JP2933813B2 - Continuous gas carburizing furnace for metal strip - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a continuous gas carburizing furnace for a metal strip, which has a plurality of paths in a carburizing atmosphere chamber.

[0002]

2. Description of the Related Art Conventionally, in the metal secondary processing industry such as the automobile industry, there has been a demand for higher workability and higher strength for a metal plate to be processed. That is,
In the automobile industry, it has been necessary to reduce the weight of the vehicle body in order to pursue low fuel consumption due to global environmental problems that have recently become a problem. Above, there is a need for higher strength thin steel sheets.

[0003] The evaluation index of such a metal plate includes, for example, ductility, deep drawability, aging, strength, secondary work brittleness, and the like.
Baking hardenability, spot weldability, etc. are considered. Therefore,
The present applicant obtains the ductility, deep drawability and aging property by recrystallizing and annealing a metal band made of ultra-low carbon steel by continuous annealing, and subsequently performing continuous carburizing to the surface layer portion. By the presence of solid solution C,
In order to improve the tensile strength, secondary work brittleness resistance, bake hardenability, and spot weldability, Japanese Patent Application Laid-Open No.
No. 88126 has developed a continuous annealing carburizing facility.

According to the continuous annealing carburizing equipment, the heating zone 1
After performing predetermined recrystallization annealing on the metal zone S in the second or soaking zone 13, the temperature of the steel sheet, the atmosphere specifications, and the conveying speed (furnace time) are controlled in the gas carburizing zone 14, and the first cooling zone is performed. By performing appropriate carburizing treatment with controlled cooling conditions in the 15 and the second cooling zone 16, a metal strip having a desired surface carburization depth and concentration distribution is continuously produced while satisfying the specifications of the metal strip. can do.

[0005] In the vertical continuous gas carburizing furnace 1 forming the gas carburizing zone 14 of such a continuous annealing and carburizing equipment, for example, as shown in FIG.
Rolls R _{1 to} R ₃ for direction change are installed in the carburizing atmosphere chamber 11 to form a passing plate path including a plurality of passes.

[0006]

However, as described above, when the direction of a metal strip is changed by a roll installed in a carburizing furnace, the metal strip is passed through in a state of being in contact with the roll. Is attached to the roll, and the scale or the like attached to the roll tends to cause a pick-up phenomenon in which the surface of the metal band is scratched. In addition, in particular, the rolls in the carburizing atmosphere chamber are susceptible to corrosion, and the deficiency of the roll surface due to the corrosion has been a major factor in generating flaws on the metal band surface.

[0007] Further, in the conventional gas carburizing furnace, since the carburizing atmosphere is controlled in the entire carburizing atmosphere chamber in the furnace, it takes time until the entire chamber becomes a desired state.
There has also been a demand for improved responsiveness to control of the carburizing atmosphere of the metal strip. The present invention has been made in view of such problems of the prior art, and has a continuous gas carburizing furnace for a metal strip provided with a passing plate path having a plurality of paths in a carburizing atmosphere chamber. It is another object of the present invention to make the surface of the metal strip less prone to flaws and to improve the responsiveness of controlling the carburizing atmosphere of the metal strip.

[0008]

In order to achieve the above object, a continuous gas carburizing furnace according to the present invention is provided with a metal strip in a carburizing atmosphere chamber controlled to a predetermined carburizing atmosphere and having a plurality of passes through a metal plate. In a continuous gas carburizing furnace for a metal strip, which performs a desired carburizing treatment on the metal strip, the carburizing gas is blown onto the plate surface of the metal strip, whereby the metal strip passes the gas pressure along the plate path. The gas supporting device supported by the above is provided over the entire area of the passageway in the carburized atmosphere chamber.

It is preferable that the gas supporting device is partitioned along the direction of the plate, and that the pressure of the blowing gas can be controlled for each partition.

[0010]

In the continuous gas carburizing furnace according to the present invention, a gas supporting device for supporting the metal strip with the gas pressure along the plate path by spraying the carburizing gas onto the plate surface of the metal strip is provided in the carburizing atmosphere chamber. Since the carburizing gas is directly blown onto the plate surface by providing the entire surface of the sheet path, the response to the control of the carburizing atmosphere of the metal band is improved, and the passing of the metal band is performed in a non-contact state in the carburizing atmosphere chamber. Therefore, a flaw caused by the pick-up phenomenon or a roll surface defect unlike the case where the roll is performed in a contact state hardly occurs.

Further, if the gas supporting device is divided along the plate passing direction and the pressure of the gas to be blown can be controlled for each section, the gas blowing pressure can be changed for each section and the like, so that the gas supporting device can be controlled in accordance with the position of the gas passing. It becomes possible to control the supporting force.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing a continuous gas carburizing furnace in this embodiment. As can be seen from this figure, this carburizing furnace 1
Corresponds to the gas carburizing zone 14 in the above-mentioned continuous annealing carburizing equipment (FIG. 3), and the roll chamber 2 in which the feed rolls R ₁ and R ₂ are disposed is sectioned downward by the sealing device 3 to form a seal. Above the device 3, a carburizing atmosphere chamber 11 is maintained at a predetermined carburizing atmosphere. Then, the metal zone S subjected to the predetermined recrystallization annealing in the heating zone 12 and the soaking zone 13 in FIG. 3 is fed into the carburizing atmosphere chamber 11 by the feed roll R ₁ of the roll chamber 2, and in after performing predetermined continuous gas carburizing to the metal strip S, the first cooling zone in FIG. 3 by the roll R ₂ sends the metal strip S 1
I am aiming for 5.

A feed roll R ₁ is provided in the carburizing atmosphere chamber 11.
In order to form a threading path that lowers the metal strip S fed in the ascending state at the upper part, raises it again at the lower part, and further lowers it at the upper part, without installing a turning roll, The gas support devices 4 and 5 were installed inside and outside the passing plateway over the entire area of the road. This gas support device 4,
Numeral 5 is for supporting the metal band S by gas pressure along the plate path by spraying a carburizing gas onto the plate surface of the metal band S. As shown in FIG. 2, the metal band S is formed in a width corresponding to the plate width. The main bodies 41 and 51 are installed along the entire board path, and
Guide surfaces 41a and 51a are formed on the plate surface sides of the metal strips S and 51 along the passageway. That is, the guide surface corresponding to the direction change position of the metal band S is formed in an arc shape, and the other guide surfaces corresponding to the ascending and descending positions are formed in a planar shape.

As shown in FIG. 2, inside the main body 41 of the gas support device 4, there are provided gas supply chambers 42a, 42b,.
a, 42b,... are provided with an air supply pipe 43a for introducing a carburizing gas.
43b are connected to each other, and a number of gas outlets 44 are provided in a member forming the guide surface 41a of the main body 41. Although not shown, each chamber 4
A mechanism for blowing the gas inside 2a, 42b,... From the gas outlet 44 toward the plate surface of the metal strip S;
a, 42b,... and a control device for controlling the gas pressure, the composition of the introduced gas and the gas temperature for each chamber. The outer gas supporting device 5 has the same structure.

The gas pressure in the chamber is determined, for example, by the pressure of the gas blown out from the gas blowout port.
Is controlled in each chamber such that the metal strip S is maintained in a predetermined shape along the plate path, and a desired tension is applied without causing the metal strip S to loosen. Therefore, in the metal strip S fed into the carburizing furnace 1, a carburizing gas whose composition and temperature are controlled in accordance with carburizing conditions is applied to the metal sheet S at a predetermined pressure toward the sheet surfaces on both sides over the entire sheet passing path. Is blown from the gas outlet of each chamber. Thus, the metal strip S is placed in the carburizing atmosphere chamber 1
Since the carburizing is performed while moving in a predetermined passing path in a non-contact manner in the inside of 1, the surface is hardly flawed during the passing. In addition, since the carburizing gas is blown directly to the plate surface, the responsiveness of the metal strip S to the control of the carburizing atmosphere is improved.

[0016]

As described above, according to the continuous gas carburizing furnace for a metal strip in the present invention, the gas supporting device is provided over the entire passageway in the carburizing atmosphere chamber.
Flaws are less likely to occur on the surface of the metal strip during passing, and the response of the metal strip to carburizing atmosphere control is also improved.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a continuous gas carburizing furnace according to one embodiment of the present invention.

FIG. 2 is a partially enlarged view of FIG.

FIG. 3 is a schematic configuration diagram showing a continuous annealing carburizing facility to which the carburizing furnace of FIG. 1 can be applied.

FIG. 4 is a schematic view showing an example of a conventional continuous gas carburizing furnace.

[Explanation of symbols]

 Reference Signs List 1 continuous gas carburizing furnace 11 carburizing atmosphere chamber 4 gas supporting device 5 gas supporting device S metal strip

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Noriaki Hanazono 1-chome, Mizushima-Kawasaki-dori, Kurashiki-shi, Okayama Pref. Kawasaki Steel Corporation Mizushima Works (56) References JP-A-6-158180 (JP, A (58) Fields surveyed (Int. Cl. ⁶ , DB name) C23C 8/20-8/32

Claims (2)

(57) [Claims] 1. A continuous gas of a metal strip that passes a metal strip through a passage having a plurality of paths in a carburizing atmosphere chamber controlled to a predetermined carburizing atmosphere and performs a desired carburizing process on the metal strip. In the carburizing furnace, a gas supporting device that supports the metal band at a gas pressure along the plate path by spraying a carburizing gas onto a plate surface of the metal band is provided throughout the entire plate path in the carburizing atmosphere chamber. A continuous gas carburizing furnace for metal strips. 2. The continuous gas carburizing furnace for a metal strip according to claim 1, wherein the gas supporting device is partitioned along the direction of the plate, and the pressure of the blowing gas can be controlled for each partition.