JP2012071224A - Electrostatic coating device and grounding condition inspection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrostatic coating device and a grounding condition inspection method, wherein the grounding condition can be inspected in a short period of time without using a dedicated device for inspecting the grounding condition.SOLUTION: The electrostatic coating device 1 includes: a coating gun 3 spraying paint to an object 2; a robot arm 4 displaceably supporting the coating gun 3; and a high-voltage generating device 9 generating high voltage to be applied to the coating gun 3 and adjusting the generated high voltage in such a manner that a discharge current generated between the coating gun 3 and the object 2 is detected. While paint is not sprayed toward the object 2 by the coating gun 3, an electric field is formed from the coating gun 3 toward the object 2 to charge the object 2 with electric charge, and, while high voltage is not applied to the coating gun 3 by the high-voltage generating device 9, the high-voltage generating device 9 is used to detect the discharge current generated between the coating gun 3 and the object 2 on the basis of the electric charge that is charged on the object 2.

Description

  The present invention relates to a technique for an electrostatic coating apparatus, and more particularly to a technique for inspecting a ground state for an object to be coated having low conductivity.

Conventionally, when electrostatic coating is performed on a low conductivity part such as a resin part, a conductive primer, which is a material for imparting conductivity to the part, is applied to the painted surface, and the conductivity is improved. A technique for performing electrostatic coating after securing is known. After applying the conductive primer, it is necessary to confirm that the conductivity is ensured (that is, whether it is grounded to the earth), so that the coating for performing electrostatic coating on the part is performed. The line is generally provided with a dedicated device for confirming the ground state.
As an apparatus for confirming such a ground state, for example, the technique is disclosed in Patent Document 1 shown below and is known.

  In the prior art disclosed in Patent Document 1, a charge application device that applies a charge in a non-contact state with respect to a painted surface, and a charge amount on the painted surface of an object to be coated in a non-contact state. A ground state of a painted surface of an object to be electrostatically coated, comprising: a charge amount measuring sensor to be measured; and a determination device for determining whether or not the charge amount measured by the charge amount measuring sensor is within a predetermined range. An apparatus for inspecting is disclosed.

JP-A-2005-58998

  However, the inspection apparatus according to the related art disclosed in Patent Document 1 is a dedicated apparatus for confirming the ground state, and it is necessary to separately secure a process for inspecting the ground state. This has been a factor in causing an increase in the length of paint, a prolonged painting time, and an increase in the cost of painting equipment.

  The present invention has been made in view of such a current problem, and without using a dedicated device for inspecting the ground state, the electrostatic coating apparatus and the ground state capable of inspecting the ground state in a short time The purpose is to provide an inspection method.

  The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described.

  That is, in claim 1, a paint gun for spraying paint toward an object to be coated, a robot arm that displaceably supports the paint gun, and a high voltage applied to the paint gun are generated, A high voltage generator for adjusting a high voltage to be generated by detecting a discharge current generated when an electric field is formed between the coating gun and the object to be coated, and an electrostatic coating apparatus comprising: In the state where the paint is not sprayed toward the object to be coated by the paint gun, an electrostatic field is formed from the paint gun toward the object to be charged, and the object is charged with electric charges. A discharge generated between the coating gun and the object to be coated by a charge charged on the object to be coated in a state where a high voltage is not applied to the coating gun by the high voltage generator. Current It is intended to leave.

  In Claim 2, it comprises the first and second electrostatic coating devices, forming an electrostatic field from the coating gun of the first electrostatic coating device toward the object to be coated, The object to be coated is charged with electric charge, and the high voltage generator of the second electrostatic coating apparatus is charged with the electric charge charged to the object to be coated. The discharge current generated between the object and the object to be coated is detected.

  4. The coating gun and the coating object according to claim 3, wherein the high-voltage generator causes the charge to be applied to the object to be coated in a state where a high voltage is not applied to the coating gun by the high-voltage generator. When detecting the discharge current generated between the object and the object, the distance between the coating gun and the object to be coated is made smaller than the distance of the object during electrostatic coating.

  5. The method according to claim 4, wherein when an electrostatic field is formed from the coating gun toward the object to be charged and the object is charged with an electric charge, the displacement distance of the coating gun is set as the coating distance during electrostatic coating. This is smaller than the displacement distance of the gun.

  6. The coating gun and the coating object according to claim 5, wherein the high voltage generator causes the charge to be applied to the object to be coated in a state where a high voltage is not applied to the coating gun by the high voltage generator. When detecting a discharge current generated between an object and an object, the displacement distance of the coating gun is made smaller than the displacement distance of the coating gun during electrostatic painting.

  In Claim 6, after apply | coating a conductive primer with respect to a to-be-coated object, while applying a high voltage to the to-be-coated object, measuring the electric potential in the surface of the to-be-coated object, A ground state inspection method for inspecting a state, wherein a high voltage is applied to the object to be coated and an electric potential on the surface of the object to be coated is measured using an electrostatic coating apparatus.

  In Claim 7, While applying the high voltage to the said to-be-coated object by the said 1st electrostatic coating apparatus using the said 1st and 2nd electrostatic coating apparatus, the said 2nd said electrostatic coating An apparatus measures the potential on the surface of the object to be coated.

  As effects of the present invention, the following effects can be obtained.

