Robot

Abstract

To provide a robot of which down-sizing can be achieved.SOLUTION: A robot comprises: a base installed on a robot installation surface; a first arm having a base end part and a tip, the base end part being so connected to the base as to be rotatable around a first rotation axis via a first joint part; a second arm which is so connected to the tip of the first arm as to be rotatable around a second rotation axis parallel to the first rotation axis via a second joint part; and a shaft which is so connected to the second arm as to be movable along a third rotation axis parallel to the first rotation axis. The first joint part has a first speed reducer, the second joint part has a second speed reducer, and at least one of the first speed reducer and the second speed reducer is a planetary gear type speed reducer. The first arm has a ramp in which the tip thereof is inclined as to be nearer to the robot installation surface than the base end part.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a robot. [Background technology]

[0002] For example, as shown in Patent Document 1, there is known a robot that has a robot arm equipped with multiple arms and joints that rotatably connect adjacent arms, and that drives the robot arms to assume a desired posture to perform tasks such as transport, assembly, and processing on a workpiece. The robot arm has multiple joints, and each joint is provided with a joint mechanism as a drive unit for driving the arm to rotate. The joint mechanism has a motor as a drive source and a reducer that reduces the rotational speed of the motor.

[0003] In Patent Document 1, a planetary gear type reducer is used as the reducer, which can reduce backlash between the gears and improve the positioning accuracy of the robot arm. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-222116 Summary of the Invention [Problem to be solved by the invention]

[0005] However, planetary gear reducers are relatively large, and the lengths of the input and output shafts extending vertically of the planetary gear reducer are particularly long, which increases the overall height of the robot and leads to an increase in the size of the robot. This increases the size of the robot, which can result in restrictions on the installation location and conditions, the type of work, the work content, and the working conditions of the robot. [Means for solving the problem]

[0006] The robot of the present invention comprises: a base that is installed on a robot installation surface; a first arm having a base end and a tip end, the base end being connected to the base via a first joint portion so as to be rotatable around a first rotation axis; a second arm connected to the tip end of the first arm via a second joint portion so as to be rotatable around a second rotation axis parallel to the first rotation axis; a shaft connected to the second arm so as to be movable along a third rotation axis parallel to the first rotation axis, the first joint portion has a first reducer, the second joint portion has a second reducer, and at least one of the first reducer and the second reducer is a planetary gear type reducer; The first arm has an inclined portion that is inclined so that the tip end is closer to the robot installation surface than the base end.

[0007] The robot of the present invention comprises: a base that is installed on a robot installation surface; a first arm having a base end and a tip end, the base end being connected to the base via a first joint portion so as to be rotatable around a first rotation axis; a second arm connected to the tip end of the first arm via a second joint portion so as to be rotatable around a second rotation axis parallel to the first rotation axis; a shaft connected to the second arm so as to be movable along a third rotation axis parallel to the first rotation axis, the first joint portion has a first reducer, the second joint portion has a second reducer, and at least one of the first reducer and the second reducer is a planetary gear type reducer; The first arm has a step portion between the base end and the tip end, the height of which changes in the first rotation axis direction, and the tip end is closer to the robot installation surface than the base end. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a side view showing a schematic configuration of a robot according to a first embodiment of the present invention. [Figure 2]FIG. 2 is a cross-sectional view of a first reducer included in the robot shown in FIG. [Figure 3] FIG. 3 is a perspective view showing the internal structure of the first reducer shown in FIG. 2. [Figure 4] FIG. 2 is a side view of the first arm shown in FIG. [Figure 5] FIG. 10 is a perspective view showing the internal structure of a first reducer included in a robot according to a second embodiment of the present invention. [Figure 6] FIG. 10 is a side view of a first arm included in a robot according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A robot according to the present invention will now be described in detail with reference to the embodiments shown in the accompanying drawings. First Embodiment Fig. 1 is a side view showing a schematic configuration of a robot system according to a first embodiment of the present invention. Fig. 2 is a cross-sectional view of a first reducer provided in the robot shown in Fig. 1. Fig. 3 is a perspective view showing an internal structure of the first reducer shown in Fig. 2. Fig. 4 is a side view of a first arm shown in Fig. 1.

[0010] The up-down direction in Fig. 1 corresponds to the vertical direction, and the upper side in Figs. 1, 3, and 4 is also referred to as "upper," and the lower side as "lower." With regard to the robot arm 72, the first arm 73, and the second arm 74, the right side in Figs. 1 and 4 is referred to as the "base end" or "base end side," and the left side is referred to as the "tip end" or "tip end side." The same applies to Figs. 5 and 6.

[0011] In this specification, "vertical" refers not only to the case where the object is perpendicular to the vertical, but also to the case where the object is slightly tilted from the vertical, for example, within ±10°. In this specification, "parallel" refers not only to the case where two objects are parallel to each other, but also to the case where the object is slightly tilted from the vertical, for example, within ±10°.

