Blow molding mechanism

Abstract

The invention provides a technology capable of reducing the risk that a suction circuit in a blow molding mechanism provided with the suction circuit is damaged. A blow molding mechanism (1) molds a final molded article by blowing a gas into an intermediate molded article held in a mold. A blow molding mechanism (1) is provided with: a suction circuit (40) that sucks a final molded article and sucks the final molded article to a mold; and a suppression unit (50) that suppresses the pressure in the suction circuit (40) to a predetermined value or less.

Description

Technical Field

[0001] This application claims priority based on Japanese Patent Application No. 2024-118870, filed on July 24, 2024. The entire contents of that Japanese application are incorporated herein by reference.

[0002] This disclosure relates to a blow molding mechanism. Background Technology

[0003] Patent document 1 discloses a blow molding process. In blow molding, gas is blown into an intermediate molded part held in a mold, causing the intermediate molded part to expand into the shape inside the mold, thereby forming a final molded part. In blow molding, a mold capable of being divided into multiple parts is used.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2022-151468

[0005] Once blow molding is complete, the parting mold is opened, and the final molded product is removed. One method for removing the final molded product from the opened parting mold is to allow it to fall freely. However, the final molded product's posture becomes unstable when the parting mold is opened, and it may sometimes come into contact with the parting mold during free fall, leaving scratches on the product.

[0006] As a countermeasure, the inventors researched the following technique: using a suction circuit to draw the final molded product and attach it to a bottom mold, thereby maintaining a stable posture of the final molded product, and then allowing the final molded product to fall freely in this state. During this research, the inventors discovered the following issues.

[0007] If a hole is formed in the final molded product due to poor molding, the high-pressure gas blown in during blow molding will enter the suction circuit through the hole, causing it to exceed the pressure limit of the suction circuit and potentially damaging the suction circuit. Summary of the Invention

[0008] This disclosure was made in view of this situation, and one of the exemplary objects of one embodiment of it is to provide a technique that can reduce the risk of damage to the suction circuit in a blow molding mechanism having a suction circuit.

[0009] To address the aforementioned issues, one embodiment of the blow molding mechanism disclosed herein is a blow molding mechanism that blows gas into an intermediate molded article held in a mold to form a final molded article. It comprises: a suction circuit for suctioning the final molded article and adhering it to the mold; and a suppression part for suppressing the pressure in the suction circuit to below a predetermined value.

[0010] Furthermore, as an embodiment of this disclosure, any combination of the above-mentioned constituent elements or the way in which the constituent elements or descriptions of this disclosure are interchanged among methods, apparatuses, systems, etc., are equally effective.

[0011] Effects of the invention: According to one embodiment of the present disclosure, the risk of damage to the suction circuit in a blow molding mechanism with a suction circuit can be reduced. Attached Figure Description

[0012] Figure 1 This is a diagram schematically illustrating the structure of the blow molding mechanism involved in the embodiment.

[0013] Figure 2 It means Figure 1 A flowchart illustrating the operation of a blow molding mechanism.

[0014] Figure 3 Figures (a) and (b) show the state of the blow molding mechanism after the blow molding process is completed.

[0015] In the diagram: 1-blow molding mechanism, 10-moving mold, 20-intermediate mold, 40-suction circuit, 42-suction pump, 44-suction pipe, 50-suppression part, 52-branch pipe, 54-valve. Detailed Implementation

[0016] The present disclosure will now be described with reference to the accompanying drawings, based on the preferred embodiments. These embodiments are illustrative and do not limit the disclosure; all features or combinations thereof described in the embodiments are not necessarily the essence of the disclosure. In the embodiments, identical or equivalent constituent elements and components are labeled with the same symbols, and repetitive descriptions are appropriately omitted.

