JP2006035288A

JP2006035288A - Plasma welding power source

Info

Publication number: JP2006035288A
Application number: JP2004221603A
Authority: JP
Inventors: Toshio Oonawa; 登史男大縄; Tokuji Fujii; 督ニ藤井
Original assignee: Daihen Corp
Current assignee: Daihen Corp
Priority date: 2004-07-29
Filing date: 2004-07-29
Publication date: 2006-02-09

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma welding power source which can perform a gas purge work in a short period of time and ensure the good ignitability of a pilot arc at the time of recommencing welding work. <P>SOLUTION: The plasma welding power source is equipped with a plasma gas flow regulating mechanism which regulates the flow of plasma gas to be supplied to a plasma torch to generate plasma arcs, and has a large flow passage for feeding a preset large volume of plasma gas, a medium flow passage for feeding a preset medium volume of plasma gas, and a small flow passage for feeding a preset small volume of plasma gas. A large volume of plasma gas is supplied through the large flow passage when a main switch is turned on, a medium volume of plasma gas is supplied through the medium flow passage when a pilot arc start-up switch is turned on, and a small volume of plasma gas is supplied through the small flow passage during a period after the pilot arc start-up switch is turned off until it is turned on again. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

本発明は、プラズマガスへの水分の混入を抑制して、プラズマ溶接の品質を向上させるためのプラズマトーチへのガス供給方法を改善したプラズマ溶接電源に関するものである。 The present invention relates to a plasma welding power source in which a gas supply method to a plasma torch for improving the quality of plasma welding by suppressing the mixing of moisture into the plasma gas is improved.

図６は、従来技術におけるプラズマ溶接装置の構成図である。同図において、電極１１と母材２との間に主プラズマアーク３が発生する。この主プラズマアーク３を発生させるために、プラズマノズル１２内にプラズマガス４を流す。また、プラズマアーク発生部及び母材２の溶融部を空気から遮蔽するために、シールドガスカップ１３内にシールドガス５を流す。
プラズマトーチ１は、主に上記の電極１１、プラズマノズル１２、シールドガスカップ１３からなり、タングステン電極を一般的に陰極として放電した際のプラズマを、水冷されたプラズマノズル１２とプラズマガス４のガス流によって拘束することで、集中性の良い主プラズマアーク３を発生させる。上記のプラズマガス４及びシールドガス５にはアルゴンガスが一般的に使用される。 FIG. 6 is a configuration diagram of a plasma welding apparatus in the prior art. In the figure, a main plasma arc 3 is generated between the electrode 11 and the base material 2. In order to generate the main plasma arc 3, a plasma gas 4 is caused to flow in the plasma nozzle 12. Further, in order to shield the plasma arc generation part and the melting part of the base material 2 from the air, the shield gas 5 is caused to flow in the shield gas cup 13.
The plasma torch 1 is mainly composed of the electrode 11, the plasma nozzle 12, and the shield gas cup 13, and plasma of the plasma nozzle 12 and the plasma gas 4 that are cooled by water is used when the tungsten electrode is generally discharged as a cathode. By constraining by the flow, the main plasma arc 3 with good concentration is generated. Argon gas is generally used as the plasma gas 4 and the shield gas 5.

プラズマガス４は、プラズマガスボンベ６からガスホース７によってプラズマ溶接電源８に供給される。そして、プラズマガス４は、プラズマガス流量調整器１０及びプラズマガス電磁弁１４が設けられたプラズマガス流路９を経て、プラズマ溶接電源８からガスホース７によってプラズマトーチ１に供給される。
同様に，シールドガス５は、シールドガスボンベ１５からガスホース７によって溶接電源８に供給される。そして、シールドガス５は、シールドガス流量調整器１７及びシールドガス電磁弁１８が設けられたシールドガス流路１６を経て、プラズマ溶接電源８からガスホース７によってプラズマトーチ１に供給される。
上記のプラズマガス流量調整器１０とシールドガス流量調整器１７は、プラズマガス４及びシールドガス５のそれぞれの流量を調整する。一般的に、プラズマガス４の流量は、約０．１リットル／分〜２リットル／分に調整され、シールドガス５の流量は、約１０リットル／分に調整される。上記のプラズマガス電磁弁１４及びシールドガス電磁弁１８は、プラズマガス４及びシールドガス５のそれぞれの放流の開閉を制御する。（例えば、特許文献１参照。）。 The plasma gas 4 is supplied from a plasma gas cylinder 6 to a plasma welding power source 8 by a gas hose 7. The plasma gas 4 is supplied from the plasma welding power source 8 to the plasma torch 1 by the gas hose 7 through the plasma gas flow path 9 provided with the plasma gas flow rate regulator 10 and the plasma gas solenoid valve 14.
Similarly, the shield gas 5 is supplied from the shield gas cylinder 15 to the welding power source 8 by the gas hose 7. The shield gas 5 is supplied from the plasma welding power source 8 to the plasma torch 1 by the gas hose 7 through the shield gas flow path 16 provided with the shield gas flow rate regulator 17 and the shield gas electromagnetic valve 18.
The plasma gas flow controller 10 and the shield gas flow controller 17 adjust the flow rates of the plasma gas 4 and the shield gas 5, respectively. Generally, the flow rate of the plasma gas 4 is adjusted to about 0.1 liter / minute to 2 liters / minute, and the flow rate of the shield gas 5 is adjusted to about 10 liter / minute. The plasma gas solenoid valve 14 and the shield gas solenoid valve 18 control the opening and closing of the respective discharges of the plasma gas 4 and the shield gas 5. (For example, refer to Patent Document 1).

以下、動作を説明する。
図６において、プラズマ溶接電源８にパイロットアーク起動信号が入力されると、先ず、プラズマガス電磁弁１４が開きプラズマガス４のプリフローが開始される。そして、数秒後に電極１１とプラズマノズル１２との間に高周波が印加されて、電極１１とプラズマノズル１２との間にパイロットアークが点弧する。
その後、トーチスイッチ起動信号が入力されると、シールドガス電磁弁１８が開き、シールドガス５がプラズマトーチ１に供給されて、電極１１と母材２との間に主プラズマアーク３が発生する。そして、プラズマ溶接が開始される。 The operation will be described below.
In FIG. 6, when a pilot arc activation signal is input to the plasma welding power source 8, first, the plasma gas solenoid valve 14 is opened and the preflow of the plasma gas 4 is started. A few seconds later, a high frequency is applied between the electrode 11 and the plasma nozzle 12, and a pilot arc is ignited between the electrode 11 and the plasma nozzle 12.
Thereafter, when a torch switch activation signal is input, the shield gas electromagnetic valve 18 is opened, the shield gas 5 is supplied to the plasma torch 1, and the main plasma arc 3 is generated between the electrode 11 and the base material 2. Then, plasma welding is started.

