Abstract:
A method of determining a testing volume for a micronaire measurement by containing a fiber sample within a micronaire chamber having a length and at least one movable end wall. A flow is initiated along the length of the micronaire chamber. The fiber sample is compressed within the micronaire chamber by advancing the movable end wall, and the advancement of the movable end wall is stopped when at least one property of the flow attains a set point. The position of the movable end wall defines the testing volume. In this manner, there is provided a convenient method of setting a testing volume and acquiring the information needed to take a micronaire measurement.

Description:
FIELD 
       [0001]    This invention relates to the field of fiber property measurement. More particularly, this invention relates to micronaire measurement of fibers. 
       BACKGROUND 
       [0002]    Micronaire readings are derived from Koxeny&#39;s equation, which provides an approximation for the permeability of powders having a negligible number of blind pores. This equation characterizes the relationship of air flow resistance over a surface with a known mass in a known volume, as in: 
         [0000]    
       
         
           
             M 
             = 
             
               
                 ( 
                 
                   R 
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                    
                   M 
                 
                 ) 
               
               x 
             
           
         
       
       
         
           
             when 
              
             
               : 
             
           
         
       
       
         
           
             
               R 
                
               
                   
               
                
               M 
             
             = 
             
               
                 [ 
                 
                   
                     ( 
                     
                       HMC 
                       - 
                       LMC 
                     
                     ) 
                   
                   
                     ( 
                     
                       LMP 
                       - 
                       HMP 
                     
                     ) 
                   
                 
                 ] 
               
                
               
                 [ 
                 
                   LMC 
                   + 
                   
                     ( 
                     
                       LMP 
                       - 
                       P 
                     
                     ) 
                   
                 
                 ] 
               
             
           
         
       
       
         
           
             and 
              
             
               : 
             
           
         
       
       
         
           
             X 
             = 
             
               1 
               + 
               
                 
                   [ 
                   
                     
                       ( 
                       
                         W 
                         - 
                         10 
                       
                       ) 
                     
                      
                     100 
                   
                   ] 
                 
                  
                 
                   [ 
                   
                     0.00125 
                     - 
                     
                       
                          
                         
                           3.5 
                           - 
                           
                             R 
                              
                             
                                 
                             
                              
                             M 
                           
                         
                          
                       
                        
                       0.00015 
                     
                   
                   ] 
                 
               
             
           
         
       
     
         [0003]    where, over a sample weight range of about eight grams to about twelve grams: 
         [0004]    M=Corrected micronaire value 
         [0005]    RM=Raw micronaire value 
         [0006]    HMC=High calibration cotton value 
         [0007]    LMC=Low calibration cotton value 
         [0008]    LMP=Pressure of low calibration cotton value 
         [0009]    HMP=Pressure of high calibration cotton value 
         [0010]    P=Pressure of cotton under test 
         [0011]    W=Weight of cotton under test, grams 
         [0012]    Even though there are certain properties of the fiber sample, cotton for example, that must be known or derived in order to produce a micronaire value, these properties can be determined in a variety of different ways—some ways easier or more convenient than others. Likewise, the method by which the micronaire readings are taken can also vary in efficiency, speed, or convenience of operation. 
         [0013]    What is needed, therefore, is a system for measuring micronaire that provides benefits, such as those mentioned above, at least in part. 
       SUMMARY 
       [0014]    The above and other needs are met by a method of determining a testing volume for a micronaire measurement by containing a fiber sample within a micronaire chamber having a length and at least one movable end wall. A flow is initiated along the length of the micronaire chamber. The fiber sample is compressed within the micronaire chamber by advancing the movable end wall, and the advancement of the movable end wall is stopped when at least one property of the flow attains a set point. The position of the movable end wall defines the testing volume. 
         [0015]    In this manner, there is provided a convenient method of setting a testing volume and acquiring the information needed to take a micronaire measurement. 
         [0016]    In various embodiments, the at least one property of the flow is pressure or volumetric flow rate. The movable end wall is advanced with a stepper motor in one embodiment. The flow is preferably a flow of air. Preferably, the at least one property of the flow and the testing volume are used to calculate the micronaire measurement. 
         [0017]    According to another aspect of the invention there is described a method of preparing a fiber sample for a micronaire measurement by forming the fiber sample into a plug having a cross-sectional shape and size that are substantially similar to a cross-sectional shape and size of a micronaire chamber in which the micronaire measurement is to be taken, before inserting the plug into the micronaire chamber. 
         [0018]    According to another aspect of the invention there is described a method of preparing a fiber sample for a micronaire measurement by placing an amount of unformed fiber as a fiber sample in a fiber sample loader, and bringing together forming surfaces of the fiber sample loader to form the fiber sample into an elongate plug having a cross-sectional shape and size that are substantially similar to a cross-sectional shape and size of a micronaire chamber in which the micronaire measurement is to be taken, before inserting the plug into the micronaire chamber. 
         [0019]    According to another aspect of the invention there is described a method of preparing a fiber sample for a micronaire measurement by placing an amount of unformed fiber as a fiber sample in a fiber sample loader. A first lateral forming surface of the fiber sample loader is brought toward a second lateral forming surface of the fiber sample loader and the fiber sample is formed between the first lateral forming surface and the second lateral forming surface to form three sides of the fiber sample. A vertical forming surface of the fiber sample loader is brought down between the first lateral forming surface and the second lateral forming surface and onto the fiber sample to form a fourth side of the fiber sample, thereby forming the fiber sample into an elongate plug having a cross-sectional shape and size that are substantially similar to a cross-sectional shape and size of a micronaire chamber in which the micronaire measurement is to be taken. The plug is inserted into the micronaire chamber with a plunger having a cross-sectional shape and size that are substantially similar to the cross-sectional shape and size of a micronaire chamber in which the micronaire measurement is to be taken. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]    Further advantages of the invention are apparent by reference to the detailed description when considered in conjunction with the figures, which are not to scale so as to more clearly show the details, wherein like reference numbers indicate like elements throughout the several views, and wherein: 
           [0021]      FIG. 1  depicts a micronaire measurement system according to a preferred embodiment of the present invention, with the loader in the sample reception position. 
           [0022]      FIG. 2  depicts a micronaire measurement system according to a preferred embodiment of the present invention, with the loader in the lateral plug  18  formation position. 
           [0023]      FIG. 3  depicts a micronaire measurement system according to a preferred embodiment of the present invention, with the loader in the vertical plug  18  formation position. 
           [0024]      FIG. 4  depicts a micronaire measurement system according to a preferred embodiment of the present invention, with the loader in the plug  18  insertion position. 
           [0025]      FIG. 5  depicts a micronaire measurement system according to a preferred embodiment of the present invention, with the plug  18  in the micronaire chamber  28 . 
           [0026]      FIG. 6  depicts a micronaire measurement system according to a preferred embodiment of the present invention, with the loader in the plug  18  expulsion position. 
           [0027]      FIG. 7  is a functional block diagram of a micronaire measurement system according to a preferred embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
     Sample Loading and Unloading 
       [0028]    With reference now to  FIG. 1 , there is depicted a micronaire measurement system  10  according to a preferred embodiment of the present invention. As depicted in  FIG. 1 , the sample loading mechanism  12  is in the sample reception position, with the lateral plug formation member  14  and the vertical plug formation member  16  extended. With the loader  12  in this position, the loader  12  is adapted to receive the fiber sample  18 , on which micronaire measurements are to be made. The fiber sample  18  may be any one or blend of more than one fiber types, but in the preferred embodiment the fiber sample  18  is cotton fiber. 
         [0029]    The various elements of the loader  12  are preferably adapted so as to form the fiber sample  18  into a plug  18  that is substantially the same cross-sectional shape as the micronaire chamber  28  into which the plug  18  will be loaded for measurement of the micronaire readings. For example, in the depicted embodiment, the micronaire chamber  28  has a generally circular cross-sectional shape, and thus the loader  12  preferably forms the fiber sample  18  into a plug  18  having a generally circular cross-sectional shape. 
         [0030]    To accomplish this, an interior lateral wall  20  of the loader  12  has a rounded bottom corner, to approximate the interior of the micronaire chamber  28  at that equivalent location. Similarly, the exterior lateral wall  22  of the loader  12  also has a rounded bottom corner, again to approximate the interior of the micronaire chamber  28  at that equivalent location. It is appreciated that if the micronaire chamber  28  has a different cross-sectional shape, the elements described would preferably have different shapes than those described herein, which different shapes are again selected so as to approximate the equivalent locations of the micronaire chamber  28 . Thus, the desired function is the substantial pre-formation of the fiber sample  18  into a plug  18  that has the general shape of the micronaire chamber  28 . 
         [0031]    As depicted in the  FIG. 2 , and according to the configuration of the present example, the exterior lateral wall  22  of the loader  12  is brought toward the interior lateral wall  20  of the loader  12 , thus laterally forming the fiber sample  18  into the shape of the micronaire chamber  28 . More specifically, the bottom portion of the fiber sample  18  is formed into the shape of the micronaire chamber  28 , by the two rounded bottom corners of the interior lateral wall  20  and the exterior lateral wall  22  that have been brought together. 
         [0032]    As depicted in  FIG. 2 , the top formation member  24  preferably also has elements that assist in forming the fiber sample  18  into the shape of the micronaire chamber  28 . In the example depicted, the top formation member  24  has a rounded interior surface, to approximate the interior of the micronaire chamber  28  at that equivalent location. 
         [0033]    As depicted in  FIG. 3 , the top formation member  24  is brought down onto the fiber sample  18 , to complete the formation of the fiber sample  18  into the shape of the micronaire chamber  28 . It is appreciated that the order of the compaction by which the fiber sample  18  is formed into a plug  18  with the same cross-sectional shape as the micronaire chamber  28  is by way of example only, and that in various embodiments the plug  18  can be vertically shaped first and then laterally shaped, or the shaping members can be oriented into a configuration that is something other than orthogonal. All such configurations are within the contemplated scope of the present invention. 
         [0034]    Also depicted in  FIG. 3  is the forward plunger  26 , which preferably also is configured to have a cross-sectional shape that is substantially equivalent to the cross-sectional shape of the micronaire chamber  28 . As depicted in  FIG. 3 , the forward plunger  26  is preferably perforated, for purposes as described in more detail hereafter. 
         [0035]      FIG. 4  depicts the loader  12  where the forward plunger  26  has been extended, thus driving the fiber sample  18 , which has been formed by the loader into substantially the shape of the micronaire chamber  28 , from the loader  12  and into the micronaire chamber  28 . In alternate embodiments, however, the loader  12 , after being configured to compact the fiber sample  18 , then becomes the micronaire chamber  28 , and no separate micronaire chamber  28  is required. In such an embodiment, the various moving elements of the loader  12  are preferably fashioned from materials that form substantially air-tight seals at the interfaces between them, or are fitted with edge moldings of such material. 
         [0036]    As depicted in  FIG. 5 , in those embodiments where there is a separate micronaire chamber  28  into which the forward plunger  26  drives the fiber sample that has been pre-formed into a plug  18 , the plug  18  meets the rear plunger  30  at the back of the micronaire chamber  28 , and begins to be compacted in its length between the forward plunger  26  and the rear plunger  30  as the forward plunger  26  moves forward. In alternate embodiments, the forward plunger  26  can be brought to a point in the micronaire chamber  28  where the plug  18  has not yet compacted, and then the rear plunger  30  can be moved to compact the plug  18  against the forward plunger  26 . Various other embodiments are also within the scope of this disclosure, such as where both plungers  26  and  30  move toward each other, or move in the same direct at differing speeds that produce a compaction of the fibers in the plug  18 . 
         [0037]    The methods by which the apparatus  10  takes the micronaire measurements are described in more detail hereafter. After the micronaire measurements have been taken on the plug  18 , the plug  18  is preferably expelled from the apparatus  10 . This can be accomplished be either withdrawing one of the forward plunger  26  and the rear plunger  30 , and using the other plunger to expel the plug  18  from one or both of the micronaire chamber  28  or the loader  12 . Alternately, and especially in those embodiments where the loader  12  comprises the micronaire chamber  28 , the combined loader  12 —micronaire chamber  28  can be opened up and the plug  18  can be withdrawn, either by gravity or some other means. 
         [0038]      FIG. 6  depicts an embodiment where the rear plunger  30  is withdrawn from the back of the bore of the micronaire chamber  28 , and the forward plunger  26  pushes the plug  18  out the back of the bore of the micronaire chamber  28 . The plug  18 , similar to that as described in alternate embodiments above, can either fall from the micronaire chamber  28  or be withdrawn by some other removal means, such as a mechanical device or a vacuum-induced air flow. 
         [0039]    In the preferred embodiment, the fiber sample  18  is weighed as a part of the micronaire measurement. Although the weight of the sample can be approximated in a variety of different ways, it has been determined that actually weighing the fiber sample  18  tends to produce more accurate micronaire readings. Weighing the fiber sample  18  can be accomplished either before or after the fiber sample  18  is formed into a plug  18  by the loader  12 , and either before or after the plug  18  is processed in the micronaire chamber  28 . 
         [0040]    If the weight of the fiber sample  18  is not measured until after the micronaire measurements are taken in the micronaire chamber  28 , such as after the plug  18  has been expelled from the micronaire chamber  28 , then an actual micronaire reading might not be presented until after the fiber sample  18  has been weighed. Alternately, various means can be used to estimate the weight of the fiber sample  18 , and those estimates can be used to provide a calculated micronaire reading for the fiber sample  18 . Further yet, an estimated weight can be used for a preliminary calculation, which is then fine-tuned by the use of the actual weight of the fiber sample  18  after it has been weighed. 
       Micronaire Measurement 
       [0041]    The apparatus  10  described above can be used in a variety of different ways to take micronaire readings.  FIG. 7  depicts a functional block diagram of portions of the apparatus  10 , which will be used to describe the micronaire measurements. In taking micronaire measurements, several parameters are preferably known, including the weight of the fiber sample  18 , the volume of the portion of the micronaire chamber  28  in which the tests are conducted, the volumetric rate of the air flow that enters  32  and exits  34  the micronaire chamber  28 , and the pressure differential within the micronaire chamber  28  as measured on a pressure differential meter  40  between an upstream pressure port  36  and a downstream pressure port  38 . Information such as this is used in the equations as given above to calculate the micronaire of the fiber sample  18 . 
         [0042]    Preferably, the fiber sample  18  is compacted within the micronaire chamber  28  to a relatively consistent degree between the forward plunger  26  and the rear plunger  30 , for all micronaire readings. Thus, if the fiber sample  18  has been weighed prior to testing, the volume of the micronaire chamber  28  can be set by bringing the forward plunger  26  and the rear plunger  30  relatively toward each other to form a volume that is based on the weight of the fiber sample  18  and an assumed density of the fiber sample  18 . 
         [0043]    If the fiber sample  18  has not been weighed prior to taking the readings, or if the weight of the fiber sample  18  is otherwise not to be used to determine the desired degree of compaction, then the desired degree of compaction can be set by turning on the air flow  32 , and reducing the distance between the forward plunger  26  and the rear plunger  30  in a controlled manner, preferably such as at a constant velocity. This can be accomplished with stepper motors that drive one or both of the forward plunger  26  and the rear plunger  30 . Various elements of the air flow properties of the air flow  32  are then monitored, which measured properties are then used to determine the desired micronaire chamber  28  length. Properties of the air flow  32  such as the volumetric flow and the pressure of the air flow  32 / 34  are generally referred to as air flow properties. 
         [0044]    For example, the volumetric flow of the air flow  32  as delivered at a constant inlet pressure can be measured, and when the flow rate falls to a desired value, then the relative movement of the plungers  26  and  30  is stopped. Alternately, the air flow  32  is initiated, and as the degree of compaction increases the air flow resistance through the compacting fiber sample  18 , the air flow decreases and the pressure increases. Either the reduction in the air flow or the increase in the pressure can be measured, and the plunger movement can be stopped when a desired set point is attained. In yet another alternate embodiment, a constant volumetric flow of the air flow  32  can be initiated, while the pressure required to produce the constant volumetric flow is measured. When the pressure required to produce the constant volumetric flow rises to a determined level, then the relative movement of the plungers  26  and  30  is stopped. 
         [0045]    These air flow properties as monitored provide an indication of the degree of resistance to the air flow  32 / 34  through the compacted fiber sample  18 , which in turn provides an indication of the degree of compaction of the fiber sample  18 . At this point the distance between the plungers  26  and  30  is determined, so that the volume of the micronaire chamber  28  is known. The distance between the plungers  26  and  30  can be directly measured, sensed along the length of the micronaire chamber  28 , or determined by tracking the progress of the stepper motors that drive one or both of the plungers  26  and  30 . 
         [0046]    The volume of the micronaire chamber  28  when a desired degree of compaction of the fiber sample  18  has been attained can also be used to estimate the weight of the fiber sample  18  within the micronaire chamber  28 . In some embodiments this estimated weight of the fiber sample  18  is sufficient. However, if more accurate micronaire values are desired, then the fiber sample  18  is preferably weighed at some point before, during, or after the measurement process. 
         [0047]    The micronaire chamber  28  preferably has an operable length of up to about six inches in which micronaire testing can be performed on a compacted fiber sample  18 , so as to accommodate a wide range of fiber sample  18  weights. In this manner, the means by which the loader  12  is loaded with the fiber sample  18  does not need to be too sensitive in regard to the amount of the fiber sample  18  that is so loaded. Preferably the diameter of the bore of the micronaire chamber  28  is selected so that the length specified above can hold between about one and about ten grams of a cotton fiber sample  18 . 
         [0048]    The foregoing description of preferred embodiments for this invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Obvious modifications or variations are possible in light of the above teachings. The embodiments are chosen and described in an effort to provide the best illustrations of the principles of the invention and its practical application, and to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled.