JP2841060B2 - Industrial Robot Joint Device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] The present invention relates to a joint for an industrial robot.
Prevent the generation of resonance vibrations of devices, especially robot arms
About things. [0002] 2. Description of the Related Art In general, in industrial robots,
To obtain an output torque suitable for
High-speed, low-torque electric servomotor or electric
A pulse motor and a converter that converts this output to low speed and high torque.
Speed device. Also, such a reduction gear
For example, it has a large reduction ratio of about 1/120.
That the backlash between the gears, ie the so-called back
Small rush and low inertia
It is required to be lightweight. [0003] Conventional reduction gears satisfying such demands
For example, Japanese Patent Application Laid-Open No. Sho 59-175986 discloses
Patent application title: Harmonic gear device as shown
Eccentric swing type play as disclosed in JP 06744
There is a star gear device. The former reduction ratio is generally 1/80 to 1
/ 320, and the latter reduction ratio is generally 1/6 to 1
/ 200 or so. In addition, the former has a lower reduction ratio than the latter.
Most robots have small outer diameter and weight
The reduction ratio and the necessary reduction gear for the drive of the joint of the arm
And mechanical strength. Therefore, the robot
Most of the reduction gears for driving the joints of the
Body is applied and, in rare cases,
Which large reduction ratio is required, that is, small capacity and high speed
Rotation (for example, when the output is less than 1000 watts and the number of rotations is 5
000rpm) type motor for driving robot arm
Requires a reduction ratio of about 1/625
For details, see JP-A-56-152594.
Coupled front gearbox to harmonic gear as shown
What was used is used. [0004] However, as described above,
If each of the reduced gears is used for a robot joint device,
Reduction gear in the region where the electric motor speed input to the device is low
Problem that the robot arm and the like cause torsional resonance
was there. The resonance phenomenon involves the joints of the robot arm
In many cases, torsional vibrations appear in the vicinity.
The position of the tip of the arm can no longer be determined.
Tasks such as welding, sealing, and assembly
Work performed in the low speed range of the motor
Problems such as the inability to obtain a work track arise. The reason that resonance occurs
The reason is that each of the above reduction gears, which is the torque transmission mechanism of the electric motor,
Drive system including such a reduction gear due to low rigidity
(Consists of electric motor, reduction gear and robot arm
The natural torsional frequency f of the system₀Is lower and
Of the reduction gear that vibrates due to a machining error in gear cutting, etc.
When the dynamic frequency is in the low rotational speed range of the electric motor,
Frequency f₀It was thought to match. To cope with such a problem, Japanese Patent Laid-Open No. Sho 58-2
No. 11881 discloses that the generated vibration is canceled
An electrical control system that changes the speed command signal of the electric motor
Has been proposed. However, such a scheme
The system becomes unstable when the feedback gain is increased
This is especially true for a robot drive system with low rigidity.
Increase the gain to avoid the problem of easy oscillation.
Can not be heard, and therefore has a sufficient vibration canceling effect.
Absent. Also, Japanese Patent Application Laid-Open No.
The speed reducer is driven by the timing belt to which the force is applied,
A system that absorbs vibration with a tilt has been proposed. I
However, in this method, the timing belt is broken.
There is a danger of refusing. Also, Japanese Patent Application Laid-Open No. 59-151
No. 89 discloses that a main shaft of a speed reducer includes a spring and a weight.
A method of attaching a vibration absorber has been proposed. But this
In the above method, the vibration absorber may be damaged by centrifugal force,
You must adjust the weight etc. according to the load of the bot
There is a problem that it does not. Accordingly, the present invention provides a method for generating a large resonance phenomenon.
Motor rotation speed in the desired motor rotation speed range
Shift the robot to draw an accurate trajectory at its tip
When performing tasks that require
Preventing vibrations improves robot workability
As well as improve the durability of the robot
To provide a joint device for industrial robots
You. [0007] Means for Solving the Problems The present inventors have proposed a robot algorithm.
Spring constant and intrinsic screw of the reduction gear used for the joint device of the arm
Various relations between vibration frequency, torque fluctuation, etc. and resonance phenomena
Researched. First, reducer with high rotation spring constant
By using it for a bot arm joint device,
Drive system natural torsional frequency f₀Can be removed from the practical range
Trial calculations were made as to whether this was possible. But the rotation of the reduction gear
Spring constant K₁(See Fig. 9)
Rotational spring constant K of arm itself₂1/10 to 1/5 of
Therefore, the spring constant of the entire drive system K = K₁・ K₂/ (K₁
+ K₂) Cannot be made very large, and as a result,
Torsional frequency f₀= 1/2 · π · (K / J)
^1/2(Where J is the moment of inertia of the drive train)
I can't make it big. Therefore, the spring constant K of the reduction gear₁To
By increasing the stiffness,
Natural torsional frequency f of dynamic system₀Out of the practical range
We have come to the conclusion that it is possible. Therefore, the inventors have found that the cause of the vibration is
To reduce the torque fluctuation of the reduction gear. concrete
Use an eccentric oscillating planetary gear reducer to reduce torque fluctuations.
Internal gear and external gear of this reduction gear so as to prevent or reduce
High-precision finishing of gear teeth and torque
The bearing of the eccentric input shaft is designed to absorb any movement
And an annular groove in the shaft support portion of the torque take-out pin, etc.
Was fitted with a rubber ring. However, such a pair
Even if measures are taken, resonance in the practical range cannot be prevented.
The electric motor speed when resonance occurs
Is almost the same as without any countermeasures.
Was. [0009] From the above experimental results, it is possible to reduce a certain mechanism.
If it is a speed device, almost constant torque fluctuation characteristics, that is,
It has vibration frequency characteristics for the drive system of the robot.
A conclusion was drawn. Also, from such conclusions, the robot drive
By changing the mechanism of the reduction gear incorporated in the system, the torque
Hypothesis that the fluctuation characteristics can be outside the practical range.
Various experiments were performed. Content and results of these experiments
Is described later, but from these experimental results the hypothesis is
The following conclusions have been reached. [0010] A structure that could not be considered at all with conventional common sense
In other words, the eccentric oscillating type planetary gear reducer has internal teeth.
The difference in the number of teeth between the wheel and the external gear is 1
The reduction ratio can be about 0, but this reduction ratio can be reduced
And the pre-stage reduction gear having a predetermined range of reduction ratio
Are provided to configure the gear device, which is
The resonance phenomenon
It is possible to deviate from the practical range of the electric motor. Note that the eccentric oscillating type planetary gear reducer has a front stage.
A reduction gear provided with a reduction gear is disclosed in U.S. Pat. No. 4,348,348.
No. 918, disclosed in US Pat.
It is used in traveling equipment and the like. However, like that
The weight of the reduction gear and the backlash
It is not necessary to consider the problems such as queues. Therefore, simply
To easily change the total reduction ratio of the reduction gear
Has a front-stage reduction gear to simply output large torque at low speed.
It's not. On the other hand, high speed, position accuracy, etc.
Required robots with low overall structure rigidity
Reduce the reduction gear weight and backlash.
Is important, the weight at the joint
Eccentric oscillating planetary gear reducer larger than harmonic gear
Elements used, further increasing weight and backlash
It is conventionally thought that providing a pre-stage reduction gear
It was not done. [0012] As a result of further studies by the inventors,
The present invention has been achieved having the following structure. The product according to the present invention
The first part of the joint device of the industrial robot is the first part.
Material and a second part rotatably supported by the distal end of the first member
Materials and1st memberAn electric motor arranged at the tip of theNo.
One memberAt the end of the motor to reduce the speed of the electric motor
And a reduction gear for transmitting the rotation to the second member.
Industrial robot joint device A. The speed reducer (1) A pre-stage reduction gear for reducing the rotation speed of the electric motor
When, (2) A post-stage speed reducer that reduces the output speed of the front-stage speed reducer
And having(3) The reduction ratio of the front reduction gear and the reduction ratio of the rear reduction gear
The total reduction ratio of the speed reducer is given by the reduction ratio.
The ratio is set within the range of the actual reduction ratio of the planetary gear unit alone.
And B. The preceding reduction gear is (1) Fit to output rotating shaft of electric motorSleeve partWhen
Such as an input gear integrally provided at the tip of the sleeve
Input rotation axis consisting of (2) a plurality of output gears meshing with the input gear;
Consisting of a parallel shaft type gear device, C. The latter reduction gear (1) Crank shafts respectively coupled to the output gear
When, (2) Eccentric swinging by engaging with each crankshaft
An external gear having a through hole in the part, (3) With an internal gear that meshes with the external gear
A cylindrical body attached to the first member; (4) Each crankshaft is rotatably supported via a bearing.
With a central hole in the center and attachment to the second member
An eccentric oscillating type planetary gear train having a support having an end face
Consists of D. The rotation axis of the electric motor and the eccentric oscillating gear device
Align the rotation axis of the cylinder or supportOn the same axisArranged in E. FIG. The input gear and output gear are more
Closer to the electric motor than the mounting end face of the support
And F. (1) Three outer diameters of the input gear of the input rotary shaft
The outer diameter of the eccentric oscillating type planetary gear device.
