for this purpose may be various and may be the same as a known method.

[0130] For example, the injection device 9 supplies working fluid to the regulating accumulator 41 from a pump not shown in the figure to accumulate pressure in the regulating accumulator 41. The hydraulic circuit used for this purpose can be appropriately constructed. Pressure accumulation can be performed at an appropriate time in the forming cycle. For example, pressure accumulation can be performed at an appropriate time after the supply of working fluid from the regulating accumulator 41 to the rear chamber 31b is completed (for example, after the pressurization is completed or after the pressure maintenance is completed) to before the supply of working fluid from the regulating accumulator 41 to the rear chamber 31b in the next forming cycle begins (for example, before the pressurization begins).

[0131] Alternatively, without using a pump, the piston rod 37 (and the injection piston 33) may be retracted by an electric motor in a state where the discharge of the working fluid from the head side chamber 31h is prohibited, and the booster piston 35 may be retracted, so that the working fluid in the rear side chamber 31b may be returned to the regulating accumulator 41. Alternatively, a cylinder other than the injection cylinder 27 may be driven by an electric motor, and the working fluid may be supplied from the cylinder to the rod side chamber 31r, so that the injection piston 33 may be retracted, the booster piston 35 may be retracted, and the working fluid in the rear side chamber 31b may be returned to the regulating accumulator 41. Furthermore, the working fluid may be supplied from the other cylinder to the head side chamber 31h and / or the front side chamber 31a, so that the booster piston 35 may be retracted, and the working fluid in the rear side chamber 31b may be returned to the regulating accumulator 41. Furthermore, the working fluid may be supplied from the other cylinder to the regulating accumulator 41 directly or via the rear side chamber 31b.

[0132] When the injection device 9 of the present embodiment performs decompression, the pressure of the adjustment accumulator 41 decreases or increases compared to before the start of decompression when the pressure maintenance is completed, depending on the specific method of decompression. Therefore, for example, the adjustment accumulator 41 can be adjusted to a predetermined target pressure in each molding cycle. The structure and operation for this purpose can be various.

[0133] For example, when the pressure of the adjustment accumulator 41 is reduced, the pressure of the adjustment accumulator 41 can be adjusted in the same manner as when the pressure is increased. In a conventional die casting machine that does not perform pressure reduction, the pressure of the pressure accumulator for pressure increase is sometimes reduced according to the forming conditions before the forming cycle, and the pressure of the pressure accumulator is adjusted to the target pressure. When the pressure of the adjustment accumulator 41 increases due to pressure reduction, this structure can be used to adjust the pressure of the accumulator 41 in each forming cycle. In addition, the timing of adjustment can be the same as in the case of pressure increase, for example.

[0134] In addition, for example, when the amount of the working fluid in the combination of the adjustment accumulator 41, the rear chamber 31b, and the flow path connecting the two is constant from the start of decompression to the completion of pressure maintenance, and the pressure of the adjustment accumulator 41 decreases or increases due to the movement of the booster piston 35 from the initial position at the start of decompression, the pressure can be adjusted by moving the booster piston 35 to the initial position. This movement can be achieved, for example, by supplying or discharging the working fluid to the front chamber 31a and / or the head chamber 31h. In addition, for example, when the pressure of the adjustment accumulator 41 increases, the working fluid of the adjustment accumulator 41 can be discharged to the tank 47 in an appropriate amount.

[0135] (1.2.3. Sensor)

[0136] The injection device 9 has various sensors not shown in the figure in order to grasp the operation of the drive unit 25 and the like. The control device 15 controls the drive unit 25 based on the detection values ​​of the various sensors. The various sensors can be provided in the same manner as known sensors. Although not particularly shown in the figure, for example, they are as follows.

[0137] The injection device 9 may include: a position sensor for detecting the position and speed of the plunger 23, and a pressure sensor for detecting the pressure applied by the plunger 23 to the molten liquid. The position sensor may be, for example, a magnetic or optical linear encoder, or a laser length measuring instrument. The pressure sensor may be, for example, a sensor for detecting the pressure of the head side chamber 31h. The pressure of the head side chamber 31h may be converted into the pressure applied by the plunger 23 to the molten liquid using the diameter of the injection piston 33 and the diameter of the plunger piece 23a. In addition to detecting the pressure of the head side chamber 31h, the pressure of the rod side chamber 31r may also be detected.

[0138] In addition, the injection device 9 may further include a pressure sensor for detecting the pressure of the injection accumulator 39 and a pressure sensor for detecting the pressure of the adjustment accumulator 41. These pressure sensors may detect the pressure of the liquid chamber or the pressure of the gas chamber. In addition, the pressure sensor may detect the pressure of the flow path close to the accumulator as long as it can substantially detect the pressure of the accumulator.

[0139] (1.3. Local pressurization device)

[0140] The pressurizing device 13 applies pressure to the molten liquid at one or more appropriate positions in the space 107. As a result, shrinkage cavities (cavities caused by the solidification and shrinkage of the molten material) can be reduced. As a result, for example, even if the pressure is reduced instead of pressurized after injection, and the pressure applied to the molten liquid by the plunger 23 is reduced, the quality from the perspective of shrinkage cavities can be maintained. In addition, unlike the description of this embodiment, the pressurizing device 13 can also be regarded as a component of the injection device 9.

[0141] The pressure applied to the melt by the pressurizing device 13 (more specifically, the pressurizing member 61) may be lower, equal, or higher than the pressure applied to the melt by the plunger 23 (more specifically, the set pressure during pressure maintenance). This applies not only to the case of decompression but also to the case of pressurization instead of decompression.

[0142] The structure of the pressurizing device 13 may be various, for example, it may be a known structure. The pressurizing device 13 includes: a pressurizing member 61 that directly pressurizes the melt by contacting the melt, and a driving unit (63 and 65) that drives the pressurizing member 61. The driving unit may be electric or hydraulic. Figure 2 In the figure, a hydraulic drive unit is exemplified, and the drive unit includes a pressurizing cylinder 63 and a hydraulic device 65 that supplies a working fluid to the pressurizing cylinder 63 .

[0143] In addition, the pressurizing device may be defined to include the pressurizing component 61 or not. This is because the pressurizing component 61 can be replaced by replacing the metal mold 101. The same is true for the pressurizing cylinder 63. That is, only the hydraulic device 65 may be regarded as the pressurizing device. In the description of the embodiment, for convenience, the pressurizing device 13 is sometimes expressed as including the pressurizing component 61 and the pressurizing cylinder 63.

[0144] The number, position and shape of the pressurizing component 61 are arbitrary. For example, the pressurizing component 61 may be a pin-shaped component. The pressurizing component 61 may be arranged on the fixed mold 103 (the example shown in the figure) or on the movable mold 105. The pressurizing component 61 may be located in the overflow portion 107b on the outside of the product portion 107a having the same shape as the die-cast product in the space 107. In addition, a plurality of pressurizing components 61 may be arranged at a plurality of positions. In addition, in the following description, for the sake of convenience, sometimes a specific description is not given but the description is focused on one pressurizing component 61.

[0145] Any number of pressurizing cylinders 63 may be provided. One pressurizing cylinder 63 may drive one pressurizing component 61 or more than two pressurizing components 61 so that the ejection device 11 drives more than two ejection pins. Although not specifically marked, the pressurizing cylinder 63 has, for example, a cylinder portion, a piston sliding in the cylinder portion, and a piston rod fixed to the piston and extending from the cylinder portion. The piston divides the cylinder portion into a rod side chamber on the side where the piston rod extends and a head side chamber on the opposite side. One of the cylinder portion and the piston rod (the latter in the illustrated example) is fixed to the pressurizing component 61, and the other is fixed to the fixed mold 103 or the movable mold 105 (the fixed mold 103 in the illustrated example). The pressurizing component 61 is moved toward the space 107 by supplying working fluid to one of the rod side chamber and the head side chamber (the head side chamber in the illustrated example).

[0146] The hydraulic device 65 is configured, for example, to supply working fluid to a cylinder chamber (in the illustrated example, the head side chamber) of the rod side chamber and the head side chamber of the pressurizing cylinder 63 to which the working fluid is supplied at least when the pressurizing member 61 moves toward the space 107. Although not particularly illustrated, the hydraulic device 65 includes, for example, a pump, a tank, an accumulator, various flow paths that interconnect these elements and the pressurizing cylinder 63, and various valves located in the flow paths. In addition, a part of the components of the hydraulic device 65 may be shared with the hydraulic device 29 of the injection device 9.

[0147] (1.4.ACC pressure adjustment unit)

[0148] As described in the description of the regulating accumulator 41 , the die casting machine 1 (or the injection device 9 ) may include the ACC pressure regulating unit 53 for regulating the pressure of the regulating accumulator 41 so as to selectively reduce or increase the pressure.

