JPS6111145B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing so-called beam blanks, which are used as materials for long steel, on a continuous casting line, and more specifically relates to a method for producing a so-called beam blank as a material for long steel, and more specifically, a method for producing a beam blank that is cast into a normal shape without using a special mold. This invention relates to a method for forming beam blanks in-line.

Beam blanks are generally produced by forming a steel ingot by a so-called ingot-forming method and then subjecting it to blooming and rolling. However, as is well known, the ingot forming method is disadvantageous in many other respects, such as yield, cost, and efficiency, as well as efficiency, compared to the continuous casting method.

As an example of applying the continuous casting method to the manufacture of beam blanks, there is a method of directly drawing beam blanks using a special irregularly shaped mold as shown in the plan view of FIG. 1A. However, with this method, vertical cracks 2 as shown in Figure B frequently occur on both sides of the beam blank, especially at the joint 1 of the split mold, and in order to prevent this, the slab drawing speed has to be drastically reduced. The original high efficiency of continuous casting is lost. Moreover, in order to meet the requirements for different slab sizes, the only solution is to replace the molds, which requires preparing many molds for each size, which inevitably increases equipment costs.Moreover, mold replacement requires interruption of work. is the biggest cause of lower operating rates.

The present invention aims to provide a method for manufacturing a beam blank that solves the above-mentioned problems.

The present inventors previously discovered that as an alternative to changing the width of a slab in continuous casting, the slab was cooled at a position 4 in front of the cutting machine 3 shown in the continuous casting line in FIG. We proposed a method in which the slab is pressed periodically from both sides to reduce the slab to a predetermined width by a certain length. In this method, if a flat head 16 as shown in FIG. 6 is used as the pressing head, the slab will have a so-called dogbone shape in which the side ends are largely raised in the thickness direction.

The inventors of the present invention focused on this swelling phenomenon, and as a result of conducting various experiments and research on a method of forming the beam blank using this inversely, they found that if the shape of the slab pressing head is devised, the above We confirmed that it is possible to manufacture beam blanks by repurposing the width changing method.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

3A and 3B show an example of an apparatus for carrying out the method of the present invention, in which A is a longitudinal sectional front view and B is a cross-sectional plan view.

Reference numeral 5 denotes a housing which is provided in front of the cutting machine of the continuous casting line and houses a pressing head, and is moved forward or backward along guides 10, 10 parallel to the line by a hydraulic cylinder 6. 7
is a slab pressing device installed oppositely on the left and right sides of the housing 5, in which pressing heads 9, 9 each equipped with a hydraulic mechanism are provided so as to face both sides of the slab passing through the housing 5 and then retreat. It is being

The pressing process using the above device is performed as follows. First, as shown at 1 in FIG. 4A, both of the pressing heads 9, 9 are simultaneously fed out, sandwiching the slab 8 from both sides and pressing it to process it in the width direction. During pressing, the housing 5 follows the movement of the slab 8 and is self-propelled or driven (see 2 in the figure B).
). The pressing in step 1 is continued until the slab width is compressed to the target width. When the pressing is completed, the head 9 returns to its old position and the housing 5 is also returned to its previous position.

The above cycle is repeated in synchronization with the movement of the slab, and the slab is finished to a predetermined width at a constant length.

A feature of the present invention is that, as the pressing head 9, a head having the shape shown in FIGS. 5A and 5B is used. That is, the head 9 includes a recess 11 into which the side of the slab 8 fits, and the width t ₂ of the bottom surface 12 of the recess is t ₂ /t ₁ = 1.1 with respect to the thickness t ₁ of the slab.
1.6, and the concave portion 11 has a shape that widens vertically toward the open side with a taper angle of θ1 to 45°.

In the case of a flat head that does not have a recess, that is, there is no restriction on the expansion of the slab in the thickness direction during pressing, the slab is formed into a dogbone (see FIG. 6) as described above. However, in the present invention, the slab is provided with a recess that fits loosely, and the bottom surface 12 of the recess presses the side surface of the slab, and the upper and lower contact surfaces 13, 13
A beam blank can be obtained by creating a shape that appropriately suppresses the formation of dog bones. At this time, the expansion of the slab in the thickness direction is adjusted by the bottom width t ₂ of the recess 11, that is, by the size of the interval between the upper and lower contact surfaces 13, 13. Regarding the relationship between this t ₂ and the slab thickness t ₁ , it has been experimentally determined that the ratio t ₂ /t ₁ between the two can be set to 1.1 to 1.6 to meet all existing beam blank size requirements. was confirmed. Therefore
It was limited to t ₂ /t ₁ =1.1 to 1.6.

Also, the taper θ formed on the upper and lower abutting surfaces 13, 13 allows the head 9 and slab 8 to be tightly fitted together after pressing.
Not only does it play the role of a so-called punching allowance when separating the slabs from each other, but it also releases a part of the expansion force of the slab along the taper, reducing the pressing force P and removing the slab thickness that is about to expand. It works to smoothly push the beam blank toward the center and adjust the finished shape of the beam blank. According to the inventor's experiments, good results could be obtained by setting the taper angle θ to 1° to 45°. Therefore, the taper angle θ is limited to 1° to 45°. Note that the depth H of the recess may be determined to be a sufficient depth depending on the bulge of the slab.

On the other hand, when looking at the plan view in FIG. We are prepared. This moves the processed part 8 ₁ and the unprocessed part 8 ₃ pressed by the parallel part 14 to the curved part 1
This is to avoid extreme deformation due to the action of abnormal shearing stress by forming a shape in which the half-processed portion 8 corresponding to No. 5 is smoothly connected at ₂ . Therefore, the curved portion is provided so that its entrance end 15' does not overlap the slab side surface 18. In order to obtain a beam blank with a continuous and stable shape, it is also necessary to
It is important to set the length L to a length necessary for the machined parts ₈₁ to be continuous with appropriate overlap, based on the moving speed of the slab and the pressing cycle of the head.

Next, an example of implementing the method of the present invention in an actual continuous casting line is listed below.

Example 1 Regarding a continuous casting slab with a thickness of 130 mm and a width of 950 mm,
Above t ₂ /t ₁ = 300mm/230mm = 1.3, taper angle θ = 5
By using a head with a recess of 175 mm on one side according to the method of the present invention, a beam blank with a maximum thickness t ₃ (see Figure 5 A) of 350 mm and a width of 600 mm was stably produced. It was done.

Example 2 Continuously cast slab similar to Example 1 at t ₂ /t ₁ = 368
mm / 230 mm = 1.6, using a head with a concave portion of taper angle θ = 1°, and 175 mm on one side according to the method of the present invention.
When pressed, the maximum thickness _t3 was 369
Beam blanks with a width of 600 mm and a width of 600 mm were stably manufactured.

Example 3 Continuously cast slab similar to Example 1 at t ₂ /t ₁ = 253
mm/230mm=1.1, and a head equipped with a concave portion with a taper angle θ=45° was pressed to a depth of 88mm on one side according to the method of the present invention, resulting in a maximum thickness _t3 of 420mm.
A beam blank with a width of 774 mm was stably manufactured.

As is clear from the above explanation, the method of the present invention allows beam blanks to be manufactured on a continuous casting line without using special molds, and there is no need to reduce the line speed, so the high efficiency inherent to continuous casting can be achieved. In addition, it is possible to obtain products of extremely stable quality, and since it is possible to immediately respond to requests for various product sizes without replacing molds, there is no reduction in operating efficiency.

[Brief explanation of the drawing]

Figure 1A is a plan view of a mold used in the conventional continuous casting method for producing beam blanks;
Figure B is a perspective view showing vertical cracks that occur when manufacturing by the above method, Figure 2 is an explanatory diagram of the continuous casting line showing the installation position of the equipment in Figure 3, Figure 3 A,
B shows an example of an apparatus for carrying out the method of the present invention, in which A is a longitudinal sectional front view and B is a cross-sectional plan view. Figures 4A, 4B and 4C are explanatory diagrams showing a pressing cycle according to the present invention. FIGS. 5A and 5B show the shape of the pressing head used in the method of the present invention, where A is a front view and B is a cross-sectional plan view. FIG. 6 is a front view showing the dogbone shape of the slab. In the figure, 1: Joint, 2: Vertical crack, 3: Cutting machine, 5: Housing, 6: Hydraulic cylinder, 7: Pressing device, 8: Slab, 9: Pressing head, 10: Guide, 11: Recessed portion, 12: Bottom surface of recessed portion, 13: Upper and lower contact surfaces, 14: Parallel portion, 15: Curved portion, 1
6: Flat head, 17: Dog bone.

Claims (1)

[Claims] 1. A recess is provided that loosely fits into the side of the continuously cast slab that has undergone secondary cooling and is not yet cut, and the recess has a taper angle of 1 to
It expands vertically at an angle of 45 degrees, and its base width t ₂
A concave head with t ₂ /t ₁ = 1.1 to 1.6 for slab thickness t ₁ is pressed into the casting by a pressing device built into the housing that follows the movement of the slab and returns every time it follows a certain distance. A method for manufacturing a beam blank, characterized by forming a slab into a beam blank shape by periodically pressing from both sides of the slab.