The inner diameter of the center hole of the support is larger than the outer diameter of the sleeve.
hand, (2) The sleeve of the input rotary shaft on the output rotary shaft of the electric motor
The part is fitted and fixed with a fastening member, (3) The input gear is output through the through-hole of the external gear.
While engaging with the car, the tip of the sleeve part is a cylinder
Through the electric motor side end face and inserted into the center hole of the support.
It is characterized by having been done. Invention of claim 2
The joint device for an industrial robot according to claim 1, wherein the joint device is an industrial robot.
In the joint device of the robot, the mounting end face of the support is located at the front.
Positioned on the anti-electric motor side from the anti-electric motor side end surface of the cylinder
It is characterized by doing. Claim3Stated
The joint device for an industrial robot according to the invention is described in claim1Stated
Among the joint devices of industrial robots, the speed reduction of the preceding reduction gear
The ratio is 1/2 to 1/5, and the post-stage reduction ratio is 1/25 to 1 /
By setting each within the range of 60, the total reduction
It is characterized by satisfying the speed ratio.
You. And according to the present invention, I. Especially for industrial robots, weight and cumulative backlash
It is required to improve the control performance by reducing the
In contrast, single idlers such as harmonic gears
In order to satisfy the required reduction ratio by the star gear device,
In the joint device of an industrial robot that can constitute a reduction gear unit
The reduction gear unit to an eccentric oscillating planetary gear unit
On the input side of the high-speed gearbox
) And the necessary reduction by the front reduction gear and the rear reduction gear
Because the speed ratio is obtained, resonance occurs in the robot.
Even if the electric motor
The number of turns can be shifted to the desired motor speed range.
it can. As a result, the robot receives its tip (tool
And other tasks that require drawing accurate trajectories.
Can prevent the occurrence of large vibrations when
In addition to improving the workability of the robot,
Durability can be improved. B. Also, the input shaft member is connected to the output rotation shaft of the electric motor.
The electric motor is connected to the first member (or
Section) to easily configure the pre-stage reduction gear.
can do. As a result, the joint device of an industrial robot
Can be easily assembled and maintained
Performance can also be improved. In addition, the input gear
Provided on the input shaft member separate from the output rotation shaft of the electric motor
Therefore, a commercially available electric motor can be used,
The reduction ratio of the preceding reduction gear can be easily set. C. Furthermore, it is integrated with the tip of the sleeve part of the input rotary shaft.
An input gear is provided, and the input rotary shaft is connected to the output rotary shaft of the electric motor.
The sleeve part is fitted and fixed with a fastening member.
Backlash between the electric motor and the input gear.
You can comb. As a result, robot positioning accuracy
Can be improved. D. Furthermore, slide the outer diameter of the input gear part of the input rotary shaft.
Smaller than the outer diameter of the gear section, the center hole of the support of the planetary gear set
With the inside diameter larger than the outside diameter of the sleeve, set the input gear to planet
Mesh with the output gear through the through hole of the external gear of the gear unit
So that the tip of the sleeve is the cylindrical body of the planetary gear set.
Through the electric motor side end face and inserted into the center hole of the support.
The installation length in the rotation axis direction is shortened.
Can be reduced. As a result, the protrusion of the electric motor
And make the industrial robot more compact.
And reduce interference from the protrusion of the electric motor.
The working range of the robot
Can be wider. In addition, as a reduction gear
Even if there are multiple outputs, the input gear
The load balance of meshing with the power gear is improved,
As a result, the load acts evenly on multiple bearings for supporting the crankshaft.
However, it is possible to prevent a reduction in the life of the reduction gear transmission. [0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An industrial robot according to the present invention will be described below.
Will be described with reference to the drawings. [0014] Embodiment 1 FIGS. 1 to 3 are views for explaining the present invention.
FIG. First, the configuration will be described. FIG.
Is a robot using the joint device of the industrial robot according to the present invention.
FIG. 1 is an electric motor
The flange 2 of the electric motor 1 is attached to the cylinder 4 of the reduction gear 3.
Fixed. The cylindrical body 4 is a first arm as a first member
5 is fixed to the tip 5a. Exit of electric motor 1
The power rotation shaft 7 is connected to the input rotation shaft 8 of the reduction gear 3, and is reduced.
The output of the speed change device 3 is transmitted to a shaft 10, and the shaft 10 is
1 and is fixed to a second arm 12 as a second member.
Have been. The cylindrical body 13 at the end of the second arm 12 and the first arm
Cylindrical 5 projecting downward from the lower surface of the tip 5a of the
A pair of bearings 16 are interposed between the protruding body 15.
The speed reducer 3 reduces the rotation speed of the electric motor 1 and
The driven part of the unit, that is, the second arm 12 is rotated.
In addition, the electric motor 1, the reduction gear 3, the second arm 12,
And the load connected to the second arm constitutes a drive system. The speed reducer 3 is shown in FIGS.
A first-stage speed reducer 20 for reducing the number of revolutions of the electric motor 1
Is connected to the pre-stage speed reducer 20 to further reduce the rotational speed.
And a second-stage speed reducer 21. Front reduction gear
Reference numeral 20 denotes a parallel shaft type gear device. Rear reduction gear 21 is fixed
Internal gear 28 and external teeth meshing with the internal gear 28
Swing the external gear 29 by engaging with the wheel 29 and the external gear 29
A crankshaft 30 as an eccentric input shaft to be rotated.
Eccentric oscillating type planetary gear set
You. The internal gear 28 is a pin gear using the pin teeth 31.
And, for example, only one from the number of teeth of the external gear 29
Has a large number of teeth. In addition, the former-stage speed reducer 20 is a normal
It is a parallel shaft type reduction gear and is constituted by a spur gear. The reduction ratio i of the pre-stage reduction gear 20₁And rear reducer
Reduction ratio i of 21₂Is the normal control speed of the electric motor 1
(During normal operation of the robot, for example,
When performing welding work, within the range of (motor rotation speed)
Robot, that is, first arm 5 and second arm 12
And so that resonance with the rear reduction gear 21 does not occur.
I have. Normal control speed of electric motor 1 or robot
Area that requires accurate work trajectory (for performing welding work, etc.)
In the work area), the maximum rotation speed per second
Multiplied by the reduction ratio of the pre-stage reduction gear 20 (the value
Torque fluctuation times per one rotation of the crankshaft 30 described later
Electric motor 1, deceleration)
The device 3, the second arm 12 and the second arm 12
Torsional oscillation frequency (fixed
Torsional frequency f₀Refers to nearby frequencies. Hereinafter the same)
The reduction ratio i of the pre-stage reduction gear 20₁Select
You. In this embodiment, the normal control circuit of the electric motor 1 is used.
The number of turns is 0 to 1000 rpm, and the reduction ratio i of the pre-stage reduction gear 20
₁Is 1/3 and the reduction ratio i of the rear reduction gear 21₂Is 1/4
0, and the overall reduction ratio i of the reduction gear 3 is 1/120.
Has been chosen to be. Natural torsional vibration of the drive system
Number f₀Is the rotation of the electric motor 1 at the resonance peak point.
Number, reduction ratio i of the pre-stage reduction gear 20₁And gearbox 3
This can be calculated backward from the torque fluctuation characteristics described later.
Is about 8.4 Hz. The reduction ratio i of the pre-stage reduction gear 20₁Is less than 1/5
(Meaning that the denominator increases. The same applies hereinafter) or
Reduction ratio i of rear reduction gear 21₂Exceeds 1/25 (denominator
Means smaller. The same applies below)
1/12 using a parallel shaft reducer with a simple structure
Since it is difficult to obtain a total reduction ratio i of 0,
Disadvantageously. Also, the reduction ratio i of the rear reduction gear 21₂
Is less than 1/60 or the reduction ratio i of the pre-stage reducer 20₁Is 1
/ 2 to obtain a total reduction ratio i of 1/120,
In the practical range of the dynamic motor 1, the
The rotational speed is the natural torsional frequency f of the drive system₀(8.
4Hz) Near or higher, preventing resonance
The range that can be made is narrowed. Next, the operation will be described. Electric motor
When 1 is rotated at a normal rotation speed of 0 to 1000 rpm,
Reduction ratio i₁Is 1/3, the output speed of the pre-stage reduction gear 20 is 0
~ 333 rpm, and the reduction ratio i₂Decreased by 1/40
The output rotation speed of the speed changer 21 is 0 to 8.3 rpm.
No large vibration occurs in the range. Output times of electric motor 1
The number of rotations is around 1500 rpm (at this time,
Output speed is 1500 rpm × １ ／ = 500 rpm
In the vicinity, the output rotation speed of the rear reduction gear 21 is 1500 rpm ×
1/3 × 1/40 = 12.5 rpm).
The biggest vibration at the time.Thus, the resonance phenomenon
It is not clear why this occurs outside the practical range of
Estimated from the results, the cause of such resonance phenomenon
The torque fluctuation is generated in the rear reduction gear 21 instead of the front reduction gear 20.
The eccentric oscillating gear device as in the embodiment
The input shaft (crankshaft 30) once per rotation (one
Constant number of times), andAdditionVibrating
It is thought. In the case of the harmonic gear unit, it is estimated from the experimental results.
Then, one rotation of the input shaft (wave generator)
2 times (constant number) of torque fluctuations occur.
If a front-stage reduction gear with a reduction ratio of 1/3 is attached to the
750 x 1/3 x 2 = around 750 rpm
500 torque fluctuations per minute occur, causing
Modulus f₀Is 8.4 Hz (500 vibrations /
Per minute), the rotation speed of the electric motor is within the practical range.
It is considered that resonance occurs around 750 rpm.
In this case, when the number of vibrations per minute is approximately 500,
Vibration, the harmonic reduction gear has a reduction ratio i =
By providing a front-stage reduction gear of about 1/6,
The rotational speed of the dynamic motor is set to 1500 rpm, which is out of the practical range.
It is also conceivable to raise it to near the heart. But,
Reduction ratio i of harmonic gear reducer₂Is at leastAbout 1/80
Therefore, the total reduction ratio i is at least 1/480And 1 to
An electric motor with a practical range of 1000 rpm is generally required
Cannot satisfy the reduction ratio i (about 1/120).
Therefore, it will not be practical. The electric motor 1 and the pre-stage reduction gear 20
These vibrations do not affect the oscillation of the drive system.
The vibration is small,
It is considered to be due to absorption. (Experimental example) In addition to the speed reducer of the above embodiment,
Describes vibration measurement tests performed on the reduction gears shown.
I will tell. Eccentric oscillating type of the above embodiment and comparative examples 1 and 2
Planetary gear reducer, swinging of crankshaft and external gear
To reduce the vibration amplitude by preventing imbalance due to
Therefore, similarly to the second and third embodiments described later, the number of external gears is two.
These are assembled with a phase difference of 180 degrees
And the number of teeth of the internal gear is one more than the number of teeth of the external gear
Used was used. Reduction gear of each reduction gear
Number, reduction ratio i₁, I₂, Rotation spring constant K₁(See Fig. 9)
And the moment of inertia J are shown in Table 1 below. [0022] [Table 1] The experiment was conducted according to the overall configuration diagram shown in FIG.
did. That is, the output shaft 51a of the electric servomotor 51
A reduction gear 52 is attached to the output shaft 52 of the reduction gear 52.
a shows the moment of inertia of the driven part (second arm) of the robot
Flywheel 53 as an inertial load equivalent to
Was attached. Radius of flywheel side 53a
A piezoelectric element that can measure the acceleration and amplitude in the circumferential direction
An acceleration pickup 54 using a child was attached. This
The output of the acceleration pickup 54 is
Are linked. The motor 51, the reduction gear 52, and the
Natural frequency f of the drive system composed of the wheel 53₀Is about
It is adjusted to 8.4 Hz. Electric motor rotation
Change the number to increase the flywheel acceleration at that time.
The size was measured. FIG. 4 shows the measurement results. The horizontal axis is electric
The vertical axis indicates the number of rotations of
The circumferential acceleration (unit: G) detected at step 54
Show. In Comparative Examples 1, 2 and 3
Therefore, the resonance peaks are
The number is approximately 750 rpm, approximately 500 rpm and approximately 250
rpm, the normal control speed of the electric motor 51
The largest vibration occurs in the range of 0 to 1000 rpm
You. However, implementation using the speed reducer according to the present invention
In the case of the example, 1500r which is out of the practical range of the electric motor
pm, a resonance peak occurs near the center.
Movement is the largest. Examples, Comparative Examples 1 and Comparative Examples
2, the number of rotations of the electric motor 51 at the time of resonance
Is inversely proportional to the reduction ratio i1 of the preceding reduction gear.
Can be The embodiment of the present invention is shown in FIGS.
7 will be described. In the above brief description,
In the same configuration as in FIGS. 2 and 3 used, the same reference numerals are used.
Will be described. In FIGS. 6 and 7, reference numeral 40 indicates the position shown in FIG.
A reduction gear driven by the electric motor 1
The speed device 40 is connected to the output rotary shaft 7 of the electric motor output 1.
Parallel shaft type pre-stage reducer 20 and this pre-stage reducer 20
And a planetary gear train 21 connected to the rear stage.
ing. The tip 7a of the rotating shaft 7 of the electric motor 1 is
It has a screw 7b at the tip. To the screw part 7b
Is a connecting shaft 7c which forms a part of the output rotary shaft of the electric motor.
Is screwed. Reference numeral 8 denotes an input rotation shaft, and a tip 8a
Is provided with a pinion 22 which is an input gear of the pre-stage reduction gear 20.
And the output rotary shaft 7 of the electric motor is penetrated.
It has a hole 8b, and the hole 8b engages with the tapered portion of the rotating shaft 7.
It has a tapered hole portion. This tapered hole of the input rotary shaft 8
Part is a sleeve part that fits on the output rotary shaft of the electric motor.
Constitute. The input rotary shaft 8 is the output rotary shaft 7 of the electric motor 1.
Is screwed by a nut 23 to the tip 7a of
The tip 7a of the rotating shaft 7 is connected to the input rotating shaft 8 by the half moon key 24.
More fixed. With this configuration, the input rotary shaft
8 has a smaller diameter than the shaft diameter of the motor rotating shaft 7.
Therefore, the number of teeth of the pinion 22 is
Compared to the case where the number of teeth is directly mounted on the motor
Commercially available with a large rotating shaft diameter for its capacity
Even if the electric motor 1 is used, a predetermined pre-stage deceleration
Ratio can be obtained. Three of the meshes with the pinion 22
The spur gear 25 is respectively connected to three crankshafts 30 described later.
Are connected. The planetary gear reducer 21 is fixedly mounted on the cylinder 4.
A pair of internal gears 28 engaged with the internal gear 28
Of the external gear 29 and the external gear 2
3 cranks as eccentric input shafts for oscillating rotation of 9
And a shaft 30. Also, the internal gear 28
It is composed of a pin gear using the pin teeth 31, for example, external teeth
The number of teeth is one more than the number of teeth of the gear 29. 3
Reference numeral 3 denotes a disk part, and the disk part 33 is a part of the planetary gear reducer 21.
Constitutes a front end and equally distributes the crankshaft 30 on the circumference
It is pivotally supported via a bearing 34. 35 is a block
The block body 35 has an axial circle at its center.
Cylindrical hole36bAnd the input rotary shaft 8 is loosely fitted.
Similarly, holes are formed in the center portions of the external gear 29 and the disk portion 33.2
9a and hole 36aIs provided. Block 35
Is recessed at the rear end 35a36cAnd the shaft 10
Face 39. Dent36cAnd flange part 3
9, a pre-stage reduction gear 20 is provided in the cavity formed by
It is stored. The crankshaft 30 is attached to the block body 35.
They are equally arranged on the circumference and are supported via bearings 41.
The extension 30a of the crankshaft 30 is recessed36cProtruding into
And is fixed to a spur gear 25. The crankshaft 30 includes a disk 33 and a block.
35, and the center of the crankshaft 30 is
It has a pair of crank portions 42 having a phase difference of 80 degrees,
The crank part 42 is connected to the external gear 29 via a bearing 43.
Is eccentrically swung. Here, the aforementioned circle
The plate part 33 and the block body 35 constitute a support body 44.
You. Disk part 33, block body 35 and flange part 39
Are mutually connected by a plurality of bolts 46 and fixing nuts 47.
Fixed.Disc-shaped hole 36a and block
The cylindrical hole 36b of the body 35 forms the central hole 36 of the support 44.
To achieve. Three outer diameters of the input gear portion 22 of the input rotary shaft 8
Of the eccentric oscillating type planetary gear device
The inner diameter of the center hole 36 of the support is determined by the outer diameter of the sleeve 8c.
I am large. Input rotary shaft to output rotary shaft 7 of electric motor
8 as a fastening member.
-24. Input gear 22 is external gear 2
9 meshes with the output gear 25 through the through hole 29a.
At the same time, the tip of the sleeve portion 8c is
Pass through the end face 4a on the side of the
Have been. The rotation of the electric motor 1 is controlled by the output rotation shaft 7 and
Transmission to the pinion of the pre-stage reduction gear 20 via the input rotary shaft 8
The speed is reduced by the pre-stage reduction gear 20. Of the pre-stage reducer 20
The output is the clutch of the eccentric oscillating star gear device 21 by the spur gear 25.
It is input to the link shaft 30. Next, the crankshaft 30 is turned.
An external gear 29 that is eccentrically swung by rolling, and the external gear
Has one more tooth than external gear 29 meshing with gear 29
The external gear 2 is further decelerated by the internal gear 28
The slow rotation of Ninth 9 is a support that acts as a carrier.
The arm 12 is rotated by being transmitted from the holding body 44 to the shaft 10 and rotated.
You. ElectricThe flange portion 2 of the dynamic motor 1 includes a planetary gear reducer 2
The first cylindrical body 4 is coupled to an end surface 4a on the electric motor 1 side.
You. The rotation axis of the rotation shaft 7 of the electric motor 1 and the eccentric oscillating teeth
The rotation axis of the cylinder 4 or the support 44 of the vehicle
They are arranged on one axis. Input gear 22 and output gear 2
5 on the side opposite to the electric motor with respect to the external gear 29,
Are disposed closer to the electric motor than the mounting end surface 35b.
The mounting end surface 35b of the support is the end surface of the cylinder 4 on the side opposite to the electric motor.
4b is located on the side opposite to the electric motor. In the present embodiment, the electric motor 1
The control rotation speed is (0 to 1000 rpm,
Reduction ratio i₁Is 1/3, the reduction ratio i of the planetary gear reducer 21₂
Is 1/40, the total reduction ratio i of the reduction gear 3 is 1/120,
Including the dynamic motor 1, the reduction gear 3, and the second arm 12
The natural torsional frequency f of the configured drive train₀Is about 8.4H
z. Therefore, the electric motor 1 is
The rotation speed (8.4H) corresponding to the natural torsional frequency of the drive system
500 rpm corresponding to z) in the normal control range (0 to 100).
0 rpm). In addition, the former-stage speed reducer 20
The maximum number of revolutions per second in the normal control range of the dynamic motor 1 (10
16.7 revolutions per second, equivalent to 00 rpm)
Natural torsional frequency f₀(5.6 times per second
Speed reduction ratio i₁(１ ／). Decrease
Spring constant K of speed changer 40₁Is about 37.5kgm / min
It is. The operation and vibration characteristics in the case of this embodiment are as described above.
This is the same as the first embodiment described above. In the present invention, the reduction of the speed of the preceding stage
The speed ratio is the maximum number of revolutions per second of the electric motor, the resonance phenomenon
The frequency at which the vibration starts to occur
Frequency)), that is, slightly higher than the natural frequency of the drive system.
Any value may be used as long as the value decelerates to a value corresponding to a small frequency. For example
Drive system natural torsional frequency f₀Is 5-9Hz
Therefore, the maximum rotation speed of the electric motor is 1000 rpm,
When the speed ratio i is 1/60 to 1/320, the preceding stage minimum reduction ratio
i₁From about 1 / 1.9 to about 1/6, the reduction ratio i at the subsequent stage₂1
/ 25 to 1/60 to control resonance in the practical range
Can be removed. Also, the natural torsional frequency f of the drive system
₀Is 5 to 9 Hz, and the rotation speed of the electric motor is
Maximum 2000 rpm, total reduction ratio i is 1/110 to 1/3
In the case of 20, the preceding stage minimum reduction ratio i₁From about 1 / 3.7 to about
1 / 6.7, rear-stage reduction ratio i₂From about 1/25 to about 1/60
Robot joints that do not cause resonance
Get the position. Similarly (f₀= 5-9Hz)
Dynamic motor rotation speed up to 4000 rpm, total reduction ratio i is 1
/ 210 to 1/640, the preceding stage minimum reduction ratio i,
About 1 / 7.4 to about 1 / 13.3, rear-stage reduction ratio i₂About 1
/ 30 to about 1/60. In addition, the drive system
Torsional frequency f₀Is 10 to 15 Hz,
The maximum rotation speed of the dynamic motor is 1000 rpm, and the total reduction ratio i is
1/80 to 1 /240In the case of, the preceding stage minimum reduction ratio i₁1
/1.5 to 1/4, reduction ratio i at the subsequent stage₂From 1/25 to 1 /
By setting it to 60, the resonance phenomenon can be removed from the practical range.
it can. Similarly (f₀= 10 to 15 Hz)
The maximum rotation speed of the electric motor is 4000 rpm, total deceleration
When the ratio i is 1/125 to 1/600, the pre-stage reduction ratio i
₁From about 1 / 4.5 to about 1/10, and the reduction ratio i₂About
It may be 1/30 to 1/100. [0032] Advantages of the invention According to the invention, especially industrial robots
Control by reducing weight and cumulative backlash
While it is required to improve performance,
Required by a single planetary gear set, such as a harmonic gear set
The speed reducer can be configured to satisfy
In the joint device of an industrial robot,
On the input side of the eccentric oscillating planetary gear unit (rear-stage reduction gear)
A parallel shaft type gear unit (pre-stage reduction gear) is provided to reduce the pre-stage
To obtain the required reduction ratio by using the
Therefore, even if resonance occurs in the robot,
The motor rotation speed at the time of vibration
It can be shifted to the rotation speed range. As a result,
Draw an accurate trajectory on the bot with its tip (tool gripping, etc.)
Large vibrations when performing tasks that require
Can prevent the robot from working.
As well as improve the durability of the robot
it can. B. Also, the input shaft member is connected to the output rotation shaft of the electric motor.
The electric motor is connected to the first member (or
Section) to easily configure the pre-stage reduction gear.
can do. As a result, the joint device of an industrial robot
Can be easily assembled and maintained
Performance can also be improved. In addition, the input gear
Provided on the input shaft member separate from the output rotation shaft of the electric motor
Therefore, a commercially available electric motor can be used,
The reduction ratio of the preceding reduction gear can be easily set. C. Furthermore, it is integrated with the tip of the sleeve part of the input rotary shaft.
An input gear is provided, and the input rotary shaft is connected to the output rotary shaft of the electric motor.
The sleeve part is fitted and fixed with a fastening member.
Backlash between the electric motor and the input gear.
You can comb. As a result, robot positioning accuracy
Can be improved. D. Furthermore, slide the outer diameter of the input gear part of the input rotary shaft.
Smaller than the outer diameter of the gear section, the center hole of the support of the planetary gear set
With the inside diameter larger than the outside diameter of the sleeve, set the input gear to planet
Mesh with the output gear through the through hole of the external gear of the gear unit
So that the tip of the sleeve is the cylindrical body of the planetary gear set.
Through the electric motor side end face and inserted into the center hole of the support.
The installation length in the rotation axis direction is shortened.
Can be reduced. As a result, the protrusion of the electric motor
And make the industrial robot more compact.
And reduce interference from the protrusion of the electric motor.
The working range of the robot
Can be wider. In addition, as a reduction gear
Even if there are multiple outputs, the input gear
The load balance of meshing with the power gear is improved,
As a result, the load acts evenly on multiple bearings for supporting the crankshaft.
However, it is possible to prevent a reduction in the life of the reduction gear transmission.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an overall schematic explanatory view of a joint device of an industrial robot for explaining the present invention. FIG. 2 is a partial cross-sectional view of the reduction gear transmission of FIG. FIG. 3 is a sectional view taken on line AA of FIG. 2; FIG. 4 is a diagram illustrating the performance of the present invention and a comparative example. FIG. 5 is an overall configuration diagram of an experimental example according to FIG. 4; FIG. 6 is a sectional view of a main part of the embodiment. FIG. 7 is a sectional view taken along the line BB of FIG. 6; [Description of Signs] 1 Electric motors 3, 40 Reduction gear 5 First member 12 Second member 20 Front reduction gear 21 Rear reduction gear 28 Internal gear 29 External gear 30 Crankshaft

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B25J 17/00 F16H 1/32

Claims (1)

(57) [Claims] A first member, a second member rotatably supported by the distal end of the first member , an electric motor disposed at the distal end of the first member , and an electric motor rotating at the distal end of the first member. A speed reducer for reducing the number of rotations and transmitting the rotation to the second member. A front reduction gear for decelerating the rotation speed of the reduction device (1) the electric motor, (2) and the rear speed reducer for reducing the output speed of the front stage speed reducer has a (3) the front reduction gear Reduction ratio of the rear reduction gear
The total reduction ratio of the speed reducer is given by the reduction ratio.
The ratio is set within the range of the actual reduction ratio of the planetary gear unit alone.
It is, B. (1) an input rotary shaft including a sleeve portion fitted to an output rotary shaft of the electric motor and an input gear integrally provided at a tip of the sleeve portion; B. a plurality of output gears meshing with each other, and a parallel shaft type gear device having: (2) an external gear having a through hole in the center thereof, (1) a crankshaft which is respectively coupled to the output gear, and (2) an eccentrically oscillating engagement with each crankshaft. 3) a cylinder having an internal gear engaged with the external gear and attached to the first member; and (4) a rotatable support of each crankshaft via a bearing, a central hole in the center, and C. a support having an end face attached to the second member, and an eccentric oscillating type planetary gear device having: B. disposing the rotation axis of the electric motor and the rotation axis of the cylinder or the support of the eccentric oscillating gear device on the same axis ; B. the input gear and the output gear are arranged closer to the electric motor than the external gear and closer to the electric motor than the mounting end face of the support; (1) The outer diameter of the input gear portion of the input rotary shaft is smaller than the outer diameter of the sleeve portion, and the inner diameter of the center hole of the support of the eccentric oscillating planetary gear device is larger than the outer diameter of the sleeve portion. (2) The sleeve portion of the input rotary shaft is fitted to the output rotary shaft of the electric motor and fixed with a fastening member. (3) The input gear meshes with the output gear through the through hole of the external gear, and the sleeve is The distal end of the portion passes through the end face on the electric motor side of the cylindrical body, and is inserted into the central hole of the support. 2. The joint device for an industrial robot according to claim 1, wherein a mounting end surface of the support is located closer to the anti-electric motor side than an end surface of the cylindrical body opposite to the electric motor. 3. The total reduction ratio is satisfied by setting the reduction ratio of the front reduction gear in the range of 1/2 to 1/5 and the rear reduction ratio in the range of 1/25 to 1/60, respectively. The joint device for an industrial robot according to claim 1, wherein: