Automatic high speed; labeling system having an improved label stripper

An automatic high speed labeling machine with an improved label stripper is provided capable of applying 700 to 1,000 labels to individual produce items in a single lane, without tearing the label carrier strip. The improved label stripper has a contoured surface wherein only the center section contacts the label carrier strip. The edges of the carrier strip are prevented from contacting the label stripper surface.

BACKGROUND

This invention pertains generally to the automatic labeling of individual produce items. Labeling speeds have now reached about 700 to 1,000 labels per minute for a single lane. At these high speeds, a significant problem is that label carrier strips tend to tear at their edges when the carrier strip becomes misaligned with the label stripper as the carrier strips are drawn over the label stripper. When the prior art carrier strips become misaligned, the edges of carrier strips are in greater tension than the center of the carrier strips, causing the edges to tear at the high speed noted above as the strips are drawn across the label stripper. Torn label carrier strips cause labeling down time, which in turn can cause costly downgrading of fresh produce ready to be labeled.

Another problem resulting from high labeling speeds is that polymer film labels utilizing hot melt adhesives become very flexible at elevated ambient working temperatures. The highly flexible labels tend to resist being separated from the label carrier strip, and produce items fail to be labeled. This problem becomes serious in that labeling speeds must be reduced significantly at elevated, ambient working temperatures (about 90° F. and higher) to avoid unlabeled produce. Elevated working temperatures are common in processing plants at harvest time. Reducing labeling speeds is not a satisfactory option for produce owners. A more reliable system for stripping flexible labels is needed.

BRIEF SUMMARY OF THE INVENTION

The invention provides a relatively simple, yet elegant system for minimizing the tension at the edges of the label carrier strip to reduce tearing, and simultaneously increasing the tension at the center of the carrier strip to more efficiently separate highly flexible labels from the carrier strip.

In a nutshell, the invention provides a label stripper having a novel “contoured surface” which engages only the center of the carrier strip as opposed to the typical flat edge of the prior art, which engages the entire width of the carrier strip. Whereas the prior art flat edge label stripper engages the entire width of the label carrier strip, the novel “contoured surface” includes a central “stripping segment” which is positioned in the center of the pathway of the carrier strip and engages only the central region of the carrier strip. The novel “contoured surface” also includes a pair of “separation segments” positioned laterally on opposite sides of the central stripping segment and which prevent the edges of the carrier strip from running against or engaging the surface of the label stripper. In effect, the edges of the carrier strip are separated from and do not engage the label stripper and in effect, are allowed to “float” past the label stripper.

A primary object of the invention is to reduce tearing of the label carrier strip at high labeling speeds; i.e. 700 to 1,000 labels per minute for a single lane.

Another object is to increase the speed, reliability and efficiency of stripping highly flexible labels from a label carrier strip.

A further object is to provide a high speed labeler having a label stripper with a contoured surface that tends to self-center the carrier strip

Further objects and advantages will become apparent from the following disclosure and drawings wherein:

DETAILED DESCRIPTION OF THE DRAWINGS

FIGS. 1-9Care not to scale and are exaggerated to illustrate the problems with the prior art and to illustrate the invention.

FIGS. 1-3illustrate how the prior art systems tend to cause the tearing problem noted above.FIG. 1shows a label carrier strip10moving along a longitudinal axis A1-A1toward a stationary prior art release pin (or label stripper)30. Pin30is a straight pin with a cylindrical or flat cross-section, as known in the art. It is significant to note that the surface of prior art pin30that contacts or engages label carrier strip10is flat. Carrier strip10carries a plurality of labels21-24along its longitudinal center, as known in the art.FIG. 2is a side elevational view ofFIG. 1. As shown inFIGS. 1 and 2, label24is being successfully stripped or released from carrier strip10to be applied to produce or other items. Longitudinal axis A1-A1of carrier strip10is preferably kept perpendicular to the longitudinal axis X1-X1of pin30, wherein the carrier strip is “aligned” with release pin (or label stripper)30. It should be noted that the length of the flat pin (or stripper)30on the X1-X1axis is greater than the width of carrier strip10. The carrier strip10has its entire width drawn across the pin or label stripper30. Also, the angle Z through which carrier strip10bends is between 60° and 340° as generally known in the art.

FIG. 3illustrates label carrier strip10ofFIG. 1when, for various reasons, strip10becomes misaligned as shown by angle “M” and moves along longitudinal axis A2-A2which is not perpendicular to axis X1-X1of pin30. The edge11of carrier strip10adjacent pin30is subjected to increased “point” tension at point11aand is susceptible to tearing. The edge most susceptible to tearing is edge11, which forms an obtuse angle with axis X1-X1of pin30. When carrier strip10becomes torn, labeling down time results, as noted above.

