Abstract:
A high impact resistant rotationally molded door and process for molding the door is disclosed in which a hinge member is integrally molded to the door along one edge only. This hinge member forms to the hollow door edge without door warpage during curing and shrinking of rotationally molded plastic door body. Door warpage is avoided by delaying full integral attachment of the hinge member to the door until curing of the injected foam interior which both bonds to the interior of the door and the hinge member. An improved seal and hinge seal is disclosed together with a placed window construction that can include both placement and shaping to meet the special order needs. Further improvements including the expedient of venting a rotationally molded door during the rotational molding process through an integrally molded hinge edge reinforcing member. This same venting scheme is utilized for enabling improved cooling of the door once molding of the hollow door shell has occurred. Further, the rotationally molded door keys with improved efficiency to subsequently injected foam at the manifold outlets.

Description:
This application is a Continuation-in-Part of application Ser. No. 08/299,990, filed Sep. 1, 1994, now U.S. Pat. No. 5,528,865. 
    
    
     This invention relates to an improvement on a hollow rotationally molded and foamed filled high impact resistant insulated door. Specifically, a molded door is disclosed which includes a hinge bar integrally molded to the plastic door to both simplify door construction and obviate through bolting of cast hinge members to the finished door product. An improved air barrier is disclosed for use with the door to provide an air barrier in the vicinity of the integrally attached hinge member as it protrudes at the corners of the door adjacent the edge of the integrally molded hinge member. 
     This Continuation-In-Part Application sets forth further improvements including the expedient of venting a rotationally molded door during the rotational molding process through an integrally molded hinge edge reinforcing member. This same venting scheme is utilized for enabling improved cooling of the door once molding of the hollow door shell has occurred. Further, the rotationally molded door keys with improved efficiency to subsequently injected foam at the manifold outlets. 
     BACKGROUND OF THE INVENTION 
     In Brown U.S. Pat. No. 4,084,347 issued Apr. 18, 1978 entitled HIGH IMPACT RESISTANCE DOOR, there is described a rotationally molded hollow body door which is foamed-in-place in the interior of the hollow door with insulating material. A gasket construction is shown molded into the door edges. 
     This door requires the use of an integral two part mold which anticipates window placement. Further, reinforcing members are inserted through cuts within the rotationally molded structural skin of the door after rotational molding but before foaming to inhibit door warpage. After foaming, and during completion of the door assembly, the structural skin of the door is again cut at the door hinge corners and cast and molded hinge members are placed on the door. While the disclosed door is of sturdy construction, what follows is a simplified construction method and resultant door having greater flexibility, lower cost and higher commercial applicability. 
     In the rotational molding of doors, it has been required to vent molds during the rotational molding process. Specifically, an aperture is placed in the rotational mold typically in the vicinity of the hinge recess in the upper and lower hinge corners of the door. Because such vents have a tendency to discharge unconsolidated powder plastic charges placed within the rotational mold, such vents are filled with glass fibers. These fibers enable the desired venting to occur without permitting excessive release of the unconsolidated powder plastic charge--especially during the early stages of the rotational molding process. 
     When cooling of a rotational mold is desired, the vent tubes are typically removed. During the cooling of the mold, air can enter the otherwise hollow part preventing collapse due to atmospheric pressure. 
     We have fabricated doors utilizing the rotational molding process. In our fabrication process, we utilize the holes of the vent tubes as an entry point for routing out apertures for the insertion of steel members to our rotationally formed doors. Specifically, and for our most robust industrial doors, we route square apertures having a cross section sufficient to fit the corresponding square cross section of a steel bar inserted along the hinge side edge of the door. In this prior art construction, once these apertures are routed, a steel bar is threaded through the apertures along the door hinge axis and taped in place. After, this taping has occurred, the door is placed in a press with its hinge edge vertically upward and has foam injected to the hollow interior. Curing occurs in the mold. The tape holding the reinforcing bar is removed and conventional finishing assembly of the door follows. 
     SUMMARY OF THE INVENTION 
     A high impact resistant rotationally molded door and process for molding the door is disclosed in which a hinge member is integrally molded to the door along one edge only. This hinge member forms to the hollow door edge without door warpage during curing and shrinking of rotationally molded plastic door body. Door warpage is avoided by delaying full integral attachment of the hinge member to the door until curing of the injected foam interior which both bonds to the interior of the door and the hinge member. 
     A mold fabricated from back side reinforced aluminum sheet is disclosed. This mold has an interior for defining a hollow rotationally molded six sided door. A mold cavity is provided including a front door surface, a top door edge, a bottom door edge, a hinge door edge, and an opening door edge. The mold is closed and opened at a flat plat surface which also forms the rear door edge. When closed, the surfaces of the mold form an integral hollow cavity. Plastic, when placed into this hollow cavity and rotationally molded, forms a hollow plastic door body on the interior surface of the mold with the inner portion of the plastic door body being hollow. 
     The mold further defines an upper hinge cavity in the upper door corner in the front door surface, rear door surface, top door edge and hinge door edge. A lower hinge cavity is defined in the lower door corner by the mold in the front door surface, rear door surface, bottom door edge and hinge door edge. An elongate hinge member is placed in the mold extending along the hinge door edge within the integral hollow cavity of the door and extending into the upper hinge cavity and the lower hinge cavity. 
     A release agent coating is applied to extend interior of the integral hollow cavity of the door adjacent the upper hinge cavity and the lower hinge cavity. The portion of the hinge member in the middle of the door is left uncoated. In the preferred embodiment, the hinge member includes an attached protruding portion--such as hollow square bar--for secure attachment to the door when subsequently filled with foam. 
     Plastic is placed in the mold and rotationally molded. The plastic adheres to the interior surfaces of the mold to form a hollow plastic door body having the front surface, the rear surface, the top door edge, the bottom door edge, the hinge door edge, and the opening door edge with the upper and lower hinge member cavities defined in the door. Such integral bonding does not occur to the release agent coated portions of the hinge member adjacent the upper and lower hinge cavities. The door can then shrink relative to the hinge member during curing of the outer plastic body of the door. The result is that the rotationally molded hollow door is not warped or bent out of a plane configuration by the attached hinge member along only one edge of the door during curing and shrinking of the hollow plastic body of the door. 
     Thereafter, a foam filler is injected interior of the door integrally bonded within the integral hollow cavity of the door. At this time, the hinge member and its attached protruding portion integrally bond to the door. There results the simplified integral hinge member bonded to the finally fabricated foam enclosing door. 
     There is also disclosed an improved hinge seal for use with the door. Simply stated, and in the vicinity of the upper and lower hinge cavities, there is attached to the sill a semi-rigid arcuate member. This semi-rigid arcuate member mates with a door mounted channel contained within the hinge cavity. As the door opens and closes, an air seal is maintained between the semi-rigid arcuate member and channel, effectively providing an air barrier at the hinge recess. 
     In the Continuation-In-Part Application, we disclose a manifolded reinforcing side hinge edge member integrally formed with door at the hinge edge of the door. As before, mold release agent is applied to a typically square section manifolded steel bar placed through the rotational mold and extending out either end of the rotational mold. When rotational molding occurs, the manifold in square section steel bar forms a convenient gas escape path with a sufficient circuitous gas path to prevent discharge of substantial quantities of uncoalesced plastic powder charge. During cooling of the product in the mold, gas can enter through the manifolded hinge member to prevent collapse due to atmospheric pressure. Upon demolding of the product, cooling air can be introduced and expelled through the manifolded hinge edge reinforcing member to assure uniform part cooling without differential contraction that can lead to deformation of the molded part. Finally, and during the door foaming process, penetration of the foam to the interior of the square sectioned manifolded steel reinforcing bar indicates flooding of the door with a sufficient level of foam as well as enabling improved keying of the hinge edge reinforcing bar to the door through the foam. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a turret type station apparatus including a first station for loading the mold of this invention, a second station for the oven contained rotational molding of the loaded mold, a third station for the cooling of the mold; and a fourth station for unloading and storing the mold; 
     FIG. 2 is a perspective view of the mold only with the top plate shown in exploded relation overhead illustrating the placing and spreading of plastic within the mold and the integrally fastened hinge bar placed to the mold with the top and bottom areas of the hinge having mold release being differentiated from the rest of the hinge bar; 
     FIG. 3 is a view of the rotationally molded and removed door being injected with foam within a schematically indicated press to preserve the linearity of the door, the press here being illustrated including a group of doors; 
     FIG. 4 is a perspective view of a section of the door at the upper hinge corner having an edge for receiving a gasket shown with the inserted and replaceable gasket and illustrating a hinge member air dam channel adjacent the protruding integral hinge bar at the upper portion thereof; 
     FIG. 5 is a perspective view of the upper hinge corner shown in FIG. 3 with the hinge member air dam mounted to the door shill and co-acting with the hinge member air dam channel to provide insulation of the interval at the hinge to enable working insulation of the door at the hinge interval; 
     FIG. 6 is a perspective view of a window being installed to the foam filled rotationally molded door; 
     FIG. 7 is a perspective view of a completed and installed door according to this invention; 
     FIG. 8 is a detail of the mold of this invention at the integrally fastened hinge member illustrating the coating of the hinge member and its placement to the mold; 
     FIG. 9 is a view of an alternate cylindrical hinge edge reinforcing member which can be placed and subsequently through bolted between the door sides of the rotationally molded door; and, 
     FIGS. 10A and 10B are respective side elevation section and plan views of a rotational mold formed in accordance with this invention illustrating a manifolded hinge edge reinforcing member being placed for integral formation with the rotationally molded door shell, it being noted that spaced manifolding apertures along the edge of the door permit the entry and exit of gas from the door. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 7, door D is shown mounted to sill S along hinge axis A. Door D includes front surface 14, rear surface 24, and respective hinge edge 16, opening edge 18, top edge 20, and bottom edge 22. A single hinge member H is integrally molded to the hollow door body Y (the door body shown in FIG. 3). This hinge member H protrudes into upper hinge cavity 26 at the upper hinged corner of the door and lower hinge cavity 28 at the lower corner of the door. 
