Robot joint mechanism, robot, and method for assembling robot joint mechanism

Abstract

To provide a robot joint mechanism capable of suppressing reduction of assembling accuracy and a method for assembling the robot joint mechanism.SOLUTION: This robot joint mechanism comprises: a through-hole; a robot component provided with first and second holes arranged around the through-hole; a motor screwed by using the first hole and having an output shaft inserted into the through-hole; and a wave motion gear screwed by using the second hole and provided with a wave generator connected to the output shaft. The diameter of the through-hole is smaller than that of the wave generator.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a robot joint mechanism, a robot, and an assembling method of a robot joint mechanism.

Background Art

[0002] Patent Document 1 describes a robot joint mechanism having a motor fixed to a fixed frame, and a harmonic gear device having an input side connected to the motor and an output side fixed to a movable frame. Further, the harmonic gear device mainly includes a wave generator, a flex spline, and a circular spline.

[0003] Such a robot joint mechanism is usually assembled by steps of preparing a first unit formed by fixing a flex spline and a circular spline to a fixed frame and a movable frame, and a second unit formed by fixing a wave generator to an output shaft of a motor, and inserting the wave generator into the flex spline through a through hole formed in the fixed frame and fixing the motor to the fixed frame.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] As described above, in the assembly of the robot joint mechanism, since it is necessary to insert the wave generator into the through hole formed in the fixed frame, the diameter of the through hole must be made larger than the major axis of the wave generator. On the other hand, screw holes for fixing the motor are formed in the fixed frame. However, since the minimum diameter of the through hole is limited to be equal to or greater than the major axis of the wave generator, it is not possible to form the screw holes closer to the central axis of the robot joint mechanism any further.

[0006] Therefore, for example, when the motor is small relative to the wave generator, fixing the motor to the fixed frame becomes a problem. For example, a method of interposing a relay member for connecting both between the motor and the fixed frame can be considered. However, as the number of parts increases, tolerances are accumulated, assembly accuracy decreases, and excessive stress unintended for the robot joint mechanism may be applied, leading to a reduction in the lifespan of the robot joint mechanism. On the other hand, if component accuracy is increased to reduce tolerances in order to improve assembly accuracy, there is a risk that the yield rate will decrease and manufacturing costs will increase.

Means for Solving the Problem

[0007] The robot joint mechanism of the present invention includes a robot component having a through hole, a first hole and a second hole disposed around the through hole, a motor screwed using the first hole and having an output shaft inserted through the through hole, and a harmonic drive device screwed using the second hole and having a wave generator connected to the output shaft. The diameter of the through hole is smaller than the major axis of the wave generator.

[0008] The robot of the present invention includes a first member, a second member, and a robot joint mechanism that connects the first member and the second member and rotates the second member with respect to the first member. The robot joint mechanism is A robot component including a through hole, a first hole and a second hole arranged around the through hole. A motor screwed using the first hole and having an output shaft inserted through the through hole. A harmonic gear device including a flex spline and a circular spline which are parts of the harmonic gear device and are screwed using the second hole and connected to the output shaft. The diameter of the through hole is smaller than the major diameter of the wave generator.

[0009] The assembling method of the robot joint mechanism of the present invention includes a preparation step of preparing a robot component including a through hole, a first hole and a second hole arranged around the through hole, An output shaft insertion step of inserting the output shaft of the motor through the through hole from one side of the robot component, A connection step of connecting, from the other side of the robot component, a wave generator which is a part of the harmonic gear device and has a major diameter larger than the diameter of the through hole to the output shaft, An arrangement step of arranging, from the other side of the robot component, a flex spline and a circular spline which are parts of the harmonic gear device, A first fixing step of screwing the harmonic gear device to the robot component using the second hole from one side of the robot component, A second fixing step of screwing the motor to the robot component using the first hole from one side of the robot component.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

Figure 18

Figure 19

Embodiments for Carrying Out the Invention

[0011] Hereinafter, the robot joint mechanism, robot, and assembly method of the robot joint mechanism of the present invention will be described in detail based on the embodiments shown in the accompanying drawings. For convenience of explanation, in the following, the upper side of FIG. 2 is defined as the upper side, and the lower side is defined as the lower side. The other figures shall also follow the up and down directions defined in FIG. 2.

[0012] FIG. 1 is a side view of a robot according to the first embodiment. FIG. 2 is a cross-sectional view of a robot joint mechanism included in the robot of FIG. 1. FIG. 3 is a bottom view of a flange included in the robot joint mechanism of FIG. 2. FIG. 4 is a bottom view of the robot joint mechanism. FIG. 5 is a cross-sectional view of a conventional robot joint mechanism. FIG. 6 is a flowchart showing an assembly process of the robot joint mechanism. FIGS. 7 to 13 are cross-sectional views for explaining an assembly method of the robot joint mechanism, respectively. FIGS. 14 to 17 are bottom views for explaining an assembly method of the robot joint mechanism, respectively. FIG. 18 is a cross-sectional view for explaining an assembly method of the robot joint mechanism. Note that FIG. 2 is a cross-sectional view taken along line A-A in FIG. 3.

[0013] The robot 1 shown in FIG. 1 is a scalar robot (horizontal articulated robot), and is used, for example, in various operations such as holding, transporting, assembling, and inspecting a workpiece such as an electronic component. However, the configuration and use of the robot 1 are not particularly limited, respectively.

[0014] The robot 1 includes a base 2 fixed to the floor surface and an arm 3 connected to the base 2. The arm 3 includes a first arm 31 whose proximal end is connected to the base 2 and rotates about a first rotation axis J1 along the vertical direction with respect to the base 2, and a second arm 32 whose proximal end is connected to the distal end of the first arm 31 and rotates about a second rotation axis J2 along the vertical direction with respect to the first arm 31. The first rotation axis J1 and the second rotation axis J2 are parallel.

[0015] A work head 33 is provided at the distal end of the second arm 32. The work head 33 includes a spline nut 331 and a ball screw nut 332 coaxially arranged at the distal end of the second arm 32, and a spline shaft 333 inserted through the spline nut 331 and the ball screw nut 332. The spline shaft 333 is rotatable about a third rotation axis J3 which is the central axis thereof and along the vertical direction with respect to the second arm 32, and is movable up and down along the third rotation axis J3. The third rotation axis J3 is parallel to the first rotation axis J1 and the second rotation axis J2.

[0016] An end effector 34 is attached to the lower end of the spline shaft 333. The end effector 34 is detachable, and an appropriate one suitable for the target work is selected as appropriate. Examples of the end effector 34 include a hand that holds a workpiece by clamping or suction, a working tool that performs predetermined processing on the workpiece, and the like.

[0017] In addition, the robot 1 includes a robot joint mechanism 51 that connects the base 2 and the first arm 31 and rotates the first arm 31 around the first rotation axis J1 with respect to the base 2, and a robot joint mechanism that connects the first arm 31 and the second arm 32 and rotates the second arm 32 around the second rotation axis J2 with respect to the first arm 31. 52. The robot 1 also includes a drive device 53 that rotates the spline nut 331 to rotate the spline shaft 333 around the third rotation axis J3, and a drive device 54 that rotates the ball screw nut 332 to move the spline shaft 333 up and down along the third rotation axis J3.

[0018] The robot 1 also includes a robot control device 4 that is disposed inside the base 2 and controls the driving of the robot joint mechanisms 51 and 52 and the drive devices 53 and 54 based on commands from a host computer (not shown). By the robot control device 4 independently controlling the robot joint mechanisms 51 and 52 and the drive devices 53 and 54, the robot 1 can be made to perform a desired operation.

[0019] The robot control device 4 is composed of, for example, a computer, and includes a processor that processes information, a memory communicably connected to the processor, and an external interface. In addition, various programs executable by the processor are stored in the memory, and the processor can read and execute various programs and the like stored in the memory.

[0020] The overall configuration of the robot 1 has been briefly described above. Next, the robot joint mechanisms 51 and 52 provided in the robot 1 will be described in detail. Note that since the robot joint mechanisms 51 and 52 have the same configuration except for their different arrangements, the robot joint mechanism 51 will be described in detail below, and the description of the robot joint mechanism 52 will be omitted.

[0021] As shown in FIG. 2, the robot joint mechanism 51 includes a flange 9, a motor 6 disposed on the lower surface side of the flange 9, an encoder 8 disposed below the motor 6, and a harmonic gear device 7 disposed on the upper surface side of the flange 9. In the following, the rotation axis of the shaft 61 of the motor 6 is defined as the central axis A1 of the robot joint mechanism 51. This central axis A1 constitutes the first rotation axis J1 of the robot 1.

[0022] ≪Flange 9≫ The flange 9 is a robot component that forms a part of the robot 1, supports the motor 6 and the harmonic gear device 7, and is a member for fixing the robot joint mechanism 51 to the base 2. That is, the motor 6 and the harmonic gear device 7 are fixed to the base 2 via the flange 9. However, the robot component is not limited to the flange 9, and for example, the base 2 may be used. That is, in the present embodiment, the motor 6 and the harmonic gear device 7 are fixed to the base 2 via the flange 9, but it is not limited thereto, and the motor 6 and the harmonic gear device 7 may be directly fixed to the base 2. Thereby, the number of parts of the robot 1 can be reduced. And since the number of parts is reduced, the fastening of screws is eliminated, and the rigidity can be improved. Also, the number of assembly steps can be reduced.

[0023] As shown in FIG. 2, a through hole 90 is formed in the central portion of the flange 9, and the shaft 61 of the motor 6 is inserted into the through hole 90 from below. The through hole 90 is substantially circular with the central axis A1 as the center. However, the shape of the through hole 90 is not particularly limited.

[0024] Also, the diameter R of the through hole 90 90is smaller than the major axis R of the wave generator 71 of the harmonic gear device 7. That is, R 71 is smaller. That is, R 90 < R 71 That is, in a plan view from the direction along the central axis A1, the through hole 90 overlaps with the wave generator 71. As a result, as shown in the figure, even a motor 6 that is smaller in size than the harmonic gear device 7 can be fixed to the flange 9 without using a conventional relay member. Therefore, a decrease in the mounting accuracy of the motor 6 to the flange 9 is suppressed, and a deviation of the central axis A1 can be effectively suppressed. In addition, since there is no relay member, the tolerances of the flange 9 and the housing 63 can be set more generously, which suppresses a decrease in the yield rate and leads to a decrease in the manufacturing cost. The effects will be described in detail later.

[0025] Also, as shown in FIG. 2, the flange 9 is formed with a first hole 91 for fixing the motor 6 to the lower surface of the flange 9, a second hole 92 for fixing the harmonic gear device 7 to the upper surface of the flange 9, and a third hole 93 for fixing the flange 9 to the base 2 as a first member. Among these, the first hole 91 is a threaded hole (female thread) into which the first bolt B1 is screwed and inserted, and the second hole 92 and the third hole 93 are through holes through which the second bolt B2 and the third bolt B3 are inserted and penetrate the upper and lower surfaces.

[0026] As shown in FIG. 3, four first holes 91 are arranged at substantially equal intervals along a virtual circle C1 with a radius r1 centered on the central axis A1 so as to surround the periphery of the through hole 90. Sixteen second holes 92 are arranged at substantially equal intervals along a virtual circle C2 with a radius r2 centered on the central axis A1 so as to surround the periphery of the through hole 90. Six third holes 93 are arranged at substantially equal intervals along a virtual circle C3 with a radius r3 centered on the central axis A1 so as to surround the periphery of the through hole 90.

[0027] Thus, by arranging a plurality of the first holes 91 along the virtual circle C1, the motor 6 can be firmly fixed to the flange 9 in a well-balanced manner. Similarly, by arranging a plurality of the second holes 92 along the virtual circle C2, the harmonic gear device 7 can be firmly fixed to the flange 9 in a well-balanced manner. Therefore, the mechanical strength of the robot joint mechanism 51 is improved, and a decrease in the lifespan of the robot joint mechanism 51 can be suppressed. Further, by arranging a plurality of the third holes 93 along the virtual circle C3, the robot joint mechanism 51 can be firmly fixed to the base 2 in a well-balanced manner, so that the mechanical strength of the robot 1 is improved.

[0028] The three concentric virtual circles C1, C2, and C3 have a relationship of radius r1 < radius r2 < radius r3. That is, the second hole 92 is located closer to the central axis A1 side than the third hole 93, and the first hole 91 is located closer to the central axis A1 side than the second hole 92. Thus, by arranging the first hole 91 closer to the central axis A1 side than the second hole 92, the motor 6 with a smaller size than the harmonic gear device 7 can be more reliably fixed to the flange 9 without using an intermediate member.

[0029] ≪Motor 6≫ As shown in FIG. 2, the motor 6 is arranged below the flange 9. Further, the motor 6 is, for example, an AC servo motor. However, the motor 6 is not particularly limited, and for example, a DC servo motor, a stepping motor, or the like may be used. Such a motor 6 has a shaft 61 that is an output shaft, a stator (not shown) that rotates the shaft 61, and a housing 63 that houses these components.

[0030] At the upper end of the housing 63, four insertion holes 64 are formed for screwing the motor 6 to the flange 9. Each insertion hole 64 overlaps with the first hole 91, and a first bolt B1 is inserted into each insertion hole 64 from below, and the first bolt B1 is screwed and inserted into the first hole 91 of the flange 9. Thus, the motor 6 is fixed to the flange 9. However, the number of the first holes 91 and the corresponding insertion holes 64 is not particularly limited. Also, the number of the first holes 91 and the insertion holes 64 does not have to be the same.

[0031] Here, in the state where the motor 6 is fixed to the flange 9, as shown in FIG. 4, at least one, eight second holes 92 in the illustrated configuration overlap with the motor 6. Even in such a configuration, according to the assembly method described later, the robot joint mechanism 51 can be assembled. Therefore, it is not necessary to consider the overlap between the second hole 92 and the motor 6, and the design freedom of the robot joint mechanism 51 is increased. As a result, the robot joint mechanism 51 to which motors 6 of various sizes can be applied is obtained, and its versatility is increased.

[0032] Also, as shown in FIG. 2, the shaft 61 is supported by the housing 63 so as to be rotatable about the central axis A1. Further, the shaft 61 is connected to the harmonic gear device 7 at its upper end and is connected to the encoder 8 at its lower end. Thereby, the rotation of the shaft 61 is transmitted to the harmonic gear device 7 and the encoder 8, respectively.

[0033] Also, the housing 63 is provided with a convex portion on the upper side, and the convex portion of the housing 63 engages with the side wall of the through hole 90 of the flange 9. An oil seal 67 is disposed between the housing 63 and the flange 9, and an oil seal 65 is disposed in the gap between the shaft 61 and the housing 63. Oil leakage of the harmonic gear device 7 is suppressed by these oil seals 65 and 67.

[0034] ≪Encoder 8≫ As shown in FIG. 2, the encoder 8 is arranged side by side with the motor 6 along the first rotation axis J1 and is located below the motor 6. The encoder 8 includes an optical scale 81 fixed to the shaft 61 and an optical sensor 82 that detects the rotational state of the optical scale 81.

[0035] The optical scale 81 rotates around the first rotation axis J1 together with the shaft 61. In addition, a detection pattern (not shown) capable of detecting the rotation angle of the optical scale 81 is formed on the lower surface of the optical scale 81. On the other hand, the optical sensor 82 includes a light emitting element that emits light toward the detection pattern on the optical scale 81 and a light receiving element that receives the light reflected by the detection pattern. In the encoder 8 having such a configuration, the waveform of the output signal from the light receiving element changes as the optical scale 81 rotates around the first rotation axis J1. Therefore, the rotation angle of the shaft 61 can be detected based on this output signal.

[0036] ≪Harmonic Gear Unit 7≫ As shown in FIG. 2, the harmonic gear unit 7 is arranged on the upper surface side of the flange 9. The harmonic gear unit 7 is arranged side by side with the motor 6 along the first rotation axis J1 and is located above the motor 6. Such a harmonic gear unit 7 decelerates and outputs the rotation of the shaft 61 at a high reduction ratio and generates a high torque proportional to the reduction ratio.

[0037] The harmonic gear unit 7 includes a wave generator 71, a flex spline 73, a circular spline 76, and a cover member 79. In the harmonic gear unit 7, the wave generator 71 is the input side to which the power of the motor 6 is input, and the circular spline 76 is the output side that decelerates and outputs the power of the motor 6.

[0038] Further, the circular spline 76 is an annular internal gear composed of a rigid body that does not substantially bend. The circular spline 76 has an inner bearing 761 and an outer bearing 762 located outside the inner bearing 761. Also, the inner bearing 761 and the outer bearing 762 are connected by a bearing 763, and the outer bearing 762 and the inner bearing 761 are relatively rotatable.

[0039] Also, an internal tooth 761b that meshes with the flex spline 73 is formed on the inner peripheral portion of the inner bearing 761. Further, 16 screw holes 761a are formed on the lower surface of the inner bearing 761. Each screw hole 761a overlaps with the second hole 92, and a second bolt B2 is inserted into each second hole 92 from below, and the second bolt B2 is screwed and inserted into the screw hole 761a. Thereby, the harmonic gear device 7 is fixed to the flange 9. However, the number of the second holes 92 and the corresponding screw holes 761a is not particularly limited. Also, the number of the second holes 92 and the screw holes 761a does not have to be the same.

[0040] As described above, both the motor 6 and the harmonic gear device 7 are fixed to the flange 9 by the first bolt B1 and the second bolt B2 inserted from below. In this way, by inserting the first and second bolts B1, B2 from the same side, the assembly and disassembly of the robot joint mechanism 51 are facilitated. However, it is not limited to this, and the first and second bolts B1, B2 may be inserted from different sides from each other.

[0041] On the other hand, an insertion hole 762a that penetrates the upper and lower surfaces is formed in the outer bearing 762. Then, a fourth bolt B4 is inserted into each insertion hole 762a from below, and the fourth bolt B4 is screwed and inserted into the cover member 79. Thereby, the outer bearing 762 and the cover member 79 are fixed. Further, the cover member 79 is fixed to the first arm 31 as the second member by a fifth bolt B5. However, the fixing method of the outer bearing 762 and the first arm 31 is not particularly limited. For example, the cover member 79 may be omitted and directly fixed to the first arm 31.

[0042] Also, the flex spline 73 is disposed inside the circular spline 76. The flex spline 73 has a cylindrical portion 731 having flexibility to be bent along the outer periphery of the wave generator 71, and an annular flange portion 732 connected to the upper end portion of the cylindrical portion 731.

[0043] External teeth 731a that mesh with the internal teeth 761b of the circular spline 76 are formed on the outer peripheral portion of the cylindrical portion 731. The number of teeth of the external teeth 731a is set to be less than the number of teeth of the internal teeth 761b. The flange portion 732 is fixed to the cover member 79 together with the outer bearing 762 by the fourth bolt B4.

[0044] Also, the wave generator 71 is fixed to the shaft 61 and has a wave generating portion 711 that rotates in conjunction with the rotation of the shaft 61, and a bearing 712 fitted between the wave generating portion 711 and the flex spline 73. The outer periphery of the wave generating portion 711 is elliptical or oval in a plan view from the direction along the central axis A1. That is, the wave generator 71 has a shape having a longitudinal direction and a short direction orthogonal thereto. The wave generator 71 contacts the inner peripheral surface of the cylindrical portion 731 of the flex spline 73, bends the cylindrical portion 731 into an elliptical or oval shape, and partially meshes the external teeth 731a of the cylindrical portion 731 with the internal teeth 761b of the circular spline 76. Thereby, the teeth mesh with the circular spline 76 at the major axis portion, and the teeth are completely separated at the minor axis portion. Note that the length of the major axis of the wave generator 71 is the major diameter R 71 as described above, the major diameter R 71 is larger than the diameter R 90 of the through hole 90.

[0045] When the driving force from the motor 6 is input to the wave generator 71, the flexspline 73 and the circular spline 76 rotate relative to each other around the central axis A1 due to the difference in the number of teeth while their meshing positions move sequentially in the circumferential direction. In the present embodiment, since the flexspline 73 and the outer spindle bearing 762 are fixed to the first arm 31 via the cover member 79, and the inner spindle bearing 761 is fixed to the base 2 via the flange 9, the first arm 31 rotates around the first rotation axis J1 with respect to the base 2.

[0046] According to such a harmonic gear device 7, the rotation input from the motor 6 to the wave generator 71 is decelerated and output from the outer spindle bearing of the circular spline 76, and torque proportional to the reduction ratio can be obtained on the output side.

[0047] Above, the configuration of the robot joint mechanism 51 has been described. As described above, the robot joint mechanism 51 has the relationship of R 90 <R 71 By having such a relationship, a space is created inside the second hole 92 of the flange 9, and the first hole 91 can be formed in this space. That is, the first hole 91 for fixing the motor 6 can be arranged inside the second hole 92 for fixing the harmonic gear device 7. Therefore, even a motor 6 having a smaller size (diameter) than the harmonic gear device 7 can be fixed to the flange 9 without passing through a relay member. For reference, in FIG. 5, R 90 >R 71 is shown, and a configuration in which the motor 6 is fixed to the flange 9 via the relay member 10 is illustrated as a robot joint mechanism 51'.

[0048] Therefore, the mounting accuracy of the motor 6 to the flange 9 is improved, and the deviation between the rotation axis of the shaft 61 and the rotation axis of the harmonic gear device 7 can be effectively suppressed. As a result, the driving of the robot joint mechanism 51 becomes stable, and it is difficult for the robot joint mechanism 51 to be subjected to excessive stress unintentionally. As a result, the reduction in the life of the robot joint mechanism 51 can be effectively suppressed. On the other hand, since there is no relay member, the number of components is reduced, the tolerances of the flange 9 and the housing 63 can be set more generously, the decrease in the yield rate can be suppressed, and the manufacturing cost can be reduced.

[0049] Next, an assembling method of the robot joint mechanism 51 will be described. As shown in FIG. 6, the assembling method of the robot joint mechanism 51 includes a preparation step S1 of preparing a flange 9, an insertion step S2 of inserting the shaft 61 of the motor 6 into the through hole 90 of the flange 9, a temporary fixing step S3 of temporarily fixing the motor 6 to the flange 9, a connection step S4 of connecting a wave generator 71 to the shaft 61, an arrangement step S5 of arranging a flex spline 73 and a circular spline 76, a release step S6 of removing the temporary fixing of the motor 6, a first fixing step S7 of fixing the harmonic gear device 7 to the flange 9, and a second fixing step S8 of fixing the motor 6 to the flange 9. Hereinafter, each of these steps S1 to S8 will be described in order.

[0050] << Preparation Step S1 >> First, as shown in FIG. 7, a flange 9 is prepared. The flange 9 is formed with a through hole 90, a first hole 91, a second hole 92, and a third hole 93.

[0051] << Insertion Step S2 >> Next, as shown in FIG. 8, the motor 6 is prepared, and the shaft 61 of the motor 6 is inserted into the through hole 90 of the flange 9 from the lower side. As a result, the shaft 61 protrudes upward from the through hole 90.

[0052] << Temporary Fixing Step S3 >> Next, as shown in FIG. 9, the motor 6 is temporarily fixed to the flange 9 using the first bolt B1. In this step, the first bolt B1 is tightened with a fastening force such that the motor 6 does not rattle against the flange 9. By eliminating the rattling between the motor 6 and the flange 9, the subsequent connection step S4 and arrangement step S5 can be performed smoothly and accurately.

[0053] <<Connection Step S4>> Next, as shown in FIG. 10, the wave generator 71 is connected to and fixed to the shaft 61 from the upper surface side of the flange 9. In this way, after inserting the shaft 61 into the through hole 90, by connecting the wave generator 71 to the shaft 61 from the opposite side, the major axis R 71 Even with a through hole 90 having a diameter smaller than that of, the robot joint mechanism 51 can be easily assembled.

[0054] <<Arrangement Step S5>> Next, as shown in FIG. 11, the flex spline 73 and the circular spline 76 are arranged from the upper surface side of the flange 9, and the harmonic gear device 7 is assembled.

[0055] <<Release Step S6>> Next, as shown in FIG. 12, the first bolt B1 that fixes the motor 6 to the flange 9 is removed to release the temporary fixing of the motor 6. Even when the temporary fixing is released, since the shaft 61 is supported by the harmonic gear device 7, the detachment of the motor 6 is prevented. Also, in the state where the temporary fixing is released, the housing 63 becomes rotatable about the central axis A1. Thereby, the first fixing step S7 can be suitably performed.

[0056] <<First Fixing Step S7>> Next, as shown in FIG. 13, the second bolts B2 are inserted through the respective second holes 92 and screwed into the screw holes 761a of the inner main bearing 761. Thereby, the harmonic gear device 7 is fixed to the flange 9.

[0057] Specifically, first, the housing 63 is rotated around the central axis A1 with respect to the flange 9 to the state shown in FIG. 14. In FIG. 14, eight second holes 92 overlap with the housing 63, and the remaining eight housings 63 do not overlap with the housing 63. Next, as shown in FIG. 15, a second bolt B2 is inserted through each second hole 92 that does not overlap with the housing 63 and is screwed and inserted into the screw hole 761a of the inner main bearing 761.

[0058] Next, as shown in FIG. 16, the housing 63 is rotated 45° around the central axis A1 with respect to the flange 9. In this state, the second holes 92 that overlapped with the housing 63 in the state of FIG. 14 do not overlap with the housing 63. On the contrary, the second holes 92 that did not overlap with the housing 63 in the state of FIG. 14 overlap with the housing 63. Next, as shown in FIG. 17, a second bolt B2 is inserted through each second hole 92 that does not overlap with the housing 63 and is screwed and inserted into the screw hole 761a of the inner main bearing 761.

[0059] As a result, the second bolts B2 are inserted through all the second holes 92, and the harmonic gear device 7 is fixed to the flange 9. That is, the harmonic gear device 7 is screwed to the flange 9 using the second holes 92 that overlap with the motor 6. Thereby, the harmonic gear device 7 can be firmly and evenly fixed to the flange 9 around the through hole 90. Therefore, the mechanical strength of the robot joint mechanism 51 is improved, and a decrease in the life of the robot joint mechanism 51 can be suppressed. Further, according to such a method, since it is only necessary to rotate the housing 63 so that all the second holes 92 do not overlap with the housing 63 in order, the need to consider the overlap between the second holes 92 and the motor 6 is reduced, and the degree of freedom in designing the robot joint mechanism 51 is increased. As a result, the robot joint mechanism 51 can accommodate motors 6 of various sizes, and its versatility is enhanced.

[0060] ≪Second Fixing Step S8≫ Next, as shown in FIG. 18, insert the first bolt B1 into each insertion hole 64 of the housing 63 from below, and threadedly insert the first bolt B1 into the first hole 91 of the flange 9 to fix the motor 6 to the flange 9.

[0061] Thus, the assembly of the robot joint mechanism 51 is completed. According to such an assembly method, even a motor 6 that is smaller in size (diameter) than the harmonic gear device 7 can be fixed to the flange 9 without passing through a relay member. Therefore, the mounting accuracy of the motor 6 to the flange 9 is improved, and the deviation between the rotation axis of the shaft 61 and the rotation axis of the harmonic gear device 7 can be effectively suppressed. As a result, the drive of the robot joint mechanism 51 is stabilized, and it becomes difficult for excessive stress that is not intended to be applied to the robot joint mechanism 51. As a result, a decrease in the life of the robot joint mechanism 51 can be effectively suppressed. On the other hand, since there is no relay member, the number of components is reduced, the tolerances of the flange 9 and the housing 63 can be set more generously, a decrease in the yield rate can be suppressed, and this also leads to a decrease in the manufacturing cost.

[0062] Also, it is not limited to the order of each of the steps S1 to S8 in the above assembly method, and other orders may be used. For example, the order after the placement step S5 may be changed, and a part of the first fixing step S7 may be executed before the release step S6. That is, the second bolt B2 may be inserted into the eight second holes 92 that do not overlap with the housing 63 and threadedly inserted into the screw hole 761a of the inner main bearing 761. By doing so, the flange 9 and the harmonic gear device 7 can be stabilized and assembled.

[0063] The above describes the assembly method of the robot 1, the robot joint mechanism 51, and the robot joint mechanism 52. As described above, the robot joint mechanism 51 includes a flange 9 as a robot component including a through hole 90, a first hole 91 and a second hole 92 disposed around the through hole 90, a motor 6 screwed using the first hole 91 and having a shaft 61 as an output shaft inserted through the through hole 90, and a harmonic gear device 7 screwed using the second hole 92 and including a wave generator 71 connected to the shaft 61. The diameter R of the through hole 90 90 is smaller than the major diameter R of the wave generator 71 71 .

[0064] Thus, due to the relationship of R 90 < R 71 , a space is generated inside the second hole 92 of the flange 9, and the first hole 91 can be formed in this space. That is, the first hole 91 for fixing the motor 6 can be disposed inside the second hole 92 for fixing the harmonic gear device 7. Therefore, even a motor 6 having a size (diameter) smaller than that of the harmonic gear device 7 can be fixed to the flange 9 without passing through the relay member 10 as shown in FIG. 5. Therefore, the mounting accuracy of the motor 6 to the flange 9 is improved, and the deviation between the rotation axis of the shaft 61 and the rotation axis of the harmonic gear device 7 can be effectively suppressed. Therefore, the drive of the robot joint mechanism 51 is stabilized, and it is difficult for excessive stress unintended for the robot joint mechanism 51 to be applied. As a result, a decrease in the life of the robot joint mechanism 51 can be effectively suppressed. On the other hand, since the relay member 10 is not used, the number of members is reduced, the tolerances of the flange 9 and the housing 63 can be set more loosely, and a decrease in the yield rate can be suppressed, leading to a decrease in the manufacturing cost.

[0065] Also, as described above, the motor 6 and the harmonic gear device 7 are screwed to the flange 9 from the same side. This facilitates the assembly and disassembly of the robot joint mechanism 51.

[0066] Also, as described above, a plurality of second holes 92 are arranged along the periphery of the through hole 90. Thereby, the harmonic gear device 7 can be firmly and evenly fixed to the flange 9 around the through hole 90. Therefore, the mechanical strength of the robot joint mechanism 51 can be improved, and a decrease in the life of the robot joint mechanism 51 can be suppressed.

[0067] Also, as described above, in a plan view from the direction along the central axis A1 of the shaft 61, at least one second hole 92 overlaps with the motor 6, and the harmonic gear device 7 is screwed to the flange 9 using the second hole 92 that overlaps with the motor 6. Thereby, the harmonic gear device 7 can be firmly and evenly fixed to the flange 9 around the through hole 90. Therefore, the mechanical strength of the robot joint mechanism 51 can be improved, and a decrease in the life of the robot joint mechanism 51 can be suppressed.

[0068] Also, as described above, the first hole 91 is located closer to the through hole side than the second hole 92. Thereby, the motor 6 having a smaller size than the harmonic gear device 7 can be more reliably fixed to the flange 9 without passing through the relay member 10.

[0069] Also, as described above, the robot 1 includes a base 2 as a first member, a first arm 31 as a second member, and a robot joint mechanism 51 that connects the base 2 and the first arm 31 and rotates the first arm 31 with respect to the base 2. The robot joint mechanism 51 includes a through hole 90, a flange 9 as a robot component provided with a first hole 91 and a second hole 92 arranged around the through hole 90, a motor 6 that is screwed using the first hole 91 and has an output shaft, the shaft 61, inserted through the through hole 90, and a harmonic gear device 7 that is screwed using the second hole 92 and includes a wave generator 71 connected to the shaft 61. The diameter R of the through hole 90 90 is smaller than the major axis R of the wave generator 71. 71 Thereby, the effects of the robot joint mechanism 51 described above can be enjoyed, and the robot 1 having excellent reliability can be obtained.

[0070] Also, as described above, the robot component may be the base 2. That is, by fixing the motor 6 and the harmonic gear device 7 to the base 2 without passing through the flange 9, the number of parts can be reduced. And since the number of parts is reduced, the fastening of screws is eliminated, and the rigidity can be improved. Also, the man-hour for assembly can be reduced.

[0071] Also, as described above, the assembling method of the robot joint mechanism 51 includes a preparation step S1 of preparing a flange 9 as a robot component having a through hole 90 and a first hole and a second hole arranged around the through hole 90, an insertion step S2 of inserting a shaft 61, which is an output shaft of the motor 6, into the through hole 90 from one side, i.e., the lower side, of the flange 9, and from the other side, i.e., the upper side, of the flange 9, a connection step S4 of connecting a wave generator 71, which is a part of the harmonic gear device 7 and has a major diameter R 71 is larger than the diameter R of the through hole 90 90 to the shaft 61, an arrangement step S5 of arranging a flex spline 73 and a circular spline 76, which are parts of the harmonic gear device 7, from the upper side of the flange 9, a first fixing step S7 of screwing the harmonic gear device 7 to the flange 9 using the second hole 92 from the lower side of the flange 9, and a second fixing step S8 of screwing the motor 6 to the flange 9 using the first hole 91 from the lower surface side of the flange 9.

[0072] Thus, R 90 < R 71By having the relationship, a space is created inside the second hole 92 of the flange 9, and the first hole 91 can be formed in this space. That is, the first hole 91 for fixing the motor 6 can be arranged inside the second hole 92 for fixing the harmonic gear device 7. Therefore, even a motor 6 that is smaller in size (diameter) than the harmonic gear device 7 can be fixed to the flange 9 without passing through the relay member 10 as shown in FIG. 5. For this reason, the mounting accuracy of the motor 6 to the flange 9 is improved, and the deviation between the rotation axis of the shaft 61 and the rotation axis of the harmonic gear device 7 can be effectively suppressed. Accordingly, the driving of the robot joint mechanism 51 becomes stable, and it becomes difficult for an excessive stress unintended for the robot joint mechanism 51 to be applied. As a result, a decrease in the life of the robot joint mechanism 51 can be effectively suppressed. On the other hand, since the relay member 10 is not used, the number of members is reduced, the tolerances of the flange 9 and the housing 63 can be set more loosely, a decrease in the yield rate is suppressed, and the manufacturing cost is also reduced.

[0073] Also, as described above, the assembling method of the robot joint mechanism 51 is performed between the insertion step S2 and the connection step S4, and includes a temporary fixing step S3 for temporarily fixing the motor 6 to the flange 9, and a release step S6 for releasing the temporary fixing of the motor 6, which is performed between the arrangement step S5 and the first fixing step S7. Thereby, each step after the temporary fixing step S3 can be suitably performed.

[0074] Also, as described above, a plurality of second holes 92 are formed along the periphery of the through hole 90. In the state where the arrangement step S5 is completed, at least one second hole 92 overlaps with the motor 6 in a plan view from the direction along the central axis A1 of the shaft 61. In the first fixing step S7, the motor 6 is rotated around the central axis A1 to eliminate the overlap with the motor 6, and the harmonic gear device 7 is screwed to the flange 9 using all the second holes 92. Thereby, the harmonic gear device 7 can be firmly fixed to the flange 9 in a well-balanced manner around the through hole 90. Therefore, the mechanical strength of the robot joint mechanism 51 can be improved, and a decrease in the life of the robot joint mechanism 51 can be suppressed.

[0075] <Second Embodiment> FIG. 19 is a cross-sectional view of a robot joint mechanism according to the second embodiment.

[0076] In the robot joint mechanism 51 of the present embodiment, it is the same as the robot joint mechanism 51 of the first embodiment described above except that the arrangement of the oil seal 65 is different. Therefore, in the following description, regarding the present embodiment, the differences from the first embodiment described above will be mainly described, and the description of the same matters will be omitted. Also, in each figure of the present embodiment, the same components as those in the above-described embodiment are denoted by the same reference numerals.

[0077] As shown in FIG. 19, in the robot joint mechanism 51 of the present embodiment, the diameter R of the through hole 90 is smaller than that in the first embodiment described above 90 and its inner surface is close to the outer peripheral surface of the shaft 61. And the oil seal 65 for suppressing oil leakage of the harmonic gear device 7 was arranged in the gap between the housing 63 and the shaft 61 in the first embodiment described above, but in the present embodiment, it is arranged between the inner peripheral surface of the through hole 90 and the outer peripheral surface of the shaft 61. According to such a configuration, for example, the oil seal 67 can be omitted, and the configuration of the robot joint mechanism 51 becomes simpler. Also, the number of parts is reduced, and the manufacturing cost can be reduced.

[0078] As described above, the robot joint mechanism 51 of this embodiment has an oil seal 65 disposed between the inner peripheral surface of the through hole 90 and the outer peripheral surface of the shaft 61. As a result, the configuration of the robot joint mechanism 51 becomes simpler. In addition, the number of components is reduced, and the manufacturing cost can be reduced.

[0079] Also, the second embodiment as described above can exhibit the same effects as those of the first embodiment described above.

[0080] As described above, the robot joint mechanism, the robot, and the assembling method of the robot joint mechanism of the present invention have been described based on the illustrated embodiments. 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, any other arbitrary components may be added to the present invention.

Explanation of reference numerals

[0081] 1…Robot, 10…Relay member, 2…Base, 3…Arm, 31…First arm, 32…Second arm, 33…Working head, 331…Spline nut, 332…Ball screw nut, 333…Spline shaft, 34…End effector, 4…Robot control device, 51…Robot joint mechanism, 51’…Robot joint mechanism, 52…Robot joint mechanism, 53…Drive device, 54…Drive device, 6…Motor, 61…Shaft, 63…Housing, 64…Insertion hole, 65…Oil seal, 67…Oil seal, 7…Harmonic gear device, 71…Wave generator, 711…Wave generating part, 712…Bearing, 73…Flexspline, 731…Cylindrical part, 731a…External teeth, 732…Flange part, 76…Circular spline, 761…Inner main bearing, 761a…Thread hole, 761b…Inner teeth, 762…Outer main bearing, 762a…Insertion hole, 763…Bearing, 79…Cover member, 8…Encoder, 81…Optical scale, 82…Optical sensor, 9…Flange, 90…Through hole, 91…First hole, 92…Second hole, 93…Third hole, A1…Central axis, B1…First bolt, B2…Second bolt, B3…Third bolt, B4…Fourth bolt, B5…Fifth bolt, C1…Virtual circle, C2…Virtual circle, C3…Virtual circle, J1…First rotation axis, J2…Second rotation axis, J3…Third rotation axis, R 71 …Major axis, R 90 …Diameter, r1…Radius, r2…Radius, r3…Radius, S1…Preparation step, S2…Insertion step, S3…Temporary fixing step, S4…Connection step, S5…Arrangement step, S6…Release step, S7…First fixing step, S8…Second fixing step

Claims

1. A robot component including a through hole, a first hole and a second hole disposed around the through hole; A motor including a housing and an output shaft rotatably supported by the housing, the output shaft being inserted through the through hole; A wave gear device including a wave generator connected to the output shaft and having an elliptical outer periphery in a plan view from a direction along the output shaft, a flex spline that is elastically deformed along the outer periphery of the wave generator and has external teeth, and a circular spline that has internal teeth meshing with the external teeth and rotates relative to the flex spline; The circular spline is screwed to the robot component using the second hole; The motor is screwed to the robot component using the first hole; The diameter of the through hole is smaller than the major axis of the wave generator; The housing engages with the side wall of the through hole; A robot joint mechanism, wherein the circular spline engages with a stepped portion provided on the robot component.

2. The robot joint mechanism according to claim 1, wherein the motor and the wave gear device are screwed to the robot component from the same side.

3. The robot joint mechanism according to claim 1 or 2, wherein a plurality of the second holes are arranged along the periphery of the through hole.

4. In a plan view from a direction along the central axis of the output shaft, At least one of the second holes overlaps with the motor; The robot joint mechanism according to claim 3, wherein the wave gear device is screwed to the robot component using the second hole that overlaps with the motor.

5. The robot joint mechanism according to any one of claims 1 to 4, further including an oil seal disposed between the inner peripheral surface of the through hole and the outer peripheral surface of the output shaft.

6. The robot joint mechanism according to any one of claims 1 to 5, wherein the first hole is located closer to the through hole than the second hole.

7. A first member; A second member; A robot joint mechanism connecting the first member and the second member and rotating the second member relative to the first member; The robot joint mechanism includes: A robot component including a through hole, a first hole and a second hole disposed around the through hole; A motor comprising a housing and an output shaft rotatably supported by the housing, wherein the output shaft is inserted into the through hole. A wave gear device including a wave generator connected to the output shaft and having an elliptical outer periphery in a plan view from a direction along the output shaft, a flex spline that flexes and deforms along the outer periphery of the wave generator and has external teeth, and a circular spline that has internal teeth meshing with the external teeth and rotates relative to the flex spline. The circular spline is screwed to the robot component using the second hole. The motor is screwed to the robot component using the first hole. The diameter of the through hole is smaller than the major axis of the wave generator. The housing engages with the side wall of the through hole. A robot, characterized in that the circular spline engages with a stepped portion provided on the robot component.

8. The robot component is the first member, and the robot according to claim 7.

9. A preparation step of preparing a robot component including a through hole and a first hole and a second hole disposed around the through hole. An insertion step of inserting the output shaft of the motor into the through hole from one side of the robot component. A temporary fixing step of temporarily fixing the motor to the robot component. A connection step of connecting a wave generator, which is a part of the wave gear device and has a major axis larger than the diameter of the through hole, to the output shaft from the other side of the robot component. An arrangement step of arranging a flex spline and a circular spline, which are parts of the wave gear device, from the other side of the robot component. A release step of releasing the temporary fixing of the motor. A first fixing step of screwing the wave gear device to the robot component using the second hole from one side of the robot component. A second fixing step of screwing the motor to the robot component using the first hole from one side of the robot component, and an assembling method of a robot joint mechanism characterized by including the above steps.

10. A preparation step of preparing a robot component including a through hole and a first hole and a second hole disposed around the through hole. An insertion step of inserting the output shaft of the motor through the through hole from one side of the robot component part; A connection step of connecting a wave generator, which is a part of the harmonic gear device and has a major diameter larger than the diameter of the through hole, to the output shaft from the other side of the robot component part; An arrangement step of arranging a flex spline and a circular spline, which are parts of the harmonic gear device, from the other side of the robot component part; A first fixing step of screwing the harmonic gear device to the robot component part using the second hole from one side of the robot component part; A second fixing step of screwing the motor to the robot component part using the first hole from one side of the robot component part, and includes: A plurality of the second holes are formed along the periphery of the through hole; In a state where the arrangement step is completed, at least one of the second holes overlaps with the motor in a plan view from a direction along the central axis of the output shaft; In the first fixing step, the harmonic gear device is screwed to the robot component part using all the second holes while rotating the motor around the central axis to eliminate the overlap with the motor. A method for assembling a robot joint mechanism, characterized by this.

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