Arm robot

Abstract

The wrist portion (4) of the arm robot is provided with a first motor (31), a first speed reducer (35), a second motor (41), a transmission shaft (45), and a second speed reducer (46). The first motor (31) is arranged at the base end portion (21) and generates a first rotation driving force for rotating the first front end portion (23a). The first speed reducer (35) is arranged at the first front end portion (23a), has a hollow portion, and reduces the rotation speed of the first rotation driving force. The second motor (41) is arranged at the base end portion (21) and generates a second rotation driving force for rotating the second front end portion (23b). The transmission shaft (45) is arranged at the first front end portion (23a) and penetrates the hollow portion of the first speed reducer (35). The second speed reducer (46) is arranged at the first front end portion (23a) and is coaxial with and arranged in the axial direction of the first speed reducer (35).

Description

Technical Field

[0001] This invention mainly relates to an arm robot with an arm and a wrist. Background Technology

[0002] Patent document 1 discloses a robot having an A arm, a B arm, and a C arm. The B arm is cantilevered and supported by the A arm. The C arm is connected to the B arm. An end effector is mounted on the C arm. The A, B, and C arms are each driven independently. Within the A arm, a B motor for driving the B arm and a C motor for driving the C arm are disposed. The rotational driving force of the B motor can be reduced by a B reducer disposed within the B arm. The rotational driving force of the C motor can be reduced by a C reducer disposed within the B arm. The shaft of the B reducer is aligned with the rotational axis of the B arm. The shaft of the C reducer is aligned with the rotational axis of the C arm.

[0003] [Existing Technical Documents]

[0004] [Patent Documents]

[0005] Patent Document 1: Japanese Patent Application Publication No. 2019-84608 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] In the structure of Patent Document 1, since the B reducer and the C reducer are configured to face different directions, at least one of the B arm and the C arm can be easily enlarged. Here, the portion where the A arm, B arm, and C arm are combined is referred to as the wrist.

[0008] This application was made in view of the above circumstances, and its main purpose is to provide a compact arm robot with a cantilever wrist end.

[0009] Solution for solving the problem

[0010] The technical problem to be solved by this application is as described above. The technical solution used to solve the technical problem and its effects are described below.

[0011] Based on the viewpoint of this application, an arm robot with the following structure is provided. That is, the arm robot has an arm portion and a wrist portion connected to the arm portion. The wrist portion has a base end portion, a connecting portion, a first front end portion, a second front end portion, a first motor, a first reducer, a second motor, a transmission shaft, and a second reducer. The base end portion is connected to the arm portion. The connecting portion extends from the base end portion to a front end side. The first front end portion is disposed further forward than the base end portion and is cantilevered and supported on the base end portion by the connecting portion, and is rotatably mounted on the base end portion. The second front end portion is rotatably connected relative to the first front end portion and can be fitted with an end effector. The first motor is disposed at the base end portion and generates a first rotational driving force for rotating the first front end portion. The first reducer is disposed at the first front end portion and has a hollow portion to reduce the rotational speed of the first rotational driving force. The second motor is disposed at the base end portion and generates a second rotational driving force for rotating the second front end portion. The transmission shaft is disposed at the first front end portion and extends through the hollow portion of the first reducer. The second reducer is disposed at the first front end, coaxial with the first reducer and arranged axially, and transmits the second rotational driving force via the transmission shaft, reducing the rotational speed of the second rotational driving force and transmitting it to the second front end.

[0012] Thus, by arranging the first and second reducers axially, the front end of the cantilever-supported wrist (the part consisting of the first and second front ends) can be made compact.

[0013] The effects of the invention

[0014] Based on the present invention, a compact arm robot with a cantilevered wrist support at the front end can be provided. Attached Figure Description

[0015] Figure 1 This is a perspective view of an arm robot according to one embodiment of this application.

[0016] Figure 2 This is a side view of the wrist.

[0017] Figure 3 It is a cross-sectional view showing the power transmission in the front part of the wrist. Detailed Implementation

[0018] The embodiments of this application will now be described with reference to the accompanying drawings. First, referring to... Figure 1 The outline of the arm robot 1 is described below.

[0019] The robotic arm 1 is an industrial robot installed in factories and other work environments. An end effector 5 is mounted at the front end of the robotic arm 1. The robotic arm 1 uses the end effector 5 to perform tasks. Tasks performed by the robotic arm 1 include, for example, assembly, welding, painting, and washing.

[0020] The arm robot 1 is a teach-and-reproduce type. The teach-and-reproduce type refers to a system where the operator manually instructs the arm robot 1 on its movements and tasks beforehand, allowing the arm robot 1 to repeatedly perform the taught movements and tasks. Alternatively, the arm robot 1 can also be of a type other than the teach-and-reproduce type.

[0021] like Figure 1 As shown, the robotic arm 1 comprises a base 2, an arm 3, and a wrist 4. The base 2 is fixed in a suitable location at the work site, such as a floor, ceiling, or support platform. The base of the arm 3 is connected to the base 2, and the tip of the arm 3 is connected to the wrist 4. The base of the wrist 4 is connected to the arm 3, and an end effector 5 can be installed at the tip of the wrist 4.

[0022] The arm portion 3 includes a first movable portion 11, a second movable portion 12, and a third movable portion 13. The first movable portion 11 is rotatably connected to the base 2. The first movable portion 11 can rotate relative to the base 2 about a first rotation axis 101. The second movable portion 12 is rotatably connected to the first movable portion 11. The second movable portion 12 can rotate relative to the first rotation axis 101 about a second rotation axis 102. Furthermore, the first rotation axis 101 and the second rotation axis 102 are perpendicular. The third movable portion 13 is rotatably connected to the second movable portion 12. The third movable portion 13 can rotate relative to the second movable portion 12 about a third rotation axis 103. The third rotation axis 103 is perpendicular to the first rotation axis 101 and parallel to the second rotation axis 102.

[0023] The robotic arm 1 is equipped with motors for driving the first movable part 11, the second movable part 12, and the third movable part 13. In addition, the arm 3 is equipped with encoders for detecting the rotation of the first movable part 11, the second movable part 12, and the third movable part 13.

[0024] The wrist portion 4 includes a base end portion 21, a connecting portion 22, and a front end portion 23. The base end portion 21 is rotatably connected to the arm portion 3 (third movable portion 13). The base end portion 21 can rotate relative to the arm portion 3 (third movable portion 13) about a fourth rotation axis 104 by generating a rotational driving force with a motor (not shown). In addition, a first motor 31 and a second motor 41 are disposed inside the base end portion 21.

[0025] The connecting portion 22 connects the base end portion 21 to the front end portion 23. The front end portion 23 is cantilevered to the base end portion 21 via the connecting portion 22. Specifically, the connecting portion 22 is connected only to one end of the base end portion 21 in a predetermined direction (in this embodiment, the direction perpendicular to the fourth rotation axis 104, specifically the direction parallel to the fifth rotation axis 105), and similarly, the connecting portion 22 is connected only to one end of the front end portion 23 in a predetermined direction. Furthermore, "support on both sides" refers to a structure in which the two ends of the base end portion 21 and the front end portion 23 are connected to each other via the connecting portion. Because the front end portion 23 is cantilevered (single-sided support), the wrist portion 4 can be made compact.

[0026] The front end portion 23 utilizes the first rotational driving force generated by the first motor 31 to rotate relative to the base end portion 21 and the connecting portion 22 with the fifth rotation axis 105 as the rotation center. The transmission of the first rotational driving force will be described later.

[0027] The front end portion 23 has a first front end portion 23a and a second front end portion 23b. The first front end portion 23a is located further to the base end side than the second front end portion 23b. Therefore, the first front end portion 23a is rotatably connected to the connecting portion 22. The second front end portion 23b is rotatably connected to the first front end portion 23a. The second front end portion 23b rotates relative to the first front end portion 23a about the sixth rotation axis 106 using a second rotational driving force generated by the second motor 41. The transmission of the second rotational driving force will be described later.

[0028] The fourth rotation axis 104 is parallel to the sixth rotation axis 106, and in this embodiment, they are aligned. Furthermore, the fifth rotation axis 105 is perpendicular to the fourth rotation axis 104 (and the sixth rotation axis 106). Additionally, the rotation of each part of the wrist 4 is detected by an encoder (not shown in the diagram).

[0029] Thus, the arm robot 1 in this embodiment is a six-axis vertical multi-joint type. However, the number of joints or the direction of the rotation axis may differ from this embodiment.

[0030] Below, refer to Figure 2 The structure of the wrist 4, especially the transmission of the first and second rotational driving forces, is described in detail.

[0031] As described above, a first motor 31 is disposed in the base end portion 21. A first base end pulley 32 is mounted on the output shaft of the first motor 31. A first belt 33 is wound around the first base end pulley 32. The first belt 33 passes through the interior of the connecting portion 22 and transmits the first rotational driving force to the front end portion 23.

[0032] A first front pulley 34 and a first reducer 35 are disposed in the front end portion 23 (first front end portion 23a). The first front pulley 34 and the first reducer 35 are coaxial. Coaxial means that the positions of the axes of the various components (the positions of the straight lines passing through the center of the circular component) are the same. A first belt 33 is wound around the first front pulley 34. The first front pulley 34 is connected to the first reducer 35 in a state that can transmit the first rotational driving force. A hollow portion is formed around the position of the axis of the first reducer 35. The first reducer 35 reduces the rotational speed of the transmitted first rotational driving force.

[0033] Based on this structure, the first rotational driving force transmitted to the front end 23 is transmitted to the first reducer 35 via the first front pulley 34. Furthermore, the first reducer 35 is connected to the base portion (the rotating base 64 described later) for rotating the front end 23 in a state capable of transmitting the first rotational driving force. Thus, the front end 23 can be rotated at a speed reduced by the first reducer 35.

[0034] As described above, a second motor 41 is disposed in the base end portion 21. A second base end pulley 42 is mounted on the output shaft of the second motor 41. A second belt 43 is wound around the second base end pulley 42. The second belt 43 passes through the interior of the connecting portion 22 and transmits the second rotational driving force to the front end portion 23.

[0035] The first motor 31 and the second motor 41 are arranged side by side along the length direction of the wrist portion 4. The wrist length direction is the direction that connects the base end portion 21 to the front end portion 23, for example, a direction parallel to the fourth rotation axis 104 or the sixth rotation axis 106. Based on this structure, the length of the connecting portion 22 can be reduced, thereby improving rigidity. In this embodiment, the first motor 31 is configured to be further forward than the second motor 41. However, the first motor 31 may also be configured to be further forward than the second motor 41.

[0036] The direction perpendicular to the length of the wrist, and parallel to the fifth rotation axis 105, is called the wrist axis. The positions of the first motor 31 and the second motor 41 in the wrist axis are only slightly different. Thus, because the positions of the first belt 33 and the second belt 43 in the wrist axis are different, interference between the first belt 33 and the second belt 43 can be prevented. However, it is also possible for the first motor 31 and the second motor 41 to be in the same position along the length of the wrist. In this case, for example, it is sufficient to use a power transmission component to offset the position of the first belt 33 or the second belt 43.

[0037] At the front end portion 23 (first front end portion 23a), a second front pulley 44, a transmission shaft 45, and a second reducer 46 are disposed. The second front pulley 44, transmission shaft 45, and second reducer 46 are coaxial. Furthermore, these components are also coaxial with the first front pulley 34 and the first reducer 35. A second belt 43 is wound around the second front pulley 44. The second front pulley 44 is connected to one end of the transmission shaft 45 in a manner capable of transmitting a second rotational driving force. The transmission shaft 45 is configured to pass through the hollow portion of the first reducer 35. The other end of the transmission shaft 45 is connected to the second reducer 46 in a manner capable of transmitting the second rotational driving force. The second reducer 46 reduces the rotational speed of the second rotational driving force.

[0038] Based on this structure, the second rotational driving force transmitted to the front end 23 is transmitted to the second reducer 46 via the second front pulley 44 and the transmission shaft 45. Furthermore, the second reducer 46 is connected to the first gear component 52 in a state capable of transmitting the second rotational driving force. The first gear component 52 and the meshing second gear component 53 are configured as bevel gears, transmitting the second rotational driving force with a 90-degree change in direction. The second gear component 53 is connected to a portion of the second front end 23b (the end effector mounting portion 65, which rotates integrally with the end effector 5) in a state capable of transmitting the second rotational driving force. Thus, the second front end 23b can be rotated at a speed reduced by the second reducer 46.

[0039] In this embodiment, the first reducer 35 and the second reducer 46 are arranged side by side along the wrist axis. Therefore, space can be utilized effectively, resulting in a compact front end 23 along the wrist axis. Consequently, the radius of rotation when the wrist 4 rotates about the fourth rotation axis 104 can be reduced.

[0040] Furthermore, in this embodiment, when the first reducer 35 and the second reducer 46 are viewed from a direction perpendicular to the axial direction (i.e., Figure 2 In the first reducer 35, the first reducer 35 overlaps with the second reducer 46. In other words, the hollow portion of the first reducer 35 contains not only the transmission shaft 45 but also the second reducer 46. This structure allows the front end 23 to be more compact in the wrist axis. However, the overlap of the first reducer 35 and the second reducer 46 is not an essential feature; it is also possible for the first reducer 35 and the second reducer 46 to be separate when viewed in a direction perpendicular to the axial direction.

[0041] Furthermore, in this embodiment, the first motor 31 and the second motor 41 are substantially aligned in the height direction (parallel to the first rotation axis 101). In other words, when viewed from the direction parallel to the fourth rotation axis 104, the first motor 31 and the second motor 41 overlap. If the first motor 31 and the second motor 41 are not aligned in the height direction, the dimension of the base end portion 21 in the height direction will increase. Furthermore, since the first base pulley 32 and the second base pulley 42 are not aligned in the height direction, the paths of the first belt 33 and the second belt 43 will form a V-shape, and the dimension of the connecting portion 22 in the height direction may also increase. In this embodiment, since the first motor 31 and the second motor 41 are substantially aligned in the height direction, the dimensions of the base end portion 21 and the connecting portion 22 in the height direction can be reduced.

[0042] Below, refer to Figure 3 The structure for transmitting the first rotational driving force and the second rotational driving force will be described in more detail.

[0043] First, the structure for transmitting the first rotational driving force will be explained. As described above, the first rotational driving force generated by the first motor 31 is transmitted to the first reducer 35 through the first belt 33 and the first front pulley 34. The first reducer 35 is a wave gear device, consisting of an input component (wave generator) 35a, an output component (flexible wheel) 35b, and a fixed component (annular spline) 35c.

[0044] The input component 35a is a component with a bearing assembled on the outer periphery of an elliptical cam. A through hole is formed at the center of the elliptical cam (the part through which the fifth rotation axis 105 passes and its vicinity), thus forming a hollow portion. The inner wheel of the bearing is fixed to the elliptical cam, but the outer wheel is elastically deformed by a ball bearing. The input component 35a is fixed to the first front pulley 34 by bolts or other suitable components, and the input component 35a rotates integrally with the first front pulley 34.

[0045] The output component 35b is an approximately cylindrical component. Because it has an opening at its center and near the center, the output component 35b has a hollow portion. The output component 35b is relatively thin (for example, thinner than the input component 35a and the fixing component 35c), making it prone to elastic deformation. At one end in the axial direction ( Figure 3 At its upper end, the output component 35b contacts the outer wheel of the bearing of the input component 35a. Therefore, the output component 35b deforms into an elliptical shape due to the force exerted by the input component 35a. Additionally, at one end of the output component 35b in the axial direction ( Figure 3The upper end of the output component 35b, near the side of the second front end portion 23b, also contacts the fixing member 35c. Specifically, teeth are formed on the outer periphery of the output component 35b, which mesh with the teeth on the inner periphery of the fixing member 35c. The other axial end of the output component 35b ( Figure 3 The lower end is configured as a flange shape (extending radially).

[0046] The fixing member 35c is an annular member with teeth formed on its inner circumference. Furthermore, the number of teeth on the inner circumference of the fixing member 35c is a predetermined number (e.g., two) more than the number of teeth on the outer circumference of the output member 35b. The output member 35b is fixed to the housing member 61 at the front end 23 in a way that prevents relative rotation.

[0047] Thus, any one of the input component 35a, the output component 35b, and the fixed component 35c has an opening at or near the center, thereby forming a hollow portion on the first reducer 35.

[0048] Since the wave gear mechanism is well-known, the principle of speed reduction will only be briefly explained. Specifically, the output component 35b is elastically deformed into an ellipse by the input component 35a. At this time, at the end of the major axis of the ellipse, the output component 35b meshes with the teeth of the fixed component 35c; at the end of the minor axis of the ellipse, the output component 35b disengages from the teeth of the fixed component 35c. Therefore, by rotating the input component 35a, the meshing position of the teeth gradually changes. Thus, for every revolution of the input component 35a in the first direction, the output component 35b rotates in the second direction (opposite to the first direction) by an amount equivalent to the difference in the number of teeth between the output component 35b and the fixed component 35c. Therefore, the rotational speed input to the input component 35a can be reduced and output from the output component 35b.

[0049] At the front end 23, a rotating base 64 and a crossed roller bearing 63 are provided.

[0050] The rotating base 64 is a component that supports the rotation of the relative outer shell member 61 in the front end 23 (e.g., the second front end 23b, and the component that transmits the second rotational driving force to the second front end 23b).

[0051] The crossed roller bearing 63 connects a component fixed to the housing member 61, etc., to a component that rotates relative to the housing member 61, etc. Specifically, the crossed roller bearing 63 includes an inner wheel 63a and an outer wheel 63b. The inner wheel 63a is fixed to the housing member 61 without relative rotation by a fixing member 35c. The outer wheel 63b, together with the flange portion of the output member 35b, is fixed to the rotating base 64 without relative rotation. In other words, the outer wheel 63b, the output member 35b, and the rotating base 64 can rotate as a single unit. Based on the above structure, the first rotational driving force can be reduced, and the front end 23 can rotate about the fifth rotation axis 105 as the rotation center.

[0052] The structure for transmitting the second rotational driving force will now be described. As described above, the second rotational driving force generated by the second motor 41 is transmitted to the transmission shaft 45 via the second belt 43 and the second front pulley 44. The transmission shaft 45 is configured to pass through the hollow portion of the first reducer 35. Specifically, the transmission shaft 45 passes through the overlapping portion of the input component 35a, the output component 35b, and the fixing component 35c, and the front end of the transmission shaft 45 (the end near the second front end portion 23b) is located in front of the flange-shaped portion of the output component 35b. That is, a portion of the second reducer 46 enters the hollow portion of the output component 35b of the first reducer 35. Therefore, the figure viewed from the direction perpendicular to the axial direction ( Figure 3 In the first reducer 35, the second reducer 46 overlaps.

[0053] The second reducer 46 is a wave gear device, consisting of an input component (wave generator) 46a, an output component (flexible gear) 46b, and a fixed component (annular spline) 46c. The structure and principle of the second reducer 46 for reducing the second rotational speed are the same as those of the first reducer 35, therefore, related descriptions are omitted.

[0054] The transmission shaft 45 is fixed to the input component 46a by bolts or the like, preventing relative rotation. The output component 46b is not cylindrical, but cup-shaped with a bottom. The first gear component 52 is fixed to the bottom of the output component 46b by the connecting member 51, preventing relative rotation. The fixing component 46c is fixed to the rotating base 64 by bolts or the like, preventing relative rotation.

[0055] Therefore, the first gear component 52 can rotate at a rotational speed reduced by the second reducer 46. As described above, the first gear component 52 meshes with the second gear component 53, and the connecting member 51 and the first gear component 52 are configured as bevel gears. In addition, the end effector mounting portion 65 is fixed to the second gear component 53 by bolts or the like so that it cannot rotate relative to the first gear component 53.

[0056] Based on the above structure, the second rotational driving force can be reduced, and the second front end 23b can rotate around the sixth rotation axis 106 as the rotation center.

[0057] As described above, the robotic arm 1 of this embodiment includes an arm portion 3 and a wrist portion 4 connected to the arm portion 3. The wrist portion 4 includes a base end portion 21, a connecting portion 22, a first front end portion 23a, a second front end portion 23b, a first motor 31, a first reducer 35, a second motor 41, a transmission shaft 45, and a second reducer 46. The base end portion 21 is connected to the arm portion 3. The connecting portion 22 extends from the base end portion 21 to the front end side. The first front end portion 23a is configured to be further forward than the base end portion 21 and is cantilevered on the base end portion 21 by the connecting portion 22, and is rotatably mounted on the base end portion 21. The second front end portion 23b is rotatably connected to the first front end portion 23a and can be fitted with an end effector 5. The first motor 31 is disposed at the base end portion 21 and generates a first rotational driving force for rotating the first front end portion 23a. The first reducer 35 is disposed at the first front end portion 23a and has a hollow portion to reduce the rotational speed of the first rotational driving force. A second motor 41 is disposed at the base end 21, generating a second rotational driving force for rotating the second front end 23b. A transmission shaft 45 is disposed at the first front end 23a, passing through the hollow portion of the first reducer 35. A second reducer 46 is disposed at the first front end 23a, coaxial with and axially arranged with the first reducer 35, and receives the second rotational driving force through the transmission shaft 45, reducing the rotational speed of the second rotational driving force before transmitting it to the second front end 23b.

[0058] Thus, by arranging the first reducer 35 and the second reducer 46 side by side along the axial direction, the front end 23 can be compacted at the wrist portion 4 of the cantilever support.

[0059] In the arm robot 1 of this embodiment, at least a portion of the second reducer 46 is disposed in the hollow portion of the first reducer 35, and when viewed from a direction perpendicular to the axial direction, the first reducer 35 and the second reducer 46 overlap.

[0060] This allows for a more concentrated configuration of the first reducer 35 and the second reducer 46, thereby enabling a more compact front end 23 of the wrist portion 4.

[0061] In the arm robot 1 of this embodiment, the first motor 31 and the second motor 41 are arranged side by side along the length of the wrist.

[0062] Therefore, compared with the structure in which the first motor 31 and the second motor 41 are arranged along the height direction, the dimension of the base end 21 in the height direction can be reduced.

[0063] The preferred embodiments of this application have been described above, but the above structure can be modified in the following ways.

[0064] In the above embodiments, both the first reducer 35 and the second reducer 46 are wave gear devices, but they can also be reducers with different structures.

[0065] In the above embodiments, the positions of the first motor 31 and the second motor 41 in the height direction are basically the same, but the positions of the first motor 31 and the second motor 41 in the height direction can also be quite different.

Claims

1. An arm robot comprising an arm and a wrist connected to the arm, characterized in that: The wrist portion has: The base end attached to the arm portion; The connecting portion extends from the base end to the front end; A first front end portion is disposed on the front end side further than the base end portion, cantilevered on the base end portion by the connecting portion, and rotatably mounted on the base end portion; A second front end that is rotatably connected to and on which an end effector can be mounted relative to the first front end; A first motor is disposed at the base end and generates a first rotational driving force for rotating the first front end; A first speed reducer disposed at the first front end, having a hollow portion, and reducing the rotational speed of the first rotational driving force; A second motor is configured at the base end to generate a second rotational driving force for rotating the second front end; A transmission shaft disposed at the first front end and passing through the hollow portion of the first reducer; as well as The second reducer is configured at the first front end, coaxial with the first reducer and arranged along the axial direction, and connected to the front end of the transmission shaft. The second rotational driving force is transmitted through the transmission shaft, and the rotational speed of the second rotational driving force is reduced and then transmitted to the second reducer at the second front end. The second reducer is connected to the first gear component in a state capable of transmitting the second rotational driving force. The first gear component and the second gear component meshing with the first gear component are configured as bevel gears, so that the direction of the second rotational driving force is changed by 90 degrees. At least a portion of the second reducer is disposed in the hollow portion of the first reducer, and when viewed from a direction perpendicular to the axial direction, the first reducer and the second reducer overlap.

2. The robotic arm as described in claim 1, characterized in that: When the length direction of the connecting part is referred to as the wrist length direction, the first motor and the second motor are arranged side by side in the wrist length direction.

Images