Wrapping device for product wrappers

Abstract

A device for wrapping product wrappers including a winder, the winder including a gripper mechanically connected to a tubular shaft rotatable about and translatable along an approach axis, the gripper being rotatable and translatable integrally with the tubular shaft; an actuating rod active on the gripper and movable along an actuating axis, the actuating rod being movable along the actuating axis with respect to the tubular shaft and rotationally constrained to the tubular shaft, wherein the gripper is rotatable and movable following a translation of the actuating rod along the actuating axis; a first electric motor active on the actuating rod to translate the actuating rod along the actuating axis; and a second electric motor active on the tubular shaft to translate the tubular shaft along the approach axis. The device further includes a control unit configured to drive the first electric motor and the second electric motor.

Claims

1. A wrapping device for product wrappers comprising: a winder comprising: a gripper mechanically connected to one end of a tubular shaft, wherein said tubular shaft is rotatable about an approach axis (A) and translatable along said approach axis (A), and wherein said gripper is rotatable and translatable integrally with said tubular shaft; an actuating rod, configured to act on said gripper, sliding along an actuating axis (B) parallel to, or coinciding with, said approach axis (A), wherein said actuating rod slides along said actuating axis (B) with respect to said tubular shaft and is rotationally constrained to said tubular shaft, and wherein said gripper is openable and closable in response to a translation of said actuating rod along said actuating axis (B); a first electric motor operating on said actuating rod to translate said actuating rod along the actuating axis (B); a second electric motor operating on said tubular shaft to translate said tubular shaft along the approach axis (A); said device further comprising a control unit configured to drive the first electric motor and the second electric motor; wherein said winder comprises a first fork connected to a drive shaft of the first electric motor and constrained in translation along the actuating axis (B) to said actuating rod; said actuating rod being rotatable about said actuating axis (B) with respect to said first fork.

2. The wrapping device according to claim 1, comprising a third electric motor configured to act on said tubular shaft to rotate said tubular shaft about the approach axis (A); said control unit being configured to drive the third electric motor.

3. The wrapping device according to claim 2, comprising a transmission shaft connected to said third electric motor; a pinion being keyed to said transmission shaft to rotate with said transmission shaft; a spur gear being keyed on said tubular shaft and being directly or indirectly geared with said pinion.

4. The wrapping device according to claim 1, wherein said winder comprises a first control rod having a first end hinged to the first fork and a second end connected to a rotating drive shaft of the first electric motor; said first control rod moving the actuating rod along the actuating axis (B).

5. The wrapping device according to claim 4, wherein said drive shaft of the first electric motor is driven to rotate in a first angular direction to translate the actuating rod in a first direction along the actuating axis (B), and to rotate in a second angular direction opposite the first and translate the actuating rod in a second direction along the actuating axis (B).

6. The wrapping device according to claim 1, wherein said winder comprises a second fork connected to a drive shaft of said second electric motor and constrained in translation along the approach axis (A) to said tubular shaft; said tubular shaft being rotatable about said approach axis (A) with respect to said second fork.

7. The wrapping device according to claim 6, wherein said winder comprises a second control rod having a first end hinged to the second fork and a second end connected to a rotating drive shaft of the second electric motor; said second control rod moving the tubular shaft along the approach axis (A).

8. The wrapping device according to claim 7, wherein said drive shaft of the second electric motor is driven to rotate in a first angular direction to translate the tubular shaft in a first direction along the approach axis (A), and to rotate in a second angular direction opposite the first direction and translate the tubular shaft in a second direction along the approach axis (A).

9. The wrapping device according to claim 1, comprising a user data entry interface configured to receive at least one input data (ID) representative of a desired operating parameter (DOP) of the gripper.

10. The wrapping device according to claim 9, wherein said control unit is configured to determine a law of motion of the gripper starting from said at least one desired operating parameter (DOP).

11. The wrapping device according to claim 10, wherein said control unit is configured to interpolate said at least one desired operating parameter (DOP) with preset operating parameters (POP) and to determine said law of motion of the gripper from a result of said interpolation.

12. The wrapping device according to claim 10, wherein said control unit is further configured to determine, from said law of motion of the gripper, a first law of motion of the actuating rod and a second law of motion of the tubular shaft.

