DE2257041C2 - Trimming shears on trimming shears for rolled sheets - Google Patents

Description

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The subject of the invention is a hem strip cutting shears on the outlet side of the opposite one Double trimming shears for rolled sheet, with the knives at right angles to the blades of the trimming shears are arranged and the lower cutter is stationary, while the upper cutter by a drive device can be moved up and down in a knife guide relative to the lower knife.

A problem with the known hem strip dividing scissors is that the upper knife in his following each cutting stroke, the return stroke with the knife face on the cutting edge that has just been created The edge strip that has already been cut by the trimming shears but is still hanging on the sheet slides along. It can happen that the edge strip is removed from the upper knife, which is returning to its starting position is taken and bent upwards. The cut edge of the hem strip is then in front of the Knife face of the upper knife in its upper end position. A feed of the sheet is then not more is possible.

Another disadvantage is to be seen in the fact that the known hemming strip dividing shears despite different Thickness of the rolled sheets with a constant cutting gap (distance of the knife face plane of the Lower knife from the knife face level of the upper knife). It is true that there is such a thing in the case of hem strips splitting shears that are effective as downright scrap shears, no need for flawless ones To ensure cut edges. But if the cutting gap is aligned to a medium sheet metal thickness, it can it can happen that the hem strip is not completely separated from thin metal sheets. With thick ones Sheet metal, the cutting gap that is too small has an adverse effect on the service life of the knives of the trimming scissors the end.

The invention is based on the object of providing a hemming strip cutting scissors on trimming scissors of the above-mentioned to design mentioned genus so that during the return stroke of the upper knife a bending of the not yet edge strip separated from the sheet is avoided and thus an unhindered sheet feed after the Trimming cut is ensured.

To solve this problem it is proposed that the knife guide of the hem strip cutting scissors around an axis running parallel to the knife edges, but transversely to the stroke direction, is pivotably suspended and can be displaced by an actuator which has an eccentric engaging the knife guide has the by a self-locking gear, z. B. a worm drive, is continuously rotatable

Although it is already known from DE-GM 18 60 887 the guides for the upper trimming knife double trimming shears positioned opposite each other after each trimming cut by means of an eccentric to avoid friction between the knife and the cutting surface. As is well known, friction leads to wear of the trimming knives and thus to an impairment of the cutting edge quality of the trimmed sheets. This well-known scissors of another genus, however, has the development of Can not influence hem strip dividing scissors in the direction of the solution according to the invention. Of the The reason is probably primarily to be found in the fact that it is about the solution of different problems It can but it can also be attributed to the fact that hem strip dividing shears are on the outlet side of double trimming shears are arranged in such a way that the dividing scissors upper knife is close to the one that has already been trimmed Sheet edge are moved past. It became apparent when there was a non-rigid guide for the cutting shear upper knife feared damage to the trimmed sheet edge.

In the drawing, a hem strip cutting scissors according to the invention is shown in a purely schematic view shown in association with a shear unit of a double trimming shear for rolled sheets.

In the scissors stand 1 is the fixed lower knife 2 of the trimming scissors and the perpendicular to it, Fixed lower knife 3 of the hem strip dividing scissors arranged. The movable upper knife 4 of the trimming shear is driven by two synchronously running crankshafts 5 and 6 via connecting rods 7 and 8 in such a way that it separates the seam strip from the rolled sheet in a so-called roll cutting movement against the lower cutter 2.

The separated hem strip is then determined into sections by the hem strip dividing scissors Lengths cut by the upper knife 9 by a crankshaft 10 via a connecting rod 11 in the working stroke is guided downwards against the lower knife 3. The knife carrier 12 for the upper knife 9 of the Edging strip cutting scissors is movable in a knife guide 13 arranged in the scissors stand 1, which near its upper end about an axis 14 directed parallel to the cutting edge of the knives 3 and 9 is pivotable.

For pivoting the knife guide 13 is a mounted in the scissors frame 1 eccentric 15, which of a self-locking actuator, for example a worm drive 16, is rotatable. Of the Worm drive 16 is moved by a servomotor 17. By rotating the eccentric 15, the Knife guide 13 for the knife carrier 12 are pivoted about the axis 14 so that the cutting gap between the stationary lower cutter 3 and the movable upper cutter 9 of the hemming strip cutting shears is changed. It is thus possible in a simple manner, the cutting gap between the knives 3 and 9 according to the respective sheet thickness. In addition, the servomotor 17 can be switched so that that he after each cutting stroke of the upper knife 9 and before the start of its return stroke on the eccentric 15 the

Knife guide 13 also swivels so far away from the lower knife 3 that the upper knife 9 is in contact the cut edge of the remaining hem strip is raised. Before the start of the next cutting stroke the servomotor 17 resets the knife guide 13 to that corresponding to the sheet thickness Default value

1 sheet of drawings

Claims (1)

Claim: Hem strip cutting shears on the outlet side of double trimming shears positioned opposite for rolled sheets in which the knives are arranged transversely to the knives of the trimming shears and that The lower knife is stationary, while the upper knife is driven by a drive device in a knife guide is movable up and down with respect to the lower blade, characterized in that the knife guide (13) of the hemming strip cutting scissors around one parallel to the knife edges (3, 9), but the axis (14) running transversely to the stroke direction is pivotably suspended and operated by an actuator (15, 16, 17) is displaceable, the one on the knife guide (13) engaging eccentric (15) has, which is through a self-locking gear, z. B. a worm gear (16), continuously rotatable is 10