JPS591505B2 - Method and device for detecting center between weld groove surfaces - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of tracing and detecting a welding groove centerline using a vibrating piece, and a structure of the apparatus.

Conventional copying devices For example, devices for copying and detecting the center line of a welding groove include V-shaped groove surfaces 1a and Ib as shown in FIG.
means for pressing the rounded contact rod 2 onto the bottom of the second
As shown in the figure, in the case of an I-type groove, the groove surface 3a is the side wall of the groove part.
, means for pressing the contact rod 2 against one side of the base material 4, for example, the side 3a, or as shown in FIG. There are various means, such as contact type groove line detection members 2, 5, etc., and the amount of displacement thereof is detected by a limit switch, a differential transformer, etc., and some of them are in practical use. However, in the means shown in FIGS. 1 and 2, the contact rod 2
The mechanical play caused by rubbing against the groove surfaces 1a, lb, and 3a, the structurally large contact rod 2, and the interference with welding arc monitoring make work difficult. The accuracy was also worse than ±0.5 mm. In addition, for narrow gap welding of I-type groove,
When the method shown in the figure is adopted, the position of the groove surface is traced from one side, and the groove centerline itself, which is necessary when narrow gap arc welding is performed by the one-layer, one-bus method, cannot be detected. On the other hand, although the method shown in FIG. 3 can detect the groove center line 6, the structure of the detection part becomes considerably large, and it is limited to tracing the surface of the base material. As shown in the figure, if there is a difference in level on the surface of the base material 4, a large error may occur between the groove center line 6 and the roller center line T, which is problematic from a practical standpoint. Ta. In addition, as shown in Fig. 5, there is a method of using a magnetic non-contact type detector 8 that applies the principle of a proximity relay as a conventional left-right groove tracing device for welding, but due to structural problems, the detection It has many limitations and disadvantages, such as the large size of the device, which cannot be inserted into an I-type narrow groove with a groove width of 8 mm, and the only way to do so is to follow the groove corner 4a on one side of the surface of the base material. It was hot.

This invention eliminates the above-mentioned drawbacks of the prior art, and uses a vibrating element to detect the relative position to an object, and in particular, for welding, it can be positioned on the inner surface of a narrow I-shaped groove such as a groove width of 8 mm. The purpose of the present invention is to propose a groove center line tracing detection method and device that can detect the groove center position.

In short, this invention vibrates the vibrating piece in a state that resonates or is close to resonance, and brings its end into contact with the left and right walls of the groove, and uses the contact signal to determine the relative position between the center of amplitude of the vibrating piece and the center line of the groove. The present invention is characterized by proposing a method for detecting and performing high-quality welding and the structure of the device.

Embodiments of the present invention will be described in detail below with reference to the drawings.

Fig. 6 is a front view showing the basic configuration of the detector according to the present invention, and Fig. 7 is a side view of the detector shown in Fig. 6, also showing the main electric circuits. be. In these drawings, reference numeral 9 denotes a DC motor, which is connected to an AC power source 10 of, for example, 60 Hz, so that the rotating shaft 11 of the motor 7 is a reciprocating rotating part, that is, vibrates at 60 Hz, depending on the frequency of the AC power source. . Reference numeral 12 is a vibrating piece that functions as a contact point for groove tracing, and 13 is a center setting vibrating piece for fixing the center of vibration of the vibrating piece 12, which is lightly supported by a fulcrum 14 to fix the vibration nodes. has been done.
One ends of the vibrating piece 12 and the center setting vibrating piece 13 are connected to and fixed to the rotating shaft 11 of the motor by a tightening jig 15. Reference numeral 16 denotes a fixing block that fixes a DC motor (hereinafter referred to as a motor) 9, a fulcrum 14, etc., and is attached so as to move together with a welding torch or the like.

Reference numeral 17 denotes a contact state detection circuit that detects the electrical contact state between the left side groove inner surface 18a, right side groove inner surface 18b of the base material 18, and the vibrating element 12. A signal from the contact state detection circuit 17 is sent to a control box 41, and a welding machine centering and driving device 43 mounted on a pedestal 42 to which a fixed block 16 is attached.
The torch 44 of the welding machine 45 is aligned with the center line of the groove. In other words, the arc is correctly formed at the arc point, which is the center line of the groove. The groove centerline holding device consists of a control box 41, a pedestal 42, and a welding machine centering device 43. Incidentally, the fulcrum 14 and the motor 9 are fixed to a fixing block 16 with screws (not shown).

Since the present invention has such a configuration, when an AC voltage is applied to the DC motor 9 from the AC power supply 10 to this detector, the rotating shaft 11 of the motor rotates and reciprocates without being used. Torsional vibration is applied to a vibration system consisting of a vibrating piece 12 made up of a plate, a center setting vibrating piece 13, and a tightening jig 15. The vibration is caused to vibrate symmetrically around the center line 19 of vibration in a resonance or near-resonance state with the rotation axis 11 of the vibration center as a fulcrum.

The mode of vibration of the vibrating piece 12 and the swing width of the tip of the vibrating piece can be determined by changing the length, thickness, Young's modulus, and moment of inertia around the rotation axis 11 of the vibrating piece 12, and also by changing the center setting vibrating piece 13. It changes significantly by changing similar factors. Although FIG. 8 shows the first-order vibration mode, FIG. 9 similarly shows the second-order vibration mode of the vibrating element 12 obtained by changing the various factors mentioned above. Now, the above-mentioned factors for the vibration system are adjusted to determine the frequency f of the AC power supply 10 and the resonance frequency F of the vibration system of the detector.

When the vibration system is maintained in a resonant state by matching the values, the amplitude of vibration at the tip of the vibrating element 12 becomes extremely large, as shown by the broken line in FIG. In this state, when the base material groove surface 18a is applied to one side as shown in FIG. The vibrating width c on the opposite side to the base material groove surface 18a is almost equal to the distance b between the base material groove surface 18a and the original vibration center line 19. A phenomenon occurs.
In I-type narrow gap welding, the base metal groove surfaces 18a on both sides of the groove
, 18b are at the same potential because they are welded, but the vibrating element 1
2 is in a state of uneven contact with the groove surface of the dora,
Alternatively, there is a problem in detecting whether there is a hit on both sides or whether there is a hit on both sides, but this was solved as follows.

To detect whether or not the vibrating piece 12 has contacted the base material 18, as shown in FIG. This was done using Therefore, the relative position detection device for detecting the relative position between the detector and the bevel part is composed of a vibration system device including a center setting vibrating piece 13, a tightening jig 15, and a vibrating piece 12, and a contact state detection circuit 17. It will become. Now considering the case where the vibrating piece 12 is vibrating in the first-order mode, when the voltage of the AC power supply 10 applied to the motor 9 is a positive half wave, the tip of the vibrating piece 12 is on the left side groove surface 18a of the base material. Conversely, when the vibrating element 12 is connected so as to swing toward the right groove surface 18b of the base material, the tip of the vibrating element 12 operates so as to swing toward the right side groove surface 18b of the base material during a negative half wave.

Therefore, the input terminal A of the signal discrimination circuit 26 shown in FIG.
The voltage signal of the father flow power supply 10 is added to input terminal B27, and the contact state detection voltage signal from the contact state detection circuit 17 is added to the input terminal B28 as an input signal, respectively, and the contact state is detected when the voltage signal of the AC power supply 10 is a positive half wave. the state of the voltage signal of the circuit 17;
The state of the voltage signal of the contact state detection circuit 17 when the voltage signal of the AC power supply 10 is a negative half wave is identified, and the state of the voltage signal of the contact state detection circuit 17 is identified, and
A contact state detection signal on the side 8a is obtained as an output signal at the output terminal L29, and a contact state detection signal on the right groove surface 18b of the base material is obtained as an output signal at the output terminal R3O. In actual welding line groove tracing, the fixed block 16 of the detector shown in FIGS. 6 and 7, the welding rock 45, and the welding torch 44 are mechanically connected so that they move as one. It is mounted on a moving base (not shown) that moves reversibly in the left and right directions at right angles to the welding direction and in the left and right directions by an electric motor included in the drive device 43, and moves and stops the moving base in the left and right directions in a state where the left and right sides are in contact. Detection signal output 29, 30 (12th
(see figure), that is, when the vibrating element 12 is in partial contact with the left groove surface 18a, the moving base is moved to the right side, and the vibrating element 12 is in partial contact with the right groove surface 18b. When the moving base is on the left side, and the vibrating piece 1 is
This was carried out using a circuit configured to stop the movement of the moving base if 2 was a double hit.

FIG. 13 shows the relationship between groove width and detection accuracy, which is the result obtained by implementing the present invention. The solid line indicates the first mode of the vibrating element, and the dotted line indicates the second mode. According to the embodiment of the present invention described above, the motor 9 is a small motor with a diameter of 25 m, a length of about 30 m, and the center setting vibrating piece 13 is a small motor with a length of 35 m, a width of 9 mm, and a thickness of 0.3 m.
The detector structure was extremely simple and compact because it used a spring plate of 1.5 mm.

Since the vibrating piece 12 is made of a 17%Cr-7%Ni-1%At spring material, it has extremely good heat resistance, and the vibrating piece 12 can be vibrated with an amplitude greater than the groove width to prevent damage to the surface of the base material. Even if the vibrating element 12 is inserted from the outside into the groove of the base material fairly rapidly, the vibrating element 12 can be inserted into the groove without getting caught on the surface of the base material. A commercial frequency is used as the contact state detection circuit 17.
Despite the fact that the other electric circuits had simple circuit configurations and were manufactured to be extremely simple, inexpensive, durable, and long-lasting, extremely good detection accuracy was obtained as shown in FIG. 13. Furthermore, even in a narrow groove with a groove width of about 8 mm and a plate thickness of nearly 100 mm, the groove center line 20 near the groove bottom can be sufficiently detected, as shown in Fig. 13. As described above, even if the groove width changes, the groove center line 20 can be directly and easily detected and followed. In all of the above examples, a large amplitude was obtained with a small input energy by vibrating the vibration system at or near resonance, but by increasing the input energy, it was possible to obtain a large amplitude. Even by using the vibration in the non-resonant state obtained by this method, it was possible to perform a similar tracing operation along the groove centerline.

