JPH0631680A - Industrial robot - Google Patents

Abstract

PURPOSE:To provide an industrial robot having a balance mechanism and a lock mechanism for holding a swivelably provided arm to a stop position thereof. CONSTITUTION:The first arm 4 of a robot main unit 2 is vertically raised and swivelably supported onto a supporting base 8, to support the second arm 9 to an upper end of the arm 4. A balance mechanism 5 is mounted between the supporting base 8 and the first arm 4, to apply pressing force to act of a piston-cylinder mechanism 18, by a pressure of air supplied from an air supply unit 6, and also apply spring tension to act of a spring in a cylinder part, on the first arm 4. The supporting base 8 provides a lock mechanism 41 for locking the arm 4 to its position in the case of generating leakage of air in the balance mechanism 5 or such as in an air pipe.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an industrial robot,
In particular, the present invention relates to an industrial robot having a balance mechanism that holds an oscillating arm at its stop position.

[0002]

2. Description of the Related Art For example, in a multi-joint type industrial robot in which a horizontally extending second arm is swingably supported by an upper end of a first arm standing on a swivel base, the first arm is the first arm. A balance mechanism that imparts to the first arm a force that balances with the gravity moment acting on the first arm so that the first arm is stationary at the rotation position because it tilts due to its own weight and the weight of the second arm. Is provided.

As a conventional balance mechanism, for example, there is a mechanism disclosed in Japanese Utility Model Laid-Open No. 61-124388.
In the mechanism of this publication, a spring composed of a tension coil spring is stretched between a first arm that stands upright on a swivel base and is swingably supported, and a bracket that supports a lower end portion of the first arm. Therefore, as the first arm is tilted, the spring is pulled more and the first arm is held at the rotation position.

Further, as another conventional mechanism, Japanese Patent Laid-Open No.
There is also a mechanism in which a counterbalance (weight) for reducing the gravitational moment of a joint portion that receives the gravity of the arm is provided inside the arm as disclosed in Japanese Patent Laid-Open No. 2-162491.

However, when the arm is held only by the spring force of the spring as in the above-mentioned conventional technique, the spring must be made stronger in order to reduce the operating force during the direct teaching operation, and the balance mechanism becomes large. Will end up. In addition, the arm can rotate greatly from the vertical state in the horizontal direction, but there is a limit to the expansion and contraction of the spring,
It is difficult to cover the entire range with only the spring. For example, if the spring constant of the spring is set so as to balance in a state where the arm largely rotates in the horizontal direction,
As the arm approaches vertical, the spring force becomes smaller than the gravitational moment acting on the arm, and it is difficult for the arm to stand still.

Further, in the other conventional case, the weight of the arm itself is increased by providing the counter balance to the arm, and the inertial force when the arm is rotated becomes larger, so that the operating characteristic of the robot is deteriorated. Not only that, a larger driving force is required, so that the motor becomes larger.

[0007]

Therefore, the applicant of the present invention provides a piston-cylinder mechanism having a built-in spring between the arm and the swivel base, and uses the biasing force of the spring and the air pressure of the piston-cylinder mechanism to move the arm. An industrial robot configured to hold is being developed.

In such an industrial robot, the solenoid valve provided in the middle of the air pipe to which the compressed air is supplied is opened to supply the compressed air to the piston-cylinder mechanism to hold the arm. When the arm is stopped, the solenoid valve is closed to switch the piston-cylinder mechanism to the locked state, so that the arm tip can be prevented from dropping by its own weight.

However, in the lock mechanism of the air cylinder, when air leakage occurs, the arm that is stationary in a tilted state cannot be held at that position, and the arm may rotate downward during teaching, for example. Alternatively, the tip of the arm may collide with the floor when the robot is stopped.

Therefore, an object of the present invention is to provide an industrial robot that solves the above problems.

[0011]

The invention according to claim 1 is
An arm swingably supported, one end of which is connected to the arm, and the other end of which is connected to a support portion which supports the arm,
It is characterized by comprising a balance mechanism for keeping the arm stationary at its swing position by air pressure, and a lock mechanism for locking the arm in a swing-disabled state when an air leak occurs in the balance mechanism.

Further, in the lock mechanism of the present invention as claimed in claim 2, when a decrease in the air pressure is detected by the pressure sensor for detecting the air pressure supplied to the balance mechanism, the drive means and the drive means are driven. And a locking member that locks the arm by driving the.

[0013]

[Function] Even if an abnormality such as an air leak occurs in the balance mechanism or the air pipe that keeps the arm in the swing position by the air pressure, the lock mechanism locks the arm in the swing-disabled state and the arm rotates downward. Can be prevented.

[0014]

1 to 3 show a first embodiment of an industrial robot according to the present invention.

In each figure, an industrial robot 1 is an articulated robot body 2, a control circuit 3 for controlling the robot body 2, a balance mechanism 5 for keeping a first arm 4 of the robot body 2 stationary. An air supply unit 6 for supplying compressed air to the piston-cylinder mechanism 18 of the balance mechanism 5. The balance mechanism 5 is composed of a piston-cylinder mechanism 18 and a spring 19 built in the piston-cylinder mechanism 18, as will be described later.

The robot body 2 is provided with a swivel base 7 provided on a fixed base 7a and horizontally rotatable, an abutment 8 provided on the swivel base 7, and an upright position on the abutment 8 to rotate in the front-rear direction. A first arm 4 which is movably supported, a second arm 9 which is supported on an upper end of the first arm 4 and extends in a horizontal direction, and a wrist portion 10 which is provided at a tip of the second arm 9.
And consists of.

A pair of motor mounting portions 8 are mounted on the abutment 8.
a and 8b are projected. A drive motor 11 for driving the first arm 4 is attached to one motor attachment portion 8a, and a second arm 9 is attached to the other motor attachment portion 8b.
A drive motor 12 for driving the motor is attached. The rotor (not shown) of the drive motor 11 is fixed to the flange portion 4A of the first arm 4, and the first arm 4 is rotated in the front-rear direction about the B axis by the driving force of the drive motor 11.

Further, a pair of motor mounting portions 8 on the abutment 8
The fixed base 8c projects between the a and 8b, and the fixed base 8c
A lock mechanism 41 is provided in c. The lock mechanism 41 is the piston-cylinder mechanism 1 of the balance mechanism 5.
The flange portion 65 of the drive motor 11 fixed to the flange portion of the first arm 4 is locked on a path different from 8 to lock the first arm 4 at an arbitrary stop position. Therefore, even when the balance mechanism 5 cannot stop the first arm 4 due to air leakage or the like, the first arm 4 is held at that position by the lock mechanism 41.

The rotor (not shown) of the drive motor 12 is connected to the flange portion 13A of the horizontal link 13 extending rearward. The tip of the horizontal link 13 is connected to the lower end of a vertical link 14 that extends in the vertical direction behind the first arm 4. The upper end of the vertical link 14 is connected to the rear portion 9a of the second arm 9 supported by the upper end 4a of the first arm 4. Therefore, the rotational driving force of the drive motor 12 is transmitted to the second arm 9 via the horizontal link 13 and the vertical link 14.

Further, the second arm 9 is B of the first arm 4.
It rotates up and down around a C axis parallel to the axis. The wrist portion 10 provided at the tip of the second arm 9 is configured to rotate in three axial directions around the D, E, and F axes, and a working jig such as a coating gun is attached to the F axis. It is attached.

The rear portion 9a of the second arm 9 has wrist drive motors 15, 16 for driving the wrist portion 10 in the respective axial directions.
17 are stored. In the balance mechanism 5, the lower end of the piston-cylinder mechanism 18 is connected to the fixed base 8c, and the upper end is connected to the side surface of the first arm 4.

Now, the structures of the balance mechanism 5, the air supply unit 6, and the lock mechanism 41 described above will be described.

As shown in FIG. 3, the balance mechanism 5 includes the first
The piston-cylinder mechanism 18 and the spring 19 formed of a compression coil spring provided in the piston-cylinder mechanism 18 are miniaturized.

The upper end 20a of the cylinder portion 20 of the piston-cylinder mechanism 18 is rotatably connected to the side surface of the first arm 4. A piston 21 is slidably provided inside the cylinder portion 20, and a piston rod 22 connected to the center of the lower surface of the piston 21 is provided in the cylinder portion 2.
0 through the bottom central hole 20c and extends downward.

The lower end 22a of the piston rod 22
Is rotatably connected to the fixed base 8c of the abutment 8 described above.

Therefore, in the piston-cylinder mechanism 18, as shown in FIG. 3, when the first arm 4 rotates in the vertical direction (B ₂ direction), the piston 21 moves upward in the cylinder portion 20 and is compressed, When the first arm 4 rotates in the horizontal direction (B ₁ direction), the piston 21 moves downward in the cylinder 20 and extends.

The piston 21 is mounted so as to slide with a stroke from the upper end position P ₁ to the lower end position P ₂ as shown in FIG. Therefore, when the first arm 4 stands upright, the piston 21 moves to the upper end position P.
_When reaching ₁ and the first arm 4 rotates to the lower limit position in the horizontal direction, the piston 21 moves to the lower end position P ₂ .

