This invention concerns a high speed flying shears.
The flying shears according to the invention acts on the rolled stock, whether the latter be a round rod, wire rod, bar, etc., leaving the last rolling train.
The flying shears according to the invention is suitable to shear rolled stock travelling at up to 100-120 meters per second or more.
It is a known fact of the state of the art that the leading and trailing ends of the rolled stock leaving the last rolling train include along their length geometric deformations or inclusions which are not acceptable and therefore have to be eliminated. This is normally carried out at speed so as to obviate the times otherwise required for shearing by hand downstream.
In view of the very high speed of withdrawal of the rolled stock from the rolling trains the problem of arranging in line a flying shears providing sufficient assurance of precision, reliability and accuracy of shearing becomes ever more important.
Various disclosures of flying shears for use with rolled stock travelling at a high speed are known and employed in the state of the art.
Substantially efficient solutions are disclosed in FR-666.433, DE-804.056, GB-2,075,899 and FR-1.578.587 but have been found unsatisfactory for rolled stock travelling at very high speeds. In particular, these solutions cannot meet the shearing accuracy required.
IT-A-1.214.194 in the name of the present applicants discloses a very high speed flying shears which includes contrarotating blades and cooperates with a switch of a start-stop type. This switch is suitable to convey the rolled stock longitudinally and to move sideways so as to feed the rolled stock into the shearing area.
The circumferential positions of the contrarotating blades can be linked to the lateral position of the switch with a view to determining exactly the moment when the rolled stock will lie between the blades, this moment coinciding with the best position of those blades for the shearing operation.
This solution is satisfactory in itself but entails the drawback that the rolled stock leaving the shearing step is not correctly guided towards the stations downstream, and this situation involves vibrations and inaccuracies in directing the stock towards the respective channels. Moreover, the solution does not provide a natural deviation for the intake of the material downstream of the shears, whether the material be the main body of the rolled stock directed towards the winding machine or be the sheared ends directed towards the scrap shears.
Starting therefore from the teaching of IT-A-1.214.194, the present applicants have designed and achieved an improvement of the flying shears which overcomes the shortcomings of the state of the art and has the purpose of accomplishing further advantages.
This invention is set forth and characterised in the main.