Machining system using supercritical fluids

Abstract

To improve a machining system that utilizes a machining fluid. Improvements to machining systems utilizing machining fluids including supercritical fluids are described. Some systems may provide centralized distribution of supercritical machining fluids and / or lubricants to multiple machining tools within a machining facility. Other systems may allow for selective delivery of multiple machining fluids to machining tools. For example, supercritical and non-supercritical machining fluids may be selectively delivered to machining tools as desired for a particular machining process.

Description

[Technical Field]

[0001] Field FIELD OF THE INVENTION

[0001] The disclosed embodiments relate to machining systems that utilize supercritical machining fluids. [Background technology]

[0002] background

[0002] Machining tools, such as milling systems, lathes, computer numerical control (CNC) systems, robotic drills, and / or machining centers, may use machining fluids, such as metalworking fluids, to provide cooling and / or lubrication during the cutting or shaping process. The machining fluid may be supplied to the interface between the cutting tool and the workpiece during the cutting or shaping process. In some applications, the machining fluid may be supplied externally, such as by routing the machining fluid through a series of pipes and to one or more nozzles that direct the machining fluid at the cutting interface. In other applications, the machining fluid may be routed to the interface internally, for example, through the tool holder and / or through the cutting tool (e.g., through one or more channels formed in the cutting tool).

[0003]

[0003] Conventional machining fluids may include mixtures that include a cooling fluid (such as air, water, liquid carbon dioxide, or liquid nitrogen) for cooling the cutting zone during the cutting process and a lubricant (such as oil, minimum quantity lubrication (MQL) fluid, or synthetic fluid) for lubricating the cutting zone. In some cases, machining fluids that include only oil, emulsion, or synthetic fluid may be appropriate. In some applications, supercritical fluids, such as supercritical carbon dioxide (scCO2), have been utilized and used as part of the machining fluid. Summary of the Invention [Means for solving the problem]

[0004] overview In one embodiment, a machining system includes a first machining fluid supply constructed and arranged to supply a supercritical machining fluid and a second machining fluid supply constructed and arranged to supply a second machining fluid. The system further includes a first valve having a first inlet fluidly coupled to the first machining fluid supply, a second inlet fluidly coupled to the second machining fluid supply, and an outlet fluidly coupled to a machining tool. The first valve is movable between a first position, in which the first valve is configured to supply the supercritical machining fluid to the machining tool, and a second position, in which the first valve is configured to supply the second machining fluid to the machining tool.

[0005] In another embodiment, a machining system includes a lubricant reservoir fluidly coupled to the plurality of machining tools, and one or more pumps coupled to the lubricant reservoir and configured to supply lubricant from the lubricant reservoir to each machining tool of the plurality of machining tools, wherein the one or more pumps are configured to supply a predetermined flow rate of lubricant to the plurality of machining tools, and the lubricant is combined with a machining fluid at each machining tool of the plurality of machining tools.

[0006] In a further embodiment, a system for dispensing a supercritical machining fluid includes a storage tank constructed and arranged to store a liquid, the storage tank having an outlet disposed adjacent a bottom of the storage tank, and a pressure booster fluidly coupled to the outlet. The pressure booster is constructed and arranged to receive the liquid from a first storage tank and increase the pressure of the liquid to a first pressure above the critical pressure of the liquid. The system further includes a heater fluidly coupled to the pump and constructed and arranged to increase the temperature of the liquid to a first temperature above the critical temperature of the liquid. Increasing the pressure of the liquid to the first pressure and increasing the temperature of the liquid to a second pressure converts the liquid to a supercritical fluid. The system also includes a storage vessel fluidly coupled to the heater and a dispensing system fluidly coupled to the storage vessel. The storage vessel is constructed and arranged to receive the supercritical fluid and maintain the supercritical fluid at a pressure above the liquid's critical pressure and a temperature above the liquid's critical temperature, and the distribution system is constructed and arranged to deliver the supercritical fluid from the storage vessel to the plurality of machining tools.

[0007]

[0007] In yet another embodiment, a method for detecting a leak in a machining system including a supercritical machining fluid includes supplying the supercritical machining fluid to a machining tool, measuring the temperature of a portion of the machining tool, detecting a temperature drop that exceeds a predetermined temperature drop, and generating a leak indication signal in response to detecting a temperature drop that exceeds the predetermined temperature drop.

[0008]

[0008] It should be understood that the foregoing concepts, and additional concepts discussed below, may be arranged in any suitable combination, as the present disclosure is not limited in this respect. Moreover, other advantages and novel features of the present disclosure will become apparent from the following detailed description of various non-limiting embodiments when considered in conjunction with the accompanying figures.

[0009] BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component shown in various figures may be represented by a like numeral. For clarity, not every component is labeled in every drawing. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic diagram of a machining system utilizing supercritical fluids, according to some embodiments. [Figure 2]

[0011] FIG. 1 is a schematic diagram of a centralized supercritical machining fluid distribution system according to some embodiments. [Figure 3]

[0012] 1 is a schematic diagram of a valve assembly, according to some embodiments. [Figure 4]

[0013] 1 is a schematic diagram of a machining tool including temperature monitoring, according to some embodiments. [Figure 5]

[0014] FIG. 1 is a schematic diagram of a centralized lubricant supply system, according to some embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0011] Detailed Description

[0015] Embodiments described herein relate to improvements in machining systems that utilize machining fluids containing supercritical fluids, such as supercritical carbon dioxide (scCO2) or supercritical nitrogen. The inventors have recognized that supercritical machining fluids can offer numerous advantages over conventional machining fluids, such as water-based machining fluids, oil-based machining fluids (e.g., neat oil), minimum quantity lubrication (MQL) fluids, or synthetic machining fluids. As used herein, a supercritical fluid refers to a fluid maintained above its critical point (i.e., at a temperature above its critical temperature and a pressure above its critical pressure). For example, the critical temperature and pressure of carbon dioxide are 31.1°C and 72.8 atm, respectively, which are readily achievable in industrial applications. Above the critical point, distinct liquid and gas phases do not exist; instead, supercritical fluids exhibit properties of both liquids and gases. For example, supercritical fluids may exhibit the flow and expansion behavior of a gas while also being able to dissolve materials like a liquid. In machining applications, rapidly expanding supercritical machining fluids may provide better cooling and / or more efficient heat transfer, may provide better mixing with or dissolution of lubricants, and / or may allow the use of less lubricant compared to conventional water-based machining fluids. Additionally, as described in more detail below, in some cases, rapidly expanding supercritical machining fluids with dissolved lubricants may precipitate small, fast-moving lubricant droplets, which may provide superior lubrication compared to conventional machining fluids.

[0012]

[0016] While it has been recognized that some of the above-described properties of supercritical fluids provide many advantages in machining applications, the inventors have also recognized and appreciated that some aspects of conventional machining system designs may not be well-suited for use with supercritical fluids. In particular, the different properties and / or behavior of supercritical fluids compared to conventional machining fluids may require a different approach to machining system design to accommodate supercritical fluids. For example, the inventors have recognized advantages associated with a system that can supply a fluid to a machining tool below its critical pressure and / or critical temperature and subsequently increase the pressure and / or temperature of the fluid at the machining tool to produce a supercritical machining fluid. In some applications, the fluid may be stored above its critical pressure (e.g., in a storage tank associated with the machining tool and / or in a centralized storage system configured to distribute high-pressure fluid to multiple machining tools), and the fluid may be heated to a temperature above its critical temperature at each machining tool when supercritical machining fluid is required for the cutting process. In other applications, the supercritical machining fluid may be stored in one or more storage tanks specially designed to store the supercritical machining fluid and maintain the fluid above its critical point during storage before it is needed during a cutting operation. As described in more detail below, in some embodiments, the supercritical fluid may be prepared and stored in a supercritical state and distributed to multiple machining tools via a centralized supply system.

[0013]

[0017] Furthermore, depending on the particular embodiment, the temperature of the supercritical machining fluid can be adjusted as needed for different types of supercritical fluids and / or for thermal management of a particular cutting process. For example, for systems utilizing scCO2, the temperature can be maintained above 100°C. In some cases, maintaining a warmer temperature can be advantageous, for example, to provide small, high-velocity particles without supercooling. For example, maintaining a temperature substantially above the critical temperature of the supercritical fluid can be advantageous in some cutting processes.

[0014]

[0018] Additionally, the inventors have recognized and understood that systems utilizing supercritical machining fluids may require various components, such as pumps, valves, seals, and / or other plumbing devices, to be selected to be compatible with the supercritical machining fluid. For example, such components may be used in connection with a system for supplying the supercritical machining fluid to a machining tool (such as from a centralized distribution system and / or from a supercritical fluid system associated with a particular machining tool). Additionally, the inventors have recognized and understood that many components within a machining tool may be incompatible with supercritical fluids. For example, many seals used in conventional machining tools are formed from materials that are easily solubilized by supercritical machining fluids, which can lead to degradation and / or failure of the machining system. Accordingly, some aspects described herein relate to materials (e.g., for seal devices) that are suitable for use with supercritical machining fluids, as described in more detail below.

[0015]

[0019] While various embodiments described herein refer to supercritical machining fluids, it should be understood that the present disclosure is not limited to supercritical machining fluids that are maintained in their supercritical state throughout the machining process. In particular, in some embodiments, the machining fluid may start in its supercritical state but may drop below its critical temperature and / or pressure during the machining process. The inventors have recognized and appreciated that many of the advantages described herein associated with the supercritical state may still be maintained even when the machining fluid drops below its critical point. For example, in some applications, mixing a lubricant into the supercritical machining fluid may advantageously cause the lubricant to disperse into small droplets once the temperature and / or pressure of the supercritical machining fluid drops below their respective critical values, such that the machining fluid loses its supercritical properties. In particular, the inventors have recognized that while the machining fluid is in a supercritical state, the lubricant may be completely dissolved in the matching fluid (i.e., the lubricant may be completely soluble in the supercritical fluid), and as a result, such droplets may not exist while the machining fluid is in a supercritical state. Thus, in some embodiments, lubricant droplets may only form when the machining fluid transitions from the supercritical state.

[0016]

[0020] In some cases, when a supercritical machining fluid is supplied to an open environment, such as when the supercritical fluid is supplied from a nozzle or orifice in a cutting tool or tool holder at a cutting interface, the supercritical machining fluid may expand rapidly. The inventors have recognized that this expansion of the supercritical fluid may aid in precipitating smaller, more uniformly sized lubricant droplets compared to those achievable with conventional machining fluids. Thus, while in some applications the supercritical machining fluids described herein may no longer be in a supercritical state at the point in the machining process when the part is being cut, cooled, and / or lubricated (e.g., within the spindle of the machining tool and / or at the cutting interface), the use of supercritical machining fluids may still provide numerous advantages compared to conventional machining fluids, especially when the supercritical machining fluid is supplied as close to the cutting zone as practicable.

[0017]

[0021] According to some aspects, the systems described herein may provide for centralized preparation and storage of supercritical fluids and distribution of the supercritical machining fluid to one or more machining tools located within a machining facility (or other suitable environment). In one embodiment utilizing a supercritical machining fluid including scCO2, the scCO2 can be prepared and stored centrally, and the scCO2 can be distributed as needed to various machining tools within the machining facility. For example, the scCO2 can be prepared by pumping liquid CO2 from a bulk storage tank through a pressure booster (e.g., a pump such as a cryogenic pump, a gas blanket, or a gas booster). The pressure booster may raise the pressure of the CO2 above its critical pressure. The high-pressure CO2 can then be delivered to a heater, such as an electric vaporizer, which heats the CO2 to a temperature above its critical temperature, thereby converting the CO2 to its supercritical state. The scCO2 is then transferred to a high-pressure, large-volume storage vessel constructed and arranged to maintain the scCO2 in a supercritical state. For example, the storage container may be suitably insulated to avoid heat loss (which could cause the temperature to drop below a critical temperature). Additionally, in some embodiments, the storage container may include an active temperature control system including one or more heating elements, a temperature sensor, and a controller configured to maintain the scCO2 above a critical temperature. The scCO2 may be stored in the storage container until the machining fluid is needed within the machining facility (e.g., at one or more machining tools within the machining facility), at which point the scCO2 may be drawn from the storage container and distributed as needed to the machining facility.

[0018]

[0022] In some embodiments, the storage vessel may comprise one or more large storage tanks and / or multiple smaller storage tanks (e.g., cylinders) coupled together to form a larger storage volume. Alternatively, or in addition, several storage vessels may each be configured to store machining fluid at a temperature and / or pressure below the critical temperature and / or pressure. In such embodiments, the machining fluid stored in the storage vessel may pass through one or more additional heaters and / or pressure boosters before being distributed to the machining tools to return the machining fluid to its supercritical state. Furthermore, some systems may use multiple storage vessels that can be configured to distribute scCO2 to a subset of machining tools within a machining facility. In this manner, multiple storage vessels can be arranged as distribution cells configured to distribute to specific portions of a machining facility or to specific subsets of machining tools within a machining facility.

[0019]

[0023] The inventors have further recognized and appreciated many advantages associated with a system that provides centralized distribution of lubricant to multiple machining tools around a machining facility. In particular, conventional lubricant supply systems typically utilize individual pumps associated with each machining tool to supply a desired volumetric flow rate of lubricant to the machining tool. The inventors have appreciated that such an arrangement can lead to significant expense. For example, in some applications, high-pressure lubricant dosing pumps can represent a significant portion of the total cost of the machining tool, and individual pumps can lead to significant maintenance and repair costs, especially in machining facilities that include a large number of machining tools. Accordingly, some aspects described herein relate to a centralized distribution system that can supply multiple machining tools with required volumetric flows of lubricant from a central lubricant source. The inventors have appreciated that such an arrangement can provide a simpler and less expensive lubricant supply compared to conventional systems and can provide a more robust system requiring less maintenance and repair. Furthermore, such a centralized lubricant supply system can allow for a significantly larger lubricant reservoir compared to reservoirs that may be installed on individual machines, which allows for a longer run time before the lubricant must be replaced or refilled.

[0020]

[0024] In one embodiment, the lubricant distribution system includes a high-pressure lubricant pump constructed and arranged to distribute a metering network of lubricant throughout a machining facility, for example, to supply lubricant to up to 50 separate machining tools. Furthermore, the volumetric flow rate of lubricant distributed to each machining tool may be independently adjustable to provide the amount of lubricant required for a particular machining process. In some embodiments, the systems described herein may be configured to supply natural straight oil, emulsion concentrate, synthetic oil lubricant, and / or other lubricant formulations soluble in supercritical fluids (e.g., scCO2), as the present disclosure is not limited to any particular lubricant distributed by the lubricant distribution system. In some embodiments, at each machining tool in the machining facility, an MQL fluid (or other suitable lubricant) may be combined with a supercritical fluid, and the supercritical fluid may be supplied to the machining tool (e.g., from a centralized source, such as those described above, or from a supercritical fluid generation system associated with the particular machining tool) to form a supercritical machining fluid that is then supplied to the cutting interface of the tool. Although some embodiments of the lubricant distribution system are described in connection with systems utilizing supercritical machining fluids, it should be understood that the lubricant distribution system can also be used in applications utilizing more conventional (i.e., non-supercritical) machining fluids.

[0021]

[0025] In addition to the above, the inventors have recognized and appreciated that delivering supercritical machining fluids to machining tools can present numerous challenges not present in conventional machining systems utilizing water-based machining fluids. In particular, in systems including rotary machining tools (e.g., CNC machines, lathes, mills, etc.), the machining fluid may need to pass through the tool's rotary union before reaching the cutting interface. Due to the high pressures and gas-like behavior associated with supercritical fluids, rotary unions that may be used in the systems described herein may need to be tighter sealed than systems that use only conventional machining fluids. In some applications, rotary unions used with supercritical machining fluids may be designed with smaller diameters than systems that use non-supercritical fluids.

[0022]

[0026] Additionally, the rotary unions of the systems described herein utilizing supercritical machining fluids can be designed to accommodate repeated pressurization and decompression cycles associated with tool changes. For example, the rotary union may include a spring device within the rotary joint configured to prevent closure of the rotary joint when the rotary joint is pressurized by the pressure of the supercritical machining fluid. Some embodiments may include a reclosing mechanism for a bearingless rotary joint configured to provide lubrication to the rotary joint during a tool change. In particular, in contrast to rotary joints utilizing conventional machining fluids that can lubricate the seals during normal operation of the rotary joint, the high pressures associated with supercritical fluids can prevent lubricants from penetrating the seals of the rotary joint. Thus, in some embodiments, the seals of the rotary joint may separate during decompression associated with a tool change, allowing a thin film of lubricant to deposit on the seals to provide lubrication. Furthermore, as described in more detail below, in some embodiments, the materials used for various seal components may be selected to provide compatibility with supercritical machining fluids (e.g., to avoid undesired dissolution of the seal materials in the supercritical fluid).

[0023]

[0027] As noted above, while various embodiments utilizing centralized distribution of supercritical machining fluid and / or lubricant are described herein, it should be understood that the disclosure is not limited in this respect. For example, some embodiments may include a separate system for supplying supercritical machining fluid to an associated machining tool. For example, a supercritical machining fluid system may be coupled to a machining tool (such as a CNC machine), and the supercritical machining fluid system may supply machining fluid and / or lubricant to the tool as needed.

[0024]

[0028] According to some embodiments, machining systems designed for use with supercritical machining fluids (e.g., scCO2) may also be compatible with conventional water- and oil-based machining fluids. Thus, unlike other conventional systems based on cryogenic and / or gas-based machining fluids, the systems described herein may enable machining tool operators to easily switch between supercritical machining fluids and water- and oil-based machining fluids as needed, including during a single machining process and / or between multiple machining processes. In particular, the inventors have realized that supercritical machining fluids may have densities approaching that of water (e.g., about 80% of the density of water), and lubricants such as oils may be soluble in supercritical machining fluids. As a result, supercritical machining fluids may be able to flow through the same spindle equipment used for water-based machining fluids. In contrast, water-based machining fluids may be incompatible with other non-supercritical machining fluids, such as cryogenic fluids (e.g., cryogenic CO2 or liquid nitrogen), which may require specialized equipment that may not be suitable for water-based fluids. As a result, systems based on such other non-supercritical machining fluids would require significant modification to provide compatibility with water-based fluids. In contrast, with the systems described herein, the selection of the desired machining fluid (e.g., water-based or supercritical) can be made on a day-to-day, part-by-part, and / or tool-by-tool basis without significant modification of the machining tool, thereby providing operator flexibility in selecting the appropriate machining fluid for a particular machining process.

[0025]

[0029] In some embodiments, the machining tool may include a valve device to facilitate switching between a supercritical machining fluid and a conventional (e.g., water-based) machining fluid. For example, the valve device may be located upstream of a rotary union, turret, or other suitable connection to the cutting portion of the machining tool, such as a spindle of the machining tool. The machining fluid may flow through the valve device and the cutting portion of the tool and ultimately be directed to the cutting interface. The valve device may include a three-way fluid selection valve, such as a pneumatically actuated ball valve, which may include an orifice large enough not to restrict the volumetric flow rate of the water- or oil-based machining fluid even under high pressure. Furthermore, the valve device may be configured within the machining system so that the ball valve does not form a final restriction point for the supercritical machining fluid to avoid undesirable expansion of the supercritical fluid within the system.

[0026]

[0030] In some embodiments, the valve arrangement may also include a three-way valve disposed between a supply of supercritical fluid (e.g., from a central distribution source) and the fluid selection valve. This three-way valve may enable selective venting of the supercritical machining fluid to reduce or purge pressure within the machining tool, such as during tool changes or when conventional water- or oil-based machining fluids are being used. In some applications, the three-way valve may be a solenoid valve operably coupled to a controller of an associated machining tool, such as a controller of a CNC machine. The controller may send an electronic signal to the three-way valve to selectively control the flow of supercritical fluid to the machining tool, such as in response to a signal from the controller that additional coolant is needed at the cutting interface. In some cases, the valve arrangement may further include one or more check valves, such as a check valve disposed between a supply of conventional water- or oil-based machining fluid and the machining fluid selection valve. Such check valves may further help facilitate simple and rapid transitions between the use of supercritical machining fluid and conventional water- or oil-based machining fluids in the machining tool.

[0027]

[0031] Additionally, in some applications, the valve arrangement may further include a lubricant inlet through which a separate lubricant (e.g., an MQL lubricant) may be introduced and supplied to the machining tool (e.g., prior to the rotary union, turret, or other suitable connection to the machining tool). For example, in one embodiment including a fluid selection valve as described above, the lubricant inlet may be located downstream relative to the fluid selection valve so that the lubricant (e.g., an MQL lubricant) can be selected as an alternative to the supercritical machining fluid or a water- or oil-based machining fluid as needed.

[0028]

[0032] The inventors have further recognized and appreciated the advantages associated with monitoring the pressure of a supercritical machining fluid supplied to a rotary union, turret, or other suitable connection to a cutting component (e.g., spindle) of a machining tool. In particular, due to the high pressures associated with supercritical fluids, pressure monitoring can be useful to ensure that the pressure behind the spindle is purged before performing operations such as a tool change, as well as to monitor the pressure of the supercritical machining fluid during machining operations to ensure that the pressure is maintained within a desired operating range. Such pressure monitoring is not necessary in conventional machining systems utilizing non-supercritical machining fluids; however, when using supercritical fluids, pressure monitoring can be used, for example, to improve machine safety, detect leaks, and / or ensure that supercritical conditions are achieved. Furthermore, by controlling the pressure of the supercritical fluid, which in some cases can affect the machining process, different cooling and / or flow characteristics can be achieved.

[0029]

[0033] In some embodiments, a pressure transducer associated with the spindle of the machining tool can be installed as a component of a valve assembly of the machining tool. For example, in connection with the valve assembly described above, the pressure transducer can be installed between a three-way valve associated with the supercritical fluid source and a fluid selection valve. In other embodiments, such as embodiments that do not include a fluid selection valve, the pressure transducer can be installed between the three-way valve associated with the supercritical fluid source and a rotary union (or other suitable connection) of the machining tool. Alternatively, or in addition, in some embodiments, one or more pressure transducers can be provided downstream of the rotary union, such as within a portion of the machining tool, such as the spindle.

[0030]

[0034] In certain embodiments, the pressure transducer may be operably coupled to a controller, such as a controller of a CNC machine (or other suitable machining tool). The CNC machine controller may be configured to verify that pressure upstream of the spindle (i.e., upstream of the rotary union) has been purged before proceeding with the tool change operation. If pressure purging is required, the controller may communicate with a three-way valve associated with the supercritical fluid source, as described above.

[0031]

[0035] According to some aspects, a machining tool may be configured to monitor the temperature of one or more components of the machining tool, such as a spindle of a rotary machining tool. The inventors have recognized and appreciated that the gas-like behavior of supercritical fluids—specifically, their tendency to expand rapidly when exposed to an open environment and / or when transitioning from a smaller volume region to a larger volume region—can be utilized to detect problems with the machining tool, such as a leak in the supercritical machining fluid. In particular, the rapid expansion of the supercritical fluid results in rapid cooling of the supercritical fluid, which in turn causes cooling of components of the machining system in contact with the supercritical fluid. Thus, in some embodiments, temperature monitoring can be used to detect a decrease in temperature of one or more components of the machining tool caused by a leak in the supercritical machining fluid. In this manner, a leak in the machining tool can be detected and repaired before the machining tool suffers substantial damage or failure due to, for example, freezing of one or more components of the machining tool. In particular, components that may be susceptible to such damage or failure include, but are not limited to, the bearings of the spindle of the machining tool, the drive motor, the tool holder, the connection between the tool holder and the spindle, and / or the cutting tool held in the tool holder.

[0032]

[0036] In some embodiments, the systems described herein may utilize existing temperature sensors included in machining tools, such as CNC machines, to perform the leak detection described above. In particular, CNC machines often include thermocouples, resistance temperature detectors, or other suitable temperature sensors for monitoring the temperature of the spindle (e.g., to monitor the spindle for overheating). However, the inventors have recognized that these temperature sensors can also be configured to monitor temperature drops for leak detection. For example, the CNC machine's controller can be configured to detect a leak based on a predetermined drop in the spindle's temperature, e.g., from a normal operating temperature, which may be room temperature or above, to a temperature below about 0°C. Thus, in some embodiments, the predetermined temperature drop can be a drop of between about 20°C and about 40°C from the normal operating temperature. In some embodiments, a leak can be detected based on a predetermined rate of change of temperature. Upon detecting a leak, the CNC machine may sound an alarm and halt cutting operations, including the supply of supercritical fluid to the spindle. In this manner, the CNC machine can be protected from further damage that could otherwise result from the leak.

[0033]

[0037] While the above-described embodiments utilize temperature monitoring within the machining tool to detect supercritical fluid leaks, it should be understood that temperature monitoring may be used in other parts of the system as well to detect supercritical fluid leaks. For example, in connection with the centralized supercritical fluid distribution system described above, the temperature of one or more components of the distribution system, such as storage vessels and / or pipes, may be monitored to detect supercritical fluid leaks. As with the above-described embodiments, the system may be configured to detect temperature drops in various components beyond a predetermined temperature drop, which may correspond to rapid expansion and cooling of the supercritical fluid in the event of a leak. Once a leak is detected, the system may be configured to stop the flow of supercritical fluid to the affected components.

[0034]

[0038] As noted above, the inventors have recognized and appreciated that systems utilizing supercritical machining fluids may require the selection of materials for various components of the machining system to provide compatibility with the supercritical fluid. For example, in some applications, it may be beneficial to utilize stainless steel tubing to route the supercritical machining fluid from a storage vessel (e.g., a centralized storage vessel as described above) to a rotary union (or other suitable connection) where the machining fluid is supplied to the cutting portion of the machining tool (e.g., the spindle of a rotary machining tool). The dimensions of the stainless steel tubing may be selected based on the desired operating pressure range associated with the supercritical machining fluid supply system. For example, in one embodiment, stainless steel tubing having an outer diameter of about 0.1 inches to about 0.5 inches (e.g., 0.25 inches) and a wall thickness of about 0.02 inches to about 0.05 inches (e.g., about 0.035 inches) may be suitable. However, it should be understood that the present disclosure is not limited to specific dimensions of stainless steel tubing for supplying supercritical machining fluids. Additionally, other materials for the tubing that may be suitable include, but are not limited to, alloy steel, brass, titanium, hastelloy, aluminum, and / or high pressure hose.

[0035]

[0039] Additionally, in some applications, some portions of the system (such as in a CNC system) may require the use of flexible tubing to deliver the supercritical machining fluid to the cutting interface. In such systems, the flexible tubing can be selected based on compatibility with the supercritical machining fluid as well as the required operating temperature and pressure range. For example, in one embodiment utilizing an scCO2-based machining fluid, suitable tubing materials include, but are not limited to, Parker Paraflex 520N-4 hydraulic hose, PTFE-lined braided stainless steel hose such as Swagelok B series, convoluted stainless steel core hose such as Swagelok FX series, polyamide core hose such as Fluke DH400, and nylon core hose such as Swagelok 7R series.

[0036]

[0040] In addition to the above, various seals, O-rings, and joints used in the systems described herein that may come into contact with supercritical machining fluids can be selected based on the operating temperature and pressure range associated with the supercritical fluid and to provide compatibility with the supercritical fluid. For example, the operating pressure can be between about 100 and 140 bar, and in some cases up to about 200 bar, 300 bar, 400 bar, or more, and the operating temperature can be between about 20° C. and about 100° C. In some embodiments, suitable materials for seals and O-rings that can operate in these pressure and temperature ranges and also provide compatibility with supercritical fluids such as scCO2 include, but are not limited to, Kalrez 0090, hard durometer Viton, fluorinated ethylene propylene (FEP), and polytetrafluoroethylene (PTFE)-encapsulated Viton. In some applications, it may be beneficial to select the highest durometer seal or O-ring available made of the appropriate material. Additionally, joints that may be suitable for connecting various portions of the systems described herein include, but are not limited to, hydraulic fittings such as National Pipe Thread (NPT), British Standard Pipe (BSP and / or BSPP), Joint Industrial Council (JIC), and / or other compression fittings rated at 200 bar or greater.

[0037]

[0041] Additionally, while some embodiments described herein include a lubricant (such as one or more oils, metalworking fluid emulsion concentrates, and / or MQL fluids) that is mixed with a supercritical fluid to form a supercritical machining fluid, it should be understood that the present disclosure is not limited to machining fluids that include lubricants. For example, in some applications, the supercritical fluid alone may provide sufficient cooling and / or lubrication during the cutting process. In other applications, a coolant fluid (e.g., water) may be added to the supercritical machining fluid to add mass and / or additional heat transfer capability to the machining fluid. Thus, it should be understood that supercritical machining fluid can refer to a supercritical fluid with or without additional components, such as a lubricant or coolant.

[0038]

[0042] Turning now to the figures, certain non-limiting embodiments are described in further detail. It should be understood that the present disclosure is not limited to only the specific embodiments described herein, and that the various systems, components, features, and methods described in connection with these embodiments can be used individually and / or in any desired combination.

[0039]

[0043] 1 is a schematic diagram of a machining system 100 utilizing a supercritical machining fluid. The system 100 includes a machining tool 110 (e.g., a CNC machine, a lathe, and / or a turret lathe) that includes a cutting interface 112 where cutting or forming operations can be performed. For example, the cutting interface can include a rotating spindle to which a cutting tool can be attached. Some systems, such as a turret lathe system, can include multiple cutting tools that can be selected based on the particular cutting operation desired. The machining tool 110 further includes a coupling 114, such as a rotary union, that couples the cutting interface to a machining fluid system 120.

[0040]

[0044] The machining fluid system 120 includes a machining fluid supply 122 and a lubricant supply 124. In some embodiments, the machining fluid supply may be configured to supply a supercritical machining fluid (e.g., scCO2) to the machining tool 110, although embodiments configured for conventional machining fluids (i.e., non-supercritical fluids) may also be suitable. The machining fluid and lubricant are supplied to the coupling 114 via supply lines 126 and 128, respectively. Additionally, the machining tool 110 includes a controller 118 configured to control various aspects of the operation of the machining tool, such as the operation of the cutting tool during cutting operations. The controller 118 is also operably coupled to a valve arrangement 130 such that the controller may control the supply of the supercritical fluid and / or the lubricant to the machining tool 110.

[0041]

[0045] Depending on the particular embodiment, machining fluid source 120 may be a stand-alone system that may be coupled to an individual cutting tool to supply supercritical machining fluid to cutting interface 112 during cutting operations, or may be a centralized distribution system configured to supply machining fluid to a machining center or multiple cutting tools within a cutting center. Similarly, lubricant source 124 may be a stand-alone system coupled to an individual machining tool, or the lubricant source may be a centralized lubricant distribution system configured to supply lubricant to multiple machining tools within a machining facility.

[0042]

[0046] Furthermore, it should be understood that the present disclosure is not limited to any particular type of machining tool 110. For example, the tool may include a CNC machine, a lathe, a turret lathe, a mill, a robotic drill, or any other suitable machining system.

[0043]

[0047] Referring now to FIG. 2 , one embodiment of a system 200 for preparing and dispensing an scCO2-based supercritical machining fluid is described in more detail. The system includes a storage tank 210 configured to contain liquid CO2. For example, the storage tank 210 can be a vacuum-jacketed vertical tank in which the liquid CO2 is maintained at a pressure of approximately 20 bar and a temperature of approximately −18° C. The liquid CO2 is supplied from the storage tank 210 to one or more pumps 220, such as cryogenic pumps. In some embodiments, the liquid CO2 can be drawn from the bottom of the storage tank 210. In this manner, the system can utilize the head pressure of a liquid column within the storage tank to maintain a minimum net positive suction head (NPSH) at the suction port of the pump 220. The pump is configured to compress the liquid CO2 and increase the pressure of the liquid CO2 above its critical pressure, for example, to approximately 200 bar. The high-pressure liquid CO2 is then directed through a heater 230, such as an electric vaporizer, which heats the CO2 to a temperature above its critical temperature (i.e., above 31°C). By heating the fluid above its critical temperature, the high-pressure liquid CO2 is converted to its supercritical state (scCO2). The scCO2 is then transferred to a high-pressure, large-capacity storage vessel 240, which may include one or more heating elements, insulation, and closed-loop controls configured to maintain the temperature to ensure the scCO2 remains above the critical temperature. When needed for machining operations, the scCO2 is then distributed from the storage vessel 240 to a machining facility 250, which includes multiple machining tools 110, where the scCO2 can be delivered to the individual machining tools.

[0044]

[0048] While a single storage tank 210 is shown in FIG. 2, it should be understood that other configurations may be suitable. For example, as noted above, some embodiments may use multiple smaller storage tanks (e.g., cylinders) coupled together to form a single larger storage volume. In some embodiments, such a storage tank may be located within the machining facility 250. Alternatively, or in addition, some embodiments may use multiple storage tanks and / or several multiple smaller storage tanks arranged to form distribution cells, such distribution cells configured to distribute scCO to different portions of the machining facility and / or to different subsets of machining tools within the machining facility.

[0045]

[0049] Additionally, in some embodiments, system 200 may further include a centralized lubricant distribution system 260. As described above, this lubricant distribution system may be constructed and arranged to distribute a lubricant (e.g., an MQL lubricant) to multiple machining tools 110, where the lubricant may be mixed with the scCO2 machining fluid. Alternatively, each machining tool may include a separate lubricant source coupled to a supply of scCO2 from system 200.

[0046]

[0050] In the illustrated embodiment, scCO2 is prepared and stored outside of the machining facility 250 and distributed to machining tools 110 located within the machining facility 250. However, embodiments are contemplated in which some or all of the components of the system 200 are located within the machining facility 250. For example, in one embodiment, the storage tank 210 may be located outside of the machining facility, while the pump 220, heater 230, and storage vessel 240 may be located within the machining facility. Additionally, while three machining tools 110 are shown in the figures, it should be understood that the centralized distribution system described herein may be used with any suitable number of machining tools.

[0047]

[0051] 3 shows a schematic flow chart illustrating the operation of a valve apparatus 300, according to some embodiments. The valve apparatus 300 can provide switching between supercritical and conventional (non-supercritical) machining fluids as may be required for different matching operations. The system includes a supercritical fluid supply 302 and a non-supercritical fluid supply 304, each of which is fed to a first three-way valve 306 configured to selectively allow flow of the desired machining fluid to a machining tool 308. Depending on the particular embodiment, the first three-way valve can be a manual valve or an automatic valve, such as a pneumatically controlled valve.

[0048]

[0052] A second three-way valve 310 is disposed between the supercritical fluid supply 302 and the first three-way valve 306. The second three-way valve 312 may be configured to allow supercritical fluid to be routed to the exhaust 312, such as to purge pressure within the machining tool 308 during a tool change. In some embodiments, the second three-way valve may be a solenoid valve, although other types of valves may be suitable. A pressure sensor 314 is disposed between the first three-way valve 306 and the second three-way valve 310 to monitor the pressure behind the machining tool. In some applications, one or more operations of the machining tool may be controlled by the machine tool's controller based on the measured pressure. For example, the machine tool may be configured to stop cutting operations and purge pressure (via the second three-way valve) if the pressure increases above a predetermined level. Additionally, the flow of non-supercritical fluid to the first three-way valve 306 may be controlled via a valve 316 (such as a check valve) associated with the non-supercritical fluid supply 304 .

[0049]

[0053] In some embodiments, the valve arrangement may be further configured to supply a lubricant from a lubricant supply 318 to the machining fluid, and the flow of the lubricant may be controlled via a valve 320, such as a check valve, associated with the lubricant supply. Similarly, the valve arrangement may include an additive supply 322 configured to supply an additive, such as compressed air, to the machining fluid, and a valve 324 may control the supply of the additive. In some cases, the lubricant supply and the compressed air supply may be used to provide a third machining fluid option (i.e., an air-dispersed lubricant, such as an MQL lubricant).

[0050]

[0054] While the above-described embodiments are configured to selectively supply supercritical and non-supercritical fluids, it should be understood that other configurations may be suitable. For example, some embodiments may include supplying two different supercritical fluids (e.g., scCO2 premixed with different lubricants) and using a three-way valve to selectively supply one of the supercritical fluids. Furthermore, while the valving is depicted as being external to the machining tool, it should be understood that the disclosure is not limited in this respect, and some embodiments may include valving disposed within the machining tool to enable selection of an appropriate machining fluid from multiple machining fluids supplied to the machining tool.

[0051]

[0055] 4 is a schematic diagram of one embodiment of a machining tool 400 including a temperature monitor configured to detect leaks of supercritical machining fluid. In particular, the machining tool 400 includes a spindle 402 to which a cutting tool 404 is attached via a tool holder 406. The machining tool 400 includes one or more drive motors 408 configured to drive rotation of the cutting tool 404 during cutting operations. In the illustrated embodiment, the supercritical machining fluid may be supplied to the matching tool via a supercritical fluid supply 410. The supercritical fluid may be supplied to the cutting interface in any suitable manner, such as through the machining tool 400 (including via the spindle 402 and tool holder 406).

[0052]

[0056] One or more temperature sensors 412 are provided in the machining tool and configured to monitor the temperature of one or more components of the machining tool 400, including the temperature of the spindle 402. The temperature sensors 412 are connected to a controller 414, which may be configured to detect a supercritical fluid leak based on a predetermined decrease in temperature measured by the temperature sensors. As described above, supercritical fluids can cool rapidly as they expand, which can occur if the supercritical fluid is undesirably leaking within the machining tool. In some embodiments, the temperature decrease corresponding to a detected leak can be a decrease in the operating temperature of the cutting machine to a temperature below 0° C. Upon detecting a leak condition, the controller may stop operation of the cutting machine, for example, by stopping the drive motor 408 and / or stopping the supply of supercritical fluid via the supercritical fluid supply 410. In other embodiments, the controller may be configured to switch the machining fluid to an aqueous machining fluid upon detecting a leak. In this way, various components of the machining tool, such as the spindle and associated spindle bearings, drive motor, and / or cutting tool, can be protected from further damage that may result from leakage.

[0053]

[0057] 5, one embodiment of a centralized lubricant supply system 500 is described in more detail. The system 500 includes a centralized lubricant reservoir 502, a pump 504 (e.g., a hydraulic pump), and a storage vessel 506 (e.g., a hydraulic accumulator), from which lubricant can be distributed to multiple lubricant modules 510. Each lubricant module can be coupled to one or more machining tools 512 and configured to provide a desired flow rate of lubricant to the attached machining tools. In particular, each lubricant module 510 can include a pressure-reducing regulator 514, a needle valve 516, an optional flow meter 518, and a solenoid valve 518. The regulator and valve can be configured to provide a desired flow rate and / or pressure of lubricant for a particular machining process of the machining tools 512. Additionally, each lubricant module 510 may include a machining fluid supply 522 through which a machining fluid, such as a supercritical machining fluid, may flow and mix with the lubricant before being delivered to the machining tool 512. Although a lubricant distribution system including four lubricant modules is shown in FIG. 5, it should be understood that the present disclosure is not limited to any particular number of lubricant modules and / or machining tools to which the lubricant delivery system delivers lubricant.

[0054]

[0058] 5 as being disposed external to the associated machining tool 512, it should be understood that other configurations may be suitable. For example, in some embodiments, the lubricant module may be configured as an internal component of the machining tool (e.g., the lubricant module may be disposed within a housing of the machining tool) or may be mounted directly to the machining tool. Similarly, it should be understood that one or more additional components and / or systems described above, such as components of a machining fluid distribution system, may also be configured as components of the machining tool and may be mounted directly to and / or disposed within a housing of the machining tool.

[0055]

[0059] As noted above, in some embodiments, the systems described herein may include one or more controllers configured to operate various aspects of the machining system, such as, for example, operation of one or more valves operatively coupled to one or more pressure and temperature sensors. Such embodiments described herein may be implemented in any of numerous ways. For example, the embodiments may be implemented using hardware, software, or a combination thereof. When implemented in software, the software code may execute on any suitable processor or collection of processors, whether provided on a single computer or distributed across multiple computers. Such processors may be implemented as integrated circuits with one or more processors within integrated circuit components, including commercially available integrated circuit components known in the art under names such as CPU chips, GPU chips, microprocessors, microcontrollers, or coprocessors. Alternatively, the processor may be implemented in custom circuits such as ASICs, or semi-custom circuits resulting from configuring programmable logic devices. As yet another alternative, the processor may be part of a larger circuit or semiconductor device, whether commercially available, semi-custom, or custom. As a particular example, some commercially available microprocessors have multiple cores, such that one or a subset of those cores may constitute a processor, although a processor may be implemented using any suitable form of circuitry.

[0056]

[0060] Furthermore, it should be understood that a computer may be embodied in any of several forms, such as a rack-mounted computer, a desktop computer, a laptop computer, or a tablet computer. Additionally, a computer may be embedded in a device not generally considered a computer but having suitable processing capabilities, such as a smartphone or other suitable portable or fixed electronic device.

[0057]

[0061] The controller and / or computer may also have one or more input and output devices. These devices may be used, among other things, to present a user interface. Examples of output devices that may be used to provide a user interface include a printer or display screen for visual presentation of output, or a speaker or other sound-generating device for audible presentation of output. Examples of input devices that may be used for a user interface include a keyboard and pointing devices such as a mouse, touchpad, and digitizing tablet. As another example, a computer may receive input information via voice recognition or in other audible form.

[0058]

[0062] Such controllers and / or computers may be interconnected by one or more networks of any suitable form, including a local area network or a wide area network, such as an enterprise network or the Internet. Such networks may be based on any suitable technology and may operate according to any suitable protocol, and may include wireless networks, wired networks, or fiber optic networks.

[0059]

[0063] Also, the various methods or processes outlined herein may be coded as software executable on one or more processors using any one of a variety of operating systems or platforms. Further, such software may be written using any of a number of suitable programming languages ​​and / or programming or scripting tools, and may be compiled as executable machine code or intermediate code that runs on a framework or virtual machine.

[0060]

[0064] In this regard, the embodiments described herein may be embodied as a computer-readable storage medium (or multiple computer-readable media) (e.g., computer memory, one or more floppy disks, compact disks (CDs), optical disks, digital video disks (DVDs), magnetic tapes, flash memory, circuit configurations of field programmable gate arrays or other semiconductor devices, or other tangible computer storage media) encoded with one or more programs that, when executed on one or more computers or other processors, implement the various embodiments described above. As is evident from the foregoing examples, a computer-readable storage medium may retain corresponding information for a sufficient period of time to provide computer-executable instructions in a non-transitory form. Such one or more computer-readable storage media may be removable, such that one or more programs stored thereon can be loaded into one or more different computers or other processors to implement various aspects of the present disclosure, as described above. As used herein, the term “computer-readable storage medium” encompasses only non-transitory computer-readable media that can be considered an article of manufacture (i.e., an article of manufacture) or machine. Alternatively or additionally, the present disclosure may be embodied as a computer-readable medium other than a computer-readable storage medium, such as a propagated signal.

[0061]

[0065] The terms "program" or "software" are used generically herein to refer to any type of computer code or set of computer-executable instructions that can be used to program a computer or other processor to implement various aspects of the present disclosure, as described above. Furthermore, according to one aspect of this embodiment, it should be understood that one or more computer programs that, when executed, perform the methods of the present disclosure need not reside on a single computer or processor, but may be distributed in a modular manner among a number of different computers or processors to implement various aspects of the present disclosure.

[0062]

[0066] Computer-executable instructions may be in many forms, such as program modules, executed by one or more computers or other devices. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. Typically, the functionality of the program modules may be combined or distributed as desired in various embodiments.

[0063]

[0067] Additionally, data structures may be stored in any suitable format on a computer-readable medium. For ease of explanation, data structures may be depicted as having fields related by location within the data structure. Such relationships may be achieved by allocating storage to the fields with locations within the computer-readable medium that in turn convey the relationship between the fields. However, any suitable mechanism may be used to establish relationships between information in fields of a data structure, including the use of pointers, tags, or other mechanisms that establish relationships between data elements.

[0064]

[0068] Additionally, some actions are described as being taken by a "user." It should be understood that a "user" need not be a single individual, and that in some embodiments, actions attributed to a "user" may be performed by a team of individuals and / or by an individual in combination with computer-assisted tools or other mechanisms.

[0065]

[0069] While the present teachings have been described in conjunction with various embodiments and examples, it is not intended that the present teachings be limited to such embodiments or examples. On the contrary, the present teachings encompass various alternatives, modifications, and equivalents, as will be appreciated by those skilled in the art. Accordingly, the foregoing description and drawings are by way of example only.

Claims

1. a first machining fluid supply constructed and arranged to supply a supercritical machining fluid; a second machining fluid supply constructed and arranged to supply a second machining fluid; a first valve having a first inlet fluidly coupled to the first machining fluid supply, a second inlet fluidly coupled to the second machining fluid supply, and an outlet fluidly coupled to a machining tool, the first valve being movable between a first position, where the first valve is configured to supply the supercritical machining fluid to the machining tool, and a second position, where the first valve is configured to supply the second machining fluid to the machining tool; A machining system comprising:

2. The machining system of claim 1 , wherein the second machining fluid is a non-supercritical machining fluid.

3. 2. The machining system of claim 1, wherein the supercritical machining fluid is a first supercritical machining fluid and the second machining fluid is a second supercritical machining fluid different from the first supercritical machining fluid.

4. The machining system of claim 1 , wherein the supercritical machining fluid comprises supercritical carbon dioxide.

5. The machining system of claim 1 , wherein the first valve comprises a three-way valve.

6. 6. The machining system of claim 5, wherein the three-way valve is a pneumatically operated three-way ball valve.

7. The machining system of claim 1 , further comprising a second valve disposed between the first machining fluid supply and the first valve.

8. The machining system of claim 7 , wherein the second valve is movable to a purge position configured to release pressure between the machining tool and the second valve.

9. 8. The machining system of claim 7, further comprising a pressure sensor disposed between the first valve and the second valve, the pressure sensor configured to measure a pressure between the machining tool and the second valve.

10. The machining system of claim 1 , further comprising a lubricant supply configured to supply a lubricant to the machining tool.

11. a lubricant reservoir fluidly coupled to the plurality of machining tools; one or more pumps coupled to the lubricant reservoir and configured to supply lubricant from the lubricant reservoir to each machining tool of the plurality of machining tools, the one or more pumps configured to supply a predetermined flow rate of lubricant to the plurality of machining tools, the lubricant being combined with a machining fluid at each machining tool of the plurality of machining tools; A machining system comprising:

12. The machining system of claim 11 , wherein the lubricant is soluble in the machining fluid.

13. The machining system of claim 11 , wherein the lubricant is combined with a supercritical machining fluid in at least one machining tool of the plurality of machining tools.

14. The machining system of claim 13 , wherein the supercritical machining fluid comprises supercritical carbon dioxide.

15. The machining system of claim 11 , wherein the lubricant comprises at least one selected from the group of oil, MQL fluid, and premixed lubricant formulation.

16. 1. A system for dispensing a supercritical machining fluid, comprising: a storage tank constructed and arranged to store a liquid, the storage tank having an outlet disposed adjacent a bottom of the storage tank; a pressure booster fluidly coupled to the outlet, the pressure booster constructed and arranged to receive the liquid from the first storage tank and raise the pressure of the liquid to a first pressure above a critical pressure of the liquid; a heater fluidly coupled to the pump, the heater constructed and arranged to raise a temperature of the liquid to a first temperature above a critical temperature of the liquid, wherein raising the pressure of the liquid to the first pressure and raising the temperature of the liquid to the second pressure causes the liquid to convert to a supercritical fluid; and a storage vessel fluidly coupled to the heater, the storage vessel constructed and arranged to receive the supercritical fluid and maintain the supercritical fluid at a pressure above the critical pressure of the liquid and a temperature above the critical temperature of the liquid; a distribution system fluidly coupled to the reservoir and constructed and arranged to supply the supercritical fluid from the reservoir to a plurality of machining tools; A system comprising:

17. The system of claim 16 , wherein the liquid comprises liquid carbon dioxide.

18. 20. The system of claim 17, wherein the supercritical fluid comprises supercritical carbon dioxide.

19. 17. The system of claim 16, wherein the pressure booster is at least one selected from the group consisting of a cryogenic pump, a gas blanket, and a gas booster.

20. The system of claim 16 , wherein the heater is an electric vaporizer.

21. The system of claim 16 , wherein the storage vessel comprises one or more heating elements.

22. 22. The system of claim 21, wherein the storage vessel comprises a controller configured to control the heating element to maintain the supercritical fluid above its supercritical temperature.

23. The system of claim 16 , wherein the storage vessel comprises a plurality of tanks fluidly coupled to one another.

24. The system of claim 16 , wherein the reservoir is one of a plurality of reservoirs, each reservoir of the plurality of reservoirs being coupled to a subset of the machining tools of the plurality of machining tools.

25. The system of claim 16 , further comprising a lubricant distribution system constructed and arranged to supply lubricant to said plurality of machining tools.

26. 26. The system of claim 25, wherein the lubricant is combined with the supercritical fluid at each machining tool of the plurality of machining tools.

27. 26. The system of claim 25, wherein the lubricant is combined with the supercritical fluid before being delivered to the plurality of machining tools.

28. The system of claim 16 , wherein the plurality of machining tools are located within a machining facility and the storage tank, pump, heater, and storage vessel are located outside the machining facility.

29. 1. A method for detecting leaks in a machining system containing a supercritical machining fluid, comprising: supplying a supercritical machining fluid to a machining tool; measuring a temperature of a portion of the machining tool; detecting a temperature decrease exceeding a predetermined temperature decrease; and generating a leak indication signal in response to detecting a temperature decrease beyond said predetermined temperature decrease; A method comprising:

30. 30. The method of claim 29, wherein the temperature of the portion of the machining tool is measured with a temperature sensor coupled to a controller of the machining tool.

31. 31. The method of claim 30, wherein the controller is configured to transmit the leak indication signal.

32. 30. The method of claim 29, further comprising interrupting operation of the machining tool in response to detecting a temperature decrease beyond the predetermined temperature decrease.

33. 30. The method of claim 29, further comprising interrupting the supply of the supercritical machining fluid and supplying a non-supercritical machining fluid to the machining tool in response to detecting a temperature decrease beyond the predetermined temperature decrease.

34. 30. The method of claim 29, wherein the predetermined temperature decrease corresponds to a decrease in temperature to a temperature of about 0°C.

35. 30. The method of claim 29, wherein the predetermined temperature decrease is a temperature decrease of between about 20°C and about 40°C.

Images