Patent Publication Number: US-2021187778-A1

Title: Motorized systems and associated methods for controlling an adjustable dump orifice on a liquid jet cutting system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS INCORPORATED BY REFERENCE 
     The present application claims priority to U.S. Provisional App. No. 62/952,013, titled MOTORIZED METHOD FOR CONTROLLING AN ADJUSTABLE DUMP ORIFICE ON A LIQUID JET CUTTING SYSTEM, which was filed on Dec. 20, 2019, and is incorporated herein by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure is generally related to systems and methods for controlling operating pressures of liquid jet cutting systems and, more particularly, to the operation of dump orifices on liquid jet cutting systems. 
     BACKGROUND 
     In liquid jet cutting systems, manually adjustable dump orifices (ADO) are commonly used to maintain operating pressure of the cutting system when the system is in a specific operational state or transitioning between different operational states. For example, an ADO can dump water to maintain system pressure at a desired level when the cutting head nozzle is closed, when the cutting system is between cuts, etc. Conventional ADOs include a hand knob that the operator/technician manually adjusts to set the ADO at a desired position/state. 
     In practice, some operators find that the hand knob is difficult to access and/or that the ADO adjustment process is tedious. As a result, operators may fail to check and/or manually adjust the ADO as often as necessary, resulting in undesirable spikes and dips in the system pressure during operation which can lead to increased fatigue and premature wear of the high-pressure system components. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-sectional side view of a conventional adjustable dump orifice configured in accordance with the prior art. 
         FIG. 2  is partially schematic view of a liquid jet cutting system having a motorized adjustable dump orifice configured in accordance with some embodiments of the present technology. 
         FIG. 3A  is a cross-sectional side view of the motorized adjustable dump orifice of  FIG. 2 , and  FIG. 3B  is a partially exploded cross-sectional isometric view of the motorized adjustable dump orifice, configured in accordance with some embodiments of the present technology. 
         FIG. 4  is a flow diagram of a routine for automatically operating a motorized adjustable dump orifice in accordance with some embodiments of the present technology. 
     
    
    
     DETAILED DESCRIPTION 
     The following disclosure describes various embodiments of automatically controlled adjustable dump orifices (ADO) for use with liquid jet cutting systems, such as water jet cutting systems. As described in greater detail below, in some embodiments the automatically controlled ADOs disclosed herein include an electric motor that controls the ADO in response to pressure feedback from the liquid jet cutting system. For example, the motor can be operably connected in a closed-loop control system that monitors liquid pressure or pressures within the liquid jet cutting system (e.g., within the cutting head, the pump, etc.) and utilizes this pressure as feedback or input to control the motor and selectively adjust the setting of the ADO to thereby maintain the pressure in the system at a desired level. In some embodiments, the control system compares the pressure in the liquid jet cutting system to the pressure set point of the pump, and if the difference between the pressure in the system and the set point of the pump is greater than a preset threshold, the control system operates the motor on the ADO as necessary to reduce the difference so that it is within the threshold. Additionally, in some embodiments, when a new orifice is installed at the cutting head, the control system can direct the motor to initially adjust the setting of the ADO to an approximate position (e.g., a predetermined and/or theoretically-calculated position for new orifices) and then the control system “fine tunes” the ADO setting via the pressure feedback loop as the liquid jet cutting system comes up to pressure and begins operation. Embodiments of the motorized ADO control systems described herein can reduce the need for operator involvement, provide a reliable solution for controlling system pressures, and reduce overall component fatigue and wear due to pressure spikes/dips. 
       FIG. 1  is a cross-sectional side view of a conventional manually adjusted ADO  100 . The ADO  100  includes a valve housing  110  that contains a dump orifice  114 . The dump orifice  114  receives high-pressure liquid from the cutting system via an inlet  102  when an on/off valve  116  is in an “open” position. Liquid flowing through the dump orifice  114  exits the valve housing  110  via an outlet  104 . The flow of high-pressure liquid through the dump orifice  114  is controlled by the position of a stem  112 , which is in turn controlled by manual adjustment of a hand crank or knob  106 . More specifically, an operator can manually turn the knob  106  in a first direction to advance the stem  112  toward the dump orifice  114 , thereby reducing the cross-sectional flow area downstream of the orifice  114  and increasing the system pressure. Conversely, the operator can rotate the hand knob  106  in the opposite direction to move the stem  112  away from the dump orifice  114 , thereby increasing the cross-sectional flow area and reducing the system pressure. 
