JPH0612254B2 - Centering method for holes - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a hole centripetal method for detecting the center position of a hole formed in an object to be detected.

(Prior Art) Conventionally, for example, in a car manufacturing line, when a fuel or engine lubricating oil is automatically injected into a completed car by a robot, a flange-shaped lid is provided around an injection nozzle held by the robot. To prevent blowback of fuel, etc. by providing a lid and injecting fuel, etc. with the lid part fitted in the injection hole on the automobile side and sealing the gap between the nozzle and the peripheral wall of the injection hole. There is. Then, in that case, if the nozzle is displaced from the center position of the injection hole even a little, it becomes difficult to surely fit the lid portion of the nozzle into the injection hole, and the effect of preventing blowback by the lid portion may not be obtained. Therefore, it is necessary to accurately detect the center position of the injection hole.

By the way, as a method of detecting the center position of the hole in this way, conventionally, the hole shape of the object to be detected is captured by a visual sensor and is projected as a TV image, and the center position of the hole in the TV image is electrically detected. An image processing method and a sensor method in which a plurality of sensors are provided and the position shift amount is determined based on the difference between the signals from the respective sensors to detect the center position of the hole are well known.

(Problems to be Solved by the Invention) However, in the former image processing method, since the image on the TV screen is electrically processed, the circuit configuration of the device becomes large and complicated, while the latter sensor The method has a problem that it requires a plurality of sensors.

Further, when the center position of the hole is detected by the optical system in this way, for example, under the conditions such as the above-mentioned automobile manufacturing line, disturbance light, excess or deficiency of illuminance, and malfunction due to environmental conditions (dust, oil, etc.) are likely to occur, There was a problem that the detection accuracy decreased.

The present invention has been made in view of these points, and its object is to focus on that the back pressure of the air discharged to the hole of the object to be detected changes according to each position of the hole, By detecting the center position of the hole based on the change in air back pressure,
The object is to enable the center position of the hole to be easily and accurately detected with a single sensor.

(Means for Solving the Problem) In order to achieve the above-mentioned object, in the solution means of the present invention, an air nozzle for ejecting air to a hole of an object to be detected is a surface perpendicular to the axis of the through hole of the object to be detected. First, relative movement is made so as to cross at least the range of the hole in the predetermined first axial direction in the vertical plane, and the minimum point position of the air back pressure in the movement range at that time is obtained.

Then, the air nozzle is relatively moved from the obtained minimum point position to the second axial direction orthogonal to the first axial direction at least across the range of the hole in the same manner as the movement in the first axial direction. Then, the minimum point position of the air back pressure in the moving range is detected as the center position of the hole.

(Operation) With the above configuration, in the present invention, when the air nozzle is first relatively moved in the first axial direction so as to cross at least the range of the hole, the air back pressure in the range of movement is the through hole of the object to be detected. The air back pressure rises because it is difficult for the discharge air to flow out smoothly in areas other than the holes, but the air back pressure rises smoothly in the area of the holes. And the air back pressure decreases greatly toward the center of the hole. Therefore, the minimum point position of the air back pressure in the movement range in the first axial direction should always be located on the straight line extending through the center position of the hole in the second axial direction orthogonal to the first axial direction. become.

Therefore, after this, the air nozzle is connected to the first
When the relative movement is made from the position of the air back pressure minimum point in the axial direction of at least so as to cross at least the range of the hole in the second axial direction, the air nozzle moves on a straight line passing through the center position of the hole. According to the principle of, the minimum point position of the air back pressure in the moving range is the center position of the hole.

In that case, the center position of the hole can be detected simply by sequentially moving the air nozzle in the plane perpendicular to the axis of the hole of the object to be detected in the two directions of the first and second axial directions. The air nozzle is sufficient, and only the minimum point position of the air back pressure needs to be detected, and the center position of the hole can be easily detected with an extremely simple structure.

(Example) Hereinafter, the Example of this invention is described.

FIG. 1 shows the configuration of a hole centripetal device used in an embodiment of the present invention, and 1 is an air nozzle attached to the arm tip of a robot (not shown) and moving in front of a circular hole W ₁ in an object W to be detected. The air nozzle 1 is connected to an air source 5 via an air passage 4 having an orifice 2 and a check valve 3, and the pressure air supplied from the air source 5 passes from the air nozzle 1 to the object W to be detected. It is discharged toward.

