JPS60128340A - Deciding method of weldability in arc welding - Google Patents

Abstract

PURPOSE:To make a speedy and quantitative decision on whether welding operativity is normal or not by calculating the degree of the uniformity of an arc state, etc., from a welding current and a welding voltage, and deciding whether the welding operativity is normal or not by using said value. CONSTITUTION:A prescribed voltage is applied between a wire 2 and a base material 4 during welding by a welding power source 1 which has constant voltage characteristics, and the wire 2 is fed by a roller 3 at a prescribed speed so as to weld the base material 4. Then, the welding current is led out by a shunt 5 and supplied to a voltage detector 7, a current detector 8, and an A/D converter 9 which converts outputs of the detectors 7 and 8 into digital data. Further, this current is supplied to the decision device 6 consisting of a central processor 10 which performs various arithmetics for calculating a weldability index W and controls respective parts, display device 11 and printer 12, memory 13, and keyboard 14 for inputting data such as a constant necessary for measurement. Then, the uniformity of an arc state, degree abnormal condition of arc welding, and combustion extent of an arc are calculated from the measured welding current and voltage, and those values are used to decide on whether the welding operativity is normal or not quantitatively.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a method for automatically and quantitatively determining welding workability such as CO2 and MAσ welding.

[Background of the invention]

Conventionally, the quality of welding workability, such as 002 welding, has generally been determined by a skilled worker actually performing the welding. but,
The judgment is a qualitative one determined by the worker's own skill, preference, etc., and the better the worker, the more correct the judgment, but there are individual differences, and there is no uniform standard. It was impossible to get it. On the other hand, there is a method of photographing the welding phenomenon with a high-speed camera and closely observing the transfer status of droplets, movement of the molten pool, etc. to judge the quality of weldability. etc., it requires a considerable amount of time for preparation and analysis, is expensive, and has the drawback that the results obtained cannot necessarily be said to be quantitative data.

[Purpose of the invention]

The present invention has been made in view of the runner-up problems of the prior art described above,
The object of the present invention is to provide a method for quickly and quantitatively determining the quality of welding workability in CO, welding, etc.

[Summary of the invention]

Therefore, the present invention calculates the degree of uniformity of the arc condition, the degree of arc breakage, and the degree of arc flare-up by welding current and welding voltage in C02 or MAG welding, etc., and uses these values to improve welding workability. It is characterized by quantitatively determining the quality of the product.

[Embodiments of the invention]

Generally, CO2 or MAG welding is performed by repeating short circuit and arc. Diagram 1 shows the welding voltage waveform and welding current waveform at that time, where T is the short circuit time, Tt is the arc time, and ! is one station period from one short circuit to the next short circuit, ",
-mV@ indicates short circuit average current, and I@-awe indicates arc average current. In addition, Is, ay.・xa"ato is the short circuit time T and the current between Boo 24 and 24 is a rectangular wave, respectively.
This is the value when Icm is changed. In welding where short circuits and arcs repeat like this, weldability is determined by the uniformity of the arc condition,
It is necessary to comprehensively judge the extent of arc breakage and the degree of arc flare-up.

Below, these calculation methods will be explained.

002 The power supply used for welding, etc. is a constant voltage power supply, and the output voltage is controlled, but the current, short circuit/arc time, etc. are controlled by the self-control of the power supply characteristics and arc characteristics depending on the wire feed rate, etc. It is not a controlled factor.

However, the current value and the short circuit/arc time are closely related to the arc condition, and fluctuations in these values have a large effect on the variation and uniformity of the arc condition. In other words, the uniformity of the arc condition is determined by the short circuit time T, the arc time Ta, the short circuit average current If the standard deviation of any one of these four factors increases, the uniformity of the arc condition deteriorates, so the four factors can be considered as a series combination, and the uniformity of the arc 'arc can be expressed as follows.

"are"'? s"Ta"Es5ays"Xa*a
vs ”' ・Here a σ7.σ?a # 'Xm, aw
e "fat ato is T, ,T, respectively.

