JP4218461B2 - Welding equipment - Google Patents

Description

  The present invention relates to a welding apparatus that uses an oxygen gas or the like to perform the surface cutting of a slab, a steel slab, or the like.

  In the manufacturing process of steel products, slabs cast by a continuous casting machine and steel slabs that are disintegrated and rolled from steel ingots cast by the ingot-making method are hot rolled into a predetermined shape to become steel products. If there are cracks on the surface of the slab and steel slab (hereinafter referred to as “cast steel slab”) or if there are non-metallic inclusions such as mold powder in the vicinity of the surface, after rolling or after surface treatment such as plating It appears on the surface of steel products as wrinkles and is the main cause of product yield loss. Therefore, in the case of a cast steel slab of a steel type in which defects such as cracks are likely to occur on the surface, it is generally performed that the next layer is subjected to hot rolling after the surface layer of the cast steel slab is, for example, about 2 mm. Yes.

  In order to care for the surface of the cast steel piece, a so-called hot scarfer or a cold scarfer as shown in Patent Document 1, for example, is used. This welding machine is provided with a torch unit in which a slit-like oxygen gas ejection hole for cutting is formed between an upper block and a lower block, and the upper block and the lower block are integrally formed. 2. Description of the Related Art In a cutting apparatus for cutting a wide cast steel piece such as a cast piece, a number of torch units are arranged side by side along the width direction of the cast steel piece. Usually, the upper block and the lower block are provided with a flammable gas injection hole, and a heating flame is formed by the oxygen gas and the flammable gas injected from the oxygen gas injection hole for cutting, and cast steel pieces. It is designed to heat and heat. In this case, in order to promote preheating of the cast steel piece, the upper block may be provided with a preheating oxygen gas ejection hole.

However, when the cutting is performed using the welding apparatus having such a configuration, a valley (unevenness) may occur on the surface of the cast steel piece after the cutting, and when the difference between the valleys is significant, hot rolling is performed. Occasionally, the ridges (convex parts) collapse, and scaled surface defects may occur in the product after rolling.
JP-A-9-210320

  In spite of the need for a welding machine that can provide a smooth cut surface without generating valleys and valleys on the surface of the cast steel piece after cutting, there has been no effective means in the past. If a valley that causes a scale-like surface defect occurs on the surface, it is unavoidable to grind and remove the peak using a grinder, etc., not only reducing the surface maintenance efficiency of the cast steel piece, but also manufacturing. The cost was increasing.

  The present invention has been made in view of the above circumstances. The purpose of the present invention is that when a cast steel slab is subjected to scouring, no hills or valleys are generated on the surface of the cast steel slab after slicing. Therefore, the present invention is to provide a cutting apparatus capable of obtaining a cut surface that does not cause a scale defect in a hot rolling process even if the difference between the two is small and the surface care is not performed again.

  The present inventors have intensively studied to solve the above problems. As a result, it was found that the difference between the peaks and valleys of the cut surface was significant at the joint portion of the torch units arranged in the width direction of the cast steel pieces. The slit-shaped oxygen gas injection hole for cutting formed in the torch unit is formed by a pair of end walls installed between the upper block and the lower block at both ends, the upper surface is formed by the upper block, and the lower surface is formed by the lower block. Is formed by. Therefore, in the joint part of the torch unit, since the end wall exists, the flow of oxygen gas ejected from the oxygen gas ejection hole for cutting is disturbed, and due to the disorder of the flow of oxygen gas, It seemed that the difference between the mountains and valleys became significant at the joint between adjacent torch units.

  Accordingly, the cutting test was carried out by changing the shape of the peas in various ways. As a result, it was found that by arranging an appropriately shaped end wall, the difference between the peaks and valleys was suppressed, and the surface of the cast steel piece after the thermal cutting was smoothed.

  The present invention has been made on the basis of the above knowledge, and the welding apparatus according to the first invention has a pair of end walls arranged between the upper block and the lower block as both ends, and the upper surface as the upper block. And a lower surface of the lower part of the oxygen gas jetting hole having a slit-like shape, and the width of the oxygen gas jetting hole for cutting is equal to that of the oxygen gas jetting hole for cutting. The end wall has a shape in which the width of the part in the longitudinal direction is the largest so as to become narrow in the middle of the flow direction.

  According to a second aspect of the present invention, in the first aspect, the wall surface shape of the end wall forming the oxygen gas ejection hole for cutting is streamlined.

  According to a third aspect of the present invention, in the first or second invention, the end wall has a difference of 5 mm or more between the maximum width and the minimum width in the longitudinal direction of either end wall. It is 30 mm or less.

  According to the present invention, since the width of the oxygen gas ejection hole for cutting is narrowed in the middle of the flow direction of the oxygen gas ejection hole for cutting, the oxygen gas ejected from the oxygen gas ejection hole for welding The flow in the width direction becomes uniform, a uniform heating flame can be formed in the width direction, and the surface of the cast steel piece can be evenly cut at the joint portion of the torch unit. As a result, the difference between the peaks and valleys on the surface of the cast steel slab after cutting is reduced, and even if surface cleaning is not performed again, the scale defect in the hot rolling of the next process is greatly reduced, resulting in low cost and high cost. Manufacturing quality steel products is achieved and has industrially beneficial effects.

  Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. 1 and 2 are diagrams showing an embodiment of the present invention, in which FIG. 1 is a schematic diagram showing an example of a torch unit portion of a cutting apparatus according to the present invention, and FIG. 2 is shown in FIG. It is the schematic which shows the positional relationship of a lower block and an end wall.

  As shown in FIGS. 1 and 2, the torch unit 2 includes a head block 3, an upper block 4, a lower block 5, a shoe block 6, and a pair of end walls 7. It is installed at the bottom. The manifold 8 is installed in the width direction of the cast steel piece 9 to be subjected to the cutting, and holds a plurality of torch units 2 arranged in the width direction of the cast steel piece 9, that is, in the lateral direction, and at the same time, each torch unit. 2 for distributing oxygen gas, combustible gas, cooling water, etc.

  A pair of end walls 7 are installed in a state of being sandwiched between the upper block 4 and the lower block 5, and are used for injecting oxygen gas for cutting between the upper block 4 and the lower block 5. A working oxygen gas ejection hole 10 is formed. That is, a slit-shaped space that is surrounded by the pair of end walls 7, the upper block 4, and the lower block 5 and that extends in the lateral direction functions as the oxygen gas ejection hole 10 for cutting. The end wall 7 is for preventing the upper block 4 and the lower block 5 from being deformed by thermal stress during the cutting and closing the oxygen gas injection hole 10 for the cutting and preventing the oxygen gas from being discharged. Yes, as shown in FIG. 2, they are installed at both ends of the upper block 4 and the lower block 5. The oxygen gas ejection hole 10 for cutting is communicated with an oxygen gas passage 11 that passes through the head block 3 and reaches the manifold 8, and the oxygen gas passage 11 is connected to an oxygen gas supply pipe for cutting installed in the manifold 8. Communicate. That is, oxygen gas supplied from the manifold 8 via the oxygen gas passage 11 is ejected from the oxygen gas ejection hole 10 for cutting. In FIG. 2, the white arrow indicates the direction in which the oxygen gas ejected from the cutting oxygen gas ejection hole 10 flows, and the symbol W represents the width of the oxygen gas ejection hole 10 for cutting.

  The upper block 4 communicated with a plurality of flammable gas injection holes 12 arranged in the lateral direction communicated with the combustible gas passage 13 via the tank 14 and the oxygen gas passage 16 for preheating via the tank 17. A plurality of preheating oxygen gas ejection holes 15 arranged in the lateral direction and a plurality of lateral combustion gas ejection holes 18 communicated with the combustible gas passage 19 via the tank 20 are provided, The lower block 5 is provided with a plurality of combustible gas ejection holes 21 arranged in the horizontal direction and communicated with the combustible gas passage 22 via a tank 23. The flammable gas passage 13, the preheating oxygen gas passage 16, the flammable gas passage 19, and the flammable gas passage 22 pass through the head block 3 to the manifold 8, and the preheating oxygen gas supply pipe installed in the manifold 8. And a combustible gas supply pipe. That is, the combustible gas supplied from the manifold 8 is ejected from the combustible gas ejection hole 12, the combustible gas ejection hole 18, and the combustible gas ejection hole 21, and the preheating oxygen gas supplied from the manifold 8 is preheated. The oxygen gas is ejected from the oxygen gas ejection hole 15.

  In the present invention, as shown in FIG. 2, the width (W) of the oxygen gas ejection hole 10 for cutting is determined by the direction in which oxygen gas flows in the oxygen gas ejection hole 10 for cutting (open arrow in FIG. 2). It is necessary to make the shape of the end wall 7 into a shape in which the width becomes maximum at a position in the middle of the end wall 7 in the longitudinal direction. In this case, it is preferable that the portion having the maximum width is located upstream of the longitudinal length of the end wall 7 in the oxygen gas flow direction. By doing so, the flow of oxygen gas ejected from the oxygen gas ejection hole 10 for cutting is not disturbed, and is uniformly mixed with the combustible gas ejected from the combustible gas ejection hole 21 of the lower block 5. In addition, a uniform heating flame can be formed in the width direction of the cast steel piece 9, and it is possible to suppress the generation of peaks and valleys (unevenness) on the surface of the cast steel piece 9 after the cutting.

