Coiling machines which are known to the state of the art are substantially divided into two categories, according to whether the axis of rotation of the mandrel or reel is vertical or horizontal.
Coiling machines with a vertical axis of rotation are based mainly on coiling inside containing cylinders, where the spirals are formed with the help of spiral-forming tools equipped with relative motion with respect to the containing cylinder.
This type of coiling machine generally does not ensure that a compact coil is formed, since the reciprocal movement of the spiral-forming tool and the containing cylinder is quite uncontrolled and since the stock which is being coiled is not subjected to a controlled tension.
Coiling machines with a horizontal axis of rotation normally allow to obtain much more compact coils, since the product to be coiled is wound on the central mandrel, which is made to rotate by a motor organ. In such coiling machines, the coil is made by means of successive, superimposed rings or layers, which are coaxial to the reel, and thus compact coils are obtained.
The state of the art includes a coiling machine wherein a curved element is arranged inside a containing cylinder, in which the spirals are formed and accumulate, and is kept substantially parallel to the inner surface of the containing cylinder.
In this coiling machine, while the containing cylinder is made to rotate, the curved element is made to gradually advance, parallel to the axis of rotation of the cylinder, and is removed from inside the coil when the latter has been completed.
Although this coiling machine is equipped with a device which facilitates the formation of the spirals of the coil, it does not ensure that a compact coil is formed, since the reciprocal movement of the spiral-forming tool and the containing cylinder is quite uncontrolled and since the stock which is being coiled is not subjected to a controlled tension.
The state of the art also includes a coiling machine located at the end of a rolling plant for the continuous production of iron bars, wire or round pieces, wherein a single plane product, obtained during a first rolling step, is sub-divided into a plurality of profiles which are given the desired shape in subsequent rolling operations. In this plant the rolled products thus obtained are conveyed, parallel to each other, towards the stationary coiling machine with a horizontal axis of rotation, which provides to coil them simultaneously, or in parallel, so as to form a plurality of coils on the same mandrel.
This coiling machine has the disadvantage that several profiles, which may even be different from each other, are wound onto the same mandrel, rotating at a set angular velocity, and therefore the coil formed is neither compact nor in the least controlled while it is being formed.
Moreover, coiling machines which are known to the state of the art do not guarantee a uniform temperature over the whole stock which has been rolled and coiled, with differences at the leading and trailing end and the centre; this gives a lack of uniformity of the metallurgical aspect over the whole coil of rolled stock.
The present applicant has designed, tested and embodied this invention to overcome the shortcomings of the state of the art and to obtain further advantages.