JPS61201787A - Electrostatic enameling method with enamel powder - Google Patents

Abstract

PURPOSE:To enamel electrostatically the inside of a nearly hermetically sealed vessel by putting a gun for electrostatic enameling in the vessel, carrying out enameling, introducing dry air into the vessel, and exhausting it. CONSTITUTION:A conveyor 14 suspending a nearly hermetically sealed can 1 is stopped at a work position, and a gun 15 for electrostatic enameling is moved upward and put in the can 1 from the inlet 10. While the can 1 is rotated with a pair of rotating devices 20 attached to walls 19 on both sides of the can 1, the gun 15 is vertically moved with a vertical moving device 18 to enamel uniformly the inside of the can 1. After the gun 15 is taken out, the can 1 is conveyed to the next work position with the conveyor 14. At the work position, a dry air feed pipe is connected to one end of the can 1, an exhaust pipe to the other end, and the inside of the can 1 is dried by feeding dry air into the can 1 from the feed pipe and exhausting it from the exhaust pipe.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a method for applying enamel glaze to prevent corrosion on the inner surface of a container whose outer periphery is almost sealed, that is, an electric water heater or a hot water storage tank. The present invention relates to a method using an enamel powder electrostatic glazing method as the glazing method.

[Background of the invention]

The method of applying enamel to the inner surface of the can body of electric water heaters, hot water tanks, hot water boilers, etc. for corrosion prevention is the wet method, in which the raw material (frit) of enamel is coated with water and applied to the can body. is used a lot.

On the other hand, the powder electrostatic glazing method uses the same principle and system as powder electrostatic coating in the painting industry, and uses inorganic frit powder (hereinafter referred to as glaze) instead of resin powder.
It is used to apply the coating.

This enamel powder electrostatic glazing method is described in "Metal Surface Technology" Volume 28, No. 7 (published in 1977), pages 2 to 9.
Part 8 of ``Flowing Powder Dry Electrostatic Glazing'' and ``Real A Surface Technology''
Details are given in the literature entitled "Powder Enamel Coating Lines in Europe" on pages 23 to 32 of Volume 1, No. 8 (1981).

The glaze can be applied only once and then fired, or the bottom glaze can be applied thinly and then the top glaze can be applied thickly.

In other words, after applying it twice, it is fired.

2-burner area - (To explain Ic, it is intended to glaze the upper panels of cooking tables, gas ranges, sinks, etc.) The objects to be glazed are hung on a conveyor, and first the lower glaze is applied. Place it in the booth and apply the underglaze using several cans set up on the left and right in the transport direction.

Next, the pieces enter the top glaze booth and apply the top glaze using a plurality of cans installed on the left and right sides of the conveyance direction. Then, it is sent to a kiln.

A device for recovering the glaze components that were not applied is installed at the bottom of the bottom and top glaze booths. This device consists of a filter belt that rotates horizontally at the bottom of the booth, an exhaust fan connected to the filter belt, and a recovery device for recovering the glaze remaining on the filter belt.

The unapplied glaze falls, and since the inside of the filter belt is under negative pressure with an exhaust fan, these ash-containing glazes remain on the upper surface of the filter belt. Since this filter belt is rotating, the glaze is collected by a recovery device.
Ru.

This collection device consists of a suction head provided near the top of the filter belt, a collection machine, and a second exhaust fan,
They are connected in series.

The glaze on the filter belt is sucked up by a suction head similar to a vacuum cleaner and sent to a collection machine. This recovery machine consists of a filter and a recovery tank, and the glaze is recovered. This glaze will be reused.

The booth is equipped with an air conditioner.

The glazed object of t18 is like wood.

Furthermore, since the filter belt opens into the booth, the space for the exhaust fan that creates a negative pressure inside the filter belt must be large and expensive.

[Purpose of the invention]

An object of the present invention is to glaze the inside of a container whose outer periphery is almost sealed, ie, the inside of a can such as an electric water heater, using an electrostatic glazing method.

[Summary of the invention]

The methods of electrostatic glazing that have been put into practical use are:
The glazed object is plate-shaped, with a large glazed surface open to the atmosphere. With such a shape, the ash-like glaze and the floating ultrafine particles of the glaze will be sucked out by the exhaust fan, so they will not cause any defects.

However, the body of an electric water heater or the like consists of a cylindrical body plate, an upper end plate, and a lower end plate, which are welded together. In the case of products that apply glaze to the inside of a can that is integrally constructed by welding, even if the lower part of the booth is suctioned, the inside of the can cannot be suctioned strongly, so the ash-like glaze accumulates at the bottom of the can, and The ultrafine glaze remains suspended inside the can. If these glazes remain, the thickness of the enamel at the bottom of the can becomes thick or electrostatic repulsion occurs, resulting in enamel defects. It also interferes with the coating during the primary glazing process.

In the present invention, glazing is carried out with an electrostatic glazing can facing inside a container whose outer periphery is mostly closed, and then a drying air supply pipe is connected to one end of the container and an exhaust pipe is connected to the other end. It is connected to scavenge air.

[Embodiments of the invention]

Hereinafter, the present invention will be explained with reference to an embodiment shown in FIG.

The shape of the glazed electric water heater can will be explained with reference to Fig. 2. The can j consists of a cylindrical body plate 2, an upper head plate 3, and a lower head plate 4, which are integrally welded together. A water supply pipe 5 and a skin heater mounting seat 6 are provided on the side surface of the lower mirror plate 4. A hot water outlet pipe 7 is provided on the upper surface of the lower mirror plate 3.

8 is a leg, and 9 is a hanging seat. The configuration up to this point is the same as before.

The lower surface of the lower mirror plate 3 has an insertion opening for a can for glazing. This insertion opening 10 is provided with a flange 1, and is closed with a lid after firing.

In the glazing process described later, the water supply pipe 5 & heater mounting seat 6
Attach the stopper and close it.

The glazing method will be explained based on Fig. 1 etc. Can bodies are hung on a conveyor while being transported through the booth? This is glazed. For this reason, work in each process is performed sequentially along the conveyor. In addition, the conveyor operates intermittently and stops during work in one process, and when one work is completed, the conveyor starts and moves to the work position I of the next process.
It will continue to feed up to ii and stop there.

The glazing method shown in FIG. 1 involves applying top glaze once, applying top glaze twice, and then firing.

! J] In the figure, first, the top glaze is applied.

As shown in FIG. 3, when the conveyor 14 suspending the can body 1 stops at this working position, the electrostatic glazing can 5 is raised and inserted through the insertion opening 10, and while the can 15 is operated, 15 up and down. This glazing operation is carried out, for example, by electrostatic force and a jet of dry air. The vertical movement of the can 15 is performed by a vertical movement device 18# provided at the bottom of the booth 16.

Also, rotate the can and rub it to ensure that the glaze is applied evenly. As shown in FIGS. 3 and 4, the can body 1 is rotated by a pair of rotating devices 20 and 20 IC provided on both side walls 19 of the booth 16. The rotating device 20 is movable toward the center and has a plurality of rollers 21 in contact with the can body 1 on the tip side, at least one of which is rotated by a drive source so as to rotate the can body 1. . gJ4
In the figure, the direction of the arrow is the direction in which the can body 1 is conveyed by the conveyor, and the rotating device 120 can convey the can body 1 and move backward as shown in the figure. Note that the hanger 23 of the conveyor 14 is rotatably attached.

When the work of applying the top glaze is completed, the can 5 is taken out, the rotating device 20 is moved backward, and the conveyor is driven to transport the can body 1 to the position where the next work is to be performed.

Then stop.

Next, air blower work and static electricity removal work inside the can body 1 will be performed.

As shown in FIG.
# Connect the dry baking air supply pipe 25 and insert the lower insertion port] 0
An exhaust pipe 26 is connected to the exhaust pipe 26, and dry air is supplied at a low speed from the supply pipe 25, and is sucked and discharged through the exhaust pipe 25. Is the blowing speed of dry air from the supply pipe 25 normal? The speed is slow enough to prevent the glaze from being blown off. The exhaust pipe 26i is provided with an exhaust fan and a filter.

As a result, the inside of the can body 1 is purged, and the glaze accumulated in the lower part and the ultrafine glaze particles floating inside the can body 1 can be removed.

Since the accumulated glaze can be discharged, the film thickness at the bottom is too thick.
You can prevent this from happening. Accumulated glaze particles tend to cause radial defects due to electrostatic repulsion between each other, but this
, can be prevented. In addition, if the glazing operation is performed in the next step with ultrafine particles that did not adhere due to poor charging properties floating in the can body 1, the floating glaze and normal glaze will collide. As a result, the coating performance is greatly reduced, but
This can be prevented.

In this way, unnecessary glaze is discharged in a closed system in which a supply pipe is connected to one side of the can body and an exhaust pipe is connected to the other side. Therefore, the supply fan and suction fan can be made smaller. Moreover, the air conditioning equipment for supplying dry air can also be made smaller.

Of course, the inside of the booth 16 is also air-conditioned to prevent the influence of air during transportation inside the booth 16, but this does not require much management and capacity.

The exhaust pipe 26 is raised and lowered by a vertical motion gtlt 27 provided at the lower part I7 of the booth 16. An elastic body is disposed between the tip of the exhaust pipe 26 and the tip of the vertical movement device 27.

28 is a bellows pipe of an exhaust pipe.

The supply pipe 25 is projected from the center side by a lateral moving device 30 installed on the side 1118c of the booth 6.
It is moved up and down by a vertical movement device 31 installed at 0. 32
is a bellows tube for supply. The tip of the supply pipe 25 is the exhaust pipe 2
Similarly to 6, an elastic body is provided.

When connecting the supply pipe 25 to the outlet pipe 7, the can body is supported by a rotating device 20 as shown in FIGS. 3 and 4, and the can body is rotated and positioned. You can consider rubbing it once to avoid hitting the hanger 23C. Also, when moving from the glazing process position to the air blowing process position, t
If you do not rotate this, use the rotation 5 & position to determine the position at the glazing process position.

In addition to the above-mentioned air blower work, the static electricity eliminator 35 is used to remove the static electricity accumulated in the can. This reduces residual static electricity and improves the adhesion during glazing in the primary step.

Since it is carried out along with the air processing work, efficiency can be improved.

The electrostatic repulsion +135 is installed on the side wall 19tC of the booth 16, and can move forward and backward with respect to the center, and its grounded brush 36 is brought into contact with the can body 1 and moved so as to rub it.

Since the contact surface of the brush 36 is the outer surface of the can body 1, it does not affect the coating surface.

Is the coating efficiency over 90% when using air blow and static removal work together? Again with this improvement.

When the air blowing work and the static electricity removal work are completed, the conveyor 4 is started, and the top glaze is sent to the first glazing position to perform the glazing work. This working device is the same as that for underglaze, and performs the same work.

Next, carry out the air blower work and static electricity removal work, and perform the same work using the same work equipment as in section g.

Next, the top glaze is sent to the second glazing position, and the same operation is carried out using the same equipment as above.

Next, send it to the air blower work position and perform the same work using the same device as in Section M. However, static electricity removal work will not be performed.

Next, it is sent to a firing furnace and fired.

As is clear from the above description, the glazing work positions are installed in series in the booth.

In air blowing, it is also possible to supply air from below and exhaust it from above.

It can also be used for one-time use.

Other static electricity eliminators may be used. For example, it is conceivable to adopt a static electricity eliminator equipped with an air set used in the assembly work of electronic parts.

〔Effect of the invention〕

In the present invention, when glazing the inside of a sealed container, the glaze is applied with the can facing inside, and then a dry air supply pipe is installed at one end of the container and an exhaust pipe is installed at the other end. Since it is connected and scavenged, it is possible to electrostatically enamel almost any closed container, and it is possible to obtain enamel with fewer defects.

[Brief explanation of the drawing]

FIG. 1 is a process diagram of a glazing method according to an embodiment of the present invention. FIG. 2 is a longitudinal cross-sectional view of the can of the electric water heater used in the present invention;
Figure 3 is a longitudinal cross-sectional view during the glazing process, Figure 4 is a plan view of the rotating device for the can body, and Figure 5 is a front view of the air blower operation and static electricity removal operation. ,7...
... Hot water pipe, ]O ... Insertion port, 14 ...
... Conveyor, 15 ... Electrostatic glazing can, 1
6...Booth, 20...Rotating device, 2
1... Roller, 25... Dry air supply pipe, 26... Exhaust 10 liters, Fig. 30

Claims (1)

[Claims] 1. Glaze is applied with an electrostatic glazing can facing inside a container whose outer periphery is mostly closed, and then a dry air supply pipe is placed on one end of the container, and a dry air supply pipe is placed on the other end An enamel powder electrostatic glazing method characterized by connecting an exhaust pipe to the enamel powder and scavenging the air.