JP2000105081A - Gas heating atmosphere continuous furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To raise the temperature of a product to be heated gently from the cold part toward the hot part by fixing a radiation pipe along the longitudinal direction of the furnace chamber of a continuous furnace, extending one end thereof from the cold part to the outside of the furnace as an exhaust opening and coupling the other end extending through the hot part with the combustion chamber as a hot gas suction/ introduction opening. SOLUTION: A gas combustion chamber 2 is disposed at the upper part of the heating chamber 1 of a continuous furnace and snaking heat radiation pipes 3 are arranged on the ceiling and the bottom part of a lower heating chamber 1 such that the heat radiation pipes 3 extend in the longitudinal direction of the heating chamber 1 as a whole. The upper and lower heat radiation pipes 3 are coupled, at the end part close to the inlet 4 of the heating chamber 1, with an exhaust pipe 6 where a negative pressure actions and coupled, at the other end part close to the outlet 5 of the heating chamber 1, with the gas combustion chamber 2. A conveyor belt 8 is disposed in the heating chamber 1 in order to braze a semi-complete product of heat exchanger fixed with a copper phosphorous brazing metal while carrying. Temperature of the semi-complete product is increased gently in order to eliminate the problem that strain is increased by the difference in the coefficient of thermal expansion to cause dimensional fluctuation or incomplete brazing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a continuous furnace in a gas heating atmosphere used for heat-treating a product to be heated such as a metal or a metal compound.

[0002]

2. Description of the Related Art In a continuous furnace of this kind, in many cases, the relationship between the temperature and the time during which the temperature reaches the final heating target temperature is set and adjusted in accordance with the processing purpose of the object to be heated. Is required.

For this purpose, the heating chamber is divided into several sections in the longitudinal direction, and the temperature of each section is set and controlled. Therefore, the radiant tube burner is installed in a direction transverse to the longitudinal direction of the furnace, and one or several burners guarantee the temperature of each section.

[0004]

However, with such a heating method, it is difficult to reduce the impact of the rapid heating or the reaction caused by the rapid heating.

[0005] Therefore, there is a demand for a continuous furnace in a gas-heated atmosphere in which the temperature of a product to be heated can be increased gradually and without interruption from a low-temperature portion to a high-temperature portion without impairing the heating effect.

[0006]

According to the present invention, a radiant tube for heating the furnace chamber is installed along the longitudinal direction of the furnace chamber of the continuous furnace, and one end of the radiant tube is connected to a low temperature part of the furnace. It is taken out of the furnace and used as an exhaust port, and the other end extending through the high-temperature section is connected to a combustion chamber provided separately from the heating furnace chamber both thermally and atmospherically, and is used as a hot gas intake / inlet port. Is what you do.

[0007] The hot gas entering the radiation radiating tube from the suction port is
The heating chamber moves at a high speed from the high temperature section to the low temperature section, and gradually dissipates heat with the movement to keep the entire heating chamber under a desired temperature gradient. In other words, the product to be heated is gradually heated as it progresses from the low-temperature portion to the high-temperature portion.However, the flow of the hot gas in the radiation radiating pipe is reversed in such a way that the progress of the product to be heated is reversed. Make it. In this way, the product to be heated is slowly heated, while the temperature of the hot gas is gradually lowered, so that the heating efficiency can be maximized.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a continuous furnace in a gas heating atmosphere according to the present invention will be described below with reference to the drawings.

In FIG. 1 which is a plan view of a continuous furnace of the present invention in which a part is sectioned, and FIG. 2 which is a side sectional view, a gas combustion chamber 2 is provided above a heating chamber 1 of the continuous furnace. And a meandering radiation radiating tube 3 is provided on the ceiling and bottom of the heating chamber 1 so as to extend in the longitudinal direction of the heating chamber 1 as a whole. Reference numeral 4 denotes an inlet of the heating chamber 1, and reference numeral 5 denotes an outlet.

Each heating chamber 1 of the upper and lower radiation radiating tubes 3
The end near the inlet is connected to the exhaust pipe 6 where negative pressure works.
The other ends of the heating chamber 1 near the outlet 5 are connected to the gas combustion chamber 2 respectively.

Reference numeral 7 denotes a burner. In this embodiment, methane gas is burned to generate hot gas. Set the width of the gas combustion chamber 2 to 7
The heating chamber 1 was 50 mm, the height was 200 mm, the length was 2000 mm, the width of the heating chamber 1 was 750 mm, the height was 400 mm, and the length was 4230 mm.

A heat-resistant steel conveyor belt 8 having a width of 600 mm was attached to the heating chamber 1. The operation of the belt 8 was controlled so as to pass through the heating chamber 1 having a length of 4230 mm in 22 minutes.

[0013] The brazing of a semi-finished product of a heat exchanger comprising 12 copper parts supported by a stainless steel support and fitted with a phosphorous copper brazing material was performed in this continuous furnace. Was done.

The maximum temperature in the heating chamber 1 is maintained at 865 ° C. At this time, the temperature of the atmosphere gas (nitrogen 40%, hydrogen 40%, carbon monoxide 20%) near the inlet 4 of the heating chamber is 23.
The temperature of the exhaust gas from the discharge pipe 6 was 348 ° C.

In the heating chamber 1 under such a temperature distribution, the above-mentioned semi-finished product gradually rises in temperature, and stays in the heating chamber for 22 minutes to reach a target temperature of about 865 ° C. for 4 minutes and 20 seconds. It was confirmed that it was kept and technically satisfactory.

It is to be noted that this kind of the object to be heated is rapidly reduced to 86.
When placed in a furnace near 5 ° C., a large strain occurs due to the difference in thermal conductivity and coefficient of thermal expansion between the steel part and the stainless steel support, causing dimensional change and poor soldering. In the example, such a situation did not occur at all.

In the above embodiment, the gas combustion chamber 2 is provided independently of the heating chamber 1 and is a part of the furnace. However, the gas combustion chamber may be provided separately from the continuous furnace. That is. Instead of providing the gas combustion chamber separately, a part on the high-temperature side of the radiation radiator tube 3 may be used as the combustion chamber, and the hot gas may be generated here.

Further, the fuel ratio of the combustion gas introduced into the radiant heating tube maintained at a negative pressure is supplied in a state of excess fuel, that is, in a state of insufficient oxygen, and oxygen or air is sucked into the tube in the middle of the radiant heating tube. Then, the heat of the secondary combustion may be promoted downstream of the intermediate portion to raise the temperature of the downstream portion.

[0019]

As described above in detail, according to the continuous furnace of the gas heating atmosphere according to the present invention, the temperature of the object to be heated can be moderately increased, and the thermal efficiency of the hot gas used for the temperature increase can be improved. There is a great excellent effect.

[Brief description of the drawings]

FIG. 1 is a plan view showing a cross section of a part of a continuous furnace in a gas heating atmosphere according to the present invention.

FIG. 2 is a side sectional view of the continuous furnace.

[Explanation of symbols]

 1-heating chamber 2-gas combustion chamber 3-radiation radiator pipe 4-heating chamber inlet 5-heating chamber outlet 6-discharge pipe 7-burner 8-conveyor belt

Claims (4)

[Claims] 1. A long tunnel-shaped heating chamber for continuously heating a product to be heated under a desired atmosphere,
The heating chamber has a belt for transporting the product to be heated from the inlet to the outlet, and a radiation radiating tube which is outside the transport path of the belt and extends in the longitudinal direction of the heating chamber to heat the heating chamber. A gas heating atmosphere continuous furnace in which one end of the radiation radiating tube near the outlet of the heating chamber is used as a hot gas introduction side, and the other end near the entrance of the heating chamber is used as a hot gas discharge side. 2. The gas heating atmosphere continuous furnace according to claim 1, wherein a combustion chamber for producing the hot gas sent to the radiation radiator tube is provided independently of the heating chamber. 3. The continuous gas heating atmosphere furnace according to claim 1, wherein a combustion chamber for producing a hot gas sent to the radiation radiating pipe is provided in the radiation radiating pipe. 4. The continuous gas heating atmosphere furnace according to claim 1, wherein a pipe for supplying air or oxygen is connected in the middle of the radiation radiating pipe for sending the hot gas.