Abstract:
A system 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 &#34;powder&#34;, applied to the articles, the system senses the 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 senses 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 senses 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 senses 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 time, e.g. 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 allows 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 
     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 
     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. 
     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 to 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. 
     Therefore, there is a need for a system for monitoring electrostatic powder painting processes that allows 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 
     The monitoring systems of this invention allows 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 prompts the manager to investigate. 
     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 records, discussions with shift supervisors, inventory review, ordering of supplies, and planning schedules and other business activities. 
     Due to the nature of the powder paint particles, hereinafter referred to as &#34;powder&#34;, 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 in the operations part of the business, where clothing can be easily soiled, facilitates maintaining a clean dress appearance. 
     In general, the monitoring systems 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. 
     The manager may also use the information resulting from and produced by the monitoring system 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 records resulting from the monitoring system 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. 
     Accordingly, there is provided by the principles of this invention a system 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. 
     In one embodiment, the system comprises 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 weight of the powder paint particles in the powder delivery means with scale means and generating a powder or paint weight signal therewith corresponding to real time weight of the powder paint particles in the powder delivery means, and transmitting the powder-weight signal from the scale 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. 
     In another embodiment, the computer-monitor means for displaying the powder-weight function is also adaptable for converting the powder-weight 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 embodiment, 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. 
     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 includes sensing the weight of the delivery container and powder paint particles therein with the scale means and generating a powder-weight 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 function, and for displaying the second powder-weight function over a predetermined period of time. 
     In one embodiment, the predetermined period of time for displaying the powder-weight function spans at least about 1 hour. In another embodiment, 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 embodiment, the long term powder-weight function spans at least about 12 hours. 
     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 signal reaches the predetermined low weight parameter. In this embodiment, 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. 
     In another embodiment, the system further comprises a data input device proximate the conveyor line for imputing a paint identifier code to the computer-monitor means for displaying the powder-weight function. 
     In one embodiment, the system comprises 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. 
     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. 
     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 further comprises 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. 
     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 hour, 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. 
     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 further comprises 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 
     In another embodiment, the system further comprises 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 zone, 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 
     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. 
     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. 
     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. 
     In another embodiment, separate computer-monitor means is provided for displaying each of the various functions so that all functions can be displayed simultaneously. 
     In one embodiment, the computer-monitor means is also operable for storing the functions in a memory. In a further embodiment, the system further comprises printer means electronically linked to the computer-monitor means, and the printer means is operable for printing the functions from the memory. 
     The manager may use the various functions and other information resulting from and produced by the monitoring system to evaluate the performance of personnel and to discuss with the personnel how performance may be improved. The monitoring system also alerts the manager if the curing zone is not at the proper temperature so that corrective action may be initiated. 
     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 monitoring system&#39;s pH function and printed records thereof 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. 
     The monitoring system records also allows 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. 
     The monitoring system also enables excellent control of powder inventory, and facilitates &#34;just in time&#34; supply purchases and estimating of powder quantities required for various articles. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic of a monitoring system of this invention added to a flow diagram of a conventional electrostatic powder painting process. 
     FIG. 2 is a line-speed function computer screen display generated by the monitoring system showing both a short term line-speed function and a long term line-speed function. 
     FIG. 3 is a powder-weight function and powder-consumption function computer screen display showing examples of a short term powder-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. 
     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. 
     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. 
     FIG. 6 is another temperature functions computer screen display, similar to FIG. 5, except at three additional sites in the curing zone. 
     FIG. 7 is a computer screen display showing for an overview of the powder painting process of FIG. 1 with some important parameters displayed. 
     FIG. 8 is a computer screen display, referred to briefly as the &#34;Calibration Screen&#34; for the monitoring system. 
     FIG. 9 is a computer screen display, referred to briefly as the &#34;Powder Inventory Screen&#34; for the monitoring system. 
     FIG. 10 is a computer screen display, referred to briefly as the &#34;Reorder Inventory Screen&#34; for the monitoring system. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     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. 
     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 &#34;carts&#34;, 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. 
     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 &#34;cleaning-activation agent&#34;, 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. 
     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 of this invention can be used with any pretreatment zone regardless of the number of stages. 
     Examples of cleaning agents are ARP-286. The surface activation agent is 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 phosphate or zinc phosphate used for all metals. Other phosphates are also sometimes used. Examples of cleaning-activation agents are Americoat 1077 purchased from American Research Products, Inc. 
     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 temperature, with higher drying temperatures requiring less time to dry. Because of their shape, 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. 
     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. 
     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. 
     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 30V. The vacant carts are then loaded with more articles and the electrostatic powder painting process continued. 
     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. 
     This invention provides a monitoring system 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. 
     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 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. 
     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 56, monitor 57, key board 58, mouse 59 and printer 60 which are central to the monitoring system of this invention which is more fully described below and illustrated in FIGS. 2-10. Computer unit 55, 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 at their home so that such personnel can review operations from their homes and if necessary consult with the foreman at the line. 
     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. 
     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 &#34;Line Speed&#34;, 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 along 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. 
     In FIGS. 2 to 6, short term functions 65, 77S, 78S, 89, 92S, 93S, 94S, 95S, 96S and 97S span about 1 hour, which in the examples is from about 09:00 to about 10:00. Long term functions 66, 77L, 78L, 90, 92L, 93L, 94L, 95L, 96L and 97L 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. 
     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. 
     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: 
     Up Time, expressed in hrs., box 68, 
     Up Time, expressed in % of total elapsed time since the start of the run, box 69, 
     Down Time, expressed in hrs., box 70, 
     Down Time, expressed in % of total elapsed time since the start of the run, box 71, and 
     Line Speed, expressed in FPM, box 72. 
     A frequent cause of unnecessary conveyor line shut down is down-time spent for refiling 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 refiled with powder without stopping spray painting or the conveyor line. 
     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 scale means. The container weight signal is then transmitted from the scale, preferably through junction box 64, to console 56. 
     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 &#34;Powder Trends 0-100&#34;, wherein the container weight function includes a short term container weight function 77S and a long term container weight function 77L. 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. 
     In FIG. 3, short and long term container weight functions 77S and 77L 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 77S and 77L, the ordinate ranges from 0 to 100 lbs. in FIG. 3. 
     As illustrated by container weight functions 77S and 77L, 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. 
     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 77L is shown. 
     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 78S, and long term powder-consumption function 78L. Powder-consumption functions 78S and 78L are superimposed on container weight functions 77S and 77L 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 off the graph. 
     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: 
     The current combined delivery container and powder weight therein, in lbs., box 80, 
     The total powder weight used in the last run, in lbs., box 81, 
     The total powder weight used in the current run, in lbs., box 82, and 
     Powder Identifier, box 83. 
     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. 
     Master icon 136 is replaced with icons 136A and 136B in FIG. 3. Icon 136A is used for changing the ordinate scale from 0-100 lbs. to 0-200 lbs. and icon 136B for changing the ordinate scale from 0-100 lbs. to 0-300 lbs. upon a point and click command from mouse 59. 
     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. 
     The pH of the cleaning-activation agent in tank 37 is a function of the concentration of cleaning-activation agent. When using ARP-286 and Americoat 1077 as the cleaning-activation agent, its 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. 
     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 &#34;pH&#34;, 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. 
     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 ARP-286 and Americoat 1077 as the cleaning-activation agent, runs normally between 4.3. and 4.5. 
     Insuring that the curing zone is maintained at the proper temperature is also provided for in the monitoring system 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. 
     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 &#34;Temperature Zones 1-3&#34;, for thermocouples 92, 93 and 94, and FIG. 6, generally designated by screen numeral 600 and entitled &#34;Temperature Zones 4-6&#34;, 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 92S, 93S, 94S, 95S, 96S and 97S receive their input from thermocouples 92, 93, 94, 95, 96 and 97, respectively. Long term temperature functions 92L, 93L, 94L, 95L, 96L and 97L also receive their input from thermocouples 92, 93, 94, 95, 96 and 97, respectively. The scale for the temperature functions preferably have temperature in ° F. along the ordinate or y-axis, and the real time along 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. 
