Patent Publication Number: US-2007110896-A1

Title: Closure sealant dispenser

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
      This application is a divisional application of U.S. patent application Ser. No. 10/670,176 entitled “Closure Sealant Dispenser” by William W. Weil, et al., filed Sep. 23, 2003, which claims the benefit of and priority to U.S. Provisional Patent Application Ser. No. 60/412,988 by William W. Weil, et al., entitled “Can Sealant Dispenser” filed Sep. 23, 2002, the entire contents of which are hereby specifically incorporated by reference for all they disclose and teach. 
    
    
     BACKGROUND OF THE INVENTION  
      Sealant is often applied to closures such as can lids and bottle lids prior to joining the closures to the container body. The sealant, also known as “compound” within the industry, may be dispensed in liquid form on the closure. The dispensing technology is well developed for circular can closures.  
      Non-circular cans, such as rectangular, square, oval, or ham-shaped, pose a significant difficulty for application of the sealant. The need to precisely control the amount of sealant while processing the closure at a high rate of speed poses a high degree of difficulty for the machine designer. Maintenance of high-speed machines further dictates that machines must be designed to be as simple and easy to repair as possible.  
      The sealant should be dispensed in a controlled manner to limit any excess sealant material on the closure. Excess sealant, while not dangerous if in contact with foodstuffs, adds additional costs to the can and may be squeezed out of the intended location during the process of seaming the closure to the can. Given the large number of closures that may be processed, saving a small amount of sealant on each can closure can translate into substantial cost savings. The prior art includes machines for placing sealant onto circular closures. These machines generally have a sealant dispenser that dispenses the sealant material onto a spinning closure. The closures are presented to the sealant dispenser on a chuck that lifts the closure into place and rotates the closure underneath the sealant dispenser. Machines for dispensing sealant material onto circular closures are capable of running at very high speeds.  
      However, methods for placing sealant onto non-circular closures have been only marginally successful. One method is similar to pad printing wherein an applicator places the sealant material onto a non-circular can closure by pressing a sealant-dipped applicator onto the closure periphery surface. Such printing-type methods use a large amount of sealant and are not very accurate. These techniques are only used for small batch runs.  
      An additional method for placing sealant onto non-circular closures is to position the closure under a showerhead and flood the periphery of the closure with sealant. This method also uses large amounts of sealant, and is not very accurate. Additionally, the showerheads require constant cleaning and blocked holes can cause a gap in the sealant.  
      In another machine, a sealant dispenser is moved in and out along a radius with respect to the rotating axis of the closure. Such machines are a simple modification to the existing circular closure-processing machine. However, the mass of the sealant dispenser limits the speed at which the machine may operate. Such a system is shown in U.S. Pat. No. 6,391,387 issued to Rutledge, et al. on May 21, 2002 which is specifically incorporated herein by reference for all that it discloses and teaches.  
      It would therefore be advantageous to provide a high speed, highly accurate method and apparatus for dispensing sealant to irregularly shaped closures.  
     SUMMARY OF THE INVENTION  
      The present invention overcomes the disadvantages and limitations of the prior art by providing a system and method for applying sealant to closures by controlling the movement of the closure with respect to the stationary sealant dispenser in an accurate and high speed manner.  
      The present invention may therefore comprise a method of applying sealant to a non-circular closure comprising: loading the closure onto a chuck, the closure having a periphery about which the sealant is to be applied, the periphery defining a plane; positioning the chuck so that the closure is in alignment with a stationary sealant dispenser; rotating the chuck about an axis substantially perpendicular to the plane defined by the periphery and simultaneously translating the chuck in at least one linear axis within the plane such that the periphery of the closure is maintained in alignment with the sealant dispenser; dispensing the sealant about the periphery while the closure is simultaneously rotating and translating with respect to the sealant dispenser; and unloading the closure from the chuck.  
