EP1470070B1 - Document shredder with single-sheet feeding of stacked sheet material - Google Patents

Abstract

A method for destroying stacked sheets according to which the sheets are mechanically individualized, grasped and cut. To this end, the down-most individual sheet in the stack is grasped in its center section from below, is folded and removed from the stack as a part preceding the stack in the direction of conveyance and is then supplied to a cutting tool with the fold of its center section first.

Description

The invention relates to a document shredder, namely a device for im Substantial sheet by sheet destruct of stacked sheet Sheet material according to PCT WO 01/54820 A1.

In the known document shredder the sheet material is his cutting - possibly also for cross-cut - not in more or less isolated Leaf shape by hand but driven by a motor automatically from a stack of leaves fed. The known document shredder automatically pulls through preferably a continuously rotating friction wheel drive sheet by sheet from the bottom of the From the stack of leaves, folds the sheet in the middle and leads it with anticipatory crease the below the support for the stack of sheet stacker too.

The occasional sheet feeder to the cutting unit can also be used for a large Scaling a simple cutting unit of conventional document shredders use. Leave the trigger and the fold as well as the feed to the cutting unit in a simple design by a continuously rotating friction drive machine realize. The sheet by sheet destruction of the stack of sheets takes Although a certain time to complete, but after the sheet stacking feed completely automatically without manual assistance with structurally comparatively low Effort.

Essential part of the individual sheets from the bottom of the stack of sheet material and withdrawing transport means are two counter-clockwise at constant circulation speed driven carrier rollers. They grip with their as friction lining or perimeter equipped with grip teeth that in the sheet stack below Leaf on its overlying surface and push it from its two sides towards the leaf center. The middle of the sheet is thereby directed towards the passage deflected between the two drive rollers. The by this deflection resulting Blattzwickel or folding apex is between the two drive rollers through in the direction away from the stack down the underlying direction Cutting unit of conventional design by the exerted by the friction rollers Supplied thrust. There, the anticipatory Faltscheitel of the cutting discs of the cutting mechanism. The folded sheet is doubled Leaf sides lying on each other pulled by the cutting discs through the cutting unit.

To ensure that when gripping the lower sheet in the stack, ensure that the gusset formed during the merging of the blade halves in the middle of the sheet Folding vertex deflected downwards from the stack in the direction of the cutting unit is, the known document shredder contains a stack of sheets in the middle of above acting Andruckvorichtung. This is above the gap positioned above the two drive rollers and applied there the sheet material stack downward. It is their main task at the bottom of the Sheet stack peeled single sheet forming a downward direction Cutting mechanism towards and from the sheet material stack resulting gusset or folding apex force.

The present invention has for its object to provide a pressure device create, which when removing the stack lying in the bottom sheet generation a pointing in the direction of the cutting unit toward the leaf gusset or Faltscheitels even safer and more efficiently accomplished, the trigger device for Avoidance of injury to the outside shields and easy operation with good work safety.

This object is achieved by a construction according to claim 1. The solution allows it, the supplied Blattgutstapel during the Vemichtungsvorganges after to be covered externally by means of pivoting manually operated closure elements. The closure elements shield in the direction of each other in the manner of hinged lid halves the sheet stack to the loading side, so after above. Furthermore, they control both in their closed position and in their opening position. loading or loading as well as their manual transfer into their opening and in its closed position, the positioning of the printing elements. At her opening movement not only do the closing elements give unrestricted access free to the sheet stacking pad of the document shredder. Rather, remove them at their Opening movement and the printing elements from the access path to the sheet stacking pad. This allows the special gear technology linkage of the printing elements. They are automatically at the opening pivoting of the closure elements from the Auflageraum removed and are therefore not hindering the loading process.

When the closure elements are transferred into their closed position, the closure elements control the pressure elements as a function of the height of the to be destroyed Sheet stack in a suitable pressure position. In addition, they control after achieved Closed position the pressure of the printing elements on top of the sheet stack. This control is accomplished in a manner that is automatic without separate, from the outside attacking drive means each an optimal Andruckstellung and pressure-positioning of the printing elements ensures.