[0012] The robot system 1 shown in FIG. 1 includes a robot 7 and a control device 6 that controls the driving of each part of the robot 7.

[0013] The robot 7 in this embodiment is a scalar robot, and is used for tasks such as holding, transporting, assembling, processing, painting, and inspecting workpieces such as electronic components (hereinafter these are collectively referred to as "tasks"). However, the use of the robot 7, the type of task, the task content, the task conditions, etc. are not particularly limited. Furthermore, the robot 7 may be a robot other than a scalar robot, such as a six-axis articulated robot or a dual-arm robot.

[0014] As shown in FIG. 1, the robot 7 has a base 71 and a robot arm 72 rotatably connected to the base 71.

[0015] The base 71 is installed on a robot installation surface 100, which is, for example, the floor of a factory workroom. This robot installation surface 100 is a horizontal surface. However, the robot installation surface 100 is not limited to this configuration, and may be, for example, a wall surface, ceiling, top surface of a stand, or floor surface of a mobile table of the workroom. If the robot installation surface 100 is a wall surface of the workroom, the robot installation surface 100 will be a vertical surface that is perpendicular to the horizontal plane.

[0016] The robot arm 72 has a first arm 73 rotatably connected to the base 71 around a first rotation axis J1, a second arm 74 rotatably connected to the first arm 73 around a second rotation axis J2, and a work head 75 rotatably connected to the second arm 74 around a third rotation axis J3 and movable in the axial direction (up and down) of the third rotation axis J3.

[0017] The first arm 73 has an elongated shape and has a base end 73A and a tip end 73B. The base end 73A is connected to the base 71. The first arm 73 rotates around a first rotation axis J1 that is perpendicular to the base 71.

[0018] The second arm 74 has a longitudinal shape extending in the lateral direction (horizontal direction) in Figure 1, and has a base end 74A and a tip end 74B. The base end 74A of the second arm 74 is connected to the tip end 73B of the first arm 73. The second arm 74 rotates around a second rotation axis J2 that is perpendicular to the first arm 73.

[0019] FIG. 1 shows the reference posture (home position) of the robot arm 72, and in this reference posture, the longitudinal direction of the first arm 73 and the longitudinal direction of the second arm 74 are parallel to each other.

[0020] In the reference position of the robot arm 72, the first rotation axis J1, the second rotation axis J2, and the third rotation axis J3 are parallel, but even when the robot arm 72 is driven to perform a desired operation and its position is changed from the reference position, the first rotation axis J1, the second rotation axis J2, and the third rotation axis J3 remain parallel.

[0021] A work head 75 is provided on the tip 74B of the second arm 74. The work head 75 has a spline nut 751 and a ball screw nut 752 that are coaxially arranged on the tip 74B of the second arm 74, and a spline shaft 753 that is inserted through the spline nut 751 and the ball screw nut 752. The spline shaft 753 is rotatable relative to the second arm 74 around a third rotation axis J3 that is its central axis and extends along the vertical direction, and is also movable up and down in a direction along the third rotation axis J3.

[0022] An end effector 76 is attached to the lower end of the spline shaft 753. The end effector 76 has a function of holding, for example, a workpiece or a tool for machining the workpiece. The end effector 76 is detachable from the spline shaft 753, and an end effector suitable for the intended work is selected and attached as appropriate.

[0023] The robot arm 72 has a first joint 2K, a second joint 3K, a third joint 4K, and a fourth joint 5K.

[0024] The first joint portion 2K rotatably connects the first arm 73 to the base 71, and has a motor unit 2 that rotates the first arm 73 relative to the base 71 around a first rotation axis J1.

[0025] The second joint portion 3K rotatably connects the second arm 74 to the first arm 73, and has a motor unit 3 that rotates the second arm 74 relative to the first arm 73 around a second rotation axis J2.

[0026] The third joint portion 4K connects the spline shaft 753 to the second arm 74 so that it can be raised and lowered along the third rotation axis J3, and has a first drive mechanism 4 that rotates the ball screw nut 752 to raise and lower the spline shaft 753 in a direction along the third rotation axis J3.

[0027] The fourth joint portion 5K connects the spline shaft 753 to the second arm 74 so that it can rotate around the third rotation axis J3, and has a second drive mechanism 5 that rotates the spline nut 751 to rotate the spline shaft 753 around the third rotation axis J3.

[0028] The motor unit 2 has a motor 21 and a power transmission mechanism 22 that uses the motor 21 as a drive source. The motor 21 generates a drive force that rotates the first arm 73 relative to the base 71.

[0029] The motor unit 3 has a motor 31 and a power transmission mechanism 32 that uses the motor 31 as a drive source. The motor 31 generates a drive force that rotates the second arm 74 relative to the first arm 73.

[0030] The first drive mechanism 4 has a motor 41 and a power transmission mechanism 42 that uses the motor 41 as a drive source. The motor 41 generates a drive force that rotates the ball screw nut 752 to raise and lower the spline shaft 753 in the direction along the third rotation axis J3.

[0031] The second drive mechanism 5 has a motor 51 and a power transmission mechanism 52 that uses the motor 51 as a drive source. The motor 51 generates a drive force that rotates the spline nut 751 to rotate the spline shaft 753 about the third rotation axis J3.

[0032] Motors 21, 31, 41, and 51 are not particularly limited, and examples thereof include servo motors such as AC servo motors and DC servo motors. Motors 21, 31, 41, and 51 are each equipped with a motor driver for driving the motor according to the type and specifications of the motor.

[0033] Although not shown, motors 21, 31, 41, and 51 each include a stator, a rotor that rotates inside the stator, and a case that houses these components. The stator is arranged along the inner circumference of the case and has windings, such as three-phase windings. The stator generates a magnetic field when current, for example, three-phase AC current, is passed through the windings. In motors 21, 31, 41, and 51, the current flow pattern, current flow timing, current amount, and the like, for each winding of the stator are controlled by control device 6. As a result, motors 21, 31, 41, and 51 rotate with the desired timing, direction, and speed, respectively.

[0034] The power transmission mechanism 22 has a first reducer 23A. The power transmission mechanism 32 has a second reducer 23B. The power transmission mechanism 42 has a pulley and a belt (not shown). The power transmission mechanism 52 has a pulley and a belt (not shown).

[0035] The first reducer 23A and the second reducer 23B are each a planetary gear type reducer. Since the first reducer 23A and the second reducer 23B have the same configuration, the first reducer 23A will be representatively described below.

[0036] As shown in Figures 2 and 3, the first reducer 23A has a casing 231, an internal gear 233, a sun gear 234, multiple planetary gears 235 (three in this embodiment), a carrier 236, an input shaft 237, and an output shaft 238. In Figure 3, the input shaft 237 and the output shaft 238 are illustrated thinner than they actually are to make the internal structure easier to see. This also applies to Figure 4. The first reducer 23A may have an elastic support member on the outside of the internal gear 233. The elastic support member allows radial deformation of the internal gear 233 due to the action of stress, and has strength sufficient to prevent phase shift in the circumferential direction relative to the casing 231.

[0037] As shown in FIG. 2, the casing 231 is a cylindrical casing that functions to protect each component therein.

[0038] 3, the internal gear 233 has a ring or cylindrical shape with the axis O1 as its central axis, and has internal teeth 233A on its inner periphery. The internal teeth 233A mesh with the teeth 235A of each planetary gear 235.

[0039] The sun gear 234 has teeth 234A on its outer periphery and is disposed inside the internal gear 233 and concentrically therewith. The sun gear 234 is connected to an input shaft 237 and rotates around an axis O1. The input shaft 237 is connected to the rotating shaft of the motor 21, for example, via a bearing (not shown). The motor 21 is fixed to the base 71 directly or indirectly, although not shown.

[0040] The three planetary gears 235 are arranged at equal angular intervals from one another on the outer circumferential side of the sun gear 234 and on the inner circumferential side of the internal gear 233. Each planetary gear 235 has teeth 235A on its outer periphery, which mesh with teeth 234A of the sun gear 234 and internal teeth 233A of the internal gear 233. The three planetary gears 235 each have the same diameter and the same number of teeth 235A.

[0041] As shown in FIGS. 2 and 3, the gear train of the sun gear 234 and the three planetary gears 235 is provided in a single row on the same plane, that is, on a predetermined cross section of the first reducer 23A.

[0042] Furthermore, there are no particular limitations on the types, shapes, etc. of the internal gear 233, sun gear 234, and planetary gears 235, and in the illustrated configuration, they are all spur gears. However, in the present invention, it is preferable that the internal gear 233, sun gear 234, and planetary gears 235 are each helical gears.

[0043] 3, carrier 236 supports planetary gear 235 so as to be rotatable around axis O2, which is the central axis of planetary gear 235. In the illustrated configuration, carrier 236 has a so-called star shape, in which three rod-shaped members arranged at 120° intervals are connected at their ends on the axis O1 side. However, the configuration is not limited to this, and carrier 236 may be formed of, for example, a frame-shaped member or a disk-shaped member.

[0044] An output shaft 238 is connected to the center of the carrier 236. The output shaft 238 is fixed to the base end portion 73A of the first arm 73 via, for example, a bearing (not shown).

[0045] The rotational force transmitted from the motor 21 is transmitted to the sun gear 234 via the input shaft 237, causing the sun gear 234 to rotate in a predetermined direction around the axis O1. When the sun gear 234 rotates, each planetary gear 235 rotates (spins) around the axis O2 while rotating (revolves) around the axis O1. The revolution of each planetary gear 235 around the axis O1 causes the carrier 236 to rotate around the axis O1, and the output shaft 238 to rotate around the axis O1. As a result, the rotation of the output shaft 238 is reduced by the planetary gears 235 and is slower than the rotation of the input shaft 237. Therefore, the rotational speed of the input shaft 237 is reduced and output from the output shaft 238. As a result, the first arm 73 can rotate relative to the base 71 at a reduced speed, and the rotational torque of the first arm 73 can be increased.

