DE102021205830A1 - Gripper for the automated picking up of disordered workpieces - Google Patents

Abstract

The invention relates to a gripper for the automated picking up of disordered workpieces, having a base body (8), guide elements (4) being mounted on the base body (8) so that they can be moved in a translatory manner and the guide elements (4) receiving contact elements (6), the contact elements (6) are movably mounted on the guide elements (4) by means of joints (5).

Description

The invention relates to a gripper for the automated picking up of unordered workpieces, having a base body, with guide elements being mounted on the base body so that they can be moved in a translatory manner, with the guide elements receiving contact elements.

Furthermore, the invention relates to a handling device with such a gripper and a method for the automated gripping of workpieces.

There are known grippers for the automated picking up of workpieces, which automatically grip workpieces by means of vacuum suction cups or magnets. Greater demands are placed on gripper devices that can grip workpieces that are stored in a container in a disorderly manner. In particular, if the workpieces are not only larger and heavier, but also have a large number of steps, projections or depressions, such as body parts, and therefore have little or no flat areas, automated gripping must be developed specifically for the workpiece and is costly, so that such workpieces are regularly removed by hand containers are removed.

From the DE 10 2018 111 647 A1 a gripping device for a robot is known, which is provided for picking up body parts and can grip different geometries and surface textures. For this purpose, gripping elements are mounted in guide elements of a receiving device so that they can be moved in a translatory manner independently of one another. The contact areas fixed immovably on the gripping elements can thus be moved out of the receiving device to different extents and approach a workpiece geometry. The workpiece is held on the contact surfaces by means of magnetism.

It continues through the DE 10 2014 219 381 A1 a gripper device is known for the automated gripping of workpieces with at least two gripping field sections, which can be moved in a translatory manner relative to one another and perpendicularly to the displacement direction of gripping segments mounted in the gripping field sections. To grip the workpiece, the gripping segments, which are preferably pin-shaped, are displaced so that they thereby surround a workpiece. The gripping segments then come into contact with the workpiece by moving the gripping field sections relative to one another. A pivoting movement of the gripping panel sections relative to one another is also disclosed, which enables workpieces to be gripped in a form-fitting manner.

the U.S. 10,611,037 B1 discloses a gripping device for the automated gripping of workpieces that may have bumps and projections. The gripping device has a large number of vacuum suction cups, which are mounted individually so that they can be moved in a translatory manner relative to the gripping device, so that they can adapt to the contour of the workpiece. Gripping of smaller protrusions is achieved through the flexibility of the vacuum pad material, which conforms to the surface of the workpiece.

Against this background, the invention is based on the object of designing a gripper and a handling device and a method of the type mentioned at the outset in such a way that automated, rapid and reliable gripping of unordered workpieces can be implemented cost-effectively.

This object is achieved with a gripper according to the features of patent claim 1 and the features of the independent claims. The dependent claims relate to particularly useful developments of the invention.

According to the invention, a gripper for the automated picking up of unordered workpieces is provided, which has a base body, guide elements being mounted on the base body so that they can move in a translatory manner, the guide elements receiving contact elements, the contact elements being movably mounted on the guide elements by means of joints.

The main body of the gripper, which is preferably intended to be accommodated in a handling device, supports at least one guide element so that it can be moved in a translatory manner. This advantageously means that the gripper, in particular the base body of the gripper, can move to different positions for gripping the workpiece. Collisions of the gripper with interfering contours can be avoided. The gripper can thus move to a large number of positions for gripping a workpiece; gripping is possibly only made possible by this.

By mounting the contact elements on the guide elements by means of joints, it is advantageously achieved that the contact surfaces of the contact elements can be aligned with the surface of the workpiece. Angular errors between the contact surface and the workpiece can be compensated for, as a result of which the contact surfaces can be placed flat against workpieces, even if the gripper and thus the guide element are not aligned with the workpiece surface. This simplifies path planning for the gripper and also the requirements for it Sensory are thereby reduced. Furthermore, the gripping of poorly accessible workpieces is only made possible by the freer positioning of the gripper, with collisions of the gripper with interfering contours being avoided. Disorganized workpieces with a large number of contours may only become accessible automatically.

Magnetic grippers for ferromagnetic materials and vacuum suction cups have proven to be preferred embodiments of contact elements. Magnetic grippers can advantageously bridge smaller gaps and also grip workpieces in areas with recesses, whereas vacuum suction cups are particularly advantageous for non-ferromagnetic materials, since the contours of workpieces can be compensated for in certain forms by the vacuum suction cup itself.

