GB2031960A - Apparatus for measuring remanent torque in yarns - Google Patents

Abstract

The yarn 3 is clamped at 2 and a disc 4 is suspended from the lower end of the length of yarn. The length under a pre-tensioning weight 15 is fixed by a marker 5. The disc 4 rotates due to the remanent torque and the rotations to the first change of direction are automatically measured by means of a counter circuit connected to photo-electric detectors 8 illuminated through a radial slot in the disc 4 by lamps 7. A housing 1 encloses the apparatus and prevents disturbance by air currents. <IMAGE>

Description

SPECIFICATION Apparatus for measuring remanent torque in yarns The present invention relates to apparatus for automatic testing or torsional equilibrium in yarns.

During the processing of twisted or doubled yarns, difficulties often occur as a result of kinkless break- ages on the machines, due to the lack of equilibrium created by the existence in the yarn of a remanent torque. This torque may exceed certain admissible limits as a consequence of an inadequate twist set degree or doubling.

The known equipment for measuring the rema nenttorque generally has a frame with a fastening clamp for a length of th read on which a weight is suspended. An operator then observes with the naked eye the number of rotations which occur before the first change of the direction of rotation. If the rotation is too fast the operator is unable to follow it and this will result in errors. The operator has to be present throughout the test, which may take 4 to 5 hours. The operator therefore suffers severely from visual fatigue, which again may result in errors.

There is no protection of the thread undertest against disturbing currents. Finally there is no provision for pre-twisting the yarn to establish a constant yarn length.

In accordance with the present invention there is provided apparatus for measuring remanent torque in yarns comprising an enclosed housing, clamps for the yarn at the upper end of the housing a disc suspendable from the lower end of the yarn to be measured to rotate about its principle axis under the influence of the remanent torque, the disc having a radial slot, and light sources and photo-electric transducers mounted in the housing on opposite sides of the disc position such that the slot in the disc intermittently allows light to fall on the transducers as the disc rotates.

This apparatus allows automatic counting of the number of rotations and also by the use of appropriate circuit logic allows automatic detection of the direction of rotation and any change in that direction. An electronic circuit connected to the transducers preferably comprises an amplifier for shaping and amplifying pulses from the transducers, a logic circuit, and a counter and display unit. The logic circuit may include a gating device for blocking the passage of pulses to the counter and display unit when the direction of rotation of the disc changes. A commutating device is preferably provided to allow for testing of yarns of both S and Z twist.

The invention will now be described in more detail with the aid of an example illustrated in the accompanying drawings, in which: Figure 1 is a vertical section of apparatus in accordance with the invention; Figure 2 shows a detail of Figure 1 in elevation and in plan view; and Figure 3 is a block circuit diagram of an electronic circuit for us in conjunction with the apparatus of Figure 1.

The apparatus shown in Figure 1 comprises an enclosed housing 1 having two clamps 2 at its upper end for securing the yarn 3. The yarn is drawn from a bobbin and forms a loop hanging down within the housing 1. A disc 4 is attached to the lower end of the loop yarn, whose length from the clamps 2 is indi cated by a reference marker 5 attached to the housing 1. A holder 6 supports the disc 4 within a working compartment 4. Light sources 7 are disposed in a compartment B above the compartment A and photoelectric transducers 8 are disposed in a compartment C below the compartment A.

Turning to Figure 3 it will be seen that signals from the photo-electric transducers 8 are shaped and amplified by an amplifier 9, processed by a logic unit 10 which includes a gating circuit and has a release button 11, and transmitted to a counter and display unit 12. As shown, these components of the electronic circuit are all fed from a stabilized voltage source 5.

The disc4 (Figure 2) has a hook 13 on its upper side for attachment to the yarn loop and a loop 14 on its lower side to carry a pre-tensioning weight 15. The loop 14 also cooperates with the holder 6 to prevent rotation of the disc 4 while the apparatus is being set up. The disc 4 has an opening in the form of a radial slota which controls the passage of light from the lamps 7 to the transducers 8 when the disc is rotating.

When a measurment is to be made the yarn 3 to be measured is fixed between th clamps 2 and the hook 13 and has a length determined by reference to the marker 5. The disc 4 is at this time held against rotation but the yarn may be streached by pre-tensioning weights 15. The light sources 7 and the electronic circuit are connected to the electrical supply. The disc4 is now freed from the holder 6 and at the same time the electronic circuit is released by the release button 11. In consequence of the remanenttorque in the yarn 3 the disc 4 starts to rotate and the passage of the slot a between the light sources 7 and the transducers 8 generates electrical signals which are processed by the amplifier 9 and logic unit 10 and displayed by the counter and display unit 12.The provision of three transducers 8 unequally spaced around the axis of rotation allows the direction of rotation to be determined and in particular provides an indication of a change in the direction of rotation of the disc 4. When this occurs the passage of further pulses to the counter is blocked.

The electronic circuit has a commutator 16 which can be switched over to allow for different directions of twist in the yarn.

