JPH037471B2 - - Google Patents
Info
- Publication number
- JPH037471B2 JPH037471B2 JP59177981A JP17798184A JPH037471B2 JP H037471 B2 JPH037471 B2 JP H037471B2 JP 59177981 A JP59177981 A JP 59177981A JP 17798184 A JP17798184 A JP 17798184A JP H037471 B2 JPH037471 B2 JP H037471B2
- Authority
- JP
- Japan
- Prior art keywords
- plasma
- flow rate
- working gas
- arc
- welding
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Classifications
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
- H05H1/00—Generating plasma; Handling plasma
- H05H1/24—Generating plasma
- H05H1/26—Plasma torches
- H05H1/32—Plasma torches using an arc
- H05H1/34—Details, e.g. electrodes, nozzles
- H05H1/36—Circuit arrangements
Landscapes
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Plasma & Fusion (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Arc Welding Control (AREA)
Description
【発明の詳細な説明】
（産業上の利用分野）
本発明は、プラズマ溶接、溶断、熱処理等のプ
ラズマ加工におけるプラズマアークの効率的な起
動方法に関する。DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an efficient method for starting a plasma arc in plasma processing such as plasma welding, cutting, heat treatment, etc.
（従来の技術とその問題点）
以下プラズマ溶接を例にとつて説明する。一般
にプラズマアーク溶接方法ではアークの起動時に
高周波放電により電極−ノズル間にパイロツトア
ークを発生させ、これに伴うノズルからの噴出プ
ラズマ（プラズマジエツト）の導電性を利用し
て、電極−母材間にプラズマアークを発生させて
溶接を開始する。従来、プラズマアークを電極−
母材間に発生させる手段としては、
トーチのノズル部分にプラズマジエツトを発
生させてからトーチ自身を母材に接近させ、プ
ラズマジエツトを母材に接触させて電極−母材
間にプラズマアークを発生させ、しかる後トー
チを母材から適宜距離だけ離す。(Prior art and its problems) The following will explain plasma welding as an example. Generally, in the plasma arc welding method, a pilot arc is generated between the electrode and the nozzle by high-frequency discharge when the arc is started, and the conductivity of the accompanying plasma (plasma jet) ejected from the nozzle is used to create a pilot arc between the electrode and the base metal. A plasma arc is generated to start welding. Conventionally, plasma arc was used as an electrode.
The method for generating plasma between the base metals is to generate a plasma jet at the nozzle of the torch, then bring the torch itself close to the base metal, bring the plasma jet into contact with the base metal, and create a plasma arc between the electrode and the base metal. is generated, and then the torch is separated from the base material by an appropriate distance.
パイロツトアーク電流を大にしてプラズマジ
エツト長を伸長させ母材に接触させる（特開昭
55−97874）。 The pilot arc current is increased to extend the plasma jet length and bring it into contact with the base metal (Unexamined Japanese Patent Publication No.
55−97874).
発生したプラズマジエツトの外周に制御ガス
を層流状態で流し、これによりプラズマジエツ
ト長を伸長させ母材に接触させる（特開昭49−
11743）。 A control gas is flowed in a laminar flow around the outer circumference of the generated plasma jet, thereby extending the length of the plasma jet and bringing it into contact with the base material (Japanese Patent Application Laid-Open No. 1989-1999).
11743).
等があるがいずれも実際的ではない。すなわち
はトーチと母材間との距離を可変にする必要があ
り、従つて装置が複雑で操作に手間どるという欠
点があり、、はトーチと母材間の距離は一定
でよいが、ではノズル内の温度上昇に主に貢献
するだけで肝心のプラズマジエツト長は目的を達
する程伸びず、ではノズル外の気圧はノズル内
の気圧より低下してプラズマが引き出され、プラ
ズマジエツトが伸びるのである程度の効果はある
ものの、確実性に欠ける欠点があり、又制御ガス
用の通路をトーチに設けなければならないのでト
ーチは作動ガス用、制御ガス用、シールドガス用
の３通路を備えることになり、構造が複雑にな
る。第４図ａ，ｂはプラズマジエツトの形成状態
を示した図でａ図はアークＰの陽極点がノズル３
の挾搾部にある良好な状態のパイロツトアークＰ
の場合でこの場合プラズマジエツトＪの伸びも良
い。ところがｂ図のようにノズル３の消耗等でア
ークP′の陽極点がノズル３の内部の引つ込んだ位
置に移ることがしばしばあり、このような場合に
はプラズマジエツトJ′も引つ込んだ伸びの悪い状
態となる。プラズマジエツトがｂ図の状態を呈す
ると上記手段、はほとんど効果がない。この
ように従来のプラズマアークの起動方法はいずれ
も簡易性、確実性に欠けていた。etc., but none of them are practical. In other words, it is necessary to vary the distance between the torch and the base material, which has the disadvantage that the device is complicated and takes time to operate. This mainly contributes to the rise in temperature inside the nozzle, and the critical plasma jet length does not extend enough to achieve the desired goal.In this case, the air pressure outside the nozzle becomes lower than the air pressure inside the nozzle, and the plasma is drawn out, causing the plasma jet to extend. Although it is effective to some extent, it has the drawback of lacking reliability, and since a passage for the control gas must be provided in the torch, the torch has three passages for working gas, control gas, and shielding gas. , the structure becomes complicated. Figures 4a and 4b are diagrams showing the formation state of the plasma jet, and in figure a, the anode point of the arc P is at the nozzle 3.
