Patent Application
20120000959
This invention relates to rolling mills producing hot rolled rods, bars and the like, and is concerned in particular with an apparatus for guiding such products along curved paths.
In a conventional rolling mill, the hot rolled product, e.g., 5.5 mm rod, can exit the last finishing stand at a speed exceeding 100 m/sec. The rod is then guided by an apparatus commonly referred to as a “turn down” along a downwardly curved path into a laying head. The laying head forms the rod into rings which are received on a conveyor where they are subjected to controlled cooling as they are transported to a reforming station.
Conventional turn downs typically employ fixed curved surfaces to guide the products downwardly along the curved paths. A drawback with this arrangement is that such guide surfaces are rapidly eroded by frictional contact with the hot products, thus requiring frequent mill stoppages after only several hours of operation in order to replace worn components.
The objective of the present invention is to provide a turn down apparatus with improved resistance to wear, thus enabling mills to operate continuously for extended periods of time measured in days rather than hours.
A turn down apparatus in accordance with the present invention comprises a stationary support structure having an open bottomed channel following the contour of a downwardly curved path along which the hot rolled product is to be guided. The channel is defined by a top surface overlying the curved path, with sides extending downwardly from the top surface, and with ledges projecting inwardly from the sides. Wear resistant inserts are affixed in the channel. The inserts are arranged to line the top surface of the channel, with sides of the inserts overlapping the channel ledges, and with lengths of the inserts defining chords of the curved path.
In order to present a guide surface to the product that approximates the curvature of the curved path, the lengths of the inserts are kept to a minimum, advantageously between about 0.1-1.0% of the radius of the curved path.
The stationary support structure may comprise a conventional steel fabrication, and the wear resistant inserts may comprise tungsten carbide tiles affixed in place. Preferably, the tiles are bonded to the top surface, sides and ledges of the channel, with brazing being a preferred method of bonding.
These and other features and attendant advantages of the present invention will now be described in further detail by reference to the accompanying drawings, wherein:
With reference initially to
With reference additionally to
The channel 26 has a top surface 28 overlying the path P, sides 30 extending downwardly from the top surface, and ledges 32 projecting inwardly from the sides 30.
Wear resistant inserts 34 are arranged end to end in the channel. As shown in
In a preferred embodiment of the invention, the inserts 34 comprise tiles made of tungsten carbide or other wear resistant materials. The tiles are preferably affixed in place within the channel 26 by being bonded to the top surface 28, the sides 30 and the ledges 32. Bonding is preferably achieved by brazing.
The overlap of the insert sides on the ledges 32 provides a secure mechanical interlock which insures that the inserts remain in place in the channel, even in the event that the bonded interfaces are disrupted during mill operation.
As a product passes downwardly along path P, forces resulting from the change in direction urge it into contact with the wear resistant inserts 34 lining the top surface 28 of the channel 26. The enhanced wear resistance of the inserts enables the turn down apparatus to operate for extended periods of time, thus contributing advantageously to efficient operation of the mill.
