MXPA00009250A - Reinforcement laminate - Google Patents

Abstract

A tri-laminate body panel stiffener (4) includes two polymer layers (5, 6) with or without abacking (7). One of the layers is a compliant foam layer (5) mounted against a substrate (1) while the other layer is a rigid foam layer (6) mounted against the compliant foam layer (5). In another aspect of the invention the laminate comprises a backing member having an expandable foam mounted thereto with two or more edges of the laminate being of non-straight construction such as being wavy orsaw tooth. A pattern of holes may be formed through the foam and backing layers.

Description

REINFORCEMENT LAMINATE BACKGROUND OF THE INVENTION The traditional practice for tightening outer panels of automobile bodies is with a thermoset lamellar polymer placed inside the panel and then cured by heating in a paint oven. The traditional heat cured stiffener is placed as a wallpaper-type application or as a spray on a layer. The application is provided in single or double layer sheets. The main layer is a thermostable layer with or without backing. Where the backrest is used, the backing can be fiberglass cloth, metal mesh or sheet metal. The spray is a simple polymeric layer without backing. The polymeric layer is generally 0.020 to 0.100 inches thick. In the automotive industry, when vehicle doors are painted from the surface, there is a problem with the paint marks due to the heat cure of the external panel stiffener in the metal body and the expansion and contraction of the metallic outer panel during the baking cycle Of paint. It would be desirable if some techniques were provided to eliminate or reduce the problem of paint marks.

SUMMARY OF THE INVENTION An object of this invention is to provide a body panel stiffener that improves upon traditional practices. Another object of this invention is to eliminate the darkening of the paint or distortion of the metal by reducing the shrinkage efforts of curing during polymer curing and curing of the metal panel. Still another object of this invention is to provide such techniques that are particularly adaptable for the automotive industry. In accordance with one aspect of this invention, a laminated reinforcement or stiffener is provided for a body panel which includes two polymeric layers mounted against a substrate with or without a backing. Preferably, one of the polymer layers is a flexible foam that would be placed directly against the substrate or the structural member being reinforced. A layer of external or rigid foam is secured on the other side of the flexible foam layer and a carrier, such as a sheet or fiberglass as a backing is secured to the outer surface of the rigid foam layer. In accordance with another aspect of this invention, the reinforcing laminate for a part or substrate is made of a stiffening element or backing having an expandable foam secured thereto. According to the invention, the marks are controlled by different alternative techniques. For example, the mark can be controlled by not having parallel longitudinal edges. This can be obtained by having undulating and / or serrated conditions on two and / or four opposite edges. Another technique for controlling the marks would be the thickness of the polymeric material and the perforation or formation of holes through the entire polymer and backing layers. The pattern of the holes may be ordered or uniform or may be in a staggered or random presentation.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 and 2 are cross-sectional elevational views of the prior art stiffeners; Figure 3 is a cross-sectional elevation view of a trilaminate stiffener for body panel according to this invention. Figure 4 is a perspective view showing the stiffener of Figure 3 used for application to automobile doors. Figures 5-7 are cross-sectional views of different configurations based on section AA of Figure 4. Figure 8 is a side elevational view showing the interior of a vehicle door having a reinforcement laminate mounted thereto in accordance with another aspect of this invention; Figure 9 is a cross-sectional view taken through Figure 8 along line 9-9; Figure 10 is a front elevational view of a form of reinforcing laminate; and Figure 11 is a view similar to Figure 10 of a modified form of reinforcement laminate.

DETAILED DESCRIPTION OF THE INVENTION Figures 1-2 illustrate traditional practices for reinforcing external body panels for automobiles. As shown therein, a metal substrate 1 is provided on which the polymer 2 is bonded. The application of the polymer 2 which can be a lamellar thermosetting polymer can be by the use of a wallpaper type technique as shown in the Figure 1 or can be sprayed as shown in Figure 2. In practice as shown in Figure 1, a fiberglass backing 3 covers the polymer 2. After the polymer 2 is applied then it is cured with heat in an oven. When using a wallpaper type application, it is possible to apply single or double layer sheets. The main layer would be a thermosetting layer with or without backing. In the alternative of Figure 2, a single polymer layer without backing is applied. Where the backrest is used, the backing can be fiberglass cloth, metal mesh or sheet metal. In general, the polymer layer would have a thickness of 0.020 to 0.100 inches thick. Traditional panel stiffeners such as those shown in Figures 1 and 2 shrink when cured. Due to its good adhesion, shrinkage curing efforts are fed to the substrate 1 to which the stiffener is attached. Consequently, the paint on the opposite side of the substrate 1 would form patterns according to the stresses induced in the substrate. Figure 3 illustrates a stiffener 4 in accordance with this invention. As shown therein, a flexible foam layer 5 is applied directly against the metal panel or substrate 1. A layer of rigid foam 6 is applied against the flexible foam layer 5. Figure 3 also illustrates a sheet metal backing or carrier or fiberglass 7 on the outer surface of the rigid foam layer 6. This gives rise to a trilaminate stiffener for body panel 4. When the trilaminate stiffener 10 is cured, the first intimate layer 5 can not transfer the shrinkage efforts to the substrate 1 and the layer 5 can not restrict the shrinkage of the external metal panel when the panel leaves the oven because it is not rigid after curing.

The second layer 6 is rigid after curing, but its shrinkage force is blocked from reaching the substrate by the first flexible layer. The backing or carrier 7 is used to provide additional stiffness. The flexible foam layer 5 absorbs the shrinkage forces due to the curing of the heat-sensitive layers. The large contraction forces of the rigid layer 6 are not fed to the metal substrate 1, but still the rigid layer 6 with its back 7 will stiffen the panel. The common layer thicknesses are from 1-1.5 mm for the flexible layer 5 and from 1-2.0 inches for the rigid layer ß with the backing layer 7 having a thickness of 0.002-0.004 inches. It is possible to use any suitable material for layers 5 and 6. Both polymeric layers must be compatible in chemistry, however, otherwise the finished product will cure the layer will be compromised. Reference is made to my United States Patent No. 5,575,526 and to my serial application No. 09 / 099,025, filed on June 17, 1998, all the details of which patent and application are incorporated herein by reference thereto. The patent and application describe suitable materials that can be used for the foam layer to create a rigid structural foam and materials for the carrier. The specific materials are not crucial provided that they work in the manner proposed, namely, that layer 5 would be flexible while layer 6 would have rigidity. The flexible layer 5 may have rubber-like characteristics as traditionally used materials for refrigerator test seals or strips for automobile doors. The layer 5 can be sticky or non-sticky. Figure 4 illustrates the lamination of sheet metal backing 4 of this invention as it is used for application to automobile doors. Figures 5-7 illustrate in a cut different possible configurations for such applications. As is evident from Figures 3 and 5, the stiffener of the tripolytic layer 4 can be uniform thickness with the flat, smooth layers as illustrated in Figure 3. Figure 5, however, illustrates a door panel 1 with a shallow curved configuration. The patch or stiffener 4 will conform this configuration. Figure 5 shows the stiffener 4 with uniform thickness. Figures 6-1, however, show variations that could be incorporated which require non-uniform thicknesses. As shown, the backing or sheet metal carrier 7 includes an outer channel section 7A forming a rib or bead in combination with the extended portion 8 of the foam layers 5, 6. The foam layers 5, 6 would be provided as two. pairs of separate sheets that abut contact each other or are spliced into the channel section 7A. For example, Figure 6 shows the two foam layers 5 spliced together on the surface 5A. The sheet metal backing 7 can also be made of two layers that are joined at the center of the channel 7A. Figure 7 shows end extensions or flanges 7B of the sheet metal back 7 with the end flanges in conformation 9 for the pair of foam layers 5, 6 in combination with a central extension 7C of the sheet metal back 7 and a central extension 9A of the layers of foam 5, 6 to accommodate a flange 1A in the panel 1. The arrangement of these extensions outward gives rise to flange sections which offer further stiffening of the panel compared to a completely flat and / or uniform laminate due to the increase in the section and redistribution of the laminated reinforcement supported by sheet metal away from the neutral axis of the panel. Thus Figures 6-7 illustrate the stiffener 4 including the reinforced edges while Figure 7 also includes end reinforcement flanges. Figures 8-11 refer to paint marks that cause metallic shading or distortion. The techniques included in Figures 8-11 can be used in combination with the trilaminate structure of Figures 3-7 or can be used separately from these characteristics. In general, the invention illustrated in Figures 8-11 includes providing a laminated stiffener or laminated reinforcement for a substrate part. The laminate materials and the substrate to which it would be applied and the uses of the invention may be those described with respect to Figures 3-7. As shown in Figures 8-9, the part or substrate 10 being reinforced is a vehicle door. A reinforcing laminate 12 is mounted to the door preferably generally in the central area of the door. The lick can be any size and shape. In the preferred embodiment, the laminate is of generally rectangular shape having certain modifications that will be described later. The laminate 12 consists of a backing 14 and an intimately bonded expandable foam layer 16. The foam layer 16 may be a single layer of rigid structural foam as in my patent and application noted above or may be of two layers as illustrated, for example, in Figure 3. The layer 16 is located against the substrate 10. Where the invention is used in the automotive industry, Figure 9 shows schematically a paint spray nozzle 18 applying a paint pattern 20 for creating a layer of paint 22 on the substrate 10. Where the part 10 is in a paint oven in which the polymer 16 is cured, there may be a problem with the paint markings of the body stiffeners of the external heat-sealed metal panel . The present invention provides various techniques for removing or reducing such paint marks. Figure 10 illustrates a practice of the invention where the laminate has a pair of longitudinal side edges 26, 26 interconnected by a pair of transverse end edges 24, 24. As shown in this, the opposite extreme edges 24,24 are of non-straight linear configuration forming hills and valleys. Specifically, in the modality illustrated in Figure 10, the edges 24,24 are of toothed construction. The intermediate edges 26, 26 are illustrated as being straight edges parallel to each other. However, it should be understood that the edges 26, 26 may also be non-straight in shape as having a toothed construction so that all four edges have peaks and valleys. Otherwise, the edges 26, 26 may have the toothed construction and the edges 24, 24 may be parallel, straight edges. Figure 11 illustrates a variation where the longitudinal edges 28, 28 have peaks and valleys being wavy or sinuous. The intermediate edges 30, 30 are illustrated as being parallel and straight. However, the invention can be practiced in the same way where the edges 30, 30 are also of corrugated construction similar to the edges 28, 28 or where 3, a corrugated construction is on the edges 30, 30, but the edges 28, 28 be straight and parallel. Figure 8 illustrates another possibility of the serrated edges 24 and the corrugated edges 28. Thus, any peaks and valleys creation arrangement can be used within the broad practices of this invention which includes different forms of structure to obtain peaks and valleys. valleys along the different banks. According to another practice of the invention, the markings are controlled by the thickness of the polymeric material or by drilling or otherwise forming holes through the entire polymer and backing layers. The figure, for example, shows a pattern of holes 32 in a uniform or ordered arrangement where all the holes are arranged in straight rows and columns in line with each other. However, Figure 11 shows the holes 34 in rows and straight columns that are staggered. The invention can also be practiced where the holes are in a random pattern, instead of rows and straight columns. Where the holes are provided through the laminate 12, the laminate may optionally include the non-straight edges such as the serrated and crimped formations or optionally the laminate may have some or all of the straight edges. The invention can be practiced by forming the backing layer 14 of the desired shape that includes non-straight edges. The unexpanded polymer or foam may then be covered or otherwise applied to the entire surface of the backing 14 to form the laminate 12. The laminate 12 would then be mounted to the substrate 10 by placing the polymeric layer 16 against the substrate 10. When activated the polymer, the foam expands and would move the backing layer 14 away from the substrate 10. the foam would also expand outwardly beyond the edges of the backrest 14. The different techniques used to practice the invention would lead to the reduction or elimination of metallic paint or distortion shading by reducing the shrinkage stresses during polymer curing. Although the invention is preferably practiced with a heat-expandable polymer, the invention can also be practiced with other types of expandable polymers, such as those chemically activated as in the aforementioned application. Although the invention has been particularly described with respect to its preferred use for reinforcing doors for vehicles, the concept of the invention can be applied to reinforce other parts. For example, the invention can be used for roofs, tire covers and vehicle fenders. The invention can also be used to reinforce parts other than vehicles. Likewise, although the invention is preferably practiced to support a metallic substrate, it is possible to use other substrates as described in the above-mentioned applications. The backrest 14 is preferably a thin sheet metal such as an aluminum sheet. The invention can be practiced, however, with other backing materials as described in the above-mentioned applications. The arrangement of various techniques for controlling paint marks can be incorporated into stiffener reinforcements and include the added features of the above-mentioned applications or that are simply part of a basic structure containing a backing and foam laminate. The different features described in detail herein may be used in combination with each other or separately from one another and may also be used in combination with the features described in my Copending Application Series No. 09/099, 025.

Claims (25)

1. A reinforcing laminate for reinforcing a substrate consisting of a carrier layer, a layer of rigid reinforcing foam secured to the carrier layer, a layer of flexible foam secured to the rigid foam, the layer of the flexible foam consisting of a layer of joining to secure the laminate to a substrate, the rigid foam layer and the flexible foam layer being heat-curable, and the flexible foam layer consisting of the means for absorbing the shrinkage stresses due to the heat-curing of the foam layer and cooling of the substrate.

2. The laminate of claim 1, wherein the carrier layer is a sheet backing.

3. The laminate of claim 1, in combination with the substrate, and the flexible foam being intimately bonded to the substrate.

4. The laminate of claim 3, wherein the foam layers and the carrier layer include at least one flange. The laminate of claim 4, wherein the substrate includes a flange in line with the flange of the foam layers and the carrier layer. 6. The laminate of claim 5, wherein the foam layers and the carrier layer include end flanges. The laminate of claim 3, wherein the substrate is a vehicle part selected from the group consisting of: a door, a roof, a cover lid and a fender. The laminate of claim 1, wherein the laminate has a pair of longitudinal side edges interconnected by a pair of transverse end edges and at least the pair of side edges or the pair of end edges is non-straight and undulating. 9. The laminate of claim 8, wherein the wavy shape has a pattern of hills and valleys joined together in a pattern of smooth undulations. 10. The laminate of claim 8, wherein the wavy shape has a pattern of hills and valleys in a serrated shape. 11. The laminate of claim 8, wherein the edges are not straight and corrugated are the lateral edges. 12. The laminate of claim 8, wherein the edges are not straight and corrugated end edges. 13. The laminate of claim 12, wherein the side edges are also non-straight and corrugated. 14. The laminate of claim 8, which includes a pattern of holes completely through the laminate. 1

5. The laminate of claim 14, wherein the hole patterns consist of a plurality of rows and columns of holes aligned in uniform and equal spaces. 1

6. The laminate of claim 14, wherein the hole pattern consists of a plurality of holes arranged in staggered rows and columns. 1

7. The laminate of claim 14, wherein the hole pattern is arranged randomly. 1

8. The laminate of claim 8, in combination with the substrate, and the flexible foam layer being intimately bonded to the substrate. 1

9. The laminate of claim 18, wherein the substrate is a car door. 20. The reinforcement laminate for reinforcing a substrate comprises a carrier layer, an expandable foam layer intimately bonded to the carrier layer to form a reinforcement unit, the reinforcement unit having a pair of longitudinal side edges interconnected by a pair of edges. transverse ends and at least one of the pair of lateral edges or that of extreme edges being not straight and undulating. The laminate of claim 20, wherein the wavy shape has a pattern of hills and valleys joined together in a smooth wavy pattern. 22. The laminate of claim 20, wherein the wavy shape has a pattern of hills and valleys in a serrated shape. 23. The laminate of claim 20, wherein the edges are not straight and corrugated are the lateral edges. 24. The laminate of claim 20, wherein the edges are not straight and undulated "are the extreme edges. 25. The laminate of claim 20, where the lateral edges are also not straight and undulating. 26, The laminate of claim 20, which includes a pattern of holes completely through the laminate. 27. The laminate of claim 26, wherein the hole pattern comprises a plurality of rows and columns of holes aligned uniformly and equally spaced apart. 28. The laminate of claim 26, wherein the hole pattern consists of a plurality of holes arranged in staggered rows and columns. 29. The laminate of claim 26, wherein the hole pattern is arranged randomly. 30. The laminate of claim 20, in combination with the substrate, and the foam layer being intimately bonded to the substrate. 31. The laminate of claim 30, wherein the substrate is a car door.