Device, mold, injection molding machine, manufacturing unit, method for manufacturing a resin molded product, and valve unit

Abstract

This invention relates to an apparatus, a mold, an injection molding machine, a manufacturing unit, a method for manufacturing resin-molded products, and a valve unit. The apparatus includes a first flow path component configured to define a first section of a flow path, a second flow path component configured to define a second section of a flow path, and a valve unit configured to suppress backflow in the flow path. The first and second sections are connected via the valve unit. The valve unit includes a first valve seat portion and a movable valve body. The first valve seat portion is configured to close the flow path when the valve body abuts against it. The first valve seat portion is configured to abut against the first flow path component and is made of a material with a higher hardness than the material constituting the first flow path component.

Description

Technical Field

[0001] The present invention relates to a flow path for molten resin that can suppress backflow in equipment for processing molten resin (e.g., injection molding machine). Background Technology

[0002] To date, injection molding is known as a method for manufacturing resin products. In injection molding, molten resin is injected into a cavity within a mold using a screw, plunger, or similar means. The molten resin then cools and solidifies within the mold. After solidification, the mold is opened to remove the molded product. By repeating this series of operations from injecting molten resin to removing the molded product, resin-molded products can be produced continuously in large quantities. Equipment used to perform injection molding, such as pre-plasticizing (hereinafter referred to as pre-plasticizing) molding machines or in-line screw molding machines, is known.

[0003] For example, a pre-plasticized injection molding machine includes a plasticizing mechanism comprising a screw and a plunger for injecting molten resin material. The screw and plunger are connected via a flow path, with a valve positioned in the middle of the flow path. Molten resin extruded from the screw into the flow path is supplied to the plunger side through the open valve. Subsequently, by closing the valve and advancing the plunger, the molten resin is injected into the mold cavity. At this time, closing the valve prevents resin backflow to the screw side and ensures appropriate injection pressure. As a valve capable of opening and closing the molten resin flow path, one method involves operating it by supplying power to the opening / closing mechanism from the outside; however, simpler structural methods have also been investigated. Japanese Patent Application Publication Nos. 2004-255588 and 2004-330672 describe backflow prevention valves that perform opening / closing operations by moving the valve body using the pressure difference between the molten resin before and after the valve.

[0004] Compared to systems that supply power to the opening / closing mechanism from the outside, backflow prevention valves that open and close using the pressure difference between the molten resin before and after the valve have the advantage of simplified structure. Therefore, backflow prevention valves that open and close using pressure difference can be installed not only between the screw and plunger of a pre-plasticized injection molding machine, but also at different locations in the molten resin flow path of the injection molding machine, depending on their purpose.

[0005] In the backflow prevention valves described in Japanese Patent Application Publication Nos. 2004-255588 and 2004-330672, during the opening operation, due to the pressure difference of the molten resin applied in the downstream direction, the valve body moves within the valve and abuts against a stop member, which has a structure that ensures the flow path remains open even when the valve body abuts against it. Furthermore, during the closing operation, the valve body moves within the valve due to the pressure difference of the molten resin applied in the upstream direction and comes into pressure contact with the valve seat, and the flow path is closed through the tight contact between the valve body and the valve seat.

[0006] In conventional backflow prevention valves, the valve body and seat, or the valve body and stop, repeatedly press and separate during the operation of the injection molding machine, causing wear on these parts. In particular, during the closing operation, the pressure difference between the molten resin before and after the valve acts directly on the contact area between the valve body and seat, making this area prone to wear. When the valve seat is damaged, the flow path of the molten resin cannot be completely closed, and the backflow prevention function deteriorates. Therefore, to ensure the long-term stable operation of the injection molding machine, it is necessary to improve the durability of the backflow prevention valve.

[0007] Furthermore, although not studied in Japanese Patent Application Publication Nos. 2004-255588A and 2004-330672A, when the backflow prevention valve wears down, it is necessary to remove the worn backflow prevention valve from the injection molding machine and reinstall a new or repaired one. Assuming such a replacement is to be performed, a method is needed that allows for easy attachment and removal of the backflow prevention valve and a high-adhesion installation of it into the flow path, preventing leakage of molten resin from the installation point. Summary of the Invention

[0008] According to a first aspect of the invention, the device includes: a first flow path component configured to define a first section of a flow path; a second flow path component configured to define a second section of a flow path; a valve unit configured to suppress backflow in the flow path; and a fastening member configured to secure the first and second flow path components. With the first and second flow path components secured by the fastening member, the valve unit is clamped between the first and second flow path components, and the first and second sections are connected via the valve unit. With the first and second flow path components released from their fastening, the valve unit can be detached from the first and second flow path components.

[0009] According to a second aspect of the invention, the device includes: a first flow path component configured to define a first section of a flow path; a second flow path component configured to define a second section of a flow path; and a valve unit configured to suppress backflow in the flow path. The first section and the second section are connected via the valve unit. The valve unit includes a first valve seat portion and a movable valve body, the first valve seat portion and the movable valve body being configured to close the flow path when the movable valve body abuts against the first valve seat portion. The first valve seat portion is configured to abut against the first flow path component and is made of a material with a higher hardness than the material constituting the first flow path component.

[0010] According to a third aspect of the invention, a valve unit is configured to suppress backflow in a flow path. The valve unit includes: a movable valve body; and a first valve seat portion configured to close the flow path when the movable valve body abuts against the first valve seat portion. The first valve seat portion is formed of a material with a hardness (Rockwell hardness) greater than or equal to HRC50 and less than HRC80.

[0011] Further features of the invention will become apparent from the following description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0012] Figure 1 This is a schematic cross-sectional view showing the state in which the backflow prevention valve 5 according to the first embodiment is installed in the flow path of the molten resin.

[0013] Figure 2 This is a schematic cross-sectional view showing the state of the backflow prevention valve 5 before it is incorporated into the flow path of the molten resin according to the first embodiment.

[0014] Figure 3A This is a schematic cross-sectional view of the backflow prevention valve 5 according to the first embodiment.

[0015] Figure 3B It is along Figure 3A The A-A' plane shown is a schematic perspective view of the segment at the inflow side, including the outlet 38, where the backflow prevention valve 5 is cut in half.

[0016] Figure 4A It is a schematic cross-sectional view showing the state of molten resin flowing in the downstream direction.

[0017] Figure 4B It is a schematic perspective view showing the state of molten resin flowing in the downstream direction.

[0018] Figure 5A This is a schematic cross-sectional view of the backflow prevention valve 5 according to the first embodiment.

[0019] Figure 5B It is along Figure 5AThe B-B' plane shown is a schematic perspective view of the segment at the side including the inlet 37, where the backflow prevention valve 5 is cut in half and viewed from the outflow side.

[0020] Figure 6A It is a schematic cross-sectional view showing the state in which molten resin is about to flow in the countercurrent direction.

[0021] Figure 6B It is a schematic perspective view showing the state in which molten resin is about to flow in the countercurrent direction.

[0022] Figure 7 This is a schematic cross-sectional view showing the forces applied to each part when the backflow prevention valve 5 is closed.

[0023] Figure 8 This is a schematic cross-sectional view showing the state of the pre-plasticized injection molding machine 80 performing the metering step according to the second embodiment.

[0024] Figure 9 This is a schematic cross-sectional view showing the state of the pre-plasticized injection molding machine 80 performing the injection step and the pressure holding step according to the second embodiment.

[0025] Figure 10 This is a schematic cross-sectional view showing the state of the multi-cavity molding apparatus 100 performing the injection step according to the third embodiment.

[0026] Figure 11 This is a schematic cross-sectional view showing the state in which the multi-cavity molding apparatus 100 according to the third embodiment performs the pressure holding step.

[0027] Figure 12 This is a schematic cross-sectional view showing the state of the multi-cavity molding apparatus 100 performing a metering step according to the third embodiment.

[0028] Figure 13A This is a schematic cross-sectional view showing the state in which the backflow prevention valve 50 according to the fourth embodiment is installed in the flow path of the molten resin.

[0029] Figure 13B This is a schematic cross-sectional view showing the state in which the backflow prevention valve 51 according to the fifth embodiment is installed in the flow path of the molten resin.

[0030] Figure 14 This is a schematic cross-sectional view showing the state in which the backflow prevention valve 52 according to the sixth embodiment is installed in the flow path of the molten resin.

