GB2461371A

GB2461371A - Apparatus for detection of foreign matter in fibre material

Info

Publication number: GB2461371A
Application number: GB0909456A
Authority: GB
Inventors: Guido Engels
Original assignee: Truetzschler GmbH and Co KG
Current assignee: Truetzschler GmbH and Co KG
Priority date: 2008-07-03
Filing date: 2009-06-01
Publication date: 2010-01-06
Anticipated expiration: 2029-06-01
Also published as: CH699123A2; ITMI20090928A1; GB0909456D0; GB2461371B; IT1394549B1; CH699123B1

Abstract

Apparatus in a spinning room preparation, ginning or the like installation for detection of foreign objects of plastics material in a stream of fibre material, especially cotton, comprises a detector 6311for foreign matter, preferably comprising a camera 13, which receives reflected ultraviolet light originating from source 43 and polarised light that has been transmitted through the stream of fibre material from source 18. Preferably neither the UV nor polarised light normally registers with camera 13. When the ultraviolet light contacts certain contaminants (e.g. dense plastics packaging straps) it may be converted by fluorescence into light visible to the camera 13. Also when the polarised light is passed through certain contaminants (e.g. polypropylene or polyethylene) its polarisation may be changed such that it becomes visible to the camera 13. Both types of light are preferably simultaneously registered by the camera. Contaminants having a similar colour to the bulk fibre may thus be detected. A further colour sensitive camera set-up 631may also be provided to detect contaminants having a colour different to that of the bulk fibre. The camera systems may be used to trigger a device to eject detected contaminants. The apparatus preferably comprises a channel through which fibre material is pneumatically conveyed.

Description

Apparatus in a spinning room prparation, ginning or like installation for the detection of foreign objects of plastics material, such as polypropylene or the like.

The invention relates to an apparatus in a spinning room preparation, ginning or like installation for the detection of foreign objects of plastics material, such as polypropylene, woven plastics and plastics sheeting or the like, in or amongst a flow of fibre material, for example, of cotton.

It is known, in such an installation, for foreign objects in or amongst the fibre material to be subjected to transillumination (transmitted light) by means of a source of polarised light that co-operates with a detector device (camera), with light and/or transparent foreign objects being transilluminated, and light from a further source acting on the flow of material.

One problem affecting the operation of optically functioning foreign fibre or foreign object separators in spinning room preparation machines for cotton or synthetic fibres is that these light-coloured or transparent plastics (such as, for example, packaging film or packaging fabric of polyethylene or polypropylene), owing to their low optical contrast, can be detected only inadequately, or not at all.

In the case of a known apparatus (EP 0 545 129 B) for the detection of polypropylene fibres in laps of silk, two images are compared. One image is produced by transilluminatirig with polarised light; the other is produced by transillurninating with white light. The material has to be present in the form of silk fibres oriented so that they are substantially parallel. The evaluating process requires two images to be compared. So that both images can be brought into register, the material is conveyed on a conveyor belt with movement synchronisation beneath both inspection points. This patent describes an apparatus that manages with just one camera. Nevertheless, two images have to be made, (one with polarised light and one with white light). For that purpose the lighting systems are switched on in succession so that both images can be taken by just one camera. To do this, however, the movement of the material has to be interrupted, the scanning operations taking place in succession and the silk fibre lap being advanced gradually. The apparatus is expensive in terms of construction. Particular inconveniences are the switching of the lighting system, the discontinuous material transport and the taking of two images. A further considerable disadvantage is that those packaging materials and plastics waste that are not identifiable using transillumiriated polarised light, for example, dense or thick scraps of packaging, cannot be detected.

Similarly, types of plastics that do not change the polarisation state of the transilluminated polarised light

are not detectable.

It is an aim of the invention to produce an apparatus of the kind described initially, which avoids or mitigates the said disadvantages, and which in particular permits effective detection of white and/or transparent pieces of plastics material in a simple manner in terms of construction.

The invention provides an apparatus in a textile fibre processing machine for the detection of foreign objects of plastics material in or amongst a flow of fibre material, comprising: a source of polarized light that co-operates with a detector device arranged for receiving light from the polarized light source that has been transmitted through the stream of fibre material for transillumination of the foreign objects and a source of ultraviolet light; wherein foreign objects in or amongst the fibre material are arranged to be illuminated by the source of ultraviolet light, and the source of ultraviolet light co-operates with the detector device, which is able to detect the transilluminated and illuminated foreign objects and differentiate them from the fibre material.

