GB2148160A

GB2148160A - Braking stand in strip metal coiling process

Info

Publication number: GB2148160A
Application number: GB08422464A
Authority: GB
Inventors: Konrad Febl; Gerhard Breitschopf
Original assignee: Voestalpine AG
Current assignee: Voestalpine AG
Priority date: 1983-10-12
Filing date: 1984-09-05
Publication date: 1985-05-30
Also published as: AT377930B; IT8412610A0; DE3427580A1; ATA363183A; GB8422464D0; IT1180828B

Abstract

The braking stand for braking slit metal strip comprises two pairs of braking rollers (4). In order to prevent a wandering of the strips, at least one bending roller (4a), which is adjustable in height, is provided between the two pairs of braking rollers (4). <IMAGE>

Description

SPECIFICATION Braking stand for braking slit metal strip This invention relates to a braking stand for braking slit metel strip, comprising two pairs of braking rollers.

In plants for slitting strip, braking stands are used to exert on each of the partial strips a predetermined braking force, which is selected in dependence on the material, so that stable coils will be obtained. In order to avoid surface defects resulting from the exertion of the required rearward pulling force on the strip, the braking rolls are driven with a minimum slip by the strip to be coiled.

A disadvantage involved in the use of such braking rollers arranged in pairs resides in that the line contact between the braking roller may cause the partial strips to wander so that a coiling edges and without damage to the edges cannot be ensured.

For this reason the braking rollers are often preceded by strip-pressing means by which a forward pulling force is exerted on the strip in order to prevent a wandering of the strip.

In an attempt to avoid a wandering of the partial strips without need for strip-pressing means, it has been proposed to provide braking stands with two pairs of braking rollers having axes which extend at an angle to each other. But in such braking stands the angle between the axes of the braking rollers must be selected in dependence on the wandering of the strip and it is possible to influence only the course of all partial strips rather than the course of individual partial strips.

For this reason it is an object of the invention to avoid said disadvantages and so to improve a braking stand of the kind described first hereinbefore that a wandering of the partial strips can be effectively prevented with simple means and in such a manner that surface defects will be avoided.

This object is accomplished in accordance with the invention in that at least one bending roller which is adjustable in height is provided between the two pairs of braking rollers.

The invention is based on the recognition that relatively small guiding forces will be sufficient to guide along a straight line of partial strip which tends to wander, provided that the partial strip is bent out of its plane of travel because in such case the path length difference between the inner and outer arcs can be compensated by a correspondingly stronger curvature of the partial strip at its outer arc and there will be no need to elongate the partial strip at its inner arc. For this reason it is sufficient to subject the partial strips to a tensile force, which when the partial strips are bent out of their path of travel will ensure a straight course of the longitudinal edge adjacent to the inner arc which could otherwise be formed in the plane of travel.

This can readily be achieved between the two pairs of braking rolls. For this reason there is no need for exerting a special forward pulling force for guiding each partial strip along a straight line so that the need for strip-pressing means is eliminated and an occurrence of surface defects is precluded.

A particularly simple design will be obtained if the bending roller is mounted on a pivoted rocker because the pivotal movement of the rocker permits an adjustment of the elevation of the bending roller relative to the pairs of braking rollers without a need for a vertical displacement of the bearings for the bending roller.

If the braking force is distributed to a plurality of pairs of braking rollers, it will be possible to exert by said braking rollers a more uniform tensile force on the strip because changes of the friction conditions adjacent to one pair of braking rollers can exert only a proportional influence on the total tensile force to ensure that the advantage can be afforded in spite of the provision of a bending roller, a further feature of the invention resides in that the bending roller constitutes one braking roller of an additional pair of bending rollers.

Whereas a stronger bending of a partial strip at its outer arc is restricted adjacent to that additional pair of bending rollers, a wandering of the partial strips can be prevented in most cases because the stronger bending at the outer arc, which stronger bending is required for a guidance along a straight line, is restricted, but is not prevented.

It will be understood that the additional pair of braking rollers, which constitute bending means within the braking stand, must be so arranged that they can be adjusted in height so that the desired curvature of the strip can be adjusted. For this purpose the two bending rollers of said pair may be mounted to be individually adjustable. A simpler design will be obtained if the additional pair of braking rollers, which comprises a braking roller that constitutes a bending roller, are mounted in a frame that is adjustable in height. In that case only that frame needs to be adjusted in height. To permit an adjustment of the braking rollers into engagement with the strip, at least one braking roller must be adjustably mounted in the frame.

The invention is illustrated by way of example in the drawing, in which Figure 1 is a simplified side elevation showing a braking stand in accordance with the invention for braking a slit metal strip, Figure 2 is a sectional view taken on line Il-Il in Figure 1 and Figure 3 is an end elevation showing that braking stand connected to means for effecting a regenerative braking.

The braking stand which is shown comprises a mainframe 1, which carries three frames 2 and 3 for respective pairs of braking rollers 4. The two outer frames 2 are immovably mounted on the frame 1. The intermediate frame 3 is disposed between the immovable frames 2 and is mounted so as to be adjustable in height. For this purpose the side cheeks 2a of the frames 2 may be provided with lateral guiding members, which extend into mating guiding grooves formed in the side cheeks 3a of the frame 3. This is not shown for the sake of clearness. The adjustment is limited by pins 5, which extend through the side cheeks 3a of the intermediate frame 3 and coopers! with stops 6 that are fixed to the mainframe. The adjustment in height is effected by means of two pneumatic bellows 7, although it will be understood that they may be replaced by other actuators, such actuating cylinders.

To permit an adjustment of the braking rollers 4 into engagement with the strip, the lower braking roller of each pair thereof is mounted in a rocker 8, the pivotal axis of which is defined by one of the rods 9 connecting the side cheeks 2a or 3a. Actuating cylinders 10 are pivoted to one of the connecting beams 11 of the frames 2 and 3, respectively, and are operable to impart a pivotal movement to the rockers 8 so that the braking rollers are adjusted into engagement with the strip 12, which is indicated by a dash-dot line in Figure 1 and has been slit into partial strips.

Because the lower braking roller 4 of the intermediate frame 3, which is adapted to be raised and lowered, acts as a bending roller 4a for bending the partial strips of the metal strip 12, the partial strips are bent out of their plane of travel between the braking rollers 4 mounted in the outer frames 2. Those longitudinal edge portions which are disposed in the plane of travel adjacent to a possibly existing outer arc can be bent more strongly so that the bending roller 4a will provide for a compensation of path length differences between inner and outer arcs without a need for an exertion of a separate force. In this manner it is ensured that the partial strips will travel along a straight line and a wandering of the partial strips adjacent to the braking frame can be precluded without a need for strip-braking means for exerting a corresponding forward pulling force.As a result, damage to the surfaces of the strip being handled will be precluded. The extent to which the strip 12 is bent out of its plane of travel through the braking stand can be selected in dependence on different tendencies of different strips to wander. As a result, the braking stand is highly versatile in use.

Whereas the braking rollers of each pair 4 can be mechanically braked, it will be more advantageous to provide a device 13 for regenerative braking so that the braking energy can be utilized. For this purpose the braking rollers of each pair 4 may be connected by universal-joint shafts 14 to a common transmission 15, which may be used to drive a controllable electric generator 16. In order to minimize the slip between the pairs of braking rollers 4 and the slit strip 12, a separate braking generator might be provided for each pair of rollers although such arrangement will involve a higher expenditure.

Claims

1. A braking stand for braking slit metal strip, comprising two pairs of braking rollers, characterized in that at least one bending roller which is adjustable in height is provided between the two pairs of braking rollers.

2. A braking stand according to claim 1, characterized in that the bending roller is mounted on a pivoted rocker.

3. A braking stand according to claim 1 or 2, characterized in that the bending roller constitutes one of the braking rollers of an additional pair of braking rollers.

4. A braking stand according to claim 3, characterized in that the additional pair of braking rollers comprising a braking roller which constitutes the bending roller are mounted in a frame that is adjustable in height.

5. A braking stand for braking slit metal strip, substantially as described hereinbefore and shown on the accompanying drawing.