JPS5849184Y2 - Weld line confirmation device - Google Patents

Description

[Detailed description of the invention] The present invention relates to a device for detecting a welding line with a sensor and checking whether a welding torch is at a predetermined position with respect to the welding line of a workpiece. .

Welding can be carried out by fixing the workpiece and moving the welding torch along a predetermined trajectory, or by fixing the welding torch and rotating or moving the workpiece in a straight line. In automatic welding equipment that performs welding by moving the torch and workpiece relative to each other, the welding torch is in a mechanically determined position, so the trajectory drawn by the welding torch relative to the workpiece is based on the welding equipment. Binding (
It will draw a fixed trajectory.

On the other hand, the weld line of the object to be welded is not necessarily in the correct position, and some deviation occurs.

If this positional deviation is significant, the welding torch and welding line will be too far apart, making it impossible to obtain a satisfactory welding result.

As a countermeasure for this, there is a method in which a sensor is moved at the same time as the welding torch to detect the positional deviation of the welding line, and the position of the welding torch is made to follow the welding line, and a method in which the welding torch is oscillated in a direction perpendicular to the welding line. , welding methods are widely used.

However, the copying device requires a complicated and expensive position adjustment mechanism and control device for the welding torch, and the oscillation method has a limited tolerance for positional deviation, making it difficult to employ in mass-produced welding devices.

In general, the position of the weld line of a welded object intended for mass production varies from production lot to production lot, but the variation within the same lot is small and often has little effect on the welding result.

Therefore, even without installing a particularly expensive copying device,
For simple shapes (straight lines or circles), a single sensor is used, and for complex curves, multiple sensors are used to ensure that the position of the weld line is within an acceptable range relative to the defined trajectory of the welding torch before welding begins. By confirming whether or not there is a weld, a sufficiently satisfactory welding result can be obtained without using complicated and expensive equipment as in the conventional method described above.

In addition, since the position of the welding line is rarely detected by the sensor, it is sufficient for practical use to stop the welding machine before welding by using an alarm or a welding machine stop signal.

This invention uses one or more sensors to detect the position of the welding line on the workpiece, and if any one of the sensors detects a positional defect in the welding line, it outputs an alarm or a welding machine stop signal. We propose a weld line confirmation device that
In particular, by setting up a model weld line that shows the standard state of the weld line at the sensor retraction position and using it as a reference when detecting the weld line, it is possible to detect differences in wall thickness of the workpiece, steps in the weld, size of gaps, and differences in sensor characteristics. This prevents errors caused by such factors.

FIG. 1 is a diagram illustrating the use of the device of the present invention for butt circumferential welding of pipes.

In the figure, 1a to 1d are welding line position detection sensors, which are provided at four locations: upper, lower, left, and right.

The sensors 1a to 1d are driven by a drive means (not shown) and rotated through 90 degrees.

2a to 2d are model welding lines, and the objects to be welded 3, 3
As a reference for the welding line 4 ', the welding line 4 is made of the same material as the workpiece and has the same shape.

Each model weld line is accurately aligned at the retracted position of each sensor.

5a to 5d are non-inverting amplification circuits that receive the outputs of the sensors 1a to 1b; 6 are amplification circuits 5a to 5;
This is a discrimination circuit that receives each output signal of d, and when using a sensor 1a to 1d that outputs a low level signal (L signal) when the weld line position is good (or a high level signal (H signal) when it is defective). Use OK open circuit.

Reference numeral 7 denotes an output relay, which is operated by the H signal from the discrimination circuit 6.

Prior to welding, each of the sensors 1a to 1d detects the model welding line in the retracted position shown by the dotted line in FIG. .

Next, each sensor is moved to a position facing the welding line 4 of the objects to be welded 3, 3' by a driving means (not shown).

At this time, the outputs of the sensors 1a to 1d are amplified by amplification circuits 5a to 5d, respectively, and then input to the discrimination circuit 6.

In the discrimination circuit 6, if even one of the outputs of the width increasing circuits 5a to 5d is an H signal (welding line defect signal), an H signal is outputted and the output relay is energized.

The contact point of the output relay will alert you to a defective welding line, display it, or stop the welding machine.

When using a sensor in which the output characteristics of the sensors 1a to 1d are reversed, that is, an H signal is generated when the weld line position is good, and an L signal is generated when the weld line position is poor, an AND circuit is used for the discrimination circuit 6, or an amplification circuit is used. An inverting amplifier may be used for this purpose.

FIG. 2 shows an example of a sensor for magnetically detecting the position of a weld line used in the present invention.

In FIG. 2, 101 is an exciting coil, and the iron core 1
02, and an alternating current is passed through it by a power source S.

W is an object to be welded, and the butt portion Wo is to be welded.

103, 103' are differentially interconnected detection coils, which generate voltage e103. as shown in FIG. e103 dormitory induced.

As for the output of the sensor, since the two detection coils are connected differentially, when the center of the sensor coincides with the abutment part WO, the differential voltage (e103-103") becomes almost zero, and from WQ Once it gets out of the way a little, it increases rapidly, clearly indicating that it has moved away from the weld line.

FIG. 3 shows the change in the output value at this time.

In the figure, the horizontal axis indicates the relative position of the sensor and the welding line Wo, and the vertical axis indicates the output voltage.

As can be seen from the figure, the portion where the output voltage is approximately zero is determined to be the weld line.

The weld line detection sensors used in this invention include those that use a non-contact magnetic property as shown in Figure 2, those that use a light source and a photoelectric element, those that use ultrasonic waves, etc. Other types of non-contact sensors may also be used, and in cases where the weld line has a groove or fillet welding,
A sensor may be used in which a contactor is brought into direct contact with the welding line.

Furthermore, if the moving devices to which the sensors are attached are operated in sequence so that signals indicating poor position of the weld line are not output at the same time, the number of amplifiers can be reduced to one.

In other words, if the sensor outputs an L signal when the weld line position is good, and an H signal when the weld line is defective, then at the retracted position the sensor outputs the same L signal as when the weld line position is good. If even one of the outputs of the sensor generates an H signal to the amplifier, it can be determined that the weld line is in a positional defect.

In addition, the amplification circuit not only amplifies the output of the sensor, but also stores the output when detecting the model weld line, and compares the detected value with the previously stored model value when actually detecting the weld line. Detection accuracy can be further improved by configuring to output a weld line defect signal when the difference between both signals exceeds a certain tolerance value.

FIG. 4 is a configuration diagram showing an example of the amplification circuit at this time,
11 is a memory circuit, 12 is a comparator circuit, and 13 is a reference signal source for setting a tolerance range, which includes a power supply 131 and a potentiometer 132.

In the figure, a detection signal from a sensor inputted from terminal a is stored in a storage circuit 11 by a model detection storage command button PB.

Next, when the sensor is faced to the actual workpiece, terminal a
The input signal is input to the comparison circuit 12 and compared with the previously stored output signal of the storage circuit 11.

When the difference between the detection signal and the stored signal exceeds the reference signal set by the power supply 131 and potentiometer 132, an H signal is output to the output terminal.

As described above, according to the device of the present invention, a number of sensors corresponding to the positions at which welding lines are to be detected are provided, and the position of the welding line of the workpiece relative to the position of the welding torch is determined before welding starts. Since this can be confirmed, it is possible to obtain a device that is highly reliable over a long period of time without requiring special considerations such as gain adjustment of the amplifier and disturbances caused by the welding current, unlike when using a copying device.

Furthermore, in the present invention, a model welding line indicating the standard state of the welding line of the workpiece is placed at the retracted position of the sensor, and the quality of the welding line position is determined based on this model welding line. Even if there are steps in the welded workpiece, gaps between the opposing parts of each sensor are different, or variations in the characteristics of each sensor, the accuracy of weld line confirmation can be significantly improved without being affected in any way.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing an example of the device of the present invention, Fig. 2 is a diagram showing an example of a sensor, Fig. 3 is a diagram showing the output of each part of the sensor in Fig. 2, and Fig. 4 is an amplification circuit. FIG. 1a to 1d...Welding line detection sensor, 2a to 2d...Model welding line, 4...Welding line, 5a to 5d...Width increasing circuit, 6...
...Judgment circuit.

Claims (1)

[Claims for Utility Model Registration] (1) One or more sensors for detecting the quality of the welding line position of the welding proboscis corresponding to the welding torch, and a retraction mechanism for retracting each of the sensors from the welding line detection position; , a model welding line provided corresponding to each sensor at the retracted position of each sensor, an amplification circuit that receives the output of each sensor as input, and an amplification circuit that receives the output of the amplification circuit as input and outputs the output of each sensor. A welding line confirmation device comprising a discrimination circuit that outputs an alarm or a welding machine stop signal when at least one of the welding line position defects is detected. 2. The welding line confirmation device according to claim 1, wherein the same number of the width increasing circuits as the sensors are provided, and the zero point adjustment is performed at the retracted position of the sensor. 3. The amplification circuit is a single amplification device, and the discrimination circuit outputs an alarm or a welding machine stop signal when the input of the amplification device is a defective signal of 11 or more. A welding line confirmation device according to claim 1 of the utility model registration claim. 4. The above-mentioned sensor always detects the model welding line in the retracted position, and the sensor is sequentially moved one by one from the retracted position to the detection position when confirming the welding line. Claim No. Welding line confirmation device described in Section 3. 5. The amplification circuit compares the output of the memory circuit with the output of the sensor when detecting the weld line, and calculates the difference between the two signals. The welding line confirmation device according to claim 1, comprising a comparator that generates an output when a signal exceeds a certain value.