Patent Publication Number: US-11376834-B2

Title: System for assembly of recessed panel doors

Description:
RELATED APPLICATION 
     This application is a divisional of and claims the benefit under 35 U.S.C. §§ 120 and 121 from U.S. patent application Ser. No. 15/260,593, filed Sep. 9, 2016, which claims the benefit under 35 U.S.C. § 119(e) from U.S. Provisional Patent Application No. 62/217,710, filed Sep. 11, 2015, both of which are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The field of the present disclosure relates to systems and methods for assembling doors. 
     BACKGROUND 
     A known method of assembling doors involves applying adhesive to an inside surface of two door skins; laying up a door assembly by stacking an internal frame and lightweight core material between the door skins; pre-pressing the door assembly to bring the adhesive into contact with the frame; and then feeding the pre-pressed doors into a separate heated press for curing the adhesive. Some such door skins include inwardly-contoured channels that simulate the sticking regions of a traditional solid wood door. 
     SUMMARY 
     In one embodiment, a system for making a door assembly from a stack of door components including first and second door skins, an internal frame, and a core, comprises a lower die section removably seated on a lower platen of a press and an upper die section removably attached to an upper platen of a press. At least one of the lower and upper die sections includes a base and one or more raised sections that stand off from the base to contact and support one or more recessed panel portions of the door skins during the pressing operation. The raised sections have a height above the base approximately equal to or greater than the depth of the recessed panel portions. 
     The upper and lower die sections are preferably made of a plastic material that is relatively soft and non-marring to reduce the possibility of damage to the door skins, and which is light weight to facilitate changing out the die sections for different sizes and styles of doors. 
     A method of making a door assembly includes seating a lower die section against a lower platen of a press, attaching an upper die section to an upper platen of the press, and positioning a door assembly within the press so that a raised section of the lower die section contacts the recessed panel portions of a first door skin of the door assembly. Thereafter, the method involves closing the press so that a raised section of the upper die section contacts the recessed panel portion of a second door skin of the door assembly, and pressing the door assembly between the upper and lower platens of the press with the recessed panel portions of the first and second door skins supported by the raised sections of the lower and upper die sections, respectively, so that the recessed panel portions press against the core of the door assembly to thereby compress and deform the core therebetween during pressing. 
     Additional aspects and advantages will be apparent from the following detailed description of preferred embodiments, which proceeds with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an isometric front view of a recessed-panel door, partially broken away to reveal an internal frame and expanded paper honeycomb core construction. 
         FIG. 2  is a schematic cross section view of the door of  FIG. 1  taken along line  2 - 2  of  FIG. 1  (not to scale). 
         FIG. 3  is a pictorial schematic illustration of a press system for pressing together components of a recessed panel door, illustrated partially. 
         FIG. 4  is a schematic elevation view of the press system of  FIG. 3 . 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       FIGS. 1 and 2  show an exemplary door  10 , made by the method and system disclosed herein. With reference to  FIGS. 1-2 , door  10  includes an internal frame  20  that extends around a perimeter of door  10  to define a cavity filled by a core  26 . A first (or front) door skin  34  overlays a front surface of frame  20  and core  26 . A second (or rear) door skin  38  ( FIG. 2 ) overlays a rear surface of frame  20  and core  26  opposite the front surface. First door skin  34  includes an inner surface  42  which faces core  26  and frame  20  and an outer surface  44  which forms the front surface of door  10 . Inner surface  42  is attached to the front surface of frame  20  by an adhesive. First door skin  34  preferably has a first planar portion  50  lying in a first plane. First planar portion  50  generally surrounds one or more recessed panel portions  56  (or panel regions) formed in first door skin  34 , and may present the appearance of conventional stiles and rails. Recessed panel portions  56  appear as shallow indented regions in the outer surface  44  of first door skin  34 , recessed relative to first planar portion  50 . Recessed panel portions  56  may have a rectangular shape and planar surface as shown, or may have other regular or irregular shapes and contours contributing to the overall aesthetic design of door  10 . Each recessed panel portion  56  may have a depth in the range of about 3-15 mm inwardly from first planar portion  50 , for example, and may have width W in the range of about 50 mm to 1 m (or more typically in the range of about 100 mm to 800 mm) and a height H in the range of about 100 mm to 2.5 m (or more typically in the range of about 200 mm to 2 m). Transition regions  58 , known in the art as “sticking” or simulated sticking, connect first planar portion  50  to recessed panel portions  56 . First planar portion  50 , panel portions  56 , and transition regions  58  are preferably formed in a unitary sheet of material, such as molded high density fiberboard, for example, that has a substantially uniform thickness throughout (but may be somewhat thinner at transition regions  58 ). One suitable door skin is made of a fiber composite material having a thickness in the range of about 1.1 mm to 6 mm, or 2 mm to 4 mm, or 2.5 mm to 3.5 mm. When first door skin  34  includes multiple recessed panel portions  56 , they are typically substantially co-planar in a second plane that is parallel to and spaced inwardly from the first plane of first planar portion  50 . The recessed panel portions  56  characterize door  10  as a recessed-panel door. 
     Similarly, second door skin  38  includes an inner surface  72  which faces core  26  and frame  20  and an outer surface  74  forming a rear surface of door  10 . Second door skin  38  is attached to the rear surface of frame  20  by an adhesive. In second door skin  38 , simulated stiles and rails comprise a second planar portion  80  lying in a third plane spaced apart from the first and second planes of first door skin  34 . Second planar portion  80  surrounds one or more recessed panel portions (or panel regions)  86  that are recessed relative to second planar portion  80 . Transition regions  88  (sticking), connect second planar portion  80  to recessed panel portions  86 . When second door skin  38  includes multiple panel portions  86 , they are typically substantially co-planar in a fourth plane parallel to and spaced inwardly from the third plane of second planar portion  80 . Recessed panel portions  86  may have similar dimensions in width, height, and depth as recessed panel portions  56  of first door skin  34 , or different dimensions and depth. In an alternative embodiment (not shown), one of the first and second door skins  34 ,  38  may have a different ornamental design, different contours, different sticking, or panel regions that are not recessed, or may be entirely flat (flush) and lacking simulated sticking entirely. 
     In a preferred embodiment, core  26  comprises an expanded paper honeycomb material, which has a relatively high strength to weight ratio, but which is crushable by the press systems and methods described below. For example, the expanded paper honeycomb material of core  26  may have a compressive strength in the range of about 1.0 kg force per square cm (kgf/cm 2 ) to about 15 kgf/cm 2  (100 kPa to 1470 kPa) or more typically in the range of about 4 kgf/cm 2  to about 8 kgf/cm 2  (390 kPa to 785 kPa). Other structural materials that can be crushed or compressed under sufficient pressure may also be used for core  26 , for example, expanded plastic film honeycomb material, corrugated cardboard, low density foam board, and others. Door skins  34 ,  38  are pre-formed in a door skin press process, including pre-forming recessed panel portions  56 ,  86  and transition regions  58 ,  88 . Adhesive (not illustrated) is applied between first door skin  34  and frame  20  and between second door skin  38  and frame  20  to bond the door skins  34 ,  38  to frame  20 . Frame  20  may be coated with adhesive before being stacked together with door skins  34 ,  38 . Alternatively, door skins  34 ,  38  may be coated in the region of frame  20  or over their entire surface so they also adhere to core  26 . 
     Methods of assembling door  10  will now be described with reference to an exemplary pressing system illustrated in  FIGS. 3-5 . Turning to  FIG. 3 , the system includes a press  100  (illustrated schematically) for pressing together components of a door  10 , so as to ensure positive contact between adhesive-coated surfaces of the internal frame  20  with door skins  34 ,  38 . The pressing operation also compresses the core  26  between the recessed panel regions  56  of door skins  34 ,  38 , as will be further described below. Subsequent to pressing in press  100 , the pressed door assembly may be transferred to a separate heated press for curing the adhesive, then trimmed, finished, and packaged for shipment or sale. 
     Press  100  includes a lower platen  110  and an upper platen  120 . In the embodiment illustrated, a workpiece transport and positioning subsystem  124 , described below with reference to  FIG. 4 , feeds a partially pre-assembled and stacked collection of door components  130 , laid flat, into press  100 . Door components  130  include first and second door skins  34 ,  38  stacked on either side of frame  20  and core  26 . The workpiece transport and positioning subsystem  124  aligns the door components  130  relative to the press  100 , and ejects the pressed door components  130  from the press  100  after pressing. For example, lower platen  110  may be segmented to accommodate tracks of a roller conveyor  134  ( FIG. 4 ) in channels or gaps  138  between segments  142  of lower platen  110 . In a preferred embodiment, the roller conveyor  134  and an alignment mechanism  146  of the workpiece transport and positioning subsystem  124  are moveable to align door components  130  with each other and relative to press  100  and then to retract, so as not to interfere with the pressing operation. 
     Press  100  includes a lower die  148  comprising one or more lower die sections (or lower jigs)  150  seated on lower platen  110 , and an upper die  158  comprising one or more upper die sections (or upper jigs)  160  attached to upper platen  120 . In the embodiment illustrated, the lower die  148  includes three lower die sections  150 , each of which is seated on one of the three segments  142  of lower platen  110 , and the upper die  158  includes one upper die section  160  attached to upper platen  120 . In other embodiments, a greater or lesser number of platen sections and/or die sections may be utilized. The lower die sections  150  are configured as a set, to collectively fit one or more particular door designs. Each of lower die sections  150  includes a base  170 , having a bottom surface (seating surface)  176  which rests on lower platen  110 , and at least one raised section  182  opposite bottom surface  176  and protruding from base  170 . Consistent with the configuration and proportions of recessed panel portions  56  relative to first planar portion  50 , each raised section  182  is generally narrower and shorter than base  170 , and therefore has a smaller surface area than base  170 . In the embodiment illustrated, each of the lower die sections  150  has multiple raised sections  182 , which are sized and arranged to support the multiple recessed panel portions  56  of first door skin  34  during pressing (which may sometimes span the gaps  138  during a pressing operation). Raised sections  182  have a height above base  170  corresponding to the depth of recessed panel portions  56  of first door skin  34  inwardly of first planar portion  50 . Each raised section  182  has a panel-supporting contact surface  194  opposite bottom surface  176  and facing away from lower platen  110 . In yet another embodiment, base  170  is omitted, such that each lower die section  150  comprises only a single raised section  182  directly attached to the lower platen  110  so that the exposed platen surrounds each such raised section  182 . Alternatively, base  170  may have a width and length that entirely underlie raised section  182 . 
     With reference to  FIG. 4 , in the embodiment illustrated, upper die section  160  of upper die  158  is secured to upper platen  120  by mounting bolts and T-nuts  202  captured within T-slots  204  in upper platen  120 , or by any other convenient means of securement. Similarly to lower die sections  150 , upper die section  160  includes a base  220  having a seating surface (top surface)  226  that is held adjacent upper platen  120 , and at least one raised section  230  opposite seating surface  226  and protruding from base  220 . Consistent with the configuration and proportions of recessed panel portions  86  relative to second planar portion  80 , each raised section  230  is generally narrower and shorter than base  220 , and therefore has a smaller surface area than base  220 . In the embodiment illustrated, each of the upper die sections  160  has multiple raised sections  230 , which are sized and arranged to support the multiple recessed panel portions  86  of second door skin  38  during pressing. Raised sections  230  have a height beyond base  220  corresponding to the depth of recessed panel portions  86  of second door skin  38  inwardly of second planar portion  80 . Each raised section  230  has a panel-supporting contact surface  240  opposite seating surface  226  and facing away from upper platen  120 . 
     Continuing with reference to  FIG. 4 , lower die sections  150  are positioned on lower platen  110  adjacent gaps  138 . Each of the lower die sections  150  includes one or more pegs  198  protruding from bottom surface  176  and arranged to engage with holes  200  or depressions in lower platen  110 , for aligning each of lower die sections  150  on lower platen  110 . Preferably, each of lower die sections  150  has two pegs  198  slidably fitted in two holes  200  when lower die sections  150  are seated against lower platen  110  to inhibit rotation or sliding of each lower die section  150  along the surface of lower platen  110 . Orientation of lower die sections  150  on lower platen  110  using only pegs  198  makes it possible to remove and change out lower die sections  150  without the use of wrenches or other tools. Alternative means for positioning lower die sections  150  on lower platen  110  may also be provided according to a configuration of slots and protrusions or according to other mating or nesting configurations. 
     Lower and upper die sections  150 ,  160 , and particularly the portions thereof that come into contact with door skins  34 ,  38  during pressing, such as contact surfaces  194 ,  240 , are preferably made of a relatively soft, low-friction material, such as white polytetrafluoroethylene (PTFE) or another plastic material or a resilient or elastomeric material such as hard non-marking rubber. The working surfaces of die sections  150 ,  160 , or at least contact surfaces  194 ,  240 , are preferably non-marring by being made of or coated with relatively soft, low friction materials that tend not to scratch or damage door skins  34 ,  38  during pressing. For example, die sections  150 ,  160  may be made of a plastic material having a hardness in the range of about 80 to 110 Shore A or more preferably in the range of about 90 to 105 Shore A; and having a coefficient of static friction against polished steel of less than about 0.4, or less than 0.15, or preferably less than 0.1, or even less than 0.08, measured in accordance with ASTM D1894. Such materials are also desirably light weight, which may facilitate installation and change-over of die sections  150 ,  160  in press  100 . Thus, the system may further include additional sets of one or more replacement die sections removably attachable to platens  110 ,  120  in place of one or more of lower and upper die sections  150 ,  160 , for pressing different sizes or styles of doors. 
     Lower and upper die sections  150 ,  160  are designed and arranged so that when the stack of door components  130  is positioned within press  100  for pressing, each one of the raised sections  182 ,  230  fits within one of recessed panel portions  56 ,  86  of the respective door skins  34 ,  38 . One purpose of raised sections  182  is to reinforce and support the recessed panel portions  56 ,  86  during pressing by press  100 . Reinforcement provided by raised sections  182 ,  230  ensures door skins  34 ,  38  do not fracture or bow outwardly from frame  20  due to outward pressure exerted by core  26  during the pressing operation. Such reinforcement and the attendant crushing of core  26  also ensures that positive adhesive contact is established and thereafter maintained between door skins  34 ,  38  and frame  20 . It is not necessary that contact surfaces  194 ,  240  span the full length or width of recessed panel portions  56 ,  86 . Sufficient reinforcement can be achieved with discontinuous contact surfaces or segmented raised sections having a smaller width, length, and area than the recessed panel portions  56 ,  86 . 
     The bases  170 ,  220  of each of the respective lower and upper die sections  150 ,  160  lie adjacent the stiles and rails regions of door skins  34 ,  38  (i.e. first and second planar portions  50 ,  80 ) during pressing. It is not necessary that the bases  170 ,  220  span any dimension entirely of planar portions  50 ,  80 , but preferably bases  170 ,  220  extend beyond the edges of the planar portions  50 ,  80 . In one embodiment, the height of the raised sections  182 ,  230  are approximately equal to or slightly greater than the depths of the respective recessed panel portions  56 ,  86 . In embodiments wherein raised sections  182 ,  230  have a height above their respective bases  170 ,  220  that is greater than the depth of recessed panel portions  56 ,  86 , the bases  170 ,  220  may not come into contact with first and second planar portions  50 ,  80 . Instead, pressure applied by raised sections  182 ,  230  against panel portions  56 ,  86  may both crush the core  26  and ensure positive adhesive contact between door skins  34 ,  38 , frame  20 , and the adhesive layer applied therebetween. Alternatively, during pressing, the height of raised sections  182 ,  230  being slightly greater than the depth of recessed panel portions  56 ,  86  may cause the door skins  34 ,  38  to bow slightly inward during the pressing process until bases  170 ,  220  come to press against planar portions  50 ,  80  and establish adhesive contact between door skins  34 ,  38  and frame  20 . Inherent resiliency of the door skins  34 ,  38  and core  26  may return the door skins  34 ,  38  to their desired flatness after pressing. 
     During operation, roller conveyor  134  transports the door components  130  into press  100  (wherein roller conveyor  134  is in the raised position indicated by phantom lines in  FIG. 4 ). Roller conveyor  134  pushes door components  130  into contact with positioning guides or stops (not illustrated) within the press to align the door components  130  longitudinally within press  100  and relative to each other. Concurrently, one or more alignment mechanisms  146  may momentarily push against one or more side edges of the door components  130  to establish their lateral alignment within the press  100 . The alignment mechanisms  146  and positioning guides or stops (not shown) are then retracted before the press platens are closed. In another embodiment, the insertion of door components  130  into press  100  is accomplished manually or by some other means than conveyor  134 . In such an embodiment, lower platen  110  may not include channels or gaps  138 , in which case a single lower die section may replace the plurality of lower die sections  150 . Returning to the embodiment illustrated, roller conveyor  134  retracts beneath the upper surface of lower platen  110  (as shown by solid lines in  FIG. 4 ), or at least beneath the upper surface of base  170 , placing the stack of door components  130  onto lower die sections  150 . 
     During the pressing operation, first door skin  34  moves toward frame  20  a distance approximately equal to the depth of recessed panel portions  56 . This motion causes the inner surface  42  of first door skin  34  to be pressed into adhesive contact against the adhesive coating on frame  20 . This motion also causes the recessed panel portions  56  of first door skin  34  to crush (or deform or compress) the portions of core  26  that lie beneath recessed panel portions  56 . 
     After pressing door components  130  to form an assembled door  10 , the press  100  opens by at least one of lower platen  110  and upper platen  120  moving away from the other. The roller conveyor  134  of workpiece transport and positioning subsystem  124 , lifts the pressed assembled door  10  off of lower die sections  150  until door  10  clears lower die  148  so that it can be transported out of press  100  by motorized rollers of roller conveyor  134 . After the pressing operation in press  100 , door  10  may be fed to a separate heated press station (not shown) for curing the adhesive bonds between door skins  34 ,  38  and frame  20 . Alternatively, the press  100  may be heated, eliminating the need for a separate heated press. 
     It will be obvious to those having skill in the art that many changes may be made to the details of the above-described embodiments without departing from the underlying principles of the invention. The scope of the present invention should, therefore, be determined only by the following claims.