Local pressurizing device, molding machine, and molding method

Abstract

To provide a local pressurization device which can suitably use a pressurization member.SOLUTION: A local pressurization device 2 has a pressurization member 41 whose a front end is exposed to a space 107 of a mold 101, and a driving part 45 for imparting forward force to the pressurization member 41. The pressurization member 41 is positioned at an initial position forward from a retreat limit when molten metal reaches the position of the pressurization member 41, and is retreated from the initial position by being pushed by the molten metal.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a local pressurizing device for locally pressurizing a molding material inside a mold, a molding machine including the local pressurizing device, and a molding method for performing local pressurization. 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 molding methods such as the die-casting method, a technique for performing so-called local pressurization is known (for example, Patent Documents 1 to 4 below). In this technique, after a molding material is filled inside a mold (a space formed by the mold; the same applies hereinafter), the molding material is pressed by a pressurizing pin inserted into the mold. Thereby, for example, sink marks caused by solidification shrinkage of the molding material are reduced.

[0003] When filling the molding material inside the mold, the pressurizing pin waits at the retraction limit of its stroke (the driving limit on the side opposite to the inside of the mold). Thereby, when the pressurizing pin is advanced to pressurize the molding material after filling, the maximum value that the forward distance can take can be set as the stroke of the pressurizing pin. That is, the stroke of the pressurizing pin can be utilized to the maximum extent.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0005] The usage mode of the pressure pin affects the quality of the molding material. For example, if the timing of the start of the forward movement of the pressure pin is too early, the plastic flow of the molding material will not occur, and a sufficient pressing effect cannot be obtained. Also, if the timing of the start of the forward movement is late, the pressure pin cannot be pushed to a sufficient depth due to the solidification of the molding material, and again, a sufficient pressing effect cannot be obtained. Therefore, there is a need for a local pressing device, a molding machine, and a molding method that can preferably use the pressing member (pressure pin).

Means for Solving the Problem

[0006] A local pressing device according to one aspect of the present disclosure includes a pressing member having a front end exposed inside a mold, and a drive unit that applies a forward force to the pressing member. The pressing member is positioned at an initial position in front of the retraction limit when the molding material reaches the position of the pressing member, and is pushed by the molding material and retracts from the initial position.

[0007] A molding machine according to one aspect of the present disclosure includes the above-described local pressing device, a mold clamping device that opens and closes and clamps the mold, and an injection device that injects the molding material into the mold.

[0008] A molding method according to one aspect of the present disclosure includes an injection step of injecting a molding material into a mold, and a local pressing step of advancing a pressing member having a front end exposed inside the mold to press the molding material inside the mold. The pressing member is positioned at an initial position in front of the retraction limit when the molding material reaches the position of the pressing member, and is pushed by the molding material and retracts from the initial position.

Advantages of the Invention

[0009] According to the above configuration or procedure, the pressing member can be preferably used by utilizing the retraction of the pressing member. For example, the surge pressure generated when the molding material is filled inside the mold can be absorbed by the retraction of the pressing member. Also, for example, the arrival of the molding material at the pressing member can be detected based on the retraction of the pressing member, and the timing of the start of the forward movement of the pressing member can be preferably determined.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

MODE FOR CARRYING OUT THE INVENTION

[0011] Hereinafter, with reference to the drawings, a plurality of embodiments according to the present disclosure will be described. For the embodiments described relatively later among the plurality of embodiments, basically, only the differences from the embodiments described earlier will be described. For matters not particularly mentioned, they may be the same as those in the embodiments described earlier or may be inferred from the embodiments described earlier. Also, for components corresponding to each other in the plurality of embodiments, even if there are differences, for convenience, they may be given the same reference numerals.

[0012] First, the main points of the local pressurizing device according to the embodiments of the present disclosure will be described below. Thereafter, more specific first to fifth embodiments and the like will be described.

[0013] <Main points of the local pressurizing device according to the embodiment> Figs. 1(a) to 3(b) are schematic diagrams showing an overview of the operations of the local pressurizing device 2 (hereinafter, sometimes simply referred to as "pressurizing device 2") and the injection device 9 according to the embodiment. Note that the distinction between the components of the pressurizing device 2 and the components of the injection device 9 does not necessarily have to be clear. Also, the combination of both may be regarded as an injection device.

[0014] Figs. 1(a), 2(a) and 3(a) schematically show the pressurizing device 2 and the injection device 9, and also show the states at different times during the molding cycle (more specifically, during the injection cycle). Fig. 1(b) is an enlarged view of the region Ib in Fig. 1(a). Fig. 2(b) is an enlarged view of the region IIb in Fig. 2(a). Fig. 3(b) is an enlarged view of the region IIIb in Fig. 3(a).

[0015] Figs. 1(a) and 1(b) show a state in which an injection process of injecting a molding material (for example, a molten metal 109 in a molten state) into the mold 101 is being performed. In the injection process, as indicated by the arrow a1, the plunger 21 (injection plunger) advances toward the mold 101, thereby extruding the molten metal 109 in the sleeve 19 into the inside (space 107) of the mold 101.

[0016] Conventionally, the pressing member 41 (pressing pin) of the pressing device 2 waited at the retraction limit (the driving limit on the side opposite to the space 107) before the forward movement of the plunger 21 started (before the injection started). On the other hand, in the present embodiment, it is waiting at a position in front of the retraction limit (on the side of the space 107) (for example, the forward limit).

[0017] Figures 2(a) and 2(b) show the state after Figures 1(a) and 1(b). As the injection process proceeds, the molten metal 109 fills substantially the entire space 107. Figures 2(a) and 2(b) show such a state. In the description of the embodiment, reaching such a state may be referred to as the completion of filling. When the filling is completed, the pressure of the molten metal 109 increases as the plunger 21 pushes the molten metal 109 that has lost its escape space. At this time, a so-called surge pressure may occur, which is accompanied by a temporary and rapid increase in pressure.

[0018] In the process from the start of injection to the completion of filling, the molten metal 109 reaches the position of the pressing member 41. Then, as shown by the arrow a2 (Figure 2(a)) and the arrow a3 (Figure 2(b)), the pressing member 41 is pushed by the molten metal 109 and retracts. The retraction of the pressing member 41 may occur immediately after the molten metal 109 arrives, or may retract when the molten metal 109 is substantially filled in the space 107 and the pressure increases as described above. Also, the pressing member 41 may reach the retraction limit (example shown in the figure) or may not reach it.

[0019] Figures 3(a) and 3(b) show the state after Figures 2(a) and 2(b). When the filling is completed, as shown by the arrow a4 (Figure 3(a)) and the arrow a5 (Figure 3(b)), the pressing member 41 advances. As a result, the molten metal 109 is locally pressed. By this pressing, for example, the probability of the occurrence of sink marks (cavities due to the solidification shrinkage of the molten metal) is reduced. Note that after the filling is completed, the plunger 21 may, for example, advance and contribute to the pressure increase of the molten metal 109, or may simply stay at the position at the time of filling completion.

[0020] As described above, in the pressing device 2 according to the embodiment, when the molten metal 109 reaches the position of the pressing member 41, the pressing member 41 is located at an initial position (for example, the forward limit) in front of the retreat limit. Then, it is pushed by the molten metal 109 and retreats from the initial position. Thereby, various effects can be obtained.

[0021] For example, the surge pressure is absorbed by the retreat of the pressing member 41. By absorbing the surge pressure, the probability of generating burrs (the portions formed when the molten metal 109 protrudes outside the space 107) is reduced. That is, the pressing member 41 can be effectively used not only as a member for local pressing but also as a member for absorbing the surge pressure.

[0022] Also, for example, by detecting the retreat of the pressing member 41, the arrival and / or filling completion of the molten metal can be detected. Therefore, based on the detection of the retreat of the pressing member 41, the timing of starting the forward movement of the pressing member 41 can be appropriately determined. More specifically, for example, it is as follows.

[0023] As a comparative example to the above embodiment, there is an aspect of determining the timing of starting the forward movement of the pressing member 41 based on an increase in the driving force of a driving unit (for example, a hydraulic cylinder) that drives the plunger 21 (in other words, an increase in the pressure received by the plunger 21 from the molten metal 109). However, since the solidification of the molten metal 109 progresses during injection, etc., the increase in the pressure of the molten metal 109 at the position of the plunger 21 does not necessarily coincide with the arrival and / or pressure increase of the molten metal 109 at the position of the pressing member 41. As a result, the timing of starting the forward movement of the pressing member 41 is not necessarily appropriate for the state of the molten metal 109 at the position of the pressing member 41. On the other hand, in the present embodiment, since the arrival and / or pressure increase of the molten metal 109 can be detected at the position of the pressing member 41, such inconvenience does not occur.

[0024] As another comparative example, there is an aspect in which a sensor (for example, a pressure sensor, a temperature sensor, or an energization sensor) for detecting the arrival of the molten metal 109 is provided at an appropriate position of the mold 101. However, depending on the attachment position of the sensor, the same disadvantages as in the above comparative example occur. Further, such a sensor is provided at a position exposed to the space 107 so as to be in contact with the molten metal 109 or in the vicinity thereof. Therefore, durability against the pressure and heat of the molten metal 109 is required. However, the sensor 43 (FIG. 1(b)) for detecting the retreat of the pressing member 41 does not have to be exposed to the space 107 and can also be arranged at a position farther behind the pressing member 41 as will be described later. Therefore, the durability required for the sensor 43 can be reduced. Further, in the aspect in which the sensor 43 is a position sensor, unlike the sensor according to the comparative example, it can be used for feedback control when the pressing member 41 is advanced.

[0025] <First Embodiment> (Overall Configuration of Die Casting Machine) FIG. 4 is a side view (including a partial cross-sectional view) showing the configuration of the main part of the die casting machine DC according to the first embodiment. In the description made with reference to FIG. 4, for the sake of convenience, the left side of FIG. 4 may be referred to as the front, and the right side of FIG. 4 may be referred to as the rear.

[0026] The die casting machine DC has a mold (mold 101) and a die casting machine 1 holding the mold 101. The die casting machine 1 is configured as an apparatus for manufacturing a product (molded product, die-cast product) made of a solidified molding material by injecting (filling) a molten molding material into the inside (space 107) of the mold 101.

[0027] The molding material is, for example, a metal such as aluminum. The molten metal may be called molten metal as described above. Note that instead of the molten molding material, a molding material in a solid-liquid coexisting state (semi-solidified state or semi-molten state) may be injected into the space 107.

[0028] The mold 101 has, for example, a fixed mold 103 and a movable mold 105 facing the fixed mold 103. The main part of the space 107 is formed between the fixed mold 103 and the movable mold 105. The fixed mold 103 is a non-moving mold. The movable mold 105 is a mold that moves in the direction facing the fixed mold 103 (the mold opening and closing direction). The mold opening and closing direction is, for example, the horizontal direction. In FIG. 4 and the like, for the sake of convenience, the cross-section of the fixed mold 103 or the movable mold 105 is shown with one type of hatching. However, these molds may be of the direct carving type or the nested type. Further, the fixed mold 103 and / or the movable mold 105 may include a die base.

[0029] The die-casting machine 1 has a machine body 3 that performs mechanical operations and a control device 5 that controls the machine body 3. The machine body 3 has, for example, a mold clamping device 7 that opens and closes and clamps the mold 101, an injection device 9 that injects molten metal into the space 107, and an extrusion device (not shown) that extrudes the product formed by solidification of the molten metal from the fixed mold 103 or the movable mold 105.

[0030] As a specific example of the pressure device 2 described above, the pressure device 2A (see FIG. 5 described later) is included in the die-casting machine DC with a mold. At least a part of the pressure device 2A (for example, the pressure member 41 and its drive part) may be regarded as a component attached to the mold 101, or may be regarded as a component of the die-casting machine 1. When paying attention to each part of the die-casting machine DC with a mold (for example, the pressure device 2A), the control device 5 may be regarded as a component of each such part.

