Direct control of fiber testing or processing performance parameters by application of controlled, conditioned gas flow

Abstract: Conditioned gas flows are applied at various critical locations in instruments and apparatus for testing and processing textile fibers, such as cotton. In the context of test instruments, a standard test zone environment (which becomes part of the test record) is effected by the introduction of controlled conditioned gas flows directly into a testing zone, including into testing instruments themselves. In the context of processing apparatus, direct control of machine performance parameters is effected by "controlling parameters", which are in turn effected by the application of conditioned gas flows. A plurality of "performance parameters", which may be in conflict with each other, may be controlled in accordance with a predetermined compromise control strategy, carried out by feedback or feedforward control systems implementing modern statistical control approaches.

Description: FIELD OF THE INVENTION The invention relates to a method for processing fibre in a machine having a plurality of processing stages, whereas at least one parameter is measured at each processing stage and a conditioned gas flow is applied at a point appropriate for each processing stage and an apparatus for processing fibre comprising a fibre processing machine having a plurality of processing stages, a sensor for each processing stage for measuring at least one parameter, a conditioned supply system for applying at a point appropriate for each processing stage a gas flow conditioned by at least one controlling parameter and a control system connected to each of said sensors and to each of said conditioned supply systems. BACKGROUND OF THE INVENTION In order to optimize yarn processing performance and end-product quality, tests are commonly applied to textile entities which include fibers and undesirable entities such as neps and trash. Zellweger Uster, Inc., Knoxville, Tennessee; Uster, Switzerland; and others manufacture a wide range of fiber and yarn testing instruments, both of the laboratory type and the on-line process control type, that are increasingly used by textile producers worldwide. In today's highly competitive and quality conscious marketplace the use of these instruments in laboratory testing and process monitoring has gone beyond simply giving the user a competitive advantage. Their use has, in the area of classing cotton for loan eligibility, been dictated by the U.S. government, and has otherwise become a requirement of business survival. Raw materials are procured and lots of finished goods are accepted or rejected based on fiber and yarn properties as determined by these instruments. For example, nearly 100% of U.S. cotton bales are classified as to fiber length, fiber strength/elongation, color, micronaire, and trash content by HVI (High Volume Instrumentation) systems (manufactured by Zellweger Uster, Inc., Knoxville, Tennessee), thus replacing the traditional human cotton classer. The measured results determine the monetary value of the bale and serve as a first process control measurement for spinning mills. Increased demands on fiber properties, such as increased fiber cleanliness and decreased neps and short fiber content, have brought increased demands for instruments that measure those properties and increased expectations for the precision and accuracy of the measurements. For instance, the AFIS (Advanced Fiber Information System), also manufactured by Zellweger Uster, Inc., Knoxville, Tennessee and described in the papers "Utilization of the Complete Fiber Length Distribution from the Advanced Fiber Information System" and "Electro-Optical Trash Particle Counting and Sizing", Bremen Cotton Conference, Bremen, Germany, and in various copending patent applications referenced hereinbelow, can make measurements of fiber trash content, fiber length distributions (including short fiber content), and fiber nep levels. MANTIS, also manufactured by Zellweger Uster, Knoxville, Tennessee, can measure single fiber breaking tension, elongation, and diameters. MANTIS is described in U.S. Pat. No. 5,138,879. Both instrument and process machinery manufacturers have long known that the microenvironment surrounding the test or processing zones can have a profound effect on fiber measurement and processing performance parameters. For example, cotton fiber is mostly cellulose and is highly hygroscopic. Increasing moisture content increases strength, causes fiber swelling, aggravates cleaning and sugar-related "stickiness", and reduces electro-static effects. These and other changes in fiber behavior associated with the test or processing micro-environment are well known and are utilized to a limited extent by textile fiber processors by controlling the macroenvironment. In ginning, for example, moisture content in the fiber is purposefully reduced to about 5% or below by driers. This allows more effective cleaning but, along with other effects, weakens the fibers and aggravates static charge problems. On the other hand, in weaving rooms where fiber and associated yarn strength is critical, the relative humidity may be held as high as 85%, corresponding to a moisture content of about 9% in the yarn. However, precise macroenvironmental control in testing laboratories or manufacturing facilities is difficult, expensive and, in most cases, far less effective than desired. A large controlled space offers a buffer to small perturbations