JP2000105082A - Atmosphere continuous heating furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To raise the temperature of an article to be heat treated gently and quickly up to a highest target temperature by providing a preheating chamber at the predriving part of a heating chamber, heating the low temperature atmosphere in the preheating chamber by feeding it into the high temperature heating chamber by means of a fan and then circulating the heated atmosphere back to the preheating chamber. SOLUTION: Combustion radiation pipes 2 are fixed to the ceiling part and the bottom part of a heating chamber 1, a preheating chamber 3 is disposed at the predriving section of the heating chamber 1 and a fan 5 is secured above the inlet 4 of the preheating chamber 3. Atmosphere is sucked from the preheating chamber 3 by operating the fan 5 and fed through an atmosphere moving passage 6 into a part of the heating chamber 1 before being returned back to the preheating chamber 3. A conveyor belt 8 is disposed in the furnace and a thermocouple 10 disposed closely to the conveyor belt 8 substantially in the center of the heating chamber 1 is connected to a combustion control circuit for the combustion radiation pipes 2 in order to keep the temperature of the heating chamber 1 at a desired level. Further, a thermocouple 11 is provided above the central part of the preheating chamber 3 and connected with a rotation control circuit for the fan 5 in order to keep the temperature of the preheating chamber 3 at a desired level.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION In a continuous furnace, it is often necessary to raise the temperature of an object to be heated while slowly controlling the heating rate up to a target maximum heating temperature. The present invention
An atmosphere continuous heating furnace that moves a part of the heat of the heating chamber to the preheating chamber in the pre-heating zone of the heating chamber so that the medium-temperature heating of the object to be heated and the subsequent high-temperature heating can proceed slowly and quickly. To provide.

[0002]

2. Description of the Related Art In an atmosphere continuous heating furnace provided with a long combustion radiation tube along the longitudinal direction of a tunnel-shaped heating chamber, the object to be heated carried therein is rapidly heated to a target maximum temperature. You. Such rapid heating results in non-uniform heating of the object to be heated, resulting in distortion of the object to be heated due to heat. It also leads to poor hot reaction of the processed material.

[0003]

Therefore, there is a need for an economical atmosphere continuous heating furnace which can slowly and quickly raise the temperature of the object to be heated to the desired maximum heating temperature, and which has a simple structure and is economical.

[0004]

According to the present invention, a preheating chamber having no heating means such as combustion or electric heating is provided in a precursor portion of a heating chamber, and a low-temperature atmosphere in the preheating chamber is blown by a blower to a high-temperature heating chamber. The heated atmosphere is returned to the preheating chamber, where the heat is transferred to the object to be heated, and the cooled atmosphere is again sent to the heating chamber by the blower to heat the preheating chamber. Is performed.

That is, most of the heat generated by the combustion radiant tube provided in the heating chamber is consumed for maintaining the temperature of the heating chamber itself, but part of the generated heat is part of the preheating chamber and a part of the heating chamber. Heats a part of the atmosphere gas circulating between the preheating chamber and the heating chamber to compensate for the temperature of the preheating chamber. In the heating chamber, a temperature detector is placed at a position representative of the heating function to control the combustion of the combustion radiation tube in the heating chamber, while the temperature detector provided in the preheating chamber controls the amount of transfer of the atmosphere by the blower. By controlling, the temperature of the preheating chamber is adjusted to a desired value. In this case, the control of the temperature of the preheating chamber is possible only in a range lower than the temperature of the heating chamber, and it is needless to say that the temperature is controlled within this range.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a suitable continuous atmosphere heating furnace according to the present invention will be described with reference to the accompanying drawings.

[0007] Two 140 mm diameter combustion radiation tubes each having a diameter of 140 mm were attached to the ceiling and bottom of the heating chamber 1 having a width of 500 mm, a length of 4500 mm and an effective height of 200 mm so as to extend in the longitudinal direction of the heating chamber 1.

Reference numeral 3 denotes a preheating chamber having a width of 500 mm, a length of 1800 mm, and an effective height of 200 mm, which is provided in a precursor portion of the heating chamber 1 so as to communicate with the heating chamber 1.
A multi-blade blower 5 was fixed above the inlet 4 of the preheating chamber 3. The blower 5 sucks the atmosphere from the preheating chamber 3, sends the atmosphere into a part of the heating chamber 1 through an atmosphere moving passage 6 provided above the preheating chamber 3, and returns the atmosphere to the preheating chamber 3. . A cooling chamber 7 having a water-cooled structure is attached to a subsequent portion of the heating chamber 1.

Reference numeral 8 is a conveyor belt circulating in the furnace, and reference numeral 9 is a tube for sending atmospheric gas into the furnace. Reference numeral 10 denotes a thermocouple provided substantially in the center of the heating chamber 1 and close to the conveyor belt 8.
Is connected to a combustion control circuit of the combustion radiant tube 2 in order to keep the temperature at a desired value. Reference numeral 11 denotes another thermocouple attached to the upper center of the preheating chamber 3, which rotates the blower 5 in order to keep the preheating chamber 3 at a desired temperature, that is, moves the atmosphere circulated by the blower 5. Leads to a circuit that controls the quantity.

When the temperature near the thermocouple 10 in the heating chamber 1 is 60
The combustion of the combustion radiation tube 2 was controlled so as to maintain 0 ° C., and the rotation of the blower 5 was controlled such that the temperature near the thermocouple 11 in the preheating chamber 3 was maintained at 350 ° C. At this time, the distribution of the in-furnace temperature of the entire furnace became like a curve shown in the lower part of FIG.

Using a continuous furnace in which the temperature inside the furnace was maintained and nitrogen gas at a rate of 40 cubic meters per hour was sent from the atmosphere gas insertion pipe 9, parts machined from an aluminum plate were supported by assembling supports. Heat exchanger assembly (width 8.5
cm, height 22.5cm, length 23.0cm, weight 44
6g).

When this assembly was put on the belt 8 and passed through the entire furnace in 40 minutes, the assembly was gradually heated in the preheating chamber 3 at 350 ° C. and then heated to 600 ° C. Te brazing was performed. As a result, normal brazing could be performed without causing distortion or the like due to rapid heating.

In addition, as a trial, the control temperature of the heating chamber 1 of this furnace was set to 1100 ° C., the control temperature of the preheating chamber 3 was set to 600 ° C., and 40 cubic meters of the exothermic type modified gas having a dew point of 18 ° C. were sent into the furnace as a protective atmosphere. As a result of automatic control, the temperature of the heating chamber 1 was maintained at 1100 ° C. ± 4 ° C., and the temperature of the preheating chamber 3 was maintained at 600 ° C. ± 3 ° C.

[0014]

The atmosphere continuous heating furnace according to the present invention can gradually raise the temperature of the object to be heated to a target temperature.
Moreover, since a complicated heating means or the like is not used in the preheating chamber, the economical effect is great.

[Brief description of the drawings]

FIG. 1 is an explanatory side sectional view of a continuous furnace according to the present invention and a curve showing the distribution of the temperature in the furnace.

[Explanation of Signs] 1-heating chamber 2-gas heating radiation tube 3-preheating chamber 4-inlet of preheating chamber 5-air blower for atmosphere transfer 6-atmosphere transfer passage 7-cooling room 8-conveyor belt 9-atmosphere gas Inlet pipe 10-Thermocouple in heating chamber 11-Thermocouple in preheating chamber

Claims (1)

[Claims] 1. A heating chamber provided with a heating means, and a preheating chamber which communicates with the heating chamber in advance of the heating chamber, wherein an atmosphere in the preheating chamber is sent to the heating chamber and returned to the preheating chamber. An atmosphere continuous heating furnace in which a blower is provided in a preheating chamber, and the temperature of the preheating chamber is maintained at a predetermined temperature lower than the temperature of the heating chamber by selecting an amount of air blown by the blower.