JPS6021321A - Heating or cooling method of metallic object by fluidized bed furnace - Google Patents

Abstract

PURPOSE:To reduce the time for treatment in the stage of heating or cooling a metallic object in a fluidized bed furnace by moving vertically said object back and forth in the fluidized bed. CONSTITUTION:A gas diffuser 5 constituting of a pressure chamber 3 and a treating chamber 4 is provided in a retort 2. A pressurized fluidizing gas is introduced into the chamber 3 and is dispersed so as to be admitted into the chamber 4 in which a refractory fluidizing medium is packed, thereby forming a fluidized bed. The fluidized bed is maintained by an electric heater 7 at the temp. at which a heating or cooling treatment is accomplished. A metallic object 1 suspended from the hook 10 of a rack 9 provided to a rack and pinion mechanism 8 is dipped in the fluidized bed. A pinion 11 is driven to rotate forward and backward at a prescribed cycle, by which the object 1 is vertically moved back and forth and is treated. The treating speed is thus increased and the time for the treatment is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for heating or cooling metal objects using a fluidized bed furnace.

Fluidized bed furnaces have various superior properties compared to other furnaces, such as better thermal conductivity to the workpiece, easier temperature control, and more uniform temperature distribution.

However, when using this furnace to heat or cool metal objects such as shafts, the heating rate or cooling rate is much faster than that of an atmospheric furnace, but the rate of heating or cooling is much faster than that of an atmospheric furnace. It had the disadvantage of being a little slow compared to that. For this reason, a longer treatment time was required than in the case of treatment using a salt bath furnace or a lead bath furnace. Particularly when used for cooling treatment such as hardening, there is a drawback that the types of steel that can be treated are limited.

The present invention was developed as a result of intensive studies from various aspects in order to solve these drawbacks, and instead of immersing metal objects in a stationary state in a fluidized bed as in the conventional method, the metal objects are made to move up and down in a fluidized bed. They discovered that the above-mentioned drawbacks can be overcome by processing the material.

That is, the method of heating or cooling a metal object using a fluidized bed furnace according to the present invention is characterized in that the metal object is treated while being reciprocated up and down in a fluidized bed.

The following will be described in more detail based on nine drawings.

In FIG. 1, (1) Ii heat treatment or cooling heat J! 1
It is a metal object that carries out pressure chamber (3).
) and a processing chamber (4).
). From the pipe (6) to the pressure chamber (3)
The pressurized fluidizing gas supplied to the chamber is uniformly dispersed by the gas dispersion device (5) and flows into the processing chamber (4). The flowing medium is fluidized to form a fluidized bed.

Then, in line IIJ1, the fluidized bed is maintained at a temperature at which the fluidized bed is heated or cooled by an electric heater (7). In the treatment, when the fluidized bed becomes stable and the temperature reaches the set temperature, the metal object (1) to be heated or cooled is immersed in the fluidized bed.

In the present invention, when processing in this way, the flow rate is
The metal object (1) immersed in the IJ layer is not kept completely still but is constantly moved up and down and processed in the fluidized bed for a predetermined period of time.

The vertical reciprocating motion of the metal object (1) is, for example, a rank (9) of a rack and pinion mechanism (8) provided above the furnace.
) for suspending the metal object (1) (this can be done by, for example, locking the upper end of the IG and driving the binion (11) in forward and reverse rotation in a predetermined cycle, but is not limited to this) Other known methods may also be used.

To take the metal object (1) out of the furnace after it has been heated or cooled for a specified period of 90 minutes, move it to the hanging tool Q (1-ceiling hoist I) that is locked to the rank (9). It can be carried out by various other well-known methods.

By processing the metal object while moving the entire vertical column 02, the heating rate or cooling rate of the metal object can be further increased, the processing time can be shortened, and the range of application of the furnace can be expanded. The reason why the heating or cooling rate can be further amplified when processing metal objects while moving them back and forth, compared to when processing them while keeping them completely still or rotating them, is because of the flow rate. This is thought to be based on the fact that the relative relationship between the rise and fall of the old metal object in the East J medium causes the fluid medium to come into stronger contact with the metal object, thereby increasing the heat conduction between the two.

Table 1 shows comparative examples and examples in which a steel bar (S45C) with a diameter of 30 mm and a length of 1100 yx is heated to 950'C. In addition, in these comparative examples and examples,
A retort (2) with an inner diameter of 350 mm is filled with 100 meshes of alumina, and 65N of nitrogen gas is supplied from the pipe (6).
1 minute to form a fluidized bed with a height h) of 600 mm, and heated to 950'C±5 with an electric heater (7).
It was held at c.

Table 1 From the above, it is clear that the heat treatment time can be further shortened by vertically reciprocating motion.

Next, in Table 2, a rod wI (8450
) 900°C to 250°C when cooled to 200°C
Cooling time in °C-t is shown.

In addition, in these comparative examples and examples, 80 mm of zircon sand was filled into the inner diameter of 400 mm (19 mm), and air was supplied from the pipe (6) to 19 ONf.
A flow ladle with a height of h) or 750 M was formed by supplying water at a rate of i/min and maintained at 200°C±5°C with an electric heater (7).

From this, it can be seen that even in the case of cooling processing, the processing time can be further shortened by vertically reciprocating motion.

The cooling rate diagram in this case is shown in FIG. 2.

Since a higher cooling rate can be obtained by vertically reciprocating in this manner, the processing time can be shortened.

In addition to the various comparative examples mentioned above, we also inspected ('/1.I K) when reciprocating a metal object in the horizontal direction.
This case was almost the same as Comparative Example (E).

In the present invention, the metal object is not limited to a rod-shaped body, but can be provided in various shapes such as a plate-shaped body, and it is preferable that the speed of the up-and-down reciprocating i1νJ is approximately 3 times the superficial gas velocity.

Note that when immersing metal objects into the fluidized bed, multiple metal objects may be housed in a basket body or the like instead of being immersed one by one. process while

As described above, according to the present invention, a method of heating or cooling a metal object using a fluidized bed, which can shorten the processing time, can be obtained.゛

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the manner in which metal objects are heated or cooled by a fluidized bed furnace, and FIG. 2 is a cooling rate line 1-1. (1), metal object, (2) shi1・/l/1・, (31:
pressure chamber. (4): Processing chamber, (5) Gas dispersion device. (6): Pipe line for supplying fluidizing gas.

Claims (1)

[Claims] (1) A method for heating or cooling a metal object using a fluidized bed furnace, characterized in that the metal object is treated while being reciprocated up and down in a fluidized bed.