  In order to further prevent the flow of oxygen gas, it is preferable that the shape of the wall surface of the end wall 7 forming the oxygen gas ejection hole 10 for cutting is streamlined. Furthermore, in order not to further disturb the flow of oxygen gas, the shape of the end wall 7 is different from the maximum width and the minimum width in the longitudinal direction of both the pair of end walls 7 in the range of 5 mm to 30 mm. It is preferable to make this shape. Since the end wall 7 is installed on both sides of the oxygen gas ejection hole 10 for cutting, the end wall 7 of the pair of end walls 7 has a difference between the maximum width and the minimum width in the longitudinal direction of 5 mm. Since it is preferable to set it as 30 mm or less, the width (W) of the oxygen gas ejection hole 10 for cutting becomes narrow in the range of 10 mm or more and 60 mm or less in the middle. When the minimum width of the end wall 7 is zero, the maximum width may be 5 mm or more and 30 mm or less.

  In this way, the cutting apparatus 1 according to the present invention is configured. Hereinafter, a method for cutting the cast steel piece 9 using the above-described cutting apparatus 1 according to the present invention will be described.

  The torch unit 2 is aligned with the end surface of the cast steel piece 9 and the combustible gas is ejected from the combustible gas ejection holes 12, 18, and 21, and at the same time, oxygen is discharged from the oxygen gas ejection hole 10 for cutting and the oxygen gas ejection hole 15 for preheating. After gas is ejected and ignited, a heating flame is formed and the cast steel piece 9 is sufficiently heated, the pressure of the oxygen gas ejected from the oxygen gas ejection hole 10 for cutting is increased to start cutting. As the combustible gas, CO gas, natural gas, propane gas, or the like can be used.

  If molten soot (mainly iron oxide) is generated on the surface of the end surface of the cast steel piece 9 and the cutting is confirmed, the cast steel piece 9 is ejected from the torch unit 2 at a predetermined speed while the torch unit 2 is fixed. 1 is moved in the direction opposite to the gas (from the left side to the right side in FIG. 1), and the entire surface of the cast steel piece 9 is subjected to cutting. The amount of cutting is adjusted by changing the moving speed of the cast steel piece 9. At that time, high pressure water sprayed from a high pressure water spray nozzle (not shown) is used so that the soot generated by melting the cast steel piece 9 is deposited on the surface of the cast steel piece 9 so as not to inhibit the cutting. To remove the cast steel piece 9 in a direction perpendicular to the moving direction of the cast steel piece 9.

  In this way, the surface of the cast steel piece 9 is subjected to the thermal cutting care, so that even the joint portion of the torch unit 2 can be uniformly welded, and the generation of peaks and valleys on the surface of the cast steel piece 9 after the cutting is achieved. It becomes possible to suppress.

  The present invention is not limited to the above description, and various modifications can be made. For example, although there are two flammable gas ejection holes installed in the upper block 4, there may be one or three or more, and the shape of the torch unit 2 must also be the above shape It is not something to do. In short, the present invention can be applied as long as it is a cutting apparatus having an oxygen gas ejection hole for cutting formed by an upper block, a lower block, and a pair of end walls.

  Using the fusing device 1 shown in FIG. 3, a slab slab cast of an ultra-low carbon steel cast by a slab continuous casting machine was conducted. As shown in FIG. 3, the used cutting apparatus 1 is a cutting apparatus 1 in which 11 torch units 2 shown in FIG. 1 are arranged in the width direction of the upper and lower surfaces of the cast steel piece 9 and two pieces are arranged in the thickness direction. Yes, it is a facility that allows the upper surface and the lower surface of the cast steel piece 9 to be subjected to the thermal cutting and maintenance at the same time. The surface temperature of the slab before performing the thermal cutting maintenance is about 280 ° C., the size of the slab is 250 mm in thickness, 1650 mm in width, and 10 m in length. Table 1 shows the composition of the slab.

  In this shave maintenance test, five levels of tests (test Nos. 1 to 5) using five types of peas with different shapes were carried out, and the shape of the spheres affecting the difference (irregularities) of the valleys and valleys on the slab surface. The effect of was investigated. FIG. 4 shows the shapes of the five types of end walls used in the test. 4A shows the end wall used in the test No. 1, which is a conventionally used end wall having a right-angled triangular shape and the longest side among the three sides of the triangle. However, the wall surface of the oxygen gas ejection hole for cutting is formed. In other words, the width (W) of the oxygen gas ejection hole for cutting is gradually increased toward the downstream direction of the flow of oxygen gas.

