WINDER FOR WINDING A BAND OF FABRIC OR KNITTING OR THE LIKE ON A ROLLER, PARTICULARLY FOR CIRCULAR KNITTING MACHINES

Abstract

A winder for winding a band of fabric or knitting or the like on a roller, particularly for circular knitting machines, comprising a frame which supports a takeup roller and a traction roller, which is supported by the frame and can be actuated with a rotary motion about its own axis with respect to the frame, the traction roller making contact with the takeup roller, with the interposition of the band wound around the takeup roller, the traction roller being arranged so that its axis is above the axis of the takeup roller and can move toward or away from the axis of the takeup roller as the winding diameter of the band on the takeup roller varies, the winder comprising elements for the actuation of the traction roller with a rotary motion about its own axis with a substantially constant actuation torque.

Description

The present invention relates to a winder for winding a band of fabric or knitting or the like on a roller, particularly for circular knitting machines.

As is known, circular knitting machines are provided generally with a knitting tensioning device that is arranged below the needle cylinder of the machine and applies to the manufacture being formed a downward traction that is needed in order to ensure the correct forming of the manufacture.

These tensioning devices generally comprise a pair of rollers with mutually parallel and horizontal axes, between which the manufacture, constituted by a flattened tubular body, is caused to pass, and one of these two rollers is motorized so as to apply, in cooperation with the other roller, a traction to the manufacture.

Laterally to the motorized roller, on the side opposite to the roller that cooperates with it in applying traction to the knitted manufacture, generally there is another roller, which has the function of increasing the winding angle of the manufacture onto the motorized roller and of guiding the manufacture toward a takeup roller that is arranged below the tensioning device.

The takeup roller is part of a winding device that is arranged below the tensioning device and comprises generally a frame that supports, so that it can rotate about its own horizontally arranged axis, the takeup roller onto which the manufacture is to be wound.

In some winders the takeup roller is motorized, while in other winders the takeup roller is supported by the frame so that it can rotate about its own axis and is actuated by contact by means of at least one traction roller, which also is supported by the same frame so that it can rotate about its own axis, which is arranged parallel to the takeup roller axis. The traction roller can be actuated with a rotary motion about its own axis with respect to the frame and the takeup roller rests, with the interposition of the manufacture that winds about it, against the traction roller so that the rotary motion of the traction roller is transmitted by contact to the takeup roller, causing the progressive winding of the manufacture thereon.

For obtaining a uniform winding of the manufacture around the takeup roller without the manufacture undergoing unwanted deformations, the force with which the manufacture is tensioned during winding around the takeup roller must remain constant. To meet this requirement, two methods are usually used: a first method, which we will term “constant-speed operation”, and a second method, which we will term “constant-torque operation”.

In winders that use a traction roller, to which the present invention relates, constant-speed operation consists in setting a preset transmission ratio between the motorized roller of the tensioning device and the traction roller of the winder. By means of this method, each variation of the speed of the motorized roller of the tensioning device corresponds to an identical variation of the speed of the traction roller and therefore there are no changes in the tensioning force of the manufacture during its winding. The preset transmission ratio between the motorized roller of the tensioning device and the traction roller of the winder can be obtained by means of a mechanical transmission or by using variable-speed electric motors which can be controlled in a correlated manner.

In constant-torque operation, the takeup roller is actuated with a rotary motion about its own axis with a torque that can vary and with a rotation rate that can undergo variations as a function of the type of knitting that is manufactured and of the diameter of the roll of knitting being wound around the takeup roller so as to obtain in any case, at least in theory, a constant tensioning force of the manufacture during its winding.

Winding devices based on constant-torque operation are described for example in WO2011/042298 in the name of this same Applicant, which provides for limiting the actuation torque transmitted by the traction roller to the takeup roller, or in Italian patent 1,293,791 in the name of this same Applicant, which provides for actuating the takeup roller with a torque-controlled electric motor that is feedback-controlled by means of a transducer system capable of measuring the tension of the knitting at the input of the takeup roller.

Winders based on torque-controlled operation are preferred to winders based on speed-controlled operation in machines that perform knittings with variations of the type or quantity of knitting produced, such as for example in machines with electronic selection, with particular reference to those that transfer knitting from needles to continuous needles.

Among winders based on torque-controlled operation, winders that use a traction roller to actuate the takeup roller are the easiest to provide and manage.

In winders that use a traction roller to actuate the takeup roller and that are based on torque-controlled operation, the traction roller is arranged below the takeup roller, which rests thereon with the interposition of the manufacture, which winds progressively about the takeup roller. An arrangement of this kind is illustrated in the above-cited patent application WO2011/042298.

