GRAPPLING DEVICE

Abstract

A grasping device for an object comprising a platform (10) with longitudinal axis (X) and six fingers (13, 14) articulated for rotation on the platform (10), and grasping means carried by each of the free ends of the fingers (13, 14), the at least three fingers (13, 14) being regularly articulated angularly around the longitudinal axis (X), each finger (13, 14) comprising a double parallelogram linkage including a first parallelogram (P1) articulated on the platform (10) about an axis orthogonal to the longitudinal axis (X), a second parallelogram (P2) being articulated on the first parallelogram (P1), and a set of gears between the first parallelogram (P1) and the second parallelogram (P2), such that the movement in one direction of rotation of the first parallelogram (P1) imposes a movement in the opposite direction of rotation of the second parallelogram. (P2),and an actuator (A1) carried by the platform and configured to move all the fingers (13, 14) simultaneously. [Fig.2]

Description

Title of the invention: GRIPPING DEVICE TECHNICAL FIELD AND PREVIOUS ART

[0001] The present invention relates to a gripping device intended for moving objects.

[0002] In the industrial sector, repetitive tasks are increasingly being entrusted to automated systems.

[0003] During the performance of some of these tasks, objects are grabbed and then moved from one location to another, for example between a storage location and a machine tool on which the part undergoes operations.

[0004] When a part is to be grasped, the gripping device takes a specific position relative to it to ensure that the connection is made between the gripping device and the part and to ensure that there is no risk of the object falling during its handling.

[0005] Some objects have shapes that can be complex to manipulate.

[0006] There are automated systems equipped with a gripper or suction cup, however, they cannot handle objects of very different shapes and sizes. Furthermore, depending on the shape of the object, the secure attachment between the object and the gripping device is not guaranteed.

[0007] In addition, it is important to control the orientation of the parts when they are placed on the machine tool in order to ensure correct positioning relative to the tools, or when they are stored in order to avoid damaging them and to optimize the number of parts stored. Description of the invention

[0008] It is therefore one of the aims of the present application to provide a gripper device for automated systems that does not have the above disadvantages.

[0009] The stated objective is achieved by a gripping device comprising a platform and at least three fingers articulated on the platform with a longitudinal axis, and a single actuator for all the fingers. Each finger has two limbs, each formed by a parallelogram, and gripping means at its free end. The gripping means include, for example, a jaw capable of moving longitudinally and an actuator associated with the jaw and / or a suction cup.

[0010] The double parallelogram structure and the use of a single actuator allow for single control and simultaneous movement of the gripping means. Furthermore, the gripping means move in the same plane. This ensures secure handling of the parts and improves their orientation.

[0011] Furthermore, using a single actuator for all fingers simplifies finger control. Synchronizing the actuators of all fingers is no longer required, as this synchronization is imposed on all fingers by the actuator and the double parallelogram shape. In addition, having only one actuator reduces the weight of the device, which is particularly advantageous since the gripping device is generally suspended from an arm of a programmable logic controller (PLC).

[0012] Furthermore, the double parallelogram structure allows the arrangement of the gripping means to be adapted to the diameter of the object. The device according to the invention can thus grasp objects of different dimensions, in particular of different diameters.

[0013] Furthermore, when the jaws have a possibility of longitudinal movement, the device adapts to objects of different heights.

[0014] The combination of jaws and suction cups advantageously allows for a wider range of manipulable part shapes.

[0015] For example, the finger actuator is an electric piston.

[0016] The present invention then relates to a grasping device for an object comprising a platform with a longitudinal axis and at least three fingers articulated in rotation on the platform and grasping means carried by each of the free ends of the fingers, the at least three fingers being distributed angularly in a regular manner around the longitudinal axis, each finger comprising a double parallelogram linkage comprising a first parallelogram articulated on the platform around an axis orthogonal to the longitudinal axis, a second parallelogram being articulated on the first parallelogram and a set of gears between the first parallelogram and the second parallelogram, such that the displacement in one direction of rotation of the first parallelogram imposes a displacement in an opposite direction of rotation of the second parallelogram, and an actuator carried by the platform and configured to move all the fingers simultaneously.

[0017] In one embodiment, the gripping means comprise suction cups, each finger having at its free end a suction cup intended to be connected to a suction system.

[0018] In an advantageous example, the grasping means comprise bits, said bits being mounted on all or part of the fingers.

