Abstract:
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.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    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.  
           [0002]    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.  
           [0003]    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.  
           [0004]    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.  
           [0005]    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.  
           [0006]    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. 5,244,051.  
           [0007]    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.  
           [0008]    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  
         [0009]    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.  
           [0010]    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.  
           [0011]    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.  
           [0012]    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.  
           [0013]    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.  
           [0014]    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.  
           [0015]    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.  
           [0016]    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. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]    [0017]FIG. 1 is a diagrammatic view of an automatic screw machine which incorporates the present invention;  
         [0018]    [0018]FIG. 2 is a block diagram of the components of an apparatus having a sensor for monitoring a variable of a machine coolant or lubricant and components for cleaning and providing a calibration check of such sensor according to the present invention;  
         [0019]    [0019]FIG. 3 is a diagrammatic view of input and output manifolds utilized in conjunction with the coolant and lubricant monitoring assembly according to the present invention; and  
         [0020]    [0020]FIG. 4 is a diagrammatic view of a coolant and lubricant monitoring assembly according to the present invention located at a site remote from a monitoring site. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0021]    Referring now to FIG. 1, an automatic screw machine  10  incorporates various carriages  12  and magazines  14  for workpieces and tools which cooperate to manufacture various and sundry machine parts (not illustrated). It is to be understood that the automatic screw machine  10  is illustrative only and that the apparatus and method of the present invention may be and is intended to be utilized with such automatic screw machines  10 , 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 fluids  16 .  
         [0022]    Such cooling and lubricating fluids  16  are typically stored in a sump  18  and may be supplied to the machine  10  under pressure by a pump  20  in a line  22 . A return line  24  provides the cooling and lubricating fluid  16  directly to the sump  18 . A second return and inlet or supply line  26  provides the cooling and lubricating fluid  16  to a coolant and lubricant monitoring assembly  30 . Fluid  16  departing the coolant and lubricant monitoring assembly  30  is returned in an outlet line  32  to the sump  18  and thence recirculated.  
         [0023]    Referring now to FIG. 2, the inlet or supply line  26  includes a first pressure gauge  36  which 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 line  26  terminates in a normally closed, two position first solenoid valve  38  which may be opened or closed by a controller  40  to supply or inhibit a flow of the cooling or lubricating fluid  16  to the coolant and lubricant monitoring assembly  30 . When the solenoid valve  38  is open, the cooling or lubricating fluid  16  is provided to a high pressure pump  42 . The pump  42 , which is driven by an electric motor  43 , is capable of increasing the pressure of the fluid  16  to approximately 80 p.s.i. The actual operating pressure is adjusted by the restriction provided by a flow adjustment or restrictions device  44 . The restriction provided by the flow adjustment device  44  is increased to increase pressure in the supply line  46  and is reduced to lower pressure therein, the preferred or optional operating pressure in the supply line  46  being a function of the type of cooling and lubricating fluid  16 . A second pressure gauge  48  reads and indicates the pressure at the output of the high pressure pump  40  in the supply line  46 . Once again, the second pressure gauge  48  may be a conventional (visual) gauge or a transducer providing a signal to a remote location.  
         [0024]    As just described, the flow adjustment device  44  permits control of the pressure of the fluid  16  moving in the supply line  46 . The pressurized cooling and lubricating fluid  16  is provided to a sensor assembly housing  50  through a small orifice  51  having a diameter on the order of 0.125 inches (3 mm). The fluid  16  which passes through the flow adjustment device  44  and thus not through the supply line  46  also flows to the sensor assembly housing  50 . The sensor assembly housing  50  removably receives a refraction type concentration sensor  52  such as that available from several manufacturers including K-Patents, Naperville, Ill., AFAB Enterprises, Eustis, Fla., and Misco, Cleveland, Ohio. The concentration sensor  52  includes a face against which the flow of cooling and lubricating fluid  16  through the orifice  51  under an elevated pressure impinges. Output signals or data from the concentration sensor  52  are provided in output leads  54 . Fluid  16  flows out from the sensor assembly housing  50  and may impinge upon, engage or pass through additional or optional sensors  56  such 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 fluid  16 .  
         [0025]    The cooling and lubricating fluid  16  then travels to a normally closed second solenoid valve  58  which is activated and allows the measured cooling or lubricating fluid  16  to exit the monitoring assembly  30  through a second flow adjustment device  62 . The second flow adjustment device  62  provides an adjustable restriction which ensures maintenance of suitable pressure within the monitoring assembly  30 . The cooling or lubricating fluid  16  returns in the outlet line  32  to the sump  18  and associated equipment.  
         [0026]    Described immediately above are the components of the coolant and lubricant monitoring assembly  30  relating to sensing of variables under routine operating conditions. These components constitute the path of the cooling or lubricating fluid  16  taken by a small percentage of the fluid  16  circulating in the system illustrated in FIG. 1 as it is bypassed through the monitoring assembly  30 .  
         [0027]    The coolant and lubricant monitoring assembly  30  also includes components adapted and intended to clean the concentration sensor  52  and any optional sensors  56 . Thus, the monitoring assembly  30  includes a supply of a concentrated cleaner contained in a storage vessel  72  which is provided to a chemical metering pump  74 . Preferably, the concentrated cleaner is and acts as a solvent for both the constituents and contaminants of the particular cooling and lubricating fluid  16  utilized such that its addition thereto facilitates softening, emulsification and removal of contaminants in the monitoring assembly  30 .  
         [0028]    The chemical metering pump  74  is activated for a preselected period of time by a timing feature in the controller  40 . When commanded to operate by the controller  40 , the chemical metering pump  74  operates for a preselected period of time to inject a controlled amount of the concentrated cleaner through a check valve  78  into the sensor assembly housing  50 . The period of time is adjustable to accommodate and compensate for different cooling and lubricating fluids  16  and different concentrated cleaners.  
         [0029]    Also associated with the cleaning function, is a bypass or cleaning loop  80  having a normally open third solenoid valve  82  which is operated by the controller  40  and a check valve  84  which is in fluid communication with the outlet of the third solenoid valve  82 . A normally closed fourth solenoid valve  86  is also operated by the controller  40  and opens to dump fluid containing the concentrated cleaner or any other fluid within the coolant and lubricant monitoring assembly  30  to a waste vessel  88 .  
         [0030]    Operation of the coolant and lubricant monitoring assembly  30  in both operating, i.e., monitoring, mode and cleaning mode will now be described.  
         [0031]    The first solenoid valve  38  is normally closed and when activated, receives cooling and lubricating fluid  16  in the line  26  from the external system. Simultaneously, the second normally closed solenoid valve  58  is also activated, providing an outlet for the incoming fluid  16 . Pressure of the supplied cooling and lubricating fluid  16  is monitored by the first pressure gauge  36 . With the normally open third solenoid valve  82  deactivated, fluid  16  readily flows through the bypass or cleaning loop  80  for a timed interval, flushing and displacing whatever fluid the bypass or cleaning loop  80  previously contained.  
         [0032]    When the above flushing interval is complete, the normally open third solenoid valve  82  is activated and closes the bypass or cleaning loop  80 . This action directs all incoming fluid  16  to the high pressure pump  42 . The electric motor  43  of the pump  42  is activated to assist drawing in the cooling and lubricating fluid  16  to be measured and filling the various components of the coolant and lubricant monitoring system  30 , flushing and displacing the previously contained fluid. The fluid  16  is thus provided to the sensor assembly housing  50 , the concentration sensor  52  and other optional sensors  56  as will be readily appreciated. The normally closed second solenoid valve  58  remains activated and therefore open and permits fluid  16  to return to the main system through the flow adjustment device  62  and the return line  32 .  
         [0033]    When a measurement cycle is completed, the high pressure pump  42  is stopped and the controller  40  signals the chemical metering pump  74  to inject a measured amount of a concentrated cleaner into the system through the check valve  78 . The operating time of the metering pump  74  and thus the amount of concentrated cleaner injected is controlled by and can be adjusted by adjustment of software in the controller  40 . Next, the normally closed first solenoid valve  38  is deactivated to close it, the normally closed second solenoid valve  58  is deactivated to close it and the normally open third solenoid valve  82  is deactivated to open it. The high pressure pump  42  is activated and the fluid  16  which now includes the concentrated cleaner is forced at high pressure onto the surfaces of the concentration sensor  52  to clean it and clean as well any optional sensors  56 . The aforementioned bypass or cleaning loop  80  now functions as a fluid return path to the high pressure pump  42  so the cooling and lubricating fluid  16  including the cleaning concentrate can be re-circulated past the sensors.  
         [0034]    This cleaning cycle continues under control of the controller  40  for a period of time determined by previous experiment or examination to be sufficient to properly clean the concentration sensor  52  and any optional sensors  56 . The cooling and lubricating fluid  16  with the cleaner concentrate may remain in the system  30  and circulate at timed intervals, if desired, until a new measurement is required or it may be released. To release the fluid  16  containing the cleaner concentrate, the first solenoid valve  38  is activated to provide incoming fluid  16  and the second solenoid valve  58  is activated to allow egress of the fluid  16  present in the assembly  30 . In this state, fluid readily flows through the bypass or cleaning loop  80  for a timed interval, removing the fluid  16  containing the concentrated cleaner. When that interval is complete, the normally open third solenoid valve is activated and closes the bypass or cleaning loop  80 . This action directs all incoming fluid to the pump  42 . The electric motor  43  of the high pressure pump  42  is activated to assist drawing in the fluid  16  to be measured and filling the various components of the coolant and lubricant monitoring system  30  other than the bypass loop, thereby removing the fluid  16  containing the concentrated cleaner, allowing it to return to the main system  32 . Alternatively, the normally closed second solenoid valve  58  is deactivated and at the same time, the normally closed fourth solenoid valve  86  is activated, thereby allowing the fluid  16  to flow to the waste container  88 .  
         [0035]    Referring now to FIG. 3, the coolant and lubricant monitoring assembly  30  may 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 line  26  providing fluid to the coolant and lubricant monitoring assembly  30  is an inlet manifold  90  having a plurality of independently operable inlet solenoid valves having their outlets in fluid communication therewith. Likewise, in fluid communication with the outlet line  32  is a second, outlet manifold  100  which has a plurality of independently operable outlet solenoid valves.  
         [0036]    With regard to the inlet manifold  90 , a plurality of solenoid operated valves  92 A,  92 B,  92 C,  92 D and  92 E are provided with various fluids from various independent drilling, cutting, grinding and other manual and CNC machines having cooling or lubricating fluids  16  desired to be monitored. The solenoid valves  92 A,  92 B,  92 C,  92 D and  92 E are controlled by a controller  40  (or an optional controller  94  which is linked to the controller  40  in order to achieve proper sequencing and system identification) and operate in concert but not simultaneously with a plurality of outlet valves  102 A,  102 B,  102 C,  102 D and  102 E. That is, the controller  94  actuates the inlet valve  92 A to receive fluid  16  and subsequently may operate the outlet valve  102 A such that fluid  16  may be returned to the same system  1 . Correspondingly, the valves  92 A and  102 A may be closed and the valves, for example,  92 C and  102 C may be opened such that cooling and lubricating fluid  16  from a third system is provided to the coolant and lubricant monitoring assembly  30  and returned thereto.  
         [0037]    It should be understood that while five input valves  92 A,  92 B,  92 C,  92 D and  92 E as well as a corresponding five outlet valves  102 A,  102 B,  102 C,  102 D and  102 E 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 assembly  30 .  
         [0038]    Additionally, cleaning fluid such as de-ionized water or calibration fluids may be provided to the assembly  30  through the inlet manifold  90  and removed through the outlet manifold  100 . Specifically, an inlet solenoid valve  96  may be provided with de-ionized water from an appropriate source. The inlet solenoid valve  96  is operated to provide de-ionized water to the assembly  30 . Similarly, a calibration or other fluid may be provided to an inlet solenoid valve  98 . The calibration fluid may be utilized in the coolant and lubricant monitoring assembly  30  to perform a calibration check on the various sensors  52  and  56  or achieve a desired operational or control function. As used herein calibration check means to utilize a standard reference or calibration fluid in the monitoring assembly  30  which, when read by one of the sensors  52  or  56 , provides a current calibration signal or value to the controller  40  or other associated equipment. This current calibration signal can then be compared to a known, stored, reference value and the current accuracy of the sensor  52  or  56  can 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 sensors  52  and  56 . The calibration fluid may then be released from the monitoring assembly  30  through a corresponding outlet valve  108  which provides the fluids to the waste vessel  88 .  
         [0039]    Referring now to FIG. 4, an installation having real time control and remote monitoring capability of at least one variable in a cooling and lubricating fluid system  110  is illustrated. Again, the system utilizes an automatic screw machine  10  or 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 assembly  30  of the present invention, the sump  18  and the pump  20 . The system  110  also includes supplies of one or more coolant or lubricant constituents contained within storage tanks or vessels  112  and  114 . The storage vessels  112  and  114  may contain concentrated coolants, lubricants, pH adjusters or any other fluid or constituent of a cooling and lubricating fluid  16  which may be necessary to provide, augment or adjust the fluid characteristics. The vessels  112  and  114  preferably include electrically operated solenoid outlet valves  116  and  118 , respectively, that are controlled by the controller  40  which receives signals from the various coolant and lubricant sensors  52  and  56 , illustrated in FIG. 2.  
         [0040]    A deficiency in some sensed characteristic or variable of the cooling and lubricating fluid  16  or other out of tolerance operating condition may be promptly and accurately corrected by activating one or both of the solenoid valves  116  and  118  to 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 vessels  112  and  114  of 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.  
         [0041]    A first interface assembly  120  is coupled to the controller  40  by lines  121  and by land lines  122 A such as telephone lines, internet connections, fiber optic lines or may be utilized in a wireless mode through microwave transmission or satellite transmission  122 B to a second interface assembly  124  at a remote location. The second interface assembly  124  is preferably coupled to a computer  126  having a display device  128  such as a cathode ray tube or plasma display, a keyboard  132  for inputting data and a printer  134  and/or other electronic media or optical read/write storage device for providing a permanent record of operations and conditions.  
         [0042]    So configured, data sensed by the sensors  52  and  56  of the coolant and lubricant monitoring assembly  30  is provided to the controller and interface assembly  120 , transmitted to the interface assembly  124  and the computer  126 . The data may then be stored therein or displayed on the display device  128  or printed out on the printer  134 . 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 printer  134  and/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.  
         [0043]    It should be appreciated that the present system, particularly the coolant and lubricant monitoring assembly  30  may 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 assembly  30 . 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 fluid  16  utilized in a specific system.  
         [0044]    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.