JPS60213383A - Continuous joining method of high-temperature thick steel plates - Google Patents

Abstract

PURPOSE:To improve productivity in rolling operation by pouring a high-temp. molten steel into the space formed of the ends of preceding and succeeding billets and copper straps and cooling said steel to solidify on a heat resistant traveling belt then subjecting the billets to continuous rolling. CONSTITUTION:A clearance W is maintained between the high-temp. billets 1 and 2 on the heat resistant traveling belt 8 and the apertures on both sides in the transverse direction are closed by water-cooled copper straps. The molten steel 3 is poured from a vessel 7 for the molten steel into the space formed of the rear end of the preceding billet 1, the front end of the succeeding billet 2 and the copper straps. The vessel 7 is removed upon completion of pouring. The billets 1, 2 are transferred on the belt 8 and the molten metal 3 cools to solidify, thus forming a joint layer 4. The billets 1, 2 joined via the layer 4 are conducted to rolling rolls by the belt 8 and are successively rolled to a product. Since the joining is completed simply by pouring and cooling of the molten steel, the productivity in the rolling operation is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for joining steel materials, and more particularly relates to a method for joining thick steel materials to be joined between a preceding steel billet and a following steel billet in a continuous hot rolling process of steel materials. .

Conventionally, when hot rolling steel materials, steel slabs of a predetermined length are usually intermittently supplied one by one to a rolling mill for rolling. In this case, the tip and rear ends of the steel billet will have a defective shape and will be cut off, resulting in a poor product yield p.)
In addition, every time the end of the steel piece gets caught in the roll or is ejected from the roll, an impact load is applied, which increases the chances of roll flaws, resulting in roll replacement costs and rolling stoppages for roll replacement. The time loss was a problem. Therefore, if multiple pieces of steel are connected in advance and rolled continuously, the above problem will not occur and productivity will be improved. It is conceivable that this can be significantly improved.

Generally, when continuously cold rolling relatively thin steel plates (initial thickness 10+w+ or less), a method of connecting the steel materials using flash butt welding or the like shown in Figure 1 is used. In the hot rolling process, the welding equipment capacity is insufficient because the plate is thick (initial plate thickness 30 to 20 cm), and it is difficult to join the entire cross section in a short time using such a method.

Therefore, as shown in Fig. 2 and Fig. 3, the end molds of the front and rear steel pieces were fitted together, and the rivet 7C was temporarily fixed by driving a nail-like material or welding. There is a method of pressure welding with rolls, etc., but these methods are almost impossible to use for thick steel pieces with a thickness of 50 mm or more, and even in the case of a plate thickness of 30 to 50 mm, the overlapped part cannot be made long. 100m or more), and this part is required for a special pre-rolling process that is different from the normal part.Furthermore, these joint parts are ultimately cut off and scrapped, so the longer the joint part, the worse the product. There was also the drawback that the yield of For this reason, there has been a strong demand for the development of a technology that can connect and continuously hot-roll thick steel slabs with an initial thickness of 30 to 250 mm with high efficiency and low cost.

In view of the above-mentioned conventional problems, the present invention provides a method for joining thick steel materials, which can join thick steel pieces with a simple process and with high efficiency, and which can also achieve a perfect joint. In the hot continuous rolling process of steel billets in which multiple steel billets are continuously rolled, the trailing end of the leading billet and the tip of the trailing billet are placed on a heat-resistant running belt. Installed at a predetermined interval t, one water-cooled copper dowel is pressed outward into the openings on both sides of this gap, and the rear end of the preceding steel piece is pressed.

All of the high temperature molten steel is injected into the space formed by the copper dowel at the leading end of the trailing billet, the molten steel is cooled and solidified while running on the belt, and after 1c, the billet is fully continuously rolled. do.

Hereinafter, details of the method of the present invention applied to the drawings will be explained.

Figures 4 and 5 show the entire situation in which the method of the present invention is carried out. Figure 4 is a side sectional view during injection and cooling of molten steel, Figure 5 is a plan view of the same, FIG. 6 is a side sectional view during rolling. The hot steel pieces 1 and 2 are placed on a heat-resistant running belt 8 and moved. At this time, a gap NW is maintained between the rear end portion of the leading steel piece l and the tip end of the trailing steel piece 2. The openings on both sides of the gap W in the width direction of the steel strip are closed with copper pads 9. This deposit 9 becomes a water jacket, and the cooling water 10 is L! ll is cooled, and is pressed outward in the width direction of the steel piece with a force of Fl.

In this state, while moving the leading steel slab 1, the trailing steel slab 2, and the heat-resistant traveling belt 8, the gap W, that is, the rear end of the leading steel slab 1, the tip end of the trailing steel slab 2, and the Machined copper dowel 9
The molten steel 3 is injected into the space formed in the hole. This molten copper 3
is injected from a molten steel container 7ρ) set above the space and containing six volumes of high-temperature molten steel. The molten steel container 7 has a refractory lining and is equipped with a stopper on the lower molten steel pouring nozzle (not shown). It will be done.

In the figure, 5 is the slag floating on the surface of the melt 9143.

When the injection of molten steel 3 is completed until it fills the space, the molten steel container 7 is removed, and the steel slabs 1 and 2 are placed on the heat-resistant running belt 8.
#gI 143 is transferred to the threshold and cooled and solidified to form a bonding layer 4, and the leading steel piece 1 and the trailing steel piece 2 are in a state of being joined via this bonding layer 4. In this state, steel piece 1
, 2 are further conveyed by a heat-resistant running belt 8 to the rolling roll 1.
1 and rolled to a plate thickness of 10ρ1 to 11, and then sequentially passed through a group of rolling mills on the downstream side (not shown) to be continuously rolled into products such as thin plates. Note that 12 is a heat-resistant running belt drive roller.

Generally, when hot rolling steel billets, the plate thickness is 200 mm for slabs.
~250 wa, the bar (30~5° for D) is heated to about 1150°C for slab and 1000°C for par.
, 2 (end faces of 2) in advance with high-pressure water, etc., and then spray a reducing agent or flux on the surface and then inject molten steel as described above, the molten steel 3 The generated slag 5 contacts the surface of the joint while blocking the atmosphere, and a portion of the steel slabs 1 and 2 melts due to the retained heat. Then, as mentioned above, the molten steel 3 cools and solidifies, and the steel slab 1゜2 becomes the joint rt where the bath 94I43 has solidified.
They will be joined via ti4*. In addition, the well-known -q acid, silicate soda, etc. are used for the above-mentioned flux.

In addition, in the above process, since contraction occurs when the molten steel solidifies, a force Fzk is applied to the rear blade 1 of the trailing steel piece 2 to press it. Next, after the molten steel 3 has cooled and solidified, the copper dowel 9 is removed, and the steel slabs 1 and 2 are fed to the rolling rolls 11 and continuously rolled. The slag 5 remaining on the upper and outer surfaces of the slab is removed by a descaler (not shown).The CFI in Figure 6 shows the rolling status of the preceding slab 1, and (b) shows the rolling status of the preceding slab 1. shows the rolling status of the trailing steel billet 2 after passing through the rolling rolls 11.

Examples〉 A slab with a thickness of 250mm and a width of 1000mm and a bar with a thickness of 50m and a width of 1000mm were used as specimen steel pieces, and a joining test of the steel pieces was conducted using the method according to the present invention. We investigated and examined the bonding conditions when the temperature and the gap W between the steel pieces were varied.

The results are shown in &Table.

Based on the results of this test, poor joining will occur if the temperature of the molten steel is low or the gap is narrow, and conversely, if the gap is too wide, cracks due to shrinkage or problems such as a prolonged solidification time will occur.
Continuous rolling becomes impossible. (Incense 1, 5, 6.10) L
However, molten steel temperature and gap? When properly applied, a good bonding state was obtained and continuous rolling was possible. (Incense 2, 3
, 4, 7.9) Thus, appropriate molten steel temperature and gap W [
It has been proved that it is possible to join high-temperature steel billets with high efficiency and carry out continuous rolling according to the present invention.

It is clear from the above explanation that η≧, and the method of the present invention is applied to the heat-resistant running belt for a predetermined period of time. This is a method to join thick steel pieces by injecting molten steel between two steel pieces and solidifying it, and the ends of the steel pieces must be formed into a special shape before joining. There is no problem at all, and joining can be completed simply by injecting molten steel and cooling, making it possible to join billets with extremely high efficiency, which greatly contributes to improving the productivity of rolling operations. Furthermore, since continuous hot rolling equipment is generally installed close to a steelmaking factory, the method of the present invention can be carried out advantageously in terms of cost by utilizing leftover hot water from steelmaking ingot operations. .

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing a method of joining steel plates, Figs. 2 and 3 are explanatory diagrams showing a conventional method of joining steel plates, and Fig. 4 is a side sectional view of molten steel injection and cooling according to the method of the present invention. FIG. 5 is a plan view of the same, and FIG. 6 is a side sectional view during rolling. In the drawing, 1 is a leading steel piece, 2 is a trailing steel piece, 3 is molten steel, 4 is a bonding layer, 7 is a molten steel container, 8 is a heat-resistant running belt, 9 is a copper dowel, 10 is a cooling water, 11 is a rolling It's a roll. Patent applicant: Mitsubishi Heavy Industries, Ltd. Patent attorney: Shibu Mitsuishi (and 1 other person)

Claims (1)

[Claims] In the continuous hot rolling process of steel billets in which a plurality of steel billets are continuously rolled, the rear end of the leading steel billet and the tip of the trailing steel billet are all placed on the heat-resistant running belt with a certain gap, Attach water-cooled copper dowels to the openings on both sides of this gap, and pour high-temperature molten steel into the space formed by the copper dowels at the rear end of the preceding steel piece and the tip of the trailing steel piece. A method for continuously joining high-temperature thick steel materials, characterized in that the molten steel is injected, cooled and solidified while traveling on the belt, and then the billet is continuously rolled.