JPH0957667A - Motor structure and driving device of uniaxial robot - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve even maintenance performance while attaining an improvement in controllability and size reduction in the constitution of a driving structure having a motor and a shaft to be rotated. SOLUTION: A shaft 5 to form a rotor shaft of a motor 1 is housed in a motor main body 5, and a cylinder part 12 which extends in the shaft direction and is formed to install a shaft to be rotated opening on the output side of the motor 1, is formed in this shaft 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor structure and a drive device for a single-axis robot using a motor to which the motor structure is applied as a drive source.

[0002]

2. Description of the Related Art Conventionally, there is generally known a motor having a main body having a rotor and a stator incorporated therein, and a shaft constituting a rotor shaft protruding from the main body.

The frequency of use of such a motor is extremely high, and it is widely used in various fields of industry. For example,
In an industrial single-axis robot, a ball screw is connected to the motor, and the ball screw is rotationally driven by the motor to linearly move a work member or the like attached to a nut portion of the ball screw via a bracket. I am trying to move it.

In the above-described single-axis robot, it is general that the ball screw shaft constituting the ball screw and the output shaft of the motor are connected via a coupling. However, in recent years, for the purpose of improving the controllability of the ball screw drive and downsizing the single-axis robot, the shaft forming the rotor shaft of the motor is extended by a predetermined length and the extended portion of the shaft is screwed. By screwing
The rotor shaft of the motor and the ball screw shaft of the ball screw are integrated, and the applicant of the present application has also developed and applied for a ball screw driving device adopting such a structure (Japanese Patent Application Hira 6-313642).

[0005]

However, in the above-described ball screw driving device, since the rotor shaft of the motor and the ball screw shaft are integrated, for example, the ball screw shaft is not damaged. Even if it occurs, or if the motor body fails and needs to be replaced, the entire motor including the ball screw is required to be replaced. It is impossible to replace only.

Further, in this type of single-axis robot, normally,
As a position detecting means, a rotary encoder is provided on a shaft that constitutes a rotor shaft, and the rotary encoder is integrally incorporated in a motor. When replacing such an encoder, the entire motor including the ball screw is replaced in the same manner as above. There is a need.

However, in order to replace the entire motor including the ball screw, almost the entire single-axis robot must be disassembled and replaced, which results in poor workability during maintenance.

The present invention has been made to solve the above-mentioned problems, and in the structure of the drive structure including the motor and the rotated shaft, the controllability is improved and the size is reduced, while maintaining the maintainability. An object of the present invention is to provide a motor structure and a single-axis robot drive device that can be improved.

[0009]

According to another aspect of the present invention, there is provided a motor structure in which a shaft constituting a rotor shaft of a motor is housed in a motor main body, and the shaft extends in the axial direction of the shaft and at least an output side of the motor. Is formed by forming a cylindrical portion for mounting the rotating shaft, which is open at the end face.

According to this motor structure, the rotating shaft and the motor are connected in a state where the rotating shaft is inserted in the tubular portion of the shaft forming the rotor shaft, so that coupling is performed in the connection between the rotating shaft and the motor. Can be omitted, and moreover, since the rotated shaft is connected while being inserted in the motor, in the drive structure using the rotated shaft and the motor,
It is possible to shorten the space in the direction of the rotated shaft.
Further, since the coupling is not required, there is no interposition of a portion having low torsional rigidity between the rotated shaft and the rotor shaft, and the amount of rotation between the rotor shaft and the rotated shaft is reduced. The deviation is prevented and the controllability is improved. Further, since the rotated shaft and the motor can be separated, it is possible to replace the motor or the rotated shaft alone in the drive structure using the rotated shaft and the motor, which improves maintainability.

According to a second aspect of the present invention, there is provided the motor structure according to the first aspect, wherein the output side end of the shaft is supported via an angular bearing, and the opposite side of the shaft near the end is a bearing. It is supported through.

According to this motor structure, the support rigidity of the rotated shaft when the rotated shaft is attached is increased, and a supporting member such as a bearing for supporting the rotated shaft is provided at the connecting portion between the rotated shaft and the motor. There is no need to provide it separately.

