EP3336864B1

EP3336864B1 - A device for automatically adjusting wire tension during the various steps of winding in machines for winding electrical coils

Info

Publication number: EP3336864B1
Application number: EP17206731.6A
Authority: EP
Inventors: Gian Battista Parati
Original assignee: Marsilli and Co SpA
Current assignee: Marsilli and Co SpA
Priority date: 2016-12-16
Filing date: 2017-12-12
Publication date: 2020-08-26
Anticipated expiration: 2037-12-12
Also published as: IT201600127236A1; EP3336864A1

Description

The present invention relates to a device for automatically adjusting wire tension during the various steps of winding in machines for winding electrical coils.
As is known, the winding of coils for electrical or electromechanical components, although machines also exist that carry out the winding while keeping the reels still and moving the wire about them, is generally carried out by placing the reels on spindles which are actuated so as to rotate the reels about their axis and then feeding the wire to the reels so that it is progressively wound around them. Usually, in each coil, the wire is anchored, at the start and at the end of winding, to pins that are provided on the coil, by winding its ends around such pins.
In order to obtain a regular and uniform winding, as is required, it is necessary that the tension of the wire, during the winding, be kept as constant as possible.
To achieve this aim, special devices are used called "wire stretchers", which comprise, generally, a supporting structure that has loops and pulleys that define a path for the wire originating from a distaff/magazine and, along such path, there is usually a brake, a load cell for detecting the tension of the wire, and a takeup arm that can rotate, with respect to the supporting structure, about a corresponding axis and the function of which is to keep the wire under tension thus compensating the varying demand for wire from the elements that carry out its winding around the reel or the pins. The takeup arm is connected to springs, the function of which is to oppose the rotation of the takeup arm when the demand for wire increases, and to a damper, the function of which is to dampen the oscillations of the takeup arm about its own axis which are induced by the variations in tension of the wire.
In essence, in these conventional wire stretchers, the tension of the wire during its winding is detected by way of the load cells and the braking action performed by the brake is automatically varied, by way of a feedback control system, as a function of the value of the tension detected by the load cell compared to the desired tension value.
While maintaining a constant tension during the winding of the wire around the reel when the latter rotates at constant speed does not present particular problems, maintaining a constant tension in the presence of accelerations and decelerations of the rotation of the reel is difficult to achieve. The accelerations and decelerations of the rotation of the reel cause continual oscillations of the takeup arm about its own axis, which can cause damage to the damper. This problem is particularly felt in winding wires of relatively large diameter.
To solve this problem, in Italian Patent no. 1,420,251 or EP2866236 A1 a device has been proposed which comprises, along the path for the wire, an element for pushing and braking the wire and which is provided with means of detecting the rotation of the takeup arm about its own rotation axis with respect to the supporting structure. In such device, the means of detecting the rotation of the takeup arm are functionally connected to the pushing and braking element in order to achieve an automatic adjustment of the degree of thrust or braking applied on the wire as a function of the detected value of the rotation of the takeup arm about its rotation axis.
This device, although it makes it possible to obtain fully satisfactory results in most types of windings that can be carried out, has been found to be susceptible of improvements with regard to the winding of some types of coils in which the wire is arranged in multiple superimposed layers and, during the winding, it is necessary to operate with high accelerations and decelerations. In these operating conditions, the device described above exhibits difficulty in recovering wire sufficiently rapidly and therefore the problem arises of so-called "slow turns", i.e. turns of wire that are not sufficiently tensioned.
Another device for automatically adjusting wire tension is disclosed in DE19860608A1 .
The aim of the present invention is to solve the above mentioned drawback, by providing a device for automatically adjusting wire tension during the various steps of winding in machines for winding electrical coils which ensures a correct wire tension even in the presence of high accelerations and decelerations of the wire during winding, thus avoiding the formation of "slow turns".
Within this aim, an object of the invention is to provide a device that is capable of maintaining a constant tension of the wire during the winding even in windings with multiple layers of turns.
Another object of the invention is to provide a device that can be provided with components that are readily available, and that can be produced at low cost.
A further object of the invention is to provide a device that offers adequate assurances of safety and reliability of operation.
This aim and these and other objects which will become better apparent hereinafter are achieved by a device for automatically adjusting wire tension during the various steps of winding in machines for winding electrical coils, which comprises a supporting structure which supports a series of elements that define a path for the wire to be fed to the coil being wound, along said path being arranged:

an element for pushing and braking the wire;
a takeup arm which is supported so that it can rotate by said supporting structure about an axis and which can rotate about said axis, with respect to said supporting structure, owing to variations in the tension of the wire;
means of detecting the tension of the wire;
further means being provided of detecting the angular position of said takeup arm about said axis with respect to said supporting structure, said means of detecting the angular position of said takeup arm being functionally connected to said pushing and braking element for an automatic adjustment of the degree of thrust or braking applied to the wire as a function of the detected value of the rotation of said takeup arm about said axis;

