Electric grippers for industrial manipulators

Abstract

A gripper for industrial manipulators, in particular optical inspection devices for inspecting transparent or translucent containers, is described. The gripper comprises a body having a longitudinal axis, an upper part bound to the body and rotatable about the longitudinal axis, an actuator for imparting rotation to the upper part, and jaws attached to the upper part and movable toward and away from each other to lift and release objects. The rotation of the upper part and the actuation of the jaws are controlled by the same electric motor, i.e. a single motor, housed in the gripper itself, and not by means external to the gripper, e.g. a drive belt of an apparatus to which the gripper is attached. 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 that is coaxial with the longitudinal axis and connected to the upper part. The assembly formed by the electric motor and the drive shaft is translatable along the longitudinal axis to impart a movement of the jaws toward and away from each other to open and close the gripper.

Description

Technical Field

[0001] The present invention relates to an industrial manipulator, particularly an electric gripper for a container inspection device in the pharmaceutical industry.

Background Art

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

[0003] Grippers for industrial manipulators generally include a body and two or more jaws or gripper fingers attached to the body. The jaws can move away from and towards each other between an open position, i.e., a release position, where no force is applied to the article to be manipulated, and a closed position, i.e., a gripping position, where sufficient force is applied to the article to be manipulated to prevent accidental release of the part being held.

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

[0005] Grippers used in inspection devices for quality control of containers in the pharmaceutical industry are a special case. These inspection devices are optical inspection devices that inspect transparent or translucent vials, bottles, and containers arranged along a production line, and perform 100% quality control of the manufactured containers from the viewpoints of the integrity of the containers and their respective lids, as well as the quantity and purity of the contents. In these inspection devices, a plurality of grippers are arranged in a row or circularly according to a carousel configuration, adjacent to each other. Each gripper lifts a container, transports the container in front of a camera that takes one or more images of the container itself, and the images are processed by a computer to detect any abnormalities. Strobe light is often used to take the images.

[0006] In many cases, this type of inspection device has grippers arranged on a carousel structure. In addition to the conventional opening and closing motion of the grippers, the grippers are required to rotate around their own longitudinal axis to temporarily generate vortices within the container of the liquid being inspected. This longitudinal axis also corresponds to the axis around which the piece is gripped. Images of the container and vortices captured by the inspection device make it possible to detect abnormalities such as impurities in the contents or excesses or deficiencies in the liquid volume.

[0007] Since the grippers are adjacent to each other and the available space is minimal, grippers without actuators are preferable in the inspection apparatus described above, precisely because actuators negatively affect the dimensions of each gripper and, ultimately, the dimensions of the entire inspection apparatus.

[0008] Generally, a gripper attached to an inspection device has a stem slidably mounted on a dedicated seat on the gripper body, which is movable along its longitudinal axis between distal and proximal positions in response to a force applied by a cam controlled by another component of the inspection device. Specifically, one cam is provided for each gripper. The position of the stem relative to the body uniquely determines the position of the gripper jaws, i.e., the opening and closing of the gripper jaws is mechanically controlled. In other words, gripping and releasing a container is controlled by a cam acting on the sliding stem of each gripper, and the stem is returned to its initial position with the jaws closed by an appropriate spring or other biasing means.

[0009] The rotation of the grippers around their longitudinal axis is achieved by attaching the grippers to the carousel structure of the inspection device with rotary couplings, placing electric motors in the carousel structure, and using drive belts to connect one or more grippers to the same electric motors. The rotation of the electric motor pulleys is transmitted by the belts to the bodies of each gripper, causing the grippers to rotate around their longitudinal axis. The rotational speed is typically 400-800 rpm, but can reach 3000 rpm.

[0010] Ultimately, the grippers used in container inspection devices differ from conventional grippers in that they do not have their own actuators inserted into the gripper body to operate the jaws, and their operation relies on cams and electric motors (connected by belts) that are not part of the gripper and are located in the inspection device, particularly in a carousel structure.

[0011] An example of the inspection equipment can be seen in the video accessible at the following link: https: / / youtu.be / xC2ed0Tu2NU.

[0012] IT202019000002871, filed in the name of the present applicant on August 27, 2019, describes an industrial manipulator, a gripper for an optical inspection device for inspecting transparent or translucent containers, which gripper, - A main body having a longitudinal axis and capable of being attached to an external structure, - An upper portion that is constrained to the main body and rotatable about the longitudinal axis relative to the main body, - Means for giving rotation to the upper portion around the longitudinal axis, - Jaws attached to the upper portion, which are movable relative to the upper portion so as to move closer to and further apart from each other in order to lift or release objects such as containers, - The system includes means for controlling the opening and closing operation of the jaws.

[0013] The rotation of the upper portion is not provided by an external belt or other means of the gripper, but by an actuator housed within the gripper itself, specifically an electric motor. More specifically, the gripper includes a hollow drive shaft positioned along the gripper's longitudinal axis. The hollow drive shaft is connected to the upper member, and the rotation imparted to the drive shaft by the electric motor, with respect to the longitudinal axis, is transmitted to the jaws. Thus, the longitudinal axis of the gripper is also the axis of rotation of the jaws. The jaw control rod is retractable, i.e., slidable, within the drive shaft and precisely has the function of opening the jaws.

[0014] The displacement of the control rod relative to the drive shaft is provided by an external actuator of the gripper, such as a cam on the vial inspection device to which the gripper is attached. When the force applied to the control rod by the cam is removed, an elastic member causes the jaws to automatically return and close.

[0015] Filing on May 15, 2009, under the name of Pharmamech, patent application IT102009901732640 (IT PR20 090 040) describes and claims two embodiments of a gripper configured for manipulating test tubes or vials in a machine specifically for quality control. Referring to the relevant drawings, both embodiments include an electric motor and actuator arranged coaxially with the axis of the gripper, which control a coaxially arranged outer shaft 8 and control rod 10. The outer shaft 8 is hollow, and the control rod 10 is inserted into it and slides in a nested manner. In the first embodiment, the outer shaft 8 is a drive shaft rotated by the actuator when the gripper is closed, rotating the test tube or vial to enable inspection using an optical system. When the gripper is stationary, the control rod 10 is driven, i.e., translated relative to the drive shaft 8 to open the jaws and release the test tube / vial. In the second embodiment, the actuator is shown as a “rotary actuator device” 14 and acts only on a control rod 10 that can receive both translational motion relative to the drive shaft 8 for opening and closing the gripper and rotational motion for rotating the test tube / vial, while the drive shaft 8 remains idle.

[0016] CN1111353 describes a gripper in which opening and closing is controlled by an axial stem, while the axial stem is controlled by an offset actuator and rotation is provided by a belt and pulley system.

[0017] US6544799 describes a gripper system having a longitudinal stem for opening and closing jaws, but this gripper system does not rotate the gripper.

[0018] US20080085507 describes a rotary gripper having three jaws, where the opening and closing of the jaws is controlled by the same axial motor that controls the rotation of the gripper, but the movement of the jaws is achieved by using spur gears to rotate the jaws around an axis parallel to the axis of the gripper.

[0019] US20090179445 describes a gripper with two motors, the first rotary motor which rotates the jaws by imparting rotation to a hollow drive shaft indicated as 20 in the figure, and the second linear motor, indicated as 22 in the figure and housed in the drive shaft 20, which acts as a retractable push rod that opens and closes the jaws.

[0020] DE10120939A describes a gripper having two parallel jaws and an electric actuator. The upper portion of the gripper housing the jaws does not rotate relative to the gripper body and is fixed to the gripper body. The electric actuator, fixed and housed within the gripper body, has a drive shaft capable of receiving translational motion along the longitudinal axis of the gripper in order to provide opening and closing motion for the jaws.

[0021] Other publicly known solutions are disclosed in WO2015 / 070839 and US4607873.

[0022] The applicant is confident that these described inspection devices can be improved and made simpler in structure. [Overview of the project]

[0023] The object of the present invention is to provide a gripper for industrial manipulators, which is electrically operated, i.e., has a unique electric motor for giving rotation to the upper portion, and has a simpler structure than known solutions.

[0024] Therefore, the present invention relates to the gripper described in claim 1.

