Abstract:
A method and apparatus for indicating a temperature of a torch consumable is disclosed. The invention includes a shielding cup constructed to be attached to a torch having a coating which indicates a temperature of the shielding cup during a welding/cutting process. Preferably, the coating indicates to a user when the temperature of the torch is beyond a preferred operating range thereby preventing excessive wear of the consumables associated with overheating.

Description:
BACKGROUND OF INVENTION  
       [0001]     The present invention relates generally to plasma cutting systems and other high power output welding-type systems such as welding and induction heating systems and, more particularly, to a temperature indicating consumable for use with such systems.  
         [0002]     Plasma cutting is a process in which an electric arc is used to cut a workpiece. Plasma cutters typically include a power source, an air supply, and a torch. The torch, or plasma torch, is used to create and maintain the plasma arc that performs the cutting. A plasma cutting power source receives an input voltage from a transmission power line or generator and provides an output voltage to a pair of output terminals, one of which is connected to an electrode and the other of which is connected to the workpiece.  
         [0003]     An air supply is used with most plasma cutters to help start the arc, provide the plasma gas to the torch, and cool the torch. A movable or fixed electrode or consumable serves as a cathode and a fixed nozzle serves as an anode. The air supply moves the electrode and as the electrode moves away from the nozzle, it opens the nozzle, and a plasma jet is created. The plasma jet causes the arc to transfer to the work piece, and thus initiates the cutting process. In other plasma cutting systems, a high frequency starter is used to initiate the cutting process.  
         [0004]     During the cutting process, as the arc transfers on the plasma from the electrode to the workpiece, heat is generated. The amount of heat generated during operation is partially determined by the type of material being worked, the power output required to work the material, and the type of consumable required to effectuate the desired work. Operating the torch at increased temperatures can effectively shorten the working life of a consumable, and if not addressed, can result in damage to the torch body and/or the power source. Additionally, plasma cutting with an overheated consumable also results in poor cut quality.  
         [0005]     It would therefore be desirable to design a consumable which indicates an operating temperature of the consumable.  
       SUMMARY OF INVENTION  
       [0006]     The present invention is directed to a method and apparatus for indicating the temperature of consumables over-coming the aforementioned drawbacks.  
         [0007]     A method and apparatus for indicating the temperature of a torch consumable is disclosed. The invention includes a shielding cup constructed to be attached to a plasma torch and constructed to indicate a temperature of the shielding cup during some phase of a welding/cutting process. The coating indicates to a user when the temperature of the consumable is beyond a preferred operating range, thereby preventing excessive wear of the consumables.  
         [0008]     Therefore, in accordance with one aspect of the present invention, a shielding cup is disclosed having a body with an outer surface, a first end connectable to a torch, and a second end connectable to a shield. A thermally responsive coating is formed on the shielding cup and provides an indication of the temperature of the shielding cup. As such, an operator is informed that the temperature of the consumable assembly has reached a maximum operating temperature. Such a construction allows an operator to suspend operation prior to thermal damage to the consumables.  
         [0009]     In accordance with another aspect of the present invention, a plasma cutter is disclosed that includes a power source configured to condition power into a form usable for a plasma cutting process. A torch is connected to the power source and configured to effectuate the plasma cutting process and includes a shielding cup and a temperature indicator connected thereto. The temperature indicator is configured to indicate a temperature of the shielding cup so that a user can suspend the cutting process before overheating occurs.  
         [0010]     According to another aspect of the present invention, a plasma torch consumable kit is disclosed that includes an electrode, a tip, and a shielding cup constructed to provide a temperature indication. Such a kit allows a user to replace a similar consumable with a consumable assembly that includes a temperature indicator.  
         [0011]     In accordance with a further aspect of the present invention, a method of manufacturing a plasma torch consumable is disclosed that includes the steps of providing a shielding cup having a body and forming the shielding cup to indicate temperature. Such a construction allows a user to readily observe the point at which the shielding cup has reached a maximum operating temperature.  
         [0012]     Various other features, objects and advantages of the present invention will be made apparent from the following detailed description and the drawings. 
     
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0013]     The drawings illustrate one preferred embodiment presently contemplated for carrying out the invention.  
         [0014]     In the drawings:  
         [0015]      FIG. 1  is a perspective view of one plasma cutting system incorporating the present invention.  
         [0016]      FIG. 2  is a cross-sectional view of a plasma torch consumable constructed in accordance with the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0017]     The present invention is directed to a temperature indicating consumable. As will be described below, the present invention is directed to a plasma torch consumable set that indicates a temperature to an operator. The temperature that is indicated to the operator is indicative of excessive temperature and is consumable set specific. That is, in a preferred embodiment, one consumable set will operate at one temperature and another consumable set may be constructed to operate at, and indicate, another temperature. One skilled in the art will readily appreciate that indicating an operating temperature of a consumable will be equivalently applicable to other high power output systems such as welding systems and induction heating systems.  
         [0018]     Referring to  FIG. 1 , a plasma cutting system  10  is shown. The plasma cutting system is a high voltage system with maximum open circuit output voltages ranging from approximately 230 Volts Direct Current (VDC) to over 300 VDC. The plasma cutting system  10  includes a power source  12  to condition raw power and regulate/control the cutting process. Specifically, the power source  12  includes a processor that, as will be described, receives operational feedback and controls the plasma cutting system  10  accordingly. Power source  12  includes a lifting means, such as a handle  14  which effectuates transportation from one site to another. Connected to the power source  12  is a torch  16  via cable  18 . The cable  18  provides the torch  16  with power and serves as a communications link between the torch  16  and power source  12 .  
         [0019]     Also connected to power source  12  is a work clamp  20  which is designed to hold a workpiece (not shown) to be cut and provide a grounding path. Connecting work clamp  20  to the power source  12  is a cable  22  designed to provide a return path for the cutting current from the torch through the workpiece and the work clamp  20 . Extending from a rear portion of power source  12  is power cable  24  having plug  26  for connecting the power source  12  to a portable power supply  28  or a transmission power receptacle (not shown). Power source  12  further includes an ON/OFF switch  30 .  
         [0020]     To effectuate cutting of a workpiece, torch  16  is placed in close proximity to a workpiece connected to clamp  20 . A user may then activate a trigger (not shown) on the torch  16  to deliver power to the torch  16  to initiate a pilot arc. Shortly thereafter, a cutting arc is generated and the user may then slowly move the torch across the workpiece to cut the workpiece. The user may adjust the torch speed to reduce spark splatter and provide a more-penetrating cut. Gas is supplied to torch  16  from a pressurized gas source  33  or from an internal air compressor.  
         [0021]     Referring now to  FIG. 2 , a cross-section of a plasma cutting torch  16  is shown. Plasma torch  16  is defined by a torch body  36  that is designed to receive a shielding cup  38 . Shielding cup  38  is connected to torch body  36  so as to define a gas chamber  40  that, as will be described in greater detail below, allows for the charging of the gas to a plasma and passage of the plasma therethrough. Centrally disposed within gas chamber  40  and connected to torch body  36  is electrode  42 . Electrode  42  is removably connected to torch body  36  and is specifically designed for a particular plasma cutting process. Collectively, electrode  42 , shielding cup  38 , and a tip  44  form a consumable set  47 . Torch  16  is constructed such that various consumable sets may be interchangeably connected depending upon the particular plasma cutting process to be carried out. Additionally, it is understood that electrode  42  and tip  44  can be worn, or consumed, at a greater pace than shielding cup  38  so that the shielding cup can be repeatedly used with replacement tips and electrodes before it would require replacement.  
         [0022]     Tip  44  is connected to shielding cup  38  and is constructed to form a nozzle  46 . In operation, gas is injected into chamber  40  via passages  48  and is superheated to a plasma state. An O-ring  49  forms a seal between shielding cup  38  and torch body  36  and prevents plasma from exiting chamber  40  therebetween. The plasma is forced out of the chamber through nozzle  46  and out of tip  44  via opening or aperture  50 . Nozzle  46  is designed to focus the velocity as well as the heat of an arc that is created between a workpiece (not shown) and electrode  42 . Electrode  42  is constructed such that the arc extends across an arc path  52  out of the consumable through opening  50 .  
         [0023]     Torch  16  also includes, preferably, an indicator band  54  formed about shielding cup  38  that is designed to indicate to a user the operating temperature of consumable set  47  connected to torch body  36 . The indicator band  54  is designed to glow or change colors in order to provide an operator with an indication that the consumable set has reached a predetermined temperature. The predetermined temperature, the indicated temperature, is the temperature at which further operation of consumable set  47  would result in overheating of consumable set  47 . Additionally, it is understood that in the event consumable set  47  is reconfigured to operate at a higher temperature, i.e. by inserting a different electrode or tip, indicator band  54  could also be changed so as to indicate a second operating temperature.  
         [0024]     It is equally understood and within the scope of the claims that shielding cup  38  include additional indicator bands such as a second indicator band  55  to indicate a second operating temperature. Such a construction would allow the shielding cup  38  of consumable set  47  to indicate multiple temperatures, such as a first and a second operating temperature. It is also equally understood and within the scope of the claims that indicator bands  54 ,  55  be configured to indicate temperature in any number of ways including, but not limited to, glowing, changing color, or emitting odor. Such indicators are only by way of example and are not intended to limit the scope of the claims included herein.  
         [0025]     Indicator band  54 , by being placed directly about shielding cup  38 , is closely located to an operator&#39;s focus point during operation of the torch. As such, when consumable set  47  reaches a maximum operating temperature, an operator is nearly instantaneously notified of such a condition and can stop the cutting process. Such a construction prevents overheating of the consumable set. Additionally, since cut quality is partially dependent on consumable quality, an operator can maximize the quality of a cut by stopping the cutting process prior to overheating of the consumable set.  
         [0026]     As one skilled in the art will fully appreciate, the heretofore description of welding devices not only includes plasma torches, but also includes any system that requires high power outputs, such as heating and cutting systems. Therefore, the present invention is equivalently applicable with any device requiring high power output, including welders, plasma cutters, induction heaters, and the like. Reference to welding power, welding-type power, or welders generally, includes welding, cutting, or heating power. Description of a welding apparatus illustrates just one embodiment in which the present invention may be implemented. The present invention is equivalently applicable with many high power systems, such as cutting and induction heating systems, or any similar systems.  
         [0027]     Therefore, in accordance with one embodiment of the present invention, a shielding cup has a body with an outer surface, a first end connectable to a torch, and a second end connectable to a shield. A thermally responsive coating is formed on the shielding cup and provides an indication of the temperature. As such, an operator is informed that the temperature of the consumable assembly has reached a maximum operating temperature. Such a construction allows an operator to suspend operation prior to thermal damage to the consumables.  
         [0028]     In accordance with another embodiment of the present invention, a plasma cutter includes a power source configured to condition power into a form usable for a plasma cutting process. A torch is connected to the power source and configured to effectuate the plasma cutting process and includes a shielding cup and a temperature indicator connected thereto. The temperature indicator is configured to indicate a temperature of the shielding cup so that a user can suspend the cutting process before overheating occurs.  
         [0029]     According to another embodiment of the present invention, a plasma torch consumable kit includes an electrode, a tip, and a shielding cup constructed to provide a temperature indication. Such a kit allows a user to replace a similar consumable with a consumable assembly that includes a temperature indicator.  
         [0030]     In accordance with a further embodiment of the present invention, a method of manufacturing a plasma torch consumable includes the steps of providing a shielding cup having a body and forming the shielding cup to indicate temperature. Such a construction allows a user to readily observe the point at which the shielding cup has reached a maximum operating temperature.  
         [0031]     The present invention has been described in terms of the preferred embodiment, and it is recognized that equivalents, alternatives, and modifications, aside from those expressly stated, are possible and within the scope of the appending claims.