Reference numeral 6 is a pressure conversion that detects the back pressure P of the air discharged from the air nozzle 1 as the pressure inside the air passage 4 between the orifice 2 and the check valve 3 and outputs an output signal corresponding to the air back pressure P. The output signal of the pressure converter 6 is the minimum value thereof, that is, the minimum value P of the air back pressure P.
It is input to the minimum value storage 7 that constantly detects and stores _MIN . In addition, the pressure converter 6 and the minimum value memory 7
Output signals of the first to third comparators 8 to
It has been entered in 10. The first comparator 8 stores the minimum value of the air back pressure P detected by the pressure converter 6 in the memory 7
When P> P _{MIN which} is larger than the minimum value P _{MIN of the} air back pressure stored in, and when the air back pressure P is equal to the minimum value P _MIN , P = P _MIN , Further, the third comparator 10 outputs a Hi signal when the air back pressure P is smaller than the minimum value P _MIN and P <P _MIN , and the output signals of these comparators 8 to 10 control the operation of the robot. I / O interface 1 for robot in control position for
It is input to 1.

The output signal of the second comparator 9 is input to one input portion of the OR gate 12, the output signal of the OR gate 12 is input to one input portion of the AND gate 13, and the output signal of the AND gate 13 is the above. It is input to the other input section of the interface 11 and the OR gate 12. Further, the Hi signal is always input to the other input portion of the AND gate 13 from the interface 11, and the output signal of the AND gate 13 is self-held to the Hi signal in accordance with the output of the Hi signal from the second comparator 9. It is designed to do. The minimum value memory 7 and the AND gate 13 are reset by a one-shot pulse signal from the interface 11.

The method of the present invention for detecting the center position O of the hole W ₁ in the object W using the centripetal device configured as described above will be described.

First, as shown in FIG. 2, by controlling the robot, the air nozzle 1 for ejecting air is moved to the hole W _{1 of the} object W to be detected.
The robot is moved to an arbitrary start position S on the front side, and in that state, a one-shot pulse signal is issued from the robot I / O interface 11 to the minimum value storage 7 and the AND gate 13 to reset both, and then the above is controlled by the robot. In the plane perpendicular to the axis of the hole W ₁ from the start position S, the air nozzle 1 is first moved to a predetermined first plane in the vertical plane.
(In Figure 1 the direction perpendicular to the drawing sheet) axially moves across at least a range of hole W _1, the air of the rear P ₁ to be discharged toward the front of the detected object W from the air nozzle 1 _Is detected by the pressure converter 6, and the air back pressure P ₁ in the moving range of the air nozzle ₁ is the minimum value P _1MIN.
The position O ′ is obtained.

That is, when the air nozzle 1 is moved in the first axial direction, as shown in FIG. 2, when the air nozzle 1 is moving in the direction away from the center position O of the hole W ₁ , the air back pressure P ₁ increases gradually, the fact is detected by the first comparator 8 and a Hi signal is output from the first comparator 8 to the robot I / O interface 11, and the robot which receives this Hi signal outputs the air nozzle 1
Is moved in the direction opposite to the moving direction up to then.

On the other hand, in a state where the air nozzle 1 is moving toward the center position O side of the hole W ₁ , the air back pressure P ₁ gradually decreases. Therefore, this is detected by the third comparator 10 and the comparator is detected. 10 to interface 11
To the H signal from the third comparator 10.
While the i signal is being output, the robot continuously moves the air nozzle 1 in the same direction. When the air back pressure P ₁ reaches the minimum value P _1MIN at the position O ′ due to the movement of the air nozzle 1, the minimum value P _1MIN is stored and held in the minimum storage device 7, and thereafter, the air nozzle 1 is moved to the above position. Even if an attempt is made to move beyond O ', the moving direction of the air nozzle 1 is corrected to the opposite direction by the control described above. When the air back pressure P ₁ becomes equal to the minimum value P _1MIN stored in the minimum value storage device 7 in this way, the fact is detected by the second comparator 9 and the comparator 9
Outputs a Hi signal from the interface 11 to the AND gate 1 by the Hi signal from the second comparator 9.
3 self-holds the output of the Hi signal, and the robot that receives this holds the air nozzle 1 at the position O '. The minimum air back pressure point position O'obtained in this way is
It will always be located on the straight line 1 extending through the central position O ₁ of the hole W ₁ in the second axial direction (direction parallel to the paper surface in FIG. 1) orthogonal to the first axial direction.

