Robot

Abstract

To provide a robot capable of reducing weight of an arm while rigidity of the arm is secured.SOLUTION: A robot includes a second arm having a frame 3. The frame 3 has: a plurality of beams; a first installation part 31 where a motor is installed; and a second installation part 32 where a ball screw nut is installed. The plurality of beams includes: a first beam 33 connected to the first installation part 31 and the second installation part 32; and a second beam 34 connected to the first installation part 31 and the second installation part 32, located above in the vertical direction of the first beam 33, and is of a shape protruding above. Of the first beam 33, a part nearer the first installation part 31 than the second installation part 32 is located below in the vertical direction of a part nearer the second installation part 32 than the first installation part 31.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a robot.

Background Art

[0002] For example, a robot is known that includes a base, a first arm rotatably connected to the base about a first rotation axis, a second arm rotatably connected to the first arm about a second rotation axis parallel to the first rotation axis, and a shaft supported by the second arm. Among these, the first arm and the second arm constitute a robot arm. In such a robot, from the viewpoints of reducing the inertial force of the robot arm and enabling higher-speed movement, and suppressing power consumption, etc., weight reduction of each part of the robot arm, particularly weight reduction of the second arm, is required.

[0003] Conventionally, as shown in Patent Document 1, a robot having a second arm supported by a main frame and a sub-frame in which a ball spline nut and a ball screw nut are connected via six columns, and having a structure without a side wall between the main frame and the sub-frame is known.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the robot described in Patent Document 1, since it has a main frame, a sub-frame, and six columns, there is a limit to the weight reduction of the second arm. Therefore, it is desired to further reduce the weight of the second arm while ensuring the rigidity of the second arm.

Means for Solving the Problems

[0006] The robot includes a base, a first arm rotatably connected to the base about a first rotation axis, a second arm having a frame and rotatably connected to the first arm about a second rotation axis parallel to the first rotation axis, a driving unit that rotationally drives the second arm about the second rotation axis with respect to the first arm, a shaft disposed at a position spaced horizontally from the second rotation axis in the second arm, and a support unit that movably supports the shaft. The frame has a plurality of beams, a first installation portion where the driving unit is installed, and a second installation portion where the support unit is installed. The plurality of beams include a first beam connected to the first installation portion and the second installation portion, and a second beam connected to the first installation portion and the second installation portion, located above the first beam in the vertical direction and protruding upward. Among the first beams, the portion closer to the first installation portion than the second installation portion is located below the portion closer to the second installation portion than the first installation portion in the vertical direction.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0008] 1. First Embodiment FIG. 1 is an overall view of a robot system 1 including a robot 2 according to the first embodiment. FIG. 2 is a perspective view showing a frame 3 of a second arm 24 of the robot 2. FIG. 3 is a side view of the frame 3 as viewed in the A direction (Y-axis direction) in FIG. 2. FIG. 4 is a plan view of the frame 3 as viewed in the B direction (Z-axis direction) in FIG. 2. FIG. 5 is a rear view of the frame 3 as viewed in the C direction (X-axis direction) in FIG. 2.

[0009] In FIG. 1, an X-axis, a Y-axis, and a Z-axis, which are three mutually orthogonal axes, are set, and the same three axes are also shown in FIGS. 2 to 5. Among the three axes, the Z-axis direction indicates the vertical direction, and the X-Y plane indicates the horizontal plane.

[0010] The vertical directions in FIGS. 1 to 3 and FIG. 5 coincide with the vertical direction. The +Z direction side, which is the upper side in FIGS. 1 to 3 and FIG. 5, is also referred to as "up", and the -Z direction side, which is the lower side, is also referred to as "down". For the robot arm 22, the first arm 23, the second arm 24, etc., the +X direction side, which is the right side in FIGS. 1 to 4, is referred to as the "base end" or "base end portion", and the -X direction side, which is the left side, is referred to as the "tip" or "tip portion".

[0011] In this specification, "vertical" means not only the case where it coincides with the vertical, but also the case where it is inclined slightly with respect to the vertical, for example, within ±10°. Also, in this specification, "parallel" means not only the case where two objects coincide with the parallel, but also the case where they are inclined slightly from the parallel, for example, within ±10°.

[0012] The robot system 1 shown in FIG. 1 includes a robot 2 and a robot control device 9 that controls the driving of the robot 2.

[0013] The robot 2 in this embodiment is a scalar robot, i.e., a horizontal articulated robot, and is used for various operations such as holding, transporting, assembling, processing, and inspecting workpieces such as electronic components (hereinafter sometimes simply referred to as "operations"). However, the use of the robot 2 is not particularly limited. Also, the robot 2 may be, for example, a 6-axis articulated robot, a dual-arm robot, etc., other than a scalar robot.

[0014] As shown in FIG. 1, the robot 2 has a base 21 and a robot arm 22 rotatably connected to the base 21. The base 21 is fixed to a floor surface 10 parallel to the horizontal plane. Inside the base 21, a robot control device 9 is installed. With this configuration, the cable connecting the robot 2 and the robot control device 9 etc. becomes shorter, so the heat generation amount of the cable decreases, reducing power consumption and consequently achieving energy savings. Note that, different from the illustrated configuration, the robot control device 9 may be installed outside the base 21.

[0015] The robot arm 22 has a first arm 23 and a second arm 24. The base end of the first arm 23 is connected to the base 21 and is rotatable about a first rotation axis J1 along the vertical direction with respect to the base 21. The base end of the second arm 24 is connected to the tip of the first arm 23 and is rotatable about a second rotation axis J2 along the vertical direction with respect to the first arm 23. The first arm 23 rotates within a range of a predetermined angle about the first rotation axis J1 in the horizontal plane, and the second arm 24 rotates within a range of a predetermined angle about the second rotation axis J2 in the horizontal plane above the first arm 23.

[0016] At the tip of the second arm 24, that is, at a position horizontally spaced from the second rotation axis J2 in the second arm 24, a work head 25 is provided. The work head 25 has a spline nut 251 and a ball screw nut 252 that are coaxially arranged with each other, and a spline shaft 253 inserted through the spline nut 251 and the ball screw nut 252. The spline nut 251 is located above the ball screw nut 252 and is fixed to the ball screw nut 252. The spline shaft 253 is rotatable about a third rotation axis J3 that is the central axis thereof and extends along the vertical direction with respect to the second arm 24, and is movable in the vertical direction along the third rotation axis J3. The first rotation axis J1, the second rotation axis J2, and the third rotation axis J3 are all parallel to the vertical direction. That is, the first rotation axis J1, the second rotation axis J2, and the third rotation axis J3 are parallel to each other.

[0017] The spline nut 251 supports the spline shaft 253 so as to be rotatable about the third rotation axis J3, and the ball screw nut 252 supports the spline shaft 253 so as to be movable in the axial direction of the third rotation axis J3. The spline nut 251 and the ball screw nut 252 correspond to a support portion that movably supports the spline shaft 253. Further, the spline shaft 253 corresponds to a shaft.

[0018] An end effector 26 is attached to the lower end of the spline shaft 253. The end effector 26 is detachable, and one suitable for the intended work is appropriately selected. Examples of the end effector 26 include a driver for performing screwing work, a hand for gripping a workpiece that is an object of assembly or processing, a chuck, a tool for drilling, grinding, polishing, etc., a painting tool such as a spray gun, and the like.

[0019] The robot 2 has a first joint actuator 27 as a joint part that connects the base 21 and the first arm 23 and rotates the first arm 23 around the first rotation axis J1 with respect to the base 21. Further, the robot 2 has a second joint actuator 28 as a joint part that connects the first arm 23 and the second arm 24 and rotates the second arm 24 around the second rotation axis J2 with respect to the first arm 23.

[0020] The first arm 23 is connected to the base 21 by the first joint actuator 27 at a predetermined distance from the upper surface 210 of the base 21. The second arm 24 is connected to the first arm 23 by the second joint actuator 28 at a predetermined distance from the upper surface 230 of the first arm 23.

[0021] The robot 2 has a first drive mechanism 291 that rotates the spline nut 251 to rotate the spline shaft 253 around the third rotation axis J3. Further, the robot 2 has a second drive mechanism 292 that rotates the ball screw nut 252 to move the spline shaft 253 up and down in the direction along the third rotation axis J3. When the first drive mechanism 291 operates, the spline shaft 253 rotates in a predetermined direction around the third rotation axis J3, and accordingly, the end effector 26 rotates in the same direction. When the second drive mechanism 292 operates, the spline shaft 253 moves in the axial direction of the third rotation axis J3, and accordingly, the end effector 26 moves in the same direction.

[0022] Further, the first joint actuator 27, the second joint actuator 28, the first drive mechanism 291, and the second drive mechanism 292 each have a motor, a speed reducer, an encoder, etc. Among these, each motor and each encoder are electrically connected to the robot control device 9 respectively. Each encoder detects the rotational position information of the corresponding motor and transmits it to the robot control device 9. The robot control device 9 controls the energization conditions for each motor via a motor driver (not shown) based on the rotational position information of each motor received from each encoder. As a result, the first arm 23, the second arm 24, and the spline shaft 253 operate respectively, and the posture of the robot arm 22 changes over time according to a predetermined program, enabling a desired operation to be performed.

[0023] Hereinafter, the motor of the second joint actuator 28 will be referred to as motor 281, the speed reducer of the second joint actuator 28 will be referred to as speed reducer 282, and the encoder of the second joint actuator 28 will be referred to as encoder 283. The motor 281 rotationally drives the second arm 24 around the second rotation axis J2 with respect to the first arm 23. The motor 281 corresponds to the drive unit.

[0024] As shown in FIG. 1, the speed reducer 282, the motor 281, and the encoder 283 are arranged and connected in this order from bottom to top, that is, in the +Z direction. The motor 281 and the encoder 283 are installed in a first installation portion 31, which will be described later. The motor 281 has an output shaft (not shown) on the -Z direction side. The speed reducer 282 is fixed to this output shaft and is also fixed to the first arm 23.

[0025] Next, the structure of the second arm 24 will be described. As shown in FIG. 1, the second arm 24 has a frame 3 composed of a beam-like member forming the basic skeleton of the second arm 24. The frame 3 has a function of supporting and protecting the mounted objects (hereinafter sometimes simply referred to as "mounted objects") mounted on the second arm 24, such as the second joint actuator 28, the first drive mechanism 291, and the second drive mechanism 292 described above.

[0026] As shown in FIGS. 2 and 3, the frame 3 has a plurality of beams, a first installation portion 31, and a second installation portion 32, and is composed of beam-like members combined as appropriate to form a desired three-dimensional shape. In the present embodiment, the plurality of beams include a first beam 33, a second beam 34, a third beam 35, a fourth beam 36, a fifth beam 37, a sixth beam 38, and a seventh beam 39. By making the frame 3 such a beam-like member, the weight of the second arm 24 can be reduced compared to the prior art. Also, even if the frame 3 is a beam-like member, sufficient strength can be ensured for the reasons described later. This will be described in detail below.

[0027] The first installation portion 31 and the second installation portion 32 are arranged to be separated along the horizontal direction, that is, the X-axis direction. The first installation portion 31 is located at the base end portion of the frame 3 and is composed of an annular, particularly circular ring-shaped member having an insertion hole 310 on the inner side. The insertion hole 310 is formed at the center portion of the first installation portion 31 and is a through hole penetrating in the Z-axis direction. As shown in FIG. 4, when viewed in the B direction in FIG. 2, the center of the insertion hole 310 is substantially equal to the center of the entire first installation portion 31 and also coincides with the second rotation axis J2.

[0028] A motor 281 constituting the second joint actuator 28 is installed in the first installation portion 31. Specifically, the first installation portion 31 has an upper surface 311 and an inner peripheral surface 313 of the insertion hole 310, and the shoulder portion of the motor case of the motor 281 is directly or indirectly applied to the upper surface 311 and the inner peripheral surface 313. The motor 281 is fixed in a state where the shoulder portion of the motor case is fitted into the insertion hole 310, for example. Also, the output shaft of the motor 281 passes through the insertion hole 310 without contacting the inner peripheral surface 313 and is fixed to an input shaft (not shown) of the speed reducer 282.

[0029] Since the first installation part 31 is formed of an annular member, particularly an annular member, first, the strength of the first installation part 31 can be increased. In particular, the first installation part 31 that holds the second joint actuator 28 having a considerable large weight can withstand forces such as inertial force, centrifugal force, and impact force received from various directions on the horizontal plane along with the operation of the robot arm 22 with sufficient strength. Second, the motor 281 that constitutes the second joint actuator 28 can be properly held with uniform force over the entire circumference, and the second joint actuator 28 can be stably supported regardless of whether the robot arm 22 is operating or stopped.

[0030] In the present embodiment, the inner edge and the outer edge of the first installation part 31 are circular. However, it is not limited to this configuration. For example, at least one of the inner edge and the outer edge may be elliptical or may be a polygon such as a rectangle.

[0031] Also, the first installation part 31 is not limited to the above configuration. For example, it may be a member on an arc with a part of the annulus cut out, and furthermore, all or part of it may be a plate-shaped, rod-shaped, or net-shaped member.

[0032] The inner diameter of the insertion hole 310 of the first installation part 31 in the present embodiment is constant along the Z-axis direction. However, it is not limited to this configuration, and the inner diameter of the insertion hole 310 may change stepwise or continuously along the Z-axis direction. That is, the shape, dimensions, etc. of the inner peripheral surface 313 of the insertion hole 310 are appropriately determined according to the shape of the motor case of the motor 281 to be held. When the inner diameter of the insertion hole 310 changes stepwise or continuously along the Z-axis direction, the strength of the first installation part 31 itself is improved, and thus the strength of the entire frame 3 is improved.

[0033] The second installation part 32 is located at the tip of the frame 3. A spline nut 251 and a ball screw nut 252 are installed in the second installation part 32. The second installation part 32 includes a first annular member 320, a second annular member 322, and a plurality of connecting members 324. The first annular member 320 is formed of an annular, particularly circular ring-shaped member having an insertion hole 321 on the inside. The second annular member 322 is located in the -Z direction of the first annular member 320 and is formed of an annular, particularly circular ring-shaped member having an insertion hole 323 on the inside. The diameter of the second annular member 322 is smaller than the diameter of the first annular member 320. The insertion hole 321 and the insertion hole 323 are formed at the center of the second installation part 32 and are through holes penetrating in the Z-axis direction. As shown in FIG. 4, when viewed in the B direction in FIG. 2, the centers of the insertion hole 321 and the insertion hole 323 are approximately equal to the center of the entire second installation part 32 and also coincide with the third rotation axis J3.

[0034] The plurality of connecting members 324 are members that connect the first annular member 320 and the second annular member 322. One end of each connecting member 324 is connected to the first annular member 320, and the other end of each connecting member 324 is connected to the second annular member 322. The second installation part 32 of the present embodiment has eight connecting members 324. However, the number of connecting members 324 is not limited to eight.

[0035] The first annular member 320 has a lower surface 325 and an inner peripheral surface 326 of the insertion hole 321. The upper surface of the spline nut 251 is directly or indirectly applied and fixed to the lower surface 325. Note that the upper part of the spline nut 251 may be applied to the inner peripheral surface 326. Also, the spline shaft 253 passes through the insertion hole 321 without contacting the inner peripheral surface 326.

[0036] The second annular member 322 has an upper surface 327 and an inner peripheral surface 328 of the insertion hole 323. The lower part of the ball screw nut 252 is directly or indirectly applied and fixed to the upper surface 327. Note that the lower part of the ball screw nut 252 may be applied to the inner peripheral surface 328. Also, the spline shaft 253 passes through the insertion hole 323 without contacting the inner peripheral surface 328.