FIGS. 4A and 4Billustrate the second problem noted above—that hot melt adhesive labels driven at speeds of 700 to 1,000 labels per minute across a prior art release pin30tend to remain adhered to carrier strip10when ambient working temperatures are relatively high, such as 90° F. As shown inFIG. 4B, which is a side elevation ofFIG. 4A, hot melt adhesive label24asimply remains attached to strip10as strip10is drawn across pin (or label stripper)30, resulting in an unlabeled produce item.

FIGS. 5A-5Cillustrate a prior art release (or stripper) plate130, which is a flat or planar rectangular metal plate having a body131and two mounting ears132and133. The label carrier strip110(FIG. 5C) with label121runs against lower edge135, which is flat. Both problems noted above occur when using plate130, since the edges111and112of carrier strip run against the stripping surface135and are subject to the “point” pressure described above. As shown inFIG. 5B, plate130lies in a plane.

FIG. 6A-6Cillustrate a first embodiment of the invention, wherein label stripper230comprises a generally rectangular metallic body231, two mounting ears232and233and a contoured surface240which includes a central stripping segment245against which the center of label carrier strip210(FIG. 6C) runs or engages. Contoured surface240also includes first and second separation segments241,242respectively, which are positioned laterally on opposite sides of said central stripping segment and which in the embodiment shown inFIG. 6Aare curved and have surfaces inclined in a direction away from the path of the label carrier strip. The central stripping segment245is also curved. The contoured surface240in this embodiment is one continuous convex curve, extending across the entire surface240and having a convex shape relative to the carrier strip210(FIG. 6C). The contoured surface240has a height d1of approximately 1 mm for a width of surface240of 25 mm. Label stripper230lies in a plane as shown inFIG. 6B. As shown inFIG. 6C, the curved shape of separation segments241and242continuously separates the edges211,212of the carrier strip from the contoured surface240, and relieves the tension otherwise formed at the edges211and212of carrier strip210, up to a designated, allowable degree of misalignment. As used herein, the term “misalignment” is the degree to which the longitudinal axis of the label carrier strip is not perpendicular to the longitudinal axis X2-X2of release pin130(FIG. 5B) or label stripper230(FIG. 6B) as indicated above by angle “M” inFIG. 3between axis X1-X1and a perpendicular line17to axis X1-X1.

FIG. 6Bis an elevational view on the line6B-6B ofFIG. 6A. Label stripper230lies in a plane and has a longitudinal axis X2-X2.

As shown inFIG. 6C, the smooth, curved separation segments241and242continuously separate the first and second edges211,212of carrier strip210from the contoured label stripper surface240, minimizing tension in those edges to reduce tearing of the carrier strip210, and simultaneously maximizing tension along the center region215of carrier strip210(along which said labels210are positioned) to increase efficiency of label removal. The edges211,212of carrier strip210move past the label stripper230without touching it or running against it. It is significant to note that the central stripping segment245of label stripper surface240is the only portion of contoured surface240against which the carrier strip210runs. This increased tension on the center of the carrier strip increases performance of label stripper230in releasing or stripping labels. This feature is most evident with polymer film labels utilizing hot melt adhesives, which tend to become more flexible at elevated temperatures. Unfortunately, this additional pressure can result in increased web breaks due to heavy die cuts created at the time of label manufacturing. We have found that the efficiency of stripping labels using hot melt adhesives is increased by at least 20% using the embodiment ofFIGS. 6A-6C.

It is also significant to note that inFIG. 6C, the continuously smooth curve of surface240creates an inherently “self-centering” aspect to the problem of misalignment. If the edge212of carrier210starts drifting to the right inFIG. 6C, the entire carrier strip210will drift back to the left, because of the curvature and smoothness of surface240.

A second embodiment of the invention is shown inFIGS. 7A and 7Band differs from the embodiment shown inFIGS. 6A-6Cin one respect—a center notch350in contoured surface340. Label stripper330comprises a generally rectangular metallic body331, two mounting ears332and333, and a contoured surface340having a central stripping segment345across which the label carrier strip (not shown inFIGS. 7A and 7B) runs. The curved surface340has a smooth, convex shape relative to the carrier strip. Separation segments341and342on opposite sides of central stripping segment345form convex curves relative to the carrier strip. The curve forming surface340has a height d3of about 1.0 mm for a surface340having a length of 25 mm. The curved, separation segments341and342reduce and minimize tension in the edges of the carrier strip. The curved central portion345concentrates tension in the central portion of the carrier strip to increase stripping efficiency of hot melt adhesive labels. To combat the point pressure in the center of the label carrier strip, a center notch350is added to distribute the pressure across a designed length d2. Notch350has two arms351and352, which extend a distance d2along the length of contoured surface340. Distance d2is preferably 2-4 mm for a contoured surface350having a length of 25 mm. The curve forming contoured surface340has a height d3of about 1 mm for a surface340having a length of 25 mm. The notch350will help relieve tearing of the carrier strip due to die cut issues, but will also reduce the label stripper performance. In a field trial, this resulted in the maximum working temperature to be reduced by 20° to maintain release of >97% of the labels, which is typical of the simple curve of edge235at 90° F.