Then, after the one-shot pulse signal is again issued to the minimum value storage unit 7 and the AND gate 13 to reset them, the robot controls the air nozzle 1 to move the air nozzle 1 to the minimum point position in the plane perpendicular to the axis of the hole W _1. From O'to the second axial direction orthogonal to the first axial direction, at least the hole W is formed in the same manner as above.
₁ is moved across the range of ₁ , and the minimum point position O at which the air back pressure P ₂ has the minimum value P _2MIN in the moving range is determined, and the minimum point position O is set as the center position of the hole W ₁ .

That is, the air nozzle 1 is moved from the minimum point position O ′ to the second position.
When the air nozzle 1 is moved in the axial direction, the air back pressure P ₂ is gradually increased in the state where the air nozzle 1 is moved in the direction away from the center position O of the hole W ₁ , similarly to the movement in the first axial direction. Therefore, it is detected by the first comparator 8 and the air nozzle 1 is moved in the direction opposite to the moving direction up to that point.

On the other hand, in a state where the air nozzle 1 is moving toward the center position O side of the hole W ₁ , the air back pressure P ₂ is gradually reduced, which is detected by the third comparator 10 and the air nozzle Continue moving 1 in the same direction. Then, the movement of the air nozzle 1 to the position O where the air back pressure P ₂ becomes the minimum value P _2MIN is determined by the second comparator 9
The air nozzle 1 is stopped at the position O by the output of the Hi signal from the second comparator 9. The minimum point position O of the air back pressure thus obtained is the center position of the hole W ₁ because the air nozzle 1 moves above the straight line l.

The center position O of the hole W ₁ detected by the above method is stored in the robot, and the robot is operated based on the stored center position O to perform various works on the hole W ₁ (for example, automatic fuel injection work for automobiles). Etc.).

Therefore, in this case, the air nozzles 1 for ejecting air are arranged in the first and second directions which are orthogonal to each other on the front side of the hole W _{1 of the} object W to be detected.
In order to detect the center position O of the hole W ₁ based on the back pressure of the discharge air at that time, only one air nozzle 1 is required as a sensor, and the output signal from that sensor is used. The circuit configuration for processing is also simple, and therefore the central position O of the hole W ₁ of the object to be detected W can be accurately and easily detected with a single sensor.

(Effect of the invention) As described above, according to the hole centripetal method of the present invention,
The minimum position of the air back pressure obtained at that time by moving the air nozzle that discharges air sequentially relative to each other in two directions perpendicular to the axis of the hole of the object to be detected so as to cross at least the range of the hole. Since the center of the hole is centered on the basis of, the central position of the hole of the object to be detected can be accurately and easily detected by using a single sensor like an air nozzle and with a simple structure.

[Brief description of drawings]

The drawings show an embodiment of the present invention, FIG. 1 is a block diagram of a centripetal device for holes, and FIG. 2 is an explanation showing characteristics of air back pressure change when the air nozzle moves in the first and second axial directions. It is a figure. 1 ...... air nozzle, 6 ...... pressure transducer, 7 ...... minimum value storage, W ...... object to be detected, _{W 1} ...... well, _P, P 1, _{P 2} ...
... Air back pressure, _P1MIN , _P2MIN ... Minimum value, O ...
… Center position.

Claims (1)

[Claims] 1. An air nozzle for ejecting air to a hole of an object to be detected, in a plane perpendicular to the axis of the hole, first so as to cross at least the range of the hole in the first axial direction in the vertical plane. Relative movement is performed to obtain the minimum point position of the air back pressure in the movement range, and then relative movement is performed from the minimum point position in the second axial direction orthogonal to the first axial direction so as to cross at least the range of the hole. Then, the centering method of the hole is characterized in that the position of the minimum point of the air back pressure in the moving range is detected as the center position of the hole.