Materials

  1. Tension roll is surface coated with Polyurethane which is softer than metal, but it is endurable to take friction and sharp burr on slit strip edge to guide slit strips running in steady way.
  2. Tension rolls is designed to produce tension by about 2% speed slower on tension rolls than recoiling speed. This approximately 2% speed differential can generate electricity feed-back to decrease the machine power consumption. The money saved years round can cover the expense for replacement of PU when the roll surface is critical damaged.

Leveler roll diameter design is a complex calculation including material tensile strength, palsticication ratio, roll clearance, roll deformation, 

For example, metal material of tensile strength 400 Mpa, the reference diameter of leveler rolls are below.

Ø50mm for material max. 2.0mmt.

Ø60mm for material max. 3.0mmt,

Ø70mm for material max. 4.5mmt,

If one leveler can't cover all the material thickness , two levelers or exchangeable double cassette levelers can be considered.

For example, one cassette leveler with Ø50mm rolls can manage material up to 2.0mm in thickness. but maximum material is 3mm in thickness, then another cassette with Ø60mm leveler rolls will fit. The product range of same cut-to-length line extended from 2mm thickness to 3mm thickness.

Some customers even choose levelers of Ø50mm rolls and Ø70mm rolls in separate two, so the product range is enlarged from maximum 2 mm to 4.5 mm.

Two types, stop-to-cut type with guillotine shear or non-stop cutting type with rotary or flying shear. The differences are as below table.

ItemType

Stop-to-cut

Non-stop cutting

Shear type

Guillotine shear

Rotary or flying shear

Shear drive

Hydraulic

Servo motor

Cutting process

Feeding – stop – waiting shear to cut (one cycle)

Non-stop feeding & shear tracking length to cut

Material thickness

0.2~ 25mmT

0.2~ 4.5mmT

Scratch on surface

No scratch

No scratch

Roll mark on surface

Depends on material

No mark

Critical required surface

Not recommended

Recommended

Productivity

As standard base

About 2~5 times higher

In short, the advantage of rotary shear and flying shear is faster production speed, no roller mark on material surface, and that of guillotine shear is cost lower.

EPC is the initial of “Edge Position Control” which is important for the quality products of both cut-to-length machine and slitting machine. 

The EPC starts functional from Uncoiler positioning to follow the side guide before leveler. 

EPC dynamically keep the material coil  edge aligned constantly so to make sure diagonal accuracy of cut sheets or edge straightness of slit strips.

If without EPC, especially when the thin material coil band is off edge line, coil band might get damaged on the edge whilst coping with side guides which try to force the band edge back to the line,