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WO2012028942A2 - Electrostatic coating apparatus - Google Patents

Electrostatic coating apparatus Download PDF

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Publication number
WO2012028942A2
WO2012028942A2 PCT/IB2011/002013 IB2011002013W WO2012028942A2 WO 2012028942 A2 WO2012028942 A2 WO 2012028942A2 IB 2011002013 W IB2011002013 W IB 2011002013W WO 2012028942 A2 WO2012028942 A2 WO 2012028942A2
Authority
WO
WIPO (PCT)
Prior art keywords
high voltage
voltage
resistance
robot arm
input terminal
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/IB2011/002013
Other languages
French (fr)
Other versions
WO2012028942A3 (en
Inventor
Isamu Yamasaki
Fumihiro Takase
Kimiyoshi Nagai
Atsushi Kawamoto
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Toyota Motor Corp
Original Assignee
Toyota Motor Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Toyota Motor Corp filed Critical Toyota Motor Corp
Publication of WO2012028942A2 publication Critical patent/WO2012028942A2/en
Publication of WO2012028942A3 publication Critical patent/WO2012028942A3/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B5/00—Electrostatic spraying apparatus; Spraying apparatus with means for charging the spray electrically; Apparatus for spraying liquids or other fluent materials by other electric means
    • B05B5/025—Discharge apparatus, e.g. electrostatic spray guns
    • B05B5/053—Arrangements for supplying power, e.g. charging power
    • B05B5/0531—Power generators
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B5/00—Electrostatic spraying apparatus; Spraying apparatus with means for charging the spray electrically; Apparatus for spraying liquids or other fluent materials by other electric means
    • B05B5/025—Discharge apparatus, e.g. electrostatic spray guns
    • B05B5/053—Arrangements for supplying power, e.g. charging power
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of AC power input into DC power output; Conversion of DC power input into AC power output
    • H02M7/02—Conversion of AC power input into DC power output without possibility of reversal
    • H02M7/04—Conversion of AC power input into DC power output without possibility of reversal by static converters
    • H02M7/06—Conversion of AC power input into DC power output without possibility of reversal by static converters using discharge tubes without control electrode or semiconductor devices without control electrode
    • H02M7/10—Conversion of AC power input into DC power output without possibility of reversal by static converters using discharge tubes without control electrode or semiconductor devices without control electrode arranged for operation in series, e.g. for multiplication of voltage
    • H02M7/103—Containing passive elements (capacitively coupled) which are ordered in cascade on one source
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B13/00—Machines or plants for applying liquids or other fluent materials to surfaces of objects or other work by spraying, not covered by groups B05B1/00 - B05B11/00
    • B05B13/02—Means for supporting work; Arrangement or mounting of spray heads; Adaptation or arrangement of means for feeding work
    • B05B13/04—Means for supporting work; Arrangement or mounting of spray heads; Adaptation or arrangement of means for feeding work the spray heads being moved during spraying operation
    • B05B13/0447—Installation or apparatus for applying liquid or other fluent material to conveyed separate articles
    • B05B13/0452—Installation or apparatus for applying liquid or other fluent material to conveyed separate articles the objects being vehicle components, e.g. vehicle bodies
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B5/00—Electrostatic spraying apparatus; Spraying apparatus with means for charging the spray electrically; Apparatus for spraying liquids or other fluent materials by other electric means
    • B05B5/025—Discharge apparatus, e.g. electrostatic spray guns
    • B05B5/053—Arrangements for supplying power, e.g. charging power
    • B05B5/0533—Electrodes specially adapted therefor; Arrangements of electrodes

Definitions

  • the invention relates to a technique used in an electrostatic coating apparatus that performs electrostatic coating while applying a high voltage to a coating gun and a robot arm.
  • An optimum applied voltage for repulsing the coating mist differs from the voltage applied to the coating gun, and therefore different voltages are preferably applied to the robot arm and the coating gun.
  • a high voltage generation device for applying an electrostatic high voltage to the coating gun is provided separately to a high voltage generation device for applying an electrostatic high voltage to the robot arm, leading to an increase in the complexity of the electrostatic coating apparatus and an increase in cost.
  • the invention provides an electrostatic coating apparatus capable of applying different electrostatic high voltages to a coating gun and a robot arm using a simply configured high voltage generation device.
  • a first aspect of the invention relates to an electrostatic coating apparatus including: a coating gun that sprays a coating; a robot arm that supports the coating gun displaceably; and a high voltage generation device that generates high voltages to be applied to the coating gun and the robot arm.
  • the high voltage generation device includes: a voltage boosting portion that boosts a voltage and that includes a first output portion and a second output portion for outputting the high voltages; and a resistance portion that has an input terminal, into which the high voltages are inputted, a ground terminal grounded to an earth, an electric resistance body that connects the input terminal and the ground terminal, and a contact portion that forms a contact in an intermediate position of the resistance body between the input terminal and the ground terminal.
  • the first output portion is connected to the coating gun
  • the second output portion is connected to the input terminal of the resistance portion
  • the contact portion of the resistance portion is connected to the robot arm.
  • the resistance body may double as a bleeder resistor provided on an earth path of the voltage boosting portion to reduce a leak current.
  • the high voltage generation device can be configured even more compactly.
  • the resistance body may be constituted by a plurality of resistors connected in series, and the contact portion may be connected to any one of respective connection terminals connecting the respective resistors.
  • a value of the high voltage applied to the robot arm can be modified using a simple configuration.
  • the resistance body may be constituted by a variable resistor in which a resistance value between the input terminal and the contact portion is variably set.
  • the value of the high voltage applied to the robot arm can be modified more finely using a simple configuration.
  • FIG 1 is a schematic diagram showing an overall configuration of an electrostatic coating apparatus according to an embodiment of the invention.
  • FIG. 2 is a schematic diagram showing how soiling with a coating is prevented in the electrostatic coating apparatus according to an embodiment of the invention
  • FIG. 3 is 'a schematic diagram showing a high voltage generation device according to a first embodiment, provided in the electrostatic coating apparatus according to an embodiment of the invention
  • FIG. 4 is a schematic diagram showing a case in which a resistance portion according to the first embodiment is connected to a voltage boosting portion according to the first embodiment;
  • FIG. 5 is a schematic diagram showing a case in which a resistance portion according to a second embodiment is connected to the voltage boosting portion according to the first embodiment;
  • FIG. 6 is a schematic diagram showing a high voltage generation device according to the second embodiment, provided in the electrostatic coating apparatus according to an embodiment of the invention.
  • FIG 7 is a schematic diagram showing a voltage boosting portion according to the second embodiment.
  • FIG 8 is a schematic diagram showing a voltage boosting portion according to a third embodiment.
  • FIGS. 1 and 2 An embodiment of the invention will be described. First, an overall configuration of an electrostatic coating apparatus according to an embodiment of the invention will be described using FIGS. 1 and 2.
  • an electrostatic coating apparatus 1 is an apparatus for performing electrostatic coating on a coating subject (a vehicle body 2) to be subjected to coating, and includes a coating gun 3, a robot arm 4, a high voltage generation device 9, and so on. Note that in the example described in this embodiment, the electrostatic coating apparatus 1 is used in an application for coating the vehicle body 2 of an automobile, but the electrostatic coating apparatus according to the invention is not limited to this application.
  • the coating gun 3 is a device for spraying a coating onto the coating subject vehicle body 2, and includes a bell cap 3a, a ring electrode 3b, and so on.
  • the coating gun 3 is a rotary atomization type coating device capable of rotating the bell cap 3a using driving means such as an air motor, not shown in the drawing, so that a fluid coating spread onto an inner surface of the bell cap 3a is atomized by centrifugal force.
  • the robot arm 4 is constituted by a vertical arm 5 coupled rotatably to a base portion 7 by a lower portion thereof, and a horizontal arm 6 coupled rotatably to an upper portion of the vertical arm 5 by a rear end portion thereof.
  • the coating gun 3, which is provided on a tip end portion of the horizontal arm 6, can be displaced relative to the vehicle body 2 by rotating the vertical arm 5 and the horizontal arm 6 about respective rotary fulcrums thereof.
  • the horizontal arm 6 includes a first arm portion 6a, a second arm portion 6b, and a third arm portion 6c, wherein a coupling pipe 3e of the coating gun 3 is coupled to a tip end portion of the first arm portion 6a, the first arm portion 6a is coupled to a tip end portion of the second arm portion 6b, the second arm portion 6b is coupled to a tip end portion of the third arm portion 6c, and the vertical arm 5 is coupled rotatably to a base end portion of the third arm portion 6c.
  • an angle of the coating gun 3 can be modified in a clockwise direction or a counterclockwise direction in FIGS. 1 and 2.
  • the coating gun 3 is attached to a tip end of the coupling pipe 3e, and the coupling pipe 3e is driven to rotate in an axial direction relative to the first arm portion 6a.
  • the angle of the coating gun 3 can be modified about an axis of the coupling pipe 3e.
  • the angle of the coating gun 3 relative to the vehicle body 2 can be set freely.
  • the high voltage generation device 9 is connected to the coating gun 3 and the robot arm 4.
  • the high voltage generation device 9 generates high voltages that are applied to the coating gun 3 and the robot arm 4.
  • the high voltage generation device 9 includes a voltage generation portion 21 serving as a site for generating a voltage and controlling the voltage, and a voltage boosting portion 22 serving as a site for boosting the voltage generated in the voltage generation portion 21.
  • the voltage boosting portion 22 of the high voltage generation device 9 is disposed in an interior of the second arm portion 6b, and the voltage generation portion 21 is disposed on an exterior of the robot arm 4.
  • a low voltage cable 23 is laid through the respective portions 6b, 6c of the robot arm 4 and the vertical arm 5 and led to the exterior from a midway point in the vertical arm 5.
  • the voltage generation portion 21 and the voltage boosting portion 22 are connected by the low voltage cable 23.
  • high voltage cables 10, 11 are laid through the respective portions 6a, 6b of the robot arm 4 and the interior of the coating gun 3 such that the voltage boosting portion 22 is connected respectively to the coating gun 3 and the robot arm 4 by the high voltage cables 10, 11.
  • high voltages are applied to the coating gun 3 and the robot arm 4.
  • the high voltage generation device 9 is connected to the first arm portion 6a of the robot arm 4 such that a high voltage having an identical negative polarity to the voltage applied to the coating gun 3 is applied to the first arm portion 6a.
  • a high voltage generation device 9 By causing the high voltage generation device 9 to apply an electrostatic high voltage to the first arm portion 6a, an electrostatic high voltage is also applied to a ring electrode 8 that is conductive with the first arm portion 6a.
  • an electrostatic field is formed in a radial shape from tip end portions of a plurality of needle-shaped electrodes 8a formed on the ring electrode 8.
  • the coating mist is electrostatically repulsed by this electrostatic field, and therefore the coating mist is prevented from adhering to the first arm portion 6a.
  • a difference occurs between the coating gun 3 and the first arm portion 6a in a charge of the coating mist floating on the periphery of the respective components. More specifically, a coating mist maintaining a high charge immediately after being sprayed from the coating gun 3 exists in a comparatively large amount on the periphery of the coating gun 3, whereas a coating mist that approaches the coating subject and so on after being sprayed from the coating gun 3 such that the charge thereof is emitted exists in a comparatively large amount on the periphery of the first arm portion 6a. Therefore, a potential for realizing effective electrostatic repulsion differs between the coating gun 3 and the first arm portion 6a. Accordingly, the high voltage applied to the first arm portion 6a preferably has a lower voltage than the high voltage applied to the coating gun 3.
  • high voltages having different voltages are applied respectively to the coating gun 3 and the first arm portion 6a by connecting separate high voltage generation devices to the coating gun 3 and the first arm portion 6a.
  • a high voltage generation device having a voltage generation portion and a voltage boosting portion is provided for the coating gun 3
  • a high voltage generation device having a voltage generation portion and a voltage boosting portion is provided for the first arm portion 6a.
  • high voltages having two different voltages can be output by the high voltage generation device 9 including only one voltage generation portion and one voltage boosting portion.
  • a high voltage generation device 9X serving as the high voltage generation device 9 according to the first embodiment includes the voltage generation portion 21, the voltage boosting portion 22, the low voltage cable 23, and so on.
  • the voltage generation portion 21 is a site for generating voltages serving as the basis of the high voltages applied to the coating gun 3 and the robot arm 4, and includes a power supply portion 27, an amplifier 28, a central processing unit (CPU) 29, a random access memory (RAM) 30, a relay 31, a push-pull oscillation device 32, a voltage sensor 33, a current sensor 34, band pass filters 35, 36, and so on.
  • a power supply portion 27 an amplifier 28, a central processing unit (CPU) 29, a random access memory (RAM) 30, a relay 31, a push-pull oscillation device 32, a voltage sensor 33, a current sensor 34, band pass filters 35, 36, and so on.
  • CPU central processing unit
  • RAM random access memory
  • the voltage boosting portion 22 is a site for boosting the voltage generated by the voltage generation portion 21, and includes a high voltage transformer 24, a Cockcroft-Walton circuit (CW circuit) 25 serving as a rectifier and a multiplier for generating a high voltage and constituted by a combination of a plurality of capacitors, diodes, and the like, and so on. Further, as shown in FIG 4, the high voltage transformer 24 includes a primary winding 24a and a secondary winding 24b, and the CW circuit 25 is connected to the secondary winding 24b side.
  • CW circuit Cockcroft-Walton circuit
  • the voltage generation portion 21 includes an output terminal 21a for outputting an operating voltage to a center phase (a CT phase) of the primary winding 24a, an output terminal 21b for outputting a drive signal to a drive A phase (a DA phase) of the primary winding 24a, and an output terminal 21c for outputting a drive signal to a drive B phase (a DB phase) of the primary winding 24a.
  • the voltage generation portion 21 includes an input terminal 21d for inputting a current feedback signal (an IM signal) indicating an overall generated current value of the CW circuit 25 to the CPU 29, an input terminal 21e for inputting a voltage feedback signal (a VM signal) indicating a high voltage value following boosting by the CW circuit 25 to the CPU, a ground terminal 21f for grounding the voltage generation portion 21, and so on.
  • a current feedback signal an IM signal
  • a VM signal voltage feedback signal
  • the voltage boosting portion 22 includes an input terminal 22a connected to the CT phase of the primary winding 24a of the high voltage transformer 24, an input terminal 22b connected to the DA phase of the primary winding 24a, and an input terminal 22c connected to the DB phase of the primary winding 24a. Further, the voltage boosting portion 22 includes an output terminal 22d for outputting the IM signal indicating the overall generated current value of the CW circuit 25, an output terminal 22e for outputting the VM signal indicating the high voltage value following boosting by the CW circuit 25, a ground terminal 22f for grounding the CW circuit 25, and so on.
  • a voltage boosting portion 22X may be employed as the voltage boosting portion 22.
  • the CW circuit 25 is connected to the ground terminal 22f such that a charge charged to the coating gun 3 and so on is released to the earth.
  • a bleeder resistor 26 for suppressing a leak current is provided on a grounding line connecting the CW circuit 25 to the ground terminal 22f.
  • high voltage output terminals 22g, 22h of two systems are provided as terminals for outputting high voltages generated by the CW circuit 25.
  • the low voltage cable 23 is a bundle of various cables for electrically connecting the voltage generation portion 21 to the voltage boosting portion 22X, and is constituted by a CT input line 23a, a DA input line 23b, a DB input line 23c, an IM signal line 23d, a VM signal line 23e, a common line 23f, and so on.
  • the CT input line 23a is a cable for inputting the operating voltage generated by the voltage generation portion 21 into the CT phase of the primary winding 24a, and is connected between the output terminal 21a of the voltage generation portion 21 and the input terminal 22a of the voltage boosting portion 22X.
  • the DA input line 23b is a cable for inputting the drive signal generated by the voltage generation portion 21 into the DA phase of the primary winding 24a, and is connected between the output terminal 21b of the voltage generation portion 21 and the input terminal 22b of the voltage boosting portion 22X.
  • the DB input line 23c is a cable for inputting the drive signal generated by the voltage generation portion 21 into the DB phase of the primary winding 24a, and is connected between the output terminal 21c of the voltage generation portion 21 and the input terminal 22c of the voltage boosting portion 22X.
  • the IM signal line 23d is a cable for inputting the IM signal generated by the voltage boosting portion 22X into the CPU 29, and is connected between the input terminal 21d of the voltage generation portion 21 and the output terminal 22d of the voltage boosting portion 22X.
  • the VM signal line 23e is a cable for inputting the VM signal generated by the voltage boosting portion 22X into the CPU 29, and is connected between the input terminal 21 e of the voltage generation portion 21 and the output terminal 22e of the voltage boosting portion 22X.
  • the common line 23f is a cable for grounding the voltage generation portion 21 and the voltage boosting portion 22X to the earth and setting a common reference potential of 0 V, and is connected between the ground terminal 21f of the voltage generation portion 21 and the ground terminal 22f of the voltage boosting portion 22X.
  • the voltage generation portion 21 generates the operating voltage by having the amplifier 28 regulate an output voltage generated by the power supply portion 27 in accordance with a command value from the CPU 29.
  • the operating voltage generated in this case is measured by the voltage sensor 33 and the current sensor 34 provided on an operating voltage supply line. The measured value is fed back to the CPU 29, whereupon the CPU 29 regulates the operating voltage to match the command value.
  • the IM signal and the VM signal are fed back to the CPU 29, and the CPU 29 determines the command value to be issued from the CPU 29 to the amplifier 28 through calculation on the basis of the respective feedback signals, conditions stored in the RAM 30, and so on.
  • the IM signal, VM signal, and so on are input into the CPU 29 via the band pass filters 35, 36, and so on.
  • the voltage generation portion 21 generates the drive signals to be input into the respective drive phases of the primary winding 24a in accordance with a command value from the CPU 29 using the push-pull oscillation device 32. Further, the IM signal and the VM signal are fed back to the CPU 29, and the CPU 29 determines the command value to be issued from the CPU 29 to the push-pull oscillation device 32 through calculation on the basis of the respective feedback signals, the conditions stored in the RAM 30, and so on.
  • a predetermined alternating current voltage can be supplied to the primary winding 24a of the high voltage transformer 24.
  • the CW circuit 25 connected to the secondary winding 24b can then boost the operating voltage supplied to the primary winding 24a to a predetermined magnification corresponding to a number of connection stages of the capacitors and diodes, and as a result, a direct current high voltage having a predetermined voltage value can be generated between points A and B of the CW circuit 25 in FIG 4.
  • one high voltage output terminal 22g of the output terminals 22g, 22h of the two systems connected to an output point B is a terminal for outputting the high voltage to be applied to the coating gun 3.
  • the high voltage output terminal 22g and the coating gun 3 are connected by the high voltage cable 10.
  • the other high voltage output terminal 22h is a terminal for outputting the high voltage to be applied to the robot arm 4 (more specifically, the first arm portion 6a).
  • a resistance portion 37 is connected to the high voltage output terminal 22h by a high voltage cable 12 such that the high voltage is applied to the first arm portion 6a via the resistance portion 37.
  • a resistance portion 37X according to the first embodiment may be employed in the high voltage generation device 9X as the resistance portion 37.
  • the resistance portion 37 is a site that serves to regulate the high voltage boosted by the voltage boosting portion 22 to a suitable voltage for application to the robot arm 4, and includes a resistance body 38.
  • a resistance body 38X according to the first embodiment which is constituted by a plurality of resistors 38a (five in this embodiment) connected in series by a plurality of connection terminals 40 to 45 (six in this embodiment), is provided as the resistance body 38.
  • connection terminal 40 disposed at one end portion of the plurality of resistors 38a connected in series is connected to an input terminal 37a of the resistance portion 37X, while the connection terminal 45 disposed at the other end portion is connected to a ground terminal 37c of the resistance portion 37X.
  • the input terminal 37a is connected to the high voltage output terminal 22h of the voltage boosting portion 22X by the high voltage cable 12, and the ground terminal 37c is connected to the earth.
  • a contact portion 39 is connected to one of the connection terminals 40 to 44 forming the resistance body 38X.
  • the contact portion 39 is connected to an output terminal 37b of the resistance portion 37X.
  • the output terminal 37b of the resistance portion 37X and the robot arm 4 are connected by the high voltage cable 11.
  • An applied voltage suitable for application to the robot arm 4 is extracted from the contact portion 39 connected to one of the connection terminals 40 to 44, whereupon a high voltage is output from the output terminal 37b and applied to the robot arm 4.
  • each identical resistor i.e. resistors having identical resistance values
  • a value of a voltage at the output point B in other words, a voltage output from the high voltage output terminal 22h
  • an output voltage in a case where the contact portion 39 is connected to the connection terminal 41 shown in FIG 4 takes a voltage value of 80% of the voltage at the output point B.
  • output voltages in cases where the contact portion 39 is connected similarly to the other connection terminals 42, 43, 44 take voltage values of 60%, 40%, and 20% of the voltage at the output point B, respectively.
  • the output voltage takes an identical voltage value (i.e. 100%) to the voltage at the output point B.
  • the resistance body 38X is constituted by the plurality of resistors 38a connected in series, and the output terminal 37b is connected to one of the connection terminals 40 to 44 connecting the respective resistors 38a.
  • the resistance body 38X is formed by connecting the five identical resistors 38a (i.e. resistors having identical resistance values) in series.
  • the configuration of the resistance body 38X is not limited by the number of resistors.
  • the resistance body 38X may be formed from a plurality of resistors having different resistance values so that the value of the output high voltage can be regulated to an even more suitable voltage for application to the robot arm 4.
  • the resistance portion 37 is connected to the high voltage output terminal 22h corresponding to the robot arm 4.
  • high voltages of three or more systems may be output from the voltage boosting portion 22 and the resistance portion 37 may be connected to each additional high voltage output system.
  • a second embodiment of the high voltage generation device 9X according to the first embodiment, in which the configuration of the resistance portion 37 is modified, will now be described using FIG 5.
  • a resistance portion 37Y according to the second embodiment is employed as the resistance portion 37 connected to the voltage boosting portion 22X.
  • the resistance portion 37Y differs from the resistance portion 37X according to the first embodiment, described above, in that a resistance body 38Y according to the second embodiment is used as the resistance body 38. Note that all other configurations of the resistance portion 37Y are identical to their counterparts in the resistance portion 37X according to the first embodiment.
  • the resistance portion 37 is a site that serves to regulate the high voltage boosted by the voltage boosting portion 22 to a suitable voltage for application to the robot arm 4.
  • a single variable resistor 38b is used as the resistance body 38.
  • the variable resistor 38b includes an input terminal 46 and a ground terminal 47.
  • a movable contact portion 48 a contact position of which can be modified as desired, is provided at a midway point on an internal resistance 38c connecting the input terminal 46 and the ground terminal 47.
  • a resistance value between the input terminal 46 and the movable contact portion 48 can be modified as desired by modifying the position of the movable contact portion 48 relative to the internal resistance 38c.
  • the input terminal 46 of the variable resistor 38b is connected to the input terminal 37a of the resistance portion 37Y. Further, the ground terminal 47 is connected to the ground terminal 37c of the resistance portion 37Y. The input terminal 37a is connected to the high voltage output terminal 22h of the voltage boosting portion 22X, and the ground terminal 37c is connected to the earth. Furthermore, in the variable contact portion 48, the output terminal 37b of the resistance portion 37Y connected to the output terminal 37b of the resistance portion 37Y is connected to the robot arm 4 by the high voltage cable 11.
  • An applied voltage is regulated to a desired voltage by the variable resistor 38b, whereupon a high voltage suitable for application to the robot arm 4 is output from the output terminal 37b and applied to the robot arm 4.
  • the resistance body 38Y can be formed from the variable resistor 38b in which the resistance value between the input terminal 37a and the output terminal 37b is variably set.
  • the high voltage generation device 9X includes the bleeder resistor 26 (see FIGS. 3 to 5).
  • the bleeder resistor 26 is an electric resistance body provided on a grounding line for removing the charges charged to the coating gun 3 and the robot arm 4 in order to suppress a leak current when high voltage application by the high voltage generation device 9X is stopped.
  • a resistor having a considerably larger resistance value than a resistor 22k provided between the output point B and the coating gun 3 is used as the bleeder resistor 26.
  • the resistor 22k has a resistance value of approximately 40 ⁇
  • the bleeder resistor 26 has a resistance value of approximately 2 GQ.
  • one end portion of the resistance body 38 is connected to the input terminal 37a and the other end portion of the resistance body 38 is connected to the ground terminal 37c connected to the earth so that the high voltage input from the input terminal 37a can be regulated to a desired voltage value and output from the output terminal 37b.
  • the resistance body 38 provided in the resistance portion 37 may serve as the bleeder resistor 26.
  • the resistance portion 37 (more specifically, the resistance body 38) doubles as a bleeder resistor. Accordingly, the resistance portion 37 is built into the voltage boosting portion 22 rather than being provided separately to the voltage boosting portion 22, and disposed on the grounding line on which the bleeder resistor is conventionally disposed in place of the bleeder resistor.
  • a voltage boosting portion 22Y according to the second embodiment in which the resistance portion 37 is inbuilt on the grounding line on which the bleeder resistor is conventionally disposed, is employed as the voltage boosting portion 22.
  • the input terminal 37a of the resistance portion 37X is connected to the high voltage output terminal 22h and the ground terminal 37c is connected to the earth via the ground terminal 22f. Further, in the voltage boosting portion 22Y, the contact portion 39 connected to one of the respective connection terminals 40 to 44 constituting the resistance body 38X is connected to the output terminal 37b of the resistance portion 37X. The output terminal 37b of the resistance portion 37X and the robot arm 4 are connected by the high voltage cable 11.
  • an applied voltage suitable for application to the robot arm 4 is extracted from the contact portion 39 connected to one of the connection terminals 40 to 44, whereupon a high voltage is output from the output terminal 37b and applied to the robot arm 4.
  • the high voltage generation device 9Y employing the voltage boosting portion 22Y can be formed more compactly than the high voltage generation device 9X since the resistance portion 37 does not have to be provided separately. Further, the bleeder resistor can be omitted, and therefore the high voltage generation device 9 can be formed from a smaller number of components.
  • FIG 8 Another embodiment relating to the high voltage generation device 9Y according to the second embodiment, in which the configuration of the voltage boosting portion 22 is modified, will now be described using FIG 8.
  • a voltage boosting portion 22Z according to a third embodiment is employed as the voltage boosting portion 22.
  • the voltage boosting portion 22Z uses the resistance portion 37Y according to the second embodiment, described above, as the resistance portion 37 built into the voltage boosting portion 22.
  • the input terminal 37a of the resistance portion 37Y including the variable resistor 38b is connected to the high voltage output terminal 22h, and the ground terminal 37c is connected to the earth via the ground terminal 22f.
  • the movable contact portion 48 is connected to the output terminal 37b of the resistance portion 37Y.
  • the output terminal 37b of the resistance portion 37Y and the robot arm 4 are connected by the high voltage cable 11.
  • an applied voltage is regulated to a desired voltage by the variable resistor 38b, whereupon a high voltage suitable for application to the robot arm 4 is output from the output terminal 37b and applied to the robot arm 4.
  • the respective resistance bodies 38X, 38Y double as bleeder resistors (the conventional bleeder resistor 26) provided on an earth path of the voltage boosting portions 22Y, 22Z in order to reduce a leak current.
  • the high voltage generation device 9 can be formed more compactly.
  • the electrostatic coating apparatus 1 includes: the coating gun 3 that sprays the coating; the robot arm 4 that supports the coating gun 3 displaceably; and the high voltage generation device 9 (the high voltage generation device 9X or the high voltage generation device 9Y) that generates high voltages to be applied to the coating gun 3 and the robot arm 4, wherein the high voltage generation device 9 includes: the voltage boosting portion 22 (the respective voltage boosting portions 22X, 22Y, 22Z) for boosting a voltage, which includes the high voltage output terminals 22g, 22h serving respectively as first and second output portions for outputting the high voltages; and the resistance portion 37 (the resistance portion 37X or the resistance portion 37Y) that includes the input terminal 37a into which the high voltages are input, the ground terminal 37c grounded to the earth, the electric resistance body 38 (the resistance body 38X or the resistance body 38Y) that connects the input terminal 37a and the ground terminal 37c, and the contact portion 39 or the movable contact portion 48 that forms a contact in an intermediate position
  • the electrostatic coating apparatus 1 With the electrostatic coating apparatus 1 according to an embodiment of the invention, two sites to be subjected to soiling prevention measures, namely the coating gun 3 and the robot arm 4, can be dealt with by the single voltage boosting portion 22. Therefore, leeway can be generated in a space for housing the voltage boosting portion 22 and the low voltage cable 23 in the robot arm 4, and a number of internal wires can be reduced. As a result, a wire laying operation can be simplified, and maintenance and management can be realized easily. Further, with the electrostatic coating apparatus 1 according to an embodiment of the invention, the robot arm 4 can be made slimmer, and therefore a more compact apparatus configuration can be realized. As a result, a manufacturing cost of the electrostatic coating apparatus can be reduced and so on.

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  • Electrostatic Spraying Apparatus (AREA)
  • Spray Control Apparatus (AREA)

Abstract

A high voltage generation device (9) includes: a voltage boosting portion (22) that boosts a voltage and that includes high voltage output terminals (22g, 22h); and a resistance portion (37) that includes an input terminal (37a), a ground terminal (37c), a resistance body (38) that connects the input terminal (37a) and the ground terminal (37c), and a contact portion (39) or a variable contact portion (48) that forms a contact in an intermediate position of the resistance body (38) between the input terminal (37a) and the ground terminal (37c). The high voltage output terminal (22g) is connected to a coating gun (3), the high voltage output terminal (22h) is connected to the input terminal (37a) of the resistance portion (37), and an output terminal (37b) of the resistance portion (37) or the variable contact portion (48) is connected to a robot arm (4).

Description

ELECTROSTATIC COATING APPARATUS
BACKGROUND OF THE INVENTION 1. Field of the Invention
[0001] The invention relates to a technique used in an electrostatic coating apparatus that performs electrostatic coating while applying a high voltage to a coating gun and a robot arm. 2. Description of Related Art
[0002] In a conventional technique used in an electrostatic coating apparatus that performs electrostatic coating by applying an electrostatic high voltage to a coating gun for spraying a coating so that the coating is charged, an electrostatic high voltage having an identical polarity to the electrostatic high voltage applied to the coating gun is applied to a robot arm that supports the coating gun displaceably, and as a result, the robot arm is prevented from becoming soiled. This technique is disclosed in Japanese Patent Application Publication No. 2007-69136 (JP-A-2007-69136), described below, for example.
[0003] When the electrostatic high voltage is applied to the robot arm, an electric field is formed on the periphery of the robot arm so that a coating mist floating on the periphery of the robot arm is repulsed, and as a result, the coating is prevented from adhering to the robot arm.
[0004] An optimum applied voltage for repulsing the coating mist differs from the voltage applied to the coating gun, and therefore different voltages are preferably applied to the robot arm and the coating gun. Hence, in a conventional configuration, a high voltage generation device for applying an electrostatic high voltage to the coating gun is provided separately to a high voltage generation device for applying an electrostatic high voltage to the robot arm, leading to an increase in the complexity of the electrostatic coating apparatus and an increase in cost.
SUMMARY OF THE INVENTION
[0005] The invention provides an electrostatic coating apparatus capable of applying different electrostatic high voltages to a coating gun and a robot arm using a simply configured high voltage generation device.
[0006] A first aspect of the invention relates to an electrostatic coating apparatus including: a coating gun that sprays a coating; a robot arm that supports the coating gun displaceably; and a high voltage generation device that generates high voltages to be applied to the coating gun and the robot arm. The high voltage generation device includes: a voltage boosting portion that boosts a voltage and that includes a first output portion and a second output portion for outputting the high voltages; and a resistance portion that has an input terminal, into which the high voltages are inputted, a ground terminal grounded to an earth, an electric resistance body that connects the input terminal and the ground terminal, and a contact portion that forms a contact in an intermediate position of the resistance body between the input terminal and the ground terminal. The first output portion is connected to the coating gun, the second output portion is connected to the input terminal of the resistance portion, and the contact portion of the resistance portion is connected to the robot arm.
[0007] With the aspect described above, desired high voltages can be applied respectively to the coating gun and the robot arm by the simply configured high voltage generation device having only one voltage boosting portion. As a result, an inexpensive, compact electrostatic coating apparatus can be provided.
[0008] In the aspect described above, the resistance body may double as a bleeder resistor provided on an earth path of the voltage boosting portion to reduce a leak current.
[0009] With the aspect described above, the high voltage generation device can be configured even more compactly.
[0010] In the aspect described above, the resistance body may be constituted by a plurality of resistors connected in series, and the contact portion may be connected to any one of respective connection terminals connecting the respective resistors.
[0011] With the aspect described above, a value of the high voltage applied to the robot arm can be modified using a simple configuration.
[0012] In the aspect described above, the resistance body may be constituted by a variable resistor in which a resistance value between the input terminal and the contact portion is variably set.
[0013] With the aspect described above, the value of the high voltage applied to the robot arm can be modified more finely using a simple configuration.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Features, advantages, and technical and industrial significance of exemplary embodiments of the invention will be described below with reference to the accompanying drawings, in which like numerals denote like elements, and wherein:
FIG 1 is a schematic diagram showing an overall configuration of an electrostatic coating apparatus according to an embodiment of the invention;
FIG. 2 is a schematic diagram showing how soiling with a coating is prevented in the electrostatic coating apparatus according to an embodiment of the invention;
FIG. 3 is 'a schematic diagram showing a high voltage generation device according to a first embodiment, provided in the electrostatic coating apparatus according to an embodiment of the invention;
FIG. 4 is a schematic diagram showing a case in which a resistance portion according to the first embodiment is connected to a voltage boosting portion according to the first embodiment;
FIG. 5 is a schematic diagram showing a case in which a resistance portion according to a second embodiment is connected to the voltage boosting portion according to the first embodiment;
FIG. 6 is a schematic diagram showing a high voltage generation device according to the second embodiment, provided in the electrostatic coating apparatus according to an embodiment of the invention;
FIG 7 is a schematic diagram showing a voltage boosting portion according to the second embodiment; and
FIG 8 is a schematic diagram showing a voltage boosting portion according to a third embodiment.
DETAILED DESCRIPTION OF EMBODIMENTS
[0015] Next, an embodiment of the invention will be described. First, an overall configuration of an electrostatic coating apparatus according to an embodiment of the invention will be described using FIGS. 1 and 2.
[0016] As shown in FIGS. 1 and 2, an electrostatic coating apparatus 1 according to an embodiment of the invention is an apparatus for performing electrostatic coating on a coating subject (a vehicle body 2) to be subjected to coating, and includes a coating gun 3, a robot arm 4, a high voltage generation device 9, and so on. Note that in the example described in this embodiment, the electrostatic coating apparatus 1 is used in an application for coating the vehicle body 2 of an automobile, but the electrostatic coating apparatus according to the invention is not limited to this application.
[0017] The coating gun 3 is a device for spraying a coating onto the coating subject vehicle body 2, and includes a bell cap 3a, a ring electrode 3b, and so on. The coating gun 3 is a rotary atomization type coating device capable of rotating the bell cap 3a using driving means such as an air motor, not shown in the drawing, so that a fluid coating spread onto an inner surface of the bell cap 3a is atomized by centrifugal force.
[0018] As shown in FIG. 1, the robot arm 4 is constituted by a vertical arm 5 coupled rotatably to a base portion 7 by a lower portion thereof, and a horizontal arm 6 coupled rotatably to an upper portion of the vertical arm 5 by a rear end portion thereof. The coating gun 3, which is provided on a tip end portion of the horizontal arm 6, can be displaced relative to the vehicle body 2 by rotating the vertical arm 5 and the horizontal arm 6 about respective rotary fulcrums thereof.
[0019] Further, the horizontal arm 6 includes a first arm portion 6a, a second arm portion 6b, and a third arm portion 6c, wherein a coupling pipe 3e of the coating gun 3 is coupled to a tip end portion of the first arm portion 6a, the first arm portion 6a is coupled to a tip end portion of the second arm portion 6b, the second arm portion 6b is coupled to a tip end portion of the third arm portion 6c, and the vertical arm 5 is coupled rotatably to a base end portion of the third arm portion 6c.
[0020] Furthermore, two bending portions 6d, 6e are provided in the first arm portion 6a, and the first arm 6a is bent at the respective bending portions 6d, 6e. Thus, an angle of the coating gun 3 can be modified in a clockwise direction or a counterclockwise direction in FIGS. 1 and 2.
[0021] The coating gun 3 is attached to a tip end of the coupling pipe 3e, and the coupling pipe 3e is driven to rotate in an axial direction relative to the first arm portion 6a. The angle of the coating gun 3 can be modified about an axis of the coupling pipe 3e. Thus, the angle of the coating gun 3 relative to the vehicle body 2 can be set freely.
[0022] The high voltage generation device 9 is connected to the coating gun 3 and the robot arm 4. The high voltage generation device 9 generates high voltages that are applied to the coating gun 3 and the robot arm 4. The high voltage generation device 9 includes a voltage generation portion 21 serving as a site for generating a voltage and controlling the voltage, and a voltage boosting portion 22 serving as a site for boosting the voltage generated in the voltage generation portion 21.
[0023] In this embodiment, the voltage boosting portion 22 of the high voltage generation device 9 is disposed in an interior of the second arm portion 6b, and the voltage generation portion 21 is disposed on an exterior of the robot arm 4. A low voltage cable 23 is laid through the respective portions 6b, 6c of the robot arm 4 and the vertical arm 5 and led to the exterior from a midway point in the vertical arm 5. Thus, the voltage generation portion 21 and the voltage boosting portion 22 are connected by the low voltage cable 23.
[0024] Further, high voltage cables 10, 11 are laid through the respective portions 6a, 6b of the robot arm 4 and the interior of the coating gun 3 such that the voltage boosting portion 22 is connected respectively to the coating gun 3 and the robot arm 4 by the high voltage cables 10, 11. Thus, high voltages are applied to the coating gun 3 and the robot arm 4.
[0025] By causing the high voltage generation device 9 to apply an electrostatic high voltage having a negative polarity to the coating gun 3, coating molecules sprayed from the coating gun 3 can be charged to a negative polarity side. Electrostatic coating is then performed on the vehicle body 2 using an electrostatic field formed between the coating charged to the negative polarity side and the grounded (i.e. having a potential of 0 V) vehicle body 2.
[0026] As shown in FIG. 2, by causing the high voltage generation device 9 to apply an electrostatic high voltage to the coating gun 3, an electrostatic high voltage is also applied to the ring electrode 3b, which is conductive with the coating gun 3. As a result, an electrostatic field is formed in a radial shape from tip end portions of a plurality of needle-shaped electrodes 3c formed on the ring electrode 3b. A coating mist is electrostatically repulsed by this electrostatic field, and therefore the coating mist is prevented from adhering to the coating gun 3.
[0027] Furthermore, the high voltage generation device 9 is connected to the first arm portion 6a of the robot arm 4 such that a high voltage having an identical negative polarity to the voltage applied to the coating gun 3 is applied to the first arm portion 6a. By causing the high voltage generation device 9 to apply an electrostatic high voltage to the first arm portion 6a, an electrostatic high voltage is also applied to a ring electrode 8 that is conductive with the first arm portion 6a. As a result, an electrostatic field is formed in a radial shape from tip end portions of a plurality of needle-shaped electrodes 8a formed on the ring electrode 8. The coating mist is electrostatically repulsed by this electrostatic field, and therefore the coating mist is prevented from adhering to the first arm portion 6a.
[0028] Here, a difference occurs between the coating gun 3 and the first arm portion 6a in a charge of the coating mist floating on the periphery of the respective components. More specifically, a coating mist maintaining a high charge immediately after being sprayed from the coating gun 3 exists in a comparatively large amount on the periphery of the coating gun 3, whereas a coating mist that approaches the coating subject and so on after being sprayed from the coating gun 3 such that the charge thereof is emitted exists in a comparatively large amount on the periphery of the first arm portion 6a. Therefore, a potential for realizing effective electrostatic repulsion differs between the coating gun 3 and the first arm portion 6a. Accordingly, the high voltage applied to the first arm portion 6a preferably has a lower voltage than the high voltage applied to the coating gun 3.
[0029] In a conventional configuration, high voltages having different voltages are applied respectively to the coating gun 3 and the first arm portion 6a by connecting separate high voltage generation devices to the coating gun 3 and the first arm portion 6a. In other words, a high voltage generation device having a voltage generation portion and a voltage boosting portion is provided for the coating gun 3, and a high voltage generation device having a voltage generation portion and a voltage boosting portion is provided for the first arm portion 6a. In the electrostatic coating apparatus 1 according to this embodiment, however, high voltages having two different voltages can be output by the high voltage generation device 9 including only one voltage generation portion and one voltage boosting portion.
[0030] Next, a first embodiment of the high voltage generation device provided in the electrostatic coating apparatus according to the invention will be described in further detail using FIGS. 3 to 5. As shown in FIG. 3, a high voltage generation device 9X serving as the high voltage generation device 9 according to the first embodiment includes the voltage generation portion 21, the voltage boosting portion 22, the low voltage cable 23, and so on.
[0031] The voltage generation portion 21 is a site for generating voltages serving as the basis of the high voltages applied to the coating gun 3 and the robot arm 4, and includes a power supply portion 27, an amplifier 28, a central processing unit (CPU) 29, a random access memory (RAM) 30, a relay 31, a push-pull oscillation device 32, a voltage sensor 33, a current sensor 34, band pass filters 35, 36, and so on.
[0032] The voltage boosting portion 22 is a site for boosting the voltage generated by the voltage generation portion 21, and includes a high voltage transformer 24, a Cockcroft-Walton circuit (CW circuit) 25 serving as a rectifier and a multiplier for generating a high voltage and constituted by a combination of a plurality of capacitors, diodes, and the like, and so on. Further, as shown in FIG 4, the high voltage transformer 24 includes a primary winding 24a and a secondary winding 24b, and the CW circuit 25 is connected to the secondary winding 24b side.
[0033] As shown in FIGS. 3 and 4, the voltage generation portion 21 includes an output terminal 21a for outputting an operating voltage to a center phase (a CT phase) of the primary winding 24a, an output terminal 21b for outputting a drive signal to a drive A phase (a DA phase) of the primary winding 24a, and an output terminal 21c for outputting a drive signal to a drive B phase (a DB phase) of the primary winding 24a. Further, the voltage generation portion 21 includes an input terminal 21d for inputting a current feedback signal (an IM signal) indicating an overall generated current value of the CW circuit 25 to the CPU 29, an input terminal 21e for inputting a voltage feedback signal (a VM signal) indicating a high voltage value following boosting by the CW circuit 25 to the CPU, a ground terminal 21f for grounding the voltage generation portion 21, and so on.
[0034] The voltage boosting portion 22 includes an input terminal 22a connected to the CT phase of the primary winding 24a of the high voltage transformer 24, an input terminal 22b connected to the DA phase of the primary winding 24a, and an input terminal 22c connected to the DB phase of the primary winding 24a. Further, the voltage boosting portion 22 includes an output terminal 22d for outputting the IM signal indicating the overall generated current value of the CW circuit 25, an output terminal 22e for outputting the VM signal indicating the high voltage value following boosting by the CW circuit 25, a ground terminal 22f for grounding the CW circuit 25, and so on.
[0035] Furthermore, in the high voltage generation device 9X according to this embodiment, a voltage boosting portion 22X according to the first embodiment may be employed as the voltage boosting portion 22. In the voltage boosting portion 22X, the CW circuit 25 is connected to the ground terminal 22f such that a charge charged to the coating gun 3 and so on is released to the earth. A bleeder resistor 26 for suppressing a leak current is provided on a grounding line connecting the CW circuit 25 to the ground terminal 22f. Moreover, in the voltage boosting portion 22X, high voltage output terminals 22g, 22h of two systems are provided as terminals for outputting high voltages generated by the CW circuit 25.
[0036] The low voltage cable 23 is a bundle of various cables for electrically connecting the voltage generation portion 21 to the voltage boosting portion 22X, and is constituted by a CT input line 23a, a DA input line 23b, a DB input line 23c, an IM signal line 23d, a VM signal line 23e, a common line 23f, and so on.
[0037] The CT input line 23a is a cable for inputting the operating voltage generated by the voltage generation portion 21 into the CT phase of the primary winding 24a, and is connected between the output terminal 21a of the voltage generation portion 21 and the input terminal 22a of the voltage boosting portion 22X.
[0038] The DA input line 23b is a cable for inputting the drive signal generated by the voltage generation portion 21 into the DA phase of the primary winding 24a, and is connected between the output terminal 21b of the voltage generation portion 21 and the input terminal 22b of the voltage boosting portion 22X.
[0039] The DB input line 23c is a cable for inputting the drive signal generated by the voltage generation portion 21 into the DB phase of the primary winding 24a, and is connected between the output terminal 21c of the voltage generation portion 21 and the input terminal 22c of the voltage boosting portion 22X.
[0040] The IM signal line 23d is a cable for inputting the IM signal generated by the voltage boosting portion 22X into the CPU 29, and is connected between the input terminal 21d of the voltage generation portion 21 and the output terminal 22d of the voltage boosting portion 22X.
[0041] The VM signal line 23e is a cable for inputting the VM signal generated by the voltage boosting portion 22X into the CPU 29, and is connected between the input terminal 21 e of the voltage generation portion 21 and the output terminal 22e of the voltage boosting portion 22X. [0042] Further, the common line 23f is a cable for grounding the voltage generation portion 21 and the voltage boosting portion 22X to the earth and setting a common reference potential of 0 V, and is connected between the ground terminal 21f of the voltage generation portion 21 and the ground terminal 22f of the voltage boosting portion 22X.
[0043] A manner in which the high voltage generation device 9 generates a high voltage will now be described with reference to FIGS. 3 and 4. The voltage generation portion 21 generates the operating voltage by having the amplifier 28 regulate an output voltage generated by the power supply portion 27 in accordance with a command value from the CPU 29. The operating voltage generated in this case is measured by the voltage sensor 33 and the current sensor 34 provided on an operating voltage supply line. The measured value is fed back to the CPU 29, whereupon the CPU 29 regulates the operating voltage to match the command value.
[0044] Further, the IM signal and the VM signal are fed back to the CPU 29, and the CPU 29 determines the command value to be issued from the CPU 29 to the amplifier 28 through calculation on the basis of the respective feedback signals, conditions stored in the RAM 30, and so on. The IM signal, VM signal, and so on are input into the CPU 29 via the band pass filters 35, 36, and so on.
[0045] The voltage generation portion 21 generates the drive signals to be input into the respective drive phases of the primary winding 24a in accordance with a command value from the CPU 29 using the push-pull oscillation device 32. Further, the IM signal and the VM signal are fed back to the CPU 29, and the CPU 29 determines the command value to be issued from the CPU 29 to the push-pull oscillation device 32 through calculation on the basis of the respective feedback signals, the conditions stored in the RAM 30, and so on.
[0046] With this configuration, a predetermined alternating current voltage can be supplied to the primary winding 24a of the high voltage transformer 24. The CW circuit 25 connected to the secondary winding 24b can then boost the operating voltage supplied to the primary winding 24a to a predetermined magnification corresponding to a number of connection stages of the capacitors and diodes, and as a result, a direct current high voltage having a predetermined voltage value can be generated between points A and B of the CW circuit 25 in FIG 4.
[0047] In the voltage boosting portion 22X, one high voltage output terminal 22g of the output terminals 22g, 22h of the two systems connected to an output point B is a terminal for outputting the high voltage to be applied to the coating gun 3. The high voltage output terminal 22g and the coating gun 3 are connected by the high voltage cable 10.
[0048] The other high voltage output terminal 22h is a terminal for outputting the high voltage to be applied to the robot arm 4 (more specifically, the first arm portion 6a). A resistance portion 37 is connected to the high voltage output terminal 22h by a high voltage cable 12 such that the high voltage is applied to the first arm portion 6a via the resistance portion 37. Further, a resistance portion 37X according to the first embodiment may be employed in the high voltage generation device 9X as the resistance portion 37.
[0049] The resistance portion 37 is a site that serves to regulate the high voltage boosted by the voltage boosting portion 22 to a suitable voltage for application to the robot arm 4, and includes a resistance body 38. In the resistance portion 37X according to the first embodiment, a resistance body 38X according to the first embodiment, which is constituted by a plurality of resistors 38a (five in this embodiment) connected in series by a plurality of connection terminals 40 to 45 (six in this embodiment), is provided as the resistance body 38.
[0050] The connection terminal 40 disposed at one end portion of the plurality of resistors 38a connected in series is connected to an input terminal 37a of the resistance portion 37X, while the connection terminal 45 disposed at the other end portion is connected to a ground terminal 37c of the resistance portion 37X. The input terminal 37a is connected to the high voltage output terminal 22h of the voltage boosting portion 22X by the high voltage cable 12, and the ground terminal 37c is connected to the earth. Further, a contact portion 39 is connected to one of the connection terminals 40 to 44 forming the resistance body 38X. The contact portion 39 is connected to an output terminal 37b of the resistance portion 37X. The output terminal 37b of the resistance portion 37X and the robot arm 4 are connected by the high voltage cable 11.
[0051] An applied voltage suitable for application to the robot arm 4 is extracted from the contact portion 39 connected to one of the connection terminals 40 to 44, whereupon a high voltage is output from the output terminal 37b and applied to the robot arm 4.
[0052] In this embodiment, for example, five identical resistors (i.e. resistors having identical resistance values) are connected in series. When a value of a voltage at the output point B (in other words, a voltage output from the high voltage output terminal 22h) is set at 100%, an output voltage in a case where the contact portion 39 is connected to the connection terminal 41 shown in FIG 4 takes a voltage value of 80% of the voltage at the output point B. Similarly, output voltages in cases where the contact portion 39 is connected similarly to the other connection terminals 42, 43, 44 take voltage values of 60%, 40%, and 20% of the voltage at the output point B, respectively. Further, when the contact portion 39 is connected to the connection terminal 40, the output voltage takes an identical voltage value (i.e. 100%) to the voltage at the output point B.
[0053] Hence, in the electrostatic coating apparatus 1 according to an embodiment of the invention, the resistance body 38X is constituted by the plurality of resistors 38a connected in series, and the output terminal 37b is connected to one of the connection terminals 40 to 44 connecting the respective resistors 38a. Hence, with this simple configuration, the value of the high voltage applied to the robot arm 4 can be modified easily.
[0054] Note that in this embodiment, the resistance body 38X is formed by connecting the five identical resistors 38a (i.e. resistors having identical resistance values) in series. However, the configuration of the resistance body 38X is not limited by the number of resistors. For example, the resistance body 38X may be formed from a plurality of resistors having different resistance values so that the value of the output high voltage can be regulated to an even more suitable voltage for application to the robot arm 4.
[0055] Further, in this embodiment, with the high voltage outputs output from the voltage boosting portion 22 being formed as two systems, the resistance portion 37 is connected to the high voltage output terminal 22h corresponding to the robot arm 4. However, when a further site is to be prevented from becoming soiled in addition to the robot arm 4, high voltages of three or more systems may be output from the voltage boosting portion 22 and the resistance portion 37 may be connected to each additional high voltage output system.
[0056] A second embodiment of the high voltage generation device 9X according to the first embodiment, in which the configuration of the resistance portion 37 is modified, will now be described using FIG 5. As shown in FIG 5, in the high voltage generation device 9X according to this embodiment, a resistance portion 37Y according to the second embodiment is employed as the resistance portion 37 connected to the voltage boosting portion 22X.
[0057] The resistance portion 37Y differs from the resistance portion 37X according to the first embodiment, described above, in that a resistance body 38Y according to the second embodiment is used as the resistance body 38. Note that all other configurations of the resistance portion 37Y are identical to their counterparts in the resistance portion 37X according to the first embodiment.
[0058] The resistance portion 37 is a site that serves to regulate the high voltage boosted by the voltage boosting portion 22 to a suitable voltage for application to the robot arm 4. In the resistance portion 37Y according to the second embodiment, a single variable resistor 38b is used as the resistance body 38. The variable resistor 38b includes an input terminal 46 and a ground terminal 47. A movable contact portion 48, a contact position of which can be modified as desired, is provided at a midway point on an internal resistance 38c connecting the input terminal 46 and the ground terminal 47. A resistance value between the input terminal 46 and the movable contact portion 48 can be modified as desired by modifying the position of the movable contact portion 48 relative to the internal resistance 38c. [0059] The input terminal 46 of the variable resistor 38b is connected to the input terminal 37a of the resistance portion 37Y. Further, the ground terminal 47 is connected to the ground terminal 37c of the resistance portion 37Y. The input terminal 37a is connected to the high voltage output terminal 22h of the voltage boosting portion 22X, and the ground terminal 37c is connected to the earth. Furthermore, in the variable contact portion 48, the output terminal 37b of the resistance portion 37Y connected to the output terminal 37b of the resistance portion 37Y is connected to the robot arm 4 by the high voltage cable 11.
[0060] An applied voltage is regulated to a desired voltage by the variable resistor 38b, whereupon a high voltage suitable for application to the robot arm 4 is output from the output terminal 37b and applied to the robot arm 4.
[0061] In this embodiment, for example, when the value of the voltage at the output point B (in other words, the voltage output from the high voltage output terminal 22h) is set at 100%, an applied voltage can be extracted from the movable contact portion 48 shown in FIG 5 at a voltage value between 0 and 100% in accordance with an arrangement position of the movable contact portion 48. In other words, with the variable resistor 38b, the voltage output from the high voltage output terminal 22h can be extracted while being varied continuously between 0 and 100%.
[0062] Hence, in the electrostatic coating apparatus 1 according to an embodiment of the invention, the resistance body 38Y can be formed from the variable resistor 38b in which the resistance value between the input terminal 37a and the output terminal 37b is variably set. Hence, with this simple configuration, the value of the high voltage applied to the robot arm 4 can be modified more finely.
[0063] Next, a second embodiment of the high voltage generation device provided in the electrostatic coating apparatus according to the invention will be described using FIGS. 6 and 7. As described above, the high voltage generation device 9X according to the first embodiment includes the bleeder resistor 26 (see FIGS. 3 to 5). The bleeder resistor 26 is an electric resistance body provided on a grounding line for removing the charges charged to the coating gun 3 and the robot arm 4 in order to suppress a leak current when high voltage application by the high voltage generation device 9X is stopped.
[0064] To minimize the leak current during normal electrostatic coating, a resistor having a considerably larger resistance value than a resistor 22k provided between the output point B and the coating gun 3 is used as the bleeder resistor 26. Typically, for example, the resistor 22k has a resistance value of approximately 40 ΜΩ, whereas the bleeder resistor 26 has a resistance value of approximately 2 GQ.
[0065] In the resistance portion 37, one end portion of the resistance body 38 is connected to the input terminal 37a and the other end portion of the resistance body 38 is connected to the ground terminal 37c connected to the earth so that the high voltage input from the input terminal 37a can be regulated to a desired voltage value and output from the output terminal 37b. Hence, the resistance body 38 provided in the resistance portion 37 may serve as the bleeder resistor 26.
[0066] Therefore, in a high voltage generation device 9Y serving as the high voltage generation device 9 according to the second embodiment, as shown in FIG 6, the resistance portion 37 (more specifically, the resistance body 38) doubles as a bleeder resistor. Accordingly, the resistance portion 37 is built into the voltage boosting portion 22 rather than being provided separately to the voltage boosting portion 22, and disposed on the grounding line on which the bleeder resistor is conventionally disposed in place of the bleeder resistor.
[0067] As shown in FIGS. 6 and 7, in the high voltage generation device 9Y according to the second embodiment, a voltage boosting portion 22Y according to the second embodiment, in which the resistance portion 37 is inbuilt on the grounding line on which the bleeder resistor is conventionally disposed, is employed as the voltage boosting portion 22. In the voltage boosting portion 22Y, the resistance portion 37X according to the first embodiment, described above, is used as the resistance portion 37.
[0068] In the voltage boosting portion 22Y, the input terminal 37a of the resistance portion 37X is connected to the high voltage output terminal 22h and the ground terminal 37c is connected to the earth via the ground terminal 22f. Further, in the voltage boosting portion 22Y, the contact portion 39 connected to one of the respective connection terminals 40 to 44 constituting the resistance body 38X is connected to the output terminal 37b of the resistance portion 37X. The output terminal 37b of the resistance portion 37X and the robot arm 4 are connected by the high voltage cable 11.
[0069] Further, in the voltage boosting portion 22Y, an applied voltage suitable for application to the robot arm 4 is extracted from the contact portion 39 connected to one of the connection terminals 40 to 44, whereupon a high voltage is output from the output terminal 37b and applied to the robot arm 4.
[0070] The high voltage generation device 9Y employing the voltage boosting portion 22Y can be formed more compactly than the high voltage generation device 9X since the resistance portion 37 does not have to be provided separately. Further, the bleeder resistor can be omitted, and therefore the high voltage generation device 9 can be formed from a smaller number of components.
[0071] Another embodiment relating to the high voltage generation device 9Y according to the second embodiment, in which the configuration of the voltage boosting portion 22 is modified, will now be described using FIG 8. As shown in FIG 8, in the high voltage generation device 9Y according to this embodiment, a voltage boosting portion 22Z according to a third embodiment is employed as the voltage boosting portion 22. The voltage boosting portion 22Z uses the resistance portion 37Y according to the second embodiment, described above, as the resistance portion 37 built into the voltage boosting portion 22.
[0072] In the voltage boosting portion 22Z, the input terminal 37a of the resistance portion 37Y including the variable resistor 38b is connected to the high voltage output terminal 22h, and the ground terminal 37c is connected to the earth via the ground terminal 22f. Further, in the voltage boosting portion 22Z, the movable contact portion 48 is connected to the output terminal 37b of the resistance portion 37Y. The output terminal 37b of the resistance portion 37Y and the robot arm 4 are connected by the high voltage cable 11. [0073] Further, in the voltage boosting portion 22Z, an applied voltage is regulated to a desired voltage by the variable resistor 38b, whereupon a high voltage suitable for application to the robot arm 4 is output from the output terminal 37b and applied to the robot arm 4.
[0074] Hence, in the respective voltage boosting portions 22Y, 22Z of the electrostatic coating apparatus 1 according to an embodiment of the invention, the respective resistance bodies 38X, 38Y double as bleeder resistors (the conventional bleeder resistor 26) provided on an earth path of the voltage boosting portions 22Y, 22Z in order to reduce a leak current. With this configuration, the high voltage generation device 9 can be formed more compactly.
[0075] Further, the electrostatic coating apparatus 1 according to an embodiment of the invention includes: the coating gun 3 that sprays the coating; the robot arm 4 that supports the coating gun 3 displaceably; and the high voltage generation device 9 (the high voltage generation device 9X or the high voltage generation device 9Y) that generates high voltages to be applied to the coating gun 3 and the robot arm 4, wherein the high voltage generation device 9 includes: the voltage boosting portion 22 (the respective voltage boosting portions 22X, 22Y, 22Z) for boosting a voltage, which includes the high voltage output terminals 22g, 22h serving respectively as first and second output portions for outputting the high voltages; and the resistance portion 37 (the resistance portion 37X or the resistance portion 37Y) that includes the input terminal 37a into which the high voltages are input, the ground terminal 37c grounded to the earth, the electric resistance body 38 (the resistance body 38X or the resistance body 38Y) that connects the input terminal 37a and the ground terminal 37c, and the contact portion 39 or the movable contact portion 48 that forms a contact in an intermediate position of the resistance body 38 between the input terminal 37a and the ground terminal 37c, and wherein the high voltage output terminal 22g is connected to the coating gun 3, the high voltage output terminal 22h is connected to the input terminal 37a of the resistance portion 37, and the output terminal 37b of the resistance portion 37 or the movable contact portion 48 is connected to the robot arm 4. With this configuration, desired high voltages can be applied respectively to the coating gun 3 and the robot arm 4 by the simply configured high voltage generation device 9 including only the single voltage boosting portion 22, and as a result, the electrostatic coating apparatus 1 can be provided compactly and inexpensively.
[0076] Hence, with the electrostatic coating apparatus 1 according to an embodiment of the invention, two sites to be subjected to soiling prevention measures, namely the coating gun 3 and the robot arm 4, can be dealt with by the single voltage boosting portion 22. Therefore, leeway can be generated in a space for housing the voltage boosting portion 22 and the low voltage cable 23 in the robot arm 4, and a number of internal wires can be reduced. As a result, a wire laying operation can be simplified, and maintenance and management can be realized easily. Further, with the electrostatic coating apparatus 1 according to an embodiment of the invention, the robot arm 4 can be made slimmer, and therefore a more compact apparatus configuration can be realized. As a result, a manufacturing cost of the electrostatic coating apparatus can be reduced and so on.

Claims

CLAIMS: 1. An electrostatic coating apparatus comprising:
a coating gun that sprays a coating;
a robot arm that supports the coating gun displaceably; and
a high voltage generation device that generates high voltages to be applied to the coating gun and the robot arm,
wherein the high voltage generation device comprises:
a voltage boosting portion that boosts a voltage and that includes a first output portion and a second output portion for outputting the high voltages; and
a resistance portion that includes an input terminal, into which the high voltages are inputted, a ground terminal grounded to an earth, an electric resistance body that connects the input terminal and the ground terminal, and a contact portion that forms a contact in an intermediate position of the resistance body between the input terminal and the ground terminal, and
wherein the first output portion is connected to the coating gun, the second output portion is connected to the input terminal of the resistance portion, and the contact portion of the resistance portion is connected to the robot arm.
2. The electrostatic coating apparatus according to claim 1, wherein the resistance body includes a bleeder resistor provided on an earth path of the voltage boosting portion to reduce a leak current.
3. The electrostatic coating apparatus according to claim 1 or 2, wherein the resistance body is constituted by a plurality of resistors connected in series, and
the contact portion is connected to any one of connection terminals respectively connecting the plurality of resistors.
4. The electrostatic coating apparatus according to claim 1 or 2, wherein the resistance body is constituted by a variable resistor in which a resistance value between the input terminal and the contact portion is variably set.
PCT/IB2011/002013 2010-09-02 2011-09-01 Electrostatic coating apparatus Ceased WO2012028942A2 (en)

Applications Claiming Priority (2)

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JP2010-197099 2010-09-02
JP2010197099A JP2012050949A (en) 2010-09-02 2010-09-02 Electrostatic coating apparatus

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US10315205B2 (en) 2013-01-30 2019-06-11 Carlisle Fluid Technologies, Inc. Electrostatic coater and electrostatic coating method

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JP7498763B2 (en) * 2021-12-22 2024-06-12 シーエフティー エルエルシー Electrostatic sprayer, rotary atomizing head incorporated therein, and method of manufacturing the same

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Publication number Priority date Publication date Assignee Title
US9061292B2 (en) 2010-09-27 2015-06-23 Toyota Jidosha Kabushiki Kaisha Electrostatic coating gun
US10315205B2 (en) 2013-01-30 2019-06-11 Carlisle Fluid Technologies, Inc. Electrostatic coater and electrostatic coating method
US11135605B2 (en) 2013-01-30 2021-10-05 Ransburg Industrial Finishing K.K. Electrostatic coater and electrostatic coating method

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