Abstract:
A torch for use in welding operations during which smoke and/or fumes are created has a nozzle and a handle connected to a conduit extending between the handle and the nozzle. A fume extraction duct extends from the nozzle and through the handle. An annular member surrounds the axial end of the nozzle and has a plurality of openings oriented such that fumes and ambient air are extracted in a direction substantially parallel to the longitudinal axis of the nozzle. A switch is provided to control fume extraction between a full flow rate and a partial flow rate.

Description:
BACKGROUND 
   During welding or cutting, especially of metallic parts, gases and solid material are generated which not only tend to obstruct the operators vision, but also tend to cause visual and respiratory discomfort. This is especially true when welding or cutting in confined areas, such as assembly lines in factories, where several such operations may be in progress simultaneously. 
   One difficulty encountered in existing fume extracting torches is in the size and weight of the torch employing such a fume extracting device, and the fact that a large nozzle will interfere with the operator&#39;s view. An example of a previous attempt to incorporate a fume extracting device with a hand held welding torch is found in U.S. Pat. No. 3,980,860 which is hereby incorporated by reference. 
   Another difficulty is in the fact that the fume extracting passageways of existing devices get very hot due to the heat of the fumes drawn away from the weld. This heat causes the fume carrying conduits to deteriorate, and if these conduits are carried by the gun, then the gun handle becomes hot and uncomfortable to handle. If the fume extracting conduit is not carried in the handle, then the torch and associated cables and conduits become unwieldy and cumbersome. Another difficulty, especially where the torch is a welding gun, is in the interference of the fume extracting nozzle with any shielding gas which might be used. 
   Another problem with existing fume extracting nozzles is that the nozzles are not efficient at extracting ambient air and fumes from the work surface. The openings are not oriented and arranged so that a maximum amount of ambient air and fumes are extracted. 
   Thus, it is desirable to provide a fume extracting device in combination with a welding torch handle which has a more efficient method of extracting fumes and ambient air from a work surface. 
   SUMMARY OF THE INVENTION 
   In accordance with one aspect of the present invention, this invention relates to an improved hand held torch for welding or cutting including a nozzle designed to remove smoke and fumes in which a fume extracting conduit is carried within the torch handle. 
   Specifically, according to one aspect of the invention, a fume extracting conduit is formed as an integral part of the torch handle, and this conduit, along with the smoke and fumes carried thereby, are cooled sufficiently to prevent rapid deterioration of the conduit and heating of the handle to the extent that it will become uncomfortable to the operator. In the preferred embodiment of the invention, cooling of the conduit and fumes include mixing sufficient ambient air with the welding fumes. This ambient air, in combination with the positioning of the smoke and fume extracting orifice on the nozzle but away from the area of the weld or cutting operation allows the temperature of the handle to be maintained within acceptable limits. 
   In the embodiment of the invention, the torch handle and associated cables can be made of smaller and lighter material than used in prior art devices, and have a long life since the temperature of these materials is maintained within the handle. An easy to manipulate, hand held torch is provided. 
   Thus, in accordance with another aspect of the invention, a torch for use in welding operations during which smoke and/or fumes are created includes a nozzle which has a longitudinal axis and an axial end adjacent which welding occurs. The nozzle has a wire electrode, terminating in an arc tip. A handle is connected to a conduit extending between the handle and the nozzle and through the handle. A fume extraction duct extends from the nozzle and through the handle. An annular member surrounds the axial end of the nozzle. The annular member has at least one opening oriented such that fumes and ambient air are extracted in a direction substantially parallel to the longitudinal axis of the nozzle. 
   In accordance with another aspect of the invention, a nozzle for a welding torch used during welding operation during which smoke and/or fumes are created has an opening through which welding wire is inserted. A fume extraction duct extends through the nozzle adjacent the opening. An annular ring surrounds an axial end of the nozzle. The annular ring has a plurality of openings, wherein the openings are oriented such that fumes and ambient air are extracted in a direction substantially parallel to the longitudinal axis of the nozzle. 
   In accordance with another aspect of the invention, a nozzle for a welding torch used during a welding operation during which smoke and/or fumes are created has a switch which controls fume extraction flow between a full flow rate and a partial flow rate by activating a valve. 
   Accordingly, it is an aspect of this invention to provide an improved hand held torch in which a smoke and fume extracting nozzle is employed to draw fumes from the area of a welding or cutting operation and in which a fume carrying conduit is formed as an integral part of the torch handle; and to provide an improved torch of the type described wherein the handle of the torch is cooled so that the heat from the welding or cutting operation will not deteriorate the materials used in the gun and will not cause discomfort to the operator. 
   Another aspect of the invention is to provide a nozzle for the welding torch which efficiently draws ambient air and fumes into the nozzle and cools the fumes. 
   Other aspects of the invention will become apparent to those skilled in the art upon a reading and understanding of the following detailed description. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a schematic view of a welding torch, and fume gun assembly connected to a vacuum source in accordance with a preferred embodiment of the present invention; 
       FIG. 2  is an elevational view, partly in cross section, of one embodiment of the invention wherein ambient air is mixed with the fumes drawn in by a welding torch nozzle to cause cooling thereof; 
       FIG. 3  is an enlarged view taken in partial cross-section, of a welding gun nozzle shown in  FIG. 2 ; 
       FIG. 4  is a cross sectional view taken along line  4 - 4  of  FIG. 3 ; 
       FIG. 5  is a bottom plan view of the nozzle of  FIG. 4 ; and 
       FIG. 6  is schematic view of a welding torch and fume gun assembly welding power supply and fume extracting pump assembly. 
   

   DETAILED DESCRIPTION 
   Reference is now made to the drawings which show the preferred embodiments of the invention, and particularly to  FIG. 1  which is a schematic view of a welding system in accordance with a preferred embodiment of the present invention. While the invention will be described herein with reference to gas shielded welding guns or torches, it is to be understood that this invention can also apply to MIG and TIG welding torches as well as to cutting torches. 
   Referring to  FIG. 1 , a welding torch  10  is shown in position above a workpiece  12  which is typically connected by means of a ground wire to a welding power supply (not shown). The welding torch  10  is typically supplied with wire  16  from a wire supply reel via a control system  17 . The control system not only regulates the rate at which welding wire  16  moves into the torch, but it can also regulate the flow of shielding gas from a gas source. 
   The welding torch  10  includes a nozzle  14  having a fume extracting orifice connected to a passageway carried through a torch handle  18  and supply cable  20  to a vacuum pump  22  ( FIG. 6 ). A switch  24  in the handle of the torch is also connected by wires running through the cable  20  to the control system  17 . Referring now to  FIG. 6 , the switch  24  is used to control the amount of fumes and ambient air extraction between a full and a partial flow. The vacuum pump  22 , operated by a motor assembly  23 , draws the ambient air and fumes through the system. 
   When the switch  24  is in the off position, as shown in  FIG. 6 , a valve assembly  25 , such as a solenoid valve, is positioned so that an opening  27  in the valve is aligned with opening  29  in tube or conduit  31 . Opening  27  allows a full flow of fumes and ambient air through the system. If a reduced flow rate is desired, the switch is depressed to an on position, which moves the valve  25  to a lower position, aligning smaller opening  33  of the valve with opening  29  of tube  31 . 
   Opening  33  has a first end  35  and a second end  37 , wherein the first end has a larger diameter than the second end, which has a diameter approximately half of the diameter of the first end. Thus, the flow rate is essentially reduced by half through the system. 
   The handle  18  of the torch is of relatively small size, and since only a single cable  20  is used which carries all of the necessary cooling, control, power supply, and wire feeding conduits, a welding system is thereby provided which is convenient and easy to use and not unwieldy or cumbersome. 
   Referring now to  FIG. 2  which illustrates the preferred embodiment of the invention, the welding torch  10  includes an inner conduit  28  through which shielding gas and welding wire are supplied. This conduit may also carry electrical control wires to handle mounted switch  24 . The handle also carries a fume conduit  30  through which the fumes removed from the area of the weld are directed as they are drawn through the handle by the vacuum pump  22 . Both the inner conduit  28  and the fume conduit  30  are surrounded by an outer casing  32 . 
   The nozzle  14 , shown in detail in  FIG. 2 , includes a contact tip  34  having formed therein a passageway  36  through which welding wire  16  is directed into the weld. At an upper end  38  of the contact tip the passageway opens up so that it has substantially the same diameter as the passageway  39  in wire guide tube  40 . The contact tip  34  supplies substantially all of the electrical energy to the wire so that there will be practically no resistance heating of the welding wire  16  prior to its exiting the lower end of the contact tip. 
   The contact tip is received into and extends through a tapered opening  44  formed in a tip holder  46 . The contact tip can also be tapered, and the outer surface of the contact tip and the opening  44  form an electrical contact so that electric current flowing through the inner conduit  28  will be carried to the welding wire. The tip holder  46  can include an internal thread which cooperates with an external thread on the wire guide tube  40  to cause the contact tip to firmly and positively engage the end of this tube. Between the end of the wire tube and the contact tip is formed a manifold  48  into which shielding gas from passageway  42  may flow and then be directed through a plurality of passageways  42  into a chamber  50  where the shielding gas is then directed over the weld. The chamber  50  is formed between the contact tip  34  and an insulating cylinder  52 . 
   Outer shell  60  of the nozzle together with the outer cylindrical portion of the insulating cylinder  52  form a fume extracting passageway or chamber  62  into which the fumes generated by the weld may be drawn into the nozzle from the work surface in the direction shown by the arrows  64 . This fume passageway extends upwardly into a passageway  66  in the gun formed between the guide tube  40  and exhaust jacket or outer casing  32 . A plurality of orifices or openings  70  are formed between the lower end of the outer shell  60  and the cylinder  52  to extract ambient air and fumes from the work surface into the nozzle. 
   The fume chamber  62  is connected to the fume conduit or passageway  66  by means of an opening  72  located near an upper end  73  of the nozzle. As may be seen in  FIG. 2 , the wire guide tube  40  and outer casing  32  bends downwardly in a goose-neck shaped configuration from the handle  18 . The opening  72  is located near this bend, and therefore the entrance to the fume conduit  66  is substantially axially aligned with the passageway  62 . This will result in a substantially equal pressure existing completely round the circumferential extent of the openings  70  and will allow fumes to be drawn into the nozzle evenly from any location around the nozzle. 
   In the embodiment of the invention shown in  FIG. 2 , the size of the openings  70 , the passageways  62  and  66 , and the fume conduit  30  are so designed that, in combination with the capacity of the vacuum pump  22 , sufficient ambient air is drawn into and mixed with the hot fumes removed from the welding area that the torch handle  18  is maintained at a temperature below that which would cause rapid deterioration of the gun materials or discomfort to the operator. Also, the openings  70  are so located axially on the nozzle that the fumes must travel upwardly and away from the weld and are therefore cooled somewhat prior to entering the openings  70 . This combination therefore allows a welding gun to be constructed of a size which is convenient to use, since only one cable is attached thereto, and which provides for the efficient removal of smoke and fumes from the area of the weld. 
   As seen in  FIGS. 3 and 5 , in accordance with the preferred embodiment of the present invention, a plurality of spaced apart openings or orifices  70  are formed along the circumference of an annular ring  80  formed on outer shell  60 . The ring  80  is formed by a portion of the nozzle which has a larger diameter and has rounded edges as compared to the diameter of the remaining portion  81  of the nozzle. The openings are shown to be circular; however, other shapes could be used without departing from the scope of the invention. The openings are shown to be equally spaced apart; however, other configurations could be used without departing from the scope of the present invention. 
   Referring to  FIG. 2 , the openings or apertures  70  are configured such that the ambient air is mixed with fumes from the welding procedure to be drawn into the fume chamber in a direction substantially parallel to a longitudinal axis  83  of the welding torch as shown by arrows  64 . By orienting the openings this way, the air is drawn directly into the torch, thus increasing the efficiency with which the ambient air is used to cool the extracted fumes and the handle. The plurality of openings are shown to be closely spaced together to increase the amount of air and fumes that are extracted from the work area into the welding torch and fume gun. 
   Referring now to  FIG. 4 , the nozzle portion has a plurality of tabs  84  formed on an inner diameter  85  of nozzle portion  81  for interlocking the nozzle section onto mating slots  86  an end of the welding torch conduit or passageway  66 . The nozzle tabs engage the slots and the nozzle can be rotated to easily lock and unlock the nozzle onto the end of casing  32 . 
   The exemplary embodiment has been described with reference to the preferred embodiments. Obviously, modifications and alterations will occur to others upon reading and understanding the preceding detailed description. It is intended that the exemplary embodiment be construed as including all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.