JPS597792B2 - Steam blackening furnace - Google Patents

Description

[Detailed description of the invention] This invention continuously coats the iron surface in a water vapor atmosphere.

This invention relates to a steam blackening furnace for blackening treatment. The shadow mask generally used for color cathode ray tubes includes:
A blackening film is formed on the surface of iron to prevent rust, prevent light scattering, and improve heat dissipation. It was common to use a pot-shaped blackening film. By the way, in the blackening treatment that produces black rust on the iron surface, the inside of the furnace is maintained at a specified temperature of about 400°C to 580°C in order to produce only black rust without producing red rust on the workpiece. At the same time, it is necessary to fill the furnace with water vapor so that no air is present in the furnace, and in this case, the thickness of the blackened film is controlled by the temperature inside the furnace and the processing time.

However, when blackening treatment is performed using such a box-shaped or pot-shaped blackening film, a part of it must be opened to take in and out the material to be treated, so when the opening is done, water vapor is released outside the furnace. In addition, the temperature conditions and steam atmosphere must be adjusted for each treatment, making it impossible to continuously flow the material and causing energy loss.

In order to solve these conventional problems, it is also conceivable to use a mountain-shaped heat treatment furnace as the blackening film as described in US Pat. No. 3,185,597.

However, if this conventional furnace is used as it is for blackening film, the excess water vapor introduced into the furnace will be discharged from the entrance and exit of the tunnel, and the temperature at the entrance and exit tends to become low. Therefore, a problem arises in which water vapor condenses. The present invention has been made in order to eliminate such problems, and includes providing a water vapor introduction means in a mountain-shaped tunnel, and further providing a water vapor discharge means at at least one location in the tunnel, and providing the water vapor discharge means with a membrane pressure. By connecting the adjustment means, there is no need to adjust the temperature conditions and steam atmosphere for each treatment, and good blackening treatment can be performed continuously. Moreover, there is no need to adjust the temperature conditions or steam atmosphere for each treatment. The purpose of the present invention is to provide a steam blackening furnace that can prevent this.

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

1 to 3 show an embodiment of the present invention. In FIG. 1, 1 is a mountain-shaped tunnel, 2 is a heater section that heats the tunnel 1, and 3 is an endless-shaped tunnel that runs inside the tunnel 1. A mesh belt, 4 is a roller that drives the mesh belt 3, 5 is a steam generator that generates steam, and 6 is a pipe that discharges the steam generated by the steam generator 5 into the tunnel 1. FIG. 3 is a schematic diagram for explaining the steam discharge means and furnace pressure adjustment means of the apparatus of this embodiment.

In FIG. 3, the same reference numerals as in FIG. 1 indicate the same or corresponding parts, and illustration of the heater section 2, belt 3, roller 4, steam generator 5, and pipe 6 in FIG. 1 is omitted. A discharge pipe 8 is provided at the inclined part of the tunnel 1 as a steam discharge means for discharging surplus steam inside the tunnel 1 to the outside of the tunnel 1, and the tip of the discharge pipe 8 is connected to a water tank serving as a furnace pressure adjustment means. 9 has entered the water. This water tank 9 is used to control the pressure inside the furnace of the steam atmosphere by the height of the water surface.
The discharge pipe 8 also serves to discharge water condensed within the tunnel 1 to the outside of the tunnel 1. In such a configuration, when water vapor is continuously introduced into the tunnel 1 from the pipe 6, the surplus water vapor is discharged outside the tunnel 1 through the exhaust pipe 8, as shown by diagonal lines 7 in FIGS. Due to the density difference between water vapor and air, water vapor flows into tunnel 1.
Only the top of the area will be filled. While maintaining this state, the heater section 2 heats the filled steam atmosphere region to a temperature at which the workpiece will not form red rust but will only form black rust, i.e. approximately 580°C to 400°C.
In addition, the temperature is set at a temperature at which red rust does not form in the part of the tunnel 1 other than the above-mentioned top part, that is, an area that is not filled with water vapor, and at which water vapor attached to the surface of the workpiece does not condense, that is, approximately Set the temperature to 400C to 100C. In such a state, when the objects to be processed, that is, iron, are sequentially placed on the mesh belt 3 and sent into the steam atmosphere at the top of the tunnel 1, the following reaction occurs as the objects pass through the high temperature steam atmosphere, and black Rust, or Fe3O4, continuously forms on the iron surface.

The configuration of this embodiment has the following advantages.

Generally, in a device without a water vapor discharge pipe 8, if water vapor is continuously supplied, excess water vapor will be discharged from the entrance and exit of the tunnel 1, and even in this case, the entire interior of the tunnel 1 will be heated to 580°C to 400°C. If you do this, the water vapor will not condense and there will be no problem in principle. However, the entrance and exit sides of the tunnel 1 tend to be lower in temperature than the top, and therefore it is difficult to avoid condensation of water vapor in these low temperature areas, resulting in stains and other contamination on the surface of the workpiece. There is concern that a blackened film may not be obtained. However, in the device of this embodiment, the discharge pipe 8 is provided as shown in FIG. The whole area is 58 "C ~
There is no need to raise the temperature to 400°C, which is very convenient as it saves energy. In this case, as shown by diagonal lines 10 in FIG. 3, if the atmospheres of water vapor and air are shut off using a non-oxidizing gas such as nitrogen, and the discharge pipe 8 is provided near the contact point between the water vapor and the non-oxidizing gas, Furthermore, stable blackening treatment can be performed.

In the above embodiment, the case where the discharge pipe 8 is provided only on the inlet side has been described, but it is more effective if the discharge pipe 8 is also provided on the outlet side in the same way.

As described above, according to the present invention, since the mountain-shaped tunnel is provided with the steam introduction means, the steam discharge means, and the furnace pressure adjustment means, there is no need to adjust the temperature conditions and steam atmosphere for each treatment, and the process can be continued continuously. It has the advantage of not only being able to perform a good blackening treatment, but also being able to prevent water vapor from condensing in low-temperature areas, as well as being able to use energy effectively, so its practical value is extremely great.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is an explanatory diagram thereof, and FIG. 3 is a schematic diagram showing a steam discharge means and a furnace pressure adjustment means. 1... Tunnel, 2... Heating means (heater), 3, 4... Conveying means (mesh belt, roller), 5, 6... Steam introduction Means (steam generator, pipe), meter...Steam discharge means (discharge pipe), 9...Furnace pressure adjustment means (water tank)
.

Claims (1)

[Claims] 1. A mountain-shaped tunnel, a water vapor introducing means for introducing water vapor into the tunnel, and a water vapor exhausting means provided at at least one location between the entrance and exit of the tunnel and discharging the water vapor inside the tunnel to the outside, Furnace pressure adjusting means connected to the steam discharge means and for maintaining the inside of the tunnel at a predetermined pressure; conveying means that travels within the tunnel and transports the workpiece; A steam blackening furnace characterized in that it is equipped with heating means for maintaining the temperature at a temperature at which only black rust is produced without producing red rust.