Further, as a method of applying vibration energy, the method using the motor 9 as shown in FIG. 6 has been mainly explained, but the method is not limited to the motor 9.

FIG. 14 shows an example of another vibration energy application method, in which a coil 34 is wound around the iron core 33 of a magnetic circuit consisting of a permanent magnet 31, a yoke 32, and an iron core 33, and an alternating current is applied to the coil 34. When an AC voltage is applied from the power source 35, the vibrating piece 37 held by the support plate spring 36 and the iron core 33 vibrates.By applying the principle of such a torque motor, the vibration causes the rotation axis of the motor to vibrate. It can also eliminate the problem of wear. By carrying out the first invention and the second invention, the center between the surfaces of the welding groove can be detected with high accuracy because the center between the surfaces of the vibrating element is detected in the resonant state.

Furthermore, since the vibration frequency is large, there is a large amount of information regarding the position of the vibrating element holder within a unit time, and extremely accurate control can be performed. Even if the surfaces to be detected are discontinuous, that is, the dimensions between the surfaces change discontinuously, the center between the surfaces can be detected circularly and with high precision. When carrying out the third invention, since the groove centerline is detected while vibrating the vibrating piece within the base material groove, (1) a long vibrating piece can be used, and a narrow vibrating piece can be used; (2) Since the arc can be easily seen through the movement of the vibrating piece, monitoring of the arc, which is a particular problem in narrow groove welding, is not obstructed. (3) It is a detector that directly follows the groove center line (arc point) required for narrow groove welding using the I-layer 1-pass method. (4) The detection accuracy of deviation from the groove center line is ±0. ．．
Practical sufficient accuracy such as 15mm can be easily obtained (
5) Since the contact with the side wall of the groove is vibratory, there are no problems with the conventional technology such as sticking due to rubbing with the base material surface, and a simple detector is used. Despite its structure, it has extremely excellent functionality as a groove copying device, especially for narrow gap welding, and has various effects such as greatly contributing to the automation of welding work. .

[Brief explanation of the drawing]

Figures 1 and 2 are diagrams for explaining the conventional means using a contact rod, Figures 3 and 4 are diagrams for explaining the conventional means using an abacus-shaped contact body, and Figure 5 is for magnetic 6 is a front view of the device according to the present invention, FIG. 7 is a side view thereof, and FIG. 8 is a front view of the vibrating element showing the vibration state of the primary mode. Fig. 9 is a front view of the vibrating element showing the vibration state of the secondary mode, Fig. 0 is an explanatory diagram of the operating state of the vibrating element of the detector according to the present invention, and Fig. 11 is an explanation of the operating principle of the vibrating element. 12 is a signal identification circuit diagram from the vibrating element, FIG. 13 is a line diagram showing measurement data of tracing accuracy of the detector according to the present invention, and FIG. 14 is a diagram showing an example of a device for vibrating the vibrating element. It is. 1a, 1b, 3a, 3b... Groove surface, 2...
...Contact body, 4a, 4b-... Open end, 5.
...Copying roller, 6...Bevel center line, 8
......Non-contact type detector, 9...--DC motor, 10...AC power supply, 11...Motor rotation axis, 12...・Vibration piece, 13...
- Vibration piece for center setting, 14...Fully point.

Claims (1)

[Claims] 1. In a method of detecting the center between opposing weld groove surfaces using a contact piece, the contact piece is vibrated at resonance or in a state close to resonance, and the center between the weld groove surfaces of the contact piece is detected. 1. A method for detecting a center between weld groove surfaces, the method comprising detecting the center between weld groove surfaces using a contact between the weld groove surface and a portion that forms a maximum amplitude in a direction as a signal. 2. A vibration imparting device that vibrates a vibrating piece in a state of resonance or near resonance, and a vibration between the welding groove surfaces using the contact of the vibrating piece that contacts either or both of the opposing welding groove surfaces as a signal. A relative position detection device detects the relative position between the center and the amplitude center of the vibrating piece, and a signal from this relative position detection device detects the deviation in the relative position between the amplitude center of the vibrating piece and the center between the facing weld groove surfaces. A welding groove face-to-face center detection device characterized by comprising: a face-to-face center holding device for correcting and guiding the welding groove; 3. Claim 2, characterized in that a DC motor is used as the vibration imparting device, the vibrating piece is mechanically connected to the DC motor, and an AC power source is connected to the DC motor to vibrate the vibrating piece. The device for detecting the center of the welding groove between surfaces as described in 2.