Patent Publication Number: US-6339914-B1

Title: Packaging machine

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to packaging machines for containers, such as cartons for containing milk, and, more particularly, to packaging machines including a bottom breaker. 
     Packaging machines of the type mentioned are already known for use with tubular containers of square to rectangular cross section. The containers each have a bottom forming portion comprising first to fourth bottom panels continuous with one another, the first bottom panel having a pair of cuts formed in the center of the outer end thereof to provide a fold forming portion between these cuts for preventing a liquid from permeating the end. The packaging machine comprises a rotor having radial mandrels and intermittently drivable so as to stop each of the mandrels at first and second process stations in succession, the container being fitted around the mandrel with the bottom forming portion projecting therefrom and with the first bottom panel facing to the right, a bottom breaker for prefolding the bottom forming portion of the container as fitted around the mandrel stopped at the first station so as to render the bottom forming portion foldable flat and for prefolding the fold forming portion by bending the fold forming portion rightward along a base part thereof, a folding rail for guiding the prefolded bottom forming portion of the container fitted around the mandrel from the first station to the second station during the movement of the mandrel from the first to the second station while folding the bottom forming portion flat by contact therewith, and a bottom press for folding flat and bonding under pressure the bottom forming portion of the container fitted around the mandrel as stopped at the second station. The folding rail comprises right and left two rail members, with a clearance formed therebetween for permitting the outer end of the prefolded bottom forming portion of the container fitted around the mandrel to be inserted thereinto during the movement from the first to the second station. 
     The packaging machine described above has the problem that while the bottom forming portion moves along the folding rail, the prefolded fold forming portion restores itself to the original state owing to the property of the container material to spring back, with the result that the bottom forming portion including the fold forming portion can not be folded satisfactorily to the specified shape. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a packaging machine which is adapted to prevent the prefolded fold forming portion from restoring itself owing to the springing-back property of the container material. 
     The present invention provides a packaging machine for tubular containers of square to rectangular cross section, each of the containers having a bottom forming portion comprising first to fourth bottom panels continuous with one another, the first bottom panel being formed with a fold forming portion in a center of an outer end thereof for preventing a liquid from permeating the end, the packaging machine comprising: a movable body having mandrels and intermittently drivable so as to stop each of the mandrels at first and second process stations in succession, the container being fitted around the mandrel with the bottom forming portion projecting therefrom and with the first bottom panel facing to the right, a bottom breaker for prefolding the bottom forming portion of the container as fitted around the mandrel stopped at the first station so as to render the bottom forming portion foldable flat and for prefolding the fold forming portion by bending the fold forming portion rightward along a base part thereof, a folding rail for guiding the prefolded bottom forming portion of the container fitted around the mandrel from the first station to the second station during the movement of the mandrel from the first to the second station while folding the bottom forming portion flat by contact therewith, and a bottom press for folding flat and bonding under pressure the bottom forming portion of the container fitted around the mandrel as stopped at the second station, the folding rail comprising right and left two rail members with a clearance formed therebetween for permitting an outer end of the prefolded bottom forming portion of the container fitted around the mandrel to be inserted thereinto during the movement from the first to the second station. The packaging machine is characterized in that an unfolding preventing guide member is disposed in the rail clearance so as to come into contact with a required part of the bottom forming portion during movement through the clearance. 
     With the packaging machine of the present invention, the clearance between the two rail members has disposed therein an unfolding preventing guide member which comes into contact with the required part of the bottom forming portion during movement through the clearance, so that the guide member prevents the prefolded fold forming portion from restoring itself to the original state owing to the property of the container material to spring back. 
     The part of the bottom forming portion to be brought into contact with the guide member during the movement through the rail clearance is the left side of the base part of the fold forming portion. Even if the prefolded fold forming portion acts to fall down leftward for unfolding, this portion is then prevented from falling down by contact with the guide member, and is unlikely to unfold. 
     The folding rail starts to fold the prefolded bottom forming portion of the container fitted around the mandrel during the movement from the first to the second station upon the bottom forming portion coming into contact with the rail members, and the left side of the base part of the fold forming portion is brought into contact with the guide member after the bottom forming portion has moved a predetermined distance from the time of coming into contact with the rail members. Since the folding rail folds the bottom forming portion immediately after the guide member prevents the fold forming portion from falling down in this case, the guide member acts on the fold forming portion at the most suitable position. 
     When the guide member comprises a roller having a rotary shaft extending orthogonal to the direction of movement of the mandrel, the guide member is unlikely deface or damage the container. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side elevation of a packaging machine of the invention; 
     FIG. 2 is a side elevation of a bottom breaker of the packaging machine; 
     FIG. 3 is a view of the same as it is seen in the direction of arrows of the line III—III in FIG. 2; 
     FIG. 4 is a perspective view of a third prefolding member included in the bottom breaker; 
     FIGS.  5 ( a ),  5 ( b ) and  5 ( c ) are diagrams for illustrating the folding operation of the bottom breaker; 
     FIG. 6 is a perspective view of a folding rail and a guide member of the packaging machine; 
     FIGS.  7 ( a ),  7 ( b ) and  7 ( c ) are diagrams for illustrating the folding operation of the folding rail; 
     FIG. 8 is a perspective view of a container for use in the packaging machine; 
     FIG. 9 is a plan view of the bottom portion of the container as it is seen from inside after folding; and 
     FIG. 10 is a plan view corresponding to FIG.  9  and showing a container bottom portion having a different structure. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     An embodiment of the present invention will be described next with reference to the drawings. 
     In the following description, the terms “front” and “rear” refer respectively to the left-hand side and the right-hand side of FIG. 1, and the terms “left” and “right” are used for the machine as it is seen from the rear forward. 
     FIG. 8 shows a container  11  as turned upside down. The container  11  comprises a trunk forming portion  12  to be made into a trunk, a top forming portion  13  to be made into a top portion, and a bottom forming portion  14  to be made into a bottom portion. 
     The bottom forming portion  14  comprises first to fourth rectangular bottom panels  21  to  24  joined to one another endlessly. The second and fourth bottom panels  22 ,  24  are each formed with an inverted V-shaped score  25 . The first bottom panel  21  is formed in the center of its outer end with a pair of cuts  26  extending in parallel to the axis of the container. The portion between the cuts  26  provides a fold forming portion  27  for preventing penetration of liquid into the end face. 
     The bottom forming portion  14  is folded in the following manner. First, the second and fourth bottom panels  22 ,  24  are folded inward while being folded each in two along the score  25 , and the first and third bottom panels  21 ,  23  are then folded over the second and fourth bottom panels  22 ,  24  thus folded. The outer end portion of the first bottom panel  21  including the fold forming portion  27  is inserted between the third bottom panel  23  and triangular portions of the second bottom panel  22  and the fourth bottom panel  24 . In this case, the fold forming portion  27  is folded over the portion of the panel  21  adjoining the base part of the portion  27  before the insertion. 
     FIG. 9 shows the bottom forming portion  14  eventually folded flat as it is seen from inside the container. If the first bottom panel  21  had no fold forming portion  27  as seen in FIG. 10, the portion B of the panel  21  corresponding to the portion  27  would be exposed inside the container between the folded-over triangular portions of the second and fourth bottom panels  22 ,  24 . After the container is filled with a liquid, the liquid would then permeate the end face of the portion B corresponding to the fold forming portion  27  of the first bottom panel  21 . However, the fold forming portion  27 , which is folded over as described above, is covered with the first bottom panel  21  and the folded-over triangular portions of the second and fourth bottom panels  22 ,  24 , whereby the liquid is prevented from permeating the portion  27 . 
     FIG. 1 shows a packaging machine which comprises an intermittently drivable rotor  32  having eight radial mandrels  31  so arranged as to revolve counterclockwise as indicated by an arrow A in FIG.  1  and successively stop at eight stations, i.e., first to eighth process stations I to VIII, a feeder  33  disposed at the first process station I, a bottom heater  34  disposed at the fourth process station IV, a bottom breaker  35  disposed at the fifth process station V, a folding rail  36  extending from the fifth process station V to the sixth process station VI, a bottom press  37  disposed at the sixth process station VI, an unloader  38  disposed at the eighth station VIII and a container conveyor  39  having the starting end of a path of transport at the eighth station VIII. 
     The second, third and seventh process stations II, III and VII are all idle stations. A preheater and other devices are provided at the idle stations. 
     The direction of revolution of the mandrel is indicated by an arrow A in FIG.  8 . The container  11  is fitted around the mandrel  31  with its bottom forming portion  14  projecting radially outwardly therefrom and with the first bottom panel  21  facing radially inwardly. 
     As shown in detail in FIGS. 2 and 3, the bottom breaker  35  comprises a pair of first prefolding members  41  to be opened and closed in the direction of movement of the mandrel at the fifth station V, a pair of second prefolding members  42  to be opened and closed orthogonally of the direction of movement of the mandrel at the fifth station V, and a third prefolding member  43  pivotally movable about an axis extending in a direction across, and at the right of, the axis of the mandrel  31  stopped at the fifth station V. 
     A yoke  44  secured to a machine frame by suitable means is provided externally of the mandrel  31  as halted at the fifth station V. Supported by the yoke  44  are a pair of first pivots  45  arranged side by side in the direction of movement of the mandrel and extending transversely of this direction, and a pair of second pivots  46  extending transversely of these pivots  45 . The yoke  44  is further provided with a bracket  47  extending obliquely downward in the rear of the second prefolding member  42  at the right. Mounted on the lower end of the bracket  47  is a support rod  48  extending in parallel to the second pivots  46 . 
     The first prefolding members  41  are in the form of arms extending inward from the respective first pivots  45  and each have a triangular pressure plate  51  at the inward end. The second prefolding members  42  are in the form of arms extending inward from the respective second pivots  46  and each have a round pressure bar  52  at the inward end. The first pivots  45 , as well as the second pivots  46 , are rotated in directions opposite to each other reversibly by unillustrated drive means. As a result, the first prefolding members  41  are opened and closed to move their pressure plates  51  away from and toward each other, and the pressure bars  52  of the second prefolding members  42  are also similarly moved. When closed, the first prefolding members  41  have their pressure plates  51  brought into pressing contact with the second and fourth bottom panels  22 ,  24 , respectively, and the second prefolding members  42  have their pressure bars  52  into pressing contact with the first and third bottom panels  21 ,  23 . 
     The third prefolding member  43  is in the form of an L-shaped arm attached to the support rod  48  as if extending across the first bottom panel  21  of the bottom forming portion  14  of the container  11  as fitted around the mandrel  31  halted at the fifth station V. The member  43  comprises a base-end arm portion  61  in the form of a strip and extending leftward from the support rod  48 , and an outer-end arm portion  62  in the form of a strip and obliquely extending forwardly downward from the outer end of the arm portion  61 . 
     The outer-end arm portion  62  is provided with a wide portion  63  extending downward from the outer end thereof, and a pair of arms  64  extending leftward in parallel to each other from the wide portion  63  and orthogonal thereto. The distance between the two arms  64  is slightly smaller than the width of the fold forming portion  27 . The lower end of the wide portion  63  projects downward beyond the base parts of the arms  64 . The arms  64  have lower faces providing a folding guide face  65 , and outer ends providing a fortified folding face  66 . The folding guide face  65  and the fortified folding face  66  make an angle of about 90 deg. 
     The third prefolding member  43  has an arm extension  67  projecting rightward from its base portion. The right end of the extension  67  is connected to the piston rod  69  of a fluid pressure cylinder  68  mounted on the yoke  44  and directed downward. The cylinder  68  is of the two-step stroke type. 
     With reference to FIG.  5 ( a ), the third prefolding member  43  is in a nonoperative position P 0  when the cylinder  68  is in an advanced position. The member  43  is in a first operative position P 1 , as shown in FIG.  5 ( b ), when the cylinder  68  is in a first stroke position, and the member  43  is in a second operative position P 2 , as shown in FIG.  5 ( c ), when the cylinder  68  is in a second stroke position. 
     When the container  11  is to be fed to the fifth station V, the first and second prefolding members  41 ,  42  are each in the open position, with the third prefolding member  43  in its nonoperative position P 0 . The third prefolding member  43  in the nonoperative position P 0  is positioned externally of the bottom forming portion  14  of the container  11 . 
     When the container  11  is delivered to the fifth station V, the piston rod  69  of the cylinder  68  is moved to the first stoke position, bringing the third prefolding member  43  to the first operative position P 1 . Subsequently, the first and second prefolding members  41 ,  42  start to move from the open position toward the closed position at the same time. In the course of this movement, the first prefolding members  41  first inwardly fold the second and fourth bottom panels  22 ,  24  along the respective scores  25 , and the second prefolding members  42  then inwardly fold the first and second bottom panels  21 ,  23  over the folded second and fourth bottom panels  22 ,  24 . 
     FIGS.  5 ( a ) and  5 ( b ) show the curve M representing the path of movement of the outer end of the first bottom forming panel  21  during folding. The third prefolding member  43  moves across this curve M. The folding guide face  65  moves away from the path M inwardly thereof as the guide face  65  advances. Accordingly, when the first bottom panel  21  is moved toward a closed position with the third prefolding member  43  in the first operative position P 1 , the fold forming portion  27  collides with the projecting lower end wide portion  63  of the third prefolding member  43  and is bent rightward along the base part thereof. The fold forming portion  27  moves along the folding guide face  65  after moving past the projecting lower end of the portion  63 , whereby the bending angle of the fold forming portion  27  is gradually increased. 
     When the second prefolding members  42  are eventually brought to the closed position shown in FIG. 5, ( c ), the first and third bottom panels  21 ,  23  are bent at an angle of about 45 deg with respect to the center line of the container, and the fold forming portion  27  is bent at an angle of about 90 deg with respect to the first bottom panel  21 . 
     When the second prefolding members  42  are brought to the closed position, the cylinder piston rod  69  is moved to the second stroke position, whereby the third prefolding member  43  is further pivotally moved to the second operative position P 2  shown in FIG.  5 ( c ). In this position, the fortified folding face  66  of the third prefolding member  43  is approximately in contact with the first bottom panel  21 . This means that the distance from the center of pivotal movement of the third prefolding member  43  to the first bottom panel  21  in the eventual folded position is approximately equal to the radius of pivotal movement of the fortified folding face  66 . 
     When the third prefolding member  43  is brought to the second operative position P 2 , the fortified folding face  66  of the member  43  presses the fold forming portion  27  against the part of the first bottom panel  21  adjacent to the base of the portion  27  to lap the portion  27  over the adjacent part. The fold forming portion  27  in its initial raised position is folded through 180 deg in this way. When the portion  27  is thus prefolded or given a folding tendency, it is unlikely that the fold will be removed from the portion  27  by the springing back of the container material. 
     The fluid pressure cylinder piston rod  69  is thereafter advanced by the distance of two-step stroke, pivotally moving the third prefolding member  43  upward, and the first and second prefolding members  41 ,  42  are moved away from the container  11 . 
     Since the third prefolding members  43  is operated by a drive source different from that for the first and second prefolding members  42 ,  42 , the operation timing of these members can be determined as desired, while the third prefolding member  43  only can be brought out of operation. 
     As shown in detail in FIG. 6, the folding rail  36  comprises left and right rail members  71 ,  72 . The rail members  71 ,  72  are each generally in the form of a circular-arc plate centered about the center of rotation of the rotor  32 . Stated more precisely, the rail members  71 ,  72  are positioned closer to the center of rotation of the rotor  32  as they extend from the fifth station V toward the sixth station VI. 
     Formed between the two rail members  71 ,  72  is a clearance C for inserting the folded bottom forming portion  14  thereinto. The clearance C comprises a first section C 1 , second section C 2  and third section C 3  continuously arranged in the direction of movement of the mandrel. 
     FIGS.  7 ( a ),  7 ( b ) and  7 ( c ) show how the bottom forming portion  14  is folded as it is moved through the first to third sections C 1 , C 2  and C 3  in succession. 
     In the first section C 1 , the rail members  71 ,  72  start to fold the bottom forming portion  14  upon the portion  14  coming into contact with these members. In the second section C 2 , the portion  14  is folded to an extent that the outer end of the first bottom panel  21  is positioned beneath free end of the third bottom panel  23 . The bottom forming portion  14  is folded almost flat in the third section C 3 . 
     A guide roller  73  is disposed at the approximate midportion of the first section C 1 . A rotary shaft for the guide roller  73  extends transversely of an extension of axis of the mandrel  31  moving past the guide roller  73 . The guide roller  73  has an outer periphery positioned in the clearance C at a position slightly to the right of the path of movement of the center of the mandrel  31 . 
     FIG.  7 ( a ) shows the bottom forming portion  14  as it moves past the guide roller  73 . At this time, the outer periphery of the guide roller  73  is in pressing contact with the left side part of the base of the fold forming portion  27 . Further, before and after the fold forming portion  27  moves past the guide roller  73 , the outer periphery of the guide roller  73  presses the first bottom panel  21  on extension lines of the base part of the fold forming portion  27 . The fold forming portion  27  is distinctly bent from the other portion of the first bottom panel  21  by the guide roller  73  and can therefore be reliably folded as shown in FIGS.  7 ( b ) and  7 ( c ). 
     It is desirable that the guide roller  73 , which is to be provided in the first section C 1 , be disposed immediately before the second section C 2 . 
     The embodiment described above can be modified variously as will be described below. 
     A pair of cuts are formed in the midportion of outer end portion of the first bottom panel to provide the fold forming portion between the cuts for preventing the liquid from permeating the panel end face, whereas a container is known which has a fold forming portion projecting upward from the midportion of outer end of a first bottom panel (see JP-Y No. 59-22015). The fold forming portion of such a container can be prefolded also by the third prefolding member of the invention. 
     Although the mandrels are arranged radially about a horizontal axis of rotation, a packaging machine is also known wherein mandrels are suspended from the peripheral portion of a horizontal rotary plate which has a vertical axis of rotation (see JP-A No. 61-127403). The invention is applicable also to this packaging machine. 
     Furthermore, mandrels may be disposed outwardly upright at an endless chain rotating inner vertical face. 
     Although the rotor shown has eight mandrels, a rotor having six mandrels is also known well. 
     The first prefolding members, as well as the second prefolding members, are paired and closable for prefolding, whereas a bottom breaker is know which has a first prefolding member and a second prefolding member which are movable straight toward and away from the end face of the mandrel axially of the mandrel, at least one of the first and second prefolding members being adapted to prefold the container by the straight movement only with closing (see JP-U No. 3-8107). The third prefolding member can be used in combination with the first and second prefolding members thus adapted. 
     The guide roller may be replaced, for example, by a barlike fixed guide member extending toward the direction of movement of the container. It is then, desirable that the surface of the fixed member to be brought into contact with the container be coated with Teflon. This prevents the frictional contact of the guide member with the container from producing polyethylene fragments or particles on the container surface.