Patent Publication Number: US-2011072766-A1

Title: Bag forming, filling and sealing machine for preparing and filling tube-like bags

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of priority under 35 U.S.C. §119 of German Utility Model Application DE 20 2009 012907.1 filed Sep. 25, 20009, the entire contents of which are incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The present invention pertains to a bag forming, filling and sealing machine with a pull-off means for the packaging material, with a forming tube for forming and filling tube-like bags, with a longitudinal sealing means and with a cross sealing means, wherein the longitudinal sealing means is designed as an ultrasonic longitudinal sealing means integrated in the forming tube in order to seal first and second longitudinal edges of the packaging material into an overlapping sealing seam. 
     BACKGROUND OF THE INVENTION 
     Such bag forming, filling and sealing machines are used to produce and fill tube-like bags, which are used to package products, especially to package foods. Tube-like bags as a packaging have variable possibilities of use from economic and ecological points of view as well, because economical use of packaging material is guaranteed. 
     Various embodiments of bag forming, filling and sealing machines are known from the state of the art. Bag forming, filling and sealing machines are used, in general, to form a bag, which can then be filled with contents, preferably food, e.g., grated cheese or salad, especially with the use of a plastic film that can be sealed by introducing heat. To do so, a film is pulled off from rolls during the manufacture of such tube-like bags, led over a forming shoulder around a forming tube and transformed into a tube with overlapping longitudinal edges. The tube thus formed encloses a filling tube adapted to its shape. The overlapping edges are connected into a longitudinal seam by means of an ultrasonic sealing means and the tube is thus closed on the long side, as this is known from DE 10 2006 041 966 B3. An anvil is integrated in the filling tube in this document, and the anvil has guide sections, in which the longitudinal edges of the film, which are to be welded to one another, are guided. The guide sections are designed as grooves and are prepared in the anvil such that they overlap. The longitudinal edges of the film are thus guided in front of the welding site within the anvil such that they are sealed at the welding site such that they overlap each other. 
     A bottom seam is subsequently prepared with a first cross sealing means in such bag forming, filling and sealing machines. When the tube-like bag is filled via the filling tube, the tube-like bag is closed by a top seam prepared with a second cross sealing means. 
     The drawback of such bag forming, filling and sealing machines is that special films, especially with a predetermined thickness, which may consist of a plurality of layers, are also necessary for a sealed packing, and adaptation of the sealing means and of the introduction of heat must also be performed in case of different films or pieces. Depending on the nature of the films, these may, however, crease or wrinkle in the guide sections or fail to run in parallel already in front of the sealing means, so that overlapping guiding of the edges of the film is no longer guaranteed. The consequence of this is unsealed longitudinal seams. In particular, the prior-art ultrasonic sealing means is unable to produce sealed longitudinal seams as a result. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is therefore to provide a bag forming, filling and sealing machine, which has especially a better longitudinal sealing and achieves reliable sealing at high throughput. 
     This object is accomplished in a bag forming, filling and sealing machine of the type described in the introduction by the ultrasonic longitudinal sealing means having a spring-loaded guide plate for guiding the edges of the packaging material. 
     Provisions are made in an especially preferred embodiment for the ultrasonic or US longitudinal sealing means to have an anvil or a sonotrode, wherein this is fastened to a strap at the forming tube. The US longitudinal sealing means is integrated into the forming tube such that the forming tube has an elongated rectangular opening, in which the anvil is screwed in. Provisions are made here in a preferred embodiment for the anvil to have at least two vertical guide sections in the form of guide slots, through which the edges of the packaging material are led, wherein a first, especially inner guide slot of the anvil is provided with a slot between the sonotrode and an opposing part of the anvil relative to the sonotrode, especially flush with the outer edge of the forming tube and for a second, outer guide slot of the anvil to have a bulge arched into the guide section for guiding a second edge of the packaging material. 
     Optimal guiding of the edges of the packaging material is achieved by a spring-loaded guide plate being inserted in the outer guide slot and screwed to a guide sleeve around the forming tube, wherein the spring-loaded guide plate guides the second edge of the film from a second guide slot into the plane of the first guide slot onto the first edge. The spring-loaded guide plate is formed from an elongated, rectangular plate, a lower third being bent into a loop, so that a spring action develops under load. Depending on the bending of the loop of the spring-loaded guide plate, another spring force can be caused to be applied to the edge of the film. Provisions are preferably made for the spring-loaded guide plate to extend from an opening of the guide sleeve to a point in front of the sonotrode. 
     Provisions are made in an especially preferred embodiment for the pull-off means to have a forming shoulder, wherein a packaging material is to be clamped into the pull-off means. Furthermore, provisions are made for the forming tube to have a circular guide sleeve for guiding the packaging material below the strap and above the ultrasonic longitudinal sealing means, wherein the packaging material is held by the guide sleeve and the spring-loaded guide plate so close against the forming tube that stable and constant width of the longitudinal sealing seam is guaranteed and the edges of the packaging material are prevented from running apart. Furthermore, provisions are made for the longitudinal sealing means to have blowing nozzles for cooling the sealing seam, whereby the sealing of the longitudinal sealing seam can be additionally increased, because a cool seam has a higher tear resistance and hence can be stressed more heavily. For controlling the US longitudinal sealing means, provisions are preferably made for an electronic control unit to be associated with the US longitudinal sealing means. 
     Provisions are made in an especially preferred embodiment for the forming tube to have an inner cover for protecting the anvil protruding into the forming tube, the inner cover being essentially of a tubular design, wherein one side has a bulge arching rectangularly inwardly. It is thus guaranteed that contents dropping through the forming tube can pass over the anvil unhindered, without contents being able to be caught at same and to accumulate. Furthermore, the inner cover may be designed such that there is space to the side of the anvil for additional functionalities, e.g., electric leads, means for admitting gas to the product, dust removal means, etc. 
     Provisions are made in a preferred embodiment for an electronic control unit to be associated with the cross sealing means, which is likewise designed as an ultrasonic sealing means and has a sonotrode and an anvil. 
     A simplified bag forming, filling and sealing machine with a longitudinal sealing means with a flatly overlapping sealing seam by means of a compact ultrasonic means is made available by the present invention. Optimal guiding of the edges of the film web is guaranteed by the combination of the guide slots of the anvil with the spring-loaded guide plate and especially the guide sleeve around the forming tube. The edges of the film are completely prevented from running apart. Thus, not only does the bag forming, filling and sealing machine according to the present invention prepare reliable and tighter longitudinal seals, but also has a reduced overall height due to the compact design of the US longitudinal sealing means, which leads to faster packaging due to a smaller drop height of the products to be filled. 
     Further advantages and features appear from the claims and from the following description, in which an exemplary embodiment of the present invention will be specifically explained with reference to the drawings. The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings: 
         FIG. 1  is a perspective view of a bag forming, filling and sealing machine according to the present invention with a forming tube, a longitudinal sealing means as well as a cross sealing means; 
         FIG. 2  is an enlarged perspective view of the longitudinal sealing means with a spring-loaded guide plate; 
         FIG. 3  is a cross section through the longitudinal sealing means according to section A-A in  FIG. 4 ; 
         FIG. 4  is a vertical side view of a longitudinal sealing means with a cut-away part in the forming tube in the form of a vertical longitudinal section in the area of the longitudinal sealing means; 
         FIG. 5   a  is a side view of a spring-loaded guide plate according to the present invention; and 
         FIG. 5   b  is a front view of the spring-loaded guide plate according to the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the drawings in particular,  FIG. 1  shows a bag forming, filling and sealing machine  1  according to the present invention. It comprises a pull-off means  2  (shown only partially) for web-like packaging material, preferably a film, a forming tube  3  with a circular cross section, and an ultrasonic or US longitudinal sealing means  4  as well as a cross sealing means  5 . The direction of conveying is indicated by an arrow C from top to bottom. 
     The pull-off means  2  has a film unit  2 . 1 , which stores and feeds the film, as well as a forming shoulder (not shown), which is fixed at the forming tube and via which the film can be formed and pulled into a tube around the forming tube  3 . The forming shoulder has, in a manner known per se, a shoulder blade facing the film fed in with an essentially flat, horizontal intake area and encloses, in the direction of delivery of the film with downwardly directed legs, a filling tube of the machine for contents until it surrounds this as a sleeve having a shoulder on one side. Furthermore, the pull-off means  2  has a feed means (not shown) to feed the film tube. The feed means can be driven by a motor for this purpose. 
       FIG. 2  shows a perspective view of the bag forming, filling and sealing machine  1  according to the present invention in the area of the longitudinal sealing means  4 . The ultrasonic longitudinal sealing means  4  (US longitudinal sealing means) is fastened to a strap  3 . 1 , which is indirectly connected to the forming tube  3  and surrounds same at a radially spaced location. Furthermore, a guide sleeve  3 . 2 , which begins directly below the strap  3 . 1  and extends downwardly to below a sonotrode  4 . 2 , is formed around the forming tube  3 . The guide sleeve lays the film tightly around the forming tube  3  and feeds same under a downstream spring-loaded guide plate and, under said spring-loaded guide plate, overlappingly to the sonotrode  4 . 2 . The guide sleeve  3 . 2  is of an essentially tubular design and has a lateral opening  3 . 3  on the side facing the US longitudinal sealing means  4 . 
     There is a tubular intermediate space  3 . 2 . 1  for the film between the guide sleeve  3 . 2  and the forming tube  3 . The US longitudinal sealing means  4  is fastened to the strap  3 . 1 , which longitudinal sealing means has a sonotrode  4 . 2  next to an anvil  4 . 1 . Starting from the fastening to the strap  3 . 1 , anvil  4 . 1  is made L-shaped in the direction of the forming tube  3 , and an opposing part  4 . 1 . 1  of the anvil  4 . 1  made elongated downwardly towards the sonotrode  4 . 2  protrudes into the interior space of the forming tube  3 . Anvil  4 . 1  has a rectangular cross section, as it is shown in  FIG. 3 . Anvil  4 . 1  has two vertical guide sections in the form of guide slots, wherein a first, especially inner guide slot  4 . 3  of the anvil  4 . 1  is provided with a slot between the sonotrode  4 . 2  and an opposing part of the anvil  4 . 1  to the sonotrode, flush with the outer edge of the forming tube  3 . A second, especially outer guide slot  4 . 4  is formed at a certain distance in a plane parallel to the guide slot  4 . 3 . The guide slots  4 . 3 ,  4 . 4  extend approximately over two thirds of the width of the anvil, so that they overlap each other over somewhat more than one third of the width of the anvil  4 . 1 . This means that the longitudinal edges of the film laid around the forming tube  3  also overlap correspondingly. The edges of the film can be led through these guide slots  4 . 3 ,  4 . 4 . 
       FIG. 2  and  FIG. 4  show that the vertical longitudinal section of the outer guide slot  4 . 4  does not have a straight shape but a narrowing  4 . 5  arched towards the longitudinal sealing means  4 . A spring-loaded guide plate  6  is introduced into this outer guide slot  4 . 4 . 
       FIG. 5   a  shows the spring-loaded guide plate in a side view and  FIG. 5   b  shows it in a front view. The spring-loaded guide plate  6  is made of an elongated, rectangular plate, a lower part having a bend  6 . 2  of 180° with a finite bending radius, so that the lower third of the spring-loaded guide plate  6  forms a loop  6 . 3 . The spring-loaded guide plate  6  extends in its length from the top of the opening  3 . 3  of the guide sleeve  3 . 2  to a point just a short distance in front of the sealing area of the sonotrode  4 . 2 , the said loop  6 . 3  of the spring-loaded guide plate  6  pointing in the direction of the sonotrode. The spring-loaded guide plate  6  thus projects over the length of the outer guide slot  4 . 4  of anvil  4 . 1  vertically in both direction. Two screws  6 . 1  are provided at the upper end of the spring-loaded guide plate  6  to fasten the spring-loaded guide plate  6  to the guide sleeve  3 . 2 . The spring-loaded guide plate  6  is screwed flush to the edge of the opening  3 . 3  of the guide sleeve  3 . 2  under the strap  3 . 1  by means of the screws  6 . 1 . 
     The outer edge of the film is pressed by the spring-loaded guide plate against the inner edge of the film immediately after both edges emerge from the slots  4 . 3 ,  4 . 4  and hence both are pressed against the opposing anvil part  4 . 1 . 1  directly above the sonotrode  4 . 2 , so that the two edges lie directly one on top of another at the level of the sonotrode  4 . 2  between this and the opposing part  4 . 1 . and are reliably welded by the sonotrode over the said passing-through edge. 
     An inner cover  3 . 3 , which covers the anvil  4 . 1  protruding into the forming tube  3  (see  FIG. 3 ), is arranged within the forming tube  3 . The inner cover  3 . 4  is essentially of a tubular shape and the side facing the anvil  4 . 1  has a bulge  3 . 5  having a rectangular cross section in the form of the opposing part  4 . 1 . 1  of the anvil  4 . 1  within the forming tube  3 . The bulge  3 . 5  is beveled in the vertical extension in the upper area, the bevel extending from the forming tube  3  to the width of the opposing part  4 . 1 . 1  of the anvil  4 . 1 . The bulge  3 . 5  then extends in parallel to the opposing part  4 . 1 . 1  and ends under same at right angles. The length of the inner cover  3 . 3  is selected to be at least such that complete coverage of the opposing part  4 . 1 . 1  of the anvil  4 . 1  in the interior of the forming tube  3  is ensured, so that no contents can get caught at the anvil  4 . 1 . The inner cover  3 . 4  with the bulge  3 . 5  may, furthermore, be designed such that space is provided for additional functionalities, e.g., electric feed lines or other measuring means, to the side of the anvil  4 . 1 . Blowing nozzles (not shown), which are used to cool the sealing seam, are associated with the US longitudinal sealing means  4  in the lower area thereof. 
     Furthermore, a cross sealing means  5  (see  FIG. 1 ) is arranged under the US longitudinal sealing means  4 . This is also designed as an ultrasonic sealing means with an anvil  4 . 1  and a sonotrode  5 . 2 . Furthermore, an electronic control unit (not shown) is associated with the cross sealing means  5 . 
     The bag forming, filling and sealing machine  1  consequently carries out the following steps: 
     A packaging film is pulled off from a film unit  2 . 1 , for example, a film roll, and led over the forming shoulder around the forming tube  3 . The guide sleeve  3 . 2 , whose shape is adapted over the forming shoulder, guarantees a film laid tautly around the forming tube  3 , and the film lies within the intermediate space  3 . 2 . 1  between the guide sleeve  3 . 2  and the forming tube  3 . The edge-side inner sides of the film are sent further through the guide slots  4 . 3 ,  4 . 4  of the anvil  4 . 1  into the area of the longitudinal sealing means  4 , with a first edge of the film being led flush with the forming tube  3  through the inner guide slot  4 . 3 . A second edge of the film is led out of the intermediate space  3 . 2 . 1  into the outer guide slot  4 . 4 . The second edge of the film is meanwhile pulled between the narrowing  4 . 5  and the spring-loaded guide plate  6  arranged in the outer guide slot  4 . 4 . The spring-loaded guide plate  6  arranged in the outer guide slot  4 . 4  presses the second edge of the film onto the side of the guide slot  4 . 4  facing the forming tube  3  and thus forces fixed guiding of the second edge of the film. Depending on the bending of loop  6 . 3  of the spring-loaded guide plate  6 , a different spring force can be applied to the edge of the film. 
     The edges of the film are consequently placed overlappingly one on top of another and brought together into a so-called lap seal seam. The film guide plate  6  arranged in the outer guide slot  4 . 4  prevents the edges of the film from running apart. The edges of the film are sealed together by means of the sonotrode  4 . 2  and a flat, compact sealing seam is formed. Reliable guiding of the edges of the web is guaranteed by the guide slots  4 . 3 ,  4 . 4  of anvil  4 . 1  and of the spring-loaded guide plate  6 . The film tube is delivered farther downward by means of a feed means and closed to form a bag by the cross sealing means by means of a cross sealing seam. 
     The tube-like bag thus prepared is then filled with the contents dropping through the forming tube, preferably food, such as salad or grated cheese, etc., the inner cover  3 . 4  protecting the anvil  4 . 1  from contents dropping down. The filled tube-like bag is delivered in a next step farther downward and sealed at the open top end by a second cross sealing seam by the cross sealing means, so that the tube-like bag packaging is finished. 
     While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles. 
     LIST OF REFERENCE 
     
         
           1  Numbers  6  Spring-loaded guide plate 
           1  Bag forming, filling and  6 . 1  Screws sealing machine  6 . 2  Bend 
           2  Pull-off means  6 . 3  Loop 
           2 . 1  Film unit 
           3  Forming tube 
           3 . 1  Strap 
           3 . 2  Guide sleeve 
           3 . 2 . 1  Intermediate space 
           3 . 3  Opening 
           3 . 4  Inner cover 
           3 . 5  Bulge 
           4  US longitudinal sealing means 
           4 . 1  Anvil 
           4 . 1 . 1  Opposing part 
           4 . 2  Sonotrode 
           4 . 3  First, inner guide slot 
           4 . 4  Second, outer guide slot 
           4 . 5  Narrowing 
           5  US cross sealing means 
           5 . 1  Anvil 
           5 . 2  Sonotrode 
           6  Spring-loaded guide plate 
           6 . 1  Screws 
           6 . 2  Bend 
           6 . 3  Loop