Abstract:
A swivel mount is configured for use with a tamp pad for a label applicator of the type for receiving a label at a first retracted position and applying the label to an object at a second, extended position. The mount includes a mounting block for fastening to the tamp pad. The mounting block has a bore therein having an inner, open cross-sectional region and a retaining region. A knuckle fitting is received within the bore and is engageable with the retaining region. The knuckle fitting has a largest cross-sectional area that is larger than the open cross-sectional area of the retaining region such that a portion of the knuckle fitting is retained within the bore. A spring is positioned to provide a force against the knuckle fitting against the retaining region. The mount permits movement of the tamp pad from an orientation perpendicular to a direction of movement between the retracted and extended positions to an orientation inclined relative to the direction of movement.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a label applicator. More particularly, the present invention pertains to a spring mount for a label applicator tamp pad. 
     Automated label applicators or label machines are well known in the art. A typical machine feeds a continuous web of label material (which web material includes a carrier or liner and a series of discrete labels adhered to the liner at intervals along the liner), removes the labels from the liner and applies the labels to the objects. In many such machines, the label is also printed by the device, prior to separation from the liner and application to the objects. 
     Known label machines include, generally, a supply roll on which the web is wound. The web is fed from the supply roll around a plurality of rollers and enters a printing head. In the printing head, indicia are printed on to the individual labels. The web exits the print head and the labels are separated from the liner and are urged into contact with a tamp pad. 
     The tamp pad is, typically, a vacuum assisted assembly that holds the individual labels and moves the labels into contact with the objects onto which they are adhered. Tamp pads are typically designed to apply a predetermined or desired force upon application of the label to the object. The force used to apply the label can be varied depending upon the object. For example, while a relatively larger force can be used to apply a label to a heavy gauge shipping carton, a much lesser force must be used when applying a label to, for example, a bakery carton. 
     In operation, the label is separated from the liner and is held on the tamp pad. The label remains on the pad until the target object is in line with the pad. A tamp cylinder then extends to move the tamp pad into contact with the object surface to apply the label to the surface. At the completion of the extension stroke, the cylinder returns the pad to the home or rest position at which time a subsequent label can be fed onto the tamp pad. In many known arrangements, the tamp pad is rigidly mounted to the extendable cylinder rod. 
     Tamp pads are configured such that a label is transferred onto the pad after it is separated from the liner with the non-adhesive side of the label contacting an impact plate (on the front side of the pad). The label is held on the plate and the tamp pad is extended toward the product surface for application of the label. In a typical arrangement, a vacuum is used to secure the label to the impact plate. Typical impact pads are formed from a low friction material having a plurality of vacuum openings formed therein. Vacuum channels formed in the rear of the plate permit the transfer of vacuum to the front surface of the impact plate to secure the label to the plate. 
     In that it is desirable to transfer the label and apply the label to the product surface at a relatively high rate of speed, the transfer process inherently controls the throughput of the label machine. However, the objects to which the labels are applied may not necessarily be properly oriented on the object line path. That is, the cartons may not all lie straight on the machine line such that the plane of the panel onto which the label is applied is perpendicular to the direction of extension of the cylinder. As such, labels can be misapplied or less than fully applied to the carton panel. 
     One known arrangement to accommodate a slightly askew carton includes a tamp pad that is mounted to a mounting plate by a plurality of corner mounted springs and shoulder bolts. While such an arrangement serves to accommodate carton skew to a point, it requires a complex arrangement of bolts and springs, as well as a complex arrangement for the traverse of vacuum tubes and the like to provide the necessary structural vacuum connections to the tamp head. Moreover, with this type of mount, as the angle at which the pad contacts the carton increases, the pad “rotates” away from a plane perpendicular to the direction of extension of the cylinder. 
     When the angle increases too greatly, the edges of the pad around the bolt openings can bind on the bolts. In such an event, the pad can become “stuck” on the bolts at an angle. This, of course, would require that machine operation be halted so that the pad can be readjusted to the desired, perpendicular orientation. Given that the label applying operation is a relatively high speed operation, this could have a substantial adverse impact to machine and/or line operations. 
     Accordingly, there exists a need for a tamp pad mount that accommodates the skew of a carton panel or other object onto which the label is applied. Desirably, such a mount is biased to a perpendicular orientation, and is readily moved from the perpendicular position to properly apply the label to the panel. More desirably, such a mount is simple in design, prevents binding at an undesirable angle, and can be fitted onto existing label applicator machines. 
     BRIEF SUMMARY OF THE INVENTION 
     A swivel mount is configured for mounting a tamp pad to a label applicator of the type for receiving a label at a first retracted position and applying the label to an object at a second, extended position. The mount permits the application of a label to an object, such as a carton panel and accommodates the skew of the carton panel or other object. Such a mount is biased to a perpendicular orientation, and is readily moved from the perpendicular position to properly apply the label to the panel. 
     The mount includes a mounting block for fastening to the tamp pad. The mounting block has a bore therein having an inner, open cross-sectional region and defines a retaining region therein. In a current embodiment, the retaining region is configured as a collar. 
     A knuckle fitting is received within the bore and engages or seats in the retaining region. The knuckle fitting has an increasing cross-sectional area that is, at its largest point, larger than the open cross-sectional area of the retaining region. In this manner only a portion of the knuckle fitting extends beyond the collar, while another portion of the knuckle fitting is maintained within the bore. 
     In a present embodiment, the knuckle has tapered side walls and the collar has mating side walls. A present taper angle is about 20 degrees. In this arrangement, the knuckle fitting has a frusto-pyramidal shape, and preferably a square frusto-pyramidal shape. The corners defined by the frusto-square pyramidal shape can be rounded. 
     A spring is positioned to provide a force against the knuckle fitting at an end of the second portion. The spring seats the knuckle fitting within the collar. Preferably, the spring is centrally disposed relative to a longitudinal axis or plane through the mount. 
     To maintain the spring and knuckle fitting within the mounting block, a cover can be positioned on the mounting block extending over the bore and the spring. The cover further assures that the spring force acts on the knuckle fitting maintaining the fitting centered within the block. 
     A present knuckle fitting is formed from an aluminum alloy, such as alloy 7075-T6 with a hardcoat anodized finish. Such a material provides the strength, durability and wear resistance needed for such a part in a high cycle environment. 
     The present mount permits movement of the tamp pad from an orientation perpendicular to a direction of movement between the retracted and extended positions to an orientation inclined relative to the direction of movement. Moreover, it permits such movements, and facilitates return to the perpendicular orientation, in a relatively light weight and efficient, yet simple design. Further, the present mount has been found to overcome many of the problems of known designs, other than complexity, such as pad binding and sticking. 
     These and other features and advantages of the present invention will be apparent from the following detailed description, in conjunction with the appended claims. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     The benefits and advantages of the present invention will become more readily apparent to those of ordinary skill in the relevant art after reviewing the following detailed description and accompanying drawings, wherein: 
     FIG. 1 is a front view of an exemplary label printer applicator having a spring mounted tamp pad embodying the principles of the present invention; 
     FIG. 2 is an enlarged, partial front view of the applicator showing the present spring mount as used in mounting a tamp pad to the applicator; 
     FIG. 3 is a schematic illustration of the tamp pad cylinder and mount showing the tamp pad slightly skewed for applying a label to a non-perpendicular panel; 
     FIG. 4 is a partial cross-sectional view of the tamp pad cylinder and mount arrangement, the tamp pad again being shown slightly askew as it would apply a label to a non-perpendicular panel; 
     FIG. 5 is an exploded view of the spring mount; and 
     FIG. 6 is an exploded view of an exemplary tamp pad showing the impact plate and the rear mounting plate, and the mounting of the mounting block thereto. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     While the present invention is susceptible of embodiment in various forms, there is shown in the drawings and will hereinafter be described a presently preferred embodiment with the understanding that the present disclosure is to be considered an exemplification of the invention and is not intended to limit the invention to the specific embodiment illustrated. 
     It should be further understood that the title of this section of this specification, namely, “Detailed Description Of The Invention”, relates to a requirement of the United States Patent Office, and does not imply, nor should be inferred to limit the subject matter disclosed herein. 
     Referring now to the figures and in particular, to FIG. 1 there is shown generally an exemplary automatic label printer applicator  10  or label machine  10 . The machine  10  includes a frame or stand  12  and is positioned above objects (not shown) onto which labels are placed. The frame  12  has mounted thereto a supply or unwind roll  14 , a print head  16 , a tamp pad assembly  18  and a take-up or rewind roll  20 . The exemplary label printer applicator  10  is commercially available from ITW Diagraph of St. Charles, Mo. as product model ALP/4500. Such a machine  10  is more fully disclosed in copending to Dods U.S. Ser. No. 10/213,654, filed Aug. 6, 2002, and entitled “Label Printer Applicator Unwind Sensor”, which patent application is commonly assigned with the present application and is incorporated herein by reference. 
     A web, indicated generally at W (which includes a backing or liner strip N on which discrete labels are adhered), is fed from the supply roll  14  and traverses through the print head  16 , in which indicia are printed on the individual labels. The labels are then separated from the web W by a separating blade  22  and are transferred to a tamp pad  24  on the tamp pad assembly  18 . A tamp pad cylinder  26  includes a reciprocating cylinder rod  28  (having the tamp pad  24  mounted thereto) that extends to apply the label to the surface of the object. The liner N, after the labels have been removed, is then wound onto the take-up or rewind roll  20 . The operation of the label machine  10  is controlled by a controller  30  mounted local to (or on) the machine  10 . 
