Patent Publication Number: US-8534032-B2

Title: Method for placing inert gas in gas-filling packaging machine

Description:
TECHNICAL FIELD 
     The present invention relates to a method for filling a gas-filling packaging machine with an inert gas, in which machine gas replacement is carried out by supplying the inert gas from a nozzle into a packaging bag previously filled with articles so that air in the bag is expelled out and a top of a packaging bag is subsequently sealed. 
     BACKGROUND ART 
     A method for filling a conventional gas-filling packaging machine with an inert gas is disclosed in JP-A-2004-67224 by the present applicant. The gas-filling packaging machine is constructed so that a single intermittently rotating table is used for filling a packaging bag with articles, filling an inert gas such as nitrogen gas and heat-sealing a top of the bag after the bag has been filled with the articles and inert gas. A nozzle for filling with the inert gas is constructed so as to be fixed to an outer surface of a filling funnel provided on a packaging bag the top of which is open. The filling funnel has a discharge hole which rises and sets relative to the packaging bag. 
     The nozzle for filling the packaging bag with the inert gas employs such a structure as to be fixed to the outer surface of the filling funnel as described in the foregoing gazette or such a structure as to be fixed to a central inside of the filling tunnel. However, a distal end of the nozzle is inserted into a corner of the packaging bag in the former fixing structure. Accordingly, when the packaging bag is a flat bag or a packaging gusset bag e as shown in  FIG. 8 , the distal end of the nozzle tends to be easily detached from the top of the bag. Furthermore,  FIG. 9  shows a chuck bag a with side gusset. The chuck bag a has both sides with folds c respectively. There is a rare defect that the distal end of the nozzle n sticks into inwardly extending parts of the folds c. 
     In the latter nozzle fixing structure, the nozzle fixed to the central inside of the filling funnel constitutes a barrier to the article passing, resulting in an increase in the filling time. As a result, the filling funnel is clogged by the article in some cases. 
     Furthermore, in the inert gas filling method described in the above gazette, gas replacement is not carried out while the top of the bag is closed. Accordingly, gas replacement is sometimes unfavorable depending upon a type or size of a packaging bag or a type of the article.
     Patent Document: JP-A-2004-67224   

     DISCLOSURE OF THE INVENTION 
     An object of the present invention is to provide an inert gas filling method in a gas-filling packaging machine, which method can overcome defects in the case where the gas-filling nozzle a is inserted into a packaging bag and a gas replacement rate can be improved. 
     Means for Overcoming the Problem 
     To achieve the object, the present invention described in claim  1  is a method for placing an inert gas in a gas-filling packaging machine in which a rotating body is provided with a number of pairs of radial grips and filling funnels disposed so as to correspond to the paired grips and so as to be vertically movable and is intermittently stopped and moved for every one of a plurality of steps by an intermittent drive unit in a filling sep so that a packaging bag suspended by each grip pair is filled with a predetermined amount of article to fill the packaging bag and an inert gas is blown out of a gas-filling nozzle provided on each filling funnel so that air is replaced by the inert gas in the packaging bag and subsequently, a top of the bag is sealed, wherein the gas-filling nozzle has a distal end which is movable so as to get close to and to depart from an imaginary perpendicular line passing a center of a drop mouth of each filling funnel by a nozzle attitude control unit; prior to a filling step, the drop mouth of the filling funnel and the distal end of the gas-filling nozzle close to the perpendicular line are inserted from the open top of the packaging bag into the bag and simultaneously, the distal end of gas-filling nozzle is departed from the perpendicular line thereby to be moved toward a corner of the packaging bag; replacement is carried out between the inert gas blown out of the gas-filling nozzle and air in the packaging bag at the filling step and/or a step subsequent to the filling step; and at another step subsequent to the filling step, the replacement between the inert gas and the air in the bag is accelerated while the top of the bag is substantially closed by a shutter unit and thereafter, the bag top is released from a closed state and thereafter, the gas-filling nozzle is pulled out of the packaging bag. 
     To achieve the same object, the invention described in claim  2  is characterized in that in the invention described in claim  1 , the nozzle attitude control unit includes a holder which is provided on a side of the filling funnel so as to be rockable and to which an upper end of the gas-filling nozzle is fixed and a roller which is provided on the holder so as to be rotatable; when the filling funnel is intermittently stopped at the step prior to the filling step, the roller is caused to abut against a cam plate disposed so as to be vertically elongated at the step, whereby the distal end of the gas-filling nozzle is close to the perpendicular line; and the filling funnel is moved downward so that the distal end of the gas-filling nozzle is inserted into the packaging bag and so that the distal end is departed from the perpendicular line thereby to be moved to the corner side of the packaging bag. 
     To achieve the same object, the invention described in claim  3  is characterized in that in the invention described in claim  1  or  2 , the packaging bag is a flat bag, a packaging bag having folds on both sides respectively except for the top thereof or a gusset bag. 
     Effect of the Invention 
     According to the invention described in claim  1 , the distal end of the gas-filling nozzle is inserted into the packaging bag while being close near to the center of the drop mouth of the filling funnel by the nozzle attitude control unit. Accordingly, an erroneous insertion and defect of the nozzle can be resolved. More specifically, the nozzle can be prevented from disengaging from the open top of the bag when inserted into the bag. Furthermore, the nozzle can be prevented from sticking into the folds of the packaging bag of the gusset type. Additionally, since the final gas replacement is carried out while the bag top is closed by the shutter unit, the gas replacement rate is improved. 
     According to the invention described in claim  2 , the structure of the nozzle attitude control can be simplified and a gas filling work can carried out smoothly and stably. 
     According to the invention described in claim  3 , the method can be applied to various types of packaging bags such as a flat bag, a packaging bag having folds on both sides respectively except for the top thereof (side gusset chuck bag) or a gusset bag, whereupon a gas filling work can carried out smoothly and stably. 
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     A best mode of the present invention will be described with reference to the accompanying drawings.  FIG. 1  is a side view of the gas-filling packaging machine to which the method for filling a gas-filling packaging machine with an inert gas is applied.  FIG. 2  is a plan view of the machine.  FIG. 3  is a side view of a rotating body, a filling funnel and peripheral structure.  FIG. 4  is a view explaining a nozzle attitude control unit.  FIG. 5  is a development of cam rail showing the relative positional relationship among a filling funnel, gas-filling nozzle and packaging bag over a whole process.  FIG. 6  is a side view of a shutter unit showing execution of gas replacement with the bag top being closed.  FIG. 7  is a plan view of the shutter unit shown in  FIG. 6 . 
       FIGS. 1 and 2  show a gas-filling packaging machine P to which the method of the invention for filling a gas-filling packaging machine with an inert gas is applied. The rotary gas-filling packaging machine P comprises a weighing device (not shown) supplying a predetermined amount of article to a filling funnel and an inert gas supplier as shown in  FIG. 2 . The machine carries out ten steps including a bag feeding step A, step B of opening a chuck of packaging bag, step C of swelling a lower part of the bag when the bag is a gusset bag, step D of opening the top of the bag, step E of filling an article to be packed, vibrating steps F and G, idling step H, step I of closing the chuck and heat-sealing the bag top and step J of cooling a sealed part and releasing products. 
     The embodiment will be described with a side gusset chuck bag (hereinafter referred to as “packaging bag”) having folds on both sides respectively except for the top thereof as shown in  FIG. 9 . 
     The method of the invention may be applied to a flat bag, a packaging bag having folds on both sides respectively except for the top thereof or a gusset bag. 
     A stand  3  is mounted on a mounting  1  of the packaging machine P for rotatably supporting a vertically elongated intermittent rotational shaft  2  rotated by a drive unit (not shown). A disc-shaped rotating body  4  is mounted on the intermittent rotational shaft  2 . On the rotating body  4  are mounted ten pairs of grips  9  (the same number as the steps) for gripping and releasing a packaging bag a which is provided with a chuck d and which is open only at a top thereof. The grips  9  are provided so as to protrude radially at equiangular intervals. The intermittent rotational shaft  2  has an upper end on which a boss  7  of a drum  6  is supported by a plurality of bearings  5  so that the drum  6  is rotatable. The drum  6  is fixed just over the rotating body  4  so as to be concentric with the intermittent rotational shaft  2 . 
     A pair of guide bars  15  stands in parallel on the outer peripheral edge  4   a  of the aforesaid rotating body  4  so as to correspond to a central position of each paired grips  9 , as shown in  FIG. 3 . The guide bars  15  have respective upper ends which are mounted on a ring plate  16 . Reference symbol  17  designates a slide plate  17  attached to the paired guide bars  15  so as to be vertically movable. A bracket  19  is provided in front of the slide plate  17  for mounting a filling funnel  21 . A cam roller  20  rotatably protrudes on the central rear of the slide plate  17 . 
     The same number of filling funnels  21  as the number of steps is provided. The filling funnels  21  are provided with gas filling nozzles  23  respectively. As shown in  FIG. 41  each gas filling nozzles  23  is provided so that a distal end  23   b  thereof comes close to and departs from an imaginary perpendicular line v passing through the center of a drop opening  21   a  of the filling funnel  21 . 
     The foregoing nozzle attitude control unit  25  will now be described in detail. The nozzle attitude control unit  25  includes a holder  28  is supported by a shaft  27  on the block  26  mounted on a horizontal portion  19   a  of the bracket  19  so that the holder  28  is rockable in a direction horizontal to the aforesaid perpendicular line v. The holder  28  has an L-shape as viewed from the side and includes a horizontal piece  28   a  to which the upper end  23   a  of the gas filling nozzle  23  is fixed and a vertical piece  28   b  on which a roller  30  is rotatably mounted. The gas filling nozzle  23  has a distal end  23   b  which protrudes a predetermined dimension below the drop opening  21   a  of the filling funnel  21  and is provided so as to normally retain the perpendicular attitude. Reference symbol  31  designates a rubber piece interposed between the block  26  and the horizontal piece  28   a  of the holder  28  and having a spring function. 
     When the filling funnel  21  is intermittently stopped at an opening step D prior to a filling step E, the roller  30  is abutted against the cam plate  29  disposed so as to be vertically elongated at the step, so that the distal end  23   b  of the filling nozzle  23  is moved to be come close to the aforesaid perpendicular line v. As the result of downward movement of the filling funnel  21 , the distal end  23   b  of the gas filling nozzle  23  is inserted into the packaging bag a. Thereafter, the roller  30  is detached from the cam plate  32 , whereby the distal end  23   b  is departed from the perpendicular line v thereby to be moved to a corner side of the packaging bag a. 
     When the distal end  23   b  of the gas filling nozzle  23  is moved to be close to the perpendicular line, the middle portion of the nozzle  23  enters a notch  21   b  formed in the filling funnel  21 . 
     The drum  7  has an outer surface in which cam surfaces of lower cam rails  35   a  to  35   c  and cam surfaces of upper cam rails  36   a  to  36   c  are opposed to each other so that cam grooves  37  having predetermined intervals, as shown in  FIG. 5 . The cam roller  20  of the slide plate  17  is inserted into the cam groove  37 , and the cam roller  20  is born by the cam rails  35   a  to  35   c . The movement of the rotating body  4  by the intermittent rotation causes the cam roller  20  of each slide plate  17  to roll on the lower cam rails  35   a  to  35   c , whereby the filling funnel  21  mounted on each slide plate  17  and the gas filling nozzle  23  are vertically moved together. 
     A slider mechanism is provided in the drum  7  in the packaging bag opening step D. A slider  40  having a square guide bar  39  standing thereon is loosely fitted in the slider mechanism so as to be movable. The slider  40  is movable upward and downward by an elevation unit comprising a mechanism (not shown) comprising a cam and a lever or the like. A supporting piece  41  is provided on a front surface of the slider  40  to receive the cam roller  20  of the slide plate  17 . Furthermore, a similar slider mechanism is provided in the idling step H, and the similar components in the idling step H are labeled by the same reference numerals as in the opening step D. The description of these components will be eliminated. 
     The mechanism for moving the number of filling funnels upward and downward by the cam rail on the circumference of the fixed drum is constructed on the basis of the disclosure of Japanese Patent No. 2884064 owned by the applicant of this application. The slider mechanism for moving the filling funnels upward and downward in a specific step is also constructed on the basis of the disclosure of Japanese Patent No. 2884064. 
     Reference numeral  45  designates a rotary valve disposed on the drum  6 . The rotary valve  45  comprises a central valve shaft  45   a  fixed at the drum  6  side and a ring-shaped valve disc  46  rotatably mounted on the valve shaft  45   a . The valve disc  46  is provided with ten gas supply holes (not shown) the number of which is the same as the number of steps. The gas supply holes communicate with a gas passageway of the valve shaft. Furthermore, the valve disc  46  is connected to the ring plate  16  by a stay  47  and is rotatable together with the rotating body  4 . 
     The gas supply holes and the gas filling nozzle  23  are connected to each other by a flexible tube  51 . Furthermore, an inert gas such as nitrogen gas or carbon-dioxide gas adjusted at a predetermined pressure (0.1 to 0.3 MPa) is supplied from an inert gas supply unit  55  through a hose  56  to the valve shaft  45   a  of the rotary valve  45 . The valve shaft  45   a  has an upper end supported by a bearing member  48 . The bearing member  48  is fixed to a connecting plate  50  which connects a pair of posts  49  standing on the mounting  1  to each other. 
     The inert gas supply system is composed on the basis of the disclosure of Japanese Patent No. 2619795 owned by the applicant of this application. 
     A belt-conveyor packaging bag supplying apparatus  60  is disposed at a bag supplying step A. The packaging bag supplying apparatus  60  has a known structure, that is, a number of packaging bags a stacked on a belt-conveyor  61  one upon another with the tops b down. The packaging bags a are separated one by one by a feeder unit  62  to be hung with the tops b up and supplied to the grips  9 . 
     Japanese Utility Model Publication No. JP-Y-H03-5532 discloses an example of the foregoing type of packaging bag supplying apparatus which is related to the present application. 
     A shutter unit  65  is disposed at the idling step H for expediting replacement of air in the packaging bag a by an inert gas while the tops b of the bags a are substantially closed. The shutter unit  65  comprises one shutter member  66  disposed at the front side of the packaging bag and the other shutter member  67  disposed at the rear side of the packaging bag as shown in  FIG. 6 . The shutter members  66  and  67  are opened and closed by actuation of a lever mechanism (not shown). The shutter members  66  and  67  are formed with respective escape grooves  66   a  and  67   a  preventing the gas filling nozzle inserted into the bag a from being broken. 
     The structure of an opening apparatus, a sealing apparatus and the like in the gas filling packaging machine P is based on a known structure and accordingly, a detailed description of the structure will be eliminated. Only part of the structure related with the present invention will be described. 
     Next, the inert gas filling method in the gas filling packaging machine will be described in relation with an operation of the gas filling packaging machine P. 
     (1) The packaging bags a are supplied to the paired grips  9  by the packaging bag supplying apparatus  60  with the bag tops b down at a bag supplying step A. 
     (2) The chucks d of the bags a are opened and a use-by date and the like are printed on the bags by a printing apparatus  65  at a chuck opening step B. 
     (3) The front and rear of the bags a are adsorbed by a pair of adhesive discs  71  of a blowing apparatus  70  so that a lower part of each bag a is blown up, at a blowing step C. This is carried out in order that articles to be packed may be well settled in the bags. 
     (4) The front and rear of each packaging bag a are adsorbed by paired adhesive discs  76  so that the top of each bag a is opened by a known opening apparatus  75 , and a pair of opening and closing pieces b are inserted into each bag b to retain each bag in an open state, at bag opening step D. 
     (5) On the other hand, the cam roller  20  is transferred from the lower cam rail  35   b  to the support piece  41  of the slider  40  which is on standby at an upper position. In this case, since the roller  30  of the nozzle attitude control unit abuts against the ca plate  32 , the distal end  23   b  of the gas filling nozzle  23  is moved close to the perpendicular line, as shown in  FIG. 4 . The slider  40  is then lowered so that the distal end  23   b  of the gas filling nozzle  23  is inserted into the bag a and thereafter, the roller  30  is disengaged from the cam plate  32 . Accordingly, the distal end  23   b  is departed from the perpendicular line thereby to be moved away to a corner of the bag a. As a result, the drop mouth  21   a  of the filling funnel  21  and the distal end  23   b  of the gas filling nozzle  23  are inserted into the bag a. 
     The opening and closing piece  56  of the opening apparatus  55  is moved upward after insertion of the filling funnel  21 , thereby being returned to the V-shaped closed state. 
     (6) The cam roller  20  of the slide plate  17  transferred from the support piece  41  of the slider  40  assuming a lower position to the cam rail  35   c  by the intermittent rotation of the rotating body  4 , and the bag a is intermittently transferred to the article filling step E. 
     (7) A predetermined amount of article to be packed is discharged into the filling funnel by the weighing device at the filling step E, thereby filling the bag a. 
     (8) A distance between the paired grips  9  is increased and the bag top b is stretched straightforward so that external air is prevented from entering the bag a. Simultaneously, the inert gas is spouted from the gas filling nozzle  23 . The replacement of air in the bag a by the inert gas continuously supplied and diffused is enhanced while the bag a is being vibrated by a vibratory device (not shown). 
     (9) The cam roller  20  of the slide plate  17  is transferred from the lower cam rail  35   c  to the support piece  41  of the slider  40  which is on standby at the lower position at an idling step H. After the replacement of air in the bag a by the inert gas is enhanced while the bag top b is substantially closed by the shutter unit  65  as shown in  FIG. 6 , the bag a is released from the closed state. Subsequently, the gas filling nozzle  23  is caused to get out of the bag a by the rise of the slider  40 . 
     (10) The chuck d of the bag a is closed and the bag top is heat-sealed by a sealer  80  at a chuck closing and top heat-sealing step I. 
     (11) Subsequently, a portion heat-sealed at the previous step is cooled by a seal cooler  85  and thereafter, the bag a is caused to fall onto a chute  90  by a releasing operation of the paired grips  9  to be discharged out of the machine. 
     The inert gas is supplied between the vibrating step and the idling step H for the gas replacement in the embodiment. However, the inert gas may be supplied between filling step E and the idling step H for gas replacement. 
     As described above, in the inert gas placing method in the gas filling packaging machine of the present invention, an erroneous insertion and defect of the nozzle can be resolved. More specifically, the nozzle can be prevented from disengaging from the open top of the bag when inserted into the bag. Furthermore, the nozzle can be prevented from sticking into the folds of the packaging bag of the gusset type. Additionally, since the final gas replacement is carried out while the bag top is closed by the shutter unit, the gas filling work can be carried out smoothly and stably. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a side elevation of a gas filling packaging machine to which the inert gas filling method of the present invention is applied; 
       FIG. 2  is a plan view of the gas filling packaging machine to which the inert gas filling method of the present invention is applied; 
       FIG. 3  is a side elevation of a rotating body, filling funnel and the peripheral structure; 
       FIG. 4  is a view explaining a nozzle attitude control unit; 
       FIG. 5  is a development of a cam rail showing the relative positional relationship among the filling funnel, gas filling nozzle and packaging bag in overall steps; 
       FIG. 6  is a side elevation of a part of shutter unit, showing the condition where the gas replacement is to be carried out with the bag top being closed; 
       FIG. 7  is a plan view of the shutter unit; 
       FIG. 8  is a view explaining an erroneous insertion of a nozzle by a conventional inert gas filling method; and 
       FIG. 9  is a view explaining an erroneous insertion of a nozzle by a conventional inert gas filling method. 
     EXPLANATION OF REFERENCE NUMERALS 
     
         
         
           
             P . . . gas filling packaging machine 
             a . . . packaging bag 
             b . . . bag top c . . . fold 
             v . . . imaginary perpendicular line 
               4  . . . rotating body 
               9  . . . paired grips 
               21  . . . filling funnel 
               21   a  . . . drop mouth 
               23  . . . gas filling nozzle 
               23   b  . . . distal end 
               25  . . . nozzle attitude control unit 
               30  . . . roller 
               32  . . . cam plate 
               55  . . . inert gas supplying apparatus 
               65  . . . shutter unit