JPH0444317Y2 - - Google Patents

Description

[Detailed explanation of the invention] [Industrial application field] This invention prevents accidents by detecting work overloads applied to the robot and making an emergency stop when performing welding work etc. using an industrial robot. The present invention relates to an overload detection device used for

[Prior Art] Industrial welding robots that are generally used for welding work, etc. are generally constructed as shown in FIG.

That is, the welding robot 5 used for this welding work has a swinging post 9 vertically mounted on a base 8 so as to be rotatable in the direction shown by arrow A, and a swinging post 9 that swings in the direction shown by arrow B. Attach arm 6. A power supply transformer 7b and a welding chip 7a are connected to the free end of this swing arm 6 via an inclined shaft 6a that is rotatable in the direction shown by arrow C or arrow D.
A welding gun 7 having the following functions is attached.

Note that 10 is a hanging tool, 11 is a chucking mechanism, 12 is a floating unit, 13 is a frame, and 2 is a workpiece pedestal.

[Problems to be solved by the invention] When performing welding work using the welding robot 5 having such a configuration, it is necessary to When spot welding is performed with foreign matter interposed between the welding surfaces, the welding tip 7a may be welded to the workpiece. Furthermore, if a part of the workpiece is deformed, it may get caught on the welding tip 7a. In such a case, the robot will move the welding gun 7 to the next welding location according to the program.
If an attempt is made to move the welding gun 7 with a strong force, an excessive load will be placed on the welding gun 7. In such a case, safety measures have been taken to detect an abnormality from the load on the motor of the welding robot 5 and stop the robot. However, this safety measure cannot always be expected to operate reliably, and moreover, it is necessary to ensure that the robot itself can escape from overload. Since the welding tip 7a of the welding gun 7 is not equipped with a configuration for setting a so-called deformation allowance that allows relative deformation between the robot and the swinging arm 6, the welding tip 7a of the welding gun 7 is bend,
There were problems such as breakage, deformation of the arm of the welding gun 7, or damage to the drive shaft unit of the robot.

In view of the above points, the present invention is configured to immediately detect an overload when a robot is working on the robot, stop the robot's work operation, and set a deformation amount to remove the overload. Another object of the present invention is to provide a new overload detection device for an industrial robot that can easily return the deformation to its original predetermined position after the cause of the overload has been removed.

[Means for solving the problem] The overload detection device for industrial robots of the present invention is installed between the robot's wrist tip shaft and a working machine such as a welding machine. The work equipment is held in a predetermined position relative to the shaft, and when an overload due to an external force is applied to the work equipment, the work equipment is elastically displaced and deformed to the extent that it can return to its original predetermined position. It is characterized by being configured so that it can be detected.

[Function] By configuring as described above, when an overload is applied to the work equipment due to an external force, the overload condition can be electrically detected, and this signal can be used to automatically stop the robot's work operation. In addition,
The overload detection device of this industrial robot is elastically deformed and prevents malfunctions such as deformation of parts due to overload. Moreover, after the cause of the overload is removed, the work equipment can be restored to its original state. It has the effect of being able to return to a predetermined position and restart the work.

[Embodiment] Hereinafter, an embodiment of the overload detection device for an industrial robot according to the present invention will be described with reference to FIGS. 1 to 7. Note that in FIGS. 1 to 7, parts corresponding to those in FIG. 8 are designated by the same reference numerals, and detailed explanation thereof will be omitted.

FIG. 2 is an overall perspective view of a welding robot to which an overload detection device for an industrial robot is attached, showing a first embodiment of the present invention, and 5 is the main body of the welding robot. This welding robot 5 has a swing post 9 mounted on a base 8, a swing arm 6 installed on the top thereof, and a robot wrist tip shaft 15 installed at the free end of the swing arm 6.

A spot welding gun 21, which is a working device, is attached to the robot wrist tip shaft 15 via an overload detection device 20.

This overload detection device 20 is attached to the robot wrist tip shaft 15 by fixing an upper fixing plate 22 with bolts 23, as shown in the longitudinal section of FIG.
The upper fixing plate 22 is formed into a disk shape as shown in FIG. 3, and has a circular through hole 24 in its center.

Further, the upper end of a fixing bracket 25 formed of a rectangular frame shaped like a column is fixed to the center of the lower surface of the upper fixing plate 22, and the center of a fixing plate 26 is fixed to the lower end of the fixing bracket 25.

A circular insertion opening 27 is provided in the center of the fixed plate 26.

Furthermore, holding holes 28, which are cylindrical holes for freely rotating the steel balls 31, are provided at required locations on the lower surface of the fixed plate 26, which constitute the positioning and displacement means, for freely rotating the steel balls 31 therein. Furthermore, a movable plate 2 is provided at the bottom of the fixed plate 26.
This movable plate 29 is a circular plate of the same shape as the fixed plate 26, and the required locations on the upper surface of the movable plate 29 are divided into six equal parts corresponding to the six holding holes 28 of the fixed plate 26. A positioning hole 30, which is a dovetail-shaped hole, is provided for positioning the steel ball 31. In addition, this positioning hole 30
is a cross section V of the movable plate 29 extending in the radial direction
It may be replaced with a letter-shaped groove. Furthermore, this holding hole 28 and the corresponding positioning hole 3
0 may be configured so that three or more sets are provided. Further, a positioning hole 30 is provided in the fixed plate 26, and a holding hole 28 is provided in the movable plate 29, so that the steel balls 3
1 may be installed.

Furthermore, an insertion hole 43 is provided in the center of the movable plate 29 for passing a bolt through.

Then, the steel balls 31 are installed in the spaces between the holding holes 28 and the positioning holes 30, which are aligned with each other.

Note that instead of the steel ball 31, a hemispherical convex portion or the like may be formed integrally with the fixing plate 26.

Plate biasing means is provided for the positioning and displacement means configured in this manner.

Therefore, the fixed plate 26 and the movable plate 29
A support bolt 32 serving as a support body is inserted into the circular insertion opening 27 and the insertion hole 43, which communicate with each other in a state where the
Insert. Furthermore, the end of the compression coil spring 33 is pressed against the tip of the support bolt 32. After fitting the washer 34, a locking nut 35 with a locking member is screwed on, and the locking nut 35 is tightened with a locking lock 36 to fix it.

In addition, the head of the support bolt 32 is provided with a locking bolt 36 for the nut 35 fitted to the tip of the support bolt 32.
An anti-rotation stopper may be provided to prevent the bracket from rotating toward the fixed bracket 25.

As a result, the movable plate 29 is pressed against the fixed plate 26 with a required biasing force via the steel balls 31, so that due to the action of the spherical surface of the steel ball 31 and the conical slope of the positioning hole 30, a predetermined It is positioned at a certain position.

Further, as a displacement detection means, a support plate 37 is provided in the vicinity of the upper fixing plate 22 of the above-mentioned fixing bracket 25, and a support plate 37 is provided to protrude laterally.
Set up. The switch lever 39 of the micro switch 38 contacts the head of the support bolt 32 in a normal state to turn the micro switch 38 on.

A lead wire 40 drawn out from this microswitch 38 is drawn out through a through hole formed in the fixed bracket 25 and connected to a control device (not shown).

A spot welding gun 21 is attached to the bottom surface of the movable plate 29 of the overload detection device 20 by fixing its gun bracket portion 41 with fixing bolts 42, 42.

Next, the operation of the overload detection device 20 of this example configured as described above will be explained.

First, the spot welding gun 21 of the welding robot 5
In a normal state where no overload is applied to the overload detector 20, the overload detector 20 positions the spot welding gun 21 at an appropriate position relative to the robot wrist tip shaft 15, as shown in FIG. The micro switch 38 is also in the on state, and the welding work is performed in this state.

If an overload is applied to the spot welding gun 21 during this welding operation, the state shown in FIGS. 4 and 5A occurs, and the compression coil spring 3
The movable plate 29 and the support bolt 32 move against the biasing force 3, and the distance between the fixed plate 26 and the movable plate 29 widens. That is, when the spot welding gun 21 receives an external force in the direction indicated by arrow E in FIG. . Therefore, the support bolt 32
The tip of the switch is separated from the micro switch 38, and the switch lever 39 is opened. For this reason,
The microswitch 38 sends an off-state signal to a control device (not shown), and the control device that receives the signal,
A signal is sent to stop the welding operation of the welding robot 5.

Note that compared to the case where three sets of steel balls 31, their holding holes 28, and positioning holes 30 are provided, six sets of steel balls 31, their holding holes 28, and positioning holes 30 are provided.
In the assembled assembly, the position of the steel ball 31, which is the fulcrum for tilting the movable plate 29, moves away on average, so the displacement distance of the support bolt 32 as the movable plate 29 tilts can be expanded, and the micro switch 38 It is possible to improve the reliability of the operation of turning off the switch.

Also, the overload detection device 20 is indicated by arrow G in FIG. 5A.
When the steel ball 31 receives an external force in the rotational direction shown in FIGS. 5A and 5B, it climbs the slope of the positioning hole 30, causing the fixed plate 26
The movable plate 29 will be pulled away. Therefore, as in the case described above, the tip of the support bolt 32 is pulled away from the micro switch 38, and the micro switch 38 is turned off.
The welding robot 5 is stopped by the control device.

In this way, when an overload is applied to the spot welding gun 21, the welding robot 5 can be stopped quickly, and the necessary deformation allowance for the spot welding gun 21 can be taken, so that when an overload is applied, the welding robot 5 can be stopped quickly. It is possible to avoid troubles such as deformation of the arm of the spot welding gun 21, bending or breaking of the electrode, and failure of the welding robot 5.

After removing the cause of the overload, the spot welding gun 21 is moved by the biasing force of the compression coil spring 33.
Since the welding can be returned to its proper position, welding work can be resumed promptly without any repairs.

Next, a second embodiment of the overload detection device for an industrial robot according to the present invention will be described with reference to FIGS. 6 and 7.

The device of this example is different from the device of the first example described above, except that the support bolt 32 in the plate biasing means is
The structure of the spring 33 and the fixing plate 26 that is installed through the fixing plate 26
The structure of the holding hole 28 is improved.

That is, as shown in FIG.
Instead of the spring 33 inserted through the two parts, a required number of bell springs 50 are used by stacking them so that their convex directions are alternated as shown in the figure.

Alternatively, in order to adjust the elasticity of the bellows spring to a required strength depending on the type of spot welding gun 21 attached to the welding robot 5, such as the weight and size, a bellows spring 50 may be used as shown in FIG. It can be used in various combinations, such as stacking two sheets with their convex directions in the same direction and stacking them as a unit so that their convex directions are alternate.

Furthermore, by adjusting the number of bellows springs stacked and installed on the support bolt 32 in accordance with various spot welding guns 21, the support bolt 3
The amount of displacement extending downward from the fixed plate 26 can be adjusted by elastically deforming the spring 2.
It's advantageous.

Further, in this example device, in the positioning and displacement means, the fixing plate 26 is directly attached to the fixing bracket 25.
Instead of attaching the fixing bracket 2, first
A fixed base plate 51 in the form of a flat plate is fixed to the lower end of the base plate 5 by means such as welding, and insertion holes 52, which are through holes through which fixing screws are inserted, are bored at required locations.

In addition, a thick disk-shaped fixing plate 26 configured as a separate body is prepared, and the above-mentioned fixing base plate 5 is attached to this.
Each screw hole 53 corresponding to each insertion hole 52 of No. 1 is bored in advance.

Then, attach the fixing plate 26 to the fixing bracket 2.
5, and the fixing bolts 54 are screwed into the screw holes 53 through the insertion holes 52 to be fixed.

With this configuration, the fixing plate 26 can be made into a replaceable independent component, and the fixing plate 26 itself can be easily processed such as hardening.

Furthermore, instead of the aforementioned holding hole 28 which is a cylindrical hole, this fixing plate 26 has a holding hole 28a having a hemispherical bottom surface corresponding to the spherical surface of the steel ball 31.
is bored so that the steel ball 31 inserted into the holding hole 28a is supported by the spherical surface. With this configuration, even when a strong force from the steel ball 31 is applied, it is possible to prevent the bottom surface of the holding hole 28 from becoming depressed and causing misalignment.

Note that the configuration, operation, etc. of the second embodiment other than those described in detail above are the same as those of the first embodiment described above, so a description thereof will be omitted.

[Effects of the invention] As detailed above, according to the overload detection device for an industrial robot of the present invention, a positioning displacement means is provided, and furthermore, the fixed plate and the movable plate are in the proper position under normal conditions. A plate biasing means for biasing is provided, and when an overload is applied, the space between the fixed plate and the movable plate is deformed to open against the biasing force of the plate biasing means to relieve the overload. The system is designed to protect the equipment, and the displacement detection means electrically detects displacement due to overload, so when an overload is applied to the spot welding gun, the welding robot can be reliably and quickly activated. It is possible to stop the operation. Furthermore, since a required deformation margin can be set for the overload detection device, damage to machines and instruments can be prevented. Moreover, due to the urging force of the plate urging means and the positioning action of the positioning and displacement means, there is an effect that after the overload is removed, the working state can be quickly returned to and the work can be resumed.

[Brief explanation of the drawing]

Fig. 1 is a vertical sectional view showing a first embodiment of the overload detection device for an industrial robot of the present invention, Fig. 2 is a perspective view of a welding robot equipped with the overload detection device for an industrial robot, and Fig. 3 is a perspective view of the welding robot equipped with the overload detection device for an industrial robot. Fig. 1 is a view taken along the - line arrow, Fig. 4 is a vertical sectional view showing the state when the overload detection device receives external force in the lateral direction, and Fig. 5A is a view showing the overload detection device in the rotational direction. Fig. 5B is a longitudinal sectional view showing the state when external force is applied, Fig. 5B is a sectional view showing the steel ball and positioning hole portion, Fig. 6 is a longitudinal sectional view showing the second embodiment of the present invention, Fig. 7 The figure is a longitudinal cross-sectional view showing the bellows portion taken out, and FIG. 8 is a side view showing an example of a conventional welding robot. 5... Welding robot, 20... Overload detection device, 21... Spot welding gun, 22... Upper fixed plate, 25... Fixed bracket, 26... Fixed plate, 28... Holding hole, 29... Movable Plate, 30...Positioning hole, 31...Steel ball, 32...
...Support bolt, 33...Compression coil spring,
35... Nut with locking mechanism, 38... Micro switch.

Claims (1)

[Scope of utility model registration request] In an overload detection device installed between the wrist end shaft 15 of an industrial robot and a working machine, a movable plate 29 is positioned with respect to a fixed plate 26, and when an overload is applied, the fixed plate 26 is
positioning and displacement means for displacing the relative positions of the fixed plate 26 and the movable plate 29; plate biasing means for biasing the fixed plate 26 and the movable plate 29 toward each other; and the movable plate 29. 1. An overload detection device for an industrial robot, comprising: displacement detection means for electrically detecting displacement of an industrial robot.