JP4649805B2 - Coating object inspection device and coating object inspection method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a coating object inspection apparatus and a coating object inspection method used when a coating object such as a car body part of an automobile is painted.
[0002]
[Prior art]
When a component made of resin such as polypropylene is applied by electrostatic coating, a conductive primer is applied to the component, and then a top coat is applied on the component by electrostatic coating. In addition to drying the conductive primer before overcoating, it may be overcoated in a wet state without passing through a drying step.
[0003]
By the way, electrostatic coating uses a coating gun to which a high voltage is applied to spray paint particles on the object to be coated in a charged state, thereby electrostatically adsorbing the paint particles to the object to be coated. For this reason, when the object to be painted is not electrically grounded, painting cannot be performed correctly.
[0004]
Therefore, conventionally, in order to check that the object to be painted is grounded before painting, as shown in FIG. 7, while holding the part from the back side with a conductive jig, the electrode is brought into contact with the surface of the part, The conduction was checked by applying a DC voltage of several kV between the electrode and the jig.
[0005]
[Problems to be solved by the invention]
However, in recent years, instead of applying a conductive primer, there has been proposed an electrostatic coating method that uses a material (conductive resin) that is made conductive by adding a conductor such as carbon to a resin (for example, Japanese Patent Laid-Open No. Hei. No. 8-500520). This conductive resin has the property that the volume resistivity is high when a low voltage is applied, and the volume resistivity is low due to the movement of electrons between carbon molecules when a high voltage is applied, and static electricity is generated by a corona discharge of about −90 kV. Electropainting is performed. For this reason, in order to apply the above-described conventional method to a conductive resin component, it is necessary to simultaneously check the volume resistivity and grounding of the resin at a high voltage such that the conductive resin can be conductive. If the jig that holds the part is not properly grounded, or if the volume resistivity or time constant of the part itself is greater than or equal to the specified value, sparks may occur if the coating machine approaches the surface to be painted during painting. There will be no paint. Further, for example, the change in volume resistivity in the conductive noryl resin is as shown in FIG. 8, but in the above conventional measurement method, the measurement result may differ by two digits or more due to the influence of the dirt on the surface of the component. It is difficult to measure well. For this reason, there is a demand for means capable of simultaneously checking volume resistivity and grounding when using this type of conductive resin.
[0006]
Therefore, an object of the present invention is to provide a novel means capable of detecting whether the electrical state of the object to be coated is suitable for electrostatic coating.
[0007]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided a voltage applying means for applying a voltage to the object to be coated, a detecting means for detecting the potential of the object to be coated to which the voltage has been applied, and the electrical of the object to be painted based on the detected potential. Determination means for determining a state, the determination means based on a comparison of the detected potential, a predetermined first reference value, and a predetermined second reference value higher than the first reference value. A coating object inspection apparatus characterized by determining a neutralization state of the painting object. In the first aspect of the present invention, since the static elimination state is determined using two different reference values, the static elimination status can be determined in detail.
[0008]
2nd this invention is a coating object test | inspection apparatus of 1st this invention, Comprising: The said detection means detects the electric potential of the said coating object in the transient state after a voltage is applied by the voltage supply means. This is a paint object inspection device.
In the second aspect of the present invention, the potential in the transient state of the coating target to which a voltage is applied is detected, and the electrical state of the coating target is determined based on the detected potential.
[0009]
The potential of the coating target in the transient state varies depending on whether the jig holding the component is properly grounded or whether the volume resistivity / surface resistivity of the component itself is greater than or equal to a predetermined value. take. Therefore, in the second aspect of the present invention, the electrical state of the object to be coated can be correctly detected based on the potential in the transient state.
[0012]
The third of the present invention, prior Symbol judging means, than the reference value of the potential is the first of said paint object of predetermined time after the application stops the voltage to the coating object by said voltage applying means It is a coating object inspection apparatus characterized by performing the determination which permits the electrostatic coating with respect to the said coating object when it is low.
The fourth of the present invention, prior Symbol judging means, the detected potential and the first reference value and ground conditions and conductivity of the coating object of the coating target based on a comparison between the second reference value It is a coating object inspection apparatus characterized by determining property .
