Abstract:
A welding ( 10 ) for use with gas metal arc welding wherein the welding head ( 10 ) has a diffuser body ( 16 ) with an inlet end ( 28 ) and an outlet end ( 38 ). A welding tip ( 14 ) is axially located within the diffuser body ( 16 ) and extends axially beyond the outlet end ( 38 ). The diffuser body ( 16 ) has a gas outlet ( 37 ) and a gas inlet ( 34 ), and there is at least one gas channel ( 36 ) operatively connecting the gas inlet ( 34 ) and the gas outlet ( 37 ). One or more diffusing lenses ( 20 ) are provided between the gas outlet ( 37 ) and the outlet end ( 38 ).

Description:
FIELD OF THE INVENTION 
     This invention relates to welding equipment and refers particularly, though not exclusively, to a welding head for use with gas metal arc welding, also known as metal inert gas welding. 
     BACKGROUND OF THE INVENTION 
     With gas metal arc welding, an inert gas is passed over the welding rod during the welding process so as to eliminate oxygen from the area of the weld. The presence of oxygen deteriorates the quality of the weld, and leads to imperfections in the welding. The presence of an inert gas, such as carbon dioxide or argon, eliminates the oxygen from the site and therefore enables proper welding. Gas metal arc welding is used with material such as, for example, stainless steel. 
     With present equipment, a welding head is used which has radially directed outlets in the diffusion body for the gas. This creates a turbulent flow within the nozzle and thus the gas exits the nozzle in a turbulent manner. This causes the gas to encapsulate some oxygen, which can lead to small, localised faults in the welding. It can also cause spluttering and inconsistent welding performance. 
     The significant problem with a turbulent flow is that it makes the gas very susceptible to being deviated from its intended path by external factors such as winds, breezes, or other forms of air flow. Therefore, in many instances, large shields are placed around the welding site in an attempt to eliminate, or at least reduce, unwanted air flows to thus enable welding to continue. However, this cannot be readily achieved in many situations such as, for example, large factories, or welding in the open. Therefore, there is significant loss of gas, loss of efficiency, and loss of productive work time. This has increased the cost of such welding, and reduced the reliability of such welding, to a significant extent. 
     It is therefore the principle object of the present invention to provide welding equipment, particularly for use in gas metal arc welding, whereby the gas flow is more controlled and is therefore less susceptible to deviation from its intended path by air flow. 
     A further object of the present invention is to provide welding equipment, particularly for use with gas metal arc welding, where the gas flow is more even and less turbulent and therefore has a reduced tendency to entrap air. 
     SUMMARY OF THE INVENTION 
     With the above and other objects in mind the present invention provides a welding head for use with gas metal arc welding wherein the welding head has a diffuser body with an inlet end and an outlet end, there being a welding tip axially located within the diffuser body and extending axially beyond the outlet end, the diffuser body having a gas outlet and a gas inlet, there being at least one gas channel operatively connecting the gas inlet and the gas outlet, there being provided one or more diffusing lenses between the gas outlet and the outlet end. 
     Preferably, the gas channel includes a plurality of axially aligned channels arranged in a regular array around the longitudinal axis of the diffuser body. Alternatively, the gas channel is a single opening along the longitudinal axis of the diffuser body. 
     Preferably, the diffusing lenses are co-axial with the welding tip, the welding tip passing through a central aperture in each of the diffusing lenses. 
     Preferably, there are at least two diffusing lenses, separated by a spacer ring. 
     The diffusing lenses may be of different porosities. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     In order that the invention may be fully understood there shall now be described preferred constructions of welding equipment incorporating the principle features of the present invention, the description being by way of non-limitative example only and being with reference to the accompanying illustrative drawings in which: 
     FIG. 1 is a front perspective view of a welding head incorporating the principle features of the present invention; 
     FIG. 2 is an exploded perspective view of the welding head of FIG. 1; 
     FIG. 3 is a longitudinal cross-sectional view of the welding head of FIGS. 1 and 2; 
     FIG. 4 is a front perspective view of a second form of welding head incorporating the principle features of the present invention; 
     FIG. 5 is an exploded perspective view of the welding head of FIG. 4; 
     FIG. 6 is a longitudinal cross-sectional view of the diffuser body of the welding head of FIGS. 4 and 5; and 
     FIG. 7 is a front end view of the diffuser body of FIG.  6 . 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     To firstly refer to the embodiment of FIGS. 1-3, there is shown a welding head generally designated as  10  and which has a nozzle  12 , welding tip  14 , diffuser body  16 , gasket  18 , two diffusing lenses  20 , spacer  22 , and circlip  24 . 
     The diffuser body  16  is shaped somewhat like a hollow cylinder. On its external surface  24  it has a threaded portion  26 . Extending rearwardly from the diffuser body  16  is the inlet end  28  which again has an outer surface  30  with a threaded portion  32 . Both the portion  28  and diffuser body  16  are hollow so that an inert gas such as argon or carbon dioxide can pass thereinto and therethrough. 
     The inlet end  28  of diffuser body  16  has inlet ports  34  which lead to elongate channels  36  in the diffuser body  16 . The inert gas can pass through the inlet  34  and into the elongate channels  36  and thereby to outlets  37 . From there it can pass through the outlet end  38  of the diffuser body  16 . 
     The welding tip  14  has a central opening  40  into which a welding rod can be located or through which a continuous welding wire may pass. 
     Located between outlet end  38  of diffuser body  16  and outlets  37  are a plurality, preferably two, diffuser lenses  20 . A spacer  22  in the form of a thin ring is used to space the two diffusing lenses  20 . A circlip  24  is used to hold the diffusing lenses  20  in position relative to the diffuser body  16 . The diffusing lenses  20  are porous such that the inert gas can pass therethrough, but at a controlled rate. It is preferable that the first of the lenses  21  is of a reduced porosity compared to the second lens  23 . For example, the first lens may be in the range of 50-150 microns, preferably 75-125 microns, more preferably 100 microns. The second diffusing lens  23  may be in the range 40-100 microns, preferably 50-70 microns, more preferably 60 microns. In this way, the first lens  21  creates a back-pressure in the inert gas, which can then pass through the lens  21 , but through the second lens  23  more easily. 
     By using porous diffusing lenses  20 , a multitudinous number of openings are created through which the gas passes. By virtue of the nature of those lenses, the gas flow through each of the openings in the lenses  20  resembles that of a nozzle so that the gas passes through with substantive pressure behind it, and in a clear and unified direction axially. It is not a turbulent flow. Therefore, the probability of entrapping air in the gas flow is significantly reduced. Furthermore, the susceptibility of the gas flow to diversion due to air flow is also significantly reduced. 
     It has been found that by using the present invention, the consumption of the inert gas may be reduced from between 50-30%. In a normal welding situation, a bottle of inert gas would normally last one day for one welder. At a cost of AU$100 per bottle, that would represent a saving of between $30 and $50 per day, per welder. 
     As can be seen from FIG. 3, the diffuser body  16  has a face  42  in which the gas outlets  37  are located. It is preferable that the gas outlets  37  are arranged in a regular array around the longitudinal axis of the diffuser body  16 . This can be seen in, for example, FIG.  7 . 
     It is preferred that the lenses  20  be annular with a central opening  25  adapted to pass over the welding tip  14 . The welding tip  14  has a threaded portion  15  which threadingly engages in the diffuser body  16 , in the normal manner. 
     To now refer to the embodiment of FIGS. 4-7, where like components use like reference numerals but with the addition of a prefix number  1 , there is shown a head  110  which has a nozzle  112 , a welding tip  114 , a diffuser body  116  and a gasket  118 , all of these being similar to their counterparts in the embodiment of FIGS. 1-3. Again, there are provided diffusing lenses  120 , although here there are four such lenses. The lenses may all be the same, or may be different. The first lens  121  may be of reduced porosity to the remaining lenses  123 . The remaining lenses  123  may be all different, or may be all the same. Again, spacers  122  are used to separate the lenses  120 . Furthermore, a circlip  124  is used to hold them in position. 
     Here, the gas channels  136  are arranged in a regular way around the longitudinal axis of diffuser body  116 , but are somewhat longitudinally and radially outwardly from a central inlet  134 . In this way, the gas flows from inlet  134 , through channels  136  and outlets  137 , and then through the outlet end  138  of diffuser body  116 . That flow is essentially axial. Therefore, there is a reduced tendency for there to be turbulent flow before the gas contacts the lenses  120 . By virtue of the nature of the lenses  120 , the gas flow becomes almost entirely axial and therefore non-turbulent. As such, it will pass along the welding rod to the welding site. Therefore, there will be less tendency to entrap air and the efficiency of welding will be increased. By virtue of the more concentrated form of gas flow, and the higher pressure behind the gas flow due to the buildup in pressure caused by the lenses  120  the tendency of the gas flow to be displaced due to air flow will be significantly reduced. Efficiencies in accordance with the embodiments of FIGS. 1-3 have again been realised with this embodiment. 
     In trials it has been found that splatter and the like may be reduced. The splatter may cause damage to lenses  20 ,  120  but they can easily be replaced after removing circlip  24 ,  124 . A notch  41 ,  141  at outlet end  38 ,  138  is provided to assist in removing the circlip  24   124 . More than one notch  41 ,  141  may be provided. Further, due to the reduced air in the gas flow, the colour of the weld (particularly with stainless steel) may be noticeably improved. 
     It will be understood that the invention disclosed and defined herein extends to all alternative combinations of two or more of the individual features mentioned or evident from the text or drawings. All of these different combinations constitute various alternative aspects of the invention. 
     It will also be understood that the term “comprises” (or its grammatical variants) as used in this specification is equivalent to the term “includes” and should not be taken as excluding the presence of other elements or features.