[0017] Before detailing the embodiments of this disclosure, a general overview of the embodiments will be provided. This embodiment relates to a blow molding mechanism. The blow molding mechanism uses a blow molding circuit to blow gas into the interior of an intermediate molded article held in a mold to form a final molded article. The blow molding mechanism uses a suction circuit to suction the final molded article, causing it to adhere to the bottom mold or the like, thereby maintaining a stable posture of the final molded article, and then allowing the final molded article to fall freely in this state. This prevents the final molded article from contacting the parting mold during free fall and leaving scratches on the final molded article. Here, if a hole is formed in the final molded article due to poor molding, the high-pressure gas blown in through the blow molding circuit can enter the suction circuit through the hole, causing it to exceed the pressure resistance limit of the suction circuit and potentially damaging the suction circuit. Therefore, in this embodiment, the blow molding mechanism also includes a suppression part that suppresses the pressure in the suction circuit to below a predetermined value. As an example, the predetermined value can be either a first threshold pressure (described later) or a second threshold pressure (described later). Hereinafter, the embodiments will be described in detail.

[0018] Figure 1 This diagram schematically illustrates the structure of the blow molding mechanism 1 according to the embodiment. The blow molding mechanism 1 is applied to an injection blow molding apparatus for performing injection blow molding. Injection blow molding is a molding process in which a first stage of molding, injection molding, and a second stage of molding, blow molding, are performed consecutively. Injection molding is performed with the fixed mold and intermediate mold 20 (not shown) closed, and blow molding is performed with the moving mold 10 and intermediate mold 20 closed. The intermediate mold 20 is a so-called rotating mold disposed between the fixed mold and the moving mold 10.

[0019] In injection molding, an intermediate molded part (not shown) is formed. In blow molding, high-pressure gas (typically air) is blown into the interior of the intermediate molded part held by the passive mold 10 and the intermediate mold 20, causing the intermediate molded part to expand into the shape inside the moving mold 10, thereby forming the final molded part. The following example illustrates the case where the intermediate molded part is a preform and the final molded part is a bottle container 200.

[0020] The blow molding mechanism 1 includes a moving mold 10, an intermediate mold 20, a blow molding circuit 30, a suction circuit 40, and a suppressor 50. A horizontal sectional view from above is shown for the moving mold 10 and the intermediate mold 20. Details of the suppressor 50 will be described later.

[0021] The colored portion of the cross-section of bottle container 200 represents the stretching portion of the preform formed by blow molding. However, in reality, there is no clear distinction between the stretched and unstretched portions formed by blow molding. Therefore, Figure 1 The boundary between the colored portion and the shaded portion in the cross-section of the bottle container 200 only indicates the approximate location.

[0022] The bottle container 200 has a mouth portion 201, a main body portion 202, and a bottom portion 203. Furthermore, the mouth portion 201, the main body portion 202, and the bottom portion 203 are portions of the bottle container 200 with a continuous shape and no clearly defined boundaries. In this embodiment, the mouth portion 201 is defined as the portion near the end of the bottle container 200 on a first side in a first direction, that is, the portion including the surface 251 on the first side in the first direction of the flange 206 and the portion of the external thread 207 that engages with the internal thread of the bottle cap (not shown).

[0023] The bottom 203 is a portion formed 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 formed by the second parting mold 12, which will be described later. Specifically, the main body 202 is the portion of the bottle container 200 excluding the mouth 201 and the bottom 203.

[0024] exist Figure 1 In the middle, the moving mold 10 and the intermediate mold 20 are closed. The axial direction of the bottle container 200 in this state is... Figure 1 The left and right directions of the intermediate mold 20 and the moving mold 10 are the same as the opening and closing directions of the intermediate mold 20 and the moving mold 10. Hereinafter, the opening and closing directions of the intermediate mold 20 and the moving mold 10 will be described as follows: Figure 1 The left and right directions are referred to as the "first direction," the right side of the attached diagram in the first direction is referred to as the "first side," and the left side of the attached diagram in the first direction is referred to as the "second side." Furthermore, the direction orthogonal to the first direction (…) Figure 1 The direction above and below is called the "second direction". The upper side of the attached figure in the second direction is called the "third side". The lower side of the attached figure in the second direction is called the "fourth side".

