Abstract
A gripping device for mechanical fasteners, such as rivets, screws, bolts, and similar fasteners, and a robot effector employing such a device. The device includes a housing and a pair of jaws arranged on a holder. The pair of jaws is adapted to grip a mechanical fastener therebetween. The holder is rotatable inside of the housing and the jaws allow a self-centering of a gripped mechanical fastener.
Claims
1-14. (canceled)
15. A gripping device for mechanical fasteners, such as rivets, screws, bolts, or similar fasteners, the gripping device comprising: a housing; and a pair of jaws arranged on a holder, the pair of jaws adapted to grip a mechanical fastener therebetween; wherein the holder is arranged rotatable inside of the housing (10) and wherein the jaws are shaped to facilitate a self-centering of a gripped mechanical fastener.
16. The gripping device of claim 15, wherein at least one of the jaws has a concave gripping surface that facilitates the self-centering.
17. The gripping device of claim 16, wherein the concave gripping surface comprises one of a V-shaped or U-shaped gripping surface.
18. The gripping device of claim 15, wherein each jaw is arranged on a free end of a lever arm, and wherein the respective lever arms are pivotally supported by the holder.
19. The gripping device of the claim 18, wherein the respective lever arms are supported such that during a pivoting movement of the lever arms, the free ends of the lever arms move toward or away from each other.
20. The gripping device of claim 18, wherein pivot axes of the two lever arms are parallel.
21. The gripping device of claim 20, wherein the pivot axes of the two lever arms are not identical and define a plane that is perpendicular to an axis of rotation of the holder.
22. The gripping device of claim 16, further comprising an actuating piston that actuates the lever arms.
23. The gripping device of claim 22, wherein: at least one of the lever arms comprises an actuating projection that is offset from the pivot axis of the lever; the actuating piston is linearly movable inside the holder and is adapted to interact with the actuating projection; and the actuating piston is arranged such that it rotates with the holder.
24. The gripping device of claim 15, wherein the jaws are actuated pneumatically.
25. The gripping device of claim 15, wherein the holder has a cylindrical hollow shape.
26. A robot end effector for installing mechanical fasteners, such as rivets, screws, bolts, or similar fasteners, the robot end effector comprising: a frame; and a gripping device in accordance with claim 15 supported on the frame.
27. The robot end effector of claim 26, further comprising: a feeder mechanism supported on the frame for feeding mechanical fasteners, to the gripping device; wherein the gripping device is rotatably movable on the frame between a first position where the gripping device grips a mechanical fastener from the feeder mechanism, and a second position where the gripping device provides a gripped mechanical fastener to an installation mechanism.
28. The robot end effector of claim 27, wherein the gripping device is linearly movable on the frame.
29. A robot comprising a robot end effector in accordance with claim 26.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] In the following, the invention is described exemplarily with reference to the enclosed figures, in which:
[0013] FIGS. 1a and 1b show schematic, 3-dimensional drawings of a robot effector comprising a gripping device in accordance with the invention;
[0014] FIG. 2 shows a gripping device in accordance with the invention in an exploded, 3-dimensional view;
[0015] FIG. 3 shows the device of FIG. 2 in a schematic, partially cut 3-dimensional view in assembled condition;
[0016] FIGS. 4a-4c show different cut-views of the device of FIGS. 2 and 3;
[0017] FIGS. 5a and b show a front view of the jaws of the gripping device, and.
[0018] FIG. 6 shows schematically an industrial robot equipped with the effector of FIGS. 1a and 1 b.
DETAILED DESCRIPTION
[0019] In FIG. 1a a robot effector 100 for installing mechanical fasteners, in the shown case of rivets, is shown in a 3-dimensional schematic view. The effector 100 forms part of a larger end effector (not shown) for an industrial robot, which larger end effector can e.g. comprises further installation tools, measurement tools etc. The robot effector comprises a frame 101, that supports a number of work stations necessary for an automatic installation of rivets. The frame 101 comprises a fixing plate 105, which is in use attached to e.g. the larger end effector or the hand of an industrial robot, similar as shown in the figures of the DE 20 2008 014886 U1 discussed above. The frame 101 carries a feeder mechanism 110 for feeding mechanical fasteners. In the shown configuration, three feed lines 102, 103, 104 are provided, through which rivets of different sizes can be transported from a magazine by means of air to the feeder mechanism 110. The feeder mechanism 110 comprises three outlets 111, 112, 113 to provide/present the differently sized rivets. The outlets hold and present the rivets in a desired orientation, such that they can be grabbed by the gripping device 1. The gripping device 1 is likewise mounted on frame 101 and arranged thereon, such that it is rotatable around an axis of rotation 120. Thereby, the gripping device 1 can be rotated to different stations of the effector 100, such as for example to the three different outlets of the feeder mechanism 110. To this end, the three outlets 111, 112 and 113 are arranged on the radius that the gripping device 100 follows, when rotating around axis 120.
[0020] In the shown embodiment, additionally a supply station 130 for additives is provided. The supply station 130 can for example provide glue or sealant fluid to the rivets grabbed by gripping device 1. In practice, the gripping device 1 first rotates until its jaws are aligned with one of the outlets. There, the gripping device is moved linearly towards the outlet, until the jaws of the gripping device can grip one of the supplied rivets. Once gripped, the gripping device 1 is again moved linearly away from the feeder mechanism 110 and then rotated, until the gripped rivet is at the supply station 130. As it will be explained in more detail below, at the supply station the gripped rivet is for example provided with a sealant material. Afterwards, the gripping device 1 is again rotated into the position shown in FIG. 1a, where the rivet is for example provided to further installation tools that may be provided on the same larger end effector as mentioned above.
[0021] FIG. 1b shows the device of FIG. 1a in a 180° rotated view. The robot effector 100 additionally comprises a slide 121 for linear movement of the gripping device 1. Thus, the slide 121 can move the device 1 back and forth, such as for example towards the outlets of the feeder mechanism 110 and away therefrom. Reference number 106 denotes electronic controllers of the effector 100.
[0022] FIG. 2 shows a schematic, 3-dimensional exploded view of the gripping device 1, however, without the housing, to allow a view of the interior parts thereof. The housing 10 is shown in the partially cut 3-dimensional schematic view of FIG. 3, wherein the device of FIG. 2 is shown in assembled condition. Turning back to FIG. 2, one can see a holder 40, having a cylindrical, hollow shape. The holder is arranged rotatable inside of the housing 10, as will be explained below with reference to FIG. 3. Further, the device comprises a pair of jaws 20, 21, that are mounted to the holder 40 via a corresponding pair of lever arms 30 and 31. Each lever arm comprises a free end 32, 33 onto which the jaws 20, 21 are pivotably arranged. Further, a tooth wheel 42 is provided, that is fixedly attached to the holder 40 by means of screws. The holder 40 is rotated via the tooth wheel 42, which in turn is actuated by means of drive wheels 45, 46, which engage the tooth wheel 42. The drive wheels are shown in FIG. 3. Still further, a stop member 23 is provided, which serves the purpose to prevent that gripped fasteners do extend to the actuating portion of the lever arms, so that the movement thereof is not hindered by any gripped fasteners.
[0023] Turning back to the lever arms, each lever arm 30, 31 is supported pivotably by the holder 40 via pivot pins 38, 39 that are arranged in bearings 43. The skilled person will recognize from the illustration of FIG. 2, that the pivot axes of the two lever arms are parallel but are not identical but rather offset at a certain distance from each other. Thus, the two pivot axes of lever arms 30 and 31 define a plane that is perpendicular to the axis of rotation of holder 40. The actuating of the lever arms, i.e. the movement of jaws 20 and 21, is effected by means of an actuating piston 50. The actuating piston 50 runs through the hollow holder 40 and is arranged linearly moveable therein. It comprises a piston pin 51, which interacts with actuating projections 36 and 37 provided on the lever arms. Each actuating projection is offset from the pivot axis of its lever and when the actuating piston 50 is moved back and forth linearly inside of holder 40, the piston pin 51 engages the actuating projections 36, 37, whereby the lever arms 30 and 31 are pivoted around the respective pivot pins 38, 39.
[0024] The device comprises further a cover 60 and a pneumatic connector 62, by means of which pressurized air is supplied in the space behind actuating piston 50, i.e. in the space between cover 60 and actuating piston 50. Thereby, the actuating piston 50 can be moved to the right in FIG. 2. Sealing rings 61 are provided to prevent pressurized air from escaping the housing. A number of return springs 41 push the piston back, once the pressurized air supply is switched off.
[0025] In FIG. 3, the device shown in exploded view in FIG. 2 is shown in assembled condition. One can see how the holder 40 is mounted inside of housing 10. The holder 40 is arranged rotatable in housing 10, by means of the tooth wheel 42, which is driven by drive wheels 45 and 46. When the holder 40 is rotated, also the levers 30, 31 and thereby the jaws 20 and 21 are rotated, whereas the cover 60 remains fixed to housing 10. Due to this rotation, it is possible to rotate a gripped fastener, as for example a rivet 80, as shown in FIG. 3. Thereby, it is possible to move a gripped rivet to the supply station 130 and to rotate rivet 80 at the supply station 130, so that it can be fully covered by for example glue or sealant or similar. The actuating piston 50 can only be moved in one direction by means of the pressurized air. The return stroke of piston 50 is effected by means of return springs 41. The return springs 41 hereby are supported by a baseplate of the piston 50 and directly or indirectly by the holder 40. As FIG. 3 shows a sectional view, also the holder 40 and the tooth wheel 42 are shown in section and therefore, the springs 41 in FIG. 3 have with one side no connection to a part of the gripping device 1. Directly or indirectly can mean, that the return springs 41 can be supported by a surface of the holder 40 itself or by another element, that is connected/to or with the holder 40, for example the tooth wheel 42, which is screwed to the holder 40. Furthermore, in FIGS. 2 and 3 six return springs 41 are shown. However, it is also possible to use more or less return springs 41, especially, two, four, six or eight return springs 41.
[0026] In FIG. 3, one can further see, how jaws 20 and 21 are mounted pivotable to the free ends 32 respectively 33 of the lever arms.
[0027] FIG. 4a shows a partially cut 3-dimensional view, similar to that of FIG. 3, however with a much larger rivet 81 gripped between the jaws 20 and 21. As one can take from the cut views of FIGS. 4a and b, the actuating piston 50 can be moved forward, i.e. to the right in the figures when pressurized air is supplied via connector 62 into the space between cover 60 and piston 50. When piston 50 moves to the right in FIG. 4a, the piston pin 51 interacts with the actuating projection 37 (and actuating projection 36, which is however not visible in FIGS. 4a and b), such that lever arm 31 is rotated anticlockwise around its pivot axis 35. In the shown orientation of FIG. 4a, the lever arm 30 is accordingly rotated clockwise. This has the effect that the jaws 20 and 21 open. A closing of jaws 20 and 21 is accordingly achieved by means of the return springs 41. However, the skilled person will recognize, that depending on the chosen geometry this mechanism could likewise be inversed, such that the jaws 20, 21 close upon supplying pressurized air, and that they open due to the return springs 41. The number of return springs 41 hereby depends on the force that has to or shall be applied on the fasteners and/or jaws 20 and 21 for closing or opening. In the detailed view of FIG. 4a, one can further see where the axis of rotation 120 of the gripping device 130 is in respect to the robot effector 100. Further, one can see a supply line 131 for supplying an additive, such as a sealant to the supply station 130 in order to provide the rivet 81 with a suitable additive. The gripping device 1 is arranged linearly movable parallel to the axis of rotation 120 of gripping device 1 by means of slide 121, so that for example the rivet 81 can be moved back and forth in station 130, in order to provide a larger surface area of rivet 81 with the desired additive.
[0028] FIG. 4b shows basically the same elements as FIG. 4a, however, in a cut side view.
[0029] FIG. 4c shows the same arrangement as FIG. 4b, however with a much smaller rivet 82 gripped by jaws 20 and 21. One can see that piston 50 is moved back almost into contact with the inner surface of cap 60 by means of the return springs 41. Upon pressurizing, the piston 50 will move to the right in FIG. 4c, whereby the upper lever 31 is rotated anticlockwise and the lower lever 30 clockwise so that the jaws opened. The skilled person will understand that the expressions left, right, upper, clockwise etc. used in this description are only with reference to the orientation shown in the figures and that in practice the whole effector can be arranged in any spatial orientation as it is attached to an industrial robot.
[0030] FIGS. 5a and b show a frontal detail view of jaws 20 and 21. One can see how the jaws are arranged with respect to the tooth wheel 42, and that the jaws will rotate together with the tooth wheel 42 and the holder 40. The jaw 20 comprises a particular gripping surface, namely a concave respectively V-shaped gripping surface 22 to provide a self-centering feature. The gripping surface of jaw 21 in turn is straight, i.e. jaw 21 has a straight gripping surface 24. However, alternatively, also jaw 21 could be provided with a similar concave gripping surface. The skilled person will recognize that when a rivet is inserted between the two jaws, and the jaws are closed, the V-shaped gripping surface 22 will automatically center the rivet. Further, due to the symmetrical arrangement of the levers that move the jaws, both jaws 20 and 21 will always close simultaneously and to the same extent, so that any rivet will not only be centered in a horizontal direction, but also in a vertical direction, i.e. any cylindrical mechanical fastener when gripped with the inventive gripping device will automatically and advantageously exactly align in center 25 of jaws 20 and 21.
[0031] In FIG. 6, for illustrative purposes, an industrial robot 200 is shown, that is equipped with the effector 100 (the effector 100 is only sketched). The skilled person will realize that the effector 100 can be part of a larger effector that may comprise additional installation means, such as drilling devices, measurement facilities, rivet installation tools etc.
[0032] While the present invention has been illustrated by a description of various embodiments, and while these embodiments have been described in considerable detail, it is not intended to restrict or in any way limit the scope of the appended claims to such detail. The various features shown and described herein may be used alone or in any combination. Additional advantages and modifications will readily appear to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details, representative apparatus and method, and illustrative example shown and described. Accordingly, departures may be made from such details without departing from the spirit and scope of the general inventive concept.
REFERENCE SIGNS
[0033] 1 Gripping device [0034] 10 Housing [0035] 20, 21 Jaws [0036] 22 V-shaped gripping surface [0037] 23 Stop member [0038] 24 Straight gripping surface [0039] 25 Center [0040] 30, 31 Lever arm [0041] 32, 33 Free end of lever arm [0042] 34, 35 Pivot axis of lever arm [0043] 36, 37 Actuating projection of lever arm [0044] 38, 39 Pivot pin of lever arm [0045] 40 Holder [0046] 41 Return springs [0047] 42 Tooth wheel [0048] 45, 46 Drive wheels [0049] 50 Actuating piston [0050] 51 Piston pin [0051] 53 Bearing [0052] 60 Cover [0053] 61 Sealing ring [0054] 62 Pneumatic connector [0055] 80, 81, 82 Rivets [0056] 100 Robot effector [0057] 101 Frame [0058] 102, 103, 104 Feed lines [0059] 105 Fixing plate of frame [0060] 106 Controllers [0061] 110 Feeder mechanism [0062] 111, 112, 113 Outlets of feeder mechanism [0063] 120 Axis of rotation of gripping device [0064] 121 Slide for linear movement of gripping device [0065] 130 Supply station for additives [0066] 131 Supply line for additives [0067] 200 Industrial robot
