Robot

Abstract

Provided is a robot in which operation accuracy can be improved.　The robot has a foundation, a base-end arm, and a leading-end arm. The leading-end arm has: an arm base; a leading-end shaft part that rotates about a leading-end rotation axis relative to the arm base; a motor that has an output shaft that rotates about a first rotation axis; and a motive power transmission part that transmits the rotation of the output shaft to the leading-end shaft part. The motive power transmission part has a first rotation transmission member disposed on the output shaft, a second rotation transmission member disposed on the leading-end shaft part, an intermediate rotation transmission member that rotates about a second rotation axis, a first annular member that is wrapped around the first rotation transmission member and the intermediate rotation transmission member, and a second annular member that is wrapped around the intermediate rotation transmission member and the second rotation transmission member. In a plan view in a direction along the leading-end rotation axis, the first rotation axis and the second rotation axis are positioned on opposite sides to each other relative to a virtual straight line connecting the leading-end rotation axis and a base-end rotation axis.

Description

Robot

[0001] The present invention relates to a robot.

[0002] The robot described in Patent Document 1 has a lower arm mechanism having a first parallel link structure, an upper arm mechanism having a second parallel link structure, a base portion forming a lower side portion of the first parallel link structure, and a wrist portion forming a distal side portion of the second parallel link structure. Further, the wrist portion has a support member, a servo motor provided on the support member, and a rotating body that is rotationally driven by the servo motor about a vertical axis.

[0003] Japanese Patent Application Laid-Open No. 2015-208814

[0004] However, in such a robot, since the servo motor is disposed eccentrically on one side of the wrist portion, the weight balance of the wrist portion is poor, and there is a risk that the operation accuracy of the robot may be reduced.

[0005] The robot according to an application example of the present invention has a base, a proximal arm connected to the base and rotating about a proximal rotation axis with respect to the base, and a distal arm connected to the proximal arm and rotating about an intermediate rotation axis with respect to the proximal arm. The distal arm has an arm base, a distal shaft portion that rotates about a distal rotation axis that is parallel to the proximal rotation axis and spaced apart from the proximal rotation axis with respect to the arm base, a motor having an output shaft that rotates about a first rotation axis parallel to the distal rotation axis, and a power transmission portion that transmits the rotation of the output shaft to the distal shaft portion. The power transmission portion has a first rotation transmission member disposed on the output shaft, a second rotation transmission member disposed on the distal shaft portion, an intermediate rotation transmission member that rotates about a second rotation axis parallel to the distal rotation axis with respect to the arm base, a first annular member wound around the first rotation transmission member and the intermediate rotation transmission member, and a second annular member wound around the intermediate rotation transmission member and the second rotation transmission member. In a plan view from a direction along the distal rotation axis, the first rotation axis and the second rotation axis are located on opposite sides with respect to a virtual straight line connecting the distal rotation axis and the proximal rotation axis.

[0006] Figure 1 is a perspective view showing a robot system according to the first embodiment. Figure 2 is a cross-sectional view of the first arm. Figure 3 is a cross-sectional view of the base end of the third arm. Figure 4 is a perspective view of the arm base of the third arm. Figure 5 is a cross-sectional view of the tip of the third arm. Figure 6 is a cross-sectional view showing the procedure for attaching the third arm to the second arm. Figure 7 is a cross-sectional view showing the procedure for attaching the third arm to the second arm. Figure 8 is a front view of the fourth arm. Figure 9 is a front view showing the procedure for attaching the fourth arm to the third arm. Figure 10 is a front view showing the procedure for attaching the fourth arm to the third arm. Figure 11 is a partial cross-sectional view showing the fourth arm. Figure 12 is a cross-sectional view of the tip shaft portion arranged on the fourth arm. Figure 13 is a partial cross-sectional view showing the intermediate rotation transmission member arranged on the fourth arm. Figure 14 is a top view showing the arrangement of the rotation shaft of the motor, the rotation shaft of the intermediate rotation transmission member, and the rotation shaft of the tip shaft portion. Figure 15 is a partial cross-sectional view showing the first drive unit. Figure 16 is a side view showing the link mechanism. Figure 17 is a top view of the fourth arm of the robot according to the second embodiment.

[0007] The robot of the present invention will be described in detail below based on the embodiments shown in the attached drawings. For the sake of explanation, each figure shows three mutually orthogonal axes: the X-axis, Y-axis, and Z-axis. The Z-axis is aligned vertically, and the X-axis and Y-axis are aligned horizontally. In the following, the direction aligned with the X-axis will also be referred to as the X-axis direction, the direction aligned with the Y-axis as the Y-axis direction, and the direction aligned with the Z-axis as the Z-axis direction. The side of the Z-axis indicated by the arrow will also be referred to as the upper side, and the opposite side as the lower side.

[0008] Furthermore, in this specification, descriptions such as "orthogonal," "parallel," and "symmetrical" all mean that they are "orthogonal," "parallel," and "symmetrical" to a degree that allows for manufacturing tolerances. Specifically, "orthogonal" means substantially orthogonal, and includes the range in which the angle between two lines or two planes is 80 degrees or more and 100 degrees or less. "Parallel" means substantially parallel, and includes the range in which the angle between two lines or two planes is 0 degrees or more and 10 degrees or less. "Symmetrical" means substantially symmetrical, and includes the range in which, when one of two elements is superimposed on the other, the ratio of the overlapping area to the total area of ​​the other is 90% or more and 100% or less.

[0009] <First Embodiment> Figure 1 is a perspective view showing a robot system according to the first embodiment. Figure 2 is a cross-sectional view of the first arm. Figure 3 is a cross-sectional view of the base end of the third arm. Figure 4 is a perspective view of the arm base of the third arm. Figure 5 is a cross-sectional view of the tip of the third arm. Figures 6 and 7 are cross-sectional views showing the procedure for attaching the third arm to the second arm. Figure 8 is a front view of the fourth arm. Figures 9 and 10 are front views showing the procedure for attaching the fourth arm to the third arm. Figure 11 is a partial cross-sectional view showing the fourth arm. Figure 12 is a cross-sectional view of the tip shaft portion arranged on the fourth arm. Figure 13 is a partial cross-sectional view showing the intermediate rotation transmission member arranged on the fourth arm. Figure 14 is a top view showing the arrangement of the rotation shaft of the motor, the rotation shaft of the intermediate rotation transmission member, and the rotation shaft of the tip shaft portion. Figure 15 is a partial cross-sectional view showing the first drive unit. Figure 16 is a side view showing the link mechanism.

[0010] The robot system 1 shown in Figure 1 comprises a robot 10 and a control device 90 that controls the operation of each part of the robot 10.

[0011] [Control device 90] The control device 90 is connected to the robot 10 by wire or wireless means, enabling the transmission and reception of signals, and controls the operation of each part of the robot 10. The control device 90 is, for example, a computer and includes a processor such as a CPU (Central Processing Unit), a storage unit consisting of volatile memory such as RAM (Random Access Memory), non-volatile memory such as ROM (Read Only Memory), and a communication unit that transmits and receives signals with the robot. Various programs that can be executed by the processor are stored in the storage unit, and the processor controls the operation of each part of the robot 10 by reading and executing the programs stored in the storage unit. In this embodiment, the control device 90 is located outside the robot 10, but the location of the control device 90 is not particularly limited, and it may be located inside the robot 10, for example.

[0012] [Robot 10] Robot 10 is a parallel-link articulated robot and is used in the broad sense of food manufacturing, including, for example, food transport, food plating, food packaging, and food processing. In this case, the workpiece for robot 10 is food or food packaging. However, the application of robot 10 and the type of workpiece are not particularly limited.

[0013] The robot 10 includes a base 110 fixed to the floor or the like, and a robot arm 120 rotatably connected to the base 110. The robot arm 120 is configured such that a first arm 121, a second arm 122, a third arm 123, and a fourth arm 124 are rotatably connected to the base 110 in this order.

[0014] Specifically, the robot arm 120 includes a first arm 121 rotatably connected to the base 110 around a rotation axis A1 along the Z-axis, a second arm 122 rotatably connected to the first arm 121 around a rotation axis A2 along the X-axis, a third arm 123 rotatably connected to the second arm 122 around a rotation axis A3 along the X-axis, and a fourth arm 124 rotatably connected to the third arm 123 around a rotation axis A4 along the X-axis. The fourth arm 124 is also equipped with a tip shaft portion 125 that is rotatable around a rotation axis A5 along the Z-axis. An end effector (not shown) for performing a predetermined operation on a workpiece is detachably attached to the tip shaft portion 125. The end effector may or may not be a component of the robot 10.

[0015] In this way, by configuring the robot arm 120 with four arms 121, 122, 123, and 124, the number of arms can be reduced, thereby lowering the manufacturing cost of the robot 10. As a result, the robot 10 can be provided at a low cost. Next, each of the arms 121 to 124 will be described in order. In this embodiment, the first arm 121, the second arm 122, and the third arm 123 constitute the base arm, and the fourth arm 124 constitutes the tip arm.

[0016] (First Arm 121) First, the first arm 121 will be described. The first arm 121 is located above the base 110 and is rotatable around a rotation axis A1, which serves as the base rotation axis, relative to the base 110. As shown in Figure 2, such a first arm 121 has an arm base 20. A shaft 21 extending in the X-axis direction is rotatably held at the upper end of the arm base 20 via bearings 22 and 23. In the robot 10, this shaft 21 forms the rotation axis A2.

[0017] (Second Arm 122) Next, the second arm 122 will be described. As shown in Figure 1, the second arm 122 is located on the tip side of the first arm 121 and is rotatable around the rotation axis A2 relative to the first arm 121. The second arm 122 also has a rod-shaped arm base 30 that extends in a direction perpendicular to the rotation axis A2. As shown in Figure 2, the base end of the arm base 30 is fixed to the shaft 21. Therefore, the arm base 30 rotates together with the shaft 21 around the rotation axis A2. In particular, the arm base 30 is fixed to the central part of the shaft 21, that is, the part located between the bearing parts 22 and 23. With this configuration, the arm base 30 is supported from both sides, so the rotation of the arm base 30 is stable. Also, as shown in Figure 3, a shaft 31 extending in the X-axis direction is fixed to the tip of the arm base 30. In the robot 10, the rotation axis A3 is formed by this shaft 31. Furthermore, the arm base 30 supports the shaft 31 in its central portion, that is, in the portion excluding both ends. As a result, both ends of the shaft 31 protrude from the arm base 30 in the X-axis direction.

[0018] Furthermore, as shown in Figure 3, the second arm 122 has a first connecting portion 32 and a second connecting portion 33 located at both ends of the shaft 31. The first connecting portion 32 is located on the positive side in the X-axis direction relative to the arm base 30, and the second connecting portion 33 is located on the negative side in the X-axis direction relative to the arm base 30. In other words, the first and second connecting portions 32 and 33 are located on opposite sides of each other in the X-axis direction relative to the arm base 30. The third arm 123 is rotatably connected to the rotation axis A3 of the arm base 30 via these first and second connecting portions 32 and 33.

[0019] Furthermore, the second arm 122 has a third connecting portion 34 positioned on the shaft 31 between the arm base 30 and the second connecting portion 33. The link 132b is rotatably connected to the rotation axis A3 via the third connecting portion 34. The link 132b will be described in detail in the link mechanism 132 described later.

[0020] The first connecting portion 32 has a first bearing portion 321 through which the shaft 31 is inserted, and a first bearing retaining portion 322 that holds the first bearing portion 321, and the first bearing retaining portion 322 is rotatable around the rotation axis A3 relative to the shaft 31. The first bearing retaining portion 322 is connected to the third arm 123. The first bearing portion 321 is a deep groove ball bearing and has an inner ring to which the shaft 31 is fixed, an outer ring to which the first bearing retaining portion 322 is fixed, and a plurality of balls sandwiched between them.

[0021] Similarly, the second connecting portion 33 has a second bearing portion 331 through which the shaft 31 is inserted, and a second bearing retaining portion 332 that holds the second bearing portion 331, and the second bearing retaining portion 332 is rotatable around the rotation axis A3 relative to the shaft 31. The second bearing retaining portion 332 is connected to the third arm 123. The second bearing portion 331 is a deep groove ball bearing and has an inner ring to which the shaft 31 is fixed, an outer ring to which the second bearing retaining portion 332 is fixed, and a plurality of balls sandwiched between them.

[0022] Similarly, the third connecting portion 34 has a third bearing portion 341 through which the shaft 31 is inserted, and a third bearing retaining portion 342 that holds the third bearing portion 341, and the third bearing retaining portion 342 is rotatable around the rotation axis A3 relative to the shaft 31. The link 132b is fixed to the third bearing retaining portion 342. The third bearing portion 341 is composed of two deep groove ball bearings arranged side by side, and each deep groove ball bearing has an inner ring to which the shaft 31 is fixed, an outer ring to which the third bearing retaining portion 342 is fixed, and a plurality of balls sandwiched between them.

[0023] Industrial robots like robot 10 often use cross-roller bearings, which can achieve high rigidity and rotational accuracy. However, due to their structure, cross-roller bearings tend to be large and expensive. In contrast, by using deep groove ball bearings, which are widely used as "rolling bearings," as the first, second, and third bearing sections 321, 331, and 341, the manufacturing cost of robot 10 can be effectively reduced, and robot 10 can be provided at a lower cost. Furthermore, because deep groove ball bearings have a simple structure and are small, it is possible to make robot 10 smaller and lighter.

[0024] However, the configuration of the first and second connecting parts 32 and 33 is not particularly limited, as long as the third arm 123 can be connected to the shaft 31 so as to be rotatable around the rotation axis A3. Similarly, the configuration of the third connecting part 34 is not particularly limited, as long as the link 132b can be connected to the shaft 31 so as to be rotatable around the rotation axis A3. For example, the first, second, and third bearing parts 321, 331, and 341 may be cylindrical roller bearings, angular contact ball bearings, etc.

[0025] Furthermore, as shown in Figure 3, the second arm 122 has a restricting portion 35 that restricts the displacement of the third arm 123 relative to the second arm 122 in the direction along the rotation axis A3. By having the restricting portion 35, the decrease in positional accuracy due to displacement can be suppressed. Also, twisting of each part can be effectively suppressed, and the driving of the robot 10 can be stabilized over the long term. The restricting portion 35 is not particularly limited, but in this embodiment it has a flange 351 that protrudes from the shaft 31, four annular spacers 352, 353, 354, and 355 attached to the shaft 31, and nuts 356 and 357 attached to both ends of the shaft 31, and these are configured to restrict the displacement of the first, second, and third connecting portions 32, 33, and 34.

[0026] Specifically, a flange 351 is positioned between the first connecting portion 32 and the arm base 30, and a spacer 352 is positioned outside the first connecting portion 32, that is, on the positive side in the X-axis direction. Furthermore, a nut 356 is fastened to the shaft 31 on the outside of the first connecting portion 32. Therefore, by tightening the nut 356, the first connecting portion 32 is sandwiched between the flange 351 and the spacer 352, and the position of the first connecting portion 32 is fixed.

[0027] Furthermore, a spacer 353 is positioned between the arm base 30 and the third connecting portion 34, a spacer 354 is positioned between the third connecting portion 34 and the second connecting portion 33, and a spacer 355 is positioned outside the second connecting portion 33, that is, on the negative side in the X-axis direction. In addition, a nut 357 is fastened to the shaft 31 on the outside of the second connecting portion 33. Therefore, by tightening the nut 357, the third connecting portion 34 is sandwiched between the spacers 353 and 354, and the position of the third connecting portion 34 is fixed. Also, the second connecting portion 33 is sandwiched between the spacers 354 and 355, and the position of the second connecting portion 33 is fixed.

[0028] In particular, as in this embodiment, by having a flange 351 that is integrally formed with the shaft 31 and does not shift relative to the shaft 31, the first, second, and third connecting portions 32, 33, and 34 can be positioned with respect to the flange 351. As a result, the positioning accuracy of the first, second, and third connecting portions 32, 33, and 34 is improved.

[0029] (Third Arm 123) Next, the third arm 123 will be described. As shown in Figure 1, the third arm 123 is located on the tip side of the second arm 122 and is rotatable around the rotation axis A3 relative to the second arm 122. The third arm 123 also has an arm base 40 that extends in a direction perpendicular to the rotation axis A2. As shown in Figure 4, the arm base 40 is formed by bending sheet metal such as a steel plate and has a U-shaped semitubular form. Specifically, the arm base 40 has a plate-shaped bottom portion 41 and a pair of side plate portions 42 and 43 that are erected upward from both ends of the bottom portion 41 in the X-axis direction. The side plate portions 42 and 43 are arranged side by side in the X-axis direction, with the side plate portion 42 located on the positive X-axis side relative to the arm base 30 and the side plate portion 43 located on the negative X-axis side. Furthermore, the side plate portion 42 extends further towards the base end than the side plate portion 43, and as shown in Figure 1, the tip of the link 131b is rotatably connected to its base end. The link 131b will be described in the link mechanism 131 described later.

[0030] In particular, in this embodiment, as shown in Figures 4 and 5, the arm base 40 is constructed by screwing together two parts: an L-shaped first base piece 40a having a bottom portion 41 and a side plate portion 42, and an L-shaped second base piece 40b having a bottom portion 41 and a side plate portion 43. Specifically, the arm base 40 is constructed by overlapping the bottom portions 41 of the first and second base pieces 40a and 40b and fastening these portions together with screws, thereby integrally connecting the first and second base pieces 40a and 40b. As a result, the arm base 40 can be easily separated into the first base piece 40a and the second base piece 40b by removing the screws. Consequently, as will be described later, attaching and detaching the third arm 123 to the arm base 30 becomes easier, improving the assembly and maintainability of the robot 10. In particular, by connecting the first and second base pieces 40a and 40b with screws, the first and second base pieces 40a and 40b can be easily connected or separated. However, the method of connecting the first and second base pieces 40a and 40b in a separable manner is not particularly limited.

[0031] Furthermore, as shown in Figures 4 and 5, shaft insertion holes 421 and 431 are formed at the base ends of the pair of side plate portions 42 and 43, arranged side by side in the X-axis direction. The shaft insertion holes 421 and 431 are closed holes. As shown in Figure 3, both ends of the shaft 31 are inserted through the shaft insertion holes 421 and 431. In other words, the first base piece 40a is inserted from the outside of the first connecting portion 32, that is, from the X-axis positive side, into the X-axis positive end of the shaft 31, and the second base piece 40b is inserted from the outside of the second connecting portion 33, that is, from the X-axis negative side, into the X-axis negative end of the shaft 31. Furthermore, around the shaft insertion hole 421, the side plate portion 42 and the first bearing holding portion 322 of the first connecting portion 32 are fixed together with multiple screws, and around the shaft insertion hole 431, the side plate portion 43 and the second bearing holding portion 332 of the second connecting portion 33 are fixed together with multiple screws. As a result, the third arm 123 is connected to the shaft 31 so as to be rotatable around the rotation axis A3.

[0032] Here, the side plate portion 42 is located on the outside relative to the first connection portion 32, that is, on the positive side in the X-axis direction. Therefore, by removing the screws that fix the side plate portion 42 and the first bearing retaining portion 322, the first base piece 40a can be pulled out from the shaft 31. Furthermore, since the screws that fix the side plate portion 42 and the first bearing retaining portion 322 are tightened from the side plate portion 42 side and the screw heads are exposed to the outside, it is easy to attach and detach them. Similarly, the side plate portion 43 is located on the outside relative to the second connection portion 33, that is, on the negative side in the X-axis direction. Therefore, by removing the screws that fix the side plate portion 43 and the second bearing retaining portion 332, the second base piece 40b can be pulled out from the shaft 31. Furthermore, since the screws that fix the side plate portion 43 and the second bearing retaining portion 332 are tightened from the side plate portion 43 side and the screw heads are exposed to the outside, it is easy to attach and detach them. With this configuration, the third arm 123 can be easily attached to and detached from the second arm 122, improving the ease of assembly and maintenance of the robot 10.

[0033] For example, when assembling the third arm 123 to the second arm 122, first, with the first and second base pieces 40a and 40b separated, as shown in Figure 6, one end of the shaft 31 is inserted through the shaft insertion hole 421 of the side plate portion 42, and the side plate portion 42 and the first bearing holding portion 322 are screwed together. This mounts the first base piece 40a onto the shaft 31. Next, as shown in Figure 7, the other end of the shaft 31 is inserted through the shaft insertion hole 431 of the side plate portion 43, and the side plate portion 43 and the second bearing holding portion 332 are screwed together. This mounts the second base piece 40b onto the shaft 31. Next, the bottom portions 41 of the first and second base pieces 40a and 40b are overlapped and screwed together to integrate them. As a result, the third arm 123 is assembled to the second arm 122. To remove the third arm 123 from the second arm 122, simply follow the reverse procedure described above. In this way, the third arm 123 can be attached to and detached from the second arm 122 simply by attaching and detaching screws to the arm base 40. This improves the ease of assembly and maintenance of the robot 10.

[0034] Furthermore, as shown in Figures 4 and 8, the tips of the pair of side plate portions 42 and 43 have notched shaft insertion holes 422 and 432 that are aligned in the X-axis direction relative to each other. The shaft 54 ​​of the fourth arm 124, which will be described later, is inserted through these shaft insertion holes 422 and 432. The shaft insertion holes 422 and 432 are elongated holes that open into the outer edges of the side plate portions 42 and 43, respectively. The shaft insertion holes 422 and 432 extend in directions perpendicular to the extending direction of the third arm 123 and the X-axis direction, respectively, and the ends located on the lower side in the figures open into the outer edges of the side plate portions 42 and 43.

[0035] (Fourth Arm 124) Next, the fourth arm 124 will be described. As shown in Figure 1, the fourth arm 124 is located on the tip side of the third arm 123 and is rotatable around the rotation axis A4, which serves as an intermediate rotation axis, relative to the third arm 123. Also, as shown in Figure 8, the fourth arm 124 has an arm base 50 that extends in a direction perpendicular to the rotation axis A4. The arm base 50 is formed by bending sheet metal such as a steel plate and has a U-shape. The arm base 50 also has a plate-shaped bottom portion 51 that is aligned with the horizontal plane, that is, the X-Y plane, and a pair of side plate portions 52 and 53 that are erected on the upper side from the ends on both sides of the bottom portion 51 in the X-axis direction. The side plate portions 52 and 53 are arranged side by side in the X-axis direction, with the side plate portion 52 located on the positive side in the X-axis direction relative to the side plate portion 53. Furthermore, as shown in Figure 1, the side plate portion 53 is formed to be slightly larger than the side plate portion 52, and the tip of the link 132c is rotatably connected to its upper end. The link 132c will be described later in the link mechanism 132 section.

[0036] In particular, in this embodiment, the arm base 50 is constructed by screwing together two parts: a plate-shaped first base piece 50a with a side plate portion 52, and an L-shaped second base piece 50b with a bottom portion 51 and a side plate portion 53. Specifically, the first and second base pieces 50a and 50b are overlapped at the side plate portion 52, and the overlapped portion is fastened with screws to form the arm base 50 in which the first and second base pieces 50a and 50b are integrated. As a result, the arm base 50 can be easily separated into the first base piece 50a and the second base piece 50b by removing the screws. With this configuration, it is easy to attach and detach parts to the bottom portion 51, improving the assembly and maintainability of the robot 10. However, the configuration of the arm base 50 is not particularly limited, and for example, the bottom portion 51 and the side plate portions 52 and 53 may be integrally formed from a single sheet of metal.

[0037] Furthermore, the fourth arm 124 has a connecting portion 59 that connects the side plate portions 52 and 53. The connecting portion 59 is a U-shaped plate member formed by bending sheet metal such as steel plate, and both ends are screw-fastened to the side plate portions 52 and 53. Thus, the connecting portion 59 has the function of a reinforcing portion that reinforces the arm base 50 and the function of a support portion for supporting the drive unit 60, which will be described later.

[0038] As shown in Figure 8, shaft insertion holes 521 and 531 are formed at the upper ends of the side plate portions 52 and 53, arranged side by side in the X-axis direction. The shaft insertion holes 521 and 531 are elongated notches that extend in the Y-axis direction, with the end on the negative Y-axis side opening into the outer edge of the side plate portions 52 and 53. A shaft 54 ​​extending along the X-axis direction is inserted through these shaft insertion holes 521 and 531. The shaft 54 ​​is rotatably held in the side plate portions 52 and 53 via a pair of shaft holding portions 55 and 56. In the robot 10, this shaft 54 ​​forms the rotation axis A4. However, the shaft insertion holes 521 and 531 are not particularly limited and may be, for example, closed holes.

[0039] The shaft holder portion 55 has a bearing portion 551 through which the shaft 54 ​​is inserted, and a bearing holder portion 552 that holds the bearing portion 551, and the bearing holder portion 552 is rotatable around the rotation axis A4 relative to the shaft 54. The shaft holder portion 55 is screw-fastened to the side plate portion 52 at the bearing holder portion 552. The bearing portion 551 is a deep groove ball bearing and has an inner ring to which the shaft 54 ​​is fixed, an outer ring to which the bearing holder portion 552 is fixed, and a plurality of balls sandwiched between them.

[0040] Similarly, the shaft holder 56 has a bearing portion 561 through which the shaft 54 ​​is inserted, and a bearing holder 562 that holds the bearing portion 561, and the bearing holder 562 is rotatable around the rotation axis A4 relative to the shaft 54. The shaft holder 56 is screw-fastened to the side plate portion 53 at the bearing holder 562. The bearing portion 561 is a deep groove ball bearing and has an inner ring to which the shaft 54 ​​is fixed, an outer ring to which the bearing holder 562 is fixed, and a plurality of balls sandwiched between them.

[0041] In this way, by using deep groove ball bearings as bearing sections 551 and 561, the manufacturing cost of the robot 10 can be effectively reduced, and the robot 10 can be provided at a lower cost. Furthermore, because deep groove ball bearings have a simple structure and are compact, it is possible to make the robot 10 smaller and lighter. However, the configuration of the shaft holding sections 55 and 56 is not particularly limited as long as the shaft 54 ​​can be rotatably held by the side plate sections 52 and 53. For example, the bearing sections 551 and 561 may be cylindrical roller bearings, angular contact ball bearings, etc.

[0042] Furthermore, the shaft holding portion 55 is located inside the side plate portion 52, that is, on the negative side in the X-axis direction, and the shaft holding portion 56 is located inside the side plate portion 53, that is, on the positive side in the X-axis direction. In other words, the shaft holding portions 55 and 56 are located between the side plate portions 52 and 53. Therefore, it is possible to suppress the protrusion of the shaft holding portions 55 and 56 outside the arm base 50, and the fourth arm 124 can be made smaller. In addition, the screws that fix the side plate portion 52 and the bearing holding portion 552 are tightened from the side plate portion 52 side, and the screw heads are exposed on the outside of the arm base 50. Similarly, the screws that fix the side plate portion 53 and the bearing holding portion 562 are tightened from the side plate portion 53 side, and the screw heads are exposed on the outside of the arm base 50. Therefore, these screws can be easily attached and detached.

[0043] Furthermore, as shown in Figure 8, the fourth arm 124 has a pair of mounting portions 57 and 58 arranged on the shaft 54. One mounting portion 57 is located between the shaft holding portions 55 and 56, and the other mounting portion 58 is located outside the shaft holding portion 56, that is, on the negative side in the X-axis direction. In other words, the shaft 54 ​​has the shaft holding portion 55, mounting portion 57, shaft holding portion 56, and mounting portion 58 arranged in that order from the positive side in the X-axis direction, with the shaft holding portions 55 and 56 and the mounting portions 57 and 58 arranged alternately. However, the arrangement of the shaft holding portions 55 and 56 and the mounting portions 57 and 58 is not particularly limited.

[0044] The mounting portions 57 and 58 are each in the form of a disk-shaped flange that protrudes radially from the outer periphery of the shaft 54. Also, the mounting portions 57 and 58 are each formed separately from the shaft 54 and are fixed to the shaft 54 by means such as screwing. And the shaft 54 is detachably connected to the third arm 123 via these mounting portions 57 and 58. Specifically, around the shaft 54, the mounting portion 57 is fixed to the side plate portion 42 by a plurality of screws, and around the shaft 54, the mounting portion 58 is fixed to the side plate portion 43 by a plurality of screws. By making the mounting portions 57 and 58 in the form of flanges, the structure of the mounting portions 57 and 58 becomes simple, and it becomes easier to fix them to the third arm 123 around the shaft 54. Also, by fixing the mounting portions 57 and 58 and the third arm 123 by screwing, they can be easily attached and detached.

[0045] Thus, by forming the mounting portions 57 and 58 separately from the shaft 54, it becomes easy to form them. Also, the degree of freedom in the shape and material of the shaft 54 and the mounting portions 57 and 58 increases. However, it is not limited to this. For example, at least one of the mounting portions 57 and 58 may be integrally formed with the shaft 54. By integrally forming at least one of the mounting portions 57 and 58 with the shaft 54, they can also be easily formed. Also, since the operation of fixing at least one of the mounting portions 57 and 58 to the shaft 54 becomes unnecessary, the assembly of the robot 10 becomes easier by that much. Also, since at least one of the mounting portions 57 and 58 does not shift with respect to the shaft 54, the driving of the robot 10 is stable in the long term. In the present embodiment, it is preferable that the mounting portion 58 is not integrally formed with the shaft 54 and only the mounting portion 57 is integrally formed with the shaft 54 so that the operation of inserting the bearing portion 561 into the shaft 54 is easy.

[0046] The procedure for attaching the fourth arm 124 to the third arm 123 will now be explained. First, as shown in Figure 9, the shaft 54, aligned with the X-axis direction, is inserted into the pair of shaft insertion holes 422 and 432 formed at the tip of the third arm 123 from its radial direction V (direction perpendicular to the X-axis). Then, as shown in Figure 10, the outer surface of the shaft 54 ​​is abutted against the bottom of the shaft insertion holes 422 and 432. This positions the shaft 54 ​​relative to the third arm 123, allowing the rotation axis A4 to be positioned correctly. Next, while maintaining this state, the mounting parts 57 and 58 are screwed together to fix the arm base 40. That is, the mounting part 57 is screwed to the side plate part 42, and the mounting part 58 is screwed to the side plate part 43. As a result, the fourth arm 124 is attached to the third arm 123. To remove the fourth arm 124 from the third arm 123, the reverse procedure described above is followed. In this way, the fourth arm 124 can be attached to and detached from the third arm 123 simply by attaching and detaching screws to the arm base 40. This improves the ease of assembly and maintenance of the robot 10. Furthermore, since only the fourth arm 124 can be removed, the maintainability of the fourth arm 124 is also improved.

[0047] Here, as shown in FIG. 10, the mounting portion 57 is located outside the side plate portion 42, that is, on the plus side in the X-axis direction. And the screw for fixing the mounting portion 57 and the side plate portion 42 is tightened from the side plate portion 42 side. On the outside of the side plate portion 42, that is, on the plus side in the X-axis direction, the shaft holding portion 55 is provided close, and it is difficult to secure a space for screwing. On the other hand, a wider space than the outside is secured inside the side plate portion 42. Therefore, as in the present embodiment, by tightening the screw from the side plate portion 42 side, it becomes easy to secure a space for screwing, and the work can be performed smoothly. On the other hand, the mounting portion 58 is located inside the side plate portion 43, that is, on the plus side in the X-axis direction. And the screw for fixing the mounting portion 58 and the side plate portion 43 is tightened from the side plate portion 43 side. Therefore, the head of the screw is exposed to the outside, and the attachment and detachment of the screw become easy. According to such a configuration, the attachment and detachment of the fourth arm 124 to and from the third arm 123 become easy, and the assemblability and maintainability of the robot 10 are enhanced.

[0048] Further, as described above, since the mounting portion 57 is disposed between the shaft holding portions 55 and 56, the shaft 54 is fixed to the side plate portion 42 via the mounting portion 57 at the portion between the shaft holding portions 55 and 56. According to such a configuration, since the central portion of the shaft 54 is supported by the third arm 123, the shaft 54 is difficult to bend. Therefore, the rotation axis A4 is difficult to wobble, and the rotation of the fourth arm 124 is stabilized.

[0049] Furthermore, as shown in Figure 8, the fourth arm 124 has a restricting portion 500 that restricts the displacement of the fourth arm 124 relative to the third arm 123 in the direction along the rotation axis A4. By having the restricting portion 500, the decrease in positional accuracy due to displacement can be suppressed. Also, twisting of each part can be effectively suppressed, and the driving of the robot 10 can be stabilized over the long term. The restricting portion 500 is not particularly limited, but in this embodiment it has two flanges 501 and 502 that protrude from the shaft 54, five annular spacers 503, 504, 505, 506 and 507 attached to the shaft 54, and nuts 508 and 509 attached to both ends of the shaft 54, and these are configured to restrict the displacement of the shaft holding portions 55 and 56 and the mounting portions 57 and 58.

[0050] Specifically, a flange 501 is located inside the side plate portion 42, and a spacer 505 is located between the side plate portion 42 and the flange 501. In addition, a spacer 504 is located between the shaft holding portion 55 and the mounting portion 57, and a spacer 503 is located outside the shaft holding portion 55. A nut 508 is fastened to the shaft 54 ​​from the outside of the spacer 503. Therefore, by tightening the nut 508, the shaft holding portion 55 and the mounting portion 57 are sandwiched between the flange 501 and the spacer 503, and their positions are fixed.

[0051] Furthermore, a flange 502 is located inside the shaft holding portion 56, and a spacer 506 is located between the shaft holding portion 56 and the mounting portion 58. Also, a spacer 507 is located outside the side plate portion 43, and a nut 509 is fastened to the shaft 54 ​​from the outside of the spacer 507. Therefore, by tightening the nut 509, the shaft holding portion 56 and the mounting portion 58 are sandwiched between the flange 502 and the spacer 507, and their positions are fixed.

[0052] In particular, as in this embodiment, by having flanges 501 and 502 that are integrally formed with the shaft 54 ​​and do not shift relative to the shaft 54, the shaft holding portion 55 and the mounting portion 57 can be positioned with respect to flange 501, and the shaft holding portion 56 and the mounting portion 58 can be positioned with respect to flange 502. As a result, the positioning accuracy of the shaft holding portions 55 and 56 and the mounting portions 57 and 58 is improved.

[0053] As shown in Figures 9 and 10, when attaching the fourth arm 124 to the third arm 123, the spacers 503, 507 and nuts 508, 509 located at both ends of the shaft 54 ​​should be removed first. After attaching the fourth arm 124 to the third arm 123, the spacers 503, 507 and nuts 508, 509 should be reattached to the shaft 54. Alternatively, instead of removing the spacers 503, 507 and nuts 508, 509 from the shaft 54, the nuts 508, 509 may be loosened sufficiently.

[0054] Furthermore, as shown in Figure 11, the fourth arm 124 has the aforementioned tip shaft portion 125 and a drive unit 60 for rotating the tip shaft portion 125 around the rotation axis A5. The drive unit 60 also has a motor 61 having an output shaft 611 and a power transmission unit 62 that transmits the rotation of the output shaft 611 to the tip shaft portion 125.

[0055] The tip shaft portion 125 is held so as to be rotatable around a rotation axis A5, which serves as the tip rotation axis along the Z-axis relative to the bottom portion 51. The rotation axis A5 is parallel to the rotation axis A1 of the first arm 121 and is spaced apart from the rotation axis A1 in the Y-axis direction. In other words, the rotation axes A1 and A5 are spaced apart from each other, and the line segment connecting the rotation axes A1 and A5 is parallel to the Y-axis. Furthermore, as shown in Figure 12, the tip shaft portion 125 is hollow and has through holes 125a that penetrate both end faces, i.e., the top and bottom surfaces. With this configuration, for example, wiring and piping connected to the end effector can be routed through the through holes 125a. Therefore, the exposure of wiring and piping around the end effector can be reduced, and the wiring and piping are less likely to get in the way of work.

[0056] The motor 61 is, for example, a servo motor, particularly a three-phase motor driven by three-phase AC, and is fixed to the connecting part 59 via a support part 69. The output shaft 611 of the motor 61 rotates around a rotation axis B1, which is a first rotation axis along the Z axis. The rotation axis B1 is parallel to the rotation axis A1 and is spaced apart from the rotation axis A1.

[0057] The power transmission unit 62 is a reduction gear and includes an input-side rotation transmission member 621 as a first rotation transmission member, an output-side rotation transmission member 622 as a second rotation transmission member, an intermediate rotation transmission member 623, a first annular member 624 wrapped around the input-side rotation transmission member 621 and the intermediate rotation transmission member 623, and a second annular member 625 wrapped around the intermediate rotation transmission member 623 and the output-side rotation transmission member 622.

