JPH11170184A - Robot arm structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an arm structure in a robot having an arm axis at an end portion of an arm, which is capable of improving the position accuracy even when operated at high speed by reliably suppressing the vibration of the arm axis. . A central portion of an upper support plate is fixed to a lower side of a second horizontal arm, and both ends of the upper support plate protrude outside the second horizontal arm. At both ends of the upper support plate 21, the main arm shaft 1
Auxiliary arm shafts 23 are inserted in parallel with 5, and the auxiliary arm shaft 23 is supported by a bearing 22 attached to an upper support plate 21 so as to be able to move up and down. The lower end of the auxiliary arm shaft 23 is fixed to the lower support plate 24. The lower support plate 24 is provided with a bearing 25 that rotatably supports the main arm shaft 15 through the main arm shaft 15 and supports the lower end of the main arm shaft 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a robot arm structure and, more particularly, to a technique suitable for a tip structure of a robot arm of a horizontal articulated robot.

[0002]

2. Description of the Related Art There are various types of conventional industrial robots, and among them, a horizontal articulated robot is one which is particularly excellent in flexibility in work contents. In this horizontal articulated robot, a vertical arm shaft that can move up and down and can rotate around an axis is attached to the tip of the horizontal arm. There is provided a mounting end for mounting an end effector such as a robot hand for gripping and moving.

A spiral groove formed spirally and a spline groove extending in the axial direction are formed on the outer peripheral surface of the vertical arm shaft. The vertical arm shaft is inserted into the ball screw nut and the ball spline nut stored at the tip of the horizontal arm, and the spiral groove meshes with the ball screw nut,
The spline groove meshes with the ball spline nut. The ball screw nut and the ball spline nut are rotatably supported at the distal ends of the horizontal arms, respectively. The spline nut is configured to be driven by a rotation drive motor for rotating the vertical arm shaft around the axis via a drive belt or the like.

[0004]

In the above-mentioned conventional horizontal articulated robot, an end effector is mounted on the lower end of a vertical arm shaft attached to the distal end of the horizontal arm. Work to grasp and move parts and the like. In this case, if the weight of the part is large or the turning acceleration of the tip of the horizontal arm during the work is large, the stress applied to the vertical arm axis in the direction intersecting the axial direction becomes excessive, and the vertical arm axis is bent and the end The effector may vibrate, making it difficult to position the component, resulting in poor positional accuracy. In particular, when the movement stroke of the vertical arm shaft in the axial direction is lengthened, there is a problem that the above-mentioned vibration is further increased when the vertical arm shaft is extended downward.

For this purpose, conventionally, a method has been adopted in which the diameter of the vertical arm shaft is increased, or the supporting area of the mounting portion of the vertical arm shaft with respect to the tip of the horizontal arm is lengthened vertically. Neither is enough to prevent the vibration of the lower end of the vertical arm shaft, and if the rigidity of the vertical arm shaft is increased by the method described above, the size and weight of the arm tip will further increase, The operating performance is reduced and the compactness is lacking. Further, it is necessary to increase the rigidity of the arms and joints of the entire robot, resulting in a significant cost increase.

[0006] Such a problem is not limited to the above-mentioned horizontal articulated robot, but also occurs when an arm shaft is attached to the tip of an arm of a linear motion robot.

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problem, and an object of the present invention is to provide an arm structure of a robot having an arm shaft having a mounting end for mounting an end effector at the distal end thereof. It is an object of the present invention to provide an arm structure capable of improving position accuracy even when operated at high speed by reliably suppressing vibration of an arm shaft.

[0008]

Means taken by the present invention to solve the above-mentioned problems are that a robot arm and a robot arm are attached to the robot arm so as to be movable at least in the axial direction, and a robot working element is provided. In a robot arm structure including a main arm axis having a mounting end, an auxiliary arm axis extending parallel to the main arm axis is provided, and the main arm axis and the auxiliary arm axis are separated at least in the axial direction. Directly or indirectly supporting each other so as to keep at least a mutual interval at two places.

According to this means, the auxiliary arm shaft is provided which extends parallel to the main arm shaft attached to the robot arm and is mutually supported at least at two positions separated in the axial direction. Can be increased by supporting the auxiliary arm shaft, and the vibration of the robot working element mounted on the mounting end at the tip of the main arm shaft can be suppressed and reduced.

