Abstract:
A method of reforming a thermoplastic elastomeric composite weatherstrip for a window opening of a motor vehicle comprises the steps of fabricating the weatherstrip through extrusion, molding or other conventional means, heating a section of the weatherstrip to be reformed, applying and conforming the heated section to a curved form or fixture having an included angle greater than the desired final configuration, cooling the weatherstrip while maintaining contact with the fixture and aging the formed weatherstrip to achieve angular equilibrium. The resulting weatherstrip product is also disclosed and claimed.

Description:
TECHNICAL FIELD OF THE INVENTION  
       [0001]     The invention relates to a method of fabricating a motor vehicle weatherstrip and more particularly to a method for reforming a thermoplastic elastomer composite weatherstrip and the resulting weatherstrip.  
       BACKGROUND OF THE INVENTION  
       [0002]     Generally speaking, motor vehicles are equipped with moveable windows that slide in a window frame between a closed position wherein the window closes and seals an opening and an open position wherein the window is retracted within a door or body panel and allows the entry of air into or exhaust of air from the passenger compartment. Weatherstrip is disposed about the periphery of the window opening and provides an airtight and watertight seal between the window glass and the window frame. One type of weatherstrip, referred to as an edge seal, defines a groove that slidably receives a window edge and includes surfaces that form a seal against the window. Another type of weatherstrip, referred to as a beltstrip, is disposed adjacent the window on the exterior of the vehicle where the window retracts into the door or body panel and includes a wiper flange that wipes the surface of the window as it is retracted or raised.  
         [0003]     Weatherstrips perform both an aesthetic function and a mechanical function. Aesthetically, the weatherstrip provides an interface between the window and door or body panel and must therefore present an attractive appearance. Additionally, of course, the weatherstrip must achieve an air and watertight seal between the window glass and door or body panel. It should also be understood that the weatherstrip must provide a desirable, typically smooth, aerodynamic shape as this minimizes wind noise and lowers the coefficient of drag of the vehicle.  
         [0004]     These goals suggest that minimizing the number of weatherstrip components around a given window opening would be desirable. While this is true, achieving a unitary gasket ignores not only the different roles of beltstrips and edge seals but also ignores the complex window shapes and door configurations in which the weatherstrips must function. For example, a right angle corner, between the door header and the vehicle B pillar typically requires two mitered edge seal pieces. The use of two separate pieces complicates installation and may result in gaps between the edge seal ends which may compromise the seal. An obvious alternative involves gluing or heat sealing the mitered ends of the edge seals together. In such an assembly, even if properly adhered to one another, the mitered and adhered ends generally represent a weak spot where failure may eventually occur. If not properly adhered they may be a site of air and water leakage.  
         [0005]     While many window/door panel corners may be curved, fitting a straight and unformed section of edge seal into a curved window opening invariably results in wrinkling and misshapen edge seal components, particularly in the inside of the edge seal which is that region which accepts the window glass. Thus, while eliminating a junction between two ends of edge seal, conforming a straight edge seal to the contour of a curved window opening is also accompanied by installation and service difficulties.  
         [0006]     The present invention relates to a method of reforming a motor vehicle weatherstrip, specifically an edge seal, and addresses and solves the foregoing problems.  
       SUMMARY OF THE INVENTION  
       [0007]     In accordance with this invention, a method of reshaping or reforming a thermoplastic elastomeric composite weatherstrip for a window opening of a motor vehicle comprises the steps of fabricating the weatherstrip through extrusion, molding or other conventional means, heating a section of the weatherstrip to be reformed, applying and conforming the heated section to a curved form or fixture having an included angle greater than the desired final configuration, cooling the weatherstrip while maintaining contact with the fixture and aging the formed weatherstrip to achieve angular equilibrium. The weatherstrip may thus be fabricated to accurately complement one or more curved window and door or body panel corners. The resulting weatherstrip product is also disclosed.  
         [0008]     Thus it is an object of the present invention to provide a method for providing a motor vehicle weatherstrip which accurately fits a curved corner in a window opening of a door or body panel.  
         [0009]     It is a further object of the present invention to provide a method for reforming a thermoplastic elastomer composite weatherstrip.  
         [0010]     It is a still further object of the present invention to provide a method for reshaping or reforming a thermoplastic elastomer weatherstrip into a shape which closely matches a profile of a motor vehicle door or body panel window opening.  
         [0011]     It is a still further object of the present invention to provide a reshaped or reformed motor vehicle weatherstrip which closely matches the curved of a window opening in a door or body panel of a motor vehicle.  
         [0012]     Further objects and advantages of the present invention will become apparent by reference to the following description of the preferred embodiment and appended drawings wherein the like reference numbers refer to the same component, element or feature. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]      FIG. 1  is a fragmentary, side elevational view of a motor vehicle incorporating the present invention;  
         [0014]      FIG. 2  is an enlarged, cross-section of a motor vehicle weatherstrip for use with the present invention taken along line  2 - 2  of  FIG. 1 ;  
         [0015]      FIG. 3  is a diagrammatic view of the fabrication by extrusion of a weatherstrip for the present invention;  
         [0016]      FIG. 4  is a diagrammatic view of the weatherstrip heating step of a method according to the present invention;  
         [0017]      FIG. 5  is a top plan view of a forming fixture for use with the present invention;  
         [0018]      FIG. 6  is a diagrammatic view of the weatherstrip forming step of a method according to the present invention;  
         [0019]      FIG. 7  is a diagrammatic view of the weatherstrip cooling step of a method according to the present invention; and  
         [0020]      FIG. 8  is a diagrammatic view of the weatherstrip aging step of a method according to the present invention.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0021]     Referring now to  FIG. 1 , a typical consumer motor vehicle such as a passenger car, pick-up truck, sport utility vehicle (SUV), or station wagon is illustrated and designated by the reference number  10 . The motor vehicle  10  includes a body  12 . The motor vehicle body  12  typically includes front doors  14 , one of which is illustrated in  FIG. 1 , and rear doors  16 , one of which is also illustrated in  FIG. 1 . Each of the front doors  14  includes an upper frame assembly  24  and a front lower door panel  26  which generally defines a front opening which receives a front window or glass light  28 . About the periphery of the glass receiving opening is a front weatherstrip assembly  30 . Likewise, the rear door  16  includes a rear upper frame assembly  44  and a rear lower door panel  46  which define an opening which receives a rear window or glass light  48 . Once again, the glass receiving opening is trimmed with and receives a rear weatherstrip assembly  50 . Both the front and rear window weatherstrip assemblies  30  and  50  will generally include a belt strip  32  and  52 , respectively, which extends across the lower portion of the window opening and the upper portion of the door panels  26  and  46 , respectively, to form an interface between the front and rear lower door panels  26  and  46  and the respective glass lights  28  and  48 . The weatherstrip assemblies  30  and  50  also include front and rear edge seals  34  and  54  which acts as an interface between the front and rear glass lights  28  and  48  and the respective door frames  24  and  44 .  
         [0022]     Referring now to  FIG. 2 , the front edge seal  34  defines a generally S-shaped body having a first channel  60  which receives a flange  61  of the upper frame assembly  24  thereby retaining and securing the edge seal  34  to the upper door frame assembly  24  of the front door  14 . Assisting such retention is a plurality of projecting, opposed lips or flanges  62  which engage the flange  61  of the door frame assembly  24 . A continuous terminal lip portion  64  engages and seals against the door frame assembly  24  and exhibits sufficient flexibility to accommodate dimensional variations in, for example, the size of the flange  61  to provide an aesthetically attractive seal. A wound, coiled, slotted or perforated metal insert  66  provides strength, shape and rigidity to the weatherstrip  64  and is preferably fully embedded or surrounded by the thermoplastic material of the edge seal  34 .  
         [0023]     The edge seal  34  also includes a second channel  70  which receives the glass light  28 . At the mouth of the second channel  70  are a plurality of obliquely oriented flanges or wipers  72  which engage the glass light  28  and seal there-against. The surfaces of the flanges or wipers  72  and the base of the second channel  70  may include a low friction material  74  such as flocking, a thermoplastic coating or a thin layer of a polymer resin such as Teflon. Teflon is a registered trademark of the E.I. DuPont deNemours Co. for its brand of fluropolymer resin. Other polyolefin based materials such as polyethylene and polypropylene may also be used.  
         [0024]     Referring now to  FIG. 3 , fabrication of the edge seal  34  by an extrusion process is illustrated. An extruding machine  76  having conventional material heating, extruding and cooling stations includes a hopper  78  filled with a suitable thermoplastic material and receives the wound, coiled, slotted or perforated insert  66 . The thermoplastic material is heated, formed about the insert  66  in a suitably shaped extrusion die (not illustrated) and is cooled while passing through a series of forming dies to attain its final form after exiting the extruding machine  76 . Preferably, the edge seal  34  is passed through a series of rollers  80  which straighten the edge seal  34 . The edge seal  34  is preferably fabricated of a thermoplastic elastomer (TPE) or a thermoplastic vulcanizate (TPV). Although the edge seal  34  is preferably fabricated by extrusion, it may also be made by any suitable molding or forming operation.  
         [0025]     It will be appreciated that the edge seal  34  illustrated is exemplary in nature and that the method disclosed and claimed herein may be practiced with weatherstrips and edge seals having various and sundry specific configurations. They will, however, generally define the S-shape disclosed herein which receives, in oppositely directed channels, a mounting flange extending from the vehicle or vehicle door and a moveable glass light.  
         [0026]     Referring now to  FIG. 4 , the edge seal  34 , which has, as noted above, been fabricated by extrusion or other process, is placed in proximity to an infrared heater  84  which heats a length, typically between four and six inches (102 mm to 152 mm) and preferably about 5 inches (127 mm) of the edge seal  34 . The edge seal  34  is heated to a temperature of between 250° and 290° Fahrenheit (121° C. to 143° C.) and preferably between 265° and 270° Fahrenheit (129° C. to 132° C.) for two to four minutes and preferably about three minutes such that the thermoplastic material of the edge seal  34  is well heated and softened but not so high in temperature or heated for so long a time that the thermoplastic material begins to melt. The heat is applied to the base of the edge seal  34  forming the second slot  70  for the glass light  28 . As noted, the heat is preferably provided by an infrared heater  84  such as a quartz lamp electric heater although a forced air (convection) heater or a combination of radiant and convection heating may also be utilized. Although the heating of only a single length of the edge seal  34  has been shown, it will be appreciated that two (or more) regions of the edge seal  34  may be heated simultaneously in order to perform and achieve two (or more) curved regions of the edge seal  34  as may be routinely encountered in a typical window installation, i.e. the curved corners at the front and rear intersections of the upper horizontal window frame with vertical or oblique members.  
         [0027]     As illustrated in  FIGS. 5 and 6 , the edge seal  34  having a heated section of, as noted, between four and six inches and, in any event, a length corresponding to the total involved length of a curved corner such as that illustrated in  FIG. 1  is then tightly disposed about the peripheral forming edge  88  of a curved rail or fixture  90 . The fixture  90  includes a curved peripheral projection  92  having a projecting distance nominally equal to the depth of the slot  70 . Thus, when the edge seal  34  is placed firmly on the fixture  90 , the forming edge  88  of the projection  92  engages the bottom surface of the slot  70  and thereby closely conforms the heated portion of the edge seal  34  to the precise radii of curvature of the fixture  90  and the projection  22  and to the shape desired. Because of springback or hysteresis, the extent of curvature of the fixture  90  (in degrees) will typically and preferably be greater than the desired final curvature. That is, if as is typical, a 90° bend is desired to conform to the change from a horizontal section of the door frame to a vertical section, the edge seal  34  must be initially bent or formed to an angle typically 20° to 40° greater. Because of springback or hysteresis, therefore, to make a 90° bend it is generally necessary to extend the curved portion of the edge seal  34  beyond 90° and typically to 110°, 120°or 130° measured as an obtuse angle (or 70°, 60°, 50° measured as an acute angle), depending upon the springback experienced or displayed by a particular edge seal  34 .  
         [0028]     Referring now to  FIG. 7 , the edge seal  34  is maintained on the forming edge  88  of the rail or fixture  90  and is then subjected to spray  98  from a water spray apparatus  100 . The water spray  98  cools the edge seal  34  to a temperature of approximately 65° to 75° Fahrenheit (19° to 24° Centigrade). Alternatively, the edge seal  34  may be cooled by chilled air or any other means capable of lowering the temperature of the edge seal  34  to approximately room temperature in a relatively short period of time.  
         [0029]     In the forming step, the uncross-linked hydrocarbon chains of the thermoplastic material are stretched and reformed. During the cooling step these chains are fixed in their stretched positions such that the edge seal  34  generally takes on the curved shape of the rail or fixture  90 .  
         [0030]     Finally, and with reference now to  FIG. 8 , the formed and cooled edge seals  34  are placed on a rack  102  to reach angular equilibrium. As stated above, due to springback or hysteresis, the edge seal  34  is over-formed, i.e., formed to an angle in excess of the typical right angle (90°) or other angle such as between the vehicle A pillar and the top of a door desired. During the racking and equilibrium step, the edge seal  34  though initially formed at, for example, 110° or 115° will relax over several hours or longer to an angle very near or consistent with the desired angle such that the shapes and contour of the edge seal  34  conforms closely to both the corner of a window and the vehicle door or body.  
         [0031]     While this invention has been described in terms of certain embodiments thereof, it is not intended to be so limited, but rather should be limited only to the extent set forth in the claims that follow.