[0031] Figure 15 This is a schematic cross-sectional view showing the state in which the backflow prevention valve 53 according to the seventh embodiment is installed in the flow path of the molten resin.

[0032] Figure 16This is a schematic cross-sectional view of a pre-plasticized injection molding machine according to the eighth embodiment.

[0033] Figure 17 This is a schematic cross-sectional view of the multi-cavity molding apparatus according to the ninth embodiment. Detailed Implementation

[0034] The following description of the embodiments of the present invention, including a molten resin flow path with a backflow prevention valve, an injection molding machine, etc., will be described with reference to the accompanying drawings. In the drawings referred to in the following description of the embodiments, unless otherwise stated, elements indicated by the same reference numerals have the same function.

[0035] First Embodiment

[0036] The following will describe a backflow prevention valve according to the first embodiment, a method for installing a backflow prevention valve in the flow path of molten resin, etc. Figure 1 This is a schematic cross-sectional view showing the state in which the backflow prevention valve 5 according to the first embodiment is installed in the flow path of the molten resin. Figure 2 This is a schematic cross-sectional view showing the state of the backflow prevention valve 5 before it is incorporated into the flow path of the molten resin. Figure 1 In the diagram, the forward and reverse flow directions of the molten resin are indicated by arrows, and the inflow and outflow sides of the molten resin into the flow path are indicated with reference to the forward flow direction. The backflow prevention valve 5, used as a valve unit, includes a valve body 10, a first valve seat portion 9, a second valve seat portion 11, and a housing 8. The operation of each part of the backflow prevention valve 5 will be described later.

[0037] A backflow prevention valve 5 is clamped between the first flow path component 1 and the second flow path component 2 in the left-right direction shown in the figure. The first flow path component 1 and the second flow path component 2 are fixed at the flange portion by bolts 6 as fastening components. In the first flow path component 1, the first flow path section 1C is defined as part of the molten resin flow path, and in the second flow path component 2, the second flow path section 2C is defined as part of the molten resin flow path. The first flow path section 1C and the second flow path section 2C are connected via the backflow prevention valve 5 to form a series of flow paths 3 through which the molten resin flows.

[0038] like Figure 2As shown, the first flow path component 1 has a recess with a depth L1 relative to the flange surface 1F when viewed along the flow path axial direction. The second flow path component 2 has a recess with a depth L2 relative to the flange surface 2F when viewed along the flow path axial direction. The end face (bottom face) of the recess of the first flow path component 1 is defined as 1T, and the end face (bottom face) of the recess of the second flow path component 2 is defined as 2T. In the backflow prevention valve 5, when the end face on the side of the first flow path component 1 is defined as 5R and the end face on the side of the second flow path component 2 is defined as 5L, the distance between 5L and 5R is set as LB. That is, the length of the backflow prevention valve 5 when viewed along the flow path axial direction is LB.

[0039] In this embodiment, the dimensions of each part are limited to satisfy the following expression (1).

[0040] L1+L2 <LB...(1)

[0041] exist Figure 1 In the assembled state shown, the end face 1T of the first flow path component 1 and the end face 5R of the backflow prevention valve 5 abut against each other, and the end face 2T of the second flow path component 2 and the end face 5L of the backflow prevention valve 5 abut against each other. Meanwhile, since the first flow path component 1 and the second flow path component 2 have a dimensional relationship defined by expression (1), the first flow path component 1 and the second flow path component 2 can be securely fixed by bolts 6. Since the housing 8 of the first flow path component 1, the second flow path component 2, and the backflow prevention valve 5 can be considered substantially rigid, the distance TM used as the fastening allowance is substantially equal to LB - (L1 + L2). Specifically, the distance TM used as the fastening allowance is preferably set in the range of greater than or equal to 2 μm and less than or equal to 100 μm, and particularly preferably set in the range of greater than or equal to 7 μm and less than or equal to 50 μm. This is to enable reliable fastening with a strong fastening force and to prevent the bolts from being crushed when external force is applied between the first flow path component 1 and the second flow path component 2.

[0042] According to this embodiment, since the distance TM used as a fastening allowance is ensured by the dimensional relationship defined in expression (1), the first flow path component 1 and the second flow path component 2 of the backflow prevention valve 5 can be fixed with sufficient force using bolt 6. Therefore, by applying sufficient pressure, end face 1T and end face 5R, and end face 2T and end face 5L can be brought into close contact with each other, and leakage of molten resin from the interface between the backflow prevention valve 5 and the first flow path component 1 and the interface between the backflow prevention valve 5 and the second flow path component 2 can be prevented.

[0043] According to this embodiment, since a sufficient seal can be achieved without joining the flow path components and the backflow prevention valve by brazing or the like, the installation of the backflow prevention valve is very easy. Furthermore, even when replacing the backflow prevention valve, it can be easily removed from the flow path components by removing the fastening parts (bolts). Figure 2 (As shown), this greatly reduces the load required to maintain the injection molding machine.

[0044] As long as expression (1) is satisfied, the depth L1 of the recess in the first flow path component 1 and the depth L2 of the recess in the second flow path component 2 can be set to any size. For example, the recess can be provided only in one of the first flow path component 1 and the second flow path component 2, while the other can have a depth of 0 (i.e., a flat surface).

[0045] Next, the backflow prevention valve 5, which serves as a valve unit, will be described in detail. For example... Figure 1 As shown, the backflow prevention valve 5 includes a valve body 10, a first valve seat portion 9, a second valve seat portion 11, and a housing 8.

[0046] Figure 3A This is a schematic cross-sectional view of the backflow prevention valve 5, but for ease of description, the valve body 10 is omitted. The molten resin flow path connecting the inlet 37 and outlet 38 is formed inside the backflow prevention valve 5, and... Figure 1 The spherical valve body 10 shown is accommodated in the flow path in a displaceable (movable) manner. Since the diameter of the spherical valve body 10 is larger than both the inlet 37 and the outlet 38, the valve body 10 can be located anywhere in the valve cavity 7 without deviating from the interior of the backflow prevention valve 5.

[0047] A recess is provided on the inflow side of the housing 8, and a first valve seat portion 9 is fitted into this recess. The bottom surface of the recess and the distal surface of the first valve seat portion 9 contact each other at the boundary portion 14. In this embodiment, the cross-sectional area of ​​the flow path of the molten resin in the backflow prevention valve 5 is maximized at the boundary portion 14 (where the bottom surface of the recess of the housing 8 and the distal surface of the first valve seat portion 9 abut each other). This is because high-pressure molten resin is unlikely to leak from the boundary portion. However, depending on the pressure of the molten resin in the valve chamber 7, the boundary portion 14 can be separated from the position where the cross-sectional area of ​​the flow path is maximized.

[0048] First, the situation regarding the opening of the backflow prevention valve 5 when the molten resin is about to flow in the downstream direction will be described. Figure 3B It is along Figure 3AThe A-A' plane shown is a schematic perspective view of a segment at the outlet 38 of the housing 8, viewed from the inflow side, cutting the backflow prevention valve 5 in half. A second valve seat portion 11, used to hold the valve body 10 in the flow path without closing it when the molten resin flows in the downstream direction, is provided on the outflow side of the flow path. The second valve seat portion 11 includes four protrusions (stops) distributed in the outer circumferential direction of the flow path, and the valve body 10 presses against these protrusions by the flow pressure when the molten resin flows in the downstream direction.

[0049] To describe this state, Figure 4A This is a schematic cross-sectional view of the backflow prevention valve 5. Figure 4B It is similar to Figure 3B A schematic perspective view, virtually cut across. The spherical valve body 10 receives force F through the flow pressure in the downstream direction. V It abuts against the inclined surface of the protrusion of the second valve seat portion 11, and a gap 36 is ensured between the protrusions for the molten resin to pass through. Therefore, the molten resin can flow out from the outlet 38, and backflow prevention valve 5 remains open relative to the flow in the downstream direction.

[0050] The ridge of the protrusion in the second valve seat portion 11 slopes axially from the inflow side toward the outflow side near the center of the flow path axis, and has a shape such that when the protrusion is viewed in a plan view along the flow path axis from the inflow side, there is no undercut portion that becomes a shadow. As a result, the molten resin flowing in the downstream direction does not remain near the protrusion, and resin degradation due to retention is suppressed.

