Patent EP-1058085-A2 (EP)
Inventor: STEIN WOLFGANG DR
IPC: G01N3/08
Filed: 2000-05-20
Abstract: The appts. to measure the stretch or contraction characteristics of a test yarn has a positioning unit (24) to site the test yarn (10) in relation to the heater (18) or the heater (18) in relation to the test yarn (10) within the housing (2), at the test stretch (12) between the yarn feed/take-off units (4,8), containing the force measurement monitor (14). In one setting the test yarn (10) is outside the heater (18) and, in the other end setting, it is within the heater. The upper temp. limit of the heater (18) is set at 260-800 degrees C. The heater (18) has a longitudinal heating channel (19) to hold the test yarn (10). The heater housing (17) has a slit (20) to insert the test yarn (10) into the channel (19). The slit (20) can be closed. Additional monitors (26,28) are between the yarn feed (4) and take-off (8) units, or they are in front of the feed (4) or after the take-off (8) in the direction of yarn movement. The monitors (26,28) register the friction or filament breaks, yarn eddy points, bulk vol. of texturized yarns, yarn irregularities or the yarn thickness. A yarn tensioner (22) is in front of the yarn feed unit (4), in the direction of yarn travel, to set and maintain a given test yarn (10) tension, controlled by the force measurement monitor (14). A thermal sensor (30) is after the heater (18), in the direction of yarn travel, to register the temp. of the test yarn (10) after heating. A twister (34), after the heater (18), imposes a false twist on the test yarn (10). The yarn movement speeds at the yarn feed (4) and take-off (8) differ from each other, set by a program control. By a continual shift in the yarn speed ratios between the feed (4) and take-off (8), a constant draw force on the test yarn (10) can be set and adjusted. The speed control uses the measurement signal from the force measurement monitor (14) with simultaneous measurement of the movement speed ratio. On a given movement speed ratio, the yarn feed (4) is set to give a constant test yarn (10) length change with simultaneous measurement of the draw force. To give a dynamic force elongation curve, the variable stretch imposed on the test yarn (10) is program controlled with simultaneous measurement of the draw force. The temp. of the heater (18) is variable and program controlled during the measurements of the draw force or yarn length change. The assembly can have three yarn transport units (4,8), forming two test stretches between them for the test yarn (10). Each test stretch has its own heater and separate force measurement monitor. An Independent claim is included for a yarn stretch test where an initial yarn tension is set at the test yarn (10). The test yarn (10) is moved in relation to a heater (18) or the heater (18) is moved in relation to the test yarn (10), and the yarn (10) is passed to the heater (18) which has been heated or still at room temp. The yarn is tested for the draw force and length change by measurement of the change in the test yarn (10) length with a constant draw force or the draw force is measured on a constant preset stretch at the test yarn (10). Preferred Features: A constant stretch at the test yarn (10) is set by a fixed movement speed ratio between the yarn speeds at the transport units (4,8), and the draw force is measured. To measure dynamic force elongation curves, the stretch values are altered in steps or continuously. A constant yarn draw force is set by adjustments to the speed ratio between the two yarn transport units (4,8), and the yarn stretch is measured. The speed ratio is controlled by the force measurement signal. On separation of the test stretch (12) into two successive sections, each test section is heated differently so that an initial test yarn (10) drawing action is measured in the first section and a final drawing action is measured at the second section.