GB2143852A

GB2143852A - Treatment of metal strip

Info

Publication number: GB2143852A
Application number: GB08418829A
Authority: GB
Inventors: Manfred Grube; Guido Sandeck; Urick Raschat; Friedrich Delwig
Original assignee: Mannesmann AG
Current assignee: Vodafone GmbH
Priority date: 1983-07-28
Filing date: 1984-07-24
Publication date: 1985-02-20
Also published as: FR2549858A1; GB8418829D0; GB2143852B; DE3327172A1; IT1174613B; IT8422110A0

Abstract

A pickling line may be used for intermittent operation by using a transition plate 11 to cover a pit 14 used to receive a loop during continuous operation. The plate is arranged to descend into the pit during continuous operation thereby to form the loop when necessary. <IMAGE>

Description

SPECIFICATION Treatment of Metal Strip Lengths of metal strip may be treated, particularly pickled, by feeding the lengths along a line including a treatment section. Operation may take place intermittently or continuously. Intermittent operation is carried out by passing the lengths individually along the treatment line, whereas the line may be made to run continuously by joining the leading end of a fresh length of strip to the trailing end of that which has almost passed through the treatment section. To permit the strip inside the treatment section to continue its movement while the ends are being joined together, a loop may be formed at the entrance to the treatment section during normal running, conveniently in a pit formed in the floor of the plant. The slack in the loop provides a supply of strip while two lengths are being joined together, often by welding.To achieve the foregoing, it is necessary to provide driving pulleys capable of varying the speed of the strip.

However, continuous operation has hitherto been impossible if the strip is composed of material which is unsuited to welding (high carbon or high alloy steels) or if the strip is too thick (above about 10 mm) to form loops, or if there are great differences of thickness in successive lengths of strip. In all these cases, intermittent operation is necessary. A continuous pickling line is also known (see Stahl- und Eisen 1972, page 1210), in which successive strips composed of unweldable material are joined together without recourse to welding, by means of a stamping operation. However, since the loop pit is designed to receive multiple loops and repeated flexing takes place.Owing to the unequal flexural strength of successive strips which are fixed to each other, a kink is formed in the region of the joint during loop formation, causing a joint formed by stamping to become detached particularly easily.

The same risk of a joint becoming detached also rises if a loop is formed downstream of the treatment section either to permit shearing or if the leading end of the strip has to be clamped in a coiler rotating initially at a peripheral speed less than the speed of the strip.

We have appreciated that, to reduce the risk of separation at a joint, in particular if there is a large difference in the thickness of successive strips, a simple sagging loop is desirably formed in a pit between the jointing machine and the treatment section to provide the necessary slack to permit the jointing operation, but the loop is picked up after jointing by speed adjustment of the advance means so that the joint runs over the pit without significant distortion.

To facilitate operation, a transition plate is provided which covers the pit but which can be disenabled in such a way that it does not obstruct loop formation. To this end, the transition plate is lowered into the pit during loop formation.

The transition plate can be raised as the loop is picked up to bring it into the transition position when the strip is advanced further once the fixing process is completed, and the plate may occupy this upper position during intermittent operation.

The transition plate may be associated with a deflecting roller and be lowered into the pit together therewith. This deflecting roller enables even relatively thick strips to be formed into a loop so that a changeover can be made from discontinuous intermittent operation to continuous operation even with thick strips.

Whatever position the deflecting roller adopts, the transition plate lies beneath the strip, does not obstruct loop formation and is immediately available when the loop is picked up. The deflecting roller also helps to prevent the formation of kinks in the strip during loop formation. The deflecting roller can also be used by operating a sensor to indicate the effective depth of the pit and for coordinating the acceleration and the speed of the strip when picking up the loop as the deflecting roller is raised.

Loop formation by allowing the strip to sag is possible because the jointing proceeds rapidly by stamping. The short length of the pit becomes advantageous when the free sag length between the jointing machine and a driving apparatus normally arranged upstream of the treatment section is short and any bending of the strip is only slight and does not endanger the joint.

Since this method not only makes it possible to fix together strips having great differences in thickness but is also free from the risk of the joints becoming detached, it opens up the possibility of providing a pickling line capable of accommodating extreme requirements permitting possible differences in thickness for strips thicker than 5 mm having the necessary inherent strength to withstand intermittent operation and allow the treatment of strips of otherwise unsuitable composition.

A pickling line as proposed herein can operate intermittently or continuously using a fixing machine and sag pits upstream and downstream of the treatment section. With a strip pickling line of this type, it is possible to process a range of strip thicknesses from about 1.5 to 1 5 mm, irrespective of the composition (weldable or not).

A particular advantage lies in the fact that, when transferring to thin strip which cannot be treated intermittently owing to its inadequate strength and the associated risk of bulging, the leading end of the strip can simply be joined to the preceding strip and can be pulled through the line, whereupon the thin strip is clamped into the freed coiler or a second coiler. Two take-off coilers are preferably also provided on the entry side.

The drawing is a diagrammatic view of a pickling line. During continuous operation, strip to be processed is supplied in coils to two uncoilers 1 and 2, strip being fed from one through the line while the other is being made ready. The take-off coiler 1 is also used for thicker strips which are passed straight through the line when it is used for intermittent operation. Downstream of the uncoilers are driving roll blocks 3 and 4 and straightening roll sets 5 and 6. Cropping shears 7 with two independently actuable pairs of blades serve to crop the upstream and downstream ends of strip.

The cropping shears 7 are followed by a machine 8 of known design for joining the leading end of a length of strip fed from one uncoilerto the trailing end of a length leaving the other, the machine operating by stamping. During intermittent operation, the strip 9 passes from the uncoiler 1 through the components described above and is further advanced by a driving roll block 10 over a transition plate 11 into the treatment section 12 which is preceded by a further driving roll block 13. The plate 11 covers a pit 14 into which the strip is allowed when necessary to sag and form a loop when the line is used for continuous operation. Deflecting rollers 1 5 are provided at the entry end and exit end for kink-free loop formation.

Arranged one at each side of the pit 14 are two vertical guides 17 for sliding blocks (not shown) supporting an assembly including the shaft of a deflecting roller and the transition plate 11 which is located slightly below the deflecting roller. The deflecting roller 1 8 and the transition plate 11 are movable together into the pit 14.

The drawing shows firstly the deflecting roller 18 and the transition plate 11 in a position in which a thick strip 9 passes through the plant in a straight line by intermittent operation, being preferably deflected only slighly by the deflecting roller 1 8. By setting the transition plate in a somewhat higher position, the transition plate 11 serves to introduce the leading end of a strip reliably into the treatment section 1 2 while bridging over the pit 14, in either intermittent or in continuous operation. In the event that continuous operation is required, when the end of a length of a strip is about to leave one uncoiler and a jointing operation becomes necessary, loop formation is achieved by lowering the assembly including the transition plate and deflection roller 1 8. Following the joining operation, the loop is picked up.

The drawing shows the deflecting roller with maximum loop formation in the lower position 18' shown in dot-dash lines and also the transition plate 11 in position 11 ' from which the transition plate can be driven back up into the solidly drawn upper working position after loop is picked up.

Claims

1. A strip treatment line having a pit into which the strip may sag in order to form a loop, and a transition plate movable from a position in which it bridges over the pit into a position within the pit to permit loop formation.

2. A line according to claim 1, wherein the transition plate is associated with a deflecting roller and can be lowered therewith into the pit.

3. A line substantially as hereinbefore described with reference to and as illustrated in the drawing.