      The present invention may further comprise a closure sealant applicator machine for dispensing sealant to the periphery of non-circular closures comprising: a sealant dispenser substantially fixedly mounted to the sealant applicator machine; a chuck adapted to hold the closure in a plane; a rotational motor in rotational communication with the chuck, the chuck adapted to rotate along an axis substantially perpendicular to the plane; a translational mechanism adapted to linearly move the chuck along at least one axis within the plane; and a controller adapted to simultaneously rotate and translate the closure with respect to the sealant dispenser to maintain the periphery of the closure in alignment with the sealant dispenser while the sealant dispenser dispenses the sealant.  
      The present invention may further comprise a non-circular closure having sealant applied to the periphery manufactured by a method comprising: loading the closure onto a chuck, the closure having a periphery about which the sealant is to be applied, the periphery defining a plane; positioning the chuck so that the closure is substantially aligned with a stationary sealant dispenser; rotating the chuck about an axis substantially perpendicular to the plane and simultaneously translating the chuck in at least one direction within the plane such that the periphery of the closure is maintained in alignment with the sealant dispenser; dispensing the sealant about the periphery while the closure is simultaneously rotating and translating with respect to the sealant dispenser; and unloading the closure from the chuck.  
      The present invention may further comprise a non-circular closure having sealant applied to the periphery manufactured by a method comprising: loading the closure onto a chuck, the chuck being mounted onto a rotating turret, the closure having a periphery about which the sealant is to be applied, the periphery defining a plane; positioning the chuck so that the closure is substantially aligned with a sealant dispenser that is fixedly mounted on the rotating turret; rotating the chuck about an axis substantially normal to the plane and simultaneously moving the chuck in a radial direction on the turret such that the periphery of the closure is maintained in alignment with the sealant dispenser.  
      The present invention may further comprise a circular closure having sealant applied to the periphery manufactured by a method comprising: loading the closure onto a chuck, the chuck mounted onto a rotating turret, the closure having a periphery about which the sealant is to be applied, the periphery defining a plane; positioning the chuck so that the closure is substantially aligned with a sealant dispenser that is fixedly mounted on the rotating turret; rotating the chuck about an axis independent of any rotation derived by the rotation of the turret.  
      An advantage of various embodiments of the present invention is that sealant may be dispersed on a non-circular closure at very high speeds. Further, a minimum of sealant material is dispensed using various embodiments of the present invention due to the accurate and repeatable, yet high speed positioning of the non-circular closure with a substantially fixedly mounted sealant dispenser.  
      An additional advantage of the present invention is that standard motors, servomotors or all-in-one, fully integrated servomotor systems can be used that are mounted on rotating turrets that allow independent control of the rotating chuck from the rotational speed of the turret, which allows another degree of control over each dispensing station. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      In the drawings,  
       FIG. 1  is a schematic representation of various elements of one embodiment of the present invention.  
       FIG. 2  is an illustration of a one embodiment of the present invention wherein linear motion is driven by a cam.  
       FIG. 3  is an illustration of another embodiment of the present invention wherein linear motion is produced by a second servomotor.  
       FIG. 4  is an illustration of another embodiment of the present invention wherein a rotational motion is coupled by a spline and gears.  
       FIG. 5  is an illustration of another embodiment of the present invention wherein a rotational motor is mounted below a chuck and coupled with a flexible drive shaft.  
       FIG. 6  is an illustration of another embodiment of the present invention wherein a rotational motor is mounted below a chuck and coupled with a rigid drive shaft.  
       FIG. 7  is an illustration of another embodiment of the present invention wherein a rotational motor is mounted on a moving linear slide.  
       FIG. 8  is an illustration of another embodiment of the present invention wherein both the linear and rotational motors are fixed mounted.  
       FIGS. 9 and 10  are an illustration of another embodiment of the present invention wherein multiple rotational motors and liner sealant dispensers are mounted on a rotating turret and the linear motion is derived by the rotation of the turret around a cam.  
