Metal deforming – With use of control means energized in response to activator... – Metal deforming by use of roller or roller-like tool element
Utility Patent
1999-07-07
2001-01-02
Tolan, Ed (Department: 3725)
Metal deforming
With use of control means energized in response to activator...
Metal deforming by use of roller or roller-like tool element
C072S008800, C072S012500, C072S205000, C072S365200
Utility Patent
active
06167736
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates generally to hot rolling of rod and bar products, and in particular to the avoidance of off gauge front (i.e., head) and tail ends.
In a conventional rolling mill, product is directed through a series of roll stands designed to roll alternating oval “O” and round “R” cross sections. The rolls are driven in a manner that ensures the product is maintained in a state of tension as a result of its being pulled forwardly through each successive roll pass. This tension affects the cross section of the product by “necking it down”. However, the front and tail ends of the product experience tension free rolling as they pass through the successive roll stands. Thus, the resulting product has oversized front and tail ends. These must be cropped and discarded, thus representing a loss of production. Moreover, these off sized front and tail ends cause increased wear of the guides and other associated equipment in the mill.
Therefore, there is a need for a technique for eliminating the off gauge front end and tail ends of continuously hot rolled products.
SUMMARY OF THE INVENTION
Briefly, according to the present invention, a system for controlling the front and tail end cross sectional area of a continuously hot rolled product in a rolling mill includes first and second individually driven roll stands arranged successively along a pass line in advance of a downstream group of roll stands. A controller adjusts the operating speed relationship between the first and second roll stands to achieve an increased level of tension in the front and tail end segments of the product passing between the first and second individually driven roll stands. The increased level of tension produces an anticipatory decrease in product cross sectional area sufficient to compensate for the lack of cross sectional area reduction resulting from the absence of interstand tension experienced by the front and tail end segments while being rolled in the group of roll stands.
To control the cross sectional area of the front end of the continuously hot rolled product, the controller commands a decrease in the speed of the first roll stand as the front end approaches the second individually driven roll stand, which is located adjacent to and downstream of the first individually driven roll stand. The speed reduction establishes the increased level of tension in the product segment between the first and second roll stands, when the front end enters the second roll stand. When the front end has passed the first roll stand, the controller commands the speed of the first roll stand to return to nominal speed to roll the product length between the front and tail end segments.
To control the cross sectional area of the product tail end, the controller commands a decrease in the speed of the first roll stand as the tail end approaches the second individually driven roll stand. The reduction of the speed of the first roll stand establishes the increased level of tension of the product between the first and second roll stands when the tail end enters the second roll stand. That is, the controller anticipates the arrival of the lengthwise ends at the second individually driven roll stand and decreases the speed of the first roll stand in a controlled manner to establish a desired tension in the segment between the first and second roll stands.
Advantageously, applying an anticipatory increase in interstand tension to the end segments of the continuously hot rolled product controls the cross sectional area of the front end and tail end of the product to minimize and optimally eliminate any necessity for front and tail cropping.
These and other objects, features and advantages of the present invention will become more apparent in light of the following detailed description of preferred embodiments thereof, as illustrated in the accompanying drawings.
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Morgan Construction Company
Samuels Gauthier & Stevens
Tolan Ed
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