[0019] Preferably, the gripping device includes means for moving at least part of the gripping means relative to the free end of the fingers along the longitudinal axis.

[0020] For example, the means of movement comprise for each of said grasping means an electric motor and a rack and pinion system.

[0021] Preferably, the actuator is an electric piston aligned with the longitudinal axis and carried by the platform.

[0022] For example, the device includes a system for converting the linear displacement of the electric piston into a rotational movement of each of the fingers, said means being of the cam type.

[0023] According to an additional feature, the first parallelogram comprises two brackets, one of which is fixed on the platform, and two parallel arms each articulated on the two brackets and one of the arms comprises an inclined portion mechanically connected to the actuator via a connecting rod.

[0024] Most advantageously, the gripping device includes means for detecting the object to be grasped and for measuring the distance between the gripping device and the object, for example a laser sensor.

[0025] Preferably, the gripping device comprises six fingers, each equipped with a suction cup and three of the six fingers also equipped with a jaw.

[0026] The present invention also relates to an automaton comprising at least one gripping device according to the invention. Brief description of the drawings

[0027] This application will be better understood with the aid of the following description and the attached drawings, in which: [Fig. 1] is a schematic representation of an example of an automated machine equipped with an example of a gripping device according to the invention, [Fig.2] is a side view of an example of a gripping device according to the invention, [Fig.3] is a top view of the gripping device of [Fig.2], [Fig.4] is a cross-sectional view of [Fig.3] along plane AA, [Fig. 5] is a perspective view of the grasping device of [Fig. 1] in another configuration and is not relevant. [Fig.6] is a perspective view of the gripping device of [Fig.1] in another configuration, in which an object is grasped by all the suction cups, [Fig.7] is a schematic representation of an example of an object that can be manipulated using the jaws of the gripper device of [Fig.2]. DETAILED DESCRIPTION OF IMPLEMENTATION METHODS

[0028] In [Fig.1], a schematic representation can be seen of an example of an automaton A equipped with an example of a gripper device DI according to the invention holding an object O.

[0029] The automaton A comprises a base 2, a first arm 4 articulated on the base 2, a second arm 6 articulated on the first arm 4 and the gripper device DI fixed to the free end of the second arm 6.

[0030] The actuation of arms 4, 6 allows the grasping device Dl to be moved in the three directions of space.

[0031] It will be understood that the gripping device Dl can be attached to any other type of automaton.

[0032] Figures 2 to 6 show an example of an embodiment of the gripper Dl.

[0033] In this example, the device Dl has six fingers, but this number is not limiting, as we will see below.

[0034] The device Dl comprises a support 8 intended to be fixed to the arm 4 of the automaton, a platform 10 fixed to the support and articulated fingers on the platform 10.

[0035] The device has a longitudinal axis X.

[0036] The platform 10 is rigidly fixed to the support, for example by means of rods 12 providing between them windows for fingers.

[0037] The fingers are regularly spaced at angles around the X-axis. Each finger is rotationally articulated on the platform as described below. Each finger is articulated about an axis orthogonal to the X-axis.

[0038] Advantageously, an actuator Al ([Fig.4]) mounted on the platform 10 ensures the movement of all the fingers simultaneously.

[0039] In this example, the fingers are of two types. The fingers 13 have a short jaw M, a long jaw M' and a suction cup V, and the fingers 14 have a suction cup V. The fingers 13 and the fingers 14 are arranged alternately around the axis X.

[0040] A device comprising fingers equipped only with jaws or only with suction cups falls within the scope of the present invention.

[0041] In this example and advantageously, a set of suction cups V' is fixed to the platform 10. The suction cups V' are used in place of the suction cups V or in combination with the suction cups V. The suction cups V' can be mounted on a ball joint.

[0042] We will describe the fingers 13 in detail. The fingers 14 have a similar structure to that of the fingers 13, except with regard to the bits.

[0043] As can be seen in [Fig.2], each finger 13 has a linkage with two parallelograms PI, P2.

[0044] The parallelogram PI comprises two arms 24, 26 parallel to each other and two brackets 28, 30. The bracket 28 is fixed on the platform 10. Each arm 24, 26 is articulated by one end 24.1, 26.1 on the bracket 28 around an axis Yl, Y2 orthogonal to the axis X, and by another end 24.2, 26.2 on the bracket 30 around an axis Y3, Y4 parallel to the axes Yl, Y2.

[0045] The second parallelogram P2 comprises the bracket 30, two arms 32, 34 parallel to each other, and a bracket 36. Each arm 32, 34 is articulated at an end 32.1, 34.1 on the bracket 30 about an axis Y5, Y6 parallel to the axes Y1, Y2 and by a other end 32.2, 34.2 articulated on the console 36 around an axis Y7, Y8 parallel to the axes Y1, Y2.

[0046] The arm 24 has, at its end 24.1, a fixed pinion 38 moving with the arm 24 and the arm 32 has, at its end 32.1, a fixed pinion 40 moving with the arm 32. The pinions 38, 40 mesh with each other so that the direction of rotation of the arm 32 is opposite to the direction of rotation of the arm 24.

[0047] Due to the double parallelogram structure and the pinions 38, 40, when the arm 24 has a downward displacement in the representation of [Fig.4], the arm 32 and the arm 34 rise up, as well as the console 36.

[0048] When the parallelograms PI and P2 deform, the bracket 36 has a displacement along the X axis and a radial displacement in approach and away from the X axis.

[0049] The console 36 fulfills the function of supporting the gripping means.

[0050] In this example, the gripping means comprise a suction cup V, a jaw A short jaw M and a long jaw M'. The use of a long jaw and a short jaw allows for gripping objects of different dimensions, particularly of different heights. Gripping means comprising only a short jaw or only a long jaw do not fall outside the scope of the present invention.

[0051] The actuator Al is, in this example and advantageously, a linear actuator, for example an electric piston capable of generating a movement along the X axis.

[0052] Very advantageously the actuator Al is positioned along the X axis and is fixed between the platform and the support.

[0053] The moving part of the actuator Al is mechanically connected to the first parallelogram of each finger 13, 14, so that its linear displacement along the X axis causes a displacement of the arms 24, 26.

[0054] In [Fig.3], an example of a transmission system between the linear actuator and the fingers can be seen.

[0055] In this example and advantageously, the transmission system is a cam system.

[0056] The arm 26 comprises a first part 42 extending along an axis ZI articulated in rotation on the console 28 around the axis Y2. The arm 26 comprises a second part 46 forming an angle with the first part and extending in the direction of the axis X.

[0057] The transmission system also includes a connecting rod 48 linking the moving part of the electric piston and the free end of the second part 46 of the arm 26.

[0058] Thus, a linear upward displacement of the moving part of the actuator Al in the representation of [Fig. 4] causes a downward rotation of the arm 26 and a radial movement away from the console 36. Conversely, a downward displacement of the The moving part of the actuator Al causes the arm 26 to rotate upwards and the console 36 to move radially closer together.

[0059] In order to activate all the arms 13, 14 simultaneously, six connecting rods 48 are implemented and are articulated on the moving part of the actuator Al by means of a ring fixed in translation to the moving part of the actuator and on which the connecting rods are articulated.

[0060] Thus, by implementing a single actuator, all the fingers are deployed or retracted simultaneously.

[0061] In addition, due to the realization of the double parallelogram fingers, all the consoles 36 carrying the gripping means are permanently in the same plane, which is orthogonal to the X axis.

[0062] Alternatively, the linear actuator is a hydraulic actuator.

[0063] The use of a single actuator simplifies the control. This ensures mechanical synchronization of all the fingers and positioning of all the jaws and suction cups in the same plane. Furthermore, the suspended mass is reduced, and the overall size is significantly smaller.

[0064] In another embodiment, each finger has its own actuator. In this case, these may be rotary actuators directly driving one or the other of the arms 24, 26 in rotation.

[0065] The suction cup V is mounted at the end of a rod 50 fixed to the bracket. The suction cup is advantageously mounted on a ball joint to adapt to the different configurations of the objects to be gripped. Furthermore, the suction cup V is advantageously spring-mounted to absorb errors in the X direction.

[0066] Air suction means (not shown) are provided to generate a vacuum between the suction cup and the surface of the object to be moved in order to ensure that the suction cup adheres to the surface of the object. These means include a tube connecting the inside of the suction cup to a vacuum source.

[0067] A valve, advantageously a solenoid valve, allows the vacuuming and venting of the inside of the suction cup to be controlled in order to secure or, on the contrary, separate the suction cup and the object.

[0068] The suction cups V' are also connected to the air suction circuit and are controlled separately from the suction cups V'.