[0025] That is, the present invention relates to a gripper for an industrial manipulator, particularly for an optical inspection device for inspecting transparent or translucent containers, and the gripper is a main body having a longitudinal axis and being attachable to an external device, particularly an optical inspection device, and an upper portion constrained to the main body and rotatable about the longitudinal axis with respect to the main body, and a jaw attached to the upper portion and movable with respect to the upper portion so as to approach and separate from each other to lift and release an object, particularly a container to be inspected, and a single electric motor constrained to the main body, and an actuator including a drive shaft provided coaxially with the longitudinal axis to connect the electric motor to the upper portion and the jaw. The electric motor and the main body of the gripper are separate components, which means that the fixing of the gripper to the device is performed on the main body rather than on the motor.

[0026] The drive shaft has a dual function of imparting rotation to the jaw and opening and closing the jaw by approaching and separating the jaw from each other.

[0027] Regarding the rotation of the jaw about the longitudinal axis, the drive shaft is rotated about the longitudinal axis by the electric motor, and as a result, the upper portion is rotated to cause the rotation of the jaw.

[0028] Regarding the movement of the jaw approaching and separating from each other, the assembly formed by the electric motor and the drive shaft is displaceable along the longitudinal axis with respect to the main body in response to a force applied by means external to the gripper, specifically, a force applied by an inspection device, such as a cam.

[0029] With such a configuration, in the carousel structure, there is no need to arrange an electric motor and a drive belt for connecting a plurality of grippers, so that a simpler inspection device can be constructed more compactly without using a gripper drive belt.

[0030] Furthermore, by assembling multiple grippers according to the present invention into a manipulator or (container) inspection device, it is possible to selectively operate each gripper, that is, to rotate one gripper independently of the others, which is not possible when an external electric motor is shared among two or more grippers.

[0031] The proposed solution eliminates the need for a belt drive system, as was conventionally used to rotate the upper part of the gripper and jaws, thus facilitating the replacement of the gripper in the manipulator or (container) inspection device.

[0032] Furthermore, since belts wear down over time, releasing particles that adhere to the manipulator or inspection device, the absence of a drive belt allows for a better level of cleanliness to be maintained.

[0033] The gripper proposed herein has an extremely simple structure and can be assembled and maintained at low cost. The function of rotating the jaws is assigned to an electric motor, as is also provided in other solutions by known technology, but the movement of the jaws moving toward / apart from each other does not require a second actuator, i.e., a dedicated motor. This movement is actually caused by the same electric motor that controls the rotation. The electric motor is axially movable relative to the body of the gripper in order to give the drive shaft, which controls the displacement of the jaws, the corresponding movement. The axial movement of the electric motor is provided by the inspection device to which the gripper is mounted, for example, a dedicated cam pusher element. This makes it possible to minimize the dimensions of the gripper and thus maximize the number of grippers that can be mounted on the carousel of the inspection device.

[0034] Unlike some known solutions, the gripper proposed herein has a single drive shaft instead of two coaxial shafts, one of which provides rotation to the jaws and the other which controls the opening of the jaws. In the gripper according to the present invention, the single drive shaft performs both functions.

[0035] The gripper has a lower portion that is constrained to the main body on the opposite side of the upper portion, and the electric motor is preferably housed in the lower portion. The drive shaft passes through the main body and is slidably housed in a corresponding seat of the main body. This configuration allows the gripper to be positioned in the inspection device such that, on the opposite side of the jaws, the cam pusher element acts on the base of the electric motor.

[0036] The radial dimension of the electric motor is preferably less than or equal to the radial dimension of the main body, and in particular, the gripper is preferably formed with a main body that has the largest diameter among all the components of the gripper.

[0037] In a preferred embodiment, the gripper body is at least partially hollow, and the electric motor is constrained to the body by a retractable or piston-like coupling and is translatable between a retracted drive shaft and a maximum insertion position into the body corresponding to a first position, e.g., a spaced-out / open position for the jaws, and a minimum insertion position into the body corresponding to a retracted drive shaft and a second position, e.g., a close-up / closed position for the jaws, which can also be defined as a partially withdrawn position. In such a configuration, the electric motor and the gripper body essentially constitute a cylinder-piston coupling.