[0031] In the die-casting machine DC with a mold, the configuration and operation of components other than the pressure device 2A may be known or novel. In other words, they may be in various forms. Regarding configurations and operations that may be known configurations and operations, the description will be omitted as appropriate.

[0032] In the following description of the die-casting machine 1, the description will generally be carried out in the following order. · Mold clamping device 7 · Injection device 9 ·Control device 5 ·Other configurations of the die-casting machine ·Pressurizing device 2A ·Operations related to injection and local pressurization ·Summary of the first embodiment

[0033] (Mold clamping device) The mold clamping device 7 has, for example, a base 11, a fixed die plate 13 fixed on the base 11, a movable die plate 15 movable in the mold opening / closing direction on the base 11, and a plurality (for example, four) of tie bars 17 inserted through these die plates. The fixed die plate 13 and the movable die plate 15 face each other in the mold opening / closing direction. The fixed die plate 13 holds the fixed mold 103 on the surface facing the movable die plate 15. The movable die plate 15 holds the movable mold 105 on the surface facing the fixed die plate 13. The opening and closing of the mold 101 are performed by the movement of the movable die plate 15 in the mold opening / closing direction. Further, when the tie bars 17 are extended in the mold-closed state, a mold clamping force corresponding to the extension amount is applied to the mold 101.

[0034] (Injection device) The injection device 9 is located behind the fixed die plate 13 (on the side opposite to the movable die plate 15). The injection device 9 has a sleeve 19 communicating with the space 107, a plunger 21 for extruding the molten metal in the sleeve 19 into the space 107, and a drive unit 23 for driving the plunger 21. Since the sleeve 19 and the plunger 21 can be regarded as consumables, it is also possible to regard only the drive unit 23 as the injection device.

[0035] The sleeve 19 is provided so as to be inserted through the fixed die plate 13. Note that the sleeve 19 may not be inserted through the fixed mold 103 (example in FIG. 4), or may be inserted through it (example in FIG. 1(a)). The sleeve 19 is generally a cylindrical member and is arranged to extend in the horizontal direction (front-rear direction). A supply port 19a for supplying molten metal is opened on the upper surface of the sleeve 19.

[0036] The plunger 21 has a plunger tip 21a that slides within the sleeve 19 and a plunger rod 21b fixed to the plunger tip 21a. The plunger rod 21b extends in the front-rear direction, and its rear end is connected to the drive unit 23 by a coupling 25.

[0037] In FIG. 4, the state before the start of injection is shown. At this time, the plunger tip 21a is (at least partially) positioned within the sleeve 19 behind the supply port 19a. In this state, molten metal is poured into the supply port 19a by a hot water supply device (not shown) or the like. Next, the plunger tip 21a slides (advances) toward the space 107 by the driving force of the drive unit 23. As a result, the molten metal is injected into the space 107.

[0038] The drive unit 23 may be, for example, a hydraulic type (oil hydraulic type), an electric type, or a hybrid type (a combination of a hydraulic type and an electric type). In FIG. 1(a), a hydraulic drive unit 23 is illustrated. That is, the drive unit 23 has a hydraulic cylinder (injection cylinder 27) connected to the plunger 21 and a hydraulic device (not shown) that supplies hydraulic fluid to the injection cylinder 27 and the like.

[0039] The configuration of the injection cylinder 27 is arbitrary. For example, the injection cylinder 27 may be a single-cylinder type (example in FIG. 1(a)) or a pressure-boosting type (refer to FIG. 12 described later). The single-cylinder injection cylinder 27 (FIG. 1(a)) has a cylinder member 31, a piston 33 slidable inside the cylinder member 31, and a piston rod 37 extending forward (toward the plunger 21 side) from the piston 33.

[0040] The cylinder member 31 is stationary. The inside of the cylinder member 31 is partitioned by the piston 33 into a rod-side chamber 31r on the piston rod 37 side and a head-side chamber 31h on the opposite side. The piston rod 37 extends outside the cylinder member 31, and its front end is connected to the rear end of the plunger 21 by a coupling 25.

[0041] When the hydraulic fluid is supplied to the head side chamber 31h, the piston 33 advances. As a result, the plunger 21 connected to the piston 33 via the piston rod 37 and the coupling 25 advances. Consequently, the molten metal in the sleeve 19 is injected into the space 107.

[0042] (Control device) The control device 5 may be configured to include a computer, for example, although not particularly shown in the drawings. The computer may be configured to include, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and an external storage device, although not particularly shown in the drawings. By the CPU executing the programs stored in the ROM and / or the external storage device, various functional units that perform various operations (including control) are constructed. Further, the control device 5 may include a logic circuit that executes a certain operation, may include a power supply circuit, or may be conceptually included a driver. The control device 5 may be hardware-wise integrated in one place or may be distributed in a plurality of places.

[0043] (Other configurations of the die casting machine) The die casting machine DC with a mold may have various sensors. And the control device 5 may control each part based on the detection values of various sensors.

[0044] Examples of the above sensors will be given. For example, although not particularly shown in the drawings, a position sensor that detects the position of the plunger 21 and / or a sensor that detects the driving force of the driving unit 23 may be provided. Since the speed can be obtained by differentiating the position, the position sensor may be regarded as a speed sensor. As a sensor that detects the driving force of the driving unit 23, for example, in an embodiment where the driving unit 23 has an injection cylinder 27, a pressure sensor that detects the pressure in the head side chamber 31h (and, if necessary, a pressure sensor that detects the pressure in the rod side chamber 31r) may be used.

[0045] A sensor for detecting the position of the plunger 21 is used, for example, to control the injection speed (in other words, the speed of the plunger 21). A sensor for detecting the driving force of the drive unit 23 is used to control the injection pressure (in other words, the pressure applied by the plunger 21 to the molding material). However, as will be described later, in the present embodiment, the casting pressure may be realized by pressure control by the pressurizing device 2, and the control of the injection pressure is not essential.

[0046] (Pressurizing device) FIG. 5 is a schematic diagram showing the configuration of the pressurizing device 2A.

[0047] As described with reference to FIG. 1(a), the pressurizing device 2A includes a pressurizing member 41 for pressurizing the molten metal and a sensor 43 for detecting the retraction of the pressurizing member 41. The pressurizing device 2A also has a drive unit 45A which is a specific example of the drive unit 45 (FIG. 1(a)) for driving the pressurizing member 41.

[0048] The drive unit 45A may have an appropriate configuration such as a hydraulic type or an electric type. In the first embodiment, a hydraulic type drive unit 45A is taken as an example. The hydraulic type drive unit 45A includes a hydraulic cylinder (pressurizing cylinder 47) and a hydraulic device 49 for supplying the working fluid to the pressurizing cylinder 47 and the like.

[0049] In the following description of the pressurizing device 2A, the description will generally be made in the following order. · Pressurizing member 41 · Pressurizing cylinder 47 · Sensor 43 · Hydraulic device 49

[0050] (Pressurizing member) The shape of the pressurizing member 41 may generally be pin-shaped with the longitudinal direction being the advancing and retracting direction (example shown in the figure), or may not be pin-shaped. As an example of the latter, a block-shaped shape having a diameter larger than the length of the pressurizing member 41 in the advancing and retracting direction can be cited. Also, the shape of the cross section perpendicular to the advancing and retracting direction of the pressurizing member 41 may be circular (example shown in the figure), or may be a shape other than circular. The dimensions of the pressurizing member 41 are also arbitrary.

[0051] As shown in FIG. 1(b), at least a part of the tip side (space 107 side) of the pressing member 41 may be tapered so that the diameter becomes smaller toward the tip side. In this case, it becomes easier to pull out the pressing member 41 from the solidified molding material. The range to be tapered may be set as appropriate. In the illustrated example, when the pressing member 41 is located at the forward limit, the entire portion of the pressing member 41 located within the space 107 is tapered. Of course, the pressing member 41 may have a non-tapering shape (for example, a shape with a constant diameter).

[0052] The dimensions of the pressing member 41 are arbitrary. For example, when the diameter of the front end of the pressing member 41 (for example, the equivalent diameter of a circle based on the area for applying pressure in the forward direction to the molten metal. The same applies to the plunger 21.) is d and the diameter of the front end of the plunger 21 is D, d / D may be 0.2 or more and 0.5 or less. Of course, it may be outside this range.

[0053] The pressing member 41 may be disposed in the fixed mold 103 (example shown in the figure) or in the movable mold 105. In the description of the present embodiment, for convenience, the description may be made on the premise that the pressing member 41 is disposed in the fixed mold 103.

[0054] The pressing member 41 may, for example, slide (or may contact) in the advancing and retreating direction with respect to a part or all of the mold (fixed mold 103 or movable mold 105). A part of the rear end side of the pressing member 41 (the part connected to the drive unit 45A) may be located outside the mold, or the whole of it may be located inside the mold. As an example of the latter, an aspect in which the rear end side portion of the pressing member 41 is located in a space formed by a die base (not shown) can be cited.

[0055] The advancing and retracting direction of the pressing member 41 may be an appropriate direction. For example, the advancing and retracting direction may be the mold opening and closing direction (the left - right direction in FIG. 4), or may be a direction intersecting (orthogonal or inclined) with the mold opening and closing direction. However, if the advancing and retracting direction is the mold opening and closing direction, for example, the operation of peeling the molded product from the mold in which the pressing member 41 is disposed (which may be a mold opening operation and / or an extrusion operation) enables the pressing member 41 to be pulled out from the molded product.

[0056] The arrangement position of the pressing member 41 with respect to the space 107 may be set as appropriate. For example, as shown in FIGS. 1(a) and 1(b), the space 107 has a product part 107a having a shape corresponding to the product shape, a runner 107e for guiding the molten metal from the sleeve 19 to the product part 107a, and an overflow 107b into which the excess molten metal flows. The pressing member 41 may press the molten metal located in any of these spaces.

[0057] In the example of FIG. 1(a), the pressing member 41 is arranged to press the molten metal flowing into the overflow 107b. The overflow 107b is usually connected to the outer periphery of the product part 107a (particularly the position away from the sleeve 19) when viewed in the mold opening and closing direction. Therefore, the pressing member 41 that presses the molten metal in the overflow 107b can apply pressure to the molten metal on the outer peripheral side of the molten metal in the product part 107a, to which it is difficult to apply pressure by the plunger 21. As a result, for example, the molten metal in the product part 107a is likely to be uniformly pressurized throughout. Thus, when molding a large - sized product, the necessity of increasing the pressure applied to the molten metal by the plunger 21 can be reduced. From another perspective, the necessity of increasing the size of the die - casting machine 1 can be reduced.

[0058] Note that, as shown in Fig. 1(b), the fixed mold 103 (the mold where the pressing member 41 is disposed) may have a recess 107c on the surface on the movable mold 105 side, into which the tip side portion of the pressing member 41 is inserted and removed. This recess 107c may have a diameter larger than that of the tip side portion of the pressing member 41, for example, and may have an inverted taper shape where the diameter increases toward the movable mold 105 side, for example. The recess 107c secures a volume in the space 107 for inserting and removing the pressing member 41 into and from the space 107. Further, due to the inverted taper shape, the solidified molding material easily comes off from the fixed mold 103. Of course, the fixed mold 103 may not have such a recess 107c, or a recess 107c that is not an inverted taper shape may be formed.

