CN220264502U

CN220264502U - Device for separating uppermost material sheets

Info

Publication number: CN220264502U
Application number: CN202320639297.0U
Authority: CN
Inventors: 斯蒂芬·格拉雷明; 齐格弗里德·艾萨克; 欧根·卡尔彭科夫; 安德烈·勒尔
Original assignee: Kolbus GmbH and Co KG
Current assignee: Kolbus GmbH and Co KG
Priority date: 2022-03-31
Filing date: 2023-03-28
Publication date: 2023-12-29
Anticipated expiration: 2033-03-28
Also published as: DE102022107710A1

Abstract

An apparatus for separating uppermost material sheets from a stack of sheets, comprising one or more separating devices of the same type provided with suction means and one or more separating devices of the same type provided with elastic restraining elements and blow nozzles, wherein the restraining elements and the blow nozzles are each arranged in a common frame of the separating devices.

Description

Device for separating uppermost material sheets

Technical Field

The utility model relates to a device for separating uppermost material sheets from a stack of sheets according to the preamble of embodiment 1.

Background

In order to separate the uppermost material sheet from the stack, it is known in particular to provide devices in the field of printing downstream processes, which grasp the sheet to be separated from above in the region of its front edge or in the region of its rear edge in a suction manner. In a vertical movement or in a curve with vertical portions, the region is lifted.

In this case, the separation does not necessarily take place between the uppermost sheet and the next sheet, depending on the material properties of the stack and the environmental conditions, such as the air humidity, etc. Instead, the sheets are lifted unintentionally and separated as partial stacks of the respective material groups.

For improvement, a blow nozzle is used which is directed laterally to the upper region of the stack. The blow nozzle is adjusted with respect to the material to be treated and other marginal conditions, respectively. This is mostly done according to trial and error principles, so that, in particular during the initial trial phase, errors in the separation and corresponding subsequent adjustment of the nozzle are tolerated.

In order to increase the process reliability, devices are known which slightly tilt the sheet to be separated at the gripping edge and thus elastically deform it as desired. The stresses that occur between adjacent sheets thus make the separation more reliable. First, the material properties, such as resistance to bending or to adhesion of the superimposed sheets, determine the necessary moving parts and the necessary suction force for tilting and lifting.

In order to achieve a simple construction and, above all, without excessively limiting accessibility, the displacement parts cannot be adjusted independently of one another due to the displacement curves which cannot be flexibly preset. On the other hand, the suction force cannot be arbitrarily increased without causing damage to the grasped sheet. It may also happen that the uppermost sheet is penetrated undesirably to other sheets.

Some sheets cannot bend to the extent necessary for reliable separation without damage occurring. Thus, the oblique movement curves for these materials are essentially excluded.

In addition, the separating system reaches its limit when the stack deviates excessively from the ideal state in the region of the sheet that is gripped when the separation is performed. In practice, however, firstly, poor flatness of the stacks and angle errors often occur during cutting.

Disclosure of Invention

The object of the present utility model is therefore to provide an improved device compared to the prior art, which overcomes at least one of the disadvantages of the prior art shown and which meets the higher demands on the process reliability that has to be achieved.

The present utility model provides an apparatus having the features described in embodiment 1 to solve the task. Advantageous variants of the utility model are described by the features in the dependent embodiments.

The foregoing description of the solution according to the utility model thus includes, inter alia, the various feature combinations defined by the subsequently numbered embodiments:

1. device for separating an uppermost material sheet (71) from a stack (7) of substantially flexible material sheets (71, 72), comprising at least

A frame (3) having at least two substantially vertically arranged carriers (33) defining an interior space (34), wherein the interior space (34) is used for receiving a stack (7) of material sheets (71, 72),

a transport device having at least one transport element for transporting the separated material sheets, and having a substantially horizontal withdrawal direction (300) in which the separated material sheets are guided away from the stack (7),

a separating device (1) having at least one suction element (11) arranged substantially above the stack (7), and having a first feed device (12) operatively connected to the at least one suction element (11) and having a substantially vertical feed direction of the at least one suction element (11),

a sheet separating device (2) having at least a blow nozzle (26) directed at the stack (7) of material sheets (71, 72) and an elastic restraining element (28) directed substantially at a substantially vertical face (74) of the stack (7) of material sheets (71, 72),

a second feeding device (51) operatively connected at least at times to the at least one sheet separating device (2), having a feeding direction substantially parallel to the withdrawal direction (300) of the separated material sheets, wherein the second feeding device (51) is adapted to define the position of the at least one sheet separating device (2) in the withdrawal direction (300),

wherein at least one separating device (1) and at least one sheet separating device (2) are arranged on the trailing edge of the material stack (7) in the withdrawal direction (300), and at least one blow nozzle (26) and an elastic limiting element (28) are directed substantially towards the trailing edge of at least one uppermost material sheet (71),

wherein the at least one sheet separating device (2) has at least one frame (21), wherein the at least one blow nozzle (26) and the at least one elastic restraint element (28) are arranged on a common frame (21).

2. The apparatus according to embodiment 1, wherein at least one third feeding device (22, 23) is provided in the frame (21) of the at least one sheet separating device (2), said third feeding device having at least one linear guide (221, 231), wherein the linear guide (221, 231) defines a feeding direction, and wherein the at least one third feeding device (22, 23) is operatively connected with the at least one blow nozzle (26) and/or the at least one elastic restraining element (28) such that the third feeding device (22, 23) determines the position of the at least one blow nozzle (26) and/or the at least one elastic restraining element (28) along the at least one linear guide (221, 231).

3. Apparatus according to any of the preceding embodiments, wherein at least one fourth feeding device (24, 25) is provided in the frame (21) of the at least one sheet separating device (2), said fourth feeding device having at least one rotational support, wherein the rotational support defines a pivot axis (101, 102), and wherein the at least one fourth feeding device (24, 25) is operatively connected with the at least one blow nozzle (26) and/or the at least one elastic restraining element (28) such that the fourth feeding device (22, 23) determines a rotational position of the at least one blow nozzle (26) and/or the at least one elastic restraining element (28) about the at least one pivot axis (101, 102).

4. The apparatus according to any of the foregoing embodiments, wherein the at least one frame (21) has an at least two-piece construction, wherein a first partial frame (211) is connected to the machine frame and the at least one blow nozzle (26) and/or the at least one elastic restraining element (28) are arranged in at least one second partial frame (212), and wherein the at least one second partial frame (212) is connected to the at least one first partial frame (211) by means of the at least one third feed device (22, 23) and/or by means of at least one fourth feed device (24, 25) such that the at least one third feed device (22, 23) defines a relative position of the at least one second partial frame (212) with respect to the at least one first partial frame (211) and/or the at least one fourth feed device (24, 25) defines a relative orientation of the at least one second partial frame (212) with respect to the at least one first partial frame (211).

5. The device according to embodiments 2 to 4, wherein the actuation force with respect to the at least one feed direction and/or the actuation moment with respect to the at least one pivot axis (101, 102) is greater than the inertial force generated by operation acting in the same at least one feed direction and/or the inertial moment acting around the same at least one pivot axis (101, 102).

6. The device according to any of the embodiments 3-5, wherein the at least one third feeding device (22, 23) and/or the at least one fourth feeding device (24, 25) has at least one spring (204), wherein the at least one spring (204) has a prestressing force and the prestressing force determines the starting force and/or starting moment of the at least one feeding device (22, 23, 24, 25).

7. Apparatus according to any of the preceding embodiments, wherein at least one blow nozzle (26) of the at least one sheet separating device (2) is configured as a fan nozzle having a central blow-out direction, and the blow nozzle (26) is pivotally accommodated in a frame (21) of the at least one sheet separating device (2) about a rotational axis (103), wherein the rotational axis (103) is substantially parallel to the central blow-out direction of the blow nozzle (26).

8. Apparatus according to any of the preceding embodiments, wherein the at least one sheet separating device (2) has at least one second elastic restraining element (27) which is at least at times arranged substantially above the uppermost sheet of material (71) and is directed towards a horizontal face (75) of the upper part of the stack (7), and at least one region of the second elastic restraining element (27) upwardly bounds the stack (7).

9. The device according to any of the preceding embodiments, wherein at least one lifting device arranged below the stack (7) has at least one vertically movable lifting element (58), wherein the at least one lifting element (58) limits the space of the frame (3) accommodating the stack (7) of material sheets (71, 72) downwards and the stack (7) of material sheets (71, 72) is placed on the at least one lifting element (58).

10. Apparatus according to any of the preceding embodiments, wherein the frame (3) has at least one linear guide (56) extending substantially transversely to the withdrawal direction (300), wherein at least two sheet separating devices (2) of the same type are individually positionable along the linear guide (56).

Drawings

The utility model is described below with reference to the accompanying drawings, to which reference is made for details not further mentioned in the description.

