Blow molding mechanism

Abstract

To provide a technique capable of reducing the possibility of breakage of a suction circuit in a blow molding mechanism equipped with the suction circuit.SOLUTION: The blow molding mechanism 1 forms a final molded article by blowing gas into an intermediate molded article held in a mold. The blow molding mechanism 1 is equipped with a suction circuit 40 sucking the final molded product to attract the same to the mold and a suppression part 50 suppressing the pressure in the suction circuit 40 to a predetermined value or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a blow molding mechanism. [Background technology]

[0002] Patent Document 1 discloses blow molding, in which a gas is blown into an intermediate molded product held in a mold to inflate the intermediate molded product to the shape of the inside of the mold, thereby forming a final molded product. Blow molding uses a mold that can be separated into multiple parts. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-151468 Summary of the Invention [Problem to be solved by the invention]

[0004] Once the blow molding is complete, the split mold is opened and the final molded product is removed. One method for removing the final molded product from the open split mold is to let the final molded product fall freely, but this can cause the final molded product to become unstable when the split mold is opened, and the final molded product may come into contact with the split mold during its free fall, resulting in scratches on the final molded product.

[0005] As a countermeasure, the inventors have considered a method of maintaining a stable posture of the final molded product by sucking it with a suction circuit and adhering it to a bottom mold or the like, and then allowing the final molded product to fall freely in that state. In the course of this investigation, the inventors have come to recognize the following problem.

[0006] If a hole is present in the final molded product due to molding defects or other reasons, the high-pressure gas blown into the molding process may pass through the hole and enter the suction circuit, exceeding the circuit's pressure resistance limit and potentially damaging the circuit.

[0007] The present disclosure has been made in light of these circumstances, and one exemplary purpose of one aspect thereof is to provide a technology that can reduce the risk of damage to a suction circuit in a blow molding mechanism that is equipped with a suction circuit. [Means for solving the problem]

[0008] In order to solve the above problems, one embodiment of the blow molding mechanism disclosed herein is a blow molding mechanism that blows gas into an intermediate molded product held in a mold to form a final molded product, and is equipped with a suction circuit that sucks the final molded product and adsorbs it to the mold, and a suppression unit that suppresses the pressure in the suction circuit to below a predetermined value.

[0009] Any combination of the above components, or mutual substitution of the components or expressions of the present disclosure between methods, devices, systems, etc., are also valid aspects of the present disclosure. [Effects of the Invention]

[0010] According to one aspect of the present disclosure, in a blow molding mechanism equipped with a suction circuit, the risk of the suction circuit being damaged can be reduced. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 2 is a diagram illustrating a configuration of a blow molding mechanism according to an embodiment. [Figure 2] 2 is a flowchart showing an example of the operation of the blow molding mechanism of FIG. 1. [Figure 3] 3(a) and 3(b) are diagrams showing the state of the blow molding mechanism after blow molding is completed. DETAILED DESCRIPTION OF THE INVENTION

[0012] The present disclosure will be described below based on preferred embodiments with reference to the drawings. The embodiments are illustrative and do not limit the disclosure, and all features and combinations described in the embodiments are not necessarily essential to the disclosure. In the embodiments, identical or equivalent components and members are designated by the same reference numerals, and redundant descriptions will be omitted as appropriate.

[0013] Before describing the embodiments of the present disclosure in detail, an overview of the embodiments will be described. The embodiments relate to a blow molding mechanism. The blow molding mechanism produces a final molded product by blowing gas into an intermediate molded product held in a mold via a blow circuit. The blow molding mechanism maintains the final molded product in a stable position by sucking the final molded product via a suction circuit and adhering it to a bottom mold or the like, and then allows the final molded product to free fall in that state. This prevents the final molded product from coming into contact with a split mold during free fall and being damaged. If a hole is formed in the final molded product due to a molding defect or the like, the high-pressure gas blown in by the blow circuit may pass through the hole and enter the suction circuit, exceeding the suction circuit's pressure limit and potentially damaging the suction circuit. Therefore, in this embodiment, the blow molding mechanism further includes a suppression unit that suppresses the pressure in the suction circuit below a predetermined value. The predetermined value may be, for example, a first threshold pressure or a second threshold pressure, as described below. The embodiments will be described in detail below.

[0014] FIG. 1 is a diagram showing a schematic configuration of a blow molding mechanism 1 according to an embodiment. The blow molding mechanism 1 is applied to an injection blow molding device that performs injection blow molding. Injection blow molding is a molding process that successively performs injection molding, which is the first molding stage, and blow molding, which is the second molding stage. Injection molding is performed with a fixed mold and an intermediate mold 20 (not shown) in a mold closed state, and blow molding is performed with a movable mold 10 and the intermediate mold 20 in a mold closed state. The intermediate mold 20 is a so-called rotating mold that is arranged between the fixed mold and the movable mold 10.

[0015] In injection molding, an intermediate molded product (not shown) is molded. In blow molding, high-pressure gas (typically air) is blown into the interior of the intermediate molded product held by the movable mold 10 and the intermediate mold 20, causing the intermediate molded product to expand to the shape inside the movable mold 10, thereby forming a final molded product. In the following, an example will be described in which the intermediate molded product is a preform and the final molded product is a bottle container 200.

[0016] The blow molding mechanism 1 includes a movable mold 10, an intermediate mold 20, a blow circuit 30, a suction circuit 40, and a suppression unit 50. The movable mold 10 and the intermediate mold 20 are shown in horizontal cross section as viewed from above. Details of the suppression unit 50 will be described later.

[0017] The solid areas in the cross section of the bottle container 200 indicate the areas where the preform is stretched by blow molding. However, in reality, there is no clear distinction between the areas that are stretched by blow molding and the areas that are not. For this reason, the boundary between the solid areas and the hatched areas in the cross section of the bottle container 200 in Figure 1 only indicates an approximate position.

[0018] The bottle container 200 has a mouth 201, a main body 202, and a bottom 203. The mouth 201, the main body 202, and the bottom 203 are continuous parts of the shape of the bottle container 200 and have no clear boundary between them. In this embodiment, the mouth 201 is the part near the end of the first side in the first direction of the bottle container 200, that is, the part including the surface 251 of the fringe 206 on the first side in the first direction and the male thread 207 that screws into the female thread of a cap (not shown) of the bottle container 200.

[0019] The bottom 203 is a portion that is molded by the bottom mold 13, which will be described later. Specifically, the bottom 203 is a portion near the end of the second side in the first direction of the bottle container 200. The main body 202 is a portion that is molded by the second split mold 12, which will be described later. Specifically, the main body 202 is a portion of the bottle container 200 other than the mouth 201 and the bottom 203.

[0020] In Fig. 1, the movable mold 10 and the intermediate mold 20 are closed. The axial direction of the bottle container 200 in this state (the left-right direction in Fig. 1) is the same direction as the direction in which the intermediate mold 20 and the movable mold 10 open and close. Hereinafter, the direction in which the intermediate mold 20 and the movable mold 10 open and close (the left-right direction in Fig. 1) will be referred to as the "first direction," the right side of the drawing in the first direction will be referred to as the "first side," and the left side of the drawing in the first direction will be referred to as the "second side." In addition, the direction perpendicular to the first direction (the up-down direction in Fig. 1) will be referred to as the "second direction," the upper side of the drawing in the second direction will be referred to as the "third side," and the lower side of the drawing in the second direction will be referred to as the "fourth side."

[0021] The movable mold 10 includes a first-split mold 11, a second-split mold 12, and a bottom mold 13. The first-split mold 11 is a split mold that can be opened and closed in a second direction. The first-split mold 11 holds a mouth portion 201 when the mold is closed. The first-split mold 11 also releases the mouth portion 201 by opening after blow molding is completed. The first-split mold 11 is also called a split or mouth-split mold.

[0022] The second-split mold 12 is a split mold that can be opened and closed in a second direction. The second-split mold 12 molds the main body portion 202 in a closed state during blow molding. After the blow molding is completed, the second-split mold 12 is opened to release the main body portion 202. The second-split mold 12 is also called a blow mold.

[0023] The bottom mold 13 forms at least a part of the bottom 203 during blow molding.

[0024] The first split mold 11 is slidable in the second direction relative to the second split mold 12. The second split mold 12 is slidable in the second direction relative to the first split mold 11 and the bottom mold 13.

[0025] The blowing circuit 30 blows gas into the inside of the preform. The blowing circuit 30 includes a blowing pump 32 and a blowing pipe 34. The blowing pump 32 blows high-pressure gas into the inside of the preform via the blowing pipe 34.

[0026] The suction circuit 40 sucks the bottle container 200 and adsorbs it to the movable mold 10, in this example, the bottom mold 13. The suction circuit 40 has a suction pump 42 and a suction pipe 44 that communicates between the suction pump 42 and the inside of the movable mold 10. The suction pump 42 sucks gas from inside the movable mold 10 through the suction pipe 44, thereby sucking the bottle container 200 and adsorbing it to the bottom mold 13. The suction pump 42 may be a vacuum pump. In other words, the suction circuit 40 may be a vacuum circuit.