[0059] The forward limit and the backward limit of the pressing member 41 may be defined by a member or a part (stopper) with which the pressing member 41 abuts when the pressing member 41 moves forward or backward being provided on the mold 101 or the like, or may be defined by the driving limit of the driving unit 45 that drives the pressing member 41. Examples of the latter driving limit include, for example, the forward limit and the backward limit of the piston 55 (described later) with respect to the cylinder member 53 (described later) in the pressing cylinder 47. Note that, in the description of the embodiment, the illustration of the member that defines the forward limit and the backward limit is appropriately omitted.

[0060] The number of the pressing members 41 may be set as appropriate, and may be one or two or more. However, in the description of the embodiment, only one pressing member 41 is basically illustrated in order to avoid complication of the drawing.

[0061] (Pressing cylinder) As shown in Fig. 5, the pressing cylinder 47 has, for example, a cylinder member 53, a piston 55 slidable inside the cylinder member 53, and a piston rod 57 extending from the piston 55 to the outside of the cylinder member 53.

[0062] The cylinder member 53 is, for example, generally a cylindrical member. The shape of the cross section inside the cylinder member 53 is, for example, circular. The outer shape (the shape on the outer side) of the cylinder member 53 may be an appropriate shape such as a rectangular parallelepiped shape. The piston 55 is, for example, generally a cylindrical member and is slidable in the axial direction inside the cylinder member 53. The space inside the cylinder member 53 is partitioned by the piston 55 into a rod side chamber 53r on the piston rod 57 side and a head side chamber 53h on the opposite side. The piston rod 57 is, for example, generally a cylindrical member. The diameter of the piston rod 57 is smaller than the diameter of the piston 55. The difference may be set as appropriate.

[0063] The pressure cylinder 47 is arranged coaxially with the pressure member 41, for example, on the side opposite to the space 107 of the pressure member 41 (the right side in FIG. 5), and the piston rod 57 side is directed toward the pressure member 41. The cylinder member 53 is made immovable with respect to the fixed mold 103 (the mold in which the pressure member 41 is arranged). For example, the cylinder member 53 is fixed to the fixed mold 103 and / or the fixed die plate 13 by bolts or the like. The tip of the piston rod 57 is connected to the rear end of the pressure member 41 by an appropriate coupling (reference numeral omitted). Therefore, for example, in the pressure cylinder 47, when the working fluid is supplied to the head side chamber 53h, the piston 55 moves toward the rod side chamber 53r. As a result, the pressure member 41 connected to the piston 55 via the piston rod 57 advances toward the space 107.

[0064] Conversely to the above description, the cylinder member 53 may be fixed to the pressing member 41, and the piston rod 57 may be made immovable with respect to the fixed mold 103. Also, the direction of the pressing cylinder 47 may be opposite to the above description. That is, regarding the combination of which of the cylinder member 53 and the piston rod 57 is made immovable and in which direction the piston rod 57 extends, there are three possibilities other than those shown in the drawings. In connection with the above, the cylinder chamber to which the working fluid is supplied when the pressing member 41 is advanced toward the space 107 may be the rod-side chamber 53r. In the description of the present embodiment, for convenience, the description may be made on the premise of the illustrated mode (the mode in which the piston rod 57 is directed toward the pressing member 41 and the cylinder member 53 is immovable).

[0065] The number of pressing members 41 driven by one pressing cylinder 47 may be one (the example shown in the drawings) or two or more. In the latter case, for example, as can be inferred from a known extrusion device, a plate-like member orthogonal to the piston rod 57 may be fixed to the tip of the piston rod 57, and a plurality of pressing members 41 may be fixed to this plate-like member in parallel. In the description of the present embodiment, basically, the illustrated mode (the mode in which one pressing cylinder 47 drives one pressing member 41) is taken as an example.

[0066] As can be understood from the description to be described later, in the present embodiment, the movement of the piston 55 by the supply of the working fluid to the rod-side chamber 53r (the retraction of the pressing member 41 from the space 107 by the driving unit) does not necessarily have to be performed. Therefore, the rod-side chamber 53r may or may not be filled with the working fluid. In the latter case, for example, the rod-side chamber 53r may be open to the atmosphere. In this case, a small amount of oil as the working fluid may be arranged in the rod-side chamber 53r for purposes such as lubrication. Also, when the rod-side chamber 53r is filled with the working fluid, the rod-side chamber 53r may be such that only the shortage of the working fluid is supplied from the tank or the drive source (for example, the pump) when its volume expands.

[0067] Furthermore, the pressurizing cylinder 47 may be configured such that the piston 55 extends from the cylinder member 53 to the side opposite to the head side chamber 53h (in another aspect, the diameter of the piston 55 is the same as the diameter of the piston rod 57) and does not have a rod side chamber 53r. However, in the description of the present embodiment, for convenience, the description may be made on the premise of the illustrated aspect (the aspect in which the pressurizing cylinder 47 has a rod side chamber 53r).

[0068] (Sensor for detecting the retreat of the pressurizing member) As described above, the sensor 43 detects the retreat of the pressurizing member 41. The specific configuration of the sensor 43 may be in various aspects. Some examples are given below.

[0069] The sensor 43 may be, for example, a limit switch that is turned ON (or OFF) when the pressurizing member 41 retreats from an initial position (e.g., the forward limit) to a predetermined position. The limit switch may be a contact type or a non-contact type.

[0070] Also, the sensor 43 may be, for example, a position sensor that detects the position of the pressurizing member 41 (in another aspect, the amount of retreat). Examples of the position sensor include a linear encoder.

[0071] Depending on the operation mode of the pressurizing cylinder 47, when the pressurizing member 41 retreats, the pressure in the head side chamber 53h increases. Therefore, a pressure sensor 71H (see FIG. 6 described later) that detects the pressure in the head side chamber 53h may be used as the sensor 43.

[0072] As understood from the above specific examples, the detection of the retreat may be a detection of the presence or absence of the retreat (e.g., by a limit switch) or a detection of the amount of retreat (e.g., by a position sensor). Also, the above specific examples may be used in combination. The configuration of the sensor 43 and the amount of retreat when the sensor 43 detects the retreat may be the same or different from each other among the plurality of pressurizing members 41 (or the plurality of drive units 45).

[0073] The position of the sensor 43 may be set at any position as long as the retraction of the pressing member 41 can be detected. For example, the above-described limit switch or position sensor may directly detect the retraction of the pressing member 41 (see Fig. 1(b)), or may detect the retraction (movement) of another member connected to the pressing member 41 (Fig. 5). In the example of Fig. 5, a detected portion 44 is provided which is fixed to the piston 55 and extends rearward (opposite to the pressing member 41) from the cylinder member 53. Then, the sensor 43 detects the retraction of the detected portion 44. As understood from the description of the pressing cylinder 47, the detected portion 44 may be located inside the mold 101 or outside the mold 101.

[0074] (Hydraulic device related to the pressing device) The hydraulic device 49 shown in Fig. 5 has, for example, a low-pressure circuit 59L and a high-pressure circuit 59H as a hydraulic circuit for supplying a working fluid to the pressing cylinder 47 and the like. Hereinafter, both may be referred to as the hydraulic circuit 59 without distinction (the reference numeral is shown in Fig. 6). The low-pressure circuit 59L is capable of applying a hydraulic pressure lower than the hydraulic pressure supplied to the pressing cylinder 47 by the high-pressure circuit 59H to the pressing cylinder 47.

[0075] When positioning the pressing member 41 at the initial position (for example, the forward limit) before local pressing (Figs. 1(a) and 1(b)), the working fluid is supplied from the low-pressure circuit 59L to the head-side chamber 53h. When the pressure of the molten metal 109 is applied to the pressing member 41 (Figs. 2(a) and 2(b)), the pressing member 41 retracts against the hydraulic pressure from the low-pressure circuit 59L. When advancing the pressing member 41 to perform local pressing (Figs. 3(a) and 3(b)), the working fluid is supplied from the high-pressure circuit 59H to the head-side chamber 53h.

[0076] The configurations of the low-pressure circuit 59L and the high-pressure circuit 59H may be the same or completely different. Also, a part of the low-pressure circuit 59L and the high-pressure circuit 59H may be shared. Hereinafter, an example will be taken in which the configurations of the low-pressure circuit 59L and the high-pressure circuit 59H are the same as each other except for the difference in their pressures (and specific design matters resulting from the difference in pressures).

[0077] Figure 6 is a circuit diagram showing the configuration of a specific example of the hydraulic device 49.

[0078] The hydraulic circuit 59 shown in this figure may be regarded as either the low-pressure circuit 59L or the high-pressure circuit 59H. Also, components other than the hydraulic circuit 59 may be shared by the low-pressure circuit 59L and the high-pressure circuit 59H.

[0079] The hydraulic circuit 59 has, for example, the following components. An accumulator 61 as a hydraulic source for supplying hydraulic fluid to the pressure cylinder 47. A control valve 63 for controlling the flow of hydraulic fluid between the accumulator 61 and the pressure cylinder 47. A check valve 75 for controlling the flow of hydraulic fluid for accumulating the accumulator 61.

[0080] Also, the hydraulic device 49 has, in addition to the hydraulic circuit 59, for example, the following components. A back-pressure removal cylinder 65 for reducing the back pressure of the pressure cylinder 47. A pump 67 as a hydraulic source for accumulating the accumulator 61. A tank 69 for storing hydraulic fluid. Pressure sensors 71R and 71H for detecting the pressure of the pressure cylinder 47. A flow sensor 73 for detecting the flow rate of the hydraulic fluid discharged from the pressure cylinder 47. Various valves (77A, 77R, and 77H) for controlling the flow of hydraulic fluid in the hydraulic device 49. Note that these configurations may also be regarded as components of the hydraulic circuit 59.

[0081] In the following description of the hydraulic device 49, the description will generally be carried out in the following order. · Accumulator 61 · Control valve 63 · Check valve 75 · Back-pressure removal cylinder 65 · Pump 67 and tank 69 · Pressure sensors 71R and 71H and flow sensor 73 · Various valves (77A, 77R, and 77H) · Configuration of the hydraulic device 49 when two or more pressure cylinders 47 are provided

[0082] (Accumulator) The accumulator 61 may be constituted by an accumulator of an appropriate type such as a weight type, a spring type, a gas pressure type (including a pneumatic type), a cylinder type, a bladder type, etc. For example, the accumulator 61 is a gas pressure type, a cylinder type or a bladder type accumulator, and is accumulated by compressing a gas (for example, air or nitrogen) held in the accumulator 61.

[0083] The pressure of the accumulator 61 in the low pressure circuit 59L (it is assumed here that the pressure fluctuation due to the discharge of the working fluid can be ignored) is made lower than the pressure of the accumulator 61 in the high pressure circuit 59H. Thereby, the low pressure circuit 59L can supply a pressure lower than the pressure supplied by the high pressure circuit 59H to the pressurizing cylinder 47 (for example, the head side chamber 53h). The specific value of the pressure of the accumulator 61 may be set as appropriate. For example, the pressure of the accumulator 61 in the high pressure circuit 59H may be 13 MPa or more and 14 MPa or less.

[0084] (Control valve) The control valve 63 is configured to be able to allow and prohibit at least the communication between the accumulator 61 and the head side chamber 53h, for example. When the accumulator 61 and the head side chamber 53h are connected, for example, the working fluid is supplied from the accumulator 61 to the head side chamber 53h, and the pressurizing member 41 moves forward. Further, when the accumulator 61 of the low pressure circuit 59L is connected to the head side chamber 53h, for example, when the pressurizing member 41 retreats due to a surge pressure, the pressure is absorbed by the accumulator 61. Note that the absorption of the surge pressure (at least a part thereof) may be realized by compressing the working fluid without depending on the accumulator 61 of the low pressure circuit 59L.

