JPS637323A - Heating furnace - Google Patents

Abstract

PURPOSE:To decrease the generation of skid marks and to improve productivity by changing the disposition of stationary skid pipes to the middle or moving skid pipes on both sides of the extension lines of the stationary skid pipes from a charging port side of a heating furnace. CONSTITUTION:The moving skid pipes 2 are provided on the same straight line from the charging port 9 to an ejection port 10 of the heating furnace 3. The stationary skid pipes 1 are provided to the middle of the adjacent moving skid pipes 2 from the port 9 up to the end of a heating zone 5. The stationary skid pipes 1-l are provided to the intermediate positions of the stationary skid pipes 1 and the moving skid pipes 2 up to the heating zone 5 and are provided to a forked shape on both sides of the extension lines of the stationary skid pipes 2 up to the heating zone 5 in a holding zone 6. The quantity of heat input from the bottom surfaces increases when the materials W to be heated enter the holding zone 6. The temp. distribution at the time of ejection is thereby uniformized.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a heating furnace that heats a cold steel billet or a hot steel billet to a temperature necessary for subsequent rolling operations and retains the heat by LAD.

(Prior art) As is well known, in a walking beam type heating furnace, there is a moving beam and a fixed beam, and the moving beam moves back and forth up and down to transport all the steel pieces inside the furnace while being alternately placed on the moving beam and the fixed beam. The feature is that the steel billet is heated to the specified temperature.

By the way, these conventional techniques include a fixed skid pipe 1 as shown in FIG. The arrangement of the moving skid knobs 2 in the furnace length direction is linear and colinear from the charging side to the extraction side of the heating furnace 3. This means that the same part of the steel billet always comes into contact with these skid pipes 1 and 2 that support and convey the steel billet W in the furnace. The inner surface of the skid pipe is cooled by low-temperature fluid, so if the contact area between the skid pipe and the steel billet is on the same line from the charging side to the extraction side of the furnace, the temperature of the contact area will be lower than that of the non-contact area. Become.

Further, the lower surface of the steel billet between the fixed skid pipe 1 and the movable skid pipe 2 has a large shadow coefficient as shown in FIG. 8, so the temperature of the steel billet becomes high.

In other words, the shadow coefficient is the total of 8 degrees of positive and negative heat blocked by the fixed and moving skid pipes, assuming that radiant heat is emitted uniformly from the hearth on the bottom. The larger the value, the more easily the radiant heat from the lower surface enters the heated material W. In other words, this indicates that the temperature of the heated material W increases.

As described above, the temperature of the material to be heated on the skid, especially the fixed skid, is low, but the temperature of the material to be heated between the fixed skid knob 1 and the moving skid knob 2 is higher than this. This temperature difference between the heated material in the low-temperature area and the high-temperature area is generally referred to as a skid mark.

These skid marks lead to an increase in the thickness deviation of the finished product when the heated material is a plate-like material, and an increase in the deviation of the finished product thickness when the heated material is a shaped steel material or a pipe material.

Conventional countermeasures against skid marks during operation have been to raise the temperature of the atmosphere inside the furnace in order to raise the temperature of the heated material in the low-temperature part that comes into contact with the skid. The amount generated was also increasing, and the unit heat consumption was worsening.

Similarly, as an operational countermeasure, there is a method of increasing the heating time t to reduce skid marks, but this reduces production capacity and also worsens the fuel consumption rate.

In addition, as an example of equipment countermeasures for existing skid marks, for example, Japanese Patent Laid-Open No. 56-16620, Utility Model Application No. 57-18
As described in Japanese Patent No. 5749 and as shown in FIG. 9, the fixed skid pipe 1 is partially shifted to one side in the furnace width direction at a certain position in the furnace length direction, and the skid pipe comes into contact with the material to be heated. Measures have been taken to reduce the skid ratio by changing the position of heating and at the same time changing the shadow coefficient on the lower surface of the heated material. However, in this case, when the fixed skid pipe 1 is shifted to one side, the shadow coefficient becomes as shown in 111 in FIG. 10).While the heat input amount on one side of the lower surface becomes smaller, the heat input amount on the other side is not improved. In this case, it is estimated that skid marks will be small in part of the temperature distribution of the heated material extracted from the furnace as shown in Figure 11, but this heated material will have temperature deviations at unequal intervals in the longitudinal direction. Hold rolling is also not preferred.

(Problems to be Solved by the Invention) The present invention solves these drawbacks and aims to () fix the skid! In order to prevent the generation of low-temperature areas in the material to be heated on the eaves, by shifting the fixed skid nob to both sides, the temperature of the lowest-temperature areas increases rapidly and accelerates heating by the time of extraction. .

(b) By shifting the fixed skid blades to both sides to the position where the material to be heated reaches the highest temperature between the skid blades in the oven width direction, or in the vicinity thereof. , the subsequent temperature rise at the position where the temperature of the material to be heated was at its highest before shifting is slowed down, the temperature at the highest part of the material to be heated during extraction is suppressed, and the temperature is made uniform.

The skid mark, which is the temperature difference between the heated material, is reduced by (CHa) and (b).

(Means for Solving the Problems) The gist of the present invention is to provide a heating furnace equipped with a fixed skid, four pipes, and a movable skid pipe. The heating furnace is characterized in that fixed skid pipes are provided on both sides of an extension line of the skid pipe, and fixed skid pipes are arranged between the extension line and the movable skid pipe adjacent to the extension line.

(Example and operation) Hereinafter, the present invention will be described in detail based on an example with reference to the drawings.

Trickle burners 7 are installed in the preheating zone 4 of the heating furnace 3, the upper and lower parts of the heating zone 5, and the lower part of the soaking zone 6, and a ceiling burner 8 is installed in the upper part of the soaking zone 6. The material to be heated W enters through the charging port 9, and is connected to the fixed skid knob 1 and the movable skid pipe 2.
It is conveyed through the furnace while being alternately placed and heated to the target extraction temperature for extraction.

As shown in the plan view of the heating furnace 3 of the present invention in the embodiment shown in FIG. 1, the movable skid pipe 2 is provided substantially on the same straight line from the charging port 9 to the extraction port 10.

The fixed skid pipe 1 is provided between the movable skid pipe 2 and other movable skid pipes and eaves 2 in a positional relationship in the furnace width direction from the charging port 9 to the end of the heating zone 5.

In the soaking zone 6, the fixed skid pipe 4 f1-1 is located at the intermediate position (or close to it) between the fixed skid pipe 1 and the movable skid pipe 2 up to the heating zone 5, and is an extension of the fixed skid pipe 2 up to the heating zone 5. It is provided in a bifurcated shape on both sides.

FIG. 3 shows a cross section of the soaking zone 6 in which the fixed skid knob 1 is shifted to both sides.

In this way, the lowest temperature area occurs in the heated material W on the fixed skid pipe 1 up to the heating zone 5, and the highest temperature area occurs between the fixed skid pie f1 and the moving skid 4ide 2. However, when the heated material W enters the soaking zone 6 where the fixed skid pipe 1 has been shifted to both sides, the shadow coefficient from the bottom where the fixed skid pipe 1 was conventionally This has been greatly improved, and the amount of heat input from the bottom surface is large, and the temperature of the lowest temperature area increases rapidly. Note that the broken line in the figure indicates the shadow coefficient up to the heating zone 5.

Furthermore, up to the heating zone 5, there is a fixed skid pipe 1-1 that is located between the fixed skid pipe 1 and the movable skid pipe 2, and has been shifted to the position of the heated material W, which is the hottest part.)
, as can be seen from Fig. 4, the shadow coefficient of the lower surface at that position is small, and the amount of heat input from the lower surface is reduced.
The temperature rise will be slow.

Therefore, the temperature of the heated material W to be extracted is as shown in FIG. 5, and as shown in FIG. 6, which shows the temperature distribution of the heated material W during conventional extraction.

The optimum position for shifting the fixed skid pipe 1 to both sides is determined by the throughput, the furnace atmosphere temperature, etc.

In this embodiment, the fixed skid pipe 1 is shifted to both sides in the soaking zone 6, but the shift is not limited thereto and may be shifted from the rear half or the middle of the heating zone 5.

According to the present invention, the method of shifting the fixed skid knob 1 includes (,) shifting the fixed skid from the charging side from a certain position to one side, and shifting the other side by slightly changing the shift start position. .

(b) After the fixed skid is shifted, the shift amount may of course be corrected again on the extraction side depending on the constraints of the extraction machine on the extraction side, but this is also included.

(c) This fixed skid shift can be applied to Zosher type heating furnaces as well as walking beam type heating furnaces.

(Effects of the Invention) The effects of the invention are as follows: By greatly reducing skid marks, the productivity of heated materials can be improved.

(b) Due to the skid mark reduction effect, the extraction temperature of the heated material is lowered and the unit heat consumption is reduced.

(c) Furthermore, by reducing the size of skid marks, quality improvements such as a reduction in product thickness deviation and a reduction in product wall thickness deviation can be achieved during rolling.

(d) Since the extraction temperature deviation is small, the quality of the conventionally low-temperature part is improved, and the difference in quality with other parts is also reduced, resulting in improved quality such as uniformity of quality.

[Brief explanation of drawings]

FIG. 1 is a plan view of a heating furnace according to an embodiment of the present invention. Figure 2 is a side view of the same, and Figure 3 is a sectional view of the soaking zone of the heating furnace. Fig. 4 is a diagram for explaining the action of an embodiment of the present invention, Fig. 5 is a diagram for explaining the action of uniform heating in an embodiment of the invention, and Fig. 6 is a conventional case. 7 is a diagram showing an example of a conventional heating furnace. FIG. 8 is a diagram for explaining the effect of a conventional heating furnace. Figures 10 and 1 showing other examples of heating furnaces.
FIG. 1 is a diagram for explaining the operation in a conventional other-side heating furnace. 1: Fixed skid pipe 2: Movable skid pipe 3:
Heating furnace 4: Pre-heating zone 5: Heating zone 6: Soaking zone 7: Axial flow/9-seat 8: Ceiling burner 9: Charging port
10: Extraction port Figure 4 Figure 5 Figure 8

Claims (1)

[Claims] In a heating furnace equipped with a fixed skid pipe and a movable skid pipe, from a predetermined position in the soaking zone or heating zone of the heating furnace, the fixed skid pipe is installed on both sides of the extension line of the fixed skid pipe from the charging port side, and the extension line is connected to the extension line. A heating furnace characterized by being installed in the middle of adjacent moving skid pipes.