Source: http://www.google.com/patents/US5949235?dq=3798360
Timestamp: 2013-12-21 03:46:25
Document Index: 146496620

Matched Legal Cases: ['art. 2', 'art. 8', 'art. 9', 'art. 15', 'art. 17', 'art.\n20', 'art. 21', 'art.\n24', 'art 12', 'art 12', 'arts 12', 'arts 12', 'arts 12', 'art 12', 'arts 12', 'arts 12', 'art 12', 'art 12', 'art 12', 'art 12', 'art 12', 'art 12', 'art 12', 'art 12', 'arts 12', 'arts 12', 'art 12', 'arts 12', 'arts 12', 'arts 12', 'art 12']

Patent US5949235 - System and method for detection and control of ungrounded parts in a ... - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inAdvanced Patent SearchPatentsA system and method for detecting and controlling ungrounded parts during the electrostatic coating process in order to improve production flow, provide an overall cost saving by efficient use of the coating material and prevention of accidental fires and false shutdown during production. The system...http://www.google.com/patents/US5949235?utm_source=gb-gplus-sharePatent US5949235 - System and method for detection and control of ungrounded parts in a production coating lineAdvanced Patent SearchPublication numberUS5949235 APublication typeGrantApplication numberUS 08/493,639Publication dateSep 7, 1999Filing dateJun 22, 1995Priority dateJun 22, 1995Fee statusPaidAlso published asWO1997000729A1Publication number08493639, 493639, US 5949235 A, US 5949235A, US-A-5949235, US5949235 A, US5949235AInventorsDavid A. Castleman, Chris A. Selstad, Anthony B. WilliamsOriginal AssigneeFire Sentry CorporationExport CitationBiBTeX, EndNote, RefManPatent Citations (10), Referenced by (9), Classifications (16), Legal Events (3) External Links: USPTO, USPTO Assignment, EspacenetSystem and method for detection and control of ungrounded parts in a production coating lineUS 5949235 AAbstract A system and method for detecting and controlling ungrounded parts during the electrostatic coating process in order to improve production flow, provide an overall cost saving by efficient use of the coating material and prevention of accidental fires and false shutdown during production. The system of the present invention comprises a detection system for detecting any ungrounded parts prior to entering a coating environment, such as a painting booth. The detection system in accordance with one embodiment, comprises an array of detectors, specifically, an ultraviolet sensor, a radio-frequency wave sensor, an acoustic sensor and a light sensor, which upon sensing specific characteristics generate representative signal waveforms. These waveforms are than compared with stored waveforms relating to profiles of sparking or corona discharge characteristics. Correlation circuits may correlate data obtained by two or more sensors in order to ensure that the spark or corona discharge is caused by an ungrounded part. In accordance with an alternative embodiment, the detection system comprises a measuring device, such as a sensitive electric field meter, for measuring the electrical potential field between each part to be coated and ground.
What is claimed is: 1. A system for detecting and controlling ungrounded or inadequately grounded parts prior to subjecting said parts to an electrostatic coating process, comprising:a source for imparting an electrical charge to said parts under test; a detection system for sensing specific characteristics of ungrounded or inadequately grounded parts under test, such as sparking or corona discharge characteristics, and generating waveforms representative of said specific characteristic by utilizing a plurality of distinct sensing techniques; a memory coupled to said detection system for storing waveforms representative of profiles of sparking or corona discharge characteristics; and a control circuit coupled to said detection system and said memory for receiving said waveforms generated by said detection system and comparing said waveforms with said waveforms stored in said memory and providing output signals, said control circuit comprising correlation circuits to correlate output signals obtained by at least two of said two distinct sensing techniques to confirm existence of an ungrounded or poorly grounded part. 2. A system for detecting and controlling ungrounded or inadequately grounded parts according to claim 1, wherein said detection system comprises an ultraviolet sensor for sensing ultraviolet radiation within a predetermined spectral band and generating a signal representative of the sensed radiation.
3. A system for detecting and controlling ungrounded or inadequately grounded parts according to claim 1, wherein said detection system comprises a RF sensor for sensing radio-frequency magnetic waves and generating a representative sensed signal.
4. A system for detecting and controlling ungrounded parts or inadequately grounded parts according to claim 1, wherein said detection system comprises an acoustic sensor for sensing acoustic waves and for generating a representative sensed signal.
5. A system for detecting and controlling ungrounded parts or inadequately grounded parts according to claim 1, further comprising:a light source for emitting light; and a light sensor oriented relative to said light source to detect when said parts pass said light source. 6. A system for detecting and controlling ungrounded parts or inadequately grounded parts according to claim 1, further comprising:a plurality of function indicators coupled to said control circuit and selectively actuated by said control circuit to indicate a specific one of a plurality of conditions. 7. A system for detecting and controlling ungrounded or inadequately grounded parts prior to subjecting said parts to an electrostatic coating process, comprising:a source for imparting an electrical charge to said parts under test; and a detector for measuring the electrical field between a specific part under test and ground to determine if a measured value for said part under test is greater than a predetermined threshold generally indicative of an ungrounded or inadequately grounded part. 8. A process for detecting and controlling ungrounded or inadequately grounded parts prior to subjecting said parts to an electrostatic coating process, comprising the steps of:imparting an electrical charge to said parts under test; sensing specific characteristics of ungrounded or inadequately grounded parts under test, such as sparking or corona discharge characteristics; generating waveforms representative of said specific characteristic by utilizing a plurality of distinct sensing techniques; storing waveforms representative of profiles of sparking or corona discharge characteristics; receiving said waveforms generated by said detection system and comparing said waveforms with said stored waveforms to provide output signals; correlating output signals obtained by at least two distinct sensing techniques to confirm existence of an ungrounded or poorly grounded part. 9. A process for detecting and controlling ungrounded or inadequately grounded parts according to claim 8, wherein said sensing step further comprises the step of:sensing ultraviolet radiation within a predetermined spectral band and generating a signal representative of the sensed radiation. 10. A process for detecting and controlling ungrounded or inadequately grounded parts according to claim 8, wherein said sensing step further comprises the step of:sensing radio-frequency magnetic waves and generating a representative sensed signal. 11. A process for detecting and controlling ungrounded parts or inadequately grounded parts according to claim 8, wherein said sensing step further comprises the step of:sensing acoustic waves and for generating a representative sensed signal. 12. A process for detecting and controlling ungrounded parts or inadequately grounded parts according to claim 8, further comprising the steps of:emitting light from a light source located over said parts under test; and orienting a light sensor relative to said light source to detect when said parts pass said light source. 13. A process for detecting and controlling ungrounded parts or inadequately grounded parts according to claim 8, further comprising the step of:selectively actuating one of a plurality of function indicators indicative of a specific one of a plurality of conditions. 14. A process for detecting and controlling ungrounded or inadequately grounded parts prior to subjecting said parts to an electrostatic coating process, comprising the steps of:imparting an electrical charge to said parts under test; and measuring the electrical field between a specific part under test and ground to determine if a measured value for said part under test is greater than a predetermined threshold generally indicative of an ungrounded or inadequately grounded part. 15. A process for detecting and controlling ungrounded or inadequately grounded parts in a production line of parts for electrostatic coating, comprising the steps of:imparting an electrical charge to said parts in said production line prior to subjecting said parts to an electrostatic coating process; performing an initial test on each of said parts in said production line to identify ungrounded or inadequately grounded parts by sensing specific characteristics of each of said parts; and repeating said test on each part subsequent to said initial test in the event imparting said electrical charge during said initial test successfully grounded a previously ungrounded part to avoid an undesirable shutdown of said production line. 16. A system for detecting and controlling ungrounded or inadequately grounded parts in a production process, comprising:a source for imparting an electrical charge to the parts; a detector for using a plurality of distinct sensing methodologies to sense specific characteristics of ungrounded or inadequately grounded parts and for generating digital representations of waveforms representing the sensed characteristics; a memory coupled to said detector for storing digital representations of waveforms representing predetermined profiles of characteristics of ungrounded or inadequately grounded parts; and a microprocessor coupled to said detector and said memory for receiving the digital representations of waveforms generated by said detector and for digitally comparing the received digital representations of waveforms with the digital representations of waveforms stored in said memory and for providing output signals in response to the comparison, said microprocessor comprising a plurality of correlation circuits for correlating output signals representing at least two distinct sensing methodologies to correctly confirm existence of an ungrounded or inadequately grounded part. 17. The system of claim 16, wherein said detector comprises an ultraviolet radiation sensor for sensing ultraviolet radiation within a predetermined spectral band and generating a signal representing the sensed radiation, and wherein one of the at least two distinct sensing methodologies comprises ultraviolet radiation sensing.
18. The system of claim 16, further comprising a plurality of function indicators coupled to said microprocessor and selectively actuated by said microprocessor to indicate a specific one of a plurality of conditions.
19. The system of claim 16, further comprising an alarm coupled to said microprocessor for providing a warning in response to a confirmed detection of an ungrounded or inadequately grounded part.
20. In an electrostatic paint spray coating conveyor apparatus, a system for detecting and controlling ungrounded or inadequately grounded parts, comprising:a source for imparting an electrical charge to the parts; a detector for using a plurality of distinct sensing methodologies to sense specific characteristics of ungrounded or inadequately grounded parts and for generating digital representations of waveforms representing the sensed characteristics; a memory coupled to said detector for storing digital representations of waveforms representing predetermined profiles of characteristics of ungrounded or inadequately grounded parts; and a microprocessor coupled to said detector and said memory for receiving the digital representations of waveforms generated by said detector and for digitally comparing the received digital representations of waveforms with the digital representations of waveforms stored in said memory and for providing output signals in response to the comparison, said microprocessor comprising a plurality of correlation circuits for correlating output signals representing at least two distinct sensing methodologies to correctly confirm existence of an ungrounded or inadequately grounded part. 21. The system of claim 20, wherein said detector comprises an ultraviolet radiation sensor for sensing ultraviolet radiation within a predetermined spectral band and generating a signal representing the sensed radiation, and wherein one of the at least two distinct sensing methodologies comprises ultraviolet radiation sensing.
22. The system of claim 20, further comprising a plurality of function indicators coupled to said microprocessor and selectively actuated by said microprocessor to indicate a specific one of a plurality of conditions.
23. The system of claim 20, further comprising an alarm coupled to said microprocessor for providing a warning in response to a confirmed detection of an ungrounded or inadequately grounded part.
24. The system of claim 20, further comprising a light source and a light sensor oriented relative to said light source so as to detect when the parts move past said light source.
The air spray gun 26 is mounted at a predetermined distance from the facing surface of the part 12. The distance affects both the film thickness and appearance. Spray gun manufacturers generally recommend that the spray gun 26 should be mounted at a distance of about 12 inches. Many automatic spray set-ups move the spray head away from and toward the part 12, in the event its shape changes so that a constant distance is maintained.
Prior to entering the spray booth 14, the parts 12 to be coated are tested to assure that they are adequately grounded. The parts 12 are passed proximate a high voltage source 36 with a high voltage antenna 38. The high voltage source 36 may be one available from Nordson as Model number EPU-9. Electrical charge is transferred from the high voltage source, which may operate between 60,000-120,000 volts, to the parts 12 to be coated, through a resistive air gap (shown more clearly in FIGS. 3 and 4), indicated at 42. A light source 44 may be mounted on the conveyor 16 or at any other appropriate location and utilized in conjunction with a light sensor 46 (FIG. 2) within an ungrounded part detection system 47 to sense a part 12 as it travels through the high voltage field indicated in dashed lines and referenced as 48 (FIG. 2). The detection system 47 may be located at a fixed position proximate the conveyor 16 or, alternatively, the detection system 47 may be moved or scanned over the production line of parts 12. The parts 12 within the painting booth 14 are distinguished with shading lines to indicate painted surfaces.
Referring now to FIG. 2, in accordance with one embodiment of the present invention, the detection system 47 may comprise an array of detectors or sensors utilizing one or more detection techniques well known for detection of fire. The detection system 47 may comprise a UV (ultraviolet) sensor 50 for sensing ultraviolet light, a RF (radio-frequency) sensor 52 for sensing radio-frequency electromagnetic waves and an acoustic sensor 54 for sensing acoustic waves for detecting sparking and/or corona discharge.
Each of the sensors within the detection system 47 generate representative signal waveforms when they sense specific characteristics of an ungrounded part, such as sparking or corona discharge. The UV sensor 50 utilizes well known techniques for sensing ultra-violet wavelength radiation. The UV sensor 50 is responsive to UV radiation within a spectral band selected to include UV radiation typically emitted with sparking and exclude spurious radiation from arc-welding, solar energy lighting or the like, and generates a signal representative of the sensed radiation. The RF sensor 52 utilizes well-know techniques for sensing radio-frequency electromagnetic waves and generates a representative signal. The RF sensor 52 requires only a single antenna 53 as shown in FIG. 2. The acoustic sensor 54 likewise utilizes well-known techniques of sensing acoustic waves and generates a representative signal.
The output signals from the sensors 50, 52, 54 and 46, respectively, are digitally processed and fed to a control circuit 55, which may comprise a microprocessor 56. The output signals are indicated by lead lines 58, 60, 62 and 64, respectively. The microprocessor 56 may be any suitable microprocessor known to those skilled in the art. The representative signal waveforms received from the UV sensor 50, the RF sensor 52 and the acoustic sensor 54 are then compared with stored waveforms associated with profiles of sparking or corona discharge characteristics. The waveforms associated with typical profiles of sparking or corona discharge characteristics are stored in a memory 66 of the control circuit 55.
Referring now to FIGS. 2 and 4, in accordance with a preferred embodiment of the present invention, the control circuit 55 comprises correlation circuitry 68 (FIG. 2) to correlate data obtained by at least two of the sensing techniques in order to confirm that a spark or corona discharge is caused by an ungrounded part 12 under test, rather than by an external source, such as lightning. FIG. 4 illustrates an exemplary situation where sensed data from the UV sensor 50 (also indicated as D1) and the RF sensor 52 (also indicated as D2) is used to confirm that an observed spark or corona discharge results from a part 12 under test, rather than other UV or RF sources. Of course, sensed data from any combination of the three sensors 50, 52 and 54 may be used to confirm that an observed spark is from the part 12 under test.
If a spark or corona discharge is detected, the test should be repeated in the event the spark or corona discharge has burned through the insulating crust between the part 12 and the hook 22. In such cases performing the initial test or check serves to ground a part 12. Accordingly, repeating the test confirms that the particular part 12 is grounded, which prevents a premature and false indication that temporary shutdown of the production line is required.
Upon confirmation that the spark or corona discharge is caused by an ungrounded part, information data is relayed to the central control system 34 as indicated by data bus 70. Select circuits (shown as part of the central control system) within the central control system 34 associated with select functions, such as an alert 72, a fire alarm 74, a system fault indicator 76, an ungrounded part indicator 78 and the like may be selectively activated to actuate an appropriate one of the select functions. For example, when a part is found to be ungrounded, the central control system 34 may actuate the ungrounded part indicator 78 or the alert 72 or both. Likewise, when flame is detected by the flame detector 32 (FIG. 1), the central control system 34 may actuate the fire alarm 74. Upon detecting some system fault or error, the central control system may actuate the system fault indicator 76 to cause a shutdown of the production line.
Referring now to FIG. 3, in accordance with an alternative embodiment, an ungrounded part is detected by inducing a charge in a part 12 under test using direct current (DC) and measuring the electrical field around the charged part 12. In accordance with this embodiment, the high voltage source 36 (supplying between 60,000-120,000 Volts DC) is disposed proximate the conveyor 16, such that the line of parts 12 travel anywhere within 3 inches and 10 feet from the high voltage source 36. In an exemplary embodiment, the high voltage source 36 is positioned such that the line of parts 12 pass between 3 to 6 inches from the high voltage source 36. The high voltage source 36 is then turned off and the electrical potential field between the part 12 and ground is measured by using a sensitive electric field meter 80, for example an electrostatic meter Model ESM 5000, manufactured by Davis Instruments. If the parts 12 under test are properly connected to ground, the induced charge will drain off. Accordingly, the meter 80 provides no indication of an electrical field. However, if the parts 12 under test are ungrounded or inadequately grounded, the parts 12 retain a charge above a certain threshold, which when detected by the meter 80 provides an accurate indication of the status of that part 12.
FIG. 1 is a diagrammatic illustration of an electrostatic coating system and process in accordance with the present invention, in which parts are moved by a conveyor through a coating zone after a detection system checks for ungrounded parts in the production paint line;
FIG. 2 is a block diagram of one embodiment of the detection system of FIG. 1 wherein sparking or corona discharge induced by a high voltage is observed;
FIG. 3 is a diagrammatic illustration of another embodiment of the detection system wherein the dissipation of charge induced within an exemplary part is measured; and
FIG. 4 is a diagrammatic illustration of the embodiment of FIG. 2 showing the correlation technique.
FIELD OF THE INVENTION This invention relates generally to the field of electrostatic coating of parts in a production line, for example, electrostatic painting (liquid and powder). More specifically, this invention relates to the field of detecting and controlling ungrounded parts during the electrostatic coating process in order to improve production flow, provide an overall cost savings by facilitating efficient use of the coating material, and prevent accidental fires and undesirable hindrances during production, for example, false shutdown.
BACKGROUND OF THE INVENTION For many years, electrostatic coating or spraying has been a widely accepted technique for large scale application of paint, as for example in a production painting line. Typically, spraying involves the movement of very small droplets of "liquid" paint or particles of "powdered" paint from a nozzle to the surface of a part to be coated. The droplet or particle size may vary from less than 0.001 inches (0.025 mm) to greater than 0.1 inches (2.54 mm) depending on the paint viscosity and the air pressure. When the droplets fall on the surface of the part, they flow together to form a continuous wet coat.
SUMMARY OF THE INVENTION The present invention is directed to a system and method for detecting and controlling ungrounded parts during the electrostatic coating process in order to improve production flow, provide an overall cost savings by facilitating efficient use of the coating material, and prevent accidental fires and undesirable hindrances during production, for example, false shutdown.
The system of the present invention comprises a detection system for detecting any ungrounded parts prior to those parts entering the coating zone, such as a painting booth. The detection system in accordance with one embodiment, utilizes one or more detection techniques, namely, utilizing ultraviolet light, radio-frequency electromagnetic waves, acoustic waves and/or light for detecting sparking and/or corona discharge. In accordance with a preferred embodiment the detection system employs a "correlation technique" for detecting ungrounded parts, which utilizes two or more detection techniques to confirm the existence of an ungrounded part. Upon detecting an ungrounded part, the part may be removed from the production line and steps to properly ground it may be taken, for example, the hook maybe cleaned or the like. The correlation of two detection methodologies thus prevents false shutdowns in the production line.
The detection system may comprise an array of detectors, specifically an ultraviolet sensor, a radio-frequency wave sensor, an acoustic sensor and a light sensor, which generate representative signal waveforms when they sense specific characteristics of an ungrounded part. These waveforms are then compared with stored waveforms relating to profiles of sparking or corona discharge characteristics by a control circuit, such as a microprocessor. Correlation circuits may correlate data obtained by two or more sensing techniques in order to confirm that the spark of corona discharge is caused by an ungrounded part. Upon sensing an actual ungrounded part, select circuits are activated to actuate an appropriate one of several functions, such as an alert, a system fault and the like, connected in parallel.
In accordance with an alternative embodiment of the present invention, the detection system comprises a measuring device, such as a sensitive electric field meter, for measuring the electrical potential field between the part and ground.
Patent CitationsCited PatentFiling datePublication dateApplicantTitleUS28394 *May 22, 1860 Machine for printing butterUS3739228 *Feb 18, 1972Jun 12, 1973Air IndApparatus for testing electrical contact between metallic objectsUS3787707 *May 16, 1973Jan 22, 1974Ransburg Electro Coating CorpSpark detector apparatus and methodUS4718497 *Nov 25, 1986Jan 12, 1988Graviner LimitedFire and explosion detection and suppressionUS5278512 *May 15, 1992Jan 11, 1994Richard GoldsteinApparatus and method for continuously monitoring grounding conductor resistance in power distribution systemsUS5311167 *Aug 14, 1991May 10, 1994Armtec Industries Inc.UV/IR fire detector with dual wavelength sensing IR channelUS5339070 *Jul 21, 1992Aug 16, 1994Srs TechnologiesCombined UV/IR flame detection systemUS5598099 *Jun 22, 1995Jan 28, 1997Fire Sentry Systems, Inc.System and method for coincidence detection of ungrounded parts with detectors located within and outside a production coating areaUS5626236 *Jan 11, 1993May 6, 1997Autoline, Inc.Method and apparatus for handling objectsUS5644223 *May 12, 1995Jul 1, 1997International Business Machines CorporationUniform density charge deposit source* Cited by examinerReferenced byCiting PatentFiling datePublication dateApplicantTitleUS6104297 *Jan 20, 1999Aug 15, 2000Danilychev; Vladimir A.Corona discharge detection systemUS6420874 *Jul 26, 2000Jul 16, 2002Ford Global Tech., Inc.Electrostatic painting system and methodUS6476396 *Apr 7, 2000Nov 5, 2002Keith W. ForsythElectro-optical, non-contact measurement of electrical dischargesUS6726772Mar 7, 2002Apr 27, 2004Illinois Tool Works Inc.Method and apparatus for securing articles to be coated to a conveyorUS8527817 *Nov 19, 2010Sep 3, 2013International Business Machines CorporationDetecting system component failures in a computing systemUS8547238 *Jun 30, 2010Oct 1, 2013Knowflame, Inc.Optically redundant fire detector for false alarm rejectionUS20120001760 *Jun 30, 2010Jan 5, 2012Polaris Sensor Technologies, Inc.Optically Redundant Fire Detector for False Alarm RejectionUS20120131390 *Nov 19, 2010May 24, 2012International Business Machines CorporationDetecting System Component Failures In A Computing SystemWO2012042340A1 *Sep 27, 2011Apr 5, 2012Toyota Jidosha Kabushiki KaishaElectrostatic coating apparatus and grounding condition inspection method* Cited by examinerClassifications U.S. Classification324/509, 361/228, 239/708, 324/456International ClassificationB05B5/08, H02H7/00, G01R31/02, B05B12/12Cooperative ClassificationH02H7/003, G01R31/026, B05B12/12, B05B5/08European ClassificationH02H7/00D, B05B12/12, B05B5/08, G01R31/02C4Legal EventsDateCodeEventDescriptionFeb 9, 2011FPAYFee paymentYear of fee payment: 12Feb 20, 2007FPAYFee paymentYear of fee payment: 8Dec 30, 2002FPAYFee paymentYear of fee payment: 4RotateOriginal ImageGoogle Home - Sitemap - USPTO Bulk Downloads - Privacy Policy - Terms of Service - About Google Patents - Send FeedbackData provided by IFI CLAIMS Patent Services©2012 Google