[0051] Next, we will describe the situation where the backflow prevention valve 5 closes when the molten resin is about to flow in the counterflow direction. Figure 5A This is a schematic cross-sectional view of the backflow prevention valve 5, but for ease of description, the valve body 10 is omitted. Figure 5B It is along Figure 5A The diagram shows a schematic perspective view of the B-B' plane, which cuts the backflow prevention valve 5 in half and is viewed from the outflow side, including a segment at the inlet 37. The B-B' plane is the surface passing through the boundary portion 14, where the bottom surface of the recess of the housing 8 and the distal end face of the first valve seat portion 9 abut each other, and the flow path has the largest cross-sectional area at this location. The first valve seat portion 9 is a cylindrical component, but a tapered surface-shaped portion 13, with a diameter decreasing from the outflow side to the inflow side, exists on the inner surface of the cylindrical body. When the molten resin is about to flow in the counterflow direction, the spherical valve body 10 is pressed against the tapered surface-shaped portion 13 on the inner surface of the first valve seat portion 9 by the flow pressure.

[0052] To describe this state, Figure 6A This is a schematic cross-sectional view of the backflow prevention valve 5. Figure 6B It is similar to Figure 5B A schematic perspective view, virtually cut across. The spherical valve body 10 receives force F through the flow pressure in the counter-flow direction. M It abuts against the tapered surface portion 13 of the first valve seat portion 9, and there is no gap between the valve body 10 and the first valve seat portion 9 through which the molten resin can flow. Therefore, the molten resin cannot flow back and out of the inlet 37, and the backflow prevention valve 5 is closed relative to the flow in the reverse direction, thus the flow path of the molten resin can be closed.

[0053] Although the open and closed states of the backflow prevention valve 5 have been described above, the construction of each part of the backflow prevention valve 5 will be described in more detail. When the backflow prevention valve 5 is installed on an injection molding machine or similar device and the flow path is repeatedly opened / closed, the valve body 10 repeatedly presses against the protrusion of the second valve seat portion 11 and the first valve seat portion 9. When the molten resin flows in the forward direction and the valve is in the open state, the pressure on the valve body 10 against the protrusion of the second valve seat portion 11 is not very high because the gap 36 ensures that the molten resin can pass through. At the same time, when the molten resin is about to flow in the reverse direction and the valve is closed, the flow path is closed, so a large flow pressure is applied to the valve body 10, and the first valve seat portion 9 receives a strong force from the valve body 10.

[0054] In this embodiment, to improve the durability of the first valve seat portion 9, the first valve seat portion 9 is formed using a material with a higher hardness than the first flow path component 1, and the first valve seat portion 9 is mounted on the housing 8. The second valve seat portion 11, which includes a protrusion with a complex shape but relatively small pressure on the valve body, is integrally formed with the housing 8 using a material with excellent machinability. Meanwhile, the first valve seat portion 9, which requires higher durability, is formed using a material with a higher hardness than the material used for the first flow path component 1, and is mounted on the housing 8.

[0055] The outer peripheral surface of the cylindrical first valve seat portion 9 has a cylindrical shape and is fitted into a recess provided in the housing 8. As an assembly method, a shrink-fit with high adhesion strength is preferred from the viewpoint of suppressing resin leakage. In some cases, other assembly methods, such as light-pressure assembly, can be used. The inflow-side end face 15 of the first valve seat portion 9 is flush with or slightly protrudes towards the inflow side of the housing 8. This is because when the first flow path component 1 and the second flow path component 2 are fixed with bolts 6, the first valve seat portion 9 and the first flow path component 1 are in firm and tight contact with each other to prevent molten resin leakage.

[0056] Next, we will refer to Figure 7 The forces applied to each part when the backflow prevention valve 5 is closed are described in more detail. Figure 7 This is a schematic cross-sectional view showing the state where pressure is applied in the counter-flow direction and backflow prevention valve 5 is closed.

[0057] Because the first valve seat portion 9 is pushed against the flow direction by the valve body 10 and high pressure is applied in the valve cavity 7, a force F is generated at the boundary portion 14 between the housing 8 and the first valve seat portion 9 to create a gap. V Due to this force, a small gap may be created at the end of the boundary portion 14, and molten resin may seep in. However, since the first valve seat portion 9 is securely fitted to the housing 8 via a shrink fit or the like, the molten resin will not leak between the cylindrical outer surface of the first valve seat portion 9 and the recessed inner surface of the housing 8. That is, the molten resin will not enter the contact surface between the backflow prevention valve 5 and the first flow path component 1, and the molten resin will not leak to the outside.

[0058] In the closed state, because the valve body 10 is pressed against the first valve seat portion 9, the entire valve unit of the backflow prevention valve 5 is affected by force F. M The force presses against the inflow side. This force acts in the direction that separates the outflow side end face 16 of the backflow prevention valve 5 from the end face of the second flow path component 2. However, as already referred to Figure 1 As described above, since this embodiment is configured with a dimensional relationship that provides a distance TM for fastening, the first flow path component 1 and the second flow path component 2 are securely fixed by bolts 6. As a result, molten resin is prevented from leaking to the outside from the contact portion between the backflow prevention valve 5 and the second flow path component 2.

[0059] Although the open and closed states have been described above, the materials that make up the various parts will be further explained. For the first flow path component 1 and the second flow path component 2, materials with a hardness (Rockwell hardness) greater than or equal to HRC20 and less than HRC50 (e.g., SUS-based steel) are suitable from the perspective of balancing manufacturability during manufacturing and durability during use.

[0060] For the housing 8 of the backflow prevention valve, materials such as alloy tool steel (SKD11, die steel) with a hardness (Rockwell hardness) of HRC62, high-speed steel (SKH51, high-speed steel) with a hardness of HRC63, or SUS material with a hardness of HRC50 to HRC55 are suitable. This is because a balance is taken into account between machinability when forming the recess for receiving the first valve seat portion 9 and the protrusion for the second valve seat portion 11, and durability during use.

[0061] For the first valve seat portion 9, a material with a hardness (Rockwell hardness) greater than or equal to HRC50 and less than HRC80 is suitable. To improve durability during use, a material with a hardness higher than the first flow path component 1 but not so high as to make machining excessively difficult is selected. Specifically, alloy tool steel (SKD11, die steel) with a hardness (Rockwell hardness) of HRC62, high-speed steel (SKH51, high-speed steel) with a hardness of HRC63, or SUS-based materials with a hardness of HRC50 to HRC55 are suitable. For the valve body 10, from a durability perspective, for example, a cemented carbide (sintered carbide) with a hardness (Rockwell hardness) of HRC78 is suitable.

[0062] Furthermore, when the molten resin actually flows, every part of the equipment is at a high temperature. In this situation, to prevent reduced sealing of the flow path due to differences in thermal expansion, the first flow path component 1, the second flow path component 2, the housing 8, and the first valve seat portion 9 all utilize materials with a linear expansion coefficient of 9 × 10⁻⁶. -6 / K or higher and 13×10 -6 The material is formed in the range of / K or less. In particular, in order to ensure adhesion between the abutting portion of the first flow path component 1 and the first valve seat portion 9, it is preferable that the coefficient of linear expansion of the material constituting the first valve seat portion 9 is greater than the coefficient of linear expansion of the material constituting the first flow path component 1 within the above range.

[0063] Examples of preferred combinations of materials forming each part are shown below.

[0064] The first flow path component 1 and the second flow path component 2 are formed of SUS-based steel material (e.g., HPM77 manufactured by Hitachi Metals Ltd.), which has a hardness greater than or equal to HRC29 and less than or equal to HRC33, and a hardness greater than or equal to 10.1 × 10⁻⁶. -6 / K and less than or equal to 11.5 × 10 -6 The coefficient of linear expansion is / K. The backflow prevention valve housing 8 is formed of SUS-based material with a hardness of HRC50 to HRC55. The first valve seat portion 9 is made of material with a hardness of HRC63 and a coefficient of linear expansion of 11.9 × 10⁻⁶. -6 The valve body 10 is formed of high-speed steel (SKH51, high-speed steel) with a hardness of HRC78.

[0065] According to the above embodiment, since the first valve seat portion 9, which is in strong contact with the valve body 10 when preventing backflow, is formed of a material with a hardness higher than that of the first flow path component, the durability of the backflow prevention valve 5 is improved, and the backflow prevention valve 5 can operate stably for a long time.

[0066] Furthermore, with the first flow path component 1 and the second flow path component 2 clamping the backflow prevention valve 5, the first flow path component 1 and the second flow path component 2 are securely fixed together by bolts 6, and the first flow path component 1 and the second flow path component 2 are separated from each other due to the tightening allowance of the bolts 6. Utilizing a structure capable of applying a strong tightening force, the first flow path component 1 and the backflow prevention valve 5, as well as the second flow path component 2 and the backflow prevention valve 5, are in strong and tight contact (abutting) with each other, thus preventing molten resin from leaking through the gaps.

[0067] According to this embodiment, since a sufficient seal can be achieved without joining the flow path components and the backflow prevention valve by means of brazing or other methods, the installation of the backflow prevention valve is very easy. Furthermore, when replacing the backflow prevention valve, it can be easily removed from the flow path components by disassembling and releasing the fastening parts (bolts), significantly reducing the load required for maintaining the injection molding machine.

[0068] Second Embodiment

[0069] As a second embodiment, the construction and operation of a pre-plasticized injection molding machine equipped with the backflow prevention valve described in the first embodiment will be described. Figure 8 and Figure 9 This is a schematic cross-sectional view of a pre-plasticized injection molding machine equipped with a backflow prevention valve. Figure 8 The image shows the state of the pre-plasticized injection molding machine 80 performing the metering steps described later. Figure 9 The diagram shows the state of the pre-plasticized injection molding machine 80 performing the injection and pressure holding steps described later. In the description of the backflow prevention valve 5 shown in the accompanying drawings, portions identical to those in the first embodiment will be omitted or simplified.

[0070] Structure of a pre-plasticizing molding machine

[0071] The pre-plasticized injection molding machine 80 includes a molten resin supply unit 81, an injection unit 82, and a mold cavity 20. The molten resin supply unit 81 supplies molten resin, and the injection unit 82 injects the molten resin. The molten resin supply unit 81 includes a heater (not shown) for melting resin granules as molding material, and a screw 17 (e.g., φ35 mm) for ejecting molten resin toward the injection unit 82. The injection unit 82 includes a sleeve 18 for storing molten resin supplied from the molten resin supply unit 81, a plunger 21 (e.g., φ20 mm) capable of advancing or retracting within the sleeve 18, a switching valve 24, and a nozzle 19. The tip of the nozzle 19 is connected to a gate in the mold cavity 20, serving as the injection port for the molten resin. The switching valve 24 is capable of opening and closing the hot runner path connecting the sleeve 18 and the nozzle 19. A heater (not shown) for maintaining the molten resin at an appropriate temperature (e.g., 230°C) is attached to the molten resin supply unit 81 and the injection unit 82.

[0072] The molten resin supply unit 81 and the injection unit 82 are connected via a connecting unit 22. The connecting unit 22 includes a first flow path component 1 defining a first section (e.g., φ8 mm) of the flow path, a backflow prevention valve 5 as described in the first embodiment, and a second flow path component 2 defining a second section (e.g., φ8 mm) of the flow path. Furthermore, the first flow path component 1 is provided with a pressure sensor 23 for measuring the resin pressure in the flow path. Both the first and second flow path components 1 and 2 are made of SUS material and are equipped with heaters (not shown) to maintain the molten resin in the flow path at an appropriate temperature (e.g., 230°C).

[0073] refer to Figure 1 and 2 The dimensions described are L1+L2=20mm, LB=20.03mm. With TM=0.03mm set as the tightening allowance, the flange portions of the first flow path component 1 and the second flow path component 2 are secured with 12 bolts 6 (e.g., M12).

[0074] The housing 8 of the backflow prevention valve 5 (e.g., cylindrical outer diameter φ30mm) is made of SUS material, and the flow path diameter at the point of maximum cross-sectional area is set to φ14mm. The first valve seat portion 9 is made of high-speed steel with a higher hardness than the SUS material of the first flow path component 1, and has an outer circumferential diameter of 18mm. The first valve seat portion 9 is fitted to the housing 8 by a shrink fit. A spherical valve body 10 (e.g., φ10mm) made of hard alloy (sintered carbide) is inserted into the valve cavity defined by the housing 8 and the first valve seat portion 9.

[0075] Molding process

[0076] Next, the molding process using a pre-plasticized injection molding machine 80 will be described. First, as... Figure 8 As shown, a metering step is performed, wherein the switching valve 24 of the injection unit 82 is closed, the plunger 21 moves a predetermined distance in the upward direction as shown in the figure, and a predetermined amount of molten resin is metered and introduced into the sleeve 18. The raw material molten in the molten resin supply unit 81 is extruded from the molten resin supply unit 81 through the screw 17 rotating at 100 rpm. In this case, as referenced... Figure 4A and Figure 4B As described above, a flow in the downstream direction is generated in the backflow prevention valve 5 to open the backflow prevention valve 5. The molten resin that has passed through the backflow prevention valve 5 is metered by the movement distance of the plunger 21 and stored in the sleeve 18. In this case, a back pressure of 10 MPa is applied to the plunger 21. When the plunger 21 retracts back to the metering set value = 100 mm, the metering step is completed.

[0077] Next, we will refer to Figure 9The injection step and subsequent pressure holding step are described. When the amount of molten resin required to mold the resin-molded product in the above metering step is stored in the sleeve 18, the pre-plasticized injection molding machine 80 performs the injection step of injecting molten resin into the mold cavity 20.

[0078] During the injection procedure, such as Figure 9 As shown, the switching valve 24 opens to allow the sleeve 18 and nozzle 19 to communicate with each other, and the plunger 21 is advanced into the nozzle 19 at 100 mm / s to fill the mold cavity 20 with molten resin. In this case, a resin pressure of 200 MPa is applied to the valve chamber 7 of the backflow prevention valve 5, and this resin pressure acts in the counter-current direction relative to the backflow prevention valve 5, as shown in the reference. Figure 6A and 6B Therefore, the backflow prevention valve 5 is closed, preventing molten resin from flowing back into the molten resin supply unit 81.

[0079] When the mold cavity 20 is filled with molten resin, a pressure holding step is performed, in which pressure is applied until the resin at the gate portion solidifies (gate seal) to prevent the molten resin filling the mold cavity 20 from flowing back from the gate, causing the molded product to sink or shrink. During the pressure holding step, the plunger 21 operates in a pressure control mode that controls pressure rather than position. A pressure of 50 MPa is applied for 3 seconds during the pressure holding step. Furthermore, during the pressure holding step, for the backflow prevention valve 5, the pressure on the outflow side is greater than the pressure on the inflow side, thus the pressure difference acts in the counter-current direction. Therefore, the backflow prevention valve 5 remains closed, preventing molten resin from flowing back into the molten resin supply unit 81.

[0080] When the molten resin filling the mold cavity 20 solidifies, the mold is opened, and the resin-molded product is removed. Simultaneously, the metering step for the next injection molding begins, and the backflow prevention valve 5 is reopened.

[0081] Through the injection and pressure holding steps, a high pressure of up to 200 MPa is applied to the backflow prevention valve 5, which is in the closed state. However, even if injection molding is repeated multiple times, no resin leakage will occur in the connection unit 22 of the pre-plasticized injection molding machine 80 of this embodiment, where the backflow prevention valve has excellent durability.

[0082] In this embodiment, pressure sensor 23 can be used to confirm whether the backflow prevention valve 5 is normally open or normally closed. During the injection and pressure holding steps, when the backflow prevention valve 5 is properly closed, the high pressure state on the outflow side (plunger side) will not propagate to the first section of the flow path. When pressure sensor 23 detects an abnormal pressure increase, it can be inferred that a malfunction has occurred in the backflow prevention valve 5. In this case, in the pre-plasticized injection molding machine 80 of this embodiment, the backflow prevention valve can be easily removed from the flow path components by disassembling the fastening parts (bolts), and the backflow prevention valve can be easily replaced. As described above, the load required for maintaining the injection molding machine can be suppressed.

[0083] Third Embodiment

[0084] As a third embodiment, the construction and operation of a multi-cavity molding apparatus equipped with the backflow prevention valve described in the first embodiment will be described. This multi-cavity molding apparatus is an injection molding apparatus and includes manufacturing units, such as multi-part molds with different shapes. The injection molding machine used in the multi-cavity molding apparatus of this embodiment is an in-line screw type and is capable of performing the plasticizing, injection, and metering of the molding material by rotating, advancing, and retracting the screw, as described later.