     Referring now to FIGS. 2-4, the tamp pad  24  is part of the overall tamp pad assembly  18 . In a present embodiment, the cylinder  26  is a pneumatic cylinder. The tamp pad  24  is mounted to the cylinder rod  28  by a spring mount  32  and moves with extension and retraction of the cylinder rod  28  between the label applying or extended position and a label receiving or home position. These positions are the positions at which the label is applied to the product surface and the position at which the label is moved onto the tamp pad after separation from the liner N. 
     In a present arrangement, a dual action cylinder  26  is used. That is, compressed air (or a like compressed gas) is applied to one side of a piston in the cylinder  26  to extend the cylinder rod  28  and is applied to an opposing side of the piston to retract the rod  28 . Compressed air supply lines extend from a compressed air source (not shown) to inlets  34 ,  36  at opposing sides of the cylinder  26  to move the rod  28  between the extended and home positions. 
     A present tamp pad  24  is configured to allow changing label sizes quickly and to allow use of a single pad with multiple size labels. This flexible design is more fully disclosed in the aforementioned U.S. patent application Ser. No. 10/213,654. The tamp pad  24  includes a rear mounting plate  38  onto which a vacuum inlet, such as the illustrated vacuum elbow fitting  40  is mounted. 
     An impact plate  42  is mounted to the rear mounting plate  38 . The impact plate  42  is that plate onto which the label is transferred and is carried to the object surface for adhering to the object. The impact plate  42  is mounted to the rear mounting plate  38  by a plurality of fasteners, such as the illustrated flat head machine screws  44 . The vacuum fitting  40  in the mounting plate  38  provides communication of vacuum from the vacuum source to channels  46  in the rear side of the impact plate  42 . The impact plate  42  has through-plate openings  48  from the channels  46  that open into the front surface of the plate  42  for securing the label to the plate  42 . 
     The tamp pad  24  is mounted to the cylinder rod  28  by the spring mount  32 . The spring mount  32  is rigidly fastened to the rear mounting plate  38 . The mount  32  provides a simple, biased movable connection of the tamp pad  24  to the cylinder rod  28 . Referring to FIGS. 3 and 4, a present spring mount  32  includes a mounting block  50 , a knuckle connector fitting  52 , a biasing element  54 , such as the illustrated coil spring, and a block cover  56 . The mounting block  50  has a cavity  58  formed therein for receiving the knuckle fitting  52 . A collar  60  extends upwardly from the block  50  about the cavity  58 . A bore  62 , which is contiguous with the cavity  58 , extends from the cavity  58  through the collar  60 . 
     The interior surfaces, indicated generally at  64 , that define the collar  60 , at the bore  62 , are formed as upwardly, inwardly tapered surfaces and the knuckle fitting  52  has mating tapered outer surfaces, indicated generally at  66 , to maintain the fitting  52  centered when it is seated within the bore  62  at the collar  60 . In a present embodiment, the cavity  58 , bore  60 , collar  62  and knuckle fitting  52  all have a generally square cross-sectional profile to further provide mating surfaces and centering of the knuckle fitting  52  within the mounting block  50  and bore  62 . As best seen in FIGS. 4 and 5, the knuckle fitting  52  has a generally obelisk-like (frusto-square pyramidal) shape, having rounded corners  68 . The collar mating surfaces  64  define a like obelisk-like (frusto-square pyramidal) shape. 
     A lip  70  extends downwardly from the knuckle fitting  52  (about the bore  62 ), and the spring  54  is positioned about the lip  70  to retain the spring  54  in place. Preferably, the spring  54  is centrally disposed in the bore  60  relative to a longitudinal axis A 32  through the mount  32 . The cover  56  is fastened to the mounting block  50  by fasteners  71  to secure the spring  54  about the knuckle fitting lip  70  and to secure the knuckle fitting  52  within the block  50 . In this manner, the spring mount  32  is a fully contained, readily installed one-piece fitting. 
     The terms upwardly and downwardly are used in reference to the direction in which various components and surfaces extend for purposes of description only. Those skilled in the art will appreciate from a study of the present description and figures that the present applicator  10  is a vertically operating applicator  10 . That is, the tamp pad  24  and cylinder  26  operate in a vertical, up-and-down movement to apply labels to objects. The present mount  32  can, however, be effectively used in horizontally or other oriented applicators in which the tamp pad, cylinder and associated components would operate in a horizontal plane. Such a horizontal orientation is within the scope and spirit of the present invention. 
     Referring to FIG. 3, to attach the spring mount  32  to the cylinder rod  28 , the end of the rod  28  has an externally threaded surface and the interior of the knuckle fitting  52  has a mating internal thread. Thus, to attach the fitting  52  (as captured within the mounting block  50 ) to the rod  28 , the fitting  52  is merely threaded onto the rod  28 . To secure the knuckle fitting  52  in place on the rod  28 , i.e., to prevent the knuckle  52  from loosening or tightening by rotating about the threads, a jam nut  72  can be turned and tightened down onto the knuckle fitting  52  at the knuckle fitting  52 -rod  28  interface. Alternately, as will be recognized by those skilled in the art, various other methods and devices can be used to secure the knuckle fitting  52  in place on the rod  28 , such as thread locking tape, pins and the like, which other methods and devices are within the scope and spirit of the present invention. 
     The mounting block  50  is fastened to the tamp pad rear mounting plate  38  by a plurality of fasteners  74  that insert through the mounting block  50  and thread into mounting openings  76  in the plate  38 . The cover  56  has aligned holes  78  to permit passing the fasteners  74  through the cover  56  and into the plate  38 . 
     As will be appreciated by those skilled in the art from a study of the figures and above description, the present spring mount  32  accommodates the application of labels onto skewed surfaces. When operating, the tamp pad  24  is oriented perpendicular to the direction of extension E of the cylinder rod  28 . In the event that a panel (onto which the label is applied) is skewed, an edge or corner  84  of the tamp pad  24  will contact the panel and the tamp pad  24  will move, e.g., swivel, to orient the pad  24  parallel to the surface to properly apply the label. The spring  54  urging the knuckle tapered surfaces  66  against the collar inner tapered surfaces  64  permits the pad  24  to swivel and, advantageously returns the tamp pad  24  to the perpendicular orientation once the pad  24  moves out of contact with the surface. 
     In a current embodiment, the taper angle α of the knuckle fitting surfaces  66  is about 20 degrees. The taper angle β of the collar inner surfaces  64  is likewise about 20 degrees. These matching taper angles α and β have been shown to function quite well to permit the pad  24  to swivel to essentially any position to accommodate carton skew, while at the same time to return the tamp pad  24  to the perpendicular orientation after carton contact. As will be appreciated to those skilled in the art, the present design overcomes the binding problem associated with known corner bolt mounting arrangements in that there is no bolt on which to bind or hang up the mount. 
     It will also be appreciated that the present spring mount  32  configuration permits the tamp pad  24  to torque about the axis that defines the direction of extension E (which is also coincident with the mount axis A 32 ), and return back to a home position for receiving a subsequent label. That is, the knuckle fitting  52  will allow the pad  24  to move slightly in a plane perpendicular to the axis A 32  and will return the pad to the home position by engagement of the knuckle fitting surfaces  66  with the collar surfaces  64  that urge the knuckle  52  to squarely “seat” within the collar  62 . 
     In the current embodiment, it has been found that the material selection for the knuckle fitting  52 , while not critical, must take into consideration the magnitude and intensity of cycling to which the mount  32  is expected to be subjected. That is, because of the high operating line speeds and the variations in the angle of carton panels, the mount  32  must be sufficiently strong to overcome rigorous operating conditions. It has been found that an aluminum alloy, specifically, Alloy 7075-T6, commercially available from the TENNALUM® division of Kaiser Aluminum, of Jackson, Tenn., is suitable for use for manufacture of the knuckle fitting  52  of the present mount  32 . It has also been found to be advantageous to use a hardcoat anodizing on the knuckle fitting  52  to improve wear resistance and to increase life, as well as to facilitate movement of the fitting  52  within the mounting block  50  during operating conditions. 
     Other materials are also contemplated for use in the present spring mount  32 . For example, metals such as hardened steel and various plastic materials, such as a self-lubricating plastic, may also be suitable for use in the present mount  32 , which other materials are within the scope and spirit of the present invention. 
     The simple design of the present spring mount  32  permits retrofitting existing label applicators to accommodate the mount  32 . In that a minimal number of parts have been added to known tamp pad mounting arrangements, the added weight, if any, of the present mount  32  will have minimal, if any, adverse impact on overall applicator machine  10  operations. 
     All patents referred to herein, are hereby incorporated herein by reference, whether or not specifically done so within the text of this disclosure. 
     In the present disclosure, the words “a” or “an” are to be taken to include both the singular and the plural. Conversely, any reference to plural items shall, where appropriate, include the singular. 
     From the foregoing it will be observed that numerous modifications and variations can be effectuated without departing from the true spirit and scope of the novel concepts of the present invention. It is to be understood that no limitation with respect to the specific embodiments illustrated is intended or should be inferred. The disclosure is intended to cover all such modifications as fall within the scope of the invention.