Abstract:
Tab length is controlled in a tape applicator by adjusting the position of a tension roll as the diameter or periphery of the tape supply roll is changed to increase the force pulling the tape from the supply roll as the diameter of the tape supply roll decreases without significantly changing the tension in the tape.

Description:
FIELD OF INVENTION 
       [0001]    The present invention relates to a tape applicator for apply tape to seal a case or carton and particularly to an improved tape tension system to simplify obtaining of a uniform tape tab length. 
       BACKGROUND OF THE PRESENT INVENTION 
       [0002]    In the packaging of goods in containers, such as corrugated cartons or the like, it is common practice to use a tape sealing machine with a tape applicator to apply a strip of sealing tape along one end, across the top (or bottom) generally formed by a pair of opposed flaps and along another end of such a container. The adhesive tape is usually of Bi-axially Oriented Poly-Propylene (BOPP) film with an adhesive layer on one side and a release coating on the other side for ease of unwind. To properly seal the flaps of the carton in order to provide sufficient holding force to the carton, The adhesive tape normally applied first to the one end which in most machines forms a vertical surface, from this vertical surface of the carton, across the horizontal surface formed by the pair of opposed flaps to the other end of the carton which normally is a second vertical surface so the shoulders or the corners of the carton formed at the intersections of the vertical and horizontal surfaces are tightly wrapped. The vertical portions of the tape on each of the ends or the carton are each referred to as a tape tab. The length of the tab is preset by the tape applicator to provide a desirable amount of adhesive holding force to the carton. The tab length is usually preset from 2″ to 2.5″, excessive tab length is costly and un-effective, inadequate tab length reduces the adhesive area and holding force to the carton and causes a defective package. 
         [0003]    The tape applicator automatically applies and cut off the tape to seal each carton as the carton advances passed the tape applicator usually by being carried on a conveyor of the packaging machine. The tape is supplied from a tape roll mounted on the packaging machine frame or usually mounted on the frame of the applicator which forms part of the machine. 
         [0004]    As is well known a proper tape application system involves the source of tape, tape delivery; tape applying, tape cutting, and tape wipe down. 
         [0005]    Most major problems encountered in carton taping using a conventional tape applicator are related to the tape tension as follows:
       (1) Low tension:
           Results in loose and wrinkled tape on carton; tape not cutting properly; extended tape tabs   
           (2) High tension:
           Results in the tape being over-stretched and elongated causing the tape to shrink and pull back; premature tape cutting; tape flagging; tape snap back and crumple; shortened tape tab lengths   
               
 
         [0010]    There are two manual tension adjustments in a conventional tape applicator, namely (1) mandrel tension control, (2) clutch roller tension control which can partially address the abovementioned tension related issues and the variable unwinding (peel-off) force from the tape dues to different adhesive formula (hot melt, acrylic or rubber); release coating; width of tape (2″ or 3″); application temperature; etc. A third tension adjustment (3) may be provided by an added-on attachment in the form of a nip roller mounted at the free end of a dancer arm and biased against the periphery of the tape roll,
       (1) Tape Mandrel Tension Adjustment:
           The mandrel tension adjustment normally consists of a hub to hold the hub of the tape roll, rotatable on a shaft with friction washers, compression spring and adjusting knob as a mean to provide a rotational drag on the tape roll as the tape being dispensed. It is the first stage of tape tension control and is applied at the source of tape supply, and functions to prevent the tape roll from free spinning; over-spinning or tape over-stretching. The amount of tension adjustment is also based on the unwinding force required for the tape being used, for example: low tension setting for sticky or wider tape, higher tension setting for narrower width and tape with a release coating.   In carton sealing, the carton are being deliver in space sequence one by one, requiring the tape to be pulled from the tape roll intermediately. The tape roll rotation starts and stops at every taping cycle, it tends to over-spin every stop cycle after tape cutting. Over-spin of tape roll creates loose tape, which affects the tape cutting (tape un-cut or cut with extended tab length) as well as taping consistence in the following taping cycle.   More rotational drag is required to reduce the over-spinning, particularly when tape is being drawn from a new roll of tape with a large diameter (15″) due to the additional mass and inertia.   If the drag applied at the tape mandrel is too high it will normally lead to tape breakage; stretched and elongated tape; premature tape cutting; tab crumpling and/or shortened tabs.   