Advantageous structural design features of the subject invention are in include the dependent claims.

Fig. 1

einen Längsschnitt durch die erfindungsgemäße Vorrichtung zu Beginn eines Arbeitszyklus zur Vernichtung eines Blattstapels.

Fig. 2

in vergrößerter Form den linken Teil der Vorrichtung nach Fig. 1, deren rechten Teil man sich spiegelbildlich analog (s. Fig. 1) vorzustellen hat.

Fig. 3

eine Darstellung analog Fig. 2 mit bereits deutlich reduzierter Höhe des Blattstapels, d.h. nach bereits mehr als hälftiger Vernichtung der in Fig. 1 und Fig. 2 dargestellten Stapelhöhe.

Fig. 4

eine Darstellung analog Fig. 3 bei noch weiter bis auf wenige Blatt abgearbeiteter Stapelhöhe.

Fig. 5

eine Darstellung analog Fig. 2 bis 4 nach Abzug und Vernichtung auch des letzten Blattes des ursprünglichen Blattstapels (Fig. 1,2).

Fig. 6

eine Darstellung analog Fig. 2 bis 5, bei welcher das linke Verschlusselement - nachstehend der Einfachheit halber auch als "Verschlussdeckel" bezeichnet - um wenige Winkelgrade aus seiner in den Fig. 1 bis 5 dargestellten Schließstellung in Richtung auf seine Öffnungsstellung hochgeschwenkt ist und das Druckelement mit anhebt.

Fig. 7

eine Darstellung analog Fig. 6 nach Öffnung des Verschlussdeckels über bereits einen größeren Schwenkwinkel als in Fig. 6 und das Druckelement weiter anhebt.

Fig. 8

der Führungsvorsprung (50) setzt auf den Steuerarm (46), insbesondere auf die Steuerkurve (39) auf.

Fig. 9 bis 13

noch größere Öffnungsstellungen des Verschlussdeckels analog Fig. 6 bis zur maximalen Öffnungsstellung in Fig. 13, bei welcher die Auflage für einen neuen Blattgutstapel und der Zuführungsschacht für den Blattgutstapel vollständig unbesetzt sind.

Fig. 14

in vereinzelter Form die wesentlichen Gestell- und Bedienungsteile der erfindungsgemäßen Vorrichtung.

Fig. 15 und 16

in vereinzelter Darstellung die wesentlichen Getriebeglieder für die Halterung der beiden Druckelemente an ihren Lagersockeln und

Fig. 17

das den Schwenkantrieb übertragende Verbindungsglied zwischen einem Verschlusselement und dem Koppelgetriebe zur Schwenksteuerung eines Druckelements.

The invention will be explained in more detail with reference to an embodiment shown in the figures, which shows the subject invention and its essential functional parts in different functional positions. It shows:

Fig. 1

a longitudinal section through the device according to the invention at the beginning of a work cycle for the destruction of a sheet stack.

Fig. 2

in an enlarged form the left part of the device according to Fig. 1, the right part one has to imagine a mirror image analog (see Fig. 1).

Fig. 3

an illustration analogous to Fig. 2 with already significantly reduced height of the sheet stack, ie after already more than half annihilating the stack height shown in Fig. 1 and Fig. 2.

Fig. 4

a representation analogous to FIG. 3 at still processed to a few sheets processed stack height.

Fig. 5

a representation analogous to Fig. 2 to 4 after deduction and destruction of the last sheet of the original sheet stack (Figure 1.2).

Fig. 6

an illustration analogous to FIG. 2 to 5, in which the left closure element - hereinafter referred to as "closure lid" for simplicity - is pivoted by a few degrees from its closed position shown in FIGS. 1 to 5 in the direction of its open position and the pressure element with lifts.

