WO1995023736A1

WO1995023736A1 - Method and apparatus for manufacturing, filling, and closing reclosable plastic bags

Info

Publication number: WO1995023736A1
Application number: PCT/SE1995/000187
Authority: WO
Inventors: Endre Joo
Original assignee: Endre Joo
Priority date: 1994-03-01
Filing date: 1995-02-22
Publication date: 1995-09-08
Also published as: SE9400698L; SE504739C2; AU1905695A; SE9400698D0

Abstract

The invention relates to a method and an apparatus for manufacturing, filling and closing of reclosable plastic bags formed of a bag blank (4) provided with a closing member extending along the entire blank in the shape of two mutually fitting groove and rib profiles (13a, 13b). The bag blank is, before and behind a filling station (II), advanced forward hanging in the pressed together groove and rib profiles (13a, 13b). The bag blank is before the filling station (II) provided with transverse joints (29), which end a short distance form the longitudinal closing member and define separate bags. Each of the groove and rib profiles is during the passage of the filling station (II) hanging separately and guided by each an arcuate path away from each other and back towards each other such that, the groove and rib profiles are reclosed at the top of the filled bags at the same time as the transverse joints are completed to and across the groove and rib profiles and the bags are severed.

Description

METHOD AND APPARATUS FOR MANUFACTURING, FILLING, AND CLOSING RECLOSABLE PLASTIC BAGS.

The invention relates to a method for automatic manufacturing, filling and closing of plastic bags according to the preamble of the following claim 1. The invention also relates to an apparatus for carrying through said method according to the preamble of the following claim 3.

Prior art illustrating this technical field is disclosed for example by the following patent specifications:

Automated machine disclosed by US 4 490 959. The machine is intended for transporting, opening, filling and closing the bags one at a time in a fully automatic way. The bags which are fed through the machine are connected together with one another in a chain. The machine is ideal for high-volume production. This machine has a very complicated design a.o. for the opening of the bag to be filled. The costs for such a machine will be high due to the complicated design. The high costs give cause for small entities having minor production need or a fluctuating production not to buy this machine.

The machine according to EP 0 249 868. This machine is intended for transporting, opening, filling and closing the bags hanging connected together with one another. They are mutually connected by connecting strips that are cut away after the operation. The system is simpler than the one described above. The machine can be operated manually, semi-automatically or fully automatically and, hence, is more suitable for small entities. Space demands are also smaller, and it is less expensive. The drawback of the system is that the costs for material becomes higher because an extra strip must be manufactured for the handling of the bags. Moreover, the handling mechanism becomes more complicated, partly due to the removing of the strips, partly due to the further handling.

An example of the type of bag blank that can be used in connection with the present invention is described in US 3 198 228. The material used, as starting material is a plastic film. The width of the plastic film is twice the height of the finished plastic bag. A short distance from the edges on the same side of the plastic film there are two longitudinal plastic profiles welded to the plastic film. The profiles are designed such, that if the film is double folded along the longitudinal centre line the profiles will be positioned opposite each other. If the profiles are pressed together they will interlock and form a tube looking like a sausage skin. The closing profiles can be opened again if the profiles are pulled apart. The material is delivered folded and rolled on a bobbin. In this condition the closing profiles are pressed together in locked state.

Manufacturing and handling of the reclosable plastic bags give rise to quite different handling problems than in case of bags for heat sealing. The main problem is that the bag must be opened and reclosed in a simple and reliable way in connection with the filling of the bag with fill material. There has been an endeavour to obtain a very uncomplicated system comprising a small number of movable details in order to reduce the costs and minimize the failure rates. This has, according to the invention, been achieved in that the method has obtained the characterizing features set forth in claim 1, and the apparatus for carrying through the method the characterizing features set forth in claim 3.

By the invention it has been achieved, that the bag blank, at least in the filling station, is hanging by the closing profiles, that the feeding motion takes place step by step by pulling the bag blank at the free end a bag width at each step, that the bags are formed in two steps by initially, before the filling, a portion of the blank is welded or in some other way is squeezed together laterally at the bottom portion of the blank, and in a second step all the side of the bag is welded after the filling and closing, and that the opening of the bag blank for filling is achieved solely by the pulling forward of the bag blank by means of guide rails with notches for the closing profiles, which guide rails surround the bag blank before and after the opening, with inner and outer arcuate guide rails, which each surround a half of the bag blank at the opening, and that advancing of the bag blank along the arcuate guide rails is enabled by the fact that the entire side of the bag is not welded at this operation.

Hence, the invention brings about that a method has been obtained which due to its simplicity has resulted in an apparatus with high reliability, fast feeding, few failure possibilities and low costs.

The invention will be more readily apparent from the following detailed description taken in conjunction with the accompanying drawings showing different embodiments of the apparatus according to the invention, and in which:

Figure 1 and Figure 2 are a side view and a plan view, respectively, of a first embodiment of an apparatus according to the invention, Figure 3 and Figure 4 are sectional views of a bag blank used in an apparatus according to the invention in open and closed condition, respectively, Figure 5A and Figure 5B show two projections of guide rails in sections I and III before and behind, respectively, a filling section II, Figure 6A and 6B show in two projections guide rails in section II, Figure 6C is a sectional view taken along line VTC-VIC in Fig. 6A, Figure 7 is a plan view showing the position of the guide rails, Figure 8A and 8B are two other projections of the guide rails in sections I and III,

Figure 9A and 9B are two other projections of the guide rails in section II,

Figure 9C is a sectional view taken along line IX C-IX C in Fig. 9A, Figure 10 and Figure 10A is a side view and a sectional view taken along line X A-X A, respectively, of the guide rails in sections I, II and III, Figure 11A and 11B are two projections showing a pull forward cylinder and a gripping member,

Figure 12A and 12B are two projections showing an alternative embodiment of the guide rails in sections I, II and III,

Figure 13A, 13B and 13C show the alternative embodiment of the guide rails in section II,

Figure 14A and 14B show the alternative embodiment of the guide rails in sections I and III,

Figure 15A and 15B show a further alternative embodiment of the guide rails, Figure 16A, 16B and 16C show the guide rails in Figs. 15A, 15B in section II,

Figure 17A and 17B show the guide rails in Fig. 15 in sections I and III, and Figure 18 shows the welding and cutting of the bag blank.

In Figs. 1 and 2 a bag blank 4 consisting of a plastic tubing is rolled on a bobbin journalled on a shaft 1. The plastic tubing is guided from the bobbin between guide rollers 2. The guide rollers 2, which are cylindrical and journalled in bearings, have a turned down notch. The object of the notches is to achieve an exact guiding of the groove and rib profiles of the plastic tubing and to prevent the plastic tubing from axial wandering between the rollers. The plastic tubing is guided from the rollers 2 along a guide member 3, which is divided into three sections:

Section I: its object is to support the plastic, keep it in correct position, and guide its movement. Section II: its object is to support the plastic, open the closing member and pull the side walls from each other to enable the filling operation. Section III: its object is to support the plastic and its content, and to lock the closing member.

The bag blank 4 may for example be designed as shown in Figs. 3 and 4, which show the bag blank in cross section. It is provided with pull flanges 15a and 15b and a closing member 13 consisting of locking profiles 13a and 13b, which match to each other. The locking or closing profiles can, as shown, comprise an essentially cylindrical part 13b, which fits in a corresponding cylindrical recess 13a. The profiles can have another design, essential for the function of the apparatus is, that the closing profiles 13a and 13b each have a considerably greater thickness than the thickness of the rest of the bag blank 4. The guide member 3 is composed of guide rails. The position of the guide rails and the movement of the plastic between the rails is shown in Fig. 7. The bag blank 4 is introduced into section I at the guide rail 1,16, is opened at the exit 20 of section I by the fact that section II is provided with a guide rail 17 to the right and a guide rail 18 to the left. Reclosing is achieved when the bag blank is guided into the guide rail 111,19 at its entrance 21.

The sections described here can be designed in different ways. In any case, however, the sections fulfil the basic demand to support the flexible hose and to open and reclose the closing member.

According to a first embodiment, see Figs. 5A-B, 6A-C, 10 and 10A, the sections of the guide member are designed as two rails positioned side by side. Between the rails a notch 22 is cut designed such, that it has room for the plastic film and its closing member. In order to permit the plastic film to slide easy between the rails the notch is made a bit larger than the actual closing member. The edges of the notches have to be chamfered to prevent the plastic film from being scratched. The rails only cover and guide the plastic hose a short distance beneath the closing member (about 5 mm) and above the closing member. See Figs. 5A-B, 6A-C. The notch 22 is cut in the surface of one 23a of two parallel plates 23a,23b. The notch 22 has a deep portion 22a adapted to the dimensions of the groove and rib profiles 13a,13b (see Fig. 3), and is ended with an upper portion 22b adapted to the pull flanges 15a and 15b, which may be reinforced. The notch 22 is narrow above and beneath the deep portion 22a in order to attain a good guiding of the closing member 13 in the deep portion 22a but also an easy sliding of the bag blank 4 in the notch 22. When the machine has run out of the bag blank 4 of plastic material a new bobbin is inserted. The plastic film has to be introduced between the guide rollers and the rails. The rails are situated in the very middle of the machine. It is difficult in this stage to introduce the plastic film between the rails because the space between them is limited and other machine parts are a hindrance. Hence, the guide rails, which are positioned in a row, are secured to a pull-out plate. In pulled-out position the guide rails become easily accessible outside the machine. In order to facilitate the introduction of the plastic film between the guide rails these are mutually displaceable. In the production stage the guide rails are kept together by screws. In connection with replacement of the plastic film bobbin the screws are unscrewed. The plates are separated by a spring which is located between them. Now the interspace is wide enough to permit the introduction of the plastic hose. After the introduction the plates are screwed together again and the package of guide rails are pushed back in position. The production can start.

Section I and section II are composed of two plates 23a,23b positioned side by side, see Fig. 8A-B. One of the plates is secured to a mounting plate. Two guide pins 24 extend through the plate and act as guides for the other plate. The plates are kept together by two screws 25. A pressure spring 26 is positioned between the plates and push the plates apart when the screws 25 are unscrewed.

Section II is composed of two pairs of rails. Each pair comprises two rails positioned side by side and are joined via a mounting plate, see Fig. 6A-C, 9A-C. The plates 23a,23b are curved in the horizontal plane with the concave sides turned towards each other. In this way an opening is formed between them through which the bags are filled. The constructive solution with guide pins and a spring is similar to that of section I.

It is not necessary that the guide rails, for their proper function, are designed as rails, as described above. They can be designed in different ways. The basic demand is that there is a longitudinal notch with a deep portion 22a in which the groove and rib profiles are accommodated, and that the arrangement can support the bag including its content and is rigid enough to press together the locking profiles. Accordingly, the rails can be replaced by pairs of rollers positioned with gaps in between or closely together, or as an alternative by a row of rollers on one side and a rail on the other side. See Figs. 12-17.

For a proper functioning of the machine the plastic hose has to be advanced step by step. This movement is accomplished by a feeding device 5, that pulls the plastic forward between the rails, see Fig. 11A-B. The length of each step corresponds to the width of the bag. When a finished bag is to be removed a portion of the plastic protrudes from the rails. A clamp member is moved towards the bag and grasps the bag. When it is verified that the bag is grasped the clamp member is moved in the axial direction of the plastic hose and pulls out the hose a distance corresponding to the width of the bag.

The clamp member comprises two fingers 27, which are journalled on a shaft 28. One side of each finger is stretched away from each other by a pneumatic cylinder 7. This results in that the other side of the fingers are clamped together and grasp the bag. The clamp member and its cylinder are secured to a mounting plate, which in turn is secured to another pneumatic cylinder, which performs the pulling action. The cylinder is permitted from rotating and is guided by two journalled shafts. The length of the cylinder stroke is adjustable.

Bag blanks according to the description above still have the shape of a plastic hose. To enable manufacturing and filling of the bags when going out from the plastic hose there is a demand that the sides are welded and the bags can be separated from each other.

The welding of the bag is complicated by the fact that a full welded side prevents the blanks frαn passing section II. As mentioned, above the object of this section is to open the bag. If the side of the bag is fully welded it is impossible to pull the sides from each other. Therefore the welding is performed by two steps with two separate pairs of welding jaws. In a first step 29 the sides are welded only partly, and in next step the welding is completed fully, see Fig. 18.

Step one: plastic blanks are welded together about four fifths of the length of the side counted from the bottom. The weld is made in vertical position. This weld 29 is made by the weld jaws 8 when the bag blank is between section I and II. The solution consists in that the side of the bag is welded before section II. Because the weld does not extend all the way up it gives a certain movability to the plastic and makes it possible to pass section II and bring about an opening. So in next working stroke this weld is moved over to the other side of section II. This means that a pocket is formed, beneath the filling opening. Now the bag can be filled through the opening.

As an alternative to the partial welding 29 the bag blank may be kept together here in another way during the filling operation, for instance by means of clamp jaws, until the welding of all the side is accomplished. In next working stroke the bag is moved a step and is closed. The sides are not yet completely welded.

Step two: the weld of the side of the bag should be completed, and at the same time the bag is severed frαn the other half-completed bags at the weld and separating station 30. The second pair of welding jaws 9 is located behind section III. It has to weld the rest of the bag and at the same time sever the bag frαn the other half-completed plastic bags. Alternatively the separating can take place after the completing weld by e.g. a cutting device.

The welding jaws are mounted in vertical position and mutually displaced in parallel away frc each other. The first pair of welding jaws 8 is positioned between section I and II, and the second pair behind section III. The jaws are secured to two carriages 10. Each carriage supports one half of the two pairs of jaws. The carriages are located one on each side of the plastic hose and are journalled on two parallel rails 11 by ball bearing guides 14. They are moved by two pneumatic cylinders 12 which are moving in a horizontal direction perpendicular to the advancing direction of the plastic hose.

The invention has been described with reference to some alternative embodiments of the invention. They should be considered only as examples of how the invention can be carried out and other embodiments are possible within the scope of the invention as stated in the accompanying claims.

Claims

C L A I M S

1. A method for automatic manufacturing, filling, and closing of reclosable plastic bags formed of a tubular bag blank (4) provided, with a closing member (13) extending along the entire blank in the shape of two mutually fitting groove and rib profiles (13a,13b), associated to each a side portion of the blank, that is arranged to be advanced hanging in the pressed together groove and rib profiles (13a,13b) of the closing member before and behind a filling station (II) , where the groove and rib profiles of the closing member temporarily are separated for forming a filling opening, characterized in that the bag blank (4), before the filling ^' operation, is provided with transverse joints (29), which end a short distance from the longitudinal closing member (13) and define separate bags, and in that, during the filling operation and the passage of the filling station (II) , each side portion is hanging in the associated groove or rib profile (13a or 13b, resp.) and guided in each an arcuate path away from each other and back towards each other, after which the transverse joints (29) after the filling operation are replaced or completed by transverse heat sealings (30), which extend to, and preferably across, the pressed together groove and rib profiles (13a,13b) of the longitudinal closing member.

2. A method according to claim 1, characterized in that the advance is effected step by step by pulling the free end of the blank, where separating of filled bags is performed.

3. An apparatus for carrying through the metod according to claim

1, in which the bag blank (4) is arranged to be advanced with the compressed groove and rib profiles (13a,13b) and adjacent portions of the two side portions of the blank running in a slot (22) provided with a notch (22a) for the groove and rib profiles, which slot is situated in a section (I) before and in a section (III) behind the filling station (II), which is provided with means (17,18) for temporarily separating the groove and rib profiles (13a,13b) of the closing member, characterized in that a closing device (8) is arranged, before the filling station (II) , to provide the bag blank with the bag forming transverse joints (29) ending a short distance frcm the longitudinal closing member (13) , in which filling station each of the groove and rib profiles (13a and 13b, resp.) together with adjacent side portions runs in an associated slot (22) provided with a notch (22a) for the groove or rib profile, which slots are situated each in an associated arcuate guide means (23a and 23b, resp.), which two guide means during the advance of the bag blank guide the groove and rib profiles (13a,13) into the notch (22a) of the following section (III) in the advancement direction, behind which a device (9) is situated for replacing or completing the transverse joints (29) by transverse heat sealings (30), which extend to, and preferably across, the compressed groove and rib profiles (13a,13b) of the longitudinal closing member.

4. An apparatus according to claim 3, characterized in that the arcuate guide means (17,18) as well as the further two sections (I,III) each comprise vertical plates (23a,23b), which are positioned in pairs side by side with the notched slots (22,22a) situated in at least one plate of each pair of plates (23a,23b).

5. An apparatus according to claim 3, characterized in that the arcuate guide means (17,18) as well as the further two sections (I,III) each comprise at least one row of rolls (Figs. 12-17) positioned close to each other and forming at least one of the side walls of the notched slots, which rolls are profiled to form a passage acting as the notched slot (22,22a)

6. An apparatus according to any of claims 3-5, characterized in that a reciprocating feeding device (5) provide:} with a gripping member

(6) that after a separating of a filled bag frαn the bag blank (4) is arranged to grip the free end of the bag blank and pull the blank a step forward corresponding to the width of a bag.