JP2013099883A - Method of molding foam molded article and the foam molded article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a foam molded article capable of preventing gas blown into a foamed molten resin from flowing out to the outside.SOLUTION: A foam molded article (100) includes a fitting part (104) for fitting another member (not shown). The fitting part (104) includes a first tubular part (104a) comprising a foamed resin having a foaming ratio lower than that of a body part (102) of the foam molded article (100) and a second tubular part (104b) comprising a foamed resin having a foaming ratio lower than that of the first tubular part (104a) or an unfoamed resin.

Description

  The present invention relates to a method for molding a foam molded article and a foam molded article.

  A conventional method for forming a foamed molded article is to form a cylindrical foamed parison by extruding a foamed molten resin obtained by melting and kneading a base resin and a foaming agent from a die, and sandwiching the foamed parison with a split mold. Was blown by injecting a pressurized gas into the inside thereof to form a hollow foamed molded body (see, for example, Japanese Patent Laid-Open No. 63-309434).

  In addition, since the outer diameter of the foaming molded object shape | molded with the shaping | molding method mentioned above is controlled by the inner wall face (cavity surface) of a division mold, it can finish to a predetermined dimension. However, since the inner diameter of the foamed molded body is only restricted by the pressing force of the pressurized gas blown into the inside of the foam parison, it is difficult to finish to a predetermined dimension. For this reason, the foam molded body molded by the above-described molding method is likely to have a variation in thickness, which causes a problem when other members such as a register are fitted into the foam molded body.

  For example, when the inner diameter of the fitting portion into which the other member is fitted is larger than the outer diameter of the other member, a gap is generated between the fitting portion and the other member, and air leaks from the fitting portion, Other members may easily come off. Moreover, when the internal diameter of a fitting part becomes smaller than the outer diameter of another member, it will become difficult to fit another member to a fitting part. In particular, the parting line portion is prone to the occurrence of double-thickness, so that the resin swells on the inside of the foamed molded product, and the inner diameter of the fitting portion may not be a predetermined dimension.

  For this reason, it is necessary to regulate the inner diameter of the fitting portion into which the other member is fitted and finish it to a predetermined dimension with high accuracy.

  Patent Document 2 (Japanese Patent No. 4087209) discloses a method for regulating the inner diameter of a foamed molded product.

  In Patent Document 2, as shown in FIG. 9 (a), the foam parison 11 pushed out from the die 21 is disposed in the molds 22a and 22b, and the fitting portion forming gold is placed in the foam parison 11 from below. A mold 32 including a mold 31c and a mold 31d is inserted.

  Next, as shown in FIG. 9B, the foam parison 11 is sandwiched between the mold 22a and the mold 22b, and the molds 22a and 22b are closed while gas is blown into the foam parison 11. At this time, a portion sandwiched between the recesses 33a, 33b and the mold 31c is formed as a convex fitting portion, and a portion sandwiched between the straight portions 34a, 34b and the mold 31d is formed as a concave fitting portion. It is formed.

  Next, the molds 22a and 22b are opened, the foam molded body is taken out, unnecessary burrs are removed, and the convex fitting portion 4a and the concave fitting portion having a vertical cross section as shown in FIG. 4b is formed.

JP-A 63-309434 Japanese Patent No. 4087209

  In Patent Document 2, an inner diameter of the foam parison 11 is regulated by inserting a mold 32 including a mold 31c and a mold 31d for forming a fitting portion into the foam parison 11.

  However, in Patent Document 2, unless the foamed parison 11 sandwiched between the straight portions 34a and 34b and the mold 31d is sufficiently compressed to form the concave fitting portion 4b, the fitting portion 4b is formed around the fitting portion 4b. A gap is generated, and the gas blown into the foam parison 11 flows out of the foam parison 11 through the gap. As a result, the foam parison 11 cannot be sufficiently extended in the molds 22a and 22b by the pressure of the gas blown into the foam parison 11, and the foam parison 11 is brought into close contact with the cavity 24 of the molds 22a and 22b. It will cause a situation that cannot be done. In the above-mentioned patent document 2, since the combination molds 22a and 22b provided with the pressure reducing pipe 23 are used, the foam parison 11 can be formed in the cavity without increasing the pressure of the gas blown into the foam parison 11. Can be fully stretched within 24. However, when molding is performed only with the pressure of the gas blown into the inside of the foam parison 11 without using the decompression pipe 23, it is necessary to increase the pressure of the gas. It will be easy to flow out of the parison 11.

  For this reason, it is necessary to prevent the gas blown into the inside of the foamed molten resin that is the foam parison 11 from flowing out.

  The present invention has been made in view of the above circumstances, and provides a method for molding a foamed molded product and a foamed molded product capable of preventing the gas blown into the foamed molten resin from flowing out to the outside. With the goal.

  In order to achieve this object, the present invention has the following features.

<Method of forming foam molded article>
The molding method of the foamed molded product according to the present invention is:
A molding method for forming a hollow foamed molded article by sandwiching a foamed molten resin with a split mold,
A step of disposing an inner diameter regulating member for regulating an inner diameter of the foam molded body between the split molds;
Compressing the foamed molten resin disposed between the split mold and the inner diameter regulating member so that the split mold and the inner diameter regulating member have different thicknesses in at least two locations;
And a step of forming the foamed molded body by blowing a gas into the foamed molten resin sandwiched between the split molds.

<Foamed molded product>
The foamed molded product according to the present invention is
A foamed molded article having a fitting portion for fitting another member,
The fitting portion is
A first cylindrical portion made of a foamed resin having a foaming ratio lower than the foaming ratio of the main body part of the foamed molded article,
It has a 2nd cylindrical part which consists of a foamed resin lower than the expansion ratio of a said 1st cylindrical part, or an unfoamed resin, It is characterized by the above-mentioned.

  According to the present invention, it is possible to prevent the gas blown into the foamed molten resin from flowing out.

It is a perspective view which shows the duct 100 as a foaming molding of this embodiment, (a) is a front view of the duct 100, (b) is sectional drawing (fitting part) which follows the AA line of (a) (C) is a sectional view taken along line BB of (a) (cross section of the first cylindrical portion 104a constituting the fitting portion 104). (D) is a cross-sectional view (cross-sectional view of the duct body 102) taken along line CC of (a). 3 is a diagram showing an example of a method for forming a duct 100. FIG. The enlarged view of concave fitting formation part 34a, 34b and the metal mold | die 31d is shown, (a) shows the state before closing the divided metal molds 22a, 22b, (b) shows the divided metal molds 22a, 22b. The state after closing is shown. The example of a structure at the time of providing the compression part 44 in the concave fitting formation parts 34a and 34b is shown, (a) shows the state before closing the division molds 22a and 22b, (b) shows the division molds The state after closing 22a, 22b is shown. 5 is a diagram illustrating a configuration example of a fitting unit 104. FIG. The example of a structure at the time of providing the cut-off part 43 and the compression part 45 in the concave fitting formation part 34a, 34b is shown, (a) shows the state before closing the division molds 22a, 22b, (b ) Shows a state after the split molds 22a and 22b are closed. It is a figure which shows the example of a shaping | molding method of the duct 100 of 2nd Embodiment. 5 is a diagram illustrating an example of a method for arranging an inner diameter regulating member 32. FIG. It is a figure which shows the example of a shaping | molding method of the conventional foaming molding.

<Outline of Foam Molded Body 100 of the Present Embodiment>
First, an outline of the foamed molded product 100 of the present embodiment will be described with reference to FIGS. 1 and 2.

  As shown in FIG. 1, the foam molded body 100 of the present embodiment is a foam molded body 100 having a fitting portion 104 for fitting another member (not shown). The fitting portion 104 is foam molded. The first cylindrical portion 104a made of a foamed resin having a lower expansion ratio than the expansion ratio of the main body portion 102 of the body 100, and a foamed resin lower than the expansion ratio of the first cylindrical portion 104a, or an unfoamed resin And a second cylindrical portion 104b.

  In the foam molded body 100 of the present embodiment, for example, as shown in FIG. 2A, an inner diameter regulating member 32 that regulates the inner diameter of the foam molded body 100 is disposed between the divided molds 22a and 22b. Then, as shown in FIG. 2B, the foamed molten resin 11 disposed between the split molds 22a and 22b and the inner diameter regulating member 32 is replaced with the divided molds 22a and 22b and the inner diameter regulating member 32. It compresses so that it may become different thickness in at least 2 places (for example, two places of the fitting formation parts 34a and 34b shown in FIG.2 (b), and the cut-off part 43). Then, a foamed molded body 100 is molded by blowing a gas into the foamed molten resin 11 sandwiched between the divided molds 22a and 22b. Thereby, as shown in FIG. 2 (c), the first cylindrical portion 104a made of the foamed resin having a lower expansion ratio than the expansion ratio of the main body portion 102 of the foam molded body 100, and the first cylindrical portion 104a. Thus, a foamed molded product 100 having a fitting portion 104 composed of a foamed resin lower than the foaming ratio or a second cylindrical portion 104b made of an unfoamed resin is obtained.

  In the foam molded body 100 of the present embodiment, the foamed molten resin 11 disposed between the divided molds 22a and 22b and the inner diameter regulating member 32 is replaced with at least 2 by the divided molds 22a and 22b and the inner diameter regulating member 32. It compresses so that it may become different thickness in two places (for example, two places of fitting formation parts 34a and 34b shown in Drawing 2 (b), and cut-off part 43). For this reason, the fitting portion 104 has a first cylindrical portion 104a made of a foamed resin having a lower expansion ratio than the expansion ratio of the main body portion 102 of the foam molded body 100, and the expansion ratio of the first cylindrical portion 104a. The second cylindrical portion 104b made of a low foamed resin or a non-foamed resin can be configured. In addition, the foamed molten resin 11 disposed between the split molds 22a and 22b and the inner diameter regulating member 32 is placed between at least two locations (for example, FIG. 2 (b) between the split molds 22a and 22b and the inner diameter regulating member 32. ) Between the split molds 22a and 22b and the inner diameter regulating member 32, since the compression is made to have different thicknesses at the two fitting formation portions 34a and 34b and the cut-off portion 43) shown in FIG. It is possible to prevent a gap from being generated. As a result, it is possible to prevent the gas blown into the foamed molten resin 11 from flowing out. Hereinafter, with reference to the attached drawings, the foamed molded product and the molding method of the present embodiment will be described in detail. In the following embodiments, a duct that is an example of a foam molded body will be described in detail. The present invention is not limited to ducts, and can be applied to other foamed molded articles such as other automobile parts and containers.

(First embodiment)
<Configuration example of duct 100>
First, the duct 100 of this embodiment will be described with reference to FIG. 1A is a front view of the duct 100, and FIG. 1B is a cross-sectional view taken along the line AA of FIG. 1A (the second cylindrical portion 104b constituting the fitting portion 104). 1C is a cross-sectional view taken along line BB in FIG. 1A (a cross-sectional view of the first cylindrical portion 104a constituting the fitting portion 104), and FIG. d) is a cross-sectional view (cross-sectional view of the duct body 102) taken along the line CC of FIG.

  The duct 100 of this embodiment includes a duct body 102 and a concave fitting portion 104. The fitting portion 104 of the present embodiment includes a first tubular portion 104a made of a foamed resin having a foaming ratio lower than that of the duct body 102, and a foamed resin having a foaming ratio lower than that of the first tubular portion 104a. Or a second cylindrical portion 104b made of unfoamed resin. The inside of the duct 100 of the present embodiment has a hollow space (hollow part) 103. Further, parting lines L1, L2 are formed on the wall surface of the duct 100. Note that the configuration of the duct 100 illustrated in FIG. 1 is an example, and is not limited to the configuration illustrated in FIG. 1.

  The cross section shown in FIGS. 1B to 1D is a cross section perpendicular to the hollow extending direction of the duct 100 (the direction indicated by the arrow Z in FIG. 1), and FIG. FIG. 1C shows a cross section of a portion of the first cylindrical portion 104a constituting the fitting portion 104, and FIG. 1D shows a cross section of the portion of the second cylindrical portion 104b constituting the fitting portion 104. Fig. 5 shows a cross section of a portion of the duct body 102. In the duct 100 of the present embodiment, the foaming ratio of the first cylindrical portion 104a shown in FIG. 1 (c) is lower than that of the duct main body 102 shown in FIG. 1 (d). Further, the foaming ratio of the second cylindrical portion 104b shown in FIG. 1 (b) is lower than that of the first cylindrical portion 104a shown in FIG. 1 (c). The hollow extending direction is a direction in which the hollow portion 103 extends in the duct 100. When both ends are open like the duct 100 of the present embodiment, this hollow extending direction means a direction parallel to the ventilation path in the duct 100.

  The duct 100 of the present embodiment is made of a foamed molten resin obtained by melting and kneading a base resin mainly composed of a polyolefin resin and a foaming agent.

  As the polyolefin-based resin, high-density polyethylene resin, low-density polyethylene resin, polyethylene-based resin such as linear low-density polyethylene resin, polypropylene-based resin, and the like are applicable. In addition, polyolefin resin shall contain what copolymerized the olefin component and other components, such as styrene. As the polyolefin resin, it is particularly preferable to use a polypropylene resin excellent in mechanical properties such as heat resistance and rigidity.

  Examples of the foaming agent include inorganic physical foaming agents such as air, carbon dioxide, nitrogen gas and water, and organic physical foaming agents such as butane, pentane, hexane, dichloromethane and dichloroethane, or sodium bicarbonate, citric acid, citric acid. Chemical foaming agents such as sodium acid and azodicarbonamide are applicable. Furthermore, these physical foaming agents and chemical foaming agents can be used in combination.

  The duct 100 of the present embodiment can be formed in a range where the expansion ratio of the duct body 102 is 1.5 to 6.0 times, for example. The first cylindrical portion 104a constituting the fitting portion 104 of the duct 100 of the present embodiment has a lower expansion ratio than the portion of the duct main body 102 and is in the range of 1.2 to 3.0 times. The second cylindrical portion 104b is lower than the expansion ratio of the first cylindrical portion 104a and is in the range of 1.0 to 1.5 times (however, when the expansion ratio is 1.0 times, it is in an unfoamed state).

The expansion ratio was calculated as follows.
Test pieces were cut at 2 cm square from a total of three locations in the center of the duct body 102 and near both ends (excluding the fitting portion 104a). The specific gravity of the three test pieces was measured with an electronic specific gravity meter EW-200SG manufactured by Alpha Mirage Co., Ltd. according to JIS K-7112. The average specific gravity of the duct body 102 was calculated by arithmetically averaging the three specific gravity values. Then, the expansion ratio was calculated by dividing the specific gravity of the polyolefin resin before foaming by the average specific gravity.
The expansion ratio of the first cylindrical portion 104a and the second cylindrical portion 104b constituting the fitting portion 104 was also calculated in the same manner as described above.

  If the expansion ratio of the duct main body 102 is less than 1.5 times, there is a disadvantage that sufficient weight reduction cannot be achieved and condensation is likely to occur on the surface. In particular, the duct 100 for a vehicle has a drawback that the heat loss performance is poor when the expansion ratio of the duct body 102 is less than 1.5 times. On the other hand, when the expansion ratio of the duct body 102 exceeds 6.0 times, it is easily deformed by an external force.

The average thickness of the duct body 102 of the present embodiment is preferably 0.7 to 4.0 mm. The average thickness of the first tubular portion 104a constituting the fitting portion 104 is thinner than that of the duct body 102, and is preferably 0.6 to 3.0 mm. Furthermore, the average thickness of the second cylindrical portion 104b is thinner than that of the first cylindrical portion 104a, and is preferably 0.5 to 1.0 mm.
The average wall thickness was calculated as follows.
In the cross section of the three places in the center of the duct body 102 and in the vicinity of both ends (excluding the fitting portion 104a), the portions that intersect with the perpendicular bisector of the straight line connecting the two mold dividing points (total 6 The wall thickness was measured with calipers. And the average value of six measured values was computed as average thickness.
The average thickness of the first cylindrical portion 104a and the second cylindrical portion 104b constituting the fitting portion 104 was also calculated in the same manner as described above.
When the average thickness of the duct body 102 is less than 0.7 mm, the strength is weak and the duct body 102 is easily deformed by an external force. On the other hand, if the average thickness of the duct body 102 exceeds 4.0 mm, the thickness of the duct body with a high expansion ratio of 2.5 times or more is likely to vary, and the pressure loss when the wind flows is increased. .

<Example of molding method of duct 100>
Next, an example of a method for forming the duct 100 of the present embodiment will be described with reference to FIG. FIG. 2 is a view showing a configuration example around the split molds 22a and 22b of the molding apparatus for molding the duct 100 of the present embodiment.

  First, a base resin for forming the duct 100 is melt-kneaded in an extruder (not shown), a foaming agent is injected, and then extruded from the die 21 as shown in FIG. A foamed cylindrical foam parison 11 is formed, and the foam parison 11 is placed in the divided molds 22a and 22b. Further, from the lower side of the foam parison 11, an inner diameter regulating member 32 having a fitting portion forming die 31d is inserted into the foam parison 11.

  The molding apparatus according to the present embodiment includes a concave fitting formation portion 34a provided at a lower portion in the molding space of the split mold 22a and a concave fitting formation portion 34b provided at a lower portion in the molding space of the split mold 22b. Then, the concave fitting portion 104 is formed using the mold 31d.

  For this reason, the inner diameter regulating member 32 is inserted so that the mold 31d inserted into the foamed parison 11 is positioned between the concave fitting formation portions 34a and 34b.

  Next, as shown in FIG. 2 (b), the divided molds 22a and 22b are closed, and the foam parison 11 disposed between the divided molds 22a and 22b and the inner diameter regulating member 32 is replaced with the divided mold 22a. , 22b and the inner diameter regulating member 32 are compressed so as to have different thicknesses in at least two places (fitting formation portions 34a, 34b and cutout portion 43). Next, a gas is blown into the inside of the foam parison 11, and the duct 100 having the hollow portion 103 is formed.

  The molding apparatus of the present embodiment has a concave fitting provided in the split molds 22a and 22b when the split molds 22a and 22b are closed from the state shown in FIG. 3A to the state shown in FIG. The foamed parison 11 sandwiched between the forming portions 34a and 34b and the mold 31d constituting the inner diameter regulating member 32 is provided in the concave fitting forming portions 34a and 34b and the concave fitting forming portions 34a and 34b. It is compressed so as to have different thicknesses at the two cut-off portions 43. As a result, at the portion of the foam parison 11 sandwiched between the concave fitting formation portions 34a, 34b and the mold 31d, the portion 104a having a lower foaming ratio than the foam parison 11 extruded from the die 21 and subjected to primary foaming, A portion 104b that is lower than the portion 104a having a low expansion ratio can be formed. In the molding apparatus of the present embodiment, the first cylindrical portion 104a of the fitting portion 104 is formed at a portion 104a having a lower expansion ratio than the foamed parison 11 extruded from the die 21 and subjected to primary foaming. The second cylindrical portion 104b of the fitting portion 104 is formed at a portion 104b that is lower than the lower portion 104a. FIG. 3 shows an enlarged view of the concave fitting formation portions 34a and 34b forming the fitting portion 104 and the mold 31d, and FIG. 3A shows a state before the divided molds 22a and 22b are closed. FIG. 3 (b) shows a state after the divided molds 22a and 22b are closed. As shown in FIG. 3A, the cutout portion 43 has a compression width α at the tip of the cutout portion 43 that is narrower than the thickness β of the foam parison 11, and the thickness γ of the cutout portion 43 is 1.0. Consists of mm or less. As a result, the second cylindrical portion 104b having a lower expansion ratio than the first cylindrical portion 104a can be formed, and the portion of the second cylindrical portion 104b can be cut by the cutout portion 43. it can.

  As shown in FIG. 3 (b), the molding apparatus of the present embodiment is foamed in a compressed state so as to have different thicknesses at the two portions of the concave fitting formation portions 34a and 34b and the cut-off portion 43. The duct 100 having the hollow portion 103 is formed by blowing gas into the parison 11.

  In the molding apparatus of the present embodiment, a blowing part 41 for blowing gas into the inside of the foam parison 11 is provided in the mold 31d of the inner diameter regulating member 32, and gas (air) is introduced into the inside of the foam parison 11 via the blowing part 41. ).

  Since the molding apparatus of this embodiment is compressed so as to have different thicknesses at the concave fitting forming portions 34a and 34b and the cutout portion 43, the inside of the foam parison 11 is blown from the blowing portion 41. The gas blown into is difficult to flow out of the foamed parison 11 from between the concave fitting formation portions 34a and 34b provided in the divided molds 22a and 22b and the mold 31d constituting the inner diameter regulating member 32. It has become. In particular, the portion 104b compressed by the cut-off portion 43 formed on the entire circumference of the concave fitting formation portions 34a and 34b has a low expansion ratio and is in contact with the mold 31d. The gas blown into the inside does not leak to the outside of the foam parison 11. As a result, the foam parison 11 is stretched and deformed in the split molds 22a and 22b by the gas blown into the foam parison 11, and is in close contact with the cavity 24 of the split molds 22a and 22b. A duct 100 having a hollow portion 103 can be formed.

  Next, the split molds 22a and 22b are opened, and the duct 100 shown in FIG. In the molding apparatus of the present embodiment, the cutout portion 43 is formed on the entire circumference of the concave fitting formation portions 34a and 34b. Therefore, the fitting portion 104 is cut by the cutout portion 43, and FIG. The duct 100 having the fitting portion 104 shown in FIG. Next, unnecessary burrs are removed from the duct 100 shown in FIG. 2C taken out from the divided molds 22a and 22b, and the upper end of the duct 100 is cut with a cutter or the like. Thereby, the duct 100 having the concave fitting part 104 as shown in FIG. 1 can be formed.

  In the above embodiment, the inner diameter regulating member 32 is inserted into the foamed parison 11 after the foamed parison 11 is disposed in the divided molds 22a and 22b. However, after the inner diameter regulating member 32 is arranged in advance in the divided molds 22a and 22b, the foam parison 11 is arranged in the divided molds 22a and 22b so that the inner diameter regulating member 32 is positioned in the foamed parison 11. It is also possible to do. That is, as long as the inner diameter regulating member 32 can be disposed in the foam parison 11, the order of the steps is not particularly limited, and can be performed in any order.

  Moreover, in the said embodiment, it decided to shape | mold the duct 100 using blow molding and vacuum forming together. However, it is also possible to form the duct 100 using only blow molding. In the above embodiment, the blowing portion 41 is provided in the mold 31d of the inner diameter regulating member 32, and the gas is blown into the foam parison 11. However, the blow part 41 may not be provided in the mold 31d, and a blow pin may be inserted into the foam parison 11 and gas may be blown into the foam parison 11.

  Moreover, in the said embodiment, it comprised so that the outflow of gas might be prevented with the cut-off part 43 formed in the perimeter of the concave fitting formation parts 34a and 34b. However, if it is possible to prevent the outflow of gas, instead of the cutout portion 43, as shown in FIG. 4, a compression portion 44 is formed on the entire circumference of the concave fitting formation portions 34a and 34b, and the compression portion It is also possible to compress the foam parison 11 at 44 to prevent gas outflow. In this case, the second cylindrical part 104b is formed by the compression part 44. The compression part 44 compresses stronger than the concave fitting formation parts 34a and 34b forming the first cylindrical part 104a, and has a second cylindrical shape lower than the expansion ratio of the first cylindrical part 104a. This is a part forming the part 104b. As shown in FIG. 4, by providing the concave fitting formation portions 34a, 34b with a compression portion 44 that performs stronger compression than the concave fitting formation portions 34a, 34b forming the first cylindrical portion 104a, Similar to the cutout portion 43 shown in FIG. 3, the second tubular portion 104b having a lower expansion ratio than the first tubular portion 104a can be formed. However, the compression ratio of the second cylindrical portion 104b can be reduced by compressing the foam parison 11 with the cut-off portion 43 rather than compressing the foam parison 11 with the compression portion 44, and the cut-off portion 43 Thus, the second cylindrical portion 104b can be cut. As shown in FIG. 4, when the foamed parison 11 is compressed by the compression portion 44 to form the second tubular portion 104b, the second tubular portion 104b needs to be cut after the duct 100 is formed. is there.

  As shown in FIG. 3, when the cutout portion 43 is formed on the entire circumference of the concave fitting formation portions 34a and 34b, the second cylindrical portion 104b is cut at the cutout portion 43. As shown in FIG. 5, the end 104c of the second cylindrical portion 104b can be a free cut surface such as a curved shape instead of a linear shape. As a result, at least a part of the cut surface (end portion) 104c of the second cylindrical portion 104b can be formed to be recessed toward the duct body 102 side. FIG. 5 is a diagram illustrating a configuration example of the fitting unit 104. The second cylindrical portion 104b formed by the cutout portion 43 is hard because the expansion ratio is low, but at least a part of the cut surface 104c of the second cylindrical portion 104b is recessed toward the duct body 102 side. Due to the shape, the end 104c of the second cylindrical portion 104b is easily deformed. As a result, other members can be easily fitted into the fitting portion 104. For this reason, when the second cylindrical portion 104b is formed by the cutout portion 43, the second cylindrical portion 104b is cut by the cutout portion 43, so that the cut surface of the second cylindrical portion 104b is used. Instead of a linear shape, it can be a curved shape. As a result, it is possible to form the fitting portion 104 having the second cylindrical portion 104b into which other members can be easily fitted.

  In the above-described embodiment, the concave fitting formation portions 34a and 34b are configured in a shape corresponding to the outer shape of the mold 31d, and the concave fitting formation portions 34a and 34b in a state where the divided molds 22a and 22b are closed. The inner peripheral shape of 34b and the outer peripheral shape of the mold 31d are made the same shape, and the cut-off portion 43 or the compression portion 44 is provided to the concave fitting formation portions 34a, 34b, and the concave fitting formation portion The foam parison 11 sandwiched between 34a, 34b and the mold 31d is formed by the concave fitting formation portions 34a, 34b and the cut-off portion 43 or the compression portion 44 provided in the concave fitting formation portions 34a, 34b. It compressed so that it might become different thickness in two places. However, if the foamed parison 11 sandwiched between the concave fitting formation portions 34a and 34b and the mold 31d can be compressed so as to have different thicknesses, the concave fitting formation portions 34a, The shape of 34b is not particularly limited, and the concave fitting formation portions 34a and 34b are configured by flat surfaces, and the cut-off portion 43 or the compression portion 44 may be provided in a part of the concave fitting formation portions 34a and 34b. Is possible.

  Further, as shown in FIG. 6, the molding apparatus of the present embodiment can be provided with a cut-off portion 43 and a compression portion 45 in the concave fitting formation portions 34a and 34b. In FIG. 6, a compression fitting 45 for forming a third cylindrical portion 104d having a lower expansion ratio than the first cylindrical portion 104a is formed in a part of the first cylindrical portion 104a as a concave fitting formation portion. The example of a structure provided in 34a, 34b is shown. As shown in FIG. 6A, this type of compression unit 45 has a compression width α1 at the tip of the compression unit 45 wider than the compression width α at the tip of the cutout portion 43, and the thickness of the compression unit 45. γ1 is configured to be less than the thickness γ of the cut portion 43. Accordingly, it is possible to form the third cylindrical portion 104d having a lower expansion ratio than that of the first cylindrical portion 104a and a higher expansion ratio than that of the second cylindrical portion 104b. In addition, as shown in FIG. 6, with respect to the concave fitting formation parts 34a and 34b which form the 1st cylindrical part 104a, the cutting part 43 which comprises the 2nd cylindrical part 104b, and 3rd By providing the compression portion 45 that constitutes the cylindrical portion 104d, it is possible to prevent the gas from flowing out in stages at the compression portion 45 and the cut-off portion 43. Can be further prevented. It is also possible to provide the cutout portion 43 at a location where the compression portion 45 shown in FIG. 6 is provided.

<Operation / Effect of Duct 100 of this Embodiment>
Thus, in the present embodiment, the inner diameter regulating member 32 that regulates the inner diameter of the duct 100 is disposed between the divided molds 22a and 22b, and the fitting forming portions 34a and 34b provided in the divided molds 22a and 22b. The foam parison 11 disposed between the inner diameter regulating member 32 and the fitting forming portions 34a, 34b and at least the cut-off portion 43 or the compression portion 44 provided in the fitting forming portions 34a, 34b. Compress to different thicknesses at two locations. Then, a gas 100 is blown into the inside of the foam parison 11 to form the duct 100 having the hollow portion 103. Thereby, the fitting part 104 comprised by the 1st cylindrical part 104a lower than the expansion ratio of the duct main body 102, and the 2nd cylindrical part 104b lower than the expansion ratio of the 1st cylindrical part 104a. A duct 100 having the following can be formed. The second cylindrical portion 104b is formed by being compressed by the cut-off portion 43 or the compression portion 44 provided in the fitting formation portions 34a and 34b, and has a low foaming ratio. It is possible to prevent a gap from being generated between the portions 34a and 34b. As a result, the outflow of the gas blown into the inside of the foam parison 11 can be prevented.

(Second Embodiment)
Next, a second embodiment will be described.

  In the first embodiment, as shown in FIG. 2, the duct 100 is formed using a cylindrical foamed parison 11 formed by extruding a foamed molten resin into a cylindrical shape. In the second embodiment, as shown in FIG. 7, the duct 100 is formed using a sheet-shaped foamed parison P formed by extruding a foamed molten resin into a sheet. Also in this case, by using the inner diameter regulating member 32 similar to that in the first embodiment, the fitting portion 104 similar to that in the first embodiment can be formed. However, in this embodiment, since the sheet-like foam parison P is used, the inner diameter regulating member 32 can be easily placed in the foam parison P as compared with the case where the cylindrical foam parison 11 is used as in the first embodiment. The fitting portion 104 can be formed in addition to the end portion of the duct 100.

  In the first embodiment, since the cylindrical foam parison 11 is used, it is necessary to insert the inner diameter regulating member 32 into the foam parison 11 from below the foam parison 11 as shown in FIG. Further, the fitting portion 104 can be formed only at the end portion of the duct 100.

  On the other hand, in this embodiment, since the sheet-like foam parison P is used, as shown in FIG. 7, the inner diameter regulating member 32 is not only below the foam parison P but also as shown in FIG. Moreover, it can be inserted into the foam parison P even from the side of the foam parison P. As a result, as shown in FIG. 8B, the fitting portion 104 can be formed on the side other than the end portion of the duct 100. Even when the fitting portion 104 is formed on the side other than the end portion of the duct 100, the first cylindrical portion 104a lower than the expansion ratio of the duct main body 102 and the expansion ratio of the first cylindrical portion 104a. The fitting part 104 comprised by the low 2nd cylindrical part 104b can be formed.

<Operation / Effect of Duct 100 of this Embodiment>
In this manner, by forming the duct 100 using the sheet-like foam parison P, the inner diameter regulating member 32 can be easily inserted into the foam parison P, and the fitting portion 104 is formed at an arbitrary location. can do.

  The above-described embodiment is a preferred embodiment of the present invention, and the scope of the present invention is not limited to the above-described embodiment alone, and various modifications are made without departing from the gist of the present invention. Implementation is possible.

  For example, in the above-described embodiment, since the curved duct 100 is formed, the fitting portion 104 is formed using the inner diameter regulating member 32 only on the lower end side of the duct 100. However, in the case of a straight duct 1 like the duct 1 shown in FIG. 9, the fitting portion 104 of the present embodiment described above can be formed also on the upper end side of the duct 1 using the inner diameter regulating member 32. .

  In the above-described embodiment, the duct 100 having the fitting portion 104 is formed using the inner diameter regulating member 32. However, the fitting portion 104 is not fitted into another member, and can also be used as an opening for allowing gas to flow into the duct 100 or gas to flow out of the duct 100.

DESCRIPTION OF SYMBOLS 100 Duct 102 Duct main body 103 Hollow part 104 Fitting part 104a 1st cylindrical part 104b 2nd cylindrical part 104c End part L1, L2 Parting line 21 Die 11 Foam parison (cylindrical shape)
22a, 22b Split mold 23 Pressure reducing pipe 24 Cavity 31d Mold 32 Inner diameter regulating member 34a, 34b Recessed fitting forming part 41 Blowing part 43 Cutout part (compression part)
44, 45 Compression part P Parison (sheet)
51 T die

Claims (6)

A molding method for forming a hollow foamed molded article by sandwiching a foamed molten resin with a split mold,
A step of disposing an inner diameter regulating member for regulating an inner diameter of the foam molded body between the split molds;
Compressing the foamed molten resin disposed between the split mold and the inner diameter regulating member so that the split mold and the inner diameter regulating member have different thicknesses in at least two locations;
Forming the foamed molded body by blowing a gas into the foamed molten resin sandwiched between the split molds.   2. The fitting portion for fitting another member into the foamed molded body is formed by the foamed molten resin disposed between the split mold and the inner diameter regulating member. Molding method.   The molding method according to claim 1 or 2, wherein the foamed molded article is molded using the foamed molten resin extruded into a sheet shape. A foamed molded article having a fitting portion for fitting another member,
The fitting portion is
A first cylindrical portion made of a foamed resin having a foaming ratio lower than the foaming ratio of the main body part of the foamed molded article,
A foamed molded article having a foamed resin lower than a foaming ratio of the first tubular part or a second tubular part made of an unfoamed resin.   The foamed molded article according to claim 4, wherein the second cylindrical portion constitutes an end portion on a side into which the other member is fitted.   6. The foam molded article according to claim 5, wherein at least a part of the cut surface of the end portion is recessed toward the main body portion side of the foam molded article.

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