JPS5939482B2 - Heating method in flame shock type heating furnace - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heating method in a carburizing impact heating furnace in which the flame of a burner is directly blown onto an object to be heated.

Induction heating, radiation heating, flame impact heating, and the like are well known methods for heating billets and the like.

First, the induction heating method takes a short time to heat the object to be heated, such as a billet, and heats up quickly. However, in the case of objects with a large diameter, the temperature distribution tends to be uneven, and the running cost is high due to high power consumption. It has the disadvantage of being expensive.

In addition, in the radiation heating method, since the amount of heat transferred by convection is small, heating takes time as shown in FIG. 1, and therefore a long furnace length is required, which inevitably increases equipment costs.

On the other hand, with the flame shock heating method, although the heating time is significantly shortened, the temperature distribution tends to be extremely uneven as shown in Figures 2 and 3, and requires precision similar to precision parts. There was a drawback that made it unsuitable for those who were exposed to it.

Therefore, as demand has increased in recent years, the shape of objects to be heated has become larger, and uniform temperature distribution has become required, conventional heating methods have become inconvenient.

The present invention has discovered a new heating method in a flame shock type heating furnace in order to eliminate the numerous deficiencies associated with the prior art as described above.

Therefore, the present invention will be explained below with reference to the embodiment diagrams shown in FIGS. 4 to 6.

In the heating zone A, a large number of flame shock type burners 1 are arranged in parallel on both sides of the furnace walls so as to face the object to be heated C passing through the center, and 2 indicates an exhaust port and 3 indicates an inlet door.

The object to be heated C is moved in the heating zone A in the direction of the arrow in the figure by a so-called walking beam type conveyor, 4 is a movable beam, and 5 is a large number of horizontally supporting movable beams 4 that can move forward and backward. The arm 6 is a cylinder that rotates the arm 5 about a fulcrum 7 and moves the movable beam 4 up and down, and 8 is a cylinder that moves the movable beam 4 forward and backward. The object to be heated C passes through the heating zone A and is transported to the soaking zone B provided subsequently.

Reference numeral 9 indicates support metal fittings provided on both sides of the hearth to support the object to be heated C when the movable beam 4 descends, and reference numeral 10 indicates water provided to prevent the gas in the furnace from leaking from the hearth to the outside. It is a sealing mechanism.

Therefore, the soaking zone B is provided with a blower 14 driven by an electric motor 13 to forcibly circulate the gas in the furnace and blow out hot air from multiple nozzles 12 of a pair of plenum chambers 11 provided on both sides of the heated object passage. is provided in the duct 15.

Note that 16 indicates a burner that heats the furnace gas in the soaking zone B to a predetermined temperature.

Next, the heating method of this flame shock type heating furnace will be explained with reference to FIG. The surface temperature of the object to be heated is rapidly heated to 702°C.

At that time, the center temperature of the heated object C is 668° C., and the heated object C is transferred to the subsequent soaking zone B with a large temperature difference.

In the soaking zone B, the nozzle 12 of the plenum chamber 11
The temperature of the hot air blown out from the heating zone A to the soaking zone B
It is assumed that the surface temperature of the object C to be heated is set at about 680°C, which is lower than the surface temperature of 702°C and higher than the center temperature of 668°C.

That is, in the soaking zone B, by forcibly blowing low-temperature hot air to the heated object C, the surface temperature of the heated object C is lowered to 68%.
The central temperature is lowered to 8°C and raised to 670°C, thereby making the temperature distribution uniform in a short time.

FIG. 8 shows an embodiment of the heating furnace of the present invention, in which the same components as in FIG. 4 are designated by the same reference numerals.
By introducing the high-temperature waste gas generated by the combustion of the burner 1 into the soaking zone B through the introduction path 17, the heat source in the soaking zone B is made unnecessary. The opening amount is adjusted according to the required temperature of the soaking zone B to save energy.

As explained above, in the heating zone, a high-temperature flame is directly blown onto the object to raise the temperature in a short time, and in the soaking zone, hot air at a set temperature as described above is applied from the nozzle of the plenum chamber. By blowing directly onto the hot material, uniform heating can be achieved in a short time, making the furnace length much shorter than before, resulting in lower equipment costs.Also, the overall furnace is more compact, making it easier to raise the temperature of the furnace. It is advantageous in that it is quick, suitable for intermittent operations such as daytime operations only, and can be operated at low running costs.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the temperature rise of a heated object by the conventional radiation heating method, Figure 2 is a diagram showing the temperature rise of a heated object by the conventional flame shock heating method, and Figure 3 is a diagram showing the temperature rise of the heated object by the conventional flame shock heating method. Fig. 2 is a diagram showing the temperature distribution of the heated object heated by the method, Fig. 4 is a longitudinal cross-sectional view of the flame shock type heating furnace according to the present invention, and Fig. 5 is a diagram showing the X-X line of Fig. 4. 6 is a sectional view taken along the Y-Y line in FIG. 4, FIG. 7 is a diagram showing the temperature increase of the object to be heated by the heating method according to the present invention, and FIG. 8 is a diagram showing the flame according to the present invention. It is a longitudinal cross-sectional view showing another embodiment of the impact type heating furnace. A... Heating zone, B... Soaking zone, C...
... Heated object, 1 ... Burner, 11 ...
...to plenum channel 12...nozzle, 17.
...Introduction route.

Claims (1)

[Claims] 1. A heating zone in which objects to be heated are continuously conveyed is provided with a burner that sprays flame directly onto the objects to be heated, and a soaking zone provided subsequent to the heating zone is provided with a burner that sprays flame directly onto the objects to be heated. A plenum chamber is provided in which hot air is blown directly from a nozzle to the heated object, and the temperature of the hot air is lower than the surface temperature of the heated object when it is transferred from the heating zone to the soaking zone. A heating method in a flame shock type heating furnace characterized by setting the temperature higher than the center temperature of the furnace. 2. A heating method in a flame shock type heating furnace according to claim 1, characterized in that waste gas in a heating zone generated by burner combustion is introduced into a soaking zone.