DE4440582C1 - Method and appliance for chopping up cardboard, esp. corrugated paper - Google Patents

Abstract

The frame (18) mounted in a vertical guide (16) has at least one, pref. two, knife blades (30) with contrarily motor driven single blades. The single blades are driven towards each other under cyclical phase displacement. Their vertical movement is synchronously superimposed by a continuous horizontal movement. The speed of the vertical movement is a multiple of the horizontal movement which is synchronised with the movement of the conveyor belt (B). Eccentric drive mechanisms drive the blades inside a housing (51), with connecting rods of different lengths.

Description

The present invention relates to a method for cutting cardboard according to the preamble of claim 1 and a device for performing of the method according to the preamble of claim 7.

Bottles are usually packed in plastic boxes for transportation returned to the bottler after use. After the end However, these bottles packed in boxes abroad are not delivered mostly the return of the empty boxes because the return transport costs higher caused as a disposal on site. As a result, very high costs are incurred for the bottler Packaging costs.

To avoid this, bottles that are to be shipped abroad are len, packed in easy to dispose of, cheap cardboard boxes, with between the individual bottles a cardboard insert is used so that this during transport not be damaged. Due to the higher packing density of the bottles in the Carton also reduces the transport volume, which is beneficial to the Transportation costs.

When packaging, the bottles are on a tight grid Conveyor belt and are fed to a packaging machine. At the same time  an endless S-shaped cardboard insert between the individual rows of bottles placed so that the individual bottles can no longer collide. In front packing the bottles in a cardboard box, the cardboard inserts however, be cut according to the box size, which is conventional happens with electric hand knives. Because the cardboard used, mostly a single-ply corrugated cardboard, as quickly as possible vertically from top to bottom must be separated and the material in this direction its greatest resistance it is not possible, or only possible to a limited extent, to make a clean, straight cut to lead. The knives dull quickly and have to be changed often. In addition, this work is very exhausting and personnel-intensive, since it is business reasons, the highest possible belt speed is driven for which Separation process is therefore only available for a short time.

For dividing soft-pasty masses z. B. from DE-GM 93 08 956 a Known cutting device, the two knives held in a support frame has stations. The individual knives of the knife pairs are used during one downward cut from an eccentric drive with an eccentric shaft Back arm on the individual knives of the knife pairs in opposite directions to each other moved back and forth, their cutting edges being self-sharpening in pairs slide along. A lifting / lowering drive moves the support frame along Verti Kal-guided tours between a standby and a near-ground limited Working position. Such a device is not for cutting cardboard or only suitable to a limited extent. Firstly, there is the problem that both knives go through the eccentric arrangement come to a standstill in its reversal points and therefore no cutting movements during the vertical downward movement do more. The cardboard insert to be cut is simply torn or indented so that pressure or bulge arise, which a smooth and prevent continuous cutting. On the other hand, the knives blunt thanks to the abrasive-looking paper dust created during cutting from, especially at very high knife speeds, which also lead to can cause the knife edges to bend and thus become unusable.

DE-GM 72 28 006 also shows a cutting machine with one in the extension eccentric drive attacking a straight knife. An end of Knife is mounted on a crank disc while the other end is in one Slot is guided. This also turns the Stopping coming horizontal movement an additional vertical swivel  movement superimposed, which adversely affects the vertical downward movement of the Knife affects.

The object of the invention is the vertical cutting of cardboard inserts with high Automate cutting speeds, which was the cutting device low-effort and with high operational reliability. In addition, the knives should have a long service life.

In a process for cutting cardboard, in particular corrugated cardboard, with a frame which is movably mounted in a vertical guide and which has at least one preferably two, knife swords with motor driven in opposite directions Carries individual knives, which are guided parallel through the cardboard from top to bottom and are pulled out after the cut upwards, the inventor sees tion that the individual knives with cyclical phase shift to each other are driven and that their vertical movement is uninterrupted Horizontal movement is superimposed synchronously. The phase shifted movement supply of the individual knives ensures that at least one of the knives, wäh Always make a cutting movement when cutting through the cardboard to be led. Steps between the individual knives and the cardboard to be cut thus no zero movement (standstill), because if one of the knives is When the reversal point is reached, the other is still in motion and leads one Cutting movement through. Even with an extremely high vertical cut The horizontal cutting speed of the individual knives can cause speed can be reduced many times relative to one another without the cardboard tearing or is pushed in. This in turn has a beneficial effect on the life of the Knife out; they only become moderately warm. Because of the synchronous overlay a horizontal movement with the vertical movement of the knives can clean, smooth and exactly vertical cuts are made. In particular In particular, cardboard can be continuously transported on a conveyor belt were easily and rationally divided without interrupting the material flow must be adjusted accordingly by the knife with the belt.