The piston 21 has the upper chamber 2 inside the cylinder portion 20.
0d and the lower chamber 20e are defined, and a seal member (not shown) such as an O-ring is attached to the outer periphery thereof.

Further, in the bottom central hole 20c of the cylinder portion 20,
Supports the piston rod 22 slidably and
A sealing member (not shown) for tightly sealing is provided.
It An intake port 20f is provided near the bottom of the lower chamber 20e.
The upper end position P of the piston 21 ₁Located above
An exhaust port 20g is provided above the chamber 20d.

Further, the piston 21 is pressed upward in the entire stroke by the pressing force of the spring 19 having a small spring constant, and the piston-cylinder mechanism 18 is in a compressed state and is perpendicular to the first arm 4 (B ₂ Force).

The air supply unit 6 as shown in FIG.
Air is supplied to the cylinder part 20 so as to cooperate with the spring 19, and the lower chamber 20e of the cylinder part 20 is supplied via air pipes 25a to 25c for supplying compressed air generated by an air source 24 such as a compressor. Intake port 20f
It is connected to the. Further, the air pipe 25a has an opening / closing valve 26,
A check valve 27 and a pressure reducing valve 29 are provided.

The on-off valve 26 is a valve that is opened or closed manually and is normally open. The check valve 27 is configured to allow only the flow of air supplied from the air source 24 to the cylinder portion 20 and stop the flow of air flowing backward from the cylinder portion 20. Further, the air from the air source 24 is depressurized to a constant pressure by a pressure reducing valve 29 with a relief mechanism and supplied to the lower chamber 20e of the cylinder portion 20.

Reference numeral 30 is a solenoid valve composed of a 2-port 2-position spring offset valve, which opens when the solenoid 30a is excited by a signal from the control circuit 3 and opens.
When the solenoid 30a is demagnetized by turning off the signal from, the valve is closed by the pressing force of the spring 30b. Normal solenoid valve 30
Is opened and the air whose pressure is made constant by the pressure reducing valve 29 is supplied to the lower chamber 2 of the cylinder portion 20 through the air pipes 25a to 25c.
0e.

Sensor pipe 4 branched from the air pipe 25c
2, a pressure sensor 31 is arranged. The pressure sensor 31 detects the air pressure supplied to the lower chamber 20e of the cylinder portion 20 and outputs the detection signal to the control circuit 3.
That is, when the supply air pressure drops due to the damage of the air pipe 25 or the failure of the compressor, the control circuit 3 stops the power supply from the power source 33. Therefore, solenoid 3
0a is demagnetized, the solenoid valve 30 is closed, and the cylinder portion 20
The air supply to the robot main body 2 is stopped and the robot main body 2 is also stopped. Further, when the operator manually turns off the emergency stop switch 36 in an emergency, the solenoid 30 of the solenoid valve 30
When a is demagnetized, the first arm 4 of the robot body 2 is stopped.

As described above, the piston 21 has the spring 1
It is pressed upward by the pressing force of 9 and the air pressure, and by this resultant force, the first arm 4 can be held at its rotating position. For example, when the first arm 4 rotates in the horizontal direction (B ₁ direction) from the position shown in FIG. 4, the gravitational moment acting on the first arm 4 increases. In that case, the piston 21 in the cylinder portion 20 moves downward and compresses the spring 19. At the same time, the volume of the lower chamber 20e that presses the piston 21 decreases, and the air in the lower chamber 20e is also compressed and pressurized. Therefore, as the first arm 4 rotates in the B ₁ direction, the force F of the balance mechanism 5 on the first arm 4 increases due to the air pressure and the spring force, and the force of gravity acting on the first arm 4 increases. balance. As a result, the first arm 4 stands still at the rotation position.

On the contrary, when the first arm 4 is rotated in the vertical direction (B ₂ direction), the gravitational moment acting on the first arm 4 is reduced. In this case, the cylinder part 2
The piston 21 in 0 moves upward, the spring 19 extends, and the pressing force thereof decreases. At the same time, the volume of the lower chamber 20e increases and the pressure in the lower chamber 20e temporarily decreases, but immediately the air from the air source 24 is supplied via the air pipes 25a to 25c and returns to a constant pressure.

Therefore, the first arm 4 is balanced and stably held at any angle. Therefore, for example, when the operator directly supports the tip of the second arm 9 to perform the direct teaching operation, the operator can move the first arm 4 with a small operation force, and the teaching operation can be easily performed.

The balance mechanism 5 including the piston-cylinder mechanism 18 and the spring 19 is small, and the first arm 4 is stationary in a stable state balanced by the balance mechanism 5 over the entire range. The load of the motor 11 that drives the arm 4 of the
It is also possible to use a small motor with a small driving force.

Further, when the air pressure supplied from the air source 24 drops to a pressure equal to or lower than the pressure required to hold the first arm 4 due to some failure, the control circuit 3 detects the detected signal from the pressure sensor 31. To close the solenoid valve 30,
At the same time, the power supply to the robot body 2 is stopped. And
The control circuit 3 demagnetizes the solenoid 43a of the solenoid valve 43 of the lock mechanism 41 described later, and the
The air in the second chamber 45b of No. 4 is exhausted. As a result, the lock mechanism 41 operates in the locked state and stops the first arm 4. Therefore, the first arm 4 is connected to the air source 2
Even if the air pressure from 4 is reduced, it is held still at that position and is prevented from rotating downward by its own weight.

Reference numeral 43 is a solenoid valve consisting of a 3-port 2-position spring offset valve, which opens when the solenoid 43a is excited by a signal from the control circuit 3 and opens.
When the solenoid 43a is demagnetized by turning off the signal from, the valve is closed by the pressing force of the spring 43b. Normal solenoid valve 43
Opens and supplies the air whose pressure is made constant by the pressure reducing valve 29 to the piston-cylinder mechanism 44 of the lock mechanism 41 through the air pipes 25a and 25d.

The piston-cylinder mechanism 44 is a single-acting retractable cylinder in which a piston 46 is slidably inserted in a cylinder portion 45, and is compressed in a first chamber 45a defined by the piston 46. The spring 47 is interposed, and the compressed air from the air pipes 25a and 25d is supplied to the second chamber 45b. Therefore, the piston rod 48 integrated with the piston 46 is constantly pressed in the X ₂ direction by the pressing force of the spring 47, but slides in the X ₁ direction by the switching operation of the electromagnetic valve 43.

That is, when the solenoid 43a of the solenoid valve 43 is excited, the compressed air from the air source 24 is transferred to the second chamber 45.
piston 46 and piston rod 4 to be supplied to b
8 slides in the X ₁ direction against the spring force of the spring 47 and is displaced to the unlocked position M ₁ . At that time, the first chamber 4
The air in 5a is exhausted from the exhaust port 49.

When the solenoid 43a of the solenoid valve 43 is demagnetized, the supply of compressed air is cut off, so that the piston 4
6 and the piston rod 48 slide in the X ₂ direction by the spring force of the spring 47. At that time, the air in the second chamber 45b is exhausted from the exhaust port 43c of the electromagnetic valve 43.

Sensor pipe 5 branched from the air pipe 25d
At 0, a pressure sensor 51 is arranged. The pressure sensor 51 detects the air pressure supplied to the second chamber 45b of the cylinder portion 45 and outputs the detection signal to the control circuit 3. That is, when the supply air pressure drops due to damage to the air pipes 25a and 25d or a failure of the compressor, the control circuit 3 stops energization from the power source 33. Therefore, the solenoid 43a is demagnetized, the solenoid valve 43 is closed, the air supply to the cylinder portion 45 is stopped, and the robot body 2 is also stopped. When the operator manually turns off the emergency stop switch 36 in an emergency, the solenoid valve 3
The 0 solenoid 30a is demagnetized, the lock mechanism 41 is locked, and the first arm 4 of the robot body 2 is locked.

Next, the lock mechanism 41 which is an essential part of the present invention will be described.

The lock mechanism 41 is switched to the locked state or the unlocked state by the solenoid valve 43 and the piston-cylinder mechanism 44.

As shown in FIG. 5, the piston-cylinder mechanism 44 is attached to the vertical portion 54a of the L-shaped bracket 54 by the bolt 53. The horizontal portion 54b of the bracket 54 is fixed on the fixed base 8c of the abutment 8 by bolts 55. Furthermore, the piston-cylinder mechanism 4
The piston rod 48 of No. 4 is fixed to the link 56. As shown in FIG. 6, the link 56 is loosely fitted in the hole 57c formed in the vertical portion 57a of the bracket 57 and is displaceable in the X ₁ and X ₂ directions together with the piston rod 48 of the piston-cylinder mechanism 44. It is provided.

The link 56 has a cylindrical guide shaft 58.
A lock rod 59 penetrating the guide shaft 58 is attached. As shown in FIG. 7, in the guide shaft 58, the flange portion 58 a is attached to the vertical portion 5 of the bracket 57 by the bolt 60.
7a, and the locking rod 5 is provided in the through hole 58b.
Slide bearings 61 and 62 for receiving the radial load of 9 are provided. The horizontal portion 57b of the bracket 57 is the bolt 6
It is fixed on the fixed base 8c of the abutment 8 by 3.

Further, one end of the locking rod 59 has the link 5
It is inserted into the sixth hole 56a, the retaining ring 64 and having a step for and preventing movement of the X ₁ direction X ₂
It is prevented from falling off in the direction.

[0050] Further, the outer periphery of the locking rod 59 groove 59 ₁ ～59N are provided at regular intervals, the tip portion 59a of the lock rod 59 than the guide shaft 58 X
It projects in _two directions. The brackets 54 and 57 are
Is detachably fixed so that the piston-cylinder mechanism 44 can be easily inspected and the locking rod 59 can be replaced.

As shown in FIG. 8, on the flange 65 fixed to the rotor (not shown) of the drive motor 11 for driving the first arm 4, the tip portion 5 of the locking rod 59 is attached.
A locking ring 66 is fixed at a position facing 9a. This locking ring 66 has locking holes 66 at regular intervals.
a (66a ₁ ~66a _n) is bored. Since each of the locking holes 66a _{1 to} 66a _n has a diameter slightly larger than that of the locking rod 59, if the piston rod 48 of the piston-cylinder mechanism 44 is displaced in the X ₂ direction, the locking rod 59 will be described later. Fits into any of the locking holes 66a _{1 to} 66a _n .

The operation of the lock mechanism 41 having the above structure will be described.

For example, when air leaks occur in the air pipes 25a to 25d or the piston-cylinder mechanism 18 and the pressure sensors 31 and 51 detect this, the power supply 33 shuts off the power supply to the control circuit 3 and the solenoid valves 30, The solenoids 30a and 43a of 43 are demagnetized.

When the solenoid 43a of the solenoid valve 43 is demagnetized, the second chamber 45b of the piston-cylinder mechanism 44 and the exhaust port 43c of the solenoid valve 43 communicate with each other, and the air in the second chamber 45b is connected to the air pipe 25d and the exhaust port. It is discharged via 43c.

Piston 4 of piston-cylinder mechanism 44
The piston rod 48 integrated with 6 is displaced in the X ₂ direction by the pressing force of the spring 47 and projects to the outside of the cylinder portion 45. The link 56 fixed to the piston rod 48 is displaced in the same direction, and the locking rod 59 fixed to the link 56 slides in the guide shaft 58 and projects in the X ₂ direction. In this way, the tip 59a of the locking rod 59 protruding from the guide shaft 58 has the locking hole 66a formed in the locking ring 66 of the flange 65 integrally fixed to the first arm 4. _When any of _{1 to} 66a _n is matched, the fitting hole is fitted.

In this way, the first arm 4 is locked and stopped by the engagement of the locking rod 59 and the locking ring 66.

However, the tip portion 59 of the locking rod 59
a is If no match any of the locking holes 66a ₁ ~66a _n of the locking ring 66, the distal end portion 59a abuts against the side surface of the locking ring 66 by the pressing force of the spring 47. The piston-cylinder mechanism 18 of the balance mechanism 5 that holds the first arm 4 in the stopped state disconnects between the air pipes 25a and 25c when the solenoid 30a of the solenoid valve 30 is demagnetized as described above. As a result, the lower chamber 20e of the cylinder portion 20 is hermetically sealed to prevent air from flowing out into the lower chamber 20e. Therefore, the lock of the piston-cylinder mechanism 18 holds the first arm 4 in that position.

However, if there is an air leak in the piston-cylinder mechanism 18 or the air pipe 25c, the control circuit 3 closes the solenoid valve 30 and demagnetizes the solenoid valve 43 at the same time to demagnetize the solenoid valve 43 to lock the lock mechanism 41, as described above. The lower chamber 2 of the piston-cylinder mechanism 18 is operated in the locked state.
As the air pressure in 0e decreases, the arm 4 slowly starts to rotate in the B ₁ direction due to its own weight. Therefore, with respect to the distal end portion 59a of the locking rod 59, one of the locking holes 66a ₁ ~66a _n drilled in the locking ring 66 of the flange 65 provided integrally with the arm 4 is coincident. Then, the tip portion 59a of the locking rod 59 is fitted to one of the matching locking holes 66a ₁ ~66a _n to lock the arm 4.

Further, when the operator mistakenly rotates the arm 4 and turns on the power to start the drive motor 11, the lock rod 59 has grooves 59 ₁ to 59 n on the outer periphery thereof. The tip portion 59a of the locking rod 59 is cut by the groove 59 ₁ projecting from the guide shaft 58 by the shearing force when the locking ring 66 of the flange 65 rotates. As a result, the piston-cylinder mechanism 44 of the lock mechanism 41 can be prevented from being damaged, and at the same time, the kinetic energy for rotating the arm 4 is absorbed by the cutting of the tip 59a of the locking rod 59, and the arm 4 is decelerated. To be done.

Further, the locking rod 59 is a piston-
Due to the pressing force of the spring 47 of the cylinder mechanism 44, X ₂
Since the end portion of the cut locking rod 59 coincides with the next locking hole 66, the locking hole 6 is urged in the direction.
6 and lock the locking ring 66. Therefore,
Even if the arm 4 is to be rotated while air leakage occurs, the locking rod 59 can be fitted into the next facing locking hole 66a to prevent this.

[0061] Further, the locking rod 59 is a plurality of grooves 59 ₁ ～59N also provided on the outer circumference is cut tip 59a, and a piston - spring 47 of the cylinder mechanism 44
It can be repeatedly used for the stroke of the piston 46 (positions M _{1 to} M _{2 in} FIG. 4) urged in the X ₂ direction by the pressing force. Therefore, the locking rod 59 does not need to be replaced every time air leaks, and maintenance is easy.

9 to 12 show a second embodiment of the present invention.

In each figure, the lock mechanism 71 is configured to lock the gear 72 integrally provided on the arm 4 when the air supply from the air supply unit 6 is stopped. Gear 72 of the plurality of external teeth 72a (72a ₁ ~72a _n)
The lock mechanism 71 is provided on the fixed portion 8c of the support 8 located below the gear 72.

The lock mechanism 71 includes a base 73 fixed to the fixed portion 8c of the support 8, a lock lever 75 rotatably supported by a shaft 74 at one end of the base 73, and a base 73.
And a lock lever 75, the piston-cylinder mechanism 44 is configured to rotate and displace the lock lever 75. In the piston-cylinder mechanism 44, the end portion 45a of the cylinder portion 45 is rotatably supported by the shaft 77 on the other end side of the base 73, and the tip end portion 48a of the piston rod 48 protruding from the cylinder portion 45 is substantially the lock lever 75. It is supported by a shaft 79 provided at an intermediate position.

The cylinder 45 of the piston-cylinder mechanism 44 is supplied with compressed air from the air supply unit 6 as in the above embodiment.

Now, the operation of the lock mechanism 71 will be described.

Normally, the solenoid valve 43 shown in FIG. 4 is excited, and compressed air from the air source 24 is supplied to the air pipes 25a, 2a.
It is supplied to the second chamber 45b of the cylinder portion 45 via 5d. Therefore, in the piston-cylinder mechanism 44, the piston 46 is displaced in the X ₁ direction against the spring 47, and the piston rod 48 is retracted into the cylinder portion 45. Thus, normally, the lock lever 75 is C ₁
The gear 72 can rotate with the arm 4 in a lock release position in which the gear 72 rotates in the direction and is separated from the gear 72.

However, if there is an air leak in the air pipes 25a to 25d or the piston-cylinder mechanism 18, the solenoid 43a of the solenoid valve 43 is demagnetized and the solenoid valve 43 is switched to supply air to the cylinder portion 45 of the piston-cylinder mechanism 44. Be cut off. Therefore, the piston 46 in the cylinder portion 45 is displaced in the X ₂ direction by the pressing force of the spring 47, and the piston rod 48 is pushed out of the cylinder portion 45.

As a result, as shown in FIG. 12, the lock lever 75 rotates in the C ₂ direction, and the tip end portion 75a of the lock lever 75 has the teeth 72a (72a _{1 to} 72a ₂ ) of the gear 72.
Fit in between. Therefore, the gear 72 is locked by the lock lever 75.
Is locked in a non-rotatable state, and the arm 4 is also locked.

13 and 14 show the third embodiment of the present invention.

In both figures, the lock mechanism 81 is configured to lock the cam 82 provided integrally with the arm 4 when the air supply from the air supply unit 6 is stopped. A plurality of projections 82a cam 82 on the outer circumference (82a ₁ to 82
a _n ) protrudes in a rectangular shape, and the lock mechanism 81 is provided on the fixed portion 8c of the abutment 8 located below the cam 82.

The lock mechanism 81 includes a first lock lever 84 supported by a shaft 83 supported by a bracket 8d of a fixed portion 8c of the abutment 8, and a first lock lever 84 connected to an intermediate position of the first lock lever 84. The second lock lever 85 and the piston-cylinder mechanism 44 that rotationally displaces the second lock lever 85. In the piston-cylinder mechanism 44, the end portion 45a of the cylinder portion 45 is connected to the shaft 86 supported by the bracket 8e of the fixed portion 8c of the support 8. Also, the first
The lock lever 84 and the second lock lever 85 are formed in an X shape because their intermediate positions are rotatably connected by a connecting pin 87. The piston rod 48 of the piston-cylinder mechanism 44 is connected to the other end of the second lock lever 85 via a connecting pin 88.

The cylinder 45 of the piston-cylinder mechanism 44 is supplied with compressed air from the air supply unit 6 as in the above embodiment.

The operation of the lock mechanism 81 will be described below.

Normally, the solenoid valve 43 shown in FIG. 4 is excited and compressed air from the air source 24 is supplied to the air pipes 25a, 2a.
It is supplied to the second chamber 45b of the cylinder portion 45 via 5d. Therefore, in the piston-cylinder mechanism 44, the piston 46 is displaced in the X ₁ direction against the spring 47, and the piston rod 48 is retracted into the cylinder portion 45. Thus, normally, the lock levers 84, 85
Tip portions 84a and 85a of the cam descend in the Z ₂ direction to move the cam 82
The cam 82 can rotate together with the arm 4 in the unlocked position further apart.

However, when there is an air leak in the air pipes 25a to 25d or the piston-cylinder mechanism 18, the solenoid valve 43a of the solenoid valve 43 is demagnetized and the solenoid valve 43 is switched to supply air to the cylinder portion 45 of the piston-cylinder mechanism 44. Be cut off. Therefore, the piston 46 in the cylinder portion 45 is displaced in the X ₂ direction by the pressing force of the spring 47, and the piston rod 48 is pushed out of the cylinder portion 45.

As a result, as shown in FIG. 14, the other end of the lock lever 85 is pressed in the X ₂ direction. Since the pair of lock levers 84 and 85 are rotatably connected by the connecting pin 87, the tip end portions 84a and 85a ascend in the Z ₁ direction and contact the cam 82 while rotating in opposite directions. Therefore, the tip end 75a of the lock lever 75 has a rectangular protrusion 82a (82a) provided on the outer periphery of the cam 82.
_{1 to} 82a _n ). Therefore, the cam 82 is locked in a non-rotatable state by the pair of lock levers 84 and 85, and the arm 4 is also locked.

FIG. 15 shows a modified example of the air supply unit 6.

In the figure, the solenoid valve 30 of the air supply unit 6
Instead of the above, an air actuating valve 91 which is switched by turning on / off an air signal of the air pipes 25b and 25c is provided. A pressure reducing valve 9 is provided in the air pipe 25e branched from the air pipe 25a.
Two are provided. The air pipe 25f branched from the air pipe 25d on the downstream side of the solenoid valve 43 is connected to the operation port 91a of the air operation valve 91.

Further, the pressure sensor 51 detects the air pressure in the air pipe 25d arranged downstream of the solenoid valve 43 via the air pipe 25f, and the solenoid valve 43 detects the pressure sensor 5
When 1 detects a pressure drop in the air pipe 25d, the solenoid portion 43a is demagnetized and switches.

Therefore, the solenoid valve 43 is normally excited, the compressed air from the air source 24 is depressurized by the pressure reducing valve 92 to a predetermined pressure necessary for the unlocking operation, and the air pipe 25
It is supplied to the second chamber 45b of the cylinder portion 45 via e and 25d. Therefore, the piston-cylinder mechanism 44
Then, the piston 46 is displaced in the X ₁ direction against the spring 47, and the piston rod 48 is retracted into the cylinder portion 45 to be in the unlocked state.

The air supplied to the air pipes 25e and 25d is also supplied to the operation port 91a of the air operated valve 91 through the air pipe 25f. Therefore, the air operated valve 91 is normally opened, and the compressed air from the air source 24 is supplied to the piston-cylinder mechanism 18 of the balance mechanism 5 via the air pipes 25a to 25c.

However, when air leakage occurs in the air pipes 25a to 25f, the pressure sensor 51 outputs the detection signal to the control circuit 3, and the control circuit 3 demagnetizes the solenoid portion 43a of the solenoid valve 43. Solenoid valve 43 is solenoid 43a
Is demagnetized, switching is performed by the pressing force of the spring 43b, and the air supply to the cylinder portion 45 of the piston-cylinder mechanism 44 is cut off. Therefore, the piston 46 in the cylinder portion 45 is displaced in the X ₂ direction by the pressing force of the spring 47, and the piston rod 48 is pushed out of the cylinder portion 45 to be locked.

At the same time, the operating port 9 of the air operated valve 91
The air signal to 1a is turned off, and the air actuated valve 91 switches to the closed state. Therefore, in the piston-cylinder mechanism 18, the air pipe 25c is shut off and the piston 21 is locked. Therefore, in the unlikely event that the piston-cylinder mechanism 18
Even if air leakage occurs in the piston-cylinder mechanism 4
Since 4 is in the locked state, it is possible to prevent the arm 4 from rotating in the descending direction by its own weight.

Although the balance mechanism 5 for holding the first arm 4 has been described in the above embodiment, the present invention is not limited to the second embodiment.
It is needless to say that the present invention can also be applied to hold the arm 9 of FIG. 1 or the arm of a robot having a configuration other than the above.

When holding the first arm 4, one end of the piston-cylinder mechanism 18 is connected to the first arm 4 and the other end is connected to the abutment 8 on the swivel base 7. When the second arm 9 is held, the piston-cylinder mechanism 18 has one end connected to the second arm 9 and the other end connected to the first arm 4 or the abutment on the swivel base 7 while functioning as a support portion. Therefore, the first arm 4 or the abutment 8 functions as a support portion.

Further, in the above embodiment, the spring 19 is provided in the cylinder portion 20 of the piston-cylinder mechanism 18, but not limited to this, for example, the spring 19 may be provided outside the cylinder portion 20. Alternatively, the spring 19 may be provided separately from the piston-cylinder mechanism 18, that is, may be stretched between the abutment 8 and the first arm 4 so as to be parallel to the piston-cylinder mechanism 18.

Further, although the piston-cylinder mechanism is used as the balance mechanism in the above-mentioned embodiment, the invention is not limited to this. The balance mechanism may be configured by supplying compressed air into the dynamic actuator.

[0089]

As described above, in the industrial robot according to the present invention, even if an abnormality such as an air leak occurs in the balance mechanism or the air piping that causes the arm to stand still at its swing position by the air pressure, the lock mechanism has the arm. Can be locked so that the arm cannot rotate downward by its own weight,
Further, even when direct teaching is performed, when the air pressure of the balance mechanism drops, the balance mechanism can be locked to prevent the arm from rotating by its own weight, so that the safety can be further enhanced. Further, since the arm can be fixed by the lock mechanism, inspection and replacement work of the balance mechanism can be performed more easily and safety at the time of work is secured. Furthermore, since the lock mechanism can prevent the arm from tilting due to air leakage, the arm does not exceed the setting range of the control program, and the operator does not need to perform a reset operation before operating the robot. Moreover, since the air supply system path to the balance mechanism and the lock mechanism is shared, the air supply system path is simplified and the assembling work can be easily performed.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a first embodiment of an industrial robot according to the present invention.

FIG. 2 is a perspective view of a robot body.

FIG. 3 is a view showing a balance mechanism attached to a first arm.

FIG. 4 is a system diagram of a control circuit, an air supply unit, and a piston-cylinder mechanism.

FIG. 5 is an enlarged view of a lock mechanism.

FIG. 6 is a plan view of a lock mechanism.

FIG. 7 is a view from the direction of the arrow D in FIG.

8 is a vertical sectional view taken along the line EE in FIG.

FIG. 9 is a front view of the robot body according to the second embodiment of the present invention.

FIG. 10 is a perspective view of a lock mechanism according to a second embodiment of the present invention.

FIG. 11 is a side view of the lock mechanism according to the second embodiment of the present invention.

FIG. 12 is a side view showing a locked state of the lock mechanism according to the second embodiment of the present invention.

FIG. 13 is a side view showing a lock mechanism according to a third embodiment of the present invention.

FIG. 14 is a side view showing a locked state of the lock mechanism according to the third embodiment of the present invention.

FIG. 15 is a system diagram showing a modified example of the air supply unit.

[Explanation of symbols]

1 Industrial Robot 2 Robot Main Body 3 Control Circuit 4 First Arm 5 Balance Mechanism 6 Air Supply Unit 8 Abutment 9 Second Arm 18,44 Piston-Cylinder Mechanism 19 Spring 20,45 Cylinder 21,46 Piston 22, 48 Piston rod 24 Air source 25a-25f Air piping 28 Air tank 29 Pressure reducing valve 30,43 Electromagnetic valve 31,51 Pressure sensor 41,71,81 Lock mechanism 56 Link 58 Guide shaft 59 Locking rod 66 Locking ring 66a ( 66a ₁ ~66a _n) locking hole 73 base 75 the lock lever 82 the cam 84 first lock lever 85 the second lock lever 87 the coupling pin

Claims (2)

[Claims] 1. An arm swingably supported, one end of which is connected to the arm, and the other end of which is connected to a support portion which supports the arm, and the arm is kept stationary at the swing position by air pressure. An industrial robot comprising: a balance mechanism; and a lock mechanism that locks the arm in a non-pivotable state when air leakage occurs in the balance mechanism. 2. The lock mechanism includes a driving unit that is driven when a decrease in the air pressure is detected by a pressure sensor that detects the air pressure supplied to the balance mechanism, and the arm is driven by the driving unit. The industrial robot according to claim 1, further comprising: a locking member for locking the.