DE2917937B2 - Cross cutter with at least one rotating knife roller - Google Patents

Description

The invention relates to a cross cutter with at least one rotating knife roller according to the

ίο preamble of claim 1.

Such a cross cutter is known from DE-PS 18 08 981. With him one should Support of the knife rollers in their loading phase, d. H. at the moment of the cut, can thereby be achieved that a segment-shaped projection is arranged opposite the knife, which cooperates with support rollers. The segment-shaped projection only extends over a very short circumferential area of approx. 90 °. In another embodiment, a cam cooperates with the knife roller so that a Support for the knife roller is formed.

For the same purpose, a support device is provided in DE-AS 24 44 704 for the upper knife roller, which consists of two shafts driven synchronously with the knife roller, on which cam disks run around, which have cutouts of approx. 90 ° in order to let the knife pass in between. These too are only intended to support the knife during the cut.

From US-PS 22 38 542 such an embodiment is apparent in the synchronously driven Support rollers are provided on the upper and lower knife roller. They have cam-like protrusions which work together with the knife roller at the moment of the cut and make cutouts to the knife to let it happen.

Finally, from DE-AS 22 61 729 a device on a rotating cross cutter became known when on the knife roller

ίο Ring projections are provided, each in the middle are offset against each other in the upper and lower knife roller. However, they don't serve too a support, but are intended to bend the web to be cut into a wave shape to prevent that they deviate from their prescribed path.

The object of the invention is to provide a cross cutter of the type mentioned, which is through a improved support enables a more precise cut.

This object is achieved according to the invention by the characterizing part of claim 1.

Especially with cross cutters that are made from very wide Web had to cut small-format sheets, the problem arose that the knife rollers in comparison to their length have become too thin to allow precise knife guidance. This is how it came about an unclean cut and in extreme cases even damage to the knife. Through the invention the knife rollers, preferably in their central area, are all-sided and, in particular, against sagging and the resulting vibration phenomena supported and safely guided. One takes the The knife roller therefore has all degrees of freedom in the support area (apart from that of rotation) and thus has in terms of deflection and vibration phenomena, it is only half the length of the knife roller to be expected if a support is provided.

15th

20th

25th

30th

This reduces the deflection to a quarter. On the other hand, this makes it possible to use the To make the knife roller thinner and with less mass, which is particularly advantageous when the knife roller with during one .; Circulation driven at changing peripheral speed will. This can reduce the driving forces and machine vibrations.

In spite of the unusual measure, in spite of the resulting in the recesses for the knife If a roller guide is to be provided on all sides to a large extent, there are no vibration phenomena. As practice has shown In the prior art described, there has always been an effort to achieve the To let the knife roller run freely and only to support it briefly in the cutting moment in order to achieve a to absorb the existing load due to the resulting impact. On the other hand, the Invention the rollers are held in engagement so that they act like a central bearing and they are preferably so provided that even if a role does not work because of the knife recess overflowing, at least in the vertical direction a support by two support rollers offset from one another by less than 180 ° given is.

The raceways for the rollers can preferably protrude from the knife roller surface Ring projections may be provided. The track η are arranged so that the knife opposite them not protrude.

The respective counter knife engages in a recess in the track, which, however, is located limit the immediate area of the knife. The ring projections could be made from the material of the Knife roller must be worked out, but are preferably rings or rings placed on the knife roller. Ring segments. It is also possible, the ring projections each have a corresponding flat groove or Assign the recess on the opposite knife roller.

Instead of individual rolls, pairs of rolls can be provided which are arranged next to one another in the axial direction and whose points of contact in Circumferential direction of the knife roller are only a little apart. This creates a safe guide the knife roller is guaranteed in the corresponding direction even if the recess is just on the Pair of rollers passes by. One of the two roles is then always engaged. The roles of a Pair of rollers run side by side on the same ring projection

There are preferably at least 3, preferably 4, rollers or roller pairs over the circumference of the knife roller arranged offset from one another by at least 60 °. This measure becomes the all-round Storage ensured in an advantageous manner.

Further advantages and features of the invention emerge from the subclaims and the description in Connection with the drawings. It shows

Fig. 1 is a schematic section through an eo Cross cutter according to the line I-l in F i g. 2,

F ί g. 2 is a partially broken away view of a cross cutter in FIG. 1 seen from the right,

F i g. 3 shows a detail of a roller running on an annular projection in partial section.