These winders have the drawback of being affected by the weight of the roll of the band of fabric that is wound progressively about the takeup roller. The total weight of the takeup roller and of the manufacture that winds about it increases progressively, varying the degree of adhesion of the takeup roller to the traction roller and the resistance opposed by the takeup roller to the rotary motion transmitted by the traction roller to the takeup roller. These variations can cause variations of the tensioning force of the manufacture during its winding around the takeup roller and therefore can alter the uniformity of the winding of the manufacture around the takeup roller.

The aim of the present invention is to obviate the drawback cited above, providing a winder for winding a band of fabric or knitting or the like around a roller, particularly for circular knitting machines, with a constant-torque operation that maintains a substantially constant tension of the band of fabric or knitting during its winding around the takeup roller so as to obtain a uniform winding, without deformations, of the strip of fabric or knitting or the like.

Within this aim, an object of the invention is to provide a winder in which the winding tension of the band of fabric or knitting or the like is not affected by the amount of knitting or fabric that is wound around the takeup roller.

Another object of the invention is to provide a winder in which it is possible to vary the tension to which the band of fabric or knitting or the like is subjected during winding around the takeup roller.

An additional object of the invention is to provide a winder that ensures high precision and reliability in operation.

Another object of the invention is to propose a device that can be manufactured at competitive costs and is easy to manage.

This aim, as well as these and other objects that will become more apparent hereinafter, are achieved by a winder for winding a band of fabric or knitting or the like around a roller, particularly for circular knitting machines, comprising a frame which supports, so that it can rotate about its own horizontally arranged axis, a takeup roller, around which the band of fabric or knitting or the like is to be wound, and at least one traction roller, which is supported so that it can rotate about its own axis, which is arranged parallel to the axis of said takeup roller, by said frame and can be actuated with a rotary motion about its own axis with respect to said frame; said traction roller making contact with said takeup roller, with the interposition of said band wound around said takeup roller, for a transmission of the rotation of said traction roller to said takeup roller, characterized in that said traction roller is arranged so that its axis is above the axis of said takeup roller and can move toward or away from the axis of said takeup roller as the winding diameter of said band on said takeup roller varies, means being provided for the actuation of said traction roller with a rotary motion about its own axis with a substantially constant actuation torque.

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

FIG. 1 is a partially exploded perspective view of the winder according to the invention;

FIG. 2 is a perspective view of the winder according to the invention, with the strip of fabric or knitting or the like to be wound omitted;

FIG. 3 is a perspective view of the winder according to the invention, from a different angle than in FIG. 2;

FIG. 4 is a schematic view of the winder according to the invention, illustrating its operation.

With reference to the cited figures, the winder according to the invention, generally designated by the reference numeral 1, comprises a frame 2 that supports, so that it can rotate about its own axis 3a, which is arranged horizontally, a takeup roller 3 about which the band 4 of fabric or knitting or the like is intended to be wound. The winder 1 comprises a traction roller 5 that is supported, so that it can rotate about its own axis 5a, which is arranged parallel to the axis 3a of the takeup roller 3, by the frame 2 and can be actuated with a rotary motion about its own axis 5a with respect to said frame 2. The traction roller 5 makes contact with the takeup roller 3, with the interposition of the band 4 wound about the takeup roller 3, in order to transmit the rotation of the traction roller 5 to the takeup roller 3.

According to the invention, the traction roller 5 is arranged so that its axis 5a lies above the axis 3a of the takeup roller 3 and can move toward or away from the axis 3a of the takeup roller 3 as the winding diameter of the band 4 on the takeup roller 3 varies. The winder 1 according to the invention comprises means 6 for actuating the traction roller 5 with a rotary motion about its own axis 5a with a substantially constant actuation torque.

More particularly, the frame 2 is composed of a lower profiled element 7, which is arranged substantially horizontally and from which two vertical shoulders 8a, 8b rise which are mutually connected, at their upper end, by a horizontal bar 9. If the winder according to the invention is intended to be fitted on a circular knitting machine, the shoulders 8a, 8b can be provided in an upward region with arms 10a, 10b so as to connect the frame 2 below the needle cylinder of the machine.

