TPT May 2007

Evaluation of flying shear cutoff Cutoff by shearing the tube/profile is only used in about 10 per cent of production mills. The most established company producing shearing machines is Thermatool, while Italian and Japanese companies are on the periphery of this sector. As mentioned, Attl a spol has been involved with this technology since 1996, and the company’s products have established a high level of design quality. This is especially the case when it comes to quality of cut, blade geometry, blade durability and theoretical understanding of the applied principles. In Attl’s line of flying shears, the company has focused on production mills with a maximum production speed of 160m/min, since this parameter applies to 70-80 per cent of the current production mills. For shear cutting of square and rectangular profiles Attl have used one axis type of cut, where the shearing unit can be adjusted ±12° against the diagonal of the rectangle. When cutting tubes, Attl selects the two axes type of cut, although a totally different movement of the blades is used compared with current producers of cutoff machines. Attl decided not to select the option of converting the pressing tool as other machinery makers have. Instead, the company has found a new way based upon a rotation of the tools against pins and a large area sliding seat, resulting in a small pressure per unit of area. This approach has brought with it longevity of contact planes and the whole cutting unit in general. The life of the cutting unit before a

› Figure 1 : A detail of a sawing unit KS 76x3.4 with flying saw cutoff – Aldas

middle maintenance repair of the sliding planes is 2.5 to 3.5 million cycles The tool life of the main cutting blade is standard. Using TiN blade coating, the main blade life in-between sharpening can be estimated as 15 to 30 thousand cycles. The life of the slitting blade in Attl machines is well above average. Common life of Alpha Cut blades of this type is usually 10 to 15 thousand cycles. Due to a special design of Attl’s slitting blade, the company has achieved a life of 120-180 thousand cuts. The life of the cutting jaws in-between grinding is 80-110 thousand cuts and it is possible

Evaluation of parameters for both dividing technologies

Hot blade saw

Minimal use

No future, very bad quality of the cut surface

Cold rotary saw machine Range of diameters and wall thicknesses

Remarks

Ø 10-38mm

Very good quality; production speed not effected

thickness 1.2-2.5mm Ø 16-63.5mm thickness 1.2-3.5mm Ø 38-102mm thickness 1.5-5mm Ø 76-138mm thickness 1.5-5mm

Very good quality suitable for mill speeds to 80m/min

Good quality; limited production speeds

Classic concept of cold rotary saw strongly reduces mill output.

Possible solution: Duo; Kvatro

For cutting rectangles using cold rotary saw, similar guidelines apply. Shearing modules Range of tube diameters Remarks Module SJ 38 Ø 10-38mm

Good quality. Speed of the cutting unit does not restrict output of the production line. Possibility of cutting so called service lengths 1-3m with mill speeds to 60m/min. Quality sufficient. Speed of the cutting unit does not restrict output of the production line. Possibility of cutting service lengths lengths 1-3m with mill speeds to 60m/min.

thickness 1.5-2.5mm

Module SJ 63 (76)

Ø 16-63.3mm

thickness 1.5-3.4mm

Module SJ 89

Ø 38-89mm

Quality sufficient. Speed of the cutting unit does not restrict

thickness 1.5-4mm output of the production line. Possibility of cutting service lengths 1-3m with mill speeds to 60m/min. The shear cutting of tubes with diameters larger than 89mm is not recommended for reasons of high technical costs. The problem can be effectively solved by using Alda s 138 or Alda s 200 Kvatro cold rotary saw.

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M ay /J une 2007