[0025] The moving mold 10 includes a first parting mold 11, a second parting mold 12, and a bottom mold 13. The first parting mold 11 is a parting mold capable of opening and closing in a second direction. The first parting mold 11 holds the opening 201 in the closed state. Furthermore, the first parting mold 11 releases the opening 201 by opening after blow molding is completed. The first parting mold 11 is also referred to as a split mold or a parting die.

[0026] The second parting mold 12 is a parting mold capable of opening and closing in a second direction. During blow molding, the main body 202 is formed in the closed state using the second parting mold 12. Furthermore, after blow molding is completed, the main body 202 is released by opening the mold. The second parting mold 12 is also referred to as a blow molding mold.

[0027] The bottom mold 13 forms at least a portion of the bottom 203 during blow molding.

[0028] The first parting mold 11 can slide relative to the second parting mold 12 in the second direction. The second parting mold 12 can slide relative to the first parting mold 11 and the bottom mold 13 in the second direction.

[0029] The blow molding circuit 30 blows gas into the inside of the preform. The blow molding circuit 30 includes a blow molding pump 32 and a blow molding tube 34. The blow molding pump 32 blows high-pressure gas into the inside of the preform through the blow molding tube 34.

[0030] The suction circuit 40 draws gas from the bottle container 200, causing it to adhere to the moving mold 10; in this example, it adheres to the bottom mold 13. The suction circuit 40 includes a suction pump 42 and a suction tube 44, which communicates with both the pump and the inside of the moving mold 10. The bottle container 200 is drawn from the moving mold 10 by the suction pump 42 via the suction tube 44, thus adhering it to the bottom mold 13. The suction pump 42 can be a vacuum pump; that is, the suction circuit 40 can be a vacuum circuit.

[0031] Figure 2 This is a flowchart illustrating an example of the operation of the blow molding mechanism 1 after the blow molding process is completed. Figure 3 Figures (a) and (b) show the state of the blow molding mechanism 1 after the blow molding process is completed.

[0032] The suction circuit 40 initiates suction of at least a portion of the bottom 203 of the bottle container 200 (S10). Next, the mold opening between the moving mold 10 and the intermediate mold 20 begins (S12). Specifically, the moving mold 10 moves relative to the intermediate mold 20 to a second side in a first direction. The posture of the bottle container 200 at this moment is... Figure 1 The state shown is that the center line 300 of the bottle container 200 has not changed.

[0033] Next, the first parting mold 11 and the second parting mold 12 begin to open (S14). Figure 3 Figure (a) shows the state when the first parting mold 11 and the second parting mold 12 have just started to open. The first parting mold 11 and the second parting mold 12 can start to open at the same time, or the first parting mold 11 can start to open immediately after the second parting mold 12 has just started to open.

[0034] The suction circuit 40 continues to suction the bottom 203 of the bottle container 200 even when the first parting mold 11 and the second parting mold 12 begin to open. Therefore, even when the first parting mold 11 and the second parting mold 12 just begin to open, the posture of the bottle container 200 will not become unstable and will remain stable. Figure 1 The posture shown is one in which the centerline 300 of the bottle container 200 remains unchanged.

[0035] The suction force of the suction circuit 40 only needs to be sufficient to maintain the posture of the bottle container 200 when the first parting mold 11 and the second parting mold 12 begin to open; it does not need to be strong enough to support the weight of the bottle container 200 itself. Therefore, even if the suction circuit 40 continues to suction after the first parting mold 11 and the second parting mold 12 begin to open, the bottle container 200 can still fall freely using its own weight. Specifically, the bottle container 200 can fall freely along the path from... Figure 3In (b), the side perpendicular to the paper begins to fall freely towards the back side.

