Inflation forming apparatus, and guiding device

Abstract

To generate a sufficient negative pressure between a bubble formed during inflation forming, and a guide plate that attracts the bubble so as to stabilize a shape of the bubble.SOLUTION: In an inflation forming apparatus 1, a plurality of guide plates for guiding a flow of air passing through an outer surface side of a bubble 200 are arranged to form layers. In a second guide plate 12 which forms an outer layer of a first guide plate 11 which forms the inner most layer, a first through hole 121 is formed which penetrates the second guide plate in a radial direction at a position on the upper side of the center 111 of the first guide plate 11 in a vertical direction. In a third guide plate 13 which forms an outer layer of the second guide plate 12, a second through hole 131 and a third through hole 132 are formed which penetrate the third guide plate in the radial direction at positions on the lower side and the upper side, respectively, of the center 123 of the second guide plate 12 in the vertical direction.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an inflation molding apparatus and an induction device. [Background technology]

[0002] A blown film molding technique is known in which air is sent toward molten resin extruded into a cylindrical shape to form a film product (see, for example, Patent Document 1). In blown film molding, air is sent toward the inner surface of molten resin extruded into a cylindrical shape, causing it to expand, creating a thin cylindrical bubble, and the film product is formed by applying air to the outer surface of the bubble to cool it. A cylindrical guide plate is arranged outside the bubble to guide the air that is sent out. This guide plate guides the air that is sent toward the bubble. Negative pressure is generated between the bubble and the guide plate as the air passes, so the bubble is attracted to the guide plate. The guide plate stabilizes the shape of the bubble by maintaining a sufficiently attracted state of the bubble. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-156852 Summary of the Invention [Problem to be solved by the invention]

[0004] In order to sufficiently attract the bubbles to the guide plate, a sufficient negative pressure must be generated between the bubbles and the guide plate. An object of the present invention is to generate a sufficient negative pressure between a bubble formed during inflation molding and a guide plate that attracts the bubble to stabilize its shape. [Means for solving the problem]

[0005] The present invention, which was completed with this objective in mind, is an inflation molding apparatus characterized in that guide plates, which are cylindrical plates that guide the flow of air passing through the outer side of the bubbles, are arranged to form multiple layers on the outer side of bubbles formed by blowing air into the inner side of molten resin extruded into a cylindrical shape, and of the guide plates that form the multiple layers, a second guide plate that forms the outer layer of a first guide plate that forms the innermost layer has a first through hole formed in it that passes radially through a position above the center of the first guide plate in the vertical direction, and a third through hole that passes radially through a position below and above the center of the second guide plate in the vertical direction, respectively. Here, a fourth through hole may be further formed to penetrate the second guide plate in the radial direction at a position on the upper side of the tip end of the second guide plate in the vertical direction. The second through hole may be disposed on the upper side of the first through hole in the vertical direction. At least one of the first to fourth through holes may be opened and closed. Furthermore, a sixth through hole and a seventh through hole may be formed in a fourth guide plate that forms an outer layer of the third guide plate, and the sixth through hole and the seventh through hole may be formed radially through positions on the ground side and the top side of the center of the third guide plate in the vertical direction. The sixth through hole may be disposed on the upper side of the second through hole in the vertical direction. The seventh through hole may be disposed on the upward side of the third through hole in the vertical direction. The fourth guide plate may further be formed with an eighth through hole that passes through in the radial direction at a position on the top side of the seventh through hole in the vertical direction. The eighth through hole may be disposed on the upper side of the fourth through hole in the vertical direction. At least one of the sixth to eighth through holes may be opened and closed. The present invention also provides an induction device characterized in that guide plates, which are cylindrical plates that guide the flow of air passing through the outer side of bubbles formed by blowing air into the inner side of molten resin extruded into a cylindrical shape, are arranged to form multiple layers on the outer side of the bubbles, and of the guide plates that form the multiple layers, a second guide plate that forms the outer layer of a first guide plate that forms the innermost layer has a first through hole that penetrates radially to a position above the vertical position of the center of the first guide plate, and a third through hole that penetrates radially to a position below and above the vertical position of the center of the second guide plate, respectively. [Effects of the Invention]

[0006] According to the present invention, a sufficient negative pressure can be generated between the bubble formed during inflation molding and the guide plate that attracts the bubble to stabilize the bubble shape. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a diagram showing an example of the configuration of an inflation molding apparatus according to a first embodiment. [Figure 2] 3 is a diagram showing an example of a configuration of a plurality of through holes formed in a guide plate constituting the guide device according to the first embodiment; FIG. [Figure 3] 10A and 10B are diagrams showing specific examples of through holes formed in a guide plate. [Figure 4] 10A and 10B are diagrams illustrating an example of a configuration of a plurality of through holes formed in a guide plate constituting the guide device according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. First Embodiment (Configuration of inflation molding device) FIG. 1 is a diagram showing an example of the configuration of an inflation molding apparatus 1 according to the first embodiment. The inflation molding apparatus 1 shown in FIG. 1 is an apparatus for molding a resin film as a product by inflation molding. The inflation molding apparatus 1 heats the resin that will be the material for the film product to make it molten, extrudes the molten resin from an annular die 31, which is a nozzle, and blows air 600 into the inner surface of the cylindrical molten resin. This causes the molten resin to expand, forming a bubble 200 of molten resin in the shape of a thin cylinder. The inflation molding apparatus 1 blows air 610, which acts as cooling air, onto the outer surface of the formed bubble 200, solidifying the bubble 200. This results in the molding of a resin film 530 as a product.

