Device for controlling tension in a web of packaging material

Abstract

An arrangement for controlling longitudinal forces acting on a web of packaging material being wound from a first reel to a second reel, said arrangement comprising a first roller having a first rotational axis and a second roller having a second rotational axis, wherein the first rotational axis is fixed while the second rotational axis is movable.

Claims

1. An arrangement for controlling longitudinal forces acting on a web of packaging material being wound from a first reel to a second reel, said arrangement comprising: a first roller having a first rotational axis and a second roller having a second rotational axis, the first rotational axis being fixed while the second rotational axis is movable, the second rotational axis being arranged on a first side of the first roller, the first and second rollers not being in contact, the second rotational axis being movable along a rectilinear and a circular path such that the second roller is movable to a second side of the first roller, the second side of the first roller being opposite the first side of the first roller.

2. The arrangement of claim 1, wherein the circular path comprises a segment of a circular arc.

3. The arrangement of claim 2, wherein a central point of the circular arc coincides with the first rotational axis.

4. The arrangement of claim 3, wherein a radius of the circular arc corresponds to about a sum of a radius of the first roller and a radius of the second roller.

5. The arrangement of claim 3, wherein a radius of the circular arc corresponds to about a sum of a radius of the first roller a radius of the second roller, and a thickness of the web of packaging material.

6. The arrangement of claim 1, wherein the rectilinear path has an extension along a radius extending from the first rotational axis.

7. A web processing line that subjects a web of packaging material to processing steps, the web processing line comprising the arrangement of claim 1, wherein the web of packaging material is configured to, in a threading position, follow a rectilinear path between the first and second rollers, while in an operative position the web of packaging material is arranged to engage with the first and second rollers, wherein a switch from the treading position to the operative position is enabled by the movement of the second roller along the rectilinear path and the circular path.

8. The web processing line of claim 7, wherein the web processing line is a web doctoring line.

9. A method for controlling longitudinal forces acting on a wed of packaging material being wound from a first reel to a second reel, comprising arranging a second roller on a first side of a first roller while the first and second rollers are not in contact with one another, the first roller being rotatable about a first rotational axis and the second roller being rotatable about a second rotational axis, arranging the web of material to follow a rectilinear path passing between the first roller and the second roller while the first and second rollers are not in contact with one another, translating the second rotational axis along a rectilinear path and along a circular path to move the second roller to a second side of the first roller that is opposite the first side of the first roller.

10. An arrangement forming part of a machine that processes a web of packaging material to control longitudinal forces acting on the web of packaging material as the web of packaging material is fed along a path from a first reel to a second reel, the arrangement comprising: a first roller rotatable about a fixed first rotational axis; a second roller rotatable about a movable second rotational axis that is movable along a roller path spaced from the first rotational axis; the second roller being movable along the roller path: i) from an operative position in which the second roller is in engagement with the first roller and the web is in contact with and guided around a portion of the first roller and a portion of the second roller to an engagement position in which the second roller is in engagement with the first roller and the web passes between the first and second rollers; and ii) from the engagement position to a thread position in which the second roller is disengaged from the first roller and the web passes between the first roller and the second roller.

11. The arrangement of claim 10, wherein a part of the roller path is an arcuate roller path.

12. The arrangement of claim 11, wherein the arcuate roller path is a circular arc possessing a rotational center that coincides with the first rotational axis.

13. The arrangement of claim 10, wherein the roller path includes a first part along which the second roller moves from the operative position to the engagement position and a second part along which the second roller moves from the engagement position to the thread position, the second part of the roller path being rectilinear.

14. The arrangement of claim 13, wherein the second part of the roller path that is rectilinear is positioned along a radius extending from the first rotational axis.

15. The arrangement of claim 13, wherein the roller path includes a first part along which the second roller moves from the operative position to the engagement position and a second part along which the second roller moves from the engagement position to the thread position, the first part of the roller path being a circular arc.

16. The arrangement of claim 15, wherein the circular arc possesses a rotational center coinciding with the first rotational axis.

17. The arrangement of claim 10, wherein the roller path includes a first part along which the second roller moves from the operative position to the engagement position and a second part along which the second roller moves from the engagement position to the thread position, the first and second parts of the roller path possessing different shapes, the first part of the roller path being a circular arc.

18. The arrangement of claim 17, wherein the circular arc possesses a rotational center coinciding with the first rotational axis.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) All drawings are schematic drawings having the purpose of illustrating the operational principle of the present invention.

(2) FIG. 1 is a side view of a doctoring line having a pull and brake arrangement according to a first embodiment of the present invention, in a winding mode thereof.

(3) FIG. 2 is an isolated sideview of a pull and brake arrangement according to a first embodiment

(4) FIG. 3 is a side view of a doctoring line having a pull and brake arrangement according to a first embodiment of the present invention, in a threading mode thereof.

(5) FIG. 4 is a side view of a doctoring line having a pull and brake arrangement according to a first embodiment of the present invention, in a wasting mode thereof.

(6) FIG. 5 is a detailed view of the pull and brake arrangement in the mode of FIG. 1.

(7) FIG. 6 is a detailed view of the pull and brake arrangement in the mode of FIG. 3.

(8) FIG. 7 is a detailed view of the pull and brake arrangement in the mode of FIG. 4.

(9) FIG. 8 is a detailed view of a pull and brake arrangement according to prior art.

DETAILED DESCRIPTION

(10) A doctoring line 100 is shown in FIG. 1. The doctoring line has a first rotational shaft or reel 102 and a second rotational shaft or reel 104. A web of packaging material 106 is wound from the first reel 102 to the second reel 104, and in a doctoring station indicated by the rectangle 108 potential defects may be removed in a suitable manner. How the doctoring is performed will not be discussed in detail in the present disclosure, but for the small contribution that may be enabled by some embodiments of the present invention.

(11) The present pull- and break arrangement 110 comprises a first roller 112 and a second roller 114, both being arranged to rotate around a first rotational axis 116 and a second rotational axis 118 respectively. During a doctoring process the operative position of the arrangement 110 is such that the web is guided along an S-shaped path through the arrangement. In the present setup the first roller 112 is arranged above the second roller 114. The web is guided below and around about half the second roller on the far side thereof, as seen from the first reel 102 before following the second roller around about half its circumference before continuing towards the doctoring station and the second reel.

(12) A path of the web upstream the arrangement 110 and downstream thereof is such that if it was not for the second roller 114 the web would pass on a first side of the first roller while the second roller 114 is, in the operative position, is arranged on a second side of the roller, opposite to the first, thus enabling the S-shaped path.

(13) The rotational axis of the first roller 112, the first rotational axis 116, may be statically arranged, while the rotational axis of the second roller 114, the second rotational axis 118 may be movably arranged. The movement of the second rotational axis, i.e. the movement of the second roller, will be described referring to the detail view of FIG. 2.

(14) FIG. 2 illustrates the first roller 112 in full lines while various positions for the second roller 114 are shown in dotted lines. There is a position P1 corresponding to the position as shown in FIG. 1; an operative position. There is a position P2 which corresponds to an engagement position which is more of a position passed when moving between the other positions. There is a waste position P3 in which the arrangement will guide a passing web downwards. There is also a thread position in which the second roller 114 is fully disengaged with the first roller 112 such that a web may be conveniently arranged (or thread) through the arrangement 110 merely by following a rectilinear path. The first roller 112 is arranged to rotate around a first axis 116 and has a radius R1. The second roller 114 is arranged to rotate around a second axis 118 and has a radius R2. The first and the second roller are arranged in parallel, having parallel rotational axes. In one or more embodiments both rollers are suspended from one side axial thereof only, basically corresponding to the rotational axis of each roller having one end attached to a constructional arrangement while the second end is free.

(15) Returning to FIG. 2 the second roller is movably arranged, such that it may be rotated from position P1 to position P2 merely by allowing for the second rotational axis to follow an arcuate path 120, i.e. a segment of a circular path. From position P2 the second roller may be rotated further to position P3, or it may be moved in a rectilinear direction along a rectilinear path 122 to position P4.

(16) One convenient way of enabling such motion pattern is to arrange one end of the second roller on a sled (not shown) configured to perform a translational motion along a rectilinear direction on a plate or rail, which in turn is arranged to rotate around a rotational axis. The translational motion may be conducted by a servomotor, with a pneumatic cylinder a hydraulic cylinder, or with any other suitable arrangement. The rotational motion of the plate or rail may be conducted with any suitable drive, either acting directly on the rotational axis or on indirectly via a suitable linkage. It is readably understood how such an arrangement could enable the motion pattern has shown in FIG. 2. The movement is simplified if the rotational axis of the plate or rail coincides with the first rotational axis. The radius R3 of the path along which the second roller is moved corresponds to the sum of the radius R1 of the first roller and the radius R2 of the second roller, at least to a decent approximation. However, in a situation where the first roller is to be moved from the first position P1 to the fourth position P4 the radial movement may be performed prior to the rotational motion giving another radius.

(17) A drive enabling the translational motion of the second axis may also be used to vary a force with which the second roller is pressed towards the first roller.

(18) FIG. 3 is a view illustrating the position of the second roller in a threading operation, i.e. when a free end of a web of packaging material is to be guided through the doctoring arrangement and the pull- and break arrangement in particular, for the first time. Prior to threading the second roller is moved to position P4. When arranged in position P4 it will be possible to pull the web of packaging material through the arrangement along a rectilinear path. It is readily understood that if the second roller would have been in the operative position P1 the manoeuvre of threading would be more cumbersome. After the web has been pulled through the arrangement the second roller may be moved to position P2, clamping the web between the first and second roller. Thereafter the second roller may be rotated down to the operative position P1, thus concluding the threading operation.

(19) In the view of FIG. 4 the second roller has been arranged in the waste position P3. In this position the second roller is in contact with the first roller, with the intermediate of the web 106, and the tangent of the contact is directed downwards, enabling guiding of the web in an alternative direction. In the present embodiment the web is directed towards a waste assembly schematically indicated by the recycling bin. Wasting of packaging material may be the first operation after threading of a web. This means that the first roller is moved from the position P4, to position P2, and then to the waste position P3. One other example could be that the second roller is moved from the first position P1 directly to the waste position P3. No matter the scenario the present arrangement nevertheless enables the second roller to assume the position P3.

(20) Some features as associated effects have been described in the detailed description, referring also to the drawings. The description has been detailed, but it should still not be construed as limiting to a general concept of the invention as defined by the appended claims. The skilled person will, from the enabled embodiments and the associated description, be able to construct new embodiments vis--vis the embodiments being having been described without departing from the scope of the appended claims.