JPH1044086A - Over-travel detection device of industrial robot - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a limit switch of an over-travel detection device from stepping off a dog without limiting the rotatable scope of a rotation part of an industrial robot to less than 360 deg.. SOLUTION: A limit switch 11 is fixed and set on a swinging barrel 10, and a circular shaped guide 14 is provided for slidably holding the dog 13 on the side of the base 12 thereby regulating a movement locus and the movement amount of the dog 13. By setting the length of the guide 14 to two or more times the length of the dog 13, the normal rotatable scope of the swinging barrel 10 can be set to 360 deg. or more, and the dog 13 itself can be constituted in a long configuration thereby the limit switch 11 can be prevented from stepping off the dog 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in an overtravel detecting device for an industrial robot.

[0002]

2. Description of the Related Art An overtravel detecting device for an industrial robot is known in which a limit switch and a dog are provided on a rotating portion and a fixed portion of a robot to detect overtravel of the rotating portion. FIG. 4 shows a conventional example of this kind of overtravel detector.

FIG. 4 shows an example in which an overtravel detecting device is provided between a base 1 of an industrial robot and a revolving torso 2 which rotates with respect to the base 1. In this example, FIG. A limit switch 4 is provided on the side of the base 1 which is a fixed portion, and a dog 3 is provided on the side of the revolving drum 2 which is a rotating portion. As shown in FIG. 4, the dog 3 formed in a polygonal shape is mounted so as to pivotably support the vicinity of the apex of the dog 3 with respect to the revolving drum 2 via a bolt 5, and is fixed to the right and left thereof. The swing range is regulated by the stoppers 6 and 7.

As shown in FIG. 4, when the dog 3 contacts the stopper 6 at the clockwise swing limit, the switch contact surface 3a of the dog 3 is substantially parallel to the surface 4a of the limit switch 4, and As is apparent from FIG. 4, when the dog 3 contacts the stopper 7 at the swinging limit in the counterclockwise direction, the switch contact surface 3b of the dog 3 becomes the surface 4 of the limit switch 4.
a, the right end position of the switch contact surface 3a under the former condition and the left end position of the switch contact surface 3b under the latter condition are located near the virtual point P on the base 1. It is designed to be.

If the base 1 is formed by a complete cylinder, the imaginary point P is located on an extension of the radius of the revolving drum 2 passing through the bolt 5, and the probe with a roller of the limit switch 4 is provided. When the tip of 4b is pushed to the position P, the limit switch 4 is activated.

That is, the limit switch 4 is a push-type normally-open contact type limit switch that operates only when the probe 4b which is protruded by a spring is pressed.

FIG. 4 shows a situation in which the revolving drum 2 is rotating counterclockwise and the dog 3 is approaching the limit switch 4. The probe 4b of the limit switch 4 first moves the dog 3 in the first stage. Abuts on the right abutment surface 3c, and regardless of the posture of the dog 3 at the time of the abutment, pushes it back and swings to the clockwise swing limit. And the revolving barrel 2
Is rotated counterclockwise, the probe 4b is pushed by the component of the vertical reaction force received from the right contact surface 3c of the dog 3, the limit switch 4 is operated, and the probe 4b passes through the switch contact surface 3a of the dog 3. Until the limit switch 4 is turned on, the ON state of the limit switch 4 is maintained.

That is, in this example, the state when the probe 4b of the limit switch 4 provided on the base 1 overlaps the position P on the revolving drum 2 is defined as the limit of the counterclockwise rotation of the revolving drum 2. The counterclockwise rotation of the revolving drum 2 exceeding this is treated as overtravel.

Also, the limit of the clockwise rotation of the swivel cylinder 2 is as follows.
As above, limit switch 4 provided on base 1
Is set as a state when the probe 4b is overlapped on the position P on the base 1, and the normal rotatable range of the rotating body 2 is 360 ° (one rotation).

However, when the clockwise rotation reaches the limit, the probe 4 of the limit switch 4
b first abuts against the left abutment surface 3d of the dog 3 in the first stage, and the probe 4b pushes back the dog 3 to oscillate to the counterclockwise swing limit, and the left abutment surface of the dog 3 During the period from when the probe 3b pushes the probe 4b to when the probe 4b passes through the switch contact surface 3b of the dog 3, the limit switch 4
Is maintained in the ON state.

The ON signal of the limit switch 4 serving as an overtravel signal is generated when the tip of the probe 4b overlaps the position P on the base 1, that is, the tip of the probe 4b is switched from the right contact surface 3c of the dog 3 to the switch. The stage of shifting to the contact surface 3a (when the revolving drum 2 rotates counterclockwise) or the stage of shifting the tip of the probe 4b from the left contact surface 3d of the dog 3 to the switch contact surface 3b. (When the turning cylinder 2 rotates clockwise), the signal is immediately output. However, even if the rotation of the turning cylinder 2 is braked immediately based on this signal, the motor, the driving mechanism, and the
Due to its own inertia, the turning cylinder 2 does not stop immediately, and a certain degree of coasting occurs.

The reason why the switch 3 is provided with the switch contact surface 3a and the switch contact surface 3b to keep the ON state of the limit switch 4 is to keep outputting the overtravel signal even during the coasting period. The tip of the probe 4b is located at the left end of the switch contact surface 3a of the dog 3 or the switch contact surface 3
If the turning cylinder 2 coasts until it deviates from the right end of b,
Various problems occur.

For example, when the tip of the probe 4b coasts beyond the left end of the switch contact surface 3a or the right end of the switch contact surface 3b, the revolving drum 2 is directly reversed to return to a normal position. Again, dog 3 is probe 4b
, The overtravel signal is output, and in order to prevent this, the dog 3 must be once removed to return the revolving drum 2 to a normal position.

Of course, if the revolving drum 2 is provided with a structure that can rotate any number of times, it is not necessary to provide an overtravel detecting device as long as one rotation is allowed. Actually, since various cables are connected to the swing drum 2, it is necessary to suppress the rotation of the swing drum 2 to one rotation (around 360 °) in order to prevent entanglement. It is not possible to omit mounting itself.

Therefore, as long as the overtravel detecting device is provided, the dog 3 can be used even if the turning cylinder 2 coasts to some extent.
It is desirable to design the switch contact surfaces 3a, 3b as long as possible so that the switch contact surfaces 3a, 3b do not step off the probe 4b. However, at least in the configuration shown in FIG. There is a problem that the size of the dog 3, which is a rocking piece, becomes extremely large with the extension of the surfaces 3a, 3b, and it is difficult to actually realize the size.

It is also conceivable to provide a long arc-shaped dog 8 (indicated by a broken line) or the like instead of the dog 3 along the outer peripheral portion of the revolving drum 2. There is a problem that the rotatable range is always limited to less than 360 °. In other words, if the length of the arcuate dog 8 is shortened, the ON state of the limit switch 4 cannot be maintained in response to coasting due to overtravel, and the length of the arcuate dog 8 is reduced. If the length is increased, the rotatable range of the turning drum 2 is greatly limited.

[0017]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned disadvantages of the prior art and to prevent a dog from stepping on a limit switch even when a large coasting due to overtravel occurs in a rotating portion of a robot. It is another object of the present invention to provide an overtravel detecting device for an industrial robot, which can maintain the rotatable range of the rotating portion at 360 ° or more.

[0018]

According to the present invention, a limit switch is provided on one of a rotating portion and a fixed portion of a robot, and a dog is provided on the other, which is engaged with and disengaged from the limit switch. An industrial robot overtravel detection device configured to detect overtravel of the rotating unit, wherein the overtravel amount is equal to or longer than a coasting amount generated from outputting a stop command to the rotating unit to stopping the rotating unit. A dog having a height, a limit switch is operated when a certain force or more acts between the limit switch and the dog, the dog or the limit switch is slidably supported, and The object is achieved by a configuration in which a guide for regulating the sliding amount is provided on the movement locus of the rotating section. It was.

Further, as means for maintaining the engagement state between the limit switch and the dog, a guide slidably supporting the dog or the limit switch is provided in an arc shape along the movement locus of the rotating portion. And a configuration in which the dog is provided with a width sufficient to cover a part of the movement trajectory, and the guide is linearly arranged in a tangent direction of the movement trajectory.

