Horizontal articulated robot

Abstract

This horizontal articulated robot (10) is provided with a base part (14) and a robot body (16). The robot body is provided with a first arm (30), a second arm (32), a first motor (36), a second motor (40), a first power transmission part (38), and a second power transmission part (42). The first arm is positioned below the base part, the second arm is positioned below the first arm, and the second motor is positioned so as not to interfere with the second arm in a state in which the tip (32t) of the second arm is located below the first arm.

Description

Horizontal articulated robot

[0001] The present invention relates to a horizontal articulated robot.

[0002] International Publication No. 2020 / 136890 discloses a horizontal articulated robot including a base and a robot main body supported on the base. The robot main body includes a first arm rotatable about a first axis relative to the base, and a second arm rotatable about a second axis relative to the first arm. The first arm is located above the base, and the second arm is located below the first arm.

[0003] A better horizontal articulated robot is needed.

[0004] The present disclosure aims to solve the above-mentioned problems.

[0005] One aspect of the present disclosure is a horizontally articulated robot comprising: a base portion; and a robot main body supported on the base portion, wherein the robot main body comprises: a first arm rotatably mounted on the base portion about a first axis; a second arm rotatably mounted on the first arm about a second axis; a first motor mounted on the base portion and rotating the first arm; a second motor mounted on the first arm and rotating the second arm; a first power transmission unit that transmits a rotational drive force of the first motor to the first arm; and a second power transmission unit that transmits a rotational drive force of the second motor to the second arm, wherein the first arm is positioned below the base portion, the second arm is positioned below the first arm, and the second motor is positioned so as not to interfere with the second arm when the tip of the second arm is positioned below the first arm.

[0006] According to the present disclosure, a better horizontal articulated robot can be provided.

[0007] FIG. 1 is a perspective view of a horizontal articulated robot according to an embodiment. FIG. 2 is a longitudinal cross-sectional view of the horizontal articulated robot, with some parts omitted. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 2. FIG. 5 is a cross-sectional view taken along line V-V in FIG. 2. FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 2. FIG. 7 is an explanatory diagram of the operation of the horizontal articulated robot.

[0008] The present disclosure can provide a horizontally articulated robot that can widen the range of motion of the second arm relative to the first arm while making the robot body compact.

[0009] A horizontal articulated robot according to an embodiment of the present disclosure will be described below with reference to the drawings. As shown in Fig. 1, the horizontal articulated robot 10 according to this embodiment is a robot used to automatically perform tasks such as milking cows in dairy farming. The horizontal articulated robot 10 is not limited to this, and may also be used to perform tasks such as workpiece removal, workpiece assembly, screw tightening, and adhesive application.

[0010] 1 and 2, the horizontal articulated robot 10 includes a lifting unit 12, a base 14, and a robot body 16. The lifting unit 12 includes a unit body 18, a slider 20, and a lifting motor 22. The unit body 18 extends in the vertical direction (Z direction). The slider 20 is provided so as to be slidable in the vertical direction relative to the unit body 18 (see FIG. 2).

[0011] As shown in Fig. 1, the lift motor 22 moves the slider 20 in the up and down direction. The lift motor 22 moves the slider 20 in the up and down direction, for example, by rotating a ball screw (not shown). The lift motor 22 is disposed at the upper end of the unit body 18. The lift unit 12 is not limited to the configuration described above. Furthermore, the lift unit 12 may include components other than those described above.

[0012] 1 and 2 , the base portion 14 supports the robot body 16 while attached to the slider 20. In other words, the base portion 14 supports the robot body 16 in a suspended state. The base portion 14 includes a connection portion 24, a bracket 26, and a base body 28. The connection portion 24 connects the slider 20 and the bracket 26 to each other. The bracket 26 supports the base body 28. The robot body 16 is attached to the base body 28.

[0013] The robot body 16 has a first arm 30, a second arm 32, a tool mounting portion 34, a first motor 36, a first power transmission portion 38, a second motor 40, a second power transmission portion 42, a third motor 44, and a third power transmission portion 46.

[0014] As shown in FIG. 2, the first arm 30 is located below the base portion 14 (in the Z1 direction). The first arm 30 is rotatable about a first axis Ax1 relative to the base portion 14. The first axis Ax1 extends in the vertical direction. The first arm 30 extends in the horizontal direction. The first arm 30 is hollow. The first arm 30 has a rectangular cross-sectional shape (see FIG. 4). The first arm 30 has a first upper wall portion 30a, a first lower wall portion 30b, and a first peripheral wall portion 30c.

[0015] The second arm 32 is located below the first arm 30 (in the Z1 direction). The second arm 32 is rotatable about a second axis Ax2 relative to the first arm 30. The second axis Ax2 extends in the vertical direction. The second axis Ax2 extends parallel to the first axis Ax1. The second arm 32 extends horizontally. The second arm 32 is hollow. The second arm 32 has a rectangular cross-sectional shape (see FIG. 4). The second arm 32 has a second upper wall portion 32a, a second lower wall portion 32b, and a second circumferential wall portion 32c. The length (total length) of the second arm 32 along the extension direction is shorter than the length (total length) of the first arm 30 along the extension direction. As shown in FIG. 4, the length W2 of the second arm 32 along the width direction is shorter than the length W1 of the first arm 30 along the width direction. The width direction is a direction perpendicular to the extending direction of the second arm 32 and the up-down direction.

[0016] As shown in FIGS. 1, 2, and 6, the tool mounting portion 34 is located below the second arm 32. The tool mounting portion 34 is rotatable about a third axis Ax3 (see FIG. 2) relative to the second arm 32. In the horizontal direction, the distance between the first axis Ax1 and the second axis Ax2 is longer than the distance between the second axis Ax2 and the third axis Ax3 (see FIG. 2). The tool mounting portion 34 is formed, for example, in a cylindrical shape. The tool mounting portion 34 extends in the vertical direction. A tool 200 is mounted to the tool mounting portion 34. In other words, the tool 200 is detachable from the tool mounting portion 34.

[0017] 1 , the tool 200 is, for example, a milking machine for milking cows. The tool 200 is not limited to a milking machine. The tool 200 may be modified as appropriate depending on the application of the horizontal articulated robot 10. In this embodiment, the tool 200 may be a part of the components of the horizontal articulated robot 10.

[0018] 2, the first motor 36 rotates the first arm 30 about a first axis Ax1. The first motor 36 is attached to the base body 28. The first axis Ax1 passes through the axis of a first rotation shaft 36a of the first motor 36.

[0019] The first power transmission unit 38 transmits the rotational driving force of the first motor 36 to the first arm 30. The first power transmission unit 38 has a connecting unit 47 and a first harm gear mechanism 48. The connecting unit 47 connects the first rotating shaft 36a to the first harm gear mechanism 48. The first harm gear mechanism 48 includes a first input unit 50, a first output unit 52, a first harm main body unit 54, and a first support unit 56.

[0020] The first input unit 50 is attached to the first rotating shaft 36a via the connecting unit 47. The first output unit 52 is formed in an annular shape. The first input unit 50 is located in an inner hole of the first output unit 52. The lower end of the first output unit 52 is attached to the first upper wall unit 30a of the first arm 30 with a plurality of screw members 55. In other words, the first output unit 52 is fixed to the first arm 30. The first output unit 52 is attached to a middle portion of the first arm 30 in the extension direction. The first output unit 52 may also be attached to one end of the first arm 30.

[0021] The first wave body 54 is interposed between the first input section 50 and the first output section 52. The first wave body 54 transmits the rotational force of the first input section 50 to the first output section 52. The first wave body 54 includes a speed reduction mechanism (not shown). That is, the first wave body 54 reduces the rotational speed of the first output section 52 compared to the rotational speed of the first input section 50. The first support section 56 is fixed to the base body 28 by a plurality of screw members 57. The first support section 56 rotatably supports each of the first input section 50 and the first output section 52. The first support section 56 has bearings (not shown). The bearings include, for example, rolling bearings, cross roller bearings, etc.

[0022] The second motor 40 rotates the second arm 32 about the second axis Ax2. The second motor 40 is attached to the first arm 30. In this embodiment, the second motor 40 is disposed on the lower surface 31 of the first arm 30. In other words, the second motor 40 is fixed to the first lower wall portion 30b. The second motor 40 is located at one end of the first arm 30. The second rotation shaft 40a of the second motor 40 protrudes into the first arm 30. The second rotation shaft 40a of the second motor 40 is located in the opposite direction from the second axis Ax2 relative to the first axis Ax1. The entire second motor 40 is located in the opposite direction from the second axis Ax2 relative to the first axis Ax1.

[0023] The second power transmission unit 42 transmits the rotational driving force of the second motor 40 to the second arm 32. The second power transmission unit 42 has a first drive pulley 58, a first driven pulley 60, a first belt 62, and a second harmonic gear mechanism 64.

[0024] 2 and 3 , the first drive pulley 58, the first driven pulley 60, and the first belt 62 are disposed inside the first arm 30. The first drive pulley 58 is formed in an annular shape. The first drive pulley 58 is attached to the second rotary shaft 40a of the second motor 40. In other words, the first drive pulley 58 is located at one end of the first arm 30. The first driven pulley 60 is attached to the second harmonic gear mechanism 64.

[0025] The first driven pulley 60 is located at the other end of the first arm 30. The first driven pulley 60 is formed in an annular shape. The second axis Ax2 passes through the center of the first driven pulley 60. The first driven pulley 60 rotates about the second axis Ax2 (see FIG. 4). The first driven pulley 60 is located horizontally relative to the first driving pulley 58. The outer diameter of the first driven pulley 60 is larger than the outer diameter of the first driving pulley 58.

[0026] The first belt 62 is wound around the first drive pulley 58 and the first driven pulley 60. In other words, the first belt 62 is formed in a circular shape. Note that the first drive pulley 58, the first driven pulley 60, and the first belt 62 are not limited to the configurations described above.

[0027] As shown in FIG. 4 , the second harmonic gear mechanism 64 includes a second input portion 66, a second output portion 68, a second wave main portion 70, and a second support portion 72. The second input portion 66 is formed in an annular shape. The first driven pulley 60 is attached to the upper end of the second input portion 66. The second output portion 68 is also formed in an annular shape. The second input portion 66 is located in an inner hole of the second output portion 68. The second output portion 68 is attached to the second upper wall portion 32 a of the second arm 32 with a plurality of screw members 71. In other words, the second output portion 68 is fixed to the second arm 32. The second output portion 68 is attached to one end of the second arm 32 (see FIG. 2 ).

[0028] The second wave motion main body 70 is interposed between the second input portion 66 and the second output portion 68. The second wave motion main body 70 transmits the rotational force of the second input portion 66 to the second output portion 68. The second wave motion main body 70 includes a speed reduction mechanism (not shown). That is, the second wave motion main body 70 reduces the rotational speed of the second output portion 68 compared to the rotational speed of the second input portion 66. The second support portion 72 is fixed to the first arm 30 by a plurality of screw members 73. The second support portion 72 rotatably supports each of the second input portion 66 and the second output portion 68. The second support portion 72 has a bearing (not shown). The bearing may be, for example, a rolling bearing, a cross roller bearing, or the like.

[0029] As shown in FIG. 2 , the third motor 44 rotates the tool mounting portion 34 about the third axis Ax3. The third motor 44 is attached to the first arm 30. In this embodiment, the third motor 44 is disposed on the upper surface 33 of the first arm 30. In other words, the third motor 44 is fixed to the first upper wall portion 30a. The third motor 44 is located at a middle portion of the first arm 30 in the extension direction. The third rotation shaft 44a of the third motor 44 protrudes inside the first arm 30. The third motor 44 is located between the first axis Ax1 and the second axis Ax2.

[0030] The third power transmission unit 46 transmits the rotational driving force of the third motor 44 to the tool attachment unit 34. The third power transmission unit 46 has a second drive pulley 74, a first intermediate pulley 76, a second belt 78, a connecting unit 80, a second intermediate pulley 82, a second driven pulley 84, a third belt 86, a plurality of tension pulleys 87 (see FIG. 5 ), and a third harmonic gear mechanism 88.

[0031] 2 and 3, the second drive pulley 74 is attached to the third rotary shaft 44a of the third motor 44. The second drive pulley 74 is located above the first belt 62 (in the Z2 direction).

[0032] The first intermediate pulley 76 is formed in an annular shape. The first intermediate pulley 76 is located above the first driven pulley 60. The first intermediate pulley 76 rotates about a second axis Ax2 (see FIG. 4). The first intermediate pulley 76 is located horizontally relative to the second driving pulley 74 (see FIG. 2). The outer diameters of the second driving pulley 74 and the first intermediate pulley 76 are each smaller than the outer diameter of the first driving pulley 58.

[0033] The second belt 78 is wound around the second drive pulley 74 and the first intermediate pulley 76. In other words, the second belt 78 is formed in a circular shape. Note that the second drive pulley 74, the first intermediate pulley 76, and the second belt 78 are not limited to the configurations described above.

[0034] As shown in FIG. 4 , the coupling portion 80 is a shaft portion extending in the vertical direction. The first intermediate pulley 76 is coupled to the upper end of the coupling portion 80. The coupling portion 80 is inserted into an insertion hole 89, which is an inner hole of the first driven pulley 60, and an inner hole 91 of the second input portion 66. A gap is provided between the coupling portion 80 and the first driven pulley 60. This prevents the coupling portion 80 and the first driven pulley 60 from interfering with each other. Furthermore, a gap is provided between the coupling portion 80 and the second input portion 66. This prevents the coupling portion 80 and the second input portion 66 from interfering with each other. The lower end of the coupling portion 80 is located inside the second arm 32. The second intermediate pulley 82 is coupled to the lower end of the coupling portion 80. The second axis Ax2 passes through the centers of the first intermediate pulley 76, the coupling portion 80, and the second intermediate pulley 82.

[0035] The connecting portion 80 is rotatably supported with respect to the second power transmission portion 42. Specifically, the connecting portion 80 is rotatably supported with respect to the first driven pulley 60 via a first bearing 90. The connecting portion 80 is rotatably supported with respect to the second input portion 66 via a second bearing 92. Each of the first bearing 90 and the second bearing 92 may be a rolling bearing or a plain bearing.

[0036] 5, a second intermediate pulley 82, a second driven pulley 84, and a third belt 86 are disposed inside the second arm 32. The second intermediate pulley 82 is formed in an annular shape. The second intermediate pulley 82 is located at one end of the second arm 32.

[0037] The second driven pulley 84 is located at the other end of the second arm 32. The second driven pulley 84 is formed in an annular shape. The third axis Ax3 passes through the center of the second driven pulley 84. The second driven pulley 84 rotates about the third axis Ax3 (see FIG. 6). The second driven pulley 84 is located horizontally relative to the second intermediate pulley 82 (see FIG. 2). The outer diameter of the second driven pulley 84 is larger than the outer diameter of the second intermediate pulley 82.

[0038] The third belt 86 is wound around the second intermediate pulley 82 and the second driven pulley 84. In other words, the third belt 86 is formed in a circular shape. Note that the second intermediate pulley 82, the second driven pulley 84, and the second belt 78 are not limited to the above-described configurations.

[0039] The plurality of tension pulleys 87 adjust the tension of the third belt 86 by pressing the outer surface of the third belt 86 inward. Each tension pulley 87 is rotatably supported by a pulley support portion 93. The pulley support portion 93 is supported by the second arm 32.

[0040] As shown in FIG. 6 , the third strain wave gear mechanism 88 includes a third input portion 94, a third output portion 96, a third strain wave main portion 98, and a third support portion 100. The second driven pulley 84 is attached to the upper end of the third input portion 94. The third output portion 96 is formed in an annular shape. The third input portion 94 is located in an inner hole of the third output portion 96. The lower end of the third output portion 96 is attached to the tool mounting portion 34. That is, the third output portion 96 is fixed to the tool mounting portion 34 by a screw member (not shown).

[0041] The third wave body 98 is interposed between the third input portion 94 and the third output portion 96. The third wave body 98 transmits the rotational force of the third input portion 94 to the third output portion 96. The third wave body 98 includes a speed reduction mechanism (not shown). That is, the third wave body 98 reduces the rotational speed of the third output portion 96 compared to the rotational speed of the third input portion 94. The third support portion 100 is fixed to the second arm 32 by a screw member 101. The third support portion 100 rotatably supports each of the third input portion 94 and the third output portion 96. The third support portion 100 includes a bearing (not shown). The bearing may be, for example, a rolling bearing, a cross roller bearing, or the like.

[0042] 7 , in the horizontal articulated robot 10 described above, the distance L1 is shorter than the distance L2 in the horizontal direction (the direction perpendicular to the Z direction). The distance L1 is the shortest distance from the second axis Ax2 to the tip 32t of the second arm 32 that is the farthest from the second axis Ax2. The distance L2 is the shortest distance from the second axis Ax2 to the second motor 40.

[0043] That is, the second motor 40 is disposed in a position that does not interfere with the second arm 32 when the tip 32t of the second arm 32 is positioned below the first arm 30 (the state shown in FIG. 7 ). In this state, the second arm 32 is entirely covered from above by the first arm 30. This allows the robot body 16 of the horizontally articulated robot 10 to be made compact when the tip 32t of the second arm 32 is positioned below the first arm 30. That is, in this state, the horizontal dimension of the robot body 16 can be reduced. Therefore, the horizontally articulated robot 10 can be placed even in a relatively narrow space.

[0044] According to this embodiment, the tip 32t of the second arm 32 can be positioned below the first arm 30, which makes it possible to make the robot body 16 compact while widening the range of movement of the second arm 32 relative to the first arm 30. Therefore, a better horizontally articulated robot 10 can be provided.

[0045] The following additional notes are further disclosed regarding the above embodiment.

[0046] (Appendix 1) The horizontally articulated robot (10) of the present disclosure comprises a base (14) and a robot main body (16) supported on the base, the robot main body comprising: a first arm (30) rotatably provided around a first axis (Ax1) relative to the base; a second arm (32) rotatably provided around a second axis (Ax2) relative to the first arm; a first motor (36) provided on the base and rotating the first arm; a second motor (40) provided on the first arm and rotating the second arm; a first power transmission unit (38) that transmits the rotational driving force of the first motor to the first arm; and a second power transmission unit (42) that transmits the rotational driving force of the second motor to the second arm, the first arm being positioned below the base, the second arm being positioned below the first arm, and the second motor being positioned so as not to interfere with the second arm when a tip (32t) of the second arm is positioned below the first arm.

[0047] With this configuration, the tip of the second arm can be positioned below the first arm, which allows the range of motion of the second arm relative to the first arm to be widened while still making the robot body compact, thereby providing a better horizontally articulated robot.

[0048] (Supplementary Note 2) In the horizontal articulated robot described in Supplementary Note 1, the second motor may be arranged on the underside (31) of the first arm, and the distance (L1) from the second axis to the tip of the second arm in the horizontal direction may be shorter than the distance (L2) from the second axis to the second motor.

[0049] According to this simple configuration, interference between the second motor and the second arm can be avoided when the tip of the second arm is positioned below the first arm.

[0050] (Supplementary Note 3) In the horizontal articulated robot according to Supplementary Note 2, the second motor may be located in a direction opposite to the second arm with respect to the first axis.

[0051] With this configuration, the center of gravity of the robot body can be positioned closer to the first axis, thereby enabling the robot body to be stably supported by the base portion.

[0052] (Supplementary Note 4) In the horizontal articulated robot described in Supplementary Note 2 or 3, the robot body may include a tool mounting portion (34) rotatably mounted on the second arm about a third axis (Ax3) and having a tool (200) attached thereto, a third motor (44) that rotates the tool mounting portion, and a third power transmission portion (46) that transmits the rotational driving force of the third motor to the tool mounting portion, and the tool mounting portion may be located below the second arm, and the third motor may be provided on an upper surface (33) of the first arm.

[0053] With this configuration, the tool attachment portion can be rotated while keeping the configuration of the robot body compact.

[0054] (Supplementary Note 5) In the horizontal articulated robot described in Supplementary Note 4, the first arm may be hollow, the second power transmission unit may have a first drive pulley (58) connected to the second motor, a first driven pulley (60) located on the second axis, and a first belt (62) wound around the first drive pulley and the first driven pulley, and the second arm may rotate in accordance with the rotation of the first driven pulley, and the first drive pulley, the first driven pulley, and the first belt may be disposed inside the first arm.

[0055] With this configuration, the first drive pulley, the first driven pulley, and the first belt are arranged inside the first arm, so that the configuration of the robot body can be made compact while the first arm can be operated by the second motor.

[0056] (Supplementary Note 6) In the horizontal articulated robot according to Supplementary Note 5, the second arm may be hollow, the third power transmission unit may include a second drive pulley (74) connected to the third motor, a first intermediate pulley (76) and a second intermediate pulley (82) located on the second axis, a second belt (78) wound around the second drive pulley and the first intermediate pulley, a connecting unit (80) connecting the first intermediate pulley and the second intermediate pulley to each other, a second driven pulley (84) located on the third axis, and a third belt (86) wound around the second intermediate pulley and the second driven pulley, the tool attachment unit may rotate in accordance with rotation of the second driven pulley, the second drive pulley, the first intermediate pulley, and the second belt may be disposed inside the first arm, and the second intermediate pulley, the second driven pulley, and the third belt may be disposed inside the second arm.

[0057] With this configuration, the second drive pulley, the first intermediate pulley, and the second belt are disposed inside the first arm, and the second intermediate pulley, the second driven pulley, and the third belt are disposed inside the second arm, which allows the second arm to be operated by the third motor while keeping the configuration of the robot main body compact.

[0058] (Supplementary Note 7) In the horizontal articulated robot according to Supplementary Note 6, the first driven pulley may be formed with an insertion hole (89) through which the connecting portion is inserted.

[0059] With this configuration, it is possible to prevent the driven pulley and the connecting portion from interfering with each other.

[0060] (Supplementary Note 8) In the horizontal articulated robot according to Supplementary Note 6 or 7, the second belt may be positioned higher than the first belt.

[0061] With this configuration, it is possible to prevent the first belt and the second belt from interfering with each other.

[0062] Although the present disclosure has been described in detail, the present disclosure is not limited to the individual embodiments described above. Various additions, substitutions, modifications, partial deletions, etc. are possible in these embodiments without departing from the gist of the present disclosure or the spirit of the present disclosure derived from the content of the claims and their equivalents. These embodiments can also be implemented in combination. For example, in the above-described embodiments, the order of each operation and the order of each process are shown as examples and are not limited to these. The same applies when numerical values ​​or mathematical expressions are used in the description of the above-described embodiments.

[0063] DESCRIPTION OF SYMBOLS 10...Horizontal articulated robot 14...Base portion 16...Robot body 30...First arm 31...Underside 32...Second arm 32t...Tip 33...Upper surface 34...Tool mounting portion 36...First motor 38...First power transmission portion 40...Second motor 42...Second power transmission portion 44...Third motor 46...Third power transmission portion 58...First driving pulley 60...First driven pulley 62...First belt 74...Second driving pulley 76...First intermediate pulley 78...Second belt 80...Connecting portion 82...Second intermediate pulley 84...Second driven pulley 86...Third belt 89...Through-hole 200...Tool Ax1...First axis Ax2...Second axis Ax3...Third axis

Claims

1. A robot comprising: a base portion (14); and a robot body (16) supported on the base portion, wherein the robot body comprises: a first arm (30) rotatably provided on the base portion about a first axis (Ax1); a second arm (32) rotatably provided on the first arm about a second axis (Ax2); a first motor (36) provided on the base portion and rotating the first arm; a second motor (40) provided on the first arm and rotating the second arm; a first power transmission unit (38) that transmits the rotational driving force of the first motor to the first arm; and a second power transmission unit (42) that transmits the rotational driving force of the second motor to the second arm, wherein the first arm is located below the base portion; and the second arm is located below the first arm. The second motor is positioned so as not to interfere with the second arm when the tip (32t) of the second arm is positioned below the first arm.

2. A horizontal articulated robot according to claim 1, wherein the second motor is disposed on the underside (31) of the first arm, and the distance (L1) from the second axis to the tip of the second arm in the horizontal direction is shorter than the distance (L2) from the second axis to the second motor.

3. A horizontal articulated robot according to claim 2, wherein the second motor is positioned in the opposite direction from the second arm relative to the first axis.

4. A horizontal articulated robot as set forth in claim 2, wherein the robot body comprises: a tool mounting section (34) rotatably mounted on the second arm about a third axis (Ax3) and having a tool (200) mounted thereon; a third motor (44) that rotates the tool mounting section; and a third power transmission section (46) that transmits the rotational driving force of the third motor to the tool mounting section, wherein the tool mounting section is located below the second arm, and the third motor is mounted on the upper surface (33) of the first arm.

5. A horizontal articulated robot according to claim 4, wherein the first arm is hollow, the second power transmission section has a first drive pulley (58) connected to the second motor, a first driven pulley (60) located on the second axis, and a first belt (62) wound around the first drive pulley and the first driven pulley, the second arm rotates in conjunction with the rotation of the first driven pulley, and the first drive pulley, the first driven pulley and the first belt are disposed inside the first arm.

6. A horizontal articulated robot according to claim 5, wherein the second arm is hollow, the third power transmission unit has a second drive pulley (74) connected to the third motor, a first intermediate pulley (76) and a second intermediate pulley (82) located on the second axis, a second belt (78) wound around the second drive pulley and the first intermediate pulley, a connecting unit (80) connecting the first intermediate pulley and the second intermediate pulley to each other, a second driven pulley (84) located on the third axis, and a third belt (86) wound around the second intermediate pulley and the second driven pulley, the tool mounting unit rotates in accordance with the rotation of the second driven pulley, the second drive pulley, the first intermediate pulley and the second belt are disposed inside the first arm, The second intermediate pulley, the second driven pulley, and the third belt are disposed inside the second arm.

7. A horizontally articulated robot according to claim 6, wherein the first driven pulley is formed with an insertion hole (89) through which the connecting portion is inserted.

8. A horizontally articulated robot according to claim 6, wherein the second belt is positioned higher than the first belt.

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