WO1988006073A1

WO1988006073A1 - A welding gun

Info

Publication number: WO1988006073A1
Application number: PCT/DK1988/000016
Authority: WO
Inventors: Peter Jørgen LUND
Original assignee: Vacumig Aps
Priority date: 1987-02-10
Filing date: 1988-02-09
Publication date: 1988-08-25
Also published as: DK67487D0; AU1340288A; DK67487A

Abstract

A welding gun for electric arc-welding by means of a continuously fed solid metal electrode or a tube wire filled with powder and comprising a sleeve with an inlet opening guiding the electrode, a means driving the electrode, a welding mouthpiece or a welding burner, means feeding protective gases through a gas nozzle, and optionally means (5, 6) cooling the gas nozzle. The gas nozzle is a copper point (12) cast in a body of plastics. The plastic body comprises two substantially concentric tubes interconnected through longitudinal connecting pieces (13), said copper point being cast in the connecting pieces. In this manner a welding mouthpiece is obtained which is less expensive to manufacture than previously known. An additional advantage of this welding mouthpiece is that it can be touched as it is not so hot. In addition it is of a low weight and completely tight due to the casting. Furthermore the mouthpiece need not be insulated.

Description

Title: A Welding Gun

Technical Field

The invention relates to a welding gun for electric arc- welding by means of a continuously fed solid metal electrode or a tube wire filled with powder and comprising a sleeve with an inlet opening guiding the electrode, a means driving the electrode, a welding mouthpiece or a welding burner, means feeding protective gases through a gas nozzle, and optionally means cooling the gas nozzle. The invention is a further development of the welding gun described in the German Patent Application No. 37 02 486.8.

Background Art

Approx. 10 welding mouthpieces are used annually per welding gun. The known welding mouthpieces are relatively expensive to manufacture inter alia because each mouthpiece requires an outer copper tube to be secured on an inner copper tube by means of a plurality of passing screws. Firstly these screws cause a turbulence in the suction channel between the tubes which necessitates a high vacuum, and secondly a risk of leaks exists whereby the protective gas is not completely utilized. In addition, the welding mouthpiece must be screwed on, and an electric isolation must be provided between the thread and the remaining portion of the welding mouthpiece.

Disclosure of Invention

The object of the invention is to avoid these draw-backs, and the welding gun according to the invention is characterised by the welding mouthpiece comprising an intermediary member in the form of a cast body of plastics, such as po lyphenylene sulfide, which is heat-resistant. Upon casting the body is situated in a turning lathe where a circumferential groove is milled and a thread is bored in said cast body. An additional advantage of such a structure is that it can be touched as it is not too hot. In addition it is of a low weight and completely tight due to the casting procedure. Moreover the discarding percentage is minimized.

Furthermore according to the Invention the cast body may comprise two substantially concentric tubes interconnected through longitudinal connecting pieces. As a result the spaces between the tubes can be utilized for exhausting welding smoke. The longitudinal connecting ribs ensure a laminar flow In such a manner that a low vacuum suffizes.

The invention deals furthermore with a method for manufacturing a welding gun. The Intermediary member is according to the invention situated In a turning lathe when cast in the welding mouthpiece, whereafter a circumferential groove is milled and a thread Is bored in the cast body. In this manner several operational steps are combined into one step.

Brief Description of Drawings

The invention will be described below with reference to the accompanying drawings, in which

Fig. 1 illustrates a known welding gun,

Fig. 2 illustrates a welding mouthpiece according to the invention which can be used in connection with the welding gun of Fig. 1,

Fig. 3 is a sectional view taken along the line 1-1 of the welding mouthpiece of Fig. 2,

Fig. 4 Illustrates the welding mouthpiece upon mounting, and

Fig. 5 is a sectional view of the entire welding gun.

Best Mode for Carrying Out the Invention

The welding gun of Fig. 1 forms part of an electric arc- welding system (MIG/MAG -welding). The welding system comprises a delivery roll (not shown) for a wire or band- shaped we l ding e l e c tr o de or a tube wire filled with powder, a sleeve guiding the electrode 1 uncoiled the roll, a means (not shown) advancing the electrode, as well as a contact point. In addition, means are provided which feed protective gases, such as argon, through a gas nozzle surrounding the contact point. The protective gases are fed together with the electrode 1 and delivered through openings 3 in the contact point. Furthermore means are provided which water cool the gas nozzle. The cooling water is carried downwards at a distance of approx. 2 mm from the gas exhaust openings 3. The sectional view A-A shows in addition the channels 5, 6 for the feeding an returning of the cooling water. Conduits 7, 8 feeding welding current are provided in the cooling water channels 5, 6 whereby the cooling allows the use of thin welding conductors. It appears that the tube 9 advancing welding wire 1 and protective gases is partly surrounded by the cooling water channels 5, 6.

Approx. 10 welding mouthpieces are used annually per welding gun. Fig. 2 illustrates a welding mouthpiece according to the invention which comprises an intermediary member 11 of plastics and cast in a copper point 12. The cast plastic body 11 comprises two substantially concentric tubes 1a, 1b, cf. Figs. 2 and 3, which are interconnected through three longitudinal ribs 13, of. Fig. 3. The spaces 14 between the ribs 13 are utilized for exhausting welding smoke through a circumferential groove 15. Upon casting the unit is situated in a turning lathe for milling the circumferential groove 15 between the plastic body 11 and the copper point 12. Furthermore a bore and a thread are provided at 16 in the cast body 11.

In this manner a welding mouthpiece is provided which is less expensive to manufacture than previously. An additional advantage of this welding mouthpiece is that it is not so hot and can therefore be touched. Moreover it is of a low weight, and the casting implies that It is completely tight. Furthermore the mouthpiece according to the invention need not be insulated.

The plastics used is preferably polyphenylene sulfide which is very heat-resistant.

The point 12 is of copper tellurium.

Thus the invention provides a welding gun which is easier to handle and which furthermore requires a lower vacuum than previously.

The welding mouthpiece is of an outer diameter of about 2.5 cm.

Fig. 4 illustrates the welding mouthpiece when secured by way of screwing on the contact point at the thread 16. The mouthpiece abuts closely the branch pipe 22, i.e. the suction pipe, and the welding gun simultaneously. Fig. 5 illustrates the entire welding gun comprising the contact point, the branch pipe 22, a tube 23 surrounding a guide sleeve 24, a junction pipe 25, a cover or screen 26, a contact insert 27, a contact spring 28, an insulating pipe 29, a control conduit 30, a handle 31, and an operator button 32.

Claims

Claims:

1. A welding gun for electric arc-welding by means of a continuously fed solid metal electrode or a tube wire filled with powder and comprising a sleeve with an inlet opening guiding the electrode, a means driving the electrode, a welding mouthpiece or a welding burner, means feeding protective gases through a gas nozzle, and optionally means cooling the gas nozzle, c h a r a c t e r i s e d by the gas nozzle comprising an intermediary member (11) in the form of a cast body of plastics.

2. A welding gun as claimed in claim 1, c h a r a c t e r i s e d by the cast body (11) comprising two substantially concentric tubes interconnected through longitudinal connecting pieces (13).

3. A welding gun as claimed in claim 2, c h a r a c t e r i s e d by the welding mouthpiece (12) being cast in the connecting pieces (13).

4. A welding gun as claimed in claims 1 to 3 , c h a ra c t e r i s e d by the plastics being polyphenylene sulfide.

5. A welding gun as claimed in claims 1 to 4, c h a ra c t e r i s e d by a circumferential groove being provided in the cast body and communicating with the spaces (14) between the two tubes.

6. A method for manufacturing a welding gun according to claim 1, c h a r a c t e r i s e d by the intermediary member (11) being situated in a turning lathe when cast in the welding mouthpiece (12), whereafter a circumferential groove (15) is milled and a thread (at 16) is bored in the cast body.

7. A welding gun substantially as described above and with reference to the accompanying drawings.

8. A welding mouthpiece substantially as described above and with reference to the accompanying drawings.