EP0879905A1 - Method and apparatus for the detection and removal of foreign substances in fibre material - Google Patents

Abstract

To detect and separate impurities in fibre materials, and especially in raw cotton, the fibre material is taken from the pneumatic transport feed channel (4) and transferred to the surface of a continuous and moving transport system (19) for onwards movement. The fibre material is carried past a separation station, where the impurities are taken from the fibres. After passing the separation unit (3), the fibres are taken from the continuous surface and transferred preferably to a further pneumatic transport channel (5). Also claimed is an appts. with a fibre transport formed at least partially by a continuous conveyor surface (19), where the fibres are laid and carried past the separator (3), which is controlled by a sensor (2) which detects the impurities.

Description

The invention relates to a method for recognizing and eliminating of foreign substances in fiber material according to the generic term of claim 1. Concerning the device the invention also a device according to The preamble of claim 9. Such methods and devices serve in particular in a blow room foreign substances such as. Cords, plastic tapes, wires, etc. the raw cotton delivered.

There are already comparable methods and Devices known in which the fiber material in relative loosened form pneumatically and / or in free fall on Sensor field is passed. For example, the DE-U-296 04 552 a device in which the fiber flakes in an air flow through a fiber transport line are transported through, with an optical sensor system and a separator of the fiber transport line assigned.

According to another working principle, the fibers are in compresses a shaft into a nonwoven fabric, the Shaft through a conveyor belt at least on one side is formed. The sensor field is in the area of this shaft Arranged and foreign substances are removed after leaving the Separated shaft from the nonwoven. Such a thing The method is described for example in DE-A-43 40 173.

The efficiency of foreign material detection is in the air flow better than in the compressed nonwoven. In addition, in Airflow worked at a higher feed rate and the foreign material excretion is also more efficient, i.e. it will only be a small proportion pure fibers excreted together with the foreign material. There is, however, a certain disadvantage to detection and excretion in the airflow in that the way the foreign matter on the reaction path between sensor field and Replace the discharge device, not exactly checked can be. Air turbulence can, for example lateral path deviations take place, which affects the subsequent excretion has a negative impact. Especially at a selective excretion, such as that used in DE-A-43 40 173 is provided, a lateral effect Deviation of the foreign matter such that it may is not eliminated at all. For devices that in For this reason, free air flow has been used by a selective elimination based on the width of the Feed path apart.

It is therefore an object of the invention to provide a method of to create the type mentioned, in which the feed path the fibers and any foreign substances contained therein after passing through the sensor field until reaching the Precipitation device predetermined as precisely as possible and can be controlled. In particular, the Benefits of working in air flow can be exploited without the disadvantages of compressing the fibers into one To have to accept fiber fleece in the field of sensors. In particular, should also refer to when working in airflow the width of the feed path with a selective elimination high efficiency. This task is in procedurally solved with a method that has the features in claim 1.

By storing and carrying the fiber material on the endless surface of a continuous conveyor can be a precise control of the transport route can be achieved independently of density and structure of foreign substances. A foreign substance who has reached the surface once will this straight on the most direct route to the separator transported without lateral deviations possible are. The foreign substances are eliminated immediately away from the surface, at one point in time whose speed and feed path are still exact is defined. With the help of the endless surface of the continuous conveyor the reaction path can be curved, so that space is required even for relatively long reaction distances can be reduced. In terms of the device the object of the invention by a device with the Features solved in claim 9.

The fiber material on the surface is particularly advantageous a rotating sieve drum and at least sucked in there by means of a vacuum. At A pneumatic delivery becomes the transport air largely removed. A sieve drum as a continuous conveyor can be structurally easily arranged and in terms of their Control peripheral speed precisely. Of course the continuous conveyor can also be perforated Conveyor belt are formed that are over a certain Let the line put under negative pressure and that by two or more pulleys is deflected. The fixation on the endless surface does not necessarily have to be due to negative pressure respectively. Mechanical fixation would also be conceivable Needles, slats, etc. The fixation does not have to be mandatory either be such that the fibers or foreign substances cannot move are kept on the surface. A minor one Oscillation is conceivable and can be done, for example, with the Solution with a drum due to the centrifugal forces not completely exclude. The only important thing is to carry it on the surface at a constant speed and on the same level with no lateral deviations. In the direction of transport running guide ribs on the surface of the continuous conveyor adjacent housing inner wall favor the path stability of the fiber material.

A special optimal transfer from a pneumatic Feed conveyor line to the surface of the screening drum arises when the fiber material tangent to the surface the sieve drum is brought up. In this way finds practically no brisk change in speed when Impact of the fiber material instead of the surface. It Of course, it would also be conceivable for the fiber material to be radial to hit the drum. Also an unpressurized one Scattering the fiber material would be conceivable, both on the surface of a screen drum, as well as on the surface a conveyor belt.

The conveying speed of the continuous conveying means is preferably about the same size as the conveying speed of the Fiber material in the pneumatic feed conveyor line. On this ensures that the fiber material is roughly in the same density is distributed on the continuous conveyor, how it is fed. This will also make it uncontrolled Turbulence largely avoided.

The fiber material can already be placed on the surface of the continuous conveying device is guided past the sensor field be, the sensor field for example on the pneumatic Feed conveyor line can be arranged. This has the Advantage that e.g. on both sides of the feed conveyor line optical sensors can be arranged, which by Monitor glass panes in a specific field. The sensor field can be arranged very close to the continuous conveyor, so the fiber material immediately after the sensor field is captured by the continuous funding. Alternatively, you can the sensor field but also directly on the surface of the Continuous funding may be arranged, the sensor arrangement attached inside or outside the endless surface can be. The sensor arrangement can have sensors based on different physical principles work. Line scan cameras, electromagnetic, are conceivable Sensors, infrared sensors, X-rays, etc. Also one Combination of different sensor types in a row possible.

Foreign matter can be caused by applying pressure or Vacuum removed from the surface of the continuous conveyor will. With a sieve drum or with a perforated one Conveyor belt can have a pressure nozzle arrangement be arranged on the back of the surface, with the help of which a pressure surge through the surface and across Transport direction can be generated. Alternatively or additionally can also have a brief vacuum above the surface generated to suck foreign matter. Alternatively but would also be mechanical means for removing foreign substances conceivable. For example, club arms could be over be arranged on the surface of the continuous conveyor, which foreign substances knock off the surface and which can also be operated individually for selective excretion are.

The fiber material is preferred after the separation device by mechanical means, for example by at least one release roller, from the surface of the continuous conveyor decreased. That way, again a dissolution of the fiber material instead, so that it is in a pneumatic discharge conveyor line can be transported further can. But it would also be conceivable to replace the controlled and cleaned fiber material by means of overpressure or To cause negative pressure.

As already mentioned at the beginning, the procedure is special suitable that based on the width of the surface of the Continuous conveyance only selectively on the separation device Sections that are operated on the feed path of a previously determined foreign substance. The high lateral stability the feed path allows it to be very targeted numerous relatively short sections. In order to prevents unnecessary fiber material from being excreted which is not contaminated. So it can be related to the width of the surface of the continuous conveyor several Individual sensors can be arranged, each a single section are assigned to the separation device. The Individual sensors and / or individual sections can also be used Groups can be summarized, each in groups react.

Figur 1

eine Vorrichtung mit einem Unterdruckförderband als Stetigfördermittel,

Figur 2

eine Vorrichtung mit einem Lamellenförderband als Stetigfördermittel,

Figur 3

eine Vorrichtung mit einer Siebtrommel als Stetigfördermittel,

Figur 4

ein alternatives Ausführungsbeispiel zur Vorrichtung gemäss Figur 3, und

Figur 5

eine perspektivische Darstellung einer Siebtrommel mit mehreren Einzelsensoren am Sensorfeld und mit mehreren Einzeldüsen an der Ausscheidevorrichtung.

Further individual features and advantages of the invention result from the exemplary embodiments described below and from the drawings. The drawings are highly schematic and only show the general principle of operation. Show it:

Figure 1

a device with a vacuum conveyor belt as a continuous conveyor,

Figure 2

a device with a slat conveyor belt as a continuous conveyor,

Figure 3

a device with a sieve drum as a continuous conveyor,

Figure 4

an alternative embodiment to the device according to Figure 3, and

Figure 5

a perspective view of a screen drum with several individual sensors on the sensor field and with several individual nozzles on the separating device.

FIG. 1 shows a condenser 7 at the input of the device, in which the fibers from the conveying air in a known manner be separated so that they are loosened up by one Opening roller 11 depressurized and in free fall in the direction of the arrow b through the feed conveyor line 4 to the surface of a perforated conveyor belt 8 fall. The conveyor belt is around Deflection rollers 10, 10 'and 10' 'stretched and moves with constant speed in the direction of the arrow a.

Under the surface of the perforated conveyor belt is one certain route separated with a vacuum chamber 9, on which continuously creates a vacuum. over a sensor array 1, a sensor arrangement 2 is arranged, which reacts to foreign material. Sensor field 1 could also be arranged in the area of the feed conveyor line 4. The sensor arrangement can have sensors which optical, acoustic, infrared, x-ray or other physical Process sizes.

Immediately after the section kept under vacuum the conveyor belt, the separation device 3 is arranged. It essentially has a pressure nozzle arrangement 6 the surface of the conveyor belt 8. With their help a pressure surge is generated through the conveyor belt, so that foreign material in the adjacent foreign material container 12 is thrown. Immediately after the Separation device 3, a pair of removal rollers 13 is arranged, which the fiber material in the direction of arrow b in a Discharge conveyor line 5 feeds. In the discharge conveyor line the fiber material is suctioned off.

In the exemplary embodiment according to FIG. 2, there is continuous funding from a perforated slat conveyor belt 14, which is stretched around the deflection rollers 10 and 10 '. The ribbon turns at a constant speed in the direction of the arrow a.

The fiber material is fed under pressure on the right Angle on the surface of the conveyor belt in a pneumatic Feed conveyor line 4 in the direction of the arrow b. At the The surface of the conveyor belt becomes the fibers from the conveying air separated, similar to a condenser. Through the Perforation of the conveyor belt flows the air in the direction of the arrow c further through an intermediate connector 15 between the two Runs of the conveyor belt into a pneumatic discharge conveyor line 5. The fiber material is between the lamellae of the Conveyor belt held and transported. A formwork 16 forms a conveyor channel together with the conveyor belt. The sensor field 1 is covered by a section of the pneumatic feed conveyor line 4 formed. this section consists of transparent side walls, the Sensor arrangement 2 is formed by line cameras, which apply the sensor field on both sides.

The separation device 3 is behind the run of the conveyor belt arranged. It also consists of a pressure nozzle arrangement 6, with the help of foreign material through a Opening 17 in the casing 16 into a foreign material container 12 can be ejected. When not activated Pressure nozzle arrangement is the fiber material over the Opening 17 pushed away and arrives at the entrance of the discharge conveyor line 5 again under the influence of the conveying air for further transport.

In the exemplary embodiment according to FIG. 3, there is continuous funding from a rotating drum 19, which on not shown here in the direction of the arrow a is rotatably mounted. The feeding of the fiber material takes place in the direction of arrow b in a pneumatic feed conveyor line 4, the tangential to the surface of the screening drum 19 is introduced. A drum casing 28 forms thereby a curved channel through which part of the conveying air flows in the direction of arrow c.

The sensor field 1 is arranged directly in front of the drum. The sensor arrangement 2 is equipped with line cameras whose optical axes via deflection mirror 18 onto the sensor field 1 are directed. Alternative sensor arrangements would also be here conceivable, e.g. Infrared sensors.