According to the invention, detection with polarised light is combined with detection with UV light, without basic components such as cameras, inspection chambers, glass channels or evaluating components having to be present in duplicate, and without the two detection methods interfering with one another. This arrangement concentrates the necessary components in minimal space and therefore saves on installation space. There is combined use of different wavelengths (visible light/UV light) and different polarisation states (polarised/unpolarised) Switching of the lighting system and the discontinuous transport of material is dispensed with, because instead of two images, just one is taken, which is illuminated with both light sources simultaneously. The fact that illumination and image acquisition can be effected simultaneously is another advantage, so that firstly no convergence of the two components occurs subsequently and there is no temporal resolution reduction resulting from double image acquisition. According to the invention, unpolarised illumination (without visible spectral components) (reflected light illumination) and polarised transillumination with visible light (transmitted light) are effected. With this combination an image is formed which can be captured by a camera without switching/flashing on the lighting system; thus the image also contains both effects through alteration of the polarisation state and also through fluorescence. In this way, even packaging materials and plastics waste that are not detectable with polarised light are detected in fibre materials. In the case of certain synthetic fibres, and also in the case of plastics materials manufactured with optical brighteners, the radiated ISV light is converted into visible wavelengths by a fluorescence effect. This can then be detected by normal camera systems. The camera is not sensitive to the radiated ISV light. Detection is effected only when, by fluorescence effects, the ISV light is converted into visible light. An extremely wide assortment of plastics foreign objects can therefore successfully be detected. In addition, dense or thick plastics scraps or sorts of plastics that do not alter the polarisation state of the polarised light passing through are also detected.

Advantageously, polarised light and the beam reflected as a consequence of UV irradiation are simultaneously recordable by the one further detector device: In some cases, when transilluminated with polarised light, the foreign objects are capable of altering the polarisation state of the light. In some cases, when illuminated with UV light, the foreign objects exhibit fluorescence effects.

Preferably the detector device comprises an evaluating device. In some embodiments, to cover a large working width several detector devices are provided in sections in parallel side by side. Advantageously, to reduce the installation space, the line of sight of the camera is deflectable by mirrors or prisms.

The camera may have a polarisation filter as analyser. The camera may have a filter that prevents the passage of UV light. Advantageously, a separation device for separating out the foreign objects, arranged downstream of the detection zone in the conveying direction, is connected to the evaluating device. In some cases, the foreign objects of plastics material rotate the polarisation vector of the polarised light. In some embodiments, the light may be linearly polarised. In other embodiments the light may be circularly polarised.

In yet further embodiments, the light may be elliptically polarised.

Advantageously, the light source for polarised light and the detector device are arranged on different sides of the fibre flocks (transmitted light arrangement).

Advantageously, the light source for UI! light and the detector device are arranged on the same side of the fibre flocks (reflected light arrangement) . Advantageously, a

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depolarisation is effected for detection. Advantageously, a reflection-suppressionis effected for detection.

Irr some cases, the foreign objects of plastics material alter the polarised light by anisotropic behaviour (such as double refraction) such that the light is rendered visible by the analyser of the detector device.

Advantageously, the fibre material is arranged in a channel of a transparent material, for example, glass or the like. The fibre material may be conveyed through a channel pneumatically.

The fibre material may be arranged on a conveyor belt. The fibre material may be arranged on a roller, e.g. detaching roller. Advantageously, the roller rotates rapidly.

Advantageously, the detector device is a line-scan camera, or a matrix camera.

The detector device may comprise light sensors.

Detection may take place in colour. Instead, detection may take place in black and white.

In some embodiments, a polariser is arranged between light source and fibre material. In some embodiments, a light source that emits polarised light is present. The polariser may be integrated on or within the light source.

In some embodiments, an analyser is arranged between the fibre material and the detector device. In some embodiments, a detector that also acts as analyser is present. The analyser may be integrated on or within the detector. In some embodiments, light-reflecting elements, for example mirrors, are arranged in the ray path. In some embodiments light-refracting elements for example prisms or lenses, are arranged in the ray path.

Advantageously, a device for removing (separating) foreign objects is arranged downstream of the evaluating device. Advantageously, the evaluating device and the removal device (separating device) are electrically connected with one another by a control or switching device. The apparatus may be arrangd, for example, downstream of a cleaning device, in a carding machine, downstream of a carding machine or downstream of a foreign fibre separator.

Advantageously anisotropies such as the double refractive effect of the foreign objects are used for detection. Advantageously, selectively absorbing behaviour (dichroism) of the foreign objects is used for detection. Advantageously, optically active behaviour (rotary dispersion) of the foreign objects is used for detection. Advantageously, the detector device is able to distinguish sheet-form from fibre-form foreign objects on the basis of its resolution.

In certain embodiments, the UV light source may be configured as a linear lighting system for illuminating the working width. In other embodiments, the UV light source may be configured from several individual light sources arranged close together for illumination of the working width. In yet other embodiments, the UI! light source comprises a single, for example, point-form, light source, which produces illumination of the working width via a projection device. Advantageously, the light of the UI! light source is bundled by reflectors or lenses onto the surface to be inspected. Advantageously, the UI! light source contains a filter which blocks all undesirable wavelengths and thus allows only UI! light to pass through.

