DE1018300B - Plate-shaped circular knife for cutting strips of paper, cardboard, plastic, fabric or the like. - Google Patents

Description

GERMAN

Circular knives for cutting webs of paper, cardboard, plastic, fabric or the like often from a deformed by embossing, pressing or a similar machining process and then hardened sheet metal disc. It is always difficult in the manufacture of such circular knives that To avoid warping of the disc after the hardening process and the stresses that occur here to render ineffective. The elimination of such difficulties is already in various ways been tried.

The invention is based on the same object, in particular through the design of the knife is resolved. This consists in the fact that the outer edge of the disc is angled relative to the inner part and only the narrow annular edge part lying outside the crank is hardened, the however, the middle part lying within it is unhardened. The hardening of the edge part takes place expediently by means of the induction hardening process. This leaves the inner part of the knife unaffected by hardening and therefore cannot warp. Since he is outwardly about the narrow ring-shaped cranking merges directly into the flat or slightly conical edge part, it counteracts any hardness stresses of the same, with the cranking in particular as stiffening is effective.

If flat blank material is used for the production of the knives, then there is the advantage of that a processing of the knife is only required at the edge, while the other surfaces after the punching out of the holes can remain unprocessed, because they are not due to the hardening process attacked or contaminated. However, if processing is desired, it can be made up of the same Reasons can be made before hardening.

The offset caused by the offset of the edge part compared to the inner part offers also advantages when grinding. Even when sanding for the first time, you only need the on one side narrow ring surface of the edge to be processed and also the even narrower back part while all other surfaces can remain unprocessed. There is even less grinding work involved in regrinding required because machining can be limited to only one of these surfaces. As a result of the offset between the edge part and the rest of the knife is the transition from the sharpened to the unground knife Part of the disc sharply delimited and has a good one even after repeated regrinding Appearance. These and a few other advantages work together to the effect that the manufacture of the knife is significantly cheaper and simplified.

Plate-shaped circular knife

for cutting strips of paper,

Cardboard, plastic, fabric or the like.

Applicant:

Maschinenfabrik Goebel GmbH,
Darmstadt, Goebelstr. 21

Dr. Dr.-Ing. Wilhelm Köhler, Darmstadt,
has been named as the inventor

An embodiment of the inventive concept is shown schematically in cross section in the drawing.

The inner part α of the knife is provided with a bore b . It merges outwards into the annular part c , which is angled or angled opposite it. This continues to the outside in the edge part d . This annular edge part can either also lie in a plane like the inner part, or its surface can be very slightly conical, the angle α being only a few degrees.

To produce the knife edge, only the front surface e of the ring d and the knife back / need to be ground. For regrinding, it is sufficient if one of these surfaces is ground. Since the surface of the edge is very small compared to the rest of the knife, only relatively small areas need to be ground. If the new knives are to be interchangeable with the knives customary up to now without having to change the parts interacting with the knives, then the mutual position of the bore and the cutting edge must be adapted. This is done in such a way that the leg of the angle α, which is denoted by g, which is placed on the edge surface e , intersects the front surface of the inner part α approximately at the front edge h of the bore b.

Claims (3)

PATENT CLAIMS: 1. Disc-shaped circular knife for cutting strips of paper, cardboard, plastic, fabric od. The like. Consisting of one by embossing, pressing or a similar machining process 709 757/187 Deformed and then hardened sheet metal disc, characterized in that the outer edge of the disc is bent over from the inner part and only the narrow annular edge part (d) lying outside the bend (c) is hardened, while the middle part (α) inside it is unhardened . 2. Circular knife according to claim 1, characterized in that the flat or slightly tapered edge part (d) of the knife over the narrow and annular, acting as a stiffening crank (c) directly in the preferably flat inner, the bore (b) for placement the hub containing part (α) passes. 3. Circular knife according to claim 2, characterized in that the edge part (d) is conically shaped at such an angle (α) that each applied to this surface, the axis of rotation of the knife intersecting straight line (g) the front surface of the inner part (α ) cuts at the front edge Qi) of the hole (b). Considered publications:
German patent specification No. 464 835. 1 sheet of drawings © 709757/187 10.57