Plasma torch for cutting use with nozzle protection cap having annular secondary GPS passage and insulator disposed in the secondary gas passage

A plasma torch for cutting use comprising:

• a torch body having an axis;
• an electrode arranged in the torch body, said electrode having a cooling water chamber therein;
• nozzle means arranged outside the electrode for covering the electrode, with a plasma gas passage formed therebetween, said nozzle means being provided with a nozzle orifice;
• a nozzle cap for covering the nozzle means;
• a nozzle protection cap having a front end side with an opening opposing the orifice of the nozzle means, said nozzle protection cap being disposed outside the nozzle cap with an annular secondary gas passage therebetween communicating with the opening, said nozzle protection cap being electrically insulated from the electrode and the nozzle means, said nozzle protection cap having a base end portion with a double wall structure defining a space formed as an annular cooling water chamber which is in communication with the cooling water chamber formed inside the electrode;
• and
• an insulator disposed in the secondary gas passage and formed of an electrically insulating material, said insulator having a rectifying passage for rectifying a gas flow passing through the secondary gas passage;
• a plasma gas passage;
• and
• a plasma gas flow-in passage, formed around the electrode in an inclined manner with respect to said axis of the torch body, said plasma gas flow-in passage being arranged for introducing plasma gas into said plasma gas passage and for imparting a gyrating flow to the introduced plasma gas;
• wherein said rectifying passage of the insulator is formed to provide a spiral shape for imparting a gyrating flow, in the same direction as the gyrating flow of the plasma gas, to the secondary gas passing through the rectifying passage;
• and
• wherein a relationship between the orifice length L and the orifice diameter .PHI..sub.1 is satisfied by L/.PHI..sub.2 .ltoreq.2.

A plasma torch for cutting use comprising:

• a torch body having an axis;
• an electrode arranged in the torch body;
• nozzle means arranged outside the electrode for covering the electrode, with a plasma gas passage formed therebetween, said nozzle means being provided with a nozzle orifice;
• a nozzle cap for covering the nozzle means;
• a nozzle protection cap having a front end side with an opening opposing the orifice of the nozzle means, said nozzle protection cap being disposed outside the nozzle cap with an annular secondary gas passage therebetween communicating with the opening, said nozzle protection cap being electrically insulated from the electrode and the nozzle means;
• and
• an insulator disposed in the secondary gas passage and formed of an electrically insulating material, said insulator having a rectifying passage for rectifying a gas flow passing through the secondary gas passage;
• a plasma gas passage formed around the electrode;
• plasma gas flow-in passage, formed around the electrode in an inclined manner with respect to said axis of the torch body, for introducing plasma gas into said plasma gas passage and for imparting a gyrating flow to the introduced plasma gas;
• and
• said rectifying passage of the insulator being formed to provide a spiral shape for imparting a gyrating flow, in the same direction as the gyrating flow of the plasma gas, to the secondary gas passing through the rectifying passage.

A plasma torch for cutting use comprising:

• a torch body having an axis;
• an electrode arranged in the torch body;
• nozzle means arranged outside the electrode for covering the electrode, with a plasma gas passage formed therebetween, said nozzle means being provided with a nozzle orifice;
• a nozzle cap for covering the nozzle means;
• a nozzle protection cap having a front end side with an opening opposing the orifice of the nozzle means, said nozzle protection cap being disposed outside the nozzle cap with an annular secondary gas passage therebetween communicating with the opening, said nozzle protection cap being electrically insulated from the electrode and the nozzle means, said nozzle protection cap being provided with a front end portion for protecting a front end portion of the nozzle means and a base end portion secured to the torch body, said front end portion and said base end portion being detachably coupled together;
• an insulator disposed in the secondary gas passage and formed of an electrically insulating material, said insulator having a rectifying passage for rectifying a gas flow passing through the secondary gas passage;
• a plasma gas passage;
• and
• a plasma gas flow-in passage, formed around the electrode in an inclined manner with respect to said axis of the torch body, said plasma gas flow-in passage being arranged for introducing plasma gas into said plasma gas passage and for imparting a gyrating flow to the introduced plasma gas;
• wherein said rectifying passage of the insulator is formed to provide a spiral shape for imparting a gyrating flow, in the same direction as the gyrating flow of the plasma gas, to the secondary gas passing through the rectifying passage;
• and
• wherein a relationship between the orifice length L and the orifice diameter .PHI..sub.1 is satisfied by L/.PHI..sub.1 .ltoreq.2.

A plasma torch for cutting use comprising:

• a torch body;
• an electrode arranged in the torch body;
• nozzle means arranged outside the electrode for covering the electrode, with a plasma gas passage formed therebetween, said nozzle means being provided with a nozzle orifice;
• a nozzle cap for covering the nozzle means;
• a nozzle protection cap having a front end side with an opening opposing the orifice of the nozzle means, said nozzle protection cap being disposed outside the nozzle cap with an annular secondary gas passage therebetween communicating with the opening, said nozzle protection cap being electrically insulated from the electrode and the nozzle means;
• an insulator disposed in the secondary gas passage and formed of an electrically insulating material, said insulator having a rectifying passage for rectifying a gas flow passing through the secondary gas passage;
• and
• said nozzle having a front end surface opposing a distal end of said front end side of the nozzle protection cap through a gap therebetween, said gap having a dimension h of 0.5-1.5 mm in order to increase the assist gas flow rate.

A plasma torch for cutting use comprising:

• a torch body;
• an electrode arranged in the torch body;
• nozzle means arranged outside the electrode for covering the electrode, with a plasma gas passage formed therebetween, said nozzle means being provided with a nozzle orifice;
• a nozzle cap for covering the nozzle means;
• a nozzle protection cap having a front end side with an opening opposing the orifice of the nozzle means, said nozzle protection cap being disposed outside the nozzle cap means with an annular secondary gas passage therebetween communicating with the opening, said nozzle protection cap being electrically insulated from the electrode and the nozzle means;
• an insulator disposed in the secondary gas passage and formed of an electrically insulating material, said insulator having a rectifying passage for rectifying a gas flow passing through the secondary gas passage;
• and
• a ratio .PHI..sub.2 /.PHI..sub.1 between an orifice diameter .PHI..sub.1 of the nozzle and an opening diameter .PHI..sub.2 of the nozzle protection cap being set to 1.0-5.0.