According to claim 2, the vertical travel speed is considerably greater than the horizontal, e.g. B. a multiple of the latter, which is a high cutting frequency guaranteed. By synchronizing the horizontal movement of the Knives on the movement of a conveyor belt according to claim 3 are in front geous way fluctuations in the belt or transport sub refractions taken into account. It is, as provided in claim 4, the band  speed much lower than the horizontal travel speed of the Knife. For example, they can overtake the belt and thereby several Make cuts one after the other.

According to claims 5 and 6, the individual knives of each knife sword self-sharpening guided along each other, between the individual knives compressed air is continuously fed with an oil admixture. These measures contribute significantly to a long service life and low maintenance. Ins In particular, the oil-air mixture advantageously prevents penetration of abrasive paper dust in the knife guide and between the individual meters ser.

In a cutting device according to claim 7, in particular for implementation of the method, according to the invention the individual knives of the knife swords are included a cyclic phase shift to each other, the verti an uninterrupted horizontal movement is superimposed synchronously. Because the individual knives always move relative to the cardboard due to the phase shift perform a cutting movement and never come to a standstill at the same time, the vertical cutting speed can be much higher than the horizontal Cutting speed of the individual knives. The knives have one extremely long service life and there are no cracks or beads in the Cardboard so that clean and smooth cuts are always made. The syn Chronically superimposed horizontal movement of the knife swords allows the end perform cuts even on moving objects.

Important constructive measures are given in claims 8 to 10. The drives of the knife swords are eccentric drives, whose vertices are angularly offset from one another, preferably by 8 ° and 10 °. Each eccentric drive preferably encapsulated within a housing has according to claim 9 connecting rods of different lengths, being in accordance with Claim 10 the shorter connecting rod, a longer single knife and the longer A shorter individual knife is assigned to the connecting rod. To be quick and pro The individual knives in the Development of claim 11 on the connecting rods from one side BEFE stigbar.

In an advantageous development, the knife drives are in one Number of rolling bearings, e.g. B. in seven roller bearings with reduced running clearance  stored, which achieves a significant reduction in noise becomes.

According to the important embodiment of claim 13, the knives are preferred made of high-alloy HSS tool steel, the cutting edges of the The individual knives of each pair are guided in a self-sharpening manner are. According to claim 14, they are preferably planar and pointed Angles of, for example, 3 ° are arranged obliquely to one another, so that the cutting which have an inner, preferably small, friction area which seals at the same time. Alternatively, the individual knife can each Knife swords according to claim 15 be slightly curved outwards. Is cheap the use of tool steel for the knives specified in claim 16 guides between which the individual knives are slidably mounted.

An important embodiment emerges from claim 17. After that they own Knife guides have a compressed air connection. Furthermore, according to claim 18 between Air guiding channels are arranged on the knife guides, in the simplest case grooves. On this is, as provided in claim 19, between those in the knife guides led single knife introduces a compressed air curtain with oil admixture. This causes constant lubrication of the knife blades and thus automatic Permanent maintenance. The penetration of abrasive paper dust into the knives leadership is effectively prevented.

So that the back edge of the knife sword when moving out of the zer cut cardboard with this not tilted, is according to claim 20 at the Mes a parting plate attached to each

For the detection of foreign bodies under the knives during a Cutting process is the electronic vertical drive according to claim 21 assigned cutting pressure monitoring. If necessary, the knives can be quickly automatically retract to the upper stroke position.

Further features, details and advantages of the invention result from the Wording of the claims and from the following description of Ausfüh Examples based on the drawings. In it show:  

Fig. 1 is a schematic representation of a cutting device,

Fig. 2 is a side view of a knife sword;

Fig. 3 is a plan view of the knife sword of Fig. 2,

Fig. 4 is a side view of an open blade guide,

Fig. 5 is a sectional view taken along line II of Fig. 4,

Fig. 6 is a sectional view taken along line II-II of Fig. 4,

Fig. 7a is a side view of an eccentric shaft,

Fig. 7b shows a side view of an eccentric bush,

Fig. 7C is a side view of a further eccentric bush,

Fig. 8 is a plan view of an open connecting rod drive.

The cutting device 10 shown schematically in FIG. 1 has a linear guide 12 arranged on a main support 11 , on which a carriage 14 driven by a motor 13 is mounted so as to be horizontally movable. This carries a linear guide 16 with a frame 18 designed as a slide, which can be moved vertically by means of a motor 17 . Two support frames 20 , each with a motor-driven knife sword 30 , are preferably fastened to the frame 18 and are arranged parallel to one another. A counterbalancing linkage 19 , as a counterweight, prevents the blades 30 from "pitching" during the up and down movement.

Each knife sword 30 has two individual knives 32 , 33 , which are slidably mounted in knife guides 37 and slide against each other in opposite directions during the cutting process, for which purpose an eccentric drive 50 is provided. The sword 30 is held by means of screws S on a sword saddle 31 which is mounted on the support frame 20 together with a housing 51 surrounding the eccentric drive 50 ( FIG. 2, FIG. 3).

As can be seen in FIG. 1a, the entire cutting device 10 is arranged with the main carrier 11 parallel to a (schematically indicated) conveyor belt B, on which bottles F to be packed between guide bars C are fed along the transport direction T to a packaging machine (not shown) . The webs C preferably have recesses D, the spacing of which corresponds to the spacing A of the knife swords 30 . An S-shaped cardboard insert P, for example a single-layer corrugated cardboard, is inserted between the bottles F standing on the belt in a tight grid spacing so that the bottles F cannot touch one another directly. The support frame 20 is screwed on a back plate 21 to the frame 18, in which 21 slots (not shown) are provided in the plate. Depending on the number of bottles F to be packed, the distance A of the knives can thus be varied so that different cutting distances can be set. Due to the right-angled arrangement of the linear guides 12 , 16 with respect to one another, the knife blades 30 can be moved into any position above the conveyor belt B. In particular, the cutting movement of the swords 30 can be adapted to the movement of the conveyor belt B.

As shown in FIG. 4, the individual knives 32 , 33 have elongated holes 34 and are slidably guided within the knife guides 37 on sliding blocks 41 , 42 which engage in the elongated holes 34 . One of the knives 32 , 33 preferably has on its inside a spacer strip 35 , for example in the form of a vapor-deposited ceramic strip, so that the knives 32 , 33 have some spacing in the upper region (shown in a greatly exaggerated manner in FIG. 5) and their outer oblique shape slide together wedge-shaped cutting edges 36 in an inner, flat friction area against one another, self-sharpening and sealing. The knives 32 , 33 are preferably made of high-strength HSS steel, which has a service life sufficient for cutting cardboard. The inclination of the individual knives 32 , 33 to one another can also be achieved, if a suitable material is used, by slightly arching them outward by heat treatment.

The knife guides 37 are each formed by two plates 40 , between which the sliding blocks 41 , 42 and an upper and a lateral spacer bar 44 and 45 are fastened. The plates 40 are preferably made of 1.5 mm thick VA steel and are firmly riveted to the sliding block 42 and to the spacer strips 44 , 45 . The use of rivets has the advantage that they can still be completely sunk into the relatively thin material without impairing the stability of the plates 40 . The outer surfaces of the knife guides 37 are thus exactly flat, so that no material can get caught on the rivets during cutting. The sliding block 41 , on the other hand, has two bores 43 and is firmly screwed together with the plates 40 to the sword saddle 31 by means of the screws S protruding therethrough, which overhangs the knife guide 37 as a whole (see FIG. 6). As a result, both the sliding block 41 and the knife guide 37 are securely and reliably attached to the housing 51 together with the sword saddle 31 . The arrangement of the seated in the elongated holes 34 sliding blocks 41, 42 as well as the width of the upper spacer bar 44 are dimensioned so that the blades 32, 33 rest with their knife back to the strip 44, and uniformly charged by this during the cutting operation will be. In this way, an optimal transfer of the cutting force to the knives 32 , 33 is ensured.

The sword saddle 31 is preferably made of an elastic material, e.g. B. polyethylene. This material dampens the transmission of oscillations or vibrations from the knives 30 to the housing 51 and, in the event of a crash of the knives 30 with the cardboard P or the conveyor belt B, absorbs the impact.

