JP5565080B2 - Powder coating apparatus and powder coating method - Google Patents

Description

  The present invention relates to a powder coating apparatus and a powder coating method using a fluidized immersion method.

  Powder coating by fluid immersion method, that is, powder coating can be performed by immersing the preheated object to be coated in the powder powder in the powder flow tank and fusing the paint to the surface of the object to be coated. It is known (for example, refer nonpatent literature 1). The powder flow tank used for the flow dipping method usually includes a plenum chamber provided adjacent to the bottom surface of the powder storage section and a perforated plate for partitioning them so as to allow fluid communication. The stored powder coating is fluidized by the air supplied from the plenum chamber through the perforated plate.

Japan Painting Technology Association, “Coating Technology Handbook”, Nikkan Kogyo Shimbun, February 20, 1989, p. 308

  By the way, there is a case where a coating region and a coating prohibition region where adhesion of coating powder is not allowed are provided on the object to be coated, and only the coating region is powder-coated by a fluidized immersion method. In that case, it is necessary to manage the immersion depth so that the paint does not adhere to the paint prohibited area. However, in the fluid immersion method, bubbles formed by air ejected from fine holes in the perforated plate make the density of the powder non-uniform and cause unevenness on the fluidized surface of the powder, thereby increasing the height of the fluidized surface. As a result, relatively large fluctuations in the immersion depth were caused. Therefore, in the powder coating apparatus or the powder coating method according to the prior art, it is necessary to set the dimensional tolerance of the coating region to be considerably large. However, in the recent situation where the object to be coated is downsized, it has been desired to reduce the dimensional tolerance of the coating region.

  The present invention has been made in view of the above-described problems of the prior art, and an object thereof is to provide a powder coating apparatus and a powder coating method capable of improving the dimensional accuracy of a coating region of an object to be coated. .

In order to solve the above-mentioned problem, the invention according to claim 1 is a powder coating apparatus for coating a coating region (a) partially provided on an object to be coated (W) by a flow dipping method. A powder storage section (21) that includes an upper opening (24) that allows the object (W) to advance and retreat, and that stores powder (P) made of powder paint, and a powder storage section ( 21) A powder flow tank (22) having a plenum chamber (22) provided on the lower side, and a porous plate (23) partitioning the powder reservoir (21) and the plenum chamber (22) in fluid communication. 20) and horizontal vibration means (30) for vibrating the powder flow tank (20) in the horizontal direction, and the horizontal vibration means (30) is composed of a rotary vibrator, In the vibrator (30), the position of the rotation axis (Ra) of the rotor (32) is horizontal to the powder flow tank (20). Is fixed to the powder fluidization vessel (20) at a position shifted from the center in the direction, the air from the plenum chamber (22) into the powder reservoir (21) through the porous plate (23) is supplied, and flour While the body fluid tank (20) is vibrated in the horizontal direction by the horizontal vibration means (30), only the painting area (a) of the painting object (W) is painted. ) Is partially immersed in the powder (P), and a powder coating apparatus is provided.

  According to the present invention, it was observed that the bubbles formed by the air ejected through the perforated plate (23) were reduced and the size thereof was reduced to reduce the irregularities of the flow surface. As a result, the dimensional accuracy of the coating area (a) of the article (W) to be coated can be increased. In this way, the bubbles are reduced and the size is reduced and the irregularities of the flow surface are reduced. This is because the horizontal vibration force applied to the powder flow tank (20) causes the powder (P) and air. This is thought to be due to the promotion of mixing with

  In invention of Claim 2, it is stored by the powder storage part (21) to the limit which powder (P) overflows. According to this, detection of the height of the flow surface of the powder (P) becomes unnecessary, and the error of the height of the flow surface can be made substantially zero except for the one based on the flatness. .

  In the invention according to claim 3, the second porous plate (72) disposed in the plenum chamber (22) facing the porous plate (23), and the holes constituting the porous plate (23) are used. The powder flow tank (20) further includes a second perforated plate (72) having a larger hole. Thereby, it is possible to further increase the flatness of the flow surface of the powder. This is because the action of the second perforated plate (72) arranged in the plenum chamber further promotes equalization of air pressure acting on the surface of the perforated plate (23), and fluidized powder (P). This is thought to be due to the increased uniformity of density.

  In the invention according to claim 4, the size of the powder reservoir (21) is such a size that only one object (W) can be immersed.

The invention according to claim 5 is a powder coating method for powder coating a coating region (a) partially provided on an object to be coated (W) by a fluid dipping method. ) is have a powder reservoir, which is stored (21), preparing a powder flow bath horizontal vibration means (30) is fixed (20), the porous plate from the plenum chamber (22) ( 23) supplying air into the powder reservoir (21) through 23) and vibrating the powder flow vessel (20) in the horizontal direction by the horizontal vibration means (30), and during the step of vibrating And a step of partially immersing the object to be coated (W) in the powder (P) so that the powder (P) adheres to the coating region (a) of the object to be coated (W). after time has elapsed, it includes the steps of retrieving the object to be coated (W) is from the powder (P), a horizontal vibrating means (30) times The vibrator (30) has a powder flow at a position where the rotational axis (Ra) of the rotor (32) deviates from the center in the horizontal direction of the powder flow tank (20). A powder coating method is provided which is fixed to a tank (20) .

  When the powder coating method was used, it was observed that the bubbles formed by the air ejected through the perforated plate (23) were reduced and the size thereof was reduced to reduce the irregularities of the fluid surface. As a result, the dimensional accuracy of the coating area (a) of the article (W) to be coated can be increased.

  In the sixth aspect of the present invention, in the step of preparing the powder flow tank (20), the powder (P) is stored in the powder storage section (21) to at least the limit of overflow. According to this, detection of the height of the flow surface of the powder (P) becomes unnecessary, and the error of the height of the flow surface can be made substantially zero except for the one based on the flatness. .

  In addition, the code | symbol in the bracket | parenthesis of each said means is an example which shows a corresponding relationship with the specific means as described in embodiment mentioned later.

It is a front view before the coating of the stator of the rotary electric machine which is a to-be-coated object to which the powder coating apparatus and powder coating method by this invention are applied. It is a front view after the coating of the stator. FIG. 3 is an enlarged detail view of a part C in FIG. 1B. It is front sectional drawing of the principal part of the powder coating apparatus of 1st Embodiment by this invention. It is a front view which shows the relationship between the powder coating apparatus of 1st Embodiment, its support structure, and a foundation. It is a top view of the powder coating apparatus shown by FIG. 3A and its support structure. It is front sectional drawing of the principal part of the powder coating apparatus of 2nd Embodiment. It is front sectional drawing of the principal part of the powder coating apparatus of 3rd Embodiment.

  First, the article W to which the powder coating apparatus and the powder coating method according to the present invention are applied will be described. In the present specification, the invention will be described using the stator W of the rotating electric machine shown in FIGS. 1A, 1B, and 1C as an example of the article W to be coated. However, it is needless to say that the present invention can be applied to objects other than the stator W.

  FIG. 1A shows a stator W before painting, and the stator W includes a stator core W1 and a winding W2. FIG. 1B shows the stator W after painting. As shown in this figure, the winding W2 is partially provided with a coating region a on the lower end side thereof, and the coating region a is powdered with an epoxy resin. It is a painting-prohibited area b where the body is painted and the area other than the painted area a is not allowed to adhere to the paint. In the example of this figure, the epoxy resin coating formed by powder coating functions as an insulating coating. Further, in this example, as shown in FIG. 1C, which is an enlarged detailed view of part C in FIG. 1B, the boundary line between the coating region a and the coating prohibited region b is 2.75 mm downward from the end of the stator core W1. It extends horizontally with a tolerance of ± 1.25 mm.

Next, the powder coating apparatus 10 according to the first embodiment of the present invention will be described with reference to FIG. 2 which is a cross-sectional front view of an essential part thereof, and FIGS. 3A and 3B which are schematic front views and plan views.
The powder coating apparatus 10 of 1st Embodiment is equipped with the powder flow tank 20 and the horizontal vibration means 30 for vibrating the said powder flow tank 20 in a horizontal direction as main components. . The powder coating apparatus 10 shown in FIG. 2 also includes a support structure 40 for fixing it to a foundation B such as a floor surface, and a powder supply apparatus 50 for supplying powder. .

  The powder flow tank 20 has a powder storage unit 21 for storing an epoxy resin powder P (hereinafter referred to as “powder P”), which is a powder coating, in order to perform powder coating by a fluid immersion method. A plenum chamber 22 provided on the lower side of the powder storage portion 21 and a porous plate 23 that partitions the powder storage portion 21 and the plenum chamber 22 so as to allow fluid communication are provided.

  The powder storage unit 21 has a rectangular upper opening 24 through which a workpiece W gripped by a workpiece conveying device (not shown) advances and retreats. In the embodiment, the size is such that only one workpiece W can pass through. In addition, a flange-like portion 25 that is larger than the upper opening 24 is formed at the bottom of the powder storage portion 21, and the powder storage portion 21 has a porous plate 23 or the like in the flange-like portion 25. The bolts 29 are fixed to the side wall portions 26 that sandwich the plenum chamber 22. However, the powder storage unit 21 does not have a bottom surface for supporting the powder P, and therefore the powder P is supported by the porous plate 23.