[0085] Figures 10 to 12 This is a schematic cross-sectional view of a multi-cavity forming device 100 equipped with a backflow prevention valve 5. Figure 10 The image shows the state of the multi-cavity molding apparatus 100 performing the injection step described later. Figure 11 The image shows the state in which the multi-cavity molding apparatus 100 performs the pressure holding step described later. Figure 12 The diagram shows the state in which the multi-cavity molding apparatus 100 performs the metering steps described later. In the description of the backflow prevention valve 5 shown in the accompanying drawings, portions identical to those in the first embodiment will be omitted or simplified.

[0086] Structure of a multi-cavity molding device

[0087] The multi-cavity molding apparatus 100 includes a molten resin supply unit 30 and a manufacturing unit. The manufacturing unit includes a first cavity 25, a second cavity 26, a hot runner 27, a plunger 28, and a pressure control device 29 for driving the plunger 28. The first cavity 25 and the second cavity 26 are cavities for molding resin molded products with different shapes, and the internal volume of the first cavity 25 is larger than the internal volume of the second cavity 26. Molten resin is supplied from the molten resin supply unit 30 to the first cavity 25 and the second cavity 26 via the manifold-shaped hot runner 27. A first gate valve 31, which can be opened and closed, is located at the tip of the injection nozzle on the first cavity 25 side, and a second gate valve 32, which can be opened and closed, is located at the tip of the injection nozzle on the second cavity 26 side.

[0088] In the first embodiment, the backflow prevention valve 5 is installed in the hot runner 27 in a flow path branching from the molten resin supply unit 30 side to the first cavity 25 side, in the direction where the molten resin supply unit 30 is located on the inflow side. That is, the backflow prevention valve 5 is installed such that the direction from the molten resin supply unit 30 to the first cavity 25 is the downstream direction. The backflow prevention valve 5 is sandwiched between the first flow path component 1 and the second flow path component 2 constituting the hot runner 27, and as... Figure 1 As shown, the first flow path component 1 and the second flow path component 2 are fixed together by bolts. Furthermore, the first flow path component 1 is equipped with a pressure sensor 23 for measuring the resin pressure in the flow path. Both the first flow path component 1 and the second flow path component 2 are made of SUS material and are equipped with heaters (not shown) to maintain the molten resin in the flow path at a suitable temperature (e.g., 230°C).

[0089] refer to Figure 1 and 2 The dimensions described are L1+L2=35mm, LB=35.03mm. With TM=0.03mm set as the tightening allowance, the flange portions of the first flow path component 1 and the second flow path component 2 are secured with 12 bolts 6 (e.g., M12).

[0090] The housing 8 of the backflow prevention valve 5 (e.g., a cylindrical outer diameter of φ30mm) is made of SUS material, and the flow path diameter at the point of maximum flow path cross-sectional area is set to φ14mm. The first valve seat portion 9 is made of high-speed steel with a higher hardness than the SUS material of the first flow path component 1, and has an outer diameter of 18mm. The first valve seat portion 9 is fitted to the housing 8 by a shrink fit. A spherical valve body 10 (e.g., φ10mm) made of hard alloy (sintered carbide) is inserted into the valve cavity defined by the housing 8 and the first valve seat portion 9.

[0091] Molding process

[0092] Next, the molding process using the multi-cavity molding apparatus 100 will be described. In this embodiment, during the injection step, the first cavity 25 and the second cavity 26 are filled substantially simultaneously with molten resin from the molten resin supply unit 30. In the subsequent pressure holding step, different suitable pressures are applied to the first cavity 25 and the irregularly shaped second cavity 26, which are different from each other. That is, the holding pressure is applied from the plunger 28 driven by the pressure control device 29 to the first cavity 25, which has a large internal volume and a large suitable holding pressure. At the same time, the holding pressure is applied from the screw 33 of the molten resin supply unit 30 to the second cavity 26, which has a small internal volume and a small suitable holding pressure. During the pressure holding step, since the backflow prevention valve 5 is closed, a suitable pressure can be applied to each of the first cavity 25 and the second cavity 26 without causing molten resin backflow.

[0093] First, refer to Figure 10 A schematic cross-sectional view illustrates the injection process. In the injection process, firstly, with the second gate valve 32 connected to the second cavity closed, the first gate valve 31 connected to the first cavity 25 opens, and the screw 33 of the molten resin supply unit 30 advances at 50 mm / s. A predetermined amount of molten resin stored in the molten resin supply unit 30 is pushed into the flow path of the hot runner 27 by the advancing screw 33; however, because the second gate valve 32 is closed, the molten resin flows towards the first cavity 25. This flow is directed towards the backflow prevention valve 5 in the downstream direction (as shown in the reference). Figure 4A and Figure 4B Therefore, the backflow prevention valve 5 opens, and the first cavity 25 is filled with molten resin. The amount of resin filling the first cavity 25 can be determined by pre-checking the relationship between the advance amount of the screw 33 and the amount of molten resin supplied to the hot runner 27. For example, the internal volume of the first cavity is 60 cm³. 3 Furthermore, the internal volume of the second cavity is 30 cm³. 3 At that time, the second gate valve 32 is controlled so that the unfilled volume of the first cavity becomes 30 cm³. 3 The mold opens at the exact moment. Afterward, because molten resin is supplied to both cavities in parallel, filling can be completed almost simultaneously.

[0094] Next, we will refer to Figure 11 A schematic cross-sectional view illustrates the pressure holding step. In this step, pressure is maintained in the flow path of the hot runner 27 using a φ14 plunger 28 under the control of the pressure control device 29. Specifically, a holding pressure of 80 MPa is applied to the hot runner flow path for 3 seconds. Simultaneously, pressure is applied to the flow path of the hot runner 27 using the screw 33 of the molten resin supply unit 30. Specifically, a holding pressure of 50 MPa is applied to the flow path of the hot runner 27 for 3 seconds.

[0095] In this situation, for backflow prevention valve 5, since the outflow pressure is greater than the inflow pressure, the flow pressure difference acts in the counter-flow direction, as shown in the reference. Figure 6A and Figure 6B Therefore, the backflow prevention valve 5 is closed to prevent molten resin from flowing back into the molten resin supply unit 81. A holding pressure of 80 MPa applied from the plunger 28 is applied to the first cavity, and a holding pressure of 50 MPa applied from the screw 33 is applied to the second cavity 26. As described above, in this embodiment, since the backflow prevention valve 5 is closed, different holding pressures suitable for each cavity can be applied simultaneously. When the pressure holding step is completed, the first gate valve 31 and the second gate valve 32 are closed, and the metering step begins in preparation for the next injection molding.

[0096] Next, we will refer to Figure 12 A schematic cross-sectional view illustrates the metering step. In the metering step, the positions of the screw 33 and plunger 28 of the molten resin supply unit 30 are reset to the starting positions of the injection step, and a predetermined amount of molten resin required for the next injection step is stored in the molten resin supply unit 30. In this case, the screw 33 rotates at 100 rpm to apply a back pressure of 10 MPa, and the plunger 28 retracts at 50 mm / s. The outflow side pressure of the backflow prevention valve 5 is forcibly reduced to 0 MPa, while the inflow side pressure is 10 MPa. Therefore, as referenced... Figure 4A and Figure 4B As described above, a pressure differential is generated in the backflow prevention valve 5 along the downstream direction, causing the backflow prevention valve 5 to open and enabling the metering step to be performed without any problems. After the cooling time has passed and the resin in the cavity has cured, the mold is opened, and the corresponding resin-molded products are removed from the first cavity 25 and the second cavity 26. After removal and metering are completed, the process proceeds to the injection step again.

[0097] In this embodiment, a high pressure of 80 MPa is applied to the backflow prevention valve 5, which is in the closed state, through a pressure holding step. However, even when injection molding is repeatedly performed, in the multi-cavity molding apparatus 100 of this embodiment, no resin leakage occurs at the connection unit between the backflow prevention valve 5 and the flow path components (first flow path component 1 and second flow path component 2), and an appropriate holding pressure is maintained.

[0098] In this embodiment, pressure sensor 23 can be used to confirm whether the backflow prevention valve 5 is normally open or normally closed. During the pressure holding step, when the backflow prevention valve 5 is properly closed, the high pressure state on the outflow side (plunger side) will not propagate to the first section of the flow path. When pressure sensor 23 detects an abnormal pressure increase, it can be inferred that a malfunction has occurred in the backflow prevention valve 5. In this case, in the multi-cavity molding apparatus 100 of this embodiment, the backflow prevention valve can be easily removed from the flow path components by disassembling the fastening parts (bolts), and the backflow prevention valve can be easily replaced. In this way, the load required for maintaining the manufacturing unit can be suppressed.

[0099] Fourth embodiment

[0100] Reference Figure 13AA schematic cross-sectional view describes the check valve 50 according to the fourth embodiment, a method of installing the check valve in a flow path of molten resin, and the like. The check valve 50 of the present embodiment is structurally different from the check valve 5 of the first embodiment. In the check valve 5 of the first embodiment, the housing 8 is formed of, for example, SUS material and includes a second valve seat portion 11. The first valve seat portion 9 formed of a material (for example, high-speed steel) having a hardness higher than that of the material of the first flow path member 1 (for example, SUS material) is installed on the inflow side of the housing 8.

[0101] In the check valve of the fourth embodiment, the housing includes a housing member 34A on the inflow side and a housing member 34B on the outflow side. The housing is divided into the housing member 34A and the housing member 34B at a position where the cross-sectional area of the flow path in the valve chamber 7 is maximized, and the abutting surface between the housing member 34A and the housing member 34B is orthogonal to the axial direction of the flow path. However, depending on the pressure of the molten resin in the valve chamber 7, the dividing position may not coincide with the position where the cross-sectional area of the flow path is maximized. The first valve seat portion 9 (conical surface-shaped portion 13) is formed in the housing member 34A, and the second valve seat portion 11 (projection) is formed in the housing member 34B.

[0102] Assuming that the first flow path member 1 and the second flow path member 2 are made of, for example, SUS material, in the present embodiment, the housing member 34A and the housing member 34B are made of a material (for example, high-speed steel) having a hardness higher than that of the flow path members. The dimensional relationship of L1 + L2 < LB is the same as that in the first embodiment.

[0103] According to the present embodiment, the first valve seat portion 9 with which the valve body 10 comes into strong contact when preventing backflow is formed of a material having a hardness higher than that of the first flow path member. The second valve seat portion 11 with which the valve body 10 comes into contact during forward flow is formed of a material having a hardness higher than that of the second flow path member. Therefore, the durability of the check valve 50 is improved, and the check valve can operate stably for a long time.

[0104] In addition, in a state where the first flow path member 1 and the second flow path member 2 sandwich the check valve 50, the first flow path member 1 and the second flow path member 2 are firmly fixed by bolts 6, and the first flow path member 1 and the second flow path member 2 are separated from each other due to the tightening margin of the bolts 6. With a structure capable of applying a strong tightening force, the first flow path member 1 and the check valve 50, and the second flow path member 2 and the check valve 50 are in strong close contact (abutment) with each other, and leakage of molten resin from the gap is suppressed.

[0105] According to this embodiment, since a sufficient seal can be achieved without joining the flow path components and the backflow prevention valve by means of brazing or other methods, the installation of the backflow prevention valve is very easy. Furthermore, even when replacing the backflow prevention valve, the backflow prevention valve can be easily removed from the flow path components by removing the fastening parts (bolts), and the load required for maintaining manufacturing equipment such as injection molding machines or manufacturing units can be greatly reduced.

[0106] Fifth Embodiment

[0107] Reference Figure 13B The schematic cross-sectional view illustrates a modified backflow prevention valve 51 as a fourth embodiment. The fourth embodiment differs from this embodiment in the shape of the abutment surfaces of housing components 34A and 34B. In the fourth embodiment, the abutment surface between housing components 34A and 34B is a plane orthogonal to the axial direction of the flow path, but in this embodiment, the abutment surface has a stepped shape.

[0108] Before installing the backflow prevention valve on a manufacturing device (such as an injection molding machine or manufacturing unit), it is convenient to operate the housing component 34A, housing component 34B, and valve body 10 as a single valve unit, rather than operating them separately as individual parts. According to this embodiment, since the housing component 34A and housing component 34B can be assembled with each other in a stepped shape and can be assembled into a valve unit, operation is easy, and installation into the molten resin flow path of an injection machine, etc., is also convenient.

[0109] Sixth Embodiment

[0110] Reference Figure 14 The schematic cross-sectional view illustrates a modified backflow prevention valve 52 as a fourth embodiment. In both the fourth embodiment and this embodiment, the abutment surfaces of housing components 34A and 34B have the same shape; however, in this embodiment, through holes are provided in housing components 34A and 34B, and the housing components are fixed to each other by bolts 35 as fastening members.

[0111] Before installing the backflow prevention valve on a manufacturing device (e.g., an injection molding machine or manufacturing unit), it is convenient to operate the housing component 34A, housing component 34B, and valve body 10 as a single valve unit, rather than operating them separately as individual parts. According to this embodiment, since the housing component 34A and housing component 34B can be secured with bolts 35 and assembled into a valve unit, operation is convenient, and installation in the molten resin flow path of the injection machine, etc., is also easy.

[0112] Seventh Embodiment

[0113] Reference Figure 15 The schematic cross-sectional view illustrates a modified backflow prevention valve 53 according to the first embodiment. Similar to the backflow prevention valve 5 of the first embodiment, in this embodiment of the backflow prevention valve 53, the housing 8 is formed of, for example, SUS material, and the housing 8 includes a second valve seat portion 11. A first valve seat portion 9, formed of a material (e.g., high-speed steel) with a higher hardness than the material of the first flow path component 1 (e.g., SUS material), is fitted to the inflow side of the housing 8.

[0114] The difference from the first embodiment is that a through hole is provided in the housing 8, and the bolt 6, which serves as a fastening component, passes through the through hole and is fixed while the backflow prevention valve 53 is clamped between the first flow path component 1 and the second flow path component 2.

[0115] Similarly, in this embodiment, since the first valve seat portion 9, which is in strong contact with the valve body 10 when preventing backflow, is made of a material with a higher hardness than the first flow path component, the durability of the backflow prevention valve 5 is improved, and the backflow prevention valve 5 can operate stably for a long time.

[0116] Furthermore, according to this embodiment, since a sufficient seal can be achieved through fastening components without the need for joining flow path components and backflow prevention valve by means of brazing or other methods, the backflow prevention valve is easy to install. Moreover, even when replacing the backflow prevention valve, it can be easily removed from the flow path components by removing the fastening components (bolts), which can greatly reduce the load required for maintaining manufacturing equipment such as injection molding machines or manufacturing units.

[0117] Eighth embodiment

[0118] The detailed construction of the preplasticization injection device equipped with the backflow prevention valve described in the second embodiment will be described. Figure 16 This is a schematic cross-sectional view of a pre-plasticized injection molding machine equipped with a backflow prevention valve. Figure 16 The state of the pre-plasticized injection molding machine 80 performing the metering steps described later is shown. In the description of the backflow prevention valve 5 shown in the figures, the parts that are the same as those in the description of the first embodiment will be omitted or simplified.

[0119] Structure of a pre-plasticizing molding machine

[0120] The pre-plasticized injection molding machine 80 includes a molten resin supply unit 81, an injection unit 82, and a mold cavity 20. The molten resin supply unit 81 includes a heater (not shown) for melting resin granules as molding material, and a screw 17 (e.g., φ35 mm) for pushing the molten resin into the injection unit 82. The injection unit 82 includes a sleeve 18 for storing molten resin supplied from the molten resin supply unit 81, a plunger 21 (e.g., φ20 mm) capable of advancing or retracting within the sleeve 18, a switching valve 24, and a nozzle 19. The tip of the nozzle 19 is connected to a gate in the mold cavity 20, serving as the injection port for the molten resin. The switching valve 24 is capable of opening and closing the hot runner path connecting the sleeve 18 and the nozzle 19. A heater (not shown) for maintaining the molten resin at an appropriate temperature (e.g., 230°C) is attached to the molten resin supply unit 81 and the injection unit 82.

[0121] The connecting unit 22 includes a first flow path component 1 defining a first section (e.g., φ8 mm) of the flow path, a backflow prevention valve 5 as described in the first embodiment, and a second flow path component 2 defining a second section (e.g., φ8 mm) of the flow path. Furthermore, the first flow path component 1 is provided with a pressure sensor 23 for measuring the resin pressure in the flow path. Both the first and second flow path components 1 and 2 are made of SUS material and are equipped with heaters (not shown) to maintain the molten resin in the flow path at an appropriate temperature (e.g., 230°C).

[0122] The backflow prevention valve 5 is held by the connecting unit 22. The molten resin supply unit 81 is attached to the first flow path component 1 by bolts. The injection unit 82 is attached to the second flow path component 2 by bolts. In addition, the nozzle 19 has a threaded portion and is attached by being tightened into a threaded hole formed in the second flow path component 2.

[0123] When replacing the backflow prevention valve 5, the first flow path component 1 and the molten resin supply unit 81 are arranged in the direction of the first flow path component 1 and the molten resin supply unit 81. Figure 16 Separated in the vertical direction. Furthermore, the second flow path component 2 and the injection unit 82 are arranged in the direction (vertical direction). Figure 16 Separated in the vertical direction. In this way, the molten resin supply unit 81, injection unit 82, and nozzle 19 are removed from the first flow path component 1 and the second flow path component 2. Thereafter, the bolts connecting unit 22 are removed, and the first flow path component 1 and the second flow path component 2 are separated in the direction in which they are arranged (vertically). Figure 16 Separation occurs in the left-right direction within the flow path. As a result, the backflow prevention valve 5 can be removed between the first flow path component 1 and the second flow path component 2. (See reference...) Figure 1 and 2The dimensions described are L1+L2 = 20 mm and LB = 20.03 mm. With TM = 0.03 mm set as the tightening allowance, the flange portions of the first flow path component 1 and the second flow path component 2 are secured with 12 bolts 6 (e.g., M12).

[0124] The housing 8 of the backflow prevention valve 5 (e.g., cylindrical outer diameter φ30mm) is made of SUS material, and the flow path diameter at the point of maximum cross-sectional area is set to φ14mm. The first valve seat portion 9 is made of high-speed steel with a higher hardness than the SUS material of the first flow path component 1, and has an outer circumferential diameter of 18mm. The first valve seat portion 9 is fitted to the housing 8 by a shrink fit. A spherical valve body 10 (e.g., φ10mm) made of hard alloy (sintered carbide) is inserted into the valve cavity defined by the housing 8 and the first valve seat portion 9.

[0125] Assuming the molten resin supply unit 81 is referred to as the first component and the injection unit 82 as the second component, this embodiment has the following structural features: The first component is detachably connected to the first flow path component 1, and the second component is detachably connected to the second flow path component 2. The attachment / detachment directions of the first flow path component 1 and the first component are... Figure 16 The vertical direction in the middle) and the direction in which the first flow path component 1 and the second flow path component 2 are arranged ( Figure 16 (The left and right directions in the middle) intersect. The attachment / removal direction of the second flow path component 2 and the second component ( Figure 16 The vertical direction in the middle) and the direction in which the first flow path component 1 and the second flow path component 2 are arranged ( Figure 16 The left and right directions intersect. In this way, for example, there are advantages such as enabling device miniaturization, facilitating device assembly and disassembly (attachment and removal of components), and saving space required for assembling and disassembling the device. At least one of the attachment / removal directions of the first flow path component 1 and the first member, and the attachment / removal directions of the second flow path component 2 and the second member, can be the same as the direction in which the first flow path component 1 and the second flow path component 2 are arranged. However, when the four components—the first member, the first flow path component 1, the second flow path component 2, and the second member—are arranged in a line, the above advantages are diminished.

[0126] Ninth Embodiment

[0127] The detailed construction of a multi-cavity molding apparatus equipped with the backflow prevention valve described in the first embodiment will be described. This multi-cavity molding apparatus is an injection molding apparatus and includes, for example, a manufacturing unit for multi-part molds of different shapes. The injection molding machine used in the multi-cavity molding apparatus of this embodiment is an inline screw type, and the plasticizing, injection, and metering of the molding material can be performed by the rotation, advance, and retraction of the screw, as described later.

[0128] Figure 17 This is a schematic cross-sectional view of a multi-cavity forming device 100 equipped with a backflow prevention valve 5. Figure 17 The diagram shows the state in which the multi-cavity molding apparatus 100 performs the injection steps described later. In the description of the backflow prevention valve 5 shown in the accompanying drawings, portions identical to those in the first embodiment will be omitted or simplified.

[0129] Structure of a multi-cavity molding device

[0130] The multi-cavity molding apparatus 100 includes a molten resin supply unit 30 and a manufacturing unit. The manufacturing unit includes a first cavity 25, a second cavity 26, a hot runner 27, a plunger 28, and a pressure control device 29 for driving the plunger 28. The first cavity 25 and the second cavity 26 are cavities for molding resin molded products with different shapes, and the internal volume of the first cavity 25 is larger than the internal volume of the second cavity 26. Molten resin is supplied from the molten resin supply unit 30 to the first cavity 25 and the second cavity 26 via the manifold-type hot runner 27. An openable and closable first gating valve 31 is provided at the tip of the injection nozzle 101 on the first cavity 25 side, and an openable and closable second gating valve 32 is provided at the tip of the injection nozzle 102 on the second cavity 26 side.

[0131] In the first embodiment, the backflow prevention valve 5 is installed in the hot runner 27 in a flow path branching from the molten resin supply unit 30 side to the first cavity 25 side, with the molten resin supply unit 30 located on the inflow side. That is, the backflow prevention valve 5 is installed such that the direction from the molten resin supply unit 30 to the first cavity 25 is the downstream direction. The backflow prevention valve 5 is sandwiched between the first flow path component 1 and the second flow path component 2 constituting the hot runner 27, and as described above... Figure 1 As shown, the first flow path component 1 and the second flow path component 2 are fixed together by bolts. Furthermore, the first flow path component 1 is equipped with a pressure sensor 23 for measuring the resin pressure in the flow path.

[0132] The injection nozzle 101 and the second flow path component 2, installed between the second flow path component 2 and the first cavity 25, are formed as separate components and are not fixed. A heater (not shown) is arranged in the injection nozzle 101 and the second flow path component 2, and its temperature rises as the molten resin flows. The injection nozzle 101 thermally expands due to the increased temperature, thus the injection nozzle 101 and the second flow path component 2 are in firm contact with each other. As a result, no molten resin leakage occurs at the contact portion between the injection nozzle 101 and the second flow path component 2. The injection nozzle 102 and the first flow path component 1 also have the same construction as described above, and no resin leakage occurs at the contact portion between the injection nozzle 102 and the first flow path component 1. Furthermore, a hot runner gate 103 is installed between the first flow path component 1 and the molten resin supply unit 30.

[0133] The hot runner gate 103 and the first flow path component are secured by bolts (not shown). During molding, the molten resin supply unit 30 is pressed against the hot runner gate 103. Due to this pressing force, the contact portions between the molten resin supply unit 30 and the hot runner gate 103, and between the molten resin supply unit and the first flow path component 1, are firmly in contact with each other, thus preventing resin leakage. When replacing the backflow prevention valve 5, firstly, along the direction in which the mold components 104 and 105 are arranged ( Figure 17 Separate mold components 104 and 105 in the left-right direction, and remove the hot runner 27 assembly from the mold. Then, along the direction in which the injection nozzles 101 and 102, the hot runner gate 103, and the hot runner 27 are arranged (in the left-right direction). Figure 17 The injection nozzles 101 and 102, the hot runner gate 103, and the hot runner 27 are separated from each other in the left-right direction. As a result, the injection nozzles 101, 102, and 103 are removed from the hot runner 27. Thereafter, in the direction in which the first flow path component 1 and the second flow path component 2 are arranged (… Figure 17 In the vertical direction, remove the fastening bolts of the first flow path component 1 and the second flow path component 2 to separate the first flow path component 1 and the second flow path component 2. As a result, the backflow prevention valve 5 can be removed from between the first flow path component 1 and the second flow path component 2.

[0134] The first flow path component 1 and the second flow path component 2 are made of SUS material and are equipped with heaters (not shown) to maintain the molten resin in the flow path at a suitable temperature (e.g., 230°C). Reference Figure 1 and 2 The dimensions described are L1+L2 = 35 mm and LB = 35.03 mm. With TM = 0.03 mm set as a tightening allowance, the flange portions of the first flow path component 1 and the second flow path component 2 are secured with 12 bolts 6 (e.g., M12). The housing 8 of the backflow prevention valve 5 (e.g., cylindrical outer circumferential diameter φ30 mm) is made of SUS material, and the flow path diameter at the location maximizing the flow path cross-sectional area is set to φ14 mm. The first valve seat portion 9 is formed of high-speed steel with a higher hardness than the SUS material of the first flow path component 1, and has an outer circumferential diameter of 18 mm. The first valve seat portion 9 is assembled to the housing 8 via a shrink fit. A spherical valve body 10 (e.g., φ10 mm) made of hard alloy (sintered carbide) is inserted into the valve cavity defined by the housing 8 and the first valve seat portion 9.

[0135] Assuming mold component 104 or injection nozzle 101 is referred to as the first component and mold component 105, injection nozzle 102, or hot runner gate 103 is referred to as the second component, this embodiment has the following structural features. The first component is detachably connected to the first flow path component 1, and the second component is detachably connected to the second flow path component 2. The attachment / detachment direction of the first flow path component 1 and the first component ( Figure 17 The left and right directions in the middle) and the directions in which the first flow path component 1 and the second flow path component 2 are arranged ( Figure 17 The vertical direction intersects with the horizontal direction. The attachment / removal direction of the second flow path component 2 and the second component (…). Figure 17 The left and right directions in the middle) and the directions in which the first flow path component 1 and the second flow path component 2 are arranged ( Figure 17 The vertical direction (in the middle) intersects. In this way, for example, there are advantages such as enabling miniaturization of the device, facilitating the assembly and disassembly of the device (attachment and removal of components), and saving the space required for assembling and disassembling the device. At least one of the attachment / removal directions of the first flow path component 1 and the first member, and the attachment / removal directions of the second flow path component 2 and the second member, can be the same as the direction in which the first flow path component 1 and the second flow path component 2 are arranged. However, when the four components—the first member, the first flow path component 1, the second flow path component 2, and the second member—are arranged in a line, the above advantages are diminished.

[0136] Other embodiments

[0137] Note that the present invention is not limited to the above embodiments, and many modifications can be made within the scope of the technical concept of the present invention. For example, the valve body for the backflow prevention valve can be any component that can be shifted by flow pressure and can close the flow path by close contact with the first valve seat portion by flow pressure in the reverse flow direction, and the shape of the valve body is not limited to a spherical shape.

[0138] Furthermore, examples of installing a backflow prevention valve according to the first embodiment have been described in the pre-plasticized injection molding machine according to the second embodiment and the inline screw type multi-cavity molding apparatus according to the third embodiment, but backflow prevention valves according to the fourth to seventh embodiments may also be installed.

[0139] Furthermore, the target equipment for installing the backflow prevention valve according to the embodiments is not limited to preplasticized injection molding machines or inline screw-type multi-cavity molding devices; the backflow prevention valve can be installed on various devices having a molten resin flow path. For example, the backflow prevention valve can be installed on molding machines (e.g., plunger molding machines, preplasticized molding machines, plunger preplasticized molding machines, screw preplasticized molding machines, and screw molding machines).

[0140] A device that includes components defining a flow path can be referred to as a flow path device. Although molten resin has been described as a fluid flowing through the flow path, the fluid flowing through the flow path is not limited to molten resin. Furthermore, the target device (flow path device) for installing the backflow prevention valve according to the embodiment is not limited to a device that includes a molten resin flow path. Since it is sufficient for the valve body to be displaced by the pressure of the fluid flowing through the flow path of the target device, for example, a device that includes a molten metal flow path, a device that includes a flow path including water, which is liquid even at room temperature, or a device that includes a flow path including a gas such as compressed air can be used.

[0141] While the invention has been described with reference to exemplary embodiments, it should be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims should be given the broadest interpretation to cover all such modifications and equivalent structures and functions.

Claims

1. An apparatus comprising: A first flow path component, which is configured to define a first section of the flow path; The second flow path component is configured to define a second section of the flow path; A valve unit configured to suppress backflow in the flow path; and Fastening components, configured to secure the first flow path component and the second flow path component, With the first flow path component and the second flow path component fixed by the fastening component, the valve unit is clamped between the first flow path component and the second flow path component, and the first section and the second section are connected via the valve unit. With the first and second flow path components released from their fastening, the valve unit can be detached from both components. The first flow path component and the second flow path component are fixed to each other in a way that they are separated by the fastening allowance of the fastening component.

2. The apparatus according to claim 1, wherein, The fastening allowance of the fastening components is greater than or equal to 7μm and less than or equal to 50μm.

3. An apparatus comprising: A first flow path component, which is configured to define a first section of the flow path; The second flow path component is configured to define a second section of the flow path; and The valve unit is configured to suppress backflow in the flow path. The first section and the second section are connected by a valve unit. The valve unit includes a first valve seat portion and a movable valve body, the first valve seat portion and the movable valve body being configured to close the flow path when the movable valve body abuts against the first valve seat portion, and The first valve seat portion is configured to abut against the first flow path component and is made of a material with a higher hardness than the material constituting the first flow path component. The first flow path component and the second flow path component are fixed to each other in a way that they are separated by the fastening allowance of the fastening component.

4. The apparatus according to claim 3, wherein, The first valve seat portion is formed of a material with a hardness, i.e., a Rockwell hardness greater than or equal to HRC50 and less than HRC80, and The first flow path component is formed of a material with a hardness, i.e., a Rockwell hardness greater than or equal to HRC20 and less than HRC50.

5. The apparatus according to claim 3 or 4, wherein, The valve unit also includes a housing configured to abut against the first valve seat portion, and The movable valve body is housed in a valve cavity defined by the housing and the first valve seat portion.

6. The apparatus according to claim 5, wherein, The housing includes a second valve seat portion configured to not close the flow path when the movable valve body abuts against the second valve seat portion.

7. The apparatus according to claim 5, wherein, The housing and the first valve seat portion are configured to abut against each other at a location where the flow path cross-sectional area of ​​the valve cavity is maximized.

8. The apparatus according to claim 1 or 3, wherein, The first flow path component is equipped with a pressure sensor.

9. The apparatus according to claim 1 or 3, wherein, The flow path is the flow path of the molten resin.

10. The apparatus according to claim 1 or 3, further comprising: The first component is detachably connected to the first flow path component; and The second component is detachably connected to the second flow path component. The attachment / removal directions of the first flow path component and the first member, as well as the attachment / removal directions of the second flow path component and the second member, intersect with the directions in which the first flow path component and the second flow path component are arranged.

11. The apparatus according to claim 1, wherein, The fastening allowance is configured such that the first flow path component and the second flow path component do not contact each other and are separated by a gap from the valve unit to the fastening component.

12. A mold comprising the means according to any one of claims 1 to 11, in, A cavity is provided in the mold.

13. An injection molding machine, comprising: The apparatus according to any one of claims 1 to 11; A supply unit configured to supply molten resin; and An injection unit configured to inject molten resin. The first flow path component and the second flow path component are configured to connect the supply unit and the injection unit.

14. A method for manufacturing resin-molded products using an injection molding machine according to claim 13, the method comprising: Measurement steps; Injection procedure; and Pressure maintenance steps, The valve unit opens during the metering step, and The valve unit is closed during the injection and pressure holding steps.

15. A manufacturing unit, comprising: The apparatus according to claim 1 or 3; A supply unit configured to supply molten resin; First type cavity; and Second type cavity, The first flow path component and the second flow path component are disposed between the supply unit and the first cavity in a manifold connecting the supply unit, the first cavity and the second cavity.

16. A method for manufacturing a resin-molded product using the manufacturing unit according to claim 15, the method comprising: Measurement steps; Injection procedure; and Pressure maintenance steps, The valve unit opens during the metering and injection steps, and The valve unit closes during the pressure holding step.

17. A valve unit configured to suppress backflow in a flow path, the valve unit comprising: Displaceable valve body; and The first valve seat portion is configured to close the flow path when the movable valve body abuts against the first valve seat portion. The first valve seat portion is formed of a material with a hardness, specifically a Rockwell hardness greater than or equal to HRC50 and less than HRC80. The valve unit is sandwiched between a first flow path component and a second flow path component. The first flow path component is configured to define a first section of the flow path, and the second flow path component is configured to define a second section of the flow path. The first flow path component and the second flow path component are fixed to each other in a way that they are separated by the fastening allowance of the fastening component.

18. The valve unit of claim 17, further comprising a housing configured to abut against the first valve seat portion. in, The movable valve body is housed in a valve cavity defined by the housing and the first valve seat portion.

19. The valve unit according to claim 18, wherein, The shell is formed of mold steel, high-speed steel or SUS-based material with a hardness of HRC50 to HRC55.

20. The valve unit according to claim 18 or 19, wherein, The housing includes a second valve seat portion configured to not close the flow path when the movable valve body abuts against the second valve seat portion.

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