GB1580299A

GB1580299A - Apparatus for twisting yarn while it is passed between a bobbin and a take-up package

Info

Publication number: GB1580299A
Application number: GB22623/78A
Authority: GB
Original assignee: Officine Savio SpA; Savio SpA
Current assignee: Officine Savio SpA; Savio SpA
Priority date: 1977-05-26
Filing date: 1978-05-25
Publication date: 1980-12-03
Also published as: DE7815652U1; DE2822758A1; CH626925A5; JPS5418940A; FR2391949A1

Abstract

The device for regulating the speed of winding of the yarn on bobbins in a twisting machine has a spindle rotation speed sensor (14) which sends a signal to a unit (18) for processing the signal sent from a selector of twists per unit length of the yarn (16). The signal (19) from the said processing unit (18) controls a yarn winding speed controller (20). The device can replace the various gears and lever mechanisms which determine the speed of winding on the bobbins and which have to be changed when variations in the number of twists per unit length are required according to the nature of the yarn and its application. <IMAGE>

Description

(54) APPARATUS FOR TWISTING YARN WHILE IT IS PASSED BETWEEN A BOBBIN AND A TAKE-UP PACKAGE (71) We, OFFICINE SAVIO S.P.A., of Via Udine, 33170 Pordenone, Italy, a Company organised and existing under the laws of Italy, do hereby declare the invention, for which we pray that a Patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to apparatus for twisting yarn while it is passed between a bobbin and a take-up package, and in particular to a twisting machine of the double twist variety.

It is known that in working yarn there is a need to take into consideration the nature of the yarn and its purpose when determining the number of twists per unit length.

It is therefore necessary to vary the speed at which the yarn is taken up into packages as a function of the required number of twists per unit length.

This has been done hitherto using mechanical servo devices. Gears or levers must be changed or substituted when the number of twists per unit length is changed, requiring a change of take-up speed.

Known machines have many inconveniences and disadvantages. One inconvenience is having to reset the take-up speed again and again whenever the number of twists per unit length is changed.

A further inconvenience is due to the limitation in number of the possible mechanical connections or gear ratios and consequently the lack of fine variation of the obtainable number of twists per unit length.

Furthermore there is also a drawback that in variable speed conditions, there may be at least temporarily a difference between the actual number of twists and the requested number of twists caused by slipping between the bobbins or packages and their drive shafts.

A principal object of the present invention is to overcome the above-mentioned drawbacks by providing apparatus which will regulate the take-up speed of the yarn collected by the packages in a continuous manner, the take-up speed being automatically determined dependent upon the rotational speed of the bobbins and the required twists per unit length of the yarn.

In accordance with the invention there is provided apparatus for twisting yarn while it is passed between a bobbin and a take-up package, wherein means is provided for automatically controlling the speed of rotation of the package as a function of a comparison between a first electrical signal proportional to the speed of rotation of the bobbin, or a control bobbin in tandem with said first-mentioned bobbin, and a second electrical signal proportional to a pre-selected number of twists per unit length imparted to the yarn as it passes between the bobbin and package.

The first electrical signal may be obtained from a transducer monitoring the speed of rotation of the bobbin, or control bobbin, and the first and second signals may be applied to a comparator the output signal of which is used to control a motor rotating the package.

A plurality of packages may be jointly rotated by a common spindle to receive twisted yarn from a plurality of bobbins mounted to be jointly rotated by a common drive shaft, and the speed of rotation of said common spindle may be controlled as a function of a comparison between said first and second signals. In this arrangement the first electrical signal may be obtained from a transducer connected to the common drive shaft, or from a transducer connected to an empty control bobbin mounted to be driven by said common drive shaft.

The speed of rotation of the take-up package, or common spindle,may be monitored by a transducer, and there may be interposed between the first-mentioned comparator and control means for an electrical motor driving said package or common spindle a second comparator which receives a feedback signal from the transducer connected to said package or common spindle so that said motor is controlled by a control signal which is a function of the output signal of the first comparator and the feed-back signal.

The apparatus will regulate the take-up speed with good precision even during transitional states (e.g. on start up). Precision in the number of twists per unit length of the yarn can be achieved as well as the omission of wheels and levers in the servo system between the bobbin drive shaft and take-up spindle.

The invention moreover offers a considerable advantage in permitting a centralised preselection of the number of twists per unit length required, said pre-selection being easily and rapidly programmable and modifiable.

Preferred embodiments of the invention will now be described with reference to the accompanying drawings, in which: Figure 1 illustrates schematically a first, open-loop embodiment of the invention, and Figure 2 illustrates schematically a second, closed-loop embodiment of the invention.

In the two drawings, similar parts or parts with similar functions are given similar references.

Thus 10 are the bobbins carrying the yarn to be twisted, said bobbins being rotated about their axes 11 in a known manner by motor means 12 through a common drive shaft 13, there being between the bobbins and the shaft 13 suitable velocity multiplying transmissions.

110 is an auxiliary or control bobbin without yarn and 111 is the axis of rotation thereof, 14 is a transducer for monitoring the speed of rotation of the drive shaft 13 of the bobbins which may be of the digital or the analogue type. Said transducer is connected in Figure 1 to the drive shaft 13 and in Figure 2 to the auxiliary or empty control bobbin 110 but it can also be connected to the individual bobbins 10. 15 is the output signal of the transducer 14, digital in the example though it may be analogue. 17 is the output signal of a selector 16, digital in the example. 18 is a signal processing group or first comparator which takes in signals 15 and 17 and produces an output signal 19, a frequency signal in the example, which controls a motor 21, said processing group 18 being of the digital type though it may also be of the analogue type.The motor 21 is controlled by an actuator 20 in turn controlled by the signal 19. The motor 20 controls the yarn winding velocity by driving a common spindle 22 which rotates the yarn packages 23. Said actuator 20 is, in the illustrated examples, a variable frequency feeder, and said motor 21 is a synchronous reluctance motor. The packages 23 are rotated by the spindle 22 against which said packages are tangentially pressed by known means not illustrated. 24 is a yarn winding velocity transducer suitable for closed loop feed-back regulation when connected as in Figure 2 to the winding spindle 22. 25 is a second comparator whereby signal 26 of transducer 24 is compared with signal 19 coming from the processing group or first comparator 18. The output signal 119 of the second comparator controls the actuator 20.

Referring firstly to the open loop embodiment of Figure 1, the rotational speed of the shaft 13, driving the bobbins 10 and driven by motor 12, is converted into a frequency signal by the transducer 14 and applied to the processing group or first comparator 18.

The processing group 18, according to the value of the twists per unit length of the yarn set in the selector 16, puts out the signal 19 which controls the rotational speed of the winding spindle 22 in relation to signal 17.

The signal 19 pilots the variable frequency feeder 20 of the synchronous motor 21 which regulates the rotational speed of the spindle 22 and hence the winding velocity of the yarn on the packages 23.

The packages 23 thus rotate at a speed which is a desired function of the rotational speed of the bobbins 10 and the required number of twists per unit length of the yarn passing between the bobbins 10 and the packages 23.

It is sufficient to set the selector at a new number of twists per unit length of the yarn if this latter quantity is changed and the process will continue.

If greater precision of operation is required the closed loop embodiment of Figure 2 may be used.

Here the speed of the rotation of the spindle 22 is compared with output signal 19 of the processing group 18 by means of transducer 24, whereby the difference between the two signals controls the frequency feeder 20.

It may be desired to obtain good performance even during transition conditions during which some slipping may occur between the bobbins 10 and the drive shaft 13 caused by inertia. In this case the auxiliary or control bobbin 110 is connected to the drive shaft 13.

In this way it is possible to record the true rotational speed of the bobbins 10 by connecting transducer 14 directly to the empty control bobbin 110.

It is possible to replace the synchronous motors by asynchronous ones or even by direct current motors.

It is also possible to supply visual counters of the number of twists per unit length of yarn as well as of the yarn take-up speed.

It is further possible to provide a centralised selection of the number of twists per unit length of the yarn.

It is feasible to utilise the invention in twosource twisters with one bobbin drive shaft and two independent take-up spindles.

It is possible to provide one transducer 14 for each bobbin 10, in which case working a preferential signal constituted either as a maximum value or a minimum value, or even by a mean value, is used as the output signal to the device 18.

WHAT WE CLAIM IS: 1. Apparatus for twisting yarn while it is passed between a bobbin and a take-up package,

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

Claims

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

speed with good precision even during transitional states (e.g. on start up). Precision in the number of twists per unit length of the yarn can be achieved as well as the omission of wheels and levers in the servo system between the bobbin drive shaft and take-up spindle.

The invention moreover offers a considerable advantage in permitting a centralised preselection of the number of twists per unit length required, said pre-selection being easily and rapidly programmable and modifiable.

Preferred embodiments of the invention will now be described with reference to the accompanying drawings, in which: Figure 1 illustrates schematically a first, open-loop embodiment of the invention, and Figure 2 illustrates schematically a second, closed-loop embodiment of the invention.

In the two drawings, similar parts or parts with similar functions are given similar references.

Thus 10 are the bobbins carrying the yarn to be twisted, said bobbins being rotated about their axes 11 in a known manner by motor means 12 through a common drive shaft 13, there being between the bobbins and the shaft 13 suitable velocity multiplying transmissions.

110 is an auxiliary or control bobbin without yarn and 111 is the axis of rotation thereof, 14 is a transducer for monitoring the speed of rotation of the drive shaft 13 of the bobbins which may be of the digital or the analogue type. Said transducer is connected in Figure 1 to the drive shaft 13 and in Figure 2 to the auxiliary or empty control bobbin 110 but it can also be connected to the individual bobbins 10. 15 is the output signal of the transducer 14, digital in the example though it may be analogue. 17 is the output signal of a selector 16, digital in the example. 18 is a signal processing group or first comparator which takes in signals 15 and 17 and produces an output signal 19, a frequency signal in the example, which controls a motor 21, said processing group 18 being of the digital type though it may also be of the analogue type.The motor 21 is controlled by an actuator 20 in turn controlled by the signal 19. The motor 20 controls the yarn winding velocity by driving a common spindle 22 which rotates the yarn packages 23. Said actuator 20 is, in the illustrated examples, a variable frequency feeder, and said motor 21 is a synchronous reluctance motor. The packages 23 are rotated by the spindle 22 against which said packages are tangentially pressed by known means not illustrated. 24 is a yarn winding velocity transducer suitable for closed loop feed-back regulation when connected as in Figure 2 to the winding spindle 22. 25 is a second comparator whereby signal 26 of transducer 24 is compared with signal 19 coming from the processing group or first comparator 18. The output signal 119 of the second comparator controls the actuator 20.

Referring firstly to the open loop embodiment of Figure 1, the rotational speed of the shaft 13, driving the bobbins 10 and driven by motor 12, is converted into a frequency signal by the transducer 14 and applied to the processing group or first comparator 18.

The processing group 18, according to the value of the twists per unit length of the yarn set in the selector 16, puts out the signal 19 which controls the rotational speed of the winding spindle 22 in relation to signal 17.

The signal 19 pilots the variable frequency feeder 20 of the synchronous motor 21 which regulates the rotational speed of the spindle 22 and hence the winding velocity of the yarn on the packages 23.

The packages 23 thus rotate at a speed which is a desired function of the rotational speed of the bobbins 10 and the required number of twists per unit length of the yarn passing between the bobbins 10 and the packages 23.

It is sufficient to set the selector at a new number of twists per unit length of the yarn if this latter quantity is changed and the process will continue.

If greater precision of operation is required the closed loop embodiment of Figure 2 may be used.

Here the speed of the rotation of the spindle 22 is compared with output signal 19 of the processing group 18 by means of transducer 24, whereby the difference between the two signals controls the frequency feeder 20.

It may be desired to obtain good performance even during transition conditions during which some slipping may occur between the bobbins 10 and the drive shaft 13 caused by inertia. In this case the auxiliary or control bobbin 110 is connected to the drive shaft 13.

In this way it is possible to record the true rotational speed of the bobbins 10 by connecting transducer 14 directly to the empty control bobbin 110.

It is possible to replace the synchronous motors by asynchronous ones or even by direct current motors.

It is also possible to supply visual counters of the number of twists per unit length of yarn as well as of the yarn take-up speed.

It is further possible to provide a centralised selection of the number of twists per unit length of the yarn.

It is feasible to utilise the invention in twosource twisters with one bobbin drive shaft and two independent take-up spindles.

It is possible to provide one transducer 14 for each bobbin 10, in which case working a preferential signal constituted either as a maximum value or a minimum value, or even by a mean value, is used as the output signal to the device 18.

WHAT WE CLAIM IS: 1. Apparatus for twisting yarn while it is passed between a bobbin and a take-up package,

wherein means is provided for automatically controlling the speed of rotation of the package as a function of a comparison between a first electrical signal proportional to the speed of rotation of the bobbin, or a control bobbin in tandem with said first-mentioned bobbin, and a second electrical signal proportional to a pre-selected number of twists per unit length imparted to the yarn as it passes between the bobbin and package.
2. Apparatus as claimed in claim 1, wherein the first electrical signal is obtained from a transducer monitoring the speed of rotation of the bobbin, or control bobbin, and the first and second signals are applied to a comparator the output signal of which is used to control a motor rotating the package.
3. Apparatus as claimed in either preceding claim, wherein a plurality of packages are jointly rotated by a common spindle to receive twisted yarn from a plurality of bobbins mounted to be jointly rotated by a common drive shaft, and wherein the speed of rotation of said common spindle is controlled as a function of a comparison between said first and second signals.
4. Apparatus as claimed in claim 3, wherein the first electrical signal is obtained from a transducer connected to the common drive shaft.
5. Apparatus as claimed in claim 3, wherein the first electrical signal is obtained from a transducer connected to an empty control bobbin mounted to be driven by said common drive shaft.
6. Apparatus as claimed in any preceding claim, wherein the speed of rotation of the take-up package, or common spindle, is monitored by a transducer.
7. Apparatus as claimed in claim 6, wherein there is interposed between the first-mentioned comparator and control means for an electrical motor driving said package or common spindle a second comparator which receives a feed-back signal from the transducer connected to said package or common spindle so that said motor is controlled by a control signal which is a function of the output signal of the first comparator and the feed-back signal.
8. Apparatus for twisting yarn while it is passed between a bobbin and a take-up package substantially as herein described with reference to and as illustrated in Figure 1 or Figure 2 of the accompanying drawings.