JPH09109082A - Joint structure of industrial robot - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain machining of joint structure of a robot body easily with high accuracy so as to reduce machining cost. SOLUTION: In the joint structure 24 of an industrial robot, an area of the fitting bearing surface 20b of a movable element 20 to which a coaxial type speed reducer 28 is fitted, is secured as the high accuracy surface by simple facing. The end face of the speed reucer 28 is brought into contact with the high accuracy bearing surface 20b, and the peripheral part of an outer ring 36 of a main bearing 34 is closely fitted and positioned into a fitting hole bored by precision machining in the side face 20b of the movable element 20. The fitting of the speed reducer 28 by socket and spigot jointing is thereby attained so as to be coaxially direct-coupled with high accuracy to an output shaft 26 of a driving motor M.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a joint structure of an industrial robot, and more particularly to a structure in which a drive motor and a coaxial speed reducer are installed in series in a joint portion of two movable elements to provide a space between the two movable elements. The present invention relates to a joint structure of an industrial robot capable of easily and highly accurately processing a joint structure that causes relative rotation.

[0002]

2. Description of the Related Art A joint part of an industrial robot, for example, a joint part that connects two movable elements of a first arm and a second arm of a multi-joint type robot body, has a rotation attached to one movable element. The output element of a planetary speed reducer or other well-known coaxial type speed reducer in which the rotary output shaft of a drive motor composed of a servo motor with a detector is attached to the same movable element, and the output element of the drive motor is connected to the other movable element. A configuration is widely used in which the rotational output is decelerated and transmitted, and the latter driven movable element is rotated a predetermined amount around the joint axis.

FIG. 4 shows a conventional example of a joint portion provided between two movable elements, which is provided as a joint portion 50 between a first arm 51 and a second arm 52 of a robot body. ing. In this joint 50, the first arm 5
A drive motor 53 forming an actuator for the joint is attached to the left side of 1 by an attaching means such as a bolt screw, and the drive motor 53 has an output shaft 54.
A coaxial type speed reducer 55 is attached to the other side of the first arm 51, and the speed reducer 55 has an input shaft 5 to which a rotational input is applied.
6 and an output shaft 57 for outputting decelerated output rotation, the input shaft 56 is coupled to the output shaft 54 of the drive motor 53, the reducer output shaft 57 is coupled to the second arm 52, and the second arm 52 is a joint part 50 relative to the first arm 51.
It is configured to rotate around the axis of.

In this case, the coaxial speed reducer 55 is fitted into the seat surface 59 formed at the end of the first arm 51 at the right-angle end surface of the outer casing 58 of the machine body in a substantially close-fitting state (so-called spigot state). And the speed reducer 55 is positioned. That is, the outer diameter of the outer box 58 of the speed reducer 55 and the inner diameter of the seat surface 59 are tightly fitted, and the end surface of the speed reducer is brought into contact with the seat surface 59. In this way, the reduction gear 55 is fitted and positioned in the seating surface 59 cut on the side surface of the first arm 51 in the spigot state, and thus the drive motor 53 and the coaxial reduction gear 55.
A highly accurate coaxial coupling between the robot body and the robot body is achieved, and therefore, the motion accuracy of the joint portion 50 of the robot body can be established with high accuracy.

[0005]

However, according to the conventional structure of the joint portion 50, the annular shoulder portion is precisely excavated when processing the seat surface 59 on which the coaxial reduction gear 55 is fitted in the spigot state. Since it is necessary, long-time machining using a small-diameter end mill tool or the like is required, and since the shoulder portion exists in a stepped shape, the seat surface 59 with which the end face of the reducer abuts must first be face mill or the like. However, the relatively large diameter cutting tool for surface machining cannot be efficiently and rapidly cut at a stretch. As a result, there is a problem in that the number of machining of the joint portion 50 is increased and the cost is increased.

Further, the coaxial type speed reducer 5 which abuts on the seat surface 59.
In the case of the speed reducer in which the corner chamfer of the end face of 5 is formed small, the end face of the speed reducer 55 having the above small corner chamfer is located at the inner corner of the seat face 59 side of the movable element 51. It is extremely difficult to perform machining so as to be correctly positioned on the seat surface 59, and the method of forming a relief corner portion or the like imposes a burden such as performing a special cutting process while exchanging tools. As a result, the problem of cost increase due to the increase in man-hours is further expanded.

Therefore, an object of the present invention is to improve the structure of the joint portion of such a conventional robot body to simplify the processing and to reduce the manufacturing cost by reducing the man-hours.

[0008]

SUMMARY OF THE INVENTION In view of the above-mentioned object, the solution of the present invention is to provide a high-accuracy surface by a simple surface-cutting process for a mounting seat surface area of a movable element on which a coaxial reducer is mounted. As a result, the end surface of the speed reducer is brought into contact with the high-precision seating surface, and the outer ring peripheral portion of the main bearing provided inside the speed reducer is tightly fitted and positioned in the mounting hole drilled in the movable element. This achieved a spigot mounting of the reducer, enabling highly accurate coaxial direct coupling with the output shaft of the drive motor.

That is, according to the present invention, the rotation output from the drive motor is directly connected to the joint joint of the two movable elements of the industrial robot, and the deceleration output of the coaxial reducer is received. In a joint structure of an industrial robot that transmits power to a movable element of a driving body, an outer ring of a main bearing built inside the coaxial type reduction gear interposed between the two movable elements has an outer ring of the two movable elements. The input shaft of the coaxial reduction gear and the motor output of the drive motor which are fitted and positioned in a fitting hole formed in the central region of the flat contact surface cut in one of the movable elements. The joint structure of an industrial robot is configured to be coaxially coupled with an axis.

According to the above-mentioned structure, since the mounting end surface of the coaxial type speed reducer is brought into close contact with the flat contact surface of the movable element of the robot machine while being closely fitted and positioned in the fitting hole, the speed reducer is the same. Is attached to the movable element in the spigot state, and if the structure of the joint is such that the drive motor is directly connected to the speed reducer positioned in this way, the operating accuracy of the movable element at the joint can be maintained at high accuracy. In addition, for the machining of joints, the flat contact surface can be precisely and easily machined with a large-diameter tool such as a face mill, and the fitting hole is boring with a milling tool of the required diameter. Therefore, it is possible to perform high-precision machining with a low man-hour, and it is possible to reduce the machining cost.

The fitting hole of the movable element into which the outer ring of the main bearing of the reduction gear is fitted may be a straight hole or a structure having a large diameter escape hole inside the straight hole. The required high-precision fitting hole can be obtained by the high-speed feed of the boring tool and the relatively short drilling process.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will now be described in more detail based on the preferred embodiments shown in the accompanying drawings. FIG. 1 is a sectional view showing a joint structure of an industrial robot according to an embodiment of the present invention, in particular, a form in which the present invention is applied to a joint portion between two robot arms, and FIG. 2 is a main portion thereof. FIG. 3 is an enlarged sectional view, FIG. 3 is a schematic perspective view showing the overall structure of an articulated industrial robot suitable for using the joint structure according to the present invention, and FIG. 4 is a sectional view showing the structure of a conventional joint. is there.

First, referring to FIG. 3, a body of an articulated industrial robot is generally shown. The robot body 10 includes a stationary base 1 fixed to a floor or the like.
2. A swivel pedestal 14 that is erected on the base 12 and is capable of swiveling about a vertical axis, and a top portion of the swivel pedestal 14 is a joint portion
The first robot arm 16 is rotatable about a horizontal axis by pivotally attaching the lower end as a, and the base end is pivotally attached by using the tip end of the first robot arm 16 as the joint portion 16a. A second robot arm 18 etc. that can rotate about an axis parallel to the horizontal axis of
The robot arm 18 has a wrist at a joint (not shown) at the tip thereof, and various end effectors are attached to the wrist to perform a desired robot operation.

Here, the joint structure according to the present invention can be applied to the joint portions 14a and 16a, thereby reducing the number of man-hours while maintaining high accuracy in manufacturing and processing the joint portions 14a and 16a. Therefore, the cost can be reduced. In FIG. 3, M1, M2
Represents a drive motor for the first and second robot arms 16 and 18, and rotationally drives the first robot arm 16 or the second robot arm 18 which is a driven body via a coaxial type speed reducer (not shown). It is a thing.

Referring now to FIG. 1, for example, the first
An embodiment is shown in which the present invention is applied to a joint portion 24 formed between a robot arm as one movable element 20 and a second robot arm as another movable element 22 and its proximal end. There is. The joint portion 24 fixes the drive motor M to the side surface 20a at the end of the first movable element 20 so that the motor output shaft 26 faces the inside of the first movable element 20.
Further, one end face and the input end face side of the coaxial reducer 28 are fixed in contact with the other side face 20b of the end portion of the first movable element 20. At this time, an input unit 30 directly connected to the motor output shaft 26 of the drive motor M is provided at the input end of the speed reducer 28 facing the inside of the first movable element 20, and the input unit 30 includes the gear mechanism 32. The motor output is introduced into the speed reducer 28 via the speed reducer 28, and the motor output is decelerated and used as a deceleration output.
2 has a configuration for transmitting. At this time, the output shaft 26 of the drive motor M and the input portion 30 of the coaxial speed reducer 28 need to be coaxially and concentrically coupled with high precision. For this reason, the speed reducer 28 is attached and positioned in advance. Higher accuracy is required.

Therefore, according to the present invention, the first movable element 2
The side surface 20b of 0 is preliminarily cut into a highly accurate flat seating surface,
A large diameter hole 20c is formed in the flat seating surface of the side surface 20b, for example,
High precision drilling is performed with a milling cutter or the like, and one main bearing 34 provided inside the coaxial reduction gear 28 is projected into the large diameter hole 20c, and the outer peripheral surface of the outer ring 36 thereof is in a spigot state. The shaft-hole fitting structure is adopted, and the end surface 28a of the speed reducer 28 is brought into contact with the flat side seat surface 20b as shown in FIG. 2 to achieve highly accurate positioning fitting. At this time, the output end 38 of the speed reducer 28 is connected to the second movable element 22 which is a driven body to drive the drive motor M,
The common axis line Mp directly connected to the speed reducer 28 is used as the axis line of the joint portion 24 so that the reduction gear 28 can rotate.

FIG. 2 is an enlarged view of the area indicated by A in FIG. 1, which shows in detail the mounting and positioning of the speed reducer 28 described above. According to the above-described structure, when mounting the speed reducer 28, the side surface 20b of the first movable element 20 is machined such that the side surface 20b is formed into a flat surface and the large diameter hole 20c perpendicular to the flat surface is formed. Is not provided, and there is no shoulder structure portion as shown in FIG. Therefore, the former surface processing uses a well-known face mill to quickly create a large flat seating surface area,
Easy and highly efficient cutting is possible. Besides, large diameter hole 2
The drilling of 0c can be performed with high accuracy and efficiency by the boring cutter for boring. As a result, the number of man-hours is significantly reduced in the machining process, and the tool replacement basically only requires the replacement of the face mill for surface machining and the boring cutter, which makes machining highly efficient. Needless to say, it is possible to make progress and, as a result, a reduction in processing cost can be obtained.

Further, as for the speed reducer 28, in the conventional method, the outer diameter of the speed reducer itself needs to be cut or ground for the spigot fitting, but according to the present invention, the precise bearing outer ring 36 is used. Since the fitting and the positioning are established by utilizing the above, it is possible to ensure the convenience that the processing on the speed reducer 28 side is not necessary at all. The above-mentioned first and second movable elements 20 and 22 may be the first and second robot arms 16 and 18 shown in FIG. 3, or the swivel pedestal 14 and the first robot arm 16 may be used. It may be.
Further, those skilled in the art can easily understand that the joint between the stationary base 12 and the swivel pedestal 14 can be applied.

[0019]

According to the present invention, in the joint structure of the industrial robot, the mounting seat surface area of the movable element on which the coaxial type speed reducer is mounted is secured as a highly accurate surface by simple surface cutting, and the deceleration is achieved. Deceleration by abutting the end face of the machine with its high-precision seating surface and by tightly fitting and positioning the outer ring periphery of the main bearing inside the speed reducer into the precision machined mounting hole drilled in the movable element. The machine's spigot fitting was achieved, and highly accurate coaxial direct coupling with the output shaft of the drive motor was possible. Therefore, it becomes possible to facilitate the machining in the manufacturing and manufacturing of the joint structure and reduce the number of man-hours. Therefore, it is possible to reduce the processing cost of the joint part of the industrial robot and the processing cost of the entire robot body. To play.

In this way, of course, it is possible to improve the motion accuracy of the robot, especially the joints, which is obtained by highly accurate manufacturing and processing, and thus the motion of all the motions of the robot when performing a predetermined robot motion according to a desired program. It is clear that the accuracy is also improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a joint structure of an industrial robot according to an embodiment of the present invention, in particular, a form in which the present invention is applied to a joint portion between two robot arms.

FIG. 2 is a partially enlarged sectional view of a portion A of FIG.

FIG. 3 is a schematic perspective view showing an overall configuration of an articulated industrial robot suitable for using the joint structure according to the present invention.

FIG. 4 is a sectional view showing the structure of a conventional robot joint.

[Explanation of symbols]

 10 ... Robot body 12 ... Stationary base 14 ... Revolving base 14a ... Joint part 16 ... 1st robot arm 16a ... Joint part 18 ... 2nd robot arm 20 ... 1st movable element 20b ... Side part 20c ... Large diameter hole 22 ... second movable element 24 ... joint portion 26 ... output shaft 28 ... coaxial speed reducer 28a ... end face 30 ... input portion 34 ... main bearing 36 ... outer ring 38 ... output end

Claims (1)

[Claims] Claim: What is claimed is: 1. A rotary output from a drive motor is directly connected to a joint joint of two movable elements of an industrial robot, and the deceleration output of the coaxial type speed reducer is used as a movable element of a driven body. In a joint structure of an industrial robot that is transmitted to a vehicle, an outer ring of a main bearing built inside the coaxial type speed reducer interposed between the two movable elements is a movable element of one of the two movable elements. It is fitted and positioned in a fitting hole formed in the central region of the flat abutment surface that has been machined into a bare piece, and the positioned input shaft of the coaxial reduction gear and the motor output shaft of the drive motor are coaxially coupled. A joint structure of an industrial robot characterized by being configured.