[0046] The rotational speed ratio of the output shaft 238 to the input shaft 237, that is, the reduction ratio V1 of the first reducer 23A, is not particularly limited, but a preferable range thereof will be described later.

[0047] Although not shown, the input shaft of the second reducer 23B is connected to a motor 31 fixed to the base end 74A of the second arm 74, and as shown in Figure 4, the output shaft of the second reducer 23B is fixed to the bottom of a recess 733 formed in the tip end 73B of the first arm 73.

[0048] Alternatively, the input shaft of the second reducer 23B may be connected to a motor 31 fixed to the tip end 73B of the first arm 73, and the output shaft of the second reducer 23B may be fixed to the base end 74A of the second arm 74.

[0049] Then, second arm 74 can rotate relative to first arm 73 based on the same principle as above.

[0050] The internal gear 233 has higher elasticity than the sun gear 234 and the planetary gears 235. This reduces backlash, and further improves the positional accuracy of each part when the robot arm 72 is in operation.

[0051] "Elasticity" in this specification is determined not only by the material but also by the shape, etc., and refers to the property of an object that, when a force is applied to it, returns to its original shape when the force is released. High elasticity means that an object quickly returns to its original shape when the force is released. In other words, "elasticity" in this specification is different from properties determined by the material, such as Young's modulus.

[0052] The casing 231, the internal gear 233, the sun gear 234, the planetary gears 235, the carrier 236, the input shaft 237, and the output shaft 238 are made of, for example, a metal material or a hard resin material.

[0053] As described above, the first reducer 23A includes a ring-shaped internal gear 233, a sun gear 234 that is arranged inside the internal gear 233 and concentrically with the internal gear 233, a plurality of planetary gears 235 that mesh with both the internal gear 233 and the sun gear 234, and a carrier 236 that rotatably supports each planetary gear 235, and the internal gear 233 has higher elasticity than the planetary gears 235. This makes it possible to suppress backlash and further improve the positional accuracy of each part of the robot arm 72.

[0054] The internal gear 233 is not limited to the above configuration, and may have elasticity equivalent to that of the planetary gear 235, or may have elasticity lower than that of the planetary gear 235.

[0055] Furthermore, the first reducer 23A has a single gear train including the sun gear 234 and the plurality of planetary gears 235. By minimizing the number of gear trains in this way, it is possible to reduce loss during torque transmission in the first reducer 23A. Furthermore, it is possible to reduce the weight of the first reducer 23A.

[0056] Furthermore, it is preferable that the internal gear 233, sun gear 234, and planetary gears 235 are each helical gears. That is, it is preferable that the internal gear 233, sun gear 234, and planetary gears 235 are helical gears. This allows the meshing area of ​​the teeth to be larger than in spur gears, and reduces the surface pressure on the tooth surfaces, making it possible to transmit relatively high torque smoothly and efficiently.

[0057] The internal gear 233, the sun gear 234, and the planetary gears 235 are not limited to the above configuration, and may be other types of gears, such as spur gears.

[0058] The reduction ratio V1 of the first reducer 23A is preferably 1 / 100 or more and 1 / 3 or less, and more preferably 1 / 50 or more and 1 / 3 or less.

[0059] The reduction ratio V2 of the second reducer 23B is preferably 1 / 100 or more and 1 / 3 or less, and more preferably 1 / 50 or more and 1 / 3 or less.

[0060] The magnitude relationship between the reduction ratios V1 and V2 is not particularly limited, but it is preferable that V1≧V2, and more preferably that 0.85V1≧V2.

[0061] Such reduction ratios V1 and V2 can be set by appropriately selecting the numbers of the internal teeth 233A, the teeth 234A, and the teeth 235A.

[0062] Compared to strain wave gear type reducers with the same maximum outer diameter, such planetary gear type reducers (first reducer 23A, second reducer 23B) have lower grease viscosity resistance and less torque loss. Therefore, when operating at the same rotational speed, using a planetary gear type reducer enables agile operation while reducing power consumption.

[0063] Next, the shape of the first arm 73 will be described. 4, the first arm 73 has a base end 73A, a tip end 73B, and an intermediate portion 73C therebetween. The base end 73A and the tip end 73B each extend horizontally. That is, the thickness of the base end 73A and the tip end 73B is approximately equal to the thickness of the vertical end.

[0064] The intermediate portion 73C has an inclined portion 730 that is inclined from the base end portion 73A toward the tip end portion 73B so as to approach the robot installation surface 100. Therefore, the tip end portion 73B is located closer to the robot installation surface 100 than the base end portion 73A.