In the illustrated embodiment, the frame 2 supports, in proximity to the upper end of the shoulders 8a, 8b, a tensioning device 11 of a known type, for example a tensioning device of the type described in WO2011/042298, which is composed of three side-by-side rollers 12, 13, 14, respectively: a motorized central roller 12, a contact roller 13 that is arranged on one side of the central roller 12, and a guiding roller 14 that is arranged on the other side of the central roller 12. The rollers 12, 13, 14 are arranged so that their axes are horizontal and mutually parallel and the band 4 to be wound about the takeup roller 3 passes between the contact roller 13 and the central roller 12 to then pass between the central roller 12 and the guiding roller 14 to reach finally the takeup roller 3, which is supported by the frame 2 so that its axis 3a is arranged in parallel to the axes of the rollers of the tensioning device.

The takeup roller 3 is composed of a cylindrical jacket about which the band 4 is to be wound and which is closed, at its axial ends, by portions of a shaft or coaxial pivots that constitute the axial ends of the takeup roller 3. These axial ends of the takeup roller 3 are coupled, in a rotatable manner, with the interposition of bearings 15, to the shoulders 8a, 8b of the frame 2.

The means 6 for actuating the traction roller 5 comprise a rack 16a, 16b, which is supported, so that it can slide, by the frame 2 along a direction that is perpendicular to the axis 5a of the traction roller 5. The rack 16a, 16b meshes with a pinion 17a, 17b, which is connected to the traction roller 5 by means of a unidirectional motion transmission device 18, which is adapted to render the pinion 17a, 17b integral with the traction roller 5 in rotation about its own axis 5a in a forward rotation direction, which causes a rotation of the takeup roller 3 in the direction for winding the band 4 about the takeup roller 3, and to uncouple the pinion 17a, 17b from the traction roller 5 in a return rotation direction that is opposite to the forward rotation direction. The rack 16a, 16b is actuated with a translational motion along its axis, at least in the direction of translation that produces the forward rotation direction of the pinion 17a, 17b, with a substantially constant force.

More particularly, the actuation means 6 of the traction roller 5 comprise a rack 16a, 16b that meshes with a pinion 17a, 17b connected to the traction roller 5 by means of a corresponding unidirectional motion transmission device 18 for each one of the axial ends of the traction roller 5.

Conveniently, each one of the pinions 17a, 17b that meshes with the corresponding rack 16a, 16b is fitted coaxially on one of the axial ends of the traction roller 5 and the corresponding unidirectional motion transmission device 18 is constituted preferably by a freewheel device that is interposed between the respective pinion 17a, 17b and the corresponding axial end of the traction roller 5.

Preferably, the arrangement of the takeup roller 3 and of the traction roller 5 on the frame 2 is such that the axis 3a of the takeup roller 3 and the axis 5a of the traction roller 5 are arranged on a same vertical plane so that the axis 5a of the traction roller 5 is arranged above the axis 3a of the takeup roller 3.

With this arrangement, which is the one shown, the racks 16a, 16b are arranged so that their axis is vertical and are conveniently guided by the shoulders 8a, 8be along a corresponding vertical direction.

The axial ends of the traction roller 5 are accommodated slidingly within vertical guides 21a, 21b that are integral with the frame 2.

More particularly, bearings 22a, 22b are fitted on the axial ends of the traction roller 5, externally with respect to the region occupied by the pinions 17a, 17b, each bearing engaging slidingly within a corresponding vertical guide 21a, 21b that is formed in the corresponding shoulder 8a, 8b of the frame 2. In this manner, the traction roller 5 can slide vertically upward as the amount of band 4 wound onto the takeup roller 3 increases.

Each one of the racks 16a, 16b is actuated with a translational motion along its own axis, in the direction of translation that causes the forward rotation direction of the corresponding pinion 17a, 17b, by means of a spring 23a, 23b that is reloaded cyclically by a fluid-operated cylinder 24a, 24b.

More particularly, for each one of the racks 16a, 16b there is a pivot 25 that is integral with the rack 16a, 16b and is connected to another pivot 26 fixed to a plate 27 that is integral with the corresponding shoulder 8a, 8b of the frame 2 by means of the spring 23a, 23b. It should be noted that along the longitudinal extension of each rack 16a, 16b there are multiple holes 28 for positioning the pivot 25 so as to make it possible to vary the preloading of the spring 23a, 23b according to the requirements. The spring 23a, 23b is arranged so as to contrast the movement of the rack 16a, 16b upward, i.e., cause the movement of the rack 16a, 16b downward with respect to the frame 2. The fluid-operated cylinder 24a, 24b is connected with its body to the corresponding shoulder 8a, 8b of the frame 2 and operates with the stem of its piston on an end of the corresponding rack 16a, 16b. Essentially, the actuation of the fluid-operated cylinder 24a, 24b causes the upward movement of the rack 16a, 16b and the loading of the spring 23a, 23b, whereas the discharge, i.e., the deactivation, of the fluid-operated cylinder 24a, 24b causes the downward movement of the rack 16a, 16b by the action of the spring 23a, 23b. The downward movement of the rack 16a, 16b, as a consequence of the coupling that exists between the rack 16a, 16b and the corresponding pinion 17a, 17b, turns the pinion 17a, 17b in the forward rotation direction, which causes the rotation of the traction roller 5 and consequently, by contact, the rotation of the takeup roller 3 in the winding direction 20, whereas the upward movement of the rack 16a, 16b causes no rotation of the traction roller 5, since the pinion 17a, 17b rotates in the return rotation direction, which, as a consequence of the presence of the freewheel device 18, transmits no rotation to the traction roller 5 and therefore to the takeup roller 3.