in, for example, humidity, temperature, and ion concentration, but is slow to respond to control actions. It is common to find very expensive (millions of dollars for large production areas) macroenvironmental control systems which, indeed, control relative humidity and temperature to ± 2%, and ± 0.55°C (1°F) but, unfortunately, allow the test or production zone to fluctuate ± 10% and 2.75°C (± 5°F). As discussed in US 4,512,060, which represents the closest prior art, and in US 4,631,781 and 4,686,744, increasing demands are being placed on fiber properties as textile processing machinery production rates increase and as the tolerances of textile processing machinery for variances in the fiber properties decrease. Current production and harvesting methods inherently entrain more foreign matter content into cotton fiber, for example, such that the ginning and cleaning actions required to achieve a given percentage of foreign matter content are increasing. Increased cleaning is always at the expense of fiber loss and damage. The incompatibility between the goals of clean versus undamaged fiber increases the difficulties faced by producer, ginner, merchant and spinner. Providing clean and undamaged fiber is a major, world-wide problem and improved processing methods and apparatus are urgently needed, especially in the areas of test zone and process zone environmental control. As generally recognized in the above-identified US Pat. Nos. 4,512,062, 4,631,701 and 4,686,744, it is advantageous to condition air or other gas, such as transport gas, in both processing and testing machines for improved machine operation. For example, as disclosed in those patents, there can be a preferred state of the fiber with regard to humidity and static charge for a particular operation, such as a cleaning operation. It is further recognized in those patents that parameters such as humidity and electrostatic charge of the fiber may be different at each of a plurality of different processing stages. Although temperature, humidity and static charge are perhaps the most obvious parameters of transport gas which may be conditioned, others are possible. For example, the above-identified patents also disclose the conditioning of transport gas as to humidity, temperature, pressure, gas composition, free charge concentration, static charge, radioactive particle concentration, velocity and pressure fluctuations. Other examples of controlling temperature and humidity in particular in a textile processing machine are disclosed in US 4,527,306 and US 5,121,522. Those patents describe systems in which pneumatic transport air within a textile processing machine is conditioned with respect to temperature and humidity, employing a feedback control system. US Pat. No. 5,121,522 in particular discloses a system for measuring "humidity" and temperature of fiber tufts directly for use in controlling an air conditioning system. As noted in those patents, one reason for control is that if, for example, the transport air is too dry, electrostatic charges can cause undesirable fiber accumulations within the equipment. On the other hand, if the transport air is too humid, balling of fiber tufts can result. Thus, the control of moisture content in fiber processing is well known. Further, under the influence of conditioned gas flow, it is known that single fibers can reach a point of equilibrium (e.g. with respect to moisture content) almost instantaneously, whereas tufts or masses of fibers require longer periods of time to reach equilibrium. There are, however, a number of conflicting considerations, which have not heretofore been effectively addressed. It is known, for example, that fiber is best cleaned when fiber moisture content is relatively low, for example, below 5%. It is also known that the strength of cotton fiber is a maximum at a relatively higher moisture content, for example, above 5%. Strength of cotton fiber affects the degree of undesirable fiber breakage during processing operations. SUMMARY OF THE INVENTION Accordingly, it is a broad object of the invention to improve the overall performance of fiber testing instruments and processing machines through the application of appropriately controlled conditioned gas flows. In accordance with the invention, it is recognized that direct control of machine performance parameters, not just the processing zone environment, may be effected by means of what are herein termed "controlling parameters" effected by the application of conditioned gas flows. By way of example, and without limitation, machine performance parameters include trash content, nep content, short fiber content, trash removal efficiency, nep removal efficiency, short fiber removal efficiency, and machinery production efficiency. Suitable sensors exist for measuring each of these performance parameters for application in a feedback control system. By way of example, and not limitation, controlling parameters which may be effected by application of conditioned gas flows include humidity, temperature, velocity, pressure, velocity fluctuations, pressure fluctuations, gas composition, free charge concentration, static charge, and radioactive particle concentration. Moreover, in accordance with the invention it is recognized that the relevant performance parameters and consequent controlling parameters differ at different stages in a textile processing apparatus, and in accordance with the invention these are separately controlled. In accordance with the invention, a method