JP2001276974A - Method for detecting groove width and dislocation quantity - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for detecting groove width and dislocation quantity which has a combination of a roller having an ability to follow a groove and a sensor to detect distance to obtain information on a groove easily and correctly. SOLUTION: In butt welding, the roller which has tapered shape with definite angle at outer circumference, is arranged so as to enter into a groove 5 in front of welding arc 11. Laser sensor 2a, 2b which measure respective distance corresponding to the surface of right-and-left welded members, are fixed on both right-and-left sides. An amount of fluctuation of the groove is detected from the product found by the sum of a quantity of right-and-left displacement distance (ΔL1+ΔL2) and tanθ (θ: inclined angle in one side of the roller), dislocation quantity detected from the difference between right-and-left displacement distance (ΔL2-ΔL1).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting a groove width and a misalignment amount in butt welding, and particularly to a butt welding of a thick plate of a large structure in which the groove width is largely fluctuated and misalignment is likely to occur. Related to the technology applied to

[0002]

2. Description of the Related Art Methods of detecting gaps and misalignments in a groove portion are roughly classified into a contact type and a non-contact type. The former uses a roller or a probe-type contact sensor, etc.
The latter is a method using an image sensor, a laser sensor, or the like.

A method using a contact-type sensor is, for example, as disclosed in Japanese Patent Application Laid-Open No. 57-106476.
In this method, two large and small spherical contacts are inserted into and brought into contact with a groove, a groove shape is estimated from the positions of these spheres, and it is detected that the groove width is within an allowable dimension.

However, this method does not detect the width of a groove during welding, and is applicable only to a Y-shaped or V-shaped groove. It cannot be done.

On the other hand, the non-contact image sensor and the image processing method (light cutting method) using a slit laser require a great deal of labor to develop detection software. Correction is required when the effect is large or the depth of focus of the camera fluctuates. Also,
The light cutting method has problems in that it is difficult to take measures against noise of arc light during welding, and there are many restrictions on the width of slit light, laser light intensity, and the like.

Further, in the laser sensor rocking method in which the laser beam is rocked in the groove width direction, when the groove shape changes within the rocking cycle, the actual groove width and the detected groove width are changed. In some cases, it may be difficult to detect the groove root due to multiple reflections of the laser beam depending on the groove angle. Further, the laser scan sensor system that scans the spot laser in the groove width direction has problems in that it is difficult to select an arc light interference filter and that the price of the sensor is high.

[0007]

As described above, the prior art has many problems as described above, and at present there is no inexpensive means. Particularly in butt welding of large structures such as shipbuilding and bridges, the thickness is often large, so that the groove width may greatly change during welding and misalignment may occur. There has been a demand for the development of a simple and inexpensive technique for detecting a groove width and misalignment that can sufficiently cope with such changes in groove shape and misalignment during welding.

SUMMARY OF THE INVENTION The present invention has been made to meet such a demand, and a groove which can easily and accurately obtain groove information by combining a roller having a groove copying function and a distance detection sensor. An object of the present invention is to provide a method for detecting the width and the amount of misalignment.

[0009]

According to a method of detecting a groove width according to the present invention, in a butt welding, a roller having a tapered shape with an outer peripheral portion having a fixed angle is provided inside a groove in front of a welding arc. The distance detecting means for measuring the distance between the corresponding left and right workpieces and the plate surface is fixed on both sides of the roller, and the groove width is calculated from the sum of the displacements of the left and right distances. Is characterized by detecting the amount of change in.

The roller according to the present invention has an outer peripheral surface formed in a tapered shape at a fixed angle θ, and these tapered surfaces follow the groove while engaging with the edge of the groove. In other words, the roller has a function of following a groove and a function of detecting a groove width and a misalignment amount. First,
Describing the detection of the groove width, when the groove width changes from the reference gap at the time of the initial setting, the contact point with the edge of the groove is displaced on the tapered surface of the roller. Therefore,
The distance between the plate surface of each of the left and right workpieces is measured by the distance detection means fixed on both sides of the roller, whereby the displacement amount Δ in the distance measurement direction of the plate surface of each of the workpieces is measured.
L is obtained, the displacement amount in the width direction of each edge point of the groove is calculated by a trigonometric function (ΔLtan
θ). Therefore, the variation amount of the groove width is obtained as the product of the sum of the displacement amounts ΔL (left) and ΔL (right) of the left and right distances and tan θ.

As described above, the detection mechanism according to the present invention is not only a simple mechanism using a combination of the tapered roller and the fixedly disposed left and right distance detection means, but also has a simple configuration in terms of arithmetic processing and the like. Therefore, it can be inexpensive,
The variation in the groove width can be accurately detected, and the responsiveness is good even when the welding speed is increased.

Further, the method for detecting misalignment according to the present invention is characterized in that, in butt welding, a roller having a tapered shape with an outer peripheral portion having a fixed angle is inserted into a groove in front of a welding arc. Disposing and fixing distance detecting means for measuring the distance between the corresponding left and right welded members and the plate surface on both sides of the roller, and detecting the amount of misalignment from the difference between the displacement amounts of the left and right distances. It is characterized by the following.

Since the misalignment between the left and right members to be welded is the amount of displacement between the left and right members to be welded in the plate thickness direction, the difference between the left and right distance displacements ΔL (left) and ΔL (right) is obtained. Can be. Therefore, it is possible to easily and accurately detect the amount of misalignment that changes with time using the same roller and the same distance detecting means.

[0014] The roller follows the groove better when it is elastically pressed with a spring or the like into the groove than when it is stationary.

The distance detecting means comprises, for example, a laser sensor. However, it is preferable that the distance detecting means is mounted on or near the shaft of the roller in order to correspond to a member to be welded having a curved portion or an inclined portion.

The present invention can be applied to both the case where the detection is performed from the front side of the member to be welded and the case where the detection is performed from the back side. Therefore, in the present invention, the “plate surface of the member to be welded” refers to the front surface or the back surface of the member to be welded.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram illustrating a method for detecting a groove width according to the present invention, and FIG. 2 is a diagram illustrating a method for detecting a misalignment amount.
FIG. 3 is a schematic diagram of a welding machine provided with these detection mechanisms. In the figure, 1 is a roller, 2a and 2b are laser sensors, 3 is a welding torch, 4a and 4b are members to be welded, and 5 is a groove.

The roller 1 has a tapered surface 1a, 1b having an outer peripheral surface having a constant angle θ. At least one roller 1 is attached to the front part of the traveling welding machine 10, and is provided so as to enter the groove 5 in front of the point where the welding arc 11 of the welding torch 3 is generated. The roller 1 has a groove following function for guiding the welding machine 10 along the groove 5. The roller 1 is preferably formed with a groove 5 by a pressing means such as a spring or a cylinder.
Press inside.

Laser sensors 2a and 2b are fixedly mounted on the welding machine 10 on both right and left sides of the roller 1, respectively. The laser sensors 2a and 2b allow the surfaces 6a and 6b of the corresponding members 4a and 4b to be respectively welded. Distance L to
Measure 1o and L2o. The mounting position of the laser sensors 2a and 2b is such that the roller 1 and the welding members 4a and 4b are engaged with each other in order to prevent an error in the measurement distance even when the member to be welded is bent or inclined. You need to be right beside. Therefore, it is appropriate to attach it to the shaft 14 of the roller 1 or its vicinity.

The welding torch 3 mounted on the welding machine 10 includes:
A welding wire 7, a tip 8, and a shielding gas nozzle 9 are provided, and a plurality of welding torches 3 are provided as necessary.
Further, the welding machine 10 includes a plurality of wheels 15, is mounted on one of the members to be welded, and travels by a self-propelled or traction method. Numeral 12 indicates a molten pool and numeral 13 indicates a weld bead.

The principle of detecting the groove width will be described with reference to FIG. First, the angle θ of the roller 1 is set to θ = 45 ° (tan θ = 1) for simplicity, and the shape of the groove 5 is I-shaped. The roller 1 follows the groove while the outer tapered surfaces 1a and 1b engage with the left and right edges of the upper end of the groove of the members 4a and 4b to be welded. If the displacement of the edge points 5a and 5b respectively contacting with each other is known, the amount of change in the groove width can be obtained.

When the members to be welded 4a and 4b are in the normal state shown by broken lines, the gap (reference groove width) of the groove 5 is Go, and the left member to be welded 4a measured by the left laser sensor 2a. L1o is the distance to the surface 6a (left plate reference distance) and L is the distance to the surface 6b of the right welded member 4b (right plate reference distance) measured by the right laser sensor 2b.
2o. Further, when the groove width changes as shown by the solid line, the groove width is G, the distance (left plate distance) from the surface 6a 'of the left welded member 4a measured by the left laser sensor 2a is L1, The distance (right plate distance) between the right welded member 4b and the surface 6b 'measured by the right laser sensor 2b is L2.
And That is, Go: reference groove width L1o: left board reference distance L2o: right board reference distance L1: left board distance L2: right board distance Then, the left welded member 4a is moved from 6a to 6a '.
And the right plate displacement ΔL when the right welded member 4b is displaced from 6b to 6b '.
2 is represented by the following equations. ΔL1 = L1o−L1 ΔL2 = L2o−L2 Therefore, the groove width G when the groove width changes is given by the following equation (1).
Required by G = Go + ΔL1 + ΔL2 (1)

That is, the displacement amount of the groove width G is the displacement amount ΔL1 of the distance of the left welded member 4a and the displacement amount ΔL1 of the right welded member 4b.
Of the distance ΔL2.

Next, the principle of detecting the amount of misalignment will be described with reference to FIG. The specifications are the same as above. Misalignment amount δ
Is the amount of displacement between the left and right surfaces of the members to be welded in the plate thickness direction, and can be obtained by equation (2). δ = ΔL2−ΔL1 (2) where ΔL1 = L1o−L1 ΔL2 = L2o−L2. At this time, the lateral displacement d between the center line 16 of the roller 1 (the center line when there is no misalignment) 16 and the center line of the groove (the center line when there is no misalignment) 17 is as follows: d = δ / 2 Becomes

An embodiment of the present invention will be described. (1) Welding conditions Leading welding current: 450 A Trailing welding current: 350 A Leading welding voltage: 36 V Trailing welding voltage: 35 V Welding speed: 15.0 cpm (2) Base material conditions Plate thickness: 19 mm Groove gap: 11 to 18 mm , I type Difference amount: 0 to 3 mm (3) Roller dimensions, mounting position and laser sensor measurement range Diameter: 120 mm Inclination angle: θ = 45 ° Distance between arc and roller center: 80 to 120 mm Laser sensor measurement range: 50 ± 10 mm 2. FIG. 4 shows a control flow used at this time. Since the inclination angle of the roller is 45 °, (L1o−L1) tan4
5 ゜ = (L1o−L1).

In step S10, the reference gap G
Laser sensor output when o = 13 mm (L1o, L2o)
Is detected. Next, at some point, the laser sensor output (L
When (1, L2) is detected (step S11), the groove gap amount is calculated by equation (1) (step S12), and the misalignment amount δ is calculated by equation (2) (step S1).
3). These calculation results are output to the welding control device, and the welding conditions such as the position of the welding torch and the welding speed are corrected (step S14).

By this welding test, the groove gap and the amount of misalignment could be accurately detected. FIG. 5 schematically shows a macro section of the first layer bead. Each figure is 19mm thick
This indicates a case where the groove width has become narrower, wider, or misaligned since the standard gap Go = 13 mm at the time of (1). In each case, the shape and quality of the butt joint were good.

[0028]

As described above, according to the present invention,
A roller whose outer peripheral portion is tapered at a certain angle,
There is an effect that the groove width and / or the amount of misalignment can be easily and accurately detected by using the distance detecting means fixed to the left and right sides.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a groove width detection method according to the present invention.

FIG. 2 is a diagram illustrating a method for detecting a misalignment amount according to the present invention.

FIG. 3 is a schematic view of a welding machine provided with a detection mechanism according to the present invention.

FIG. 4 is a control flowchart used in the embodiment.

FIG. 5 is a macro sectional view of a first layer bead in the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Roller 1a, 1b Roller taper surface 2a, 2b Laser sensor 3 Welding torch 4a, 4b Welded member 5 Groove 5a, 5b Groove edge point 11 Welding arc

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G01B 21/02 G01B 21/02 21/16 21/16 // B23K 101: 28 B23K 101: 28 (72) Inventor Yasuhiko Nishi 1-2-1, Marunouchi, Chiyoda-ku, Tokyo, Japan Inside Nihon Kokan Co., Ltd. (72) Inventor Hiroshi Murayama 1-1-2, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. F-term (reference) 2F065 AA02 AA06 AA09 AA15 AA22 AA24 AA25 BB13 CC00 CC06 DD00 FF00 FF40 GG06 HH13 KK01 MM07 PP01 PP22 QQ25 QQ27 UU01 UU02 UU03 2F069 AA02 AA06 AA16 AA42 AA44 HAGG GG BB GG GG NN00

Claims (4)

[Claims] In the butt welding, a roller having a tapered shape with an outer peripheral portion having a fixed angle is disposed so as to enter a groove in front of a welding arc, and a roller corresponding to each side of the roller is provided. A distance detecting means for measuring a distance between the left and right members to be welded to the plate surface, and a groove width change amount detected from a sum of displacement amounts of the left and right distances. Method. 2. In butt welding, a roller having an outer peripheral portion having a tapered shape having a certain angle is disposed so as to enter a groove in front of a welding arc, and a roller corresponding to each side of the roller is provided. A method for detecting the amount of misalignment, comprising fixing distance detecting means for measuring the distance between the left and right members to be welded and the plate surface, and detecting the amount of misalignment from the difference in the amount of displacement between the left and right distances. 3. The method according to claim 1, wherein the roller is elastically pressed into a groove. 4. The apparatus according to claim 1, wherein said distance detecting means is attached to or near a shaft of said roller.
The detection method according to any one of claims 1 to 3.