robot

Abstract

To provide a robot which can inhibit increase in electrical power consumption.SOLUTION: A robot includes: a base; a first arm which is connected to the base and rotates around a first axis; a second arm which is connected to the first arm and rotates around a second axis parallel to the first axis; a first shaft which is connected to the second arm and moves in an axial direction of a third axis parallel to the second axis or rotates around the third axis; and a motor which is provided at the second arm and driven to move the first shaft in the axial direction of the third axis or rotate the first shaft around the third axis. The motor is located opposite the first shaft with respect to the second axis.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a robot.

Background Art

[0002] In recent years, in factories, due to the soaring labor costs and labor shortages, the automation of operations that have been performed manually has been accelerating with various robots and their peripheral devices. Examples of such various robots include scalar robots as described in Patent Document 1.

[0003] The scalar robot described in Patent Document 1 includes a base, a first arm connected to the base, a second arm connected to the first arm, a work axis connected to the second arm and capable of moving up and down and rotating, and a work axis lifting mechanism for lifting the work axis.

[0004] The work axis lifting mechanism has a lifting belt that transmits the driving force of a work axis lifting motor via a drive pulley and a driven pulley, a vertical movement bracket that rotatably holds the work axis while being fixed to the lifting belt and moves up and down integrally with the work axis as the lifting belt is conveyed, and a guide shaft that guides the up and down movement of the vertical movement bracket.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in the scalar robot described in Patent Document 1, due to the arrangement of each component, the center of gravity is unevenly distributed on the tip side of the second arm. For this reason, there is a risk of problems such as an increase in inertia for driving the robot arm and an increase in power consumption. [Means for solving the problem]

[0007] This invention was made to solve at least some of the aforementioned problems and can be realized as follows.

[0008] The robot of the present invention comprises a base and A first arm connected to the base and rotating around a first axis, A second arm connected to the first arm and rotating around a second axis parallel to the first axis, A first shaft connected to the second arm moves in the axial direction of a third axis parallel to the second axis, or rotates around the third axis, The second arm is provided with a motor that drives the first shaft to move in the axial direction of the third axis or to rotate it around the third axis, The motor is characterized in that it is located on the opposite side of the first shaft from the second shaft. [Brief explanation of the drawing]

[0009] [Figure 1] This is a side view showing a first embodiment of a robot system comprising the robot of the present invention. [Figure 2] Figure 1 is a block diagram of the robot system shown. [Figure 3] This is a partial cross-sectional view showing the inside of the second arm of the robot arm shown in Figure 1. [Figure 4] This is a partial cross-sectional view showing the inside of a second arm in a second embodiment of a robot system comprising the robot of the present invention. [Figure 5] This is a partial cross-sectional view showing the inside of a second arm in a third embodiment of a robot system comprising the robot of the present invention. [Figure 6] This is a partial cross-sectional view showing the inside of a second arm in a fourth embodiment of a robot system comprising the robot of the present invention. [Modes for carrying out the invention]

[0010] The robot of the present invention will be described in detail below based on preferred embodiments shown in the accompanying drawings. <First Embodiment> Figure 1 is a side view showing a first embodiment of a robot system comprising the robot of the present invention. Figure 2 is a block diagram of the robot system shown in Figure 1. Figure 3 is a partial cross-sectional view showing the interior of the second arm of the robot arm shown in Figure 1.

[0011] Furthermore, in Figures 1 and 3, for the sake of explanation, the x, y, and z axes are depicted as three mutually orthogonal axes. In the following, the direction parallel to the x-axis will also be referred to as the "x-axis direction," the direction parallel to the y-axis as the "y-axis direction," and the direction parallel to the z-axis as the "z-axis direction." In the following, the tip of each arrow shown will be referred to as "+ (plus)" and the base as "- (minus)." The direction parallel to the +x-axis will also be referred to as the "+x-axis direction," the direction parallel to the -x-axis direction as the "-x-axis direction," the direction parallel to the +y-axis direction as the "+y-axis direction," the direction parallel to the -y-axis direction as the "-y-axis direction," the direction parallel to the +z-axis direction as the "+z-axis direction," and the direction parallel to the -z-axis direction as the "-z-axis direction." In addition, the direction around the z-axis and the direction around the axis parallel to the z-axis will also be referred to as the "u-axis direction."

[0012] Furthermore, for the sake of clarity, in the following explanation, the +z-axis direction in Figure 1, i.e., the upper side, will also be referred to as "up" or "upward," and the -z-axis direction, i.e., the lower side, will also be referred to as "down" or "downward." In addition, for the robot arm 20, the side facing the base 21 in Figure 1 will be referred to as the "base end," and the opposite side, i.e., the end effector 7 side, will be referred to as the "tip end." Also, in Figure 1, the z-axis direction, i.e., the up and down direction, will be referred to as the "vertical direction," and the x-axis and y-axis directions, i.e., the left and right directions, will be referred to as the "horizontal direction."

[0013] The robot system 100 shown in FIGS. 1 and 2 is a device used for operations such as holding, transporting, assembling, and inspecting workpieces such as electronic components and electronic devices. The robot system 100 includes a control device 1, a robot 2, and an end effector 7.

[0014] In addition, the control device 1 is located at a position different from that of the robot 2, that is, outside the robot 2. In the illustrated configuration, the robot 2 and the control device 1 are electrically connected (hereinafter, simply referred to as "connected") by a cable 200, but it is not limited thereto, and the cable 200 may be omitted and communication may be performed by a wireless method. That is, the robot 2 and the control device 1 may be connected by wired communication or wireless communication.

[0015] In the illustrated configuration, the robot 2 is a horizontal articulated robot, that is, a scalar robot.

[0016] As shown in FIGS. 1 to 3, the robot 2 includes a base 21, a first arm 22, a second arm 23, and a third arm 24 which is a work head. The first arm 22, the second arm 23, and the third arm 24 constitute a robot arm 20.

[0017] In addition, the robot 2 includes a drive unit 25 that rotates the first arm 22 with respect to the base 21, a drive unit 26 that rotates the second arm 23 with respect to the first arm 22, a u drive unit 27 that rotates the tip shaft (first shaft) 241 of the third arm 24 with respect to the second arm 23, and a z drive unit 28 that moves the tip shaft 241 in the z-axis direction with respect to the second arm 23.

[0018] As shown in FIGS. 1 and 2, the drive unit 25 is built into the base 21 and includes a motor 251 that generates a driving force, a speed reducer 252 that decelerates the driving force of the motor 251, and a position sensor 253 that detects the rotation angle of the rotation shaft of the motor 251 or the speed reducer 252.

[0019] The drive unit 26 is built into the housing 230 of the second arm 23, and includes a motor 261 that generates a driving force, a speed reducer 262 that reduces the driving force of the motor 261, and a position sensor 263 that detects the rotation angle of the rotating shaft of the motor 261 or the speed reducer 262.

[0020] The u-drive unit 27 is built into the housing 230 of the second arm 23, and includes a motor 271 that generates a driving force and a position sensor 273 that detects the rotation angle of the rotating shaft of the motor 271.

[0021] The z-drive unit 28 is built into the housing 230 of the second arm 23, and includes a motor 281 that generates a driving force and a position sensor 283 that detects the rotation angle of the rotating shaft of the motor 281.

[0022] As the motors 251, 261, 271, and 281, for example, servo motors such as AC servo motors and DC servo motors can be used.

[0023] Also, as the speed reducers 252 and 262, for example, planetary gear type speed reducers, harmonic gear devices, etc. can be used. Also, the position sensors 253, 263, 273, and 283 can be, for example, angle sensors.

[0024] The drive unit 25, the drive unit 26, the u-drive unit 27, and the z-drive unit 28 are each connected to a corresponding motor driver (not shown), and are controlled by the robot control unit 11 of the control device 1 via the motor driver.

[0025] The base 21 is fixed to a floor surface (not shown) by bolts or the like. The first arm 22 is connected to the upper end of the base 21. The first arm 22 is rotatable around a first axis O1 that is perpendicular to the base 21. When the drive unit 25 that rotates the first arm 22 is driven, the first arm 22 rotates in the horizontal plane around the first axis O1 relative to the base 21. In addition, the amount of rotation of the first arm 22 relative to the base 21 can be detected by the position sensor 253.

[0026] Furthermore, a second arm 23 is connected to the tip of the first arm 22. The second arm 23 is rotatable around a second axis O2 that is perpendicular to the first arm 22. The axial direction of the first axis O1 and the axial direction of the second axis O2 are the same. That is, the second axis O2 is parallel to the first axis O1. When the drive unit 26 that rotates the second arm 23 is driven, the second arm 23 rotates in the horizontal plane around the second axis O2 relative to the first arm 22. In addition, a position sensor 263 can detect the drive of the second arm 23 relative to the first arm 22, specifically the amount of rotation. That is, the second axis O2 is the center of the output rotation axis of the reduction gear 262.

[0027] Furthermore, the second arm 23 has a housing 230 having a base portion 231 which is a wall portion, a top plate 232, and four side walls 233 which connect them. Inside this housing 230, that is, on the base portion 231, the drive unit 26, the u drive unit 27, and the z drive unit 28 are arranged in this order from the +y axis side.

[0028] Furthermore, as shown in Figure 3, the base portion 231 is the bottom of the second arm 23 and has a recess 230C in which the u drive unit 27 is positioned. A portion of the recess 230C on the -z axis side is open to the -z axis side, and this open A rotating support member 242 is embedded in the lower part, and a tip shaft 241 is inserted through it.

[0029] Furthermore, a third arm 24 is installed at the tip of the second arm 23. The third arm 24 has a tip shaft 241 and a rotating support member 242 that rotatably supports the tip shaft 241.

[0030] The tip shaft 241 is rotatable around a third axis O3 that is perpendicular to the second arm 23, and is also movable (up and down) in the vertical direction. In other words, the tip shaft 241 is a ball screw spline shaft, and this tip shaft 241 is the very tip of the robot arm 20.

[0031] Furthermore, a ball screw nut 243 and a spline nut 244 are installed along the longitudinal direction of the tip shaft 241, and the tip shaft 241 is supported by these. These ball screw nut 243 and spline nut 244 are positioned spaced apart from the +z axis in this order.

[0032] The ball screw nut 243 has an inner ring 243A and an outer ring 243B that is concentrically arranged on the outer circumference of the inner ring 243A. A number of balls (not shown) are arranged between the inner ring 243A and the outer ring 243B, and the inner ring 243A and the outer ring 243B rotate relative to each other as the balls move.

[0033] Furthermore, the inner ring 243A has a portion exposed from the outer ring 243B, and a belt 284, which will be described later, is wrapped around this exposed portion. The inner ring 243A also has a tip shaft 241 inserted inside it, and as will be described later, it supports the tip shaft 241 so that it can move along the z-axis direction. The outer ring 243B is fixed to the base portion 231.

[0034] The spline nut 244 has an inner ring 244A and an outer ring 244B that is concentrically positioned on the outer circumference of the inner ring 244A. A number of balls (not shown) are positioned between the inner ring 244A and the outer ring 244B, and the inner ring 244A and the outer ring 244B rotate relative to each other as the balls move.

[0035] Furthermore, the inner ring 244A has a portion exposed from the outer ring 244B, and the belt 274, which will be described later, is wrapped around this exposed portion. The inner ring 244A also has the tip shaft 241 inserted inside it and supports the tip shaft 241 so that it can rotate around the z axis, i.e., in the u axis direction. The outer ring 244B is fixed to the recess 230C of the base portion 231, which will be described later.

[0036] Furthermore, a rotational support member 242 is installed on the -z-axis side of the spline nut 244. This rotational support member 242 has an outer cylinder 245 and a rotating body 246 provided inside the outer cylinder 245. The outer cylinder 245 is fixed to the base portion 231 inside the housing 230 of the second arm 23. On the other hand, the rotating body 246 is fixed to the tip shaft 241, but is supported by the outer cylinder 245 so as to be rotatable together with the tip shaft 241 around the z-axis, i.e., in the u-axis direction.

[0037] When the u-drive unit 27, which rotates the tip shaft 241, is driven, the tip shaft 241 rotates in forward and reverse directions around the z-axis, i.e., rotates. In addition, the position sensor 273 allows the amount of rotation of the tip shaft 241 relative to the second arm 23 to be detected.

[0038] Furthermore, when the z-drive unit 28, which moves the tip shaft 241 in the z-axis direction, is driven, the tip shaft 241 moves in the vertical direction, i.e., in the z-axis direction. In addition, the position sensor 283 can detect the amount of z-axis movement of the tip shaft 241 relative to the second arm 23.

[0039] Furthermore, various end effectors are detachably connected to the tip of the tip shaft 241. The end effectors are not particularly limited and include, for example, those for gripping objects to be conveyed, for processing objects, and for inspection. In this embodiment, an end effector 7 is detachably connected.

[0040] In this embodiment, the end effector 7 is not a component of the robot 2, but part or all of the end effector 7 may be a component of the robot 2. Also, in this embodiment, the end effector 7 is not a component of the robot arm 20, but part or all of the end effector 7 may be a component of the robot arm 20.

[0041] Furthermore, in this embodiment, the end effector 7 is detachable from the robot arm 20, but this is not limited to this, and for example, the end effector 7 may be made indestructible from the robot arm 20.

[0042] As shown in Figure 2, the control device 1 comprises a robot control unit 11, a motor control unit 12 (end effector control unit), a display control unit 13, a storage unit 14, and a reception unit 15, and controls the drive of each part of the robot system 100, such as the motors of the robot 2 and the end effector 7.

[0043] Furthermore, the control device 1 is configured to communicate with each other: the robot control unit 11, the motor control unit 12, the display control unit 13, the storage unit 14, and the reception unit 15. In other words, the robot control unit 11, the motor control unit 12, the display control unit 13, the storage unit 14, and the reception unit 15 are connected to each other by wired or wireless communication.

[0044] Furthermore, the control device 1 is connected to the robot 2 and the end effector 7, respectively, by wired or wireless communication.

[0045] The robot control unit 11 controls the driving of the robot 2, that is, the driving of the robot arm 20, etc. The robot control unit 11 is a computer on which programs such as an OS are installed. This robot control unit 11 has, for example, a CPU as a processor, RAM and ROM where programs are stored. Furthermore, the functions of the robot control unit 11 can be realized, for example, by executing various programs using the CPU.

[0046] The motor control unit 12 controls the drive of the motor 72. The motor control unit 12 is a computer on which programs such as an OS are installed. This motor control unit 12 has, for example, a CPU as a processor, RAM and ROM where programs are stored. Furthermore, the functions of the motor control unit 12 can be realized, for example, by executing various programs using the CPU.

[0047] The display control unit 13 has the function of displaying various screens such as windows and characters on a display device (not shown).

[0048] The memory unit 14 has the function of storing various types of information (including data and programs). This memory unit 14 stores control programs and the like. The functions of the memory unit 14 can be realized by so-called external storage devices (not shown), such as ROM. The reception unit 15 has the function of receiving input from an input device (not shown).

[0049] Next, we will describe the interior of the second arm 23. In robot 2, as shown in Figure 3, the housing 230 of the second arm 23 is provided with a u-drive unit 27 for rotating the third arm 24 around the z-axis, a z-drive unit 28 for moving the third arm 24 in the z-axis direction, a belt 274, and a belt 284.

[0050] As shown in Figure 3, the u-drive unit 27 includes a pulley 275 in addition to the motor 271 and position sensor 273 described above. These are arranged from the +z axis side in the order of position sensor 273, motor 271, and pulley 275, and are fixed to the bottom of the recess 230C. The pulley 275 is fixed to the rotation axis of the motor 271, and the rotational force of the motor 271 is transmitted to the pulley 275.

[0051] Furthermore, the pulley 275 is connected by a belt 274 to the inner ring 244A of a spline nut 244 provided on the tip shaft 241. The belt 274 is an endless belt wrapped around the pulley 275 and the inner ring 244A, and has teeth (not shown) on its inner side, i.e., on the side facing the pulley 275 and the inner ring 244A. The teeth of the belt 274 mesh with teeth (not shown) on the exposed portions of the pulley 275 and the inner ring 244A, respectively.

[0052] In such a u-drive unit 27, the rotational force of the motor 271 is transmitted to the belt 274 via the pulley 275, causing the belt 274 to rotate. This rotation of the belt 274 transmits the rotational force to the tip shaft 241 via the spline nut 244. This rotational force is transmitted to the tip shaft 241 via the inner circumference of the inner ring 244A and the spline groove (not shown) of the tip shaft 241, allowing the tip shaft 241 to move in the u-axis direction, i.e., to rotate.

[0053] As shown in Figure 4, the z-drive unit 28 has a pulley 285 in addition to the motor 281 and position sensor 283 mentioned above. These are arranged from the +z axis side in the order of position sensor 283, motor 281, and pulley 285. The pulley 285 is fixed to the rotation axis of the motor 281, and the rotational force of the motor 281 is transmitted to the pulley 285.

[0054] Furthermore, the pulley 285 is connected by a belt 284 to the exposed portion of the inner ring 243A of a ball screw nut 243 provided on the tip shaft 241. The belt 284 is an endless belt wrapped around the pulley 285 and the inner ring 243A, and has teeth (not shown) on its inner side, i.e., on the side facing the pulley 285 and the inner ring 243A. The teeth of the belt 284 mesh with teeth (not shown) on the pulley 285 and the inner ring 243A, respectively.

[0055] In this z-drive unit 28, the rotational force of the motor 281 is transmitted to the belt 284 via the pulley 285, causing the belt 284 to rotate. This rotation of the belt 284 transmits the rotational force to the tip shaft 241 via the inner ring 243A of the ball screw nut 243. The direction of this rotational force is changed by the inner circumference of the inner ring 243A and the ball screw groove of the tip shaft 241, allowing the tip shaft 241 to move in the z-axis direction, i.e., to move up and down.

[0056] Next, the positional relationship between the tip shaft 241, the u-drive unit 27, the z-drive unit 28, and the second axis O2 will be explained. Conventionally, the components were arranged in the following order from the tip side, i.e., the -y-axis side: the member corresponding to the tip shaft 241, the unit corresponding to the z-drive unit 28, the unit corresponding to the u-drive unit 27, and the second axis O2. In other words, the unit corresponding to the u-drive unit 27 and the unit corresponding to the z-drive unit 28 were positioned closer to the tip than the second axis O2. As a result, when viewed as a whole robot arm, the center of gravity tends to be concentrated towards the tip side. Consequently, the inertia for driving the robot arm becomes large, which may lead to problems such as increased power consumption and excessive heat generation of components such as regenerative resistors.

[0057] In contrast, the present invention can solve the above problems by having the following configuration. In robot 2, the tip shaft 241, second axis O2, z drive unit 28, and u drive unit 27 are arranged in that order from the tip side, i.e., the -y axis side. That is, the z drive unit 28 and u drive unit 27 are located on the base side of the second axis O2. To put it another way, at least one (both in this embodiment) of motor 281 and motor 271 is located on the opposite side of the tip shaft 241 from the second axis O2.

[0058] With this configuration, the center of gravity of the second arm 23 can be moved closer to the base end than in the conventional configuration. Therefore, it is possible to suppress excessive inertia when driving the robot arm 20. As a result, it is possible to suppress an increase in power consumption and suppress excessive heat generation in components such as regenerative resistors.

[0059] In this embodiment, the u-drive unit 27 is a unit in which the motor 271 and the position sensor 273 are fixed coaxially. However, the present invention is not limited to this, and at least one of the motor 271 and the position sensor 273 may be arranged in different positions from each other. In this case, the effects of the present invention can be achieved as long as at least the motor 271 is located on the opposite side of the tip shaft 241 with respect to the second axis O2.

[0060] Similarly, in this embodiment, the z-drive unit 28 is a unit in which the motor 281 and the position sensor 283 are coaxially fixed. However, the present invention is not limited to this, and at least one of the motor 281 and the position sensor 283 may be arranged in different positions from each other. In this case, the effects of the present invention can be achieved as long as at least the motor 281 is located on the opposite side of the tip shaft 241 with respect to the second axis O2.

[0061] Thus, the device comprises a base 21, a first arm 22 connected to the base 21 and rotating around a first axis O1, a second arm 23 connected to the first arm 22 and rotating around a second axis O2 parallel to the first axis O1, a tip shaft 241 which is a first shaft connected to the second arm 23 and moving in the axial direction of a third axis O3 parallel to the second axis O2, or rotating around the third axis O3, and a motor 281 provided on the second arm 23 to drive the tip shaft 241 to move in a direction parallel to the third axis O3, or a motor 271 provided on the second arm 23 to drive the tip shaft 241 to rotate around the third axis O3. Furthermore, at least one (both in this embodiment) of the motor 281 and motor 271 is located on the opposite side of the tip shaft 241 from the second axis O2. This allows the center of gravity of the second arm 23 to be moved closer to the base end than in the conventional design. Therefore, it is possible to suppress the inertia from becoming too large when driving the robot arm 20. As a result, the increase in power consumption can be suppressed.

