DE1427251C3 - Flying trimmer for sheet metal, especially heavy sheet metal - Google Patents

Description

The invention relates to flying shears for trimming sheet metal, in particular heavy sheet metal a first knife carrier with an upper knife, which has a convex curved cutting edge with a circular knife-like has a large radius of curvature and when cutting with one carried by a second knife carrier Lower knife cooperates.

A "bow knife scissors" described in US-PS 19 86 685 It is also suitable for cutting to length and thus also for trimming in the same way for Querais of sheets in rest position.

Especially when using such arch knife scissors for trimming sheet metal, Demand to accelerate meter-long heavy metal sheets for a short time between the trimming cuts and again to slow down, high demands on the drive of feed means. These requirements must but must be met in the interests of high throughput.

These difficulties related to the discontinuous sheet feed do not exist Circular knife scissor lines, as these work with a continuous sheet feed. Meanwhile the rises Diameter of the circular knife with the maximum sheet thickness to be cut strongly, so that in the area of thick heavy plates the long-knife trimmer is predominant.

This is due to the fact that such large circular knife diameters could hardly be designed in a meaningful way as they would be necessary to achieve a favorable cutting angle with thick heavy plates.

In a reference from which the generic term was formed (Kalt-WaIz-WeIt, Halle-Saale, No. 2, February 1941), it is stated in connection with cold-rolled strips that the strips are made with the aid of »flying Hemming shears «can be cut. Since there are also flying saws for cutting through what is in motion If there is rod material that migrates with the material to be cut when it is cut, this reference can do it suggest to let a trimmer of the type for the flying cut wander with it, although under With a »flying hemming shears for cold strip«, the expert initially only imagined a circular knife hemming shear has, especially since stationary shears with rotating knives are also referred to as flying shears, if they are only designed to cut material to be cut while in motion (US-PS 27 01 016).

With regard to the above-mentioned reference from 1941, the invention is based on the fiction of a flying trimming shear of the genus, ie trimming shears of the type that temporarily move with the sheet metal. It was recognized, however, that with this flying arrangement of trimming shears, time is of the essence, because during the time of the return stroke of the cutting upper knife and the return of the scissors to the starting position, the sheet metal is pushed forward so that the knife does not close there during the subsequent cut cut can start where you left off with the previous cut. One would have to let the scissors run very quickly in order to allow the instant separation point, that is, the point on the sheet metal that runs as a separation point from one end of the knife to the other, to move towards the sheet feed so quickly that with consideration for the Sheet feed there is enough time to return the upper knife and the scissors to their starting position.
The invention is therefore based on the object of accelerating the movement of the sheet metal separating point against the sheet feed direction in a flying trimmer with long knives without having to increase the speed of the working stroke of the upper knife.

According to the invention, this object is achieved in that the trimming shears temporarily move along with the sheet metal is movable and that the upper knife with swaying cutting movement against the feed direction of the sheet metal with a cutting angle that decreases during the cut and both top and lower blades can also be driven in a translatory and reversible manner.

The effect of the measure thus claimed is that the instant separation point in the

Space moves towards the sheet feed without affecting the cutting speed of the knives, i.e. the The cutting frequency must be set sufficiently high in comparison to the feed speed of the sheet

would have to keep the knives for the next cut as the sheet feeds return to the starting position.

The realization of the teaching, the upper knife with the cutting angle decreasing during the cut To drive, the skilled person is no problem, since this feature is in the well-known Rock cut scissors with straight knives, for example according to DT-PS 8 61 950, due to the rock cut incidentally adjusts. Since such scissors are only intended for cutting a stationary sheet, it plays there is no accelerated movement of the sheet metal separation point due to the decreasing cutting angle Role.

In the case of the flying trimmer according to the invention, there are both the upper and lower knife carriers driven along guide tracks, of which at least the guide track for the upper knife carrier opposite to the cutting edge of the upper knife runs in the same direction circularly curved, the decrease of the cutting angle due to a different position of the centers of curvature of the guideway and the curved cutting edge is set, and wherein further a blade part guiding the upper blade can be moved upwards to reset the upper knife after the cut has been completed.