[0058] The input-side rotation transmission member 621 is positioned and fixed to the output shaft 611 and rotates together with the output shaft 611 around the rotation axis B1. On the other hand, the output-side rotation transmission member 622 is positioned and fixed to the tip shaft portion 125 and rotates together with the tip shaft portion 125 around the rotation axis A5. The intermediate rotation transmission member 623 is held via a holding portion 68 so as to be rotatable around the rotation axis B2, which is a second rotation axis along the Z axis relative to the bottom portion 51. Note that the rotation axis B2 is parallel to the rotation axis A1 and is separated from rotation axes A1 and B1. In other words, rotation axes A5, B1, and B2 are parallel to each other and are separated from each other.

[0059] As shown in Figure 13, the retaining portion 68 has a bearing portion 681 and a bearing retaining portion 682 that holds the bearing portion 681. The retaining portion 68 is screw-fastened to the bottom portion 51 at the bearing retaining portion 682. The bearing portion 681 is a deep groove ball bearing and has an inner ring to which the intermediate rotation transmission member 623 is fixed, an outer ring to which the bearing retaining portion 682 is fixed, and a plurality of balls sandwiched between them. In this way, by using a deep groove ball bearing as the bearing portion 681, the manufacturing cost of the robot 10 can be effectively reduced, and the robot 10 can be provided at a lower cost. Furthermore, because the deep groove ball bearing has a simple structure and is small, it is possible to make the robot 10 smaller and lighter. However, the configuration of the retaining portion 68 is not particularly limited as long as the intermediate rotation transmission member 623 can be rotatably held to the bottom portion 51. For example, the bearing portion 681 may be a cylindrical roller bearing, an angular contact ball bearing, etc. Alternatively, for example, the intermediate rotation transmission member 623 may be rotatably held on the support portion 69 via a holding portion 68. Alternatively, the intermediate rotation transmission member 623 may be rotatably held on both the bottom portion 51 and the support portion 69 via a pair of holding portions 68.

[0060] As shown in Figure 13, the intermediate rotational transmission member 623 has a third rotational transmission member 623a and a fourth rotational transmission member 623b that are aligned in the Z-axis direction and arranged concentrically with respect to each other. The third rotational transmission member 623a has a larger diameter, i.e., a larger outer diameter, than the input-side rotational transmission member 621. The third rotational transmission member 623a is also positioned at the same height as the input-side rotational transmission member 621. The first annular member 624 is wrapped around the third rotational transmission member 623a and the input-side rotational transmission member 621. The input-side rotational transmission member 621, the third rotational transmission member 623a, and the first annular member 624 constitute the first stage reduction mechanism.

[0061] On the other hand, the fourth rotational transmission member 623b has a smaller diameter, that is, a smaller outer diameter, than the third rotational transmission member 623a and the output-side rotational transmission member 622. Also, the fourth rotational transmission member 623b is positioned at the same height as the output-side rotational transmission member 622. The second annular member 625 is wrapped around the fourth rotational transmission member 623b and the output-side rotational transmission member 622. These fourth rotational transmission member 623b, output-side rotational transmission member 622, and second annular member 625 constitute the second-stage reduction mechanism.

[0062] In this configuration, the rotation of the output shaft 611 is transmitted to the third rotation transmission member 623a via the input-side rotation transmission member 621 and the first annular member 624, causing the intermediate rotation transmission member 623 to rotate around the rotation axis B2. Furthermore, the rotation of the intermediate rotation transmission member 623 is transmitted to the output-side rotation transmission member 622 via the fourth rotation transmission member 623b, causing the output-side rotation transmission member 622 to rotate together with the tip shaft portion 125 around the rotation axis A5. In this way, the power transmission unit 62 is equipped with a total of two reduction mechanisms, which reduces the rotation of the output shaft 611 in two stages, allowing the tip shaft portion 125 to be rotated with a larger torque. In addition, because the reduction ratio by the power transmission unit 62 is large, a high-speed motor 61 can be used. High-speed motors tend to have smaller drive currents and be smaller, so the motor 61 can be made smaller. As a result, the tip weight of the robot arm 120 can be reduced, and vibrations of the robot arm 120 can be effectively suppressed.

[0063] However, the configuration of the power transmission unit 62 is not particularly limited as long as it can transmit the rotation of the output shaft 611 to the tip shaft 125. For example, the power transmission unit 62 does not have to be a reduction gear, and the rotation of the output shaft 611 may be transmitted to the tip shaft 125 at its original speed, or the rotation of the output shaft 611 may be accelerated before being transmitted to the tip shaft 125.

[0064] The combination of each rotational transmission member 621, 622, 623 and each annular member 624, 625 is not particularly limited and can include, for example, a pulley / belt, a sprocket / chain, a wheel / wire, etc., but in this embodiment a pulley / belt is used. With this configuration, since grease, oil, etc. are not used in the power transmission section 62, there is no risk of grease, oil, etc. being scattered onto the workpiece. For this reason, the robot 10 can be suitably used in food manufacturing.

[0065] Furthermore, as shown in Figure 14, in a plan view from the direction along the rotation axis A5 (Z axis), the rotation axis A5 is arranged side by side with the rotation axis A1 in the Y axis direction. Also, the rotation axis B1 of the output shaft 611 and the rotation axis B2 of the intermediate rotation transmission member 623 are located on opposite sides of each other with respect to the virtual straight line LL connecting the rotation axis A5 and the rotation axis A1. In this embodiment, the rotation axis B2 is located on the positive X axis side of the virtual straight line LL, and the rotation axis B1 is located on the negative X axis side. By arranging in this way, the tip shaft portion 125, the motor 61, and the power transmission portion 62 can be balanced on the fourth arm 124, and the weight difference between the portion on the positive X axis side of the virtual straight line LL and the portion on the negative X axis side of the virtual straight line LL can be kept small. As a result, twisting of the robot arm 120 during driving can be effectively suppressed, and the settability of the robot 10, that is, the accuracy of its operation, is improved. As a result, the cycle time of the operation can be shortened, and productivity is improved.

[0066] Furthermore, in a plan view from a direction along the rotation axis A5 (Z axis), rotation axes B1 and B2 are located between rotation axis A5 and rotation axis A1 in the Y axis direction, respectively. In other words, rotation axes B1 and B2 are located closer to rotation axis A1 than to rotation axis A5. With this configuration, the center of gravity of the fourth arm 124 can be shifted towards rotation axis A1, and the inertia of the robot arm 120 around rotation axis A1 is reduced. As a result, the load torque of the robot arm 120 is reduced, and the settlingability of the robot 10 is improved. However, this is not limited to this, and for example, at least one of rotation axes B1 and B2 does not have to be between rotation axis A5 and rotation axis A1.

[0067] Furthermore, in a plan view from a direction along the rotation axis A5 (Z axis), the rotation axis A4 is located between the rotation axis A5 and the rotation axis A1. The rotation axes B1 and B2 are located between the rotation axis A5 and the rotation axis A4 in the Y axis direction. With this configuration, the motor 61 and the intermediate rotation transmission member 623 are not too far from the rotation axis A5. Therefore, the tip shaft portion 125, the motor 61 and the intermediate rotation transmission member 623 can be arranged compactly, and the fourth arm 124 can be miniaturized. However, this is not limited to this, and for example, at least one of the rotation axes B1 and B2 does not have to be between the rotation axis A5 and the rotation axis A4.

[0068] In particular, in this embodiment, the rotating shafts B1 and B2 are positioned biased toward the rotating shaft A4 side than the rotating shaft A5. That is, in the Y-axis direction, the distance between rotating shaft B1 and rotating shaft A4 is shorter than the distance between rotating shaft B1 and rotating shaft A5, and the distance between rotating shaft B2 and rotating shaft A4 is shorter than the distance between rotating shaft B2 and rotating shaft A5. With this configuration, the rotating shaft A5 and the rotating shafts B1 and B2 are appropriately separated, making it easier to increase the outer diameter of the output side rotation transmission member 622 and the third rotation transmission member 623a. As a result, the power transmission section 62 can be made into a speed reducer with a larger reduction ratio.

[0069] Furthermore, in a plan view from a direction along the rotation axis A5 (Z axis), the rotation axis B2 is located between the rotation axis A5 and the rotation axis B1 in the Y-axis direction. In other words, in the Y-axis direction, the distance between the rotation axis B2 and the rotation axis A5 is shorter than the distance between the rotation axis B1 and the rotation axis A5. With this configuration, the intermediate rotation transmission member 623, which tends to have a larger plan view shape than the motor 61, is less likely to protrude from the arm base 50. As a result, contact between the intermediate rotation transmission member 623 and other parts is suppressed, and the driving of the robot 10 becomes stable. However, this is not limited to this, and the rotation axis B2 does not have to be located between the rotation axis A5 and the rotation axis B1.

[0070] Furthermore, in a plan view from a direction along the rotation axis A5 (Z axis), the upper side of the through hole 125a formed in the tip shaft portion 125, i.e., the base end side opening, does not overlap with the power transmission portion 62. In other words, when viewed from above (the positive side in the Z axis direction), the upper opening of the through hole 125a is exposed from the motor 61 and the input-side rotation transmission member 621, output-side rotation transmission member 622, intermediate rotation transmission member 623, first annular member 624, and second annular member 625 that constitute the power transmission portion 62. With this configuration, wiring and piping to the through hole 125a are easily routed. However, the configuration is not limited to this, and at least a part of the upper opening of the through hole 125a may overlap with the motor 61 or the power transmission portion 62.

[0071] The above describes each of the arms 121 to 124.

[0072] The robot 10 further includes, as shown in Figure 1, a first drive unit 140 for rotating the first arm 121 around a rotation axis A1 relative to the base 110, a second drive unit 150 for rotating the second arm 122 around a rotation axis A2 relative to the first arm 121, and a third drive unit 160 for rotating the third arm 123 around a rotation axis A3 relative to the second arm 122. The robot 10 also includes a link mechanism 131 for transmitting power output by the third drive unit 160 to the third arm 123, and a link mechanism 132 for maintaining the fourth arm 124 in a constant position regardless of the positions of the second arm 122 and the third arm 123. The "constant position" refers to the position in which the rotation axis A5 is aligned with the Z-axis, as shown in Figure 1.

[0073] As shown in Figure 15, the first drive unit 140 is located inside the base 110. This first drive unit 140 includes a motor 141 having an output shaft 141a that rotates around the Z axis, and a power transmission unit 142 that transmits the rotation of the motor 141 to the first arm 121.

[0074] The motor 141 is, for example, a servo motor, particularly a three-phase motor driven by three-phase AC, and is fixed to the base 110.

[0075] The power transmission unit 142 is a reduction gear and includes an input-side rotational transmission member 142a fixed to the output shaft 141a, an output-side rotational transmission member 142b fixed to the first arm 121 and having a larger diameter than the input-side rotational transmission member 142a, and an annular member 142c wrapped around the input-side rotational transmission member 142a and the output-side rotational transmission member 142b. The combination of input and output-side rotational transmission members 142a, 142b and the annular member 142c is not particularly limited and can include, for example, a pulley / belt, a sprocket / chain, a wheel / wire, etc., but in this embodiment a pulley / belt is used.

[0076] In this configuration, the rotation of the output shaft 141a is transmitted to the output-side rotation transmission member 142b via the input-side rotation transmission member 142a and the annular member 142c, causing the output-side rotation transmission member 142b and the first arm 121 to rotate integrally around the rotation axis A1. By using a reduction gear as the power transmission unit 142 in this way, the rotation of the output shaft 141a can be reduced, allowing the first arm 121 to rotate with a sufficiently large torque.

[0077] The first drive unit 140 has been described above, but the configuration of the first drive unit 140 is not particularly limited. For example, the power transmission unit 142 may be a gear device such as a planetary gear or a harmonic drive gear. Also, for example, in this embodiment, the power transmission unit 142 is configured as a single-stage reduction gear, but it may be configured as a reduction gear with two or more stages. To briefly explain an example of a two-stage reduction gear, for example, an intermediate rotation transmission member having a first rotation transmission member with a larger diameter than the input-side rotation transmission member 142a and a second rotation transmission member with a smaller diameter than the output-side rotation transmission member 142b may be rotatably arranged around the Z axis between the input-side rotation transmission member 142a and the output-side rotation transmission member 142b, and an annular member may be wrapped around the input-side rotation transmission member 142a and the first rotation transmission member to form the first reduction gear, and an annular member may be wrapped around the second rotation transmission member and the output-side rotation transmission member 142b to form the second reduction gear, thereby creating a two-stage reduction gear. Similarly, two or more intermediate rotational transmission members may be arranged to create a reduction gear with three or more stages.

[0078] As shown in Figure 2, the second drive unit 150 and the third drive unit 160 are each located within the first arm 121. The second drive unit 150 and the third drive unit 160 have the same configuration as the first drive unit 140 described above.

[0079] The second drive unit 150 includes a motor 151 having an output shaft 151a that rotates around the X axis, and a power transmission unit 152 that transmits the rotation of the motor 151 to the second arm 122. The motor 151 is, for example, a servo motor, particularly a three-phase motor driven by three-phase alternating current, and is fixed to the arm base 20.

[0080] The power transmission unit 152 is a reduction gear and includes an input-side rotational transmission member 152a fixed to the output shaft 151a, an output-side rotational transmission member 152b fixed to the shaft 21 and having a larger diameter than the input-side rotational transmission member 152a, and an annular member 152c wrapped around the input-side rotational transmission member 152a and the output-side rotational transmission member 152b. The combination of input and output-side rotational transmission members 152a, 152b and the annular member 152c is not particularly limited and can include, for example, a pulley / belt, a sprocket / chain, a wheel / wire, etc., but in this embodiment a pulley / belt is used.

[0081] In this configuration, the rotation of the output shaft 151a is transmitted to the output-side rotation transmission member 152b via the input-side rotation transmission member 152a and the annular member 152c, causing the output-side rotation transmission member 152b and the shaft 21 to rotate integrally around the rotation axis A2. As a result, the second arm 122, which is fixed to the shaft 21, rotates around the rotation axis A2 relative to the first arm 121. In this way, by using a reduction gear as the power transmission unit 152, the rotation of the output shaft 151a can be reduced, allowing the second arm 122 to rotate with a sufficiently large torque.

[0082] The second drive unit 150 has been described above, but the configuration of the second drive unit 150 is not particularly limited. For example, the power transmission unit 152 may be a gear system such as a planetary gear or a harmonic drive gear. Also, for example, in this embodiment the power transmission unit 152 is configured as a single-stage reduction gear, but like the first drive unit 140 described above, it may be configured as a reduction gear with two or more stages.

[0083] As shown in Figure 2, the third drive unit 160 includes a motor 161 having an output shaft 161a that rotates around the X axis, and a power transmission unit 162 that transmits the rotation of the motor 161 to the third arm 123 via a link mechanism 131. The motor 161 is, for example, a servo motor, particularly a three-phase motor driven by three-phase alternating current, and is fixed to the arm base 20.

[0084] The power transmission unit 162 is a reduction gear and includes an input-side rotational transmission member 162a fixed to the output shaft 161a, an output-side rotational transmission member 162b rotatably held on the shaft 21 via a bearing portion 163 and having a larger diameter than the input-side rotational transmission member 162a, and an annular member 162c wrapped around the input-side rotational transmission member 162a and the output-side rotational transmission member 162b. The combination of input and output-side rotational transmission members 162a, 162b / annular member 162c is not particularly limited and can include, for example, a pulley / belt, a sprocket / chain, a wheel / wire, etc., but in this embodiment a pulley / belt is used.

[0085] In this configuration, the rotation of the output shaft 161a is transmitted to the output-side rotation transmission member 162b via the input-side rotation transmission member 162a and the annular member 162c, causing the output-side rotation transmission member 162b to rotate around the rotation axis A2 relative to the shaft 21. This rotation of the output-side rotation transmission member 162b is then transmitted to the third arm 123 via the link mechanism 131, causing the third arm 123 to rotate around the rotation axis A3 relative to the second arm 122. By using a reduction gear as the power transmission unit 162 in this way, the rotation of the output shaft 161a can be reduced, allowing the third arm 123 to rotate with a sufficiently large torque.

[0086] The third drive unit 160 has been described above, but the configuration of the third drive unit 160 is not particularly limited. For example, the power transmission unit 162 may be a gear system such as a planetary gear or a harmonic drive gear. Also, for example, in this embodiment the power transmission unit 162 is configured as a single-stage reduction gear, but like the first drive unit 140 described above, it may be configured as a reduction gear with two or more stages.

[0087] The link mechanism 131 for transmitting the rotation of the output-side rotation transmission member 162b to the third arm 123 includes, as shown in Figure 16, a link 131a, a link 131b, and pivots 131c and 131d.

[0088] Link 131a is plate-shaped with the X-axis as its normal and extends in a direction perpendicular to the rotation axis A2. At its base end, link 131a is fixed to the output side rotation transmission member 162b of the power transmission unit 162. Link 131b is rod-shaped and extends in a direction perpendicular to the rotation axis A2, and is arranged parallel to the second arm 122. At its base end, link 131b is rotatably connected to the tip of link 131a via pivot 131c around an axis J1 parallel to the rotation axis A2. Note that axis J1 is separated from the rotation axis A2. At its tip, link 131b is rotatably connected to the base end of the third arm 123 via pivot 131d around an axis J2 parallel to the rotation axis A3. Note that axis J2 is separated from the rotation axis A3.

[0089] In such a link mechanism 131, a parallelogram Q1 is formed in a plan view from the X-axis direction, with the rotation axes A2 and A3 and axes J1 and J2 as its vertices. In this parallelogram Q1, the line Q11 connecting the rotation axis A2 and axis J1 and the line Q12 connecting the rotation axis A3 and axis J2 remain parallel even under deformation. Therefore, when the link 131a rotates around the rotation axis A2, the third arm 123 rotates around the rotation axis A3 while maintaining the parallel state of lines Q11 and Q12.

[0090] The link mechanism 131 has been described above, but the configuration of the link mechanism 131 is not particularly limited as long as it can rotate the third arm 123 relative to the second arm 122 around the rotation axis A3.

[0091] Next, the link mechanism 132 will be described. As shown in Figure 16, the link mechanism 132 is a mechanism for maintaining a constant posture of the fourth arm 124 so that the rotation axis A5 is always aligned with the Z axis, regardless of the posture of the second arm 122 and the third arm 123. Such a link mechanism 132 includes links 132a, 132b, and 132c, and pivots 132d, 132e, 132f, and 132g.

[0092] Link 132a is a rod-shaped link extending in a direction perpendicular to the rotation axis A2 and is arranged parallel to the second arm 122. At its base end, link 132a is rotatably connected to the upper end of the first arm 121 via a pivot 132d, around an axis J3 parallel to the rotation axis A2. Note that axis J3 is spaced apart from the rotation axis A2.

[0093] Link 132b is a triangular plate with the X-axis as its normal, and is rotatably held on the shaft 31 at one corner via a third connecting portion 34. Furthermore, at the corner located on its base end, link 132b is rotatably connected to the tip of link 132a via a pivot 132e around an axis J4 parallel to the rotation axis A3. Note that axis J4 is spaced apart from the rotation axis A3.

[0094] Link 132c is a rod-shaped link extending in a direction perpendicular to the rotation axis A3 and is arranged parallel to the third arm 123. At its base end, link 132c is rotatably connected to the corner of the tip end of link 132b via pivot 132f around an axis J5 parallel to the rotation axis A3. Note that axis J5 is spaced away from the rotation axis A3. Furthermore, at its tip end, link 132c is rotatably connected to the base end of the fourth arm 124 via pivot 132g around an axis J6 parallel to the rotation axis A4. Note that axis J6 is spaced away from the rotation axis A4. In other words, link 132c connects a position of link 132b offset from the rotation axis A3 to a position of the fourth arm 124 offset from the rotation axis A4.

[0095] In such a link mechanism 132, a parallelogram Q2 is formed in a plan view from the X-axis direction, with the rotation axes A2 and A3 and axes J3 and J4 as its vertices. In this parallelogram Q2, the line Q21 connecting the rotation axis A2 and axis J3 and the line Q22 connecting the rotation axis A3 and axis J4 remain parallel even under deformation. Furthermore, a parallelogram Q3 is formed in a plan view from the X-axis direction, with the rotation axes A3 and A4 and axes J5 and J6 as its vertices. In this parallelogram, the line Q31 connecting the rotation axis A3 and axis J5 and the line Q32 connecting the rotation axis A4 and axis J6 remain parallel even under deformation.

[0096] Furthermore, the inclination of the straight line Q21 with respect to the Z axis is constant regardless of the posture of the second and third arms 122 and 123. Therefore, the straight line Q22, which is paired with the straight line Q21, is also constant regardless of the posture of the second and third arms 122 and 123, and as a result, the posture of link 132b is also constant. Also, because the posture of link 132b is constant, the paired straight lines Q31 and Q32 are also constant regardless of the posture of the second and third arms 122 and 123. Therefore, regardless of the posture of the second and third arms 122 and 123, the fourth arm 124 is maintained in a constant posture, that is, in a posture where the rotation axis A5 is aligned with the Z axis. By configuring the robot to mechanically maintain a constant posture in this way, electrical control becomes unnecessary, and the control of the robot 10 becomes easier. Note that "maintaining a constant posture of the fourth arm 124" means allowing slight changes in posture, for example, changes within a range of 5 degrees or less with respect to the Z axis.

[0097] The link mechanism 132 has been described above. In this link mechanism 132, the link 132b is connected to the shaft 31 in the portion between the first connection part 32 and the second connection part 33. With this configuration, the protrusion of the link 132b to the side of the third arm 123 is suppressed, making it possible to miniaturize the robot 10. In addition, the center of gravity of the robot arm 120 is less likely to shift in the X-axis direction with respect to the rotation axis A1, improving the weight balance of the robot arm 120.

[0098] Furthermore, in a plan view from a direction perpendicular to the X-axis direction and the direction in which the rotation axes A3 and A4 are aligned, that is, the longitudinal direction of the third arm 123, link 132c overlaps with the third arm 123. In other words, link 132c is located between the side plate portions 42 and 43. With this configuration, the protrusion of link 132c to the side of the third arm 123 is suppressed, making it possible to miniaturize the robot 10. In addition, the center of gravity of the robot arm 120 becomes less likely to shift in the X-axis direction relative to the rotation axis A1, improving the weight balance of the robot arm 120.

[0099] The robot system 1 has been described above. The robot 10 of this robot system 1 has, as previously mentioned, a base 110, a first arm 121, a second arm 122, and a third arm 123 which are base arms connected to the base 110 and rotate around a rotation axis A1 which is a base rotation axis relative to the base 110, and a fourth arm 124 which is an end arm connected to the third arm 123 and rotates around a rotation axis A4 which is an intermediate rotation axis relative to the third arm 123. The fourth arm 124 also has an arm base 50, an end shaft portion 125 which rotates around a rotation axis A5 which is an end rotation axis parallel to and separated from the rotation axis A1 relative to the arm base 50, a motor 61 which has an output shaft 611 which rotates around a rotation axis B1 which is a first rotation axis parallel to the rotation axis A5, and a power transmission portion 62 which transmits the rotation of the output shaft 611 to the end shaft portion 125. Furthermore, the power transmission unit 62 includes an input-side rotation transmission member 621 as a first rotation transmission member located on the output shaft 611, an output-side rotation transmission member 622 as a second rotation transmission member located on the tip shaft portion 125, an intermediate rotation transmission member 623 that rotates around a rotation axis B2 which is a second rotation axis parallel to the rotation axis A5 with respect to the arm base 50, a first annular member 624 wrapped around the input-side rotation transmission member 621 and the intermediate rotation transmission member 623, and a second annular member 625 wrapped around the intermediate rotation transmission member 623 and the output-side rotation transmission member 622. In a plan view from the direction along the rotation axis A5, the rotation axes B1 and B2 are located on opposite sides of each other with respect to a virtual straight line LL connecting the rotation axes A5 and A1. With this configuration, the tip shaft 125, motor 61, and power transmission unit 62 can be balanced and positioned on the fourth arm 124, minimizing the weight difference between the portion on the positive X-axis side of the virtual straight line LL and the portion on the negative X-axis side of the virtual straight line LL. As a result, twisting of the robot arm 120 during operation can be effectively suppressed, improving the stability of the robot 10. Consequently, the cycle time for operations can be shortened, and productivity can be improved.

[0100] Furthermore, as mentioned above, the intermediate rotation transmission member 623 has a third rotation transmission member 623a, which has a larger diameter than the input-side rotation transmission member 621 and around which the first annular member 624 is wrapped, and a fourth rotation transmission member 623b, which has a smaller diameter than the output-side rotation transmission member 622 and around which the second annular member 625 is wrapped. With this configuration, the power transmission unit 62 functions as a two-stage reduction gear. As a result, the tip shaft 125 can be rotated with greater torque. Also, because the reduction ratio by the power transmission unit 62 is large, a high-speed motor 61 can be used. High-speed motors tend to have smaller drive currents and be smaller in size, so the motor 61 can be made smaller. As a result, the tip weight of the robot arm 120 can be reduced, and vibrations of the robot arm 120 can be effectively suppressed.

[0101] Furthermore, as mentioned above, the rotation axes B1 and B2 are located between the rotation axis A5 and the rotation axis A1. With this configuration, the center of gravity of the fourth arm 124 can be shifted towards the rotation axis A1, and the inertia of the robot arm 120 around the rotation axis A1 is reduced. As a result, the load torque on the robot arm 120 is reduced, and the settlingability of the robot 10 is improved.

[0102] Furthermore, as mentioned above, in a plan view from the direction along the rotation axis A5, the rotation axis A4 is located between the rotation axis A5 and the rotation axis A1, and the rotation axes B1 and B2 are located between the rotation axis A5 and the rotation axis A4. With this configuration, the motor 61 and the intermediate rotation transmission member 623 are not too far apart from the rotation axis A5. As a result, the tip shaft portion 125, the motor 61 and the intermediate rotation transmission member 623 can be arranged compactly, and the fourth arm 124 can be miniaturized.

[0103] Furthermore, as mentioned above, the rotating shafts B1 and B2 are positioned so as to be biased towards the rotating shaft A4 side compared to the rotating shaft A5. With this configuration, the rotating shaft A5 and the rotating shafts B1 and B2 are appropriately separated, making it easier to increase the outer diameter of the output side rotation transmission member 622 and the third rotation transmission member 623a. As a result, the power transmission unit 62 can be a speed reducer with a larger reduction ratio.

[0104] Furthermore, as mentioned above, in a plan view from the direction along the rotation axis A5, the rotation axis B2 is located between the rotation axis A5 and the rotation axis B1. With this configuration, the intermediate rotation transmission member 623, which tends to have a larger plan view shape than the motor 61, is less likely to protrude from the arm base 50. As a result, contact between the intermediate rotation transmission member 623 and other parts is suppressed, and the driving of the robot 10 becomes stable.

[0105] Furthermore, as mentioned above, the tip shaft portion 125 is hollow and has through holes 125a that penetrate both end faces. With this configuration, for example, wiring and piping connected to the end effector can be routed through the through holes 125a. Therefore, the exposure of wiring and piping around the end effector can be reduced, and wiring and piping are less likely to get in the way of work.

[0106] Furthermore, as mentioned above, in a plan view from the direction along the rotation axis A5, the opening at the base end of the through hole 125a does not overlap with the motor 61 and the power transmission unit 62. With this configuration, wiring and piping to the through hole 125a can be easily routed.

[0107] <Second Embodiment> Figure 17 is a top view of the fourth arm of the robot according to the second embodiment.

[0108] This embodiment is the same as the first embodiment described above, except that the configuration of the power transmission unit 62 is different. In the following description, this embodiment will be described mainly in terms of the differences from the first embodiment described above, and similar matters will not be described. Also, in the figures of this embodiment, the same reference numerals are used for components that are the same as in the previously described embodiment.

[0109] As shown in Figure 17, the power transmission unit 62 of this embodiment has two intermediate rotation transmission members 623 and is a reduction gear with a three-stage reduction mechanism. Hereinafter, one of the intermediate rotation transmission members 623 (on the input side rotation transmission member 621 side) will also be referred to as intermediate rotation transmission member 623A, and the other intermediate rotation transmission member 623 (on the output side rotation transmission member 622 side) will also be referred to as intermediate rotation transmission member 623B. Furthermore, hereafter, the rotation axis of intermediate rotation transmission member 623A will also be referred to as rotation axis B21, and the rotation axis of intermediate rotation transmission member 623B will also be referred to as rotation axis B22. Furthermore, the power transmission unit 62 of this embodiment includes a first annular member 624 wrapped around the input-side rotation transmission member 621 and the third rotation transmission member 623a of the intermediate rotation transmission member 623A, a third annular member 626 wrapped around the fourth rotation transmission member 623b of the intermediate rotation transmission member 623A and the third rotation transmission member 623a of the intermediate rotation transmission member 623B, and a second annular member 625 wrapped around the fourth rotation transmission member 623b of the intermediate rotation transmission member 623B and the output-side rotation transmission member 622.

[0110] In this way, the power transmission unit 62 is equipped with a three-stage reduction mechanism, which reduces the rotation of the output shaft 611 in three stages, allowing the tip shaft 125 to be rotated with greater torque. Furthermore, because the reduction ratio by the power transmission unit 62 is large, a high-speed motor 61 can be used. In this embodiment, the intermediate rotation transmission members 623A and 623B have the same configuration, but this is not limited to this, and they may have different configurations, such as the third rotation transmission member 623a and the fourth rotation transmission member 623b having different outer diameters. Also, the number of intermediate rotation transmission members 623 is not limited to two, but may be three or more.

[0111] Furthermore, in a plan view from a direction along the rotation axis A5 (Z axis), the rotation axes B1 and B21 and B22 are located on opposite sides of the virtual straight line LL. This arrangement allows the tip shaft 125, motor 61, and power transmission unit 62 to be balanced on the fourth arm 124, minimizing the weight difference between the portion on the positive X-axis side of the virtual straight line LL and the portion on the negative X-axis side of the virtual straight line LL. As a result, the settling ability of the robot 10 is improved.

[0112] In this embodiment, both rotation axes B21 and B22 are located on the opposite side of the motor 61 from the virtual straight line LL, but this is not limited to this configuration. For example, depending on the weight difference between the motor 61 and the intermediate rotation transmission members 623A and 623B, either one of the rotation axes B21 or B22 may be positioned on the same side as the motor 61 with respect to the virtual straight line LL. By having multiple intermediate rotation transmission members 623 in this way, the arrangement of the intermediate rotation transmission members 623A and 623B can be selected according to the weight of each part, making it easier to balance the weight of the fourth arm 124.

[0113] As described above, in this embodiment, the power transmission unit 62 has a plurality of intermediate rotation transmission members 623. With this configuration, the arrangement of the plurality of intermediate rotation transmission members 623 can be selected according to the weight of each part, making it easier to balance the weight of the fourth arm 124.

[0114] This second embodiment can also achieve the same effects as the first embodiment described above.

[0115] Although the robot of the present invention has been described above in the illustrated embodiments, the present invention is not limited to these embodiments. Furthermore, each part of the robot can be replaced with any structure capable of performing similar functions. In addition, any structure may be added to the robot.

[0116] 1...Robot system, 10...Robot, 110...Base, 120...Robot arm, 121...First arm, 122...Second arm, 123...Third arm, 124...Fourth arm, 125...Tip shaft, 125a...Through hole, 131...Link mechanism, 131a...Link, 131b...Link, 131c...Pivot, 131d...Pivot, 132...Link mechanism, 132a...Link, 132b...Link, 132c...Link, 132d...Pivot, 132e...Pivot, 132f...Pivot, 132g...Pivot, 140...First drive unit, 141...Motor, 141a... Output shaft, 142...power transmission section, 142a...input side rotation transmission member, 142b...output side rotation transmission member, 142c...annular member, 150...second drive unit, 151...motor, 151a...output shaft, 152...power transmission section, 152a...input side rotation transmission member, 152b...output side rotation transmission member, 152c...annular member, 160...third drive unit, 161...motor, 161a...output shaft, 162...power transmission section, 162a...input side rotation transmission member, 162b...output side rotation transmission member, 162c...annular member, 163...bearing section, 20...arm base, 21...shaft, 22...bearing section 23...bearing section, 30...arm base, 31...shaft, 32...first connection section, 321...first bearing section, 322...first bearing retaining section, 33...second connection section, 331...second bearing section, 332...second bearing retaining section, 34...third connection section, 341...third bearing section, 342...third bearing retaining section, 35...regulating section, 351...flange, 352...spacer, 353...spacer, 354...spacer, 355...spacer, 356...nut, 357...nut, 40...arm base, 40a...first base piece, 40b...second base piece, 41...bottom section, 42...side plate section, 421...shaft insertion hole, 422...Shaft insertion hole, 43...Side plate section, 431...Shaft insertion hole, 432...Shaft insertion hole, 50...Arm base, 50a...First base piece, 50b...Second base piece, 500...Restricting section, 501...Flange, 502...Flange, 503...Spacer, 504...Spacer, 505...Spacer, 506...Spacer, 507...Spacer, 508...Nut, 509...Nut, 51...Bottom section, 52...Side plate section, 521...Shaft insertion hole, 53...Side plate section, 531...Shaft insertion hole, 54...Shaft, 55...Shaft holding section, 551...Bearing section, 552...Bearing holding section,56...Shaft holding part, 561...Bearing part, 562...Bearing holding part, 57...Mounting part, 58...Mounting part, 59...Connecting part, 60...Drive unit, 61...Motor, 611...Output shaft, 62...Power transmission part, 621...Input side rotation transmission member, 622...Output side rotation transmission member, 623...Intermediate rotation transmission member, 623A...Intermediate rotation transmission member, 623B...Intermediate rotation transmission member, 623a...Third rotation transmission member, 623b...Fourth rotation transmission member, 624...First annular member, 625...Second annular member, 626...Third annular member, 6 8...Holding part, 681...Bearing part, 682...Bearing holding part, 69...Support part, 90...Control device, A1...Rotation shaft, A2...Rotation shaft, A3...Rotation shaft, A4...Rotation shaft, A5...Rotation shaft, B1...Rotation shaft, B2...Rotation shaft, B21...Rotation shaft, B22...Rotation shaft, J1...Shaft, J2...Shaft, J3...Shaft, J4...Shaft, J5...Shaft, J6...Shaft, LL...Virtual line, Q1...Parallelogram, Q11...Line, Q12...Line, Q2...Parallelogram, Q21...Line, Q22...Line, Q3...Parallelogram, Q31...Line, Q32...Line, V...Radial direction,

Claims

1. The device comprises a base, a base arm connected to the base and rotating around a base rotation axis relative to the base, and a tip arm connected to the base arm and rotating around an intermediate rotation axis relative to the base arm, wherein the tip arm comprises an arm base, a tip shaft portion rotating around a tip rotation axis parallel to and spaced apart from the base rotation axis relative to the arm base, a motor having an output shaft rotating around a first rotation axis parallel to the tip rotation axis, and a power transmission unit that transmits the rotation of the output shaft to the tip shaft portion, wherein the power transmission unit comprises a first rotation transmission member positioned on the output shaft, a second rotation transmission member positioned on the tip shaft portion, an intermediate rotation transmission member rotating around a second rotation axis parallel to the tip rotation axis relative to the arm base, a first annular member wrapped around the first rotation transmission member and the intermediate rotation transmission member, and a second annular member wrapped around the intermediate rotation transmission member and the second rotation transmission member. A robot characterized in that, in a plan view from a direction along the tip rotation axis, the first rotation axis and the second rotation axis are located on opposite sides of a virtual line connecting the tip rotation axis and the base rotation axis.

2. The robot according to claim 1, wherein the intermediate rotational transmission member comprises a third rotational transmission member having a larger diameter than the first rotational transmission member around which the first annular member is wrapped, and a fourth rotational transmission member having a smaller diameter than the second rotational transmission member around which the second annular member is wrapped.

3. The robot according to claim 1, wherein the first rotation axis and the second rotation axis are located between the tip rotation axis and the base rotation axis.

4. The robot according to claim 3, wherein, in a plan view from a direction along the tip rotation axis, the intermediate rotation axis is located between the tip rotation axis and the base rotation axis, and the first rotation axis and the second rotation axis are located between the tip rotation axis and the intermediate rotation axis.

5. The robot according to claim 4, wherein the first rotation axis and the second rotation axis are each positioned so as to be biased toward the intermediate rotation axis than toward the tip rotation axis.

6. The robot according to claim 5, wherein, in a plan view from a direction along the tip rotation axis, the second rotation axis is located between the tip rotation axis and the first rotation axis.

7. The robot according to claim 1, wherein the power transmission unit has a plurality of intermediate rotation transmission members.

8. The robot according to claim 1, wherein the tip shaft portion is hollow and has through holes penetrating both end faces.

9. The robot according to claim 8, wherein, in a plan view from a direction along the tip rotation axis, the opening on the base end side of the through hole does not overlap with the motor and the power transmission unit.

Images