Electric air pressure gripper

Abstract

To disclose a gripper of an industrial manipulator, more particularly, a device for visually inspecting a transparent or translucent container.SOLUTION: A gripper includes: a body which stores an electric motor; and a rotatable portion which is restrained by the body. The rotatable portion has jaws which mutually approach and separate from each other to hold and release an article. The electric motor has a purpose to apply rotation to the rotatable portion while the article is held between the jaws. The gripper further includes an air pressure actuator for controlling opening of the jaws to release the article, for instance, a piston. An electric actuator and the air pressure actuator do not perform mutual action in a separated state during an operation of the electric actuator. The electric actuator and the air pressure actuator are integrated during an operation of the air pressure actuator.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to electro-pneumatic grippers for industrial manipulators, in particular for devices for inspecting containers and vials in the pharmaceutical industry. [Background technology]

[0002] In the field of industrial automation, the use of grippers in combination with manipulators to grasp, move and release objects is known.

[0003] Grippers for industrial manipulators generally comprise a body and two or more jaws or gripper fingers attached to the body that can be moved apart or towards each other between an open or release position that exerts no force on the item being manipulated, and a closed or gripping position that exerts sufficient force on the item being manipulated to prevent the item from being accidentally released while being gripped.

[0004] Movement of the jaws is achieved by utilizing either an electric actuator, such as an electric motor housed within the body of the gripper, or a pneumatic actuator, for example a cylinder-piston system housed within the body of the gripper and supplied with compressed air.

[0005] Grippers used in inspection machines for the quality control of containers and vials in the pharmaceutical industry are a special case. These machines are optical inspection machines that inspect transparent or translucent vials, bottles and containers placed along a production line, ensuring 100% quality control of the manufactured containers in terms of the integrity of the container and the respective closure, as well as the quantity and purity of the contents. In these machines, several grippers are arranged next to each other, in a line or in a circle, according to a carousel configuration. Each gripper picks up a container and transports it in front of a camera that takes one or more images of the container itself, which are processed by a computer to detect any anomalies. A strobe light is often used to take the images.

[0006] Most often, in this type of inspection device, the gripper is arranged on a carousel structure and, in addition to the conventional opening and closing movement of the gripper, the gripper is required to rotate about its own longitudinal axis, which also corresponds to the axis along which the object is gripped, in order to simultaneously generate a vortex in the liquid contained inside the container / vial to be inspected. The images of the container and the vortex taken by the inspection device make it possible to identify anomalies such as the presence of impurities in the liquid or an excess or deficiency of the liquid's volume, viscosity, etc.

[0007] Because the grippers are adjacent to each other and the space available on the carousel is minimal, grippers that do not have their own actuators are preferred in the above-mentioned inspection apparatus precisely because actuators can adversely affect the overall size of each gripper and ultimately the number of grippers that can be mounted on a carousel. In fact, if the grippers had their own actuators to rotate and open and close the jaws, the overall size of the grippers would be larger than those currently available, and the same carousel, all other things being equal, would necessarily be equipped with fewer grippers.

[0008] In the most widespread solution, the grippers mounted on the inspection device have a stem slidably mounted in a dedicated seat on the gripper's body, which stem is movable on its longitudinal axis between a distal position and a proximal position depending on the force exerted by a cam controlled by another mechanism of the inspection device. In particular, one cam is provided for all grippers. The position of the stem relative to the gripper's body uniquely determines the position of the jaws, i.e. the opening and closing of the jaws is mechanically controlled. In other words, the gripping and release of the containers is controlled by a cam external to the gripper, in particular a cam of the inspection device, which acts on a sliding stem of the respective gripper, which is returned by a suitable spring or other biasing means to an initial position with the jaws closed.

[0009] In another known solution for rotating the jaws and therefore also the container or vial, the rotation of the gripper around its longitudinal axis is achieved by mounting the gripper on a carousel structure of the inspection device and by prearranging an electric motor on the carousel structure for rotating the rotatable part of the gripper including the jaws. The electric motors are connected to one or more grippers respectively by means of a drive belt. The rotation of the pulleys of the electric motors is transmitted by the belt to the rotatable part of the respective gripper, causing the gripper to rotate around its respective longitudinal axis. The rotation speed is typically between 400 and 800 revolutions per minute, but can also reach 3000 revolutions per minute.

[0010] In these conventional solutions, the grippers can be defined as passive grippers since they do not have their own actuators inserted within the body of the gripper for opening and closing the jaws and their respective rotation, and their operation relies on cams and electric motors of the inspection device located in the carousel structure.

[0011] Grippers have also recently been proposed that include their own actuator, ie, an actuator mounted on the gripper, to rotate the jaws.

[0012] Patent application IT202019000002871, filed on 27 August 2019 in the name of the applicant, describes an industrial manipulator, in particular a gripper for a device for visually inspecting transparent or translucent containers, which gripper: - a body having a longitudinal axis and fixable to an inspection device; a rotatable portion constrained to the body and rotatable relative to the body about a longitudinal axis; - an electric motor housed in the body of the gripper and adapted to impart a rotation about a longitudinal axis to the rotatable part; - jaws attached to the rotatable part and movable relative to the rotatable part so that they can move towards and away from each other to lift and release, i.e. open and close, containers or vials; - drive means for controlling the opening and closing of the jaws in response to a force exerted by an actuator of the inspection device, i.e. an actuator external to the gripper; Equipped with.

[0013] More specifically, the gripper comprises a hollow drive shaft arranged on the longitudinal axis of the gripper. The hollow drive shaft is connected to a rotatable part of the gripper, so that a rotation imparted to the drive shaft by an electric motor with respect to the longitudinal axis is transmitted to the jaws. The longitudinal axis of the gripper is therefore also the axis of rotation of the jaws. A control rod of the jaws is housed telescopically, i.e. slidably, inside the drive shaft and precisely serves to open the jaws. The displacement of the control rod relative to the drive shaft is provided by an external actuator, for example a cam of an inspection device to which the gripper is attached. When the force exerted by the cam on the control rod is removed, an elastic member causes the jaws to automatically return to close.

[0014] IT102009901732640, filed on 15 May 2009 in the name of Pharmamech, describes the gripper itself, with an actuator that provides the rotation of the jaws and controls their opening. In particular, this document describes two embodiments of a gripper configured for manipulating test tubes or vials in an inspection device for quality control. With reference to the respective figures, both embodiments comprise an actuator, coaxial with the axis of the gripper, which controls both the rotation of the jaws and their respective opening and closing. In particular, the actuator controls an outer shaft 8 and a control rod 10, which are arranged coaxially. The outer shaft 8 is hollow, into which the control rod 10 is inserted so as to slide telescopically. In the first embodiment, the outer shaft 8 is a drive shaft that is rotated by the actuator when the gripper is closed, rotating the test tube or vial and allowing inspection with optical systems. To open the jaws and release the test tube / vial when the gripper is stationary, the control rod 10 is actuated, i.e. it is translated relative to the drive shaft 8. In a second embodiment, the actuator is shown as a "rotary actuator device" 14, which acts only on the control rod 10, which is allowed to both translate relative to the drive shaft 8 to open and close the gripper, and rotate to rotate the test tube / vial, while the drive shaft 8 remains idle.