プラズマ溶接の現場において、プラズマガス４及びシールドガス５に使用されるアルゴンガスは、ガスホース７及び各流路を経由してプラズマトーチ１に供給されるため、これらの経路内で純度が低下することがある。特にゴムホースを経由する場合、水分の透過係数は、理想的な溶接用ホース材料と言われる軟質フッ素樹脂の約１０の６乗倍であるので、ガスホース７内に水分が透過して、プラズマガス４及びシールドガス５中の水分量を上昇させる。 At the plasma welding site, the argon gas used for the plasma gas 4 and the shield gas 5 is supplied to the plasma torch 1 via the gas hose 7 and each flow path, so that the purity is reduced in these paths. There is. In particular, when passing through a rubber hose, the moisture permeability coefficient is about 10 6 times that of a soft fluororesin, which is said to be an ideal welding hose material. And the amount of moisture in the shielding gas 5 is increased.

プラズマガス４内の水分が上昇すると、アルミの溶接の場合、ブローホールを発生させる原因となり、ステンレスの溶接の場合、溶接焼けの原因となる。
また、タングステン電極の先端が酸化して、パイロットアークの点弧性が著しく損なわれ、電極１１の寿命が著しく短くなるという問題が発生する。 When the moisture in the plasma gas 4 rises, it causes a blowhole in the case of aluminum welding, and causes a burn in the case of stainless steel welding.
Further, the tip of the tungsten electrode is oxidized, and the ignition performance of the pilot arc is remarkably impaired, and the life of the electrode 11 is remarkably shortened.

そこで、ガスホース７内に浸透した水分を除去するために、溶接を行わずにガスホース７内にアルゴンガスを長時間放流する作業（以下、ガスパージ作業という）を行う必要がある。
図７は長さ１０メートルの一般的なガスホースを用いて、１０リットル／分のアルゴンガスを流してガスパージ作業を行ったときのガスパージ時間（横軸）と露点の変化（縦軸）を示す図である。同図において、露点が−６０℃を下回るためには、１０リットル／分のアルゴンガスを３分以上流す必要がある。単純に積算流量で計算すると、３０リットル以上のアルゴンガスを流さなくてはならない。 Therefore, in order to remove moisture that has permeated into the gas hose 7, it is necessary to perform an operation for discharging the argon gas into the gas hose 7 for a long time without performing welding (hereinafter referred to as a gas purge operation).
FIG. 7 is a graph showing a gas purge time (horizontal axis) and a dew point change (vertical axis) when a gas purge operation is performed by flowing an argon gas of 10 liters / minute using a general gas hose having a length of 10 meters. It is. In the figure, in order for the dew point to fall below -60 ° C., it is necessary to flow argon gas of 10 liters / minute for 3 minutes or more. If simply calculated by the integrated flow rate, an argon gas of 30 liters or more must flow.

シールドガス用のガス流量調整器は、通常、一般的な溶接用のガス流量調整器である最大２５リットル／分のガス流量調整器が用いられる。一方、プラズマガス用のガス流量調整器の分解能としては、最低０．０５リットル／分以下が必要であり、また、最大２リットル／分程度の流量で十分であるので、プラズマガス用のガス流量調整器には、最大２リットル／分のガス流量調整器を用いる。この場合、例えばフロート式のガス流量調整器を用いた場合、２リットル／分のガス流量調整器の最大流量は、ニードル弁を最大に開いた状態でも５リットル／分しか流すことができない。
このように、プラズマガス用のガス流量調整器は、一般的に、容量が小さいために、ニードル弁を最大に開いた状態でも、５リットル／分程度の流量しか得ることができない。従って、単純計算で３０リットルのアルゴンガスを流すためには６分間必要になり、プラズマ溶接電源を起動させてから行うガスパージ作業にかなりの時間が掛かることになる。 As the gas flow rate regulator for shield gas, a gas flow rate regulator of a maximum of 25 liters / minute, which is a general welding gas flow rate regulator, is usually used. On the other hand, the resolution of the gas flow rate regulator for plasma gas requires a minimum of 0.05 liter / min or less, and a maximum flow rate of about 2 liter / min is sufficient, so the gas flow rate for plasma gas is sufficient. The regulator uses a gas flow regulator up to 2 liters / minute. In this case, for example, when a float type gas flow regulator is used, the maximum flow rate of the gas flow regulator of 2 liters / minute can flow only 5 liters / minute even when the needle valve is fully opened.
As described above, the gas flow rate regulator for plasma gas generally has a small capacity, so that only a flow rate of about 5 liters / minute can be obtained even when the needle valve is fully opened. Therefore, it takes 6 minutes to flow 30 liters of argon gas by simple calculation, and it takes a considerable amount of time to perform the gas purging operation after starting the plasma welding power source.

通常、プラズマ溶接の現場においては、プラズマガス４の流量をプラズマガス流量調整器１０のニードル弁で頻繁に調整することはなく、プラズマ溶接中に使用する流量に固定されている。プラズマ溶接中に使用するプラズマガス４の最小流量は０．２リットル／分である場合もあり、その場合、３０リットルのアルゴンを流すためには２時間以上のガスパージ作業が必要であり、作業効率を著しく低下させる。 Usually, in the plasma welding field, the flow rate of the plasma gas 4 is not frequently adjusted by the needle valve of the plasma gas flow rate regulator 10, but is fixed to the flow rate used during plasma welding. In some cases, the minimum flow rate of the plasma gas 4 used during plasma welding is 0.2 liter / min. In this case, in order to flow 30 liters of argon, a gas purge operation of 2 hours or more is required, and the work efficiency is increased. Is significantly reduced.

また、プラズマ溶接作業を休憩又は昼食等で中断するときに、パイロットアークを消弧し、プラズマガス４を止める。そして、プラズマ溶接作業を再開するまでの僅かな休止時間中に、ガスホース７に水分が浸入する。その結果、パイロットアークを再点弧する際に、タングステン電極１１の先端が酸化し、パイロットアークの点弧に失敗が生じる。この場合、作業者は電極を削り直し、ガスホース７のガスパージ作業を再度行う必要があり、さらに、作業効率を著しく低下させる。
特開昭６４−８３３７６号公報 Further, when the plasma welding operation is interrupted by a break or lunch, the pilot arc is extinguished and the plasma gas 4 is stopped. Then, moisture enters the gas hose 7 during a brief pause until the plasma welding operation is resumed. As a result, when the pilot arc is re-ignited, the tip of the tungsten electrode 11 is oxidized, and the pilot arc is unsuccessfully fired. In this case, it is necessary for the operator to re-shave the electrode and perform the gas purging operation of the gas hose 7 again, and the working efficiency is significantly reduced.
JP-A-64-83376

上述したように、プラズマガス流量調整器１０は、一般的に、容量が小さいために、プラズマ溶接電源８を起動させてから行うガスパージ作業にかなりの時間が掛かる。
また、溶接作業を休憩又は昼食等で中断するときに、パイロットアークを消弧し、プラズマガス４を止める。その結果、パイロットアークを再点弧する際に、タングステン電極の先端が酸化し、パイロットアークの点弧に失敗が生じるので、作業者は電極を削り直し、ガスパージ作業を再度行う必要があり、作業効率を著しく低下させる。 As described above, since the plasma gas flow rate regulator 10 generally has a small capacity, it takes a considerable amount of time to perform a gas purge operation after the plasma welding power source 8 is activated.
Further, when the welding operation is interrupted by a break or lunch, the pilot arc is extinguished and the plasma gas 4 is stopped. As a result, when the pilot arc is re-ignited, the tip of the tungsten electrode is oxidized and the pilot arc fails to fire, so the operator must re-cut the electrode and perform the gas purge operation again. Reduces efficiency significantly.