[0085] Further, for example, by the cooperation of the control valve 63 of the low-pressure circuit 59L and the control valve 63 of the high-pressure circuit 59H, one of the accumulators 61 of the low-pressure circuit 59L and the accumulator 61 of the high-pressure circuit 59H can be selectively connected to the head-side chamber 53h. Therefore, the control valves 63 of both circuits may be regarded as a switching valve that selectively connects the low-pressure circuit 59L and the high-pressure circuit 59H to the head-side chamber 53h as a whole. Note that such a switching valve may be constituted by a valve having one valve body, unlike the illustrated example.

[0086] In the control valve 63, a specific configuration for allowing and prohibiting the connection between the accumulator 61 and the head-side chamber 53h may be appropriate. In the illustrated example, the control valve 63 is configured to function as a four-port three-position switching valve. In the first position, the accumulator 61 (or the pump 67) and the head-side chamber 53h are connected, and the tank 69 and the rod-side chamber 53r are connected. In the second position, conversely to the above, the accumulator 61 and the rod-side chamber 53r are connected, and the tank 69 and the head-side chamber 53h are connected. In the third position, any of the above connections is prohibited.

[0087] By setting the control valve 63 to the first position, for example, the hydraulic fluid can be supplied from the accumulator 61 to the head-side chamber 53h to advance the pressurizing member 41. At this time, the hydraulic fluid discharged from the rod-side chamber 53r is discharged to the tank 69. By setting the control valve 63 to the second position, for example, conversely to the above, the pressurizing member 41 can be retracted. Further, by setting the control valve 63 to the third position, for example, the pressurizing member 41 can be stopped.

[0088] Also, in the illustrated example, the control valve 63 is configured to function as a flow control valve capable of controlling the flow rate of the hydraulic fluid. This flow control valve is, for example, a flow control valve with pressure compensation that can keep the flow rate constant even when there is pressure fluctuation. The flow control valve is also, for example, a servo valve used in a servo mechanism and can continuously modulate the flow rate steplessly (continuously, to any value) in response to an input signal.

[0089] The control valve 63 as a flow control valve functions as a component of the meter-in circuit and / or the meter-out circuit, for example, when the hydraulic fluid is supplied from the accumulator 61 to the head side chamber 53h. Thereby, the forward speed of the pressurizing member 41 can be controlled, and local pressurization according to the solidification state can be performed.

[0090] The specific configuration of the control valve 63 that functions as the switching valve and / or the flow control valve as described above is also arbitrary. In the illustrated example, the control valve 63 is configured to have a main valve 63a and a pilot valve 63b. The main valve 63a communicates with the accumulator 61, the tank 69, the head side chamber 53h, and the rod side chamber 53r, and controls the flow of the hydraulic fluid in the three positions described above. The pilot valve 63b is driven by an electromagnetic drive method, introduces a pilot pressure to the main valve 63a, and controls the main valve 63a.

[0091] Note that the control valve 63 may have various configurations other than the illustrated example. For example, the control valve 63 may be a direct-acting valve or a pilot type check valve. Since the rod side chamber 53r does not necessarily need to be supplied with the hydraulic fluid as described above, the flow path and the valve for connecting the rod side chamber 53r to the accumulator 61 (or the pump 67) and the tank 69 may not be provided.

[0092] (Check Valve) The check valve 75 permits and prohibits the supply of the hydraulic fluid from the pump 67 to the hydraulic circuit 59. Thereby, for example, the accumulator 61 of the low pressure circuit 59L and the accumulator 61 of the high pressure circuit 59H can be selectively filled with the hydraulic fluid. Note that the valve having such a function may have a configuration other than a check valve, or may be a single valve shared by the low pressure circuit 59L and the high pressure circuit 59H. In the illustrated example, the check valve 75 is provided in a direction that permits the flow of the hydraulic fluid from the pump 67 to the accumulator 61 and prohibits the reverse flow, and prohibits both of the above flows by introducing a pilot pressure.

[0093] (Back-pressure removing cylinder) The back-pressure removing cylinder 65 is connected in the middle of a flow path connecting the control valve 63 (in another aspect, the rod-side chamber 53r) and the tank 69. When the working fluid flows from the rod-side chamber 53r to the tank 69, a part of it flows into the back-pressure removing cylinder 65. Thereby, for example, when the piston 55 (pressure applying member 41) advances, the increase in the pressure (back pressure) of the rod-side chamber 53r is reduced. As a result, the advancing speed of the pressure applying member 41 (in another aspect, the responsiveness of the pressure applying member 41) is improved.

[0094] The configuration of the back-pressure removing cylinder 65 may be an appropriate one. For example, the back-pressure removing cylinder 65 may be constituted by an accumulator. The description of the accumulator 61 described above may be applied to the back-pressure removing cylinder 65 as long as there is no contradiction or the like. Also, the capacity and pressure of the back-pressure removing cylinder 65 may be set as appropriate.

[0095] The pressure of the back-pressure removing cylinder 65 may be set relatively low. Thereby, the working fluid can be accommodated promptly. For example, in an aspect where the back-pressure removing cylinder 65 is a cylinder-type accumulator, the pressure when the piston 65a of the back-pressure removing cylinder 65 is located at the driving limit on the side where the working fluid is discharged (lower side in FIG. 6) is lower than the pressure of the accumulator 61 of the low-pressure circuit 59L.

[0096] The pressure when the piston 65a is located at the driving limit on the side where the working fluid is discharged is, for example, higher than the tank pressure. Thereby, when the working fluid does not flow from the control valve 63 to the tank 69, the piston 65a moves to the driving limit on the side where the working fluid is discharged. As a result, the working fluid in the back-pressure removing cylinder 65 is discharged to the tank 69.

[0097] (Pump and tank) The configurations of the pump 67 and the tank 69 may be various configurations, and for example, they may be known configurations. The pump 67 and / or the tank 69 may be shared by a hydraulic device other than the hydraulic device 49 of the pressurizing device 2A (for example, the hydraulic device of the injection device 9).

[0098] The pump 67 may be driven as necessary or may be constantly driven (the valves necessary in this case are not shown). The pump 67 contributes to the pressure accumulation of the accumulator 61, for example. Additionally, the pump 67 may, for example, supply the working fluid to the rod side chamber 53r in place of the accumulator 61 when retracting the piston 55 of the pressure cylinder 47 (the valves necessary in this case are not shown). Also, for example, the pump 67 may supply the working fluid to the head side chamber 53h in cooperation with the accumulator 61.

[0099] The tank 69 is, for example, of the atmosphere - open type. Therefore, the pressure in the flow path or the like connected to the tank 69 is basically approximately atmospheric pressure. The tank 69 contributes to the recovery of the working fluid discharged from the pressure cylinder 47 (rod side chamber 53r or head side chamber 53h), for example, as described above.

[0100] (Pressure sensor and flow rate sensor) The pressure sensor 71R detects the pressure in the rod side chamber 53r. The pressure sensor 71H detects the pressure in the head side chamber 53h. The control device 5 can specify, for example, the driving force generated by the pressure cylinder 47 based on the detected pressures in the rod side chamber 53r and the head side chamber 53h, and thus can specify the pressure applied to the molten metal by the pressurizing member 41. Note that it is also possible to specify the driving force applied by the pressure cylinder 47 to the pressurizing member 41 in the forward direction based only on the pressure in the head side chamber 53h, and the pressure sensor 71R may be omitted. The specific configurations of the pressure sensors 71R and 71H may be various configurations, for example, they may be of known configurations.

[0101] The flow sensor 73 detects the flow rate of the hydraulic fluid discharged from the rod side chamber 53r. Thereby, for example, the forward distance of the pressurizing member 41 can be detected. Such a sensor is particularly useful, for example, in an aspect where the sensor 43 for detecting the retreat of the pressurizing member 41 is not a position sensor. Note that the flow sensor 73 may not be provided. The specific configuration of the flow sensor 73 may be various configurations, and for example, it may be a known configuration.

[0102] (Various valves) The valves 77A, 77R, and 77H are used, for example, during the maintenance of the pressurizing device 2A. These valves may be configured by, for example, cocks that are manually opened and closed. Note that these valves may not be provided.

[0103] The valve 77A is provided in the flow path connecting the rod side chamber 53r and the head side chamber 53h. When the molding cycle is being performed, the valve 77A is closed. During maintenance, the valve 77A is opened and the hydraulic fluid is circulated. Thereby, air is bled from the pressurizing cylinder 47. As a result, the operation of the pressurizing cylinder 47 becomes stable.

[0104] The valve 77R is located between the rod side chamber 53r and the pressure sensor 71R. The valve 77H is located between the head side chamber 53h and the pressure sensor 71H. The valves 77R and 77H are open when the molding cycle is being performed.

[0105] Although not particularly shown, a check valve may be provided that allows the flow of the working fluid from the tank 69 to the rod side chamber 53r, prohibits the flow in the opposite direction, and allows both flows by introducing a pilot pressure. In this case, for example, with the pilot pressure introduced to the check valve, the working fluid is supplied from the low-pressure circuit 59L to the head side chamber 53h to move the pressurizing member 41 to the initial position. Then, before the pressurizing member 41 reaches the forward limit, the introduction of the pilot pressure is stopped to prohibit the discharge of the working fluid from the rod side chamber 53r. Thereby, the pressurizing member 41 can be stopped at an arbitrary position. That is, an arbitrary position in front of the retracted limit can be set as the initial position, and a forward force can be applied to the pressurizing member 41 at the initial position. When the pressurizing member 41 is pushed by the molten metal and retracts, the working fluid is replenished from the tank 69 to the rod side chamber 53r through the check valve. Thereafter, when performing local pressurization by supplying the working fluid from the high-pressure circuit 59H to the head side chamber 53h, the discharge of the working fluid from the rod side chamber 53r is allowed again by introducing the pilot pressure.

[0106] (Configuration of the hydraulic device when two or more pressurizing cylinders are provided) In the hydraulic device 49, a combination of components (for example, the pressurizing cylinder 47, the pressure sensors 71H and 71R, and the control valve 63) surrounded by a two-dot chain line is referred to as a unit 60. The hydraulic device 49 may have a plurality of units 60. That is, two or more pressurizing cylinders 47 (from another perspective, two or more pressurizing members 41) may be controllable independently of each other. As already mentioned, one pressurizing cylinder 47 may drive one pressurizing member 41 or may drive two or more pressurizing members 41. Also, two or more pressurizing members 41 may be driven by drive units 45 having different configurations from each other (for example, one having a pressurizing cylinder 47 and one not having a pressurizing cylinder 47).

[0107] (Operations related to injection and local pressurization) FIG. 7 is a diagram for explaining the operations related to injection and local pressurization. In the description of this figure, for the sake of convenience, the pressurizing device 2A may be expressed as if it were a component of the injection device 9, or local pressurization may be expressed as if it were a part of the injection process.

[0108] In FIG. 7, the horizontal axis represents time t, with the right side indicating a later time point. The left vertical axis represents velocity V, with the upper side indicating a higher speed. The right vertical axis represents pressure P, with the upper side indicating a higher pressure.

[0109] Line LV shows the change over time of the injection velocity (the velocity of the plunger 21). Line LP shows the change over time of the injection pressure. The injection pressure is assumed to be the pressure applied by the plunger 21 to the molten metal.

[0110] Line LC shows the change over time of the casting pressure. The casting pressure is, for example, the pressure of the molten metal in the product part 107a of the mold 101 after filling is completed, and in the description of this embodiment, it is distinguished from the injection pressure. In the following description, the casting pressure may sometimes refer only to the final pressure (end pressure) after it has risen. The pressure of the molten metal in the product part 107a strictly varies depending on the position within the product part 107a. The casting pressure shown here may be regarded as, for example, a representative value of the actual pressure in the product part 107a, or it may be regarded as the target value of the casting pressure set without considering such strictness.

