Patent Application
20160114501
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.
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.
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.
Referring now generally to
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
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.
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.
A plurality of vacuum plenums 17, illustrated in the cut away portion of
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.
Operation of the apparatus for handling in-mold labels 100 of
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.