for processing fiber in a machine, having a plurality of processing stages, one of which may be a carding stage, whereas at least one parameter is measured at each processing stage and a conditioned gas flow is applied at a point appropriate for each processing stage. This method is characterised by measuring at least one processing performance parameter from the list presented hereinabove, and controlling the at least one performance parameter by deliberately applying, during processing, a gas flow conditioned by at least one controlling parameter, such as the controlling parameters in the list presented hereinabove. An apparatus in accordance with the invention includes a fiber processing machine having a plurality of processing stages. A sensor is provided for each of the processing stages for measuring at least one parameter, and there are respective conditioned supply systems for applying, at a point appropriate for each stage, a gas flow conditioned by at least one controlling parameter which affects the performance parameter for the particular stage. A feedback control system is connected to the sensors and to the conditioned supply systems. The apparatus is characterised in that said sensor is a sensor for measuring a processing performance parameter, in that said control system is designed for controlling the at least one processing performance parameter for each of said processing stages by controlling the at least one controlling parameter for each particular stage. BRIEF DESCRIPTION OF THE DRAWINGS While the novel features are set forth with particularity in the appended claims, the invention, both as to organization and content, will be better understood and appreciated, from the following, taken in conjunction with the drawings, in which: FIG. 1 depicts control and conditioning units for test zone environmental control; FIG. 2 is a block diagram of a control system in accordance with the invention connected to a multi-stage fiber processing machine shown in highly schematic form; FIG. 3 depicts a carding stage; FIG. 4 is an enlarged portion of the feed end of the FIG. 3 carding stage; FIG. 5 is an enlarged portion of the doffer end of the FIG. 3 card; FIG. 6 is a plot depicting conflicting machine performance parameters; and FIG. 7 is a diagram of a gas conditioning system. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Test Zone Environmental Control In Fig. 1, separate control 326 and conditioning units 310 are shown. Monitorig sensors M1, M2, etc., and control electronics within control unit 326 are well known in the art. Greater detail is now provided for conditioning unit 310. Air is drawn into inlet 400 by fan 402 and first passes through dust filter 404 which might be a HEPA (High Efficiency Particle Arrester) filter. The discharge of fan 402 then passes over refrigeration coils 406. Refrigeration is provided by compressor system 408. Water is supplied at inlet 410 for condenser cooling and for steam humidification. A cooling water and condensate drain 412 is shown. The cooled and dried air in plenum 414 is then divided among eight final conditioning modules 416. Each conditioning module 416 has a reheat coil 418, a steam bar 420, and ion grid 422, and a flow control damper 424. Each of the conditioning elements 418-424 is separately controlled by control unit 326 in response to signals delivered on lines 325 from individual monitoring sensors M described above. When the test zone environment under the influence of one of the conditioning modules is itself controlled, the monitoring sensors respond to one or more of humidity, temperature, velocity, pressure, velocity fluctuations, pressure fluctuations, gas composition, free charge concentration, static charge, and radioactive particle concentration, or the like and the control system 326 causes the output of that module to be adjusted to the desired values for the test zone under the influence of that module. This is direct control of the fiber testing zone parameters. When the parameters of the processing machinery performance are controlled by application of conditioned gas flows, and the monitoring sensors M respond thereto, this is direct control of processing performance parameters, not of the processing environment, and is a further embodiment of our invention whose disclosure we now provide. Process Zone Environmental Control Referring now to FIG. 2, depicted in highly generalized form is a fiber processing machine set 20 having a plurality of sequential processing stages, represented as opening-cleaning machines 22, cards 24 and draw frames 26. Fiber material in the bale state 28 is opened, cleaned and converted by machinery line 22 into the tuft state 30. The tufts of fibrous material exit the opening-cleaning line 22 and are formed into a mat 30, which then enters the card 24, emerging as sliver 32, which enters the draw frame 26, emerging from the draw frame 26 as blended sliver 34. The overall machine set 20 is representative not only of the processing of fiber starting with bale opening and extending through the drawing operation, but is also representative of continuing machine processes in the production of yarn, including draw frames, combers, roving machines, and rotor and/or ring spinning frames. Concurrently-filed EP 604 876 entitled "Methods of Optimally Controlling Fiber Processing Machines" lists and discusses yarn manufacturing machinery, describes the "machinery characteristics" of the rotor spinbox in particular, and provides novel methods for