JP6790873B2 - Hot scarfer - Google Patents

Description

The present invention relates to a hot scarfer.

As described in Patent Document 1, it is known to melt the surface of a slab or the like using a hot scarfer. When the welding is performed non-uniformly, so-called tiger cutting occurs in which irregularities extending in the melting direction of the hot scarfer occur as shown in FIG. Performing uniform melting in the slab width direction with a hot scarf reduces the process of processing tiger mowing with a hand scarf and reduces the heating furnace basic unit by improving the hot slab heating furnace charging (Hot Charge and Rolling) rate. It is important to bring about. A hot scarfer is configured by arranging a plurality of smelting units with upper and lower blocks attached to the base block side by side. In order to ensure uniform shaving performance in the width direction, the smelting unit It has been conventionally found that it is important to make the gap (hereinafter referred to as the slot gap) that is the path of oxygen formed between the upper block and the lower block constant.

JP-A-2010-201498

However, when assembling the latheing unit, even if the laminating unit with the upper block and the lower block fixed to the base block with screws is attached to the actual machine while adjusting so that the slot gap is constant, the width will be wide when the operation is started. The slot gap is arbitrarily reduced for each of a plurality of welding units mounted in the direction. Therefore, when the operation was started, the slot gap became uneven in the width direction. For this reason, there has been a demand for a welding unit in which the slot gap does not change even when the operation is started and the above-mentioned tiger cutting does not occur. As a result of diligent studies on the cause of the decrease in the slot interval, the present inventor was able to elucidate the cause of the decrease in the slot interval.

The present invention has been made in this way, and an object of the present invention is to provide a hot scarfer that suppresses uneven melting due to a change in the slot gap formed by the upper block and the lower block. Is to provide.

The present invention made to solve the above problems employs the following means. First, the first means is an upper block, a lower block that forms a slot gap that becomes an oxygen gas path for milling when combined with the upper block, and a shoe that is arranged closer to the object to be processed than the lower block. It is a hot scarfer equipped with a plurality of welding units, and has a gap of 0.20 mm or more between the lower block and the shoe in the range from the widthwise edge of the welding unit to the inside by 30 mm. It is a hot scarfer characterized by being used.

Further, in the first means, in order to form the gap of 0.20 mm or more, the shim is sandwiched between the shoe of the hot scarfer and the lower block in the width direction center side by 30 mm or more from the width direction edge. Is preferable.

Further, in the first means, in order to form the gap of 0.20 mm or more, it is preferable that the upper surface of the shoe facing the lower block is cut out.

Further, in the first means, in order to form the gap of 0.20 mm or more, it is preferable that the lower surface of the lower block facing the shoe is cut out.

Further, in the first means, in order to form the gap of 0.20 mm or more, a build-up portion is provided at a position on the center side in the width direction of 30 mm or more from the width direction edge of the upper surface of the shoe. preferable.

Further, in the first means, in order to form the gap of 0.20 mm or more, a build-up portion is provided at a position on the center side in the width direction of 30 mm or more from the width direction edge of the lower surface of the lower block. Is preferable.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a hot scarfer that suppresses non-uniformity of welding due to a change in the slot gap formed by the upper block and the lower block.

It is a schematic perspective view about a part of a hot scarfer. It is a figure which shows the relationship between the object to be processed at the time of slab, and the smelting unit located above it. It is a perspective view which looked at the welding unit from the diagonally lower side. It is the figure which exaggerated the deformed state in the conventional welding unit. It is a partially enlarged view of the side surface of a welding unit. It is a figure which showed the value of the slot gap at the time of mounting and the slot gap after use for 24 hours in a conventional welding unit. It is a figure which showed the outline of the structure of the welding unit in Example 1. FIG. It is a figure which showed the value of the slot gap at the time of mounting and the slot gap after use for 24 hours in the welding unit of Example 1. It is a figure which showed the outline of the structure of the welding unit in Example 2. FIG. It is a figure which showed the value of the slot gap at the time of mounting and the slot gap after using for 24 hours in the welding unit of Example 2. It is a figure which showed the outline of the structure of the welding unit in Example 3. FIG. It is a figure which showed the value of the slot gap at the time of mounting and the slot gap after using for 24 hours in the welding unit of Example 3. It is a figure which showed the outline of the structure of the welding unit in Example 4. FIG. It is a figure which showed the value of the slot gap at the time of mounting and the slot gap after using for 24 hours in the welding unit of Example 4. It is a figure which showed the outline of the structure of the welding unit in Example 5. It is a figure which showed the value of the slot gap at the time of mounting and the slot gap after using for 24 hours in the welding unit of Example 5. It is a graph which showed the ratio of the number of tiger mowing occurrence slabs. It is a figure which showed the trouble which occurs when the uniform welding could not be performed.

Hereinafter, embodiments of the invention will be described. First, the schematic configuration of the hot scarfer 1 will be described, and then the analysis content regarding the occurrence of the reduction of the slot gap 26 that occurs during operation will be described. The hot scarfer 1 includes a plurality of welding units 2. As can be understood from FIGS. 1 to 3, the welding unit 2 is formed by attaching the upper block 22, the lower block 23, and the shoe 24 to the base block 21. When assembling the hot scarfer 1, the upper block 22 and the lower block 23 are fixed to the base block 21 with the lock pin 29. The lock pin 29 is fixed by tightening it with a nut through predetermined holes in the upper block 22 and the lower block 23. At that time, the positions of the two parts are adjusted and fixed so that the slot gap 26 is constant. doing. However, even if the slot gap 26 of each smelting unit 2 is adjusted to be the same when it is cold before the operation, the slot gap 26 is reduced when the smelting unit 2 is attached to the actual machine and the operation is started. Moreover, since the amount of reduction of the slot gap 26 is slightly different in each welding unit 2, it is considered to be so-called tiger hunting. Thermal stress analysis was performed to clarify the cause.

The mechanism of failure occurrence found by the thermal stress analysis will be described together with the explanation of the usage mode of the hot scarfer 1. FIG. 2 is a view of the welding unit 2 viewed from the width direction of the slab, which is the object 10 to be processed. Further, although not shown, the hot scarfer 1 arranges the welding unit 2 at symmetrical positions with the object to be processed 10 interposed therebetween. Therefore, in reality, the melting unit 2 as shown in FIG. 2 is arranged so as to be upside down under the slab which is the object to be processed 10, and both the upper surface and the lower surface of the object 10 to be processed are melted at the same time. It has a structure that can be scraped. The mechanism of failure occurrence is the same for the smelting unit 2 arranged above and below the object 10 to be processed. Therefore, in the following, the smelting unit 2 arranged above the object 10 to be processed will be used as an example. And explain.

As shown in FIG. 2, when the unprocessed object 10 such as a slab is melted, the melting unit 2 is brought into contact with the object 10 to be melted. During high-temperature slab melting (the slab temperature at the time of analysis is 800 ° C.), the slab contact surface side of the shoe 24 attached under the lower block 23 becomes hot, and as shown in FIG. 4, the shoe 24 expands thermally. The whole is transformed into a mortar shape that is convex downward. At this time, the lower block 23 is pushed upward by both sides of the shoe 24 that shifts upward. Note that FIG. 4 is a view of the hot scarfer 1 viewed from the upstream in the slab moving direction, and shows only 1/2 of the slab unit 2 in the width direction. Further, for easy understanding, FIG. 4 is exaggeratedly shown assuming that the deformation is 100 times the actual amount of deformation only in the vertical direction.

The lower block 23 is tightened to the lock pin 29 of the base block 21 with a nut, and a static friction force is generated on the contact surface between the lower block 23 and the base block 21 due to the axial force generated by the tightening torque of the nut. Thermal stress analysis revealed that the lower block 23 moves upward and the slot gap 26 shrinks because the pushing force of the lower block 23 generated by the thermal deformation of the shoe 24 is larger than the static friction force generated by tightening the nut. ..

From this, it was found that preventing the heat-deformed shoe 24 from pushing up the lower block 23 is effective in suppressing the change in the slot gap 26. More specifically, when the upper block 22, the lower block 23, and the shoe 24 are attached to the base block 21 and the slot gap 26 is adjusted to a constant value and attached, the shoe 24 is placed between the shoe 24 and the lower block 23. It has been found that providing a void larger than the amount of thermal deformation is effective as a means for suppressing the shrinkage of the slot gap 26.

Thermal stress analysis revealed that both sides of the shoe 24 had an upward shift of 0.18 mm. From this, it was found that providing a gap S of 0.18 mm or more between the shoe 24 and the lower block 23 is effective in suppressing the change in the slot gap 26. Practically, it is preferable to provide a gap S of 0.20 mm or more between the shoe 24 and the lower block 23. However, if the gap S between the shoe 24 and the lower block 23 becomes too large, the scale during melting may accumulate in the gap S, so that the gap S between the shoe 24 and the lower block 23 is too large. It is better not to have it. For example, as shown in FIG. 5, if a 1 mm gap S is provided in advance between the shoe 24 and the lower block 23 and the shoe 24 and the lower block 23 are attached to the base block 21, the lower block 23 is lifted by the deformation of the shoe 24. It is possible to suppress the occurrence of such a situation. Therefore, the lower block 23 does not move upward during operation, the slot gap 26 can be prevented from shrinking, and tiger cutting can be prevented.

Further, when the results of the thermal stress analysis were confirmed, it was found that the range in which the shoe 24 pushes the lower block 23 upward is approximately 30 mm from the edge. From this, the present inventor has found that the range in which the gap S between the shoe 24 and the lower block 23 is required is only 30 mm from the edge.

Here, the configuration of the hot scarfer 1 of the present embodiment will be described. As shown in FIGS. 1 to 3 and 5, the hot scarfer 1 includes an upper block 22 and a lower block 23 that, when combined with the upper block 22, forms a slot space that serves as an oxygen gas path for milling. The welding unit 2 is provided. Further, a shoe 24 arranged on the object 10 side of the lower block 23 is also provided. The hot scarfer 1 of the present embodiment has a range from the widthwise edge of the welding unit 2 to the inside by 30 mm so that the deformation of the shoe 24 caused by the heat during operation does not adversely affect the lower block 23. Is provided with a gap S of 0.20 mm or more between the lower block 23 and the shoe 24. Therefore, the slot gap 26 formed by the upper block 22 and the lower block 23 does not change from the time of the preliminary adjustment even when the operation is started, and the so-called tiger hunting can be suppressed as a hot scarfer 1. it can.

In order to provide a gap S in a range of 30 mm from the width direction edge of the welding unit 2, for example, a shim, which is a spacer for height adjustment, is sandwiched between the shoe 24 and the width direction center portion of the lower block 23. Can be considered. By doing so, it is possible to surely create the necessary gap S at the edge portion. The same effect can be obtained by cutting out the edge portion of the shoe 24 or the lower block 23 without sandwiching the shim. Further, the same effect can be obtained by attaching a build-up portion instead of a shim to the widthwise center portion of the shoe 24 or the widthwise center portion of the lower block 23.

In the hot scarfer 1 of the present embodiment, a plurality of welding units 2 are arranged side by side in the width direction. Therefore, it is possible to secure the size of the hot scarfer 1 while suppressing the increase in size of the welding unit 2. However, the so-called tiger mowing may be affected by the difference in slot spacing between the shaving units 2 arranged in the width direction of the hot scarfer 1, and in order to prevent the occurrence, the slot gap 26 is kept constant between the shaving units 2. There is a need to. Regarding this, when assembling the welding unit 2, the lock pin 29 fixed to the base block 21 is passed through a hole 1 mm larger than the diameter of the lock pin 29 drilled in the upper block 22 and the lower block 23, and the slot is inserted. The positions of the upper block 22 and the lower block 23 may be adjusted and tightened with bolts so that the gap 26 becomes constant.

Furthermore, after mounting the welding unit 2 on the actual machine that serves as the mounting base, loosen the bolts that fasten the upper block 22 and the lower block 23 to the base block 21 to keep the slot gap 26 of the adjacent welding units 2 constant. After that, the slot gap 26 can be made constant between the welding units 2 by tightening the bolts and making fine adjustments. Even if the melting unit 2 is thermally deformed during the operation, the lower block 23 does not move due to the above-mentioned measures, so that the operation can be continued while the slot gap 26 remains constant.

Next, the measurement results of the slot gap 26 immediately after the welding unit 2 is attached and after the operation for about 24 hours will be described. The width of each of the smelting units 2 is about 270 mm, and six smelting units 2 are mounted side by side in the width direction in the actual machine, and the upper surface of the object 10 to be processed can be smelted. It has such a structure. Since the slot gap 26 is measured at three points on both sides and the center portion for one melting unit 2, the number of measurement points in the width direction is 18. FIG. 6 shows the measurement results of the slot gap 26 immediately after the welding unit 2 belonging to the prior art is attached and after the operation for about 24 hours. At the time of installation, the bolts that fasten the upper block 22 and the lower block 23 to the base block 21 are loosened and adjusted so that the slot gap 26 becomes constant. Therefore, the variation in the width direction of the slot gap 26 immediately after installation is shown in the figure. Even in the example shown in 6, it is very small.

However, when the welding unit 2 belonging to the prior art is used, it can be seen that the slot gap 26 is reduced by 1 mm or more depending on the position in the width direction about 24 hours after the start of operation. This is because the shoe 24 is thermally deformed during operation and the widthwise edge portion of the shoe 24 pushes the lower block 23, so that the slot gap 26 is reduced.

The reduction of the slot gap 26 due to such a situation is in the range from the widthwise edge of the welding unit 2 to the inside by 30 mm, and the gap S of 0.20 mm or more is between the lower block 23 and the shoe 24. This can be dealt with by providing the above, but the specific means will be described below.

First, as a countermeasure against the reduction of the slot gap 26, a case where the shim 11 is sandwiched between the shoe 24 and the lower block 23 at the center position in the width direction will be described. For example, as shown in FIG. 7, a gap S of 0.20 mm or more is formed by sandwiching the shim 11 30 mm or more from the widthwise edge of the shoe 24 of the hot scarfer 1 and the lower block 23 to the center side in the width direction. The shim 11 of this embodiment is made of stainless steel having a size of 20 mm × 20 mm and a thickness of 0.5 mm. FIG. 8 shows the measurement results of the slot gap 26 immediately after the shim 11 is attached and after the shim 11 is operated for 24 hours. It was confirmed that the slot gap 26 hardly changed even before and after the operation for 24 hours, and the variation in the width direction was stable in a very small state.

Next, as a countermeasure for reducing the slot gap 26, a case where the upper surface of the shoe 24 facing the lower block 23 is cut out will be described. For example, as shown in FIG. 9, the upper surface of the shoe 24 in contact with the lower block 23 from the width direction edge to 30 mm is cut out by 0.5 mm to provide the notch 12. Since the same measurement as in Experiment 1 was performed on the hot scarfer 1 provided with the gap S of 0.20 mm or more in this way, the result is shown in FIG. It was confirmed that the slot gap 26 hardly changed before and after the operation for 24 hours, and the variation in the width direction was stable in a very small state.

Next, as a countermeasure against the reduction of the slot gap 26, a case where the lower surface of the lower block 23 facing the shoe 24 is cut out will be described. For example, as shown in FIG. 11, the lower surface of the lower block 23 in contact with the shoe 24 from the width direction edge to 30 mm is cut out by 0.5 mm to provide the notch 13. Since the same measurement as in Example 1 was performed on the hot scarfer 1 provided with the gap S of 0.20 mm or more in this way, the result is shown in FIG. It was confirmed that the slot gap 26 hardly changed before and after the operation for 24 hours, and the variation in the width direction was stable in a very small state.

Next, as a countermeasure against the reduction of the slot gap 26, a case where a build-up portion is provided at a position on the center side in the width direction of 30 mm or more from the edge in the width direction of the upper surface of the shoe 24 will be described. For example, as shown in FIG. 13, a build-up portion 14 having a width direction of 50 mm and a height of 0.5 mm is provided on the upper surface of the shoe 24. Since the same measurement as in Example 1 was performed on the hot scarfer 1 provided with the gap S of 0.20 mm or more in this way, the result is shown in FIG. It was confirmed that the slot gap 26 hardly changed before and after the operation for 24 hours, and the variation in the width direction was stable in a very small state.

Next, as a countermeasure for reducing the slot gap 26, a case where a build-up portion is provided at a position on the center side in the width direction of 30 mm or more from the width direction edge of the lower surface of the lower block 23 will be described. For example, as shown in FIG. 15, a build-up portion 15 having a width direction of 50 mm and a height of 0.5 mm is provided on the lower surface of the lower block 23. Since the same measurement as in Example 1 was performed on the hot scarfer 1 provided with the gap S of 0.20 mm or more in this way, the result is shown in FIG. It was confirmed that the slot gap 26 hardly changed before and after the operation for 24 hours, and the variation in the width direction was stable in a very small state.

FIG. 17 shows the ratio of the number of tiger cutting occurrence slabs before the countermeasure for the reduction of the slot gap 26 and when the countermeasures of Examples 1 to 5 are implemented. From FIG. 17, it can be seen that the ratio of the number of slabs in which tiger cutting occurs was significantly reduced in all the measures of Examples 1 to 5 as compared with those before the measures.

As described above, in the range from the widthwise edge of the welding unit 2 to the inside by 30 mm, the above-mentioned upper block 22 and the lower portion are provided so as to provide a gap S of 0.20 mm or more between the lower block 23 and the shoe 24. By adjusting the position of the block 23, it is possible to prevent the lower block 23 from moving even if the shoe 24 is thermally deformed during the operation, and it is possible to continue the long-term operation with the slot gap 26 constant as in the embodiment. Therefore, the ratio of the number of slabs generated during shaving can be significantly reduced. Therefore, it is possible to reduce the cost by preventing the increase in the number of processes of the hand scarf and reduce the heating furnace unit by improving the HCR rate.

The present invention is not limited to the above embodiments, and it goes without saying that the present invention can be applied without departing from the spirit of the present invention. For example, the shim, the build-up portion, and the like are not limited to being provided at only one place for one welding unit, but can be provided at a plurality of places.

It is also possible to have a configuration in which a plurality of upper units and lower units are provided in one base block.

The means for providing the gap may be configured by combining a plurality of means. For example, by combining the build-up portion and the shim so that the upper unit and the lower unit are connected at a plurality of places, a desired gap can be provided between the lower block and the shoe.

1 Hot scarfer 2 Melting unit 10 Material to be processed 11 Sim 12 Notch 13 Notch 14 Overlay 15 Overlay 21 Base block 22 Upper block 23 Lower block 24 Shoe 26 Slot gap

Claims (1)

A smelting unit including an upper block, a lower block that constitutes a slot gap that becomes an oxygen gas path for smelting when combined with the upper block, and a shoe that is arranged on the object side of the lower block. A hot scarfer with multiple
at least,
Inserting the shim from the widthwise edge of the hot scarfer shoe and the lower block to the center side in the width direction by 30 mm or more,
Notch on the top of the shoe facing the lower block,
Notch on the underside of the lower block facing the shoe,
Addition of overlay to the position on the center side in the width direction of 30 mm or more from the width direction edge of the upper surface of the shoe,
Addition of overlay to the position on the center side in the width direction of 30 mm or more from the width direction edge of the lower surface of the lower block
1 or more of
A hot scarfer that ranges from the widthwise edge of the welding unit to the inside by 30 mm and is characterized by a gap of 0.20 mm or more between the lower block and the shoe.