Manipulator-guided gripping device having a deflection safety device that can prevent collisions
A manipulator-guided gripping device (1) for motor vehicle body parts includes a number of device parts (6, 7) and a safety device (9), which serves to determine geometrical changes of the device parts (6, 7, 8). At least one deflection safety device (10), which prevents collisions, is provided on the device parts (6, 7, 8). The deflection safety device (10) is mounted on a junction point (23) between the device parts (6, 7, 8).
This application is a United States National Phase application of International Application PCT/EP2004/006113 filed Jun. 7, 2004 and claims the benefit of priority under 35 U.S.C. § 119 of German Application DE 203 09 435.2 filed Jun. 17, 2003 and DE 203 14 896.7 filed Sep. 24, 2003, the entire contents of which are incorporated herein by reference.
FIELD OF THE INVENTIONThe present invention pertains to a manipulator-guided gripping device for workpieces, especially body parts in the body shell, wherein the gripping device has a plurality of device parts and a safety means for detecting changes in geometry.
BACKGROUND OF THE INVENTIONSuch a gripping device for vehicle body parts in body framing and paneling is known from DE 200 04 369 U1. The gripping device is guided by a multiaxial industrial robot. Such devices are used in partially or fully automatic plants or cells for body framing and paneling or in other technical areas. Collisions and crashes may occur here, in which the gripping device may be damaged. Such damage leads mostly to a change in geometry. For example, gripping parts that are relevant for function or the component, for example, tensioners, grippers, alignment pins or shearing pins, centering pins or the like may now be bent, twisted or brought out of their desired position in another way. This may also happen due to deformation of the gripper frame. Crashes are recognized and reported in practice by monitoring the motor current of the robot axis drives. However, this operates reliably only in case of violent collisions, which propagate to the robot drive. Minor collisions with weaker forces, which are mostly absorbed extensively by the yielding of the gripping device or parts thereof, cannot be recognized by monitoring the motor current. However, such minor collisions nevertheless lead to damage to and malfunction of the gripping device, which in turn entails errors in the machining process and on the body shell. In case of the above-mentioned major collisions, which are detected and signaled by monitoring the motor current, the gripping device is replaced and repaired. The gripping device must be removed to identify and repair the unknown damage, set up completely and remeasured. This is a very complicated operation and can be carried out only outside the gripper operation.
SUMMARY OF THE INVENTIONAn object of the present invention is to provide a gripping device that exhibits better behavior in case of crashes and collisions.
According to the invention, a manipulator-guided gripping device is provided for workpieces such as body parts in a body shell. The gripping device has a plurality of device parts and a safety means for detecting changes in geometry with at least one deflectable safety device at the device parts. The deflectable safety device is provided at the various components or parts of the gripping device. The safety device is preferably present as multiple devices to provide the advantage that it makes possible the deflection of the colliding parts of the gripping device in case of a crash or collision, as a result of which plastic deformations and other damage are avoided on the gripping device. Due to the deflected position, it is, moreover, optically signaled to an operator that a collision has taken place. In addition, suitable detectors or sensors may be present at the deflectable safety device, which detect a deflecting movement and report it in a suitable manner, for example, signal it to a process control, automatically trigger an alarm or the like.
The deflectable safety device is preferably arranged at a connection point between the different device parts of the gripping device. The device parts, for example, frame tubes, may also be divided, in which case a deflectable safety device is arranged between the tube sections. The deflectable safety device may be located as a result at the points of the gripping device that have been shown by experience to be loaded most heavily and are also critical. Depending on the geometry of the gripping device, the positions of the different deflectable safety devices are selected to be such that the colliding device part can be deflected immediately in case of a collision, and deformations and damage are avoided in this part as well as on the other components of the gripping device.
The deflectable safety device may connect the device parts with clamping and frictional connection or with deflectable positive-locking connection. An adjusting means makes possible the reproducible positioning of the device parts in the initial device and also during the repositioning after a crash. The detector may be a part of the adjusting means. The moving device part can again be returned into its desired position after the deflection. As a result, the gripping device can continue to be used without complicated measurement and resetting.
If the deflectable safety device is provided with a locking element for positive-locking guiding, it is thus also possible to exactly define the desired position and to position the device parts. The locking element is preferably spring-loaded, and the overload or load threshold generated by collision, beginning from which deflection is to take place, can be set by means of the spring mounting. The deflectable safety device is rigid and dimensionally stable below this threshold, so that it does not compromise the function and the geometry of the gripping device. The holding frictional force can be set by a controlled clamping connection in case of a frictionally engaged connection.
From a design viewpoint, the deflectable safety device may have various designs. It preferably comprises at least two safety device parts, which may be designed, for example, as a sphere each with a socket surrounding it or as disk mounts with parallel working surfaces. A plurality of locking elements, which may be designed, for example, as spring-loaded balls or the like, are preferably located between the safety device parts. By selecting the geometry of the safety device parts and of the locking elements correspondingly, the deflectable safety device can make possible deflection along one or more defined axes in case of a collision.
The present invention is schematically shown in the drawings as an example. The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated.
BRIEF DESCRIPTION OF THE DRAWINGSIn the drawings:
Referring to the drawings in particular,
The gripping device (1) is designed, for example, as a so-called geogripper, in which all device parts (6, 7, 8) have an exactly defined position and orientation. The geogripper is exactly adapted to the geometry of the workpiece to be manipulated.
The gripping device (1) has a safety means (9), which responds in case of a crash and collisions with the external environment. The safety means (9) has at least one, preferably a plurality of deflectable safety devices (10), which are arranged at the device parts (6, 7, 8) and permit the deflection thereof in case of a collision. The deflectable safety devices (10) are arranged at a junction point (23) between the device parts (6, 7, 8).
Such junction points (23) are, for example, the connection points at which the device parts (6), i.e., the tensioners, grippers, component centering means or the like are connected to the frame (4). The deflectable safety device (10) is arranged here between the device part (6) and the frame (4). Other junction points (23) with a deflectable safety device (10) are located at the points of intersection of the frame tubes (7, 8), where these are connected to one another. On the other hand, one or more frame tubes (7, 8) may also be divided, in which case two, preferably aligned tube sections (7′, 7″) are arranged at the junction or junction point (23) at the deflectable safety device (10). Such divisions of the tube may be present at the points of the gripping device (1) that experience has shown to be subject to higher loads and are located, for example, at the tube sections projecting away from the docking plate (5). It is possible in another variant to provide the connection points between the frame (4) or the frame tubes (7, 8) with the docking point (5) with deflectable safety devices (10).
The deflectable safety devices (10) are rigid and dimensionally stable during normal operation. They withstand all the static and dynamic loads occurring during normal operation. The deflectable safety device responds only when a collision of the gripping device (1) with an obstacle occurs and collision forces or overload develops, and the deflectable safety device now permits the deflection of the colliding device part (6, 7, 7′, 7″, 8).
The deflectable safety device (10) comprises at least two safety device parts (11, 12), which are mounted at each other such that they can be deflected in case of overload. The safety device parts (11, 12) may be connected by positive-locking connection as in the variants according to
The positive-locking deflectable safety devices (10) according to
The locking element (13) is located between the safety device parts (11, 12). The safety device parts (11, 12) are in turn connected to a device parts [sic—Tr.Ed.] (6, 7, 8). This connection is exactly defined geometrically and can be set exactly, for example, by means of positioning pins (29), shearing pins or the like. The safety device parts (11, 12) can likewise be positioned exactly in relation to one other by means of the locking elements (13) and are secured and held in their positions by the locking element (13) and/or the clamping element (20). The force of the clamping element (20) can be set and is adjusted in the above-mentioned manner to the static and dynamic forces acting during normal operation. The safety device parts (11, 12) yield in relation to one another only when a force threshold, which may optionally be set with a safety margin, is exceeded. The deflecting movement may take place along one or more axes depending on the embodiment of the safety device parts (11, 12) and of the locking element (13).
In the variant according to
The socket (14) and the joint ball (15) are held in contact with one another by the locking element (13), which comprises in this case a plurality of locking balls (18), which are distributed on the circumference in the contact area and are acted on by a pressing spring (22) each as a clamp, tensioner or clamping element (20). The locking balls (18) engage correspondingly shaped, exactly defined mounts (19) at the socket (14) and the joint ball (15) and thus secure the connection. Such ball/spring units may be screwed as ready-made machine parts into the socket (14). At least three, preferably four locking balls (18) are arranged in a uniformly distributed manner over the circumference of the ball on a line at right angles to the longitudinal axis of the tube section.
When, for example, an upsetting or tensile force develops along the central axis of the two, preferably aligned tube sections (7′, 7″), the tube section (7″) with the joint ball (15) can be pulled out of or pushed into the socket (14) when the force acting is greater than the resultant, acting in the same direction, from the holding force of the radially acting springs (22). The socket (14) has a sufficient clearance at the bottom against the joint ball (15) to absorb upsetting forces and upsetting movements. If, on the other hand, lateral forces act on one of the tube sections (7′, 7″), the joint ball (15) can rotate correspondingly in the socket (14) about the vertical and/or horizontal axis for deflection. Torsional forces can also be absorbed by a deflecting movement and rotation about the longitudinal axis of the tube.
The mounts (19) may be designed with precision such that they permit the ball (18) to snap in only when it is in the exact position. As a result, a deflecting movement in case of collision is not abolished and returned by itself. The device parts (6, 7, 8) stop in the deflected position in relation to one another. The desired position and the locked position can, however, be restored by an operator by manual engaging. As soon as all locking balls (18) engage their respective mounts (19), the desired position is exactly restored.
As an alternative, the mounts (19) may have an expanded shape at one of the safety device parts, for example, the joint ball (15), and form, for example, recesses or pans (28) with an enlarged radius of curvature. In case of such a shape or another suitable shape, the deflecting device part (6, 7, 7′, 7″, 8) can snap back by itself into the desired position after the collision.
As is also illustrated in
According to
In the variant according to
The clamping element (20) is designed in this variant as a tightening screw (21) with a spring (22), which extends centrally and at right angles through the ball ring. It extends in two aligned mounting holes of the disk mounts (16, 17). The mounting holes have a larger diameter than the shaft of the screw, which is guided at the ends of the hole by half shell-shaped insert elements, which are in contact with the screw head, on the one hand, and with the spring (22), on the other hand. The two disk mounts (16, 17) are connected to the tube sections (7′, 7″) by corresponding metal fittings (27) in a geometrically defined position.
Possibilities of deflection along the four axes explained in the exemplary embodiment according to
Detectors (24) of the above-described type may likewise be present in the deflectable safety device (10) according to
The two safety device parts (11, 12) of the deflectable safety device (10) are of a similar design in the three variants, there being a positive-locking guiding with a spring-loaded locking element (13) in the exemplary embodiment according to
One safety device part (12) is provided with the sphere as a ring-shaped collar (15′) with an outer edge rounded in a spherical form in the three variants. The collar (15′) is connected to the shaft (37) and is preferably made in one piece with it. The spherical rounding has the shape of a spherical segment, whose center (40) is the intersection of the central shaft axis (38) with the central plane of the ring collar (15′), which said central plane is located at right angles.
The second safety device part (11) is connected to the frame tube (8) or another device part in a suitable manner, e.g., by a clamp-like metal fitting (27) with exact positioning and optionally a positioning pin (29). The safety device part (11) has a socket, which is designed as a ring-shaped calotte (14′) and has an inner side rounded in a complementary and spherical manner. The rounding is designed as a spherical segment surface with the center (40) in this case as well. Due to this design, the safety device parts (11, 12) can rotate with their device parts (6, 8) about the center (40) in the manner indicated by arrows in
To make it possible to mount the safety device parts (11, 12), the calotte (14′) has a multipart design and comprises, e.g., two shell parts (30, 31), which meet at a transverse plane extending through the center (40) and can be connected and tightened by means of screws (32). Ground fitting plates are inserted at the contact point for an exact fit. This embodiment is again the same in the three embodiments according to
A locking element (13) is present in the variant according to
There is no locking element (13) in the two variants according to
Another adjusting means (33) is present in the embodiments according to
In the variant according to
A second adjusting screw (34) is arranged in a projection (39) of the safety device part (11) having a C-shaped cross section in the design according to
The width of the spherical ring collar (15′) and of the calotte (14′) can be set differently as needed and according to the desired deflection behavior. The widths are preferably essentially equal in the exemplary embodiments being shown, the calotte (14) being able to be somewhat wider on both sides than the collar (15′). The resistance during deflection is determined by the ratio of the widths. The calotte (14′) and the ring collar (15′) may become disengaged in some areas during deflection in case of a small width, as a result of which the section modulus counteracting the deflection is reduced. The consequence of this is a faster and easier deflection, as a result of which deformations or other damage to the device parts (6, 7, 8) due to overload can be prevented from occurring.
A detector (24) is likewise present in the deflectable safety device (10) according to
The detector (24) has a microswitch or sensor (48), which is arranged in the projection (39) in the central axis (38) and comes into switching contact with the tip of the head part (45). In case of collision and deflection, the pressure piece (44) can yield elastically and become separated from the socket (47), while the microswitch (48) is actuated. The microswitch (48) may be of any desired technical type and design and is also not limited to the typical mechanical microswitches.
The microswitch (48) is guided movably along the axis (38) in a housing opening (51) and is acted on from the underside with a spring device (49), e.g., a compression spring, especially a plate spring assembly. The spring device (49) is supported at a laterally projecting collar of the microswitch (48). The microswitch (48) is acted on from the top by a clamping cover (50) in an adjustable manner against the force of the spring device (49). By actuating the tightening screws, the clamping cover (50) can be moved up and down along the axis (38). The detector (24) and the elastic pressure piece (44) can thus be set exactly in relation to one another. The microswitch (48) can then be closed in the determined position and secured against undesired adjustment.
In this design, the detector (24) with its elastic pressure piece (44) is part of the adjusting means (33) operating in a positive-locking manner. This design has advantages in terms of manufacturing technology and signal engineering. The sensitivity with which the adjusting means (33) is triggered and also the sensitivity of switching of the detector (24) can be set and optimized by selecting the pretension of the spring. In addition, the design effort is reduced compared with the other exemplary embodiments.
The deflectable safety device (10) according to
Various variants of the embodiments shown are possible. This applies, on the one hand, to the arrangement and the positioning of the deflectable safety devices (10) at the gripping device (1). The gripping device (1) may have, besides, a different geometric design and comprise other device parts (6, 7, 8). The frame (4) may be, in particular, plate-shaped or have another solid design.
Furthermore, the design embodiments of the deflectable safety device (10) and the parts (11, 12, 13) thereof may be modified as well. For example, more than two safety device parts (11, 12) may be present in intersections. The locking element (13) may comprise, as an alternative, one or more geometrically defined, stationary stops at the safety device parts (11, 12), against which the respective other safety device part is pressed with a predetermined force. The triggering force may be able to be set in this case as well. In another variant, the locking element (13) may have shearing pins, which engage corresponding mounts (19), instead of one or more locking balls (18). The shearing pins consist of a suitable material, which breaks at a defined overload and thus makes possible a mutual deflection of the safety device parts (21, 22) while the positive-locking connection is abolished.
The design embodiment of the deflectable safety devices (10) may, moreover, be selected to be completely different by using, for example, electric buttons or sensors, which detect and report overload forces when collisions occur, but deflection of a device part (6, 7, 8) does not occur. Furthermore, it is possible to operate with electric, pneumatic and hydraulic switch-off safety devices, which function with or without deflecting movement.
Claims
1. A manipulator-guided gripping device for workpieces and body parts in a body shell, the gripping device comprising: a plurality of device parts; a safety means for detecting changes in geometry, including at least one deflectable safety device at the device parts.
2. A gripping device in accordance with claim 1, wherein the deflectable safety device is arranged at a junction point between the device parts.
3. A gripping device in accordance with claim 1, wherein the deflectable safety device has at least two said safety device parts that are mounted such that they can deflect along one or more axes in case of overload.
4. A gripping device in accordance with claim 3, wherein the safety device parts are connected to one another by clamping connection and frictional connection.
5. A gripping device in accordance with claim 3, wherein the safety device parts are connected to one another in a positive-locking manner by at least one said deflectable locking element.
6. A gripping device in accordance with claim 3, wherein the safety device parts are connected to a device part each.
7. A gripping device in accordance with claim 5, wherein the locking element is arranged between the safety device parts.
8. A gripping device in accordance with claim 5, wherein the locking element is held with an elastic clamping element.
9. A gripping device in accordance with claim 8, wherein the locking element and the clamping element are set to a force that holds the safety device parts during normal operation.
10. A gripping device in accordance with claim 1, wherein the safety device parts are designed as a sphere and as a socket surrounding same.
11. A gripping device in accordance with claim 10, wherein the sphere is designed as a joint ball and the socket is designed as a straight tube section.
12. A gripping device in accordance with claim 10, wherein the sphere is designed as a ring-shaped collar with a spherical outer side and the socket is designed as a calotte surrounding same with an inner side rounded in a complementary manner.
13. A gripping device in accordance with claim 12, wherein the collar and the calotte surrounding same have essentially the same width.
14. A gripping device in accordance with claim 3, wherein the safety device parts are designed as disk mounts with parallel working surfaces.
15. A gripping device in accordance with claim 3, wherein the safety device parts have an adjusting means for reproducible mutual positioning.
16. A gripping device in accordance with claim 3, wherein the safety device parts have one or more detectors, which detect and signal deflections of the safety device parts.
17. A gripping device in accordance with claim 16, wherein the detector is arranged eccentrically in relation to the central axis of the safety device parts.
18. A gripping device in accordance with claim 16, wherein the detector is arranged centrally in the central axis of the safety device parts the safety device parts have an adjusting means for reproducible mutual positioning and the detector is designed as a part of the adjusting means.
19. A gripping device in accordance with claim 18, wherein the detector has a pressure piece, which is mounted in an elastically movable manner in an end-side tube section of the shaft and whose projecting head part engages a mount at a projection of the other safety device part in a positive-locking manner, wherein a microswitch is arranged at the contact point.
20. A gripping device in accordance with claim 16, wherein the detectors are connected to a process control.
21. A gripping device in accordance with claim 1, further comprising: a frame with one or more said gripping or clamping elements and with a docking point for connection to a mechanical manipulator in the form of a multiaxial industrial robot.
22. A gripping device in accordance with claim 1, wherein the frame has a plurality of said frame tubes.
23. A gripping device in accordance with claim 15, wherein the frame tubes are divided and wherein a deflectable safety device is arranged between the tube sections.
Type: Application
Filed: Jun 7, 2004
Publication Date: Aug 17, 2006
Inventors: Botho Kikut (Augsburg), Elmar Nuchter (Augsburg)
Application Number: 10/560,875
International Classification: A47G 21/10 (20060101);