Abstract:
A method and apparatus for automatically cutting notches at specific locations on a web which are separated by predetermined lengths which are the outer dimensions of a pillowtop mattress. The web is pulled through a sewing station with a traction drive. Slack is induced in the web downstream of the traction drive. Predetermined lengths are drawn out of the slack bin in a single motion through a linear measuring device. A knife disposed in close proximity to the measuring device cuts the notches at the specific locations and subsequently severs the notched portion from the remainder of the web.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a gusset manufacturing machine for producing pillowtop mattresses. More particularly, it relates to such a machine having an automatic measuring and cutting station for the corner notches. 
     2. Prior Art 
     Recently, the mattress industry has adopted pillowtop mattresses as the standard in their premium mattress lines. The pillowtop is essentially a cushioned pad attached to the upper surface of the mattress. To enhance the comfort and aesthetics of this design, the periphery of the pillowtop remains free from the edge of the mattress. Rather, the periphery of the pillowtop is secured to the upper flap of an inwardly-folded gusset. The lower flap of the gusset includes a flange, both of which are secured to the edge of the mattress. The flange extends inwardly past the gusset fold where it is secured to the mattress&#39; spring unit. 
     Gusset construction consists of doubling-over and stitching the gusset material to create the fold line and sewing the flange material to the bottom flap of the gusset. To simplify this operation, certain prior art methods attach the flange material at the gusset fold line in a single operation. Ideally, the flange material is secured to the free end of the lower gusset flap. In either case, the material handling necessary for the folding, unfolding and joining operations, require the gusset and flange to be unspooled and sewn together in a continuous web. In a subsequent manual operation, needing a large workspace, the web is laid out and alternating length and width measurements are made along its length. At the end of each measured length, notches are cut into the web or cut as the gusset is being taped to the top panel. The edges of each notch are sewn together to form a corner. It would, therefore, be desirable to automatically measure and notch the web in a mechanized operation immediately following creation of the continuous web. 
     SUMMARY OF THE INVENTION 
     It is a primary object of the present invention to provide a measuring and cutting station in-line with the gusset and flange sewing operations. 
     It is a further object of the invention to continuously cut notches into the web and to severe completed gusset frames from the web. 
     It is another object of the invention to provide slack-induced sections of the web to the measuring and cutting station so that the web may be drawn and accurately measured without tension. 
     It is yet another object of the invention to provide a slack bin that is automatically filled by the upstream sewing stations. 
     These and other related objects are achieved according to the invention by a method and apparatus for automatically cutting notches at specific location on the web which are separated by predetermined lengths which define the outer dimensions of a pillowtop mattress. The web is pulled through a sewing station with a traction drive. Slack is induced in the web by downstream of the traction drive. One predetermined length is drawn out of the slack bin in a single motion through a linear measuring device. A knife disposed in close proximity to the measuring device cuts the notches at the specific locations. After all four predetermined lengths are measured and notched, the knife separates the notched section from the remainder of the continuous web. 
     In the first stage sewing operation, a first material is folded and a first seam is sewed along the folded edge. A second material is sewn to the first material along one of the free ends. The first and second sewing steps and the associated traction drive are synchronized to pull the web uniformly. After the sewing operation, the web is suspended to form a slack loop under the influence of gravity. A sensor within the slack bin generates a sensor output representative of the length of a slack loop. The output is evaluated to determine when additional slack needs to be generated. The traction drive is selectively operated within a feedback loop to control operation of the upstream sewing station. 
     Material from the slack bin is pulled without tension to measure a particular predetermined length. A cutting device positioned in close proximity to the linear measuring device cuts a notch into one side of the web. The notch may be formed with one V-shaped die cut or two knife cuts oriented at 90 degrees from each other. After one entire pillowtop gusset is notched, the same or a different knife severs the gusset from the remainder of the continuous web with a cut oriented approximately 90 degrees to the longitudinal direction of the web. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the accompanying drawings to which reference is made in the instance specification and which are to be read in conjunction therewith and which like reference characters are used to indicate like parts in the various views: 
     FIG. 1 is a schematic view of an embodiment of a gusset-forming machine according to the invention. 
     FIG. 2A is a top plan view of the measuring and cutting station. 
     FIG. 2B is a top plan view of an alternate embodiment of the measuring and cutting station. 
     FIG. 3 is a flow chart outlining the operational steps of the gusset-forming machine. 
     FIG. 4 is a flow chart outlining the operational steps of the measuring and cutting station. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now in detail to the Figures, and in particular FIG. 1 there is shown an embodiment of the gusset-forming machine according to the invention. To summarize, gusset material  10   a  and flange material  20   a  are subject to several sewing operations which result in the creation of a continuous folded gusset having flange secured to the lower flap thereof. The formed gusset with flange drops into a slack bin from which it can be drawn by the measuring and cutting station without tension. Before describing the gusset-forming machine in greater detail, an operational overview of the process will be provided by reference to FIG.  3 . Please note that reference numerals from FIG. 1, for example, spool  10 , have a corresponding operational step in FIG. 3, by incrementing the reference numeral by 100, i.e., step  110 -Unspool material from the roll. 
     As can be seen in FIG. 3 the first step  110  consists of unspooling border material from its roll. The border material is folded in step  112 . For example, the border material may be folded in half along its length thereby defining a pair of overlying, longitudinally-extending free edges and a spaced opposite, longitudinally-extending folded edge. In step  114  an overlock seam is sewn onto the folded edge. The border material is unfolded in step  118  and joined with flange material  120  as they enter an alignment and tension guide  122 . The flange material is sewn onto the free edge of the lower flap of the border material with an overlock stitch in step  124 . The joined materials then enter a slack bin where it is measured to maintain adequate slack in step  130 . Material is drawn, without tension, from the slack bin, where it is measured and notched in step  150 . If inadequate slack is sensed in step  130 , the upstream sewing machines are activated in step  136 . In order to maintain the alignment and tension during the sewing operations, the sewing steps  114  and  124  are operated in tandem by motor/sync controller in step  138 . 
     The measuring and cutting step  150  is described in greater detail in FIG.  4 . Initially the desired length and width of the pillowtop are set in step  152 . The material drive is activated to draw the web out of the slack bin and the width is measured in step  154 W. A notch is cut into the web at knife positions A and B in step  156 AB. Parenthetically, if additional slack is required, steps  136  and  138  from FIG. 3 would be carried out independently of the measuring and cutting steps. The material drive is again activated and the length is measured out along the web in step  154 L. A notch is cut into the web at knife positions A and B in step  156 AB. To measure and cut the subsequent width and length sections, steps  154 W and  156 AB and  154 L and  156 AB are repeated once. Having measured all four sections of the gusset frame, the web material is cut completely through at knife position C in step  156 C. 
     Referring now to the equipment of FIG. 1, roll  10  is mounted so that border material  10   a  spools off roll  10 . Material web  10   a  enters a folding device  12  wherein the longitudinally-extending free ends of the material would meet, facing out of the page. The longitudinally-extended folded edge resulting therefrom would face into the page. Roll  10  is mounted so that the material feeds easily into folding device  12  without wrinkling or creasing, for example the material may spool off in a horizontal or near horizontal direction. A sewing machine  14   a  of first sewing station  14  sews an overlock seam at, or adjacent to, the longitudinally-extending folded edge. As material  10   a  exits first sewing station  14  at location  18 , the upper flap is unfolded 180 degrees clockwise, as viewed along the direction web advancement. 
     An alignment and tensioning guide  22  includes a lower slot for receiving flange material  20   a  from a flange spool  20 . The upper slot in guide  22  receives the unfolded border material. The far edges of the flange and border material, i.e., the edges extending into the page, are carefully aligned. The edges are also held under tension between drive wheel  24   b  and guide  22  to keep them flat and smooth. The flange and border material are sewn together at their aligned edges with an overlock stitch by a sewing machine  24   a  of second sewing station  24 . The feed mechanism of sewing machine  24  is assisted by a positive drive wheel  24   b.    
     The joined material falls under the influence of gravity into a slack bin  32  which includes roll guides  32   a  and  32   b.  A single sensing device or sensor block  34  is disposed vertically within slack bin  32 . The output from sensor block  34  is identified as slack level sensor array  30 . Array  30  provides an input to process controller  36  based on the slack level and rate of slack production and reduction. Process controller  36  provides control signals to a motor/sync controller  38  that provide synchronized operation of sewing stations  14  and  24  including uniform material advancement via the traction feeds of sewing machines  14   a  and  24   a  as well as traction wheel  24   b.  Second sewing station  24  may include internal synchronization of sewing machine  24   a  and traction wheel  24   b.  The synchronization of sewing machines  14   a  and  24   a  may be accomplished by the device specified in U.S. Pat. No. 3,990,374, entitled Contactless Synchronizer for Sewing Machines, the contents of which are incorporated herein by reference thereto. 
     As an example, assume that the slack within bin  32  should normally extend down to sensor  34   c.  If measuring and cutting station  50  draws material for a short section, the web is drawn out of the slack bin across sensor  34   b  whereby the slack level sensor array  30  signals process controller  36  to activate the sewing stations to provide more slack until the loop extends down passed sensors  34   b  and  34   c.  Alternatively, if measuring and cutting station  50  draws a large amount of slack, for example, for an extended length, the slack loop passes upwardly passed sensors  34   b  and  34   a.  In this instance, process controller  36  may perform an extended or faster synchronized sewing operation. 
     The operation of measuring and cutting station  50  may be seen in greater detail with reference to FIG.  2 A. Material drive and measurer  54  rotates an axle  54   a  which carries a traction drive  54   b  that draws material without tension from the slack bin through a guide  53   a  where the lower flap is folded 180 degrees clockwise, as viewed along the direction of web advancement. All measuring and cutting operations are based on the length and width of the mattress or pillowtop to be manufactured. These dimensions are fed to the process controller  36  via block  52 . Once the width dimension is measured, the knife positioning and actuating device  56  cuts at position  56 A. The knife then swings along arc  58  to position  56 B to complete the first notch. The material drive and measurer  54  then draws a length section of web and additional cuts are made at positions  56 A and  56 B forming the second notch. After another width dimension is drawn and notched, the material drive and measurer  54  draws material for the final length dimension. FIG. 2A illustrates the configuration at this point. At the final corner after the notch is cut, the knife is oriented perpendicular to the web and indexed forward to position  56 C to sever the notched portions from the web. 
     As can be seen in FIG. 2A adjacent length and width portions are rotated 90 degrees toward each other to form a structure resembling a picture frame. The edges denoted as  156 A are joined to the facing edges  156 B in a subsequent sewing operation, leaving a frame whose outer perimeter is closely matched to the outer perimeter of the mattress. The flange material  20   a  extends into the center of the frame and may be attached to an inner panel which applies tension like a trampoline, to all four inside edges of the border material. This draws the inside, folded edge of the border material inwardly to eliminate any wrinkles or pleats in the material along the perimeter of the frame. This frame can be attached to the underside of a quilted mattress panel using a blind stitch machine, by sewing an inner perimeter of the frame to the foam underside of the panel. 
     FIG. 2B shows an alternate embodiment for notching the border material  10   a  only and leaving the flange material  20   a  unnotched. Guide  53   b  is extended in the direction perpendicular to the longitudinal direction of the web to spread flange  20   a  away from border  10   a.  The notch is cut into border  10   a  only, for example, with a single die cut along the V-shaped line  56 N. To sever the notched portions from the remainder of the web, the severing cut line  56 C must now extend twice as far to cut across both materials  10   a  and  20   a.  The flange material, which is relatively lightweight and thin compared to the border material, is bunched up at the corners and provides additional surface area for attachment to the mattress. It should be noted that regardless of whether the flange is cut, the notches may be made by one or two knives of various types, for example, guillotine knives, roll dies or any other type known to those skilled in the art of textile manufacturing and processing. The only requirement is that the knives do not interfere with the accurate measurements of the length and width portions. The final severing cut may be made with the same or a different knife than the one used for the notches. 
     As will be readily apparent to those skilled in the art, the gusset-forming machine of the invention achieves the stated objectives by providing an automated measuring and cutting station. The measuring operation is performed accurately by drawing the web without tension with a positive traction drive. Once the sections are measured, notches are cut by utilizing the A and B perpendicular positions of the knife. After the notches are completed for a particular pillowtop, the knife is actuated at its center position C to sever the pillowtop gusset from the web. Material is provided to the measuring and cutting station  50  without tension due to the provision of a slack bin disposed directly upstream. The slack bin is equipped with sensors that provide control signals to generate additional slack from upstream sewing operations. The web entering the slack bin is formed in a sequential operation requiring careful alignment and tensioning of the border and flange materials. By providing an alignment and tensioning guide  22 , and a positive traction drive  24   b,  the folding, sewing, joining and the unfolding of the material is carefully controlled.