  In this embodiment, the perforated plate 23 has a rectangular planar shape, and is provided with a large number of fine holes (not shown) of about φ0.01 mm. Further, a reinforcing frame plate 23 a is attached to the lower surface side of the porous plate 23, and the porous plate 23 together with the frame plate 23 a forms a powder reservoir 21 and a plenum chamber 22 using bolts 29. It is sandwiched and fixed between the side wall portions 26.

  The plenum chamber 22 in the present embodiment is formed in a rectangular parallelepiped shape by a side wall portion 26, a bottom plate portion 27, and a porous plate 23 disposed on the side wall portion 26. An air inlet 28 is provided in the right side wall portion 26 of the plenum chamber 22 in the drawing, and an air supply source (not shown) that can supply high-pressure air of a constant pressure to the air inlet 28. The pipe line 60 connected to is connected. Therefore, when high-pressure air is supplied from the air supply source into the plenum chamber 22, air with substantially uniform pressure is ejected from the high-pressure plenum chamber 22 through the fine holes of the porous plate 23 toward the powder storage unit 21. To do.

  The horizontal vibration means 30 in this embodiment is composed of a rotary vibrator 30, and this vibrator 30 is fixed to the outer surface of the bottom plate portion 27 of the plenum chamber 22 of the powder flow tank 20 by a bracket 31. The vibrator 30 includes a rotor 32 having a center of gravity eccentric from the rotation axis Ra, and the rotation axis is rotated by rotating the rotor 32 with high-pressure air supplied from an air pipe (not shown). A vibration force is generated in each direction orthogonal to Ra. Accordingly, as shown in FIG. 2, the vibrator 30 is fixed to the powder coating apparatus 20 so that the rotation axis Ra of the rotor 32 of the vibrator 30 faces in the vertical direction, thereby vibrating the powder flow tank 20 in the horizontal direction. Can be made.

  Moreover, in this embodiment, since the direction of the vibration force of the rotary vibrator 30 rotates and changes, the powder flow tank 20 basically performs a turning motion. However, as shown in FIG. 3B, the position of the rotation axis Ra of the rotor 32 does not coincide with the center of the powder flow tank 20 or the center of the virtual rectangle formed by the four rubber bushes 43, and the support structure. Since the rigidity of the body 40 is directional, the powder flow tank 20 vibrates not by a turning motion along a circular orbit but by a turning motion along a substantially elliptical orbit.

  FIG. 3A is a front view illustrating a relationship among the powder coating apparatus 10, the support structure 40, and the foundation B according to the first embodiment, and FIG. 3B is a plan view thereof. 3A and 3B, the drawing of the powder supply device 50 and the like shown in FIG. 2 is omitted.

  As shown in FIGS. 3A and 3B, the support structure 40 includes a groove-shaped member 41 that is fixed to the base B surface and a flat plate member 42 that is coupled to the bottom plate portion 27 of the plenum chamber 22 of the powder flow tank 20. The flat plate member 42 and the upper portion of the groove-shaped member 41 are fixed with bolts 44 via two cylindrical rubber bushes 43 on each of the left and right sides. The rubber bush 43 in this embodiment is used for vibrating the powder flow tank 20 with a predetermined amplitude and for preventing vibrations from being transmitted to the foundation B. However, if the vibration isolating function is not required, a support structure that does not include such a rubber bush 43 is also possible, and in that case, a support corresponding to a desired amplitude of vibration of the powder flow tank 20 is possible. What is necessary is just to prepare the support structure which can obtain the rigidity of the whole structure.

  Returning to FIG. 2 again, the powder supply device 50 will be described. The powder supply device 50 is fixed to the hopper 51 for supplying the powder P from the upper opening 24 of the powder reservoir 21 and the side wall 26 of the powder flow tank 20 for supporting the hopper 51. A substantially Z-shaped support frame 52, and a powder supply vibrator 53 connected to an upper portion of the support frame 52 to promote the fall of the powder P. The powder supply device 50 supplies the powder P in accordance with the height of the flow surface of the powder P in the powder reservoir 21 detected using, for example, a liquid level sensor (not shown) using laser light. The powder storage unit 21 is replenished.

  Next, the operation of the powder coating apparatus 10 according to the first embodiment of the present invention will be described below based on an example of a powder coating method using the same.

  First, a predetermined amount of powder P is prepared in the powder storage unit 21. Here, the predetermined amount is an amount in which the height of the flow surface determined by the powder P fluidized with air indicates the predetermined height. Further, the predetermined height is a height corresponding to the boundary line between the coating area a and the coating prohibition area b of the submerged article W, and it takes into account the increase due to the volume of the immersion coating area a. In the example shown in FIG. 2, the height is about 80% of the maximum height to the upper end edge 21 a of the powder reservoir 21.

  Next, by supplying high-pressure air from the air supply source into the plenum chamber 22, the air is ejected into the powder storage unit 21 through the porous plate 23.

  Next, the powder vibrator 20 is vibrated in the horizontal direction by operating the rotary vibrator 30. At this time, in this embodiment, the powder flow tank 20 vibrates at a vibration frequency of 400 to 500 rpm and an amplitude of about 0.02 mm.

  Next, while continuing the fluidization of the powder P by the air and the vibration in the horizontal direction, one object to be coated W preheated to about 180 ° C. in a preheating furnace (not shown) is applied to the object to be coated. After being conveyed above the powder reservoir 21 using a painted object conveying device (not shown), the object to be coated W is partially immersed in the powder P by being moved downward. At this time, the descending distance of the article transport device is determined so that only the coating area of the article W is immersed in the powder P. Instead, the descending distance of the article conveying device (not shown) may be controlled according to the height of the fluid surface detected by the liquid level sensor (not shown).

  After the time stipulated by the required film thickness has elapsed, the workpiece W is lifted and lifted out of the powder P by a workpiece transfer device (not shown), and then moved to another place for natural movement. dry. Or depending on the kind of coating material, the to-be-coated object W may be pulled up from the powder storage part 21, and may be conveyed to a baking furnace (not shown).

  Thus, the powder coating for one object W is completed. Next, the height of the flow surface is detected by a liquid level sensor (not shown), and if it is lower than a predetermined lower limit height, the powder P is supplied by the powder supply device 50. Further, in order to efficiently process one subsequent preheated workpiece W in the same manner, normally, the fluidization of the powder P by the air and the vibration in the horizontal direction are normally continued without stopping. Keep it.

  When the powder coating apparatus 10 or the powder coating method according to the above-described embodiment was used, it was observed that the bubbles were reduced and the size thereof was reduced to reduce the unevenness of the fluidized surface. This is considered due to the fact that mixing of the powder P and air is promoted due to the horizontal vibration force applied to the powder flow tank.

  Next, a powder coating apparatus 200 according to a second embodiment of the present invention will be described with reference to FIG. The powder coating apparatus 200 of this embodiment is structurally almost the same as the powder coating apparatus 10 of the first embodiment shown in FIG. It reaches the upper edge 21a and is stored in the powder storage unit 21 up to the limit of overflow, and when the powder P overflows from the powder storage unit 21, it is received around the powder storage unit 21. It is different by providing the powder receiver 71 formed on the flange-like portion 25 of the powder storage part 21.

  In the second embodiment, since the powder reservoir 21 is filled with the powder P reaching the upper edge 21a, the height of the powder flow surface is always kept constant. Even if the powder P temporarily rises in a mountain shape beyond the upper end edge 21a of the powder storage portion 21, excess powder can be obtained by fluidizing the powder P with air and vibrating it horizontally. P overflows, and the height of the flow surface of the powder P becomes the same level as the upper end edge 21 a of the powder reservoir 21. Therefore, when the powder coating apparatus 200 according to the second embodiment is used, it is not necessary to detect the height of the flow surface of the powder P, and the error in the height of the flow surface is based on the flatness. In principle, it becomes zero. In addition, when the powder P is replenished using the powder supply device 50, the height of the fluidized surface is maintained constant even if the powder P is replenished so much that it overflows. Management of replenishment amount becomes easy. The powder P that overflows from the powder storage unit 21 and is collected by the powder receiver 71 can normally be reused.

  Next, the powder coating apparatus 300 of 3rd Embodiment is demonstrated with reference to FIG. The powder coating apparatus 300 of this embodiment is different from the powder coating apparatus 200 of the second embodiment described above in that it further includes a second porous plate 72 inside the plenum chamber 22. In the present embodiment, the second perforated plate 72 has a large number of holes having a size of φ2 mm which is much larger than the holes of about φ0.01 mm of the above-described perforated plate 23 (hereinafter referred to as “first perforated plate 23”). It is a drilled board. The second perforated plate 72 is disposed above the air inlet 28 of the plenum chamber 22 so as to face the first perforated plate 23 in parallel. As a result, the plenum chamber 22 includes the air inlet 28. It is partitioned into a lower space 22L and an upper space 22U in contact with the first perforated plate 23.

  When the powder P is fluidized using the powder fluidization tank 20 of the powder coating apparatus 300 of the third embodiment, the flatness of the fluidized surface of the powder P is higher than in the first and second embodiments. A further increase was observed. This is because the addition of the second perforated plate 72 further promotes the equalization of the air pressure acting on the surface of the first perforated plate 23. As a result, the density of the fluidized powder P is uniform. This is thought to be because of increased sex.

  Various modifications of the above-described embodiment according to the present invention are possible. For example, a second porous plate 72 may be added to the powder coating apparatus 10 of the first embodiment.

  In the description of the first embodiment, the amplitude and frequency of vibration of the powder flow tank 20 are shown. However, the amplitude and frequency can increase the flatness of the fluidized surface of the powder P. It is not particularly limited as long as it is within the range, and the optimum value varies depending on conditions such as the material of the powder P, the storage amount, the particle size, and the supply air amount.

  In the above-described embodiment, air is used as a gas for fluidizing the powder P. However, an inert gas such as nitrogen or argon may be used instead of air.

DESCRIPTION OF SYMBOLS 20 Powder flow tank 21 Powder storage part 21a Upper end edge 22 Plenum chamber 23 Perforated plate 24 Upper opening 25 Flange part 26 Side wall part 28 Air inlet 30 Horizontal vibration means 40 Support structure 41 Groove-shaped member 42 Flat plate member 43 Rubber bushing 50 Powder supply device 60 Pipe line a Painting area P Powder W Object to be coated

Claims (6)

A powder coating device for powder coating a coating region (a) partially provided on a workpiece (W) by a fluid immersion method,
The powder storage part (21) which has the upper opening (24) which can advance / retreat the said to-be-coated object (W), and stores the powder (P) which consists of powder coating materials, and the said powder storage part (21) A powder flow tank (22) having a plenum chamber (22) provided on the lower side, and a perforated plate (23) partitioning the powder reservoir (21) and the plenum chamber (22) in fluid communication. 20), and horizontal vibration means (30) for vibrating the powder flow tank (20) in a horizontal direction,
The horizontal vibration means (30) is composed of a rotary vibrator,
The vibrator (30) is fixed to the powder flow tank (20) at a position where the rotational axis (Ra) of the rotor (32) is shifted from the center in the horizontal direction of the powder flow tank (20). And
Air is supplied from the plenum chamber (22) through the perforated plate (23) to the powder reservoir (21), and the powder flow tank (20) is horizontal by the horizontal vibration means (30). While being vibrated in the direction, the object to be coated (W) is partially in the powder (P) so that only the coating region (a) of the object to be coated (W) is coated. A powder coating apparatus characterized by being immersed.   The powder coating apparatus according to claim 1, wherein the powder (P) is stored in the powder storage part (21) up to a limit where the powder (P) overflows.   The second perforated plate (72) disposed in the plenum chamber (22) opposite to the perforated plate (23) was configured with holes larger than the holes constituting the perforated plate (23). The powder coating apparatus of Claim 1 or 2 with which the said powder flow tank (20) further has a 2nd perforated plate (72).   The magnitude | size of the said powder storage part (21) is a magnitude | size which can immerse only the said to-be-coated article (W), It is any one of Claims 1-3 characterized by the above-mentioned. The powder coating apparatus as described. A powder coating method for coating a coating region (a) partially provided on an object to be coated (W) by a fluid immersion method,
The method comprising the powder (P) is closed by a powder reservoir (21) storing, preparing a powder flow bath (20) for horizontal vibration means (30) is fixed,
Air is supplied from the plenum chamber (22) through the perforated plate (23) into the powder reservoir (21) and the powder flow tank (20) is horizontally moved by the horizontal vibration means (30). Exciting, and
During the step of vibrating, the object to be coated (W) is placed in the powder (P) so that the powder (P) adheres to the coating region (a) of the object to be coated (W). Partially immersing,
After a predetermined time has elapsed, the step of taking out the article (W) from the powder (P) ,
The horizontal vibration means (30) is composed of a rotary vibrator,
The vibrator (30) is fixed to the powder flow tank (20) at a position where the rotational axis (Ra) of the rotor (32) is shifted from the center in the horizontal direction of the powder flow tank (20). The powder coating method.   The said stage which prepares the said powder flow tank (20) WHEREIN: The said powder (P) is stored by the said powder storage part (21) to the limit which overflows at least, The Claim 5 characterized by the above-mentioned. Powder coating method.

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