In some embodiments, the channel is arranged vertically.

In other embodiments the channel may be arranged obliquely. The fibre material may be conveyed from top to bottom through the channel, or the fibre material may be conveyed from bottom to top through the channel.

The invention also includes embodiments in which the channel is arranged horizontally. Advantageously, the apparatus arranged downstream of an.opening roll is not arranged directly in the delivery region of the opening roll.

The present invention also provides an apparatus in a spinning preparation, ginning or like installation for the detection of foreign objections of plastics material, such as polypropylene, woven plastics and plastics sheeting or the like, in or amongst a flow of fibre material, for example, of cotton, in which foreign objects in or amongst the fibre material are arranged to be transilliminated (transmitted light) by means of a source of polarised light that co-operates with a detector device (camera), with light and/or transparent foreign objects being transilluminated, and light from a further source acts on the flow of fibre material, in which foreign objects in or amongst the fibre material are arranged to be illuminated (reflected light) by means of a source of ultraviolet light and the source of ultraviolet light co-operates with the detector device (camera) which is able to detect the transilluminated and illuminated foreign objects and differentiate them from the fibre material.

Certain illustrative embodiments of the invention will be explained hereafter with reference to the accompanying drawings, in which: Fig. 1 shows a first embodiment apparatus according to the invention on a foreign object detection and separation device with horizontal transport duct, Fig. 2 shows a second embodiment according to the invention on a foreign object detection and separation device with lighting systems-for polarised incident light and UV reflected light, vertical transport channel and straight line of sight of the camera, Fig. 3 shows a third embodiment, in some respects corresponding to the embodiment of Fig. 2, but with a deflected line of sight of the camera, Fig. 4 shows a construction with two detection devices,

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Fig. 5 shows diagrammatically a side view of an apparatus with a glass channel and lighting equipment for polarised incident light, Fig. 6 is a plan view of a blow-out system with a plurality of blast nozzles arranged across the width; Fig.7 is a block diagram of an electronic control and regulating device, to which two sensor systems and two blow-out systems are connected; Fig. 8 shows a apparatus according to the invention downstream of a four roll cleaning machine; Fig. 9 shows an apparatus according to the invention downstream of a one roll cleaning machine; and Fig. 10 shows an apparatus according to the invention on a foreign object detection and separation device with vertical transport channel.

Referring to Fig. 1, in an apparatus for detecting and separating foreign objects, e.g. a foreign part separator SECUROMAT SP-FP made by Trützschler GmbH & Co. KG of Monchengladbach, Germany, the upper inlet opening of a feed chute 1 has associated with it an arrangement for the pneumatic supply of a fibre-air flow A, which comprises a fibre material transport fan (not shown), a stationary air-permeable surface 2 for separation (ejection) of the fibre material B from air C with air extraction, and an air flow guide means 3 with movable elements; the fibre material present in the air flow is guided reversibly backwards and forwards transversely over the air-permeable surface 2 and, following impact, the fibre material falls substantially as a result of gravity from the air-permeable surface 2 and enters the feed chute 1 downwards. The slow-speed rollers 4a, 4b have a dual function: they serve as take-off rolls for the fibre material B out of the feed chute 1 and at the same time as feed rolls for supplying the fibre material B to a high-speed opening roll 5. The solid arrows represent fibre material, the empty arrows represent air and the half-filled arrows represent an air current with fibres.

An optical sensor system 6, for example, a line-scan camera 6 (CCD camera) with an electronic evaluating device for the detection of foreign objects, especially with brightness and/or colour differences, is associated with the whole length of the surface of the opening roll 5.

The sensor system 6 is connected by way of an electronic control and regulating device 35 (see Fig.7) to an arrangement 7 for separating the foreign objects (see Fig. 6) . The arrangement 7 is capable of generating a short blast air current, which travels towards the clothed face surface and creates a suction air flow, which detaches the foreign objects together with a few fibres from the clothed face and removes them into a channel 10.

The optical sensor system 6 with the camera, for example, a colour line-scan camera, isarranged obliquely above the opening roll 5 close to the outer wall of the feed chute 1. This produces a compact, space-saving construction. The colour line-scan camera 6 is directed towards the clothing of the opening roll 5 and is able to detect coloured foreign objects, for example, red fibres, in the fibre material. The camera 6 covers the entire region across the width of the opening roll 5, e.g. 1600 mm. The opening roll S rotates anticlockwise in the direction of the curved arrow. Downstream of the optical sensor system 6 in the direction of rotation is the arrangement 7 for producing a blast air current, the nozzles of which are oriented towards the clothed face of

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the opening roll 6, so that a short, sudden jet of air flows tangentially in relation to the clothed face. The sensor system 6 is connected by way of an evaluating device and an electronic control and regulating device to the arrangement 7, with which there is associated a valve control means 8. When the camera 6 has detected a foreign object in the fibre material on the clothed surface using comparative and desired values, using the valve control means 8 a short air blast is expelled at high speed in relation to the clothing and tears the foreign object with a few fibres out of the fibre covering on the clothing by a suction air current1 and subsequently carries them away through a channel 10 under suction.