FIG. 1 shows a partial view of a sheet feeder;

FIG. 2 illustrates a partial side view of a sheet separator;

fig. 3 shows a perspective view of a separation module;

fig. 4 shows a view of the separation module from below;

FIG. 5 illustrates a partial view of a sheet separator having a plurality of identical separation modules;

fig. 6 shows a receptacle for a separation module.

Detailed Description

As shown in fig. 1, a housing space 34 for the sheets Zhang Duiduo is provided in the frame 3 of the sheet feeding apparatus. The receiving space is limited on the side by a carrier 33, for example a column. These columns, together with a longitudinal carrier 31 and a transverse carrier 32 arranged above the receiving space 34, which connect the columns to each other, constitute the basic frame of the machine frame 3.

In the frame 3, the sheet separating device is arranged above the stacks 7 to be separated. The sheet separating device separates the uppermost sheet 71 from the stack 7 and supplies the sheet to a transport device, not shown. The transport device receives the sheet and transports it away from the stack in the withdrawal direction 300.

The transport device receives the sheet in the region of the leading edge of the sheet, while the separating device also holds the sheet in the region of the trailing edge of the sheet. The feeding means 61 having a vertical feeding direction and acting on the separating device allows adjustment of the spatial handover conditions.

In the horizontal sheet-extracting direction 300, the separating apparatus can be positioned in the frame 3. The device can thereby be adjusted to the sheet length while the positioning of the preceding sheet edge is fixed. For this purpose, the separating apparatus is accommodated in the frame 3 by means of a feed device 51. The separating device can be positioned by means of the linear guides 52 mounted on the longitudinal carriers 31 of the frame 3, which are arranged on both sides of the accommodation space 34, by means of the transverse carriers 59 of the separating device. The feeding device 51 comprises a clamping portion 55. The clamping 55 holds the separating device in position relative to the preceding sheet edge.

The separating device is arranged in the region of the trailing edge of the stacked sheets 71, 72. In order to facilitate its positioning in the longitudinal direction 300, a stop 54 is provided on its transverse carrier 59. When the specification is set manually or after insertion of the stack 7 into the receiving space 34, the separating device can be moved into the region of the rear edge until it rests against the rear face 74 of the stack 7 by means of the stop 54. This position is then fixed by operating the clamping portion 55.

The separation device is constituted by a plurality of identical separation devices 1. They can each be positioned along a linear guide 60 extending transversely to the extraction direction 300. The lateral stop 53 limits this adjustment area, which is guided to the side of the stack 7.

Other descriptions may refer to one of the many identical separation devices 1, provided that there are no other distinguishing features.

The separating device 1 has at least one suction element 11, for example an aspirator, which can grasp and hold the uppermost sheet 71 of the stack 7 by means of an adjustable underpressure. For this purpose, the suction means are directed perpendicularly to the upper face 75 of the stack 7. The aspirator is received by the first feeding means 12. The first feeding device presets a vertical feed direction for the suction device in order to lift the uppermost sheet 71 at least in the region of the trailing edge of the sheet and thereby remove it from the stack 7. For the lifting movement of the aspirator, the feeding device 12 is configured with a size specification of the order of centimeters. Which is itself integrated in each aspirator.

The separating devices 1 shown in fig. 1 and 5 each comprise two identical suction systems. In this case, each aspirator is assigned a separate controllable valve in its supply line 13. Whereby each aspirator can be operated individually. Nevertheless, the control of the various aspirators is performed by means of a common controllable valve in order to ensure time synchronization during operation. By switching the suction units on or off, the separating device can be adapted in a simple manner to the specifications and/or characteristics of the sheets 71, 72 to be separated.

The uppermost sheet 71 is not separated from the following sheet 72 by the aspirator alone with sufficient reliability by various physical effects such as aspiration, adhesion, and the like, and materials and environments. Instead, separation can occur undesirably between a plurality of subsequent sheets 72 in the upper region of the stack 7. In order to reliably separate only the uppermost sheet 71 from the stack 7 at all times, the separating device is provided with a sheet separating device 2 in addition to the separating device 1.

The sheet separating devices 2 are all identical in construction. The description hereinafter with reference to fig. 3, 4, 6 refers to any one of the sheet separating apparatuses 2 as long as there is no other special content.

In the case of separation, the separating device 2 supports the separating device 1 and serves to cause a separation step of the sheets 71, 72, which is initiated by the separating device 1, to occur between the uppermost sheet 71 and the sheet 72 directly adjoining it. For this purpose, the separating device 2 is directed substantially toward a vertical surface 74 of the stack 7, which is formed by the following sheet edge.

