JP6368292B2 - Membrane structure duct manufacturing method - Google Patents

Description

  The present invention relates to a method of manufacturing a duct, particularly a membrane structure duct used for recovering or dissipating exhaust gas generated in a converter, for example.

In many cases, an exhaust gas recovery (or emission) duct of a steel refining facility represented by a converter has a water-cooled structure because it is intended for high-temperature gas.
The water cooling structure of this duct includes what is called a membrane structure in which water pipes (boiler tubes) are welded together via a joining member made of a steel plate.
When exhaust gas from refining equipment contains a lot of corrosive components or wearable particles, the surface (gas passage surface) of the above-mentioned membrane structure duct (water cooling) is subjected to thermal spraying or overlay welding in order to form a protective layer Things have been done.
For example, Patent Document 1 discloses the thermal spraying, and Patent Document 2 discloses the overlay welding.

JP 2001-280858 A JP 2010-235982 A

  When the protective layer is formed by thermal spraying, the protective layer can be formed thin and does not reduce the cooling effect of the water pipe and the joining member by the cooling medium. It tends to peel off and tends to shorten its life.

On the other hand, when the protective layer is formed by overlay welding, the protective layer has a greater bonding force with the water pipe and the joining member and has a longer life than the case where it is formed by thermal spraying. There is a problem that the cooling effect of the water pipe and the joining member by the working medium is reduced.
In addition, since the surface of overlay welding is not a smooth surface, irregularities are formed, so the amount of heat removal differs between the concave and convex portions, thermal stress is generated, and cracks are likely to occur on the surface of the protective layer. In addition, the concavo-convex portion also has a problem that stress is easily concentrated and can be a starting point of a crack.

  In order to avoid this problem, when forming a protective layer by overlay welding, conventionally, in order to make the thickness of the protective layer thin and the same at any part, for example, grinding was manually performed using a grinder or the like. . For this reason, there is a problem that the time required for grinding becomes longer and costs are increased.

  The present invention has been made in order to solve such problems, and has a membrane structure capable of efficiently producing a membrane structure duct having a long life and a protective layer in which thermal stress and cracks are unlikely to occur. It aims at providing the manufacturing method of a duct.

(1) The manufacturing method of the membrane structure duct according to the present invention includes a panel body forming step of forming a flat panel body by joining a plurality of water tubes in parallel via a plate-like joining member;
A protective layer forming step of forming a protective layer by performing overlay welding on the surface of the panel body;
A panel body on which a protective layer is formed is fixed on a table of a planer, and a grinding tool having a shape along the surface shape of the panel body is moved relative to the panel body in a direction along the axis of the water pipe. A grinding step of flattening the surface of the overlay welding by allowing
A panel body joining step for forming a membrane structure duct by joining a plurality of panel bodies that have been flattened in the grinding step so that the flattened surface is on the gas passage side. It is what.

(2) In the above described (1), the grinding tool has a first tool having a shape along the arc part of the water pipe, and a second tool having a shape along the groove part between the water pipe and the water pipe. It is composed of bytes.

(3) In the above (1) or (2), the grinding tool is provided with a roughing cutting tool and a finishing cutting tool installed in series in the grinding direction. It is.

  In the present invention, a panel body forming step of forming a flat panel body by joining a plurality of water pipes in parallel via a plate-like joining member, and overlay welding is performed on the surface of the panel body A protective layer forming step of forming a protective layer, and fixing the panel body on which the protective layer is formed on a table of a planing machine, a grinding tool having a shape along the surface shape of the panel body is attached to the panel body. A grinding process for planing the surface of the build-up welding by relatively moving in a direction along the axis of the water pipe, and a plane obtained by planing a plurality of panel bodies planed by the grinding process With a panel body joining step that forms a membrane structure duct by joining so that the gas passage is on the gas passage side, and the surface of the overlay welding can be smoothed efficiently and almost uniformly, so the life is long. , Generation of thermal stress The or cracks membrane structure duct generation hardly occurs protective layer is formed of can be efficiently produced.

It is explanatory drawing of the process of the manufacturing method of the membrane structure duct which concerns on one embodiment of this invention. It is explanatory drawing explaining the state of the workpiece of each process in the manufacturing method of the membrane structure duct which concerns on one embodiment of this invention. It is explanatory drawing explaining the grinding process in the manufacturing method of the membrane structure duct which concerns on one embodiment of this invention. It is an arrow AA figure of FIG. It is explanatory drawing of the 1st byte which concerns on one embodiment of this invention. It is explanatory drawing of the grinding method by the 1st cutting tool which concerns on one embodiment of this invention. It is explanatory drawing of the 2nd byte which concerns on one embodiment of this invention. It is explanatory drawing of the grinding method by the 2nd cutting tool which concerns on one embodiment of this invention. It is explanatory drawing of the panel body joining process in the manufacturing method of the membrane structure duct which concerns on one embodiment of this invention. It is explanatory drawing of the other aspect of the grinding tool which concerns on one embodiment of this invention. It is explanatory drawing explaining the detail of the grinding tool shown in FIG. It is explanatory drawing of the planer used for the grinding method which concerns on other embodiment of this invention. It is explanatory drawing of the grinding method which concerns on other embodiment of this invention, and is a figure which shows the state which planarly viewed the grinding | polishing site | part. It is explanatory drawing of the grinding method which concerns on other embodiment of this invention, and is a figure which shows the state which looked at the grinding site | part from the side.

[Embodiment 1]
As shown in FIG. 1, the method for manufacturing a membrane structure duct according to an embodiment of the present invention includes a panel body forming step, a protective layer forming step, a grinding step, and a panel body joining step.
Hereinafter, each process will be described in detail.

<Panel body forming process>
As shown in FIG. 2A, the panel body forming step is a step of forming a flat panel body 5 by joining a plurality of water tubes 3 in parallel via a plate-like joining member 1.
The plurality of water pipes 3 and the joining member 1 are joined by fillet welding 7.
The width and length of the panel body 5 may be appropriately set according to the shape of the membrane structure duct to be formed. For example, as described later, when the panel body 5 is bent along the water pipe 3 to manufacture a cylindrical membrane structure duct, the panel body 5 is formed wide.

<Protective layer forming step>
The protective layer forming step is a step of forming the protective layer 9 by performing overlay welding on the surface of the panel body 5. The surface of the panel body 5 here is a surface on the duct inner surface side through which gas passes when the membrane structure duct is formed.
By forming the protective layer 9 by overlay welding, the bonding strength of the protective layer 9 to the water pipe 3 and the joining member 1 is large, and the life is longer than that of the protective layer 9 by thermal spraying.
In addition, at the time of completion of a protective layer formation process, as shown in FIG.2 (b), the surface of build-up welding is the state in which the unevenness | corrugation was formed instead of a smooth surface.

<Grinding process>
The grinding process is a process of planing the surface of overlay welding in the panel body 5 formed in the protective layer forming process, and is specifically performed as follows.
As shown in FIGS. 3 and 4, the panel body 5 on which the protective layer 9 is formed is fixed on the table 13 of the planer 11, and a grinding tool 15 having a shape along the surface shape of the panel body 5 is provided. The surface of the overlay welding is planed by moving the panel body 5 in the direction along the axis of the water tube 3 relative to the panel body 5.

  In the present invention, when the membrane structure duct 21 is manufactured, the flat panel body 5 is first formed, so that machining with the planer 11 is possible. Further, the surface of the panel body 5 that is the target of the planing process is a linear shape along the water pipe 3, and this is also suitable for the processing with the planing machine 11.

The grinding tool 15 will be described.
In the grinding tool 15 of the present embodiment, two types of tools are used. As shown in FIG. 5, the first cutting tool 17 has a first cutting edge 17 a whose tip is a convex arc, and as shown in FIG. 6, the flesh of the groove between adjacent water pipes 3 is formed. Used to grind prime welds.
The first cutting tool 17 is constituted by a hail cutting tool having a first shank 17b whose neck is bent so as to move in a spring in order to avoid biting and chatter.

As shown in FIG. 7, the second cutting tool 19 has a second cutting edge 19a whose tip is a concave arc, and as shown in FIG. Use to do.
The second bite 19 is constituted by a hail bite having a second shank 19b whose neck is bent so as to move in the spring in order to avoid biting and chattering, like the first bite 17.

FIG. 1C shows a state where the surface of the overlay welding is smoothed by the grinding process. Thus, by smoothing the surface of overlay welding, generation of thermal stress can be prevented and generation of cracks can be prevented.
In particular, since machining by the planer 11 is performed, the time required for smoothing can be remarkably shortened and costs can be reduced as compared to manual work using a grinder. Further, since the protective layer 9 can be made thin and substantially uniform, it is excellent in corrosion resistance and wear resistance, and generation of thermal stress can be suppressed.

<Panel body joining process>
In the panel body joining step, as shown in FIG. 9, the plurality of panel bodies 5 that have been flattened in the grinding step are joined so that the flattened surface is on the gas passage side, and the membrane structure duct 21 is joined. Is a step of forming.
FIG. 9 shows an example in which four panel bodies 5 are joined to form a rectangular membrane duct.

According to the present embodiment, the protective layer 9 by overlay welding is formed on the panel body 5 formed in a flat plate shape, and the protective layer 9 is uniformly processed by the planer 11 so that the protective layer 9 is protected. The unevenness of the layer 9 is smoothed, so that generation of thermal stress can be prevented and cracking can be prevented.
And in the grinding process, since the overlay welding is smoothed by the planer 11, the working efficiency is remarkably improved.

In the above embodiment, an example is shown in which four panel bodies 5 are joined in a rectangular shape. However, the number of panel bodies 5 to be joined in the panel body joining step of the present invention is not limited to four. For example, five panel bodies 5 may be joined to form a membrane structure duct having a pentagonal cross section.
Further, after forming the wide panel body 5 in the panel body forming process and smoothing the overlay welding by the grinding process, the panel body 5 is bent along the water pipe 3 to form a cylindrical membrane structure duct. Also good.
The reason why such a large number of panel bodies 5 and wide panel bodies 5 can be formed is that the grinding process is machined by the planer 11 so that the overlay welding can be efficiently ground. It is an effect.

  In the above embodiment, the case where two types of cutting tools are used as the grinding tool has been described. However, the present invention is not limited to this, and as shown in FIG. It may be a grinding tool 23 capable of grinding at least half of the ridges simultaneously.

The shape of the cutting tool of the grinding tool 23 will be described with reference to FIGS.
The grinding tool 23 is axisymmetric, and FIG. 11 shows the shape of a half of a cutter. As shown in FIG. 11, the blade has a concave arc portion 23a, a central flat portion 23b serving as a portion for grinding a central groove portion, and a central flat portion 23b and a concave arc portion 23a that are smooth with a circumscribed circle. The connecting arc portion 23c to be connected is provided. Hereinafter, specific dimensions of the edge shape will be described in detail.

As shown in FIG. 10B, the distance between the centers of the adjacent water pipes 3 is P, the radius of the water pipe 3 is r, the thickness of the joining plate is h, and the thickness of the overlay welding to be left as the protective layer 9 is t. To do.
As shown in FIG. 11, the width W of the blade is W> P. Thereby, uncut portions can be prevented. The radius R of the concave arcuate portion 23a of the blade is R = r + t.
The length X of the central flat portion 23b is set to 0 <X / 2 <(W / 2) -R. Further, the radius S of the circumscribed circle constituting the connecting arc portion 23c is set to S> 10 mm in order to avoid stress concentration.

[Embodiment 2]
The present embodiment will be described with reference to FIGS.
In the present embodiment, the grinding process performed by the planer 11 is performed by placing two cutting tools 23A for rough cutting and a cutting tool 23B for finishing in series in the grinding direction.
The shape of the cutting tool is the same as that described as another aspect of the first embodiment as shown in FIG.

When the cutting tool 23A for rough cutting and the cutting tool 23B for finishing are arranged in series in the grinding direction and ground, as shown in FIG. 14, after rough cutting with the cutting tool 23A, finish cutting is continuously performed with the cutting tool 23B at a time. It can be carried out.
By doing in this way, the grinding surface can be ground to a smoother and more uniform thickness compared with the case where the necessary thickness C is ground at one time with one bite, and the generation of thermal stress and cracks Can be prevented more reliably.
Moreover, since it can carry out by one grinding process, grinding efficiency does not fall.

The aspect in which the cutting tool for rough cutting and the cutting tool for finishing are placed in series and the grinding process is performed can also be applied to the case where the two types of tools shown in FIGS. 5 and 7 are used.
In this case, the first tool for roughing and the first tool for finishing are placed in series as the first tool, and the second tool for roughing and the second tool for finishing are used as the second tool. It may be installed in series.

DESCRIPTION OF SYMBOLS 1 Joining member 3 Water pipe 5 Panel body 7 Fillet weld 9 Protective layer 11 Planer 13 Table 15 Grinding tool 17 1st cutting tool 17a 1st cutting edge 17b 1st shank 19 2nd cutting tool 19a 2nd cutting edge 19b 2nd shank 21 Membrane structure duct 23 Grinding tool (other modes)
23a Concave arc part 23b Central flat part 23c Connection arc part 23A Roughing tool 23B Finishing tool

Claims (2)

A panel body forming step of forming a flat panel body by joining a plurality of water pipes in parallel via a plate-like joining member;
A protective layer forming step of forming a protective layer by performing overlay welding on the surface of the panel body;
A panel body on which a protective layer is formed is fixed on a table of a planer, and a grinding tool having a shape along the surface shape of the panel body is moved relative to the panel body in a direction along the axis of the water pipe. A grinding step of flattening the surface of the overlay welding by allowing
A plurality of panel bodies that have been flattened in the grinding step, and a panel body joining step that forms a membrane structure duct by joining the flattened surfaces on the gas passage side,
The grinding tool, said the blade shape, and a concavely curved portion of grinding the ridges of the panel body, and a central flat portion serving as a site of grinding a groove in the center of the path, channel member, with the central flat portion Manufacturing of a membrane structure duct characterized by comprising a connecting arc portion that smoothly connects concave arc portions with a circumscribed circle, and capable of simultaneously grinding at least half of the groove portion of the panel body and the crest portions on both sides thereof. Method.   2. The method for manufacturing a membrane structure duct according to claim 1, wherein the grinding tool includes a roughing cutting tool and a finishing cutting tool installed in series in a grinding direction.