AU2005286052A1

AU2005286052A1 - Method and equipment for determining fibre fineness

Info

Publication number: AU2005286052A1
Application number: AU2005286052A
Authority: AU
Inventors: Unnikrishna Vinod Kurup
Original assignee: UNNIKRISHNA KURUP
Current assignee: UNNIKRISHNA KURUP
Priority date: 2004-09-20
Filing date: 2005-09-12
Publication date: 2006-03-30
Also published as: WO2006033116A1

Description

WO 2006/033116 PCT/IN2005/000306 1 DESCRIPTION METHOD AND EQUIPMENT FOR DETERMINING FIBRE FINENESS TECHNICAL FIELD This invention relates to a method and equipment for determining fibre fineness. One significant quality parameter in the specification of a fibre is its fineness. Fibre fineness can be expressed in different ways. In the case of a cotton fibre, the fineness is expressed using a term called 'micronaire' which is nothing but the weight in micrograms of one inch (25.4 millimeters) length of the fibre. In the case of wool fibres and other fibres, fineness is expressed by a parameter called 'micron value' which is nothing but the fibre diameter in micrometers. BACKGROUND ART In the known art fibre fineness can be determined by using different techniques. A fundamental method of determining cotton fibre fineness is to cut fibres of one inch (25.4 millimeters) length and weigh each of them. The weight in micrograms of one inch (25.4 millimeters) of a fibre gives its fineness in 'micronaire'. A number of readings can be taken and the average micronaire estimated. A basic method of determining wool fiber fineness is by preparing a cross section of several wool fibres on a glass slide and putting the same under a microscope with graduated markings and measuring the wool fibre diameter of each fibre and then calculating the average fibre diameter in microns. A popular method of determining fineness of fibres is by using an air flow instrument which works on the method of estimating the inter relationship between the pressure of air across a plug of fibre, the flow rate of air across the plug of fibre and the fineness of the fibre when air is passed through a plug of fibre. In this method an external pump forces air at a constant pressure through a plug of fibre of unknown fineness compressed inside a perforated chamber. The flow rate of air passing through the plug of fibre will depend upon its fineness since the surface area of the fibre mass offering resistance to air flow depends upon the fibre fineness. The flow rate of air passing through the fibre is determined by using a rotameter or any other flow rate measuring device. In a rotameter the position of a float in a vertical, conical, graduated and transparent tube will depend on WO 2006/033116 PCT/IN2005/000306 2 the flow rate of air passing through the same and this is initially calibrated to give the fibre fineness in microns or micronaire value by using fibres of known fineness (estimated using other methods). An alternate method based on the above mentioned interrelationship is to pass air at a constant flow rate across the plug of fibre and measure the pressure difference of air across the plug of fibre. This pressure difference will vary depending upon the fibre fineness since varying fibre fineness means varying surface area of fibres. This pressure difference of air across the fibre of unknown fineness can be measured by using a manometer or electronic pressure sensor and this pressure difference is initially calibrated to directly give fibre fineness by using fibres of known fineness (estimated using other methods). Another known art is the use of modem electronic microscopes which will electronically capture the image of the fibre and then measure the same. Yet another known art is the use of a laser beam and the light scattering property of fibres to determine its fineness. INVENTION AND DESCRIPTION OF DRAWINGS The invention is based on a novel method of passing air through a plug of fibre in a novel equipment and using an interrelationship not previously used namely those between volume of air passing though a plug of fibre , time taken for this volume to pass through the plug of fibre and the fibre fineness. The invention can be best understood by looking at the enclosed figure. '1' shows a long vessel containing a liquid say water up to say half its height the level being indicated as '2'. In this vessel, an inverted vessel '3' can go up and down. On top of the inverted vessel is a chamber '4'. This chamber has a bottom '5' containing perforated holes and a plug '6' which also contains perforated holes at its bottom '7'. The plug compresses and locks a predefined mass of fibres '8' put into the chamber to predefined dimensions. There are two references points 'a' and 'b' on the side of the vessel '1' at predefined heights. The inverted vessel '3' containing the fibre under test is lifted so that a reference point 'c' on it is at a height more than the reference point 'a' and then released. The inverted vessel slowly starts sinking into the water and the air entrapped inside it passes through the plug of fibre. The inverted vessel does the important function to allow the entrapped air in it to pass through the plug of fibre only. The time taken for the reference WO 2006/033116 PCT/IN2005/000306 3 point 'c' to pass the two reference points 'a' and 'b' is noted. This is the time taken for a constant volume of air to pass through the fibre plug depending upon the dimensions of the equipment and the distance between 'a' and 'b'. The time depends upon the fineness of the fibre under test. The equipment is calibrated using different fibres of known fineness (tested using other methods). The time taken for the constant volume of air to pass through the plug of fibre can be determined by using a manual stop watch, or an automatic time recorder based on mechanical tripper switching when an object at 'c' passes over switching devices placed at 'a' and 'b'. The automated time recorder can also be constructed using other devices like photo electric switches at 'a' and 'b' activated by a protrusion at 'c' passing through these points at the time of descent. The time recorder may be an electronic system or one exploiting the timer of a computer. The estimation of fibre fineness can also be either manual or automatic based on the time being fed to an elecronic computing system or a computer loaded with a prefed program to calculate the fibre fineness. Another mode of working this invention is to start a timer the moment the inner sinking vessel reference point 'c' reaches point 'a '. After a constant, predefined time is reached, immediately the height to which the inner vessel has sunk from point 'a' is noted. This height which is directly proportional to the volume of air that has passed through the fibre depends upon the fineness of the fibre under test and is calibrated to give fibre fineness by initially using fibres of known fineness (estimated using other techniques). The position of the sinking vessel after a constant time has elapsed can be noted by looking at a vertical scale placed between points 'a' and 'b' or by any other means of measuring this height including but not limited to electronic systems. The novelty and the difference between this invention and the air flow equipment used in the prior art is that in the prior art the interrelationship of three measurements namely pressure difference of air across a plug of fibre, flow rate of air across the plug of fibre and the fineness of the fibre is exploited to give fibre fineness whereas in this invention the technical relationship between a different set of measurements namely volume of air flow, time taken for air to flow and the fineness of the fibre is exploited to determine fibre fineness. Besides the above in the prior art air flow equipment for determining fibre fineness, an external air pump is required to pass air through the plug of fibre where as in this invention the equipment itself by the sinking of an inverted vessel in a liquid forces air to WO 2006/033116 PCT/IN2005/000306 4 pass through the plug of fibre. BEST MODE OF WORKING THE INVENTION The equipment is first calibrated as follows: A fibre of known fibre fineness and of a specified mass is taken and put inside the chamber '4' and then compressed using plug '6'into predefined dimensions. The inverted vessel '3' is lifted and then released and the time taken for it to sink inside water between reference points 'a' and 'b' is estimated by using automatic switches at the above points hooked to an electronic system or the timer of a computer. The above procedure is repeated for various fibres of known fineness belonging to the same group of fibres. From the time periods thus obtained, the relationship between time versus fibre fineness is found using the well known mathematical technique of curve fitting. The formula thus obtained is then programmed into the automated electronic system or the computer. Now the equipment is ready to find the fibre fineness of unknown fibre samples belong to the class or group of fibres for which the correlation mathematical formula was determined. The method of determining the fibres fineness of an unknown sample mentioned above is as follows: The specified weight (based on which the equipment was initially calibrated) of the unknown sample is taken and inserted into the empty test chamber '4' and then plugged using plug '6'. The Inverted vessel '3' is lifted so that point 'c' is well above reference point 'a' and then released. The inverted vessel '3' starts sinking. The electronic system or the timer of the computer automatically measures the time taken for the reference point 'c' to traverse the distance between 'a' and 'b'. This is the time taken for a constant volume of air based on the dimensions of the sinking cylinder and the distance between 'a' and 'b' to pass through the plug of fibre under test. This time is automatically fed In to the programmed formula and the fibre fineness is calculated and displayed by the electronic system or computer.

Claims

CLAIM/S

I claim

1) the method of determining fibre fineness by exploiting the relationship between a set of three different measurements namely volume of air flow, time taken for this air flow and fibre fineness when air is forced through a plug of fibre.

2) an equipment based upon the method described in claim 1) comprising of an inverted vessel having at its top a chamber with holes at the bottom for holding a plug of fibre and capable of sinking between two predefined heights in an outer vessel containing a liquid.

3) An equipment mentioned in claim 2) further characterised by the presence of a mechanical switching device connected to a time recorder which is started when the inner cylinder first starts sinking and reaches a particular height and then stops and records the time when the inner cylinder after some time sinks further and reaches another predefined height,.

4) An equipment mentioned in claim 2) further characterised by the presence of a photo electric switching device for recording the time taken for a constant volume of air to pass through the plug of fibre as the inner cylinder sinks from one height and reaches another predefined height.

5) An equipment mentioned in claim 3) or claim 4) further characterised by presence of an electronic system programmed to calculate the fibre fineness based on a correlation formula fed into it and the time recorded for a constant volume of air to pass through the plug of fibre under test.

6) An equipment mentioned in claim 2) further characterized by the presence of a scale between the two pre defined heights, graduated directly in fibre fineness and a pointer on the inverted vessel moving over the scale indicating fibre fineness when its position on the scale is noted after a predefined time has elapsed after the inner vessel has started sinking further down from the top predefined height.