Fibres are generally used as stuffing in upholstery. In order to make upholstery as spongy as possible the fibres are often made into spongy fibre balls with a rather smooth surface so that the balls are resilient and also able to move in re- lation to each other, in order to make the stuffing as loose as possible. There are previously known devices for forming balls of opened fibres carried in an air flow. Due to the surface friction the opened fibres carried in the air flow are at- tached to each other forming floccules of different sizes and forms. These floc- cules are not as such suitable for a stuffing material as there are fibre ends pro- truding from them which easily are attached to fibres protruding from other floccules. Therefore the floccules are preferably formed into balls.

Such ball forming devices are known for instance from the US patent publica- tions 4,747,550 and 5,429,783. In these previously known devices the opened fibres carried in the air flow are formed into balls in the intermediate space formed by the inner wall of a cylindrical stator chamber and the periphery of a rotor arranged coaxially within the stator. A plurality of transverse discs are ar- ranged spaced from each other on the rotor shaft, whereby at the outer edges of the discs there are at mutual peripheral distances fastened radial blades having

outer edges which end at a short distance from the inner wall of the rotor cham- ber. Air and fibres are supplied to the lower part of the rotor chamber and blown from there further upwards, whereby the fibres are formed into balls in the in- termediate space formed by the outer edges of the blades and the inner wall of the stator chamber when they are carried upwards in this intermediate space.

Then the fibre balls are sucked from the upper part of the stator chamber into a cyclone separator where the fibre balls are separated from the conveying air.

The gap between the outer edge of the blades and the internal wall of the stator chamber is in these devices generally 4 mm, but it can be made larger depending on the length and other characteristics of the fibres to be treated. However, in these devices it is a cumbersome and time-consuming task to alter the gap. In order to adjust the blades the rotor chamber must be opened and the rotor re- moved from the rotor chamber, after which the fastening of each blade must be loosened, adjusted and refastened. The blades are situated in many planes, and each plane contains many blades, and thus it is obvious that the blade adjustment operation is quite tricky and takes a long time.

The object of the present invention is to remove the above-mentioned disadvan- tage and to provide a device of the type presented in the preamble of claim 1 for forming fibre balls of elongated fibres carried in an air flow, whereby the device is novel and original in that the stator chamber and the rotor are substantially conical and that they can be mutually positioned in the axial direction.

With the solution according to the invention the intermediate space between the inner wall of the stator chamber and the blades of the rotor can be adjusted in a rapid and simple manner so that is suitable for each fibre quality, without having to open the stator chamber in order to remove the rotor from it, and without having to loosen, adjust and refasten the blades and without having to rearrange the rotor into the stator chamber and close the stator chamber. Thanks to the conical shape of the combination of stator chamber and rotor said intermediate

space changes when the stator chamber and/or rotor is moved in the axial direc- tion. The intermediate space changes the more the larger the coning angle is, and the more the greater the axial movement is.

In a preferred embodiment of the invention the blades are located on a plurality of axial planes, so that the blades on one plane are peripherally displaced in re- lation to the blades in the adjacent plane or planes. The angle of displacement is preferably 3 to 5 degrees, for instance 4 degrees in relation to the blades on the next plane.

Further, the blades on different planes are preferably separated from each other by circular plates, which are transverse in relation to the rotor shaft and of which the top plate has a radius which is substantially smaller than the radial length of the rotors below it. These solutions present a particularly advantageous and ef- fective ball forming of elongated fibres. The blades are generally at a mutual distance of 20 degrees in the direction of the rotor periphery, whereby the blades are advantageously on 4 to 6 planes, for instance on 5 planes.

In a particularly preferred embodiment of the invention the combination of sta- tor chamber and rotor is in a substantially vertical position and widens down- wards, whereby the input opening is at the upper end of the stator chamber.

Thanks to the conical shape of the combination of stator chamber and rotor there is formed a so called tornado effect in the intermediate space between the stator chamber and the rotor when the gas flow accelerates as it propagates in a spiral manner towards the wider end of the conical combination of stator chamber and rotor. The velocity of the gas flow increases as the peripheral distance is in- creased but at the same time the time used for one revolution is kept substan- tially the same. As the velocity of the gas flow increases its pressure will corre- spondingly decrease, there is in other words created a pressure difference be- tween the ends of the combination of stator chamber and rotor, and this pressure difference tends to force the flow combination against that end of the combina-

tion having the larger diameter. When the combination of the stator chamber and the rotor is in a substantially vertical position and widens downwards the above mentioned effect is assisted by the gravity, and thus it is effectively secured that the small fibre balls move towards the output opening at the lower end of the combination.

It has been found that the forming of balls is particularly effective when a part of the blade is bevelled at the outer edge, on the trailing side as seen in the rota- tion direction, whereby the bevelling angle of the blades is advantageously about 5 to 45 degrees.

Further the forming of balls can be made more effective by means of heating elements in the sheath of the stator chamber, preferably with heating resistors covering the sheath, and by means of a shelf extending around the inner wall of the lower end of the sheath.

Preferably there is further at least one collecting funnel between the output opening and the lower end of the stator chamber for receiving the fibre balls.

The funnel is preferably connected to a negative pressure source for removing the fibre balls from the funnel and then for separating them from the carrying air in a manner known per se.

Further there can be a perforated separating chamber between the input opening and the stator chamber in order to remove excessive air from the fibre contain- ing air flow before it is supplied to said intermediate space.

Advantageously the rotor is axially positioned in relation to the stator chamber so that the intermediate space is 4 to 10 mm. Then the coning angle of the com- bination of the stator chamber and rotor is preferably selected such that an axial displacement of 10 mm between the rotor and the stator chamber corresponds to a change in the intermediate space of about 0.1 to 1.5 mm, for instance 1 mm

Further the speed of rotation of the rotor is advantageously controlled in a step- less manner.

A device according to the invention is designed so that it can be rapidly and easily adjusted to be suitable for fibres of very different lengths and qualities.

In order to increase the retention time it is possible to connect a plurality of in- ventive devices in series, and preferably so that the rotational speed of each de- vice can be individually controlled.

The invention is described below in more detail with reference to the enclosed drawings, in which: Figure 1 shows a partly cut side view of a preferred embodiment of the inven- tion; Figure 2 shows an end view of the same device, without its upper part; Figures 3a and 3b show in a cross section a vertical view of the combination of stator chamber and rotor axially adjusted in different positions; Figures 3c and 3d show details of figure 3a; Figure 4 shows a top view of the stator; and Figure 5 shows a partly cut side view of the device in figure 1 with its external devices.

In figures 1 and 2 the frame of the device is generally marked by the reference numeral 4. On the frame 4 there is detachably fastened a substantially vertical stator chamber 1 with a frustoconical form so that the chamber tapers upwards, whereby the stator chamber's sheath contains an electrically heated resistor ele- ment 23 which has been found to essentially increase the effect of ball forming.

Within the stator chamber 1 there is a rotor 2 arranged to rotate around a vertical

shaft 3, whereby the rotor has the same form as the stator chamber 1 but is lower. The rotor 2 is further axially adjustable in order to adjust the width of the intermediate space 14 formed between the inner wall 1'of the stator chamber 1 and the periphery of the rotor 2 according to the length and other characteristics of the fibres to be formed into balls. The positioning or control device is not pre- sented in more detail, as such means are obvious to a person skilled in the art and quite common in the industry. A net funnel 6 is arranged at the upper end of the stator chamber 1 having an input opening 5 at the upper part for directing the opened fibres carried by the conveying air into the stator chamber 1 and for re- moving excessive air through the holes in the net funnel 6 before that. At the lower end of the stator chamber 1 there is further a narrow shelf 24 extending around its inner wall 1'which has been found to improve the forming of balls.

Further below the lower end of the stator chamber 1 and fastened to the frame 4 there are two funnels 11 having output openings 7 at their lower ends for suck- ing out fibre balls and conveying air and directing them to a previously known cyclone separator (not shown) in order to recover the fibre balls. Further there is a top bearing 15 and a bottom bearing 16 on the shaft 3 of the rotor 2 (shown in figures 3a and 3b), and moreover, at the lower end of the shaft 3 there is a pulley 10, with which the rotor shaft is rotatably connected via the belt 9 to the driving mechanism 8 fastened to the frame 4 in order to rotate the rotor 2 around the shaft 3.

The combination of stator chamber 1 and rotor 2 is shown in more detail in fig- ures 3a and 3b. In figure 3a the rotor 2 is positioned in the higher position, and in figure 3b in the lower position in order to increase the intermediate space 14.

It can be seen that the coning angles of the stator chamber 1 and the rotor 2 are identical, but that the rotor 2 is lower than the stator chamber 1.

In relation to the shaft 3 the rotor 2 is divided by transverse discs 13 at mutual axial distances into five planes, of which discs the disc at the top has a substan-

tially smaller diameter than the other discs, as can be seen in more detail in fig- ure 4. The blades 12,12'are fastened between the discs 13 so that they are ver- tical and directed radially away from the shaft 3, so that their outer edges end at a short distance from the inner wall 1'of the rotor chamber 1. There are 18 blades 12,12'in each plane, which results in an angle of 20 degrees between the blades. Additionally the blades on one plane are laterally displaced in relation to the blades on the next plane, whereby the displacement angle is 4 degrees be- tween the planes, as can be seen in more detail in figure 4.

The figures 3c and 3d show that the blades 12 on the upper planes differ slightly from the blades 12'on the lower planes, which have outer edges bevelled on the trailing side, as seen in the rotation direction shown with an arrow, what has been found to be particularly effective in furthering the forming of balls. The bevelling angle is preferably about 30 degrees.

When the rotor 2 rotates around its shaft 3 it generates in the stator chamber 1 a downwardly directed spiral flow between the rotor and the inner wall 1'of the stator chamber 1, whereby the velocity of the flow increases as it passes down- wards because the distance of one revolution increases even though the time re- quired by one revolution is kept substantially the same. Correspondingly, the pressure of the flow decreases, and thus there is created a pressure difference between the upper and lower ends of the intermediate space 14 which pressure difference assists the flow of air in carrying the fibres and fibre balls downwards towards the funnels 11.

Figure 5 shows a device according to the invention with external devices before and after it. In figure 5 the device tearing up fibre bundles is generally marked with the reference numeral 17, from which the opened fibres fall onto the weighing device 18, and from there a predetermined weighed fibre charge is blown along the pipe 19 to the input opening 5 at the upper part of the rotor chamber 1.

From the output opening 7 at the lower part of the funnel 11 the fibre balls are directed along the pipe 20 directly to a stuffing device of pillows or correspond- ing articles, whereby the stuffing device is generally marked with the reference numeral 21. The stuffing device 21 is preferably a continuously operating de- vice, whereby it has at least two stuffing stations, to which fibre balls are alter- nately supplied. The conveying air is separated from the fibre balls by sucking air through the cover to be stuffed by a sucking device arranged after the stuff- ing station.

It is obvious that the invention is not limited to the embodiment shown in the enclosed figures, but the invention can be varied quite widely within the scope defined by the appended claims. Thus for instance the number, the form and the location of the blades in the rotor, as well as the number of planes can be widely varying. It is also possible that the combination of stator chamber and rotor wid- ens upwards, whereby the output opening is at the upper end of the stator cham- ber and the input opening at its lower end. With this solution it is easier to con- trol the forming of balls. The coning angle of the combination of stator chamber and rotor can also be some other angle than that shown in the figures, and it is not necessary that the inner wall of the stator chamber is exactly straight, but it may be slightly convex or concave in the same way as the periphery of the rotor.

However, regarding the manufacturing techniques it is advantageous that the wall is straight.