       FIGS. 11 and 12  are an illustration of another embodiment of a sealant applicator that is used for circular closures. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
       FIG. 1  illustrates a schematic representation of the various elements  100  of the present invention. A non-circular closure  102  is shown with a sealant dispenser  104  and the sealant  105  applied to the periphery of the closure  102 . The closure  102  is supported by a chuck  106  that may hold the closure  102  mechanically, magnetically, with the aid of vacuum or any way desired by the user. The chuck  106  moves with a rotary motion  108  and an in/out linear motion  110  to position the closure  102  under the sealant dispenser  104  to apply the sealant  105 . An optional second linear axis of motion  112  may be used to position the closure  102 . A vertical motion  114  is used to lift the closure  102  into position.  
      The sealant  105  is to be dispensed around the outer periphery of the closure  102 . The distance  101  and the angle of presentation  103  between the closure  102  and the sealant dispenser  104  remain the same during application of the sealant. In some cases, the sealant may form a bead 1 mm wide and be placed under a curled edge of the closure  102 . In such situations, the positioning of the closure  102  under and in alignment with the sealant dispenser  104  may need to be precise within 0.1 mm. In general, the more precisely the sealant may be applied, the less sealant is necessary to produce a seal when the closure  102  is subsequently sealed on an enclosure such as a can lid or bottle lid. Of course, there is a practical limit to the amount of sealant that needs to be present to seal the can.  
      In the various embodiments of the present invention, the sealant dispenser  104  is maintained in a substantially fixed position while the closure  102  is rotated with respect to the sealant dispenser  104 . In order to move in a path so that the sealant may follow the periphery  107  of the closure  102 , the chuck  106  is positioned underneath and in alignment with the sealant dispenser  104 . The chuck is simultaneously rotated and moved in an in/out linear motion  110  in a plane defined by the periphery  107  of closure  102 . In some cases, a second horizontal axis positioning system may also be used, which is represented by motion  112 .  
      The closure  102  may be presented to the processing machine using various conveying technologies. The up/down motion  114  may be used to lift closure  102  into position under the sealant dispenser  104 . After processing, the motion  114  may lower the chuck  106  so that the closure  102  may be removed from the apparatus and a second closure may be placed in position under the sealant dispenser  104  for processing.  
       FIG. 2  illustrates a schematic representation of an embodiment  200  of the present invention. A chuck  202  is positioned under and in alignment with a sealant dispenser  204 . A fixedly mounted servomotor  206  is coupled to the chuck  202  with a flexible drive shaft  208 . A cam  210  is driven by the servomotor  206  and produces a linear motion  214  in a single direction along an axis in the plane of chuck  202  as a result of the cam followers  212  being mechanically coupled to chuck  202 . The rotation of the chuck  216  together with the cam motion  214  causes the edge or periphery  207  of a closure  203  to remain directly under, and in alignment with, the sealant dispenser  204 . The flexible shaft  208  also makes possible the vertical motion  218  used to load and unload closures  203  from the apparatus.  
      The present embodiment  200  has a minimal amount of mass that needs to be translated and rotated during the sealant application sequence. The servomotor  206  may be fixedly mounted to a machine frame or the like. Only the carriage and various lighter weight components need to be rotated and/or translated during a dispensing procedure although an entire servo system can be moved, if desired. For example, a fully integrated servomotor system that includes a motor, a controller for controlling the speed of the motor, an amplifier and a shaft encoder, which is a feedback device, that provides information regarding the position of the shaft, can be moved in the direction of linear motion  110  or up and down in the direction of motion  114 , or any direction including motion  112 . Certain advantages can be obtained by using such an integrated servomotor system, as set forth below. The servomotor  206  may be fixedly mounted such that the weight of the motor does not have to be translated back and forth.  
      In high speed machinery, translation of large amounts of mass, such as a servomotor that may weigh a few pounds, can limit the speed at which a machine may be able to perform. By mounting the servomotor  206  off the moving carriage, the amount of mass may be reduced from several pounds to several ounces. The decreased mass means less wear and tear on the machine, less vibration, less power required, and increased speeds. Fully integrated servomotor systems, however, are relatively light weight and do not have the disadvantages of previous servo systems, as set forth below.  