13. The wrapping device according to claim 12, wherein said control unit is configured to generate a first control signal (CS1) representative of the first law of motion and to send it to a driver of the first electric motor and to generate a second control signal (CS2) representative of the second law of motion and to send it to a driver of the second electric motor.

14. The wrapping device according to claim 1, further comprising a further winder comprising: a further gripper mechanically connected to one end of a further tubular shaft, wherein said further tubular shaft is rotatable about a further approach axis and translatable along said further approach axis and wherein said further gripper is rotatable and translatable integrally with said further tubular shaft; a further actuating rod, configured to act on said further gripper, sliding along a further actuating axis parallel to, or coinciding with, said further approach axis, wherein said further actuating rod is slidable along said further actuating axis with respect to said further tubular shaft and is rotationally constrained to said further tubular shaft, and wherein said further gripper is openable and closable in response to a translation of said further actuating rod along said further actuating axis; a further first electric motor active on said further actuating rod to translate said further actuating rod along said further actuating axis; a further second electric motor operating on said further tubular shaft to translate said further tubular shaft along the further approach axis; said control unit being configured to drive the further first electric motor and the further second electric motor.

15. A wrapping device for product wrappers comprising: a winder comprising: a gripper mechanically connected to one end of a tubular shaft, wherein said tubular shaft is rotatable about an approach axis (A) and translatable along said approach axis (A), and wherein said gripper is rotatable and translatable integrally with said tubular shaft; an actuating rod, configured to act on said gripper, sliding along an actuating axis (B) parallel to, or coinciding with, said approach axis (A), wherein said actuating rod slides along said actuating axis (B) with respect to said tubular shaft and is rotationally constrained to said tubular shaft, and wherein said gripper is openable and closable in response to a translation of said actuating rod along said actuating axis (B); a first electric motor operating on said actuating rod to translate said actuating rod along the actuating axis (B); a second electric motor operating on said tubular shaft to translate said tubular shaft along the approach axis (A); said device further comprising a control unit configured to drive the first electric motor and the second electric motor; said device further comprising a user data entry interface configured to receive at least one input data (ID) representative of a desired operating parameter (DOP) of the gripper, wherein said control unit is configured to determine a law of motion of the gripper starting from said at least one desired operating parameter (DOP) and wherein said control unit is configured to interpolate said at least one desired operating parameter (DOP) with preset operating parameters (POP) and to determine said law of motion of the gripper from a result of said interpolation.

16. A wrapping device for product wrappers comprising: a winder comprising: a gripper mechanically connected to one end of a tubular shaft, wherein said tubular shaft is rotatable about an approach axis (A) and translatable along said approach axis (A), and wherein said gripper is rotatable and translatable integrally with said tubular shaft; an actuating rod, configured to act on said gripper, sliding along an actuating axis (B) parallel to, or coinciding with, said approach axis (A), wherein said actuating rod slides along said actuating axis (B) with respect to said tubular shaft and is rotationally constrained to said tubular shaft, and wherein said gripper is openable and closable in response to a translation of said actuating rod along said actuating axis (B); a first electric motor operating on said actuating rod to translate said actuating rod along the actuating axis (B); a second electric motor operating on said tubular shaft to translate said tubular shaft along the approach axis (A); said device further comprising a control unit configured to drive the first electric motor and the second electric motor; said device further comprising a third electric motor configured to rotate the tubular shaft and the actuating rod; said third electric motor being connected to a transmission shaft, wherein the transmission shaft extends between the winder and a further winder comprising a further gripper.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further features and advantages of the present invention will become clearer from the following detailed description of a preferred embodiment thereof, with reference to the appended drawings and provided by way of indicative and non-limiting example, in which:

(2) FIG. 1 is a schematic perspective view of a wrapping device for product wrappers in accordance with the present invention in an opening condition;

(3) FIG. 2 is a schematic perspective view of a detail of the wrapping device of FIG. 1;

(4) FIG. 3 is a schematic perspective view of some parts of the detail of the wrapping device of FIG. 2;

(5) FIG. 4 is a schematic perspective view of further parts of the detail of the wrapping device of FIG. 2;

(6) FIG. 5 depicts a schematic sectional view in the plane V-V of a part of the wrapping device of FIG. 1; and

(7) FIG. 6 is a block diagram representative of some components of the wrapping device for product wrappers in accordance with the present invention.

DETAILED DESCRIPTION

(8) In the appended figures, a wrapping device for product wrappers in accordance with the present invention is generically referred to by the numerical reference 1.

(9) The device 1 comprises a winder 10 shown on the left in FIG. 1 and a further winder 10a shown on the right in FIG. 1.

(10) Arranged between the winder 10 and the further winder 10a is a feeder of products to be wrapped 12 (depicted only schematically) rotating about a rotation axis X. The feeder of products to be wrapped comprises a plurality of seats (not illustrated) in each of which a corresponding product to be wrapped, partially wrapped by a wrapper material, is arranged. Such wrapper material needs to be wound at one or both ends to form a twist or a pair of twists. The rotation of the feeder of products to be wrapped sequentially places the partially wrapped products between winder 10 and the further winder 10a.

(11) The winder 10 and the further winder 10a are configured to make a corresponding twist on the product wrapper.

(12) The winder 10 and the further winder 10a are arranged facing each other with the product feeder 12 arranged between them.

(13) The winder 10 and the further winder 10a are structurally identical to each other, except as explicitly described below, and are arranged symmetrically with respect to an ideal plane perpendicular to the rotation axis X of the product feeder 12.

(14) Therefore, what is described in relation to the winder 10 is identically valid for the further winder 10a. The components of the winder 10 are also present in the further winder 10a and are depicted in FIG. 1, where necessary, with corresponding reference numbers followed by the letter a.

(15) The winder 10 comprises a gripper 20 mounted at one end 21 of a tubular shaft 22. The tubular shaft 22 is mounted inside a containment body 23 from which the end 21 of the tubular shaft 22 emerges.

(16) The further gripper 20a, the further tubular shaft 22a, the end 21a of the further tubular shaft 22a and the further containment body 23a of the further winder 10a are shown in FIG. 1.

(17) As better shown in FIG. 3, the tubular shaft 22 is rotatably mounted inside the containment body 23 (not shown in FIG. 3) to rotate about an approach axis A.

(18) An actuating rod 24 is inserted inside the tubular shaft 22, which is rotationally integral with the tubular shaft 22 through, for example, a pin or shape coupling.

(19) The actuating rod 24 also rotates about the approach axis A.

(20) The tubular shaft 22 also slides along the approach axis between a rearward and forward position. In the rearward position, the end 21 of the tubular shaft 22 is distanced from the feeder 12 of products to be wrapped, and in the forward position the end 21 of the tubular shaft 22 is moved closer to the feeder 12 of products to be wrapped.

(21) The actuating rod 24 slides along an actuating axis B coincident with the approach axis A. The actuating rod 24 slides inside the tubular shaft 22 and with respect to the tubular shaft 22. The actuating rod 24 slides along the actuating axis B between a rearward and forward position. When the actuating rod 24 is in the forward position, one end 25 of the actuating rod 24 protrudes more from the end 21 of the tubular shaft 22 with respect to when the actuating rod 24 is in the rearward position.

(22) A first electric motor 30 is provided to drive the translation of the actuating rod 24 along the actuating axis B with respect to the tubular shaft 22.

(23) A second electric motor 31 is provided to drive the translation of the tubular shaft 22 along the approach axis A.

(24) A third electric motor 32 is provided to drive the rotation of the tubular shaft 22 and the actuating rod 24 therewith.

(25) As shown in FIG. 2, the third electric motor is connected to a transmission shaft having a rotation axis C parallel to and spaced from the approach axis A.

(26) In the preferred embodiment of the invention, a drive shaft of the third electric motor 32 is connected to a speed reducer 33. The speed reducer 33 is connected via an input shaft to the transmission shaft of the third electric motor 32 and via an output shaft to the transmission shaft 40. The function of the speed reducer 33 is to rotate the transmission shaft 40 at a different speed (preferably lower) than the rotation speed of the motor shaft of the third electric motor 32.