[0038] The drive shaft preferably has a wedge-shaped portion, also called a slider, at its upper end. The jaws are capable of moving radially with respect to the longitudinal axis, and each has an inclined surface, which remains in contact with the wedge-shaped portion of the drive shaft and is intended to slide in response to the axial displacement of the drive shaft. In this way, that is, through the inclined surface coupling, the axial displacement of the drive shaft causes the radial displacement of the jaws.

[0039] The jaw configuration described above is not the only possible. In fact, grippers can also be formed by employing either jaws that can move between close and far positions, or jaws that rotate between two positions, following configurations known in the field of grippers for industrial automation.

[0040] For example, the jaws may be cams that rotate between open and closed positions due to thrust applied by a corresponding thrust element driven by an electric motor. In other words, the movement of the jaws may involve angular changes and is not necessarily linear.

[0041] Alternatively, the gripper can be formed using a lever mechanism such as a rack-and-pinion mechanism for linearly moving the jaws, or a four-bar linkage mechanism actuated by an electric motor.

[0042] The gripper preferably includes an elastic element to counteract the displacement of the electric motor relative to the body, so that the jaws automatically return to one of the manufacturer's selectable positions (separated, approached). Typically, the preloaded elastic element preferably constantly applies a force that pushes the jaws to close in contact with the part being lifted. For example, if the position where the gripper is withdrawn from the body (or vice versa) corresponds to the position where the jaws are brought close together and closed in contact with the part, the gripper may be formed with a spring that constantly presses the electric motor to this position.

[0043] To minimize dimensions and simplify the structure, it is preferable to use a helical spring as the elastic element and house this helical spring inside a main bushing that fits onto the drive shaft and also functions as a guide for the drive shaft. Therefore, in this configuration, the drive shaft, helical spring, and guide bushing are coaxial.

[0044] In a preferred embodiment, the drive shaft is hollow and allows for the insertion of an optical fiber or wire to supply power to the accessories. The drive shaft passes through the gripper and has open ends, with a lower first opening usable from the base of an electric motor and an upper opening usable in the upper portion between the jaws. [Brief explanation of the drawing]

[0045] Further features and advantages of the present invention should become more apparent by examining the following detailed description of preferred but non-exclusive embodiments, which are shown for illustrative purposes only and without limitation with reference to the accompanying drawings.

[0046] [Figure 1] Figure 1 is an exploded elevation view of the gripper according to the present invention. [Figure 2] Figure 2 is a perpendicular cross-sectional view of the gripper shown in Figure 1, viewed in a plane containing the longitudinal axis. [Figure 3] Figure 3 is a perspective view of the gripper shown in Figure 1. [Figure 4] Figure 4 is a vertical cross-sectional view of the gripper shown in Figure 1, with the jaws close together, i.e., closed. [Figure 5] Figure 5 is a vertical cross-sectional view of the gripper shown in Figure 1, with the jaws separated, i.e., in the open position. [Figure 6] Figure 6 is an oblique circumferential cross-sectional view of two grippers according to the present invention, attached to a carousel structure of a container inspection device. [Figure 7] Figure 7 is a perspective view of two grippers according to the present invention, attached to a carousel structure of a container inspection device. [Figure 8] Figure 8 is a partial elevation cross-sectional view showing a portion of a gripper according to an alternative embodiment of the present invention. [Figure 9] Figure 9 is an elevation cross-sectional view showing a part of a gripper according to a further embodiment of the present invention. [Modes for carrying out the invention]

[0047] Figures 1 to 5 show a first embodiment of a gripper for an industrial manipulator according to the present invention.

[0048] The gripper 1 comprises a body 2 that can be attached to an external structure such as a plate, which is part of a carousel structure in an inspection device for transparent or translucent containers commonly used in the pharmaceutical industry. In the illustrated embodiment, the body 2 comprises two components, namely a bush 2' and a component 2'' that can be attached to an external structure.

[0049] The gripper 1 comprises an upper portion 4 formed by two substantially cylindrical members 4', 4'' and a lower portion 5 positioned on the opposite side from the main body 2.

[0050] Generally, a gripper may have multiple jaws, such as three. In the illustrated embodiment 1, the upper portion 4 has two jaws identified by reference numerals 6 and 7, which are movable within a suitable seat of member 4' (as can be seen in Figure 1). Specifically, jaws 6 and 7 are able to move apart from and closer to each other in order to grip and release the container being inspected.

[0051] As those skilled in the art will understand, the terms upper and lower, which describe parts of the gripper 1, are based on the orientation of the gripper 1 in the accompanying diagram. However, during use of the gripper 1, the upper portion 4 may actually be facing downwards, meaning that the gripper 1 may be used in the opposite direction to that shown in the accompanying diagram.

[0052] More specifically, jaws 6 and 7 are capable of moving radially between a position proximal to the longitudinal axis XX of the gripper 1, corresponding to the part gripping position, and a position distal to the longitudinal axis XX, corresponding to the part release position.

[0053] As will be explained in more detail, the upper portion 4 is rotatable relative to the main body 2 around the longitudinal axis XX. Therefore, the upper portion 4 is supported by a bearing 8.

[0054] The gripper 1 further comprises a single electric motor 15, which, in the illustrated embodiment, is constrained to the lower portion 5. The electric motor 15 comprises its own shaft 15' positioned on the longitudinal axis XX. The gripper comprises a drive shaft 14 connected to the shaft 15' of the electric motor 15, forming a single drive shaft 14 that runs through the entire gripper 1.

[0055] The drive shaft 14 is formed by joining components 14', 14'', and 14'''' (Figure 1), with the first component 14' being wedge-shaped.

[0056] The jaws 6 and 7 are operated by a drive shaft 14 housed within the seat portion 2' of the gripper body 2, which slides along the longitudinal axis XX between a distal or extended position corresponding to jaws 6 and 7 in a close position, i.e., the closed position, and a proximal or retracted position corresponding to jaws 6 and 7 in a far-away position, i.e., the open position.

[0057] More specifically, the drive shaft 14 is biased by an elastic means 10, for example, a spring 10 shown in the figure, which is fitted onto the drive shaft 14 and inserted into a bush 2' that defines a seat where the drive shaft 14 is slidably housed, so that the drive shaft 14 can extend and retract in a nesting manner relative to the body 2 of the gripper 1. When the force moving the electric motor 15 and the drive shaft 14 toward the jaws 6 and 7 relative to the body 2 is removed, the drive shaft 14 is automatically returned to its initial position by the elastic member 10.

[0058] The upper end of the drive shaft 14 is wedge-shaped, indicated by reference numeral 14', and is a member inserted between the jaws 6 and 7, meaning it has a wedge structure that functions as a slider due to its inclined surface. This member 14' is inserted between the jaws 6 and 7 and is intended to spread them apart, that is, to open and separate the jaws 6 and 7 to release a part that is already being lifted, for example. For this purpose, the jaws 6 and 7 are provided with corresponding inclined surfaces 6' and 7' (Figure 1) that are intended to contact the member 14' of the drive shaft 14 and move along the member 14' (inclined surface coupling).

[0059] The movement of the jaws 6 and 7 toward and apart from each other, i.e., opening and closing, is caused by translating the drive shaft 14 toward the jaws 6 and 7 themselves, so that the wedge-shaped end 14' of the drive shaft 14 is inserted between the jaws 6 and 7, spreading them apart and, for example, moving the jaws 6 and 7 to the part release position.

[0060] The thrust to the drive shaft 14 is applied by an electric motor 15, which, as will be described later, is movable axially relative to the body 2 of the gripper 1. The electric motor 15 is then subjected to a force by an external means to displace axially along the longitudinal axis XX. For example, in a container inspection device, the external means is a cam pusher of the inspection device, which applies thrust to the electric motor 15 when needed, as shown by the upward and branching arrows in Figure 5. The electric motor 15 is partially pushed inward into the gripper body 2, and thus a displacement H (Figures 4 and 5) of preferably in the range of 5 to 15 mm, for example, 8 mm. In the illustrated embodiment, the axial displacement H of the electric motor 15 corresponds to the axial movement of the drive shaft 14, because these two components move together on the longitudinal axis XX.