[0111] Line LB shows the flash blow limit curve. The flash blow limit curve is a curve showing the change over time of the upper limit value of the pressure of the molding material (molten metal) that does not blow out flash. The control device 5 may calculate the combination of time and pressure indicated by the curve based on a calculation formula, or may identify it by referring to time-series data. The method for calculating the flash blow limit curve is known, and for example, it may be calculated by the calculation formula described in Japanese Patent Application Laid-Open No. 2019-13933.

[0112] The line LS indicates the change over time in the pressure obtained by converting the driving force with which the driving unit 45A drives the pressing member 41 toward the space 107 into the pressure that the pressing member 41 (its front end) can apply to the molten metal. Since it is the "pressure that can be applied", the line LS is shown even before the pressurization (for example, before the molten metal reaches the pressing member 41). After the pressurization starts (for example, after the molten metal reaches the pressing member 41), the pressure indicated by the line LS is the pressure that the pressing member 41 actually applies to the molten metal. Here, it is assumed that the pressing member 41 pressurizes the molten metal in a portion other than the product portion 107a or the outer peripheral portion of the product portion 107a. Therefore, the pressure indicated by the line LS does not coincide with the casting pressure (line LC), which is the representative value of the pressure of the product portion 107a or the target value of the representative value.

[0113] Note that the speed and pressure indicated by the lines LV, LP, LC, and / or LS may be regarded as indicating target values, or may be regarded as indicating actual values (for example, measured values detected by sensors). The target values may be set by user input or by the calculation of the control device 5.

[0114] The die-casting machine 1 performs, for example, low-speed injection (time points t0 to t1), high-speed injection (time points t1 to t2), and pressure increase and pressure holding (time points t2 to) in order. That is, as indicated by the line LV, the die-casting machine 1 performs low-speed injection in which the plunger 21 is advanced at a relatively low speed (speed V L ) from the viewpoint of preventing the entrainment of air in the molten metal at the initial stage of injection. Next, as indicated by the line LV, the die-casting machine 1 performs high-speed injection in which the plunger 21 is advanced at a relatively high speed (speed V H ) from the viewpoint of filling the molten metal without delay in solidification. Next, as indicated by the line LC, the die-casting machine 1 performs pressure increase to raise the molten metal in the product portion 107a from the viewpoint of eliminating sink marks in the molded product. After that, as indicated by the line LC, the die-casting machine 1 performs pressure holding to maintain the final pressure obtained by the pressure increase.

[0115] Generally, the casting pressure (line LC) is mainly realized by the injection pressure (line LP) applied by the plunger 21 to the molten metal. However, in the illustrated example, the proportion of the pressure (line LS) applied by the pressurizing member 41 to the molten metal contributing to the casting pressure is large. Specifically, it is as follows.

[0116] The injection pressure is relatively low during low-speed injection. Then, when high-speed injection starts (time point t1), the injection pressure also rises. Further, when the filling of the molten metal is almost completed (time point t2), since the molten metal loses its way, the injection pressure rises rapidly and reaches pressure P1. In the illustrated example, pressure P1 is lower than the casting pressure.

[0117] Generally, in a mode where the pressure P1 at the end of filling is lower than the casting pressure, the injection device 9 performs an operation for pressure boosting so that the injection pressure reaches a casting pressure higher than pressure P1. Such operations include, for example, the operation of switching the accumulator that supplies the working fluid to the head-side chamber 53h to an accumulator for pressure boosting, and the operation of supplying the working fluid behind the pressure boosting piston (see FIG. 12 described later).

[0118] However, in the illustrated example, the injection device 9 does not perform the operation for pressure boosting as described above. Instead, local pressurization is performed by the pressurizing device 2A, and thereby the casting pressure is realized. Specifically, in the illustrated example, when the injection pressure reaches pressure P1 (time point t2), the drive of the pressure cylinder 47 by the high-pressure circuit 59H is started, and thus local pressurization is started. At this time, the pressure P2 related to the local pressurization is, for example, higher than the casting pressure (target value) and lower than the flash blow limit curve.

[0119] Note that the pressure P2 may be set to be higher than the plastic deformation resistance. As the value of the plastic deformation resistance, for example, the yield point at the temperature of the molding material at the completion of the molten metal (when the upper yield point and the lower yield point appear, the former) may be used. The pressure P2 may be set by the user to be higher than the plastic deformation resistance, or may be set by the control device 5 having information on the plastic deformation resistance to be higher than the plastic deformation resistance. In the latter case, the control device 5 may acquire information on the plastic deformation resistance itself or information specifying the plastic deformation resistance according to the user's input.

[0120] The magnitude of the pressure P2 compared to the pressure P1 is arbitrary. For example, when the molded product is thin-walled, the pressure P2 may be set to be 1.1 times or more and 2.0 times or less of the pressure P1. When the molded product is medium-thick or thick-walled, the pressure P2 may be set to be 1.5 times or more and 4.0 times or less of the pressure P1. Of course, the ratio between the two may be outside the above range.

[0121] Before the local pressurization is started (before the time point t2), the pressure indicated by the line LS is smaller than the pressure P1 which is the injection pressure at the completion of filling (the maximum value of the injection pressure from another viewpoint). From another viewpoint, the driving force (hereinafter sometimes referred to as the initial force) that positions the pressurizing member 41 at the initial position (for example, the forward limit) is smaller than the force applied to the pressurizing member 41 when it is assumed that the pressure P1 is applied to the pressurizing member 41 from the front. Thereby, after the molten metal reaches the position of the pressurizing member 41, the pressurizing member 41 retreats at an appropriate time. In the present embodiment, the initial force is generated by supplying the working fluid from the low-pressure circuit 59L to the head-side chamber 53h. The initial force may be applied to the pressurizing member 41 at an appropriate timing, and in the illustrated example, it has been applied since the start of injection (time point t0).

[0122] FIG. 8 is a flowchart showing an example of the procedure of the process executed by the control device 5 to realize the above operation.

[0123] In step ST1, the control device 5 makes initial settings regarding various molding conditions based on the user's input operation or the like. Examples of the conditions set in this initial setting include values at appropriate times of the injection speed (line LV), injection pressure (line LP), casting pressure (line LC), and the pressure (line LS) applied by the pressurizing member 41 to the molten metal, as shown in FIG. 7. This value may include, for example, pressures P1 and P2. Also, values necessary for calculating the flash blow-off limit curve may be set.

[0124] In step ST2, the control device 5 determines whether the injection start condition is satisfied. The start condition may be, for example, that the clamping of the fixed mold 103 and the movable mold 105 is completed and information indicating that the molten metal has been supplied to the sleeve 19 is obtained. Then, the control device 5 waits until the start condition is satisfied (repeating step ST2), and when it determines that the start condition is satisfied, it proceeds to steps ST3 and ST6.

[0125] Steps ST3 to ST5 show the procedure of the process related to injection by the injection device 9. On the other hand, steps ST6 to ST10 show the procedure of the process related to local pressurization by the pressurizing device 2A. These processes are performed, for example, at least partially in parallel.

[0126] In step ST3, the control device 5 controls the drive unit 23 of the injection device 9 to advance the plunger 21. For example, the control device 5 controls a hydraulic device (not shown) of the injection device 9 so that the working fluid is supplied to the head side chamber 31h of the injection cylinder 27. Thereby, low-speed injection and high-speed injection are performed.

[0127] In step ST4, the control device 5 determines whether the injection pressure has reached the target value P1 at the time of filling completion. Then, when the determination is negative, the control device 5 waits (continuing high-speed injection), and when the determination is positive, it proceeds to step ST5.

[0128] In step ST5, the control device 5 stops the forward movement of the plunger 21. For example, the control device 5 stops supplying the working fluid to the head side chamber 31h. Also, at this time, the discharge of the working fluid from the head side chamber 31h may be prohibited so that the plunger 21 does not move backward due to the pressure from the molten metal.

[0129] In step ST6, the control device 5 controls the hydraulic device 49 so as to move the pressing member 41 (pressing pin) to the initial position (for example, the forward limit). That is, the control valve 63 of the low-pressure circuit 59L is controlled so that the working fluid is supplied from the accumulator 61 of the low-pressure circuit 59L to the head side chamber 53h of the pressure cylinder 47. Note that this step may be performed at an arbitrary timing as long as it is performed before the molten metal reaches the position of the pressing member 41. For example, it may be performed before step ST2.

[0130] In step ST7, the control device 5 determines, based on the signal from the sensor 43, whether or not the pressing member 41 has been pushed backward by the molten metal. Then, when the determination is negative, the control device 5 waits (repeats step ST7), and when the determination is positive, it proceeds to step ST8. Note that when the sensor 43 is not one that detects the presence or absence of backward movement like a limit switch, but is one that continuously detects a physical quantity related to backward movement like a position sensor or a pressure sensor, step ST7 may be a determination as to whether or not the detected amount (for example, the backward movement amount in the case of a position sensor) exceeds a predetermined threshold value.

[0131] In step ST8, the control device 5 controls the hydraulic device 49 so as to move the pressing member 41 forward. That is, the control device 5 controls the control valve 63 of the low-pressure circuit 59L and the control valve 63 of the high-pressure circuit 59H so that the working fluid is supplied from the accumulator 61 of the high-pressure circuit 59H to the head side chamber 53h instead of the accumulator 61 of the low-pressure circuit 59L. Thereby, local pressurization (pressure increase from another viewpoint) is performed.

[0132] In step ST9, the control device 5 determines whether or not the pressure applied by the pressurizing member 41 to the molten metal has reached the target pressure P2. When the determination is negative, the control device 5 waits (continuing the forward movement of the pressurizing member 41), and when the determination is positive, it proceeds to step ST10.

[0133] In step ST10, the control device 5 stops the forward movement of the pressurizing member 41. For example, the control device 5 stops supplying the working fluid to the head side chamber 53h. Thereby, pressure holding is performed. At this time, the discharge of the working fluid from the head side chamber 53h may be prohibited so that the pressurizing member 41 does not retreat due to the pressure from the molten metal. Alternatively, the working fluid may be replenished to the head side chamber 53h in an amount corresponding to the leakage of the working fluid.

[0134] Although not particularly shown, thereafter, when a predetermined condition (for example, elapse of a predetermined time) correlated with the solidification of the molten metal is satisfied, the control device 5 ends the pressure holding. For example, the control device 5 connects the head side chamber 53h to the tank 69 or the accumulator 61 of the low pressure circuit 59L. Further, the control device 5 performs control related to mold opening and the backward movement of the plunger 21 and the like. Thereafter, the control device 5 may return to step ST2 and repeat the injection cycle (molding cycle) until a predetermined end condition is satisfied.

[0135] As shown by the arrow connecting step ST4 and step ST7 in FIG. 8, making an affirmative determination in step ST4 may be a prerequisite for executing step ST7. From another viewpoint, the control device 5 may control the drive unit 45A to start the forward movement of the pressurizing member 41 on the condition that the pressure applied by the plunger 21 to the molten metal has reached a predetermined pressure (pressure P1 in the example of FIG. 8). The effects will be described in the summary of the first embodiment described later.

[0136] In an embodiment in which a plurality of pressurizing members 41 and a plurality of pressurizing cylinders 47 are provided, steps ST7 to S10 may be performed independently of each other for each pressurizing cylinder 47. Thereby, a plurality of pressurizing members 41 arranged at different positions can be controlled at appropriate timings respectively.

[0137] In step ST1, the pressure P2, which is the target pressure for local pressurization, may be set by the user or may be set by the control device 5 based on, for example, the target value of the casting pressure. In the former case, when the input pressure P2 is less than the target value of the casting pressure or the plastic deformation resistance, and / or when it exceeds the flash blowing limit curve, the control device 5 may give a warning to the user by means of a display device and / or an acoustic device, or may invalidate the input of such pressure P2. Further, when the control device 5 sets the pressure P2, the control device 5 may set the pressure P2 such that the pressure P2 is equal to or greater than the target value of the casting pressure or the plastic deformation resistance, and / or such that it is below the flash blowing limit curve.