[0149] Here, in the description of the hydraulic device 29, it is described that the pressure of the adjustment accumulator 41 can be adjusted for each forming cycle. On the other hand, the ACC pressure adjustment unit 53 adjusts the pressure of the adjustment accumulator 41 so that it can selectively reduce and increase the pressure, and therefore, the range of this adjustment is generally larger than the adjustment range of each forming cycle as described above. The specific width of its adjustment range and the specific degree of difference from the adjustment range of each forming cycle can be appropriately set based on the performance required of the injection device 9, etc. For example, the width of the adjustment range of the pressure of the adjustment accumulator 41 by the ACC pressure adjustment unit 53 (the pressure difference from the lower limit to the upper limit) can be more than 2 times or more than 5 times the pressure at the center of its adjustment range, or it can be less than 8 times or less than 6 times.

[0150] In another viewpoint, in order to achieve supercharging, the pressure of the regulating accumulator 41 is made higher than the first pressure described above (the value of converting the pressure of the injection accumulator 39 into the pressure of the rear chamber 31b). In the case of supercharging, the adjustment range of the pressure of the regulating accumulator 41 for each molding cycle is higher than the first pressure. On the other hand, the adjustment range of the pressure of the regulating accumulator 41 by the ACC pressure regulating unit 53 covers from a pressure lower than the first pressure to a pressure higher than the first pressure. That is, the adjustment range of the pressure of the ACC pressure regulating unit 53 includes a range lower than the adjustment range of the pressure of each molding cycle of the existing supercharging accumulator.

[0151] Figure 3 It is a schematic diagram showing an example of the configuration of the ACC pressure regulating unit 53 .

[0152] The ACC pressure regulator 53 is configured to discharge gas from the gas chamber of the regulating accumulator 41 when reducing the pressure of the regulating accumulator 41 for decompression, and to supply gas to the gas chamber of the regulating accumulator 41 when increasing the pressure of the regulating accumulator 41 for pressure increase.

[0153] In addition, the pressure adjustment in each forming cycle in the conventional boosting accumulator is usually performed by supplying working fluid to the boosting accumulator, unlike the adjustment of the ACC pressure adjustment unit 53 in the illustrated example. Unlike the illustrated example, the ACC pressure adjustment unit 53 may be configured to adjust the pressure of the accumulator 41 to a pressure for decompression or a pressure for boosting by supplying working fluid. In this case, part or all of the ACC pressure adjustment unit 53 may be common to the structure for performing pressure adjustment in each forming cycle.

[0154] In the example shown in the figure, more specifically, when the ACC pressure regulating unit 53 discharges gas from the regulating accumulator 41, the discharged gas is stored in the tank 71. In addition, when the ACC pressure regulating unit 53 supplies gas to the regulating accumulator 41, the gas in the tank 71 is supplied to the regulating accumulator 41. Thus, for example, it is possible to switch between decompression and pressure increase without wasting a specific type of gas (for example, nitrogen).

[0155] The specific structure for realizing the above-mentioned action can be various structures. In the example shown in the figure, the ACC pressure adjustment unit 53 has: a cylinder 73, a motor 75 driving the cylinder 73, and pilot check valves 77A to 77D. The cylinder 73 sucks or sends out gas through the reciprocating motion of the piston 73b relative to the cylinder member 73a. The check valve 77A and the check valve 77D are connected in parallel with each other between the regulating accumulator 41 and the cylinder 73. The check valve 77B and the check valve 77C are connected in parallel with each other between the cylinder 73 and the tank 71.

[0156] The check valve 77A allows flow from the regulating accumulator 41 to the cylinder 73 and prohibits flow to the opposite side. In addition, the check valve 77A prohibits flow in both directions when the pilot pressure is introduced. The check valve 77B allows flow from the cylinder 73 to the tank 71 and prohibits flow in the opposite side. In addition, the check valve 77B prohibits flow in both directions when the pilot pressure is introduced.

[0157] The check valve 77C allows the flow from the tank 71 to the cylinder 73 and prohibits the flow to the opposite side. In addition, the check valve 77C prohibits the flow of both sides when the pilot pressure is introduced. The check valve 77D allows the flow from the cylinder 73 to the regulating accumulator 41 and prohibits the flow to the opposite side. In addition, the check valve 77D prohibits the flow of both sides when the pilot pressure is introduced.

[0158] When the gas is discharged from the regulating accumulator 41 to the tank 71, a pilot pressure is introduced to the check valves 77C and 77D. Then, when the piston 73b of the cylinder 73 moves downward in the figure, the gas in the regulating accumulator 41 is sucked into the cylinder 73 via the check valve 77A. Next, when the piston 73b moves upward in the figure, the gas is sent from the cylinder 73 to the tank 71 via the check valve 77B. This operation can be performed as many times as necessary and sufficient.

[0159] When gas is supplied from the tank 71 to the regulating accumulator 41, a pilot pressure is introduced to the check valves 77A and 77B. Then, when the piston 73b of the cylinder 73 moves downward in the figure, the gas in the tank 71 is sucked into the cylinder 73 via the check valve 77C. Next, when the piston 73b moves upward in the figure, gas is sent from the cylinder 73 to the regulating accumulator 41 via the check valve 77D. This operation can be performed as many times as necessary and sufficient.

[0160] In addition, when the gas in the regulating accumulator 41 is discharged to the tank 71, when the pressure of the tank 71 reaches a predetermined upper limit pressure, the tank 71 can be replaced. Similarly, when the gas in the tank 71 is supplied to the regulating accumulator 41, when the pressure of the tank 71 reaches a predetermined lower limit pressure, the tank 71 can be replaced.

[0161] The above structure can be appropriately embodied or variously modified. For example, a transmission mechanism such as a ball screw mechanism can be provided between the motor 75 and the piston 73b. When the gas in the regulating accumulator 41 is discharged to the tank 71, if the pressure of the regulating accumulator 41 is higher than the pressure of the tank 71, the cylinder 73 may not be used, and the gas in the regulating accumulator 41 may be discharged to the tank 71 only by the pressure difference between the two. On the contrary, when the gas in the tank 71 is supplied to the regulating accumulator 41, if the pressure of the tank 71 is higher than the pressure of the regulating accumulator 41, the cylinder 73 may not be used, and the gas supply from the tank 71 to the regulating accumulator 41 may be performed only by the pressure difference between the two.

[0162] (1.5. Operation of the injection device)

[0163] (1.5.1. Overview of injection device operation)

[0164] Figure 4 (a)~ Figure 5 (b) is a schematic diagram for explaining the operation of the injection device 9 when decompression is performed, which is equivalent to Figure 2 But here, as already mentioned, Figure 2 Differently, as the cylinder member 31 of the injection cylinder 27, a mode in which the diameter of the small-diameter cylinder portion 31x of the booster cylinder portion 31f is smaller than the diameter of the injection cylinder portion 31e is exemplified. Figure 4 (a) Enter in sequence Figure 5 (b).

[0165] Figure 4 (a) shows the state before the injection starts. In this state, the injection valve 43 and the regulating valve 45 are closed (in the state of the left rectangle in the figure representing each valve). The rod side valve 49 is closed, for example, by introducing a pilot pressure. The injection piston 33 and the booster piston 35 are respectively located at their respective retreat limits. The retreat limit is, for example, a position where the piston abuts (engages) a stopper (for example, the rear end of each cylinder part) of the cylinder member 31 from the front to the rear and stops.

[0166] Figure 4(b) represents the state when injection is performed. When the prescribed injection start condition is met, the control device 15 opens the injection valve 43 (becoming the state of the rectangle on the right side of the figure representing the injection valve 43). As a result, as shown by arrow a1, the working fluid is supplied from the injection accumulator 39 to the head side chamber 31h. Then, as shown by arrow a3, the injection piston 33 (as well as the piston rod 37 and the plunger 23 not shown here) advances. The working fluid in the rod side chamber 31r, which has a reduced volume as the injection piston 33 advances, is discharged to the tank 47 via the rod side valve 49 that stops the introduction of the pilot pressure, as shown by arrow a2.

[0167] Figure 5 (a) shows the state when the injection is completed. The control of the control device 15 at this time can be basically (except for details) the same as Figure 4 (b) is the same. The injection piston 33 is located at Figure 4 (b) The molten liquid (not shown) is substantially filled in the space 107. As shown by arrow a4, Figure 4 As indicated by the shorter arrow a3 in (b), the plunger 23 (injection piston 33) receives the reaction force from the melt and decelerates. As a result, the pressure in the head side chamber 31h rises (approaching the pressure of the injection accumulator 39 in another viewpoint).

[0168] Figure 5 (b) indicates a state of decompression. When the prescribed injection completion condition (in other words, decompression start condition) is satisfied, the control device 15 closes the injection valve 43 (becoming the state on the left side of the figure representing the injection valve 43). In addition, the control device 15 opens the regulating valve 45 at approximately the same time as the time of closing the injection valve 43 (becoming the state on the right side of the figure representing the regulating valve 45). In addition, the pressure of the head side chamber 31h at this time is approximately equal to or lower than the pressure of the injection accumulator 39.

[0169] As shown by arrow a5, even if the injection valve 43 is closed, the injection piston 33 moves forward due to inertia. As a result, the pressure in the head side chamber 31h decreases. Furthermore, the booster piston 35 moves forward. At this time, as shown by arrow a8, the working fluid is replenished from the regulating accumulator 41 to the rear side chamber 31b.

[0170] Then, the injection piston 33 stops due to the reaction force from the molten liquid. As a result, the working fluid in the head side chamber 31h cannot move forward, and the pressure in the head side chamber 31h becomes uniform. In addition, for example, the pressure in the head side chamber 31h rises due to the force from the molten liquid whose pressure rises due to the inertial force from the plunger 23.

[0171] At this time, as shown by arrow a7, the booster piston 35 retreats due to the pressure of the head side chamber 31h. As shown by arrow a9, the regulating accumulator 41 absorbs the pressure of the rear side chamber 31b that is about to rise due to the retreat of the booster piston 35. Then, the booster piston 35 stops at a position where the pressure of the head side chamber 31h and the pressure of the rear side chamber 31b (in other words, the pressure of the regulating accumulator 41) are balanced.

[0172] Through such an action, the pressure applied by the plunger 23 to the molten liquid after injection is reduced. Specifically, for example, as the booster piston 35 retreats, the pressure applied by the plunger 23 to the molten liquid is reduced. Moreover, the pressure (set pressure) applied by the plunger 23 to the molten liquid during pressure holding is determined by the pressure of the adjustment accumulator 41 (more precisely, the pressure of the adjustment accumulator 41 when the booster piston 35 stops), and the diameters of the large-diameter piston 35y, the small-diameter piston 35x, the injection piston 35x, and the plunger piece 23a.

[0173] In addition, the above-mentioned operation may be modified appropriately.

[0174] For example, in the illustrated example, the booster piston 35 is located at the retracted limit before the injection is completed. However, the booster piston 35 may be located at the forward limit before the injection is completed, or may be located between the forward limit and the retracted limit. Fig.13 This will be described later.

[0175] In addition, the timing of opening the regulating valve 45 may be much earlier than the timing of closing the injection valve 43 (for example, at the start of injection). Even in this case, the pressure of the regulating accumulator 41 is lower than the first pressure (the value obtained by converting the pressure of the injection accumulator 39 into the pressure of the rear chamber 31b) described above, so theoretically, the same operation as the example shown in the figure can be achieved.

[0176] In addition, the timing of opening the regulating valve 45 may be after the timing of closing the injection valve 43. However, as shown in the example shown in the figure, in a method in which the boosting piston 35 is located at the retreat limit when the injection valve 43 is closed, in order to advance the boosting piston 35 and replenish the working fluid as described with reference to arrows a6 and a8 after the injection valve 43 is closed, the regulating valve 45 is opened before the injection piston 33 completely stops.

[0177] In addition, the regulating valve 45 may be closed before the boosting piston 35 retreats to a position where the force generated by the hydraulic pressure of the head side chamber 31h and the force generated by the hydraulic pressure of the rear side chamber 31b are balanced. In this case, in theory, any pressure between the pressure obtained by converting the pressure of the injection accumulator 39 into the pressure applied to the melt by the plunger 23 (in other words, the pressure of the melt when the injection is completed) and the pressure obtained by converting the pressure of the regulating accumulator 41 into the pressure applied to the melt by the plunger 23 (in other words, the set pressure when the regulating valve 45 is not closed) can be used as the set pressure.

[0178] The operation of the injection device 9 when the pressure is increased instead of the pressure reduction can be the same as the operation of the known injection device. In addition, except that the pressure of the accumulator 41 is adjusted to be higher than the first pressure, the same valve control as the valve control when the pressure is reduced can be performed. In this case, the pressure increasing piston 35 does not generate a reference Figure 5 (b) The movement described is not to simply move forward. Then, the pressure is increased.

[0179] The set pressure (pressure during pressure maintenance) reached by the pressure applied by the plunger 23 to the melt by the pressure boost is determined, for example, by the pressure of the adjustment accumulator 41 (more precisely, the pressure of the adjustment accumulator 41 when the boost piston 35 stops) and the diameters of various components, as in the case of the pressure reduction. However, as in the case of the pressure reduction, the adjustment valve 45 may be closed before the boost piston 35 stops. In this case, in theory, any pressure between the pressure after the pressure of the injection accumulator 39 is converted into the pressure applied by the plunger 23 to the melt (in other words, the pressure of the melt when the injection is completed) and the pressure after the pressure of the adjustment accumulator 41 is converted into the pressure applied by the plunger 23 to the melt (in other words, the set pressure when the adjustment valve 45 is not closed) can be used as the set pressure.

[0180] In either case of reducing or increasing the pressure, the discharge of the working fluid from the rod side chamber 31r can be prohibited at an appropriate time. Thus, the pressure in the rod side chamber 31r can be different from the tank pressure, and a force determined by the pressure in the rod side chamber 31r and the pressure in the head side chamber 31h (and the diameters of the injection piston 33 and the piston rod 37) can be applied to the plunger 23.

[0181] As described above, the set pressure (pressure during pressure maintenance) may also be determined based on the time to close the regulating valve 45 after the start of pressure reduction or pressure increase, and / or the time to prohibit the discharge of the working fluid from the rod side chamber 31r. However, in the description of the embodiments, for convenience, a method in which the set pressure is determined by adjusting the pressure of the accumulator 41 without performing such an operation is sometimes used as an example, and sometimes, without special description, the description is based on this method.

[0182] (1.5.2. Examples of speed and pressure changes)

[0183] Figure 6 1 is a diagram showing an example of the time-dependent change in the speed (injection speed) of the plunger 23 and the pressure applied to the melt by the plunger 23. In the following description, for convenience, the pressure applied to the melt by the plunger 23 may be referred to as injection pressure.

[0184] In this figure, the horizontal axis represents time t, and the closer to the right, the later the time. The vertical axis on the left represents speed V, and the speed is higher as it goes up. The vertical axis on the right represents pressure P, and the pressure is higher as it goes up.

[0185] Line LnV shows the time-dependent change of injection speed. Lines Ln0, Ln1 and Ln2 show the time-dependent change of injection pressure. Line Ln0 shows the pressure change of the comparative example. Line Ln1 shows the pressure change when decompression is performed in the injection device 9 of the present embodiment. Line Ln2 shows the pressure change when pressurization is performed in the injection device 9 of the present embodiment.

[0186] The injection device 9 performs, for example, low-speed injection (time t0 to t1) and high-speed injection (time t1 to t2) in sequence. After that, the injection device 9 performs pressure reduction or pressure increase (time t3 to time t4), and then performs pressure maintenance (time t4 to t5). That is, as shown by line LnV, the die-casting machine 1 performs injection at a relatively low speed (speed V) in the initial stage of injection from the viewpoint of preventing the molten liquid from being entrained with air. L ) to advance the plunger 23. Next, as shown by line LnV, the die casting machine 1 is operated at a relatively high speed (speed V) from the viewpoint of filling the molten liquid without delaying the solidification of the molten liquid. H ) high-speed injection that advances the plunger 23. Next, as shown by lines Ln0 to Ln2, from the viewpoint of eliminating shrinkage cavities, the die casting machine 1 performs pressure reduction or pressure increase while maintaining pressure to apply appropriate pressure to the molten liquid. When maintaining pressure, the set pressure Pc1 or Pc2 obtained by pressure reduction or pressure increase is maintained.

[0187] The injection pressure is relatively low during low-speed injection (time t0-t1). Figure 6 For convenience, the injection pressure during low-speed injection is omitted because it is extremely small. After that, when high-speed injection begins (time t1), the injection pressure rises. Furthermore, when the filling of the molten liquid is almost completed (time t2), the molten liquid has nowhere to go, so the injection pressure rises sharply. At this time, as shown by the line Ln0 of the comparative example, the so-called impact pressure may sometimes be generated.

[0188] In addition, the speed V of the low-speed injection L , high speed injection speed V H, the switching conditions from low-speed injection to high-speed injection, the injection speed control method, etc. can be the same as those of the known injection device. For example, the speed V L Less than 1m / s. High-speed injection speed V H The switching from low-speed injection to high-speed injection can be performed roughly when the molten liquid reaches the gate of the metal mold 101. More specifically, for example, it can be triggered by the position sensor that detects the position of the plunger 23 reaching a specified position. The speed control can be achieved by the above-mentioned inlet throttling circuit or outlet throttling circuit. At this time, feedback control based on the detected position (speed) of the plunger 23 can also be performed.

[0189] When decompression is performed in the injection device 9, as described above, the injection valve 43 can be closed before the plunger 23 stops. In this way, the impact pressure can be reduced. In addition, in the injection device 9, it is not limited to whether decompression or pressurization is performed, and the impact pressure can also be reduced by using the pressurizing device 13. Specifically, before the filling of the molten liquid is substantially completed, the pressurizing member 61 is placed at the forward limit by applying hydraulic pressure to the pressurizing cylinder 63 using the accumulator. When the molten liquid reaches the pressurizing member 61, the pressurizing member 61 pushed by the molten liquid retreats, and the hydraulic pressure of the pressurizing cylinder 63 at this time is absorbed by the accumulator.

[0190] When the injection device 9 is depressurized, the time to close the injection valve 43 and / or the time to open the adjustment valve 45 may be, for example, the injection speed V from the injection speed of the high-speed injection to the injection speed V of the high-speed injection. H The appropriate time from the start of the lowering to the stop of the plunger 23. Fig.13 As described above, according to a specific method, the injection valve 43 may be closed after the injection speed becomes 0, or the adjustment valve 45 may be opened.

[0191] When decompression is performed in the injection device 9, the conditions for closing the injection valve 43 and / or opening the regulating valve 45 (in other words, triggers, sometimes referred to as "injection completion conditions" for convenience) can also be appropriately set. For example, the injection completion conditions can also be the same as the conditions when pressurization is started in the existing injection device. For example, the injection completion conditions can be: the position sensor detects that the plunger 23 has reached a specified position, the pressure sensor detects that the injection pressure has reached (risen) a specified pressure, and / or detects that the molten liquid has reached a specified position. As sensors for detecting that the molten liquid has reached a specified position, for example, there can be listed: a power sensor, a temperature sensor, or a pressure sensor. Furthermore, in the case of absorbing the impact pressure using the pressurizing device 13 as described above, the molten liquid can also be detected to have reached a specified position by detecting the retreat of the pressurizing component 61.

[0192] During decompression, the moment t3 when the injection pressure reaches the peak is, for example, the moment when the plunger 23 (injection piston 33) stops after the injection valve 43 is closed. The magnitude of the pressure at this time is, for example, less than the magnitude after the pressure of the injection accumulator 39 is converted into the injection pressure. Afterwards, when the booster piston 35 begins to retreat, the injection pressure begins to decrease. Then, when the retreat of the booster piston 35 stops (time t4), the decrease in injection pressure stops, and the injection pressure becomes the set pressure Pc1. As described above, the set pressure Pc1 is roughly the magnitude after the pressure of the adjustment accumulator 41 is converted into the injection pressure. In addition, the above is nothing more than a theoretical thing that ignores the details. Therefore, for example, in reality (strictly speaking), the actions of the plunger 23 and the booster piston 35 are not limited to being linked to the changes in the injection pressure as described above.

[0193] During decompression, the flow of the working fluid can be appropriately controlled to obtain a desired decompression curve (line Ln1). For example, the opening of the regulating valve 45 can be adjusted to a preset appropriate size, or feedback control can be performed to change the opening of the regulating valve 45 in real time.

[0194] The operation when the injection device 9 performs pressurization may be the same as the operation when the injection device 9 performs pressurization as described above. Figure 6 FIG. 2 shows the pressure change when the impact pressure is absorbed by the pressurizing device 13 .

[0195] exist Figure 6 In FIG. 1 , line Ln1 can be regarded as the pressure change when the set pressure Pc1 is set to the lowest. Similarly, line Ln2 can also be regarded as the pressure change when the set pressure Pc2 is set to the highest. In this case, the injection device 9 can adjust the set pressure within a range R1 between the line Ln1 and the line Ln2.

[0196] (1.5.3. Example of control flow chart)

[0197] Figure 7 This is a flowchart showing an example of the procedure of the process executed by the controller 15 in order to realize the operation described above.

[0198] For example, this process is started when the die casting machine 1 starts to operate. Here, for convenience, the steps for repeated molding cycles are omitted, and only the steps for performing one molding cycle are extracted and shown. In addition, only the steps related to the operation of the injection device 9 are extracted, and the steps related to other devices such as the mold clamping device 7 are omitted.

[0199] In step ST1, the control device 15 receives input of forming conditions. The forming conditions may include, for example, injection speed and injection pressure, as in the conventional die casting machine. In addition, the forming conditions may include conditions related to whether to perform decompression or pressurization. The input is performed, for example, by an operator operating the input device 17.

[0200] In step ST2, the control device 15 determines whether the setting of the decompression or pressurization set in step ST1 is different from the previously executed forming cycle. That is, the control device 15 determines whether the switching of decompression and pressurization is instructed. The controller 15 enters step ST3 when the determination is positive, and skips step ST3 and enters step ST4 when the determination is negative.

[0201] In step ST3, the control device 15 controls the ACC pressure adjustment unit 53 so that the pressure of the adjustment accumulator 41 becomes a value corresponding to the pressure reduction or pressure increase after the switching. In addition, the operation at this time further allows the pressure of the adjustment accumulator 41 to be a value corresponding to the specific value of the set pressure Pc1 or Pc2 set in step ST1. In this case, step ST3 can be executed regardless of whether the switching between pressure reduction and pressure increase is performed.

[0202] In step ST4, the control device 15 determines whether the prescribed injection start condition is satisfied. If it is determined that the condition is satisfied, the control device 15 controls the various components of the injection device 9 to start the injection. The operation (control) at this time is as described in reference to Figure 4 The injection start condition may be, for example, that the fixed mold 103 and the movable mold 105 are clamped and information indicating that the molten liquid has been supplied to the sleeve 21 is obtained.

[0203] In step ST5, the control device 15 determines whether the condition for completing the injection (injection completion condition) is satisfied. Figure 6 As described above, the control device 15 proceeds to step ST6 when a positive determination is made, and repeats step ST5 (continuation of injection) when a negative determination is made.

[0204] In step ST6, the control device 15 controls each component to perform the action set by step ST1 in decompression and pressure increase. Figure 5 (b) As already explained.

[0205] In step ST7, the control device 15 determines whether the injection pressure has reached the set pressure Pc1 or Pc2 set in step ST1. Then, the control device 15 proceeds to step ST8 when the determination is positive, and repeats step ST7 (continuing pressure reduction or pressure increase) when the determination is negative.

[0206] In step ST8, the control device 15 controls each part of the injection device 9 to maintain the pressure. However, the pressure can be maintained by continuing the operation during decompression or pressure increase. In this case, steps ST7 and ST8 are not required.

[0207] Afterwards, although not particularly shown in the figure, when a predetermined pressure holding completion condition is satisfied, the control device 15 controls each part of the injection device 9 to end the pressure holding. For example, the injection device 9 may supply working fluid to the rod side chamber 31r through a pump (not shown) to retract the injection piston 33 and further retract the booster piston 35. The pressure holding completion condition may be the same as that in a known injection device, for example, a predetermined time may have passed since an appropriate time such as the injection start time or the injection completion time.

[0208] After that, the control device 15 ends the illustrated process. In addition, in the process of repeated forming cycles, for example, after step ST8, a step of determining whether the forming cycle has been repeated the number of times set in step ST1 may be added. Then, the control device 15 ends the illustrated process in the case of a positive determination, and returns to step ST4 in the case of a negative determination.

[0209] In step ST1, it is explained that the conditions related to decompression and pressurization can be set. The setting of the conditions can be performed, for example, by selecting the operation of decompression and pressurization. Or, for example, the setting of the conditions can also be performed simply by receiving an input operation of the value of the set pressure (Pc1 or Pc2). That is, it can be set whether to perform decompression or pressurization based on whether the value input as the set pressure is a low pressure or a high pressure relative to the pressure when the injection is completed. In this case, the control device 15 can make a determination as in step ST2, or it can not make such a determination, and adjust the pressure of the adjustment accumulator 41 to a pressure corresponding to the set pressure set in step ST1.

[0210] Regarding step ST1, a conventional die-casting machine cannot set a value that does not conform to the size of the assumed action (pressurization) as the set pressure Pc2. For example, if a value lower than the pressure after the pressure of the injection accumulator 39 (or the accumulator for pressurization) is converted into the injection pressure is input as the set pressure Pc2, pressurization cannot be performed. In this case, for example, a warning is issued via the display device 19 or a forming cycle based on such a value is not performed. On the other hand, the control device 15 of the present embodiment allows such a value to be set as the set pressure (Pc1). In other words, the control device 15 performs a forming cycle based on such a value.

[0211] (1.6. Summary of the First Implementation Method)

[0212] As described above, the injection device 9 of the present embodiment performs injection and pressure holding. Injection is the action of pushing the molding material (molten liquid) in the sleeve 21 into the mold (the space 107 of the metal mold 101) by the plunger 23. Pressure holding is the action of applying a predetermined set pressure (Pc1 or Pc2) to the molten liquid filled in the metal mold 101 for a certain period of time by the plunger 23. The injection device 9 has a driving unit 25 connected to the plunger 23. The driving unit 25 applies a driving force to the plunger 23 for reducing the pressure applied by the plunger 23 to the molten liquid filled in the metal mold 101 to the set pressure Pc1.

[0213] In another aspect, the manufacturing method of the molded product (die casting product) of the embodiment includes an injection step (ST4) and a pressure holding step (ST8). The injection step is a step of pushing the molding material (molten liquid) in the sleeve 21 into the mold (the space 107 of the metal mold 101) by the plunger 23. The pressure holding step is a step of applying a predetermined set pressure (Pc1 or Pc2) to the molten liquid filled in the metal mold 101 for a certain period of time by the plunger 23. The manufacturing method also includes a decompression step (ST6) of reducing the pressure applied by the plunger 23 to the molten liquid filled in the metal mold 101 by the injection step and reaching the set pressure Pc1.

[0214] Therefore, for example, as described in the gist of the embodiment, the molten metal is filled into the mold 101 at a relatively high speed without delaying the solidification of the molten metal, and at the same time, the possibility of burrs being generated due to pressurization performed after filling is reduced.

[0215] In addition, the decompression mentioned here means that "the pressure applied by the plunger to the molding material filled in the mold decreases and reaches the set pressure (pressure during pressure holding)", so it is different from Figure 6 The pressure drop after the impact pressure occurs in the injection device of the comparative example shown by the line Ln0 is different. This is because, in the comparative example, the pressure applied by the plunger to the molding material decreases after the impact pressure is generated, and then increases by pressurization, and reaches the set pressure Pc2 for holding pressure at the same time.

[0216] The driving part 25 may include: an injection cylinder 27 connected to the plunger 23, and a hydraulic device 29 for applying hydraulic pressure to the injection cylinder 27. The injection cylinder 27 may include: a piston rod 37 connected to the rear of the plunger 23, an injection piston 33 fixed to the rear of the piston rod 37, and an injection cylinder part 31e that accommodates the injection piston 33 in a slidable manner. The interior of the injection cylinder part 31e may be divided into a rod side chamber 31r in the front and a head side chamber 31h in the rear by the injection piston 33. The hydraulic device 29 may include a pressure regulating part 40 (symbol ) for reducing the pressure of the head side chamber 31h when decompressing. Figure 2 ).

[0217] In this case, for example, the injection can be performed by supplying the working fluid to the head side chamber 31h. The injection speed at this time is easy to achieve a high speed compared with the injection speed in the method where the drive unit 25 is an electric type (this method is also included in the technology of the present invention). On the other hand, since the injection speed is high, the pressure applied to the molten liquid by the plunger 23 is easy to increase, so the decompression effect is effectively exerted.

[0218] The pressure regulating unit 40 may include a regulating accumulator 41 for absorbing the hydraulic pressure of the injection cylinder 27 when reducing the pressure.

[0219] In this case, for example, it is easier to reduce the hydraulic pressure to an arbitrary level than in a method of releasing the hydraulic pressure of the injection cylinder 2 to the tank 47 (this method is also included in the technology of the present invention). For example, when the working fluid of the rear chamber 31b is released to the tank 47 for decompression, it is necessary to close the valve between the rear chamber 31b and the tank 47 at an appropriate time in order to prevent the pressure of the rear chamber 31b from dropping excessively. However, in this embodiment, this necessity can be reduced. In addition, compared with a method of releasing the hydraulic pressure to the tank 47, it is also possible to expect an effect of relieving a sudden change in the pressure of the rear chamber 31b (and thus the injection pressure).

[0220] The injection cylinder 27 may include: a small-diameter cylinder portion 31x, a large-diameter cylinder portion 31y, a small-diameter piston 35x, and a large-diameter piston 35y. The small-diameter cylinder portion 31x may be connected to the head side chamber 31h. The large-diameter cylinder portion 31y may be connected in series with the small-diameter cylinder portion 31x, and the diameter may be larger than that of the small-diameter cylinder portion 31x. The small-diameter piston 35x may be slidably received in the small-diameter cylinder portion 31x. The large-diameter piston 35y may be fixed in series to the small-diameter piston 35x, may be slidably received in the large-diameter cylinder portion 31y, or the large-diameter cylinder portion 31y may be divided into a front side chamber 31a on the side of the small-diameter cylinder portion 31x and a rear side chamber 31b on the opposite side thereof. The regulating accumulator 41 may be connected to the rear side chamber 31b.

[0221] In this case, for example, the pressure of the regulating accumulator 41 is increased and applied to the head side chamber 31h, so that the pressure of the regulating accumulator 41 when achieving the desired set pressure (for example, the set pressure Pc1 when reducing pressure) can be lowered compared to the second embodiment described later. The pressure of the regulating accumulator 41 is set to an upper limit value for safety. On the other hand, it is easy to lower the pressure of the regulating accumulator 41. Therefore, for example, it is easy to set the value of the set pressure within a wider range compared to the second embodiment described later. More specifically, for example, it is easy to expand Figure 6 Range R1 shown.

[0222] The hydraulic device 29 may include an injection accumulator 39 for supplying working fluid to the head side chamber 31h during injection. The pressure of the regulating accumulator 41 may be lower than the first pressure obtained by multiplying the pressure of the injection accumulator 39 by the square of the ratio of the diameter of the small diameter piston 35x divided by the diameter of the large diameter piston 35y.

[0223] In this case, for example, since the working fluid is supplied from the injection accumulator 39 to the head side chamber 31h, high-speed injection is easier than in an injection device in which the piston rod 37 is driven by a motor (a hybrid injection device combining an electric type and a hydraulic type, which is also included in the technology of the present invention). In addition, for example, as can be understood from the above description, by adjusting the pressure of the accumulator 41 to be lower than the first pressure, decompression can be reliably achieved.

[0224] The driving unit 25 can selectively perform decompression and pressurization to increase the pressure applied by the plunger 23 to the molten liquid filled in the metal mold 101 to reach the set pressure Pc2.

[0225] In this case, for example, not only decompression but also pressurization can be performed, so the range of molding conditions is expanded. As a result, it is easy to set appropriate molding conditions corresponding to the size of the metal mold 101 and the shape of the space 107.

[0226] The injection device 9 may include an ACC pressure regulating unit 53 that regulates the pressure of the accumulator 41 within a pressure range from a pressure lower than the first pressure to a pressure higher than the first pressure.

[0227] In this case, for example, it is possible to easily switch between decompression and pressurization. That is, it is also possible not to use a separate device different from the injection device to adjust the pressure of the adjustment accumulator 41. In addition, for example, when the preferred set pressure is close to the value obtained by converting the first pressure into the injection pressure, the switching frequency between decompression and pressurization may become high when searching for the preferred molding conditions through trial operation. It is also easy to deal with this situation.

[0228] The control device 15 may include a control device 15 that controls the drive unit 25 to reduce the pressure.

[0229] In this case, for example, compared with a method of passively reducing pressure (which is also included in the technology of the present invention), it is practical to realize the reduced pressure. From another point of view, the design freedom of the injection device 9 is improved, and the molding conditions can be easily changed. As a method of passively reducing pressure, for example, a structure in which a valve is opened and closed in conjunction with the movement of the plunger 23 and a structure using a relief valve are listed.

[0230] The injection device 9 may include an input device 17 for receiving an operation for setting a set pressure, and a control device 15 for controlling the drive unit 25 based on the set pressure set by the operation of the input device 17. The drive unit 25 may include an injection cylinder 27 connected to the plunger 23, and a hydraulic device 29 for applying hydraulic pressure to the injection cylinder 27. The hydraulic device 29 may include an injection accumulator 39 for supplying working fluid to the injection cylinder 27 during injection. The control device 15 may allow a pressure lower than the pressure obtained by converting the pressure of the injection accumulator 39 into the pressure applied to the melt by the plunger 23 to be set as the set pressure Pc1.

[0231] In this case, for example, injection can be performed at a relatively high pressure from the injection accumulator 39 and then decompressed. In addition, as described above, in the conventional injection device that only performs pressurization, it is generally not allowed to set such a set pressure.

[0232] (2. Second Embodiment)

[0233] Figure 8 (a)~ Fig. 9 (b) is a schematic diagram showing the structure and operation of the injection device 209 of the second embodiment. These figures correspond to those of the first embodiment. Figure 4 (a)~ Figure 5 (b).

[0234] In short, the injection device 209 is structured such that the booster injection cylinder 27 in the first embodiment is replaced with a single-tube injection cylinder 227. In short, the injection cylinder 227 is structured such that the booster cylinder 31f and the booster piston 35 are removed from the booster injection cylinder 27.

[0235] As the injection cylinder 27 is replaced by the injection cylinder 227, the pressure accumulator 41 is adjusted to be connected to the head side chamber 31h. In addition, the flow path and valves not shown in the figure may also be different from the first embodiment as the injection cylinder 27 is replaced by the injection cylinder 227. In addition, the parts not shown in the figure may be the same as the known structure, so the description thereof is omitted.

[0236] The action of the injection device 209 is Figure 8 (a) Enter in sequence Fig. 9 (b). The details are as follows.

[0237] In addition to the actions associated with the booster piston 35, Figure 8 (a) Figure 8 (b) and Fig. 9 The operation of (a) is similar to that of the first embodiment. Figure 4 (a) Figure 4 (b) and Figure 5 (a) has the same action. Therefore, Figure 4(a) Figure 4 (b) and Figure 5 The description of the action of (a) may be appropriately cited in Figure 8 (a) Figure 8 (b) and Fig. 9 (a) Action.

