JP6969530B2 - Hollow member molding method - Google Patents

Description

The present invention relates to a molding method for molding a hollow member having a hollow space.

Conventionally, a method of forming a hollow member such as an air conditioning duct is known (for example, Patent Document 1). The method described in Patent Document 1 can cope with a complicated shape of a hollow member. The hollow member as a finished product has, for example, a main body portion having a hollow space, an opening opening in a part of the main body portion, and a flange portion formed on the peripheral edge of the opening portion. In this method of forming a hollow member, first, an intermediate is formed by applying a predetermined pressure to the hollow space of the closing member and pressing the outer surface of the closing member against the mold. Then, the waste bag portion, which is a part of the intermediate, is cut and removed in order to form the opening portion and the flange portion. This waste bag portion is a bag-shaped portion having a bottom wall portion. When the waste bag portion of the intermediate is removed, a hollow member in which a part of the main body portion is opened is formed.

Japanese Unexamined Patent Publication No. 2002-243252

By the way, the hollow member as a finished product includes a flange portion extending inward from the opening end of the side wall of the main body portion to the inside of the hollow space, and a standing wall portion extending from the inner tip of the flange portion to the bottom of the discard bag portion. Have. That is, the hollow member has a step bending portion having a flange portion and a standing wall portion on the peripheral edge of the opening. The waste bag portion of the intermediate is continuously formed at the bottom of the vertical wall portion of the hollow member, and has a bottom wall portion that closes the hollow space. When such an intermediate is formed by applying pressure to the hollow space, the pressure remaining in the hollow space then acts on the bottom wall portion of the waste bag portion as a force for pressing the waste bag portion to the outside of the bag. Then, the waste bag portion is stretched in a direction away from the remaining portion of the hollow member. Assuming that the starting point of such stretching is on the standing wall portion of the step bending portion connected to the waste bag portion in the intermediate, the stretching causes the thickness of the standing wall portion to be reduced, and thus the thinning is performed. As a result, the hollow member after molding is easily deformed, and the rigidity of the hollow member is reduced.

The present invention has been made in view of such a point, and provides a method for forming a hollow member capable of suppressing thinning in which the thickness of the vertical wall portion connected to the waste bag portion of the intermediate is reduced. The purpose is.

One aspect of the present invention is a first step of molding an intermediate having a closed hollow space while applying a predetermined pressure to the hollow space, and a part of the intermediate formed by the first step. The first step comprises a second step of forming a hollow member which is a remaining portion of the intermediate body by removing a bag-shaped waste bag portion having a bottom wall portion. The remaining portion includes a first flange portion extending inward from the opening side tip of the side wall of the remaining portion to the inside of the hollow space, and a first standing wall portion extending inward from the inner tip of the first flange portion to the bottom of the waste bag portion. The first step bending portion to have is formed, and the waste bag portion has a second standing wall portion and the second standing wall portion extending downward continuously to the bottom tip of the first standing wall portion of the first step bending portion. A second step bending portion having a second flange portion extending inward from the bottom tip of the standing wall portion to the inside of the hollow space and a third standing wall portion extending from the inner tip of the second flange portion to the bottom is formed. As described above, it is a molding method of a hollow member for molding the intermediate body.

According to this configuration, in the molding of the intermediate body, the first step bending portion is formed in the remaining portion of the hollow member and the second step bending portion is formed in the waste bag portion while applying a predetermined pressure to the hollow space. It is done like this. In the structure of this intermediate, when the waste bag portion is stretched in a direction away from the rest of the hollow member due to the pressure action of the hollow space, the base point of the stretch is mainly directly connected to the bottom wall portion. It becomes the third standing wall part of the bent part. Therefore, it is possible to suppress the thinning of the thickness of the first standing wall portion connected to the waste bag portion of the intermediate, which is the remaining portion of the hollow member.

It is a perspective view of the hollow member which concerns on embodiment. FIG. 2 is a sectional view taken along line II-II of the hollow member shown in FIG. FIG. 3 is a sectional view taken along line III-III of the hollow member shown in FIG. It is an IV arrow view of the hollow member shown in FIG. It is a flowchart showing the procedure of molding the hollow member which concerns on embodiment. It is a figure (the 1) which showed the method of molding the hollow member which concerns on embodiment with a molding apparatus. It is a figure (the 2) which showed the method of molding the hollow member which concerns on embodiment with a molding apparatus. It is a figure for demonstrating the effect in molding the hollow member which concerns on embodiment.

Hereinafter, a specific embodiment of the method for forming a hollow member according to the present invention will be described with reference to FIGS. 1 to 8.

First, the configuration of the hollow member 1 molded by the molding method of the present embodiment will be described.

The hollow member 1 is a member used for, for example, an air conditioning duct of a vehicle. The hollow member 1 is arranged on the back side of the instrument panel in the vehicle interior, for example, and guides the temperature-controlled air sent from the air conditioner unit to the air outlet formed in the instrument panel. As shown in FIG. 1, the hollow member 1 has a main body portion 2 and an opening portion 3. As shown in FIG. 2, the main body 2 has a hollow space 4 through which a fluid such as temperature-controlled air flows. The opening 3 is a portion connected to the hollow space 4 and opened to the outside provided in the terminal of the main body 2. The peripheral edge of the opening 3 of the hollow member 1 is attached to the peripheral edge of the outlet of the instrument panel or the like. The opening 3 communicates with the outlet of the instrument panel or the like.

The hollow member 1 also has a first step bent portion 5. The first step bent portion 5 is provided in a stepped or bent shape along the peripheral edge of the opening 3. The first step bent portion 5 is formed in a frame shape over the entire circumference of the peripheral edge of the opening 3. The first step bending portion 5 is a portion for attaching the hollow member 1 to the peripheral edge of the air outlet or the like.

The first step bent portion 5 has a first flange portion 6 and a first standing wall portion 7. The first flange portion 6 is formed from the tip of the side wall 8 of the main body 2 on the opening 3 side (that is, the tip of the waste bag portion described later on the bottom wall side) to the inside of the hollow space 4 (that is, the method of the side wall 8). (Linear direction) It is a part extending in X. The first flange portion 6 is a sticking allowance for attaching the hollow member 1 to the peripheral edge of the air outlet or the like. The first standing wall portion 7 is a portion extending from the inner tip of the first flange portion 6 to the bottom Y of the discard bag portion and projecting. The first standing wall portion 7 has a reinforcing portion 9 as shown in FIGS. 3 and 4. The reinforcing portion 9 is a rib or bead that enhances the rigidity of the first standing wall portion 7, and has a function of preventing deformation of the first standing wall portion 7 after molding of the hollow member 1. The reinforcing portion 9 may be provided on a part of the first standing wall portion 7 in the entire circumference of the peripheral edge of the opening 3. Further, the reinforcing portion 9 may have repeated irregularities due to the bead arrangement.

The hollow member 1 is formed of a thermoplastic resin such as polyethylene or polypropylene. The hollow member 1 is formed by twin composite molding. As shown in FIG. 2, the hollow member 1 removes a part of the intermediate body 13 from the intermediate body 13 to which the pair of U-shaped members 11 and 12 formed in a U-shaped cross section are joined by a cut line CL. It is molded by.

As shown in FIG. 6, the pair of U-shaped members 11 and 12 are composed of two thermoplastic resin sheets 11A and 12A. Each of the thermoplastic resin sheets 11A and 12A has a thickness of, for example, about 5 mm. In the pair of U-shaped members 11 and 12, two thermoplastic resin sheets 11A and 12A are arranged to face each other and are sandwiched between the molds 30 and 31 described later, and a predetermined pressure is applied between the sheets 11A and 12A. By following the shape of the cavities of the molds 30 and 31, each of them is formed into a U-shaped cross section (see FIG. 7). Further, the pair of U-shaped members 11 and 12 are joined to each other by heat-welding the sandwiching portions 11B and 12B of the sheets 11A and 12A sandwiched by the molds 30 and 31 to each other. The intermediate body 13 is formed in a state in which the hollow space 4 is surrounded and closed by the pair of U-shaped members 11 and 12.

The hollow member 1 is formed by cutting and removing a bag-shaped bottom portion, which is a part of the U-shaped member 12 of the pair of U-shaped members 11 and 12, from the molded intermediate body 13 with a cut line CL. Will be done. Hereinafter, the bottom portion to be cut and removed is referred to as a discard bag portion 20. The hollow member 1 is a remaining portion in which a part (specifically, the opening 3) of the intermediate 13 is opened by removing the waste bag portion 20 from the intermediate 13.

The intermediate body 13 is formed in a shape in which a waste bag portion 20 is added to the hollow member 1. The waste bag portion 20 is a bag-shaped portion continuous with the first standing wall portion 7 of the first step bending portion 5 of the remaining portion (that is, the hollow member 1) in the intermediate body 13. The discard bag portion 20 has a bottom wall portion 21 and a second step bent portion 22. The bottom wall portion 21 is a portion forming the bottom wall of the waste bag portion 20. The second step bending portion 22 is provided in a stepped or bent shape along the peripheral edge of the opening corresponding to the opening 3 of the hollow member 1. The second step bent portion 22 is formed in a frame shape over the entire circumference of the peripheral edge of the opening. The second step bent portion 22 is formed in the inner side of the intermediate body 13 than the first step bent portion 5, that is, in the inner X of the closed hollow space 4, and is a region one size smaller than the first step bent portion 5. It is formed inside.

The second step bending portion 22 has a second standing wall portion 23, a second flange portion 24, and a third standing wall portion 25. The second standing wall portion 23 is a portion that extends continuously to the first standing wall portion 7 of the first step bending portion 5 and extends to the bottom Y, which is the bottom wall portion 21 of the discard bag portion 20. The second flange portion 24 is a portion extending from the bottom tip of the second standing wall portion 23 to the inner X of the hollow space 4. The third vertical wall portion 25 is a portion extending from the inner tip of the second flange portion 24 to the bottom Y, which is the bottom wall portion 21 of the discard bag portion 20. As shown in FIG. 8, the waste bag portion 20 is formed so that the surface area of the portion of the second flange portion 24 facing the hollow space 4 is smaller than the surface area of the portion of the bottom wall portion 21 facing the hollow space 4. ..

Next, the molding method of the hollow member 1 will be described.

As shown in FIGS. 6 and 7, the hollow member 1 is formed by using two molds 30 and 31. The molds 30 and 31 have cavities 30A and 31A. The cavities 30A and 31A have a shape that matches the outer shape of the intermediate body 13. The molds 30 and 31 are arranged so as to face each other so that the cavities 30A and 31A communicate with each other. The molds 30 and 31 are movable in a direction in which they are separated from each other.

The cavity 30A of the mold 30 is formed in a shape in which the U-shaped member 11 which is the remainder of the hollow member 1 of the intermediate 13 is circumscribed. Specifically, the cavity 30A is formed in a shape that matches the U-shaped member 11 having a bottom wall portion and a side wall portion. The cavity 31A of the mold 31 is formed in a shape in which the U-shaped member 12 including the discard bag portion 20 of the intermediate 13 is circumscribed. Specifically, the cavity 31A is formed in a shape that matches the U-shaped member 12 having the bottom wall portion 21, the first step bending portion 5, and the second step bending portion 22.

At the time of molding the hollow member 1, first, as shown in FIG. 6, the thermoplastic resin sheets 11A and 12A are inserted between the molds 30 and 31 in a state where the molds 30 and 31 are separated from each other, and the cavities 30A and 31A are inserted. It is placed facing each other within. After that, the molds 30 and 31 approached each other to sandwich the thermoplastic resin sheets 11A and 12A, and both the sheets 11A and 12A were gripped by a clamp member (not shown) on the outside of the molds 30 and 31. In this state, a predetermined pressure is applied between both sheets 11A and 12A.

When the thermoplastic resin sheets 11A and 12A are sandwiched by the molds 30 and 31, the sandwiching portions 11B and 12B of the sheets 11A and 12A are joined by heat welding to each other. Further, when a predetermined pressure is applied between the thermoplastic resin sheets 11A and 12A, as shown in FIG. 7, the space between the sheets 11A and 12A expands to form a hollow space 4, and the sheets 11A and 12A are made of gold. By being pressed against the cavities 30A and 31A of the molds 30 and 31, a pair of U-shaped members 11 and 12 having a U-shaped cross section following the groove shape of the cavities 30A and 31A are formed. The application of the predetermined pressure is continued until the U-shaped members 11 and 12 are formed into a desired shape.

As a result, an intermediate 13 is formed in which a pair of U-shaped members 11 and 12 formed in a U-shaped cross section following the groove shape of the cavities 30A and 31A are joined by heat welding from the thermoplastic resin sheets 11A and 12A, respectively. (Step S100 shown in FIG. 5). In the molded intermediate 13, the hollow space 4 is surrounded and closed by a pair of U-shaped members 11 and 12.

After the intermediate body 13 is formed as described above, when the molds 30 and 31 are separated from each other and the intermediate body 13 is pulled out from the molds 30 and 31, the discard bag portion 20 is cut line CL from the intermediate body 13. It is cut and removed with. As a result, the hollow member 1 having the opening 3 opened is formed (step S110).

In this way, it is possible to form the intermediate body 13 including the waste bag portion 20 that closes the hollow space 4 to which the pair of U-shaped members 11 and 12 are joined by applying pressure between the thermoplastic resin sheets 11A and 12A. At the same time, by removing the waste bag portion 20 from the intermediate body 13 with the cut line CL, the hollow member 1 in which the opening 3 is opened and the hollow space 4 communicates with the outside through the opening 3 is formed. be able to.

As described above, the intermediate body 13 is formed so that the hollow space 4 is closed by the pair of U-shaped members 11 and 12. When the intermediate body 13 is formed by applying pressure to the hollow space 4, the pressure remaining in the hollow space 4 is subsequently applied to the bottom wall portion 21 of the waste bag portion 20 until the waste bag portion 20 is removed. By acting as a force for pressing the waste bag portion to the outside of the bag, the waste bag portion 20 is stretched and deformed in a direction away from the remaining portion of the hollow member 1.

The intermediate 13 has a first step bent portion 5 formed on the remaining side of the hollow member 1 and a second step bent portion 22 formed on the discard bag portion 20. The base point of the stretching in the intermediate 13 is mainly the third standing wall portion 25 directly connected to the bottom wall portion 21. When the waste bag portion 20 is stretched with the third standing wall portion 25 as a base point, the thickness of the third standing wall portion 25 is reduced, but the thickness of the third standing wall portion 25 is reduced, but the first standing wall portion 7 and the first step bending portion 5 are thinned. Thinning is unlikely to occur in the portion of the two-step bent portion 22 that is continuous with the second standing wall portion 23. The third standing wall portion 25 is a portion provided in the second step bending portion 22 formed in the waste bag portion 20.

For this reason, thinning in which the thickness is reduced occurs in the waste bag portion 20, but is unlikely to occur in the remaining portion of the hollow member 1. Therefore, according to the structure of the intermediate body 13 and the molding method of the hollow member 1, the thickness of the first standing wall portion 7 connected to the waste bag portion 20 of the intermediate body 13, which is the remaining portion of the hollow member 1, is reduced. Can be suppressed.

The waste bag portion 20 is provided and formed in the cavities 30A and 31A of the molds 30 and 31. In such a structure, as compared with the structure in which the waste bag portion 20 is provided in the mold split portion, the discard bag portion 20 is removed from the remaining portion of the hollow member 1 due to the pressure applied to the hollow space 4 after the intermediate 13 is formed. Deformation of the intermediate body 13 stretched in the direction of separation is likely to occur, but as described above, the presence of the second step bending portion 22 and thus the third standing wall portion 25 suppresses the thinning of the first standing wall portion 7. Therefore, even when the intermediate 13 is easily deformed by the pressure applied to the hollow space 4, it is possible to effectively suppress the thinning of the first standing wall portion 7.

Further, the second step bending portion 22 is formed inward of the hollow space 4 than the first step bending portion 5, and is formed in a region one size smaller than the first step bending portion 5. .. Therefore, the waste bag portion 20 in which the second step bent portion 22 is formed can be taken out from the mold 31 without forcibly removing it.

Further, in the waste bag portion 20, the surface area of the portion 24A facing the hollow space 4 in the second flange portion 24 is smaller than the surface area of the portion 21A facing the hollow space 4 in the bottom wall portion 21. In such a structure, the pressing force acting on the bottom wall portion 21 due to the applied pressure of the hollow space 4 can be made larger than the pressing force acting on the specific portion 24A of the second flange portion 24, so that the waste bag portion 20 can be used. The deformation of the third standing wall portion 25 can be promoted as compared with the deformation of the first standing wall portion 7. Therefore, the effect of suppressing the thinning of the first standing wall portion 7 can be enhanced.

Further, the hollow member 1 has a reinforcing portion 9 provided on the first standing wall portion 7. If the first standing wall portion 7 is provided with the reinforcing portion 9, the deformation of the first standing wall portion 7 is suppressed. In particular, even when the waste bag portion 20 is stretched from the remaining portion of the hollow member 1 due to the pressure in the hollow space 4 described above, the thinning of the first standing wall portion 7 is suppressed. Therefore, the effect of suppressing the thinning of the first standing wall portion 7 of the hollow member 1 can be further enhanced.

By the way, in the above embodiment, the hollow member 1 is formed by twin composite molding using two thermoplastic resin sheets 11A and 12A. However, the present invention is not limited to this. The hollow member 1 may be formed by blow molding or the like for forming a closed member having a closed hollow space.

Further, in the above embodiment, the surface area of the waste bag portion 20 facing the hollow space 4 in the second flange portion 24 is smaller than the surface area of the portion 21A facing the hollow space 4 in the bottom wall portion 21. It is supposed to be formed in. However, the present invention is not limited to this. The surface area of the portion 24A facing the hollow space 4 in the second flange portion 24 does not have to be smaller than the surface area of the portion 21A facing the hollow space 4 in the bottom wall portion 21.

Further, in the above embodiment, the waste bag portion 20 is provided and formed in the cavities 30A and 31A of the molds 30 and 31. However, the present invention is not limited to this. The discard bag portion 20 may be provided in the mold split portion to be formed.

The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

1: Hollow member 2: Main body 3: Opening 4: Hollow space 5: First step bending part, 6: First flange part, 7: First standing wall part, 8: Side wall, 9: Reinforcing part , 11, 12: U-shaped member, 11A, 12A: Thermoplastic resin sheet, 11B, 12B: Holding part, 13: Intermediate, 20: Waste bag part, 21: Bottom wall part, 22: Second step bending part, 23: Second standing wall part, 24: Second flange part, 25: Third standing wall part.

Claims (6)

The first step of molding an intermediate having a closed hollow space while applying a predetermined pressure to the hollow space,
By removing the bag-shaped waste bag portion having the bottom wall portion, which is a part of the intermediate formed by the first step, the hollow member which is the remaining portion of the intermediate having a part opened is removed. The second step of molding and
Equipped with
In the first step, the first flange portion extending inward of the hollow space from the opening-side tip of the side wall of the remaining portion and the inner tip of the first flange portion to the bottom of the waste bag portion. A first step bending portion having an extending first standing wall portion is formed, and the waste bag portion is continuously extended downward to the bottom tip of the first standing wall portion of the first step bending portion. A second having a second standing wall portion, a second flange portion extending inward from the bottom tip of the second standing wall portion to the inside of the hollow space, and a third standing wall portion extending downward from the inner tip of the second flange portion. A method for forming a hollow member, which forms the intermediate body so that a step bending portion is formed. In the intermediate, two thermoplastic resin sheets are arranged facing each other and a predetermined pressure is applied between the two thermoplastic resin sheets in a state of being sandwiched by a mold, and the two thermoplastic resin sheets are held. A pair of U-shaped members formed in a U-shaped cross section are joined to each other by heat-welding the sandwiching portions of the resin sheet to each other.
The hollow member according to claim 1, wherein the waste bag portion is a bottom portion of any one of the pair of U-shaped members of the intermediate formed by the first step. Molding method. The method for forming a hollow member according to claim 1 or 2, wherein the waste bag portion is provided in a cavity of a mold and is formed. The method for molding a hollow member according to any one of claims 1 to 3, wherein the second step bent portion is formed inside the hollow space from the first step bent portion. The surface area of the portion of the second step bent portion facing the hollow space in the second flange portion is smaller than the surface area of the portion of the bottom wall portion of the waste bag portion facing the hollow space, claims 1 to 4. The method for forming a hollow member according to any one of the above items. The method for forming a hollow member according to any one of claims 1 to 5, wherein the remaining portion is formed so that a reinforcing portion is provided on the first standing wall portion.

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