  4 (B) to (E) are the end walls used in Test Nos. 2 to 5, and the end wall within the scope of the present invention has a width (W) of the oxygen gas ejection holes for cutting. It is designed to become narrower in the middle of the flow of oxygen gas. (B) used in Test No. 2, (D) used in Test No. 4, and (E) used in Test No. 5 are shapes. Are streamlined and have different maximum widths, in the order of (B), (D), (E), 4 mm, 10 mm, and 35 mm end walls, while FIG. 4 (C) used in test No. 3 ) Has a triangular shape, but two sides other than the longest side of the three sides of the triangle form the wall surface of the oxygen gas ejection hole for cutting, and the end wall has a maximum width of 10 mm. . Although the minimum widths in the end walls of FIGS. 4A to 4E are all zero, it is not necessary to set the minimum width to zero.

  First of all, the slab is preheated for about 20 seconds by a flammable gas (here, C gas) and oxygen gas ejected from the upper block, and this preheating generates molten soot on the surface of the slab. After confirming this, the pressure of oxygen gas ejected from the oxygen gas ejection hole for cutting was increased, and at the same time, the slab was moved at a moving speed of 18 m / min to simultaneously shave the four surfaces of the slab. . The amount of cutting at a moving speed of 18 m / min is about 2 mm.

  After the slab cutting, the slab was air-cooled and scanned in the width direction of the slab using a laser distance meter, and the difference (irregularity) of the peaks and valleys on the slab surface was measured for 10 slabs in each test. Based on the data measured by the laser distance meter, the distance of the center part of the torch unit 2 is defined as zero, and the other parts are defined as the relative roughness when the distance of the center part is defined as the surface roughness. The depth of the joint part of 2 was quantified and evaluated.

Thereafter, the slab whose difference between the valleys and valleys was measured with a laser distance meter was placed in a heating furnace heated to 1200 ° C., taken out after heating for 120 minutes, and then subjected to 50 mm / pass width direction rolling once, After removing the scale with high-pressure water, rough rolling and finish rolling were performed to obtain a hot-rolled steel sheet having a thickness of 3.2 mm. Further, this hot-rolled steel sheet is cold-rolled to obtain a cold-rolled steel sheet having a thickness of 0.8 mm, and alloying with an adhesion amount of 50 g / m ² is performed on the front and back surfaces of the cold-rolled steel sheet using a continuous hot-dip galvanizing facility. Hot dip galvanizing was applied. Thereafter, the number of surface defects having a size of 1 mm or more generated per product coil of the galvannealed steel sheet was visually examined.

  Table 2 summarizes the maximum values of the ridge and valley differences investigated in the slab and the surface defect judgment results investigated in the galvannealed steel sheet. In the column for determining surface defects in Table 2, ◎ indicates that no surface defects exist, ○ indicates that the number of surface defects is 1 to 5 per coil, and Δ indicates that the number of surface defects is a coil. The number of surface defects is 6 to 20 per coil, and the cross indicates that the number of surface defects exceeds 20 per coil.

  As is apparent from Table 2, by performing surface scouring of the slab using the slab according to the present invention, the difference between the peaks and valleys of the slab surface is reduced, and when the conventional slab is used. In comparison, it was confirmed that the surface defects of the steel sheet were reduced. And it has confirmed that the effect was remarkable especially by making end wall into a streamline type and making the maximum width of end wall into the range of 5-30 mm.

It is the schematic which shows an example of the torch unit site | part of the welding apparatus which concerns on this invention. It is the schematic which shows the positional relationship of the lower block and end wall which are shown in FIG. 1 is a schematic view of a welding machine used in Example 1. FIG. It is the schematic which shows the shape of the end wall used in Example 1, (A) is the conventional end wall, (B)-(E) is the end wall which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Metal cutting apparatus 2 Torch unit 3 Head block 4 Upper block 5 Lower block 6 Shoe block 7 End wall 8 Manifold 9 Cast steel piece 10 Oxygen gas ejection hole 11 Oxygen gas passage 12 For burnable gas Combustion gas jet 13 DESCRIPTION OF SYMBOLS 14 Tank 15 Preheating oxygen gas ejection hole 16 Preheating oxygen gas passage 17 Tank 18 Flammable gas ejection hole 19 Flammable gas passage 20 Tank 21 Flammable gas ejection hole 22 Flammable gas passage 23 Tank

Claims (3)

  A cutting apparatus provided with a slit-like oxygen gas ejection hole for cutting, which is formed with a pair of end walls arranged between an upper block and a lower block as both ends, an upper surface as an upper block, and a lower surface as a lower block. The end wall has the largest width in the middle in the longitudinal direction so that the width of the oxygen gas ejection hole for cutting is narrowed in the middle of the flow direction of the oxygen gas ejection hole for cutting. A welding apparatus characterized by having a shaped shape.   2. The cutting apparatus according to claim 1, wherein a wall surface shape of the end wall forming the oxygen gas ejection hole for cutting is streamlined.   The end wall has a difference between a maximum width and a minimum width in the longitudinal direction of either end wall of a pair of 5 mm or more and 30 mm or less, according to claim 1 or 2. Welding equipment.

Images