A particularly practice-relevant embodiment has guide elements that move into a basic position, preferably an extended position, by means of reset devices, preferably pneumatic cylinders and also or alternatively springs. By moving the guide elements into a basic position, the guide elements are in a defined position, insofar as they are not in contact with a workpiece, so that the position of the guide elements does not have to be determined. A basic position in the extended position ensures that the contact elements make early contact with the workpiece when approaching a workpiece and, if possible, contact all contact elements with the workpiece. Pneumatic cylinders and springs have proven to be cost-effective and durable reset devices.

A preferred embodiment has a gripper with exactly one guide element, the guide element having exactly one contact element. Not only is a gripper that can be produced particularly cost-effectively made possible, but also a particularly compact gripper that has particularly good accessibility to unordered workpieces. An alternative embodiment has a multiplicity of guide elements, each with a contact element, with the guide elements preferably being arranged in a field relative to one another. The load capacity of the gripper is further increased by a large number of guide elements and contact elements. Advantageously, the guide elements are arranged in a field relative to one another, ie they are not located on a straight line, as a result of which a particularly compact design of the gripper is made possible even with a large number of contact elements.

A particularly practice-relevant embodiment has guide elements and contact elements, which are each mounted and moved independently of one another. The individual translatory mobility and the movable mounting of the contact elements on the guide elements make it possible for each contact element to come into contact with the material surface and for each contact element to align itself with the material surface that it contacts; a particularly effective gripping of the workpiece is made possible.

A preferred embodiment has a gripper that has a receptacle or coupling, in particular a quick-change coupling, for connection to a handling device. This enables the gripper on the handling system to be changed quickly and easily, so that the gripper can be effectively changed for different workpieces.

A particularly practice-relevant embodiment has a gripper that is intended to grip sheet metal, preferably formed or cambered sheet steel, more preferably body panels of motor vehicles. Disorganized metal sheets, in particular formed or cambered steel sheets, in particular car body panels with a high density of deformations and cambers, are particularly difficult to grip, and such a gripper can have a considerable cost advantage by avoiding manual work.

According to the invention, a handling device with a gripper according to the invention is also provided.

A method according to the invention for gripping a disordered workpiece, preferably with a gripper according to the invention, is provided, with the workpieces being scanned in a first step in order to determine workpiece coordinates using the scan data. A path plan is then determined based on the workpiece coordinates and interference contours, which is output to a controller. A handling device and a gripper are controlled with the controller, the gripper being moved by a handling system with individual adjustment of the individual guide elements by a resistance of the workpiece and the individual contact elements to a workpiece geometry.

An effective gripping of disordered, in particular strongly shaped or cambered workpieces is made possible by abutting and aligning all contact elements.

• 1 einen bekannten magnetischen Greifer;
• 2 einen Greifer mit Führungselementen in eingefahrener Stellung;
• 3 ein Führungselement mit Kontaktelement;
• 4 einen Greifer mit Führungselementen in teilweise ausgefahrener Stellung;
• 5 einen Greifer mit Führungselementen in unterschiedlichen Stellungen;
• 6 einen Greifer mit drei Führungselementen;
• 7 einen Greifer mit zwei Führungselementen;
• 8 einen Greifer mit einem Führungselement.

The invention permits numerous embodiments. To further clarify their basic principle, some of them are shown in the drawings provided and are described below. These show in

• 1 a known magnetic gripper;
• 2 a gripper with guide elements in a retracted position;
• 3 a guide element with contact element;
• 4 a gripper with guide elements in a partially extended position;
• 5 a gripper with guide elements in different positions;
• 6 a gripper with three guide elements;
• 7 a gripper with two guide elements;
• 8th a gripper with a guide element.

1 shows a magnetic gripper known from the prior art with a pole shoe 1 which is in contact with a workpiece via its contact body 2 with the contact planes 3 . The contact planes 3 are flat and only form line contacts with the workpiece, since the workpiece does not have any flat contact areas due to deformations and recesses. The magnetic field can therefore only exert a small force on the workpiece.

2 discloses a gripper with guide elements 4 in the retracted position, each of which supports a contact element 6 movably by means of a joint 5, which is designed as a ball joint. The contact elements 6 are in an initial position; they are aligned coaxially with the guide elements 4 by means of springs (not shown). The contact surfaces 7 of the contact elements 6 are oriented away from the guide elements 4 and are magnetic grippers in this embodiment.

The guide elements 4 are mounted in a base body 8 in a translatory manner along their main extension direction and can be moved parallel to one another by means of slide bearings 9 . The guide elements 4 are moved into an extended basic position by means of resetting devices (not shown), which can be implemented as pneumatic cylinders or springs, provided that no force moves them into the retracted position shown.

In this embodiment, the base body 8 consists of sheet metal, which can form the base body 8 by means of forming or as a welded construction. For quick and easy assembly or disassembly of the gripper from a handling system, the base body 8 has a receptacle 10 on the side opposite the contact elements 6 , which is designed as a coupling 11 .

In 3 a guide element 4 with a ball-bearing contact element 6 is shown in detail. The guide element 4 is designed as a shaft and has a diameter of 10 mm and a length of 100 mm and has a ball head on which the ball socket, which is connected to the contact element 6, is mounted. The contact element 6, a magnetic gripper, is cylindrical with a height of 30 mm and has a flat contact surface 7 with a diameter of 35 mm.

the 4 and 5 represent a gripper with partially extended guide elements 4, which is the embodiment of FIG 1 is equivalent to. The contact elements 6 are not in the starting position, but are shown in a position in which they grip a workpiece, for example. For this purpose, the contact surfaces 7 point in different directions. In 5 are two guide elements 4 shown further back and the associated contact elements 6 in the basic position or in the starting position and are not involved in the gripping process.

In the 6 , 7 and 8th are shown grippers, which basically the embodiment of 1 correspond, but have a smaller number of guide elements 4. In 6 the gripper has three guide elements 4, which are arranged on a straight line, so that a particularly compact gripper is made possible in one spatial direction. The embodiment of 7 has two guide elements 4 which are in a partially extended position in which they can grip a workpiece, for example. 8th discloses a gripper with only one guide element 4 and one contact element 6 in the basic position or in the starting position. This embodiment is particularly compact and allows gripping even in cramped spatial conditions.

reference list

1

pole shoe

2

contact body

3

contact level

4

guide element

5

joint

6

contact element

7

contact surface

8th

body

9

bearings

10

recording

11

coupling

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 102018111647 A1 [0004]
• DE 102014219381 A1 [0005]
• US 10611037 B1 [0006]

Claims (10)

Gripper for the automated picking up of disordered workpieces, having a base body (8), guide elements (4) being mounted on the base body (8) so that they can be moved in a translatory manner, contact elements (6) being mounted on the guide elements (4), characterized in that the contact elements ( 6) are movably mounted on the guide elements (4) by means of joints (5). grab after claim 1 , characterized in that the contact elements (6) are magnetic grippers or vacuum suction cups. Grab after the claims 1 or 2 , characterized in that the guide elements (4) are moved into a basic position, preferably an extended position, by means of restoring devices, preferably pneumatic cylinders and/or springs. Gripper according to at least one of the preceding claims, characterized in that the joints (5) are ball joints which are preferably returned to an initial position, preferably coaxial to the guide element (4), by means of spring elements. Gripper according to at least one of the preceding claims, characterized in that the gripper has at least exactly one guide element (4) with at least exactly one contact element (6), with a large number of guide elements (4) with contact elements (6) having the guide elements (4) are preferably arranged in a field to each other. Gripper according to at least one of the preceding claims, characterized in that the guide elements (4) and/or the contact elements (6) are each mounted and movable independently of one another. Gripper according to at least one of the preceding claims, characterized in that the gripper has a receptacle (10) or coupling (11), in particular a quick-change coupling, for connection to a handling device. Gripper according to at least one of the preceding claims, characterized in that the gripper is suitable for gripping sheet metal, preferably shaped and/or convex steel sheet metal, more preferably body panels of motor vehicles. Handling device according to at least one of the preceding claims, characterized in that the handling device has a gripper according to one of the preceding claims. Method for gripping a disordered workpiece, preferably according to at least one of the preceding claims, characterized in that disordered workpieces are scanned and workpiece coordinates are determined, a path plan being determined using the workpiece coordinates and interfering contours, the path plan being output to a controller and a handling device with the controller and a gripper are controlled, the gripper being moved to a workpiece geometry with individual adjustment of the individual guide elements (4) and the individual contact elements (6).

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