本発明は、短時間でガスパージ作業を行うことができ、作業再開時にパイロットアークの良好な点弧性を確保できるプラズマ溶接電源を提供することを目的としている。 An object of the present invention is to provide a plasma welding power source that can perform a gas purge operation in a short time and can ensure good ignition performance of a pilot arc when the operation is resumed.

上記目的を達成するために、第１の発明は、
プラズマアークを発生させるためにプラズマトーチに供給するプラズマガスの流量を調整する一つの流路を設けたプラズマガス流量調整機構を備えたプラズマ溶接電源において、
前記一つの流路を設けたプラズマガス流量調整機構の代わりに予め設定された大流量のプラズマガスを流す大流量用流路と予め設定された中流量のプラズマガスを流す中流量用流路とを設けたプラズマガス流量調整機構を備え、
メインスイッチがＯＮに成ると大流量用流路を通って前記大流量のプラズマガスを供給し、
パイロットアーク起動スイッチがＯＮに成ると中流量用流路を通って前記中流量のプラズマガスを供給し、
以後、パイロットアーク起動スイッチのＯＦＦ又はＯＮにかかわらず前記メインスイッチがＯＦＦに成るまで前記中流量のプラズマガスを供給し続けることを特徴とするプラズマ溶接電源である。 In order to achieve the above object, the first invention provides:
In a plasma welding power source equipped with a plasma gas flow rate adjusting mechanism provided with a single flow path for adjusting the flow rate of plasma gas supplied to the plasma torch to generate a plasma arc,
Instead of the plasma gas flow rate adjusting mechanism provided with the one flow channel, a large flow rate channel for flowing a preset large flow rate plasma gas, and a medium flow rate channel for flowing a preset medium flow rate plasma gas, Equipped with a plasma gas flow rate adjusting mechanism,
When the main switch is turned ON, the large flow rate plasma gas is supplied through the large flow rate channel,
When the pilot arc start switch is turned on, the medium flow plasma gas is supplied through the medium flow passage,
Thereafter, the plasma welding power source is characterized in that the medium-flow plasma gas is continuously supplied until the main switch is turned off regardless of whether the pilot arc starting switch is turned off or on.

第２の発明は、
前記プラズマガス流量調整機構に予め設定された小流量のプラズマガスを流す小流量用流路を追加し、前記パイロットアーク起動スイッチがＯＦＦに成ってから再度ＯＮに成るまで前記小流量用流路を通って前記小流量のプラズマガスを供給することを特徴とする第１の発明に記載のプラズマ溶接電源である。 The second invention is
A small flow passage for flowing a preset small flow plasma gas is added to the plasma gas flow adjustment mechanism, and the small flow passage is provided until the pilot arc start switch is turned off and then on again. The plasma welding power source according to the first aspect of the present invention is characterized in that the small-flow plasma gas is supplied through the plasma welding power source.

第３の発明は、
前記プラズマガス流量調整機構に第１の電磁弁と前記中流量のプラズマガスを流すように予め調整したプラズマガス流量調整器とを直列に設け前記大流量のプラズマガスを流すことができる内径を有した第１の流路と第２の電磁弁を設けて前記大流量のプラズマガスを流すことができる内径を有し前記プラズマガス流量調整器と並列に連結した第２の流路とを備え、
前記メインスイッチがＯＮに成ると前記第１の電磁弁及び前記第２の電磁弁を開いて前記第１の流路及び前記第２の流路から成る前記大流量用流路を通って前記大流量のプラズマガスを供給し、
前記パイロットアーク起動スイッチがＯＮになると前記第２の電磁弁を閉じて前記第１の流路から成る前記中流量用流路を通って前記中流量のプラズマガスを供給し、
以後、パイロットアーク起動スイッチのＯＦＦ又はＯＮにかかわらず前記メインスイッチがＯＦＦに成るまで前記中流量のプラズマガスを供給し続けることを特徴とする第１の発明に記載のプラズマ溶接電源である。 The third invention is
The plasma gas flow rate adjusting mechanism is provided with a first solenoid valve and a plasma gas flow rate regulator that has been adjusted in advance so as to flow the medium flow rate plasma gas in series, and has an inner diameter capable of flowing the large flow rate plasma gas. A first flow path and a second flow path connected to the plasma gas flow controller in parallel with an inner diameter capable of flowing the large flow rate plasma gas by providing a second solenoid valve;
When the main switch is turned on, the first solenoid valve and the second solenoid valve are opened, and the large flow rate channel including the first channel and the second channel is passed through the large flow rate channel. Supplying a flow of plasma gas,
When the pilot arc start switch is turned on, the second electromagnetic valve is closed and the medium flow rate plasma gas is supplied through the medium flow rate flow path including the first flow path.
Thereafter, the plasma welding power source according to the first invention is characterized in that the medium-flow plasma gas is continuously supplied until the main switch is turned off regardless of whether the pilot arc starting switch is turned off or on.

第４の発明は、
前記プラズマガス流量調整機構に第３の電磁弁を設けて小流量のプラズマガスを流すことができる内径を有し前記第１の流路の前記プラズマガス流量調整器及び前記第１の電磁弁と並列に連結した第３の流路を追加して、
前記パイロットアーク起動スイッチがＯＦＦに成ってから再度ＯＮに成るまで前記第１の電磁弁を閉じて前記第３の電磁弁を開いて前記第３の流路を通って前記小流量のプラズマガスを供給することを特徴とする第３の発明に記載のプラズマ溶接電源である。 The fourth invention is:
The plasma gas flow rate adjusting mechanism is provided with a third solenoid valve, and has an inner diameter that allows a small flow rate of plasma gas to flow, and the plasma gas flow rate regulator and the first solenoid valve in the first flow path, Add a third channel connected in parallel,
The first solenoid valve is closed and the third solenoid valve is opened until the pilot arc start switch is turned on again and then the third solenoid valve is opened, and the small flow rate plasma gas is passed through the third flow path. A plasma welding power source according to a third aspect of the invention, characterized in that the plasma welding power source is supplied.

