Abstract:
An apparatus is disclosed for receiving a helical formation of rings of hot rolled steel rod emerging from a laying head, and for depositing the rings on a conveyor for continued transport away from the laying head. The apparatus operates to engage and propel lower portions of the rings towards the conveyor at a first rate of travel, while engaging and propelling upper portions of the rings towards the conveyor at a second rate of travel. The first and second rates of travel are different and selected to cause the rings to topple onto the conveyor in an overlapping offset pattern.

Description:
BACKGROUND 
     1. Field of the Invention 
     This invention relates to an apparatus and method for receiving a continuous series of rings of hot rolled steel rod emerging from a laying head, and for depositing the rings in an ordered overlapping pattern laying substantially flat on a conveyor for continued transport away from the laying head. 
     2. Description of the Prior Art 
     In rod mills, it is common practice to pass hot rolled steel rod through a laying head where it is coiled into a helical series of rings. The rings emerging from the laying head are laid on a conveyor in an overlapping pattern where they are subjected to controlled cooling before being gathered into coils in a reforming chamber at the delivery end of the conveyor. 
     Rings formed from smaller diameter products, e.g., 5 to 26 mm rods, lie relatively flat on the conveyor, particularly when they are laid at elevated temperatures above about 950° C. However, experience has shown that the inherent stiffness of larger diameter products prevents the rings from assuming the desired substantially flat disposition on the conveyor. This is particularly true of the rings formed from the front and tail end portions of a billet length of the product, with the problem being further exacerbated by lower laying temperatures. Thus, for example when processing a 12 mm rod at a laying temperature of about 650° C., the leading and trailing rings will exhibit a tendency to resist laying flat and instead will protrude angularly upwardly from the conveyor. These upwardly protruding rings can disrupt orderly coil formation in the reforming chamber. 
     In U.S. Pat. No. 5,634,607 (Poloni), an attempt is made at dealing with this problem by temporarily blocking the outlet of the laying head in order to collect the leading rings into a densely packed hank which is then abruptly dropped onto the conveyor. A track assembly overlaying the conveyor is then employed to further flatten the rings passing therebeneath. 
     A drawback with this approach is that the densely packed leading rings of the accumulated hank do not cool at the same rate as the remainder of the overlapping non-concentric rings. This upsets end-to-end metallurgical uniformity of the resulting product. 
     Another drawback with this approach is that it does not deal effectively with the trailing rings, which also exhibit a tendency to resist laying flat as they are deposited on the conveyor. 
     An objective of the present invention is to achieve a substantially flat deposit of uniformly distributed rings on the conveyor, from the leading end to the trailing end of a billet length of product. 
     A companion objective of the present invention is to achieve the aforesaid flat deposit of rings without disturbing the uniformity of ring exposure to coolant application as the rings proceed along the conveyor to the reforming chamber. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, lower portions of the individual rings emerging from the laying head are engaged and directed towards the conveyor at a first rate of travel, and upper portions of the rings are simultaneously engaged and directed towards the conveyor at a different second rate of travel, with the difference between the first and second rates of travel causing the rings to be forcibly toppled onto the conveyor. The simultaneous duel engagement of the upper and lower ring portions produces a controlled deposit on the conveyor in a uniform overlapping pattern. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a view in side elevation of one embodiment of an apparatus in accordance with the present invention; 
     FIG. 1A is a partial view of the apparatus shown in FIG. 1, depicting an alternative embodiment of the mechanism employed to engage and advance the lower ring portions; 
     FIG. 2 is a sectional view taken along line  2 — 2  of FIG. 1; 
     FIG. 3 is a view similar to FIG. 1 showing an alternative embodiment of the invention; 
     FIG. 4 is a sectional view taken along line  4 — 4  of FIG. 3; 
     FIG. 5 is a graphical representation of typical rates of travel of the upper and lower ring portions with the embodiment shown in FIGS. 3 and 4; and 
     FIG. 6 is a view in side elevation of another embodiment of the invention. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     With reference initially to FIGS. 1 and 2, one embodiment of an apparatus in accordance with the present invention is shown in association with a conventional laying head  10  and cooling conveyor  12 . The laying head includes a curved laying pipe  14  rotatably driven in a known manner. Hot rolled steel rod  16  is received in the upstream end of the laying pipe and exits from its delivery end as a helical formation of rings indicated typically at  18 . The conveyor  12  is also of conventional design, having parallel mutually spaced rollers  20  driven in a known manner to carry the rings received thereon in an overlapping pattern away from the laying head to a reforming chamber (not shown) where they are gathered into large coils. 
     The lower portions of the rings  18  emerging from the laying head are engaged by a screw  22 . The screw is driven by a motor  24  carried on an arm  25  pivotally connected as at  26  to a fixed support  28 . The arm  25  is additionally connected as at  30  to the piston rod of an actuator  32 , the latter being operable to adjust the screw  22  and its drive motor  24  between the raised operative position illustrated by the solid lines in FIGS. 1 and 2, and an inoperative lowered position indicated by the broken lines in FIG.  2 . 
     The screw  22  has a frustoconical barrel with a spiral flange  33  on its outer surface defining a helical groove  34 . The rotational speed of the screw  22  is adjusted to match that of the laying pipe  14 , with the result that the lower ring portions are separated one from the other in the helical groove  34  and propelled downwardly by the spiral flange  33  at a first rate of travel towards the conveyor  12 . 
     The upper portions of the rings  18  are engaged by a second screw  36  driven by a motor  38  carried on an arm  40  pivotally connected at  42  to a second stationary support  44 . Arm  40  is pivotally adjustable by an actuator  46  for movement between the operative position illustrated by the solid lines in FIGS. 1 and 2, and an inoperative position indicated by the broken lines in FIG.  2 . 
     Screw  36  has a cylindrical barrel surrounded by a spiral flange  48  defining a helical groove  50 . The pitch of the upper screw  36  is steeper than that of the lower screw  22 . The rotational speed of screw  36  is also matched to that of the laying pipe  14 , resulting in the upper ring portions being separated one from the other in the helical groove  50  and propelled downwardly by the spiral flange  48  towards the conveyor  12  at a second rate of travel. The first and second rates of travel of the lower and upper ring portions differ, with the first rate of travel being the slowest, thereby forcibly toppling the rings  18  in a controlled manner onto the conveyor. 
     The controlled separation and advancement of the lower ring portions is particularly advantageous in that it promotes delivery of the rings in an ordered pattern onto the conveyor  12 . Without this feature, the lower ring portions exhibit a tendency to drag and bunch up as they leave the laying head, thus creating mini hanks which produce an uneven pattern on the conveyor. 
     In FIG. 1A, an alternative embodiment of the lower screw is shown at  22   a . The spiral flange  33   a  has a gradually diminishing pitch, which results in the lower portions of the rings  18  being propelled towards the conveyor  12  at a gradually decelerating first rate of travel. 
     While single screws have been described to engage and propel the upper and lower ring portions, it will be understood that the present invention also contemplates the use of multiple laterally disposed screws driven in a coordinated manner. 
     Referring now to FIGS. 3 and 4, a second embodiment of an apparatus in accordance with the present invention is again shown in association with a conventional laying head  10  and cooling conveyor  12 . The lower portions of the rings are again engaged by a screw  22  identical to that shown in FIG. 1. A plurality of brushes  52  having radially projecting bristles are arranged to contact the upper ring portions. The brushes are axially staggered to achieve an overlapping contact pattern, and are individually driven by motors  56  carried on a common support structure  58 . The support structure is rotatably adjustable about a vertical axis “A” for movement between an operative position as shown by the solid lines in FIG. 4, and an inoperative position at which the brushes are located 90° from their operative positions as shown by the broken lines in the same view. The brush bristles are suitably resilient, and of a heat resistant material such as for example UNS 517700, which can withstand repeated contact with the rings emerging from the laying head, without becoming permanently deformed, and without scratching or otherwise marring the ring surfaces. 
     The brushes  52  are rotatably driven at speeds selected to propel the upper ring portions downwardly towards the conveyor  12  at a rate of travel which exceeds that at which the lower ring portions are being propelled by the screw  22 . 
     FIG. 5 graphically depicts a typical speed relationship between the upper and lower ring portions where the lower ring portions are advanced by the mechanism shown in FIG. 1A, and the upper ring portions are directed downwardly by the mechanism shown in FIGS. 1 and 2. The lower ring portions have a gradually decelerating rate of travel depicted by line “a”, whereas the upper ring portions have a rate of travel as shown by line “b”, which first accelerates and then decelerates to finally equal the rate of travel of the lower ring portions when the rings finally topple onto the conveyor  12 . 
     In the embodiment shown in FIG. 6, the lower ring portions are engaged and propelled forwardly by the screw  22  illustrated in FIGS. 1 and 2. The upper ring portions are engaged and propelled downwardly by the pivotal elements  60  of an inclined chain conveyor  62  operating in conjunction with a separately driven horizontal track conveyor  64  parallel to and overlaying the cooling conveyor  12 . The conveyors  62  and  64  may be driven at different speeds, e.g., the conveyor  62  may be driven at a speed coordinated with the rotational speed of the laying head, whereas the conveyor  64  may be driven at a speed matching that of conveyor  12 . 
     Conveyor  62  is driven at a speed which propels the upper ring portions downwardly towards the conveyor  12  at a rate of travel which exceeds that of the lower ring portions. Once on the conveyor  12 , the rings are further pressed downwardly by the track conveyor  64 . 
     It will now be appreciated by those skilled in the art that with each of the above described embodiments, the rings emerging from the laying head are forcibly toppled onto the conveyor  12  to achieve a flat overlapping pattern. The lower ring portions are engaged separately and propelled forwardly at a controlled rate of travel which is slower than that which is simultaneously being imparted to the upper ring portions. This dual engagement and controlled forward movement promotes uniformity in the resulting overlapping pattern of rings on the conveyor.