JPS6186159A - Hand-neck device of industrial robot - Google Patents

Abstract

PURPOSE:To permit an output end to perform desired hand-neck action by a combination of rotary movements, by obtaining three concentric rotary inputs to input ends and generating the rotary movements around three rotary axial centers including an axis diagonally crossing in one point. CONSTITUTION:The first hand-neck housing 16 receives the first rotary input rotating around the first axial center A. While the second hand-neck housing 18 receives the second rotary input via the first transmission gear mechanism 46, 48 and the first reduction gear 64, rotating around the second axial center B diagonally crossing with the first axial center A. Further a hand-neck output flange 30 receives the third rotary input via the second transmission gear mechanism 58, 62, third transmission gear mechanism 74, 78 and the second reduction gear 80, being able to rotate around the third axial center C passing through a crossing point of the first and the second axial centers A, B in relation to the second hand-neck housing 18. The end part of said hand-neck output flange 30 forms an output end 14.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a wrist device provided at the tip of a robot arm of an industrial robot, and particularly to a wrist device that performs wrist motion in three-dimensional space according to three concentric rotational inputs transmitted from the robot arm. The present invention relates to an internal structure of a wrist device having an output end.

In conventional industrial robots, a plurality of rotational inputs are introduced into the wrist via the robot arm, and the robot hand or various work tools attached to the output end of the robot are made to perform desired robot movements in a three-dimensional space. This configuration has been provided in the past. The wrist in such conventional industrial robots has a structure in which multiple sets of gear mechanisms are provided internally to combine multiple rotational inputs and cause the wrist output end to perform wrist movements in three-dimensional space. An example is JP-A-53
It is disclosed in Japanese Patent No.-83265. That is, the wrist of the industrial robot disclosed in this patent publication is provided in the wrist by introducing three rotational inputs decelerated in advance at the rear end of the robot arm to the input end of the wrist via the robot arm. The robot hand attachment part can be rotated at each point on a spherical surface larger than a hemisphere through a rotational transmission mechanism with a 3-axis coordinate system consisting of a bevel gear mechanism, and the 3-axis coordinate system is connected to each other at one point. It is formed by three intersecting rotation axes.

Problems to be Solved However, in the wrist structure of the above-mentioned known industrial robot, the shape of the bevel gear used in the bevel gear mechanism is complicated, and the assembly of these bevel gear mechanisms is relatively difficult. Moreover, there is a drawback that the mechanical errors of the bevel gear mechanism accumulate and affect the operational accuracy of the output end of the wrist portion, and there is a need for an improvement in the internal structure that can eliminate this problem. Accordingly, the present invention seeks to provide a wrist device for an industrial robot that has a mechanical structure that meets these needs and an internal structure that has sufficient mechanical rigidity to withstand external loads.

Solution and Effect According to the present invention, the robot arm has an input end into which three rotational inputs are concentrically input, and an output end through which the wrist moves in a three-dimensional space according to these three rotational inputs, A wrist device for an industrial robot having a robot hand or a work tool attached to an end thereof, the first wrist housing rotating around a first axis in response to a first rotational input;
A second rotational input is received via a first transmission gear mechanism and a first reduction gear, and is applied around a second axis obliquely intersecting the first axis with respect to the first wrist housing. A rotating second wrist housing and a third rotational input connected to the second wrist housing. Third
through a transmission gear mechanism and a second reduction gear; A wrist output flange that rotates around a third axis passing through an intersection of the second axis, and an end of the wrist output flange is formed at the output end. Second. The third transmission gear mechanism and the first transmission gear mechanism. The second speed reducer is connected to the two first speed reducers. Second
By incorporating it into the wrist housing, the external load applied to the output end of the wrist output flange is absorbed by both reduction gears, and the reduction gear also minimizes angular transmission errors due to backlash of the transmission gear mechanism. This is to maintain the operating accuracy of the output end at a high level. Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.

Embodiment FIG. 1 is a vertical sectional view showing the internal structure of an embodiment of the wrist device for an industrial robot according to the present invention, and FIG. 2 is a schematic mechanical diagram showing three rotational input systems.

In FIG. 1, the wrist device 1o has an input end 12 at one end, into which three rotational human forces α, β, and T are input from the robot arm side as described later. Further, the wrist device 10 has an output end 14 at the other end, and this output end 14 receives the three rotating human forces α.

When the wrist moves as described later in the three-dimensional space according to β and γ, a robot hand (not shown) or other working tool such as a welding gun or a painting gun is attached to the output end 14 by means of attachment means such as bolts and screws. It is possible to move the object to a desired position in space and give it a desired posture. Now, the wrist device 10 includes a first
wrist housing 16 and a second wrist housing 16 having the output end 14.
and a wrist housing 18, both of which are formed as substantially bowl-shaped hollow bodies, and are assembled so as to be relatively rotatable via a rotation bearing 20. Note that the second wrist housing 18
A Heath disc 24, which is separately formed and integrated by being fixed with screws 22, is attached inside, and an external cap 26 is also attached with screws or the like. Further, the second wrist housing 18 is integrally formed with a protrusion-shaped first bearing seat 28a in which a wrist output flange 30, etc., which will be described later, is accommodated.

Now, the first wrist housing 16 has a cylindrical portion 40,
This cylindrical portion 40 has a cylindrical shape that extends from a part of the bowl-shaped hollow body described above toward the robot arm, and its center axis coincides with the first rotation axis 68 of the wrist device 10. .

When this cylindrical portion 40 is coupled to a robot arm (not shown in FIG. 1) via an appropriate coupling means, rotational human force γ is applied to the first wrist housing 16, and the first wrist housing 16 Rotates around the first rotation axis A. Therefore, at this time, the second wrist housing 18 assembled via the rotation bearing 20 also rotates following the first wrist housing 16. Inside the cylindrical portion 40, a hollow rotating shaft 42 protruding from the robot arm side toward the input end 12 is provided coaxially with the cylindrical portion 40, and its inner end is connected to the cylindrical portion 40 with rotation bearings 44a, 44b. The shaft portion 46b of the cylindrical bevel gear 46 is fixedly connected to the shaft portion 46b of the cylindrical bevel gear 46 by a fixing method such as wedge attachment. All teeth 46a having a desired gear arrangement are formed at the inner end of the cylindrical bevel gear 46, and mesh with all cooperating teeth 48a. Therefore, the cylindrical bevel gear 46 rotates around the axis A by the rotational human force α input from the robot arm to the hollow rotating shaft 42. At this time, as described above, due to the meshing of all the teeth 46a and 48a, the rotational input α is transferred to the other cylindrical bevel gear 48 (
(having all teeth 48a). Here, the cylindrical bevel gear 48 is supported by a cylindrical bearing seat 50 formed in the first wrist housing 16 via rotary bearings 52a and 52b, and the rotation axis of the cylindrical bevel gear 48 and the second wrist housing The 18 rotation axes form a common second rotation axis B. In addition, the cylindrical bevel gear 48
The shaft portion 48b has a bottom plate 48C, and a transmission shaft 54 extends from the bottom plate 48c along the second rotation axis B into the second wrist housing 18, and is formed in the second wrist housing 18. The rotary bearings 56a, 56 are mounted on the second bearing seat 28b.
It is fixedly connected to a cylindrical bevel gear 58 attached via b by an appropriate fixing method such as a wedge bonding method or a press-fitting method. Furthermore, all the teeth 58a formed on the cylindrical bevel gear 58 are the same as all the teeth of a cylindrical bevel gear 62 rotatably attached to the first bearing seat 28 of the second wrist housing 18 via rotary bearings 60a, 60b. It meshes with 62a. Moreover, the outer end of the shaft portion 62b of the cylindrical bevel gear 62 is connected to an input wheel 64a of a reduction gear device 64 having a high reduction ratio. The output wheel 64b of the speed reduction device 64 is connected to the inner end of the wrist output flange 30.
As described above, the arm itself is rotatably attached to the first bearing seat 28a of the second wrist housing 18 via rotary bearings 68a, 68b. In this way, the cylindrical bevel gear 46
, 48, a transmission gear mechanism also consisting of cylindrical bevel gears 58, 62, and a coaxial reduction gear 64 having a high reduction ratio are provided in the first and second wrist housings 16, 18. As described above, the rotational human power α transmitted to the cylindrical bevel gear 46 has its transmission direction changed by these two transmission gear mechanisms, and is also transmitted to the reduction gear 6
4 and is transmitted to the wrist output flange 30, causing the wrist output flange 30 to rotate around the third rotation axis C. Note that the reduction ratios of the two transmission gear mechanisms described above can be selected at an appropriate level taking into consideration that the reduction ratio of the reduction gear device 64 has a sufficiently large value (for example, 1:100), and All the teeth 46a, 48a, 58a, 62a, etc. may be formed with appropriate dimensions in consideration of the size of the internal space of the second wrist housings 16, 18. Further, the well-known harmonic drive speed reducer (trade name) may be used as the speed reducer 64 having a high speed reduction ratio.

In addition to the rotational human power α and γ described above, a third rotational human power β introduced from the robot soto arm side is applied to the inner shaft 70 provided inside the hollow rotation shaft 42 .

That is, the outer end of the inner shaft 70 is connected to the robot arm, and the inner end is connected to the shaft of a cylindrical bevel gear 74 of substantially the same shape that is provided concentrically inside the cylindrical bevel gear 46 via rotary bearings 72a and 72b. The cylindrical bevel gear 74 is fixedly connected to the portion 74b by an appropriate fixing method such as a molding method or an adhesive method, and rotational human power β is transmitted to the cylindrical bevel gear 74.

All teeth 74 formed on the inner end of this cylindrical bevel gear 74
a is a rotating bearing 7 inside the cylindrical bevel gear 48 mentioned above.
It is meshed with all teeth 78a of a cylindrical bevel gear 78 which is rotatably mounted via gears 6a and 76b. The shaft portion 78b of the cylindrical bevel gear 78 extends inward from the bearing seat 50 side along the second axis B inside the first wrist housing 16, and the inner end has a high reduction ratio. It is coupled to the input wheel 80a of the coaxial reduction gear 80. Further, the output wheel 80b of the coaxial reduction gear 80 is coupled to the base disc 24 of the second wrist housing 18 described above.

Therefore, as described above, the rotating human power β transmitted to the cylindrical bevel gear 74 is transmitted to the cylindrical bevel gear 78 by the meshing of all the teeth 74a and 78a, and then is decelerated at a large reduction ratio via the reduction device 80, and then The power is transmitted to the second wrist housing 18 via the disc 24, causing it to rotate around the second rotation axis B. At this time, it goes without saying that the wrist output flange 30 also rotates at the same time.

The second rotational axis B intersects the first axis A obliquely at a point P, and the rotational axis C ( The third rotation axis) also intersects. In Figure 1, 1. Although it is shown that the third rotation axes A and C are aligned,
When the second wrist housing 18 rotates around the second rotation axis B, the first to third rotation axes A, B, and C face different directions and intersect at the intersection P. 6
As is clear from the above description, when three rotational forces α, β, and γ that are concentric and mutually independent with respect to the first rotation axis A are inputted from the input end 12, the wrist output flange 30 rotation around the third rotation axis C by the second wrist housing 18, rotation around the second rotation axis B by the first wrist housing 16, and rotation around the first rotation axis A by the first wrist housing 16. By the combination of these three rotations, the output end 13 formed at the outer end of the wrist output flange 30 performs multiple operations in three-dimensional space, that is, ``moves to a desired position in 33-dimensional space; The posture setting at the position is performed. As mentioned above, the rotation of the second wrist housing 18 and the rotation of the wrist output housing 30 are controlled by coaxial reduction gears 80 and 64 (both of which are formed by the well-known Harmonic Drive reduction gear (trade name)) having a high reduction ratio. Therefore, transmission errors due to bank lash, etc. in the three sets of transmission gear mechanisms using the cylindrical bevel gear described above are reduced by the two reduction gears 80,
This is substantially absorbed by the deceleration effect of 64, thus achieving highly accurate rotational transmission. Note that the rotational human power γ is formed as a rotational input that is previously input from the robot arm and subjected to a deceleration effect.

In FIG. 1, reference numeral 82 denotes a presser foot for the rotary bearing 20, which is fixed to the first wrist housing 16 with a screw 84. Further, 86 is a cap.

Figure 2 shows the transmission system of the three rotating human forces α, β, and T mentioned above via the drive motor and the robot arm.
The driving motor 90 is a driving means that generates rotational human power α through a transmission gear mechanism 96 and a center shaft 98 of the robot arm. Further, the driving motor 92 is a driving means for generating rotating human power β by the inner shaft 102 of the robot arm via a transmission gear 100, and the driving motor 94 is rotated by the outer shaft 108 of the robot arm via a reduction gear 104 and a transmission gear 106. These three driving motors 90, 92, and 94, which are driving means for generating human power T, are controlled by a well-known control device included in the industrial robot. For example, each is configured by a DC servo motor or the like. Note that the speed reduction device 10 provided on the output shaft of the drive motor 94 described above
4 may also be formed by the No. 1-Monic Drive Reduction Device (trade name) having a high reduction ratio as described above. The outer shaft 108, middle shaft 98, and inner shaft 102 of the robot arm described above are connected to the cylindrical portion 40 of the wrist device 10 described above, respectively.
, the hollow rotating shaft 42, and the inner shaft 70.

Effects of the Invention As is clear from the above explanation, the wrist device of the industrial robot 1 according to the present invention receives three concentric rotational inputs at the input end, thereby achieving three rotations including oblique axes intersecting at one point P. Rotation occurs around the axis, and the combination of these rotations causes the output end to perform the desired wrist movement in three-dimensional space.At this time, a transmission gear mechanism consisting of a bevel gear for changing the rotation direction and a high reduction ratio are used. Since the deceleration device is built into the wrist device itself, the influence of the load applied to the output end is absorbed by these deceleration devices, and the robot arm side is not greatly affected, so the machine seen from the output end side This has the advantage that it is formed as a wrist device with extremely high physical durability.

Furthermore, since the rotating human forces α and β are transmitted to the rotated member through the transmission gear mechanism and further through the reduction gear with a high reduction ratio, transmission errors due to punctures, wheels, etc. that are present in the transmission gear mechanism can be sufficiently reduced. and is transmitted to the rotated member. As a result, it is also possible to maintain the transmission accuracy at a high level.

Furthermore, the cylindrical bevel gears that form the above-mentioned transmission gear mechanism are all marked (, 1
Since it is a - shaped bevel gear, it also has the advantage of reducing costs and making it easy to maintain machining accuracy.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view showing an embodiment of the internal structure of a wrist device for an industrial robot/nod according to the present invention, and FIG. 2 is a schematic mechanical diagram showing the generation and transmission system of rotational input. α, β, T...Rotation input, A, B, C...Rotation axis center, 10...Wrist device, 12...Input end, 14...
・Output end, 16...First wrist/'% housing, 18...Second wrist housing, 30...Wrist output flange, 46, 48, 5B, 62, 74, 78...
- Cylindrical bevel gear, 64, 80... High reduction ratio reduction device, 90, 92, 94... Drive motor.

Claims (1)

[Claims] 1. An input end into which three rotational inputs are concentrically input from a robot arm, and an output end through which the wrist moves in a three-dimensional space according to the three rotational inputs, A wrist device for an industrial robot to which a robot hand or a work tool is attached, the first wrist housing rotating about a first axis in response to a first rotational input; a transmission gear mechanism; and a second wrist housing that is received via the first reduction gear and rotates about a second axis obliquely intersecting the first axis with respect to the first wrist housing. , receives a third rotational input via the second and third transmission gear mechanisms and the second reduction gear, and passes through the intersection of the first and second axes with respect to the second wrist housing. 3. A wrist device for an industrial robot, comprising: a wrist output flange rotatable around a third axis; and the output end is formed at an end of the wrist output flange. 2. The first and second wrist housings are formed of two bowl-shaped hollow bodies connected to each other via rotation bearings, and the first, second, and third transmission mechanisms and the The wrist device for an industrial robot according to claim 1, wherein the first and second deceleration devices are built-in and held. 3. The first, second, and third transmission mechanisms are each formed by a bevel gear mechanism for changing the transmission direction, and the first and second reduction devices are each formed by a coaxial reduction device having a high reduction ratio. A wrist device for an industrial robot as claimed in claim 1 or 2. 4. The two bevel gear mechanisms forming the first and second transmission mechanisms include two coaxially arranged input bevel gears and two coaxially arranged output bevel gears meshing with these two input bevel gears. Claim 3
Wrist device for industrial robots as described in Section.