JPH11192655A - Hollow double-wall structure and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hollow double-wall structure and its manufacturing method, where deformation caused by shrinking by cooling after molding does not generate, even if a strength and a rigidity are improved by inserting a metallic bar-shaped reinforcing member. SOLUTION: A hollow double-wall structure is composed of a face wall 2, a back wall 3 facing the face wall with a gap therebetween, and a peripheral wall 4 for forming a hollow part 5 between the face wall 2 and the back wall 3. A bar-shaped reinforcing member 6 is arranged in the hollow 5. A part of the back wall 3 corresponding to an end of the bar-shaped reinforcing member 6 has a holding member 8 for holding the bar-shaped reinforcing material 6 in the hollow double-wall structure. The holding member 8 has a function to absorb deformation of the hollow double-wall structure with respect to the bar-shaped reinforcing member 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hollow double-walled structure obtained by blow molding a thermoplastic, and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, an inner wall formed in a hollow portion of a plastic hollow double-walled structure constituting an interior wall, a partition, a door of a building, a floor trunk lid or a rear parcel elf of an automobile or the like. A technique for improving strength and rigidity by inserting a flat and curved rod into a rib is described in Japanese Patent Application Laid-Open No. 9-155957.

[0003]

SUMMARY OF THE INVENTION The above-mentioned Japanese Patent Application Laid-Open No. 9-15 / 1997
The technology described in Japanese Patent No. 5957 was developed by the present applicant, but as a result of subsequent studies, it has been found that the following problems mainly exist in blow molding.

That is, in the technique described in Japanese Patent Application Laid-Open No. 9-155957, a rod-like body inserted into a blow-molded hollow double-walled structure is made of metal and shrinks with a resin generated during cooling. Since the difference is as large as 2% or more, for example, when a rod having a length of 800 mm is inserted into the hollow double-walled structure, a shrinkage difference of 16 mm or more occurs at both ends during cooling. The deformation or breakage of the wall structure.

In view of the above, an object of the present invention is to solve the above-mentioned problem by providing a rod-shaped reinforcing member provided in a hollow portion with a deformable distortion of a hollow double structure with respect to the rod-shaped reinforcing member at both ends. By holding the hollow double-walled structure through the holding member having a function of absorbing the heat, the deformation of the hollow reinforcing member during the blow-molding process is reduced by the holding member. A hollow double-walled structure that does not cause deformation distortion due to cooling shrinkage after molding, even if the strength and rigidity are improved by inserting a metal rod-shaped reinforcing member,
And a method for producing the same.

[0006]

In order to achieve the above object, a hollow double-walled structure according to the present invention comprises a front wall, a back wall opposed to the front wall at an interval, a front wall and a back wall. And a surrounding wall forming a hollow portion between the hollow wall portion and a bar-shaped reinforcing member disposed in the hollow portion, at the end of the bar-shaped reinforcing member on the back wall. The corresponding portion has a holding member that holds the bar-shaped reinforcing member to the hollow double-walled structure, and the holding member has a function of absorbing deformation distortion of the hollow double-structured structure with respect to the bar-shaped reinforcing member. It is characterized by the following.

The hollow double-walled structure according to the present invention is preferably configured as follows. That is, the periphery of the bar-shaped reinforcing member is surrounded by at least the surrounding wall integrally connected to the back wall, and the surrounding wall surrounding the periphery of the bar-shaped reinforcing member includes a part of the bar-shaped reinforcing member on the surface side of the back wall. Having a groove that is exposed, the holding member that holds the bar-shaped reinforcing member in the hollow double-walled structure, is configured to slidably insert and support the bar-shaped reinforcing member, or is formed of a material that absorbs deformation strain. That is.

In the method for manufacturing a hollow double-walled structure according to the present invention, a hollow portion is formed between a front wall, a back wall opposed to the front wall at an interval, and the front wall and the back wall. Blow molding a hollow double-walled structure composed of a surrounding wall and a rod-shaped reinforcement in which holding members are attached to both ends of a cavity of a mold forming a back wall of a pair of divided molds. It is characterized in that members are inserted and blow molded.

In the method for manufacturing a hollow double-walled structure according to the present invention, it is preferable to adopt the following means. That is, the mold cavity forming the back wall is provided with a fitting and holding mechanism for the holding member, and the holding members mounted on both ends of the rod-shaped reinforcing member are fitted and held in the mold cavity, and the holding member is provided. Is a configuration for slidably supporting the bar-shaped reinforcing member, and the holding member has a positioning structure for the bar-shaped reinforcing member.

[0010]

1 to 4 show a hollow double-wall structure according to an embodiment of the present invention. FIG. 1 is a perspective view seen from the back side, and FIG. 2 is a part of FIG. 3 is a side view of the holding member, and FIG. 4 is a front view of the holding member shown in FIG.

FIG. 5 shows another embodiment of the present invention.
6 is an enlarged sectional view of a portion corresponding to FIG.

FIGS. 7 to 11 show blow molding of a hollow double-walled structure according to an embodiment of the present invention.
8 is an enlarged sectional view showing a state before closing the mold, FIG. 8 is an enlarged sectional view showing a state after cooling, FIG. 9 is an enlarged sectional view showing a state after cooling, and FIG. AA sectional view of FIG. 11, FIG.
FIG. 9 is a sectional view taken along line BB of FIG. 8.

In FIG. 1, reference numeral 1 denotes a hollow double-walled structure. The hollow double-walled structure 1 has a panel shape,
Reference numeral 2 denotes a front wall, 3 denotes a back wall, and 4 denotes a peripheral wall. As shown in FIG. 2, the back wall 3 faces the front wall 2 at an interval. A hollow portion 5 is formed between 2 and the back wall 3.

In the hollow portion 5 of the hollow double-wall structure 1, a bar-shaped reinforcing member 6 made of a metal pipe is disposed, and the bar-shaped reinforcing member 6 is surrounded by an enclosing wall 7 integrally connected to the back wall 3. The surrounding surface is surrounded by.

As shown in FIG. 1, holding members 8, 8 are provided at both ends of the bar-shaped reinforcing member 6 in correspondence thereto.
Both ends of the bar-shaped reinforcing member 6 are held by the surrounding wall 7 via holding members 8.

As shown in FIGS. 2 to 4, the holding member 8 is made of a foamed material, and has at one end thereof a fitting projection 9 for fitting into the bar-shaped reinforcing member 7, and Wall 4
The side has a fitting groove 10. The fitting groove 10 is to be fitted and held in a cavity of a mold for forming the back wall 3 among blow molds, as described later.

Since the holding member 8 is made of a foam material and is freely deformable, it has a function of absorbing the deformation distortion of the hollow double structure 1 with respect to the bar-shaped reinforcing member 6. The foam material forming the holding member 8 is urethane foam or the like.

FIGS. 5 and 6 show another embodiment of the present invention. In this embodiment, the holding member 8 is configured to slidably insert and support the bar-shaped reinforcing member 6. That is, reference numeral 11 denotes an insertion hole portion of the rod-shaped reinforcing member 6, and the rod-shaped reinforcing member 6
1 and is slidably supported in the longitudinal direction.
The holding member 8 has a fitting groove 10 for fitting and holding in a cavity of a mold for forming the back wall 3 of a blow-molded split mold as described later. It has ridges 12,12.

In this embodiment, since the bar-shaped reinforcing member 6 is slidable with respect to the holding member 8, the effective length of the bar-shaped reinforcing member 6 between the two holding members 8, 8 changes, thereby changing the bar-shaped reinforcing member. It has a function of absorbing deformation distortion of the hollow double structure 1 with respect to the member 6.

In the embodiment shown in FIG. 5, a groove 12 for exposing a part of the peripheral surface of the bar-shaped reinforcing member 6 to the outside is formed on the back wall 3 side of the surrounding wall 7.

The hollow double-walled structure 1 according to the present invention comprises AB
S resin, modified polyphenylene oxide resin, polycarbonate resin, polyamide resin, polypropylene resin,
It is made of a blowable thermoplastic resin such as a polyethylene resin. Further, the rod-shaped reinforcing member 6 is made of a highly rigid resin such as metal or engineering plastic, and is subjected to a surface treatment such as plating to improve the slipperiness of the surface if necessary. .

The hollow double-wall structure 1 according to the present invention is shown in FIG.
Or blow molding as shown in FIG. As shown in FIG. 7, reference numeral 13 denotes one split mold for molding the front wall 2;
Reference numeral 4 denotes the other split mold for molding the back wall 3, and holding members 8, 8 fitted on both ends of the rod-shaped reinforcing member 6 are fitted and held in the cavity 15 of the other split mold 14, and the rod-shaped reinforcement is provided. The member 6 and the holding members 8 at both ends thereof are inserted.
In FIG. 6, 16 is an extrusion die, and 17 is a parison.

The hollow double-walled structure 1 shown in FIGS. 1 to 4 is blow-molded by the blow-molding mode shown in FIG. Even if the hollow double-walled structure 1 is largely contracted, the contraction strain is caused by the deformation of the holding members 8 made of a foam material or the change of the effective length of the rod-shaped reinforcing member 6 which is slidably inserted and supported. The hollow double-walled structure 1 is absorbed and does not undergo deformation distortion due to cooling shrinkage.

As shown in FIG. 5, when the groove 12 for exposing a part of the peripheral surface of the bar-shaped reinforcing member 6 to the outside is formed on the back wall 3 side, At the time of disposal, it can be easily recognized that the bar-shaped reinforcing material 6 has been inserted into the hollow double-walled structure 1, and the separation can be reliably and easily performed. At this time, the hollow double-walled structure 1 can be easily split by biting the splitting tool into the groove portion 12, so that the sorting operation is further facilitated.

As shown in FIGS. 8 and 9, in the holding member 8 in which the bar-shaped reinforcing member 6 is slidably inserted and supported, the rod-shaped reinforcing member 6 is positioned on the inner surface of the insertion hole 11. An elastic needle-shaped body 18 is provided upright. When the holding members 8 and 8 are inserted into both ends of the bar-shaped reinforcing member 6, the rod-shaped reinforcing member 6 is temporarily supported by the elastic needle-shaped body 18 and positioned, and is inserted into the cavity 15 of the other split mold 14 in this state. Therefore, at the time of blow molding, the bar-shaped reinforcing member 6
In addition, the holding members 8, 8 do not shift.

Since the elastic needle-like body 18 is a thin elastic body, when the hollow double-walled structure 1 contracts with respect to the bar-shaped reinforcing member 6 by cooling after blow molding, as shown in FIG. Since the needle-like body 18 is easily bent, there is no problem in absorbing the distortion due to the cooling shrinkage.

[0027]

According to the present invention, the rod-shaped reinforcing member disposed in the hollow portion is hollowed at both ends thereof through the holding member having the function of absorbing the deformation strain of the hollow double structure with respect to the rod-shaped reinforcing member. By holding the double-walled structure, the deformation deformation of the rod-shaped reinforcing member can be absorbed by the holding member in the process of cooling and shrinking the hollow double-walled structure after blow molding, and the metal rod-shaped reinforcing member A hollow double-walled structure that does not generate deformation distortion due to cooling shrinkage after molding, even if the strength and rigidity are improved by inserting
And a method for manufacturing the same.

[Brief description of the drawings]

FIG. 1 is a perspective view of a hollow double-walled structure according to an embodiment of the present invention as viewed from the back side.

FIG. 2 is an enlarged sectional view of a part of FIG.

FIG. 3 is a side view of the holding member.

FIG. 4 is a front view of the holding member shown in FIG. 3;

FIG. 5 is an enlarged sectional view of a portion corresponding to FIG. 2 according to another embodiment of the present invention.

FIG. 6 is a perspective view of a part of FIG.

FIG. 7 is a cross-sectional view showing a blow molding mode of the hollow double-walled structure according to the embodiment of the present invention, showing a mode before closing the mold.

FIG. 8 is an enlarged cross-sectional view within a dashed circle in FIG. 7;

FIG. 9 is an enlarged cross-sectional view in a broken-line circle of FIG. 7 showing a state after cooling.

FIG. 10 is a sectional view taken along line AA of FIG. 8;

FIG. 11 is a sectional view taken along line BB of FIG. 8;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hollow double wall structure 2 Front wall 3 Back wall 4 Peripheral wall 5 Hollow part 6 Bar-shaped reinforcing member 7 Surrounding wall 8,8 Holding member 9 Fitting projection 10 Fitting groove 11 Fitting hole 12,12 Embedding Ridge 13 one split mold 14 the other split mold 15 cavity 16 extrusion die 17 parison 18 elastic needle-shaped body

Claims (7)

[Claims] 1. A hollow double-walled structure comprising a front wall, a back wall facing the front wall at an interval, and a peripheral wall forming a hollow portion between the front wall and the back wall. In addition, a rod-shaped reinforcing member is disposed in the hollow portion, and a holding member that holds the rod-shaped reinforcing member to the hollow double-walled structure is provided at a portion of the back wall corresponding to the end of the rod-shaped reinforcing member. Wherein the holding member has a function of absorbing deformation distortion of the hollow double structure with respect to the rod-shaped reinforcing member. 2. The hollow double-wall structure according to claim 1, wherein the periphery of the bar-shaped reinforcing member is surrounded by at least an surrounding wall integrally connected to the back wall. 3. The hollow space according to claim 2, wherein the surrounding wall surrounding the bar-shaped reinforcing member has a groove on a surface side of the back wall to expose a part of the bar-shaped reinforcing member. Heavy wall structure. 4. A holding member for holding the bar-shaped reinforcing member in the hollow double-walled structure, wherein the holding member is configured to slidably insert and support the bar-shaped reinforcing member, or is formed of a material that absorbs deformation strain. The hollow double-walled structure according to claim 1, 2, or 3. 5. A hollow double-walled structure comprising a front wall, a back wall opposed to the front wall at an interval, and a peripheral wall forming a hollow portion between the front wall and the back wall. A method of blow molding, wherein a rod-shaped reinforcing member having holding members attached to both ends is inserted into a cavity of a mold forming a back wall of a pair of split molds, and blow molding is performed. A method for manufacturing a heavy wall structure. 6. A holding member fitting / holding mechanism is provided in a cavity of a mold forming a back wall, and holding members attached to both ends of a rod-shaped reinforcing member are fitted and held in cavities of the mold. The method for producing a hollow double-walled structure according to claim 5, characterized in that: 7. The hollow double-walled structure according to claim 6, wherein the holding member is configured to slidably support the bar-shaped reinforcing member, and the holding member has a positioning structure for the bar-shaped reinforcing member. How to make the body.