[0065] In the illustrated configuration, the entire intermediate portion 73C is the inclined portion 730. However, the present invention is not limited to this configuration, and the inclined portion 730 may be formed only in a part of the intermediate portion 73C.

[0066] The inclined portion 730 provides the robot 7 with the following effects and advantages. Compared to a case where the inclined portion 730 is not provided and the first arm 73 is parallel to the robot installation surface 100 along its entire length (hereinafter simply referred to as "the entire first arm 73 being horizontal"), the tip end 73B of the first arm 73 is located closer to the robot installation surface 100. Therefore, compared to a case where the entire first arm 73 is horizontal, the second arm 74 connected to the tip end 73B and the work head 75 connected to (mounted on) the second arm 74 are located closer to the robot installation surface 100. This reduces the length of the robot 7 along the first rotation axis J1, i.e., the maximum height of the robot 7. This allows the robot 7 to be made smaller, and in particular, the maximum height of the robot 7 to be reduced (hereinafter referred to as "low profile"). As a result, there is an effect of increasing the degree of freedom in selecting the installation location of the robot 7 and increasing the degree of freedom in the type, content, and conditions of work.

[0067] In particular, planetary gear reducers such as the first reducer 23A and the second reducer 23B have long axial lengths of the first rotation shaft J1 and the second rotation shaft J2, which increases the maximum height of the robot 7 and tends to lead to an increase in size. For this reason, in the robot 7 equipped with a planetary gear reducer in particular, the inclined portion 730 of the first arm 73 makes the above-mentioned effect more pronounced.

[0068] Furthermore, with the configuration including the inclined portion 730, the axial position (vertical position) of the first rotation axis J1 of the first arm 73 changes gradually and continuously from the base end 73A side toward the tip end 73B side. This makes it possible to prevent or mitigate stress concentration at a specific portion of the first arm 73. Therefore, it is possible to ensure sufficient strength of the first arm 73.

[0069] The inclined portion 730 has a first inclined surface 731 which is the upper surface of the first arm 73, and a second inclined surface 732 which is the lower surface of the first arm 73. The first inclined surface 731 and the second inclined surface 732 are inclined so as to approach the robot installation surface 100 from the base end portion 73A side toward the tip end portion 73B side.

[0070] In this embodiment, the first inclined surface 731 and the second inclined surface 732 are parallel. That is, the angle θ1 of the first inclined surface 731 relative to the robot installation surface 100 and the angle θ2 of the second inclined surface 732 relative to the robot installation surface 100 are equal, and the distance between the first inclined surface 731 and the second inclined surface 732 is constant. This allows the thickness of the inclined portion 730 to be constant along its longitudinal direction, allowing the first arm 73 to exhibit sufficient strength. However, in the present invention, the magnitude relationship between the angles θ1 and θ2 is not limited to being equal. Note that the first inclined surface 731 and the second inclined surface 732 do not need to be strictly flat, and may include surfaces that have partial curves or that function substantially the same as flat surfaces as structural members of the first arm 73.

[0071] The angles θ1 and θ2 may be equal, as in the illustrated configuration, or may be different. The angle θ1 is preferably, for example, 2° to 60°, and more preferably, 5° to 45°. The angle θ2 is preferably, for example, 2° to 60°, and more preferably, 5° to 45°. This allows the robot 7 to be miniaturized and increases the degree of freedom in terms of the type of work, the work content, and the work conditions. If the angles θ1 and θ2 are too small, the robot 7 may not be miniaturized, particularly in terms of its low profile. If the angles θ1 and θ2 are too large, unless the length of the first arm 73 is shortened, the second arm 74 and the work head 75 connected to (mounted on) the second arm 74 may be too close to the robot installation surface 100, which may actually limit the degree of freedom in work. If the length of the first arm 73 is shortened to avoid this, the work area becomes smaller, which also limits the degree of freedom in work.

[0072] Furthermore, since the first arm 73 has an inclined portion 730, when the robot 7 is viewed from the front (the right side in Figures 1 and 4), that is, when viewed in a direction from the base end 73A toward the tip end 73B on a plane parallel to the robot installation surface 100, the first reducer 23A and the second reducer 23B are all or partially overlapped in a direction along the first rotation axis J1 (axial direction). In other words, the upper end of first reducer 23A is positioned vertically higher than the lower end of second reducer 23B. Here, the upper end of first reducer 23A refers to the upper surface 232A of casing 231 excluding output shaft 238, and the lower end of second reducer 23B refers to the lower surface 232B of casing 231 excluding output shaft 238. With this configuration, it is possible to more reliably reduce the size of robot 7, particularly its height.

[0073] Let L0 be the length of the overlapping region of the first reducer 23A and the second reducer 23B in the direction along the first rotation axis J1 (vertical direction in this embodiment), and L1 be the length of the first reducer 23A in the direction along the first rotation axis J1 (vertical direction). L0 / L1 is preferably 0.1 or greater and 1.0 or less, and more preferably 0.2 or greater and 0.8 or less. This ensures the effect of the overlapping of the first reducer 23A and the second reducer 23B, i.e., the miniaturization of the robot 7, particularly the reduction in height. If L0 / L1 is too small, the effect of the overlapping of the first reducer 23A and the second reducer 23B is diminished. Furthermore, when L0 / L1=1, the improvement in effect is smaller than when L0 / L1 is greater than 0.8 and less than 1.0.

[0074] Furthermore, when the distance between the center of gravity G1 of the first reducer 23A and the center of gravity G2 of the second reducer 23B in the direction along the first rotation axis J1 (the vertical direction in this embodiment) is defined as D1, and the distance between the first rotation axis J1 and the second rotation axis J2 is defined as D2, D1 / D2 is preferably 0.01 or more and 0.8 or less, and more preferably 0.1 or more and 0.7 or less. This makes it possible to more reliably achieve the effect of overlapping the first reducer 23A and the second reducer 23B, i.e., the miniaturization of the robot 7, particularly the reduction in height. If D1 / D2 is too small, the effect of overlapping the first reducer 23A and the second reducer 23B is diminished, and if D1 / D2 is too large, further improvement in the effect tends to be limited.

[0075] Furthermore, D1 / L1 is preferably 0.01 or more and 0.9 or less, and more preferably 0.1 or more and 0.7 or less, which makes it possible to more reliably achieve the effect of overlapping the first reducer 23A and the second reducer 23B, i.e., to make the robot 7 smaller, particularly to make it thinner.

[0076] As described above, the robot 7 includes the base 71 installed on the robot installation surface 100, the first arm 73 having a base end 73A and a tip end 73B, the base end 73A of which is connected to the base 71 via the first joint 2K so as to be rotatable around the first rotation axis J1, the second arm 74 connected to the tip end 73B of the first arm 73 via the second joint 3K so as to be rotatable around the second rotation axis J2 parallel to the first rotation axis J1, and the second arm 74 connected to the tip end 73B of the first arm 73 via the second joint 3K so as to be rotatable around the third rotation axis J3 parallel to the first rotation axis J1. and a work head 75 that is a shaft connected to the second arm 74 so as to be movable along the axis of rotation. The first joint 2K has a first reducer 23A, and the second joint 3K has a second reducer 23B. At least one of the first reducer 23A and the second reducer 23B (in this embodiment, both) is a planetary gear reducer. The first arm 73 has an inclined portion 730 that is inclined so that the tip end 73B is closer to the robot installation surface 100 than the base end 73A. This allows the length of the robot 7 along the first rotation axis J1 (maximum height of the robot 7) to be reduced, thereby enabling the robot 7 to be made smaller, particularly low-profile. As a result, there is greater freedom in selecting the installation location of the robot 7, as well as greater freedom in the type, content, and conditions of work.

[0077] In this embodiment, the case where both the first reducer 23A and the second reducer 23B are planetary gear type reducers has been described, but the present invention is not limited to this, and the first reducer 23A may be a planetary gear type reducer and the second reducer 23B may be a reducer of another type, or the second reducer 23B may be a planetary gear type reducer and the first reducer 23A may be a reducer of another type.

[0078] The inclined portion 730 has a first inclined surface 731 located on the side of the first arm 73 opposite the robot installation surface 100, and a second inclined surface 732 located on the side of the first arm 73 facing the robot installation surface 100, and the distance between the first inclined surface 731 and the second inclined surface 732 is constant. This eliminates the need for a portion where the thickness changes abruptly along the longitudinal direction of the first arm 73 when viewed as a whole. Therefore, the first arm 73 does not need to have a portion where stress concentration is likely to occur, such as a portion where the thickness changes abruptly, and the first arm 73 can be ensured to have sufficient strength.

[0079] Note that either the first inclined surface 731 or the second inclined surface 732 may be omitted, and instead configured with a surface extending in the horizontal direction.

[0080] When viewed in a direction from the base end 73A toward the tip end 73B on a plane parallel to the robot installation surface 100, the first reducer 23A and the second reducer 23B have an overlapping portion. This makes it possible to more reliably reduce the size of the robot 7, particularly its height.

[0081] When viewed in a direction from the base end 73A side toward the tip end 73B side on a plane parallel to the robot installation surface 100, the first reducer 23A and the second reducer 23B do not have to overlap.

[0082] Second Embodiment FIG. 5 is a perspective view showing the internal structure of a first reducer included in a robot according to a second embodiment of the present invention.

[0083] A robot according to a second embodiment of the present invention will be described below with reference to Fig. 5. The following description will focus on differences from the first embodiment, and a description of similarities will be omitted. Note that in Fig. 5, the vertical length is exaggerated to make the internal structure easier to understand.

[0084] The first reducer 23A has two gear trains each including a sun gear 234 and a plurality of planetary gears 235. That is, as shown in Fig. 5, a gear train 230A including a sun gear 234 and three planetary gears 235 is provided on a predetermined cross section of the first reducer 23A, and a gear train 230B including a sun gear 234 and three planetary gears 235 is provided on another cross section shifted a predetermined distance in the axial direction of the axis O1.

[0085] The gear trains 230A and 230B are arranged side by side along the axial direction of the axis O1. The lower side in Fig. 5 is the input side (the input shaft 237 side), and the upper side in Fig. 5 is the output side (the output shaft 238 side). The gear train 230A is arranged on the input side, and the gear train 230B is arranged on the output side.

[0086] Gear train 230A and gear train 230B share one internal gear 233. Furthermore, carrier 236 of gear train 230A is connected to sun gear 234 of gear train 230B via a shaft-shaped connecting portion 239. That is, connecting portion 239 serves as both the output shaft of gear train 230A and the input shaft of gear train 230B. For this reason, the gear train 230A reduces the speed, and the gear train 230B also reduces the speed. As a result, in this embodiment, the reduction ratio V1 of first reducer 23A can be increased, for example, to between 1.3 and 3.5 times that of the first embodiment.

[0087] Thus, in the first reducer 23A, the gear train of the sun gear 234 and the plurality of planetary gears 235 is provided in multiple rows (two rows in this embodiment) along the direction of the axis O1, which is the central axis of the internal gear 233. This makes it possible to increase the reduction ratio V1 of the first reducer 23A with a simple structure, and to stably output a relatively high torque.

[0088] In particular, in a configuration having two gear trains, 230A and 230B, as in this embodiment, the length of the first rotation axis J1 in the axial direction is longer than in the first embodiment, which tends to lead to an increase in the size of the robot. For this reason, by providing the inclined portion 730 in this embodiment, the above-mentioned effect can be obtained more significantly.

[0089] Gear train 230A and gear train 230B may be the same or different in various conditions such as the diameter of sun gear 234 and planetary gear 235, tooth thickness, number of planetary gears 235, number of teeth 234A and teeth 235A, etc. In particular, gear train 230A and gear train 230B may be the same or different in reduction ratio.

[0090] In this embodiment, the case where two gear trains are provided along the axial direction of the axis O1 has been described, but the present invention is not limited to this, and three or more gear trains may be provided.

[0091] Third Embodiment FIG. 6 is a side view of a first arm included in a robot according to a third embodiment of the present invention.

[0092] Hereinafter, the third embodiment of the robot of the present invention will be described with reference to FIG. 5. The following description will focus on the differences from the first and second embodiments, and will omit a description of similar points.

[0093] 6, the intermediate portion 73C of the first arm 73 has a step portion 734. The step portion 734 is a portion where the height in the axial direction (vertical direction) of the first rotation axis J1 changes abruptly, and in this embodiment, the first arm 73 is bent in a crank shape. A portion of the intermediate portion 73C on the base end side from the step portion 734 is at the same height as the base end portion 73A. A portion of the intermediate portion 73C on the tip end side from the step portion 734 is at the same height as the tip end portion 73B.

[0094] By providing such a step portion 734, the tip end 73B is positioned closer to the robot installation surface 100 than the base end 73A. The length of the robot 7 along the first rotation axis J1 can be shortened, and the robot 7 can be made smaller, particularly with a lower profile. As a result, there is greater freedom in selecting the installation location of the robot 7, as well as greater freedom in the type of work, work content, work conditions, and other aspects of the work.

[0095] In particular, in the configuration having the step portion 734, the length of the first arm 73 can be appropriately shortened, and therefore the robot 7 can be made even more compact.

[0096] As described above, the robot 7 includes the base 71 installed on the robot installation surface 100, the first arm 73 having a base end 73A and a tip end 73B, the base end 73A of which is connected to the base 71 via the first joint 2K so as to be rotatable about a first rotation axis J1, the second arm 74 connected to the tip end 73B of the first arm 73 via the second joint 3K so as to be rotatable about a second rotation axis J2 parallel to the first rotation axis J1, and the second arm 74 movable along a third rotation axis J3 parallel to the first rotation axis J1. 4, and a work head 75 which is a shaft connected to the first joint 2K. The first joint 2K has a first reducer 23A, and the second joint 3K has a second reducer 23B. At least one of the first reducer 23A and the second reducer 23B (in this embodiment, both) is a planetary gear reducer. The first arm 73 has a step portion 734 between the base end 73A and the tip end 73B, whose height in the direction of the first rotation axis J1 varies, and the tip end 73B is closer to the robot installation surface 100 than the base end 73A. This allows the length of the robot 7 along the first rotation axis J1 (maximum height of the robot 7) to be reduced, thereby enabling the robot 7 to be made smaller, particularly low-profile. As a result, there is greater freedom in selecting an installation location for the robot 7, as well as greater freedom in the type, content, and conditions of work.

[0097] The step portions 734 may be provided at a plurality of locations on the first arm 73. For example, the step portions 734 may be provided at two or three or more locations along the longitudinal direction of the first arm 73.

[0098] The numerical ranges (L0 / L1, D1 / D2, D1 / L1) described in the first embodiment can also be applied to the third embodiment, thereby achieving the same effects as those described above.

[0099] The first embodiment may be combined with the third embodiment, that is, the first arm 73 may have both the inclined portion 730 and the stepped portion 734.

[0100] In this embodiment, at least one of the first reducer 23A and the second reducer 23B may have the configuration of the second embodiment.

[0101] While the robot of the present invention has been described above based on the illustrated embodiments, the present invention is not limited to these, and the configuration of each part can be replaced with any configuration having a similar function. In addition, any other components may be added. [Explanation of symbols]

[0102] REFERENCE SIGNS LIST 1...robot system, 2...motor unit, 2K...first joint section, 3...motor unit, 3K...second joint section, 4...first drive mechanism, 4K...third joint section, 5...second drive mechanism, 5K...fourth joint section, 6...control device, 7...robot, 21...motor, 22...power transmission mechanism, 23A...first reducer, 23B...second reducer, 31...motor, 32...power transmission mechanism, 41...motor, 42...power transmission mechanism, 51...motor, 52...power transmission mechanism, 71...base, 72...robot arm, 73...first arm, 73A...base end section, 73B...tip end section, 73C...intermediate section, 74...second arm, 74A...base end section, 74B...tip end section, 75...work head, 76...end effector , 83A...base end, 100...robot installation surface, 230A...gear train, 230B...gear train, 231...casing, 232A...upper surface, 232B...lower surface, 233...internal gear, 233A...internal teeth, 234...sun gear, 234A...teeth, 235...planetary gear, 235A...teeth, 236...carrier, 237...input shaft, 238...output shaft, 239...connecting portion, 730...inclined portion, 731...first inclined surface, 732...second inclined surface, 733...recess, 734...step portion, 751...spline nut, 752...ball screw nut, 753...spline shaft, G1...center of gravity, G2...center of gravity, J1...first rotation axis, J2...second rotation axis, J3...third rotation axis, O1...axis, O2...axis, θ1...angle, θ2...angle

Claims

1. a base to be installed on the robot installation surface; a first arm having a base end and a tip end, the base end being connected to the base via a first joint portion so as to be rotatable around a first rotation axis; a second arm connected to the tip end of the first arm via a second joint portion so as to be rotatable about a second rotation axis parallel to the first rotation axis; a shaft connected to the second arm so as to be movable along a third rotation axis parallel to the first rotation axis; the first joint portion has a first reducer, the second joint portion has a second reducer, and at least one of the first reducer and the second reducer is a planetary gear type reducer, The robot is characterized in that the first arm has an inclined portion inclined so that the tip end is closer to the robot installation surface than the base end.

2. The inclined portion is a first inclined surface located on the first arm opposite to the robot installation surface; a second inclined surface located on the robot installation surface side of the first arm, The robot according to claim 1 , wherein the distance between the first inclined surface and the second inclined surface is constant.

3. an angle θ1 of the first inclined surface with respect to the robot installation surface is equal to or greater than 2° and equal to or less than 60°; The robot according to claim 2 , wherein an angle θ2 of the second inclined surface with respect to the robot installation surface is equal to or greater than 2° and equal to or less than 60°.

4. 4. The robot according to claim 1, wherein the first reducer and the second reducer have an overlapping portion when viewed in a direction from the base end side toward the tip end side on a plane parallel to the robot installation surface.

5. 5. The robot according to claim 4, wherein when L0 is the length of the area where the first reducer and the second reducer overlap in the direction along the first rotation axis and L1 is the length of the first reducer in the direction along the first rotation axis, L0 / L1 is greater than or equal to 0.1 and less than or equal to 1.

0.

6. 5. The robot according to claim 4, wherein when a distance D1 is a distance between a center of gravity G1 of the first reducer and a center of gravity G2 of the second reducer in a direction along the first rotation axis, and a distance D2 is a distance between the first rotation axis and the second rotation axis, D1 / D2 is greater than or equal to 0.01 and less than or equal to 0.

8.

7. a base to be installed on the robot installation surface; a first arm having a base end and a tip end, the base end being connected to the base via a first joint portion so as to be rotatable around a first rotation axis; a second arm connected to the tip end of the first arm via a second joint portion so as to be rotatable about a second rotation axis parallel to the first rotation axis; a shaft connected to the second arm so as to be movable along a third rotation axis parallel to the first rotation axis; the first joint portion has a first reducer, the second joint portion has a second reducer, and at least one of the first reducer and the second reducer is a planetary gear type reducer, the first arm has a step portion between the base end and the tip end, the height of which changes in the direction of the first rotation axis, and the tip end is closer to the robot installation surface than the base end.

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