JP3269365B2 - Arc sensor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an arc sensor device effective for gas shielded metal arc (GMA) welding.

[0002]

2. Description of the Related Art In recent years, in automatic arc welding, a torch is made to perform a periodic motion such as a swinging operation or a rotating operation, and the center axis of the torch is constantly adjusted by a signal obtained from a change in welding current. An arc sensor that performs welding by being positioned near the center of a circle is widely used.

A specific conventional example of the arc sensor control for periodically moving the torch is disclosed in Japanese Patent Publication No. 53-11502, which is now widely used. An example in which a welding voltage is used in the conventional arc sensor control will be described with reference to FIGS.

FIG. 5 is a side view showing a welding state of arc welding to which conventional arc sensor control is applied. In FIG. 5, reference numerals 2a and 2b denote workpieces, M denotes a groove, and a central portion thereof is indicated by a chain line N. The welding tip 7 is inserted into the groove M, a welding wire 8 is sent out from the welding tip 7, and an arc is generated between the welding tips 2a and 2b during welding. As the welding torch (not shown) makes a periodic movement, the welding tip 7 fixed to the welding torch moves from 7a to 7b, then 7a, 7c and 7a.

When the center of the periodic movement of the welding tip 7 passes through the central portion N of the groove as shown in FIG. 5A, the welding voltage changes as shown in FIG. The position of the welding tip 7 is 7a becomes the welding voltage p of FIG. 6 (a), the position of 7b q, also back to the position of 7a r, s in the position of 7c, returns to 7a when p ₁ of the welding voltage become.

Next, when the center of the periodic movement of the welding tip is shifted upward from the central portion N of the groove M2 as shown in FIG. 5 (b), the welding voltage becomes as shown in FIG. 6 (b). Changes to If it is shifted downward, p on the time axis in FIG.
Is read, r is read as s, r is read as p, and s is read as q.

[0007] upper and lower half cycle of the welding voltage arc by integrating each (FIG. 6 (a), p-r and between r-p ₁ between FIG. 6 (b)), the difference between the upper and lower integral value Is calculated, the difference is multiplied by a fixed amount of gain constant, and the result is corrected for the locus,
The control is performed such that it is always located at the center N or is shifted from the center by a set amount.

[0008]

However, the above-mentioned conventional arc sensor device uses a fixed amount of gain constant which is at a predetermined standard periodic motion frequency.
Even if an optimal gain constant is set at that frequency, there is a problem that if the periodic motion frequency is changed, the gain constant must also be changed and adjusted.

An object of the present invention is to solve the above-mentioned conventional problems and to provide an arc sensor device excellent in operability in gas shielded metal arc (GMA) welding.

[0010]

In order to achieve the above object, the present invention provides a welding torch that moves periodically, a welding voltage detector for detecting a voltage between the welding torch and a workpiece, A phase detector for detecting the phase of the motion, a voltage difference calculator for calculating a difference between welding voltages in arbitrary two ranges of the periodic motion, and a gain constant multiplied by the difference voltage calculated by the voltage difference calculator. and a gain constant multiplier, cycle
Depending on the frequency of the movement, the welding torch
Set the gain constant so that the shift distance is constant
And operate the welding torch only for the calculation result of the gain constant multiplier.
It is to let .

Further, the invention of claim 2 is characterized in that the configuration of claim 1 is provided with a gain constant table corresponding to the frequency of the periodic motion.

Next, a third aspect of the present invention provides a welding torch that moves periodically, a welding current detector that detects a current flowing between the welding torch and the workpiece, and a phase detector that detects the phase of the periodic movement. A current difference calculator for calculating a difference between welding currents in any two ranges of the periodic motion; and a gain constant multiplier for multiplying the difference current calculated by the current difference calculator by a gain constant. Welding toe according to the frequency of
So that the shift amount per unit time per unit time is constant
Set the gain constant and calculate only the result of the gain multiplier.
It operates the welding torch .

Further, the invention of claim 4 is provided with a gain constant table corresponding to the frequency of the periodic motion in the configuration of claim 3.

[0014]

According to the above construction, the inventions according to the first and second aspects of the present invention are arranged such that even if the periodic motion frequency is changed for some reason, the gain is adjusted according to the frequency of the periodic motion without changing and adjusting the gain constant. The constant is automatically set, the welding torch is operated only by the calculation result of the gain constant multiplier, which is obtained by multiplying the difference voltage calculated from the welding voltage difference signal by the gain constant, and the relative position between the welding torch and the workpiece is determined. It has the effect of making it constant.

According to the third and fourth aspects of the present invention, even when the periodic motion frequency is changed for some reason, the gain constant is automatically set according to the frequency of the periodic motion without changing and adjusting the gain constant. Then, the welding torch is operated only by the calculation result of the gain constant multiplier obtained by multiplying the difference current calculated from the difference signal of the welding current by the gain constant, and has an effect of keeping the relative position between the welding torch and the work piece constant. .

Hereinafter, embodiments of the present invention will be described with reference to FIGS.
This will be described with reference to FIG. The same components as those described in the conventional example are denoted by the same reference numerals.

FIG. 1 is a block diagram of an arc sensor device according to an embodiment of the present invention. As shown in FIG. 1, in a gas shielded metal arc welding machine, a welding torch 1 that makes a periodic motion, a welding voltage detector 3 that detects a voltage between the welding torch 1 and a workpiece 2, Current detector 4 for detecting a current flowing between the workpiece 2 and the workpiece 2
A) a phase detector 5 for detecting the phase of the periodic motion, and a voltage difference calculator 6 (sensor) for calculating a difference between welding voltages in any two ranges of the periodic motion in the arc sensor 8. A current difference calculator when a current is used for the signal) and a gain constant multiplier for multiplying the difference voltage calculated by the voltage difference calculator by a gain constant. The arc sensor 8 only has a calculation result of the gain multiplier. The welding torch is operated to keep the relative position between the welding torch and the workpiece to be fixed.

FIG. 2 is a perspective view showing a weaving state of the welding tip during arc welding. In FIG.
Reference numerals 2a and 2b denote welded objects, respectively, forming a downward lap joint. A is a welding line and indicates a boundary where the workpieces 2a and 2b overlap. Reference numeral 7 denotes a welding tip, which is fixed to a welding torch (not shown). Numeral 10 denotes a welding wire, which is fed from the center of the welding tip 9, generates an arc between the workpieces 2a and 2b and melts during welding, and welds the workpieces 2a and 2b. Then, as the welding torch (not shown) makes a periodic movement called weaving, the center axis B of the welding tip 9 is moved to the workpieces 2a and 2a.
b on the draw projection line C (p-q-r- s-p 1).

The operation of the gas sensor metal arc welding (CO2 welding) arc sensor device in which the welding torch makes a periodic motion called weaving as described above will be described.

In the case of periodic movement as shown in FIG. 2, the welding voltage becomes as shown in FIG. 6 (a), but when it deviates from the center of the joint, it becomes as shown in FIG. 6 (b). The difference voltage is calculated by subtracting the average voltage from p to r from the average voltage.

As shown in FIG. 3A, when the welding voltage is used, when the frequency of the periodic motion is reduced, the welding torch is moved once per rotation (shift movement). (The number of shifts) decreases, and in a general gas shielded metal arc welding machine, the value of the difference voltage also decreases, and the amount of one movement decreases.
The shift amount of the welding torch per unit time is reduced. Therefore, a gain constant table is created from the characteristics shown in FIG. 3A so that the shift amount of the welding torch per unit time is constant, and the difference voltage is obtained from the gain constant table. The shift movement amount is calculated by multiplying the gain. FIG. 3B shows an example of the gain constant table.

The position of the welding torch in the left-right direction can be detected from the difference between the left welding voltage average value and the right welding voltage average value in the traveling direction during the periodic motion. . Generally, control is performed so that this difference voltage becomes a voltage (offset voltage) set in advance. If the absolute value of the offset voltage is small, it is closer to the center of the joint.

As shown in FIG. 4A, when the welding current is used, if the frequency of the periodic motion is changed, the shift amount of the welding torch per unit time is changed. In advance, the shift current is calculated by multiplying the difference current by the gain obtained from the gain constant table. FIG. 4B shows an example of the gain constant table.

[0024]

As described above, according to the first aspect of the present invention,
A welding torch that moves periodically, a welding voltage detector that detects a voltage between the welding torch and the workpiece,
A voltage difference calculator for calculating a difference in welding voltage in a range of locations,
By providing a gain constant multiplier for multiplying the difference voltage calculated by the voltage difference calculator by a gain constant, even if the periodic motion frequency is changed, it is possible to respond to the frequency of the periodic motion without changing and adjusting the gain constant. Therefore, the gain constant can be automatically set, so that there is an excellent effect that the operability is improved in the case of gas shielded metal arc welding in which a sensor signal is easily output at the welding voltage.

According to the second aspect of the present invention, since the configuration of the first aspect is provided with a gain constant table for the frequency of the periodic motion, the gain constant is changed even when the periodic motion frequency is changed. Since the gain constant can be automatically set according to the frequency of the periodic motion without adjustment, an excellent effect that operability is more easily improved in the case of gas shielded metal arc welding is achieved.

Next, according to the third aspect of the present invention, a welding torch that moves periodically, a welding voltage detector that detects a current flowing between the welding torch and the work to be welded, and a welding voltage detector that detects any two positions of the periodic movement. By providing a current difference calculator for calculating a difference between welding currents and a gain constant multiplier for multiplying the difference current calculated by the current difference calculator by a gain constant, the gain constant can be maintained even when the periodic motion frequency is changed. Since the gain constant can be set automatically according to the frequency of the periodic motion without changing and adjusting the frequency, the excellent effect that operability is improved in the case of gas shielded metal arc welding where a sensor signal is easily generated by the welding current is obtained. To play.

According to the fourth aspect of the present invention, the configuration of the third aspect is provided with a gain constant table for the frequency of the periodic motion, so that the gain constant is maintained even when the periodic motion frequency is changed. Since the gain constant can be automatically set according to the frequency of the periodic motion without changing and adjusting, an excellent effect that operability is more easily improved in gas shielded metal arc welding is achieved.

[Brief description of the drawings]

FIG. 1 is a block diagram of an arc sensor device according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a weaving state of a welding tip.

3A is a characteristic diagram showing a difference voltage and the number of shifts with respect to a periodic motion frequency. FIG. 3B is a characteristic diagram showing a gain constant table.

4A is a characteristic diagram showing a difference current and the number of shifts with respect to a periodic motion frequency. FIG. 4B is a characteristic diagram showing a gain constant table.

FIG. 5 (a) is a side view showing a welding state when the central axis of the conventional weaving operation is located at the center of the groove; and (b) the central axis of the conventional weaving operation is from the central part of the groove. Side view showing the welding state when it is off

FIG. 6 (a) is a waveform diagram of a welding voltage when the central axis of the conventional weaving operation is located at the center of the groove; FIG. 6 (b) is a central axis of the conventional weaving operation where the central axis is the groove; Waveform diagram of welding voltage when deviated from

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 welding torch 2 workpiece 3 welding voltage detector 4 welding current detector 5 phase detector 6 voltage difference calculator (current difference calculator) 7 gain constant calculator 8 arc sensor

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-61-74778 (JP, A) JP-A-7-24574 (JP, A) JP-A-3-161172 (JP, A) JP-A-3-3 161171 (JP, A) JP-A-59-191575 (JP, A) JP-A-60-30580 (JP, A) JP-B-2-3670 (JP, B2) (58) Fields investigated (Int. ⁷ , DB name) B23K 9/127 B23K 9/10 B23K 9/12

Claims (4)

(57) [Claims] A welding torch that moves periodically; a welding voltage detector that detects a voltage between the welding torch and a workpiece;
A phase detector for detecting the phase of the periodic motion, a voltage difference calculator for calculating a difference between two arbitrary welding voltage ranges of the periodic motion, and a gain constant for the difference voltage calculated by the voltage difference calculator. And a gain constant multiplier that multiplies the shift shift of the welding torch per unit time according to the frequency of the periodic motion.
An arc sensor device that sets the gain constant so that a moving amount is constant, and operates the welding torch only by a calculation result of the gain constant multiplier. 2. The arc sensor device according to claim 1, wherein the gain constant is set using a gain constant table corresponding to the frequency of the periodic motion. 3. A welding torch that moves periodically, a welding current detector that detects a current flowing between the welding torch and an object to be welded, a phase detector that detects the phase of the periodic movement, and any two of the periodic movement. comprising a current difference calculator for calculating a difference between the welding current in the range of locations, and a gain constant multiplier multiplying the gain constant the difference current calculated by the current difference calculator, welding torch according to the frequency of the periodic motion Per unit time
Shift movement amount setting the gain constant to be constant, to operate the welding torch by the calculated results of the gain multiplier
That arc sensor device. 4. The arc sensor device according to claim 3, wherein a gain constant is set using a gain constant table corresponding to the frequency of the periodic motion.