JP2003053489A - Width changing device in thickness changeable type continuous casting mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prolong life of a bellow type protection tube in a cylinder rod used to a width changing device in a continuous casting mold where the thickness of a cast slab can be changed. SOLUTION: In the width changing device in the continuous casting mold provided with a stepping cylinder for changing the width to change the thickness of the cast slab, at the outside of the stepping cylinder and the cylinder rod, the bellow type protection tube which has a portion having a different outer diameter size in the axial direction and the outer diameter in a portion positioned at the interval between the long side frames of the mold set smaller than the minimum thickness of the cast slab, is fitted instead of the conventional bellow type protection tube having the fixed outer diameter.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for changing the width of a continuous casting mold having a width changing stepping cylinder capable of changing the thickness of a slab, and more particularly to a stepping apparatus. A cylinder rod protection structure is proposed. [0002] Conventional slab continuous casting molds are generally of the type having a constant slab thickness and a variable width. That is, this type of mold is composed of a pair of fixed long side frames and a pair of short side frames between the frames and moving to change the width. Such molds correspond to the casting of slabs of various widths by sequentially changing the interval between the short side frames, that is, the width of the mold, according to the order width of the product. [0003] These continuous casting molds are generally set to a maximum width at the start of casting in order to prevent a breakout, and thereafter, usually, are successively reduced in accordance with an ordered slab width. Such a change in the mold width is performed by moving the left and right short side frames in the width direction using a width changing stepping cylinder installed on the back side of the short side frame and connected to the short side frame. ing. FIG. 1 is a schematic side view of a conventional moving device for a short side frame of a fixed thickness continuous casting mold. The short side frame 1 is composed of a copper plate 1a on the side (inside) in contact with the molten metal and a steel frame 1b on the outside thereof. Cooling water flows between the copper plate 1a and the steel frame 1b. The frame 1b is connected to a rod tip of a stepping cylinder 2 for changing a slab width by a pin 3b by a clevis portion 3 protruding from an outer surface of the frame 1b. The cylinder rod portion 2a of the stepping cylinder 2 is covered with a bellows-shaped protection tube 4 that can cope with the expansion and contraction of the cylinder rod, including the clevis portion 3 if necessary. The protection tube 4 is used to protect against bad environments such as heat from the surroundings, dust such as mold powder powder and iron powder, and steam from spray cooling. [0005] Now, in the case of a conventional fixed thickness continuous casting mold,
When changing the thickness of the slab, the entire mold was replaced as a set. For this reason, there is a problem that a long time is required for the mold replacement operation and a long downtime of the equipment, which leads to a decrease in production efficiency. As a method for solving this problem, a continuous casting mold has been developed in which the thickness of the slab can be changed by replacing only the short side frame. As will be described in detail later (FIG. 2), the mold can be replaced with a short side frame. After the short side frame is replaced,
Since the thickness can be changed only by moving the long side frame in the thickness direction, the working time can be significantly reduced as compared with the above-described technique of replacing the entire mold. [0007] As described above, the width of the mold is changed by moving the short side frame in parallel via the stepping cylinder. At this time, since a large load is applied to the stepping cylinder, the stepping cylinder is designed to sufficiently withstand such a load. However, in a continuous casting mold in which the thickness of a slab can be changed, the load applied to the above-described stepping cylinder is greatest when the thickness of the slab is maximum. Therefore, regarding the rod diameter of this stepping cylinder,
It is designed to withstand this maximum load. For this reason, the rod diameter of the variable thickness continuous casting mold is inevitably large, and as a result, the difference between the diameter of the cylinder rod portion and the interval between the long side frames (that is, the casting thickness) is relatively small, The installation space of the protection tube was restricted. That is, the protective tube needs to have a large difference (ie, thickness) between the inner diameter and the outer diameter of the bellows in order to secure the amount of expansion and contraction. The dimensions were inevitably large. for that reason,
Even if you try to attach the protection tube to the cylinder rod, there is almost no difference between the outside diameter of the protection tube and the distance between the long side frames. Sometimes contacted the side frame. As a result, the protective tube is worn or broken, and its useful life is reduced. As a result, there is a problem that the merit of employing the variable thickness mold is not fully utilized. An object of the present invention is to provide a continuous casting mold in which the thickness of a slab can be changed so that the contact between the bellows-like protective tube covering the cylinder rod and the long side frame can be maintained even in the state of the minimum casting thickness. An object of the present invention is to provide a width changing device for avoiding the above problem and realizing a longer life of the protection tube. [0011] The inventor of the present invention employs a protection tube having portions having different outer diameters in the axial direction instead of the conventional bellows-shaped protection tube having a constant outer diameter. As a result, the inventors have found that the above problems can be solved, and have completed the present invention. That is, the present invention relates to a continuous casting mold width changing device having a stepping cylinder for changing the width of a slab in a mold whose width can be changed. And a bellows-shaped protective tube having an outer diameter of a portion located between the long frames of the mold smaller than a minimum thickness of the slab is attached to the width changing apparatus of the variable thickness continuous casting mold. An embodiment of the present invention will be described below. FIG. 2 is a schematic side view of the continuous casting mold width changing apparatus according to the present invention, in which the thickness of the slab can be changed. This shows a state where the width is maximum (that is, a state where the stepping cylinder 2 is contracted). The stepping cylinder 2 includes a clevis 3a protruding from an outer surface of a steel frame 1b and a pin 3b at a tip end of a cylinder rod.
Thus, it is connected in a plug-in manner from above, and can be replaced in a short time. To protect the stepping cylinder 2 and its cylinder rod 2a, a bellows-like protection tube 4 is fitted so as to cover the outside thereof.
The bellows-shaped protective tube 4 has a small-diameter portion 4a on the free end portion which may interfere with the long side frame, and a large-diameter portion 4b on the other portion (up to the stepping cylinder outer cylinder portion). It has a multi-stage structure. Incidentally, in the protection tube 4 in the illustrated example, the outer diameter of the small diameter portion 4a is 200 mm, and the inner diameter of the large diameter portion 4b is 215 mm. FIG. 3 is a schematic diagram when FIG. 2 is viewed from above. As can be seen from this figure, when the interval A between the long side frames 5 is minimum, there is almost no difference between the outer diameter B of the outer cylindrical portion of the stepping cylinder 2 and the interval A between the long side frames. By the way, in the case of the illustrated example, the distance A between the long side frames (the minimum thickness of the mold) is 220 mm, and the outer cylinder diameter B of the cylinder is 2 mm.
10 mm. That is, such a long side frame interval A
It can be seen that it is indispensable to form the protective tube in a multi-stage shape in the axial direction under the relationship between and the outer cylinder diameter B of the stepping cylinder 2. Next, FIG. 4 shows a state in which the casting width is reduced from the state shown in FIG. 3, that is, a state in which the cylinder rod 2a is extended. The bellows-shaped protective tube 4 is also extended, and its small diameter portion 4a enters between the long side frames. However, in this example, the difference between the outer diameter of the small diameter portion 4a and the interval A between the long side frames is
Since the length is 20 mm, the small diameter portion 4a of the protection tube and the inner surface of the long side frame 5 do not come into contact with each other. Protection tube small diameter section 4a
Must be at least about 10 mm. However, if this difference is increased, the thickness of the protection tube must be reduced, and the expansion and contraction distance of the protection tube 4 cannot be obtained. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS By adopting the bellows-shaped protective tube of the present invention as described above in a width changing device of a variable thickness continuous casting mold, even when the thickness of a slab is minimized, the protective tube and the long side are reduced. Contact with the frame can be avoided, the width changing operation can be performed smoothly, and the life of the protection tube can be extended. By the way, in this embodiment, the time required for the short side frame replacement work including the bellows replacement could be reduced from about 2 hours to ten and several minutes. Furthermore, the life of the protective tube (the number of uses) was very short, that is, 80 charges in the number of casting charges when the conventional width changing device was used, but the width changing device of the present invention was used. If it is 20
A remarkable extension of the service life of at least 00 charges has been obtained. As described above, according to the present invention,
As a protective tube for a telescopic cylinder of a continuous casting mold width changing device capable of changing the thickness of a slab, a portion having a different outer diameter dimension in the axial direction is used instead of a conventional bellows-shaped protective tube having a constant outer diameter. In addition, by using a bellows-shaped protection tube with the outer diameter of the portion located between the mold long side frames smaller than the minimum slab thickness, it is possible to greatly improve the number of service times of the protection tube. In addition, an improvement in productivity can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of a conventional continuous casting mold width changing device of a casting thickness fixed type. FIG. 2 is a side view of a continuous casting mold width changing device having a variable casting thickness. FIG. 3 is a plan view of a continuous casting mold width changing device having a variable casting thickness. FIG. 4 is a plan view of the width changing device in a cylinder rod extended state. [Explanation of reference numerals] Short side frame 1a. Copper plate 1b. 1. steel frame Stepping cylinder 2a. Stepping cylinder rod3. Connection part (clevis part) Bellows protection tube 4a. Bellows protection tube small diameter part 4b. 4. Large-diameter part of bellows-shaped protective tube Long side frame A. B. interval between long side frames Stepping cylinder outer cylinder outer diameter

Claims (1)

Claims 1. An apparatus for changing the width of a continuous casting mold comprising a stepping cylinder for changing the width of a slab in a mold having a variable width, the stepping cylinder and the outside of the cylinder rod. And a bellows-shaped protective tube in which an outer diameter of a portion located between the long side frames of the mold is smaller than a minimum slab thickness.