      The cam  210  provides a mechanical mechanism to generate the linear motion  214 . The cam  210  has the advantage that the relationship between the linear motion  214  and rotational motion  216  is fixed, rigid, and ultimately reliable. In other embodiments where the linear motion  214  may be decoupled from the rotational motion  216 , the relationship between the two motions can be maintained by a computerized controller or by other techniques known in the art. A disadvantage to the cam  210  is that the changeover from one type of closure to a second type of closure may require a mechanical replacement of the cam  210 . Changes to such a system may be time consuming, while simple reprogramming of a computerized controller is all that is required for computerized servo systems.  
       FIG. 3  illustrates an embodiment  300  of the present invention wherein the linear motion is produced by a second servomotor  310 . A chuck  302  is positioned underneath a sealant dispenser  304 . A rotational servomotor  306  rotates the chuck  302  using a flexible drive shaft  308 . A second servomotor  310 , using a belt system  312  and carriage  314 , is used to move the chuck  302  in a linear motion  316 . The vertical motion  320  of the chuck is used to load and unload the closure on the chuck  302 .  
      Embodiment  300  provides another mechanism in which the servomotor  306  may be fixedly mounted so that the mass of the servomotor  306  is not carried on the carriage  314 . By minimizing the amount of mass in motion, the speed and reliability of the overall machine may be maximized. The rotational servomotor  306  and the linear servomotor  310  may be synchronized by a controller  309 . The synchronization may be programmable and easily adjustable. Methods and devices for performing synchronization are known in the art. Further, the programmability allows changeover from one size or shape of a closure to another size or shape with a minimum of mechanical changes. Further, the adjustment of the motion profile of the chuck  302  may be made with software rather than by changing mechanical components, such as a cam profile.  
      The position of the rotational servomotor  306  may be in any position such that the servomotor  306  and the chuck  302  are in communication by the flexible drive shaft  308 . Due to the flexibility of the drive shaft  308 , the machine designer may place the servomotor  306  as dictated by machine design concerns such as the available framework for mounting the motor  306 , proximity to control systems, or other requirements. The orientation of the servomotor  306  may be horizontal, vertical, or any other position.  
      In other embodiments, the servomotor  310 , belt system  312 , and carriage  314  may be replaced by other mechanisms known in the art for translating a carriage. For example, a linear servomotor may replace the motor  310 , belt system  312 , and carriage  314 . In other embodiments, a carriage  314  may be propelled by a lead screw attached to a motor  310 . In still other embodiments, the belt system  312  may be a toothed belt, an o-ring type belt, chain, or other endless, flexible medium. Those skilled in the art of machine design may create other embodiments using different linear motion mechanisms while remaining within the scope and intent of the present invention.  
       FIG. 4  illustrates another embodiment  400  of a sealant applicator. A chuck  402  is positioned underneath and aligned with a fixedly mounted sealant dispenser  404 . A rotational servomotor  406  is connected to the chuck  402  through a shaft  420 , spline  410  and gears  408 . A second servomotor  412  is connected through a belt system  414  to a carriage  416  to produce a linear motion  418  of the chuck  402 .  
      Embodiment  400  differs from embodiment  300  in that the connection of the rotational motor  406  to the chuck  402  is through a spline  410  and gears  408 . The spline  410  allows the motor  406  to be fixedly mounted while the carriage  416  is moved in the direction  418 . The rotation of the shaft  420  may still occur while the linear distance between the motor  406  and carriage  416  changes during the application of the sealant material.  
       FIG. 5  illustrates yet another embodiment  500  of a sealant applicator. A chuck  502  is positioned underneath and aligned with a sealant dispenser  504 . A rotational servomotor  506  is connected to the chuck  502  with a flexible drive shaft  508  and an optional spline  510 . A linear motion device  512  is connected to a servo  507 , which is in turn connected to a controller  509 , that function together to move the chuck  502  horizontally underneath the dispenser  504 . A second position  514  of the chuck  502  is also shown.  
      The embodiment  500  illustrates the mounting of the rotational servomotor in a vertical orientation and the coupling of the rotational servomotor to the chuck  502  with a flexible drive shaft  508 . In some cases, a spline  510  may be needed to account for the changing distance between the fixed mounted motor  506  and the chuck  502 . In other cases, the flexible drive shaft  508  may be mounted in such a manner that a spline  510  is not necessary.  
      The spline  510  may be necessary to allow the chuck  502  to move in a vertical motion to present the closure to the sealant dispenser  504 . In other cases, the sealant dispenser  504  may be adapted to move vertically in lieu of the vertical motion of the chuck  502 . In such an embodiment, the sealant dispenser  504  may be restricted to moving vertically and not in the plane of motion perpendicular to the axis of rotation of the chuck  502 .  
      The linear motion device  512  may be a linear motor, lead screw driven carriage, belt driven carriage, or other device known in the art to move the chuck  502  back and forth in a linear motion, or may be connected to servo  507 , which is controlled by controller  509 .  
       FIG. 6  illustrates another embodiment  600  of a sealant applicator. A chuck  602  is positioned underneath and in alignment with a sealant dispenser  604 . A rotational servomotor  606  is connected to the chuck  602  through a rigid drive shaft  608 , a spline  610 , and universal joints  612 . The chuck  602  is moved side to side by a linear motion device  614 , or by servo  618  which is controlled by controller  620 . The chuck  602  is also shown in a second position  616 .  
      The embodiment  600  differs from embodiment  500  in that a rigid drive shaft  608  is used instead of a flexible drive shaft  508  of embodiment  500 . The rigid drive shaft  608  may have higher load carrying capability or better repeatability than a flexible drive shaft in some cases.  
      The universal joints  612  may be yoke-type universal joints, or may be any of various forms of couplers so that the drive shaft  608  may be coupled to the motor  606  and transmit rotational force during a change in axis. Such couplers include pliable rubber couplers, constant velocity joints, or any other such coupler.  
       FIG. 7  illustrates another embodiment  700  of a sealant applicator. A chuck  702  is positioned underneath a sealant dispenser  704 . A rotational servomotor or fully integrated servomotor  706  is connected to the chuck  702  through a rigid drive shaft  710 . An integrated servomotor may comprise a servomotor that incorporates, into one integral package, additional parts, other than the motor and feedback device of a servomechanism, such as an amplifier, controller and/or a shaft encoder. The rotational servomotor  706  is moved side to side by a linear motion device  706 , or by servo  712  that is controlled by controller  714 . The linear motion device  708  may be a system of belts and pulleys, a lead screw driven stage, or any other linear motion device.  
      In the present embodiment, the motor/servomotor/integrated servomotor  706  is moved back and forth and contributes to the mass moved by the linear motion device  708 . While this mass can be more than some other embodiments, the mass of the sealant dispenser  704  as well as the related connectors and hoses may be more than the mass and related encumbrances of the motor  706 .  
       FIG. 8  illustrates yet another embodiment  800  of a sealant applicator. A chuck  802  is positioned underneath a sealant dispenser  804 . A fixedly mounted rotational servomotor  806  and a fixedly mounted linear servomotor  808  control the position of the chuck  802 . The rotational motion of the chuck  802  is transmitted through a belt  810  to the carriage  812 . The carriage  812  moves linearly and is controlled by the linear servomotor  808 . For the chuck  802  to rotate without linear motion, the rotational servomotor  806  is turned. For the chuck  802  to move linearly without rotational motion, both the rotational servomotor  806  and the linear servomotor  808  must rotate at the same time. The embodiment  800  has the advantage that the moving mass of the mechanism is minimal, however, there is an additional complexity in synchronizing the motion of the motors.  
