KR20060115983A - Manufacture method of recuperator and thereof product - Google Patents

Abstract

A recuperator manufacturing method and a recuperator produced by the same are provided to cast the complicated recuperator at high precision without forming parting lines on the surface and to improve production efficiency by executing continuous casting. The recuperator manufacturing method comprises the steps of: forming an inner core and an outer mold frame by processing metal correspondently to the shape of a cylindrical recuperator having plural fins on the inner peripheral surface(S1); injecting wax after assembling the inner core and the outer mold frame(S2); forming a tree by sticking plural waxes to a sprue(S3); forming a mold by coating the outside of the tree with ceramic refractory materials and then drying the tree(S4); melting and removing the wax by heating the mold by hot steam(S5); removing the remaining materials by heating the mold at high temperature(S6); injecting melt into the mold(S7); removing the coating material applied on the outside of the mold(S8); cutting plural castings stuck on the tree(S9); thermally treating the casting(S10); smoothly processing the outside of the casting and checking defects(S11); connecting the castings produced correspondently to each part by welding(S12); and examining the finished recuperator(S13).

Description

Manufacturing method of a recuperator and a recuperator manufactured by the same {manufacture method of recuperator and pretty product}

1 is a flow chart showing a manufacturing process of the recuperator according to the present invention.

2 is a diagram of a recuperator manufactured according to the present invention.

<Description of Symbols for Main Parts of Drawings>

S1 to S13: Step 1 to Step 13 A: Recuperator

a01, a02,... Casting

The present invention relates to a manufacturing method of a recuperator used for waste heat recovery, and more particularly, to manufacture a recuperator for improving the production efficiency by maximizing the dimensional accuracy of the casting and the smoothness of the casting process. It relates to a method and a recuperator manufactured thereby.

In general, a large amount of energy consumed in industrial facilities may be steel and non-ferrous metal manufacturing related equipment, and among them, various industrial furnaces such as heating furnace, heat treatment furnace, melting furnace is a representative energy consumption equipment.

Most industrial furnaces except for those using electricity among the various industrial furnaces for metal production employ a method of obtaining energy by burning petroleum gas, diesel oil, bunker seed oil or refined waste oil, and the combustion of a burner that burns the fuel. In order to increase efficiency, it is necessary to preheat the combustion air supplied to the burner.

Accordingly, various industrial furnaces are equipped with a device called a recuperator which recovers and uses waste heat of exhaust gas discharged in a hot state to heat combustion air supplied to a burner. Although there are two types, the radiation type recuperator used for the waste heat recovery from the high-temperature exhaust gas generated in a normal industrial furnace has a shape in which a plurality of fins are formed on the inner circumferential surface of the cylindrical tube.

Looking at the manufacturing method of the conventional radiation recuperator, the step of manufacturing the inner core by processing the wooden die, the step of manufacturing the upper and lower outer mold in a wooden mold, and inserting the inner core into the lower outer mold, and then the upper outer Assembling the mold, injecting molten metal into the space inside the assembled inner core and the outer mold, detaching the casting by separating the outer mold, and smoothly processing the surface of the demolded casting to obtain a finished product. Is done.

Here, the inner core is made to be divided into four to be combined.

However, this conventional technology is inconvenient to move due to the heavy weight of the mold made of a wooden mold, and is cast by the combination of the upper and lower outer mold, so that a dividing line is formed on the surface of the casting, so that it is not smooth. There was a problem that the dimensions are incorrect because the do not form an accurate circle.

The present invention has been made to solve the above-mentioned problems of the prior art, by increasing the accuracy of the dimensions by manufacturing the accumulator by precision casting, by using a lightweight mold to facilitate the casting operation to improve the production efficiency It is an object of the present invention to provide a method for manufacturing a recuperator and a recuperator manufactured thereby.

The present invention to achieve the above object,

A first step of manufacturing an inner core and an outer mold by processing a metal to conform to a shape of a recuperate having a cylindrical shape and having a plurality of pins formed on an inner circumferential surface thereof; Assembling the inner core and the outer mold and injecting wax; Three steps of making a tree by bonding a plurality of waxes to the hot water; A four step of manufacturing a mold by coating the outer surface of the tree with a refractory material of ceramic material and then drying it; 5 steps of melting the wax by heating the mold to a low temperature with a high temperature steam; Heating the mold to a high temperature to remove residues; 7 steps of injecting molten metal into the mold; An eight step of removing the coating material outside the mold; 9 steps of cutting a plurality of castings attached to the tree; 10 steps of heat-treating the casting; An eleven step of smoothly processing the outer surface of the casting and checking for defects; 12 steps of connecting and casting the castings produced for each part; And 13 steps of inspecting the final completed recuperator.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In the accompanying drawings, Figure 1 is a flow diagram showing a manufacturing process of the recuperator according to the present invention.

2 is a diagram of a recuperator manufactured according to the present invention.

As shown in Figures 1 to 2, the manufacturing method of the recuperator according to the present invention, the inner core and the outer mold by manufacturing a metal to conform to the shape of the recuperate cylindrical and a plurality of pins formed on the inner peripheral surface One step (S1) and; Assembling the inner core and the outer mold and injecting wax (S2); Step 3 (S3) for producing a tree by bonding a plurality of wax to the spout; A fourth step (S4) of manufacturing a mold by coating the outer surface of the tree with a refractory material of ceramic material and then drying it; 5 steps (S5) of melting the wax by heating the mold to a low temperature with a high temperature steam; Heating the mold to a high temperature to remove residues (S6); 7 steps (S7) of injecting the molten metal into the mold; Eight steps (S8) for removing the coating material on the outside of the mold; 9 steps (S9) of cutting a plurality of castings attached to the tree; 10 steps (S10) for heat-treating the casting; An eleven step (S11) of smoothly processing the outer surface of the casting and checking whether there is a defect; 12 steps (S12) for welding and connecting the castings produced for each part; It consists of 13 steps (S13) to inspect the final completed recuperator.

In more detail,

Step 1 (S1)

Using a lightweight and easy-to-process aluminum, molds are produced by calculating the expansion and shrinkage rates at high and low temperatures.

That is, a plurality of pins are formed on the outer surface of the aluminum to produce a cylindrical inner core. In addition, a hollow is formed on the inside, and a plurality of pins are inserted into the pin and the male and female of the inner core on the inner circumferential surface of the hollow to manufacture the outer mold.

Step 2 (S2)

The wax is injected into the mold assembled by inserting the inner core into the outer mold.

The properties of the wax material should be stable and not deformed when handled at room temperature. Low-melting wax is used that does not leave ash when heated to 1000 ℃.

In addition, it should be a low melting temperature range of 60 ~ 80 ℃, a low operating temperature of about 60 ℃, to maintain the strength without softening at room temperature, has a clean and smooth surface and is well separated from the mold, and possibly shrink, The coefficient of expansion should be small.

Wax is injected into the mold in a semi-flow state. The wax is reused in most of the recovered by the five steps described later, but the recovered is used after the purification process because it contains a somewhat solid. At this time, the temperature to be purified is maintained at 105 ℃ ± 10 ℃.

After repeated use, the properties of the wax were slightly degraded, so a little amount of new wax was added.

The temperature control of the wax used is controlled to 55 ℃ ± 5 ℃, and the injected wax is placed in a horizontal flat place.

Step 3 (S3)

Pre-producing the tapping and pressing water, and joining a plurality of the wax injected in the step 2 to the molten ball to produce a tree.

Place the tang on the support and melt the bonded tang and tang by using a bullet heated to 300 ℃ ± 40 ℃.

Step 4 (S4)

The outer surface of the tree is coated with a refractory material of ceramic material and then dried.

First, foreign matter is removed by spraying air onto the mold assembled in the step 2 before coating.

Thereafter, the refractory material in the form of slurry is coated on the outside of the mold over several times to complete the mold, but more accurate examples are shown in the following table.

Slurry Division The time when the liquid comes out Usage Standard (water use) 6.7 seconds to 7 seconds Primary slurry 37 to 41 seconds Heat-resistant steel 44 to 47 seconds Cast steel, stainless 2 to 3 slurry 11 to 13 seconds Public 4-8th slurry 9 to 10 seconds Public

SiO ₂ is used as the slurry, the temperature of the coating chamber is 250 ℃ ± 3 ℃, the humidity is preferably 65 ℃ ± 7%.

In casting of a high melting point alloy such as alloy steel, first, a thinly coated backside yarn, which is a fine powder of a refractory material, is coated. The refractory material is a fine powder as much as possible, a high fire resistance is suitable, and zircon yarn is used.

Soak the mold for about 1 minute, take it out, remove the air bubbles, and dry by spraying a backing thread.

At this time, vibration is applied during the immersion operation so that the air bubbles do not adhere.

Step 5 (S5)

A dewaxing step of melting the wax by heating the mold with low temperature steam.

That is, the mold is placed upside down and displayed inside the dewaxing machine, the door of the dewaxing machine is sealed, and steam at 150 ° C. ± 15 ° C. is injected for 15 minutes in an atmosphere of 7.5 ± 0.5 kg / cm 2.

After dewaxing the molds are inspected and the cracks are repaired with homogeneous materials.

Step 6 (S6)

The dewaxed mold is heated again to a high temperature to remove the residue.

About 85% of the wax usage is recovered in the dewaxing operation, but the remaining wax adheres to the inner surface of the mold by surface tension or penetrates into the mold by capillary action.

Therefore, in order to remove the wax remaining in the mold, the mold is charged and calcined in a firing furnace, and heated to 600 to 700 ° C., and the firing cycle is 90 minutes ± 10 minutes.

Step 7 (S7)

Fill the mold as quickly as possible while the flow of the melt is quiet.

Step 8 (S8)

The casting is extracted by removing the refractory material coated on the outside of the mold.

Step 9 (S9)

A plurality of castings attached to the tree are cut one by one.

10 to 13 steps (S10 to S13)

Heat-treat the casting to stabilize the structure, smoothly process the outer surface of the casting, check for defects, and weld the castings (a1, a2, ...) manufactured for each part to connect the final recuperator (A). After assembly, inspect the weld.

Welding is butt welding, and the atmosphere is made of argon gas to improve the efficiency.

According to the present invention configured as described above, it is possible to cast a high-precision complex shape accumulator, to make a clean product without a dividing line on the surface, and continuous casting is possible, thereby improving the production efficiency. have.

Claims (6)

A first step of manufacturing an inner core and an outer mold by processing a metal to conform to a shape of a recuperate having a cylindrical shape and having a plurality of pins formed on an inner circumferential surface thereof; Assembling the inner core and the outer mold and injecting wax; Three steps of making a tree by bonding a plurality of waxes to the hot water; A four step of manufacturing a mold by coating the outer surface of the tree with a refractory material of ceramic material and then drying it; 5 steps of melting the wax by heating the mold to a low temperature with a high temperature steam; Heating the mold to a high temperature to remove residues; 7 steps of injecting molten metal into the mold; An eight step of removing the coating material outside the mold; 9 steps of cutting a plurality of castings attached to the tree; 10 steps of heat-treating the casting; An eleven step of smoothly processing the outer surface of the casting and checking for defects; 12 steps of connecting the castings produced for each site by site; Inspecting the final completed recuperator; Method for manufacturing a recuperator comprising a. The method of claim 1, The fourth step is a method of manufacturing a recuperator, comprising the step of removing foreign matter by spraying air to the mold assembled in the second step before coating. The method of claim 1, The refractory material of step 4 is SiO ₂ in the form of a slurry, the temperature of the coating chamber is 250 ℃ ± 3 ℃, humidity is 65 ℃ ± 7% manufacturing method of the recuperator. The method of claim 1, The fifth step is a method of manufacturing a recuperator, characterized in that for 15 minutes injecting steam at 150 ℃ ± 15 ℃ in 7.5 ± 0.5 kg / ㎠ atmosphere for 15 minutes. The method of claim 1, In step 6, the mold is charged to a kiln and fired at 600 to 700 ° C., and the firing cycle is 90 minutes ± 10 minutes. The recuperator manufactured by the manufacturing method in any one of Claims 1-5.

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