JP5684672B2 - Coating method and coating apparatus - Google Patents

Description

  The present invention relates to a coating method and a coating apparatus that perform electrostatic coating by spraying a liquid paint from a rotary atomizing head.

  2. Description of the Related Art A rotary atomizing coating device is known as a coating device for painting a car body and the like. The rotary atomizing coating apparatus rotates while applying a high voltage to the rotary atomizing head, and supplies a conductive paint (liquid paint) to the rotary atomizing head in this state. As a result, the liquid paint is charged and atomized, and sprayed from the leading edge of the rotary atomizing head to perform electrostatic coating.

  In relation to the rotary atomizing coating apparatus, the following Patent Document 1 discloses that the pattern deformation air jets are moved up and down or left and right in order to eliminate a decrease in coating efficiency and uneven coating thickness due to a donut-shaped coating pattern. It is disclosed that the coating pattern is deformed into an oval shape by the pattern deformation air, and the coating film thickness is made uniform.

JP 60-54754 A

  However, in the oval coating pattern, the upper and lower and left and right application areas are different, and the coating thickness is not the same when applied in the vertical direction and when applied in the left and right direction. For this reason, the restriction | limiting with respect to the motion (teaching) of the coating gun for uniformly repainting a coating pattern is large.

  In addition, as a method different from Patent Document 1, it is conceivable to eliminate the donut shape by ejecting the annular shaping air with an inclination angle in the direction of the rotation axis larger than usual, but in that case, There is a restriction on the robot operation due to the deterioration of the coating efficiency due to the decrease in the diameter of the coating pattern and the increase in the size of the air ring which is a member for ejecting the shaping air.

  The present invention has been made in consideration of such a problem, and without increasing the size of a member for ejecting shaping air while ensuring the freedom of movement of the paint gun when repainting the paint pattern. An object of the present invention is to provide a coating method and a coating apparatus capable of reducing a non-coating portion generated in the vicinity of the rotational axis of the rotary atomizing head and obtaining a coating film having a uniform film thickness.

In order to achieve the above object, the present invention provides a coating method for coating the workpiece by directing paint discharged from a rotating rotary atomizing head to the workpiece side with annular shaping air, wherein the shaping air As a first air, the predetermined portion is ejected at a relatively high wind speed, and in parallel with the ejection of the first air, the other portion of the shaping air is the second air and is relatively more relative to the first air. And the second air is attracted to the first air side to displace a part of the second air to the rotation axis side of the rotary atomizing head, and the rotation of the rotary atomizing head A substantially circular coating pattern having an axis as a center is formed , the second air is formed in an annular shape, and the first air is inward of the second air and is circumferential with respect to the second air Partial range It is formed only with characterized Rukoto.

  According to the coating method of the present invention configured as described above, the second air is rotated and atomized by drawing the second air having a relatively low wind speed toward the first air side having a relatively high wind speed. It can be displaced to the rotational axis side of the head. Thereby, the non-coating site | part which arises in the rotation axis line vicinity of a rotary atomization head can be reduced, maintaining the shape of a coating pattern in substantially circular shape. Therefore, it is possible to obtain a coating film having a uniform film thickness without enlarging the member for ejecting the shaping air while ensuring the degree of freedom of movement of the coating gun when coating the coating pattern.

Moreover , by forming the first air inward of the second air, the second air can be displaced more effectively toward the rotation axis side of the rotary atomizing head, and the coating film thickness can be made uniform.

  In the above-described coating method, the first air may be formed in a plurality of areas that are equidistant from each other in the circumferential direction around the rotation axis of the rotary atomizing head. By forming the first air at locations spaced apart at equal intervals in the circumferential direction, the second air can be displaced toward the first air in a balanced manner, effectively reducing the non-coated portion of the coating pattern. Further, the coating film thickness can be made more uniform.

Further, the coating apparatus of the present invention is a coating provided with a rotary atomizing head that discharges paint to a workpiece, and an air ejection mechanism that ejects annular shaping air toward the outer peripheral edge of the rotary atomizing head. The air ejection mechanism is provided on the upstream side of the first air ejection port and the second air ejection port for ejecting the shaping air, and the first air ejection port and the second air ejection port, A plurality of buffer chambers partitioned by a partition wall, the first air having a relatively high wind speed is ejected from the first air ejection port, and the first air is relatively ejected from the second air ejection port. The second air having a low wind speed is ejected, and the second air is attracted to the first air side, thereby displacing a part of the second air to the rotational axis side of the rotary atomizing head and the rotational atomization. A roughly circular coating centered on the rotational axis of the head Forming a pattern, said second air jets, provided the second air so as to form the annular, the first air jets, in the inside of the second air, relative to the second air only provided to form the first air for some range in the circumferential direction Te characterized Rukoto.

  According to the coating apparatus according to the present invention configured as described above, the second air is rotated and atomized by drawing the second air having a relatively low wind speed toward the first air side having a relatively high wind speed. It can be displaced to the rotational axis side of the head. Thereby, the non-coating site | part which arises in the rotation axis line vicinity of a rotary atomization head can be reduced, and the coating film of uniform film thickness can be obtained, maintaining the shape of a coating pattern in substantially circular shape.

Moreover , by ejecting the first air from the inside of the second air, the second air can be displaced more effectively toward the rotational axis side of the rotary atomizing head, and the coating film thickness can be made uniform.

  In the coating apparatus, the first air outlet may be provided so as to form the first air in a plurality of areas that are equidistant from each other in the circumferential direction around the rotation axis of the rotary atomizing head. . Since the second air can be displaced to the first air side in a well-balanced manner by ejecting the first air from locations spaced apart at equal intervals in the circumferential direction, the non-coated portion of the coating pattern can be effectively reduced. Further, the coating film thickness can be made more uniform.

  According to the coating method and the coating apparatus of the present invention, the rotary atomizing head is secured without increasing the size of the member for ejecting the shaping air while ensuring the freedom of movement of the coating gun when the coating pattern is applied repeatedly. The non-coating part produced in the vicinity of the rotation axis of the film can be reduced to obtain a coating film having a uniform film thickness.

It is a schematic block diagram of the coating device which concerns on a reference example . It is a perspective view which shows the back surface of the ring member of the coating device shown in FIG. FIG. 3A is a schematic diagram showing the air flow in the buffer chamber when there is no partition wall, and FIG. 3B is a schematic diagram showing the air flow in the buffer chamber when there is a partition wall. It is typical explanatory drawing which shows that 2nd air is drawn near to the 1st air side. FIG. 5A is a graph showing a change in film thickness along the radial direction in the coating pattern when the wind speed at each position in the circumferential direction in the shaping air is the same, and FIG. 5B is a graph showing a change in the circumferential direction in the shaping air. It is a graph which shows the film thickness change along the radial direction in a coating pattern at the time of providing a high wind speed area in a part (this invention). FIG. 6A is a rear view of the ring member according to the first modification, and FIG. 6B is a rear view of the ring member according to the second modification. It is a schematic diagram of a coating device according to implementation embodiments of the present invention. FIG. 8A is a cross-sectional view taken along line VIIIA-VIIIA in FIG. 7, and FIG. 8B is a schematic explanatory view showing that the second air is drawn toward the first air side.

  Hereinafter, preferred embodiments of the coating method and the coating apparatus according to the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a schematic configuration diagram of a coating apparatus 10 according to a reference example . As shown in FIG. 1, the coating apparatus 10 includes at least a coating gun 12 that constitutes the apparatus main body and an air supply system 14 that supplies air for shaping air 17 to the coating gun 12.

  The coating gun 12 includes a casing 16 (housing), an air motor 18 provided in the casing 16, a rotary shaft 20 having a hollow structure that rotates at high speed by the air motor 18, and a pipe member 22 inserted through a hollow portion of the rotary shaft 20. And a bell-shaped rotary atomizing head 24 provided at the tip of the rotary shaft 20, and an air jet mechanism 26 that jets the shaping air 17 toward the outer periphery of the tip of the rotary atomizing head 24.

  The air motor 18 is configured to be supplied with compressed air from a compressed air source (not shown) and to rotate the rotating shaft 20 at a high speed. The rotary shaft 20 is connected to a high voltage generator (not shown) that generates a high voltage. Accordingly, a negative high voltage is applied to the rotary atomizing head 24 via the rotary shaft 20. The rotating shaft 20 is a member formed in a hollow cylindrical shape, and a tube member 22 is disposed in the hollow portion.

  A paint supply path 28 for flowing paint and a cleaning liquid supply path 30 for flowing cleaning liquid are formed in the tube member 22. The distal end portion of the tube member 22 is a double tube, and a paint supply nozzle 32 that discharges the paint and a cleaning liquid supply nozzle 34 that discharges the cleaning liquid are formed concentrically.

  The rotary atomizing head 24 is fixed to the tip of the rotary shaft 20, and when the rotary shaft 20 rotates under the action of the air motor 18, the rotary atomizing head 24 rotates together with the rotary shaft 20. In the rotary atomizing head 24, a paint reservoir 36 for temporarily storing the paint supplied via the pipe member 22 is formed. The paint reservoir 36 is a circular space. The paint supply nozzle 32 faces the center of the paint reservoir 36.

  The rotary atomizing head 24 is composed of an inner member 38 fixed to the rotary shaft 20 and a bell cup 40 fixed to the outer peripheral portion of the inner member 38, and between the inner member 38 and the bell cup 40. A paint reservoir 36 is formed. The inner member 38 is formed with a recess 38 a into which the tip of the rotary shaft 20 is fitted, and an opening through which the tip of the tube member 22 is inserted is formed at the center of the front surface of the inner member 38.

  The bell cup 40 is formed in a circular cup shape spreading outward in the radial direction toward the front. A paint discharge creeping surface 42 is formed on the front face of the bell cup 40 to thin the paint supplied to the front face. The coating material discharge creeping surface 42 is inclined forwardly outward in the radial direction, and is a donut-shaped surface in a front view. The coating material from the coating material reservoir 36 is thinned by a centrifugal force generated by the rotation of the bell cup 40.

  The bell cup 40 is provided with a plurality of paint supply holes 44 for supplying paint to the paint discharge creeping surface 42 at equal intervals in the circumferential direction around the rotation axis a of the rotary atomizing head 24. Each paint supply hole 44 is inclined toward the front of the rotary atomizing head 24 so as to be away from the axis a of the rotary atomizing head 24, and one end (inner end) is opened at the paint reservoir 36 and the other end ( The outer end) is open at the front surface of the bell cup 40.

  The central portion on the back side of the bell cup 40 protrudes toward the inside (the pipe member 22 side) of the paint reservoir 36 and distributes the supplied paint and cleaning liquid to the outside in the radial direction.

  A plurality of grooves 46 are formed at equal intervals in the circumferential direction on the front outer peripheral edge of the bell cup 40 (that is, the outer peripheral edge of the paint discharge creeping surface 42). The grooves 46 are provided at equal intervals in the circumferential direction over the entire circumference of the outer peripheral edge of the coating material discharge creeping surface 42, and extend along the radial direction of the rotary atomizing head 24. The thin film paint that has flowed radially outward is subdivided. Thereby, from the outer peripheral end of the bell cup 40, the paint (liquid yarn) in the form of a fine thread is released.

  Between the casing 16 and the air motor 18, a plurality (three in the illustrated example) of ring-shaped flow path forming members 50, 52 and 54 are arranged. Hereinafter, the flow path forming members 50, 52, and 54 are referred to as “first flow path forming member 50”, “second flow path forming member 52”, and “third flow path forming member 54”, respectively. The first flow path forming member 50 is disposed outside the air motor 18, and an annular recess 50a is formed on the outer periphery thereof.

  The second flow path forming member 52 is disposed between the first flow path forming member 50 and the casing 16, and a plurality of flow paths 52a penetrating in the axial direction are formed at intervals in the circumferential direction. An annular space 51 is formed by the first flow path forming member 50, the second flow path forming member 52, and the casing 16. The third flow path forming member 54 is disposed between the casing 16 and the first flow path forming member 50 and in front of the first flow path forming member 50 and the second flow path forming member 52. In the third flow path forming member 54, a plurality of flow paths 54a communicating with the flow path 52a of the second flow path forming member 52 are formed at intervals in the circumferential direction.

  A ring member 27 constituting the air ejection mechanism 26 is fixed to the tip of the third flow path forming member 54 concentrically with the bell cup 40 so as to surround the bell cup 40 on the back side of the bell cup 40. The shaping air 17 is ejected from the rear of the outer peripheral edge of the bell cup 40 toward the outer peripheral edge.

  FIG. 2 is a perspective view of the ring member 27 as seen from the back side. As shown in FIGS. 1 and 2, a first arcuate recess 60 and a second arcuate recess 62 are formed on the back surface of the ring member 27. The first arcuate recess 60 and the second arcuate recess 62 are partitioned by partition walls 64a and 64b and have substantially the same volume. An arc-shaped first buffer chamber 64 is formed by the first arc-shaped recess 60 and the front surface of the third flow path forming member 54. An arc-shaped second buffer chamber 66 is formed by the second arc-shaped recess 62 and the front surface of the third flow path forming member 54.

  As shown in FIG. 1, the ring member 27 further communicates with a plurality of air supply holes 68 that communicate the first buffer chamber 64 and the front surface of the ring member 27, and the second buffer chamber 66 and the front surface of the ring member 27. A plurality of air supply holes 70 are formed. The air supply hole 68 has one end (rear end) opened at the first buffer chamber 64 and the other end (front end) opened as an air jet outlet 68a on the front surface. One end (rear end) of the air supply hole 70 is opened at the second buffer chamber 66, and the other end (front end) is opened at the front surface as an air outlet 70a.

  The air supply hole 68 and the air supply hole 70 are provided at equal intervals in the circumferential direction centering on the axis a, and are inclined to approach the axis a of the rotary atomizing head 24 toward the front. 40 is opened toward the outer peripheral edge. The air supply holes 68 and 70 are inclined at a predetermined angle (for example, 30 degrees to 50 degrees) with respect to the direction of the axis a in the circumferential direction around the axis a of the rotary atomizing head 24.

  Of the air supply holes 68 and 70, those arranged in the vicinity of the partition wall are referred to as “first air supply holes 71a” (see FIGS. 2 and 3B), and are located in the circumferential direction from the partition wall to the first air supply hole 71a. What is provided at a distant place (a place between the first air supply holes in the vicinity of both ends in each of the first buffer chamber 64 and the second buffer chamber 66) is referred to as a “second air supply hole 71b” (FIGS. 2 and 3B). See). Of the plurality of air jets 68a, 70a, the one corresponding to the first air supply hole 71a is referred to as “first air jet 73a” (see FIG. 3B) and corresponds to the second air supply hole 71b. Is referred to as "second air jet 73b" (see FIGS. 1 and 3B).

  In the coating gun 12 shown in FIG. 1, the ring space 51, the plurality of channels 52 a of the second channel forming member 52, and the plurality of channels 54 a of the third channel forming member 54 are connected to the ring from the air supply system 14. An air supply path 72 for supplying compressed air to the member 27 is configured.

  As shown in FIG. 1, the air supply system 14 includes an air source 80 and an air line 82 that guides compressed air from the air source 80 to the coating gun 12. The air source 80 is an air pump, for example, and sends out compressed air. The air line 82 supplies compressed air to the annular space 51. A flow meter 88 and an electropneumatic converter 86 are disposed on the air line 82. The air control unit 90 controls the electropneumatic converter 86 so that the flow rate of air supplied to the air supply path 72 becomes a predetermined flow rate using the flow rate value detected by the flow meter 88 as a feedback value.

  The compressed air supplied to the coating gun 12 by the air line 82 of the air supply system 14 diffuses in the circumferential direction in the annular space 51, and then passes through the flow path 52a and the flow path 54a in order, and then passes through the first buffer chamber 64 and the first buffer chamber 64. 2 is introduced into the buffer chamber 66. The compressed air is further ejected from the air ejection ports 68a and 70a through the air supply holes 68 and 70 in the first buffer chamber 64 and the second buffer chamber 66, respectively.

  In this case, the first air 17a ejected from the first air ejection port 73a, which is the outlet of the first air supply hole 71a disposed in the vicinity of the partition walls 64a and 64b, is a predetermined portion of the shaping air 17 in the circumferential direction. Is a relatively high wind speed air. On the other hand, the second air 17b ejected from the second air ejection port 73b which is the outlet of the second air supply hole 71b disposed in the circumferential direction away from the partition walls 64a and 64b than the first air supply hole 71a. Is air of relatively low wind speed that constitutes another part of the shaping air 17 in the circumferential direction. That is, the wind speed (flow velocity) of the first air 17a is higher than the wind speed (flow velocity) of the second air 17b. The reason why the first air 17a ejected from the first air ejection port 73a has a higher wind speed than the second air 17b ejected from the second air ejection port 73b will be described later.

The coating apparatus 10 according to the reference example is basically configured as described above, and the operation and effect thereof will be described below.

  When painting, the rotary shaft 20 is rotated at high speed by the air motor 18. Then, the paint is discharged from the paint supply nozzle 32 toward the paint reservoir 36 of the rotary atomizing head 24. As a result, the paint that has flowed into the paint reservoir 36 flows into the paint supply hole 44. In this case, the paint that has passed through the paint supply hole 44 flows out to the paint discharge creeping surface 42, where it is thinned and then subdivided by the groove 46 and jumps out from the outer peripheral end of the bell cup 40 as liquid yarn. The liquid yarn discharged from the outer peripheral end of the bell cup 40 is atomized as paint particles.

  At this time, since a high voltage is applied between the rotary atomizing head 24 and the work (object to be coated), the charged paint particles atomized by the rotary atomizing head 24 fly toward the work. Apply to work. The spray pattern of the paint at this time is shaped by the shaping air 17 (first air 17a and second air 17b) ejected from the air ejection port.

By the way, unlike the configuration of the reference example , as shown in FIG. 3A, in the case of the configuration without the partition wall (prior art), the compressed air introduced into the buffer chamber 1 flows into the air supply hole 3 almost uniformly. It is ejected from the ejection port 5. For this reason, the wind speed of the air 7 ejected from the air ejection port 5 is substantially uniform. On the other hand, in the case of the reference example in which the first buffer chamber 64 and the second buffer chamber 66 are partitioned by the partition walls 64a and 64b, the pressure introduced into the first buffer chamber 64 and the second buffer chamber 66 as shown in FIG. 3B. Part of the compressed air flows along the partition walls 64a and 64b due to the Coanda effect, and the compressed air flows into the first air supply holes 71a arranged in the vicinity of the partition walls 64a and 64b. Thereby, the wind speed of the 1st air 17a ejected from the 1st air ejection port 73a becomes faster than the wind speed of the 2nd air 17b ejected from the 2nd air ejection port 73b.

As a result, as shown in FIG. 4, a relatively high wind speed area (first air 17 a) is formed in a part of the shaping air 17 in the circumferential direction. Only the air ejected from the first air outlet 73a, which is the outlet of the first air supply hole 71a disposed in the vicinity of the partition walls 64a, 64b, becomes the first air 17a having a relatively high wind speed. The circumferential range (angle range) in which the 1 air 17a is formed is considerably smaller than the circumferential range in which the second air 17b is formed. Further, in the reference example in which the two partition walls 64a and 64b are provided at intervals of 180 degrees, the place where the first air 17a is formed is a place opposite to each other with respect to the axis a (a place where the phase is shifted by 180 degrees). It is.

  As described above, when the flow velocity of a part (first air 17a) of the shaping air 17 ejected in an annular shape is made faster than the flow velocity of the other part (second air 17b), the pressure of the first air 17a is changed to the second air 17b. Therefore, a part of the second air 17b is drawn toward the first air 17a, and a part of the second air 17b is displaced toward the axis a. That is, as indicated by arrows in FIG. 4, the first air having a relatively low pressure is provided by shortcutting the inner side of the original arc shape of the second air 17 b at each circumferential portion constituting the second air 17 b. The action of displacing to the 17a side occurs.

  As a result, the inner peripheral portion of the second air 17b is drawn to a position closer to the axis a side than the original formation region of the second air 17b. And as a result of the inner peripheral part of the 2nd air 17b being drawn near to the axis line a side, a coating material can be apply | coated also to the axis line a vicinity. Therefore, while maintaining the shape of the coating pattern in a substantially circular shape, the non-coated part generated in the vicinity of the axis of the rotary atomizing head 24 can be reduced to obtain a coating film with a uniform film thickness, which can be efficiently applied. Can do.

  5A and 5B are graphs showing changes in the film thickness in the radial direction of the coating pattern when coating is performed under the following coating conditions. FIG. 5A shows the same wind speed in shaping air regardless of the position in the circumferential direction. FIG. 5B shows a case where the high wind speed area is provided in a part of the circumferential direction of the shaping air (the present invention). 5A and 5B, the horizontal axis is a radial position centered on the axis a (position of “0”), and the vertical axis is the coating thickness. 5A and 5B show film thickness data when applied for 0.6 seconds with the position of the coating gun fixed (stationary).

(Painting conditions)
Number of revolutions (rpm): 35000
Paint discharge rate (cc / min): 290
Paint discharge time (sec): 0.6
Painting distance (mm): 250
Applied voltage (kV): -60
Air flow rate (NL / min): 350

  As shown in FIG. 5A, when the wind speed in the shaping air is the same regardless of the position in the circumferential direction, a portion having a considerably large film thickness is generated at a position a predetermined distance from position 0 (axis line a). Further, in this case, if a portion of more than half of the maximum film thickness is defined as a coating pattern, in the example of FIG. 5A, the film thickness of the central portion including position 0 is smaller than the film thickness of the surrounding coating pattern. In the vicinity of the axis a, a so-called “uncoated part” was generated. The “non-coated portion” does not mean a portion where no paint is applied, but means a portion where the film thickness is considerably smaller than the maximum film thickness.

  On the other hand, in the case of the present invention in which a high wind speed area is provided in a part of the circumferential direction in the shaping air, the film thickness at a relatively large film thickness generated at a predetermined distance from position 0 is the film at the same position in FIG. It became smaller than the thickness. Further, in this case, if a portion having a half or more of the maximum film thickness is defined as a coating pattern, in the example of FIG. 5B, the central portion including the position 0 is included in the coating pattern. There was no “landing site”.

As described above, according to the coating apparatus 10 and the coating method according to the reference example , the second air 17b having a relatively low wind speed is attracted to the side of the first air 17a having a relatively high wind speed. The air 17b can be displaced to the axis a side of the rotary atomizing head 24. Thereby, the non-coating site | part which arises in the axial line a vicinity of the rotary atomization head 24 can be reduced, maintaining the shape of a coating pattern substantially circular. Therefore, the coating film having a uniform film thickness is obtained without enlarging the member (ring member 27) for ejecting the shaping air 17 while ensuring the degree of freedom of movement of the coating gun 12 when the coating pattern is applied repeatedly. Can be obtained.

In the reference example, part of the shaping air 17 in the circumferential direction constitutes the first air 17a, the other part in the circumferential direction constitutes the second air 17b, and the first air 17a is the second air. Since the air 17b is ejected in a range smaller than the circumferential range of the air 17b, the second air 17b is effectively displaced toward the axis a of the rotary atomizing head 24 when the second air 17b is drawn toward the first air 17a. Can be made.

Furthermore, in the case of the reference example , since the first air 17a is formed in a plurality of areas that are equally spaced in the circumferential direction around the axis a of the rotary atomizing head 24, the second air 17b is moved to the first air 17a side. It can be displaced in a balanced manner. Therefore, the non-coating part of a coating pattern can be reduced effectively and the coating film thickness can be made more uniform.

In the case of the reference example , the air flows along the partition walls 64a and 64b due to the Coanda effect, and the air flows into the first air supply holes 71a disposed in the vicinity of the partition walls 64a and 64b. The wind speed of the first air 17a ejected from the outlet 73a is increased. Further, since the air flow rate flowing to the first buffer chamber 64 and the second buffer chamber 66 may be the same, one flow control system (electropneumatic converter 86, flow meter 88, air control unit 90) and one air source. It is sufficient to provide 80, and the equipment configuration can be simplified.

  The air outlets 68a and 70a described above are constituted by a large number of holes arranged at intervals in the circumferential direction in the ring member 27, but instead of such a configuration, an arc shape extending in the circumferential direction. It may be constituted by a hole (slit).

  The ring member 27 described above has a configuration in which two arc-shaped concave portions (the first arc-shaped concave portion 60 and the second arc-shaped concave portion 62) are provided, but a configuration in which three or more arc-shaped concave portions are provided is adopted. Also good. For example, in the coating apparatus 10 described above, instead of the ring member 27 having the first arc-shaped recess 60 and the second arc-shaped recess 62, the ring member 110 having three arc-shaped recesses 112a to 112c (see FIG. 6A). Or the ring member 120 (refer FIG. 6B) which has four circular arc-shaped recessed parts 122a-122d may be employ | adopted. 6A and 6B, the partition walls 114 and 124 are preferably arranged at equal intervals in the circumferential direction.

  As shown in FIGS. 6A and 6B, even in the case of a configuration in which three or more arc-shaped recesses are provided, the air jetted to the outside through the first air supply holes 71a disposed in the vicinity of the partition walls 114 and 124 The wind speed is higher than the wind speed of the air jetted to the outside through the second air supply hole 71b that is separated from the partition walls 114 and 124 in the circumferential direction, rather than the first air supply hole 71a. Since relatively low wind speed air is attracted to the side, part of the relatively low wind speed air is displaced toward the axis a. Therefore, even when the ring members 110 and 120 are adopted, the non-coating portion generated in the vicinity of the axis a of the rotary atomizing head 24 is reduced while the shape of the coating pattern is maintained in a substantially circular shape, so that a uniform film thickness can be applied. A membrane can be obtained.

Figure 7 is a schematic diagram of a coating apparatus 10a according to the implementation embodiments of the present invention. FIG. 8A is a cross-sectional view taken along line VIIIA-VIIIA in FIG. 7 (however, illustration of the rotary atomizing head 24 is omitted). In addition, in the coating apparatus 10a which concerns on this embodiment, the same referential mark is attached | subjected to the element which shows the same or similar function and effect as the coating apparatus 10 which concerns on a reference example , and detailed description is abbreviate | omitted.

  In the coating gun 130 constituting the main body of the coating apparatus 10a, a plurality (three in the illustrated example) of ring-shaped flow path forming members 132, 134, 136 are disposed between the casing 16 and the air motor 18. . Hereinafter, the flow path forming members 132, 134, and 136 are referred to as “first flow path forming member 132”, “second flow path forming member 134”, and “third flow path forming member 136”, respectively.

  The first flow path forming member 132 is disposed outside the air motor 18, and an annular recess 132 a is formed on the outer peripheral portion thereof, and a plurality of flow paths 132 b penetrating in the axial direction are formed at intervals in the circumferential direction. An annular recess 132c communicating with the flow path 132b is formed on the back side.

  The second flow path forming member 134 is disposed between the first flow path forming member 132 and the casing 16, and a plurality of flow paths 134a penetrating in the direction of the axis a are formed. An annular space 131 is formed by the first flow path forming member 132, the second flow path forming member 134, and the casing 16.

  The third flow path forming member 136 is disposed between the casing 16 and the first flow path forming member 132 and in front of the first flow path forming member 132 and the second flow path forming member 134. The third flow path forming member 136 includes a plurality of flow paths 136a that communicate with the flow path 134a of the second flow path forming member 134 and are spaced apart in the circumferential direction, and the first flow path forming member 132. A plurality of flow paths 136b and 136c are formed in communication with the flow path 132b and spaced apart in the circumferential direction.

  A ring member 140 constituting the air ejection mechanism 138 is fixed to the tip of the third flow path forming member 136 concentrically with the rotary atomizing head 24 so as to surround the bell cup 40 on the back side of the bell cup 40. The annular shaping air 17 is ejected from the rear of the outer peripheral edge of the bell cup 40 toward the outer peripheral edge.

  As shown in FIG. 8A, a first arcuate recess 142, a second arcuate recess 144, and an annular recess 146 are formed on the back surface of the ring member 140. The first arc-shaped recess 142 and the second arc-shaped recess 144 are grooves that are formed inward in the radial direction of the annular recess 146 and extend in the circumferential direction of a circle centered on the axis a, and have substantially the same volume. Have

  An arc-shaped first buffer chamber 150 is formed by the first arc-shaped recess 142 and the front surface of the third flow path forming member 136. An arc-shaped second buffer chamber 152 is formed by the second arc-shaped recess 144 and the front surface of the third flow path forming member 136. An annular third buffer chamber 154 is formed by the annular recess 146 and the front surface of the third flow path forming member 136.

  The ring member 140 further includes a plurality of first air supply holes 158 and 160 communicating with the front surfaces of the first buffer chamber 150 and the second buffer chamber 152 and the ring member 140, and a third buffer chamber 154 and the ring member 140. A plurality of second air supply holes 156 communicating with the front surface of the first air supply hole are formed.

  The first air supply holes 158 are provided at equal intervals in the circumferential direction around the axis a, one end (rear end) is opened in the first buffer chamber 150, and the other end (front end) is on the front surface and one of the first air supply holes 158 is formed. It opens as 1 air jet nozzle 158a. The second air supply holes 160 are provided at equal intervals in the circumferential direction about the axis a, one end (rear end) is opened by the second buffer chamber 152, and the other end (front end) is the front surface and the other second It opens as 1 air jet outlet 160a.

  The second air supply holes 156 are provided at equal intervals in the circumferential direction around the axis a, one end (rear end) is opened by the third buffer chamber 154, and the other end (front end) is the front surface with the second air. It opens as a spout 156a.

  The first air supply holes 158 and 160 are provided on the same circumference inside the second air supply hole 156, and are provided at equal intervals in the circumferential direction. It is slightly inclined so as to approach the 24 axis a, and opens toward the outer peripheral edge of the bell cup 40. The second air supply holes 156 are provided at equal intervals in the circumferential direction, and are slightly inclined toward the front so as to approach the axis a of the rotary atomizing head 24.

  Further, the first air supply holes 158 and 160 and the second air supply hole 156 have a predetermined angle (for example, 30 degrees to about the axis a direction) in the circumferential direction around the axis a of the rotary atomizing head 24. 50 degrees).

  In the coating gun 130 shown in FIG. 7, the first buffer chamber 150 and the flow path 136 b and 136 c of the third flow path forming member 136 and the annular recess 132 c and flow path 132 b of the first flow path forming member 132 described above. A first air supply path 166 that supplies compressed air to the second buffer chamber 152 is configured. The above-described space 131, the flow path 134a of the second flow path forming member 134, and the flow path 136a of the third flow path forming member 136 constitute a second air supply path 162 that supplies compressed air to the third buffer chamber 154. ing.

  The air supply system 170 includes an air source 80, a first air line 172 that guides compressed air from the air source 80 to the first air supply path 166, and a second that guides compressed air from the air source 80 to the second air supply path 162. An air line 174. The air source 80 is the same as the air source 80 shown in FIG.

  A flow meter 176 and an electropneumatic converter 178 are disposed on the first air line 172. The air control unit 180 controls the electropneumatic converter 178 so that the flow rate of air supplied to the first air supply path 166 becomes a predetermined flow rate using the flow rate value detected by the flow meter 176 as a feedback value.

  On the second air line 174, a flow meter 182 and an electropneumatic converter 184 are disposed. The air control unit 186 controls the electropneumatic converter 184 so that the flow rate of air supplied to the second air supply path 162 becomes a predetermined flow rate using the flow rate value detected by the flow meter 182 as a feedback value.

  The compressed air supplied to the coating gun 130 by the first air line 172 passes through the first air supply path 166 and is ejected as the first air 17a from the first air ejection ports 158a and 160a. The compressed air supplied to the coating gun 130 by the second air line 174 passes through the second air supply path 162 and is ejected as the second air 17b from the second air ejection port 156a.

  In the coating apparatus 10a, the first air 17a ejected from the first air ejection ports 158a and 160a is a portion constituting a predetermined portion of the shaping air 17 and has a relatively high wind speed. The 2nd air 17b ejected from the 2nd air ejection port 156a is a part which comprises the other site | part in the shaping air 17, Comprising: It is a relatively low wind speed. That is, the wind speed (flow velocity) of the first air 17a is higher than the wind speed (flow velocity) of the second air 17b.

  Since the total number of the first air supply holes 158 and 160 is smaller than the total number of the second air supply holes 156, the total of the cross-sectional areas of the first air supply holes 158 and 160 is the flow rate of the second air supply holes 156. It is smaller than the sum of the road cross-sectional areas. For this reason, even when the flow rate of the compressed air flowing through the first air line 172 and the flow rate of the compressed air flowing through the second air line 174 are set to be approximately the same, the wind speed of the first air 17a is the same as that of the second air 17b. Higher than. The flow rate of the compressed air flowing through the first air line 172 and the flow rate of the compressed air flowing through the second air line 174 are made different so that the flow rate ratio between the first air 17a and the second air 17b becomes a desired value. May be.

  As will be described later, in the coating apparatus 10a, a part of the second air 17b is attracted by the first air 17a, and as a result, the rotation axis a of the rotary atomizing head 24 is maintained while maintaining the shape of the coating pattern substantially circular. Reduce the non-coating area that occurs in the vicinity. For this reason, the circumferential range in which the first air 17a is formed is preferably set to be considerably smaller than the circumferential range in which the second air 17b is formed. Accordingly, the circumferential range (angle range) in which the first air 17a is formed is preferably about 5 to 45 degrees, for example.

  When coating is performed by the coating apparatus 10a configured as described above, the rotating shaft 20 is rotated at a high speed by the air motor 18, and the paint is applied from the paint supply nozzle 32 toward the paint reservoir 36 of the rotary atomizing head 24. Discharge. Then, after the coating material is thinned at the coating discharge creeping surface 42, it is subdivided at the groove 46 and jumps out from the outer peripheral end of the bell cup 40 as a liquid thread to be atomized as coating particles. At this time, since the shaping air 17 is ejected toward the outer peripheral edge of the bell cup 40 from the first air ejection ports 158a and 160a and the second air ejection port 156a, the atomization of the paint is promoted by the shaping air 17 Is done. The atomized charged paint particles fly toward the workpiece and are applied to the workpiece. The spray pattern of the paint at this time is shaped by the shaping air 17 (first air 17a and second air 17b).

  In this case, in the coating apparatus 10a according to the present embodiment, the first air 17a is formed only in a part of the circumferential direction with respect to the second air 17b inside the annular second air 17b. The wind speed of the 1 air 17a is made higher than the wind speed of the 2nd air 17b. For this reason, the pressure of the first air 17a becomes lower than the pressure of the second air 17b, a part of the second air 17b is drawn toward the first air 17a side, and a part of the second air 17b is displaced toward the axis line side. To do. That is, as indicated by an arrow in FIG. 8B, the first air with a relatively low pressure is provided by shortcutting the inner side of the original ring shape of the second air 17b at each circumferential portion constituting the second air 17b. The action of displacing to the 17a side occurs.

  As a result, the inner peripheral portion of the second air 17b is drawn to a position closer to the axis a side than the original formation region of the second air 17b. And as a result of the inner peripheral part of the 2nd air 17b being drawn near to the axis line a side, a coating material can be apply | coated also to the axis line a vicinity. Therefore, while maintaining the shape of the coating pattern in a substantially circular shape, the non-coated portion generated in the vicinity of the axis a of the rotary atomizing head 24 can be reduced to obtain a coating film with a uniform film thickness, which can be efficiently applied. be able to.

  The first air outlets 158a and 160a in the illustrated example are configured by a large number of holes arranged at intervals in the circumferential direction in the ring member 140, but instead of such a configuration, they extend in the circumferential direction. An arc-shaped hole (slit) may be formed. The second air outlet 156a in the illustrated example is configured by a large number of holes arranged at intervals in the circumferential direction in the ring member 140, but instead of such a configuration, a ring extending in the circumferential direction is provided. It may be configured by a shape hole (slit).

  The ring member 140 described above has a configuration in which two arc-shaped recesses (first arc-shaped recess 142 and second arc-shaped recess 144) are provided, but three or more arc-shaped recesses are provided at equal intervals in the circumferential direction. The first air 17a may be formed at equal intervals in the circumferential direction inside the second air 17b.

In the present embodiment, for each constituent parts common to reference example, it is needless to say that the same or similar action and effect as the action and effects brought about by the common constituent parts in reference example is obtained.

  In the above description, the present invention has been described with reference to preferred embodiments. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention. Yes.

DESCRIPTION OF SYMBOLS 10, 10a ... Coating apparatus 17 ... Shaping air 17a ... 1st air 17b ... 2nd air 24 ... Rotary atomization head 26 ... Air ejection mechanism 73a, 158a, 160a ... 1st air ejection port 73b, 156a ... 2nd air injection Exit

Claims (4)

A coating method of coating the workpiece by directing the paint discharged from the rotating rotary atomizing head to the workpiece side by annular shaping air,
The predetermined portion in the shaping air is the first air, and is ejected at a relatively high wind speed.
In parallel with the ejection of the first air, the other part of the shaping air is the second air, and is ejected at a lower wind speed than the first air,
The second air is attracted to the first air side to displace a part of the second air to the rotation axis side of the rotary atomizing head, and is substantially circular around the rotation axis of the rotary atomizing head. the coating pattern is formed,
The second air is formed in an annular shape,
The first air is formed only in a partial range in the circumferential direction with respect to the second air inside the second air.
A painting method characterized by that. In the coating method of claim 1 Symbol placement,
Forming the first air in a plurality of equally spaced areas in the circumferential direction around the rotation axis of the rotary atomizing head;
A painting method characterized by that. A rotary atomizing head that discharges paint onto the workpiece;
A coating apparatus comprising an air ejection mechanism that ejects annular shaping air toward the outer peripheral edge of the rotary atomizing head,
The air ejection mechanism is
A first air outlet and a second air outlet for ejecting the shaping air;
A plurality of buffer chambers provided on the upstream side of the first air outlet and the second air outlet, and partitioned by a partition;
First air having a relatively high wind speed is ejected from the first air outlet,
The second air having a lower wind speed than the first air is ejected from the second air ejection port,
The second air is attracted to the first air side to displace a part of the second air to the rotation axis side of the rotary atomizing head, and is substantially circular around the rotation axis of the rotary atomizing head. the coating pattern is formed,
The second air outlet is provided to form the second air in an annular shape,
The first air ejection port is provided so as to form the first air only in a partial range in the circumferential direction with respect to the second air inside the second air .
A painting device characterized by that. The coating apparatus according to claim 3 ,
The first air outlet is provided so as to form the first air in a plurality of areas that are equidistant from each other in the circumferential direction around the rotation axis of the rotary atomizing head.
A painting device characterized by that.

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