[0013]
In the fourth aspect of the present invention, based on the detected potential as compared with the first reference value and second reference value, the determining the ground state or conductive coating object, with a simple structure, paint It is possible to specify a case where the grounding state or conductivity of the target is insufficient.
[0016]
The fifth of the present invention, prior Symbol detection means is a coating target inspection apparatus characterized by detecting the potential of said coated object in a state of the painted object and the non-contact.
[0017]
In the fifth aspect of the present invention, in addition to the effects of the first to fourth aspects of the present invention, the detection means detects the potential of the coating target in a non-contact state with the coating target. The occurrence of sparks can be prevented.
[0018]
The sixth aspect of the present invention applies a voltage to the object to be coated, detects the potential of the object to be coated to which the voltage is applied, and is higher than the detected potential, the predetermined first reference value, and the first reference value. A method for inspecting a coating object , wherein the neutralization state of the painting object is determined based on a comparison with a predetermined second reference value .
The 7 th aspect of the present invention, the front Symbol detection is an inspection method for coating the object, characterized by detecting the potential of said coated object in a transient state after a voltage is applied. In the seventh aspect of the present invention, the same effect as in the second aspect of the present invention can be obtained.
[0020]
The present invention The eighth pre SL determination, electrostatic coating for the coating object when the potential of the coating object of a predetermined time after the application of voltage is stopped is lower than the first reference value This is a method for inspecting an object to be painted, characterized in that a determination is made to allow the coating.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the drawings. In FIG. 1, the coating object inspection apparatus 1 according to the embodiment includes a non-contact surface potential sensor 3, a discharge probe 5, and a main body 7.
[0022]
The non-contact surface potential sensor 3 detects the surface potential of the object to be coated in a non-contact manner from a remote position. For example, a vibration type chopper using a sound wave is incorporated and the electric field received by the detection electrode is periodically changed. It is preferable to use an AC voltage conversion type.
[0023]
The main body 7 includes a high voltage generator 9 including a large-capacitance capacitor, a switch 11 for turning on and off the output of the high voltage generator 9, and a first timer 13 that is activated by detecting the time when the switch 11 is turned on. A second timer 14 that is activated when the first timer 13 times out, a surface potential measuring device 15 that calculates a surface potential based on a signal from the non-contact surface potential sensor 3, a reference value setting device 17, and a surface potential and a reference The determination unit 19 is configured to determine the ground contact based on the magnitude relationship with the value. The output of the determiner 19 is connected to a line controller 20 configured as a computer system. The line controller 20 carries in, stops, and carries out the body according to the output from the determiner 19 and other conditions and operation inputs. To control. The surface potential measuring device 15 is grounded, and thereby an absolute potential can be measured.
[0024]
The main body 7 is configured as a microprocessor centered on a CPU, and includes a ROM that stores processing programs, a RAM that temporarily stores data, and an input / output port, and includes a first timer 13 and a second timer. Each function of the timer 14, the surface potential measuring device 15, the reference value setting device 17 and the determination device 19 is executed as described later.
[0025]
The object to be inspected according to the present embodiment is illustrated by taking the resin panel 30 used for the tire housing portion of the vehicle body as an example. Any part can be applied as long as it is a skin coating. The resin panel 30 is made of a conductive noryl resin obtained by adding carbon to a resin to impart conductivity, and electrostatic coating is performed by corona discharge of about −90 kV. The resin panel 30 is fixed to a vehicle body body 32 made of a steel plate by a conductive bolt 36 via a conductive coating jig 34. The coating jig 34 may not be used. The vehicle body 32 is mounted on a carriage 40 as shown in FIG. 2, and is conveyed by a floor conveyor. The vehicle body 32 is always grounded via the carriage 40 and the floor conveyor. The non-contact surface potential sensor 3 and the discharge probe 5 described above are disposed along the conveyance path of the carriage 40, and a limit switch 42 for detecting the stop of the carriage 40 is provided. The operation of the carriage 40 is controlled by the line controller 20 described above.
[0026]
The reference value th1 set in the reference value setting unit 17 is set as a value for determining whether or not the resin panel 30, the coating jig 34 holding the resin panel 30, and the vehicle body 32 are properly grounded. In the form, it is used as a discriminating value whether or not electrostatic coating can be permitted. The reference value th1 can be set to an arbitrary value by an operator's operation, and can be set to, for example, 500V. The determination device 19 compares the surface potential calculated by the surface potential measuring device 15 with the reference value th1 set by the reference value setting device 17, and if the surface potential is lower than the reference value th1, it outputs a permission signal. In addition, when it exceeds, a non-permission signal is output to the line controller 20.
[0027]
The inspection by the coating object inspection apparatus 1 of the present embodiment is performed immediately after the molding process of the resin panel 30 and immediately before each of the intermediate coating process and the top coating process performed by electrostatic coating. In this inspection, the processing performed in the coating object inspection apparatus 1 and the line controller 20 is as follows.
[0028]
In FIG. 3, first, based on the signal from the limit switch 42, it is determined whether or not the vehicle body 32 has arrived at the inspection position (S10). A control signal is output (S20). Next, application of voltage by the high voltage generator 9 is started, and at the same time, the first timer 13 is started (S30). The first timer 13 is set to count a time T1 sufficient for the potential of the resin panel 30 to rise to a value suitable for inspection.
[0029]
On the condition that the counting by the first timer 13 is completed, that is, T1 seconds have elapsed (S40), the voltage application is stopped and the counting by the second timer 14 is started (S50).
[0030]
Further, the measurement of the surface potential is started (S60). The surface potential is measured by the non-contact surface potential sensor 3 and the surface potential measuring device 15 for T2 seconds set by the second timer 14 (S70).
[0031]
When T2 seconds have elapsed, the reference value th1 set by the reference value setting unit 17 and the surface potential calculated by the surface potential measuring unit 15 are compared in the determination unit 19 (S80). As a result of this comparison, when the surface potential is lower than the reference value th1, an affirmative determination is made that electrostatic coating may be performed, a predetermined end process is performed for the surface potential measurement (S90), and the vehicle body departure process As a result, a start instruction control signal for the carriage 40 is output (S140). As a result, the operation of the carriage 40 is resumed, and the vehicle body 32 is put into the electrostatic coating process.
[0032]
On the other hand, if the surface potential exceeds the reference value th1 as a result of comparison in step S80, a negative determination is made that electrostatic coating should not be performed, and a predetermined end process is performed for the surface potential measurement (S100). ) A predetermined conveyor stop process is performed by the line controller 20 (S110). During the conveyor stop process, a predetermined abnormality flag in the storage area of the line controller 20 is set. Then, when an abnormal treatment is performed manually and a predetermined resumption input is made (S120), the abnormality flag is reset (S130), and a start instruction control signal for the carriage 40 is output as the vehicle body departure processing ( S140). As a result, the operation of the carriage 40 is resumed, and the vehicle body 32 is put into the electrostatic coating process.
[0033]
As described above, in the present embodiment, the output of the high voltage generator 9 as the inspection voltage source is switched by the switch 11, and the transition period after T2 seconds have elapsed from time b (see FIG. 4) at the time of this switching. The potential of the coating object at time c is detected, and whether or not electrostatic coating is possible is determined based on a comparison between the detected potential and the reference value th1.
[0034]
Here, in the present embodiment, the resin panel 30 has a predetermined electrical characteristic as to the potential of the object to be coated in a transient state after time b, which is the time of switching of the high voltage generator 9 (off operation of the switch 11). Thus, different values are taken depending on whether or not the resin panel 30 is correctly molded, and whether or not the resin panel 30, the coating jig 34 holding the resin panel 30, and the vehicle body 32 are properly grounded. That is, the potential of the object to be coated is correctly formed so that the resin panel 30 has predetermined electrical characteristics, and when the resin panel 30, the coating jig 34, and the vehicle body 32 are correctly grounded, Although it attenuates quickly like V1 in FIG. 4, if the resin panel 30 does not have predetermined electrical characteristics, or if the resin panel 30, the painting jig 34 or the vehicle body 32 is not properly grounded, V2 The high value changes like Therefore, in this embodiment, by comparing the surface potential of the resin panel 30 with the reference value th1, it is possible to correctly detect whether the object to be coated is grounded or whether the resin panel 30 has predetermined electrical characteristics.
[0035]
Next, a second embodiment will be described. The electrical characteristics of parts to be painted, especially volume resistivity, surface resistivity, and time constant, vary depending on the molding conditions. In particular, conductivity is imparted by adding a conductor such as carbon to the resin. However, when the volume resistivity, surface resistivity, or time constant is greater than the specified value, electrostatic coating cannot be performed satisfactorily. When a high voltage is applied, there is a risk of causing sparks, which makes it impossible to paint. Therefore, in the second embodiment, in addition to determining whether or not the resin panel 30 to be painted is properly grounded, the conductivity of the resin panel 30 itself to be painted is also determined.
[0036]
In the second embodiment, the reference value setting unit 17 sets a plurality of different reference values. That is, in the reference value setting unit 17, as shown in FIG. 5, the reference value th1 for determining whether or not the resin panel 30 is properly grounded (the same value as that in the first embodiment). In addition, a reference value th2 for determining the conductivity of the resin panel 30 itself is set. These reference values th1 and th2 can be set to arbitrary values by the operation of the operator. For example, the reference value th1 can be set to 500V, and the reference value th2 can be set to 1 kV. The determiner 19 compares the reference value th2 set by the reference value setter 17 with the surface potential calculated by the surface potential measuring device 15, and the surface potential exceeds the reference value th1, but the reference value When it is less than th2 (when the surface potential is V3 in FIG. 5), it is a material failure signal, and when the surface potential is above the reference value th2 (when the surface potential is V2 in FIG. 5), it is grounded. A defect signal is output to the line controller 20. The line controller 20 is provided with output means for outputting such information as character information or voice information to the operator when a material failure signal / grounding failure signal is received. In addition, since the other mechanical structure of 2nd Embodiment is the same as that of the said 1st Embodiment, the detailed description is abbreviate | omitted.
[0037]
Processing in the second embodiment will be described. In FIG. 6, the processes of steps S210 to S310 are the same as the processes of steps S10 to S70 in the first embodiment.
[0038]
When the conveyor stop process is performed in step S310, the surface potential previously calculated by the surface potential measuring device 15 (S260) is compared with the reference value th2 (S320). As a result of this comparison, when the surface potential is lower than the reference value th2, an affirmative determination is made that the cause of the abnormality is defective conductivity in the resin panel 30 (deterioration of charge removal due to insufficient volume resistivity or time constant). A predetermined material defect signal is output to the line controller 20 (S330). On the other hand, when the surface potential exceeds the reference value th2, a predetermined ground failure signal is output to the line controller 20 assuming that the cause of the abnormality is a ground failure of the resin panel 30 (S340). In the line controller 20, character information and voice information respectively corresponding to these material failure signals or ground failure signals are output to the operator by the output means.
[0039]
Then, when an abnormal treatment is performed manually and a predetermined resumption input is made (S350), the abnormality flag is reset (S360), and a start instruction control signal for the carriage 40 is output as the vehicle body departure processing ( S370). As a result, the operation of the carriage 40 is resumed, and the vehicle body 32 is put into the electrostatic coating process.
[0040]
As described above, in the second embodiment, the potential of the object to be coated and the predetermined reference value th2 in the time point after the time point b, which is the time point of the switching of the high voltage generator 9 (off operation of the switch 11), particularly in the transient state. Since the conductivity of the resin panel 30 itself is determined on the basis of the comparison, the case where the conductivity of the resin panel 30 is insufficient can be specified.
[0041]
In the second embodiment, both the determination whether the resin panel 30 to be painted is properly grounded (S280) and the determination of the conductivity of the resin panel 30 itself (S320) are performed. A configuration in which only the latter determination is performed may be employed.
[0042]
Further, in each of the above embodiments, the potential of the object to be coated at time c, which is a time point after T2 seconds from the time point b when switching by the switch 11, is detected and compared with the reference value th1 or the reference value th2. However, it may be configured to detect grounding failure or material failure and output this when the surface potential falls below the reference value while detecting the surface potential continuously or discretely. Has the advantage of being able to quickly determine and output a grounding failure or material failure.
[0043]
In each of the above embodiments, the absolute potential of the resin panel 30 that is the object to be coated is detected. Instead of such a configuration, the relative potential of the object to be coated with respect to the predetermined reference potential held by the detecting means is determined in advance. The relative potential of the object to be coated with respect to the reference potential held by the detecting means may be measured, and the absolute potential or ground potential of the reference potential may be added to this and compared with a predetermined reference value. .
[0044]
Further, in each of the above embodiments, the switching time of the high voltage generator 9 is set as the OFF operation time (time b) of the switch 11, and the potential of the coating object at the time after the OFF operation is set to the reference value th1 or Although it was set as the structure compared with the reference value th2, not only the discharge characteristic of the resin panel 30 which is the object to be coated but also the charge characteristic differs depending on whether or not there is a grounding defect or a material defect. That is, the increase in the surface potential when a high voltage is applied should be steep in the case of grounding failure or material failure (volume resistivity / surface resistivity or excessive time constant). Therefore, instead of or in addition to the configuration of each of the above embodiments, a change in surface potential after the time point when the switch 11 is turned on (time a) is detected, and the surface after a predetermined time is detected. When the potential is higher than a predetermined reference value, this may be determined as a grounding failure and / or a material failure.
[0045]
In addition to the configuration in which the potential of the coating target is compared with a reference value as in each of the above embodiments, the amount of change per unit time or the differential value in the transient state of the potential of the coating target is compared with a predetermined reference value. Such a configuration also belongs to the category of the present invention. Moreover, although the said embodiment demonstrated the example which applies this invention about the coating object which consists of conductive Noryl resin, this invention is what applied the conductive primer to other kinds of conductive resin, non-conductive resin, etc. It is possible to apply to a coating object made of other various materials.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a schematic configuration of an embodiment of the present invention.
FIG. 2 is a perspective view showing an arrangement of each member in a painting target inspection process.
FIG. 3 is a flowchart showing processing in the first embodiment.
FIG. 4 is a timing chart showing the relationship between voltage application, surface potential and reference value in the first embodiment.
FIG. 5 is a timing chart showing the relationship between voltage application, surface potential and reference value in the second embodiment.
FIG. 6 is an explanatory view showing a conventional process for inspecting a coating object.
FIG. 7 is a graph showing an example of electrical characteristics of a conductive noryl resin.
FIG. 8 is a graph showing a change in volume resistivity in a conductive noryl resin.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Coating object inspection apparatus, 3 Non-contact surface potential sensor, 5 Discharge probe, 9 High voltage generator, 11 Switch, 13 1st timer, 14 2nd timer, 15 Surface potential measuring device, 17 Reference value setting device, 19 Judgment 20 line controller, 30 resin panel, 32 car body, 34 painting jig, th1, th2 standard values.

Claims (8)

Voltage application means for applying a voltage to the object to be coated;
Detecting means for detecting a potential of the coating object to which a voltage is applied;
Determination means for determining an electrical state of the object to be coated based on the detected potential ,
The determination means determines the neutralization state of the coating object based on a comparison of the detected potential, a predetermined first reference value, and a predetermined second reference value higher than the first reference value. A coating object inspection device characterized by The coating object inspection apparatus according to claim 1,
The coating object inspection apparatus, wherein the detection means detects a potential of the coating object in a transient state after a voltage is applied by the voltage supply means. The coating object inspection device according to claim 1 or 2,
The determination means applies to the painting object when the potential of the painting object after a predetermined time after the application of the voltage to the painting object by the voltage application means is lower than the first reference value. A coating object inspection apparatus characterized by performing a determination of permitting electrostatic coating . The coating object inspection device according to any one of claims 1 to 3 ,
The coating means characterized in that the determination means determines the grounding state of the coating target and the conductivity of the coating target based on a comparison between the detected potential and the first reference value and the second reference value. Target inspection device. The coating object inspection apparatus according to any one of claims 1 to 4 ,
The coating object inspection apparatus , wherein the detection means detects the potential of the coating object in a non-contact state with the coating object. A voltage is applied to the object to be coated, the potential of the object to be coated to which the voltage is applied is detected, the detected potential, a predetermined first reference value, and a predetermined second reference value higher than the first reference value. A method for inspecting a coating object, characterized in that the neutralization state of the painting object is determined based on a comparison with the method. An inspection method for a coating object according to claim 6,
The method for inspecting a coating object, wherein the detection includes detecting a potential of the object to be coated in a transient state after a voltage is applied. An inspection method for a coating object according to claim 7,
The determination is performed by determining whether to permit electrostatic coating on the coating target when the potential of the coating target after a predetermined time after the application of the voltage is lower than the first reference value. A characteristic inspection method for painting objects.

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