       FIGS. 9 and 10  are a schematic representation of another embodiment  900  of a sealant applicator. Each chuck  902  is positioned under and aligned with a fixedly mounted sealant dispenser  904 . Servomotors  906  may comprise standard motors with remotely located controllers, or fully integrated servomotors that include the controller, amplifier, shaft encoder and the motor. In fact, each of the embodiments disclosed herein may use standard motors, servomotors or fully integrated servomotors, as desired. Each motor/integrated servomotor  906  is directly connected to a chuck  902 . The motors/integrated servomotors  906  are mounted on a turret  907 . The turret  907  is rotated around two cams  905 ,  908 . Rotation around the cam  905  produces a linear motion  914  along the radius of the turret  907 . The rotation of the chuck  916  coupled with the cam motion  914  maintains the periphery of a closure directly under and aligned with the sealant dispenser  904 . Rotating the turret around cam  908  lifts the motors and chucks which produces the vertical motion  918  that is used to load and unload closures from the sealant applicator  900 . The linear motion produced by cam  905  may also comprise system of belts and pulleys, a lead screw driven stage, servomotor, or any other linear motion device. Those skilled in the art of machine design may create other embodiments using different linear motion mechanisms while remaining within the scope and intent of the present invention.  
      Embodiment  900  can have single or multiple lining stations. Each chuck  902  has its own servomotor  906  making chuck rotation and velocity independent of the other chucks during the loading, unloading and sealant application sequence. The servomotor  906  may be a self-contained, fully integrated servomotor, or just the motor, as set forth above.  
      The cam  905  provides a mechanism to generate the linear motion  914 . The cam  905  has the advantage that the linear motion  914  can be distributed over a greater distance by increasing the radius of the turret. This can reduce the forces necessary to generate the motion  914  which ultimately makes the sealant applicator  900  more reliable. Since the linear motion  914  is decoupled from the rotational motion  916 , the relationship between the two motions must be maintained by a computerized controller, or by other techniques known in the art. A disadvantage associated with the use of cam  905  is that the changeover from one type of closure to a second type of closure may require a mechanical replacement of the cam  905 . Such a changeover may be time consuming. A computerized controller for controlling the motion can be used so that simple reprogramming of the controller produces the desired motion. The use of multiple chucks results in less vibration, less wear and tear on the sealant applicator  900 , and increased production speeds.  
       FIGS. 11 and 12  illustrate another embodiment  1000  of a sealant applicator that is used for circular closures. As shown in  FIG. 12 , chucks  1002  are positioned under and aligned with a sealant dispenser  1004 . Multiple servomotors  1006  are mechanically coupled to chucks  1002 . Servomotors  1006  can comprise fully integrated servomotors, or standard motors that have controllers and/or other apparatus not located directly on the motor. The motors/integrated servomotors  1006  are connected to a turret  1007 . Rotation of the turret  1007  around cam  1008  lifts the motors/integrated servomotors  1006  and chucks  1002  which provides the vertical motion  1018  used to load and unload closures from the sealant applicator  1000 .  
      Embodiment  1000  may have single or multiple lining stations. Each chuck  1002  has its own motor or fully integrated servomotor  1006  such that the chuck rotation and velocity are independent of the rotation of the turret and of the other chucks, during the loading, unloading and sealant application sequence. The motors  1006  may be fully integrated servomotors or standard servomotors, as indicated above, that can be independently controlled from each of the other motors/integrated servomotors.  
      Hence, various embodiments disclosed herein function to minimize the moving mass during dispensing of sealant materials to closures. This is accomplished by capturing the closure on a chuck that is translated and rotated beneath a fixed mounted sealant dispenser. A fixedly mounted motor in various embodiments is coupled to a rotating chuck through various mechanisms.  
      Another advantage of the various embodiments disclosed herein is that the constantly changing position of the closure during the application of the sealant maintains a constant volume of sealant along the periphery of the closure. Unlike the prior art, the embodiments disclosed herein maintain the distance and angle of presentation between the sealant dispenser and the closure which further aids in maintaining constant volume of sealant dispensed along the periphery. Further, various embodiments disclosed herein provide improved liners by permitting the chuck to be independently controlled during the loading, unloading, and application of the sealant, while the chuck and sealant applicator are rotated on a turret.  
      The foregoing description of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and other modifications and variations may be possible in light of the above teachings. The embodiment was chosen and described in order to best explain the principles of the invention and its practical application to thereby enable others skilled in the art to best utilize the invention in various embodiments and various modifications as are suited to the particular use contemplated. It is intended that the appended claims be construed to include other alternative embodiments of the invention except insofar as limited by the prior art.