JPH0262017B2

JPH0262017B2 -

Info

Publication number: JPH0262017B2
Application number: JP58237045A
Authority: JP
Inventors: Tsuneo Mita
Original assignee: Hitachi Seiko Ltd
Current assignee: Via Mechanics Ltd
Priority date: 1983-12-15
Filing date: 1983-12-15
Publication date: 1990-12-21
Also published as: JPS60128340A

Description

[Detailed description of the invention]

〔発明の利用分野〕本発明はCO₂およびMAG溶接等の溶接作業性
を自動的、定量的に判定する方法に関する。〔発明の背景〕従来、CO₂溶接等の溶接作業性の良否は、一般
に熟練作業者が実際に溶接を行なつて判定してい
た。しかし、その判定は作業者自身の経験、技
量、好み等によつて決まる定性的なものであり、
優秀な作業者であればあるほどその判定は正しい
と言えるが、個人差があり、統一的な基準を求め
ることは不可能であつた。一方、溶接現象を高速
度カメラで撮影し、溶滴の移行状況、溶融池の動
き等を詳細に観察して溶接性の良否を判定する方
法もあるが、カメラの設置、フイルムの現像等、
準備や解析に相当な時間を要し、経費も高く、さ
らに得られる結果は必ずしも定量的なデータにな
るとは言えない欠点を有している。〔発明の目的〕本発明は、上記従来技術の欠点に鑑みなされた
もので、CO₂溶接等における溶接作業性の良否を
迅速に定量的に判定する方法を提供することにあ
る。〔発明の概要〕しかして本発明は、CO₂あるいはMAG溶接等
において、溶接電流と溶接電圧によつてアーク状
態の均一性の程度、アーク切れの程度およびアー
クの燃え上り度を算出し、これらの値を用いて溶
接作業性の良否を定量的に判定することを特徴と
するものである。〔発明の実施例〕一般にCO₂やMAG溶接は短絡とアークを繰り
返して溶接が実施される。第１図はその時の溶接
電圧波形と溶接電流波形を示したもので、T_Sは
短絡時間、T_aはアーク時間、Ｔは短絡から次の
短絡までの１周期、I_s.aveは短絡平均電流、I_a.ave
はアーク平均電流を示す。なお、I_s.ave，I_a.aveは
それぞれ短絡時間T_sおよびアーク時間T_aの電流
を矩形波に置き換えた場合の値である。このよう
に短絡とアークを繰り返す溶接の溶接性は、アー
ク状態の均一性、アーク切れ発生の程度およびア
ークの燃え上り度を総合して判定する必要があ
る。以下、これらの算出法について説明する。 CO₂溶接等に使用される電源は定電圧特性電源
で、出力電圧は制御されているが、電流、短絡／
アークの時間は、ワイヤ送給量等に応じて電源特
性・アーク特性の自己制御作用によつて決めら
れ、制御対象因子ではない。しかし、電流値、短
絡／アークの時間はアーク状態と密接な関係があ
り、これらの値の変動はアーク状態の変動、均一
性に大きな影響を与える。すなわち、アーク状態
の均一性は短絡時間T_s、アーク時間T_a、短絡平
均電流I_s.aveおよびアーク平均電流I_a.aveのバラツ
キ具合に関係し、簡便法として標準偏差を用いて
表わすことができる。これら４個の因子のうち、
どれか１つでもバラツキ標準偏差が大きくなれば
アーク状態の均一性は悪くなるから、４個の因子
は直列結合と考えられ、アークの均一性W_arcは
下記のように表わすことができる。 W_arc＝σ_TS・σ_Ta・σ_Is.ave・σ_Ia.ave (1) ここでσ_TS・σ_Ta・σ_Is.ave・σ_Ia.aveはそれぞれT_s，
T_a，I_s.ave，I_a.aveの標準偏差である。なお、短絡
とアークの区別は、アークから短絡、短絡からア
ークへの移行時に電圧は第１図のように急変する
ため、所定の電圧V_j（一般に10〜20V程度）より
電圧値が高いか低いかで、判別することができ
る。各電流値毎に最適電圧とされている電圧値で溶
接を行い、アーク期間中の平均抵抗値R_iを求める
と、第２図のように、シールドガス組成によつて
形状は変化するが、すべて溶接電流Ｉの２次式で
回帰でき下記のように表わされる。 R_i＝ａ・I²＋ｂ・Ｉ＋ｃ (2) こゝで定数ａ，ｂ，ｃは第１表のようである。
これらの定数はシールドガスにより変化するが、
機種、ワイヤ径が異なつてもほとんど変化しな
い。 [Field of Application of the Invention] The present invention relates to a method for automatically and quantitatively determining welding workability such as CO ₂ and MAG welding. [Background of the Invention] Conventionally, the quality of welding workability, such as CO ₂ welding, has generally been determined by a skilled worker actually performing the welding. However, the judgment is qualitative and depends on the worker's own experience, skill, preference, etc.
It can be said that the better the worker is, the more accurate his or her judgment will be, but individual differences exist, and it has been impossible to establish a uniform standard. On the other hand, there is a method of photographing the welding phenomenon with a high-speed camera and observing in detail the migration of droplets, movement of the molten pool, etc. to determine the quality of weldability.
It requires considerable time for preparation and analysis, is expensive, and has the disadvantage that the results obtained cannot necessarily be said to be quantitative data. [Object of the Invention] The present invention was made in view of the above-mentioned drawbacks of the prior art, and it is an object of the present invention to provide a method for quickly and quantitatively determining the quality of welding workability in CO ₂ welding and the like. [Summary of the Invention] Accordingly, the present invention calculates the degree of uniformity of the arc state, the degree of arc breakage, and the degree of burnout of the arc based on the welding current and welding voltage in CO ₂ or MAG welding, etc. This method is characterized in that the quality of welding workability is quantitatively determined using the value of . [Embodiments of the Invention] Generally, CO ₂ or MAG welding is performed by repeating short circuit and arc. Figure 1 shows the welding voltage waveform and welding current waveform at that time, where T _S is the short circuit time, T _a is the arc time, T is one cycle from one short circuit to the next, and I _s.ave is the short circuit average. Current, I _a.ave
indicates the arc average current. Note that I _s.ave and I _a.ave are values when the currents of short circuit time T _s and arc time T _a are replaced with rectangular waves, respectively. The weldability of welding in which short circuits and arcs repeat as described above needs to be judged by comprehensively considering the uniformity of the arc condition, the degree of arc breakage, and the degree of arc flare-up. These calculation methods will be explained below. The power supply used for _CO2 welding etc. is a constant voltage characteristic power supply, and the output voltage is controlled, but the current, short circuit /
The arc time is determined by the self-control of the power supply characteristics and arc characteristics in accordance with the wire feed rate, etc., and 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 related to the degree of variation in the short circuit time T _s , arc time T _a , short circuit average current I _s.ave , and arc average current I _a.ave , and can be expressed using standard deviation as a convenient method. Can be done. Of these four factors,
If the standard deviation of any one of them becomes large, the uniformity of the arc condition deteriorates, so the four factors are considered to be a series combination, and the arc uniformity W _arc can be expressed as follows. W _arc = σ _TS・σ _Ta・σ _Is.ave・σ _Ia.ave (1) Here, σ _TS・σ _Ta・σ _Is.ave・σ _Ia.ave are each T _s ，
This is the standard deviation of T _a , I _s.ave , and I _a.ave . The difference between a short circuit and an arc is that the voltage changes suddenly as shown in Figure 1 when transitioning from an arc to a short circuit or from _a short circuit to an arc. You can tell by how low it is. When welding is performed at the voltage value that is considered the optimum voltage for each current value and the average resistance value R _i during the arc period is determined, as shown in Figure 2, the shape changes depending on the shielding gas composition, but All can be regressed using a quadratic equation of the welding current I, and can be expressed as follows. R _i =a・I ² +b・I+c (2) Here, constants a, b, and c are as shown in Table 1.
These constants vary depending on the shielding gas, but
There is almost no change even if the model and wire diameter are different.

【表】抵抗値は電圧／電流で与えられる。CO₂溶接等
では定電圧特性電源を用いるため、電圧はほとん
ど変化せず、抵抗値の増加は電流の減少を意味す
る。溶接時のアーク期間中の平均抵抗値R_a.aveが
第２図に示したR_iの値より大きいほど電流値が低
く、ワイヤ溶融不足を示し、アーク切れを生じ易
い事を意味する。よつて、アーク切れ発生の程度
W_Rは下記のように表わせる。 W_R＝R_a.ave／（aI²＋bI＋ｃ） (3) なお、W_R＜１の場合、すなわち、溶接中の
R_a.aveが第２図のR_iより小さい場合はアーク切れ
を考慮する必要がないため、W_R＝１とする。 R_iと同様に、最適条件におけるアーク期間中の
電力P_iを求めると、第３図のようである。この場
合、シールドガスによつて形状は変化するが、す
べて下記の式で回帰できる。 P_i＝ｈ・e^g [Table] Resistance value is given as voltage/current. Since a constant voltage power source is used in CO ₂ welding, etc., the voltage hardly changes, and an increase in resistance means a decrease in current. The larger the average resistance value R _a.ave during the arc period during welding is than the value of R _i shown in FIG. 2, 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
W _R can be expressed as below. W _R = R _a.ave / (aI ² + bI + c) (3) In addition, when W _R <1, that is, during welding
If R _a.ave is smaller than R _i in Figure 2, there is no need to consider arc breakage, so W _R =1. Similarly to R _i , the power P _i during the arcing period under optimal conditions is determined as shown in FIG. In this case, the shape changes depending on the shielding gas, but all can be regressed using the following equation. P _i = h・e ^g

Claims

[Claims] 1. In arc welding in which welding is performed by repeating short circuits and arcs, welding voltage and welding current are detected at predetermined sampling intervals, and the short circuit time, arc time, short circuit average current, Calculate the arc average current, arc average resistance and arc power,
The short circuit time, arc time, short circuit average current, and arc average current are used to represent the degree of uniformity of the arc condition, the arc average resistance is used to represent the degree of arc breakage, and the arc power is used to represent the degree of arc burnout. A method for determining weldability, characterized in that the quality of weldability is determined based on the degree of uniformity of arc conditions, the degree of arc breakage, and the degree of arc flare-up. 2 The degree of uniformity of the arc condition is determined by the standard deviation of the short circuit time σ _TS , the standard deviation of the arc time σ _Ta , the standard deviation of the average value of the current during the short circuit period σ _IS.ave , and the average value of the current during the arc period. The weldability determination method according to claim 1, characterized in that the standard deviation of the values is expressed using σ _IS.ave . 3 The degree of uniformity of the arc state is expressed as σ _TS ,
The weldability determination method according to claim 1 or 2, characterized in that the weldability determination method is expressed as a product of σ _Ta , σ _IS.ave , and σ _IS.ave . 4 The degree of uniformity of the arc state is expressed as σ _TS ,
Claim 1 or 2 characterized in that it is expressed as the product W _arc of σ _Ta , σ _IS.ave and σ _IS.ave and the value K quotient (W _arc /K) of W _arc under predetermined standard welding conditions. Described weldability determination method. 5 The degree of arc breakage is determined by the quotient of the average resistance R _a.ave during the arc period and the value R _i of R _a.ave when welding at the optimum voltage for each current (R _a.ave / R _i ) The method for determining weldability according to claim 1. 6 The above R _i is expressed as the quadratic expression of the welding current I (R _i =aI ² +bI
The weldability determination method according to claim 5, characterized in that the weldability determination method is expressed as +c). 7. A patent characterized in that the degree of burning of the arc is expressed as the quotient (P _a /P _i ) of the electric power P _a during the arcing period and the value P _i of P _a when welding is performed at the optimum voltage for each current. A method for determining weldability according to claim 1. 8. The weldability determining method according to claim 7, characterized in that the P _i is expressed as an exponential function of the welding current I (P _i =h·e ^gI ) with the base being a natural number e. 9 The above weldability W is expressed as W=σ _TS・σ _Ta・σ _IS.ave・σ _Ia.ave /K・(R _a.ave /R _i ) ² ·P _a /P _i The method for determining weldability according to claims 2 to 8, characterized in that the weldability determination method is expressed as: /R i ) 2·P a /P i. 10 The above weldability W is expressed as W=-LN(K)+LN (σ _TS・σ _Ta・σ _IS.ave・σ _Ia.ave )+2LN (R _a.ave /R _i )+LN(P _a /P _i ) The weldability determining method according to any one of claims 2 to 8, characterized in that: