Device for manufacturing and filling plastic bags

Abstract

 Device for successively manufacturing and filling bags starting from a strip of weldable material, which device comprises a frame (1), a stock holder for a roll of the weldable material (M) supported by the frame, a standing filling tube (4) or supply of the product for packaging, folding means for the strip of material arranged at the top end of the filling tube, a heating element (7) arranged adjacently of the filling tube for forming a longitudinal seam in order to obtain a continuous tube of packaging material, and two clamping members (9) movable toward and away from each other with at least a pair of heating elements for forming in each case a transverse seam under the filling tube in order to obtain a bag, in addition to separation means for separating a filled and welded closed bag, wherein by each clamping member on either end of the heating element for the transverse seam is arranged an additional heating element (10) for arranging a weld seam which encloses an angle with the transverse seam, wherein a plate-like folding member can be carried between these clamping jaws in order to obtain a rectangular bag.

Description

[0001] The invention relates to a device for successively manufacturing and filling bags starting from a strip of weldable material, which device comprises a frame, a stock holder for a roll of the weldable material supported by the frame, a standing filling tube for supply of the product for packaging, folding means for the strip of material arranged at the top end of the filling tube, a heating element arranged adjacently of the filling tube for forming a longitudinal seam in order to obtain a continuous tube of packaging material and two clamping members movable toward and away from one another with at least a pair of heating elements for forming in each case a transverse seam under the filling tube in order to obtain a bag, in addition to separation means for separating a filled and welded closed bag.

[0002] Such a device offers the advantage that during manufacture the bags are also filled and that this can therefore take place in a continuous process. Filling takes place after a transverse weld has been arranged in the tube, whereafter the tube is fed through stepwise and another transverse weld can be arranged to close the bag. Finally, the filled bag can be severed. The drawback to such a formed bag is that the contents can remain behind in the folds of the corners close to the transverse welds, whereby the bag cannot be emptied entirely. This can be disadvantageous in the case of substances which have an impact on the environment.

[0003] The invention has for its object to provide a device wherein these "dead" corners are no longer present in the bags and the above stated drawback is therefore obviated.

[0004] The device according to the invention is distinguished in that by each clamping member on either end of the heating element for the transverse seam is arranged an additional heating element for arranging a weld seam which encloses an angle with the transverse seam, wherein a plate-like folding member can be carried between these clamping jaws.

[0005] Due to the arranging of the angular welds which connect onto the transverse welds the "dead" space in the corners is closed off, whereby none of the material in the bag can nestle in these corners. It is noted that the angular welds are arranged on either side of a fold of the bag, whereby a rectangular bag results. The stackability of the obtained bag is thereby improved.

[0006] In a further development the heating element for making the angular weld is embodied as a rotatably mounted stamp associated with each clamping jaw. Thus achieved in simple manner is that first the angular weld can be arranged and then the transverse weld, wherein the stamp can be rotated away during this latter welding operation. Overlapping welds can thus be applied, which enhances the closing action.

[0007] It is finally noted that the transverse weld, which forms the closing weld of the filled bag, can take a double form, wherein means can be provided for carrying the filled bag between these two parallel transverse welds.

[0008] The invention is further elucidated in the figure description of an embodiment hereinbelow. In the drawing:

fig. 1 shows a perspective view of the device according to the invention with partly broken away parts for the purpose of elucidating the operation of the clamping jaws,

fig. 2 is a perspective view of a part of the formed bag which is embodied with angular welds,

fig. 3 is a perspective view of the clamping jaw with heating elements according to the invention for making transverse and angular welds,

fig. 4a, b, c show the successive steps in the welding operation, that is, arranging of the transverse and angular welds,

fig. 5 is a perspective view of the folding plate in co-action with the stamps for making the angular welds,

fig. 6 is a perspective view of an alternative embodiment of a formed bag with carrying grip and angular welds.

[0009] Designated in fig. 1 with the numeral 1 is the frame of the device which can be constructed randomly and comprises for instance a housing 2 in which diverse control systems are accommodated.

[0010] Fixed to the housing is a reel 2 onto which is pushed a roll of weldable material M. Via a wind-off system 3 which otherwise falls outside the scope of the invention the strip of material is carried to the top end of the filling tube 4 suspended in the frame 1. The filling tube hangs vertically and is embodied on the top part with a funnel-like collar 5 onto which can be connected a filling system for the material for packaging.

[0011] The underside of filling tube 4 hangs free and ends some distance above a box-like part 6 of the frame in which are received welding elements which are further elucidated hereinbelow.

[0012] Close to the top end of filling tube 4 are arranged folding means 4' for guiding the strip of material M and folding thereof round the filling tube so that a tube-shaped semi-manufacture is obtained which connects close-fitting along the outer wall of filling tube 4.

[0013] A first heating element is placed on the front side of filling tube 4 for bringing about the longitudinal seam of the tube round filling tube 4. The operation of this heating element 7 is assumed known and is not elucidated further. It is noted that in each case the strip of material is pulled down stepwise by means of an endless conveyor device 8 on either side of filling tube 4, during which movement the heating element 7 retracts slightly. The weld can then be applied at each stand-still.

[0014] It is likewise known to arrange in the box-like frame part 6 heating elements 9 in the form of clamping jaws movable away from and toward each other which are each provided with heating elements to enable arranging of a transverse weld under the filling tube 4 over the full width of the tube. Thus are created a lower transverse weld O and an upper transverse weld B which together with the longitudinal weld L form the total bag which has meanwhile been filled by pouring material downward via filling tube 4. The obtained bag is subsequently severed from the bottom end of the tube, whereafter the following cycle can take place. It will be apparent that manufacture and filling of the bags can take place continuously.

[0015] According to the invention an angular weld H, which is shown in enlarged detail in fig. 2, is arranged in each case in addition to the transverse welds O, B.

[0016] This angular weld serves to close off the fold in the material close to both ends of transverse weld O, so that no material that is poured into the bag can enter the portion K thereof.

[0017] When folded outward after filling of the bag these angular welds H form together with the respective transverse welds O and B a bottom boundary, which gives the bag a rectangular shape.

[0018] There now follows a description of the arranging of the angular welds H by means of additional heating elements at the clamping jaws 9 in fig. 1.

[0019] The box-like frame part 6 contains the clamping jaw 9 as well as four stamp-like additional heating elements 10 associated therewith. Clamping jaw 9 has on the front side heating elements 11 between which is arranged a separating member 12 which can be of random type, for instance a serrated knife strip. Heating elements 11 provide the upper and lower transverse welds which are mutually separated thereafter by separating member 12.

[0020] Clamping jaw 9 is reciprocally slidable in the direction of arrow P1 between a number of supports 13 which are fixedly attached in the box-like frame part 6. Clamping jaw 9 is reciprocally movable between the supports 13 by means of two cylinders 14 supported by the box-like frame 6. The cylinder rods press against a profile 15 which is mounted pivotally on shaft 15'' via arms 15'.

[0021] Arranged behind profile 15 is a support plate 16 to which are fixed sleeves 17 in which the shafts 18 of the stamp-like additional heating elements 10 are mounted rotatably and slidably. The sleeves 17 extend above and below clamping jaw 9 and all run mutually parallel. The upper and lower stamp 10 are mutually coupled in each case at the rear by a rotating mechanism 19 consisting of an arm 20 fixedly attached to shaft 18, which arms have mutually opposing directions. The outer ends are connected by a coupling strip 21. By rotating the shafts 18 by means of a cylinder 22 which engages on the upper shaft 18 via a pivoting lever 23, a rotation of the stamps 10 located one above the other is effected, which rotation proceeds in opposing directions and synchronously by means of the mechanism 20, 21. The stamps 10 are shifted reciprocally in sleeves 17 by means of a cylinder 24, the rod of which is connected to a bridge piece 25 which engages on the rear ends of shafts 18.

[0022] It is noted that a plate-like folding member 26 can be carried in front of the stamps and retracted again therefrom in the direction of arrow P2.

[0023] The operation of the above mentioned mechanism is as follows and is elucidated in fig. 4a, b and c. The material M for welding is shown in cross section in the figures and is situated between clamping jaws 9 and stamps 10. The latter are placed here in the pushed forward position in relation to the clamping jaws 9 and thus protrude beyond clamping jaws 9. The plate-like folding member 26 is situated in the retracted position.

[0024] Fig. 4b shows that the plate-like folding member 26 is pushed inward as according to arrow P2 so that a fold is made in the material M. The stamps 10 are subsequently slid toward one another in the direction of arrow P3 and through supply of heat the material situated between the two layers of the material M will mutually adhere. Not all four layers are welded in this way because of the presence of the plate 26.

[0025] After sufficient welding of the material the stamps 10 are then retracted and rotated as according to fig. 4c so that the stamps will be situated above and below clamping jaws 9. At that moment the clamping jaws 9 can be pushed toward one another as according to arrow P4 and a transverse weld can be arranged over the full width of the material M, but not after the plate 26 has been shifted back in the direction of arrow P2'.

[0026] Various matters are further elucidated in perspective in fig. 5. When the welds are arranged by means of stamps 10 the angular weld H results, each of which encloses a determined angle with the horizontally running transverse weld O, B to be further applied as shown in fig. 5. It is noted that angular weld H runs mirror-symmetrically relative to this transverse weld.

[0027] Other angular welds are of course possible within the scope of the invention. The angular weld H does not for instance have to follow a straight line but may also have a determined curvature. The size of the angular weld H, that is, the overlap with transverse welds O, B, can also be chosen at random due to the disposition of the rotatable stamps 10. Each stamp can also make an angular weld H having a bent shape so that for instance a connecting weld as designated with H' can be made between the upper and lower angular weld H.

[0028] Finally, fig. 6 shows an embodiment wherein the upper weld is embodied as a double transverse weld B', B'', the welds being arranged at a mutual distance. Between these welds can be arranged holes 30 which serve to receive fingers to enable carrying of the bag Z by means of the protruding neck Y. Arranging of the angular welds H takes place in the manner described above.

Claims

1. Device for successively manufacturing and filling bags starting from a strip of weldable material, which device comprises a frame, a stock holder for a roll of the weldable material supported by the frame, a standing filling tube for supply of the product for packaging, folding means for the strip of material arranged at the top end of the filling tube, a heating element arranged adjacently of the filling tube for forming a longitudinal weld in order to obtain a continuous tube of packaging material, and two clamping members movable toward and away from each other with at least a pair of heating elements for forming in each case a transverse seam under the filling tube in order to obtain a bag, in addition to separation means for separating a filled and welded closed bag, characterized in that by each clamping member on either end of the heating element for the transverse seam is arranged an additional heating element for arranging a weld seam which encloses an angle with the transverse seam, wherein a plate-like folding member can be carried between these clamping jaws.

2. Device as claimed in claim 1, characterized in that the or each additional heating element is embodied as a stamp rotatably mounted in the associated clamping jaw.

3. Device as claimed in claim 2, characterized in that cutting members are placed in the clamping jaws between in each case two heating elements for parallel transverse seams arranged at a mutual distance.

Drawing