In-mold coating injection device

Abstract

To provide a compact in-mould coating dosing system with high accuracy of the amount of liquid coating material (e.g. paint) injected, and a high yield of liquid coating material.SOLUTION: In-mould coat injector 1 for injecting a predetermined amount of paint 6 into the coating gap 5 between the inner surface of the other mould 4 and the surface of the moulded base material 2, by pressing the other mould 4 over the moulded base material 2 against one mould 3 in which the moulded base material 2 is held, and using the metering cylinder 9 of the paint 6 as an extrusion cylinder, by doing so, the piping connecting the metering cylinder 9 and the extrusion cylinder is made unnecessary, the metering accuracy is improved by closing the inlet 8 with a dividing valve 14 when leading the paint 6 to the metering cylinder 9, and the equipment is made compact and the material yield of the paint 6 is improved by not using a circulation path and circulation pump for the paint 6.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an in-mold coating injection device that presses another mold against one mold holding a molding substrate so as to cover the molding substrate, and injects a predetermined amount of a liquid coating agent into a coating gap between the inner surface of the other mold and the surface of the molding substrate.

Background Art

[0002] In recent years, as the interest in environmental problems has increased, a mold-in coating method (in-mold coating: IMC) has attracted attention as a coating alternative technology that does not use organic solvents and has a high CO2 emission reduction effect. IMC is a technology in which another mold is pressed against one mold holding a molding substrate so as to cover the molding substrate, and a liquid coating agent (for example, a thermosetting paint) is injected into a coating gap between the inner surface of the other mold and the surface of the molding substrate, and a film is formed on the outer surface of the molding substrate by heating.

[0003] The characteristics of IMC include: (1) it is environmentally and user-friendly because it does not use organic solvents used in general spray coating; (2) equipment for performing the coating process (spraying, oven heat treatment) is unnecessary; (3) since the paint is not diluted with an organic solvent, the ratio (coating efficiency) at which the material (paint) before application is formed as a coating film on the outer surface of the molding substrate is very high and waste is extremely small, etc. IMC is used for the purpose of improving the quality of the surface of molded products and simplifying the coating process, and is widely used for exterior parts, etc. in the automotive industry where the requirements for appearance and quality are particularly high.

[0004] By the way, in IMC, another mold is pressed against one mold holding a molding substrate so as to cover the molding substrate, and in a state where a coating gap is formed between the inner surface of the other mold and the surface of the molding substrate, in order to inject a liquid coating agent into the coating gap, it is essential to inject an appropriate amount of the liquid coating agent corresponding to the volume of the coating gap.

[0005] If the amount of liquid coating agent injected into the coating gap is less than the volume of the coating gap, an uncoated area (a so-called short) will occur on the surface of the molded substrate. Conversely, if the amount of liquid coating agent injected into the coating gap is more than the volume of the coating gap, the excess liquid coating agent will leak out from the parting surface between the molds (a so-called overflow).

[0006] Therefore, in-mold coating injection devices have been developed to inject a predetermined amount of liquid coating agent (such as thermosetting paint, hereinafter simply referred to as paint) into the coating gap (see Patent Document 1). Figures 6 and 7 of Patent Document 1 describe an in-mold coating injection device in which a metering cylinder is interposed in the middle of a circulation path in which the paint is circulated by a circulation pump, and an injection device for injecting a predetermined amount of paint measured by the metering cylinder into the coating gap is provided in the circulation path downstream of the metering cylinder.

[0007] However, in this structure where the metering cylinder and the injection device are separate and connected by piping, when the paint inside the metering cylinder is pushed out and injected into the coating gap from the injection device, pressure loss occurs in the piping connecting the metering cylinder and the injection device, causing the piping to expand slightly, making it impossible to expect precise quantitative accuracy of the injected paint. In particular, when the amount of paint injected into the coating gap per injection is small (e.g., a few CCs), such as when the film thickness of the paint applied to the surface of the molded substrate is 0.1 mm or less, it becomes difficult to inject an appropriate amount of paint commensurate with the volume of the coating gap, and depending on the usage conditions, the aforementioned short circuits and overflows may occur.

[0008] To address these problems, Figures 1 and 2 of Patent Document 1 describe an in-mold coat injection device in which a metering and injection unit, which integrates the functions of a metering cylinder and an injection device, is installed in the middle of a circulation path through which paint is circulated by a circulation pump, and a predetermined amount of paint is injected into the coating gap by the metering and injection unit. With this configuration, since the metering and injection unit measures and injects the paint, pressure loss and expansion of the piping connecting the metering cylinder and the injection device do not occur as described above. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Patent No. 3422843 [Overview of the project] [Problems that the invention aims to solve]

[0010] However, the in-mold coating injection apparatus described in Figures 1 and 2 of Patent Document 1 circulates the paint within a circulation path to suppress heat transfer from the mold to the paint. This requires a circulation path and a circulation pump, resulting in a larger and more complex system.

[0011] Furthermore, after the end of the day's operation, it is necessary to drain all the paint remaining in the circulation path to prevent the paint inside the path from hardening. Here, since the circulation path requires the installation of a circulation pump and a paint tank along its course, the amount of paint introduced into the equipment is limited to a certain volume. Therefore, when comparing the amount of paint drained from the circulation path at the end of the day with the amount of paint required to coat the molded substrates during a day's operation, the material (paint) yield cannot be said to be good. In particular, when the size of the molded substrate is small and the film thickness of the paint applied to the surface is 0.1 mm or less, the amount of paint required for coating is small, while the amount of paint remaining inside the circulation path is relatively large, resulting in an extremely poor yield.

[0012] Furthermore, if a one-component, heat-curing paint is used, mixing the curing initiator into the paint at the start of the workday imposes a pot life (the time it takes for curing to begin even at room temperature) of approximately 12 hours. This necessitates draining the paint from the circulation system at the end of the workday, requiring paint draining work and resulting in the waste of all paint remaining inside the circulation system.

[0013] Furthermore, in the in-mold coating injection device described in Figures 1 and 2 of Patent Document 1, the metering and injection space (hereinafter referred to as the cylinder) of the metering and injection section is formed into a long, narrow shape, and a piston that moves up and down inside it is formed into a long, narrow rod shape. When the piston rises and paint is guided into the cylinder from the top, the injection port at the bottom of the cylinder is sealed by the surface of the molded substrate, so that a predetermined amount of paint is accumulated in the cylinder. In this way, there is no gate valve to open and close the injection port at the bottom of the cylinder, and the injection port is sealed by the surface of the molded substrate inside the mold to accumulate a predetermined amount of paint in the cylinder. Therefore, there is a possibility that the paint inside the cylinder may leak out of the injection port into the mold, and quantitative accuracy may become an issue.

[0014] Furthermore, by sealing the injection port at the bottom of the cylinder with the surface of the molded substrate inside the mold, paint is accumulated inside the cylinder, and the surface of the molded substrate inside the mold is used as a gate valve for the injection port at the bottom of the cylinder. Therefore, the cylinder needs to be embedded in the thick part of the mold so that the injection port at the bottom of the cylinder connects to the inner surface of the mold cavity. As a result, the paint inside the cylinder hardens due to the heat from the mold, and when the piston is lowered to inject the paint from the cylinder into the mold through the injection port, it may not be possible to properly inject the paint into all corners.

[0015] Considering the above circumstances, the object of the present invention is to provide a compact in-mold coating injection device that offers high accuracy in the amount of liquid coating agent injected, good yield of the liquid coating agent. [Means for solving the problem]

[0016] According to the present invention, which was devised to achieve the above objective, an in-mold coating injection device is provided for pressing one mold so as to cover the molded substrate with another mold, and injecting a predetermined amount of liquid coating agent into the coating gap between the inner surface of the other mold and the surface of the molded substrate, comprising: an injection device body attached to the other mold; an injection port provided at the tip of the injection device body for injecting liquid coating agent into the coating gap; a metering cylinder provided inside the injection device body connected to the injection port; a piston that is movable axially inside the metering cylinder; a supply port provided on the side of the injection device body connected to the metering cylinder; and a supply passage for the liquid coating agent connected to the supply port, the piston moving along the metering cylinder An in-mold coating injection device is provided, comprising: a supply valve that closes the supply passage when the piston moves in the discharge direction to reduce the volume of the metering cylinder and opens the supply passage when the piston moves in the suction direction to increase the volume of the metering cylinder; a gate valve that is axially slidable on the piston and moves by sliding to an open position that opens the inlet and a closed position that closes the inlet; and an actuator that, after filling the metering cylinder with a predetermined amount of liquid coating agent by closing the gate valve and moving the piston in the suction direction to guide the liquid coating agent from the supply port into the metering cylinder, opens the gate valve and moves the piston in the discharge direction to discharge a predetermined amount of liquid coating agent from the inlet.

[0017] In the in-mold coating injection apparatus according to the present invention, the supply valve may be a check valve that allows the liquid coating agent to flow from the supply passage to the metering cylinder and prevents it from flowing from the metering cylinder to the supply passage (Claim 2).

[0018] In the in-mold coating injection device according to the present invention, the actuator may have a piston operating flange formed on a portion of the piston protruding from the metering cylinder to move the piston in the axial direction of the metering cylinder, a piston operating cylinder formed to house the piston operating flange so as to be movable along the axial direction of the metering cylinder, a gate valve operating flange formed on a portion of the gate valve protruding from the piston to move the gate valve in the axial direction of the piston, a gate valve operating cylinder formed by connecting the gate valve operating flange to the piston operating cylinder so as to be movable along the axial direction of the piston, and a fluid pressure switching means that can switch between a metering mode in which fluid pressure is applied to the upper surface of the gate valve operating flange and the lower surface of the piston operating flange to close the inlet of the gate valve and move the piston in the suction direction, and an injection mode in which fluid pressure is applied to the lower surface of the gate valve operating flange and the upper surface of the piston operating flange to open the inlet of the gate valve and move the piston in the discharge direction (Claim 3).

[0019] In the in-mold coating injection device according to the present invention, the liquid coating agent is a one-component curing type thermosetting paint, and a cooling water passage may be formed inside the injection device body so as to surround the flow path of the liquid coating agent discharged from the metering cylinder to the injection port (Claim 4). [Effects of the Invention]

[0020] The in-mold coating injection device according to the present invention can provide the following effects. (1) By using the metering cylinder for the liquid coating agent as an extrusion cylinder for the liquid coating agent, the piping connecting the metering cylinder and the extrusion cylinder becomes unnecessary, and the discharge accuracy of the liquid coating agent is improved because the inlet is closed with a gate valve when the liquid coating agent is guided into the metering cylinder. (2) The liquid coating agent introduced into the metering cylinder from the supply port through the supply passage is extruded from the injection port by the piston, and since the circulation path and circulation pump of the liquid coating agent described in the prior art are not used, there is no need to take out and discard the paint remaining in the circulation path and circulation pump after work, and the material yield of the liquid coating agent is improved. (3) Since the circulation path and circulation pump of the liquid coating agent are not used, the entire apparatus can be configured compactly, and the material yield of the liquid coating agent is increased.

Brief Description of the Drawings

[0021] [Figure 1] It is a cross-sectional view showing the whole system of the in-mold coat injection device according to an embodiment of the present invention. [Figure 2] It is a cross-sectional view when the in-mold coat injection device of FIG. 1 starts measurement. [Figure 3] It is a cross-sectional view when measurement following FIG. 2 is completed. [Figure 4] It is a cross-sectional view when injection following FIG. 3 starts. [Figure 5] It is a cross-sectional view when injection following FIG. 4 is completed. [Figure 6] It is an explanatory view showing the cooling water passage, where (a) is a perspective view and (b) is a cross-sectional view.

Modes for Carrying Out the Invention

[0022] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in such embodiments are merely examples for facilitating the understanding of the invention, and do not limit the present invention unless otherwise specified. In the present specification and drawings, elements having substantially the same functions and configurations are denoted by the same reference numerals to omit duplicate descriptions, and elements not directly related to the present invention are not shown.

[0023] (Outline of the In-Mold Coat Injection Device 1) As shown in Figure 1, the in-mold coating injection apparatus 1 according to the present invention presses one mold 4 against one mold 3 that holds the molding substrate 2 so as to cover the molding substrate 2, and injects a predetermined amount of liquid coating agent 6 into the coating gap 5 between the inner surface of the other mold 4 and the surface of the molding substrate 2.

[0024] As shown in Figure 2, which is an enlarged view of the main part of Figure 1, the in-mold coating injection device 1 according to one embodiment of the present invention comprises an injection device body 7 attached to the other mold 4, an injection port 8 provided at the tip of the injection device body 7 for injecting liquid coating agent 6 into the coating gap 5, a metering cylinder 9 connected to the injection port 8 and provided inside the injection device body 7, a piston 10 that is axially movable inside the metering cylinder 9, a supply port 11 connected to the metering cylinder 9 and provided on the side of the injection device body 7, and a supply valve 13 provided in the supply passage 12 for the liquid coating agent 6 connected to the supply port 11, which closes the supply passage 12 when the piston 10 moves in the discharge direction that reduces the volume of the metering cylinder 9, and opens the supply passage 12 when the piston 10 moves in the suction direction that increases the volume of the metering cylinder 9.

[0025] Furthermore, as shown in Figure 2, the in-mold coating injection device 1 according to this embodiment includes a gate valve 14 that is axially slidable on a piston 10 and moves by sliding to an open position that opens the injection port 8 and a closed position that closes the injection port 8, and an actuator 15 that, as shown from Figure 2 to Figure 3, sets the gate valve 14 to the closed position and moves the piston 10 in the suction direction to guide the liquid coating agent 6 from the supply port 11 into the metering cylinder 9, thereby filling the metering cylinder 9 with a predetermined amount of liquid coating agent 6, and then, as shown from Figure 4 to Figure 5, sets the gate valve 14 to the open position and moves the piston 10 in the discharge direction to discharge a predetermined amount of liquid coating agent 6 from the injection port 8. The following describes each component.

[0026] (Mold, coating gap 5) As shown in Figure 1, the mold consists of one mold 3 (hereinafter also referred to as the lower mold 3) which is provided with a convex core 16 into which a separately molded molding substrate 2 is mounted, and the other mold 4 (hereinafter also referred to as the upper mold 4) which is positioned opposite to it and has a cavity 17 recessed so that a predetermined coating gap 5 (for example, 50 μm to 100 μm) is formed between it and the outer surface of the molding substrate 2 mounted on the core 16 of the lower mold 3. The upper mold 4 is attached to the lower surface of the upper platen 18 with bolts (not shown) via an insulating plate 52, and the lower mold 3 is attached to the upper surface of the lower platen 19 with bolts (not shown). As the lower platen 19 moves vertically relative to the upper platen 18, the lower mold 3 moves closer to and further away from the upper mold 4, causing the mold to clamp and open.

[0027] As shown in Figure 1, a runner groove 20 is formed on the butt joint surface (parting surface) of the upper mold 4 with the lower mold 3 to supply a liquid coating agent 6 (for example, a one-component thermosetting paint, hereinafter simply referred to as paint) to the coating gap 5 between the outer surface of the molded substrate 2 and the inner surface of the cavity 17 of the upper mold 4 during mold clamping. The runner groove 20 contains a runner 2a that was generated when the molded substrate 2 was molded by another molding die (not shown) instead of the upper mold 4. As shown in Figures 4 and 5, the paint 6 is injected into the coating gap 5 along the runner 2a by passing through the runner groove 20. The upper mold 4 is provided with a heating mechanism (electrical resistance wire, etc.) (not shown) to heat and cure the paint 6 injected into the coating gap 5 through the runner groove 20. The heat insulating plate 52 interposed between the upper mold 4 and the upper platen 18 functions to suppress the transfer of heat from the upper mold 4 to the upper platen 18. This reduces the heat input from the upper platen 18 to the injection device body 7, thereby suppressing the progress of the curing reaction of the paint 6 (one-component thermosetting paint) guided into the inside of the injection device body 7 (cylinder 9).

[0028] (Injection device body 7) As shown in Figure 2, in this embodiment, the injection device body 7 consists of a three-stage cylindrical body in which a small diameter section 7a, a medium diameter section 7b, and a large diameter section 7c are connected from bottom to top, and is equipped with a mounting flange 43 provided on the outer circumferential surface of the large diameter section 7c. The mounting flange 43 is attached to the upper platen 18 by bolts 44. The upper mold 4 has mounting holes 21 for housing the injection device body 7, which are formed through the upper and lower surfaces so as to connect with the runner groove 20. The mounting holes 21 consist of a small diameter hole section 21a with a hole diameter corresponding to the small diameter section 7a of the injection device body 7, and a medium diameter hole section 21b with a hole diameter larger than the medium diameter section 7b of the injection device body 7, and a predetermined gap 54 is formed between the medium diameter hole section 21b and the medium diameter section 7b. The gap 54 functions as an air insulation layer that suppresses the transfer of heat from the upper mold 4 to the injection device body 7.

[0029] As shown in Figure 2, the upper platen 18 has a through hole 24 with a larger diameter than the large diameter portion 7c to accommodate the large diameter portion 7c of the injection device body 7. A gap 25 is formed between the through hole 24 and the large diameter portion 7c of the injection device body 7, and the gap 25 functions as an air insulation layer that prevents a small amount of heat transferred from the upper mold 4 to the upper platen 18 via the insulation plate 52 from being transferred to the injection device body 7.

[0030] As shown in Figure 2, an insulating sleeve 22 is interposed between the small-diameter portion 7a of the injection device body 7 and the small-diameter hole portion 21a of the mounting hole 21. The insulating sleeve 22 suppresses the transfer of heat from the upper mold 4 to the injection device body 7, thereby suppressing the progress of the curing reaction of the paint 6 (one-component thermosetting paint) guided into the interior of the injection device body 7. An insulating flange 22a is integrally provided at the upper end of the insulating sleeve 22. The insulating flange 22a is formed to be sandwiched between the step from the small-diameter portion 7a to the medium-diameter portion 7b of the injection device body 7 and the step from the small-diameter hole 21a to the medium-diameter hole 21b of the mounting hole 21, thereby suppressing the transfer of heat from the upper mold 4 to the injection device body 7, and preventing the paint 6 (one-component thermosetting paint) guided into the interior of the injection device body 7 from receiving heat from the upper mold 4 and suppressing the progress of the curing reaction. Furthermore, the heat-insulating flange 22a is slightly compressed when the bolt 44 is screwed in, and also functions as a packing to prevent the paint 6 in the runner groove 20 from leaking upward from between the mounting hole 21 and the injection device body 7.

[0031] As shown in Figure 2, a heat insulating ring 23 is interposed between the step from the large diameter section 7c to the medium diameter section 7b of the injection device body 7 and the upper surface of the upper mold 4 to suppress the transfer of heat from the upper mold 4 to the injection device body 7. The heat insulating ring 23 suppresses the transfer of heat from the upper mold 4 to the injection device body 7, and the paint 6 (one-component thermosetting paint) guided into the inside of the injection device body 7 receives heat from the upper mold 4, suppressing the progress of the curing reaction. In addition, when the bolt 44 is screwed in, the heat insulating ring 23 is squeezed between the lower surface of the large diameter section 7c and the upper surface of the upper mold 4 and is slightly compressed. The force of its recovery causes the male threaded portion of the bolt 44 and the female threaded portion of the screw hole for the bolt 44 formed in the upper platen 18 to press against each other in the axial direction, thus also functioning as a bolt 44 anti-loosening agent. Furthermore, the insulating flange 22a of the insulating sleeve 22 also slightly deforms when the bolt 44 is screwed in, exhibiting restorative force, and thus also functions as a bolt 44 anti-loosening agent.

[0032] (Measuring cylinder 9, piston 10) As shown in Figure 2, a measuring cylinder 9 for containing a predetermined amount of paint 6 is formed inside the injection device body 7. The measuring cylinder 9 is formed inside the large-diameter portion 7c of the injection device body 7 and is positioned inside the injection device body 7 in a location least affected by the heat of the upper mold 4, thanks to the aforementioned heat insulating sleeve 22, heat insulating ring 23, gap 25 (air insulation layer), and gap 54 (air insulation layer). In this embodiment, the measuring cylinder 9 is positioned above the upper surface of the upper mold 4 and above the heat insulating ring 23. A piston 10 is provided inside the measuring cylinder 9 so as to be movable in the axial direction (up and down direction). The piston 10 comprises a piston body portion 10a with a diameter that slides against the measuring cylinder 9, and a piston projection portion 10b provided on the upper part of the piston body portion 10a that protrudes from the measuring cylinder 9.

[0033] (Inlet 8, Supply port 11) As shown in Figure 2, a passage hole 26 smaller in diameter than the metering cylinder 9 is formed inside the medium-diameter section 7b and small-diameter section 7a of the injection device body 7, connected to the metering cylinder 9. A conical valve seat 27 is formed at the lower end of the passage hole 26, and an injection port 8 is formed at the lower end of the valve seat 27 so as to face the runner groove 20. The injection port 8 injects the paint 6 from the metering cylinder 9 into the runner groove 20 through the passage hole 26. It is closed when the lower end of the gate valve 14 seats on the valve seat 27, and opened when the lower end of the gate valve 14 moves away from the valve seat 27. In addition, a supply port 11 for supplying paint 6 to the metering cylinder 9 is provided on the side of the large-diameter section 7c of the injection device body 7, connected to the metering cylinder 9.

[0034] (Supply passage 12) As shown in Figure 2, a supply passage 12 for supplying paint 6 to a metering cylinder 9 is connected to a supply port 11 on the side of the large-diameter portion 7c of the injection device body 7. The supply passage 12 is inserted through a hole formed inside the upper platen 18 that is larger in diameter than the outer diameter of the supply passage 12. A gap 53 is formed between the hole and the supply passage 12. The gap 53 acts as an air insulation layer to prevent heat from the upper platen 18 from being transferred to the paint 6 flowing through the supply passage 12.

[0035] (Supply valve 13) As shown in Figure 1, the supply passage 12 is provided with a supply valve 13 that opens when the piston 10 moves in the suction direction (upward) to increase the volume of the metering cylinder 9, as shown in Figures 2 and 3, and closes when the piston 10 moves in the discharge direction (downward) to decrease the volume of the metering cylinder 9, as shown in Figures 4 and 5. In this embodiment, the supply valve 13 is a check valve that allows the paint 6 to flow from the supply passage 12 to the metering cylinder 9 and prevents it from flowing from the metering cylinder 9 to the supply passage 12. However, an on / off valve that opens and closes the supply passage 12 may also be controlled as described above. As shown in Figure 1, a paint tank 28 containing the paint 6 is connected to the upstream side of the supply valve 13 via piping 29.

[0036] (Gate valve 14) As shown in Figure 2, a hole 30 is formed through the piston 10 in the axial direction (up and down direction), and a gate valve 14, which is elongated in the vertical direction, is mounted in the hole 30 so as to be slidable in the axial direction. The gate valve 14 has a medium-diameter portion 14a that slides in the hole 30, a small-diameter portion 14b integrally provided below the medium-diameter portion 14a, and a large-diameter portion 14c integrally provided above the medium-diameter portion 14a. The small-diameter portion 14b is housed in the passage hole 26 with a predetermined gap in the diametrical direction, and has a conical tip valve portion 14d at its lower end so as to seat on the valve seat 27. The large-diameter portion 14c has a diameter that slides in the hole 31 formed in the axial direction inside the piston projection 10b, and its upper part protrudes upward from the piston projection 10b. In this gate valve 14, when it rises, the tip valve portion 14d separates from the valve seat 27 and opens the inlet 8, which is the open valve position, and when it descends, the tip valve portion 14d sits on the valve seat 27 and closes the inlet 8, which is the closed valve position.

[0037] (Actuator 15) As shown in Figure 1, the piston 10 and the gate valve 14 are raised and lowered as appropriate by the actuator 15. As shown in Figures 2 and 3, the actuator 15 moves in the suction direction, lowering the gate valve 14 to the closed position and raising the piston 10 to guide the liquid coating agent 6 from the supply port 11 into the metering cylinder 9, thereby filling the metering cylinder 9 with a predetermined amount of liquid coating agent 6. Then, as shown in Figures 4 and 5, the actuator 15 moves in the discharge direction, raising the gate valve 14 to the open position and lowering the piston 10 to discharge a predetermined amount of liquid coating agent 6 from the inlet 8.

[0038] As shown in Figure 2, the actuator 15 includes a piston operating flange 32 formed on the portion of the piston 10 that protrudes from the metering cylinder 9 (piston protrusion 10b) to move the piston 10 in the axial direction of the metering cylinder 9, a piston operating cylinder 33 formed to house the piston operating flange 32 so as to be movable along the axial direction of the metering cylinder 9, a gate valve operating flange 34 formed on the portion of the gate valve 14 that protrudes from the piston 10 (gate valve protrusion 14e) to move the gate valve 14 in the axial direction of the piston 10, and a gate valve operating cylinder 35 formed by connecting the gate valve operating flange 34 to the piston operating cylinder 33 so as to be movable along the axial direction of the piston 10.

[0039] As shown in Figure 2, the piston operating cylinder 33 and the gate valve operating cylinder 35 are formed inside a cylinder block 37, which is attached to the upper platen 18 via a support column 36. The cylinder block 37 has a first passage 38 for applying fluid pressure to the upper surface of the gate valve operating flange 34 and the lower surface of the piston operating flange 32, and a second passage 39 for applying fluid pressure to the lower surface of the gate valve operating flange 34 and the upper surface of the piston operating flange 32. The first passage 38 includes a passage 38a connecting a hole formed on one side of the cylinder block 37 to the portion of the gate valve operating cylinder 35 above the gate valve operating flange 34, and a passage 38b connecting the middle of passage 38a to the portion of the piston operating cylinder 33 below the piston operating flange 32. The second passage 39 connects a hole formed on the other side of the cylinder block 37 to the portion of the piston operating cylinder 33 above the piston operating flange 32.

[0040] Furthermore, the actuator 15 is equipped with a fluid pressure switching means 40 (see Figure 1) that can be switched between a metering mode, in which a fluid (air, water, oil, etc.) is supplied to the first passage 38 to apply fluid pressure to the upper surface of the gate valve operating flange 34 and the lower surface of the piston operating flange 32, causing the gate valve 14 to close the inlet 8 and the piston 10 to move in the suction direction, and an injection mode, in which a fluid is supplied to the second passage 39 to apply fluid pressure to the lower surface of the gate valve operating flange 34 and the upper surface of the piston operating flange 32, causing the gate valve 14 to open the inlet 8 and the piston 10 to move in the discharge direction, as shown in Figures 2 to 3.

[0041] (Fluid pressure switching means 40) As shown in Figure 1, the fluid pressure switching means 40 includes a switching valve 41 connected to a first passage 38 and a second passage 39, a tank T (air tank, water tank, oil tank, etc.) containing a fluid (air, water, oil, etc.) at a predetermined pressure to supply fluid pressure (air pressure, water pressure, hydraulic pressure, etc.), a pump P that pressurizes and supplies the fluid to the tank T, and a control unit C that appropriately switches the switching valve 41. In this embodiment, an example is shown in which air is used as the fluid and an electromagnetic solenoid valve is used for the switching valve 41.

[0042] In the electromagnetic solenoid valve (switching valve 41) shown in Figure 1, if electricity is not supplied to the solenoid 41a of the switching valve 41 from the control unit C, the box is pushed to the right by the spring 41b, and the parallel circuit becomes functional. As a result, air in the tank T is supplied to the first passage 38, and air in the second passage 39 is exhausted from the exhaust silencer 42. As a result, as shown from Figure 2 to Figure 3, the gate valve 14 descends to the closed position, the piston moves upward (in the intake direction), and the system enters metering mode.

[0043] On the other hand, when electricity is supplied to the solenoid 41a from the control unit C shown in Figure 1, the solenoid 41a is excited, the box moves to the left, and the cross circuit becomes functional. As a result, the air in the tank T is supplied to the second passage 39, and the air in the first passage 38 is exhausted from the exhaust silencer 42. This causes the gate valve 14 to rise to the open position, as shown from Figure 4 to Figure 5, the piston to move downward (in the discharge direction), and the injection mode is activated.

[0044] (Cooling water passage) As shown in Figure 6(a), a cooling water passage 45 is formed inside the injection device body 7, surrounding the flow path of the liquid coating agent 6 (one-component curing thermosetting paint) discharged from the inlet 8 through the metering cylinder 9 and the passage hole 26. The cooling water passage 45 is formed in a double helix shape surrounding the metering cylinder 9 and the passage hole 26. Cooling water is introduced from an inlet 46 formed on the upper left side of the injection device body 7, descends counterclockwise when viewed from above, folds back at the lower part of the injection device body 7, rises clockwise, and is discharged from an outlet 47 formed on the upper right side of the injection device body 7. The injection device body 7, in which such a complexly shaped cooling water passage 45 is formed, is manufactured by a metal 3D printer, lost-wax casting, or the like. The cooling water flowing through the cooling water passage 45 prevents the liquid coating agent 6 (one-component curing type thermosetting paint) contained in the metering cylinder 9 and passage hole 26 from being excessively heated by the heat from the upper mold 4, thereby suppressing the progression of the curing reaction.

[0045] (Start of measurement) When introducing a predetermined amount of paint 6 into the in-mold coating injection device 1 shown in Figure 1, fluid is first supplied to the first passage 38, as shown in Figure 2. This causes the gate valve 14 to descend to the closed position, and the piston 10 to rise. As a result, negative pressure is created inside the metering cylinder 9, and the paint 6 is introduced into the metering cylinder 9 via the supply valve 13 (check valve). Here, if the tip valve portion 14d of the gate valve 14 were to separate from the valve seat 27, the paint 6 would leak out of the injection port 8. Therefore, a leak prevention spring 48 is provided on the ceiling surface of the cylinder block 37 to bias the gate valve 14 downward, pressing the tip valve portion 14d against the valve seat 27. As a result, even if the actuator 15 malfunctions or becomes uncontrollable due to an emergency stop, the paint 6 inside the device will not leak into the mold. The fluid above the piston operating flange 32 inside the piston operating cylinder 33 is discharged from the second passage 39 as the piston operating flange 32 rises.

[0046] (Measurement completed) As shown in Figure 3, the piston operating flange 32 of the piston 10 comes into contact with the ceiling surface of the piston operating cylinder 33, causing the piston 10 to reach top dead center, a predetermined amount of paint 6 to accumulate in the metering cylinder 9, and metering is completed.

[0047] (Start injection) Next, fluid is supplied to the second passage 39 as shown in Figure 4 in order to inject a predetermined amount of paint 6 into the runner groove 20 from the inlet 8. This causes the gate valve 14 to rise, opening the inlet 8, and the piston 10 to descend, reducing the volume of the metering cylinder 9. As a result, the paint 6 in the metering cylinder 9 is injected into the runner groove 20 from the inlet 8. At this time, the supply valve 13 (check valve) prevents the paint 6 in the metering cylinder 9 from flowing back into the tank 28 (see Figure 1). Furthermore, the fluid below the piston operating flange 32 in the piston operating cylinder 33 is discharged from the first passage 38 as the piston operating flange descends, and the fluid above the gate valve operating flange 32 in the gate valve operating cylinder 35 is discharged from the first passage 38 as the gate valve operating flange 34 rises.

[0048] (Injection completed) As shown in Figure 5, the piston 10 reaches its bottom dead center when the lower surface of the stroke adjustment ring 49 on the piston 10 contacts the upper surface of the injection device body 7, completing the injection of paint 6. By appropriately changing the thickness t of the stroke adjustment ring 49, the stroke S (see Figure 3) from top dead center to bottom dead center can be adjusted, and the amount of paint 6 injected can be adjusted. On the other hand, the gate valve 14 is set to an open position when it contacts the bottom surface of a stopper bolt 51 that is screwed into a screw hole 50 that penetrates the ceiling surface of the cylinder block 37. By appropriately changing the screwing position of the stopper bolt 51, the distance between the tip valve portion 14d of the gate valve 14 in the open position and the valve seat 27 can be adjusted, and the discharge rate (amount discharged per unit time) of the paint 6 discharged from the injection port 8 can be adjusted.

[0049] (Effects / Actions) According to the in-mold coating injection device 1 of this embodiment, as shown in Figures 2 to 3, the metering cylinder 9 for the paint 6 is also used as the extrusion cylinder for the paint 6, as shown in Figures 4 to 5. This eliminates the need for piping to connect the metering cylinder 9 and the extrusion cylinder. Furthermore, since the injection port 8 is closed with a gate valve 14 when guiding the paint 6 into the metering cylinder 9, the accuracy of the paint 6 metering is improved.

[0050] Furthermore, as shown in Figure 1, the paint 6 guided from the supply port 11 into the metering cylinder 9 via the supply passage 12 is pushed out from the injection port 8 by the piston 10. Since the paint circulation path and circulation pump described in the conventional technology are not used, there is no need to remove and dispose of any paint remaining in the circulation path and circulation pump after the end of the workday, and the material yield of the paint 6 is improved.

[0051] Furthermore, since no paint circulation path or circulation pump is used, the entire device can be made compact, and the material yield of the paint 6 is increased. Thus, with the in-mold coat injection device 1 according to this embodiment, the accuracy of the amount of paint 6 injected is high, the yield of paint 6 is good, and the device is compact.

[0052] Although preferred embodiments of the present invention have been described above with reference to the attached drawings, it goes without saying that the present invention is not limited to the embodiments described above, and that various modifications or alterations within the scope of the claims also fall within the technical scope of the present invention. [Industrial applicability]

[0053] The present invention can be used in an in-mold coating injection device that presses one mold against another mold so as to cover the molded substrate, and injects a predetermined amount of liquid coating agent into the coating gap between the inner surface of the other mold and the surface of the molded substrate. [Explanation of Symbols]

[0054] 1. In-mold coating injection device 2 Molding base material 3. One of the molds (lower mold) 4. The other mold (upper mold) 5 Coating gap 6. Liquid coating agent (paint) 7 Injection device body 8 Inlet 9 Measuring cylinder 10 pistons 11 supply ports 12 Supply passage 13. Supply valve (check valve) 14 Gate valve 15 Actuators 32 Piston operating flange 33 Piston Actuating Cylinder 34. Flange for gate valve operation 35 Cylinder for operating gate valve 40 Fluid pressure switching means 45 Cooling water passage

Claims

1. An in-mold coating injection device that presses one mold against another mold so as to cover the molding substrate, and injects a predetermined amount of liquid coating agent into the coating gap between the inner surface of the other mold and the surface of the molding substrate, An injection device body attached to the other mold, The injection device body has an inlet at its tip for injecting the liquid coating agent into the coating gap, A measuring cylinder is provided inside the main body of the injection device, connected to the injection port, A piston that can move axially within the metering cylinder, A supply port provided on the side of the injection device body is connected to the metering cylinder, A supply valve is provided in the supply passage for the liquid coating agent connected to the supply port, which closes the supply passage when the piston moves in the discharge direction that reduces the volume of the measuring cylinder, and opens the supply passage when the piston moves in the suction direction that increases the volume of the measuring cylinder. A gate valve is mounted on the piston so as to be axially slidable, and moves by sliding to an open position that opens the inlet and a closed position that closes the inlet. An in-mold coating injection device comprising an actuator for discharging a predetermined amount of the liquid coating agent from the injection port by setting the gate valve to the closed position and moving the piston in the suction direction to guide the liquid coating agent from the supply port into the metering cylinder, thereby filling the metering cylinder with a predetermined amount of the liquid coating agent, and then setting the gate valve to the open position and moving the piston in the discharge direction to discharge the predetermined amount of the liquid coating agent from the injection port.

2. The in-mold coating injection apparatus according to claim 1, characterized in that the supply valve is a check valve that allows the liquid coating agent to flow from the supply passage to the metering cylinder and prevents it from flowing from the metering cylinder to the supply passage.

3. The actuator is A piston operating flange is formed on the portion of the piston that protrudes from the metering cylinder in order to move the piston in the axial direction of the metering cylinder, A piston operating cylinder formed to house the piston operating flange so as to be movable along the axial direction of the metering cylinder, A gate valve operating flange is formed on the portion of the gate valve that protrudes from the piston in order to move the gate valve in the axial direction of the piston, A gate valve operating cylinder is formed by connecting the gate valve operating flange to the piston operating cylinder so as to house it movably along the axial direction of the piston, The in-mold coat injection device according to claim 1 or 2, characterized in that it has a fluid pressure switching means that can switch between a metering mode in which fluid pressure is applied to the upper surface of the gate valve operating flange and the lower surface of the piston operating flange, causing the gate valve to close the inlet and the piston to move in the suction direction, and an injection mode in which fluid pressure is applied to the lower surface of the gate valve operating flange and the upper surface of the piston operating flange, causing the gate valve to open the inlet and the piston to move in the discharge direction.

4. The aforementioned liquid coating agent is a one-component, curing type thermosetting paint. The in-mold coating injection device according to claim 3, characterized in that a cooling water passage is formed inside the injection device body so as to surround the flow path of the liquid coating agent discharged from the metering cylinder to the injection port.

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