"Improved annular locking device for the winding of reels" Description

The present invention relates to an annular device of the type used for locking and allowing the winding of reels of tape in multiple winding machines.

In the prior art relating to multiple winding machines so-called "friction shafts" are known, these comprising a plurality of annular devices arranged alongside each other for controlled locking of the cores of the reels mounted on the shaft.

In order to lock the cores of the reels the annular devices are provided with engaging elements which project radially in a controlled manner from the peripheral surface of the annular devices.

Usually, the annular devices each comprise two rings which are coaxial and radially superimposed, with the inner ring which is mounted on a rotational spindle and the outer ring which has projecting engaging elements (for example in the form of spheres or rolling cylinders).

The outer ring is rotatable through a certain angle on the inner ring, so as to move between a first angular rest position, in which the engaging elements are retracted or elastically retracted towards the inside of the outer ring, and a second angular locking position, in which the engaging elements are pushed outwards.

Usually elastic elements which push elastically the engaging elements outwards also when they are in the rest position are provided. This makes the rotational device less noisy and allows a controlled frictional movement of the cores on the shaft and precise axial centring of the cores. As the outer ring gradually rotates towards the locking position the elastic movement is gradually reduced until it is substantially eliminated when the ring reaches the locking position at the end of rotation.

Owing to the annular devices mounted on the shaft, in the angular rest position of the outer rings the cores of the reels may easily slide along the shaft so as to be able for example to be mounted or removed, while in the second position the cores of the reels are locked by the engaging elements so as to rotate together with the shaft.

A same shaft may be provided with as many as fifty or so annular devices, each with the outer ring rotatable independently of the other one and a more or less large number of reel cores may be mounted on the friction shaft thus composed.

When the devices have the outer ring in the rest position, the cores may be mounted on the shaft and slid along it until they reach they their correct position along the shaft.

Once all the cores have been loaded, a small rotation of the cores (performed manually or produced by the start of the winding rotation and therefore the start of pulling of the tape being wound) causes the rotation towards the locking position of the outer ring of all the devices which are situated inside the cores on which winding is to be performed.

The reel may in turn rotate with friction relative to the shaft. As a result it is possible to obtain variations in the pulling force of the single reels while using the same winding shaft.

Once winding of the reels has been completed, a suitable reverse rotation of the reels causes the rotation, back towards the rest position, of the outer ring of all the devices on which a reel is mounted, so as to allow the removal of the reels by axially sliding them along the shaft as far as their free end.

In view of the number of devices which are used on each shaft it is essential that they should be as simple as possible to manufacture and mount and that they should be robust and operationally reliable. Among other things, malfunctioning of one of them, in addition to preventing correct winding of the reels concerned, may prevent loading and unloading of the reels onto/from the shaft.

In the prior art it has been proposed to perform the movement of the engaging elements, upon rotation of the outer ring, by means of grooves with an increasing depth which are formed in the circumferential surface of the inner ring and inside which the engaging elements slide upon rotation of the outer ring. The elastic thrust of the engaging elements outwards is obtained by means of a short elastic plate section which is arranged inside each groove and fixed at one of its ends by means of a rivet or a through- screw, while the other end (at the end of the groove which corresponds to the rest position) is left free.

This structure, however, is fairly complicated both in terms of construction and as regards assembly of the device, especially if a satisfactory number of engaging elements to be provided along the circumference of the device.

Moreover, this solution, in addition to being complicated, limits the amount of sliding of the locking element inside the groove since an end section of the groove is occupied by the rivet. The elastic force generated moreover is not always satisfactory. The use of stronger plates would however complicate further the manufacture thereof and there are in any case dimensional constraints which must necessarily be complied with.

The general object of the present invention is to provide a locking device which is simple to construct and assemble and has several satisfactory characteristics during use.

In view of this object the idea which has occurred, according to the invention, is to provide an annular locking device for the winding of reels, comprising an inner ring and an outer ring coaxial with each other and radially superimposed so as to be rotatable relative to each other, between the inner ring and the outer ring there being arranged engaging elements which protrude radially from openings in the outer ring and which, upon rotation of the outer ring on the inner ring, each slide in a respective groove extending circumferentially in the inner ring, the outer ring being rotatable on the inner ring between a first angular rest position and a second annular locking position, in the first angular rest position the engaging elements being elastically retractable against the action of elastic means by a greater amount than in the second angular locking position, characterized in that each engaging element slides on an elastic plate which is located inside the respective groove and has opposite ends which are engaged inside undercut seats present in the corresponding opposite ends of the groove.

A rotational shaft with a plurality of these devices is also claimed.

In order to illustrate more clearly the innovative principles of the present invention and its advantages compared to the prior art, an example of embodiment applying these principles will be described below, with the aid of the attached drawings, in which:

- Figure 1 shows a partial schematic perspective view of a shaft provided with annular devices according to the invention;

- Figure 2 shows a cross-sectional view of an annular device provided according to the invention, along the line II- II of Figure 3;

- Figure 3 is a cross-sectional view of the device according to the invention along the line III- III of Figure 2;

- Figure 4 is a schematic side view of a part of the device.

With reference to the figures, Figure 1 shows in schematic form devices 10 according to the invention which are mounted side-by-side on a rotational shaft 11 of a known multiple winding machine (not shown). The devices will obviously be used in a variable number depending on whether longer or shorter shafts are to be provided or a greater or smaller number of adjacent reels are to be wound (one shaft, denoted by 30, is schematically shown in cross-section in Figure 1), as will be obvious to the person skilled in the art.

The device 10 comprises two superimposed coaxial rings 12 and 13. The innermost ring 12 is intended to be mounted on the rotational shaft, optionally with the arrangement, in between, of known friction elements (for example a layer of felt or the like) and, if required, with known controlled friction adjustment means (such as pneumatic chambers or the like) which may be easily imagined by the person skilled in the art and therefore are not further described or shown here. Engaging elements 14 project radially at intervals along the periphery through holes in the outermost ring 13. Advantageously, the dimensions of the holes are such as to prevent the engaging elements from coming out completely.

The rings and the engaging elements are advantageously made of metal.

The outer ring is rotatable axially relative to the inner ring so as to move between a first angular rest position, in which the engaging elements project elastically by means of suitable elastic means, and a second locking position, in which the elements may retract elastically less than in the rest position so as to lock the core of a reel 30 fitted on a rotational shaft provided with the device. This smaller degree of retraction may also be reduced to zero and the engaging elements pushed outwards in a substantially rigid manner.

The engaging elements 14 are formed preferably as rolling elements and, advantageously, in the form of spheres. Rolling cylinders may also be used if required.

Preferably, the engaging elements project in an equidistant manner along the circumference of the device. They may be for example six in number, spaced at 60° from one another. Obviously it is understood that the number of engaging elements may be different from that shown, depending on the specific requirements, as will also become clear below.

As will also become clear below and as can be seen for example in Figure 1 , advantageously the engaging elements protrude from the outer ring 13 alternately staggered along two different circumferential lines of the outer ring.

Figure 2 shows a cross-section of the device in a plane perpendicular to the axis of rotation of the rings and passing through the engaging elements 14. As can be seen in the figure the engaging elements 14 are housed so as to slide inside circumferential grooves 15 formed in the peripheral surface of the inner ring 12.

Advantageously, the rotation of the outer ring on the inner ring is limited by the extension of the grooves between an angular position in which the engaging elements 14 are at one end of the respective groove 15 and an angular position in which the engaging elements 14 are at the other end of the respective groove.

The bottom 16 of each groove is advantageously shaped to vary the depth of the groove from end to the other of the groove and forms a cam surface. In particular, each groove has a greater depth at the end corresponding to the angular position of the outer ring which is the rest position for the device 10 and has a smaller depth at the end corresponding to the angular position of the outer ring which is the locking position for the device 10.

An elastic plate segment 17 (for example made of spring steel) is present on the bottom of each groove 15. At the two ends the groove has corresponding undercut seats 18, 19 inside which the corresponding ends of the plate are inserted.

Preferably, the undercut seat 19, in the angular rest position, namely where the groove has a greater depth, has a height such as to allow the elastic movement of the plate towards the bottom of the groove.

Again preferably, the undercut seat 18, in the angular locking position, is advantageously heightwise (in the radial direction relative to the ring) smaller than the height of the undercut seat 19.

In this way, as can be clearly seen in Figure 2, when the outer ring is rotated between its two angular positions, each engaging element slides on the corresponding plate 17 between its rest position (shown in solid lines in Figure 2) where the plate has one end further removed from the bottom of the groove and the engaging element, if pushed from the outside, may retract elastically towards the inside of the ring, and its locking position (shown in broken lines in Figure 2) where the plate has a smaller elastic movement and preferably has its end substantially resting on the bottom of the groove and the engaging element is substantially in its locking position without any (or with a minimum) possibility of retracting elastically. The elastic plate is advantageously kept curved by the action of the two undercut seats at its ends and by the curvature of the bottom of the groove. There is thus an increased elastic effect compared to that which would be obtained with the same plate fixed at one end and completely free at the other end.

The grooves and the corresponding engaging elements may all lie in a same plane which intersects a circumference of the rings or be in staggered planes (for example two planes as in the embodiment shown).

This latter solution is for example useful in the case where the sum of the angles occupied by the grooves in the circumference of the inner ring is equal to or greater than 360° or in any case the distance between one groove and the next groove along the circumference is considered to be too small, if the grooves all lie in the same plane. This may be due to the number of grooves and/or the length of the said grooves.

The length of the grooves depends in general on the angle of rotation which is desired for the outer ring between its two angular end positions of the rotation.

In the example shown in the attached figures the grooves are advantageously six in number and arranged so as to obtain a desired rotation of the outer ring. Considering also the diameter of the engaging elements, which are formed as spheres, and the presence of the undercut seats for the ends of the elastic plates, the distance between the grooves would be nearly zero, if not zero, if the grooves were all in a single plane. It is therefore preferred to arrange advantageously three grooves in one plane and three grooves in a second plane with the group of three grooves in a plane which is rotated through 60° relative to the other group. This can be clearly seen from the comparison of Figures 2, 3 and 4.

As can be clearly seen in Figures 2 and 3 a device 20 for elastically coupling together the two rings in the rest position has also been provided. This coupling device preferably comprises a coupling element 21 (for example a small sphere) which is pushed by a spring 22 (for example a helical spring housed inside a suitable seat in the inner ring) so as to project radially from the inner ring and engage inside a matching seat 23 (for example a small hole) in the outer ring. A suitable rotational torque applied to the rings disengages the coupling element 21 from the seat and allows the normal relative rotation of the rings. With the return of the outer ring into the rest position the coupling element 21 returns elastically into its seat in the outer ring and the rings are again elastically engaged so as to prevent their free relative rotation.

The elastic thrust of the spring 22 will be chosen depending on the desired rotational torque necessary for moving the outer ring from the rest position on the inner ring. This torque will be preferably chosen so that it may be overcome at the start of the winding operations for a reel on the device 10, but such that at the same time it cannot be overcome by the normal forces which during use act on the devices 10 which do not support any reels and which therefore would otherwise be able to rotate freely.

In this way the rest position is prevented from becoming unstable and it is possible to limit or prevent altogether the problem that, during mounting or extraction of the cores onto/from the shaft provided with the annular devices, any annular devices not in the rest position along the shaft may prevent extraction or mounting of the cores.

Although the elastic coupling device 20 as illustrated has been found to be particularly advantageous, it may also be realized with a different elastic element, for example an elastic plate, and the coupling element may have a different form, as may be now easily imagined by the person skilled in the art. For example, in the case of a plate, the coupling element may also be a pin with a rounded head which is fixed onto the plate itself so as to project towards a matching engaging seat on the ring. Assembly of the device may also be reversed as regards the inner ring and outer ring, namely with the engaging seat in the inner ring and the elastic element and coupling element on the outer ring.

As can be clearly seen in Figures 3 and 4, for easy assembly of the device 10, each groove 15 has on one side a transverse passage 31 which connects the inside of the groove with the side wall of the inner ring. The dimensions and the position of the passage, which is advantageously formed as an open channel radially relative to the ring, are such as to allow the engaging element to pass towards the groove when the outer ring together with the engaging elements is slid axially on top of the inner ring.

This can be understood in particular from Figure 4, which shows a lateral view of only the inner ring from the side where the openings of the passages 31 in its side wall are present. In order to prevent the axial displacement of the outer ring on the inner ring during use of the device, allowing at the same time the desired angular rotation, the inner ring has advantageously on one side on a circumferential edge thereof a step 24, while a locking insert 25 with a wall transverse to the axis of the rings is coupled with the inner ring on the other side. As shown in Figure 3, the locking insert 25 may also be advantageously realized with a tubular portion 26 which is force-fitted inside the inner ring. Alternatively, a simple flat ring may also be fixed on one side of the inner ring.

The peripheral edge of the transverse wall of the locking insert and the opposite step 24 of the inner ring form a channel inside which the outer ring is rotatably seated.

For assembly of the device 10, after the plates have been inserted inside the respective grooves and they have been elastically inserted inside the end seats, it is sufficient to mount axially the outer ring with the engaging elements on the inner ring and then engage the locking insert 25 with the inner ring.

In the case where the elastic coupling device 20 is provided, it is inserted on the inner ring before mounting the outer ring.

At this point it is clear how the predefined objects have been achieved, providing an annular device of the type used for locking and allowing winding of reels of tape which has a simple and reliable structure and which allows a suitable elastic force to be applied on the engaging elements. The presence of the undercut seats at both the ends of the plate allows moreover precise adjustment of the elastic thrusting force of the plate along the entire movement path of the engaging elements. The plate may be elastically curved so as to provide a leaf spring effect. Moreover, the device may reduce or also eliminate the problem of the devices of the prior art which have an unstable rest position.

Obviously the above description applying the innovative principles of the present invention is provided by way of example of these innovative principles and must therefore not be regarded as limiting the scope of the rights claimed herein.

For example the dimensions and the proportions of the various parts of the device may vary depending on the specific practical requirements.