WO2026018151A1 - An extractor for removing winding mandrels from logs of web - Google Patents

Abstract

The extractor comprises an expandable pin that is configured to be inserted into the winding mandrel and to engage the winding mandrel by expansion.

Description

AN EXTRACTOR FOR REMOVING WINDING MANDRELS FROM LOGS OF WEB MATERIAL

DESCRIPTION

TECHNICAL FIELD

[0001] The present invention relates to devices and methods for removing a winding mandrel from a log of web material wound around the mandrel. The invention also relates to components of the device and methods for removing winding mandrels from logs of web material.

BACKGROUND ART

[0002] In many industrial sectors, it is customary to wind a web material around a winding mandrel or winding core. Typically, in the paper converting industry, particularly tissue paper converting, it is known to wind a paper web, consisting of one or more plies, around a winding core or winding mandrel to form a log. The logs are usually produced in rapid sequence in a rewinder, such as a continuous, automatic peripheral rewinder. Examples of rewinders of this type are disclosed in EP2621844, EP 1725485, EP0694020.

[0003] Typically, the logs have an axial length significantly greater than the finished products, which consist of rolls of shorter axial length, obtained by transversally cutting the logs produced by the rewinder.

[0004] In some cases, the web material is wound around logs of paper, cardboard, or plastic, which remain inside the logs and are cut together with the logs.

[0005] In the past, systems have been studied to remove the winding core or winding mandrel from the finished log, in order to reuse the mandrels multiple times in subsequent cycles for winding more logs. In this way, there is no longer the need to produce large quantities of winding cores or mandrels, which are a cost for the log manufacturer and a source of pollution. In fact, when the winding core is cut together with the log and remains inside the rolls destined for the end consumer, the end consumer throws it away once the roll, for example a roll of toilet paper or kitchen towels, is exhausted.

[0006] EP1056667 discloses a peripheral rewinder that winds logs of web material, typically tissue paper, around removable mandrels. The mandrels are made in two halves, i.e., two half-mandrels that are matched together along the winding axis. An extracting device is provided downstream of the rewinder, that removes the two half-mandrels from the two ends of the logs exiting the rewinder; the half-mandrels are then sent back to the rewinder inlet and coupled together before being inserted into the rewinder to perform a new winding cycle.

[0007] EP2678257 discloses a production line for paper logs, particularly tissue paper logs, which comprises a rewinder and a log accumulator. The logs are ejected from the rewinder and loaded onto the log accumulator, downstream of which other converting machines are provided, particularly a severing machine that cuts the logs into smaller rolls intended for the end consumer. An extractor is provided between the rewinder and the log accumulator, that removes the half-mandrels from the two ends of the logs that are unloaded from the rewinder.

[0008] WO2020/245319 discloses a device for removing mandrels from tissue paper logs through a combined motion of axial translation and rotation of the mandrel around its own axis, to facilitate the mandrel extraction by reducing the friction between the mandrel and the log.

[0009] US20240025686 discloses a further extractor for removing winding mandrels from tissue paper logs, which uses an expandable member to grip the mandrel. The expandable gripping member is either pneumatic or mechanical.

[0010] DEI 9957990 discloses an expandable gripping member for removing winding mandrels from paper logs.

[0011] One of the complex aspects in the log extractor design is the need for the extractor to firmly engage the mandrel, or the half-mandrel, in order to remove it against the friction force, without damaging the mandrel and without the mandrel accidentally detaching from the extractor. Moreover, it would be useful to provide an extractor that does not require the use of complexly shaped mandrels, for example mandrels comprising gripping flanges, because these mandrels are expensive.

[0012] The object of embodiments described herein is to provide a low-cost, reliable extractor that can be used with mandrels of simple tubular shape.

SUMMARY OF THE INVENTION

[0013] According to an aspect, an extractor for removing winding mandrels, or half- mandrels, from logs of wound web material is disclosed, wherein the extractor comprises an expandable pin configured to be inserted into the winding mandrel and to engage the winding mandrel by expansion.

[0014] In some embodiments, the expandable pin comprises a rod and at least one annular body surrounding the rod, the annular body being radially expandable around the rod, so as to engage, by pressure, an inner surface of the winding mandrel.

[0015] In advantageous embodiments, the pin comprises a plurality of annular bodies arranged in sequence along the axial extension of the rod. Each annular body is radially expandable around the rod to engage, by pressure, the inner surface of the winding mandrel.

[0016] In advantageous embodiments, the annular bodies are arranged on the rod, free to slide relative thereto.

[0017] In some embodiments, rigid annular elements are provided between adjacent annular bodies. More specifically, a rigid annular element is provided interposed between each pair of adjacent annular bodies, i.e., consecutive along the axial extension of the rod. The rigid annular element(s) is(are) advantageously mounted slidingly on the rod, i.e., in such a manner that they can slide along the longitudinal extension of the rod.

[0018] In advantageous embodiments, each annular body is elastically deformable in axial and radial directions, and is configured so that a reduction in the length in axial direction causes an expansion of the annular body in radial direction.

[0019] In practice, each elastically deformable annular body has a minimum energy configuration corresponding to a maximum axial dimension and a minimum radial dimension.

[0020] In embodiments described herein, the rod is housed in a sliding seat so as to slide axially in the sliding seat under the control of an expansion actuator, in order to move between a removal position and a retracted position relative to the axial seat.

[0021] The rod comprises, for example, a radial end stop, such that the retraction of the rod relative to the sliding seat causes the rod to slide within each annular body and each annular body to contract axially and to expand radially.

[0022] An extractor device is described below for removing mandrels, divided into two half- mandrels, from logs of web material, typically tissue paper, with a particularly advantageous structure in terms of efficiency and productivity. However, it should be understood that the configuration of the extractor defined above, and better described in detail with reference to an embodiment illustrated in the drawing, can also be used in extractor devices for removing mandrels or half-mandrels different than those described herein, for example not integrated with a log accumulator. The device may be, for example, devoid of a log accumulator and may be configured to remove mandrels made in a single piece, rather than divided into two half-mandrels that are coupled together.

[0023] More generally, the present invention concerns a device for removing winding mandrels that comprises holding members for holding a log, from which a mandrel shall be removed, and an extraction unit comprising at least one extractor as defined above. In advantageous embodiments, the extraction unit is double and comprises two extractor members aligned according to the axis of the log, to remove two half-mandrels from two opposite ends of the log. In this case, each extractor member comprises an extractor as defined above.

[0024] The extraction device may be configured to handle a plurality of logs simultaneously; in this case, the extractor comprises a plurality of extractors of the type defined above, which act simultaneously on a plurality of mandrels inserted in a corresponding plurality of logs. If the mandrels are divided into two half-mandrels, two sets of extractors are provided, one for each end of the logs.

BRIEF DESCRIPTION OF THE DRAWING

[0025] The invention will be better understood by following the description below and the attached drawing, showing a non-limiting embodiment of the invention. More particularly, in the drawing:

Fig. 1 is a front view of a device for removing winding mandrels from logs of web material, comprising a log accumulator, according to an embodiment;

Fig. 2 is a simplified side view of the device of Fig. 1, wherein some parts have been omitted;

Fig. 3 shows an enlarged detail of Fig. 2;

Fig. 4 is an axonometric view of the device, wherein the accumulator has been omitted; Figs. 5 and 6 show enlargements of the two sides of the device of Fig. 5; Fig. 7 shows an enlarged detail of Fig. 5;

Fig. 8 shows an enlarged detail of Fig. 6;

Fig. 9 shows a further enlargement of Fig. 7;

Figs. 10(A) to 10(J) are side views of the operational sequence of a cycle for removing winding mandrels;

Figs. 11(A) to 11(D) are front views of the steps of the operational cycle;

Fig. 12 shows a step of discharging a log, from which the winding mandrel has not been extracted;

Figs. 13(A) to 13(C) show steps of transferring half-mandrels, removed from the logs, to a mandrel conveyor; and

Figs. 14 and 15 show the structure and the operation of the expandable pin for removing the winding mandrels.

DETAILED DESCRIPTION

[0008] [A device for removing winding mandrels from logs of web material, for example logs of tissue paper coming from a rewinder, is indicated as a whole with the reference number 1. The device comprises a log accumulator 3. In the illustrated embodiment, the log accumulator 3 comprises a bearing structure 4, on which an endless flexible member 5 is provided. The endless flexible member 5 consists of a pair of continuous chains 5A, 5B, driven around idler sprockets 7. In the diagram of the attached figures, the log accumulator 3 consists of a relatively short closed path of the endless flexible member 5, consisting of a single loop driven around two pairs (one for each chain) of idler sprockets. However, it should be understood that the log accumulator 3 can also be much larger and more complex than that illustrated. The log accumulator 3 can be configured, for example, as disclosed in W02012104881A1.

[0009] As particularly visible in Figs. 2 and 3, the endless flexible member 5 comprises a vertical rectilinear section, along which other members of the extracting device are arranged, described below.

[0010] Supports for the logs R are connected to the chains 5 A, 5B that constitute the endless flexible member 5. In the illustrated embodiment, the supports comprise channels 9 extending longitudinally between the two chains 5A, 5B according to a direction parallel to the axis of the logs R that are collected in the channels 9. The channels 9 are preferably arranged at a constant pitch along the extension of the endless flexible member consisting of the two chains 5 A, 5B. Each channel 9 is pivoted to the two chains 5 A, 5B around a respective longitudinal pivot axis 9A, which is parallel to the longitudinal extension of the channels 9.

[0011] The channels 9 may be removable from the endless flexible member 5, in order to be placed in different positions, preferably at constant pitch, as described again in W02012104881A1.

[0012] The movement of the continuous chains 5A, 5B along the closed path, indicated by the arrow f5, sequentially brings each channel 9 in front of a log loader 12, adapted to load individual logs R onto the channels 9. In the illustrated embodiment, the log loader 12 comprises either a chute 11 that receives the logs R from an upstream machine, such as a rewinder, not shown, or a tail sealer that receives the logs from a rewinder and seals the free edge of the wound web material, to prevent it from interfering with the subsequent operations. In the illustrated embodiment, the loader 12 further comprises a distributor 13, which rotates around an axis 13 A parallel to the axes of the logs R and the axes 9A of the channels 9 according to the arrow fl3. The distributor 13 is configured to distribute individual logs R coming from the chute 11 to the channels 9.

[0013] The log accumulator 3 is also provided with a log unloading device, not shown, that may be arranged on the descending branch of the chains 5A, 5B. If the log accumulator 3 is larger than that schematically shown, the chains 5A, 5B can define a large number of ascending and descending sections, and the one furthest downstream relative to the forward movement of the logs R along the log accumulator 3 may be provided with an unloading device, in a known manner.

[0014] The device 1 comprises, in addition to the log accumulator 3, a removal unit indicated as a whole with the reference number 15.

[0015] The removal unit 15 comprises at least one removal cradle, on which the logs R, from which the winding mandrel shall be removed, are arranged one at a time. In the illustrated embodiment, the removal unit 15 comprises four removal cradles, indicated with the reference number 17, which are substantially equal to, and arranged over, one another. The number of removal cradles 17 is merely indicative and may change, for example also depending on the size of the log accumulator 3, and more particularly on the height thereof, or on the cycle times to be achieved. [0016] The removal cradles 17 are aligned with one another in a direction parallel to a section of the closed path defined by the endless flexible member 5 (chains 5 A, 5B). Advantageously, in the illustrated embodiment, the cradles 17 are arranged one over the other along the vertical extension of the first ascending section of the endless flexible member 5. More specifically, the removal cradles 17 are arranged along the ascending section of the endless flexible member 5 that extends above the loader 12.

[0017] For the purposes that will be explained below, the removal cradles 17 are movable to selectively take: a receiving position, for receiving a log R from a respective channel 9 of the accumulator 3; a removal position, for removing the winding mandrel from the log R arranged in the removal cradle 17; and an unloading position for unloading the log R, devoid of the winding mandrel, from the removal cradle 17 to a channel 9 of the accumulator 3. The log R is preferably unloaded from the removal cradle 17 to the channel 9 from which it had been taken.

[0018] In the illustrated embodiment, the removal cradles 17 are integral with one another and carried by two slides 19, placed at opposite ends of the removal cradles 17. The slides 19 are omitted in Fig. 1 and shown in Figs. 2 to 9.

[0019] Each slide 19 is provided with a movement in horizontal direction, indicated with the double arrow fl9x, and a movement in vertical direction, indicated with the double arrow fl9y. The movement fl9x allows the slide 19 (and therefore the removal cradles 17) to move toward, and away from, the closed path of the chains 5 A, 5B and thus toward, and away from, the path of the channels 9. The vertical motion according to the arrow fl9y is parallel to the movement direction f9 of the channels 9 along the closed path defined by the chains 5 A, 5B.

[0020] The movement fl9x, fl9y is achieved by means of a carriage 20, on which the slides 19 are mounted. The carriage 20 comprises two flanks 21 , between which the removal cradles 17 and the slides 19 are positioned. More specifically, the slides 19 are mounted on the flanks 21 by means of guides 23 (in this case integral with the flanks 21) and shoes 25 (in this example integral with the slides 19), see in particular Figs. 7 and 8. The movement according to fl9x is achieved by means of a motor 27 (see Fig. 8) that drives pinions 29 meshing with racks 31 that are integral with the slides 19. A torsion bar 30 transmits motion from one flank 21 to the other.

[0021] The carriage 20 is mounted on vertical guides 33 integral with the structure 4 and is provided with a lifting and lowering movement, according to fl9y, along the vertical guides 33 controlled by a motor 34 through toothed belts or other flexible members 35. A torsion bar 37 is provided for transferring the motion from the motor 34 to the opposite flank.

[0022] Each removal cradle 17 is provided with a rotational movement about its own axis 17A of rotation, parallel to the axes 9A and the channels 9, as well as to the axes of the logs R arranged in the removal cradles 17.

[0023] In the illustrated embodiment, each removal cradle 17 is provided with an actuator 39 that controls the rotation of the respective cradle 17 around the cradle rotation axis 17A through a toothed belt or other endless flexible member 41, see in particular Figs. 6, 8. The actuator 39 may comprise, for example, an electric motor.

[0024] Each removal cradle 17 is provided with at least one pusher 45 co-acting with the pivoting channels 9. More specifically, in the illustrated example, each removal cradle 17 is provided, at its longitudinal ends, with two pushers 45. The pushers 45 are visible in particular in Fig. 3, while they are partially omitted in the remaining figures for the sake of clarity. The pushers 45 co-act with cams or stops 47 integral with the channels 9, also visible particularly in Fig. 3. As will be clarified below with reference to the operational sequence, when the removal cradle 17 rotates around the axis 17A in a clockwise direction (observing Fig. 3), the pushers 45 co-act with the respective cams 47, causing the respective channel 9, which is in the position adjacent to the removal cradle 17, to pivot in the opposite direction.

[0025] Each removal cradle 17 also comprises at least one stop adapted to hold axially the log R while the winding mandrel is removed therefrom. Since, in the illustrated embodiment, the winding mandrel is comprised of two halves, axially aligned with each other, each removal cradle 17 actually comprises two stops, adapted to axially hold the log R at both ends while the mandrel is being removed. The two stops are indicated with the reference number 49 and are provided with a movement toward, and away from, the log R controlled by an actuator, for example a cylinder-piston actuator, indicated with the reference number 51. The movement of the stops 49 is indicated with the double arrow f49 (see especially Figs. 6-9).

[0026] The removal unit 15 comprises an extractor adapted to remove the mandrels from the logs R arranged in the removal cradles 17. In the illustrated embodiment, which is configured to remove mandrels divided into two halves, the removal unit, i.e., the extractor thereof, comprises a first extraction member 63 and a second extraction member 63, wherein the first extraction member and the second extraction member are positioned on two opposite sides of the log accumulator 3, and therefore at opposite longitudinal ends of the removal cradles 17. Each extraction member 63 is movable on a respective guide 61. In the illustrated example, each guide 61 is double.

[0027] In the illustrated embodiment, each extraction member 63 comprises, for each removal cradle 17, a respective gripping element 65, adapted axially to engage a half-mandrel around which the log R, arranged in the respective removal cradle 17, is wound. Therefore, in the illustrated embodiment four gripping elements 65 are provided on each side of the set of removal cradles 17.

[0028] More specifically, in the illustrated embodiment, the removal unit 15 comprises, on each side of the device 1, a guide on which a respective extraction member 63 translates. For the sake of simplicity, both the extraction members 63 are shown in Fig. 1, while in Figs. 4 to 9 only one of the extraction members 63 is shown.

[0029] Actuators 67, for example electric motors, drive the horizontal movement of the extraction members 63 according to the double arrow f63, see Fig. 1. The movement can be transmitted, for example, through a rack and pinion mechanism, as schematically shown in the example illustrated in the attached drawing.

[0030] The device 1 also comprises a handler for each removal cradle 17. The handler is adapted to grip a winding mandrel engaged by the extractor after it has been removed from the log R arranged in the corresponding removal cradle 17. The handler may be configured to transfer the mandrel to a mandrel conveyor.

[0031] In the illustrated embodiment, since the winding mandrels are divided into two halves, each of which is removed from one end of the respective log, the handler is double and comprises two handling members, one on each side of the device 1.

[0032] More specifically, Fig. 4 shows a handling member 71. The symmetric handling members on the other side of the device 1 are omitted for simplicity of representation. The handling members 71 are provided with a horizontal movement, orthogonal to the guides 61 and schematically indicated with the double arrow f71. The movement according to the double arrow f71 allows each half-mandrel, removed from the respective log, to be engaged and transferred to a mandrel conveyor, schematically indicated with the reference number 73 and shown only in Figs. 13(A) to 13(C).

[0033] An operational cycle of the device described above is illustrated in Figs. 10 to 12 and will be described in detail below.

[0034] The first step of the removing cycle is shown in Fig. 10(A). Seven logs R are arranged in the accumulator 3. It should be understood that generally also the remaining channels 9 may be full. The removal cradles 17 are placed at a certain distance (in the horizontal direction) from the feed path defined by the chains 5 A, 5B. On the chute 11, more logs R are arranged that will be loaded in the subsequent steps. In Fig. 10(B), the slides 19 that support the removal cradles 17 have been approached to the ascending rectilinear section of the closed path of the channels 9, defined by the endless flexible member 5 (chains 5A, 5B). The mutual position in the vertical direction of the removal cradles 17 and the channels 9 is such that the approaching movement causes the channels 9 to pivot around the axes 9A due to the interaction between the cams or stops 47 and the pushers 45. Consequently, the logs R that are in the four channels 9 co-acting with the four removal cradles 17 are unloaded from the channels 9 and log into the removal cradles 17, as shown in Fig. 10(C).

[0035] In the following step, shown in Fig. 10(D), the slides 19 move away from the ascending path of the channels 9, and thus allow the channels 9 to return to the rest position, and the chains 5A, 5B to move forward, so that the subsequent logs can move upward, without interfering with the removal cradles 17 and the logs lying therein.

[0036] At this point, the two half-mandrels, that constitute each winding mandrel for the logs R arranged in the removal cradles 17, are removed by the extraction members 63, in the manner described below with reference to Figs. 11(A)-11(E).

[0037] After the half-mandrels have been removed from the four logs R arranged in the removal cradles 17, the cradles translate upward as shown in Fig. 10(E), see the arrows in the figure. This movement brings the removal cradles 17, where the logs R, from which the winding mandrel has been removed, are arranged, in alignment with the channels 9, from which these logs had previously been unloaded (step of Fig. 10(C)). In fact, these channels are empty, while the channels below are occupied by logs R, from which the winding mandrels have not removed yet. [0038] In the step of Fig. 10(F), the slides 19 are approached to the path of the channels 9. In this step, the mutual position, in the vertical direction, of the channels 9 and the removal cradles 17 is such that the pushers 45 and the cams 47 do not co-act with one another, and the channels 9, constituting the supports for the logs R of the accumulator 3, remain in the rest position.

[0039] In the subsequent step of Fig. 10(G), the removal cradles 17 rotate in such a direction as to unload the respective logs R, devoid of the winding mandrels, onto the channels 9 from which they had previously been taken. In Fig. 10(H), the logs R devoid of the mandrels have been transferred from the removal cradles 17 to the channels 9, and the slides 19, with the respective empty removal cradles 17, move away in the horizontal direction and then return downward along the feed path of the channels (see Figs. 10(1) and 10(J)) so as to be arranged again in the position of Fig. 10(A). In Fig. 10(J), the logs Rl, R2, R3, and R4 are devoid of the winding mandrel, while the logs R5-R11 still contain the winding mandrel. In the next cycle, the mandrels of the logs R5, R6, R7, and R8 will be extracted, with the same cycle as previously described.

[0040] The mandrels, or more precisely the two half-mandrels that (coupled together and axially aligned) form each winding mandrel, are removed preferably when the removal cradles 17 are in the position of Fig. 10(D), with the operations schematically illustrated in the sequence of Figs. 11(A) to 11(E).

[0041] In Fig. 11(A) the logs R, from which the mandrels shall be removed, are loaded onto the removal cradles 17. The two extraction members 63 are spaced from the removal cradles 17. The stops 49 are spaced from each other sufficiently to allow the insertion of the logs R into the removal cradles 17.

[0042] In the following step, illustrated in Fig. 11(B), the stops 49 are approached to the axial ends of the logs R in each removal cradle 17, to hold the log in a central position during the subsequent removal step. In alternative embodiments, the stops 49 may be omitted if the friction force that must be overcome to remove the two half-mandrels from the log R is equal or approximately equal for the two half-mandrels. In further embodiments, the stops 49 are fixed. In this case, even if the friction forces on the two half-mandrels are not balanced, the longitudinal movement of the log due to the traction exerted on the two mandrels is limited and does not compromise the proper removal of the two half-mandrels. [0043] In Fig. 11(C) the two extraction members 63 approach the removal cradles 17 and the eight gripping elements 65 are inserted into the two half-mandrels of each of the four logs R arranged in the four removal cradles 17.

[0044] In Fig. 11(D), the two extraction members 63 have moved away from the removal cradles 17 and have removed, from each log R, the two half-mandrels Ml, M2, which in this step remain engaged to the gripping elements 65, an embodiment of the structure and operation of which will be described in detail below. During the removal step, a downward- directed force can be generated between each gripping element and the respective halfmandrel, for example to facilitate the transfer of an adhesive, previously applied to the mandrel consisting of the two half-mandrels Ml, M2 before the beginning of winding, from the half-mandrels to the inner coils of the web material. The downward thrust, which can be realized for example by lifting the slides 19, is also useful to facilitate the mutual gluing of the innermost coils of the web material forming each log.

[0045] In this step, each half-mandrel Ml, M2 faces a respective set of handling members 71, which engage the half-mandrels Ml, M2. In the following step (Fig. 11(E)), the gripping elements 65 are removed from the mandrels, with an extra-stroke movement of the extraction members, so that each half-mandrel Ml, M2 remains engaged only to the respective handling member 71. At this point, with a movement orthogonal to the plane of Fig. 11(E), the handling members 71 transfer the half-mandrels to the mandrel conveyor 73, which recycles the half-mandrels sending them toward a rewinder, not shown.

[0046] In this step, as shown in Fig. 11(E), the stops 49 are moved away from the ends of the logs R, to allow the subsequent transfer thereof to the channels 9, from which they had been taken in the initial step of the cycle.

[0047] Figs. 13(A) to 13(C) show a side view of one of the handling members 71 and the movement with which it engages the half-mandrels Ml removed from the logs R, to transfer them to the mandrel conveyor 73 with a movement according to the arrow f71. The reference number 74 indicates supports for the half-mandrels along a closed path of the mandrel conveyor 73.

[0048] Along the half-mandrel removal paths, or in any suitable position, sensors or detectors may be provided, adapted to check whether the half-mandrels have been properly removed from the respective logs. This makes it possible to discard the logs R, in which one or both half-mandrels Ml, M2 have remained. Any suitable system can be used for this purpose. For example, a vision system may be provided, with one or more cameras detecting the presence or absence of half-mandrels in the extracted position (Fig.11(E)). If the detection system detects that one or both of the half-mandrels Ml, M2 have not been removed from any of the logs R arranged in the removal cradles 17, these logs are discarded from the system and not transferred back to the accumulator 3, in order to prevent the half-mandrels from entering the downstream machines, e.g. severing machines that cut the logs into logs of shorter axial length.

[0049] Instead of the vision system, a first sensor may be used, positioned along each of the paths for removing the half-mandrels, and adapted to detect the presence or absence of the mandrel or half-mandrel in the space in front of each first sensor. The first sensor may be, for example, a photocell, or a capacitive sensor. The first sensor can be arranged in a position adjacent to each removal cradle 17. In particular, each first sensor can be arranged in an initial section of the removal path. In this way, by read-activating the photocell during the removal cycle, in a first time interval it is possible to detect the presence, or the passage, of the mandrel, and, at the end of the removal cycle, it is possible to detect the absence of the mandrel. This ensures that the entire mandrel has passed in front of the sensor and that therefore the half-mandrel is no longer at least partially inserted into the log R.

[0050] To this end, in some embodiments, the reading by the sensor is related to the position of the respective extraction member 63 during the removal cycle. In this way, the premature and unintentional disengagement of the gripping element 65 from the respective half-mandrel is detected. The first sensor may be arranged along the trajectory of removal of the mandrel or half-mandrel, between the stop 49 and the handling member 71.

[0051] Fig. 12 shows a step of discarding a log R, from which one or both half-mandrels have not been removed. In the example, the log R arranged in the uppermost removal cradle is discarded through a rotation according to fl7x, in the opposite direction to the direction of rotation with which the logs R are transferred from the removal cradles 17 to the channels 9. The reference number 90 indicates a discard chute, and the reference number 92 indicates a removal conveyor, if any, for removing the discarded logs. The conveyor 92 may be a belt conveyor, provided with a movement parallel to the axis of the logs R. Since the event of a log being discarded is very rare, it is possible to accumulate the discarded logs in a static hopper rather than removing them through a conveyor. [0052] In some embodiments, a second sensor may be associated with each extraction member 63. The second sensor, for example a photocell, is adapted to detect that the gripping elements 65 have been actually removed from the half-mandrel at the end of the removal cycle. To this end, each second sensor is arranged in such a position along each removal path that it does not detect the presence of the gripping element 65 once the gripping element 65 has been removed from the respective half-mandrel and the latter is supported by the respective handling member 71.

[0053] In other words, the second sensor is adapted to detect the presence of the respective gripping element 65 as long as it remains inserted in the respective half-mandrel, and is adapted to detect the absence of the gripping element 65 at the end of the removal cycle once the gripping element 65 has been disengaged from the respective half-mandrel. This ensures that the disengagement of a gripping element 65 from the respective half-mandrel has occurred correctly and that a problem has not occurred whereby a gripping element 65 remains constrained to the half-mandrel, dragging it to an incorrect position. The second sensor may be positioned along the removal path, between the handling member 71 and the end-travel position of the gripping element 65.

[0054] Additional sensors may be used along each extraction path to verify the correct positioning of each half-mandrel at the end of the removal cycle.

[0055] A third sensor, for example a photocell, may be used to detect an incorrect loading of the logs R from the channels 9 to the removal cradles 17. In this case, the sensor is positioned to detect the presence/absence of the logs R in the space identified between the channels 9 and the removal cradles 17. In particular, after the step where a log R is received in the removal cradles 17, the third sensor shall detect an empty space, indicating that none of the logs R got stuck during the loading or receiving step, i.e., none of the logs has remained partly in the channels 9 and partly in the removal cradles 17. All the sensors described above are connected to a control unit, not shown, which can generate alarms, and/or stop the step of loading or unloading the logs R and/or the removal step. In particular, by means of at least the signal generated by at least one of the first sensors and second sensors, if a mandrel or half-mandrel is detected not properly removed from a log R, the control unit can control the discard of the corresponding log R as illustrated and described with reference to Fig. 12.

[0056] An embodiment of the gripping elements 65 and the operation thereof are described below with reference to Figs. 14 and 15.

[0057] In this embodiment, each gripping element 65 comprises a pin 65.1 that comprises a conical distal portion 65.2 integral with a stem or rod 65.3. At the opposite end with respect to the conical distal portion 65.2, each gripping element 65 comprises an actuator 65.4. In the illustrated embodiment, the actuator 65.4 is a cylinder-piston actuator, for example of a hydraulic or electric type, or preferably a pneumatic actuator. In some embodiments, the cylinder-piston actuator 65.4 is a single-acting cylinder-piston actuator. In other embodiments, the cylinder-piston actuator 65.4 is a double-acting actuator.

[0058] The rod or stem 65.3 is guided in a guide 65.6. One or more elastically deformable annular bodies 65.7 are provided between the part of the guide 65.6 facing the distal end of the rod 65.3 and the conical distal portion 65.2. Three elastically deformable annular bodies

65.7 are provided in the illustrated example. Each elastically deformable annular body is mounted idly on the rod 65.3 so as to be able to slide relative to the rod. Moreover, each elastically deformable annular body 65.7 may have a cylindrical or toroidal shape, with an axis coincident with the axis of the rod 65.3 and a hollow interior, forming the axial passage for the rod 65.3.

[0059] A spacer 65.8 is interposed between adjacent elastically deformable annular bodies 65.7. Each spacer 65.8 may be approximately cylindrical and has a through-hole, into which the rod 65.3 is inserted. Each spacer 65.8 is free to slide relative to the rod 65.3. The spacers

65.8 may be rigid, contrary to the elastically deformable annular bodies 65.7. It should be understood that the terms "rigid" and "elastically deformable" are relative terms and refer to the conditions of use of the described device. Therefore, the spacers 65.8 are rigid in the sense that they do not undergo detectable compressive deformation under normal use conditions, while the elastically deformable annular bodies 65.7 compress axially and expand radially during use, in the manner and for the purpose described below.

[0060] The set of spacers 65.8 and elastically deformable annular bodies 65.7 is arranged between a radial stop formed by the conical distal portion 65.2 and a radial stop formed by the guide 65.6.

[0061] In rest conditions, when the rod 65.3 is in the extracted position, as shown in Fig. 14, the elastically deformable annular bodies 65.7 are in an undeformed condition, i.e., in a condition of minimum energy and minimum radial dimension. The outer diameter of the elastically deformable annular bodies 65.7, of the conical distal portion 65.2, and of the spacers 65.8 is such that in this condition the gripping element 65 can be inserted into the half-mandrel Ml (or M2), on which a log R is wound.

[0062] Once the insertion position has been reached (Fig. 14), the rod 65.3 with the conical distal portion 65.2 can be retracted into the position of Fig. 15. Since the elastically deformable annular bodies 65.7 and the spacers 65.8 are free to slide on the rod 65.3, they remain in a substantially unchanged position relative to the half-mandrel Ml (M2) and the log. The contraction caused by the retraction of the radial stop formed by the conical distal portion 65.2 causes the axial contraction of the elastically deformable annular bodies 65.7 and the consequent radial expansion thereof. As a result of this deformation, the elastically deformable annular bodies 65.7 are pressed against the inner surface of the half-mandrel. The friction generated between the elastically deformable annular bodies 65.7 and the inner surface of the half-mandrel Ml (or M2) is sufficient to remove the half-mandrel from the log R by retracting the respective extraction member 63.

[0063] Essentially, each of the two extraction members 63 therefore comprises an expandable element that serves to engage by friction from the inside the respective hollow half-mandrel. The use of the elastically deformable annular bodies 65.8 described above avoids the need to use expandable elements of the hydraulic or pneumatic type inside the mandrels. This makes the system of mutual engagement between the extraction member and the mandrel significantly simpler, avoids the need for working fluid conduits, and avoids problems arising from possible leakage or seepage.

[0064] The elastically deformable annular bodies can be produced at low cost and can be easily replaced in case of wear, by simply removing the conical distal portion 65.2, which for this purpose may be for example screwed to the rod 65.3.

[0065] Moreover, this avoids to engage the half-mandrel from the inside and the outside as occurs in clamp-type gripping members, which can damage the half-mandrel or mandrel. Moreover, by acting only by friction from inside the half-mandrel, it is possible to use mandrels that do not exceed the length of the log R, since there is no need to have an outer surface for gripping by a clamp-type gripping member.

[0066] Although a device for removing winding mandrels formed by two axially coupled half-mandrels has been particularly described, it should be understood that a fully equivalent machine can be realized also in the case where the winding mandrel is a single tubular element.

[0067] In this case, only one extraction member 63 is provided, positioned on one side of the removal cradle 17, or of each removal cradle 17. The extraction stroke of the gripping element(s) 65 is obviously double with respect to what previously described, as the entire mandrel shall be removed and not just one half thereof.

Claims

Claims

1. An extractor for removing winding mandrels from logs of wound web material, wherein the extractor comprises an expandable pin that is configured to be inserted into the winding mandrel and to engage the winding mandrel by expansion; and wherein the expandable pin comprises a rod and at least one annular body surrounding the rod, the annular body being radially expandable around the rod, so as to engage, by pressure, an inner surface of the winding mandrel.

2. The extractor of claim 1, wherein the at least one annular body comprises a plurality of annular bodies arranged sequentially along the axial extension of the rod, each annular body being radially expandable around the rod, so as to engage, by pressure, the inner surface of the winding mandrel.

3. The extractor of claim 2, wherein the annular bodies are arranged on the rod, free to slide relative thereto.

4. The extractor of claim 3, comprising, between adjacent annular bodies, a rigid annular element, slidingly mounted on the rod.

5. The extractor of any one of the preceding claims, wherein each annular body is elastically deformable in axial and radial directions, a reduction in the length in axial direction causing an expansion of the annular body in the radial direction.

6. The extractor of claim 5, wherein each annular body has a minimum energy configuration corresponding to a maximum axial dimension and a minimum radial dimension.

7. The extractor of any one of the preceding claims, wherein the rod is housed in a sliding seat so as to slide axially in the sliding seat under the control of an expansion actuator, in order to move between a removal position and a retracted position relative to the sliding seat.

8. The extractor of claim 7, wherein the rod comprises a radial end stop, such that the retraction of the rod relative to the sliding seat causes the rod to slide within each annular body and each annular body to contract axially and to expand radially.

9. A device for removing winding mandrels from logs of wound web material; wherein the device comprises holding members for holding a log, from which a mandrel shall be extracted, and an extraction unit comprising at least one extractor according to one or more of the preceding claims.

10. The device of claim 9, comprising a plurality of extractors according to one or more of the preceding claims, configured to engage and to extract simultaneously a plurality of mandrels from a plurality of logs.