Patent Publication Number: US-11045850-B2

Title: Apparatus and methods to increase the efficiency of roll-forming and leveling systems

Description:
RELATED APPLICATIONS 
     This patent claims the benefit of U.S. patent application Ser. No. 14/718,960, filed on May 21, 2015, entitled Apparatus and Methods to Increase the Efficiency of Roll-Forming and Leveling Systems, which claims priority to U.S. patent application Ser. No. 13/267,760, filed on Oct. 6, 2011, granted as U.S. Pat. No. 9,050,638, entitled Apparatus and Methods to Increase the Efficiency of Roll-Forming and Leveling Systems, which claims priority to U.S. Provisional Patent Application Ser. No. 61/390,467, filed on Oct. 6, 2010, entitled Methods and Apparatus to Increase the Efficiency of Roll-Forming Systems, all of which are hereby incorporated herein by reference in their entireties. 
    
    
     FIELD OF THE DISCLOSURE 
     The present disclosure relates generally to roll-forming systems, and more particularly, to apparatus and methods to increase the efficiency of roll-forming and leveling systems. 
     BACKGROUND 
     Roll-forming production systems or processes (e.g., roll forming, leveling, etc.) are typically used to manufacture components such as construction panels, structural beams, garage doors, and/or any other component having a formed profile. The moving material may be, for example, a strip material (e.g., a metal) that is pulled from a roll or coil of the strip material and processed using a roll-forming machine or system, or may be a pre-cut strip material that is cut in predetermined lengths or sizes. 
     Whether a strip material is used in the pre-cut process or post-cut process, the strip material is typically leveled, flattened, or otherwise conditioned prior to entering the roll-forming machine or system to remove or substantially reduce undesirable characteristics of the strip material due to shape defects and internal residual stresses resulting from the manufacturing process of the strip material and/or storing the strip material in a coiled configuration. For example, a material conditioner is often employed to condition the strip material (e.g., a metal) to remove certain undesirable characteristics such as, for example, coil set, crossbow, edgewave and centerbuckle, etc. Levelers are well-known machines that can substantially flatten a strip material (e.g., eliminate shape defects and release the internal residual stresses) as the strip material is pulled from the coil roll. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a side view of an example production system configured to process a moving strip material using an example dual or split drive leveler. 
         FIG. 1B  illustrates a partial enlarged view of the example split drive leveler of  FIG. 1A . 
         FIG. 2  illustrates an example system that may be used to drive the dual or split drive leveler of  FIG. 1A . 
         FIG. 3  is a block diagram of an example apparatus that may be used to implement the example methods described herein. 
         FIGS. 4A and 4B  depict a flow diagram of an example method that may be implemented to control the example dual or split drive leveler of  FIGS. 1A, 1B and 2 . 
         FIG. 5  is a block diagram of an example processor system that may be used to implement the example methods and apparatus described herein. 
         FIG. 6  is an electrical schematic depicting a first drive system that may be used to implement the example dual or split drive leveler of  FIGS. 1A and 2 . 
         FIG. 7  is another electrical schematic depicting a second drive system that may be used to implement the example dual or split drive leveler of  FIGS. 1A and 2 . 
         FIG. 8  is an enlarged portion of the electrical schematic of  FIG. 6 . 
         FIG. 9  is an example system that may be used to drive a roll-forming apparatus. 
         FIG. 10  is a block diagram of an example apparatus that may be used to implement the example methods described herein. 
         FIG. 11  is a flow diagram of an example method that may be implemented to control the example split drive leveler of  FIGS. 1A, 1B and 2  or the roll-forming apparatus of  FIG. 9 . 
         FIG. 12  is a graph illustrating a comparison of an amount of energy consumed by a known roll-forming system and roll-forming systems described herein. 
         FIG. 13  is a graph illustrating example energy costs for a known leveler having a single motor. 
         FIG. 14  is a graph illustrating example energy costs for an example leveler apparatus having a regeneration module described herein. 
     
    
    
     DETAILED DESCRIPTION 
     Roll-forming manufacturing processes are typically used to manufacture components such as construction panels, structural beams, garage doors, and/or any other component having a formed profile. A roll-forming production process may be implemented by using a roll-forming machine having a sequenced plurality of work rolls that receive and form a moving material. Each work roll is typically configured to progressively contour, shape, bend, cut, and/or fold a moving material. Typically, a moving material such as, for example, a strip material (e.g., a metal) is pulled from a roll or coil of the strip material and processed using a roll-forming machine or system or may be a pre-cut strip material that is cut in predetermined lengths or sizes. 
     The strip material is typically leveled, flattened, or otherwise conditioned prior to entering the roll-forming machine of the production or processing system. In a processing production system, the strip material (e.g., a metal) is typically conditioned via a leveler system to remove certain undesirable characteristics such as, for example, coil set, crossbow, edgewave and centerbuckle, etc. due to shape defects and internal residual stresses resulting from the manufacturing process of the strip material and/or storing the strip material in a coiled configuration. To prepare a strip material for use in production when the strip material is removed from a coil, the strip may be conditioned prior to subsequent processing (e.g., stamping, punching, plasma cutting, laser cutting, roll-forming, etc.). Levelers are well-known machines that can substantially flatten a strip material (e.g., eliminate shape defects and release the internal residual stresses) as the strip material is pulled from the coil roll. 
     Conventional levelers and/or roll formers can be driven via a single drive system or a multi-drive system. However, unlike the example methods and systems described herein, single and/or multi-drive systems of conventional levelers and/or roll formers typically use a reference speed to control the drives of the system. For example, a multi-drive system may be controlled by operating the drives (e.g., a first motor and a second motor) at a speed that is substantially equivalent to a line speed of the strip material moving through the roll-forming process. 
     The example methods, apparatus and systems described herein significantly improve the efficiency of a drive system (e.g., conserve energy) of roll-forming process (e.g., leveler machines and/or roll-forming machines) that employ a multi-drive system to process a roll-forming operation. Additionally or alternatively, the example methods, apparatus and systems described herein may regenerate energy during a roll-forming and/or leveling process. 
     In general, the example apparatus, methods and systems described herein employ a torque value or torque vectoring reference (as opposed to a reference speed) to control a multi-drive system. Controlling a multi-drive system with a torque reference as opposed to a speed reference significantly improves the effectiveness of the system by reducing the power consumption of the multi-drive system. For example, torque vectoring uses a torque reference or value of a master drive rather than a speed value as a command reference to a slave drive of the multi-drive system. When multiple drives are controlled by a torque reference or value, the speeds of the motors of the multi-drive system adjust to meet that torque reference. 
     In some examples, a torque output of a master drive may be used as a command reference to cause a slave drive to generate an output torque that is different (e.g., a relatively less) than the output torque of the master drive (i.e., torque mismatching). In some examples, a torque output of a master drive may be used as a command reference to cause a slave drive to generate an output torque that is substantially equal to the output torque of the master drive (i.e., torque matching). 
     For example, using a torque matching application or reference to drive a multi-drive system, as opposed to using a speed reference, significantly increases the efficiency and/or the effectiveness of a roll-forming machine because the effects of mechanical mismatches between the drives of the multi-drive system are substantially reduced or eliminated. In particular, a first motor (e.g., the master drive) of the system does not generate more work to work against another motor (e.g., the slave drive) of the system due to the mechanical mismatches of the process line. Thus, the net effect is less power usage to operate the entire system because significantly less power is being wasted as a result of the mechanical mismatches or losses in the system. Thus, the torque matching application described herein prevents a first drive of the multi-drive system from working against another drive of the multi-drive system. Instead, the drives or motors (e.g., a master drive and/or a slave drive) of the multi-drive system will have a speed mismatch, which is held within an acceptable range. If the speeds of the motors of the multi-drive system are outside of the acceptable range, the motors of the multi-drive system are driven with a matching speed value until the speeds of the motors are within an acceptable range. 
     In some examples, a torque mismatching application is employed such that the torque output will not be evenly distributed among the drives of a multi-drive system. The torque mismatch between two drives, for example, may cause a first drive (e.g., the master drive) to produce more work, which may cause a second drive (e.g., a slave drive) to operate as a brake so that energy is regenerated in the second drive (e.g., the slave drive). The regenerated energy may be used to power or drive the first drive (e.g., the master drive), thereby increasing the overall efficiency of the drive system. 
     In general, during operation, a first drive (e.g., a master drive) of a multi-drive system described herein receives a command to operate at a reference speed value (e.g., a process material line speed). A torque reference of the first drive is measured when the first drive is operating at the reference speed. A second drive (e.g., a slave drive) receives a command to generate a torque output that is measured or based on the torque reference of the first drive. For example, in a torque matching application, the slave drive may receive a command to generate an output torque that is equal to the torque output or reference of the first drive (i.e., a one-to-one ratio). For example, a leveling apparatus and/or a roll-former apparatus of a roll-forming system may be configured to operate via the torque matching application. 
     In contrast, in a torque mismatching application, the slave drive receives a command to generate an output torque that is within approximately one percent and five percent of the torque output or reference of the first drive. For example, the slave drive receives a command to generate an output torque that is between one percent and five percent less than the output torque generated by the master drive. For example, in a leveling apparatus, a plurality of exit rolls may be driven by a master drive and a plurality of entry rolls may be driven by a slave drive, where the torque output generated by the slave drive is relatively less than the torque output generated by the master drive to provide a torque output mismatch between the master drive and the slave drive. In this manner, the master drive imparts a negative rotational torque to the slave drive, where the rotational torque has a magnitude greater than a magnitude of a torque output of the slave drive system. As a result, the torque mismatch (e.g., a greater torque imparted to the exit rolls than the entry rolls) causes the slave drive to produce or regenerate electric energy. This regenerated electric energy may be fed back into the system via, for example, a bus and used by either and/or both of the drives. 
     Additionally or alternatively, the example roll-forming systems described herein may include a feedback system to detect if a speed of the second drive (e.g., the slave drive) is within an acceptable limit or range when the first drive or master drive is operating at a reference speed value and the slave drive is operating at either the torque mismatch value or the torque matching value. For example, if the speed of the second drive (e.g., the slave drive) is within an acceptable speed limit or range when producing a torque output measured or based on the torque output or reference of the first drive (e.g., the master drive), then the system continues to operate the second drive based on the torque reference of the first drive. If the speed of the second drive (e.g., the slave drive) is not within an acceptable speed limit or range when commanded to operate based on the torque reference of the first drive (e.g., the master drive), then the system operates the second drive (e.g., the slave drive) based on a speed reference of the first drive (e.g., the speed of the master drive) (i.e., speed matching). 
       FIG. 1A  is a side view an example production system  10  configured to process a moving strip material  100  using an example dual or split drive leveler system  102  (i.e., the split drive leveler  102 ). In some example implementations, the example production system  10  may be part of a continuously moving strip material manufacturing system, which may include a plurality of subsystems that modify, condition or alter the strip material  100  using processes that, for example, level, flatten, punch, shear, and/or fold the strip material  100 . For example, the strip material  100  may be subsequently processed into a construction panel, a structural beam and/or any other component having a formed profile via a roll forming machine such as, for example, the roll-forming machine  900  of  FIG. 9 . In alternative example implementations, the split drive leveler  102  may be implemented as a standalone system. 
     In the illustrated example, the split drive leveler  102  may be placed between an uncoiler  103  and a subsequent operating unit  104 . The strip material  100  travels from the uncoiler  103 , through the leveler  102 , and to the subsequent operating unit  104  in a direction generally indicated by arrow  106 . The subsequent operating unit  104  may be a continuous material delivery system that transports the strip material  100  from the split drive leveler  102  to a subsequent operating process such as, for example, a punch press, a shear press, a roll former, etc. In other example implementations, sheets precut from, for example, the strip material  100  can be sheet-fed through the leveler  102 . 
     The split drive leveler  102  has an upper frame  105  and a bottom frame  107 . The upper frame  105  includes an upper backup  109  mounted thereon and the bottom frame  107  includes an adjustable backup  111  mounted thereon. The adjustable backup  111  may be adjusted relative to the upper backup  109  via a hydraulic system  113  that includes, for example, hydraulic cylinders  113   a  and  113   b . As shown in  FIG. 1A , the upper backup  109  is non-adjustable and fixed to the upper frame  105 . However, in other example implementations, the upper backup  109  may be adjustable. As most clearly shown in  FIG. 1B , the split drive leveler  102  includes a plurality of work rolls  108  disposed between the upper frame  105  and the bottom frame  107 . In this example, the split drive leveler  102  includes a plurality of backup work rolls  108   a  and a plurality of intermediate work rolls  108   b.    
       FIG. 1B  illustrates the plurality of work rolls  108  of the split drive leveler  102  arranged as a plurality of upper work rolls  110  and lower work rolls  112 . The work rolls  108  can be implemented using steel or any other suitable material. The upper work rolls  110  are offset relative to the lower work rolls  112  so that the strip material  100  is fed through the upper and lower work rolls  110  and  112  in an alternating manner. In the illustrated example, the work rolls  110  and  112  are partitioned into a plurality of entry work rolls  114  and a plurality of exit work rolls  116 . As described in greater detail below, the entry work rolls  114  are driven independent of the exit work rolls  116  and the entry work rolls  114  can be controlled independent of the exit work rolls  116 . In this manner, the exit work rolls  116  can apply relatively more rolling torque to the strip material  100  than the amount of rolling torque applied by the entry work rolls  114 . Additionally or alternatively, the exit work rolls  116  can be operated at a relatively higher speed than the entry work rolls  114 . In other example implementations, the example split drive leveler  102  can be provided with a plurality of idle work rolls  115  that can be positioned between and in line with the entry work rolls  114  and the exit work rolls  116 . The idle work rolls  115  are typically non-driven but can be driven in some implementations. 
     Leveling and/or flattening techniques are implemented based on the manners in which the strip material  100  reacts to stresses imparted thereon (e.g., the amount of load or force applied to the strip material  100 ). For example, the extent to which the structure and/or characteristics of the strip material  100  change is, in part, dependent on the amount of load, force, or stress applied to the strip material  100 . To impart a load, force or stress to the strip material  100 , the work rolls  108  apply a plunge force to the strip material  100  to cause the material  100  to wrap (at least partially) around the work rolls  108 . A work roll plunge can be varied by changing a distance between center axes  117  and of the work rolls  108  via, for example, the adjustable backup  111  and the hydraulic system  113 . For example, a plunge force can be increased by decreasing the distance between the center axes  117  of the respective upper and lower work rolls  110  and  112  along a vertical plane. Similarly, a plunge force can be decreased by increasing the distance between the center axes  117  of the respective upper and lower work rolls  110  and  112  along vertical plane. 
     In the illustrated example, the split drive leveler  102  uses the adjustable backup  111  (i.e., adjustable flights) to increase or decrease the plunge depth between the upper and the lower work rolls  110  and  112 . Specifically, the hydraulic cylinders  113   a  and  113   b  move the bottom backup  111  via adjustable flights to increase or decrease the plunge of the upper and the lower work rolls  110  and  112 . In other example implementations, the plunge of the work rolls  110  and  112  can be adjusted by moving the upper backup  109  with respect to the bottom backup  111  using, for example, motor and screw (e.g., ball screw, jack screw, etc.) configurations. 
     To substantially reduce or eliminate residual stresses, the strip material  100  is stretched beyond an elastic phase to a plastic phase of the strip material  100 . That is, the strip material  100  is stretched so that the plastic region extends through the entire thickness of the strip material  100 . Otherwise, when the plunge force F applied to a portion of the strip material  100  is removed without having stretched portions of it to the plastic phase, the residual stresses remain in those portions of the strip material  100  causing the material  100  to return to its shape prior to the force being applied. In such an instance, the strip material  100  has been flexed but has not been bent. 
     The amount of force required to cause a strip material to change from an elastic condition to a plastic condition is commonly known as yield strength. Yield strengths of metals having the same material formulation are typically the same, while metals with different formulations have different yield strengths. The amount of plunge force F needed to exceed the yield strength of a material can be determined based on the diameters of the work rolls  108 , the horizontal separation between neighboring work rolls  108 , a modulus of elasticity of the material, yield strength of the material(s), a thickness of the material, etc. 
     Referring to  FIGS. 1A and 1B , the plunge of the entry work rolls  114  is set to deform the strip material  100  beyond its yield strength. In the illustrated example, the plunge of the entry work rolls  114  is relatively greater than the plunge of the exit work rolls  116 . In some example implementations, the plunge of the exit work rolls  116  can be set to not deform the strip material  100  by any substantial amount but instead only adjust the shape of the strip material  100  to a flat shape. For example, the plunge of the exit work rolls  116  may be set so that a separation gap between opposing surfaces of the upper and lower work rolls  110  and  112  is substantially equal to the thickness of the strip material  100 . 
     In operation, the split drive leveler  102  receives the strip material  100  from the uncoiler  103  and/or precut sheets can be sheet-fed though the leveler  102 . A user may provide material thickness and yield strength data via, for example, a controller user interface (e.g., a user interface of the controller  302  of  FIG. 3 ) to cause a controller to automatically adjust the work rolls  110  and  112  to a predetermined entry and exit work roll plunge depth corresponding to the particular strip material data provided by the user. For example, a controller may control the hydraulic cylinders  113   a  and  113   b  to adjust the adjustable backup  111  to control deflection and/or tilt position of the work rolls  112  relative to the work rolls  110  to determine the location and manner in which the strip material  100  is conditioned. In this manner, less pressure may be applied to ends of the work rolls  112  so that the centers of the work rolls  112  apply more pressure to the strip material  100  than that applied to the edges. By adjusting the lower backup  111  differently across the width of the lower work rolls  112 , different plunge forces can be applied across the width of the strip material  100  to correct different defects (e.g., coil set, crossbow, edgewave and centerbuckle, etc.) in the strip material  100 . 
     Further, the exit work rolls  116  are driven to provide a greater rolling torque to the strip material  100  than the entry work rolls  114 , thereby causing the exit work rolls  116  to pull or stretch the strip material  100  through the leveler  102  and more effectively condition the strip material  100 . The strip material  100  may be taken away or moved away in a continuous manner from the leveler  102  by the second operating unit  104 . 
     Alternatively, the exit work rolls  116  may be driven to provide a rolling torque to the strip material  100  that is substantially equal to a rolling torque provided to the strip material  100  by the entry work rolls  114 . In this manner, driving the first and second work rolls  114  and  116  at substantially the same torque significantly increases the efficiency of the leveler  102 . 
     When the strip material  100  is moving through the leveler  102 , external factors impart a load on the leveler system  102 . For example, the plunge force provided by the work rolls  108 , thickness of the strip material  100 , yield stress of the strip material  100 , stock wheel brake, friction of the gearing etc., impart or exert a load on the system  10 . The system  10  overcomes this load to move the strip material  10  through the leveler  102 . 
       FIG. 2  illustrates an example drive system  200  to drive the split drive leveler  102  of  FIG. 1A . In the illustrated example, the split drive leveler  102  ( FIG. 1 ) includes a multi-drive system having a first drive system  201  and a second drive system  202 . The first drive system  201  includes a first motor  203  (e.g., a slave motor) to drive the entry work rolls  114  and the second drive system  202  includes a second motor  204  (e.g., a master drive) to drive the exit work rolls  116 . The first motor  203  and/or the second motor  204  may be implemented using any suitable type of motor such as, for example, an AC motor (e.g., a 3-phase induction motor), a variable frequency motor, a D.C. motor, a stepper motor, a servo motor, a hydraulic motor, etc. Although not shown, the drive system  200  and/or the leveler  102  may include one or more additional drive systems or motors (i.e., in addition to drive systems  201  and  202  and motors  203  and  204 ). 
     In the illustrated example, to transfer rotational torque from the motors  203  and  204  to the work rolls  108 , the example drive system  200  is provided with a gearbox  205 . The gearbox  205  includes two input shafts  206   a  and  206   b , each of which is operatively coupled to a respective one of the motors  203  and  204 . The gearbox  205  also includes a plurality of output shafts  208 , each of which is used to operatively couple a respective one of the work rolls  108  to the gearbox  205  via a respective coupling  210  (e.g., a drive shaft, a gear transmission system, etc.). In other example implementations, the couplings  210  can alternatively be used to operatively couple the output shafts  208  of the gearbox  205  to the backup rolls  108   a  of the leveler  102  and/or the intermediate work rolls  108   b  of the leveler  102  which, in turn, drive the work rolls  108 . 
     The output shafts  208  of the gearbox  205  include a first set of output shafts  212   a  and a second set of output shafts  212   b . The first motor  203  drives the first set of output shafts  212   a  and the second motor  204  drives the second set of output shafts  212   b . Specifically, the input shafts  206   a  and  206   b  transfer the output rotational torques and rotational speeds from the motors  203  and  204  to the gearbox  205 , and each of the output shafts  212   a  and  212   b  of the gearbox  205  transmits the output torques and speeds to the work rolls  108  via respective ones of the couplings  210 . In this manner, the output torques and speeds of the motors  203  and  204  can be used to drive the entry work rolls  114  and the exit work rolls  116  at different rolling torques and speeds. 
     Additionally, although one gear box  205  is illustrated, the gear box  205  does not mechanically couple the first motor  203  to the second motor  204 . Instead, the first motor  203  of the first drive system  201  is only mechanically coupled to the second motor  204  of the drive system  202  via the strip material  100  moving between the entry rolls  114  and the exit rolls  116 . 
     In other example implementations, two gearboxes may be used to drive the entry and exit work rolls  114  and  116 . In such example implementations, each gear box has a single input shaft and a single output shaft. In this implementation, each input shaft is driven by a respective one of the motors  203  and  204 , and each output shaft drives its respective set of the work rolls  108  via, for example, a chain drive system, a gear drive system, etc. In yet other example implementations, each work roll  108  can be driven by a separate, respective drive system (e.g., drive systems  201  or  202 ) or motor via, for example, a shaft, an arbor, a spindle, etc., or any other suitable drive. Thus, each work roll of the entry work rolls  114  and each work roll of the exit work rolls  116  may be independently driven by a separate motor, where each separate motor may be driven in direct relation or based on an output parameter of one or more of the other motors as described herein. In yet other examples, the drive systems  201  and  202  may each include a plurality of motors, where one motor of the plurality of motors is a master drive and the other ones of the plurality of motors are slave drives. 
     In the illustrated example of  FIG. 2 , the split drive leveler  102  is provided with torque sensors  213  and  214  to monitor the output torques of the first motor  203  and the second motor  204 , respectively. The torque sensor  213  can be positioned on or coupled to the shaft  206   a  of the first motor  203 , and the torque sensor  214  can be positioned on or coupled to the shaft  206   b  of the second motor  204 . The torque sensors  213  and  214  may be implemented using, for example, rotary strain gauges, torque transducers, encoders, rotary torque sensors, torque meters, etc. In other example implementations, other sensor devices may be used instead of torque sensors to monitor the torques of the first and second motors  203  and  204 . In some example implementations, the torque sensors  213  and  214  can alternatively be positioned on shafts or spindles of the work rolls  108  to monitor the rolling torques of the entry work rolls  114  and the exit work rolls  116 . Alternatively, drive system  201  and/or  202  (e.g., a controller) may receive a signal from directly from the motor&#39;s drive that corresponds to the output torques of the second motor  204  or the first motor  203 . 
     Alternatively or additionally, the split drive leveler  102  can be provided with speed sensors or encoders  215  and/or  216  to monitor the output speeds of the first motor  203  and/or the second motor  204 . The encoders  215  and  216  can be engaged to and/or coupled to the shafts  206   a  and  206   b , respectively. The encoders  215  and  216  may be implemented using, for example, an optical encoder, a magnetic encoder, etc. In yet other example implementations, other sensor devices may be used instead of an encoder to monitor the speeds of the motors  203  and  204  and/or the entry and exit work rolls  114  and  116 . 
     In the illustrated example, the example drive system  200  includes a control system  218  to control the torque and/or speed of the first and/or second motors  203  and  204 . In this example, the control system  218  includes a first controller  219  (e.g., a variable frequency drive) to control the torque and/or speed of the first motor  203  and a second controller  220  (e.g., a variable frequency drive) to control the torque and/or speed of the second motor  204 . The first and second controllers  219  and  220  are communicatively coupled via a common bus  223 . 
     As discussed in greater detail below, the second controller  220  monitors the output torque of the second motor  204  (e.g., the master motor) and commands the second motor  204  to operate at a first command reference such as a reference speed value received by the second controller  220 . The first controller  219  or determines a second command reference based on the first output parameter or output torque of the second motor. The first controller  219  controls or causes the first motor  203  to produce relatively less output torque than the second motor  204  (e.g., a significantly lesser torque compared to the torque output of the second motor  204 ). In other words, the torque outputs of the first and second motors  203  and  204  are controlled to provide different output torques (i.e., a torque mismatch) such that the output torque of the second motor  204  is greater than the output torque of the first motor  203  by a predetermined value or percentage. For example, the first motor  203  can be controlled to produce a first output torque equal to a torque ratio value that is less than one multiplied by the output torque of the second motor  204 . Additionally or alternatively, the control system  218  can control the output speeds of the first and second motors  203  and  204  to control the speeds of the entry work rolls  114  and exit work rolls  116 . For example, the first controller  219  can control the speed of the first motor  203  so that it operates at a speed that is substantially equal to the speed of the second motor  204 , or a speed that is less than the speed of the second motor  204  (e.g., a first speed to second speed ratio value that is less than one or some other speed mismatch ratio or predetermined value). 
     As shown, the first controller  219  is electrically coupled to the second controller  219 . Further, the example control system  218  also includes an energy regeneration module  224  (e.g., implemented via an electric circuit  800  of  FIG. 8 ). 
     During operation, a torque mismatch between the first and second motors  203  and  204 , where the second motor  204  (e.g., the master drive) is controlled to provide a relatively greater torque output than the first motor  203  (e.g., the slave drive), causes the second motor  204  to impart a pulling force or effect on the first motor  203  because the second motor  204  is coupled to the exit rolls  116  and the first motor  203  is coupled to the entry rolls  114 . Due to the torque mismatch between the first motor  203  and the second motor  204 , the second motor  204  may cause the first motor  203  to overhaul and act like a brake. In other words, the second motor  204  provides a pulling effect to the strip material  100  which, in turn, provides a pulling effect on the first motor  203  (via the entry rolls  114 ) because the second motor  204  is operatively coupled to the first motor  203  via the strip material  100  being pulled through the leveler  102 . As a result, the first motor  203  is operated as a generator during braking and the electrical energy output is supplied to an electrical load (e.g., the second motor  204 ) via, for example, the circuit  800  of  FIG. 8 . 
     Such a braking effect may occur during operation because the pulling effect may impart a rotational force or negative torque to the shaft  206   a  of the first motor  203 . In other words, the second motor  204  provides a mechanical source of torque input back into the first motor  203  (or the system  200 ). The magnitude of this negative torque may be greater than a magnitude of positive torque output (or the command torque) of the first motor  203  provided by the current draw of the first motor  203 . In other words, the first controller  219  may command the first motor  203  to provide a command output torque (a positive torque) that is a less than the torque output of the second motor  204  (i.e., the mismatch torque). Thus, the first motor  203  draws a current to provide the command output torque. A difference in this torque provides a mechanical input torque to the shaft  206   a  of the first motor  203 . Thus, this mechanical input torque causes the first motor  203  to operate as a brake when the magnitude of a negative torque on the shaft  206   a  is greater than the magnitude of a command torque that is produced by the first motor  203  based on the electrical current draw. This braking action creates a generator effect that causes the first motor  203  to produce or regenerate electric power. 
     The transfer of energy (e.g., the regenerated electric power) to a load provides the braking effect. The energy regeneration module  224  is electrically coupled to the second drive system  202  via the controllers  219  and  220  to transfer the regenerated current to the second motor  204  and/or the first motor  203 , thereby increasing the efficiency of the drive system  200 . For example, the first drive system  201  regenerates electric energy and includes the energy regeneration module  224  to provide the regenerated electric energy to the second drive system  202 , thereby conserving energy and providing a more efficient system (e.g., a fifteen to fifty percent more efficient system) in addition to improving the effectiveness of leveling the strip material  100  when driving the second motor  204  at a higher output torque than the first motor  201 . 
     Further, driving the exit rolls  116  at a torque that is greater the torque of the entry roll  114  causes the second motor  204  to pull or further stretch the strip material  100  through the leveler  102 . Such stretching of the strip material  100  increases the effectiveness of the leveler  102  to level the strip material  100  by removing a relatively greater amount of residual stresses and/or defects that may be trapped within the strip material  100 . In particular, by maintaining the tension in this manner, the entry work rolls  114  can apply sufficient plunge force against the strip material  100  to stretch the material beyond the elastic phase into the plastic phase, thereby decreasing or eliminating internal stresses of the strip material  100 . Controlling the drive system  200  in this manner enables more effective conditioning (e.g., leveling) of the strip material  100  than many known systems. 
     The load imparted to the second motor  204  may be monitored so that a load imparted on the second motor  204  is not substantially greater than a full-load current rating of the second motor  204 . For example, the load imparted on the second drive motor  204  may be directly proportional to an amount of plunge force exerted on the first and second work rolls  114  and  116 . The rotational torque required to rotate the work rolls  108  is directly proportional to the plunge force of the work rolls  108  because increasing the plunge force increases the frictional forces between the work rolls  108  and the material  100 . Thus, increasing the plunge force, in turn, increases a load on the drive system  200 . 
     To overcome the load resulting from the plunge force, the motor (e.g., the second motor  204 ) produces sufficient mechanical power (e.g., horsepower) to provide an output torque that is greater than the load to rotate the plunged work roll. The greater the plunge of the work rolls  108 , the greater the amount of mechanical power a motor must produce to deform the strip material  100  to its plastic phase. Additionally, other factors contribute to a load that the drive system  200  must overcome. For example, along with plunge force exerted on the strip material  100 , other external factors that contribute to the load of the system  200  may include, for example, stock wheel brake, strip material thickness, friction, mechanical losses, etc. Thus, the drive system  200  overcomes this load to process the strip material  100  through the leveler  102 . 
     The mechanical power generated by a motor is directly proportional to the electrical power consumption of the motor, which can be determined based on the constant voltage applied to the motor and the variable current drawn by the motor in accordance with its mechanical power needs. Accordingly, the output torque of a motor can be controlled by controlling an input electrical current of the motor. Under the same principle, the output torque of a motor can be determined by measuring the electrical current drawn by the motor. 
     To monitor the current draw of the second motor  204 , a current sensor  222  is disposed between a power source (not shown) and the second motor  204  to measure the current of the second motor  204 . In this manner, a load imparted on the second motor  204  can be compared to the measured electrical current drawn by the second motor  204 . For example, to determine whether a load imparted on the second motor  204  is within a desired or acceptable range, the current draw of the second motor  204  can be measured when the second motor  204  is operating at a specific torque and compared to the full load current rating of the second motor  204 . For example, the load exerted on the second motor  204  may be within an acceptable range if the current drawn by the second motor  204  at that particular torque output is within a desired or predetermined percentage (e.g., within 5 percent) of the full load current rating of the second motor  204 . Additionally or alternatively, in other examples, the current draw of the first motor  203  may also be measured to determine the load of the first motor  203 . 
       FIG. 3  is a block diagram of an example apparatus  300  that may be used to implement the example methods described herein. In particular, the example apparatus  300  may be used in connection with and/or may be used to implement the example system  200  of  FIG. 2  or portions thereof to provide a torque output mismatch between the first and second motors  203  and  204  so that the second motor  204  can generate relatively more torque than the first motor  203  (e.g., a second output torque to first output torque ratio value that is greater than one and/or a predetermined value). The example apparatus  300  may also be used to implement a feedback system to adjust the mismatch torque ratio of the first and second motors  203  and  204  if the load on the second motor  204  is not within a predetermined range based on a full-load current rating comparison of the second motor  204 . For example, the feedback system ensures that the second motor  204  does not operate above a specific operating rating (e.g. full-load current rating) of the second motor  204 . Additionally or alternatively, the example apparatus  300  may be used to adjust the output speed of the second motor  204  so that the second motor  204  can operate at a relatively faster speed than the first motor  203  (i.e., a second speed to first speed ratio value that is greater than one and/or a predetermined value). For example, if the torque mismatch ratio between the first and second motors  203  and  204  is outside a desired or predetermined range, then the speeds of the first and second motors  203  and  204  are controlled. For example, the first motor  203  may be controlled to operate at a relatively lower speed than the speed of the second motor  204  or, alternatively, at a speed substantially equal to the speed of the second motor  204 . 
     The example apparatus  300  may be implemented using any desired combination of hardware, firmware, and/or software. For example, one or more integrated circuits, discrete semiconductor components, and/or passive electronic components may be used. Additionally or alternatively, some or all of the blocks of the example apparatus  300 , or parts thereof, may be implemented using instructions, code, and/or other software and/or firmware, etc. stored on a machine accessible or readable medium that, when executed by, for example, a processor system (e.g., the processor system  510  of  FIG. 5 ) perform the operations represented in the flowchart of  FIGS. 4A and 4B . Although the example apparatus  300  is described as having one of each block described below, the example apparatus  300  may be provided with two or more of any block described below. In addition, some blocks may be disabled, omitted, or combined with other blocks. 
     As shown in  FIG. 3 , the example apparatus  300  includes a user input interface  302 , a plunge position adjustor  304 , a plunge position detector  306 , a comparator  308 , a storage interface  310 , a reference speed detector  312 , a first torque sensor interface  314 , a second torque sensor interface  316 , a torque adjustor  318 , a current sensor interface  320 , a first speed sensor interface  322 , a second speed sensor interface  324 , a speed adjustor  326 , a first controller interface  328 , a second controller interface  330 , and a current regeneration module  332 , all of which may be communicatively coupled as shown or in any other suitable manner. 
     The user input interface  302  may be configured to determine strip material characteristics such as, for example, a thickness of the strip material  100 , the type of material (e.g., aluminum, steel, etc.), etc. For example, the user input interface  302  may be implemented using a mechanical and/or electronic graphical user interface via which an operator can input the characteristics of the strip material  100  such as, for example, the type of material, the thickness of the material, the yield strength of the material, etc. 
     The plunge position adjustor  304  may be configured to adjust the plunge position of the work rolls  108 . The plunge position adjustor  304  may be configured to obtain strip material characteristics from the user input interface  302  to set the vertical positions of the work rolls  108 . For example, the plunge position adjustor  304  may retrieve predetermined plunge position values from the storage interface  310  and determine the plunge position of the work rolls  108  based on the strip material input characteristics from the user input interface  302  and corresponding plunge depth values stored in the plunge force data structure. The plunge position adjustor  304  may adjust the upper and lower work rolls  110  and  112  to increase or decrease the amount of plunge between the upper and lower work rolls  110  and  112  via, for example, the hydraulic system  113  ( FIG. 2 ). Additionally or alternatively, an operator can manually select the plunge depth of the work rolls  108  by entering a plunge depth valve via the user input interface  302 . 
     Additionally or alternatively, the plunge position detector  306  may be configured to measure the plunge depth position values of the work rolls  108 . For example, the plunge position detector  306  can measure the vertical position of the work rolls  108  to achieve a particular plunge depth (e.g., the distance between the centers of work rolls  108 ). The plunge position detector  306  can then communicate this value to the comparator  308 . Based on the plunge depth values stored in a look-up table (not shown) in association with the characteristics of the strip material  100  received from the user input interface  302 , the plunge position adjustor  304  adjusts the plunge depth of the work rolls  108 . The plunge depth contributes to an external load imparted on the drive system  200  of  FIG. 2 . 
     The storage interface  310  may be configured to store data values in a memory such as, for example, the system memory  524  and/or the mass storage memory  525  of  FIG. 5 . Additionally, the storage interface  310  may be configured to retrieve data values from the memory (e.g., from the data structure). For example, the storage interface  310  may access the data structure to obtain plunge position values from the memory and communicate the values to the plunge position adjustor  304 . 
     The reference speed detector  312  may be communicatively coupled to an encoder or speed measurement device that measures a reference speed value. For example, the reference speed detector  312  may obtain, retrieve or measure a reference speed based on the speed of the strip material  100  traveling through the leveler  102  (e.g., a line speed). Additionally or alternatively, the reference speed detector  312  receives a reference speed of the strip material  100  from the user interface  302 . Additionally or alternatively, the reference speed detector  312  may be configured to send the reference speed measurement value to the comparator  308 . Additionally or alternatively, the reference speed detector  312  may then send the reference speed measurement value to the second controller interface  330  and the second controller interface  330  may then command the second motor  204  to operate at the reference speed measurement value provided by the reference speed detector  312 . 
     The first torque sensor interface  314  may be communicatively coupled to a torque sensor or torque measurement device such as, for example, the torque sensor  213  of  FIG. 2 . The first torque sensor interface  314  can be configured to obtain the torque value of, for example, the first motor  203  and may periodically read (e.g., retrieve or receive) torque measurement values from the torque sensor  213 . The first torque sensor interface  314  may be configured to then send the torque measurement value to the comparator  308 . Additionally or alternatively, the second torque sensor interface  314  may be configured to send the torque measurement values to the first and/or second controller interfaces  328  and  330 . 
     The second torque sensor interface  316  may be communicatively coupled to a torque sensor or torque measurement device such as, for example, the second torque sensor  214  of  FIG. 2 . The second torque sensor interface  316  can be configured to obtain the torque value of, for example, the second motor  204  and may periodically read torque measurement values from the torque sensor  214 . For example, the second torque sensor interface  316  may be configured to then send the torque measurement values to the comparator  308  when the second motor  204  is operating at the reference speed provided by the reference speed detector  312 . Additionally or alternatively, the second torque sensor interface  316  may be configured to send the torque measurement values to the first and/or second controller interfaces  328  and  330 . 
     The comparator  308  may be configured to perform comparisons based on the torque values received from the first torque sensor interface  314  and the second torque sensor interface  316  to determine if the first motor  203  is operating within a predetermined torque mismatch ratio or value of the measured output torque of the second motor  204  when the second motor  204  is operating at the reference speed provided by the reference speed detector  312 . For example, the comparator  308  may be configured to compare the torque values measured by the first torque sensor interface  314  with the torque values measured by the second torque sensor interface  316  to determine if the first motor  203  is generating a torque output that is within the predetermined torque mismatch ratio or value. For example, the comparator  308  compares the torque measurement values provided by the first and second torque sensor interfaces  314  and  316  to determine if the first motor  203  is operating at relatively less output torque than the second motor  204  (e.g., a second torque output to first torque output ratio value that is greater than one). The comparator  308  may then communicate the results of the comparisons to the torque adjustor  318 . 
     The torque adjustor  318  may be configured to adjust (e.g., increase or decrease) the torque of the first motor  203  based on the comparison results obtained from the comparator  308 . For example, if the comparison results obtained from the comparator  308  indicate that a torque mismatch ratio between the torque measurement value measured by the second torque sensor interface  316  and the torque measurement value measured by the first torque sensor interface  314  is less than or greater than a predetermined torque ratio value (e.g., a torque mismatch ratio value of between greater than one), the torque adjustor  318  can adjust the torque of the first motor  203  until a torque mismatch ratio between the torque measurement value measured by the first torque sensor interface  314  and the torque measurement value measured by the second torque sensor interface  316  is within the predetermined torque ratio value or range. 
     Additionally or alternatively, the current sensor interface  320  may be communicatively coupled to a current sensing device such as, for example, the current sensor  222  of  FIG. 2 . The current sensor interface  320  can be configured to obtain the current draw measurement value of, for example, the second motor  204  and may periodically read (e.g., retrieve or receive) current draw measurement values from the current sensor  222 . The current sensor interface  320  may be configured to then send the current draw measurement value to the comparator  308 . Additionally or alternatively, the current sensor interface  320  may be configured to send the current draw measurement values to the first and/or second controller interfaces  328  and  330 . Additionally or alternatively, the current sensor interface  320  may be configured to send the current draw values to the torque adjustor  318 . 
     The first and/or second controller interfaces  328  and  330  and/or torque adjustor  318  may adjust (e.g., increase or decrease) the torque output values of the first and/or second motors  203  and  204  based on the comparison results obtained from the comparator  308 . For example, if the comparison results obtained by the comparator  308  indicate that the second motor  204  is providing an output torque that is insufficient to drive a load (e.g., a plunge force) required to condition the strip material  100  based on the current draw measurement of the second motor  204 , the torque adjustor  318  may increase the torque output of the second motor  204 . 
     Additionally or alternatively, to protect the second motor  204  from being overworked or overloaded, the first and/or second controller interfaces  328  and  330  and/or torque adjustor  318  may adjust (e.g., decrease) the torque output values of the first and/or second motors  203  and  204  if the results obtained by the comparator  308  indicate that the second motor  204  is providing an output torque that is greater than a desired output torque based on the current draw measurement value of the second motor  204  provided by the current sensor interface  320 . For example, the torque adjustor  318  may decrease the output torque of the first and/or the second motors  203  and  204  until the measured current draw value of the second motor  204  is within a desired range. For example, the comparator  308  may receive current draw measurement values of the second motor  204  from the current sensor interface  320  and compare the current draw measurement values to a full-load current rating of the second motor  204  to determine if the current draw of the second motor  204  is within a desired range (e.g., within a range of 5%) of the full-load current rating of the second motor  204 . 
     Additionally or alternatively, the first speed sensor interface  322  may be communicatively coupled to an encoder or speed measurement device such as, for example, the encoder  215  of  FIG. 2 . The first speed sensor interface  322  can be configured to obtain speed values of the first motor  203  by, for example, reading the speed measurement values from the encoder  215 . The first speed sensor interface  322  may be configured to send the speed values to the comparator  308 . The comparator  308  may be configured to compare the speed values obtained from the first speed sensor interface  322  and the speed values obtained from the second speed sensor interface  324  and communicate the results of the comparisons to the speed adjustor  326 . 
     The second speed sensor interface  324  may be communicatively coupled to an encoder or speed measurement device such as, for example, the encoder  216  of  FIG. 2 . The second speed sensor interface  324  can be configured to obtain speed values of the second motor  204  by, for example, reading measurement values from the encoder  216 . The second speed sensor interface  324  may be configured to send the speed values to the comparator  308 . Additionally or alternatively, the second speed sensor interface  324  may be configured to send the speed values to the first and/or second controller interfaces  328  and  330 . 
     The speed adjustor  326  may be configured to adjust the speed of the first motor  203  so that the first motor  203  operates at a relatively slower speed than the second motor  204  (e.g., a predetermined speed value or percentage). For example, the comparison results obtained from the comparator  308  may indicate that a ratio between the speed measurement value measured by the second speed sensor interface  324  and the speed measurement value measured by the first speed sensor interface  322  is less than or greater than a predetermined speed ratio value. The speed adjustor  326  can then adjust the speed of the first motor  203  based on the comparison results obtained from the comparator  308  until a ratio between the speed measurement value measured by the second speed sensor interface  324  and the speed measurement value measured by the first speed sensor interface  322  is substantially equal to the predetermined speed ratio value (e.g., a first motor  203  to second motor  204  ratio of about 3 percent). 
     Additionally or alternatively, the speed adjustor  326  may be configured to adjust the speed of the first motor  203  so that the first motor  203  operates at a substantially equal speed of the second motor  204  if the comparator  308  determines that the torque mismatch between the first and second motors  203  and  204  is causing the second motor  204  to operate outside of a predetermined range of the full-load current rating of the second motor  204 . 
     The example apparatus  300  is also be provided with the current regeneration module interface  332  that may be implemented via, for example, the example circuit  800  of  FIG. 8 . The current regeneration module interface  332  provides circuitry to transfer the energy regenerated by the first motor  203  to the second motor  204 . 
     Although the example apparatus  300  is shown as having only one comparator  308 , in other example implementations, a plurality of comparators may be used to implement the example apparatus  300 . For example, a first comparator can receive the speed measurement values from the first speed sensor interface  322  and the speed measurement values from the second speed sensor interface  324 . A second comparator can receive the torque measurement values from the first torque sensor interface  314  and compare the values to the torque measurement values received from the second torque sensor interface  316 . 
       FIGS. 4A and 4B  illustrate a flow diagram of an example method that may be used to implement the split drive leveler  102  of  FIG. 1A . In some example implementations, the example method of  FIGS. 4A and 4B  may be implemented using machine readable instructions comprising a program for execution by a processor (e.g., the processor  512  of the example system  510  of  FIG. 5 ). For example, the machine readable instructions may be executed by the control system  218  ( FIG. 6 ) to control the operation of the example drive system  200 . The program may be embodied in software stored on a tangible medium such as a CD-ROM, a floppy disk, a hard drive, a digital versatile disk (DVD), or a memory associated with the processor  512  and/or embodied in firmware and/or dedicated hardware. Although the example program is described with reference to the flow diagram illustrated in  FIGS. 4A and 4B , persons of ordinary skill in the art will readily appreciate that many other methods of implementing the example split drive lever  102  may alternatively be used. For example, the order of execution of the blocks may be changed, and/or some of the blocks described may be changed, eliminated, or combined. 
     For purposes of discussion, the example method of  FIGS. 4A and 4B  is described in connection with the example apparatus  300  of  FIG. 3 . In this manner, each of the example operations of the example method of  FIGS. 4A and 4B  is an example manner of implementing a corresponding one or more operations performed by one or more of the blocks of the example apparatus  300  of  FIG. 3 . 
     Turning in detail to  FIGS. 4A and 4B , initially, the user input interface  302  receives material characteristics information to adjust the plunge depth of the work rolls  108  (block  402 ). The material characteristics can include, for example, the thickness of the material, the type of material, etc. The plunge position adjustor  304  determines the plunge depth of the entry work rolls  114  and the exit work rolls  116  required to process the strip material  100  based on the material characteristics received at block  402 . For example, the plunge position adjustor  304  can retrieve plunge depth values from a look-up table or other data structure having start-up plunge depth settings for different material types based on, for example, material yield strengths. In other example implementations, an operator or other user can manually set the initial plunge depth of the entry work rolls  114  and exit work rolls  116 . The strip material  100  may be continuously fed to the leveler  102  from an uncoiler (e.g., the uncoiler  103  of  FIG. 1A ). During the leveling operation, subsequent operations (e.g., a roll-forming operation) may be performed as the strip material  100  continuously moves through the leveler  102 . 
     After the plunge position adjustor  304  adjusts of the plunge of the work rolls  114  and  116 , the reference speed is obtained, retrieved or determined by the reference speed detector  312 . For example, the reference speed detector  312  measures the speed value of the strip material  100  moving through the leveler  102  and sends the reference speed measurement value to the second controller interface  330  (block  404 ). Additionally or alternatively, the reference speed may be provided via the user interface  302 . The second controller  220  may then command the second motor  204  (e.g., the master drive or motor) to operate at the reference speed value (block  404 ). 
     The second torque sensor interface  316  measures a torque corresponding to the second motor  204  (e.g., the master drive or motor) via, for example, the torque sensor  214  ( FIG. 2 ) when the second motor  204  is operating at the reference speed (block  406 ). 
     In addition, the second speed sensor interface  324  measures a speed value corresponding to the second motor  204  via, for example, the speed sensor  216  ( FIG. 2 ) when the second motor  204  is operating at the reference speed value (block  408 ). 
     A torque mismatch value is determined based on the torque output of the second motor  204  (e.g., the master motor) when the second motor  204  is operating at the reference speed (block  410 ). For example, a mismatch output torque or ratio may be within a predetermined range of the torque output of the second motor  204  when the second motor  204  is operating at the reference speed. Thus, in some examples, the torque mismatch value may be three percent less than the torque output provided by the second motor at block  404 . 
     The first controller  219  then commands the first motor  203  (e.g., the slave drive or motor) to generate an output torque substantially equal to the mismatch torque value (block  412 ). For example, the second torque sensor interface  316  sends the torque measurement value of the second motor  204  to the comparator  308 . The comparator  308  then compares the torque measurement value of the first motor  203  to the torque mismatch ratio (e.g., a second torque to first torque ratio that is greater than one). The first controller  219  can receive the torque mismatch value and drives the first motor  203  (e.g., the slave motor) to generate the torque mismatch value. 
     In other words, the comparator  308  compares the torque measurement value of the first motor  203  to the torque measurement value of the second motor  204 , and the torque adjustor  318  adjusts the first motor  203  to generate relatively less torque (e.g., a predetermined output torque value that is less than the output torque of the second motor  204 ) than the second motor  204  (block  412 ). 
     The first speed sensor interface  322  then measures a speed corresponding to the first motor  203  via, for example, the encoder  215  ( FIG. 2 ). The comparator  308  can compare the speed measurement value of the first motor  203  to the speed measurement value of the second motor  204  to determine if the first motor  203  is within an acceptable speed range or limit when the first motor  203  is operating at the torque mismatch value (block  414 ). If the speed measurement value of the first motor  203  is outside of the speed limit range (e.g., a speed range value less than or greater than the speed measurement value of the second motor  204 ), the speed adjustor  326  can adjust the speed of the first motor  203  to operate at a speed that is substantially similar or equal to the speed measurement of the second motor  204  (block  416 ). The system  400  then returns to block  414  to determine whether the speed of the first motor  203  within an acceptable range of the second motor  204 . 
     If the speed measurement value of the first motor  203  is within acceptable range or limit (block  414 ), the system  400  then determines if the load on the second motor is within a specific range when the first and second motors  203  and  204  are operating at the torque mismatch value (block  418 ). If the load on the second motor  204  is within the specific range, then the drive system continues to operate the first and second motors  203  and  204  at the mismatch torque value and determines whether to continue monitoring the first and second motors  203  and  204  (block  428 ). 
     To determine if the load on the second motor  204  is within a specific or predetermined range, the current sensor interface  320  measures the current draw of the second motor  204  when the first and second motors  203  and  204  are operating at the mismatch torque value. If the comparator  308  determines that the current draw measurement value of the second motor  204  provided by the current sensor  322  is within a predetermined range (e.g., a predetermined percentage) of the full-load current rating of the second motor  204 , then the load on the second motor  204  is within a predetermined range. For example, the second motor  204  is operating within the predetermined range if the current draw of the second motor  204  is within 5% of the full-load current rating of the second motor  204 . 
     If the load on the second drive is outside of the specific or predetermined range, then the controller determines if the load on the second motor  204  is less than the predetermined range (block  420 ). If the load on the second motor  204  is less than the predetermined range, the torque adjustor  318  increases the torque output of the second motor  204  and/or increases the torque mismatch ratio or value between the first and second motors  203  and  204  (block  426 ). 
     If the load on the second motor  204  is greater than the predetermined range, the torque adjustor  318  decreases the torque output of the second motor  204  and/or decreases the torque mismatch value between the first and second motors  203  and  204  (block  424 ). 
     The example method  400  then determines whether it should continue to monitor the torque mismatch process (block  428 ). For example, if the strip material  100  has exited the leveler  102  and no other strip material has been fed into the leveler  102 , then the example method  400  may determine that it should no longer continue monitoring and the example method  400  is ended. Otherwise, control returns to block  402  and the example method  400  continues to monitor and/or adjust the mismatch torque values of the motors  203  and  204  and cause the second motor  204  to maintain a relatively higher output torque than the first motor  203  (e.g., a second output torque to first output torque ratio value greater than one). 
     As discussed above, driving the second motor  204  using relatively more torque than the first motor  203  causes the exit work rolls  116  to pull the strip material  100  through the split drive leveler  102  during the plunge process of the entry work rolls  114 . In this manner, pulling the strip material  100  while it is stretched or elongated by the entry work rolls  114  facilitates further bending of the neutral axis of the strip material  100  toward the wrap angle of the work rolls  108  to cause substantially the entire thickness of the strip material  100  to exceed its yield point and enter a plastic phase resulting in greater deformation of the strip material  100 . In this manner, the example methods and apparatus described herein can be used to produce a relatively flatter or more level strip material  100  by releasing substantially all of the residual stresses trapped in the strip material  100 , or at least release relatively more residual stresses than many known techniques. 
     Further, as discussed above, driving the second motor  204  with relatively greater torque  204  than the first motor  203  during operation may cause the first motor  203  to provide a braking effect and act as a generator, thereby regenerating energy. The regenerated energy is fed back to the second motor  204  by the current regeneration module  332 , thereby increasing the efficiency of the drive system  200 . In some examples, the drive system  200  disclosed herein may be up to fifty percent more efficient that many known levelers. 
       FIG. 5  is a block diagram of an example processor system  510  that may be used to implement the example methods and apparatus described herein. As shown in  FIG. 5 , the processor system  510  includes a processor  512  that is coupled to an interconnection bus  514 . The processor  512  includes a register set or register space  516 , which is depicted in  FIG. 5  as being entirely on-chip, but which could alternatively be located entirely or partially off-chip and directly coupled to the processor  512  via dedicated electrical connections and/or via the interconnection bus  514 . The processor  512  may be any suitable processor, processing unit or microprocessor. Although not shown in  FIG. 5 , the system  510  may be a multi-processor system and, thus, may include one or more additional processors that are identical or similar to the processor  512  and that are communicatively coupled to the interconnection bus  514 . 
     The processor  512  of  FIG. 5  is coupled to a chipset  518 , which includes a memory controller  520  and an input/output (I/O) controller  522 . As is well known, a chipset typically provides I/O and memory management functions as well as a plurality of general purpose and/or special purpose registers, timers, etc. that are accessible or used by one or more processors coupled to the chipset  518 . The memory controller  520  performs functions that enable the processor  512  (or processors if there are multiple processors) to access a system memory  524  and a mass storage memory  525 . 
     The system memory  524  may include any desired type of volatile and/or non-volatile memory such as, for example, static random access memory (SRAM), dynamic random access memory (DRAM), flash memory, read-only memory (ROM), etc. The mass storage memory  525  may include any desired type of mass storage device including hard disk drives, optical drives, tape storage devices, etc. 
     The I/O controller  522  performs functions that enable the processor  512  to communicate with peripheral input/output (I/O) devices  526  and  528  and a network interface  530  via an I/O bus  532 . The I/O devices  526  and  528  may be any desired type of I/O device such as, for example, a keyboard, a video display or monitor, a mouse, etc. The network interface  530  may be, for example, an Ethernet device, an asynchronous transfer mode (ATM) device, an 802.11 device, a DSL modem, a cable modem, a cellular modem, etc. that enables the processor system  510  to communicate with another processor system. 
     While the memory controller  520  and the I/O controller  522  are depicted in  FIG. 5  as separate functional blocks within the chipset  518 , the functions performed by these blocks may be integrated within a single semiconductor circuit or may be implemented using two or more separate integrated circuits. 
       FIGS. 6 and 7  illustrate schematic diagrams  600  and  700  of a drive system that may be used to implement the drive system  200  of  FIG. 2 . In particular, the electrical diagram  600  of  FIG. 6  illustrates an example drive system that may be used to implement the first drive system  201  of  FIG. 2  and the electrical diagram  700  of  FIG. 7  illustrates an example drive system that may be used to implement the second drive system  202  of  FIG. 2 . 
       FIG. 8  illustrates an enlarged portion of the example electrical schematic illustration of  FIG. 6  showing an example electronic circuit  800  that may be used to implement the example current regeneration module  332  of  FIG. 3 or 224  of  FIG. 2 . 
       FIG. 9  is an example roll-forming system  900  that may be used to manufacture components from the strip material  100 . The example roll-former system  900  may be part of, for example, a continuously moving material manufacturing system such as, for example, the system  10  of  FIG. 1A . For example, the continuous material manufacturing system  10  may include the example roll-former system  900 , which may be configured to form a component or perlin such as, for example, a metal beam or girder having any desired profile (e.g., a C-shaped component), a construction panel, structural beam, etc. In other examples, the example roll-forming system  900  may be a stand-alone system. 
     The example roll-forming system  900  includes a first plurality of roll formers  902  and a second plurality of roll formers  904 , which sequentially exert bending forces upon the material  100  so as to deform the material and attain the desired profile of the component or perlin. The roll formers  902  and  904  cooperatively work to fold and/or bend the strip material  100  to form a component or perlin. Each of the roll formers  902  and  904  may include a plurality of forming work rolls (not shown) (e.g., supported by upper and lower arbors) that may be configured to apply bending forces to the strip material  100  at predetermined folding lines as the strip material  100  is driven, moved, and/or translated through the roll formers  902  and  904  in a direction  905 . More specifically, as the material  100  moves through the example roll-former system  900 , each of the roll formers  902  and  904  performs an incremental bending or forming operation on the material  100  to create a desired shape or configuration. A depth, gap or positional relationship of the work rolls may be adjusted to provide or create a desired shape or profile to the material  100  as the material  100  passes through the roll-forming system  900 . For example, each of the work rolls representing a pass, increment bending or forming operation may be adjusted relative to another one of the work rolls based on the material characteristics such as, for example, thickness, bend, flare, hardness, etc. Adjusting the depth or positional relationship of the work rolls may affect the torque requirements of the drive system  906 . 
     In this example, the roll-forming system  900  includes a multi-drive system  906  having a first drive system  908  to drive the roll formers  902  and a second drive system  910  to drive the roll formers  904 . In this example, the first drive system  908  includes a first motor  912  (e.g., a master drive) to drive the roll formers  902  and the second drive system  910  includes a second motor  914  (e.g., a slave drive) to drive the roll formers  904 . The first motor  912  and/or the second motor  914  may be implemented using any suitable type of motor such as, for example, an AC motor (e.g., a 3-phase induction motor), a variable frequency motor, a D.C. motor, a stepper motor, a servo motor, a hydraulic motor, etc. Although not shown, the roll-forming system  900  may include one or more additional motors. For example, the drive system  906  may include a third motor. 
     The first motor  912  and/or the second motor  914  may be operatively coupled to and configured to drive portions of the respective roll formers  902  and  904  via, for example, gears, pulleys, chains, belts, etc. In yet other examples, each work roll of the plurality of roll formers  902  and/or each work roll of the plurality of roll formers  904  may be independently driven by a dedicated drive system such as, for example, the drive systems  908  or  910 . Thus, each work roll of the roll formers  902  and each work roll of the roll formers  904  may be independently driven by a separate motor, where each separate motor may be driven in direct relation or based on an output parameter of one or more of the other motors as described herein. Further, the drive system  906  may include a master drive and a plurality of slave drives. 
     An output shaft  916  of the first motor  912  is operatively coupled to the first plurality of roll formers  902  via, for example, a drive shaft, a gear transmission system, a gear box, etc. An output shaft  918  of the second motor  914  is operatively coupled to the first plurality of roll formers  904  via, for example, a drive shaft, a gear transmission system, a gear box, etc. In particular, the first motor  912  of the first drive system  908  is only mechanically coupled to the second motor  914  of the drive system  910  via the strip material  100  moving between the roll formers  902  and the roll formers  904 . 
     In the illustrated example of  FIG. 9 , the roll-forming system  900  is provided with torque sensors  920  and  922  to monitor the output torques of the first motor  912  and the second motor  914 , respectively. The torque sensor  920  can be positioned on or coupled to the shaft  916  of the first motor  912 , and the torque sensor  922  can be positioned on or coupled to the shaft  918  of the second motor  914 . The torque sensors  920  and  922  may be implemented using, for example, rotary strain gauges, torque transducers, encoders, rotary torque sensors, torque meters, etc. In other example implementations, other sensor devices may be used instead of torque sensors to monitor the torques of the first and second motors  920  and  922 . In some example implementations, the torque sensors  920  and  922  can alternatively be positioned on shafts or spindles of the work rolls of the roll formers  902  and/or  904  to monitor the rolling torques of the work rolls of the roll formers  902  and/or  904 . In some examples, the drive system  906  (e.g., via a controller) can receive a signal from the motor&#39;s drive (e.g., the motors  912  and  914 ) that correlates to the output torque value of each of the motors  912  and/or  914 . Alternatively, drive system  201  and/or  202  (e.g., a controller) may receive a signal from directly from the motor&#39;s drive that corresponds to the output torques of the second motor  204  or the first motor  203 . 
     In yet other example implementations, the roll-forming system  900  can be provided with encoders  924  and/or  926  to monitor the output speeds of the first motor  912  and/or the second motor  914 . The encoders  924  and  926  can be engaged to and/or coupled to the shafts  916  and  918 , respectively. Each of the encoders  924  and  926  may be implemented using, for example, an optical encoder, a magnetic encoder, etc. In yet other example implementations, other sensor devices may be used instead of an encoder to monitor the speeds of the motors  912  and  914  and/or the work rolls of the roll former  902  and/or  904 . 
     In the illustrated example, the example drive system  906  includes a control system  928  to control the torque and/or speed of the first and second motors  912  and  914 . In this example, the control system  218  includes a first controller  930  (e.g., a variable frequency drive) to control the torque and/or speed of the first motor  912  and a second controller  932  (e.g., a variable frequency drive) to control the torque and/or speed of the second motor  914 . The first and second controllers  930  and  932  are communicatively coupled via a common bus  934 . 
     As discussed in greater detail below, the first controller  930  monitors the output torque of the first motor  912  (e.g., the master motor) and commands the first motor  912  to operate at a reference speed value received by the first controller  930 . The second controller  932  controls or commands the second motor  914  to produce a substantially similar output torque as the output torque of the first motor  912  when the first motor  912  is operating at the reference speed (i.e., torque matching). In other words, the torque outputs of the first and second motors  912  and  914  are controlled to provide substantially the same output torque values. As a result, the speed outputs of the first and second motors  912  and  914  may be different when the first and second motors  912  and  914  are generating substantially similar output torque values. In other words, the speed of the first motor  912  may be operating at a speed that is lower than the speed of the second motor  914  based on the load imparted on the first motor  912  when operating the first and second motors  930  and  932  at the matching torque value. 
     Additionally or alternatively, the control system  928  can control the output speeds of the first and second motors  912  and  914  such that both the first and the second motors  912  and  914  operate at substantially the same output speed (e.g., the reference speed value). For example, the control system  928  operates the first and second motors  912  and  914  at the same speeds as the reference speed when the speed output value of the second motor  914  (e.g., the slave drive) is outside of a predetermined speed range or value when the first and second motors  912  and  914  are operating at the torque matching value. For example, the second controller  932  can control the speed of the second motor  914  to operate at a speed that is substantially equal to the speed of the first motor  912 . 
     In operation, as the material  100  moves through the first roll formers  902 , the first motor  912  (or master drive) may require more torque to feed the material  100  until the material  100  is driven to the second roll formers  904 . Once the material moves (e.g., continuously moves) to the second roll formers  904 , the second controller  932  commands the second motor  914  to drive at the output torque of the first motor  912  when the first motor  912  is operating at the reference speed value. When the torque outputs of the first and second motors  912  and  914  are substantially equal, the torque matching causes the torque across the drive system  908  to be substantially evenly distributed among the drive systems  908  and  910 . As a result, the power loss between the first and second drive systems  908  and  910  is substantially reduced or eliminated because the first motor  912  and/or the second motor  914  do not work against each other due to mechanical mismatches in the roll-forming system  900 , thereby significantly reducing the overall power usage of the system  900 . 
     In a conventional roll-forming apparatus or system, operating multiple drive systems or motors at similar or equal speeds may not account for mechanical mismatches or losses between the upstream and downstream roll formers. For example, setting or causing all the drives in a conventional roll-forming apparatus to operate at the same speed may cause the torque output of each of the drives in the system to adjust to meet the particular speed reference. As a result, a torque mismatch in a roll-forming system may cause one motor of the system to produce more work against another motor of the system from opposing sides of the mechanical mismatch. For example, a first motor downstream of a second motor may generate a greater output torque to maintain the speed of the downstream motor at the specified reference speed value. As the strip material  100  is being bent via the forming work rolls of the downstream roll former, a greater load may be imparted on the downstream motor to process the strip material  100  while maintaining the output speed at the set reference speed. An upstream motor may also increase its output torque to resist the downstream motor from pulling the strip material  100  through the upstream roll former with a higher torque or force. 
     Thus, unlike conventional roll-forming systems, the example roll-forming system  900  described herein uses a torque matching technique during operation. The torque matching technique significantly improves the efficiency of the drive system  906  by substantially reducing or accounting for mechanical losses due to mechanical mismatches between the first and second motors  912  and  914 . For example, the first controller  930  may operate the first motor or master drive  912  at a reference speed and measure the torque output of the first motor  912  when the first motor  912  is operating at the reference speed. The second controller  932  may operate the second motor or the slave drive  914  at the measured output torque of the first motor  912  when the first motor  912  is operating at the reference speed. During operation and when the strip material  100  is passing through the roll formers  902  and  904 , both the first motor  912  and the second motor  914  operate at substantially the same torque values. As a result, the torque outputs of the first and second motors  912  and  914  are substantially evenly distributed among all the drives  908  and  910 . The overall power usage of the first and second motors  912  and  914  is reduced because there are no losses of power from the drives  908  and  910  working against each other across mechanical mismatches. Thus, the roll-forming system  900  provides a more efficient drive system  906  compared to a drive system of a conventional roll-forming system. 
       FIG. 10  is a block diagram of an example apparatus  1000  that may be used to implement the example methods described herein. In particular, the example apparatus  1000  may be used in connection with and/or may be used to implement the example system  900  of  FIG. 9  or portions thereof to match a torque output between the first and second motors  912  and  914  so that the second motor  914  can generate a torque output that is substantially equal to the torque output of the first motor  912 . Alternatively, as described in greater detail below, the example apparatus  1000  may be used to implement an example leveler such as, for example, the leveler apparatus  102  of  FIGS. 1A and 1B . The example apparatus  1000  may also be used to implement a feedback system to adjust the speed ratio of the first and second motors  912  and  914 . For example, the feedback system may cause the first and second motors  912  and  914  to operate at a substantially similar speed (speed matching) if the speed of the second motor  914  is not within a predetermined speed range when the first motor  912  is operating at the torque output based on the reference speed input. For example, the feedback system ensures that the second motor  914  does not operate above a specific operating speed range (e.g. within 5% of the reference speed) of the first motor  912  during operation. For example, if the torque matching ratio between the first and second motors  912  and  914  causes the second motor  914  to operate outside a desired or predetermined speed range, then the speeds of the first and second motors  203  and  204  are controlled to be substantially the same (e.g., the speed of the reference speed). 
     The example apparatus  1000  may be implemented using any desired combination of hardware, firmware, and/or software. For example, one or more integrated circuits, discrete semiconductor components, and/or passive electronic components may be used. Additionally or alternatively, some or all of the blocks of the example apparatus  1000 , or parts thereof, may be implemented using instructions, code, and/or other software and/or firmware, etc. stored on a machine accessible medium that, when executed by, for example, a processor system (e.g., the processor system  510  of  FIG. 5 ) perform the operations represented in the flowchart of  FIG. 11 . Although the example apparatus  1000  is described as having one of each block described below, the example apparatus  1000  may be provided with two or more of any block described below. In addition, some blocks may be disabled, omitted, or combined with other blocks. 
     As shown in  FIG. 10 , the example apparatus  1000  includes a user input interface  1002 , a comparator  1004 , a storage interface  1006 , a reference speed detector  1008 , a first torque sensor interface  1010 , a second torque sensor interface  1012 , a torque adjustor  1014 , a first speed sensor interface  1016 , a second speed sensor interface  1018 , a speed adjustor  1020 , a first controller interface  1022 , and a second controller interface  1024 , all of which may be communicatively coupled as shown or in any other suitable manner. 
     The user input interface  1002  may be configured to determine the formed component characteristics or parameters. For example, the formed components are typically manufactured to comply with tolerance values associated with bend angles, lengths of material, distances from one bend to another to form a specific profile (e.g., an L-shaped profile, a C-shaped profile, etc.). For example, the user input interface  1002  may be implemented using a mechanical and/or electronic graphical user interface via which an operator can input the characteristics. The system  1000  may also include work roll position adjustor  1026  to adjust the angle and/or position of the forming work rolls of the roll formers  902  and/or the roll formers  904  based on the characteristics received by the user input interface  1002 . 
     The storage interface  1006  may be configured to store data values in a memory such as, for example, the system memory  524  and/or the mass storage memory  525  of  FIG. 5 . Additionally, the storage interface  1006  may be configured to retrieve data values from the memory (e.g., from the data structure). For example, the storage interface  1006  may access the data structure to obtain forming roll position values from the memory and communicate the values to the work roll position adjustor  1026 . 
     The reference speed detector  1008  may be communicatively coupled to an encoder or speed measurement device that measures a reference speed value. For example, the reference speed detector  1008  may obtain, retrieve or measure a reference speed based on the speed of the strip material  100  traveling through the roll-forming system  900  (e.g., a line speed of the material). Additionally or alternatively, the reference speed detector  1008  may receive a reference speed from the user interface  1002 . Additionally or alternatively, the reference speed detector  1008  may be configured to send the reference speed measurement value to the comparator  1004 . Additionally or alternatively, the reference speed detector  1008  may then send the reference speed value to the first controller interface  1022 , which may then command the first motor  912  to operate at the reference speed measurement value provided by the reference speed detector  1008 . Additionally or alternatively, the reference speed detector  1008  may then send the reference speed value to the second controller interface  1024 , which may then command the second motor  914  to operate at the reference speed measurement value provided by the reference speed detector  1008 . 
     The first torque sensor interface  1010  may be communicatively coupled to a torque sensor or torque measurement device such as, for example, the torque sensor  920  of  FIG. 9 . The first torque sensor interface  1010  can be configured to obtain the torque value of, for example, the first motor or master drive  912  and may periodically read (e.g., retrieve or receive) torque measurement values from the torque sensor  920 . The first torque sensor interface  1010  may be configured to then send the torque measurement value to the comparator  1004 . Additionally or alternatively, the second torque sensor interface  1012  may be configured to send the torque measurement values to the first and/or second controller interfaces  1022  and  1024 . 
     The second torque sensor interface  1012  may be communicatively coupled to a torque sensor or torque measurement device such as, for example, the second torque sensor  922  of  FIG. 9 . The second torque sensor interface  1012  can be configured to obtain the torque value of, for example, the second motor  914  and may periodically read torque measurement values from the torque sensor  922 . For example, the second torque sensor interface  1012  may be configured to then send the torque measurement values to the comparator  1004 . Additionally or alternatively, the second torque sensor interface  1012  may be configured to send the torque measurement values to the first and/or second controller interfaces  1022  and  1024 . 
     The comparator  1004  may be configured to perform comparisons based on the torque values received from the first torque sensor interface  1010  and the second torque sensor interface  1012  to determine if the second motor  914  is operating within a torque matching value. In other words, the comparator  1004  performs comparisons to determine if the second motor  914  is generating a substantially similar output torque as the output torque of the first motor  912  when the first motor  912  is operating at the reference speed provided by the reference speed detector  1008 . For example, the comparator  1004  may be configured to compare the torque values measured by the first torque sensor interface  1010  with the torque values measured by the second torque sensor interface  1012  to determine if the first motor  912  is generating a first motor torque output to a second motor torque output ratio that is substantially one to one. The comparator  1004  may then communicate the results of the comparisons to the torque adjustor  1014 . 
     The first and/or second controller interfaces  1022  and  1024  and/or the torque adjustor  1014  may be configured to adjust (e.g., increase or decrease) the torque of the second motor  914  (e.g., the slave motor) based on the comparison results obtained from the comparator  1004 . For example, if the comparison results obtained from the comparator  1004  indicate that a torque ratio of the torque measurement value of the second torque sensor interface  1012  and the torque measurement value measured by the first torque sensor interface  1010  is less than or greater than a predetermined torque ratio value (e.g., a torque matching ratio of substantially 1:1), the torque adjustor  1014  can adjust (e.g., increase or decrease) the torque of the second motor  914  until a torque ratio between the torque measurement value measured by the first torque sensor interface  1010  and the torque measurement value measured by the second torque sensor interface  1012  is within the predetermined torque ratio value or range (a torque ratio of 1:1). 
     Additionally or alternatively, the first speed sensor interface  1016  may be communicatively coupled to an encoder or speed measurement device such as, for example, the encoder  924  of  FIG. 9 . The first speed sensor interface  1016  can be configured to obtain speed values of the first motor  912  by, for example, reading the speed measurement values from the encoder  924 . The first speed sensor interface  1016  may be configured to send the speed values to the comparator  1004 . The comparator  1004  may be configured to compare the speed values obtained from the first speed sensor interface  1016  and the speed values obtained from the second speed sensor interface  1018  and communicate the comparison results of the comparisons to the speed adjustor  1020 . 
     The second speed sensor interface  1018  may be communicatively coupled to an encoder or speed measurement device such as, for example, the encoder  926  of  FIG. 9 . The second speed sensor interface  1018  can be configured to obtain speed values of the second motor  914  by, for example, reading measurement values from the encoder  926 . The second speed sensor interface  1018  may be configured to send the speed values to the comparator  1004 . Additionally or alternatively, the second speed sensor interface  1018  may be configured to send the speed values to the first and/or second controller interfaces  1022  and  1024 . 
     The speed adjustor  1020  may be configured to adjust the speed of the first motor  912  and/or the speed of the second motor  914  so that the first motor  912  and the second motor  914  operate at about the same or identical speed (e.g., the reference speed value) when the speed of the second motor  914  (e.g., the slave drive) is outside of a predetermined range when the first motor  912  (e.g., the master drive) is operating at the reference speed. For example, if the comparison results obtained from the comparator  1008  indicate that a ratio between the speed measurement value measured by the second speed sensor interface  1018  and the speed measurement value measured by the first speed sensor interface  1020  is less than or greater than a predetermined speed ratio value (e.g., a predetermined ratio value less than or greater than the speed of the master drive or first motor  912 ), the speed adjustor  1020  can adjust the speed of the second motor  914  (e.g., the slave drive) based on the comparison results obtained from the comparator  1004  until a ratio between the speed measurement value measured by the second speed sensor interface  1018  and the speed measurement value measured by the first speed sensor interface  1020  is substantially equal to the reference speed. 
     Additionally or alternatively, the speed adjustor  1020  may be configured to adjust the speed of the first motor  912  so that the first motor  912  operates at a speed substantially equal to the speed of the second motor  914  if the comparator  10048  determines that the torque matching between the first and second motors  912  and  914  is causing the second motor  914  to operate outside of a predetermined speed range. For example, if the comparator  1004  determines that the speed measurement value measured by the second speed sensor interface  1018  is greater or lower than the speed measurement value measured by the first speed interface  1016  by a factor of, for example, between 1 percent and 5 percent greater than or less than the speed of the first motor  912 , the second controller  932  may command the second motor  914  to operate at the reference speed of the first motor  912  provided by the first speed sensor interface  1016 . 
     Although the example apparatus  1000  is shown as having only one comparator  1004 , in other example implementations, a plurality of comparators may be used to implement the example apparatus  1000 . For example, a first comparator can receive the speed measurement values from the first speed sensor interface  1016  and the speed measurement values from the second speed sensor interface  1018 . A second comparator can receive the torque measurement values from the first torque sensor interface  1010  and compare the values to the torque measurement values received from the second torque sensor interface  1012 . 
       FIG. 11  illustrates a flow diagram  1100  of an example method that may be used to implement the roll-forming system  900  of  FIG. 9 . In some example implementations, the example method of  FIG. 11  may be implemented using machine readable instructions comprising a program for execution by a processor (e.g., the processor  512  of the example system  510  of  FIG. 5 ). For example, the machine readable instructions may be executed by the control system  918  ( FIG. 9 ) to control the operation of the example drive system  906 . The program may be embodied in software stored on a tangible medium such as a CD-ROM, a floppy disk, a hard drive, a digital versatile disk (DVD), or a memory associated with the processor  512  and/or embodied in firmware and/or dedicated hardware. Although the example program is described with reference to the flow diagram illustrated in  FIG. 11 , persons of ordinary skill in the art will readily appreciate that many other methods of implementing the example roll-forming system  900  may alternatively be used. For example, the order of execution of the blocks may be changed, and/or some of the blocks described may be changed, eliminated, or combined. 
     For purposes of discussion, the example method of  FIG. 11  is described in connection with the example apparatus  1000  of  FIG. 10 . In this manner, each of the example operations of the example method of  FIG. 11  is an example manner of implementing a corresponding one or more operations performed by one or more of the blocks of the example apparatus  1000  of  FIG. 10 . 
     Turning in detail to  FIG. 11 , the method  1100  obtains a reference speed value (block  1102 ). For example, the reference speed interface  1008  measures, obtains or retrieves the speed value of the strip material  100  moving through the roll-forming system  900  and sends the reference speed measurement value to the first controller interface  1022 . Additionally or alternatively, the reference speed may be provided to the first controller interface  1022  via the user interface  1002 . 
     The first controller  220  may command the first motor or master drive  912  to operate at the reference speed value (block  1104 ). When the first motor  912  is operating at the reference speed value, the torque output of the first motor  912  is measured (block  1106 ). For example, the torque output of the first motor  912  may be measured by the torque sensor  920 . The first torque sensor interface  1010  may receive this torque measurement value and communicate or send the torque measurement value to the second controller interface  1024  and/or the first controller interface  1022 . 
     When the first motor  912  (e.g., the master drive) is operating at the reference speed, the speed sensor  924  measures the speed output of the first motor  912  and communicates this speed output value to the first speed sensor interface  1016  (block  1108 ). The first speed sensor interface  1016  may store this value via the storage interface  1006 , and/or send it to the comparator  1004 , the first controller interface  1022  and/or the second controller interface  1024 . 
     The second controller  932  then commands the second motor or slave drive  914  to generate an output torque substantially equal to the torque value of the first motor  912  (block  1110 ). In other words, the method  1100  provides a torque matching value so that the second motor or slave drive  914  operates at substantially similar torque output as the first motor or master drive  912 . For example, the first torque interface  1010  sends the torque measurement value of the first motor  912  (e.g., the master drive) to the comparator  1004  and the second torque interface  1012  sends the torque measurement value of the second motor  914  (e.g., the slave drive) to the comparator  1004 . The comparator  1004  compares the torque measurement value of the first motor  912  to the torque measurement value of the second motor  914  and sends a signal to the first and/or second controller interfaces  1022  and  1024  and/or the torque adjustor  1014  to adjust the output torque of the second motor  914  until the comparator  1004  determines that the second motor  914  is generating the same torque output as the first motor  912  (block  1110 ). 
     Additionally or alternatively, the first speed sensor interface  1016  can measure a speed corresponding to the second motor  914  (e.g., the master drive) via, for example, the encoder  926  ( FIG. 9 ). The comparator  1004  can compare the speed measurement value of the second motor  914  (e.g., the slave drive) to the speed measurement value of the first motor  912  to determine if the speed of the second motor  914  is within an acceptable speed range or limit of the speed of the first motor  912  when the first motor and second motors  912  and  914  are operating at the torque matching value (block  1112 ). 
     If the speed measurement value of the second motor  203  is outside of the speed limit range (e.g., a predetermined range greater than or less than the speed measurement value of the first motor or master drive  912 ), then speed adjustor  1020  can adjust the speed of the second motor  914  to operate at a substantially similar or equal speed as the speed measurement value of the first motor  912  (block  1114 ). The method  1100  then returns to block  1112  to determine whether the speed of the second motor  914  is within an acceptable range of the speed of the first motor  912 . 
     If the speed measurement value of the second motor  912  is within the acceptable range or limit (block  1112 ), the method  1100  then continues to operate the first and second motors  912  and  914  at the torque matching value (block  1116 ). 
     The method  1100  then determines whether to continue monitoring the first and second motors  912  and  914  (block  1118 ). For example, if the strip material  100  has exited the roll-forming system  900  and no other strip material  100  has been fed into the roll-forming system  900 , then the example method  1100  may determine that it should no longer continue monitoring and the example process is ended. Otherwise, control returns to block  1106  and the example method  1100  continues to monitor and/or operate the torque matching values of the motors  912  and  914  and cause the second motor  914  to maintain a relatively similar output torque compared to the first motor  912 . 
     Alternatively, the example apparatus  1000  of  FIG. 10  and the example method  1100  of  FIG. 11  may be used to implement an example leveler apparatus such as, for example, the leveler  102  of  FIGS. 1A and 1B . For example, the leveler  102  may be configured to provide a torque matching application based on the example apparatus  1000  and the example method  1100  of  FIGS. 10 and 11  instead of the torque mismatching application provided by the example apparatus  300  of  FIG. 3  and the example method  400  of  FIG. 4 . In other words, the first motor  203  of the example leveler  102  may be configured to provide an output torque that is substantially similar to an output torque provided by the second motor  204 . 
     For example, the controller  220  may obtain a reference speed value (block  1102 ) and drive the second motor  204  the reference speed after the plunge depth of the work rolls  114  and  116  has been set or adjusted (block  1104 ). The torque sensor  214  may measure the output torque of the second motor  204  when the second motor  204  operates at the reference speed (block  1106 ). The speed sensor  216  may measure the speed output of the second motor  204  (block  1108 ). The controller  219  may then receive a command reference or torque output of the second motor  204 . The controller  219  commands or drives the first motor  203  (e.g., the slave drive) at the torque output value of the second motor  204  (block  1110 ). If the speed of the first motor  203  provided or measured by the speed sensor  215  is within a predetermined limit (block  1112 ), then the controller  219  continues to drive or operate the first motor  203  at the same output torque value of the second motor  204  (block  1116 ). If the speed of the first motor  203  is not within the predetermined limit at block  1112 , then the controller  219  adjusts the speed of the first motor  203  to the speed of the second motor  204  and the system  400  returns to block  1112  (block  1114 ). 
     Operating or driving the first and second motors  203  and  204  at substantially the same torque significantly increases the efficiency of the leveler  102  when compared to conventional levelers having only one motor or multi-motors that are independently driven at the same speed reference. 
       FIG. 12  is a graph illustrating a comparison of an amount of energy consumed by a known production system  1202 , a production system  1204  described herein having a split-drive system and a production system  1206  described herein having a split-drive system and a regeneration module (e.g., the leveler  102 ). Referring to  FIG. 12 , each example graph  1208 ,  1210  and  1212  represents an amount of Pounds Processed per Kilowatt Hour (“KWH”) that was collected from the respective leveler apparatus  1202 ,  1204  and  1206 . The pounds of steel processed per kilowatt hour may be determined by dividing the total weight of steel processed by the total kilowatt hours consumed as a result of processing (e.g., leveling) that steel. For example, a kilowatt hour meter was operatively coupled to each of the different leveler apparatus  1202 ,  1204  and  1206  to determine the kilowatt hours and the total amount of steel processed was weighed. 
     The first leveler apparatus  1202  is a conventional leveler apparatus having a single drive or motor and produced 1366 lbs/KWH. The second leveler apparatus  1204  is a split-drive leveler apparatus such as, for example, the split-drive leveler  102  of  FIG. 1A  without having a regeneration module such as the regeneration module  224  of  FIG. 2 . The second leveler apparatus  1204  produced approximately 2069 lbs/KWH, a savings of approximately 34% compared to the leveler  1202 . The third leveler apparatus  1206  is a split-drive leveler apparatus such as, for example the split-drive leveler  102  of  FIG. 1A  having a regeneration module such as the regeneration module  224  of  FIG. 2 . Regenerated energy was captured and fed back to the system via a bus to be reused by both motors in the system. The third leveler apparatus produced 4094 lbs/KWH, a savings of approximately 333% compared to the leveler  1202 . Further, although not shown, in a torque matching application, the efficiency and/or cost savings may be greater than that shown in the graph  1206 . 
       FIG. 13  is a graph  1300  illustrating example energy costs for a conventional leveler having a single motor such as, for example, the leveler  1202  of  FIG. 12 . 
       FIG. 14  is a graph  1400  illustrating example energy costs for a split-drive leveler apparatus described herein having a regeneration module such as, for example the leveler  102  of  FIGS. 1A, 1B and 2  and the leveler  1206  of  FIG. 12 . 
     Although certain methods and apparatus have been described herein, the scope of coverage of this patent is not limited thereto. To the contrary, this patent covers all methods, apparatus, and articles of manufacture fairly falling within the scope of the appended claims either literally or under the doctrine of equivalents.