JPH081364B2 - Gap detector - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a gap detecting device, and more particularly to a gap detecting device suitable for guiding a welding heat source for welding a butt portion of a cylindrical object to the butt portion. .

[Prior Art] When performing butt welding of metal or the like, a gap detection device is used to detect the gap at the butt portion, and the welding heat source is guided to the butt portion with high accuracy based on the detection result. Is being done. FIG. 3 shows a conventional gap detecting device. In the gap detecting device main body 1, a line beam 4 for irradiating a pipe 2 which is an object to be measured with a light beam 3 and a regular reflection light 5 from the pipe 2. And a light receiver 6 for receiving the light. This pipe 2 has an abutting portion forming a gap 7 as shown in FIG.
Irradiates obliquely so as to straddle the gap 7 while vibrating the linear luminous flux 3 larger than the gap 7. The irradiation light beam 3 is specularly reflected on the outer peripheral surfaces of the pipes at both ends of the gap 7, and the specularly reflected light 5 is incident on the light receiver 6. The specular reflection light 5 is divided by the gap 7 and enters the photodetector 6 as specular reflection lights 5A and 5B. FIG. 5 shows spots 5a and 5b of specular reflection lights 5A and 5B incident on the light receiver 6. The gap detection device detects the gap between the reflected light spot 5a and the reflected light spot 5b of the light receiver 6 as a gap 7. Based on this detection result, the welding heat source can be accurately guided to weld the butt portion.

[Problems to be Solved by the Invention] However, in the conventional gap detection device, a part of the irradiation light flux 3 passes through the gap 7, is specularly reflected by the inner peripheral surface 8 of the pipe 2, and is reflected by the light receiver 6 as specularly reflected light 9. Incident. Therefore, as shown in FIG. 5, a reflected light spot 9a is formed on the light receiver 6 in addition to the regular reflected light spot 5a and the reflected light spot 5b, and the reflected light spot 9a is formed by the reflected light spot 9a. It has a significant adverse effect on the detection results. Therefore, the conventional gap detection device has a problem that it is not possible to perform highly accurate gap detection for an object to be measured having a shape in which the irradiation light that has passed through the gap is reflected by the surface behind the gap and enters the light receiver.

As a solution to this problem, an electric soft filter 10 as shown in FIG. 5 is applied to the output of the light receiver 6 to weaken the electric signal relating to the reflected light spot 9a and remove the adverse effect of this reflected light spot 9a. There are possible ways to do this. However, this method using the electric soft filter cannot exert a sufficient effect when the intensity of the reflected light spot 9a is large, and highly accurate gap detection is impossible.

Therefore, an object of the present invention is to provide a gap detection device capable of detecting a gap with high accuracy even for an object to be measured having a shape in which irradiation light passing through the gap is reflected by a surface behind the gap and is incident on a light receiver. To provide.

[Means for Solving the Problem] In order to achieve this object, a gap detecting device of the present invention detects a gap of a cylindrical pipe formed by butt welding a gap extending in an axial direction. A device, which is arranged at a position facing the gap, extends linearly in the width direction of the gap so as to straddle the gap, and is linear along the direction in which the gap extends. A light source that irradiates from above, a light receiver that receives the reflected light beam in which the light beam is regularly reflected by the outer peripheral surface or the inner peripheral surface of the pipe, and is disposed on the front surface of the light receiver, and among the reflected light beam,
Accept the reflected light beam that is specularly reflected on the outer peripheral surface of the pipe,
Of the slit portion extending in the width direction of the gap, and the reflected light flux, the light flux entering the pipe from the gap is reflected on the inner peripheral surface of the pipe, passes through the gap again, and goes out of the pipe. A shielding plate having a shielding portion that shields the reflected light flux that reaches it, and the distance in the axial direction of the pipe between the emission portion from which the light flux is emitted from this gap detection device and the slit portion is C, and the emission portion is The distance in the axial direction of the pipe between
And E is the distance between the injection portion and the pipe outer peripheral surface and the distance between the slit portion or the shielding portion and the pipe outer peripheral surface, and F is the value obtained by subtracting the wall thickness dimension from the outer diameter dimension of the pipe. , The incident angle of the light beam emitted from the emission unit with respect to the outer peripheral surface of the pipe is θ
Then, the slit portion is arranged at a position satisfying the relation of C = 2Etan θ, and D = 2 (E + F) ta
It is characterized in that the shielding portion is arranged so as to cover a portion satisfying the relationship of nθ.

[Operation] Part of the light beam emitted by the light source is specularly reflected on the outer peripheral surface of the pipe, while the remaining part of the light beam enters the pipe through the gap and is specularly reflected on the inner peripheral surface of the pipe. .

At this time, the reflected light beam specularly reflected on the inner peripheral surface of the pipe is narrowed down by the gap when passing through the gap, and the irregular reflection component is cut. Therefore, of the luminous fluxes emitted by the light source, the geometrical route for the reflected luminous flux that passes through the gap and enters the pipe, and is specularly reflected by the inner peripheral surface of the pipe and passes through the gap again is calculated. By disposing the shielding portion on the path, the reflected light beam specularly reflected on the inner peripheral surface of the pipe can be reliably shielded and separated from the reflected light beam specularly reflected on the outer peripheral surface of the pipe.

On the other hand, since the outer peripheral surface of the pipe is a cylindrical curved surface, among the light fluxes radiated to the outer peripheral surface of the pipe, the reflected light flux specularly reflected at the apex of the outer peripheral surface of the pipe, that is, in the vicinity of the gap, is along the direction in which the gap extends. And proceed. On the other hand, the reflected light beam that is specularly reflected at a position apart from the gap in the width direction of the gap travels away from the width direction of the gap. With this, a path for the reflected light beam that is regularly reflected at the apex portion of the outer peripheral surface of the pipe is geometrically determined, and a slit portion that extends in the width direction of the gap is formed on the path to receive the reflected light beam. The reflected light beam specularly reflected in the vicinity of the gap can be separated from the reflected light beam specularly reflected at a position away from the gap and can be received by the photodetector.

Therefore, the light receiver can recognize the gap portion as a brighter image as the inner portion of the gap is darker and the portion closer to the gap on the outer peripheral surface of the pipe is brighter, and by appropriately processing this image, The boundary between the outer peripheral surface of the pipe and the gap can be clearly identified, and the position of the gap can be detected with high accuracy.

[Embodiment] An embodiment of the gap detecting device according to the present invention will be described below with reference to FIGS. 1 and 2 in which the same parts as those in FIGS. 2 to 4 are denoted by the same reference numerals. .

In FIG. 1 and FIG. 2, the gap detection device main body 1
A line light source 4 such as a laser diode and a light receiver 6 such as a CCD sensor are attached to each of them. A cylindrical lens 11 is arranged in front of the linear light source 4, and the cylindrical lens 11 stretches the light flux 3 from the linear light source 4 in a direction perpendicular to the paper surface to form a linear light flux. The size, that is, the diameter of this linear luminous flux is selected to be larger than the gap 7 of the pipe 2 as shown in FIG.

A shielding plate 12 is arranged on the front surface of the light receiver 6, and the shielding plate 12
Reference numeral 12 has a slit 12a that transmits only specular reflection light 5A and 5B from the outer peripheral surface of the pipe 2. The size and position of this slit 12a are determined as follows. That is, the irradiation light flux 3
Is a position emitted from the gap device main body 1 is P1, a position where specular reflection light 5 from the outer peripheral surface of the pipe 2 is incident on the gap device main body 1 is P2, and a regular reflection light 9 from the inner peripheral surface 8 of the pipe 2 is P3 is the position where is incident on the gap device body 1,
Let C be the distance between positions P1 and P2, and D be the distance between positions P1 and P3.
And Further, the distance between the lower surface of the gap detection device main body 1 and the upper surface of the pipe 2 is E, and the distance from the upper surface of the pipe 2 to the inner peripheral surface of the pipe to which it faces (that is, the outer diameter of the pipe 2 minus the pipe wall thickness). Value) as F. The incident angle of the irradiation light flux 3 on the outer peripheral surface and the inner peripheral surface 8 of the pipe 2 is θ. Then, the distances C and D can be expressed by the following equations.

C = 2Etanθ (1) D = 2 (E + F) tanθ (2) Therefore, if the values E, F, and θ are specified, the distances C and D can be calculated from the above equations (1) and (2). Can be asked. The shielding plate 12 is arranged so that the slit 12a is located at the position P2 calculated in this way and shields other areas including the position P3.

 Next, the operation of this embodiment will be described.

The luminous flux 3 emitted from the linear light source 4 is a cylindrical lens 11
Is converted into a linear light flux by the light source, emitted from the gap device main body 1 at the position P1, and is incident on the outer peripheral surface of the pipe at an incident angle θ so as to straddle the gap 7. Of the irradiation light flux 3 incident on the outer peripheral surface of the pipe, the apex portion of the pipe, that is, the portion incident on the position near the gap is specularly reflected in the direction along the paper surface shown in FIG. 1, and at the position P2, the slit 12a of the shielding plate 12 is formed.
And then enters the light receiver 6. On the other hand, the portion of the irradiation light flux 3 incident on the outer peripheral surface of the pipe, which is incident at a position apart from the gap 7 in the width direction, is specularly reflected on the outer peripheral surface of the cylindrical pipe, and the paper surface shown in FIG. With respect to the diagonal direction, it goes away from the slit 12a. On the other hand, a part of the irradiation light flux 3 passes through the gap 7 and enters the inner peripheral surface 8 of the pipe 2 at an incident angle θ, where it is specularly reflected and is specularly reflected light 9 as a light receiver 6
However, the light is blocked by the shield plate 12 and blocked from entering the light receiver 6. That is, the gap detecting device of the present invention not only reliably separates the reflected light beam specularly reflected on the outer peripheral surface of the pipe 2 and the reflected light beam specularly reflected on the inner peripheral surface 8 of the pipe 2, but also the outer peripheral surface of the pipe 2. Of the reflected light flux specularly reflected above, the reflected light flux specularly reflected in the vicinity of the gap 7,
The reflected light beam specularly reflected at a position away from the gap 7 is reliably separated.

Therefore, the light receiver 6 can recognize the portion of the gap 7 as a brighter image as the inner portion of the gap 7 is darker and the portion closer to the gap 7 on the outer peripheral surface of the pipe is brighter. By the processing, the boundary portion between the outer peripheral surface of the pipe and the gap 7 can be clearly identified, and the position of the gap 7 can be detected with high accuracy.

EFFECTS OF THE INVENTION As is clear from the above description, the gap detecting device of the present invention is a device for detecting the gap position of a cylindrical pipe formed by butt welding a gap extending in the axial direction. , The light flux emitted from the light source is surely separated from the reflected light flux reflected on the outer peripheral surface of the pipe and the reflected light flux reflected on the inner peripheral surface of the pipe, and is reflected near the gap among the reflected light flux reflected on the outer peripheral surface of the pipe. The reflected light flux and the reflected light flux reflected at a position apart from the gap are reliably separated. As a result, the light receiver can recognize the gap portion as a brighter image as the inner portion of the gap is darker and the portion closer to the gap on the outer peripheral surface of the pipe is brighter.
By appropriately processing this image, the boundary portion between the outer peripheral surface of the pipe and the gap can be clearly identified, and the position of the gap can be detected with high accuracy.

[Brief description of drawings]

FIG. 1 is a schematic view showing an embodiment of the gap detecting device according to the present invention, FIG. 2 is a sectional view showing a cross section of the pipe of FIG. 1, and FIG. 3 is a conventional gap detecting device. Schematic drawing, FIG. 4 is a cross-sectional view showing a cross section of the pipe of FIG. 3,
FIG. 5 is an explanatory diagram showing spots of light beams incident on a light receiver of a conventional gap detection device. 2 ... Object to be measured, 3 ... Irradiation luminous flux, 4 ... Light source, 4, 11
...... Irradiation means, 5 ...... Regular reflection light, 6 …… Light receiving means, 7 ・ ・ ・
… Gap, 8 …… Rear surface, 9 …… Regular reflection light, 12 …… Shield plate.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Sadaya Sekiya 1-1-1, Shibaura, Minato-ku, Tokyo Inside Toshiba Headquarters Office (56) References JP-A-61-27178 (JP, A) JP-A-SHO 61-186803 (JP, A)

Claims (1)

[Claims] 1. A gap detecting device for detecting the gap of a cylindrical pipe formed by butt-welding a gap extending in an axial direction, the gap detecting device being disposed at a position facing the gap, and having a width of the gap. A light source that irradiates a linear light beam that extends in the direction over the gap and that is longer than the width of the gap from diagonally above along the direction in which the gap extends, and the light beam on the outer peripheral surface or the inner peripheral surface of the pipe. A light receiver for receiving the reflected light beam that is specularly reflected, and a slit portion that is disposed on the front surface of the light receiver and that receives the reflected light beam that is specularly reflected on the outer peripheral surface of the pipe among the reflected light beam and that extends in the width direction of the gap. , And of the reflected light flux, the light flux entering the pipe through the gap is reflected by the inner peripheral surface of the pipe and passes through the gap again. And a shielding plate having a shielding portion that shields the reflected light flux that reaches the outside of the pipe, and the distance between the emission portion that emits the light flux from the gap detection device and the slit portion in the axial direction of the pipe is C. And the distance in the axial direction of the pipe between the injection part and the shielding part is D, the distance of the injection part to the pipe outer peripheral surface, and the distance of the slit part or the shielding part to the pipe outer peripheral surface. Let E be each, and let F be the value obtained by subtracting the wall thickness dimension from the outer diameter dimension of the pipe, and let θ be the incident angle of the light flux emitted from the emission portion with respect to the pipe outer peripheral surface, then C = 2Etan θ The slit portion is arranged at a position satisfying the relationship, and D = 2 (E +
F) A gap detecting device, wherein the shielding portion is arranged so as to cover a portion satisfying the relationship of tan θ.