[0037] Since the second installation part 32 is composed of an annular first annular member 320 and a second annular member 322, first, the strength of the second installation part 32 can be increased. In particular, the second installation part 32 that holds the work head 25 having a relatively large weight and the end effector 26 on the tip side thereof can withstand various external forces such as inertial force, centrifugal force, and impact force received from all directions on the horizontal plane and the Z-axis direction with sufficient strength during the operation of the robot arm 22. Second, the spline nut 251 and the ball screw nut 252 that constitute the support part can be properly held, and the work head 25 and the like can be stably supported regardless of whether the robot arm 22 is operating or stopped. Therefore, the spline shaft 253 can rotate and move up and down stably without causing play or the like.

[0038] Also, since both the first installation part 31 and the second installation part 32 are composed of annular members, the strength of the lower part of the frame 3 can be further increased.

[0039] Note that, different from the illustrated configuration, the positional relationship between the spline nut 251 and the ball screw nut 252 may be reversed up and down. That is, the ball screw nut 252 may be fixed above the spline nut 251. Even in this case, the same effects as the above-described first and second effects can be exhibited.

[0040] In the second installation part 32 in the present embodiment, the inner edge and the outer edge are circular. However, the present invention is not limited to this configuration. For example, at least one of the inner edge and the outer edge may be elliptical, or may be a polygon such as a rectangle.

[0041] Also, the first annular member 320 and the second annular member 322 are not limited to the above configuration. For example, they may be members on an arc in which a part of the annulus is cut out, and furthermore, all or a part of them may be plate-like members, rod-like or net-like members.

[0042] In this embodiment, the inner diameters of the insertion holes 321 of the first annular member 320 and the insertion holes 323 of the second annular member 322 are constant along the Z-axis direction. However, the present invention is not limited to this configuration, and the inner diameters of the insertion holes 321 and 323 may change stepwise or continuously along the Z-axis direction. That is, the shapes, dimensions, etc. of the inner peripheral surface 326 of the insertion hole 321 and the inner peripheral surface 328 of the insertion hole 323 are appropriately determined according to the shapes of the spline nut 251 and the ball screw nut 252 to be held. When the inner diameters of the insertion holes 321 and 323 change stepwise or continuously along the Z-axis direction, the strength of the second installation portion 32 itself is improved, and thus the strength of the entire frame 3 is improved.

[0043] In this embodiment, the outer diameter of the first annular member 320 is less than the outer diameter of the first installation portion 31. Accordingly, the inner diameter of the insertion hole 321 is less than the inner diameter of the insertion hole 310. As a result, the shape of the portion formed by the first installation portion 31, the first annular member 320 of the second installation portion 32, and the pair of first beams 33 spanned therebetween is tapered from the base end toward the tip end, and the frame 3 achieves an efficient weight distribution without waste while ensuring sufficient strength. However, the present invention is not limited to this, and the inner diameter of the insertion hole 321 may be greater than or equal to the inner diameter of the insertion hole 310. In particular, the pair of first beams 33 may be parallel.

[0044] As shown in FIG. 4, a line segment SL connecting the centers of the first installation portion 31 and the second installation portion 32, that is, a line segment SL connecting the center of the insertion hole 310 and the center of the insertion hole 321 is parallel to the X-axis.

[0045] The first beam 33 is a beam spanned between the first installation portion 31 and the first annular member 320 of the second installation portion 32. That is, the first beam 33 is connected to the first installation portion 31 and the first annular member 320 and fixes the positional relationship between the first installation portion 31 and the first annular member 320. This first beam 33, together with the first installation portion 31 and the first annular member 320, bears the basic skeleton of the lower part of the frame 3. In this embodiment, the first beams 33 are provided in a pair with the line segment SL interposed therebetween when viewed in the B direction.

[0046] The first beam 33 is rod-shaped and is connected to the first installation part 31 at the connection parts 30A and 30B, and is connected to the first annular member 320 at the connection parts 30C and 30D. The first beam 33 has one end connected to the first installation part 31 and the other end connected to the first annular member 320, and is inclined so as to rise in the +Z direction from one end toward the other end. In other words, in the first beam 33, the part closer to the first installation part 31 than the second installation part 32 is located below in the vertical direction, that is, in the -Z direction, compared to the part closer to the second installation part 32 than the first installation part 31. The connection parts 30A and 30B between the first beam 33 and the first installation part 31 are located in the +X direction and the -Z direction with respect to the connection parts 30C and 30D between the first beam 33 and the first annular member 320.

[0047] As shown in FIG. 3, in the following description, among the extending directions of the first beam 33, the direction from the connection part 30A to the connection part 30C, or from the connection part 30B to the connection part 30D may be referred to as the first direction D1, and the direction from the connection part 30C to the connection part 30A, or from the connection part 30D to the connection part 30B may be referred to as the second direction D2.

[0048] Since a support part for supporting the spline shaft 253 is installed at the second installation part 32 located at the tip of the second arm 24, a force FA in the -Z direction is generated due to the self-weight of the spline shaft 253, the support part, and the like. Here, in the first beam 33, since the part closer to the first installation part 31 is located in the -Z direction compared to the part closer to the second installation part 32, the force FA in the -Z direction can be decomposed into a force FA1 in the second direction D2 that compresses the first beam 33 and a force FA2 perpendicular to the force FA1. At this time, at the end of the first beam 33 connected to the first installation part 31, that is, at the connection parts 30A and 30B, a reaction force FB in the first direction D1 that balances the force FA1 that compresses the first beam 33 from the first installation part 31 is generated. That is, the first installation part 31 generates a reaction force FB in the first direction D1 as a reaction force to the force FA1.

[0049] Here, since the first installation part 31 is a part that is rotatably attached to the first arm 23, displacement other than rotation is more likely to be restricted compared to other parts of the second arm 24. In particular, the first installation part 31 is likely to have its displacement in the first direction D1 and the second direction D2 restricted. In addition, since the first arm 23 is located in the second direction D2 with respect to the first installation part 31, the displacement of the first installation part 31 in the second direction D2 is likely to be restricted by the first arm 23.

[0050] In this way, by connecting the first beam 33 to the first installation part 31 whose displacement in the second direction D2 is likely to be restricted, the force FA1 that compresses the first beam 33 can be effectively received by the first installation part 31 and the like, and the rigidity of the second arm 24 in the first direction D1 and the second direction D2 can be enhanced. Further, since the frame 3 of the present embodiment is composed of beam members, the weight of the second arm 24 can be reduced compared to a conventional frame.

[0051] Therefore, it is possible to realize a frame 3 that is more lightweight while ensuring rigidity. That is, it is possible to achieve both an improvement in the strength and a reduction in the weight of the second arm 24. As a result, when the robot 2 performs work, the work speed is improved and the power consumption is reduced.

[0052] As shown in FIG. 4, in the present embodiment, the first beam 33 located on the +Y direction side of the line segment SL is referred to as the "first beam 33A", and the first beam 33 located on the -Y direction side of the line segment SL is referred to as the "first beam 33B". Further, the "lower part of the frame 3" refers to the part composed of the first installation part 31, the second installation part 32, the first beam 33, and the fifth beam 37 and the seventh beam 39 described later, which is located on the -Z direction side of the frame 3.

[0053] The first beams 33A and 33B are linear. The first beams 33A and 33B are inclined with respect to the line segment SL such that the distance between them increases as they proceed in the +X direction.

[0054] In this embodiment, the first beams 33A and 33B are arranged symmetrically with respect to the line segment SL when viewed in the B direction. However, the present invention is not limited to this, and the first beams 33A and 33B may be asymmetrical with respect to the line segment SL.

[0055] The first beam 33A and the first installation part 31, the first beam 33B and the first installation part 31, the first beam 33A and the first annular member 320, and the first beam 33B and the first annular member 320 are directly connected to each other, respectively. These connection parts may be joined by methods such as welding, brazing such as soldering, adhesion with an adhesive, riveting, screwing, bolting, etc., or may be integrally formed by casting. Further, they may be fixed via fixing members (not shown).

[0056] Note that the first beam 33 is not limited to the straight shape as shown in the figure. For example, at least one of the first beams 33A and 33B may have one or two or more curved or bent portions that protrude in the +Z direction side, -Z direction side, +Y direction side, or -Y direction side. For example, the first beams 33A and 33B may have curved or bent portions that approach or connect to each other near the center in their longitudinal directions.

[0057] The first beam 33 may have a shape with a branched portion branched into a plurality of parts in the middle or near the end, or a shape with an intersection portion where a plurality of wire rods intersect. In these cases, one end of the first beam 33 may be connected to the second beam 34, or may be connected to the first installation part 31 or the second installation part 32 via the fourth beam 36 or the fifth beam 37.

[0058] As shown in FIG. 4, the connection part 30A between the first installation part 31 and the first beam 33A is located on the -X direction side of the outer edge of the first installation part 31 and on the +Y direction side with respect to the line segment SL. The connection part 30B between the first installation part 31 and the first beam 33B is located on the -X direction side of the outer edge of the first installation part 31 and on the -Y direction side with respect to the line segment SL.

[0059] In this way, since the first beams 33A and 33B are connected to different positions of the first installation part 31, the strength of the frame 3 can be increased.

[0060] Also, the connection part 30C between the first annular member 320 and the first beam 33A is located on the +Y direction side of the line segment SL among the outer edges of the first annular member 320. The connection part 30D between the first annular member 320 and the first beam 33B is located on the -Y direction side of the line segment SL among the outer edges of the first annular member 320.

[0061] In this way, since the first beams 33A and 33B are connected to different positions of the first annular member 320, the strength of the frame 3 can be increased.

[0062] The second beam 34 is located above the first beam 33 in the vertical direction, that is, in the +Z direction. Similar to the first beam 33, the second beam 34 is connected to the first installation part 31 and the first annular member 320. Specifically, one end of the second beam 34 is connected to the first installation part 31 at the connection parts 30E and 30F, and the other end of the second beam 34 is connected to the first annular member 320 of the second installation part 32 at the connection parts 30C and 30D. The second beam 34 has the function of increasing the strength of the frame 3 and protecting the load carried by the second arm 24.

[0063] As shown in FIG. 4, in this embodiment, the second beam 34 located on the +Y direction side of the line segment SL is referred to as the "second beam 34A", and the second beam 34 located on the -Y direction side of the line segment SL is referred to as the "second beam 34B". In other words, when viewed in the B direction, a pair of the second beam 34A and the second beam 34B are provided with the line segment SL interposed therebetween. With such a configuration, the strength of the frame 3 can be increased.

[0064] The second beam 34 protrudes in the upward vertical direction, i.e., the +Z direction. Specifically, the second beam 34 has an arch shape that curves so as to protrude in the +Z direction and has a protruding portion 340 that protrudes in the +Z direction. Therefore, as shown in FIG. 3, when the second beam 34 is pulled by the -Z direction force FA applied to the second installation portion 32, the direction of the force is converted along the curvature of the second beam 34. That is, at the connection portions 30E and 30F between the second beam 34 and the first installation portion 31, the direction of the force is converted to the direction of pulling the first installation portion 31 in the +Z direction. Here, the first installation portion 31 is connected to the first arm 23 and is likely to be restricted in displacement as described above. Therefore, a reaction force acts on the converted force, i.e., the force pulling the first installation portion 31 in the +Z direction, and the -Z direction force FA applied to the second installation portion 32 can be supported by the first installation portion 31.

[0065] As shown in FIG. 4, in this embodiment, the second beams 34A and 34B have a shape symmetric with respect to the line segment SL when viewed in the B direction. However, the present invention is not limited to this, and the second beams 34A and 34B may be asymmetric with respect to the line segment SL.

[0066] The center of gravity of the frame 3 is unevenly distributed on the side of the first installation portion 31 rather than the center. That is, the center of gravity of the frame 3 is located on the base end side, i.e., the +X direction side, of the midpoint of the line segment SL when viewed in the B direction. Thereby, the weight of the tip side portion of the second arm 24 can be reduced compared to the base end side portion. As a result, the inertial force (inertia) of the rotation of the second arm 24 around the second rotation axis J2 can be reduced. That is, the rotation speed of the second arm 24 can be increased to perform the work more quickly, or the energy required for the rotational drive of the second arm 24 can be reduced.

[0067] The top portions 341 of the protruding portions 340 of the second beams 34A and 34B surround the mounted object so as to store it inside the protruding portion 340 and are positioned at a height that can protect the mounted object well. The top portion 341 of the second beam 34A and the top portion 341 of the second beam 34B are at the same position in the X-axis direction.

[0068] As shown in FIG. 3, each top portion 341 of the second beams 34A and 34B is unevenly distributed toward the first installation portion 31 side from the center. That is, each top portion 341 is located on the proximal end side from the midpoint of the line segment SL when viewed in the B direction.

[0069] In the frame 3, there is a tendency that a relatively large mounted object, that is, a mounted object having a high height in the Z-axis direction, a large width in the Y-axis direction, or both, is disposed at a position unevenly distributed on the +X direction side. In the present embodiment, this mounted object is the second joint actuator 28. Since each top portion 341 is unevenly distributed toward the first installation portion 31 side from the center, such a large mounted object can be surely surrounded and protected so as to be stored between the two protruding portions 340.

[0070] In the second beams 34A and 34B, the portion on the proximal end side from the top portion 341 of the protruding portion 340 has a greater degree of curvature, that is, a greater average value of the curvature of the curvature, than the portion on the distal end side from the top portion 341 of the protruding portion 340. However, the present invention is not limited to this configuration, and the portion on the proximal end side from the top portion 341 of the protruding portion 340 and the portion on the distal end side from the top portion 341 of the protruding portion 340 may have the same average value of the curvature of the curvature, and at least one of them may be linear.

[0071] As shown in FIGS. 2 and 5, each protruding portion 340 of the second beams 34A and 34B has a shape such that the separation distance between them increases as they are separated from the first beams 33A and 33B, that is, the position in the Z-axis direction is on the +Z direction side. Thereby, a relatively large mounted object, such as the motor 281 and the encoder 283, can be stored and disposed in the upper space between the second beams 34A and 34B, particularly between their protruding portions 340, and even such a large mounted object can be sufficiently protected. The distance along the Y-axis between the pair of protruding portions 340 is the largest at the top portion 341.

[0072] Thus, when a relatively large or heavy load is mounted on the proximal end side of the second arm 24, the distal end side portion of the second arm 24 can be made lighter than the proximal end side portion. As a result, the inertial force (inertia) of the rotation of the second arm 24 about the second rotation axis J2 can be reduced. That is, the rotation speed of the second arm 24 can be increased to perform the work more quickly, or the energy required for the rotational drive of the second arm 24 can be reduced.

[0073] The second beam 34A and the first installation portion 31, the second beam 34B and the first installation portion 31, the second beam 34A and the first annular member 320, and the second beam 34B and the first annular member 320 are directly connected to each other. These connection portions may be joined by methods such as welding, brazing such as soldering, adhesion with an adhesive, riveting, screwing, bolting, etc., or may be integrally formed by casting. Further, they may be fixed via a fixing member (not shown).

[0074] The first annular member 320 and the second beam 34A are connected at the same location as the connection portion 30C where the first annular member 320 and the first beam 33A are connected. Also, the first annular member 320 and the second beam 34B are connected at the same location as the connection portion 30D where the first annular member 320 and the first beam 33B are connected. However, it is not limited thereto and they may be connected at another location.

[0075] As shown in FIG. 4, the connection portion 30E between the first installation portion 31 and the second beam 34A is located on the +X direction side of the outer edge of the first installation portion 31 and on the +Y direction side of the line segment SL. The connection portion 30F between the first installation portion 31 and the second beam 34B is located on the +X direction side of the outer edge of the first installation portion 31 and on the -Y direction side of the line segment SL.

[0076] Thus, by connecting the proximal end of the second beam 34A and the proximal end of the second beam 34B to different positions of the first installation portion 31, the strength of the frame 3 can be increased. Note that, different from the illustrated configuration, the proximal end of the second beam 34A and the proximal end of the second beam 34B may be connected to the same location of the first installation portion 31.

[0077] The connection portion 30C between the first annular member 320 and the second beam 34A is located on the +Y direction side of the line segment SL among the outer edges of the first annular member 320. The connection portion 30D between the first annular member 320 and the second beam 34B is located on the -Y direction side of the line segment SL among the outer edges of the first annular member 320.

[0078] In this way, since the tips of the second beam 34A and the second beam 34B are connected to different positions of the first annular member 320, the strength of the frame 3 can be increased. Note that, different from the illustrated configuration, the tips of the second beam 34A and the second beam 34B may be connected to the same location of the first annular member 320.

[0079] The second beam 34 may have a shape with a branched portion branched into a plurality of parts in the middle or near the end, or a shape with an intersection portion where a plurality of wire members intersect. In these cases, one end of the second beam 34 may be connected to the first beam 33, or may be connected to the first installation portion 31 or the first beam 33 via the third beam 35 or the fourth beam 36.

[0080] The third beam 35 reinforces the second beam 34. That is, by installing the third beam 35, the bending shape of the entire second beam 34, particularly the shape of the protruding portion 340, can be more reliably maintained against various external forces applied to the frame 3. Thereby, the strength of the second beam 34, and thus the strength of the entire frame 3, can be sufficiently increased. In the illustrated configuration, the third beam 35 extends along a direction slightly inclined with respect to the Z axis and is substantially linear.

[0081] One end of the third beam 35 is connected to the first installation part 31, and the other end of the third beam 35 is connected to the second beam 34. Therefore, by providing the third beam 35 that connects the first installation part 31 where displacement is likely to be restricted in the second arm 24 and the second beam 34, the rigidity of the second arm 24 is further increased. Also, by suppressing the deflection of the second beam 34, the vibration generated in the second arm 24 when the second arm 24 is driven can be suppressed. Furthermore, in this embodiment, by providing the third beam 35, sufficient strength of the entire frame 3 is ensured.

[0082] The other end of the third beam 35 is located above the first installation part 31, that is, in the +Z direction, and is connected to the second beam 34. The position in the +Z direction of the first installation part 31 indicates the region above the first installation part 31. A force in the -Z direction is generated in the second beam 34 due to its own weight. When the third beam 35 extends along the Z-axis direction, the entire force applied to the third beam 35 due to the weight of the second beam 34 can be received by the first installation part 31. Also, even when the third beam 35 is inclined with respect to the Z-axis direction, the component force of the force applied to the third beam 35 due to the weight of the second beam 34 in the direction along the third beam 35 can be received by the first installation part 31. Note that the smaller the inclination of the third beam 35 with respect to the Z-axis direction, the larger the component force of the force applied to the third beam 35 in the direction along the third beam 35, so it is more effective.

[0083] Furthermore, at this time, since the other end of the third beam 35 is located in the +Z direction of the first installation part 31, in the second beam 34, the distance between the location where the other end of the third beam 35 is connected and the location where it is connected to the first installation part 31 can be made closer. Thereby, the component force of the force applied to the third beam 35 due to the weight of the second beam 34 in the direction intersecting the third beam 35 can also be more easily received by the first installation part 31. Thus, according to this configuration, the weight applied to the second beam 34 by the third beam 35 can be supported more effectively.

[0084] In this embodiment, the other end of the third beam 35 is connected to the top 341 of the second beam 34. Since the other end of the third beam 35 is connected to the top 341 of the second beam 34 which is easily bendable, the bending of the second beam 34 can be further suppressed. Also, in the second beam 34, the strength of the protruding portion 340 which requires relatively high strength, particularly the strength near the top 341, can be increased, and the deformation of the second beam 34 when receiving an external force, and thus the deformation of the entire frame 3 can be more effectively prevented or suppressed. As a result, the load, particularly the load on the first installation portion 31, can be sufficiently protected. Note that the other end of the third beam 35 may be connected to a position deviated from the top 341 as long as it is near the top 341 of the second beam 34.

[0085] As shown in FIG. 4, in this embodiment, the third beam 35 located on the +Y direction side with respect to the line segment SL is referred to as "third beam 35A", and the third beam 35 located on the -Y direction side with respect to the line segment SL is referred to as "third beam 35B". In other words, when viewed in the B direction, a pair of the third beam 35A and the third beam 35B are provided with the line segment SL therebetween. With such a configuration, the strength of the frame 3 can be increased.

[0086] In this embodiment, the third beams 35A and 35B have a shape symmetric with respect to the line segment SL when viewed in the B direction. However, the present invention is not limited thereto, and the third beams 35A and 35B may be asymmetric with respect to the line segment SL.

[0087] One end of the third beam 35 is connected to the location where the first installation portion 31 and the first beam 33 are connected. That is, one end of the third beam 35A is connected to the connection portion 30A between the first installation portion 31 and the first beam 33A, and one end of the third beam 35B is connected to the connection portion 30B between the first installation portion 31 and the first beam 33B. Since one end of the first beam 33 and one end of the third beam 35 are concentrated at the connection portions 30A and 30B, it is easy for an operator to access the inside of the second arm 24 during maintenance of the robot 2. Also, during assembly of the robot 2, it is easy for an assembler to incorporate parts into the second arm 24.

[0088] The third beam 35A and the first installation part 31, the third beam 35B and the first installation part 31, the third beam 35A and the second beam 34A, and the third beam 35B and the second beam 34B are each directly connected. These connection parts may be joined by methods such as welding, brazing such as soldering, adhesion with an adhesive, riveting, screwing, bolting, etc., or may be integrally formed by casting. Further, they may be fixed via fixing members (not shown). Also, they may be indirectly connected via another member, for example, the fourth beam 36 described later and other arbitrary connecting members.

[0089] Note that the third beam 35 is not limited to the straight shape as shown in the figure, and may have one or two or more curved or bent portions protruding in the X-axis direction or the Y-axis direction, for example. Note that conditions such as the dimensions, arrangement, connection points, and number of installed beams of the third beam 35, such as its length and diameter, are not limited to the configuration shown in the figure.

[0090] The fourth beam 36 reinforces the first beam 33 and the second beam 34. That is, by installing the fourth beam 36, the shapes of the first beam 33 and the second beam 34, particularly the shape of the protruding portion 340, can be maintained against various external forces applied to the frame 3. Thereby, the strength of the first beam 33 and the second beam 34, and thus the strength of the entire frame 3, can be sufficiently increased. In the configuration shown in the figure, the fourth beam 36 extends along a direction inclined with respect to the X-axis, Y-axis, and Z-axis and is substantially linear.

[0091] One end of the fourth beam 36 is connected to the first beam 33, and the other end of the fourth beam 36 is connected to the second beam 34. A force in the -Z direction is generated on the first beam 33 due to its own weight. At this time, by connecting one end of the fourth beam 36 to the first beam 33 and connecting the other end of the fourth beam 36 to the second beam 34 located in the +Z direction of the first beam 33, the first beam 33 can be pulled upward by the second beam 34 and the fourth beam 36. Therefore, the deflection of the first beam 33 can be suppressed. That is, with respect to the force generated in the direction of pulling the fourth beam 36 due to the own weight acting on the first beam 33, a force in the direction of compressing the fourth beam 36 is generated by the second beam 34 and the fourth beam 36, so that the distance between the first beam 33 and the second beam 34 can be maintained, and the deflection of the first beam 33 can be suppressed.

[0092] As shown in FIG. 4, in the present embodiment, the fourth beam 36 located on the +Y direction side of the line segment SL is referred to as the "fourth beam 36A", and the fourth beam 36 located on the -Y direction side of the line segment SL is referred to as the "fourth beam 36B". In other words, when viewed in the B direction, a pair of the fourth beam 36A and the fourth beam 36B are provided with the line segment SL interposed therebetween. With such a configuration, the strength of the frame 3 can be increased.

[0093] In the present embodiment, the fourth beams 36A and 36B have a shape symmetric with respect to the line segment SL when viewed in the B direction. However, the present invention is not limited to this, and the fourth beams 36A and 36B may be asymmetric with respect to the line segment SL.

[0094] One end of the fourth beam 36 is connected between the connection portions 30A and 30B with the first installation portion 31 and the connection portions 30C and 30D with the second installation portion 32 of the first beam 33. The first beams 33A and 33B are likely to deflect particularly near the center in the length direction of the first beam 33 between the connection portions 30A and 30B with the first installation portion 31 and the connection portions 30C and 30D with the second installation portion 32. Therefore, by connecting the fourth beam 36 and the first beam 33 near the center of the first beam 33, the deflection of the first beam 33 can be further suppressed.

[0095] The other end of the fourth beam 36 is connected to the top 341 of the second beam 34. One end of a third beam 35, whose other end is connected to a first installation part 31 where displacement in the second direction D2 is liable to be restricted in the second arm 24, is also connected to the top 341 of the second beam 34. Therefore, the top 341 of the second beam 34 is less likely to deflect in the -Z direction. Incidentally, if the other end of the fourth beam 36 is in the vicinity of the top 341 of the second beam 34, it may be connected to a location displaced from the top 341.

[0096] The fourth beam 36A and the first beam 33A, the fourth beam 36B and the first beam 33B, the fourth beam 36A and the second beam 34A, and the fourth beam 36B and the second beam 34B are directly connected respectively. These connection parts may be joined by methods such as welding, brazing such as soldering, adhesion with an adhesive, riveting, screwing, bolting, etc., or may be integrally formed by casting. Further, they may be fixed via fixing members (not shown).

[0097] Incidentally, the fourth beam 36 is not limited to the straight shape as shown in the figure, and may have, for example, one or two or more curved or bent portions protruding in the X-axis direction, Y-axis direction, or Z-axis direction. Incidentally, conditions such as dimensions such as the length and diameter of the fourth beam 36, arrangement, connection locations, number of installations, etc. are not limited to the configuration shown in the figure.

[0098] The fifth beam 37 extends along a direction inclined with respect to the X-axis, Y-axis, and Z-axis and is substantially linear. One end of the fifth beam 37 is connected between connection parts 30A, 30B with the first installation part 31 and connection parts 30C, 30D with the second installation part 32 in the first beam 33. The other end of the fifth beam 37 is connected to a portion located below, that is, in the -Z direction, than connection parts 30C, 30D of the second installation part 32 with the first beam 33. Specifically, the other end of the fifth beam 37 is connected to the second annular member 322 of the second installation part 32. By having the fifth beam 37, the second installation part 32 that supports the spline shaft 253 can be supported by a plurality of beams including the first beam 33, the second beam 34, and the fifth beam 37, and thus the spline shaft 253 can be supported more stably.

[0099] As shown in FIG. 4, in the present embodiment, the fifth beam 37 located on the +Y direction side of the line segment SL is referred to as the "fifth beam 37A", and the fifth beam 37 located on the -Y direction side of the line segment SL is referred to as the "fifth beam 37B". In other words, when viewed in the B direction, a pair of the fifth beam 37A and the fifth beam 37B are provided with the line segment SL interposed therebetween. With such a configuration, the strength of the frame 3 can be increased.

[0100] As shown in FIG. 4, the connection portion 30G between the fifth beam 37A and the second annular member 322 is located on the +Y direction side of the line segment SL among the outer edges of the second annular member 322. The connection portion 30H between the fifth beam 37B and the second annular member 322 is located on the -Y direction side of the line segment SL among the outer edges of the second annular member 322.

[0101] In this way, since the fifth beam 37A and the fifth beam 37B are connected to different positions of the second annular member 322, the strength of the frame 3 can be increased.

[0102] In the present embodiment, the fifth beams 37A and 37B have a shape symmetric with respect to the line segment SL when viewed in the B direction. However, the present invention is not limited to this, and the fifth beams 37A and 37B may be asymmetric with respect to the line segment SL.

[0103] The fifth beam 37A and the first beam 33A, the fifth beam 37B and the first beam 33B, the fifth beam 37A and the second annular member 322, and the fifth beam 37B and the second annular member 322 are directly connected to each other. These connection portions may be joined by methods such as welding, brazing such as soldering, adhesion with an adhesive, riveting, screwing, bolting, etc., or may be integrally formed by casting. Further, they may be fixed via a fixing member (not shown).

[0104] Note that the fifth beam 37 is not limited to the straight shape as shown in the figure, and for example, it may have one or two or more curved or bent portions protruding in the Y-axis direction or the Z-axis direction. Note that conditions such as dimensions such as the length and diameter of the fifth beam 37, the arrangement, the connection location, and the number of installations are not limited to the illustrated configuration.

[0105] The sixth beam 38, similar to the third beam 35, reinforces the second beam 34. That is, by installing the sixth beam 38, the bending shape of the entire second beam 34 can be maintained against various external forces applied to the frame 3. Thereby, the strength of the second beam 34, and thus the strength of the entire frame 3, can be sufficiently increased. In the illustrated configuration, the sixth beam 38 extends along a direction slightly inclined with respect to the Z-axis and is substantially linear. Also, in the illustrated configuration, four sixth beams 38 are provided. Note that the sixth beam 38 can be regarded as a part of the third beam 35.

[0106] One end of the sixth beam 38 is connected to the first installation portion 31, and the other end is connected to the second beam 34. Since the sixth beam 38 serves as a strut with respect to the first installation portion 31 and the second beam 34, it is possible to suppress the deflection of the second beam 34 and suppress the vibration generated in the second arm 24 when the second arm 24 is rotationally driven. That is, by installing each sixth beam 38, the strength of the entire frame 3 is sufficiently ensured.

[0107] The other end of the sixth beam 38 is connected to the second beam 34 at the position in the +Z direction of the first installation portion 31. Since the sixth beam 38 extends in the +Z direction from the first installation portion 31, which has high rigidity in the second arm 24, it is possible to transmit a force in the opposite direction from the sixth beam 38 to the second beam 34 against the -Z direction force generated by the self-weight of the second beam 34. Therefore, the second beam 34 can be supported by the sixth beam 38. With such a configuration, the strength of the protruding portion 340, which requires relatively high strength among the second beams 34, can be increased, and the deformation of the second beam 34 when receiving an external force, and thus the deformation of the entire frame 3, can be more effectively prevented or suppressed. As a result, the load, particularly the load on the first installation portion 31, can be sufficiently protected.

[0108] One end of the sixth beam 38 is connected to the location where the first beam 33 and the first installation portion 31 are connected, and the location where the third beam 35 and the first installation portion 31 are connected. That is, one end of the sixth beam 38 is connected to the connection portions 30A and 30B.

[0109] As shown in FIG. 4, in the present embodiment, the sixth beam 38 located on the +Y direction side of the line segment SL is referred to as the "sixth beam 38A", and the sixth beam 38 located on the -Y direction side of the line segment SL is referred to as the "sixth beam 38B". In other words, when viewed in the B direction, a pair of the sixth beam 38A and the sixth beam 38B are provided with the line segment SL interposed therebetween. With such a configuration, the strength of the frame 3 can be increased.

[0110] In the present embodiment, the sixth beams 38A and 38B have a shape symmetric with respect to the line segment SL when viewed in the B direction. However, the present invention is not limited to this, and the sixth beams 38A and 38B may be asymmetric with respect to the line segment SL.

[0111] The sixth beam 38A and the first installation portion 31, the sixth beam 38B and the first installation portion 31, the sixth beam 38A and the second beam 34A, and the sixth beam 38B and the second beam 34B are directly connected to each other, respectively. These connection portions may be joined by methods such as welding, brazing such as soldering, adhesion with an adhesive, riveting, screwing, bolting, etc., or may be integrally formed by casting. Further, they may be fixed via a fixing member (not shown).

[0112] Note that the sixth beam 38 is not limited to the straight shape as shown in the figure, and may have, for example, one or two or more curved or bent portions protruding in the X-axis direction or the Y-axis direction.

[0113] Further, between the first beam 33 and the second beam 34, instead of the third beam 35 and the sixth beam 38, other connection members connecting the first beam 33 and the second beam 34 may be provided. Examples of such a connection member include a lattice member, a net-like member, a honeycomb structure, a porous body, a plate-like member having a plurality of small holes or slits penetrating in the plate thickness direction, and the like. Note that the conditions such as the dimensions, arrangement, connection locations, and number of installations of the sixth beam 38, such as the length and diameter, are not limited to the configuration shown in the figure.

[0114] The seventh beam 39 connects the first beam 33A and the first beam 33B. By installing the seventh beam 39, the strength of the lower part of the frame 3 can be increased, and thus the strength of the entire frame 3 can be increased. In the illustrated configuration, two seventh beams 39 are provided.

[0115] The seventh beam 39 is connected to the first beam 33, the first installation portion 31, and the second annular member 322. These connection portions may be joined by methods such as welding, brazing such as soldering, adhesion with an adhesive, riveting, screwing, bolting, etc., or may be integrally formed by casting. Further, it may be fixed via a fixing member (not shown).

[0116] Further, the seventh beam 39 has a function of placing and fixing the load carried by the second arm 24, such as the second joint actuator 28, the first drive mechanism 291, and the second drive mechanism 292, on its upper part.

[0117] With such a seventh beam 39, the strength of the entire frame 3, particularly the strength of the lower part of the frame 3, can be increased, and the load can be supported more stably. In particular, when the frame 3 receives a torsional external force centered on the line segment SL, the strength to resist it can be increased.

[0118] Note that the seventh beam 39 may have a shape with a branched portion branched into a plurality in the middle or near the end, or a shape with an intersection portion where a plurality of wire rods intersect. Note that the conditions such as the dimensions (length, diameter, etc.), arrangement, connection location, and number of installations of the seventh beam 39 are not limited to the illustrated configuration.

[0119] Among the plurality of beams constituting the frame 3 of the second arm 24, that is, the first beam 33, the second beam 34, the third beam 35, the fourth beam 36, the fifth beam 37, the sixth beam 38, and the seventh beam 39, the number of beams connected to the first installation portion 31 is larger than the number of beams connected to the second installation portion 32. Since the first installation portion 31 is the location connected to the first arm 23 connected to the base 21, displacement is likely to be restricted. By increasing the number of beams connected to the first installation portion 31 where displacement is likely to be restricted, the rigidity of the second arm 24 can be further enhanced.

[0120] Each of the members of the first installation portion 31, the second installation portion 32, the first beam 33, the second beam 34, the third beam 35, the fourth beam 36, the fifth beam 37, the sixth beam 38, and the seventh beam 39 may be constituted by a solid body or a hollow body, respectively. Alternatively, a solid body and a hollow body may be appropriately combined. When constituted by a solid body, the strength of the member and the frame 3 can be further enhanced. When constituted by a hollow body, while ensuring sufficient strength of the member and the entire frame 3, further weight reduction of the frame 3 can be achieved.

[0121] As materials for the components constituting the frame 3, such as the first installation part 31, the second installation part 32, the first beam 33, the second beam 34, the third beam 35, the fourth beam 36, the fifth beam 37, the sixth beam 38, and the seventh beam 39, composite materials based on aluminum or aluminum alloy or magnesium are preferred in order to achieve both improved strength and weight reduction of the frame 3. As other materials, for example, iron-based alloys such as iron or stainless steel, copper or copper-based alloys, various metal materials such as titanium or titanium-based alloys, various ceramic materials, polyesters such as polyethylene, polypropylene, polystyrene, and polyethylene terephthalate, acrylic resins such as polycarbonate and polymethyl methacrylate, various resin materials (especially hard resin materials) such as polyamide and fluororesin, high-strength fiber materials such as aramid, Kevlar (registered trademark), Zylon (registered trademark), metal fiber, and carbon fiber or materials containing them (such as fiber-reinforced plastics), various ceramic materials, various carbon materials, etc. can be mentioned. Also, a composite material obtained by arbitrarily combining two or more of these may be used. All of the above components may be made of the same material, or some may be made of materials different from others.

[0122] Each component constituting the frame 3 may be in a state where residual stress generated during, for example, molding, processing, connection by welding, etc., or assembly remains, or may be in a state where the residual stress is removed or relaxed by, for example, heat treatment. In the former case, by mainly having a state of compressive residual stress, the strength of the entire frame 3 can be further increased, which is preferable. In the latter case, by mainly removing tensile residual stress, the joint strength of the joint part and the strength of the entire frame 3 can be further increased, which is preferable.

[0123] Each component constituting the frame 3, that is, the first installation part 31, the second installation part 32, the first beam 33, the second beam 34, the third beam 35, the fourth beam 36, the fifth beam 37, the sixth beam 38, the seventh beam 39, etc. can be manufactured through various cold or hot plastic working methods such as rolling, forging, press forming, compression molding, extrusion molding, drawing molding, wire drawing, punching, bending, etc., casting, injection molding, hot isostatic pressing (HIP), cold isostatic pressing (CIP), machining, grinding, milling, electrical discharge machining, laser machining, 3D printer shaping, powder sintering, metal injection molding (MIM), etc., or a method in which these are appropriately combined. Further, various molds such as a press working die and an injection molding die may be produced by 3D printer shaping, and a beam-shaped member or each component thereof may be manufactured using this mold.

[0124] As described above, the robot 2 of the present embodiment includes a base 21, a first arm 23 rotatably connected to the base 21 around a first rotation axis J1, a frame 3, and a second arm 24 rotatably connected to the first arm 23 around a second rotation axis J2 parallel to the first rotation axis J1. The robot 2 further includes a motor 281 that rotationally drives the second arm 24 around the second rotation axis J2 with respect to the first arm 23, a spline shaft 253 disposed at a position horizontally spaced from the second rotation axis J2 in the second arm 24, and a spline nut 251 and a ball screw nut 252 that movably support the spline shaft 253. The frame 3 includes a plurality of beams, a first installation part 31 where the motor 281 is installed, and a second installation part 32 where the spline nut 251 and the ball screw nut 252 are installed. The plurality of beams include a first beam 33 connected to the first installation part 31 and the second installation part 32, and a second beam 34 connected to the first installation part 31 and the second installation part 32, located above the first beam 33 in the vertical direction and having a shape protruding upward. Among the first beam 33, the portion closer to the first installation part 31 than the second installation part 32 is located below the portion closer to the second installation part 32 than the first installation part 31 in the vertical direction.

[0125] According to the present embodiment, for the reasons described above, it is possible to realize the frame 3 that is more lightweight while ensuring rigidity. That is, it is possible to achieve both an improvement in the strength and a reduction in the weight of the second arm 24. As a result, when the robot 2 performs work, it contributes to an improvement in the work speed and a reduction in power consumption.

[0126] 2. Second Embodiment In the robot 2 of the present embodiment, the shape of the frame 3 of the second arm 24 is different from that of the first embodiment. Regarding the same configuration as the first embodiment, duplicate explanations will be omitted.

[0127] FIG. 6 is a perspective view showing the frame 3 of the second arm 24 according to the second embodiment. FIG. 7 is a side view of the frame 3 as viewed in the D direction in FIG. 6.

[0128] As shown in FIGS. 6 and 7, the frame 3 of the second arm 24 according to the second embodiment has a second beam 43 composed of a plurality of linear beams. The second beam 43 is formed in a V shape protruding in the +Z direction by connecting a linear first member 431 and a linear second member 432. In other words, the linear first member 431 and the linear second member 432 are connected at a predetermined angle. The predetermined angle is preferably in the range of 60 degrees to 150 degrees, and more preferably 100 degrees. One end of the first member 431 is connected to the first annular member 320 of the second installation portion 32, and the other end of the first member 431 is connected to one end of the second member 432. The other end of the second member 432 is connected to the first installation portion 31.

[0129] As shown in FIG. 6, in the present embodiment, the second beam 43 located on the +Y direction side of the line segment SL is referred to as the "second beam 43A", the first member 431 located on the +Y direction side of the line segment SL is referred to as the "first member 431A", and the second member 432 located on the +Y direction side of the line segment SL is referred to as the "second member 432A". Further, the second beam 43 located on the -Y direction side of the line segment SL is referred to as the "second beam 43B", the first member 431 located on the -Y direction side of the line segment SL is referred to as the "first member 431B", and the second member 432 located on the -Y direction side of the line segment SL is referred to as the "second member 432B". In other words, when viewed in the E direction, a pair of the second beam 43A and the second beam 43B are provided with the line segment SL interposed therebetween. With such a configuration, the strength of the frame 3 can be increased.

[0130] The connection point between the other end of the first member 431A and one end of the second member 432A is the top 430 of the second beam 43A, and the connection point between the other end of the first member 431B and one end of the second member 432B is the top 430 of the second beam 43B.

[0131] Similar to the first embodiment, one end of the third beam 35 is connected to the first installation portion 31, and the other end of the third beam 35 is connected to the top 430 of the second beam 43. That is, the third beam 35A and the second beam 43A are connected at the top 430 of the second beam 43A, and the third beam 35B and the second beam 43B are connected at the top 430 of the second beam 43B. Also, the fourth beam 36A and the second beam 43A are connected at the top 430 of the second beam 43A, and the fourth beam 36B and the second beam 43B are connected at the top 430 of the second beam 43B.

[0132] The frame 3 of the second arm 24 has an eighth beam 44 connected to the top 430 of the second beam 43A and the top 430 of the second beam 43B. The eighth beam 44 extends along the Y-axis and is linear. The length of the eighth beam 44 in the Y-axis direction is longer than the diameter of the first annular member 320 of the second installation portion 32. And the length of the eighth beam 44 in the Y-axis direction is longer than the diameter of the first installation portion 31. Note that the frame 3 may not have the eighth beam 44.

[0133] The second beam 43 may be formed by joining a first member 431 and a second member 432 by welding or the like, or may be formed in a V shape by bending a single beam member.

[0134] As described above, according to the second embodiment, in addition to the effects of the first embodiment, the following effects can be obtained.

[0135] The second beam 43 is composed of two straight beams, namely a first member 431 and a second member 432, and the two beams are connected at a predetermined angle. Therefore, compared with the arched second beam 34, the manufacturing becomes easier.

[0136] Further, the third beam 35 is connected to the top 430 of the second beam 43. Although the top 430 of the second beam 43 is easily deflected in the -Z direction due to its own weight, the connection of the third beam 35 to the top 430 of the second beam 43 can further suppress the deflection of the second beam 43.

[0137] In addition, in the first embodiment and the second embodiment described above, the second arm 24 may have a cover (not shown) that is detachably attached to the frame 3. When this cover is attached to the frame 3, the frame 3 and the mounted object are covered by the cover, preventing the intrusion of dust, dirt, etc. As this cover, for example, a transparent or opaque plastic cover, that is, a cover that is relatively lightweight but has sufficient strength can be used.

[0138] On the other hand, in the first embodiment and the second embodiment described above, no cover is attached to the frame 3. This has a first advantage that the trouble of attaching and detaching the cover can be saved, a second advantage that the second arm 24 can be further lightened by the weight of the cover, and a third advantage that the heat dissipation property of the second arm 24, particularly the heat dissipation property of the mounted object on the second arm 24, is excellent.

[0139] Note that the configuration of the frame 3 described above may be applied not only to the second arm 24 but also to the frame of the first arm 23. This can further reduce the weight of the entire robot arm 22, contributing to an improvement in the working speed and a reduction in power consumption.

[0140] As described above, the robot 2 of the present invention has been described based on the illustrated embodiment. However, the present invention is not limited thereto, and the configuration of each part can be replaced with any configuration having the same function. Further, other arbitrary components may be added to the robot 2 of the present invention.

Explanation of Reference Numerals

[0141] 1... Robot system, 2... Robot, 3... Frame, 9... Robot control device, 10... Floor surface, 21... Base, 22... Robot arm, 23... First arm, 24... Second arm, 25... Working head, 26... End effector, 27... First joint actuator, 28... Second joint actuator, 30A, 30B, 30C, 30D, 30E, 30F, 30G, 30H... Connection part, 31... First installation part, 32... Second installation part, 33, 33A, 33B... First beam, 34, 34A, 34B... Second beam, 35, 35A, 35B... Third beam, 36, 36A, 36B... Fourth beam, 37, 37A, 37B... Fifth beam, 38, 38A, 38B... Sixth beam, 39... Seventh beam, 43, 43A, 43B... Second beam, 44... Eighth beam, 210... Upper surface, 230... Upper surface, 251... Spline nut, 252... Ball screw nut, 253... Spline shaft, 281... Motor, 282... Reducer, 283... Encoder, 291... First drive mechanism, 292... Second drive mechanism, 310... Insertion hole, 311... Upper surface, 313... Inner peripheral surface, 320... First annular member, 321... Insertion hole, 322... Second annular member, 323... Insertion hole, 324... Connecting member, 325... Lower surface, 326... Inner peripheral surface, 327... Upper surface, 328... Inner peripheral surface, 340... Protrusion, 341... Top, 430... Top, 431, 431A, 431B... First member, 432, 432A, 432B... Second member, D1... First direction, D2... Second direction, FA, FA1, FA2... Force, FB... Reaction force, J1... First rotation axis, J2... Second rotation axis, J3... Third rotation axis, SL... Line segment.

Claims

1. A base, a first arm rotatably connected to the base about a first rotation axis, a second arm having a frame and rotatably connected to the first arm about a second rotation axis parallel to the first rotation axis, a driving unit for rotationally driving the second arm about the second rotation axis with respect to the first arm, a shaft disposed at a position spaced horizontally from the second rotation axis in the second arm, and a support unit for movably supporting the shaft, wherein the frame has a plurality of beams, a first installation part where the driving unit is installed, and a second installation part where the support unit is installed, wherein the plurality of beams include a first beam connected to the first installation part and the second installation part, and a second beam connected to the first installation part and the second installation part, located above the first beam in the vertical direction and protruding upward, and in the first beam, a portion closer to the first installation part than the second installation part is located below the portion closer to the second installation part than the first installation part in the vertical direction. The robot is characterized by this.

2. The plurality of beams include a third beam, and one end of the third beam is connected to the first installation part, and the other end of the third beam is connected to the second beam. The robot according to claim 1 is characterized by this.

3. The other end of the third beam is located above the first installation part. The robot according to claim 2 is characterized by this.

4. One end of the third beam is connected to a connection part between the first installation part and the first beam. The robot according to claim 2 is characterized by this.

5. The plurality of beams include a fourth beam, and one end of the fourth beam is connected to the first beam, and the other end of the fourth beam is connected to the second beam. The robot according to claim 1 is characterized by this.

6. One end of the fourth beam is connected between a connection part of the first beam with the first installation part and a connection part of the first beam with the second installation part. The robot according to claim 5 is characterized by this.

7. Among the plurality of beams, the number of beams connected to the first installation part is larger than the number of beams connected to the second installation part. The robot according to claim 1 is characterized by this.

8. The second beam is arch-shaped. The robot according to any one of claims 1 to 7 is characterized by this.

9. The second beam is arch-shaped, The robot according to any one of claims 2 to 4, wherein the other end of the third beam is connected to the top of the second beam.

10. The second beam is composed of two straight beams, The robot according to any one of claims 1 to 7, wherein the two beams are connected at a predetermined angle.

11. The second beam is composed of two straight beams, The two beams are connected at a predetermined angle, The robot according to any one of claims 2 to 4, wherein the other end of the third beam is connected to the top of the second beam.

12. The plurality of beams includes a fifth beam, One end of the fifth beam is connected between the connection portion of the first beam with the first installation portion and the connection portion of the first beam with the second installation portion, The robot according to claim 1, wherein the other end of the fifth beam is connected to a portion of the second installation portion that is located below the connection portion with the first beam.

Images