optimal control of fiber processing machinery in general. Machinery characteristics relate processing performance parameters at the various machinery outputs as they are affected by input parameters and machinery operational settings. Those disclosures are incorporated herein by reference. It is specifically noted that the instant disclosures for controlling processing performance parameters with conditioned gas flows constitute a further application of the above-referenced invention. Associated with each of the machinery stages 22, 24 and 26 is a measuring station M, shown as representative sensors 36, 38 and 40, as well as an environmental control station E, shown as representative conditioned gas supply systems 42, 44 and 46. The sensors 36, 38 and 40 are each known devices, and do not themselves constitute the subject matter of this invention. In general, the sensors 36, 38 and 40 measure machine performance parameters, such as trash content, nep content, short fiber content, and related parameters such as trash removal or generation efficiency, nep removal or generation efficiency and short fiber removal or generation efficiency. In general, the machines can both remove and generate and the efficiency can be less than unity (removal) or greater than unity (generation). For example, a poorly adjusted card can break up trash particles, create more neps than it removes, and break fibers. Although a single sensor 36, 38 and 40 is shown associated with each of the stages 22, 24 and 26, it will be appreciated that each of the indicated sensors is representative of a plurality of sensors which may be associated with each particular stage. Appropriate sensors may also be provided to measure various machine efficiencies, including production efficiency. The conditioned gas supply systems 42, 44 and 46 serve to apply conditioned gas flows conditioned by at least one controlling parameter, such as humidity, temperature, velocity, pressure, velocity fluctuations, pressure fluctuations, gas composition, free charge concentration, static charge, and radioactive particle concentration. Although the conditioned gas supply systems 42, 44 and 46 are shown as separate elements, it will be appreciated that the separate elements depicted may comprise elements of an overall air supply system, for example having a single blower, having a plurality of branch ducts, with individual control elements such as heaters, humidifiers, controlled dampers and/or filters in the individual ducts. In accordance with the invention, and as is described hereinbelow in greater detail with reference to FIGS. 3-6 in the context of a card, such as the card 24, the machine performance parameters as measured by the sensors 36, 38 and 40 are controlled by controlling the controlling parameters delivered by the conditioned gas supply systems 42, 44 and 46. Accordingly, there is provided a feedback control system, generally designated 50, which receives outputs of the sensors 36, 38 and 40 to derive signals for controlling the conditioned gas supply systems 42, 44 and 46. Individual feedback loops are indicated in highly schematic fashion as dash lines 52, 54 and 56. Individual feedforward lines are 53, 55 and 57. Although not illustrated in FIG. 3 , it will be appreciated that each of the conditioned gas supply systems 42, 44 and 46 may include its own feedback loop. For example, if the feedback control system 50 directs one of the conditioned gas supply systems 42, 44 or 46 to maintain a given percentage relative humidity at a particular supply point, then that particular conditioned gas supply system may itself include a relative humidity sensor which, through feedback control, directs the operation of a humidifier element, such as a water spray. It will further be appreciated that the feedback loops 52, 54 and 56 are greatly simplified, in that each is shown connected to a single one of the sensors 36, 38 and 40 whereas, in accordance with the invention, the feedback control system 50 may take into account a plurality of conflicting machine performance parameters, and implement an overall optimal control strategy employing modern statistical control methodology to achieve an overall best compromise. It may also be noted that, while the diagram of FIG. 2 implies a machine performance parameter sensor at the output of each stage, and a conditioned gas supply system at the input of each stage, such is not necessarily the case in any given embodiment. Thus, a machine performance parameter sensor may be applied wherever appropriate. Such may be within a stage, at the immediate exit of the stage, or downstream of the particular stage. Similarly, a conditioned gas supply may be applied to fiber material as it is conveyed to a particular processing stage, to the fiber immediately as it enters the particular processing stage, to fiber within the particular processing stage, or even to fiber upstream of a particular fiber processing stage, or any combination. With reference now to FIGS. 3-6, by way of example a particular application of the invention with reference to a card, such as the FIG. 2 card 24, will now be described. FIG. 3 depicts a carding stage 100 in overview, FIG. 4 is an enlarged view of the feed or licker-in section of the FIG. 3 carding stage 100, and FIG. 5 is an enlarged view of the doffer or exit portion of the FIG. 3 carding stage 100. At the outset, it may be noted that the carding stage 100 is generally conventional, but is modified to include various measuring stations or sensors ("M" prefix), as well as environmental control stations ("E" prefix), where conditioned gas flows are applied. Central to the card stage 100 is a card cylinder 102 covered with card wire 104 of conventional construction, and rotating with a circumferential velocity of, for example, 10 meters per second. Closely adjacent to the card cylinder 102 are a plurality of card flats 106. Fiber stock 30 is conveyed along a perforated plate 108, and reaches a feedroll 110 which transfers the fiber to a licker-in cylinder 112, in the process. The licker-in cylinder 112 rotates for example at a circumferential velocity of 20 meters per second, and in turn transfers the fiber to the rotating card cylinder 102, where it is subjected to combing action between the carded wire 104 and flats 106. A rotating doffer cylinder 114 removes the carded fibers from the rotating card cylinder 102, to produce a web 116. Web 116 is approximately one meter in width and has a linear density of about 5 grams per meter. Trumpet 117 collects the web and forms it into a sliver 118 whose linear density is also about 5 grams per meter, whose diameter following the trumpet is about one centimeter, and whose delivery speed is about two meters per second. In an implementation of the invention, the carding stage 100 is modified to include the mounting of the measuring stations at critical points, such as, but not limited to, measuring station M1 where fiber stock 30 is supplied to the card, M2 where fiber stock is taken up by the feedroll 110, M3 where fiber is on the licker-in cylinder 112, M4 where fiber is on the card cylinder 102, M5 where fiber is on the doffer cylinder 114, and M6 and M7 where characteristics of the web 116 or sliver 118 are measured, respectively. The environmental control stations represent points where conditioned gas flow is applied, for example in using any of the techniques disclosed in the above-identified US Pat. Nos. 4,512,060, 4,631,781 and 4,686,744. Thus as examples, a suitable upper plenum 130 generally encloses the fiber material moving along the perforated feed plate 108, and a conditioned gas flow introduced at environmental control station E1 acts on fiber conveyed along the perforated feed plate 108. Flow E1 is pulled through the fiber mat 30 by suction applied to lower hood 131 and perforated feed plate 108. Preferably, the licker-in cylinder 102 is perforated and conditioned flows are introduced as at E2, E3 and E4 to serve the dual purposes of conditioning the fiber and aiding in the extraction of dust, trash and microdust in the manner disclosed in the above-identified US Pat. Nos. 4,512,060, 4,631,781 and 4,686,744. Station E5 introduces conditioned gas to fiber on the card cylinder 102, and environmental control station E6 introduces conditioned gas to fiber on the doffer cylinder 114 which may also be perforated, as shown in FIGS. 3 and 5 Environmental control station E7 introduces conditioned gas to the web 116 leaving the crush rolls 115. A specific example will now be considered illustrating the concepts of the invention. At measuring station M2 where fiber is about to enter the licker-in cylinder 112, moisture content, trash and short fiber content are all measured. Numerous other performance parameters can be measured. By way of example, moisture content may be 5%, trash may be 500 particles per gram, and short fiber content 8%. At M5 or M6, short fiber content and trash content at the output of the card are measured. This is a simplified example, and we consider only one controlling parameter, namely, moisture or water applied at environmental control station E1 to control the absolute humidity of the gas flow. Numerous other controlling parameters and points of their application can be used. The absolute humidity at E1 can be influenced in any way, for example, by ultrasonic humidification, spray nozzles, or steam injection. Relative humidity can be influenced by temperature control. Humidity at E1 controls moisture content at M2, which in turn controls trash and short fiber content at M5, as is discussed in detail hereinbelow. As an example, relative humidity at E1 may be 50%. Moisture content, as measured at M2, affects both the trash content and the short fiber content as measured at M6, but in conflicting manners. The conflict is plotted in simplified form in FIG. 6. The abscissa of FIG. 6 is moisture content as measured at M2 and is controlled directly through conditioning of the gas introduced at E1. The left ordinate is trash as measured at measuring station M6 and plotted as line 150. The right ordinate is short fiber content in percent by weight of fibers whose length is less than 12 mm (1/2 inch), plotted as line 152. Monitoring station M6 may be the image analysis system described in concurrently-filed EP 0 604 875, entitled "Acquisition, Measurement, and Control of Thin Webs of In-Process Textile Materials". In this example, there is a nominal operating point of 100 trash particles per gram, which is associated with a moisture content at M2 of 5%. As moisture content increases, trash content also increases, and trash content decreases as moisture content decreases. In this somewhat arbitrary example, at a 4% moisture content the resultant trash content is 80 trash particles per gram, and at a 6% moisture content, the trash content is 120 particles per gram. In general, it is desirable to minimize trash content. Considering the short fiber content, at the nominal 5% moisture content point, short fiber content in this example is 8%. As moisture content decreases, short fiber content undesirably increases, due to increased damage by the card because the fibers are weaker. Conversely, as moisture content increases, short fiber content decreases. Thus, the relationship is an inverse one. In this particular example, a moisture content of 6% results in a 6% short fiber content, while a moisture content of 4% results in a short fiber content of 10%. From FIG. 6 it is apparent that the machine performance parameters of short fiber content and trash content are in conflict, and it is an important aspect of the invention to appropriately control both of these exemplary parameters in an optimized manner. Consider now that the machine is operating with a given supply of cotton and, for purposes of initial reference, is operating at a trash content at M5 at 100 per gram, and a short fiber content of 8% at M5. Input fiber parameters as measured at M2 are 500 per gram for trash, and 8% short fiber content. Since the card 102 can both remove and generate short fibers, its net impact in this example is described by an efficiency of unity. Card 102 decreases the trash content from 500 per gram down to 100 per gram and thus has a trash removal efficiency of 0.80. Assume a change, for example caused by some change in the nature of the cotton fiber 30 being introduced into the machine. By way of particular example, assume that the trash content measured at M2 increases from 500 per gram to 1000 counts per gram, and that short fiber content remains at 8%. Assuming the process is linear, trash content measured at M6 would go from 100 per gram to 200 per gram, at the same moisture content of 5%, all other things being equal. In accordance with the invention, what is controlled is not the 5% moisture content at M2, nor the 50% relative humidity at E1; what is controlled is the performance of the machine, in this case the output or sliver parameters trash content and short fiber content. In accordance with the modern statistical control methodology described in the above-referenced copending application, a suitable compromise can be developed and implemented, based on analysis of a particular machine. Such a control system would function, for example, as follows. The control system could, for example, reduce the moisture content as measured at M2 from 5% to 4% by reducing the humidity of the air introduced at E1 as required. From FIG. 6, we would expect a 20% reduction in trash content. Trash of 200 counts per gram would accordingly be decreased to 160 counts per gram. However, if the moisture content at M2 is decreased to 4%, the short fiber content as measured at M5 goes from 8% to 10%. Thus, a difficult choice is faced, namely, whether reducing trash content to 160 counts per gram M6 has more positive impact on gross profit of the entire process than the negative impact of increasing the short fiber content to 10%. The impact on gross profit might in reality be positive since the higher trash content material can be purchased at lower cost and the value of yarn ultimately produced may be affected only slightly. On the other hand, increased short fiber content degrades yarn strength and uniformity and the marketplace treats such degradations harshly. Thus, the system can respond in several different ways. In whatever event, a computer associated with the feedback control system appropriately programmed in accordance with modern statistical control methods, is searching all the time for what the optimum value would be for short fiber content in view of trash content, to reach a level of compromise encompassing yarn value, as well as other performance standards. In a typical case, the operator of the machine would choose to accept a higher level of trash content in order to minimize short fiber content, and thus would program the control system to not reduce the moisture content to such a degree. The penalty in the marketplace for short fiber content is generally more severe than the penalty for trash content because short fiber content degrades yarn strength and evenness. In summary, it is desirable to minimize the short fiber content, and it is also desirable to minimize the trash content. Yarn value is adversely affected by a high percent content of either trash or short fiber content, the value being reduced more by high short fiber than by trash content. Therefore, a tradeoff is often found to be valuable, and the optimum moisture content is therefore a compromise level to optimize yarn value. Thus, it is desirable to change the air supply conditions to specific points on a carding machine to satisfy the results of fiber cleaning and short fiber elimination. Multiple control points may be employed. For example, in addition to E1, E4 and E5 may be utilized. It is recognized that fiber damage occurs at two points in particular, where the feedroll 110 delivers fiber to the licker-in cylinder 112, and where the fibers entertain vigorous carding action between to the card cylinder 102 and the card flats 106. Thus, relatively low moisture content fiber at M2 can be introduced to the licker-in cylinder 112 for enhanced cleaning at that point where pins on the licker-in cylinder 112 impact the fibers as they come over the feedroll 110 and feed plate 111. This increased damage is offset, however, by decreasing damage associated with the card cylinder 102 and flats 106 by introducing humid air through E4 and E5. Similarly, in anticipation of subsequent processing, at E6 and E7 moisture