JP7222282B2 - Method for repairing converter furnace body shell - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for repairing a shell of a converter furnace body.

A converter is a facility that refines and removes impurities such as silicon and carbon contained in hot metal by blowing a reactive agent using an acidifying gas such as air or oxygen and a carrier gas such as nitrogen into the hot metal. is.
The inner surface of the converter furnace body is lined with refractory bricks that can withstand the heat generated by the molten iron and the refining reaction. The material and strength gradually deteriorate due to creep deformation and the like, and deformation progresses. If the deterioration of the material and strength of the furnace shell progresses, the furnace shell will crack, and in the worst case, dangerous accidents such as furnace body cracks and hot metal outflow will occur. Further, if the deformation of the furnace body progresses, interference occurs due to contact between the furnace support structure (trunnion ring) and the steel shell of the furnace body, which may cause the furnace body to fall off. Therefore, although it depends on the deterioration of the furnace shell and the operating conditions, the furnace shell is repaired after about 5 to 10 years from the start of operation to prolong its life.

For example, in Patent Document 1, the deteriorated peripheral part of the steel shell of the converter is cut into a rectangular shape with a corner having a curvature of about 2 to 5 times the thickness of the steel shell and a side of 300 to 3400 mm. A method for repairing a deteriorated converter furnace shell is disclosed, which removes the shell and attaches a new shell to the cut line removal trace and welds it.

Japanese Patent No. 2936072

However, although it depends on the degree of deterioration and the range of deformation of the steel shell, in the case of the method described in Patent Document 1, the area around the deterioration is cut in a rectangular shape so that the deteriorated part of the steel shell is completely included, so the repair range is widened. , the construction period is lengthened and the cost increases. During the repair work period, the operation of the converter will be stopped and repair work will be carried out.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for repairing a shell of a converter furnace body, which can shorten the construction period and reduce the cost as compared with the conventional methods.

In order to achieve the above object, the present invention is a method for repairing a locally deformed shell of a converter furnace, characterized by comprising the following steps.
(1) A step of removing the refractory lining on the inner surface of the converter furnace body to expose the steel shell of the converter furnace body (2) Installing a three-dimensional measuring device in the converter furnace body and Step (3) of measuring the shape of the furnace body shell; Step (4) of calculating the difference between the measured value of the shape of the converter furnace body shell and the shape design value to determine the deformation amount of the converter furnace body shell; ) The amount of deformation in the peripheral area including the deformed portion of the steel shell of the converter furnace body to be repaired is represented in a contour diagram, the contour line to be the cutting line is determined, and the three-dimensional coordinate value of the contour line to be the cutting line is displayed on the projector. Step (5) of inputting (5) setting the projector in the converter furnace body and irradiating the cutting line to the inner surface of the steel shell of the converter furnace body to mark the cutting line (6) marking line A step of cutting the steel shell of the converter furnace body along and welding a new steel shell to the cut location

In Patent Document 1, the repair range of the steel shell of the converter furnace body (hereinafter simply referred to as "shell") is rectangular. In order to reduce the repair range, if the rectangular repair range is reduced, as will be described later, the steel shell will be cut across the contour lines of the amount of deformation, and the cut surface and the new steel skin will not match. It gets worse (stepped). If the texture is poor, stress concentration will occur at the weld between the cut surface and the new steel shell, and cracks and fractures may occur in the weld in a short period of time. It is generally said that it is difficult to predict the remaining lifespan of weld cracks, and deterioration in contact with the weld may impair the effect of extending the lifespan of repairs.

In the present invention, by cutting and removing the deformed portion of the steel shell along the contour lines of the amount of deformation, it is possible to ensure good contact between the cut surface and the new steel shell. As a result, it is possible to significantly reduce the repair range while maintaining the same or better texture matching than in the case of a large repair range as in the prior art.

In the method for repairing the shell of a converter furnace body according to the present invention, by cutting and removing the deformed shell along the contour lines of the amount of deformation, it is possible to shorten the construction period and reduce the cost compared to the conventional method. As a result, it is possible to enjoy the production benefits of the early start-up of the converter.

1(A) is an elevational view of a converter furnace body to which a method for repairing a shell of a converter furnace body according to an embodiment of the present invention is applied; FIG. 1(B) is a plan view of the converter furnace body; (A) A plan view of the converter furnace body obtained by superimposing the shape actual measurement value and the shape design value of the iron shell, (B) an elevation cross-sectional view of the converter furnace body. FIG. 4 is a contour map showing the amount of deformation of a peripheral region including a deformed portion of the shell; It is a graph which represented typically the surface alignment of the cut surface and a new steel shell in each cutting line. (A) A plan view of a converter furnace body in which a projector is installed, (B) A vertical cross-sectional view of the same converter furnace body. It is a shape diagram of a scribe line drawn on the inner surface of the steel shell.

Next, an embodiment embodying the present invention will be described with reference to the attached drawings for understanding of the present invention.

A converter furnace body 10 (hereinafter simply referred to as "furnace body") to which a method for repairing a steel shell of a converter furnace body according to an embodiment of the present invention is applied is shown in FIGS. show. The furnace body 10 has a bowl-shaped furnace bottom portion 10a, a cylindrical straight body portion 10b, and a narrowed portion 10c whose diameter is reduced toward the furnace opening 10d, and an iron shell (converter furnace body It is roughly composed of an iron shell 13 and a refractory (not shown) arranged on the inner surface side of the iron shell 13 . A trunnion ring 11 having a pair of trunnions 12 supporting the furnace body 10 in a tiltable manner is mounted on the straight body portion 10b. The vicinity of the drawing start portion, which is the boundary region between the straight body portion 10b and the drawn portion 10c, is reinforced with a plurality of ribs 15, and a tapping port 14 extending outward is provided.

As shown in FIGS. 1(A) and 1(B), in the present embodiment, a deformed steel shell 16 that locally bulges outward is generated obliquely below the tapping hole 14 .

Hereinafter, a method for repairing a shell of a converter furnace body according to one embodiment of the present invention will be described.
[STEP1]
All the refractories lining the inner surface of the furnace body 10 are removed to expose the steel shell 13. - 特許庁

[STEP2]
A three-dimensional measuring device (not shown) is installed in the furnace body 10 to measure the shape of the steel shell 13 as three-dimensional coordinate values. At that time, three or more (three in this embodiment) reference markers 25 are installed on the inner surface of the steel shell 13 (see FIGS. 5A and 5B), and the three-dimensional coordinate values of each reference marker 25 are Also measure
As the three-dimensional measuring device, a three-dimensional laser scanner or the like can be used, which can obtain the three-dimensional coordinates of the surface shape by radially irradiating the object to be measured with a laser.

[STEP3]
The difference between the three-dimensional coordinate value (actual shape measurement value) of the steel shell 13 measured by the three-dimensional measuring device and the three-dimensional CAD data (designed shape value) of the steel shell 13 is calculated as the deformation amount of the steel shell 13 .
In calculating the difference, it is necessary to align the coordinate axes of the three-dimensional coordinates of the measured shape values with those of the coordinate system of the shape design values. In this embodiment, the coordinate system of the shape design values is a cylindrical coordinate system, and the center of the approximate circle of the furnace throat 10d profile is the origin. The axis (furnace body center axis) passing through the origin and the approximate circle center of the profile at an arbitrary height position of the straight body portion 10b is the Z-axis, and the center of the tapping port 14 is placed on a plane perpendicular to the Z-axis and passing through the origin. Let the X-axis be the axis that passes through the projected point and the origin.

In the conversion of the shape measured value 17 to the coordinate system of the shape design value 18, as shown in FIGS. Above, the approximate circle center c of the flat cross section b that is closest to the circular profile of the shape design value 18 is taken from among the measured shape value profiles of the direct acting portion 10b, and the axis connecting a and c is defined as the Z axis. As with the coordinate system of the shape design value 18, the X-axis is an axis passing through the origin and a point obtained by projecting the center d of the tapping port 14 onto a plane perpendicular to the Z-axis and passing through the origin.

As described above, the difference between the three-dimensional coordinate values (measured shape values) coordinate-transformed in accordance with the coordinate system of the shape design values and the three-dimensional CAD data (shape design values) is defined as the amount of deformation of the steel shell 13 .
Incidentally, the three-dimensional coordinate values of each reference marker 25 measured in [STEP 2] are similarly coordinate-transformed according to the coordinate system of the shape design values.

[STEP4]
The deformation amount of the surrounding area including the deformed portion 16 of the skin to be repaired is represented by a contour map, and the contour line to be the cutting line is determined.
FIG. 3 is a contour map showing the amount of deformation of the peripheral region including the deformed portion 16 of the shell as viewed from inside the furnace body 10 . In the figure, a curve indicated by reference numeral 20 is a contour line with a deformation amount of 75 mm in the out-of-furnace direction, and is a cutting line in the present embodiment. On the other hand, the straight line indicated by reference numeral 22 is a rectangular cutting line according to the method described in Patent Document 1, and the straight line indicated by reference numeral 21 is a cut when the rectangular repair range is further reduced in the method described in Patent Document 1. is a line.

FIG. 4 shows a graph schematically showing the alignment between the cut surfaces 20a, 21a, 22a and the new steel shells 20b, 21b, 22b along the cutting lines 20, 21, 22. As shown in FIG.
At the position of the cutting line 20, the contour line and the cutting line match, so the deformation amount of the cut surface 20a is constant, and the new steel shell 20b and the surface match. Since the cutting line crosses the contour line, the amount of deformation of the cut surfaces 21a and 22a differs depending on the position, and it can be seen from the same figure that the new steel shells 21b and 22b do not match with each other. In particular, in the case of the cutting line 21 in which the rectangular repair range is reduced, it can be seen from the same figure that the contact between the cut surface and the new steel shell deteriorates.

In determining the cutting line, it is desirable not only to minimize the repair range, but also to avoid interference with other skeleton structures (in this embodiment, the tapping port 14 and the ribs 15).

[STEP5]
The three-dimensional coordinate values of the contour line that becomes the cutting line 20 are input to the projector.
For example, a laser marker or the like can be used as the projector.
Note that the three-dimensional coordinate values to be input are three-dimensional coordinate values in the coordinate system of the shape design values adjusted in [STEP 3], and are three-dimensional coordinate values with the projector as the center of the coordinate system.

[STEP6]
A projector 24 is installed in the furnace body 10 (see FIGS. 5A and 5B), and a cutting line 20 is projected onto the inner surface of the steel shell 13 to mark the cutting line 20 (see FIG. 6). At the same time, based on the three-dimensional coordinate values of the cutting line 20, the new steel shell and the backing plate are processed off-line.
When the projector 24 is installed in the furnace body 10 to irradiate the inner surface of the steel shell 13 with the cutting line 20, first, the distance between the projector 24 and each reference marker 25 is measured using a laser rangefinder or the like. Then, in [STEP 3], the position (three-dimensional coordinate value) of the projector 24 is determined based on the three-dimensional coordinate value of each reference marker 25 coordinate-transformed into the coordinate system of the shape design value. Based on the deviation between the three-dimensional coordinate value of the projector 24 and the center of the coordinate system, the three-dimensional coordinate value of the contour line that becomes the cutting line 20 input to the projector 24 is corrected. to irradiate. The marking of the cutting lines 20 is performed by an operator marking the cutting lines 20 irradiated on the inner surface of the steel shell 13 .

[STEP7]
The steel shell 13 is cut along the marking lines 26 (see FIG. 6) drawn on the inner surface of the steel shell 13, and a new steel shell is welded to the cut portion.
The steel shell 13 is cut by a three-dimensional automatic gas cutting machine or manually.
In addition, when welding a new steel shell to the cut point, follow the procedure below.
After performing welding groove processing on the cut surface, attach the backing plate. The shape of the groove is determined in consideration of the penetration during welding and the amount of welding, but generally a groove angle of about 30° is secured. In order to prevent defects and post-cracks in the welded part, preheating and post-heating management and maintenance of the welded part are performed during construction.

[STEP8]
After welding is completed, non-destructive inspections such as ultrasonic inspection and magnetic particle flaw detection are performed on the welded portion to confirm the soundness of the welded portion.

Although one embodiment of the present invention has been described above, the present invention is not limited to the configuration described in the above-described embodiment. Other possible embodiments and modifications are also included.

10: furnace body (converter furnace body), 10a: furnace bottom part, 10b: straight body part, 10c: narrowed part, 10d: furnace mouth, 11: trunnion ring, 12: trunnion, 13: steel shell (converter furnace body shell), 14: tapping port, 15: rib, 16: deformed part of the shell, 17: measured shape value, 18: shape design value, 17a, 18a: diameter, 20, 21, 22: cutting line, 20a, 21a, 22a: cut surface, 20b, 21b, 22b: new steel skin, 24: projector, 25: reference marker, 26: marking line

Claims (1)

A method for repairing a locally deformed steel shell of a converter furnace, comprising:
A step of removing the refractory lining on the inner surface of the converter furnace body to expose the steel shell of the converter furnace body;
A step of installing a three-dimensional measuring device in the converter furnace body to measure the shape of the converter furnace body shell;
a step of calculating the difference between the shape measured value and the shape design value of the converter furnace body shell to determine the deformation amount of the converter furnace body shell;
The amount of deformation in the peripheral area including the deformed portion of the steel shell of the converter furnace body to be repaired is represented by a contour map, the contour line to be the cutting line is determined, and the three-dimensional coordinate values of the contour line to be the cutting line are input to the projector. and
A step of setting the projector in the converter furnace body, irradiating the cutting line on the inner surface of the converter furnace body shell to mark the cutting line;
A method for repairing a converter furnace body shell, comprising: cutting the converter furnace body shell along a scribe line, and welding a new shell to the cut portion.

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