US3165035A

US3165035A - Method for continuous tube producing

Info

Publication number: US3165035A
Application number: US147793A
Authority: US
Inventors: Stark Sven Olof Soren
Original assignee: Individual
Current assignee: Individual
Priority date: 1960-10-28
Filing date: 1961-10-26
Publication date: 1965-01-12
Anticipated expiration: 1982-01-12

Description

Jan. 12, 1965 s. o. s. STARK 3,165,035

METHOD FOR CONTINUOUS TUBE PRODUCING Filed Oct. 26. 1961 INVENTOR AT TORNEYS- United States Patent This invention relates to a method of forming from a flexible but relatively buckling-stiff web a continuous tube having a longitudinal seam parallel to the tube axis.

From e.g. the US. Patent No. 2,832,271 an apparatus is known for producing a continuous tube of this type from a flat web of a flexible but relatively buckling-stiff material. In this apparatus the web is gradually converted from its fiat stage into tube form by means of substantially external tube forming means, and its longi tudinal edges are joined into a longitudinal seam parallel to the tube axis.

Since the web is presupposed to be relatively bucklingstifI" and thus scarcely elastic, a considerable forming length is required in order to convert the web from fiat into tubular shape without inconvenient crease lines, cracks or ruptures. In order that tension dilferences owing to differences in the generatrice lengths in different points along the web width be avoided an infinite forming length theoretically would be required. Owing to the fact that the web material in spite of its relatively buckling-stiffness or springiness nevertheless has a certain limited ability to absorb and equalize tension variations, theforming length may be reduced to a finite value.

In several cases, however, a forming length of a practical finite value is a definite drawback, since it requires a considerable space for the forming apparatus. The drawback is especially apparent for such packaging machines, in which the tube is supplied with filling material through its trailing end and is flat pressed along narrow transverse zones to divide it into filled and sealed packages. As far as the filling operation is concerned, the tube must be produced in substantially vertical position having its trailing end uppermost, which moreover also is apparent from the above mentioned US. patent. This gives rise to an essentially total height of the packaging machine with requirements on corresponding ceiling height in the room, where said machine is located.

By the method in accordance with the invention a means to avoid the above mentioned drawbacks is indicated. This means implies that the tube forming course is divided into three phases, viz, two forming phases with a connecting web guiding phase. In the first forming phase, thus, the fiat Web is double folded substantially along its longitudinal central line with the web side corresponding to the inside of the tube turned inwards. In the guiding phase the double folded Web is carried over a pulley drum or a similar guiding surface having such as relatively large bending radius that in relation to the longitudinal direction of the web transverse crease lines or cracks in the web material along the central web crease substantially are avoided. In the final forming phase the double folded Web is formed into a tube having a substantially circular cross section at the same time as both of its longitudinal edges are joined in a longitudinal seam parallel to the tube axis.

Because of this improved method, it is possible to double fold the web While the web is traveling upwardly from a supply roll and then to convert the double-folded Web into a cylindrical form while the tube is traveling downwardly. Thus, the height of the forming apparatus when forming a vertical tube may be considerably reduced in relation to the above mentioned conventional tube forming method.

In the following the invention will be described in 3,1h5fi35 Patented Jan. 12, 1965 greater detail reference being made to the accompanying drawing, in a schematic perspective view illustrating the method in accordance with the invention applied to the production of filled and sealed tetrahedron-shaped packages.

From a supply roll 1 a web 2 packaging material is rolled off, which web e.g. may consist of a relatively thick paper web, whose one side has a covering, relatively thinner coating layer of a heat-scalable plastic material, e.g. polyethylene, while its other side has a still thinner coating layer of wax or plastic material. The web 2 is first carried over a web tension adjustiug,'spring loaded flap 3 to a guide roller 4 in order thereafter to be carried under web positioning pulley roller 5 parallel to roller 4 and against which the thicker coating layer of the web 2. engages. From the pulley roller 5 the web 2 is carried upwards substantially vertically in doing which it is first gradually double folded, substantially around its longitudinal central line and carried between two co-operating clamping rollers 6 and '7 having their mutually parallel axis substantially perpendicular to as well the longitudinal direction of the web 2 as the pulley roller 5. In the space between the clamping rollers d and 7 the double folding of the web 2 is performed, and therefore the web 2 leaves this space in a flat, double folded state and is carried up and over a pulley drum 8 located at a distance above the clamping rollers 6 and 7 and rotatable on an axis parallel with axis of rollers 6, '7. Between the pulley drum 8 and the space of the clamping rollers the double folded web 2' is guided laterally by means of three peripherically grooved discs 9, l0 and 11 having their axis substantially perpendicular to the side plane of the web and with their peripherical grooves engage the respective longitudinal edges of the double folded web 2.

The pulley drum 8 has such a relatively large radius that in relation to the longitudinal direction of the web transverse crease lines or cracks in the web material along the central web crease substantially are avoided. These crease lines or cracks are not only aesthetically disfigurating for the final tube, but involve furthermore a risk for ruptures in the web material, which ruptures could be fateful, if for instance the tube should form the walls in a package intended for liquids.

From the pulley drum 8 the double folded web is carried substantially horizontal to a similar pulley drum 12, whose axis is parallel to the first mentioned pulley drum 8. Over the second pulley drum 1?. the web 2 is so guided that it leaves the drum 12 substantially vertically downwards.

Immediately below the drum 12 the gradual forming of the double folded web 2 into the desired tube 13 thereafter follows. Encircling but not engaging against a substantially vertical filling pipe 14 the web 2 is carried into a horizontal forming ring 15 having a shape corresponding to the desired cross sectional shape of the tube 13 to be formed at a corresponding level below the other pulley drum 12.

At some distance below the tube forming ring 15 there is a longitudinal sealing element 16 with an external joint pressure roller 17. The sealing element 16 seals together thetwo overlapping edges of the web 2 which have been brought together by the tube forming ring 15, and an external pressure roller 17 in cooperation with an internal pressure roller, not illustrated, located within the tube and supported by the filling pipe 14 completes the longitudinal seam of the tube 13.

In the present case the sealing element 16 is suitably in a bracket i3 by means of a projecting arm 19 from the filling pipe 14 between the web edges separated into a slot at this level. The supplying pipe 26 to the filling pipe 14 is consequently also carried through the above mentioned slot.

For the downwards directed feeding of the continuously produced tube 13, but in the first place for dividing the tube 13 into filled and sealed packages below the pressure roller 17 and in the extension of the tube there are two yokes 21 and 22 along the tube axis and by means of guide bars 23 and 24, respectively, these yokes are displaceable in a reciprocating manner, the one yoke 21 inside the other yoke 22. The yokes 21 and 22 each support a pair of cooperating clamping jaws (not shown). The pairs of clamping jawsare arranged to flat press the tube l3 along relatively narrow transverse zones in relation to the tube axis and by heating the inside of the plastic layer in these zones to divide the tube 13 into filled and sealed packages. In the actual case both pairs of clamping jaws are intended to flat-press and heat-seal the tube 13 in mutually, substantially perpendicular planes in order to produce tetrahedron-shaped packages. Furthermore each of the pairs of clamping jaws is provided with knife-means or the like being arranged by a transverse cut in each of the transverse sealing zones to separate the transversely sealed finally closed package from the next-following one.

When functioning, both yokes 2i and 22 are driven by a common drive (not shown) also attending the operation of the pairs of clamping jaws. The yokes 21 and 22 are moved in dependence on the drive in such a way that one is carried to its uppermost point, while the other moves downwards with its pair of clamping jaws in engagement with the tube 13 thereby carrying same, i.e. winding oil a corresponding length of the web 2. from the supply roll 1. When the downwards moving yoke has reached its lower position, the upwards moving yoke has reached its uppermost position, by the drive and its pair of clamping jaws is brought into engagement with the tube 13, while the pair of clamping jaws of the lower yoke releases same, etc.

In timed relationship to the tube feeding, i.e. the production of packages, the filling material is supplied to the inside of the tube 13 to be formed through the supplying pipe 20 and the filling pipe 14. The supply of filling material can for instance be performed by means of a charging pump driven by the above mentioned drive or the like.

In order that the tube forming be effected substantially without stresses and independent of the tension variations induced by the simultaneous tube feeding and package forming the pulley drum is suspended in one end of a bail 25 the other end of which is pivotable about a pivot (not shown) parallel to the axis of the drum 12. By coupling means (not shown either) the bail 25 is connected to the drive of the apparatus in such a manner that the drum 12 will in timed relationship to the intermittent downward tube feeding swing downwards a distance substantially corresponding to the advance stroke, thereafter to swing upwards again and thereby eiiect a corresponding advance of the web 2 from the supply roll 1.

Thus, the invention makes possible a division of the tube forming operation into two tube forming steps proper with an intermediate web guiding or deflecting step. For that reason the tube forming operation no longer need be carried out completely along the tube axis or the extension thereof but the first tube forming step may be transferred to another part of the space, e.g. parallel to the other tube forming phase but of opposite direction in relation thereto as described above and shown in the drawing.

I claim:

In the method of forming a continuous tube having a longitudinal seam parallel to the tube axis from a continuous web of flexible but relatively buckling stiff material, the steps which comprise firstly moving the web upwardly and simultaneously double folding the web substantially along its longitudinal central line into a generally fiattened state with the side of the web corresponding to the inside of the tube facing inwards, guiding said double folded web in said flattened state through a path including a relatively large bending radius to establish a movement of the Web in a downward direction, forming said downwardly moving double folded web into a tube of substantially circular cross section and joining the opposite longitudinal edges of said tube to establish a seam extending longitudinally of the tube axis.

References Cited in the file of this patent UNITED STATES PATENTS 2,113,658 Lasko Apr. 12, 1938 2,237,119 Smith Apr. 1, 194i 2,326,931 Dalton et a1 Aug. 17, 1943 2,346,044 Nadeau Apr. 4, l944 2,832,271 Iarund Apr. 29, 1958