Abstract:
A system and method for generating a weld are provided. A power circuit in communication with a control circuit generates welding output voltage. A voltage reducing circuit in communication with the power circuit generates a reduced output voltage relative to the welding output voltage if the system determines that the welding process is idle for the predefined period of time. The welding output voltage is restored from the reduced voltage if the welding process is restarted.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Patent Application No. 61/490,329 filed May 26, 2011, the content of which is hereby incorporated by reference in its entirety. 
    
    
     BACKGROUND 
     When a welding operation idles due to a user moving a welding gun away from a part to be welded, the idled welding gun may be a hazard to user. Existing voltage reducing devices have been used to reduce output voltage immediately after the end of the arc when the welding gun is moved away. Moreover, existing voltage reducing devices do not allow for finer control of output voltage during the idled phase. 
     SUMMARY 
     A system for generating a weld is provided. A power circuit generates welding output voltage for a welding process. A control circuit may be in communication with the power circuit. A voltage reducing circuit in communication with the power circuit generates a reduced output voltage relative to the welding output voltage if the process is idle for a period of time. 
     A method for generating a weld is also provided. The method includes generating, by a power circuit, a welding output voltage for a welding process. The method further includes generating, by a voltage reducing circuit, a reduced output voltage relative to the welding output voltage if the welding process is idle for a period of time. 
     In some implementations, the power circuit generates welding output voltage for a welding process. The control circuit may be in communication with the power circuit. Voltage and current feedback circuits may determine whether the welding process is idle for a predefined period of time and detect contact between the electrode and the part to be welded. The voltage reducing circuit in communication with the power circuit can generate a reduced output voltage relative to the welding output voltage if the feedback circuits determine that the welding process is idle for the predefined period of time. The welding output voltage is restored from the reduced voltage if the feedback circuits detect the contact or the trigger is pulled. 
     Further objects, features and advantages of this application will become readily apparent to persons skilled in the art after a review of the following description, with reference to the drawings and claims that are appended to and form a part of this specification. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
         FIG. 1  is a schematic view of a welding system; 
         FIG. 2 a    is a perspective view of a housing which contains the welding system of  FIG. 1 ; 
         FIG. 2 b    is a front view of an interface on the housing of  FIG. 2   a;    
         FIG. 3  is a schematic view of a circuit having a voltage reducing device; 
         FIG. 4  is a flow chart illustrating a method of energy conservation and improved cooling in arc welding machines; and 
         FIG. 5  is a schematic view of a processing system for implementing the methods described herein. 
     
    
    
     It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features. 
     DETAILED DESCRIPTION 
     The term “substantially” used herein with reference to a quantity or mathematical relationship includes (1) a variation in the recited quantity or relationship of an amount that is insubstantially different from a recited quantity or relationship for an intended purpose or function, or (2) a variation in the recited quantity or relationship of an amount that produces the same quality. 
     Now referring to  FIG. 1 , a power supply for a welding system  100  is provided. The power supply  110  receives input power  112  which may be an alternating current power line, for example a 220 volt AC power line. However, it is understood that the power supply  110  may be adaptable to receive a range of voltages, for example between 187 to 276 volts AC. In addition, it may also be possible to configure the power supply for other voltage ranges depending on the application and required welding output power. The power supply  110  provides a direct current power output voltage  114  that may be used as a welding output power  116 . In some implementations, the power supply  110  may be used for stick welding (also known as Shielded Metal Arc Welding or SMAW) or various other welding applications such as MIG (Metal Inert Gas, also known as gas metal arc welding or GMAW), flux core arc welding, TIG (tungsten inert gas welding, also known as Gas Tungsten Arc Welding or GTAW), plasma arc, or other welding processes. Therefore, in one example the current return lead of the welding output power  116  may be provided to a part  118  that is to be welded, and the supply voltage may be provided to an electrode, for example a stick  120  or wire  122 . Therefore, as the stick  120  comes in contact with the part  118  an arc may be formed that melts both the base metal and electrode and cooperates to form a weld. In other implementations, the output voltage may be provided through a wire  122  which may be continuously fed to the part to form a continuous weld. In TIG mode the electrode is not melted, and generally only the base metal is melted. 
     The power supply  110  may control the output voltage and the output current, as well as the feeding of the wire to optimize the welding process. In addition, the power supply  110  may be connected to one group of accessories  124  including for example a remote wire feeder  126 , a spool gun  128 , or a push/pull gun  130 . Further, the power supply  110  may be connected to other groups of accessories  132 , for example through an 8-pin connector. The second group of accessories  132  may include a MIG gun  134 , a smart gun  136 , a foot pedal  138 , a pendant  140 , a TIG gun  142 , and/or a remote control/trigger  144 . 
     Within the power supply  110 , the input power  112  may be provided to a circuit breaker or switch  154 . Power may be provided from the circuit breaker  154  to a power circuit  150 . The power circuit  150  may condition the input power to provide a welding output power  116 , as well as, for powering various additional accessories to support the welding process. The power circuit  150  may also be in communication with the control circuit  152 . The control circuit  152  may allow the user to control various welding parameters, as well as, providing various control signals to the power circuit  150  to control various aspects of the welding process. The power from the circuit breaker  154  may be provided to an EMI filter  156  of the power circuit  150 . Power is provided from the EMI filter  156  to an input bridge  158 . Power may be provided from the input bridge  158  to a conditioning circuit  162 . The conditioning circuit  162  may include a boost circuit, a transformer, as well as a power factor correction circuit. 
     Power is provided from the conditioning circuit  162  to the inverter  160  where the power is converted to a DC signal  114  thereby providing welding output power  116 . Power may also be provided to a bias circuit  170  to power a number of accessories internal or external to the power supply  110  that facilitate operation of the power supply and welding process. For example, the bias circuit  170  may provide power to gas solenoid valves  172 , fans  174 , as well as, other accessory devices. In addition, power is provided to a motor drive circuit  164  that is in communication with a motor  166 . The motor  166  may be in communication with a feed mechanism  168  configured to feed wire  122  to a weld gun for use in creation of the weld. The control circuit  152  may provide control signals to any of the previously mentioned circuits in the power circuit  150  to optimize the weld process and performance of the power supply  110 . The control circuit  152  may include a pulse width modulator  182  and a processor  184  for analyzing various weld characteristics and calculating various weld parameters according to user settings, as well as, various feedback signals. In addition, an interface circuit  186  may be provided to control a display  188  that may provide information to the user of the welding system. The display  188  may include an LED display, a LCD display, or various other known display technology. The display may provide various menu choices to the user, as well as, providing various feedback on the welding process including the values of various parameters or graphs of previous welding characteristics. The controls  190  may also be in communication with the interface circuit  186  to allow the user to provide input such as various welding parameters to control the operation of the welding process. 
     The power supply  110  may further include a voltage reducing device (VRD) circuit  192 , a low-power circuit that detects contact between the part  118  to be welded and the electrode. When an open circuit condition is detected between the electrode and the work piece, the VRD circuit  192  may reduce the maximum open circuit voltage to safe levels. When contact is made and/or the load is below a threshold resistance, the VRD circuit  192  may no longer reduce the voltage and thus may allow the welding system  100  to operate at full power. The VRD circuit  192  may be in communication with a timer  194 . The timer  194  may be implemented as software as part of the control circuit  152 , or may be comprised of an electronic circuit. 
     Now referring to  FIG. 2 a   , a housing  200  is provided that may be implemented with the welding system  100 . The housing  200  may contain the power supply  110 , and may further include a user interface  202  and a front connection panel  204 . The front connection panel  204  may, for example, be used for connecting the power supply  110  to the first and second groups of accessories  124  and  132 , as discussed above. 
     Now referring to  FIG. 2 b   , a particular implementation of a user interface  202  is provided that may include various inputs selectable by a user and various indicators and displays. A power indicator  210  may indicate when the power supply  110  is receiving the input power  112 . A fault light  220  may indicate when the welding process has entered a fault condition. A VRD “on” indicator  230  may indicate when the VRD is on, and a VRD “off” indicator  232  may indicate when the VRD is off. 
     A mode selection input  240  may allow the user to select a desired welding process. The mode selection input  240  may be a button which when pressed causes the power supply  100  to cycle through and select a welding process. Three welding process indicators  242 ,  244 ,  246  may respectively light upon selection of, for example, MIG, TIG, or stick welding. The MIG selection provides a suitable configuration for both gas metal arc welding and flux core arc welding. 
     A trigger interlock input  270  may allow a user to select between 2T and 4T modes for MIG, TIG and stick welds that are activated via an electric switch. The 2T mode allows the user to push and hold the switch to activate and release the switch to deactivate. The 4T mode allows the user to push and release the switch to activate, then push and release the switch again to deactivate. An indicator  272  may light when the 2T mode is selected, and an indicator  274  may light when the 4T mode is selected. 
     An amperage input  252  may allow a user to select a desired output current. A wire feed speed input  254  may allow a user to select a desired wire feed speed of the wire  122 . The desired wire feed speed may be a desired steady-state wire feed speed. In some implementations, the inputs  252  and  254  may be combined into an adjustable knob. A user may press the adjustment knob to cycle between the inputs  252  and  254 , and then turn the adjustment knob to select a desired value of the current or wire feed speed. The selected desired value may be displayed on a display  250 , which may be a super bright red LED display. 
     A voltage input  262  may allow a user to select a desired output voltage of the welding signal. An inductance input  264  may allow a user to select a desired inductance which, for example, may optimize weld bead characteristics. An arc force input  266  may allow a user to select desired properties of arc force. A down slope input  268  may allow a user to select a down slope time, which is a function of the down ramp rate of the output current. In some implementations, the inputs  262 ,  264 ,  266 , and  268  may be combined into an adjustable knob. A user may press the adjustment knob to cycle between the inputs  262 ,  264 ,  266 , and  268 , and then turn the adjustment knob to select a desired value of the voltage, inductance, arc force, or down slope. The selected desired value may be displayed on a display  260 , which may be a super bright red LED display. 
     An advanced features input  280  may allow a user to select menus and toggle through various further inputs, which are displayed on the displays  250  and  260 . A MIG welding main menu may provide inputs for operation control, pre-flow, spot on/off, spot time, stitch on/off, stitch time, dwell time, run-in percentage, post-flow, burn back time, wire sharp, and/or a setup submenu. The setup submenu may provide inputs for wire feed units, amperage calibration, voltage calibration, wire speed calibration, arc hour display, VRD (on, off or triggered), total weld energy (for heat input computation), and/or factory defaults. A stick welding main menu may provide inputs for operation control, hot start on/off, hot start time, hot start amperage, and/or a setup submenu. The setup submenu may provide inputs for arc hour display, VRD disable, and factory defaults. The TIG main menu may provide inputs for operation control, pre-flow, post-flow, and a setup submenu. The setup submenu may provide inputs for arc hour display, VRD disable, and factory defaults. 
     Burn back time may refer to an adjustable period of time that the power supply  110  may provide power for the welding process after the wire feed stops in order to burn back the wire and prevent it from sticking in the weld puddle. Wire sharp refers to the application of predefined current outputs applied to the wire, for example, a rapid series of powerful current pulses after the motor  166  is de-energized. This prevents a ball of molten metal from freezing on the end of the welding wire, and tapers the end of the weld wire to a sharp point, promoting a cleaner start when welding resumes. The current outputs terminate when an open-circuit is detected or after a predefined time or condition is reached. Run-in percentage refers to a percent of wire feed speed. The percentage may range, for example, from about 25 percent to about 150 percent of the wire feed speed. The run-in setting may, for example, allow a user to temporarily alter the selected wire feed speed to optimize MIG weld start characteristics. 
     The control circuit  152  may receive each of the quantities respectively associated with each of the inputs. Further, although the above inputs are shown in particular implementations, each of the inputs may be configured as a dial, adjustment knob, button, or switch, for example. Additionally, in some implementations, some of the inputs may be automatically selected by the control circuit  152 . Which inputs are automatically selected and which inputs are user-selectable may depend on which welding process is selected. In some implementations, some parameters, for example wire diameter, material, gas, and joint design, may not be programmed into the control circuit  152 . 
     Now referring to  FIG. 3 , one implementation of a circuit  300  having the voltage reducing circuit (VRD)  192  is provided. The inverter  160  may be connected with the part  118  to be welded and the electrode  118 . The VRD circuit  192  may be placed parallel to the inverter  160 . During operation, one of the VRD circuit  192  and the inverter  160  may provide a voltage that will complete the circuit between electrode  310  (e.g. the stick  120  or wire  122 ) and the part  118  to be welded. The VRD circuit  192  provides a low voltage relative to the full voltage provided by the inverter  160 . For example, the low voltage provided for VRD circuit  192  would be under 35 volts, while the welding voltage would be well over 50 volts. Voltage and/or current feedback circuits  320  may detect a resultant voltage or current due to completion of the circuit with the VRD circuit  192  or the inverter  160 . For any of the welding processes described herein, particularly those using non-consumable electrodes (e.g. stick  120 ), but also processes using a consumable electrode (e.g.  122 ), the voltage and/or current feedback circuits  320  can be used to detect whether or not a welding operation is in progress based on a detection of whether the part  118  to be welded is in contact with the electrode  310 . Additionally or alternatively, for welding processes using a consumable electrode (e.g. wire  122 ), whether or not a welding operation is in progress can be detected based on whether a user presses a trigger on, for example, MIG gun  134 , a smart gun  136 , a foot pedal  138 , a pendant  140 , and/or a remote control/trigger  144 . Therefore, in each instance where the method of  FIG. 4 , as described below, detects whether contact is made by detecting contact, it is understood that such detection can also be made by determining whether the trigger is pressed. Full operation of the circuit  300  will be understood with reference to method  400  and  FIG. 4 . 
     Now referring to  FIG. 4 , a method  400  is provided for energy conservation and improved cooling in arc welding machines. The method  400  was developed for shielded metal arc welding (SMAW), which is typically practiced without use of trigger mechanisms so requires continuous electrification of the consumable electrode, but the method may be utilized in a variety of welding processes, for example gas metal arc welding, flux core arc welding, or tungsten inert gas welding. The ordering of the steps presented herein is merely one implementation of the method  400 . Those skilled in the art will recognize that the ordering may be varied, that some steps may occur simultaneously, that some steps may be omitted, and that further steps may be added. Moreover, each step involving the controller may be implemented by configuring (e.g. programming) the controller to perform the step. 
     The method starts in block  410 . In block  410 , the welding system  100  may be powered up, and the VRD circuit  192  may be initially turned off, the inverter  160  may be turned on, and one or more fans  174  may be turned on. 
     In block  420 , when the voltage and/or current feedback circuits  320  determine that a welding operation is stopped or not running, the timer  194  in communication with the VRD circuit begins running  194 . The method  400  detects whether a welding operation has begun, for example by using the voltage and/or current feedback circuits  320  detects whether the part  118  to be welded is in contact with the electrode  310  or detecting if the trigger is pulled. The timer  194  may determine whether a first predefined period of time has elapsed before the system detects welding, for example by detecting contact between the part  118  and the electrode  310  or the trigger is pulled. The first predefined period of time may be about 5, about 10, about 15, or about 20 minutes from the end of the welding process, but in various implementations may take on a value from between about 5 minutes to about 10 minutes, or between about 5 to about 15 minutes, or between about 5 to about 20 minutes, or between about 10 to about 15 minutes, or between about 10 to about 20 minutes, or between about 15 to about 20 minutes, for example. In some implementations, the method  400  may use a first period of time that is not predetermined. Rather, the first period of time may depend on welding conditions or feedback during the welding process. Additionally or alternatively, the first period of time or the first predefined period of time may depend on various pre-selected welding parameters. 
     If the first predefined period elapses without the voltage and/or current feedback circuits  320  detecting contact between the part  118  and the electrode  310  or the trigger being pulled, thus indicating that the welding process has been idle for the first predefined period of time, then the method  400  may proceed to block  430 . If the voltage and/or current feedback circuits  320  detect a welding operation before the first predefined period of time elapses, then the method  400  may proceed to block  450 . Throughout the first predefined period of time, that is, after the first predefined period of time begins and before the first predefined period of time elapses, the inverter  160  continues to provide welding output voltage. 
     In block  430 , the VRD circuit  192  may be turned on and the inverter  160  may be turned off, thus reducing the maximum open circuit voltage to safe levels as long as no welding operation is detected. Additionally, the one or more fans  174  may be left on to cool the power supply  110 . Now, the VRD circuit  192  provides a low voltage to allow the voltage and/or current feedback circuits  320  to detect the start of a welding operation by detecting whether the part  118  to be welded is in contact with the electrode  310 . 
     The timer  194  may continue running, and the system detects if a second predefined period of time elapses before the voltage and/or feedback circuits  320  detect a welding operation, or if the voltage and/or feedback circuits  320  detect a welding operation before the second predefined period of time elapses. The second predefined period of time may begin counting at the start of block  430 , that is, when the first predefined period of time elapses. Although, in some implementations, the time periods could have the same starting time or offset starting times such that the periods could be overlapping or discontinous. The second predefined period of time may be about 5, about 10, about 15, or about 20 minutes from the end of the first predefined time period, but in various implementations may take on a value from between about 5 minutes to about 10 minutes, or between about 5 to about 15 minutes, or between about 5 to about 20 minutes, or between about 10 to about 15 minutes, or between about 10 to about 20 minutes, or between about 15 to about 20 minutes, for example. In some implementations, the method  400  may use a second period of time that is not predetermined. Rather, the second period of time may depend on welding conditions or feedback during the welding process. For example, one or more thermistors or other thermal sensors may be coupled to one or more of a transformer, inductor, transistor, diode, or other component prone to heating, and the second period of time may based on the feedback of the one or more thermal sensors. In other examples, the feedback could directly be used to determine when the fan will be deactivated. That is, the fan may be shut down based on the feedback, for example when the feedback crosses a threshold (e.g. a measured temperature falls below a temperature threshold). Additionally or alternatively, the second period of time or the second predefined period of time may depend on various pre-selected welding parameters. 
     If the second predefined period of time elapses before contact between the part  118  and the electrode  310  is detected or the trigger is pulled, then the method  400  proceeds to block  440 . If contact between the part  118  and the electrode  310  is detected, meaning that a welding operation is detected, before the second predefined period of time elapses, then the method  400  proceeds to block  450 . 
     In block  440 , the VRD circuit  192  may remain on and the inverter  160  may remain off. However, the one or more fans  174  may be turned off. Once the voltage and/or current feedback circuits  320  detect contact between the part  118  and the electrode  310  is detected or the trigger is pulled, meaning that a welding operation is detected, then the method proceeds to block  450 . 
     In block  450 , the part  118  and the electrode  810  may be in contact or the trigger may be pulled and the user may be starting to weld. As such, the VRD circuit  192  may be turned off and the inverter  160  may be turned on, thus allowing the welding system  100  to operate at full welding voltage. Additionally, the fan may be turned on. However, if it is detected that welding has stopped, for example by determining that the part  118  and electrode  310  are no longer in contact, the method  400  may return to block  420  and the timer  194  may be reset and begin counting the first predefined period of time. 
     Combination of the VRD circuit  192  with the timer  194  provides improved cooling and energy benefits relative to a system with no VRD circuit  192 . At the same time, the combination of the VRD circuit  192  and the timer  194  ensures superior starting characteristics not found in a system with a VRD circuit  192  but no timer  194 . 
     Any of the controllers, control circuits, modules, servers, or engines described may be implemented in one or more computer systems or integrated controllers. One exemplary system is provided in  FIG. 5 . The computer system  1000  includes a processor  1010  for executing instructions such as those described in the methods discussed above. The instructions may be stored in a computer readable medium such as memory  1012  or storage devices  1014 , for example a disk drive, CD, or DVD, or in some form of nonvolatile memory, internal or external to the processor, such as EPROM or flash. The computer may include a display controller  1016  responsive to instructions to generate a textual or graphical display on a display device  1018 , for example a computer monitor. In addition, the processor  1010  may communicate with a network controller  1020  to communicate data or instructions to other systems, for example other general computer systems. The network controller  1020  may communicate over Ethernet or other known protocols to distribute processing or provide remote access to information over a variety of network topologies, including local area networks, wide area networks, the Internet, or other commonly used network topologies. 
     In other embodiments, dedicated hardware implementations, such as application specific integrated circuits, programmable logic arrays and other hardware devices, can be constructed to implement one or more of the methods described herein. Applications that may include the apparatus and systems of various embodiments can broadly include a variety of electronic and computer systems. One or more embodiments described herein may implement functions using two or more specific interconnected hardware modules or devices with related control and data signals that can be communicated between and through the modules, or as portions of an application-specific integrated circuit. Accordingly, the present system encompasses software, firmware, and hardware implementations. 
     In accordance with various embodiments of the present disclosure, the methods described herein may be implemented by software programs executable by a computer system or processor. Further, in an exemplary, non-limited embodiment, implementations can include distributed processing, component/object distributed processing, and parallel processing. Alternatively, virtual computer system processing can be constructed to implement one or more of the methods or functionality as described herein. 
     Further, the methods described herein may be embodied in a computer-readable medium. The term “computer-readable medium” includes a single medium or multiple media, such as a centralized or distributed database, and/or associated caches and servers that store one or more sets of instructions. The term “computer-readable medium” shall also include any medium that is capable of storing, encoding or carrying a set of instructions for execution by a processor or that cause a computer system to perform any one or more of the methods or operations disclosed herein. 
     As a person skilled in the art will readily appreciate, the above description is meant as an illustration of the principles of this invention. This description is not intended to limit the scope or application of this invention in that the invention is susceptible to modification, variation and change, without departing from spirit of this invention, as defined in the following claims.