     During setup and operation of the liquid jet cutting system, the ADO  100  will typically need frequent manual adjustment to maintain the pressure in the system at a desired level while the system is not cutting. The need for frequent adjustment can be caused by a number of different factors, including changes in size of the stem  112  resulting from thermal expansion and contraction in use, and from wear of the stem  112  over time. The change in size of the stem  112  can affect the flow of high-pressure liquid through the dump orifice  114  and the corresponding system pressure, requiring that the ADO  100  be manually adjusted to maintain the pressure at the desired level. Additionally, the ADO  100  will usually need readjustment when a new cutting nozzle orifice is installed, because of variability in dimensions between different orifices. If the position of the stem  112  is not adjusted as it expands, contracts and/or wears, or when a new orifice is installed, then pressure spikes and dips can occur when the cutting head nozzle switches between operational states (e.g., when transitioning between cuts). These pressure spikes/dips can have adverse effects on the liquid jet cutting system, including increased fatigue and premature wear of high-pressure components, and on the quality of the work product created by the liquid jet cutting system. 
     In practice, however, some operators may find that the hand knob  106  is difficult to access and/or that the ADO adjustment process is tedious. As a result, operators may fail to check and/or adjust the ADO  100  as often as necessary, resulting in spikes and dips in the system pressure during operation which, as noted above, can lead to increased fatigue and premature wear of the high-pressure system components. Additionally, at times the operator may turn the adjustment knob  106  in either too far or too hard, thereby causing the stem  112  to become stuck in its seat and cause a pressure spike during operation, and possibly requiring a subsequent rebuild or replacement of the ADO  100 . 
     Certain details are set forth in the following description and in  FIGS. 2-4  to provide a thorough understanding of various embodiments of the present technology. In other instances, well-known structures, materials, operations and/or systems often associated with liquid jet cutting systems (e.g., water jet cutting systems), electric motors, computer processing systems, etc. are not shown or described in detail in the following disclosure to avoid unnecessarily obscuring the description of the various embodiments of the technology. Those of ordinary skill in the art will recognize, however, that the present technology can be practiced without one or more of the details set forth herein, or with other structures, methods, components, and so forth. 
     The accompanying Figures depict embodiments of the present technology and are not intended to be limiting of its scope. The sizes of various depicted elements are not necessarily drawn to scale, and these various elements may be arbitrarily enlarged to improve legibility. Component details may be abstracted in the Figures to exclude details such as position of components and certain precise connections between such components when such details are unnecessary for a complete understanding of how to make and use the invention. Many of the details, dimensions, angles and other features shown in the Figures are merely illustrative of particular embodiments of the present technology. Accordingly, other embodiments can have other details, dimensions, angles and features without departing from the spirit or scope of the present disclosure. In addition, those of ordinary skill in the art will appreciate that further embodiments of the present technology can be practiced without several of the details described below. In the Figures, identical reference numbers identify identical, or at least generally similar, elements. To facilitate the discussion of any particular element, the most significant digit or digits of any reference number refers to the Figure in which that element is first introduced. For example, element  210  is first introduced and discussed with reference to  FIG. 2 . 
       FIG. 2  is a partially schematic diagram of a liquid jet cutting system  200  having an automatically controlled adjustable dump orifice  220  configured in accordance with embodiments of the present technology. As described in greater detail below, in some embodiments the automatically controlled adjustable dump orifice  220  can be operated by a motor  222  (e.g., an electric motor), and thus may be referred to herein as the “motorized adjustable dump orifice  220 ” or “motorized ADO  220 .” In the illustrated embodiment, the liquid jet cutting system  200  includes a cutting head  202  that receives high-pressure liquid (e.g., high-pressure water) from a pressurizing system (e.g., a pump  208 ) via a high-pressure conduit  206 . The high-pressure liquid flows through an orifice  203  in the cutting head  202  and, in some embodiments, can be mixed with abrasive material to form a high-pressure jet that is emitted from a nozzle  204 . Flow of the high-pressure liquid from the pump  208  to the cutting head  202  can be controlled by a first valve  216   a  which, in some embodiments, can have an “open” or “on” position and a “closed” or “off” position, and hence can be referred to as an “on/off valve”  216   a . In the illustrated embodiment, the high-pressure conduit  206  is also connected in fluid communication to the motorized ADO  220 . Like the cutting head  202 , the flow of high-pressure liquid from the conduit  206  to the motorized ADO  220  is controlled by a second value  216   b  (e.g., a second “on/off valve”). In some embodiments, the high-pressure pump  208  can be a positive displacement pump (e.g., a rotary direct drive pump or a “crankshaft-driven” pump) which are well known in the art. In other embodiments, the pump  208  can be an intensifier pump or other suitable liquid pressurizing devices known in the art that are configured to pressurize liquid (e.g., water) to pressures suitable for liquid jet cutting, shaping, etc. Such pressures can include, for example, pressures greater than or equal to, e.g., 10,000 psi and less than or equal to, e.g., 130,000 psi. For example, in some embodiments the pump  208  can be configured to provide high-pressure liquid for liquid jet cutting at pressures between 20,000-120,000 psi, between 30,000-120,000 psi, between 40,000-120,000 psi, and/or between 50,000-120,000 psi. Although the motorized ADO  220  is schematically illustrated as being separate from the pump  208  in  FIG. 2  for purposes of illustration, in some embodiments the motorized ADO  220  can be positioned, e.g., in the pump housing or otherwise located proximate to the pump  208  and/or operably connected in fluid communication therewith. 
     In the illustrated embodiment, the motorized ADO  220  includes a valve housing  210  that contains an adjustable dump orifice  214 . The flow of high-pressure liquid through the dump orifice  214  is controlled by a dump orifice valve  221  that includes a tapered pin or “stem”  212 . As described in greater detail below with reference to  FIGS. 3A and 3B , the position of the stem  212  is controlled by the motor  222 , which is operably coupled to the valve housing  210  by means of a coupling housing  224  and a corresponding adaptor  226 . By way of example, the motor  222  can be any suitable type of machine (e.g., an electric motor) that converts electrical energy into mechanical energy including, for example, stepper motors, servo motors (e.g., precision servo motors), linear motors, etc. In some embodiments, for example, the motor  222  can be a NEMA 23 stepper motor. In some embodiments, the motor  222  can include an encoder (e.g., a rotary encoder) to, for example, return or move the motor output shaft to an “absolute” or selected position, but in other embodiments an encoder can be omitted. In other embodiments, it is contemplated that the motor  222  can be other types of suitable drivers or drive devices that can move the stem  212  or otherwise control operation of the dump orifice valve  221 . Such devices can include, for example, hydraulically and/or pneumatically powered devices. 
     In the illustrated embodiment, the liquid jet cutting system  200  further includes a controller  230  (shown schematically) operably connected to the pump  208 , the motor  222 , the first and second on/off valves  216   a, b , and one or more pressure sensors  236 . In some embodiments, the pressure sensor  236  can be a potentiometric pressure transducer configured to provide an electronic signal to the controller  230  that is indicative of the operating pressure of the liquid contained in the high-pressure conduit  206 . In other embodiments, other types of pressure sensing devices known in the art can be used to provide pressure information to the controller  230 , including other types of pressure transducers, piezoelectric pressure sensors, strain gauge pressure sensors, electromagnetic pressure sensors, optical pressure sensors, inductive pressure sensors, capacitive pressure sensors, variable reluctance pressure sensors, etc. Although, the pressure sensor  236  is illustrated as being operably connected to the high-pressure conduit  206  and in fluid communication therewith, in other embodiments the pressure sensor  236  and/or other pressure sensors can be mounted to the pump  208  (to, e.g., monitor the pressure at the pump  208 ), to the cutting head  202 , and/or to other portions of the system  200  to monitor and/or determine the pressure of the working liquid and provide a corresponding signal or signals to the controller  230 . Additionally, it will be appreciated that although a single pressure sensor  236  is illustrated in  FIG. 2 , in other embodiments two or more pressure sensors can be used to monitor the pressure of the high-pressure liquid in the cutting system  200 . In some embodiments, the controller  230  can also be operably connected to a user interface of the pump  208 , and/or to a separate user interface (e.g., touchpad, keypad, etc.) for receiving user inputs for controlling operation of the liquid jet cutting system  200 . 
     The controller  230  can include one or more processors  232  and memory  234  that can be programmed with instructions (e.g., non-transitory computer-readable instructions contained on a computer-readable medium) that, when executed by the one or more processors  232 , control operation of the motor  222  and/or other portions of the liquid jet cutting system  200 . For example, in some embodiments, the controller  230  can be operably connected to the motor  222  and the pressure sensor  236  in a closed loop system in which the controller  230  receives feedback (e.g., liquid pressures) from the pressure sensor  236  during operation of the liquid jet cutting system  200 , and then responds by adjusting the setting of the dump orifice valve  221  via the motor  222  as necessary to achieve a desired operating pressure. In some embodiments, the desired operating pressure can be the pressure set point of the pump  208  (i.e., the pressure that the operator sets the pump  208  to operate at). In such embodiments, the controller  230  can compare the liquid pressure in the system as indicated by the pressure sensor  236  to the pressure set point of the pump  208 , and if the liquid pressure in the system differs from the pressure set point by more than a preset threshold amount (e.g. by more than +/−10 psi, +/−100 psi, +/−200 psi, etc.), the controller  230  responds by adjusting the setting of the dump orifice valve  221  via the motor  222  as necessary to bring the pressure within the threshold. After adjusting the dump orifice valve  221 , the controller  230  again receives pressure feedback from the pressure sensor  236  and makes further adjustments to the dump orifice valve  221  if necessary. For example, in some embodiments, when the liquid jet cutting system  200  is cutting a workpiece  218 , the pressure of the high-pressure liquid observed in, e.g., the high-pressure conduit  206  (and/or the cutting head  202  and/or the pump  208 ) should be between about 3,000 to about 5,000 psi higher than the pressure observed in the high-pressure conduit  206  when the cutting head  202  is closed and the motorized ADO  220  is open and dumping liquid, as would occur, for example, when the cutting head  202  is traversing towards the next cut of the workpiece  218 . By use of embodiments of the closed loop feedback system described herein, the controller  230  can control the motor  222  as necessary to adjust the dump orifice valve  221  (e.g., a position of the stem  212  and thereby a size of open cross-sectional area through dump orifice valve  221 ) and maintain the desired operating pressures in the liquid jet cutting system  200  while avoiding detrimental spikes and dips in pressure. 
