Abstract:
An arc torch assembly or sub assembly having improved replacement and centering characteristics, where certain components of the torch head have particular characteristics which improve the operation, use and replaceability of the various components. Other embodiments utilize a thread connection which employs multiple separate and distinct thread paths to secure the threaded connections.

Description:
TECHNICAL FIELD 
       [0001]    Devices, systems, and methods consistent with the invention relate to cutting, and more specifically to devices, systems and methods for aligning and securing components of a liquid cooled plasma arc torch. 
       BACKGROUND 
       [0002]    In many cutting operations, plasma arc torches are utilized. These torches operate at very high temperatures which can damage many components of the torches. As such, some torches use liquid cooling to transfer the heat away from some of the cutting torch components. The cooling liquid is passed through various fluid chambers, etc. However, the presence and need for these chambers and passages means that alignment of some of the components of the torch assembly can be difficult, especially when components are replaced. When installation alignment is poor the performance of the cooling can be adversely affected and thus the usable life of the torch and torch components can be greatly diminished. Some torches have added various stabilizing portions on some of the components that extend into the cooling fluid paths, however these stabilizing portions can interfere with fluid flow and thus compromise the cooling abilities of the torch assembly. 
         [0003]    Further limitations and disadvantages of conventional, traditional, and proposed approaches will become apparent to one of skill in the art, through comparison of such approaches with embodiments of the present invention as set forth in the remainder of the present application with reference to the drawings. 
       BRIEF SUMMARY OF THE INVENTION 
       [0004]    An exemplary embodiment of the present invention is an arc torch assembly or sub assembly having improved replacement and centering characteristics, where certain components of the torch head have particular characteristics which improve the operation, use and replaceability of the various components. Other embodiments utilize a thread connection which employs multiple separate and distinct thread paths to secure the threaded connections. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]    The above and/or other aspects of the invention will be more apparent by describing in detail exemplary embodiments of the invention with reference to the accompanying drawings, in which: 
           [0006]      FIG. 1  illustrates an exemplary embodiment of a cutting torch coolant tube assembly of the present invention; 
           [0007]      FIG. 2  illustrates an another view of the cutting torch coolant tube of  FIG. 1 ; 
           [0008]      FIGS. 2A and 2B  illustrate a similar view of that shown in  FIG. 2 , but of a different exemplary embodiment; 
           [0009]      FIG. 3  illustrates an exemplary embodiment of an thread pattern that can be used with various components of the present invention; and 
           [0010]      FIG. 4  illustrates an exemplary embodiment of a torch assembly utilizing the assembly of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0011]    Exemplary embodiments of the invention will now be described below by reference to the attached Figures. The described exemplary embodiments are intended to assist the understanding of the invention, and are not intended to limit the scope of the invention in any way. Like reference numerals refer to like elements throughout. 
         [0012]      FIG. 1  depicts a diagrammatical representation of an exemplary embodiment of a cutting torch cooling tube electrode assembly  100  of the present invention. As is generally understood, the assembly  100  is inserted into a torch body which is not shown here for clarity (see  FIG. 4 ). The assembly  100  comprises a coolant tube  101  which is inserted into a channel  109  of a coolant tube holder  105  and a channel  104  of an electrode  107 . The distal end of the coolant tube holder  105  has an opening into which the electrode  107  is inserted. The proximate end of the holder  105  also has an opening into which the coolant tube  101  is inserted, as shown. 
         [0013]    The coolant tube  101  has a proximate end opening  103  which feeds into a channel  102  in the coolant tube. During operation, the cooling liquid is directed to the opening  103  and down through the channel  102  towards the distal end of the coolant tube  101 . The tube  101  has a length such that its distal end creates a gap  111  between the end of the tube  101  and an inner wall of the channel  104  of the electrode  107 . This gap  111  is important to the operation of the assembly  100  as the coolant flows down the channel  102  it passes through this gap  111  and enters the channel  104  of the electrode  107  and then the channel of the holder  105  to provide the desired cooling. Maintaining a consistent width of the gap  111  is important to proper coolant flow and in many known torch assemblies this is difficult to do, particularly when the electrode and/or coolant tube of prior torches is replaced. Because of the structure of known torches it is difficult to assemble the components to achieve the desired gap  111  dimension when replacing any of the components. This results in diminished cooling performance. Embodiments of the present provide for very consistent insertion of the tube  101  and the gap  111  dimension, as well as centering of the tube  101  in the channels  109  and  104 , which will be described in more detail below. 
