ARRANGEMENT FOR IMPROVING ESPECIALLY JOB AND FIRE SAFETY IN GAS-SHIELDED ARC WELDING

Abstract: Arrangement especially in order to improve job and fire safety by gas-shielded welding using a welding equipment including a welding machine (1), a shielding gas unit (4) and a hand-held nozzle part (3) connected by means of a soft pipe unit (2) to welding machine (1), whereat the welding rod (L) is arranged to become melted onto the welding spot by means of a flame arc in connection with nozzle part (3). The welding equipment includes in the first plate a coupling arrangement (X) for conveyance of shielding gas in protection situation from shielding gas unit (4) to the spot exposed to fire risk/burning with a substantially greater volume flow than the welding procedure, most suitably through nozzle part (3) along soft pipe unit (2) and, on the other hand, a discharge arrangement (5) to remove shielding gases by suction, substantially off contact from the nozzle part (3), by means of a suction apparatus (8), or by means of built-in suction duct (5a) and/or suction arrangement (5a') arranged in soft pipe unit (2) and/or in nozzle part (3).

Description: Arrangement for improving especially job and fire safety in gas-shielded arc welding The invention relates to an arrangement especially in order to improve job and fire safety by gas-shielded welding using a welding equipment including a welding machine, a shielding gas unit and a hand-held nozzle part connected by means of a soft pipe unit to the welding machine, whereat the welding rod is arranged to become melted onto the welding spot by means of a flame arc in connection with the nozzle part, while being protected by shielding gas from the shielding gas unit. In addition, and especially in order to improve job and fire safety, the welding equipment includes in the first place a coupling arrangement for conveyance of shielding gas in the protection situation from the shielding gas unit to the spot exposed to fire risk/burning by actuators arranged activated most suitably by means of a switch, for instance a push button or similar, connected to the nozzle part, in order to cut-off at least the supply of welding current to the nozzle part and to convey shielding gas with a substantially greater volume flow than the welding procedure, most suitably through the nozzle along the soft pipe unit and, on the other hand, a discharge arrangement to remove shielding gases by suction, substantially off contact from the nozzle part, by means of a suction apparatus, e.g. an exhauster, a fan and/or similar, or by means of a built-in suction duct and/or a suction arrangement in the soft pipe unit and/or in the nozzle part. The way of welding described above corresponds to e.g. the so called TIG-welding used most commonly e.g. for welding of thin sheet metal, for instance in garages. The above type of working can also be utilized in connection with the so called MIG-welding, whereby the welding machine also has a unit for rod supply and means for adjustment of the rod feed speed. Then the feeding of welding rod from the supply unit through the nozzle part to the welding point is also arranged by means of the soft pipe unit. The Finnish application FI 94514 and the application document DE 3 404 614 disclose the type of solutions above, especially intended for improvement of job and fire safety during the process of welding. Known from the solutions above is that to a spot exposed to fire risk/burning shielding gas is conveyed from a shielding gas unit, mainly included in a so called MIG- welding apparatus, and through a nozzle part, advantageously by means of actuators operated by a switch in the nozzle part, which and cut-off the welding current and feed of welding rod and, in cases of disturbance, switch on the volume flow of shielding gas, conveyed through the nozzle, at a substantially higher rate than the flow used by welding. Presently, improved welding devices are used, where welding gases can be discharged by suction through the nozzle part and by the impact of an exhauster connected to a built-in suction duct in the soft pipe unit. Neither solution in the above publications FI 94514 and DE 3 404 614, as far as the technical implementation is concerned, and also therefore, presents any advantageous solutions with respect to the manufacturing costs since, in the first place, in both of them internal flow-technical couplings are always required. This, of course, calls mostly for co-operation with the manufacturers of welding equipment, which in the practice tends to increase the production costs of machines. Furthermore, in solutions of this kind, it is most complicated to make existing welding equipment more safe in accordance with the above mentioned solutions . On the other hand, in the Finnish patent application number 970758 an improved solution is presented, especially with an eye on the above mentioned problems and based on the fact that the flow arrangement included in the coupling arrangement is carried out, flow-technically taken, substantially from the outside by conveying shielding gas in a conventional welding- stopping protective situation, e.g. fire smouldering