[0061] Figure 5 shows a vertical cross-section of the gripper 1 with the jaws 6 and 7 in the open position, where the motor 15 is in its maximum insertion position into the body 2, which means that the amount of movement H is at its maximum, and the drive shaft 14 is in a fully retracted position corresponding to the wedge-shaped member 14' inserted between the opened jaws 6 and 7.

[0062] Figure 4 shows a vertical cross-section of the gripper 1 with jaws 6 and 7 in the closed position. The motor 15 is in its minimum insertion position into the body 2, which means the amount of movement H is zero. The drive shaft 14 is in its fully extended position corresponding to the wedge-shaped portion 14' that is not inserted between jaws 6 and 7. At this time, jaws 6 and 7 remain close together in their proximal position, i.e., closed. More specifically, when the force applied by the external pusher member is removed, the elastic member 10 returns the drive shaft 14 to its initial position, i.e., the wedge-shaped end 14' retracts, and jaws 6 and 7 return to their proximal position, the part-gripping position in the illustrated example.

[0063] The gripper may also be equipped with an elastic member (not shown) for closing the jaws 6 and 7. The elastic member, such as a spring or annular gasket, engages with the two jaws 6 and 7 and constantly applies a force to the jaws 6 and 7 that tries to bring them closer together, that is, a force that tries to close the jaws 6 and 7.

[0064] Jaws 6 and 7 are capable of rotational motion around the longitudinal axis XX, in addition to the radial motion described above for gripping and releasing parts. Such motion is directly provided by the drive shaft 14, which is rotated by the electric motor 15, thereby rotating the upper portion 14 relative to the gripper body 2. In practice, the wedge-shaped portion 14' of the drive shaft 14 is not rotatable within the component 4' of the upper portion 4 due to its shape.

[0065] In the gripper 1 shown in the figure, the upper portion 4 is supported by the main body 2 by a ball bearing 8.

[0066] Consequently, the operation of the electric motor 15 causes the upper portion 4 of the gripper 1 to rotate clockwise or counterclockwise around the longitudinal axis XX. In a container inspection device, this condition occurs when the jaws 6 and 7 are in the part gripping position, that is, when the jaws are close together.

[0067] An encoder can be provided with the electric motor 15. In this case, the encoder allows monitoring of the rotational speed of the shaft 15', enabling feedback control of this rotational speed. Furthermore, the encoder allows detection of the angular position of the upper part 4 of the gripper 1 at any time, making it possible to align the jaws 6 and 7 with the part to be lifted or released, or other parts of the inspection device, as needed.

[0068] Now, considering in more detail the coupling between the electric motor 15 and the gripper body 2, this coupling can be defined as a cylinder-piston type. Referring to the figure, it can be seen that the body 2 is indeed hollow and, more precisely, has an (inverted) socket shape. The electric motor 15 has a cylindrical portion 15''' at the top of the motor that defines a skirt facing the body 2 (these two components are screwed together). The skirt member 15''' has a slot 19 that penetrates its side, and the slot 19 engages with a pin 20 which is integrated with the body 2, in particular the socket-shaped member 2''', defining the limit stop boundary of the electric motor 15.

[0069] As shown in Figures 4 and 5, the skirt member 15'' of the electric motor 15 is slidably inserted into the socket-shaped member 2''' of the main body 2, thereby forming a piston-like or cylinder-piston coupling. The drive shaft 14 is coaxially inserted into the bush 2', and the spring 10 is fitted onto the drive shaft 14. The pin 20 defines limit stops in two directions of axial displacement of the electric motor 15.

[0070] As shown in the figure, it is generally advantageous to place the electric motor 15 inside the gripper 1, especially when the radial dimension of the motor 15 does not exceed the radial dimension of the rest of the gripper 1. In fact, in the illustrated example, since the lower portion 5 has the same outer diameter as the gripper body 2, it is generally preferable that the diameter of the lower portion 5 in which the electric motor 15 is housed is less than or equal to the diameter of the gripper body 2.