[0138] (Summary of the First Embodiment) As described above, the local pressurization device 2A according to the first embodiment includes a pressurizing member 41 whose front end is exposed inside the mold (mold 101), and a drive unit 45A that applies a forward force to the pressurizing member 41. The pressurizing member 41 is positioned at an initial position (for example, the forward limit) in front of the retreat limit when the molding material (for example, molten metal) reaches the position of the pressurizing member 41, and is pushed by the molten metal and retreats from the initial position.

[0139] From another perspective, the molding machine (die-casting machine DC with a mold or die-casting machine 1) according to the first embodiment includes the above-described pressurization device 2A, a mold clamping device 7 that opens and closes and clamps the mold 101, and an injection device 9 that injects molten metal into the space 107.

[0140] From still another perspective, the molding method according to the first embodiment includes an injection step (see step ST3) and a local pressurization step (see step ST8). The injection step injects molten metal into the space 107. The local pressurization step advances a pressurizing member 41 whose front end is exposed in the space 107 to pressurize the molten metal in the space 107. The pressurizing member 41 is positioned at an initial position in front of the retreat limit when the molten metal reaches the position of the pressurizing member 41, and is pushed by the molten metal and retreats from the initial position.

[0141] Therefore, as described with reference to FIGS. 1(a) to 3(b) before the description of the first embodiment, various effects can be obtained. For example, the surge pressure can be absorbed by the retreat of the pressing member 41 to reduce the probability of burr generation, and the timing of the forward movement of the pressing member 41 can be optimized to reduce the probability of sink marks generation.

[0142] The drive unit 45A may position the pressing member 41 at the initial position while applying an initial forward force to the pressing member 41 when the molding material reaches the position of the pressing member 41. The initial force may be made smaller than the force applied to the pressing member 41 when it is assumed that the maximum pressure (pressure P1) during the injection process applied by the injection plunger (plunger 21) to the molding material is applied to the pressing member 41 from the front.

[0143] In this case, for example, the molten metal will cause the pressing member 41 to retreat against the initial force. In the process, the energy possessed by the molten metal is consumed. Therefore, the surge pressure is effectively absorbed.

[0144] The pressing device 2A may include a sensor 43 that detects the retreat of the pressing member 41, and a control device 5 that controls the drive unit 45A to start the forward movement of the pressing member 41 at a timing based on the detection of the retreat of the pressing member 41 by the sensor 43.

[0145] In this case, for example, the effect of optimizing the forward movement timing of the pressing member 41 as described above can be obtained. Note that the timing based on the detection of the retreat of the pressing member 41 is not limited to the timing immediately after detection, unlike the example of FIG. 8, and may be a timing after a predetermined time has elapsed from the detection point.

[0146] The control device 5 may control the drive unit 45A to start the forward movement of the pressing member 41 on the condition that the pressure applied by the plunger 21 to the molding material reaches a predetermined pressure (pressure P1 in the example of FIG. 8) (see the arrow from step ST4 to step ST7 in FIG. 8).

[0147] In this case, for example, the probability that the forward movement of the pressing member 41 starts before the filling of the molten metal is completed is reduced. As a result, for example, the sensitivity of detecting the backward movement of the pressing member 41 (step ST7) can be increased. For example, the backward movement amount until the limit switch is turned on can be decreased, or the backward movement amount (threshold value) when the control device 5 determines that the pressing member 41 has moved backward based on the detection value of the position sensor can be decreased, or the pressure increase amount (threshold value) when the control device 5 determines that the pressing member 41 has moved backward based on the detection value of the pressure sensor 71H can be decreased. This improvement in sensitivity is effective, for example, when it is difficult for the injection pressure to be transmitted to the position of the pressing member 41 due to the progress of solidification of the molten metal.

[0148] After the pressing member 41 moves backward from the initial position, it may apply a pressure equal to or higher than at least one of the casting pressure set by the control device 5 and the plastic deformation resistance of the molding material to the molding material.

[0149] In this case, for example, the pressure of the molding material is likely to be of an appropriate magnitude not only locally but also as a whole. As a result, for example, as described above, when pressure is increased by local pressing without increasing the pressure by the injection pressure, the quality of the product can be improved.

[0150] After the pressing member 41 moves backward from the initial position, it may apply a pressure below the flash blowing limit curve specified by the control device 5 to the molding material.

[0151] In this case, for example, the probability of flash generation around the pressing member 41 is reduced. From another perspective, while reducing the probability of flash generation, a relatively large local pressure can be applied to the molten metal as much as possible to improve the quality.

[0152] The drive unit 45 may include a hydraulic cylinder (pressure cylinder 47), an accumulator 61, a backpressure removal cylinder 65, and a servo valve (control valve 63). The pressure cylinder 47 is connected to the pressure member 41. The accumulator 61 is connected to a first cylinder chamber (head side chamber 53h) of the pressure cylinder 47 to which the working fluid is supplied when the pressure member 41 moves forward. The backpressure removal cylinder 65 is connected to a second cylinder chamber (rod side chamber 53r) of the pressure cylinder 47 from which the working fluid is discharged when the pressure member 41 moves forward. The control valve 63 controls the flow from the accumulator 61 to the head side chamber 53h.

[0153] In this case, for example, since a high pressure can be applied to the head side chamber 53h and the backpressure in the rod side chamber 53r can be quickly removed, the responsiveness of the pressure member 41 is improved. As a result, for example, in combination with the effect that the arrival of the molten metal can be appropriately detected by the sensor 43, the pressure member 41 can be advanced at an appropriate timing. Further, since the flow rate can be controlled by the control valve 63 as the servo valve, the probability that the pressure member 41 advances excessively due to the use of the accumulator 61 and the backpressure removal cylinder 65 is reduced.

[0154] When the diameter of the front end of the pressure member 41 is d and the diameter of the front end of the plunger 21 is D, d / D may be 0.2 or more and 0.5 or less.

[0155] In this case, for example, since d / D is 0.5 or less, the pressure applied by the pressure member 41 to the molten metal can be made relatively large with respect to the driving force generated by the drive unit 45A that drives the pressure member 41, and the burden on the drive unit 45A can be reduced. Also, for example, since d / D is 0.2 or more, a relatively large volume for pushing the molding material can be ensured, and the effect of local pressurization can be improved.

[0156] <Second Embodiment> Figs. 9(a) and 9(b) are cross-sectional views showing the configuration of the pressurizing device 2B according to the second embodiment. Fig. 9(a) corresponds to Fig. 1(b) and shows a state where the molten metal has not reached the position of the pressurizing member 41 and the pressurizing member 41 is located at the initial position (forward limit). Fig. 9(b) corresponds to Fig. 2(b) and shows a state where the molten metal has reached the position of the pressurizing member 41 and the pressurizing member 41 has retreated.

[0157] In the pressurizing device 2B, an elastic member 45B is used as the driving unit 45. Before the molten metal reaches the pressurizing member, the pressurizing member 41 is pushed forward (toward the space 107) by the restoring force of the elastic member 45B and is located at the forward limit. When the pressurizing member 41 is located at the forward limit, the elastic member 45B may be in a state where it generates a restoring force (a state where deformation remains), or may be in a state where it generally does not generate a restoring force.

[0158] Thereafter, when the molten metal 109 reaches the position of the pressurizing member 41, the pressurizing member 41 retreats. As the pressurizing member 41 retreats, the elastic member 45B increases its restoring force. Then, the pressurizing member 41 stops at a position where the force received from the molten metal and the restoring force of the elastic member 45B are balanced (here, the influence of friction force, etc. is ignored). Note that, different from the above, the pressurizing member 41 may stop by contacting a stopper (not shown) that defines its retreat limit.

[0159] The specific configuration of the elastic member 45B may be appropriate. In the illustrated example, the elastic member 45B is constituted by a coiled spring, the front end of which contacts the pressurizing member 41, and the rear end of which contacts the fixed mold 103 (or a member fixed to the fixed mold 103). And the elastic member 45B generates a restoring force by compressive deformation. Other specific examples of the elastic member 45B include one or more leaf springs (for example, laminated disc springs) (the same applies to other embodiments described later). Incidentally, for the sake of description, the pressurizing device 2B does not have a driving unit that actively generates a driving force, such as a pressurizing cylinder 47.

[0160] Also in this embodiment, the pressing device 2B includes a pressing member 41 whose front end is exposed inside the mold (mold 101) (space 107), and a driving part (elastic member 45B) that applies a forward force to the pressing member 41. The pressing member 41 is located at an initial position (forward limit) in front of the retraction limit when the molding material (molten metal 109) reaches the position of the pressing member 41, and is pushed by the molten metal 109 and retracts from the forward limit.

[0161] Therefore, at least some of the effects described before the description of the first embodiment are achieved. For example, the surge pressure can be absorbed. The pressing member 41 can apply a pressure higher than the pressure of the molten metal after the surge pressure has subsided to the molten metal by the elastic member 45B absorbing the surge pressure. Thereby, the effect of local pressing can be obtained.

[0162] As shown in this embodiment, the driving part (45) may include an elastic member 45B that applies a forward restoring force to the pressing member 41.

[0163] In this case, for example, compared with a mode of absorbing the surge pressure by compressing a fluid (this mode is also included in the technology according to the present disclosure), the surge pressure can be sufficiently absorbed by the elastic deformation of the elastic member 45B. Also, the need to use a fluid is reduced, so members such as seals can be omitted. Furthermore, since local pressing is performed on the molten metal after the surge pressure has subsided by utilizing the absorption of the surge pressure, energy can be saved.

[0164] <Third Embodiment> FIG. 10 is a cross-sectional view showing the configuration of the pressing device 2C according to the third embodiment, corresponding to FIG. 1(b). This figure shows a state where the molten metal has not reached the position of the pressing member 41 and the pressing member 41 is located at the initial position (forward limit).

[0165] The drive unit 45C of the pressurizing device 2C is, simply put, a combination of the pressurizing cylinder 47 of the first embodiment and the elastic member 45B of the second embodiment. Specifically, the elastic member 45B and the pressurizing cylinder 47 are provided so as to be able to apply forces in parallel to the pressurizing member 41. Here, "in parallel" refers to the application of force, not the positional relationship.

[0166] Specifically, in the illustrated example, as in the first embodiment, the piston rod 57 of the pressurizing cylinder 47 is connected to the pressurizing member 41. The elastic member 45B is constituted by a coiled spring and is arranged concentrically with respect to the piston rod 57. Similar to the second embodiment, the front end of the elastic member 45B abuts against the pressurizing member 41, the rear end abuts against the fixed mold 103 (or a member fixed to the fixed mold 103), and a restoring force is generated by compression deformation.

[0167] Although not particularly shown, the drive unit 45C has a hydraulic device that supplies working fluid to the pressurizing cylinder 47 and the like. This hydraulic device is obtained by removing the low-pressure circuit 59L from the hydraulic device 49 shown in FIGS. 5 and 6. As will be described below, this is because the elastic member 45B takes the place of the low-pressure circuit 59L.

[0168] When injection is being performed (time points t0 to t2 in FIG. 7), the hydraulic device connects, for example, the rod-side chamber 53r and the head-side chamber 53h to the tank 69. Therefore, the pressurizing member 41 is pushed forward by the restoring force of the elastic member 45B and is located at the forward limit (initial position). When the molten metal reaches the position of the pressurizing member 41, as in the second embodiment, the pressurizing member 41 retreats with the deformation of the elastic member 45B. At this time, the surge pressure may be absorbed. Further, when the pressurizing member 41 retreats, as in the first embodiment, the forward movement of the pressurizing member 41 is started by the high-pressure circuit 59H and the pressurizing cylinder 47, and local pressurization is performed (see steps ST7 to ST10 in FIG. 8).

[0169] Incidentally, when the pressure member 41 is moved forward by the elastic member 45B before local pressurization, as described in the first embodiment, the discharge of the working fluid from the rod side chamber 53r may be prohibited by a pilot type check valve or the like, and the pressure member 41 may be stopped before reaching the forward limit. That is, the initial position may be a position other than the forward limit.

[0170] As described above, also in the present embodiment, the local pressurizing device 2C has a pressure member 41 whose front end is exposed inside the mold (mold 101), and a drive unit 45C that applies a forward force to the pressure member 41. The pressure member 41 is located at an initial position (for example, the forward limit) in front of the retraction limit when the molding material (for example, molten metal) reaches the position of the pressure member 41, and is pushed by the molten metal and retracts from the initial position.

[0171] Therefore, the effects described before the description of the first embodiment are achieved. For example, the surge pressure can be absorbed, and the start timing of local pressurization can be optimized.

[0172] Also, as shown in the present embodiment, the drive unit 45C may include a hydraulic cylinder (pressurizing cylinder 47) that applies a driving force to the pressure member 41, and an elastic member 45B that applies a forward restoring force to the pressure member 41. The pressurizing cylinder 47 and the elastic member 45B may be provided so as to be able to apply forces to the pressure member 41 in parallel with each other.

[0173] In this case, for example, since the elastic member 45B can position the pressure member 41 at the initial position while applying a forward force to the pressure member 41, the low-pressure circuit 59L of the first embodiment becomes unnecessary. As a result, the hydraulic device is simplified.

[0174] <Fourth Embodiment> FIG. 11 is a cross-sectional view showing the configuration of the pressurizing device 2D according to the fourth embodiment, corresponding to FIG. 1(b). This figure shows a state in which the molten metal has not reached the position of the pressure member 41 and the pressure member 41 is located at the initial position.

[0175] The drive unit 45D of the pressurizing device 2D is, briefly speaking, a combination of the pressurizing cylinder 47 of the first embodiment and the elastic member 45B of the second embodiment, similar to the third embodiment. And, similar to the third embodiment, before the molten metal reaches the pressurizing member 41, instead of the low-pressure circuit 59L, the elastic member 45B pushes the pressurizing member 41 forward to position the pressurizing member 41 at the initial position (for example, the forward limit). However, in the third embodiment, the elastic member 45B and the pressurizing cylinder 47 were provided so as to be able to apply force to the pressurizing member 41 in parallel with each other, whereas in this embodiment, the elastic member 45B and the pressurizing cylinder 47 are provided so as to be able to apply force to the pressurizing member 41 in series with each other.

[0176] Specifically, in the illustrated example, similar to the first embodiment, in the pressurizing cylinder 47, the piston rod 57 is connected to the pressurizing member 41. The elastic member 45B is constituted by a coil spring, the front end abuts against the rear end of the cylinder member 53, and the rear end abuts against the fixed mold 103 (or a member fixedly attached to the fixed mold 103). And the elastic member 45B generates a restoring force by compression deformation. As a mode different from the illustrated example, for example, there is a mode in which the cylinder member 53 is fixed to the fixed mold 103 and the elastic member 45B is interposed between the piston rod 57 and the pressurizing member 41.

[0177] Although not particularly illustrated, the drive unit 45D has a hydraulic device that supplies the operating fluid to the pressurizing cylinder 47 and the like. This hydraulic device is the same as the hydraulic device 49 shown in FIGS. 5 and 6 with the low-pressure circuit 59L removed, similar to the third embodiment.

[0178] When injection is being performed (at time points t0 to t2 in Fig. 7), the hydraulic device positions, for example, the piston 55 at an appropriate position (e.g., the retracted limit) with respect to the cylinder member 53. Note that the rod-side chamber 53r and the head-side chamber 53h may, for example, be prohibited from the inflow and outflow of the working fluid. Then, the pressurizing member 41 is pushed forward together with the pressurizing cylinder 47 by the restoring force of the elastic member 45B and is positioned at the forward limit. When the molten metal reaches the position of the pressurizing member 41, the pressurizing member 41 retreats along with the deformation of the elastic member 45B together with the pressurizing cylinder 47. At this time, the surge pressure may be absorbed. Further, when the pressurizing member 41 retreats, as in the first embodiment, the forward movement of the pressurizing member 41 is started by the high-pressure circuit 59H and the pressurizing cylinder 47, and local pressurization is performed (see steps ST7 to ST10). Although not particularly shown, a stopper for defining the retracted limit of the cylinder member 53 with respect to the fixed mold 103 may be provided.

[0179] As described above, Fig. 11 shows, for example, a state where the pressurizing member 41 is located at the initial position. In the illustrated example, the pressurizing cylinder 47 can further advance the pressurizing member 41 from the initial position. Therefore, Fig. 11 shows an example of the initial position that is not the forward limit with respect to the pressurizing member 41. When local pressurization is performed, the control may be performed so that the pressurizing member 41 advances forward from the initial position, or such control may not be performed. Note that, unlike the illustrated example, when the pressurizing member 41 is in the illustrated position, the illustrated position may be the forward limit by the pressurizing member 41 (or a member fixed to the pressurizing member 41) abutting against a stopper provided on the fixed mold 103 (or a member fixed to the fixed mold 103).

[0180] As described above, also in this embodiment, the local pressurizing device 2D includes a pressurizing member 41 whose front end is exposed inside the mold (mold 101) (space 107), and a drive unit 45D that applies a forward force to the pressurizing member 41. The pressurizing member 41 is located at an initial position (e.g., the forward limit) in front of the retracted limit when the molding material (e.g., molten metal) reaches the position of the pressurizing member 41, and is pushed by the molten metal and retreats from the initial position.

[0181] Therefore, the effects described before the description of the first embodiment are achieved. For example, it is possible to absorb the surge pressure or optimize the start timing of the local pressurization.

[0182] Also, as shown in the present embodiment, the drive unit 45D may include a hydraulic cylinder (pressurizing cylinder 47) that applies a driving force to the pressurizing member 41, and an elastic member 45B that applies a restoring force in the forward direction to the pressurizing member 41. The pressurizing cylinder 47 and the elastic member 45B may be provided so as to be able to apply forces to the pressurizing member 41 in series with each other.

[0183] In this case, for example, similar to the third embodiment, since the elastic member 45B can position the pressurizing member 41 at the initial position, the low-pressure circuit 59L of the first embodiment becomes unnecessary. As a result, the hydraulic device is simplified.

[0184] <Fifth Embodiment> FIG. 12 is a schematic diagram showing the configuration of the die-casting machine DCE with a mold according to the fifth embodiment.

[0185] The pressurizing device 2E (drive unit 45E) according to the present embodiment is configured to drive the pressurizing member 41 by the pressurizing cylinder 47, similar to the first embodiment. However, in the present embodiment, the supply mode of the working fluid to the pressurizing cylinder 47 is different from that of the first embodiment. Specifically, in the hydraulic device 49E of the present embodiment, the head side chamber 53h of the pressurizing cylinder 47 and the head side chamber 31h of the injection cylinder 27E are communicated with each other by the communication passage 83, and a pressure equivalent to the pressure applied to the head side chamber 31h is supplied to the head side chamber 53h. More specifically, for example, it is as follows.

[0186] (Configuration of Injection Device and Pressurizing Device) In this embodiment, the drive unit 23E that drives the plunger 21 has an injection cylinder 27E. Further, the drive unit 23E is configured to be able to increase the pressure by applying a pressure higher than the pressure applied to the head-side chamber 31h by the time of the injection process in the narrow sense (time points t0 to t2 in FIG. 7) to the head-side chamber 31h. As such a drive unit 23E, for example, there are a mode having a pressure-increasing type injection cylinder (illustrated example), and a mode having an accumulator used only for pressure increase among injection and pressure increase. Note that the drive unit 23E may be a hybrid type that combines an injection cylinder and an electric motor. Hereinafter, the illustrated example (pressure-increasing type injection cylinder 27E) will be taken as an example for explanation.

[0187] Similar to the injection cylinder 27 shown in FIG. 1(a), the injection cylinder 27E has a cylinder member 31E, a piston 33, and a piston rod 37. However, the cylinder member 31E has a small-diameter cylinder portion 31x and a large-diameter cylinder portion 31y that communicates with the rear (right side in FIG. 12) of the small-diameter cylinder portion 31x and has a larger diameter than the small-diameter cylinder portion 31x, and the small-diameter cylinder portion 31x corresponds to the cylinder member 31 in FIG. 1(a). Further, the injection cylinder 27E has a pressure-increasing piston 35 behind the piston 33.

[0188] The pressure-increasing piston 35 has a small-diameter portion 35x that slides in the small-diameter cylinder portion 31x and a large-diameter portion 35y that slides in the large-diameter cylinder portion 31y. The large-diameter portion 35y partitions the large-diameter cylinder portion 31y into a front-side chamber 31a in the front and a rear-side chamber 31b in the rear. The area of the pressure-increasing piston 35 that receives the pressure from the front (head-side chamber 31h) is smaller than the area that receives the pressure from the rear (rear-side chamber 31b). Therefore, the pressure-increasing piston 35 can apply a pressure higher than that of the rear-side chamber 31b to the head-side chamber 31h in a state where the front-side chamber 31a is depressurized.

[0189] In the pressurizing cylinder 47, the ratio of the area where the piston 55 receives pressure from the head side chamber 53h to the area where the pressurizing member 41 receives pressure from the front is substantially the same as the ratio of the area where the piston 33 receives pressure from the head side chamber 31h to the area where the plunger 21 receives pressure from the front in the injection cylinder 27E. Therefore, for example, when equal pressures are applied to the head side chamber 53h and the head side chamber 31h, the pressurizing member 41 and the plunger 21 can apply equal pressures to the molten metal.

[0190] In addition to the illustrated example, examples of the pressure boosting type injection cylinder include those having a configuration in which the cylinder member in which the piston 33 slides and the cylinder member in which the pressure boosting piston 35 slides are separated. In short, in the pressure boosting type injection cylinder, it is sufficient that the area where the pressure boosting piston 35 receives the pressure of the head side chamber 31h is smaller than the area where it receives pressure from the opposite side. Also, just in case, the hydraulic device 49E does not have, for example, a low pressure circuit 59L and a high pressure circuit 59H (in other words, a dedicated accumulator 61 for the pressurizing device 2E). Further, the pressurizing device 2E does not have, for example, a sensor 43 for detecting the retreat of the pressurizing member 41.

[0191] (Operations of the injection device and the pressurizing device) In the injection process (time points t0 to t2 in FIG. 7), the control device 5 opens the valve 81A and supplies the working fluid from the accumulator 79 to the head side chamber 31h of the injection cylinder 27E. The switching of the injection speed is realized by a meter-out circuit (example in the figure, reference numerals omitted) and / or a meter-in circuit.

[0192] The head side chamber 53h of the pressurizing cylinder 47 communicates with the head side chamber 31h at an appropriate time before the completion of the filling of the molten metal (for example, at the start of injection). Therefore, the pressure of the accumulator 79 is also applied to the head side chamber 53h. As a result, the pressurizing member 41 is pushed forward and positioned at the initial position (for example, the forward limit).

[0193] When the molten metal is substantially filled in the space 107 of the mold 101, the pressure of the molten metal reaching the position of the pressurizing member 41 rises. As described above, the pressurizing member 41 can apply the same pressure as the plunger 21 to the molten metal. Therefore, for example, when surge pressure occurs, the pressurizing member 41 retreats.

[0194] When a predetermined pressure increasing condition is satisfied, the control device 5 opens the valve 81B and supplies the working fluid from the accumulator 79 to the rear chamber 31b of the injection cylinder 27E. As described above, the pressure increasing piston 35 applies a pressure higher than the pressure in the rear chamber 31b to the head side chamber 31h. The valve 81A either closes itself or is closed by the control device 5. As a result, the pressure applied by the plunger 21 to the molten metal increases, and pressure increase (from the time point t2 in FIG. 7) is performed. Different from FIG. 7, the injection pressure (line LP) increases so as to approach the casting pressure (line LC).

[0195] At this time, the communication between the head side chamber 53h and the head side chamber 31h is continued. Therefore, the pressure in the pressurized head side chamber 31h is also applied to the head side chamber 53h. As a result, similar to the pressure increase performed by the plunger 21, the pressurizing member 41 can perform local pressurization.

[0196] In order for the above-described operation to be preferably performed, various valves or pressure removing cylinders (both not shown) may be appropriately provided in the communication passage 83. Further, as the solidification of the molten metal progresses, the pressure of the molten metal etc. is different between the position of the plunger 21 and the position of the pressurizing member 41, so that the magnitudes and / or timings of the pressures applied by both to the molten metal are different from each other, and the dimensions may be appropriately set, or the valves in the communication passage 83 may be controlled.

[0197] As described above, also in the present embodiment, the local pressurizing device 2E has a pressurizing member 41 whose front end is exposed inside the mold (mold 101) and a drive unit 45E that applies a forward force to the pressurizing member 41. The pressurizing member 41 is located at an initial position (for example, the forward limit) in front of the retreat limit when the molding material (for example, molten metal) reaches the position of the pressurizing member 41, and is pushed by the molten metal and retreats from the initial position.

[0198] Therefore, the effects described before the description of the first embodiment are achieved. For example, the surge pressure can be absorbed.

[0199] Also, as shown in this embodiment, the drive unit 45E may have a hydraulic cylinder (pressure cylinder 47) connected to the pressure member 41. The first cylinder chamber (head side chamber 53h) to which the working fluid is supplied when the pressure member 41 moves forward in the pressure cylinder 47 may communicate with the head side chamber 31h to which the working fluid is supplied when the plunger 21 moves forward in the injection cylinder 27E that drives the injection plunger (plunger 21).

[0200] In this case, for example, at least one of the driving force for positioning the pressure member 41 at the initial position before the molten metal reaches the position of the pressure member 41 and the driving force for locally pressurizing by moving the pressure member 41 forward after the pressure member 41 has retreated (both in the illustrated example) can be obtained by the supply of the working fluid from the accumulator 79 for injection. Also, for example, in the mode of increasing the pressure in the head side chamber 31h to start the pressure increase by the plunger 21, the start timing of the local pressurization can be made to follow the start timing of the pressure increase. As a result, the timing of the local pressurization is optimized.

[0201] Note that, different from the illustrated example, the pressure cylinder 47 may be positioned at the initial position with the working fluid supplied from the low-pressure circuit 59L in a state blocked from the injection cylinder 27E, and then, when performing local pressurization, the pressure of the pressurized head side chamber 31h may be supplied. Conversely, the pressure cylinder 47 may be positioned at the initial position with the working fluid supplied from the accumulator 79 that supplies the working fluid to the head side chamber 31h, and then, when performing local pressurization, the working fluid may be supplied from the high-pressure circuit 59H.

[0202] <Another example of the position of the pressure member> FIG. 13 is a diagram showing an example different from the examples illustrated so far regarding the position of the pressure member 41.

[0203] In the description of the first embodiment, it was described that the pressing member 41 may press the molten metal in any part of the space 107 (such as the product part 107a, the overflow 107b, and the runner 107e). In the example of FIG. 13, the pressing member 41 is arranged to press the molten metal in the runner 107e.

[0204] Specifically, in the illustrated example, the runner 107e is provided such that its flow direction intersects (for example, is orthogonal to) the sleeve 19. From another perspective, in the illustrated example, the flow direction of the runner 107e is in the vertical direction. The sleeve 19 communicates with the lower side surface of the runner 107e. The upper part of the runner 107e communicates with the product part 107a via a gate (reference numeral omitted).

[0205] The pressing member 41 is arranged, for example, on the side opposite to the product part 107a with respect to the runner 107e and is provided so as to be movable in the flow direction of the runner 107e. The position of the pressing member 41 shown in FIG. 13 is, for example, the initial position before the molten metal reaches the pressing member 41. The initial position may be the forward limit of the pressing member 41 or may not be the forward limit. In other words, the pressing member 41 may not be able to penetrate into the runner 107e or may be able to penetrate. Note that, unlike the illustrated example, the pressing member 41 may be provided so as to be able to advance and retreat in a direction different from the flow direction of the runner 107e.

[0206] The pressing member 41 that presses the runner 107e may be combined with the drive part 45 of any of various embodiments. For example, as the drive part 45, the drive part 45D (FIG. 11) of the fourth embodiment may be used. In this case, similar to FIG. 11, the illustrated initial position may be the position when the cylinder member 53 is at the forward limit with respect to the mold 101 and the piston 55 is at a position behind the forward limit with respect to the cylinder member 53 (for example, the retracted limit). Then, in local pressing, the pressing member 41 may advance upward from the illustrated position.

[0207] In the above embodiments, the metal mold 101 is an example of a mold. The die-casting machine DC or DCE with die or the die-casting machine 1 is an example of a molding machine. The molten metal 109 is an example of a molding material. The plunger 21 is an example of an injection plunger. The pressure cylinder 47 is an example of a hydraulic cylinder. The head side chamber 53h is an example of a first cylinder chamber. The rod side chamber 53r is an example of a second cylinder chamber. The control valve 63 is an example of a servo valve.

[0208] The present invention is not limited to the above-described embodiment and modifications, and may be implemented in various forms.

[0209] The molding machine is not limited to a die-casting machine. For example, the molding machine may be another metal molding machine, an injection molding machine for molding resin, or a molding machine for molding a material in which thermoplastic resin or the like is mixed with wood powder. The molding machine is not limited to horizontal clamping and horizontal injection, and may be, for example, vertical clamping and vertical injection, vertical clamping and horizontal injection, or horizontal clamping and vertical injection. The die-casting machine is not limited to a cold chamber machine, and may be, for example, a hot chamber machine. The operating fluid is not limited to oil, and may be, for example, water.

[0210] The injection is not limited to low-speed injection and high-speed injection, and may be, for example, laminar flow filling at a low speed. The pressurizing member for localized pressurization may also be used as an ejection pin for pushing out a molded product formed by solidifying the molding material from the mold. As described in the description of the embodiment, the drive unit may be electrically driven. For example, a linear motor (including a voice coil motor) may be provided instead of the pressurizing cylinder.

[0211] The configurations of the multiple embodiments may be combined as appropriate. For example, in an embodiment in which multiple pressure members 41 are provided, different configurations of the drive units 45 may be applied to a single die casting machine. [Explanation of symbols]

[0212] DC…-type die-casting machine (molding machine), 1…die-casting machine (molding machine), 2…local pressurizing device, 5…control device, 9…injection device, 41…pressurizing member, 43…sensor, 45…drive unit, 47…pressurizing cylinder, 101…mold, 107…space (inside the mold).

Claims

1. a pressing member with its front end exposed inside the mold; a driving unit that applies a forward force to the pressing member; and has, the pressing member is positioned at an initial position in front of the retraction limit when the molding material reaches the position of the pressing member, and is pushed by the molding material and retracts from the initial position, the driving unit has a hydraulic cylinder connected to the pressing member, the pressing member and the piston or the cylinder member accommodating the piston in the hydraulic cylinder are not relatively movable forward and backward, the initial position is the forward limit of the pressing member Local pressurizing device.

2. a pressing member with its front end exposed inside the mold; a driving unit that applies a forward force to the pressing member; and has, the pressing member is positioned at an initial position in front of the retraction limit when the molding material reaches the position of the pressing member, and is pushed by the molding material and retracts from the initial position, the driving unit is, a hydraulic cylinder connected to the pressing member; a first accumulator that absorbs the pressure of the working fluid discharged from the hydraulic cylinder when the pressing member retracts; and has Local pressurizing device.

3. a pressing member with its front end exposed inside the mold; a driving unit that applies a forward force to the pressing member; and has, the pressing member is positioned at an initial position in front of the retraction limit when the molding material reaches the position of the pressing member, and is pushed by the molding material and retracts from the initial position, the driving unit has a hydraulic cylinder connected to the pressing member, the second cylinder chamber of the hydraulic cylinder, whose volume expands when the pressing member retracts, is open to the atmosphere Local pressurizing device.

4. when the molding material reaches the position of the pressing member, the driving unit positions the pressing member at the initial position with an initial forward force applied to the pressing member, the initial force is smaller than the force applied to the pressing member when it is assumed that the maximum pressure during the injection process applied by the injection plunger to the molding material is applied to the pressing member from the front The local pressurizing device according to any one of claims 1 to 3.

5. a sensor for detecting the retraction of the pressing member; a control device that controls the driving unit to start the forward movement of the pressing member at a timing based on the detection of the retraction of the pressing member by the sensor; The local pressurizing device according to any one of claims 1 to 4, further comprising.

6. The control device controls the drive unit to start the forward movement of the pressing member on the condition that the pressure applied by the injection plunger to the molding material reaches a predetermined pressure. The local pressurizing device according to claim 5.

7. After the pressing member retreats from the initial position, the pressing member applies a pressure equal to or higher than at least one of the casting pressure set by the control device and the plastic deformation resistance of the molding material to the molding material. The local pressurizing device according to any one of claims 1 to 6.

8. After the pressing member retreats from the initial position, the pressing member applies a pressure below the flash blow limit curve specified by the control device to the molding material. The local pressurizing device according to any one of claims 1 to 7.

9. The drive unit includes a second accumulator connected to a first cylinder chamber of the hydraulic cylinder where the working fluid is supplied when the pressing member moves forward, a back pressure removal cylinder connected to a second cylinder chamber of the hydraulic cylinder where the working fluid is discharged when the pressing member moves forward, and a servo valve that controls the flow from the second accumulator to the first cylinder chamber. The local pressurizing device according to claim 1 or 2.

10. The drive unit includes an elastic member that applies a forward restoring force to the pressing member. The local pressurizing device according to any one of claims 1 to 9.

11. The hydraulic cylinder and the elastic member are provided so as to be able to apply forces to the pressing member in parallel with each other. The local pressurizing device according to claim 10.

12. The hydraulic cylinder and the elastic member are provided so as to be able to apply forces to the pressing member in series with each other. The local pressurizing device according to claim 10.

13. A first cylinder chamber of the hydraulic cylinder where the working fluid is supplied when the pressing member moves forward communicates with a head side chamber of an injection cylinder that drives the injection plunger where the working fluid is supplied when the injection plunger moves forward. The local pressurizing device according to any one of claims 1 to 8.

14. When the diameter of the front end of the pressing member is d and the diameter of the front end of the injection plunger is D, d / D is 0.2 or more and 0.5 or less. The local pressurizing device according to any one of claims 1 to 13.

15. The local pressurizing device according to any one of claims 1 to 14, a mold clamping device that opens and closes and clamps the mold, and an injection device that injects the molding material into the mold. A molding machine having

16. An injection step of injecting a molding material into the mold, A local pressurization step of advancing a pressurizing member with its front end exposed inside the mold to pressurize the molding material inside the mold, having The pressurizing member is located at an initial position in front of the retreat limit when the molding material reaches the position of the pressurizing member, and is pushed by the molding material and retreats from the initial position. The pressurizing member is connected to a hydraulic cylinder. A molding method of absorbing the pressure of the working fluid discharged from the hydraulic cylinder by an accumulator when the pressurizing member retreats. ​

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