from the shielding gas unit directly past the welding apparatus to the nozzle part. The advantage of this solution is the simplicity of its technical implementation, thanks to which it is also possible to make existing welding devices more safe by quite simple supplementary assemblies . Then, as an advantageous application, prevention of a fire situation can take place more rapidly only using the switch in the nozzle part, whereby actuators operated by it cut-off, e.g. by MIG-welding, in such a protection situation the supply of welding current and welding rod feed to the nozzle and at the same time switch on higher rate of shielding gas flow to the nozzle part than the flow of the welding procedure. As to the welding arrangement of the said patent application 970758, in spite of its indisputable advantages and practical success, further demand has been, however, noted especially for intensification of the shielding gas flow in a protection situation, since in utilizing the said welding arrangement one has to limit oneself in the soft pipe unit and the nozzle part to shielding gas flow channels with relative small cross-cuts, since in practice they are dimensioned mainly according the requirements of the welding situation. Accordingly, in the actual protecting situation one has to use, in order to secure sufficient extinction capacity, quite great speeds of flow causing both pressure losses and noise pollution. The arrangement now presented, especially for improvement of job and fire safety by gas-shielded welding, is intended to get rid of problems presented above and thus to increase, significantly, the techniques of prior art in the field. In order to reach this aim, the arrangement of this invention is mainly characterized in that the arrangement includes means for conveyance of shielding gas or compressed air in a protecting situation through a suction duct and/or a suction arrangement at least partly included in the discharge arrangement and/or nozzle part. As the most important advantages of the arrangement according to this invention can be mentioned its simplicity and efficiency, whereby any now existing welding equipment having an integrated discharge arrangement can with guite few additional assemblies be completed also by an effective fire preventing arrangement. Particularly, this is due to the fact that on conveying shielding gas or compressed air in a protection situation through a suction duct, included in the discharge arrangement, then for the feed of shielding gas or compressed air the greatest possible cross-sectional area of the soft pipe unit and the nozzle part is available. It is in a situation of protection then possible to arrange the output of shielding gas to the optimal, reducing at the same time, however, pressure losses and eliminating noise pollution. On the other hand, it is possible to vary the arrangement according to the invention, in the first place, so that the places of the shielding gas feeding arrangement and secondly the places of the suction arrangement, discharging welding gases, are modified in regard to the conventional embodiment so that the suction arrangement is taken from the shielding gas inside. Then, on the other hand, the arrangement of the invention is implemented so that in the protection situation for the shielding gas feed both the suction duct of the flow channel of shielding gas and of the discharge arrangement are used, thus achieving a double effect so that welding becomes more effective, sinpe combustion gas produced by welding is suctioned as close a distance as possible from the place it is generated, and on the other hand, so that the welding spot is completely surrounded by shielding gas . Then the output of shielding gas is in a protecting situation at its maximum, because the cross-sectional area used for it is the largest possible both in the soft pipe unit and in the nozzle part. Advantageous applications of the arrangement according to the invention are presented in the dependent claims regarding the arrangement . In the following the invention is disclosed with reference to the enclosed drawing, where Fig. 1 shows an advantageous implementation principle of the arrangement according to the invention, Fig. 2a and 2b show lengthwise profiles of some details in the arrangement, and Fig. 3 shows a lengthwise profile one detail in the arrangement according to the invention in connection with the nozzle part. The object of the inventions is an arrangement particularly for improvement of job and fire safety by gas-shielded welding using a welding apparatus comprising a welding machine 1, a shielding gas unit 4 and a hand-held nozzle part 3 connected to welding machine 1 by means of a soft pipe unit 2, whereby welding rod L is arranged, using trigger B in nozzle part 3, to become melted onto the welding spot 3, by a flame arc in connection with nozzle part while protected by shielding gas conveyed from shield gas unit 4. In addition, in order to improve the job and fire safety at welding, the welding equipment includes in, the first place, a coupling arrangement X for conveyance of shielding gas or compressed air from the shielding gas unit 4 in the protection situation to a spot exposed to fire risk/burning by means of actuators arranged most suitably to be activated by means of switch XI, for instance a push button or similar, in the nozzle part, to cutoff at least the supply of welding current to nozzle part 3 and to convey shielding gas or compressed air with a volume flow substantially greater than the welding procedure, most suitably through the nozzle by means of soft pipe unit 2 and on the other hand, a discharge arrangement 5 for removal of shielding gases by suction, substantially off contact from nozzle part 3 by means of a suction apparatus 8, e.g. an exhauster, a fan and/or similar, connected to the discharge channel 5; 5b through a built-in suction duct 5a and/or suction arrangement 5a' arranged in soft pipe unit 2 and/or in nozzle part 3. For instance, according to the principle presented in figures 1 and 2a, said means comprise a control unit C advantageously arranged, with regard to a protection situation, in connection with soft pipe unit 2 and intended, in the first place, to cut-off the suction flow in suction duct 5a and/or in suction arrangement 5a' and, on the other hand, to feed shielding gas and/or compressed air into it/them. In this connection the control unit C is advantageously arranged into contact with end I connected to welding machine 1 of soft pipe unit 2, while the operation means C are controlling its function, for instance starting switch xl of the gas for shielding, most simply in nozzle part 3. With special reference to figure 2a, the control unit C is in protecting situation arranged to cut-off the function of suction equipment 8, for instance of the exhauster, fan or similar, and also the suction flow by means of a valve arrangement 6, closing for instance cut-off valve 6a and/or similar, and let then the shielding gas into suction duct 5a by means of feeding pipe 4a fixed to shielding gas unit 4 while then valve 6b is kept open. Furthermore, the above presented can be put into practice simply so that control unit C carries out all said steps in right order automatically in the way illustrated in figure 2b using starting switch xl only. Still referring to the advantageous application presented in figure 2b, there are in connection with nozzle part 3, e.g. nozzle-neck 3a, regulating members 7, e.g. a regulation valve 6c or similar working by the principle of by-pass flow, and arranged to regulate the flow in suction duct 5a and/or suction arrangement 5a' . With special reference to figure 3, the nozzle arrangement 4c of shielding gas flow and the suction arrangement 5a' of discharge arrangement 5 are especially in nozzle part 3 during welding arranged by radial constructions one on top of another. As an advantageous application of the invention is that both the suction duct 5a and the suction arrangement 5a' joined to it in the soft pipe unit " 2 in the nozzle part 3 outer end are in protection situation advantageously placed in soft pipe line from the inside to in the flow channel that conveys shielding gas and in the nozzle part 3 to nozzle arrangement 4c that feeds shielding gas, whereby in the protection situation shielding gas is arranged to get advantageously conveyed along soft pipe line 2 and nozzle part 3 through both the flow channel of shielding gas and the suction arrangement 4b, 4c as well as the suction duct and suction arrangement 5a, 5a' comprised in discharge arrangement 5. As a basis for this application is, particularly, knowledge depending on experience, that combustion gas generates most strongly when hot sparks from the welding spot get in direct contact with open air. This problem can be efficiently reduced, in the first place, since suction produced by the suction arrangement is immediately aimed at the welding spot, . in addition to which both the welding spot and said suction arrangement is on the welding spot completely surrounded by shielding gas. Evidently, the invention is not restricted to the above illustrated or presented applications but can quite significantly be modified within the limits of the basic idea. It is obvious, of course, that it is possible to apply the simple principle according to the invention also to another kind of welding, where almost any gas or compressed air is used in one form or another and, in addition, also a discharge arrangement, which both are implemented to take place substantially through the soft pipe line and/or the nozzle part. It is, of course possible to arrange e.g. the actuators to work by medium using some kind of mechanical e.g. spring solutions or even applying the latest wireless techniques, utilizing e.g. components of radio frequency. However, the operational reliability of the above said may as practical applications be more uncertain compared with so called traditionally implemented electric arrangements, and also require much more service and maintenance than conventional constructions. Furthermore, the operating members and regulating members of the arrangement of this invention can, of course, be integrated to one and the same regulator or in some other way arranged, e.g. with separate manual push buttons or "triggers" etc.

Claims: CLAIMS 1. Arrangement especially in order to improve job and fire safety by gas-shielded welding using a welding equipment including a welding machine (1) , a shielding gas unit (4) and a hand-held nozzle part (3) connected by means of a soft pipe unit (2) to welding machine (1) , whereat the welding rod (L) is arranged to become melted onto the welding spot by means of a flame arc in connection with nozzle part (3) , while being protected by shielding gas from shielding gas unit (4) . In addition, and especially in order to improve job and fire safety, the welding equipment includes in the first place a coupling arrangement (X) for conveyance of shielding gas in protection situation from shielding gas unit (4) to the spot exposed to fire risk/burning by actuators arranged most suitably to get activated by means of a switch (XI), for instance a push button or similar, connect nozzle part (3) , to cut-off at least the supply of welding current to the nozzle part (3) and to convey shielding gas and/or compressed air with a substantially greater volume flow than the welding procedure, most suitably through nozzle part (3) along soft pipe unit (2) and, on the other hand, a discharge arrangement (5) to remove shielding gases by suction, substantially off contact from the nozzle part (3), by means of a suction apparatus (8), e.g. an exhauster, a fan and/or similar, or by means of built-in suction duct (5a) and/or suction arrangement (5a) ' arranged in soft pipe unit (2) and/or in nozzle part (3), characterized in that the arrangement includes means to convey in protection situation shielding gas and/or compressed air through suction duct (5a) and/or suction arrangement (5a' ) located at least partly in soft pipe unit (2) or in nozzle part (3) . 2. Arrangement according to claim 1 characterized in that in the protection situation the said means comprise most suitably a control unit in association with soft pipe unit (2), in the first hand to cut-off the suction flow in suction duct (5a') and, on the other hand, to feed shielding gas into it/into them. 3 Arrangement according to claim 1 characterized in that control unit (C) is arranged in connection with end I, which is to be connected to welding machine (1) of soft pipe unit (2) , arranged in association with it in nozzle part (3) there are operation members (C ) controlling its function. 4. Arrangement according to any of the above claims 1 - 3 characterized in that control unit (C) is in protection situation arranged to cut-off suction equipment (8), e.g. the function of an exhauster, a fan or similar, to cut-off the suction flow of suction duct (5a) by means of valve arrangement (6), by closing shut-off valve (6a) and/or similar, in order to convey then shielding gas and/or compressed to suction duct (5a) along delivery pipe (4a), fixed to shielding gas unit (4), by opening the function valve in it. 5. Arrangement according to any of the above claims 1 - 4 characterized in that in connection with nozzle part (3) , as nozzle-neck (3a), regulating members (7), e.g. a regulating valve (6c) or similar working with the principle of by-pass flow, are arranged to regulate the flow in suction duct (5a), and/or in suction arrangement (5a'). 6. Arrangement according to any of the above claims 1 - 5, where the nozzle arrangement (4c) of the protection situation and the suction arrangement (5a' ) of discharge arrangement (5) are especially in nozzle part (3) arranged by radial constructions one on top of another, characterized in that suction duct (5a) and suction arrangement (5a) joining it in the outer end of nozzle part (3) are in the during welding from the inside in regard to the shielding gas feeding flow route (4) and to nozzle arrangement (4c) , whereby shield gas is arranged to be conveyed in protection situation by means of soft pipe unit (2) and nozzle part (3) through both the flow route for shielding gas and nozzle arrangement (4b, 4c) as well as the suction duct and suction arrangement (5a, 5a').

Inventors: TAIPALE ASKO, TAIPALE, ASKO
Applicants: TAIPALE ASKO, TAIPALE AUTOMOTIVE OY, TAIPALE, ASKO
Application year: 2001
Main classification: B23K9
IPC codes: B23K9