JPS59197301A - Flawless rolling method of billet cast by synchronous, rotary, continuous casting method - Google Patents

Abstract

PURPOSE:To prevent a rolling material from generating surface flaws caused by the turnups of pointed parts of the material by preforming the pointed parts into flat faces in rolling a continuously cast billet having a trapezoidal cross section cast by a synchronous, rotary, continuous casting method. CONSTITUTION:In rolling a cast billet 7 having a trapezoidal cross section, cast by a synchronous, rotary, continuous casting device, into finally a wire rod, etc.; the pointing parts 8 of the lower face (b) of billet 7 are turned up to the upper side during the rolling, and it causes surface flaws and deteriorates the quality of a product. In this case, before rolling the billet 7, the pointing parts 8 are preformed into the surfaces C of 5-15mm. by a flat preforming roll 10 or a grooved roll 11 equipped with a driving device 12, and then the billet 7 is rolled by plural rolling stands. Thus, a rolled product excellent in quality is obtained without generating the surface flaws caused by the turnups of pointed parts 8.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a defect-free rolling method for synchronously rotating continuously cast slabs, and specifically, the present invention relates to a method for rolling synchronously rotating continuously cast slabs, and specifically, a pointed p portion at the bottom of a continuously cast slab having a trapezoidal cross section (section 8 in Fig. 1). The purpose of this is to preform the material into a planar shape with no corners, and to prevent the occurrence of surface flaws due to folding of the sharp portion during subsequent rolling (shaping). In conventional synchronous rotary continuous casting, rolling of a continuously cast material with a trapezoidal cross section is carried out by rolling the corner (part 8 in Fig. 1) without preforming, as shown in Fig. 2.
The rolls 2 were combined and rolled and shaped into a predetermined size.

In the figure, I is 1 bus, 1Iti 2 passes, ■ is 3 passes,
IV indicates 4 passes.

However, in this conventional method, due to the difference in stretching between the upper and lower surfaces (planes a and b in FIG. 1) of the trapezoidal section of the continuous slab 3, the 8th section in FIG. 1 is bent upward due to rolling, and the surface This could have been a cause of defects.

By the way, when the final product is made into high-grade wire rods, surface defects are strictly controlled, and in order to eliminate them as much as possible, inspection and eaves removal 9.
A great deal of effort has been put into it.

Therefore, for steel manufacturers aiming at producing high-grade steel, it is essential to eliminate scratches that occur during the rolling (forming) process. Therefore, careful consideration should be given to the shape of the roll hole, reduction distribution, number of roll baths, etc. Consideration has been taken. Similarly, there was a strong desire for defect-free rolling of continuously cast materials with trapezoidal cross sections.

In order to solve such problems, the present invention has been developed by preforming the pointed portion of the slab before rolling the slab having a trapezoidal cross section cast by synchronous rotation continuous casting. A defect-free rolling method for a synchronously rotating continuously cast slab, characterized in that the slab is rolled into a planar shape by rolling it into a planar shape, and in claim 1,
Further, there is provided a method for defect-free rolling of a synchronously rotating continuous casting piece, characterized in that the total amount of preforming is 5 to 15 m1n.

The present invention will be fully explained below based on embodiments shown in the drawings.

That is, as shown in FIG. 3, the present invention sets a vinyl preforming device 6 upstream of a row of continuous casting material rolling mills 5 in the downstream process of a synchronous rotary continuous casting device 4, and continuously casts a trapezoidal cross-sectional shape. The pointed portion 8 of the material 7 is preformed.

As shown in FIG. 4, this vinyl roll type preforming device 6 is equipped with a straightening roll 9 for preventing the continuously cast piece 7 from bending upward. The preform roll 10 may be a flat roll or a slotted roll 11 as shown enlarged in FIG. Note that 12 in FIG. 4 is a drive device for the preforming roll.

This preforming device 6 is installed just before the rolling mill row 5 and is used as a series of equipment. Alternatively, the preforming device 6 can also be used as a guide without driving, that is, as a guide type preforming device 6.

The amount of preforming (C in FIG. 6) may be between 5 and 15. If the preforming i,'t- is made too large, it is undesirable because it will lead to wear of the preforming roll 10, increase in power cost, etc. If the amount of preforming C is less than 5, the effect will be small and the frequency of occurrence of folding defects will increase.

Prevention of flaws by preforming will be explained in Examples.

The tip 9 portion 8 of the mold cross section shown in FIG. 7(0) was preformed as shown in FIG. 7(b). The amount of preforming (e) was varied from 0 to 15 mm. This material was rolled into a rectangular cross-section with a V-roll at a stretch of approximately 1.31 as shown in FIG.

The entire area where folding defects occur is shown in FIG. When the preforming amount C was 0, the tip 9 portion 8 was bent, resulting in surface flaws. However, when the preforming amount C was 5 g or more, no folding defects were observed.

As described above, according to the present invention, when a continuously cast material having a trapezoidal cross-sectional shape is produced, by eliminating corners by preforming, the occurrence of folding defects can be prevented and defect-free rolling has become possible.

Therefore, the present invention has industrially beneficial effects such as being able to manufacture rolled wire rods of good quality.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing a continuously cast slab with a trapezoidal fclfr surface obtained by a synchronous rotary continuous casting machine, Fig. 2 is an explanatory diagram showing the conventional rolling method, and Fig. 3 is an explanatory diagram showing the rolling method of the present invention. Explanatory diagram,
FIG. 4 is an explanatory diagram showing an enlarged view of the main parts of the preforming apparatus in FIG. 7th cross-sectional view of continuous slab of
Figures G) to C→ are explanatory diagrams showing the main parts of FIG. 3 in an enlarged manner and the test method of the present invention, and FIG. 8 is a graph showing the amount of preforming and the amount of folding defects. 1: V roll, 2: H roll, 3: Continuous casting piece, 4: Synchronous rotation continuous casting device, 5: Continuous casting material rolling mill row, 6: Vinci roll preforming device, 7: Continuous casting material (continuous ( 5) Slab), 8: Pointed part, 9: Straightening roll, 1o: Preforming roll, 11: Hole shape a-ru (preforming roll), 12:
Drive device for preforming rolls. Patent Applicant Nippon Steel Corporation (6) 1st time a Figure 2 I If vr
w bud 3rd 4th figure 5th 6th liang 7 mon (ri (ro) (c)
稟8 Figure preforming amount (mm)

Claims (2)

[Claims] (1) Synchronous rotation characterized in that when rolling a cast slab with a trapezoidal cross-sectional shape cast by synchronous rotation continuous casting, the pointed portion of the slab is preformed into a planar shape before rolling. Defect-free rolling method for continuously cast slabs. (2) The method according to claim 1, wherein the amount of preforming is 5 to 15111.