[0015] CN1111353 describes a gripper whose opening and closing are controlled by an axial stem which in turn is controlled by an off-axis actuator and whose rotation is imparted by a belt pulley system.

[0016] US 2008 / 0085507 describes a rotating gripper with three jaws whose opening and closing are controlled by the same axial motor that controls the rotation of the gripper, but whose movement is achieved by using spur gears to rotate the jaws about an axis parallel to the axis of the gripper.

[0017] US2009 / 0179445 describes a gripper with two motors: a first rotary motor rotates the jaws by imparting rotation to a hollow drive shaft, shown at 20 in the figures, and a second linear motor, shown at 22 in the figures, is housed in the drive shaft 20 and acts as a telescoping push rod to open and close the jaws.

[0018] WO 2023 / 084350 in the name of the applicant describes a gripper comprising a body having a longitudinal axis, a rotatable part constrained to the body so that it can rotate about the longitudinal axis, an electric motor imparting rotation to the rotatable part, and jaws attached to the rotatable part and operable to move towards and away from each other in order to lift and release an object. The electric motor is a single motor housed in the body of the gripper. In particular, the electric motor is capable of rotating the jaws about the longitudinal axis of the gripper by imparting rotation to a drive shaft connected to the upper part with its axis coinciding with the longitudinal axis. The assembly formed by the electric motor and the drive shaft is translatable along the longitudinal axis in response to a thrust provided by an actuator external to the gripper, in particular an actuator of an inspection device to which the gripper is attached, thereby imparting a movement of the jaws towards and away from each other, thus opening and closing the jaws. Summary of the Invention

[0019] The object of the present invention is to provide an electric gripper, i.e. an electric gripper equipped in itself with an electric motor for imparting rotation of the jaws and the object to be manipulated, which is simple and compact to manufacture and at the same time is adapted to control the opening and closing of the jaws without the need for specific actuators external to the gripper, in particular without the need for cams or drive belts of the inspection device to which the gripper is attached.

[0020] In other words, the present invention aims to provide a gripper which itself comprises the necessary means for imparting rotation to the jaws and for controlling the opening and closing movement of the jaws, and which is compatible with known grippers, so that the overall dimensions of the gripper are equal to or smaller than those of known grippers, so that the gripper can be subsequently replaced and installed without modifying the inspection equipment on which the gripper is to be assembled.

[0021] The invention therefore relates to a gripper for an industrial manipulator according to claim 1.

[0022] That is, the present invention provides: a body having a longitudinal axis and intended for fixing to an external device, such as an inspection device for inspecting vials and containers, in particular a carousel structure, - a first electric actuator housed in the body of the gripper so as to remain within the overall dimensions of the body; a rotatable portion constrained to the body and rotatable relative to the body about a longitudinal axis; - jaws attached to the rotatable portion and operable to move toward and away from each other to open and close the gripper and thus hold and release the article; The present invention relates to a gripper equipped with

[0023] The gripper also includes a control shaft that engages the jaws to control the movement of the jaws toward and away from each other. The control shaft is coupled to an electric actuator such that the control shaft: - rotatable about a longitudinal axis by an electric actuator for rotating the rotatable part and the jaws present on said rotatable part; and - translatable on the longitudinal axis to move the jaws closer together or farther apart and thus open or close the gripper;

[0024] Rotation of the rotatable portion together with an article held by the jaws is caused by rotating the control shaft, and opening of the jaws and release of the article is caused by translating the control shaft, and the gripper is prepared to pick up a new article.

[0025] The gripper also includes a second pneumatic actuator housed in the body, the pneumatic actuator including a piston movable within a cylinder between bottom dead center pmi and top dead center pms in response to pressure applied by external means, for example compressed air supplied to the gripper by a pneumatic line of the inspection apparatus.

[0026] The piston is configured to interact with the control shaft and thus functionally constrains itself relative to the piston for at least a portion of the piston's movement, the functional constraint being the piston's ability to impart a thrust force to the control shaft to cause it to translate along its longitudinal axis.

[0027] In this manner, movement of the piston between bottom dead center pmi and top dead center pms causes the control shaft to translate on its longitudinal axis, causing the jaws to open if the gripper is normally closed, or to close if the gripper is normally open.

[0028] The two actuators, the electric actuator and the pneumatic actuator, remain separate and do not interact while the electric motor is operating, i.e. while the jaws continue to rotate, whereas, at least during translation, the electric actuator and the pneumatic actuator are united while the pneumatic actuator is operating, i.e. when compressed air is supplied to the pneumatic actuator to open the jaws. These two states do not occur simultaneously, but alternate between one and the other, and while the jaws rotate about the longitudinal axis, they cannot open to release the article.

[0029] The above solution has distinct advantages over known grippers.

[0030] A first advantage is obtained by the complete compatibility of the gripper with known art grippers used in inspection devices for inspecting containers and vials, due to the fact that the gripper according to the invention can be formed with a body having the same outer diameter as the body of the known gripper.

[0031] A second advantage is that the gripper is provided with two actuators, one electric and the other pneumatic, instead of the actuators typically provided in the inspection device or machine in which it is provided, which allow the jaws to be provided with the movements required to lift / release the object and to rotate it, depending on the actuator, without the device in which the gripper is provided. This situation then allows the creation of the simplest inspection devices and machines, without parts such as belts that wear out and cause the emission of particles into the air.

[0032] A third advantage is that the use of two actuators, one electric and one pneumatic, allows for a mechanically simpler gripper than a solution using a single rotary translating actuator.

[0033] The structure of the gripper is relatively simple, since it does not have a coaxial shaft, as is the case with known prior art solutions, and therefore allows for a quick assembly without excessive costs.

[0034] In a preferred embodiment, the electric actuator is an electric motor, e.g. with a cylindrical body, having a drive shaft extending on a longitudinal axis and rotatable about said longitudinal axis. The drive shaft of the electric motor is rotationally integrated with the control shaft, in the sense that the two shafts are coupled so as to rotate together (simultaneously). Alternatively, the control shaft and the drive shaft can be the same component, i.e. the control shaft can be part of the drive shaft. However, a preferred solution is for these shafts to be separate and continuously joined, which is the more practical solution.

[0035] For example, the control shaft and the drive shaft are butt-coupled in a non-telescopic, non-coaxial arrangement such that the control shaft constitutes an extension of the drive shaft on the longitudinal axis, and the coupling can be accomplished by threading, mechanical interference, or the like.

[0036] In a preferred embodiment, the electric motor is slidably accommodated within the body of the gripper and is translatable along the longitudinal axis between a bottom dead center pmi and a top dead center pms in response to a force provided by the pneumatic actuator. In other words, the electric motor floats within the body of the gripper. Depending on whether the gripper is in a normally open or closed state, the bottom dead center pmi of the electric motor corresponds to a mutual position of one of the jaws selected from the approach position and the separation position, and the top dead center pms of the electric motor corresponds to a mutual position of the other of the jaws selected from the approach position and the separation position.

[0037] Axial displacement of the electric motor produces a corresponding axial displacement of the control shaft.

[0038] An elastic element is operatively interposed between the body and the electric motor, which opposes the translation of the electric motor on the longitudinal axis and returns the electric motor, upon the cessation of the thrust exerted by the pneumatic actuator, to an initial axial position, or at least to a retracted position different from the initial position and corresponding to the jaws pressing against the article, which retracted position depends on the overall dimensions of the article and therefore on the distance between the jaws gripping the article.

[0039] The gripper is preferably configured to be normally closed, the elastic element being a spring housed in the body between the rotatable part and the electric motor, the spring being preloaded to always exert a thrust on the electric motor in a direction that moves it to the bottom dead center pmi, so that the jaws approach each other and close against the item to be manipulated.

[0040] The spring is preferably disposed coaxially with the longitudinal axis and more preferably surrounds the control shaft.

[0041] In a preferred embodiment, the gripper comprises a sleeve that is constrained to the electric motor, the sleeve being arranged coaxially with both the drive shaft and the control shaft, as well as with the elastic element. For example, a spring is housed in the sleeve and the control shaft is inside the spring. The sleeve contacts the end of the gripper's body when the electric motor is at top dead center pms, thus defining the limit stop. In other words, the sleeve is integral with the electric motor and acts like a spacer against the end of the gripper's body when the electric motor is pushed to top dead center pms.

[0042] The gripper comprises a number of radial pins, each inserted into a through hole drilled in a side wall of the gripper body, to prevent the sleeve from rotating around the longitudinal axis. The sleeve comprises an elongated slot in the direction of the longitudinal axis for each radial pin. The radial pins are fixed by fitting into the respective through holes and are each at least partially inserted into the corresponding elongated slot. In other words, the radial pins simultaneously engage with the gripper body and the sleeve slot, thereby preventing the sleeve from rotating (anti-rotation function). The sleeve's axial limit stop corresponds to the radial pin abutting one of the two ends of the corresponding elongated slot. In other words, the radial pins prevent the sleeve from rotating, but allow the sleeve, together with the motor, to move axially with a stroke length corresponding to the extent of the slot in the direction of the longitudinal axis.

[0043] The jaws are slidably accommodated in corresponding guides, e.g. radial guides, of the rotatable part. There may be two jaws, or more than two, e.g. three.

[0044] In a preferred embodiment, the jaws are two and slide in the same guide perpendicular to the longitudinal axis. The gripper comprises a lever for each of the jaws, which is pivoted on a rotatable part and swings in a plane parallel to the longitudinal axis. The swinging of the levers is controlled by a control shaft, the end of which is slidably inserted in the rotatable part and engages with the levers, so that the angular position of each lever uniquely corresponds to the axial position of the control shaft. For example, the end of the control shaft can comprise a groove into which the lever is inserted, or alternatively the end of the shaft can be hinged or connected to the lever.

[0045] The transmission of rotation from the control shaft to the pivotable part can be achieved in two ways.

[0046] - in a first method, the gripper comprises a pin inserted radially through the control shaft, the pin transmitting the rotation about the longitudinal axis by engaging in a slot in the rotatable part, the pin sliding in the slot in the direction of the longitudinal axis, the axial extent of the slot being equal to or greater than the axial movement of the control shaft;

[0047] In a second method, at least a portion of the control shaft which engages with the rotatable part has a non-circular cross-section, for example a polygonal shape, and engages with a corresponding non-circular guide, for example a guide of a complementary shape, in the rotatable part.

[0048] In either case, rotation imparted to the control shaft by the electric motor is transmitted to a rotatable part which rotates about a longitudinal axis relative to the body of the gripper, the control shaft further sliding inside the rotatable part to actuate the jaws.

[0049] In a preferred embodiment, an end of the control shaft protrudes from the body of the gripper and engages the rotatable portion. The control shaft is telescopically movable relative to the gripper body between retracted and extended positions, which correspond to jaws close together and jaws spaced apart depending on whether the gripper is normally closed (preferred state) or normally open (reverse operation).

[0050] In the context of a pneumatic actuator, the piston includes a thrust section or rod. At bottom dead center (PMI) of the piston, the rod is separated from the electric actuator and therefore does not contact and exert no thrust on the electric actuator. At top dead center (PMS) of the piston, the rod abuts the electric actuator and exerts an axial thrust on the electric actuator, which translates the electric actuator within the body of the gripper, thereby extending the control shaft and actuating the jaws.

[0051] In a preferred embodiment, as mentioned above, the electric actuator is an electric motor with a drive shaft rotatable about a longitudinal axis, the drive shaft passing through the electric motor, i.e. one end of the drive shaft projects towards the control shaft and the other end of the drive shaft projects towards the pneumatic piston, in particular towards the rod of said piston, the rod of said pneumatic piston being capable of abutting against a corresponding end of the drive shaft when said pneumatic piston is pushed by compressed air, in this situation the electric motor is deactivated and the drive shaft is not rotating.

[0052] In particular, at the bottom dead center of the pneumatic piston, the rod is separated from the drive shaft, does not contact the drive shaft, and is decoupled from rotation from the drive shaft. Thus, in this configuration, the rotation imparted to the drive shaft by the electric motor cannot be transmitted to the rod of the pneumatic piston, and as a result, the pneumatic piston does not rotate about its longitudinal axis. In this situation, the electric motor can be operated to rotate the drive shaft.

[0053] To oppose the axial displacement of the pneumatic piston, an elastic element is preferably operatively interposed between the electric actuator and the pneumatic piston, the elastic element being preloaded and constantly exerting a thrust on the piston in a direction away from the electric actuator in order to return the piston to bottom dead center pmi when the supply of compressed air is stopped.

[0054] In a preferred embodiment, the gripper operates as follows: the jaws are normally closed and must be spread apart to allow the insertion of an article to be lifted between them. The movement of the jaws apart is achieved by supplying compressed air to the pneumatic actuator, without deactivating the electric motor and thus rotating the drive shaft. The compressed air pushes the pneumatic piston to its top dead center, which determines the axial displacement of the linkage mechanism made up of the electric actuator, the control shaft, the lever and finally the jaws. Once the article is inserted between the jaws, the supply of compressed air is interrupted and the elastic element moves the above-mentioned linkage mechanism in the retracting direction, and the pneumatic piston returns to its bottom dead center. Meanwhile, the electric actuator and the control shaft close the jaws against the article and do not return to their initial point, since the overall dimensions of the article determine the return movement of the electric actuator and the control shaft. The thrust exerted by the elastic element around the control shaft causes the jaws to continue to press against the article and to hold it. At this point, the electric motor can be operated to rotate the drive shaft and the control shaft, resulting in rotation of the rotatable portion of the gripper and the article held between the jaws. At the end of the operation, the electric motor is deactivated to stop the rotation, and the article can be released by supplying compressed air to the pneumatic actuator to open the jaws as described above. In this respect, the rotation of the drive shaft and the control shaft and the translation of these two shafts are asynchronous, i.e., they do not occur simultaneously. Further features and advantages of the present invention will become more apparent upon consideration of the following detailed description of preferred but non-exclusive embodiments, illustrated in a non-limiting manner with the aid of the accompanying drawings, in which: FIG. 1 is a perspective elevational view of an inspection apparatus for inspecting vials, including a gripper according to the prior art and a gripper according to the present invention. FIG. 2 is an exploded view of a gripper according to the present invention. FIG. 3 is a perspective view of the gripper shown in FIG. FIG. 4 is an axial cross-sectional view of the gripper shown in FIG. 2 with the jaws approaching or closed. FIG. 5 is an axial cross-sectional view of the gripper shown in FIG. 2 with the jaws spaced apart or open. FIG. 6 is a perspective view of the gripper shown in FIG. 2 with the jaws approaching or closed, as well as a perspective view of a container being lifted. FIG. 7A is an axial cross-sectional view of the gripper shown in FIG. 2 with the jaws approaching or closed in the configuration shown in FIGS. FIG. 7B is an enlarged view of the area enclosed by the dotted line frame in FIG. 7A. FIG. 8 is a perspective view of the gripper shown in FIG. 2 with the jaws spaced apart or open and a container being lifted and inserted between the jaws. FIG. 9A is an axial cross-sectional view of the gripper shown in FIG. 2 with the jaws spaced apart or open in the configuration shown in FIGS. FIG. 9B is an enlarged view of the area enclosed by the dotted line frame in FIG. 9A. FIG. 10 is a perspective view of the gripper shown in FIG. 2 with the jaws closed against a container to be lifted and rotated. FIG. 11A is an axial cross-sectional view of the gripper shown in FIG. 2 in the state shown in FIG. 10, with the gripper closed against a container. FIG. 11B is an enlarged view of the area enclosed by the dotted line frame in FIG. 11A. FIG. 12A shows a perspective view of a gripping hand of a manipulator in a first state, the gripping hand being equipped with a different embodiment of a gripper according to the prior art for screwing and unscrewing container caps. FIG. 12B is an enlarged view of the portion enclosed by the dotted line in FIG. 12A. FIG. 13A is a perspective view of the gripper hand shown in FIG. 12A in a second state. FIG. 13B is an enlarged view of the portion enclosed by the dotted line in FIG. 13A. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0055] In the drawings, the terms top, upper, lower and lower should be understood to refer to the orientation that the gripper has in the drawing itself.

[0056] 1 shows in a perspective view a carousel structure 500 of an inspection device for inspecting vials or containers V (hereinafter simply containers V). The carousel structure 500 comprises a circular frame 501 intended to rotate to carry the containers V in front of an optical image acquisition and processing system for inspecting the quality of the containers V and their respective contents.

[0057] The gripper 502 according to the known art and the two grippers 1 according to the invention are installed at a regular pitch around the circumference of the circular frame 501, so that Fig. 1 makes it possible to relate and compare the use of the gripper 502 and the gripper 1. Each of the grippers 1, 502 holds a container V, while the circular frame 501 is rotated around its own axis.

[0058] As regards the grippers 502 according to the known art, each gripper 502 comprises a body 503 fixed to the circular frame 501 without the possibility of relative movement and a part 504 rotatably constrained to the body 503. Electric motors 505, in particular one electric motor 505 for each of the two grippers 502, are fixed to the circular frame. Each electric motor 505 is connected to the two grippers 502 by means of a toothed belt 506 and a toothed pulley 507, which together define a drive system. The toothed pulley 507 is rotatable relative to the body 503 of the respective gripper 502 about the longitudinal axis of the gripper 502, the rotation of the toothed pulley 507 being imparted by the electric motor 505 by means of the toothed belt 506, causing a rotation of the rotatable part 504 relative to the body 503 of the gripper 502 and thus of the container V. The opening and closing of the jaws 508 of the grippers 502 is controlled by an actuator (not visible in FIG. 1) internal to each gripper 502 .

[0059] As regards the grippers 1 according to the invention, as can be seen in Fig. 1, these grippers 1 are not combined with the electric motors 505 of the inspection device. The grippers 1 are connected to a compressed air source by respective connecting pipes 509 and to a power supply by electric wires 510. It is important to note that the grippers 1 according to the invention are fully compatible with the grippers 502 according to the known art and can therefore be used to retrofit existing inspection devices, simplifying the precise installation of the carousel structure. In fact, by equipping the circular frame 501 with only the grippers 1 instead of the grippers 502, it is not necessary to mount the electric motors 505, the toothed belts 506 and the gears 507. This achieves a significant structural simplification, with almost no overall dimensions in the area above the circular frame 501, which not only limits the weight of the carousel structure, but also eliminates the need to use rubber belts in the carousel structure, which are prone to wear forming rubber particles that soil the structure and the containers, improving cleanliness. The reduced weight of the circular frame 501 results in a corresponding reduction in the inertia of the system during acceleration and braking, which in turn increases the productivity of the inspection apparatus, allowing it to check more batches of containers V per unit of time, all other factors being equal.

[0060] FIG. 2 shows an exploded view of a gripper 1 for an industrial manipulator according to the invention, in particular configured to be mounted on an inspection device for inspecting transparent or translucent containers V, for example in the pharmaceutical industry.

[0061] FIG. 3 is a perspective view of the assembled gripper 1.

[0062] 2 and 3, the gripper 1 comprises a body 2 that can be fixed to an external structure, such as for example the circular frame 501 shown in Fig. 1. The body 2 defines a longitudinal axis XX of the gripper 1. In the embodiment shown, the body 2 is cylindrical and hollow to accommodate certain components of the gripper 1.

[0063] The gripper 1 further comprises an end part 3 extending in a cantilevered manner from one end of the body 2, which end part 3 is therefore rotatably constrained to the body 2 and can rotate about a longitudinal axis XX, but not freely, under conditions to be described later. The end part 3 is hereinafter referred to as the rotatable part 3.

[0064] In general, the gripper 1 can have several jaws, for example three or four jaws, and in the illustrated embodiment 1 there are two jaws, identified by the reference numbers 4 and 5. The jaws 4 and 5 slide in guides 6 of the rotatable part 3, which extend perpendicularly to the longitudinal axis XX, i.e. radially. The jaws 4 and 5 are thus allowed to move in the guides 6, moving closer together to close the gripper 1 and lift the container V, and moving apart to open the gripper 1 and release the container V. Such a configuration is not the only one possible, and indeed the gripper 1 can also have jaws 4 and 5 pivoted to the rotatable part 3 and swingable relative to the rotatable part 3, rather than sliding in guides.

[0065] More specifically, jaws 4 and 5 are radially movable between a proximal position relative to the longitudinal axis XX corresponding to a gripping position of a container V or a general article, and a distal position relative to the longitudinal axis XX corresponding to a release position of the container V or an article.

[0066] The thrust for moving the jaws 4 and 5 in the guide 6 is provided by corresponding levers 4' and 5' pivoted to the rotatable part 3 by means of pins 7 and 8. The pins 7 and 8 are mounted offset from the longitudinal axis XX, in other words such that the levers 4' and 5' oscillate in a plane parallel to the longitudinal axis XX, in particular in the illustrated example, in a plane containing the longitudinal axis XX.

[0067] A ball or roller type bearing 9 is accommodated in a corresponding seat 9' in the body 2 of the gripper 1, the function of which is to allow rotation of the rotatable part 3 about the longitudinal axis XX relative to the body 2. A washer or ring nut used to hold the bearing 9 in the seat 9' is designated with the reference 9'', which fits into a corresponding cross-sectional narrowing (barely visible in the figure) of the control shaft 10.

[0068] The gripper 1 further comprises a control shaft 10 coaxially and telescopically accommodated in the body 2. The control shaft 10 has two functions, each of which is asynchronous, and which alternatively controls the rotation of the rotatable part 3 and the opening and closing of the jaws 4, 5. In particular, the control shaft 10 is coaxial with the body 2 in the sense that it extends along a longitudinal axis XX and is allowed to rotate clockwise and / or counterclockwise about the same longitudinal axis XX in response to a thrust provided by an electric motor, as will be described below. The control shaft 10 is accommodated almost entirely within the body 2, except for one end 10', which protrudes from the body 2 and is inserted into the rotatable part 3 through an opening 3' which also acts as a guide for the end 10'. Two diametrically opposed pockets 11 are present at the end 10' of the control shaft 10 and engage with a corresponding lever 4' or lever 5', respectively.

[0069] The control shaft 10 is also permitted to translate alternately on the longitudinal axis XX between a retracted position and an extended position, as will be described below.

[0070] Axial displacement of the control shaft 10 towards the extended position moves the end 10' away from the body 2, resulting in the jaws 4 and 5 moving apart and the gripper 1 opening, and conversely, axial displacement of the control shaft 10 towards the retracted position moves the end 10' towards the body 2, resulting in the jaws 4 and 5 moving closer together, i.e., the gripper 1 closing.

[0071] In fact, as can be seen, lever 4' and lever 5' each have two lobe portions 12, 13, one lobe portion 12 for engaging with the corresponding jaw 4, 5 and the other lobe portion 13 for engaging with a corresponding pocket 11 present in the control shaft 10.

[0072] To prevent the rotatable part 3 from separating from the body 2 of the gripper 1 and to maintain the connection with the control shaft 10, specifically to hold the rotatable part 3 on the control shaft 10, the gripper 1 is provided with a retaining pin 14, which is radially inserted into a corresponding slot 15 in the rotatable part 3 and into a corresponding radial hole 16 in the control shaft 10.

[0073] As can be seen, the slot 15 is elongated in the direction of the longitudinal axis, the reason for this configuration being the fact that the control shaft 10, as described above, is permitted to translate axially and is therefore telescopic with respect to the body 2, while the axial position of the rotatable part 3 with respect to the body 2 remains unchanged. The slot 15 thus allows the retaining pin 14 to move therein in order to support the translation of the control shaft 10 between the retracted and extended positions, without transmitting undesirable forces to the rotatable part 3. On the other hand, the retaining pin 14 transmits rotation, precisely in the sense that it enables the transmission of a rotation imparted to the control shaft 10 about the longitudinal axis XX to the rotatable part 3.

[0074] In a non-illustrated embodiment, as an alternative to the use of a pin 14 for binding the control shaft 10 to the rotatable part 3 and for integrating these two parts in rotation about the longitudinal axis XX, the control shaft 10 is formed with an end 10' having a polygonal cross section, for example a square, hexagonal, etc. cross section, and the opening 3' of the rotatable part 3, which guides the end 10' of the control shaft 10, is formed with a cross section complementary to that of the end 10'. With this detail, when the control shaft 10 rotates about the longitudinal axis XX, the control shaft 10 rotates the rotatable part 3 without the use of a pin 14, due to the geometric coupling between the end 10' and the opening 3'. This detail does not affect the axial movement of the control shaft 10 relative to the rotatable part 3. The anti-rotation function is therefore achieved in an alternative manner to that described above.

[0075] The axial movement of the control shaft 10 is opposed by a resilient element, which in the illustrated example is a spring 17, which fits coaxially on the control shaft 10. The gripper 1 is preferably constructed so that the closed position of the jaws 4 and 5 is the normal position, i.e. the gripper is normally closed, and the opening, i.e. the separation of the jaws 4 and 5, occurs only in response to the axial movement of the control shaft 10 towards the extended position. The spring 17 is thus preloaded and inserted into the body 2 so as to be operatively interposed between the end of the body 2 and the control shaft 10, and constantly exerts a force on the control shaft 10 which holds or returns it to the retracted position.

[0076] The normally closed state of gripper 1 is a safe choice from a safety point of view, since it ensures that jaws 4 and 5 maintain grip on container V even when air pressure is not supplied to gripper 1. Obviously, it is also possible to have the gripper in the opposite state, i.e. normally open, with an actuation to close the gripper, but this option may result in less safety and increased energy consumption.

[0077] A sleeve 18 is also accommodated inside the body 2, coaxially with the body 2, the control shaft 10 and the spring 17, and is located radially outward with respect to the control shaft 10 and the spring 17, respectively. The sleeve 18 slides axially in the body 2 of the gripper 1 between the bottom dead center and the top dead center by a length at least corresponding to the movement of the control shaft 10 between the retracted and extended positions, the inner surface of the body 2 acting as a cylinder in which the sleeve 18 slides. To prevent rotation of the sleeve 18 about the longitudinal axis XX, said sleeve 18 is prevented from rotation by pins 19 (there are three in the illustrated example, arranged at an angle of 120°). The pins 19 are inserted in radial holes 20 drilled through the side wall of the body 2 of the gripper 1 and extend for a length that respectively engages with corresponding slots 21 formed in the side wall of the sleeve 18. The slots 21 extend axially to allow axial translation of the sleeve 18, as described above.

[0078] Inside the main body 2, there is a single electric motor M located below the control shaft 10 as viewed in the figure. The drive shaft 22 of this electric motor M has an axis that coincides with the longitudinal axis XX and is fixed to the control shaft 10 by butt-jointing, for example by screwing, so that the drive shaft 22 and the control shaft 10 are integrated when rotating and translating. The outer diameter of the electric motor M is slightly smaller than the inner diameter of the main body 2 of the gripper 1, so that the axial displacement of the motor M is not hindered by contact with the main body 2. The travel distance of the electric motor M in the main body 2 is 5 mm to 15 mm, preferably 8 mm. In this way, the electric motor M is in a floating state within the main body 2.

[0079] The sleeve 18 serves as an upper abutment for the electric motor M and is axially translatable within the body 2. When the sleeve 18 abuts against the end of the body 2 at which the rotatable part 3 resides and reaches top dead centre for said sleeve 18, the electric motor M reaches a limit stop and can no longer move forward. At this point, the sleeve 18 serves as a spacer, thereby preventing excessive compression of the spring 17 and thus the limit stop being exceeded in the extended state due to excessive thrust against the bearing 9 and the control shaft 10.

[0080] The upper end of the electric motor M remains in contact with the sleeve 18 at its periphery, and the drive shaft 22 protrudes and remains in contact with the lower end of the control shaft 10 .

[0081] The drive shaft 22 extends from one end of the electric motor M to the other end, i.e., serves as a through shaft. In particular, the lower end of the drive shaft 22 remains flush with the lower surface of the electric motor M.

[0082] The electric motor M, preferably of the brushless type, is powered by an electric line 510 as shown in Figure 1. Activation of the electric motor M causes a clockwise or counterclockwise rotation of the drive shaft 22, which in turn causes a rotation of the control shaft 10 and the rotatable part 3 on which the jaws 4 and 5 are provided. A first linkage mechanism thus consists of the assembly of these elements M, 22, 10, 3-5, 4', 5', and activation of the electric motor M causes a rotation of the jaws and therefore of the container V, if the latter is held on the longitudinal axis XX.

[0083] The body 2 of the gripper 1 is closed at the bottom by a cap 23 provided with an axial through hole 24 .

[0084] The gripper 1 further comprises means intended for controlling the opening movement of the jaws 4 and 5, as will be explained below, and in particular a pneumatic actuator 25 intended for this function.

[0085] The pneumatic actuator 25 comprises a piston 26 with a rod 27 and a corresponding cylinder 28. In the illustrated example, the cylinder 28 is a cylindrical member that can be screwed to the lower part of the body 2 of the gripper 1. The rod 27 of the piston 26 is slidably inserted into the axial through hole 24 of the cap 23. The cylinder 28 faces upward in FIG. 1 and reaches below the piston 26 a compressed air connection pipe 509 inserted into the joint 31 to supply compressed air into the cylinder 28. The piston 26 is axially inserted into the cylinder 28 and can reciprocate in two directions along the longitudinal axis in response to the thrust of compressed air appropriately supplied by the connection pipe 509 shown in FIG. 1. The rod 27 of the piston 26 faces the electric motor M. A single-lip type or O-ring type gasket 29 surrounds the piston 26 and ensures a tight seal with the cylinder 28.

[0086] Thus, in the example shown, the volume through which the piston 26 moves is bounded on the bottom and sides by the cylinder 28 and on the top by the cap 23 .

[0087] Cylinder 28 should be considered part of body 2 even if it is threaded or otherwise secured to body 2 .

[0088] Between the piston 26 and the electric motor M, specifically between the rod 27 of the piston 26 and the drive shaft 22 of the electric motor M, there is a spring 30, which is arranged coaxially with these elements. The rod 27 of the piston 26 and the drive shaft 22 of the electric motor M are not integrated in the sense that they are not fixed to each other, and axial movement between these elements is possible, as described below.

[0089] FIG. 4 is an axial section of the gripper 1, specifically a section seen on a plane including the longitudinal axis XX and the central axis for the jaws 4, 5. The gripper 1 is shown in the closed state, i.e. with the jaws 4, 5 approaching each other. In this configuration, the piston 26 is at bottom dead center pmi in the cylinder 28, which is not supplied with compressed air. The rod 27 of the piston 26 is separated from the drive shaft 22 of the electric motor M, so that the rotation that the electric motor M can impart to the drive shaft 22 is not transmitted to the piston 26, but only to the rotatable part 3, as described above. The springs 30 and 17 are then stretched, the sleeve 18 and the electric motor M are retracted inside the body 2, and the control shaft 10 is held by the spring 17 in its retracted position, so that the levers 4' and 5' swing one towards the other, bringing the jaws 4 and 5 closer together. The retaining pin 14 rests at its lower limit stop in a slot 15 in the rotatable part 3. A spring 17 exerts a constant thrust and holds the control rod 10 in the retracted position in the absence of any applied force. As mentioned above, the gripper 1 is normally closed, as shown in figure 4.

[0090] FIG. 5 is an axial cross-sectional view of the gripper 1 shown in an open state, which is another state of the normally closed configuration and occurs only during a command and a predetermined time. The piston 26 is at top dead center pms in the cylinder 28 due to the pressure applied by compressed air supplied from the line 509 through the coupling 31 on command. This causes the rod 27 of the piston 26 to be fully raised and butt-coupled to the motor shaft 22 of the electric motor M. The springs 17 and 30 are compressed, and the sleeve 18 is also at its top dead center pms. In particular, the thrust force exerted by the piston 26 through the second interlocking mechanism including the rod 27 and the drive shaft 22 overcomes the force always exerted by the spring 17 to hold the gripper in the normally closed state described with reference to FIG. 4. Thus, the control shaft 10 is pushed by the rod 27 of the piston 26 to extend outward from the body 2, displacing the levers 4' and 5' to an angular position corresponding to the jaws 4 and 5 spaced apart, as shown in Figure 5. The retaining pin 14 is at its upper limit stop in the slot 15 of the rotatable part 3. The gripper can be selectively put into an open position with the jaws 4 and 5 spaced apart by compressed air and a pneumatic actuator 25. The electric motor M is deactivated and does not impart rotation to the drive shaft 22.

[0091] Thus, in effect, in the configuration shown in FIG. 4, the control shaft 10 can rotate about the longitudinal axis XX but cannot translate, and in the configuration shown in FIG. 5, the control shaft 10 can translate on the longitudinal axis XX but cannot rotate.

[0092] 6 is a perspective view of the gripper 1 and a container V placed next to it. The gripper 1 is in a normally closed state with jaws 4 and 5 close to each other. The electric motor M is deactivated and has no current. The jaws 4 and 5 are shaped to be complementary to the outer shape of the container V.

[0093] Figure 7A shows the gripper 1 in the same state as in Figures 4 and 6, i.e. in the closed state, but inverted from the way the gripper 1 is seen attached to the circular frame 501 in Figure 1. The electric motor M is simply simplified. The circular frame 501 then stops so that a container V can be inserted between the jaws 4, 5 after opening them, as shown in Figure 8, and the piston 26 is at the bottom dead center pmi.

[0094] Figure 7B is an enlarged view of the area indicated within the dotted box in Figure 7A, detailing the portion of the gripper 1 where the rod 27 of the piston 26 and the drive shaft 22 of the electric motor remain opposed and separated. As can be seen, there is indeed a gap between the end of the rod 27 and the end of the drive shaft 22, and the two shafts do not touch each other.

[0095] Figure 8 is a perspective view of the gripper 1 and a container V inserted but not held between jaws 4 and 5. The gripper 1 is in an open state, in particular in a maximally open state, with jaws 4 and 5 in their farthest position. As can be seen, jaws 4 and 5 protrude slightly from guides 6 of the rotatable part 3. The container V is pressed between jaws 4 and 5 by external means. Thus, in Figure 8, a gap exists between jaws 4, 5 and container V to allow a correct insertion.

[0096] FIG. 9A shows the gripper 1 in the same state as in FIGS. 5 and 8, i.e. in the open state, but the gripper 1 is inverted from the way the gripper 1 is attached to the circular frame 501 in FIG. 1. The electric motor M is merely simplified. At this time, the container V is inserted between the jaws 4 and 5 as shown in FIG. 8. Compressed air is supplied into the cylinder 28, and the piston 26 is at the top dead center pms, so that the rod 27 is in a position where it is maximally extended outside the cylinder 28. Looking at the lower part of FIG. 9A, it can be seen that there is a gap between the container V and the widely opened jaws 4, 5. The end 10' of the control rod 10 is in a position where it is almost inserted between the jaws 4 and 5.

[0097] The piston 26 is configured to interact with the control shaft 10 for at least a portion of the movement of the piston 26. In particular, the piston 26 may be operatively constrained to the control shaft 10 so as to impart a longitudinal thrust to the control shaft 10, causing longitudinal translation thereof, as described below.

[0098] Figure 9B is an enlarged view of the area indicated in the dotted box in Figure 9A and shows in detail the part of the gripper 1 where the rod 27 of the piston 26 and the drive shaft 22 of the electric motor are butt-coupled in abutment. The spring 30 is compressed and the rod 27 of the piston 26 actually pushes the entire drive shaft 22 and the electric motor M to the top dead center in the body 2. In this way, the control shaft 10 can be pushed longitudinally by the piston 26 resting on it.

[0099] FIG. 10 is a perspective view of the gripper 1 and a container V inserted and held between jaws 4 and 5. The gripper 1 is in a closed state, in particular not in the maximally closed state as shown in FIGS. 4, 6, 7A and 7B, but in a state between the previously shown states, and the jaws 4 and 5 are not in a position of minimum separation, since the container V must be present between them and pressure must be applied to hold the container V. In this regard, the spring 17 serves to apply the necessary force to the jaws 4 and 5 to exert sufficient pressure on the container V in order to effectively hold the container V during rotation. In this configuration, as shown by the arrow R, the rotatable part 3 of the gripper 1 is rotated around the longitudinal axis XX together with the container V.

[0100] Figure 11A shows the gripper 1 in the same configuration as in Figure 10. As can be seen by comparing Figures 11A and 7A, the jaws 4, 5 are not in the same relative position, despite the fact that the piston 26 is also at bottom dead center pmi in the configuration shown in Figures 10 and 11A. Such a difference is counterbalanced by the preloaded spring 17 which tends to extend, as described above, so that the spring 17 in Figure 11A is slightly less extended than the same spring 17 shown in Figure 7A. This feature in fact determines the continuous application of pressure by the jaws 4, 5 to the container V.

[0101] Figure 11B is an enlarged view of the portion indicated within the dotted box in Figure 11A, showing in detail the portion of the gripper 1 where the rod 27 of the piston 26 and the drive shaft 22 of the electric motor remain opposed and separated. As can be seen, there is in fact a gap between the end of the rod 27 and the end of the drive shaft 22, the two shafts not touching each other. Due to the offsets mentioned above, the distance between the drive shaft 22 and the rod 27 is greater in Figure 11B than between the same drive shaft 22 and the rod 27 in Figure 7B.

[0102] Once the container V has been inspected, rotation R is stopped and gripper 1 can be opened to release the container V, as shown in FIG.

[0103] 12A is a perspective view of a gripping hand 600 (end of an arm tool) of an industrial manipulator for moving caps 32 of containers V, for the purpose of screwing and unscrewing the caps 32 on the respective containers V. For simplification, only a gripper 1' according to a different embodiment of the invention in the gripping hand 600 is shown, without the support structure of the gripper 1', electrical and pneumatic connections etc. The body 2 of the gripper 1' is assumed to be held by the support structure of the gripping hand 600.

[0104] As can be seen, the gripper hand 600 comprises 25 grippers 1' arranged side by side in a 5 x 5 matrix arrangement according to the invention. 25 corresponding containers V with caps 32 are placed on the tray 33 and are ready to be uncapped. In other words, the gripper hand 600 has the task of loosening the caps 32 from the containers V located in the tray 33.

[0105] The gripper 1 ′ is vertical, ie its longitudinal axis XX is vertical, with the rotatable part 3 facing towards the tray 33 .

[0106] As can be seen, the gripper 1' is provided with four jaws 34, each arranged crosswise on the rotatable part 3 and sliding in corresponding radial guides of the rotatable part 3. In Fig. 12A, the gripping hand 600 has been moved immediately above the tray 33 so that the cap 32 is within the working radius of the jaws 34, i.e. so that the cap 32 is located between the open jaws 34.

[0107] Such a configuration is more clearly illustrated in FIG. 12B, which is an enlarged view of the area enclosed by the dotted frame in FIG. 12A. Each of the four jaws 34 comprises a finger 35 extending parallel to the longitudinal axis XX of the gripper 1'. Each finger 35 is braked and extendable so that the gripper 1' can be lowered until the finger 35 abuts against the container V. Each finger 35 comprises a spring 36 that exerts a constant thrust to keep the finger 35 in an extended state, and a rubber end 37 intended to rest and apply pressure to the cap 32, in particular to the outer side of the cap 32. As can be seen, the end 37 does not come into contact with the cap 32.

[0108] Fig. 13A is a perspective view of the same gripper hand 600 with the gripper 1' in a different state, specifically with the gripper 1' gripping a corresponding cap 32. The cap 32 of the container V has been removed from the container V and lifted up. Indeed, Fig. 13A shows the gripper 1' with the cap 32 held by its jaws 34.

[0109] FIG. 13B is an enlarged view of the area enclosed within the dotted line box in FIG. 13A, showing gripping end 37 of cap 32 in greater detail.

[0110] An electric actuator of the gripper 1 ′ is used to rotate the rotatable part 3 to screw or unscrew the cap 32 , and a pneumatic actuator of the gripper 1 ′ is used to effect the opening of the jaws 34 .

[0111] In embodiment 1', the electric motor M is actually a gear motor, specifically having a planetary reduction gear.

[0112] In summary, the advantages offered by the gripper 1 are:

[0113] the outer diameter of the body 2 is equal to the outer diameter of the gripper 502, thereby making it completely compatible with grippers 502 of the prior art used in devices 500 for inspecting containers V;

[0114] The gripper 1 comprises both an electric actuator that controls the rotation of the rotatable part 3 and therefore the jaws 4, 5, and a pneumatic actuator that controls the opening of the jaws 4, 5 (considering that the gripper 1 is normally closed), so that the inspection device 500 does not need to be specially equipped with its own actuators.

[0115] - The electric actuator is a single electric motor.

[0116] The structure of the gripper 1 is relatively simple since it does not have concentric shafts (shafts 22 and 27 are on the same axis but are not concentric and do not slide one inside the other), which allows it to be assembled quickly and without excessive costs.

[0117] The gripper 1 makes it possible to eliminate the belt 506, which, due to wear, generates dust that can cause problems in clean rooms.

[0118] Further, the advantages of the structure having the separated shafts 22 and 27 are as follows.

[0119] The gripper 1 does not require a rotary compressed air distributor.

[0120] the gasket 29 does not rotate in the chamber 28 of the pneumatic piston 26 and is therefore durable over time;

[0121] - By pushing against the rear face of the drive shaft 22, the typically small bearings inside the motor M itself (visible in Figures 4 and 5 but not numbered) are not subjected to the force of the spring 17 load.

Claims

1. A gripper (1,1') for an industrial manipulator, comprising: A body (2) having a longitudinal axis (X-X); an electric actuator (M) housed in the main body (2); a rotatable part (3) constrained to said body (2) and rotatable relative to said body (2) about said longitudinal axis (X-X); jaws (4-5, 34) attached to said rotatable part (3) and operable to move towards and away from each other to hold and release an article (V); a control shaft (10) engaged with the jaws (4-5, 34) and coupled to the electric actuator (M), the control shaft (10) being rotatable about the longitudinal axis (X-X) by the electric actuator (M) to rotate the rotatable part (3) and the jaws (4-5, 34) and translatable along the longitudinal axis (X-X) to move the jaws (4-5, 34) toward or away from one another; a pneumatic actuator (26-28) housed in the main body (2), the pneumatic actuator (26-28) including a piston (26) movable between a bottom dead center (pmi) and a top dead center (pms) in response to a pressure applied by compressed air supplied to the gripper (1) by an external means (509); the piston (26) is configured to impart a thrust force to the control shaft (10) for at least a portion of the movement of the piston (26); movement of the piston (26) between the bottom dead centre (pmi) and the top dead centre (pms) causes the control shaft (10) to translate along the longitudinal axis (X-X) and actuate the jaws (4-5, 34); said electric actuator (M) and said pneumatic actuators (26-28) are configured to remain separate and not interact with each other while said electric actuator (M) is in operation; The electric actuator (M) and the pneumatic actuators (26-28) are configured to remain integrated while the pneumatic actuators (26-28) are in operation. A gripper (1,1').

2. The gripper (1, 1') according to claim 1, wherein the electric actuator (M) is an electric motor or a gear motor having a drive shaft (22) rotatable about the longitudinal axis (X-X), the rotation of the drive shaft (22) being integrated with the control shaft (10).

3. 3. Gripper (1, 1') according to claim 2, wherein the control shaft (10) and the drive shaft (22) are butt-connected in a non-telescopic manner.

4. The gripper (1, 1') according to any one of claims 1 to 3, characterized in that the electric actuator is an electric motor or gear motor (M) slidably accommodated in the main body (2) and allowed to translate between a bottom dead center (pmi) and a top dead center (pms) along the longitudinal axis (X-X), the bottom dead center of the electric motor or gear motor (M) corresponding to one of the mutual positions of the jaws (4-5, 34) selected from an approaching position and a separating position, and the top dead center of the electric motor or gear motor (M) corresponding to the other of the mutual positions of the jaws (4-5, 34) selected from the approaching position and the separating position.

5. The gripper (1,1') according to claim 4, comprising an elastic element (17) operatively interposed between the body (2) and the electric actuator (M) for opposing the translation of the electric motor (M) along the longitudinal axis (X-X).

6. The gripper (1, 1') according to claim 5, wherein the elastic element is a spring (17) housed in the body (2) between the rotatable part (3) and the electric actuator (M), the spring (17) being preloaded and always exerting a thrust on the electric actuator (M) in a direction that moves the electric actuator (M) to a bottom dead center (pmi) corresponding to the jaws (4-5, 34) approaching each other.

7. Gripper (1, 1') according to claim 6, wherein said spring (17) is arranged coaxially with said longitudinal axis (XX).

8. The gripper (1, 1') according to any one of claims 5 to 7, comprising a sleeve (18) constrained to the electric actuator (M) and arranged coaxially with the drive shaft (22) and the control shaft (10) and with the elastic element (17), the sleeve (18) being in contact with an end of the body (2) of the gripper (1) when the electric actuator (M) is at top dead centre (pms), thus defining a limit stop.

9. 9. The gripper (1, 1') according to claim 8, comprising a plurality of radial pins (19) each inserted into a radial through hole (20) drilled in a side wall of the body (2) of the gripper (1), the sleeve (18) comprising an elongated slot (21) in the direction of the longitudinal axis for each of the radial pins (19), the radial pins (19) engaging with the corresponding elongated slots (21), and an axial limit stop of the sleeve (18) corresponding to the radial pin (19) abutting against one of the two ends of the corresponding elongated slot (21).

10. 10. The gripper (1,1') according to any one of claims 1 to 9, wherein the jaws (4-5,34) are slidably received in corresponding guides (6) of the rotatable part (3), the gripper (1) comprises for each of the jaws (4-5,34) a lever (4',5') pivoted on the rotatable part (3) to oscillate in a plane parallel to the longitudinal axis (X-X), and an end (10') of the control shaft (10) is slidably inserted in the rotatable part (3) and engages with the lever (4',5'), each angular position of the lever (4',5') uniquely corresponding to an axial position of the control shaft (10).

11. 11. The gripper (1,1') according to any one of claims 1 to 10, comprising a pin (14) inserted radially through the control shaft (10), the pin (14) engaging with a slot (15) of the rotatable part (3) to transmit a rotation about the longitudinal axis (X-X), the pin (14) being slidable in the slot (15) in the direction of the longitudinal axis, the axial extent of the slot (15) being equal to or greater than the axial movement of the control shaft (10), or at least a part of the control shaft (10) having a non-circular cross section engaging with a corresponding complementary guide of the rotatable part (3).

12. The gripper (1, 1') according to any one of claims 1 to 11, wherein an end (10') of the control shaft (10) protrudes from the body (2) of the gripper (1) and engages with the rotatable part (3), and the control shaft (10) is telescopically movable between a retracted position and an extended position, the retracted position and the extended position corresponding to a state selected from a state in which the jaws (4-5, 34) are close to each other and a state in which the jaws (4-5, 34) are spaced apart from each other, respectively.

13. The gripper (1, 1') according to any one of claims 1 to 12, wherein the piston (26) is provided with a thrust portion or rod (27), and at the bottom dead center (pmi) of the piston (26), the rod (27) is separated from the electric actuator (M) and does not provide thrust, and at the top dead center (pms) of the piston (26), the rod (27) abuts against the electric actuator (M) and provides axial thrust to the electric actuator (M).

14. The gripper (1, 1') of claim 13, wherein the electric actuator (M) is an electric motor or a gear motor having a drive shaft (22) rotatable around the longitudinal axis (X-X), the drive shaft (22) passing through the electric motor (M), and the rod (27) of the piston (26) is abuttable against an end of the drive shaft (22).

15. 15. Gripper (1,1') according to claim 14, wherein at the bottom dead center (pmi) of the piston (26), the rod (27) is separated from the drive shaft (22) and is de-rotated therefrom.

16. The gripper (1, 1') according to any one of claims 13 to 15, comprising an elastic element (30) preloaded to oppose axial displacement of the piston (26), the elastic element (30) always exerting a thrust on the piston (26) in a direction moving the piston (26) away from the electric actuator (M).