JPS6344460B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a mold for continuous casting, and particularly proposes a mold structure that is effective in strengthening cooling, thereby avoiding manufacturing troubles such as breakouts, and significantly improving lifespan. It is something.

Figure 1 shows the outer end face of a conventional mold copper plate, and Figure 2 shows the overlapping structure of a conventional continuous casting mold between the copper plate 1 that occupies the side that contacts the molten steel and the back plate 2 that is located outside of the copper plate 1. It shows.

The feature of this conventional mold structure is that the back plate 2
and the copper plate 1 are connected by a tightening bolt 3 screwed into the copper plate 1 from the back plate 2 side. Therefore, in the part where this tightening bolt 3 is located, it is not possible to arrange water passage grooves 4 used for cooling the copper plate 1, and
Since a gap 5 is created between the tip 3a of the tightening bolt 3 and the bolt hole on the copper plate side, which creates a layer of air with poor thermal conductivity, a decrease in cooling efficiency was observed.

Figure 3 shows the distribution of the surface temperature of the nickel plating layer 10 of the conventional mold and the isotherm inside the copper plate, and it is clear that heat removal is poor mainly at the bolt screw head. I understand.

Such a phenomenon causes a local increase in the mold surface temperature and delays shell formation, making breakout more likely to occur. Furthermore, since the temperature of the mold copper plate locally increases, thermal distortion occurs in the copper plate, resulting in disadvantages such as shortening the casting life of the mold.

An object of the present invention is to advantageously overcome the poor cooling effect in the vicinity of the tightening bolt, which has been observed in conventional molds. For this purpose, the present invention provides the following features:
A group of water flow grooves that control forced cooling of the mold copper plate and horizontal grooves having the same groove depth are formed between adjacent water flow grooves. As a means of solving the above problem, we adopted a continuous casting mold in which welded stud bolts are attached to the back plate, which fixedly supports the overlapping mold copper plates. The details of the configuration will be explained below.

FIG. 4 is a sectional view showing the outer end surface, that is, the back surface of the mold copper plate of the invention, and FIG. 5 is a cross-sectional view showing the isothermal distribution of a part of the mold. ' is a back plate, and 4 is a water channel, which is bored in multiple strips on the mating surfaces of the copper plates 1, 1' with the back plates 2, 2', and when they overlap with the back plates, water cooling space is created. It has come to consist of

In the present invention, a plurality of stud bolts 6 are fixed to the copper plate 1 side in order to connect the copper plate 1 and the back plate 2. Specifically, a horizontal groove 7 having the same groove depth is provided in the copper plate 1 between adjacent water passage grooves 4, and the tip of a stud bolt 6 is fixed to the center of the deep side of the horizontal groove 7 by welding. However, the cooling water in the water passage groove 4 is made to flow into the lateral groove 7 to strengthen the cooling of this part.

The overlapping of the copper plate 1 and the back plate 2 is achieved by providing a bolt insertion hole 8 in the back plate 2 corresponding to the stud bolt 6, and using a threaded bolt head 6 that protrudes from the insertion hole 8 onto the surface of the back plate 2.
This is accomplished by screwing in the tightening nut 9 into a and tightly tightening both.

When such a structure is adopted, as can be seen from the isothermal distribution diagram in Figure 5, the cooling of the bolted part is significantly strengthened compared to the conventional mold, and the various problems with the conventional mold mentioned above are solved. Ru.

In addition, in the past, the tightening bolts 3 were screwed directly into the copper plate 1, so unless the copper plate 1 was at least 50 mm on the short side and 55 mm on the long side, the required screwing depth of 35 mm could not be obtained. Due to a problem, the copper plates 1 and 1' could not be made very thin. On the other hand, in the structure of the present invention described above, since there is no restriction on the screwing depth as described above, the copper plates 1 and 1' can be made thinner, and the water passage groove 4 can be brought closer to the molten steel side accordingly. Therefore, cooling can be strengthened. Moreover, by making the water passage groove 4 shallower, the flow rate of the cooling water will increase, heat removal will be improved, the formation and growth of shell will be promoted, the casting speed will be increased, and breakout will be prevented. do.

According to tests conducted by the present inventors, in the case of conventional molds, the breakout occurrence rate at the short side corners is approximately 0.5% (1 time/200 charges), and the occurrence rate of breakout marks is approximately 5% (5%). However, when the mold of the present invention was used, these were completely eliminated.

In addition, in the case of the mold of the present invention, vertical cracks in the slab were reduced, and the hot charge rate and casting speed were increased (1.4 m/min, 1.6 m/min).
In addition, we were able to improve this from 30% to 65%.

[Brief explanation of the drawing]

Fig. 1 is a broken end view of a conventional mold copper plate, Fig. 2 is a sectional view taken along the - arrow in Fig. 1, Fig. 3 is a partial sectional view of a conventional mold showing the isothermal distribution, and Fig. 4 5 is a broken end view of a copper plate mold of the present invention, and FIG. 5 is a partial cross-sectional view of the mold of the present invention, also showing the isothermal distribution. 1, 1'...Copper plate, 2, 2'...Back plate, 4...Water groove, 6...Stud bolt, 7...
... Bolt storage hole, 8 ... Bolt insertion hole, 9 ... Tightening nut, 10 ... Nickel plating.

Claims (1)

[Scope of Claims] 1. On the back side of a mold copper plate that forms a continuous casting mold, a group of water flow grooves for forced cooling of the mold copper plate and a groove depth extending between adjacent water flow grooves are provided. The same type of lateral groove is formed, and a stud bolt is fixed by welding at the center of the depth of the lateral groove for connection with a back plate which is overlapped with the back of the mold copper plate and fixedly supports the mold copper plate. Casting mold.