CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from Italian Patent Application No. 102017000088126 filed on 01/08/2017, the disclosure of which is incorporated by reference.

TECHNICAL FIELD

The present invention relates to a machine for wire bunching, also known with the name of "stranding machine", or "bunching machine" .

BACKGROUND ART

As is known, bunching (or stranding) consists in practice of spiral twisting of a wire bundle gathered and compacted to produce a cable or a rope with a typical spiral configuration.

The wires that form this bundle can come from different spools for storing the wire to produce a given bundle according to the number of wires and desired geometry.

For many years bunching devices have been known, wherein the wire bundle passes inside a guide, in which the bundle is pulled and inside which the bundle undergoes two twists that, depending on the twist speed and the feed speed thereof in the guide, determine the pitch of the spiral.

In particular, there are known bunching devices of the type with rotating bow comprising a pair of coaxial rotors, connected to the same motor drive in order to rotate jointly, on which there are defined, coaxially to the rotation axis and thus mutually aligned, respectively a first and a second passage, connected by a central passage formed by a bow fixed by the ends to the two rotors and thus rotating according to an axis coaxial to the first and second passage. Between the two rotors there is arranged a motorized winding spool, which is rotationally free from the rotors, being able to rotate independently due to its own motor drive. Upstream of the winding spool, there is provided a capstan device adapted to pull the wire before winding to determine the pitch.

Rotation of the aforesaid bow, on which the wires to be bunched run, allows two twists to be generated on the wire bundle substantially at the points in which this wire bundle exits from the first passage to enter the bow, and in which this bundle exits from the bow to enter the second passage.

A wire bunching machine having two bows (conventionally known in the present technical field such as "double twist machine") has been described in the patent application EP-B2-2369052 filed in the name of the same applicant .

The content of the description and of the drawings accompanying the patent application EP-B2-2369052 must be considered as integral parts of the present description, in particular with regard to the twisting system of the wire bundle.

As is known, currently three different types of stranding machines are known:

Type A) CAPSTAN PULL : This is the most widely used version of stranding machine as it allows a vast range of cables to be produced .

Its main limit consists in the fact that when the ratio between the products with the largest and smallest section is excessive, the products with the smallest section could undergo stretching due to the difficulty in managing the spooling traction (this can occur when wishing to produce cables with a small section on spools of dimensions larger than normal to obtain larger sizes of spool)

A further limit consists in the extreme difficulty in producing taped cables which, as is known, are cables covered externally by a tape applied tangentially in a spiral manner, practically a sort of wrapping. This operation makes the cable particularly delicate and therefore requires machine paths that are as linear as possible. The capstans introduce twists and turns in the path of the wire bundle to be twisted.

Type B) DIRECT PULL: This is the version used for products that do not require high stranding traction, such as cables that are insulated, taped, with a limited section or with particularly delicate sheaths; it has the undoubted advantage of costing less than Type A and of having a cradle path with few deviations.

Type C) BACK-TWIST : This is the typical version for manufacturing "counter-lay" cables, i.e., with the last layer forming the cord orientated in the opposite direction to the previous one. This solution overcomes the limit of the double twists of producing only "uni-lay" cords, i.e., with all the layers forming the cord orientated in the same direction as the helix .

One of the commercial problems frequently encountered in the field of stranding machines consists in the fact that the aforesaid three types A) , B) , C) are normally offered separately, each being specifically adapted to solve a given production problem.

Therefore, the need is felt to provide a stranding machine adapted to perform, according to choice and in a simple manner, the functions of all three types of machines A) , B) and C) . DISCLOSURE OF INVENTION

According to the present invention, a wire bunching machine is provided according to what is claimed in Claim 1, or to anyone of the claims directly or indirectly dependent on Claim 1.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention, a preferred embodiment will now be described purely by way of non-limiting example and with reference to the accompanying drawings, in which :

- Fig. 1 illustrates a wire bunching machine according to the invention in a first operating mode ("Capstan Pull" mode);

- Fig. 2 shows a wire bunching machine according to the invention in a second operating mode ("Direct Pull" mode);

- Fig. 3 illustrates a wire bunching machine according to the invention in a third operating mode ("Back-Twist" mode); and - Fig. 4 shows a side view (F) of the machine of Figs. 1-3.

BEST MODE FOR CARRYING OUT THE INVENTION

In the accompanying figures, the number 10 designates, as a whole, a wire bunching machine produced according to the teachings of the present invention.

The machine 10 comprises a support base 11 for a first, 12 and, respectively, a second rotor 13 driven by the same motor drive means 14.

The base 11 is C-shaped and thus comprises two end portions 11A, 11B joined by a cross member 11C.

In a known manner, the first 12 and second 13 rotors carry, interposed, a twisting bow 15 of the wire bundle; the wire bundle is schematised by the dot-and-dash line designated with the number 16 and slides along the twisting bow 15 in the same way described in the patent application EP-B2-2369052, to which reference is made.

A portal-shaped cradle 20, which will be described in more detail below, extends in a known manner under the twisting bow 15.

An inlet head 18 of the wire bundle 16 rests on the end portion 11B. The inlet head 18 is provided with a bearing adapted to support a first end 12A of the first rotor 12 and pulley means (not illustrated) adapted to give a first twist to the wire bundle 16.

A second end 12B of the first rotor 12 is supported by a bearing (not illustrated) mounted on the cradle 20.

With regard to the twisting mechanism of the wire bundle 16 by the pulley (not illustrated) and the twisting bow 15, the description relating to the patent application EP-B2-2369052 should be referred to.

An output head 19 of the wire bundle 16 rests on the end portion 11A. The output head 19 is also provided with a bearing adapted to support a first end 13A of the second rotor 13 and pulley means (not illustrated) adapted to give a second twist to the wire bundle 16.

A second end 13B of the second rotor 13 is supported by a bearing (not illustrated) mounted on the cradle 20.

In actual fact, the twisting bow 15 is supported by two return plates 25 and 26 (mutually opposite) integral with the rotors 12, 13, and which therefore rotate with these rotors 12, 13. In use, the two rotors 12, 13, the two return plates 25, 26 and the twisting bow 15 rotate, at relatively high speeds, around a longitudinal axis (XI) according to a direction and an orientation indicated by an arrow (Rl), describing complete revolutions through 360°.

Rotation of the aforesaid elements 12, 13, 15, 25, 26 is carried out by the aforesaid motor drive means 14, for example an electric motor connected to the rotor 13 by means of a belt 14A; said belt 14A extends between a first pulley 14B, fitted onto an output shaft of the motor drive means 14, and a second pulley 14C, fitted onto the rotor 13.

Therefore, the twisting bow 15 rotates rapidly, carrying out complete revolutions around the cradle 20 suspended between the heads 18, 19. It can be noted how the portal shape of the cradle 20 is such as to substantially follow the shape of the twisting bow 15.

As will be explained in more detail below, the cradle 20 undergoes brief oscillating movements around the axis (XI), but without ever carrying out a complete revolution around the axis (XI) .

The cradle 20 suspended between the two rotors 12, 13 comprises a main arch-shaped body 21 (in the shape of an upside-down U) .

The main body 21 internally houses, conventionally, a spool 22 provided with its own motor drive (not illustrated) independent from the motor drive means 14 of the two rotors 12, 13. As illustrated in the accompanying figures, the spool 22 is adapted to rotate around an axis (X2) (parallel to the aforesaid axis (XI)) according to two directions and two opposite orientations indicated by two arrows (R2) (Figs. 1, 2), (R3) (Fig. 3) .

Also housed inside the portal, that forms the main body 21, is a capstan device 23 also of conventional type and which, therefore, will not be described in detail. The capstan device 23 is joined to the portal 20.

Between the capstan device 23 and the spool 22 are two roller return means 27 and 28 fixed with conventional systems to the cradle 20.

In the first "Capstan Pull" mode shown in Fig. 1, the capstan device 23, by means of its own independent motor drive (not illustrated), is adapted to pull the wire bundle 16, before winding around the spool 22, to determine the winding pitch of the wire bundle 16. Between the second rotor 13 and the capstan device 23 is a deviator device 50, which is also part of the guide system of the wire bundle 16.

In the embodiment illustrated in the accompanying figures, the deviator device 50 comprises a first pulley 51 having a rotation axis (Yl) .

As illustrated in Fig. 4, the first pulley 51 lies on a plane (Π1), which forms an angle ( oil ) by intersecting a vertical plane (Π) where a front face 21A of said portal 21 lies.

The deviator device 50 also comprises a second pulley 52 having a rotation axis (Y2) . Again, as shown in Fig. 4, the second pulley 52 lies on a plane (Π2) which forms an angle (a2) by intersecting the aforesaid vertical plane (Π) .

In other words, the first pulley 51 and the second pulley 52 are crooked and are in series with each other.

Moreover, as illustrated in Figs. 2 and 3, the wire bundle 16, passing between the two pulleys 51 and 52, undergoes a change in the winding direction. In fact, when passing, at first, through the pulley 52 and then through the pulley 51 (Fig. 2), the wire bundle 16 passes from counter-clockwise winding at the pulley 52 to clockwise winding for the pulley 51.

The opposite occurs in the configuration illustrated in Fig. 3, for which the wire bundle 16 is wound in counter-clockwise direction in the pulley 51 and in clockwise direction in the pulley 52.

As we can see, by at least partially including/excluding and/or enabling/disabling the deviation means 50 in the guide system guiding the wire bundle 16 an operator can make the machine 10 operate in "Capstan Pull" mode, or in "Direct Pull" mode, or in "Back-Twist" mode (see below) .

In fact, if, as shown in Fig. 1, the operator causes the wire bundle 16 to be deviated from the second pulley 52 towards the capstan device 23 (Fig. 1) the machine 10 operates in "Capstan Pull" mode, in this case it is the capstan device 23 that pulls the wire bundle 16, which is then wound around the spool 22 after having passed through the two return means 27 and 28. In this case, the deviator device 50 is partially by-passed and the spool 22 simply winds the wire bundle 16 without any pulling action thereon.

Instead, in the "Direct Pull" mode illustrated in Fig. 2, the wire bundle 16 is wound, at first, through the second pulley 52, from which it is then deviated towards the first pulley 51, and from this, at first, towards the two roller return means 27, 28 and then towards the spool 22, which uses its independent motor drive to pull and wind the wire bundle 16.

In this case, it is the capstan device 23 that is completely by ^¬ passed.

The third and last mode, called "Back-Twist", can be used to produce "counter-lay" multi-layer cables, i.e., with the layers that form the cord orientated in alternating direction. In "Back-Twist" mode, the wire bundle 16, preliminarily wound on the spool 22 from which it is unwound, is caused to pass, at first, through the two roller return means 27, 28 and then through the first pulley 51, from which it is deviated towards the second pulley 52, and from the latter directly to the second rotor 13.

The wire bundle 16 goes back, in an opposite direction, along the twisting bow 15 and therefore the first rotor 12.

In other words, in this last case the wire bundle 16 goes back, in an opposite direction over the guide system seen in Fig. 2 for the "Direct Pull" mode. The wire bundle 16 exiting from the machine 10 is re-wound by an external motor-driven spool (not illustrated) .

As in "Back-Twist" mode the wire bundle 16 goes over the path in the opposite direction, it undergoes opposite torsions with respect to that of the "Direct Pull" mode.

As stated, "Back-Twist" mode is used to produce counter-lay multi-layer cables. Also in this last case, it is the capstan device 23 that is completely by-passed.

In all three "Capstan Pull", "Direct Pull", "Back-Twist" modes, the cradle 20 and/or the capstan device 23 can pitch around the longitudinal axis (XI) due to the reaction of the pull on the wire bundle 16.

The main advantages of the machine object of the invention are the following:

- with respect to a stranding machine on which only mode A) (the most widely used) can be implemented, the stranding machine object of the present invention can operate m the other two modes B) and C) with a minimum surcharge; and

- at the express request of the customer, the same stranding machine can be sold with the possibility of operating only in modes B) and C) without the capstan device decreasing the sales price of the machine.