A DEVICE FOR PICKING UP AND MANIPULATING SHEET-LIKE, FLEXIBLE OBJECTS, PARTICULARLY EXPENSIVE FABRICS

Abstract: The device is provided with at least one gripper (12) comprising a first gripping member (13) which can adhere by contact to a face of the object to be picked up and a second gripping member (14) which can press the object gripped against the first gripping member (13) and keep it in a firmly gripped condition by acting on the opposite face of the object to be picked up, the second gripping member (14) being formed as a pincer with a first jaw (15) carrying the first gripping member and a second jaw (16) movable away from and towards the first jaw (15).

Description: A device for picking up and manipulating sheet-like, flexible objects, particularly expensive fabrics Technical field The subject of the present invention is a device for picking up and manipulating sheet-like, flexible objects, particularly expensive fabrics, according to the preamble to Claim 1. The invention also relates to a method of picking up and manipulating sheet-like flexible objects utilizing the above- mentioned device. Technical background A device including the above-mentioned characteristics is known from published Japanese patent applications Nos. 61101351 and 61101343 in the name of Tokyo luki Ind. Co. Ltd. These documents describe the use of gripping devices each comprising a first pneumatic suction gripping member which can adhere by contact to a face of an edge portion of fabric to be manipulated and a second gripping member which can press the fabric against the first gripping member and keep it pressed in a firmly gripped condition by acting on the opposite face of the edge portion . With reference to the gripping devices of these documents, it should be noted that they operate in accordance with a relatively lengthy and labourious picking-up process which requires the fabric to be lifted to a certain height by means of the pneumatic suction device and to be restrained whilst awaiting the completion of three operations (lowering the second gripping member, rotating it in order to bring it beneath the fabric in the region of the suction device, and then raising it against the latter) in order for the fabric to be gripped. Moreover, once the fabric has been lifted, because of its own weight, the fabric in the region of the suction device undergoes a local deformation which tends to favour its detachment. Furthermore, it should be noted that the gripping device requires at least two independent actuators, of which one is subjected to two distinct operations, and the gripping device enables gripping to take place exclusively in peripheral regions of the piece of fabric and is not suitable for gripping in central regions of the piece. For this reason, it also takes up working space which may invade the space outside the piece to be manipulated. It should also be noted that the solution proposed is designed predominantly for moving whole pieces of fabric and not for picking up individual cut pieces and removing them from the off-cuts. Finally, the devices do not have any means which render them suitable for handling particularly delicate and expensive materials such as cashmere, silk and any materials which are liable to retain impression marks. A device for picking up and manipulating plastics sheets is described in published European patent application No. 0111739. Since the manipulation of materials impermeable to air is involved, this device makes use of separate first and second gripping members of which the first gripping member is a pneumatic suction device and the second gripping member is a pincer device. The operation of the separate gripping members described cannot be proposed for the manipulation of fabrics, particularly for picking up and manipulating pieces which are highly permeable to air, especially if they are disposed between off-cuts. Description of the invention The problem upon which the present invention is based is that of providing a novel picking-up and manipulation device which is also capable of handling, with a firm but light grip, materials which may be quite difficult to pick up and manipulate, particularly expensive fabrics and cut portions thereof, at the same time preventing the problems complained of with reference to the acknowledged prior art. This problem is solved by the invention by a picking-up and manipulation device formed in accordance with Claim 1. Further advantages are achieved by the technical solutions of the subordinate claims. Brief description of the drawings The characteristics and advantages of the invention will become clearer from the following detailed description of a preferred embodiment thereof, described, by way of non- limiting example, with reference to the appended drawings, in which: Figure 1 is a schematic, perspective view of apparatus for the manipulation of flexible objects including a picking- up device formed in accordance with the present invention, Figure 2 is a perspective view showing a detail of the apparatus of Figure 1, on an enlarged scale, Figures 3 and 4 are a perspective view and a front elevational view, respectively, of the picking-up device with which the apparatus of Figure 1 is equipped, Figures 5 and 6 are a side elevational view and a perspective view, respectively, of a gripper with which the picking-up device of the preceding drawings is equipped, Figure 7 is a perspective view of a detail of the device of Figures 5 and 6, Figure 8 is a side elevational view of another detail of the device of Figures 5 and 6, Figure 9 is a side elevational view of a further detail constituting alternative equipment of the gripper of Figures 5 and 6, and Figures 10 to 12 are schematic views of the device of the invention in different operative stages. Preferred method of implementing the invention In Figure 1, an apparatus for manipulating flexible objects is generally indicated 1 and utilizes a picking-up device 2 disposed on a vertical slide 3 of a Cartesian robot 4 which, with regard to the aspects not expressly described, is of conventional type. The picking-up device 2 comprises a cross member 3a (Figure 3) mounted on the slide 3 by means of a mechanical wrist 6 which can bring about angular orientations of the cross member about three (or more) axes X, Y, Z. The mechanical wrist is also of a type known to experts in the art . A motor 8 controls the movement of two further slides 10a, 10b, by means of a geared transmission 11. The further slides 10a, 10b are driven by means of screws with recirculating balls or other equivalent mechanisms, also of conventional type, and serve to translate two grippers, both- indicated 12 and each mounted on a respective slide 10a, 10b, away from and towards a central position beside the geared transmission 11. Since the grippers are identical, only one of them will be described in detail. Each gripper 12 comprises a first gripping member 13 and a second gripping member 14 combined in the following manner. The second gripping member is formed as a pincer with a first, fixed jaw 15 and a second jaw 16 which is movable in accordance with a law of motion defined by an articulated parallelogram mechanism in which the first jaw is fixed to a fixed bar 18 of the parallelogram whereas the second jaw is fixed to a connecting rod 19 thereof. The fixed bar 18 and the connecting rod 19 are connected to one another by means of first and second rocker arms 20, 21, the rocker arm 20 being pivoted relative to the fixed bar 18 by a pneumatic ack 22. The seconα aw 16 is covered by a resilient pad 25 ana, in the embodiment illustrated, has a substantially square shape in plan. The first aw 15 comprises a forc-shapeα support 27 between prongs 27a, 27b and a base 28 of which an approximately square aperture 29 is formed ana houses the first gripping member 13, preferably m a releasable, replaceable manner. In a preferred embodiment of the invention, the first gripping memoer 13 is, interchangeably, a pneumatic suction device 30 or a mechanical gripping device 33, for example, witn needles, with an adhesive surface, or covered with hooks sucn as those typically present m pull fastenings of the type known by the registered traαe mark VELCRO (TM) . The pneumatic suction device 30 has appendages 30a, by means of which it is housed and guided between the prongs 27a, 27b, and a perforated suction surface 30b communicating with a manifold 30c connected to an air-suction hose. The mechanical gripping device 33 is preferably movable away from and towarαs the aperture 29, by means of a ack actuator 32, between an operative position m which tne active surface of the device 33 is at the level of the lower surfaces of the prongs 27a, 27b and a detacnment position of the device 33 m which it is moved away from the prongs 27a, 27b which act as reaction members to favour the detachment of the fabric gripped from the above-mentioned active surface when the movable jaw 16 is closed onto the fixed jaw 15. The vertical mobility of the mechanical gripping device, is superfluous, however, in the case of the pneumatic suction device since the fabric can readily be detached by the reversal of the air-flow through the suction device 30. Finally, a photocell or other similar presence detector, indicated 34, is mounted on the first jaw 15 to detect the gripping between the jaws 15, 16 of the piece to be manipulated. With reference to Figures 10 to 12, a piece of a garment cut to the desired shape on a cutting table is indicated 50. The piece 50 is to be removed from a fabric off-cut, indicated 51, if possible without moving the off-cut so that other cut pieces lying on the cutting table can be identified and found by the picking-up device of the invention solely with reference to their positions relative to an origin point stored by the cutting apparatus. In order to grip and subsequently manipulate the piece 50, after the Cartesian robot 4 has been positioned, the picking-up device 2 is driven in a manner such that each gripper 12 is disposed above the piece to be gripped with the perforated surface of the pneumatic suction device 30 substantially parallel to the plane of the cutting table. The cross member 3a is then lowered until the pneumatic suction devices 30 contact the piece to be picked up. Upon activation of the pneumatic suction device, the piece adheres to the perforated active surface of the suction device 30 with the desired lightness of contact and is lifted, together with the cross member 3a. The lifting of the cross member 3a is coordinated with a rotary movement of the mechanical wrist 6 in the direction shown by way of example in Figure 11, that is, about an axis substantially parallel to the plane of closure of the second gripping member (the mutually facing surfaces of the jaws 15, 16) so as to orient the closure plane in a manner consistent with the deformation of the piece gripped due to its own weight and to its mechanical characteristics during its lifting. This minimizes the tendency of the gripped fabric to become detached and improves the firmness of the grip of the pneumatic suction device in comparison with a simple vertical lifting movement of the fabric, ensuring that the fabric is held correctly until the operation of the second gripping members is complete. These second gripping members are operated at the moment at which the lifting permits the closure movement of the jaws 15, 16. The geometry selected for the articulated parallelogram mechanism permits a notably small travel of the movable jaw 16 in the direction perpendicular to the plane of the first fixed jaw 15, enabling the jaws to be closed after a very limited lifting of the piece. The jack 22 moves the rocker arm 20 so that the second jaw 16 is closed onto the first jaw 15. It should be noted that the second jaw has a relatively extensive active surface so as not to damage the fabric being handled. The surface of the first jaw is also extensive, particularly f it is supplemented by the surface of the first gripper, so that even the most delicate fabrics can be manipulated witn complete safety and with relatively low closure pressures cetween the aws. Once the pincer is closed and possibly detacned from the piece, the mechanical gripping device 33 continues the desired movement by means of the ack 32, possibly with the subjection of tne mechanical wrist 6 to a rotary-translational movement resulting n a rotary-translational movement of the two grippers 12, favouring the spontaneous detachment of the piece 50 from the offcut 51 without causing unαesired displacements thereof. With this technique for collecting the piece from the cutting table, the cut piece is advantageously detached from the production off-cut vertically, cancelling out the effect of entrainment of the piece and of the off-cut, which may assume a certain importance according to the material and tne geometry of the cut piece. Amongst the aι;_ advantages of the invention, the following should be noted: - the first gripping member s required, before tne intervention of the second gripping member, to lift only the edge of the piece gripped (that is, a minimal mass), every subsequent lifting effect being supported entirely by the second gripping member, - the pickmg-up device is adaptable to various materials and different geometries by virtue of the mtercnangeability of the first gripping members and of the wide adaptability of the second gripping members, - the movements of the device, m comparison with known devices with articulated arms, are compact and simple, - control and coordination of the pickmg-up device is facilitated because the movements of several grippers mounted on the same cross-meiujoer can be coordinated, - t is possible to pick up botn large pieces with tne use of several grippers spaced apart on the cross-memoer, and small pieces with the use even of a single device, or by moving the devices towards one another along the cross-member, - it is possible simultaneously to pick up two or more pieces arranged symmetrically with respect to a line, - the speed of closure of the aws is increased and a minimum number of actuators is required for the operation of the gripper, - a reliable grip is effected by virtue of the purely mechanical second gripping stage, - a reliable grip is effected 111 the first gripping stage by virtue of the rotary-translational movement imparted to the pickmg-up device, - it is possible to grip pieces even m their central regions, folding them into two portions one en top of the other.

Claims: CLAIMS 1. A device for picking up and manipulating sheet-like, flexible objects, particularly expensive fabrics, including at least one gripper (12) comprising a first gripping member (13) which can adhere by contact to a face of the object to be picked up and a second gripping member (14) which can press the object gripped against the first gripping member (13) and keep it pressed in a firmly gripped condition by acting on the opposite face of the object to be picked up, characterized in that the second gripping member (14) is formed as a pincer with a first jaw (15) carrying the first gripping member and a second jaw (16) movable away from and towards the first jaw (15) . 2. A device according to Claim 1 in which the second jaw (16) is associated with an actuator which can implement a predefined relative motion between the jaws (15, 16) comprising a translational movement and simultaneous progressive closure of the second jaw (16) onto the first (15), the jaws being kept substantially parallel to one another. 3. A device according to Claim 1 or Claim 2, in which the actuator comprises an articulated parallelogram mechanism, the first jaw (15) being stationary relative to a fixed bar (18) of the parallelogram and the second jaw (16) being mounted on a connecting rod (19) of the parallelogram. 4. A device according to one or more of the preceding claims, in which the at least one gripper (12) is guided on a cross- member (3a) so as to be translatable and adjustable along the cross-member, and translational drive means (8, 11) are provided for moving the at least one gripper (12) along the cross-member (3a) . 5. A device according to Claim 4, in which two or more grippers (12) are provided on the same cross-member (3a) . 6. A device according to one or more of the preceding claims, in which the at least one gripper (12) is mounted on a mechanical wrist (6) articulated about a first axis substantially parallel to the plane of closure of the jaws (15, 16) , the wrist being driven for rotation about the said axis so as to orient the closure plane in a manner consistent with the deformation of the object gripped due to the object's own weight, during the lifting thereof. 7. A device according to one or more of the preceding claims, in which the first jaw (15) comprises an aperture (29) through which the first gripping member (13) acts. 8. A device according to Claim 7, in which the first jaw (15) comprises a fork-like element (27) , between prongs (27a, 27b) of which the aperture (29) is defined. 9. A device according to Claim 7 or Claim 8, in which the first gripping member (13) is selected from a pneumatic suction device (30) and a mechanical gripping device (33), for example, with needles, with an adhesive surface, or the like. 10. A device according to Claim 9, in which the first gripping member (13) is associated releasably with the first jaw (15) and is, interchangeably, the mechanical gripping device (33) and the pneumatic suction member (30) . 11. A device according to one or more of Claims 8 to 10, in which respective active surfaces of the first jaw, against which the second jaw is urged upon closure, are defined on at least one prong (27a, 27b) and a base of the fork-like element. 12. A method of picking up and manipulating sheet-like, flexible objects, particularly expensive fabrics, including the steps of causing a first gripping member (13) of a gripper (12) to adhere by contact to a face of the object to be gripped, lifting the object by means of the first gripping member and subsequently pressing the object gripped against the first gripping member (13) and keeping the object pressed in a firmly gripped condition by acting on the opposite face of the object to be picked up, characterized in that the lifting by means of the first gripping member (13) is limited purely to an edge of the object to be picked up, the remaining lifting and/or manipulation of the object being effected by the operation of a second gripping member (14) . 13. A method according to Claim 12, in which the at least one gripper (12) is mounted on a mechanical wrist (6) articulated about an axis substantially parallel to the plane of closure of the jaws (15, 16) of the second gripping member (14), characterized in that, during the lifting at least of the edge of the object to be picked up, the wrist (6) is rotated about the axis so as to orient the closure plane in a manner consistent with the deformation of the object gripped due to its own weight and/or to the mechanical characteristics of the object, during the lifting thereof.

Inventors: MALASPINA MARCO, MALASPINA, MARCO
Applicants: CLAUDIO E CARLALBERTO CORNELIA, MALASPINA MARCO, F.LLI CLAUDIO E CARLALBERTO CORNELIANI S.P.A., MALASPINA, MARCO
Application year: 1998
Main classification: B65H3
IPC codes: B65H3, B65H5