JP2004504961A - Panel structure with rigid foam core - Google Patents

Abstract

The panel structure (10) includes a rigid foam core (30) interposed between two skin fiber layers (20, 24). The core preferably comprises polyurethane, polypropylene, polystyrene and mixtures thereof, as well as polyphenylene oxide (PPO) and blends thereof. The fiber layers (20, 24) can be a bidirectional woven fabric, a unidirectional material, a random woven mat, etc., impregnated with an epoxy or resin binder. The fibers themselves can be glass fibers, polypropylene, Kevlar, carbon fibers. The rigid foam core itself is formed from a thermoplastic polyolefin (TPO), high-density polyethylene (HDPE), acrylonitrile butadiene styrene or the like into a skin layer (20, 24) having lips (22, 26) around it. The lips (22, 26) are compressed together to form a peripheral bead or seal (28).
[Selection] Figure 2

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates generally to multilayer panel structures and methods of making the same, and more particularly, to multilayer panel structures having a rigid foam core interposed between outer plastic skins and panels and a method of making the structure. .
[0002]
[Prior art]
Conventionally, many types of plastic composite panels have been manufactured. Multiple layers of thermoplastic and thermoset materials selected from a wide range combined with various moderate reinforcement materials to provide various composites that exhibit specific structural properties for the specific application intended It has been. For example, a composite having a balsa wood material as a central layer between outer layers made of resin-impregnated cloth provides relatively light weight and good silencing characteristics, while providing extremely excellent strength and rigidity. Has been found.
[0003]
[Problems to be solved by the invention]
A disadvantage of many such composites, especially those composed of only plastic materials, especially thermoplastic materials, is cold flow, or creep. Cold flow (creep) is generally defined as the tendency of a structural material to gradually distort or deform under load. Although such deformations occur to a greater or lesser extent over longer periods of time, removal is generally only possible by applying an opposite load for approximately the same period of time, so that this deformation is generally permanent. Is recognized. At elevated temperatures, such as those experienced by panels and structures exposed to direct sunlight (ie, outdoors), creep (cold flow) is, of course, significantly accelerated.
[0004]
Such creep (cold flow) phenomena is a serious problem and also a drawback of many components made of thermoplastic and thermoset materials, and the existence of this problem has led to the use of said materials. It is often limited to applications that are not exposed to outdoor sunlight, a relatively high temperature environment, or a static high load environment. The present invention aims to minimize this disadvantage of these materials.
[0005]
[Means for Solving the Problems]
The panel structure according to the present invention includes two skins or panels and a central rigid core assembly. The center core assembly is a sandwich having a foam (hereinafter referred to as a foam) center layer surrounded by an upper resin impregnated fiber layer and a lower resin impregnated fiber layer. The central core can be formed from a variety of materials, but is preferably a rigid foam such as polyurethane, polypropylene, polystyrene, mixtures thereof, and polyphenylene oxide (PPO) and blends thereof. The fiber layer can be a bidirectional woven fabric, a unidirectional material, a random woven mat, etc., impregnated with an epoxy or resin binder. As the fiber itself, glass fiber, polypropylene, Kevlar, or carbon fiber can be used. The rigid foam core sandwich is made of an upper skin (panel) made of a moldable thermoplastic material such as thermoplastic polyolefin (TPO), high density polyethylene (HDPE), acrylonitrile butadiene styrene (ABS), which can be molded with a high quality exterior surface finish. ) And the lower skin (panel). The properties of the outer surface may be smooth, textured, simulate a granular appearance, or may have any other desired surface finish. A paint can be applied to the outer surface as desired.
[0006]
The method of manufacturing the panel structure is also part of the present invention. The method comprises the steps of providing an upper mold and a lower mold having a shape corresponding to the final product shape, and placing a first heated planar sheet of material such as TPO, HDPE, ABS, etc. on the lower mold. And vacuum forming it. An adhesive is applied to both surfaces of the previously prepared rigid foam core assembly and placed inside the first cast panel. Next, a second heated planar sheet material is placed adjacent to the upper mold and vacuum formed. Both molds are aligned and the mold and molded panel are brought together. By compressing the edges of both skins (panels) together, an adhesive or seal is created spontaneously at the edges of the panel structure. Thereafter, the panel structure is removed from the mold and excess material is removed from the periphery of the panel structure.
[0007]
Products incorporating these features and / or manufactured by the method of the present invention are suitable as cargo covers and tonneau covers for light trucks and pickup trucks, as well as for vehicle flooring, truck beds, tail boards, etc. It is suitable for other applications requiring panels with good strength, stiffness, dimensional stability and creep resistance.
[0008]
Accordingly, it is an object of the present invention to provide a panel structure having a rigid foam core.
[0009]
It is a further object of the present invention to provide a panel structure having a skin (panel) with a smooth, non-smooth or painted outer surface and a foam core disposed therein.
[0010]
It is a further object of the present invention to provide a panel structure having an outer panel (skin) surrounding an inner rigid foam core assembly.
[0011]
It is a further object of the present invention to provide a plastic panel structure having a rigid foam core that exhibits good creep resistance.
[0012]
It is a further object of the present invention to provide a method for manufacturing a panel structure.
[0013]
Further objects and advantages of the present invention will become apparent by reference to the preferred embodiments described below and the accompanying drawings. In the drawings, the same reference numeral indicates the same component, element, or feature.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
1, 2, and 3, the entire panel structure according to the present invention is indicated by reference numeral 10. The panel structure 10 of FIG. 1 is configured as a rigid tonneau cover that is disposed on and protects the luggage loading area 12 of a bed 14 of a conventional pickup truck 16. Further, the panel structure 10 is used for vehicle flooring, truck beds, tail boards, body panels, doors, and many other components for vehicles and non-vehicles.
[0015]
As shown in FIG. 2, the panel structure 10 includes a first (or upper) outer skin (or panel) 20 having a folded or downwardly bent end or lip 22 and a folded or upper surface. And a second (or lower) outer skin (or panel) 24 having a bent end or lip 26. The lips or ends 22 and 26 merge and their periphery is sealed with a bead or seal 28. The upper panel 20 and the lower panel 24 are preferably formed of a thermoplastic or thermosetting material such as thermoplastic polyolefin (TPO), high density polyethylene (HDPE), acrylonitrile butadiene styrene (ABS). A rigid foam core assembly 30 is disposed between the upper skin (panel) 20 and the lower skin (panel) 24 as shown in FIG.
[0016]
The rigid foam core assembly 30 includes a central core 32 of a rigid material such as aluminum honeycomb, polyurethane foam, polypropylene foam, polystyrene foam, as well as a dimensionally stable rigid material such as a blend of polystyrene, polyphenylene oxide, and other materials. The rigid foam core assembly 30 also includes an upper surface layer 34 and a lower surface layer 36, which are preferably layers of fibers impregnated with an epoxy or resin binder, wherein the fibers are woven. Bidirectional woven fabric consisting of layers of fibers comprising or interlaced alternately; unidirectional fibers; or randomly woven materials, such as glass fibers, polypropylene, Kevlar, carbon fibers , And other materials can be used. Kevlar I. duPont is a trademark of DeNemours.
[0017]
Typically, the rigid foam core assembly 30 is between 0.5 inches (12.5 mm) and 1.5 inches (38.2 mm) thick, but may be thinner or thicker, and The total thickness is between about 0.75 inches (19.1 mm) and 2.0 inches (50.8 mm).
[0018]
FIG. 4 shows a method for manufacturing the planar structure 10. A lower mold section 40 is provided having a conventional vacuum mold surface 42 that defines an inverted surface with the final desired lower surface of the panel structure 10. The vacuum mold surface 42 may be smooth, may be textured, or may define a surface that mimics irregularities such as stones or wood, or may define other desired patterns. The lower mold section 40 includes a continuous end (or rim) 44 with a raised peripheral edge. The lower mold portion 40 also includes a plurality of relatively narrow passages 46 that extend through the lower mold portion 40 from the lower mold space 48 to a vacuum plenum 52 defined by a chamber or outer wall 54. are doing. The outer wall 54 is sealed and fixed to the back of the lower mold part 40 as shown. The first vacuum pump 56 is in communication with the lower vacuum plenum 52 and, when activated, depressurizes the lower vacuum plenum 52 and draws air through the small passage 46.
[0019]
The lower skin (lower panel) 22 is provided to the lower mold part 40 at an elevated temperature. As used herein, "elevated temperature" refers to the temperature at which a particular material is sufficiently flexible to be vacuum formable but not so flexible as to prevent or disable vacuum forming. Means range. Such elevated temperatures are achieved by exposing the lower panel 22 to, for example, infrared radiation or heated circulating air to heat it. Alternatively, the lower panel 22 may be quickly utilized after being extruded from a molding station (not shown) and before cooling. The lower panel 22 is transferred to the mold space 48 and is placed over the mold space 48 by the peripheral support frame 58. Next, the vacuum pump 56 is operated.
[0020]
When the plenum 52 and mold space 48 are depressurized over a suitable period of time, as shown in FIG. 5, the lower panel 22 is drawn into the lower mold space 48 and conforms to the vacuum mold surface 42 of the lower mold space 48. .
[0021]
Referring to FIG. 6, the rigid foam core assembly 30 is a composite structure prepared in advance, and is preferably supplied to the lower mold part 40 in a ready-to-use state. Before placing the foam core assembly 30 in the cast lower panel 24 located in the lower mold space 48 of the lower mold section 40, an adhesive 62 is applied to both flat surfaces of the foam core assembly 30. . Adhesive 62 is preferably compatible with the material used to fabricate planar structure 10 and may be applied by spray head 64 or other means such as rollers, brushes, baths (all not shown), and the like.
[0022]
Referring to FIG. 7, there is also provided an upper mold section 70 having a conventional vacuum mold surface 72 that defines a surface having the inverted topography and concavity and convexity of the final desired top surface of the panel structure 10. The vacuum mold surface 72 may be smooth, textured, or define a surface that mimics irregularities such as stones or wood, and may define other desired patterns. The upper mold section 70 includes a continuous end (or rim) 74 with a raised peripheral edge. The upper mold section 70 also includes a plurality of relatively narrow passages 76 that extend through the upper mold section 20 from the upper mold space 78 to a vacuum plenum 82 defined by a chamber or outer wall 84. are doing. The outer wall 84 is sealed and fixed to the back of the upper mold part 70 as shown. A second vacuum pump 86 is in communication with the upper vacuum plenum 82 and, when activated, depressurizes the upper plenum 82 and draws air through the small passage 76.
[0023]
The upper skin (upper panel) 20 is provided to the upper mold part 70 at an elevated temperature. As noted above, such elevated temperatures are achieved by exposing the upper panel 20 to, for example, infrared radiation or heated circulating air to heat it. Alternatively, the upper panel 20 may be quickly utilized after being extruded from a molding station (not shown) and before cooling. The upper panel 20 is transported to the end (rim) 74 of the upper mold part 70 and is placed adjacent to the end (rim) 74 of the upper mold part 70 by the peripheral support frame 88. Next, the second vacuum pump 86 is operated.
[0024]
As shown in FIG. 8, when the pressure is reduced for a suitable time, the upper panel 20 is drawn into the upper mold space 78 and takes a shape along the vacuum mold surface 72 of the upper mold space 78.
[0025]
Referring to FIG. 9, the upper mold part 70 containing the upper skin (upper panel) 20 is placed on the lower mold part 40 containing the lower skin (lower panel) 24 and the rigid foam core assembly 30, and The mold 70 is moved to the position shown in FIG. 9 so that the ends (i.e., rims 44 and 74) of each mold section 40 and 70 press against the ends of the upper panel 20 and the lower panel 22, thereby forming the panel structure. A seal 24 is formed around body 10.
[0026]
Finally, the mold parts 40 and 70 are separated from each other, and the panel structure 10 is taken out. A burr 90 is typically formed, which is easily removed by sawing, polishing, grinding or sanding after the panel structure 10 has been removed from the mold sections 40 and 70. The manufacture of the panel structure 10 according to the present invention is now completed.
[0027]
It will be appreciated that the panel structure 10 configured, for example, as a tonneau cover exhibits excellent stiffness, surface finish, and creep resistance. The outer surfaces of panels 20 and 24 can be finished very smoothly, comparable to the finish of metal panels, and are easy to paint. Alternatively, as noted, the finish may be patterned, grained, or grained by appropriate treatment of the vacuum mold surfaces 42, 72 of mold sections 40, 70.
[0028]
The above disclosure is the best embodiment created by the inventors to carry out the invention. However, it will be apparent that various modifications and variations of the present apparatus and method will be apparent to those skilled in the art of panel structures and methods of manufacturing panel structures. Since the above disclosure provides the best mode contemplated by the inventors for carrying out the invention, and is intended to enable anyone skilled in the art to practice the invention, the present invention It should not be construed as limited by the above disclosure, but should be construed to include the obvious variations etc. described above and should be limited only by the spirit and scope of the following claims.
[Brief description of the drawings]
FIG.
1 is a perspective view of a panel structure used as a tonneau cover of a pickup truck according to the present invention.
FIG. 2
FIG. 2 is a partial cross-sectional view of the panel structure according to the present invention taken along line 2-2 in FIG.
FIG. 3
It is a fragmentary sectional view of a rigid foam core assembly of a panel structure concerning the present invention.
FIG. 4
FIG. 3 is a cross-sectional view of the entire lower vacuum forming mold used in manufacturing the panel structure according to the present invention, showing a state where a lower outer skin (lower panel) is at a predetermined position on the lower mold before forming.
FIG. 5
It is sectional drawing of the whole lower vacuum forming mold provided with the lower panel where the panel structure which concerns on this invention was formed.
FIG. 6
FIG. 3 is a cross-sectional view of the entire lower vacuum forming mold with a molded lower panel and a rigid foam core assembly disposed on the molded lower panel.
FIG. 7
FIG. 4 is a cross-sectional view of the entire upper vacuum forming mold used in manufacturing the panel structure according to the present invention, in which an upper outer skin (upper panel) is at a predetermined position on the upper mold before forming.
FIG. 8
It is sectional drawing of the whole upper vacuum forming mold provided with the molded upper panel of the panel structure which concerns on this invention.
FIG. 9
FIG. 5 is a cross-sectional view of the entire vacuum forming mold containing the upper panel and the lower panel in a state surrounding the rigid foam core assembly in a final step of manufacturing the panel structure according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Panel structure 22, 26 Lip 20, 24 Panel 28 Seal 30 Rigid foam core assembly 40 Lower mold part 44, 74 Rim 46, 76 Small passage 48, 78 Mold space 58, 88 Peripheral support frame 62 Adhesive 70 Upper mold Part 70

Claims (20)

A panel structure having a combination of a first panel having a central flat portion and a peripheral lip portion; a second panel having a central flat portion and a peripheral lip portion; and a rigid core,
The first and second panels are sealed at the peripheral lip to define an interior space;
The rigid core is disposed in the internal space and substantially fills the space, and includes a central layer having an opposing flat surface and first and second fiber layers fixed to the opposing flat surface. A panel structure. The panel structure according to claim 1, wherein the material of the first and second panels is selected from the group consisting of high-density polyethylene, thermoplastic polyolefin, and acrylonitrile butadiene styrene. The panel structure according to claim 1, wherein the structure is a tonneau cover. The panel structure according to claim 1, wherein a material of the central layer made of the rigid core is selected from the group consisting of aluminum honeycomb, polyurethane foam, polypropylene foam, and polystyrene foam. The panel structure according to claim 1, wherein the first and second fiber layers are a woven fabric layer, a unidirectional fiber layer, or a random fiber layer. The composite of claim 1, wherein the first and second fiber layers include an epoxy or resin binder. The panel structure according to claim 1, further comprising an adhesive layer disposed between the rigid core and the first and second panels. A first outer panel having a first flat portion and a first peripheral lip; a second outer panel having a second flat portion and a first peripheral lip; and a core in combination A panel structure,
The first and second panels are sealed at the peripheral lip to define an interior space;
The core is disposed in the interior space, substantially fills the space, and has a central layer having a substantially parallel flat surface and a first layer fixed to each of the opposed flat surfaces. A panel structure having a second fiber layer. 9. The panel structure of claim 8, wherein the panel material is selected from the group consisting of high density polyethylene, thermoplastic polyolefin, and acrylonitrile butadiene styrene. 9. The panel structure according to claim 8, defining a tonneau cover. 9. The panel structure of claim 8, wherein the material of the central layer comprising the core is selected from the group consisting of aluminum honeycomb, polyurethane foam, polypropylene foam, polystyrene foam, and a blend of polystyrene and polyphenylene oxide foam. body. The panel structure according to claim 8, wherein the first and second fiber layers are a woven fabric layer, a unidirectional fiber layer, or a random fiber layer. The composite of claim 8, wherein the first and second fiber layers include an epoxy or resin binder. The panel structure according to claim 8, further comprising an adhesive layer disposed between the core and the first and second panels. Providing an upper vacuum mold and a lower vacuum mold;
Providing a first heated panel of a moldable plastic material to the lower mold and vacuum forming the first panel;
Providing a preformed core having a central region and an outer fibrous layer; applying an adhesive to the outer fibrous layer;
Placing the rigid core within the molded first panel;
Providing a second heated panel of a moldable plastic material to the upper mold and vacuum forming the second panel;
Disposing the upper mold adjacent to the lower mold and sealing the first and second panels together to define a peripheral seal. The method of claim 15, further comprising removing excess material adjacent the peripheral seal. The method of claim 15, wherein the adhesive is applied by spraying the outer surface layer. The method of claim 15, wherein the panel is utilized after extrusion and before cooling. The method of claim 15, wherein the panel is a thermoplastic olefin. 16. The method of claim 15, wherein said panel is high density polyethylene.