JPS6075526A - Process for heating wire rod - Google Patents

Abstract

PURPOSE:To save energy consumption in a process for heating wire rod by passing the wire rod on a refractory floor of a heating furnace by heating the wire rod in the same atmosphere as nonoxidizing atmosphere without using reducing atmosphere. CONSTITUTION:A heating furnace 1 is constructed of a preheating zone 2 provided with an air feeding section 3 in its ceiling section performing complete combustion, a heating zone 4 provided with a high-speed burner 5 on the ceiling part inclining toward the preheating zone side 2, and a soaking zone 6 provided with a burner 7 on the side wall of the furnace. Wire rod is fed from a feeding port 8 and burners 5, 7 are operated. The high-speed burner 5 is actuated with <=1 air- fuel ratio, and the gas generated by the combustion is ejected toward the furnace floor to form layer S of nonoxidizing atmosphere on the surface of the furnace floor. The wire rod is heated quickly by the impingement of combustion gas flame from the high-speed burner 5 and direct heat transmission from the furnace floor.

Description

[Detailed description of the invention] The present invention relates to a method for heating a wire.

Conventionally, when heating wire rods made of carbon steel, stainless steel, alloy steel, etc., the wires were passed through the refractory hearth of the heating furnace, and while a reducing atmosphere was introduced into the furnace, indirect heating such as a radiant tube burner was used. Heating was mainly done by radiant heat from the inner wall of the furnace.

However, in the conventional method, since heating is mainly performed by radiant heat, the heating time is long and rapid heating is not possible. In other words, the furnace length becomes longer, the furnace width becomes larger, equipment costs become higher, and the amount of heat radiated to the outside of the furnace increases, resulting in increased fuel consumption.

Furthermore, since a reducing atmosphere is required, running costs are increased accordingly.

By the way, the present inventor has discovered that when rapidly heating a thin wire in a short period of time, even if the atmosphere is in a weakly oxidizing region, scaleless heating (
It was discovered that non-oxidative heating) is possible. Furthermore, it has been found that when the combustion generated gas of the burner is injected along the hearth surface, the wire on the hearth is rapidly heated due to flame impingement by the burner and direct heat transfer from the hearth.

The present invention was made in consideration of the above facts, and saves energy by heating the wire in an atmosphere equivalent to a non-oxidizing atmosphere without using a reducing atmosphere in a heating furnace with a low furnace height and a short furnace length. The purpose of the present invention is to provide a method for heating wire rods that can achieve the following.

Next, the present invention will be explained according to the drawings which are one embodiment.

The heating furnace 1 includes a preheating zone 2 which is a complete combustion zone equipped with an air supply section 3 on the ceiling, a heating zone 4 in which a high speed burner 5 is installed on the ceiling and inclined toward the preheating zone 2, and a furnace side wall. and a soaking zone 6 equipped with a burner 7. At the ceiling on the side of the wire charging port 8 of the preheating zone 2, there is an exhaust gas duct 9 having an atmospheric suction means 1o and a heat exchanger 11 for controlling the exhaust gas temperature.
is the provision.

The high-speed burner 5 has an air-fuel ratio of 1.0 or less, preferably,
The combustion gas flame from the burner 5 forms a favorable atmosphere (more precisely, a weakly oxidizing atmosphere) layer S in the preheating zone 2.

That is, the furnace height is so low that the frame of the burner 5 flows along the hearth surface as described above.

Note that the exhaust gas from the heating zone 4 and the soaking zone 6 flows into the preheating zone 2, but the unburned components in the exhaust gas are completely combusted by the air supplied from the air supply section 3 and released through the exhaust gas duct 9. be done.

Next, a method of heating the wire W in the heating furnace configured as described above will be explained.

Now, each of the burners 3, 5 and 7 is operated, and the wire W
When the wire W is passed through the charging port 8, the wire W is preheated in the preheating zone 2 and then heated in the heating zone 4. In this case, the wire W passes through a non-oxidizing atmosphere layer S formed on the hearth by the high-speed burner 5, and is rapidly heated by combustion product gas flame impingement and direct heat transfer from the high-temperature hearth. In this way, since the wire W is rapidly heated, the heating time may be shorter than that of the conventional wire. However, since the wire W is rapidly heated for a short period of time in a weakly oxidizing, almost non-oxidizing atmosphere, scaleless heating is performed. Then, the wire rod heated as described above passes through a soaking zone 6 and is extracted out of the furnace. The heat curve of the heating step is shown in FIG. In addition, although the air-fuel ratio of the high-speed burner 5 was set to 0.7-0.8 in the said Example, if it is 1.0 or less, a substantially equivalent effect will be produced.

In the above embodiment, the high-speed burner 5 is fixedly arranged on the furnace ceiling, but it is made swingable, and the inclination angle can be changed depending on the material of the wire W, etc., and the thickness of the non-oxidizing atmosphere layer S or the flame impingement can be changed. may be adjusted. Furthermore, it goes without saying that the burner 7 may also be operated in the high speed bath.

As is clear from the following explanation, according to the wire heating method according to the present invention, at least the burner in the heating zone where scale is generated in the wire is a high-speed burner that burns at an air-fuel ratio of 1.0 or less; The weakly oxidizing atmosphere generated is used in place of the conventional reducing atmosphere, and the high-speed burner frame must flow along the hearth, so the high-speed burner must be installed close to the hearth. Yes, this can be solved by using a heating furnace with a low furnace height. Furthermore, since the wire is rapidly heated by flame impingement and direct heating from the hearth, the heating furnace can have a short heating zone.

As described above, the heating furnace has a low furnace height and a short furnace length, so there is little heat dissipation, and since a reducing atmosphere is not used, it is effective in saving energy.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a heating furnace in which the present invention is implemented, FIG. 2 is a sectional view taken along the line II-II in FIG. 1, and FIG. 3 is a heat curve. 1 - Heating furnace, 2 - Preheating zone, 4 - Heating zone, 5 - High speed burner, 6 - Soaking zone, S - Non-oxidizing atmosphere layer, W - Wire rod. Patent applicant Chugai Roko Kogyo Co., Ltd.

Claims (2)

[Claims] (1) A method of heating a wire by passing it over a refractory hearth of a heating furnace, in which a high-speed burner for burning at an air-fuel ratio of 1.0 or less is arranged at least in the heating zone ceiling of the heating furnace. The combustion gas from the high-speed burner is injected toward the hearth to form a non-oxidizing atmosphere layer on the hearth surface, and the wire is separated from the combustion gas flame impingement from the high-speed burner and from the hearth. Direct heat transfer 1) A heating method for a wire characterized by rapid heating. (2) A patented heating method characterized in that the air-fuel ratio is 0.7 to 0.9.