[0009] The up-down direction in FIG. 1 is the top-to-bottom direction and indicates the axial direction of the bubble 200. The bubble 200 formed during inflation molding by the inflation molding apparatus 1 is cooled and gradually solidified as it is fed from the bottom side to the top side in the top-to-bottom direction. For this reason, the bottom side of the bubble 200 shown in FIG. 1 is closer to the die 31 and has a higher temperature than the top side in the top-to-bottom direction. In other words, the state of the bubble 200 shown in FIG. 1 is a state in the middle of molding where the bubble is gradually solidifying, although it has not yet reached the state of the film 530 as a product.

[0010] 1 indicates the radial direction of bubble 200. Hereinafter, the side of bubble 200 closer to central axis 300 is referred to as the radially inner side, and the side farther from central axis 300 is referred to as the radially outer side. Frost line 400 extending in the radial direction of bubble 200 is a portion where transparency changes as the molten resin cools and solidifies, and can be regarded as the approximate boundary line where bubble 200 in a molten state cools and solidifies to become film 530.

[0011] The inflation molding apparatus 1 includes an induction device 10 that induces a flow of air 610 that cools and solidifies the bubbles 200. The induction device 10 includes a first induction plate 11, a second induction plate 12, and a third induction plate 13, which are cylindrical plates that induce the flow of air 610. The first induction plate 11, the second induction plate 12, and the third induction plate 13 form layers. Of the three layers of induction plates, the first induction plate 11 is the radially innermost guide plate and is arranged around the air outlet 21 that blows out the air 610. The second guide plate 12 is arranged to surround the first guide plate 11. The third guide plate 13 is the radially outermost guide plate of the three layers of induction plates and is arranged around the second guide plate 12. The thickness of each of the three layers of guide plates is not particularly limited, but for example, if the diameter of the guide plate is approximately 300 mm (millimeters), the thickness is approximately 5 mm (millimeters) to 10 mm (millimeters).

[0012] The top and bottom positions of the tips of the three guide plates are configured so that the top and bottom position of tip 120 of second guide plate 12 is located higher than the top and bottom position of tip 110 of first guide plate 11. Also, the top and bottom position of tip 130 of third guide plate 13 is located higher than the top and bottom position of tip 120 of second guide plate 12.

[0013] The radially inner surface of each of the three guide plates is the surface facing bubble 200 (hereinafter referred to as the "facing surface"). Air 610 passing between bubble 200 and the facing surface of the guide plate generates negative pressure between bubble 200 and the facing surface of the guide plate. In other words, the air pressure in the space formed between bubble 200 and the facing surface of the guide plate is lower than the air pressure in the space formed by air 600 being sent to the inner side of bubble 200 (a state in which negative pressure is generated).

[0014] In particular, the area between the bubble 200 and each of the opposing surfaces of the three guide plates is a region where air 610 from the air outlet 21 and air outside the inflation molding apparatus 1 (hereinafter simply referred to as "outside air" or "air from outside") that has been drawn into the air 610 converge, making negative pressure likely to occur. In this region where negative pressure is likely to occur, the bubble 200 is attracted to the guide plates, and the distance between the bubble 200 and the tip of each guide plate may become as close as about 5 mm (millimeters), for example. However, because contact between the bubble 200 and the guide plates may cause the bubble 200 to break, the negative pressure is controlled to a level that prevents the bubble 200 from coming into contact with the guide plates.

[0015] The inflation molding apparatus 1 controls the position of the bubble 200 by controlling the negative pressure generated near the opposing surfaces of the three guide plates. Specifically, the inflation molding apparatus 1 attracts the bubble 200 to the first guide plate 11, the second guide plate 12, and the third guide plate 13 by controlling the negative pressure generated in the spaces formed between the bubble 200 and the opposing surfaces of the first guide plate 11, the second guide plate 12, and the third guide plate 13. In this way, the shape of the bubble 200 is stabilized.

[0016] In this embodiment, the negative pressure generated near the opposing surface of the guide plate is controlled by controlling the flow of air passing through a plurality of through-holes that penetrate the guide plate in the radial direction. These through-holes will be described with reference to Figure 2, which is an enlarged view of the area enclosed by the dashed line in Figure 1.

[0017] (Through-hole configuration) FIG. 2 is a diagram showing an example of the configuration of a plurality of through holes formed in a guide plate constituting the guide device 10 according to the first embodiment. Of the first guide plate 11, second guide plate 12, and third guide plate 13, which each form a layer, the second guide plate 12, which forms the outer layer of the first guide plate 11, has a first through hole 121 formed therein that penetrates the second guide plate 12 in the radial direction. The first through hole 121 is a through hole that is positioned on the upper side of the center portion 111 of the first guide plate 11 in the vertical direction.

[0018] The third guide plate 13, which forms an outer layer of the second guide plate 12, is formed with a second through hole 131, a third through hole 132, and a fourth through hole 133 penetrating the third guide plate 13 in the radial direction. The second through hole 131 is a through hole positioned closer to the bottom than the center 123 of the second guide plate 12 in the vertical direction. The third through hole 132 is a through hole positioned closer to the top than the center 123 of the second guide plate 12 in the vertical direction. The fourth through hole 133 is a through hole positioned closer to the top than the tip 120 of the second guide plate 12 in the vertical direction. The first guide plate 11, which forms an inner layer of the second guide plate 12, is also formed with a fifth through hole 112 penetrating the first guide plate 11 in the radial direction. The fifth through hole 112 may or may not be formed in the first guide plate 11. For example, when the first guide plate 11 is close to the air outlet 21, there is little need to pass the air 620 through the fifth through hole 112 and have it drawn into the air 610, so it is not necessary to form the fifth through hole 112 in the first guide plate 11.

[0019] The first through hole 121 formed in the second guide plate 12, the second through hole 131, the third through hole 132, and the fourth through hole 133 formed in the third guide plate 13, and the fifth through hole 112 formed in the first guide plate 11 are all through holes for allowing air from the outside to pass radially inward. The air from the outside moves from the outside to the inside in the radial direction, being caught up in the air 610 from the air outlet 21. Some of the air from the outside moving radially inward strikes the radially outer surface of the third guide plate 13 and is divided into two parts, one moving toward the top side and the other moving toward the bottom side. Some of the air from the outside passes through the top side of the tip 130 of the third guide plate 13.

[0020] A portion of the air from outside that hits the radially outer surface of third guide plate 13 passes through second through-hole 131 of third guide plate 13 and first through-hole 121 of second guide plate 12, and merges with air 610 from air outlet 21. FIG. 2 shows region 701 where air 621 from outside that has passed through second through-hole 131 and first through-hole 121 merges with air 610 from air outlet 21. Sufficient negative pressure is generated in region 701, so that bubbles 200 can be attracted to the opposing surface of second guide plate 12. Note that region 701 indicated by a dashed line in FIG. 2 is an approximate position, and negative pressure may also occur outside the region indicated by the dashed line.

[0021] A portion of the air from the outside that hits the radially outer surface of third guide plate 13 passes through third through-hole 132 and merges with air 610 from air outlet 21. A portion of the air from the outside that hits the radially outer surface of third guide plate 13 passes through fourth through-hole 133 and merges with air 610 from air outlet 21. A portion of the air from the outside that passes through the top side of tip end 130 of third guide plate 13 in the vertical direction merges with air 610 from air outlet 21.

[0022] Here, it is desirable to form a through hole in the outer guide plate at a position closer to the ground than the top end of the inner guide plate, thereby forming a region where negative pressure is generated in an area that is closer to the top than the top end of the inner guide plate and closer to the ground than the top end of the outer guide plate. However, a through hole may also be added closer to the top than the top end of the inner guide plate.

[0023] 2, when the inner guide plate is the first guide plate 11 and the outer guide plate is the second guide plate 12, the position of the first through hole 121 in the vertical direction is located between the tip 110 on the top side and the center 111 of the first guide plate 11. This allows a region 701 that generates negative pressure to be formed in the region on the bottom side of the tip 120 on the top side of the second guide plate 12.

[0024] Furthermore, when the inner guide plate is the second guide plate 12 and the outer guide plate is the third guide plate 13, the position of the third through hole 132 in the vertical direction is located between the tip 120 on the top side of the second guide plate 12 and the center 123. This allows a region 702 that generates negative pressure to be formed in a region including a region on the bottom side of the tip 130 on the top side of the third guide plate 13.

[0025] Furthermore, a through hole may be added to the outer guide plate at a position higher than the top end of the inner guide plate. Fig. 2 shows an example in which a fourth through hole 133 is added to the outer third guide plate 13 at a position higher than the top end 120 of the inner second guide plate 12. However, when the fourth through hole 133 is added as in the example of Fig. 2, it is preferable that the flow rate of air passing through the third through hole 132, which is located lower than the top end 120 of the second guide plate 12, is greater than the flow rate of air passing through the fourth through hole 133.

[0026] 2 shows a region 702 where air 622 from outside that has passed through third through-hole 132, air 623 from outside that has passed through fourth through-hole 133, and air 624 from outside that has passed through the top side of tip 130 of third guide plate 13 join air 610 from air outlet 21. In region 702, sufficient negative pressure is generated, so bubbles 200 can be attracted to the opposing surface of third guide plate 13. Note that region 702 shown by a dashed line in FIG. 2 is an approximate position, and negative pressure can also occur outside the region shown by the dashed line.

[0027] The positions of the first through hole 121 formed in the second guide plate 12 and the second through hole 131, the third through hole 132, and the fourth through hole 133 formed in the third guide plate 13 are important factors that determine the magnitude of the negative pressure generated in each of the regions 701 and 702. In this embodiment, the positions of the first through hole 121, the second through hole 131, the third through hole 132, and the fourth through hole 133 are changeable. Note that the method for changing the positions of the first through hole 121, the second through hole 131, the third through hole 132, and the fourth through hole 133 is not particularly limited. For example, a shutter mechanism may be provided for each of a large number of through holes formed in advance at various positions on the guide plate, and the opening and closing of each through hole may be controlled, thereby changing the positions of the through holes according to the pattern of the positions of the open and closed through holes. 2, the open through holes are first through hole 121, second through hole 131, third through hole 132, and fourth through hole 133, and closed through holes are not shown. Alternatively, multiple types of guide plates with different patterns of through hole position may be prepared, and the positions of the through holes may be changed by installing guide plates according to the shape of the bubble and molding conditions.

[0028] When the opening and closing of each through-hole can be controlled, for example, a pressure sensor can be installed near the area where negative pressure is generated, and the opening and closing of each through-hole can be controlled so that the measurement value of the pressure sensor becomes the intended value. In this case, the pressure sensor can be installed at the tip of each guide plate, for example. Furthermore, when a pressure sensor is not installed, the opening and closing of each through-hole can be controlled so that the stability of the bubble shape, which is measured separately, becomes the intended value. The stability of the bubble shape is measured, for example, by a distance sensor that measures the distance between a predetermined position and the bubble 200.

[0029] Furthermore, if the shape of the bubbles 200 formed during molding can be determined from the combination of the type of resin used to make the film product and the molding conditions, the opening and closing patterns of each through hole may be associated in advance with each combination of the type of resin and the molding conditions. In this case, by selecting the opening and closing pattern of each through hole according to the combination of the type of resin and the molding conditions, it is possible to generate a negative pressure of the intended magnitude in the intended area.

[0030] Furthermore, for example, if each through-hole is composed of a group of small through-holes as shown in Fig. 3 (described later) and the opening and closing of each of the small through-holes in the group can be controlled, it is possible to generate a negative pressure of a desired magnitude in a desired region with a more precise level, which makes it possible to locally adjust the film thickness of the bubble 200.

[0031] In this way, the guiding device 10 is capable of changing the positions of the first through hole 121, the second through hole 131, the third through hole 132, and the fourth through hole 133, and is therefore adaptable to various shapes and molding conditions of the bubble 200. As a result, the versatility of the guiding device 10 can be improved, which reduces the need to prepare a dedicated guide plate each time that fits the shape of the bubble 200, which is determined depending on, for example, the type of resin used as the material, the molding conditions, etc.

[0032] 2 are merely examples showing the positions of four through holes, among the many through holes provided in each of the second guide plate 12 and the third guide plate 13, that are opened according to the shape of the bubble 200 and molding conditions. For example, the position of the first through hole 121 formed in the second guide plate 12 is merely an example, and the first through hole 121 may be formed in another position. Furthermore, although the second guide plate 12 has one through hole formed therein, it may have two or more through holes formed therein, or the second guide plate 12 may have no through hole formed therein.

[0033] Similarly, the positions of the second through hole 131, the third through hole 132, and the fourth through hole 133 formed in the third guide plate 13 are also examples, and each may be formed in another position. Furthermore, although the third guide plate 13 has three through holes formed therein, the third guide plate 13 may have four or more through holes formed therein, or may have one or two through holes formed therein. Furthermore, the third guide plate 13 may not have any through holes formed therein. Furthermore, the first guide plate 11 shown in FIG. 2 has the fifth through hole 112 formed therein, but as described above, the fifth through hole 112 may not be formed therein. Furthermore, the first guide plate 11 may have through holes formed in multiple positions.

[0034] 2, first through-holes 121 formed in second guide plate 12 are arranged at positions that make it easy for air 621 from the outside to efficiently merge with air 610 from air outlet 21. Specifically, first through-holes 121 are arranged to be located higher than the position of center 111 of first guide plate 11 in the vertical direction. Therefore, compared to when first through-holes 121 are arranged to be located lower than the position of center 111 of first guide plate 11 in the vertical direction, air 621 from the outside that has passed through first through-hole 121 can be smoothly merged with air 610 from air outlet 21 without being retained in the space between first guide plate 11 and second guide plate 12.

[0035] 2, the second through-holes 131 formed in the third guide plate 13 are disposed at positions that make it easy to send the air 621 from the outside toward the first through-holes 121. Specifically, the second through-holes 131 are disposed so as to be located closer to the ground than the center 123 of the second guide plate 12 in the vertical direction. Therefore, compared to when the second through-holes 131 are disposed so as to be located closer to the top than the center 123 of the second guide plate 12 in the vertical direction, the air 621 from the outside that has moved downward toward the ground side of the third guide plate 13 in the vertical direction can be efficiently taken inward in the radial direction.

[0036] 2, the positional relationship between the first through-holes 121 formed in the second guide plate 12 and the second through-holes 131 formed in the third guide plate 13 is such that air 621 from the outside is efficiently taken inward in the radial direction and easily merges with air 610 from the air outlet 21. Specifically, the second through-holes 131 are configured to be located higher than the position of the first through-holes 121 in the vertical direction. This allows the flow of air 621 from the outside that hits the third guide plate 13 and moves downward toward the ground in the vertical direction to pass through the second through-holes 131 and the first through-holes 121.

[0037] 2, the third through-holes 132 formed in the third guide plate 13 are positioned to facilitate efficient confluence of the air 622 from the outside with the air 610 from the air outlet 21. Specifically, the third through-holes 132 are positioned higher than the center 123 of the second guide plate 12 in the vertical direction. Therefore, compared to when the third through-holes 132 are positioned lower than the center 123 of the second guide plate 12 in the vertical direction, the air 622 from the outside that has passed through the third through-holes 132 can be smoothly confluent with the air 610 from the air outlet 21 without being retained in the space between the second guide plate 12 and the third guide plate 13.

[0038] 2, the fourth through hole 133 formed in the third guide plate 13 is positioned so as to facilitate efficient confluence of air 623 from the outside with air 610 from the air outlet 21. Specifically, the fourth through hole 133 is positioned higher than the vertical position of the tip end 120 of the second guide plate 12. The fourth through hole 133 is an additional through hole that is provided depending on the negative pressure situation, such as when the third through hole 132 alone is not effective in generating negative pressure.

[0039] (Example of through holes) FIG. 3 is a diagram showing a specific example of a through hole formed in the guide plate. The four through holes (first through hole 121 to fourth through hole 133) formed in first guide plate 11, second guide plate 12, and third guide plate 13 shown in Fig. 2 above are each drawn as a single through hole, but this is a simplification to make it easier to understand the general positions where the through holes are formed in the guide plates and the flow of air from the outside. Therefore, the number, size, and exact positions of the through holes drawn in Fig. 2 are not limited to the example of Fig. 2. For example, the through holes formed in first guide plate 11, second guide plate 12, and third guide plate 13 may be formed one at a time or multiple at a time.

[0040] 3 shows an example of a case where a plurality of small through holes 122 are formed, as a specific example of the configuration of first through holes 121 formed in second guide plate 12 of FIG. 2 described above. First through holes 121 shown in FIG. 3 are a group of small through holes 122 formed in the circumferential direction of second guide plate 12. This configuration of first through holes 121 allows air from the outside to be evenly taken inward in the radial direction to join air 610 from air outlet 21 passing through the outer surface side of bubble 200, thereby making the film thickness of bubble 200 uniform.

[0041] In summary, the inflation molding apparatus 1 according to the first embodiment of the present invention only needs to have the following configuration, and can take on a variety of different embodiments. That is, the inflation molding apparatus 1 is characterized in that a first guide plate 11, a second guide plate 12, and a third guide plate 13, which are cylindrical plates that guide the flow of air 610 passing through the outer side of the bubble 200, are arranged to form layers on the outer side of the bubble 200 by sending air 600 into the inner side of the molten resin extruded into a cylindrical shape, and of the first guide plate 11, the second guide plate 12, and the third guide plate 13 that form layers, the second guide plate 12, which forms the outer layer of the first guide plate 11 that forms the innermost layer, is formed with a first through hole 121 that radially penetrates to a position above the center 111 of the first guide plate 11 in the vertical direction, and a second through hole 131 and a third through hole 132 that radially penetrate to positions below and above the center 123 of the second guide plate 12 in the vertical direction, respectively.

[0042] As a result, of the three-layer guide plates that guide the flow of air 610 passing through the outer surface side of bubble 200, first through-hole 121 formed in second guide plate 12 and second through-hole 131 and third through-hole 132 formed in third guide plate 13 allow air 621 to 624 from the outside to pass radially inward from the outside and merge with air 610 from air outlet 21. A sufficient negative pressure is generated in the region where air 610 from air outlet 21 and air 621 to 624 from the outside merge, so that bubble 200 can be drawn toward the guide plate.

[0043] Here, a fourth through hole 133 may be further formed to penetrate the second guide plate 12 in the radial direction at a position on the upper side of the top end portion 120 of the second guide plate 12 in the vertical direction. As a result, the fourth through-holes 133 allow air 623 from the outside to pass from the outside to the inside in the radial direction and join air 610 from the air outlet 21. Since a sufficient negative pressure is generated in the area where the air from the air outlet joins the air from the outside, bubbles can be attracted to the guide plate.

[0044] Here, the second through hole 131 formed in the third guide plate 13 may be characterized in that it is positioned on the upper side of the first through hole 121 formed in the second guide plate 12 in the vertical direction. This makes it easier to send the air 621 from the outside that has passed through the second through-holes 131 toward the first through-holes 121.

[0045] Furthermore, at least one of the first through hole 121, the second through hole 131, the third through hole 132, and the fourth through hole 133 may be characterized in that it opens and closes. The guide plate arranged outside the bubble 200 is preferably a dedicated one that conforms to the bubble shape, which is determined by the type of resin used to make the film, molding conditions, and the like. However, in inflation molding, where a wide variety of moldings are performed, it is difficult to prepare guide plates that conform to each of the diverse bubble shapes. In contrast, because at least one of the first through hole 121, the second through hole 131, the third through hole 132, and the fourth through hole 133 opens and closes, it is possible to control the negative pressure generated in the area where the air 610 from the air outlet 21 and the air 621-624 from the outside join. As a result, the guide plate can be made more versatile than if dedicated guide plates were prepared each time to conform to each of the diverse bubble 200 shapes.

[0046] <Second embodiment> FIG. 4 is a diagram showing an example of the configuration of a plurality of through holes formed in a guide plate constituting the guide device 20 according to the second embodiment. The inflation molding apparatus 2 shown in Fig. 4 has the same configuration as the inflation molding apparatus 1 shown in Fig. 2, except that it has one more layer of guide plates. That is, the guide device 10 of the inflation molding apparatus 1 shown in Fig. 2 is composed of three layers of guide plates, whereas the guide device 20 of the inflation molding apparatus 2 shown in Fig. 4 is composed of four layers of guide plates.

[0047] Of the four layers of guide plates, the fourth guide plate 14, which forms the outer layer of the third guide plate 13, has a sixth through hole 141, a seventh through hole 142, and an eighth through hole 143 formed in it. The sixth through hole 141 is a through hole that passes through the third guide plate 13 in the radial direction at a position further down than the vertical position of the center 134 of the third guide plate 13. The seventh through hole 142 is a through hole that passes through the third guide plate 13 in the radial direction at a position further up than the vertical position of the center 134 of the third guide plate 13. The eighth through hole 143 is a through hole that passes through the radial direction at a position further up than the vertical position of the seventh through hole 142.

[0048] The sixth through hole 141, the seventh through hole 142, and the eighth through hole 143 formed in the fourth guide plate 14 are through holes for passing air from outside, similar to the first through hole 121 formed in the second guide plate 12 and the second through hole 131, the third through hole 132, and the fourth through hole 133 formed in the third guide plate 13. Some of the air from outside hits the radially outer surface of the fourth guide plate 14 and is divided into two parts, one moving toward the top side in the vertical direction and the other moving toward the bottom side. Some of the air from outside also passes through the top side of the tip 140 of the fourth guide plate 14 in the vertical direction.

[0049] A portion of the air from outside that strikes the radially outer surface of the fourth guide plate 14 passes through the sixth through-hole 141 of the fourth guide plate 14, the second through-hole 131 of the third guide plate 13, and the first through-hole 121 of the second guide plate 12, and merges with the air 610 from the air outlet 21. FIG. 4 shows a region 701 where the air 625 from outside merges with the air 610 from the air outlet 21 as the air 621 from outside that has passed through the sixth through-hole 141, the second through-hole 131, and the first through-hole 121. A sufficient negative pressure is generated in the region 701, allowing the bubbles 200 to be attracted to the opposing surface of the second guide plate 12. Note that the region 701 indicated by the dashed line in FIG. 4 is an approximate location, and negative pressure may also occur outside the region indicated by the dashed line.

[0050] A portion of the air from outside that hits the radially outer surface of the fourth guide plate 14 passes through the seventh through hole 142 and the third through hole 132 or the fourth through hole 133, and merges with the air 610 from the air outlet 21. A portion of the air from outside that hits the radially outer surface of the fourth guide plate 14 passes through the eighth through hole 143. A portion of the air from outside that has passed through the eighth through hole 143 merges with the air 610 from the air outlet 21. A portion of the air from outside that has passed through the eighth through hole 143 further passes through the fourth through hole 133 and merges with the air 610 from the air outlet 21. A portion of the air from outside that has passed through the eighth through hole 143 passes through the top side of the tip portion 130 of the third guide plate 13 in the vertical direction, and merges with the air 610 from the air outlet 21. Furthermore, part of the air from the outside that has passed through the top side of the tip 140 of the fourth guide plate 14 joins with the air 610 from the air outlet 21 .

[0051] 4 shows a region 702 where air from the outside joins with air 610 from the air outlet 21. The region 702 is a region where air 626 from the outside joins with air 610 from the air outlet 21 as air 622 from the outside that has passed through the seventh through hole 142 and the third through hole 132. The region 702 is also a region where air 626 from the outside joins with air 610 from the air outlet 21 as air 623 from the outside that has passed through the seventh through hole 142 and the fourth through hole 133. The region 702 is also a region where air 627 from the outside joins with air 610 from the air outlet 21 as air 623 from the outside that has passed through the eighth through hole 143 and the fourth through hole 133. Region 702 is also a region where air 627 from outside passes through eighth through-hole 143, passes through the top side of tip 130 of third guide plate 13 in the vertical direction, and merges with air 610 from air outlet 21 as air 624 from outside. Sufficient negative pressure is generated in region 702, so bubbles 200 can be attracted to the opposing surface of third guide plate 13. Note that region 702 indicated by the dashed line in FIG. 4 indicates an approximate position, and negative pressure can also occur outside the region indicated by the dashed line.

[0052] FIG. 4 also shows region 703 where air from outside joins air 610 from air outlet 21. Region 703 is the region where air 627 from outside passes through eighth through-hole 143 and joins air 610 from air outlet 21 as air from outside 624. Region 703 is also the region where air 628 from outside that has passed through the top side of tip 140 of fourth guide plate 14 joins air 610 from air outlet 21. Sufficient negative pressure is generated in region 703, so that bubbles 200 can be attracted to the opposing surface of fourth guide plate 14. Note that region 703 shown by the dashed line in FIG. 4 is an approximate position, and negative pressure can also occur outside the region shown by the dashed line.

[0053] The positions of the sixth through hole 141, the seventh through hole 142, and the eighth through hole 143 formed in the fourth guide plate 14 are important factors in determining the magnitude of the negative pressure generated in each of the regions 701, 702, and 703. In this embodiment, in addition to the features of the first embodiment, the positions of the sixth through hole 141, the seventh through hole 142, and the eighth through hole 143 are changeable. This allows for adaptation to various shapes and molding conditions of the bubble 200. As a result, the versatility of the guide device 20 can be improved, reducing the need to prepare a dedicated guide plate each time to fit the shape of the bubble 200, which is determined depending on the type of resin used, molding conditions, etc.

[0054] That is, the positions of the sixth through hole 141, the seventh through hole 142, and the eighth through hole 143 shown in FIG. 4 are merely examples showing the positions of three through holes, among the many through holes provided in the fourth guide plate 14, that are opened according to the shape of the bubble 200 and molding conditions. The positions of the three through holes formed in the fourth guide plate 14 are merely examples, and through holes may be formed in other positions. Furthermore, although the fourth guide plate 14 has three through holes, the fourth guide plate 14 may have four or more through holes, or may have one or two through holes. Furthermore, the fourth guide plate 14 may not have any through holes.

[0055] 4 , the positional relationship between the first through hole 121 formed in the second guide plate 12, the second through hole 131 formed in the third guide plate 13, and the sixth through hole 141 formed in the fourth guide plate 14 is such that air from the outside is efficiently taken inward in the radial direction and easily merges with air 610 from the air outlet 21. Specifically, the sixth through hole 141 is positioned higher than the position of the second through hole 131 in the vertical direction, and the second through hole 131 is positioned higher than the position of the first through hole 121 in the vertical direction. This allows the flow of air 625 from the outside that hits the fourth guide plate 14 and moves downward in the vertical direction to pass through the sixth through hole 141, the second through hole 131, and the first through hole 121.

[0056] 4, the positional relationship between the third through hole 132 formed in the third guide plate 13 and the seventh through hole 142 formed in the fourth guide plate 14 is such that air from the outside is efficiently taken inward in the radial direction and easily merges with air 610 from the air outlet 21. Specifically, the seventh through hole 142 is disposed so as to be located higher than the position of the third through hole 132 in the vertical direction. This allows the flow of air 626 from the outside that hits the fourth guide plate 14 and moves downward in the vertical direction to pass through the seventh through hole 142 and the third through hole 132.

[0057] 4, the positional relationship between the fourth through hole 133 formed in the third guide plate 13 and the eighth through hole 143 formed in the fourth guide plate 14 is such that air from the outside is efficiently taken inward in the radial direction and easily merges with air 610 from the air outlet 21. Specifically, the eighth through hole 143 is disposed so as to be located closer to the top in the circumferential direction than the fourth through hole 133. This allows the flow of air 627 from the outside that hits the fourth guide plate 14 and moves downward in the circumferential direction to pass through the eighth through hole 143 and the fourth through hole 133.

[0058] In summary, the inflation molding apparatus 2 according to the second embodiment of the present invention only needs to have the following configuration, and can take on a variety of different embodiments. That is, in the inflation molding device 2, a first guide plate 11, a second guide plate 12, a third guide plate 13, and a fourth guide plate 14, which are cylindrical plates that guide a flow of air 610 passing through the outer surface side of the bubble 200, are arranged to form layers on the outer surface side of the bubble 200, formed by feeding air 600 into the inner surface side of the molten resin extruded in a cylindrical shape. Of the first guide plate 11, the second guide plate 12, the third guide plate 13, and the fourth guide plate 14 that form layers, the second guide plate 12 that forms the outer layer of the first guide plate 11 that forms the innermost layer has a first through hole 121 that penetrates the first guide plate 11 in the radial direction at a position on the upper side relative to a position in the vertical direction of a center 111 of the first guide plate 11. a third guide plate (13) that forms the outer layer of the second guide plate (12) is formed with a second through hole (131) and a third through hole (132) that radially penetrate through positions on the ground side and the top side of the center (123) of the second guide plate (12) in the vertical direction, and a fourth through hole (133) that radially penetrates through a position on the top side of the tip (120) of the second guide plate (12) in the vertical direction; and a fourth guide plate (14) that forms the outer layer of the third guide plate (13) is formed with a sixth through hole (141) and a seventh through hole (142) that radially penetrate through positions on the ground side and the top side of the center (134) of the third guide plate (13) in the vertical direction.

[0059] As a result, of the four guide plates that guide the flow of air 610 passing through the outer surface side of bubble 200, first through hole 121 formed in second guide plate 12, second through hole 131, third through hole 132, and fourth through hole 133 formed in third guide plate 13, and sixth through hole 141 and seventh through hole 142 formed in fourth guide plate 14 allow air 621 to 628 from the outside to pass radially inward from the outside and merge with air 610 from air outlet 21. Sufficient negative pressure is generated in the region where air 610 from air outlet 21 and air 621 to 628 from the outside merge, so that bubble 200 can be drawn toward the guide plates.

[0060] Here, the sixth through hole 141 may be characterized in that it is arranged on the upward side relative to the position of the second through hole 131 in the vertical direction. This makes it easier to send the air 621 from the outside that has passed through the sixth through-holes 141 toward the second through-holes 131.

[0061] The seventh through hole 142 may be characterized in that it is disposed on the upward side of the third through hole 132 in the vertical direction. This makes it easier to send the air 622 from the outside that has passed through the seventh through-hole 142 toward the third through-hole 132.

[0062] The fourth guide plate 14 may be characterized in that an eighth through hole 143 is further formed to penetrate the fourth guide plate 14 in the radial direction at a position on the upper side of the seventh through hole 142 in the vertical direction. As a result, the eighth through hole 143 allows some of the air from the outside that hits the radially outer surface of the fourth guide plate 14 to pass through, making it easier for negative pressure to occur in the area between the bubble 200 and the fourth guide plate 14.

[0063] The eighth through hole 143 may be characterized in that it is arranged on the upward side of the position of the fourth through hole 133 in the vertical direction. This makes it easier for the air 610 from the air outlet 21 to merge with the air from the outside that has passed through the eighth through-hole 143. As a result, negative pressure is more likely to be generated in the region between the bubble 200 and the fourth guide plate 14.

[0064] At least one of the sixth through hole 141, the seventh through hole 142, and the eighth through hole 143 may be characterized in that it opens and closes. This opens and closes at least one of the sixth through hole 141, the seventh through hole 142, and the eighth through hole 143, making it possible to control the negative pressure generated in the area where air from outside joins air 610 from the air outlet 21. As a result, the guide plate can be made more versatile than when a dedicated guide plate is prepared each time to fit each of the wide variety of bubble 200 shapes.

[0065] <Other> Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments. Furthermore, the effects of the present invention are not limited to those described in the above-described embodiments. For example, the configurations of the inflation molding apparatus 1 shown in FIGS. 1 and 2, the configuration of the inflation molding apparatus 2 shown in FIG. 4, and the configuration of the through-holes formed in the second guide plate 12 shown in FIG. 3 are merely examples for achieving the object of the present invention, and are not particularly limited.

[0066] Furthermore, for example, in the above-described embodiment, negative pressure is controlled by providing through holes at one or more locations on each of three or four layer guide plates, but negative pressure may also be controlled by providing through holes at one or more locations on each of one, two, or five or more layer guide plates. [Explanation of symbols]

[0067] 1, 2... inflation molding device, 10, 20... induction device, 11... first induction plate, 12... second induction plate, 13... third induction plate, 14... fourth induction plate, 21... air outlet, 31... die, 112... fifth through hole, 121... first through hole, 131... second through hole, 132... third through hole, 133... fourth through hole, 141... sixth through hole, 142... seventh through hole, 143... eighth through hole, 200... bubble, 600, 610, 621, 622, 623, 624, 625, 626, 627, 628... air

Claims

1. A plurality of guide plates, which are cylindrical plates that guide the flow of air passing through the outer surface of the bubbles formed by blowing air into the inner surface of the cylindrically extruded molten resin, are arranged on the outer surface of the bubbles to form layers, Among the guide plates forming the plurality of layers, a second guide plate forming an outer layer of a first guide plate forming an innermost layer has a first through-hole formed therein, the first through-hole penetrating radially through a position on the upper side of a center of the first guide plate in a vertical direction; a third guide plate forming an outer layer of the second guide plate has a second through hole and a third through hole formed therein, the second through hole penetrating radially through positions on the ground side and the top side of the center of the second guide plate in the top-bottom direction, respectively; An inflation molding apparatus characterized by:

2. A fourth through hole is further formed to penetrate the second guide plate in the radial direction at a position on the upper side than the position in the vertical direction of the tip end of the second guide plate. The inflation molding apparatus according to claim 1 .

3. The second through hole is disposed on the upper side of the first through hole in the vertical direction. The inflation molding apparatus according to claim 1 .

4. At least one of the first to fourth through holes is opened and closed. The inflation molding apparatus according to claim 2.

5. a fourth guide plate forming an outer layer of the third guide plate, a sixth through hole and a seventh through hole are formed radially penetrating positions on the bottom side and the top side of the center of the third guide plate in the vertical direction, The inflation molding apparatus according to claim 2.

6. The sixth through hole is disposed on the upper side of the second through hole in the vertical direction. The inflation molding apparatus according to claim 5.

7. The seventh through hole is disposed on the upper side of the third through hole in the vertical direction. The inflation molding apparatus according to claim 5.

8. The fourth guide plate is further formed with an eighth through hole that penetrates in a radial direction at a position on the top side of the seventh through hole in the top-bottom direction. The inflation molding apparatus according to claim 5.

9. The eighth through hole is disposed on the upper side of the fourth through hole in the vertical direction. The inflation molding apparatus according to claim 8.

10. At least one of the sixth to eighth through holes is opened and closed. The inflation molding apparatus according to claim 8.

11. A plurality of layers of guide plates, which are cylindrical plates that guide the flow of air passing through the outer surface of the bubbles formed by blowing air into the inner surface of the cylindrically extruded molten resin, are arranged on the outer surface of the bubbles, Among the guide plates forming the plurality of layers, a second guide plate forming an outer layer of a first guide plate forming an innermost layer has a first through hole formed therein, the first through hole passing through the first guide plate in a radial direction at a position on the upper side of a center of the first guide plate in a vertical direction, a third guide plate forming an outer layer of the second guide plate has a second through hole and a third through hole formed therein, the second through hole penetrating radially through positions on the ground side and the top side of the center of the second guide plate in the top-bottom direction, respectively; A guidance device characterized by:

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