The separating device 2 has a restraining element which mechanically acts on the trailing edge of the sheet 72 directly adjoining the uppermost sheet 71. The restraining element resists the tendency of the following sheet 72 to adhere to the uppermost sheet 71 to be separated. Brush 28 has proven suitable as a restraining element. They reliably support the separating step and do not cause sheet damage, unlike the knife edge. The separating device 2 shown in the figures has two such brushes 28 as restraining elements.

As shown in fig. 2 and 3, the bristles of brush 28 are positioned opposite the separation direction for further process reliability. The brush 28 is accommodated in the frame 21 of the separating apparatus 2 such that its bristles leave the horizontal and are oriented slightly downwards.

The frame 21 of the sheet separating device 2 is embodied in multiple pieces. The first part frame 211 is used for the mounting of the separating apparatus 2 in the frame 3. The second partial frame 212 accommodates the brush 28 as a restraining element. The second partial frame is connected to the first partial frame 211 in such a way that the two partial frames 211, 212 can be positioned relative to one another for adjustment. For this purpose, a feed device 23 is provided.

The feeding device 23 has a horizontally oriented linear guide 231. The position of the restraining element relative to the subsequent page Zhang Lengbian can thus be individually positioned. This position is defined by the spindle drive 222 being arranged parallel to said linear guide 231. The pressure spring 203 threaded on the spindle 222 excludes thread clearances. Thereby, the spindle 222 need not meet the particular requirements of accuracy.

The frame 21 has a fastening portion 29 by means of which the frame is fastened replaceably in a receptacle 57 shown in fig. 6. The receiving portion 57 of the frame 21 is arranged on a lateral carrier portion 59 of the separating apparatus by means of a linear guide 56. Not only the separating device 1 but also the separating device 2 are arranged on the same transverse carrier 59. The separating device 1 and the separating device 2 can thereby be adjusted together in the withdrawal direction 300 to the sheet format.

The fastening portion 29 of the frame 21 is connected to the first part frame 211 by another feeding device 22. The feeding device 22 has a vertically oriented linear guide 221. Whereby the frames 21 can be oriented individually perpendicular to the machine frame 3 by means of restraining elements. If the feed direction is not taken into account, the vertical feed device 22 is configured as a horizontal feed device 23 of the frame 21 and will therefore not be described further.

The blow nozzle is accommodated in said second part frame 212. The blow nozzle is directed towards the trailing edge of the upper sheets 71, 72 of the stack 7. The blown wind on the one hand supports the blocking of the following sheet 72. The blown air forms an air bed between the sheet 71 to be separated and the sheet 72 directly connected thereto. Not only the separation but also the transport of the separated sheets is thereby simplified.

The blow nozzles of the separating device 2 are configured as fan nozzles 26. Air escaping onto one face supports separating sheets of a particular size. The fan nozzle 26 is accommodated in the second partial frame 212 by the feeding means 24. The feed device 24 has a pivot axis 101 oriented substantially parallel to the trailing sheet edge. Whereby the blow nozzle 26 is movable in pitch 301 and the angle of the air fan relative to the sheets 71, 72 and the angle of the bristles of the brush 28 are adjustable in the sagittal plane.

The feeding device 24 for the pitch 301 can be kept very simple and compact both in its structure and in its operation. The pivot shaft 101 is constructed by a bolt 205. The second side plates 202 of the second partial frame 212 and the receiving portions 262 of the pitching movement means 24 therebetween are strung on the bolts. Furthermore, a pressure-elastic element is arranged on the shaft 101. By this, the prestressing force and thus the displacement difficulty about the pitch axis 101 can be adjusted steplessly by the tightening torque of the screw 205. In this case, in an embodiment according to fig. 3 and 4, springs 204, for example, a stack of coil springs, are provided as pressure-elastic elements on both sides of the second partial frame 212.

A holder 261 of the compressed air nozzle 26, which is pivotable about the vertical axis 102, is provided in turn on the receptacle 262 of the pitching device 24. Whereby the compressed air nozzle is capable of a deflection movement 302. The configuration of the feeding device 25 for the yaw movement 302 corresponds to the feeding device 24 for the pitch movement 301, which is described here with reference.