The upper spacer bar 44 has a groove 46 running parallel to the back of the knife through which an air-oil mixture, e.g. B. is blown via a compressed air connection 28 and / or an air channel 49 in the saddle 31 . This passes through openings 47 , which are open at the bottom and arranged at the level of the elongated holes 34 , to the sliding blocks 41 , 42 , which have oil grooves 48 . A certain amount of oil can always accumulate in these so that the sliding surfaces of the moving parts within the knife guide 37 are constantly lubricated. So that the air-oil mixture cannot escape upwards and to the side, the spacer strips 44 , 45 seal the knife guide 37 in these directions, the knives 32 , 33 having a step 39 at their free ends facing away from the sword saddle and the sealing strip 45 reach under. In this way, the air-oil mixture flowing through the channels 46 , 47 , 48 reaches the friction area of the cutting edges 36 downward and ensures reliable permanent lubrication and cooling. In order to prevent paper dust from getting between the knives 32 , 33 or into the knife guide 37 during the cutting process, the guide plates 40 , as shown in FIG. 5, lie flat against the knives 32 , 33 and the air-oil mixture is blown into channels 46 , 47 , 48 with overpressure.

The individual blades 32, 33 are with their the support frame 20 facing ends of connecting rod 60, hinged 61, which are mounted on an eccentric shaft 53 with ball bearing eccentric bushings 56, 57 (Fig. 4, Fig. 7a to 7c). This is driven by a (not shown) belt drive from a flanged to the eccentric housing 51 motor 55 . So that the individual knives 32 , 33 do not come to a standstill during the cutting process relative to one another, the eccentric bushes 56 , 57 are fastened on the eccentric shaft 53 at an angle. For this purpose, two offset grooves 54 are provided in their cylindrical surfaces, into which (not shown) drive springs are glued. These springs engage in grooves 58 , 59 arranged offset in the eccentric bushes 56 , 57 . The angular offset is, for example, 10 ° for the eccentric bushing 56, for example 8 ° for the eccentric bushing 57 , so that a total angular offset of 162 ° is produced (see FIGS. 7a, 7b, 7c). In this way, the individual knives 32 , 33 are driven with a cyclical phase shift to one another. Is z. B. the knife 32 in its turning point, the other knife 33 is moved further, so that both knives are constantly moving relative to each other. The knife sword 30 thus always performs a cutting movement during its vertical downward movement. The vertical cutting speed and thus the cycle frequency of the conveyor belt B can be set correspondingly high. With a cutting cycle of z. B. 30 to 100 cuts per minute, the speed of the eccentric shaft 53 may be, for example, between 1000 and 2000 rpm. In these areas, permanent and trouble-free operation is achieved and the conveyor belt does not have to be stopped or slowed down unnecessarily.

It can be seen in Fig. 8, that the individual blades 32, 33 of the knife sword 30 and the connecting rods 60, 61 is formed of different lengths, with a long knife 32 and a short connecting rod 60 and a short blade 33 and a longer connecting rod 61 with an Ball bearings 62 are interconnected. The long knife 32 and the long connecting rod 61 both have a longitudinal recess 38 and 64 , in each of which the threaded axis 63 of the corresponding ball bearing 62 of the connecting rod 60 or 61 engages, with a spacer between the short knife 33 and the long connecting rod 61 67 is present. Lock nuts 65 screwed onto the threaded axes 63 ensure a secure connection. Overall, the eccentric bearings 56 , 57 can be attached immediately next to each other on the eccentric shaft 53 , so that the space requirement of the eccentric drive is reduced to a minimum and the eccentric housing 51 can be dimensioned accordingly small. In order to facilitate the assembly of the knives 32 , 33 , the threaded axes 63 can also point in the same direction, so that the attachment can be carried out from one side.

It is expedient if the compressed air connection 28 is provided on the eccentric housing 51 . The air-oil mixture thereby passes both through the channels 46 , 47 , 48 , 49 into the knife guide and into the housing 51 itself, so that the eccentric drive 50 is also constantly lubricated. The operational reliability is increased.

