Robotic machining center, robotic arm, and machining method using robotic machining center

Abstract

To improve machining accuracy when using articulated robots. [Solution] The robotic machining center 10 is a multi-joint robotic arm 11 having a plurality of joints J1 to J6 and a braking mechanism 16 that can brake the rotation of at least one of the plurality of joints J1 to J6 when the servo is on, an end effector 55 positioned at the tip of the robotic arm 11 which is capable of mounting a tool 72 and has a rotatable spindle 71, and a feed table 69 that feeds out the spindle 71.

Description

Technical Field

[0001] The present invention relates to a robot processing machine, a robot arm, and a processing method using the robot processing machine.

Background Art

[0002] An assembly attached to an end flange of an articulated robot is known (Japanese Unexamined Patent Application Publication No. 2024-504278). The assembly is attached to the end flange of the articulated robot. The assembly includes a parallel robot and a servo spindle.

Summary of Invention

Problems to be Solved by the Invention

[0003] When processing using an articulated robot, the tip of the robot arm may shake due to processing reaction force, leading to a reduction in processing accuracy. The present invention aims to improve processing accuracy when performing processing using an articulated robot.

Means for Solving the Problems

[0004] A first aspect of the present invention is: An articulated robot arm, a plurality of joints, and a braking mechanism capable of braking rotation of at least one of the plurality of joints while servo is on, the robot arm having the above structure; an end effector disposed at the tip of the robot arm, the end effector being capable of mounting a tool and having a rotatable spindle; and a feed carriage that feeds out the spindle, the robot processing machine having the above components.

[0005] A second aspect of the present invention is: An articulated robot arm having a braking mechanism that respectively brakes between two links connected to each of a plurality of joints.

[0006] A third aspect of the present invention is, A machining method using a multi-joint robot arm having an end effector, The robot arm stops the position of the end effector, The joints of the robot arm are braked, The end effector rotates the spindle, and the feed table moves the spindle to process the workpiece. After the processing is complete, the braking of the joint of the robot arm is released. This is a processing method.

[0007] Machining processes include, for example, cutting, grinding, and rolling. Cutting processes include, for example, drilling, tapping, milling, end milling, and chamfering. Grinding processes include, for example, grinding cuts and drilling using grinding wheels. Workpieces include, for example, metals, fiber-reinforced plastics, and laminates. Fiber-reinforced plastics include, for example, carbon fiber reinforced plastics and glass fiber reinforced plastics. Laminates are, for example, materials in which metals or fiber-reinforced plastics are laminated.

[0008] A robotic arm may have, for example, four to six axes. Preferably, the braking mechanism is placed at each joint. The braking mechanism may be placed only at joints that are prone to rotation during machining. The braking mechanism may be placed only at the end joint of the robot arm (the 6th axis in the case of a 6-axis serial link robot). The braking mechanism may be placed only at the end joint of the robot arm (the 6th axis) and the joint just before it (the 5th axis). Preferably, the electromagnetic brake is of the excitation type.

[0009] A robotic arm may have a kinetic meter that directly measures the angular velocity between two links that straddle a joint. The kinetic meter may be, for example, a rotary encoder or a resolver.

[0010] Preferably, when machining using a robotic machining center, all joints of the robotic arm are braked. Alternatively, only the joints of the robotic arm that are easily rotated may be braked.

[0011] The feed table may be located on the end effector. Examples of feed tables include the ram, headstock, and slide table (X-slider). The feed table may be movable in the direction of the spindle axis. The feed table may also be movable in a direction perpendicular to the direction of the spindle axis. The ram is fed in the direction of the spindle. The headstock may be fed in a direction perpendicular to the direction of the spindle (X direction).

[0012] The feed platform may be placed on the frame. The frame may be placed on the floor. The robot arm may be placed on the arm platform (feed platform). In this case, the spindle is fed together with the robot arm.

[0013] The end effector may have a slide unit. The slide unit may have an X-axis guide extending perpendicular to the spindle. It may also have an X-slider that reciprocates along the X-axis guide.

[0014] The end effector may have a single-axis machining unit. The single-axis machining unit may have a Z-axis guide and a ram that is fed along the Z-axis guide. The single-axis machining unit may have a body. The body supports the Z-axis guide and the ram. The single-axis machining unit may be positioned on an X-slider. In this case, the X-slider and the body may be a single unit. Furthermore, the end effector may consist solely of a single-axis machining unit.

[0015] The end effector may have a spindle head. The spindle head is located in a slide unit and is fed in the X-axis direction. The spindle head supports the spindle. The slide unit feeds the spindle in the X direction. [Effects of the Invention]

[0016] According to the robot processing machine, the robot arm, and the processing method of the present invention, machining accuracy can be improved when performing machining using an articulated robot. [Brief Description of the Drawings]

[0017] [Figure 1] Robot processing machine of Embodiment 1 [Figure 2] Cross-sectional view taken along line II-II of Figure 1 [Figure 3] Enlarged view of part III in Figure 1 [Figure 4] Processing method of Embodiment 1 [Figure 5] Robot processing machine of Embodiment 2 [Figure 6] End effector of Embodiment 3 [Figure 7] Robot processing machine of Embodiment 4 [Mode for Carrying Out the Invention]

[0018] <First Embodiment> As shown in Figure 1, the robot processing machine 10 of the present embodiment includes a robot arm 11 and an end effector 55.

[0019] The robot arm 11 is a 6-axis vertical articulated robot arm. The robot arm 11 has first to sixth axes (first to sixth joints) J1, J2, J3, J4, J5, J6. The robot arm 11 has a base 13 and first to sixth links 15, 21, 29, 35, 41, 47. The robot arm 11 includes first to sixth motors 17, 23, 31, 37, 43, 49, first to sixth speed reducers 18, 24, 32, 38, 44, 50, first to sixth brakes (braking mechanisms) 16, 22, 30, 36, 42, 48, and first to sixth encoders 20, 26, 34, 40, 46, 52.

[0020] The first link 15 is disposed on the base 13 and rotates around the first axis J1. The second link 21 is disposed on the first link 15 and rotates around the second axis J2. The third link 29 is positioned on the second link 21 and rotates around the third axis J3. The fourth link 35 is positioned at the third link 29 and rotates around the fourth axis J4. The fifth link 41 is positioned at the fourth link 35 and rotates around the fifth axis J5. The sixth link 47 is positioned on the fifth link 41 and rotates around the sixth axis J6. The sixth link 47 has a mounting flange 47a at its tip.

[0021] The first to sixth motors 17, 23, 31, 37, 43, and 49 are each positioned near the first to sixth axes J1 to J6. The first to sixth motors 17, 23, 31, 37, 43, and 49 are each connected to the first to sixth gearboxes 18, 24, 32, 38, 44, and 50, respectively. The first motor 17 rotates the first link 15 relative to the base 13 around the first axis J1. The second motor 23 rotates the second link 21 relative to the first link 15 around the second axis J2. The third motor 31 rotates the third link 29 relative to the second link 21 around the third axis J3. The fourth motor 37 rotates the fourth link 35 relative to the third link 29 around the fourth axis J4. The fifth motor 43 rotates the fifth link 41 relative to the fourth link 35 around the fifth axis J5. The sixth motor 49 rotates the sixth link 47 relative to the fifth link 41 around the sixth axis J6.

[0022] The first brake 16 is positioned between the base 13 and the first link 15. The first brake 16 directly brakes the rotation of the first link 15 relative to the base 13. The second brake 22 is positioned between the first link 15 and the second link 21. The second brake 22 directly brakes the rotation of the second link 21 relative to the first link 15. The third brake 30 is positioned between the second link 21 and the third link 29. The third brake 30 directly brakes the rotation of the second link 21 and the third link 29. The third brake 30 directly brakes the rotation of the second link 21 and the third link 29. The fourth brake 36 is positioned between the third link 29 and the fourth link 35. The fourth brake 36 directly brakes the rotation of the third link 29 and the fourth link 35. The fifth brake 42 is positioned between the fourth link 35 and the fifth link 41. The fifth brake 42 directly brakes the rotation of the fourth link 35 and the fifth link 41. The sixth brake 48 is positioned between the fifth link 41 and the sixth link 47. The sixth brake 48 directly brakes the rotation of the fifth link 41 and the sixth link 47.

[0023] Encoders 20, 26, 34, 40, 46, and 52, respectively, directly measure the rotational speed of axes J1 to J6.

[0024] As shown in Figures 1 and 2, the end effector 55 has a slide unit 56 and a single-axis machining unit 63.

[0025] The slide unit 56 includes an X frame 57, an X guide 58, an X drive unit 61, and an X slider (feed table) 59. The X-frame 57 is box-shaped and extends in the X-axis direction. The X-frame 57 is fastened to the mounting flange 47a. The X-axis extends perpendicular to the sixth axis J6. The X-guide 58 is positioned on the X-frame 57 and extends in the direction of the X-axis. The X slider 59 is positioned on the X guide 58. Guided by the X guide 58, the X slider 59 reciprocates in the X-axis direction. The X drive unit 61 includes an X motor 61a and an X lead screw 61b. The X motor 61a is located on the X frame 57. The X lead screw 61b is located on the X frame 57 and is connected to the X motor 61a. The X lead screw 61b is, for example, a ball screw. The X motor 61a rotates the X lead screw 61b to move the X slider 59.

[0026] The single-axis machining unit 63 includes a body 65, a Z guide 66, a Z slider 67, a ram (feed table) 69, a spindle motor 73, a spindle 71, a Z motor 75, and a Z feed screw 76. The body 65 is fastened to the X slider 59. The body 65 is box-shaped and extends in the Z direction. The Z direction is perpendicular to the sixth axis J6 and the X axis, respectively. The Z direction is the axis direction. The body 65 has a ram hole 65a. The ram hole 65a extends along the spindle 71.

[0027] The Z guide 66 is positioned on the body 65. The Z guide 66 extends in the Z direction. The Z slider 67 is positioned on the Z guide 66. Guided by the Z guide 66, the Z slider 67 reciprocates in the Z direction. The ram 69 is a straight cylinder. The ram 69 is fastened to the Z slider 67 and extends in the Z direction. The ram 69 passes through the ram hole 65a. The ram 69 is guided by the Z guide 66 and the ram hole 65a. The spindle 71 is rotatably supported by the ram 69. The spindle 71 extends in the Z direction. A tool 72 is mounted on the spindle 71. The spindle motor 73 is positioned on the Z slider 67. The spindle motor 73 is connected to the spindle 71 and rotates the spindle 71. The Z motor 75 is located in the body 65. The Z lead screw 76 extends in the Z direction and is rotatably located in the body 65. The Z lead screw 76 is connected to the Z motor 75 and drives the Z slider 67.

[0028] Note that the slide unit 56 may be omitted. In this case, the body 65 is fastened to the mounting flange 47a.

[0029] Figure 3 shows the detailed structure of the second joint J2. Figure 3 is a cross-sectional view taken through a plane passing through the second axis J2. The structure of the first joint J1 and the third to sixth joints J3 to J6 are substantially identical to that of the second joint J2.

[0030] As shown in Figure 3, the second joint J2 has a second bearing 25. The second bearing 25 is, for example, a cross roller bearing. The first link 15 has a second boss hole 15a. The second boss hole 15a extends along the second shaft J2. The second link 21 has a second shaft 21b. The second shaft 21b is a hollow shaft. The second shaft 21b is inserted into the second boss hole 15a. The second shaft 21b is supported in the second boss hole 15a via a second bearing 25. The second reduction gear 24 is inserted inside the second shaft 21b. The second motor 23 is located on the first link 15. The second motor 23 is connected to the second reduction gear 24.

[0031] The second brake 22 is an excitation-operated electromagnetic brake. The second brake 22 includes a stator 22a, a coil 22b, a lining 22c, an armature hub 22d, an elastic body 22e, and an armature 22f. The components constituting the second brake 22 are arranged around the second shaft J2. The stator 22a is fastened to the first link 15. The coil 22b is positioned on the stator 22a. The lining 22c is positioned on the front surface of the stator 22a. The front surface of the stator 22a is the surface facing the second link 21.

[0032] The armature hub 22d is fastened to the second link 21. The armature 22f is positioned on the armature hub 22d and reciprocates in the direction of the second axis J2. The armature 22f faces the lining 22c. The elastic body 22e is positioned between the armature hub 22d and the armature 22f. The elastic body 22e biases the armature 22f toward the armature hub 22d. When coil 22b is energized, it becomes energized and attracts the armature 22f. Then, the armature 22f and the lining 22c come into contact, suppressing the rotation of the first link 15 and the second link 21.

[0033] The processing method of this embodiment will be described with reference to Figure 4. In step S1, the robot arm 11 moves the end effector 55, and then positions the tool 72 opposite the workpiece 1 (see Figure 2). In step S2, the robot arm 11 stops. As a result, the position of the end effector 55 also stops. In step S3, the robot arm 11 is braked by the first to sixth brakes 16, 22, 30, 36, 42, and 48. At this time, the robot arm 11 maintains a servo-on state. In step S4, the end effector 55 rotates the spindle 71 and feeds out the spindle 71 to machine the workpiece 1. After machining is complete, the process proceeds to step S5. In step S5, the first to sixth brakes 16, 22, 30, 36, 42, and 48 release the braking force of the first to sixth joints J1 to J6, respectively.

[0034] The following will explain in detail the case where step S4 is a drilling operation, referring to Figure 2. First, the spindle motor 73 rotates the spindle 71. The X motor 61a moves the spindle 71 to a predetermined position in the X direction. Then, the Z motor 75 feeds the ram 69 in the Z direction. The tool 72 comes into contact with the workpiece 1 and drills a hole. When the predetermined depth is reached, the Z motor 75 pulls back the ram 69. After that, the spindle motor 73 stops the spindle 71.

[0035] Next, we will describe in detail the case where step S4 is a milling operation. First, the spindle motor 73 rotates the spindle 71. Then, the Z motor 75 feeds the ram 69 in the Z direction. The tool 72 makes contact with the workpiece 1 and cutting begins. Next, the X motor 61a feeds the X slider 59 in the X direction. When the machining length reaches a predetermined length, the Z motor 75 retracts the ram 69. After that, the spindle motor 73 stops the spindle 71.

[0036] The first to sixth joints J1 to J6 have backlash. According to the prior art, when the tool contacts the workpiece and cutting begins, the end effector receives a cutting reaction force. At this time, the angle of the first to sixth joints J1 to J6 changes rapidly due to the cutting reaction force received by the end effector. This causes the position of the end effector to shift. In addition, the first to sixth motors 17, 23, 31, 37, 43, and 49 attempt to return the angle of the first to sixth axes J1 to J6 to its original position. As a result, the position of the end effector is displaced during cutting, and the cutting accuracy (e.g., dimensional accuracy, surface roughness) decreases.

[0037] In the robot machining method of this embodiment, before the end effector 55 starts cutting, in step S3, the first to sixth brakes 16, 22, 30, 36, 42, and 48 brake the rotation of the first to sixth joints J1 to J6. Therefore, in step S4, when the end effector 55 performs cutting, deformation of the robot arm 11 is suppressed. As a result, displacement of the position of the end effector 55 during cutting is suppressed, and cutting accuracy is improved.

[0038] Furthermore, after the processing is complete, in step S5, the first to sixth brakes 16, 22, 30, 36, 42, and 48 release the braking force on the rotation of the first to sixth joints J1 to J6. As a result, the robot arm 11 can freely change its posture.

[0039] The first to sixth brakes 16, 22, 30, 36, 42, and 48 brake the adjacent links of the first to sixth joints J1 to J6. Therefore, even if the first to sixth reduction gears 18, 24, 32, 38, 44, and 50 have backlash, the adjacent links of the first to sixth joints J1 to J6 do not move freely during braking.

[0040] The first to sixth brakes 16, 22, 30, 36, 42, and 48 are excitation-operated electromagnetic brakes. When the first to sixth brakes 16, 22, 30, 36, 42, and 48 are not excited, the first to sixth joints J1 to J6 can rotate freely. While the robot arm 11 is moving, there is a possibility of power loss or power line breakage to the first to sixth brakes 16, 22, 30, 36, 42, and 48. In this case, the first to sixth joints J1 to J6 are not braked, and the robot arm 11 can continue moving. This helps to suppress failure of the robot arm 11.

[0041] Through steps S3 to S5, the robot arm 11 is servo-activated. Therefore, the robot arm 11 can temporarily stop during the execution of the operating program to perform the cutting operation in step S4 on the end effector 55. After the execution of step S5, the operating program can be resumed.

[0042] The end effector 55 can advance the spindle 71 in the X and Z directions. Therefore, in addition to drilling and tapping, the end effector 55 can perform milling operations.

[0043] <Second Embodiment> As shown in Figure 5, the robotic machining center 100 of this embodiment has a robotic arm 111 and an end effector 55. The robotic arm 111 has first to sixth worm gear reducers (braking mechanisms) 116, 122, 130, 136, 142, and 148 instead of first to sixth brakes 16, 22, 30, 36, 42, and 48. The robotic arm 111 also has first to sixth motors 117, 123, 131, 137, 143, and 149 instead of first to sixth motors 17, 23, 31, 37, 43, and 49. The other configurations of the robotic arm 111 are substantially the same as those of the robotic arm 11 of the first embodiment.

[0044] The first to sixth worm gear reducers 116, 122, 130, 136, 142, and 148 are connected to the first to sixth motors 117, 123, 131, 137, 143, and 149, respectively.

[0045] The first worm gear reducer 116 is positioned on the first link 15. The first worm gear reducer 116 has a first worm 116a and a first worm wheel 116b. The first worm 116a is connected to the first motor 117. The first worm wheel 116b is connected to the base 13 and meshes with the first worm 116a. The first worm gear reducer 116 reduces the power of the first motor 117 to rotate the first link 15 relative to the base 13. The first worm gear reducer 116 brakes the rotation of the first link 15 relative to the base 13.

[0046] The second worm gear reducer 122 is positioned on the first link 15. The second worm gear reducer 122 reduces the power of the second motor 123 and transmits it to the second link 21. The second worm gear reducer 122 brakes the rotation of the second link 21 relative to the first link 15.

[0047] The third worm gear reducer 130 is positioned on the second link 21. The third worm gear reducer 130 reduces the power of the third motor 131 and transmits it to the third link 29. The third worm gear reducer 130 brakes the rotation of the third link 29 relative to the second link 21.

[0048] The fourth worm gear reducer 136 is positioned on the third link 29. The fourth worm gear reducer 136 reduces the power of the fourth motor 137 and transmits it to the fourth link 35. The fourth worm gear reducer 136 brakes the rotation of the fourth link 35 relative to the third link 29.

[0049] The fifth worm gear reducer 142 is positioned on the fourth link 35. The fifth worm gear reducer 142 reduces the power of the fifth motor 143 and transmits it to the fifth link 41. The fifth worm gear reducer 142 brakes the rotation of the fifth link 41 relative to the fourth link 35.

[0050] The sixth worm gear reducer 148 is positioned on the fifth link 41. The sixth worm gear reducer 148 reduces the power of the sixth motor 149 and transmits it to the sixth link 47. The sixth worm gear reducer 148 brakes the rotation of the sixth link 47 relative to the fifth link 41.

[0051] The structures of the second to sixth worm gear reducers 122, 130, 136, 142, and 148 are substantially identical to those of the first worm gear reducer 116.

[0052] According to this embodiment, since the braking mechanism consists of the first to sixth worm gear reducers 116, 122, 130, 136, 142, and 148, the first to sixth motors 117, 123, 131, 137, 143, and 149 can rotate the first to sixth joints J1 to J6. In addition, the machining reaction force acting on the end effector 55 suppresses the rotation of the first to sixth joints J1 to J6.

[0053] Since the first to sixth worm gear reducers 116, 122, 130, 136, 142, and 148 also serve as gear reducers for the first to sixth joints J1 to J6, the structure of the robot arm 111 can be simplified.

[0054] <Third Embodiment> As shown in Figure 6, the robotic machining center 200 of this embodiment has an end effector 255 instead of the end effector 55 of the first embodiment. The other configurations of the robotic machining center 200 are substantially the same as those of the robotic machining center 10 of the first embodiment.

[0055] The end effector 255 has a slide unit 56 and a spindle unit 263. The spindle unit 263 has a spindle head 269, a spindle 71, and a spindle motor 73. The spindle head 269 is fastened to the X slider 59. The spindle head 269 rotatably supports the spindle 71. The spindle 71 extends in the Z direction. The spindle motor 73 is positioned on the spindle head 269. The spindle motor 73 is connected to the spindle 71. The spindle motor 73 rotates the spindle 71.

[0056] In the robotic machining center 200 of this embodiment, the spindle 71 is moved in the X direction by the X slider 59. Therefore, the robotic machining center 200 can perform milling and end milling.

[0057] <Fourth Embodiment> As shown in Figure 7, the robotic machining center 300 of this embodiment includes a travel unit 356, a robotic arm 11, and an end effector 55. The end effector 55 is positioned on the sixth link 47. Figure 7 shows a cross-sectional view of the travel unit 356 in the XY plane.

[0058] The travel unit 356 includes a frame 357, an arm travel guide 358, an arm base (feed table) 359, and a travel drive unit 361. The frame 357 is installed on the floor. The frame 357 extends in the Z direction (perpendicular to the plane of the paper). The arm travel guide 358 is positioned on the frame 357 and extends in the Z direction. The arm base 359 is positioned on the arm travel guide 358 and reciprocates in the Z direction guided by the arm travel guide 358. The base 13 is fastened to the arm base 359.

[0059] The travel drive unit 361 includes a travel motor 361a, a pinion 361b, and a rack 361c. The travel motor 361a is positioned on the arm base 359. The rack 361c extends in the Z direction and is positioned on the frame 357. The pinion 361b is connected to the travel motor 361a. The pinion 361b meshes with the rack 361c. Note that the slide unit 56 may be omitted.

[0060] The robot arm 11 swings the slide unit 56. It is difficult to make the length of the slide unit 56 in the X direction extremely long. According to the robot machining machine 10 of Embodiment 1, the width that can be machined at one time is limited to the width of the slide unit 56.

[0061] According to the robot machining center 300 of this embodiment, the travel unit 356 can be extended as far as the installation space allows. With the first to sixth joints J1 to J6 of the robot arm 11 braked, the arm base 359 can feed the spindle 71 in the X direction. Therefore, the robot machining center 300 can machine a workpiece 1 that extends long in the horizontal direction (Z direction in Figure 7) over a long horizontal range.

[0062] Since the robot arm 11 has six axes, the orientation of the end effector 55 can be freely changed. The robot arm 11 can change the orientation of the end effector 55 so that the X axis extends in the vertical direction. In this state, the travel unit 356 stops and the slide unit 56 moves the spindle 71. As a result, the robot machining center 300 can machine even short sections in the vertical direction.

[0063] The present invention is not limited to the embodiments described above, and various modifications are possible without departing from the spirit of the invention. All technical matters included in the technical concept described in the claims are covered by the present invention. The embodiments described above are preferred examples, but those skilled in the art can realize various alternatives, modifications, variations, or improvements from the contents disclosed herein, and these are included in the technical scope described in the appended claims. [Explanation of symbols]

[0064] 10, 100, 200, 300 robotic machining centers 11,111 Robot Arm 16, 22, 30, 36, 42, 48 Brakes (braking mechanism) 55, 255 End Effector 59 X-slider (feed table) 69 Ram (feed stand) 116, 122, 130, 136, 142, 148 Worm gear reducer (braking mechanism) 359 Arm stand (feed stand)

Claims

1. A multi-jointed robotic arm, Multiple joints, A braking mechanism capable of braking the rotation of at least one of the multiple joints while the servo is on, A robotic arm having, An end effector positioned at the tip of the robot arm, the end effector having a tool mountable and rotatable spindle, A feed table for advancing the main spindle, A robotic machining center.

2. The robot arm is a vertical multi-joint robot arm. The robotic processing machine according to claim 1.

3. The end effector further includes a feed guide, The feed table is positioned on the feed guide and is fed along the feed guide. A robotic machining center according to claim 1 or 2.

4. The system further includes an arm travel guide that holds the aforementioned feed table, The feed platform supports the robot arm and is moved along the arm travel guide. A robotic processing machine according to claim 1 or 2.

5. The feed guide extends in the direction in which the main spindle extends. A robotic machining center according to claim 1 or 2.

6. The braking mechanism is a brake that brakes the two links connected to the joint. A robotic machining center according to any one of claims 1 to 5.

7. The braking mechanism is an electromagnetic brake. The robotic processing machine according to claim 6.

8. The robot arm has motors that drive each of the joints, The braking mechanism is a worm gear reducer connected to the motor. A robotic machining center according to any one of claims 1 to 5.

9. The braking mechanism is capable of braking the rotation of only the distal joint among the plurality of joints. A robotic machining center according to any one of claims 1 to 8.

10. A multi-jointed robotic arm having a braking mechanism that brakes each of the two links connected to each of its multiple joints.

11. The braking mechanism is a brake that brakes between the two links connected to the joint. The robot arm according to claim 10.

12. A machining method using a multi-joint robot arm having an end effector, The robot arm stops the position of the end effector, The joints of the robot arm are braked, The end effector rotates the spindle, and the feed table moves the spindle to process the workpiece. After the processing is complete, the braking of the joint of the robot arm is released. Processing method.

13. While the servos of the robot arm remain on, the joints of the robot arm are braked. The processing method according to claim 12.

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