|Title of Invention||
A PROCESS AND AN APPARATUS FOR PRODUCING YARN FROM FIBERS
|Abstract||The present invention relates to a process and an apparatus for producing yarn from fibers which may contain extraneous material, the improvement comprising forming the material being processed into a linearly moving fibrous band at a stage in the production process before the formation of yarn, and sensing the surface of the linearly moving fibr'"'us band at that stage in the process to determine whether the sensed portion of the fibrous band contains extraneous substances and extraneous fibers.|
PROCESS AND DEVICE FOR DETECTING EXTRANEOUS SUBSTANCES AND EXTRANEOUS FIBRES IN A FIBROUS COMPOSITE
The invention relates to a process and a device for detecting extraneous substances and extraneous fibres in a fibrous composite.
From EP 0 744 478, for example, a device for extraneous fibre detection on an opening machine is known, with the aid of which fibres in a fibre-opening line are examined for deviations in colour by means of colour sensors. This takes place in the region of an opening roller, where the fibres rest on or against the opening roller in a very loose composite.
From WO 93/13407 a process for identifying extraneous fibres in a moving yarn is known, in which light is thrown onto a stationary point on the yarn and a number of sensors pick up the reflected light and the transmitted light.
From EP 0 679 599 a fibre band monitoring arrangement is known, which has the function of detecting a break in the fibre band and in which the transport movement of the band is detected by a sensor.
From :^B 1 211 463 a test apparatus is known, with the aid of it is possible to identify, in the laboratory, extraheous rigors in a band made of fibres. In this apparatus, the band is pressed flat and fanned out so that it subsequently forms only a comparatively thin layer, which can be transilluminatedl
The known processes and devices each have specific disadvantages, depending upon their construction and the place, in the production line at which they act. If the
identification or detection or the extraneous roes anta extraneous substances takes place in the yarn, the only-possibilities available are either to cut. out portions of yarn contaminated by extraneous fibres or extraneous substances, something which interrupts production of the yarn and results in splices in the yarn when the latter put together, or else to leave the contaminants in the yarn. Considerable lengths of yarn may pet affected, depending. upon the nature of the contamination. If the identification or detection takes place too early in production, for example in the opening machine, it is often possible to remove contaminants only by also centrifuging out fairly large quantities of the non-contaminated fibrous composite with them. In this connection, however, it is also possible for the contamination to occur in such an attenuated mariner that it may possibly not be identified by sensors at all, because set threshold values are not reached by the sensor signals. If it is desired to identify contaminants still earlier, for example when the fibroijis material occurs in flocks, contaminants may popinjay not be identified at all because they are concealed inside the flock. If contaminants and extraneous fibre are ascertained in known manner in the band, the latter must be centrifuged out of the current production and is altered to such an extent, for measurement or examination purposes, that it can be said to be destroyed.
The invention, as characterised in the claims, therefore achieves the object of detecting extraneous substances and extraneous fibres in a fibrous composite during current production, on the one hand when they may make their presence felt in a disruptive manner because of their concentrated nature, and on the other hand, when they are not already processed in a finished product.
This is achieved through the fact that the detection of extraneous fibres and extraneous substances in the fibrous
composite takes place when the latter forms a fibre band during production. Depending upon the nature of the extraneous substances, detection may take place through coactively or optically operating sensors, the signals from which are evaluated in an appropriate manner. That means, for example, that the signal from a capacitive sensor is not examined for deviations such as are brought about by fluctuations in the weight of the band, but for deviations such as are typical, for example, of extraneous fibres, extraneous substances, etc. In the case of optical sensors, the signals are evaluated in such a way that, for example, deviations in colour or in surface constitution are filtered out or isolated and thus indicate an extraneous substance. in the case of optical sense’s, the operation should preferably be carried out with incident light, and the reflection of the light should be measured. Different colours can be made visible in the sensor signals by filtering the light received. It is thus possible to differentiate between admissible colour signals and inadmissible ones which indicate, for example, extraneous fibres. The place of detection of the extraneous fibres and extraneous substances preferably lies between the exit from a carder, section or the like and the entry into a can. For the detection 6f the extraneous fibres, the band is legit in its shape, that is to say is not changed. If a contestant is identified, there are various possible ways of reacting to it. A first possibility consists in stopping production or the processing device. Other possibilities consist in marking the carrier of the band or just that can which contained the contaminated band, or in marking the band itself in order to remove it later. The contaminants can also be cut out or removed in some other way, something which causes an interruption in the band. Alternatively, an alarm can be triggered.
The advantages achieved through the invention can be seen, in particular, in the fact that the fibrous composite, that
is to say the cotton, for example, is not fanned out in a broad manner at the place of detection, a fact which reduces expenditure for detection purposes and does not destroy the test piece. This also means that the area to be subjected to detection, as a whole, by the sensors is small, a fact which limits the expenditure on sensors. Special deformation of the ami is not necessary. If the contaminants occur in a heaped-up manner, it is almost certain jag they will occur on the surface of the band and will thereby be reliably detected. Here, it is still possible to remove the contaminants without stopping the entire production process, since it is mostly only individual cans in a whole group that are affected. With the aid of the invention, concentrated vitiations or contaminations of large area are detected, which appear on the surface of the band.
The invention will be explained in greater detail below with the aid of an example and with reference to the accompanying drawings, in which:
figure 1 shows part of a carder, represented diagrammatically,
figure 2 shows a sensor for band material,
figure 3 shows a band with a typical contaminant,
figure 4 shows a typical signal pattern, and
figure, 5 shows part of a section, represented diagrammatically.
Figure 1 shows, represented in simplified form, a carder 1 which processes a fibrous composite 2, in a manner which is known per se and is therefore not represented in greater detail here, through the fact that a band 4 with an
essentially round or oval cross-section is produced from a laminar non-woven 3. The band 4 is deposited, in a manner which is likewise known, in a can 5 which, has to be periodically replaced when it has been filled. Disposed along the band 4, between a delivery point of the carder 1 and the can 5, is a sensor 6 which is connected, via a line or a bus 7, to a computer 8. The latter is preferably further connected to a marking device 15 via an output 14. However, ^^he said output 14 could likewise terminate in an alarm device.
Figure 2 shows a possible design for a sensor 6 for the band 4. The said sensor may consist of two parts 9 and 10 which are of identical composition and are mounted so as to be tiltable in relation to one another, as is indicated by an arrow 11. The two parts 9 and 10 each have a measuring chamber 12, 13 which is open towards one side, the two measuring chambers being disposed in such a way in relation to one another that the band 4 is able to traverse the two parts 9 and 10 of the sensor by traversing the two measuring chambers 12, 13. The disposition of the measuring chambers 12, 13 is preferably selected in such a way that the band 4 is enclosed, if possible over its entire periphery, by the sensor 6. As can be seen, in particular, from the measuring chamber 12, the latter has three boundary faces 12a, 12b and 12c, and at least one, preferably two, of these boundary faces have a measuring system which terminates, for example, in a window 20, 21, Each part 9, 10 of the sensor has a measuring system such as is known, for example, from patent applications WO 93/13407 or EP 0 401 600. Under these circumstances, parts of the measuring systems which are associated with oppositely located windows may also combine to form a measuring system, that is to say, for example, parts which are associated with the window 20 and with a non-visible window in the boundary face 12c. For the purpose of inserting the band 4, it is possible for at least one part
Before full operation of the carder starts, feeder band is fed out of the carder and into the sensor S, in which the part 10, for example, is pivoted away as indicated by the arrow |ll. When the band 4 is fed in, the part 10 can be pivoted Jack again and full operation of the carder can be started. The sensor 6 then detects, for example optically, deviations in colour or intensity or capacitive deviations in the dielectric and converts these into an electrical signal 2^ which is analysed in the computer 8. Stored in the said computer 8 are algorithms and threshold or comparison values 28, 32 which make it possible to identify extraneous fibres or extraneous substances from the signal in the line 7. If these are identified, a signal which triggers an alarm or the stopping of the installation is issued via the output 14.
Alternatively, however, the output 14 can also be connected to a marking device 15 which, activated by the said output, marks the relevant can 5 as the carrier of the band. A marking device 15 of this kind may, for example, be constructed as a paint-spraying arrangement which marks the external face of the can with paint. However, it is also conceivable, in automatic can-changing installations, to trigger a change of can prematurely by the signal in the output 14 in order to deposit contaminated points in special cans. However, a marking device 16 could also be fitted directly to the sensor 6 in order to identify the position of a contaminant on the band 4 itself in a conspicuous manner, so that the said band can be treated later by hand (figure 1).
Particularly when it has an optical measuring system, the sensor 6 detects changes in the colour or structure of the surface of the band. In order to detect vitiations in the band, especially when they octur over a large area or in such a way as to be concentrated in so-called "swarms", the measuring system should have a resolution which tends to be
small fn respect of the location, that is to say so that individual extraneous fibres are not identified at all. The resolution is also selected in such away that vitiatjLons or extraneous fibres which are present in the interior of the band are hot identified at all, even if the should show through to the surface. In the case of the optical measuring system, therefore, only light which is reflected on the band is measured. For this purpose, the subjected to detection all round, on the entire periphery. In this way, detection can take place
ever at high band speeds of, for example, 300 m/min or
5 m/sec. The low resolution is achieved through the fact that measuring systems of low sensitivity are used, or that high threshold values for deviations from a normal signal are set in the computer 8, in order to indicate extraneous fibres. The resolution is also predetermined, in particular, by the threshold values 28, 32, there being started in the computer, when the threshold value 28 is exceeded, a counting operation for the period of time 31, to which operation the threshold value 32 in turn applies.
In the case of a section 33 (figure 5), or ultimately also in the case of other textile machines which process band, it is possible to provide the sensor 3 5 which emits signals to the computer 38. The latter activates, for example, a band-cutter 36 which cuts the band 37 When contaminants are detected, so that the vitiated part of the band can be removed.
Process for detecting extraneous substances and extraneous fibres in a fibrous composite, characterised in that the fibrous composite (2) is shaped to form a band (4, 17) and that the extraneous substances and extraneous fibres in the band detected on the surface (22).
Process according to claim 1, characterised in that, after detection of the extraneous substances and extraneous fibres, one operation out of a group of operations comprising marking of the band, marking of the carrier of the band, removal of the band, interruption of the band, stopping of the processing device and triggering of an alarm, is carried out.
Device for detecting extraneous substances and tyrannous fibres in a fibrous composite, characterised by a sensor (6) in the region of a moving band (4), which sensor is disposed so as to at least partly enclose the band.
Device according to claim 3, characterised in that the sensor is constructed so as to enclose the band on all sides.
Device according to claim 3, characterised in that the sensor is connected to one element out of a group of elements comprising a marking device (15, 16), a band-cutter (36) and an alarm device.
Device according to claim 3, characterised in that the sensor (35) is disposed at the exit (34) from a section (33)•
7. Device according to claim 3, characterised in that the
sensor is disposed between the delivery point of a
carder (1) and a can (5).
8. Device according to claim 3, characterised in that the
sensor has at least one measuring system which works
optically and analyses light rays reflected on the
10 A process detecting extraneous substances and extraneous
fibres in a fibrous composite, substantially as herein described
with reference to the accompanying drawings.
|Indian Patent Application Number||2489/MAS/1997|
|PG Journal Number||50/2007|
|Date of Filing||03-Nov-1997|
|Name of Patentee||M/S. USTER TECHNOLOGIES AG|
|Applicant Address||WILSTRASSE 11,CH-8610 USTER|
|PCT International Classification Number||D 01 G -31/00|
|PCT International Application Number||N/A|
|PCT International Filing date|