DE2138420B2 - CUTTING DEVICE FOR TAPE-SHAPED MATERIAL - Google Patents

Description

The invention relates to a cutting device for ind-shaped material, in particular for strips of Photo paper with exposed and developed copies with a step-by-step feed device and a knife assembly containing a movable, paraüe! guided running knife and at least one stationary counter knife, the running knife with at least one projection outside the width of the strip to be cut permanently on the counter knife is present, has a cutting edge inclined to the direction of movement and one of the two knives is resiliently pressed against the other.

Such a cutting device is from the US patent 32 18 918 known. However, this device is not capable of a so-called double cut to be carried out to remove the edge area or overlap area between two successive ones Images on a strip.

Furthermore, it is known from the German patent specification 4 41 948 a cooperating with a fixed knife To design the cutting knife like a roof edge in order to move the one to be cut laterally Avoid material during the cut with a sloping cutting edge.

In cutting devices of the type mentioned, there is a fundamental difficulty in the Manufacture knives with the required accuracy In the case of knives that are to be made relatively thin in particular the running knife, which must be hardened to achieve a high cutting performance, the hardening delay represents a particular problem. Em such delay can also be caused by a subsequent Grinding with magnetic clamping cannot be compensated because the knife is being clamped elastically deformed. This deformation disappears immediately after the clamping force ceases, so that the delay that has occurred is retained. The requirements for the flatness of the knife can however, considerably reduced by the resilient compression of the two knives during the cut will.

The object of the invention is to design a cutting device of the type mentioned in such a way that also for a so-called punching or double cut the knives for high cutting edges with regard to their Flatness only need to meet requirements of a reasonable size

This object is achieved by the invention described in claim 1 below.

Since the second counter knife is already on the projection of the running knife before the start of the cutting process is applied, the running knife is immersed between the two counter knives without constraint possible. Due to the roof-shaped cutting edge, the running knife and the two counter knives each touch because only along relatively short lengths, so that the three knives are scissor-like due to the resilient contact slide together with the cutting clearance 0. By offsetting the cutting edge of the second or downstream th counter knife opposite the cutting edge of he most counter knife down is also with a roll tendency or a sagging of the paper band under its own weight is always a perfect one He ensures that the leading edge of the paper is fed over the second counter knife.

The invention is described in the following description of an embodiment, on the basis of figures explained. It shows

F i g. 1 a cutting device according to the invention ii the view against the direction of tape transport

F i g. 2 the device according to claim 1 in side view and

F i g. 3 shows an enlarged section through the cutting device according to FIG. 1.

In Fig. 1, 1 denotes a movably arranged running knife which, in the area of a strip 2 to be cut, has a cutting edge la running obliquely to its direction of movement according to arrow 3. In order to avoid a lateral force on the η cutting band 2, the cutting edge la is sloping on both sides, that is to say formed like a roof edge. The running knife 1 is, as shown in FIG. 3 it can be seen, with its upper part in a gap 4 between guide plates 24 and 25 guided approximately free of play, the width of which is set by spacer bushes 5 on screws 6 with nut 7. From Fig. 3 it can also be seen that the running knife 1 has a hollow grind in the area of the cutting edge la, so that the knife is able to perform a so-called punch cut when using two counter knives 8 and 9, ie cut a narrow strip out of the tape.

The running knife also has two downwardly directed projections \ b in its edge area outside the width of the strip to be cut. Ic, which are constantly in contact with the counter knives 8 and 9.

The running knife also has bores IJ, Ie on its side edges, in which pins 10a, \ Qb of a bracket 10 engage, which in a known, not shown manner with a drive for the Laufme <: ser, z. B. is coupled with an eccentric to a motor executing one revolution per cut. The arms of the bracket 10 also take over the lateral guidance of the running knife 1, so that this can adjust itself to a position free of lateral forces.

In particular from FIG. 3 the arrangement of the counter knives £ and 9 can be seen. The cutting edges of the knives 8a and 9a of the counter knives run in a straight line and the knives have a rounding on their lower boundary surface 8b and 96, respectively. With this rounded surface they sit on supporting surfaces of a support body 11 or a removable counter knife unit 12 that are fixed to the device Way prevents the knife from being pulled out of its holder without play. Finally, just below the upper edge of the knife is a rubber hose 15 in a groove 16a of a displaceably arranged holding plate 16. The z. B. realized by means of elongated holes on fastening screws adjustability of the plate 16 is used to regulate the pressure of the hose on the knife 8. The material of the rubber hose is not subject to any special requirements, since most types of rubber have the required elasticity without embrittlement at the prevailing temperatures for the periods in question. The rubber hose takes on the further essential function of preventing dust from penetrating into the gap between the carrier body 11 and the counter knife 8, which would very quickly impair the mobility of the counter knife.

The holder for the second counter knife 9 corresponds in terms of securing against removal and the suspension of the arrangement of the counter knife 8, but this is due to a different adjustment option the holder for the resilient rubber hose 17 is not designed to be displaceable.

The holder 12 for the second counter knife 9 is by means of two knurled screws 18, 19 on the carrier body 16 releasably attached. A conversion from single cut to punch cut is therefore very quick Time feasible. It is important that the cutting edge of the counter knife 9 is opposite that of the counter knife 8 is offset downwards by a small amount, about 1/6 the thickness of the running knife. By

ίο this offset prevents the advanced Band material! 2 after overflowing the cutting edge of the counter knife 8 by a tendency to roll or scm Its own weight drops so far in relation to the cutting edge of the knife 8 that it is at the cutting edge of the

ic genmessers 9 hits. The offset is therefore dimensioned in such a way that that such a bump is avoided in any case. On the other hand, the offset is small enough. to ensure that the cut on the counter knife 9 has already started before the cut on the Knife 8 is finished, which by appropriately dimensioning the height of the roof edge of the running knife 1 without anything else is possible. In Fig. 2 are also given in a known manner driven transport rollers 20, 21, which, due to an intermittent rotary movement, pull tape material from a roll 22 and put it in feed the required lengths to the cutting device.

The mode of operation of the device described is now as follows:

The band 2 conveyed step by step by the rollers 20, 21 is brought to a standstill in the cutting position between the running knife 1 and the counter knives 8, 9. Then, by eccentric drive of the bracket 10, the running knife 1 is guided in parallel downwards. The running knife is in this case with the projections \ b and Ic, depending on whether it is a single cut or a punching cut, already resiliently on the counter knife 8 or on both counter knives 8 and 9. During the movement of the running knife 1 downwards, each of the two knives 8, 9 is therefore pressed against the spring force of the hoses 15, 17 so far outwardly by the running knife that the cutting edges just abut one another. In the case of the roof edge shape of the running knife, such a system takes place in two very narrow areas of each counter knife which are arranged symmetrically to the axis.

If the cutting edge of the running knife has reached the band 2, the band is clamped on both sides. Since the slope angle of the roof edge is smaller than the critical angle for the self-locking, can a shift of the band 2 with respect to its support surface does not take place, which is the case with the symmetrical Formation of the knife could only be noticeable as a bulge. The tape then becomes continuous cut on both sides from the edges towards the middle until they are completely separated. After completion of the cut, the running knife returns to its rest position according to FIG. 1 back and the cut off part of the tape falls in FIG. 3 to the right of the counter knives in a designated, not shown Drip tray.

It is also important that the springing of the two counter knives on the running knife causes a Results in clearance angle, which can be between 1 and 6 ° depending on the design, but a size of about 3 ° should strive for. This clearance angle guarantees a perfect cut even at very high Cutting performance, because this means that the

Cutting edge and a build-up of the area behind the edge can largely be avoided. Further is in a punch cut through the gap between the counter knives 8, 9 ensured that the punched-out strips fall away downwards, so that the The counter knife always remains movable according to the F.

The cutting device described is their materials than paper, e.g. B. Movies mi Fen and the like. Applicable, which are considerably tough.

For this purpose 3 sheets of drawings

Claims (8)

Patent claims: 1. Cutting device for tape-shaped material, in particular for tapes made of photographic paper with exposed and developed copies with an incremental feed device and a Knife arrangement, containing a movable, parallel guided running knife and at least one stationary Counter knife, the running knife having at least one protrusion outside the width of the tape to be cut is constantly in contact with the counter knife, one inclined to the direction of movement Has cutting edge and one of the two knives is resiliently pressed against the other. through this characterized in that a second resiliently attached behind the running knife in the direction of tape advance the running knife pressed-on counter knife is provided for a so-called punch cut, the The cutting edge is offset downwards from the cutting edge of the first counter knife. 2. Cutting device according to claim 1, characterized in that the running knife (1) like a roof channel formed with two-part sloping cutting edge (la) compared to the counter knife and with is provided with a hollow ground. 3. Cutting device according to claim 1 or 2, characterized in that the running knife (1) in a gap of appropriate width is guided almost free of play perpendicular to its plane and that the lower counter knife (8, 9) preferably with a rounded lower support surface (86; 96) is pivotably mounted on this lower support surface and by an elastic member, in particular a rubber hose (15, 17) is pressed against the running knife (1). 4. Cutting device according to claim 3, characterized in that the counter bearing (16) of the Hose (15) is displaceable to adjust the suspension. 5. Cutting device according to claim 1, characterized in that the holder (12) for the second counter knife (9) is designed to be removable. 6. Cutting device according to one of the preceding claims, characterized in that the counter knife (8,9) with respect to the movable knife (1) a clearance angle of 1 to 6 °, in particular 3 °. 7. Cutting device according to one of the preceding claims, characterized in that the counter knife (8, 9) each have at least one bore (8c) into which the adjustable, a lifting of the Engage claws (14) preventing the counter knife. 8. Cutting device according to one of the preceding claims, characterized in that the running knife (1) has two downwardly directed projections (16, Ic) and two openings (id, Xe) located outside the tape path, in the pins (KOa, 106) of a bracket (10) connected to the knife drive engage.