A blast air current flows through a channel approximately tangentially to the opening roll 5, detaches the fibre covering (good fibres) from the clothing and flows away as a fibre-air flow D through a fibre transport duct 11 to the glass channel 17.

An embodiment of the apparatus 12 according to the invention is associated with the pneumatic fibre transport duct 11. The apparatus 12 is suitable for detecting foreign objects of any kind, for example, pieces of cloth, tapes, string, pieces of sheeting etc, in the fibre material. According to an advantageous construction, the apparatus 12 is used to detect foreign parts of plastics material, such as polypropylene bands, fabric and sheeting or the like in or amongst *fibretufts, for example, of cotton and/or synthetic fibres. The plastics materials are light-coloured, white or transparent.

In the case of the apparatus 12 for detecting foreign objects, the fibre material is transported in an air flow (fibre-air flow]J) through a pneumatic fibre transport duct 11, which is connected to a suction source (not shown). As the optical sensor system, two cameras 13a, 13b, for example, diode array cameras with polarisation filters, are arranged in a housing 14 above the fibre transport duct 11 across the machine width, whióh is, for example, 1600 mm. Beneath the cameras 13a, 13b (only camera 13a is shown), the wall surfaces of the fibre transport duct 11 have two transparent regions in the form of two parallel and opposite glass panes 17a, 17b (glass windows), which form a glass channel 17. As a source of polarised light, lighting equipment 18 is provided beneath * the fibre transport duct 11. As a source of ultraviolet (IJV) light, further lighting equipment 43 is provided above the fibre transport duct 11. Downstream of the glass channel 17, a blow-out device 19 for separation of the foreign objects 34 detected by the apparatus 12 is associated withthe fibre transport duct 11. Downstream of the blow-out device 19, the fibre-air flow D is sucked through the fibre transport duct 11 and fed onwards for further processing.

In operation, the camera 13 detects the fibre-air flow D through the glass pane 17a. Here, *the glass pane 17a projects into the fibre-air flow D in such a way that the fibre-air flow D meets the glass pane 17a and flows along and in pressure-applying contact with the glass pane l7a. Through the movement of the fibre-air flow D, on the one hand largely or completely unwanted deposits on the glass pane 17a are avoided and, if slight deposits do occur, they are wiped off the inner surface of the glass * pane 17a by the fibre-air flow D and carried away through the channel 11. The fibre-air flow D has a similar effect on the inner surface of the glass pane 17b.

If unwanted foreign objects 34 are detected in the fibre-air flow D by the apparatus 12, the blow-out device 19 is activated, and blows the foreign objects 34 into a suction channel 20.

In the embodiment of Fig. 2, the light of the light source 18 (here a fluorescent tube) is converted via a polarisation filter 28 into polarised light and passes through a glass pane 17a into the inspection region. This inspection region is, in this example, formed by a chute of rectangular cross-section, by which the fibre material -is guided past the inspection point. The direction in which the material is conveyed is here from top to bottom.

(The embodiment according to Figures 2 and 3 is applicable in an analogous manner in the case of the embodiment according to Fig. 1 with a horizontal channel 11). The glass panes 17a, 17b are inclined slightly to the flow of material D so that the surfaces are self-cleaning. *The polarised light passes through the inspection region via a second glass pane 17b finally to a camera 13, which is also equipped with a polarisation filter 42 as analyser.

This blocks all incident, unaltered polarised light of the light source 18, so that altogether a dark image is produced. Further, the inspection chamber is illuminated by a light source 43 that radiates ultraviolet light (four UV fluorescent tubes form the light source here). This light source 43 does not radiate any wavelength components in the visible range, so that the camera 13, which is sensitive only to the visible range of the optical spectrum, is not triggered. This is achieved by suitable optical filters in the light source itself (known as black light) or by additional filters to be placed in front of the light source. If necessary, the camera 13 or the sensor of the camera 13 must be fitted with a further filter 44, which blocks TJV light, so that the camera is not sensitive in the UI! wavelength range.