[0238] Fig. 9 (b) shows a state of decompression, which is different from the first embodiment. Figure 5 (b) Correspondence: Similar to the first embodiment, when the predetermined injection completion condition is satisfied, the control device 15 closes the injection valve 43 and opens the regulating valve 45 .

[0239] As shown by arrow a5, even if the injection valve 43 is closed, the injection piston 33 (plunger 23) moves forward due to inertia. As a result, the pressure of the head side chamber 31h decreases. At this time, as shown by arrow a21, the working fluid is replenished from the regulating accumulator 41 to the head side chamber 31h.

[0240] Then, the injection piston 33 (plunger 23) stops due to the reaction force received from the molten liquid. As a result, the working fluid in the head side chamber 31h cannot move forward, and the pressure of the working fluid in the head side chamber 31h becomes uniform. In addition, for example, the pressure of the head side chamber 31h rises due to the force from the molten liquid whose pressure rises due to the inertial force from the plunger 23. The regulating accumulator 41 absorbs the pressure of the head side chamber 31h until the pressure of the head side chamber 31h is equal to the pressure of the regulating accumulator 41.

[0241] By such an action, the pressure applied by the plunger 23 to the molten liquid after injection is reduced. Specifically, after the plunger 23 stops, as the pressure of the head side chamber 31h decreases, the pressure applied by the plunger 23 to the molten liquid decreases. Moreover, the pressure (set pressure Pc1) applied by the plunger 23 to the molten liquid during pressure maintenance is determined by the pressure of the adjustment accumulator 41 (more precisely, the pressure of the adjustment accumulator 41 when the pressure reduction of the head side chamber 31h is completed) and the diameters of various components.

[0242] As can be understood from the above description, in addition, from the case where the boosting piston 35 is not provided, the pressure of the adjustment accumulator 41 when reducing pressure is performed is different from the first embodiment, and is not lower than the first pressure, but is, for example, lower than the pressure of the injection accumulator 41. Thus, for example, even if the pressure of the head side chamber 31h rises to the same level as the pressure of the injection accumulator 39 when the injection is completed, it is possible to reduce pressure.

[0243] In the second embodiment, unlike the first embodiment, the action of advancing the booster piston 35 at the retreat limit is not required. Therefore, the injection valve 43 does not need to be closed before the injection piston 33 stops. In other words, the injection valve 43 can be closed after the injection piston 33 stops. In addition, for the same reason, if the viewpoint of quickly obtaining the set pressure Pc1 is ignored, the timing of opening the regulating valve 45 can also be delayed a lot relative to the timing of closing the injection valve 43.

[0244] In the first embodiment, even if the regulating valve 45 is opened long before the injection is completed (for example, when the injection starts), since the booster piston 35 is at the retreat limit, the possibility that the pressure of the head side chamber 31h is absorbed by the regulating accumulator 41 before the injection is completed is reduced. Unlike the first embodiment, in this embodiment, the regulating valve 45 is usually opened at the same time as the time when the plunger 23 stops and / or the time when the injection valve 43 is closed. However, the regulating valve 45 may be opened earlier than the above time, and the regulating accumulator 41 is used to reduce the injection speed and / or ease the sharp rise of the injection pressure.

[0245] As described above, when the pressure of the regulating accumulator 41 is lower than the pressure of the injection accumulator 39, in more detail, the pressures of the injection accumulator 39 and the regulating accumulator 41 may be set to the pressures at the time of injection completion (for example, when the injection valve 43 is closed) as in the first embodiment. However, the pressure of the regulating accumulator 41, for example, the highest pressure in the molding cycle, may be used for comparison. That is, the condition that the pressure of the regulating accumulator 41 is lower than the pressure of the injection accumulator 39 may be more stringent.

[0246] The injection device 209 may be configured to be capable of not only reducing pressure but also increasing pressure, similarly to the first embodiment. The structure and operation in this case may be the same as those known in the art, except that the regulating accumulator 41 is used as a pressure increasing accumulator.

[0247] When the pressure accumulator 41 is used for pressurization, for example, the pressure is higher than the pressure of the injection accumulator 39. In addition, for example, as in the case of decompression, the pressure for comparison may be the pressure at the time of injection completion. However, the pressure of the injection accumulator 39 may also be the pressure before the injection is completed (in other words, before the pressure drops). That is, the condition that the pressure of the adjustment accumulator 41 is higher than the pressure of the injection accumulator 39 may be more stringent. In addition, regarding the pressure of the adjustment accumulator 41, the pressure at the time of pressurization (and then pressure maintenance) completion (the lowest pressure in the molding cycle) may also be used for comparison.

[0248] The injection device 209 may also be provided with an ACC pressure regulating unit 53 (see the first embodiment) that can achieve both pressure reduction and pressure increase to regulate the pressure of the regulating accumulator 41. However, as can be seen from the above description, unlike the first embodiment, the ACC pressure regulating unit 53 regulates the pressure of the regulating accumulator 41 within a range from a pressure lower than the pressure of the injection accumulator 39 to a pressure higher than the pressure of the injection accumulator 39.

[0249] As described above, in the second embodiment as well, the driving unit 25 (reference number to the first embodiment) applies a driving force to the plunger 23 to reduce the pressure applied by the plunger 23 to the molten liquid filled in the mold 101 to the set pressure Pc1. Therefore, the same effects as those of the first embodiment can be achieved.

[0250] As shown in this embodiment, the regulating accumulator 41 may communicate with the head side chamber 31h.

[0251] Even in this case, as in the first embodiment, the pressure of the injection cylinder 227 can be reduced by absorbing the pressure of the injection cylinder 227 with the regulating accumulator 41. Figure 6 ), the first embodiment is advantageous.

[0252] The hydraulic device 29 (refer to the first embodiment for the reference numerals) of the injection device 209 may include an injection accumulator 39 for supplying working fluid to the head chamber 31h during injection. The pressure of the regulating accumulator 41 may be lower than the pressure of the injection accumulator 39 .

[0253] In this case, for example, as described in the first embodiment, since the working fluid is supplied from the injection accumulator 39 to the head side chamber 31h, high-speed injection is easy compared to the injection device in which the piston rod 37 is driven by the motor. In addition, for example, as can be understood from the above description, by making the pressure of the adjustment accumulator 41 lower than the pressure of the injection accumulator 39, it is possible to reliably achieve decompression.

[0254] (3. Third Embodiment)

[0255] Fig.10 (a)~ Fig.11 (b) is a schematic diagram showing the structure and operation of the injection device 309 of the third embodiment. These figures correspond to those of the first embodiment. Figure 4 (a)~ Figure 5 (b).

[0256] In short, the structure of the injection device 309 is a structure in which the adjustment accumulator 41 is connected to the rod side chamber 31r instead of the head side chamber 31h in the injection device 209 of the second embodiment. And, by applying hydraulic pressure from the adjustment accumulator 41 to the rod side chamber 31r after the injection is completed, it is possible to reduce the force applied by the injection piston 33 to the plunger 23, and further reduce the pressure applied by the plunger 23 to the molten liquid. In addition, hereinafter, the structure (including the structure of the adjustment accumulator 41) that applies hydraulic pressure to the rod side chamber 31r for reducing pressure is sometimes referred to as the pressure regulating unit 340.

[0257] The structure of the hydraulic device 329 for realizing the above-mentioned operation may be various structures. In the example shown in the figure, it is as follows.

[0258] The hydraulic device 329 of the injection device 309 has a rod-side valve 349 that switches the connection destination of the rod-side chamber 31r between the tank 47 and the regulating accumulator 41. The rod-side valve 349 is composed of, for example, a 3-port 2-position (3-way 2-position) switching valve. In addition, the rod-side valve 349 connects the rod-side chamber 31r and the regulating accumulator 41 by the restoring force of the spring when the solenoid is not driven (becoming a rectangular state on the right side of the figure), and connects the rod-side chamber 31r and the tank 47 when the solenoid is driven (becoming a state on the left side of the figure).

[0259] The hydraulic device 329 is different from the first and second embodiments, for example, and is configured to control the forward speed (movement speed to the left side of the figure) of the injection piston 33 through an outlet throttling circuit. More specifically, for example, the rod side valve 349 has the function of a servo valve and the function of a flow control valve (for example, a flow regulating valve with pressure compensation). On the other hand, the injection valve 343 between the injection accumulator 39 and the head side chamber 31h is composed of a pilot-operated check valve. The check valve allows flow from the injection accumulator 39 to the head side chamber 31h and prohibits flow to the opposite side. In addition, the check valve prohibits flow on both sides when the pilot pressure is introduced. In addition, an inlet throttling circuit may be provided instead of the outlet throttling circuit or on its basis.

[0260] The action of the injection device 309 is Fig.10 (a) Enter in sequence Fig.11 (b). The details are as follows.

[0261] Fig.10 (a) shows the state before the injection starts, which is different from the first embodiment. Figure 4 (a) corresponds. The injection valve 343 and the regulating valve 345 are closed by the pilot pressure. The rod side valve 349 can be located at any position, but in the example shown in the figure, it is located at a position connecting the rod side chamber 31r and the tank 47. The injection piston 33 is located at the retreat limit.

[0262] Fig.10(b) shows the state when the injection is performed, which is different from the first embodiment. Figure 4 (b) corresponds. When the prescribed injection start condition is satisfied, the control device 15 stops introducing the pilot pressure and opens the injection valve 343. As a result, as shown by arrow a1, the working fluid is supplied from the injection accumulator 39 to the head side chamber 31h. Then, as shown by arrow a3, the injection piston 33 moves forward. The working fluid in the rod side chamber 31r, which has a reduced volume as the injection piston 33 moves forward, is discharged to the tank 47 via the rod side valve 349, as shown by arrow a2.

[0263] Fig.11 (a) shows the state when the injection is completed. The control of the control device 15 at this time can be basically (except for details) the same as Fig.10 (b) is the same. The injection piston 33 is located at Fig.10 (b). The molten liquid (not shown) is substantially filled in the space 107. As shown by arrow a4, Fig.10 As indicated by the shorter arrow a3 in (b), the plunger 23 (injection piston 33) receives the reaction force from the melt and decelerates. As a result, the pressure in the head side chamber 31h rises (approaching the pressure of the injection accumulator 39 in another viewpoint).

[0264] Fig.11 (b) shows a state of decompression. When the predetermined injection completion condition is satisfied, the control device 15 switches the rod side valve 349 to connect the rod side chamber 31r to the regulating accumulator 41, and stops the introduction of the pilot pressure to the regulating valve 345, and opens the regulating valve 345. As a result, as shown by arrows a31 and a32, the pressure of the regulating accumulator 41 is applied to the rod side chamber 31r, and the pressure is reduced.

[0265] In addition, for example, unlike when speed control is performed (from the start of injection to the completion of injection), the rod side valve 349 as a flow control valve can be fully opened. However, it is also possible to help achieve a desired pressure reduction curve by controlling the rod side valve 349 to open at an appropriate opening (see Figure 6 Line Ln1 in the figure).

[0266] Then, the injection piston 33 stops at a position where the force received from the molten liquid via the plunger 23, the force applied to the injection piston 33 by the pressure of the rod side chamber 31r (in other words, the pressure of the adjustment accumulator 41), and the force applied to the injection piston 33 by the pressure of the head side chamber 31h (in other words, the pressure of the injection accumulator 39) are balanced. The pressure applied to the molten liquid by the plunger 23 at this time becomes the set pressure Pc1.

[0267] The pressure of the adjustment accumulator 41 (more strictly speaking, the pressure before the hydraulic pressure is applied to the rod side chamber 31r) can be set to an appropriate value greater than the tank pressure. Theoretically, as long as the pressure of the adjustment accumulator 41 is not zero, the pressure of the head side chamber 31h will have the effect of reducing the force applied to the injection piston 33 forward to some extent through the pressure of the rod side chamber 31r. In addition, the pressure can be reduced.

[0268] For example, if an extreme case is taken into consideration, the pressure of the adjustment accumulator 41 may be lower (may be actually lower) than the pressure obtained by converting the pressure of the injection accumulator 39 into the pressure of the rod side chamber 31r (the pressure obtained by multiplying the pressure of the injection accumulator 39 by the value obtained by dividing the cross-sectional area of ​​the injection piston 33 by the value obtained by subtracting the cross-sectional area of ​​the piston rod 37 from the cross-sectional area of ​​the piston 33). Thus, for example, the set pressure Pc1 may be set to a value greater than 0.

[0269] Applying hydraulic pressure from the regulating accumulator 41 to the rod side chamber 31r (in the example shown, switching of the rod side valve 349 and opening of the regulating valve 345) may be performed before the plunger 23 stops, or may be performed when or after the plunger 23 stops. In the former case, the regulating accumulator 41 can help absorb the impact generated in the rod side chamber 31r when the plunger 23 stops due to the reaction force from the melt, for example.

[0270] In addition, the above-mentioned operation may be modified appropriately.

[0271] For example, the injection valve 343 may be closed at an appropriate time before the plunger 23 stops. That is, the injection valve 343 may be closed before the pressure of the head side chamber 31h rises to the pressure of the injection accumulator 39. In addition, for example, the injection valve 343 may be closed before the force received by the injection piston 33 from the molten liquid via the plunger 23, the force applied to the injection piston 33 by the pressure of the rod side chamber 31r, and the force applied to the injection piston 33 by the pressure of the injection accumulator 39 via the head side chamber 31h are balanced.

[0272] The application of hydraulic pressure from the regulating accumulator 41 to the rod side chamber 31r can be stopped at an appropriate time (for example, the regulating valve 345 can be closed at an appropriate time). That is, the application of hydraulic pressure is stopped before the force received by the injection piston 33 from the molten liquid via the plunger 23, the force applied to the injection piston 33 by the pressure of the regulating accumulator 41 via the rod side chamber 31r, and the force applied to the injection piston 33 by the pressure of the head side chamber 31h are balanced. In addition, it can be understood from this that the pressure of the regulating accumulator 41 can also be greater than the pressure obtained by converting the pressure of the injection accumulator 39 into the pressure of the rod side chamber 31r.

[0273] It is also possible to provide a boosting accumulator (refer to the adjusting accumulator 41 of the second embodiment) that is connected to the head side chamber 31h separately from the adjusting accumulator 41 that is connected to the rod side chamber 31r. In this way, both pressure reduction and pressure increase can be performed. In addition, instead of the single-tube injection cylinder 227, the adjusting accumulator 41 that is connected to the rod side chamber 31r can be applied to the boosting injection cylinder 27. Moreover, the working fluid can be supplied from the injection accumulator 39 or the boosting accumulator to the rear side chamber 31b. In this way, both pressure reduction and pressure increase can be performed.

[0274] As described above, in the third embodiment, the driving unit 25 (reference to the first embodiment for the symbols) also applies a driving force to the plunger 23 for reducing the pressure applied by the plunger 23 to the molten liquid filled in the metal mold 101 to the set pressure Pc1. Therefore, the same effects as those of the first embodiment can be achieved.

[0275] As shown in this embodiment, the driving unit 25 may include an injection cylinder 227 connected to the plunger 23, and a hydraulic device 329 for applying hydraulic pressure to the injection cylinder 227. The injection cylinder 227 may include a piston rod 37 connected to the rear of the plunger 23, an injection piston 33 fixed to the rear of the piston rod 37, and an injection cylinder portion 31e that slidably accommodates the injection piston 33. The interior of the injection cylinder portion 31e may be divided into a rod side chamber 31r at the front and a head side chamber 31h at the rear by the injection piston 33. The hydraulic device 329 may also include a pressure regulating portion 340 that increases the pressure of the rod side chamber 31r when decompressing.

[0276] In this case, for example, the injection can be performed by supplying the working fluid to the head side chamber 31h. The injection speed at this time is easier to achieve than the injection speed in the case where the drive unit 25 is an electric type (this method is also included in the technology of the present invention). On the other hand, since the injection speed is high, the pressure applied to the molten liquid by the plunger 23 is easy to increase, so the decompression effect is effectively exerted.

[0277] The pressure regulating unit 340 may include a regulating accumulator 41 for applying hydraulic pressure to the rod side chamber 31 r when reducing pressure.

[0278] In this case, for example, the pressure of the rod side chamber 31r can be rapidly increased. As a result, a desired pressure reduction curve can be easily obtained.

[0279] (4. Modifications)

[0280] (4.1. Modification of the Hydraulic Device of the Injection Device)

[0281] It has been explained that the specific structure of the hydraulic device (hydraulic circuit) for realizing the operation described in the embodiment can be various. Below, an example different from the above example is shown.

[0282] Fig.12 Schematic diagram showing a part of a hydraulic device of a modified example. Figure 8 corresponds to part of (a).

[0283] As shown in the figure, the injection valve 43A between the injection accumulator 39 and the head side chamber 31h (not shown here) can also be composed of a pilot check valve. The check valve allows flow from the injection accumulator 39 to the head side chamber 31h (below the figure) and prohibits flow to the opposite side. In addition, the check valve prohibits flow from both sides when the pilot pressure is introduced. Then, the injection valve 43A stops the introduction of the pilot pressure and opens when the injection start condition is met, and introduces the pilot pressure and closes when the injection completion condition is met.

[0284] In addition, the regulating valve between the regulating accumulator 41 and the head side chamber 31h (not shown here) can also be composed of regulating valves 45A and 45B, which are composed of two check valves connected in parallel. The regulating valve 45A allows the flow from the regulating accumulator 41 to the head side chamber 31h (below the figure), and prohibits the flow to the opposite side. On the contrary, the regulating valve 45B prohibits the flow from the regulating accumulator 41 to the head side chamber 31h (below the figure), and allows the flow to the opposite side. In addition, no matter which check valve is used, the flow of both sides is prohibited when the pilot pressure is introduced.

[0285] The regulating valves 45A and 45B stop introducing the pilot pressure and open when the injection start condition is satisfied. When the working fluid is replenished from the regulating accumulator 41 to the head side chamber 31h, the regulating valve 45A allows the flow of the working fluid. When the regulating accumulator 41 absorbs the pressure of the head side chamber 31h, the regulating valve 45B allows the flow of the working fluid.

[0286] In addition, regulating valves 45A and 45B may be provided in place of the regulating valve 45 in the first embodiment.

[0287] In addition, if Fig.12 As shown in FIG. 1 , the accumulator for applying hydraulic pressure to the head side chamber 31h may be switched by a single valve instead of the injection valve and the regulating valve which are controlled independently of each other. Fig.12 , a 3-port 2-position (3-way 2-position) switching valve 46 is illustrated for switching the connection destination of the head side chamber 31h (the flow path at the bottom of the figure) between the injection accumulator 39 and the regulating accumulator 41. The switching valve 46 also has the function of a servo valve and a flow control valve (flow regulating valve with pressure compensation), for example.

[0288] (4.2. Modification of the operation of the injection device)

[0289] Fig.13is a schematic diagram showing a modified example of the operation of the injection device 9 of the first embodiment, and Figure 5 (a) Corresponding.

[0290] As described in the description of the first embodiment, before the injection is completed (before the adjustment valve 45 is opened), the position of the boosting piston 35 may not be at the retreat limit ( Fig.13 Indicated by double-dotted lines). Fig.13 This method is exemplified.

[0291] In addition, in this embodiment, after the injection is completed, the action of advancing the booster piston 35 is not required. Therefore, the injection valve 43 does not need to be closed before the injection piston 33 stops. That is, the injection valve 43 can be closed after the injection piston 33 stops. In addition, for the same reason, if the viewpoint of quickly obtaining the set pressure Pc1 is ignored, the timing of opening the regulating valve 45 can be delayed a lot relative to the timing of stopping the plunger 23 and / or the timing of closing the injection valve 43.

[0292] In the above-mentioned embodiment and modification, the die casting machine 1 is an example of a molding machine, the molten liquid is an example of a molding material, and the metal mold 101 is an example of a die.

[0293] The present invention is not limited to the above-described embodiments and modifications, and can be implemented in various forms.

[0294] In the description of the present embodiment, the reduction of burrs is exemplified as an effect of decompression. However, it is not necessary to implement the technology of the present invention in such a way that burrs are reduced.

[0295] The molding machine is not limited to a die casting machine. For example, the molding machine may be other metal molding machines, an injection molding machine for molding resins, or a molding machine for molding materials such as wood powder mixed with thermoplastic resins. In addition, the molding machine is not limited to horizontal mold closing and horizontal injection, and may be, for example, vertical mold closing and vertical injection, vertical mold closing and horizontal injection, or horizontal mold closing and vertical injection. The die casting machine is not limited to a cold chamber die casting machine, and may be, for example, a hot chamber die casting machine.

[0296] As described in the description of the embodiment, the driving part of the injection device is not limited to the hydraulic type, and may be an electric type, or a hybrid type that is a combination of the electric type and the hydraulic type. In the case of the electric type, for example, the pressure reduction can be achieved by controlling the driving force of a rotary motor or a linear motor. In the case of the hybrid type, the pressure reduction can be achieved by controlling the driving force of the motor, or by controlling the hydraulic pressure as in the embodiment, or by combining the two.

[0297] In the case of using an injection cylinder, the structure for reducing the pressure in the head side chamber to achieve decompression is not limited to the first and second embodiments. For example, the pressure in the head side chamber may be reduced by opening a valve connecting the head side chamber and the tank. In addition, the structure for increasing the pressure in the rod side chamber to achieve pressurization is not limited to the third embodiment. For example, the working fluid may be supplied to the rod side chamber by a cylinder driven by a pump or an electric motor.

[0298] The regulating accumulator for decompression may not be used for pressurization. For example, the injection device may be configured to perform only decompression of the pressure increase and the pressure decrease, or may have an accumulator for decompression and an accumulator for pressurization separately.

[0299] Injection is not limited to low-speed injection and high-speed injection, and for example, laminar filling can also be performed at a low speed. The pressurizing member for local pressurization can also be used as an ejection pin for ejecting the molded product formed by solidifying the molding material from the mold. The working fluid is not limited to oil, and for example, it can also be water.

[0300] Explanation of symbols

[0301] 1: die casting machine (molding machine), 9: injection device, 21: sleeve, 23: plunger, 25: driving part, 27: injection cylinder, 101: metal mold (die), 107: space (inside of the die).

Claims

1. An injection device that performs injection by pushing a molding material in a sleeve into a mold by a plunger, and pressure holding by applying a predetermined set pressure to the molding material filled in the mold for a certain period of time by the plunger, in, A driving unit is provided, the driving unit being connected to the plunger and applying a driving force to the plunger for reducing the pressure applied by the plunger to the molding material filled in the mold to the set pressure.

2. The injection device according to claim 1, in, The driving unit has: an injection cylinder connected to the plunger; a hydraulic device that applies hydraulic pressure to the injection cylinder, The injection cylinder has: A piston rod connected to the rear portion of the plunger; an injection piston fixed to the rear of the piston rod; The injection cylinder contains the injection piston and allows the injection piston to slide. The injection cylinder is divided into a rod side chamber at the front and a head side chamber at the rear by the injection piston. The hydraulic device includes a pressure regulating unit that reduces the pressure of the head side chamber when the pressure reduction is performed.

3. The injection device according to claim 2, in, The pressure regulating unit includes a regulating accumulator for absorbing the hydraulic pressure of the injection cylinder when the pressure is reduced.

4. The injection device according to claim 3, in, The injection cylinder has: A small-diameter cylinder portion communicated with the head-side chamber; a large-diameter cylinder portion connected in series with the small-diameter cylinder portion and having a diameter larger than that of the small-diameter cylinder portion; A small-diameter piston slidably received in the small-diameter cylinder; A large-diameter piston is fixed in series to the small-diameter piston and is slidably received in the large-diameter cylinder portion, and divides the interior of the large-diameter cylinder portion into a front chamber on the side of the small-diameter cylinder portion and a rear chamber on the opposite side thereof. The adjustment accumulator is in communication with the rear chamber.

5. The injection device according to claim 4, in, The hydraulic device includes an injection accumulator for supplying working fluid to the head side chamber when performing the injection. The pressure of the adjustment accumulator is lower than a first pressure obtained by multiplying the pressure of the injection accumulator by the square of a ratio obtained by dividing the diameter of the small-diameter piston by the diameter of the large-diameter piston.

6. The injection device according to claim 3, in, The adjustment accumulator is in communication with the head side chamber.

7. The injection device according to claim 6, in, The hydraulic device includes an injection accumulator for supplying working fluid to the head side chamber when performing the injection. The pressure of the trim accumulator is lower than the pressure of the injection accumulator.

8. The injection device according to claim 1, in, The driving unit has: an injection cylinder connected to the plunger; a hydraulic device that applies hydraulic pressure to the injection cylinder, The injection cylinder has: A piston rod connected to the rear portion of the plunger; an injection piston fixed to the rear of the piston rod; The injection cylinder contains the injection piston and allows the injection piston to slide. The injection cylinder is divided into a rod side chamber at the front and a head side chamber at the rear by the injection piston. The hydraulic device includes a pressure regulating unit that increases the pressure of the rod side chamber when the pressure is reduced.

9. The injection device according to claim 8, in, The pressure regulating unit includes a regulating accumulator for applying a hydraulic pressure to the rod side chamber when performing the pressure reduction.

10. The injection device according to claim 1, in, The driving unit may selectively perform the decompression and the pressurization for increasing the pressure applied by the plunger to the molding material filled in the mold to reach the set pressure.

11. The injection device according to claim 5, in, An ACC pressure regulating unit is provided, the ACC pressure regulating unit regulating the pressure of the regulating accumulator within a range from a pressure lower than the first pressure to a pressure higher than the first pressure.

12. The injection device according to claim 1, in, A control device is provided to control the driving unit to perform the decompression.

13. The injection device according to claim 1, in, have: an input device that receives an operation for setting the set pressure; a control device that controls the driving unit based on the set pressure set by operating the input device, The driving unit has: an injection cylinder connected to the plunger; a hydraulic device that applies hydraulic pressure to the injection cylinder, The hydraulic device includes an injection accumulator for supplying working fluid to the injection cylinder during the injection. The control device allows setting, as the set pressure, a pressure lower than a pressure obtained by converting the pressure of the injection accumulator into a pressure applied to the molding material by the plunger.

14. The injection device according to claim 4, in, When the injection is performed, the large-diameter piston is located in front of the retraction limit.

15. A forming machine comprising: The injection device according to claim 1; A mold clamping device is provided to hold the mold.

16. A method for manufacturing a molded product, comprising: Injection step, the forming material in the sleeve is pushed into the mold by the plunger. a pressure holding step of applying a predetermined set pressure to the molding material filled in the mold by the plunger for a certain period of time, The decompression step is to reduce the pressure applied by the plunger to the molding material filled into the mold in the injection step and reach the set pressure.

17. The method for producing a molded product according to claim 16, in, The forming material is a metal material.

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