Fig. 7

6 shows an illustration analogous to FIG. 6 after the closure cover has been opened, which already raises a larger pivot angle than in FIG. 6 and the pressure element.

Fig. 8

the guide projection (50) is based on the control arm (46), in particular on the control cam (39).

Fig. 9 to 13

Even larger opening positions of the closure lid analogous to FIG. 6 to the maximum open position in Fig. 13, in which the support for a new sheet stack and the feed slot for the sheet stack are completely unoccupied.

Fig. 14

in isolated form, the main frame and operating parts of the device according to the invention.

FIGS. 15 and 16

in isolated representation, the main gear members for the mounting of the two pressure elements on their bearing sockets and

Fig. 17

the pivotal drive transmitting connecting member between a closure element and the coupling mechanism for pivot control of a pressure element.

The document shredder 1 includes a support surface 4 with in a center in the support surface 4 positioned passage opening 5. This is used for the discharge of the two driver rollers 2,3 withdrawn from the bottom 6 of the sheet stack 7 Single sheets. The driver rollers 2,3 are partially within the passage opening 5 and stand with their upper outer circumference on the support surface 4 in the direction on the stack of leaves 7 addition. They are continuously in opposite directions in the directions of rotation 48.49 revolving driven.

Take with their friction-intensive or equipped by Mitnehmerelemente circumference the rollers 2,3 the stack 7 in each case the lowest sheet on its underside 6 and his seized leaf halves merge inside. This creates an in Feeding direction 8 to the cutting unit downwardly inclined folding apex. With this anticipatory Faltscheitel the doubled sheet is discharged in the feed direction 8, as which is described in detail in the generic state of the art. The driver rollers 2.3 so pull the lower sheet of the sheet stack 7 not only from the support surface. 4 but lead it as a conveyor in the manner described the located below the support surface 4, not shown cutting unit too.

The also in the area above the support surface 4 extending support space 9th for the sheet stack 7 is on both sides of the passage opening 5 of a respective bearing base 10 flanked for pivotal mounting in each case a closure element 11. One Closure element 11 is hereinafter also referred to as "closure lid" for the sake of simplicity. designated. The closure elements 11 are pivotable about the pivot axis 12 mounted on the respective bearing base 10. Close in its closed position (Fig. 1 to 5) the closure elements 11 the support space 9 upwards. At the destruction process the support room 9 is not accessible.

In the document shredder according to the invention, the two are the support space 9 flanking bearing pedestals 10 each have a closure element 11 to the respective Swivel axle 12 pivotally assigned. This puts the closure elements 11 with their cover effective as Abdeckauslegem 13 of their pivot bearing ends 14 in the direction of each other (Fig. 1). Their pivot axes 12 flank the Supporting space 9 for the sheet stack 7 on both sides. They run parallel to the not shown, perpendicular to the image plane of Fig. 1 extending slot direction of Passage opening 5 in the support surface. 4

The document shredder contains between its support surface 4 and the closure elements 11 positioned printing elements 15. These have the form of pressure plates on, which are perpendicular to the presentation of the drawing figures almost extend over the greater part of the width extension of the closure elements 11. The printing elements 15 act on the sheet stack 7 in the direction of the support surface 4. The respective bearing base 10 facing sides of the two Drukkelemente 15 are formed as socket-like joint carrier holder 16. Each articulated carrier holder 16 includes perpendicular to the drawing planes extending pivot axes 17,18 for the storage of a control link 19 and a Hublenkers 20 - both pivotable in the image plane.

The two pivot axes 17,18 of each articulated carrier holder 16 store only in the support space 9 protruding ends of the control link 19 and the Hublenkers 20. The respective socket-side (bearing base 10) ends of the control link 19 and of the stub shaft 20 (FIGS. 2 to 9) are pivot axes extending perpendicular to the image plane 21 and 22 pivotally mounted on the bearing base 10. While the housing fixed Bearing base 10 of the shredder is stationarily positioned form the control handlebars 19 and the Hublenker 20, the two members of the coupling of a rocker arm effective joint carrier holder 16 and its associated pressure element 15th Die Support of the pressure element 15 takes place on the joint carrier holder 16 so by a linkage or coupling gear in the manner of a rocker arm.

