MXPA98005530A - Mampara estructural lamin - Google Patents

Abstract

The present invention relates to: A hollow reinforced structural member has a screen having a thermally expanded resin layer disposed between opposing side walls. A sleeve is retained within the resin layer and is oriented perpendicular to the longitudinal axis of the reinforcing structural member. The sleeve is in alignment with bolt holes on opposite sides of the reinforced structure so that a bolt can be inserted through it. A component can then be screwed to the reinforced structural member at the reinforcing site. The invention not only increases the strength of the part, but also reduces the transmission of vibration and noise.

Description

LAMINATED STRUCTURAL MAMPARA Reference to Related Request This application is based on provisional application Serial No. 60 / 053,118, filed July 18, 1997 Background of the Invention Particularly in automotive applications, box sections such as main body rails are subjected to considerable tension forces where the cross members are bolted to the rails. For example, when the engine mounts are bolted to main body rails they produce seals that are susceptible to cracking for durability over time. In addition, the bolts holding these components in place can loosen due to vibration in the joint. Additionally, conventional structures create a "noise path" that extends from the vehicle and engine wheels through the bodywork and into the passenger compartment. As will be appreciated by those skilled in the art, in order to screw a heavy component to the side of a rail section, it is necessary to create a reinforced region or support structure at the pin fixing site. One approach that is used in the art is to provide a stamped screen that supports a metal bushing. The screen generally has three flange portions that are welded in points to the rail section C. More specifically, the patterned screen has a wall portion extending from a wall of the rail section to the opposite wall or cover. In this way, the screen forms a division in the channel or cavity defined by the rail. In order to secure this wall portion in place, the screen has three surfaces or tabs that are perpendicular to the screen wall portion; that is, the screen is essentially a shallow rectangular box that is open on one side. These three surfaces coincide with the internal surfaces of the rail and are welded in place in points. In order to use the screen as a support for the transverse structure that is fixed to it, it is designed to place a metal bushing that is welded by spots to the screen print. Then a bolt passes through the bushing and secures the transverse structure to the rail in the reinforced bulkhead region. This conventional approach will be illustrated more fully below.

Even though the conventional bulkhead design serves to reinforce the rail section at the cross member fixing site, it generally requires large bore bushings and stamps and actually increases vibration and unwanted noise. Additionally, the through bolt, bushing, metal stamping and rail section essentially operate with discrete elements rather than a integral, unitary reinforcing structure. This results not only in the aforementioned increase in vibration and noise, but also fails to provide full reinforcement of the rail, resulting in metallic fatigue in the joint, and in particular, in welding locations. The present inventor has developed a number of approaches to the reinforcement of hollow metal parts such as: a reinforcement beam for a vehicle door comprising a metal member of open channel shape having a longitudinal cavity that is filled with a base material of thermosetting or thermoplastic resin; a hollow torsion bar cut to length and loaded with a resin-based material; a pre-molded reinforcement insert for structural members that is formed of a plurality of granules containing a thermosetting resin with a blowing agent, a pre-molded member that expands and cures in place in the structural member; a composite door beam having a resin-based core that occupies no more than a third of the perforation of a metal tube; a hollow laminated beam characterized by a high ratio of hardness to mass and having an external portion that is separated from an inner tube by a thin layer of structural foam; a beam reinforcement member in and comprising a pre-reinforced structural insert having an external foam which is then inserted into the hollow structural member; and a metal-shaped bracket serving as a carrier for an expandable resin that is foamed into place in a hollow section. None of these prior approaches, however, specifically deals with solving the problems associated with conventional reinforcing screens in rail sections at the cross member fixing sites. The present invention solves many of the problems inherent in the prior art. An object of the present invention is to provide a reinforced, hollow metal structure incorporating a bushing and a stamping in a partition structure in a manner in which the components of the partition work together as an integral unit with the reinforced structure.

A further object of the invention is to provide a reinforced metal box section that provides greater strength to the section without significantly increasing the vibration and noise transmission levels. A further object of the present invention is to provide a reinforced body rail section in the attachment of a transverse member such as a motor support in a manner in which the tension forces are distributed through a region of the reinforced rail in Instead of discrete welds where noise and vibration are damped. These and other objects and advantages of the invention will be more fully appreciated in accordance with the detailed description of the preferred embodiments of the invention and the drawings.

SUMMARY OF THE INVENTION In one aspect, the present invention provides a reinforced structure. The reinforced structure includes a hollow structural member and a reinforcing member disposed therein. The reinforcing member has a pair of opposite walls. A thermally expanded polymer layer is disposed between and bonds to the opposite walls. This polymer layer is also directly linked to the structural member. A sleeve extends through the polymer parallel with and between the opposite walls. The polymer is linked to the sleeve and the sleeve defines a passage through the polymer. The reinforced structure has holes that are in alignment with the ends of the sleeve. A bolt is then used to secure a component to the structural member. In this manner, the hollow structural member is locally reinforced in the present invention in that position in view of the reinforcing member. The polymer expands in place by heating the entire structure after assembly, where it expands to fill in the spaces between the reinforcing structure and the structural member and places the reinforcing structure to the structural member. In another aspect, the reinforced structure of the present invention is a motor vehicle rail such as a front rail where local reinforcement is required for the attachment of components such as a motor support. In this aspect, the invention reduces the transmission of vibration and noise as well as increases the strength of the part at the reinforcement site. In still another aspect the sleeve is a thin-walled metal bushing, the opposite walls are metal studded with flanges that are welded to the structural member and the polymer is a thermally expanded epoxy resin containing hollow microspheres for density reduction. In still another aspect, the present invention provides a method for reinforcing a structural member having a longitudinal channel. In this aspect, a laminated structure having two opposite walls separated by a layer of thermally expandable polymer is placed in the channel of a rail section or the like. The laminated structure has a sleeve disposed in the thermally expandable polymer layer. The sleeve defines a passage perpendicular to the opposite walls. The laminated structure is placed in the longitudinal channel so that the sleeve passage is perpendicular to the longitudinal channel. The laminated structure is then welded to the structural member in the flanges. The entire structure is then heated to an effective temperature to activate the blowing agent of the polymer and thus thermally expand the polymer so as to link the laminated structure to the structure member.

Brief Description of the Drawings. Figure 1 is a detailed, diagrammatic perspective view of a conventional bulkhead reinforcing structure; Figure 2 is a diagrammatic, front elevation view of the structure of Figure 1 with the cover plate removed; Figure 3 is a detailed, diagrammatic perspective view of the reinforced rail section of the present invention illustrating the construction of the laminated reinforcing screen. Figure 4 is a diagrammatic front elevational view of the structure shown in figure 3, with the lid plate removed; and Figure 5 is a diagrammatic rear view of the screen portion of Figures 3 and 4.

Detailed description. Referring now to Figures 1 and 2 of the drawings, the front rail section 20 of the prior art is shown having a section 22 in C defining the channel 23 and receiving the cover plate 24. The screen print 26 is seen to have a vertical wall 28 and flanges 30. The bushing 32 is welded to the wall 28 in a double 33 arched in the wall 28. The flanges 30 are welded to the section 22 to retain the screen 26 instead. The bolt 36 extends through the cover 24, the bushing 32 and the vertical wall 37 of the section 22 and then through a component 38 to be fastened to the rail 20. The nut 20 is then fixed to the bolt 36 to secure component 38 instead. This is representative of the prior art and suffers from the above-described disadvantages, i.e. inadequate reinforcement, problems of inadequate sound deadening and vibration. Returning to Figure 3 of the drawings, the reinforced structure 50 is shown in a form as a reinforced front rail of an automotive body and includes a C-section 52 of body rail which is closed by the cover plate 54 so that the channel or cavity 56 is defined in the reinforced structure 50. In other words, the body rail is hollow. Section 52 in C includes a vertical wall portion 58 and opposite wall portions 60 and 62. Each opposite wall portion 60, 62 has a flange portion 64 of the attachment of the lid plate 54 by welding or the like in the flange areas. The reinforcing member or screen 68 is disposed in the channel 56 of the C-section 52 and has a first wall or side 70 and a second wall or side 72. The walls 70 and 72 are parallel to each other and are separated by the polymer layer 74; that is, the polymer layer 74 is disposed between the walls 70 and 72. As best seen in Figures 4 and 5 of the drawings, each wall 70, 72 has an associated arcuate portion (76 for the wall 72 and 78 for the wall 70 = which is designed to accommodate the sleeve 81 in a manner that will be more fully described later, Each arched portion 76, 78 is approximately halfway along the length of each wall 70, 72 and can be viewed as a Curved inner surface The sleeve 81 is a metal bushing or the like and, as best seen in Figure 4 of the drawings, is welded in spots to the walls 70 and 72 at welding points 83 and 85. The layer 74 of polymer essentially envelops the sleeve 81 as shown in Figure 4. The screen 68 is secured in place in the channel 56 in view of the fixing tabs 80 and 82 extending from the walls 70 and 72 at 90's angles. That is, each wall 70, 72 has at each end a a bent portion that coincides with a similar portion on the opposite wall to form a fastening flange 80, 82 that is welded on the side wall 60, 62, respectively. The width of the walls 70 and 72 (distance between the vertical wall 58 and the lid plate 54) is such that the partition 68 is in contact with the vertical wall 58 and the cover plate 54. Consequently, the bolt 84 extends through the cover plate 54 in the hole 66, through the sleeve 81 and through a corresponding hole in the vertical wall 58 (not shown). The bolt 84 then extends through a hole in a transverse member such as a motor support 86 which is shown in shadows as a fragment 86. The nut 88 is then secured to the bolt 84 to secure the motor support 86 towards the structure 50 reinforced. The bulkhead 68 is a relatively light weight structure for the amount of strength added to the body rail. The walls 70 and 72 can be formed from thin steel embossments, for example from 0.51 to approximately 2.03 millimeters thick. The mild to medium resistance steel is particularly preferred. Also, the sleeve 81 which is preferably a metallic bushing can be a thin walled tube having a wall thickness of about 2.03 to about 5.1 millimeters and preferably of mild steel. Of course, these dimensions are merely illustrative and are not intended to limit the full scope of the invention as defined in the claims. Each fastening flange 80, 82 is generally from about 15 percent to about 30 percent of the length of the walls 70, 72.

The outer diameter of the sleeve 81 will typically be from about 12.7 to about 25.4 millimeters. The width of the polymer layer 74 will be a function of the distance between the walls or plates 70 and 72 and will generally be between about 2.54 to about 10.16 millimeters. It should be understood that the full depth of the screen 68 is filled with the polymer layer 74; that is, as shown in Figure 5 of the drawings, the polymer layer 74 extends from the front of the screen 68 of the back. The polymer used to form the polymer layer 74 is a resin-based material that is thermally expandable. A number of resin-based compositions can be used to form the thermally expanded layer 74 of the present invention. Preferred compositions impart excellent strength and hardness characteristics while adding only marginally to the weight. With specific reference now to the composition of the layer 74, the density of the material should preferably be from about 320.38 grams per liter to about 800.94 grams per liter to minimize the weight. The melting point, the temperature of thermal distortion and the temperature at which the chemical break occurs must also be sufficiently high so that the layer 74 maintains its structure at elevated temperatures typically found in paint ovens and the like. Therefore, layer 74 must be able to withstand temperatures in excess of 160 degrees Centigrade, and preferably 177 degrees Centigrade during short times. Also, layer 74 should be capable of withstanding heats of about 32 degrees C. to 93 degrees C for extended periods without exhibiting substantial distortion or heat induced degradation. The foam 74 may be initially applied to one or both of the walls 70, 72 and then expanded to intimate contact with both walls and with the sleeve 81. Advantageously, the heat of the paint furnace may be used to expand the foam 74 when it is thermally expansible. In more detail, in a particularly preferred embodiment, the thermally expanded structural foam for layer 74 includes a synthetic resin, a cell-forming agent, and a filler. A synthetic resin comprises from about 40 percent to about 80 percent by weight, preferably from about 45 percent to about 75 percent by weight, and most preferably from about 50 percent to about 70 percent by weight of layer 74. More preferably, a portion of the resin includes a flexible epoxy. As used herein, the term "cell-forming agent" generally refers to agents that produce bubbles, pores, or cavities in layer 74. That is, layer 74 has a cellular structure, which has numerous cells disposed to through its mass. This cellular structure provides a material of low density, high strength, which provides a strong structure, however of light weight. Cell forming agents that are compatible with the present invention include "hollow" reinforcing microspheres or microbubbles that can be formed from either glass or plastic. Also, the cell forming agent can comprise a blowing agent which can be either a chemical blowing agent or a physical blowing agent. Glass microspheres are particularly preferred. When the cell-forming agent comprises microspheres or macrospheres, it constitutes from about 10 percent to about 50 percent by weight, preferably from about 15 percent to about 45 percent by weight, and most preferably from 20 percent by weight. one hundred to about 40 weight percent of the material forming the layer 74. When the cell forming agent comprises a blowing agent, it constitutes from about 0.5 percent to about 5.0 percent by weight, preferably from about 1 percent to about 4 percent by weight, and more preferably from about 1 percent to about 2 percent by weight of layer 74 of thermally expanded structural foam. Suitable fillers include glass or plastic microspheres, fumed silica, calcium carbonate, ground glass fiber, and cut glass strand. A thixotropic filler is particularly preferred. Other materials may be appropriate. A filler comprises from about 1 percent to about 15 percent by weight, preferably from about 2 percent to about 10 percent by weight and more preferably from about 3 percent to about 8 percent by weight of layer 74. Preferred synthetic resins for use in the present invention include thermosetting resins such as epoxy resins. It is not intended that the scope of the present invention be limited by the molecular weight of the resin and the appropriate weights will be understood by those skilled in the art based on the present disclosure. When the - le ¬ Resin component of the liquid filling material is a thermosetting resin, various accelerators, such as imidazoles and curing agent, preferably dicyandiamide can also be included to improve the curing regime. A functional amount of accelerator is typically from about 0.5 percent to about 2.0 percent of the weight of the resin with corresponding reduction in one of the three components, resin, cell-forming agent or filler. Similarly, the amount of curing agent used is typically from about I percent to about 8 percent of the weight of the resin with a corresponding reduction in one of the three components, resin, cell-forming agent or filler. The effective amounts of processing aids, stabilizers, colorants, UV absorbers and the like can also be included in the layer. Thermoplastics may also be appropriate. In the following table, a preferred formulation for layer 74 is exposed. E has found that this formulation provides a material that is fully expanded and cured at about 160 degrees C and provides excellent structural properties. All percentages in the present disclosure are percent by weight, unless specifically designated otherwise.

INGREDIENT PERCENTAGE IN WEIGHT EPON 828 (epoxy resin) 37.0 DER 331 (flexible epoxy resin) 18.0 DI-CY (dicyandiamide curing agent) 4.0 IMIDIZOL (accelerator) 0.8 SMOKED SILICA (thixotropic filler) 1.1 CELOGEN AZI99 (asodicarbonamide blowing agent) 1.2 83 MICROS (glass microspheres) 37.0 WINNOFIL CALCIUM CARBONATE (CaCQ3 filler) 0.9 Although the invention has been described mainly in relation to vehicle parts, it should be understood that the invention can be practiced as part of other products, such as airplanes, ships, bicycles or virtually anything that requires energy for movement. Similarly, the invention can be used with stationary or static structures, such as buildings, to provide a rigid support when subjected to vibration such as an earthquake or simply to provide a light weight support for structures subjected to loads. Additionally, even though the invention has been described primarily with respect to thermally expandable foams and with respect to metal parts such as internal tubes 16, 58 and 76, other materials may be used. For example, the foam could be any suitable known expandable foam that is chemically activated into expansion and forms a rigid structural foam. The partition walls 70, 70 and the sleeve 81 could be made of materials other than metal such as various plastics or polymeric materials or various fibrous materials of wood type having sufficient rigidity to function as a back drop or support for the foam. When a thermal expandable foam is used, the walls of the screen and sleeve must be able to withstand the heat encountered during thermal curing. When other types of foam materials are used, however, it is not necessary for the bulkhead and sleeve walls to be able to withstand the elevated temperatures. Instead, the basic requirement for screen and sleeve walls is that they have enough rigidity to function in their intended form. It is also possible, for example, to use as the screen walls and sleeve materials that in themselves become rigid during curing or additional treatment. The invention can also be practiced when the bulkhead and sleeve walls are made of materials other than metal. It is preferred, however, that the materials be selected so that the thin unexpanded foam during the expansion forms a strong bond with the partition walls and sleeve so as to result in a structural composition. Even when particular embodiments of this invention are shown and described herein, it will be understood, of course, that the invention should not be limited thereto, since many modifications can be made, particularly by those experienced in this technique, in the light of this exhibition. It is contemplated, therefore, by the appended claims, to cover any of these modifications that fall within the true spirit and scope of this invention.

Claims (24)

1. - A reinforced structure, comprising a structural member defining a space; a reinforcing member disposed in the space, the reinforcing member having first and second opposed walls; an expanded polymer layer disposed between and bonded to the first and second opposed walls, the expanded polymer being also bonded to the structural member; a sleeve extending through the expanded polymer, the sleeve being disposed between the first and second opposed walls, the expanded polymer being attached to the sleeve; and the sleeve defining a passage adapted to receive a bolt. 2.-. The reinforced structure described in claim 1, further including a bolt extending through the structural member and extending through the sleeve. 3. The reinforced structure described in claim 1, wherein the reinforced structure is a section of a car rail. 4. The reinforced structure described in claim 3, wherein the automobile rail section is a front rail. 5. The reinforced structure described in claim 4, wherein the rail section is U-shaped with flanges extending outwardly, and a cover plate secured to the flanges. 6. The reinforced structure described in claim 1, wherein the opposite walls are welded to the structural member. 7. The reinforced structure described in claim 1, wherein the sleeve is welded to at least one of the first and second walls. 8. The reinforced structure described in claim 1, wherein the reinforced structural member has a pair of through holes in alignment with the pin receiving passage of the sleeve. 9. The reinforced structure described in claim 1, wherein the expanded polymer layer is epoxy, 10. The reinforced structure described in claim 1, wherein the sleeve is substantially parallel with the first and second opposite walls. 11. The reinforced structure described in claim 1, wherein the polymer layer is formed thermally expanded from, in percent by weight, from about 40% to about 60% resin; from about 10% to about 50% microspheres; from about 0.5% to about 5% blowing agent; from about 1% to about 15% filler; from about 0.5% to about 2.0% accelerator and from about 1% to about 8% curing agent. 1

2. A reinforced structural member, comprising: a rail having opposite side walls and defining a longitudinal channel, the longitudinal channel being along a longitudinal axis; a laminated reinforcing member disposed in the channel perpendicular to the longitudinal channel, the laminated reinforcing member having two opposing retaining walls separated by a layer of expanded polymer; a disputed sleeve between the opposing retaining walls and defining a passage; the expanded polymer layer being bound to the opposite walls of the rail, and the sleeve; and a bolt that extends through the rail and the sleeve. 1

3. The reinforced structural member described in claim 12, wherein the rail is made of steel, and the walls having flanges welded to the steel rail. 1

4. The reinforced structural member described in claim 12, wherein the opposing retaining walls each include an internal convex surface in the position of the sleeve. 1

5. The reinforced structure described in claim 12, wherein the sleeve is welded to at least one of the opposite retaining walls. 1

6. The reinforced structure described in claim 12, wherein the expanded polymer layer is epoxy. 1

7. The reinforced structure described in claim 16, wherein the epoxy is thermally expanded and further contains microspheres that reduce the density of the epoxy. 1

8. The reinforced structural member described in claim 12, wherein the laminated reinforcing member has a flange portion at each end thereof. 1

9. A method for reinforcing a structural member having a longitudinal channel therethrough, comprising the steps of: providing a structural member defining a longitudinal channel; provide a laminated structure having two opposite walls separated by an expandable polymer layer; the laminated structure having a sleeve disposed in the expandable polymer layer, the sleeve defining a passage between the opposite walls; placing the laminated structure in the longitudinal channel so that the sleeve passage is substantially perpendicular to the longitudinal channel; welding the laminated structure to the structural member; and actuating the polymer to expand into intimate contact with the walls and the sleeve. 20. The method described in claim 19, wherein the polymer is thermally expandable, and heating the structural member to a temperature sufficient to thermally expand the thermally expandable polymer layer so that the polymer is bonded to the laminated structure to the member structural 21. The method described in claim 19, wherein the structural member is a car rail. 22. The reinforced structure described in claim 20, wherein the epoxy further includes microspheres that reduce the density of the epoxy. 23. A reinforced structural member formed by the process of claim 19. 24.- A reinforced structure, comprising a structural member defining a space; a reinforcing member disposed in the space, the reinforcing member having first and second opposed walls; a thermally expandable polymer layer disposed between and bonded to the first and second opposed walls. the thermally expandable polymer also being bound to the structural member; wherein the thermally expandable polymer layer includes, in percent by weight, 37% epoxy resin, 18% flexible epoxy resin, 4% ida dicyand curing agent, 0.8% imidazole accelerator, 1.1% fumed silica , 1 > 2% azodicarbonamide blowing agent, 37% glass microspheres, and 0.9% calcium carbonate; a sleeve extending through the thermally expandable polymer, the sleeve being disposed between the first and second opposite walls, the thermally expandable polymer being attached to the sleeve; and the sleeve defining a passage adapted to receive a bolt.