To realize the different position of the centers of curvature and thus the cutting angle To reduce the knife according to the invention during the cut, there are several possibilities. One possibility is that the center of curvature of the circular guide path of the The upper knife is located in front of the center of curvature of the cutting edge in the feed direction of the sheet is. If the centers of curvature of both knife carrier tracks for reasons of a simplified Drive should be kept in a vertical plane, another option is preferred after which is the center of curvature of the circular guide path of the upper knife in a smaller perpendicular The distance from the sheet metal is the center of curvature of the knife cutting edge.

With US-PS 20 12 849 is already a device for processing the edges of metal sheets with convex shaped tools, which are moved by means of guides on curved paths, became known, but not with flying shears for continuous trimming.

In the drawing, two exemplary embodiments of flying trimming shears according to the invention are shown, namely show

F i g. 1 to 3 the basic structure of the scissors and their drive without the measure according to the invention the constantly decreasing cutting angle,

F i g. 4 to 6 the preferred embodiment of a flying trimmer with representation of the means for setting a cutting angle that is constantly decreasing during the cut and

F i g. 7 shows a section through an upper knife according to FIG Line VII-VII in FIG. 2 in an enlarged view.

Starting from FIG. 1 to 3, a trimmer consists of an upper part 1 and a lower part 2 of the scissors. Long knives 5 and 6 with convexly curved cutting edges and transverse knives 7 and 8 for cutting the seam strips to length are inserted into the knife carriers (FIG. 7). The cutting edges each have the same center of curvature 9 and 10 as the guideways la and 2a. However, the radii of curvature of the same parts above and below can be different and the center of curvature at the top can also lie in a different vertical plane than the center of curvature of the lower parts. In all cases - if the knives 5 and 6 are moved back and forth on their paths la and 2a at the same speed - the point 11 of closest approach of the cutting edges remains on the connecting line between the centers of curvature 9 and 10, in the case of FIG. 1 to 3 in the vertical center plane 12.
The knife carriers 3 and 4 have a type of internal toothing 13, 14 on their rear sides, into which a pinion 15 and 16, which is mounted in the upper part 1 and lower part 2, engages. The pinions are driven synchronously and reversibly in opposite directions by reduction gears or, more appropriately, by rotary piston drives. Such a thrust piston rotary drive is shown in FIG. 3 for rotating the lower pinion 16 and consists of a cylinder housing 24 which supports the bearing points for the pinion 16 and in which a piston 25 can be acted upon on both sides is guided. The piston carries a toothed rack 25a which meshes with the pinion 16. The cylinder housing 24 is carried by the lower part 2 of the scissors.

The upper scissor part 1 can be pivoted about the pin 17 by means of a crank mechanism 18, 19. Pin 17 and Cranks 18 are mounted in a rear wall 20 firmly connected to the lower part 2, via which the shear pressure is returned to the lower part 2.

F i g. 1 shows the starting position of the knives 5 and 6 or 7 and 8 with sheet metal 21 coming from the right.

If the drive of the pinions 15 and 16 is switched on in the indicated direction of rotation, the knives 5 and 6 lead cut a circular knife cut on its arched entrance to the left, as the knives are practically sectors of circular knives are extremely large in diameter and move around their centers of curvature. in the Point 11 remains the dividing point between the sheet metal and the seam strip in the room with the previous sheet metal, and finally, after the end of the process, the knives according to FIG. 2 the cross knives 7 and 8 in the vertical Central plane 12 are used and cut off the hem strip.

For these reasons, the sheet feed must stop while the knife retracts to the right. Since the upper transverse knife 7 lies in front of the cut sheet metal edge, the drive is to be revised the pinion 15 and 16 to adjust the crank 18 by 180 °, the upper part 1 according to FIG. 3 swings up. The knives then return to their starting position as shown in FIG. 1 back, with the top going down again and a new cut can be made.