The connecting link 23 between a closure element 11 and its associated Hublenker 20 includes at its bearing base end a rotary push joint 24. The rotary push joint 24 facing away from the upper end of the connecting link 23 is pivotally connected to the closure member 11 about the pivot axis 25. The pivot axis 25 extends like all other pivot axes perpendicular to the drawing planes.

The pivotal connection between connecting link 23 and Hublenker 20 attacks an effective as a lever extension spur 26 of the Hublenkers 20 at. This Extension spur 26 is in the manner of a stubby lever arm on the sokkelseitige (Bearing base 10) hinge axis 22 of the Hublenkers 20 also forms with the Hublenker 20 a two-armed lever.

The rotary push joint 24 of the connecting link 23 with the hinge 45 as a rotary joint part acts on the free end of the extension spur 26 attacking as to the joint 45 effective lever on the handlebar 20. The thrust direction of the rotary joint 24 extends in the longitudinal direction of the connecting link 23rd

The bearing pedestal 10 are in side walls of a feed slot 27 to the support surface 4 integrated or firmly connected.

Each pressure element 15 extends with the hinge carrier holder 16 facing away from it, projecting into the support space 9 projecting end 29 to the passage opening 5 for the withdrawn Blattgut.

Between control link 19 and pressure element 15, a tension spring 28 is effective. The Tension spring 28 acts on the pressure element 15 in its edition on the sheet stack. 7 pioneering direction. She tries so to speak, the pressure element 15 with its free cantilever 29 to lift up. In conjunction with the four-bar linkage 10,19,16,20 results from the tension spring 28 for the total movement of the Drukkelementes 15 an additional pressure down on the paper stack. 7

The tension spring 28 is with its the control arm 19 facing the end approximately midway fixed to the hinge ends 17,21 of the control link 19 at this. The fixation takes place on a projecting in the direction of the closure element 11 Fixiervorsprung 30th

With a large stack thickness 31 (FIG. 1, 2) with a corresponding distance height from the support surface 4 is the pressure element 15 with its projecting end 29 to the passage opening 5 of the support surface 4 inclined towards (inclination angle 32). The size of the angle of inclination 32 reduces with shrinking stack thickness to an approximate parallel position at a middle stack thickness 33. At low, the stack height approximated zero or completely the stack height zero corresponding distance 34 is the pressure element 15 with its joint carrier holder 16 on the sheet stack 7. In this position is the respective pressure element 15 in the direction of the passage opening 5 rising inclined (inclination angle 35, Fig. 4), so that its projecting end 29 no pressure more in the direction of bearing surface 4 exercises. In this end position (Fig. 5) acted upon Meanwhile, the pressure element 15 facing him, as a scraping edge 36 for staple serving end edge of the support surface 4 optionally under clamped intermediate position of remaining sheet material of the processed pile.

The pressure element 15 facing the end of the control link 19 is about his there associated pivot axis 17 to form a in the direction of the contact surface 4 angled protruding dog stop 37 addition. The driver stop 37 strikes at above the frame-side pivot bearing 21 of the control handle 19 lying pressure element side pivot axis 18 of the Hublenkers 20 and partially pivoted (Fig. 9,10) closure element 11 with correspondingly upstanding Positioning of the pressure element side pivot bearing 17 of the control arm 19 for its pivotal movement on a pressure element side counter-stop 38 in the region of the joint carrier 16. The Mitnehmeranschlag 37 transmits with further opening pivoting 47 of the closure element 11 thereby generated Torque to further increase the pressure element 15 in from the support surface 4 opposite direction. (Figure 9). This is true up to the raised rotational position of the closure element 11 according to FIG. 10. The further pivoting of the Drukkelementes 11,12 to the extreme open position shown in FIG. 13 takes place on the control cam 39 of the control arm 46, which the control link 19, through the Guide projection 50 extended beyond its bearing base pivot axis 21 addition and to a two-armed lever effective on both sides of the pivot axis 21 designed.