Since the camera 13 with the analyser 42 is sensitive neither to polarised light nor to UI! light, it will in the * normal case register a dark image. If there is now fibre material 40 in the inspection chamber, then the polarised light shines through it and it is illuminated by the UI! light. The polarised light is not altered by the fibre material 40, and the dark image persists. The UI! light is also not altered by the fibre material 40. UV light reflected back to the camera 13 is not registered, as the camera 13 is not sensitive in this wavelength range. The dark image persists. If, however, transilluminable foreign objects 34 (for example, packaging bands of polypropylene or polyethylene sheeting) are present in the inspection chamber, then these alter the polarisation state of the polarised light. This light is now able to pass through the analyser 42 of the camera 13 and thus ensures the camera is triggered, which is registered by the evaluation * unit 38 connected to the camera and is used, for example, by a downstream separation unit (blow-out device 19, see Figures land 5) to discharge these foreign objects 34 from the channel 41. In the case of foreign objects not transilluminable (for example, dense packaging scraps of plastics material), no polarised light gets through the foreign object to the camera 13. Instead, the radiated UV light is converted by a fluorescence effect, which may be observed in the case of many packaging materials that are provided with optical brighteners, into light of visible wavelengths. This light is now able o pass through the UV blocking filter 44 and thus triggers the camera 13, which in turn is registered by the connected evaluation unit 38.

Fig. 3 shows an arrangement which is similar to that of Fig. 2 except that the line of sight 45 of the camera is deflected by way of a mirror 46 to reduce the installation space required.

Where large channel widths are concerned, it may be advantageous to distribute several detection apparatuses according to Fig. 2 across the working width, so that each is responsible for just a section of the channel 41. Here too, however, both detection processes can be achieved with just one detector and one evaluation unit per section.

Fig. 4 shows, from a viewing direction with the material conveying direction perpendicular to the plane of the paper, an embodiment in which several detection apparatuses 471, 4711 are arranged side by side in order to cover the large working width. Each apparatus 47', 47" is separately responsible again both for detection with polarised light and for detection with UV light with just one sensor system 13 each. In this example, the lighting systems 18 and 43 are subdivided into sections, but are achieved by one continuous component. Similarly, the

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evaluation units assigned to the individual sections can further be combined to form one evaluation unit 38'.

In the illustrative arrangement shown in Fig. 5, a holding device 21 is provided, which comprises four extruded aluminium hollow profiles 21a, 2lb, 21c, 21d (holding profiles), which are arranged parallel to one another in the longitudinal direction -across the machine width -and are each fixed by their front faces to the two framework walls (not shown) of the machine. As an example, a fixing bolt 22 is shown on the extruded profile 21a. The internal flat faces 21', 21", 21" and 21V form part of the inner circumferential surface of the fibre transport duct 11 and the duct 41 respectively. The faces 21' and 21" on the one hand and the faces 21" and 2l on the other hand are arranged parallel to one another. The facing lateral regions of the extruded profiles 21a to 21d each have a concave face in the form of a portion of a cylinder shell. A housing 23, which is rotatable in the direction of the arrows G, H about its longitudinal axis M, is located between and in contact with the four faces in the form of a portion of a cylinder surface. The housing 23 comprises a support element 24 of two extruded aluminium hollow profiles 24a, 24b (support profiles), which in cross-section are each constructed as a portion of a cylinder. The external contour of the housing 23 is circular. The convexly rounded external faces of the support profiles 24a, 24b engage with the faces of the holding profiles 21a, 21b and 21c, 21d respectively that are concavely rounded and in the form of a portion of a cylinder shell. Flat glass panes 17a, 17b are arranged in the flat chord faces of the support profiles 24a, 24b respectively, the chord faces and the external faces of the glass panes l7a, l7b aligning with one another. The two opposing faces each formed in this way by chord faces and glass panes l7a, 17b respectively form part of the fibre transport channel 11 and the channel 41, which narrows in the direction of the fibre-air flow D. The two opposing faces of the glass panes 17a, 17b form a glass

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channel 17, which likewise tapers conically in the directio of the fibre-air flow D. The face formed by the faces 21', 21" forms an acute and shallow angle a' with the face of the support element 24a formed by the chord face and glass pane 17a, and the face formed by the faces 21111, 2l" forms an acute and shallow angle a" with the face of the support profile 24b formed by the chord face arid glass pane 17b. The conically converging faces of the two opposing faces, each comprising a chord face and a respective glass pane 17a, 17b, form an angle 3.

Lighting equipment 18 (f or polarised transmitted light) is present beneath the housing 23 for the glass channel 17, having a housing 25 that is mounted in guide grooves on the holding profiles 2lc, 21d, extending across the width of the machine. Inside the housing 25, two fluorescent tubes 26, 27, for example, neon tubes, are arranged parallel side by side and extend with their longitudinal axes across the working width of the machine.

The housing 25 is an aluminium extruded hollow profile with cooling fins 25a. Elongate glass panes 28a, 28b with polarisation filters are mounted in the top face 25b of the housing 25 facing the housing 23 for the glass channel 17. The polarisation filters (not shown) of the cameras 13a, 13b on the one hand and the polarisation filters (not shown) of the glass panes 28a, 28b on the other hand are arranged at a right angle to one another.