[0036] Next, the suction circuit 40 stops suction during the period from the start of mold opening of the first parting mold 11 and the second parting mold 12 until the mold opening is completed (S16). Furthermore, it is conceivable that because the suction force of the suction circuit 40 is strong, simply stopping suction will not immediately increase the pressure inside the suction tube 44, making it difficult for the bottle container 200 to begin to fall freely. Therefore, as a variation, a circuit for supplying air to the suction tube 44 can be connected, and after the suction of the suction circuit 40 stops, gas can be supplied to the suction tube 44 for a short time through this circuit, thereby increasing the pressure inside the suction tube 44.

[0037] As described above, the bottle container 200 is adsorbed onto the bottom mold 13 by the suction circuit 40, maintaining the bottle container 200's posture in directions other than the vertical direction (direction of gravity) even when the first parting mold 11 and the second parting mold 12 have just begun to open. Thus, the bottle container 200 begins to fall freely in a stable state where the tilting of the bottle container 200 towards the third or fourth side in the second direction from the centerline 300 is suppressed. Consequently, scratches on the bottle container 200 due to contact with the parting molds 11 and 12 are prevented.

[0038] Furthermore, if suction is not performed when the first parting mold 11 and the second parting mold 12 begin to open, a force (hereinafter referred to as "demolding force") will be generated when the first parting mold 11 and the second parting mold 12 attempt to pull the bottle container 200. The posture of the bottle container 200 may sometimes become unstable due to the demolding force. Moreover, the posture of the bottle container 200 may sometimes become unstable when it is slightly stuck on the first parting mold 11 or the second parting mold 12 during the opening of the mold. Furthermore, the posture of the bottle container 200 may sometimes become unstable due to slight vibrations caused by the opening action of the first parting mold 11 and the second parting mold 12. In any case, the posture of the bottle container 200 may sometimes become unstable. At this time, scratches may be left on the bottle container 200 due to contact with the parting molds 11 and 12.

[0039] in addition, Figure 2 The action is just one example; for instance, other steps can be added, the order of steps can be changed, or some steps can be performed simultaneously. For example, the order of S10 and S12 can be reversed. That is, the mold opening between the moving mold 10 and the intermediate mold 20 can begin before the suction circuit 40 starts suction.

[0040] However, defects in injection molding can cause holes in the intermediate molded part (pre-molded part) or in the molded part during blow molding. Alternatively, defects in blow molding can sometimes cause holes in the molded part during the blow molding process. In any case, as... Figure 1 As shown, holes 200a may be created in the final molded product, i.e., the bottle container 200. If holes are created in the bottle container 200, the high-pressure gas blown into the molded product by the blow molding circuit during blow molding may intrude into the suction circuit 40, exceeding the pressure resistance limit of the suction circuit 40 and potentially damaging it. Specifically, this could damage both the suction pump 42 and the suction pipe 44.

[0041] Therefore, as Figure 1 As shown, the blow molding mechanism 1 of the embodiment includes a suppression part 50, which suppresses the pressure in the suction circuit 40 to below a predetermined first threshold pressure.

[0042] The first threshold pressure can be determined based on the pressure resistance of the suction pump 42. For example, the first threshold pressure can be the pressure obtained by multiplying a safety factor (e.g., 0.8) by the pressure resistance of the suction pump 42. The first threshold pressure can also be determined based on the pressure resistance of the suction tube 44. For example, the first threshold pressure can be the pressure obtained by multiplying a safety factor (e.g., 0.8) by the pressure resistance of the suction tube 44. Alternatively, the first threshold pressure can also be the pressure obtained by multiplying a safety factor (e.g., 0.8) by the lower of the pressure resistance of the suction pump 42 and the pressure resistance of the suction tube 44.

[0043] In this embodiment, the suppression unit 50 includes a branch pipe 52 branching from the suction pipe 44 and a valve 54 disposed on the branch pipe 52. The branch pipe 52 is open to the atmosphere, but is not limited thereto.