[0071] The drive shaft 14 is preferably hollow and extends between a lower opening 16 at the base 18 of the electric motor 15 and an upper opening 17 at the upper portion 4 between the jaws 6 and 7. Where required in a particular application, a fiber optic cable or a wire for supplying power to an accessory of the gripper 1, or optionally for supplying compressed air or air suction, can be inserted through the drive shaft.

[0072] It is useful to note the absence of a second coaxial shaft within the drive shaft 14, as is provided in some solutions using known technologies. This significantly simplifies the structure and leaves space for the aforementioned accessories.

[0073] Referring particularly to Figures 6 and 7, possible methods for assembling two grippers 1 to the same structure 21 of a container inspection device (not shown) are illustrated. Structure 21 is part of a larger carousel structure. The grippers 1 are shown side by side, with their jaws 6,7 oriented perpendicularly to each other; that is, with respect to structure 21, the right-hand gripper 1 has jaws 6,7 oriented tangentially, and the left-hand gripper 1 has jaws 6,7 oriented radially.

[0074] As described above, the gripper 1 is locked to the structure 21 at member 2'' of the main body 2, and therefore remains stationary relative to the structure 21. The upper portion 4 of the gripper 1, and together with it the jaws 6 and 7, are rotatable around the longitudinal axis XX by the operation of the electric motor 15 of each gripper 1, i.e., without using a drive belt connected to the inspection device.

[0075] In the above configuration, it is clear that the electric motors 15 of each gripper 1 can be operated selectively and independently of each other. Therefore, the jaws 6 and 7 of gripper 1 can rotate independently of the jaws 6 and 7 of adjacent grippers 1, but this does not apply to existing solutions in which an external motor operates multiple grippers via a corresponding drive belt, and simultaneous rotation of all grippers connected to that motor is achieved by operating a common motor.

[0076] As described above, the arrangement of the electric motor 15 within the gripper 1 is advantageous, in particular, when the radial dimension of the electric motor 15 does not exceed the radial dimension of the rest of the gripper 1, as shown in the figure. In fact, in the illustrated example, the lower portion 5 has the same outer diameter as the main body 2 of the gripper.

[0077] In particular, since the electric motor 15 is located within the radial dimension of the gripper 1, the minimum moment of inertia of the electric motor 15 with respect to the longitudinal axis XX is achieved, which allows the changes in acceleration and deceleration of the electric motor 15 to be shorter than those possible with conventional solutions.

[0078] The operation cycle of each gripper 1 can be described as follows:

[0079] - By applying an upward force to the electric motor 15 via a cam pusher element (not shown) constrained by the structure 21, the translational motion of the electric motor 15 is transmitted to the drive shaft 14. - The jaws 6 and 7 are extended in accordance with the thrust applied by the wedge-shaped portion (slider) 14' and their respective inclined surfaces. - When the thrust applied to the electric motor 15 is removed, the spring 10 returns the electric motor 15 to its initial position, which was removed from the main body 2, and the jaws 6 and 7 are returned to their initial closed position. - The rotation of the upper part 4, and the resulting rotation of the jaws 6 and 7, is provided by an electric motor 15 using a drive shaft 14. This causes the upper part 4 to rotate via the wedge-shaped part 14', while the main body 2 and bush 2' remain stationary. - To prevent relative rotation between the electric motor 15 and the main body 2, a pin 20 (rotation prevention) is used, which is constrained by a member 2''' of the main body 2 and inserted into a slot 19 of a member 15''' of the electric motor 15.

[0080] Figure 8 is an elevation portion vertical section view of part 4 of another embodiment of the gripper according to the present invention, in which jaws 6 and 7 are moved by a rack and pinion mechanism, the whole of which is shown as reference no. 23.

[0081] The drive shaft 14 has a toothed portion 24 that meshes with a gear 25 that rotates around a rotation axis 26 which is not coplane with the longitudinal axis XX. The gear 25 then meshes with a rack 27 formed on the lower surface of the jaw 7. The jaw 6 has the same mechanism.

[0082] Figure 9 is a vertical cross-sectional view of the upper portion 4 of the gripper according to a further embodiment of the present invention, viewed in a plane containing the longitudinal axis XX. The jaws 6 and 7 are connected to the drive shaft 14 by levers 28 pivotally supported on the drive shaft 14 and jaws 6 and 7, respectively, on a rotation axis that is not coplane with the longitudinal axis XX. As shown in the figure, the levers 28 intersect each other.