The lighting equipment 43 (for UV reflected light illumination) is arranged above the housing 23 for the glass channel 17 (see Fig. 1) The illustrative construction in Fig. 5 was explained using the example of the horizontal transport channel 11 (Fig.1). The construction may be analogous for the vertical channel 41 (Figures 2 and 3).

In an illustrative arrangement shown in Fig. 6, the blow-out device 19 comprises a plurality of blast nozzles 30a to 30n, each associated with a respective valve 3la to 3ln. The blast nozzles 30a to 30n are connected by way of the valves 3la to 3ln to a common compressed air line 32, which is connected to a source of compressed air 33. The reference numeral 11 denotes the fibre transport duct, which has inlet openings for the blast nozzles 30a to 30n.

The outlet opening for the currents of blast air into the channel 20 is shown in Fig. 1. The valves 31a to 3m are selectively controlled by a valve control means, for example, in the presence of a foreign object 34 the valve 31d is briefly opened so that a sudden current of air leaves the nozzle 30d at high speed, for example, 15 to 25 m/sec, and blows the foreign object 34 into the channel 20 (see. Fig. 1) In the illustrative arrangement of Fig. 7, the camera 6, an image evaluating device 36 and a valve control means 37 for the valves of the blow-out device 7 are connected to an electronic control and regulating device 35. In addition, the cameras 13a, 13b, an image evaluating device 38 and the valve control means 39 for the valves 3la to 3m of the blow-out device 19 are connected to the electronic control and regulating device 35.

With reference to Fig. 8, an apparatus according to the invention, as shown in Fig. 3, is mounted downstream of a cleaning machine 50, for example, a CL-C4 cleaning machine made by TrQtzschler GmbH & Co. KG. The fibre material is removed from the last high-speed clothed roller 514 by an air current E (air doffing) and passes as a fibre-air flow D into a channel 52, which is of approximately U-shaped construction, one arm of which merges upwards into a vertical channel 53. The fibre-air mixture ID f lows through the channel 53 from bottom to top.

The apparatus according to the invention, as shown in Fig. 3, is associated with the duct 53. Following the detection apparatus according to the. invention there is a blow-out device 19 (for example, of analogous construction to that shown in Fig. 1). The fibre-air mixture freed from foreign objects is subsequently fed onwards for further processing. The apparatus according to the invention (camera 13, lighting equipment 18, 43, tilted mirror 46) is not arranged directly in the delivery region of the openingroll 514.

In the arrangement of Fig. 9, an apparatus according to the invention, as shown in Fig. 3, is mounted downstream of a cleaning machine 54, for example, a CL-Cl cleaning machine made byTrUtzschler GmbH & Co. KG. The fibre material is removed from the high-speed clothed roller 55 by the air current E (air doffing) and passes as a fibre-air flow D into an obliquely arranged channel 56, which merges upwards via a curved region into a vertical channel 53. The fibre-air mixture D flows through the channel 56 and the channel 53 from bottom to top. The apparatus according to the invention, which is as shown in Fig. 3, is associated with the channel 53, analogous to Fig. 8. Following the detection apparatus according to the invention there is a blow-out device 19 (see Fig. 8), and the fibre material G freed from foreign objects is subsequently fed onwards for further processing. The apparatus according to the invention (camera 13, lighting equipment 18, 43, tilted mirror 46) is arranged not directly in the delivery region of the opening roll 55.

In the apparatus of Fig. 10, a vertically arranged channel 57 is provided in a housing 58. The arrangement of Fig. 10 provides for conveying of the fibre material from top to bottom through a channel in which it is monitored.

The half-f ilied arrow designated by reference letter I represents the downward travel of the fibres conveyed in an air current. The monitoring of fibres in a channel, flowing from top to bottom, has been found to be advantageous.

The parallel side walls 57', 57" located opposite one another are constructed, at least in part, as transparent panes (see Fig. 2), forming a transparent channel 62.

Illumination means are associated with the outsides of both side walls 57', 57".

A first detector device comprises two CCD cameras 59', 59" (line-scan cameras), which are indirectly applied to the glass channel 62 by way of two tilted mirrors 60' and 60", respectively, arranged at an angle. The optical planes are arranged slightly offset from one another. On that side of the channel 57 which is located opposite the camera 591 there is arranged a lighting system 61', and on that side of the channel 57 which is located opposite the camera 59" there is arranged a lighting system 61". By that means, the material in the glass channel 62 is detected by the two cameras 59', 59" from two sides.

The housing 58' containing the glass channel 62, the cameras 59' 5911 the tilted mirrors 60', GO" and the lighting systems 61', 61" form a first detection module 63', where, especially, coloured foreign material in and between the cotton is detected.

Below the first detection module 63' there is a second.

detection module 63". The cross-sections of the channel 57 are the same.

