Method for changing wrapping material in wrapping devices

Abstract

A method for changing wrapping material in wrapping devices comprising the action a) of providing a winding apparatus comprising: a gripper (20) mechanically connected to an end (21) of a tubular shaft (22); an actuating rod (24), active on said gripper (20), slidable with respect to said tubular shaft (22) and rotatably constrained to said tubular shaft (22); a first electric motor (30) active on said actuating rod (24) to translate said actuating rod (24); a second electric motor (31 ) active on said tubular shaft (22) to translate said tubular shaft (22); a control unit (80) configured to drive the first electric motor (30) and the second electric motor (31). The method further comprises the action b) of supplying the control unit (80) with at least one input data (ID) representative of a desired operating parameter (DOR) of the gripper (20), wherein said control unit (80) is configured to determine a law of motion of the gripper (20) based on said at least one desired operating parameter (DOR). The method further comprises the action of c) operating the winding apparatus to wind a wrapping material on a product; d) verifying whether the obtained winding meets predetermined requirements. If the obtained winding does not meet these predetermined requirements, repeating actions b), c) and d). If the winding obtained meets said predetermined requirements, providing a control body (90) with cam paths (95, 96) which implement the law of motion determined by said control unit (80).

Description

[0001] METHOD FOR CHANGING WRAPPING MATERIAL IN WRAPPING DEVICES

[0002] DESCRIPTION

[0003] The present invention refers to a method for changing wrapping material in wrapping devices, wherein such wrapping provides for the twist or double twist closure of the wrapper.

[0004] The present invention is used in the manufacturing sector, for example in the food industry, to wrap products, preferably confectionery products such as chocolates, candies, sugared almonds and the like.

[0005] Twist or double twist product closures are obtained from usually rectangular sheets of wrappers at the centre of each of which a relative product to be wrapped is placed. The wrapper is then folded over the product so as to obtain a tubular shape of the wrapper. Next, (one end or) both ends of the wrapper are twisted to form (one or) two end twists.

[0006] In order to ensure repeatable windings of the wrappers and high production rates, automated wrapping devices have been developed that can twist one or both ends of the wrapper so as to achieve the above-described twist or double twist closure.

[0007] Such automated wrapping devices provide a wheel with horizontal rotation axis continuously moving on the circumferential surface of which are mounted handling equipment configured to retain products wound in a tubular wrapper. Two twisting devices act on opposite sides of the handling equipment to twist the ends of the tubular wrapper. Each twisting device comprises a gripping element which can be driven in opening and closing to grasp and release one end of the tubular wrapper. The gripping element is mounted at the end of a sleeve inside which a rack rod slides. The sliding of the rack rod in the sleeve determines the opening and closing of the gripping element. The sleeve slides along a sliding axis approaching and receding from the handling equipment and can be rotated about the sliding axis. The sliding of the rack rod inside the sleeve and the sliding of the sleeve along the sliding axis are carried out through a connection with cam followers inserted in cam paths usually obtained in a single control body (or in two distinct control bodies) set in rotation along a direction parallel to the sliding direction of the rack rod. The rotation of the sleeve determines the rotation of the gripping element. The sleeve slides toward and away from the handling equipment along with the rack rod to allow the gripping element to reach and move away from the end of the tubular wrapper, and the rack rod slides into the sleeve to open and close the gripping element. These two movements are coordinated with each other to allow the gripping element to grasp the wrapping material while the gripping element approaches the wrapping material, to retain the wrapping material while the sleeve is rotating, and to allow the gripping element to release the wrapping material while it moves away from the wrapping material.

[0008] The coordinated movement of the sleeve and of the rack rod is obtained from the shape of the cam paths which then define the law of motion of the gripping element.

[0009] An example of such wrapping devices is described in document US4539790A.

[0010] The Applicant has noted that in the field of product wrappings the wrapping materials are subject to constant research to make such wrapping materials increasingly compatible with the environment and increasingly performing in terms for example of preservation of the properties of the wrapped product.

[0011] The Applicant has noted that, in order to obtain the same type of twist closure with wrapping materials of different types, different degrees of closure of the gripping element (i.e. reciprocal approaches between the gripping element parts), or, in combination, different instants of opening and closing of the gripping element may be required.

[0012] The Applicant has in fact noted that the law of motion of the gripping element adapted to obtain a certain twist closure with a certain wrapping material is not always, and indeed almost never, able to realize the same twist closure with a wrapping material of different type.

[0013] The Applicant has therefore verified that in order to proceed with a change of wrapping material in the wrapping devices it is necessary to change the law of motion of the gripping element.

[0014] The Applicant has noted that being a law of motion that must follow the gripping elements known, it is possible, and it is known to a person skilled in art, to configure the control body with cam paths that allow the gripping element to follow exactly that law of motion. The Applicant has however noted that following the change of type of the wrapping material, the new law of motion is not known a priori and can only be determined with a heuristic “trial and error” method that aims to find the correct law of motion by making several attempts and by verifying the effect obtained on the wrapping material until a satisfactory result is reached.

[0015] The Applicant has verified that in order to implement said heuristic method it is necessary to provide, at each attempt, a control body having cam paths that implement a test law of motion and mount this control body in the device.

[0016] However, the Applicant has noted that such a process would require very high times and costs that are necessary to design, produce and implement a number (not determinable a priori) of control bodies until the control body that has cam paths implementing the correct law of motion of the gripping element is identified.

[0017] The Applicant has noted that this inconvenience can occur not only in devices for wrapping twist wrappers but also in wrapping devices that provide other types of wrapper and that envisage using control bodies with cam paths whenever it is necessary to change the type of wrapper to be used.

[0018] The Applicant has realized that in these situations it could be advantageous to be able to simulate the behaviour of the wrapping device, and in particular of the control body with cam paths, in such a way as to be able to simulate different operations of the wrapping device when the cam paths are varied.

[0019] The Applicant has however noted that although it is possible to produce a numerical simulation (i.e. a simulation using computer-implemented mathematical models) of the wrapping device, a mathematical model simulating the behaviour of the new wrapping material is never or almost never available. Therefore, in the Applicant's experience it is not possible to numerically simulate with adequate precision the behaviour of the wrapping device when used with different types of wrapping material.

[0020] The Applicant has perceived that, since the behaviour of various types of wrapping material cannot be numerically simulated, any simulation of the behaviour of the wrapping device on different wrapping materials must be carried out without being able to simulate the wrapping material, i.e. it must be carried out using physically the wrapping material.

[0021] The Applicant has therefore perceived that a physical model of the wrapping device could be realized in which the operation of the control body with cam paths is simulated by one or more members that can be reconfigured with negligible time and costs, so as to be able to carry out heuristic “trial and error” tests by reconfiguring said members until the desired wrapper with the new or particular wrapping material is obtained.

[0022] The Applicant has therefore found that by providing a physical model of the wrapping device in which the control body with cam paths is replaced by one or more electric motors which, through appropriate kinematic mechanisms, actuate the bending member of the wrapping device (for example the gripper) exactly as said bending member is actuated by the control body with cam paths, it would be possible to carry out heuristic “trial and error” tests by varying the driving of the electric motors until the desired wrapping with the new or particular wrapping material is obtained.

[0023] The Applicant has also found that by determining the law of motion followed by the bending member of the physical model of the wrapping device, it is possible to provide cam paths on a control body that, when mounted in the wrapping device, allow the wrapping device to provide the desired wrapping with the new or particular wrapping material.

[0024] The present invention therefore concerns, in a first aspect thereof, a method for changing the wrapping material in a wrapping device.

[0025] Preferably, it is envisaged providing a model of a wrapping device with a cam path control body and provided with a manipulator member configured to contact a wrapping material and perform operations on such wrapping material, wherein in said model of a wrapping device the cam path control body is replaced by an electric motor, wherein the number of electric motors is correlated to the number of cam paths, wherein the model of wrapping device comprises active kinematic mechanisms between said electric motors and said manipulator member, and wherein the model of wrapping device comprises a control unit configured to drive said electric motors.

[0026] Preferably, said winding apparatus comprises a control unit configured to drive the first electric motor and the second electric motor.

[0027] Preferably, it is envisaged supplying the control unit with at least one input data representative of a desired operating parameter of the manipulator member, wherein said control unit is configured to determine a law of motion of the manipulator member based on said at least one desired operating parameter.

[0028] Preferably, it is envisaged operating the wrapping device model to obtain a wrapping material on a product.

[0029] Preferably, it is envisaged verifying whether the obtained wrapper meets predetermined requirements.

[0030] Preferably, if the obtained wrapper does not meet said predetermined requirements, it is envisaged repeating the actions of supplying the control unit with at least one input data representative of a desired operating parameter of the manipulator member, wherein said control unit is configured to determine a law of motion of the manipulator member based on said at least one desired operating parameter; operating the wrapping device model to obtain a wrapping material on a product; verifying whether the obtained wrapper meets predetermined requirements.

[0031] Preferably, if the obtained wrapper meets said predetermined requirements, it is envisaged providing a control body with cam paths that implement the law of motion determined by said control unit.

[0032] The present invention concerns, in a second aspect thereof, a method for changing wrapping material in wrapping devices.

[0033] Preferably, it is envisaged providing a winding apparatus comprising a gripper.

[0034] Preferably, said gripper is mechanically connected to one end of a tubular shaft, wherein said gripper is rotatable and translatable integrally with said tubular shaft.

[0035] Preferably said winding apparatus comprises an actuating rod, active on said gripper, slidable with respect to said tubular shaft and rotationally constrained to said tubular shaft, wherein said gripper is openable and closable as a result of a translation of the actuating rod.

[0036] Preferably, said winding apparatus comprises a first electric motor active on said actuating rod to translate said actuating rod.

[0037] Preferably, said winding apparatus comprises a second electric motor active on said tubular shaft to translate said tubular shaft.

[0038] Preferably, said winding apparatus comprises a control unit configured to drive the first electric motor and the second electric motor.

[0039] Preferably, it is envisaged supplying the control unit with at least one input data representative of a desired operating parameter of the gripper, wherein said control unit is configured to determine a law of motion of the gripper based on said at least one desired operating parameter.

[0040] Preferably, it is envisaged operating the winding apparatus to obtain a wrapping material on a product.

[0041] Preferably, it is envisaged verifying whether the obtained winding meets predetermined requirements.

[0042] Preferably, if the obtained winding does not meet said predetermined requirements, it is envisaged repeating the actions of supplying the control unit with at least one input data representative of a desired operating parameter of the gripper, wherein said control unit is configured to determine a law of motion of the gripper based on said at least one desired operating parameter; operating the winding apparatus model to obtain a wrapping material on a product; verifying whether the obtained wrapper meets predetermined requirements.

[0043] Preferably, if the obtained winding meets said predetermined requirements, it is envisaged providing a control body with cam paths that implement the law of motion determined by said control unit.

[0044] The Applicant has perceived that by providing a winding apparatus with two electric motors that operate, respectively, the actuating rod and the tubular shaft, it is possible to change the law of motion of the gripper by operating one or both of the electric motors differently.

[0045] The Applicant has perceived that by providing the winding apparatus with a command and control unit configured to determine a law of motion of the gripper based on at least one desired operating parameter, it is possible to carry out heuristic “trial and error” tests by varying such at least one operating parameter as long as the gripper follows a law of motion that allows the correct winding of the new or particular sheet of wrapper.

[0046] The Applicant has found that in this way the variation of the law of motion of the gripper can be implemented in real time without having to intervene on the device to change physical components of the same. The Applicant has found that by determining in this way the law of motion to be followed by the gripper, it is possible to configure the cam paths of a control body in such a way as to reproduce this law of motion. By replacing the control body of a wrapping device with the control body thus configured, it is therefore possible to proceed with a change of wrapping material with very short times and costs.

[0047] In the present description and subsequent claims, the term “law of motion” refers to one or more relations which describe the motion of a physical system. The physical system referred to in the present description and subsequent claims is the gripper (when reference is made to a law of motion of the gripper) or the tubular shaft (when reference is made to the law of motion of the tubular shaft) or the actuating rod (when reference is made to the law of motion of the actuating rod). For example, the law of motion can be represented by a mathematical function or diagram describing the position of an object (i.e. , of the gripper or its components, of the actuating rod or of the tubular shaft) as a function of time, alternatively or in combination it can be represented by a mathematical function or diagram describing the speed of an object (i.e., of the gripper or its components, of the actuating rod or of the tubular shaft) as a function of time, alternatively or in combination can be represented by a mathematical function or diagram describing the acceleration of an object (i.e., the gripper or its components, of the actuating rod or of the tubular shaft) as a function of time.

[0048] The present invention may have, in one or both aspects thereof, at least one of the preferred features described below. Such features may be present singly or in combination with each other, unless expressly stated otherwise, in the method for changing wrapping material in wrapping devices of the present invention.

[0049] The manipulator member according to the first aspect of the present invention may be the gripper according to the second aspect of the present invention.

[0050] The wrapping device model according to the first aspect of the present invention may be the winding apparatus according to the second aspect of the present invention.

[0051] Preferably, said kinematic mechanisms according to the first aspect of the present invention comprise the components according to the second aspect of the present invention interposed between the gripper, the first electric motor and the second electric motor.

[0052] Preferably, the gripper comprises a first jaw and a second jaw. Preferably, said tubular shaft is rotatable about said approach axis and translatable along said approach axis.

[0053] Preferably, said actuating rod is slidable along an actuating axis parallel to, or coincident with, said approach axis.

[0054] Preferably, said actuating rod is slidable along said actuating axis with respect to said tubular shaft.

[0055] Preferably, said gripper is openable and closable as a result of a translation of the actuating rod along the actuating axis.

[0056] Preferably, the desired operating parameter of the gripper is a parameter describing a position or state of a component of the gripper or a component connected to the gripper.

[0057] Preferably, the desired operating parameter is a parameter indicative of operation of the gripper during a wrapping operation.

[0058] Preferably, said desired operating parameter of the gripper is selected from at least one of the following parameters: translation of the tubular shaft along a first direction; translation of the tubular shaft in a second direction; point at which a closing movement of the gripper begins; point at which a closing movement of the gripper ends; point at which an opening movement of the gripper begins; point at which an opening movement of the gripper ends; stroke of the tubular shaft during which a complete closing movement of the gripper takes place; stroke of the tubular shaft during which a complete opening movement of the gripper takes place; tightening torque of the gripper.

[0059] Preferably, said desired operating parameter of the gripper is selected from at least one of the following parameters: translation of the tubular shaft along the approach axis in a first direction; translation of the tubular shaft along the approach axis in a second direction; point, along the approach axis, at which a closing movement of the first jaw and of the second jaw of the gripper begins; point, along the approach axis, at which a closing movement of the first jaw and of the second jaw of the gripper ends; point, along the approach axis, at which an opening movement of the first jaw and of the second jaw of the gripper begins; point, along the approach axis, at which an opening movement of the first jaw and the second jaw of the gripper ends; stroke of the tubular shaft along the approach axis during which a complete closure of the first jaw and of the second jaw of the gripper takes place; stroke of the tubular shaft along the approach axis during which the complete opening of the first jaw and of second jaw of the gripper takes place; maximum opening rotation of the first jaw and of the second jaw of the gripper; maximum closing rotation of the first jaw and of second jaw of the gripper; tightening torque of the first jaw and of the second jaw of the gripper.

[0060] Preferably, said desired operating parameter of the gripper is selected by a user on the basis of the user's experience and knowledge of the wrapping material used and on the expected behaviour, based on that experience, of said wrapping material.

[0061] Preferably, said law of motion of the gripper is a mathematical function describing the position of at least one point representative of the gripper as a function of time.

[0062] Alternatively or in combination, said law of motion of the gripper is preferably a mathematical function describing the position of one or more points representative of the first and second jaws of the gripper as a function of time.

[0063] Preferably, said control unit is configured to interpolate said at least one desired operating parameter with preset operating parameters to determine said law of motion of the gripper based on the result of said interpolation.

[0064] Preferably, such preset operating parameters are predetermined and set in the control unit by the manufacturer, e.g., stored in a memory of the control unit as system parameters. Preferably, said preset operating parameters are representative of positions which the gripper must necessarily reach over time in order to be able to obtain the desired behaviour.

[0065] Preferably, said at least one desired operating parameter can be represented with a plurality of points representative of the desired position of the gripper over time.

[0066] Preferably, said preset operating parameters can be represented with a plurality of points representative of the required position of the gripper over time.

[0067] Preferably, said law of motion is obtained by interpolating said plurality of points representative of the required position of the gripper over time and said plurality of points representative of the desired position of the gripper over time.

[0068] Preferably, said control unit is also configured to determine, based on 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.

[0069] Preferably, the first law of motion of the actuating rod is a mathematical function describing the position of at least one point representative of the actuating rod as a function of time.

[0070] More preferably, the first law of motion of the actuating rod is a mathematical function describing the position of at least one point representative of the actuating rod along the actuating axis as a function of time.

[0071] Preferably, the second law of motion of the tubular shaft is a mathematical function describing the position of at least one point representative of the tubular shaft as a function of time.

[0072] More preferably, said second law of motion of the tubular shaft is a mathematical function describing the position of at least one point representative of the tubular shaft along the approach axis as a function of time.

[0073] Preferably, providing a control body with cam paths that implement the law of motion determined by said control unit comprises receiving from the control unit a mathematical function or a diagram describing the position of the gripper as a function of time and using said mathematical function or diagram to determine said cam paths.

[0074] Alternatively or in combination with receiving from the control unit a mathematical function or a diagram describing the position of the gripper as a function of time, it is envisaged receiving from the control unit a mathematical function or a diagram describing the acceleration of the gripper as a function of time.

[0075] Preferably, receiving from the control unit a mathematical function or a diagram describing the position of the gripper as a function of time comprises receiving from the control unit a mathematical function or a diagram describing the position of the actuating rod as a function of time and a mathematical function or a diagram describing the position of the tubular shaft as a function of time.

[0076] Alternatively or in combination with receiving from the control unit a mathematical function or a diagram describing the position of the actuating rod as a function of time and a mathematical function or a diagram describing the position of the tubular shaft as a function of time, it is envisaged receiving from the control unit a mathematical function or a diagram describing the acceleration of the actuating rod as a function of time and a mathematical function or a diagram describing the acceleration of the tubular shaft as a function of time.

[0077] Preferably, providing a control body with cam paths implementing the law of motion determined by said control unit comprises providing a single actuator with a first cam path implementing the first law of motion and with second cam path implementing the second law of motion.

[0078] Preferably, said single actuator comprises an outer surface on which said first cam path and said second cam path are obtained.

[0079] Alternatively, providing a control body with cam paths implementing the law of motion determined by said control unit comprises providing a first actuator with a first cam path implementing the first law of motion and providing a second actuator with a second cam path implementing the second law of motion.

[0080] Preferably, said first actuator comprises an outer surface on which said first cam path is obtained.

[0081] Preferably, said second actuator comprises an outer surface on which said second cam path is obtained.

[0082] Preferably, each cam path is a groove obtained on the outer surface of the single actuator or of the first and second actuators.

[0083] Preferably, each groove provides a closed path along the outer surface of the single actuator or of the first and second actuators.

[0084] Preferably, after providing a control body with cam paths that implement the law of motion determined by said control unit it is envisaged mounting said control body in a wrapping device comprising: a gripper mechanically connected to one end of a tubular shaft, wherein said gripper is rotatable and translatable integrally with said tubular shaft; an actuating rod, active on said gripper, slidable with respect to said tubular shaft and rotationally constrained to said tubular shaft, wherein said gripper is openable and closable as a result of a translation of the actuating rod; wherein said control body is kinematically connected, through a cam follower slidable in a first cam path of said cam paths, to said actuating rod to translate said actuating rod and wherein said control body is further kinematically connected, through a cam follower slidable in a second cam path of said cam paths, to said tubular shaft to translate said tubular shaft.

[0085] Preferably, said control unit of the winding apparatus is configured to generate a first control signal and send it to a driver of the first electric motor.

[0086] Preferably, said first control signal is representative of the first law of motion of the tubular shaft.

[0087] Preferably, said control unit is configured to generate said first control signal representative of the first law of motion and send it to said driver of the first electric motor.

[0088] Preferably, said control unit is configured to generate a second control signal and send it to a driver of the second electric motor.

[0089] Preferably, said second control signal is representative of the second law of motion of the tubular shaft.

[0090] Preferably, said control unit is configured to generate said second control signal representative of the second law of motion and send it to said driver of the second electric motor.

[0091] Preferably, the first control signal and the second control signal are generated so that the translation of the actuating rod and the translation of the tubular shaft are coordinated to achieve a predetermined movement of the gripper.

[0092] Preferably, there is provided a third electric motor active on said tubular shaft to rotate said tubular shaft preferably about the approach axis.

[0093] Preferably, said control unit is configured to drive the third electric motor.

[0094] Preferably, said control unit is configured to generate a third control signal and send it to a driver of the third electric motor.

[0095] Preferably, said third control signal is representative of the rotation speed of the tubular shaft.

[0096] Preferably, the rotation speed of the gripper coincides with the rotation speed of the tubular shaft.

[0097] Preferably, the third control signal is generated so as to coordinate the translation of the actuating rod and the translation of the tubular shaft with the rotation of the tubular shaft to achieve a predetermined movement and rotation of the gripper.

[0098] Preferably, the winding apparatus comprises a data input user interface configured to receive at least one input data representative of said desired operating parameter of the gripper.

[0099] Preferably, said data input user interface is further configured to receive at least one additional input data representative of a rotational speed of the gripper.

[0100] Preferably, supplying the control unit with at least one input data representative of a desired operating parameter of the gripper comprises providing the control unit with a plurality of input data each representative of a desired operating parameter of the gripper.

[0101] Preferably, there is provided a transmission shaft which is connected to said third electric motor.

[0102] Preferably, operating the third electric motor causes the transmission shaft to rotate about a transmission axis.

[0103] Preferably, the transmission axis is parallel to the approach axis.

[0104] Preferably, a pinion is keyed to said transmission shaft to rotate with said transmission shaft.

[0105] Preferably, the first jaw and the second jaw are respectively provided with a first toothed wheel and a second toothed wheel.

[0106] Preferably, the first toothed wheel and the second toothed wheel are rotatable, together with the relative first and second jaw, about a tightening axis perpendicular to the actuating axis.

[0107] Preferably, the actuating rod comprises a rack geared with the first toothed wheel and the second toothed wheel.

[0108] Preferably, a translation in a first direction of the actuating rod along the actuating axis causes a rotation of the first toothed wheel in a first angular direction and a rotation of the second toothed wheel in a second angular direction.

[0109] Preferably, a rotation of the first toothed wheel in a first angular direction and a rotation of the second toothed wheel in a second angular direction causes the first jaw and the second jaw of the gripper to close. Preferably, a translation in a second direction, opposite the first direction, of the actuating rod along the actuating axis causes a rotation of the first toothed wheel in a second angular direction and a rotation of the second toothed wheel in a first angular direction.

[0110] Preferably, a rotation of the first toothed wheel in a second angular direction and a rotation of the second toothed wheel in a first angular direction causes the opening of the first jaw and the second jaw of the gripper.

[0111] Preferably, said winding apparatus comprises a first fork.

[0112] Preferably, said first fork is driven directly or indirectly by the first electric motor to translate said actuating rod along the actuating axis.

[0113] Preferably, said actuating rod is rotatable about said actuating axis with respect to said first fork.

[0114] Preferably, said winding apparatus comprises a second fork.

[0115] Preferably, said second fork is driven directly or indirectly by the second electric motor to translate said tubular shaft along the approach axis.

[0116] Preferably, said tubular shaft is rotatable about said approach axis with respect to said second fork.

[0117] Preferably, there is provided an additional winding apparatus.

[0118] Preferably, the additional winding apparatus is used in combination with said winding apparatus to make a double twist wrapper, wherein a twist winding is made at each of the opposite ends of the wrapper.

[0119] Preferably, the additional winding apparatus is identical in structure and operation to said winding apparatus.

[0120] 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 nonlimiting example, in which:

[0121] Figure 1 is a schematic perspective view of a winding apparatus usable in the method for changing wrapping material in wrapping devices in accordance with the present invention in an open condition; Figure 2 is a schematic perspective view of a detail of the winding apparatus of Figure 1 ;

[0122] Figure 3 is a schematic perspective view of some parts of the detail of the winding apparatus of Figure 2;

[0123] Figure 4 is a schematic perspective view of further parts of the detail of the winding apparatus of Figure 2;

[0124] Figure 5 represents a schematic sectional view according to the plane V-V of a detail of the winding apparatus of Figure 1 ;

[0125] Figure 6 is a block diagram representative of some components of the winding apparatus; and

[0126] Figures 7 and 8 are schematic representations of a control body with cam paths.

[0127] In the attached figures, a winding apparatus usable in the method for changing wrapping material in wrapping devices in accordance with the present invention is generally indicated by the reference numeral 10.

[0128] A winding apparatus 10 is represented on the left in Figure 1 and an additional winding apparatus 11 is represented on the right in Figure 1 .

[0129] Between the winding apparatus 10 and the additional winding apparatus 11 there is arranged a feeder of products to be wrapped 12 (represented only schematically) rotatable about an axis of rotation X. The feeder of products to be wrapped 12 comprises a plurality of seats (not illustrated) in each of which there is arranged a corresponding wrapper partly wrapped by a wrapping material identical to the wrapping material to be replaced in a wrapping device. Such wrapping 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 12 sequentially places the products partially wrapped by the wrapping material between the winding apparatus 10 and the further winding apparatus 11 .

[0130] The winding apparatus 10 and the further winding apparatus 11 are configured to make a corresponding twist on the wrapping material that wraps the product.

[0131] The winding apparatus 10 and the further winding apparatus 11 are arranged facing each other with the product feeder 12 arranged therebetween. The winding apparatus 10 and the further winding apparatus 11 are structurally identical to each other, unless explicitly described hereinafter, and are arranged symmetrically with respect to an ideal plane perpendicular to the axis of rotation X of the product feeder 12.

[0132] Therefore, what is described in relation to the winding apparatus 10 identically applies for the further winding apparatus 11. The components of the winding apparatus 10 are also present in the further winding apparatus 11 and are represented in Figure 1 , where necessary, with corresponding reference numerals followed by the letter “a”.

[0133] The further winding apparatus 11 may not be provided, just as the product feeder 12 may not be provided which may also be replaced by a static feeder (not illustrated) which retains the product, with the wrapping material wrapped thereon, in front of the winding apparatus 10.

[0134] The winding apparatus 10 comprises a gripper 20 mounted to 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.

[0135] Figure 1 shows the further gripper 20a, the further tubular shaft 22a, the end 21 a of the further tubular shaft 22a and the further containment body 23a of the further winding apparatus 11.

[0136] As better represented in Figure 3, the tubular shaft 22 is rotatably mounted inside the containment body 23 (not illustrated in Figure 3) to rotate about an approach axis A.

[0137] An actuating rod 24, which is rotationally integral with the tubular shaft 22 through, for example, a pin or shape coupling, is inserted inside the tubular shaft 22.

[0138] The actuating rod 24 also rotates about the approach axis A.

[0139] 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 moved away from the feeder of products 12 to be wrapped and in the forward position the end 21 of the tubular shaft 22 is approached by the feeder of products 12 to be wrapped.

[0140] The actuating rod 24 is slidable along an actuating axis B coincident with the approach axis A. The actuating rod 24 is slidable inside the tubular shaft 22 and with respect to the tubular shaft 22. The actuating rod 24 is slidable along the actuating axis B between a rearward position 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.

[0141] 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.

[0142] A second electric motor 31 is provided to drive the translation of the tubular shaft 22 along the approach axis A.

[0143] A third electric motor 32 is provided to drive the rotation of the tubular shaft 22 and the actuating rod 24 therewith.

[0144] As shown in Figure 2, the third electric motor is connected to a transmission shaft 40 having a rotation axis C parallel to and spaced from the approach axis A.

[0145] 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 through an input shaft to the drive shaft of the third electric motor 32 and through an output shaft to the transmission shaft 40. The function of the speed reducer 40 is to rotate the drive shaft 40 at a different speed (preferably lower) than the rotation speed of the drive shaft of the third electric motor 32.

[0146] A pinion 41 is keyed to the drive shaft 40, which rotates integrally with the drive 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.

[0147] The toothed roller 42 is also geared with a gear 43 keyed to the tubular shaft 22.

[0148] The rotation of the transmission shaft 40 causes a rotation of the tubular shaft 22.

[0149] Both the pinion 41 , the toothed roller 42 and the gear 43 have straight teeth, so that the gear 43 can translate along the approach axis A (together with the tubular shaft 22) without losing the 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.

[0150] The third electric motor 32 further drives the rotation of the further tubular shaft 22a and the further actuating rod of the further winding apparatus 11 (when present).

[0151] In this regard, as shown in Figure 1 , the transmission shaft 40 extends between the winding apparatus 10 and the further winding apparatus 11 until it reaches the further winding apparatus 11. At the further winding apparatus 11 , 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.

[0152] As described above, a first electric motor 30 is provided to drive the translation of the actuating rod 24 along the actuating axis B.

[0153] 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.

[0154] 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.

[0155] 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 tubular shaft 22 and placed on opposite sides with respect to the through opening.

[0156] 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.

[0157] In a first embodiment illustrated in the accompanying figures, the first electric motor 30 drives the first fork 50 via a first control rod 53. In this embodiment, the first electric motor 30 comprises a rotating drive motor. The first electric motor 30 generates a mechanical torque on the rotating drive motor, rotating the latter.

[0158] The first control rod 53 comprises a first end 54 rotatably connected to the first fork 50 around a hinge axis perpendicular to the actuating axis B.

[0159] 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.

[0160] 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 into translation the actuating rod 24 towards the forward position.

[0161] 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 into translation the actuating rod 24 towards the rearward position.

[0162] 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 motor. The second electric motor 31 generates a mechanical torque on the rotating drive motor, rotating the latter.

[0163] The second control rod 57 comprises a first end 58 rotatably connected to the second fork 51 about a hinge axis perpendicular to the approach axis A.

[0164] The second control rod 57 comprises a second end 59 opposite the first end 58 stably 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 rotate the second control rod 57 at a different speed (preferably lower) than the rotation speed of the drive shaft of the second electric motor 31 .

[0165] 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 into translation the tubular shaft 22 towards the forward position.

[0166] 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 into translation the tubular shaft 22 towards the rearward position.

[0167] 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 drive shaft which sets the drive shaft in motion along a straight trajectory, either in a first direction or in a second direction opposite to the first.

[0168] The translation direction of the drive shaft is parallel and preferably coincident with the actuating axis B.

[0169] The drive shaft is connected, either directly or via a return, to the first fork 50.

[0170] 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 into translation the actuating rod 24 towards the forward position.

[0171] 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 into translation the actuating rod 24 towards the rearward position.

[0172] 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 drive shaft which sets the drive shaft in motion along a straight trajectory, either in a first direction or in a second direction opposite to the first.

[0173] The translation direction of the drive shaft is parallel and preferably coincident with the approach axis A.

[0174] The drive shaft is connected, either directly or via a return, to the second fork 51 .

[0175] 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 into translation the tubular shaft 22 towards the forward position.

[0176] 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 into translation the tubular shaft 22 towards the rearward position.

[0177] 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.

[0178] 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.

[0179] The gripper 20 comprises (see Figure 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 tightening 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.

[0180] The first jaw 70 comprises a first toothed wheel 73 hinged in the respective tightening axis G of the first jaw.

[0181] The second jaw 71 comprises a second toothed wheel 74 hinged in the respective tightening axis G of the second jaw. The first toothed wheel 73 and the second toothed wheel 74 are permanently geared on a rack 75 placed at one end of the actuating rod 24.

[0182] 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.

[0183] The rotation in opposite angular directions of the first toothed wheel 73 and the second toothed wheel 74 causes respective rotations of the first jaw 70 and the second jaw 71 of the gripper 20.

[0184] A translation of the actuating rod 24 towards the forward position corresponds to rotations of the first jaw 70 and of the second jaw 71 which close or tend to close the gripper 20.

[0185] A translation of the actuating rod 24 towards the rearward position corresponds to rotations of the first jaw 70 and of the second jaw 71 which open or tend to open the gripper 20.

[0186] To coordinate the movements of the first electric motor 30 and of the second electric motor 31 , the apparatus 10 comprises a control unit 80 (schematized in Figure 6).

[0187] The control unit 80 is associated with a user interface 81 (also schematized in Figure 6).

[0188] The user interface 81 is configured to receive at least one input data ID representative of a desired operating parameter DOP of the gripper 20.

[0189] Such a desired operating parameter DOP 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.

[0190] In other words, such a desired operating parameter DOP is a parameter that identifies a desired behaviour of the gripper 20 on the wrapping material during the twist closing process of the end of the wrapper.

[0191] Such desired behaviour of the gripper 20 can be changed by the user by changing the input data ID.

[0192] By way of example, said desired operating parameter DOP may be the point, along the approach axis A and during the translation of the tubular shaft towards the forward position, in which a closing movement of the first jaw 70 and of the second jaw 71 of the gripper 20 begins. In this example, the operator wants, in a “trial and error” process, to evaluate how the product is wrapped with a specific wrapping material when the chosen point is set, along the approach axis A and during the translation of the tubular shaft towards the forward position, in which a closing movement of the first jaw 70 and of the second jaw 71 of the gripper 20 begins.

[0193] 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 DOP is correlated to the distance at which the gripper 20 is to be brought at the start of the operation to create the twist closure.

[0194] 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 towards the rearward position. In this case, the desired operating parameter DOP is correlated to the distance at which the gripper 20 is to be brought at the end of the operation to create the twist closure.

[0195] A further example of such a desired operating parameter DOP can be the point, along the approach axis A and during the translation of the tubular shaft toward the forward position, at which a closing movement of the first jaw 70 and of the second jaw 71 of the gripper 20 begins.

[0196] Another example of such a desired operating parameter DOP can be the point, along the approach axis A and during the translation of the tubular shaft toward the rearward position, at which an opening movement of the first jaw 70 and of the second jaw 71 of the gripper 20 begins.

[0197] 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 of the second jaw 71 ends or at which a closing movement of the first jaw 70 and of the second jaw 71 ends.

[0198] 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 of the second jaw 71 occurs, or during which the complete opening of the first jaw 70 and of the second jaw 71 of the gripper 20 occurs.

[0199] Other examples of such a desired operating parameter DOP could be the maximum rotation in opening of the first jaw 70 and of the second jaw 71 or the maximum rotation in closing of the first jaw 70 and of the second jaw 71 of the gripper 20.

[0200] Another example of such a desired operating parameter DOP can be the tightening torque of the first jaw 70 and of the second jaw 71 of the gripper 20.

[0201] 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.

[0202] 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 law of motion of the gripper 20 based on the derived desired operating parameters DOP. The control unit comprises, for example, a processor 85 configured for this purpose.

[0203] 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 20 (or of a point representative of the position of the gripper 20) over time and the degree of opening and closing of first jaw 70 and of the second jaw 71 (or of points representative of the position of the first jaw 70 and second jaw 71 ) over time.

[0204] 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.

[0205] 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.

[0206] The desired operating parameters DOP can be expressed in terms of a plurality of points representative of the desired position of the gripper 20 over time and of the desired position of the first jaw 70 and the second jaw 71 over time.

[0207] In turn, the preset operating parameters POP can be expressed in terms of a plurality of points representative of the required position of the gripper 20 over time and of the required position of the first jaw 70 and of the second jaw 71 over time.

[0208] 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.

[0209] 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.

[0210] 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 of the tubular shaft 22 according to the second law of motion causes the actuation of the gripper 20 according to its law of motion.

[0211] 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 over time.

[0212] 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 over time.

[0213] The control unit 80 is configured to generate a first control signal CS1 representing the first law of motion.

[0214] 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 over time.

[0215] The first control signal CS1 is sent to a driver 82 of the first electric motor 30 to actuate the first electric motor 30.

[0216] The control unit 80 is also configured to generate a second control signal CS2 representing the second law of motion.

[0217] The second control signal CS2 represents, in particular, 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 over time.

[0218] The second control signal CS2 is sent to a driver 83 of the second electric motor 31 to actuate the second electric motor 31 .

[0219] 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.

[0220] The third control signal CS3 is generated so as to rotate the tubular shaft during the entire twist wrapping process of the end of the wrapper.

[0221] The third control signal CS3 can be calculated by the control unit 80 based on 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.

[0222] The desired rotation speed DOP2 can be constant or variable over time.

[0223] In case of twist wrapping of both ends of the wrapper to obtain a double twist, the control unit 80 is configured to generate a further first control signal CS1 a and a further control signal CS2a and send them to respective drivers 82a, 83a of the further first electric motor 30a and of the further second electric motor 31 a of the further winding apparatus 11 .

[0224] Such a further first control signal CS1 a and further control signal CS2a are generated based on an additional 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.

[0225] In this case, said further desired operating parameter DOpa, in addition to the examples mentioned in relation to the operating parameter DOP, can also be the time shift between the start of the closing or of the opening of the further first jaw and further second jaw with respect to the opening or closing of the first jaw and second jaw.

[0226] 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.

[0227] In accordance with the method for changing wrapping material in wrapping devices of the present invention, the winding apparatus 10 (and possibly the further winding apparatus 11 ) are operated with the wrapping material to be used in a wrapping device having a control body or control bodies provided with cam paths.

[0228] The control unit 80 is provided with one or more input data ID representative of as many desired operating parameters DOP that the user, on the basis of his experience in the field, considers to be suitable in order to move the gripper 20 so as to obtain the desired wrapping of used wrapping material.

[0229] The control unit 80 determines the law of motion of the gripper 20 based on the received one or more desired operating parameters DOP.

[0230] The winding apparatus 10 performs folding operations of the wrapping material according to the above-described manners.

[0231] At the end of the operation, the user (or a computerized inspection system) verifies whether the obtained winding meets the required requirements.

[0232] If this does not happen, i.e. if the winding of the wrapping material is not satisfactory, the control unit 80 is provided with further input data ID (at least partially different from those previously provided) representative of as many desired operating parameters DOP that the user, on the basis of the previously obtained result and his experience in the field, considers to be better suitable in order to move the gripper 20 so as to obtain the desired winding of used wrapping material.

[0233] The control unit 80 determines a new law of motion of the gripper 20.

[0234] The winding apparatus 10 performs again the folding operations of the wrapping material according to the further described manners.

[0235] At the end of the operation, the user (or a computerized inspection system) verifies whether the obtained winding meets the required requirements.

[0236] This process is repeated until the obtained winding meets the required requirements.

[0237] At this point, being the law of motion that allowed the gripper 20 to obtain the desired winding known, a control body 90 with cam paths that implement the found law of motion is provided. The determination of the cam paths is in itself a process known to the person skilled in the art once the law of motion of the gripper 20 is known.

[0238] The law of motion may be provided by the control unit 80 as the representation of a mathematical function or a diagram describing the position of the gripper 20 as a function of time.

[0239] Alternatively or in combination the law of motion may be provided by the control unit 80 as the representation of a mathematical function or a diagram describing the acceleration of the gripper 20 as a function of time.

[0240] In the preferred embodiment of the invention, the law of motion is provided by the control unit 80 broken down into the first law of motion of the actuating rod 24 and into the second law of motion of the tubular shaft 22.

[0241] This solution is particularly preferred when the control body 90 has a first cam path implementing the first law of motion and a second cam path implementing the second law of motion.

[0242] The control body 90 may be a single actuator 91 or may be provided by two actuators 92, 93.

[0243] In Figure 7 a control body 90 provided by a single actuator 91 is schematically represented. Said single actuator 91 comprises a substantially cylindrical outer surface 94 on which a first cam path 95 and a second cam path 96 are obtained (which have been represented in planar development for illustrative clarity). The first cam path 95 and the second cam path 96 are obtained from as many grooves obtained on the substantially cylindrical outer surface 94.

[0244] Figure 8 schematically shows a control body 90 provided by two actuators 92, 93. Each actuator 92, 93 comprises a respective substantially cylindrical outer surface 97, 98 on which the first cam path 95 and the second cam path 96 are respectively obtained (which have been represented in planar development for illustrative clarity). The first cam path 95 and the second cam path 96 are obtained from as many grooves obtained on the substantially cylindrical outer surface 97, 98 of the respective actuator 92, 93.

[0245] By inserting the control body 90 thus obtained into a wrapping device to the control body, it is possible to use such a device for winding the new wrapping material.

Claims

CLAIMS1 . Method for changing wrapping material in wrapping devices comprising the following actions: a) providing a winding apparatus comprising: a gripper (20) mechanically connected to one end (21 ) of a tubular shaft (22), wherein said gripper (20) is rotatable and translatable integrally with said tubular shaft (22); an actuating rod (24), active on said gripper (20), slidable with respect to said tubular shaft (22) and rotationally constrained to said tubular shaft (22), wherein said gripper (20) is openable and closable as a result of a translation of said actuating rod (24); a first electric motor (30) active on said actuating rod (24) to translate said actuating rod (24); a second electric motor (31 ) active on said tubular shaft (22) to translate said tubular shaft (22); a control unit (80) configured to drive the first electric motor (30) and the second electric motor (31 ); b) supplying the control unit (80) with at least one input data (ID) representative of a desired operating parameter (DOP) of the gripper (20), wherein said control unit (80) is configured to determine a law of motion of the gripper (20) based on said at least one desired operating parameter (DOP); c) operating the winding apparatus to wind a wrapping material onto a product; d) checking whether the resulting winding meets predetermined requirements; e) if the obtained winding does not meet these predetermined requirements, repeating actions b), c) and d); f) if the winding obtained meets said predetermined requirements, providing a control body (90) with cam paths (95, 96) which implement the law of motion determined by said control unit (80).

2. Method according to claim 1 , wherein said control unit (80) is further configured to determine, from said law of motion of the gripper (20), a first law of motion of the actuating rod (24) and a second law of motion of the tubular shaft (22).

3. Method according to claim 2, wherein providing a control body (90) with cam paths (95, 96) implementing the law of motion determined by said control unit (80) comprises providing a single actuator (91 ) with a first cam path (95) implementing the first law of motion and with a second cam path (96)implementing the second law of motion.

4. Method according to claim 2, wherein providing a control body (90) with cam paths (95, 96) implementing the law of motion determined by said control unit (80) comprises providing a first actuator (92) with a first cam path (95) implementing the first law of motion and providing a second actuator (93) with a second cam path (96) implementing the second law of motion.

5. Method according to any one of the preceding claims, wherein said control unit (80) is configured to interpolate said at least one desired operating parameter (DOP) with preset operating parameters (POP) and determine said law of motion of the gripper (20) based on the result of said interpolation.

6. Method according to claim 2, wherein said control unit (80) is configured to generate a first control signal (CS1 ) representative of the first law of motion and to send it to a driver (82) of the first electric motor (30) and to generate a second control signal (CS2) representative of the second law of motion and to send it to a driver (83) of the second electric motor (31 ).

7. Method according to any one of the preceding claims, wherein said desired operating parameter (DOP) of the gripper (20) is selected from at least one of the following parameters: translation of the tubular shaft (22) along a first direction; translation of the tubular shaft (22) in a second direction; point at which a closing movement of the gripper (20) begins; point at which a closing movement of the gripper (20) ends; point at which an opening movement of the gripper (20) begins; point at which an opening movement of the gripper (20) ends; stroke of the tubular shaft (22) during which a complete closing movement of the gripper (20) takes place; stroke of the tubular shaft (22) during which a complete opening movement of the gripper (20) takes place; tightening torque of the gripper (20).

8. Method according to any one of the preceding claims wherein the action b) comprises providing the control unit (80) with a plurality of input data (ID) each representative of a desired operating parameter (DOP) of the gripper (20).

9. A method according to any one of the preceding claims, wherein said winding apparatus comprises a data input user interface (81 ) configured to receive at least one input data (ID) representative of said desired operating parameter (DOP) of the gripper (20).

10. Method according to claim 9, wherein said data input user interface (81 ) is further configured to receive at least one additional input data (ID) representative of a rotational speed of the gripper (20).11 . Method according to any one of the preceding claims, wherein said winding apparatus comprises a third electric motor (32) active on said tubular shaft (22) to rotate said tubular shaft (22), said control unit (80) being configured to drive said third electric motor (32).

12. Method according to any one of the preceding claims, wherein said tubular shaft (22) is rotatable about an approach axis (A) and translatable along said approach axis (A), wherein said actuating rod (24) is slidable along an actuating axis (B) parallel to, or coincident with, said approach axis (A), wherein said actuating rod (24) is movable along said actuating axis (B) with respect to said tubular shaft (22), and wherein said gripper (20) is openable and closable following a translation of said actuating rod (24) along said actuating axis (B).

13. Method for changing wrapping material in a wrapping device including: a) providing a model of a wrapping device (10) with a cam path control body and provided with a manipulator member (20) configured to contact a wrapping material and perform operations on such wrapping material, wherein in said model of a wrapping device (10) the cam path control body is replaced by a plurality of electric motors (30, 31 ), wherein the number of electric motors (30, 31 ) is correlated to the number of cam paths, wherein said model of wrapping device (10) comprises active kinematic mechanisms between said electric motors and said manipulator member (20), and wherein said model of wrapping device (10) comprises a control unit (80) configured to drive said electric motors; b) providing the control unit (80) with at least one input data (ID) representative of a desired operating parameter (DOP) of the manipulator member (20), wherein said control unit (80) is configured to determine a law of motion of the manipulator member (20) based on said at least one desired operating parameter (DOP); c) operating the wrapping device model to obtain a wrapping material on a product; d) verifying whether the obtained wrapper meets predetermined requirements; e) if the obtained wrapper does not meet these predetermined requirements,repeating actions b), c) and d); f) if the obtained wrapping meets these predetermined requirements, providing a control body (90) with cam paths (95, 96) that implement the law of motion determined by said control unit (80).

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