  According to the first aspect of the present invention, it is possible to inspect the ground state of the object to be coated without using a dedicated device. This also makes it possible to shorten the coating line, shorten the inspection time, reduce the cost of the coating equipment, and the like.

  According to the second aspect of the present invention, the waiting time after the charge is applied can be shortened to further shorten the inspection time.

  According to the third aspect, the surface potential of the object to be coated can be detected more reliably, and the inspection accuracy of the ground state can be improved.

  The inspection time can be shortened by shortening the charge application time.

  The inspection time can be shortened by shortening the detection time of the surface potential.

  According to the sixth aspect of the present invention, it is possible to inspect the ground state of the object to be coated without using a dedicated device. This also makes it possible to shorten the coating line, shorten the inspection time, reduce the cost of the coating equipment, and the like.

  According to the seventh aspect of the present invention, the waiting time after the charge is applied can be shortened to further shorten the inspection time.

The schematic diagram which shows the whole structure of the electrostatic coating apparatus which concerns on one Embodiment of this invention. The schematic diagram which shows the formation condition of the electric field with respect to a to-be-coated object from the electrostatic coating apparatus which concerns on one Embodiment of this invention. The schematic diagram which shows the structure of the high voltage generator in the electrostatic coating apparatus which concerns on one Embodiment of this invention. The schematic diagram which shows the test | inspection condition of the earth state by the electrostatic coating apparatus (when one unit is used) which concerns on one Embodiment of this invention, (a) The schematic diagram which shows the application condition of a voltage, (b) The detection condition of surface potential FIG. The schematic diagram which shows the condition of the time change of surface potential. The inspection flowchart which shows the flow of the inspection method of the ground state by the electrostatic coating apparatus (when one unit is used) which concerns on one Embodiment of this invention. The schematic diagram which shows the displacement condition of the coating gun with respect to the to-be-coated object in the electrostatic coating apparatus which concerns on one Embodiment of this invention, (a) The displacement condition at the time of the test | inspection of a ground state (at the time of voltage application and the detection of surface potential) (B) The schematic diagram which shows the displacement condition at the time of electrostatic coating. Schematic diagram showing the overall configuration of the coating line, (a) Schematic diagram showing the configuration of the coating line when the ground state is inspected using the electrostatic coating apparatus according to one embodiment of the present invention, (b) conventional The schematic diagram which shows the structure of the coating line in the case of performing the test | inspection of an earth state using an inspection exclusive apparatus. The schematic diagram which shows the test | inspection condition of the ground state by the electrostatic coating apparatus (when using 2 units | sets) which concerns on one Embodiment of this invention. The inspection flowchart which shows the flow of the inspection method of the ground state by the electrostatic coating apparatus (when 2 units | sets are used) which concerns on one Embodiment of this invention.

Next, embodiments of the invention will be described.
First, the overall configuration of an electrostatic coating apparatus according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2.
As shown in FIGS. 1 and 2, the electrostatic coating apparatus 1 according to an embodiment of the present invention is a component such as a resin bumper and has a property of low conductivity so that electrostatic coating cannot be performed as it is. A coating apparatus capable of performing electrostatic coating on an object 2 to be coated, which includes a coating gun 3, a robot arm 4, a high voltage generator 9, and the like.

The coating gun 3 is a device for spraying paint onto the article 2 and includes a bell cup 3a.
The coating gun 3 is a rotary atomizing type coating device that can rotate the bell cup 3a by a driving means such as an air motor (not shown) to atomize the fluid paint spread on the inner surface of the bell cup 3a by centrifugal force. It is.

  As shown in FIG. 1, the robot arm 4 has an upper and lower arms 5 rotatably connected to a base portion 7 at a lower portion thereof, and a horizontal end whose rear end portion is rotatably connected to an upper portion of the upper and lower arms 5. The coating gun 3 provided at the front end of the horizontal arm 6 can be displaced with respect to the object 2 by rotating the upper and lower arms 5 and the horizontal arm 6 at respective rotation fulcrums. It is configured as possible.

  Further, the horizontal arm 6 has a first arm portion 6a to which the connecting cylinder 3b of the coating gun 3 is connected at a tip portion thereof, a second arm portion 6b to which the first arm portion 6a is connected to a tip portion thereof, The second arm portion 6b is connected to the tip portion, and the third arm portion 6c is connected to the rear end portion of the upper and lower arms 5 so as to be rotatable.

  The first arm portion 6a is provided with two refracting portions 6d and 6e, and the first arm portion 6a is refracted at each of the refracting portions 6d and 6e. However, the angle can be changed clockwise or counterclockwise in FIGS. 1 and 2.

  The connecting cylinder 3b to which the coating gun 3 is attached at the tip is configured to be rotationally driven in the axial direction with respect to the first arm portion 6a, and the coating gun 3 has an angle around the axis of the connecting cylinder 3b. Can be changed. Thereby, it is set as the structure which can set the angle with respect to the to-be-coated object 2 of the painting gun 3 freely.

Further, a high voltage generator 9 is electrically connected to the coating gun 3.
As shown in FIGS. 1 and 2, the high voltage generator 9 is a device for generating a high voltage to be applied to the coating gun 3, and generates a voltage and is a part for controlling the voltage. 21 and a voltage booster 22 which is a part for boosting the voltage generated in the voltage generator 21.

  In the present embodiment, in the high voltage generator 9, the voltage booster 22 is disposed inside the second arm 6 b, and the voltage generator 21 is disposed outside the robot arm 4. Then, the low voltage cable 23 is wired in the parts 6b and 6c and the upper and lower arms 5 of the robot arm 4, and the low voltage cable 23 is pulled out from the middle of the upper and lower arms 5, and the voltage generator 21 is generated by the low voltage cable 23. And the voltage booster 22 are connected.

  Further, the high voltage cable 10 is wired inside each part 6a, 6b of the robot arm 4 and the painting gun 3, and the voltage boosting unit 22 is connected to the painting gun 3 by the high voltage cable 10. The voltage is applied to the coating gun 3.

The coating gun 3 can charge the paint particles sprayed from the coating gun 3 to the negative electrode side by applying a negative electrostatic high voltage by the high voltage generator 9.
Then, an electrostatic field (hereinafter referred to as an electric field E) as shown in FIG. 2 is formed between the paint charged on the negative electrode side and the workpiece 2 grounded (that is, the potential is 0 V). E is used to perform electrostatic coating on the article 2 to be coated.

Next, the high voltage generator 9 provided in the electrostatic coating apparatus 1 will be described in more detail with reference to FIG.
As shown in FIG. 3, the high voltage generator 9 includes a voltage generator 21, a voltage booster 22, a low voltage cable 23, and the like.

  The voltage generator 21 is a part for generating a voltage that becomes a high voltage to be applied to the coating gun 3 and the robot arm 4. The power generator 27, the amplifier 28, the CPU 29, the RAM 30, the relay 31, the push A pull oscillator 32, a voltage sensor 33, a current sensor 34, band pass filters 35 and 36, and the like are provided.

The voltage booster 22 is a part for boosting the voltage generated by the voltage generator 21, and is a high voltage transformer 24, a rectifier and a multiplier for generating high voltage, and a combination of a plurality of capacitors, diodes, and the like. A configured Cockcroft Walton circuit (CW circuit) 25 and the like are provided.
The high voltage transformer 24 includes a primary winding 24a and a secondary winding 24b, and a CW circuit 25 is connected to the secondary winding 24b side.

The voltage generator 21 outputs an operating voltage for the center phase (hereinafter referred to as CT phase) of the primary winding 24a, and the drive A phase (hereinafter referred to as DA phase) of the primary winding 24a. ) And an output terminal 21c for outputting a drive signal for the drive B phase (hereinafter referred to as DB phase) of the primary winding 24a.
Further, the voltage generator 21 has an input terminal 21d for inputting a current feedback signal (hereinafter referred to as IM signal) indicating the total generated current value of the CW circuit 25 to the CPU 29, and the CW circuit 25 to the CPU. An input terminal 21e for inputting a voltage feedback signal (hereinafter referred to as a VM signal) indicating a high voltage value after boosting, a ground terminal 21f for grounding the voltage generator 21, and the like are provided.

The voltage boosting unit 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 a DB phase of the primary winding 24a. The input terminal 22c connected to is provided.
Further, the voltage boosting unit 22 outputs an IM signal indicating the total generated current value of the CW circuit 25, and an output for outputting a VM signal indicating a high voltage value boosted by the CW circuit 25. A terminal 22e, a ground terminal 22f for grounding the CW circuit 25, and the like are provided.

In the voltage booster 22, the CW circuit 25 is connected to the ground terminal 22f so that the electric charge charged in the coating gun 3 or the like is released to the ground. A bleeder resistor 26 for suppressing leakage current is provided on the ground line connecting the CW circuit 25 and the ground terminal 22f.
Further, the voltage booster 22 includes a high voltage output terminal 22g which is a terminal for outputting a high voltage generated by the CW circuit 25.

  The low voltage cable 23 is a bundle of various cables for electrically connecting the voltage generator 21 and the voltage booster 22, and includes a CT input line (CT) 23 a, a DA input line (DA) 23 b, and a DB input line. (DB) 23c, IM signal line (IM) 23d, VM signal line (VM) 23e, common line (COM) 23f, and the like.

  The CT input line 23a is a cable for inputting the operating voltage generated by the voltage generator 21 to the CT phase of the primary winding 24a. The CT input line 23a is connected to the output terminal 21a of the voltage generator 21 and the input terminal 22a of the voltage booster 22. Connected between.

  The DA input line 23b is a cable for inputting the drive signal generated by the voltage generator 21 to the drive A phase of the primary winding 24a. The DA input line 23b is an output terminal 21b of the voltage generator 21 and an input terminal 22b of the voltage booster 22. Connected between.

  The DB input line 23c is a cable for inputting the drive signal generated by the voltage generator 21 to the drive B phase of the primary winding 24a. The DB input line 23c is an output terminal 21c of the voltage generator 21 and an input terminal 22c of the voltage booster 22. Connected between.

  The IM signal line 23 d is a cable for inputting the IM signal generated by the voltage booster 22 to the CPU 29, and is connected between the input terminal 21 d of the voltage generator 21 and the input terminal 22 d of the voltage booster 22. .

  The VM signal line 23 e is a cable for inputting the VM signal generated by the voltage booster 22 to the CPU 29, and is connected between the input terminal 21 e of the voltage generator 21 and the input terminal 22 e of the voltage booster 22. .

  Further, the common line 23f is a cable for setting the common reference potential (0V) by grounding the voltage generating unit 21 and the voltage boosting unit 22 to the ground. The common line 23f is connected to the ground terminal 21f of the voltage generating unit 21 and the voltage boosting. It is connected between the ground terminals 22f of the section 22.

Here, the high voltage generation state by the high voltage generator 9 will be described with reference to FIG.
The voltage generation unit 21 adjusts the output voltage generated by the power supply unit 27 by the amplifier 28 in accordance with a command value from the CPU 29 to generate an operating voltage. The operating voltage generated here is measured by a voltage sensor 33 and a current sensor 34 provided on the operating voltage supply line, and the measured value is fed back to the CPU 29 so that the operating voltage matches the command value. It is adjusted by the CPU 29 so that

Further, the command value from the CPU 29 for the amplifier 28 is obtained by feeding back the above-mentioned IM signal or VM signal to the CPU 29 and performing calculations based on the feedback signals, conditions stored in the RAM 30, and the like by the CPU 29. Yes.
The IM signal, the VM signal, and the like are input to the CPU 29 via the band pass filters 35 and 36 and the like.

The voltage generator 21 generates a drive signal to be input to each drive phase of the primary winding 24a by the push-pull oscillation device 32 in accordance with a command value from the CPU 29.
Further, the command value from the CPU 29 for the push-pull oscillation device 32 is calculated based on the feedback signal, the conditions stored in the RAM 30, and the like by the above-described IM signal and VM signal being fed back to the CPU 29. Seeking by

  With such a configuration, a predetermined AC voltage can be supplied to the primary winding 24 a of the high voltage transformer 24. As a result, the CW circuit 25 connected to the secondary winding 24b boosts the operating voltage supplied to the supplied primary winding 24a to a predetermined magnification according to the number of connection stages of the capacitor and the diode. A DC high voltage having a predetermined voltage value can be generated between points αβ in FIG.

  Here, in the voltage booster 22, the output terminal 22 g connected to the output point β is a terminal for outputting a high voltage 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.

In addition, the high voltage generator 9 generates an electric field from the object to be coated to the painting gun 3 by the electric charge charged on the object to be coated in a state where no high voltage is applied to the painting gun 3, and the output When a discharge current flows from the terminal 22g toward the ground terminal 22f, a signal indicating the voltage of the discharge current (hereinafter referred to as an IS signal) is input to the VM signal line 23e.
When the IS signal is input to the CPU 29, the surface potential of the object to be coated can be detected by the CPU 29 performing a calculation based on the IS signal.

Next, as a first embodiment of the present invention, a method for measuring the surface potential when one electrostatic coating apparatus 1 is used will be described with reference to FIGS. 4 and 5.
As shown in FIG. 4 (a), the coating gun 3 is displaced by the robot arm 4 while the workpiece 2 is placed on the conveyor 11 connected to the ground and the conductive primer is applied, The distance between the bell cup 3a of the coating gun 3 and the article 2 to be coated is maintained at the distance L1. In this state, when a high voltage is applied to the coating gun 3 by the high voltage generator 9, an electric field E <b> 1 is formed between the bell cup 3 a and the workpiece 2, and an electric charge is applied to the workpiece 2. The

Thus, the time change of the surface potential in the article to be coated 2 when a charge is applied to the article to be coated 2 is as shown in FIG.
As shown in FIG. 5, when a high voltage generator 9 applies a charge from time t0 to time t1 to the object 2 having the surface potential V0, the surface potential of the object 2 at time t1 is V1. Become.

When the ground state of the article 2 is ideal, when the application of charge by the high-voltage generator 9 is stopped at time t1, after the time t1, as shown by a curve G1, The surface potential drops rapidly.
On the other hand, when the ground state of the article to be coated 2 is not appropriate, the surface potential of the article to be coated 2 gradually decreases after the time t1, as indicated by the curve G2.

When the ground state of the object 2 is ideal, the surface potential of the object 2 is lower than the preset potential Vk set in advance at the time t2 after the application of electric charge is stopped at the time t1. Is certainly smaller.
On the other hand, when the ground state of the article to be coated 2 is not appropriate, the surface potential of the article to be coated 2 is kept higher than the set potential Vk.

  Therefore, in the present embodiment, by detecting the surface potential of the article 2 to be coated at a time t2 that is a predetermined time after the application of charges by the high voltage generator 9 is stopped (that is, time t1), The quality of the ground state is judged.

Specifically, at time t2 shown in FIG. 5, the robot arm 4 compares the distance between the bell cup 3a of the coating gun 3 and the article 2 to the distance L1, as shown in FIG. 4B. The distance L2 is a short distance.
When the coating gun 3 (more specifically, the bell cup 3a) connected to the ground via the bleeder resistor 26 is brought close to the object to be coated 2, the charge charged on the object to be coated 2 becomes the bell cup. It is discharged toward 3a.
The electrostatic coating apparatus 1 according to the present embodiment is configured to measure the discharge current generated at this time, thereby detecting the surface potential of the article 2 and determining the quality of the ground state.

And the measurement of the said discharge current value can be performed by CPU29 with which the high voltage generator 9 is provided based on the said IS signal as mentioned above.
For this reason, in the present embodiment, the ground state can be inspected only by the electrostatic coating apparatus 1 without using any other dedicated inspection apparatus.

That is, the electrostatic coating apparatus 1 according to the first embodiment of the present invention includes a coating gun 3 for spraying paint toward an object 2 and a robot arm 4 that supports the coating gun 3 so as to be displaceable. Then, the high voltage to be applied to the coating gun 3 is generated, and the generated high voltage is adjusted by detecting the discharge current generated when the electric field E1 is formed between the coating gun 3 and the article 2 to be coated. The high voltage generator 9 is provided, and an electric field E1 is formed from the coating gun 3 toward the article 2 when the paint gun 3 is not spraying the paint toward the article 2 to be coated. Then, the object 2 was charged with electric charge, and the high voltage generator 9 charged the object 2 with no voltage applied to the coating gun 3 by the high voltage generator 9. Due to the electric charge, between the paint gun 3 and the workpiece 2 And it detects a discharge current generated.
With such a configuration, it is possible to inspect the ground state of the article 2 without using a dedicated device. This also makes it possible to shorten the coating line, shorten the inspection time, reduce the cost of the coating equipment, and the like.

Next, a ground state inspection method using the electrostatic coating apparatus 1 will be described with reference to FIGS.
As shown in FIGS. 4A and 4B, in the ground state inspection method using the electrostatic coating apparatus 1 shown in the present embodiment, only one existing electrostatic coating apparatus 1 is used, and the ground state is It is configured to perform the inspection.

  In the ground state inspection method using the electrostatic coating apparatus 1, first, as shown in FIG. 6, the conveyor 11 for transporting the article 2 is operated to apply the conductive primer to a predetermined inspection position. The object 2 to be coated is placed (S101). And when the to-be-coated object 2 is arrange | positioned in a predetermined test | inspection position, the conveyor 11 is stopped (S102).

Next, in a state where the object to be coated 2 is disposed at a predetermined inspection position, as shown in FIG. 4A, the high voltage generator 9 is turned on to apply a high voltage to the coating gun 3 (S103). ).
At this time, an electric field E <b> 1 is formed from the painting gun 3 toward the workpiece 2, and an electric charge is applied to the workpiece 2. At this time, the coating gun 3 does not spray the paint, and the distance between the coating gun 3 and the article 2 is the distance L1.

Next, the robot arm 4 displaces the coating gun 3 in a predetermined posture on a predetermined locus (S104).
As shown in FIG. 7 (a), when the range in which the charge can be applied by the coating gun 3 is a circular range S, a predetermined range is applied to each part while preventing a break in the range to which the charge is applied. The locus R is drawn at a constant speed from the state in which the center of the range S coincides with the start position P so that the charges are applied (that is, the charge application time to each part is substantially uniform). Displace the paint gun 3.

  As shown in FIG. 7B, the trajectory R has a range S compared to the trajectory Rs drawn by the coating gun 3 when the electrostatic coating apparatus 1 performs electrostatic coating on the workpiece 2. The displacement distance can be shortened by an amount that can reduce the overlap width. For this reason, the time required for applying the electric charge can be made shorter than the time required for performing electrostatic coating.

Then, the coating gun 3 is displaced until reaching the predetermined end position Q while the center of the range S draws the predetermined locus R while applying the electric charge to the workpiece 2 by the coating gun 3 (S105). When the center of the range S reaches the predetermined end position Q, the high voltage generator 9 is turned off (S106).
Thus far, the charge application process for the workpiece 2 by the electrostatic coating apparatus 1 is completed. From here, the process proceeds to a surface potential detection step by the electrostatic coating apparatus 1.

That is, in the electrostatic coating apparatus 1 according to the first embodiment of the present invention, when the electric field E1 is formed from the coating gun 3 toward the object 2 to be charged, the object 2 is charged. The displacement distance of the gun 3 is made smaller than the displacement distance of the coating gun 3 during electrostatic coating.
With such a configuration, it is possible to shorten the inspection time by reducing the charge application time.

  After the application of the electric charge to the object 2 is finished, the high voltage generator 9 waits for a predetermined time (that is, the time from time t1 to time t2 shown in FIG. 5) to elapse (S107). It is confirmed that the state is OFF (S108).

Next, the robot arm 4 displaces the coating gun 3 in a predetermined posture on a predetermined locus (S109).
In the present embodiment, when the distance between the coating gun 3 and the object to be coated 2 is the distance L1, the range in which a charge can be applied by the coating gun 3 and the distance between the coating gun 3 and the object to be coated 2 are the distance L2. Assuming that the range in which the surface potential can be detected by the coating gun 3 is the same in the range S, the locus at this time is the same as the locus R shown in FIG. The coating gun 3 is displaced at a constant speed from the start position P to the end position Q so as to detect the surface potential of the entire range so that there is no break in the detection range.
That is, the trajectory (displacement distance) of the coating gun 3 at the time of applying a charge and the trajectory (displacement distance) of the coating gun 3 at the time of measuring the surface potential can be set separately.

Under such a displacement condition, the surface potential is measured in a manner as shown in FIG. 4B while the coating gun 3 is displaced with respect to the workpiece 2 by the robot arm 4 (S110). And determination based on the measured surface potential (S111).
At this time, the distance between the coating gun 3 and the object to be coated 2 is set to a distance L2 that is smaller than the coating distance, and the surface potential is measured by bringing the coating gun 3 closer to the object to be coated 2, The surface potential is measured with higher accuracy.

That is, in the first embodiment of the present invention, the high voltage generator 9 causes the charge to be applied to the workpiece 2 in a state where a high voltage is not applied to the coating gun 3 by the high voltage generator 9. When detecting a discharge current generated when an electric field is formed between the coating gun 3 and the workpiece 2, the displacement distance of the coating gun 3 is compared with the displacement distance of the coating gun 3 during electrostatic coating. It is to make it smaller.
With such a configuration, it is possible to shorten the inspection time by shortening the detection time of the surface potential.

Moreover, in 1st embodiment of this invention, in the state which is not applying the high voltage to the coating gun 3 by the high voltage generator 9 by the high voltage generator 9, with the electric charge charged to the to-be-coated article 2, When detecting the discharge current generated between the coating gun 3 and the workpiece 2, the distance L2 between the coating gun 3 and the workpiece 2 is made smaller than the coating distance during electrostatic coating. .
With such a configuration, it is possible to more reliably detect the surface potential of the article 2 and improve the inspection accuracy of the ground state.

  This determination is made based on whether or not the measured surface potential is equal to or lower than a predetermined set potential Vk as shown in FIG. 5, and the measured surface potential value V2 is equal to or lower than the set potential Vk. If there is, it is determined that the ground state of the article 2 is good, and the determination is repeated until the position of the coating gun 3 reaches the predetermined end position Q (S112).

Alternatively, if the value of the measured surface potential V2 exceeds the set potential Vk, it is determined that the ground state of the article 2 is abnormal and the measurement is terminated (S114), and processing when there is an abnormality (S115). The content of the abnormality process here is, for example, a process for confirming the grounding state of the earth clip or the like on the workpiece 2 in which an abnormality is recognized.
If the abnormality process is completed, the determination that the state is abnormal is reset (S116).

Then, after the measurement of the surface potential is completed (S113) or after the abnormal state is reset (S116), the conveyor 11 is operated to remove the article 2 from the inspection position (S117).
The inspection of the ground state using the electrostatic coating apparatus 1 is thus completed.

That is, in the first embodiment of the present invention, after applying a conductive primer to the article 2 to be coated, a high voltage is applied to the article 2 to be measured and the potential on the surface of the article 2 is measured. A ground state inspection method for inspecting the ground state of an object to be coated 2, which uses an electrostatic coating apparatus 1 to apply a high voltage to the object 2 and measure the potential on the surface of the object 2 to be coated. To do.
With such a configuration, it is possible to inspect the ground state of the article 2 without using a dedicated device. This also makes it possible to shorten the coating line, shorten the inspection time, reduce the cost of the coating equipment, and the like.

  And the coating line in the case of performing the test | inspection of an earth state using the electrostatic coating apparatus 1 in this way becomes a structure as shown to Fig.8 (a). According to this configuration, since the earth check process and apparatus can be used, for example, as a base painting process and a painting apparatus, the earth check process is compared with the conventional painting line shown in FIG. Further, the apparatus can be omitted, and the painting line can be made compact.

Next, as a second embodiment of the present invention, a surface potential measurement method using two electrostatic coating apparatuses 1 will be described with reference to FIGS. 4, 5, and 9.
As shown in FIGS. 4 (a) and 4 (b), in the case of inspecting the ground state with one electrostatic coating apparatus 1, the process proceeds to the measurement of the surface potential unless the application of charges is completed. Can not do it. Therefore, in the present embodiment, the configuration is such that the inspection can be performed in a shorter time using the two adjacent electrostatic coating apparatuses 1 and 1.

As shown in FIG. 9, the first electrostatic coating device that is the first electrostatic coating device 1 in a state where the article 2 is placed on the conveyor 11 connected to the ground and the conductive primer is applied. A first coating gun 3X (hereinafter referred to as a first coating gun 3X) included in the first electrostatic coating apparatus 1X is obtained by a first robot arm 4X (hereinafter referred to as a first robot arm 4X) which is a 1X robot arm 4. The distance between the bell cup 3a and the workpiece 2 is kept at the distance L1.
In this state, when a high voltage is applied to the first coating gun 3X by the first high voltage generator 9X, which is the first high voltage generator 9 included in the first electrostatic coating apparatus 1X, An electric field E1 is formed between the object 2 and the object 2 to be charged.

As described above, the time change of the surface potential of the object to be coated 2 when the electric charge is applied to the object to be coated 2 is as shown in FIG.
That is, as shown in FIG. 5, when a charge is applied from time t0 to time t1 to the object 2 having the surface potential V0 by the first high voltage generator 9X, the surface of the object 2 at time t1. The potential is V1.

When the ground state of the article 2 is ideal, when the application of electric charges by the first high-voltage generator 9X is stopped at time t1, the object to be coated is shown as a curve G1 after time t1. The surface potential of 2 drops rapidly.
On the other hand, when the ground state of the article to be coated 2 is not appropriate, the surface potential of the article to be coated 2 gradually decreases after the time t1, as indicated by the curve G2.

When the ground state of the object 2 is ideal, the surface potential of the object 2 is lower than the preset potential Vk set in advance at the time t2 after the application of electric charge is stopped at the time t1. Is certainly smaller.
On the other hand, when the ground state of the article to be coated 2 is not appropriate, the surface potential of the article to be coated 2 is kept higher than the set potential Vk.

  In the present embodiment, the first electrostatic coating apparatus 1Y, which is the second electrostatic coating apparatus 1, is used for the part where the application of the electric charge by the first high voltage generator 9X is completed. The high-voltage generator 9X determines whether the ground state is good or not without waiting for the completion of the application of the charges. For this reason, the surface potential is detected before the time t2 when the application of all the charges ends. Is configured to start.

Specifically, for example, at the time t3 shown in FIG. 5, as shown in FIG. 9, the second robot arm 4Y provided in the second electrostatic coating apparatus 1Y includes the second included in the second electrostatic coating apparatus 1Y. The distance between the bell cup 3a of the second coating gun 3Y that is the coating gun 3 and the article 2 to be coated is held at a distance L2, which is a shorter distance than the distance L1.
Here, although the timing at time t3 is earlier than that at time t2, since the surface potential at this time is sufficiently smaller than the set potential Vk, surface potential V3 at time t3 shown in FIG. It is possible to determine the ground state using.

When the second coating gun 3Y (more specifically, the bell cup 3a) connected to the ground via the bleeder resistor 26 is brought close to the workpiece 2, the charge charged on the workpiece 2 is Discharge toward the bell cup 3a.
In the second electrostatic coating apparatus 1Y according to the present embodiment, by measuring the discharge current value, the surface potential of the article 2 is detected and the quality of the ground state is determined.

And the measurement of the said discharge current value can be performed by CPU29 with which the 2nd high voltage generator 9Y of the 2nd electrostatic coating apparatus 1Y is provided based on the said IS signal as mentioned above.
For this reason, in this embodiment, the ground state can be inspected by using the two existing electrostatic coating apparatuses 1X and 1Y without using any other dedicated inspection apparatus.

That is, in the second embodiment of the present invention, the first and second electrostatic coating apparatuses 1X and 1Y are provided, and the object 2 is applied from the first coating gun 3X of the first electrostatic coating apparatus 1X. The electric field E2 is formed toward the object 2 to charge the object 2 to be charged, and the second high voltage generator 9Y of the second electrostatic coating apparatus 1Y uses the electric charge charged to the object 2 to A discharge current generated between the second coating gun 3Y of the electrostatic coating apparatus 1Y and the workpiece 2 is detected.
With such a configuration, the waiting time after the charge is applied can be shortened, and the inspection time can be further shortened.

Next, a ground state inspection method using the two electrostatic coating apparatuses 1X and 1Y will be described with reference to FIGS.
As shown in FIG. 10, in the ground state inspection method using the two electrostatic coating apparatuses 1X and 1Y, first, the conveyor 11 for transporting the article to be coated 2 is actuated to a predetermined inspection position. The article 2 with the conductive primer applied is placed (S201). And when the to-be-coated object 2 is arrange | positioned in a predetermined test | inspection position, the conveyor 11 is stopped (S202).

  Next, in a state where the workpiece 2 is placed at a predetermined inspection position, the first high voltage generator 9X of the first electrostatic coating apparatus 1X is turned on, and the first coating in the first electrostatic coating apparatus 1X is performed. A high voltage is applied to the gun 3X (S203). At this time, as shown in FIG. 9, an electric field E <b> 1 is formed from the first coating gun 3 </ b> X toward the workpiece 2, and an electric charge is applied to the workpiece 2. At this time, spraying of the paint by the first coating gun 3X is not performed.

Next, the first robot arm 4X in the first electrostatic coating apparatus 1X displaces the first coating gun 3X in a predetermined posture on a predetermined locus (S204).
At this time, similarly to the case where only one electrostatic coating apparatus 1 is used, a range in which charges can be applied by the first coating gun 3X is set as a circular range S as shown in FIG. In such a case, a predetermined charge is applied to each part (that is, an application time of the charge to each part is substantially equal) while preventing a break in the range to which the charge is applied. The first coating gun 3X is displaced so as to draw a locus R at a constant speed from a state where the center coincides with the start position P.

  And from the time of the displacement of the 1st coating gun 3X by the 1st robot arm 4X being started, it transfers to the detection process of the surface potential by the 2nd electrostatic coating apparatus 1Y.

On the other hand, the charge application process by the first coating gun 3X is continued, and the first coating gun 3X is displaced to a predetermined end position Q while applying the charge to the article 2 (S205). When the first coating gun 3X reaches the predetermined end position Q, the first high voltage generator 9X is turned off (S206).
Thus far, the charge application process for the workpiece 2 by the first electrostatic coating apparatus 1X is completed.

Then, after a predetermined time (that is, the time from time t1 to time t3 shown in FIG. 5) has elapsed since the start of the displacement of the first coating gun 3X (S301), the second electrostatic coating is performed. The second robot arm 4Y of the apparatus 1Y displaces the second coating gun 3Y in the second electrostatic coating apparatus 1Y on a predetermined locus in a predetermined posture (S302).
That is, in this embodiment, it is possible to shift to the surface potential detection process at an early stage as compared with the case where only one electrostatic coating apparatus 1 is used.

  In addition, the trajectory for displacing the second coating gun 3Y by the second robot arm 4Y at this time is the same as that when only one electrostatic coating apparatus 1 is used, between the first coating gun 3X and the object 2 to be coated. The surface potential can be applied by the second coating gun 3Y when the distance can be applied by the first coating gun 3X when the distance is the distance L1 and the distance between the second coating gun 3Y and the workpiece 2 is the distance L2. Assuming that both of the detectable ranges are the same in the range S, the locus R is the same as the locus R shown in FIG. 7A. The second coating gun 3Y is displaced at a constant speed from the start position P to the end position Q.

Under such a displacement condition, the surface potential is measured in a manner as shown in FIG. 9 while the second coating gun 3Y is displaced with respect to the workpiece 2 by the second robot arm 4Y ( S303), determination based on the measured surface potential is performed (S304).
At this time, the distance between the second coating gun 3Y and the object to be coated 2 is set to a distance L2 that is smaller than the coating distance, and the surface potential is measured by bringing the coating gun 3 closer to the object to be coated 2. Thus, the surface potential is measured with higher accuracy.

  This determination is made based on whether or not the measured surface potential is equal to or lower than a predetermined set potential Vk as shown in FIG. 5, and if the measured surface potential value V3 is equal to or lower than the set potential Vk. Then, it is determined that the ground state of the article 2 is good, and the determination is repeated until the position of the second coating gun 3Y reaches the predetermined end position Q (S305).

Alternatively, if the value of the measured surface potential V3 exceeds the set potential Vk, it is determined that the ground state of the article 2 is abnormal and the measurement is terminated (S307). (S308). The content of the abnormality process here is, for example, a process for confirming the grounding state of the earth clip or the like on the workpiece 2 in which an abnormality is recognized.
When the abnormality process is completed, the determination that the state is abnormal is reset (S309).

Then, after the measurement of the surface potential is completed (S306) or after the abnormal state is reset (S309), the conveyor is operated to remove the workpiece 2 from the inspection position (S310).
As described above, the measurement of the surface potential by the second electrostatic coating apparatus 1Y is completed, and the ground state inspection using the two electrostatic coating apparatuses 1X and 1Y is completed.

That is, in the ground state inspection method according to the second embodiment of the present invention, the first electrostatic coating apparatus 1X and the first electrostatic coating apparatus 1X use the first and second electrostatic coating apparatuses 1X and 1Y. A high voltage is applied to the surface, and the potential on the surface of the article to be coated 2 is measured by the second electrostatic coating apparatus 1Y.
With such a configuration, the waiting time after the charge is applied can be shortened, and the inspection time can be further shortened.

DESCRIPTION OF SYMBOLS 1 Electrostatic coating apparatus 1X 1st electrostatic coating apparatus 1Y 2nd electrostatic coating apparatus 2 To-be-coated object 3 Coating gun 3X 1st coating gun 3Y 2nd coating gun 4 Robot arm 4X 1st robot arm 4Y 2nd robot arm 9 High voltage generator 9X First high voltage generator 9Y Second term voltage generator

Claims (7)

A paint gun for spraying paint on the object,
A robot arm that displaceably supports the paint gun;
High voltage generation for adjusting a high voltage to be generated by generating a high voltage to be applied to the coating gun and detecting a discharge current generated when an electric field is formed between the coating gun and the object to be coated Equipment,
An electrostatic coating apparatus comprising:
With the paint gun,
In a state where the paint is not sprayed toward the object to be coated, an electrostatic field is formed from the coating gun toward the object to be coated, and the object is charged with electric charge.
By the high voltage generator,
In a state where a high voltage is not applied to the coating gun by the high voltage generator, a discharge current generated between the coating gun and the object to be coated is detected based on a charge charged on the object to be coated.
An electrostatic coating apparatus characterized by that. Comprising the first and second electrostatic coating devices,
Forming an electrostatic field from the coating gun of the first electrostatic coating apparatus toward the object to be coated, and charging the object to be charged;
By the high voltage generator of the second electrostatic coating device,
Detecting a discharge current generated between the coating gun of the second electrostatic coating apparatus and the object to be coated by the electric charge charged on the object to be coated;
The electrostatic coating apparatus according to claim 1. By the high voltage generator,
When a high voltage is not applied to the coating gun by the high-voltage generator, and when a discharge current generated between the coating gun and the object to be coated is detected by a charge charged on the object to be coated,
The distance between the coating gun and the object to be coated is smaller than the coating distance during electrostatic coating.
The electrostatic coating apparatus according to claim 1 or 2, wherein the apparatus is an electrostatic coating apparatus. When an electrostatic field is formed from the coating gun toward the object to be charged, and the object is charged with electric charge,
The displacement distance of the paint gun is made smaller than the displacement distance of the paint gun during electrostatic painting.
The electrostatic coating apparatus according to any one of claims 1 to 3, wherein the apparatus is an electrostatic coating apparatus. By the high voltage generator,
When a high voltage is not applied to the coating gun by the high-voltage generator, and when a discharge current generated between the coating gun and the object to be coated is detected by a charge charged on the object to be coated,
The displacement distance of the paint gun is made smaller than the displacement distance of the paint gun during electrostatic painting.
The electrostatic coating apparatus according to any one of claims 1 to 4, wherein the apparatus is an electrostatic coating apparatus. After applying a conductive primer to the object to be coated, a high voltage is applied to the object to be coated, and a potential at the surface of the object to be coated is measured to check the ground state of the object to be coated. An inspection method,
Using an electrostatic coating device, while applying a high voltage to the object to be coated, and measuring the potential on the surface of the object to be coated,
A ground state inspection method characterized by the above. Using the first and second electrostatic coating apparatuses,
While applying a high voltage to the object to be coated by the first electrostatic coating apparatus,
The second electrostatic coating apparatus measures the potential at the surface of the object to be coated.
The ground state inspection method according to claim 6.

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