A second detector device comprises a COD camera 13, which is indirectly applied to the glass channel 64 by way of a tilted mirror 46 arranged at an angle. On that side of the channel 57 which is located opposite the camera 13 there is arranged a lighting system 18 having polarisation filters (see Fig. 2), and on that side of the channel 57 which faces the camera 13 there is arranged a lighting system 43 for UV light. The polarised light (transmitted light) and the reflected light due to UV irradiation (incident light) are jointly captured by the one CCD camera 13. Light -transmitted light and incident light -is applied to the material in the glass channel 64 from two sides.

The housing 58" containing the glass channel 64, the camera 13, the tilted mirror 46 and the lighting systems 18, 43 form a second detection module 63", where, especially, light-coloured or transparent plastics in or between cotton are detected.

Below the second detection module 63" there is provided a separation module 65. The separation module 65 in the housing 58" comprises a blow-out device 19 having a row of nozzles, which is associated with a side wall of the channel 57. Associated with that side wall of the channel 57 which is located opposite the row of nozzles (see Fig. 7) is a collection container 20, which is under suction, for the impurities blown out from the conveyed stream.

The apparatus according to the invention was explained using the example of a cleaner 50, 54 in spinning room preparation. It may be used similarly in the ginning process on a cotton gin.

Claims

SClaims 1. An apparatus in a textile fibre processing machine for the detection of foreign objects of plastics material in or amongst a flow of fibre material, comprising: a source of polarized light that co-operates with a detector device arranged for receiving light from the polarized light source that has been transmitted through the stream of fibre material for transillumination of the foreign objects; and a source of ultraviolet light; wherein foreign objects in or amongst the fibre material are arranged to be' illuminated by the source of ultraviolet light, and the source of ultraviolet light co-operates with the detector device, which is able to detect the transilluminated and illuminated foreign objects and differentiate them from the fibre material.
2. An apparatus according to claim 1, in which the polarised light and the light reflected as a consequence of uv illumination can be jointly registered by the one detector device.
3. An apparatus according to claim 1 or claim 2, in which the polarised light and the beam reflected as a consequence of UV illumination can be simultaneously registered by the one detector device.
4. An apparatus according to any one of claims 1 to 3, in which, when transilluminated with polarised light, the foreign objects are capable of altering the polarisation state of the light.
5. An apparatus according to any one of claims 1 to 4, in which, when illuminated with UV light, the foreign objects exhibit fluorescence effects.
6. An apparatus according to any one of claims 1 to 5, in which the detector device comprises an evaluating device.
7. An apparatus according to any one of claims 1 to 6, in which the detector device comprises a plurality of detector units provided in sections in parallel side by side for covering the working width of the channel.
8. An apparatus according to any one of claims 1 to 7, in which, to reduce the installation space, the line of sight of the camera is deflectable by mirrors or prisms.
9. An apparatus according to any one of claims 1 to 8, in which, detector device comprises a camera having a polarisation filter as analyser.
10. An apparatus according to any one of claims 1 to 9, in which the detector device comprises a camera having a filter that prevents the passage of UV light.
11. An apparatus according to any one of claims 1 to 10, in which a separation device for separating out the foreign objects, arranged downstream of the detection zone in the conveying direction, is connected to an evaluating device of the detector device.
12. An apparatus according to any one of claims 1 to 11, in which the foreign objects of plastics material rotate the polarisation vector of the polarised light.
13. An apparatus according to any one of claims 1 to 12, in which the light is linearly polarised.
14. An apparatus according to any one of claims 1 to 12, in which the light is circularly polarised.
15. An apparatus according to any one of claims 1 to 12, in which the light is elliptically polarised.
16. An apparatus according to any one of claims 1 to 15, in which the light source for polarised light and the detector device are arranged on different sides of the fibre flocks.
17. An apparatus according to any one of claims 1 to 16, in which the light source for tJV light and the detector device are arranged on the same side of the fibre flocks.
18. An apparatus according to any one of claims 1 to 17, in which a depolarisation is effected for detection.S
19. An apparatus according to any one of claims 1 to 18, in which a reflection-suppression is effected for detection.
20. An apparatus according to any one of claims 1 to 19, in which the foreign objects of plastics material alter the polarised light by anisotropic behaviour such that the light is rendered visible by the analyser of the detector device.
21. An apparatus according to any one of claims 1 to 20, in which, in the region in which the detection is to be carried out, the fibre material is arranged in a channel of a transparent material.
22. An apparatus according to any one of claims 1 to 20, in which, in the region in which the detection is to be carried out, the fibre material is conveyed through a channel pneumatically..
23. An apparatus according to any one of claims 1 to 20, in which, in the region in which the detection is to be carried out, the fibre material is arranged on a conveyor belt.
24. An apparatus according to any one of claims 1 to 20, in which, in the region in which the detection is to be carried out, the fibre material is arranged on a roller.
25. An apparatus according to claim 24, in which the roller rotates rapidly.