[0044] Valve 54 opens when the pressure in the flow path on the suction circuit 40 side of branch pipe 52 reaches or exceeds a predetermined second threshold pressure. The second threshold pressure is below the first threshold pressure. If high-pressure gas blown into the molded part by blow molding circuit 30 enters the suction circuit 40 due to a hole in the bottle container 200, causing the pressure in the flow path of suction pipe 44 or even the flow path on the suction circuit 40 side of branch pipe 52 to reach or exceed the second threshold pressure, then valve 54 will open, and the high-pressure gas will flow through branch pipe 52 and be discharged into the atmosphere. Thus, the pressure in suction circuit 40 is maintained below the second threshold pressure, and further below the first threshold pressure, which can suppress damage to suction circuit 40.

[0045] Furthermore, since valve 54 is a valve that opens when the pressure reaches or exceeds the second threshold pressure, strictly speaking, until valve 54 opens and the high-pressure gas flows through branch pipe 52 and is discharged into the atmosphere, the pressure within the suction circuit 40 may momentarily exceed the second threshold pressure. Therefore, it is more preferable that the second threshold pressure is less than the first threshold pressure. In this case, the pressure within the suction circuit 40 can be more reliably suppressed below the first threshold pressure.

[0046] Valve 54 is preferably a valve that allows gas to flow only along the direction from the branch 60 side of the suction pipe 44 and the branch pipe 52 toward the open side of the atmosphere.

[0047] Preferably, in branch pipe 52, the cross-sectional area of ​​flow path 54a on the side opposite to valve 54 and suction circuit 40 (i.e., the atmospheric open side) is larger than the cross-sectional area of ​​flow path 54b on the suction circuit 40 side. Furthermore, the fact that the cross-sectional area of ​​flow path 54a is larger than that of flow path 54b indicates that the average cross-sectional area of ​​flow path 54a is larger than the average cross-sectional area of ​​flow path 54b. More preferably, the minimum cross-sectional area of ​​flow path 54a is larger than the minimum cross-sectional area of ​​flow path 54b. In this case, high-pressure gas tends to flow towards the atmospheric open side, thus more reliably suppressing the pressure within suction circuit 40 below the first threshold pressure.

[0048] Preferably, the flow resistance of the branch pipe 52 is lower than that of the suction pipe 44. In this case, the high-pressure gas can easily flow to the open side of the atmosphere, thus more reliably suppressing the pressure in the suction circuit 40 below the first threshold pressure. Specifically, preferably, the branch pipe 52 and the suction pipe 44 are configured to satisfy at least one of the following (1) to (3).

[0049] (1) The cross-sectional areas of flow paths 54a and 54b in branch pipe 52 are larger than the cross-sectional area of ​​flow path 44a in suction pipe 44. Furthermore, the fact that the cross-sectional areas of flow paths 54a and 54b are larger than the cross-sectional area of ​​flow path 44a indicates that the average cross-sectional area of ​​flow paths 54a and 54b is greater than the average cross-sectional area of ​​flow path 44a. Preferably, the minimum cross-sectional area of ​​flow paths 54a and 54b is greater than the minimum cross-sectional area of ​​flow path 44a.

[0050] (2) The branch pipe 52 is shorter than the portion from the branch 60 to the suction pipe 44 of the suction pump 42. That is, the length L1 of the branch pipe 52 is shorter than the length L2 of the portion from the branch 60 to the suction pipe 44 of the suction pump 42.

[0051] (3) Around the branch 60, the angle α formed by the flow direction D1 in the suction pipe 44 closer to the moving mold 10 than the branch 60 and the flow direction D2 in the branch pipe 52 is greater than the angle β formed by the flow direction D1 and the flow direction D3 in the suction pipe 44 closer to the suction pump 42 than the branch 60. For example, in this embodiment, the portion of the suction pipe 44 closer to the moving mold 10 than the branch 60 and the branch pipe 52 extend in a straight line, so the angle α is 180 degrees and the angle β is approximately 90 degrees. Therefore, the angle α can be greater than the angle β.

