Posted to News on 27th Jan 2015, 17:25
Servo technology increases air filter production by 70 per cent
For their new generation air filters production machines, Keilmann Group near Frankfurt chose Lenze servo drives and achieved a 70 per cent increase in output compared with previous frequency inverter-driven machines. The new machine produces what are known as pocket filters commonly used in air handling systems. Pocket filters consist of a number of panels of filter material that are cut to a waisted profile and stitched together. Lenze servo drives control the material in- and outfeed plus dynamic positioning of the sewing heads at up to 10 stiches per second.
Pocket filters are used in groups of 3-12 pairs held in a frame that forms the shape with one end open. The assembly has a high surface area that can efficiently remove dust from the air with the minimum of pressure loss. Applications are widespread including the pharmaceutical industry and healthcare, spray booths, clean-rooms and general HVAC ventilation. Filter materials are glass-fibre or synthetic and in both cases the low density and relative softness create a challenge for precise material handling at speed. The need for exact synchronisation and positioning of the sewing heads led Keilmann to opt for Lenze servo technology.
The upper and lower lengths of material are pulled from a reel into the sewing area where a multi-needle station sews them into variable lengths across the web, followed by fixing with a hot-melt adhesive. Next the sides are waisted by the precisely positioned sewing heads, the pockets are cut to length and then fed out into the stacking area. The multi-needle sewing station strokes at up to 10 stitches per second and with varying thread lengths of 20-60mm between the two webs of material. To ensure the needles enter the material cleanly without tearing the sewing station must be precisely synchronised with the travel of the filter material.
The Lenze drive system uses servo drives of the 9400 series. Linked by CANopen, they are synchronised with "electrical shaft' software. Lenze MCS synchronous servo motors were selected for their low inertias and peak torque capacity up to four times nominal. Rather than a conventional option of planetary gears, the motors are connected to Lenze GKR bevel gearboxes. Externally resembling worm gearboxes, the GKR design is based on bevel gears giving efficiency of 94 per cent plus, with virtually no wear and very low backlash and lower costs than planetary designs.
For fast data processing the positioning system is integrated into the Lenze 9400 servo drives. On the cross-cutter that divides the material web into individual pockets, KSL use the Lenze "flying saw' drive system as a ready-made technology module. This achieves continuous movement of the web rather than a stop-start motion with buffering. The flying saw software is part of the suite of motion software that Lenze call "FAST', consisting of technology modules with a clear structure and proven high performance.
The KSL FPS300 filter pocket system demonstrates big gains from use of the Lenze servo system. The target for this machine was 20 m/min but 24 m/min was achieved. This is a 70 per cent increase from previous machines and represents 40 pocket filters per minute with a length of 600mm. The success can be attributed to a partnership with on one side the Keilmann expertise in handling non-woven fabrics, and on the other the drive and automation know-how of Lenze.
To learn more about Lenze servo drives please visit the website at www.lenze.com.
