EP4106961A1

EP4106961A1 - Robot arm with gripper

Info

Publication number: EP4106961A1
Application number: EP21711023.8A
Authority: EP
Inventors: Helmut De Roovere; Kwinten WAUTERS
Original assignee: Robojob NV
Current assignee: Robojob NV
Priority date: 2020-02-20
Filing date: 2021-02-12
Publication date: 2022-12-28
Also published as: BE1028083A1; WO2021165800A1; BE1028083B1

Abstract

Functional gripper head (1) for a robot arm (2), which functional gripper head (1) comprises a guide plate (3) with gripper fingers (4), which gripper fingers (4) each have proximally a finger base (5) which is held in guides (6) of the guide plate (3), which functional gripper head (1) further comprises a finger drive plate (7) which is rotatable relative to the guide plate (3) and a surface of which is provided with a spiral-shaped gear (19) which is compatible with a gear (18) on the finger base (5) so that rotation of the finger drive plate (7) induces a movement of the gripper finger (4) in the guide plate (3), which functional gripper head (1) further comprises a base body (8) and wherein the base body (8) can be connected to the guide plate (3) and to the robot arm (2), wherein the functional gripper head (1) has a fixed segment (9) and has a removable segment (10), which are connected releasably to each other, wherein the removable segment (10) comprises at least the guide plate (3) and the gripper fingers (4).

Description

Robot arm with gripper

The invention relates to a functional gripper head of the robot arm.

Robot arms, also referred to hereinafter as robots, are used for many purposes. The use of robots for performing repetitive tasks has been known for years. It is particularly when large volumes are manufactured, and when predetermined movements of predetermined objects must thus be performed repetitively, that a robot is highly suitable. The gripper head of the robot is then adapted to perform the specific task, after which the robot can be utilized.

A robot is less suitable for limited volumes and for assisting in limited or short-term productions. This is because the cost price of setting and adapting the robot to new movements and new objects to be handled is labour-intensive, time-consuming and costly. Manipulations of workpieces for limited volumes are therefore often performed manually, by hand.

The invention has been developed particularly for robot arms for loading and unloading lathes and/or CNC machines, also referred to hereinafter as CNC-controlled machine tools. When loading a CNC-controlled machine tool, a workpiece, which is typically unprocessed or preprocessed, is taken up by the gripper head of the robot from a supply device and placed in the CNC-controlled machine tool. When the CNC-controlled machine tool has carried out its processes, the workpiece is removed from the CNC-controlled machine tool again by the robot arm and placed on a set-down stack. A new workpiece can then be placed in the CNC-controlled machine tool. This process can be repeated cyclically.

The object of the invention is to be able to switch quickly and easily from one type of workpiece to another type of workpiece, wherein the workpieces can have varying dimensions and shapes. This makes it possible also to use a robot arm when only small production numbers need be produced. This enables a CNC-controlled machine tool to be loaded and unloaded automatically for small production numbers as well.

It is an object of the invention to provide a functional gripper head for a robot which can take hold of workpieces of varying sizes and shapes in reliable manner.

The invention provides for this purpose a functional gripper head for a robot arm, which functional gripper head comprises a guide plate with gripper fingers, which gripper fingers each have proximally a finger base which is held in guides of the guide plate, wherein the guides are preferably linear guides extending in a radial direction, this being a direction perpendicularly of the rotation axis, which functional gripper head further comprises a finger drive plate which is rotatable relative to the guide plate and a surface of which is provided with a spiral-shaped gear which is compatible with a gear on the finger base so that rotation of the finger drive plate induces a movement of the gripper finger in the guide plate, which functional gripper head further comprises a base body and wherein the base body can be connected to the guide plate and to the robot arm, wherein the functional gripper head has a fixed segment and has a removable segment, which are connected releasably to each other, wherein the removable segment comprises at least the guide plate and the gripper fingers.

The invention is based on the insight that a functional gripper head for a robot arm can be constructed with a fixed segment and a removable segment. The removable segment comprises the guide plate and gripper fingers. The guide plate and gripper fingers together determine the gripper configuration. A guide plate can thus be provided with two gripper fingers which are placed close together for the purpose of gripping narrow objects. Two gripper fingers can also be placed at a greater mutual distance in order to clamp wide objects. As a further alternative, a guide plate can be provided with three guides which lie rotated through 120 degrees relative to each other, such that round objects can be clamped by the gripper fingers in simple and centred manner. In the latter stated configuration the gripper fingers can be placed close to a centre of the guide plate or can be placed further away from the centre in order to clamp respectively smaller or larger objects. Different configurations can be envisaged depending on the shape and size of the objects to be manipulated.

The construction of the functional gripper head allows the removable segment to be removed and replaced with a different compatible removable segment. This allows extremely rapid conversion of the functional gripper head of the robot. In other words, a first removable segment can be optimized for round workpieces, while another removable segment is optimized for rectangular workpieces. The construction of this functional gripper head allows an extremely rapid change-over. A further advantage of the construction of the functional gripper head according to the invention is that the operation is reliable and the components are relatively inexpensive. The gripper fingers are moved, preferably linearly in the radial direction, in the guide plate by rotation of the finger drive plate. Complex cams, levers, transmissions, toothed wheels and other complicated dynamic constructions are thus unnecessary.

The fixed segment preferably comprises at least the base body. The base body preferably comprises a frame with a drive element which is provided on one side to be connected at the position of the robot arm to a motor and which is provided on the other side to be connected to the finger drive plate.

In connected state the drive element preferably engages on the finger drive plate in order to rotate the finger drive plate relative to the guide plate.

The drive element and the finger drive plate preferably have at least one complementary pin and hole so that the pin engages in the hole in the connected state in order to drive the finger drive plate via the drive element.

The fixed segment and the removable segment preferably comprise complementary connecting means, such that in connected state the finger drive plate is surrounded by the base body and the guide plate, and that in connected state the gripper fingers engage with their gear in the spiral-shaped gear of the finger drive plate.

The complementary connecting means preferably allow a coupling and uncoupling in the axial direction of the fixed and removable segment.

The base body preferably comprises a pneumatic actuator for locking and unlocking the complementary connecting means.

The finger drive plate is preferably held in the removable segment.

The frame and the guide plate preferably have at least one complementary pin and hole so that the pin engages in the hole in the connected state in order to position the guide plate relative to the frame.

The functional gripper head preferably comprises at least two removable segments, each with a different configuration of guide plate and gripper fingers.

The invention will now be further described on the basis of an exemplary embodiment shown in the drawing.

In the drawing: figure 1 shows an exploded view of a functional gripper head according to an embodiment of the invention; figure 2 shows an exemplary embodiment of a fixed and removable segment of the functional gripper head; figure 3 shows a plurality of possible configurations of a guide plate; figure 4 shows a section of the guide plate; figure 5 shows a section of an embodiment of the functional gripper head; figure 6 shows a further embodiment of the functional gripper head; and figure 7 shows a section of a further preferred embodiment of the functional gripper head.

The same or similar elements are designated in the drawing with the same reference numeral.

Figure 1 shows a functional gripper head 1 , wherein different components are shown spaced apart. The figure further shows a robot arm 2. A robot arm 2 is typically constructed with a base on which a plurality of arm parts are connected rotatably to each other. A robot arm can be supplied in different configurations and sizes. The functional gripper head 1 according to the invention is particularly developed and configured to be connected to a distal end of a robot arm, also referred to as the end effector. The functional gripper head then determines the functions the robot arm is able to perform.

By moving the robot arm the functional gripper head 1 is moved in the space from a position A to a position B along a predetermined path. By manipulating the functional gripper head 1 as will be discussed in detail below the robot arm 2 can transport workpieces from position A to position B with functional gripper head 1. More specifically, a workpiece can be fixedly clamped at position A, after which the robot arm travels the predetermined path, and the clamped workpiece can then be released at position B. This allows automatic loading and unloading of a CNC- controlled machine tool. Unprocessed or preprocessed workpieces can be carried from a first position to the CNC-controlled machine tool by a robot with functional gripper head. When the CNC-controlled machine tool has carried out its processes, the robot arm can grip the processed workpiece at the CNC-controlled machine tool and carry it to a set-down position.

The functional gripper head 1 has a base body 8 which is connected fixedly to the distal end of robot arm 2. Base body 8 thereby forms the fixed segment 9 of the functional gripper head 1. Functional gripper head 1 further has a removable segment 10. The removable segment 10 has a plurality of gripper fingers 4 which are movable in a radial direction relative to a guide plate 3. For this purpose the gripper fingers 4 each have a finger base 5 which is guided in linear guides 6. Linear guides 6 extend in the radial direction. The radial direction is the direction which is perpendicular to the central axis or at least runs away from the central axis. The bases 5 of gripper fingers 4 further have teeth and/or grooves 18. These teeth and/or grooves 18 are compatible with a spiral-shaped gear 19 which is provided on finger drive plate 7.

The finger drive plate 7 is formed as a disc with a drive side and a functional side. The functional side is the side of the disc which comprises the spiral-shaped gear and which is directed toward gripper fingers 4. When the gear of gripper fingers 4 engages on the spiral-shaped gear of finger drive plate 7, rotation of the latter will induce a movement of gripper fingers 4. The skilled person will appreciate here that gripper fingers 4 are held with their finger base 5 in guide plate 3 by guide 6 and are hereby movable in only one direction, the radial direction. The direction of movement is determined by the linear guide 6 which extends in the radial direction.

In figure 1 a combination of guide plate 3, gripper fingers 4 and finger drive plate 7 is designated as removable segment 10. The skilled person will appreciate that, in an alternative configuration, finger drive plate 7 can be connected and integrated in base body 8. In the latter stated configuration guide plate 3 and the gripper fingers will together form the removable segment 10. Base body 8 and finger drive plate 7 will then form the fixed segment 9. In the following description the finger drive plate 7 will form part of the removable segment 10. It will however be apparent to the skilled person that a similar construction with similar advantages can be obtained when finger drive plate 7 is integrated in fixed segment 9.

Figure 2 shows an embodiment of the connecting sides of fixed segment 9 and removable segment 10. Figure 2A shows here an embodiment of the connecting surface of fixed segment 9, and figure 2B shows the connecting surface of a removable segment 10 which is compatible therewith. Figure 2A shows the base body 8 which is formed as a substantially cylindrical housing. Provided in this housing is a drive element 12. Further provided in this cylindrical housing is a connecting means 13 for connecting fixed segment 9 to removable segment 10. Base body 8 is provided to be connected fixedly to the distal end of robot arm 2. Provided in base body 8, or in the distal end of robot arm 2, is a motor. This motor is connected to drive element 12 in order to rotate the drive element 12 relative to base body 8. In figure 2 A connecting means 13 extends axially, such that connecting means 13 can extend at least partially in a cavity or opening or recess of the removal segment. Connecting means 13 further comprises radial locking elements 20, the operation of which will be further elucidated below.

Figure 2B shows the connecting side of removable segment 10. Removable segment 10 comprises the guide plate 3, a rear side or connecting side of which is shown in figure 2B. Guide plate 3 is provided to be connected to base body 8. For this purpose base body 8 has three pins 14 and guide plate 3 has three corresponding holes 15. When pins 14 engage in holes 15, rotation of guide plate 3 relative to base body 8 will be prevented.

Figure 2B further shows the drive side of drive plate 7. In this embodiment finger drive plate 7 has two holes 15 which are compatible with two pins 14 on the drive element 12 of fixed segment 9. When pins 14 of the drive element engage in the holes 15 of the finger drive plate, rotation of finger drive plate 7 relative to drive element 12 will be prevented. The skilled person will appreciate that, by connecting base element 8 to guide plate 3 on the one hand and connecting drive element 12 to finger drive plate 7 on the other, rotation of the drive element relative to base plate 8 also induces a rotation of the finger drive plate relative to the guide plate.

Removable segment 10 further has a recess with an edge, which forms the connecting means 13 which is compatible with the connecting means 13 of fixed segment 9. By placing the protruding connecting element 13 of fixed segment 9 in the recess of removable segment 10 the radial locking elements 20 can prevent undesirable release of removable segment 10 from fixed segment 9. Reference numeral 13 is used in figures 2A and 2B to designate compatible locking means. The skilled person will appreciate that the compatible locking means as shown in figures 2A and 2B comprise an actuator. In the exemplary embodiment of figure 2 the actuator is provided behind the radial locking elements 20 so as to move them in radial direction. The actuator is placed on base body 8 such that the actuator for the locking is controllable from the robot arm. This allows the robot arm 2 to lock and unlock the fixed and removable segment of the functional gripper head. It thus becomes possible for a robot arm to set down one removable segment, this by unlocking the connection, move to a different removable segment and couple or connect this removable segment to fixed segment 9. A functional gripper head having an interchangeable distal segment is thus obtained. This allows distal segments to be formed with a plurality of configurations, as shown below in figure 3. The radial locking elements are preferably moved via compressed air. Figure 2 shows five pins and holes. It will be apparent that this is only one embodiment. One pin and hole combination suffices to prevent rotation of an element on the fixed segment relative to an element on the removable segment. At least two are preferably provided in order to avoid internal stresses.

Figure 3 shows the functional side of the removable segment of functional gripper head 1. The functional side is the side which can be used by robot arm 2 to grip workpieces. The functional side of functional gripper head 1 is constructed similarly to a chuck. A chuck has a surface and a plurality of gripper fingers 4 extending upward from the surface. The surface is usually disc shaped and in the embodiment of figure 3 is formed by guide plate 3. Gripper fingers 4 have a direction of finger movement 16 which typically extends in the radial direction relative to guide plate 3. Each of the gripper fingers 4 can hereby be moved to and from a central point of guide plate 3. As a result, the distance between the gripper fingers will increase or decrease so that a workpiece can be clamped between the gripper fingers.

In figure 3A the guide plate 3 has one linear guide 6 which extends in figure 3A from top to bottom over the whole guide plate 3. Gripper fingers 4 each have a finger base 5. In the embodiment of figure 3 A the gripper fingers are positioned with a small mutual finger distance 17 on finger base 5. Narrow or small workpieces can hereby be clamped between gripper fingers 4. Figure 3B shows a similar guide plate 3 with a similar linear guide 6. In the embodiment of figure 3 the gripper fingers 4 are placed on similar finger bases 5. Gripper fingers 4 are however positioned with a considerably greater finger distance 17 than in the embodiment of figure 3 A. The workpieces which can be handled with the configuration of figure 3B are hereby considerably larger than the workpieces which can be handled with the configuration of figure 3A.

The skilled person will appreciate that each gripper finger has a maximum reach. The reach of the gripper finger is the difference in distance between its most inward position and its most outward position. This reach is determined by the length of finger base 5 and the space for movement that finger base 5 has in linear guides 6. The reach is also determined by the size of the spiral-shaped gear and the position of the teeth and grooves 18 on finger base 5. The plurality of configurations as shown in figure 3A and figure 3B can be chosen so as to clamp with a first configuration, for instance the configuration of figure 3 A, objects with dimensions lying within a first range, for instance 1 cm - 6 cm. A second configuration, for instance the configuration of figure 3B, can then be provided to clamp workpieces with dimensions within a second range, for instance 5 cm - 10 cm. The first range and second range will preferably slightly overlap and largely supplement each other. The skilled person will appreciate that further configurations can be provided wherein the gripper fingers are placed even further apart in order to clamp workpieces having even greater dimensions. Figure 3C shows a further possible configuration of a removable segment 10. In figure 3C three linear guides 6 are provided in guide plate 3, each lying spaced 120° apart. The configuration of figure 3C is provided for the purpose of clamping round workpieces. In figure 3C gripper fingers 4 are formed as upright rods. Each finger basis has two such finger rods. The skilled person will appreciate that this is only one configuration, and that alternative configurations can be provided wherein the gripper fingers are block-shaped, round, provided in single form or provided in double form. The skilled person will appreciate that, similarly to figure 3 A and figure 3B, the position of the gripper fingers on base bodies 5 can also be changed in the configuration of figure 3C in order to be able to handle workpieces within different ranges of dimensions.

A plurality of removable segments 10 with different configurations are preferably provided in robot arm 2. This allows robot arm 2 to connect the removable segment 10 which is best suited for handling the workpiece to be handled to the fixed segment 9. This considerably increases the flexibility of the robot arm and, more specifically, the options for the robot arm of being able to clamp a wide variety of workpieces without the intervention of an operator.

Figure 4 shows a cross-section B-B of a guide plate 3 as designated in figure 3C. Figure 4 shows that linear guide 6 holds the finger base 5. In other words, guide plate 3 is compatible in shape in cross-section with the base 5 of the gripper finger, such that base 5 is held in guide plate 3 and is movable only in the longitudinal direction of guide 6. Figure 4 further shows the finger drive plate 7 having a spiral-shaped gear 19. Finger base 5 also has a gear 18 which engages in the spiral-shaped gear 19. The finger base 5 will be moved in the linear guide 6 by the rotation of the finger drive plate 7. Gripper fingers 4 will hereby perform the finger movement 16.

Figure 5 shows a section along the central axis of the functional gripper head. In figure 5 the fixed segment is connected to a removable segment. Figure 5 shows that frame 11 is connected via a pin-hole 14/15 to a rear side 3 a of guide plate 3. The figure further shows that drive element 12 is connected to a motor 21 on one side and is connected via pin-hole 14/15 to finger drive plate 7.

Figure 5 further shows that connecting means 13 engage in each other. The removable segment has recess 13a which comprises a flange at the location of the fixed segment. The fixed segment, in this embodiment the drive element 12 thereof, has an axial protrusion with radial locking elements 13b. The radial locking elements are elements which can be moved in radial direction, as indicated with arrow 20. By moving radial locking elements 13b outward the radial locking elements 13b will engage behind the flange of recess 13a. An axial movement, designated with arrow 22, of the removable segment relative to the fixed segment is hereby prevented. In other words, the removable segment will hereby be connected to the fixed segment. By retracting radial locking elements 13b the removable segment can be moved from the fixed segment as according to arrow 22. Figure 5 further shows that guide plate 3 holds the finger base 5 with gripper fingers 4. Gripper fingers 4 have a finger distance 17. The finger drive plate 7 provided with the spiral shaped gear 19 is behind finger base 5. Teeth of finger base 5 engage in the spiral-shaped gear, all this such that rotation of drive plate 7 results in a movement of gripper fingers 4. Gripper fingers 4 can thus be moved apart and moved toward each other in order to respectively release and fixedly clamp workpieces.

Figure 6 shows a preferred embodiment of a functional gripper head according to the invention which takes a double form. The functional gripper head of figure 6 is designated with reference numeral and is shown at a distal end of a robot arm 2. Functional gripper head has two removable segments 10a and 10b. These removable segments 10a and 10b are placed on a central fixed segment 9’ . Specifically for the purpose of loading and unloading a CNC-controlled machine tool, this configuration allows a first removable segment with a configuration which is optimized for gripping a workpiece to be processed to be provided on one side, and a removable segment with a configuration which is optimized for gripping a processed workpiece to be provided on another side. By constructing each of the two removable segments as described above, two production pieces can be switched between in rapid, simple and automatic manner.

Figure 7 shows an alternative preferred embodiment of a section along the central axis of the functional gripper head. In figure 7 the fixed segment 9 is shown at a distance from the removable segment 10. Figure 7 shows that frame 11 is connected via the radial locking element 20 to guide plate 3. A pin-hole connection or other shape compatibility which prevents frame 11 from rotating relative to guide plate 3 is preferably additionally also provided on the radial locking element 20. The figure further shows that drive element 12 is connected to a motor 21 via a toothed wheel 23. On the other side, drive element 12 is provided to be connected via pin-hole 14/15 to the finger drive plate 7.

Figure 7 shows connecting means which are substantially identical to the connecting means of figure 5. For the description hereof reference is made to the above. In this embodiment the drive of the radial locking element is embodied by a locking element 25 which can be moved forward and rearward via compressed air 24. Figure 7 further shows that guide plate 3 holds the finger base 5 with gripper fingers 4 in similar manner as in figure 5, and reference is made to the explanation above.

The skilled person will appreciate on the basis of the above description that the invention can be embodied in different ways and on the basis of different principles. The invention is not limited to the above described embodiments. The above described embodiments and the figures are purely illustrative and serve only to increase understanding of the invention. The invention will not therefore be limited to the embodiments described herein, but is defined in the claims.

Claims

1. Functional gripper head for a robot arm, which functional gripper head comprises a guide plate with gripper fingers, which gripper fingers each have proximally a finger base which is held in guides of the guide plate, which functional gripper head further comprises a finger drive plate which is rotatable relative to the guide plate and a surface of which is provided with a spiral shaped gear which is compatible with a gear on the finger base so that rotation of the finger drive plate induces a movement of the gripper finger in the guide plate, which functional gripper head further comprises a base body and wherein the base body can be connected to the guide plate and to the robot arm, wherein the functional gripper head has a fixed segment and has a removable segment, which are connected releasably to each other, wherein the removable segment comprises at least the guide plate and the gripper fingers, wherein the functional gripper head comprises at least two removable segments, each with a different configuration of guide plate and gripper fingers.

2. Functional gripper head according to claim 1, wherein the fixed segment comprises at least the base body.

3. Functional gripper head according to claim 1 or 2, wherein the base body comprises a frame with a drive element which is provided on one side to be connected at the position of the robot arm to a motor and which is provided on the other side to be connected to the finger drive plate.

4. Functional gripper head according to the foregoing claim, wherein in connected state the drive element engages on the finger drive plate in order to rotate the finger drive plate relative to the guide plate.

5. Functional gripper head according to the foregoing claim, wherein the drive element and the finger drive plate have at least one complementary pin and hole so that the pin engages in the hole in the connected state in order to drive the finger drive plate via the drive element.

6. Functional gripper head according to any one of the foregoing claims, wherein the fixed segment and the removable segment comprise complementary connecting means, such that in connected state the finger drive plate is surrounded by the base body and the guide plate, and that in connected state the gripper fingers engage with their gear in the spiral-shaped gear of the finger drive plate.

7. Functional gripper head according to the foregoing claim, wherein the complementary connecting means allow a coupling and uncoupling in the axial direction of the fixed and removable segment.

8. Functional gripper head according to the foregoing claim, wherein the base body comprises a pneumatic actuator for locking and unlocking the complementary connecting means.

9. Functional gripper head according to any one of the foregoing claims, wherein the finger drive plate is held in the removable segment.

10. Functional gripper head according to any one of the foregoing claims and claim 3, wherein the frame and the guide plate have at least one complementary pin and hole so that the pin engages in the hole in the connected state in order to position the guide plate relative to the frame.

11. Robot arm with a functional gripper head according to any one of the foregoing claims.