           (2) Clutch Roller Tension Adjustment:
           Generally the tension adjustment mechanism used in the clutch roll is similar to the mandrel tension adjustment mechanism using a compression spring; friction washers and an adjusting knob to adjust rotational drag. The clutch roller also is provided with a one-way clutch bearing to permit the tape to advance toward an applicator roll that applies the leading end of the tape to the carton while preventing the tape travel in reverse direction i.e. back toward the tape roll. The clutch roller&#39;s surface is knurled to release the adhesion of the tape.   The tension control at the tape roll mandrel is in essence the farthest from the point of application of the tape to the carton and provides a first stage of tension control applied to the tape. The clutch roller is the second stage of tape tension control of the tape and is positioned on the tape path from the tape roll to the applicator roll at an intermediate location between the tape roll and applicator roll. The clutch roller provides a secondary tension control to supplement the tension adjustment of the tape roll mandrel. Its position is closer to the point of application and tape cutting, its tension adjustment affects proper tape cutting, taping quality and tends to stabilize the tape for the tape application cycle.   Similar to the tape roll mandrel adjustment, low tension setting on the clutch roller leads to loosely adhered wrinkled tape on the carton; tape not being properly cut or tape an extended tab length. High tension setting leads to stretched tape on the carton which shrinks and causes the tabs to pull backwards; tape breakage; tape cut prematurely; tape crumple; and/or the tape to snap away from the application roller; and/or generate a shortened length tab.   
           (3) A nip roller dancer arm   A nip roller at the free end of a dancer arm tends to stabilize the tape tension at the tape source. The dancer arm is spring bias to [press the nip roller against the circumference of the tape roll, the nip roller governs the position of tape being peeled off from the tape roll. The round surface of the roller supports the tape as it peels off the tape roll as the tape roll unwinds and provides a smoother tape release thereby to minimize jerky movement of the tape which may cause tape breakages.   It is believed that all tape applicators on the market are equipped with the above mentioned two manual tension adjustments and some may also include the nip roller dancer arm. Generally the tape tension is adjusted to a desirable level based the type of tape being used before startup of the machine in order to provide a reliable tape closure. However, it is well known that the tape&#39;s tension changes as the tape is being applied. Specifically, the tape tension increases gradually as the tape roll is depleted from a new roll (Max. 15″diameter) down to a smaller roll (Min. 3.3″ diameter) during the tape sealing operation. The increased tape tension leads to tape breakages, tape shrinkage, premature tape cut, tape not being applied due to snap back or shortened tab length etc. creating batches of defective packaged cartons. All these problems appear mostly after the tape roll has been depleted down to approximately 4″ to 5″ diameter. To avoid these problems, there are three common practices in the industry (1) Monitor the tape roll, re-adjust the tension control manually once or twice based on the remaining size of the tape roll. (2) Install a new tape roll and discard the remaining tape roll before the tape is fully depleted. (3) Use an over-graded thicker tape which can sustain a higher tension, allow an over-extended tab length in the initial low tension setting for new roll to compensate the increases of tape tension which shortens the tab length as the tape is depleting. (This approach resolved some of the problem but it also leads to the problem of cutting a thicker tape with low tension). All three approaches are not ideally effective and generally result in added production down time, waste of tape and increase cost of tape, etc.   The currently available tension controls and the add-on nip roller dancer arm in a conventional tape applicator can only be preset to accommodate a constant condition such as tape peel-off unwind force and resistance through the tape path etc., they are not sufficient to control the changing tape tension as occurs during the taping operation i.e. as the tape is being dispense and the diameter of the tape roll changes when the tape roll goes from a large roll to a smaller roll. The changes of tension originate mainly from the drag preset at the tape mandrel.   A simple example illustrates how the changes of tape roll size affect the changes of tape tension: A new roll of tape with a 15″ diameter dispenses 24″ long tape on a 20″ long carton rotates ½ revolutions to complete one taping cycle. On the other hand when the tape roll has depleted gradually down to a 3.5″ diameter tape roll, it must now rotate 2 revolutions to dispense the same 24″ long tape for the same 20″ long carton. The tape tension increase significantly dispensing the same length of tape from the smaller roll since it has to overcome the additional rotations with the rotational drag initially preset to rotate for ½ revolutions.       
