GB2263486A

GB2263486A - Producing corrugated sheets

Info

Publication number: GB2263486A
Application number: GB9200699A
Authority: GB
Inventors: William H Stephens
Original assignee: LOSCOE Ltd
Current assignee: LOSCOE Ltd
Priority date: 1992-01-14
Filing date: 1992-01-14
Publication date: 1993-07-28
Anticipated expiration: 2012-01-14
Also published as: BE1003743A6; GB9200699D0; GB2263486B

Abstract

Corrugated board is produced by bonding an inner liner web to a corrugated intermediate web in a single facer 3 or 27. A second outer liner web is then applied in a double facer 16. A web of corrugated board 6 or 31 is then directed upwardly to a rotary shearing station 35 for cut-off as required, at the end of an order run. The web 6 or 31 is then directed upwardly to one of two streams which are led upwardly to a double level cut-off knife 45 which forms sheets cut to a desired size. The cut sheets are delivered to upper or lower stacking stations 50, 51 where they are downstacked on beds which are lowered and stacked sheets are led along roller conveyors to a mobile trolley. Any sheets 109 which are warped are passed between a pair of backing rollers 110, 111 and an adjustable bending roller 115 is urged downwardly against the bow of the sheet 109 to correct the warp. Dust generated in the cutting step is removed by ionising dust particles, vibrating the particles and removing them by vacuum. <IMAGE>

Description

"A Process for Producing Sheet Naterial" The invention relates to a process for producing sheets of corrugated paperboard material.

Corrugated paperboard used in the manufacture of boxes is made up of paper sheets. Double faced corrugated paperboard comprises a pair of outer liner sheets and a corrugated intermediate sheet or medium. Corrugated paperboard with two facing corrugated intermediate sheets is also used.

Sheets of corrugated paperboard are manufactured on large corrugator machines having a large number of interacting elements. All elements of the machine must be matched to obtain the maximum output of corrugated sheets. This is particularly the case in the processing and handling of corrugated webs for cutting, slitting, scoring and, most importantly in stacking and handling corrugated sheets which are cut to a desired size. One of the major problems is that in order to handle such cut corrugated sheets efficiently a very long area is required which is expensive to provide and maintain.

There are also various problems which arise even with the most efficient corrugator machines. One problem is that in many cases due to processing difficulties, the sheets are often warped. There is a need for a simple and cheap method of handling such warped boards.

In addition, there is a serious problem with dust generated in the cutting operations. Small particles of dust are retained on the sheets and these cause problems, particularly imperfections when printing on the sheets.

This invention is directed towards providing an improved process for producing sheets of corrugated paperboards which will overcome at least some of these difficulties.

According to the invention there is provided a process for producing sheets of corrugated paperboard comprising the steps of : delivering an intermediate web or medium from a mill roll; forming fluted corrugations transversely across the medium; applying liquid adhesive to the tips of the flutes on one side of the corrugated medium; leading a first liner web from a mill roll; contacting the adhesive-coated corrugated flutes with the first liner web in a single facer to form a single face web; preheati#ng the single face web in a preheater unit; applying liquid adhesive to the exposed tips of the flutes of the single face web in a gluing unit; leading a second liner from a mill roll; preheating the second liner in the preheating unit; contacting the second liner web with the adhesive-coated corrugated flutes to form a double face web; curing the adhesive by passing the double face web through a heating section while applying traction to the continuous web of corrugated paperboard thus formed; directing the web of corrugated paperboard upwardly to a rotary shearing station; delivering the sheared web upwardly to a scoring and slitting station to form longitudinal laterally spaced slits in the web; directing the corrugated paperboard web upwardly onto either an upper corrugated web track or a lower corrugated web track; cutting the corrugated web to length at a duplex cut-off station to form corrugated sheets of desired size; delivering the corrugated sheet upwardly from the cut-off station to a respective upper or lower stacking station; automatically downs tacking the cut sheets onto a stacking bed; automatically lowering the stacking bed as the stacking continues to form a stack of a desired number of corrugated sheet; delivering the stack of corrugated sheets to a conveyor; and conveying the stack of corrugated sheets to a desired location.

In one embodiment of the invention, the stack of corrugated sheets are conveyed to the desired location by a mobile trolley.

In one embodiment of the invention each of the webs are led from one of two mill roll stands and web from one mill roll is automatically spliced to web from the other mill roll for substantially continuous feed of web on demand.

In another embodiment of the invention, the process includes the step of inspecting the corrugated sheets and applying a correcting bending force to correct any warping of the corrugated sheets. Preferably the process comprises supporting a corrugated sheet having a warp to be corrected between a pair of spaced-apart backing means with the bow of the warped sheet uppermost and approximately centrally disposed with respect to the backing means and urging a bending means against the bow of the sheet to correct the warp. In one preferred arrangement, the backing means comprises a pair of spaced-apart backing rollers and the bending means comprise a bending roller located in the gap between and above the backing rollers.In a preferred embodiment of the invention, the process includes the step of adjusting the position of the bending roller in accordance with the degree of warp of the corrugated sheet to be corrected.

In one embodiment of the invention the process includes the step of removing dust generated in the cutting step.

Preferably, the dust is removed by ionising dust particles, vibrating the ionised particles and removing the ionised particles by vacuum.

The invention also provides sheets of corrugated paperboard whenever prepared by a process of the invention.

The invention will be more clearly understood from the following description thereof, given by way of example only with reference to the accompanying drawings, in which: Fig. 1 is a schematic side elevational view of a process of producing sheets of corrugated paperboard material according to the invention, Fig. 2 is a side view on an enlarged scale of part of the apparatus of Fig. 1, Fig. 3 is a side view on an enlarged scale of another part of the apparatus of Fig. 1, Fig. 4 is a plan view of the part of the apparatus illustrated in Fig. 3, Fig. 5 is a perspective view of part of the apparatus, Fig. 6 is a perspective view of an apparatus used in correcting warp in corrugated sheets in the process of the invention, Fig. 7 is a side view of the apparatus of Fig. 6, and Fig. 8 is a perspective view of a detail of the apparatus of Fig. 7.

Referring to the drawings, and initially to Figs. 1 to 5 thereof there is illustrated a process for producing sheets of corrugated paperboard according to the invention. The corrugated paperboard is used in the manufacture of boxes and is made up of paper sheets. The invention will be described with reference to the production of double face corrugated paperboard comprising a pair of outer liner sheets and a corrugated intermediate sheet or medium. It will be appreciated, however, that corrugated paperboard with two or more facing corrugated intermediate sheets may also be manufactured by the method of the invention. The corrugated board may have a B type flute with an average of 47 flutes per ft. or a C type flute with an average of 39 flutes per ft.

In the case of C flute type corrugated board, a first or inner liner web is led from one of two mill inner liner C type roll stands 1 to a preheater 2 and then to a C flute single facer 3. An intermediate web or medium is led from one of two mill C type fluting medium roll stands 4 through a preconditioner 5 and then to the single facer 3 where liquid adhesive applied to the tip of the flutes on one side of the corrugated medium is bonded to the inner liner web from the mill roll stands 1 to form a single face C type web 6. The single face web 6 is passed over an upper table 7 and then through a preheater 8 and a duplex glue unit 9.A second or outer liner web is led from one of two mill outer liner roll stands 15, through the preheater 8 and glue unit 9 and then to a double backer belt 16 which applies the outer liner web to the adhesive coated exposed tips of the flutes to form a single wall corrugated board. The single board is drawn over hot plates 20 by a traction unit 17 including drive units for upper and lower belts 18, 19 which grip the board therebetween and draw it over the hot plates 20 where the starch adhesive is cured and then cooled for final curing.

In the case of B flute type corrugated board, an inner liner web is led from one of two mill inner B type liner roll stands 25 through a preheater 26 to a B flute single facer 27. The B type intermediate web or medium is led from one of two mill B type fluting medium roll stands 28 through a preconditioner 29 and then to the B type single facer 27. In the B type single facer 27 liquid adhesive applied to the tip of the flutes on one side of the corrugated medium is bonded to the inner liner web to form a single face B type web 31. The single face B type web 31 is passed over a lower table 32 and then through the preheater 8 and glue unit 9. The second or outer liner for the B type web 31 is delivered from the outer liner mill roll stands 15.

Each pair of mill roll stands 1, 4, 25, 28 and 15 have respective splicer units la, 4a, 25a, 28a, 15a for quick changeover from one mill roll to another.

The C flute single facer 3 in this case is a fingerless vacuum system whereas the B flute single facer 27 is a fingerless air pressure system for higher throughput of B type corrugated board.

The web of corrugated paperboard, whether B or C flute type, is then directed upwardly to a rotary shearing station 35 having a diverter for feeding in-feed slider tables 37 which direct the web upwardly to a slitting and scoring station 40, at the outlet or which the web may be directed into one of two streams, both of which are led upwardly to a double level direct drive duplex cut-off knife 45 to form sheets of corrugated material cut to a desired length.

The sheets of corrugated material are then delivered along upper and lower conveyors 46, 47 respectively to respective upper and lower stacking stations 50, 51, which are illustrated in particular detail in Figs. 3, 4 and 5.

The rotary shearing station 35 is used to cut off the corrugated board at the end of an order run. Corrugated sheets from the slitter scorer 40 may be delivered to either of the upper or lower tables 46, 47 so that two order runs may be processed simultaneously.

Referring particularly to Figs. 3 to 5, each of the stacking stations 50, 51 comprises a stacking bed 60, 61 which is movable upwardly to receive sheets of cardboard material to be stacked and which is directed downwardly as the sheets are led onto the stacker. Thus the cut sheets are automatically downstacked and when a stack of desired size is reached, the stacking table automatically lowers to the level illustrated to the right in Fig. 3 and by interrupted lines in Fig. 5, for discharge onto respective roller conveyors 70, 71 which in turn discharge onto a mobile trolley 80 which runs on tracks 81 for delivering the stack of cardboard sheets to a desired storage location, or to a further processing station, for example, a printing station.

The handling of the web or corrugated material, by directing it upwardly towards slitting, scoring and cutting stations and then downs tacking the sheets which are automatically transferred onto roller conveyors and then onto a trolley, greatly improves the processing efficiency. By transferring the web and sheets upwardly between the various stations, the overall length of the corrugating machine is substantially reduced which not only saves space, but also significantly increases processing efficiency and significantly reduces handling.

Irregardless of how closely controlled and monitored the process for producing sheets of corrugated paperboard is, a substantial quantity of corrugated sheets produced by the process are bowed or warped, as illustrated in Fig. 6.

Referring particularly to Figs. 6 to 8, in the process of the invention the sheets are inspected and any corrugated sheets which are warped are treated by applying a bending force to correct any warp. In the invention a corrugated sheet 109 having a warp to be corrected is passed between a pair of spaced-apart backing rollers 110, 111 with the bow of the warped sheet uppermost. A bending roller 115 located in the gap between and above the backing rollers 110, 111 is then urged downwardly against the bow of the sheet 109 to correct the warp as the sheet is passed through the rollers.

As will be particularly apparent from Fig. 7, the bending roller 115 is rotatably mounted on crank arms 120 which are rotatably mounted at 121. An adjustment means comprising a screw bar 126, which is adjusted by a handle 127 moves the crank arm 120 supported the bending roller 115 to a desired position to apply a desired bending force to correct the warp in the corrugated sheet 109 as it passes over the rollers 110, 111. In this way, the warp in corrugated sheets is effectively, efficiently and cheaply corrected, thus saving a large amount of wastage.

Many variations on the specific embodiments of the invention described will be readily apparent and accordingly the invention is not limited to the embodiments hereinbefore described which may be varied in construction and detail.

Claims

1. A process for producing sheets of corrugated paperboard comprising the steps of: delivering an intermediate web or medium from a mill roll; forming fluted corrugations transversely across the medium; applying liquid adhesive to the tips of the flutes on one side of the corrugated medium; leading a first liner web from a mill roll; contacting the adhesive-coated corrugated flutes with the first liner web in a single facer to form a single face web; preheating the single face web in a preheater unit; applying liquid adhesive to the exposed tips of the flutes of the single face web in a gluing unit; leading a second liner from a mill roll; preheating the second liner in the preheating unit; contacting the second liner web with the adhesivecoated corrugated flutes to form a double face web; curing the adhesive by passing the double face web through a heating section while applying traction to the continuous web of corrugated paperboard thus formed; directing the web of corrugated paperboard upwardly to a rotary shearing station; delivering the sheared web upwardly to a scoring and slitting station to form longitudinal laterally spaced slits in the web; directing the corrugated paperboard web upwardly onto either an upper corrugated web track or a lower corrugated web track; cutting the corrugated web to length at a duplex cut-off station to form corrugated sheets of desired size; delivering the corrugated sheet upwardly from the cut-off station to a respective upper or lower stacking station; automatically downs tacking the cut sheets onto a stacking bed; automatically lowering the stacking bed as the stacking continues to form a stack of a desired number of corrugated sheets; delivering the stack of corrugated sheets to a conveyor; and conveying the stack of corrugated sheets to a desired location.

2. A process as claimed in claim 1, wherein the stack of corrugated sheets are conveyed to the desired location by a mobile trolley.

3. A process as claimed in claim 1 wherein each of the webs are led from one of two mill roll stands and web from one mill roll is automatically spliced to web from the other mill roll for substantially continuous feed of web on demand.

4. A process as claimed in claim 1, 2 or 3, wherein the process includes the step of inspecting the corrugated sheets and applying a correcting bending force to correct any warping of the corrugated sheets.

5. A process as claimed in claim 4, comprising supporting a corrugated sheet having a warp to be corrected between a pair of spaced-apart backing means with the bow of the warped sheet uppermost and approximately centrally disposed with respect to the backing means and urging a bending means against the bow of the sheet to correct the warp.

6. A process as claimed in claim 5, wherein the backing means comprises a pair of spaced-apart baking rollers and the bending means comprise a bending roller located in the gap between and above the backing rollers.

7. A process as claimed in claim 6, wherein the process includes the step of adjusting the position of the bending roller in accordance with the degree of warp of the corrugated sheet to be corrected.

8. A process as claimed in any preceding claim, wherein the process includes the step of removing dust generated in the cutting step.

9. A process as claimed in claim 8, wherein the dust is removed by ionising dust particles, vibrating the ionised particles and removing the ionised particles by vacuum.

10. A process substantially as hereinbefore described with reference to the accompanying drawings.

11. Sheets of corrugated paperboard whenever prepared by a process as claimed in any preceding claim.