JP2015073948A - Rotary atomization electrostatic coating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotary atomization electrostatic coating device which can control a shape of a spray pattern while suppressing a bounce of paint particles.SOLUTION: A coating device 1 comprises a device main body 11, a rotary atomization head 121, a needle-shape electrostatic electrode 13, a voltage generator 14 and a control part 15. The rotary atomization head 121 is rotatably mounted to a front end part of the device main body 11, and sprays paint to an object to be painted. The needle-shape electrostatic electrode 13 is arranged at an external peripheral side of the device main body 11. The voltage generator 14 applies a voltage to the needle-shape electrostatic electrode 13. The control part 15 controls a shape of a spray pattern formed of paint which is sprayed from the rotary atomization head 121 by variably controlling the voltage.

Description

  The present invention relates to a rotary atomizing electrostatic coating apparatus.

  Electrostatic coating devices are widely used for painting automobile bodies and the like. The electrostatic coating apparatus forms an electrostatic field between both electrodes with the object to be coated as an anode and the coating apparatus as a cathode, and adsorbs the atomized paint charged on the negative side to the object by electrostatic force.

  The rotary atomizing electrostatic coating device supplies paint to a rotating atomizing head (bell head) that rotates at high speed, and the direction of the object to be coated with respect to the paint sprayed in the rotating direction by the centrifugal force of the rotating atomizing head Spray the shaping air. Thereby, the spray pattern which consists of paint particles is formed.

  In the rotary atomizing electrostatic coating apparatus of Patent Document 1, a wider electrostatic field than the electrostatic field formed by the apparatus itself is formed by providing needle-shaped electrostatic electrodes facing outward on the outer peripheral surface of the apparatus. The As a result, the paint particles that bounce off the object to be coated and are floating can be carried to the object to be coated.

JP 2006-82064 A

  Conventionally, the size of the spray pattern has been adjusted by adjusting the air pressure (jet power) of the shaping air. That is, when the air pressure is lowered, the force to carry the paint particles sprayed from the rotary atomizing head to the object to be coated is weakened, and the diameter of the spray pattern is increased. On the other hand, when the air pressure is increased, the force to carry the paint particles sprayed from the rotary atomizing head to the object to be coated is increased, and the diameter of the spray pattern is decreased. However, when the air pressure is high, the paint particles that have struck the object to be coated rebound and fly to the rotary atomizing electrostatic coating apparatus without being applied to the object to be coated. For this reason, there existed a problem that a rotary atomization electrostatic coating apparatus will become dirty.

  The present invention has been made to solve such a problem, and provides a rotary atomizing electrostatic coating apparatus capable of controlling the shape of a spray pattern while suppressing the rebound of paint particles. It is aimed.

  A rotary atomizing electrostatic coating apparatus according to an aspect of the present invention includes an apparatus main body, a rotary atomizing head that is rotatably provided at a front end portion of the apparatus main body, and sprays paint on an object to be coated. The first electrode provided on the outer peripheral side of the first electrode, first voltage applying means for applying a first voltage to the first electrode, and variably controlling the first voltage, thereby rotating the atomization. Control means for controlling the shape of the spray pattern formed by the paint sprayed from the head. Thereby, the shape of the spray pattern can be controlled without changing the air pressure of the shaping air. Therefore, it is possible to control the shape of the spray pattern while suppressing the rebound of the paint particles.

  And a second voltage applying means for applying a second voltage to the rotary atomizing head, wherein the control means individually controls the first voltage and the second voltage. Variable control may be performed.

  The first electrode may include a plurality of needle-like electrodes, and may be arranged on a circle around the rotary atomizing head.

  A second circle arranged on the circumference of a circle including a plurality of needle-like electrodes, the circle being centered on the rotary atomizing head and having a diameter different from the circle on which the first electrodes are arranged; And a third voltage applying means for applying a third voltage to the second electrode, and the control means comprises the first voltage and the third voltage, respectively. The shape of the spray pattern may be controlled by performing variable control individually.

  A rotary atomizing electrostatic coating apparatus according to an aspect of the present invention includes an apparatus main body, a rotary atomizing head that is rotatably provided at a front end portion of the apparatus main body, and sprays paint on an object to be coated. An electrode to which a voltage is applied, and a first distance from the rotation axis of the rotary atomizing head to an end of the electrode is from the rotary axis to the rotary atomizing head. It is 3.8 times or more of the second distance to the end. Thereby, the period during which the sprayed paint particles are subjected to the electrostatic force directed toward the rotation axis of the rotary atomizing head is lengthened. Therefore, the diameter of the spray pattern can be reduced without changing the air pressure of the shaping air. Therefore, it is possible to control the shape of the spray pattern while suppressing the rebound of the paint particles.

  Further, the apparatus may further include an air ejecting unit that ejects shaping air for spraying the paint onto the object to be coated, and an air pressure of the shaping air may be 0.01 MPa or less.

  The first distance may be not less than 3.8 times and not more than 5.2 times the second distance.

  According to the present invention, it is possible to provide a rotary atomizing electrostatic coating apparatus capable of controlling the shape of a spray pattern while suppressing the rebound of paint particles.

It is a figure which shows the structure of the coating device concerning Embodiment 1. FIG. 1 is a block diagram of a coating apparatus according to a first embodiment. FIG. 6 is a diagram for explaining the movement of paint particles according to the first embodiment. 1 is a front view of a coating apparatus according to a first embodiment. It is a table | surface which shows the relationship between the diameter of a needle-shaped electrostatic electrode, and a pattern diameter. It is a figure for demonstrating a pattern diameter. It is a front view of the coating device concerning a comparative example. It is a figure for demonstrating the motion of the paint particle concerning a comparative example. It is a figure for demonstrating the spray pattern concerning a comparative example. It is a table | surface which shows the relationship between SA pressure and coating efficiency. It is a table | surface which shows the relationship between SA pressure and the expansion rate of a spray pattern. It is a figure for demonstrating (phi) A and (phi) B of FIG. It is a figure for demonstrating the quantity of the overspray in a spray pattern with a wide base. It is a figure for demonstrating the quantity of the overspray in the spray pattern with a narrow base. It is a figure which shows the structure of the coating device concerning Embodiment 2. FIG. It is a figure which shows the structure of the coating device concerning Embodiment 3. FIG. It is a front view of the coating apparatus concerning Embodiment 3. FIG.

<Embodiment 1>
Embodiment 1 of the present invention will be described below with reference to the drawings. FIG. 1 shows an external view of a rotary atomizing electrostatic coating apparatus 1 (hereinafter simply referred to as a coating apparatus 1) according to the present embodiment. FIG. 2 shows a block diagram of the coating apparatus 1. The coating apparatus 1 includes an apparatus main body 11, a paint spraying unit 12, a needle-like electrostatic electrode 13, a voltage generator 14, and a control unit 15. The coating apparatus 1 performs coating by spraying a coating material on an object 90 to be coated.

  The object to be coated 90 is grounded and has a ground potential. On the other hand, a negative voltage is applied to the coating apparatus 1, and the coating particles are charged with a high voltage. Then, along the electric field generated by applying a voltage to the needle-like electrostatic electrode 13, the charged paint particles fly to the article 90 to be coated. Thereby, the paint particles are applied to the article 90.

  The apparatus main body 11 accommodates a paint spraying unit 12, a motor (not shown) that rotates the rotary atomizing head 121, and the like. A rotary atomizing head 121 and a shaping air ring 122 are located at the front side (object 90 side) end of the apparatus main body 11. The apparatus main body 11 is made of, for example, an insulating resin material.

  The paint spraying unit 12 is accommodated in the apparatus main body 11 and sprays the paint supplied from the outside onto the object to be coated 90. The paint spraying unit 12 includes a rotary atomizing head 121 (bell head) and a shaping air ring 122. The rotary atomizing head 121 is rotatably provided at the front end of the apparatus main body 11 and is driven to rotate by a motor accommodated in the apparatus main body 11. Then, by supplying the paint to the rotary atomizing head 121 in a rotationally driven state, the rotary atomizing head 121 sprays the paint by centrifugal force.

  The rotary atomizing head 121 is made of a conductive material such as metal. For this reason, a high voltage can be applied to the entire rotary atomizing head 121. By applying a voltage to the rotary atomizing head 121, the paint particles touching the surface of the rotary atomizing head 121 can be directly charged to a high voltage.

  The shaping air ring 122 (air ejection means) has a plurality of air ejection holes (not shown). Specifically, the shaping air ring 122 ejects shaping air in the direction of the object to be coated 90 (the arrow direction in FIG. 1) toward the paint sprayed from the rotary atomizing head 121. The ejected shaping air shapes the spray pattern of the paint particles sprayed from the rotary atomizing head 121. Note that the air pressure of the shaping air from the shaping air ring 122 can be adjusted.

  The shaping air ring 122 is made of a conductive material such as metal. For this reason, a high voltage can be applied to the entire shaping air ring 122. By applying a voltage to the shaping air ring 122, the paint particles that are blown off by the shaping air can be charged to a high voltage.

  The acicular electrostatic electrode 13 (first electrode) is an electrode provided on the outer peripheral side of the apparatus main body 11. The needle-like electrostatic electrode 13 is fixed to the shaping air ring 122 via an electrode support member 131 having conductivity. For this reason, a high voltage is applied to the acicular electrostatic electrode 13 through the shaping air ring 122 and the electrode support member 131. That is, in the present embodiment, the voltage applied to the shaping air ring 122 and the needle-like electrostatic electrode 13 is a common (same) voltage. By applying a high voltage to the needle-like electrostatic electrode 13, the electric field can be concentrated on the tip of the needle-like electrostatic electrode 13. Therefore, a strong electrostatic field E can be formed between the needle-shaped electrostatic electrode 13 and the object 90 to be coated. A plurality of broken lines included in the electrostatic field E indicate electric lines of force L of the electrostatic field E.

  The voltage generator 14 (first voltage applying means) is connected to the apparatus main body 11 via the high voltage cable 141. The voltage generator 14 is connected to the control unit 15 via the low voltage cable 142. The voltage generator 14 boosts the DC voltage input from the low voltage cable 142 to generate a DC power supply voltage (first voltage) of, for example, −30 kV to −150 kV. The generated power supply voltage is applied to the rotary atomizing head 121, the shaping air ring 122, and the needle-like electrostatic electrode 13 via the high-voltage cable 141.

  The control unit 15 variably controls the power supply voltage generated by the voltage generator 14. The control unit 15 is connected to the voltage generator 14 via the low voltage cable 142. For example, the control unit 15 outputs a DC voltage of about 20 V to the voltage generator 14 via the low voltage cable 142. The controller 15 variably controls the power supply voltage generated by the voltage generator 14 by changing the voltage input to the voltage generator 14. Thereby, the control unit 15 controls the shape of the spray pattern of the paint spraying unit 12.

  Then, with reference to FIG. 3, the motion of the paint particle in the coating device 1 concerning this Embodiment is demonstrated. FIG. 3 is a diagram showing the flight trajectory of the paint particles 20. First, when the paint supplied to the paint spraying unit 12 comes into contact with the rotary atomizing head 121, the paint is sprayed by the centrifugal force of the rotary atomizing head 121 that is rotationally driven. That is, the paint is sprayed radially about the rotation axis C of the rotary atomizing head 121.

  At this time, the paint is charged to a high voltage when it contacts the rotary atomizing head 121. Also, the paint sprayed from the rotary atomizing head 121 is sheared into fine particles (paint particles 20) by blowing shaping air. In addition, the coating particle 20 receives force in the discharge direction of the shaping air (the direction of the object to be coated 90) when the shaping air is blown.

  The paint particles 20 sprayed from the paint spraying part 12 are affected by the electrostatic field E formed by the acicular electrostatic electrode 13. Specifically, the electrostatic force F in the tangential direction of the electric force line L of the electrostatic field E is received. In the example shown in FIG. 3, the sprayed paint particles 20 are subjected to the electrostatic force F shown in FIG. More specifically, the paint particles 20 are subjected to a force including a force toward the rotation axis C of the rotary atomizing head 121 and a force toward the object 90 by the electrostatic force F. However, immediately after spraying, the centrifugal force (direction away from the rotation axis C) received by the paint particles 20 by the rotation of the rotary atomizing head 121 during spraying is greater than the electrostatic force F received by the paint particles 20 by the electric lines of force L. (The illustration is omitted.) Therefore, the paint particles 20 move in a direction away from the rotary atomizing head 121.

  However, even after spraying, the paint particles 20 always receive an electrostatic force F including a force directed toward the rotation axis C due to the influence of the electrostatic field E. For this reason, the force in the direction away from the rotation axis C generated by the centrifugal force is gradually canceled. Eventually, there is almost no force in the direction away from the rotation axis C, so that the paint particles 20 move along the lines of electric force and are applied to the object 90.

  At this time, since the paint particles 20 are negatively charged, the paint particles 20 can be regarded as the charge q. The charge q receives an electrostatic force F in the electrostatic field E. According to Coulomb's law, the electrostatic force F is expressed by F = qE. That is, when the electrostatic field E changes, the electrostatic force F also changes. By changing the power supply voltage applied from the voltage generator 14 to the needle-like electrostatic electrode 13, the electrostatic field E changes. That is, the electrostatic force F increases as the power supply voltage increases, and the electrostatic force F decreases as the power supply voltage decreases. Therefore, the control unit 15 controls the magnitude of the electrostatic force F received by the charge q (paint particles 20) by changing the power supply voltage generated by the voltage generator 14.

  When the electrostatic force F becomes smaller, the force in the direction of the object 90 becomes weaker. That is, the paint particles 20 are greatly affected by the centrifugal force generated by the rotary atomizing head 121. Therefore, the coating particle 20 spreads and the diameter of the spray pattern becomes large. On the other hand, when the electrostatic force F is increased, the force in the direction of the object 90 is increased. That is, the influence of centrifugal force by the rotary atomizing head 121 is reduced. Therefore, since the paint particles 20 do not spread and go toward the object 90, the diameter of the spray pattern is reduced.

  As described above, according to the configuration of the coating apparatus 1 according to the present embodiment, the control unit 15 changes the voltage supplied to the voltage generator 14 to change the needle-like electrostatic electrode 13 from the voltage generator 14. The voltage applied to is variably controlled. As a result, the electrostatic force F received from the electrostatic field E by the paint particles 20 having the charge q changes. As a result, the magnitude of the force in the direction of the object 90 changes. As a result, the shape of the spray pattern changes. Therefore, the control unit 15 can control the shape of the spray pattern without changing the air pressure of the shaping air.

  That is, the coating apparatus 1 adjusts the voltage applied to the needle-like electrostatic electrode 13 instead of adjusting the air pressure of the shaping air in order to control the shape of the spray pattern. Thereby, the magnitude | size of a spray pattern is controllable, without raising the air pressure of shaping air. Therefore, it is possible to reduce the amount of paint particles that rebound from the object 90 due to the influence of high air pressure.

  The control unit 15 variably controls the voltage applied from the voltage generator 14 to the needle electrostatic electrode 13 by changing the voltage supplied to the voltage generator 14 during spraying of the paint. Thereby, the shape of a spray pattern can be changed following fluidly the change of the shape of a coating site | part or a to-be-coated object. For this reason, it is possible to perform painting suitable for the part to be painted and the shape of the object to be coated, so that the coating quality and painting efficiency can be improved.

<Configuration of needle-like electrostatic electrode 13>
Here, the shape of the acicular electrostatic electrode 13 according to the present embodiment will be described in detail. The configuration of the rotary atomizing head 121 and the needle-like electrostatic electrode 13 according to this embodiment is shown in FIG. FIG. 4 is a front view of the coating apparatus 1 as viewed from the object 90 side. FIG. 5 shows the relationship between the diameter of the needle-like electrostatic electrode 13 and the diameter of the spray pattern. FIG. 5 is a table showing the diameter of the spray pattern when the diameter of the needle-like electrostatic electrode 13 is changed. In FIG. 5, the air pressure (SA (shaping air) pressure) is fixed at 0.01 MPa. Moreover, all the measurement results shown in FIG. 5 are measurement results when the diameter of the rotary atomizing head 121 is 77 mm. In the following description, the value of the pattern diameter means the width of the pattern at a height that is ½ of the maximum film thickness of the spray pattern (see FIG. 6).

  As shown in FIG. 4, the needle-like electrostatic electrode 13 is arranged on the outer circumference side of the apparatus main body 11 and on the circumference of a circle centering on the rotation axis C of the rotary atomizing head 121. Specifically, the needle-like electrostatic electrode 13 is fixed to the electrode support members 131 arranged radially from the shaping air ring 122. The coating apparatus 1 according to the present embodiment includes eight acicular electrostatic electrodes 13. The eight acicular electrostatic electrodes 13 are arranged symmetrically with respect to the rotation axis C when viewed from the front of the coating apparatus 1 (in plan view). The number of needle-like electrostatic electrodes 13 is not limited to eight, but is preferably arranged point-symmetrically with respect to the rotation axis C. As a result, uniform electrostatic fields E are generated vertically and horizontally, so that the shape of the spray pattern is stabilized.

  The diameter of the needle-like electrostatic electrode 13 according to the present embodiment is 300 mm, and the diameter of the rotary atomizing head 121 is 77 mm. That is, the diameter of the acicular electrostatic electrode 13 is about 3.8 times the diameter of the rotary atomizing head 121. In other words, the distance from the rotation axis C to the end of the needle-like electrostatic electrode 13 (first distance) is 3 (the second distance) from the rotation axis C to the end of the rotary atomizing head 121. About 8 times.

  The diameter of the needle-like electrostatic electrode 13 may be 400 mm. In this case, since the diameter of the needle-shaped electrostatic electrode 13 is 400 mm and the diameter of the rotary atomizing head 121 is 77 mm, the diameter of the needle-shaped electrostatic electrode 13 is 5.2 times the diameter of the rotary atomizing head 121. Degree. In other words, the distance (first distance) from the rotation axis C to the end of the needle-like electrostatic electrode 13 is 5 (the second distance) from the rotation axis C to the end of the rotary atomizing head 121. About 2 times.

  On the other hand, the structure of the rotary atomization head 121 and the acicular electrostatic electrode 93 concerning a comparative example is shown in FIG. The diameter of the needle-shaped electrostatic electrode 93 according to the comparative example is 168 mm, and the diameter of the rotary atomizing head 121 is 77 mm. That is, the diameter of the needle-like electrostatic electrode 93 is about 2.2 times the diameter of the rotary atomizing head 121. In other words, the distance from the rotation axis C to the end of the needle-like electrostatic electrode 93 is about 2.2 times the distance from the rotation axis C to the end of the rotary atomizing head 121.

  In the above description, the end portion of the needle-like electrostatic electrode is more specifically the tip portion of the needle-like electrostatic electrode, which is a portion where the electrostatic field E is formed in response to voltage application. is there. Moreover, the edge part of the rotary atomization head 121 is an outer periphery of the rotary atomization head 121, and the coating material supplied from the apparatus main body 11 is separated (released) from the rotary atomization head 121 into the air. It is.

  Next, the pattern diameter of the spray pattern of the coating apparatus 1 according to the present embodiment and the coating apparatus 9 according to the comparative example will be described. Note that the pattern diameter targeted by the coating apparatus 1 according to the present embodiment and the coating apparatus 9 according to the comparative example (both are coating apparatuses having a diameter of the rotary atomizing head 121 of 77 mm) is about 400 mm to 450 mm. .

  As shown in FIG. 5, the coating apparatus 1 according to the present embodiment has a pattern diameter of 400 mm when the diameter of the needle-like electrostatic electrode 13 is 300 mm in a state where the SA pressure is 0.01 Mpa. Moreover, when the diameter of the acicular electrostatic electrode 13 is 400 mm, the pattern diameter is 440 mm. Therefore, in any case, it is within the range of the target pattern diameter (400 mm to 450 mm).

  On the other hand, the coating apparatus 9 according to the comparative example has a pattern diameter of 500 mm when the diameter of the needle-like electrostatic electrode 93 is 168 mm when the SA pressure is 0.01 MPa. For this reason, the pattern diameter of the coating apparatus 9 according to the comparative example is larger than the target pattern diameter. This is because the diameter of the needle-like electrostatic electrode 93 is small as shown in FIG. Specifically, the distance from the end of the needle-like electrostatic electrode 93 to the end of the rotary atomizing head 121 is short. Thereby, the paint particles 20 that have jumped out from the end of the rotary atomizing head 121 immediately jump out of the end of the needle-like electrostatic electrode 93. For this reason, the period of receiving the electrostatic force F directed to the rotation axis direction of the rotary atomizing head 121 after the paint particles 20 jump out from the end of the rotary atomizing head 121 is shorter than that of the present embodiment (see FIG. 3). As a result, the paint particles 20 receive an electrostatic force F in a direction away from the rotation axis of the rotary atomizing head 121 immediately after being released from the rotary atomizing head 121. As a result, the pattern diameter increases.

  In the coating apparatus 9 of the comparative example, it is conceivable to increase the SA pressure and control the pattern diameter to be small so that the pattern diameter is within the target pattern diameter range (see FIG. 9). That is, this is a method in which the force of the paint particles 20 in the direction of the object 90 is increased, and the paint particles 20 are applied to the object 90 before spreading. However, when the SA pressure is increased, the amount of rebound of the paint particles 20 increases and the coating efficiency is lowered.

  Specifically, FIG. 10 shows the relationship between SA pressure and paint application efficiency (TE). In addition, the measurement result shown in FIG. 10 is a numerical value at the time of using the coating apparatus 9 concerning a comparative example. As shown in the table of FIG. 10, the coating efficiency at the SA pressure of 0.01 MPa is 99%, which is the highest value. And as the SA pressure is increased, the coating efficiency decreases. That is, as the SA pressure is increased, the amount of rebound of the paint particles 20 increases. That is, in the configuration of the coating apparatus of the comparative example, by increasing the SA pressure, the pattern diameter can be within the target pattern diameter range, but the coating efficiency is lowered.

  On the other hand, according to the structure of the coating apparatus 1 concerning this Embodiment, the diameter of the acicular electrostatic electrode 13 is 3.8 times or more of the diameter of the rotary atomizing head 121. FIG. That is, the distance from the rotation axis C to the end of the needle-like electrostatic electrode 13 is 3.8 times or more the distance from the rotation axis C to the end of the rotary atomizing head 121. Thereby, the distance from the edge part of the rotary atomization head 121 to the edge part of the acicular electrostatic electrode 13 becomes long compared with a comparative example. Therefore, the period when the coating particle 20 jumps out from the end of the rotary atomizing head 121 and receives the electrostatic force F directed in the rotation axis direction of the rotary atomizing head 121 is longer than that of the coating apparatus according to the comparative example (FIG. 3). reference). As a result, the coating particle 20 jumping out from the rotary atomizing head 121 is less spread than the comparative example. Therefore, the diameter of the spray pattern can be reduced without increasing the SA pressure. That is, the shape of the spray pattern can be controlled while suppressing the splashing of the paint particles.

  As described above, one of the points of the present invention is that the end of the needle-like electrostatic electrode 13 (electrostatic field E is generated from the end of the rotary atomizing head 121 (the part where the paint is separated from the coating apparatus 1). It is necessary to take a sufficient distance to the part to be made. Specifically, in the comparative example, the distance from the rotation axis C to the end of the needle-like electrostatic electrode is about 2.2 times the distance from the rotation axis C to the end of the rotary atomizing head 121. On the other hand, in this embodiment, it is 3.8 times or more.

  However, as shown in FIG. 4, when the diameter of the needle-shaped electrostatic electrode is increased from 168 mm to 300 mm, the pattern diameter tends to decrease. On the other hand, when the diameter of the needle-shaped electrostatic electrode is increased from 300 mm to 400 mm, the pattern diameter tends to increase. For this reason, it is considered that if the diameter of the needle-like electrostatic electrode 13 is further increased, it exceeds the target pattern diameter range (400 mm to 450 mm). Further, if the diameter of the needle-shaped electrostatic electrode 13 is too large, the distance between the object (wall, floor, ceiling, etc.) existing around the object 90 and the needle-shaped electrostatic electrode 13 may be reduced. In this case, an electrostatic field is generated from the acicular electrostatic electrode 13 to these objects. As a result, electric leakage or the like occurs, resulting in abnormal voltage of the needle-like electrostatic electrode 13.

  For this reason, the upper limit of the acicular electrostatic electrode 13 is preferably about 400 mm. In other words, the diameter of the needle-shaped electrostatic electrode 13 is preferably 5.2 times or less than the diameter of the rotary atomizing head 121. With such a configuration, as described above, the pattern diameter is also 440 mm, which is within the range of the target pattern diameter. Moreover, since the needle-like electrostatic electrode 13 having a diameter of 400 mm is sufficiently small compared to the size of the object 90 such as the body of an automobile, it is possible to avoid approaching the surrounding walls and the like. Therefore, the diameter of the needle-shaped electrostatic electrode 13 is preferably 3.8 times or more and 5.2 times or less of the diameter of the rotary atomizing head 121.

  Furthermore, the air pressure (SA pressure) is preferably 0.01 MPa. According to the configuration of the coating apparatus 1 according to the present embodiment, the pattern diameter can be reduced (the target pattern diameter can be realized) without increasing the air pressure. Therefore, by setting the coating efficiency to 0.01 Mpa, which is the highest in the table shown in FIG. 10, the coating efficiency can be improved while reducing the pattern diameter.

  Here, the merit of the narrow pattern diameter will be described. FIG. 11 shows the relationship between the SA pressure and the spread of the spray pattern base. In the table of FIG. 11, φA means the pattern diameter, φB means the width of the pattern at the height of 1/5 of the maximum film thickness, and the enlargement ratio means φB / φA (FIG. 11). 12). As shown in the table of FIG. 9, the higher the SA pressure, the easier the spread of the spray pattern. When the skirt spreads as described above, the overspray becomes large and the coating efficiency is deteriorated. In addition, the measurement result shown in FIG. 11 is a numerical value at the time of using the coating apparatus 9 concerning a comparative example.

  The amount of overspray according to the difference in the size of the skirt will be described with reference to FIGS. 13 and 14. FIG. 13 shows the amount of overspray of a spray pattern having a large skirt (large pattern diameter). Moreover, the amount of overspray of a spray pattern with a small base (pattern diameter is small) is shown in FIG. In any case, the first application (t1) is performed at a position centering on the end portion 901 of the object 90, and the application is shifted by a predetermined coating overlap pitch, the second application (t2), and the third application. The case where application | coating (t3) was performed is shown.

  As shown in FIG. 13, the amount of overspray of the spray pattern having a large base (the pattern diameter is large) is an area B <b> 1 to B <b> 3 located outside the end portion 901 of the object 90 (the lower side in FIG. 13). Is the sum of On the other hand, as shown in FIG. 14, the amount of overspray of the spray pattern having a small skirt (small pattern diameter) is an area S <b> 1 located on the outer side (lower side in FIG. 14) of the end 901 of the object 90. ~ S3 total.

  In the first application (t1), half of the applied paint is not applied to the object 90 and overspray occurs. At this time, if the spray pattern has a large base and the spray pattern having a small base, the amount of overspray is the same if the discharge amount is the same.

  However, in the second application (t2) and the third application (t3), the spray pattern with a small skirt has less overspray than the spray pattern with a large skirt. Therefore, overspray can be reduced when the pattern diameter is smaller.

<Embodiment 2>
A second embodiment according to the present invention will be described. FIG. 15 shows the configuration of the coating apparatus 2 according to the present embodiment. In the coating apparatus 2, an electrode support member 131 that supports the needle-like electrostatic electrode 13 is formed of an insulating material. For this reason, the shaping air ring 122 and the acicular electrostatic electrode 13 are electrically insulated.

  The coating apparatus 2 includes two voltage generators 14a and 14b and two control units 15a and 15b. The voltage generator 14a (first voltage applying means) applies the voltage V1 (first voltage) to the needle-like electrostatic electrode 13 via the high voltage cable 141a. The voltage generator 14b (second voltage applying means) applies the voltage V2 (second voltage) to the rotary atomizing head 121 and the shaping air ring 122 via the high voltage cable 141b. That is, the voltage V1 applied to the needle-shaped electrostatic electrode 13 and the voltage V2 applied to the rotary atomizing head 121 and the shaping air ring 122 are different voltages.

  The controller 15a controls the voltage V1 by changing the voltage supplied to the voltage generator 14a via the low voltage cable 142a. The controller 15b controls the voltage V2 by changing the voltage supplied to the voltage generator 14b via the low voltage cable 142b. That is, the coating apparatus 2 can individually control the voltage V1 and the voltage V2. Other configurations are the same as those of the coating apparatus 1.

  As described above, according to the configuration of the coating apparatus 2 according to the present embodiment, the voltage V1 and the voltage V2 are connected to different power sources. For this reason, the voltage V1 applied to the needle-shaped electrostatic electrode 13 and the voltage V2 applied to the rotary atomizing head 121 and the shaping air ring 122 can be controlled separately. Thus, when a high voltage is applied to the needle-like electrostatic electrode 13 and only the electrostatic field E is desired to be strengthened, only the voltage generator 14a and the control unit 15a need to generate a high voltage. That is, the voltage generator 14b and the control unit 15b that apply a voltage to the rotary atomizing head 121 and the shaping air ring 122 can suppress the applied voltage. As a result, the load on the voltage generator 14b and the control unit 15b can be reduced.

<Embodiment 3>
A third embodiment according to the present invention will be described. FIG. 16 shows the configuration of the coating apparatus 3 according to this embodiment. Moreover, the front view of the coating device 3 is shown in FIG. The coating apparatus 3 includes a plurality of needle-like electrostatic electrodes 13a arranged on the circumference of a circle centered on the rotary atomizing head 121, and a circle having a diameter different from the circle on which the needle-like electrostatic electrodes 13a are arranged. 13c and 13d (second electrode) arranged on the circumference of the. The diameter of the circle in which the acicular electrostatic electrode 13a is arranged is φa. The diameter of the circle in which the needle-like electrostatic electrode 13c is arranged is φc. The diameter of the circle in which the acicular electrostatic electrode 13d is arranged is φd. That is, all the circles have different diameters. Each circle is centered on the rotation axis C of the rotary atomizing head 121.

  The coating apparatus 3 includes three voltage generators 14a, 14c, and 14d and three control units 15a, 15c, and 15d. The voltage generator 14a (first voltage applying means) applies the voltage V1 to the needle-like electrostatic electrode 13a via the high voltage cable 141a. The voltage generator 14c (third voltage applying means) applies the voltage V3 (third voltage) to the needle-like electrostatic electrode 13c via the high voltage cable 141c. The voltage generator 14d (third voltage applying means) applies the voltage V4 (third voltage) to the needle-like electrostatic electrode 13d via the high voltage cable 141d. That is, the voltages V1, V3, and V4 applied to the needle-like electrostatic electrodes 13a, 13c, and 13d are different voltages.

  The controller 15a controls the voltage V1 by changing the voltage supplied to the voltage generator 14a via the low voltage cable 142a. The control unit 15c controls the voltage V3 by changing the voltage supplied to the voltage generator 14c via the low voltage cable 142c. The control unit 15d controls the voltage V4 by changing the voltage supplied to the voltage generator 14d via the low voltage cable 142d. That is, the coating apparatus 3 can individually control the voltages V1, V3, and V4. Other configurations are the same as those of the coating apparatus 1.

  As described above, according to the configuration of the coating apparatus 3 according to the present embodiment, the applied voltages of the needle-like electrostatic electrodes 13a, 13c, and 13d arranged on a plurality of circumferences having different diameters are individually controlled. . And each acicular electrostatic electrode 13a, 13c, 13d forms the electrostatic field E separately. Thereby, the three electrostatic fields E are combined, and a complex electrostatic field E that cannot be formed only by the needle-like electrostatic electrode arranged on one circumference can be formed. Therefore, variations in the pattern of the electrostatic field E can be increased. That is, variations in the shape of the spray pattern can be increased.

  The present invention is not limited to the above-described embodiment, and can be appropriately changed and combined without departing from the spirit of the present invention. For example, the dimensions of the needle-like electrostatic electrode 13 and the rotary atomizing head 121 are not limited to the numerical values in the above-described embodiment. As described above, if the distance from the end portion of the rotary atomizing head 121 to the end portion of the needle-like electrostatic electrode 13 is sufficient, the diameter of the needle-like electrostatic electrode 13 is the rotary fog. The size is not particularly limited as long as it is 3.8 times or more the diameter of the chemical head 121.

1-3, 9 Coating device 11 Device main body 12 Paint spraying unit 13, 93 Needle-shaped electrostatic electrode 14 Voltage generator 15 Control unit 20 Paint particle 90 Object to be coated 121 Rotating atomizing head 122 Shaping air ring 131 Electrode support member 141 High voltage cable 142 Low voltage cable

Claims (7)

The device body;
A rotary atomizing head that is rotatably provided at the front end of the apparatus main body and sprays paint on an object to be coated;
A first electrode provided on the outer peripheral side of the device body;
First voltage applying means for applying a first voltage to the first electrode;
Control means for controlling the shape of the spray pattern formed by the paint sprayed from the rotary atomizing head by variably controlling the first voltage;
A rotary atomizing electrostatic coating device comprising: A second voltage applying means for applying a second voltage to the rotary atomizing head;
The rotary atomizing electrostatic coating apparatus according to claim 1, wherein the control unit variably controls the first voltage and the second voltage individually.   3. The rotary atomizing electrostatic coating apparatus according to claim 1, wherein the first electrode includes a plurality of needle-like electrodes and is arranged on a circumference of a circle centering on the rotary atomizing head. A second electrode including a plurality of needle-like electrodes and centered on the rotary atomizing head and arranged on the circumference of a circle having a diameter different from that of the circle on which the first electrode is arranged When,
A third voltage applying means for applying a third voltage to the second electrode;
The said control means controls the shape of the said spray pattern by carrying out the variable control of each of the said 1st voltage and the said 3rd voltage separately, respectively. Rotary atomizing electrostatic coating device. The device body;
A rotary atomizing head that is rotatably provided at the front end of the apparatus main body and sprays paint on an object to be coated;
An electrode provided on the outer peripheral side of the apparatus main body, to which a voltage is applied,
A rotary mist in which a first distance from the rotation axis of the rotary atomizing head to the end of the electrode is 3.8 times or more a second distance from the rotary axis to the end of the rotary atomizing head. Electrostatic coating equipment. An air ejection means for ejecting shaping air for spraying the paint onto the object to be coated;
The rotary atomizing electrostatic coating apparatus according to claim 5, wherein an air pressure of the shaping air is 0.01 Mpa or less.   The rotary atomizing electrostatic coating apparatus according to claim 5 or 6, wherein the first distance is not less than 3.8 times and not more than 5.2 times the second distance.

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