Coiling machine for hot rolled stock such as strip or sheet

Winding – tensioning – or guiding – Convolute winding of material – With spool loading or coil removal

Reexamination Certificate

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Details

C242S615110, C242S615120

Reexamination Certificate

active

06332588

ABSTRACT:

FIELD OF THE INVENTION
This invention concerns a coiling machine for hot-rolled stock such as strip or sheet, as set forth in the main claim.
The invention is applied in rolling lines for flat products to optimise, rationalise and accelerate the steps of forming the hot rolled coils performed downstream of the rolling train.
The invention is applied specifically with regard to the production of strip or sheet both with a thickness of between 0.5 and 5 mm, and also of more than 5 mm, with the temperature of the rolled stock at about 700÷800° C. or more and with a production of around 20÷22 meters per second.
BACKGROUND OF THE INVENTION
In the state of the art, there are a plurality of devices and apparatus to coil strip or sheet leaving the hot or cold rolling train, which perform their function more or less efficiently.
One type of coiling machine particularly used in the hot rolling of strip or sheet is the downcoiler, which includes at least two coiling mandrels arranged in sequence and below the plane on which the strip or sheet which has to be coiled passes.
This coiling system, although it is widely used, has problems both regarding the speed at which the coils are formed and also regarding the quality of the sheet obtained, especially in the case of products which are particularly thin.
In fact, in the case of thin strip or sheet, when the leading end is bent under the plane on which it is fed in order to be coiled onto the downcoiler, there may be problems caused in the quality of the product.
Moreover, coiling is not carried out in a repetitive manner since it is performed alternately on two downcoilers placed at different distances from the shears.
Another problem which is also linked to the thinness of the strip or sheet to be coiled is that the strip rubs against the runway which delivers it to the coiling machine, which can cause a deterioration in the surface quality of the strip or sheet.
Another problem is that with the systems known in the state of the art with a guide belt for initial winding, the winding speeds must necessarily remain low. A further problem is the lead-in of the strip during the initial winding step when thin strip is being produced.
A further disadvantage is the distance between the shears and downcoiler downstream due to the consequent dangers of blockages of the leading end of the rolled stock, and the problems of losing temperature due to radiance.
There is also the problem of the trailing end of the wound strip which knocks against the equipment during the braking step of the coil. It is also a problem to support the coiling mandrel as a cantilever.
A further problem is how to guide the strip without causing damage to the surface thereof.
Document JP-A-1157713 describes a coiling device comprising two coiling mandrels onto which a rolled strip is alternately coiled.
The coiling of the strip begins with a first mandrel in a first position; then, after some coils of strip have been coiled, a turntable rotates and inverts the positions of the mandrels, while the strip continues to coil onto the first mandrel.
The first mandrel moves to a position to complete coiling and to discharge the coil, while a second mandrel moves to a start-of-coiling position.
When the coil has reached the desired size on the first mandrel, a shearing assembly arranged upstream intervenes on the strip and the leading end thereof is diverted towards the second, empty mandrel, also because there is a deflector roller and a lower guide.
Between the shearing assembly and the turntable there is a guide blade, the function of which is to distribute and deflect the leading end of the sheared strip in order to send it in the direction of the new mandrel, keeping the trailing end of the strip guided in the direction of the mandrel which is completing the coiling.
To this end, the guide blade has a triangular shape defining a peak facing the shearing means and the deflector roller, the peak being defined by two sides, an upper side cooperating with the lower face of the strip and with the mandrel which is completing the coiling, and a lower side cooperating with the upper face of the strip and with the new mandrel.
The upper side has no pneumatic supporting means and its only function is to prevent the final extremity of the trailing end of the strip from falling downwards, functioning substantially as a supporting base for the said trailing end during the end-of-coiling step.
The lower side, on the contrary, is supplied with pneumatic blowing means which serve first to deflect and then to press the leading end of the sheared strip against a lower guide during the start-of-coiling step on the new mandrel.
The solution of JP'713 does not solve any of the shortcomings explained above; on the contrary, it accentuates them by causing the strip to slide both on the upper side of the guide and also on the lower guide onto which the strip is pressed; nor does it control in any way the knocking of the trailing end when the coil is braked.
The present applicants have designed, tested and embodied this invention to overcome the shortcomings of the state of the art by providing a functional and extremely efficient solution both operationally and in terms of the quality of the product.
SUMMARY OF THE INVENTION
The invention is set forth and characterised in the main claim, while the dependent claims describe variants of the idea of the main embodiment.
The purpose of the invention is to provide a coiling machine for thin strip or sheet, which is provided with the suitable means to guide the leading end of the rolled stock towards the coiling elements and which is suitable to solve efficiently the above-mentioned shortcomings and in particular to guarantee efficiency, functionality and rationality to the coiling operations.
According to the invention, the coiling machine comprises, upstream of the turntable assembly and downstream of the shears, at least a first guide blade arranged above the plane of feed of the rolled stock to occupy a substantial part of the segment between the shears assembly and the turntable assembly to function as a fluid guide for the rolled stock towards the mandrels, the guide blade including at least a working position substantially parallel to the plane of feed and being provided with means to emit at least a jet of air and/or liquid against the upper surface of the rolled stock.
According to a variant, there are two movable guide blades, one below and one above the plane of feed of the rolled stock.
According to the invention, the movable guide blades include slits on their surfaces which cooperate with the plane of feed of the rolled stock; the slits emit jets of air, liquid or a mixture thereof to support the rolled stock which is to be sent for coiling.
The pneumatic, hydraulic or mixed support prevents problems caused by friction on the surface of the rolled stock, which are considerable in the case of thin stock as in the invention and therefore it prevents a deterioration of the surface quality of the finished product.
Moreover, this support prevents the leading end of the rolled stock from overturning or bending, in the segment between the drawing-shears assemblies and the mandrel, and thus prevents risks of blockages or impact with the equipment.
According to a variant, in cooperation with the jets of air there are driven rollers travelling at a speed greater than that of the strip and which have the effect of thrusting the strip itself, thus preventing blockages.
According to a variant, the upper movable guide blade is associated with a second movable guide blade, rotatable on the first and carrying at least a sliding roller in the free head.
The movable guide blades have an operating position wherein they support and guide the rolled stock cooperating with the plane of feed of the rolled stock and a position wherein they are substantially excluded from the plane of feed so as not to create interference.
The upper guide blade, moreover, includes a third position which it assumes during the cycle and in the transition phase betwee

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