The control link 19 is thus at its end facing away from the pressure element 15 with its control arm 46 via its pivot bearing 21 on the bearing base 10 addition. Of the Control arm 46 further includes at its end remote from the pivot axis 21 a Sales area 40 and an end stop surface 41 and the stand in a blunt Angle to each other. At over the summit of his pivoting path (Fig. 12) going out Aufschwenkstellung of the closure element 11 meets the at the outer end of the Closing element 11 arranged end stop 43 on the shoulder surface 41 of Control arm 46.

The impact of the operator in the further opening direction 44 applied to the closure member 11 and in the counterclockwise order the pivot axis 12 effective drive torque fully on the end stop 43rd transferred to the control arm 46 and than about the pivot axis 21 in the counterclockwise direction effective pivoting moment on the control link 19 effective. Thereby pushes the control link 19, the pressure element 15 in the counterclockwise direction over his vertical top dead center position (FIG. 12) also in an approximated parallel position for with respect to the support space 9 further outwardly pivoted closure element 11. This makes the support space 9 from above for the insertion of a sheet stack 7 freely accessible.

Below is a duty cycle of the document shredder in its individual steps starting from the insertion position for the sheet stack 7 (FIG. 13) the closure of the support space 9 by closing pivoting of the closure elements 11 (going back to Fig. 12 to Fig. 8 and then Fig. 1, 2) and via the subsequent one Processing of the sheet stack 7 to its destruction (Fig. 1 to 5) to the final Opening pivoting of the closure element 11 (or better both Closure elements 11) in the full open position (Fig. 13) in respective individual steps described.

The two closure elements 11 of the document shredder respectively act correspondingly together. That means the swinging motion one of the closure elements 11 synchronously an analogous Aufschwenkbewegung also the other closure element 11 by a synchronous drive, not shown here causes. A Zugmittelverbindung between two closure elements 11 provides for a respective same angular position of the closure elements 11 with respect to their Swivel axes 12, even if a pivoting only one of the two closure elements 11 is done by the operator. This is how the synchronous swinging turns causes.

The sheet stack 7 is located in extreme open position closure elements 11 and pressure elements 15 (FIG. 13) are inserted from above into the support space 9. Subsequently pivot the closure elements 11 from their upright opening position in the substantially horizontal closed position (Fig. 1). These Pivoting movement is synchronous by both closure elements 11, each with the same Swing angle completed. In this case, the two closure elements 11 associated pressure elements 15 taken in the manner described. The on the loading operation the following closure position is shown in Fig. 1. Act on it both pressure elements 15 with their in the direction of the region of the passage opening 5 downwardly inclined cantilever 29 the sheet stack 7 in its center.

Then, the trigger device in the form of the two permanently counter-rotating Mitnehmerrollen 2.3 turned on. Leaf by leaf is the leaf stack 7 of his Run down side 6 ago, as in the aforementioned WO 01/54820 A1 is described in detail.

In the course of processing the sheet stack 7, the rotational position of the two changes Pressure elements 15 relative to the sheet stack 7 in the in Figs. 2 to 5 shown Wise. There, only the left pressure element 15 is shown and this is increasing with Processing the sheet stack 7, i. with its decreasing to zero Stack height pivoted counterclockwise 31,33 with the result that at the stack height Zero (FIG. 5) the pressure element 15 emphasizes the wiping edge 36 of the support surface 4 charged. Apply at start of batching at maximum stack height the pressure elements 15 with their projecting ends 29, the sheet stack 7 centrally in the catchment area the driving rollers 2,3. This favors the friction of the driver rollers 2.3 with the surface facing the lower sheet layer of the sheet stack. 7 and ultimately brings about the desired center folding. In this initial state extends the weight in the region of the scraping edges 35 on the lower sheet layer of the remaining stack to ensure stripping about adhering staples.

In the meantime, however, this self-weighting is reduced during the course of the composition process increasing stack thickness 33. The associated reduction of the sheet stack weight resulting contact pressure on the wiper edge 36 is substituted with increasing approach of the residual stack height 33 to a zero height by an external pressurization of the wiper edge 36 from above the pressure element 15. This pressurization is intensified and to generate the desired wiping action supported by a counterclockwise successive pivoting of the pressure element 15 (FIGS. 2 to 5). This swing takes place together with the lowering of the pressure element 15 down in the direction on the support surface 4. The lowering of the pressure element 15 is by its own weight generated and shown in Figs. 2 to 5 pivoting of the pressure element 15 counterclockwise is a consequence of the four-bar mechanism. This results from a specifically different size of the pivot point / joint distances of the four-bar chain. The tension spring eliminates any play in the joints and tense the Four-link chain in the way, allowing an additional force of the pressure element after is generated below.

After complete processing or destruction of the sheet stack 7 (FIG. 5), the Cover arm 13 of the closure element 11 in the opening direction 47 (Fig. 5) swung open. Due to the synchronous connection of the mutual pivot bearings an analogous Aufschwenkbewegung on the right side with the local closure element 11. With this pivoting in the opening direction 47 of the connecting link 23 pulled up. The connecting link 23 pivots the extension spur 26 in the region of its end 45 counterclockwise to the Swivel axis 22 on the bearing base 10. This rotary actuator causes a high swing of the Hublenkers 10 in the counterclockwise direction about the pivot axis 22. Als As a result, the pressure element 15 is lifted from the support surface 4 upwards. The opening pivoting of the closure elements 11 in the opening direction 47 is up to the stroke position shown in Fig. 9 by the Hublenker 20 on the pressure element 15 transmitted.

From the achieved half-opening rotational position of the closure elements 11 (FIG. 9) starting running at the rear end of the closure element 11 positioned Guide projection 50 on the control cam 39 of the control arm 46 (FIG. 10). The 9 beyond, shown in FIGS. 10 to 13 end pivoting of the two Pressure elements 15 in their definitive, the access to the support surface 4 from above completely releasing, upwards teal unfolding opening position (FIG. 13) will continue to pivot apart in the opening direction 44 the closure elements 44 causes. The by the divergence of the Shutter elements 11 produced rotary drive is from the approximately in Figs. 9/10 shown Partial opening position of the closure elements 11 by the sliding of the latter with the rear pivot arm 51 of the closure element 11 connected Guide projection 50 on the control cam 39 as about the pivot axis 21 in the counterclockwise direction Effective torque from the control arm 46 to the control link 19th transfer. This raises the control arm 19 with his the support space 9 for the Sheet stack 7 facing end of the pressure element 15 via the pivot axis 17 in Opening direction 47 on. With the lifting of the pressure element end of the control link 19 whose pivoting about the pivot axis 21 is connected. This pivotal movement generated in the region of the joint carrier-side pivot axis 17 of the control link 19, a pivoting of the pressure element 15 in the counterclockwise direction. This pivots the projecting end 29 of the pressure element 15 in Counterclockwise in the opening direction 47 on. Starting from the closed position of the closure element 11 according to FIG. 5, the opening pivoting of the pressure element rushes 15 of the opening pivoting of the closure element 11 initially into a half-opening position of the closure element 11 (FIG. 9/10). Then he runs Guide projection 50 on the control cam 39 of the control arm 46. At further Opening pivoting of the closure element 11 now pivots the pressure element 15 at a higher rotational speed than the closure element 11. The pressure element 15, in a sense, takes you to the half-open position (Fig. 9/10) the closure element 11 lost angular position again, until the unfolded Extreme open position shown in FIG. 13 is reached, in which the pressure element 15 assumes an approximate parallel position to the closure element 11.

When closing the closure elements against the direction 47 moves the Guide projection 50 along the opposite curve of the cam 39 along and leaves leading the pressure element 15 during the closing movement.

This overall construction also allows a single sheet feeder through two individual lids to.

LIST OF REFERENCE NUMBERS

1

Shredders

2

tappet roller

3

tappet roller

4

bearing surface

5

Port

6

bottom

7

sheet stack

8th

feed

9

circulation space

10

bearing socket

11

closure element

12

swivel axis

13

Abdeckausleger

14

Pivot end

15

pressure element

16

joint carrier

17

swivel axis

18

swivel axis

19

control link

20

Hublenker

21

swivel axis

22

swivel axis

23

connecting link

24

Turning and sliding joint

25

swivel axis

26

extension spur

27

insertion slot

28

mainspring

29

cantilevered

30

fixation

31

stack height

32

tilt angle

33

Avg. stack thickness

34

distance

35

tilt angle

36

stripping

37

driver stop

38

counterstop

39

cam

40

Swivel stop surface

41

shoulder surface

42

inside edge

43

end stop

44

opening direction

45

joint

46

control arm

47

opening direction

48

direction of rotation

49

direction of rotation

50

guide projection

51

swivel arm

Claims (17)

1. Apparatus for destroying stacked sheet material essentially sheet by sheet using a cutting unit,

   having a support surface (4) for the sheet stack (7),

   having a slot-like through-opening (5) which is positioned approximately centrally in the support surface (4) and is intended for the removal of a sheet drawn off from the underside (6) of the stack (7), and

   having a conveying arrangement which

   draws off the sheet material from the support surface (4) and

   feeds it to the cutting unit located beneath the support surface (4),

   in the case of which sheet-destroying apparatus the support chamber (9) for the sheet stack (7) is flanked on both sides of the through-opening (5) by in each case one bearing base (10) for pivotably mounting in each case one closure element (11),
   which closure elements (11)

   cover the support chamber (9) from above during the sheet-destroying operation and, for this purpose,

   can each be pivoted, in the manner of cover halves, above pivot pins (12), which are in each case approximately parallel to the slot direction of the through-opening (5) and flank the support chamber (9) for the sheet stack (7) on both sides, from an open position (figures 12 and 13), in which the support chamber (9) is freed, into a closed position (figures 1 to 5), in which the support chamber (9) is essentially covered, and vice versa, it being the case that the apparatus bears pressure-exerting elements (15) which are positioned between its support surface (4) and the closure element (11) and are intended for pressing the sheet stack (7) against the support surface (4), and that each pressure-exerting element (15) is articulated on the bearing base (10), in the manner of the connecting rod of a crank-rocker linkage, by means of a displacement link (20) and of a control link (19) and is connected, via an articulation element which acts on the displacement link (20) and is acted as a connecting link (23), to the closure element (11), such that, by virtue of the closure element (11) being pivoted open or closed, the pressure-exerting element (15) is pivoted along into a pressure-exerting position or open position corresponding to the open position (Figures 12 and 13) of the closure element (11).
2. Apparatus according to Claim 1, characterized in that the connecting link (23), which is active between the displacement link (20) and the closure element (11), contains a rotary/pushing-action articulation (24).
3. Apparatus according to Claim 2, characterized in that the pivoting connection between the connecting link (23) and displacement link (20) acts on an extension spur (26) of the displacement link (20), this spur (26) being active as a lever, projecting in the manner of a stub-like lever arm beyond the base-side articulation (22) of the displacement link (20), and forming a two-armed lever with the displacement link (20).
4. Apparatus according to Claim 2 or 3, characterized in that the pushing-action direction (26) of the rotary/pushing-action articulation (24) runs in the longitudinal direction of the connecting link (23).
5. Apparatus according to one of the preceding claims, characterized in that the bearing bases (10) are integrated in side walls of a feed shaft (27) to the support surface (4).
6. Apparatus according to one of the preceding claims, characterized in that the displacement link (20) and the control link (19), as far as the pressure-exerting element is concerned, are articulated on that side of the respective pressure-exerting element (15) which is directed toward the bearing base (10).
7. Apparatus according to Claim 6, characterized by articulation (pivot pins 17, 18) on a respective articulation carrier (16) which, directed toward the associated bearing base (10), is connected to the respective pressure-exerting element (15).
8. Apparatus according to one of the preceding claims, characterized in that a pressure-exerting element (15), by way of its projecting end (29), which is directed away from its articulation carrier (16), projects as far as the through-opening (5) for the drawn-off sheet material.
9. Apparatus according to Claim 8, having a pair of friction rollers (2, 3) as the drawing-off arrangement, this pair of rollers acting on the sheet stack (7) from its underside (6) and circulating in opposite directions (8, 9) about the axes which are approximately parallel to the slot-like longitudinal direction of the through-opening (5), characterized by a projecting length (Figures 4 and 5) which extends as far as the region of action of the respectively associated friction roller (2, 3).
10. Apparatus according to one of Claims 1 to 9, characterized by a tension-spring connection (28) which acts between the control link (19) and pressure-exerting element (15) and forces the pressure-exerting element (15) upward in the opening direction (47), which is oriented away from the support surface (4).
11. Apparatus according to Claim 10, characterized in that the fixing point (30) for the tension spring (28) on the control link is positioned between the articulation ends (17, 21) of the control link (19).
12. Apparatus according to one of the preceding claims, characterized in that, in the case of a large vertical spacing from the support surface (4) or in the case of a large stack thickness (31) (Figures 1 and 2), each pressure-exerting element (15) has its projecting end (29) inclined in the direction of the through-opening (5) of the support surface (4).
13. Apparatus according to Claim 12, characterized by a reduction in the magnitude of the angle of inclination (32) in the case of a reduced vertical spacing or reduced stack thickness (33) (Figures 3 and 4).
14. Apparatus according to Claim 12 or 13, characterized in that, in the case of a small spacing from the support surface (4) close to or equal to a stack thickness of zero, the pressure-exerting element (15) is inclined in a state in which it slopes up from the support surface (4) in the direction of the through-opening (5), such that its projecting end (29) exerts pressure not on the sheet stack (7), but on the side edge which is directed toward the bearing space (10) (= stripping edge 36 of the support surface 4) (Figure 5).
15. Apparatus according to Claim 14, characterized in that the pressure-exerting element (15) acts on the facing staple-stripping edge (36) of the support surface (4), with the interposition of the rest of the sheet material of the processed sheet stack (7).
16. Apparatus according to one of the preceding claims, characterized in that that end of the control link (19) which is directed toward the pressure-exerting element (16), projecting beyond the pivot pin (17) of the control link positioned there, is angled in order to form a carry-along stop (37), which projects in the direction of the abutment surface (4) and, in the case of the pressure-exerting-element-side pivot bearing (17) of the control link (19) being positioned above the support-side pivot bearing (18) of the displacement link (20) and in the case of the closure element (11) being pivoted open in part, strikes against a mating stop (38) of the pressure-exerting element (15) and, with continued abutment, raises the pressure-exerting element (15) in the direction away from the support surface (4) (Figures 9 and 10).
17. Apparatus according to one of the preceding claims, characterized in that, at its end which is directed away from the pressure-exerting element (15), the control link (19) projects beyond its pivot bearing (21) on the bearing base (10) by way of a control curve (39), which

    forms a two-armed lever with the control link (19) and

    in the case of the closure element (11) finally pivoting into its definitive open position (figures 12 and 13), transmits the rotary drive power from the manually pivoted closure element (11) to the associated pressure-exerting element (15) and pivots the pressure-exerting element (15) into the definitive raised position (Figure 13).

Images