Abstract:
A blank non-adhesive label stock roll containing a continuous blank non-adhesive label sheet is printed as it is being unrolled to provide a multiplicity of pre-printed labels thereon. As the label sheet is being unrolled, each of the printed labels is partially cut along a peripheral edge thereof to leave a plurality of spaced apart uncut ties joining points along the peripheral edge to a scrim area of the label sheet to thereby maintain removable attachment of each of the pre-printed labels to the scrim area. Following printing and partial cutting of the labels, the label sheet is rerolled to form a pre-printed and pre-cut label stock roll, which is then controllably unrolled to permit selective removal of the pre-printed and pre-cut labels by an apparatus that conveys them for use in an external molding process.

Description:
BACKGROUND AND SUMMARY OF THE INVENTION 
       [0001]    This invention relates generally to in-mold labeling of plastic containers and, more particularly, to an apparatus and process for printing, cutting, and feeding in-mold labels to an external molding process. 
         [0002]    In the prior art, in-mold labels are typically printed on rolls of label stock, then rerolled and transported to a molding site, where the printed label roll is unrolled and cut to size for insertion into a mold. Cutting the labels by means of an expensive rotary die cutter, for example, positioned at each molding machine, is an operation that molding companies do not normally perform. Therefore, skilled operators must be hired to cover all 24-hour molding operations. 
         [0003]    In accordance with the illustrated preferred embodiment of the present invention, an apparatus and process for use in an in-mold labeling application utilizes a roll of label stock or web material containing a multiplicity of pre-printed non-adhesive labels. The labels are partially cut from the pre-printed roll, leaving only a few uncut peripheral ties by which each of the partially cut labels remains attached to the label stock. The label stock, with the pre-printed and partially cut labels still attached thereto, is then rerolled. The resulting roll is unrolled at the molding site to permit the labels to be easily pulled from the web material against the slight resistance offered by the ties. Advantageously, the present apparatus and process eliminates the need for expensive label cutting machinery and skilled operators at each molding machine. Label cutting will instead be performed at print shops where experienced operators are already present. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0004]      FIG. 1  is a schematic representation of the apparatus for handling in-mold labels of the present invention. 
           [0005]      FIG. 2  is a detailed pictorial diagram of the apparatus for handling in-mold labels of  FIG. 1 . 
           [0006]      FIG. 3  is a detailed pictorial diagram illustrating the sheet unwinding and lateral justification sections of the apparatus for handling in-mold labels of  FIGS. 1 and 2 . 
           [0007]      FIG. 4  is a detailed pictorial diagram illustrating the pinch roll section of the apparatus for handling in-mold labels of  FIGS. 1 and 2 . 
           [0008]      FIG. 5  is a detailed pictorial diagram illustrating the servo-driven conveyor section of the apparatus for handling in-mold labels of  FIGS. 1 and 2 . 
           [0009]      FIG. 6  is a flow chart of the electronic control steps implemented in and executed by a conventional electronic controller to control the apparatus for handling in-mold labels of  FIGS. 1 and 2 . 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0010]    Referring now generally to  FIGS. 1 and 2  and, for the details thereof, to  FIGS. 3-5 , there is shown an apparatus  100  for handling in-mold labels in accordance with the present invention that includes a label stock roll  1  containing a continuous label sheet  3  having one or more longitudinal lanes of non-adhesive labels or sets of labels  19  conventionally pre-printed thereon at predetermined spacing intervals. A distinguishing feature mark  15  is also pre-printed in association with each of the labels or sets of labels  19 . At the time of pre-printing the labels  19  on label sheet  3 , each of the labels  19  is partially cut by conventional means to a final label shape, leaving a plurality of uncut ties or tabs along the peripheral edge of each label by which each of the partially cut labels  19  remains attached to the waste portion or scrim of label sheet  3 . Label sheet  3  containing the preprinted and partially cut labels  19  is then rerolled to form label stock roll  1  for use by the apparatus  100  of the present invention. 
         [0011]    In use, rerolled label sheet  3  is unrolled from label stock roll  1  by means of a conventional servo motor  2 , the free end of label sheet  3  being routed around a series of rolls, the first of which is an active float roll  4  that serves primarily to maintain constant tension in the label sheet  3  and that also serves to provide feedback for controlling the speed of servo motor  2 . A plurality of rolls  5  serve as idler rolls. Label sheet  3  passes an optical sensor  6  positioned adjacent one of rolls  5  that is capable of detecting a splice in label sheet  3  to enable the in-mold labeling apparatus  100  to respond to detection of a splice in a chosen manner that prevents interruption of the flow of cut labels at the output thereof. An optical sensor  7 , positioned downstream from optical sensor  6  adjacent another one of rolls  5 , serves to resolve a distinguishing feature, such as a pattern or print, on label sheet  3  in order to laterally justify those patterns or prints to a set of pinch rolls  11 ,  12 , illustrated in  FIGS. 1, 2, and 4 . Label sheet  3  then passes beneath a passive float roll  8  which serves as a secondary means for maintaining constant tension in label sheet  3 . A sensor  9 , positioned adjacent another one of rolls  5 , serves to detect distinguishing feature mark  15  for the purpose of aligning label sheet  3  in a predetermined position longitudinally with respect to a set of pinch rolls  11 ,  12 . Sensors  6 ,  7 , and  9  may comprise conventional photoelectric sensors or one or more cameras. 