Essentially, the force that generates the actuation torque that is transmitted by the traction roller 5 to the takeup roller 3 is the force produced by the elastic reaction of the spring 23a, 23b that is loaded cyclically by the fluid-operated cylinder 24a, 24b. By limiting appropriately the stroke of the fluid-operated cylinder 24a, 24b and consequently the elongation of the spring 23a, 23b during loading, the force generated by the spring 23a, 23b and transmitted, by means of the coupling that exists between the rack 16a, 16b and the pinion 17a, 17b and by means of the unidirectional motion transmission device 18, to the traction roller 5 is substantially constant and therefore generates a substantially constant actuation torque of the traction roller 5.

Consequently, the force that is transmitted by the traction roller 5 to the takeup roller 3 is also substantially constant, thus achieving a substantially constant tensioning of the band 4 during its winding around the takeup roller 3. In practice, the tension T to which the band 4 is subjected during its winding about the takeup roller 3 is expressed by the formula (see FIG. 4):

T=F_t=C_t/R_t=F_m·R_p/R_t

As explained above, by a reduction in the extent of the movement of the rack 16a, 16b by means of the action of the fluid-operated cylinder 24a, 24b, the tension T remains substantially constant.

By means of the movement of the fixing point of the pivot 25 along the rack 16a, 16b it is possible to vary the preloading of the spring 23a, 23b and consequently to vary the tension that bears on the band 4 during winding around the takeup roller 3.

As an alternative, instead of a helical spring 23a, 23b, as shown, it is possible to use a pneumatic spring that can be included in the fluid-operated cylinder that can be actuated cyclically in order to reload the pneumatic spring. In this case it is possible to vary the winding tension of the band 4 by adjusting the force generated by the pneumatic spring.

As a further alternative, each rack 16a, 16b can be actuated with an alternating translational motion along its own axis by means of a double-acting fluid-operated cylinder. In this case it is possible to vary the winding tension of the band 4 by varying the supply pressure of the double-acting fluid-operated cylinder.

For the sake of completeness in description, it should be noted that the frame 2 can also be supported by means of a lower supporting element 29 that supports the frame 2 so that it can rotate about a vertical central axis which, in the installation of the device on the knitting machine, is arranged at the axis of the needle cylinder in order to allow the frame 2 to rotate together with the needle cylinder of the knitting machine.

Operation of the device according to the invention is as follows.

At the beginning of the winding of the band 4 around the takeup roller 3, the traction roller 5 is proximate to the lower end of the vertical guides 21a, 21b, as shown in FIGS. 2 and 3. The band 4 of fabric or knitting or the like, which arrives from the tensioning device 11, is wound with an initial portion around the takeup roller 3 and the actuation of the traction roller 5 with a rotary motion about its own axis 5a produces by contact the rotation of the takeup roller 3 about its own axis 3a and therefore the progressive winding of the band 4 that originates from the tensioning device 11 about it. As explained above, the traction roller 5 is actuated by means of the alternating movement of the racks 16a, 16b along their own axis, i.e., in the illustrated embodiment, along a vertical direction. This alternating translational motion, during the rising motion, has no effect on the rotation of the traction roller 5, whereas during the descending motion it causes the rotation of the traction roller 5 integrally with the pinions 17a, 17b that mesh with the corresponding rack 16a, 16b and consequently causes by contact the rotation of the takeup roller 3 in the winding direction 20. Due to the fact that the force that causes the downward movement of the rack 16a, 16b is substantially constant, the force transmitted by the traction roller 5 to the takeup roller 3 is substantially constant and consequently the tensioning of the band 4 during its winding about the takeup roller 3 is substantially constant. As a consequence of the progressive winding of the band 4 about the takeup roller 3, the diameter of the assembly constituted by the takeup roller 3 and by the band 4 wound around it increases progressively, with consequent rise of the traction roller 5 with its axial ends along the vertical guides 21a, 21b.

It should be noted that in the device according to the invention the takeup roller 3 does not rest on the traction roller 5 and therefore its progressive increase in diameter and weight as the winding of the band 4 progresses does not cause substantial variations of the force that is transmitted by the traction roller 5 to the takeup roller 3 and consequently of the tensioning of the band 4, which therefore remains substantially constant during winding.

To avoid a rotation of the takeup roller 3 in the direction opposite to the winding direction 20 in the step for loading the spring 23a, 23b, it is possible to interpose unidirectional rotation devices, such as for example freewheel devices, also between the axial ends of the takeup roller 3 and the shoulders 8a, 8b that support them.

In practice it has been found that the device according to the invention achieves fully the intended aim, since it ensures a substantially constant tensioning of the band of fabric or knitting or the like during its winding about the takeup roller, allowing uniform winding even with reduced tensions.

A further advantage of the device according to the invention is that it can be actuated in a very simple manner and allows precise adjustment of the tension to which the band of fabric or knitting or the like is subjected during winding.

The device thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the inventive concept; thus, for example, instead of providing two racks 16a, 16b it is possible to provide a single rack.

All the details may further be replaced with other technically equivalent elements.

In practice, the materials used, as well as the dimensions, may be any according to the requirements and the state of the art.

The disclosures in Italian Patent Application No. MI2012A001090 from which this application claims priority are incorporated herein by reference.

Claims

1-11. (canceled)

12. A winder for winding a band of fabric or knitting or the like on a roller, particularly for circular knitting machines, comprising a frame which supports, so that it can rotate about its own horizontally arranged axis, a takeup roller, on which the band of fabric or knitting or the like is to be wound, and at least one traction roller, which is supported, so that it can rotate about its own axis, which is arranged in parallel to the axis of said takeup roller, by said frame and can be actuated with a rotary motion about its own axis with respect to said frame; said traction roller making contact with said takeup roller, with the interposition of said band wound around said takeup roller, for a transmission of the rotation of said traction roller to said takeup roller, wherein said traction roller is arranged so that its axis is above the axis of said takeup roller and can move toward or away from the axis of said takeup roller as the winding diameter of said band on said takeup roller varies, means being provided for the actuation of said traction roller with a rotary motion about its own axis with a substantially constant actuation torque.

13. The device according to claim 12, wherein said actuation means comprise a rack, which is supported, so that it can slide, by said frame along a direction which is perpendicular to the axis of said traction roller, said rack meshing with a pinion connected to said traction roller by means of a unidirectional motion transmission device adapted to render said pinion integral with said traction roller in rotation about its own axis in a forward rotation direction which actuates a rotation of said takeup roller in the direction of the winding of said band on said takeup roller and to uncouple said pinion from said traction roller in a return direction of rotation which is opposite to said forward rotation direction, said rack being actuated with a translational motion along its own axis, at least in the direction of translation that causes said forward rotation direction of said pinion, with a substantially constant force.

14. The device according to claim 12, wherein said actuation means comprise a rack which meshes with a pinion, which is connected to said traction roller by means of a corresponding unidirectional motion transmission device for each one of the axial ends of said traction roller.

15. The device according to claim 14, wherein said unidirectional motion transmission device is a device of the freewheel type.

16. The device according to claim 14, wherein said pinion is fitted coaxially on an axial end of said traction roller, said unidirectional motion transmission device being interposed between said traction roller and said pinion.

17. The device according to claim 12, wherein the axis of said traction roller and the axis of said takeup roller lie on a same vertical plane.

18. The device according to claim 12, wherein axial ends of said traction roller are accommodated slidingly within vertical guides which are integral with said frame.

19. The device according to claim 14, wherein said rack is actuated with a translational motion along its own axis, in the direction of translation that causes said forward rotation direction of said pinion, by means of a spring which is reloaded cyclically by a fluid-operated cylinder.

20. The device according to claim 14, wherein said rack is actuated with a translational motion along its own axis, in the direction of translation that causes said forward rotation direction of said pinion, by means of a pneumatic spring which is embedded in a fluid-operated cylinder which can be actuated cyclically in order to reload said pneumatic spring.

21. The device according to claim 14, wherein said rack is actuated with an alternating translational motion along its own axis by means of a double-acting fluid-operated cylinder.

22. The device according to claim 19, further comprising means for adjusting an actuation force of said rack at least in the direction of translation that causes said forward rotation direction of said pinion.