content can be elevated as desired. For example, a higher moisture content would be desirable for feeding a draw frame or ultimately, a rotor spinning machine. FIG. 7 illustrates in overview a gas flow conditioning system for supplying conditioned air at three selected points on the FIG. 3 card 100, selected, for example, among the environmental stations designated E1, E2, E3, E4, E5, E6 and E7. For convenience of illustration, only three process zones are shown in FIG.7 respectively designated 202, 204 and 206. There is a common supply duct 208 with respective branches 210, 212 and 214. In series with each of the branches 210, 212 and 214 are appropriate control elements, collectively designated 216, which may comprise elements such as dampers, heater coils, humidifiers, filters or ion grids. Central to the supply system is an air washer 220, for example an air washer available from Pneumafil Corp., Charlotte, North Carolina or Luwa-Bahnson, Winston-Salem, North Carolina. The air washer 220, with appropriate control components, provides an air flow of a predetermined initial humidity, as determined to be appropriate for the system. This air flow is driven by a blower 222 through a volume damper 224 into the supply duct 208, which supplies individual branches 210, 212 and 214. The supply air fan 222 thus furnishes air to the three or more points on the card, as further modified by the control elements 216 and in response to control signals 217a, 217b, etc. Suction or return air from the card process zones, plus any air by-passed through damper 231, is collected by a duct 230, and is cleaned by a two-stage filter comprising a primary filter 232 and a secondary filter 234 in the form of a drum or roll filter. Return air blower 236 draws air from the filters 232 and 234 and delivers the return air into a mixing plenum 238, which may optionally be followed by a tertiary filter 240, which then delivers cleaned air to the air washer 220. The mixing plenum 238 and return air fan 236 in particular would be provided in situations when it is desirable to operate the system on an economy cycle, avoiding the need for a chilled water or other cooling system when outside air conditions allow the maintenance of the desired temperature of the air flow by means of evaporative cooling. The mixing plenum 238 accordingly has associated with it return air dampers 242, outside air dampers 244, and exhaust air dampers 246. In hot weather, or when outdoor conditions will not allow the maintenance of the required temperature without additional cooling, a chilled water cooler 250, for example a unit supplied by the Trane Company, can be employed to provide control of the spray water temperature, and thus the temperatures and/or humidity of the supply air or gas via control of a chilled water supply valve 252, which allows chilled water to enter an air washer recirculating pump 254. Another valve 256 is provided to assure a constant flow of water through the water chiller, averting possible freeze up conditions. In lieu of spraying chilled water in the air washer, a "closed loop" chilled water system may be utilized, whereby the cooling effect is achieved by means of coils located in the air stream to be conditioned, through which chilled water is circulated as required to achieve the desired conditions. Associated with the unit 250 is a cooling tower 258. While specific embodiments of the invention have been illustrated and described herein, it is realized that numerous modifications and changes will occur to those skilled in the art.

Claims: Method for processing fibre in a machine (20) having a plurality of processing stages (22, 24, 26), whereas at least one parameter is measured at each processing stage and a conditioned gas flow is applied at a point appropriate for each processing stage, characterised by measuring at least one processing performance parameter selected from a group consisting of trash content, nep content, short fibre content, trash removal efficiency, nep removal efficiency, short fibre removal efficiency, machine production efficiency and fibre value, and controlling the at least one processing performance parameter by deliberately applying a gas flow conditioned by at least one controlling parameter. Method according to claim 1, wherein said controlling parameter is selected from the group consisting of humidity, temperature, ion content, velocity, pressure fluctuations, gas composition and radioactive particle concentration. Apparatus for processing fibre comprising a fibre processing machine (20) having a plurality of processing stages (22, 24, 26), a sensor (36, 38, 40) for each processing stage for measuring at least one parameter, a conditioned supply system (42, 44, 46) for applying at a point appropriate for each processing stage a gas flow conditioned by at least one controlling parameter and a control system (50) connected to each of said sensors and to each of said conditioned supply systems, characterised in that said sensor is a sensor for measuring a processing performance parameter, in that said control system is designed for controlling the at least one processing performance parameter for each of said processing stages by controlling the at least one controlling parameter for each particular stage.

Inventors: SHOFNER FREDERICK M, TOWNES MARK G, SHOFNER, FREDERICK M., TOWNES, MARK G.
Applicants: ZELLWEGER USTER INC, ZELLWEGER USTER, INC.
Application year: 1993
Main classification: G01N33
IPC codes: F26B21, D06H3, G01N33, D01G23