The apparatus described has the following advantages: - it allows high-precision measurement of the number of rotations no matter what the degree of torsional disequilibrium oftheyarn may be and what the consequent speed of rotation may be; - it allows the initial length of the yarn to be tested to be correctly established because weights can be hung on the disc corresponding to the nominal fineness of the yarn; - the yarn is protected against air currents by the housing; and - the presence of the operator is not required throughout the length of the test.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Apparatus for measuring remanent torque in yarns The present invention relates to apparatus for automatic testing or torsional equilibrium in yarns. During the processing of twisted or doubled yarns, difficulties often occur as a result of kinkless break- ages on the machines, due to the lack of equilibrium created by the existence in the yarn of a remanent torque. This torque may exceed certain admissible limits as a consequence of an inadequate twist set degree or doubling. The known equipment for measuring the rema nenttorque generally has a frame with a fastening clamp for a length of th read on which a weight is suspended. An operator then observes with the naked eye the number of rotations which occur before the first change of the direction of rotation. If the rotation is too fast the operator is unable to follow it and this will result in errors. The operator has to be present throughout the test, which may take 4 to 5 hours. The operator therefore suffers severely from visual fatigue, which again may result in errors. There is no protection of the thread undertest against disturbing currents. Finally there is no provision for pre-twisting the yarn to establish a constant yarn length. In accordance with the present invention there is provided apparatus for measuring remanent torque in yarns comprising an enclosed housing, clamps for the yarn at the upper end of the housing a disc suspendable from the lower end of the yarn to be measured to rotate about its principle axis under the influence of the remanent torque, the disc having a radial slot, and light sources and photo-electric transducers mounted in the housing on opposite sides of the disc position such that the slot in the disc intermittently allows light to fall on the transducers as the disc rotates. This apparatus allows automatic counting of the number of rotations and also by the use of appropriate circuit logic allows automatic detection of the direction of rotation and any change in that direction. An electronic circuit connected to the transducers preferably comprises an amplifier for shaping and amplifying pulses from the transducers, a logic circuit, and a counter and display unit. The logic circuit may include a gating device for blocking the passage of pulses to the counter and display unit when the direction of rotation of the disc changes. A commutating device is preferably provided to allow for testing of yarns of both S and Z twist. The invention will now be described in more detail with the aid of an example illustrated in the accompanying drawings, in which: Figure 1 is a vertical section of apparatus in accordance with the invention; Figure 2 shows a detail of Figure 1 in elevation and in plan view; and Figure 3 is a block circuit diagram of an electronic circuit for us in conjunction with the apparatus of Figure 1. The apparatus shown in Figure 1 comprises an enclosed housing 1 having two clamps 2 at its upper end for securing the yarn 3. The yarn is drawn from a bobbin and forms a loop hanging down within the housing 1. A disc 4 is attached to the lower end of the loop yarn, whose length from the clamps 2 is indi cated by a reference marker 5 attached to the housing 1. A holder 6 supports the disc 4 within a working compartment 4. Light sources 7 are disposed in a compartment B above the compartment A and photoelectric transducers 8 are disposed in a compartment C below the compartment A. Turning to Figure 3 it will be seen that signals from the photo-electric transducers 8 are shaped and amplified by an amplifier 9, processed by a logic unit 10 which includes a gating circuit and has a release button 11, and transmitted to a counter and display unit 12. As shown, these components of the electronic circuit are all fed from a stabilized voltage source 5. The disc4 (Figure 2) has a hook 13 on its upper side for attachment to the yarn loop and a loop 14 on its lower side to carry a pre-tensioning weight 15. The loop 14 also cooperates with the holder 6 to prevent rotation of the disc 4 while the apparatus is being set up. The disc 4 has an opening in the form of a radial slota which controls the passage of light from the lamps 7 to the transducers 8 when the disc is rotating. When a measurment is to be made the yarn 3 to be measured is fixed between th clamps 2 and the hook 13 and has a length determined by reference to the marker 5. The disc 4 is at this time held against rotation but the yarn may be streached by pre-tensioning weights 15. The light sources 7 and the electronic circuit are connected to the electrical supply. The disc4 is now freed from the holder 6 and at the same time the electronic circuit is released by the release button 11. In consequence of the remanenttorque in the yarn 3 the disc 4 starts to rotate and the passage of the slot a between the light sources 7 and the transducers 8 generates electrical signals which are processed by the amplifier 9 and logic unit 10 and displayed by the counter and display unit 12.The provision of three transducers 8 unequally spaced around the axis of rotation allows the direction of rotation to be determined and in particular provides an indication of a change in the direction of rotation of the disc 4. When this occurs the passage of further pulses to the counter is blocked. The electronic circuit has a commutator 16 which can be switched over to allow for different directions of twist in the yarn. The apparatus described has the following advantages: - it allows high-precision measurement of the number of rotations no matter what the degree of torsional disequilibrium oftheyarn may be and what the consequent speed of rotation may be; - it allows the initial length of the yarn to be tested to be correctly established because weights can be hung on the disc corresponding to the nominal fineness of the yarn; - the yarn is protected against air currents by the housing; and - the presence of the operator is not required throughout the length of the test. CLAIMS

1. Apparatus for measuring remanent torque in yarns comprising an enclosed housing, clamps for the yarn at the upper end of the housing a disc suspendable from the lower end of the yarn to be measured to rotate about its principle axis under the influence of the remanenttorque, the disc having a radial slot, and light sources and photo-electrictransduc- ers mounted in the housing on opposite sides of the disc position such that the slot in the disc intermittently allows light to fall on the transducers as the disc rotates.

2. Apparatus as claimed in claim 1 in which the housing has a first compartment to accommodate the disc, a second compartment containing the light sources and a third compartment containing the transducers.

3. Apparatus as claimed in claim 1 or2 including an electronic circuit connected to the transducers and comprising an amplifier, a logic circuit, and a counter and display unit.

4. Apparatus as claimed in claim 3 in which the logic circuit includes a gating device for blocking the passage of pulses to the counter and display unit when the direction of rotation of the disc changes.

5. Apparatus for measuring remanenttorque in yarns substantially as described with reference to the accompanying drawings.