Abstract:
A system and method for monitoring an electrostatic powder painting process having a conveyor line adaptable for transporting articles to be electrostatically powder painted sequentially through a plurality of zones in the process. For monitoring the usage of powder paint particles, or “powder”, applied to the articles, the system and method sense a parameter associated with the amount of, or weight of, the powder in the powder delivery apparatus and displays it in real time as a powder-weight function over a period of time. For monitoring the operation of the conveyor line transporting the articles, the system and method sense the conveyor line speed and displays it in real time as a line-speed function over a period of time. For monitoring the precleaning-surface activation of the articles, the system and method sense the pH of the cleaning-surface activation solution and displays it in real time as a pH function over a period of time. For monitoring the curing of the painted articles, the system and method sense the curing temperature and displays it in real time as a temperature function over a period of time. Both short and long term periods of timer eg. 1 hr. and 12 hrs., are displayed by a single computer-monitor unit if displays are viewed sequentially, or by multiple units if displays are viewed simultaneously. The system and method allow the business owner to keep instantaneous track of the operational part of the painting process without being physically present at the conveyor line at all times or most of the time thereby freeing the business owner&#39;s time for other aspects of the business.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    Continuing application of U.S. Ser. No. 09/499,605, filed Feb. 7, 2000, which is a continuing application of U.S. Ser. No. 09/182,5860, filed Oct. 29, 1998, now U.S. Pat. No. 6,023,644 issued Feb. 8, 2000, which is a continuing application of U.S. Ser. No. 08/712,851, filed Sep. 12, 1996, now U.S. Pat. No. 5,831,855 issued Nov. 3, 1998. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    Because of the competition in todays original equipment manufacturers or OEMS, many OEMS find it necessary, or at least cost effective, to have specialists handle certain operations in the manufacture of their products. The electrostatic powder painting operation is one of those steps that many OEMS, which require their metal products to be painted, find is beneficial to have specialists perform. As a consequence there is a growing electrostatic powder painting industry which serves OEMS that need their steel, iron, aluminum and other metal products painted,  
           [0003]    The electrostatic powder painting industry is frequently small businesses that are highly competitive. To remain competitive, these small business owners often must personally manage both the business part and the operational part of their business. These business owners must maximize the productivity of their operation and minimize mistakes. Examples of costly mistakes often made are: unnecessary stoppage of the conveyor line, running out of powder, using the wrong powder, wasting powder, having too much of one powder and not enough of another, unaccounted for disappearance of powder, insufficient cleaning and surface activation of the articles received from the OEMS, and insufficient curing of the powder on the articles.  
           [0004]    Therefore, there is a need for a system and method for monitoring electrostatic powder painting processes that allow the business owner to keep track of the operational part of the painting process without being physically present at the conveyor line at all times or most of the time thereby allowing the business owner more time for the business aspects of the business.  
         SUMMARY OF THE INVENTION  
         [0005]    The monitoring systems and methods of this invention allow the owners or managers to remotely and periodically review operating parameters of their electrostatic powder painting process to quickly see if there is, or has been, a problem such as stoppage of the line, incorrect temperatures, or incorrect pH. If there has been a stoppage, the monitoring system and method prompt the manager to investigate.  
           [0006]    By not requiring a manager&#39;s physical presents at the line at all times, or if not at all times then at least less frequently, the manager is free to perform other duties such as phone conferences with customers, review of monitoring system and method records, discussions with shift supervisors, inventory review, ordering of supplies, and planning schedules and other business activities.  
           [0007]    Due to the nature of the powder paint particles, hereinafter referred to as “powder”, and the heat from elevated temperature of the large curing ovens, the line is generally a very hot, gritty and a somewhat undesirable area. Consequently frequent trips to the line for periodic inspection can easily interrupt the manager&#39;s chain of thought thereby lowering his productivity. Also, business owners generally feel that it is important for them to personally have a professional dress appearance for meeting with customers. Less time spent in the process operations part of the business, where clothing can be easily soiled, facilitates maintaining a clean dress appearance  
           [0008]    In general, the monitoring systems and methods of this invention enable managers to maintain close supervision of the line activities without having to be physically at, or make frequent visits to, the line to insure that there are no problems at the line thereby freeing the manager&#39;s time for other important matters  
           [0009]    The manager may also use the information resulting from, and produced by, the monitoring system and method of this invention to evaluate the performance of personnel and to discuss with the personnel how performance may be improved. The viewing of the displays and printed and computer records resulting from the monitoring system and method enables the manager to provide visual proof of good process control to existing and potential customers, and to research Problems discovered days, weeks or months after a particular paint job was completed.  
           [0010]    Accordingly, there is provided by the principles of this invention a system and method for monitoring an electrostatic powder painting process having a conveyor line adaptable for transporting articles to be electrostatically powder painted sequentially through a plurality of zones in the process  
           [0011]    In one embodiment the system and method comprise dispensing powder paint particles from a powder delivery means operable for applying the powder paint particles to the articles in a painting zone, sensing the amount or weight of the powder paint particles in the powder delivery means with powder amount sensing means and generating a powder amount or paint-weight associated signal therewith corresponding to real time weight of the powder paint particles in the powder delivery means and transmitting the powder-weight associated signal from the powder amount sensing means to computer-monitor means adaptable for displaying the real time weight of the powder paint particles in the powder delivery means as a powder-weight function over a predetermined period of time.  