     Opening and closing of door D is conventional and can be easily understood. Specifically, bottom hinge member portion 30 protrudes into a conventional hinge bearing where hinge member H at bottom hinge member portion 30 can rise and fall as door D respectively opens and closes. Top hinge member portion 32 is conventionally attached to a conventional V-cam door closure mechanism. This mechanism causes the door D to raise upon opening, and descend upon closing against a conventional V-cam door closure mechanism. Such a mechanism can be obtained from Chase-Durus Industries of Bend, Oreg. under the product designation 5508. 
     It will therefore be understood that upper hinge cavity 26 and lower hinge cavity 28 are necessary so that door D can rise and fall during opening on hinge member H. This being the case, these respective hinge cavities must be prevented from venting air through sill S when door D is in the closed position. To prevent this from occurring, door attached U-shaped flange F and sill attached arcuate air stop R is utilized. 
     Having generally described the door product of this invention as installed, and description of the process of manufacture of door D can now be set forth. 
     Referring to FIG. 2, mold M for rotational molding of door D is set forth. The two major surfaces of door D including front surface 14 and rear surface 24 are molded across front surface aluminum sheet 44 and rear surface aluminum sheet 54. Each of these sheets is reinforce on the reverse side by longitudinal reinforcing members 45 and transverse reinforcing members 46, such reinforcing members only visible with respect to front surface aluminum sheet 44. 
     Rear surface aluminum sheet 54 has attached thereto U-shaped channels forming mold opening side edge 48, mold hinge side edge 50, mold top edge 51, and mold bottom edge 52. It will thus be seen that rear surface aluminum sheet 54 with its respective fastened edges forms cavity C into which plastic P can be placed for rotationally molding door D. It will be realized that when mold M is closed by front surface aluminum sheet 44 that hollow mold M will be formed. 
     It is required that hinge member H be integrally molded to hollow door body Y. To understand this feature of the invention, reference must be made to FIG. 8. 
     Referring to FIG. 8, hinge member H is shown placed interior of mold M. Hinge member H includes 11/4 inch diameter bar having square key section 55 welded thereto (See FIG. 2). Mold M defines an inner dimension of 11/2 inches. It is important that hinge member H having those portions of the bar adjacent upper hinge cavity 26 and lower hinge cavity 28 coated with release agent. 
     Accordingly, hinge member H at upper member section 56 and lower member section 58 is coated with release agent. As is conventional, the interior of mold M is also coated with a release agent. Medial portion 60 of hinge member H including square key section 55 is left uncoated. The effect of this release agent coating of upper member section 56 and lower member section 58 during conventional rotational molding is easy to understand. 
     Specifically, plastic P molds to all interior portions of mold M. Such molding of plastic will also occur around hinge member H at the borders of mold M. Molding of plastic will generally not occur to portions of hinge member H between upper member section 56 and lower member section 58. 
     Plastic attaching to hinge member H at upper member section 56 and lower member section 58 will be free to move. The result is that when rotational molding has occurred, hollow door body Y and hinge member H will form an integral linear member with only local attachment of hinge member H at those portions of hollow door body Y through which hinge member H protrudes. Final, integral attachment of hinge member H to door D will await filling of hollow door body Y with foam. 
     It will be understood that molding a member such as door D with integrally molded hinge member H has not heretofore been possible without significant warping of the molded member, here door body Y. Specifically, and in absence of both the release agent here utilized and the disclosed foaming sequence, such a single side member would cause door warpage upon curing of the door. 
     Referring to FIG. 1, rotational molding is relatively easy to understand. Schematically, a turret type multiple station rotational molding station 64 is illustrated. It includes mold loading station 70, mold rotating station 72, mold cooling station 74, and product discharge station 76. At the end of rotational molding, there is discharged hollow door body Y having hinge member H integrally molded thereto. 
     Typically, and after rotational molding of hollow door body Y, the door product is allowed to sit for a period of 24 hours. Thereafter, and as shown in FIG. 3, foam injections occur through aperture 80 and hose 82 from conventional foam producing apparatus (not shown). Such foam injection finally causes hinge member H to integrally bond to door D. 
     Once this has occurred, door D filled with foam is allowed to sit further for 24 hours. Thereafter, the respective hinge edge 16, opening edge 18, top edge 20, and bottom edge 22 are milled to receive gasket molding 85. As can be seen in FIG. 4, gasket molding 85 has door edge side 86 configured to fit to the milled door edges. Further, gasket molding 85 defines gasket receiving slot 87 to receive gasket 90 at the respective hinge edge 16, opening edge 18, top edge 20, and bottom edge 22. 
     Once gasket 90 has been installed, window W is placed in door D. Specifically, window hole 100 is first placed in door D and drilled with bolt apertures 101. Thereafter, front window flange member 104, and rear window flange member 105 trap window pane 106 therebetween. 
     In observing the installation of window W, it will be understood that placement of window W is independent of the construction of mold M. This being the case, the size, shape, and location of window W can be varied to suit customer preference on a special order basis. 
     It will be noted that door D includes an installed bumper B in FIG. 7. Such bumpers B are conventional; they will not be further discussed here. Having set forth the door construction, attention can now be devoted to still attached arcuate air stop R. 
     Referring to the perspective detail of FIG. 5, door D at upper hinge cavity 26 is illustrated. Door D on vertical cavity edge 110 includes U-shaped flange F. Sill S has fixed thereto sill attached arcuate air stop R. This sill attached arcuate air stop R fastens at first arcuate end 112 to sill S, extends around hinge member H, and fastens at second arcuate end 114 to sill S. In such extension, sill attached arcuate air stop R is given a length so that it contacts U-shaped flange F. Thus during opening and closing of door D, contact of sill attached arcuate air stop R with U-shaped flange F will continuously occur. 
     It will be remembered that door D rises and falls during respective opening and closing. This being the case, some provision at sill attached arcuate air stop R is desirable. Accordingly, slotted skirt 120 is placed adjacent the lower edge of upper hinge cavity 26. Similarly, a slotted skirt 120 is placed at the upper portion of sill attached arcuate air stop R on lower hinge cavity 28. It will be understood that at upper hinge cavity 26, conventional V-cam door closure mechanism is enclosed by sill attached arcuate air stop R. As this conventional V-cam door closure mechanism is conventional, it is not here illustrated. 
     It will be understood that a particularly advantageous door construction is illustrated. Over the prior art, both door construction and cost of manufacture are simplified and lowered. 
     Referring to FIG. 9, square stock hinge member H is shown in partial longitudinal section. As can be seen, square stock hinge member H&#39; is manifolded at apertures 101 and is open at its respective ends 102. Typically, square stock hinge member H&#39; is a 1&#34; by 1&#34; steel tube. 
     Referring to FIGS. 10A and 10B, placement of square stock hinge member H&#39; within mold M&#39; can be easily understood. square stock hinge member H&#39; is positioned relative to mold M&#39; so that manifold apertures 101 communicate to the interior of the mold and end apertures 102 communicate exterior of mold M&#39;. 
     Function of square stock hinge member H&#39; and its apertures 101 and open ends 102 during the molding process can be easily understood. First, and as in the previous embodiments, square stock hinge member H&#39; forms a manifolded reinforcing side hinge edge member. This side hinge edge member will be integrally formed with door at the hinge edge of the door. 
     As before, mold release agent is applied to the typically 1&#34; by 1&#34; square section manifolded steel bar placed through rotational mold M and extending out either end of the rotational mold. When rotational molding occurs, the manifold in square section steel bar forms a convenient gas escape path through apertures 101 and out ends 102 with a sufficient circuitous gas path to prevent discharge of substantial quantities of uncoalesced plastic powder charge. 
     Additionally, and during cooling of the product in the mold, gas can enter through square stock hinge member H&#39; to prevent collapse due to atmospheric pressure. 
     Upon demolding of the product, cooling air can be introduced and expelled through the manifolded hinge edge reinforcing member to assure uniform part cooling without differential contraction that can lead to deformation of the molded part. It is to be noted that the &#34;manifolded construction&#34; of square stock hinge member H&#39; effects a uniform distribution of cooling air interior of the recently molded door article; differential cooling which might otherwise warp of the door will be held to a minimum. 
     Finally, and during the door foaming process, penetration of the foam to the interior of the square sectioned manifolded steel reinforcing bar indicates flooding of the door with a sufficient level of foam as well as enabling improved keying of the hinge edge reinforcing bar to the door through the foam. Further, apertures 101 form points for square stock hinge member H&#39; to key to injected foam, further giving a sturdy door construction. 
     It is to be understood that square stock hinge member H&#39; will typically be through bolted to the rotationally molded door body.