Patent Publication Number: US-2021162530-A1

Title: Method and Apparatus for Temperature Characterization in Welding

Description:
RELATED APPLICATIONS 
     This patent is a continuation-in-part of U.S. patent application Ser. No. 16/995,018, filed Aug. 17, 2020, entitled “Method and Apparatus for Temperature Characterization in Welding,” and claims priority to U.S. Provisional Patent Application Ser. No. 62/890,181, filed Aug. 22, 2019, entitled “Method and Apparatus for Temperature Characterization in Welding.” The entireties of U.S. patent application Ser. No. 16/995,018 and U.S. Provisional Patent Application Ser. No. 62/890,181 are incorporated herein by reference. 
    
    
     BACKGROUND 
     The present disclosure relates to heating a workpiece for welding, and more particularly, to a method and apparatus for temperature characterization for optimally heating a workpiece for welding. 
     Induction heating is a method for producing heat in a localized area on a susceptible metallic object. Induction heating involves applying an AC electric signal to a heating loop or coil placed near a specific location on or around the metallic object to be heated. The varying or alternating current in the loop creates a varying magnetic flux within the metal to be heated. Current is induced in the metal by the magnetic flux, thus heating it. Induction heating may be used for many different purposes including curing adhesives, hardening of metals, brazing, soldering, and other fabrication processes in which heat is a necessary or desirable agent. 
     Limitations and disadvantages of conventional systems for heating a workpiece for welding will become apparent to one of skill in the art, through comparison of such approaches with some aspects of the present method and system set forth in the remainder of this disclosure with reference to the drawings. 
     SUMMARY 
     Methods and systems are provided for temperature characterization in welding, substantially as illustrated by and described in connection with at least one of the figures, as set forth more completely in the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and/or other aspects will become apparent and more readily appreciated from the following description of some various aspects of examples of the disclosure, taken in conjunction with the accompanying drawings. 
         FIG. 1  is a high-level block diagram of an example heating system, in accordance with aspects of the disclosure. 
         FIG. 2  shows a block diagram of an example control circuitry, in accordance with aspects of the disclosure. 
         FIG. 3  shows a flow diagram representative of example machine readable instructions, which may be executed by the example control circuitry of  FIGS. 1 and/or 2  to implement the example heating system of  FIG. 1 . 
         FIG. 4  shows a detailed flow diagram representative of example machine readable instructions, which may be executed by the example control circuitry of  FIGS. 1 and/or 2  to implement the example heating system of  FIG. 1 . 
         FIG. 5  shows a flow diagram representative of example machine readable instructions, which may be executed by the example control circuitry of  FIGS. 1 and/or 2  to implement the example heating system of  FIG. 1 . 
     
    
    
     The figures are not necessarily to scale. Where appropriate, similar or identical reference numbers are used to refer to similar or identical components. 
     DETAILED DESCRIPTION 
     Various examples of the disclosure improve heating of a workpiece (e.g., a workpiece to be welded, brazed, etc.) to a target temperature by improving the accuracy of the heated workpiece temperature. For example, when working with smaller workpieces, a workpiece may be easily overheated by conventional heating systems because of the lower thermal mass of such workpieces. In some cases, overheating can damage the workpiece and/or delay performance of the welding operation. Therefore, conventional methods to avoid overheating the workpiece involve an operator closely attending to heating of the workpiece for welding, which may lead to inefficient use of time. When the workpiece is not sufficiently heated (e.g., is heated to less than the target temperature to avoid overheating), extra time may be needed for the actual welding process since the workpiece now needs additional time to be heated to the required temperature. Insufficient heating may lead to greater chances of failed weld, and may result in rejection of a weld done according to a weld procedure specification (WPS). 
     Therefore, when using, for example, a thermostatically controlled induction heating system to bring a workpiece to a desired temperature, users must be vigilant to ensure that undesired overheating does not occur due to the improper placement or slow response of a temperature sensing device. Monitoring can be particularly important when a heating capacity of a heating device, such as, for example, an induction heating device, exceeds what is required to heat a given workpiece and results in very short heating times. 
     The situations described above can occur, for example, where users are heating a workpiece with a small thermal mass and/or while using a temperature sensing device that may be poorly thermally coupled to the workpiece (e.g., armored temperature sensing device, temperature sensing device not tightly placed against the workpiece, etc.). However, overheating and/or poor thermal coupling may occur with workpieces of any size. 
     In the disclosed examples, the user need not manually calculate and set power limits to reduce the temperature overshoot when heating a workpiece. By increasing the accuracy of heating the workpiece and reducing the overshoot of poorly thermally coupled temperature sensing devices, the user can better make use of temperature sensing devices such as, for example, armored temperature sensing devices in various situations, which can result in quicker setup for the user. Disclosed example systems and methods can also aid in reducing wear on heating tools by limiting potential temperature overshoot past safe tool operating limits. 
       FIG. 1  is a high-level block diagram of an example heating system, in accordance with aspects of the disclosure. Referring to  FIG. 1 , there is shown an example heating system  100  that comprises a control circuitry  105  configured to control a heating device  110  suitable for heating a workpiece  130 , and sensors  120  suitable for monitoring a temperature of the workpiece  130 . The heating system  100  may use any type of a heating system, and an example heating system may be an induction heating system. 
     Accordingly, the example heating device  110  is described in this disclosure for the heating system  100 . The heating device  110  comprises induction heating power supply  104 , conductors  106 , and a heating coil  108 . The heating system  100  is configured to provide power from the induction heating power supply  104  to the heating coil  108  via the conductors  106 . The heating coil  108  is magnetically coupled to the workpiece  130  that is to be heated via the heating device  110 . In operation, the induction heating power supply  104  outputs power to the heating device  110  at a heating frequency, which transfers the power to the workpiece  130  to inductively heat the workpiece  130 . The heating power supply  104  may be coupled to the heating device  110  via an extension cable. 
     The temperature of the workpiece  130  can be monitored at various locations by the sensors  120 , which may comprise, for example, temperature sensors. The sensors  120  may be any type of sensors suitable for monitoring the temperature of a welding workpiece, such as, for example, armored temperature sensing devices or spot-welded sensing devices. 
     The control circuitry  105  is configured to monitor and control various functions. For example, the control circuitry  105  can monitor temperature information from the sensors  120  so that the heating device  110  can be controlled to appropriately control the temperature of the workpiece  130 . The control circuitry  105  can also characterize, based on the received inputs from the sensors  120  and a user via a user interface (e.g., input devices  242  in  FIG. 2 ), a temperature ramp rate for a workpiece so that it can be heated to the desired temperature without overheating the workpiece. 
     The control circuitry  105  comprises a hardware device capable of executing instructions to perform specific functions. Accordingly, the control circuitry  105  comprises any of a number of different types of processors, memory, logic circuitry, etc. for controlling the heating device  110 . 
     An example heating coil  108  may include two or more conductors and a turn connector. The conductors (and, by extension, the heating coil  108 ) may be conformably wrapped around the workpiece  130  while the conductors are not electrically connected in series. The example heating coil  108  may comprise, for example, an induction heating blanket, an induction heating assembly, etc. The turn connector connects the two or more conductors in series to configure the first and second conductors as an inductor having two or more turns. The example heating coil  108  may include one or more electrical and/or thermal insulators to, for example, prevent short circuiting and/or protect the conductors from heat induced in the workpiece  130 . 
       FIG. 2  shows a block diagram of an example control circuitry, in accordance with aspects of the disclosure. Referring to  FIG. 2 , there is shown an example control circuitry  200  that may be used with various examples of the disclosure, and may be similar to the control circuitry  105  in  FIG. 1 . The control circuitry  200  may comprise, for example, a processor  210 , memory  220 , a communication interface  230 , and an IO interface  240 . The processor  210  may comprise, for example, one or more of processors (CPUs, GPUs, etc.), controllers, system on chips, ASICs, etc. 
     The memory  220  may include non-volatile memory  226  and volatile memory  228 . The storage described for holding local data may be part of the memory  220  or comprise separate memory. The operating system  222  and applications  224  may be stored in, for example, the non-volatile memory  226 , and may be copied to volatile memory  228  for execution by the processor  210 . Various aspects of the disclosure may use different memory architectures that are design and/or implementation dependent. For example, some aspects of the disclosure may have the operating system  222  and applications  224  in the non-volatile memory  226  executed at least in part from the non-volatile memory  226 . 
     The communication interface  230  may allow the control circuitry  200  to communicate with other devices via, for example, a wired protocol such as USB, Ethernet, Firewire, etc., or a wireless protocol such as Bluetooth, Near Field Communication (NFC), Wi-Fi, etc. The wired or wireless protocol may also be, for example, a proprietary protocol. The various types of radios for communication may be referred to as a transceiver for the sake of simplicity. The communication may be, for example, with various sensors and/or devices that can relay sensor data. The communication interface  230  may also be used to communicate with other networks such as local networks, cellular networks, etc. Additionally, the communication interface may allow various devices to plug into, for example, a USB ports. For example, a keyboard and/or a mouse may plug into their respective USB ports, or communicate wirelessly to a USB dongle that allows wireless communication with, for example, a wireless keyboard and/or mouse. 
     The control circuitry  200  may also comprise the IO module  240  for communication with a user via the input devices  242  and output information to be displayed on output devices  244 . The input devices  242  may comprise, for example, switches, slide switches, membrane switches, buttons, touch sensitive screen, which may be a part of a display, a microphone, etc. The touch sensitive screen (touchscreen) may have soft buttons, switches, slide switches, keyboard, etc. that emulate their physical counterparts. The input devices  242  may also comprise, for example, a keyboard, a mouse, a trackball, etc., as well as various sensors, cameras, etc. The input devices  24  may additionally comprise, for example, bar code readers and/or other type of scanners that may be used to identify an object. The output devices  244  may comprise, for example, display(s), speaker(s), LED(s), vibration motor(s), etc. Some devices such as a touchscreen are able to provide both input and output functions of the IO module  240 . 
     The processor  210  may operate using different architectures in different examples of the disclosure. For example, the processor  210  may use the memory  220  to store instructions to execute, or the processor  210  may have its own memory (not shown) for its instructions. 
     Various examples may use other architectures where the different functionalities may be grouped differently. For example, the functionalities may be in different integrated circuit chips, or different devices may be combined. For example, the IO module  240  and the communication interface  230  may be combined together. Additionally, the control circuitry  200  may refer logically to various physical devices. For example, one or more of the output devices  244  may be part of a different integrated circuit or on a different printed circuit board than one or more of the input devices  242 . 
       FIG. 3  shows a flow diagram representative of example machine readable instructions  300 , which may be executed by the example control circuitry  105 ,  200  of  FIGS. 1 and/or 2  to implement the example heating system  100  of  FIG. 1 . For example, the instructions  300 , which may be in an application  224 , may be executed by the processor  210  to control the heating device  110  to heat a workpiece  130  to a target temperature. An induction heating device is used as an example for the heating device  110 , and it should be understood that various examples of the disclosure may use any type of heating device appropriate for a purpose such as, for example, welding. 
     In block  302 , a start request for heating is received. In block  304 , the heating device  110 , for example, an induction heating device, is enabled. In block  306 , a target temperature T T  to which the workpiece  130  should be heated is received. The target temperature may be, for example, entered or selected by a user via the input devices  242  or received from another electronic device wirelessly and/or by wired communication via the communication interface  230 . The workpiece  130  may also recognized by scanning an identification mark such as, for example, a bar code, with an input device  242 , optically recognized by an application  224 , etc., and then the target temperature looked up in, for example, a look-up table in the memory  220 . 
     In block  308 , the control circuitry  105  receives, wirelessly and/or via wire conductors, outputs from one or more sensors  120 , each configured to monitor a temperatures at a location of the workpiece  130 . The temperature monitoring may occur continuously or at some time interval. When the target temperature T T  is received or determined, the control circuitry  105  will select the highest temperature T H  for the workpiece  130  monitored via the sensors  120 . 
     In block  310 , the target temperature T T  is compared to the highest temperature T H . Depending on the result of the comparison, the control temperature T C  is set in block  312 .  FIG. 4  describes block  312  in more detail. 
     In block  314 , the heating device  110  heats the workpiece  130  to the control temperature T C , or to substantially the control temperature T C  as allowed by the heating system  100 . “Substantially the control temperature T C ” may be a temperature within a pre-determined margin to the temperature T C  that may be pre-determined for a given usage. The pre-determined margin may depend on various parameters, such as, for example, the type of metal being heated, the type of heating device  110 , etc. Accordingly, “substantially the control temperature T C ” may be set by the processor  210 , by the user using any of the input devices  242 , or via commands received with the communication interface  230 . 
     As examples, the margin for an application may be within 10% of the control temperature T C  in one case, 5% of the control temperature T C  in another case, 1% of the control temperature T C  in another case, etc. Therefore, as the margin may differ for different cases, the specific margins given as examples above do not limit any examples of the disclosure. 
     When the heating system  100  monitors the sensors  120  periodically, the temperature of the workpiece  130  may be at a temperature that is below or above the control temperature T C . The monitoring period may adjustable in some examples of the disclosure, while other examples of the disclosure may have a fixed monitoring period. The monitoring period used may be variable in some examples of the disclosure while other examples of the disclosure may have a fixed monitoring period. That is, the monitoring period may change while monitoring the workpiece  130  or the monitoring period may remain the same for a first workpiece  130  but may be changed for a second workpiece  130 . The monitoring period may be timed via a software timer in, for example, the operating system  222  or the applications  224 , or a hardware timer that may be a part of, for example, the control circuitry  105 . 
     Some examples involve determining that the control temperature T C  is reached when the temperature is within a temperature range. The temperature range may be fixed or variable depending on various parameters such as, for example, the interval at which the temperature of the workpiece is determined, the characteristics of the workpiece, etc. 
     In block  316 , the control circuitry  105  disables the heating device  110  to stop heating the workpiece  130  when the highest temperature T H  from any of the various sensors  120  indicates that the workpiece  130  has reached the control temperature T C  or is at substantially the control temperature T C . 
     In block  318 , the control circuitry  105  monitors the continuing rise in overshoot temperature of the workpiece  130  based on the outputs of the sensors  120 . Once the outputs of the sensors  120  indicate that the temperature of the workpiece  130  has peaked, the temperature overshoot, which is the difference in temperature from the control temperature T C  to the peak temperature, and the overshoot time, which is the time period from when the heating device  110  is disabled to the workpiece  130  reaching its peak temperature, are determined. 
     In block  320 , a temperature ramp rate is determined by, for example, the processor  210  of the control circuitry  105  based on the temperature overshoot and/or the overshoot time for use in heating the workpiece  130  to the target temperature T T . The temperature ramp rate may be a linear ramp or a non-linear ramp. An example of a linear ramp may be, for example, increasing the control temperature T C  for the workpiece  130  by a constant temperature amount per unit time until the target temperature T T  is reached without overshooting beyond an acceptable margin. The control temperature T C  may be increased, for example, periodically. 
     In some other examples, the control circuitry  105  controls the temperature of the heating device  110  periodically such that the temperature of the workpiece reaches substantially the target temperature T T  without overshooting beyond an acceptable margin. “Substantially the target temperature T T ” may be a temperature within a margin to the target temperature T T  that may be pre-determined for a given usage. The margin may depend on various parameters, such as, for example, the type of metal being heated, the type of heating device  110 , etc. Accordingly, “substantially the target temperature T T ” may be set by the processor  210 , by the user using any of the input devices  242 , or via commands received with the communication interface  230 . 
     As examples, the margin for an application may be within 5% of the target temperature T T  in one case, 2% of the target temperature T T  in another case, 1% of the target temperature T T  in another case, etc. Therefore, as the margin may differ for different cases, the specific margins given as examples above do not limit any examples of the disclosure. 
     The heating period used may be variable in some examples of the disclosure while other examples of the disclosure may have a fixed period. That is, the heating period may change while heating the workpiece  130  or the heating period may remain the same for a first workpiece  130  but may be changed for a second workpiece  130 . The heating period may be timed via a software timer in, for example, the operating system  222  or the applications  224 , or a hardware timer that may be a part of, for example, the control circuitry  105 . 
     A single timer may be used for monitoring the temperature of the workpiece  130  and for using the temperature ramp rate in heating the workpiece  130 , or independent timers may be used. The workpiece  130  may be heated to an interim temperature T I  that is raised, for example, periodically based on the temperature ramp rate. 
     In block  322 , the control circuitry  105  enables the heating device  110  to heat the workpiece  130  to the target temperature T T  using the temperature ramp rate. An example of the disclosure may increase a target temperature of the workpiece  130  to an interim temperature T I  periodically until the interim temperature T I  equals the target temperature T T . Accordingly, the heating device  110  can heat the workpiece  130  according to the increasing interim temperature T I  until the target temperature T T  is reached. 
     In block  324 , when the workpiece  130  reaches the target temperature T T , or reaches substantially the target temperature T T , the heating device  110  is disabled. 
     While an example flow diagram is shown in  FIG. 3  for illustrative purposes, it should be understood that various other flow diagrams may also describe other examples of the disclosure. For example, in another example of the disclosure, the blocks  306  and  308  may happen serially in either order rather than in parallel as shown in  FIG. 3 . 
       FIG. 4  shows a detailed flow diagram representative of example machine readable instructions  300 , which may be executed by the example control circuitry  105 ,  200  of  FIGS. 1 and/or 2  to implement the example heating system of  FIG. 1 . The example instructions  400  may be performed to implement block  312  of  FIG. 3  to set the control temperature T C . 
     In block  402 , the comparison of the target temperature T T  to the current highest temperature T H  performed by the processor  210  is used. In block  404 , in an example algorithm in the application  224  executed by the processor  210 , when the difference between the target temperature T T  and the current highest temperature T H  is larger than a threshold value (T R ), the control temperature T C  is set to: 
         T   C   =T   H   +m *( T   R   −T   H )  (Equation 1)
 
     where ‘m’ is less than or equal to 1 and greater than or equal to 0. 
     Some examples of the disclosure may set ‘m’ to be in the range of, for example, substantially 0.15 to substantially 0.75. An example of the disclosure may set ‘m’ to, for example, substantially 0.25. Furthermore, some examples of the disclosure may set the threshold value (T R ) to be in the range of, for example, substantially 10° C. to substantially 50° C. An example of the disclosure may set the threshold value (T R ) to, for example, substantially 25° C. 
     In an example algorithm, when the difference between the target temperature T T  and the current highest temperature T H  is less than or equal to the threshold value (TH 1 ), the control temperature T C  is set by the processor  210  to the target temperature T T : 
         T   C   =T   T   (Equation 2)
 
     Accordingly, in some examples, the heating system  100  is configured to control the heating device  110  based on the received target temperature (T T ), the temperature ramp rate, and feedback based on the outputs of the sensors  120 . 
       FIG. 5  shows a flow diagram representative of example machine readable instructions  500 , which may be executed by the example control circuitry  105 ,  200  of  FIGS. 1 and/or 2  to implement the example heating system  100  of  FIG. 1 . For example, the instructions  500 , which may be in an application  224 , may be executed by the processor  210  to control the heating device  110  to heat a workpiece  130  to a target temperature. An induction heating device is used as an example for the heating device  110 , and it should be understood that various examples of the disclosure may use any type of heating device appropriate for a purpose such as, for example, welding. 
     In block  502 , a start request for heating is received. In block  504 , the heating device  110 , for example, an induction heating device, is enabled. In block  506 , a target temperature T T  to which the workpiece  130  should be heated is received. The target temperature may be, for example, entered or selected by a user via the input devices  242  or received from another electronic device wirelessly and/or by wired communication via the communication interface  230 . The workpiece  130  may also recognized by scanning an identification mark such as, for example, a bar code, with an input device  242 , optically recognized by an application  224 , etc., and then the target temperature looked up in, for example, a look-up table in the memory  220 . 
     In block  508 , the control circuitry  105  receives, wirelessly and/or via wire conductors, outputs from one or more sensors  120 , each configured to monitor a temperatures at a location of the workpiece  130 . The temperature monitoring may occur continuously or at some time interval. The control circuitry  105  selects a current temperature (T S ) for the workpiece  130  monitored via the sensors  120 . For example, the control circuitry  105  may receive a selection of one or more of the sensors  120  (e.g., via the I/O module  240 , the input devices  242 ) as a control sensor for characterization of the workpiece and/or control of heating. In some examples, the control circuitry  105  selects the current temperature (T S ) as the highest observed temperature (e.g., the highest temperature T H  of  FIG. 3 ). 
     In block  510 , the target temperature T T  is compared to the selected current temperature T S . Depending on the result of the comparison, the control temperature T C  is set in block  512 . Block  512  may be implemented using a process such as the process of  FIG. 4 , using the selected current temperature instead of the highest monitored temperature T H . 
     In block  514 , the heating device  110  heats the workpiece  130  to the control temperature T C , or to substantially the control temperature T C  as allowed by the heating system  100 . “Substantially the control temperature T C ” may be a temperature within a pre-determined margin to the temperature T C  that may be pre-determined for a given usage. The pre-determined margin may depend on various parameters, such as, for example, the type of metal being heated, the type of heating device  110 , etc. Accordingly, “substantially the control temperature T C ” may be set by the processor  210 , by the user using any of the input devices  242 , or via commands received with the communication interface  230 . 
     As examples, the margin for an application may be within 10% of the control temperature T C  in one case, 5% of the control temperature T C  in another case, 1% of the control temperature T C  in another case, etc. Therefore, as the margin may differ for different cases, the specific margins given as examples above do not limit any examples of the disclosure. 
     When the heating system  100  monitors the sensors  120  periodically, the temperature of the workpiece  130  may be at a temperature that is below or above the control temperature T C . The monitoring period may adjustable in some examples of the disclosure, while other examples of the disclosure may have a fixed monitoring period. The monitoring period used may be variable in some examples of the disclosure while other examples of the disclosure may have a fixed monitoring period. That is, the monitoring period may change while monitoring the workpiece  130  or the monitoring period may remain the same for a first workpiece  130  but may be changed for a second workpiece  130 . The monitoring period may be timed via a software timer in, for example, the operating system  222  or the applications  224 , or a hardware timer that may be a part of, for example, the control circuitry  105 . 
     Some examples involve determining that the control temperature T C  is reached when the temperature is within a temperature range. The temperature range may be fixed or variable depending on various parameters such as, for example, the interval at which the temperature of the workpiece is determined, the characteristics of the workpiece, etc. 
     In block  516 , the control circuitry  105  disables the heating device  110  to stop heating the workpiece  130  when the highest temperature selected current temperature T S  from any of the various sensors  120  indicates that the workpiece  130  has reached the control temperature T C  or is at substantially the control temperature T C . 
     In block  518 , the control circuitry  105  monitors the continuing rise in overshoot temperature of the workpiece  130  based on the outputs of the sensors  120 . Once the outputs of the sensors  120  indicate that the temperature of the workpiece  130  has peaked, the temperature overshoot, which is the difference in temperature from the control temperature T C  to the peak temperature, and the overshoot time, which is the time period from when the heating device  110  is disabled to the workpiece  130  reaching its peak temperature, are determined. 
     In block  520 , a temperature ramp rate is determined by, for example, the processor  210  of the control circuitry  105  based on the temperature overshoot and/or the overshoot time for use in heating the workpiece  130  to the target temperature T T . The temperature ramp rate may be a linear ramp or a non-linear ramp. An example of a linear ramp may be, for example, increasing the control temperature T C  for the workpiece  130  by a constant temperature amount per unit time until the target temperature T T  is reached without overshooting beyond an acceptable margin. The control temperature T C  may be increased, for example, periodically. 
     In some other examples, the control circuitry  105  controls the temperature of the heating device  110  periodically such that the temperature of the workpiece reaches substantially the target temperature T T  without overshooting beyond an acceptable margin. “Substantially the target temperature T T ” may be a temperature within a margin to the target temperature T T  that may be pre-determined for a given usage. The margin may depend on various parameters, such as, for example, the type of metal being heated, the type of heating device  110 , etc. Accordingly, “substantially the target temperature T T ” may be set by the processor  210 , by the user using any of the input devices  242 , or via commands received with the communication interface  230 . 
     As examples, the margin for an application may be within 5% of the target temperature T T  in one case, 2% of the target temperature T T  in another case, 1% of the target temperature T T  in another case, etc. Therefore, as the margin may differ for different cases, the specific margins given as examples above do not limit any examples of the disclosure. 
     The heating period used may be variable in some examples of the disclosure while other examples of the disclosure may have a fixed period. That is, the heating period may change while heating the workpiece  130  or the heating period may remain the same for a first workpiece  130  but may be changed for a second workpiece  130 . The heating period may be timed via a software timer in, for example, the operating system  222  or the applications  224 , or a hardware timer that may be a part of, for example, the control circuitry  105 . 
     A single timer may be used for monitoring the temperature of the workpiece  130  and for using the temperature ramp rate in heating the workpiece  130 , or independent timers may be used. The workpiece  130  may be heated to an interim temperature T I  that is raised, for example, periodically based on the temperature ramp rate. 
     In block  522 , the control circuitry  105  enables the heating device  110  to heat the workpiece  130  to the target temperature T T  using the temperature ramp rate. An example of the disclosure may increase a target temperature of the workpiece  130  to an interim temperature T I  periodically until the interim temperature T I  equals the target temperature T T . Accordingly, the heating device  110  can heat the workpiece  130  according to the increasing interim temperature T I  until the target temperature T T  is reached. 
     In block  524 , during heating to the target temperature T T  using the temperature ramp rate, the control circuitry  105  determines whether the current selected temperature T S  decreases, which can indicate a decoupling of the selected control sensor  120  from the workpiece. If there is a decrease in the selected current temperature T S  (block  524 ), control returns to block  502  to restart the characterization process using one or more different sensors as the selected current temperature T S . For example, a user may select a different set of one or more sensors, and/or the one or more sensors may be automatically selected. 
     If there is not a decrease in the selected current temperature TS (block  524 ), in block  526  the control circuitry  105  determines whether the selected current temperature T S  is greater than or equal to the target temperature T T . If the selected current temperature T S  is less than the target temperature T T  (block  526 ), control returns to block  522  to continue to controlling the heating device  110 . 
     When the selected current temperature T S  is greater than or equal to the target temperature T T  (block  526 ), in block  528 , the heating device  110  is disabled. 
     While an example flow diagram is shown in  FIG. 5  for illustrative purposes, it should be understood that various other flow diagrams may also describe other examples of the disclosure. For example, in another example of the disclosure, the blocks  506  and  508  may happen serially in either order rather than in parallel as shown in  FIG. 5 . 
     While the disclosure has described various examples with respect to welding, it should be understood that the disclosure need not be so limited. Rather, the disclosure should be understood to apply to other situations where an item needs to be heated or pre-heated. 
     Disclosed example systems for controlling heating of a workpiece include an interface configured to receive a target temperature (T T ) for the workpiece, a processor, and a control system. The processor is configured to: select a current temperature (T S ) for the workpiece based on monitoring one or more temperature sensors; and set a control temperature (T C ) based on the received target temperature and the selected current temperature (T S ). The control system is configured to control heating of the workpiece via a heating device until the workpiece reaches the control temperature (T C ) as measured by at least one of the one or more temperature sensors, and control the heating device to stop heating the workpiece in response to the workpiece reaching the control temperature (T C ). The processor is further configured to characterize a temperature ramp rate based on a measured temperature overshoot at the workpiece after turning off the heating device, and the control system is configured to control heating of the workpiece to the received target temperature (T T ) by controlling the heating device based on the temperature ramp rate. 
     In some example systems, the processor is configured to set the control temperature (T C ) to a temperature between the selected current temperature and the received target temperature (T T ). In some example systems, the processor is configured to select the current temperature for the workpiece based on a selection of at least one of the one or more temperature sensors via the interface. 
     In some example systems, the processor is configured to: update the characterization of the temperature ramp rate in response to a change in the selected current temperature or a change in the one or more temperature sensors. In some example systems, the heating device is configured to heat the workpiece using induction. Some example systems include a communication device configured to receive the target temperature (T T ) via one or more of user interface, wired communication from another device, and wireless communication from another device. 
     In some example systems, the processor is configured to perform one or both of: monitor the outputs of the one or more temperature sensors at an expiration of a first time timer, and control updating an interim temperature (T I ) based on the temperature ramp rate at an expiration of a second timer, wherein the control system is configured to heat the workpiece to the interim temperature (T I ). In some example systems, the control system is configured to control the heating device based on the received target temperature (T T ), the temperature ramp rate, and feedback based on the outputs of the one or more temperature sensors. 
     In some example systems, the processor is configured to output an alarm or alert in response to detecting at least a threshold reduction in the selected current temperature while the heating device is heating the workpiece. In some example systems, the processor is configured to select the current temperature for the workpiece as a highest temperature measured by the one or more temperature sensors. In some example systems, the one or more temperature sensors include at least one of an armored temperature sensing device, a spot-welded temperature sensing device, a thermocouple, or an infrared temperature sensor. 
     The present methods and systems may be realized in hardware, software, and/or a combination of hardware and software. The present methods and/or systems may be realized in a centralized fashion in at least one computing system, or in a distributed fashion where different elements are spread across several interconnected computing systems. Any kind of computing system or other apparatus adapted for carrying out the methods described herein is suited. A typical combination of hardware and software may include a general-purpose computing system with a program or other code that, when being loaded and executed, controls the computing system such that it carries out the methods described herein. Another typical implementation may comprise one or more application specific integrated circuit or chip. Some implementations may comprise a non-transitory machine-readable (e.g., computer readable) medium (e.g., FLASH memory, optical disk, magnetic storage disk, or the like) having stored thereon one or more lines of code executable by a machine, thereby causing the machine to perform processes as described herein. As used herein, the term “non-transitory machine-readable medium” is defined to include all types of machine readable storage media and to exclude propagating signals. 
     As utilized herein the terms “circuits” and “circuitry” refer to physical electronic components (i.e. hardware) and any software and/or firmware (“code”) which may configure the hardware, be executed by the hardware, and or otherwise be associated with the hardware. As used herein, for example, a particular processor and memory may comprise a first “circuit” when executing a first one or more lines of code and may comprise a second “circuit” when executing a second one or more lines of code. As utilized herein, the term “exemplary” means serving as a non-limiting example, instance, or illustration. As utilized herein, the terms “e.g.” and “for example” set off lists of one or more non-limiting examples, instances, or illustrations. As utilized herein, circuitry is “operable” to perform a function whenever the circuitry comprises the necessary hardware and code (if any is necessary) to perform the function, regardless of whether performance of the function is disabled or not enabled (e.g., by a user-configurable setting, factory trim, etc.). 
     As utilized herein, “and/or” means any one or more of the items in the list joined by “and/or.” As an example, “x and/or y” means any element of the three-element set {(x), (y), (x, y)}. In other words, “x and/or y” means “one or both of x and y.” As another example, “x, y, and/or z” means any element of the seven-element set {(x), (y), (z), (x, y), (x, z), (y, z), (x, y, z)}. In other words, “x, y and/or z” means “one or more of x, y and z.” As utilized herein, “one of x or y” or “one of x and y” is equivalent to any element of the set {(x), (y)}. 
     As utilized herein, the term “exemplary” means serving as a non-limiting example, instance, or illustration. As utilized herein, the terms “e.g.” and “for example” set off lists of one or more non-limiting examples, instances, or illustrations. As utilized herein, circuitry is “operable” to perform a function whenever the circuitry comprises the necessary hardware and code (if any is necessary) to perform the function, regardless of whether performance of the function is disabled or not enabled (e.g., by a user-configurable setting, factory trim, etc.). 
     While the present method and/or system has been described with reference to certain examples and/or aspects, 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 present method and/or system. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present disclosure without departing from its scope. Therefore, the present method and/or system are not limited to the particular examples disclosed. Instead, the present method and/or system will include all implementations falling within the scope of the appended claims, both literally and under the doctrine of equivalents.