The embodiment according to FIG. 4 to 6 has been further developed for continuous sheet feed by the kinematic conditions are such that the point of closest approach of the knives, d. H. the separation point that moves towards the sheet metal during the cut

This differs from the trimming shears according to FIG. 1 to 3 is initially the straight formation of the lower knife 6a, the knife carrier 4a and the associated guide track 2b. The toothing on the underside of the knife carrier thus becomes a rack toothing 14a. This simplification would also apply to the

14th

Scissors according to fig. 1 to 3 conceivable without having to worry about the unchangeable position of the separation point something changes.

What is essential for the changed kinematics is the feature that the center of curvature 9a of the upper cutter 5a is at a greater vertical distance from the sheet metal 21 than the center of curvature 23 of the associated trajectory \ b for the knife carrier 3a. The curved cutting edge of the upper knife 5a is therefore eccentric to the movement path 16 with the larger radius of curvature in the sense that the separation point 11a from the starting position according to FIG. 4 to the end position after the separation cut according to FIG. 5 moves towards the sheet 21 by the amount a. The upper knife 5a makes, as it were, a rocking cut with respect to the lower knife. Within the time that the sheet needs with uninterrupted feed for the dimension a, the knives can be pivoted upwards of the upper part 1 in the starting position according to FIG. 4 go back. If the speed of the knife retraction is made variable, e.g. B. increased, you can shorten the length of the separated hem strips.

According to FIG. 2, the cutting edges of the knives move away behind point 11 while cutting from each other, their "return stroke" takes place for the most part in the sheet metal in the cut. This is the upper knife 5 largely free of the cut sheet edge when pivoting the upper part 1.

This is different in the embodiment with shortened guide tracks \ b, where the upper knife 5a when pivoting the upper part 1 according to FIG. 6 would have to sweep past the trimmed sheet edge almost in full length and the sheet lying between two opposing trimming shears could be pulled up.

This is remedied by using a measure known from circular knife scissors, in that the guideways of the upper knife carrier 3a and lower knife carrier 4a and thus the cutting edges of both knives in the vertical projection form a small angle α, so that the upper knife 5a lifts off the cutting edge of the metal sheet in the horizontal direction behind the separating point 11a (Fig. 7). The inclination of the guideways to one another has the same purpose as the known inclination the center axis of the upper circular knife in normal circular knife scissors.

To adjust the knife gap, the upper knife carrier is in its guide or together with the Scissors upper part adjustable parallel to itself in a manner not shown.

1 sheet of drawings

Claims (4)

Patent claims: 1. Flying shears for continuous trimming of sheet metal, especially heavy plate, with a first knife carrier with an upper knife, which has a convexly curved cutting edge with a has a large radius of curvature similar to a circular knife and when cutting with one of a second Knife carrier supported lower knife cooperates, characterized in that the Trimming shears can temporarily be moved along with the sheet metal, and that the upper knife (5a) with a swaying cutting movement against the feed direction of the sheet metal web (21) with during the Cut decreasing cutting angle and both upper and lower knife translational and are reversibly drivable. 2. Trimming shears according to claim 1, characterized in that both the upper and the lower knife carrier (3a, 4a) along guide tracks (tb, 2b) can be driven, of which at least the guide track (ib) for the upper knife carrier (3a) compared to the The cutting edge of the upper knife (5a) is curved in the same direction, the cutting angle being reduced by a different position of the centers of curvature (23, 9a) of the guideway and the "curved cutting edge, and furthermore a scissors part (1) guiding the upper knife for resetting the Upper knife can be displaced upwards after the cut is finished. 3. Trimming shears according to claim 2, characterized in that the center of curvature (23) of the circular guide track (Ib) of the upper knife (5a) is upstream of the center of curvature (9a) of the cutting edge in the feed direction of the sheet (21). 4. Trimming shears according to claim 2, characterized in that the center of curvature (23) the circular guide track of the upper knife (5a) at a smaller vertical distance from the sheet metal (21) lies as the center of curvature (9a) of the knife cutting edge.