     Although some embodiments of the present technology monitor the liquid pressure in the system  200  and utilize the pressure as an input to the controller  230  for control of the motor  222 , in other embodiments, the controller  230  can utilize the operating pressure of the pump  208  as feedback or an input for control of the motor  222 . In yet other embodiments, rather than using a direct electrical signal from, e.g., the pressure sensor  236  and/or a pressure sensor on the pump  208  or the cutting head  202 , the controller  230  can receive digital instructions via software for control of the motor  222 . Such instructions can be generated by, e.g., the processor  232  (or another processor associated with the liquid jet cutting system  200 ) in response to a monitored pressure in the liquid jet cutting system  200 . In some embodiments, the controller  230  can be a special purpose computer or data processor that is specifically programmed, configured, or constructed to perform one or more of the operations described in detail herein. While certain functions may be described herein as being performed exclusively by the controller  230 , these functions can also be practiced in distributed environments where functions or modules are shared among separate processing devices. 
     Although certain components and features of the liquid jet cutting system  200  may be omitted from  FIG. 2  for purposes of clarity, it will be understood that the cutting system  200  can include additional components and features of liquid jet cutting systems known in the art and, in particular, water jet cutting systems. For example, the liquid jet cutting system  200  can include a user interface (not shown) for receiving user instructions for operating the cutting system  200 , and one or more actuators (not shown) for controlling movement of the cutting head  202  in accordance with such instructions. Such actuators can be configured to move the cutting head  202  along a processing path (e.g., cutting path) in two or three dimensions and, in at least some cases, to tilt the cutting head  202  relative to the workpiece  218 . The liquid jet cutting system  200  can also include an abrasive-delivery apparatus (also not shown) configured to feed particulate abrasive material from an abrasive material source to the cutting head  202 . The system  200  can further include a system controller operably connected to the user interface, the actuators, the abrasive delivery system, etc. In some embodiments, the system controller can be or can include the controller  230 . In other embodiments, the controller  230  can be a dedicated controller for controlling operation of the motorized ADO  220  and related components, and the system controller can be a separate controller for controlling other operational aspects of the liquid jet cutting system  200 . 
       FIG. 3A  is a cross-sectional side view of the motorized ADO  220 , and  FIG. 3B  is a partially exploded cross-sectional isometric view of the motorized ADO  220  configured in accordance with embodiments of the present technology. Referring first to  FIG. 3A , in the illustrated embodiment, the elongate stem  212  includes a conically-tapered end portion that is movably received in a corresponding conically-tapered seat  312  positioned downstream of the dump orifice  214 . The opposite end portion of the stem  212  abuts or is otherwise operably in contact with a first end portion of a positioning element  308  which is movably received in the adapter  226 . More specifically, in the illustrated embodiment the positioning element  308  is an elongate threaded rod that is threadedly received in a corresponding threaded bore  314  in the adapter  226 . Accordingly, rotation of the positioning element  308  in a first direction (e.g., a clockwise direction) advances the positioning element  308  through the bore  314  and moves the tapered end portion of the stem  212  toward the tapered seat  312  (i.e., from right to left in  FIG. 3A ). Movement of the stem  212  toward the tapered seat  312  reduces the cross-sectional flow area (e.g., the annular cross-sectional area) between the tapered end portion of the stem  212  and the sidewall of the tapered seat  312 , thereby increasing the pressure of high-pressure liquid flowing through the dump orifice  214 . Conversely, rotation of the positioning element  308  in the opposite direction retracts the positioning element  308  through the bore  314  and enables the stem  212  to translate away from the tapered seat  312 , thereby increasing the cross-sectional flow area around the tapered end portion of the stem  212  and reducing the pressure of high-pressure liquid flowing through the dump orifice  214 . 
     In the illustrated embodiment, the adapter  226  includes a first end portion  328   a  and a second end portion  328   b . The first end portion  328   a  is threadedly received in a correspondingly threaded bore  324  in the valve housing  210  and can carry one or more seals  326  to prevent high-pressure liquid from escaping the valve housing  210  around or through the adapter  226 . The second end portion  328   b  of the adapter  226  is threadedly received in a corresponding threaded bore  330  in a first flange  322   a  of the coupling housing  224  to fixedly attach the coupling housing  224  to the valve housing  210 . The coupling housing  224  further includes a second flange  322   b  that is fixedly attached to a corresponding flange  320  of the motor  222  by means of one or more fasteners  321  (e.g.,  150241302 . 1  screws or bolts). In some embodiments, the coupling housing  224  can be made from aluminum. In other embodiments, the coupling housing  224  can be made from other suitable metallic and/or non-metallic materials. 
     Referring next to  FIGS. 3A and 3B  together, in another aspect of the illustrated embodiment the motorized ADO  220  further includes a first gear hub  303  and a second gear hub  307 . The first gear hub  303  is fixedly attached to an output shaft  304  of the motor  222 , and the second gear hub  307  is fixedly attached to the end portion of the positioning element  308  that extends outwardly from the adapter  226 . Both gear hubs  303  and  307  can be made from, e.g., steel, and can include a plurality of gear teeth  302  and  306 , respectively, concentrically arranged around a periphery thereof. The first gear hub  303  on the motor output shaft  304  is operably engaged with the second gear hub  307  on the positioning element  308  by means of a coupling  300 . In the illustrated embodiment, the coupling  300  is a sleeve coupling having a generally cylindrical shape and a plurality of teeth or splines  310  extending inwardly from an interior surface thereof, as best seen in  FIG. 3B . The splines  310  are configured to slidably engage the corresponding teeth  302  and  306  on the gear hubs  303  and  307 , respectively, to operably couple the output shaft of the motor  222  to the positioning element  308 . In some embodiments, the coupling  300  can be a “slide sleeve” coupling made from nylon or other suitably durable materials. In other embodiments, other devices and methods for coupling the motor  222  to the positioning element  308  can be used including, for example, a nylon flex coupling. 
     In some embodiments, the coupling housing  224  can also contain a first alignment/spacer ring  316   a  and a second spacer ring  316   b . The first alignment/spacer ring  316   a  is positioned in an annular groove in the motor flange  320  and is configured to concentrically align the motor  222  (or, more specifically, the motor output shaft  304 ) relative to the coupling housing  224  (or, more specifically, relative to the positioning element  308 ). In some embodiments, the first alignment/spacer ring  316   a  can also be used to prevent the coupling  300  from moving too far in the direction toward the motor  222  during use and, similarly, the second spacer ring  316   b  can be used as a hard stop to prevent the coupling  300  from moving too far in the direction toward the valve housing  210  and potentially sliding off of the first gear hub  303 . In operation, rotational motion of the motor output shaft  304  is transmitted to the positioning element  308  via the first and second gear hubs  303  and  307 , respectively, and the coupling  300 . As described above, the corresponding rotation of the positioning element  308  in clockwise/counterclockwise directions advances/retracts the positioning element  308  through the bore  314  to move the stem  212  toward/away from the tapered seat  312  and thereby increase/decrease the pressure of high-pressure liquid flowing through the dump orifice  214 . 
     Although, in the illustrated embodiment, the motor  222  produces torque which can selectively drive the output shaft  304  in both clockwise and counterclockwise rotation to adjust the setting of the stem  212 , in other embodiments, other types of motors can be used for this purpose. For example, as noted above, in some embodiments a linear electric motor can be used that, instead of producing torque, provides a linear force that can drive, e.g., a corresponding output shaft in fore and aft translational (e.g., linear) motion. By way of example, in such embodiments the positioning element  308  may be an elongate shaft that, rather than rotate in the bore  314 , is instead configured to slide fore and aft in the bore  314 . Further, the linear output shaft of the motor can be coupled to the sliding positioning element so that linear movement of the output shaft toward the valve housing  210  drives the stem  212  toward the seat  312 , while linear movement in the opposite direction moves the stem  212  away from the seat  312 , thereby adjusting the flow through the dump orifice  214  and the corresponding system pressures as described above. Accordingly, it will be appreciated that the present technology is not limited to use with electric motors that provide rotational motion, but can also be used with a wide variety of other suitable drive devices (e.g., other types of electric motors) as disclosed herein. In some embodiments, one or more of the operable connections between components of the motorized ADO  220  may be non-threaded. In further embodiments (e.g., those using a linear electric motor), the motor can be directly attached to the valve housing  210  (e.g., without the coupling housing  224  or the adapter  226 ), and/or the motor output shaft can be directly coupled to the stem  212  (e.g., without the coupling  300 ). 
       FIG. 4  is a flow diagram of a routine  400  for automatically controlling operation of the motorized ADO  220  described in detail above with reference to  FIGS. 2-3B , in accordance with an embodiment of the present technology. All or portions of the routine  400  can be performed by the controller  230  in accordance with computer-readable instructions stored on, e.g., the memory  234 . Although the routine  400  is described below in reference to the liquid jet cutting system  200  described above with reference to  FIG. 2 , it will be appreciated that the routine  400  and/or various portions thereof can be performed with other liquid jet cutting systems having motorized or otherwise automatically controlled ADOs configured in accordance with the present disclosure. 
     Referring to  FIGS. 4 and 2  together, the routine  400  begins with the cutting head valve  216   a  in a closed position, and the ADO valve  216   b  in an open position. In decision block  402 , the routine determines if the cutting head  202  has a new cutting head orifice  203 . For example, in some embodiments determining whether the cutting head  202  has a new orifice  203  can occur manually via input from an operator to the controller  230 . If the cutting head orifice  203  is new, then the routine proceeds to block  404  and sets the motorized ADO  220  at a “start” position. For example, in some embodiments, replacing an old cutting head orifice with a new orifice can change the size of the orifice and, if the other system parameters remain unchanged, the operating pressure of the liquid jet cutting system. For this reason, when a new orifice is installed the controller  230  can direct the motor  222  to move the stem  212  as described above to, e.g., a predetermined “start” position (e.g., an initial or starting position for the stem  212  relative to the seat  312 ). The predetermined “start” position can be a theoretically calculated position that can be determined to set an appropriate pressure for the system based on the size of the replacement orifice. In some embodiments, the motor  222  can include an encoder to facilitate movement of the stem  212  to the “start” position. For example, in some embodiments, the controller  230  can use absolute linear encoder feedback from the motor encoder to set the stem  212  at a desired start position relative to the seat  312 . In another embodiment, the controller  230  can execute a “stem homing” routine whereby the operating current limit for the motor  222  is reduced and the motor is operated to drive the stem  212  into the seat  312  to establish a reference or “home” position. Since the operating current limit for the motor  222  is reduced, the motor is shut off before it can apply excess force to the stem  212  which could damage the stem  212  or the seat  312 . Once the reference position is established, the controller  230  operates the motor  222  to retract the stem  212  to the “start” position (using, e.g., motor encoder feedback). In some embodiments, the foregoing “stem homing” technique may be preferable over other techniques for moving the stem to  212  to a start position because it can compensate for stem erosion and manufacturing variance in stem length, and can also provide a better in situ method of calibrating the reference position. After setting the motorized ADO  220  at the “start” position, the routine  400  proceeds to block  406  and starts the pump  208  in response to operator input (e.g., in response to the operator tuning the pump  208  “on”). Once the liquid jet cutting system  200  begins operating, the controller  230  can “fine tune” the position of the stem  212  as described below to provide a desired operating pressure based on the pressure feedback from, e.g., the pressure sensor  236 . 
     Returning to decision block  402 , if the cutting head orifice has not been replaced, then the routine  400  can proceed directly to block  406  and start the pump  208 . In some embodiments, starting the pump  208  can include the operator manually setting the pump to operate at a desired pressure (e.g., a pressure set point) using a suitable user interface. Once the pump  208  begins operating, it drives high-pressure liquid through the motorized ADO  220  via the high-pressure conduit  206  and the open valve  216   b . In block  408 , the controller  230  receives pressure feedback from the pressure sensor  236  which indicates, e.g., the operating pressure of the high-pressure liquid (e.g., water) in the system. As explained above, in other embodiments the controller  230  can receive the pressure feedback from a corresponding sensor at the pump  208 , the cutting head  202 , and/or another portion of the liquid jet cutting system  200 . In decision block  410 , based on the pressure feedback, the controller  230  determines if the operating pressure is within a specified range of a target pressure. As used herein, the term “target” pressure can refer to a desired operating pressure of the cutting system, (e.g., 30,000 psi, 40,000 psi, etc.) at a particular time. For example, in some embodiments, the target pressure can be the pressure set point of the pump  208 . In other embodiments, such as when the cutting head  202  is transitioning between cuts (and/or the dump valve  221  is open), the target pressure may be less than the pressure set point of the pump  208  (e.g., between about 1,000 to about 6,000 psi less, or about 3,000 to about 5,000 psi less). In some embodiments, the specified range can refer to an acceptable range or preset threshold by which the pressure may vary from the target pressure and not require adjustment of the motorized ADO  220  (e.g., +/−10 psi, +/−100 psi, +/−200 psi, etc.). In other embodiments, the range may be omitted such that the controller  230  controls the setting of the motorized ADO  220  to achieve the target pressure based solely on a comparison of the system pressure to the target pressure. 
     If the operating pressure is not within a specified range of the target pressure, the routine proceeds to decision block  412  and the controller  230  determines if the operating pressure is greater than the specified range of the target pressure. If so, the routine proceeds to block  412  and the controller  230  sends a command to the motor  222  to automatically adjust the motorized ADO  220  to reduce the system pressure as described above. More specifically, with reference to  FIG. 3A , the motor  220  rotates the positioning element  308  by means of the coupling  300  in, e.g., the counterclockwise direction to move the stem  212  outwardly and away from the tapered seat  312  of the dump orifice valve  321 . This increases the cross-sectional area of the corresponding valve opening and consequently reduces the pressure of the high-pressure liquid in the cutting system  200 . Conversely, if the operating pressure is not greater than the specified range of target pressure (i.e. the operating pressure is less than the specified range), then the routine proceeds from decision block  412  to block  414  and the controller  230  sends a command to the motor  222  to adjust the motorized ADO  220  as necessary to increase the pressure of the high-pressure liquid in the liquid jet cutting system  200 . More specifically, again with reference to  FIG. 3A , the controller  230  sends a corresponding control signal to the motor  222  causing the motor to rotate the positioning element  308  in, e.g., the clockwise direction to advance the stem  212  inwardly and towards the tapered seat  312 . This reduces the cross-sectional area of the dump orifice valve  221  and increases the pressure of the high-pressure liquid in the cutting system  200 . 
     After either block  412  or  414 , the routine proceeds to decision block  416  and the controller  230  awaits a signal or instruction (e.g., a software instruction) to start cutting a workpiece, such as the workpiece  218  shown in  FIG. 2 . If the controller  230  has not received an instruction to start cutting, the routine returns to decision block  410  and proceeds as described above. Conversely, when the controller  230  receives a signal to start cutting, the routine proceeds to block  418  and the controller  230  moves the cutting head valve  216   a  to the “open” position and the ADO valve  216   b  to the “closed” position. This causes high-pressure liquid to flow from the pump  208  and through the cutting head nozzle  204  to cut the workpiece  218 , as shown in block  420 . In decision block  422 , the controller  230  determines if it has received a signal or instruction to stop cutting. If not, the routine returns to block  420  and continues cutting the workpiece. Conversely, if the controller  230  receives a signal to stop cutting, the routine proceeds to decision block  424  and determines whether the stop is a temporary stop or a permanent stop. For example, in decision block  424  the controller  230  can determine if the cutting is stopped temporarily while the cutting head  202  transitions from one cut to another cut on the workpiece  218 . Alternatively, the liquid jet cutting system  200  may be finished cutting the workpiece  218 , and thus the signal to the controller  230  will be to stop the cutting process in which case the routine proceeds to block  428  and the controller  230  stops operation of the pump  208 . 
     Conversely, if at decision block  424  the controller  230  determines that the cutting operation has only been temporarily stopped while the cutting head  202  transitions between cuts, then the routine proceeds to block  426  and the controller  230  opens the ADO valve  216   b  while closing the cutting head valve  216   a . This causes the flow of high-pressure liquid through the nozzle  204  to stop, while at the same time causing the high-pressure liquid to flow out of the liquid jet cutting system  200  via the motorized ADO  220  while the pump  208  continues to operate. In this way, the liquid jet cutting system  200  can maintain the high-pressure liquid at a desired pressure during a change of the cutting state and/or a transition of the cutting operation and avoid undesirable pressure spikes/dips as explained above. Moreover, to ensure that the operating pressure of the cutting system  200  is maintained within a desirable range, the routine can return to block  408  and the controller  230  again receives feedback from the pressure sensor  236  indicating the operating pressure of the cutting system  200 . After receiving this input, the controller  230  proceeds through the subsequent steps of the routine as described above to automatically control the motorized ADO  220  and adjust the system operating pressure as necessary to maintain it within a specified range of a desired or “target” pressure. Once the cutting operation has been completed, the routine proceeds to block  428  and stops the pump  208 , and the routine ends. 
     As described above in reference to  FIG. 4 , in some embodiments the motorized ADO  220  is used to control the pressure at the pump  208  automatically while the cutting head nozzle  204  of the liquid jet cutting system  200  is closed. In other embodiments, the motorized ADO  220  can be used as an excess flow valve to set and/or control the pressure through the nozzle  204  of the liquid jet cutting system  200  while the nozzle  204  is open and the machine is cutting. For example, in one such embodiment, the ADO valve  216   b  can be set to the “open” position and the motorized ADO  220  can be adjusted during a “machine reset” stage and left at that setting while the cutting system  200  is cutting. In this manner, leaks in the system and/or wear of the cutting orifice  203  can be detected by monitoring the operation of the motor  222  (e.g., the RPM of the motor output shaft  304 ) by the controller  230  to determine if, e.g., it reaches a value that is above some threshold. By way of example, excessive movement of the motor output shaft  304  to change the setting of the dump orifice valve  221  (e.g., to increase the pressure in the system) can be an indication of leaks and/or wear in the system. In another embodiment, the motorized ADO  220  can set the dump orifice valve  221  at a given position, and then the controller  230  can monitor for leaks and/or orifice wear (e.g., at the cutting head  202 , the pump  208 , the high pressure conduits, the motorized ADO  220 , etc.) by determining if the position and/or variations/movements of the dump orifice valve  221  exceed a preset threshold. 
       FIG. 4  is a representative flow diagram that depicts a process used in some embodiments of the present technology. The flow diagram may not show all the functions associated with the process, but instead provides an understanding of commands and information exchanged under the system. Those of ordinary skill in the art will recognize that some functions or exchange of commands and information may be repeated, varied, omitted, or supplemented, and other (less important) aspects not shown may be readily implemented. Moreover, each of the steps depicted in  FIG. 4  can itself, in some embodiments, include a sequence of operations that need not be described herein. Those of ordinary skill in the art can create source code, microcode, program logic arrays or otherwise implement the disclosed technology based on the flow diagram and the detailed description provided herein. 
     As those of ordinary skill in the art will appreciate, embodiments of the motorized ADOs described herein can reduce the need for operator involvement and provide a more reliable solution for controlling the pressure at the pump  208  ( FIG. 2 ) by automating the procedure of ADO adjustment during operation through use of a pressure feedback control loop. Rather than having a manual hand crank that is reliant on a human operator for adjustment, embodiments of the invention include a control system which monitors system pressures and uses a motor (e.g. an electric stepper motor) to adjust the outlet cross-sectional area of the ADO (by, e.g., turning a threaded rod to thereby move a valve stem back and forth). In some other embodiments, an electric motor with a rotatable output shaft is used to adjust the position of the stem and thereby control and adjust the outlet cross-sectional area of the ADO. In other embodiments, a linear motor is used for this purpose. It is contemplated that electric, hydraulic, pneumatic, and/or other types of motors and other drive devices can be used to adjust the outlet cross-sectional area of the ADO as described herein. 
     Other advantages of embodiments of the systems, devices and methods described herein to control liquid jet cutting system pressures include: a reduction or elimination of operating pressure spikes and dips in the system; increased high-pressure component life; a reduction of part quality issues resulting from an incorrect ADO setting; a reduction in the level of user experience, skill, and training required; and/or a reduction of human involvement and a more automated operation. 
     Another advantage of the systems described herein is that, in some embodiments, the motor does not require an encoder or a similar device to set the ADO in an “initial” or “absolute” position, but instead the controller can use a simple “reset” algorithm to adjust the ADO in response to operating pressure feedback as described above. 
     References throughout the foregoing description to features, advantages, or similar language do not imply that all of the features and advantages that may be realized with the present technology should be or are in any single embodiment of the invention. Rather, language referring to the features and advantages is understood to mean that a specific feature, advantage, or characteristic described in connection with an embodiment is included in at least one embodiment of the present technology. Thus, discussion of the features and advantages, and similar language, throughout this specification may, but do not necessarily, refer to the same embodiment. 
     The above Detailed Description of examples and embodiments of the invention is not intended to be exhaustive or to limit the invention to the precise form disclosed above. While specific examples for the invention are described above for illustrative purposes, various equivalent modifications are possible within the scope of the invention, as those skilled in the relevant art will recognize. For example, while processes or blocks are presented in a given order, alternative implementations may perform routines having steps, or employ systems having blocks, in a different order, and some processes or blocks may be deleted, moved, added, subdivided, combined, and/or modified to provide alternative or sub-combinations. The teachings of the present disclosure provided herein can be applied to other systems, not necessarily the system described above. The elements and acts of the various embodiments described above can be combined to provide further embodiments. All of the patents and applications and other references identified herein, including any that may be listed in accompanying filing papers, are incorporated herein by reference. Aspects of the present disclosure can be modified, if necessary, to employ the systems, functions, and concepts of the various references described above to provide yet further embodiments of the present disclosure. 
     In general, the terms used in the following claims should not be construed to limit the present disclosure to the specific embodiments disclosed in the specification, unless the above Detailed Description section explicitly defines such terms. Accordingly, the actual scope of the present disclosure encompasses not only the disclosed embodiments, but also all equivalent ways of practicing or implementing the present disclosure. 
     From the foregoing, it will be appreciated that specific embodiments of the invention have been described herein for purposes of illustration, but that various modifications may be made without deviating from the spirit and scope of the various embodiments of the invention. Further, while various advantages associated with certain embodiments of the invention have been described above in the context of those embodiments, other embodiments may also exhibit such advantages, and not all embodiments need necessarily exhibit such advantages to fall within the scope of the invention. Accordingly, the invention is not limited, except as by the appended claims. Moreover, although certain aspects of the invention are presented below in certain claim forms, the applicant contemplates the various aspects of the invention in any number of claim forms. Accordingly, the applicant reserves the right to pursue additional claims after filing this application to pursue such additional claim forms, in either this application or in a continuing application.