Abstract:
A dual roll fabric welding or seaming machine is configured to seam pieces of sheet material to one another as the pieces move downstream. The machine includes modular gantries and various actor devices which may be readily mounted on any of the gantries to interact with the moving sheet material to achieve various functions, such as seaming pieces of sheet material together, forming hems, applying grommets to the sheet material, printing on the sheet material, connecting reinforcement strips or ropes to the sheet material and cutting the sheet material.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 14/073,212, filed Nov. 6, 2013, which claims priority from U.S. Provisional Patent Application Ser. No. 61/723,073, filed Nov. 6, 2012; the disclosures of which are incorporated herein by reference. 
    
    
     BACKGROUND 
     1. Technical Field 
     The technical field relates generally to seaming machines. More particularly, the technical field relates to a seaming machine or fabric welding machine and method of seaming two or more sheet segments together and performing other functions to manipulate the seamed sheet of material. Specifically, the technical field relates to a dual roll fabric welding machine with a modular configuration. 
     2. Background Information 
     Dual roll fabric welding machines are well known in the art. Typically, first and second rolls of sheet material are controlled to unwind and move downstream through the machine so that the two sheets of unwound material are seamed or welded together to form a single wider sheet. The machine then performs other functions to further manipulate or alter the seamed sheet material. One problem with such machines is the difficulty in setting them up for operation especially when there is a requirement to meet one specification and then reconfiguring the machine to meet a different specification. 
     SUMMARY 
     In one aspect, a method may comprise the steps of moving sheet material downstream past a first gantry and a second gantry; performing a function which affects the sheet material with a first actor device mounted on the first gantry as the sheet material is moving downstream; performing a function which affects the sheet material with a second actor device mounted on the second gantry as the sheet material is moving downstream; wherein the first actor device is removable from the first gantry and mountable on the second gantry; and the second actor device is removable from the second gantry and mountable on the first gantry. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       A sample embodiment is set forth in the following description and is shown in the drawings and is particular and distinctly pointed out and set forth in the appended claims. 
         FIG. 1  is a side elevational view of a seaming machine. 
         FIG. 2  is a top plan view of the seaming machine. 
         FIG. 3  is a front elevational view of one of the gantries. 
     
    
    
     Similar numbers refer to similar parts throughout the drawings. 
     DETAILED DESCRIPTION 
     A seaming or fabric welding machine is shown generally at  1  in  FIGS. 1 and 2 . In the exemplary embodiment, machine  1  is shown as a plastic welding machine in which plastic welders are used to form seams between various segments of sheet material. However, machine  1  also represents various other types of seaming machines, such as ultrasonic welding machines, radio frequency (RF) welding machines, adhesive seaming machines, gluing seaming machines and sewing machines. Machine  1  is used to seam together various segments of sheet material to form larger sheets of material, such as tarpaulins for covering trailers and the like, tents, awnings, canopies, banners, and various other items. 
     As shown in  FIGS. 1 and 2 , machine  1  has first and second ends  2  and  4  defining therebetween a longitudinal direction and first and second sides  6  and  8  defining therebetween an axial direction. First end  2  is an upstream end and second end  4  is a downstream end whereby during operation of machine  1  sheet material moves downstream in the longitudinal direction from upstream end  2  to downstream end  4 . Machine  1  is configured to weld segments of sheet material together along respective typically parallel longitudinal edges thereof to form a welded sheet of material having a length which is increased in the axial direction and typically about (and a little less than) twice as wide as the two sheets from which it is formed although this may vary. 
     Machine  1  includes a rigid frame base  10  on which several components are securely mounted. In the exemplary embodiment, base  10  includes longitudinally elongated parallel left and right rails  12  and  14 , each of which includes an upstream section  13  and a downstream section  15 . Downstream section  15  defines a longitudinally elongated U-shaped channel  17  which opens upwardly and extends from adjacent the upstream end of section  15  to adjacent the downstream end of section  15 . Machine  1  further includes a left sheet material unwinding assembly  16  and a right sheet material unwinding assembly  18 . Left assembly  16  is adjacent, to the left of and downstream of right assembly  18 . Machine  1  also includes several gantries  20 . In the exemplary embodiment, there are four gantries  20 A- 20 D all of which are downstream of unwinding assemblies  16  and  18  and which are sequentially downstream of one another. Gantries  20  are longitudinally spaced from one another and secured to rails  12  and  14 . Gantries  20  are identical or essentially identical and are aligned so as to appear superimposed on one another as viewed in the longitudinal direction. Machine  1  further includes upstream and downstream catwalks  22 A-B each extending between and mounted on upstream sections  13  of rails  12  and  14 . Catwalk  22 A is downstream of unwinding assemblies  16  and  18  and upstream of all of gantries  20  and catwalk  22 B. Downstream catwalk  22 B is downstream of gantries  20 A and  20 B and upstream of gantries  20 C and  20 D. 
     Each unwinding assembly  16 ,  18  includes a rigid frame  24  with an electronic control box  26  mounted thereon. Each unwinding assembly also includes a horizontal roller  28 A and is configured for removably mounting thereon a spool  30  configured to support a roll  32  of sheet material  34  to be unwound from roll  32 . Each of roller  28 A and spool  30  is axially elongated and rotatable about an axis extending in the axial direction so that roller  28 A, spool  30  and each axis is perpendicular to the longitudinal direction and, during operation, perpendicular to movement of unwound sheet material  34  in the downstream direction. Roller  28 A and spool  30  are thus parallel to one another. Unwinding assemblies  16  and  18  axially overlap one another partially as viewed in the longitudinal direction. More particularly, each of left and right unwinding assemblies  16  and  18  has left and right sides, and are positioned so that the left side of right unwinding assembly  18  is to the left of the right side of left unwinding assembly  16  and to the right of the left side of unwinding assembly. The left side of right unwinding assembly  18  is axially offset and adjacent the right side of left unwinding assembly  16  whereby the left edge of sheet material  34  unwinding from right unwinding assembly  18  overlaps and is adjacent the right edge of sheet material  34  unwinding from left unwinding assembly  16 . The left side of right unwinding assembly  18  is axially offset and distal the left side of left unwinding assembly  16 . 
     Each catwalk  22  includes a horizontal axially elongated walkway  36  having an upstream side and a downstream side, a vertical upstream fence  38 A extending upwardly from adjacent the upstream side and a vertical downstream fence  38 B extending upwardly from adjacent the downstream side. Fences  38 A and  38 B are axially elongated and longitudinally spaced from one another. Each walkway  36  and fence  38  extends from adjacent left side  6  and left rail  12  to adjacent right side  8  and right rail  14 . Each walkway  36  includes a central portion which extends from adjacent rail  12  to adjacent rail  14  and is slightly elevated so that the bottom of each central portion is spaced upwardly from the floor on which machine  1  is seated whereby the floor and bottom of each central portion define therebetween an open space  33  to allow sheet material  34  to move therethrough during operation, as discussed further below. Each fence may also be called a guardrail which serves to protect a person from falling off of the walkway and thus helps to prevent injury which might otherwise occur. Each fence  38  typically includes at least a pair of rigid uprights on either end and several rigid horizontal bars extending from adjacent the left end of the fence to adjacent the right end of the fence and secured to the uprights. Rigid roller supports  40 A and  40 B are provided respectively upstream of and adjacent the fence  38 A of upstream catwalk  22 A and downstream of and adjacent fence  38 B of upstream catwalk  22 A. Rigid roller supports  40 C and  40 D are likewise provided respectively upstream of and adjacent the fence  38 A of downstream catwalk  22 B and downstream of and adjacent fence  38 B of downstream catwalk  22 B. The roller supports  40  associated with each catwalk  22  may be secured to the catwalk or separate therefrom. In either case, supports  40  are typically secured directly or indirectly to upstream sections  13  of rails  12  and  14 . 
     Machine  1  further includes multiple horizontal rollers  28 B-M in addition to rollers  28 A. All rollers  28  are axially elongated, parallel to one another and rotatable about respective horizontal parallel axes which extend in the axial direction. Roller  28 B is rotatably mounted on roller support  40 A adjacent an upper end thereof and roller  28 C is rotatably mounted on roller support  40 A adjacent a lower end thereof. Roller  28 E is rotatably mounted on roller support  40 B adjacent an upper end thereof and roller  28 D is rotatably mounted on roller support  40 B adjacent a lower end thereof. Roller  28 H is rotatably mounted on roller support  40 C adjacent an upper end thereof and roller  28 I is rotatably mounted on roller support  40 C adjacent a lower end thereof. Roller  28 K is rotatably mounted on roller support  40 D adjacent an upper end thereof and roller  28 J is rotatably mounted on roller support  40 D adjacent a lower end thereof. Rollers  28 F,  28 G,  28 L and  28 M are respectively rotatably mounted on gantries  20 A,  20 B,  20 C and  20 D. 
     In the exemplary embodiment, the tops of the upper set of rollers  28 B,  28 E,  28 F,  28 G,  28 H,  28 K,  28 L and  28 M are at about the same height as one another while the bottoms of the lower set of rollers  28 C,  28 D,  28 I and  28 J are likewise at about the same height as one another. The rollers  28  in the lower set are generally adjacent base  10  and the lower end of machine  1  and substantially lower than the rollers of the upper set. The bottoms of the rollers  28 C and  28 D are lower than the bottom of the central portion of walkway  36  of upstream catwalk  22 A. Likewise, the bottoms of the rollers  28 I and  28 J are lower than the bottom of the central portion of walkway  36  of downstream catwalk  22 B. Space  33  below upstream catwalk  22 A extends from adjacent the bottom of roller  28 C to adjacent the bottom of roller  28 D. Likewise, space  33  below downstream catwalk  22 B extends from adjacent the bottom of roller  28 I to adjacent the bottom of roller  28 J. 
     As noted above, gantries  20  are identical or nearly identical and thus are formed as modular units which can be used in place of one another, that is, they are typically interchangeable. Gantry  20  of  FIG. 3  is thus representative of each of gantries  20 A- 20 D although there may be some relatively minor variations. Primarily, any such variation is typically related to the configuration of gantries  20 A and  20 B relative to the configuration of gantries  20 C and  20 D. More particularly, gantries  20 A and  20 B are typically stationary gantries and thus fixedly secured to sections  13  of rails  12  and  14 , whereas gantries  20 C and  20 D are typically longitudinally movable gantries (Arrows A, B in  FIG. 1 ) and thus movably mounted on sections  15  of rails  12  and  14 . Thus, gantries  20 C and  20 D typically include rail-engaging or track-engaging wheels  42  whereby the left wheels  42  rollingly engage section  15  of left rail  12  and the right wheels  42  rollingly engage section  15  of right rail  14 . Wheels  42 , which may be within channels  17  respectively, may be drive wheels configured to drive longitudinal movement of gantries  20 C and  20 D upstream and downstream along sections  15 , or may be non-driven wheels such that an actuator may push or pull gantries  20 C and  20 D upstream and downstream. Gantries  20 A and  20 B may be formed without wheels  42 . However, gantries  20 A and  20 B may also be formed such that wheels  42  can be readily mounted thereon. Likewise, gantries  20 C and  20 D may be formed such that wheels  42  are readily removable. Furthermore, all of the gantries may be formed with wheels, and gantries  20 A and  20 B can simply be positioned for stationary use, such as by locking the wheels or placing them on a portion of base  10  in a manner that will prevent them from rolling. 
     With primary reference to  FIG. 3 , gantry  20  is described in greater detail. Gantry  20  comprises a rigid frame which includes a rigid lower axial beam  44 , a rigid upper axial beam  46 , and rigid left and right uprights  48  and  50 . The left end of lower beam  44  is rigidly secured to the lower end of left upright  48 , and the left end of upper beam  46  is rigidly secured to the upper end of left upright  48 . The right end of lower beam  44  is rigidly secured to the lower end of right upright  50 , and the right end of upper beam  46  is rigidly secured to the upper end of right upright  50 . Beams  44  and  46  and uprights  48  and  50  together form a rectangular structure and define therebetween a sheet material-receiving through passage  52  which extends from the upstream end of gantry  20  to the downstream end of gantry  20  and through which sheet material  34  passes during operation. Passage  52  thus has an entrance opening  54  ( FIG. 1 ) along the upstream end of gantry  20  and an exit opening  56  along the downstream end of gantry  20 . Gantry  20  has left and right feet  58  secured to and extending downwardly from bottom of the main rectangular structure respectively along the left and right sides thereof. A control box  60  is mounted on the left side of the rectangular structure of gantry  20  and is typically in the form of a programmable logic controller (PLC). A mounting rail  62  extends along the bottom of upper beam  46  from adjacent left upright  48  to adjacent right upright  50 . An axially elongated horizontal work platform  64  is provided within passage  52  directly in front of or upstream of and parallel to roller  28  of gantry  20 . Platform  64  is spaced upwardly of and rigidly secured to lower beam  44  by a plurality of support poles  66 . One or more actuators or motors  68  are typically mounted on gantry  20  and in electrical or other communication with control box  60  so that box  60  may be programmed to specifically control actuators or motors  68 . 
     Gantries are configured to respectively support actor devices  70 A- 70 D. Devices  70  are mountable on any of mounting rails  62 . Thus, mounting rails  62  are configured as universal mounting structures with respect to devices  70  so that any of devices  70  may be readily mounted on any given rail  62 . Each device  70  shown may be in the form of a single unit or may include several units or actor devices which perform different functions. More particularly, each actor device  70  is configured to interact with sheet material  34  during downstream movement of sheet material  34  though machine  1 . Each device  70  is configured to perform a function or operation which directly affects sheet material  34  during the downstream movement of material  34 . Each actor device thus includes a component that engages sheet material  34  or applies or connects a workpiece component to sheet material  34 , which itself is a workpiece component, to ultimately produce a finished product or workpiece. Each control box  60  is typically programmed to control the actor device or devices on the corresponding gantry  20  to provide a specified predetermined configuration of the final workpiece formed from the pieces of sheet material  34  which is unwound from rolls  32  and any other components added thereto as discussed below. 
     Each actor device  70  may, for example, be or include a welding device or other seaming device capable of seaming or welding a portion of sheet material  34  to itself or another piece of sheet material  34 ; a folding device positioned to fold over a portion of sheet material  34 ; a keder device or rope positioning device configured to position a rope within a folded loop or channel of sheet material  34  to be seamed to form a rope passage so that the rope extends through the rope passage and is thus connected to the sheet material; a grommeting device or grommet applicator which applies or secures grommets or eyelets to the sheet material; a print head which prints various indicia on sheet material  34 , such as logos or other alphabetical and/or numerical characters and/or designs or graphics; a cross cutting device which cuts sheet material in the axial direction typically perpendicular to the downstream movement of sheet material  34  through machine  1 . 
     The above-noted seaming or welding device mentioned in the previous paragraph may be, for example, an overlap welding or other seaming device for welding or otherwise seaming two pieces of sheet material together along respective parallel longitudinal edges of the two pieces. The above-noted seaming or welding device may also, for example, be a part of a hem former which forms a hem along an edge of sheet material  34  by folding over with a folding device a first section of sheet material  34  onto an adjacent second section of sheet material  34  and welding or otherwise seaming the first and second sections to one another. The above-noted seaming or welding device may also be, for example, a cross welder or cross seamer which welds or otherwise seams an additional strip of sheet material (typically a reinforcement strip) onto sheet material  34  so that the additional strip secured to sheet material  34  is axially elongated, typically perpendicular to the downstream movement of sheet material  34  through machine  1 . The examples of actor devices  70  given above is not exhaustive and may include other such devices known in the art. The welding device typically includes a heated welding tip which is positionable adjacent sheet material  34  and a pair of pinch rollers which are adjacent and downstream of the welding tip and configured to press therebetween the sheet material heated by the welding tip to complete the welded seam. 
     Although the various types of actor devices  70  may be mounted on any given gantry  20 , machine  1  in the exemplary embodiment it typically configured as follows. Device  70 A typically comprises an overlap seaming device for seaming two pieces of sheet material together, one or more hem formers which include a folding device and a seaming device, and may also include a keder device or rope positioning device as discussed above. Device  70 B typically includes a grommeting device or grommet applicator and a print head. Device  70 C typically includes a cross welder or cross seamer for securing a reinforcement strip to sheet material  34 . Device  70 D typically includes a cross cutting device. 
     The operation of machine  1  is now described given the configuration provided in the previous paragraph. Rolls  32  of sheet material  34  are mounted on spools  30  and positioned so that material  34  may be unwound from rolls  32 . Control boxes  26  and  60  are programmed to control the various operations performed by machine  1  and thus are in electrical or other communication with the various actuators, motors, brakes, various electrical circuitry and other components necessary to control these operations. More particularly, boxes  26  are programmed to properly control the unwinding of sheet material  34  from the respective rolls  32 . Each piece of sheet material  34  moves downstream from its respective roll  32  to and beyond the downstream end  4  of machine  1 . Each piece of sheet material  34  engages each of rollers  28  as it moves downstream. More particularly, each piece of sheet material  34  goes over its respective roller  28 A and over rollers  28 B,  28 E,  28 F,  28 G,  28 H,  28 K,  28 L and  28 M and goes under rollers  28 C,  28 D,  28 I and  28 J. Thus, each piece of sheet material  34  extends generally horizontally from its roller  28 A to roller  28 B, substantially vertically downward from roller  28 B to roller  28 C upstream of and adjacent fence  38 A of catwalk  22 A, substantially horizontally from roller  28 C to roller  28 D under walkway  36  of catwalk  22 A within upstream space  33 , substantially vertically upward from roller  28 D to roller  28 E downstream of and adjacent fence  38 B of catwalk  22 A, substantially horizontally from roller  28 E to roller  28 F to roller  28 G to roller  28 H and through passages  52  of gantries  28 A and  28 B, substantially vertically downward from roller  28 H to roller  28 I upstream of and adjacent fence  38 A of catwalk  22 B, substantially horizontally from roller  28 I to roller  28 J under walkway  36  of catwalk  22 B within downstream space  33 , substantially vertically upward from roller  28 J to roller  28 K downstream of and adjacent fence  38 B of catwalk  22 B, and substantially horizontally from roller  28 K to roller  28 L to roller  28 M and through passages  52  of gantries  28 C and  28 D. 
     Sheet material  34  from left roll  32  has parallel longitudinal left and right edges  72  and  74 . Sheet material  34  from right roll  32  has parallel longitudinal left and right edges  76  and  78  which are parallel to edges  72  and  74 . Left edge  72  of the left piece of sheet material  34  is adjacent the left ends of rollers  28 B- 28 M and generally adjacent left side  6 . Right edge  78  of the right piece of sheet material  34  is adjacent the right ends of rollers  28 B- 28 M and generally adjacent right side  8 . Left edge  76  of the right piece of sheet material  34  partially axially overlaps and is adjacent right edge  74  of the left piece of sheet material  34  and distal left edge  72  of the left piece. 
     As the left and right pieces of sheet material  34  move downstream, the various actor devices  70  interact with these pieces. The overlap welding or seaming device of actor device  70 A welds or otherwise seams left and right pieces of sheet material  34  together along edges  74  and  76  to form a longitudinally elongated overlap seam parallel to edges  72 - 76  and to the direction of movement of material  34  through machine  1 . Actor device  70 A typically includes a hem former which forms a hem along one of left edge  72  of the left piece of sheet material  34  and right edge  76  of the right piece of sheet material  34 . Actor device  70 A may also have another hem former which forms a hem along the other of left edge  72  and right edge  76 . When desired, actor device  70 A may also include one or more keder or rope positioning devices to position a rope within the folded loop or channel formed by the one or more folding devices of device  70 A along edges  72  and/or  76 , whereby the seaming device of the hem former seams the sheet material  34  to form a rope passage along edges  72  and/or  76  so that the rope extends through the rope passage and is thus connected to the sheet material. 
     After the overlap seaming device has interacted with the left and right pieces of sheet material to form the overlap seam therebetween, the two pieces are seamed together to form a single joined piece of sheet material  34  extending from adjacent the left ends of rollers  28 F-M to adjacent the right ends of rollers  28 F-M. The grommeting device or grommet applicator of actor device  70 B secures grommets or eyelets to the joined piece of sheet material  34  in accordance with the program of control box  60  of gantry  20 B. The print head of actor device  70 B prints the desired indicia on the joined piece of sheet material  34  in accordance with the program of control box  60  of gantry  20 B. The cross welder or seamer of actor device  70 C moves axially (Arrow C in  FIG. 2 ) across the joined sheet material  34  to weld or otherwise seam a reinforcement strip of sheet material onto sheet material  34  as described above in accordance with the program of control box  60  of gantry  20 C. This step occurs as gantry  20 C moves downstream (Arrow A in  FIG. 1 ) at the same downstream rate as sheet material  34  under control of the program of control box  60  of gantry  20 C. Control box  60  of gantry  20 C then controls gantry  20 C to move back upstream to its home position. The cross cutting device of actor device  70 D moves axially (Arrow D in  FIG. 2 ) across the joined sheet material  34  to cut the joined pieces of sheet material  34  in the axial direction as described above in accordance with the program of control box  60  of gantry  20 D. This step occurs as gantry  20 D moves downstream (Arrow B) at the same downstream rate as sheet material  34  under control of the program of control box  60  of gantry  20 D. Control box  60  of gantry  20 D then controls gantry  20 D to move back upstream to its home position. 
     After the joined sheet material  34  has been cut by the cutting device of actor device  70 D, the separated piece is a finished workpiece. In the exemplary embodiment of machine  1 , all operations of machine  1  occur while sheet material is moving downstream, thus providing an automated continuous, non-stop operation absent normal machine shutdown or shutdown for repair or adjustments. When the user desires to change the configuration of machine  1  to meet an alternate product specification, doing so is relatively simple due to the ease with which the actor devices may be removed from one gantry and/or mounted on a different gantry. Furthermore, if additional gantries are needed to provide additional functions performed by the actor devices, it is a relatively simple matter to add such gantries due to their modular configuration. 
     In the foregoing description, certain terms have been used for brevity, clearness, and understanding. No unnecessary limitations are to be implied therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes and are intended to be broadly construed. Moreover, the description and illustration is an example and is not limited to the exact details shown or described.