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Compact card - The future of carding
Universal carding unit for short staple webs with roller/ aerodynamical doffing
Our family tradition is known for innovative solutions for the non-wovens industry. The new HERGETH carding unit offers many new advantages for carding, operation and maintenance.The process starts with our new fine opening unit with mechanical doffing. This allows feeding the card with little air volume, but very fine opened fibres.
A
circular feed line 1) ensures that the fibres are well distributed
in the chute feed as the air travels with high speed all the way
across the width. Demixing of heavy and light tufts as it happens
in conventional chutes with dead-end systems is avoided. In the
chute the fibres are separated from the air by blade bars with a
progressive profile. This profile reduces the risk of fibres
twisting around the bars 2) and blocking the system. The chute is
made of segments that can be manually set for forming a profile. As
an option the chute can be fitted with an automatic regulation 3)
across the width. Ultrasonic transducers 4) measure the density of
the fibres in the chute. A PID regulation controls the actuators
that position the segments of the chute to achieve a uniform weight
across the width. The fibres enter the card by a large diameter feed
roll 5). The big diameter ensures a better control of the fibre
column entering the unit. The card works with unidirectional feed. A
feed table elongated by spring sheets 6) ensures control of the
fibres far into the nip point avoiding fibre blocks entering the
card. The three main cylinders 7) also have the same diameter like
the feed roll. By the use of three cylinders the fibres can be
gently sped up to the necessary surface speed and draft. The
carding is done by up to 15 carding strips 8) giving about the
carding power of a card with 15 rollers and strippers. The carding
strips are easy to exchange and have a moderate price. The carding
strips can be adapted to the material processed. If less carding
power is required the carding strips can be replaced by blanks. A
unique feature is the 2H roller 9). This roller skims the surplus
fibres from the second cylinder. The surplus fibres are sucked 10)
and reintroduced at the feeding machine reducing the chance of thick
spots and clouds. The carded fibres are doffed by a conventional
doffer 11) and delivered by two delivery rollers - one wire-wound
12), one fluted 13) - for webs orientated in machine direction. The
delivery unit can alternatively be equipped by one or two stuffer
rollers 14) for heavy webs.
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The carded fibres
can also be aerodynamically doffed for webs that are more
orientated in cross direction. The fibres are taken from the third cylinder by a stripping roll that throws the fibres into the air stream rather than sucking the fibres form the high speed cylinder. This allows the use of less air in the process and reduces the chance of nep production as is common with air stripping only. |
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A new way to produce 1:1 orientated webs is to use two aerodynamically doffed carding units that are orientated in + 45° and - 45° with respect to the main transport belt.
| By this, a web is created out of two layers which are orientated in an angle of 90° towards each other. With this unique process new non-woven products can be created. |
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For coarse products a machine with only one cylinder and no carding elements but with stripper roller will be used. This machine can form a web also with double-sided suction for very heavy webs. |
| Simple operation and maintenance were a main reason for creating the new card. Only two diameters of rollers allow low spare part costs. The rolls can be taken out with the bearings on the shaft in short time. This allows having a second set of rollers for a change in the product or for service. The drives of the rolls with large diameter are all concentrated in one drive tower sep arated from the carding unit. The cylinders are directly driven by cardan shafts avoiding belts, chains and hidden motors in the machine. The shafts are not affected by rotative lever load. The motors are always easy accessible. Feed, doffer and control cabinet delivery rollers and, if used, the stuffer rollers are servo-driven whereas the three carding cylinders and, if used, the stripping roller are frequency-controlled for instant adaptation of speed settings. All drives are SEW, the PLC is Siemens S7 type. |
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The vertical arrangement of the card makes it easy to
access the rollers and the carding elements. The setting of
the rollers is done in only one direction and the setting of
the carding elements can be controlled along the width of
the carding cylinders. The air flow in the machine is
top-down, reducing the fibre accumulation. All carding
cylinders and the feed roll are completely covered. Windows allow a view of the cylinders, even in applications with limited space. No sub-frame is necessary as the machine is bolted to pillars. On suction belts an automatic guide ensure the straight run of sort belts. The card can be integrated into a line with just two days of line stop. |