KR100665322B1 - Bellows Type PTFE Expansion Joint and Process - Google Patents

Abstract

The bellows type PTFE expansion pipe 100 according to the present invention is an inner tube having a uniform thickness in a expansion pipe made of a bellows composed of a plurality of peaks 1 and a valley 2 and flare 3 at both ends thereof. (11) and the outer tube is characterized by consisting of two. It is preferable that the thickness of the outer tube is as thin as 50 to 80% of the thickness of the inner tube. For example, when the thickness of the inner tube is 3 mm, the thickness of the outer tube is preferably 2 mm. The inner tube 11 and the outer tube 12 are in close contact with each other, that is, at the position of the acid 1 of the outer tube 12 to discharge the air existing therebetween when injecting compressed air during molding. Air discharge holes (not shown) may be formed one by one.

Bellows-Type PTFE Expansion Joint, Inner Tube, Outer Tube

Description

Bellows Type PTFE Expansion Joint and Process

1 is a partially cut perspective view for showing the cross-sectional thickness of a conventional bellows type PTFE (polytetrafluoroethylene) expansion joint.

2 is a schematic perspective view for showing the inside of a mold for forming a bellows type PTFE expansion pipe.

3 is a partial cutaway perspective view of one embodiment of a bellows-type PTFE expansion joint according to the present invention.

4 is a partial cutaway perspective view of one embodiment of a bellows type PTFE expansion pipe with a T-ring and an inner ring (vacuum ring vacuum ring) according to the present invention.

5 is a schematic perspective view of a set of expansion joints in which one embodiment of the bellows-type PTFE expansion joint according to the present invention is assembled by a pair of flanges at both ends.

6 is a schematic perspective view of a T-ring assembled to the outside of a bellows-type PTFE expansion pipe according to the present invention.

7 is a schematic perspective view of an inner ring assembled inside the bellows-type PTFE expansion pipe according to the present invention.

* Brief description of the major symbols in the drawings *

1: mountain 2: goal

3 flare 11 inner tube

12: outer tube 20: T-ring (outer ring)

30: Vacuum ring 100: PTFE expansion joint pipe

200: flange

Field of invention

The present invention relates to a bellows type expansion joint. More specifically, the present invention relates to a method for manufacturing a bellows type PTFE expansion pipe manufactured by using PTFE resin as a raw material and used in piping equipment of various process engineering.

Background of the Invention

Bellows-type expansion joints are used for pipe-work or flue-gas pipes of various process engineering. In various engineering pipes, expansion or mechanical vibration occurs due to heat or pressure, and a bellows type expansion pipe is widely applied for the purpose of absorbing such thermal expansion and vibration.

For example, bellows type expansion pipes are being applied to many fields such as power plants, petrochemicals, refrigeration, metallurgy, nuclear power, air conditioning systems, aviation, construction, automobiles, water treatment and incinerators.

The bellows type expansion pipe is made of PTFE resin as a raw material, and a method of manufacturing the same is well known by those skilled in the art. Briefly describing a conventional method for manufacturing a bellows type PTFE expansion pipe, a seamless tube is made from a PTFE resin powder, and the surface of the manufactured seamless tube is made to be uniform in thickness by lathe processing. A seamless tube is produced, the shelf-free tube is inserted into a mold, and the mold is sufficiently heated in an electric furnace at about 360 ° C., and then compressed air is injected into the mold, that is, inside the tube, thereby expanding the bellows-type PTFE. Produce a sound tube.

FIG. 1 is a partially cut perspective view for showing the cross-sectional thickness of a conventional bellows type PTFE expansion pipe, and FIG. 2 is a schematic perspective view showing the inside of a mold for forming the same.

PTFE expansion pipe produced by the conventional method is not uniform in the thickness of the cross section as shown in FIG. The most important technique for PTFE expansion joints is that their thickness must be uniform. It is necessary to maintain the uniform thickness of the expansion joint so that it is uniformly pressured, and thus can withstand high temperatures and high pressures. If the expansion joint is not uniform in thickness and there is a thin part, the part becomes vulnerable and will eventually burst. The contents flowing inside the pipe are often high temperature and high pressure, especially poisonous substances such as sulfuric acid and hydrochloric acid.In the event of an explosion of the bellows PTFE expansion pipe in such piping equipment, it is fatal to not only factory facilities but also human accidents Will result. Therefore, developing a completely safe bellows type PTFE expansion pipe considering the worst condition such as high temperature and high pressure poison is one of the important tasks in this field.

The bellows type PTFE expansion pipe is manufactured in bellows shape by the mold as shown in FIG. 2, and the conventional bellows type PTFE expansion pipe is thin in the vicinity of the bone 2 as shown in FIG. Losing symptoms appear.

The bellows type PTFE expansion pipe has a flare 3 integrally formed at both sides thereof so that a flange can be inserted therein, and a plurality of peaks 1 and valleys 2 are formed therein to form a bellows shape. Achieve. A cylindrical PTFE tube is inserted into the mold, and compressed air is injected into the tube while the mold and the PTFE tube are sufficiently heated in an electric furnace. At this time, the outer surface of the tube is in contact with the hill 1 'of the mold, and then in contact with the valley 2' of the mold, so that the hill 1 and the valley 2 are formed, respectively.

Since the outer surface of the cylindrical PTFE tube first contacts the acid 1 'of the mold, the valley 2 portion becomes thinner as shown in FIG. When the thickness of the valley 2 portion becomes thin, the portion becomes vulnerable to high temperature and high pressure, and the likelihood of bursting increases.

The present inventors are made of two-layer PTFE tube to solve the drawbacks of the conventional bellows type PTFE expansion pipe as described above to develop a completely safe expansion pipe of the present invention without fear of bursting under the worst conditions It is early.

It is an object of the present invention to provide a two-ply bellows-type PTFE expansion joint which does not break even under the worst high temperature and high pressure conditions.

Another object of the present invention to provide a bellows-type PTFE expansion pipe made of an inner tube and an outer tube, the expansion joint tube can be maintained uniform thickness of the inner tube.

It is still another object of the present invention to provide a two-ply bellows type PTFE expansion pipe having an outer ring (T-ring) to prevent expansion of the expansion pipe in case of high pressure applied inside the pipe. will be.

It is still another object of the present invention to provide a double-ply bellows type PTFE expansion pipe having an inner ring for preventing the expansion pipe from crushing when high pressure is applied from the outside of the pipe.

It is still another object of the present invention to provide a double-ply bellows type PTFE expansion pipe that can prevent the bellows squirm phenomenon.

The above and other objects of the present invention can be achieved by the present invention described below.

Summary of the Invention

The bellows type PTFE expansion pipe 100 according to the present invention is an inner tube having a uniform thickness in a expansion pipe made of a bellows composed of a plurality of peaks 1 and a valley 2 and flare 3 at both ends thereof. (11) and the outer tube is characterized by consisting of two.

It is preferable that the thickness of the outer tube is as thin as 50 to 80% of the thickness of the inner tube. For example, when the thickness of the inner tube is 3 mm, the thickness of the outer tube is preferably 2 mm.

The inner tube 11 and the outer tube 12 are in close contact with each other, that is, at the position of the acid 1 of the outer tube 12 to discharge the air existing therebetween when injecting compressed air during molding. Air discharge holes (not shown) may be formed one by one.

When high pressure is applied to the inside of the pipe, the T-shaped outer ring (T-ring) 20 may be fixed to be inserted into the bellows, respectively, to prevent expansion of the expansion pipe. The outer ring 20 is made of steel, and welds two members as shown in FIG.

When high pressure is applied from outside the pipe, an inner ring 30 (called a vacuum ring) 30 may be inserted into the bellows, respectively, to prevent the expansion pipe from crushing inward. As shown in Fig. 7, the inner ring should be coated with a stainless steel elastic member with a resin such as PTFE material to prevent the stainless steel from being corroded by the contents flowing therein.

The bellows type PTFE expansion pipe according to the present invention inserts the inner tube made of PTFE resin into the outer tube to be in close contact with the outer tube, inserts the assembled inner tube and the outer tube into the mold, and seals the mold. Is sufficiently heated in an electric furnace at about 360 ° C., and compressed air is injected into the heated mold.

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

Detailed Description of the Invention

1 is a partial cutaway perspective view for showing the cross-sectional thickness of a conventional bellows-type PTFE (polytetrafluoroethylene) expansion pipe, Figure 2 is a schematic perspective view for showing the inside of the mold for forming the bellows-type PTFE expansion pipe . The method of manufacturing a conventional bellows-type PTFE expansion pipe as shown in FIG. 1 with the mold shown in FIG. 2 can be easily carried out by those skilled in the art. . Of course, the mold shown in FIG. 2 only shows the body half to show its interior, and a side member (not shown) which seals a pair of the mold and its left and right sides is further needed. This can also be easily carried out by those skilled in the art to which the present invention pertains.

The bellows type PTFE expansion pipe has a flare 3 integrally formed at both sides thereof so that a flange can be inserted therein, and a plurality of peaks 1 and valleys 2 are formed therein to form a bellows shape. Achieve. However, the conventional bellows-type PTFE expansion pipe becomes thinner in the vicinity of the valley 2 as shown in FIG. 1 and maintains the original thickness in the vicinity of the mountain 1. When the thickness of the valley 2 portion becomes thin, the portion becomes vulnerable to high temperature and high pressure, and the likelihood of bursting increases.

As such, the conventional bellows type PTFE expansion pipe becomes thinner in the vicinity of the valleys 2, so that when the seamless PTFE tube inserted into the mold is heated inside the mold and compressed air is injected, the outer surface of the tube This occurs because the outer surface of the tube contacts the valleys 2 'of the mold after first contacting the mold 1' of the mold. In other words, since the outer surface of the tube first contacts the acid 1 'of the mold, the valley 2 portion becomes thinner as shown in FIG.

In the present invention, by developing a double-layered PTFE tube to solve the drawbacks of the conventional bellows-type PTFE expansion joints as described above to develop a completely safe expansion joint of the present invention without fear of bursting even under the worst conditions It is early.

3 is a partially cut perspective view of one embodiment of a bellows-type PTFE expansion pipe made of a two-ply tube according to the present invention. The bellows of the present invention consists of two layers of inner tube 11 and outer tube 12, which is manufactured by inserting an inner tube into an outer tube and then putting a pair of overlapping tubes into a mold. In the bellows of the present invention thus prepared, the thickness of the outer tube is not uniform as in the conventional bellows, but the thickness of the inner tube is almost uniform. This is because when the bellows is molded, the outer tube first contacts the mold 1 'and then the valley 2', and the inner tube does not directly contact the mold surface.

In the bellows-type PTFE expansion pipe made of two-ply tubes according to the present invention, it is not very important that the thickness of the outer tube is not uniform. However, if the thickness of the inner tube is kept uniform, sufficient objects can be achieved. Indeed, as in the present invention, in a bellows-type PTFE expansion pipe made of a two-ply tube, the inner tube is subjected to all pressure, and the outer tube is relatively very small. Therefore, it is not important that the outer tube is not uniform in thickness. Of course, it would be more desirable if the thickness of the outer tube is kept uniform, but this is almost impossible in the molding of the bellows.

The inner tube and the outer tube may be the same thickness, but the outer tube is preferably thinner than the inner tube because of the role of the outer tube as described above. In this way, the raw material of PTFE can be further saved. At this time, the thickness of the outer tube 12 is formed as thin as 50 ~ 80% of the thickness of the inner tube 11, as shown in the enlarged main portion of FIG. For example, when the thickness of the inner tube is 3mm, the thickness of the outer tube is preferably 2mm. As the bellows increases in size, the thickness can be adjusted accordingly. This can be easily carried out by those skilled in the art.

Bellows-type PTFE expansion pipe made of a two-ply tube according to the present invention is not completely melt-tight contact between the inner tube and the outer tube, there is a gap therebetween. In other words, there is air between the inner tube and the outer tube, which expands when the compressed air is injected into the tube during the bellows forming, increasing the distance between the inner tube and the outer tube, thereby making the product less tight. Will be produced. Therefore, in order to discharge the air existing between the inner tube and the outer tube to the outside, it is preferable to form at least one air discharge hole (not shown) in the acid (1) position of the outer tube (12). The size of this air discharge hole depends on the size of the bellows, which can be easily implemented by those skilled in the art. Usually, a hole having a diameter of about 1 to 3 mm is preferable, but is not necessarily limited thereto.

FIG. 4 shows a partially cutaway perspective view of one embodiment of a bellows-type PTFE expansion pipe with a T-ring and an inner ring, the T-ring on the outside of which is intended to reinforce the bearing capacity of the bellows. And insert the inner ring.

6 is a schematic perspective view of a T-ring assembled to the outside of a bellows-type PTFE expansion pipe according to the present invention, the same metal member being the outer ring (T-ring) 20 whose cross section is T-shaped; The two are brought into contact with each other, inserted into the outside of the bellows, and joined by welding. The T-ring is made of steel and is further provided with this T-ring (outer ring) for the purpose of preventing the expansion joint pipe from expanding when high pressure is applied to the inside of the pipe. The method of welding two outer rings (T-rings) 20 by abutting each other to the outside of the bellows can be easily carried out by those skilled in the art.

7 is a schematic perspective view of the inner ring 30 assembled inside the bellows-type PTFE expansion pipe according to the present invention. The inner ring is further provided to prevent the expansion joint pipe from crushing when high pressure is applied from the outside of the pipe. The inner ring 30 is formed of an O-ring shape in which one side of the stainless steel elastic member 31 is opened, and a resin such as PTFE material on the outer surface of the inner ring 30 to prevent corrosion of the elastic member 31. ) Is applied. The elastic member 31 must be completely sealed with a resin, because the contents flowing therein must be prevented from being corroded by the contents when the contents are poisons such as hydrochloric acid or sulfuric acid.

Bellows-type PTFE expansion pipe of the present invention is made of a two-ply PTFE tube, because it is reinforced by the outer ring and the inner ring as described above can prevent the squirm phenomenon that the bellows is twisted or crushed.

5 is a schematic perspective view of a set of expansion joints in which one embodiment of a bellows-type PTFE expansion joint according to the present invention is assembled by a pair of flanges 200 at both ends. The method of assembling the flanges on both ends of the PTFE bellows is the same as the method of assembling the bellows joint pipe joint in the related art.

Two-ply bellows-type PTFE expansion pipe according to the present invention is produced by the following method.

First, PFTE cylindrical tubes having different diameters are manufactured so that the inner tube made of PTFE resin is inserted into the outer tube to be in close contact with the inner tube. It is manufactured by a conventional method. However, at this time, the thickness of the outer tube 12 is preferably about 50 to 80% thinner than the thickness of the inner tube 11.

The two-ply assembled PTFE tube is inserted into a mold, and the sealed mold is sufficiently heated in an electric furnace at about 360 ° C., and compressed air is injected into the heated mold, that is, the tube. This is exactly the same as the conventional bellows manufacturing method.

Of course, after manufacturing the two-ply bellows-type PTFE expansion pipe as described above, the outer tube may be cut to use only the inner tube having a uniform thickness. However, since a lot of manpower is required to cut the outer tube and there is a risk of damaging the inner tube at the time of cutting, in most cases, it is preferable to use the outer tube without cutting it and removing it.

The present invention is a bellows type PTFE expansion joint consisting of an inner tube and an outer tube, because the thickness of the inner tube can be kept uniform, there is no risk of bursting even under the worst high temperature, high pressure conditions, high pressure inside the pipe In addition, an outer ring (T-ring) is further provided to prevent expansion of the expansion pipe in case of being caught, and an inner ring is further provided to prevent the expansion pipe from crushing when high pressure is applied from outside the pipe. The present invention has an effect to provide a method for manufacturing a bellows type PTFE expansion pipe which can prevent a sq-urim phenomenon of the bellows.

Simple modifications and variations of the present invention can be readily used by those skilled in the art, and all such variations or modifications can be considered to be included within the scope of the present invention.

Claims (8)

delete delete delete delete delete Manufacturing an outer tube from a PTFE resin; Manufacturing an inner tube from a PTFE resin; Inserting the inner tube made of PTFE resin into close contact with the outer tube made of PTFE resin; Inserting the inner and outer tubes of the PTFE resin assembled in two layers into a mold; Fully heating the outer tube in the sealed mold and the PTFE resin at the same time in an electric furnace at 360 ° C .; And injecting compressed air into the heated PTFE resin inner tube; A step of contacting and joining two metal outer rings of a T-shape by contacting each other to the bone of the PTFE expansion pipe formed with the acid and the valley formed by the compression process; Method for producing a bellows-type PTFE expansion joint characterized in that consisting of. The method of manufacturing a bellows-type PTFE expansion joint according to claim 6, wherein the outer tube (12) has a thickness of about 50 to 80% of the inner tube (11). delete

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