Method and apparatus for measuring a variable in a lubricant/coolant system

An automatic system for monitoring/controlling a variable of a machine or metalworking fluid system also achieves cleaning and optionally, a calibration check of the sensor of the variable. The system includes one or more sensors for variables such as pH, fluid concentration, conductivity, temperature and the like, a supply of a cleaning agent and associated valves and conduits for connecting the automatic system to a fluid to be measured. A cleaning cycle can be scheduled as necessary to clean and/or check calibration of the sensors and ensure accurate measurement of sensed variables. If desired, the data regarding the sensed variables may be utilized to perform corrective action in real time.

BACKGROUND OF THE INVENTION

The invention relates generally to a method and apparatus for measuring a variable in a fluid system and more particularly to a method and apparatus for measuring a fluid variable in a lubricant or coolant system and cleaning and undertaking a calibration check of the measurement device to ensure accurate measurement.

Most machine tools that remove metal, including automatic screw machines and computer controlled machining centers rely upon cooling and lubricating fluids applied to the machining site to improve tool life, enhance the surface finish of the machined region, increase cutting speeds and remove heat from the machining process to minimize distortion of the part and interference with or reduction of properties achieved by heat treatment.

Maintaining optimum concentrations and fluid characteristics of such cooling and lubricating fluids is desirable from the standpoints of maintaining optimum machining conditions, maximizing coolant and lubricant service life and therefore minimizing overall operating expense.

Numerous devices and methods have been developed to optimally use both cutting equipment and cooling and lubricating fluids. For example, U.S. Pat. No. 4,757,307 teaches a method of sensing the heat generated by a cutting tool to determine the condition of the tool.

U.S. Pat. No. 6,134,930 discloses a system wherein independent or distinct lubricating and cooling fluids are utilized to achieve distinct operational benefits.

Frequently, system operating conditions at the work site may be monitored and the information provided over land lines to a remote site where decisions regarding adjustment of fluid parameters are made and transmitted to the work site. Such a system is disclosed in U.S. Pat. No. 5,224,051.

In U.S. Pat. No. 6,336,362, a method and system for measuring and reporting the liquid level of tanks is taught. The system is particularly suited for detecting and reporting the level of liquid propane in industrial, commercial and residential tanks in order to prevent exhaustion of the gas supply at a particular site.

From the foregoing, it is apparent that monitoring and control systems relating to fluids, fluid quantity and fluid condition are diversified. Moreover, it is apparent that methods and apparatus addressing particular operational problems such as accurate measurement of a fluid variable such as pH, concentration, conductivity or temperature have not been fully developed. For example, many sensors are subject to fouling when exposed to coolants and lubricants and particularly so when the coolants and lubricants become contaminated. The present invention addresses and solves such problems.

BRIEF SUMMARY OF THE INVENTION

An automatic system for monitoring/controlling a variable of a machine or metalworking fluid system also achieves cleaning and optionally, a calibration check of the sensor of the variable. The system includes one or more sensors for variables such as pH, fluid concentration, conductivity, temperature and the like, a supply of a cleaning agent and associated valves and conduits for connecting the automatic system to a fluid to be measured. A cleaning cycle can be scheduled as necessary to clean and/or check calibration of the sensor or sensors and ensure accurate measurement of sensed variables. If desired the input to the system and output from the system may be connected to separate manifolds having corresponding pluralities of inputs and outputs. Also if desired, the data regarding the sensed variables may be utilized to perform corrective action in real time. Finally, sensed and operational data may be transmitted over telephone lines, the internet or other means to a remote site where monitoring and recording of the variables and operation may be undertaken.

Thus it is an object of the present invention to provide a method for monitoring at least one variable of a machine coolant or lubricant.

It is a further object of the present invention to provide an apparatus for monitoring at least one variable of a machine coolant or lubricant.

It is a still further object of the present invention to provide an apparatus and method for monitoring and controlling at least one variable of a machine coolant or lubricant.

It is a still further object of the present invention to provide a method and apparatus for cleaning and checking calibration of a fluid variable sensor.

It is a still further object of the present invention to provide a method and apparatus for cleaning and checking calibration of a fluid variable sensor for machine coolants and lubricants.

It is a still further object of the present invention to provide monitoring of at least one variable of machine coolants and lubricants and provide such information to a remotely located site.

Further objects and advantages of the present invention will become apparent by reference to the following description of the preferred embodiment and appended drawings wherein like reference numbers refer to the same component, element or feature.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now toFIG. 1, an automatic screw machine10incorporates various carriages12and magazines14for workpieces and tools which cooperate to manufacture various and sundry machine parts (not illustrated). It is to be understood that the automatic screw machine10is illustrative only and that the apparatus and method of the present invention may be and is intended to be utilized with such automatic screw machines10, computer numerical controlled (CNC) devices and machining centers, lathes, grinders, milling machines, and all manner of equipment for cutting, forming, boring, milling, drilling and shaping of typically though not exclusively metal parts wherein the aforementioned processes are facilitated by application of cooling and/or lubricating fluids16.

Such cooling and lubricating fluids16are typically stored in a sump18and may be supplied to the machine10under pressure by a pump20in a line22. A return line24provides the cooling and lubricating fluid16directly to the sump18. A second return and inlet or supply line26provides the cooling and lubricating fluid16to a coolant and lubricant monitoring assembly30. Fluid16departing the coolant and lubricant monitoring assembly30is returned in an outlet line32to the sump18and thence recirculated.

Referring now toFIG. 2, the inlet or supply line26includes a first pressure gauge36which may be either a visually readable device such as a conventional Bourdon tube pressure gauge or may be a transducer which provides a signal to a remote location. The input or supply line26terminates in a normally closed, two position first solenoid valve38which may be opened or closed by a controller40to supply or inhibit a flow of the cooling or lubricating fluid16to the coolant and lubricant monitoring assembly30. When the solenoid valve38is open, the cooling or lubricating fluid16is provided to a high pressure pump42. The high pressure pump42, which is driven by an electric motor43, is capable of increasing the pressure of the fluid16to approximately 80 p.s.i. The actual operating pressure is adjusted by the restriction provided by a flow adjustment or restriction device44. The restriction provided by the flow adjustment device44is increased to, increase pressure in a supply line46and is reduced to lower pressure therein, the preferred or optional operating pressure in the supply line46being a function of the type of cooling and lubricating fluid16. A second pressure gauge48reads and indicates the pressure at the output of the high pressure pump42in the supply line46. Once again, the second pressure gauge48may be a conventional (visual) gauge or a transducer providing a signal to a remote location.

As just described, the flow adjustment device44permits control of the pressure of the fluid16moving in the supply line46. The pressurized cooling and lubricating fluid16is provided to a sensor assembly housing50through a small orifice51having a diameter on the order of 0.125 inches (3 mm). The fluid16which passes through the flow adjustment device44and thus not through the supply line46also flows to the sensor assembly housing50. The sensor assembly housing50removably receives a refraction type concentration sensor52such as that available from several manufacturers including K-Patents, Naperville, Ill., AFAB Enterprises, Eustis, Fla., and Misco, Cleveland, Ohio. The concentration sensor52includes a face against which the flow of cooling and lubricating fluid16through the orifice51under an elevated pressure impinges. Output signals or data from the concentration sensor52are provided in output leads54. Fluid16flows out from the sensor assembly housing50and may impinge upon, engage or pass through additional or optional sensors56such as a temperature sensor, a pH sensor, an electrical conductivity sensor, a turbidity sensor or other sensors providing information regarding diverse variables and the condition of the cooling or lubricating fluid16.

The cooling and lubricating fluid16then travels to a normally closed second solenoid valve58which is activated and allows the measured cooling or lubricating fluid16to exit the monitoring assembly30through a second flow adjustment device62. The second flow adjustment device62provides an adjustable restriction which ensures maintenance of suitable pressure within the monitoring assembly30. The cooling or lubricating fluid16returns in the outlet line32to the sump18and associated equipment.

Described immediately above are the components of the coolant and lubricant monitoring assembly30relating to sensing of variables under routine operating conditions. These components constitute the path of the cooling or lubricating fluid16taken by a small percentage of the fluid16circulating in the system illustrated inFIG. 1as it is bypassed through the monitoring assembly30.

The coolant and lubricant monitoring assembly30also includes components adapted and intended to clean the concentration sensor52and any optional sensors56. Thus, the monitoring assembly30includes a supply of a concentrated cleaner contained in a storage vessel72which is provided to a chemical metering pump74. Preferably, the concentrated cleaner is and acts as a solvent for both the constituents and contaminants of the particular cooling and lubricating fluid16utilized such that its addition thereto facilitates softening, emulsification and removal of contaminants in the monitoring assembly30.

The chemical metering pump74is activated for a preselected period of time by a timing feature in the controller40. When commanded to operate by the controller40, the chemical metering pump74operates for a preselected period of time to inject a controlled amount of the concentrated cleaner through a check valve78into the sensor assembly housing50. The period of time is adjustable to accommodate and compensate for different cooling and lubricating fluids16and different concentrated cleaners.

Also associated with the cleaning function, is a bypass or cleaning loop80having a normally open third solenoid valve82which is operated by the controller40and a check valve84which is in fluid communication with the outlet of the third solenoid valve82. A normally closed fourth solenoid valve86is also operated by the controller40and opens to dump fluid containing the concentrated cleaner or any other fluid within the coolant and lubricant monitoring assembly30to a waste vessel88.

The cooling and lubricating fluid16then travels to a normally closed second solenoid valve58which is activated and allows the measured cooling or lubricating fluid16to exit the monitoring assembly30through a second flow adjustment device62. The second flow adjustment device62provides an adjustable restriction which ensures maintenance of suitable pressure within the monitoring assembly30. A check valve64ensures fluid flow only out of the monitoring assembly30in the line32. The cooling or lubricating fluid16returns in the outlet line32to the sump18and associated equipment.

The first solenoid valve38is normally closed and when activated, receives cooling and lubricating fluid16in the line26from the external system. Simultaneously, the second normally closed solenoid valve58is also activated, providing an outlet for the incoming fluid16. Pressure of the supplied cooling and lubricating fluid16is monitored by the first pressure gauge36. With the normally open third solenoid valve82deactivated, fluid16readily flows through the bypass or cleaning loop80for a timed interval, flushing and displacing whatever fluid the bypass or cleaning loop80previously contained.

When the above flushing interval is complete, the normally open third solenoid valve82is activated and closes the bypass or cleaning loop80. This action directs all incoming fluid16to the high pressure pump42. The electric motor43of the high pressure pump42is activated to assist drawing in the cooling and lubricating fluid16to be measured and filling the various components of the coolant and lubricant monitoring assembly30, flushing and displacing the previously contained fluid. The fluid16is thus provided to the sensor assembly housing50, the concentration sensor52and other optional sensors56as wilt be readily appreciated. The normally closed second solenoid valve58remains activated and therefore open and permits fluid16to return to the main system through the flow adjustment device62and the return line32.

When a measurement cycle is completed, the high pressure pump42is stopped and the controller40signals the chemical metering pump74to inject a measured amount of a concentrated cleaner into the monitoring assembly30through the check valve78. The operating time of the metering pump74and thus the amount of concentrated cleaner injected is controlled by and can be adjusted by adjustment of software in the controller40. Next, the normally closed first solenoid valve38is deactivated to close it, the normally closed second solenoid valve58is deactivated to close it and the normally open third solenoid valve82is deactivated to open it. The high pressure pump42is activated and the fluid16which now includes the concentrated cleaner is forced at high pressure onto the surfaces of the concentration sensor52to clean it and clean as well any optional sensors56. The aforementioned bypass or cleaning loop80now functions as a fluid return path to the high pressure pump42so the cooling and lubricating fluid16including the cleaning concentrate can be re-circulated past the sensors52and56.

This cleaning cycle continues under control of the controller40for a period of time determined by previous experiment or examination to be sufficient to properly clean the concentration sensor52and any optional sensors56. The cooling and lubricating fluid16with the cleaner concentrate may remain in the monitoring assembly30and circulate at timed intervals, if desired, until a new measurement is required or it may be released. To release the fluid16containing the cleaner concentrate, the first solenoid valve38is activated to provide incoming fluid16and the second solenoid valve58is activated to allow egress of the fluid16present in the assembly30. In this state, fluid readily flows through the bypass or cleaning loop80for a timed interval, removing the fluid16containing the concentrated cleaner. When that interval is complete, the normally open third solenoid valve82is activated and closes the bypass or cleaning loop80. This action directs all incoming fluid to the pump42. The electric motor43of the high pressure pump42is activated to assist drawing in the fluid16to be measured and filling the various components of the coolant and lubricant monitoring assembly30other than the bypass loop80, thereby removing the fluid16containing the concentrated cleaner, allowing it to return to the main system. Alternatively, the normally closed second solenoid valve58is deactivated and at the same time, the normally closed fourth solenoid valve86is activated, thereby allowing the fluid16to flow to the waste container88.

Referring now toFIG. 3, the coolant and lubricant monitoring assembly30may also be utilized with inlet and outlet manifolds to permit it to both monitor fluids in several independent systems and be provided with various other task specific fluids. Accordingly, at the return and inlet line26providing fluid to the coolant and lubricant monitoring assembly30is an inlet manifold90having a plurality of independently operable inlet solenoid valves having their outlets in fluid communication therewith. Likewise, in fluid communication with the outlet line32is a second, outlet manifold100which has a plurality of independently operable outlet solenoid valves.

With regard to the inlet manifold90, a plurality of solenoid operated valves92A,92B,92C,92D and92E are provided with various fluids from various independent drilling, cutting, grinding and other manual and CNC machines having cooling or lubricating fluids16desired to be monitored. The solenoid valves92A,92B,92C,92D and92E are controlled by a controller40(or an optional controller94which is linked to the controller40in order to achieve proper sequencing and system identification) and operate in concert but not simultaneously with a plurality of outlet valves102A,102B,102C,102D and102E. That is, the controller94actuates the inlet valve92A to receive fluid16and subsequently may operate the outlet valve102A such that fluid16may be returned to the same system1. Correspondingly, the valves92A and102A may be closed and the valves, for example,92C and102C may be opened such that cooling and lubricating fluid16from a third system is provided to the coolant and lubricant monitoring assembly30and returned thereto.

It should be understood that while five input valves92A,92B,92C,92D and92E as well as a corresponding five outlet valves102A,102B,102C,102D and102E are illustrated, the number five is exemplary only and more or fewer valves and associated systems may be readily accommodated and utilized with the coolant and lubricant monitoring assembly30.

Additionally, cleaning fluid such as de-ionized water or calibration fluids may be provided to the assembly30through the inlet manifold90and removed through the outlet manifold100. Specifically, an inlet solenoid valve96may be provided with de-ionized water from an appropriate source. The inlet solenoid valve96is operated to provide de-ionized water to the monitoring assembly30. A first waste or outlet valve106may be appropriately activated to release the de-ionized water from the assembly30which travels to the waste vessel88. Similarly, a calibration or other fluid may be provided to an inlet solenoid valve98. The calibration fluid may be utilized in the coolant and lubricant monitoring assembly30to perform a calibration check on the various sensors52and56or achieve a desired operational or control function. As used herein calibration check means to utilize a standard reference or calibration fluid in the monitoring assembly30which, when read by one of the sensors52or56, provides a current calibration signal or value to the controller40or other associated equipment. This current calibration signal can then be compared to a known, stored, reference value and the current accuracy of the sensor52or56can be determined. If the current signal or value differs from the stored reference value, an error compensation signal sufficient to compensate for the error can be generated and utilized to normalize or correct the output value of the sensors52and56. The calibration fluid may then be released from the monitoring assembly30through a corresponding second waste or outlet valve108which provides the fluids to the waste vessel88.

Referring now toFIG. 4, an installation having real time control and remote monitoring capability of at least one variable in a cooling and lubricating fluid system110is illustrated. Again, the system utilizes an automatic screw machine10or other device such as a computer numerical controlled (CNC) device, machining center, lathe, grinder, milling machine or similar cutting, forming, boring, drilling or shaping device including, in the cooling and lubricating fluid circuit the coolant and lubricant monitoring assembly30of the present invention, the sump18and the pump20. The system110also includes supplies of one or more coolant or lubricant constituents contained within storage tanks or vessels112and114. The storage vessels112and114may contain concentrated coolants, lubricants, pH adjusters or any other fluid or constituent of a cooling and lubricating fluid16which may be necessary to provide, augment or adjust the fluid characteristics. The vessels112and114preferably include electrically operated solenoid outlet valves116and118, respectively, that are controlled by the controller40which receives signals from the various coolant and lubricant sensors52and56, illustrated in FIG.2.

A deficiency in some sensed characteristic or variable of the cooling and lubricating fluid16or other out of tolerance operating condition may be promptly and accurately corrected by activating one or both of the solenoid valves116and118to provide the necessary fluid(s) in the correct amount to correct the sensed deficiency. It should be understood that the foregoing description of two tanks or vessels112and114of constituents is illustrative only and that a single tank filled with a single constituent or a mixture of constituents or multiple (more than two) tanks with single constituents are within the purview of the present invention.

A first interface assembly120is coupled to the controller40by lines121and by land lines122A such as telephone lines, internet connections, fiber optic lines or may be utilized in a wireless mode through microwave transmission or satellite transmission122B to a second interface assembly124at a remote location. The second interface assembly124is preferably coupled to a computer126having a display device128such as a cathode ray tube or plasma display, a keyboard132for inputting data and a printer134and/or other electronic media or optical read/write storage device for providing a permanent record of operations and conditions.

So configured, data sensed by the sensors52and56of the coolant and lubricant monitoring assembly30is provided to the controller and interface assembly120, transmitted to the interface assembly124and the computer126. The data may then be stored therein or displayed on the display device128or printed out on the printer134. Operators at the remote location can thus monitor one or many remote sites and operating conditions or events occurring at the remote locations and receive data or information in real time regarding operational parameters of the various systems. Moreover, permanent records of various fluid characteristics may be created by the printer134and/or other electronic media or optical storage device. Furthermore, a record of the corrective action taken in response to data collected may also be made.

It should be appreciated that the present system, particularly the coolant and lubricant monitoring assembly30may be used with all currently utilized cooling and/or lubricating fluids. That is, soluble oils which consist of oil, an emulsifier and are typically between 10% and 90% water; synthetic fluid in which no oil is utilized and semi-synthetic fluids wherein some oil is utilized are all suitable for use with the monitoring assembly30. As noted previously, the concentrated cleaning fluid must therefore be selected to correspond from a solubility standpoint with the particular type of coolant and lubricating fluid16utilized in a specific system.

It is therefore intended that the foregoing detailed description be regarded as illustrative rather than limiting, and that it be understood that the following claims, including all equivalents, are intended to define the spirit and scope of this invention.