Method and apparatus for the trimming of strip, especially hot roll metal strip

Abstract

Sensors of the longitudinal edges and/or the width of hot roll metal strip are located immediately ahead of the trimming blades and are used to transversely adjust the trimming heads and/or the centerline position for the strip so that in subsequent trimming operations, the trim widths are identical at both sides. The cutting heads can be positioned in indentations at junctions between the successive segments of the strip.

We claim:  
     
         1 . A method of trimming longitudinal edges from metal strip which comprises the steps of: 
 (a) advancing metal strip to be trimmed along longitudinal edges of the strip along a trimming path in a longitudinal direction and engaging said strip at each longitudinal side thereof with a respective trimming shear head, thereby cutting a respective trim from the respective side along the respective longitudinal edge;    (b) measuring positions of the longitudinal edges and optionally a width of the strip at a location immediately upstream in said direction of the respective heads; and    (c) prior to engaging blades of said trimming heads with said strip for cutting trim of a given width from said strip, adjusting positions of said heads based upon results of the measurement in step (b) in a direction of the width of the strip and then engaging said blades with the strip.    
     
     
         2 . A method of trimming longitudinal edges from metal strip which comprises the steps of: 
 (a) advancing metal strip to be trimmed along longitudinal edges of the strip along a trimming path in a longitudinal direction and engaging said strip at each longitudinal side thereof with a respective trimming shear head, thereby cutting a respective trim from the respective side along the respective longitudinal edge;    (b) measuring positions of the longitudinal edges and optionally a width of the strip at a location immediately upstream in said direction of the respective heads; and    (c) adjusting a position of a centerline of said strip based upon results of the measurement in step (b), before, after or during engagement of blades of said shear heads with said strip whereby said strip centerline is positioned relative to the shear heads and blades thereof.    
     
     
         3 . The method defined in  claim 1  or  claim 2  wherein measurement signals are generated for adjusting positions of said heads or adjusting a position of a centerline of said strip and are applied to a strip centerline control unit.  
     
     
         4 . The method defined in  claim 1  or  claim 2  wherein individual strip segments are joined end-to-end to form a continuous strip having longitudinal edge indentations at each junction between individual strip segments, the blades of said shear heads disengage from said strip at said indentations and the positions of the shear heads or the centerline are readjusted on standstill of the strip while said heads are located at said indentations and for subsequent severing of trim of a given width from the strip.  
     
     
         5 . The method defined in  claim 4  wherein said trim is of equal width at both sides of said strip.  
     
     
         6 . The method defined in  claim 1  or  claim 2  wherein, for a continuous-length strip, a leading edge of the strip is initially positioned upstream of said shear heads, a centerline of said strip is adjusted relative to said shear heads to define a new band width to be trimmed during a standstill of the strip, and thereafter upon advance of said strip trims of equal width are cut from said strip at opposite longitudinal sides thereof.  
     
     
         7 . The method defined in  claim 1  or  claim 2  wherein, after adjustment of the shear heads with the respective blades and restarting of travel of the strip and during the trimming of the strip, possible offsetting of the strip centerline is counteracted by a centerline positioning mechanism and optional adjustment of the shear heads to a zero offset until the strip is centered between said shear heads at its centerline.  
     
     
         8 . The method defined in  claim 1  or  claim 2  wherein said strip is hot-rolled strip.  
     
     
         9 . An apparatus for trimming metal strip, comprising: 
 means for advancing metal strip to be trimmed along longitudinal edges of the strip along transport path in a longitudinal direction;    a respective shear head engageable with said strip at each longitudinal side thereof for cutting a respective trim from the respective side along the respective longitudinal edge; and    sensors for measuring positions of the longitudinal edges, a width of the strip and edge flaws at a location immediately upstream in said direction of the respective heads.    
     
     
         10 . The apparatus defined in  claim 9  wherein said sensors are optical or electrical sensors.  
     
     
         11 . The apparatus defined in  claim 10 , further comprising means for adjusting positions of said sensors in a direction of the width of said strip.