JP2629920B2 - Industrial robot - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an industrial robot used as an assembling unit in an assembling process at a factory site, for example.

[Related Art] An assembling robot has, for example, a function of moving in a vertical direction together with a turning motion and a telescopic motion corresponding to one horizontal plane. Such a three-dimensional movement can be constituted by, for example, one multi-articulated arm. However, it is difficult to improve the positional accuracy of the working head in the horizontal and vertical directions. And become more expensive. For this reason, there is a demand for the development of a robot that is structurally simple and capable of performing operations with high precision. For example, a movable portion is configured by combining four connecting arms. An example of such a robot is considered as shown in FIG. 2 of JP-A-59-97861.

That is, the four connecting arms are sequentially connected by the four rotating nodes to form a quadrilateral, and are divided into two hands around the rotating node that forms the root rotating node. The set relative angular position of the two connecting arms is set by at least two servomotors. Then, a working jig such as a chuck which is set to be moved in the vertical direction is attached to another rotating node portion at a diagonal position of the root rotating node, and the working jig is arbitrarily set by the servo motor. It is conceivable that the position is set to move to, for example, an assembly operation or the like is performed at that position. However, in such a connecting arm structure, an offset is generated between the two connecting arms at the other rotating node at the diagonal position, and the axis of the other rotating node becomes long.

In the robot configured as described above, the rigidity of the work jig in the planar direction differs depending on the form of the four connecting arms. In particular, the rotary joint on which the work jig is set is located farthest from the root joint. In one form, the rigidity in the direction of rotation about the root joint is the smallest.

Therefore, when assembling work or the like is performed using such a robot, the positions of the parts and the like held by the jig portion are determined, and the assembling work is performed, the rigidity in the rotational direction is low as described above. Therefore, it is difficult for the jig portion to converge within the target stop accuracy in an attempt to stop. In particular, both arms are twisted due to the offset, which makes it more difficult to determine the position of the jig.

When the robot having such a configuration is used in a horizontal position, the four connecting arms move in a vertical plane. In this case, the weight of the work jig becomes a serious problem.For example, when the work jig is a chuck and a heavy component is held by the chuck, a large weight load is applied to the drive rotary joint. And each of the connecting arms experiences a displacement that changes position in a vertical plane. That is, there is also a problem that a minute rotational displacement occurs in the rotating node in accordance with the change in the weight of the chuck portion, and the chuck portion deviates from the target stop position, causing an error in the position.
In particular, the connecting arms are twisted relative to each other due to the offset. In particular, when the other rotary joint of the long shaft at the diagonal position is tilted, the error of the chuck unit is further increased.

[Problems to be Solved by the Invention] The present invention has been made in view of the above points, and in order to increase rigidity without increasing the weight in particular, the use of the above-described jig portion and the like, particularly without using the offset. The purpose of the present invention is to provide an industrial robot in which the position of the robot can be easily determined.

[Means for Solving the Problems] In the industrial robot according to the present invention, one ends of the first and second connecting arms are set at coaxial positions,
Servo motors with brakes are set in the first and second rotational nodes, respectively, to form driving rotational nodes. The third and fourth connecting arms are connected to each other by setting the third and fourth rotating nodes at the distal ends of the first and second connecting arms, respectively. A working jig is provided by forming a fifth rotating node at the tip of the work. Then, a brake mechanism is set at the third and fourth rotary joint portions. Here, the first connection arm and the third connection arm, and the second connection arm and the fourth connection arm
Are set at the third and fourth rotary joints that connect each other, and the third connection arm and the fourth connection arm are set close to each other.

[Operation] That is, in the industrial robot as described above,
The first and second connecting arms are rotationally driven by the servomotors set on the first and second rotary joints, and the working jig set on the distal ends of the third and fourth connecting arms is moved. It will be swiveled in one plane. Then, when stopping, the rotation operation at the first and second rotating nodes is performed by stopping the servomotor and applying the brake. At the time of this stopping operation, the brake mechanisms set at the third and fourth rotating nodes are also operated, and the rotating operations at the respective rotating nodes are simultaneously restrained. At this time, the rigidity of the connecting arm in the plane is sufficiently set, and the stop of the work jig is controlled without setting the decay time. In particular, since the third connection arm and the fourth connection arm are set close to each other, the offset between the third connection arm and the fourth connection arm for attaching the jig is small. Become.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIGS. 1 and 2 show the structure of the robot. The robot has, for example, a box-shaped base 11, on which a column 12 forming a base together with the base 11 is integrally formed. Installed. This column 12
Support member 12 facing the horizontal upper surface of base 11
The support member 121 has the base
A first rotating shaft 13 is provided to be vertical in the direction of 11. A second rotating shaft 14 is set on the base 11 such that a tip of the rotating shaft 13 is opposed to a lower end of the rotating shaft 13. The first and second rotating shafts 13 and 14 provide a first rotating shaft. And the second rotary joints 15 and 16 are formed. Then, the first and second rotation nodes 15
And 16 include first and second connecting arms 17 respectively.
The first and second connecting arms 17 and 18 are arranged so as to be overlapped in the vertical direction.

Here, the first and second rotating shafts 13 and 14 are coaxially provided with servomotors 19 and 20, respectively.
Speed reducers 192 and 202 are provided, and the motors 19 and 20 have brake mechanisms 191 and 201, respectively. A receiving hole 141 is formed at the tip of the second rotary shaft 14.
And the front end portion 131 of the first rotating shaft 13 is fitted into the receiving hole 141 so as to be coaxially held in a rotatable state.

The first and second rotary joints 15 and 16 to which the first and second connecting arms 27 and 28 are attached are, as is clear from the drawing, close to the end portion close to the column 12 and close to the base 11, respectively. It is formed in a trapezoidal cross section in which the direction of the end is large.

That is, the first and second connecting arms 17 and 18
Are coupled to the first and second rotary joints 15 and 16, respectively, and are supported by the servomotors 19 and 20 so as to be rotated in a horizontal plane, respectively.

The first and second connecting arms 17 and 18 respectively have free rotating ends, and the third and fourth rotating nodes 21 and 21 are respectively provided by rotating shafts set in a vertical state.
22 is formed, and the third and fourth connecting arms 28 and 24 are rotatably connected to the rotating nodes 21 and 22. The third and fourth connecting arms 23 and
The respective distal ends of 24 are rotatably connected by a fifth rotary joint 25. Here, the third connecting arm 23 has a step set with respect to the first connecting arm 17, and the fourth connecting arm 24 has a step set with respect to the second connecting arm 18. The fourth connecting arms 23 and 24 are set close to each other, and are in a state where they are overlapped with each other at the fifth rotating section 25. Then, a chuck mechanism 26 serving as a working jig is attached and set to a distal end portion of a fourth connecting arm 24 further extending from the fifth rotating node 25.

The chuck portion 26 serving as the work jig includes a screw 261 set and held in a vertical state, and the screw 261
And a vertical slider 263 is screwed onto the screw 261. And
Although not shown in this drawing, a chuck is appropriately attached to the slider 263, and the slider 263 is moved in the vertical direction by rotating the screw 261 by the servo motor 262, and the chuck is moved in the vertical position. To be set.

FIG. 3 shows a first connecting arm 17 and a third connecting arm 23.
The first connecting arm 17 has a rotating shaft 211 attached vertically to the distal end of the first connecting arm 17, and the shaft 211 is connected to a set screw 21.
2, 213 fixedly set to the first connecting arm 17. The end of the third connecting arm 23 is rotatably attached to the rotating shaft 211 so that the first and third connecting arms 17 and 23 are connected to each other in a rotatable state. become.

A brake mechanism 27 is provided at a tip end of the rotation shaft 211. The brake mechanism 27 includes a stator 271 integrally connected to the third connecting arm 23 and an armature integrally connected to the rotation shaft 211. A hub 272 is provided, and the armature 273 attached to the armature hub 272 is selectively coupled to the stator 271 by magnetic attraction.

That is, when the armature 273 is coupled to the stator 271, the rotating shaft 211 and the third coupling arm 23 are integrally coupled, and the first coupling arm 17
A braking force acts on the pivoting motion between the first and second connecting arms 23, and the angular positional relationship between the first and second connecting arms 17 and 23 is fixed.

FIG. 4 shows a specific example of the brake mechanism 27.
The stator 271 has a flange mounted and fixed on the upper surface of the third connection arm 23, and a magnetic coil 274 is provided inside. A lining 275 is fixedly set on a portion of the magnetic coil 274 facing the armature 273.

The armature hub 272 has a cylindrical portion fitted into the tip of the rotating shaft 211, and a key groove for inserting a key for preventing rotation with the rotating shaft 211 is formed on the inner surface of the cylindrical portion. . An armature 273 made of, for example, a ring-shaped magnetic material is attached to a portion of the armature hub 272 facing the stator 271 so as to be movable in the direction of the stator 271.

That is, when an exciting current is supplied to the magnetic coil 274 from an electric circuit set outside, the armature 273 is suction-coupled to the lining 275, the stator 271 and the armature hub 272 are integrally coupled, and the first Connecting arm 17
Third rotary joint 21 which is a connecting portion between the first rotating arm 21 and the third connecting arm 23
The braking force acts on the part.

Although not particularly shown, a similar brake mechanism 28 is provided in the fourth rotary joint 22 that connects the second connecting arm 18 and the fourth connecting arm 24.

That is, in the robot configured as described above, the first and second connecting arms 17 and 18 are respectively positioned by rotating the first and second servo motors 19 and 20 with brakes by a set amount, respectively. It is rotated by a fixed amount and rocked in a horizontal plane. Therefore, the third and fourth connecting arms 23 and 24 connected to the connecting arms 17 and 18 are also driven to swing. Then, by the swinging operation of the connecting arms 17, 18 and 23, 24 by the servo motors 19, 20, the chuck mechanism 26 can be arbitrarily moved within the area A shown in FIG.

When stopping after performing such a rocking operation, the driving force by the servomotors 19 and 20 may be cut off, but at the same time, the brake mechanisms 191 and Activate 201,
The first and second connecting arms 17 and 18 are restrained with respect to the base 11 and the column 12, respectively.

In this case, at the same time, the third and fourth rotary joints 21 and 22
The brake mechanisms 27 and 28 respectively set in the sections also give an operation command from an external circuit mechanism, that is, the excitation coil 27
4 to the first and second connecting arms 1
Third and fourth connecting arms 2 for 7, 18 respectively
3, so that the rocking movement of 24 is restrained.

That is, when the component or the like chucked by the chuck mechanism 26 is to be positioned at a predetermined portion and an operation such as insertion of the component is to be performed, the first and second servo motors 19 and 20 are used to perform the first and second operations. The second connecting arms 17 and 18 are rotated, and the third and fourth connected arms are rotated.
By moving the connecting arms 23 and 24 of the
Is moved to the position to be positioned. When the chuck mechanism 26 reaches the predetermined position, the servomotors 19 and 20 are stopped, the brake mechanisms 191 and 201 are operated, and the brakes of the third and fourth rotating sections 21 and 23 are braked. Activate mechanisms 27 and 28.

When the braking operation is performed in this manner, the first to fourth braking operations are performed.
The rigidity of the connecting arms 17, 18, 23, 24 in the horizontal plane direction is increased, and the vibration damping time of the chuck mechanism 26 is shortened.

In the above embodiment, the connecting arm portion is in the vertical position in which the connecting arm portion swings in a horizontal plane. The weight of the mechanism 26 acts directly on the direction of the swinging motion of the connecting arm, making it difficult to increase the positioning accuracy. However, with the above-described configuration, the displacement error due to the influence of the change in the weight of the work portion or the load in the planar direction can be effectively reduced.

[Effects of the Invention] As described above, according to the industrial robot according to the present invention, particularly, in which four connecting arms are used in combination,
When the rocking motion is performed in one plane, the shapes of the first and second rotary nodes are devised, and the third and fourth connecting arms extending from the first and second rotary nodes are connected to each other. Since they are set close to each other, the rigidity in the direction of the surface is effectively improved, and at the time of the stopping operation, the stopping characteristic of the work jig is improved. Therefore, the positioning and the like are smoothly performed, and a great effect is exhibited in the efficiency of the assembling work by the robot. At the same time, the positional accuracy is easily improved, and the function as the assembling robot is improved. Things. Also, there is no need to increase the size or increase the weight in order to increase the rigidity.

[Brief description of the drawings]

FIG. 1 is a side view of an industrial robot according to an embodiment of the present invention, FIG. 2 is a plan view of the robot, and FIG. 3 is a third view of the robot. FIG. 4 is a cross-sectional view showing a rotary joint portion taken out of FIG. 11… Base, 12… Column, 13, 14… Rotating axis, 15,
16 first and second rotary joints 17, 18 first and second connecting arms 19, 20 first and second servomotors with brakes 21, 22, third and second Fourth rotary joint, 23, 24 ... third and fourth connecting arms, 25 ... fifth rotary joint, 26 ... chuck mechanism, 27, 28 ... brake mechanism.

Claims (1)

(57) [Claims] 1. A base, first and second rotary joints arranged coaxially on a part of the base, and one end of each of the first and second rotary joints is connected to the first and second rotary joints. First and second connecting arms connected to each other and rotated in a state parallel to one plane; and third and fourth connecting arms provided at the other ends of the first and second connecting arms, respectively. And one end of each of them is connected to the third and fourth rotary joints, respectively, to form first and second arm systems together with the first connecting arm and the second connecting arm, respectively. A third and a fourth connecting arm, and a third and a third arm respectively constituting the first and the second arm systems.
And a fifth rotating joint portion, the tip of which is rotatable and commonly connected to each other, and whose position is determined by the first and second arm systems; and A drive source with a brake for rotating the second arm system and moving the fifth rotary node to a predetermined position, wherein the first rotary node and the second rotary node include: The surfaces on the base side opposite to the surfaces facing each other are configured to be larger in diameter than the surfaces facing each other.
Are connected so as to form a step with respect to the first and second connection arms, so that the third connection arm and the fourth connection arm are set close to each other. Features industrial robots.