At the beginning of the cutting process, the knife swords 30 are in a position above the cardboard P to be cut and the slide 14 of the linear guide 12 is accelerated to the belt speed by the motor 13 . If he has reached this, the drive 17 of the vertical slide 18 is used to make a first cut at a very high vertical cutting speed, the distance A between the knife blades 30 arranged in parallel cutting off exactly one packaging unit. It is advantageous here that the individual knives 32 , 33 continuously perform a cutting movement by the eccentric drive according to the invention and thus the cardboard P does not tear. The wear of the knife edges 36 is considerably reduced and the service life is extended accordingly. In order to ensure a complete severing of the cardboard insert P, it expediently sits on spacers (not shown). The knives can then be lowered briefly over the band B, for which purpose the cutouts D are present in the webs G.

Already when the knife 30 is raised , the horizontal linear slide 12 accelerates and overtakes the belt B, brakes to belt speed and carries out a next vertically directed cut. A top plate 23 attached to the knife swords 30 advantageously prevents the separated cardboard inserts from tilting with the backs of the knife swords ( FIG. 1), the height of the plate 23 together with the height of the knife sword preferably being greater than the height of the cardboard P. Each Depending on the length of the horizontal linear unit 12 and the number of bottles F of a packaging unit, further cuts can be made.

When the end of the linear unit 12 has been reached, the carriage 12 is moved back to the starting position at a very high speed, so that the cutting sequence can begin again. In order to achieve optimal cutting results, the sharpness of the knife edges 36 , the speed of the shaft 53 and the vertical cutting cycle must be coordinated. Good results are achieved, for example, with a medium sharpness of the knives 32 , 33 , a cutting cycle of 60 cuts per minute and a knife frequency of 1500 rpm.

For the movements of the knife swords 30 to be carried out at high speed, it is important that the weight to be moved by the linear slides 14 , 18 is as low as possible. For this reason, the support frame 20 and the housing are made of aluminum 51, wherein for further weight saving of recesses 25 in both the support frame 20 and are also provided in the housing 51st The connecting rods 60 , 61 can also be provided with further cutouts 26 . The motors 13 , 17 , 55 are cooled with compressed air in order to further increase operational safety.

The invention is not limited to one of the above-described embodiments, but can be modified in many ways. For example, a cutting device 10 , each with only one knife blade 30, can be arranged on both sides of the conveyor belt B, both of which simultaneously perform a vertical cut and thereby the bottles F, z. B. by pushing in the horizontal direction, align or fine position. This is particularly necessary when the falses F transported on the belt B have slipped out of their ideal position and have to be pushed together again before the cartoning. The packing density of bottles F in a carton can also be increased in this way. In order to increase the cutting performance, one can position a cutting device 10 with a plurality of knife swords 30 on the left and right of the conveyor belt B, all of which are aligned parallel to one another. The cutting devices 10 then make a cut one after the other and overtake each other by overlapping the knives 30 .

The phase-shifted movement of the individual knives can also be generated by two eccentric bushes 56 , 57 with different strokes. Instead of a common angularly offset eccentric drive, the connecting rods 60 , 61 can also be driven individually, for. B. each with its own motor with electronic speed control.

It can be seen that, according to the invention, for dividing cardboard, in particular corrugated cardboard, at least two knife swords 30 with counter-driven individual knives 32 , 33 are held parallel to one another in a vertically movable frame 18 . The individual knives 32 , 33 are moved back and forth in a phase-shifted manner by an eccentric drive 50 during a downward cut, with their cutting edges 36 sliding along each other in a sharpening manner. At the same time, their vertical movement is synchronously superimposed on a horizontal movement coordinated with the movement of a conveyor belt B. Compressed air with an admixture of oil is passed between the slide-guided individual knives 32 , 33 through air guide channels 46 , 47 , 48 arranged in the knife guides 37 .

All of the claims, the description and the drawing outgoing features and advantages, including design details, space Licher arrangements and procedural steps, both individually and in the various combinations be essential to the invention.

Reference list

A distance
B conveyor belt
C guide board
F bottles
P cardboard insert
S screw
T direction of transport
10 cutting device
11 main beams
12 linear guide (horizontal)
13 engine
14 sledges
16 linear guide (vertical)
17 engine
18 sledge / frame
19 compensating linkage
20 support frames
21 back plate
23 crown plate
25 , 26 recesses
28 Compressed air connection
30 knife sword
31 sword saddle
32 , 33 individual knives
34 slot
35 spacer bar
36 cutting edge
37 Knife guide
38 recess
39 level
40 plate
41, 42 sliding block
43 hole
44 , 45 spacer bar
46 Groove / air duct
47 breakthrough
48 oil groove
49 air duct
50 eccentric drive
51 housing
53 wave
54 groove
55 engine
56 , 57 eccentric bushing
58 , 59 groove
60 , 61 connecting rods
62 ball bearings
63 thread axis
64 recess
65 lock nut
67 spacer

Claims (21)

1. A method for cutting cardboard (P), in particular corrugated cardboard, with a frame ( 18 ) which is movably mounted in a vertical guide ( 16 ) and which has at least one, preferably two, knife swords ( 30 ) with oppositely driven individual knives ( 32 , 33 ) carries, which are guided in parallel from top to bottom through the cardboard (P) and pulled upwards after the cut, characterized in that the individual knives ( 32 , 33 ) are driven with a cyclical phase shift to one another and that their vertical movement is uninterrupted Hori zonal movement is superimposed synchronously. 2. The method according to claim 1, characterized in that the ver tical travel speed is significantly greater than the horizontal, z. B. a Multiples of the latter. 3. The method according to claim 1 or 2, characterized in that the horizontal movement of the knife ( 32 , 33 ) is synchronized with the movement of a conveyor belt (B). 4. The method according to claim 3, characterized in that the Belt speed is significantly lower than the horizontal movement speed of the knives. 5. The method according to any one of claims 1 to 4, characterized in that the individual knives of each knife sword ( 30 ) are slidably guided along each other. 6. The method according to any one of claims 1 to 5, characterized in that compressed air is mixed with an oil admixture between the individual knives ( 32 , 33 ) each knife sword. 7. Cutting device, in particular for performing the method according to any one of claims 1 to 6, characterized in that the individual knives ( 32 , 33 ) of the knife swords ( 30 ) with a cyclic phase displacement are movable relative to each other and that their vertical movement synchronously with an uninterrupted horizontal movement is superimposed. 8. The device according to claim 7, characterized in that the drives ( 50 ) of the knife swords are eccentric drives, the apices of which are angularly offset from one another, preferably by 8 ° and 10 °. 9. The device in particular according to claim 7 or 8, characterized in that each preferably within a housing ( 51 ) encapsulated eccentric drive ( 50 ) connecting rods ( 60 , 61 ) of different lengths. 10. The device according to claim 9, characterized in that the shorter connecting rod ( 60 ) is associated with a longer individual knife ( 32 ) and the longer connecting rod ( 61 ) with a shorter individual knife ( 33 ). 11. Device according to one of claims 8 to 10, characterized in that the individual knives ( 32 , 33 ) can be attached to the connecting rods from one side. 12. The device according to one of claims 7 to 11, characterized in that that the knife drives in a number of rolling bearings, e.g. B. in seven rolling bearings with reduced running play. 13. Device according to one of claims 7 to 12, characterized in that the knives ( 32 , 33 ) are preferably made of high-alloy HSS tool steel and that the cutting edges ( 36 ) of the individual knives ( 32 , 33 ) of each pair ( 30 ) are guided in a self-sharpening manner. 14. The apparatus according to claim 13, characterized in that the individual knives ( 32 , 33 ) of each pair are planar and are arranged obliquely at an acute angle of, for example, 3 ° to one another and that the cutting edges ( 36 ) have an inner, preferably planar, friction area. 15. The apparatus according to claim 13, characterized in that the individual knives ( 32 , 33 ) of each pair ( 30 ) are slightly curved outwards and that the cutting edges ( 36 ) have an inner, preferably flat friction area. 16. The device according to one of claims 7 to 15, characterized in that the individual knives ( 32 , 33 ) are each slidably mounted between knife guides ( 37 ) preferably made of tool steel. 17 Device according to claim 16, characterized in that the knife guides ( 37 ) have a compressed air connection. 18. The apparatus according to claim 16 or 17, characterized in that between the knife guides ( 37 ) air guide channels ( 46 , 47 , 48 ) are arranged. 19. Device according to one of claims 16 to 17, characterized in that between the in the knife guides ( 37 ) guided individual knives ( 32 , 33 ), a compressed air curtain with oil admixture can be introduced. 20. Device according to one of claims 7 to 19, characterized in that a crown plate ( 23 ) is attached to the knife guides ( 37 ). 21. Device according to one of claims 7 to 20, characterized in that the vertical drive ( 17 ) is associated with an electronic cut pressure monitoring.