           [0012]    In another embodiment, the computer-monitor means for displaying the powder-weight function is also adaptable for converting the powder-weight associated signal into a powder-used function or powder-consumption function corresponding to the total weight of powder removed from the powder delivery means and for displaying the real time weight of the powder used or consumed as a powder-consumption function over a predetermined period of time. In a still another embodiments the computer-monitor means for displaying the powder-weight function and for displaying the powder-consumption function, displays the powder-consumption function superimposed over the powder-weight function  
           [0013]    In one embodiment, the powder delivery means includes dispensing powder paint particles from a delivery container through a conduit to an electrostatic powder paint spray gun operable for applying the powder paint particles to the articles in a painting zone, and the system and method include sensing the weight of the delivery container and powder paint particles therein with the powder amount sensing means and generating a powder-weight associated signal therewith corresponding to real time weight of the delivery container and powder paint particles therein. In a further embodiment the computer-monitor means for displaying the powder-weight function is also operable for automatically subtracting a delivery container tare weight from the real time weight of the delivery container and powder paint particles therein thereby calculating a second powder-weight functions and for displaying the second powder-weight function over a predetermined period of time.  
           [0014]    In one embodiment, the predetermined period of time for displaying the powder-weight function spans at least about 1 hour. In another embodiments the powder-weight function includes a short term powder-weight function and a long term powder-weight function. In a further embodiment, the short term powder-weight function spans at least about 1 hour, and the long term powder-weight function spans at least about 8 hours. In a still further embodiments the long term powder-weight function spans at least about 12 hours.  
           [0015]    In one embodiment, the computer-monitor means for displaying the powder-weight function is also operable for inputing a predetermined low weight parameter and for activating an alarm signal when the powder-weight associated signal reaches the predetermined low weight parameter. In this embodiments when the weight of the powder paint particles in the powder delivery means reaches the predetermined low level the alarm signal is activated so that the operators of the process will know to add more powder to the powder delivery means.  
           [0016]    In another embodiment, the system and method further comprise a data input device proximate the conveyor line for inputing a paint identifier code to the computer-monitor means for displaying the powder-weight function.  
           [0017]    In one embodiment, the system and method comprise sensing the speed of the conveyor line with speed sensing means and generating a line-speed signal therewith corresponding to real time line speed, and transmitting the line-speed signal from the speed sensing means to computer-monitor means adaptable for displaying the real time line speed as a line-speed function over a predetermined period of time.  
           [0018]    In one embodiment, the predetermined period of time for displaying the line-speed function also spans at least about 1 hour. In another embodiment, the line-speed function includes a short term line-speed function and a long term line-speed function. In a further embodiment, the short term line-speed function spans at least about 1 hour, and the long term line-speed function spans at least about 8 hours. In a still further embodiment, the long term line-speed function spans at least about 12 hours.  
           [0019]    In one embodiment, the process also comprises a precleaning-surface activation zone wherein the articles are precleaned and surfaced activated with a cleaning-surface activation solution before painting, and the system and method further comprise sensing the pH of the cleaning-surface activation solution with pH measuring means and generating a pH signal therewith corresponding to real time pH of the cleaning-surface activation solution, and transmitting the pH signal from the pH measuring means to computer-monitor means adaptable for displaying the real time pH of the cleaning-surface activation solution as a pH function over a predetermined period of time. In a further embodiment, the cleaning-surface activation solution is recycled.  
           [0020]    In one embodiment, the predetermined period of time for displaying the pH function also spans at least about 1 hour. In another embodiment, the pH function includes a short term pH function and a long term pH function. In a further embodiment, the short term pH function spans at least about 1 hours and the long term pH function spans at least about 8 hours. In a still further embodiment, the long term pH function spans at least about 12 hours.  
           [0021]    In one embodiment, the process comprises a curing zone wherein the articles after being painted are subjected to an elevated temperature to bond the powder paint particles to the articles, and the system and method further comprise sensing the elevated temperature in the curing zone with temperature sensing means and generating a temperature signal therewith corresponding to real time elevated temperature in the curing zone, and transmitting the temperature signal from the temperature sensing means to computer-monitor means adaptable for displaying the real time temperature of the curing zone as a temperature function over a predetermined period of time.  
           [0022]    In another embodiment, the system and method further comprise sensing the elevated temperature of the curing zone at a plurality of sites in the curing zone with temperature sensing means and generating temperature signals with the temperature sensing means corresponding to real time elevated temperature at each of the sites in the curing zones and transmitting the temperature signals from the temperature sensing means to computer-monitor means adaptable for displaying the real time temperature of each of the sites in the curing zone as temperature functions over a predetermined period of time. In still another embodiment, the computer-monitor means for displaying the temperature functions is also operable for automatically calculating an average temperature corresponding to the average of the real time temperatures at each of the sites, and for displaying the average temperature  
           [0023]    In one embodiment, the predetermined period of time for displaying the temperature function also spans at least about 1 hour. In another embodiment the temperature function includes a short term temperature function and a long term temperature function. In a further embodiment, the short term temperature function spans at least about 1 hour, and the long term temperature function spans at least about 8 hours. In a still further embodiment, the long term temperature function spans at least about 12 hours.  
           [0024]    In one embodiment, the predetermined periods of time for displaying the various functions are all equal to each other so that the short term periods of time are all the same and the long term period of time are all the same. In another embodiment, the real times over which the periods of time span are all the same so that the real times over which the short term periods of time span are all the same, and the real times over which the long term periods of time span are all the same.  
           [0025]    In one embodiment, the computer-monitor means for displaying one function is also the computer-monitor means for displaying all of the other functions. In a further embodiment, the computer-monitor means is also operable for displaying the functions sequentially upon an input command to the computer-monitor means.  
           [0026]    In another embodiment, separate computer-monitor means is provided for displaying each of the various functions so that all functions can be displayed simultaneously.  
           [0027]    In one embodiment, the computer-monitor means is also operable for storing the functions in a memory. In a further embodiment, the system and method further comprise printer means electronically linked to the computer-monitor means, and the printer means is operable for printing the functions from the memory.  
           [0028]    The manager may use the various functions and other information resulting from, and produced by, the monitoring system and method to evaluate the performance of personnel and to discuss with the personnel how performance may be improved. The monitoring system and method also alert the manager if the curing zone is not at the proper temperature so that corrective action may be initiated.  
           [0029]    The records produced by this invention can also be used in soliciting painting jobs from new customers as evidence of the company&#39;s ability to provide good quality control. For example, the viewing of the pH function and printed records of the monitoring system and method enables the manager to provide visual proof to existing and potential customers of the company&#39;s proper article precleaning and surface activation operation. Likewise, the viewing of the monitoring system&#39;s temperature function and printed records thereof enables the manager to provide visual proof to existing and potential customers of the company&#39;s proper curing operation.  
           [0030]    The records of the monitoring system and method also allow the manager to review the historical data of a particular job at a later date if a problem is later discovered, such as insufficient bonding of the powder to the articles.  
           [0031]    The monitoring system and method also enables excellent control of powder inventory, and facilitates “just in time” supply purchases and estimating of powder quantities required for various articles. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0032]    [0032]FIG. 1 is a schematic of a monitoring system and method of this invention added to a flow diagram of a conventional electrostatic powder painting process.  
         [0033]    [0033]FIG. 2 is a line-speed function computer screen display generated by the monitoring system and method showing both a short term line-speed function and a long term line-speed function.  
         [0034]    [0034]FIG. 3 is a powder-weight function and powder-consumption function computer screen display showing examples of a short term power-weight function and a long term powder-weight function, and examples of a short term powder-consumption function and a long term powder-consumption function.  
         [0035]    [0035]FIG. 4 is a pH function computer screen display showing an example of a short term pH function and a long term pH function of the cleaning-activation agent solution used in the pretreatment zone of FIG. 1.  
         [0036]    [0036]FIG. 5 is a temperature function computer screen display showing an example of a short term temperature functions and long term temperature functions at three sites in the curing zone of the process of FIG. 1.  
         [0037]    [0037]FIG. 6 is another temperature functions computer screen display, similar to FIG. 5, except at three additional sites in the curing zone.  
         [0038]    [0038]FIG. 7 is a computer screen display showing for an overview of the powder painting process of FIG. 1 with some important parameters displayed.  
         [0039]    [0039]FIG. 8 is a computer screen display, referred to briefly as the “Calibration Screen” for the monitoring system and method.  
         [0040]    [0040]FIG. 9 is a computer screen display, referred to briefly as the “Powder Inventory Screen” for the monitoring system and method.  
         [0041]    [0041]FIG. 10 is a computer screen display, referred to briefly as the “Reorder Inventory Screen” for the monitoring system and method. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0042]    Referring to FIG. 1, a flow diagram for a conventional electrostatic powder painting process is illustrated. The process involves a number of zones through which a conveyor line  20  travels with articles  21  to be painted carried by the line  20 , usually by hanging therefrom. The conveyor line  20  travels continuously and sequentially through line loading zone  22 , pretreatment zone  23 , drying zone  24 , powder application zone  25 , curing zone  26 , cool down zone  27 , and line unloading zone  28 .  
         [0043]    The articles are loaded on conveyor line  20  in line loading zone  22 . In electrostatic powder painting processes, conveyor line  20  is equipped with a plurality of spaced hooks or other article carrier means  30 , usually referred to as “carts”, which are uniformly spaced apart a predetermined distance  31 , usually about 1 ft. The articles  21  to be painted are merely hung from the carts. For small articles an article, is hung from each cart, while for larger articles an article is hung from every other cart or every third cart.  
         [0044]    Since the unpainted articles generally are received coated with a thin film of protective oil, the oil must be thoroughly removed before the articles can be painted to enable bonding of the powder paint particles to the articles. In the electrostatic powder painting process of FIG. 1, pretreatment zone  23  consists of three stages, namely a combined cleaning-surface activation stage  33 , an initial rinse stage  34 , and a final rinse stage  35 . In the combined cleaning surface activation stage  33  an aqueous solution of a cleaning agent and a surface activation agent, sometimes referred to herein as “cleaning activation agent”, is pumped from tank  37  by pump  38  through a plurality of nozzles  39  and sprayed on articles  21  as they are conveyed through the stage. As the solution drains from the articles the solution is collected and fed by gravity through line  40  back into tank  37  where it is recycled back to combined cleaning-surface activation stage  33 . Periodically the recycled solution must be strengthen by adding fresh cleaning agent-activation agent to tank  37 . Of course, if not desired, it is not necessary to recycle the cleaning-surface activation solution.  
         [0045]    In another electrostatic powder painting process, not shown in the figures, the pretreatment zone comprises five sequential stages namely a cleaning or deoiling stage, a rinse stage, a surface activation stage, a second rinse stage, and a final rinse stage with de-ionized water. Where articles are more difficult to clean and to surface activate, more stages may be used including as many as nine stages. However, the monitoring system and method of this invention can be used with any pretreatment zone regardless of the number of stages.  
         [0046]    Examples of cleaning agents are iron and zinc phosphates cleaning compositions such as ARP-286 of American Research Products, Inc.  
         [0047]    Surface activation agents are effective for conditioning the surface of the articles so that the powder paint particles will adhere to, and bond, to the surface of the articles. Examples of surface activation agents are iron phosphates or zinc phosphates activating compositions used for all metals Other phosphates are also sometimes used.  
         [0048]    Examples of dual purpose cleaning activation agents are also iron or zinc phosphate compositions available from Chemco of Paramount, Calif. and Americoat 1077 available from American Research Products, Inc. which both clean and activate at the same time.  
         [0049]    After leaving the pretreatment zone  23  the articles are dried in a drying zone  24  with hot air blown by fan  42  through heater  43  into drying zone  24 . The temperature of the hot air is generally between 200 and 400° F., and usually about 300° F. Drying of the articles is a function of time and temperatures with higher drying temperatures requiring less time to dry. Because of their shapes some articles drain more slowly than others and, therefore are more difficult to dry. Larger articles usually are more difficult to dry than smaller articles.  
         [0050]    After leaving the drying zone  24 , the articles are conveyed into the powder application zone  25  where the powder is electrostatically sprayed from spray gun  44  onto the articles as they are conveyed through the zone. Spray guns for applying the powder are equipped with a corona wires which charges the particles so that they are attracted to the metal articles carried by the conveyor line. It is recognized in the industry that the conveyor line should be well grounded for good powder-to-article attraction as shown by ground  49 . Powder which overshoot the articles is preferably collected in the bottom of powder application zone  25  and recycled, for example by periodically sweeping up such over spray powder and returning it to delivery container  75  has indicated by dashed line  29 . p After leaving the powder application zone  25  the articles are conveyed into curing zone  26  which is maintained at an elevated temperature effective for bonding the powder to the articles. The temperature for the curing zone is generally between 375 and 400° F., and preferably between 350 and 400° F. with hot air blown by fan  42  through heater  43  into curing zone  26 . The degree of curing or bonding of the powder to the articles is usually a function of time and temperature. The higher the curing temperature the shorter the time required to cure, and the lower the curing temperature the longer the time to cure. For example, at 300° F. the cure time required for a particular articles might be about 10 minutes, while at 400° F. the cure time required may only be about 8 minutes. In the electrostatic powder painting process illustrated in FIG. 1, conveyor line  20  makes four passes  45 ,  46 ,  47  and  48  from one end of curing zone  26  to its other end before exiting the curing zone.  
         [0051]    After leaving the curing zone the articles are carried by conveyor line  20  through a cool down zone  27  and finally to a line unloading zone  28  where they are removed from the conveyor line thereby leaving vacant carts  30 V. The vacant carts are then loaded with more articles and the electrostatic powder painting process continued.  
         [0052]    Conveyor line  20  and the aforementioned processing zones are located within large powder operation room  50  equipped with sliding door  51  through which unpainted articles are received and painted articles are loaded on trucks for delivery to customers or OEM&#39;s.  
         [0053]    This invention provides a system and method for monitoring the electrostatic powder painting process illustrated in FIG. 1, and processes similar thereto, so that the manager does not have to be physically present at all times at the conveyor line in order to be aware of the operations.  
         [0054]    One important aspect of the manager position is to keep the electrostatic powder painting process up and running so that valuable production time is not lost by conveyor line stoppages due to the manager&#39;s unawareness of operational details. Many situations that frequently cause the line to shut down unnecessarily, could be avoided if the manager had a convenient system and method for monitoring the line. Therefore, keeping the line running when it should be running, is a very important concern of a manager and is an objective of this invention.  
         [0055]    Adjacent to room  50  but separated therefrom by wall  52 , is manager&#39;s office  53 . Wall  52  insulates office  53  from heat and sound generated in room  50 . Office  53  contains computer unit  55  which comprises console  565  monitor  57 , key board  58 , mouse  59  and printer  60  which are central to the monitoring system and method of this invention which is more fully described below and illustrated in FIGS.  2 - 10 . Computer unit  553  however, need not be located in an office immediately adjacent to powder operation room  50  but can be in a building physically separated from room  50 . In a further embodiment of this invention, the transmission signals mentioned hereinafter can be transmitted telephonically so that the manager can oversee two or more electrostatic powder painting processes located at different sites, In another embodiment, the management personnel can have a computer terminal linked to the monitoring system and method at their home so that such personnel can review operations from their homes and if necessary consult with the foreman at the line.  
         [0056]    To enable the manager to conveniently monitor conveyor line speed, a motion detector  62  is provided at some convenient point along the line, which in FIG. 1 is at a location between pretreatment zone  23  and drying zone  24 , The motion detector, however, could be located at any point desired along the conveyor line. Motion detector  62  detects each time a cart  30 , or alternatively an article  21 , on the conveyor line  20  passes through the motion detector&#39;s line of sight  63 . When the line of sight is broken, for example by a passing cart, motion detector  62  generates a line-speed signal which is transmitted to console  56 , preferably through junction box  64 . The motion detector is one example of speed sensing means.  
         [0057]    Console  56  convert the line-speed signal into a line-speed function which can be displayed on monitor  57  in real time by suitable input command to computer unit  55 . An example of such line-speed function display is shown in FIG. 2, generally designated by screen numeral  200  and entitled “Line Speed”, wherein the line-speed function includes a short term line-speed function  65  and a long term line-speed function  66 . The line-speed functions preferably have the line speed in FPM (feet per minute) along the ordinate or y-axis and the real time alone the abscissa or x-axis. For both line-speed functions  65  and  66  the ordinate ranges from 0 to 10 FPM. All input commands to computer unit  55  mentioned herein can be entered by key board  58 , and preferably also by pointing at various icons and clicking mouse  59 .  
         [0058]    In FIGS.  2  to  6 , short term functions  65 ,  77 S,  78 S,  89 ,  92 S,  93 S,  94 S,  95 S,  96 S and  97 S span about 1 hour, which in the examples is from about 09:00 to about 10:00. Long term functions  66 ,  77 L,  78 L,  90 ,  92 L,  93 L,  94 L,  95 L,  96 L and  97 L span about 12 hours, which in the examples is from about 22:00 the previous day to about 10:00 of the current day In FIGS.  2  to  6 , the real time is expressed on a 00:00 to 23:59 hour:minute scale.  
         [0059]    As seen in line-speed functions  65  and  66  of example of FIG. 2, the conveyor line had been running at about 9 FPM until about 09:30 of the current day at which time the line was stopped. If stopping the line was unexpected, the manager can immediately interrupt his present activities, investigate and take steps to minimize the down time.  
         [0060]    Other information and data valuable to the manager can also be simultaneously displayed with the line-speed functions as alpha-numeric insets. Referring to FIG. 2, examples of such insets are:  
         [0061]    Up Time, expressed in hrs., box  68 ,  
         [0062]    Up Time, expressed in % of total elapsed time since the start of the run, box  69 ,  
         [0063]    Down Time, expressed in hrs., box  70 ,  
         [0064]    Down Time, expressed in % of total elapsed time since the start of the run, box  71 , and  
         [0065]    Line Speed, expressed in FPM, box  72 .  
         [0066]    A frequent cause of unnecessary conveyor line shut down is down-time spent for refilling delivery container  75  with powder. Spray gun  44  receives powder from delivery container  75  through hose  74 . Usually, in all modern electrostatic powder painting processes the delivery container can be refilled with powder without stopping spray painting or the conveyor line.  
         [0067]    In the embodiment shown in FIG. 1, delivery container  75  containing the powder is positioned on a weight scale  76  which generates a container weight signal corresponding to the combined weight of the delivery container and powder therein. A weight scale is one example of powder amount sensing means. The container weight signal is then transmitted from the scale, preferably through junction box  64 , to console  56 .  
         [0068]    Other examples of powder amount sensing means are powder volume measuring apparatuses, and powder metering apparatuses, rotary-vane metering valves for powders, radiation transmission meters that pass a beam of radiation through a powder-flow-through conduit which is transparent to the particular radiation used and detect the level of radiation on the opposite side of the conduit, and powder capacitance apparatuses such as capacitance continuous level probe transmitters having an electronic amplifier the signal of which is associated with powder amount in the powder supply tank or hopper. With any of such powder sensing means the weight signal is then transmitted from the scale, preferably through junction box  645  to console  56 .  
         [0069]    Computer unit  55  can display the real time combined weight of the delivery container and powder as a container weight function on monitor  57  upon an input command to computer unit. An example of such line container weight function display is shown in FIG. 3, generally designated by screen numeral  300  and entitled “Powder Trends  0 - 100 ”, wherein the container weight function includes a short term container weight function  77 S and a long term container weight function  77 L. These container weight functions preferably have the weight along the ordinate or y-axis and the real time along the abscissa or x-axis. If desired, the container weight function can be displayed as the net weight of the powder with the tare weight of the delivery container automatically subtracted from the combined weight by the computer unit.  
         [0070]    In FIG  3 , short and long term container weight functions  77 S and  77 L are shown spanning the same period of time as that shown in FIG. 2 for short and long line-speed functions,  65  and  66 , respectively. For both container weight functions  77 S and  77 L, the ordinate ranges from 0 to 100 lbs. in FIG. 3.  
         [0071]    As illustrated by container weight functions  77 S and  77 L, the combined weight of the delivery container and powder therein decreased at about a constant downward slope with time, indicating a steady rate of powder consumption until various times when the delivery container was recharged with more powder.  
         [0072]    If the manager notices that the container weight function is getting very low, he can interrupt his present activities and remind the operators to recharge the delivery container thereby avoiding stopping the line to refill the delivery container with more powder. An alarm  79  is also provided in operations room  50  to sound when the powder level in delivery container  75  is low. To simplify the long term graph only the last hour of container weight function  77 L is shown.  
         [0073]    Computer unit  55  can also display the real time total weight of powder used for a particular job as powder-used or powder-consumption functions. Examples of such powder-consumption functions are shown in FIG. 3, wherein the function includes short term powder-consumption function  78 S, and long term powder-consumption function  78 L. Powder-consumption functions  77 S and  78 L are superimposed on container weight functions  77 S and  77 L and are retrieved simultaneously with those functions with screen  300 . As illustrated in FIG. 3, the total powder weight used increased at about a constant upward slope with time, indicating a steady rate of powder consumption, until various times when the powder-consumption function was rezeroed to prevent it from running of the graph.  
         [0074]    Other information and data valuable to the manager can also be displayed with the container weight functions as alpha-numeric insets. Referring to FIG. 3, examples of such insets are:  
         [0075]    The current combined delivery container and powder weight therein, in lbs., box  80 ,  
         [0076]    The total powder weight used in the last run, in lbs., box  81 ,  
         [0077]    The total powder weight used in the current run, in lbs., box  82 , and  
         [0078]    Powder Identifier, box  83 .  
         [0079]    A key pad  86 , preferably located near the delivery container  75 , is used by operating personnel to enter a Powder Identifier code. The key pad transmits a corresponding powder identifier signal, preferably through junction box  64 , to console  56 . Computer unit  55  also displays the Powder Identifier on monitor simultaneously with the container weight and powder-consumption functions as box  83  in FIG. 3. This information is important to the manager in order to catch as soon as possible a mistake in the paint being sprayed. It is very costly to discover after a job has been completed that the wrong paint was used.  
         [0080]    Master icon  136  is replaced with icons  136 A and  136 B in FIG. 3. Icon  136 A is used for changing the ordinate scale from 0-100 lbs. to 0-200 lbs. and icon  136 B for changing the ordinate scale from 0-100 lbs. to 0-300 lbs. upon a point and click command from mouse  59 .  
         [0081]    Maintaining the proper concentration of the cleaning-surface activation agent in the combined cleaning-surface activation stage  33  is critical to the bonding of the powder to the articles. If the concentration of the cleaning-activation agent is too low the oil film will not be removed and the surface of the articles will not be adequately activated for bonding of the powder to the articles. In the past it has been the practice to add a predetermined amount of cleaning-activation agent to tank  37  about every three hours to maintain an effective concentration of the cleaning-activation agent.  
         [0082]    The pH of the cleaning-activation agent in tank  37  is a function of the concentration of cleaning-activation agent. When using the Chemco or ARP-286 and Americoat 1077 cleaning-activation agents, their concentration should be maintained in the range of from about 2 to about 5%, which corresponds to a pH range of from about 2 to about 4.8. In this invention a pH sensor  88  is installed in tank  37  to sense the pH of the cleaning-activation agent solution therein. The PH sensor transmits a pH signal to console  56 , preferably through junction box  64 . A pH sensor is an example of pH measuring means.  
         [0083]    Console  56  convert the pH signal into a pH function which can be displayed on monitor  57  in real time by suitable input command to computer unit  55 . An example of such pH function display is shown in FIG. 4, generally designated by screen numeral  400  and entitled “pH”, wherein the pH function includes a short term pH function  89  and a long term pH function  90 . The PH functions preferably have the pH value along the ordinate or y-axis and the real time along the abscissa or x-axis. The current pH value is shown in box  91 .  
         [0084]    In FIG. 4, short term pH function  89  and long term pH function  90  span the same period of time as that shown in FIG. 2 for short and long line-speed functions  65  and  66 , respectively. For both pH functions  89  and  90 , the ordinate ranges from 0 to 14 pH values. However, because of the condensed ordinate scale with long term pH function  90  the curve appears as a straight line since the variation in pH when using Chemco or ARP-286 and Americoat 1077 as the cleaning activation agent, runs normally between 4.3. and 4.5.  
         [0085]    Insuring that the curing zone is maintained at the proper temperature is also provided for in the monitoring system and method of this invention by installing thermocouples to sense the temperature at several sites in the curing zone. With reference to FIG. 1, six thermocouples,  92 ,  93 ,  94 ,  95 ,  96  and  97  are shown in curing zone  26 . Each thermocouple generates a temperature signal which is transmitted to console  56 , preferably through junction box  64 . A thermocouple is an example of temperature sensing means.  
         [0086]    Console  56  convert the temperature signals into temperature functions which can be displayed on monitor  57  in real time by suitable input command to computer unit  55 . An example of such temperature function display is shown in FIG. 5. Generally designated by screen numeral  500  and entitled “Temperature Zones  1 - 3 ”, for thermocouples  92 ,  93  and  94 , and FIG. 6, generally designated by screen numeral  600  and entitled “Temperature Zones  4 - 6 ”, for thermocouples  95 ,  96  and  97 . The temperature functions includes a short term temperature function and a long term temperature function for each thermocouple site. Short term temperature functions  92 S,  93 S,  94 S,  95 S,  96 S and  97 S receive their input from thermocouples  92 ,  93 ,  94 ,  95 ,  96  and  97 , respectively. Long term temperature functions  92 L,  93 L,  94 L,  95 L,  96 L and  97 L also receive their input from thermocouples  92 ,  93 ,  94 ,  95 ,  96  and  97  respectively. The scale for the temperature functions preferably have temperature in of along the ordinate or y-axis, and the real time alone the abscissa or x-axis. For all temperature functions in FIGS. 5 and 6, the ordinate ranges from about 0° F. to about 500° F.  
         [0087]    Other information and data valuable to the manager can also be simultaneously displayed with the temperature functions as alpha-numeric insets. Referring to FIGS. 5 and 6, examples of such insets are:  
         [0088]    Site  1 , temperature expressed in ° F., box  100 ,  
         [0089]    Site  2 , temperature expressed in ° F., box  101 ,  
         [0090]    Site  3 , temperature expressed in ° F., box  102 ,  
         [0091]    Site  4 , temperature expressed in ° F., box  103 ,  
         [0092]    Site  5 , temperature expressed in ° F., box  104 , and  
         [0093]    Site  6 , temperature expressed in ° F., box  105 ,  
         [0094]    The average temperature of the six sites expressed in ° F., box  106 .  
         [0095]    In FIG. 5, master icon  133  is replaced with icon  133 A for accessing FIG. 6. Similarly in FIG. 6, master icon  133  is replaced with icon  133 B for accessing FIG. 5.  
         [0096]    If desired, this monitoring system and method can also provide a display similar to FIG. 5 for monitoring the temperature of drying zone  24 .  
         [0097]    A most informative display generated by the monitoring system and method of this invention is that of an overview of the entire powder painting process an example of which is shown in FIG. 7, generally designated by screen numeral  700  and entitled “Overview”. Critical conditions occurring in the electrostatic powder painting process are displayed as alphanumeric insets positioned adjacent a simulated conveyor line in process diagram showing the various zones The insets in FIG. 7 are as follows:  
         [0098]    The current combined delivery container and powder therein weight in lbs., box  110 ,  
         [0099]    The total powder used or consumed in the current run, in lbs., box  111 ,  
         [0100]    The average temperature of the six sites where thermocouples  92 ,  93 ,  94 ,  95 ,  96  and  97  are located, expressed in ° F., box  112 ,  
         [0101]    Site  1  temperature here thermocouple  92  is located, expressed in ° F., box  113 ,  
         [0102]    Site  2  temperature, where thermocouple  93  is located, expressed in ° F., box  114 ,  
         [0103]    Site  3  temperature, where thermocouple  94  is located, expressed in ° F., box  115 ,  
         [0104]    Site  4  temperature, where thermocouple  95  is located, expressed in ° F., box  116 ,  
         [0105]    Site  5  temperature, where thermocouple  96  is located, expressed in ° F., box  117 ,  
         [0106]    Site  6  temperature, where thermocouple  97  is located, expressed in ° F., box  118 ,  
         [0107]    The pH of the cleaning-activation agent solution in tank  37 , box  119 , and  
         [0108]    Line Speed expressed in FPM, box  120 .  
