Abstract:
An apparatus for effecting closure of an open end of a carton blank by placing portions of the carton blank into overlying relationship to one another is provided. The apparatus includes a cam that rotates about an axis of rotation and a cam lever that is operatively connected to the cam. The cam lever is used to convert rotating motion of the cam into linear motion to define a first stroke distance. A pressure pad is mounted for movement toward and away from the portions of the carton blank. The pressure pad is capable of being moved in response to input provided by the cam to define a second stroke distance. An air spring is mechanically linked to the cam lever and the pressure pad such that the air spring absorbs a portion of the first stroke distance.

Description:
TECHNICAL FIELD 
     The present application relates generally to carton filling apparatus and more particularly to a carton bottom 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. Mechanically driven systems have been proposed to reduce noise during operation. 
     SUMMARY 
     In an aspect, an apparatus for effecting closure of an open end of a carton blank by placing portions of the carton blank into overlying relationship to one another is provided. The apparatus includes a cam that rotates about an axis of rotation and a cam lever that is operatively connected to the cam. The cam lever is used to convert rotating motion of the cam into linear motion to define a first stroke distance. A pressure pad is mounted for movement toward and away from the portions of the carton blank. The pressure pad is capable of being moved in response to input provided by the cam to define a second stroke distance. An air spring is mechanically linked to the cam lever and the pressure pad such that the air spring absorbs a portion of the first stroke distance. 
     In another aspect, an apparatus for effecting closure of an open end of a carton blank by placing portions of the carton blank into overlying relationship to one another is provided. The apparatus includes a cam that rotates about an axis of rotation and a cam lever that is operatively connected to the cam. The cam lever is used to convert rotating motion of the cam into linear motion. A pressure pad is mounted for movement toward and away from the portions of the carton blank. The pressure pad is capable of being moved in response to input provided by the cam for a carton sealing operation. An air cylinder is mechanically linked to the cam lever, wherein actuation of the air cylinder decouples the pressure pad and the cam such that the pressure pad remains in a retracted position irrespective of movement of the cam. 
     In another aspect, a method for effecting closure of an open end of a carton blank by placing portions of the carton blank into overlying relationship to one another using a bottom sealing apparatus is provided. The method includes mechanically linking a cam and a pressure pad using a cam lever and an air spring. The cam lever converts rotating motion of the cam into linear motion defining a first stroke distance. The pressure pad is capable of being moved in response to input provided by the cam defining a second stroke distance. A portion of the first stroke distance is absorbed using the air spring. 
     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 selected components of an embodiment of a bottom sealer apparatus of use in the carton filling apparatus of  FIG. 1 ; 
         FIG. 3  is a detail view of the bottom sealer apparatus of  FIG. 2 ; 
         FIG. 4  is another detail view of the bottom sealer apparatus of  FIG. 2  with components removed; 
         FIG. 5  schematically illustrates an embodiment of a control system for use in controlling the bottom sealer apparatus of  FIG. 2 ; and 
         FIG. 6  schematically illustrates the control system of  FIG. 5  with energized control valves. 
     
    
    
     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 . 
     Referring to  FIG. 2 , a perspective view of certain components of a bottom sealer apparatus  22  for use at station  16  are shown. Bottom sealer apparatus  22  includes a first bottom sealer mechanism  24  for use in sealing cartons traveling along a first carton sealing line and a second bottom sealer mechanism  26  for sealing cartons traveling along a second carton sealing line. In alternative embodiments, only one or more than two bottom sealer mechanisms  24 ,  26  may be utilized. 
     In the illustrated embodiment, both sealer mechanisms  24  and  26  are driven by a rotating cam  28  (e.g., an open-face cam, a closed-face cam or a combination thereof) and a cam lever  30  including a roller  32  that rides along a cam surface  34  as the cam rotates. With cam  28  rotation about axis A, the cam lever  30  moves vertically in the direction of arrow  36  to define a cam stroke distance. Cam surface  34  can be formed using a computer generated profile for controlling acceleration and deceleration of the sealer mechanisms  24 ,  26 , which can provide smooth motion, e.g., without any abrupt starts or stops. 
     A push rod  38  connects an end  40  of the cam lever  30  to a first arm member  43 , which is rigidly coupled to both a secondary shaft  42  and an air cylinder frame  44  by a connecting rod  46 . Secondary shaft  42  transfers force generated due to rotational motion of the first arm member  43  to a second arm member  48  rigidly connected to the secondary shaft to rotate the second arm member in a similar or identical fashion to the first arm member. In some embodiments, the first and second arm members  43  and  48  rotate in an arc from an initial position through between about 10 and 90 degrees (e.g., from an initial position through about 30 and 45 degrees) due to the movement of the push rod  38 . The second arm member  48  is rigidly coupled to an air cylinder frame  50  that is disposed at a side of the bottom sealer apparatus  22  that is opposite that which the air cylinder frame  44  is located by a connecting rod  52 . 
     An air cylinder  54 ,  56  is fixedly coupled to each cylinder frame  44 ,  50 . Each air cylinder  54 ,  56  includes a respective cylinder rod  58 ,  60  that is connected to a respective actuator lever  62 ,  64 . As can be appreciated, as the first and second arm members  43  and  48  move in their arcs due to their linkages to the cam  28 , the air cylinders  54 ,  56  move in the direction of arrow  74  due to the cylinders&#39; linkages to the frames  44 ,  50 . The actuator levers  62 ,  64  pivot about a respective axis  76  due to the motion of the air cylinders  54 ,  56  and the linkage between the cylinder rod  58 ,  60  and the actuator lever. Referring now to  FIG. 3 , the actuator levers  62 ,  64  are each fixedly coupled to a roller arm (only roller arm  66  and actuator lever  62  are depicted) that carries a roller  68 . The roller arm  66  also pivots about axis  76  due to its linkage with the actuator lever  64 . The roller  68  rides along a surface  78  of a cam block  70  to extend and retract a sealing pad  72  to define a pad stroke distance for a sealing operation. In some embodiments, the sealing pad  72  is biased toward the retracted position (e.g., by a spring). Referring also to  FIG. 4 , as the roller  68  rotates upward, the roller causes the cam block  70  to extend the sealing pad  72  due to the shape of the surface  78 . The cam block  70  can be shaped to maintain a uniform force multiplication ratio as pressure is applied to a carton bottom with the sealing pad  72 . 
     Referring to  FIG. 5 , air cylinders  54  and  56  are controlled through use of control circuit  80 . Control circuit  80  includes an exhaust reservoir  82 , a supply reservoir  84  and a surge tank  86 . Surge tank  86  serves as a reservoir for sending compressed air to and from the air cylinders  54 ,  56 . An air pressure regulator  88  controls the pressure in the surge tank  86  and control circuit  80 . The pressure can be increased in the surge tank  86  to increase the force applied to the carton or lowered to decrease the force applied to the carton. Control circuit  80  further includes control valves  90  and  92  (shown in their de-energized positions). The control valves  90  and  92  are used to extend and retract the cylinder rods  58  and  60 . 
     With the control valves  90  and  92  de-energized as shown by  FIG. 5 , pressurized air is delivered from the pressure regulated surge tank  86  to the air cylinders  54 , which causes the cylinder rods  58  and  60  to extend. By extending the cylinder rods  58  and  60 , the roller  68  disengages the cam block  70  so that the sealing pads  72  remain in their retracted positions, even in instances where the cam  28  continues to rotate (see  FIGS. 3 and 4 ). Disengaging the roller  68  from the cam block  70  (e.g., when there are no cartons being sealed) can eliminate unnecessary sealing pad  72  motion, which can reduce wear and extend the life of bottom sealer components. A controller (not shown) may be used to automatically control actuation of the control valves  90 ,  92 ). 
     Referring now to  FIG. 6 , the control valves  90  and  92  can be actuated (e.g., when cartons are present for a sealing operation) to send compressed air from the pressure regulated surge tank  86  to retract the cylinder rods  58  and  60 . Referring also to  FIGS. 3 and 4 , by retracting the cylinder rods  58 ,  60 , the roller  68  can engage the cam block  70  so that the roller  68  rides along the surface  78  of the cam block  70  to extend and retract the sealing pad  72  (e.g., a stroke distance of about 0.5 inch) in response to rotation of the cam  28  as described above. 
     The air cylinders  54  and  56  are used to transmit cam  28  motion to the sealer mechanisms  24  and  26  to operate the sealer pads  72 . Most of the stroke distance of the sealing pad  72  is used to move the sealer pad into a preliminary sealing position. A final portion of the pad stroke distance is used to compress a carton bottom to create a bottom carton seal. The length of this final portion of pad stroke distance is dependent on, for example, carton board thickness and any freeplay in the linkage connections described above between the cam  28  and the sealing pad  72 . Thus, it is desirable for the cam  28  to provide some greater amount of stroke distance than is actually required to effectuate a seal using the sealing pad  72 . To reduce the probability of damage due to the stroke distance provided by the cam  28 , this greater amount of stroke is absorbed by the air cylinders  54  and  56 , when the air cylinders are in their retracted positions, through forced extension of the air cylinder rods  58  and  60  when the sealing pad reaches its maximum pad stroke distance. As such, the air cylinders  54 ,  56  each operate as an air spring that absorbs a portion of the stoke distance provided by the cam  28 . As used herein, an air spring refers to a spring operated using air or other compressible fluid under pressure. While air cylinders  54 ,  56  are shown and described, other suitable components may be used to form air springs, such as air bladders, air bellows, etc. 
     In some embodiments, as the air cylinders rods  58  and  60  are forced to extend, absorbing the final amount of cam stroke distance, the air cylinders maintain substantially a constant spring force. This constant spring force is due air being allowed to flow from the air cylinders  54  and  56  back to the surge tank  86 , which has a much larger volume (e.g., ten times the volume or more) than the volume change in the air cylinders. During a normal sealing operation, air can be allowed to flow back to and from the surge tank  86  so that little or no compressed air is consumed. 
     By providing control system  80 , 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.