FOCUS ON COIL PROCESSING
There are several stages to sheet metal slitting , as outlined below :
■ Storage station : This is where the processed raw material and the workpiece is stored . For slitting , this is usually a big , broad roll of metal sheet .
■ Transport trolley : A trolley is used to move the workpiece from the storage station into the uncoiler . The unwinder unwinds the coil as it feeds the metal sheet into another machine for slitting .
Shears on a cut-to-length ( CTL ) line for heavy-gauge materials ( STAM ).
Slit steel strip ( image : Ib Andresen Industri .)
rotary / flying shears ; stackers and packing lines .
The lines can be fully automated throughout the entire process of unwinding , flattening , cutting and stacking , and often include the latest sensor technology to measure metal flatness and surface quality . These are technologically advanced lines that offer high levels of productivity and high-quality standards in surface finishing , flattening , cutting quality and , in some cases , seamless stacking .
Light-gauge lines can include coil cars ; uncoilers ; peeler tables ; levelling equipment ; mechanical and hydraulic shears ; looping pit machinery and stacking / material handling equipment .
The slitting process
■ Slitter : Once the material leaves the uncoiler , it is fed into the slitter . How this happens depends upon the type of slitting undergone by the material . The slitter is set to cut the material in several narrow sheets according to the order requirements .
■ Recoiler : The last stage of the process is the recoiler . It is the opposite of the uncoiler . The recoiler winds the different strips of materials neatly . In some cases , a tension device can be used to ensure that the coils are neat and firm .
Sheet metal slitting requires careful set-up of the slitting machine to avoid inconsistencies that could be caused by leaving the blades with too little clearance , too much clearance or without proper vertical clearance .
A slitting line ( Athader ).
Light-gauge cut-to-length ( CTL ) line from The Bradbury Group .
sectors such as the construction industry . The production lines can also produce small coils (‘ baby ’ coils ) with a length of approximately 30m in zinc , copper , aluminium , pre-painted steel etc . These are used , for example , to manufacture roofing parts in the civil engineering industry .
Cut-to-length lines
Cut-to-length ( CTL ) lines can process different materials such as cold- or hot-rolled steel ; aluminium ; galvanised steel ; pre-painted copper ; high-strength steel ; zinc ; stainless steel ; alloys etc . The lines can feature many different configurations , according to the type of material to be processed and the performance required . These can include start-stop cutting lines , with roller feeders ; continuous cutting lines with flying shears and continuous cutting lines with rotary shears .
CTL lines can feature a range of equipment such as decoilers ; levelling machines ; edgetrimming machines with scrap-choppers ; scrap winders or scrap wrapping machines ; cutting /
Slitting is the process used to cut a wide coil of metal into several narrower coils . The process is primarily used to cut thin materials lengthwise and features a machine fitted with circular blades . There are two main slitting modes : straight mode slitting and free loop mode slitting .
“ In straight mode slitting , the recoiler pulls the material from the uncoiler through slitters . If the uncoiler and slitter are driven only to feed the material to the recoiler , this is called pullthrough slitting . In driven slitting , the slitter is also driven during the process . In this process , the motors are synchronised to maintain a constant speed as the material moves through the line . Driven slitting allows the slitting of thinner sheets and a better edge quality for all thicknesses ,” explained Thyssen Krupp .
“ In free loop mode slitting , the material forms a free loop between the slitter and the recoiler . A tension device is placed in front of the recoiler to ensure that the coils are properly wound . This method is recommended for poorly shaped coils . Sometimes , a temper mill or a leveller can be added to the slitting line to correct defects in the incoming coil-like buckles , thickness variations and twists . This improves the quality of the slitted strips ,” it added .
An aluminium slitting line built for Decomecc by GEORG .
Automatic separators for slitting lines ( FAGOR ARRASATE .)
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