         [0014]    Once the coolant passes through the gap  111  it is directed through the channel  109  towards the proximate end of the holder  105  between the outer surface  110  of the tube  101  and the inner surface  108  of the holder  105 . In embodiments of the present invention, the holder  105  contains a plurality of exit ports  106  which allows the coolant to exit the channel  109  and transfer heat away from assembly  100 . The ports  106  are positioned radially around a centerline of the holder  105  so that the coolant exits radially away from the holder  105  centerline as opposed to out of its proximate end. In exemplary embodiments, the holder  105  contains between 3 and 8 ports. The radial displacement of the ports is symmetrical to ensure even flow. The diameter of the ports is to be selected to ensure that the desired coolant flow is achieved during operation. In some exemplary embodiments all of the ports  106  have the same diameter. However, in other exemplary embodiments, the ports  106  can have different diameters. For example, half of the ports  106  can have a first diameter, while the other half of the ports  106  can have a second diameter which is less than the first diameter. Once the coolant exits the ports  106  it is recycled through a heat exchange and/or cooling system as is generally known and understood. Further, in some exemplary embodiments the ports have a circular opening, while in other exemplary embodiments, at least some of the ports  106  can have non-circular shapes like slots, etc. After cooling the electrode the coolant recirculates through the ports to a heat exchanger (not shown for clarity). 
         [0015]      FIG. 2  shows a close up view of the proximate end of the coolant tube holder  105  and the coolant tube  101 , which shows how the coolant tube  101  is stabilized and centered in the coolant tube holder  105 . As shown, the coolant tube  101  has a stabilization portion  123  which extends radially around the tube  101 . The stabilization portion  123  has an outer land surface  123 A which engages with the inner surface  108  of the holder  105 . When the tube  101  and the holder  105  are engaged with each other there is a friction fit engagement between the portion  123  and the surface  108 . The friction fit engagement between the portion  123  and the surface  108  holds the tube  101  centered in the channel  109  and ensures that each time the cooling tube, and other components are replaced the components are repositioned in a centered state with little difficulty. In exemplary embodiments, the portion  123  is configured such that the friction fit engagement with the holder  105  is continuous radially around the surface  108 . Stated differently, the engagement between the portion  123  and surface  108  is such that not fluid (cooling fluid, etc.) can pass between the portion  123  and the surface  108 . Thus, it is easier to replace the components, including the assembly  100  in a torch and providing more consistent accurate replacement. 
         [0016]    Another exemplary embodiment of the present invention, is shown in  FIGS. 2A and 2B , where the coolant tube  101  has extension portions  140  which extend radially outward from the portion  123  as shown. These extension portions  140  extend out from portion  123  into grooves  108 A in the coolant tube holder  105  and aide to ensure proper insertion into the coolant tube holder  105 . In exemplary embodiments the extension portions  140  have a friction fit with the grooves  108 A. This engagement aids in centering the coolant tube  101  as well as ensuring that the coolant tube  101  is oriented radially in the proper position. In exemplary embodiments, the extension portions  140  have a length which is less than the length L of the portion  123 . Further, the extension portions have a surface  141  which engages with an adjacent surface  141 A on the coolant tube holder  105 . The engagement of these two surfaces acts to again ensure proper placement of the coolant tube  101  in the coolant tube holder  105  and ensure that it is not inserted too far into the holder  105 . Although four portions  140  are shown in  FIGS. 2A and 2B , other embodiments can use a different number of portions  140 . 
         [0017]    In lieu of various aspects of the above described invention, the coolant tube  101  will always be inserted in a concentric state in its holder  105 . Thus preventing improper insertion and decreased component life. 
         [0018]    Additionally, as shown the tube  101  has securing portion  119 , which is closer to the proximal end of the tube than the stabilization portion  123 , which is used in conjunction with a third portion  119 A to hold an o-ring  130  in place. The o-ring  130  is used to provide a seal for the assembly  100  and tube  101  when installed in a torch assembly. Each of the securing portion  119  and the third portion  119 A extended radially around the tube  101 . The securing portion  119  has a distal surface  122  which, when installed in the holder  105 , engages with a the proximal end surface  120  of the holder  105 . Because of this engagement, the insertion of the tube  101  into the holder  105  will always be made at the appropriate position to ensure that the gap  111  is the proper distance. In known torch assemblies the depth of insertion is difficult to repeat or perform consistently. Thus, the surfaces  122  and  120  ensure that the tube  101  is inserted to the proper distance easily and nearly eliminates error during replacement and assembly. Further, the combination of having the surface  122  engage with the surface  120  at the proximal end of holder  105  and the portion  123  engaging with the surface  108  provides a coolant tube assembly  100  with improved centricity and improved reliability during assembly and replacement of components over known torches. The combination of these engagements in close proximity to each other ensures that the tube  101  is inserted into the holder  105  at the proper depth for the gap  111  and centered within the channel  109 . Further, this configuration allows the tube  101  to be configured without positional protrusions closer to the distal end of the tube  101 . In some known torch assemblies the coolant tube has protrusions positioned closer to the distal end of the tube to aid in centering the tube. However, these protrusions extend into the coolant flow path and thus impede coolant flow and coolant performance. Some exemplary embodiments of the present invention can use positional protrusions, but because of the advantages of the above discussed configuration the protrusions can be smaller, and in many applications are not necessary. 
         [0019]    Also as shown in  FIG. 2 , exemplary embodiments of the present invention include an undercut portion  133  positioned between portions  119  and  123 . This undercut portion serves to ensure proper seating between surfaces  122  and  120  and thus the coolant tube  101  in the coolant tube holder  105 . This undercut portion  133  is to have a length along the coolant tube which is less than the length L of the portion  123 . 
         [0020]    As described above, the stabilization portion  123  aids in stabilizing the tube  101  when inserted into the holder  105  in a press fit state. Thus, the length of the portion  123  needs to be sufficient to provide the desired stabilization and ensure centricity when inserted. To achieve this, in exemplary embodiments of the present invention, the outermost plateau surface  123 A of the portion  123  has a length L that is in the range of 10 to 20% of the length of the tube  101  which is inserted into the holder  105  (the length of the tube from its distal end at the gap  111 ). Having a plateau length in this range ensures sufficient alignment and stability while also allowing for accurate and repeatable positioning. In other exemplary embodiments the length of the plateau portion  123 A is in the range of 4 to 25% of the length of the tube  101  within the holder  105 . The plateau length L described above is the length of the flat surface on the portion  123  that makes contact with the inner surface of the holder  105  when the tube is inserted into the holder  105 . 
         [0021]    As also shown in  FIG. 2 , the portion  123  has an angled surface  123 B which extends from the body of the tube  101  to the plateau surface  123 A. The angled surface  123 B aids in guiding the flow of the coolant fluid out of the ports  106 . This aids in preventing the creation of stagnation zones in the fluid flow and increases the performance of the fluid flow. In some exemplary embodiments, the angle A between the body of the tube  101  and the surface  123 B is in the range of 16 to 60 degrees. In other exemplary embodiments the angle is in the range of 40 to 60 degrees. Further, as shown in  FIG. 2 , the center of the angle A is positioned such that it aligns with the centerline of the ports  106 . If the angle A is a radiused angle A, as in some exemplary embodiments, then the center A corresponds to the center of a circle defined by the radius of the angle A, whereas if the angle A is a sharp angle then the center of the angle A is the inflection point. In some exemplary embodiments, the center of the angle A is aligned with the centerline of the ports  106 . In other exemplary embodiments, the centerline of the angle A is positioned such that it is close to the centerline of the ports  106 , but does not have to be aligned with the centerline. In such embodiments, the center of the angle A is positioned within 10% of the diameter of the ports  106  with respect to the centerline of the ports  106 . For example, if the diameter of the ports  106  is 0.25″, the center of the angle A is aligned within +/−0.025″ of the centerline of the ports. If the ports have varying diameters (as referenced previously) the average of the port diameters is to be used to determine the range of alignment as described above. 
         [0022]    As shown in  FIG. 1 , the electrode  107  is shorter and threaded into the coolant tube assembly. Such a configuration allows the electrode  107  to be considerably smaller and much easier to be replaced. Because of this configuration, in exemplary embodiments of the present invention, the electrode  107  can have a length (form its most distal to most proximate ends) that is within the range of 4 to 20% of the coolant tube assembly  100 , 5 to 20% of the length of the coolant tube  101 , and within the range of 5 to 20% the length of the coolant tube holder  105 . With these ratios, embodiments of the present invention provide excellent cutting performance and at the same time allow for ease of replacement and alignment of each of the respective components, as described herein. That is, when a component such as the electrode  107  need be replaced, the fit and construction of the assembly of the holder  105  and tube  101  (which can be replaced as a single unit) ensures proper replacement. Further, it is not necessary to remove the coolant tube holder and thus risk misaligning the coolant tube holder or the remainder of the assembly  100  when replacement of the electrode  105  is needed. Additionally, the coolant tube holder  105  and the coolant tube  101  can be kept as an assembly to be replaced as needed which ensures that the assembly 
         [0023]    The electrode  107  can be made of known materials used for electrodes, including but not limited to copper, silver, etc. Further, because of the reduced size of the electrode  107  there is a significant reduction in cost by just replacing the electrode  107  of the present invention. 
         [0024]      FIG. 3  depicts another aspect of the present invention, which aids in ensuring proper alignment and centricity during assembly and replacement of components of the assembly  100 . Specifically,  FIG. 3  depicts a quick-coupling, multi-start thread configuration which is used on various components of the torch assembly  100 , and can be used on other components of a torch. As described more fully below, the thread design employs multiple starts and a modified thread pitch to enhance alignment and installation, during assembly and replacement. 
         [0025]    As described previously, it is often necessary to remove and replace worn components of a cutting torch. Because of the need to replace components often it is desirable to speed up the process while at the same time ensuring that the replaced components are properly installed and aligned. Known torch assemblies use a standard single thread design, and some have used a bayonet thread design. However, these thread designs often require an appreciable number of turns to complete the installation, and increase the likelihood of an error during threading, such as cross-threading. For example, in most applications replacement of threaded components can require anywhere from 5 to 10 full turns of the item. By having such large number of turns for a component there is an increased likelihood of cross-threading the component, and/or result in the component not being completely tightened which can result in leaks and/or poor component life. Embodiments of the present invention address these issues by using a multi-thread design which utilizes existing required installation torque and thread stresses while maintaining the same applied force to mating parts as known thread systems. 
         [0026]      FIG. 3  depicts an exemplary embodiment of an electrode  300  having a multi-thread design of the present invention. Specifically, the electrode  300  has a thread portion  301  having a plurality of separate and distinct thread paths  303 A,  303 B and  303 C. The embodiment shown has three distinct thread paths  303 , but other embodiments of the present invention can use more than three thread paths. For example, other exemplary embodiments can use 4 distinct thread paths, and others can use as many as 5 different thread paths. By using multiple thread paths, embodiments of the present invention can provide easy and accurate replacement of components, greatly minimizing misalignment and/or cross-threading of components, while at the same time providing the required and desired applied connection force. Embodiments of the present invention, also deliver the desired mating force by using significantly less complete rotations of the component, thus making the replacement of a component quicker and more consistent. For example, embodiments of the present invention can provide the complete installation of a component with only 1 to 2 complete rotations of a component. In some exemplary embodiments, complete installation of a component can be achieved by 1.25 to 1.5 complete rotations of the component. For example, in certain applications electrodes of the present invention can be installed with only 1.25 to 1.5 complete rotations. By using such a low number of rotations to complete an installation, the chances of accurate and complete installation are greatly increased 
         [0027]    Thus, embodiments of the present invention can provide highly accurate installation by ensuring proper alignment, minimizing the chances of cross threading or misalignment and ensuring that the component (for example the electrode  107 ) is fully installed. By reducing the number of rotations required to install a component, embodiments of the present invention make it much easier on an installer to ensure that complete installation has been achieved. Because of the advantages of the present invention, the multi-thread configuration can be used on all components of a torch head assembly that utilize threads, and in particular those threads on components that are frequently replaced. For example, each of the threads  115 ,  117  and  127  shown in  FIG. 1  can have the multi-thread configuration as described above. Further, in addition to these components, embodiments can also use this thread configuration on other torch assembly components, such as quick disconnect rings, inner and outer retaining caps, electrodes, coolant tubes, holders, etc. As shown in  FIG. 4 , the torch attachment ring  401  connects the torch head to the torch base, the outer retaining cap  403  aids in retaining the torch shield cap and the inner retaining cap  405  aids in retaining the torch nozzle. 
         [0028]      FIG. 4  depicts an exemplary embodiment of a torch assembly  400  that contains the assembly  100  from  FIG. 1 . Because the other components of the torch assembly  400  are generally known, they are not discussed in detail herein. Of course, various embodiments of the present invention are not limited to the configuration of the torch assembly  400  as shown in  FIG. 4 , or the assembly  100  as shown in  FIGS. 1 and 2 , and these embodiments are intended to be exemplary. 
         [0029]    While the claimed subject matter of the present application has been described with reference to certain embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the claimed subject matter. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the claimed subject matter without departing from its scope. Therefore, it is intended that the claimed subject matter not be limited to the particular embodiment disclosed, but that the claimed subject matter will include all embodiments falling within the scope of the appended claims.