Abstract:
A glass sheet used in the making of an aircraft windshield is shaped using the “cut-to-size” method instead of the “out-after-bend” method. In a preferred aspect of the invention the “cut-to-size” method is practiced using a bending iron having a sheet shaping rail having a stationary shaping rail portion mounted on a support member and an articulating shaping rail portion pivotally mounted on the support member for movement from a non-shaping position to a shaping position.

Description:
RELATED APPLICATION 
       [0001]    This application is a divisional of U.S. patent application Ser. No. 13/714,494 filed Dec. 14, 2012, in the names of John E. DeAngelis, Yu Jiao, Dennis D. Warren and Chao Yu, entitled BENDING DEVICE FOR SHAPING GLASS FOR USE IN AIRCRAFT TRANSPARENCIES. U.S. patent application Ser. No. 13/714,494 in its entirety is incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
       [0002]    This invention relates to a bending device, usually referred to in the glass bending art as a bending iron, for shaping glass for use in aircraft transparencies, and more particularly relates to a bending iron for symmetric/asymmetric shaping of glass sheets cut to size for use in the manufacture of monolithic and/or laminated aircraft transparencies. 
       2. Presently Available Bending Device Technology 
       [0003]    Bending devices, commonly referred to in the bending art as Pending irons, are well known for shaping glass sheets for use in the manufacture of monolithic and laminated transparencies for land, water, air and space vehicles. In general, the processing of glass sheets for use in the manufacture of transparencies for land and water vehicles usually include cutting a glass substrate to provide a glass sheet having a predetermined size; moving a bending iron having the glass sheet through a furnace to heat soften and shape the glass sheet; controllably cooling the shaped glass sheet to anneal or heat strength the shaped glass sheet, and using the shaped glass sheet in the manufacture of a transparency for a land or water vehicle. In general, the processing of glass sheets for use in the manufacture of transparencies for air and space vehicles usually include cutting a glass substrate to provide a glass sheet having a predetermined size; moving a bending iron having the glass sheet through a furnace to heat soften and shape the glass sheet; controllably cooling the shaped glass sheet to anneal the shaped glass sheet; cutting the shaped glass sheet to a second predetermined size; chemically strengthening the shaped glass sheet, and using the shaped glass sheet in the manufacture of a transparency for an air or space vehicle. 
         [0004]    The difference between shaping a glass sheet for use with transparencies for land and water vehicles and shaping a glass sheet for use with transparencies for air and&#39;space vehicles of interest in the present discussion is that the glass sheet for use with transparencies for land and water vehicles is cut to size before bending, whereas a glass sheet for use with transparencies for air and space vehicles is cut to an over size before bending and cut to size after bending. For purposes of clarity in the discussion of the glass window, the process for shaping a glass sheet for use with transparencies for land and water vehicles is also referred to as “cut-to-size”, and the process for shaping a glass sheet for use with transparencies in air and space vehicles is referred to as “cut-after-bend”. 
         [0005]    The cut-to-size process is acceptable for making transparencies for land and water vehicles because the glass sheets are thinner, and the optical quality requirement for land and water vehicles is lower than the optical quality requirement for aircraft transparencies. More particularly, the thickness range for glass for automotive transparencies is in the range of 1.8 to 3 millimeters (“mm”) whereas the thickness range for glass for aircraft transparencies is in the range of 2 to 15 mm. Because the glass sheets used for making transparencies for air and space vehicles are thicker, the bending iron having the glass sheet remains in the furnace for a longer period of time to heat the sheet to its bending temperature, which usually results in marring or marking surface areas of the glass sheet in contact with the bending iron during the long heating periods. The marring or marking of the glass sheet can cause distortions on the surface of the glass sheets, which can make the optical quality of the glass unacceptable. Further, the displacement between the glass surface and the metal surface of the bending iron under the high temperature condition will also cause scratches in the glass surface, which results in unacceptable defects. 
         [0006]    As can now be appreciated, the marring and marking of the glass in the vision area is presently reduced or eliminated by providing a bending iron and oversized glass sheet. After glass sheet is shaped, the shaped glass sheet is cut to size. The portions of the glass sheet cut away have the marring and markings from the bending iron. 
         [0007]    As can now be appreciated it would be advantages to provide a bending iron to shape glass sheets for air and space vehicles that does not have the limitations of the presently available bending irons, e.g. but not limited to, a bending iron that does not cause surface defects, which causes optical distortions in the vision area of the transparency; a bending iron that can be used to make symmetric and asymmetric shaped glass sheets without having contact area distortions and scratches in the vision area of the transparency, and a bending iron that can be used in a cut-to-size process for shaping glass sheets to make transparencies for air and space vehicles. 
       SUMMARY OF THE INVENTION 
       [0008]    This invention relates an improved method of shaping a glass sheet to provide a shaped glass sheet for use in the manufacture of an aircraft windshield. The method that is improved by the invention includes, among other steps, the steps of: 
         [0009]    (1) determining the peripheral dimensions of a flat glass sheet defined as desired peripheral dimensions such that when the flat glass sheet having the desired peripheral dimensions is shaped, the shaped glass sheet for use in the manufacture of an aircraft windshield is provided; 
         [0010]    (2) providing a flat glass sheet having peripheral dimensions defined as enlarged peripheral dimensions greater than the desired peripheral dimensions; 
         [0011]    (3) positioning the flat glass sheet having the enlarged peripheral dimensions on shaping rails of a bending device such that the shaping rail of the bending device engages the sheet having the enlarged peripheral dimensions in an area of the sheet between the desired peripheral dimensions and the enlarged peripheral dimensions; 
         [0012]    (4) heating, shaping and cooling the sheet having the enlarged peripheral dimensions; 
         [0013]    (5) cutting the shaped glass sheet having the enlarged peripheral dimensions to provide the shaped glass sheet for use in the manufacture of an aircraft windshield, 
         [0014]    (6) using the shaped sheet from step (5) in the manufacture of the aircraft windshield, wherein the method including steps (1) through (6) is defined as a cut-after-bend method. The improvement includes, among other steps, the steps of: 
         [0015]    (a) practicing step (1); 
         [0016]    (b) providing a flat glass sheet having the desired peripheral dimensions; 
         [0017]    (c) positioning the flat glass sheet having the desired peripheral dimensions on shaping rails of a bending device such that the shaping rail of the bending device engages the sheet having the desired peripheral dimensions in an area of the sheet within the desired peripheral dimensions; 
         [0018]    (d) heating, shaping and cooling the sheet having the desired peripheral dimensions; 
         [0019]    (e) using the shaped sheet from step (d) in the manufacture of an aircraft windshield, wherein the method including steps (a) through (e) is defined as cut-to-size method. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]      FIG. 1  is a cross sectional view of a laminated aircraft transparency illustrating the laminated structure of an aircraft transparency. 
           [0021]      FIG. 2  is an isometric view of a shaped glass sheet having portions removed for purposes of clarity; the shaped glass sheet shaped in accordance to the teachings of the invention. The shaped glass sheet can be used in the fabrication of a laminated aircraft transparency of the type shown in  FIG. 1 . 
           [0022]      FIG. 3  is an isometric view of a non-limiting embodiment of a bending device of the invention that can be used in the practice of the invention to shape glass sheets, e.g. a shaped sheet of the type shown in  FIG. 2 . 
           [0023]      FIG. 4  is an isometric view of an opposite side of the bending device shown in  FIG. 3 . 
           [0024]      FIG. 5  is an isometric view of a flat glass sheet that can be shape in accordance to the teachings of the invention to provide a shaped sheet, e.g. a shaped sheet of the type shown in  FIG. 2 . 
           [0025]      FIG. 6  is a cross sectional view of a non-limiting embodiment of a shaping rail of the invention. 
           [0026]      FIG. 7  is an isometric view of a non-limiting embodiment of a shaping rail that can be used in the practice of the invention. 
           [0027]      FIG. 8  is a perspective view of a non-limiting embodiment of a corner of a shaping rail of the invention. 
           [0028]      FIG. 9  is a side elevated view of a non-limiting embodiment of a sheet retention and alignment member of the invention. 
           [0029]      FIGS. 10 and 11  are enlarged isometric views of a pivot position of an end portion of a non-limiting embodiment of an articulating shaping rail portion of the bending device of the invention shown in  FIGS. 3 and 4 . 
           [0030]      FIG. 12  is an isometric view of a non-limiting embodiment of a biasing arrangement of the invention to move the articulating shaping rail portion of the invention to shape a glass sheet. 
           [0031]      FIG. 13  is an elevated plan view of a flat sheet that can be shape in accordance to the teachings of the invention. 
           [0032]      FIG. 14  is an elevated plan view of a shaped sheet that is shaped in accordance to the teachings of the invention. 
           [0033]      FIG. 15  is an isometric view of a non-limiting embodiment of bending device of the invention that can be used in the practice of the invention to, among other things, shape glass sheets of the type shown in  FIG. 14 . 
           [0034]      FIG. 16  is an enlarged isometric view of a non-limiting embodiment of a biasing arrangement of the invention that is used in the practice of the invention to apply a biasing force to the articulating rail portion of the bending device shown in  FIG. 15 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0035]    As used herein, spatial or directional terms, such as “left”, “right”, “inner”, “outer”, “above”, “below”, and the like, relate to the invention as it is shown in the drawing figures. However, it is to be understood that the invention can assume various alternative orientations and, accordingly, such terms are not to be considered as limiting. Further, as used herein, all numbers expressing dimensions, physical characteristics, processing parameters, quantities of ingredients, reaction conditions, and the like, used in the specification and claims are to be understood as being modified in all instances by the term “about”. Accordingly, unless indicated to the contrary, the numerical values set forth in the following specification and claims can vary depending upon the desired properties sought to be obtained by the present invention. At the very least, and not as an attempt to knit the application of the doctrine of equivalents to the scope of the claims, each numerical value should at least be construed hi light of the number of reported significant digits and by applying ordinary rounding techniques. Moreover, all ranges disclosed herein are to be understood to encompass the beginning and ending range values and any and all subranges subsumed therein. For example, a stated range of “1 to 10” should be considered to include any and ail subranges between (and inclusive of) the minimum value of 1 and the maximum value of 10; that is, all subranges beginning with a minimum value of 1 or more and ending with a maximum value of 10 or less, e.g., 1 to 3.3; 4.7 to 7.5; 5.5 to 10, and the like. 
         [0036]    Before discussing non-limiting embodiments of the invention, it is understood that the invention is not limited in its application to the details of the particular non-limiting embodiments shown and discussed herein since the invention is capable of other embodiments. Further, the terminology used herein to discuss the invention is for the purpose of description and is not of limitation, Still further, unless indicated otherwise in the following discussion, like numbers refer to like elements. 
         [0037]    For purposes of the following discussion, the invention will be discussed with reference to shaping a sheet for an aircraft transparency. As will be appreciated, the invention is not limited to the material of the sheet, e.g. the sheet can be, but is not limited to, a glass sheet or a plastic sheet, in the broad practice of the invention, the sheet can include any desired material having any desired characteristics. For example, the sheet can be opaque, transparent or translucent to visible light. By “opaque” is meant having visible light transmission of 0%. By “transparent” is meant having visible light transmission in the range of greater than 0% to 100%. By “translucent” is meant allowing electromagnetic energy (e.g. visible light) to pass through but diffusing this energy such that objects on the side opposite the viewer are not clearly visible. In the preferred practice of the invention, the sheet is a transparent glass sheet. The glass sheet can include conventional soda-lime-silicate glass, borosilicate glass, or lithium glass used in chemical tempering. The glass can be dear glass. By “dear glass” is meant non-tinted or non-colored glass. Alternatively, the glass can be tinted or otherwise colored glass. The glass can be annealed, heat-treated or chemically tempered. In the practice of the invention, the glass can be conventional float glass, and can be of any composition having any optical properties, e.g., any value of visible transmission, ultraviolet transmission, infrared transmission, and/or total solar energy transmission. By “float glass” is meant glass formed by a conventional float process. Examples of float glass processes are disclosed in U.S. Pat. Nos. 4,744,809 and 6,004,942. 
         [0038]    In the preferred practice of the invention, the glass is a clear transparent glass of the type that can be chemically strengthened. Chemical strengthening or chemical tempering of glass involves an exchange of ions near the surface of the glass. e.g. a glass article with ions from an external source, typically a molten inorganic salt bath, to generate a zone near the surface of the glass which is in a state of compression relative to the interior portions of the glass. A detailed discussion of chemical tempering is present in U.S. Pat. No. 7,871,703, which patent is hereby incorporated by reference, and no further discuss regarding chemical tempering is deemed necessary. As will be appreciated, the invention is not limited to a clear transparent glass that can be chemically tempered, and clear transparent glasses that can be thermally tempered, e.g. soda-lime-silicate glasses of the types disclosed in U.S. Pat. Nos. 8,268,741, and 8,304,358 can be used in the practice of the invention and are hereby incorporated by reference. 
         [0039]    In the preferred practice of the invention, the glass sheet is used in the manufacture of monolithic or laminated transparencies for an aircraft. However as can be appreciated, the shaped glass sheet can be used in the manufacture of any type of transparency, such as but not limited to windshields, windows, rear lights, sunroofs and moonroofs; laminated or non-laminated residential and/or commercial windows; insulating glass units, and/or transparencies for land, air, space, above water and under water vehicles. Non-limiting examples of vehicle transparencies, residential and commercial transparencies, and aircraft transparencies and methods of making the same are found in U.S. Pat. Nos. 4,820,902; 5,028,759, 5,653,903; 6,301,858; and 7,335,421, which patents are hereby incorporated by reference. 
         [0040]    Shown in  FIG. 1  is a non-limiting embodiment of an aircraft windshield  20  that has components that can be made by the practice of the invention. The windshield  20  includes a first glass sheet  22  secured to a second glass sheet  24  by a first interlayer or sheet  26 ; the second sheet  24  secured to a vinyl-interlayer or sheet  28  by a first urethane interlayer  30 , and the second vinyl-interlayer  28  secured to a heatable member  32  by a second urethane interlayer  34 . An edge member or moisture barrier  36  of the type used in the art, e.g. but not limited to a silicone rubber or other flexible durable moisture resistant material is secured to (1) peripheral edge  38  of the windshield  20 , i.e. the peripheral edge  38  of the first and second sheets  22 ,  24 ; of the first and second vinyl-interlayers  26 ,  28 ; of the first and second urethane interlayers  30 ,  34  and of the heatable member  32 ; (2) margins or marginal edges  40  of outer surface  42  of the windshield  20 , i.e. the margins  40  of the outer surface  42  of the first glass sheet  22  of the windshield  20 , and (3) margins or marginal edges  44  of outer surface  46  of the windshield  20 , i.e. margins of the outer surface  46  of the heatable member  32 . 
         [0041]    As is appreciated by those skilled in the art and not limiting to the invention, the first and second glass sheets  22 ,  24 ; the first and second vinyl-interlayers  26 ,  28  and the first urethane interlayer  30  form the structural part, or inner segment, of the windshield  20  and the outer surface  42  of the windshield  20  faces the interior of the vehicle, e.g. an aircraft (not shown), and the second urethane layer  34  and the heatable member  32  form the non-structural part, or outer segment, of the windshield  20 , and the surface  46  of the windshield  20  faces the exterior of the aircraft. As is appreciated by those skilled in the art, the heatable member  32  provides heat to remove fog from, and/or to melt ice on, the outer surface  46  of the windshield  20 . 
         [0042]    As can be appreciated the invention is not limited to the construction of the windshield  20  and any of the constructions of aircraft transparencies used in the art can be used in the practice of the invention. For example and not limited to the invention, the windshield  20  can include a construction wherein the vinyl interlayer  28  and the urethane interlayer  30  are omitted, and/or the sheets  22  and  24  are plastic sheets. Further, the cross section of the window  20  shown in  FIG. 1  shows flat or non-shaped sheets, the invention is not limited thereto and the window  20  can have a contour to match the contour of the outer surface of the aircraft in which the window is mounted. 
         [0043]    Generally the glass sheets  22 ,  24  of the windshield  20  are clear chemically strengthened glass sheets; however, the invention is not limited thereto, and the glass sheets can be heat strengthened or heat tempered glass sheets. Further as is appreciated, the invention is not limited to the number of glass sheets, vinyl interlayers or urethane interlayers that make up the windshield  20 , and the windshield  20  can have any number of sheets and/or interlayers. 
         [0044]    With reference to  FIG. 2  there is shown a shaped glass sheet  120  shaped with a non-limited embodiment of a bending device or bending iron  122  (see  FIGS. 3 and 4 ) of the invention in accordance to the teachings of the invention. With reference to  FIGS. 3 and 4  as needed, the bending device or bending iron  122  includes a ridged main support member  124  to support a shaping rail  126  having a stationary shaping rail portion or stationary rail portion  128  and an articulating shaping rail portion or articulating rail portion  130 . The shaping rail  126  is discussed in detail below. The main support member  124  includes a frame  132  preferably made of a ridged material, e.g. but not limited to 1 inch square hollow steel tubing having a wall thickness of ⅛ inch. The tubing forms an outer boundary of the frame  132 . A cross beam  136  made of the hollow steel tubing has one end  138  joined to an inside surface  140  of a side  142  of the frame  132  (see  FIG. 4 ). Opposite end  144  of the cross beam  136  is joined to the inner surface  140  of opposite side  146  of the frame  132 . The surface  140  faces the interior of the frame  132 . The tubing of the frame  132  and cross beam  136  of the support member  124  are joined together in any convenient manner, e.g. by screws, adhesive or welding, to provide the frame  132  with a predetermined configuration and size compatible with the configuration of the shaping rail  126  as discussed below. In the preferred practice of the invention, the tubing of the frame  132  and cross beam  136  of the support member  124  are welded together in any usual manner. 
         [0045]    The discussion is now directed to the features of the shaping rail  126  of the invention to shape a flat glass sheet  148  (see  FIG. 5 ) to the shaped glass sheet  120  (see  FIG. 2 ). As will be appreciated, the invention is not limited to the embodiment of the shaping rail  126  of the invention shown in  FIGS. 3 and 4  to provide the shaped sheet  120  shown in  FIG. 2 , and the non-limited embodiment of the shaping rail  126  shown in  FIGS. 3 and 4  can be modified within the teachings of the invention to shape the flat sheet  148  (see  FIG. 5 ) to a shaped sheet having a different contour from the contour of the shaped sheet  120  shown in  FIG. 2 . 
         [0046]    With reference to  FIG. 2 , in one non-limiting embodiment of the invention, the shaped glass sheet  120  is used as one sheet of two sheets of a laminated aircraft windshield. In general, the shaped sheet  120  has a first end  150 , an opposite second end  152 , a first side  154  and an opposite second side  156  with the ends  150  and  152 , and the sides  154  and  156  of the sheet  120  defining the perimeter of the shaped sheet  120  and the flat sheet  148  (see  FIG. 5 ). The sheet  120  has a first portion  158  extending from the end  150  to an imaginary line identified by the number  160 , and a second portion  162  extending from the imaginary line  160  to the second end  152  of the sheet  120 . The first portion  158  of the sheet, e.g. the sheet  148  shown in  FIG. 5  is shaped on the stationary portion  128  of the shaping rail  126  and the second shaped portion  162  of the sheet  120  is shaped on the articulating rail portion  130  of the shaping rail  126  (see  FIGS. 3 and 4 ). 
         [0047]    With reference to  FIGS. 3, 4 and 6  as needed, in one non-limiting embodiment of the invention, the stationary portion  128  of the shaping rail  126  on which the sheet  120  or  148  rests is a stainless steel bar  166  having a thickness of ⅛ inch as measured between sides  168  and  169  of the bar  166 , and a length or height as measured between the ends  171  and  172  of 2 inches. The end  171  of the steel bar  166  supporting the glass sheet  120  or  148  is cover with a metal weaved cloth  174  secured to the sides  168  and  169  of the bar  166  in any convenient matter, e.g. by tack welding. In one non-limiting embodiment of the invention, the metal weaved cloth  174  is a stainless steel weaved cloth of the type sold by Bekeart number NP400. 
         [0048]    The stationary rail portion  128  of the shaping rail  126  is maintained in a fixed relationship to the main support member  124  by a plurality of rigid support member  178  of the type used in the art, e.g. of the type disclosed in U.S. Pat. No. 6,629,436, which patent is hereby incorporated by reference. In general and not limiting to the invention, the support members  178  have an end  180  secured to the support member  124 , and an opposite end  182  secured, in any convenient manner to the stationary rail portion  128  of the shaping rail  126 . In the preferred practice of the invention, the end  180  of the support members  178  is welded to the inner surface  140  of the support member  124 , and the opposite end  182  of the support members  178  have a flattened end  183  with a hole (not shown). The hole of the post is aligned with a hole (not shown) in the stationary rail portion  128  of the shaping rail  126  to receive a nut and bolt assembly  184  to secure the stationary rail portion  128  of shaping rail  126  to the end  182  of the support members  178  to maintain the stationary rail portion  128  of the shaping rail  126  in a fixed space relationship to the main support member  124 . 
         [0049]    With reference to  FIGS. 3 and 4 , selected ones of the support members  178  securing the stationary rail portion  128  of the shaping rail  126  to the support member  124  have a re-enforcement rod  188  to provide stability to the stationary rail portion of the shaping rail  126  during the heating and shaping of the glass sheet  120  or  148  supported on the shaping rail  126  of the support member  124 . The invention is not limited to the number of re-enforcement rods  188  used, and the number depends on, among other things, the expected temperature of the furnace, the time the bending iron is in the furnace, the thickness of the support members  178  and the heat absorption of the support members. In one non-limiting embodiment of the invention, the bending iron was used to shape a lithium containing glass for an aircraft windshield. As is appreciated by those skilled in the art lithium containing glass has a shaping temperature of 1040° F., and soda-lime-silicate glass has a shaping temperature of 1090° F. 
         [0050]    The support members  178  were made of stainless steel had a diameter of ⅜ inch and a height of 9 inches. As can now be appreciated by those skilled in the art, the lengths of the supports are dictated by the final shape of the glass and vary depending on the curvature of the final product, The bending iron  122  had stainless steel re-enforcement rods  188  having a diameter of ⅜ inch and a height to provide support for the support members  178 . The side  142  of the main support member  124  had 5 rigid support members  178 ; side  190  between the sides  142  and  146  of the main support member  124  had four rigid supports  178 ; and side  192  (shown as front side in  FIG. 4 ) opposite to the side  190  had six rigid support members  188 . The side  146  of the main support member  124  is discussed with the discussion regarding the articulating rail portion  130  of the shaping rail  126 . The rigid supports  180  of the side  190  had no re-enforcement rods  188  (see  FIG. 3 ). The first and third rigid support members  178  counting from the corner of the sides  142  and  190  of the main support member  124  each had a re-enforcement rod. The side  192  of the main support member  124  had six rigid support members. The two outer and the two center support members  178  had a re-enforcement rod  188 . 
         [0051]    As is appreciated, the invention is not limited to the manner in which the re-enforcement rods  188  are secured to their respective rigid support member  178 . In the non-limiting embodiment of the invention under discussion, end  194  of the rigid support members  188  were welded to the main support member  124  and opposite end  196  was welded to its respective support member  178 . 
         [0052]    With reference to  FIGS. 3, 4, 7 and 8  as needed, in a non-limiting embodiment of the invention, the stationary portion  128  of the shaping rail  126  was made by cutting a flat strip  200  having contours  202  to provide the stationary portion  128  of the shaping rail  128 , and notches  204  at corners, or expected corners  206  (see  FIG. 8 ), of the stationary portion  128  of the shaping rail  126 , and notches  207  at each end  208  of the stationary portion of the shaping rail. The strip  200  is bent to the shape of the stationary rail portion  128  of the shaping rail  126  in any convenient manner. With reference to  FIG. 8 , a post  209  is welded to the surface  169  of the bar  166 , and a tungsten carbide block  210  is secured in position by the post  209 . The notches  204  eliminate the metal bunching at the corners  206  when the strip  200  is bent. The tungsten carbide blocks  210  are secured in the notches at the ends  208  of the bar  166  in any convenient manner. The tungsten carbide blocks  210  at the corners and the ends  208  provide a non-friction surface to support the glass sheet  120  or  146  at the corners  206  and the ends of the stationary portion  128  of the shaping rail  126 . The height of the tungsten carbide blocks is preferable equal to or slightly higher than the height of the bar  166  having the metal weave cloth. 
         [0053]    With reference to  FIGS. 3, 4 and 9  as needed, secured on, and spaced from, the bar  166  of the stationary rail portion  128  of the shaping rail  126  are sheet retention and alignment members  214 . In the preferred practice of the invention, the retention members  214  had a stainless steel core  215  and a carbon sheath  217 ; however, as can be appreciated, the retention members  214  can be one piece made of any material capable of withstanding sanding high temperatures, e.g. made of metal and non metallic material, e.g. plastic, tungsten carbide and carbon. The retention and alignment members  214  had a configuration having a cylindrical bottom portion  216  and a cone shaped top portion  218 . The retention members  214  were connected to the bar  166  of the stationary portion  128  of the shaping rail  126  in any convenient manner, e.g. in the practice of the invention an L-shaped threaded member  220  having long leg  222  of the L-shaped member  220  secured to the bar  166  of the stationary portion  128  of the shaping rail  126  by a pair of bolts  224  threaded on the long leg  222  of the L-shaped member  220  with the stationary portion  128  of the shaping rail  126  between the bolts  224  (see  FIG. 9 ). With continued reference to  FIG. 9 , the cylindrical portion  216  of the retention member  214  extends above the stationary rail portion  128  of the shaping rail  126 . With this arrangement, when the flat glass sheet  148  to be shaped is placed on the shaping rail  126 , peripheral edge  226  of the glass sheet  120  can slide down the surface of the cone shaped portion  218  of the alignment member  214 , and thereafter along the outer surface of the cylindrical portion  216  to align the sheet  148  with the stationary rail portion  128  of the shaping rail  126  and to prevent the sheet  148  from sliding along the shaping rail  126  away from the articulating rail portion  130  of the shaping rail  126  during the sheet shaping process. 
         [0054]    In a non-limiting embodiment of the invention, two retention and alignment members  214  were secured in spaced relationship to one another and 2 inches from the adjacent corner  206  on a segment  228  of the stationary portion  128  of the shaping rail  126  opposite to the articulating rail portion  130  of the shaping rail  126  (see  FIGS. 3 and 4 ), and one retention and alignment member  214  was secured on a segment  230  of the stationary rail portion  128  of the shaping rail  126  adjacent to and spaced 4 inches from the articulating rail portion  130  of the shaping rail  126 , and one of the retention and alignment members  214  was secured to a segment  230  of the stationary rail portion  128  of the shaping rail  126  adjacent to and spaced 4 inches from the articulating rail portion  130  of the shaping rail  126 . The retention members  214  align the sheet  148  on the shaping rail. The alignment and retention members  214  on the segment  228  also limit movement of the sheet  148  away from the articulating rail portion  130  of the shaping rail  126  as the sheet  148  is shaped by the articulating rail portion  130 . The alignment and retention member  214  on the segment  230  of the stationary rail portion  128  of the shaping rail  126  also limits movement of the sheet  148  over the segment  230  of the stationary rail portion  128  of the shaping rail  126  as the articulating rail portion  130  of the shaping rail  126  moves to shape the sheet  148  in a manner discussed below. 
         [0055]    As can now be appreciated, the invention is not limited to the number of alignment members  214  secured on the stationary rail portion  128  of the shaping rail  126  and any number, e.g. 5, 7 or more can be used; further, the invention is not limited to the placement of the retention and alignment members  214  on the shaping rail  126 , and the retention member can be placed at any location of the shaping rail  126  where it can be expected that the sheet  120  can move when the articulating rail portion  130  of the shaping rail  126  moves to shape the sheet  148 . 
         [0056]    The discussion is now directed to the articulating rail portion  130  of the shaping rail  126 . With reference to  FIGS. 3, 4, 10 and 11  as needed, the articulating rail portion  130  includes a shaping rail section  240  mounted on a support frame or cradle  242  by the rigid support member  178  in a similar manner as the bar  166  of the stationary portion  128  of the shaping rail  126  is mounted on the main support member  124  of the bending iron  122 . The support frame  242  is pivotally mounted as discussed below to upright members  244  and  245  of a U shaped frame  246  securely mounted on the main support member  124  and cross beam  136  of the bending iron  122 . The shaping rail section  240  is made of stainless steel bar  248  and shaped to have a generally L-shaped configuration (hereinafter also referred to as “L-shaped bar  248 ”). End  252  of the long leg  250  of the L-shape bar  248  is aligned with the adjacent end  208  of the stationary portion  128  of the shaping rail  126  (see  FIG. 3 ), and end  254  of the short leg  256  of the L-shaped bar  252  is aligned with adjacent end  208  of the stationary portion  128  of the shaping rail  126  (see  FIG. 4 ) such that the shaping rail  126  forms a dosed shaping rail  126 . 
         [0057]    The L-shaped bar  248  in cross section has the same configuration and dimensions as the bar  166  of the stationary portion  128  of the shaping rail  126  (see  FIG. 6 ). The metal weaved cloth  174  covers upper portion of the L-shaped bar  248  and is tack welded to the bar  248  in a similar fashion as the metal weaved cloth  174  is secured on the bar  166  of the stationary portion  128  of the shaping rail  126 . The L-shaped bar  248  is formed in a similar fashion as the bar  166  of the stationary portion  128  of the shaping rail  126  except that there is no notch at junction  260  of the long leg  250  and short leg  257  of the L-shaped bar  248  because the junction  260  has a radius greater than the radius of the bends of the stationary portion  128  of the shaping rail  126 . The larger radius at the junction  260  minimizes, if not eliminates bunching of the L-shaped bar  252  at the junction  248  when the straight bar is bent to the shape of the L-shaped bar  248 . 
         [0058]    As mentioned above, the support frame  242  is pivotally mounted on the upright members  244  and  245  of the U-shaped member  246 . With continued reference to  FIGS. 3 and 4 , the U-shaped frame  246  includes the upright members  244  and  245  interconnected by center member  264 . The center member  264  overlays and is secured to the main support member  124  in any convenient manner, e.g. the central member  264  was connected to the main support member  124  by welding. The center member had a length such that the shaping rail  126  was between the upright members  244  and  245  as shown in  FIGS. 3 and 4 . 
         [0059]    The articulating rail portion  130  of the shaping rail  126  is pivotally mounted to the main support frame  124  in any convenient manner. With reference to  FIG. 3 , the support frame  242  of the articulating portion  130  had a generally L-shaped configuration with a long leg  270  and a short leg  272 . The long leg  270  of the L-shaped support frame  242  was pivotally mounted to the upright member  244  through an arrangement that included an angle iron  274  having leg members  276  and  278 , with the leg member  276  pivotally mounted to the upright member  244  in a manner discussed below, End portion  280  of the long leg  270  of the support frame  242  was curved generally corresponding to the curved end portion of the long leg  250  of the steel bar  248 . The end portion  280  of the long leg  270  of the support frame  242  is welded to the leg member  278  of the angle iron  274 . A gusset plate  284  had end  286  welded to the long leg  270  of the support frame  242  and opposite end  288  of the gusset plate  284  welded to the end portion  280  of the long leg  270  of the support frame  242  as shown in  FIG. 3 . Further, as shown in  FIG. 3 , the upright member  244  included a grooved end  300  to receive the end portion  280  of the leg member  276  of the angle iron  274 . A bolt  302  of a nut and bolt assembly  304  passes through walls  306  of the grooved end  300  of the upright member  244  and through the end portion  280  of the leg member  276  to pivotally mount the angle iron  274  to the upright member  244 . 
         [0060]    The discussion is now directed to pivotally mounting the articulating rail portion  130  of the shaping rail  126  to the upright  245 . With reference to  FIGS. 4, 10 and 11  as needed, the short leg  272  of the support frame  242  of the articulating rail portion  130  of the shaping rail  126  is secured to angle iron  308  in any convenient manner. For example and not limiting to the invention, end portion  310  of the short leg  272  of the support frame  242  of the articulating rail portion  130  was welded to leg member  312  of the angle iron  308  by way of metal rod  313  (see  FIG. 11 ). Other leg member  314  of the angle iron  308  is also welded to the short leg  272  of the support frame  242  of the articulating portion  130  by way of a gusset plate  315  as shown in  FIG. 11 , End portion  316  of the leg member  312  is pivotally mounted to the upright member  245  by the nut and bolt assembly  304  in a similar manner as the leg member  276  of the angle iron  274  is pivotally mounted to the upright member  244  as shown in  FIG. 3 . 
         [0061]    With the leg members  276  and  314  of the angle irons  274  and  308 , respectively, pivotally mounted to their respective upright member  244  and  245  of the U-shaped frame  246 , moving the support member  242  of the articulating rail portion  130  of the shaping rail  126  in a clockwise direction as viewed in  FIG. 3 , or in a counterclockwise direction as viewed in  FIG. 4 , lowers the articulating rail portion  130  of the shaping rail  126  to the sheet receiving position to receive the flat sheet  148  (see  FIG. 5 ). Moving the support member  242  of the articulating rail portion  130  of the shaping rail  126  in the counterclockwise direction as viewed in  FIG. 3 , or in a clockwise direction as viewed in  FIG. 4 , raises the articulating rail portion  130  of the shaping rail  126  to the shaping position to shape the flat glass sheet  148  (see  FIG. 5 ) to the shaped glass sheet  120  shown in  FIG. 2 . 
         [0062]    The invention is not limited to the biasing facilities used in the practice of the invention to move the articulating rail portion  130  of the shaping rail  126  from the non-shaping position to the shaping position. With reference to  FIGS. 3, 4 .  10  and  11  as need, there is shown a biasing arrangement  320  that has been used in the practice of the invention to move the articulating portion  130  from the non-shaping position to the shaping position. It is to be noted that portions of the biasing facilities are missing from  FIG. 4  for purposes of clarity. 
         [0063]    The biasing arrangement  320  ( FIG. 3 ) includes an elongated rod  322  pivotally mounted at a position  324  between ends  326  and  328  of the rod  322  in any convenient manner to an upright  330 . In one embodiment of the invention, end  332  of the upright  330  is welded to a plate  334 , which is welded to the frame  132  of the bending device  122  Opposite end  336  of the upright  330  has a groove  338  to receive the rod  322 . Walls  340  of the groove  338  and the rod  322  at the position  324  have holes  342  to receive nut and bolt arrangement  344 , which includes a bolt  346  in the holes  342  of the walls  340  of the groove  338  and the hole in the position  324  of the rod  322  and secured in position by nuts  348 . With this arrangement, the rod  322  is pivotally mount to the upright  330  at position  324  such that moving the end  326  of the rod  322  in a first direction, e.g. in the direction of arrow  350  moves the opposite end  328  of the rod  322  in a second opposite direction, e.g. in the direction of the arrow  352  (see  FIG. 3 ), or such that moving the end  326  of the rod  322  in a third direction, e.g. in the direction of arrow  354  moves the opposite end  328  of the rod  322  in a fourth opposite direction, e.g. in the direction of the arrow  356  (see  FIG. 3 ). 
         [0064]    A force biasing member or weight  360  is mounted adjacent one of the ends of the elongated rod  322 , e.g. the end  326  (see  FIG. 3 ) to continuously bias the end  326  of the rod  322  in the direction of the arrow  350  to place the articulating rail portion  130  in the shaping position, and to move the opposite end, e.g. the end  328  of the rod  332  in the direction of the arrow  352 . The invention is not limited to the mounting of the force biasing member  360  on any particular end of the rod  322 . In one non-limiting embodiment of the invention, if the articulating rail portion  130  of the shaping rail  126  is heavier at one end, the force biasing member  360  is mounted on the end of the rod adjacent the lighter end of the articulating rail portion  130  to reduce the weight or force that has to be applied to the articulating rail portion  130  to raise the articulating rail portion  130 . More particularly, and with reference to  FIG. 3 , the articulating rail portion  130  of the shaping rail  126  has an L-shape support  240 . In this instance, the force biasing member  360  is preferably mounted on the end  326  of the rod  322 , and the end  328  of the rod  322  is arranged to engage the articulating rail portion  130  at a position adjacent the short leg  242  of the L-shape support  240  of the articulating rail portion  130  in a manner discussed below. To raise the articulating rail portion  130  in the direction of the arrow  352  to move the articulating rail portion  130  to the shaping position. 
         [0065]    In the non-limiting embodiment of the invention under discussion, the L-shape support  240  adjacent the junction of the long leg  270  and the short leg  272  designated by the number  362  has a metal bar  364  having end  366  welded to the position  362  of the L-shaped support frame  240 . The end  328  of the elongated rod  332  passes under the bar  364  such that moving the end  326  of the rod  322  in the direction of the arrow  350  moves the articulating rail portion  130  in the direction of the arrow  352  to move the articulating rail portion  130  to the shaping position and moving the end  326  of the rod  322  in the direction of the arrow  354  movies the end  328  in the direction of the arrow  356  to move the articulating portion  130  to the sheet receiving position or non-shaping position. 
         [0066]    The applied force of the force biasing member  360  is selected to apply sufficient biasing force to raise the articulating rail portion  130  of the shaping rail  126  (see  FIGS. 3 and 4 ) with the sheet  148  (see  FIG. 5 ) supported on the shaping rail  126  and heated to its shaping temperature, and the biasing force should be insufficient to raise the articulating rail portion  130  with the sheet  148  is supported on the shaping rail  126 . In one non-limiting embodiment of the invention, a glass, e.g. a soda-lime-silica glass, and a lithium glass having a thickness of 6 millimeters and heated to their bending temperate were shaped using a force biasing member  360  weighing 3 pounds. In another non-limiting embodiment of the invention, a glass, e.g. a soda-lime-silica glass, and a lithium glass, having a thickness of 14 millimeters, heated to their bending temperature were shaped using a force biasing member  360  weighing 5 pounds. 
         [0067]    In the practice of the invention, a flat glass sheet  148  is placed on the shaping rail  126  of the bending iron  122 . Two ends, e.g. the ends  150  and  152  (see  FIG. 5 ) of the sheet  148  are moved against the three sheet retention and alignment members  214  to align the sheet  148  on the shaping rail  126  of the bending iron  122 . The weight of the sheet  148  moves the articulating rail portion  130  of the shaping rail  126  and the end  328  of the rod  322  in the direction of the arrow  356  and moves the end  326  of the rod  322  and the force biasing member  360  in the direction of the arrow  354 . When the sheet  148  is heated to a temperature within its shaping temperature range, the biasing force of the force applying member  360  moves the end  326  of the rod  332  in the direction of the arrow  350  to move the end  328  of the rod  322  in the direction of the arrow  352  to raise the articulating portion  130  of the bending iron  122  (see  FIGS. 3 and 4 ) to shape the sheet  148 . 
         [0068]    As the articulating rail portion  130  moves in the direction of the arrow  352 , the end  150  of the sheet  148  is prevented from moving off of the shaping rail  126  by the sheet retention and alignment members  214  opposite to the articulating rail portion  130  (see  FIGS. 3 and 4 ). Movement of the articulating rail portion  130  also moves the end  154  of the sheet against the sheet retention and alignment member  214 . As can now be appreciate, the sheet retention and alignment members  214  maintain the sheet  148  in position on the shaping rail  126  during the shaping of the sheet  148  (see  FIG. 5 ) to the sheet  120  (see  FIG. 2 ). 
         [0069]    It was noted that during the shaping of the glass sheet  148  that the glass sheet  148  would occasionally stick in the area of the articulating rail portion  130  adjacent the juncture of the long leg  259  and the short leg  256  of the L-shaped shaping rail of the articulating rail portion  130 . It is believed the sticking was due to the sheet slightly bending over the shaping rail of the articulating rail portion  130  as the articulating rail portion  130  was raised to shape the sheet  148 . To prevent the sheet  148  or  120  from being marred by the movement of the articulating rail portion  130 , a member  367  having a non-friction or reduced friction sliding surface  368  is provide at the curved corner of the shaping rail  240  of the articulating rail portion  130  as shown in  FIGS. 3 and 4 . Reducing or eliminating the sticking of the sheet during the raising of the articulating rail portion  130  reduces marring of the sheet surface, which can cause optical distortion of the glass. In one non-limiting embodiment of the invention, the member  367  was made of metal, e.g. but not limited to stainless steel, 
         [0070]    With continued reference to  FIG. 4 , the movement of the articulating rail portion  130  during the shaping of the glass sheet  148  to obtain the desired curvature is limited by a stop plate  370  secured on the main support member  124  in the path of the end  326  of the rod  322 . A cotter pin  372  is mounted on the end  326  of the rod  322  to prevent the force biasing member  360  from sliding off the rod  322 . 
         [0071]    As can now be appreciated, the invention is not limited to the embodiment discussed and variations in the embodiment can be while maintaining the features of the invention. For example and not limiting to the discussion the parts of the main support frame were joined together by welding, however, the invention is not limited thereto and the components of the bending iron can be secured by any type of fasteners, e.g. but not limited to nut and bolt arrangements and screws made of a material, e.g. steel that can withstand the elevated temperatures of the glass shaping process while maintaining the structural stability of the bending iron. Further, the end  328  of the rod  322  is shown in  FIGS. 3, 4 and 10  as having decreasing diameter so that the contact area between the plate metal bar  364  and the end  328  of the rod  322  is minimized to reduce contact friction as the end  328  of the rod  322  moves along the edge of the metal bar  364 , while maintaining the structural stability of end  328  of the rod  322 , e.g. but not limited to being thick enough to prevent bending of the end  328  of the rod  322 . in one non-limiting embodiment of the invention, the rod  322  at the end  326  had a diameter of ¾ inch and at the end  328  had a diameter of ⅜. 
         [0072]    The invention is not limited to the manner in which the end  328  of the rod  322  of the biasing arrangement  320  (see  FIGS. 3 and 4 ) is connected to the articulating rail portion  130  of the shaping rail  126 . More particularly, and with reference to  FIG. 12 , there is shown another non-limiting embodiment of a biasing arrangement designated by the number  400  for moving the articulating portion  130  to the shaping position. The biasing arrangement  400  includes a rod  402  having a uniform diameter from end  404  to end  406  of the rod  402 . The force biasing member  360  is mounted on the rod  402  between the pivot point  324  and the end  404 , and adjacent the end  404  of the rod  402 . The rod  402  at is pivotally mounted at the position  324  to the upright member  330  in a similar manner as the rod  322  was mounted to the upright member  330  (see  FIG. 3 ). The end  406  of the rod  402  is connected to end  408  of extension rod  410  by two universal joints  412  and  414 , and opposite end  416  of the extension rod  410  is welded to the juncture  362  of the long leg  270  and the short leg  272  of the support frame  242  of the articulating rail portion  130  of the shaping rail  126  (see  FIGS. 3 and 4 ). 
         [0073]    The force biasing member  360  can be secured in position on the end of the rod  402  ( FIG. 12 ) or the rod  322  ( FIGS. 3 and 4 ) in any convenient manner, e.g. by a pressure fit, providing a screw  418  to pass through the force biasing member  360  to engage the rod, e.g. the rod  402  as shown in  FIG. 12  and/or providing external threads  420  (only shown in phantom in  FIG. 12 ) on the rod  402 , and internal threads (not shown) in the passageway  422  of the weight  360 . 
         [0074]    The discussion will now be directed to a bending iron having a shaping rail having two articulating portions to provide a shaped glass sheet having an asymmetric shape, e.g. two different shaped curved sections. More particularly and not limiting to the invention, a bending iron to shape a flat glass sheet  500  (see  FIG. 13 ) to a shaped glass sheet  502  (see  FIG. 14 ) having curved end portions  504  and  506 . A non-limiting embodiment of a bending iron that can be used in the practice of the invention to shape the flat sheet  500  to the shaped sheet  502  is shown in  FIG. 15  and designated by the number  508 . The bending iron  508  has a shaping rail  510  having a first stationary shaping rail portion  512  and a second stationary shaping rail  514  to shape center portion  516 , i.e. the portion  516  of the sheet between the curved segments  504  and  506 , a first articulating shaping rail portion  518  to shape the curved segment  504  and a second articulating shaping rail portion  520  to shape the curved segment  506 . The shaped sheet  502  can he used for a monolithic or in a laminated window of an aircraft. 
         [0075]    The bending iron  508  includes a main support member  522  and a shaping rail support member  524 . The shaping rail support member  524  is secured on the main support member  522  by welding. As shown in  FIG. 15 , the shaping rail support member  524  is space at different distances from the main support member  522  to provide a tilt to the shaping rail support member  524  such that gravity aids in keeping the sheets  500  and  502  on the shaping rail  510  during the shaping of the sheet  500 . The invention is not limited to the manner in which the shaping rail support member  524  is spaced and secured to the main support member  522 . In one non limiting embodiment of the invention, corner  526  of the shaping rail support member  524  is secured to the main support member  522  by a vertical shim  528  welded to the shaping rail support member  524  and the main support member  522 ; at corner  530  of the shaping rail support member  524 , the shaping rail support member  524  is secured to the main support member  522  by welding a section of steel tubing  532  and plates  584  to the shaping rail support member  524  and the main support member  522  as shown in  FIG. 15 ; the corner  536  of the shaping rail support member  524  is secure to the main support member  522  by welding a section of steel tubing  538  to the shaping rail support member  524  and the main support member  522  as shown in  FIG. 15 , and the corner  540  of the shaping rail support member is welded directly to the main support member  522  as shown in  FIG. 15 . 
         [0076]    The first stationary shaping rail portion  512  and the second stationary shaping rail portion  514  are fabricated in a similar manner as the stationary shaping portion  128  of the shaping rail  126  (see  FIGS. 3 and 4 ) except that no bending was required for corners (see  FIG. 8 ). The first stationary shaping rail portion  512  and the second stationary shaping rail portion  514  are secured to the shaping rail support member  524  by the ridged support member  178 , and the nut and bolt assembly  184  in a similar manner as the stationary portion  128  of shaping rail  126  was secured to the frame  132  (see  FIGS. 3 and 4 ). 
         [0077]    With reference to  FIG. 15 , the discussion is now directed to the first articulating shaping rail portion  518 . The first articulating shaping rail portion  518  includes a shaping rail  542  having a generally U-shape and is connected to a stabilizing bar  544  by the ridged support member  178 , and the nut and bolt assembly  184  in a similar manner as the stationary portion  128  of shaping rail  126  was secured to the frame  132  (see  FIGS. 3 and 4 ). Leg  546  of the first articulating shaping rail portion  518  is pivotally mounted at pivot point  548  to end  550  of an upright  552  by a bolt and nut arrangement  554 . Leg  556  of the first articulating shaping rail portion  518  is pivotally mounted at pivot point  558  to end  660  of an upright  562  by a nut and bolt arrangement  564 . End  566  of the upright  552  and end  568  of the upright  562  are each welded to the shaping rail support member  524 . A strengthening bar  570  has one end  572  connected to the pivot point  558  and end portion  574  welded to the stabilizer bar  570 . 
         [0078]    A biasing device  576  discussed in more detail below is connected in a manner discussed below to move the first articulating shaping rail portion  518  in a counterclockwise direction as viewed in  FIG. 15  to move the first articulating shaping rail portion  518  from the non-shaping position to the shaping position. 
         [0079]    With continued reference to  FIG. 15 , the discussion is now directed to the second articulating shaping rail portion  520 . The second articulating shaping rail portion  520  includes a shaping rail  590  having a generally U-shape configuration and is connected to a stabilizing bar  592  by the ridged support members  178 , and the nut and bolt assembly  184  in a similar manner as the stationary portion  128  of shaping rail  126  was secured to the frame  132  (see  FIGS. 3 and 4 ). Leg  594  of the second articulating shaping rail portion  520  is pivotally mounted at pivot point  596  to end  598  of an upright  600  by a bolt and nut arrangement  602 . Leg  604  of the second articulating shaping rail portion  520  is pivotally mounted at pivot point  606  to end  608  of an upright  609  by a bolt and nut arrangement  610 . The pivot arrangement at pivot point  606  for the upright  609  of the second articulating shaping rail portion  520  is similar to the pivot arrangement for the pivot point  548  for the upright  552  of the first articulating shaping rail portion  518  as shown in  FIG. 15 . 
         [0080]    A biasing device  614  discussed in more detail below is connected in a manner discussed below to move the second articulating shaping rail portion  520  hi a clockwise direction as viewed in  FIG. 15  to move the second articulating shaping rail portion  520  from the non-shaping position to the shaping position. 
         [0081]    The biasing device  614  shown in  FIG. 15  includes a force biasing member  620  mounted on a ridged L-shaped rod  622  having a long leg  624  and a short leg  626 . The force biasing member  620  is mounted on the long leg  624  and secured in position by screws  628  passing through a collars  630  mounted on the long leg  624  on each side of the force biasing member  620  and engaging the long leg  624  of the rod  622 . The short leg  626  of the rod  622  is connected at end  632  to a first outer leg  634  of a U-shaped member  636 . A metal gusset plate  638  has one end welded to the short leg  626  and an opposite end welded to the long leg  624  of the L-shaped rod  622 . A metal rod  640  has one end welded to the first outer leg  634  of the LI-shaped member  636  and the opposite end welded to the L-shaped member, e.g. but not limiting to the invention, the juncture of the short leg  626  and the long leg  624  of the L-shaped rod  622 . Second outer leg  642  of the U-shaped member  636  has its end  644  connected to the pivot point  596  and is welded to outer surface of the leg  594  of second articulating shaping rail portion  520 . 
         [0082]    With the above discussed arrangement of the biasing device  614 , the biasing force of the force biasing member  620  moves the second articulating shaping rail portion  520  in a clockwise direction as viewed in  FIG. 15  to move the second articulating shaping portion  520  to the shaping position. The downward motion of the force biasing member  620  is limited by a stop plate  646  mounted on a metal support member  648 . The metal support member  648  has one end welded to the shaping rod support member  524  and the opposite end welded to the main support member  522 . 
         [0083]    With reference to  FIGS. 15 and 16  as needed, the connection of the biasing device  576  to the first articulating shaping rail portion  518  is similar in construction to the connection of the biasing device  614  to the second articulating shaping rail portion  620  presented above except that the stop  646  is mounted on a metal strip  650  connected to the corner  540  of the shaping rail support member  524 . With this arrangement the biasing force of the weight  620  of the biasing device  576  moves the first articulating shaping rail portion  518  in a counterclockwise direction as viewed in  FIG. 15  to move the first articulating shaping portion  518  to the shaping position. The stop plate  646  limits the downward motion of the force biasing member  620  of the biasing device  576 . 
         [0084]    Other variations as are known to those skilled in the art can be resorted to without departing from the scope of the invention as defined by the claims that follow.