Abstract:
A weld wheel assembly for disposition on a membrane welding machine, and for positioning a weld wheel adjacent a nozzle hot air outlet for pressing an overlying roof membrane heated by the nozzle against an underlying roof membrane heated by the nozzle, for welding the membranes together. The assembly includes a weld wheel rotatably mounted on an axle which is moveable toward and away from the membranes, and pressure exerting structure mounted on the machine and operable to bias the axle toward the membranes during operation of the machine.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]    This is a division of application Ser. No. 09/399,129, filed Sep. 20, 1999 in the names of James Rubenacker et al. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The invention relates to a membrane welding machine having a nozzle for directing discrete streams of air along separated and parallel first and second paths, and is directed more particularly to a weld wheel assembly for a machine for heat welding two overlapping roof and/or waterproofing membranes to each other.  
           [0004]    2. Description of the Prior Art  
           [0005]    It is known to provide a device for heat welding two overlapping roof membranes to each other, and to provide such device with a nozzle for directing discrete streams of fluid along separated and parallel first and second weld paths. See, for example, U.S. Pat. No. 4,834,828, issued May 28, 1989, to Colin R. R. Murphy.  
           [0006]    The Murphy patent relates to a machine for effecting continuous heat welds on either side of a fastener means, such as a row of fasteners, or an elongated bar. To effect the parallel welds simultaneously, the Murphy machine is provided with a nozzle which directs a stream of hot air to generally parallel paths on both sides of the fastener means. The upper overlapping membrane is heat sealed to the lower overlapped membrane along the overlap portion to seal the two membranes together on either side of the fastener means. The fastener means fastens the lower membrane to an uppermost hard surface of a roof, and is, in turn, covered by the upper membrane. To effect the two welds simultaneously, the nozzle is essentially a bifurcated nozzle which is moved by the machine between the two membranes, under an edge of the upper membrane.  
           [0007]    The Murphy nozzle is provided with two outlets substantially side-by-side and in substantially the same plane, heightwise. The two outlets are separated by a bridge portion which connects the two outlets and channels hot air thereto. It has been found that the nozzle arrangement is not entirely satisfactory in that the closeness of the two welding locations causes one to adversely influence the other. It has been found that air flows vary in intensity and temperature due to nozzle design. Further, hot air from one nozzle outlet crosses over to the area impacted by the other nozzle outlet and causes bubbling or rippling of the upper membrane on the lower membrane. It has further been found that the two outlets, being in substantially the same plane, both tend to drag along the surface of the lower membrane and cause the nozzle bridge portion, i.e., the nozzle portion between the two outlets, to move along the fastener means with insufficient clearance. Still further, because the Murphy nozzle outlets are in the same vertical plane, and weld simultaneously, the membranes tend to move, causing wrinkles. When the fastener means comprises a row of discrete fasteners or elements, the nozzle bridge portion is bounced upwardly upon encountering a fastener or element, causing the nozzle outlets to rise momentarily, effecting a non-welding segment in both weld paths and potentially creating “fishmouths” in seams. The Murphy nozzle, when inserted into the membrane overlays, is locked into position and cannot accommodate irregularities in the substrate without diminishing seam quality.  
           [0008]    There is thus a need for an improved nozzle of the type described above, but in which the welds are effected concurrently but at points removed from each other such that one weld contributes to another, rather than detracting from the other, and in which the welds are effected continuously and free from interruptions caused by collisions with the fastener means.  
         SUMMARY OF THE INVENTION  
         [0009]    It is, therefore, an object of the invention to provide an improved nozzle for directing discrete streams of hot air along separated and parallel first and second paths.  
           [0010]    A further object of the invention is to provide an improved nozzle for a device for heat welding two overlapping roof membranes to each other, wherein a fastener means is disposed between the overlapping membranes.  
           [0011]    With the above and other objects in view, as will hereinafter appear, a feature of the present invention is the provision of a nozzle for directing discrete streams of fluid along separated and generally parallel first and second paths. The nozzle comprises a chamber for receiving air of a selected temperature, a first outlet arm extending from the chamber and having a first outlet at a distal end thereof and in a first outlet plane, and a second outlet arm extending from the chamber and having a first portion adjoining the chamber and having an axis transverse to an axis of the first outlet arm, and having a second portion with a second outlet at a distal end thereof and in a second outlet plane, an axis of the second portion being generally parallel with the axis of the first outlet arm, the second outlet plane being offset from the first outlet plane.  
           [0012]    In accordance with a further feature of the invention, there is provided a nozzle for a device for heat welding two overlapping roof membranes to each other, wherein a fastener means is disposed between the overlapping roof membranes, and the nozzle is mounted on the device and adapted to effect heat welds to the roof membranes on both sides of, and adjacent to, the fastener means. The nozzle comprises a tubular body defining a chamber for receiving heated air, a first outlet arm extending from the body and having a first outlet at a distal end thereof, a second outlet arm extending from the body and having a first portion adjoining the chamber and having an axis transverse to an axis of the first outlet arm, and having a second portion with a second outlet at a distal end thereof, an axis of the second portion being generally parallel with the axis of the first outlet arm. The second outlet arm first portion is recessed on an underside thereof so as to permit the fastener means to pass therethrough as the device and the nozzle move along the paths.  
           [0013]    In accordance with a further feature of the invention, there is provided a roof membrane welding assembly for heat welding two overlapping roof membranes to each other, wherein a fastener means is disposed between the overlapping roof membranes, the assembly being mounted on a device adapted to effect heat welds to the roof membrane on both sides of, and adjacent to, the fastener means. The welding assembly comprises a nozzle provided with a chamber for receiving heated air, a first outlet arm extending from the chamber and having a first outlet at a distal end thereof, a second outlet arm extending from the chamber and having a second outlet at a distal end thereof, the first outlet being disposed in a first plane, and the second outlet being disposed in a second plane removed from the first outlet plane. A first weld wheel is mounted on the device adjacent to, and in operation immediately following, the nozzle first outlet. A second weld wheel is mounted on the device adjacent to, and in operation immediately following, the nozzle second outlet. One of the weld wheels is biased by biasing structure on the device toward the roof membrane in operation of the device.  
           [0014]    In accordance with a still further feature of the invention there is provided a weld wheel assembly for disposition on a roof membrane welding machine and for positioning a weld wheel adjacent a nozzle hot air outlet for pressing an overlying roof membrane heated by the nozzle against an underlying roof membrane heated by the nozzle, for welding the membranes together. The assembly comprises a weld wheel rotatably mounted on an axle which is moveable toward and away from the membranes, and pressure exerting structure mounted on the device and operable to bias the axle toward the membranes during operation of the machine.  
           [0015]    The above and other features of the invention, including various novel details of construction and combinations of parts, will now be more particularly described with reference to the accompanying drawings and pointed out in the claims. It will be understood that the particular device embodying the invention is shown by way of illustration only and not as a limitation of the invention. The principles and features of this invention may be employed in various and numerous embodiments without departing from the scope of the invention.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]    Reference is made to the accompanying drawings in which is shown an illustrative embodiment of the invention, from which its novel features and advantages will be apparent.  
         [0017]    In the drawings:  
         [0018]    [0018]FIG. 1 is a perspective view of a prior art roof membrane welding machine;  
         [0019]    [0019]FIG. 2 is a perspective view of a prior art nozzle of the type shown on the machine of FIG. 1, and shown in a roof membrane welding operation;  
         [0020]    [0020]FIG. 3 is a partially sectional and partially elevational view of the machine and nozzle of FIGS. 1 and 2 in operation;  
         [0021]    [0021]FIG. 4 is a top planar view of one form of nozzle illustrative of an embodiment of the invention;  
         [0022]    [0022]FIG. 5 is a rear elevational view of the nozzle of FIG. 4;  
         [0023]    [0023]FIGS. 6 and 7 are side elevational views thereof; and  
         [0024]    [0024]FIG. 8 is a bottom view of the nozzle of FIGS.  4 - 7  and a weld wheel assembly in place on a roof membrane welding machine. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0025]    Referring to FIGS.  1 - 3 , it will be seen that a machine  10  on which the invention finds particular utility comprises a frame  12  to which is fixed a handle  14  and on which are mounted wheels  16 , including independent weld wheels  18 . A hot air nozzle  20  is supported on the frame  12  and includes first and second outlets  22 ,  24  for directing two streams of hot air in spaced, generally parallel paths. A housing  26  is mounted on the frame  12  for enclosing a motor and various electrical components and controls (not shown).  
         [0026]    The nozzle  20  is fixed to a heating element  28  which, in turn, is fixed to a blower  30  which is carried by the frame  12 .  
         [0027]    In operation, the nozzle  20  is positioned between roofing membranes A and B (FIGS. 2 and 3) with the nozzle outlets  22 ,  24  on either side of a fastener means F by which the membrane B is secured to a roof uppermost hard surface C. The fastener means F may comprise a batten bar  34 , as shown in FIG. 2, or may comprise a series of discrete stress plates, as is known in the art. The motor in the housing  26  drives the machine  10  in the direction of arrows D. The blower  30  forces air through the heating element  28  and through the nozzle  20 . As the machine moves along, jets of hot air from the nozzle  20  weld the membranes A and B together along opposite sides of the fastener means. Immediately after the hot air welds, the independent weld wheels  18  press the upper membrane against the lower membrane to secure the membranes together. A detailed description of the operation of the machine is provided in the aforementioned &#39;828 patent.  
         [0028]    Referring to FIGS.  4 - 7 , it will be seen that the illustrative nozzle  40  includes a tubular chamber  42  for receiving hot air at a selected temperature. The nozzle  40  further includes a hollow, generally flat, blade-like member  44  at a discharge end  46  of the chamber  42 . The member  44  extends from the discharge end  46  of the chamber  42  generally normal to an axis a-a of the chamber  42 .  
         [0029]    The member  44  includes a first outlet arm  48  extending from the end  46  of the chamber  42 , and having a first outlet  50  at a distal end  52  thereof and disposed in a first outlet plane b-b (FIG. 4). The member  44  further includes a second outlet arm  54  extending from the chamber  12  and having a first portion  56  adjoining the chamber  42 . An axis c-c (FIG. 4) of the first portion  56  extends transversely to an axis d-d of the first outlet arm  48 . The second outlet arm  54  is provided with a second portion  58  with a second outlet  60  at a distal end  62  thereof and in a second outlet plane e-e (FIG. 4). An axis f-f of the second portion  58  is generally parallel with the axis d-d of the first outlet arm  48 . The second outlet plane e-e is offset forwardly of the first outlet plane b-b.  
         [0030]    Referring to FIG. 5, it will be seen that the second outlet arm second portion  58  is further removed from the chamber  42  in a direction of the axis a-a of chamber  42 , than is the first outlet arm  48 . That is, in operation, the second outlet arm second portion  58 , including the second outlet  60 , moves closer to the roof membranes than the first outlet arm  48  and first outlet  50 .  
         [0031]    Referring still to FIG. 5, it will be seen that the first portion  56  of the second outlet arm  54  is provided on an underside  64  thereof with a recess  66  extending from a forward edge  68  (FIG.  4 ) of the second outlet arm first portion  56  to a trailing edge  70  thereof. The recess  66  is a curved concavity with a mid-point  72  (FIG. 5) being most removed from a bottom plane g-g of the second outlet arm second portion  58  and most proximate an upper surface  74  of the second outlet arm first portion  56 .  
         [0032]    As may be seen in FIGS. 4 and 5, the first outlet arm  48  and first outlet  50  are substantially wider side-to-side than the second outlet arm second portion  58  and second outlet  60 .  
         [0033]    Inasmuch as the configurations and dimensions of the nozzle outlets  50 ,  60  are different, an air flow divider  76  (FIG. 4) is provided near the bottom of the chamber  42  in an area of transition to the first outlet arm  48  and the second outlet arm portion  56 . The disposition of the divider  76  provides for substantially equivalent airflow through the respective outlets  50 ,  60 . Substantially equal pre-heating of the membrane surfaces is accomplished by selected sizes and positions of outlet apertures  78  provided in the undersurfaces of the outlet arms  48 ,  54  (FIG. 8), the apertures  78  extending in directions toward the membrane surfaces.  
         [0034]    Referring to FIG. 8, it will be seen that the nozzle  40  is mounted on a machine  80  for heat welding two overlapping roof or waterproofing membranes A, B, as described above, to effect heat welds to the roof membranes on both sides of, and adjacent to, the fastener means F.  
         [0035]    As in the machine  10  of FIGS.  1 - 3 , the nozzle outlets  50 ,  60  are closely followed in operation by weld wheels  82 ,  84 . The nozzle first outlet  50  is followed by a traditional weld wheel  82 . However, because the space available between the nozzle second outlet  60  and an axle  86  for the weld wheel  82  is limited, the nozzle second outlet  60  is followed by a weld wheel  84  of a substantially smaller size than the weld wheel  82 . Further, while a weight  88  (FIG. 8) may easily be added to the weld wheel  82 , similar weights of correspondingly smaller size for the small weld wheel  84  would have little impact on the pressing operation of the weld wheel  84 . Still further, the position of the weld wheel  84  renders the placement of weights on the frame and directed toward the end of pressing the wheel  84  downwardly in use, problematic.  
         [0036]    To provide the desired downwardly directed force on the weld wheel  84 , the wheel  84  is mounted on a spring-biased lever  90  which biases the wheel  84  toward the welded seam with a force substantially equal to the force applied by the weld wheel  82 .  
         [0037]    In operation, the machine  80  is positioned relative to roof membranes A and B substantially as shown in FIGS. 2 and 3 with respect to machine  10 . The heating element  28  and blower  30  are started by means well known in the art, as are other known controls, sensors, and the like. The machine  80  is moved along the roof membranes with the nozzle  40  discharging two discrete streams of hot air, one from the outlet  50  and the other from outlet  60 . The two outlets  50 ,  60  effect seals simultaneously in the sense that both eject hot air at the same time. However, the nozzle outlets  50 ,  60  effect seals at any given time along their respective paths at points removed from each other, that is, in a staggered manner.  
         [0038]    Referring to FIG. 8, it will be seen that as the machine  80  advances in the direction D, the nozzle outlet  60  proceeds in advance of the nozzle outlet  50 . The weld wheel  84  follows immediately behind nozzle outlet  60 . Thus, the first weld (effected by outlet  60 ) is accomplished well removed from the second weld (effected by outlet  50 ), and the first weld and the pressure application thereto by weld wheel  84  is accomplished without interference from the second weld hot air flow, resulting in better consistency and quality in the first weld. Further, inasmuch as the first weld is pressure closed ahead of the second weld, the first weld traps the hot air flowed in performance of the second weld in the vicinity of the second weld, such that hot air is retained in the second weld area, improving second weld consistency and quality.  
         [0039]    Referring to FIG. 5, it will be seen that the second outlet  60  is further removed from the chamber  42  than the first outlet  50 , in a direction of the lengthwise axis a-a of the chamber  42 . That is, in operation, the second outlet  60  is lower, or closer to the membrane B, than the first outlet  50 , and the first outlet  50  is higher, or further from the membrane B than the second outlet  60 . Keeping in mind that the second outlet  60  moves ahead of the first outlet  50  in operation, hot air from the leading and lower second outlet  60  is able to move transversely toward an area beneath the following and slightly raised first outlet  50  to make a contribution to the weld of the first outlet  50 . Further, the slightly raised position of the first outlet  50  insures that the first outlet remains elevated relative to the second outlet  60  and is positioned above the lower membrane even when the second outlet drags along the surface of the lower membrane B. During the course of the welding operation, the nozzle recess  66  always moves over the fastener means F, leading to uninterrupted welds of high quality and consistency.  
         [0040]    There is thus provided an improved nozzle for directing discrete streams of hot air along first and second paths concurrently. There is further provided such a nozzle for heat sealing two overlapping roof membranes to each other, wherein a fastener means is disposed between the overlapping membranes. There is additionally provided a unique weld wheel arrangement which permits use of the above-described nozzle in a roof membrane welding machine.  
         [0041]    It is to be understood that the present invention is by no means limited to the particular construction herein disclosed and/or shown in the drawings, but also comprises any modifications or equivalents within the scope of the claims.