 
         [0025]    Tape applicators as generally used to apply tapes to seal a carton operate by providing a leading tape which is wiped onto the leading face of a carton or case being sealed and secured thereto and then is applied over the adjacent edge of the case and along the top (or bottom of the case. The length of tape applied to the leading face of the case or carton i.e. extending from the adjacent edge to the adjacent end of the tape is normally referred to as the tab and the length of this tab in conventional machines changes significantly unless in the case of conventional machines the tape tension is adjusted as the diameter of the tape roll from which the tape is being drawn changes. Tension adjustment systems of the prior art as described above are not done on the fly and in any event do not generally provide adequate control to maintain the tab length reasonably constant as the diameter of the tape roll changes. The present invention provides a mechanism that maintains the tab length about the same length as the diameter of the tape roll changes. 
         [0026]    The convention tape applicators as above indicated generally direct tape from the tape roll to an entry roll from which the tape passes onto a one way clutch roll and from there to a front applicator roll that applies the leading end of the case being sealed. It is known to provide a dancer arm with a nip roll at its free end and to lead the tape over the nip roll which is pressed against the periphery of the tape roll and facilitate peeling of the tape off the tape roll; see for example U.S. Pat. No. 4,592,188 issued Jun. 3, 1986 to Marchetti. 
         [0027]    It is also known to provide slack in the tape between the clutch roll and the tape roll by replacing a fixed entry roll as commonly used with an entry roll that is mounted on the free end of a dancer arm that reciprocates the entry roll between a position adjacent to and a second position spaced farther from the clutch roll at the appropriate time in the taping cycle to generate slack in the tape between the tape roll and the clutch roll; see U.S. Pat. No. 8,327,902 issued Dec. 12, 2012 to Lam. 
         [0028]    U.S. Pat. No. 8,176,959 issued May 15, 2012 to Lam teaches a multi-purpose machine that may be converted to apply tape as a conventional C-clip where the tape extends generally up one side of a case across the top (or bottom) and the down the side of the case opposite the one side or an L-clip where the tape extends up one side around a corner at the top (or bottom) of the case and then part way along the top (or bottom) of the case. The patent shows the clutch roll and inlet roll both mounted in fixed relationship on a dancer arm to accommodate movement of the front applicator arm and roll to an over travel position when L-clips are to be applied. 
       Brief Description of the Present Invention 
       [0029]    It is an object of the present invention to provide an improved tape applicator where tab length is better controlled. 
         [0030]    Broadly the present invention relates to a tape applicator for applying a sealing tape to a carton, said tape applicator having a frame, a tape roll mounting having a hub on which a roll of tape to be applied to seal said case may be mounted, a tape path between a periphery of said roll of tape and a tape applicator roll positioned to apply tape to said case as said case is moved relative thereto, rolls defining said tape path, one of said rolls being a one way clutch roll to permit tape movement toward said tape applicator roll and inhibiting tape movement in the opposite direction, a dancer arm pivotably mounted adjacent to one end of said dancer arm on said frame and a nip roller mounted on said dancer arm adjacent to an end of said dancer arm remote from to said one end, means biasing said dancer arm to press said nip roller into contact with said periphery of said roll of tape, said nip roller defining an initial portion of said tape path, the improvement comprising; 
         [0000]    a tab length control comprising a tension roll coupled to said dancer arm and defining a portion of said tape path between said nip roller and said one way clutch roller, said tension roll being coupled to said dancer arm so that as said dancer roll moves toward said tape mounting as said roll of tape is being depleted said tension roll moves relative to said clutch roller thereby changing said tape path to adjust the forces applied at said nip roller as said periphery of said tape roll decreases. 
         [0031]    Preferably said tension roll is mounted adjacent to a free end of an auxiliary mounting arm that is directly connected to said dancer arm. 
         [0032]    Preferably said tension roll is mounted on a lever arm that is pivotably mounted on said frame and means is provided to bias a camming projection of said lever arm against said dancer arm so that said tension roll moves with said dancer arm and in accordance with the interaction of said camming projection with said dancer arm. 
         [0033]    Preferably means are provided to adjust the position of said tension roll relative to said dancer arm. 
         [0034]    Preferably said tab length control is positioned remote from said tape applicator. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0035]    Further features, objects and advantages will be evident from the following detailed description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings in which; 
           [0036]      FIG. 1  is a schematic illustration of one form of the present invention as applied to a conventional or well known tape applicator showing the applicator in more detail than in the subsequent views. 
           [0037]      FIG. 2  is a schematic illustration with parts omitted for clarity of  FIG. 1  embodiment of the present invention illustrating the tape path when tape is being dispensed from a full roll of tape 
           [0038]      FIG. 2 a    is a schematic illustration of the tab length generated when tape is being dispensed from a full roll of tape using the present invention as shown in  FIG. 1 . 
           [0039]      FIG. 3  is a schematic illustration of embodiment of the present invention shown in  FIG. 1  illustrating the tape path when tape is being dispensed from an almost depleted roll of tape. 
           [0040]      FIG. 3 a    is a schematic illustration of the tab length generated when tape is being dispensed from an almost depleted roll of tape using the present invention as shown in  FIG. 1 . 
           [0041]      FIG. 4  is a schematic illustration of anther embodiment of the present invention showing the tape path from a full roll. 
           [0042]      FIG. 5  is a schematic illustration of anther embodiment of the present invention showing the tape path from an almost depleted tape roll. 
           [0043]      FIG. 6  shows the tape supply and tension positioned remote from the tape applicator. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0044]    Attention is directed to  FIG. 1  which illustrates the preferred form of the present invention as applied to a tape applicator  10  for applying sealing tapes to cartons  11  ( FIG. 2 a    or  3   a ). As shown the tape applicator  10  has a conventional front applicator arm  12  pivotably mounted to the frame  14  as indicated at  13  and carrying an applicator roll  16  adjacent to its free end. The applicator roll  16  presses the adhesive side of a tape  18  being used to seal a case or carton  11  against the approaching face of the carton  11 . As is known the applicator roll or roller  16  may be replaced by wipers or applicators of various forms but a roll is preferred and the use of the term applicator roll or roller is not to be interpreted as excluding these other devices. The applicator  10  as is normal the case also includes the rear wiper arm  20  pivotably mounted on the frame  14  as indicated at  21  and having a wipe down roll or the like  22  at one side of the mounting  21  and connected to a push rod  24  on the opposite side of the mounting  21  as indicated at  26 . Also connect at  26  to the rear arm  20  is a spring  28  that in the illustrated arrangement biases the arm  20  to rotate clockwise around the pivotal mounting  21 . The push rod  24  interconnects with the front applicator arm  12  as indicated at  30  so that the spring  28  urges the arm  12  to the starting position as shown in  FIG. 1 . 
         [0045]    A suitable cut-off mechanism  31  is mounted on the frame  14  to function in the normal manner. 
         [0046]    A one-way clutch roll  32  is rotatably mounted on the frame  14  and forms part of the tape path  34  which will be described in more detail below. This one-way roll  32  is equipped with an adjustable drag applying mechanism and one way clutch mechanism as indicated schematically at  33  and is generally used to apply added drag to the tape  18  and to permit the tape  18  to travel only in the direction of the applicator roll  16 . 
         [0047]    A roll of tape  36  from which the tape  18  is drawn in operation is mounted on a hub  38  which in turn is mounted to a mast  40  extending from the frame  14 . The hub mounts the roll  36  in the normal manner and is provided with a conventional adjustable drag applying mechanism as schematically indicated at  42 . 
         [0048]    The tape  18  is withdrawn from the tape roll  36  by passing around a nip roll  44  which is rotatably mounted adjacent to the free end of a dancer arm  46  pivotably mounted on the frame  14  as indicated at  48 . The dancer arm  46  is biased by spring  50  extending between the arm  46  and the mast  40  to press the nip roll  44  against the periphery  52  of the roll  36 . 
         [0049]    The apparatus described above is found in many tape heads currently in use. 
         [0050]    The present invention provides a tab length control  100  which in the embodiment shown in  FIG. 1  is directly connected to the rape applying portion  102  of the tape applicator  10 . In the embodiment of  FIG. 1  the tab length control  100  incorporates a dancer arm  46  having an auxiliary mounting arm  54  projecting laterally there from in a direction away from the roll  36 . The arm  54  mounts a tension roll  56  adjacent its free end. As indicated schematically by the reversible mutually perpendicular arrows  58  (which is optional) the position of the auxiliary arm  58  relative to the dancer arm  46  may be changed e.g. along and/or projecting from the dancer arm  46  i.e. may be made adjustable if desired so that the position the roll  56  may be adjusted as desired to facilitate accommodation of tapes with different characteristics by changing the relationship of roll  56  to the arm  46  which will change the positioning of the roll along the tape path  34 . 
         [0051]    With the present invention the tape path  34  extends from the periphery  52  of the tape roll  36  about the nip roll  44  then over the tension roll  56  then the one-way clutch roll  32  and from there to the applicator roll  16 . It will be apparent that this path  34  changes as the tape roll  36  is depleted from the full roll  36 F in  FIG. 2  to the depleted or almost empty roll  36 E shown in  FIG. 3 . In the illustration of  FIGS. 2 and 3  as shown in  FIG. 2  with the full roll  36 F the wrap of the tape  18  around the periphery tension roll  56  (contact between) extends for about 120° and the wrap of the tape  18  around the clutch roll is about 125° degrees i.e. with dancer arm  46  positioned to the far right in the illustration by contact of the nip roll  44  with the periphery  52  of the full roll  36 F. As the tape roll  36  is diminished the tension roll  52  is moved relative to the clutch roll  32  around the axis defined by the mounting  48  of the dancer arm  46  to the frame  14  to the depleted or empty roll  36 E position shown in  FIG. 3 . In the full roll  36 F position the tension roll  56  as a percentage of the total span between the rolls  44  and  32  is less than it is when in the empty roll  36 E position. When the dancer arm  46  reaches the position shown in  FIG. 3  the wrap around the tension roll  32  has been reduce to about 90° and the warp around the clutch roller to about 70°. In the depleted roll position of  FIG. 3  a higher percentage of the forces applied by the tension in the tape  18  are applied at the nip roll  44 . 
         [0052]    As above described as the tape roll  36  is depleted and the size (diameter) of the roll  36  gradually reduces as the tape  18  is pulled there from until it reaches the size of the depleted roll  36 E shown in  FIG. 3 . In this position the dancer arm  46  continues to hold the roll  44  against the periphery  52  of the roll  36  and is rotated counter clockwise about axis  48  which changes the wraps around the clutch roll  32  and tension roll  56  as above described by moving the tension roll  52  relative to the one way clutch roll  32 . This action gradually increases the force (tension) applied by the tension in the tape  18  at nip roll  44 . 
         [0053]    It will be apparent that the tension applied to the tape  18  need not change significantly even if the force required to peel the tape  18  from the roll  36  changes provided the distribution of the forces applied by the tension in the tape  18  is adjusted to apply more force at nip roll  44  as the periphery  52  of the roll  36  decreases. Thus tension in the tape  18  may be about the same when the roll  56  is in the  FIG. 2  or  FIG. 3  positions. In  FIG. 2  position of roll  56  less force is applied at nip roll  44  than the force applied at nip roll  44  when the roll  56  is in the  FIG. 3  position. Thus when a lower force is required to pull the tape  18  from the tape roll  36  as is the case when the tape  18  is being dispensed from a full or new as shown at  36 F in  FIG. 2  the percentage of the available force being transmitted by tension in the tape  18  at the nip roll  44  is less. On the other hand when the a higher force is required to pull the tape  18  from the tape roll  36  i.e. when the tape roll  36  is depleted as shown at  36 E in  FIG. 3  the percentage of the available force being transmitted by tension in the tape  18  at the nip roll  44  is higher. Thus repositioning the tension roll  56  as described above applies more force at the nip roll  44  to pull the tape  18  from the roll when required without significantly changing the tension applied to the tape  18  i.e. the tension as normally required to pull the tape  18  from the empty roll  36 E of  FIG. 3  In this manner the tension applied to the tape  18  is maintained more uniform and as result as shown in  FIGS. 2 a  and 3 a    the length H 1  and H 2  of the tabs  60 F and  60 E are about the same regardless of whether the tape  18  is being pulled from a full tape roll  36 F ( FIG. 2 ) or a depleted tape roll  36 E ( FIG. 3 ) and the tab length will remain relatively constant as the tape roll  36  is depleted from the size of roll  36 F to the size of tape roll  36 E. 
         [0054]    In the  FIGS. 4 and 5  embodiment the auxiliary arm  54  has been replaced with a separate cam arm  70  which is L shaped in the illustrated arrangement and is pivotably mounted to the frame  14  on the same axis as the clutch roll  32 . The L shape is provided by its arms  71  and  73  extending from opposite sides of its axis. The arm  70  mounts the tension roll  56  adjacent to the free end of arm  71  which extend on the side of the clutch roll  56  adjacent to the nip roll  44 . The arm  70  is biased via spring  72  connected to the other arm  73  to hold a camming projection  74  on the arm  71  against the dancer arm  46  so that the tension roll  56  is repositioned in the same manner and acts in the same manner as described above with reference to  FIGS. 2 and 3 . The camming projection  74  which interacts with the dancer arm  46  provides a further means to adjust the position of the tension roll  56  as the tape roll is depleted from full  36 F to depleted  36 E. In this  FIG. 6  embodiment the tension roll  56  moves with said dancer arm  46  and in accordance with the interaction of said camming projection  74  with said dancer arm  46 . The positioning of the tension roll  56  relative to the dancer arm  46  may be further modified by changing the interaction of the camming projection  74  with the dancer arm  46  i.e. the movement of the tension roll  56  as the tape roll  36  is being depleted may be finer tuned to the tape roll being used. 
         [0055]      FIG. 6  shows a further embodiment of the present invention wherein the tension control  100  is positioned remote from the tape applicator  10  normally in some convenient location on the machine frame  200  of the machine with which the applicator  10  is being used. In  FIG. 6  like numbers have been used to indicate like parts to those described above. The tension control  100  is essentially the same as that shown in  FIGS. 1, 2 and 3  but the embodiment of  FIGS. 4 and 5  could equally well be used. The tension control  100  need not be re-described and thus only the differences will be discussed. 
         [0056]    The roll  202  mounted on the frame  200  may be a simple roll or may be a clutch roll as described above reference to clutch roll  32  and used to replace or supplement the clutch roll  32  on the applicator  10 . If used in conjunction with the clutch roll  32  the drag normally applied by the clutch roll  32  will be shared in any suitable manner between the two clutch rolls  32  and  202 . This is the preferred arrangement as it provides for better control of the tape than if it were an ordinary free-wheeling roll. It is preferred that the applicator  10  be left substantially in tacked with the minimum number of changes and thus the clutch roll  32  normally will not be replaced. 
         [0057]    In the arrangement illustrated in  FIG. 6  an entry roll  104  has been included on the applicator portion  102  so the tape  18  leaving the roll  202  on the modified tape path  204  passes around the entry roll  104  and then to the clutch roll  32  on the applicator  10  for application by the applicator  10  to the case or carton  11 . 
         [0058]    Having described the invention, modifications will be evident to those skilled in the art without departing from the scope of the invention as defined in the appended claims.