TPT May 2009

P roduction & P rocessing of A utomotive T ube

Latest saw specifically designed for small diameters

RSA, a German sawing technology specialist, has launched the Rasacut XS, a high-performance circular saw for tube diameters from 6 to 25mm. The machine was developed as a response to recent technological developments in the field of circular saws that have generally been aimed at high output of the 10-100mm diameter range. The minimisation of variants in the automotive industry is leading to larger batches for the production of semi-finished products made from tube, hollow sections and solid bars. However, quality demands are also increasing. A machine concept aimed at a wide spectrum of workpieces can cope only to some extent with demands made by highly specific parts, eg line systems in the automotive sector, where extremely strict requirements are applied concerning the degree of purity and precision of the tubes. However, the large quantities allow comparatively low piece costs. Multi-cut or bundle cut saws are generally used for the production of large batches in the diameter range up to 25mm. However, aimed at an improvement in quality and lowering of piece costs, the new RSA development counts on the single cut. The fully automatic processing cycle – even for large fixed lengths of 2,000mm or longer – presents an essential advantage.

When working with bundle cut saws, tubes are manually bundled. The workpieces are counted, fixed with an adhesive tape and inserted into a prismatic guide that feeds the tube bundle to the saw. With the Rasacut XS, tubes are automatically singled and fed. This method also allows one person to operate several saws.

 The central clamping of workpieces facilitates the use of saw blades with small diameters and high speed

The new RSA system is beneficial during further processing of tubes after cutting. In case of bundle cut saws, fixed lengths can fall apart after cutting – the so-called ‘mikado effect’. The feeding of the tubular sections to another processing step, such as deburring, requires further logistics – either an automatic singling machine or the manual feeding of a magazine. The Rasacut XS can be modularly expanded into a processing centre, combining in one line the processes of sawing, deburring or facing and chamfering, checking of lengths, roundness or chamfer, cleaning and stacking. In the experience of the RSA developers and designers, another argument for the single cut concerns the quality of the parts. Apparent motions in the tube bundle or in the layer can lead to scratches on the tube surface. Due to minimal misalignments within the tube bundle, parts are outside of determined tolerance. RSA claims that the Rasacut XS achieves in a single cut output values that are as high as those of multi-cut or bundle cut saws – and depending on the dimensional

range, even more – due to the reduction of ancillary times. Material is fed by means of a gripper with an acceleration of up to 40 m/s². The next tube is fed during the current sawing process, avoiding a loss of time during the changeover to the next stock length. On the basis of the Rasacut XS output values, around 150 changeovers to the next stock length are required per hour for a tube with 8mm diameter and a fixed length of 250mm, for a stock length of the random material of 6,000mm. This example shows the importance of ancillary times with regard to the total output. As an example of output: round tube with a diameter of 12mm and a wall thickness of 1mm, material  Two gripper feeds reduce to zero the ancillary times for a changeover to the next stock length

 The newly developed Rasacut XS for tube diameters from 6 to 25mm

 The Rasacut XS

automatically singles the tubes from the crane bundle and feeds them to the saw

56 ›

M ay 2009

www.read-tpt.com