FIGS. 8A and 8Billustrate a further embodiment in which label stripper530is the same as label stripper230shown inFIGS. 6A and 6Babove, except for one difference. The difference is that label stripper230is planar as shown inFIG. 6B, whereas label stripper530is a curved plate relative to the direction of travel519of carrier strip510(shown inFIG. 8Bonly for clarity) and forms a convex surface relative to the direction of travel519of carrier strip510. Contoured surface540is a continuous curve, having a central stripping segment545and separation segments541and542.FIG. 8Bshows carrier strip510with first and second edges511and512. Label521is on the longitudinal center of strip510.

FIGS. 9A-9Cillustrate another embodiment in which label stripper630has a relatively large central stripping segment645of contoured surface640. The label stripper630has a body631and two mounting ears632,633. Two separation segments641and642are inclined segments with straight surfaces. The central stripping segment has a flat surface parallel to the carrier strip pathway which extends laterally more than 75% of the width of the carrier strip as shown best inFIG. 9C(FIG.9C is the same asFIG. 9Awith the carrier strip). This embodiment applies a relatively uniform tension across the central portion of the carrier strip. As shown inFIG. 9C, the edges611and612of carrier strip are continuously separated from the contoured surface640of the label stripper630and simply pass through stripper630without contacting any part of surface640.

FIGS. 10A and 10Billustrate how the embodiment ofFIGS. 9A-9Cmay be modified by using a curved plate730which forms a convex surface relative to the direction of travel of the carrier strip, similar to the curved plate shown inFIG. 8B. This feature assists in separating hot melt adhesive labels from the carrier strip. Label stripper730has a metallic body731and two mounting ears732,733. Label stripper730has a contoured surface740having a central stripping segment745and first and second separation segments741,742.FIG. 10Bshows carrier strip710with label721in the center of strip710moving in a direction719across stripper730.

FIGS. 11 and 12illustrate one prior art labeling machine in which the present invention will operate. They are reproductions of FIGS. 2A and 3 from U.S. Pat. No. 9,457,587, with reference numbers modified.FIG. 11shows an automatic high speed labeling machine1,005used to apply labels to individual items of produce1,006-1,008. A detachable label cassette1110contains a large number of labels on an elongated carrier strip. A label applicator1,115having a plurality of bellows1045carried on a rotary head1,040includes a label stripper1,185(FIG. 12) to strip individual labels1,142a-1,142d(FIG. 12) from a label carrier strip1,141and transfer said labels onto the tip1,041aof a single bellow1,041and thereafter onto individual items of produce1,006-1,008.

In accordance with the above disclosure, an improved method of high speed labeling is provided in which a contoured surface such as240,340,540,640,740is formed having central stripping segments245,345,545,645and745. Each contoured surface has first and second separation segments, as described above.

Each contoured surface is positioned and shaped to cause the center215(FIG. 6C) of carrier strip210to continuously engage the central stripping segment such as245(FIG. 6C) to continuously strip labels. Both of the separation segments241,242(FIG. 6C) are shaped and positioned to continuously separate the first and second edges211,212of the carrier strip from the contoured surface240, allow edge211,212to move past the label stripper230without running against it or touching it. The method simultaneously maximizes tension in the center215of carrier strip210to increase efficiency of label removal, and minimizes tension in the first and second edges211,212of carrier strip210to minimize tearing of the carrier strip. Each contoured surface remains stationary during the labeling process.

The above described method allows the labeling machine to apply between 700 and 1,000 labels per minute by a single lane, without tearing the label carrier strip. The method also increases efficiency of label removal by more than 20% for hot melt adhesive labels.

The invention disclosed herein may be used in any produce labeling machine in which release or stripping pins or plates are utilized to separate individual labels from a carrier strip. The invention is especially helpful in the labeler shown in U.S. Pat. No. 9,457,587, incorporated herein by reference as though set forth in full. The label stripper may be adjustably mounted to apply greater or less tension in the carrier strip.