The cross cutter 11 shown has a machine frame 12 in which two knife whales can be rotated zen 13, 14 are stored. In the example shown, the length of the knife rollers is, for example can amount to two meters, a relatively small diameter of 180 mm, for example. On theirs Circumference are each offset by 180 ° from one another, two knives 15 in a recess 20 by means IS clamping wedges attached. Those that run at an angle to the axis to create a pulling cut Knives protrude slightly above the normal surface of the knife rollers. One upper knife and one each ίο a bedknife work together with their cutting edges.

In the middle area of the knife rollers, rings 17, 18 are provided, which correspond to the area of revolving flat annular grooves 21 in the form of ring segments are fastened by screws 36 of the knife roller. Each ring segment comprises a little less than half the circumference of the knife roller, so that between the Ring segments form a gap or a recess 19, which the knife and the directly to the Cutting edge of the knife 15 leaves the adjacent area free.

The outer surface of the rings 17, 18 forms a running surface 22 and projects slightly over the circumferential surface the knife roller. From Fig. 2 it can be seen that in each case a ring has a flat annular groove 37 on the opposite to other knife roller. The two rings are located in the central area of the longitudinal extension of the Knife rollers next to each other and slightly overlap in the radial direction.

On the track 22 of each ring 17, 18 rollers 23 run, which are adjustable and rotatably attached to support arms 25 which are attached to the machine frame 12. In the example shown, six rollers are provided for each knife roller, four of the six rollers being combined to form roller pairs 24 whose points of contact on the raceways are only a small amount apart in the circumferential direction (between 5 ° and 20 °). In the example shown, the rollers 23a to 23f are provided for the lower knife, which, counting clockwise from the vertically upward direction (like the compass rose), are arranged in the following angular positions:

50

b5

role 23-a 90 " role 23 ί) 160 = role 23 c 170 ° role 23 d 220 ° role 23e 230 ° role 23 / " 300 °

The direction of paper travel (corresponding to the direction of rotation in the gap between the knife rollers) starts running from left to right.

For the upper cutter, the roll

23 ir 240 23Λ 260 23 / 315 23A: 20th 23 / 90 23 m 110

This arrangement has proven to be very advantageous, of course, can according to needs to be changed.

Di ^ pairs of rollers 24 of the narrow in the circumferential direction Standing roles overlap in the circumferential direction and therefore each run on the same track side by side. The other roles can either be in

the middle of the career or towards the middle of each The knife shaft also runs offset on one edge of the raceways 22.

The role of the rollers is to prevent the cutter shafts in the middle not only from cutting cold, but also against deflection forces as well as resulting therefrom de to store vibrations. The minimized storage also results in an increase in the critical rotational frequency. It is ensured that a three-point mounting is always created, in which Area where deflection would affect, i.e. H. in the lower area of each knife roller, always there is full support, d. H. that there the respective effective roles never more than 180 ° to be apart. By the roller pairs 24, which are each arranged in the lower region of the knife roller are, it is ensured that a safe leadership is given even if a role is just about a Recess 19 runs away.

The two pairs of double rollers 236, c and 23c /, e primarily serve to absorb the deflection of the lower knife roller, while the double roller pairs 23 ^, h and 23m and in a certain way also 23 / serve to absorb the deflection of the upper knife roller. The two first-mentioned pairs of rollers 23c / to e simultaneously also absorb the downwardly acting cutting pressure component of the lower knife roller 14. In addition to this vertical cutting pressure component, another important force component acts during the cut, namely a cutting pressure component acting essentially in the direction of paper travel on the upper knife roller, which is absorbed by rollers 23 / and 23m, while on the lower knife roller 14 a cutting pressure component acting against the direction of paper travel of the lower knife roller is taken up by rollers 23d, e and f . The cutting pressure component of the upper knife roller 13 acting upwards is taken up by the rollers 23 / and k . The knife roller 23a completes the three-point support of the lower knife roller 14.

Squeegees 33, 34, the latter, run along with the knife roller circumference and in particular on the running surfaces 22 a preliminary squeegee 35, which ensure that no just cut sheet sticks to the knife roller, pulled up or down on it becomes and gets under the roles. Also, the leading edge markings are on the sheet and a too Avoid hanely putting on the roles.

From F: g. 3 is a roller 23 in cooperation with; nem Rmg 18 shown in detail. With the role it is a commercially available support roller with a roller or needle bearing 27, which is on a fixed, the axis 28 is fixed by means of a snap ring. The axis has a collar 29 in which yuerlöcher 30 are attached for adjustment.

A, ι "· <· η collar 29 is joined by an eccentric pin 31 on, which has a very small eccentricity of, for example, 1 mm with respect to the axis 28. This Eccentric pin is by means of a nut 32 in a

ίο Bore of a support arm 25 fixed. Using the Eccentric, the support roller 23 can be precisely adjusted in a simple manner in which, after loosening the nut 32 the setting is made with a tool inserted into a hole 30. The in Fig. 1 only arms 25 shown schematically can be used individually or for easier accessibility of the knife roller be swiveled away together.

It can be seen that a cross cutter is created by the invention, the knife rollers which are supported on all sides, "three-point", at every point in time of the rotation of the Knife roller.

The arrangement of the roles in detail can vary depending on the load conditions, but should care must be taken to ensure that the deflection forces are always absorbed. So should for example the angle 26, which is indicated on the upper knife roller 13, is always smaller than 180 ° be. This is also at least in the vertical downward direction when a recess 19 is the role 23m happened, given.

In the case of the lower knife side 14, when the rollers 23a or 23 / are passed, an angle occurs that is greater than 180 °, but no forces occur in this direction. It is possible through the invention to create a sheeter that has a very large continuous knife length without the knife rollers extremely thick. Above all, it is also possible to make the knife whales hollow, which means that their Mass is further reduced and its deflection is further reduced. It is preferred that the roles run on ring projections that protrude from the knife roller surface.

However, it is also possible to build the knife somewhat sunk into the knife roller as a whole. It is It is also conceivable to provide more than one support for particularly long and thin knife rollers or the individual rollers for the support according to special axial vibration conditions To be spaced from each other.

For this purpose 2 sheets of drawings

Claims (11)

Patent claims: 1. Cross cutter with at least one rotating knife roller with a low mass moment of inertia, which carries at least one cutting knife and cooperates with at least one counter knife the circumference of which is fixed to the machine, rotatably mounted rollers are specified, the at least have a supporting effect on the knife rollers at the time of cutting, characterized in that that the rollers (23) over the vast majority of the circumference of the knife roller these on running surfaces (22) so that the at least one knife (15) does not protrude radially beyond the running surfaces (22), that several rollers (23) are distributed in such a way over the circumference of the at least one knife roller (13, 14) are arranged that the circumferential distance of their points of contact from each other in the lower peripheral region of the knife roller (13, 14) less than 180 ° during the entire rotation of the knife roller is, and that pairs of rollers (24) are provided, the points of contact in the circumferential direction of the knife roller (13,14) are only slightly separated from each other. 2. Cross cutter according to claim 1, characterized in that the running surfaces (22) on of the Knife roller surface protruding ring projections are provided. 3. Cross cutter according to claim 2, characterized in that the annular projections of the Knife roller (13, 14) attached rings (17, 18) are formed. 4. Cross cutter according to claim 2 or 3, characterized in that an annular projection on one Knife roller (13,14) is assigned a flat annular groove (37) on the other knife roller. 5. Cross cutter according to one of the preceding claims, characterized in that the rollers (23) are arranged in the central area of the ixial extension of the knife roller (13, 14). 6. Cross cutter according to one of the preceding claims, characterized in that the rollers (23) of the roller pairs (24) are arranged next to one another in the axial direction. 7. Cross cutter according to one of the preceding claims, characterized in that the rollers (23) of a pair of rollers (24) run on the same ring projection. 8. Cross cutter according to one of the preceding claims, characterized in that over the Circumference of the knife roller (13, 14) at least three, preferably four rollers (23) or pairs of rollers (24) are arranged offset from one another by at least 60 °. 9. Cross cutter according to one of the preceding claims, characterized in that at two interacting knife rollers (13, 14) the roller raceways (22) in the axial Direction are arranged offset from one another and preferably overlap in the radial direction. 10. Cross cutter according to one of the preceding claims, characterized in that with the running surface (22) at least one doctor blade (33, 34, 35) cooperates, which is arranged in this way. that it from the knife roller (13.14) detaches any sheets that may have been carried along by the knife roller (13.14). 11. Cross cutter according to one of the preceding Claims, characterized in that the rollers (23), preferably via an eccentric bearing are adjustable.