Further, by providing a stopper between the dog or the limit switch and the guide, the function of the overtravel detecting device can be maintained regardless of the installation direction of the robot, that is, the direction of action of gravity. .

[0021]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a conceptual diagram schematically showing the configuration of an overtravel detection device 9 according to an embodiment to which the present invention is applied. In FIG. 1A, the turning of an industrial robot equipped with the overtravel detection device 9 is illustrated. It shows a perspective view of the periphery of the torso base when viewed from above,
FIG. 1B shows a state in which the turning trunk base of the industrial robot to which the overtravel detecting device 9 is mounted is viewed from the side. In addition, the code | symbol O in FIG.1 (a) is the rotation center of the turning drum 10. FIG.

As shown in FIGS. 1 (a) and 1 (b),
In this embodiment, a limit switch 11 is provided on a side of a revolving drum 10 which is a rotating part of an industrial robot, and a dog 13 and a guide 14 are provided on a side of a base 12 which is a fixed part. In short, the limit switch 11 is fixedly provided on the side of the rotating body 10 which is a rotating portion, and the guide 14 in an arc shape along the movement locus S of the limit switch 11 is provided on the side of the base 12 which is a fixed portion, so that The dog 13 having the fitting portion 13a is fitted inside the groove 14a of the guide 14 so as to be slidable, and is slidably moved along the guide 14 by stoppers 15, 16 fixed to both ends of the guide 14. The sliding amount of the dog 13 is regulated.

Therefore, the stoppers 15, 16 are also substantially a part of the guide 14 and the retaining means, and the guide 1
The four and stoppers 15 and 16 are fixed on the base 12 at four corners or at both ends with bolts.

The dog 13 has an inverted T-shaped cross section as shown in FIG. 1 (b).
Since it is necessary to slide smoothly along 4a, its planar shape is formed in an arc shape as shown in FIG.

Also, the limit switch 11 is
Stay 17 fixed to the flange portion of No. 0 via bolts
The probe 11b is fixed to the tip of the device with the probe 11b facing downward. The limit switch 11 is a push-type normally open contact type limit switch that operates only when a probe 11b with a roller that is protruded by a spring and is protruded is pressed.

As shown in FIG. 1B, the probe 11b
Is the revolving barrel 1 projecting below the upper surface of the dog 13.
0, so that the probe 11b
With the rotation of 0, the dog 1
3, the tip of the probe 11b interferes with the end face 13b or 13c of the dog 13 (depending on the direction of rotation of the turning drum 10). Therefore, if the revolving drum 10 is rotated as it is, the probe 11b is moved to the end faces 13b, 13
The dog 13 can be slid clockwise or counterclockwise in FIG.

However, when this sliding operation reaches the limit, the other end faces 13c and 13b of the dog 13 are
15, the sliding movement of the dog 13 becomes impossible, and the probe 11 b rides on the dog 13.
When b is pushed in, the normally open contact of the limit switch 11 is closed, and an overtravel signal is output.

Although the rollers of the probe 11b are not damaged when the probe 11b rides on the dog 13, chamfered slopes are formed at the upper end portions of the end faces 13b and 13c of the dog 13, but they are projected in the protruding direction by a spring. Is adjusted so that the horizontal component of force applied to the slope by the roller of the probe 11b urged by the probe 11b is greater than the frictional force between the dog 13 and the guide 14. The dog 13 can be slid by a horizontal component force acting on the slope as long as the dog 13 does not come into contact with the dog.

The entire length (length in the circumferential direction) of the dog 13 is set to a certain margin so that the probe 11b does not step on the dog 13 even if the turning drum 10 coasts after the detection of the overtravel signal. And is configured to be longer than the coasting amount of the limit switch 11.

In this embodiment, the turning cylinder 1 is moved from the reference position.
Since the rotation allowable range of 0 is defined as 360 ° (one rotation), the length of the groove 14a in the guide 14 is required to be exactly twice the length of the dog 13, and as a result, the length of the dog 13 is reduced. The sliding stroke becomes equal.

FIG. 3 is an operation principle diagram showing the relationship between the rotational position of the turning cylinder 10 and the operation state of the limit switch 11 based on the relationship between the guide 14 and the dog 13 designed according to such a situation. . The above-mentioned reference position is shown in FIG.
The rotational position of the turning drum 10 shown in FIG.
In contrast, 360 ° (1
Rotation).

First, in the state shown in FIG.
3 comes into close contact with the stopper 15 and the probe 11
b is slightly outside clockwise (left side) from the end face 13c of the dog 13, so that the limit switch 11 is turned off.
And no overtravel signal is output.
This is the reference position of the revolving drum 10 and the rotation limit in the counterclockwise direction. Note that the term "rotation limit" does not include the amount of coasting.

Since there is no interference with the probe 11b even if the turning body 10 is rotated clockwise from this state, the OFF state of the limit switch 11 is kept at least until the probe 11b comes into contact with the dog 13 again. Will be maintained. Then, when the probe 11b encounters the dog 13 again by the clockwise rotation of the revolving drum 10, first, FIG.
As shown in (b), the end surface 13b of the dog 13 contacts the end surface 13b. In this state, there is a large gap between the other end surface 13c of the dog 13 and the stopper 16, so that the turning cylinder 10
Can rotate clockwise while pushing and sliding the dog 13 with the probe 11b.

Finally, when the end face 13c of the dog 13 contacts the stopper 16 as shown in FIG. 3C, the dog 13 cannot slide, and the probe 11b is
And the limit switch 11 is closed, and an overtravel signal is output. As already mentioned,
In this embodiment, since the length of the groove 14a in the guide 14 is just twice the length of the dog 13, as is clear from the comparison between FIG. 3A and FIG. When the motor rotates just 360 degrees from the state shown in FIG. 3A, the limit switch 11 is turned on and an overtravel signal is output.

Even if the revolving drum 10 is braked immediately based on the overtravel signal, the revolving drum 1 actually has an inertia due to the motor, the driving mechanism and the revolving drum 10 itself.
The rotation of 0 does not stop easily, and, for example, coasting of the turning drum 10 as shown in FIG. 3D occurs. In this embodiment, the dog 13 is configured to be longer in consideration of the coasting amount and the margin. As a result, the probe 11b does not step on the dog 13.

If the purpose is to prevent only stepping off due to coasting, the dog 13 may be fixed directly on the base 12, but if so, the dog 1
The normal rotatable angle of the turning cylinder 10 is 3 depending on the length of 3.
There is a problem that the angle is limited to less than 60 °. For example, assuming that the dog 13 is directly fixed to the base 12 in the example of FIG.
It is limited to the section from the state of FIG. 3A to the state of FIG. 3B, and can never reach 360 °. Also, if the dog 13 is directly fixed on the base 12 and the rotatable angle of the revolving drum 12 is to be as close as possible to 360 °, there is no other way than to reduce the length of the dog 13. However, this leads to a problem that the limit switch 11 steps off the dog 13 due to coasting.

In the case of this embodiment, even if the length of the dog 13 itself is designed to be considerably long, if the length of the groove 14a of the guide 14 is twice as long as the length of the dog 13, the turning cylinder must be formed. 10 can be rotated 360 ° in a normal state, so that the dog 13 can be prevented from being depressed and the revolving drum 10 can be rotated 360 °.
Rotation can be achieved simultaneously.

Although there is a limit, it is also possible to widen the rotatable range of the revolving drum 10 to 360 ° or more. In this case, as shown in FIGS. The length of the groove 14 a of the fourteen may be configured to be larger than twice the length of the dog 13.

The dog 13 is provided with a fitting portion 13a for preventing the dog 13 from coming off, and the stoppers 15 and 16 for preventing the dog 13 from coming off are also provided on the guide 14 side.
In addition to the base 12 and the revolving torso 10 in which the mounting direction of the bottom of the dog 13 is horizontal, for example, for a rotating part such that the bottom of the dog 13 must be mounted upright such as a U-axis. Also, exactly the same configuration can be applied to this.

Further, the shape of the dog and the guide need not necessarily be arc-shaped, and a linear dog 13 'and a guide 14' may be used as in the overtravel detecting device 18 shown in the embodiment of FIG. It is possible. When the linear guide 14 'is used, as shown in FIG.
4 'will be provided. In this case, depending on where the linear dog 13' is located on the linear groove 14 ',
The position where the probe 11 hits the end face 13'b or the end face 13'c is different. Therefore, the probe 11b has the end face 1
The width W of the dog 13 'must be adjusted to prevent the step 3'b, the end surface 13'c and the upper surface of the dog 13' from being depressed.
It is necessary to make it wider than the embodiment. Of course,
In terms of the processing required for manufacturing, this one is much easier.

As shown in FIG. 2B, a limit switch 11 is provided on the side of the base 12 which is a fixed portion.
A limit switch 11 is provided on the side of the revolving barrel 10 which is a movable part.
The guide 13 'may be provided along the relative movement trajectory S, and the dog 13' may be attached. The operation and effect are the same as those in the above-described embodiment.

Of course, even if a limit switch, a dog and a guide mounting method as shown in FIG. 2B are applied to a configuration using an arcuate guide or dog as shown in FIG. 1A. Also, as shown in FIG. 2A, a configuration using a linear guide or dog is shown in FIG.
Alternatively, a method of mounting a limit switch, a dog and a guide as shown in FIG.

In the embodiments described above, in any case, the limit switch is fixed and the dog is slid, but the dog is fixed and the limit switch is moved with respect to the guide. It is also possible to apply a configuration that can be slidably attached.

[0044]

According to the present invention, even if the length of the dog for operating the limit switch is increased, the rotatable range of the rotating portion of the industrial robot is not restricted by the lengthening of the dog. It is possible to simultaneously prevent the dog from being depressed due to coasting and to achieve a normal rotation of the rotating portion of 360 ° or more.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing an outline of a configuration of an overtravel detection device according to an embodiment to which the present invention is applied.

FIG. 2 is a conceptual diagram schematically showing a configuration of an overtravel detecting device according to another embodiment to which the present invention is applied.

FIG. 3 is a diagram illustrating the operation principle of the overtravel detection device of each embodiment.

FIG. 4 is a diagram showing a conventional example of an overtravel detection device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Base 2 Revolving drum 3 Dog 3a Switch contact surface 3b Switch contact surface 3c Right contact surface 3d Left contact surface 4 Limit switch 4a One surface of limit switch 4b Probe 5 Bolt 6 Stopper 7 Stopper 8 Stopper 8 Dog 9 Overtravel detector DESCRIPTION OF SYMBOLS 10 Revolving body 11 Limit switch 11b Probe 12 Base 13 Dog 13 'Dog 13a Fitting part 13b End face 13'b End face 13c End face 13'c End face 14 Guide 14' Guide 14a Groove 14'a Groove 15 Stopper 16 Stopper 17 Stay 18 Over Travel detector O Rotation center of rotation body S Movement locus

Claims (4)

[Claims] 1. A limit switch is provided on one of a rotating part and a fixed part of a robot, and a dog is provided on the other, which is engaged with and disengaged from the limit switch, and an overtravel of the rotating part is detected by operating the limit switch. An overtravel detection device for an industrial robot, wherein a dog having a length equal to or longer than a coasting amount generated from outputting a stop command to the rotating unit to stopping the rotating unit is provided, The limit switch is configured to operate when a force equal to or more than a predetermined value acts between the limit switch and the dog, and the guide that slidably supports the dog or the limit switch and regulates the sliding amount is provided. An overtravel detection device for an industrial robot, which is provided on a movement locus of a rotating unit. 2. The overtravel detecting device for an industrial robot according to claim 1, wherein the guide is provided in an arc shape along a movement trajectory of the rotating section. 3. The industrial robot according to claim 1, wherein the dog has a width sufficient to cover a part of the movement trajectory, and the guide is formed linearly in a tangent direction of the movement trajectory. Travel detector. 4. The overtravel detecting device for an industrial robot according to claim 1, wherein a stopper is provided between the dog or the limit switch and the guide.