EP0824607B2 - Process and device for detecting and removing foreign substances in and from fibre material - Google Patents

Abstract

The polluted fibres are pneumatically conveyed in loose form from top to bottom in a presentation channel (1) past a sensor field. The sensor arrangement (2, 2') advantageously consists of CCD cameras operating in line. The continuous feed roughly in the direction of gravity permits the best possible tuning of the sensor arrangement and a higher through-flow rate.

Description

The invention relates to a method for detecting and removal of foreign matter into fibrous material according to the preamble of claim 1, as well as a Device for the practical implementation of a Such method according to the preamble of claim 7. Such methods and devices are primarily in spinning mills for cleaning Raw cotton used. Raw cotton is common with Foreign matter such as e.g. Lacing, jute or other Meshes, plastic parts, etc. interspersed, which in the spinning process like the cotton fibers themselves to be processed into yarn and which only with one considerable effort can be removed again. One is therefore anxious, these foreign substances already in the Cleaning out as completely as possible. The cleaning fiber material can also be used in other processing processes, such as. in the processing of mineral, synthetic or animal fibers Role-play.

When processing Baumwoltfasem in The cleaning of a spinning mill must be cleaned involved in a continuous work process be, the processing speed to detect and eliminate foreign substances upper and lower limits are set. An essential The factor here is the way in which the cotton flakes a sensor arrangement are presented, to achieve the highest possible recognition rate.

By "mittex 1/95, detection and elimination Foreign Substances in the Blow Room, Page 12 to 15 " a recognition method has become known the cotton fibers in the form of a compact Bandes on a conveyor belt of a sensor array to get presented. The densification of cotton too a band reduces the detectable by the sensors Overall surface, leaving foreign matter in the band are not recognized. The compression is also undesirable and the fibers must then be loosened again.

It has therefore been disclosed in EP-A-414 961 also already proposed the cotton flakes distributed over a larger cross-section in one Presentation channel pneumatically a sensor arrangement showcase. To the sensor used as sensors Cameras a proper identification of However, the promotion takes place intermittent from bottom to top, with am arranged a valve at the top of the presentation channel is that opens and closes continuously. The intermittent fiber transport is mechanically relative consuming and does not allow high production speeds. The undefined conveying speed concludes the use of certain detection methods out, and when detecting an impurity must always an unreasonably large subset excreted by cotton fibers.

It is therefore an object of the invention to be To provide method of the type mentioned, the with structurally simple means at high production speed a precise recognition and departure of foreign substances. Another task The invention consists in a device of the above to create said type, which saves space in a production line can be installed and the ever after application, the use of different detection methods allowed. This object is achieved according to the invention solved with a method that the Features in claim 1. In device-moderate The object is with a device with the features of claim 7 solved.

It has been shown that it is much more advantageous is, the fiber material in a loose form continuously from the top to the bottom of a sensor field. On the one hand, this is the expenditure on equipment significantly reduced. On the other hand, it can be done with it a relatively well-defined conveying speed in the area of the sensor field achieve what the use various detection methods allowed. Especially can also use linear color CCD cameras (Line Image Sensors) are used. All fibers and foreign matter, regardless of their density largely with the same conveying speed.

The fiber material is passed the sensor field on a presentation track, which is inclined to the vertical by 0 ° to 50 °.

Particularly good results have been found at a conveying speed in the presentation channel between 2 to 5 m / s, in particular between 3 to 4 m / s. If the continuous monitoring at the sensor field takes place after a free presentation distance of 0.5 to 1.2 m, the effect of gravity can be exploited in an optimal manner for keeping constant the conveying speed of objects of different density. A heavy body such as B. a stone or a metal part is subject to relatively low influence from the air flow of the normal gravitational acceleration of about 9.8 m / s ² , while a cotton fiber would float without air flow at a low speed down. At the aforementioned conveying speed after a drop distance of, for example, 40 to 80 cm, the speed of a heavy body is approximately the same as that of the fibers in the air stream.

