US 3868789 A
A window for boats, trailers and the like comprises a pane element which is arcuately curved along at least a portion of its periphery. A frame member for the pane extends effectively continuously circumferentially of the pane and mounts the pane therein. The frame member is fabricated of a rigid synthetic thermoplastic extrusion and, in cross-section, defines a web extending substantially normal to the pane and spaced pane flanges extending from one side of the web and between which the pane is disposed. The frame member extends continuously along the peripheral portion of the pane and is correspondingly arcuately curved along said portion in a direction normal to the web. The window includes means for securing the frame member in a window opening and this means includes a mounting flange extending from the opposite side of the web along the circumference of the window.
Description (OCR text may contain errors)
United States Patent [191 11] 3,868,789 Gates Mar. 4, 1975  WINDOW WITH EXTRUDEI) SYNTHETIC 3,555,736 l/l97l Koch, Jr. et al. 52/2 08 X ggfiwmfigggggflggagg FOREIGN PATENTS OR APPLICATIONS 935,560 8/1963 Great Britain 264/339  Inventor: John 1. Gates, Pasadena, Calif.
 Assignee: Clifford C. Oliver, Newport Beach, Primary Downey C lif a n interest Attorney, Agent, or FirmChristie, Parker & Hale  Filed: Feb. 5, 1973 l 21 A l N 329 851  ABSTRACT 1 pp O" 1 A window for boats, trailers and the like comprises a Related US. Application Data pane element which is arcuately curved along at least  Continuation of Ser, No, 145,366, M 2 1971, a portion of its periphery. A frame member for the abandoned. pane extends effectively continuously circumferentially of the pane and mounts the pane therein. The  [1.8. CI 49/50l, 52/212, 52/627, frame member is fabricated of a rigid synthetic ther- 52/309, 49/504, 264/322, 264/339 moplastic extrusion and, in cross-section, defines a  Int. Cl E06b 3/00 web extending substantially normal to the pane and  Field of Search 49/501, 504; 52/309, 208, spaced pane flanges extending from one side of the 52/644, 212, 624, 627, 658; 264/295, 339 web and between which the pane is disposed. The
frame member extends continuously along the periph-  References Cited eral portion of the pane and is correspondingly arcu- UNITED STATES PATENTS ately curved along said portion in a direction normal 1 386 068 8/1971 Ma mud 264/322 X to the web. The window includes means for securing 5279345 4/1922 Karl.......1::::"':::3::11113:::111 52/658 the frame nnennben in n window opening end the 2:3g3:297 11/1945 52/309 X means includes a mounting flange extending from the 2,902,727 9/1959 Saniolis..... 52/212 Opposite side of the web along the circumference of 3,087,537 4/1963 Levan 160/91 the Window. 3,206,888 9/1965 Litzkal 52/644 X 3,221,456 l2/l965 Cape] 52/208 x 10 Clams, 24 Drawmg Figures PATENTED W 41975 3 868 789 sum 01 0F 10 v INVENTOR. JOHN J. '64755 PATENIEDRAR 4815 3.868.789
sum new 10 sum mar 10 WINDOW WITH EXTRUDED SYNTHETIC FRAME AND METHOD AND APPARATUS FOR MANUFACTURE THEREOF CROSS REFERENCE TO RELATED APPLICATIONS This is a continuation of application Ser. No. 145,866, filed May 21, 1971, now abandoned.
Field of the Invention This invention pertains to windows for use in boats, camper trailers and the like. More particularly, the invention pertains to an improved window in which the window frame is defined by bent extrusions of rigid thermoplastic material. The invention also pertains to a method for bending an element of substantially rigid synthetic thermoplastic material having a web and at least one flange extending therefrom without significant distortion of the cross-sectional configuration of the element. The invention also pertains to apparatus for performing this bending method.
BACKGROUND OF THE INVENTION Until very recently windows for use in sailboats, motorboats, yachts, camper trailers, house trailers and the like were fabricated of glass mounted in metal frames. For large boats, such as luxury yachts, the frames are made of brass, stainless steel or other corrosion resistant metal. These frame materials, however, are quite expensive and their use is not justified in the smaller windows required for sailboats, motorboats and campers trailers, for example. In smaller recreational vehicles, such as boats, camper trailers and the like, it is current practice to fabricate the window frames of bent extruded aluminum shapes. Aluminum, however, is susceptible to corrosion, especially in salt atmospheres such as are encountered in marine applications. Corrosion of aluminum window frames may be prevented by painting the frame, but this maintenance effort is not always pursued; also, paint does not adhere readily to aluminum, with the result that where a diligent painting program is pursuedthe window frames must be repainted frequently.
Recently, in an effort to overcome the disadvantages associated with aluminum frames, a window having a frame fabricated of thermoplastic material has recently been introduced commercially for use in small boats. This product has a pane of transparent synthetic resin and a one-piece frame fabricated of vacuum-formed ABS resin to which the pane is bonded. Because the frame is fabricated by vacuum forming techniques, the thickness of the frame material is necessarily relatively thin. Accordingly, these windows flex readily and the bond between the pane and the frame may break in re sponse to such flexing. These windows have the advantage that they are made entirely of synthetic materials which are resistant to corrosion and which can be colored to harmonized with the remaining structure in which they are installed. These windows, because of their one-piece frame construction, are either bonded or screwed to the basic boat structure peripherally of the window opening. Where provided, an interior trim frame is merely bonded or screwed to the interior of the boat structure for the purposes of ornamentation. The trim frames have no structural cooperation with the support frame for the pane, and are not relied upon to mount the window in the window opening.
Because the pane supporting frames ofthe aforementioned all-synthetic windows are formed by vacuum forming techniques, the cross-sectional configuration of the frame necessarily must be simple. The complex cross-sectional shapes achievable in extrusions cannot be formed by vacuum forming techniques. Accordingly, existing all-synthetic resin windows are not openable in that the transparent pane of these windows is bonded to the supporting frame entirely around the periphery of the pane. An advantage of the more expensive windows having stamped or extruded frames is that such windows can have a fixed pane, a second movable openable pane and, if desired, a screen; these features are not possible where the frame is fabricated by vacuum forming or similar techniques.
It is known that attempts have been made to provide a window for camper trailers, boats and the like wherein the window frame is defined by an extruded rigid synthetic resin. These attempts sought to realize the increased advantages of a window having an extruded frame; these advantages include the ability to provide openable windows with or without screens and the increased structure strength obtainable with an extruded frame, thereby providing a window frame which does not flex and separate from the pane. These prior attempts were not successful, and it is believed that I these failures were caused by the difficulties attendant to bending the normally straight extrusion into the appropriate curvature necessary for these types of windows. Aluminum is readily extrudable into myriad shapes of complex cross-sectional configuration, and these extrusions are bendable from a straight into a curved shape by techniques similar to the techniques used in pipe bending, for example. These techniques are dependent upon the cold-flowability of aluminum under extreme loads. Synthetic resins having the desired characteristics of rigidity and strength, however, do not possess these cold-flowable characteristics, with the result that techniques found successful for the bending of aluminum extrusions cannot be adapted to the bending of extrusions fabricated of synthetic materials such as rigid thermoplastic resins.
It is apparent from the foregoing, therefore, that a need exists for the provision of windows for boats, camper trailers and the like, in which the window frame is fabricated of an extruded synthetic material. Similarly, in order that these products may be produced, a need exists for the development of processes and equipment for the bending of rigid thermoplastic shapes without fracture of the thermoplastic material and without loss of the cross-sectional configuration defined by the shape.
SUMMARY OF THE INVENTION This invention provides a window for habitable recreational vehicles and the like in which the frame is fabricated of extruded rigid thermoplastic material. The frame of this window is not readily flexible in use, and therefore the desired seal between the pane and the window frame is maintained under adverse conditions frame to the surrounding structure. Also, windows ac cording to this invention can be openable and can be provided with or without screens, as desired.
Generally speaking, a window according to this invention includes a translucent pane and a frame member for the pane. The frame member extends circumferentially of the pane and'mounts the pane therein. The frame member is fabricated of rigid synthetic thermoplastic material and defines a web which extends substantially normal to the pane adjacent the edge of the pane; The frame also includes spaced pane flanges which extend from one side of the web and between which the pane is disposed. Means for securing the frame member in an opening in a boat hull and the like include a mounting flange which extends from the opposite side of the web along the circumference of the window. Preferably the window frame member is fabricated from a rigid thermoplastic extrusion.
This invention also provides a method for bending an elongate element fabricated of substantially rigid synthetic thermoplastic material having a web and a flange extending from the web, and it is a feature of this methodthat the element be bent without significant distortion of the cross-sectional configuration of the element. The method includes the step of intimately mating the element at one end of the extent thereof to be bent between first and second dies. The dies are cooperatively configured to define the curvature to which the element is to be bent and to mate with the crosssectional configuration of the element. The method also includes the step of heating the mated element with a heating fluid sufficiently to cause the thermoplastic material from which the element is defined to lose a substantial portion but not all of its tensile strength. The heating of the element is continued along the extent of the element to be bent in conjunction with the step of progressively moving the dies into intimately mating engagement with the element over the entire extent of the element to be bent. Then, after the element has been bent to the desired curve and is still intimately mated between the dies, the element is cooled sufficiently to restore the rigid characteristic to the thermoplastic material.
In terms of apparatus for performing the bending method, this invention provides apparatus which includes a rigid die member defining a die surface configured to intimately mate with a portion of the crosssectional configuration of the element prior to and during bending of the element. The die surface preferably is convexly curved and is arranged to define the desired curve to which the element is to be bent. A flexible die is configured in cooperation with the rigid die to mate intimately with substantially the remainderv of the crosssectional configuration of the element when bent. Means are provided for heating the rigid die member and, via at least the rigid die member, an element mated with the rigid die sufficiently to soften the element to a plastic state. The bending apparatus further includes means for forceably mating and confining an element between the rigid and flexible dies over a length of the convex die surface of the rigid die which defines the desired curve.
It is preferred that the frame member provided in a window of this invention be fabricated of rigid vinyl material. It is also preferred that, during the bending process, the rigid vinyl extrusion be heated by applying saturated steam directly to the extrusion to cause the rigid vinyl to soften sufficiently to permit bending of the extrusion without tearing of the material during the bending process. Saturated steam has the advantage that its temperature corresponds almost exactly to the optimum temperature to which the rigid vinyl must be raised to permit bending to a curve without tearing of the extrusion. Also, the saturated steam can be provided without complex temperature control equipment, thereby resulting in a bending process and apparatus which are economical.
Terminology In the following description, the term shape is often used to refer to a rigid synthetic thermoplastic element which, in cross-section, is other than flat so as to have structural properties. The term shape is used in the same context as the word shape is used to describe rolled steel angles, channels, and l-beams for example, as opposed to flat bars.
DESCRIPTION OF THE'DRAWINGS The aforementioned and other features of this invention and more fully set forth in the following detailed description presented with reference to the presently preferred embodiments of the product, process and apparatus comprehended by the invention, which description is presented with reference to the accompanying drawings wherein:
FIG. 1 is an elevation view of the exterior side of a window according to this invention;
FIG. 2 is an elevation view of the interior side of the window shown in FIG. 1;
FIG. 3 is an elevation view of the exterior side of an openable multi-pane window according to this invention;
FIG. 4 is an enlarged cross-sectional elevation view taken along line 44 in FIG. 3;
FIG. 5 is an enlarged cross-sectional elevation view taken along line 55 in FIG. 3;
FIG. 6 is a cross-sectional elevation view of the frame members of another window according to this invention and shows one manner of mounting a window according to this invention in a window opening;
FIG. 7 is a cross-sectional elevation view similar to that of FIG. 6 showing another manner of mounting a window according to this invention in a window opening;
FIG. 8 is a cross-sectional elevation view through the frame member of still another window according to this invention and illustrates a third manner of mounting a window according to this invention in a window opening;
FIG. 9 is an elevation view of the exterior side of a frame member of another window according to this invention;
FIG. 10 is a top plan view of a rigid bending die according to this invention;
FIG. 11 is an enlarged cross-sectional elevation view of a rigid bending die;
FIG. 12 is a top plan view of another rigid bending die and clamping station according to this invention;
FIG. 13 is an elevation view taken along line 13-13 in FIG. 12;
FIG. 14 is an elevation view of a bending handle useful with the bending dies shown in FIGS. 11 and 12;
FIG. 15 is a perspective view of a flexible bending die according to this invention;
FIG. 16 is a bottom plan view of the bending die shown in FIG. 15;
FIG. 17 is a fragmentary top plan view of another flexible bending die according to this invention;
FIG. 18 is an elevation view of one end of the bending die shown in FIG. 17;
FIG. 19 illustrates a portion of the flexible die of FIG. 17 in its fully closed position;
FIG. 20 is a partially schematic diagram of an extrusion bending apparatus according to this invention;
FIG. 21 is a top plan view of another extrusion bending apparatus according to this invention;
FIG. 22 is an enlarged elevation view taken along lines 22-22 in FIG. 21;
FIG. 23 is a schematic diagram ofa multi-die bending apparatus according to this invention; and
FIG. 24 is a chart presenting the operational sequence which is presently preferred for the system illustrated in FIG. 23.
DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS An exemplary window according to this invention is shown in FIGS. 1, 2 and 6. The window includes a translucent pane 11; as used herein, the term translucent means either transparent or partially opaque as in frosted glass. The pane is received within an exterior frame member 12 to which an interior frame member 13 is mated. Window 10 has rounded corners l4 adapting it to be received in a correspondingly configured opening provided through the wall of the hull or deckhouse, for example, of a small boat. Preferably, pane 11 is defined by a piece of acrylic sheet resin the opposite surfaces of which bear an abrasion-resistant fluorocarbon coating; such sheet material is marketed by E. I. DuPont DeNemours & Co., Wilmington, Delaware, under the trademark ABCITE. If desired, however, the pane may be made of clear or tinted glass which may be transparent or partially opaque.
As will be described more fully below, frame members l2 and 13 for window 10 preferably are provided in halves during the manufacturing process, but in the finished window they are essentially integrally con nected, as by bonding, to appear functionally and structurally as a single element.
It is preferred that the exterior and interior frame members for a window of this invention be fabricated from bent extrusions of synthetic thermoplastic resin. The presently preferred thermoplastic resin from which the extruded frame members are fabricated is Geon 8700-A polyvinyl chloride resin obtainable from B. F. Goodrich Chemical Company, 3l35 Euclid Avenue, Cleveland, Ohio. This resin is referred to as a rigid" resin because it has a structural strength exceeding 10,000 psi. Geon 8700-A polyvinyl chloride resin has a structural strength of about 1 1,500 psi and has a heat distortion temperature at 264 psi of 157F. (see ASTM Standard Test Method D648-56).
As shown in FIG. 6 where members 12 and 13 are shown in transverse cross-section, the exterior frame.
member 12, as extruded, is a shape according to the foregoing definition. Thus, member 12 defines a web 18 which extends across the width of the extrusion. A pair of spaced parallel pane flanges 19 extend from one side of web 18 substantially perpendicular to the plane of the web. A third flange extends from the same side of the web as pane flanges l9 and is spaced from the adjacent one of the pane flanges. Flange 20 preferably has the same extent normal to the web as pane flanges l9. Flange 20 is provided to serve an ornamental function where the completed. window is a singlepane fixed-pane unopenable window, such as window 10; flange 20 also serves as a pane flange for a movable window pane in the case where the window is a multipane openable window such as window 21, shown in FIG. 3. The cross-sectional configuration of exterior frame member 12 also includes a mounting flange 22 which extends from the opposite side of the web, preferably at one edge of the web so as to be aligned with one of pane flanges 19; flange 20 preferably is aligned with the opposite edge of web 181. A plurality of stub flanges 23 extend from the same side of the web as mounting flange 22 and are spaced at regular intervals apart from each other over approximately one-half the width of the web. One of the stub flanges preferably is aligned with flange 20 and the remaining stub flanges are spaced so that the stub flange closest to mounting flange 22 is aligned with the pane flange 19 which is disposed intermediate the width of the web.
Also as shown in FIG. 6, the extruded shape for frame member 13 includes a web 25 and a flange 26 disposed perpendicular to the web along one edge of the web. An angle section is included in the crosssectional configuration of the inner frame member and is associated with the opposite edge of web 25. Accordingly, an angle section leg portion 27 extends normal to web 25 along the edge of the web opposite to the edge with which flange 26 is associated. An angle section flange portion 28 extends from the end of leg portion 27 remote from web 25 and extends from the leg portion in a direction away from flange 26. Therefore, flange 26 and leg portion 27 are disposed parallel to each other and extend in opposite directions from opposite edges of web 25. Web 25 and flange 28 of the angle section of the cross-sectional configuration of interior frame member 13 are disposed parallel to each other and extend in opposite directions from opposite edges of leg portion 27. Thus, in transverse crosssection, interior frame member 13 has a generally W- shaped configuration.
Exterior and interior frame members 12 and 13 preferably are provided as straight extruded shapes which are bent during manufacture of window 10 to a curvature appropriate to the radius of curvature appearing at the rounded corners of window opening 15. During the bending process, exterior frame member 12 is bent so that pane flanges 19 and flange 20 extend from the side of the web which is bent to assume a concave curvature. Similarly, the interior frame member extrusion is bent so that flange 26 extends from that side of flange 25 which is bent to assume a concave curvature. A preferred extrusion bending process and the preferred apparatus used therein are described in detail below following the description of the structures shown in FIGS. 1-9.
As shown in FIG. 1, frame member 12 preferably is defined by two pieces 29A and 298 each of which has opposite ends 30 and 31. The exterior frame member also is provided in two pieces. To facilitate assembly of the window, the exterior frame member extrusion preferably is bent as one piece and is thereafter cut in half, thereby to define pieces 29A and 298. On the other hand, pieces 29A and 29B may be bent separately from appropriate lengths of exterior frame member extruded stock material. To assemble the window, the pane, which has been precut with rounded corners, is inserted between the pane flanges of exterior frame member piece 29A and 298, for example, and the pieces are butted together. The frame pieces are then bonded together. Once pieces 29A and 298 have been connected, the pane is bonded, as at 32, to the frame, preferably to the pane flange which is aligned with mounting flange 22. This bonding preferably is accomplished by a solvent bonding process using a solvent effective upon both the synthetic material from which the exterior frame member extrusion is made and the synthetic material from which the pane is fabricated. In those cases where the pane is defined by ABCITE abrasion-resistant acrylic sheet material, it may be necessary to condition the pane around its edges by removing the fluorocarbon abrasion-resistant coating which characterizes this particular pane material. Tetrahydrofurane, especially when applied by a syringe, has been found to be a suitable solvent where acrylic and vinyl resins are to be bonded. Alternatively, conventional PVC glue may be used, if desired. In this manner, ends 30 and 31 of piece 29A are securedly connected to the corresponding ends of piece 298 so that, once the pieces have been connected to each other around a pane, the exterior frame member is effectively homogeneous around the entire periphery of the pane. Because of the cross-sectional configuration of the exterior frame member, it is apparent that this frame member does not readily flex, with the result that, in use, the bond between the exterior frame member and the pane is maintained.
As is apparent from FIG. 6, it is preferred that the spacing between the adjacent faces of pane flanges 19 be somewhat greater than the thickness of pane 11. Therefore, when the pane has been secured to the exterior frame member, a space exists peripherally of the pane between the pane and the adjacent surface of pane flange 19 to which the pane is not bonded. This space is filled with a suitable glazing material such as a silicon rubber. If desired, a strip of extruded flexible vinyl glazing strip may be forced between the inner surface of the pane and the adjacent pane flange. In this manner, a structurally sound and thoroughly weathertight connection is made between pane ill and the exterior frame member around the entireperiphery of pane 11 to provide a single-pane, fixed-pane permanently closed window assembly 10. Where a glass pane is used in a window according to this invention, it is preferred that the periphery of the pane carry a ,coating of some resin, such as vinyl butyrate, which adapts the glass for connection to the window frame by solvent bonding processes. For example, a ribbon of vinyl butyrate may be adhered to the periphery of a glass pane by applying heat and pressure via a tetrafluoroethylene pressure pad which withstands applied heat but does not stick to the vinyl butyrate. Tetrahydrofurane is a suitable solvent for bonding vinyl butyrate to polyvinyl chloride, for example.
The interior frame member extrusion is bent to mate closely with the exterior frame member in the completed window. As shown in FIG. 6, during bending of the interior frame member the extrusion thereof is bent to a curvature selected so that there is a clearance provided between the ends of stub flanges 23 of the exterior frame member and the face of interior frame member web 25 from which flange 26 extends. In completed window 10, the linear dimension from the face of flange 26 which opens toward web 25 to the unsupported end of flange 28 is selected with respect to the thickness of the wall or other structure in which window opening 15 is defined.
The curvature to which exterior frame member 12 is bent in manufacture of window 10 is selected so that, in the completed window assembly, stub flanges 23 may be passed through window opening 15, as shown in FIG. 6. It is preferred that before the exterior frame member is inserted into window opening 15, a bead of suitable caulking material is applied to the exterior surface of wall 16 immediately adjacent window opening 15. The exterior frame member, with the pane mounted therein, is then inserted into the window opening from the exterior of the structure until the mounting flange of the exterior frame member abuts the wall structure in overlying relation to the bead of caulking material. The interior frame member is then mated to the exterior frame member from the inside of wall 16 and is secured to the exterior frame member by means of screws 36. As shown in FIG. 2, the screws are provided at spaced locations around the periphery of the window and are passed through flange 26 of the interior framemember and through at least some of stub flanges 23 of the exterior frame member. Stub flanges 23 are provided so that screws 36 may be used effectively to connect the frame members and tightly clamp the wall 16 between mounting flange 22 and the end of flange 28, as shown in FIG. 6.
Where the above-described exterior frame member extrusion is used in the manufacture of a single-pane window, the channel defined in the exterior frame member by flange 20 adjacent pane flange 19 and web 18 serves no function. The portion of web 18 lying between flange 20 and the adjacent pane flange l9, and the stub flanges, are used to facilitate clamping cooperation between the exterior and interior frame members for mounting window 10 in window opening 15.
FIG. 3 is an elevation view of the exterior side of an openable multi-pane window 21 equipped with a screen 38. Window 21 is described with reference to FIG. 4, but as will be shown, a multi-pane openable window can be provided without a screen using the same extrusions as already described concerning window 10. Window 21 includes a fixed pane 39, a movable pane 40, and screen 38, all of which are mounted in an exterior frame member 41 which is shown in transverse cross-section in FIG. 4.
The extrusion for frame member 41 is similar to the extrusion for frame member 12 is that it includes a web 42 which defines the width of the frame member, a mounting flange 43, and stub flanges 44. Mounting flange 43 and stub flanges 44 extend from the same side of web 42 in association with opposite edges of the web. Thus, elements 42, 43 and 44 of frame member 41 are seen to correspond closely to elements 18, 22 and 23, respectively, of frame member 12. The extrusion for frame member 41 also defines three spaced pane flanges 45 and an additional flange 46', these elements correspond to elements 19 and 20 of frame member 12 except that in frame member 41 three pane flanges 45 are present. As in frame member 12, pane flanges 45 and flange 46 are of equal extent away from web 42 and are regularly spaced to extend perpendicular to the web from the side thereof opposite to the side from which flanges 43 and 44 extend. One of pane flanges 45 is coplanar with one of stub flanges 44, and flange 46 is coplanar with mounting flange 43. Also,
frame member 41 includes a stiffening element 47 which interconnects mounting flange 43 and web 42 intermediate the width of the web. The point of connection of the stiffening element to mounting flange 43, as at 48, preferably is no farther from the adjacent side of web 42 than the free ends of stub flanges 44. Thus, as in the case of frame member 12, the size of the window opening into which frame member 41 is fitted is determined with reference to stub flanges 44. Stub flanges 44 serve the same function in frame member 41 as do stub flanges 23 in frame member 12.
Fixed pane 39 bears a somewhat different relation to the sight opening of window 21 than does pane 11 to the sight opening of window 10. That is, in window 10, pane ll completely fills the sight opening of the win dow. (The sight opening is the clear viewing area of the window in its completed form.) In window 21, however, pane 39 fills only about one-half the sight area of the window. Thus, pane 39 has two rounded corners 49 and a straight edge 50 which, in the completed window, is disposed vertically at about the middle of the window. Movable pane 40 has rounded corners adapted to mate intimately with the exterior frame member of window 21 when the movable pane is in its closed position relative to the fixed pane as shown in solid lines in FIG. 3. Movable pane 40, however, has a length along the width of the window which is slightly greater than the length of the sight area of the window not filled by pane 39. Accordingly, movable pane 40 has an edge 51 which, when the movable pane is disposed in its closed position relative to the fixed pane, is disposed adjacent fixed pane edge 50 but between such edge and the opposite end of the fixed pane. The movable pane is slidable within exterior frame member 41 beween the closed position shown in solid lines in FIG. 3 and an opened position shown in broken lines in FIG. 3. The opened position of the movable pane is limited by the point at which the movable pane begins to interfere with the exterior frame member adjacent the rounded corners 49 of the fixed pane.
As shown in FIG. 4, fixed pane 39 is mounted according to the above-described techniques and methods between those two pane frames 45 which lie closest to and adjacent mounting flange 43. Preferably the fixed pane is bonded, as at 53, to the pane flange which lies outwardly of the width of the web. Glazing material 54, such as silicon rubber or an extruded flexible glazing strip is provided between the pane and the pane flange closest to the inside edge of web 42 in the completed window.
Movable pane 40 is mounted between the pane flanges disposed most centrally of the width of web 42. The mounting of the movable pane to the exterior frame member is by means of a flexible glazing insert molding 56 which is fabricated of resilient material such as a flexible vinyl resin, neoprene rubber or some other suitable weather-resistant elastomer. It is also conventional to use a rubber insert molding which has been flocked to provide a low coefficient of friction relative to the movable pane. The glazing molding 56 defines a plurality of resilient fingers 57 which bear against opposite faces of the movable pane and effectively provide a seal between the exterior frame member and the movable pane. The glazing molding is mounted in the exterior frame member so that, when the movable pane is in its closed position, it engages the rounded end of the movable pane and the adjacent elongated side edges of the movable pane; the glazing molding also extends sufficiently along the inner frame member toward the rounded end of fixed pane 39 that, during motion of the movable pane throughout the entire range of movement afforded to it within the window, the elongate side edges ofthe movable pane cooperate with the flexible glazing. As shown in FIG. 4, movement of the movable pane within the flexible glazing is facilitated by incorporating a strip of selflubricating bearing material 58 within the flexible glazing adjacent frame member web 42 for cooperation with the adjacent elongate side edge of the movable pane. The self-lubricating bearing material may be fabricated of tetrafluoroethylene, polyethylene or polypropylene, for example. On the other hand, a flocked rubber insert molding may be used if desired.
From the foregoing description, it is apparent that in window 21 the opposing faces of the fixed and movable panes of the window are spaced from each other by a distance which is essentially equal to the thickness of (1) one of pane flanges 45, (2) a distance equal to the distance by which the movable pane is supported from the adjacent pane flanges by flexible glazing molding 56, and (3) the distance between the fixed pane and the central pane flange. This space is effectively scaled between the movable and fixed panes along edge 50 of the fixed pane by a seal element 60, shown in FIG. 5. The seal element preferably is fabricated of a flexible elastomeric material such as flexible vinyl, neoprene rubber or the like, and is carried by the fixed pane along straight end edge 50 thereof. The fixed pane is received in a groove 62 formed in the seal element. The seal element also defines a flexible resilient lip 63 along its length, the end of which movably bears against the adjacent face of fixed pane 39.
A screen assembly 38 is also mounted within exterior frame member 41 and extends across approximately the same fraction of the sight area of window 21 as does movable pane 39. The screen assembly includes a piece of woven wire mesh 65 having its periphery supported in a channel 66 defined in a frame element 67 which extends circumferentially of the mesh. The mesh is held in the frame element by filling the channel with a flexible glazing material 68, such as silicon rubber, which imbeds the mesh and bonds to both the mesh and the walls of the channel. Preferably a rubber grommet (or a bead strip) 69 is disposed between each wall' of the channel and the adjacent face of the mesh and is bonded in place by the flexible glazing for the screen assembly. Frame element 67 for the screen assembly preferably is fabricated of a substantially rigid synthetic resin and preferably is merely positioned but not fixed in the channel between flange 46 and the adjacent one of pane flanges 45 of exterior frame member 41. The screen is slidable in the channel provided in frame member-41 between flange 46 and the adjacent pane flange in the same manner and over the same distance as the movable pane is slidable in the frame. As shown in FIG. 5, the portion of frame element 67 which lies adjacent edge 50 of the fixed panel when the screen is in its closed position is effectively sealed to the adjacent surface of the movable pane by a seal strip 64. The seal strip is carried by element 67 and preferably is a strip of polyurethane foam material which is lightly compressed between element 67 and the movable pane.
In accordance with the foregoing description concerning window 10, it is preferred that exterior frame member 41 be provided in two pieces which are bonded together to form an essentially unitary member after the fixed pane, the movable pane, and the screen assembly have been inserted into their respective channels.
Preferably, solvent bonding of the fixed pane to one of the two pieces of the exterior frame member, and of the other piece of the exterior frame member to the fixed pane and to the other half of the exterior frame member, is facilitated by using a hypodermic syringe, or the like. A suitable solvent, such as tetrahydrofurane, is placed in the syringe. The needle of the syringe is put into or adjacent to the space at which solvent welding is to be produced. The solventis then injected into this space as the needle is drawn through or along the space.
A complete window 21 of the type shown in FIGS. 3 and 4 also includes an interior frame member (not shown) which is similar to interior frame member 13 of window except that angle section flange portion of the interior frame member for window 21 is longer than the corresponding feature of interior frame member 13 by an amount equal to the difference between the web widths of frame members 41 and 12, assuming that window 21 is to be installed in the same thickness wall as is illustrated in FIG. 6. It will be appreciated that by varyingthe length of the flange portion 28 which is disposed parallel to the web of an interior frame member for a window according to this invention, the window may be adapted for mounting to a wall of substantially any thickness-encountered. In the case of camper trailers or the like, the wall panels may be up to 2 inches thick. In the case of thick walls, it may be expedient to eliminate flange portion 28 from the interior frame member (so that the interior frame member, in crosssection, resembles a rolled steel Z shape) and to reverse the relationship of the interior to the exterior frame member so that the wall is clamped between mounting flange 22 (or 43) and the leg portion 27 of the interior frame member; in such a case, the window opening in which the window is mounted must be sufficiently large that the web of the interior frame member may be disposed at least partially within the window opening.
In view of the foregoing description concerning FIGS. 4 and 6, it is apparent that a two-pane openable window not having a screen assembly 38 may be provided by using exterior frame member 12. In such a case, the movable pane of such a window is mounted in the channel defined between flange and the adjacent pane flange 19.
FIG. 7 is a transverse cross-section view through the exterior and interior frame member 70 and 74 of another window according to this invention. Exterior frame member 70 includes several of the features of frame member 10 previously described with respect to FIG. 6; therefore, to the extent that frame members 10 and 70 have common features, common reference numerals are used. Frame member 70 differs from frame member 10 by the deletion in frame member 70 of stub flanges 23. The mounting function provided by stub flanges 23 of frame member 10 is provided, in part, by a connection web 71 of frame member 70. Connection web 71 extends parallel to web 18 from mounting flange 22 in spaced relationship to the side of web 18 12 opposite from which flanges 19 and 20 extend. The
spacing of connection web 71 from web 18 is approximately equal to the thickness of web 18. (Webs 18 and 71 are of about equal thickness.) The width of connection web 71, i.e., the dimension of the connection web normal to mounting flange 22 and parallel to the width of web 18, is slightly less than the distance between the opposing faces of flange 20 and mounting flange 22. The face of connection web 71 which opens to web 18 defines a plurality of serrations or teeth 72 which are asymmetrical in the manner shown in FIG. 7, i.e., the teeth tend to slant toward mounting flange 22 rather than toward the opposite unsupported edge of the connection web. Exterior frame member preferably is used in combination with an interior frame member 74 which has a web 75. Web 75, when the interior frame member is viewed in cross-section as in FIG. 7, is straight and has a width which is less than the width of web 18 of exterior frame member 70. Interior frame member 74 also includes a flange 76 which extends from one side of web 75 along one edge thereof and which is arcuately curved so that its unsupported end 77 is disposed adjacent the opposite edge of web 75 but is spaced therefrom. Flange 76 is arranged so that the terminal portion of the flange adjacent end 77 extends parallel to web 75. The surface of web 75 which is disposed toward the unsupported end 77 of flange 76 defines a plurality of serrations or teeth 78 configured to mate with the serrations 72 defined by connection web 71 of the exterior frame member. Web 75 has a thickness which, making allowances for the presence of the serrations thereon, is equal to the spacing of connection web 71 from web 18 of exterior frame member 70.
Exterior frame member 70 may be used in the construction ofa single-pane, fixed-pane window similar to window 10, or in the construction of a multi-pane unscreened window similar to window 21, both of which have been described above with respect to FIGS. 1 and 3, respectively.
A window incorporating exterior frame member 70 is inserted into a window opening 15 defined in a wall structure 16 from the exterior side of the wall according to the preceding description; such a window opening must be sized to permit the passage of connection web 71 at least partially through the window opening, as shown in FIG. 7. The mounting of the window to wall structure 16 is accomplished by inserting the web 75 of mating and correspondingly bent frame member 74 into the space provided between web 18 and connection web 71 of frame member 70. The interior and exterior frame members are then pushed together so that web 75 of the interior frame member advances toward mounting flange 22 of the exterior frame member within the spaced between webs 18 and 71 of the exterior frame member. Such engagement of the interior frame member to the exterior frame member is facilitated by the cooperating slope of serrations 72 and 78, and is continued until the unsupported end 77 of exterior frame member flange 76 abuts the interior surface of wall structure 16 circumferentially of window opening 15. In this manner, the window is secured in the window opening by being clamped between the interior and exterior frame members. The configuration of serrations 72 and 78 prevents disengagement of the interior and exterior frame members.
As with the windows previously described, it is presently preferred that frame members 70 and 74 be fabricated from extrusions of rigid synthetic resin, a presently preferred resin being B. F. Goodrich Chemical Company Geon 8700-A rigid polyvinyl chloride resin.
FIG. 8 is a transverse cross-sectional elevation view through the single frame member 80 of another window according to this invention. Preferably frame member 80 is fabricated from a straight length of extruded rigid polyvinyl chloride bent to the desired curvature pursuant to the method described below. Frame member 80 is particularly useful in the manufacture of windows adapted for mounting in thin wall structures 81 within a window opening 82 defined therein. The crosssectional configuration of frame member 80 includes a web 83 which defines the width of the extrusion. It also includes a pair of pane flanges 84 and an additional flange 85, all of which are spaced substantially regularly from each other and which extend parallel to each other from one side of web 83. One of the pane flanges and flange 84 are disposed along opposite edges of the web. Flanges 84 and 85 all have the same extent normal to web 83. Frame member 80 also includes a mounting flange 86 which extends perpendicular to web 82 from the side of the web opposite to the side from which flanges 84 and 85 extend. Preferably mounting flange 86 is disposed substantially midway between the opposite edges of web 83.
It will be apparent from an inspection of FIG. 8 that frame member 80 may be used to advantage to define either a single-pane, fixed-pane unopenable window, similar to window 10, or a multipane openable window not including a screen but otherwise similar to window 21 shown in FIG. 3.
A window incorporating frame member 80 may be mounted in window opening 82 by means of a mounting and sealing member 88. Preferably the sealing member is fabricated of a flexible elastomeric material such as a flexible vinyl resin, neoprene rubber, or the like. Also, the mounting and sealing member may be provided as a closed loop resembling an enlarged O- ring, or as a strip of material which is cut to the appropriate length andfitted to thin wall 81 around window opening 82. Member 88, as shown in FlG. 8, is substantially rectangular in transverse cross-section, and defines a pair of aligned grooves 89 and 90 extending toward but not to each other from opposite edges of the member. Groove 89 has a width which is slightly less than the thickness of wall 81. Groove 90 has a width which is slightly less than the width of mounting flange .86 and preferably has a depth somewhat greater than the depth of the mounting flange. Frame member 80 of the completed window is secured in window opening 82 by first engaging the mounting and sealing member to the wall peripherally of the opening by seating the wall adjacent window opening 82 in groove 89. Thereafter, relying on the flexibility of the material from which the mounting and sealing member is fabricated, mounting flange 86 of the window is engaged in groove 90. In this manner, a secure and weathertight mounting of the window within window opening 82 is accomplished.
FIG. 9 is an exterior elevation view of another window 95 according to this invention. Window 95 is shown to illustrate the point that a window according to this invention need not be generally rectangular in configuration. Window 95 has a generally trapezoidal overall configuration and the slight area 96 of the window similarly has a generally trapezoidal configuration 14 with rounded corners 97, 98, 99 and 100. The frame of window 95 is fabricated from an extrusion of rigid thermoplastic resin (preferably a rigid vinyl resin) which has been bent to the desired configuration. Thus, the frame of window 95 includes two bends of a first selected radius which define corners 97 and 98 of the sight area. The frame also includes a third bend of substantially the same radius as the bends defining corners 97 and 98, but which subtends an arc of less than 90. Finally, the frame includes a fourth bend, corresponding to corner 100, which has a radius less than the radius of corner 97, for example, and for which the extruded frame material must be bent through an angle greater than 90.
FIG. 9 also illustrates that the frame of window preferably is provided in two pieces 101A and 1018, each of which has aligned ends disposed preferably along the parallel sides of the window, but which, during the manufacturing process, are interconnected to define an essentially integral frame for the window.
It is a feature of this invention that the frame members for the window contemplated. hereby may be fabricated of a thermoplastic resin which itself defines the color desired for the completed window. Thus, a window according to this invention "need not be painted. Also, the thermoplastic materials from which the frames are fabricated are not susceptible of corrosion. In presently preferred windows according to this invention, the frame members for the windows are defined by off-white extruded rigid polyvinyl chloride resin.
It is apparent from the foregoing description that windows according to this invention possess the advantages and benefits encountered in windows having extruded or stamped metal frames, yet they possess none of the disadvantages of windows having frames fabricated of vacuum-formed synthetic resin. Windows according to this invention may be provided in any configuration and in any frame color desired. Also, where the window is fabricated according to the following manufacturing processes, the window may be produced at low cost.
In the preceding description, reference has been made to extruded rigid polyvinyl chloride resin as a presently preferred material for the window frame members. This material is presently preferred largely because it is readily available at reasonable cost and can be formed in the manner contemplated by the following description of a method for bending complex shapes fabricated of thermoplastic resin. Those skilled in the art will readily appreciate that where these fabrication processes or other fabrication processes are employed, depending upon the properties of the particular resin, thermoplastic resins other than polyvinyl chloride may be used to provide extruded frame members for windows and the like according to this invention. Thus, this invention contemplates the provision of windows having frame members made of bent extrusions made of the following resins, among others:
acrylonitrile-butadiene-styrene :resins acetal homopolymers and copolymers acrylic resins chlorinated polyether resins polyvinylidene fluoride resins methylpentene polymers nylon resins polyarylsulfone resins polypropylene high impact polystyrene styrene-butadiene resins polysulfone resins high density polyurethanes and polyethylenes Also, this invention, as it pertains to the bending methods described below, contemplates that these resins may be encountered in the elements, preferably extruded elements, to be bent.
FIGS. 10-23 illustrate various mechanisms, apparatus and systems useful in bending to the desired curvature extruded frame members of the type described above concerning windows 10, 21 and 95, for example. Because the window structures described above preferably incorporate frame members fabricated of bent rigid vinyl extrusions, the structures and procedures illustrated in FIGS. 10-24 have been developed to implement the manufacture of such windows and are described in furtherance of a full and complete explanation of this invention, one aspect of which is the provision of these windows. It will be understood, however, that the bending structures, systems and features described below may be used to advantage in bending elements of complex cross-sectional configuration fabricated of thermoplastic resin whether or not such elements originally are produced by extrusion processes and whether or not such elements are to be used in windows or in some other product. Accordingly, this invention, in terms of the methods and procedures described below, and in terms of the apparatus for implementing such methods and procedures, contemplates that the thermoplastic elements to be bent may be fabricated by casting techniques, for example, as well as by extrusion. For the purposes of example, the methods,
procedures, structures and systems illustrated in FIGS. 1024 are described with reference to the bending of an extruded rigid polyvinyl chloride member having a cross-sectional configuration corresponding to the cross-sectional configuration of exterior frame member 12 shown in detail in FIG. 6 and described with reference thereto; this fact should not be regarded as restricting the use of these procedures and structures to the manufacture of windows such as the windows described above.
Briefly summarized, an elongate member of complex cross-sectional configuration, i.e., a shape as defined above, fabricated of rigid thermoplastic resin, is bent to a desired configuration while the cross-sectional configuration of the member is maintained over the arc of the bend. The shape is bent first by engaging a major portion of the cross-sectional configuration of the shape intimately with a bending die which is cooperatively configured to mate closely with the shape and to preserve the cross-sectional configuration thereof during the bending process. As mated with the bending die, the shape is heated, preferably by the application of a heating fluid directly to the shape via the bending die. The shape is heated to a temperature which is sufficiently elevated above ambient temperature that the thermoplastic material softens so as to lose a portion, but not all, of its rigid characteristics. That is, the shape, over the portion of the length thereof to be bent, is heated to a temperature which causes the thermoplastic material of the shape to soften and to lose a portion, but not all, of its tensile strength. Preferably, the temperature to which the shape is heated is a temperature which lies between the deflection temperature of the resin at 264 psi and the compression molding temperature for the resin. The bending die defines the curvature to which the shape is to be bent. Before the shape is actually bent to conform to the curvature of the bending die, a flexible second bending die is engaged with the remainder of the cross-sectional configuration of the shape. The flexible second die is then moved toward the first bending die, thereby to move the shape into intimate mating engagement with both dies over the length of the shape to be bent. The engagement of the shape between the bending dies is sufficiently forceful that the cross-sectional configuration of the shape is maintained during the bending process. Before the dies are separated from each other, the bent shape is cooled sufficiently to restore the sufficient tensile strength to the shape that the bent shape can be handled without distortion, and then the bent shape is removed from its engagement with the bending dies.
As shown in FIGS. 10 and 11, a stationary rigid bending die is mounted in the upper surface 106 of a support 107. Preferably, surface 106 is defined by a layer oflaminated phenolic sheet material 108 (such as Formica-brand surfacing sheet material) bonded to a piece of wood 109 which is relied upon to define support 107. Laminated sheet material is preferred as the upper facing of support 107 because, in a presently preferred bending procedure, saturated steam is used as the heating fluid for the element to be bent and tends to condense on the upper surfaces of the support.
Bending die 105 preferably is provided in the form of a hollow, cylindrical metal drum having a center cavity 110, an upper end 111 and a lower end 112. Cavity opens to die lower end 112, but not to die upper end 111. The exterior surface 122 of the die is formed to mate closely with a portion of the cross-sectional configuration of a thermoplastic member, such as exterior window frame member 12, to be bent. During the bending process, frame member 12 is intimately received with the exterior of the drum between an upper circumferential flange 113 and a lower circumferential flange 114 which extend parallel to each other radially of the axis 115 of the die. The die is mounted within a recess 116 formed in support 107 and so configured that the upper surface 117 of die lower flange 114 is coplanar with upper surface 106 of the support. The spacing between flange surface 117 and the lower surface 118 of upper flange 113 is only slightly greater than the width of frame member 12.
To facilitate intimate engagement of exterior frame member 12 with the circumference of die 105, three circumferential grooves are formed in die surface 122 between flanges 113 and 114. Accordingly, a first groove 119 is formed circumferentially of the die immediately adjacent surface 118 of upper flange 113 in such a manner that an extension of surface 118 forms one boundary of the groove. A second groove 120 is formed in the die surface 122 essentially midway between flanges 113 and 114, and a third groove 121 is formed immediately adjacent surface 117 of flange 114 in such manner that flange surface 117 forms one boundary of groove 121. As is readily apparent from FIG. 11, grooves 119, 120 and 121 are adapted to receive flanges 20, 19 and 19, respectively, of exterior frame member 12. Therefore, the grooves have a width (i.e., a dimension parallel to die axis 115) equal to the thickness of the corresponding flanges of the exterior frame member. Grooves 119, 120 and 121, however,
have a depth, i.e., a dimension radially of the die inwardly from die convex surface 122 (the same being a right circularly cylindrical surface) which is a small se lected amount greater than the extent of flanges 19 and 20 from web 18 of exterior frame member 12. Accordingly, as shown in FIG. 11, exterior frame member 12 is adapted to be intimately engaged with and mated to die 105 over a substantial portion of its cross-sectional configuration. As is apparent from the illustration in FIG. 11, die flanges 113 and 114, when the exterior frame member 12 is engaged to the die, extend radially outwardly beyond the adjacent portions of the exterior frame member. Die convex surface 122 has a radius of curvature which corresponds to the radius of curvature to which web 18 of exterior frame member 12 is to be bent so as to assume concave curvature.
Bending die 105 is defined of a metal which has high thermal conductivity. Aluminum has been found to be a suitable die material since it readily conducts heat and is readily machined to the desired configuration.
A thermally insulative liner 125 is disposed within cavity 110 of die 105 as shown in FIG. 11. The liner may be fabricated of heat resistant phenolic resin or the like, if desired. The liner has a cylindrical portion 126 which is engaged with the walls of cavity 110 from the upper end of the cavity to the lower end of the cavity around only a portion of the circumference of the cavity. The liner also has a radial flange 127 at its lower end which is engaged within recess 116 with the under- 7 side of die member flange 114. Liner flange 127 encompasses the same are around die 105 as does the liner cylindrical portion.
Referring to FIG. 10, assume that exterior frame member 12 is to be bent through an are 129 of 90 by use of bending die 105. The portion of the circumference of cavity 110 which is not covered by cylindrical portion 126 of liner 125 subtends an are 130 which is greater than are 129. The value of are 130 may be on the order of H0", for example. As shown in FIG. 10, arcs 129 and 130 are arranged so that arc 129 is centered within are 130. The function of liner 125 is to insulate the portion of the die member which lies outside of are 130 from the heating action of heating fluid introduced into cavity 110 via a heating and cooling fluid inlet duct 132, which communicates through support 107 to cavity 110. It is desired, primarily because of considerations of thermodynamic efficiency and the elimination of safety hazards to personnel using bending die 105, that only the portion of die 105 lying within arc 130 be heated during use of the bending die. It is apparent, therefore, that it is within the scope of this invention that only the portion of bending die 105 defined within are 130 need be made of thermally conductive material such as metal, and that the remainder of the circumference of the bending die may be made of some insulative material such as wood or Bakelite phenolic resin, if desired.
Preferably, duct 132 is relied upon to conduct both a suitable heating fluid to cavity 110 and, at different intervals during the bending of exterior frame member 12, to conduct a suitable cooling medium to cavity 110. Accordingly, duct 132 preferably is one leg of a Y connection 133. A heating fluid supply conduit 134 and a cooling. medium supply conduit 135 are connected to respective ones of the other legs of Y connection 133.
In a presently preferred bending system according to this invention, the heating fluid supplied to die member is saturated steam, which condenses within cavity and recess 116 of support 107. To facilitate drainage of condensed steam from recess 116, a drain tube 136 communicates through the bottom of support 107 to the lowermost extremities of recess 116.
A piece of rigid, thermally insulative material 137 is secured to the upper end of die member 105 and carries a bearing plate 138 from which a spindle 139 extends upwardly along axis of die 105. Spindle 139 is provided to define the fulcrum point for a bending handle assembly 140, described in detail below. In use of the apparatus illustrated in FIG. 11, the bending handle assembly bears against and is supported by bearing plate 138.
A flexible bending die 142 for use in cooperation with bending die 105 and exterior frame member 12 is.
shown in FIGS. 11, 15 and 16, as well as in other figures. Flexible die 142 preferably is defined by an elongate piece of hard rubber or similar material having a generally rectangular cross-sectional configuration. Accordingly, flexible die 142 has a top face 143, a bottom face 144 (see FIG. 16), a front face 145, and a rear face 146. The distance between top and bottom faces 143 and 144 of the flexible die is slightly greater than the distance between lower surface 118 of rigid die flange 113 and that surface of mounting flange 22 of exterior frame member 12 which is not engaged with die member flange 114 when the exterior frame member is intimately engaged with die member 105, as shown in FIG. 11. That is, the height of the flexible die member is selected relative to the dimensions of exterior frame member 12 such that, when the exterior frame member is mated to rigid die member 105, the flexible die member must be forced into the position shown in FIG. 11 between the exterior frame member and flange 113 of rigid die 105.
As shown in FIGS. 11 and 15, the front face 145 of the flexible die is configured to mate intimately with substantially all of that portion of the cross-sectional configuration of exterior frame member 12 which is not engaged by rigid die member 105 when the exterior frame member and the rigid die member are mated and frame member 12 has been bent "to the desired curvature. That is, the configuration of the flexible die is such that the flexible die deforms to the cross-section of member 12 as bent, rather than from the initial cross-section of member 12 prior to bending. Accordingly, four elongate grooves 148 are defined parallel to each other within face 145. One of grooves 148 is defined jointly in front face 145 and top face 143 of the flexible die. The width of each of grooves 148 is equal to the width of each of stub flanges 23 of exterior frame member 12, and the depth of each groove 148 is equal to the extent of stub flanges 123 from the adjacent surface of web 18 of the exterior frame member. Similarly, the spacing between adjacent ones of grooves 148 is equal to the spacing between adjacent ones of stub flanges 23. Accordingly, flexible die 142 is readily matable with exterior frame member 12 in the manner illustrated in FIG. 11.
In a preferred bending procedure practiced according to this invention in connection with exterior frame member 12, it is preferred that the exterior frame member be heated over the portion of its length to be bent by heating fluid applied directly to the exterior frame member through flexible die 142. Accordingly, a bore 150 (see FIG. 11) is provided along a portion of the