JPS61199012A - Heating furnace for cast iron or steel billets - Google Patents

Abstract

PURPOSE:To provide the titled heating furnace which decreases always effectively skid marks without being affected by various conditions in the operation of the furnace and has excellent durability by providing a roller hearth furnace which intersects orthogonally with the continuous heating furnace and can reheat cast iron and steel billets on the outlet side of the heating surface in contact therewith. CONSTITUTION:The cast iron or steel billets 3 which are loaded from the inlet side 1' of the continuous heating furnace 1 onto stationary skids 4b are intermittently moved toward the outlet side 1'' of the furnace 1 as shown by an arrow (a) by the rectangular cycle motion of the moving skids 4a. The billets 3 charged into the roller hearth furnace 9 from the tail ends 4b' of the skids 4b are received by a roll array 10 arranged in the direction intersecting orthogonally with the arrow (a) direction and are conveyed toward an ejection port 9b. The ingots 3 on the array 10 are heated, soaked or held to and at the necessary temp. by burners 8a, 8b provided respectively to the upper part and lower part sandwiching the array 10. As a result, the skid marks of the billets 3 are always effectively reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a heating furnace for cast iron or steel pieces that does not cause uneven heating such as skid marks.

(Prior art) A large number of cast iron pieces or steel pieces (hereinafter referred to as cast iron/steel pieces)
Continuous heating furnaces, which sequentially and continuously heat materials to a predetermined rolling temperature while conveying them through the furnace, have traditionally been equipped with a pusher set as shown in Figure 3, a walking beam type as shown in Figure 4, or a walking beam type as shown in Figure 5. There is a walking method shown in the figure below.

In the pusher-set heating furnace (LA), cast iron/steel pieces (3) are placed on skid rails (2) laid on the hearth, and the cast iron/steel pieces (3) are pushed forward by the following cast iron/steel pieces to the exit side of the furnace. Transport method. Walking beam heating furnace (l
b) is a conveyance system in which the cast iron/steel piece (3) placed on the fixed skid (4b) is moved to the outlet side of the furnace by the rectangular cyclic movement of the moving skid (4a).

Similarly to the above-mentioned walking beam type heating furnace, the walking hearth type heating furnace uses the rectangular cyclic movement of the movable hearth (5a) to heat the cast iron/steel pieces (3) placed on the fixed hearth (5b). This is a transport type that moves it to the exit side of the furnace.

However, the cast iron/steel pieces heated in such conventional continuous heating furnaces are heated by the skid rail (2), the movable/fixed skids (4a) (4b), or the movable/fixed hearth (5a) (5b). ), etc., where the temperature is low and dark brown so-called skid marks are produced. This is because the in-furnace conveyance equipment such as the skin trail (2) is cooled to prevent thermal damage.
Cast iron and steel pieces with such skit marks have a significant negative impact on product quality, such as deteriorating the dimensional accuracy of the product during rolling, so various measures have been taken to prevent skit marks. I've been exposed to it.

For example, ■ Walking beams that reduce skid marks by shifting part of the array of fixed skids to the left and right in the direction of travel, and shifting the contact areas of cast iron and steel pieces with the fixed skids (unexamined patent application). Showa 58-1172
(No. 5), ■ In-furnace steel reversing device that aims to reduce skid marks by reversing cast iron/steel pieces in the furnace and changing the contact area with the fixed skid (Japanese Patent Laid-Open No. 57-114)
No. 608). ■The skid button attached to the skid pipe is made of high-temperature, high-strength ceramics, eliminating the need for water cooling to the skid pipe, thereby reducing skid marks.
No. 16) etc.

(Problems to be Solved by the Invention) However, in the case of the above-mentioned countermeasure example (2), no effect can be obtained unless the number of shifts is appropriately changed depending on the time in the furnace of the cast iron/steel pieces. Therefore, in actual operations, if the time in the furnace of cast iron or steel pieces deviates from the schedule, no effect can be expected from the shift. In case of the above countermeasure example (■), it is effective in special cases such as when cast iron or steel pieces are lightweight, but it lacks practicality when dealing with general heavy slabs. Further, in the case of the above countermeasure example (2), although it is effective during the initial setting, there is a problem in durability, and the effect of reducing skid marks decreases over time, resulting in a lack of permanence.

The present invention was made in view of these circumstances, and was developed to
Skit marks that inevitably occur in continuous heating furnaces for steel pieces are affected by various furnace operating conditions, such as differences in the time in the furnace between cast iron and steel pieces and differences in weight between cast iron and steel pieces. The purpose of the present invention is to provide a continuous heating furnace for cast iron and steel pieces that can effectively reduce skid marks at all times and has excellent durability.

Hereinafter, the present invention will be described in detail based on the accompanying drawings.

(Means for solving the problem) Fig. 1 is a diagram illustrating an example of a cast iron/steel piece preheating furnace according to the present invention, in which (a) is a longitudinal sectional side view, and (b) is a side view of the preheating furnace for cast iron and steel pieces according to the present invention. 1
FIG. 2 is a plan view within the broken line circle in Figure (A).

As shown in FIGS. 1(a) and 1(b), the cast iron/steel piece preheating furnace of the present invention is provided at the outlet side of a continuous heating furnace (1) having a conveying facility for cast iron/steel pieces (3) in the furnace. The above heating furnace (1) is in contact with
A row of rolls (6) for transporting the cast iron/steel piece (3) is provided in a direction perpendicular to the direction of transport of the cast iron/steel piece (3) so as to be rotatable in forward and reverse directions, and the upper and lower sides of the furnace sandwiching the roll row are provided. Roller hearth furnace (9) equipped with heating burners (8a) and (8b)
It is characterized by having the following.

In the present invention, the continuous heating furnace (1) having a conveyance facility in the furnace may be a continuous heating furnace of any known conveyance type, such as a pusher set, a walking hearth type, or a walking hearth type. The continuous heating furnace (1) in the illustrated example is equipped with a walking beam type conveyance facility, and the cast iron is charged onto the fixed skid (4b) from the entrance side (B) of the continuous heating furnace (1). - The steel piece (3) is moved to the outlet side (1'') of the furnace (1'') as shown by arrow a by the rectangular cyclic movement of the moving skid (4a), that is, repeating the upward-advancing-downward-backward movement. ) is advanced intermittently, during which the cast iron/steel piece (3) is heated to a predetermined rolling temperature by several rows of burners (7) installed on the ceiling of the furnace (1).Continuous heating furnace (1) The combustion method is not limited to the roof combustion method shown in the illustrated example, but may be a side combustion method, an axial flow combustion method, or a combination of these methods.

The tail end (4b') of the fixed skid (4b) is inserted from the outlet side (1'') of the continuous heating furnace (1) into a roller hearth furnace (9) connected to the outer wall of the outlet side. The medical chamber is supported by a beam (4) that stands on the hearth of a roller hearth furnace (9).

The roller hearth furnace (9) receives cast iron/steel pieces (3) that are introduced into the hearth furnace (9) from the tail end (4b') of the fixed skid (4b), as shown in FIG. 1 (b). The roll row (10) that is stopped and transported to the extraction port (9b) is in a direction (arrow b) perpendicular to the transport direction (arrow a) of the cast iron/steel pieces (3) in the continuous heating furnace (1). are arranged in In other words, the conveying direction (arrow b) of cast iron/steel pieces (3) in the roller hearth furnace (9) is transferred to the continuous heating furnace (1).
If it is the same as the conveyance direction (arrow a) of the continuous heating furnace (
1) The gap and mark on the back side of the cast iron/steel piece (3) generated in 1) are perpendicular to the roll row (10),
This is because the continuous heating furnace (10') is in constant contact with the skid mark, making it difficult to uniformly heat the entire skid mark with the lower burner (8b) described later.
This is because the total length of the furnace in which the roller hearth furnace (9) is connected becomes extremely long, which is not desirable in terms of equipment.

Each roll (10') constituting the roll row (10) is driven by a chain or sprocket wheel or the like and can rotate in both forward and reverse directions.

During heating in the roller hearth furnace (9), the roll row (1
Repeat the forward and reverse rotation operation of 0) to remove the cast iron/steel piece (3
) is constantly moved forward and backward as shown by the arrows to prevent skid marks from coming into contact with the roll row (10).

As shown in Figure 1 (c), the roller hearth furnace (9) is provided with burners (8a) (8b) for heating the cast iron/steel pieces (3) at the upper and lower parts sandwiching the roll row (10). ing.

The upper burner (8a) is for heating, uniformly heating, or retaining the upper surface of the cast iron/steel piece (3) to the required temperature.In the illustrated example, multiple burners are installed in the furnace length direction on the ceiling. A roof combustion system is used, in which two combustion engines are arranged in parallel at regular intervals. The lower burner (8b) is used to heat the lower surface of the cast iron/steel piece (3) and eliminate skid marks generated in the continuous heating furnace (1). Multiple units are installed at regular intervals in the direction, and a side combustion method is used.

The combustion methods of the upper burner (8a) and the lower burner (8b) are not limited to the methods illustrated above,
Alternatively, an axial combustion method, a side combustion method, or the like may be used for the upper burner (8a), and an axial combustion method, etc. may be used for the lower burner (8b).

When the skid marks on the cast iron/steel piece (3) are erased by heating with both the upper and lower burners (8a) (8b), the cast iron/steel piece (3) is transferred to the roller hearth furnace (9) through the extraction port (9b). Carry it outside.

Next, examples will be described.

(Example) According to the present invention, a cast iron/steel piece preheating furnace as shown in FIG. 1 was manufactured. In other words, the continuous heating furnace (1) has a total length of 3
311 roof combustion type walking beam heating furnace, roller hearth furnace (9) has 250 rolls above the roll row (10).
The furnace length was set to 25 m so that two slabs of mm thickness x 1, 000 mm width x 10,000 mm length were always present, and a total of 50 upper burners (8a) were arranged in parallel at regular intervals on the ceiling. The roof combustion method is changed to the lower burner (8
For b), a side combustion method was adopted in which a total of 50 units were placed at regular intervals on the side wall of the furnace.

FIG. 2 shows the roller hearth furnace according to the present invention,
This is an example of a study of the reduction in skid marks per hour of the slab's time in the furnace. In other words, if the deviation between the thickness center temperature of the skid mark part of the slab and the thickness center temperature of the normal part of the slab on the exit side of the walking beam furnace is 100°C, the deviation will be reduced to 7°C after one hour of use in the roller hearth furnace. Which indicates that.

In the heating furnace of the present invention, 250 m5 + thickness x l
, 000n+m width x 10.000m+m length several slabs were heated in a walking beam furnace for 3.5 hours to reach an average temperature of 1,200°C, and then placed in a roller hearth furnace so that two slabs were always present. The operation was carried out with a furnace time of 15 minutes. As a result, the thickness center temperature of the skid mark part of the slab on the exit side of the walking beam furnace was 111
5℃, while the thickness center temperature of the normal part of the slab was 1185℃, and there was a difference of 70℃ in temperature deviation between the two, but when extracted from the roller hearth furnace, the above temperature deviation was 30℃.
It was found that the temperature was further reduced to 15°C after rough rolling.

On the other hand, when a slab similar to the above was heated in a walking beam furnace for 3.5 hours and rough rolled at 1,200°C without being passed through a roller hearth furnace, the skid marks and normal parts were separated. It was found that the temperature deviation was 35°C, which was more than double that of the heating furnace of the present invention.

(Effects of the invention) As explained above, the cast iron/steel piece heating furnace of the present invention has the following features:
This method reduces the skid marks that occur on cast iron and steel pieces due to heating in a continuous heating furnace by reheating them in a roller hearth furnace. As shown in the examples of countermeasures, the function is not affected by various furnace operating conditions such as differences in furnace time and weight differences between cast iron and steel pieces, and skid marks can be effectively reduced at all times. .

In addition, it can be easily modified from any type of continuous heating furnace such as a pusher set, walking beam type, walking hearth type, etc., and has advantages such as simple structure and high durability.

[Brief explanation of the drawing]

FIG. 1 is a diagram illustrating an example of a cast iron/steel piece heating furnace according to the present invention, in which (a) is a vertical cross-sectional side view, and (b) is a diagram of FIG. 1 (a).
(C) is a partial sectional view taken along the line A-A in FIG. 1 (A), and FIG.
Graph showing the relationship between steel single furnace time and reduction of skid marks, Figure 3 is a cross-sectional side view in the width direction of a pusher set processing furnace, Figure 4 is a cross-sectional side view in the width direction of a walking beam two heating furnace, Figure 5 The figure is a longitudinal cross-sectional side view in the width direction of a walking hearth type heating furnace. 1: Continuous heating furnace, 8a: Upper burner, 8b: Lower bar, 9: Roller hearth furnace, 1O2 roll row Applicant
Sumitomo Metal Industries, Ltd. - Representative Patent Attorney Moto Namagata Senior Representative Patent Attorney Yoshi 1) Sho 2 Figure 1 (a) (b) Figure 2 Figure 35i! ! Figure 5

Claims (1)

[Claims] (1) The above-mentioned cast iron/steel pieces are conveyed so as to be rotatable forward and backward in a direction orthogonal to the conveying direction of the cast iron/steel pieces in the above-mentioned heating furnace, in contact with the outlet side of a continuous heating furnace having a cast iron/steel piece conveying equipment in the furnace. A heating furnace for cast iron and steel pieces, characterized in that a roller hearth furnace is provided with a row of rolls for heating and heating burners at the upper and lower portions of the furnace sandwiching the row of rolls.