Within the drum 19 is by means of a relative to Drum-fixed inner chamber 27 a vacuum sector 20th delimited, which extends over approx. 180 °. This vacuum sector is by means not shown here a lateral pipe connection permanently with a vacuum pressurized so that most of the conveying air passes through the openings of the sieve drum penetrates. The sieve drum itself can be built up in two layers, for example. An inner, mechanically stable layer is rectangular Provide openings in a regular arrangement. As the outside Layer can be covered with a fine mesh be provided.

Approximately diametrically opposite the point of impact of the fiber material The separation device 3 is on the drum surface arranged. It has a pressure nozzle arrangement 6 inside the inner chamber 27. On the same level as the pressure nozzle arrangement a connecting channel 23 is arranged to a foreign material chamber 24 leads. The connection channel 23 is closed in the idle state with a flap 21 which a flap actuator 22 can be activated. At the same time with the pressure nozzle arrangement 6 also the flap drive 22 activated so that foreign material is combined via the pressure surge with a suction in reaches the connecting channel 23.

The foreign material chamber 24 is operated via a suction fan 26 permanently pressurized. The suction fan sucks air through a filter 25. Once the flap 21 is opened, the foreign material is also subject to Suction of the fan 26. Safe storage in the Foreign material chamber 24 is thereby ensured. That from Foreign material freed fiber material is after the separation device 3 on the removal roller pair 13 from the drum detached and in a loose form in the pneumatic discharge conveyor line 5 delivered in the direction of arrow b.

The peripheral speed of the screening drum is the conveying speed adapted and can in the feed conveyor line up to 15 m / s. With a drum diameter of 750 mm this results in a speed of approx. 400 U / m. The order of the sensor field 1 relative to the separation device 3, that is the actual reaction distance depends primarily on the reaction time the separating device and the conveying speed from. For example, the response time is 0.1 s and the conveying speed 10 m / s, the reaction path must taking into account a safety factor 1.3 1.3 m. The dimensioning of the sieve drum, their diameter in particular is therefore largely also depends on this reaction time.

The exemplary embodiment according to FIG. 4 differs from that according to FIG. 3 only in that the sensor field 1 is arranged in the region of the surface of the screen drum 19 where the fiber material is on the sieve drum is filed. The sensor arrangement 2 can be sensors have inside and / or outside the drum are arranged. The excreted at the separation device 3 Foreign material is placed in an open foreign material container 12 ejected.

Various alternative combinations are evident of sensor arrangements, separating devices or Continuous funding is conceivable without changing the basic idea the invention is left. The width of the continuous conveyor is adapted to the specific circumstances. The cross section of the supply or discharge conveyor lines is preferably rectangular. The sensor arrangements can also across the entire width of the continuous conveyor have several separate individual sensors. Likewise, the Elimination device several arranged side by side Have pressure nozzles, each of which is selective from the individual sensors are controllable. This way you can refer to the width of the fiber material flow selectively excreted foreign material will. The physical functioning of the sensors and the necessary control means are known to the person skilled in the art known.

The principle of selective excretion is, for example shown in a highly schematic manner in FIG. On a sieve drum 19 is a sensor arrangement 2, which consists of several Individual sensors 29a to 29d exist. The separation device 3 in turn consists of several slit-like individual nozzles 30a to 30d, which are inside the sieve drum on a parallel line to the axis of rotation. Every single sensor a single nozzle is assigned to each. A foreign body 31 passes, for example, the individual sensor 29c, which is connected to the Single nozzle 30c transmits a control signal, which in the correct Time is activated and the foreign body through eliminates a pressure surge. The remaining individual nozzles 30a, 30b and 30d remain inactive, so that obviously only a very small subset of uncontaminated fiber material is eliminated. The individual sensors or individual nozzles can also be grouped together.

Claims (18)

Method for recognizing and eliminating foreign substances in fiber material, in particular in raw cotton, in which the fiber material is successively guided past a sensor field (1) and a separating device (3) and is continuously monitored by a sensor arrangement (2) which reacts to foreign substances, whereby upon detection of a foreign substance, the contaminated part of the fiber material is excreted by the separating device, characterized in that that the fiber material is preferably removed from a pneumatic feed conveyor line (4) and placed on the endless surface of a continuous conveyor means (8, 14, 19) and carried along by it, that the fiber material on the continuous conveyor is guided past the separating device and that foreign substances are removed from the surface, and that the fiber material is removed from the surface of the continuous conveyor after passing through the separating device (3) and is preferably fed back to a pneumatic discharge conveyor line (5). A method according to claim 1, characterized in that the fiber material on the surface of a rotating Sieve drum (19) is deposited and at least one Sector is sucked in there by negative pressure. A method according to claim 2, characterized in that the fiber material tangent to the surface of the drum (19) is introduced. Method according to one of claims 1 to 3, characterized characterized that the conveying speed of the continuous conveyor is about the same as the conveying speed of the fiber material in the pneumatic Delivery line at the feed. Method according to one of claims 1 to 4, characterized characterized that the fiber material before filing on the surface of the continuous conveyor at the sensor field is led past. Method according to one of claims 1 to 5, characterized characterized that foreign substances by exposure by means of overpressure and / or underpressure from the surface of the continuous conveyor are removed. Method according to one of claims 1 to 6, characterized characterized in that the fiber material after the separation device (3) by mechanical means from the Surface of the continuous conveyor is removed. Method according to one of claims 1 to 7, characterized characterized that based on the width of the surface of the continuous conveyor the separating device is only operated selectively on sections on the Displacement path of a previously determined foreign substance lie. Device for recognizing and eliminating foreign substances in fiber material, especially in raw cotton, with a sensor arrangement (2) reacting to foreign substances, with a separating device which can be controlled by the sensor arrangement (3), as well as with funding for the transport of the fiber material past you the sensor arrangement acted upon sensor field (1) and on the separating device (3), characterized in that that the funding is at least partially due the endless surface of a continuous conveyor (8, 14, 19) is formed, on which the fiber material can be deposited and is feasible. Apparatus according to claim 9, characterized in that the continuous conveyor is driven by a rotary Screen drum (19) is formed, the inside of which at least can be supplied with negative pressure via a sector is. Apparatus according to claim 10, characterized in that a pneumatic feed conveyor line (4) for the Fiber material tangent to the surface of the screening drum (19) is introduced. Device according to claim 11, characterized in that the sensor field (1) on the pneumatic feed conveyor line (4) is arranged. Device according to one of claims 9 to 11, characterized characterized that the sensor field (1) on the surface of the continuous conveyor is arranged. Device according to one of claims 9 to 13, characterized characterized that the surface of the continuous conveyor is air permeable and that the Elimination device (3) one on the back of the Has surface arranged pressure nozzle arrangement (6), with the foreign matter by a pressure surge from the surface are removable. Device according to claim 14, characterized in that the separation device (3) via a connecting channel (23) connected to a foreign material chamber (24) is, the mouth in the effective area of the pressure nozzle arrangement (6) lies. Apparatus according to claim 15, characterized in that the connecting channel (23) by means of a flap (21) can be closed together with the pressure nozzle arrangement can be activated and that the foreign material chamber (24) is connected to a vacuum source (26). Device according to one of claims 9 to 16, characterized characterized that according to the direction of conveyance the separating device (3) has at least one detaching roller (13) arranged on the surface of the continuous conveyor with which the fiber material can be removed is. Device according to one of claims 9 to 17, characterized characterized that each related to the width of the Surface of the continuous conveyor the sensor arrangement several individual sensors and the separation device have several separation sections, being in the conveying direction seen every single sensor or group a separation section of individual sensors (29a to 29d) or a group of separation sections (30a to 30d) is assigned and that each individual section or each group as it passes through a foreign substance the individual sensor assigned to it or the group thereof can be activated.

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