     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: 
     Site 1, temperature expressed in ° F., box 100, 
     Site 2, temperature expressed in ° F., box 101, 
     Site 3, temperature expressed in ° F., box 102, 
     Site 4, temperature expressed in ° F., box 103, 
     Site 5, temperature expressed in ° F., box 104, and 
     Site 6, temperature expressed in ° F., box 105. 
     The average temperature of the six sites expressed, in ° F., box 106. 
     In FIG. 5, master icon 133 is replaced with icon 133A for accessing FIG. 6. Similarly in FIG. 6, master icon 133 is replaced with icon 133B for accessing FIG. 5. 
     If desired, this monitoring system can also provide a display similar to FIG. 5 for monitoring the temperature of drying zone 24. 
     A most informative display generated by the monitoring system 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 &#34;Overview&#34;. Critical conditions occurring in the electrostatic powder painting process are displayed as alpha-numeric insets positioned adjacent a simulated conveyor line in process diagram showing the various zones. The insets in FIG. 7 are as follows: 
     The current combined delivery container and powder therein weight in lbs., box 110, 
     The total powder used or consumed in the current run, in lbs., box 111, 
     The average temperature of the six sites where thermocouples 92, 93, 94, 95, 96 and 97 are located, expressed in ° F., box 112, 
     Site 1 temperature, where thermocouple 92 is located, expressed in ° F., box 113, 
     Site 2 temperature, where thermocouple 93 is located, expressed in ° F., box 114, 
     Site 3 temperature, where thermocouple 94 is located, expressed in ° F., box 115, 
     Site 4 temperature, where thermocouple 95 is located, expressed in ° F., box 116, 
     Site 5 temperature, where thermocouple 96 is located, expressed in ° F., box 117, 
     Site 6 temperature, where thermocouple 97 is located, expressed in ° F., box 118, 
     The pH of the cleaning-activation agent solution in tank 37, box 119, and 
     Line Speed expressed in FPM, box 120. 
     The manager while in office 53 may leave either the overview display, illustrated by FIG. 7, or the line-speed function display, illustrated by FIG. 2, 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. 
     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                             FIG. 2Powder Trends            136                        FIG. 3pH                                          FIG. 4°F. Sites             133                       FIG. 5Overview              134                                       FIG. 7Calibrate            135                                       FIG. 8Powder Inventory         131                           FIG. 9Prt Scrn              137                              Prints the current screen______________________________________ 
    
     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. 
     The monitoring system 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 &#34;Calibration&#34;, 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 141To calibrate  use Set TARE to zerothe scale, then using a known                   Set TARE; Icon 142weight enter new Powder Scaleweight  if different  from known                   Scale Weight in lbs;weight.                                           Set Point 143Enable Up Time and  Down  Timeduring these hours:Daily Start Time.                         Set Point 144Daily Stop Time.                           Set Point 145Low Powder Alarm LBS.                    Set Point 146Inventory Discrepancy %                                  Set Point 147______________________________________ 
    
     Calibration Screen 800 shown in FIG. 8 is used by management to set the parameters for the monitoring system. 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. 
     Set Point 141 is used to set the line speed, which is usually set when the monitoring system is installed and usually does not need to be set. 
     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 are accurate. Set Point 143 is reset frequently as the powder hopper or delivery container 75 is changed. 
     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. 
     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. 
     Set Point 147 is used to set the maximum percentage variance in powder inventory between the value generated by the monitoring system 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 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. 
     Set Points 141, 142, 143, 144, 145, 146 and 147 are the values entered and changed by management as required for monitoring the electrostatic powder painting process. 
     Preferably, access to FIG. 8 requires a password, since prevention of unaccounted loss of powder is one of the embodiments of the monitoring system. 
     The screen display 900, shown in FIG. 9, referred to as &#34;Powder Inventory&#34;, is produced by the monitoring system for each powder inventoried. The following Identifiers, Set Points, Current Values and Icons are displayed in FIG. 9: 
     
         ______________________________________            Identifier, or Set Point, orInstruction                  Current Value or Icon______________________________________ Name                                   Identifier 150ID#                                     Identifier 151Description                         Identifier 152Time Range, in minutes                    Set Point 153L and  Set Point 153HTemperature Range in ° F.               Set Point 154L and  Set Point 154HCurrent Inventory                         Current Value 155Est                                         Set Point 156% Discrepancy                     Current Value 157Reorder at lbs                   Set Point 158Find Item                             Icon 159Add Item                               Icon 160Delete Item                         Icon 161Adj. Weight                         Icon 162Image of a Scroll Bar                     Icon 163Save                                       Icon 164Exit                                       Icon 165Print Inventory, Normal                   Icon 166Print Inventory, Short                    Icon 167Total Items                         Current Value 168Total, in Lbs.                    Current Value 169Reorder                                 Icon 170--for accessing FIG. 10Prt Scrn                               Icon 137______________________________________ 
    
     Element 150, 151 and 152 are identifiers for the powder in questions 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. 
     Elements 153L and 153H are set points for low and high line speeds which control the time the articles spend in curing zone 26. Elements 154L and 154H are set points for low and high temperature settings for curing zone 26 for the particular powder in question. 
     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 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 the estimated physical inventory value expressed as %. The powder technician deletes powder from the physical inventory, box 156, as he removes it from inventory. 
     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 generates prompt screen 1000 whenever the current inventory reaches the set point value shown in box 158. 
     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. Element 165 exits the screen. Elements 166 and 167 prints a short list or normal list, respectively, of the items in inventory. 
     Element 168 is the total number of powders in inventory. 
     Element 169 is the current total weight on hand of the particular powder shown in identifiers 150, 151 and 152. 
     Element 170 accesses Reorder Inventory screen 1000 describe next. 
     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 &#34;Reorder Inventory&#34;, to pop up after a predetermined period of time, e.g. 20 minutes, on monitor 57. The following Identifiers, Set Points, Current Values and Icons are displayed in FIG. 10: 
     
         ______________________________________                                  Identifier, or Set PointInstruction                             or Current Value or______________________________________              Icon ID#                                      Identifier column 180Invent., Weight Lbs.                          Current Value column 181Estim., Weight Lbs.,RED indicates discrepancy                   Set Point column 182Name, Click to Acknowledge                    Identifier column 183Description                             Identifier column 184Exit                                           Icon 185Prt Scrn                                   Icon 137______________________________________ 
    
     Columns 180, 183 and 184 are the ID#, name and description, respectively, of the powder or powders for which the monitoring system thinks there may be an inventory problem. 
     Column 181 indicates the current inventory which the monitoring system thinks 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. Only those powders for which a potential problem has been identified appear on screen 1000 of FIG. 10. 
     Whenever FIG. 10 pops up, it remains on monitor 57 until &#34;acknowledged&#34;, usually performed by pointing and clicking to exit icon 165. 
     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. For example, if the difference between the current inventory that the monitoring system thinks is in stock, shown in column 181, and the physical inventory &#34;set point&#34; that the powder technician believes is on hand and had entered in the monitoring system, shown in column 182, exceeds the set point for % Discrepancy shown in box 147 of FIG. 8, then the monitoring system prompts the viewer by popping up FIG. 10. 
     When a powder is entered into or added to the inventory, the powder technician enters the data in the monitoring system 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 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. 
     Therefore, the monitoring system 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 &#34;Current Inventory&#34; shown in box 155 falls to the &#34;Reorder at&#34; 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. 
     In the example shown in FIG. 10, out of 42 types of powder on hand, box 168, the monitoring system has identified only two powders for which the monitoring system believes there is a potential inventory problem. The O&#39;s in columns 180 and 181 indicate no additional powder problems have been identified by the monitoring system. 
     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.