The flow in the presentation channel can open be achieved in different ways. This is conceivable Blow in air at the top of the presentation channel with the help of a fan. But it can too maintain a negative pressure after the presentation channel can be obtained, e.g. by the pressure side of a fan via a suction nozzle with the lower end of the Presentation channel is connected. It is after The Venturi principle creates a negative pressure. The negative pressure but can also be generated by a fan be on the transport line for onward transport the fibers is arranged, in addition. Air is sucked in after the presentation channel. Preferably becomes the continuous flow in the presentation channel cumulatively upright by various means get as uniform a speed as possible to achieve. By fixed or adjustable Throttling can be over the entire channel cross section maintained uniform air velocity become. It is also conceivable, the throttles or the inserted Fans mechanically or electronically to regulate.

The flow can be under the presentation channel be redirected, with the elimination the contaminated subset in the area of the direction change or immediately afterwards. The inertia The foreign substances will become more targeted Exhaustion optimally utilized. An excretion but is also before the deflection in the vertical area possible.

Particularly advantageous is above the presentation channel arranged a distribution device for the uniform metering of the fiber material in the Presentation channel. It is conceivable, directly to arrange a condenser over the presentation channel, the channel possibly via a cellular wheel or the like fed. But it is also possible over the Presentation channel to arrange a hopper, in always kept a certain amount of fiber in stock becomes. The metering takes place from the hopper About discharge or. Opening rollers. An optimal speed the fiber material can be largely also by the tangential velocity of the Cell wheel or the opening rollers can be achieved. The Final speed is thus by mechanical and defined pneumatic means in combination

As mentioned in the introduction, became special achieved good results when the sensor assembly an electronic line scan camera with color sensor has, with the whole width of the presentation channel is detectable. Compared to matrix cameras, the Sensor field are kept very small, which saves a lot of space Accommodation allows. The linear Sampling also allows for easier programming and control of the whole system and shorter Reaction times. Line scan cameras finally make it possible also the lighting of the fiber material in the presentation channel in incident light and lilac to avoid of shadow effects. The lighting performance can be reduced and annoying reflections can easily be avoided unlike matrix cameras become. The CCD cameras are programmed that they are within a certain tolerance range on the hue, brightness and saturation of the Cotton fibers are set. Every change of the Color spectrum outside the tolerance width is called Deviation registered and can after appropriate Evaluation generate a control signal. Foreign substances, whose color is within the tolerance spectrum, can not be detected in this way.

Of course, the sensor arrangement but also still have sensors that respond to other parameters react, such as to different density, on different substances, etc. For this purpose e.g. X-rays, ultrasonic waves, electromagnetic Fields etc. are used. Especially Advantageously, the sensor arrangement additionally has at least a sensor that is in the range of ultraviolet or infra-red or near-infrared works. With such Sensors can also detect foreign bodies, which have approximately the same color as the Cotton fibers, however, made of a different material consist.

The excretion of foreign substances is done by the Use of a nozzle strip for blowing out impurities from the flow.

A particularly advantageous construction of the device results if these at least one feed module, has a sensor module and a separation module, between these modules optionally further Modules are installable. The modular design allows on the one hand a simple installation and maintenance the device. On the other hand, but also later additional components are incorporated, such as e.g. additional sensors etc.

Figur 1

einen Querschnitt durch eine erfindungsgemässe Vorrichtung in stark schematisierter Darstellungsweise,

Figur 2

einen Schnitt durch die Ebene A-A gemäss Figur 1, und

Figur 3

einen Querschnitt durch ein alternatives Ausführungsbeispiel mit schräggestelltem Präsentationskanal.

An embodiment of the invention is illustrated in the drawings and will be described in more detail below. Show it:

FIG. 1

a cross section through an inventive device in a highly schematic representation,

FIG. 2

a section through the plane AA according to Figure 1, and

FIG. 3

a cross-section through an alternative embodiment with tilted presentation channel.

The device shown in Figures 1 and 2 has a housing 22 in which a vertical, arranged in cross-section rectangular presentation channel 1 is. The two parallel side walls 7, T of the Presentation channels are as transparent slices trained, but could possibly also have a filtering effect exercise for certain wavelengths of light. On Both sides of the presentation channel are lighting fixtures 3 arranged.

The sensor arrangement consists of the two CCD cameras 2, 2 ', the presentation channel off Space saving reasons however over the two mirrors 8, 8 'apply indirectly. The optical planes 27, 27 'are arranged slightly offset from one another. Seen from the observation side respectively There is a background strip behind the presentation channel 6 arranged in the row level, the set Parameters for the fibers corresponds, so that the camera is not synonymous with empty presentation channel responds.

Above the actual presentation channel 1 an intermediate module 26 is arranged whose channel cross-section however, it is the same as the presentation channel. This intermediate module serves on the one hand as a fall and could on the other hand also with other sensors, such as Metal detectors or infrared sensors be fitted.

The air flow in the presentation channel is generated by a fan 4, the pressure side with an air inlet module 5 is connected. This module could be omitted if the flow is exclusive is generated in other ways. additionally the flow can be assisted by one Fan not shown here, after the Presentation channel arranged in the transport line is and primarily serves the material transport. About an air inlet duct 16 is thereby additional air sucked. The suction effect thus produced evidently causes a negative pressure in the presentation channel.

The feeding of the device with fibers via a condenser 9, to which a Flockenzufuhr 10 leads. Such condensers are those skilled in the art already known. They have a spinning one Screen drum 12, on which the flakes off be condensed out of the conveying air. The partial still dusty exhaust air is through the exhaust pipe 11 dissipated. Fall from the outside of the screen drum 12 the flakes by the action of centrifugal force again and then through a rotary valve 13 metered into the shaft.

Immediately after the curvature 15 is a Blasdüsenleiste 17 arranged, over one Ejection opening 18 leading to a collecting container 20th leads. In the ejection opening 18, a rotating Cell wheel 19 may be arranged to prevent backflow. Upon activation of the blast nozzle strip 17 also the cellular wheel 19 is rotated. The ejection opening and the tuyere could also in the vertical shaft area immediately below the Presentation channel be arranged. Instead of the cell wheel could be provided a short-opening flap become. If the pressure conditions allow it, the discharge opening does not have to be closed at all become.

The cleaned fibers are over the Transport pipe 21 discharged and get to the next Machine.

The device is constructed in modular design and includes a delivery module 23, a sensor module 24 and a separation module 25. These modules form the basic equipment. You can exchange or be supplemented.

The partially contaminated cotton fibers thus arrive from the direction of arrow a first in the condenser 9, then fall down against the presentation channel 1, focusing on the desired conveying speed to be brought. In optimal presentation form the fibers then pass the sensor field, where color different foreign bodies detected become. Exactly matched to the remaining drop distance is at a signal on the sensor array the blast nozzle bar is activated with compressed air. The nozzle bar can work linear or punctiform, so that only a specific segment of the width the flow can be eliminated. This Of course, a corresponding evaluation the sensor signals on the sensor assembly ahead.

FIG. 3 shows an alternative embodiment, in which the presentation channel 1 under a Angle of slightly less than 45 ° inclined to the vertical is. Otherwise, however, the sensor module 24 is approximately the same structure as in the embodiment according to Figure 1. The metering of the fibers from the condenser 9 also takes place via a cellular wheel 13. The admixture of air through the fan 4 takes place here at an angle to the conveying direction of the flakes.

Something different is also the exit the foreign body in the separation module 25. The ejection opening 18 is opposite to the Blasdüsenleiste 17 in the Vertically arranged and leads without a cell wheel or the like directly to the collecting container 20. The passing on the flakes in the transport tube 21 via a open funnel 14, being at the entrance of the funnel Room air is sucked in.

By WO 89/01832 is a device for sorting Fiber material in a pneumatic conveyor line has become known. The material is thereby successively at a monitoring station and at a lateral opening in the delivery line past. From arranged opposite the opening nozzles a gas pulse can be triggered across the channel. As soon as the monitoring station determines a foreign substance to be eliminated, this is through the opening into a substantially gas-tight chamber blown out.

EP-A-285 602 discloses a method and an apparatus for detecting and removing foreign substances from raw cotton known. To detect foreign fibers is thereby the raw cotton irradiated with X-rays, with density fluctuations can be determined. To this end The cotton material must be dammed up in such a way that between them lying cavities are eliminated and a largely continuous flow of material with homogeneous surface density arises. The excretion of foreign substances is carried out by Blow out by means of a compressed air nozzle.

Claims (14)

1. A method for detecting and separating foreign matter in fibre material, in particular in raw cotton, in which in a presentation channel (1) the fibre material is distributed and, in a loose form, pneumatically led past a sensor field whilst maintaining a continuous air stream and with this is continuously monitored by a sensor arrangement (2, 2') reacting to foreign matter, wherein on detecting foreign matter the impurified part quantity of fibre material is separated after the presentation channel from the conveying flow by blowing out by way of pressurised air, characterised in that the fibre material is led from above to below past the sensor field in the presentation channel on a presentation path which is inclined at 0° to 50° to the vertical.
2. A method according to claim 1, characterised in that from the width of the conveying flow only a certain segment in which the sensor arrangement recognised a foreign material is separated.
3. A method according to claim 1 or 2, characterised in that the conveying speed in the presentation channel is between 2 and 5 m/s.
4. A method according to claim 3, characterised in that the continuous monitoring at the sensor field is effected after a free presentation path of 0.5 to 1.2 m.
5. A method according to one of claims 1 to 4, characterised in that the flow in the presentation channel is completely or partly produced by blowing in air in front of the presentation channel.
6. A method according to one of claims 1 to 5 , characterised in that the flow in the presentation channel is completely or partly produced by maintaining a vacuum after the presentation channel.
7. A device for detecting and separating foreign matter in fibre material, in particular in raw cotton, with a presentation channel (1) which can be impinged by at least one sensor arrangement (2, 2') for detecting foreign matter and with pneumatic conveying means (4, 14) for generating a continuous air stream and guiding through the fibre material in a loose form through the presentation channel as well as with a separating device (17, 19), after the presentation channel, which can be controlled by the sensor arrangement comprising a nozzle socket (17) which is arranged for blowing out impurities from the conveying flow, characterised in that the presentation channel is inclined at an angle of 0° to 50° such that the fibre material may be led through it from above to below by the continuous air stream, wherein the fibre material can be supplied at the upper end of the presentation channel (1).
8. A device according to claim 7, characterised in that the nozzle socket (17) can be acted in a point-shaped manner in a manner such that only a certain segment may be separated from the width of the conveying flow.
9. A device according to one of claims 7 or 8, characterised in that the conveying means is a fan (4) whose pressure side is connected to the upper end of the presentation channel.
10. A device according to one of claims 7 to 9, characterised in that above the presentation channel there is arranged a distributing device (13) for the uniform metering of the fibre material into the presentation channel.
11. A device according to one of claims 7 to 10, characterised in that the sensor arrangement (2, 2') comprises at least an electronic line camera with colour sensor technology with which the whole width of the presentation channel may be acquired.
12. A device according to claim 11, characterised in that the sensor arrangement additionally comprises a sensor which functions in the ultraviolet or infrared region.
13. A device according to claim 11 or 12, characterised in that the impinging of the presentation channel by the sensor arrangement is effected via deflecting mirrors (8, 8').
14. A device according to one of claims 7 to 13, characterised in that it is constructed in a modular construction and that it comprises at least a supply module (23), a sensor module (24) and a separating module (25), wherein between these modules selectively further modules may be installed.

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