Manufacturing container or tube from paper; or other manufacturi – Bending – Folding
Patent
1996-08-02
1998-09-01
Hail, III, Joseph J.
Manufacturing container or tube from paper; or other manufacturi
Bending
Folding
493422, 493423, 493436, B31B 558
Patent
active
058003290
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to apparatus for folding sheet blanks, e.g. from carton or corrugated cardboard. The sheets are suitably prepared with slits and crease lines in order to form blanks, e.g. for boxes, trays and the like. Folding is carried out during continuous conveyance of the respective blank in the longitudinal direction of the apparatus. The blanks can be fed to the apparatus either via a separate feed unit or directly from the preceding unit in a production line. Folding is performed so that the side panels of the blank are folded upwards or downwards from the plane of the blank, folding being subsequently carried on until the side panels meet above or below the middle portion of the blank. The apparatus includes means with associated guide and drive means for conveying the blanks and folding in the side panels.
BACKGROUND ART
Apparatus performing folding operations of this kind on corrugated cardboard or carton are generally known in the paper industry.
Known apparatus for the kind of folding mentioned above, irrespective of whether folding takes place upwards or downwards, urges the side panels through a folding movement with the aid of rods, belts, compressed air, carve rollers, and/or vacuum. The elements acting on the side panels are either driven for accompanying the feed movements of the blank, or they are passive, so that the feed movement of the blank forces the side panels to fold together. In the case where the elements are driven, the object is to get the movement to coincide with the movement of a given point on the panel during the folding operation. Irrespective which of the principles mentioned is applied in the known apparatus, the movement does not coincide exactly with that of the side panels during folding, which takes place during conveyance of the blank. This signifies that movement occurs between the side panel and the element causing the folding movement, a friction force between the two then urging the panel in an undesired direction. This is one reason why the result of the folding operation is not always satisfactory with present folding apparatus. Other causes negatively affecting the folding result are poor or deviating crease lines, which steer folding so that the side panels are put together unevenly. The folding result is also affected by the material, and the orientation of the corrugations, if corrugated cardboard blanks are used. With present folding apparatus the result will often be that the folded side panels do not finish up in desired positions when put together, since in practice it will be the crease lines, possible folding rails and the composition of forces that decide the folding result.
When a side panel is folded inwards, independent of whether folding takes place upwards or downwards from the original plane, a given point on the panel describes an arcuate movement, if no account is paid to the feed movement of the sheet blank. The centre of this movement should lie in the upper or lower plane of the sheet, according to whether folding is upwards or downwards. If the feed movement is added to the described movement, an elongate, helical turning movement about this centre is obtained. Optimum for a folding apparatus would thus be to follow this turning movement in order to avoid any relative movement between a given point on the panel and a pressing element of the folding apparatus. The pressing element should also press perpendicular to the panel for obtaining the most favourable folding process.
The known apparatuses do not work according to this principle, consequently the above-mentioned relative movement has not been eliminated in them either. Many attempts have been made to attain an ideal movement, for example in the European patent no 0086153, relating to "A Machine for Folding Sheets". A turning movement in conjunction with the feed movement is indeed utilised in this machine, at the same time as the press elements used press substantially perpendicularly against the panels. However, the press elements are n
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Fager Lars
sberg Bengt
Day Christopher W.
Emba Machinery AB
Hail III Joseph J.
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