[0069] The gripping device may include a pneumatic circuit to which all the suction cups are connected, the pneumatic circuit being intended to be connected to a vacuum source. Advantageously, the vacuum control for all the suction cups is centralized.

[0070] The gripping means also include a short jaw M and a long jaw M' for grasping objects other than those graspable by suction cups, for example, objects with an annular structure. Advantageously, the long jaw M' is movable longitudinally at the free end of the finger by means of a DC electric motor A2. The jaw M' then moves along the X-axis, making it possible to grasp objects of different heights. Furthermore, this allows the jaw to be moved away from the suction cup mounted on the same bracket, facilitating its placement on an object.

[0071] In the example shown, the movement means comprise two racks 52 at the ends of which the jaw is mounted, and an electric motor carried by the bracket 36, which is coupled to the racks by means of gears. Other means for moving the jaws can be implemented, for example a worm gear system. A single rack could be used.

[0072] Advantageously, each long jaw M' is movable separately, which allows, for example, the movement of an object, such as a ring, by moving one of the long jaws M' along the X-axis to cooperate with the inner edge of the ring. By moving the device, the ring is pulled by the cooperation of the jaw M' and the inner edge of the ring.

[0073] Alternatively, the jaws are fixed longitudinally.

[0074] Preferably, high and low position sensors are implemented for each rack. Alternatively, an encoder on the motor and a position sensor are provided.

[0075] The jaw, viewed from the side, is a U-shaped form configured to accommodate a portion of the contour of the object to be moved. The distance separating the two arms of the U defines the maximum thickness of the part of the object that is gripped.

[0076] Advantageously, the jaws are interchangeable, allowing the spacing between the arms of the U to be adapted to the objects to be gripped. Alternatively, the distance between the arms of the U is adjustable.

[0077] Alternatively, the suction cups are capable of moving longitudinally.

[0078] In the example shown, the rods carrying the suction cups are inclined with respect to the X-axis and the suction cups are oriented towards the X-axis, making the gripping device suitable for grasping convex objects. The suction cups have a certain degree of flexibility, and the ball joint mounting allows it to adapt to different convexities.

[0079] Alternatively, the rods carrying the suction cups are parallel to the X axis, allowing the manipulation of flat objects, or the rods carrying the suction cups are inclined with respect to the X axis and the suction cups are oriented away from the X axis allowing the manipulation of concave objects.

[0080] Preferably, the device includes means for detecting the presence of the part to be grasped and for measuring the distance between the object and the device in order to manage the approach of the device to the object during the grasping phase and to control the activation of the fingers and the grasping means.

[0081] For example, the device includes at least one laser sensor C fixed on the platform allowing the distance between the gripping means to be determined.

[0082] The detection that an object has been gripped or sufficiently gripped can be obtained by measuring the level of vacuum in the suction cups or, in the case where the jaws are used, by measuring a clamping torque via the electric actuator.

[0083] As an alternative or in addition, the device includes camera-type optical sensors and / or ultrasonic sensors.

[0084] The control of actuator A1 and each of the motors A2, and the processing of signals transmitted by the sensor(s), are carried out by a control unit (not shown). This unit can be mounted on the gripper device and receive instructions from the PLC, or it can be located on the PLC itself.

[0085] Examples of the operation of the gripping device will now be described.

[0086] In a first example, the object to be grasped is a convex lid O as shown in [Fig.2].

[0087] The gripper device is fixed to the free end of a programmable logic controller (PLC) as shown in [Fig. 1] and is electrically connected to a power source, for example, that of the PLC, to power the actuator A1 and the electric motors. Furthermore, the pneumatic circuit of the suction cups is connected to a vacuum system.

[0088] The automated system moves the gripper device so that it is positioned above and near the object to be grasped. The movement of the gripper device is guided by signals emitted by the sensors and processed by the control unit.

[0089] When the X-axis of the device is approximately aligned with the axis of the lid, the actuator is activated, causing all the fingers 13, 14 to extend and simultaneously lower towards the object until the suction cups make contact with the lid. A vacuum is then generated in each of the suction cups. The lid is then secured to the suction cups and can be moved.

[0090] When the lid is placed in its new location, the vacuum is broken in the suction cups and the lid is released.

[0091] In a second example, the object to be grasped has an annular shape O” as shown in [Fig.7]. The jaws are used.

[0092] The gripper device is fixed to the free end of an automaton as shown in [Fig.1].

[0093] The automaton moves the gripper device so that it is positioned above and near the object to be grasped. When the X-axis is approximately aligned with the axis of the object, the actuator is activated, causing a radial deployment and simultaneously a lowering of all the fingers towards the object until the jaws radially surround the hollow object.

[0094] The actuator is then activated in the opposite direction to cause a radial approach of the jaws in the direction of the X axis which, simultaneously, move upwards, until the jaws receive a portion of the circumference of the hollow object and until the bottom of the jaws comes into contact with the circumference and immobilizes the object.

[0095] The object is then fixed to the gripping device and can be moved.

[0096] When the object is positioned in its new location, the actuator Al is commanded to move the jaws radially outwards and upwards and release the object.

[0097] Thanks to the movement of all the jaws in the same plane, it is possible to easily grasp relatively thin objects.

[0098] In [Fig.5], we can see the DI device in which the long jaws M' are fully deployed along the X axis.

[0099] In [Fig.6], the DI device can be seen in another configuration for moving an object O' using the suction cups V and V'. In this configuration, the fingers 13 are folded.

[0100] The device according to the invention allows for the manipulation of objects of various dimensions and shapes.

[0101] In the embodiment using both suction cups and jaws, the gripping device can manipulate solid and hollow objects. Furthermore, it can manipulate, by means of the suction cups, objects that do not have a geometry of revolution.

[0102] In addition, it can grasp objects of varying diameters by means of the jaws.

[0103] In the example shown, three fingers are fitted with bits and all six fingers are each equipped with a suction cup. The device according to the invention comprises at least three fingers, preferably distributed angularly at 120° to each other, to ensure a regularly distributed grip on the contour of the objects, and which allows to ensure a balanced distribution of the load on the gripping device.

[0104] During its movement, whether or not it is carrying an object, the gripping device can assume any position: horizontal, vertical, or inclined. It is also possible to turn it over so that the free ends of the fingers point upwards.

Claims

Demands

1. An object-gripping device comprising a platform (10) with longitudinal axis (X) and at least three fingers (13, 14) rotationally articulated on the platform (10), and gripping means carried by each of the free ends of the fingers (13, 14), the at least three fingers (13, 14) being regularly angularly distributed around the longitudinal axis (X), each finger (13, 14) comprising a double parallelogram linkage including a first parallelogram (PI) articulated on the platform (10) about an axis orthogonal to the longitudinal axis (X), a second parallelogram (P2) being articulated on the first parallelogram (PI), and a set of gears (38, 40) between the first parallelogram (PI) and the second parallelogram (P2), such that a displacement in one direction of rotation of the first parallelogram (PI) imposes a displacement in a direction of rotation opposite to the second parallelogram (P2),and an actuator (Al) carried by the platform and configured to move all the fingers simultaneously (13, 14).

2. Gripping device according to claim 1, in which the gripping means comprise suction cups (V), each finger (13, 14) having at its free end a suction cup (V), intended to be connected to a suction system.

3. Gripping device according to claim 1 or 2, wherein the gripping means comprise jaws (M), said jaws being mounted on all or part of the fingers (13).

4. Gripping device according to any one of claims 1 to 3, comprising means for moving at least a part of the gripping means relative to the free end of the fingers along the longitudinal axis (X).

5. Gripping device according to claim 4, wherein the means of movement comprise for each of said gripping means an electric motor and a rack and pinion system (52).

6. Gripping device according to any one of the preceding claims, wherein the actuator (Al) is an electric piston aligned with the longitudinal axis (X) and carried by the platform (10).

7. A gripping device according to any one of the preceding claims, comprising a displacement conversion system linear of the electric piston in a rotational movement of each of the fingers (13, 14), the conversion system being of the cam type.

8. Gripping device according to claim 7, wherein the first parallelogram (PI) comprises two brackets (28, 30), one of which bracket (28) is fixed on the platform (10), and two parallel arms (24, 26) each articulated on the two brackets (28, 30) and wherein one of the arms (26) comprises an inclined portion (46) mechanically connected to the actuator (A1) via a connecting rod (48).

9. Gripping device according to any one of claims 1 to 8, comprising means for detecting the object to be grasped and for measuring the distance between the gripping device and the object, for example a laser sensor (C).

10. Gripping device according to any one of the preceding claims, comprising six fingers (13, 14), each equipped with a suction cup (V) and three of the six fingers also equipped with a jaw (M).

11. Automaton comprising at least one gripping device according to any one of the preceding claims.

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