JP3015778B2 - Manufacturing method of clad tube by coextrusion method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a co-extrusion method (Co-
The present invention relates to a method of manufacturing an aluminum clad tube for a vaporizer by extrusion, and more particularly, to fixing a clad for coating a tube through which liquefied natural gas flows in a vaporizer for vaporizing liquefied natural gas. The present invention relates to a method for producing a clad tube by a coextrusion method in which the bonding force of the clad tube is improved.

[0002]

2. Description of the Related Art Recently, when coal and petroleum, which are fossil raw materials, are used, natural gas (Natural) which causes less pollution is caused to induce pollution such as acid rain and air pollution.
Gas, NG) is increasing rapidly. An examination of the process of using such natural gas is as follows. First, the gas mined from the gas well is converted into liquefied natural gas (Liquid Natural Gas; LN).
G). The liquefied natural gas is transported to a natural gas terminal using an LNG carrier and stored in a storage tank. The stored LNG is vaporized using a vaporizer, is naturalized again, and is supplied to consumers.

Here, the vaporizer 10 can be schematically shown as shown in FIG. That is, LNG supplied from the lower LNG header tube 16 flows through the inside of the vaporizer tube 14 provided with pins inside, and fresh water or seawater supplied from the seawater pipe 3 flows to the outer surface of the tube 1.
Heat required for vaporization will be supplied into 4. In this way, LNG is vaporized by moving to the upper part of the tube by the external heat, and is naturalized while being discharged through the NG header tube 12.

[0004] Vaporizer tubes 14 used to date
An alloy such as AA3003, which is an aluminum alloy having excellent thermal conductivity and relatively excellent corrosion resistance, is used as a material for the above. However, when seawater is used as a heat source, pitting corrosion (pittin) occurs on the surface of the aluminum alloy.
g) etc. occur at a very high rate,
The life of the vaporizer becomes very short in a few months. Such a short corrosion life not only reduces the operation rate of the vaporizer, but also poses a serious threat to the safety of the vaporizer due to the combustible gas.

[0005] In order to solve such a corrosive problem,
The method currently used is to coat the sacrificial anode metal on the vaporizer tube by thermal spraying to prevent corrosion. That is, A1-
This is a method of protecting the A3003 alloy as a base metal from a corrosive atmosphere by coating an alloy such as 2% Zn on the surface of an aluminum vaporizer to a thickness of about 80 to 400 μm by a thermal spray method. However, the coating thus obtained generally contains many pores and cracks, and if the surface treatment of the base aluminum tube is not suitable, the interface adhesion between the coating and the base is weakened and the coating layer is formed. Peeling occurs. In particular, the pores in the coating layer serve to promote corrosion, and if the interfacial adhesion between the coating layer and the base is low, the sacrificial anode coating layer is peeled off under repeated operating conditions of heating and cooling. The life of the vaporizer is shortened.

[0006]

Accordingly, the present invention has developed a method for forming a material having high corrosion resistance on the surface by using a co-extrusion method capable of removing pores and making the interfacial adhesive strength uniform.

[0007] An object of the present invention is to provide a skin layer (cladding layer) having excellent coating uniformity and a remarkably improved bonding force between a coating layer and a matrix as compared with a tube coated by a conventional thermal spraying method. An object of the present invention is to develop a method for producing an aluminum tube for a vaporizer having a co-extrusion method.

That is, by manufacturing the clad tube by the co-extrusion method, not only the life of the vaporizer tube is improved but also the economical efficiency and safety of the vaporizer.

[0009]

An example of a method of manufacturing a clad tube by a coextrusion method for achieving the object of the present invention includes a step of forming a tube base material, a step of forming a clad material, Putting an extruding material comprising a clad material and the tube base material into a co-extruder,
Heating the extruding material to plastically deform the material; and extruding the clad material on the outer peripheral surface of the tube base material by extruding with a piston pressure of the co-extruder, wherein the tube base material has a plug. When the extruding material is introduced into the co-extruder , the front surface of the plug of the tube base material is formed into a clad.
The plug is fitted into the cladding material so as to be located within the inner diameter of the cladding material.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to a process for producing an aluminum clad tube for a vaporizer by a coextrusion method. A conventional aluminum tube for a vaporizer is manufactured by coating an A1-2% Zn alloy on a base tube by a thermal injection method. Such a coating layer contains not only a large number of pores but also has a tendency to reduce the corrosion resistance of the tube because the thickness is not uniform, the bonding with the base layer is incomplete, and the peeling easily occurs. . Therefore, in order to improve the corrosion resistance of the vaporizer tube, it is necessary to form a coating layer having a fine microstructure, and it is essential to increase the bonding force between the matrix and the coating layer.

Although a tube having such characteristics can be manufactured by a chemical or physical vapor deposition method, a cladding method, etc., the present invention uses a cladding method which is excellent in economy. The cladding method further includes a rolling method, an explosion welding method, an arc welding method, a co-extrusion method, and the like. In the present invention, it is easy to produce a product having a complicated shape, and the mechanical and physical properties of the base metal are reduced. A co-extrusion method with a small effect was used. That is, when extruding an aluminum alloy into a vaporizer tube shape, a co-extrusion method was used in which a sacrificial anode alloy was simultaneously extruded to form a coating layer graded on the surface of the extruded tube. The most important factor in such a coextrusion process is to obtain a uniform thickness of the surface cladding layer over the entire length of the extruded tube.

[0012]

First, as shown in FIG. 2, an extrusion base material is melted using a melting furnace, and a liquid aluminum extrusion tube base material is molded into a mold (not shown) having a diameter of 120 mm and a height of about 255 mm. To produce a cylindrical aluminum billet. A hollow inner diameter portion 23 is formed in such a tube base material 22.

As shown in FIG. 3, the tube base material 22 is placed at the center in a mold 25 having a diameter of about 140 mm, and the clad material 24 to be clad in a 10 mm space between the tube base material 22 and the mold 25 is liquid. Dissolve in the state and then pour.

As a result, as shown in FIGS. 4 and 5, a cylindrical extrusion material in which the tube base material 22 and the clad material 24 are integrated is obtained. The extrusion material thus formed is formed by a coextrusion method.

As shown in FIG. 6, the extruder 20 has a front mold 28 for extruding the material for extrusion into a desired shape.
A container 30 for accommodating the material for extrusion, a piston 32 for pressurizing the material for extrusion, and a tube 32 inserted into the inside diameter portion 23 of the tube base material 22 so that the inside diameter portion is formed in a constant shape during extrusion. And a mandrel 34.
After the container 30 is heated at about 470 ° C. for about 3 hours so as to be plastically deformed, the material for extrusion is transferred to the container 30.
And the extruded material heated at 400 to 450 ° C.
Extrude with a piston 32 pressure of 25 kg / cm ² . At this time, the extrusion speed is 1.2 to 2.0 m / min.

In the vaporizer tube manufactured by this method, the thickness of the clad layer could not be obtained very uniformly.

Therefore, in order to obtain a uniform clad thickness, in the present invention, at the time of extrusion, another clad plate 38 as shown in FIG. 7 was inserted into the end of the extrusion material and extruded. As a result of using such a method, a clad forming tube having a uniform clad thickness in the longitudinal direction and having a shape as shown in FIG. 10 could be manufactured.

Next, a method of simultaneously extruding the clad material so as to be laminated on the outer peripheral surface of the tube base material will be described.

As shown in FIG. 8, when the diameter of the inner diameter portion 43 of the clad material 42 is considerably large, the clad material 42 is located in front of the tube base material 44. The tube base material 44 has an inner diameter portion 47 having a small diameter. Extrusion conditions are almost the same as the previous method.

The pushing force of the piston 32 pushes the tube base material 44 into the inner diameter portion 43 of the glad material 42. In this process, the tube base material 44 is plastically deformed by frictional force.

In the configuration shown in FIG. 8, when the tube base material 44 is pushed into the inner diameter portion 43 of the clad material 42, the thickness of the tube base material 44 is uniform at the inner diameter portion 43.
Absent. In order to prevent this, as shown in FIG. 9, the tube base material 50 is processed into a plug 45 form,
Forming a tube base material 50 having
2 and the material for extrusion consisting of the tube base material 50
Put into an extruder and extrude under the same conditions as in the previous method.
Lad material is laminated on the outer peripheral surface of the tube base material. this
By such a method , a clad tube having a uniform thickness can be manufactured.

The present invention can manufacture a vaporizer tube including a general cladding tube as shown in FIG. 11 and having a radiation fin as shown in FIG. Here, aluminum AA7072, capro nickel (c
For example, AA5052, AA3003, AA6061 and the like can be used as the material of the tube base material. At this time, the thickness of the clad tube can be manufactured from several tens of microns to several millimeters.

[0023]

As described above, according to the present invention,
The corrosion resistance and durability of the LNG vaporizer tube can be significantly improved. In other words, because the microstructure of the cladding layer is dense and the interface bonding strength between the tube base material and the cladding material is more excellent due to diffusion bonding between these metals, the vaporization tube manufactured by the existing thermal spray coating method is used. The extension of the service life is increased in comparison with the above. Also,
Since the manufacturing method of the present invention uses an extrusion method, which is a general method for manufacturing an aluminum alloy, it does not require investment of another apparatus and has excellent productivity. Costs can be greatly reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a conventional LNG vaporizer.

FIG. 2 is a cross-sectional view showing a state where a tube base material is formed according to the present invention.

FIG. 3 is a cross-sectional view illustrating a process in which a tube base material and a clad material are molded by a mold according to the present invention.

FIG. 4 is a cross-sectional view showing a state where a tube base material and a clad material are molded by a mold according to the present invention.

FIG. 5 is a sectional view taken along line AA of FIG. 4;

FIG. 6 is a cross-sectional view illustrating a process of manufacturing an aluminum clad tube for a vaporizer in an extruder according to a first embodiment of the present invention.

FIG. 7 is a cross-sectional view illustrating a manufacturing process of an aluminum clad tube for a vaporizer in an extruder according to a second embodiment of the present invention.

FIG. 8 is a sectional view illustrating a process of manufacturing an aluminum clad tube for a vaporizer in an extruder according to a third embodiment of the present invention.

FIG. 9 is a sectional view illustrating a process of manufacturing an aluminum clad tube for a vaporizer in an extruder according to a fourth embodiment of the present invention.

FIG. 10 is a front sectional view of an aluminum clad tube for a vaporizer discharged from an extruder according to the present invention.

FIG. 11 is a front sectional view of an aluminum clad tube for a vaporizer discharged from an extruder according to the present invention.

[Explanation of symbols]

3 ... seawater pipe, 10 ... vaporizer, 12 ... NG header tube, 14 ... tube, 16 ... LNG header tube,
20: extruder, 22, 44, 50: tube base material, 2
4, 42, 52: clad material, 28: front mold, 30: container, 32: piston, 34: mandrel, 38: clad plate, 45: plug

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Shin Dong-Huk 12-905, Daichi Dong-Sang-Kyun Apartment, Gangnam-gu, Seoul, Korea Republic of Korea Ku Material Apartment (72) Inventor Park Jae-Hong 63-15 Diwadong, Dijeong-gu, Daejeon, Republic of Korea 49-43467 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) B21C 23/00 B21C 23/22

Claims (3)

(57) [Claims] 1. A step of forming a tube preform, a step of forming a clad material, a step of putting an extruding material comprising the clad material and the tube preform into a co-extruder, A step of heating for plastic deformation and a step of extruding the clad material on the outer peripheral surface of the tube base material by extruding with a piston pressure of the co-extruder, wherein the tube base material is formed to have a plug. In addition, when the material for extrusion is put into the co-extruder , the front surface of the plug of the tube base material is
A method for manufacturing a clad tube by a co-extrusion method , wherein the plug is fitted into the clad material so as to be located within an inner diameter portion of the clad material. 2. The front surface of the plug is in front of the cladding material.
The method for producing a clad tube by a coextrusion method according to claim 1, wherein the clad material is receded from an inner surface of the clad material . 3. The co-extruder comprises a mandrel,
Cladding tube with hollow inner diameter by mandrel
The method for producing a clad tube by a coextrusion method according to claim 1, wherein the cladding tube is formed.