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(11) | EP 2 166 135 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Machine for yarn twisting apt to be used as a twisting machine or as a cord machine |
| (57) The machine (1) comprises in succession an inlet station (3) provided with a yarn-braking
device (5), a first assembly (6 and 7) for twisting the yarn (2), a second assembly
(8) for drawing the yarn (2), a third assembly (9) for distributing the yarn (2),
a fourth assembly (10) for collecting the cross reel or the cop of the yarn (2), according
to the use, and means (11) for moving the rotary elements of said assemblies (6 and
7, 8, 9 and 10). The main characteristic of the present invention consists in the
fact that the yarn-braking device (5) comprises an electric motor (14) of which the
output shaft (15) controls the rotation about an axis (X) of a pulley (16) of the
kind having a plurality of annular races (17), wherein the yarn (2) is twisted; the
pulley (16) exerting a braking action against the advancement of said yarn (2).
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[0001] The present invention relates to a machine for yarn twisting, apt to be used as a twisting machine or as a cord machine.
[0002] Machines for twisting natural or synthetic fibre yarns comprise a yarn inlet station, a device for applying a predefined tension to the yarn, a pulley for drawing the yarn and a collecting assembly for collecting the cross reel or the cop of said yarn. As is known, to enable the correct and precise formation of the cross reel or cop of the yarn, immediately downstream of the inlet station there is a yarn-braking device consisting of an assembly that contrasts the drawing of the yarn towards the collecting assembly. The yarn-braking device consists of a pulley on which the yarn entering the machine is wound.
[0003] The main drawback of the machines currently available on the market consists in the fact that the yarn-braking device is hydraulically operated. Said yarn-braking device comprises an appropriately-sized reservoir, an indicator of the level of the liquid in the reservoir, a hydraulic pump, a filter, a pressure gauge, a pressure regulator and a series of ducts (pipes, fittings, etc.) provided with seals. In addition to the structural complexity, large overall dimensions and large number of components of said yarn-braking device, it is also difficult to adjust the hydraulic yarn-braking device to make said pulley apply the appropriate resistance to contrast the drawing of the yarn towards the collecting assembly. Moreover it is apparent that the braking action of the yarn-braking device results in an increase in the temperature of the pumped liquid so that, in order to avoid overheating, which can be dangerous and harmful, said liquid must be cooled for example by providing the yarn-braking device with a cooling device or by increasing the amount of liquid in the reservoir and thus providing the assembly with a larger reservoir. Moreover, the yarn-braking device must be checked periodically, which necessarily involves machine downtimes, to avoid the presence of air bubbles and of solid residues and to check the seal of all parts of the yarn-braking device.
[0004] The purpose of the present invention is to provide a machine for yarn twisting, apt to be used as a twisting machine or as a cord machine, that overcomes the drawbacks described above and that is thus provided with a yarn-braking device of simple construction, that has reduced overall dimensions, can be adjusted easily and quickly and does not require periodical tests and inspections.
[0005] According to the present invention there is provided a machine for yarn twisting, apt to be used as a twisting machine or as a cord machine, comprising in succession:
an inlet station provided with a yarn-braking device;
a first assembly for twisting said yarn;
a second assembly for drawing said yarn;
a third assembly for distributing said yarn;
a fourth assembly for collecting the cross reel or the cop of said yarn, according to the use; and
means for moving the rotary elements of said assemblies;
characterized in that said yarn-braking device comprises an electric motor of which the output shaft controls the rotation about an axis of a pulley of the kind having a plurality of annular races, wherein said yarn is twisted; said pulley exerting a braking action against the advancement of said yarn.[0006] In order to better understand the present invention a preferred embodiment thereof will now be described with reference to the accompanying drawings in which:
- figure 1 is a schematic view of a machine for yarn twisting, apt to be used as a twisting machine or as a cord machine, according to the present invention;
- figure 2 is a cross-section along the line II-II of figure 1; and
- figure 3 is a block diagram of an electronic control unit.
[0007] With reference to figure 1 designated as a whole by number 1 is a machine for yarn twisting 2, apt to be used as a twisting machine or as a cord machine, comprising in succession:
- an inlet station 3 provided with a plurality of pulleys 4 through which a yarn 2 passes and with a yarn-braking device 5;
- a first rotary element 6 of a known type to twist yarn 2 installed downstream of inlet station 3;
- a second rotary element 7 of a known type to twist yarn 2 installed downstream of first element 6;
- an assembly 8 (of a known type) for drawing yarn 2;
- an assembly 9 (of a known type) for distributing yarn 2;
- a collecting assembly 10 of a known type for collecting the cross reel or the cop of yarn 2, according to the use of the machine 1; and
- means 11 for moving the rotary elements of elements 6 and 7 and of assemblies 8, 9 and 10.
[0009] Said components of machine 1 are only described briefly in that they are of the type known in the prior art with the exception of yarn-braking device 5 as described below.
[0010] With reference to figure 2, the main characteristic of the present invention consists in the fact that yarn-braking device 5 comprises an electric motor 14 on the output shaft 15 of which is keyed a pulley 16 of the type provided with a plurality of annular races 17 wherein yarn 2 is twisted as it moves towards the element 6; the pulley 16 having an axis of rotation X.
[0011] Machine 1 as illustrated in figure 3 also comprises an electronic control unit 18 apt to control means 11 and electric motor 14. In particular control unit 18 comprises a memory block 21 for storing, for each diameter and material of yarn 2, the contrasting actions which said yarn-braking device 5 must exert against the advancement of said yarn 2 towards the collecting assembly 10. Control unit 18 also comprises a block 22 controlling means 11, a block 23 controlling electric motor 14, and a block 24 receiving signals from sensors 25 concerning values measured in machine 1. A first sensor 25 is apt to detect the drawing of yarn 2 for example between the elements 6 and 7 and thus of detecting whether the yarn 2 is under tension or slack due to being put under less tension than required for the assembly 10 to form a correct cross reel or cop of the yarn. A second sensor 25 is apt to detect a possible defibration of yarn 2, and namely to detect whether said yarn 2 is drawn in such a way that could jeopardise its integrity, thus leading to yarn 2 breaking. A third sensor 25 is installed in the inlet station 3 and is apt to detect the diameter of yarn 2. Connected to control unit 18 are a block 26 through which the user can plan the operation of the machine 1 and a display block 27 that displays the measurements in question and any alarm messages.
[0012] The contrasting action exerted by the yarn-braking device 5 can be exerted by applying a braking force against the advancement of yarn 2 from inlet station 3 to twisting element 6. Said braking force can be exerted by applying a braking torque to pulley 16 either by means of a command aimed at determining the rotation of pulley 16 (about the axis X) in the direction of advancement of yarn 2 but at a slower speed than that of the advancement of yarn 2 or by means of a command aimed at determining the rotation of pulley 16 (about the axis X) in the opposite direction to that of the advancement of yarn 2. In practice the value of the braking torque to be applied to pulley 16 is selected as a function of the material and of the diameter of yarn 2 which are defined by the user in block 26 in order to define the value of the contrasting action against the advancement of yarn 2; said braking torque value being stored in memory block 21. Control unit 18 can thus adjust the value of the braking torque on the basis of the data detected by sensors 25 and the control settings of means 11 and of motor 14, and in practice if control unit 18 counts the value of the braking torque as being outside a range set in memory block 21 for the specific operating conditions, it sends a command to change the value of said braking torque.
[0014] In particular the yarn-braking device that is provided is of reduced dimensions, can be assembled easily and quickly and consists of a small number of components with all the subsequent advantages in terms of costs of production, assembly and maintenance. Moreover the problems typically associated with a hydraulic motor such as the seal, difficulty with adjustment, cooling of the pumped liquid, etc. have all been overcome. It is apparent that an electric motor is far less complex to control than a hydraulic motor. The machine according to the present invention is provided with a control unit that automatically adjusts the control of the yarn-braking device, also according to the operating conditions detected by means of the sensors. Lastly, in certain conditions the electric motor of the yarn-braking device could be used as an electric generator so that the heat that was generated using a hydraulic motor is now converted into electric power that can be used in other stations of the plant of which the machine according to the present invention is part.
1. Machine for yarn twisting (2), apt to be used as a twisting machine or as a cord machine,
comprising in succession:
an inlet station (3) provided with a yarn-braking device (5);
a first assembly (6 and 7) for twisting said yarn;
a second assembly (8) for drawing said yarn (2);
a third assembly (9) for distributing said yarn (2);
a fourth assembly (10) for collecting the cross reel or the cop of said yarn (2), according to the use; and
means (11) for moving the rotary elements of said assemblies (6 and 7, 8, 9 and 10);
characterized in that said yarn-braking device (5) comprises an electric motor (14) of which the output shaft (15) controls the rotation about an axis (X) of a pulley (16) of the kind having a plurality of annular races (17), wherein said yarn (2) is twisted; said pulley (16) exerting a braking action against the advancement of said yarn (2).2. Machine according to Claim 1, characterized in that it comprises an electronic control unit (18) controlling said means (11) and said
electric motor (14) in order to contrast the advancement of said yarn (2).
3. Machine according to Claim 2, characterized in that said electronic control unit (18) comprises a first block (21) storing, for each
diameter and material of said yarn (2), the contrasting actions which said yarn-braking
device (5) must exert against the advancement of said yarn (2) towards said fourth
collecting assembly (10), a second block (22) controlling said means (11) and a third
block (23) controlling said electric motor (14).
4. Machine according to Claim 3, characterized in that said control unit (18) comprises a fourth block (24) receiving signals concerning
detected values from at least a sensor (25).
5. Machine according to Claim 4, characterized in that it comprises a first sensor (25) connected to said fourth block (24) and able to
detect the drawing of said yarn (2) downstream said inlet station (3), namely the
strain exerted on said yarn (2).
6. Machine according to Claim 4 and/or Claim 5, characterized in that it comprises a second sensor (25) connected to said fourth block (24) and able to
detect a possible defibration of said yarn (2), and namely if said yarn (2) undergoes
a drawing which could jeopardise its integrity, thus leading to its break.
7. Machine according to at leas a third sensor (25) connected to said fourth block (24)
and able to detect the diameter of said yarn (2).
8. Machine according to at least one of Claims 4-7, characterized in that it comprises a fifth block (26) through which the user can plan the operation of
said means (11), of said assemblies (6 and 7, 8, 9 and 10) and of said yarn-braking
device (5).