Pilot arc P in good condition in the squeeze part of
In this case, the elongation of the plasma jet J is also good. However, as shown in Figure b, due to wear and tear of the nozzle 3, the anode point of the arc P' often moves to a retracted position inside the nozzle 3, and in such cases, the plasma jet J' is also withdrawn. This results in a state where the growth is poor. When the plasma jet exhibits the state shown in Figure b, the above measures have little effect. As described above, all conventional plasma arc starting methods lack simplicity and reliability.
（発明の目的）
本発明は上記従来の欠点を解消するものであ
り、始動時にノズル先端に発生した短小のプラズ
マジエツトをノズル前方に押し出し、確実に電極
−母材間にプラズマアークを発生させる方法を提
供することを目的とする。(Objective of the Invention) The present invention solves the above-mentioned conventional drawbacks by pushing out a short and small plasma jet generated at the tip of the nozzle at the time of startup to the front of the nozzle, thereby reliably generating a plasma arc between the electrode and the base material. The purpose is to provide a method.
（問題点を解決するための手段・作用）
この目的を達成する本発明のプラズマアークの
起動方法の要旨とするところは、起動時の作動ガ
ス流量を加工時よりも大にしてプラズマジエツト
長を伸ばし、母材に接触させ、電極−母材間にプ
ラズマアークを発生させることにある。以下プラ
ズマ溶接を例にとつて説明する。通常、溶接中の
定常状態における作動ガス流量は溶接条件によつ
て決定され、その流量は多くの場合少流量（例え
ば0.2〜1.0／min）であり、この流量ではプラ
ズマジエツトをノズル先端からわずかに突出させ
るだけの圧力しか得られない。本発明ではアーク
起動時にプラズマジエツトがノズル先端より充分
長く伸びるように作動ガス流量を起動時のみ多く
（例えば1.5〜3.0／min、：1.5／minに満たな
いというプラズマジエツトの押し出し効果が弱
く、3.0／minを超えるとパイロツトマークの
維持が困難となる）する。この起動時の作動ガス
流量は溶接時の作動ガス流量の２倍以上が必要で
ある。すなわち一時的に多量の作動ガスをを流す
ことにより、該ガスの圧力で強制的にプラズマジ
エツトはノズルから強く噴出する。これによりプ
ラズマジエツトが伸びてその先端が母材接触し、
プラズマアークの起動がなされる。そしてプラズ
マアークが発生したら直ちに作動ガス流量を少な
くし定常時の流量に戻す。この場合作動ガス流量
が定常時の流量になる迄の間の溶接電流つまりス
タート電流を定常時より小電流にして母材を溶融
しないようにしておくことが必要であり、これに
より溶融部をプラズマジエツトで吹きとばす不都
合を防止できる。(Means/effects for solving the problem) The gist of the plasma arc starting method of the present invention that achieves this purpose is to increase the plasma jet length by increasing the working gas flow rate during startup compared to that during machining. The purpose is to stretch the electrode, bring it into contact with the base material, and generate a plasma arc between the electrode and the base material. The following will explain plasma welding as an example. Normally, the working gas flow rate in the steady state during welding is determined by the welding conditions, and the flow rate is often a small flow rate (for example, 0.2 to 1.0/min), and at this flow rate, the plasma jet is moved slightly from the nozzle tip. You can only get enough pressure to make it stick out. In the present invention, the flow rate of the working gas is increased only at the time of starting the arc so that the plasma jet extends sufficiently longer than the nozzle tip (e.g., 1.5 to 3.0/min, the pushing effect of the plasma jet is weak, which is less than 1.5/min). , if it exceeds 3.0/min, it will be difficult to maintain the pilot mark). The working gas flow rate at the time of startup needs to be at least twice the working gas flow rate during welding. That is, by temporarily flowing a large amount of working gas, the pressure of the gas forces the plasma jet to be strongly ejected from the nozzle. This causes the plasma jet to extend and its tip to come into contact with the base material.
The plasma arc is activated. Immediately after a plasma arc occurs, the working gas flow rate is reduced to return to the normal flow rate. In this case, it is necessary to keep the welding current until the working gas flow rate reaches the steady state flow rate, that is, the start current, to be smaller than the steady state current to prevent the base metal from melting. You can prevent the inconvenience of blowing it off with a jet.
このような本発明のプラズマアークの起動方法
によれば始動時のプラズマジエツトの形成状態
（第４図に示した）にかかわらず確実にプラズマ
ジエツトが伸びてプラズマアークを起動させるこ
とができる。すなわち第４図ｂの状態であつても
作動ガス流量の圧力でパイロツトアークの陽極点
はノズル狭搾部に移行し、第４図ａの状態の良好
なプラズマジエツトが形成され、しかる後プラズ
マジエツトの充分なる伸長が始まるからである。 According to the plasma arc starting method of the present invention, the plasma jet is reliably extended and the plasma arc can be started regardless of the formation state of the plasma jet at the time of starting (as shown in FIG. 4). . That is, even in the state shown in Fig. 4b, the anode point of the pilot arc moves to the nozzle narrowing part due to the pressure of the working gas flow rate, and a good plasma jet in the state shown in Fig. 4a is formed, and then the plasma This is because the jet begins to fully expand.
（実施例）
次に本発明を図面に示す具体例により説明す
る。(Example) Next, the present invention will be explained using specific examples shown in the drawings.
第１図は本発明に係るプラズマアーク溶接機の
具体例を示す図で、第２図はその電気回路図、第
３図はタイムチヤートである。第１図において１
１はプラズマアークトーチで、該トーチ１１は電
極１、電極１を絶縁部を介して支持し、作動ガス
の通路となる内筒２、内筒２先端に取付けられた
水冷構造の挾搾ノズル３、シールドガス用の外筒
４からなる。５，６はそれぞれ作動ガス入口、シ
ールドガス入口を示す。電極１と挾搾ノズル３は
パイロツトアーク用電源９に接続され、また電極
１と母材８は溶接電源１０に接続される。１８は
溶接電流検出器を示す。２２は作動ガス供給制御
部で、電磁弁１４、流量調整弁１２と電磁弁１
５、流量調整弁１３を備え、これらが並列に作動
ガス入口５と作動ガスボンベ（図示せず）の間に
設けられている。 FIG. 1 is a diagram showing a specific example of a plasma arc welding machine according to the present invention, FIG. 2 is an electric circuit diagram thereof, and FIG. 3 is a time chart. In Figure 1, 1
Reference numeral 1 designates a plasma arc torch, and the torch 11 includes an electrode 1, an inner cylinder 2 that supports the electrode 1 through an insulating part, and serves as a passage for working gas, and a water-cooled squeeze nozzle 3 attached to the tip of the inner cylinder 2. , an outer cylinder 4 for shielding gas. 5 and 6 indicate a working gas inlet and a shielding gas inlet, respectively. The electrode 1 and the squeeze nozzle 3 are connected to a pilot arc power source 9, and the electrode 1 and the base material 8 are connected to a welding power source 10. 18 indicates a welding current detector. 22 is a working gas supply control unit, which includes a solenoid valve 14, a flow rate adjustment valve 12, and a solenoid valve 1.
5, a flow rate regulating valve 13 is provided in parallel between the working gas inlet 5 and the working gas cylinder (not shown).
溶接時においては作動ガスは電磁弁１４側を通
り、流量調整弁１２によつて調整される流量でト
ーチ１１内へと流入する。この流量は少流量例え
ば0.7／minであり、プラズマアークを起動す
ることはできない。そこで起動時のみ電磁弁１５
も電磁弁１４に併わせて開き、一時的に多量例え
ば2.0／minの作動ガスをトーチ１１内へ流入
させる。これにより前述のようにプラズマジエツ
トが伸びて母材に接触したプラズマアークが発生
して溶接開始となる。 During welding, the working gas passes through the electromagnetic valve 14 side and flows into the torch 11 at a flow rate adjusted by the flow rate adjustment valve 12. This flow rate is a small flow rate, for example, 0.7/min, and cannot start a plasma arc. Therefore, only when starting the solenoid valve 15
The solenoid valve 14 also opens to temporarily allow a large amount of working gas to flow into the torch 11 at a rate of, for example, 2.0/min. As a result, as described above, the plasma jet is extended and a plasma arc is generated that contacts the base metal, thereby starting welding.
第２図の電気回路、第３図のタイムチヤートに
より、この溶接動作をさらに説明する。第２図に
おいてＸ、Ｔ、SOL1、SOL2はリレー詳しくはそ
のコイルで、SOL1は電磁弁１４の開閉を、また
SOL2は電磁弁１５の開閉を行なう。Ｘ１，Ｘ２
はリレーＸの接点、Ａ１，Ａ２は溶接電流検出器
１８の接点、STは始動スイツチ、SPは停止スイ
ツチ、MSはメインスイツチである。第３図で
STは起動釦の動作タイミングを示し、Ｆはトー
チ１へ供給されるガスの流量のまたＩは溶接電流
の各時間変化を示す。 This welding operation will be further explained with reference to the electric circuit shown in FIG. 2 and the time chart shown in FIG. In Figure 2, X, T, SOL 1 , and SOL 2 are the relays, specifically their coils, and SOL 1 controls the opening and closing of the solenoid valve 14, and
SOL 2 opens and closes the solenoid valve 15. X1, X2
is a contact of relay X, A1 and A2 are contacts of welding current detector 18, ST is a start switch, SP is a stop switch, and MS is a main switch. In figure 3
ST indicates the operating timing of the start button, F indicates the flow rate of gas supplied to the torch 1, and I indicates the time change in the welding current.
作業者がメインスイツチMSを閉じるとリレー
SOL1が付勢されて電磁弁１４が開き、流量調整
弁１２によつて決まる少流量（Fw）の作動ガス
がトーチ１１内へ流れ始める（第３図ａ時点）。
次に始動スイツチSTを閉じるとMS、ST、SPの
経路でリレーＸが付勢されて自己保持用接点Ｘ１
を閉じ、また接点X2を閉じる。接点X2が閉じる
とこの段階では溶接電流検出器１８の常時閉接点
A1が閉じているので該接点を介してリレーSOL2
が付勢され電磁弁１５が開いて流量調整弁１３に
よつて決まる流量の作動ガスが流れ、電磁弁１４
を流れる作動ガスに合わさつて多量（Fs）の作
動ガスがトーチ１１内に流れる（第３図ｂ時点）。
流量Fsの作動ガスがトーチ１１へ流れるとプラ
ズマジエツト７が伸びてやがて母材８に接触しプ
ラズマアークが発生する、すなわちスタート電流
（Is）が流れ始める（第３図ｃ時点）。スタート電
流が流れ始めると溶接電流検出器１８により接点
A1が開いてリレーSOL2を消勢させ、これにより
電磁弁１５が閉じてトーチ１１へ流入する作動ガ
ス流量が減少する。同時に溶接電流検出器１８の
常時開接点A2が閉じ、溶接電流立上りタイミン
グ用のタイマーＴが付勢される。タイマーＴの設
定時間ｔは作動ガス流量が起動時の大流量Fsか
ら溶接時の流量Fwに移行するまでの時間であり
該時間ｔの経過後、図示しない溶接電流制御回路
が動作して所定値Iwへの溶接電流の増大を開始す
る（第３図ｄ時点）。このようにタイムラグを設
けて溶接電流Iwを流すのは、前記の如く作動ガス
が多量に流れている状態でただちに所定の溶接電
流Iwを流すと母材の溶融部分が吹き飛ばされるの
で、これを防止するためである。 Relay when worker closes main switch MS
SOL 1 is energized, solenoid valve 14 opens, and a small flow rate (F w ) of working gas determined by flow rate regulating valve 12 begins to flow into torch 11 (as shown in Figure 3a).
Next, when start switch ST is closed, relay
, and also close contact X 2 . When contact X 2 closes, the normally closed contact of welding current detector 18 at this stage.
Since A 1 is closed, the relay SOL 2 is connected through that contact.
is energized, the solenoid valve 15 opens, and the working gas flows at a flow rate determined by the flow rate adjustment valve 13.
In addition to the working gas flowing through the torch 11, a large amount (Fs) of working gas flows into the torch 11 (at the time of FIG. 3b).
When the working gas at the flow rate Fs flows into the torch 11, the plasma jet 7 expands and eventually comes into contact with the base metal 8, generating a plasma arc, that is, the starting current (Is) begins to flow (as shown in Figure 3c). When the start current begins to flow, the contact is activated by the welding current detector 18.
A 1 opens to deenergize relay SOL 2 , which closes solenoid valve 15 and reduces the flow of working gas into torch 11. At the same time, the normally open contact A2 of the welding current detector 18 is closed, and the timer T for the welding current rise timing is energized. The set time t of the timer T is the time it takes for the working gas flow rate to shift from the large flow rate Fs at startup to the flow rate Fw at the time of welding.After the elapse of this time t, a welding current control circuit (not shown) operates to maintain a predetermined value. Start increasing the welding current to the value Iw (point d in Figure 3). The reason why the welding current Iw is applied with a time lag in this way is because, as mentioned above, if the specified welding current Iw is applied immediately when a large amount of working gas is flowing, the molten part of the base metal will be blown away. This is to prevent
（発明の効果）
以上のとうり本発明によれば起動時における作
動ガス流量を加工時よりも大きくするという簡単
な操作で、ノズル先端に発生したプラズマジエツ
トをノズル前方に強く押し出して母材に接触さ
せ、これにより確実に電極−母材間にプラズマア
ークを起動させることができる。(Effects of the Invention) As described above, according to the present invention, the plasma jet generated at the nozzle tip is strongly pushed out in front of the nozzle by a simple operation of increasing the working gas flow rate at the time of start-up compared to that during machining. This makes it possible to reliably start a plasma arc between the electrode and the base material.
第１図は本発明に係るプラズマアーク溶接機の
具体例を示す図、第２図はその電気回路図、第３
図はタイムチヤート図、第４図はプラズマジエツ
トの形成状態を示す図である。
１……電極、９……パイロツトアーク用電源、
１０……溶接電源、１１……プラズマアークトー
チ、２２……作動ガス供給制御部。
FIG. 1 is a diagram showing a specific example of a plasma arc welding machine according to the present invention, FIG. 2 is an electric circuit diagram thereof, and FIG.
The figure is a time chart, and FIG. 4 is a diagram showing the state of plasma jet formation. 1... Electrode, 9... Pilot arc power supply,
10... Welding power source, 11... Plasma arc torch, 22... Working gas supply control section.
Claims (1)
してプラズマジエツト長を伸ばし、母材に接触さ
せ、電極−母材間にプラズマアークを発生させ、
スタート電流を加工時の電流よりも小にすること
を特徴とするプラズマアークの起動方法。1. Increase the working gas flow rate at startup to more than double that during processing to extend the plasma jet length, bring it into contact with the base material, and generate a plasma arc between the electrode and the base material.
A plasma arc starting method characterized by making the starting current smaller than the current during machining.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP17798184A JPS6182975A (en) | 1984-08-27 | 1984-08-27 | How to start the plasma arc |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP17798184A JPS6182975A (en) | 1984-08-27 | 1984-08-27 | How to start the plasma arc |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6182975A JPS6182975A (en) | 1986-04-26 |
| JPH037471B2 true JPH037471B2 (en) | 1991-02-01 |
Family
ID=16040447
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP17798184A Granted JPS6182975A (en) | 1984-08-27 | 1984-08-27 | How to start the plasma arc |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6182975A (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP6728022B2 (en) * | 2016-11-07 | 2020-07-22 | 株式会社ダイヘン | Arc start control method for plasma arc welding |
| JP6796361B2 (en) * | 2016-11-18 | 2020-12-09 | 株式会社ダイヘン | Arc start control method for plasma arc welding |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5623696B2 (en) * | 1973-02-28 | 1981-06-02 | ||
| JPS569636B2 (en) * | 1973-05-28 | 1981-03-03 | ||
| JPS5332853A (en) * | 1976-09-08 | 1978-03-28 | Kobe Steel Ltd | Arc welding |
| JPS53125250A (en) * | 1977-04-08 | 1978-11-01 | Shin Meiwa Ind Co Ltd | Arc start method in automatic welding machine |
| JPS5550975A (en) * | 1978-10-11 | 1980-04-14 | Toyota Motor Corp | Plasma arc welding starting method |
| JPS5684940A (en) * | 1979-11-15 | 1981-07-10 | Mitsuboshi Belting Ltd | Bonding technique for vulcanized synthetic rubber waterproof sheet |
-
1984
- 1984-08-27 JP JP17798184A patent/JPS6182975A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6182975A (en) | 1986-04-26 |
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