JPS61238469A - Short circuit and arc discriminating method in consumable electrode type arc welding - Google Patents

Abstract

PURPOSE:To enable the accurate discrimination of an arc and short circuit in all current zone by comparing the decision level and the detected value of the welding voltage with the value adding the constant to the product of the proportional factor and welding current as the decision level. CONSTITUTION:The voltage detector 7 detects the voltage V between a feeding tip 4 and welding base metal 6. The current detector 8 detects the welding current I through feeding lines 2, 3. A proportional factor R is set to a setter 9 and constant K to a setter 10. The welding current I detected by the current detector 8, constant K and proportional factor R are inputted into a computing element 11 accordingly and the primary property discriminating level of Vn=k+RX1 is operated. The detected welding voltage V of the voltage detec tor 7 and discriminating level Vn are then compared by a comparator 12 and in case of V>Vn an arc signal Ar is transmitted to a welding power source device 1 and in case of V<Vn a short circuit signal S. The welding power source device 1 controls the output to the arc set output value on receipt of the arc signal Ar and adjusts the output to the short circuit set output value on receipt of the short circuit signal S.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for distinguishing between a short circuit and an arc in consumable electrode arc welding involving short circuits.

[Conventional technology]

In this type of arc welding, spatter is reduced and welding quality is It is known that workability can be improved, but this requires accurate discrimination between short circuits and arcs.

[Problem that the invention seeks to solve]

However, conventionally, the discrimination level is fixed to distinguish between short circuits and arcs. , it often happens that a short circuit is incorrectly determined even though it is an arc. This will be explained in detail below.

In consumable electrode type arc welding, the voltage at the time of short circuit is vS
, and when the voltage during a short arc immediately before a short circuit or immediately after arc regeneration is Va, these are expressed by the following formula.

Vs=RXI・・・・・・・・・・・・・・・(1)
Va=V(I)+RXI=・=(2) Here, R (hereinafter referred to as the proportional element) is the resistance of the welding wire protrusion (protrusion from the welding tip), wire material Y1 wire diameter φ and the protrusion length l of the wire from the power supply tip. For example, when the wire material Y is determined, it can be expressed as R=f (φ, 1). It has been confirmed through experiments by the inventors that this proportional element R is expressed by a linear equation, and when the material Y is YCW-2, R=0.91+6 (mA)・Wire diameter 0. 9 m
mR=0.7A→-3(mJ'l)・Wire diameter IJm
mR=0.31 +0.8 (mA) ・Wire diameter, 6 mm (3) An experimental formula was obtained.

Further, ■ is the welding current, and V (I) is the arc voltage drop, which changes depending on the current (■).

Figure 3 shows the wire diameter, 2φ welding wire (material YCW-
2) shows the current-voltage characteristics during welding. In the figure, straight lines A and B indicate the characteristics during arcing,
Straight lines X and B' represent the characteristics at the time of short circuit, and straight line N represents the conventional discrimination level.

In this way, the voltage-current characteristic exhibits almost a linear characteristic, and its slope (proportional element) is determined by the wire material Y and the wire diameter φ.
Conventionally, a constant value shown by the straight line N is used as the discrimination level, even though it changes depending on the wire protrusion length l.
The lower the current range, the more the discrimination level N and arcing voltage VaO.
When the difference becomes small, and conversely in the high current range, the difference between the discrimination level N and the short circuit special voltage Vs becomes small, so as mentioned above, it is possible to judge that there is a short circuit even though it is in an arc,
There is a problem in that an arc may be determined even though a short circuit is occurring, leading to erroneous control of the welding power source, making it impossible to achieve the above-mentioned intended purpose.

[Purpose of the invention]

The present invention has been made to solve the above problems, and it is possible to accurately distinguish between a short circuit and an arc, and the welding power source can reliably and immediately respond to a change in state and accurately send out an output suitable for the state. The purpose of this study is to obtain a method for determining short circuits and arcs in consumable electrode arc welding.

[Means to solve the problem]

In order to achieve the above object, the present invention has a configuration in which a value obtained by adding a constant to the product of a proportional element and a welding current is used as a discrimination level, and calculations and comparisons are made using the discrimination level and a detected welding voltage value. be.

〔Example〕

FIG. 1 is a block diagram showing an output control device for a welding power source embodying the present invention. In the figure, 1 is a welding power supply device, 2 and 3 are power supply lines, 4 is a power supply tip, 5 is a welding wire, and 6 is a welding base material. Reference numeral 7 denotes a voltage detector, which detects the voltage ■ appearing between the power supply tip 4 and the welding base material 4. A current detector 8 detects the welding current I through the power supply line 2.3. Note that Arc indicates an arc.

Reference numeral 9 represents a proportional element setting device, and the equation (1) and (2) are
R (proportional element) explained in relation to the formula is set. 10
is a constant setter, and a constant k is set therein. Reference numeral 11 denotes an arithmetic unit, into which the proportional element R and constant k are input, and the welding current detected by the current detector 8 is derived, and +RX is input to the primary characteristic discrimination level Vn Vn= of the following equation (4). I ・ ・ ・ ・ ・ ・ ・
・ ・ ・ ・ ・ Calculate (4). 12 is a comparator, which derives the welding voltage V detected by the voltage detector 7 and the above-mentioned discrimination level Vn; (b) In the case of V<Vn: A short circuit signal S is sent to the welding power supply device 1.

When the welding power supply device 1 receives the arc signal Ar, it controls the output to the arc set output value, and when it receives the short circuit signal S, it adjusts the output to the short circuit set output value.

The proportional element setter 9 is configured as shown in FIG. 2, for example. In the same figure, 91 is a welding wire diameter setting device;
2 is a welding wire protrusion length setting device, and 93 is a welding wire material setting device, which respectively sets the welding wire diameter φ and the welding wire protrusion length! , material Y are set, and the set values are input to the calculator 94.

The calculator 94 calculates the proportional element R= based on the above φ, l and Y.
Compute and output f (φ, β, Y).

Next, the discrimination level Vn having the first-order characteristic expressed by the above equation (4) will be explained.

The constant of the first term of this discriminant is Q<k<V (1))(
A value within the range of the first term in equation (2) above is selected, and in reality, it is approximately the middle value of the above range. The discriminant is the second
Since the term is the same as the second term of equation (1) above, when the constant K is set as above (setting it, it shows a first-order characteristic that is parallel to the short-circuit voltage Vs and the arcing voltage Va with a certain interval apart). It turns out.

For example, when using a welding wire with a welding material of YCW-2 and a welding wire diameter of 2 (assuming that the range of change in wire protrusion length is small), setting R = 0.023 and K = 8 volts, The discrimination level Vn is a straight line shown by the dotted line M1 in Fig. 3, which is almost parallel to the voltage/current characteristic B when the wire protrusion length is short during an arc and the voltage/current characteristic A' when the wire protrusion length is long during a short circuit. However, it can be seen that in the current range from 0 to 600 amperes, the discrimination level has an interval between characteristic B and ni that sufficiently exceeds the erroneous discrimination range.

Therefore, when the wire diameter φ is constant, the wire protrusion length l
In the practical variation range (shaded area), there is no risk of the comparator 12 making a misjudgment, and it accurately discriminates between an arc and a short circuit in the entire current range.

Even if the wire material Y is the same, the voltage and current characteristics during welding change as shown in Fig. 4 when the wire diameter changes. Set it again and adjust the value of proportional sR.

This will be explained with reference to FIG. In the same figure, C, D
, E, F are voltages during arcing Va%C', D', D', F
' indicates the voltage Vs at the time of short circuit, wire diameter φ is 0.9 mm
In this case, when 0.027 is given as the proportional element R, the discrimination level Vn becomes a straight line shown by the dotted line M4 in the figure, which is characteristically almost parallel to C'. Also, the wire diameter φ
However, in the case of 6, if 0.013 is given as the proportional element, the discrimination level Vn becomes a straight line shown by the dotted line M3 in the figure, which is almost parallel to the characteristics F and D'.

The straight line M2 shows the discrimination level when the proportional element R is 0.02.In the high current range, it approaches characteristic F and characteristic C', but it does not approach to the extent that it will cause misjudgment, so this discrimination level can be commonly used for welding wires with wire diameters in the range of 0.9 to 6.

In this way, one discrimination level may be configured such that a plurality of wires 91 generate one setting value for the unit.

In addition, on each of the above sides, assuming that the range of change in the wire protrusion length is small, the material Y and the wire protrusion length β are constant,
The case where the proportional element R is adjusted by changing the wire diameter φ has been described, but in the case of usage in which the wire protrusion length changes significantly, the wire protrusion length is detected and the detected value is used to adjust the proportional element R. 94 may be used to perform the calculation shown in equation (3) above. Of course, even if the range of change in the wire protrusion length is small, a more accurate discrimination level can be obtained by determining the value of the proportional element R by considering the wire protrusion length l.

In the above embodiment, the arithmetic unit 11 and the comparator 12 execute the calculation VJk+R・■, but V−
R-1 to koji, , V- to -R・I >0, (V/I) koji (
An arc or a short circuit may be determined by executing a calculation such as k/I)+R.

〔Effect of the invention〕

As explained above, the present invention allows the discrimination level to be changed with the welding current instead of being fixed.
In the low current range and high current range, the voltage during arcing and the voltage during short circuiting do not approach each other, so it is possible to accurately distinguish between short circuits and arcs, and the output operation of the welding power source can be adjusted according to short circuits and arcs. There is an advantage in that it is possible to reliably respond quickly and accurately send out an output suitable for the situation.

[Brief explanation of drawings]

Fig. 1 is a block diagram of an output control device for a welding power source embodying the present invention, Fig. 2 is a block diagram of a proportional element setting device in the above embodiment, and Figs. 3 and 4 show welding current-voltage characteristics and FIG. 3 is a diagram showing discrimination levels according to the invention. 1 - Welding power supply device, 2 - Power supply chip, 7 - Voltage detector, 8 - Current detector, 9 - Proportional element setter, 10 Constant number setter, 11 - Arithmetic unit, 12 - Comparison Vessel, 91-
-Welding wire diameter setting device, 92--Welding wire protrusion length setting device, 93- Welding wire material setting device, 94--Arithmetic unit.

Claims (3)

[Claims] (1) In consumable electrode arc welding with short circuit, using welding voltage V, welding current I, proportional element R, and constant k,
When the relationship >k+R×I holds true, it is determined to be an arc, and V<
A method for determining a short circuit/arc in consumable electrode type arc welding, characterized in that a short circuit is determined when the relationship k+R×I holds true. (2) A short circuit/arc discrimination method in consumable electrode type arc welding according to claim 1, wherein the proportional element is a resistance value of a protruding portion of a welding wire. (3) The resistance value is a value set by one or more of the wire diameter, material, and wire protrusion length. Arc determination method.