26. An apparatus according to any one of claims 1 to 25, in which the detector device comprises a line-scan camera.
27. An apparatus according to any one of claims 1 to 26, in which the detector device comprises a matrix camera.
28. An apparatus according to any one of claims 1 to 27, in which the detector device comprises light sensors.
29. An apparatus according to any one of claims 1 to 28, in which detection takes place in colour.
30. An apparatus according to any one of claims 1 to 29, in which detection takes place in black and white.S
31. An apparatus according to any one of claims 1 to 30, in which a polariser is arranged between light source and fibre material for generating polarised light for transillurninat ion.
32. An apparatus according to any one of claims 1 to 31, in which a light source that emits polarised light is present.
33. An apparatus according to claim 31 or claim 32, in which a polariser is integrated on or within the light source.
34. An apparatus according to any one of claims 1 to 33, in which an analyser is arranged between the fibre material and the detector device.
35. An apparatus according to any one of claims 1 to 34, in which a detector that also acts as analyser is present.
36. An apparatus according to any one of claims 1 to 35, in which the analyser is integrated on or within the detector.
37. An apparatus according to any one of claims 1 to 36, in which light-reflecting elements are arranged in the ray path.
38. An apparatus according to claim 37, in which the light-reflecting elements are mirrors.
39. An apparatus according to any one of claims 1 to 37, in which light-refracting elements are arranged in the ray path.
40. An apparatus according to any one of claims 1 to 39, in which the light-refracting elements are prisms.
41. An apparatus according to any one of claims 1 to 40, in which the light-refracting elements are lenses.
42. An apparatus according to any one of claims 1 to 41, in which a deyice for removing foreign objects is arranged downstream of the detector device.
43. An apparatus according to claim 42, in which an evaluating device for the detector device and the removal device are electrically connected with one another by a control or switching device.S
44. An apparatus according to any one of claims 1 to 43, in which the apparatus is arranged downstream of a cleaning device.
45. An apparatus according to any one of claims 1 to 43, in which the apparatus is arranged in a carding machine.
46. An apparatus according to any one of claims 1 to 43, in which the apparatus is arranged downstream of a carding machine.
47. An apparatus according to any one of claims 1 to 46, in which the apparatus is arranged downstream of a foreign fibre separator.
48. An apparatus according to any one of claims 1 to 4.7, in which anisotropies of the foreign objects are used for detection.
49. An apparatus according to any one of claims 1 to 48, in which selectively absorbing behaviour of the foreign objects is used for detection.
50. An apparatus according to any one of claims 1 to 49, in which optically active behaviour of the foreign objects is used for detection.
51. An apparatus according to any one of claims 1 to 50, in which the detector device is able to distinguish sheet-form from fibre-form foreign objects on the basis of its resolution.
52. An apparatus according to any one of claims 1 to 51, in which the UV light source is configured as a linear lighting system for illuminating the working width.
53. An apparatus according to any one of claims 1 to 51, in which the liv light source is configured from several individual light sources arranged close together for illumination of the working width.
54. An apparatus according to any one of claims 1 to 53, in which the liv light source comprises a single, light source, which produces illumination of the working width via a projection device.
55. An apparatus according to any one of claims 1 to 54, in which the light of the UV light source is bundled by reflectors or lenses onto the surface to be inspected.S
56. An apparatus according to any one of claims 1 to 55, in which the UV light source contains a filter which blocks all undesirable wavelengths and thus allows only Liv light to pass through.
57. An apparatus according to any one of claims 1 to 56, in which the channel is arranged vertically.
58. An apparatus according to any one of claims 1 to 56, in which the channel is arranged obliquely.
59. An apparatus according to claim 57 or claim 58, in which the fibre material is conveyed from top to bottom through the channel.
60. An apparatus according to claim 57 or claim 58, in which the fibre material is conveyed from bottom to top through the channel.
61. An apparatus according to any one of claims 1 to 56, in which the channel is arranged horizontally.
62. An apparatus according to any one of claims 1 to 61, in which the apparatus arranged downstream of an opening roll is not arranged directly in the delivery region of' the opening roll.
63. A detection arrangement for use in a method for detecting foreign matter flow of fibre material, the detection arrangement comprising: a detector device comprising at least one camera a source for generating polarised light; a source for generating ultraviolet light; and means defining a path for passage of the flow of fibre material through the detection arrangement; wherein the at least one camera is positioned for receiving light from the polarised light source that has been transmitted through the flow of fibre material and light reflected from the flow of fibre material as a consequence of the UV light illumination.
64. A method for detecting foreign matter in or between fibre material, comprising illuminating a flow of fibre material with UV light and illuminating the flow of fibre material with polarised light, positioning a detector device'in the path of the polarised light that has passed through the flow of fibre material and UI! light that has been reflected from the fibre material, and detecting modifications in the light that have arisen in consequence of interaction thereof with foreign matter in the flow of fibre material.