EP0275909B2 - Slitting machine for longitudinally slitting webs of films - Google Patents

Description

The invention relates to a method for cutting film webs with abrasive layers.

Foil sheets, especially coated Sheets for photographic and magnetizable Materials are processed in a Sheet of narrow bands cut lengthways. Among the slitting processes is the circular knife cut most common. Circular, arranged on corresponding knife shafts Upper and lower knife together. It is an execution became known in which the circular Upper knife (disc knife) in the shoulder of a circular lower knife (grooved knife). When cutting foils with abrasive layers For example with iron oxide or chromium dioxide coated magnetic tapes, the cutting edges very heavily abraded, with advanced Use the disc knife in that Grooving knife digs in. If the edge wear increases, for example in the order of the film thickness, the knives begin to squeeze shut cut, which results in poor cut quality. This is expressed in a bending of the cut edges from what happened during the subsequent winding of the tapes leads to uneven tape winding. In these cases need the knives out of the cutters exchanged and reground to get a sharp cutting edge again. The Disadvantages, which are for a rational use of the Cutting device from repeated insertion and Removal of the knives revealed are obvious.

An improved cutter that provides significantly longer service life for the knives. is known from DE-A-24 05 849 .; It comprises several disk knives rotatably mounted on a shaft and a corresponding number of cylindrical grooving knives rotatably mounted on a shaft. In doing so, as can be seen from FIG. 1, a disc knife (1), which is connected to the cutting shoulder by a disc spring (4) (2) of a slot knife (3) is pressed, something deeper than the thickness of the cutting shoulder. A However, the disadvantage of this device is that by the progressive removal of the cutting shoulder of the slot knife the contact surface of the to be cut Foil web is getting smaller as the gap width (b) gets bigger and bigger, which causes the cut quality to suffer. In addition, the contact pressure of the disc springs due to wear of the cutting shoulders during of the company are continuously adjusted.

From the IEEE-Transactions on Magnetics, Vol. Mag. 16, No. 1, January 1980, page 83, paragraph 2.13, a cutting system is known in which the disc knife without resilient elements rigid on the Disc knife shaft are attached. The contact pressure the disc knife to the cutting shoulders of the Grooving knife is made by elastic deformation of the Disc knife self. However, this device has a serious disadvantage: due to inaccuracies in the geometry of the disc and slot knives and the spacers between them the contact pressure of each disc knife can the associated grooving knife may be different, whereby one has to consider that often more than 100 cutting units sit on a knife shaft. Thereby results, as tests with this device show have one that changes from stripe to stripe Cut quality and by the required high axial contact pressure wear the knives very much fast.

Therefore there was the task of a cutting process to find which does not have the above disadvantages has and in particular a long Service life of the disc and grooving knives, before the knives need to be reground.

Figur 1 einen Querschnitt durch eine Schneidevorrichtung gemäß dem Stand der Technik

Figuren 2 und 3 Querschnitte durch eine Schneidevorrichtung zur Durchführung des Verfahrens gemäß der vorliegenden Erfindung mit unterschiedlicher Position der Scheibenmesser in Bezug auf die Nutmesser.

Figur 4 einen Querschnitt durch eine andere Ausführung eines Nutmessers

Figur 5 einen Querschnitt durch eine Schneidevorrichtung gemäß Figur 2 mit geänderter Anordnung der Kreismesserwelle.

The object was achieved according to the invention with a cutting method with the features mentioned in the claim. Further details of the invention emerge from the drawings. The invention will now be explained in more detail with reference to the drawings, omitting the parts which do not directly concern the invention. Show it

1 shows a cross section through a cutting device according to the prior art

Figures 2 and 3 cross sections through a cutting device for performing the method according to the present invention with different position of the disc knife with respect to the grooving knife.

Figure 4 shows a cross section through another embodiment of a slot knife

Figure 5 shows a cross section through a cutting device according to Figure 2 with a modified arrangement of the circular knife shaft.

A multiple cutting tool is shown schematically in FIG shown how to make it narrow ribbons made from a wide sheet of film is used. The disc knife (1) and the grooving knife (3) are here at equal intervals on the Knife shafts (6) or (7) arranged, The disc knives (1) plunge with their circumference a groove (5) in the groove knives, each through the opposing surfaces of the Cutting school formed by two slot knives. The grooving knives (3) are rigid with the knife shaft (6) connected. In contrast, the disc knives (1) on the upper knife shaft (7) and are stored by the disc springs (4) against the pitch reference surface the spacer rings (9) tensioned. The division distance the spacer rings (9) corresponds to that Pitch of the grooving knife. Of course can the disc springs (4) by other spring means be replaced.

The immersion depth of the disc knife in the Cutting shoulder (10, 11) of the grooving knife is 0.1 to 1 mm, preferably 0.3 to 0.5 mm. The disc knife can have a rectangular cross section and have a thickness of about 0.5 mm. Likewise are other disc knife shapes possible, for example Slicing knife with a bevel on the of facing away from the cutting shoulder of the slot knife Side of the disc knife is attached. The disc knife is made of hard metal, for example under the trade name Widia hard metal known from the Krupp company. The grooving knife (3) are also made of hard metal. Have the grooving knife in the area of contact with the disc knife rectangular cross section and the thickness of the spacer rings between two slot knives (8) measures itself according to the width of the cut Tapes. For example, to separate in is 3.81 mm wide magnetic tapes the thickness of the grooving knife and the spacer rings each about 2 mm. In the preparation of the grooving knife (3) becomes both cutting shoulders (10, 11) the grooving knife to a roughness depth of Rt <0.2 µm, preferably 0.1 µm, ground. The cylindrical The outer surface of the grooving knife is used by everyone Regrinding the grooving knife also to a roughness depth ground from Rt <0.2 µm, two sharp Cutting edges (13, 14) are created on each grooving knife. After assembling the above Knife shafts (6, 7) lie according to FIG. 2 each Disc knife on the right cutting shoulder (11) of the grooving knife (3). When cutting both knife shafts rotate in opposite directions. If now due to wear the right cutting shoulder the cutting quality has become insufficient, it will still be intact left cutting shoulder (10) the grooving knife used, as shown in Figure 3. For example by removing and turning the complete Disc knife shaft (7) happen. However, this is only makes sense if the disc knives wear (1) is still low. Otherwise one is new ground disc knives equipped disc knife shaft in the manner shown in Figure 3 with the hitherto unworn cutting shoulder (10) to bring the grooving knife into contact. After that you can be cut further until the left cutting school (10) unusable due to wear became. Only then will the grooved knife shaft removed, and the cylindrical jacket surfaces (12) the grooving knife is ground down until at every grooving knife has sharp cutting edges on both sides are present, the double use described enable the grooved knife shaft.

• Beim Schieifvorgang entstehen bei den Nutmessem gemäß dem erfindungsgemäßen Schneideverfahren gleichzeitig zwei scharfe Kanten, die nacheinander einsetzbar sind. Dadurch liegen bezogen auf die Nutzungsdauer der Messer geringere Schneidkosten vor, was für eine rationelle Fabrikation wichtig ist
• die Breite der Abstandsringe (8) legt die für die Schnittgüte des zu schneidenden Materials relevante Spaltbreite (5) der Nutmesser fest Diese Spaltbreite bleibt während der gesamten Gebrauchsdauer der erfindungsgemäßen Schneidvorrichtung konstant
• durch den konstanten Andruck der Scheibenmesser durch Tellerfedern an die Nutmesser entsteht über die gesamte Folienbahnbreite eine konstante Schnittgüte der geschnittenen Bänder.

The cutting method according to the invention has the following advantages over the known cutting processes:

• During the grinding process, two sharp edges, which can be used one after the other, arise simultaneously in the groove knives according to the cutting method according to the invention. As a result, there are lower cutting costs in relation to the service life of the knives, which is important for efficient production
• the width of the spacer rings (8) defines the gap width (5) of the grooving knife relevant for the cutting quality of the material to be cut. This gap width remains constant during the entire service life of the cutting device according to the invention
• Due to the constant pressure of the disc knives by disc springs on the slot knives, the cut strips are cut across the entire width of the film web.

The grooving knife can be the one shown in FIG Have shape, in which case no spacer rings are required, rather determines the route (h) the gap width. The difference between that shown in Figure 4 Grooving knife shape compared to known Similar slot knives is that here two Side surfaces (10 ', 11') with high surface quality are present, which means regrinding two sharp cutting edges of the grooving knife are created, what the double use of the slot knife shaft enables.

Usually the sum of the grooving knives is Spacer ring width the width of the cut Determine the tape strip. However, too integer multiples of this strip width as Cutting width come out when the disc knife shaft is equipped accordingly.

Figure 5 shows an example of this, the here Width of two segments of the slot knife shaft corresponds. In this case, everyone to be cut lies Strip on two lateral surfaces of the grooving knife. In the example shown in Figure 5, the slot knife shaft used four times for each regrind be within the distance of the Bandwidth four cutting schools of the slot knife shaft can be used.

Claims (1)

1. A method whereby foil webs comprising abrasive layers, more particularly magnetic tapes, can be cut by a number of disc blades (1) rotatably mounted on a shaft (7) and a corresponding number of cylindrical slot blades (3) mounted on a shaft (6), said slot blades having a rectangular cross-section in the area of contact with said disc blades (1), wherein

   the disc blades are pressed by cup springs (4) against the cutting shoulders (10,11) of the slot blades,

   the two cutting shoulders (10,11) and the cylindrical lateral surface (12) of the slot blades (3) which are made of hard metal are ground to a surface roughness of less than 0.2 µm,

   the disc blades which are made of hard metal are first disposed against one cutting shoulder of the slot blades (3),

   after the cutting edge (13,14) of said cutting shoulders becomes worn, the disc blades (1) are placed against the other cutting shoulder of the slot blades (3) without prior modification of the slot blades (3) mounted on the shaft (6),

   and wherein after both cutting edges (13,14) become worn, the slot blades (3) are repaired by re-grinding their cylindrical lateral surface (12) to a surface roughness of less than 0.2 µm.

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