Technology of Raising
The function of a raising machine is to produce a hairy surface on a fabric, this effect is made through a series of needles that, with a mechanism that we will explain later, are penetrating the fibres, breaking and lifting them.
How does a Raising machine work
To better understand the function of the raising machine we should refer to the geometric figure of the epicycloids, for the moment we will explain how the raising machine works.
The scheme of a raising machine can be seen in drawing DIS.1; a series of rollers, that are called raising rollers, are placed on a flange with circular settlement, these rollers are covered by an ordered alignment of needles. The raising rollers are divided between "pileā€ and "counterpileā€ raising rollers, according to the direction which the needles are plied.
This particular can be noted on drawings DIS.2 and FIG.P.
The raising rollers are rotating on their axle, both series of pile and counterpile are rotating in the same direction.
The flange on which the raising rollers are fixed is also rotating on its axle.
The assembly of raising rollers fixed on two side flanges is called "main drumā€.
The fabric encircles and is sliding on most of the raising drum; it enters in one point that is called fabric entry, in this point a driven roller (called tension roller) is controlling the feeding of the fabric on the main drum.
The fabric leaves the main drum, pulled out by a roller called fabric speed roller, this roller in fact is controlling the sliding speed of the fabric on the main drum.
To resume, in a raising machine we have 5 different axles :
ā€¢ Main Drum;
ā€¢ Counterpile Raising rollers;
ā€¢ Pile Raising rollers;
ā€¢ Fabric tension;
ā€¢ Fabric Speed;
An important part of our speech about the raising machine will be dedicated on how these 5 axles have been driven and how the technology on this matter, has developed.
Going back to the drawing DIS.2 we can understand that during the action of breaking and lifting the fibres, some of them will be removed from the fabric and will stick to the raising fillet.
There are two main techniques to clean the raising fillet; one with a nylon brush and one with a metallic brush.
The Nylon brush is a system that was used in the old machines as it only needed a simple drive system, no synchronisation was needed.
The system with metallic brush needs a more complex drive system but ensures much better results and a more proper effectiveness. In fact the system with the metallic brush needs two brushes, one is cleaning the pile rollers and one is cleaning the counterpile rollers; these rollers must be perfectly synchronised with the main drumā€s rotation.
One of the main advantages of the system with metallic brush, apart from cleaning the raising fillet more efficiently, is to make a slight and continuous sharpening to the raising fillet. This increases the operative life of the raising fillet.
For this purpose our raising machines are equipped with a cleaning system with metallic brushes, placed under the raising drum, between the fabric tension roller and the fabric speed roller.
In the drawing FIG.R it is possible to see how the metallic fillet of the cleaning brush is cleaning the metallic fillet of the raising roller. Each brush is cleaning its respective roller, rotating in the same direction of the bending angle of the raising fillet. It is very important that the cleaning brush does not clean the raising fillet against the direction of the raising fillet otherwise the points of the raising fillet would be damaged and the raising quality would dramatically decay.
It sometimes happens that the fabric will break and wind to the cleaning brushes, a safety disconnection unit is provided to disconnect the brushes in case this happens and to stop the machine in the shortest possible time.
The safety disconnection unit is also provided with an automatic device that restores the synchronisation of the cleaning brushes rotation with the main drum.
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