RU2292257C1 - Cutter for cutting out holes in elastic sheet material - Google Patents

Abstract

FIELD: plastic working of metals.

SUBSTANCE: cutter is in the form of pipe. Pointed cutting edge is formed on pipe. Several teeth having pointed apexes and lateral cutting edges are alternatively arranged along length on pipe with mutual overlapping along circle in their widest portion. Each tooth has two cutouts near its root; length of said cutout in direction of cutting motion exceeds thickness of cut-out material.

EFFECT: lowered effort used for cutting out holes in elastic sheet material.

4 cl, 5 dwg

Description

The invention relates to tools for punching holes in elastic sheet material.

Known punch, consisting of a pipe with a pointed front cutting edge (Russian patent MKI B 26 F 1/44, No. 2223085, published 12.27.04, Bulletin No. 36). When using such a punch, the cutting edge simultaneously presses along the entire length of the material being cut. In this regard, there is a large cutting force.

The closest to the purpose is a knife for cutting holes in an elastic material having a sharp cutting edge, known from ed. SU 743893 A, B 29 H 3/06, 06/30/1980.

At the same time, a knife that is close in technical essence is a knife consisting of a pipe with a pointed front cutting edge and a pointed tooth with side edges, while the tooth has a one-sided cutout at the base (Russian patent No. 2069148, MKI B 26 F 1/44, published November 20, 1996 g., bulletin No. 32).

When such a knife cuts holes in an elastic sheet material, for example, when cutting sides from tires, the material first punctures the tip of the tooth, then the material is partially cut by the sharp lateral edges of the tooth and, due to its elasticity, is partially stretched on the tooth. When passing through the material of the base of the tooth, the material, due to its elasticity, flows into the cutout at the base of the tooth. Then on the remaining uncut tooth most of the material simultaneously presses along the entire length of the pipe cutting edge. In this regard, there is a large cutting force.

The present invention solves the problem of reducing the force when cutting holes in the elastic sheets of material.

To solve this problem, the knife for cutting holes in the elastic sheet material is made in the form of a pipe, a pointed cutting edge is located on the pipe, while on the pipe there are several pointed teeth made with lateral cutting edges, alternating through one along the length and overlapping each other around the circumference in the widest part, each tooth has two cuts at the base with a length in the direction of cutting movement greater than the thickness of the material being cut.

An option for solving the problem is that the teeth of the knife are removable. Another option for solving the problem is that the teeth of the knife are made with the possibility of adjustment along the length.

Another solution to the problem is that longitudinal recesses are made on the outside of the teeth.

The implementation of the claimed options is illustrated by the following drawings:

figure 1 depicts the appearance of a knife;

figure 2 is a view of the knife from the teeth;

figure 3 - appearance of a knife with removable teeth;

figure 4 - appearance of a knife with adjustable length teeth;

5 is a transverse section of a tooth with longitudinal recesses.

Figure 1 shows a knife, consisting of a pipe 1 with a front cutting edge 2 with alternating through one short 3 and long 4 pointed teeth. Each tooth 3 and 4 has two lateral cutting edges 5 and two cutouts 6 at the base. The length of each cutout 6 in the cutting direction is greater than the thickness of the material being cut. Teeth 3 and 4 are located with overlapping in its widest part of each other around the circumference. In Fig. 2, the overlap is indicated by the letter “a”, the optimal amount of overlap “a” depends on the elasticity and thickness of the material being cut, for example, when cutting sides from tires, the amount of overlap is approximately equal to the thickness of the material being cut.

Figure 3 shows an embodiment of a knife, the teeth 3 and 4 of which are removable. Each tooth 3 and 4 has two holes through which two screws 7 connect the tooth to the pipe 1.

Figure 3 shows an embodiment of a knife, the teeth 3 and 4 of which are made adjustable in length. Each tooth 3 and 4 has four holes 8 located at the same distance from each other, through which two screws 7 connect the tooth to the pipe 1.

Figure 4 shows a cross section of one of the teeth, on the outer side 9 of which there are longitudinal recesses 10.

When cutting the holes proposed by the knife with the elastic sheet material, the material is first pierced with the tips of long teeth 4. With further movement of the knife, the material is partially cut by the side cutting edges of 5 teeth 4, and part of the material, due to its elasticity, is stretched to them. Then, before the uncut part of the material begins to fold in the hollows between the long teeth 4, the material is pierced by the tips of the short teeth 3. With the further movement of the knife, the material is partially cut by the side cutting edges 5 of the teeth 3, and part of the material, due to its elasticity, stretched on them. Before the uncut part of the material begins to fold in the depressions between the teeth 3 and 4, the material, passing through the widest part of the long teeth 4, is straightened, first pulling the narrowed part of the long teeth 4, and then, passing the widest part of the short teeth 3, further straightens, tightening the narrowed part of the short teeth 3. With the further movement of the knife, the remaining uncut a small part of the material stretched on the narrowed parts of the teeth 3 and 4, cuts the front cutting edge 2 of the pipe 1.

Thus, when using the proposed knife, a reduction in cutting force is achieved when cutting holes in the elastic sheet material.

The presence of removable teeth reduces the cost of regrinding and knife repair.

Rearrangement of the teeth by the size of the step between the mounting holes forward or backward relative to the cutting edge allows you to optimize the cutting conditions for materials of varying thickness and elasticity by changing the length of the teeth.

The presence of longitudinal recesses on the outside of the teeth further reduces the cutting force by reducing friction on the teeth of the elastic material being cut.

Claims (4)

1. A knife for cutting holes in an elastic sheet material having a pointed cutting edge, characterized in that it is made in the form of a pipe, a pointed cutting edge is located on the pipe, with several pointed teeth made with side cutting edges alternating through one along the length and overlapping each other around the circumference in the widest part, each tooth has two cuts at the base with a length in the direction of cutting movement greater than the thickness of the material being cut. 2. The knife according to claim 1, characterized in that the teeth are removable. 3. The knife according to claim 1, characterized in that the teeth are made with the possibility of their adjustment in length. 4. The knife according to claim 1, characterized in that longitudinal recesses are made on the outside of the teeth.

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