(27) A pinion 41 is keyed to the transmission shaft 40, which rotates integrally with the transmission shaft 40. The pinion 41 is geared with a toothed roller 42 having a rotation axis D parallel to the rotation axis of the transmission shaft 40.

(28) The toothed roller 42 is also geared with a gear 43 keyed to the tubular shaft 22.

(29) The rotation of the transmission shaft 40 results in a rotation of the tubular shaft 22.

(30) Both the pinion 41, toothed roller 42 and gear 43 are spurred, so that gear 43 can translate along the approach axis A (together with the tubular shaft 22) without losing engagement with the toothed roller 42. The dimension along the rotation axis D of the toothed roller 42 is greater than the maximum translation length of the tubular shaft 22 along the approach axis A.

(31) The third electric motor 32 also drives the rotation of the further tubular shaft 22a and the further actuating rod of the further winder 10a.

(32) In this regard, as shown in FIG. 1, the transmission shaft 40 extends between the winder 10 and the further winder 10a until it reaches the further winder 10a. At the further winder 10a, the transmission shaft comprises a further pinion geared with a further toothed roller which is geared with a further pinion keyed to the further tubular shaft 22a.

(33) As described above, a first electric motor 30 is provided to drive the actuating rod 24 along the actuating axis B.

(34) In this regard, the first electric motor 30 is active on a first fork 50 which is integral along the actuating axis to the actuating rod 24. The actuating rod 24 rotates about the actuating axis B with respect to the first fork 50. The first fork 50 comprises a through opening slidingly crossed by the actuating rod 24. The first fork comprises a shoulder in sliding contact against two abutments 61 integral with the actuating rod 24 and placed on the opposite side with respect to the through opening.

(35) When the first fork 50 is moved by the first electric motor 30 along the actuating axis B, the shoulder of the fork exerts a force against one of the two abutments 61 integral with the actuating rod 24, causing the actuating rod to translate along the actuating axis B.

(36) Similarly, the second electric motor 31 is active on a second fork 51 which is integral along the approach axis A to the tubular shaft 22. The tubular shaft 22 rotates about the approach axis A with respect to the second fork 51. The second fork 51 comprises a through opening slidingly crossed by the tubular shaft 22. The second fork 51 comprises a shoulder in sliding contact against two abutments 62 integral with the actuating shaft 22 and placed on the opposite side with respect to the through opening.

(37) When the second fork 51 is moved by the second electric motor 31 along the approach axis A, the shoulder of the second fork exerts a force against one of the two abutments 62 integral with the tubular shaft 22, causing the translation of the tubular shaft 22 along the approach axis A. During such translation, the pinion 43 translates with respect to the toothed roller 42 without losing engagement therewith.

(38) In a first embodiment shown in the accompanying figures, the first electric motor drives the first fork 50 via a first control rod 53. In this embodiment, the first electric motor 30 comprises a rotating drive shaft. The first electric motor 30 generates a mechanical moment on the rotating drive shaft, rotating the latter.

(39) The first control rod 53 comprises a first end 54 hinged to the first fork 50 around a hinge axis perpendicular to the actuating axis B.

(40) The first control rod 53 comprises a second end 55 opposite the first end 55 stably connected to the output shaft of a speed reducer 56. The speed reducer 56 comprises an input shaft connected to the drive shaft of the first electric motor 30. The function of the speed reducer 56 is to rotate the first control rod 53 at a different speed (preferably lower) than the rotation speed of the drive shaft of the first electric motor 30.

(41) When the first electric motor 30 is driven to rotate in a first angular direction, the first control rod 53 rotates concordantly in the same angular direction. The first control rod 53 sets the first fork 50 in motion in a first direction along the actuating axis B. Such a first direction is directed towards the forward position of the actuating rod 24. The first fork 50 drags the actuating rod 24 towards the forward position in translation.

(42) When the first electric motor 30 is driven to rotate in a second angular direction, the first control rod 53 rotates concordantly in the same angular direction. The first actuating rod 53 sets the first fork 50 in motion in a second direction along the actuating axis B. Such a second direction is directed towards the rearward position of the actuating rod 24. The first fork 50 drags the actuating rod 24 towards the rearward position in translation.