According to a third aspect of the present invention, there is provided the motor structure according to the second aspect, wherein the outer ring portion and the inner ring portion of the angular bearing are axially sandwiched between the motor body and the shaft. It is provided.

According to this motor structure, axial play between the motor body and the shaft is suppressed, and the positional accuracy of the rotated shaft in the axial direction is improved.

A drive device for a single-axis robot according to a fourth aspect is a single-axis robot equipped with the motor having the structure according to any one of the first to third aspects, and linearly along a guide rail. A movable member that moves, a ball screw shaft screwed into a nut portion of the movable member, and the motor as a drive source that rotates the ball screw shaft,
One end side of the ball screw shaft is integrally rotatably coupled to the shaft of the motor in a state of being fitted in the cylindrical portion, and the other end side of the ball screw shaft is rotatably supported by a supporting member of the single-axis robot. It is a thing.

According to such a single-axis robot driving device, a controllability is good and a compact structure is achieved as in the conventional device of this type in which the rotor shaft of the motor and the ball screw are integrated. However, it becomes possible to provide a drive device for a single-axis robot that has better maintainability.

[0017]

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view showing a motor to which a motor structure according to the present invention is applied. Motor 1 shown in this figure
Has a cylindrical casing 2, and a stator 3 including a stator core, a stator winding, and the like is provided in the casing 2.
Further, a rotor 4 having a magnet arranged therein is arranged, and a shaft 5 forming a rotor shaft is arranged at the center of the motor 1, and the rotor 4 is coupled to the shaft 5.

The shaft 5 constituting the rotor shaft is rotatably supported by the casing 2 via bearings. In the illustrated example, the shaft 5 is supported by angular bearings 6 and bearings 7 (hereinafter, simply referred to as bearings 6 and 7) at two locations in the axial direction (the horizontal direction in FIG. 1) with the stator core or the like interposed therebetween. In particular,
A plurality of rows of bearings 6 are provided on the output side (left side in FIG. 1) of the motor 1 to which the shaft to be rotated is coupled, and thereby the support rigidity of the shaft 5 is enhanced.

The output side bearing 6 has a rib 2a formed on the inner peripheral surface of the casing 2 and an annular nut member 8 screwed from the output side of the motor 1 to the inner peripheral surface of the casing 2.
The outer ring portion is clamped by and is held by the casing 2. Also, the bearing 6 is
An inner ring portion is held by a flange 5a formed on the shaft 5 and a nut member 10 screwed to the shaft 5 from the output side of the motor 1, whereby the inner ring portion of the bearing 6 is coupled to the shaft 5. ing. The bearing 7 on the side opposite to the output side is held between the casing 2 and the shaft 5 by a retaining ring or the like.

On the output side end surface of the nut member 10,
As shown in FIG. 2, screw holes 11 are screwed in a plurality of positions in the circumferential direction, and when connecting the rotated shaft to the motor 1,
A stopper plate or the like can be attached using the screw hole 11.

The shaft 5 is dimensioned so that the axial dimension thereof hardly projects from the casing 2. A tubular portion 12 corresponding to the diameter of the rotated shaft is formed inside the shaft 5, and the tubular portion 12 is open to the output side of the motor 1. An encoder 13 as a position detecting means is attached to the end of the shaft 5 on the side opposite to the output side of the motor 1, which is schematically shown.

In FIG. 1, reference numeral 14 is an oil seal for preventing leakage of lubricating oil between the casing 2 and the shaft 5.

Next, the configuration of a single-axis robot as an application example of the motor 1 configured as described above will be described with reference to FIG.

In the figure, the single-axis robot 20 is formed in a frame shape extending in a uniaxial direction from the base member 21, the cover 22, etc., and a ball screw 23 is arranged inside the frame, and at the same time, the above-mentioned motor is used as a drive source. 1 is equipped.

The ball screw 23 is a ball screw shaft 24.
And a nut member 25 screwed onto the ball screw shaft 24 via a ball (not shown). A moving bracket 26 for mounting a working member is fixed to the nut member 25. There is. A guided member (not shown) is provided on the lower surface of the moving bracket 26, and the guided member is provided on the upper surface of the base member 21 and extends in the longitudinal direction of the uniaxial robot 20. It is attached to 27.

The ball screw shaft 24 is arranged in parallel with the guide rail 27, and one end side (left side in FIG. 3) of the ball screw shaft 24 is erected on the base member 21.
8 is rotatably supported by a bearing 29, and the other end side (right side in FIG. 3) is connected to the motor 1.

The motor 1 is mounted on a support block 30 provided upright on the end of the base member 21 opposite to the support block 28, and the ball screw shaft 24 is attached.
The other end side is inserted into the tubular portion 11 of the shaft 5 of the motor 1 through a through hole formed in the support block 30.
Then, a wedge-shaped retaining ring 31 called a span ring is press-fitted into a gap between the inner peripheral surface of the tubular portion 11 and the outer peripheral surface of the shaft 5, and the retaining plate 32 is attached to the nut member 10 to separate the retaining ring 31. Is blocked, the shaft 5
The ball screw shaft 24 and the ball screw shaft 24 are firmly coupled to each other with their axes aligned with each other, whereby the shaft 5 and the ball screw shaft 24 are integrally rotatable.

Next, the function and effect of the single-axis robot 20 will be described.

The ball screw shaft 2 is driven by driving the motor 1.
4 is rotated, the nut member 25
Also, the moving bracket 26 fixed to this moves along the guide rail 27. Then, the encoder 13
The motor 1 is controlled by the control means (not shown) in response to the signal from the control means, and thereby the moving speed and the moving amount of the moving bracket 26 are controlled.

Since the ball screw shaft 24 is directly connected to the shaft 5 serving as the rotor shaft when the single-axis robot 20 is operated in this manner, the rotation amount of the rotor shaft and the rotation amount of the ball screw shaft. Is prevented from occurring, and the motor 1 is accurately controlled based on the output signal from the encoder 13. That is, when the rotor shaft of the motor and the ball screw shaft are connected to each other via a coupling, a portion having low torsional rigidity is interposed between the two shafts, so that the amount of rotation between the two shafts may deviate. However, according to the configuration of the above embodiment, such a situation does not occur, and the motor control can be performed with high accuracy.

Further, as described above, since the ball screw shaft 24 is connected in a state of being inserted inside the motor 1 without using a coupling, the coupling and the coupling are different from the structure using the coupling. The space is shortened in the axial direction of the ball screw shaft 24 by the amount of a supporting member such as a bearing that supports the ball screw at the joint between the ball screw and the ball screw. That is, if the effective range of the ball screw (movable bracket movable range) is made equal, the axial dimension of the single-axis robot can be shortened, and conversely, if the axial dimension of the single-axis robot is made equal, the ball screw It is possible to take a long effective range. Therefore, it is possible to effectively achieve the downsizing of the single-axis robot.

In addition, the single-axis robot 20 of the above embodiment
Then, by removing the retaining ring 31 and the retaining plate 32 for coupling the ball screw shaft 24 and the shaft 5, the ball screw shaft 24 and the motor 1 can be easily separated from each other. If it occurs, or if the ball screw shaft 24 is damaged, the ball screw shaft 24,
Alternatively, the motor 1 can be individually removed and replaced.

Therefore, like the conventional structure in which the rotor shaft of the motor and the ball screw are integrated, almost the entire robot is disassembled and the entire motor including the ball screw is replaced when the ball screw or the motor fails. Without doing so, the cover 22 of the single-axis robot 20 can be removed and only the ball screw shaft 24 or the motor main body can be replaced, which improves the maintainability of the single-axis robot.

The motor 1 described in the above embodiment
Is an example of a motor to which the motor structure according to the present invention is applied, and the specific structure can be appropriately changed without departing from the gist of the present invention. For example, as shown in FIG.
The outer ring portion of the bearing 6 is sandwiched between the rib 2 b formed on the output side of the casing 2 and the bearing 6 and the casing 2
The motor 1 is configured so as to be held by the nut member 35 screwed to the inner peripheral surface of the casing 2 from the inner side of the shaft 2, and to form the screw hole 11 for mounting the rotating shaft on the end surface of the shaft 5. May be. Further, as shown in FIG. 5, the outer ring portion of the bearing 6 is clamped by the same structure as in FIG. 4, while the dimension between the nut member 10 screwed to the shaft 5 and the bearing 6 is set in the axial direction. The motor 1 may be configured so as to hold the inner ring portion of the bearing 6 with the collar 36 having the above.

Further, as shown in FIG. 6, the motor 1 may be constructed so as to have a through hole structure which penetrates the cylindrical portion 12 formed on the shaft 5 in the axial direction of the shaft 5.

When the motor 1 and the rotating shaft are connected in this structure, for example, a screw hole 38a is screwed into the end surface of the rotating shaft 38 and a flange portion 38b is formed in the vicinity of the end portion, and the flange portion 38b is formed. The tip end side portion is inserted into the tubular portion 11, and a wedge-shaped retaining ring 39 such as the above-mentioned span ring is press-fitted into the gap between the inner peripheral surface of the tubular portion 11 and the rotated shaft 38.
Then, in the cylindrical portion 12, the bolt 40 engaging with the opening edge on the side opposite to the insertion side of the rotated shaft 38 is screwed into the screw hole 38b of the rotated shaft 38, and the flange portion 38a outputs the output of the cylindrical portion 12. The rotated shaft 38 may be pulled in and fixed until it engages with the opening edge on the side. According to such a connecting method, the rotated shaft 38 and the shaft 5 can be connected more firmly.

[0038]

As described above, according to the motor structure of the present invention, the rotated shaft and the motor are connected with the rotated shaft being inserted in the tubular portion of the shaft that constitutes the rotor shaft. A coupling can be omitted in the connection between the rotating shaft and the motor, and moreover, since the rotated shaft is connected while being inserted into the motor, in the drive structure using the rotated shaft and the motor, The space in the direction of the rotated axis can be shortened.

Further, since the coupling is unnecessary,
A portion with low torsional rigidity does not exist between the rotated shaft and the rotor shaft, and deviation between the amount of rotation of the rotor shaft and the amount of rotation of the rotated shaft is prevented, so controllability is improved. Is improved.

Further, since the driven shaft and the motor can be separated, it is possible to replace the motor or the driven shaft by itself in the drive structure using the driven shaft and the motor, and maintainability is improved. Is improved.

Therefore, by adopting such a motor structure in the motor constituting the drive unit for the single-axis robot, the controllability is the same as in the conventional device of this type in which the rotor shaft of the motor and the ball screw are integrated. It is possible to provide a drive device for a single-axis robot having good maintenance and compactness while achieving good maintenance.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of a motor structure according to the present invention.

FIG. 2 is a view taken in the direction of arrow A in FIG.

FIG. 3 is a cross-sectional view showing an example in which the motor shown in FIG. 1 is used in a drive device for a single-axis robot.

FIG. 4 is a cross-sectional view showing another example of the motor structure according to the present invention.

FIG. 5 is a cross-sectional view showing another example of the motor structure according to the present invention.

FIG. 6 is a cross-sectional view showing another example of the motor structure according to the present invention.

[Explanation of symbols]

 1 Motor 2 Casing 3 Stator 4 Rotor 5 Shaft 6,7 Bearing 8,10 Nut member 12 Cylindrical part 20 Single axis robot 23 Ball screw 24 Ball screw shaft 25 Nut member

Claims (4)

[Claims] 1. A cylindrical portion for mounting a rotary shaft, which accommodates a shaft constituting a rotor shaft of a motor in a motor main body, and extends in the axial direction of the shaft and which is opened at least on an end surface on the output side of the motor. A motor structure characterized by being formed. 2. The output side end of the shaft is supported via an angular bearing, while the shaft and its vicinity on the opposite side are supported via bearings. Motor structure. 3. The motor structure according to claim 2, wherein members are attached to the motor body and the shaft while the outer ring portion and the inner ring portion of the angular bearing are sandwiched in the axial direction. 4. A single-axis robot equipped with a motor having the motor structure according to any one of claims 1 to 3, wherein the movable member linearly moves along a guide rail, and the movable member. It has a ball screw shaft screwed into the nut portion and the motor as a drive source for rotating the ball screw shaft, and is integrated with the motor shaft with one end side of the ball screw shaft being fitted in the tubular portion. A driving device for a single-axis robot, wherein the driving device is rotatably coupled and the other end of the ball screw shaft is rotatably supported by a supporting member.