[0027] Fig. 2 is a flowchart showing an example of the operation of the blow molding mechanism 1 after blow molding is completed. Figs. 3(a) and 3(b) are diagrams showing the state of the blow molding mechanism 1 after blow molding is completed.

[0028] The suction circuit 40 starts suctioning at least a portion of the bottom 203 of the bottle container 200 (S12). Next, mold opening between the movable mold 10 and the intermediate mold 20 starts (S10). Specifically, the movable mold 10 moves to the second side in the first direction relative to the intermediate mold 20. The posture of the bottle container 200 at this point is the state shown in Fig. 1, i.e., the state in which the center line 300 of the bottle container 200 has not changed.

[0029] Next, the first-split mold 11 and the second-split mold 12 start opening (S14). Figure 3(a) shows the state immediately after the first-split mold 11 and the second-split mold 12 start opening. The first-split mold 11 and the second-split mold 12 may start opening at the same time, or the first-split mold 11 may start opening immediately after the second-split mold 12 starts opening.

[0030] The suction circuit 40 continues to suck the bottom 203 of the bottle container 200 even when the first-split mold 11 and the second-split mold 12 start to open. Therefore, the bottle container 200 remains in the same position as shown in Figure 1, i.e., the center line 300 of the bottle container 200 remains unchanged, even immediately after the first-split mold 11 and the second-split mold 12 start to open.

[0031] The suction force of the suction circuit 40 only needs to be strong enough to maintain the orientation of the bottle container 200 when the first-split mold 11 and the second-split mold 12 begin to open, and does not need to be strong enough to support the weight of the bottle container 200. For this reason, even if the suction circuit 40 continues to perform suction after the first-split mold 11 and the second-split mold 12 begin to open, the bottle container 200 may begin to fall freely due to its own weight. Specifically, the bottle container 200 may begin to fall freely in a direction perpendicular to the plane of the paper in Figure 3(b), from the front side to the back side.

[0032] Next, the suction circuit 40 stops suction between the start of mold opening of the first-split mold 11 and the second-split mold 12 and the completion of mold opening (S16). Note that if the suction force of the suction circuit 40 is strong, the pressure inside the suction tube 44 may not rise immediately just by stopping the suction, and the bottle container 200 may not begin to fall freely. Therefore, as a modified example, a circuit for feeding air may be connected to the suction tube 44, and after suction by the suction circuit 40 has stopped, gas may be fed into the suction tube 44 from that circuit for a short period of time to increase the pressure inside the suction tube 44.

[0033] As described above, the suction circuit 40 adsorbs the bottle container 200 to the bottom mold 13, so that the bottle container 200 maintains its orientation other than in the up-down direction (the direction of gravity) even immediately after the first split mold 11 and the second split mold 12 begin to open. This allows the bottle container 200 to begin free fall in a stable state where tilting of the center line 300 toward the third or fourth side in the second direction is suppressed. As a result, damage to the bottle container 200 due to contact with the split molds 11, 12 is suppressed.

[0034] If suction is not applied when the first-split mold 11 and the second-split mold 12 begin to open, a force (hereinafter referred to as a "mold release force") acts on the first-split mold 11 and the second-split mold 12 to pull the bottle container 200. The bottle container 200 may lose its position due to the mold release force. Also, when the first-split mold 11 and the second-split mold 12 begin to open, the bottle container 200 may become slightly caught on the first-split mold 11 or the second-split mold 12, causing it to lose its position. Furthermore, the bottle container 200 may lose its position due to slight vibrations that occur as the first-split mold 11 and the second-split mold 12 begin to open. In either case, the bottle container 200 may lose its position. In this case, the bottle container 200 may come into contact with the split molds 11, 12 and be damaged.

[0035] 2 is merely an example, and other steps may be added, the order of the steps may be changed, or some steps may be executed in parallel. For example, the order of S10 and S12 may be reversed. That is, the mold opening between the movable mold 10 and the intermediate mold 20 may start before the suction circuit 40 starts suction.

[0036] Defective injection molding can result in holes in the preform, an intermediate molded product, or in holes in the molded product during blow molding. Alternatively, defective blow molding can result in holes in the molded product during blow molding. In either case, as shown in FIG. 1, a hole 200a may be present in the bottle container 200, the final molded product. If a hole is present in the bottle container 200, the high-pressure gas blown into the molded product by the blow circuit during blow molding may enter the suction circuit 40, exceeding the pressure-resistance limit of the suction circuit 40 and causing damage to the suction circuit 40. Specifically, the suction pump 42 or the suction pipe 44 may be damaged.

[0037] Therefore, the blow molding mechanism 1 of the embodiment includes a suppression unit 50 that suppresses the pressure in the suction circuit 40 to a predetermined first threshold pressure or less, as shown in FIG.

[0038] The first threshold pressure may be determined based on the withstand pressure of the suction pump 42. For example, the first threshold pressure may be a pressure obtained by multiplying the withstand pressure of the suction pump 42 by a safety factor (e.g., 0.8). The first threshold pressure may be determined based on the withstand pressure of the suction tube 44. For example, the first threshold pressure may be a pressure obtained by multiplying the withstand pressure of the suction tube 44 by a safety factor (e.g., 0.8). Alternatively, the first threshold pressure may be a pressure obtained by multiplying the lower of the withstand pressure of the suction pump 42 and the withstand pressure of the suction tube 44 by a safety factor (e.g., 0.8).

[0039] In this embodiment, the suppression unit 50 includes a branch pipe 52 branching off from the suction pipe 44 and a valve 54 provided in the branch pipe 52. The branch pipe 52 is open to the atmosphere, although this is not limited to this.

[0040] The valve 54 opens when the pressure in the flow path of the branch pipe 52 on the suction circuit 40 side reaches or exceeds a predetermined second threshold pressure. The second threshold pressure is equal to or less than the first threshold pressure. If the high-pressure gas blown into the molded product by the blowing circuit 30 enters the suction circuit 40 due to a hole in the bottle container 200 and the pressure in the flow path of the suction pipe 44 and therefore the flow path of the branch pipe 52 on the suction circuit 40 side reaches or exceeds the second threshold pressure, the valve 54 opens and the high-pressure gas flows through the branch pipe 52 and is exhausted to the atmosphere. This keeps the pressure in the suction circuit 40 below the second threshold pressure, and therefore below the first threshold pressure, preventing damage to the suction circuit 40.

[0041] Since valve 54 opens when the pressure reaches or exceeds the second threshold pressure, strictly speaking, the pressure in suction circuit 40 may momentarily exceed the second threshold pressure by the time valve 54 opens and the high-pressure gas flows through branch pipe 52 and is exhausted to the atmosphere. Therefore, it is more preferable that the second threshold pressure is less than the first threshold pressure. In this case, the pressure in suction circuit 40 can be more reliably suppressed to or below the first threshold pressure.

[0042] The valve 54 is preferably a valve that allows gas to flow only in the direction from the branched portion 60 side of the suction pipe 44 and the branched pipe 52 to the side open to the atmosphere.

[0043] Preferably, in the branch pipe 52, the cross-sectional area of ​​the flow path 54a on the side opposite the suction circuit 40 with respect to the valve 54 (i.e., the side open to the atmosphere) is wider than the cross-sectional area of ​​the flow path 54b on the suction circuit 40 side. Note that the cross-sectional area of ​​the flow path 54a being wider than the cross-sectional area of ​​the flow path 54b means that the average cross-sectional area of ​​the flow path 54a is wider than the average cross-sectional area of ​​the flow path 54b. More preferably, the minimum cross-sectional area of ​​the flow path 54a is wider than the minimum cross-sectional area of ​​the flow path 54b. In this case, high-pressure gas easily flows to the side open to the atmosphere, so that the pressure in the suction circuit 40 can be more reliably suppressed to be equal to or lower than the first threshold pressure.

[0044] Preferably, the branch pipe 52 has a lower flow resistance than the suction pipe 44. In this case, the high-pressure gas can easily flow to the side open to the atmosphere, and the pressure in the suction circuit 40 can be more reliably suppressed to the first threshold pressure or less. Specifically, the branch pipe 52 and the suction pipe 44 are preferably configured to satisfy at least one of the following (1) to (3).

[0045] (1) The cross-sectional areas of the flow paths 54a and 54b of the branch pipe 52 are wider than the cross-sectional area of ​​the flow path 44a of the suction pipe 44. Note that the cross-sectional areas of the flow paths 54a and 54b being wider than the cross-sectional area of ​​the flow path 44a means that the average cross-sectional area of ​​the flow paths 54a and 54b is wider than the average cross-sectional area of ​​the flow path 44a. Preferably, the minimum cross-sectional area of ​​the flow paths 54a and 54b is wider than the minimum cross-sectional area of ​​the flow path 44a.

[0046] (2) The branch pipe 52 is shorter than the portion of the suction pipe 44 from the branch portion 60 to the suction pump 42. That is, the length L1 of the branch pipe 52 is shorter than the length L2 of the portion of the suction pipe 44 from the branch portion 60 to the suction pump 42.

[0047] (3) Around the branching portion 60, the angle α formed by the flow direction D1 in the suction pipe 44 on the movable mold 10 side of the branching portion 60 and the flow direction D2 in the branching pipe 52 is larger than the angle β formed by the flow direction D1 and the flow direction D3 in the suction pipe 44 on the suction pump 42 side of the branching portion 60. For example, in this embodiment, the portion of the suction pipe 44 on the movable mold 10 side of the branching portion 60 and the branching pipe 52 extend in a straight line, so the angle α is 180 degrees and the angle β is approximately 90 degrees, and therefore the angle α may be larger than the angle β.

[0048] According to the present embodiment described above, the blow molding mechanism 1 is provided with the suppression section 50, so that the pressure in the suction circuit 40 is suppressed to below the first threshold pressure, thereby preventing damage to the suction circuit 40 in the event that a hole is formed in the final molded product, the bottle container 200.

[0049] The present disclosure has been described above based on the embodiments. These embodiments are merely examples, and it will be understood by those skilled in the art that various modifications are possible in the combination of the respective components and the respective treatment processes, and that such modifications are also within the scope of the present disclosure.

[0050] (Variation 1) The suppression unit 50 is not limited to the configuration of the embodiment as long as it can suppress the pressure in the suction circuit 40 to be equal to or lower than the first threshold pressure. The suppression unit 50 may include, for example, a branch pipe 52 and a shutter provided in a portion of the suction pipe 44 closer to the suction pump 42 than the branch part 60. The shutter may block the flow path of that portion of the suction pipe 44 when the pressure in the flow path of the suction pipe 44 becomes equal to or higher than the first threshold pressure.

[0051] (Variation 2) The blow molding mechanism 1 according to the embodiment is intended to be applied to an apparatus that performs injection blow molding in two stages: injection molding and blow molding, but the blow molding mechanism 1 can also be applied to an apparatus that only performs blow molding.

[0052] (Variation 3) In the embodiment, the suction circuit 40 begins suction before the first-split mold 11 and the second-split mold 12 are opened, but this is not limiting. As long as some method can be used to maintain the orientation of the bottle container 200 when the first-split mold 11 and the second-split mold 12 are opened, the suction circuit 40 may begin suction after the first-split mold 11 and the second-split mold 12 are opened. In this case, methods for maintaining the orientation of the bottle container 200 include, for example, a method in which a suction circuit other than the suction circuit 40 (not shown) sucks a part of the bottle container 200, or a method in which the first-split mold 11, the second-split mold 12, or another member maintains the orientation of the bottle container 200.

[0053] Any combination of the above-described embodiments and modifications is also useful as an embodiment of the present disclosure. A new embodiment resulting from the combination has the combined effects of the combined embodiments and modifications. [Explanation of symbols]

[0054] 1 blow molding mechanism, 10 movable mold, 20 intermediate mold, 40 suction circuit, 42 suction pump, 44 suction pipe, 50 suppression section, 52 branch pipe, 54 valve.

Claims

1. A blow molding mechanism that blows gas into an intermediate molded product held in a mold to mold a final molded product, a suction circuit for sucking the final molded product and adhering it to the mold; a suppression unit that suppresses the pressure in the suction circuit to a predetermined value or less; Equipped with Blow molding mechanism.

2. A blow molding mechanism that blows gas into an intermediate molded product held in a mold to mold a final molded product, a suction pump that sucks the final molded product and adsorbs it to the mold; a suction pipe communicating with the suction pump and the mold; a branch pipe branching from the suction pipe; a valve provided in the branch pipe that opens when the pressure exceeds a predetermined pressure; Equipped with Blow molding mechanism.

3. The blow molding mechanism according to claim 2 , wherein the branch pipe has a flow path with a cross-sectional area on a side opposite to the branch point between the suction pipe and the branch pipe with respect to the valve, the cross-sectional area being larger than the flow path on the branch point side.

4. The blow molding mechanism according to claim 2 , wherein the branch pipe has a lower flow resistance than the suction pipe.

5. The blow molding mechanism according to claim 2 , wherein the cross-sectional area of ​​the flow path of the branch pipe is larger than the cross-sectional area of ​​the flow path of the suction pipe.

6. 3. The blow molding mechanism of claim 2, wherein the branch pipe is shorter than the portion of the suction pipe from the branch to the suction pump.

7. 3. The blow molding mechanism according to claim 2, wherein, around the branching portion, the angle formed by the flow direction of the suction pipe on the mold side of the branching portion and the flow direction of the branching pipe is larger than the angle formed by the flow direction of the suction pipe on the mold side of the branching portion and the flow direction of the suction pipe on the suction pump side of the branching portion.

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