Further characteristics and advantages of the invention will become better apparent from the description of a preferred, but not exclusive, embodiment of the device according to the invention, which is illustrated by way of non-limiting example in the accompanying drawings wherein:

Figure 1 is a perspective view of the device according to the invention;
Figure 2 is a front elevation view of the device according to the invention;
Figure 3 is a side elevation view of the device according to the invention with some elements omitted for greater clarity;
Figure 4 schematically illustrates the system of adjustment and control of the tension of the wire being wound of the device according to the invention.

With reference to the figures, the device according to the invention, generally designated by the reference numeral 1, comprises a supporting structure 2 which supports a series of elements that cooperate with each other to define a path for the wire 3 that has to be supplied to the reel around which it is to be wound.
Along this path there are, in particular: an element 4 for pushing and braking the wire 3, a takeup arm 5, which is supported so that it can rotate about an axis 6 by the supporting structure 2 and which can rotate about such axis 6, with respect to the supporting structure 2, by virtue of the variations in tension of the wire 3, and means of detecting the tension 7 of the wire 3.
The device in question also comprises means of detecting the angular position 8 of the takeup arm 5 about its rotation axis 6 with respect to the supporting structure 2. These means of detecting the angular position 8 of the takeup arm 5 are provided in addition to the means of detecting the tension 7 of the wire 3. The means of detecting the angular position 8 of the takeup arm 5 are functionally connected to the pushing and braking element 4 in order to obtain an automatic adjustment of the degree of thrust or braking, which is applied to the wire 3, as a function of the detected value of the rotation of the takeup arm 5 about the axis 6.
According to the invention, the device comprises an actuator 9 which is connected to the takeup arm 5 and which is adapted to vary the angular position of the takeup arm 5 about the axis 6; such actuator 9 is functionally connected to the means of detecting the tension 7 of the wire 3 in order to vary the angular position of the takeup arm 5 as a function of the tension of the wire 3.
More specifically, the supporting structure 2, in the embodiment shown, is constituted by a box-like body 10 which, on one of its faces, supports the series of elements that are engaged by the wire 3 to be fed to the reel.
Conveniently, the pushing and braking element 4 comprises a pulley 11 on which the wire 3 is wound and a motor 12, for example an electric motor of the brushless type, which actuates the pulley 11 with a torque that is variable and adjustable as a function of the rotation of the takeup arm 5 detected by the means of detecting the angular position 8 so as to maintain, substantially constantly, a preset tension of the wire 3.
The means of detecting the tension 7 of the wire 3 comprise a pair of pulleys 13, 14 with mutually parallel axes, which are engaged in sequence by the wire 3 that is fed to the reel and which are connected, in a way that is known per se, to a load cell 15 that constantly detects the tension applied to the wire 3.
Conveniently, the takeup arm 5 is pivoted, about the axis 6, to the supporting structure 2 by way of a region proximate to one of its ends. At the opposite end of the takeup arm 5 there is a pulley 16 around which the wire 3 to be fed to the reel engages.
The end of the takeup arm 5 that lies opposite the end that carries the pulley 16 is connected to elastic means 17 that contrast the rotation of the takeup arm 5 about the axis 6 in its direction of rotation that causes a reduction of the tension applied to the wire 3.
Such elastic means 17 comprise a helical spring 18 which is connected, by way of an end thereof, to the takeup arm 5 and, by way of the other end thereof, to the supporting structure 2.
The actuator 9 is preferably constituted by a piezoelectric linear actuator which is connected, by way of an end thereof, to the supporting structure 2, and, by way of the other end thereof, to a region of the takeup arm 5 arranged on the other side from the region with which the spring 18 engages with respect to the axis 6.
The actuator 9, according to how it is actuated, has the effect of boosting the action of the spring 18 or of reducing the action of the spring 18 on the takeup arm 5.
The means of detecting the angular position 8 of the takeup arm 5 comprise an angular transducer 19, for example a conventional encoder, which is connected to the takeup arm 5 by way of a belt connection 20.
Preferably, the pulley 11 of the pushing and braking element 4 is arranged upstream of the takeup arm 5 along the advancement direction of the wire 3 during the winding of the coil.
Preferably, the means of detecting the tension 7 of the wire 3 are arranged downstream of the takeup arm 5 along the advancement direction of the wire 3 during the winding of the coil.
More specifically, the wire 3 to be wound, originating from a distaff/magazine, upon entering the device, passes on a transmission pulley 21, then through a pair of cleaning felts 22, 23, then it winds around the pulley 11 of the pushing and braking element 4, then it engages with a transmission pulley 24, then it winds around the pulley 16 of the takeup arm 5 and, finally, it engages with the pair of pulleys 13, 14 and with an additional pulley 28 before being conveyed to the reel around which it is to be wound.
Conveniently, the means of detecting the tension 7 of the wire 3 are functionally connected to the actuator 9 by way of a first automatic feedback adjustment loop 25, conveniently of the electronic type, with a corresponding controller C1 which varies, by acting on the actuator 9, the force applied by this to the takeup arm 5 as a function of the tension applied to the wire 3 being wound.
Conveniently, the means of detecting the angular position 8 of the takeup arm 5 are functionally connected to the pushing and braking element 4 via a second automatic feedback adjustment loop 26, conveniently of the electronic type, with a corresponding controller C2 which varies the degree of thrust or braking applied to the wire 3 being wound by the pushing and braking element 4 as a consequence of the detection of a rotation of the takeup arm 5 about its own axis 6 with respect to the supporting structure 2.
Advantageously, there is a third automatic feedback adjustment loop 27 or adaptive loop, conveniently of the electronic type, with a corresponding controller C3 which manages the two automatic feedback adjustment loops 25 and 26. More specifically, the third automatic feedback adjustment loop 27 adjusts the sensitivity of the first automatic feedback adjustment loop 25 as a function of the rotation of the takeup arm 5 about its own axis 6, with respect to the supporting structure 2, detected by the means of detecting the angular position 8 of the takeup arm 5.
Operation of the device according to the invention is the following.
In order to prevent the "slow turn" phenomenon, it is necessary to be able to ensure, during winding, the following conditions:

constant tension of the wire 3 during all the winding steps;
limitation of the rotation of the takeup arm 5 about its own rotation axis 6 with respect to the supporting structure 2.

In the device according to the invention, these conditions are met in that, during the winding of the wire 3, as the working conditions vary, for example owing to variations of the rotation speed of the coil being wound, owing to variations of the winding diameter, which increases as the quantity of wire 3 wound increases, owing to variations of the friction that the wire 3 encounters along its path, caused by the pair of cleaning felts 22, 23 or by other resistances, the constancy of the tension of the wire 3 is ensured mainly by the intervention of the first automatic feedback adjustment loop 25 which, by detecting the tension of the wire 3 by way of the load cell 15, keeps the tension constant by intervening on the takeup arm 5 by way of the actuator 9 which causes a variation of the force exerted by the takeup arm 5 on the wire 3 being wound.
The limitation of the rotation of the takeup arm 5 about the axis 6 with respect to the supporting structure 2 is obtained mainly by way of the second automatic feedback adjustment loop 26 which, by measuring the angular position of the takeup arm 5 about the axis 6, makes it possible to have a programmable takeup of the wire 3 in the various steps of operation of winding the wire 3 onto the reel, such as for example the coupling of the wire 3 to anchor points on the reel, the actual winding itself, difficult passages of the wire 3, or variations in the position of the wire guide that directs the wire 3 onto the reel. The second automatic feedback adjustment loop 26 commands the actuation of the motor 12 as a function of the angular position of the takeup arm 5, making the motor 12 act as a motor or as a brake according to the working conditions and then returning the takeup arm 5 to the initial position i.e. to the preset position that it is desired be maintained.
The third automatic feedback adjustment loop 27 manages the first and the second automatic feedback adjustment loop 25 and 26, optimizing their behavior as a function of the working conditions and of the wire 3.
In essence, once the working position of the takeup arm 5 is fixed (generally at half of its angle of possible rotation about the axis 6) the second automatic feedback adjustment loop 26 ensures the takeup arm 5 is maintained around such position in all the steps of winding, while the first automatic feedback adjustment loop 25 keeps the tension of the wire 3 constant by actuating the actuator 9.
The third automatic feedback adjustment loop 27 intervenes on the angular position of the takeup arm 5 and on the reactivity of the first automatic feedback adjustment loop 25 on the basis of the working conditions.
In consideration of the fact that the objective to be achieved in order to guard against the phenomenon of "slow turns" is to keep the angular position of the takeup arm 5 as fixed as possible (usually at the center of the angle of possible rotation about the axis 6), any deviation of the takeup arm 5 from this preset or desired position results in a reaction of the first automatic feedback adjustment loop 25. As the deviation of the position of the takeup arm 5 increases with respect to the preset position, the third automatic feedback adjustment loop 27 increases the reactivity of the first automatic feedback adjustment loop 25 so that this intervenes, with the utmost rapidity, on the actuator 9 which corrects the position of the takeup arm 5, returning it to the preset position and thus keeping the tension of the wire 3 constant.
In practice it has been found that the device according to the invention fully achieves the set aim, in that it makes it possible to keep the wire tension substantially constant during the various steps of winding the coil, thus obtaining a regular winding of the wire, and in particular it makes it possible to avoid the occurrence of the phenomenon of "slow turns", even in the winding of some types of coils with layered turns, for which the occurrence of this problem would be more likely.
In practice the materials employed, and the dimensions, may be any according to requirements and to the state of the art.
Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly, such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.

Claims

A device (1)
for automatically adjusting wire tension during the various steps of winding in machines for winding electrical coils, which comprises a supporting structure (2) which supports a series of elements that define a path for the wire (3) to be fed to the coil being wound, along said path being arranged:
- an element (4) for pushing and braking the wire (3);

- a takeup arm (5) which is supported so that it can rotate by said supporting structure (2) about an axis (6) and which can rotate about said axis (6), with respect to said supporting structure (2), owing to variations in the tension of the wire (3);

- means of detecting the tension (7) of the wire (3);

- further means (8) being provided of detecting the angular position of said takeup arm (5) about said axis (6) with respect to said supporting structure (2), said means of detecting the angular position (8) of said takeup arm (5) being functionally connected to said pushing and braking element (4) for an automatic adjustment of the degree of thrust or braking applied to the wire (3) as a function of the detected value of the rotation of said takeup arm (5) about said axis (6);
characterized in that the device (1) comprises an actuator (9) which is connected to said takeup arm (5) and is adapted to vary the angular position of said takeup arm (5) about said axis (6), said actuator (9) being functionally connected to said means of detecting the tension (7) of the wire (3) in order to vary the angular position of said takeup arm (5) as a function of the tension of the wire (3) detected by said means of detecting the tension (7) of the wire (3).
The device according to claim 1, characterized in that said means of detecting the tension (7) of the wire (3) are functionally connected to said actuator (9) by way of a first automatic feedback adjustment loop (25) in order to vary the force applied by said actuator (9) to said takeup arm (5) as a function of the tension applied to the wire (3) being wound.
The device according to claim 2 , characterized in that said means of detecting the angular position (8) of said takeup arm (5) are functionally connected to said pushing and braking element (4) via a second automatic feedback adjustment loop (26) in order to vary the degree of thrust or braking applied to the wire (3) by said pushing and braking element (4) as a consequence of the detection of a rotation of said takeup arm (5) about its own axis (6) with respect to said supporting structure (2).
The device according to claim 3, characterized in that it comprises a third automatic feedback adjustment loop (27), which connects said means of detecting the angular position (8) of said takeup arm (5) to said first automatic feedback adjustment loop (25) in order to vary the sensitivity of said first automatic feedback adjustment loop (25) as a function of the rotation of said takeup arm (5) about said axis (6) with respect to said supporting structure (2).
The device according to one or more of the preceding claims, characterized in that said means of detecting the tension (7) of the wire (3) are arranged downstream of said takeup arm (5) along the advancement direction of the wire (3) during the winding of the coil.
The device according to one or more of the preceding claims, characterized in that said pushing and braking element (4) is arranged upstream of said takeup arm (5) along the advancement direction of the wire (3) during the winding of the coil.
The device according to one or more of the preceding claims, characterized in that said pushing and braking element (4) comprises a pulley (11) on which the wire (3) is wound and a motor (12) which actuates said pulley (11) with a torque that can vary as a function of the rotation of said takeup arm (5) about said axis (6) which is detected by said means of detecting the angular position (8) of said takeup arm (5).
The device according to one or more of the preceding claims, characterized in that said means of detecting the angular position (8) of said takeup arm (5) about said axis (9) comprise an angular transducer (19).
The device according to one or more of the preceding claims, characterized in that said actuator (9) is constituted by a piezoelectric linear actuator.
The device according to one or more of the preceding claims, characterized in that it comprises elastic means (17) which contrast the rotation of said takeup arm (5) about its own axis (6) with respect to said supporting structure (2) in the direction of rotation that reduces the tension of the wire (3).
The device according to claim 10, characterized in that said actuator (9) acts on said takeup arm (5) in agreement with or in contrast with the action of said elastic means (17).