[0062] Furthermore, the motor in robot 2 includes a first motor, motor 281, and a second motor, motor 271. Motor 281 drives the first shaft, the tip shaft 241, to move in the axial direction of the third axis O3, and motor 271 drives the tip shaft 241 to rotate around the third axis O3. This allows the tip shaft 241 to be driven to move in the axial direction of the third axis O3 and to rotate around the third axis O3.

[0063] Furthermore, when D1 is the distance between the second axis O2 and the third axis O3, D2 is the distance between the second axis O2 and the central axis of the motor 281, and D3 is the distance between the central axis of the motor 271 and the central axis of the motor 281, it is preferable that D1, D2, and D3 have the following relationship.

[0064] It is preferable that D1 > D2 is satisfied. This makes the effects of the present invention more pronounced and prevents the length of the second arm 23 from becoming excessively long.

[0065] The ratio D1 / D2 is not particularly limited, but is preferably 1.2 or more and 10.0 or less, and more preferably 2.0 or more and 5.0 or less. This allows the above effects to be more reliably achieved.

[0066] It is preferable that D1 > D3 is satisfied. This makes the effects of the present invention more pronounced and prevents the length of the second arm 23 from becoming excessively long.

[0067] <Second Embodiment> Figure 4 is a partial cross-sectional view showing the inside of a second arm in a second embodiment of a robot system comprising the robot of the present invention.

[0068] The following describes a second embodiment of the robot of the present invention with reference to this figure, but the differences from the first embodiment will be explained below.

[0069] As shown in Figure 4, in robot 2, the components are arranged in the following order from the tip side, i.e., the -y axis side: tip shaft 241, z drive unit 28, second axis O2, and u drive unit 27. That is, the z drive unit 28 is located closer to the tip than the second axis O2, and the u drive unit 27 is located closer to the base than the second axis O2. In other words, the second motor 271 is located on the opposite side of the tip shaft 241 from the second axis O2.

[0070] Thus, in this embodiment, at least the second motor, motor 271, is located on the opposite side of the tip shaft 241 from the second shaft O2. This makes it possible to obtain the effects of the present invention described in the above embodiment, and also minimizes the number of structural changes required when changing from a conventional configuration to the configuration of the present invention.

[0071] Furthermore, D1, D2, and D3 preferably have the following relationship. The ratio D1 / D2 is not particularly limited, but is preferably 1.2 or more and 5.0 or less, and more preferably 2.0 or more and 3.0 or less. This allows the effects of the present invention to be obtained more significantly.

[0072] It is preferable that D1 > D3 is satisfied. This makes the effects of the present invention more pronounced and prevents the length of the second arm 23 from becoming excessively long.

[0073] The ratio D1 / D3 is not particularly limited, but is preferably 1.2 or more and 10.0 or less, and more preferably 2.0 or more and 5.0 or less. This allows the above effects to be more reliably achieved.

[0074] Furthermore, in this embodiment, only the second motor, motor 271, is located on the opposite side of the tip shaft 241 to the second axis O2. However, the invention is not limited to this, and only the first motor, motor 281, may be located on the opposite side of the tip shaft 241 to the second axis O2. Even in this case, the effects of the present invention described in the above embodiment can be obtained, and the number of structural changes required when changing from a conventional configuration to the configuration of the present invention can be minimized.

[0075] <Third Embodiment> Figure 5 is a partial cross-sectional view showing the inside of a second arm in a third embodiment of a robot system comprising the robot of the present invention.

[0076] The following describes a third embodiment of the robot of the present invention with reference to this figure, but the differences from the first embodiment will be explained below.

[0077] As shown in Figure 5, the third arm 24 includes a tip shaft (first shaft) 291, a rotatable support member 292 that rotatably supports the tip shaft 291, a transmission shaft (second shaft) 301, a rotatable support member 302 that rotatably supports the transmission shaft 301, and a connecting member 310 that connects the tip shaft 291 and the transmission shaft 301. In this embodiment, the tip shaft 291 is a ball spline shaft, and the transmission shaft 301 is a ball screw shaft.

[0078] The tip shaft 291 is provided with a spline nut 293. The spline nut 293 has an inner ring 293A and an outer ring 293B that is concentrically arranged on the outer circumference of the inner ring 293A. A number of balls (not shown) are arranged between the inner ring 293A and the outer ring 293B, and the inner ring 293A and the outer ring 293B rotate relative to each other as the balls move.

[0079] Furthermore, the inner ring 293A has a portion exposed from the outer ring 293B, and the belt 274 is wrapped around this exposed portion. In addition, the inner ring 293A has a tip shaft 291 inserted inside it and supports the tip shaft 291 so that it can rotate around the z axis, i.e., in the u axis direction.

[0080] Furthermore, a rotational support member 292 is installed on the -z-axis side of the spline nut 293. This rotational support member 292 has an outer cylinder 294 and a rotating body 295 provided inside the outer cylinder 294. The outer cylinder 294 is fixed to the base portion 231 inside the housing 230 of the second arm 23. On the other hand, the rotating body 295 is fixed to the tip shaft 291, but is supported by the outer cylinder 294 so as to be rotatable together with the tip shaft 291 around the z-axis, i.e., in the u-axis direction.

[0081] When the u-drive unit 27 is driven, the tip shaft 291 rotates in forward and reverse directions around the z-axis, i.e., rotates. In addition, the position sensor 273 allows the amount of rotation of the tip shaft 291 relative to the second arm 23 to be detected.

[0082] Furthermore, a connecting member 310 is attached to the +z-axis end of the tip shaft 291 in a manner that allows it to rotate relative to the tip shaft 291, but prevents it from moving in the vertical direction.

[0083] The transmission shaft 301 has a pulley 304 on the -z axis side. A belt 284 is wrapped around the pulley 304, and the rotational force of the motor 281 is transmitted to the transmission shaft 301 via the belt 284 and the pulley 304, causing the transmission shaft 301 to rotate in both forward and reverse directions.

[0084] Furthermore, the ball screw nut 303 is provided at the +z-axis end of the transmission shaft 301 and is attached to the connecting member 310 in a manner that prevents rotation. Therefore, the ball screw nut 303 moves vertically together with the connecting member 310 and the tip shaft 291 as the transmission shaft 301 rotates due to the drive of the z-drive unit 28. In addition, the position sensor 283 can detect the amount of movement of the tip shaft 291 in the z-axis direction relative to the second arm 23.

[0085] Furthermore, the transmission shaft 301 is positioned on the +y axis side of the tip shaft 291 and extends along the fourth axis O4 which is parallel to the third axis O3. The transmission shaft 301 is rotatably supported by the base portion 231 via a rotating support member 302.

[0086] Thus, in this embodiment, the robot 2 is positioned along a fourth axis O4 that is different from the third axis O3 and parallel to the third axis O3, and has a transmission shaft 301 that transmits the driving force of the first motor, motor 281, to the tip shaft 291. 9 1 can be moved along the axial direction of the fourth axis O4.

[0087] Furthermore, the transmission shaft 301 is positioned towards the tip of the second axis O2. That is, the transmission shaft 301 is located between the second axis O2 and the first shaft, which is the tip shaft 291. This makes it possible to minimize the number of parts that need to be changed when modifying a robot with a configuration such as that shown in Japanese Patent Application Publication No. 2003-285282 to the robot 2 of the present invention.

[0088] Furthermore, when the distance between the third axis O3 and the fourth axis O4 is D4, the ratio D1 / D4 is not particularly limited, but is preferably 1.2 or more and 10.0 or less, and more preferably 2.0 or more and 5.0 or less. This allows the above effects to be more reliably achieved.

[0089] <Fourth Embodiment> Figure 6 is a partial cross-sectional view showing the inside of the second arm of a fourth embodiment of a robot system comprising the robot of the present invention.

[0090] The following describes a fourth embodiment of the robot of the present invention with reference to this figure, but the differences from the third embodiment will be explained below.

[0091] As shown in Figure 6, in this embodiment, the transmission shaft 301 is located on the +y axis side of the second axis O2 and on the -y axis side of the z drive unit 28. In other words, the transmission shaft 301, which is the second shaft, is located on the opposite side of the first shaft, the tip shaft 291, relative to the second axis O2. This allows the position of the center of gravity to be moved further towards the base end than in the third embodiment. Therefore, the effects of the present invention can be exhibited even more effectively.

[0092] In the illustrated configuration, the u-drive unit 27 and the z-drive unit 28 are positioned at different locations in the y-axis direction. However, the present invention is not limited to this configuration, and their positions in the y-axis direction may be the same. In this case, it is preferable that the u-drive unit 27 and the z-drive unit 28 are offset in the x-axis direction. Furthermore, in this case, it is even more preferable that the transmission shaft 301, the u-drive unit 27, and the z-drive unit 28 are positioned at the same location in the y-axis direction and offset in the x-axis direction. This makes it possible to miniaturize the second arm 23.

[0093] Although the robot of the present invention has been described above based on the illustrated embodiment, the present invention is not limited thereto, and the configuration of each part can be replaced with any configuration having a similar function. In addition, any other components may be added.

[0094] Furthermore, although the robot arm has three rotation axes in the above embodiment, the present invention is not limited to this, and the number of rotation axes of the robot arm may be, for example, two, or four or more. In other words, although the number of arms is three in the above embodiment, the present invention is not limited to this, and the number of arms may be, for example, two, or four or more.

[0095] Furthermore, in the above embodiment, the tip shaft 241 is rotatable about a third axis O3 that is vertically aligned with the second arm 23 and is also movable (up and down) in the vertical direction. However, it is not limited to this, and for example, the tip shaft 241 may only be movable (up and down) in the vertical direction. In that case, the u-drive unit 27 may be omitted from the second arm 23, and only the z-drive unit 28 may be mounted on it. [Explanation of Symbols]

[0096] 1…Control device, 2…Robot, 7…End effector, 11…Robot control unit, 12…Motor control unit, 13…Display control unit, 14…Storage unit, 15…Reception unit, 20…Robot arm, 21…Base, 22…First arm, 23…Second arm, 24…Third arm, 25…Drive unit, 26…Drive unit, 27…U-drive unit, 28…Z-drive unit 、7 2…Motor, 100…Robot system, 200…Cable, 230…Housing, 230C…Recess, 231…Base, 232…Top plate, 233…Side wall, 241…Tip shaft (first shaft), 242…Rotating support member, 243…Ball screw nut, 243A…Inner ring, 243B…Outer ring, 244…Spline nut, 244A…Inner ring, 244B…Outer ring, 245…Outer cylinder, 246…Rotating body, 251…Motor, 252…Gear reducer, 253…Position sensor, 261…Motor, 262…Gear reducer, 263…Position sensor, 271…Motor 273...Position sensor, 274...Belt, 275...Pulley, 281...Motor, 283...Position sensor, 284...Belt, 285...Pulley, 291...Tip shaft (first shaft), 292...Rotation support member, 293...Spline nut, 293A...Inner ring, 293B...Outer ring, 294...Outer cylinder, 295...Rotating body, 301...Transmission shaft, 302...Rotation support member, 303...Ball screw nut, 304...Pulley, 310...Connecting member, D1, D2, D3, D4...Distance, O1...First shaft, O2...Second shaft, O3...Third shaft, O4...Fourth shaft

Claims

1. Base and, A first arm connected to the base and rotating around a first axis, A second arm connected to the first arm and rotating around a second axis parallel to the first axis, A first shaft connected to the second arm moves in the axial direction of a third axis parallel to the second axis, and rotates around the third axis, A first motor is provided on the second arm and drives the first shaft to move in the axial direction of the third axis, A second motor is provided on the second arm and drives the first shaft to rotate around the third axis, A connecting member is attached to the first shaft in a manner that allows it to rotate relative to the first shaft, but prevents it from moving in the axial direction of the third shaft, The second arm is provided with a second shaft which is arranged along a fourth axis that is different from the third axis and parallel to the third axis, to which the connecting member is connected, and which has a ball screw that moves the connecting member in the axial direction of the fourth axis, and which rotates when driven by the first motor, thereby transmitting the driving force of the first motor to the first shaft via the connecting member, A robot characterized in that at least one of the first motor and the second motor and the second shaft are located on the opposite side of the second axis from the first shaft.

2. The robot according to claim 1, wherein the first motor and the second motor are located on the opposite side of the second axis from the first shaft.

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