robot

Abstract

We provide robots that are easy to assemble and maintain. [Solution] The robot has a first arm that rotates around a first rotation axis and a second arm that rotates around a second rotation axis relative to the first arm. The first arm has a shaft arranged along the second rotation axis, a first arm base that supports the shaft except for both ends thereof, a first connecting portion arranged on the shaft on one side in the direction along the second rotation axis relative to the first arm base, and a second connecting portion arranged on the shaft on the other side. The second arm has a second arm base which is connected so that a first base piece inserted into one end of the shaft from outside the first connecting portion and fixed to the first connecting portion and a second base piece inserted into the other end of the shaft from outside the second connecting portion and fixed to the second connecting portion are detachable.

Description

Technical Field

[0001] The present invention relates to a robot.

Background Art

[0002] The robot described in Patent Document 1 is a so-called "parallel link robot", which includes a base, a first arm that rotates around a first rotation axis with respect to the base, a second arm that rotates around a second rotation axis parallel to the first rotation axis with respect to the first arm, a first drive source for rotationally driving the first arm, a second drive source for rotationally driving the second arm, a link mechanism that is connected to the tip side of the first arm via a plurality of links starting from the base end side of the first arm and transmits the rotational force generated by the second drive source to the second arm.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in such a robot, no consideration is given to the detachable property of the second arm with respect to the first arm. Therefore, there is a problem that the assemblability and maintainability are low.

Means for Solving the Problems

[0005] The robot according to an application example of the present invention includes a first arm that rotates around a first rotation axis, a second arm that is connected to the first arm and rotates around a second rotation axis with respect to the first arm, The first arm, a shaft disposed along the second rotation axis, A first arm base supports the shaft in portions excluding both ends of the shaft, A first connecting portion is positioned on the shaft on one side of the first arm base in the direction along the second rotation axis, It has a second connecting portion located on the shaft on the other side of the first arm base in the direction along the second rotation axis, The second arm is, The second arm base is connected in such a way that it can be separated a first base piece, which is inserted into one end of the shaft from the outside of the first connection and fixed to the first connection, and a second base piece, which is inserted into the other end of the shaft from the outside of the second connection and fixed to the second connection. [Brief explanation of the drawing]

[0006] [Figure 1] Figure 1 is a perspective view showing a robot system according to the first embodiment. [Figure 2] Figure 2 is a cross-sectional view of the first arm. [Figure 3] Figure 3 is a cross-sectional view of the base end of the third arm. [Figure 4] Figure 4 is a perspective view of the arm base of the third arm. [Figure 5] Figure 5 is a cross-sectional view of the tip of the third arm. [Figure 6] Figure 6 is a cross-sectional view showing the procedure for attaching the third arm to the second arm. [Figure 7] Figure 7 is a cross-sectional view showing the procedure for attaching the third arm to the second arm. [Figure 8] Figure 8 is a front view of the fourth arm. [Figure 9] Figure 9 is a front view showing the procedure for attaching the fourth arm to the third arm. [Figure 10] Figure 10 is a front view showing the procedure for attaching the fourth arm to the third arm. [Figure 11] Figure 11 is a partial cross-sectional view showing the fourth arm. [Figure 12] Figure 12 is a cross-sectional view of the tip shaft located on the fourth arm. [Figure 13] Figure 13 is a partial cross-sectional view showing the intermediate rotation transmission member located in the fourth arm. [Figure 14] Figure 14 is a top view showing the arrangement of the motor's rotating shaft, the intermediate rotation transmission member's rotating shaft, and the tip shaft's rotating shaft. [Figure 15] Figure 15 is a partial cross-sectional view showing the first drive unit. [Figure 16] Figure 16 is a side view showing the linkage mechanism. [Figure 17] Figure 17 is a perspective view of the third arm of the robot according to the second embodiment. [Figure 18] Figure 18 is a cross-sectional view of the third arm. [Figure 19] Figure 19 is a cross-sectional view of the base end of the third arm of the robot according to the third embodiment. [Modes for carrying out the invention]

[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, while the X-axis and Y-axis are aligned horizontally. In the following, the direction along the X-axis will also be referred to as the X-axis direction, the direction along the Y-axis as the Y-axis direction, and the direction along 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] In addition, in this specification, descriptions such as "orthogonal", "parallel", and "symmetric" all mean "orthogonal", "parallel", and "symmetric" to the extent that manufacturing errors are tolerated. Specifically, "orthogonal" means substantially orthogonal, including the range where the angle formed by two straight lines or two planes is 80 degrees or more and 100 degrees or less. "Parallel" means substantially parallel, including the range where the angle formed by two straight lines or two planes is 0 degrees or more and 10 degrees or less. "Symmetric" means substantially symmetric, including the range where the ratio of the overlapping area to the total area of one of the two elements is 90% or more and 100% or less when one of the two elements is overlapped with the other.

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

[0010] The robot system 1 shown in FIG. 1 includes 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 various parts 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 various parts 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 used in food manufacturing in a broad sense, including, for example, food handling, 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 arm 121 to 124 will be described in order. In this embodiment, the second arm 122 is the "first arm" of the present invention, the third arm 123 is the "second arm" of the present invention, and the fourth arm 124 is the "third arm" of the present invention. Also, the rotation axis A2 is the "first rotation axis" of the present invention, the rotation axis A3 is the "second rotation axis" of the present invention, and the rotation axis A4 is the "third rotation axis" of the present invention.

[0016] (First arm 121) First, let's describe the first arm 121. The first arm 121 is located above the base 110 and is rotatable around the rotation axis A1 relative to the base 110. As shown in Figure 2, this 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 mentioned above, in this embodiment, the second arm 122 constitutes the "first arm" of the present invention. 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 an arm base 30, which is a rod-shaped first arm base 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 robot 10, the rotation axis A3 is formed by this shaft 31. The arm base 30 supports the shaft 31 in its central part, that is, the part excluding both ends. Therefore, both ends of the shaft 31 protrude from the arm base 30 on both sides 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 X-axis side relative to the arm base 30, and the second connecting portion 33 is located on the negative X-axis side relative to the arm base 30. In other words, the first and second connecting portions 32 and 33 are located on opposite sides of the X-axis 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. In addition, 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 located between the first connecting portion 32 and the arm base 30, and a spacer 352 is located 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 spacers 353 and 354, and the position of the third connecting portion 34 is fixed. Also, the second connecting portion 33 is sandwiched between 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 parts 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 parts 32, 33, and 34 is improved.

[0029] (Third arm 123) Next, the third arm 123 will be described. As mentioned above, in this embodiment, the third arm 123 constitutes the "second arm" of the present invention. As shown in Figure 1, the third arm 123 is located on the tip side of the second arm 122 and is rotatable relative to the second arm 122 around the rotation axis A3. The third arm 123 also has an arm base 40 as a second arm base 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 to 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 to 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 to 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 to 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. This configuration makes it easy to attach and detach the third arm 123 to 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, one end of the shaft 31 is inserted through the shaft insertion hole 421 of the side plate portion 42, as shown in Figure 6, and the side plate portion 42 and the first bearing holder 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 holder 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] (4th arm 124) Next, the fourth arm 124 will be described. As mentioned above, in this embodiment, the fourth arm 124 constitutes the "third arm" of the present invention. As shown in Figure 1, the fourth arm 124 is located on the tip side of the third arm 123 and is rotatable relative to the third arm 123 about the rotation axis A4. 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, i.e., the XY 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 section on the link mechanism 132.

[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. Therefore, 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] Furthermore, 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, the protrusion of the shaft holding portions 55 and 56 outside the arm base 50 can be suppressed, 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 positioned 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 disc-shaped flanges that project radially from the outer circumference of the shaft 54. Furthermore, the mounting portions 57 and 58 are formed separately from the shaft 54 ​​and are fixed to the shaft 54 ​​by methods such as screw fastening. The shaft 54 ​​is then 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 multiple screws, and around the shaft 54, the mounting portion 58 is fixed to the side plate portion 43 by multiple screws. By making the mounting portions 57 and 58 flange-shaped, their construction is simplified, and they are easier to fix to the third arm 123 around the shaft 54. Additionally, by fixing the mounting portions 57 and 58 to the third arm 123 by screw fastening, they can be easily attached and detached.

[0045] Thus, forming the mounting portions 57 and 58 separately from the shaft 54 ​​makes their formation easier. Furthermore, the degree of freedom in the shape and material of the shaft 54 ​​and the mounting portions 57 and 58 is increased. However, this is not limited to this; for example, at least one of the mounting portions 57 and 58 may be formed integrally with the shaft 54. Forming at least one of the mounting portions 57 and 58 integrally with the shaft 54 ​​also makes their formation easier. Additionally, since the work of fixing at least one of the mounting portions 57 and 58 to the shaft 54 ​​is unnecessary, the assembly of the robot 10 becomes easier. Furthermore, since there is no displacement of at least one of the mounting portions 57 and 58 relative to the shaft 54, the driving of the robot 10 becomes stable over the long term. In this embodiment, it is preferable that only the mounting portion 57 is integrally formed with the shaft 54, and the mounting portion 58 is not integrally formed with the shaft 54, in order to facilitate the work of inserting the bearing portion 561 onto the shaft 54.

[0046] The procedure for attaching the fourth arm 124 to the third arm 123 is as follows: 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 Figure 10, the mounting portion 57 is located on the outside of the side plate portion 42, that is, on the positive side in the X-axis direction. The screws that fix the mounting portion 57 to the side plate portion 42 are tightened from the side plate portion 42 side. The shaft holding portion 55 is located close to the outside of the side plate portion 42, that is, on the positive side in the X-axis direction, making it difficult to secure space for screw fastening. In contrast, there is more space on the inside of the side plate portion 42 than on the outside. Therefore, as in this embodiment, by tightening the screws from the side plate portion 42 side, it becomes easier to secure space for screw fastening, and the work can be performed smoothly. On the other hand, the mounting portion 58 is located on the inside of the side plate portion 43, that is, on the positive side in the X-axis direction. The screws that fix the mounting portion 58 to the side plate portion 43 are tightened from the side plate portion 43 side. As a result, the heads of the screws are exposed on the outside, making it easy to attach and detach the screws. This configuration makes it easy to attach and detach the fourth arm 124 to the third arm 123, improving the ease of assembly and maintenance of the robot 10.

[0048] Furthermore, as mentioned above, since the mounting portion 57 is positioned between the shaft holding portions 55 and 56, the shaft 54 ​​is fixed to the side plate portion 42 via the mounting portion 57 in the portion between the shaft holding portions 55 and 56. With this configuration, the central part of the shaft 54 ​​is supported by the third arm 123, making it difficult for the shaft 54 ​​to bend. As a result, the rotation axis A4 is less likely to wobble, and the rotation of the fourth arm 124 is stable.

[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. In addition, 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, fixing their positions.

[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, fixing their positions.

[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 rotatably around a rotation axis A5 along the Z-axis relative to the base 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 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 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 rotational transmission member 621 as a first rotational transmission member, an output-side rotational transmission member 622 as a second rotational transmission member, an intermediate rotational transmission member 623, a first annular member 624 wrapped around the input-side rotational transmission member 621 and the intermediate rotational transmission member 623, and a second annular member 625 wrapped around the intermediate rotational transmission member 623 and the output-side rotational 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 along the Z axis relative to the bottom portion 51. The rotation axis B2 is parallel to the rotation axis A1 and is spaced apart from rotation axes A1 and B1. In other words, rotation axes A5, B1, and B2 are parallel to each other and spaced apart 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 it can rotatably hold the intermediate rotation transmission member 623 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 sides by the bottom portion 51 and the support portion 69 via a pair of holding portions 68.

[0060] Furthermore, 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. These 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 positioned parallel to 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 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 operation can be effectively suppressed, improving the settability of the robot 10, i.e., the accuracy of its operation. Consequently, the cycle time of the operation can be shortened, and productivity can be 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 on 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), rotation axis A4 is located between rotation axis A5 and rotation axis A1. Rotation axes B1 and B2 are located between rotation axis A5 and 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 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 rotation axes B1 and B2 does not have to be between rotation axis A5 and 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 unit 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 configuration, and the rotation axis B2 does not necessarily 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 arm from 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 the rotation axis A1 relative to the base 110, a second drive unit 150 for rotating the second arm 122 around the rotation axis A2 relative to the first arm 121, and a third drive unit 160 for rotating the third arm 123 around the 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 within 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, specifically 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 / 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 composed of a single-stage reduction gear, but it may be composed of two or more stages of reduction gears. 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 / 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 together 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 device 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 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. In this way, by using a reduction gear as the power transmission unit 162, 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 axis J1, which is parallel to the rotation axis A2. Note that axis J1 is separated from the rotation axis A2. At its tip end, link 131b is rotatably connected to the base end of the third arm 123 via pivot 131d around axis J2, which is 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 around the rotation axis A3 relative to the second arm 122.

[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 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, as the first link, 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. Link 132b is also rotatably connected at the corner located on its base end 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, acting as the second link, is a rod-shaped structure extending perpendicular to the rotation axis A3 and is arranged parallel to the third arm 123. At its base, link 132c is rotatably connected to the corner of the tip side of link 132b via pivot 132f, around axis J5 which is parallel to the rotation axis A3. Note that axis J5 is spaced away from the rotation axis A3. Furthermore, at its tip, link 132c is rotatably connected to the base end of the fourth arm 124 via pivot 132g, around axis J6 which is 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, with the rotation axis A5 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 becomes 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, which is along the rotation axis A3, and the direction in which rotation axes A3 and A4 are aligned, i.e., 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 plates 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 second arm 122 which is a first arm that rotates around a rotation axis A2 which is a first rotation axis, and a third arm 123 which is a second arm connected to the second arm 122 and rotates around a rotation axis A3 which is a second rotation axis relative to the second arm 122. The second arm 122 also has a shaft 31 arranged along the rotation axis A3, an arm base 30 which is a first arm base that supports the shaft 31 in parts of the shaft 31 excluding both ends, a first connecting part 32 arranged on the shaft 31 on one side of the arm base 30 in the direction along the rotation axis A3, and a second connecting part 33 arranged on the shaft 31 on the other side of the arm base 30 in the direction along the rotation axis A3. Furthermore, the third arm 123 has an arm base 40 which is a second arm base, formed by connecting a first base piece 40a, which is inserted into one end of the shaft 31 (positive X-axis side) from the outside of the first connection part 32 (positive X-axis side) and fixed to the first connection part 31, and a second base piece 40b, which is inserted into the other end of the shaft 31 (negative X-axis side) from the outside of the second connection part 33 (negative X-axis side) and fixed to the second connection part 33, so that they can be separated. With this configuration, the attachment and detachment of the third arm 123 to the second arm 122 becomes easy. As a result, the assembly and maintenance of the robot 10 are improved.

[0100] Furthermore, as mentioned above, the first base piece 40a and the second base piece 40b are connected by screws. With this configuration, the first base piece 40a and the second base piece 40b can be easily connected or separated.

[0101] As mentioned above, 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, with the first base piece 40a fixed to the first bearing retaining portion 322. 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, with the second base piece 40b fixed to the second bearing retaining portion 332. With this configuration, the arm base 40 is connected to the shaft 31 so as to be rotatable around the rotation axis A3.

[0102] Furthermore, as mentioned above, the first bearing section 321 and the second bearing section 331 are both deep groove ball bearings. With this configuration, the manufacturing cost of the robot 10 can be effectively reduced, and the robot 10 can be provided at a lower cost. In addition, because deep groove ball bearings have a simple structure and are small, it is possible to make the robot 10 smaller and lighter.

[0103] As mentioned above, the robot 10 has a fourth arm 124 which is a third arm connected to the third arm 123 and rotates around a rotation axis A4 which is a third rotation axis parallel to the rotation axis A3 relative to the third arm 123; a first link 132b which is connected to the shaft 31 and maintains a constant posture regardless of the posture of the second arm 122 and the third arm 123; and a second link 132c which connects a position of link 132b offset from the rotation axis A3 and a position of the fourth arm 124 offset from the rotation axis A4. Thus, the fourth arm 124 is maintained in a constant posture regardless of the posture of the second arm 122 and the third arm 123. With this configuration, the fourth arm 124 can be mechanically maintained in a constant posture, making it easier to control the robot 10.

[0104] Furthermore, as mentioned above, link 132b is connected to shaft 31 in the portion between the first connection part 32 and the second connection part. With this configuration, the protrusion of link 132b to the side of the third arm 123 is suppressed, making it possible to miniaturize the robot 10.

[0105] Furthermore, as mentioned above, in a plan view from a direction perpendicular to the direction along the rotation axis A3 and the direction in which the rotation axes A2 and A3 are aligned, the second link 132c overlaps with the third arm 123. With this configuration, the protrusion of the 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.

[0106] <Second Embodiment> Figure 17 is a perspective view of the third arm of the robot according to the second embodiment. Figure 18 is a cross-sectional view of the third arm.

[0107] This embodiment is the same as the first embodiment described above, except that the configuration of the third arm 123 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.

[0108] As shown in Figures 17 and 18, in the third arm 123 of this embodiment, the arm base 40 further has a connecting portion 40c that connects the first base piece 40a and the second base piece 40b. The connecting portion 40c is a U-shaped plate member formed by bending sheet metal such as a steel plate, and is fixed with screws at one end to the side plate portion 42 of the first base piece 40a, and fixed with screws at the other end to the side plate portion 43 of the second base piece 40b. With this configuration, the arm base 40 is reinforced by the connecting portion 40c, and the rigidity of the arm base 40 can be increased. Therefore, unwanted vibrations of the tip shaft portion 125 can be effectively suppressed.

[0109] In particular, since the connecting portion 40c is screw-fastened to the first and second base pieces 40a and 40b, it is easy to attach and detach the connecting portion 40c to the first and second base pieces 40a and 40b. Therefore, adding the connecting portion 40c has almost no effect on the assembly and maintenance of the robot 10. In other words, when attaching the third arm 123 to the second arm 122, the first and second base pieces 40a and 40b should be attached to the shaft 31 as in the first embodiment described above, and then the connecting portion 40c should be attached to the first and second base pieces 40a and 40b. Conversely, when removing the third arm 123 from the second arm 122, the connecting portion 40c should be removed from the first and second base pieces 40a and 40b, and then the first and second base pieces 40a and 40b should be removed from the shaft 31.

[0110] This second embodiment can also achieve the same effects as the first embodiment described above.

[0111] <Third Embodiment> Figure 19 is a cross-sectional view of the base end of the third arm of the robot according to the third embodiment.

[0112] This embodiment is the same as the first embodiment described above, except that the configuration of the third arm 123 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.

[0113] As shown in Figure 19, in the third arm 123 of this embodiment, the shaft insertion holes 421 and 431 are omitted from the side plate portions 42 and 43. Also, the first and second bearing retaining portions 322 and 332 of the first and second connecting portions 32 and 33 extend beyond both ends of the shaft 31. On the outside of the shaft 31, the side plate portions 42 and 43 are fixed to the first and second bearing retaining portions 322 and 332.

[0114] This third 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. [Explanation of Symbols]

[0116] 1...Robot system, 10...Robot, 110...Base, 120...Robot arm, 121...First arm, 122...Second arm, 123...Third arm, 124...Fourth arm, 125...End 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... 30...Bearing section, 31...Arm base, 32...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...Restricting 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, 40c...Connecting section, 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... Regulating 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...Third rotation transmission member, 623b...Fourth rotation transmission member, 624...First annular member, 625...Second annular member, 68...Holding part, 681...Bearing Part, 682...bearing holding part, 69...support part, 90...control device, A1...rotating shaft, A2...rotating shaft, A3...rotating shaft, A4...rotating shaft, A5...rotating shaft, B1...rotating shaft, B2...rotating 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. A first arm that rotates around a first axis of rotation, It has a second arm connected to the first arm and rotating relative to the first arm around a second axis of rotation, The first arm is, A shaft arranged along the second axis of rotation, A first arm base supports the shaft in portions excluding both ends of the shaft, A first connecting portion is positioned on the shaft on one side of the first arm base in the direction along the second rotation axis, It has a second connecting portion located on the shaft on the other side of the first arm base in the direction along the second rotation axis, The second arm is, A robot characterized by having a second arm base, which is connected in such a way that it can be separated a first base piece inserted into one end of the shaft from the outside of the first connection and fixed to the first connection, and a second base piece inserted into the other end of the shaft from the outside of the second connection and fixed to the second connection.

2. The robot according to claim 1, wherein the first base piece and the second base piece are connected by screws.

3. The first connecting portion includes a first bearing portion through which the shaft is inserted, and a first bearing holding portion that holds the first bearing portion. The first base piece is fixed to the first bearing retaining portion. The second connecting portion has a second bearing portion through which the shaft is inserted, and a second bearing holding portion that holds the second bearing portion. The robot according to claim 1, wherein the second base piece is fixed to the second bearing retaining portion.

4. The robot according to claim 3, wherein the first bearing portion and the second bearing portion are each deep groove ball bearings.

5. A third arm is connected to the second arm and rotates around a third axis of rotation parallel to the second axis of rotation relative to the second arm, A first link connected to the shaft, whose orientation is kept constant regardless of the orientation of the first arm and the second arm, It has a second link that connects the position of the first link offset from the second rotation axis and the position of the third arm offset from the third rotation axis, The robot according to claim 1, wherein the third arm is maintained in a constant position regardless of the positions of the first arm and the second arm.

6. The robot according to claim 5, wherein the first link is connected to the shaft in the portion between the first connection and the second connection.

7. In a plan view from a direction perpendicular to the direction along the second rotation axis and the direction in which the second rotation axis and the third rotation axis are aligned, The robot according to claim 5, wherein the second link overlaps with the second arm.

Images