Is"ave" is the standard deviation of 1a-awe. In addition,
The difference between a short circuit and an arc is that the voltage changes suddenly as shown in Figure 1 when transitioning from arc to short circuit, short circuit to earth, and then to ri.
It can be determined whether the voltage value is higher or lower than a predetermined voltage V (generally about 10 to 20 V).

Welding is performed at the voltage value that is considered the optimum voltage for each current value, and the average resistance value R1 during the arc period is calculated.The shape changes depending on the shield gas composition, but all welding It can be regressed using the electrician's quadratic equation and is expressed as 5 below: R, == ll*

These constants vary depending on the shielding gas, but depending on the model,
There is almost no change even if the wire diameter is different.

Table 1 Resistance values are given in terms of voltage/current. aO2O2 welding wire Since a constant voltage characteristic power source is used, the voltage hardly changes,
An increase in resistance means a decrease in current. The average resistance value Ra'ave during the arc period during welding is shown in Figure 2.
The larger the value, the lower the current value, which indicates insufficient wire melting and means that arc breakage is likely to occur. Therefore, the degree of arc breakage WR can be expressed as follows.

"R=--av./(aI + bl + O) (3
1-Note that when W, <1, that is, Ra during welding
``If ave is smaller than Ri of the second cape, there is no need to consider arc breakage, so WR=1.

If we take K as well as Ri and the power Pi during the arcing period under the optimum conditions, we get the result as shown in Fig. 3. In this case, the shape changes depending on the shielding gas, but all can be regressed using the following formula.

PlWh..."I(4) The constants g and h are 5 as shown in Table 2. These constants vary depending on the shielding gas, but as in the case of R□, it depends on the model,
Even if the wire diameter is different, there is almost no difference.

The power Pa during the arcing period in Table 2 is a factor related to the generation and growth of droplets that transfer to the molten pool due to short circuits. , means excessive melting, and means that arc is likely to flare up. J, the degree of burnout of the arc, W, can be expressed as follows. -w, =p, /(h...g,")
, (5) Note that w, <1, that is, P during welding
If , is smaller than Pi in Figure 3, there is no need to consider arc flare-up, so! , = 1.

The larger the value of any one of the Ware "11" P values set as above, the worse the weldability becomes. Therefore, these factors are considered to be a series combination, and the value indicating weldability (weldability index) W is as follows.

” “aro)a(WR)β” (WP) r(6
) However, α, β, and r are constants that weight each factor.

A certain standard welding condition, for example, a condition that is said to show the best weldability in CO welding of φ1.2 wire (welding current 1
50A, welding voltage of about 19V) is taken as a constant, and W miW /K (7) m art , then the constants α, β, r in equation (6) is simplified and W
can be expressed as below.

-=W,・(W,)”・w, (8) Since the value of W above shows an extremely large difference between the minimum value and the maximum value, the right side is expressed logarithmically and it is set to 5 as shown below. , which is more practical.

w=bi(wA)+2-hN(wR)+LN(w,)
Expressing the formula for calculating W with (e) using form data, we get
It will look like this:

we=-+LH (σT,) + L N (σ, &)
+LN(σXs, ave>”LNCσIa, ave)+
2.1aHCR@, lLv. /R,)+LH(P,/P
, ) a1 However, k=-LN(Kl).

In Figures 4 to 7, k = 7.95, R,"l: 5
,55 X1O-6-12-5,15X 10-'・x
+o, s s s, P engineering; 1.7-9・eO, 01a
-X, and the welding currents are 15OA, 200μ, and 2, respectively.
00 of φ1.2 wire with setting to 50A and 300
These are the results of calculating the weldability index W using Masu Ni when two welds were performed and the welding voltage was varied. In the figure, the four types of symbols indicate different models.1. This shows that the results are for four types of welding power sources.6 For all models and current values, the W value forms a curve with a downwardly convex minimum value, and the voltage value that shows the minimum value is the best. This corresponds to the voltage value that provides the best weldability, that is, the optimum voltage.

Figure 8 shows the optimum voltage for each current with a φ1.2 wire,
This is the value of W when 0□ welding is performed. W at 160A, which is said to show the best weldability with φ1.2 wire.
shows the smallest value, and the short arc welding area near it shows the lowest value. The area near 220A, where the droplet transfer becomes a four-branch transfer, is the area where weldability is said to be the worst (+-7) in 002 welding of φ1.2 wire due to arc flare-up, large amount of spatter, etc.
The value of W is also large. The vicinity of 300A is a region where the droplet transitions from one to the other, and is considered to be a region where weldability is relatively improved. Also in FIG. 8, the W of 300 mm is smaller than the value of 220 to 250 A'. In this way, changes in workability depending on the current value can also be expressed using the value of W. Furthermore, differences between models can be expressed by the value of W, and it can be seen that models with a small value of W and models with a high evaluation of weldability are the same. - Figure jI9 shows the results of CO2 welding of φ0.9 wire at 100 μm, but in the case of φ1.2 wire, the voltage that minimizes the value of W and the best weldability are determined as in the case of □. The voltages shown match.

Figure 10 and #! Figure 11 shows welding currents of 130 A and 130 A, respectively, using a φ1.2 wire and changing the shield gas composition.
This is the value of W when welding is performed at 25OA. As in the case of CO2 welding, the value of W forms a downwardly convex curve, and its minimum value coincides with the voltage value indicating optimal weldability. Also C0
It is said that the weldability improves as the amount of Ar added to 2 increases, but in Figures 10 and 11, the minimum W value is low, and a low W value indicates good welding. Consistent with the meaning of gender.

Figure 12 shows the value of W when welding was performed at the optimum voltage for each current by changing the shielding gas composition using the same φ1.2 wire, and it shows the same tendency as Figures 10 and 11. show.

As mentioned above, the value of W calculated by the formula is a unified index that indicates weldability even if the model, shielding gas, and wire diameter change, and a small value means good weldability. . That is, the quality of weldability can be quantitatively determined by W.

FIG. 13 is a block diagram of one embodiment of the present invention. In the figure, a welding power source 1 has constant voltage characteristics and applies a predetermined voltage to a wire 2 and four base materials. In order to weld the base metal 4, the wire 2 is fed at a predetermined speed by a feed μm feeder 3. The welding current is proportional to y to the feed speed of the wire 2.

Although not shown in the figure, there is a torch at the tip of the wire 2, so that K Co or MAG gas is ejected as the wire is fed. 5 is a current shunt for measuring the welding current, and 6 is a calculation and output device for the weldability index W, which is the center of the present invention. The device 6 includes a voltage detector 7 and a current detector 8 for measuring welding voltage and welding current and amplifying them to a predetermined level, and an analog device for converting the outputs of the voltage detector 7 and the current detector 8 into digital data. Digital (A
/D) Converter 9, central processing unit (opυ) 10 that performs various calculations for calculating the weldability index W and controls each part.
, a line 5 display 11 and a printer 12 for displaying and printing out the weldability index as necessary, a memory 13 for storing various data necessary for calculations and calculations, constants necessary for measurement, and other data. It consists of a keyboard 14 for input.

The first outline process 7p- of the weldability index calculation and output device 6
Shown in Figure 4. First, the number of data N required to calculate the weldability index W, the short circuit/arc judgment voltage Vt, and the sampling interval S for current/voltage measurement are input from the keyboard 14 and set in a predetermined register in 0Pυ10 (step 101 ). If the sampling interval B is short, accurate data can be obtained, but if the welding current is 220A or less, 0.
It may be about 1 Ila, and about 0.2!18 for 220A or more. It is better to take a long time to measure welding voltage and welding current, but if the welding current is less than 220m, it will be around 0.58, 2
For 20A or more, it should be about 18, so the number of data N
is below 220 μm, N=0.5X100010.1=
5000 220A or more, N=1×100010.
2 to 5,000, and even if K is added, it should be about M-5,000.

The short circuit/arc judgment voltage V may be set to about 10 V for the entire current range, but if it exceeds 200 A, a very short instantaneous short circuit will occur. It is good to wash with the setting set to .

! When ≦200A, Vj = 10 V 2O0A (When 1≦250m, Vj = 1 5 Vl)2
At 50 A, Vj = 20 V N , V, , After setting a is completed, welding conditions (voltage, current, shielding gas, etc.) are set and welding is started (step 102). And sampling point 1
= 0 (step 105), the output of the A/D converter 9 at that time, that is, the welding current data I (0) and the welding voltage data V (OJ of the sampling point (0))
(step 104), and stores it in the memory 13, for example, at address 0 (step 105). After that, it is determined whether 1 or N (step 1o6), and if it is ygs, it is set as iel (step 107), and after S time, the sampling point (
1) welding current data I(1) and welding voltage data v(
1) is input and stored in memory 150 address 1. i(a
The same operation is repeated for S time intervals, and the welding current data X(1) and welding voltage data V(iJ) of each sampling point (11) are stored one after another at address 130 in the memory.

When sampling of a predetermined number of welding current data and welding voltage data is completed, first, v(1) is compared with V, and each short circuit starting point s(p) and arc open M point (R) are determined (step 108). Figure 20 shows short circuit starting point 8 (R),
This shows the arc starting point (R1).

Waveform data for each cycle using the next K 8 (R1, T(R), I(1) and v(1), that is, short circuit time A (P
) (?, in Figure 1), arc time B (P) (1st
T&) in the figure, short circuit average current 0 (P) (xs*a in Figure 1
va ), arc average current D (Pl (Ia in Fig. 1)
'ave ), arc average resistance B(P) (R of equation (3)
a”ave), arc power F(PJ (p in equation (5),
) (step 109), their average value mu a#
'b, Ao"1'm., Af are calculated (step 11
0).

Then A (Pi, B (Pl, 0(PJ, D(P)K
'Then, A,, A, $A0. Using AD, its standard deviation G1L, Gb, G0. G. (Step 111)
). Next, G, Gb, Go, G, which was claimed in this way,
A weldability index W is calculated using A, ,A, and A (step 112). The calculated weldability index W is displayed on the display 11, and is also output to the printer 12 if necessary (step 113).

Next, it is determined in step 11 whether there is an instruction to continue reducing W for other welding conditions. If so, the welding conditions are reset and the operations from step 103 onwards are repeated. On the other hand, if W is not to be calculated continuously, welding is stopped and the process is ended (step 115).
.

FIG. 15 shows details of the subroutine for performing short circuit/arc determination in step 108 in FIG. 11g14. In FIG. 15, the process begins by setting the short circuit starting point T (■. First, after setting 1; 0, R=O (steps 201, 202), the first short circuit point (0 ) welding voltage data v(01 is read out, v,
(step 203). And v(o)>v
, then go to step 206, but if v(o)≦V, set 1 to 1 (step 204), read out V (1) at the next sampling point (1), and set V. Compare (step 205). v(11≦V, the processes of steps 204 and 205 are repeated. From FIG. 20, V
(iJ≦V means a short terminal period. When V(phantom>v), determine i(u as 1; 1+1. Step 2o
6゜zo7), if i>N, the corresponding broutine processing is terminated, but if i(u), V(reads the illusion and returns v
(1)>V is determined (20B). And v(1)
〉■, the processes of steps 206 to 20B are repeated. From FIG. 20, v (u > V* means arc period. Repeat steps 206 to 208.
When v(phantom≦V, that point means the short circuit starting point 8(11). This sampling point (phantom) corresponding to 8(R1) is stored in a predetermined location in the memory 130 (step 209).
. Next, let i=i+1 and determine i(n. Step 2
10, 211), i) If N, the subroutine process ends; if i(H), read V(1) and determine whether v(1)≦V (212). V(i
If J≦V, the processes of steps 210 to 212 are repeated. In this way, when V (1) > V, K, that point becomes the arc starting point T (meaning RJ. The sampling point (1) corresponding to this T (RJ) is stored in the memory 13 (213). After that , R=1-1-[by closing (step 214) and repeating the filling after step 206, 8(RJ, T(B) are filled one after another. Then, i)
When the signal becomes H, the subroutine processing ends.

FIG. 16 shows details of the subroutine in step 1090 in FIG. 14 for calculating and filling in waveform data. In Figure 16, s (p), T (PJ is 8 (R
J, T (' has the same meaning as EO. First, p = o (step 301), then the difference U (8) between the arc starting point T (P) and the short circuit starting point s (P), the short circuit starting point 8 (P+1
) and the arc starting point T (P) are calculated (steps 502, 505). That is, u (s) is T
From K, taking the difference between the sampling point of (P) and the sampling point of s (p), and U (A) is 8(P+1
Calculate the difference between the sampling point of T (PJ) and the sampling point of T (PJ) from K. Next, calculate the short circuit time A (P) by multiplying %U (83 by sampling interval B). Similarly, the arc time B (PJ) is calculated by multiplying by the sampling interval 8 (step 305).

As a result, A(pJ s B(
When P) is fixed, it becomes K. Next, in this period, short circuit average current 0 (PJ, arc average current D (19, arc average resistance x (PJ, arc power F I (kJ (= X (1)) and u (
s) to calculate c(p).Step 306), T
(P) ~s (p +1) between I (k) (= 1
Calculate D(PJ) using (illusion) and υ(A) (
Step 3o7).

Also, V(k) (
= v (i) ), I (k) (=
between vlkl(= V(iJ) tI(kJ(= I(
1) Oyohi? Calculate F (PJ) using the y pulling interval S (step 309). Then, set p = p - z (step 310), and determine P (H (step 3).
11), if P≧R, the processing of the routine ends, but if it is PAR, the processing from step 302 onwards is repeated, and A(PJ, B (PJ, c(p), D
(P), B (P), F (Put on PJ.

FIG. 17 shows details of the subroutine for performing the average value calculation process in step 110 in FIG. 14.

The average value Aa of the short circuit time is the short circuit time A (r
) (= A (PJ ), and calculate it as the number of data P
It is obtained by dividing by k (step 401). Similarly, average value A5 of arc time B (r) (''= B (PJ ), short circuit average current 0 (r) (= O(P)
) average value A0, arc average current D(r) (= average value Aa of D (taku), arc average resistance K (rJ (W
(P) ) average value A0, arc power F (rJ (
= F (P) ) is sequentially calculated (steps 402 to 407).

#! FIG. 18 shows a subroutine for calculating the standard deviation in step 111 in FIG. 14. That is, by substituting the data obtained in Figures 16 and 17 into the general calculation formula for standard deviation, the standard deviations of short circuit time, arc time, short circuit average current, and arc average current are calculated, respectively.
), G, (=σTa), Go(=σl5ave), G
Calculate e1 (=σIa”aY6) (step 50
1-504).

FIG. 1819 is a subroutine for performing the weldability index calculation process of step 112 in FIG.

R, , Pi in FIG. 19 are respectively R, L, av
. ,P.

These are the values of regression equations (2) and (4). First, G, Gbs
The arc uniformity WA is determined using Go and G6 (step 601), and the degree of arc breakage occurrence WR is determined using K A, , Ri (step 602). Next, it is determined whether WR(O) (step 6oa), and if wR>o, the process immediately goes to step 605, but if wR<0, WR=
After setting it to O (step 604), the process goes to step 605. In step 605, the arc burn-up degree W is calculated using A and 4. Next step 60 to determine kcwP<0
6), if wP<7, set W, = O (step 607). The weldability index W is calculated using WA#WR,W determined in this way (step 608).

〔Effect of the invention〕

As described above, according to the present invention, the following effects can be obtained.

(Sumire) Weldability, which was previously understood qualitatively, can now be understood quantitatively.

(2) Even beginners can grasp weldability, which could not be grasped without considerable experience and skill.

(3) Weldability, which has been perceived to be somewhat distorted depending on the skill and preference of the worker or the working environment and conditions, can be expressed as a unified numerical value, and does not include differences due to individual differences, environmental influences, etc.

(4) Even beginners can easily set the optimal welding conditions, which previously required experience and skill, by referring to the values obtained in the present invention.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram of current and voltage waveforms in arc welding, Figure 2 is an explanatory diagram of arc average resistance, Figure #I5 is an explanatory diagram of arc power, and Figures 4 to 12 are explanatory diagrams of weldability index. , 1st
Figure 5 is a diagram of one embodiment of the present invention, and Figure 14 is #1.
Figure 13 shows the entire 7 in one diagram, Figure 15 shows the short-circuit/arc judgment, Figure 16 shows the waveform data calculation process, and Figure 17 shows the waveform data. Figure 70 shows the average value calculation process, Figure 18 shows the standard deviation calculation process for waveform data, and Figure 19 shows the weldability index calculation process.
The μ-diagram and FIG. 20 are explanatory diagrams of the short-circuit starting point and the arc starting point. 1... Welding power source, 2... Wire, 3... Feed μm
4... Base metal, 5... Shunt switch, 6... Weldability index calculation and output device, 7... Voltage detector, 8... Current detector, 9... A/ D converter, 1o...ap
u, display, 12... printer, 15...
Memory, 14...Keyboard. Layer #Area r Figure 3 yh # Definite AI Figure 4 5F-Stirring fang 5 Figure jR-I (Haishin offering frc :g!- Offering table 12th encyclopedia #Ft charge 13 Figure 14 figure

Claims (1)

[Claims] (1) Welding is performed by repeating short circuit and arc.
Arc melting! In I, the welding voltage and welding current are detected at a predetermined sampling interval, and the short circuit time, arc time, short circuit average current, arc average current, arc average resistance, and arc power for each cycle are calculated, and these data are A method for determining weldability, characterized in that the degree of uniformity of the arc state, the degree of arc breakage, and the degree of arc burn-up are determined by integrating these factors to determine the weldability. (2) The degree of uniformity of the arc state is expressed as the standard deviation of the short circuit time σT, the standard deviation of the arc time σ'ff'a,
The standard deviation of the average value of the current during the short circuit period σ;awe and the standard deviation of the average value of the current during the arc period σXa,a
Claims characterized in that they are expressed using ve (
Weldability determination method described in section 1). (3) The degree of uniformity of the arc state is expressed as σTs'σ
Claims (1) and (1) are expressed as the product of 7°σIa, ave and σ□a'ave;
Weldability determination method described in section 2). (4) The degree of uniformity of the arc state is determined by the product of σa, s, σaeaV@, and σX, 1.7° and the predetermined standard welding conditions/) of the value of X of W, . A method for determining weldability according to claims (1) and C'2), characterized in that the weldability is expressed as a quotient (W/x). (5) The degree of arc breakage is determined by the arc period. (6) The degree of arc breakage is expressed using Ra-awe and the optimum value for each current. The weldability determination method according to claim (6), characterized in that the value of Ra'av when the voltage is applied is expressed as the quotient (R, L, 1v0/Ri). (7) The quadratic equation of the welding current I (R1==1
The weldability determination method according to claim (6), characterized in that the weldability determination method is expressed as LI20bx +o). (8) The weldability determining method according to claim (1), wherein the degree of burnout of the arc is expressed using electric power P1 during the arcing period. (9) The degree of burnout of the front arc is determined by the value of Pl when welding at the optimum pressure for each current.
The method for determining weldability according to claim (8), characterized in that the weldability is expressed as Pi). a. The weldability determination method according to claim (9), characterized in that P1 is expressed as an exponential function of welding current machining (P = h - ej) with the base being a natural number e. A method for determining weldability according to claim 2, characterized in that the weldability W is expressed as !=-LN(K)+LH(σTs・σT1・σIs *
a'v.・σIa, ava)”2 La (Ra-av
e /R1)''LN (P a/p1 ) (The weldability determination method described in Gen to Masu).