         [0012]    Label sheet  3  is routed downstream from sensor  9  between a set of pinch rolls  11 ,  12  that are driven by a servo motor  10 . Pinch rolls  11 ,  12  impart a sufficient clamping force to convey label sheet  3  from the idler rolls  5  to a conveyor  16  positioned downstream from pinch rolls  11 ,  12 . Conveyor  16  may be a conventional vacuum conveyor or a conventional belt conveyor. Conveyor  16  is driven by a servo motor  23  and is horizontally positioned to receive label sheet  3  at the output of pinch rolls  11 ,  12 . Before entering conveyor  16 , label sheet  3  is routed beneath a passive float roll  13  that is positioned between pinch rolls  11 ,  12  and the input end of conveyor  16 . A downward force applied to passive float roll  13  serves to create a controlled loop in label sheet  3  for maintaining a desire tension therein as it exits pinch rolls  11 ,  12 . This downward force may be produced by the weight of passive float roll  13  itself or by a conventional spring tensioning device, for example. The loop produced in label sheet  3  by float roll  13  permits the vacuum conveyor  16  and the pinch rolls  11 ,  12  to operate independently of each other, thus allowing each of them to reregister for the next index cycle without subjecting label sheet  3  to excessive tension that may result in tearing label sheet  3  itself or in tearing the tabs that connect each of the partially cut labels or sets of labels  19  from the scrim area, causing labels or sets of labels  19  to be improperly located. Thus, conveyor  16  is permitted to move while pinch rolls  11 ,  12  are stopped. Label sheet  3  may also be moved backward by pinch rolls  11 ,  12  in order to reregister label sheet  3  prior to the next index cycle performed by 7 pinch rolls  11 ,  12 . 
         [0013]    One or more scrim hold down assemblies  20  may be provided along conveyor  16  above label sheet  3 . Scrim hold down assemblies  20  are arranged to be vertically moveable, in response to compressed gas or some other conventional actuation force, between an up position and a down position. When in the up position, scrim hold down assemblies  20  are raised a sufficient distance above label sheet  3  to permit label sheet  3  to be freely longitudinally conveyed on conveyor  16 . When in the down position, scrim hold down assemblies  20  are lowered such that leading and trailing transverse bars  21 ,  22  thereof contact the scrim areas of label sheet  3  between longitudinally-adjacent ones of labels or sets of labels  19  to permit the partially cut labels or sets of labels  19  to be removed, either singly or in groups, by an external conventional pick and place head  18 , without disturbing the scrim areas. External pick and place head  18  is actuated by vacuum or some other conventional method to lift one or more of the labels or sets of labels  19  from label sheet  3  and to place them in position for further processing, such as on mandrels within a mold, for example. 
         [0014]    A plurality of vacuum plenums  17 , illustrated in the cut away portion of  FIG. 5 , may be provided along conveyor  16  to selectively apply a hold-down vacuum from an external source to conveyor  16 . The vacuum so applied serves to maintain label sheet  3  in a position of registration, fixed with respect to conveyor  16 , while label sheet  3  is being conveyed thereon. When the label sheet  3  has been conveyed to a predetermined label removal position, vacuum previously applied to vacuum plenums  17  is released, and the cut labels or sets of labels  19  are free to be removed by pick and place head  18 . An optical sensor  14 , located adjacent to conveyor  16 , detects each of the distinguishing feature marks  15  on label sheet  3  to facilitate alignment of the partially cut labels or sets of labels  19  in a position of registration, which is a predetermined longitudinal position obtained through precise control of the servo-driven conveyor  16 . In order to locate label sheet  3  in either its position of registration or its label removal position on conveyor  16  more precisely, servo motor  23  may be controlled to restart movement of conveyor  16  at a lower speed. 
         [0015]    Following removal of the cut labels  19  by pick and place head  18 , the scrim hold down assemblies  20  are actuated to the up position, and the scrim  24  is conveyed off the end of conveyor  16  during the next operational cycle. 
         [0016]    Operation of the apparatus for handling in-mold labels  100  of  FIGS. 1-5  may be further understood with reference to the flow chart of electronic control steps illustrated in  FIG. 6 , the steps of which may be implemented in and executed by a conventional electronic controller. A process start command is issued at control step A. A Pinch Roll Seek Distinguishing Feature command is then issued at control step C to cause master servo motor  10  to rotate in the forward direction until sensor  9  has detected a distinguishing feature that serves to verify the longitudinal position of label sheet  3 , following which servo motor  10  is commanded to stop rotating. A Gear Pinch Roll and Conveyor command is then issued at control step C to electronically synchronize the servo motors  10 ,  23  such that servo motor  10  functions as the master, and servo motor  23  functions as a slave. A Ready for Cycle command is then issued at control step D to maintain the apparatus  100  in a ready state. An Actuate Scrim Hold Down To Up 
         [0017]    Position command is then issued at control step E to move the scrim hold down assemblies  20  to the up position. An Index Pinch Roll and Conveyor command is next issued at control step F to cause servo motors  10 ,  23  to rotate in the forward direction for a predetermined distance. Servo motors  10 ,  23  are then commanded to electronically decouple from each other at control step G, and servo motor  10  is commanded to stop rotating. A Vacuum Conveyor Seek Distinguishing Feature Mark command is then issued at control step H to cause servo motor  23  to rotate in the forward direction until sensor  14  has detected distinguishing feature mark  15  to thereby verify the longitudinal position of label sheet  3 , following which servo motor  23  is commanded to stop rotating. An Actuate Scrim Hold Down to Down Position command is then issued at control step I to move the scrim hold down assemblies  20  to the down position. Following execution of control step I, electronic control of the apparatus  100  is directed back to control step B.