[0083] Instead of the linear motion of jaws 6 and 7, gripper 1 can be formed with jaws that can rotate between an open position and a closed position in a plane perpendicular to the longitudinal axis XX.

Claims

1. A gripper (1) for an industrial manipulator, particularly for an optical inspection device for inspecting transparent or translucent containers, A main body (2) having a longitudinal axis (X-X) and capable of being attached to an external device, The upper portion (4) is constrained to the main body (2) and is rotatable relative to the main body (2) around the longitudinal axis (X-X), Jaws (6, 7) are attached to the upper portion (4) and are capable of moving toward and away from each other relative to the upper portion (4) in order to lift or release an object, particularly a container. The system comprises a single electric motor (15) constrained to the main body (2), and an actuator (12) provided coaxially with the longitudinal axis (X-X) and having a drive shaft (14) that connects the electric motor (15) to the upper portion (4) and the jaws (6, 7), The drive shaft (14) is rotated by the electric motor (15) around the longitudinal axis (X-X), and as a result rotates the upper portion (4), The assembly formed by the electric motor (15) and the drive shaft (14) is displaceable relative to the main body (2) along the longitudinal axis (X-X) in response to a force applied by external means of the gripper (1) in order to move the jaws (6, 7) closer together or further apart from each other. Grippa (1).

2. The gripper (1) according to claim 1, comprising a lower portion (5) constrained to the main body (2) on the opposite side from the upper portion (4), the electric motor (15) being housed in the lower portion (5), and the drive shaft (14) passing through the main body (2) and being slidably housed in a corresponding seat portion (2''') of the main body (2).

3. The gripper (1) according to any one of claims 1 to 2, wherein the radial dimension of the electric motor (15) is less than or equal to the radial dimension of the main body (2).

4. The electric motor (15) comprises a shaft (15') of the electric motor coupled to the drive shaft (14), the gripper (1) according to any one of claims 1 to 3.

5. The gripper (1) according to any one of claims 1 to 4, wherein the body (2) is at least partially hollow, and the electric motor (15) is constrained to the body (2) by an extendable coupling and is movable between a maximum insertion position into the body (2) corresponding to a retracted drive shaft (14) and jaws (6, 7) in a first position and a minimum insertion position into the body (2) corresponding to a withdrawn drive shaft (14) and jaws (6, 7) in a second position.

6. The gripper (1) according to any one of claims 1 to 5, wherein the drive shaft (14) has a wedge-shaped portion (14') at its upper end which is also set to function as a slider, and the jaws (6, 7) are capable of moving radially with respect to the longitudinal axis (X-X), each having an inclined surface (6', 7'), and the inclined surfaces (6', 7') are intended to slide against the wedge-shaped portion (14') in response to the axial displacement of the drive shaft (14), so that the axial displacement of the drive shaft (14) causes the radial displacement of the jaws (6, 7).

7. The gripper (1) according to any one of claims 1 to 6, comprising an elastic element (10) that resists the displacement of the electric motor (15) relative to the main body (2).

8. The gripper (1) according to claim 7, wherein the elastic element (10) is a helical spring, the helical spring is fitted onto the drive shaft (14) and housed inside a bush (2''') of the main body (2) that guides the drive shaft (14), and the drive shaft (14), the helical spring (10), and the bush (2''') are coaxial.

9. The gripper (1) according to any one of claims 7 and 8, wherein the elastic element (10) is preloaded and constantly applies force to the electric motor (15) in a direction corresponding to the closing motion of the jaws (6, 7) so as to contact the part being lifted.

10. The amount of movement (H) of the electric motor (15) relative to the main body (2) is 5 mm to 15 mm, preferably 8 mm, according to any one of claims 1 to 9, gripper (1).

11. The gripper (1) according to any one of claims 1 to 10, wherein the drive shaft (14) is hollow, penetrates the gripper (1), and has a first lower opening (16) accessible from the base (18) of the electric motor (15) and an upper opening (17) accessible in the upper portion (4) between the jaws (5 to 7).

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