Patent Publication Number: US-2017361394-A1

Title: Systems and methods for pulsed friction and friction stir welding

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Patent Application No. 62/098,212, filed Dec. 30, 2014, entitled “SYSTEMS AND METHODS FOR PULSED FRICTION AND FRICTION STIR WELDING,” which is incorporated by reference herein in its entirety. 
    
    
     BACKGROUND 
     This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present invention, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present invention. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art. 
     A variety of machines may be used to couple components to one another. For example, components may be coupled together via a filler material and/or by melting the components together (e.g., via welding, soldering, or brazing techniques). Unfortunately, existing machines used to join components to one another may be large, complex, and/or costly. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying figures in which like characters represent like parts throughout the figures, wherein: 
         FIG. 1  is a schematic illustration of a friction stir welding system, in accordance with an embodiment of the present disclosure; 
         FIG. 2  is a schematic illustration of a friction welding system, in accordance with an embodiment of the present disclosure; 
         FIG. 3  is a graph showing torque pulses that may be applied by the friction stir welding system of  FIG. 1  or the friction welding system of  FIG. 2 , in accordance with an embodiment of the present disclosure; and 
         FIG. 4  is a flow diagram of a method for joining components via the friction stir welding system of  FIG. 1  or the friction welding system of  FIG. 2 , in accordance with an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS 
     One or more specific embodiments of the present invention will be described below. These described embodiments are only exemplary of the present invention. Additionally, in an effort to provide a concise description of these exemplary embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers&#39; specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure. 
     Friction welding (FW) and friction stir welding (FSW) are solid-state welding techniques used to join components to one another. Such techniques do not melt the components, but rather, use mechanical friction to generate heat and to mechanically join the components to one another. In general, FW joins a moving component to a stationary component by rotating the moving component as the components are urged together. FSW generally utilizes a tool to join adjacent surfaces of separate components. The tool includes a tool head that is rotated and moved laterally across a joint between the adjacent surfaces, and the frictional heat and mechanical forces cause the adjacent surfaces to join to one another. Unfortunately, FW and FSW systems generally apply high continuous torque to effectively join the components to one another. As a result, FW and FSW systems are large, complex, and/or costly. 
     Accordingly, certain embodiments of the present disclosure include a FSW system or a FW system configured to apply pulsed torque to join components to one another. In particular, the FSW system includes a tool having a tool head and a pin that is configured to be placed adjacent to surfaces of the components. The pin applies a pulsed torque (e.g., rotates through separate discrete angles of rotation) as the pin moves along a joint between the surfaces of the components, thereby joining the components to one another. The FW system includes a tool having a rotating tool head (e.g., shaft) configured to support a movable component. The rotating shaft and the movable component attached thereto are positioned adjacent to a stationary component. A pulsed torque rotates the rotating shaft, and, thus, rotates the attached movable component, through separate discrete angles of rotation as the movable component is pressed (e.g., urged) against the stationary component, thereby joining the movable component and the stationary component to one another. Without the disclosed embodiments, FW and FSW systems apply a continuous or generally steady (e.g., having a generally constant magnitude) torque to join components to one another. In order to apply the continuous torque and withstand corresponding reaction forces, the FW and FSW systems utilize large and/or expensive components. In accordance with the disclosed embodiments, applying pulsed torque enables the disclosed FW and FSW systems to effectively join components with smaller, less complex, and/or less expensive parts. In some cases, the FW and FSW systems may be portable (e.g., handheld), enabling such systems to be utilized in a wide variety of applications. 
     With the foregoing in mind,  FIG. 1  illustrates an embodiment of a friction stir welding (FSW) system  10  configured to employ a pulsed torque to join separate components  20  (e.g., components of a valve, such as a ball valve) to one another. As shown, the FSW system  10  includes a FSW tool  21  having a tool head  22  (e.g., a cylindrical rotary tool) having a pin  24  extending from a bottom surface  26  of the tool head  22 . The tool head  22  is configured to rotate, as shown by arrow  28 , and to translate relative to the components  20 , as shown by arrow  30 . As shown, the FSW system  10  includes an actuator  32  that is configured to drive rotation and/or translation of the tool head  22 . The actuator  32  may be any suitable actuator (e.g., an electric motor, air motor, hydraulic drive, combustion engine, or the like) and may be configured to apply a pulsed torque to drive the tool head  22  through multiple discrete angles of rotation, as discussed in more detail below. When placed in contact with adjacent surfaces  34  (e.g., welding surfaces) of the components  20 , such movement of the tool head  22  causes the surfaces  34  to heat and to plastically deform, thereby joining the components  20  to one another. 
     As shown, the FSW system  10  also includes a controller  36 . In certain embodiments, the controller  36  is an electronic controller having electrical circuitry configured to process data from various components of the FSW system  10 , for example. In the illustrated embodiment, the controller  36  includes a processor, such as the illustrated microprocessor  40 , and a memory device  42 . The controller  36  may also include one or more storage devices and/or other suitable components. The processor  40  may be used to execute software, such as software for controlling the actuator  32  to drive rotation of the tool head  22 , and so forth. Moreover, the processor  40  may include multiple microprocessors, one or more “general-purpose” microprocessors, one or more special-purpose microprocessors, and/or one or more application specific integrated circuits (ASICS), or some combination thereof. For example, the processor  40  may include one or more reduced instruction set (RISC) processors. 
     The memory device  42  may include a volatile memory, such as random access memory (RAM), and/or a nonvolatile memory, such as ROM. The memory device  42  may store a variety of information and may be used for various purposes. For example, the memory device  42  may store processor-executable instructions (e.g., firmware or software) for the processor  40  to execute, such as instructions for controlling the actuator  32  and/or the tool head  22 . The storage device(s) (e.g., nonvolatile storage) may include read-only memory (ROM), flash memory, a hard drive, or any other suitable optical, magnetic, or solid-state storage medium, or a combination thereof. The storage device(s) may store data (e.g., torque data, etc.), instructions (e.g., software or firmware for controlling the actuator  32  and/or the tool head  22 , etc.), and any other suitable data. 
     In certain embodiments, the controller  36  is configured to control the actuator  32  to apply a predetermined pulsed torque (e.g., at a predetermined frequency and/or magnitude stored in the memory  42 ). However, in some embodiments, the controller  36  may be configured to adjust the applied pulsed torque based on various factors or inputs. For example, it may be desirable to apply the pulsed torque at one frequency when the components  20  are formed from certain materials, while it may be desirable to apply the pulsed torque at another frequency when the components  20  are formed from different materials. Accordingly, the controller  36  may be configured to receive various inputs (e.g., from a user interface  46  and/or from one or more sensors  48 ) and to control the actuator  32  based on the inputs. For example, the user interface  46  may enable an operator to input various data, such as a material type, and the data may be received at the controller  36 . By way of another example, the one or more sensors  48  may monitor a temperature at the adjacent surfaces  34  of the components  20  and may provide signals indicative of the temperature to the controller  36 . Based on the inputs and/or signals, the controller  36  may then determine and/or select suitable parameters (e.g., frequency and/or magnitude) for the pulsed torque to be applied by the tool head  22  and may send appropriate instructions to the actuator  32  to drive the tool head  22  according to the suitable parameters. In some embodiments, the controller  36  may additionally or alternatively send instructions to the actuator  32 , or to another suitable actuator, to adjust a transverse speed (e.g., in direction  30 ) based on the inputs and/or signals. Thus, the parameters (e.g., frequency and/or magnitude) of the pulsed torque and/or the transverse speed may be set or adjusted based a material composition of one or more of the components  20 , a material composition of the pin  24 , a thickness of the components  20 , a desired penetration depth (e.g., desired depth of a joint between the components  20 ), a desired width of the joint, a width of the pin  24 , a temperature at the adjacent surfaces  34 , or any other suitable factor or combination thereof. In some embodiments, the transverse speed may be controlled by the operator manually moving the portable FSW system  10  transversely, as shown by arrow  30 . In such cases, the one or more sensors  48  may be configured to monitor the transverse speed and provide a signal indicative of the transverse speed to the controller  36 , while the controller  36  may be configured to receive the signal and select or adjust parameters for the pulsed torque based on the transverse speed, for example. 
     In some embodiments, the FSW system  10  may also include a heating element  50  (e.g., ceramic heating element, conductive contact element, fan to blow hot air, or the like), which may be configured to apply heat to the adjacent surfaces  34  of the components  20  to facilitate joining the components  20  to one another. In such cases, the temperature may not melt the components  20  (e.g., the temperature is below the melting point of the material), but rather may facilitate plastic deformation of the components  20  and increase welding efficiency. Heat applied by the heating element  50  may be controlled by the controller  36 . In some cases, the heat applied by the heating element may be controlled based on data, such as the material type, an applied pulsed torque, a transverse speed, and/or the temperature, or any other type of data listed above, received at the controller  36 . 
     As shown, in some embodiments, some or all of the actuator  32 , the controller  36 , the user interface  46 , and/or any other components of the FSW system  10  may be disposed within a housing  52 . For example, the FSW system  10  may be a portable and/or a handheld system, and an operator may grip and/or support the housing  52  and/or a handle  54  extending from the housing  52  as the tool head  22  and the pin  24  rotate to join the components  20  to one another. In some such embodiments, the handle  54 , or other portion of the housing  52 , may include an actuator  55  (e.g., trigger). In some embodiments, the operator may actuate the trigger  55  to initiate the FSW process. Additionally, in some embodiments, some or all of the components of the FSW system  10  may be powered by a battery  56  (e.g., a rechargeable battery), thereby facilitating use of the FSW system  10  in a wide variety of applications. 
       FIG. 2  illustrates an embodiment of a friction welding (FW) system  60  configured to employ a pulsed torque to join a movable component  62  (e.g., a component of a valve, such as a valve stem) and a stationary component  64  (e.g., a component of a valves, such as a valve ball or valve core) to one another. As shown, the FW system  60  includes a tool  65  having a tool head  66  (e.g., a cylindrical rotary tool) configured to support (e.g., via clamps or any suitable removable fastener  67 ) the movable component  62 . The tool head  66  is configured to rotate, as shown by arrow  68 . The FW system  10  includes an actuator, which may be similar to the actuator  32  discussed above with respect to  FIG. 1 , and which is configured to drive rotation of the tool head  66 . As noted above, the actuator  32  may be any suitable actuator (e.g., an electric motor, air motor, hydraulic drive, combustion engine, or the like) and may be configured to apply a pulsed torque to drive the tool head  66  through multiple discrete angles of rotation, as discussed in more detail below. When a welding surface  72  of the movable component  62  is placed in contact with a welding surface  74  of the stationary component  64 , such movement of the tool head  66  causes the surfaces  72 ,  74  to heat and to plastically deform, thereby joining the components  62 ,  64  to one another. 
     As shown, the FW system  60  also includes the controller  36 , the processor  40 , and the memory  42 , and may have some or all of the control features discussed above with respect to  FIG. 1 . As noted above, in certain embodiments, the controller  36  is configured to control the actuator  32  to apply a predetermined pulsed torque (e.g., at a predetermined frequency and/or magnitude). However, in some embodiments, the controller  32  may be configured to adjust the applied pulsed torque based on various factors or inputs. Accordingly, the FW system  60  may include the user interface  46  and/or the one or more sensors  48 . The controller  36  may be configured to receive user inputs (e.g., a material type) from the user interface  46  and/or signals (e.g., signals indicative of a temperature at the welding surfaces  72 ,  74  or the like) from the one or more sensors  48 . The one or more sensors  48  may be positioned in any suitable location to obtain such signals. Based on the inputs and/or signals, the controller  36  may then determine and/or select suitable parameters (e.g., frequency and/or magnitude) for the pulsed torque to be applied by the tool head  66  and may send appropriate instructions to the actuator  32  to drive the tool head  66  according to the suitable parameters to effectively join the components  62 ,  64  to one another. Thus, the parameters (e.g., frequency and/or magnitude) of the pulsed torque may be set or adjusted based a material composition of one or more of the components  62 ,  64 , a desired penetration depth (e.g., desired depth of a joint between the components  62 ,  64 ), a temperature at the welding surfaces  72 ,  74 , or any other suitable factor or combination thereof. 
     Additionally, the FW system  60  may include the heating element  50 , which may be configured to apply heat to the welding surfaces  72 ,  74  of the components  62 ,  64 . In such cases, the temperature may not melt the components  62 ,  64  (e.g., the temperature is below the melting point of the material), but rather may facilitate plastic deformation of the components  62 , 64  and increase welding efficiency. In such cases, heat applied by the heating element  50  may be controlled by the controller  36 . In some cases, the heat applied by the heating element may be controlled based on data, such as the material type, an applied pulsed torque, and/or the temperature, received at the controller  36 . 
     As shown, in some embodiments, some or all of the actuator  32 , the controller  36 , the user interface  46 , and/or any other components of the FW system  60  may be disposed within a housing  78 . For example, the FW system  60  may be a portable and/or a handheld system, and an operator may grip and/or support the housing  78  and/or a handle  77  extending from the housing  78  as the tool head  66  rotates to join the components  62 ,  64  to one another. In some such embodiments, the handle  77 , or other portion of the housing  78 , may include an actuator  79  (e.g., trigger). In some embodiments, the operator may actuate the trigger  79  to initiate the FW process. Additionally, in some embodiments, some or all of the components of the FW system  60  may be powered by a battery  81  (e.g., a rechargeable battery), thereby facilitating use of the FW system  60  in a wide variety of applications. 
       FIG. 3  is a graph showing torque pulses  80  that may be applied by the FSW system  10  of  FIG. 1  or the FW system  60  of  FIG. 2 , in accordance with an embodiment of the present disclosure. As noted above, without the disclosed embodiments, the FW and FSW systems apply a continuous torque to join components to one another. In order to apply the continuous torque and withstand corresponding reaction forces, the FW and FSW systems utilize large and/or expensive parts. In accordance with the disclosed embodiments, applying pulsed torque may enable the disclosed FSW system  10  and FW system  60  to effectively join components with smaller, less complex, and/or less expensive parts. In some cases, the FSW system  10  and/or the FS system  60  may be portable, enabling such systems to be utilized in a wide variety of applications (e.g., repair or assembly of components in the field). 
     Thus, rather than continuous application of a particular torque (e.g., steady torque or maximum torque), the disclosed embodiments apply pulsed torque. Torque pulses  80  generally oscillate between a lower torque  82  and a higher torque  84 . In some embodiments, the lower torque  82  may be zero torque (e.g., approximately zero torque) or a percentage of the higher torque  84  (e.g., approximately 10-90, 20-70, 30-50, 10-50, or 20-40 percent of the higher torque  84 ). In some embodiments, the lower torque  82  may be between approximately 0-10, 1-8, 2-7, or 3-5% of the higher torque  84 . Additionally, the torque pulses  80  may have any suitable pulse frequency. For example, the pulse frequency may be between approximately 10-100, 20-90, 30-80, 40-70, or 50-60 Hertz (Hz). In some embodiments, the pulse frequency may be approximately 10, 20, 30, 40 50, 60, 70, 80, 90, 100 Hz, or more. 
     In the illustrated graph, the torque pulses  80  are generally uniform over time. However, it should be understood that the torque pulses  80  may have variable frequency and/or variable magnitude over time. For example, the frequency and/or the magnitude of the torque pulses  80  may gradually increase or gradually decrease over time. In other embodiments, the torque pulses  80  may follow any suitable pattern (e.g., preprogrammed or continuously adjustable or continuously variable) and have any suitable frequency and/or magnitude over time. As noted above, the controller  36  may control the actuator  32  such that the torque pulses  80  are applied according to a particular set of parameters (e.g., pulse magnitude and/or frequency), which may be pre-programmed, selected or adjusted based on various inputs (e.g., user inputs received via the user interface  46  and/or signals received via the one or more sensors  48 ), and/or set by an operator, for example. 
       FIG. 4  is a flow diagram of a method  100  for joining components via the FSW system  10  of  FIG. 1  or the FW system  60  of  FIG. 2 , in accordance with an embodiment of the present disclosure. The methods include various steps represented by blocks. It should be noted that any of the methods provided herein may be performed as an automated procedure by a system, such as the FSW system  10  or the FW system  60 . Although the flow charts illustrate the steps in a certain sequence, it should be understood that the steps may be performed in any suitable order, certain steps may be carried out simultaneously, and/or certain steps may be omitted, where appropriate. 
     As shown, in step  102 , the tool head  22  of the FSW system  10  is positioned proximate to the adjacent surfaces  34  of the components  20  to facilitate joining the components  20  to one another. In the context of the FW system  60 , the tool head  66  of the FW system  60  is coupled to the movable component  62  and is positioned proximate to the stationary component  64  to facilitate joining the components  62 ,  64  to one another. In step  104 , an input indicative of a material type may be received at the controller  36 . As discussed above, in certain embodiments, various materials may benefit from the use of certain pulsed torque parameters (e.g., amplitude and/or frequency) during FSW or FW procedures. Accordingly, the controller  36  may control the actuator  32  based at least in part on the material type, which may be input by an operator via the user interface  46 , for example. In step  106 , a signal indicative of a temperature at surfaces of the components (e.g., adjacent surfaces  34  of the components  20  or welding surfaces  72 ,  74  of the components  62 ,  64 ) may be received at the controller  36 . As discussed above, the rotational and/or translational movement of the tool head  22 ,  66  may generate heat. It may be desirable to monitor the temperature to ensure that the components  20 ,  62 ,  64  are within a suitable range (e.g., are not approaching a melting point), for example. Such signals indicative of the temperature may enable the controller  36  to adjust the pulsed torque parameters and/or to adjust heat applied by the heating element  50  to facilitate efficient welding and to block melting of the components  20 , for example. 
     In step  108 , the controller  36  may determine appropriate parameters (e.g., amplitude and/or frequency) for the torque pulses  80 . In some embodiments, the controller  36  may determine appropriate parameters for the torque pulses  80  based at least in part on the material type received in step  104  and/or the temperature received in step  106 . In step  110 , the controller  36  controls the actuator  32  to drive the tool head  22 ,  66  according to the determined appropriate parameters. For example, the controller  36  may provide signals instructing the actuator  32  to drive the tool head  22 ,  66  with torque pulses  80  having a particular amplitude and/or frequency. As discussed above, the controller  36  may control other aspects of the welding process based on such inputs or signals. For example, in the context of the FSW system  10 , the controller  36  may provide signals instructing the actuator  32  to drive the tool head  22  at a particular transverse speed (e.g., in direction  30 ) based on the inputs and/or signals. In some embodiments, the controller  36  may control the heating element  50  based on the inputs and/or signals. 
     As discussed above, in some embodiments, the controller  36  may not receive inputs indicative of material type or signals indicative of temperature as set forth in step  102  and step  104 , respectively, and adjust or select the parameters for the torque pulses  80  based on such inputs, but rather may select or access appropriate parameters for the torque pulses  80  based on preprogrammed parameters (e.g., stored in the memory  42 ). For example, the preprogrammed parameters may be based on the type of components being coupled (e.g., various types or characteristics of valves or components thereof being joined together). In such cases, the tool is positioned as set forth in step  102  and the controller  36  controls the actuator  32  to drive the tool head  22 ,  66  according to the preprogrammed parameters. In some such cases, the controller  36  may automatically control other aspects of the welding process based on preprogrammed parameters, which may be stored in the memory device  42 . For example, in the context of the FSW system  10 , the controller  36  may provide signals instructing the actuator  32  to drive the tool head  22  at a particular transverse speed (e.g., in direction  30 ) and/or may control the heating element  50  based on the preprogrammed parameters. In certain embodiments, the controller  36  may enable the operator to select from among a database of multiple preprogrammed parameters, using the user interface  46 , for example, and may control the actuator  32  to drive the tool head  22 ,  66  according to the selected parameters. 
     As discussed above, without the disclosed embodiments, FSW and FW systems apply a continuous torque to join components to one another. In order to apply the continuous torque and withstand corresponding reaction forces, the FSW and FW systems utilize large and/or expensive parts. In accordance with the disclosed embodiments, applying pulsed torque may enable effective joining of components with smaller and/or less expensive parts. In some cases, the FSW and FW systems may be portable, enabling such systems to be utilized in a wide variety of applications. 
     While the invention may be susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and have been described in detail herein. However, it should be understood that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the following appended claims.