JP6998909B2 - Electrostatic coating device, monitoring device and electrostatic coating method - Google Patents

Description

The present invention relates to an electrostatic coating device, a monitoring device, and an electrostatic coating method in which fine particles are charged and applied to an object to be coated.

In electrostatic coating, which is a type of electrostatic coating, the target object to be coated is grounded, and charged paint particles ejected from a coating gun having a high potential difference adhere to the object to be coated to be coated. .. In electrostatic coating, application is started from the grounded part, and the object to be coated is coated while expanding the grounded area through the formed coating film. Here, if the object to be coated is not surely grounded, electric charges are accumulated in the object to be coated as the charged paint fine particles adhere. As a result, the relative potential difference with respect to the coating gun becomes small, and the coating particles do not properly adhere to the object to be coated, resulting in poor quality such as coating unevenness and insufficient film thickness. Furthermore, since the electric charge is accumulated in the object to be coated, a spark may occur between the object and the jigs arranged around the object, or an electric discharge may occur when the operator removes the object to be coated, resulting in a disaster. There is also a danger of electric charge. Therefore, it is inspected before painting whether the ground contact condition of the object to be coated is good.

Conventionally, as a method of inspecting the ground contact state of an object to be coated, before painting, the object to be coated is charged with a coating gun used for electrostatic coating, and then the coating gun is brought close to the object to be coated to be coated. A technique for determining the quality of a grounded state by measuring a discharge current generated from a coating material to a coating gun is disclosed (see, for example, Patent Document 1). In this method, if it is determined that the ground contact condition of the object to be coated is good before painting, it is considered that the ground contact condition of the object to be coated is good thereafter, and electrostatic coating is performed.

Japanese Unexamined Patent Publication No. 2012-71224

Even if there is a gap between the jig on which the object to be coated is installed and the object to be coated and the grounding condition is not good, the gap is narrow and the charge accumulated in the object to be coated due to partial discharge is eliminated. Then, electrostatic coating can be performed normally. However, the above-mentioned technique only determines whether or not the grounding state is good. Therefore, even if the ground contact state is not good, it is not possible to determine the state in which electrostatic coating is possible, and the control range of the object to be coated is narrow.

Further, in order to measure the discharge current, it is necessary to perform a measurement-dedicated operation of moving the coating gun to a specified place with respect to the object to be coated, so that the work efficiency is poor.

Furthermore, even if it is possible to judge whether the grounding condition is good or bad before painting, the same method cannot be used during painting, and whether the grounding condition is good or not suitable for electrostatic coating during painting. It cannot be determined whether or not.

It is an object of the present invention to provide an electrostatic coating device and an electrostatic coating method which have a wide control standard for installation of an object to be coated and can prevent the occurrence of quality defects and accidents by monitoring during coating.

The present invention provides means for solving the above problems.
A support part that supports the object to be coated and
A coating portion having a higher potential than the object to be coated and ejecting charged paint fine particles to the object to be coated.
With a grounded terminal that is in contact with or near the object to be coated and is grounded.
A partial discharge detection unit that detects a partial discharge between the object to be coated and the ground terminal,
A first current measuring unit that measures the current flowing from the object to be coated to the ground, or a second current measuring unit that detects the current flowing from the coating unit to the ground.
Based on the detection result of the partial discharge detection unit and the measurement result of the first current measurement unit or the second current measurement unit, it is determined whether or not the object to be coated is in a state where electrostatic coating is possible. Judgment unit and
Provided is an electrostatic coating device.

With this configuration, even if it is determined from the measurement results of the first current measuring unit or the second current measuring unit that electrostatic coating cannot be performed, whether or not electrostatic coating can be performed based on the detection results of the partial discharge detection unit. You can accurately judge whether or not.

It is preferable that the determination unit continuously monitors whether or not the object to be coated is in a state where it can be electrostatically applied.

With this configuration, it is possible to grasp the conductive state between the object to be coated and the ground terminal, which may occur due to vibration or the like during electrostatic coating.

Whether the partial discharge is generated based on at least one of the amplitude, the generation interval, and the number of occurrences per unit time of the partial discharge pulse signal detected by the partial discharge within the set time. You just have to judge whether or not.

The partial discharge detection unit may be any of a high frequency CT sensor, a TEV sensor, an acoustic sensor, and an electromagnetic wave receiving antenna.

The object to be coated is made of a non-conductive material and is made of a non-conductive material.
It is preferable that the object to be coated is provided with a conductive piece that is attached to the object to be coated in a state where the conductive primer is not applied and the ground terminal is arranged in contact with or close to the ground terminal.

With this configuration, even if the object to be coated is a non-conductive material, it is possible to form a ground contact state and perform electrostatic coating.

The fine particles are paints
The coating portion may be a coating gun that sprays the paint.

The present invention provides means for solving the above problems.
A support part that supports the object to be coated and
With a grounded terminal that is in contact with or near the object to be coated and is grounded.
A partial discharge detection unit that detects a partial discharge between the object to be coated and the ground terminal,
A first current measuring unit that measures the current flowing from the object to be coated to the ground, and
Based on the detection result of the partial discharge detection unit and the measurement result of the first current measurement unit, a determination unit for determining whether or not the object to be coated is in a state where electrostatic coating is possible, and a determination unit.
Provide a monitoring device equipped with.

A second current measuring unit for measuring the current flowing from the coating unit to the ground is further provided.
In the determination unit, in addition to the detection result of the partial discharge detection unit and the measurement result of the first current measurement unit, the object to be coated is static based on the measurement result of the second current measurement unit. It is preferable to determine whether or not the electric coating is possible.

With this configuration, it is possible to accurately determine whether or not electrostatic coating can be performed with even higher accuracy.

The present invention provides means for solving the above problems.
Supports the object to be coated,
A ground terminal connected to the ground wire is placed in contact with the object to be coated or in the vicinity of the object to be coated.
A coating portion having a higher potential than the object to be coated is brought closer to the object to be coated.
A partial discharge between the object to be coated and the coated portion is detected.
The grounding current flowing from the coating part to the ground is detected.
Provided is an electrostatic coating method for determining whether or not the object to be coated is in a state where electrostatic coating is possible based on the partial discharge and the grounding current.

The current of the object to be coated flowing from the object to be coated to the portion to be coated is further measured, and the object to be coated can be electrostatically coated based on the current of the object to be coated in addition to the partial discharge and the grounding current. It is preferable to determine whether or not it is.

When the object to be coated is a non-conductive material, a conductive piece is attached to the object to be coated.
The ground terminal is placed in contact with or in the vicinity of the conductive piece.
It is preferable to start the coating from the vicinity of the conductive piece.

According to the present invention, it is possible to determine whether or not the static elimination is suitable for electrostatic coating even if the grounding is not good, so that the control standard for installing the object to be coated becomes wider than in the conventional case by checking before coating. In addition, since it can be monitored even during painting, it is possible to prevent the occurrence of quality defects such as uneven coating and insufficient film thickness, and to prevent accidents such as sparks on jigs and electric shock of workers.

It is a schematic diagram of the electrostatic coating apparatus which concerns on this embodiment. It is a flowchart which shows the content of the electrostatic coating process which is executed by the control apparatus shown in FIG.

Hereinafter, embodiments according to the present invention will be described with reference to the accompanying drawings. It should be noted that the following description is merely an example and is not intended to limit the present invention, its application, or its use. In addition, the drawings are schematic, and the ratio of each dimension is different from the actual one.

(First Embodiment)
FIG. 1 shows an electrostatic coating device according to the first embodiment. This electrostatic coating device includes a support unit 1, a coating unit 2, a ground terminal 3, a first current measuring unit 4, a second current measuring unit 5, a partial discharge detecting unit 6, and a determination unit 7.

The support portion 1 is provided with a jig 10 at the tip of a support shaft 9 protruding from the base 8. A non-conductor 18 is provided in the middle portion of the support shaft 9. The jig 10 supports the object to be coated 11 (here, a resin bumper). The support portion 1, that is, the object to be coated 11 supported by the jig 10 is conveyed by the conveyor 12. A conductive piece 13 is attached to the object to be coated 11. When the object to be coated 11 is placed on the support portion 1, the conductive piece 13 is configured to come into contact with the ground terminal 3. When the object to be coated 11 is made of a conductive material, the conductive piece 13 becomes unnecessary.

A coating gun 14 that sprays paint onto the object to be coated 11 is used in the coating unit 2. The coating gun 14 includes a bell cup 15 at the tip portion thereof. The bell cup 15 is rotated by an air motor or the like (not shown). The fluid paint is spread on the inner surface of the bell cup 15 and atomized by the rotation of the bell cup 15 to become coated fine particles. Further, the coating unit 2 is provided with a high voltage generator 16 (cascade). The high voltage generator 16 applies a negative electrostatic high voltage to the coating portion 2 to charge the coating fine particles obtained by the bell cup 15 on the negative electrode side. Further, a high voltage controller 17 is electrically connected to the high voltage generator 16. The high voltage controller 17 sets the voltage output from the high voltage generator 16 to an arbitrary value (−90 to −30 kV). As described above, according to the coating unit 2, an electric field is formed between the bell cup 15 to which a high voltage is applied and the grounded object 11, and the paint fine particles obtained by the bell cup 15 are charged. The Coulomb force acts toward the object to be coated 11. Therefore, the coated fine particles are efficiently coated on the object to be coated 11. The coating unit 2 can change the position of the bell cup 15 with respect to the object to be coated 11 by a robot arm (not shown).

The ground terminal 3 is arranged so as to come into contact with the object to be coated 11 in a state where the object to be coated 11 is placed at an appropriate position with respect to the support portion 1. A ground wire l extends from the ground terminal 3 through the support portion 1. As a result, when the object to be coated 11 is placed on the support portion 1, it is in a state of being grounded from the ground terminal 3 via the ground wire l.

The first current measuring unit 4 is provided in the middle of the grounding wire l extending from the grounding terminal 3 in contact with the object to be coated 11. The current value measured by the first current measuring unit 4 is input to the determination unit 7.

The second current measuring unit 5 is provided between the high voltage generator 16 and the high voltage controller 17. The second current measuring unit 5 measures the current flowing from the coating unit 2 to the ground. The measurement result of the second current measuring unit 5 is input to the determination unit 7. The second current measuring unit 5 can be housed in the high voltage controller 17.

The partial discharge detection unit 6 is arranged in the vicinity of the contact portion between the object to be coated 11 and the ground terminal 3 or in the ground wire l. The partial discharge detection unit 6 detects the partial discharge generated between the object to be coated 11 and the ground terminal 3 when the contact is not properly performed. The detection result (detection value) in the partial discharge detection unit 6 is input to the determination unit 7. The partial discharge detection unit 6 can be configured by a high frequency CT sensor, a TEV (Transient Earth Voltage) sensor, an acoustic sensor, an electromagnetic wave receiving antenna, or the like (FIG. 1 shows an example using a high frequency CT sensor).

The determination unit 7 determines whether or not the object to be coated 11 is in a state where it can be electrostatically coated based on the detection signals input from the first current measurement unit 4, the second current measurement unit 5, and the partial discharge detection unit 6. Is determined. The monitoring device according to the present invention is configured by the first current measuring unit 4, the second current measuring unit 5, the partial discharge detection unit 6, and the determination unit 7.

Next, the operation of the electrostatic coating device having the above configuration will be described with reference to the flowchart of FIG.

The object to be coated 11 is attached to the jig 10 protruding from the base 8. At this time, the conductive piece 13 previously attached to the object to be coated 11 comes into contact with the ground terminal 3. However, when the object to be coated 11 is attached to the jig 10, the object to be coated 11 cannot always be arranged accurately, and the conductive piece 13 and the ground terminal 3 may be in a non-contact state.

Therefore, first, the first measured current value i1 measured by the first current measuring unit 4 is read (step S1). Then, it is determined whether or not the read first measured current value i1 is larger than the preset first set current value Is1 (step S2). If the first measured current value i1 is larger than the first set current value Is1, it is determined that the object to be coated 11 is grounded from the conductive piece 13 via the ground terminal 3, and the electrostatic coating process by the coating unit 2 is performed. Is started (step S3).

By the way, the first measured current value i1 is affected by the leakage current, the air discharge, and the like on the coating machine side. Therefore, even when the first measured current value i1 is equal to or less than the first set current value Is1, there is a possibility that the object to be coated 11 can be electrostatically coated. Therefore, if the first measured current value i1 is equal to or less than the first set current value Is1 (step S2: NO), the second measured current value i2 measured by the second current measuring unit 5 is read (step S4). Then, it is determined whether or not the read second measured current value i2 is larger than the second set current value Is2 (step S5). If the second measured current value i2 is larger than the second set current value Is2, it is determined that the contact state of the ground terminal 3 with the conductive piece 13 of the object to be coated 11 is appropriate, and the electrostatic coating process by the coating unit 2 is performed. Start (step S3).

On the other hand, if the second measured current value i2 is equal to or less than the second set current value Is2 (step S5: NO), the detection signal detected by the partial discharge detection unit 6 is read (step S6). Examples of the detection signal index include the maximum value, the average value, the generation interval, and the average value of the generation frequency of the pulse waveform (partial discharge pulse signal) measured by the partial discharge. When the maximum value is used as an index, the value having the largest amplitude of the pulse waveform in the preset time width is used. When the average value is used as an index, the value obtained by averaging the amplitudes of the pulse waveforms with a preset time width (set time) is used. When the generation interval is used as an index, the time (generation interval) from when the pulse waveform exceeds the preset threshold value to when it falls below the threshold value and then exceeds the threshold value again is measured and measured within the preset time. Use the value obtained by averaging the occurrence intervals. When the average value of the generation frequency is used as an index, the value obtained by averaging the generation cycles within a preset time is used with the reciprocal of the generation interval as the generation cycle.

Then, it is determined whether or not the detection value x in the partial discharge detection unit 6 exceeds the preset reference set value S (step S7). If the detected value x exceeds the reference set value S (if the detected value x is the occurrence interval, it is less than the reference set value S), even if the first current measuring unit 4 and the second current measuring unit 5 are used. Even if the measured currents v1 and v2 are equal to or less than the set current values Vs1 and Vs2, respectively, it is determined that the object to be coated 11 can be electrostatically coated, and electrostatic coating is started (step S3).

On the other hand, if the detected value x is equal to or less than the reference set value S (when the detected value x is the occurrence interval, the reference set value S or more) (step S7: NO), the object to be coated 11 is not in a state where electrostatic coating is possible. Is determined, and the user is notified (step S8). The user reattaches the object to be coated 11 to the jig 10 to improve the contact state of the ground terminal 3 with the conductive piece 13 of the object to be coated 11, and then returns to the step S1 again to perform the same process. Just execute.

Further, even during electrostatic coating, detection by the first current measuring unit 4, the second current measuring unit 5, and the partial discharge detecting unit 6 is continued. This is because the contact state between the conductive piece 13 and the ground terminal 3 may change even after the electrostatic coating is started. For example, the case where the object to be coated 11 is displaced from the jig 10 due to vibration caused by driving the conveyor 12 or the coating portion 2 is applicable. Further, if the conductive piece 13 is electrostatically coated, the conductive state with the ground terminal 3 may be deteriorated.

If it is determined that the object to be coated 11 cannot be electrostatically coated during electrostatic coating, the application is interrupted and then the user is notified. The user confirms the object to be coated 11 and determines whether the coated state is good or bad. If it is determined that the object to be coated 11 is a non-defective product, it is sent to the next step, and if it is determined to be a defective product, it is discarded.

As described above, according to the above-described embodiment, it is determined whether or not electrostatic coating can be performed by detecting the partial discharge. As a result, even if it is determined that electrostatic coating cannot be performed by the conventional method, it can be appropriately determined if electrostatic coating can actually be performed.

The present invention is not limited to the configuration described in the above embodiment, and various modifications can be made.

In the above embodiment, the first current measuring unit 4 and the second current measuring unit 5 are provided, but only one of them may be configured. In this case, it is preferable to use only the first current measuring unit 4.

In the above embodiment, although not particularly mentioned, a semiconductor may be used instead of the non-conductor 18 of the support shaft 9 of the support portion 1. The semiconductor prevents the object to be coated 11 and the jig 10 from being electrically floated and charged even if the second current measuring unit 5 has a grounding failure due to a failure. can do.

In the above embodiment, the partial discharge detection unit 6 for detecting a signal obtained from the partial discharge generated when there is a gap between the conductive piece 13 and the ground terminal 3, such as a high frequency CT sensor, has been described. It can also be detected from an image obtained by imaging the piece 13 and the ground terminal 3. That is, it may be possible to determine whether or not the object to be coated 11 can be electrostatically coated by imaging the partial discharge using a camera and analyzing the imaging result.

In the above embodiment, the case where the object to be coated 11 to be electrostatically coated is a resin bumper has been described, but examples of the object to be coated 11 include a rocker molding, a resin door, a resin fender, a resin hood, and the like. Can be mentioned.

In the above embodiment, the conductive piece 13 of the object to be coated 11 and the ground terminal 3 are composed of only one set, but two sets may be used. According to this, when the object to be coated 11 is placed on the jig 10, the probability that the object to be grounded 11 can be grounded increases. If the object to be coated 11 is grounded by conducting with only one of them, electrostatic coating can be normally performed.

1 ... Support part 2 ... Coating part 3 ... Ground terminal 4 ... 1st current measurement part 5 ... 2nd current measurement part 6 ... Partial discharge detection part 7 ... Judgment part 8 ... Base 9 ... Support shaft 10 ... Jig 11 ... Object to be coated 12 ... Conveyor 13 ... Conductive piece 14 ... Coating gun 15 ... Bell cup 16 ... High voltage generator 17 ... High voltage controller 18 ... Non-conductor

Claims (11)

A support part that supports the object to be coated and
A coating portion having a higher potential than the object to be coated and ejecting charged paint fine particles to the object to be coated.
With a grounded terminal that is in contact with or near the object to be coated and is grounded.
A partial discharge detection unit that detects a partial discharge between the object to be coated and the ground terminal,
A first current measuring unit that measures the current flowing from the object to be coated to the ground, or a second current measuring unit that detects the current flowing from the coating unit to the ground.
Based on the measurement results of the first current measuring unit or the second current measuring unit, it is determined whether or not the object to be coated is in a state where electrostatic coating is possible, and it is not in a state where electrostatic coating is possible. Even in the case of determination, a determination unit for determining whether or not the object to be coated is in a state where electrostatic coating is possible based on the measurement result of the partial discharge detection unit .
Equipped with an electrostatic coating device. When the determination unit determines that electrostatic coating is not possible based on the measurement result of the first current measurement unit, the second current is prior to the determination based on the measurement result of the partial discharge detection unit. The electrostatic coating device according to claim 1, wherein it is determined whether or not the object to be coated is in a state where it can be electrostatically coated based on the measurement result in the measuring unit. Whether the partial discharge is generated based on at least one of the amplitude, the generation interval, and the number of occurrences per unit time of the partial discharge pulse signal detected by the partial discharge within the set time. The electrostatic coating device according to claim 1 or 2, which determines whether or not. The electrostatic coating device according to any one of claims 1 to 3, wherein the partial discharge detection unit is any one of a high frequency CT sensor, a TEV sensor, an acoustic sensor, and an electromagnetic wave receiving antenna. The object to be coated is made of a non-conductive material and is made of a non-conductive material.
The static electricity according to any one of claims 1 to 4, further comprising a conductive piece attached to the object to be coated in a state where the conductive primer is not applied and the ground terminal is arranged in contact with or close to each other. Electric coating device. The fine particles are paints
The electrostatic coating device according to any one of claims 1 to 5, wherein the coating portion is a coating gun that sprays the paint. A support part that supports the object to be coated and
A coating portion having a higher potential than the object to be coated and ejecting charged paint fine particles to the object to be coated.
With a grounded terminal that is in contact with or near the object to be coated and is grounded.
A partial discharge detection unit that detects a partial discharge between the object to be coated and the ground terminal,
A first current measuring unit that measures the current flowing from the object to be coated to the ground, and
Based on the measurement result of the first current measuring unit, it is determined whether or not the object to be coated is in a state where electrostatic coating is possible, and even when it is determined that the object to be coated is not in a state where electrostatic coating is possible. Further, a determination unit for determining whether or not the object to be coated is in a state where electrostatic coating is possible based on the measurement result of the partial discharge detection unit, and a determination unit.
A monitoring device. A second current measuring unit for measuring the current flowing from the coating unit to the ground is further provided.
In the determination unit, in addition to the detection result of the partial discharge detection unit and the measurement result of the first current measurement unit, the object to be coated is static based on the measurement result of the second current measurement unit. The monitoring device according to claim 7, wherein it is determined whether or not the electric current can be applied. Supports the object to be coated,
A ground terminal connected to the ground wire is placed in contact with the object to be coated or in the vicinity of the object to be coated.
A coating portion having a higher potential than the object to be coated is brought closer to the object to be coated.
A partial discharge between the object to be coated and the ground terminal is detected.
Measure the grounding current flowing from the coating part to the ground,
Based on the ground current, it is determined whether or not the object to be coated is in a state where electrostatic coating is possible, and even when it is determined that the object is not in a state where electrostatic coating is possible, it is further based on the partial discharge. An electrostatic coating method for determining whether or not the object to be coated is in a state where it can be electrostatically coated. When the current of the object to be coated flowing from the object to be coated to the coating portion is further measured and it is determined that electrostatic coating is not possible based on the grounding current, the subject is subjected to the determination based on the partial discharge. The electrostatic coating method according to claim 9, wherein it is determined whether or not the object to be coated is in a state where electrostatic coating is possible based on the coating current. When the object to be coated is a non-conductive material, a conductive piece is attached to the object to be coated.
The ground terminal is placed in contact with or in the vicinity of the conductive piece.
The electrostatic coating method according to claim 9 or 10, wherein the coating is started from the vicinity of the conductive piece.

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