The two feed devices 24, 25 with the feed movements 301, 302 about the transverse axis 101 or the vertical axis 102 in particular together make possible a very versatile, simple controllable adjustment for the air flow from the air blowing nozzle 26 acting on the upper sheets 71, 72 of the stack. The containment element 28 and the blowing nozzle 26 are accommodated in a common, exchangeable frame 21, which makes possible a very compact and versatile design which can be adapted to the materials 71, 72 to be separated and to the characteristics of the stack 7. These advantages are apparent in particular when separating sheets 71, 72 having an offset rectangular profile or when separating sheets 71, 72 having an offset flatness.

In addition, the blowing nozzle 26 is rotatably accommodated in its holder 261 about its longitudinal axis 103. In the holder 261, the angular position of the fan nozzle 26 about its rotation axis 103 can be fixed by a clamping portion. The unintentional rolling movement 303 can be excluded in this case with simple adjustability. Whereby the blow nozzle is likewise pivotable and adjustable about its three axes 101, 102, 103. In particular when using the fan nozzle 26, the rolling movement 303 of the nozzle is advantageous in order to be able to adjust the plane in which the blowing wind contacts the stack 7 as well as possible.

An elastic restraining element 27, such as a spring tongue, is provided in said second part-frame 121. The spring tongue is oriented in its longitudinal direction parallel to the sheet withdrawal direction 300. Which is movable in the extraction direction 300. For this purpose, the spring tongue is accommodated by the slot 272. For simple handling, the end of the spring tongue facing away from the stack 7 is configured as a grip 271. Whereby the spring tongue can be positioned such that it protrudes or retracts with respect to the restraining element.

The spring tongue can be used as a presser in cooperation with the vertical feed 22 of the frame 21. The spring tongue limits the extent of the air bed between the sheet 71 to be separated and the sheet 72 directly adjoining it, which is produced by the air blow nozzle 26. Such restrictions stabilize the generated air bed, especially when the sheet gauge is large, and thereby contribute to an improvement in process reliability.

The construction of the sheet separating device 2 and its accommodation in the frame 3 make possible the individual positioning of the restraining elements and the blow nozzles (around and on all three spatial axes) when a plurality of such separating devices 2 are applied simultaneously. In this way, inaccuracies in the trailing edges of the sheets 71, 72 to be separated can be counteracted in an ideal manner. Because in practice, it is particularly common for the sheets 71, 72 to be wavy or to have cutting errors, the device described can significantly increase the process reliability in separating them from the sheet stack 7.

The sheet separating device 2, which is pre-adjusted to the respective sheet quality, can be stored in particular for further use and as required. The effort for adjusting the separating device can thereby be significantly reduced.

List of reference numerals

1. Separation device

2. Sheet separating device

3. Rack

5. Frame

7. Page Zhang Duiduo

11. Suction device

12. Feeding device

13. Suction line

14. Valve of aspirator

15. Linear guide

21. Frame

22. Vertical feeding device

23. Horizontal feeding device

24. Pitch feeding device

25. Deflected feeding device

26. Fan nozzle

27. Spring tongue

28. Brush with brush body

29. Fastening part

31. Longitudinal bearing part

32. Transverse bearing part

33. Column

34. Stack accommodating space

51. Feeding device

52. Linear guide

53. Side stop

54. Rear stop

55. Clamping part

56. Linear guide

57. Housing part

58. Lifting table

59. Transverse bearing part

60. Linear guide

61. Main shaft transmission mechanism

71. The uppermost sheet

72. Subsequent sheets

73. Accommodation site

74. Vertical face

75. Horizontal plane

101. Pitch axis

102. Deflection shaft

103. Rolling shaft

201. First side plate

202. Second side plate

203. Pressure spring

204. Coil spring stack

205. Bolt

206. Compressed air pipeline

211. First part frame

212. Second part frame

221. Linear guide

222. Main shaft

223. Hand wheel

231. Linear guide

261. Retainer

262. Housing part

271. Handle grip

300. Direction of drawing

301. Pitching

302. Deflection of

303. Roll-over

304. Lifting movement

Claims

1. Device for separating uppermost material sheets (71), the material sheets (71) being separated by stacks (7) of substantially flexible material sheets (71, 72), the device having at least

characterized in that the at least one sheet separating device (2) has at least one frame (21), wherein the at least one blow nozzle (26) and the at least one elastic restraint element (28) are arranged on a common frame (21).

2. The apparatus according to claim 1, characterized in that at least one third feeding device (22, 23) is provided in the frame (21) of the at least one sheet separating device (2), which third feeding device has at least one first linear guide (221, 231), wherein the first linear guide (221, 231) defines a feeding direction, and that the at least one third feeding device (22, 23) is operatively connected with the at least one blow nozzle (26) and/or the at least one elastic restraining element (28), such that the third feeding device (22, 23) determines the position of the at least one blow nozzle (26) and/or the at least one elastic restraining element (28) along the at least one first linear guide (221, 231).

3. The apparatus according to claim 1, characterized in that at least one fourth feeding device (24, 25) is provided in the frame (21) of the at least one sheet separating device (2), which fourth feeding device has at least one rotational bearing, wherein the rotational bearing defines a pivot axis (101, 102) and the at least one fourth feeding device (24, 25) is operatively connected with the at least one blow nozzle (26) and/or the at least one elastic restraining element (28) such that the fourth feeding device (24, 25) determines the rotational position of the at least one blow nozzle (26) and/or the at least one elastic restraining element (28) about the at least one pivot axis (101, 102).

4. The apparatus according to claim 2, characterized in that at least one fourth feeding device (24, 25) is provided in the frame (21) of the at least one sheet separating device (2), which fourth feeding device has at least one rotational bearing, wherein the rotational bearing defines a pivot axis (101, 102) and the at least one fourth feeding device (24, 25) is operatively connected with the at least one blow nozzle (26) and/or the at least one elastic restraining element (28) such that the fourth feeding device (24, 25) determines the rotational position of the at least one blow nozzle (26) and/or the at least one elastic restraining element (28) about the at least one pivot axis (101, 102).

5. The apparatus according to any one of claims 1-4, characterized in that the at least one frame (21) has an at least two-piece construction, wherein a first partial frame (211) is connected to the machine frame and the at least one blow nozzle (26) and/or the at least one elastic restraining element (28) are arranged in at least one second partial frame (212), and wherein the at least one second partial frame (212) is connected to the at least one first partial frame (211) by means of the at least one third feed device (22, 23) and/or by means of at least one fourth feed device (24, 25) such that the at least one third feed device (22, 23) defines a relative position of the at least one second partial frame (212) with respect to the at least one first partial frame (211) and/or the at least one fourth feed device (24, 25) defines a relative orientation of the at least one second partial frame (212) with respect to the at least one first partial frame (211).

6. The apparatus according to any of the claims 2-4, characterized in that the actuation force in relation to the at least one feed direction and/or the actuation moment in relation to the at least one pivot axis (101, 102) is greater than the inertia force generated by operation acting in the same at least one feed direction and/or the inertia moment acting around the same at least one pivot axis (101, 102).

7. The device according to claim 5, characterized in that the actuation force in respect of the at least one feed direction and/or the actuation moment in respect of the at least one pivot axis (101, 102) is greater than the inertial force generated by operation acting in the same at least one feed direction and/or the inertial moment acting around the same at least one pivot axis (101, 102).

8. The apparatus according to any one of claims 3-4, characterized in that at least one third feeding device (22, 23) and/or the at least one fourth feeding device (24, 25) has at least one spring (204), wherein the at least one spring (204) has a prestressing force and the prestressing force determines the starting force and/or the starting moment of the at least one third feeding device (22, 23) and/or the at least one fourth feeding device (24, 25).

9. The apparatus according to any one of claims 1-4, characterized in that at least one blow nozzle (26) of the at least one sheet separation device (2) is configured as a fan nozzle having a central blow-out direction, and in that the blow nozzle (26) is pivotally accommodated in a frame (21) of the at least one sheet separation device (2) about a rotation axis (103), wherein the rotation axis (103) is substantially parallel to the central blow-out direction of the blow nozzle (26).

10. The apparatus according to any one of claims 1-4, characterized in that the at least one sheet separating device (2) has at least one second elastic restraining element (27), which is at least at times arranged substantially above the uppermost sheet of material (71) and directed towards a horizontal surface (75) of the upper part of the stack (7), and in that at least one region of the second elastic restraining element (27) upwardly constrains the stack (7).

11. The apparatus according to any one of claims 1 to 4, characterized in that at least one lifting device arranged below the stack (7) has at least one vertically movable lifting element (58), wherein the at least one lifting element (58) limits downwards the space of the frame (3) accommodating the stack (7) of material sheets (71, 72) and the stack (7) of material sheets (71, 72) is placed on the at least one lifting element (58).

12. The apparatus according to any one of claims 1 to 4, characterized in that the frame (3) has at least one second linear guide (56) extending substantially transversely to the withdrawal direction (300), wherein at least two sheet separating devices (2) of the same type are individually positionable along the second linear guide (56).