第５の発明は、
前記プラズマガス流量調整機構に第１の電磁弁と流量設定信号によってプラズマガスの流量を調整する電子式流量調整器とを直列に設け前記大流量のプラズマガスを流すことができる内径を有した第４の流路と第２の電磁弁を設けて前記大流量のプラズマガスを流すことができる内径を有して前記電子式流量調整器と並列に連結した第２の流路とを備え、
前記メインスイッチがＯＮに成ると前記第１の電磁弁及び前記第２の電磁弁を開いて前記流量設定信号を前記中流量のプラズマガスを流す信号にして前記第４の流路及び前記第２の流路から成る前記大流量用流路を通って前記大流量のプラズマガスを供給し、
前記パイロットアーク起動スイッチがＯＮになると前記第２の電磁弁を閉じて前記第４の流路から成る前記中流量用流路を通って前記中流量のプラズマガスを供給し、
以後、パイロットアーク起動スイッチのＯＦＦ又はＯＮにかかわらず前記メインスイッチがＯＦＦに成るまで前記中流量のプラズマガスを供給し続けることを特徴とする第１の発明に記載のプラズマ溶接電源である。 The fifth invention is:
The plasma gas flow rate adjusting mechanism is provided with a first solenoid valve and an electronic flow rate regulator for adjusting the flow rate of the plasma gas by a flow rate setting signal in series, and has an inner diameter capable of flowing the high flow rate plasma gas. 4 and a second electromagnetic valve provided with a second electromagnetic valve and having an inner diameter capable of flowing the large flow rate plasma gas and connected in parallel with the electronic flow regulator,
When the main switch is turned ON, the first solenoid valve and the second solenoid valve are opened, and the flow rate setting signal is made a signal for flowing the medium flow rate plasma gas, and the fourth flow path and the second Supplying the large flow rate plasma gas through the large flow rate flow path comprising
When the pilot arc start switch is turned ON, the second electromagnetic valve is closed and the medium flow rate plasma gas is supplied through the medium flow rate flow path including the fourth flow path.
Thereafter, the plasma welding power source according to the first invention is characterized in that the medium-flow plasma gas is continuously supplied until the main switch is turned off regardless of whether the pilot arc starting switch is turned off or on.

第６の発明は、
前記パイロットアーク起動スイッチがＯＦＦに成ってから再度ＯＮに成るまで前記流量設定信号を小流量の前記プラズマガスを流す信号に切換えて前記第４の流路を通って前記小流量のプラズマガスを供給することを特徴とする第５の発明に記載のプラズマ溶接電源である。 The sixth invention is:
The flow rate setting signal is switched to a signal for flowing the plasma gas at a small flow rate until the pilot arc start switch is turned on again after the pilot arc start switch is turned on, and the plasma gas at the small flow rate is supplied through the fourth flow path. A plasma welding power source according to the fifth aspect of the invention.

第１の発明及び第３の発明及び第５の発明は、ガスパージ期間に大流量のプラズマガスを供給することができるので、短時間でガスパージ作業を行うことができ、作業の効率化を図ることができる。 In the first invention, the third invention, and the fifth invention, since a large flow rate of plasma gas can be supplied during the gas purge period, the gas purge work can be performed in a short time, and the work efficiency can be improved. Can do.

第２の発明及び第４の発明及び第６の発明は、溶接作業を断続的に行う場合において、パイロットアーク消弧後も少量のプラズマガスを流し続け、プラズマガスの露点上昇を防ぐことができる。その結果、作業再開時にパイロットアークの良好な点弧性を確保でき、再ガスパージ又は電極の研ぎなおしの作業を行う必要が無く、電極の寿命が延び、作業の効率化を図ることができる。 In the second invention, the fourth invention, and the sixth invention, when a welding operation is performed intermittently, a small amount of plasma gas can continue to flow even after the pilot arc is extinguished, thereby preventing an increase in the dew point of the plasma gas. . As a result, it is possible to ensure a good ignition performance of the pilot arc when resuming the work, there is no need to perform a re-gas purge or an electrode sharpening work, the life of the electrode is extended, and the work efficiency can be improved.

第５の発明及び第６の発明は、上記の効果に加えて、電子式流量調整器に入力される流量設定信号を変更することによって、プラズマガスの流量を容易に調整することができ、より適切なプラズマ溶接を行うことができる。 In addition to the above effects, the fifth and sixth inventions can easily adjust the flow rate of the plasma gas by changing the flow rate setting signal input to the electronic flow rate regulator. Appropriate plasma welding can be performed.

本発明の実施の形態を図面を参照して説明する。
［実施の形態１］
図１は、本発明の実施の形態１のプラズマ溶接装置の構成図である。同図において、プラズマ溶接電源２６内に設けられた第１の流路１９は、大流量のプラズマガスを流すことができる内径を有し、第１の電磁弁２１とプラズマ溶接に適した中流量のプラズマガスを流すように予め調整されたプラズマガス流量調整器２０とを直列に設けられている。また、第２の流路２２は、大流量のプラズマガスを流すことができる内径を有し、第２の電磁弁２３が設けられて、第１の流路に設けたプラズマガス流量調整器２０と並列に連結している。
さらに,小流量のプラズマガスを流すことができる内径を有する第３の流路２４に第３の電磁弁２５を設け、第１の流路のプラズマガス流量調整器２０及び第１の電磁弁２１と並列に連結している。その他の図６に示した機能と同機能に同符号を付して、説明を省略する。
これらの第１の流路１９、第２の流路２２及び第３の流路２４によりプラズマガス流量調整機構が構成されている。 Embodiments of the present invention will be described with reference to the drawings.
[Embodiment 1]
FIG. 1 is a configuration diagram of a plasma welding apparatus according to Embodiment 1 of the present invention. In the figure, a first flow path 19 provided in the plasma welding power source 26 has an inner diameter capable of flowing a large flow rate of plasma gas, and a medium flow rate suitable for the first electromagnetic valve 21 and plasma welding. A plasma gas flow rate regulator 20 that is adjusted in advance so as to flow the plasma gas is provided in series. The second flow path 22 has an inner diameter through which a large flow rate of plasma gas can flow, and is provided with a second electromagnetic valve 23 to provide a plasma gas flow rate regulator 20 provided in the first flow path. And connected in parallel.
Further, a third electromagnetic valve 25 is provided in the third flow path 24 having an inner diameter through which a small flow rate of plasma gas can flow, and the plasma gas flow rate regulator 20 and the first electromagnetic valve 21 in the first flow path are provided. And connected in parallel. The same functions as those shown in FIG. 6 are denoted by the same reference numerals, and description thereof is omitted.
The first flow path 19, the second flow path 22 and the third flow path 24 constitute a plasma gas flow rate adjusting mechanism.

以下、図２に示すタイムチャートを参照して、動作を説明する。図２は、本発明の実施の形態１のプラズマ溶接装置のタイムチャートである。同図（Ａ）はメインスイッチ、同図（Ｂ）はガスパージ／プロセス切替えスイッチ、同図（Ｃ）はパイロットアーク起動スイッチ、同図（Ｄ）はトーチスイッチ、同図（Ｅ）はパイロットアーク電流、同図（Ｆ）は主プラズマアーク電流、同図（Ｇ）は第１の電磁弁、同図（Ｈ）は第２の電磁弁、同図（Ｉ）は第３の電磁弁、同図（Ｊ）はシールドガス電磁弁のそれぞれの時間経過を示す。溶接条件として、プラズマガスの流量を０．５リットル／分、シールドガスの流量を１０リットル／分とする。 The operation will be described below with reference to the time chart shown in FIG. FIG. 2 is a time chart of the plasma welding apparatus according to the first embodiment of the present invention. (A) is the main switch, (B) is the gas purge / process switch, (C) is the pilot arc start switch, (D) is the torch switch, and (E) is the pilot arc current. (F) is the main plasma arc current, (G) is the first solenoid valve, (H) is the second solenoid valve, (I) is the third solenoid valve, and FIG. (J) shows each time passage of the shield gas solenoid valve. As welding conditions, the flow rate of plasma gas is 0.5 liter / minute, and the flow rate of shield gas is 10 liter / minute.

図２（Ａ）に示す時刻ｔ１において、プラズマ溶接電源２６のメインスイッチがＯＮになると、同図（Ｇ）に示すように、第１の電磁弁２１が開き、同図（Ｂ）に示すように、内部スイッチのガスパージ／プロセス切替えスイッチがパージ側になるので、同図（Ｈ）に示すように、第２の電磁弁２３が開く。第１の流路１９及び第２の流路２２の内径は、大流量のプラズマガスを流すことができる内径であり、第１の流路及び第２の流路から成る大流量用流路を通って大流量のプラズマガス４が流れる。この大流量のプラズマガス４によってガスパージが行われる。 When the main switch of the plasma welding power source 26 is turned on at time t1 shown in FIG. 2 (A), the first electromagnetic valve 21 is opened as shown in FIG. 2 (G), as shown in FIG. 2 (B). In addition, since the gas purge / process switch of the internal switch is on the purge side, the second electromagnetic valve 23 is opened as shown in FIG. The inner diameters of the first flow path 19 and the second flow path 22 are the inner diameters through which a large flow rate of plasma gas can flow, and the large flow rate flow path composed of the first flow path and the second flow path. A large flow rate of plasma gas 4 flows therethrough. A gas purge is performed by the plasma gas 4 having a large flow rate.

時刻ｔ２において、同図（Ｃ）に示すように、パイロットアーク起動スイッチがＯＮになると、同図（Ｂ）に示すように、ガスパージ／プロセス切替えスイッチがプロセス側に切り替わることにより、同図（Ｈ）に示すように、第２の電磁弁２３を閉じ、第１の流路１９から成る中流量用流路を通ってプラズマ溶接に適した中流量のプラズマガス４の流量が流れるようになる。そして、電極１１とプラズマノズル１２との間に高周波電圧を印加して、パイロットアークを始動させる。 At time t2, when the pilot arc start switch is turned on as shown in FIG. 10C, the gas purge / process changeover switch is switched to the process side as shown in FIG. ), The second electromagnetic valve 23 is closed, and the flow rate of the plasma gas 4 having a medium flow rate suitable for plasma welding flows through the medium flow rate flow channel formed by the first flow channel 19. Then, a high frequency voltage is applied between the electrode 11 and the plasma nozzle 12 to start a pilot arc.

時刻ｔ３において、同図（Ｄ）に示すように、トーチスイッチがＯＮに成ると、同図（Ｆ）に示すように、主プラズマアーク電流が流れ、同図（Ｊ）に示すように、シールドガス電磁弁１８が開いて、シールドガス５が流れ、溶接を開始する。 At time t3, when the torch switch is turned on as shown in FIG. 4D, the main plasma arc current flows as shown in FIG. 4F, and as shown in FIG. The gas solenoid valve 18 is opened, the shielding gas 5 flows, and welding is started.

時刻ｔ４において、同図（Ｄ）に示すように、トーチスイッチがＯＦＦになると、同図（Ｊ）に示すように、シールドガス電磁弁１８が閉じ、同図（Ｆ）に示すように、主プラズマアーク電流が停止する。このときは、パイロットアークが点弧したままである。
時刻ｔ５において、同図（Ｄ）に示すように、トーチスイッチがＯＮに成って、再び溶接を開始し、時刻ｔ６において、同図（Ｄ）に示すように、トーチスイッチがＯＦＦに成って、溶接を終了する。この時刻ｔ５からｔ６までの期間は、時刻ｔ３からｔ４までの期間の動作と同じ動作を行う。 At time t4, when the torch switch is turned off as shown in FIG. 4D, the shield gas solenoid valve 18 is closed as shown in FIG. 4J, and as shown in FIG. Plasma arc current stops. At this time, the pilot arc remains ignited.
At time t5, as shown in FIG. 4D, the torch switch is turned on and welding is started again. At time t6, the torch switch is turned off as shown in FIG. Finish welding. In the period from time t5 to t6, the same operation as that in the period from time t3 to t4 is performed.

時刻ｔ７において、作業者は休憩又は昼食等で溶接作業を中断して、現場を離れるので、同図（Ｃ）に示すように、パイロットアーク起動スイッチをＯＦＦにする。しかし、同図（Ａ）に示すように、メインスイッチがＯＮ状態で、同図（Ｂ）に示すように、ガスパージ／プロセス切替えスイッチがプロセス側なので、待機期間に入る。
この待機期間では、同図（Ｇ）に示すように、第１の電磁弁２１を閉じ、同図（Ｉ）に示すように、第３の電磁弁２５を開く。第３の流路２４の内径は、小流量のプラズマガスを流すことができる内径であり、第３の流路２４を通って小流量のプラズマガス４を流す。この小流量のプラズマガス４によってガスホース７内に浸透してくる水分をガスパージによって放出させることができる。 At time t7, the operator interrupts the welding operation at break or lunch and leaves the site, so the pilot arc starting switch is turned OFF as shown in FIG. However, as shown in FIG. 6A, the main switch is in the ON state, and as shown in FIG. 4B, the gas purge / process changeover switch is on the process side, so the standby period starts.
In this standby period, the first electromagnetic valve 21 is closed as shown in FIG. 5G, and the third electromagnetic valve 25 is opened as shown in FIG. The inner diameter of the third flow path 24 is an inner diameter through which a small flow rate of plasma gas can flow, and the small flow rate of the plasma gas 4 flows through the third flow path 24. Moisture permeating into the gas hose 7 by this small flow rate of the plasma gas 4 can be released by gas purge.

時刻ｔ８において、作業者が現場に戻り、同図（Ｃ）に示すように、パイロットアーク起動スイッチをＯＮにすると、同図（Ｉ）に示すように、第３の電磁弁２５が閉じて、同図（Ｇ）に示すように、第１の電磁弁２１が開いて、時刻ｔ９からｔ１０において、時刻ｔ３からｔ４までの動作と同じ動作を行って、溶接作業を終了する。 At time t8, when the operator returns to the work site and turns on the pilot arc start switch as shown in FIG. 10C, the third electromagnetic valve 25 is closed as shown in FIG. As shown in FIG. 5G, the first solenoid valve 21 is opened, and from time t9 to t10, the same operation as that from time t3 to t4 is performed, and the welding operation is completed.

時刻ｔ１１において、同図（Ｃ）に示すように、パイロットアーク起動スイッチをＯＦＦにすると、時刻ｔ７のときと同じように、待機期間に入って小流量のプラズマガス４を流す。
時刻ｔ１２において、同図（Ａ）に示すように、メインスイッチをＯＦＦにすると、同図（Ｉ）に示すように、第３の電磁弁２５が閉じ、小流量のプラズマガス４の流れを停止する。 At time t11, as shown in FIG. 5C, when the pilot arc start switch is turned OFF, the plasma gas 4 having a small flow rate is flowed into the standby period as in the case of time t7.
At time t12, when the main switch is turned off as shown in FIG. 11A, the third electromagnetic valve 25 is closed and the flow of the plasma gas 4 having a small flow rate is stopped as shown in FIG. To do.

上述した実施の形態１においては、第３の流路２４を設けて、待機期間中に小流量のプラズマガス４を流してガスホース７内に浸透してくる水分をガスパージによって放出している。この第３の流路２４を設ける代わりに、時刻ｔ１において、メインスイッチがＯＮに成ると、第１の電磁弁２１を開き、時刻ｔ７において、パイロットアーク起動スイッチがＯＦＦに成っても第１の電磁弁２１を開き続けて中流量のプラズマガスを供給し続ける。そして、時刻ｔ１２において、メインスイッチがＯＦＦに成ると、第１の電磁弁２１を閉じて、中流量のプラズマガス４の流れを停止するようにしても良い。
この結果、プラズマ溶接中及び待機期間において、プラズマ溶接に適したプラズマガス４の流量が流れ続ける。従って、待機期間において、ガスホース７内に浸透してくる水分をガスパージによって放出させることができる。 In the first embodiment described above, the third flow path 24 is provided, and a small amount of plasma gas 4 is allowed to flow during the standby period to release moisture penetrating into the gas hose 7 by gas purge. Instead of providing the third flow path 24, when the main switch is turned on at time t1, the first electromagnetic valve 21 is opened, and even if the pilot arc starting switch is turned off at time t7, the first electromagnetic valve 21 is opened. The electromagnetic valve 21 is kept open and the medium flow plasma gas is continuously supplied. Then, when the main switch is turned off at time t12, the first electromagnetic valve 21 may be closed to stop the flow of the medium-flow plasma gas 4.
As a result, the flow rate of the plasma gas 4 suitable for plasma welding continues to flow during plasma welding and during the standby period. Therefore, in the standby period, moisture penetrating into the gas hose 7 can be released by gas purge.

図３は、５ｍのガスホースにプラズマガスを流したときの流量と露点が−６０℃を下回るまでの時間との関係を示す図である。従来技術のプラズマ溶接装置においては、プラズマ溶接に適した流量を流す流路のみによってガスパージを行うために、一般的に最大５リットル／分程度しか流すことができないので、同図に示すように、３分近いガスパージ時間が必要となる。
しかし、本発明のプラズマ溶接装置においては、ガスパージを行うときに、プラズマガス流量調整器２０と並列に連結した第２流路２２にプラズマガス４を流す。この結果、例えば、１０リットル／分以上のガス流量を確保することができれば、１分３０秒のガスパージ時間で十分であり、２０リットル／分以上のガス流量を確保することができれば、１分以内のガスパージ時間で露点が−６０℃を下回る。
そして、溶接作業時には、溶接結果にプラズマガス４の流量が著しい影響を与えるため、第２の電磁弁２３を閉じて、プラズマガス流量調整器２０を通る第１の流路１９に切替え、プラズマガス４の流量を管理することができる。
また、溶接作業を断続的に行う場合において、プラズマガス４の露点が上昇することを防ぐために、パイロットアーク消弧後も少量のプラズマガス４を流し続けることができる。その結果、溶接作業再開時にパイロットアークの良好な点弧性を確保でき、再ガスパージ又は電極の研ぎなおしの作業を行う必要が無く、電極の寿命が延び、作業の効率化を図ることができる。 FIG. 3 is a diagram showing the relationship between the flow rate when plasma gas is passed through a 5 m gas hose and the time until the dew point falls below −60 ° C. FIG. In the plasma welding apparatus of the prior art, since the gas purge is performed only by the flow path that allows a flow rate suitable for plasma welding, generally only a maximum of 5 liters / minute can be flowed. A gas purge time of nearly 3 minutes is required.
However, in the plasma welding apparatus of the present invention, when performing the gas purge, the plasma gas 4 is caused to flow through the second flow path 22 connected in parallel with the plasma gas flow rate regulator 20. As a result, for example, if a gas flow rate of 10 liters / minute or more can be secured, a gas purge time of 1 minute 30 seconds is sufficient, and if a gas flow rate of 20 liters / minute or more can be secured, within 1 minute. The dew point is below -60 ° C with the gas purge time.
During the welding operation, the flow rate of the plasma gas 4 significantly affects the welding result. Therefore, the second electromagnetic valve 23 is closed and switched to the first flow path 19 that passes through the plasma gas flow rate regulator 20. 4 flow rates can be managed.
Further, in the case where the welding operation is performed intermittently, in order to prevent the dew point of the plasma gas 4 from increasing, a small amount of the plasma gas 4 can be kept flowing even after the pilot arc is extinguished. As a result, it is possible to ensure good ignition performance of the pilot arc when resuming the welding operation, there is no need to perform a regas purge or electrode reshaping work, the life of the electrode is extended, and work efficiency can be improved.

［実施の形態２］
図４は、本発明の実施の形態２のプラズマ溶接装置の構成図である。同図において、プラズマ溶接電源２９内に設けられた第４の流路２７は、大流量のプラズマガスを流すことができる内径を有し、第１の電磁弁２１と流量設定信号によってプラズマガス４の流量を調整する電子式流量調整器２８とが直列に設けられている。また、第２の流路２２は、大流量のプラズマガスを流すことができる内径を有し、第２の電磁弁２３が設けられ、電子式流量調整器２８と並列に連結している。この電子式流量調整器２８は、入力されるアナログ電圧に比例した流量を流す。その他の図１に示した機能と同機能に同符号を付して、説明を省略する。
これらの第２の流路２２及び第４の流路２７によりプラズマガス流量調整機構が構成されている。 [Embodiment 2]
FIG. 4 is a configuration diagram of the plasma welding apparatus according to the second embodiment of the present invention. In the figure, a fourth flow path 27 provided in the plasma welding power source 29 has an inner diameter through which a large flow rate of plasma gas can flow, and the plasma gas 4 is generated by the first electromagnetic valve 21 and a flow rate setting signal. An electronic flow controller 28 for adjusting the flow rate of the gas is provided in series. The second flow path 22 has an inner diameter through which a large flow rate of plasma gas can flow, is provided with a second electromagnetic valve 23, and is connected in parallel with the electronic flow rate regulator 28. This electronic flow regulator 28 flows a flow proportional to the input analog voltage. The same functions as those shown in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted.
The second flow path 22 and the fourth flow path 27 constitute a plasma gas flow rate adjusting mechanism.

以下、図５に示すタイムチャートを参照して、動作を説明する。図５は、本発明の実施の形態２のプラズマ溶接装置のタイムチャートである。同図（Ａ）乃至（Ｈ）及び（Ｊ）は、図２に示したタイムチャートと同一機能であるので、説明を省略する。図５（Ｉ）は、電子式流量調整器２８に入力される流量設定信号の時間経過を示している。 The operation will be described below with reference to the time chart shown in FIG. FIG. 5 is a time chart of the plasma welding apparatus according to the second embodiment of the present invention. FIGS. 9A to 9H have the same function as the time chart shown in FIG. FIG. 5 (I) shows the passage of time of the flow rate setting signal input to the electronic flow rate regulator 28.

時刻ｔ１において、同図（Ａ）に示すように、プラズマ溶接電源２９のメインスイッチがＯＮになると、同図（Ｉ）に示すように、電子式流量調整器２８に入力される流量設定信号をプラズマ溶接に適した中流量のプラズマガス４が流れる信号にして、同図（Ｇ）に示すように、第１の電磁弁２１を開き、同図（Ｂ）に示すように、内部スイッチのガスパージ／プロセス切替えスイッチがパージ側になるので、同図（Ｈ）に示すように、第２の電磁弁２３が開く。
第４の流路２７及び第２の流路２２の内径は、大流量のプラズマガスを流すことができる内径であり、第４の流路及び第２の流路から成る大流量用流路を通って大流量のプラズマガス４が流れる。この大流量のプラズマガス４によってガスパージが行われる。 At time t1, when the main switch of the plasma welding power source 29 is turned on as shown in FIG. 9A, the flow rate setting signal input to the electronic flow regulator 28 is sent as shown in FIG. The first electromagnetic valve 21 is opened as shown in FIG. 5G, and a gas purge of the internal switch is performed as shown in FIG. Since the / process switch is on the purge side, the second solenoid valve 23 is opened as shown in FIG.
The inner diameters of the fourth flow path 27 and the second flow path 22 are the inner diameters through which a large flow rate of plasma gas can flow, and the flow path for large flow rates composed of the fourth flow path and the second flow path. A large flow rate of plasma gas 4 flows therethrough. A gas purge is performed by the plasma gas 4 having a large flow rate.

時刻ｔ２乃至ｔ６の動作は実施の形態１と同様であるので説明を省略する。
時刻ｔ７において、作業者は休憩又は昼食等で溶接作業を中断して、現場を離れるので、同図（Ｃ）に示すように、パイロットアーク起動スイッチをＯＦＦにする。しかし、同図（Ａ）に示すように、メインスイッチがＯＮ状態で、同図（Ｂ）に示すように、ガスパージ／プロセス切替えスイッチがプロセス側なので、待機期間に入る。
この待機期間では、同図（Ｊ）に示すように、電子式流量調整器２８に入力される流量設定信号を少流量のプラズマガス４を供給する信号に切換えて、第４の流路２２を通って少流量のプラズマガス４を流す。この少流量のプラズマガス４によってガスホース７内に浸透してくる水分をガスパージさせることができる。 Since the operation from time t2 to t6 is the same as that of the first embodiment, the description thereof is omitted.
At time t7, the operator interrupts the welding operation at break or lunch and leaves the site, so the pilot arc starting switch is turned OFF as shown in FIG. However, as shown in FIG. 6A, the main switch is in the ON state, and as shown in FIG. 4B, the gas purge / process changeover switch is on the process side, so the standby period starts.
In this standby period, as shown in FIG. 6J, the flow rate setting signal input to the electronic flow rate regulator 28 is switched to a signal for supplying a small flow rate of the plasma gas 4, and the fourth flow path 22 is changed. A small flow rate of plasma gas 4 is passed through. Moisture permeating into the gas hose 7 can be gas purged by this small flow rate of the plasma gas 4.

時刻ｔ８において、作業者が現場に戻り、同図（Ｃ）に示すように、パイロットアーク起動スイッチをＯＮにし、同図（Ｉ）に示すように、電子式流量調整器２８に入力される流量設定信号をプラズマ溶接に適した中流量のプラズマガスが流れる信号に切換えて、時刻ｔ９からｔ１０において、時刻ｔ３からｔ４までの動作と同じ動作を行って、溶接作業を終了する。 At time t8, the operator returns to the work site, turns on the pilot arc start switch as shown in FIG. 8C, and the flow rate input to the electronic flow regulator 28 as shown in FIG. The setting signal is switched to a signal through which a medium-flow plasma gas suitable for plasma welding flows, and from time t9 to t10, the same operation as that from time t3 to t4 is performed, and the welding operation is completed.

時刻ｔ１１において、同図（Ｃ）に示すように、パイロットアーク起動スイッチをＯＦＦにすると、時刻ｔ７のときと同じように、待機期間に入り、同図（Ｉ）に示すように、電子式流量調整器２８に入力される流量設定信号を少流量のプラズマガス４を供給する信号に切換えて、第４の流路２２を通って小流量のプラズマガス４を流す。この少流量のプラズマガス４によってガスホース７内に浸透してくる水分をガスパージによって放出させる。
時刻ｔ１２において、同図（Ａ）に示すように、メインスイッチをＯＦＦにすると、同図（Ｉ）に示すように、電子式流量調整器２８に入力される流量設定信号が停止して、小流量のプラズマガス４の流れが停止する。 At time t11, when the pilot arc start switch is turned off as shown in FIG. 10C, a standby period is entered as in time t7, and as shown in FIG. The flow rate setting signal input to the regulator 28 is switched to a signal for supplying a low flow rate plasma gas 4, and a low flow rate plasma gas 4 is caused to flow through the fourth flow path 22. Moisture permeating into the gas hose 7 by this small flow rate of the plasma gas 4 is released by gas purge.
At time t12, when the main switch is turned off as shown in FIG. 9A, the flow rate setting signal input to the electronic flow regulator 28 is stopped as shown in FIG. The flow of the plasma gas 4 at a flow rate is stopped.

図４に示した本発明の実施の形態２のプラズマ溶接装置においては、第１の電磁弁２１を設けているが、電子式流量調整器２８に入力される流量設定信号が零のときに、電子式流量調整器２８が閉じるものを使用するときは、第１の電磁弁２１を設ける必要は無い。 In the plasma welding apparatus of the second embodiment of the present invention shown in FIG. 4, the first electromagnetic valve 21 is provided. When the flow rate setting signal input to the electronic flow rate regulator 28 is zero, When the electronic flow regulator 28 is closed, it is not necessary to provide the first electromagnetic valve 21.

また、電子式流量調整器２８の流量を広範囲に亘って調整できるものを使用するときは、第２の電磁弁２３を設けずに、ガスパージ期間に電子式流量調整器２８の流量設定信号を大流量のプラズマガス４を流すことができる信号に切換えてガスパージを行っても良い。 Also, when using a device that can adjust the flow rate of the electronic flow regulator 28 over a wide range, the flow rate setting signal of the electronic flow regulator 28 is increased during the gas purge period without providing the second solenoid valve 23. The gas purge may be performed by switching to a signal that can flow the plasma gas 4 at a flow rate.

本発明の実施の形態２のプラズマ溶接装置は、実施の形態１の効果に加えて、電子式流量調整器２８に入力される流量設定信号を変更することによって、プラズマガス４の流量を容易に調整することができ、より適切なプラズマ溶接を行うことができる。 In addition to the effects of the first embodiment, the plasma welding apparatus according to the second embodiment of the present invention easily changes the flow rate of the plasma gas 4 by changing the flow rate setting signal input to the electronic flow rate regulator 28. It can adjust and can perform more suitable plasma welding.

本発明の実施の形態１のプラズマ溶接装置の構成図である。It is a block diagram of the plasma welding apparatus of Embodiment 1 of this invention. 本発明の実施の形態１のプラズマ溶接装置のタイムチャートである。It is a time chart of the plasma welding apparatus of Embodiment 1 of this invention. 流量と露点が−６０℃を下回るまでの時間との関係を示す図である。It is a figure which shows the relationship between a flow rate and time until a dew point falls below -60 degreeC. 本発明の実施の形態２のプラズマ溶接装置の構成図である。It is a block diagram of the plasma welding apparatus of Embodiment 2 of this invention. 本発明の実施の形態２のプラズマ溶接装置のタイムチャートである。It is a time chart of the plasma welding apparatus of Embodiment 2 of this invention. 従来技術におけるプラズマ溶接装置の構成図である。It is a block diagram of the plasma welding apparatus in a prior art. ガスパージ作業を行ったときのガスパージ時間（横軸）と露点の変化（縦軸）を示す図である。It is a figure which shows the gas purge time (horizontal axis) and the change (vertical axis) of a dew point when performing a gas purge operation.

Explanation of symbols

１プラズマトーチ
２母材
３主プラズマアーク
４プラズマガス
５シールドガス
６プラズマガスボンベ
７ガスホース
８プラズマ溶接電源
９プラズマガス流路
１０プラズマガス流量調整器
１１電極
１２プラズマノズル
１３シールドガスカップ
１４プラズマガス電磁弁
１５シールドガスボンベ
１６シールドガス流路
１７シールドガス流量調整器
１８シールドガス電磁弁
１９第１の流路
２０プラズマガス流量調整器
２１第１の電磁弁
２２第２の流路
２３第２の電磁弁
２４第３の流路
２５第３の電磁弁
２６プラズマ溶接電源
２７第４の流路
２８電子式流量調整器
２９プラズマ溶接電源
DESCRIPTION OF SYMBOLS 1 Plasma torch 2 Base material 3 Main plasma arc 4 Plasma gas 5 Shield gas 6 Plasma gas cylinder 7 Gas hose 8 Plasma welding power source 9 Plasma gas flow path 10 Plasma gas flow regulator 11 Electrode 12 Plasma nozzle 13 Shield gas cup 14 Plasma gas solenoid valve 15 shield gas cylinder 16 shield gas channel 17 shield gas flow rate regulator 18 shield gas solenoid valve 19 first channel 20 plasma gas flow rate regulator 21 first solenoid valve 22 second channel 23 second solenoid valve 24 Third flow path 25 Third electromagnetic valve 26 Plasma welding power supply 27 Fourth flow path 28 Electronic flow regulator 29 Plasma welding power supply

Claims

In a plasma welding power source equipped with a plasma gas flow rate adjusting mechanism provided with a single flow path for adjusting the flow rate of plasma gas supplied to the plasma torch to generate a plasma arc,
Instead of the plasma gas flow rate adjusting mechanism provided with the one flow channel, a large flow rate channel for flowing a preset large flow rate plasma gas, and a medium flow rate channel for flowing a preset medium flow rate plasma gas, Equipped with a plasma gas flow rate adjusting mechanism,
When the main switch is turned ON, the large flow rate plasma gas is supplied through the large flow rate channel,
When the pilot arc start switch is turned on, the medium flow plasma gas is supplied through the medium flow passage,
Thereafter, the plasma welding power source continues to supply the medium-flow plasma gas until the main switch is turned off regardless of whether the pilot arc starting switch is turned off or on.

A small flow passage for flowing a preset small flow plasma gas is added to the plasma gas flow adjustment mechanism, and the small flow passage is provided until the pilot arc start switch is turned off and then on again. 2. The plasma welding power source according to claim 1, wherein the plasma gas is supplied at a small flow rate.

The plasma gas flow rate adjusting mechanism is provided with a first solenoid valve and a plasma gas flow rate regulator that has been adjusted in advance so as to flow the medium flow rate plasma gas in series, and has an inner diameter capable of flowing the large flow rate plasma gas. A first flow path and a second flow path connected to the plasma gas flow controller in parallel with an inner diameter capable of flowing the large flow rate plasma gas by providing a second solenoid valve;
When the main switch is turned on, the first solenoid valve and the second solenoid valve are opened, and the large flow rate channel including the first channel and the second channel is passed through the large flow rate channel. Supplying a flow of plasma gas,
When the pilot arc start switch is turned on, the second electromagnetic valve is closed and the medium flow rate plasma gas is supplied through the medium flow rate flow path including the first flow path.
2. The plasma welding power source according to claim 1, wherein the medium flow plasma gas is continuously supplied until the main switch is turned off regardless of whether the pilot arc starting switch is turned off or on.

The plasma gas flow rate adjusting mechanism is provided with a third solenoid valve, and has an inner diameter that allows a small flow rate of plasma gas to flow, and the plasma gas flow rate regulator and the first solenoid valve in the first flow path, Add a third channel connected in parallel,
The first solenoid valve is closed and the third solenoid valve is opened until the pilot arc start switch is turned on again and then the third solenoid valve is opened, and the small flow rate plasma gas is passed through the third flow path. The plasma welding power source according to claim 3, wherein the plasma welding power source is supplied.

The plasma gas flow rate adjusting mechanism is provided with a first solenoid valve and an electronic flow rate regulator for adjusting the flow rate of the plasma gas by a flow rate setting signal in series, and has an inner diameter capable of flowing the high flow rate plasma gas. 4 and a second electromagnetic valve provided with a second electromagnetic valve and having an inner diameter capable of flowing the large flow rate plasma gas and connected in parallel with the electronic flow regulator,
When the main switch is turned ON, the first solenoid valve and the second solenoid valve are opened, and the flow rate setting signal is made a signal for flowing the medium flow rate plasma gas, and the fourth flow path and the second Supplying the large flow rate plasma gas through the large flow rate flow path comprising
When the pilot arc start switch is turned ON, the second electromagnetic valve is closed and the medium flow rate plasma gas is supplied through the medium flow rate flow path including the fourth flow path.
2. The plasma welding power source according to claim 1, wherein the medium flow plasma gas is continuously supplied until the main switch is turned off regardless of whether the pilot arc starting switch is turned off or on.

The flow rate setting signal is switched to a signal for flowing the plasma gas at a small flow rate until the pilot arc start switch is turned on again after the pilot arc start switch is turned on, and the plasma gas at the small flow rate is supplied through the fourth flow path. 6. The plasma welding power source according to claim 5, wherein: