JPH0741867A - Batch type heat treatment apparatus for improving descaling property - Google Patents

Abstract

PURPOSE:To prevent a batch type heat treatment apparatus, in which the heat treatment is executed to a treated material of wire rod, etc., wound in the coil state and descaling property is improved to easily detach the scale produced on the surface. CONSTITUTION:The apparatus is composed of heating chambers 1a, 1b, 1c, in which the air is introduced to produce the thick scale on the surface of the treated material 6 after executing heating, soaking and the prescribed heat treatment to the treated material 6 by charging the treated material 6 of the wire rod, etc., in the chamber kept to reducing atmosphere, and a cooling chamber 13, in which the treated material 6 taken out from the heating chambers 1a, 1b, 1c is rapidly cooled with air blast.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a batch-type heat treatment apparatus for heat-treating a treated steel material such as a wire wound in a coil shape and improving so that scales generated on the surface of the steel material can be easily removed. .

[0002]

2. Description of the Related Art When a steel material such as a bar material, a wire coil or the like which has been heat-pressed is further subjected to high-dimensional plastic working such as wire drawing or cold forging, the steel material is subjected to a predetermined atmosphere in a reducing atmosphere prior to the working. It is annealed by heating, soaking, and slow cooling in the process.

Scales are generated on the surface of the steel material after the heat treatment, and if the above-mentioned processing is performed with the scales adhered, the dies may be significantly worn or the scales may be hard to get into the ground, thus deteriorating the quality. The steel material after heat treatment is descaled by a chemical method such as pickling or a mechanical method such as shot blasting.

[0004]

When the steel material is taken out from the atmospheric heat treatment furnace at about 650 ° C. and left in the atmosphere, wustite (F _e O) is generated on the surface of the steel material, and the wustite is magnetite (F _{e 3} O ₄ ), hematite (F
_e2 O ₃ ). Therefore, on the surface of the steel material, a wustite layer, a magnetite layer,
A scale consisting of a hematite layer is formed.

When cooled slowly, a part of the wustite layer near the base steel interface transforms into magnetite and iron. When gradually cooled in the atmosphere in this way, hard magnetite precipitates with wustite on the surface of the steel material and the magnetite does not easily dissolve even by pickling, and it does not easily fall off even by a mechanical method such as shot blasting. The descaling property becomes extremely poor.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and an object of the present invention is to provide a batch type heat treatment apparatus in which descaling of steel materials is further improved. Therefore, the present invention provides a heating chamber in which a treated product such as a wire is charged into a chamber kept in a reducing atmosphere, and the treated product is heated, soaked and subjected to a predetermined heat treatment, and a surface of the treated product. It is characterized by comprising a means for oxidizing and a cooling chamber for rapidly cooling the treated product whose surface is oxidized. Further, the present invention provides a heating chamber in which a treated product such as a wire is charged into a chamber kept in a reducing atmosphere to heat and soak the treated product to perform a predetermined heat treatment, and an oxidizing gas in the heating chamber. And a cooling chamber for rapidly cooling the processed product taken out from the heating chamber. Further, according to the present invention, a treated room such as a wire rod is charged into a chamber kept in a reducing atmosphere, and the treated room is heated, soaked and subjected to a predetermined heat treatment, and a heating chamber taken out from the heating chamber. It is characterized in that it comprises a cooling chamber for rapidly cooling the processed product, and an oxidizing gas is introduced into the chamber of the cooling chamber. Furthermore, in the present invention, the temperature of the processed product in the heating chamber is set to 700 to 5
The feature was that air was introduced at 60 ° C. Furthermore, the present invention provides at least 56 processed products in the cooling chamber.
It is characterized by cooling in the range of 0 ° C to 350 ° C at a cooling rate of 8 ° C / min or more.

[0007]

The steel material taken out from the heating chamber is rapidly cooled to form a scale with many cracks, thereby facilitating the permeation of the acid solution and improving the descaling property. Also,
By accelerating the oxidation of the surface of the treated product, the magnetite layer occupies the majority, and a scale with a thin wustite layer is formed at the interface of the ground iron. And this scale is 8 ℃
Many cracks are generated by rapid cooling of more than 1 minute. For this reason, the dense and thick magnetite layer easily holds the thin wustite layer and peels it off, and facilitates descaling by a mechanical method. Furthermore, the promotion of oxidation of the surface of the treated product is 560
Perform at a temperature of ℃ or above.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a plan view of the entire batch type heat treatment apparatus. In the figure, 1a, 1b and 1c are heating chambers provided adjacent to each other, and the heating chambers 1a, 1b and 1c are constructed by heat insulating walls as shown in FIG.
Is provided. 3 is a conveying roller provided in series on the floor surface, 4 is a ceiling fan, 5 is a radiant tube burner type heater, and 6 is a wire rod coil which is a processed product loaded in the room. A gas generator 7 for supplying a reducing atmosphere gas to each heating chamber 1a, 1b, 1c,
Blowers 8 are respectively connected via valves for introducing air.

Reference numeral 9 denotes a transfer carriage provided on a rail 10 so as to be able to traverse in front of the heating chambers 1a, 1b, 1c, and on the transfer carriage 9 at the same level as that of the conveying rollers 3. A continuous transfer roller 11 is provided so that the processed product 6 loaded or unloaded from the heating chambers 1a, 1b, 1c is supported on the transfer roller 11 in a transportable manner.

Numeral 13 is a heating chamber 1a, 1 separated by a rail 10.
In the cooling chamber provided on the side opposite to b and 1c, the cooling chamber 13
As shown in FIG. 4, fans 14, 15 and 16 for blowing outside air are provided on the hearth and both side walls, respectively, and the cooling chamber 13
The treated product 6 can be rapidly cooled at a rate of 8 ° C./min or more by applying an external air blast to the lower surface of the treated product 6 and its surroundings. Reference numeral 17 denotes an exhaust port provided on the ceiling of the cooling chamber 13, 18 denotes a conveying roller provided on the floor of the cooling chamber 13, and 19 denotes an entrance / exit door provided at one end of the cooling chamber 13.

In this heat treatment apparatus, three heating chambers 1a,
The usage cycles of 1b and 1c will be slightly shifted from each other. That is, first, the door 2 of the heating chamber 1a is opened to stop the transport carriage 9 in front of it, and the processed product 6 supported on the transport carriage 9 is loaded into the heating chamber 1a by driving the transport roller 11 and the transport roller 3. Then, the door 2 is closed, an atmospheric gas is supplied from the gas generator 7 into the heating chamber 1a, and the heater 5 heats and soaks the processed product 6 to a required temperature based on the atmospheric gas. Next, the treated product 6 is loaded into the heating chamber 1b after a short time, and the treated product 6 is loaded into the heating chamber 1c after a short time, and each is heated and soaked to the required temperature.

In this way, when the predetermined heat treatment is completed for the processed product 6 in the heating chamber 1a, the temperature of the heated chamber 1a is not decarburized and magnetite is not formed at the interface of the base metal (processed product 6). 700 ℃ or less at the temperature near the surface of
The temperature is maintained at 560 ° C. or higher) and air is introduced from the blower 8. As a result, the surface of the treated product 6 is oxidized to form a scale of wustite, magnetite and hematite having a thickness of 5 to 20 μm. The temperature near the surface is the temperature of the portion including the scale on the surface of the processed product. In addition, the above temperature range varies depending on the steel grade, but it is expected to be 7
A temperature range of 00 to 560 ° C. is preferable.

This oxidation is also carried out to re-oxidize a part of the scale reduced in the heating chamber 1a and to burn carbon adhering to the soot in the furnace. To generate.

When a thick scale is formed on the surface in this manner, the processed product 6 is placed on the transfer carriage 9 again to cool the chamber 1.
Charge in 3. Then, the fans 14, 15 and 16 apply a blast to the surface of the processed product 6 to rapidly cool the processed product 6, thereby causing a large number of cracks in the scale. This quenching is performed in a temperature range of at least the magnetite formation start temperature at the base steel interface to the transformation end temperature of the wustite formed at the base iron interface (560 depending on the steel type.
(C-300 ° C range). When this temperature range is gradually cooled, the wustite at the base metal interface is transformed into magnetite and the descaling property deteriorates significantly.

The cooling rate varies depending on the steel type, but is 8 ° C /
It is possible to achieve such a cooling rate by providing a fan so as to surround the treated product 6 from both sides and from below in this cooling chamber 13 and blowing its wind directly to the surface. I am trying.

The cooling time is 30 to 40 minutes, whereas the heat treatment time in the heating chambers 1a, 1b and 1c is 15 to 20 hours. By allowing the processed products 6 to be sequentially taken out from 1c, all the processed products 6 can be cooled by the single cooling chamber 13.

The cooling atmosphere is not particularly limited and may be air, N _{2 or} a reducing atmosphere. As the cooling means, other cooling means, for example, spraying of spray water, immersion in a cooling water tank, or the like may be adopted.

In this way, the treated product in which many cracks are contained in the scale due to the rapid cooling can be cleaned easily by mechanical descaling means such as shot blasting, roll bending, air blasting or pickling to make the surface clean. It is possible to significantly improve the sex.

In this embodiment, the heating chambers 1a, 1b,
Although the processed product 6 is oxidized in 1c, the oxidation may be performed by extracting it to the transfer carriage 9 or after charging it in the cooling chamber 13. Alternatively, an independent oxidation chamber may be provided to carry out.

[0020]

As described above, according to the batch type heat treatment apparatus of the present invention, the descaling property of the treated product is remarkably improved, and the scale can be removed more completely by pickling or mechanical method, and the product quality is improved. There is a beneficial effect.

[Brief description of drawings]

FIG. 1 is a plan view showing the entire batch-type heat treatment apparatus for improving the descaling property according to the present invention.

FIG. 2 is a front view of FIG.

FIG. 3 is an enlarged vertical sectional view of the heating chamber of FIG.

4 is an enlarged cross-sectional view of the cooling chamber of FIG.

[Explanation of reference symbols] 1a, 1b, 1c heating chamber 6 treated product 9 transfer carriage 13 cooling chamber 14, 15, 16 fan

Claims (5)

[Claims] 1. A heating chamber in which a treated product such as a wire is charged into a chamber kept in a reducing atmosphere to heat and soak the treated product to perform a predetermined heat treatment, and a surface of the treated product is oxidized. A batch-type heat treatment apparatus for improving descaling property, which comprises a means and a cooling chamber for rapidly cooling a processed product whose surface is oxidized. 2. A heating chamber in which a treated product such as a wire is charged into a chamber kept in a reducing atmosphere to heat and soak the treated product to perform a predetermined heat treatment, and an oxidizing gas is supplied to the heating chamber. A batch type heat treatment apparatus for improving descaling property, which comprises a means for introducing and oxidizing the surface of a treated product and a cooling chamber for rapidly cooling the treated product taken out from the heating chamber. 3. A heating chamber in which a treated product such as a wire is loaded into a chamber kept in a reducing atmosphere to heat and soak the treated product to perform a predetermined heat treatment, and a treatment taken out from the heating chamber. A batch type heat treatment apparatus for improving descaling property, which comprises a cooling chamber for rapidly cooling an article, and an oxidizing gas is introduced into the cooling chamber. 4. The temperature of the processed product in the heating chamber is 700 to 560.
The batch type heat treatment apparatus according to claim 2, wherein the temperature is kept at 0 ° C. and air is introduced. 5. At least 56 processed products in the cooling chamber.
The batch type heat treatment apparatus for improving the descaling property according to any one of claims 1 to 4, wherein the range of 0 ° C to 350 ° C is cooled at a cooling rate of 8 ° C / minute or more.