JP7475059B2 - Upper preheat block extension and scarf unit and method of assembling same - Google Patents

Description

The present invention relates to an upper preheat block extension and scarf unit, as well as a method for assembling them.

Scarfing is a process in which the decarburized layer and surface defects of the workpiece (e.g., steel billet) are usually removed by a thermochemical oxidation reaction of oxygen gas and fuel gas (Patent Document 1). In steelworks, it is a surface treatment carried out before rolling steel billets. The equipment that carries out this type of scarfing is called a scarf machine (or scarfing machine), and is installed in steelworks all over the world.

The scarf device is primarily composed of a roller table on which the workpiece to be cut, such as a piece of steel, is placed and transported, and a scarf unit for cutting the workpiece transported by the roller table. A preheating flame (preheating flame) is applied from this scarf unit to the surface of the workpiece to be cut, preheating it and generating molten slag. The flame is then switched to the cutting flame (cutting flame), and a large amount of oxygen gas is sprayed onto the molten slag. At the same time, the workpiece is advanced toward the scarf unit using the roller table, and cutting is performed while generating molten slag through an oxidation reaction.

Japanese Patent Application Laid-Open No. 9-76060

The scarf unit is made up of a head block, upper block, lower block, and shoe block. Of these, the role of the upper block is to burn a mixture of oxygen gas and fuel gas to form a preheating flame, which is used to preheat the surface of the workpiece to be cut, and to form a pool of molten metal (the molten slag mentioned above) for cutting.

The structure of the oxygen gas hole (ejection passage) and fuel gas hole to form the preheat flame can be divided into tip type and insert nozzle type. The tip type has a longer history, but since the insert nozzle type was developed about 30 years ago, its adoption in steelworks and other facilities has been gradually increasing.
However, the insert nozzle type has more parts than the tip type, and assembly and disassembly take more time.

In particular, when assembling and maintaining the upper block, it is necessary to insert and fix an orifice plug to adjust the flow rate of oxygen gas inside the oxygen gas hole in the upper preheat block extension, which is part of the upper block. The fixing procedure involves applying a liquid gasket (liquid packing) to the top surface of the orifice plug, inserting it, and then waiting for the liquid gasket to dry before the orifice plug is fixed between the inner wall of the oxygen gas hole, which has resulted in longer work hours. This is because if the upper preheat block extension is moved before the liquid gasket dries, there is a risk that the orifice plug will become misaligned.

In addition, when disassembling and servicing the upper block, after removing the orifice plug from the upper preheat block extension, it is necessary to remove the dried liquid gasket that adheres to the inside of the upper preheat block extension and to the orifice plug, which makes the work take longer.

The present invention was made in consideration of the above problems, and aims to provide an upper preheat block extension and scarf unit for a scarf unit that allows easy attachment and detachment of an orifice plug, as well as an assembly method for the same.

In order to achieve the above object, the present invention provides an upper preheat block extension for a scarf unit that scarves an object to be scarified, comprising:
the upper preheat block extension has a shielding oxygen gas ejection passage for ejecting shielding oxygen gas and a central preheating oxygen gas ejection passage for ejecting preheating oxygen gas,
an orifice plug for adjusting a flow rate of the shielding oxygen gas is inserted into the inside of the shielding oxygen gas ejection passage and detachably fixed thereto;
The orifice plug is fixed via an elastic body for fixing the plug.

With such an upper preheat block extension of the present invention, the orifice plug can be firmly fixed inside the oxygen gas ejection flow passage for shielding by the elastic force of the plug fixing elastic body, and can also be easily removed. In this way, the orifice plug can be easily attached and detached, and the work time required for assembling and disassembling the upper preheat block extension can be significantly reduced compared to conventional products that use a liquid gasket.
Furthermore, in conventional products, the orifice hole in the orifice plug through which oxygen gas passes can be blocked by mistakenly applying a liquid gasket, causing poor preheating or poor machining. However, the present invention eliminates the concern of such orifice hole blockage.

The orifice plug has a recess on an upper surface facing an inner wall of the shielding oxygen gas ejection passage, the recess being shallower than a thickness of the plug fixing elastic body,
The orifice plug may be inserted and fixed in place with the plug fixing elastic body fitted in the recess.

With something like this, it is possible to fix the orifice plug using the plug fixing elastic body with a relatively simple mechanism.

The plug fixing elastic body can also be an O-ring.

O-rings themselves are commonly used parts and are easy to procure, making them ideal.

The plug fixing elastic body may be made of nitrile rubber.

Materials like these are preferable because they are inexpensive and highly wear-resistant.

The present invention also provides a scarf unit for melt-cutting an object to be melt-cut, the scarf unit comprising a head block, an upper block having a first fuel gas jet passage, a shielding oxygen gas jet passage and a central preheating oxygen gas jet passage, a lower block having a second fuel gas jet passage, and a shoe block in contact with the object to be melt-cut,
The upper block and the lower block are disposed on the front side of the head block so as to define a space between them to form an oxygen gas ejection slot for use in cutting, and the shoe block is disposed on the underside of the head block,
The present invention provides a scarf unit characterized in that the upper block has an upper preheat block base arranged on the head block and the above-mentioned upper preheat block extension of the present invention arranged on the upper preheat block base.

As described above, the ease of assembly and disassembly of the upper preheat block extension and the work time can be improved compared to conventional products, making the scarf unit as a whole easier to assemble and disassemble and reducing the required work time.
Furthermore, the scarf unit is free from poor preheating or poor welding caused by clogging of the orifice hole of the orifice plug by the liquid gasket.

The present invention also provides a method for assembling an upper preheat block extension for a scarf unit for scarfing an object to be scarfed, comprising the steps of:
The present invention provides a method for assembling an upper preheat block extension, characterized in that when an orifice plug for adjusting the flow rate of the shielding oxygen gas is inserted and removably fixed inside a shielding oxygen gas ejection passage in the upper preheat block extension for ejecting the shielding oxygen gas, the orifice plug is fixed via an elastic body for fixing the plug.

With this method of assembling the upper preheat block extension of the present invention, the orifice plug can be firmly fixed by the elastic force of the plug fixing elastic body. Assembly can be simplified, and the assembly work time can be significantly shortened compared to the conventional method. Moreover, when assembled using this method, the orifice plug can be easily removed when disassembling. In other words, not only the assembly but also the ease and work time of disassembly can be improved.
Also, the concern about the orifice hole of the orifice plug being blocked by the liquid gasket can be eliminated.

Also, when the orifice plug is fixed,
In the orifice plug, a recess is formed on an upper surface facing an inner wall of the shielding oxygen gas ejection passage, the recess being shallower than a thickness of the plug fixing elastic body;
With the plug fixing elastic body fitted in the recess, the orifice plug can be fixed by inserting it into the inside of the shielding oxygen gas ejection flow passage.

In this way, the orifice plug can be fixed by the plug fixing elastic body using a relatively simple mechanism.

The plug fixing elastic body can also be an O-ring.

In this way, an O-ring, which is easy to obtain, can be used as the elastic body for fixing the plug, which is convenient.

The plug fixing elastic body may be made of nitrile rubber.

Nitrile rubber is preferable because it is inexpensive and has excellent abrasion resistance.

The present invention also provides a method for assembling a scarf unit for melt-cutting an object to be melt-cut, the scarf unit comprising a head block, an upper block having a first fuel gas jet passage, a shielding oxygen gas jet passage and a central preheating oxygen gas jet passage, a lower block having a second fuel gas jet passage, and a shoe block that comes into contact with the object to be melt-cut, the method comprising:
The upper block and the lower block are disposed on the front side of the head block so as to define a space between them to form an oxygen gas ejection slot for surface cutting, and the shoe block is disposed on the underside of the head block.
The present invention provides a method for assembling a scarf unit, characterized in that the upper block is arranged using an upper preheat block base to be arranged on the head block and an upper preheat block extension assembled by the above-mentioned upper preheat block extension assembly method of the present invention.

As described above, the ease of assembly of the upper preheat block extension and the working time can be improved compared to the conventional method, so that the scarf unit as a whole can be easily assembled and the required working time can be shortened. Also, when assembled by this method, disassembly can be easily performed in a short time.
In addition, it is possible to assemble a scarf unit that is free from poor preheating or poor welding caused by clogging of the orifice hole of the orifice plug by the liquid gasket.

The upper preheat block extension and scarf unit of the present invention, as well as the assembly method thereof, make it easy to attach and detach the orifice plug, significantly shortening the work time required for assembly and disassembly, and eliminating the clogging of the orifice hole by the liquid gasket as in the past, as well as the resulting poor preheating and poor machining.

FIG. 2 is an explanatory diagram showing an example of a scarf unit of the present invention. FIG. 2 is an exploded view showing an example of the scarf unit of the present invention when disassembled. FIG. 2 is a perspective view of the upper preheat block extension of the present invention. FIG. 2 is a rear view of the upper preheat block extension of the present invention. FIG. 1 is a side view and an internal structure diagram showing an example of an orifice plug for use only on both ends. FIG. 2 is a side view and an internal structure diagram showing an example of an orifice plug for use exclusively on the inside. 10 is an explanatory view showing an example of a state in which a recess of the orifice plug and a plug fixing elastic body are fitted together. FIG. FIG. 13 is an explanatory diagram showing an example of an internal structure near an upper preheat block extension with an orifice plug inserted and fixed therein;

Hereinafter, the present invention will be described with reference to the drawings. However, the present invention is not limited to the embodiments.
First, the background to the invention will be briefly described.
Regarding the orifice plug to be disposed in the oxygen gas ejection passage for shielding of the upper preheat block extension, in the past, an orifice plug that matched the size of the oxygen gas ejection passage for shielding was simply inserted as it was.
However, as the orifice plug is repeatedly assembled, subjected to spalling treatment of steel pieces, and then disassembled and cleaned, the orifice plug wears down and becomes smaller in size, and when the orifice plug is inserted into the oxygen gas ejection passage for shielding, a gap appears between the orifice plug and the inner wall, causing it to lose stability. Therefore, in order to firmly fix the orifice plug, a liquid gasket (e.g., silicone-based) is now used instead of an adhesive to fix the orifice plug to the inner wall of the oxygen gas ejection passage for shielding.

Fixing with a liquid gasket was adopted because it does not undergo a chemical reaction when it comes into contact with oxygen gas, is resistant to heat environments, and has a proven track record of being used in the maintenance of scarf units. However, as mentioned above, assembly and disassembly takes time and effort, and applying the liquid gasket to the wrong place can cause problems such as clogging of the orifice hole.
As a result of intensive research by the present inventors, it was discovered that by using an elastic body to fix the orifice plug, assembly and disassembly can be easily performed without time or labor, and the problem of clogging of the orifice hole that occurs when a liquid gasket is used can be prevented, and the present invention was completed based on this discovery.

An example of the scarf unit of the present invention is shown in Figure 1. An exploded view of the scarf unit is shown in Figure 2. This scarf unit 1 is equipped with a mechanism for supplying oxygen gas and fuel gas to the workpiece (e.g., a steel piece) to remove decarburized layers and defects on the surface of the steel piece through a thermochemical reaction.
First, the scarf unit 1 of the present invention is roughly composed of a head block 2, an upper block 3, a lower block 4, and a shoe block 5.
The head block 2 may be made of brass, for example. The upper block 3, the lower block 4, and the shoe block 5 may be made of copper, for example. Copper is preferable because it has excellent thermal conductivity and can provide a high cooling effect. However, these materials are not particularly limited.

The head block 2 is structured with a manifold structure that includes a collection pipe for sending oxygen gas and fuel gas to the ejection passages and oxygen gas ejection slots for surface cutting of each block, which will be described later. In addition, water for cooling each block can also be sent.
An upper block 3 and a lower block 4 are disposed on the front side of the head block 2. These two blocks are disposed with a gap between them. The space between these two blocks constitutes an oxygen gas ejection slot 6 for ejecting oxygen gas for etching.

The upper block 3 also has an upper preheat block base (hereinafter also referred to as UPBB) 7 disposed on the head block 2, and an upper preheat block extension (hereinafter also referred to as UPBE) 8 of the present invention disposed on the upper preheat block base 7.
The upper block 3 (UPBB 7 and UPBE 8) is provided with a first fuel gas ejection passage 9, a shielding oxygen gas ejection passage 11, and a central preheating oxygen gas ejection passage 12. The lower block 4 is provided with a second fuel gas ejection passage 10. Each of these passages allows oxygen gas or fuel gas to pass through and be ejected.
More specifically, the shielding oxygen gas jetting passage 11 is a passage for shielding oxygen gas, and the central preheating oxygen gas jetting passage 12 is a passage for preheating oxygen gas.
Examples of fuel gas include LPG, LNG, and coke gas.

A shoe block 5 is also provided on the underside of the head block 2. A skid 13 is attached to the underside of this shoe block 5. The skid 13 is the part that comes into contact with the steel piece during machining, etc.

Here, the UPBE of the present invention will be described in detail.
3 is a perspective view of the UPBE 8, as seen from the side of the joint surface with the UPBB 7. The orifice plug (hereinafter also referred to as the plug) 14 before being inserted into the oxygen gas ejection passage 11 for shielding is also shown, but the elastic body for fixing the plug is omitted.
FIG. 4 is a rear view of the UPBE 8 with the plug 14 inserted therein.
As shown in Figures 3 and 4, the UPBE 8 is formed with one or more (particularly, a plurality of) shielding oxygen gas ejection passages 11, into each of which a plug 14 for adjusting the flow rate of the shielding oxygen gas can be inserted.

Here, the two plugs for the two shielding oxygen gas ejection passages at both ends are slightly smaller than the seven plugs for the seven shielding oxygen gas ejection passages on the inside. Figure 5 shows the plugs dedicated to both ends (the upper part is a side view, and the lower part is a diagram of the internal structure seen from above). Figure 6 shows the plugs dedicated to the inside (the upper part is a side view, and the lower part is a diagram of the internal structure seen from above).
Each plug 14 has one mounting jig hole 15 in the center, and two orifice holes 16 on either side of it. The mounting jig hole 15 is a screw hole into which the tip (threaded) of a T-shaped mounting jig prepared separately can be inserted, and the mounting jig is inserted into the shielding oxygen gas ejection flow path 11 of the UPBE 8 with the tip of the mounting jig inserted. Note that the mounting jig hole 15 is not a through hole in the plugs dedicated to both ends, and the mounting jig hole 15 is a through hole in the plugs dedicated to the inside (circled area). However, there is no particular limitation, and it may be a through hole or not, and can be determined appropriately.
There is also no particular limitation on the number and the positions of the orifice holes 16. During preheating and laser cutting, the flow rate of oxygen gas is adjusted by the orifice holes 16 and then ejected.

The plug 14 may be detachably fixed in the shielding oxygen gas ejection passage 11 via a plug fixing elastic body, and the specific form is not particularly limited. An example will be described below.
FIG. 7 shows an example of a recess formed on the upper surface of a plug and a state in which a plug-fixing elastic body is fitted into the recess (the upper part is a top view, the middle part is a top view of the fitted state of the plug-fixing elastic body, and the lower part is a side view of the fitted state).
The plug 14 has a circular recess 17 formed on its upper surface (which faces the inner wall of the shielding oxygen gas ejection passage 11 when inserted therein). A plug fixing elastic body (hereinafter also referred to as elastic body) 18 (e.g., an O-ring) can be fitted into this recess 17, and the recess 17 has a depth shallower than the thickness of the elastic body 18. Therefore, when fitted into the recess 17, a part of the elastic body 18 protrudes upward. In this way, the elastic body 18 fitted into the recess 17 when inserted into the shielding oxygen gas ejection passage 11 is unlikely to come off the recess 17, and the protruding part of the elastic body 18 fitted into the recess 17 presses the inner wall of the shielding oxygen gas ejection passage 11 when inserted therein. That is, the plug 14 is firmly fixed inside the shielding oxygen gas ejection passage 11 by the elastic force of the elastic body 18. It can be fixed by a relatively simple mechanism of fitting the elastic body 18 into the recess 17, and since it is not bonded like a liquid gasket, it can be easily removed, making it very simple and convenient.

The thickness of the plug 14, the depth of the recess 17, and the thickness of the elastic body 18 are not particularly limited. They can be determined appropriately depending on, for example, the size of the shielding oxygen gas ejection passage 11, etc.

Since the plug can be fixed via the elastic body 18 without using a liquid gasket, it is possible to prevent the problem that occurred with conventional products in which the liquid gasket was accidentally applied to the side of the plug 14 and the orifice hole 16 was blocked by the liquid gasket. This makes it possible to prevent poor preheating and poor welding caused by such blockage.

In this example, a circular recess 17 is provided on the top surface of the plug 14, but this is not limiting. Instead, it is possible to provide the recess 17 on the bottom surface, or on the side surface on which the orifice hole 16 is not formed, or even on multiple surfaces. The shape of the recess 17 is also not particularly limited, and may be circular, rectangular, triangular, or the like in a plan view. However, for ease of manufacturing and maintenance of such recesses, it is preferable to standardize the location and shape of the recesses in all plugs 14.

In addition, although an O-ring is used as the elastic body 18 here, it is not particularly limited and can be determined appropriately depending on the shape in a plan view of the recess 17, etc. An O-ring is preferable because it is easy to procure.
The material of the elastic body 18 can be, for example, nitrile rubber, which is relatively inexpensive and has excellent abrasion resistance, but is not particularly limited. Any material that is resistant to oxygen gas and heat and has an elasticity sufficient to fix the plug 14 can be used.
The elastic body 18 can be the same as that used for sealing or the like in other parts of the scarf unit 1 of the present invention (for example, the sealing O-ring 21 described later). If such a product is used, it is possible to prevent the number of parts in the scarf unit 1 as a whole from increasing excessively, which is preferable in terms of management and maintenance.

8 shows the internal structure near the UPBE 8 with the plug 14 inserted and fixed. Each jet flow path will be described below.
In the upper block 3 , the oxygen gas ejection passage is branched at the UPBE 8 into two passages, a shielding oxygen gas ejection passage 11 and a central preheating oxygen gas ejection passage 12 .
The above-mentioned plug 14 is inserted into the inside of the shielding oxygen gas ejection passage 11 and fixed via an elastic body 18 , and basically, the shielding oxygen gas is ejected through the orifice hole 16 .
The shielding oxygen gas ejection passage 11 is tapered and has a step 19. This step 19 prevents the plug 14 from advancing any further and ensures a simple sealing performance.
Incidentally, there is no particular problem even if oxygen gas leaks not only from the orifice hole 16 but also from the gap between the inner wall of the shielding oxygen gas ejection flow path 11 and the plug 14 due to the presence of the elastic body 18, and further from the gap between the step 19 and the plug 14. All that is needed is to properly adjust the supply amount of the main oxygen gas so that an appropriate flow rate of shielding oxygen gas can be ejected.

A cylindrical member called an insert 20 having a through hole formed along the central axis is inserted into the UPBE 8, and the through hole serves as a central preheating oxygen gas ejection passage 12 through which preheating oxygen gas can be ejected. A plurality of grooves are formed along the axial direction on the outer periphery of the cylindrical insert 20. A first fuel gas ejection passage 9 is formed so as to surround the insert 20, and fuel gas can be ejected through the gap between the inner wall of the first fuel gas ejection passage 9 and the groove on the outer periphery of the insert 20. A sealing O-ring 21 is provided to prevent the oxygen gas and the fuel gas from mixing inside the UPBE 8.
The mechanism including such an insert 20 allows preheating oxygen gas to be ejected from the center and fuel gas to be ejected concentrically from the outer periphery, making it possible to generate a powerful (high temperature) and long-distance preheating flame.

As mentioned above, the lower block 4 is provided with a second fuel gas ejection passage 10 so that fuel gas can be ejected, and between the upper block 3 and the lower block 4, a cutting oxygen gas ejection slot 6 is provided so that cutting oxygen gas can be ejected.

Next, a method for assembling the UPBE and scarf unit of the present invention will be described.
Here, an O-ring is used as the elastic body 18, and a plug 14 having a recess 17 on its upper surface as shown in Figs. 3 and 7 is inserted and fixed in the UPBE8, but the present invention is not limited to this. Any method may be used as long as the orifice plug is detachably fixed in the shielding oxygen gas ejection flow passage via an elastic body for fixing the plug.

First, the elastic body 18, which is an O-ring, is fitted into the recess 17 of the plug 14. With the elastic body 18 still fitted into the recess 17, the plug 14 is inserted using an attachment jig up to the step 19 inside the shielding oxygen gas ejection passage 11 of the UPBE8. The elastic force of the elastic body 18 presses against the inner wall of the shielding oxygen gas ejection passage 11, so that the plug 14 is firmly fixed inside. In this manner, the UPBE8 is assembled.

Next, the upper block 3 and the lower block 4 are disposed on the front side of the head block 2. At this time, they are disposed with a gap between them to form an oxygen gas ejection slot 6 for surface cutting.
Furthermore, when the upper block 3 is disposed, for example, the UPBB 7 of the upper block 3 may first be disposed relative to the head block 2, and then the UPBE 8 may be disposed relative to the UPBB 7. Alternatively, the UPBB 7 and the UPBE 8 may be joined to assemble the upper block 3, and then the upper block 3 may be disposed relative to the head block 2.
In addition, a shoe block 5 is disposed on the lower surface side of the head block 2 .
In this manner, the scarf unit 1 is assembled.

The assembly method of the present invention described above allows for easy assembly in a short time, and disassembly is also very simple.

A method of performing thermal cutting using the scarf unit 1 of the present invention will be described below. For simplicity, an example will be described in which the scarf unit 1 is disposed only on the front surface side (upper surface side) of a steel billet. However, the present invention is not limited to this, and it is also possible to dispose the scarf unit on two or four surfaces of the steel billet and perform thermal cutting on two or four surfaces of the steel billet at the same time.
First, the steel billet is placed on a roller table for feeding the billet, and is transported toward the scarf unit 1. At this time, the scarf unit 1 is disposed at a position sufficiently above the roller table and the billet.
After the end of the steel piece has been transported below the scarf unit 1, the scarf unit 1 is moved toward the steel piece (in this case, lowered) so that the skid 13 comes into contact with the surface (top) of the steel piece (closing process).

After contact, the scarf unit 1 is moved away from the surface of the piece of steel. This distance can be approximately 1/2 inch (about 12.5 mm). The piece of steel is then pulled slightly (i.e., transported away from the scarf unit 1) by the roller table, and positioned so that the preheating flame from the scarf unit 1 hits the edge of the surface of the piece of steel in the next preheating process.

Next, while the skid 13 is not in contact with the surface of the billet, fuel gas is ejected at low speed from the first fuel gas ejection passage 9, fuel gas is ejected at high pressure from the second fuel gas ejection passage 10, low pressure oxygen gas is ejected from the shielding oxygen gas ejection passage 11, oxygen gas is ejected at high speed from the central preheating oxygen gas ejection passage 12, and oxygen gas is ejected at low speed from the cutting oxygen gas ejection slot 6, all of which are ignited by an igniter to generate a preheating flame and generate molten slag on the surface of the billet (preheating process). The preheating flame at this time is a linear concentrated flame in the width direction of the billet.
The preheating time may be, for example, about 5 seconds if the steel piece is a hot piece, and about 60 seconds if the steel piece is a cold piece.

After the molten slag is generated, the gas flow rate is switched from the preheating flame to the cutting flame. That is, a large flow rate (e.g., about 200 kPa) of oxygen gas is ejected from the oxygen gas ejection slot 6 for cutting, while a small flow rate of oxygen gas is ejected from the oxygen gas ejection passage 11 for shielding and the oxygen gas ejection passage 12 for central preheating only to protect the ejection nozzles, and a small flow rate of fuel gas is ejected from the first fuel gas ejection passage 9 and the second fuel gas ejection passage 10. At the same time, the scarf unit 1 is moved (lowered) toward the steel piece, and the skid 13 is brought into contact with the surface of the steel piece, while the roller table transports the steel piece toward the scarf unit 1. In this way, a large amount of oxygen is sprayed onto the molten slag while the steel piece is advanced toward the scarf unit 1, and the surface of the steel piece can be cut one after another while generating molten slag due to an oxidation reaction (cutting process).

Although the billet has warping or bending, by performing the scouring while bringing the skid 13 of the scarf unit 1 into contact with and intimately contacting the surface of the billet as described above (i.e., by performing the scouring while keeping the distance between the scarf unit 1 and the billet constant), the scouring allowance can be made uniform over the entire scouring surface of the billet. This scouring allowance can be, for example, about 1.5 to 4 mm.
During the thermal cutting, high-pressure water from the high-pressure water nozzle can be used to blow away unwanted molten slag toward the inner wall of the smoke hood that surrounds the steel piece while thermal cutting is being performed.
By the above-described laser cutting process, a laser cut product can be obtained.

The present invention will be described in more detail below with reference to examples and comparative examples of the present invention, but the present invention is not limited to these.
(Example)
Using the UPBE assembly method of the present invention, an orifice plug was inserted and fixed inside the oxygen gas jet passage for shielding of the UPBE for the scarf unit, and the UPBE was assembled. After assembly, the UPBE was disassembled and the orifice plug was taken out from inside. The time required for this assembly and disassembly was measured.
The orifice plug used had a recess on its upper surface as shown in Figure 7. During assembly, an O-ring made of nitrile rubber was fitted into the recess and inserted into the inside of the oxygen gas ejection flow path for shielding using a mounting jig, and the O-ring was fixed in place by its elasticity.
Conversely, the orifice plug inside the oxygen gas ejection passage for shielding was pulled out using a mounting jig, and disassembly was performed. The O-ring could be easily removed from the recess of the pulled out orifice plug.

(Comparative Example)
Using a conventional UPBE assembly method, an orifice plug was inserted and fixed inside the oxygen gas jet passage for shielding of the UPBE for the scarf unit, and the UPBE was assembled. After assembly, the UPBE was disassembled and the orifice plug was removed from inside. The time required for this assembly and disassembly was measured.
The orifice plug used was the same as in the conventional example, but without a recess on the upper surface. During assembly, a liquid gasket (silicone-based) was applied to the upper surface, and the orifice plug was inserted into the inside of the oxygen gas ejection flow passage for shielding using a mounting jig. The orifice plug was then left in that state to allow the liquid gasket to dry and be fixed in place.
Conversely, the orifice plug inside the oxygen gas ejection passage for shielding was pulled out using a mounting jig and disassembled. Dried liquid gasket was found to be attached to both the top surface of the pulled-out orifice plug and the inner wall of the oxygen gas ejection passage for shielding, so this was removed. Specifically, most of the liquid gasket residue attached to these was first scraped off using a knife, and any remaining residue was removed using a brass spiral brush. For the orifice plug, a pin vice was used to remove any clogging in the orifice hole.

When the time required for assembly and disassembly was compared, it took 180 minutes for the comparative example, whereas assembly took only 5 minutes for the example. This is because the comparative example required a long time for the liquid gasket to dry. On the other hand, such drying was not necessary for the example, and as a result, the time was shortened by 175 minutes compared to the comparative example.
Also, in terms of disassembly, the Comparative Example took 20 minutes, whereas the Example took only 5 minutes. This is because the Comparative Example required time to remove the liquid gasket. However, the Example did not require such removal work, and as a result, the disassembly time was shortened by 15 minutes compared to the Comparative Example.

The present invention, as shown in the examples, was able to reduce the time required to assemble and disassemble the UPBE, and therefore also significantly reduced the overall time required to assemble and disassemble the scarf unit.

When multiple UPBEs were assembled using the same procedure as in the comparative example, there were cases where liquid gasket was mistakenly applied to the orifice hole in addition to the top surface. With the present invention as in the examples, such mistakes do not occur, making it safer.

The present invention is not limited to the above-mentioned embodiment. The above-mentioned embodiment is merely an example, and anything that has substantially the same configuration as the technical idea described in the claims of the present invention and has similar effects is included within the technical scope of the present invention.

1... scarf unit of the present invention, 2... head block, 3... upper block,
4...Lower block; 5...Shoe block; 6...Oxygen gas ejection slot for machining;
7...Upper preheat block base,
8...Upper preheat block extension of the present invention,
9...first fuel gas ejection passage, 10...second fuel gas ejection passage,
11... Shielding oxygen gas ejection passage, 12... Center preheating oxygen gas ejection passage,
13...skid; 14...orifice plug; 15...hole for mounting jig;
16: orifice hole; 17: recess; 18: plug fixing elastic body;
19...step, 20...insert, 21...sealing O-ring.

Claims (10)

An upper preheat block extension for a scarf unit for scarfing an object to be scarfed, comprising:
the upper preheat block extension has a shielding oxygen gas ejection passage for ejecting shielding oxygen gas and a central preheating oxygen gas ejection passage for ejecting preheating oxygen gas,
an orifice plug for adjusting a flow rate of the shielding oxygen gas is inserted into the inside of the shielding oxygen gas ejection passage and detachably fixed thereto;
The orifice plug is fixed via an elastic body for fixing the plug. the orifice plug has a recess on an upper surface facing an inner wall of the shielding oxygen gas ejection passage, the recess being shallower than a thickness of the plug fixing elastic body,
2. The upper preheat block extension according to claim 1, wherein the orifice plug is inserted and fixed in place with the plug fixing elastic body fitted in the recess. The upper preheat block extension according to claim 1 or 2, characterized in that the plug fixing elastic body is an O-ring. The upper preheat block extension according to any one of claims 1 to 3, characterized in that the plug fixing elastic body is made of nitrile rubber. A scarf unit for melt-cutting an object to be melt-cut, comprising: a head block; an upper block having a first fuel gas ejection passage, a shielding oxygen gas ejection passage, and a central preheating oxygen gas ejection passage; a lower block having a second fuel gas ejection passage; and a shoe block that comes into contact with the object to be melt-cut,
The upper block and the lower block are disposed on the front side of the head block so as to define a space between them to form an oxygen gas ejection slot for use in cutting, and the shoe block is disposed on the underside of the head block,
A scarf unit characterized in that the upper block has an upper preheat block base arranged on the head block and an upper preheat block extension described in any one of claims 1 to 4 arranged on the upper preheat block base. A method for assembling an upper preheat block extension for a scarf unit that scarves an object to be scarified, comprising the steps of:
A method for assembling an upper preheat block extension, characterized in that when an orifice plug for adjusting the flow rate of the shielding oxygen gas is inserted and removably fixed inside a shielding oxygen gas ejection passage in the upper preheat block extension for ejecting the shielding oxygen gas, the orifice plug is fixed via an elastic body for fixing the plug. When the orifice plug is fixed,
In the orifice plug, a recess is formed on an upper surface facing an inner wall of the shielding oxygen gas ejection passage, the recess being shallower than a thickness of the plug fixing elastic body;
7. The method for assembling an upper preheat block extension as described in claim 6, characterized in that the orifice plug is fixed by inserting it into the inside of the shielding oxygen gas ejection passage with the plug fixing elastic body fitted into the recess. The method for assembling an upper preheat block extension according to claim 6 or 7, characterized in that the plug fixing elastic body is an O-ring. The method for assembling an upper preheat block extension according to any one of claims 6 to 8, characterized in that the plug fixing elastic body is made of nitrile rubber. A method for assembling a scarf unit for melt-cutting an object to be melt-cut, the scarf unit having a head block, an upper block having a first fuel gas jet passage, a shielding oxygen gas jet passage and a central preheating oxygen gas jet passage, a lower block having a second fuel gas jet passage, and a shoe block that comes into contact with the object to be melt-cut, comprising:
The upper block and the lower block are disposed on the front side of the head block so as to define a space between them to form an oxygen gas ejection slot for surface cutting, and the shoe block is disposed on the underside of the head block.
A method for assembling a scarf unit, comprising disposing the upper block using an upper preheat block base to be disposed on the head block and an upper preheat block extension assembled by the upper preheat block extension assembly method described in any one of claims 6 to 9.