EP0150655B1

EP0150655B1 - Apparatus for slowing cut size sheets

Info

Publication number: EP0150655B1
Application number: EP84630174A
Authority: EP
Inventors: Kenneth G. Frye; Donald R. Grody; Donald Ch. Fitzpatrick
Original assignee: Beloit Corp
Current assignee: Beloit Corp
Priority date: 1983-12-02
Filing date: 1984-11-16
Publication date: 1988-05-11
Also published as: NO158296C; FI844251L; DE150655T1; JPS60137763A; MX161877A; CA1221712A; ES537986A0; PH22269A; EP0150655A1; BR8405924A; KR860001631B1; KR850004504A; DE3471081D1; ATE34152T1; ES8603337A1; NO844699L; NO158296B; FI844251A0; SU1449008A3

Abstract

A means for slowing cut sheets in seriatum flow by nipping the trailing edge of the sheets as they leave a high-speed conveyor system is provided whereby the sheets pass to a stacking pile at a slow speed. The nipping means is disclosed in several embodiments including a brush carrying roll (24) an oscillating roll on a lever arm and an air jet means. Ream removal means (40) are also provided to remove reams (38) of paper from the bottom of the stacking pile (36).

Description

The invention relates to an apparatus and a method for slowing cut size sheets as defined in the pre-characterizing portion of claims 1 and 19 respectively.
Such an apparatus and such a method are known from DE_-B-1 561 728 which discloses a sheet conveying apparatus including a slowdown assembly which is positioned between the delivery end of a belt conveyor and a collection zone. The slowdown assembly comprises a lower slowdown roll and an upper oscillating roll forforming a hard nip with the slowdown roll to slow the sheet. The. oscillating roll is driven so that the sheet passing between the two rolls is nipped only at its tail end. While the known apparatus allows multiple sheets to pass therethrough, the sheets are not overlapped at the point of slowdown. Overlapped pairs are advanced but each represents a discrete pile of two sheets which are cut from multiple webs in the sheeter. Thus the discrete piles of sheets are already in overlapping formation as they approach the slowdown zone. The sheets are advanced continuously through the slowdown zone, and once they have been slowed they advance at the speed of the slowdown roll. The use of a hard nip as slowdown means is disadvantageous because hard nips tend to mark the sheets and do not compensate for caliper changes across the sheet.
DE-A-2 841 658 discloses also an apparatus and a method for slowing cut size sheets. Although the apparatus allows overlapping of successive sheets during slowdown, it relies on vacuum for slowing the sheets. To this end a reciprocating suction bar is provided which holds the sheet so that it moves forwardly at the speed of the suction bar. A rotary brush cooperates with the suction bar in that it deflects the tail end of the sheet downwardly into the sphere of action of the suction bar so as to enable the suction bar to grab the tail end and advance the grabbed sheet toward the collection zone. Thus, the brush is only a tail knock down device, not a slowdown device. Several problems arise when vacuum alone is the technique used for slowing sheets. Vacuum does not work well with multiple webs, and vacuum does not work well at higher speed because of the much greater inertia of the sheets. With multiple webs vacuum acts more effectively on the bottom sheets that on the top sheets, and the inertia of the top sheets tend to carry through. Thus, a phenomenon known as "shuffling" results wherein the top sheet advances farther than the lower sheet. This becomes critical at higher speeds.
An object of the invention is to improve the apparatus and the method of the kind defined in the pre-characterizing portion of claims 1 and 19 respectively so that cut sheets, which are conveyed at a high speed, are slowed down effectively and caused to overlap as they are fed to the collection zone without there being a risk for the sheets to be damaged.
This object of the invention is achieved by incorporating the features stated in the characterizing portion of claims 1 and 19 into the apparatus and the method defined in the pre-characterizing portion of these claims respectively.
An advantage of the apparatus and the method according to the invention resides in that a soft nip is formed between the rotating brush and the rotating slowdown roll, with the nip being responsible for slowing the sheets without causing any damage to them. Furthermore, the brush means is employed to not only form a soft nip with the roll to slow the sheets but also to knock down the tail of each sheet simultaneously, thus allowing the sheets to overlap as they are fed to the collection zone. A further advantage consists in that the sheets do not advance forward when they are not nipped against the rotating roll by the nip means. Each sheet merely sits on top of the rotating roll. It is only when the next successive sheet advances over the first sheet and a nip is formed with the nip means that the bottom sheet advances into the collection zone and the then top sheet advances to the position of the former bottom sheet. Thus, each pair of overlapped sheets are advanced into definite positions only during engagement of the nip means with the slowdown roll means. This ensures a better control of the stacking operation.
An embodiment of the invention will now be described by way of example and with reference to the accompanying drawings, in which

Fig. 1 is a schematic side elevational view of an apparatus according to the invention, and
Fig. 2 a schematic side elevational view of a modification of the apparatus shown in Fig. 1.

With reference to Fig. 1, there is illustrated a series of sheets, such as paper sheets 10, 12, 14 and 16 which have been cut by a knife into individual sheets upstream of Fig. 1 and are being passed in a seriatim flow. A high-speed tape conveyor system 18 having a tape means 20 supported at one end by a roll 22 and at the other end by a similar roll not shown, serves to convey the cut sheets at high speed. The high-speed tape 20 conveys the sheets at speeds of up to 457.5 m/ min.
Immediately downstream of the turnaround roll 22, there is provided a slowdown device in accordance with the principles of the present invention. In the embodiment shown in Fig. 1, there is provided a tail-stopping device which comprises a top brush roll 24 and a slowly rotating roll 26. Both rolls 24 and 26 are operated by means of an electric motor 28 operating through appropriate gearing means 30.
The slow rotating roll 26 rotates with a surface speed of approximately 76.2-106.7 m/min. The brush roll has two radially extending brush members 32, 34 which are diametrically opposed on the roll 24. As sheets are fed by the conveyor system 18, the lead edge of the sheets passes between the two rolls 24, 26 when the bush members 32, 34 are disposed approximately horizontally such that the lead edge can pass between the two rolls. As the sheet continues to pass between the two rolls, one of the brush members comes in contact with a portion of the sheet near the tail end and forces the sheet downwardly against the slowly rotating roll 26. As the brush member, which continues to rotate, leaves the roll 26, there is nothing to drive the sheet into the stacking pile, so it sits there until the brush comes around again, knocking the tail down of the next sheet. As that occurs, the brush member puts pressure on both sheets. In Fig. 1 it is seen that the brush member 32 is knocking down the tail end of sheet 10 while sheet 12 is still engaged with the slowdown roll 26. With the brush member putting pressure on both sheets, the bottom sheet 12 is accelerated to a speed of approximately 45.7-76.2 m/min. into the stacking pile as is shown by sheet 14. The top sheet 10 continues to sit on the unnipped-slow-speed roll 26, waiting for the next nip of the brush member. In this manner, delivery into the stacking pile at slow speed is accomplished.
More than one ream of paper sheets is collected in the stacking pile 36, which accomplishes the compaction needed to compress all of the air out of the pile. The reams are removed from the bottom of the pipe as seen in Fig. 1 where a ream 38 is being removed. A ream splitter spear 40 having a sharp pointed leading edge 42 for original entry into the stacking pile 36 and having a belt 44 on the spear is inserted into the stacking pile 36. The pointed leading edge separates a top sheet 46 of the ream 38 from a bottom sheet 48 of the stacking pile 36. The belt 44 on the spear 40 is supported at one end by a front roller 50 and at a second end by a rear roller 52. As the spear is inserted into the stacking pile 36 separating the ream 38 from the rest of the pile, the belt 44 moves on the rolls 50, 52 in a clockwise direction as viewed in Fig. 1 such that any portion of the belt 44 coming into contact with the bottom sheet 48 of the stacking pile 36 remains stationary with respect thereto until the spear is completely inserted into the stacking pile.
Depending downwardly from the spear 40 is a pusher plate 54 which engages a side-face 56 of the ream 38 and serves to move it laterally as the spear 40 is inserting into the stacking pile 36. The pusher plate 54 has a height at least slightly higher than the thickness of the ream 38 being separated in order to provide clearance as seen at 58 between the top sheet 46 of the removed ream 38 and the belt 44 which is moving around rollers 50 and 52.
The stacking pile 36 is normally supported by a lift table comprising two free wheeling conveyors 60, 62 which engage a bottom sheet 64 of the bottom ream in the stacking pile 36. The two conveyors 60, 62 comprise a split lift table which allows the reams to be supported while the spear 40 is being inserted and withdrawn. The two conveyors 60, 62 are mounted for independent vertical movement such that the ream and stacking pile 36 are continuously supported as required.
As the spear is inserted into the stacking pile 36 the pusher plate 54 moves the ream 38 which is supported on the free- wheeling conveyors 60, 62 toward an air table 66. When the ream 38 is deposited on the air table 66 as is shown in phantom, most of the weight of the paper is supported by an air cushion from air supplied under pressure through conduits 68 in the air table which are exposed to a top surface 70 of the table thorugh individual air ports 72. Longitudinal conveyor belts 74, 76 which extend above the surface 70 of the air table 66 are used to move the individual reams to the next station in the paper processing system.
As the spear is retracted from the stacking pile 36, the smaller free-wheeling conveyor 60 moves vertically to support the bottom of the stacking pile while the spear continues to be withdrawn. As soon as the spear is withdrawn, the second conveyor 62 moves vertically to also support the stacking pile.
It is desired that the top sheet, represented by sheet 16 in Fig. 1, of the stacking pile remain at the same level relative to the rolls 26, 24 throughout the entire stacking operation. Therefore, the spear 40, as well as th free-wheeling rollers 60, 62 is mounted for vertical movement on a shaft 78. Also, as seen in Fig. 1, a housing 80 for the stacking pile 36 has a portion cut away at 82 corresponding to the entry point of the spear 40 such that the spear is able to engage the stacking pile 36 while the pile is still held within the housing 80 and as the spear moves into the stacking pile 36 it will also move downwardly due to the additional sheets being stacked on the pile such that when it reaches an opposite wall 84 of the housing 80 it will pass beneath a lower edge 86 of that wall.
In Fig. 2 there is shown an alternative embodiment of the ream separating arrangement in which the stacking pile 36a, the spear mechanism 40a, the free-wheeling conveyor 60a and 62a and the air table 66a are all inclined to the same degree which allows for an enhancement of the stacking and separating procedure. The air table 66a has a side conveyor belt 88 associated therewith driven by motor 90 which moves the separated reams 38a to the next processing station as opposed to the bottom conveyor belt 74 and 76 of the embodiment shown in Fig. 1. In all other respects, the operation of this embodiment is the same as that shown in Fig. 1, this embodiment merely utilizes the force of gravity in assisting in the alignment of the stacking pile 36a and in the removal of the separated reams 38a.
Fig. 2 does shown the brush roller 24 in a different rotational position than that shown in Fig. 1 and it is seen that a sheet of paper 92 is being passed between the rollers 24, 26 by means of the high-speed tape mechanism 18. It is also seen that brush member 34 will contact the tail end of sheet 92 causing it to drop down against roll 26 where the pressure of the brush member 34 will cause the sheet 10 lying on the roll 26 to accelerate and move into the stacking pile 36a.

Claims

1. An apparatus for slowing cut size sheets (10, 12, 14, 16) is seriatim flow comprising: a high-speed conveyor system (18) which has a delivery end and a sheet carrying surface, a collection zone, and a slowdown assembly positioned downstream of said conveyor system delivery end and upstream of said collection zone, said slowdown assembly comprising lower slowdown roll means (26) driven by a motor means (28) to rotate at a slower speed than said conveyor system and having a sheet receiving surface disposed at a level below said sheet carrying surface of the conveyor system (18), and an upper intermittent nip means (24) for forming a periodic nip with said slowdown roll means (26) through which sheets pass to said collection zone, said nip means (24) being operable to selectively press each sheet into driving engagement with said slowdown roll means (26) for slowing so that the trailing edge of each sheet is nipped and the leading edge of each sheet passes unhindered between said slowdown roll means-(26) and said nip means (24), characterized in that said nip means comprises a rotating brush roll (24) spaced from said slowdown roll means (26) and has at least one brush means (32, 34) extending radially therefrom of a length sufficient to reach said slowdown roll means (26), said brush means (32, 34) being operable to knock said trailing edge of each sheet down against said slowdown roll means (26), allowing the next sheet to pass thereover and overlap, and cooperating with said slowdown roll means (26) to put pressure on both sheets so as to advance the bottom sheet into the collection zone and the top sheet to the previous position occupied by the bottom sheet, each sheet being advanced only while it is nipped by said slowdown roll means (26) and said brush roll (24).

2. The apparatus of claim 1 wherein said sheet carrying surface of said high-speed conveyor system (18) travels in the range of 122 to 457.5 m/ min.

3. The apparatus of claim 1 or 2 wherein said slowdown roll means (26) rotates at a surface speed in the range of 76.2 to 106.7 m/min.

4. The apparatus of anyone of the preceding claims wherein said brush roll (24) and said slowdown roll means (26) rotate in opposite directions.

5. The apparatus of anyone of the preceding claims wherein said slowdown roll means includes a rotating roll (26) which is driven to rotate continuously and is unnipped at least most of the time.

6. The apparatus of anyone of the preceding claims wherein said collection zone comprises a substantially vertical stacking pile (36; 36a) defined between an upstream wall (84; 84a) and a downstream wall (80; 80a).

7. The apparatus of claim 6 wherein said walls (80, 84) are disposed substantially vertical.

8. The apparatus of claim 6 wherein said walls (80a, 84a) are disposed at an angle to vertical wherein the bottoms of said walls (80a, 84a) are farther downstream than the top of said walls (80a, 84a).

9. The apparatus of anyone of claims 6 to 8 including a ream removing means (40, 54, 60, 62, 74, 76; 40a, 60a, 62a; 88) for continually removing reams (38, 38a) of said sheets from the bottom of said stacking pile (36; 36a).

10. The apparatus of claim 9 wherein said ream removing means comprises a spear means (40; 40a) for separating reams (38; 38a) from said stacking pile (36; 36a), a pusher means (54) associated with said spear means (40; 40a) for pushing said separated ream (38; 38a) away from said stacking pile (36; 36a), movable support means (60, 62; 60a, 62a) for supporting the bottom of said stacking pile (36; 36a), and conveyor means (74, 76; 88) for moving said removed ream (38; 38a) to a distant point.

11. The apparatus of claim 10 wherein said spear means includes a free rotating belt means (44) for engagement with a bottom sheet (48) on said stacking pile (36) above said removed ream (38; 38a).

12. The apparatus of claim 10 or claim 11 wherein said pusher means comprises a plate (54) depending downwardly from said spear means (40; 40a).

13. The apparatus of anyone of claims 10 to 12 wherein said movable support means comprises a plurality of free rolling conveyors (60, 62; 60a, 62a) independently movable toward said stacking pile (36; 36a) for support thereof and away from said stacking pile (36; 36a) during removal of said reams (38; 38a) and for clearance with said pusher means (54).

14. The apparatus of anyone of claims 10 to 13 wherein said conveyor means comprises a table member (66; 66a) for supporting said removed ream (38; 38a) and moving belt means (74,76; 88) for engaging said ream (38; 38a) and moving it to said distant point.

15. The apparatus of claim 14 wherein said table member comprises an air table (66; 66a) having air jets (72) supporting a portion of the weight of said ream (38; 38a).

16. The apparatus of claim 14 or claim 15 wherein said table member (66) has a substantially horizontal surface and said moving belt means (74, 76) is substantially parallel with said surface.

17. The apparatus of claim 14 or claim 15 wherein said table member (66a) has a surface disposed at an angle to horizontal and said moving belt means (88) is substantially perpendicular to said surface.

18. The apparatus of anyone of claims 10 to 16 wherein said spear means (40), said pusher means (54) and said movable support means (60, 62) are each vertically movable such that a top sheet (38) on said stacking pile (36) is kept substantially at the same level throughout the stacking operation.

19. A method for slowing cut size sheets (10, 12, 14, 16) passing in seriatim flow from a relatively high-speed conveyor system (18) having a carrying surface to a collection zone, comprising: dropping sheets of a delivery end of said high-speed conveyor system (18) such that the leading edge of each sheet extends horizontally outward, delaying each sheet downstream of the delivery end by passing each sheet through a slowdown nip forced by upper nip means (24) and lower slowdown roll means (26) such that the trailing edge of each sheet is nipped and the leading edge of each sheet passes unhindered, directing each sheet through said slowdown nip at a speed not greater than said slowdown roll means (26) such that each sheet passes individually to said collection zone at a slow speed, driving said slowdown roll means (26) in continuous rotation, and selectively intermittently causing said upper nip means (24) to nip each sheet in driving engagement with said lower slowdown roll means (26) characterized in further comprising: forcing the trailing edge of each sheet downwardly toward said lower slowdown roll means (26) as the sheet passes over said lower slowdown roll means (26); passing the leading edge of an immediately following sheet over the trailing edge of the sheet after the trailing edge has been forced downwardly; causing the lowermost of the then overlapped sheets to rest stationarily on said lower slowdown roll means (26) as the leading edge of the immediately following sheet passes thereover; forcing the immediately following sheet downwardly against the sheet resting stationarily on said lower, slowdown roll means (26); simultaneously causing said lowermost sheet to be advanced from its resting position into the collection zone and said immediately following sheet into the position previously occupied by said first mentioned sheet; each sheet being advanced only while it is nipped by said upper nip means (24) and said lower slowdown roll means (26).

20. The method of claim 19, further comprising: controlling the nipping of said upper nip means (24) so as to grasp each sheet in its trailing third portion.