(43) In the first embodiment, the second electric motor 31 drives the second fork 51 via a second control rod 57. The second electric motor 31, similar to the first electric motor 30, comprises a rotating drive shaft. The second electric motor 31 generates a mechanical moment on the rotating drive shaft, rotating the latter.

(44) The second control rod 57 comprises a first end 58 hinged to the second fork 51 about a hinge axis perpendicular to the approach axis A.

(45) The second control rod 57 comprises a second end 59 opposite the first end 58 permanently connected to the output shaft of a speed reducer 60. The speed reducer 60 comprises an input shaft connected to the drive shaft of the second electric motor 31. The function of the speed reducer 60 is to set the second control rod 57 rotating at a different speed (preferably lower) than the rotation speed of the drive shaft of the second electric motor 31.

(46) When the second electric motor 31 is driven to rotate in a first angular direction, the second control rod 57 rotates concordantly in the same angular direction. The second control rod 57 sets the second fork 51 in motion in a first direction along the approach axis A. Such a first direction is directed towards the forward position of the tubular shaft 22. The second fork 51 drags the tubular shaft 22 towards the forward position in translation.

(47) When the second electric motor 31 is driven to rotate in a second angular direction, the second control rod 57 rotates concordantly in the same angular direction. The second control rod 57 sets the second fork 51 in motion in a second direction along the approach axis A. This second direction is directed towards the rearward position of the tubular shaft 22. The second fork 51 drags the tubular shaft 22 towards the rearward position in translation.

(48) In a second embodiment not illustrated, the first electric motor is a linear electric motor and comprises a translatable drive shaft. The linear electric motor produces a force on the motor shaft which sets the motor shaft in motion along a straight trajectory, either in a first direction or in a second direction opposite to the first.

(49) The translation direction of the drive shaft is parallel and preferably coincident with the actuating axis B.

(50) The drive shaft is connected, either directly or via a return, to the first fork 50.

(51) When the first electric motor 30 is driven to translate the drive shaft in a first direction, the drive shaft sets the first fork 50 in motion in a first direction along the actuating axis B. Such a first direction is directed towards the forward position of the actuating rod 24. The first fork 50 drags the actuating rod 24 towards the forward position in translation.

(52) When the first electric motor 30 comes to translate the drive shaft in a second direction, the drive shaft sets the first fork 50 in motion in a second direction along the actuating axis B. Such a second direction is directed towards the rearward of the actuating rod 24. The first fork 50 drags the actuating rod 24 towards the rearward position in translation.

(53) In the second embodiment, the second electric motor is a linear electric motor and comprises a translatable drive shaft. The linear electric motor produces a force on the motor shaft which sets the motor shaft in motion along a straight trajectory, either in a first direction or in a second direction opposite to the first.

(54) The translation direction of the drive shaft is parallel and preferably coincident with the approach axis A.

(55) The drive shaft is connected, either directly or via a return, to the second fork 51.

(56) When the second electric motor 31 is driven to translate the drive shaft in a first direction, the drive shaft sets the second fork 51 in motion in a first direction along the approach axis A. Such a first direction is directed towards the forward position of the tubular shaft 22. The second fork 51 drags the tubular shaft 22 towards the forward position in translation.

(57) When the second electric motor 31 comes to translate the drive shaft in a second direction, the drive shaft sets the second fork 51 in motion in a second direction along the approach axis A. Such a second direction is directed towards the rearward position of the tubular shaft 22. The second fork 51 drags the tubular shaft 22 towards the rearward position in translation.

(58) The gripper 20 is integral for translations along the approach axis A to the tubular shaft 22 while the actuating rod 24 is sliding along the actuating axis B with respect to the gripper 20.

(59) The function of the tubular shaft 22 is to rotate and move the gripper 20 towards and away from the product to be wrapped. The purpose of the actuating rod 34 is to open and close the gripper 20.

(60) The gripper 20 comprises (see FIG. 5) a first jaw 70 and a second jaw 71. The first jaw 70 and the second jaw 71 are rotatably mounted about a respective clamping axis G on a gripper body 72. The gripper body 72 is constrained to the end 21 of the tubular shaft 22 and comprises a through opening through which the actuating rod 24 is slidingly inserted.

(61) The first jaw 70 comprises a first toothed wheel 73 hinged in the respective clamping axis G of the first jaw.

(62) The second jaw 71 comprises a second toothed wheel 74 hinged in the respective clamping axis G of the second jaw.

(63) The first toothed wheel 73 and the second toothed wheel 74 are permanently engaged on a rack 75 placed at one end of the actuating rod 24.

(64) The translation of the actuating rod 24 along the actuating axis B causes a translation of the rack 75 and a consequent rotation of the first toothed wheel 73 and the second toothed wheel 74 in opposite angular directions.

(65) The rotation in opposite angular directions of the first toothed wheel 73 and the second toothed wheel 74 results in respective rotations of the first jaw 70 and the second jaw 71 of the gripper 20.

(66) A translation of the actuating rod 24 towards the forward position corresponds to rotations of the first jaw 70 and second jaw 71 which close or tend to close the gripper 20.

(67) A translation of the actuating rod 24 towards the rearward position corresponds to rotations of the first jaw 70 and second jaw 71 which open or tend to open the gripper 20.

(68) In order to coordinate the movements of the first electric motor 30 and the second electric motor 31, the device 1 comprises a control unit 80 (diagrammed in FIG. 6).

(69) The control unit 80 is associated with a user interface 81 (also diagrammed in FIG. 6).

(70) The user interface 81 is configured to receive at least one input datum ID representing a desired operating parameter DOP of the gripper 20.

(71) Such a desired operating parameter SOP is a parameter which identifies a user-desired behaviour of the gripper 20 during its operation in a twist closing process of the end of the wrapper. Such a desired behaviour can be changed by the user by changing the input data ID according to specific usage requirements.

(72) By way of example, such a desired operating parameter DOP can be the translation distance which the tubular shaft 20 must travel during a translation along the approach axis A towards the forward position. In this case, the desired operating parameter SOP is related to the distance at which the gripper 20 is to be brought to the start of the operation to create the twist closure.

(73) A further example of such a desired operating parameter DOP can be the translation distance which the tubular shaft 20 must travel during a translation along the approach axis A to the rearward position. In this case, the desired operating parameter DOP is related to the distance at which the gripper 20 is to be brought at the end of the operation to create the twist closure.

(74) A further example of such a desired operating parameter DOP can be the point, along the approach axis A and during translation of the tubular shaft toward the forward position, at which a closing movement of the first jaw 70 and the second jaw 71 of the gripper 20 begins.

(75) Another example of such a desired operating parameter DOP can be the point, along the approach axis A and during the movement of the tubular shaft toward the rearward position, at which an opening movement of the first jaw 70 and the second jaw 71 of the gripper 20 begins.

(76) Further examples of such a desired operating parameter DOP could be the point, along the approach axis A, at which an opening movement of the first jaw 70 and the second jaw 71 ends or at which a closing movement of the first jaw 70 and the second jaw 71 ends.

(77) Further examples of such a desired operating parameter DOP can be the distance travelled by the tubular shaft 22 along the approach axis A during which the complete closing of the first jaw 70 and the second jaw 71 occurs, or during which the complete opening of the first jaw 70 and the second jaw 71 of the gripper 20 occurs.

(78) Other examples of such a desired operating parameter DOP could be the maximum rotation in opening of the first jaw 70 and the second jaw 71 or the maximum rotation in closing of the first jaw 70 and the second jaw 71 of the gripper 20.

(79) Another example of such a desired operating parameter DOP can be the clamping torque of the first jaw 70 and the second jaw 71 of the gripper 20.

(80) In the preferred embodiment of the invention, the user interface 81 is configured to receive a plurality of input data ID each representative of a desired operating parameter DOP of the gripper 20.

(81) The control unit 80 is configured at hardware, software and/or firmware level to obtain the desired operating parameters DOP from the input data ID and determine a gripper 20 law of motion from the derived desired operating parameters DOP. The control unit comprises, for example, a processor 85 configured for this purpose.

(82) Such a law of motion of the gripper 20 expresses, e.g., in respective position/time diagrams and/or in respective mathematical functions, the position of the gripper (or of a point representative of the position of the gripper 20) in time and the degree of opening and closing of first jaw 70 and second jaw 71 (or of points representative of the position of the first jaw 70 and second jaw 71) in time.

(83) In a preferred embodiment, the control unit 80 is configured to determine the law of motion of the gripper 20 by interpolating the desired operating parameters DOP with preset operating parameters POP.

(84) Such preset operating parameters POP are representative of positions which the gripper 20 must necessarily reach over time in order to obtain the desired behaviour.

(85) The desired operating parameters DOP can be expressed in terms of a plurality of points representing the desired position of the gripper 20 in time and the desired position of the first jaw 70 and the second jaw 71 in time.

(86) In turn, the preset operating parameters POP can be expressed in terms of a plurality of points representing the required position of the gripper 20 in time and the required position of the first jaw 70 and the second jaw 71 in time.

(87) By interpolating the above points (both those representative of the desired position and those of the required position), it is possible, for example, to determine the law of motion of the gripper 20.

(88) The control unit 80 is configured, once the law of motion of the gripper 20 has been determined, to break down such a law of motion into a first law of motion of the actuating rod 24 and a second law of motion of the tubular shaft 22.

(89) The first law of motion of the actuating rod 24 and the second law of motion of the tubular shaft 22 are determined by the control unit 80 so that the simultaneous actuation of the actuating rod 24 according to the first law of motion and the tubular shaft 22 according to the second law of motion results in the actuation of the gripper 20 according to its law of motion.

(90) The first law of motion expresses, e.g., in a position/time diagram and/or in a respective mathematical function, the position of the actuating rod 24 (or of a point representative of the position of the actuating rod 24) along the actuating axis B in time.

(91) The second law of motion expresses, e.g., in a position/time diagram and/or in a respective mathematical function, the position of the tubular shaft 22 (or of a point representative of the position of the tubular shaft 22) along the approach axis A in time.

(92) The control unit 80 is configured to generate a first control signal CS1 representing the first law of motion.

(93) In particular, the first control signal CS1 represents the position of the actuating rod 24 (or of a point representative of the position of the actuating rod 24) along the actuating axis B in time.

(94) The first control signal CS1 is sent to a driver 82 of the first electric motor 30 to actuate the first electric motor 30.

(95) The control unit 80 is also configured to generate a second control signal CS2 representing the second law of motion.

(96) In particular, the second control signal CS2 represents the position of the tubular shaft 22 (or a point representative of the position of the tubular shaft 22) along the approach axis A in time.

(97) The second control signal CS2 is sent to a driver 83 of the second electric motor 31 to actuate the second electric motor 31.

(98) The control unit 80 is also configured to generate a third control signal CS3 and send it to a driver 84 of the third electric motor 32.

(99) The third control signal CS3 is generated so as to rotate the tubular shaft during the entire twist winding process of the end of the wrapper.

(100) The third control signal CS3 can be calculated by the control unit 80 from a second input data ID2 entered in the user data entry interface 81. This second input data ID2 is representative of a desired rotation speed OP2 of the gripper 20 and the further gripper 20a when present.

(101) The desired rotation speed DOP2 can be constant or variable in time.

(102) In the event of twist winding both ends of the wrapper to obtain a double twist, the control unit 80 is configured to generate a further first control signal CS1a and an further control signal CS2a and send them to respective drivers 82a, 83a of the further first electric motor 30a and the further second electric motor 31a of the further winder 10a.

(103) Such a further first control signal CS1a and further control signal CS2a are generated from a further at least one input data IDa entered into the user data entry interface 81 and representative of a further desired operating parameter DOpa of the further gripper 20a as described above.

(104) In this case, said further desired operating parameter DOpa, in addition to the examples mentioned in connection with the operating parameter DOP, can also be the time lag between the start of the closing or opening of the further first jaw and further second jaw with respect to the opening or closing of the first jaw and second jaw.

(105) In some embodiments, the further operating parameter DOpa and the operating parameter DOP can also be variable as a function of the desired set rotation speed DOP2.