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.

FIELD

Background

Micronaire readings are derived from Koxeny'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:

where, over a sample weight range of about eight grams to about twelve grams:

HMC=High calibration cotton value

LMC=Low calibration cotton value

LMP=Pressure of low calibration cotton value

HMP=Pressure of high calibration cotton value

P=Pressure of cotton under test

W=Weight of cotton under test, grams

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.

What is needed, therefore, is a system for measuring micronaire that provides benefits, such as those mentioned above, at least in part.

SUMMARY

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.

In this manner, there is provided a convenient method of setting a testing volume and acquiring the information needed to take a micronaire measurement.

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.

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.

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.

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.

DETAILED DESCRIPTION

Sample Loading and Unloading

With reference now toFIG. 1, there is depicted a micronaire measurement system10according to a preferred embodiment of the present invention. As depicted inFIG. 1, the sample loading mechanism12is in the sample reception position, with the lateral plug formation member14and the vertical plug formation member16extended. With the loader12in this position, the loader12is adapted to receive the fiber sample18, on which micronaire measurements are to be made. The fiber sample18may be any one or blend of more than one fiber types, but in the preferred embodiment the fiber sample18is cotton fiber.

The various elements of the loader12are preferably adapted so as to form the fiber sample18into a plug18that is substantially the same cross-sectional shape as the micronaire chamber28into which the plug18will be loaded for measurement of the micronaire readings. For example, in the depicted embodiment, the micronaire chamber28has a generally circular cross-sectional shape, and thus the loader12preferably forms the fiber sample18into a plug18having a generally circular cross-sectional shape.

To accomplish this, an interior lateral wall20of the loader12has a rounded bottom corner, to approximate the interior of the micronaire chamber28at that equivalent location. Similarly, the exterior lateral wall22of the loader12also has a rounded bottom corner, again to approximate the interior of the micronaire chamber28at that equivalent location. It is appreciated that if the micronaire chamber28has 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 chamber28. Thus, the desired function is the substantial pre-formation of the fiber sample18into a plug18that has the general shape of the micronaire chamber28.

As depicted in theFIG. 2, and according to the configuration of the present example, the exterior lateral wall22of the loader12is brought toward the interior lateral wall20of the loader12, thus laterally forming the fiber sample18into the shape of the micronaire chamber28. More specifically, the bottom portion of the fiber sample18is formed into the shape of the micronaire chamber28, by the two rounded bottom corners of the interior lateral wall20and the exterior lateral wall22that have been brought together.

As depicted inFIG. 2, the top formation member24preferably also has elements that assist in forming the fiber sample18into the shape of the micronaire chamber28. In the example depicted, the top formation member24has a rounded interior surface, to approximate the interior of the micronaire chamber28at that equivalent location.

As depicted inFIG. 3, the top formation member24is brought down onto the fiber sample18, to complete the formation of the fiber sample18into the shape of the micronaire chamber28. It is appreciated that the order of the compaction by which the fiber sample18is formed into a plug18with the same cross-sectional shape as the micronaire chamber28is by way of example only, and that in various embodiments the plug18can 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.

Also depicted inFIG. 3is the forward plunger26, which preferably also is configured to have a cross-sectional shape that is substantially equivalent to the cross-sectional shape of the micronaire chamber28. As depicted inFIG. 3, the forward plunger26is preferably perforated, for purposes as described in more detail hereafter.

FIG. 4depicts the loader12where the forward plunger26has been extended, thus driving the fiber sample18, which has been formed by the loader into substantially the shape of the micronaire chamber28, from the loader12and into the micronaire chamber28. In alternate embodiments, however, the loader12, after being configured to compact the fiber sample18, then becomes the micronaire chamber28, and no separate micronaire chamber28is required. In such an embodiment, the various moving elements of the loader12are preferably fashioned from materials that form substantially air-tight seals at the interfaces between them, or are fitted with edge moldings of such material.

As depicted inFIG. 5, in those embodiments where there is a separate micronaire chamber28into which the forward plunger26drives the fiber sample that has been pre-formed into a plug18, the plug18meets the rear plunger30at the back of the micronaire chamber28, and begins to be compacted in its length between the forward plunger26and the rear plunger30as the forward plunger26moves forward. In alternate embodiments, the forward plunger26can be brought to a point in the micronaire chamber28where the plug18has not yet compacted, and then the rear plunger30can be moved to compact the plug18against the forward plunger26. Various other embodiments are also within the scope of this disclosure, such as where both plungers26and30move toward each other, or move in the same direct at differing speeds that produce a compaction of the fibers in the plug18.

The methods by which the apparatus10takes the micronaire measurements are described in more detail hereafter. After the micronaire measurements have been taken on the plug18, the plug18is preferably expelled from the apparatus10. This can be accomplished be either withdrawing one of the forward plunger26and the rear plunger30, and using the other plunger to expel the plug18from one or both of the micronaire chamber28or the loader12. Alternately, and especially in those embodiments where the loader12comprises the micronaire chamber28, the combined loader12—micronaire chamber28can be opened up and the plug18can be withdrawn, either by gravity or some other means.

FIG. 6depicts an embodiment where the rear plunger30is withdrawn from the back of the bore of the micronaire chamber28, and the forward plunger26pushes the plug18out the back of the bore of the micronaire chamber28. The plug18, similar to that as described in alternate embodiments above, can either fall from the micronaire chamber28or be withdrawn by some other removal means, such as a mechanical device or a vacuum-induced air flow.

In the preferred embodiment, the fiber sample18is 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 sample18tends to produce more accurate micronaire readings. Weighing the fiber sample18can be accomplished either before or after the fiber sample18is formed into a plug18by the loader12, and either before or after the plug18is processed in the micronaire chamber28.

If the weight of the fiber sample18is not measured until after the micronaire measurements are taken in the micronaire chamber28, such as after the plug18has been expelled from the micronaire chamber28, then an actual micronaire reading might not be presented until after the fiber sample18has been weighed. Alternately, various means can be used to estimate the weight of the fiber sample18, and those estimates can be used to provide a calculated micronaire reading for the fiber sample18. 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 sample18after it has been weighed.

The apparatus10described above can be used in a variety of different ways to take micronaire readings.FIG. 7depicts a functional block diagram of portions of the apparatus10, which will be used to describe the micronaire measurements. In taking micronaire measurements, several parameters are preferably known, including the weight of the fiber sample18, the volume of the portion of the micronaire chamber28in which the tests are conducted, the volumetric rate of the air flow that enters32and exits34the micronaire chamber28, and the pressure differential within the micronaire chamber28as measured on a pressure differential meter40between an upstream pressure port36and a downstream pressure port38. Information such as this is used in the equations as given above to calculate the micronaire of the fiber sample18.

Preferably, the fiber sample18is compacted within the micronaire chamber28to a relatively consistent degree between the forward plunger26and the rear plunger30, for all micronaire readings. Thus, if the fiber sample18has been weighed prior to testing, the volume of the micronaire chamber28can be set by bringing the forward plunger26and the rear plunger30relatively toward each other to form a volume that is based on the weight of the fiber sample18and an assumed density of the fiber sample18.

If the fiber sample18has not been weighed prior to taking the readings, or if the weight of the fiber sample18is 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 flow32, and reducing the distance between the forward plunger26and the rear plunger30in 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 plunger26and the rear plunger30. Various elements of the air flow properties of the air flow32are then monitored, which measured properties are then used to determine the desired micronaire chamber28length. Properties of the air flow32such as the volumetric flow and the pressure of the air flow32/34are generally referred to as air flow properties.

For example, the volumetric flow of the air flow32as 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 plungers26and30is stopped. Alternately, the air flow32is initiated, and as the degree of compaction increases the air flow resistance through the compacting fiber sample18, 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 flow32can 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 plungers26and30is stopped.

These air flow properties as monitored provide an indication of the degree of resistance to the air flow32/34through the compacted fiber sample18, which in turn provides an indication of the degree of compaction of the fiber sample18. At this point the distance between the plungers26and30is determined, so that the volume of the micronaire chamber28is known. The distance between the plungers26and30can be directly measured, sensed along the length of the micronaire chamber28, or determined by tracking the progress of the stepper motors that drive one or both of the plungers26and30.

The volume of the micronaire chamber28when a desired degree of compaction of the fiber sample18has been attained can also be used to estimate the weight of the fiber sample18within the micronaire chamber28. In some embodiments this estimated weight of the fiber sample18is sufficient. However, if more accurate micronaire values are desired, then the fiber sample18is preferably weighed at some point before, during, or after the measurement process.

The micronaire chamber28preferably has an operable length of up to about six inches in which micronaire testing can be performed on a compacted fiber sample18, so as to accommodate a wide range of fiber sample18weights. In this manner, the means by which the loader12is loaded with the fiber sample18does not need to be too sensitive in regard to the amount of the fiber sample18that is so loaded. Preferably the diameter of the bore of the micronaire chamber28is selected so that the length specified above can hold between about one and about ten grams of a cotton fiber sample18.