Shock protection device for robots

Description

[0001] The invention relates to a shock protection safety device for robots designed according to the preamble of claim 1.

[0002] A generic impact protection safety device is known, for example, from DE 36 05 505 A1. The known safety device comprises a buffer or damping mechanism to be arranged between a swivel arm and a working arm of a robot. If an impact force acts on the working arm during operation of the robot, this force is to be absorbed by the buffer mechanism, whereby a sensor switch, which is part of the safety device, gives a signal to immediately stop the operation of the robot.

[0003] A plate of the impact protection safety device according to DE 36 05 505 A1, connected to the robot's swivel arm, is referred to as a "stationary plate." In contrast to the stationary plate, a movable plate, attached to the robot's working arm and also part of the impact protection safety device, has limited movement. A conical guide element is screwed to the movable plate and engages in a guide hole located in the stationary plate. The stationary plate also contains several through-holes, each with a sliding pin. Each of these pins is attached to a piston located on the side of the stationary plate facing away from the movable plate. Each piston simultaneously contacts a recess in the surface of the movable plate.When the movable plate is moved towards the stationary plate, the pins, which are not rigidly attached to the movable plate and thus allow relative rotation between the two plates, push the piston away from the stationary plate. Compression springs counteract this movement of the piston, directly loading it. Additionally, the piston can be subjected to compressed air in the direction of the springs' action.

[0004] German patent application DE 10 2015 224 641 A1 discloses a method for detecting a collision between a robot arm and an object. This method utilizes several position sensors of the robot, an electronic control device, and multiple drives.

[0005] A collision protection device for a robot described in DE 10 2017 217 882 A1 comprises, in principle comparable to the device described in DE 36 05 505 A1, a first main body designed for attachment to a drive part of the robot and a second main body designed for coupling to an end effector of the robot. The second main body is pre-tensioned to a home position relative to the first main body by means of pre-tensioning means.

[0006] An anti-collision protection device for a robot, described in DE 21 2020 000 034 U1, comprises a mounting plate on which sliding rails are located. Connecting rods are guided on the sliding rails and coupled to a hollow spring plate. A plurality of shock-absorbing springs are located in the hollow spring plate.

[0007] Another impact protection device for robots is described in CN 211 491 630 U. This device also comprises several components with limited movement relative to each other, which are pre-tensioned by springs.

[0008] US Patent 2020 / 254628 A1 describes a screwdriving device comprising a screwdriver and a connecting element for coupling the screwdriver to a robot arm. The connecting element has a first robot-side transmission element, a second tool-side transmission element, a return element located between the first and second transmission elements, and a distance measuring element. The two transmission elements can be moved toward each other in an actuation direction against a restoring force of the return element. The distance measuring element measures a distance that represents the distance between the transmission elements in the actuation direction and is used to control the actuation force acting on the screwdriver.

[0009] US Patent 2004 / 128850A1 discloses a remotely controlled central compliance device comprising an upper and a lower structure arranged parallel to each other, a plurality of elastic bodies coupling the upper and lower structures around a central axis of the remote central compliance; and three or more polar-type limiters of equal height installed on a first structure of one of the upper and lower structures around the central axis to extend towards a second structure of the other.The limiters are arranged such that at least one limiter exists on each of the two sides with respect to a straight line passing through the central axis on a plane perpendicular to the central axis, so that if a predetermined elastic displacement of an upward and downward direction occurs in the elastic bodies, the predetermined elastic displacement of the elastic bodies is limited by supporting a contact surface installed on an end section of the respective limiters by a base plate installed on the second structure.

[0010] CN 101 863 035 B describes a flexible waist for a robot, consisting of a moving part, an oscillating part, a displacement sensor, and an angle sensor. The moving part implements the motion function in one direction, the oscillating part implements the oscillation function in two directions, and springs are arranged in both the moving and oscillating parts. The flexibility and restoring function of the waist in the direction of movement and oscillation are achieved through the elasticity of the springs. The contact state of operating objects can be identified by the information from a position sensor and an angle sensor arranged at the waist.

[0011] The invention is based on the objective of providing a further developed impact protection safety device for robots compared to the aforementioned prior art, which is characterized by a particularly manufacturable, compact and at the same time robust design.

[0012] This problem is solved according to the invention by a shock protection safety device suitable for use with a robot, comprising the features of claim 1. The shock protection safety device comprises a first connecting part, which is provided for connection with a robot arm, and a second connecting part provided for connection with an actuator, wherein the two connecting parts interact with each other by means of guides of the first and second type and several spring elements designed as compression springs are stretched between the connecting parts.

[0013] The various guide types each comprise several pins connected to the second connecting part, which allow movement of the second connecting part only along parallel central axes of the pins relative to the first connecting part. The pins belonging to the first type of guide each have a stop contour that engages behind the first connecting part in the extension direction—that is, a contour of the first connecting part that prevents the second connecting part from being completely removed from the first. In contrast to the pins that constitute components of the first type of guide, the pins belonging to the second type of guide are each surrounded by one of the aforementioned spring elements.

[0014] The shock protection safety device comprises a position sensor designed to detect the relative positioning of the connecting parts, which is integrated into an actuator-sensor box. In addition to the position sensor, the actuator-sensor box includes electrical and / or fluidic components, i.e., pneumatic or hydraulic components. The actuator-sensor box is attached to or integrated into the first connecting part. The position sensor detects whether the second connecting part, after undergoing a compensating movement due to an overload (i.e., being moved against spring force towards the first connecting part), has returned to its initial position.

[0015] There is thus a clear separation of functions performed by the different guides, whereby at least one of the two guides, in particular exactly one of the two guides, namely the first type of guide, can be designed as a linear sliding bearing with guide shafts as journals. An additional function is provided by the first guide as a stop, and by the second guide as a spring that repels the connecting parts from one another. The second guide is not necessarily designed as a linear bearing. For example, the function of the journals of the second guide may be solely to support the spring elements.Thanks to the precise, rotationally fixed linear bearing, which is achieved with the help of the guide shafts, only a small spring force of the spring elements is sufficient for the desired functionality of the impact protection safety device, whereby after its response, i.e. after a collision-induced compression of the spring elements, a return to the initial position, i.e. to the maximum relaxed state of the spring elements, takes place solely by spring force, depending on the orientation of the safety device additionally by weight force.

[0016] In an advantageous, particularly slim design of the impact protection safety device, which is especially suitable for industrial robots, the central axes of all pins lie in a common plane, which is equivalent to the fact that the pins are arranged in a single straight row, with the pins belonging to the first type of guide being arranged between those pins belonging to the second type of guide.

[0017] In this case, for example, the guide of the first type, as well as the guide of the second type, has exactly two pins, with a fastening contour on the first connecting part, which is intended for connection to a counter contour of a robot arm, being arranged between the two pins, which are attributable to the guide of the first type.

[0018] To attach the first connection part, also known as the base body of the impact protection safety device, to a robot arm, the mounting contour on the first connection part can include a mounting flange that is positioned closer to the second connection part than the contour of the first connection part that interacts with the stop contour of the pins. This particularly small distance between the mounting contour and the second, movable connection part ensures excellent stability of the entire safety device, especially in the case of tilting loads acting on the second connection part via an actuator attached to it.

[0019] The side of the first connection part on which the mounting flange is located is defined, without loss of generality, as the top. Compared to the first connection part, the second connection part typically has a less complex, flatter, cuboid-like shape, with one upper edge of this cuboid aligned parallel to a lower edge of the first connection part. The so-called top edge of the second connection part is defined, irrespective of the actual orientation of the impact protection safety device in space, as the edge of the second connection part that is furthest from the first connection part, apart from the pins. The second connection part is also referred to as the actuator flange or connecting part of the impact protection safety device.

[0020] According to one possible embodiment, the pins belonging to the second type of guide are shorter than the spring elements and shorter than the pins belonging to the first type of guide. In the position where the second connecting part is raised to its maximum extent, they are completely separated from the first connecting part, meaning they are pulled out of it. This has the advantage that, in the basic position of the impact protection safety device—that is, when the second connecting part is raised to its maximum extent—the fully extended state of the pins of the second type of guide is easily visually recognizable. The pins belonging to the second type of guide only assume their function as components of a linear guide between the two connecting parts once the second connecting part has already been partially displaced towards the first connecting part against the force of the spring elements.Only with a further displacement of the second connecting part, and thus increasing spring forces, can the pins of the second type of guide act as linear guide components in addition to the pins belonging to the first type of guide. Designs in which the pins belonging to the second type of guide serve exclusively to support the springs and optionally also have a stop function when the connecting parts are pushed together are also possible.

[0021] If the second connecting part is shifted maximally towards the first connecting part, a stop may occur because the main components of the two connecting parts, referred to as connection blocks, abut each other. However, if the displacement of the second connecting part is limited by the fact that the pins belonging to the second type of guide are stopped in a defined manner in blind holes located in the first connecting part, which represent contours of the second type of guide, then even when the connecting parts are maximally compressed, a gap remains between the lower edge of the first connecting part and the upper edge of the second connecting part.

[0022] Optionally, the impact protection safety device includes a hood that covers the first connection point and can be attached to it. This hood may have a closed surface on the side facing away from the second connection point. The closed design of the surface ensures that no space needs to be kept clear for the robot arm at that location and is particularly effective as dust protection. The hood, i.e., the housing cover, can be attached to the first connection point without tools, for example, by a snap-fit ​​connection, i.e., by clipping it on.

[0023] In a particularly manufacturing-friendly manner, especially for small production runs, it is possible to produce either the first or second connection part, or both connection parts and / or the cover as 3D-printed parts, i.e., additively manufactured. In principle, metallic materials as well as non-metallic materials are suitable for 3D printing the connection parts, and they can also be additively manufactured from a combination of metallic and non-metallic materials. For example, if at least one connection part is made of plastic, it is 3D printed using a continuous fiber-reinforced core. Carbon fibers are particularly suitable for reinforcing the connection part.When both connecting parts are made of plastic, it has proven advantageous for the pins attributable to the guide of the first type to each be guided in at least one recirculating ball bushing. It has also proven advantageous for at least one of the connecting parts to be made of aluminum and for the pins attributable to the guide of the first type to each be guided in at least one recirculating ball bushing. It is particularly preferred if both connecting parts are made of aluminum.

[0024] The provision of ball bearing bushings enables particularly precise guidance of the journals belonging to the first type of guide and reliably prevents tilting of the first connecting part relative to the second connecting part.

[0025] To detect the relative positioning of the two connection parts, a position sensor is provided, which is integrated into or interacts with an actuator-sensor box. This box, which includes electrical and / or fluid-technical components (i.e., pneumatic or hydraulic) in addition to the position sensor, is attached to or integrated into the first connection part. The position sensor detects whether the second connection part, after undergoing a compensating movement due to an overload (i.e., being moved against spring force towards the first connection part), has returned to its initial position. In a typical design, this return to the initial position occurs without pneumatic assistance.

[0026] Regardless of the design or presence of an actuator-sensor box, pneumatic or hydraulic connections can be located on both connection parts. In particular, the first connection part can have clamping brackets for lines, i.e., electrical lines and / or fluid hoses. These clamping brackets can be formed, particularly advantageously in manufacturing, especially in the case of additive manufacturing of the first connection part, integrally with the components of the guides of any type formed by the first connection part, including the contour that interacts with the stop contours of the pins.

[0027] An embodiment of the invention is explained in more detail below with reference to a drawing. The drawing shows: Fig. 1 a shock protection safety device in simplified cutaway view, Fig. 2 the safety device in side view, Fig. 3 the safety device including a hood in perspective view.

[0028] A shock protection safety device, designated with reference numeral 1, is intended for use with an industrial robot. Regarding the fundamental function of safety device 1, reference is made to the prior art cited at the beginning.

[0029] The impact protection safety device 1 is composed of two connection parts 2, 3: a first connection part 2, also referred to as the base body, which is to be connected to an arm of the robot, and a second connection part 3, which is to be connected to an end effector of the robot. In the exemplary embodiment, the end effector is in the form of an actuator 4, which is permanently connected to the second connection part 3.

[0030] In normal robot operation, a fixed geometric relationship exists between the connection parts 2 and 3. A safety function of the device 1 is that, when high impact forces act upon it, the second connection part 3 can be displaced against spring force in the direction of the first connection part 2. The corresponding displacement direction is designated VR. Since the displacement direction VR is defined as the z-direction, the entire impact protection safety device 1 is also referred to as the z-compensation module. Movement of the second connection part 3 relative to the first connection part 2 is only possible in the displacement direction VR and in the opposite direction, reliably preventing the second connection part 3 from tilting relative to the first connection part 2. A mounting flange 5 of the first connection part 2 lies in a plane that—based on a Cartesian coordinate system—is parallel to the corresponding xy-plane.The mounting flange 5 is part of a fastening contour of the first connection part 2, designated 6. Fastening screws for attaching the first connection part 2 to the robot arm are designated 7.

[0031] The linear, mechanically preloaded movement of the second connection part 3 relative to the first connection part 2 is achieved by a guide 8 of the first type and a guide 9 of the second type. The guide 8 of the first type is effective over the entire displacement path of the second connection part 3. The guide device, designated 10, which comprises the different guides 8 and 9, also includes spring elements 11, which are compression springs in the form of helical springs. The spring elements 11 preload the two connection parts 2 and 3 relative to each other such that a maximum distance Dmax can be established between them. The maximum distance Dmax is measured between the lower edge (UK) of a connection block 12 of the first connection part 2 and the upper edge (OK) of a connection block 13 of the second connection part 3.The displacement path by which the second connection part 3 can be displaced relative to the first connection part 2 corresponds to the maximum distance D max .

[0032] Both connection blocks 12, 13, which represent the main components of the connection parts 2, 3, are 3D printed parts made of aluminum.

[0033] The second connection part 3 comprises, in addition to the connection block 13, two pins 14 and 15, which are assigned to the guide 8 of the first type and the guide 9 of the second type, respectively. Screws with which the pins 14 are fastened to the connection block 13 are designated 16, and the double-flat contours of the pins 14 are designated 17.

[0034] The two pins 14, also referred to as guide shafts, engage in the first connecting part 2 in every state of the safety device 1 and ensure that the two connecting parts 2, 3 can never be rotated relative to each other. Stop contours 18 at the end of each pin 14 prevent the pins 14 from being pulled out of the connecting block 12. The stop contours 18 are undercuts that engage behind contours 19 of the first connecting part 2. (Referring to the arrangement according to...) Fig. 1 The pins 14 can therefore only be inserted into the connecting block 12 from above. The diameter of each pin 14 is designated d 14. Preferably, the first connecting part 2 in the area of ​​the guide for the pins 14 comprises at least one ball bearing (not shown here), which increases the precision of the guide for the pins 14.

[0035] The two pins 14 are arranged between the pins 15, which are part of the second-type guide 9 and each have a diameter d 15. The central axes of all pins 14, 15 lie in a common plane parallel to the yz-plane. The free length LF, by which the pins 15 project from the terminal block 13, is, in the exemplary embodiment, less than the maximum distance D max between the upper edge OK of the terminal block 13 and the lower edge UK of the terminal block 12.

[0036] Each pin 15 is surrounded by one of the spring elements 11, which simultaneously engages in a pocket 20 formed by the connecting block 12 and abuts the bottom 21 of the pocket. In the fully extended state of the second connecting part 3, as shown in the figures, the pins 15 hold the spring elements 11 in position. The depth of the pockets 20 is slightly greater than the free length LF of the pins 15, so that they cannot abut the bottom 21 of the pocket. Rather, when the connecting part 3 is fully inserted, the upper edge OK of the connecting block 13 rests against the lower edge UK of the connecting block 12.

[0037] The distance measured in the z-direction, i.e., the feed direction VR, between the lower edge (UK) of the connection block 12 and the upper surface of the mounting flange 5 is designated D5 and is less than the distance designated D19 between the contour 19 on the connection block 12, which enables the stop of the pins 14 – more precisely, the stop contours 19 – and the lower edge (UK). The designations "OK" and "UK" refer to the orientation of the safety device 1 shown in the figures, in which the z-direction corresponds to the vertical direction. By arranging the contours 19 above the mounting flange 5, a long guide path for the pins 14 within the connection block 12 is provided, while the distance D5 between the mounting flange 5 and the lower edge (UK) is minimized in order to keep any tilting moments acting on the connection part 2 to a minimum.

[0038] A sensor 22 is provided to detect the relative positioning of the connection parts 2 and 3. This sensor is attached to the terminal block 12 and interacts with an actuator-sensor box 23, which is also part of the first connection part 2. An electrical line connected to the sensor 22, i.e., the position sensor, is designated 24. The impact protection safety device 1, including the sensor 22, is designed such that it can activate during operation by pressing the connection part 3 against the connection part 2 without utilizing its full displacement range. This results in partial compression of the spring elements 11 without impairing the function of the actuator 4 or stopping the robot. Under no operating conditions is the second connection part 3 rotated or tilted relative to the first connection part 2.

[0039] Pneumatic connections 25 are also visible on both connection parts 2. Furthermore, the first connection part 2 has clamping brackets 26, which are directly formed by the plastic connection block 12. The clamping brackets 26 can be used to hold pneumatic hoses or cables (not shown).

[0040] The impact protection safety device 1 is completed by a multi-part cover 27, which is placed on the first connecting part 2. A closed top surface of the cover 27 is designated 28. In the exemplary embodiment, the side surfaces 29 of the cover 27 have slots 30. The cover 27 can be placed on and removed from the first connecting part 2 without tools. The cover 27 is preferably made of plastic and manufactured using a 3D printing process. Reference symbol list

[0041] 1 Shock protection safety device 2 First connection part 3 Second connection part 4 Actuator 5 Mounting flange 6 Mounting contour 7 Screw 8 First-type guide 9 Second-type guide 10 Guide device 11 Spring element 12 First connection block 13 Second connection block 14 Pin 15 Pin 16 Screw 17 Double-flat contour 18 Pin stop contour 14 19 Contour on first connection part, interacting with stop contour 18 20 Pocket 21 Pocket bottom 22 Position sensor 23 Actuator sensor box 24 Electrical cable 25 Pneumatic connection 26 Clamp bracket 27 Cover 28 Top surface 29 Side surface 30 Slot D max Maximum distance D 5 Distance of the mounting flange 5 from the lower edge d 14 Diameter of a pin 14 d 15 Diameter of a pin 15 D 19 Distance of the contour 19 from the lower edge LF Free length OK Top edge UK Bottom edge VR Direction of movement

Claims

1. An impact protection safety device for robots, - having a first connection part (2), which is provided for connection to a robot arm, and - a second connection part (3), which is provided for connection to an actuator (4), wherein - the connection parts (2, 3) interact with one another by means of guides (8, 9) of a first type and a second type and multiple spring elements (11) designed as compression springs are spanned between the connection parts (2, 3), wherein the various guides (8, 9) each comprising multiple pins (14, 15) which are connected to the second connection part (3) and which allow movement of the second connection part (3) only along parallel-oriented central axes of the pins (14, 15) relative to the first connection part (2), wherein - the pins (14) belonging to the guide (8) of the first type each having a stop contour (18) which engages behind a contour (19) of the first connection part (2), which contour is effective in a direction of extension that is directed away from the first connection part (2), and - the pins (15) belonging to the guide (9) of the second type are each surrounded by one of the spring elements (11), and having - a position sensor (22) which is provided for detecting the relative position of the connection parts (2, 3) and which is integrated into an actuator-sensor box (23) or interacts with an actuator-sensor box (23) which, in addition to the position sensor system, comprises electrical and / or flow, i.e. pneumatic or hydraulic, components, the actuator-sensor box (23) being attached to or installed in the first connection part (2), and the position sensor (22) being used to detect whether the second connection part (3), after it has undergone a compensating movement due to an overload, i.e. has been displaced against spring force in the direction of the first connection part (2), has returned to its initial position.

2. The safety device according to claim 1, wherein the central axes of all the pins (14, 15) lie in a common plane, wherein the pins (14) belonging to the guide (8) of the first type are arranged between those pins (15) belonging to the guide (9) of the second type.

3. The safety device according to claim 2, wherein the guide (8) of the first type as well as the guide (9) of the second type has exactly two pins (14, 15), wherein a fastening contour (6) on the first connection part (2), which fastening contour is provided for connection to a counter contour of a robot arm, is arranged between the two pins (14) belonging to the guide (8) of the first type.

4. The safety device according to claim 3, wherein the fastening contour (6) present on the first connection part (2) comprises a mounting flange (5) which is spaced less far from the second connection part (3) than the contour (19) of the first connection part (2) which interacts with the stop contour (18) of the pins (14).

5. The safety device according to any one of claims 1 to 4, wherein the pins (15) belonging to the guide (9) of the second type are shorter than the spring elements (11) and shorter than the pins (14) belonging to the guide (8) of the first type and are completely spaced apart from the first connection part (2) in the position of the second connection part (3) maximally raised from the first connection part (2).

6. The safety device according to any one of claims 1 to 5, wherein a cover (27) covering the first connection part (2) and held on it has a closed cover surface (28) on its face facing away from the second connection part (3).

7. The safety device according to any one of claims 1 to 6, wherein at least one of the connection parts (2, 3) and / or the cover (27) is / are designed as a 3D printed part.

8. The safety device according to claim 7, wherein the connection part (2, 3) designed as a 3D printed part and / or the cover (27) is / are made of plastic having a continuous fibre-reinforced core.

9. The safety device according to any one of claims 1 to 8, wherein at least one of the connection parts (2, 3) is made of aluminium and the pins (14) belonging to the guide (8) of the first type are each guided in at least one linear ball bearing.

10. The safety device according to claim 9, wherein the two connection parts (2, 3) are made of aluminium.

11. The safety device according to any one of claims 1 to 10, characterized by pneumatic connections (25) on the two connection parts (2, 3) and multiple clamping holders (26) for pneumatic hoses on the first connection part (2), wherein the clamping holders (26) are formed integrally with the components, formed by the first connection part (2), of the guides (8, 9) of either type, including the contour (19) which interacts with the stop contours (18) of the pins (14).