Abstract:
A method for forming a top seal on a carton being conveyed along a processing path on a form, fill and seal packaging machine using a top sealer including opposing sealing jaws is provided. The carton includes top fin panels configured for sealing to one another to form a top seal. The method includes actuating a first control valve to provide communication between a first pressurized fluid source and a first port of an actuator for moving the actuator toward a first position. The actuator is operatively connected to the sealing jaws to move the sealing jaws in a clamping direction while moving toward the first position. A second control valve is actuated to inhibit fluid escape from the actuator through a second port of the actuator to inhibit movement of the sealing jaws in the clamping direction.

Description:
TECHNICAL FIELD 
     The present application relates generally to carton filling apparatus and more particularly to a carton top sealer apparatus and associated method. 
     BACKGROUND 
     Conventional paperboard cartons for liquid food products are commonly constructed from paperboard sheets coated with a film of a heat sealable, waterproof thermoplastic material such as polyethylene, polyvinyl chloride or polypropylene. When heated, this plastic film becomes tacky, so that sheets thus coated and heated can be sealed together by being squeezed tightly together. The coated sheets are initially cut into flat carton blanks. These blanks are subsequently folded into a generally rectangular open-ended configuration, then are closed at one end by forming a bottom end wall via folding and sealing bottom end closure panels which extend integrally from the four side walls of the carton blank. The cartons can then be filled and sealed with a gabled or flat-folded top. 
     Automated carton filling apparatus are frequently used to automatically form, fill and seal cartons. Automated mechanical systems (e.g., a top sealer and a bottom sealer) are frequently utilized to fold and/or seal the tops and/or bottoms of the cartons. Due to the rates of speed of production, such systems can be noisy. Pneumatically driven systems have been proposed to reduce noise during operation. 
     SUMMARY 
     In an aspect, a method for forming a top seal on a carton being conveyed along a processing path on a form, fill and seal packaging machine using a top sealer including opposing sealing jaws is provided. The carton includes top fin panels configured for sealing to one another to form a top seal. The method includes actuating a first control valve to provide communication between a first pressurized fluid source and a first port of an actuator for moving the actuator toward a first position. The actuator is operatively connected to the sealing jaws to move the sealing jaws in a clamping direction while moving toward the first position. A second control valve is actuated to inhibit fluid escape from the actuator through a second port of the actuator to inhibit movement of the sealing jaws in the clamping direction. 
     In another aspect, in a carton filling apparatus, a system for forming a top seal on a carton being conveyed along a processing path of the carton filling apparatus is provided. The system includes a top sealer including opposing sealing jaws and control system including an actuator operatively connected to the sealing jaws for opening and closing the sealing jaws to receive and seal the carton. The control system further includes a first pressurized fluid source that delivers pressurized fluid to the actuator, a first control valve that controls delivery of pressurized fluid to the actuator from the first pressurized fluid source and a second control valve that controls escape of pressurized fluid from the actuator. The control system actuates the first control valve to provide communication between the first pressurized fluid source and a first port of the actuator for moving the actuator toward a first position. The actuator is operatively connected to the sealing jaws to move the sealing jaws in a clamping direction while moving toward the first position. The second control valve is actuated by the control system to inhibit fluid escape from the actuator through a second port of the actuator to inhibit movement of the sealing jaws in the clamping direction. 
     The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and the drawings, and from the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an embodiment of a carton filling apparatus; 
         FIG. 2  is a perspective view of an embodiment of a top sealer apparatus for use in the carton filling apparatus of  FIG. 1 ; 
         FIG. 3  is a side view of an embodiment of a top sealer apparatus similar to that of  FIG. 2  illustrating arm pivots; 
         FIG. 4  is a schematic illustration of an embodiment of a control system for use in controlling actuation of the top sealer of  FIG. 3 ; 
         FIG. 5A  is an embodiment of a process of controlling actuation of the top sealer of  FIG. 3 ; 
         FIG. 5B  is an embodiment of a timeline; 
         FIGS. 6A-6C  illustrate the control system of  FIG. 4  in various stages of use; and 
         FIG. 7  is a perspective view of an embodiment of a flow control device for use in the control system of  FIG. 4 . 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , a container filling apparatus  10  sometimes referred to as a form, fill and seal packaging machine includes a carton magazine  12  for storing flat carton blanks, a carton preassembly station  14  and a bottom forming and sealing station  16 . The apparatus  10  may also include air filtering features for filtering contaminants such as dust particles from regions of the apparatus through which the cartons travel. The apparatus  10  further includes a filling station  18  that is used to fill cartons subsequent to their preassembly at station  14  and bottom forming and sealing at station  16 . Top panels of the cartons are folded and sealed at a top sealing station  20 . 
       FIG. 2  shows an isolated view of a top sealer  22  embodiment. Top sealer  22  includes opposing sets  24  and  26  of arms  28  and  28 ′ with each arm including an upper arm  28   a  that is connected to a lower arm  28   b . Sealing jaw members  30  and  30 ′ are carried by the upper arms  28   a . The sealing jaws  30  of set  24  oppose the sealing jaws  30 ′ of set  26  so that, when closed or in a clamping position, the sealing jaws press against the carton  32  tops to tightly squeeze the cartons for sealing the carton flaps. 
     Referring to  FIG. 3 , arms  28 ,  28 ′ are pivotable about respective arm pivots  34  and  36 . Pivoting of the arms  28 ,  28 ′ about their respective pivots  34 ,  36  allow the arms to open and close to receive and seal cartons  32  as the cartons travel along a carton path. Arm  28 ,  28 ′ movement is controlled by a control system that includes an actuator (e.g., a linear or rotary actuator), in this example, a pneumatic, dual action cylinder  38 . Cylinder  38  includes an output rod  40  that is connected to a pair of rollers  42 ,  44  displaced horizontally (or radially) from the rod. The rollers  42 ,  44  are in contact with respective displacement members  46  and  48 , each having a rolling surface  50 ,  52  along which the rollers travel. The rollers  42 ,  44  and displacement members  46 ,  48  are used to convert movement of rod  40  in the direction of arrow  54  into pivoting movement of the arms  28 ,  28 ′ about pivot points  34 ,  36  as reflected by arrows  56 . Other coupling arrangements may be utilized. 
     As can be appreciated from  FIG. 3 , retraction (e.g., upward movement) of the cylinder rod  40  causes the rollers  42 ,  44  to travel along angled portions  58 ,  59  of the displacement members  46 ,  48 , which allows the lower arms  28   b  to travel toward each other (e.g., due to biasing member  62  such as a spring that biases ends of the lower arms  28   b  toward each other). In response, sealing jaws  30 ,  30 ′ move apart or open. Extension (e.g., downward movement) of the cylinder rod  40  forces the lower arms  28   b  away from one another, which causes the upper arms  28   a  and sealing jaws  30 ,  30 ′ to move toward one another in a clamping motion. Other arrangements are contemplated. For example, the displacement members  46 ,  48  may be shaped and arranged such that retraction of the cylinder rod  40  causes the upper arms  28   a  and sealing jaws  30 ,  30 ′ to move toward one another in a clamping motion and extension of the cylinder rod  40  causes the upper arms to move away from each other toward an open position. 
     Referring to  FIG. 4 , control system  60  includes a control valve circuit  62  for use in controlling extension and retraction of the cylinder  38 . Control system  60  includes a first pressurized fluid supply  64  capable of communicating with cylinder  38  through an extend port  66  and a second pressurized fluid supply  68  capable of communicating with the cylinder through a retract port  70 . Extend port  66  is in communication with an extend chamber  76  of the cylinder  38  (at one side of piston  71 ) and retract port  70  is in communication with a retract chamber  78  of the cylinder (at the opposite side of piston  71 ). First and second control valves  72  and  74  control delivery and escape of pressurized fluid to and from the cylinder  38 . A flow control valve  80  provides for restricted exhausting of pressurized fluid from extend chamber  76  through the extend port  66 . Flow control valve  80  includes a check valve allowing unrestricted fluid flow to the extend port  66  and a restriction (e.g., a needle valve) that can restrict fluid flow from the extend port. 
     Second control valve  74  is used in creating an air cushion to prevent the sealing jaws  30 ,  30 ′ from impacting at relatively high speed.  FIGS. 5A and 5B  illustrate an exemplary control process for use in controlling extension and retraction of the cylinder  38 . In the timeline  82  example of  FIG. 5B , one degree is approximately 2.5 milliseconds and the cycle repeats every 360 degrees. Approximate conveyor dwell is 0-130 degrees. However, the timing may change depending on, for example, processing and system requirements. 
     At step  84 , both of the first and second valves  72  and  74  are in their OFF positions as shown by  FIG. 6A . With the first and second valves  72 ,  74  in these positions, no pressurized fluid is delivered through the extend port  66  to the extend chamber  76  while the retract chamber  78  is pressurized (e.g., at 40 psi) using the second pressurized fluid supply  68  which fully retracts the rod  40  and sealing jaws  30  (i.e., the sealing jaws are in their open positions). At step  86 , the first control valve  72  is actuated (e.g., by a controller  75 ) and turned ON with the second control valve  74  remaining OFF as shown by  FIG. 6B . With the first control valve  72  in this position, pressurized fluid at a higher pressure than that delivered by the second pressurized fluid supply  68  is delivered by the first pressurized fluid supply  64  to port  66  into the extend chamber  76 . Because the cylinder  38  is allowed to exhaust through the retract port  70 , the rod  40  begins to extend. At approximately ten degrees after step  86 , the second control valve  74  is actuated and turned ON at step  88  as shown by  FIG. 6C . With the second control valve  74  ON, fluid can no longer escape from the retract chamber  78  through the retract port  70 . As the cylinder  38  extends, pressure builds in the retract chamber  78 . When the cylinder  38  extends an amount that is less than the fully extended position (e.g., about 90 percent of its stroke), the pressure in the retract chamber  78  increases to an amount about equal to the pressure in the extend chamber, causing the rod  40  to slow down substantially (in some embodiments, stop) extending prior to reaching its fully extended position. 
     Approximately ten degrees after step  88 , the second control valve  74  is actuated and turned OFF at step  90  as shown by  FIG. 6B . With the second control valve  74  OFF, trapped fluid in retract chamber  78  is again allowed to escape through the retract port  70 . Pressurized fluid continues flowing from the first pressurized fluid supply  64 , through the extend port  66  and into the extend chamber  76  causing the cylinder  38  to extend to its fully extended position which causes the sealing jaws  30  to move to their clamped position. The final movement of the sealing jaws  30  is slower than if movement of the sealing jaws were not slowed or stopped at step  88 , which reduces noise produced by the clamping of the sealing jaws. At step  92 , steady-state is reached with substantially no fluid in the retract chamber  78  and the extend chamber  76  fully pressurized. At step  92 , full squeezing force (e.g., about 2000 lbs) is applied to seal the carton top. At this step, the top sealer may also be used to cool the carton top. At step  94 , the first control valve  72  is actuated and turned OFF as shown by  FIG. 6A  so that pressure drops at a moderate rate due to the restriction of flow control valve  80 . Pressurized fluid is delivered from the second pressurized fluid supply  68  to the retract chamber  78  and the cylinder  38  retracts at moderate speed due to the restricted escape of fluid from the extend port  66 . 
     Referring now to  FIG. 7 , a manifold  100  is shown for providing the first control valve  72  and the second control valve  74  for multiple cylinders  38  (e.g., with each cylinder  38  dedicated to move a respective pair of arms  28  and  28 ′ as described above). A suitable exemplary manifold  100  is an eight station air manifold available from SMC Pneumatic, Inc. located at Indianapolis, Ind. 
     By providing control system  60 , relatively quiet machine  10  operation can be realized. In some embodiments, the carton filling apparatus  10  may operate at a noise level of less than about 80 dB, such as at about 78 dB. Noise level can be measured using a M-27 Noise Logging Dosimeter, available from Quest Technologies Inc., that is spaced horizontally from the apparatus  10  one meter and is placed one meter off of the ground with the apparatus  10  at its operating location. 
     A number of detailed embodiments have been described. Nevertheless, it will be understood that various modifications may be made. Accordingly, other embodiments are within the scope of the following claims.