JP2002113409A - Powder feeder and powder coating system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a powder feeder used in conjunction with a powder coating system using specified particles and adapted so that it may selectively feed specified particles into the system by establishing a stable particle size distribution in the system. SOLUTION: An air cylinder 15 is operated to vertically drive the powder suction port 143 of an ejector 14 within the upper space 11a of a powder feed tank 11. This enables the selective collection of only particles with nearly constant particle diameters. When the particles left in the tank 11 entirely become coarse ones, the coarse ones are pulverized by means of a pulverizer 50, and the product of pulverization is returned to the powder feeder 10 to restore the distribution of the particles in the tank.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a powder supply apparatus and a powder coating system used for powder coating, and in particular, to selectively apply a specific powder to an article to be coated. In this case, the present invention relates to a means for selectively supplying a specific powder and a technique for stably and selectively supplying a specific powder.

[0002]

2. Description of the Related Art Compared with conventional solvent-based coatings and water-based coatings, powder coatings are solvent-free and liquid-free, are easy to collect and have good recyclability, and have a simple process. There are many advantages, such as becoming. For this reason, in recent years, it has attracted attention as a technique corresponding to global environmental conservation, particularly as a coating technique in the field of automobiles. However, in this field, since the finished appearance has been particularly required conventionally, it is necessary to obtain the same level of coating surface smoothness as in the case of the solvent type coating. In order to obtain a smooth surface in powder coating,
It is effective to increase the thickness of the coating film, but it is disadvantageous in terms of cost. Therefore, it is required to improve the smoothness of the thin film. For this reason, an attempt has been made to apply a coating material having a small diameter to improve the smoothness of the coated surface by coating the article to be coated with coating particles having a small diameter.

[0003] In a coating method called an electrolytic flowing immersion method, paint particles are suspended in a tank, and a potential difference is provided between an object to be coated and an electrode, thereby utilizing the static electricity of the suspended particles. This is a method of applying paint particles to an object to be coated. According to this method, it is possible to selectively attach particles having a small diameter to the object to be coated by adjusting the air conditions for suspending the particles, adjusting the height of the object to be coated in the tank, etc. Coating with improved smoothness of the coated surface can be realized.

In the case of performing the powder coating by the electrolytic fluidized immersion method as described above, since the coating particles adhere to the article to be coated and the suspended particles in the tank decrease with time, the coating powder is supplied. It is necessary to supply the powder using an apparatus (powder supply device).

[0005] Japanese Patent Application Laid-Open No. 10-180 discloses a powder supply apparatus.
152 and JP-A-11-216417. What is described in the former publication,
The use of the compaction of powder by a screw realizes the quantitative supply of powder. In the latter publication, in order to promote the fluidization of the powder in the powder supply tank and to supply the powder stably, the vibrating means is devised so that the perforated plate and the powder This is to generate a uniform horizontal circular vibration over the entire contact surface.

[0006]

When the powder coating is carried out by the electrolytic fluidized immersion method, the necessary particles can be selectively adhered to the article to be coated as described above. Of the particles is used, and the particle size distribution of the particles remaining in the tank changes with time. In order to prevent this, it is necessary to selectively supply only the specific particles used in the powder supply device, but in the powder supply device described above, quantitative or stable Although powder can be supplied in a specific manner, it is not possible to selectively supply only specific particles.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has a powder supply device for selectively supplying specific particles and a system for performing powder coating using specific particles. Another object of the present invention is to maintain the coating quality by stably supplying specific particles selectively.

[0008]

Means for Solving the Problems To solve the above technical problem, the invention of claim 1 is directed to a powder supply tank, and a powder supply tank disposed inside the powder supply tank. A perforated plate for partitioning the internal space into an upper space and a lower space, a pressurizing means introduced into the lower space to increase the pressure in the lower space, and a powder suction port protruding into the upper space. A powder supply device comprising: a powder suction unit having the powder suction port; and a driving unit configured to drive the powder suction port vertically in the upper space.

According to the first aspect of the present invention, when the powder is filled in the upper space of the powder supply tank and the pressure in the lower space is increased by pressurizing means, the gas in the lower space causes the perforated plate to move. Spouts out into the upper space and winds up the powder in the upper space. At this time, the powder suction port is driven up and down in the upper space, so that powder can be captured at an arbitrary position in the upper space. The height of the rolled-up powder changes due to its own weight. Heavy particles having a large diameter float in a lower region in the upper space, and light particles having a small diameter float in an upper region in the upper space. Therefore, for example, if the powder suction port is driven and disposed above the upper space, only light particles having a small diameter can be captured. In this way, specific particles can be captured and selectively supplied.

In order to solve the above technical problem, the invention according to claim 2 is directed to a powder supply tank and an internal space of the powder supply tank which is disposed inside the powder supply tank. A perforated plate for partitioning into a space and a lower space, pressurizing means introduced into the lower space to increase the pressure in the lower space, and a powder suction having a powder suction port protruding into the upper space Means, a powder supply device comprising: a driving means for driving the powder suction port in the upper space in the vertical direction; and a powder coating apparatus connected to the powder suction means by a first passage. A crushing device connected to the powder suction means through a second passage, a first opening / closing valve disposed in the middle of the first passage, and a crushing device disposed in the middle of the second passage. A second on-off valve; and a powder coating system comprising: A.

According to the second aspect of the present invention, by opening the first opening / closing valve and closing the second opening / closing valve, specific particles caught by the powder supply device can be discharged from the first passage. It is supplied to the powder coating equipment. On the other hand, when the specific particles are reduced in the powder supply device, the first opening / closing valve is closed and the second opening / closing valve is opened. Thereby, the coarse powder in the powder supply device is supplied to the crushing device through the second passage and is pulverized. By returning the pulverized powder to the powder supply device again, the particle size distribution in the powder supply device is maintained. Therefore, in a system that performs powder coating using specific particles, the selective supply of specific particles,
The coating can be performed stably, and the coating quality can be maintained.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an overall schematic diagram of a powder coating system according to an embodiment of the present invention. As shown in the figure, the powder coating system 100 in this example
And an electrolytic fluidized immersion coating device 30 and a crushing device 50. One end of a powder discharge passage 61 communicates with the powder coating supply device 10.
The other end of 1 is branched into a first passage 62 and a second passage 63 as shown in the figure. The first passage 62 is connected to the electrolytic fluidized immersion coating device 30 at a point, and the second passage 63 is connected to the pulverizing device 50 at a point. A first opening / closing valve 71 is provided in the middle of the first passage 62, and a second valve 72 is provided in the middle of the second passage 63.
Further, the powder coating supply device 10 includes a powder return passage 64.
Are connected at one end. The other end of the powder return passage 64 is connected to the crushing device 50, and the fine powder particles crushed to a specific size by the crushing device 50 are returned to the powder supply device 10 through the powder return passage 64. It is supposed to be.

FIG. 2 is a schematic sectional view of the powder supply device 10. As shown in the figure, a powder supply device 10 includes a powder supply tank 11, a perforated plate 12, an air ejection nozzle 13 as a pressurizing means, and an ejector 14 as a powder suction means.
And an air cylinder 15 as driving means for driving the powder suction port 14a of the ejector 14.

The powder supply tank 11 comprises an upper case 111 and a lower case 112. Upper case 111
The flange 111a extends outward in the horizontal direction at the lower end of the
Are formed. A flange 112a extending outward in the horizontal direction is also formed at the upper end of the lower case 112. These flange portions 111a and 112a are arranged so as to face each other, and they are integrally fixed by fastening with a fastening means (not shown) in a state where the porous plate 12 is sandwiched between both flange portions.

The perforated plate 12 is provided with the upper case 1 as described above.
11 and the flange 112 a of the lower case 112. Therefore, as shown in the figure, the space in the powder supply tank 11 is partitioned into an upper space 11a and a lower space 11b by the perforated plate 12.

The air jet nozzle 13 is provided in the lower space 11b.
Introduced within. This air jet nozzle 13
Has a large number of air ejection holes 13a formed on a side surface thereof. When high-pressure air is sent from an air source (not shown) to the air ejection nozzle 13, air is ejected from the air ejection holes 13a to the lower space 11b. As a result, the pressure in the lower space 11b is increased.

An ejector 14 as a powder suction means is attached to the upper portion of the powder supply tank 11 in the figure. The ejector 14 includes an air suction passage 141 and a powder suction passage 142. Powder suction passage 1
Reference numeral 42 projects from the upper side of the tank 11 into the inside of the tank.
The powder suction port 143 protruding from the a is formed.
The powder suction port 143 is formed in a flat shape extending in the horizontal direction so as to uniformly capture powder particles floating at a horizontal position in the upper space 11a. Further, the air suction passage 141 and the powder suction passage 142 are
Although they merge at the base end side, the cross-sectional area of the merge portion is reduced as shown in the figure. Therefore, the air suction passage 141 is connected to an air source or the like, and the air suction passage 141 is connected.
When air flows from left to right in the figure as shown by the arrow,
Since air expands in a portion where the cross-sectional area is reduced, a negative pressure is generated in this portion. Utilizing this negative pressure, the powder in the powder suction passage 142 is sucked.

The powder supply tank 11 is mounted on a base 15. A vibrator 16 is also placed on the base 15, and the powder supply tank 11 is vibrated by the vibration of the vibrator 16 to agitate the powder in the tank.

The outlet port 144 of the ejector 14 is connected to one end of the powder discharge passage 61. As described above, the other end of the powder discharge passage 61 is branched into the first passage 62 and the second passage 63, and the first passage 62 is connected to the electrolytic fluid immersion coating device 30 at the other end. , The second passage 63
Is connected to the pulverizer 50 at the end. Also, the first
A first opening / closing valve 71 is provided in the middle of the passage 62, and a second valve 72 is provided in the middle of the second passage 63.

The ejector 14 is connected to a rod 15a of an air cylinder 15 as a driving means by a connecting rod 17.
It is linked to The air cylinder 15 is connected to the upper case 11
1 is fixed to a side surface by a bracket, and a rod 15a
Are driven in the vertical direction. Accordingly, when the air cylinder 15 is driven and the rod 15a is driven in the vertical direction, the ejector 14 is driven in the vertical direction. For this reason, the powder suction port 143 of the ejector 14
Is also driven up and down in the upper space 11a.

In the powder coating system having the above configuration, first, the upper space 11 of the powder supply tank 11 of the powder supply device 10
a is filled with powder. Next, high-pressure air is blown from the air ejection hole 13a of the air ejection nozzle 13 provided in the lower space 11b. Thereby, the lower space 1
The inside of 1b becomes high pressure. Filled powder is deposited on the perforated plate 12 and acts as a lid for the lower space 11b. However, when the pressure in the lower space 11b exceeds a certain pressure level, High-pressure air is blown into the upper space 11a through the plate. The air filled in this way causes the powder filled in the upper space 11a to flow and be wound up.

The suspended height of the wound powder in the upper space 11a changes depending on its own weight. That is,
Heavy, large-diameter particles are suspended at a low position without being rolled up to a very high position, while light, small-diameter particles are raised to a high position and suspended at a high position.
Accordingly, in the upper space 11a, particles having a smaller diameter are floating as the position is higher, and particles having a larger diameter are floating as the position is lower. Further, the diameter of the particles floating at a certain height position is substantially the same.

Therefore, the air cylinder 15 is driven to move the powder suction port 143 of the ejector 14 into the upper space 11a.
By driving the powder suction port 143 in the vertical direction and arranging the powder suction port 143 at a desired height, only particles having a desired diameter can be captured. The particles thus captured enter the powder discharge passage 61 from the ejector 14. Here, if the first opening / closing valve 71 is opened and the second opening / closing valve 72 is closed, the powder flows from the powder discharge passage to the first opening / closing valve.
Is supplied to the electrolytic fluidized immersion coating apparatus.

The powder supplied to the electrolytic fluidized immersion coating apparatus has a uniform diameter as described above. Therefore, by supplying only the powder having a small diameter to the electrolytic fluidized immersion coating apparatus, only the powder having a small diameter can be adhered to the article to be coated, and a thin film can be achieved. Also,
Since the diameter of the powder forming the coating film is small, improvement in the smoothness of the coating film can be expected.

When the powder supply device 10 captures, for example, only powder having a small diameter, the particles having a small diameter disappear in the tank, and only powder having a large diameter is left. In this state, the air cylinder 15 is driven to drive the powder suction port 143 downward, and the upper space 11a
The suction port 143 is sunk into the powder accumulated in the lower part of the box, and the accumulated powder is sucked. The powder thus captured is transferred from the ejector 14 to the powder discharge passage 6.
Enter 1. Here, if the first on-off valve 71 is closed and the second on-off valve 72 is open, the powder is supplied from the powder discharge passage through the second passage 63 to the pulverizer.

The powder supplied to the pulverizer is pulverized by the pulverizer to be refined. Then, the finely divided powder is returned to the powder supply device 10 through the powder return passage 64.

(Experimental Example) In the powder supply apparatus 10 shown in FIG. 2, when the height position (collection position) of the powder suction port 143 in the upper space 11a is variously changed, the collected particles The average particle size and particle size distribution were investigated. Table 1 shows the survey results. In Table 1, the collection position is the upper space 11
a is the height from below, and the average particle diameter is the particle diameter Dp50 when the cumulative percentage under the sieve is 50%.
(Volume average diameter), and the SD value is an index indicating a sharp difference in particle size distribution, and is given by the following equation.

SD value = (Dp90-Dp10) / Dp5
The smaller the 0SD value, the sharper the particle size distribution and the more uniform the particle size.

In the above formula, Dp90 is the particle size when the cumulative percentage under the sieve is 90%, and Dp10 is the particle size when the cumulative percentage under the sieve is 10%.
In Table 1, the blank is the average particle size and particle size distribution of the used powder itself (epoxy powder was used in this experiment). Further, the graph numbers described in the column of the particle size distribution in Table 1 correspond to the numbers of the particle size distribution graph shown in FIG.

[0031]

[Table 1] As can be seen from Table 1, the higher the collection position, the smaller the average particle size of the particles collected at that position, and it can be seen that the particle size can be selected depending on the collection position. It can also be seen that the higher the collection position, the smaller the SD value. Therefore, it can be seen that if the collection is performed at a higher position, particles having a uniform particle diameter and a small diameter can be collected.

Next, an experiment was conducted on the smoothness of the coated surface. Table 2
Means that the powder of the raw material is supplied as it is to the electrolytic fluidized immersion coating apparatus to perform the coating (in Table 2, the powder used A
Case) and the case where the particles collected at a height of 300 mm by the powder supply device are supplied to the electrolytic fluidized immersion coating device to perform coating (in Table 2, the case of the powder B used). Average of undulation pitch of coating surface, average of undulation amplitude, Wave
This is a comparison of Scan values (values of surface irregularities represented by laser reflection intensity).

[0033]

[Table 2] As can be seen from Table 2, those using the raw material powder
Since the undulation pitch of the coated surface is short (1.5 mm) and the undulation amplitude is large (3.4 μm), it can be seen that the undulation is large at short intervals. On the other hand, when particles collected at a height of 300 mm in the powder feeder are used, the undulation pitch of the coated surface is long (4.1 mm) and the undulation amplitude is small (0.9 μm). It can be seen that the surface is fairly smooth. Thus, it can be seen that the smoothness of the coated surface can be ensured by implementing the powder coating system of the present embodiment.

Next, Table 3 shows the particle size distribution of each device (electrolytic fluidized immersion coating device, powder supply device, pulverizing device) in the powder coating system of this example. In Table 3, "before treatment" refers to the particle size and particle size distribution in each tank before performing the electrolytic fluid immersion coating, and "after treatment" refers to within each vessel after performing the electrolytic fluid immersion coating. Are the particle size and particle size distribution.
Also, the graph number described in the column of particle size distribution in the table,
This corresponds to the number in the particle size distribution graph shown in FIG.

[0035]

[Table 3] As can be seen from Table 3, the average particle size of the powder in the powder supply device is larger after the treatment than before the treatment (before treatment: 47 μm, after treatment: 54 μm). This indicates that particles having a small particle diameter were selectively captured and supplied to the electrolytic fluidized immersion apparatus. On the other hand, the average particle diameter of the particles in the electrolytic fluidized immersion apparatus does not change so much before and after the treatment (before treatment: 26 μm, after treatment: 28 μm)
m). This is because the coarse powder in the powder supply device is pulverized by the pulverization device and returned to the powder supply device, and the finely pulverized particles are supplied again into the electrolytic fluidized immersion device. Indicates that fine powder is being supplied. As described above, the coarse powder remaining in the powder supply device is almost returned to the original particle size distribution by the pulverizing device, and it is understood that the electrolytic fluidized immersion coating device can secure a stable particle size distribution. Therefore, by carrying out the present invention, specific supply of specific particles can be stably performed, and coating quality can be maintained.

[0036]

As described above, according to the present invention,
In the powder supply device, specific particles can be selectively supplied. Also, in a system that performs powder coating using specific particles, the selective supply of specific particles,
The coating can be performed stably, and the coating quality can be maintained.

[Brief description of the drawings]

FIG. 1 is an overall schematic diagram of a powder coating system according to an embodiment of the present invention.

FIG. 2 is a schematic sectional view of a powder supply device according to the embodiment of the present invention.

FIG. 3 is a graph showing a particle size distribution corresponding to Tables 1 and 3.

[Description of Signs] 10 ... Powder supply device 11 ... Powder supply tank 12 ... Perforated plate 13 ... Air ejection nozzle 14 ... Ejector 143 ... Powder suction port 15 ...・ Air cylinder (drive means) 30 ・ ・ ・ Electrolytic fluid immersion coating device (powder coating device) 50 ・ ・ ・ Pulverizer 62 ・ ・ ・ First passage 63 ・ ・ ・ Second passage 71 ・ ・ ・ First On-off valve 72 ... second on-off valve

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4D075 AB08 AB12 AB41 AB55 CA47 DA23 DC13 EA02 4F040 AA13 AB15 CC02 CC05 CC14 DA04 4F042 AA09 AB03 BA06 CA01 CA09 CB03 CB08 CB10 CC03 CC07 CC27 EC02 EC05 4G068 AB22 AC09 AD37 AF02 AF36

Claims (2)

[Claims] 1. A powder supply tank, a perforated plate disposed inside the powder supply tank and dividing the internal space of the powder supply tank into an upper space and a lower space, and introduced into the lower space. Pressurizing means for increasing the pressure in the lower space, and powder suction means having a powder suction port protruding into the upper space,
And a driving means for driving the powder suction port vertically in the upper space. 2. A powder supply tank, a perforated plate disposed inside the powder supply tank and dividing the internal space of the powder supply tank into an upper space and a lower space, and introduced into the lower space. Pressurizing means for increasing the pressure in the lower space, and powder suction means having a powder suction port protruding into the upper space,
A powder supply device comprising: a driving means for driving the powder suction port in a vertical direction in the upper space; a powder coating device connected to the powder suction means via a first passage; A crusher connected to the body suction means via a second passage; a first opening / closing valve interposed in the middle of the first passage; and a second opening / closing valve interposed in the middle of the second passage. A powder coating system comprising: an on-off valve.