Robot arm and robot equipped with robot arm

Abstract

The present invention relates to a robot arm (1) for a robot (10), the robot arm comprising a robot hand shaft (2) having a plurality of arm segments (3, 4), the first arm segment (3) and the second arm segment (4) of the robot hand shaft (2) being attached to each other by at least one angular contact needle bearing (5), the first arm segment (3) and the second arm segment (4) comprising a rotatably mounted first bearing ring (6) and a second bearing ring (7) mounted so as to be rotatable relative to the first bearing ring (6). a rotatably mounted first bearing ring (6) supported on the first arm segment (3), and a rotatably mounted second bearing ring (7) supported on the second arm segment (4) and operatively connected to at least one first cable (12a), the at least one first cable (12a) configured to adjust the rotational position of the second bearing ring (7) relative to the first bearing ring (6) in at least a first direction of rotation by actuation by the motor unit (8). The present invention also relates to a robot (10) comprising such a robot arm (1).

Description

[Technical Field]

[0001] The present invention relates to a robot arm for a robot, comprising a robot hand axis with a plurality of arm segments, a first arm segment and a second arm segment of the robot hand axis attached to each other by at least one bearing element, the first arm segment having a first bearing ring arranged non-rotatably and a second bearing ring arranged rotatably relative to the first bearing ring, the first non-rotatable bearing ring being supported on the first arm segment and the second rotatable bearing ring being supported on the second arm segment. The present invention also relates to a robot having such a robot arm. [Background technology]

[0002] Known fixed industrial robots have six axes, i.e., six degrees of freedom. Such six-axis robots are particularly suitable for loading and unloading injection molding machines, assembling, coating, polishing, laser cutting, and plasma cutting processes. Six-axis robots are particularly characterized by a lightweight construction, a high level of precision, a high movement speed, a compact mechanical structure, and a small footprint.

[0003] For example, German Patent Application Publication No. 102016003966 discloses a coating robot for coating components, particularly automotive body components. The robot includes a robot base, a rotating robot member mounted on the robot base and rotatable about a first axis relative to the robot base, and a proximal robot arm mounted on the rotating robot member and pivotable about a second axis relative to the rotating robot member. The proximal robot arm has two arm portions rotatable relative to each other about a third axis substantially aligned along the longitudinal axis of the proximal robot arm via a first bearing ring. The robot further includes a distal robot arm mounted on the proximal robot arm and pivotable about a fourth axis relative to the proximal robot arm, and a robot hand shaft mounted on the distal robot arm and having multiple, particularly three, movable axes. A connection flange is provided at the free end of the robot hand shaft for connecting an application device. The three axes are typically the fourth, fifth, and sixth axes of the robot arm, which allow the application device to be precisely pivoted and positioned in a small space. The arm sections are controlled by gear elements, particularly a gear train, located inside the robot arm. Summary of the Invention [Problem to be solved by the invention]

[0004] The object of the present invention is to provide a robotic arm and a robot that have a lower overall weight, are easier to assemble and are less prone to errors. This object is achieved by the subject matter of claims 1 and 10. Preferred embodiments can be found in the dependent claims, the description and the drawings. [Means for solving the problem]

[0005] A robot arm according to the present invention for a robot comprises a robot hand axis with a plurality of arm segments, a first arm segment and a second arm segment of the robot hand axis being attached to one another by at least one angular contact needle bearing, and having a first bearing ring arranged non-rotatably and a second bearing ring arranged rotatably relative to the first bearing ring, the first non-rotatable bearing ring being supported on the first arm segment and the second rotatable bearing ring being supported on the second arm segment and operably connected to at least one first cable, the at least one first cable being configured to adjust the rotational position of the second bearing ring relative to the first bearing ring in at least one first direction of rotation by actuation by a motor unit.

[0006] The robot arm is configured to be at least indirectly mounted on a robot base, particularly a fixed robot base. The robot hand axis is a composite hand axis that combines the fourth, fifth, and sixth axes of the robot into a single component or structural unit. Therefore, the robot hand axis is located at one end of the robot arm, and only application devices specific to the robot application are attached to the robot hand axis. Each of the three axes is formed by two arm segments attached to each other, where one arm segment can rotate relative to the other arm segment around its respective axis, but the other arm segment is arranged so that it cannot rotate relative to the other arm segment.

[0007] By actuating the motor unit, the rotatably arranged second bearing ring begins to rotate via at least a first cable to adjust the precise rotational position of the second bearing ring relative to the first bearing ring in each direction of rotation. To this end, the second bearing ring is actuated via at least a first cable. The at least a first cable may be configured such that the second bearing ring is equally rotatable in both directions of rotation. Alternatively, the at least a first cable may be configured such that the second bearing ring is rotatable only in the first direction of rotation. In this case, the robot hand axis has a second cable that can rotate the second bearing ring in a second direction of rotation opposite to the first direction of rotation. By adjusting the rotational positions of the bearing rings relative to each other, the rotational positions of the arm segments relative to each other are adjusted. Thus, the rotational position of the first arm segment relative to the second arm segment can be adjusted via at least a first cable by actuating the motor unit. The at least a first cable has sufficient flexibility to allow deflection.

[0008] In the present invention, the bearing rings of an angular contact needle bearing refer to both the inner and outer rings of the angular contact needle bearing. Depending on the arrangement and configuration of the angular contact needle bearing, the outer ring may be non-rotatably arranged and the inner ring may be rotatable relative to the outer ring, or the inner ring may be non-rotatably arranged and the outer ring may be rotatable relative to the inner ring. A plurality of needle-shaped rolling elements are spatially arranged between the bearing rings, preferably guided in a cage. At least one angular contact needle bearing may also have two or more non-rotatably arranged bearing rings and / or two or more bearing rings rotatably arranged relative to the bearing rings. In addition, the angular contact needle bearing may be configured with one or more rows. Preferably, at least one angular contact needle bearing is a double-row angular contact needle bearing. This allows the angular contact needle bearing to have two rows of needle-shaped rolling elements, which axially position and fix the two arm segments relative to each other.

[0009] The at least first cable is configured to transmit force from the motor unit to the second bearing ring via cable transmission to adjust the rotational position of the second bearing ring. The at least first cable has a pivot point, which should be understood as a force application point on the motor side for introducing tension into the traction cable of the at least first cable, and the introduced force is transmitted via the cable to the second bearing ring at the deflection point. The traction cable of the at least first cable is simply referred to as a rope. This rope may preferably be a wire rope that is stable in tension. Compared to gears, particularly gear trains, cables are lightweight, flexible to use, and easy to assemble. Therefore, the rope of the cable should be understood as a traction means in the form of, for example, a wire rope, operably connected to both the rotatably arranged bearing ring and, at least indirectly, to the motor unit.

[0010] Preferably, the rope of at least the first cable is wound at least 1.5 times around the rotatable second bearing ring of the angular contact needle bearing. Therefore, the number of turns is at least 1.5. This allows each arm segment to rotate at least 360°. The rope can also be wound more than 1.5 times around the second bearing ring. The more rope wound around the second bearing ring, i.e., the greater the number of turns, the greater the rotation angle of the second bearing ring relative to the first bearing ring or the rotation angle of the second arm segment relative to the first arm segment. The rope is preferably wound helically around the second bearing ring. It is also conceivable to wind the rope around the second arm segment or around an element formed on or fixed to the second bearing ring.

[0011] Furthermore, a spirally circumferential groove is preferably arranged on the rotatable second bearing ring of the angular contact needle bearing for at least partially receiving the rope of at least the first cable. The configuration of the groove, particularly the number of turns, is adapted to the desired angle of rotation of the second bearing ring or the second arm segment. Thus, the groove is configured as a kind of thread that serves to receive the rope.

[0012] According to a first exemplary embodiment, the rope of at least the first cable is guided through an angular contact needle bearing, in particular through the end face of a non-rotatable first bearing ring, which is arranged on a rotatable second bearing ring and attached to an anchoring point, as described. The second bearing ring must therefore be configured so that the rope can be wound around it, guided, and anchored in place. In an alternative embodiment, the rope of at least the first cable is guided through a corresponding opening in the non-rotatable first bearing ring. An opening is understood as a recess or hole in the first bearing ring through which the rope of at least the first cable can pass. This allows for a more compact and space-saving design of the robot hand axis.

[0013] The motor unit can be spatially arranged directly adjacent to the shaft or inside the shaft, i.e., within the angular contact needle bearing. However, for weight reasons, it may be advantageous to position the motor unit closer to the base of the robot. In this sense, at least the first cable is preferably configured and arranged relative to the angular contact needle bearing and the arm segment such that the motor unit is spatially arranged outside the at least one angular contact needle bearing.

[0014] The cable can be configured to allow the rotational position of the second bearing ring relative to the first bearing ring to be adjusted equally in a first direction of rotation and in a second direction of rotation opposite to the first direction of rotation.

[0015] In a preferred exemplary embodiment, at least the first cable is configured as a Bowden cable. A Bowden cable is a movable mechanical element that transmits mechanical movements as well as compressive and tensile forces in the direction of movement by means of a flexible combination of a wire rope and a pressure-resistant sheath, also referred to below as a Bowden cable sheath. Control of the second bearing ring by means of a Bowden cable is characterized by its relatively easy assembly, low cost and low weight.

[0016] The present invention includes a technical teaching that the rope of at least a first cable is partially received in at least one Bowden cable sheath. The flexible Bowden cable sheath is arranged between the motor unit and the angular contact needle bearing. The Bowden cable sheath may be a pressure-resistant hose in which the rope of at least the first cable is arranged. The Bowden cable also has an abutment for introducing a reaction force to the Bowden cable sheath against tensile and / or compressive forces. The abutment may be one end of the Bowden cable sheath. The Bowden cable is supported by a flexible and non-rotatable bearing ring. The first bearing ring is therefore configured to provide a stop for the Bowden cable, particularly the Bowden cable sheath, against which the Bowden cable can be supported.

[0017] Preferably, at least the first cable comprises a pulley, which is partially wound with the rope of the first cable and is configured to be rotated by a motor unit to adjust the rotational position of the rotatable second bearing ring. The rope is thus anchored on one side to the pulley and on the other side to the second bearing ring, so that rotation of the pulley results in immediate rotation of the rotationally driven second bearing ring. Furthermore, the rope is preferably wound around the pulley by at least 1.5 turns around the second bearing ring or pulley. For this purpose, the pulley, like the second bearing ring, can have a helically formed groove on its outer periphery. The rope is guided from the pulley to the second bearing ring via a first Bowden cable sheath and, after at least 1.5 turns, is guided back from the second bearing ring to the pulley via a second Bowden cable sheath.

[0018] According to an exemplary embodiment, the robot hand axis preferably includes a plurality of angular contact needle bearings, each of which includes at least one non-rotatably arranged first bearing ring and at least one second bearing ring rotatably arranged relative to the first bearing ring, as described above. At least one of the angular contact needle bearings, or its rotatable second bearing ring, is operably connected to at least a first cable. It is contemplated that the plurality of angular contact needle bearings may be operably connected to at least one separate cable as described above. Preferably, each angular contact needle bearing is operably connected to at least one separate cable. Thus, the robot hand axis preferably includes at least three cables: at least one first cable for a fourth axis for controlling a corresponding arm segment, at least one second cable for a fifth axis for controlling a corresponding arm segment, and at least one third cable for a sixth axis for controlling a corresponding arm segment.

[0019] Preferably, the rotatable second bearing ring is operably connected to two cables, the first cable being configured to adjust the rotational position of the second bearing ring relative to the first bearing ring in a first direction of rotation by actuation by the motor unit, and the second cable being configured to adjust the rotational position of the second bearing ring relative to the first bearing ring in a second direction of rotation opposite to the first direction of rotation by actuation by the motor unit. In other words, the cables act on each other, i.e., in opposite directions, so that the rotational position of the second bearing ring relative to the first bearing ring can be precisely adjusted. This is particularly advantageous for cables configured as Bowden cables, since these cables are more suitable for transmitting tensile forces and only to a limited extent for transmitting compressive forces. With respect to the second cable, everything stated above for at least the first cable applies analogously. It is also conceivable to use two or more cables for one axis, in particular for the fourth, fifth, and sixth axes of the robot arm.

[0020] The present invention further relates to a robot comprising a robot arm according to any one of the preceding claims, the robot arm being arranged on a robot base. The robot base is mounted in a fixed position by suitable means, for example on a housing, in a cabin, or on a frame. The robot arm can be pivotally arranged on the robot base. Alternatively, the robot base can be mounted on a mobile carriage or form the carriage itself, giving the robot seven degrees of freedom. The robot arm is arranged on the robot base and has multiple arm segments connected to each other at joints in a known manner. The robot hand axis is arranged at the end of the robot arm opposite the robot base and preferably has means for receiving at least one application device. Lines and means for receiving the lines can be arranged inside the robot arm. The lines can be electrical lines, for example, fluid lines, depending on the field of application. The robot according to the present invention is particularly suitable as an industrial robot, in which the robot arm is a six-axis robot arm.

[0021] Further ways of improving the invention are described below with reference to the drawings and in conjunction with the description of two exemplary embodiments of the invention. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a schematic view of a robot according to the invention, only partially shown in the form of an arm robot; [Figure 2] 2 is a highly simplified diagram of a partially illustrated robot hand axis of a robot arm according to the invention of the robot according to the invention of FIG. 1; FIG. [Figure 3] FIG. 10 is a schematic cross-sectional view of an angular contact needle bearing for a robot hand axis according to an alternative embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0023] 1 shows a diagram of a robot 10 according to the invention. The robot 10 is configured as an arm robot and has a robot arm 1 configured as a six-axis robot arm according to the invention, the arm segments of which are connected to one another in a manner known per se but not described in detail here to form the robot arm 1. The robot arm 1 is mounted on a robot base 11. A robot hand axis 2 is arranged at the opposite end of the robot arm 1 and combines the fourth, fifth and sixth axes of the robot 10 in a single unit, which are not shown in detail here.

[0024] The robot hand axis 2 couples multiple axes of the robot 10 and therefore has multiple arm segments, of which a first arm segment 3 and a second arm segment 4 are only partially shown in FIG. 2 by way of example. As mentioned, the two arm segments 3, 4 can be arranged on one of the fourth, fifth or sixth axes of the robot hand axis 2, i.e., form corresponding axes. It is also conceivable that multiple or all axes of the robot hand axis 2 have the arrangements described below.

[0025] The double-row angular contact needle bearing 5 is spatially arranged between the two arm segments 3, 4 and is configured similarly to the embodiment shown in Figure 3. The angular contact needle bearing 5 has a first bearing ring 6 arranged non-rotatably and a second bearing ring 7 arranged rotatably relative to the first bearing ring 6, and a needle-shaped rolling element 9 is arranged between the bearing rings 6, 7. The angular contact needle bearing 5 supports the two arm segments 3, 4 relative to each other.

[0026] The first bearing ring 6, here configured as an outer ring, is supported on the first arm segment 3 such that the first arm segment 3 is non-rotatable relative to the second arm segment 4. The second bearing ring 7, here configured as an inner ring, is supported on the second arm segment 4 such that the second arm segment 4 is rotatably arranged relative to the first arm segment 3. Thus, the first arm segment 3 and the first bearing ring 6 form the non-rotatably grounded side of the system shown here, while the second arm segment 4, together with the second bearing ring 7, form the non-rotatably grounded side of the system.

[0027] Here, the second bearing ring 7, i.e. the inner ring forming the ungrounded side of the angular contact needle bearing 5, is operatively connected to two cables 12a, 12b, each configured as a Bowden cable. The cables 12a, 12b are operatively arranged in the power flow between the motor unit 8 controlling the second arm segment 4 and the angular contact needle bearing 5, with a pulley 17 arranged on the motor side operatively connected to the ropes 15 of the cables 12a, 12b. The pulley 17 is partially wrapped by the rope 15 of the first cable 12a and partially wrapped by the rope 15 of the second cable 12b and is configured to be initiated into rotational movement by the motor unit 8 in order to adjust the rotational position of the rotatable second bearing ring 7.

[0028] The rope 15 of the first cable 12a and the rope 15 of the second cable 12b are wound around both the pulley 17 and the second bearing ring 7, with at least 1.5 turns on each side. Each rope 15 is further anchored to a first anchorage point 18 on the second bearing ring 7 and a second anchorage point 19 on the pulley 17. Additionally, the rope 15 of the first cable 12a is disposed within a flexible first Bowden cable sheath 14, and the rope 15 of the second cable 12b is disposed within a flexible second Bowden cable sheath 20. Both Bowden cable sheaths 14, 20 are supported on the first bearing ring 6 and on the outer ring of the angular contact needle bearing 5.

[0029] When the motor unit 8 configured as a servo motor, together with the pulley 17 coupled thereto, is operated, either the rope 15 of the first cable 12a or the rope 15 of the second cable 12b is subjected to a pulling force, which causes the second bearing ring 7 to start a rotational movement in a first rotational direction or in a second rotational direction opposite to the first rotational direction. The cables 12a, 12b therefore act against each other to bring the second bearing ring 7 into the desired rotational position. Guiding the cables by the Bowden cable allows the necessary freedom of movement and ensures accurate implementation of the predetermined rotation of the second bearing ring 7 relative to the first bearing ring 6 or the second arm segment 4 relative to the first arm segment 3.

[0030] 3, a helically shaped groove 16 is arranged on the outer periphery of the rotatable second bearing ring 7 of the angular contact needle bearing 5 for receiving the ropes 15 of the respective cables 12a, 12b. This ensures that the respective ropes 15 are reliably guided on the second bearing ring 7. Each cable 12a, 12b is constructed and arranged such that a motor unit 8 is arranged on the angular contact needle bearing 5, spatially outside at least one angular contact needle bearing 5, as shown in FIG. 2. This allows the motor unit 8 to be flexibly arranged on the robot 10 or robot arm 1, for example to balance the weight ratio of the robot arm 1.

[0031] In the embodiment shown in FIG. 2, the ropes 15 of each cable 12a, 12b pass through an outer ring or first bearing ring 6 and are guided to an inner ring or second bearing ring 7 located on the inside.

[0032] In the alternative embodiment according to FIG. 3, the ropes 15 of the respective cables 12a, 12b are guided through the openings 13 of the non-rotatable first bearing ring 6 of the angular contact needle bearing 5. Here, only the ropes 15 of the first cable 12a are shown guided through the openings 13 of the non-rotatable first bearing ring 6 of the angular contact needle bearing 5. This can be provided similarly for the second cable 12b. Thus, the angular contact needle bearing 5 according to FIG. 3 is configured as an alternative to the angular contact needle bearing 5 according to FIG. 2. This allows for a more compact design of the robot hand axis 2. The ropes 15 of the first cable 12a and / or the second cable 12b can also be guided through the first arm segment 3, although this is not shown in detail here.

[0033] Figure 3 also shows that the first Bowden cable sheath 14 of the first cable 12a is supported on the outer periphery of the first bearing ring 6, which is configured as an outer ring. The outer ring thus forms an abutment for the Bowden cable. This can be similarly provided for the second cable 12b. Figure 3 also shows that the first bearing ring 6, which is similar to Figure 2, is configured in two parts. Thus, the angular contact needle bearing 5 has a single inner ring and an outer ring with two adjacent ring segments. [Explanation of symbols]

[0034] 1. Robotic Arm 2 Robot Hand Axis 3 First arm segment of the robot hand axis 4 Second arm segment of robot hand axis 5 Angular contact needle bearings 6 First bearing ring or outer ring of angular contact needle bearing 7 Second bearing ring or inner ring of angular contact needle bearing 8 Motor Unit 9 Rotational Elements 10. Robot 11 Robot base 12a First Cable 12b Second Cable 13 Opening 14 First Bowden Cable Sheath 15 Rope 16 groove 17 Pulley 18 First anchor point 19 Second anchor point 20 Second Bowden Cable Sheath

Claims

1. A robot arm (1) for a robot (10) comprises a robot hand axis (2) with a plurality of arm segments (3, 4), a first arm segment (3) and a second arm segment (4) of the robot hand axis (2) being attached to each other by at least one angular contact needle bearing (5), and having a first bearing ring (6) arranged non-rotatably and a second bearing ring (7) arranged rotatably relative to the first bearing ring (6), a rotatable second bearing ring (7) supported on the first arm segment (3), and the rotatable second bearing ring (7) supported on the second arm segment (4) and operably connected to at least one first cable (12 a), the at least one first cable (12 a) configured to adjust the rotational position of the second bearing ring (7) relative to the first bearing ring (6) in at least one first direction of rotation by actuation by a motor unit (8).

2. 2. The robot arm (1) according to claim 1, characterized in that the rope (15) of the at least first cable (12a) is wound around the rotatable second bearing ring (7) of the angular contact needle bearing (5) by at least 1.5 turns.

3. 3. The robot arm (1) according to claim 2, characterized in that a helically circumferential groove (16) is arranged on the rotatable second bearing ring (7) of the angular contact needle bearing (5) for at least partially receiving the rope (15) of the at least first cable (12a).

4. 4. The robot arm (1) according to claim 1, wherein the rope (15) of the at least first cable (12a) is guided through an opening (13) in the first non-rotatable bearing ring (6).

5. 5. The robot arm (1) according to claim 4, characterized in that the at least first cable (12a) is configured and arranged on the angular contact needle bearing (5) such that the motor unit (8) is arranged spatially outside the at least one angular contact needle bearing (5).

6. 6. Robot arm (1) according to any one of claims 1 to 5, characterized in that the at least one angular contact needle bearing (5) is a double row angular contact needle bearing.

7. 7. The robot arm (1) according to any one of claims 1 to 6, characterized in that the at least first cable (12a) is configured as a Bowden cable.

8. 8. The robot arm (1) according to any one of claims 1 to 7, characterized in that the at least first cable (12a) comprises a pulley (17) which is partially wound around by the rope (15) of the at least first cable (12a) and which is configured to be initiated into rotational movement by the motor unit (8) in order to adjust the rotational position of the rotatable second bearing ring (7).

9. 9. The robot arm (1) according to any one of claims 1 to 8, characterized in that the rotatable second bearing ring (7) is operably connected to two cables (12a, 12b), the first cable (12a) being configured to adjust the rotational position of the second bearing ring (7) relative to the first bearing ring (6) in a first direction of rotation by actuation by the motor unit (8), and the second cable (12b) being configured to adjust the rotational position of the second bearing ring (7) relative to the first bearing ring (6) in a second direction of rotation opposite to the first direction of rotation by actuation by the motor unit (8).

10. A robot (10) comprising a robot arm (1) according to any one of claims 1 to 9, the robot arm (1) being arranged on a robot base (11).

Images