[0052] According to the embodiment described above, by having a suppression part 50 in the blow molding mechanism 1, the pressure in the suction circuit 40 can be suppressed below a first threshold pressure, thereby suppressing the damage to the suction circuit 40 when a hole is formed on the final molded product, i.e., the bottle container 200.

[0053] The present disclosure has been described above based on the embodiments. These embodiments are examples, and those skilled in the art will understand that various modifications can exist in the combination of these constituent elements or processing steps, and such modifications are also included within the scope of the present disclosure.

[0054] (Variation Example 1)

[0055] The suppression unit 50 is only required to suppress the pressure within the suction circuit 40 below the first threshold pressure, and is not limited to the structure of the embodiment. The suppression unit 50 may, for example, include a branch pipe 52 and an opening / closing plate disposed on a portion of the suction pipe 44 located closer to the suction pump 42 than the branch section 60. The opening / closing plate can cut off the flow path of that portion of the suction pipe 44 when the pressure within the flow path of the suction pipe 44 exceeds the first threshold pressure.

[0056] (Variation Example 2)

[0057] The blow molding mechanism 1 described in the embodiment is intended for use in an injection blow molding apparatus that performs injection molding and blow molding in two stages, but the blow molding mechanism 1 can also be used in an apparatus that performs only blow molding.

[0058] (Variation Example 3)

[0059] In this embodiment, the suction circuit 40 begins suction before the first parting mold 11 and the second parting mold 12 are opened, but it is not limited to this. As long as some method can be used to maintain the posture of the bottle container 200 when the first parting mold 11 and the second parting mold 12 are opened, the suction circuit 40 can also begin suction after the first parting mold 11 and the second parting mold 12 are opened. In this case, as a method for maintaining the posture of the bottle container 200, examples include methods such as using other suction circuits (not shown) other than the suction circuit 40 to suction a portion of the bottle container 200, or methods where the posture of the bottle container 200 is maintained by the first parting mold 11, the second parting mold 12, or other components.

[0060] As embodiments of this disclosure, any combination of the above embodiments and modifications is equally effective. New embodiments resulting from such combinations possess the effects of both the combined embodiments and modifications.

Claims

1. A blow molding mechanism that blows gas into an intermediate molded article held in a mold to form a final molded article, said blow molding mechanism comprising: The suction circuit draws the final molded article into the mold, causing it to adhere to the mold; and The suppression unit suppresses the pressure within the suction circuit to below a specified value.

2. A blow molding mechanism that blows gas into an intermediate molded article held in a mold to form a final molded article, said blow molding mechanism comprising: A suction pump is used to draw the final molded article and cause it to adhere to the mold. A suction tube is connected to the suction pump and the mold; Branch tube, branching from the suction tube; and A valve is provided on the branch pipe and opens when the pressure reaches a specified level.

3. The blow molding mechanism according to claim 2, wherein, In the branch pipe, the cross-sectional area of ​​the flow path on the side opposite to the valve, the suction pipe, and the branch portion of the branch pipe is larger than the cross-sectional area of ​​the flow path on the branch portion side.

4. The blow molding mechanism according to claim 2, wherein, The flow resistance of the branch pipe is lower than that of 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. The blow molding mechanism according to claim 2, wherein, The branch pipe is shorter than the portion of the suction pipe from the branch to the suction pump.

7. The blow molding mechanism according to claim 2, wherein, Around the branch, the angle between the flow direction of the suction pipe closer to the mold side than the branch and the flow direction of the branch pipe is greater than the angle between the flow direction of the suction pipe closer to the mold side than the branch and the flow direction of the suction pipe closer to the suction pump side than the branch.

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