         [0109]    The manager while in office  53  may leave either the overview display, illustrated by FIG. 7, or the line-speed function displays illustrated by FIG. 23 on monitor  57  when not viewing one of the other displays, so that with a glance from his desk he can immediate ascertain if there is any difficulty in the electrostatic powder painting process.  
         [0110]    The computer unit enables each display to be retrieved quickly, through key board command, or by pointing and clicking to Master Icons displayed on monitor  57 . Examples of such Master Icons and their labels are:  
                                       Master Icon   Element No.   Retrieves Display Similar To                   Line Speed   130           Powder Trends   136           pH   132           ° F. Sites   133           Overview   134           Calibrate   135           Powder Inventory   131           Prt Scrn   137   Prints the current screen                  
 
         [0111]    Positioning the mouse arrow on the Print Screen icon  137  and clicking mouse  59  causes computer unit  55  to instruct printer  60  to print the screen currently displayed on monitor  57 .  
         [0112]    The monitoring system and method of this invention can also be used to display and input, other values and names to the computer unit  55 . For example, the screen shown in FIG. 8, generally designated by screen numeral  800  and entitled “Calibration”, refers to the following Instructions and Set Points:  
                                                   Instruction   Set Point, or Icon                           Enter new Line Speed if different   Line speed FPM;           from actual speed.   Set Point 141           To calibrate use Set TARE to zero   Set TARE; Icon 142           the scale, then using a known weight   Scale Weight in lbs;           enter new Powder Scale Weight if   Set Point 143           different from known weight.           Enable Up Time and Down Time during           these hours:           Daily Start Time.   Set Point 144           Daily Stop Time.   Set Point 145           Low Powder Alarm LBS.   Set Point 146           Inventory Discrepancy %.   Set Point 147                      
 
         [0113]    Calibration Screen  800  shown in FIG. 8 is used by management to set the parameters for the monitoring system and method. The parameters may vary from company to company. Once the parameters are set they serve as a basis for interpreting the information generated by the monitoring system and method.  
         [0114]    Set Point  141  is used to set the line speed, which is usually set when the monitoring system and method is installed and usually does not need to be reset.  
         [0115]    Icon  142  is used for adjusting the weight reading of scale  76  with a known weight on the scale, to the weight of the known weight, by entering the known weight in box  143 , thereby insuring that future scale weights reported by the monitoring system and method are accurate. Set Point  143  is reset frequently as the powder hopper or delivery container  75  is changed.  
         [0116]    Set Point  144  and Set Point  145  are used to set the up and down times. The up and down times or operating hours are adjusted as needed to correspond to the nominal production hours. For example, for two shifts the up and down times might be set for 00:00 (midnight) the start of the first shift and 16:00 the end of the second shift. The actual operating hours may vary from company to company.  
         [0117]    Set Point  146  is used to set the alarm for a predetermined low level of powder in delivery container  75 . The set point for this alarm is up to the discretion of the manager to decide at what weight the alarm should sound.  
         [0118]    Set Point  147  is used to set the maximum percentage variance in powder inventory between the value generated by the monitoring system and method and the value entered periodically by the operator or management. If the amount enter by management exceeds the set point % discrepancy box  147 , then the monitoring system and method will generate a prompt signal which pops up the Reorder Inventory screen of FIG. 10. The prompt signal may be removed from FIG. 10 upon recognition by management which should occur only after the particular powder ID is re-inventoried and the discrepancy resolved. The Inventory Discrepancy % box  147 , may vary from company to company.  
         [0119]    Set Points  141 ,  142 ,  143 ,  144 ,  145 ,  146  and  147  are the values entered and chanced by management as required for monitoring the electrostatic powder painting process.  
         [0120]    Preferably access to FIG. 8 requires a password, since prevention of unaccounted loss of powder is one of the objectives and embodiments of the monitoring system and method.  
         [0121]    The screen display  900 , shown in FIG. 9, referred to as “Powder Inventory”, is produced by the monitoring system and method for each powder inventoried. The following Identifiers, Set Points, Current Values and Icons are displayed in FIG. 9:  
                                                       Identifier, or Set Point, or           Instruction   Current Yalue or Icon                           Name   Identifier 150           ID#   Identifier 151           Description   Identifier 152           Time Range, in minutes   Set Point 153L and Set Point 153H           Temperature Range, in ° F.   Set Point 154L and Set Point 154H           Current Inventory   Current Value 155           Est.   Set Point 156           % Discrepancy   Current Value 157           Reorder at lbs.   Set Point 158           Find Item   Icon 159           Add Item   Icon 160           Delete Item   Icon 161           Adj. Weight   Icon 162           Image of a Scroll Bar   Icon 163           Save   Icon 164           Exit   Icon 165           Print Inventory, Normal   Icon 166           Print Inventory, Short   Icon 167           Total Items   Current Value 168           Total, in Lbs.   Current Value 169           Reorder   Icon 170-for accessing FIG. 10           Prt Scrn   Icon 137                      
 
         [0122]    Element  150 ,  151  and  152  are identifiers for the powder in question, which by pointing to any one of the three and typing in the number or name of the powder, or scrolling to such with up/down scroll bar icon  163 , produces a screen of information on the particular powder.  
         [0123]    Elements  153 L and  153 H are set points for low and high line speeds which control the time the articles spend in curing zone  26 . Elements  154 L and  154 H are set points for low and high temperature settings for curing zone  26  for the particular powder in question.  
         [0124]    Element  155  is the weight of the current inventory of the powder in question. Element  156  is the physical inventory estimated by the powder technician and inputted to the monitoring system and method by the powder technician through key pad  86 . Element  157 , entitled % Discrepancy on screen  900 , is the current value of the difference between the current inventory value stored in the memory of monitoring system and method and the estimated physical inventory value expressed as %. The powder technician deletes or subtracts powder from the physical inventory box  156 , as he removes it from inventory.  
         [0125]    Element  158  is the minimum amount of powder required to be in inventory for a particular powder, which can vary from powder to powder. The monitoring system and method generate prompt screen  1000  whenever the current inventory reaches the set point value shown in box  158 .  
         [0126]    Elements  159 ,  160 ,  161 ,  162 ,  163 ,  164 ,  165 ,  166 ,  167 ,  170  and  137  are icons for various computer functions activated by pointing at the particular icon and clicking mouse  59 . Element  159  allows the user to find a powder from the list by typing in the name rather than scrolling through the entire list using scroll bar  163 . Element  160  is used when entering the name, ID# and description of a new powder. Element  161  deletes an item from the list. Element  162  allows the user to adjust the inventory by adding just received powder to the inventory or making other corrections to the inventory. Element  163  is used for scrolling through the powder inventory list. Element  164  saves the information just entered into the monitoring system and method. Element  165  exits the screen. Elements  166  and  167  prints a short list or normal list respectively of the items in inventory.  
         [0127]    Element  168  is the total number of powders in inventory.  
         [0128]    Element  169  is the current total weight on hand of the particular powder shown in identifiers  150 ,  151  and  152 .  
         [0129]    Element  170  accesses Reorder Inventory screen  1000  describe next.  
         [0130]    Whenever a particular powder or other inventory item runs low, computer unit  55  will cause a screen, shown in FIG. 10, generally designated by numeral  1000  and entitled “Reorder Inventory”, to pop up after a predetermined period of times e.g. 20 minutes, on monitor  57 . The following Identifiers Set Points, Current Values and Icons are displayed in FIG. 10:  
                                                       Identifier, or Set Point,           Instruction   or Current Value or Icon                           ID#   Identifier column 180           Invent., Weight Lbs.   Current Value column 181           Estim., Weight Lbs.,   Set Point column 182           RED indicates discrepancy           Name, Click to Acknowledge   Identifier column 183           Description   Identifier column 184           Exit   Icon 185           Prt Scrn   Icon 137                      
 
         [0131]    Columns  180 ,  183  and  184  are the ID#, name and description, respectively, of the powder or powders for which the monitoring system and method think there may be an inventory problem.  
         [0132]    Column  181  indicates the current inventory which the monitoring system and method think is on hand. The number(s) appearing in column  181  are calculated by computer unit  55  by subtracting the powder from the inventory as it is removed from delivery container  75 . Column  182  shows the physical inventory which the powder technician has estimated and entered into the monitoring system and method. Only those powders for which a potential problem has been identified appear on screen  1000  of FIG. 10.  
         [0133]    Whenever FIG. 10 pops up, it remains on monitor  57  until “acknowledged”, usually performed by pointing and clicking to exit icon  165 .  
         [0134]    Thus screen  1000  of FIG. 10 is a prompting device which is used to tell management, when a potential problem has been identified by the monitoring system and method. For example, if the difference between the current inventory that the monitoring system and method think is in stock, shown in column  181 , and the physical inventory “set point” that the powder technician believes is on hand and had entered in the monitoring system and method shown in column  182 , exceeds the set point for % Discrepancy shown in box  147  of FIG. 8, then the monitoring system and method prompt the viewer by popping up FIG. 10.  
         [0135]    When a powder is entered into or added to the inventory the powder technician enters the data in the monitoring system and method through box  162  of screen  900  of FIG. 9. FIG. 9 also shows the Set Point, box  158 , for ordering more powder. The set point can vary from one powder to another. When the inventory falls to the amount shown in box  158  the powder will be automatically listed on the Reorder Inventory screen  1000  of FIG. 10 and the monitoring system and method will cause FIG. 10 to pop up after the predetermined period of time, e.g. 20 minutes, thereby alerting management to reorder the particular powder in question to increase inventory of the powder in question above the set point value shown in box  158 .  
         [0136]    Therefore, the monitoring system and method will cause screen  1000  of FIG. 10 to pop up (i) whenever the % discrepancy set point shown in box  147  is exceeded, or (ii) whenever the “Current Inventory” shown in box  155  falls to the “Reorder at” value shown in box  158 . Whenever the cause of concern (i) occurs management will have the powder technician redo the physical inventory to see whether it is correct or the current inventory shown in box  155  is correct.  
         [0137]    In the example shown in FIG. 10, out of 42 types of powder on hand, box  168  the monitoring system and method has identified only two powders for which the monitoring system and method believe there is a potential inventory problem. The 0&#39;s in columns  180  and  181  indicate no additional powder problems have been identified by the monitoring system and method.  
         [0138]    In general, computer unit  55  can also save the various functions and displays in the memory of its console, and produce a print out thereof upon an input command to the computer unit and/or automatically at predetermined times.  
         [0139]    Although the process is illustrated for an electrostatic powder paint system and method, it should be understood that the principles of system and method can be used for electrostatic liquid system and method and even for non-electrostatic liquid system and method.  
         [0140]    While the preferred embodiments of the present invention have been described various changes and modifications may be made thereto without departing from the spirit of the invention and the scope of the appended claims. The present disclosure and embodiments of this invention described herein are for purposes of illustration and example and modifications and improvements may be made thereto without departing from the spirit of the invention or from the scope of the claims. The claims, therefore, are to be accorded a range of equivalents commensurate in scope with the advances made over the art.