In this case, the main arm shaft may not only move in the axial direction with respect to the robot arm but also be rotatable about the axis.

In this case, a distal end side support portion for mutually supporting the auxiliary arm shaft is provided near the mounting end of the main arm shaft, and the auxiliary support portion is provided near a mounting portion of the main arm shaft to the robot arm. It is preferable to provide a mounting-side support portion that mutually supports the arm shaft.

According to this means, by providing the distal end supporting portion supported by the auxiliary arm shaft near the mounting end of the main arm shaft, the main arm shaft can be surely moved by the auxiliary arm shaft near the mounting end. The auxiliary arm shaft can be fixed by a highly rigid robot arm by providing a mounting side support portion near the mounting portion for the robot arm, so that the rigidity of the main arm shaft can be efficiently reduced. Since the vibration can be increased, the vibration of the robot working element can be further reduced.

[0013] Further, the auxiliary arm shaft is attached to the robot arm so as to be movable in the axial direction so that a mounting side support portion is a mounting portion of the main arm shaft to the robot arm. It is preferable that the auxiliary arm shafts are indirectly supported by each other via the robot arm.

According to this means, since the auxiliary arm axis is attached to the robot arm, the mounting side between the main arm axis and the auxiliary arm axis is mutually supported via the robot arm. The support strength of the main arm shaft by the arm shaft can be further increased.

At this time, if the main arm shaft is configured to be rotatable around its axis, the main arm shaft is directly or indirectly attached to the auxiliary arm shaft near the mounting end. What is necessary is just to mutually support rotatably.

Further, in each of the above-mentioned means, it is preferable that the auxiliary arm shaft is disposed closer to a base end of the robot arm with respect to the main arm shaft.

According to this means, since the auxiliary arm shaft is disposed near the base end of the robot arm, an increase in the moment of inertia of the robot arm due to the attachment of the auxiliary arm shaft can be suppressed, and the auxiliary arm shaft can be mounted. It is possible to prevent the interference with other members from being deteriorated due to the attachment, thereby achieving a compact configuration. In particular, when the robot arm turns as in the case of an articulated robot, it is possible to suppress a decrease in operation performance due to an increase in the moment of inertia.

It is preferable that a plurality of the auxiliary arm axes are arranged in the moving direction of the robot arm with respect to the main arm axis.

According to this means, by arranging a plurality of auxiliary arm axes in the moving direction of the robot arm, the supporting strength of the main arm axis in the moving direction can be increased, so that the main arm axis can be effectively moved. Vibration can be suppressed and position accuracy can be improved. In this case,
It is desirable that the plurality of auxiliary arms be symmetrically arranged with respect to the main arm. By symmetrically arranging the plurality of auxiliary arms, it is possible to reduce a difference in operation characteristics caused by a difference in the moving direction of the robot arm.

Further, it is preferable that the auxiliary arm shaft has a hollow structure, and wiring or piping for the robot working element is inserted into the auxiliary arm shaft.

According to this means, by inserting the inside of the auxiliary arm shaft, the positions of the wiring and the piping can be held, it is difficult to interfere with other members, and when the inside of the main arm shaft is inserted. The connection to the robot working element can be made more easily than in the case of the first embodiment.

Further, it is preferable that the main arm shaft and the auxiliary arm shaft are mutually supported near a mounting end via a support member connected to the main arm shaft and the auxiliary arm shaft.

According to this means, the main arm shaft and the auxiliary arm shaft are mutually supported via the support member near the mounting end, thereby suppressing an increase in the weight mounted on the distal end of the robot arm. Moreover, the vibration of the robot working element can be reliably reduced.

In this case, it is preferable that a driving element for the robot working element is fixed to the supporting member.

According to this means, the distance between the robot working element and the driving element can be shortened by fixing the driving element to the support member, so that the control delay can be reduced and the speed can be reduced quickly. A robot working element can be driven. The driving element is, for example, a valve mechanism such as an electromagnetic valve when using an air actuator as a robot working element, and a mechanical driving source such as an electric motor when using a mechanical actuator as a robot working element. is there.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a robot arm structure according to the present invention will be described with reference to the accompanying drawings. FIG. 1 is a cutaway perspective view showing the overall schematic configuration of the present embodiment. The present embodiment relates to a horizontal articulated robot, but the present invention is not limited to a horizontal articulated robot.
As long as the robot arm has a drive arm shaft that moves in the axial direction at the end of the robot arm, the present invention can be applied to other types of robots such as a linear motion robot.

In the present embodiment, the first shaft portion 10
The horizontal arm 11 is pivotally attached, and the second horizontal arm 12 is pivotally attached to the first horizontal arm 11. A ball screw nut 13 and a ball spline nut 14 are rotatably supported at the distal end of the second horizontal arm 12 via bearings. The ball screw nut 13 and the ball spline nut 14 are connected to the main arm shaft 15 by a main arm shaft 15. It is inserted.

Although not shown, the main arm shaft 15 is formed with a spiral groove extending spirally on the outer peripheral surface and a plurality of spline grooves extending axially (vertically) on the outer peripheral surface. . The helical groove receives the ball projecting from the inner peripheral surface of the ball screw nut 13 of the ball row circulated and accommodated therein, and engages the ball screw nut 13 and the main arm shaft 15 in a screwing manner. On the other hand, the spline groove receives the ball protruding from the inner peripheral surface of the ball spline nut 14 in the ball row circulated and accommodated therein, and engages the ball spline nut 14 and the main arm shaft 15 in the rotation direction. . The ball screw nut 13 is a driving belt 13a.
The ball spline nut 14 is rotatably driven by a rotary drive motor 17 via a drive belt 14a.

A resin tube 10a extends from the base shaft portion 10 and is connected to the base end of the second horizontal arm 12. Inside the resin tube 10a, there are wires and wires drawn from a control unit inside the base shaft portion 10. An air pipe or the like connected to the air compressor is inserted. The wiring is connected to an air supply mechanism (not shown) that includes drive motors and solenoid valves housed in the second horizontal arm 12. An air pipe is introduced into the air supply mechanism. Another air pipe (not shown) derived from the air introduction mechanism is drawn out from the outlet 19 and connected to a robot hand mounted on a mounting end 15 a provided at a lower end of the main arm shaft 15. Is used to air-drive the robot hand.

A central portion of an upper support plate 21 is fixed to a lower portion of the second horizontal arm 12 and near a base end of the second horizontal arm 12 adjacent to the mounting position of the main arm shaft 15. Both ends of the upper support plate 21 protrude outside the casing of the second horizontal arm 12, respectively. Auxiliary arm shafts 23, 23 are respectively inserted through both ends of the upper support plate 21, and these auxiliary arm shafts 23, 23 are supported by bearings 22 attached to the upper support plate 21 so as to be able to move up and down.

The lower end portions of the pair of auxiliary arm shafts 23 are fixed to the distal ends of the lower support plate 24 in the shape of a square. The lower support plate 24 also has a bearing 25 (contained inside) that rotatably supports the main arm shaft 15 through the main arm shaft 15. The bearing 25 supports the main arm shaft 15 in the vicinity of a mounting end 15 a formed at the lower end of the main arm shaft 15. The mounting end 15a is configured to removably mount a robot hand (not shown).

The main arm shaft 15 is provided with the elevation drive motor 1
6 rotates the ball screw nut 13 up and down with respect to the second horizontal arm 12, and rotates the ball spline nut 14 by the rotation drive motor 17 to rotate around the axis. It has become. As shown in FIG. 2 which is a side view of the present embodiment, when the main arm shaft 15 moves up and down, the lower support plate 24 on which the bearing 25 that supports the lower end of the main arm shaft 15 is also moved up and down. As a result, the auxiliary arm shaft 23 also moves up and down.

FIG. 3 is a plan view of this embodiment viewed from above. As shown in this figure, the first horizontal arm 11 is configured to pivot in both the left and right directions with respect to the base shaft portion 10, and the second horizontal arm 12 is also rotated left and right with respect to the first horizontal arm 11. It turns in any direction. The main arm shaft 15 and the pair of auxiliary arm shafts 23 also rotate together with the rotation of the second horizontal arm 12, and these main arm shafts 15 and auxiliary arm shafts 23 can move up and down integrally as shown in FIG. . Furthermore, the main arm shaft 15
Can rotate around its axis.

FIG. 4 is a plan view showing a structure for mutually supporting the main arm shaft 15 and a pair of auxiliary arm shafts 23, 23. The main arm shaft 15 and the auxiliary arm shafts 23, 23 are mutually supported by a lower support plate 24 near the lower end so as to maintain an interval therebetween. On the other hand, the main arm shaft 15 is supported by the ball screw nut 13 and the ball spline nut 14 with respect to the second horizontal arm 12, and the auxiliary arm shaft 23 is connected to the second horizontal arm 1.
Bearings 22 mounted on the upper support plate 21 for
Is supported by

Therefore, the main arm shaft 15 and the auxiliary arm shaft 23 are mutually indirectly supported at two locations separated from each other in the axial direction so as to maintain a mutual interval. Therefore, the vibration of the main arm shaft 15 caused by the turning motion of the second horizontal arm 12 (this turning motion is also generated by the turning motion of the first horizontal arm 11) can be suppressed and reduced.

In this case, in particular, the main arm shaft 15 and the auxiliary arm shaft 23 are located at a portion near the lower end of the main arm shaft 15, that is, at a portion near an attachment portion of an end effector (robot working element) such as a robot hand. Since they are mutually supported by the lower support plate 24, vibration can be effectively suppressed even when the main arm shaft 15 is extended downward.

The auxiliary arm shaft 23 is disposed closer to the base end of the second horizontal arm 12 with respect to the main arm shaft 15, that is, closer to the turning center of the turning motion of the second horizontal arm 12. (2) An increase in the moment of inertia of the horizontal arm 12 can be suppressed, the motion performance of the robot can be maintained, and insufficient rigidity at the base end side can be avoided. In addition, since the outer trajectory of the robot viewed from the base end of the second horizontal arm can be made compact without extending outward, interference with other obstacles does not deteriorate.

Further, the two auxiliary arm shafts 23
Since the horizontal arms 12 are arranged in the moving direction, that is, in the turning direction of the turning motion, the rigidity with respect to the acceleration of the turning motion can be increased, so that the vibration of the main arm shaft 15 is particularly effective. Moreover, a pair of auxiliary arm shafts 2
3 is arranged symmetrically in the turning direction with respect to the main arm shaft 15, so that the positioning accuracy of the robot working element can be improved without causing asymmetry of the operation characteristics.

In the above embodiment, the main arm shaft 15
When the main arm shaft 15 is hollow, wires, air pipes, and the like drawn out from the outlet 19 are inserted from the upper end of the main arm shaft 15 and drawn out from the lower end of the main arm shaft 15 through the inside. Is connected to a robot hand (not shown) mounted on the mounting end 15a. However, in this case, the wiring and piping connected to the robot hand must be the main arm shaft 1 except when the robot hand has a special structure.
5 needs to be taken out once from the lower end, and then connected, so that the lower end structure of the main arm shaft 15 needs to be somewhat devised.

When the main arm shaft 15 is not hollow, the main arm shaft 15 is fixed on the outer surface of the casing of the second horizontal arm 12 from the outlet 19, and is further extended downward to be connected to the robot hand. However, in this case, there is a possibility that the wiring or the pipe moves due to a turning operation or the like or interferes with another obstacle. At this time, wiring and air piping may be spirally arranged around the main arm shaft 15,
In particular, in the case of the present embodiment, the positions of the wiring and the piping may be stabilized by spirally wrapping around the auxiliary arm shaft 23.

Here, as shown in FIG. 5, in the above embodiment, the auxiliary arm shaft 23 is made hollow, and air pipes 31 and 32 are inserted from the upper end of the auxiliary arm shaft 23 into the inside. Air pipes 31 and 32 may be pulled out from the lower end of the main arm shaft 15 and connected to the robot hand 30 configured as an air actuator attached to the lower end of the main arm shaft 15. In this case, unlike the conventional case where the wiring and the air pipe are inserted through the main arm shaft 15, the wiring and the connection of the pipe to the robot hand 30 do not become difficult. And can be easily and smoothly connected.

As shown in FIG. 6, a solenoid valve 36 and the like may be attached to the lower support plate 24. Here, the solenoid valve 36 constitutes a driving element of the robot hand 30, and may be an electric motor, a hydraulic cylinder, or the like instead of the solenoid valve. In this example, the auxiliary arm shaft 23
The wires 33 and 34 and the air pipe 35 are inserted through
The wirings 33 and 34 and the air pipe 35 are connected to the solenoid valve 36, and the air pipes 37 and 38 are led out from the solenoid valve 36 and connected to the robot hand 30. By doing so, the time lag (time delay) due to the air pressure supply time can be greatly reduced as compared with the conventional structure in which the solenoid valve is arranged in the second horizontal arm 12, so that the robot hand 30 A high-speed control operation can be achieved by avoiding a control delay.

In the embodiment described above, the rigidity of the main arm shaft can be increased by the support of the auxiliary arm shaft, so that the vibration of the robot working element such as the robot hand can be reduced and the positional accuracy can be improved. In addition, a remarkable effect that a high-speed operation can be achieved and a robot that can operate without any trouble even if the movement stroke of the main arm shaft in the axial direction is designed to be large can be achieved.

[0044]

As described above, according to the present invention, the auxiliary arm shaft extending parallel to the main arm shaft attached to the robot arm and mutually supported at least at two positions separated in the axial direction is provided. With the provision of the auxiliary arm shaft, the rigidity of the main arm shaft can be increased, and the vibration of the robot working element mounted on the mounting end at the tip of the main arm shaft can be suppressed and reduced. It is possible to configure a robot that can operate the arm at high speed and that can operate without any trouble even if the movement stroke of the main arm shaft in the axial direction is increased.

[Brief description of the drawings]

FIG. 1 is a schematic cut-away perspective view showing the entire structure (in a state where a main arm axis is lowered) of a horizontal joint type robot having an embodiment of a robot arm structure according to the present invention.

FIG. 2 is a schematic side view showing the entire structure of the horizontal joint type robot having the same embodiment (in a state where a main arm axis is raised).

FIG. 3 is a schematic plan view of a horizontal joint type robot provided with the embodiment.

FIG. 4 is a partial plan view showing a lower mutual support structure between a main arm shaft and an auxiliary arm shaft of the embodiment.

FIG. 5 is a partial perspective view showing an example of a wiring and piping arrangement structure in the embodiment.

FIG. 6 is a partial perspective view showing another example of a wiring and piping arrangement structure in the same embodiment.

DESCRIPTION OF SYMBOLS 10 Base shaft part 11 First horizontal arm 12 Second horizontal arm 13 Ball screw nut 14 Ball spline nut 15 Main arm shaft 15a Mounting end 16 Elevating drive motor 17 Rotation drive motor 21 Upper support plate 22, 25 Bearing 23 Auxiliary Arm shaft 24 Lower support plate 30 Robot hand 31, 32, 35, 37, 38 Air piping 33, 34 Wiring 36 Solenoid valve

Claims (8)

[Claims] 1. A robot arm structure comprising: a robot arm; and a main arm shaft which is attached to the robot arm so as to be movable at least in an axial direction and has a mounting end of a robot working element. An auxiliary arm shaft extending parallel to the arm axis is provided, and the main arm shaft and the auxiliary arm shaft are mutually supported directly or indirectly so as to maintain at least a mutual interval at least at two locations separated in the axial direction. An arm structure of a robot characterized by having been performed. 2. The robot according to claim 1, further comprising: a distal end side support portion that is provided near the mounting end of the main arm shaft and mutually supports the auxiliary arm shaft. An arm structure for a robot, wherein a mounting-side support portion for mutually supporting the auxiliary arm shaft is provided in the vicinity. 3. The mounting arm according to claim 1, wherein the auxiliary arm shaft is attached to the robot arm so as to be movable in the axial direction, so that an attachment side support portion is attached to the robot arm of the main arm shaft. And an auxiliary arm axis indirectly supported by the main arm axis via the robot arm. 4. One of claims 1 to 3
3. The arm structure for a robot according to claim 1, wherein the auxiliary arm axis is disposed near a base end of the robot arm with respect to the main arm axis. 5. The method according to claim 1, wherein:
3. The robot arm structure according to claim 1, wherein a plurality of the auxiliary arm axes are arranged in a moving direction of the robot arm with respect to the main arm axis. 6. Any one of claims 1 to 5
3. The robot arm structure according to claim 1, wherein the auxiliary arm shaft has a hollow structure, and wiring or piping for the robot working element is inserted into the auxiliary arm shaft. 7. One of claims 1 to 6
Item, wherein the main arm axis and the auxiliary arm axis are mutually supported in the vicinity of the mounting end via a support member connected to the main arm axis and the auxiliary arm axis. Arm structure. 8. The arm structure of a robot according to claim 7, wherein a driving element for the robot working element is fixed to the support member.