JPH0292522A - Manufacture of nonporous tube bundle - Google Patents

Abstract

PURPOSE:To weld uniformly with favourable sealability, by a method wherein after a nonmeltable filler having a high melting point than that of the quality of the material constituting a tube is inserted into an inner circumference of each end part of a plurality of nonporous tubes and the end parts are bundled, a stretching member shrinking at the melting temperature of the tube is wound round a bundle and the circumference of the end part of the tubes each are welded each other under a pressure-contacted state. CONSTITUTION:End parts 10a of a plurality of tubes 10 into which a nonmeltable filler 20 is inserted are bundled and a tapelike stretching member 11 such as one made of PTFE or PFA is wound round the outer circumference. Then the end 10a of the tube 10 is heated at a temperature of at least the melting point of synthetic resin constituting this nonporous tube 10 and not exceeding the melting point of the nonmeltable filler 20. When the same is heated like this, the end parts 10a of the nonporous tubes 10 are welded to one another under a pressure-contacted state by shrinking force of the stretching member 11.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention is directed to bonding the outer periphery of the end of a tube made of a material such as fluororesin, which has excellent mechanical strength, heat resistance, and chemical resistance but is difficult to bond. The present invention relates to a method for manufacturing tube bundles mainly used in heat exchangers and the like.

Technical background of the invention and its problems Conventionally, heat exchange tubes made of metals such as stainless steel, nickel, and copper have been widely used as heat exchange tubes. Although such metal heat exchange tubes have high thermal conductivity and overall heat transfer coefficient, they have problems such as insufficient corrosion resistance against acid solutions and the tendency for scale to adhere to the surface. was there.

In order to solve these problems, heat exchange tubes made of fluororesin have recently been developed. This fluororesin heat exchange tube has excellent heat resistance and chemical resistance, and also has the advantage that scale is difficult to adhere to because the surface is smooth. However, in order to construct a heat exchanger using such fluororesin heat exchange tubes, it is necessary to bundle a large number of fluororesin heat exchange tubes and heat-seal both ends to integrate them. It was difficult to stop all of this.

As shown in Japanese Patent Publication No. 46-4228, a conventional method for manufacturing a fluororesin heat exchange tube bundle by bundling the outer peripheries of the end portions of fluororesin tubes together is as follows:
A large number of fluororesin tubes are aligned, their ends are inserted into a hard sleeve made of polytetrafluoroethylene resin, etc., heated fluid is introduced into the end portions, and then the inside and outside of the heated tubes are heated. A method has been proposed in which a pressure difference is applied to the outer peripheries of the tube ends, thereby deforming the outer peripheries of the tube ends into a honeycomb shape and fusing them together, and also fusing them integrally with the inner surface of the sleeve to form a sealing structure.

However, in this method of manufacturing a tube bundle, there is a possibility that the distribution of the heating fluid may become uneven among the tubes, especially when the tube diameter of each tube is small. There was a problem in that the outer periphery of each tube end became unevenly fused to each other. If the heating of each tube becomes uneven, the viscosity of the tube will drop too much in the overheated part of each tube end, causing the tube to collapse, and the fusion bond will fail in the insufficiently heated part. There was a risk that the sealing properties would be insufficient due to the gap being formed. Therefore, when the tube bundle obtained in this way is used as a heat exchange tube, there is a risk that the fluid flow inside the tube will be poor and the watertightness will not be sufficient, making it impossible to obtain satisfactory heat exchange performance. Ta.

Therefore, in order to eliminate such inconvenience,
As shown in Publication No. 2-21,524, a method for manufacturing a tube bundle has been proposed in which the ends of the bundled tubes are heated from the outer peripheral side with a heater and the ends of the tubes are heated with a heating plate. .

However, in this method of manufacturing a tube bundle, since the heater is used to heat the bundled tubes from the outer circumferential side of the end thereof, a temperature distribution occurs between the outer circumferential side and the center part of the tube bundle. There are still problems in that the outer periphery of each tube end is not uniformly fused to each other, the tube is crushed, and the sealing performance is insufficient.

Purpose of the Invention The present invention aims to solve the problems associated with the prior art as described above. It can be applied even when non-porous tubes such as those made of high quality fluororesin are used, and the outer circumference of the end of the bundled non-porous tube bundle can be uniformly coated without bending or crushing the tubes. Moreover, it is an object of the present invention to provide a method for manufacturing a non-porous tube bundle that can be fused to each other with good sealing properties and is therefore suitable for use in heat exchangers and the like with excellent chemical resistance.

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a non-melting filling made of a material having a melting point higher than the melting point of the material constituting the tubes, on the inner periphery of each end of a plurality of non-porous tubes. After inserting objects and bundling the ends of these tubes, the outer periphery of the ends of the bundled tubes has a melting point higher than the melting point of the material constituting the tubes and shrinks at least at the melting point temperature of the tubes. A stretching member is wound around the tube, and the end portion of the tube around which the stretching member is wound is heated by a heating means to a temperature higher than the melting point of the tube, so that the outer periphery of the end portion of each tube is fused to each other under pressure. It is said that

Preferably, the non-melting filler has a cylindrical shape.

Moreover, it is preferable that the non-melting filler is made of polytetrafluoroethylene. This is because polytetrafluoroethylene has excellent sliding properties and can be easily removed from the inner periphery of the end of the tube after heat fusion.

Further, the stretching member has a tensile strength of 5% or more, preferably 5 to 500%.
It is preferable that the tape be uniaxially stretched at a stretching rate of %.

Furthermore, an outer frame sleeve may be fitted around the outer periphery of the end of the tube heat-sealed by the heating means, and the outer frame sleeve and the tube may be heat-sealed.

According to the method for producing a non-porous tube bundle according to the present invention, a non-melting filler having a melting point higher than the melting point of the tube is inserted in advance into the inner periphery of each end of the non-porous tube, and the non-melting filler is Since a stretched member that heat-shrinks during heat fusion is wound around the outer periphery of the end where the meltable filler is inserted, and then heated, the outer periphery of the end is pressed by the shrinkage force of the stretched member. Furthermore, the ends are not crushed by the non-melting filler and can be thermally fused. In other words, through the process of inserting the non-melting filler, winding and bundling this end with a stretching member, and then heating the end, the process creates a uniform, non-porous, fused structure with good sealability. You can get quality tube bundles.

Therefore, according to the present invention, the outer periphery of the end of a non-porous tube can be reliably and easily integrated without using an adhesive, and can be used in a heat exchanger etc. with excellent chemical resistance. It is possible to provide a non-porous tube with excellent productivity.Furthermore, when the non-porous tube is made of fluororesin such as PFA, the tube has particularly excellent chemical resistance. A bunch is obtained.

DETAILED DESCRIPTION OF THE INVENTION Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

FIG. 1 is a process diagram showing a method for manufacturing a non-porous tube bundle according to an embodiment of the present invention, FIG. 2 is a cross-sectional view showing a method for manufacturing the same non-porous tube bundle, and FIG. 3 is a process diagram showing the same embodiment. 4 is a front view showing the tube end surface of the same embodiment. FIG. 5 is a sectional view of the main part showing the sleeve fusion process of the same embodiment. FIG. 7 is a sectional view showing another embodiment of the invention. Further, FIG. 7 is a front view showing a heat exchange tube using a non-porous tube bundle.

The material of the tubes constituting the non-porous tube bundle manufactured by the method according to the present invention includes conventionally widely used materials such as polyethylene (hereinafter referred to as PE) and polypropylene (hereinafter referred to as PP). ＼Polyolefin resin,
Examples include fluororesin. As this fluororesin,
Polytetrafluorethylene (hereinafter referred to as PTFE),
Copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether (hereinafter referred to as PFA) Copolymer of tetrafluoroethylene and hexafluoropropylene (hereinafter referred to as FEP), Tetrafluoroethylene and hexafluoropropylene A copolymer of perfluorovinyl ether (hereinafter referred to as EPE), a copolymer of ethylene and tetrafluoroethylene (hereinafter referred to as ETFE), etc. are used. Among these materials, when fluororesin is used for the tube, it exhibits particularly excellent chemical resistance and heat resistance.

In the present invention, first, as shown in FIG. 3, a non-melting filler 20 is inserted into the inner periphery of both ends 10a of a plurality of non-porous tubes 10 (inside the non-melting filler shown in FIG. 1). Insertion step 1). The non-melting filler 20 is made of a material having a melting point higher than that of the material constituting the tube 10. Therefore, the material of the non-fusible filler 20 may be a ceramic material such as glass or gypsum, or a metal material, but as described later, the non-fusible filler 20 When removing 20, it is preferable to use the above-mentioned PTFE in consideration of its removability. Powder materials such as sand and salt can also be used.

The shape of the non-melting filler 20 may be a solid cylinder having an outer shape that is approximately equal to or slightly smaller than the inner shape of the tube 10, as shown in FIG. Further, it may have a cylindrical shape having an external shape similar to that of a tube.

Furthermore, when the cross-sectional shape of the tube 10 is an irregular tube shape (referring to a shape other than a circular tube), the external shape of the non-melting filler 20 may be a shape corresponding to its internal shape. preferable.

Further, the insertion length of the non-melting filler 20 is determined according to the heating width for heating the end portion 10a of the tube 10, as shown in FIG. 2, and if this heating width is long, It is preferable that the insertion length of the non-melting filler 20 is increased accordingly, and in some cases, the non-melting filler 20 may be inserted in advance over the entire length of the tube 10.

Next, as shown in FIG.
After focusing step 2) shown in FIG. 1 to focus 0a,
A tape-shaped stretching member 11 that has been previously stretched to a predetermined ratio is wound around the outer periphery of the end portion 10a of the bundled tube 10 (stretching member winding step 3 shown in FIG. 1). The winding width g of this stretched member 11 is determined by the above-mentioned non-melting filler 20.
Similarly, it is determined according to the heating width in the heat fusing step 4 described later, and if this heating width is long, it is preferable that the winding width g of the stretching member 11 is also increased accordingly. Further, the winding thickness of the stretched member 11 is preferably such that the tube does not elute when melted.

The material for the stretched member 11 may be any material as long as it has a melting point higher than the melting point of the material constituting the tube 10 and is highly stretchable. For example, PTFE, PFA, etc. are preferably used. The stretched member 11 is, for example, uniaxially stretched or biaxially stretched, and the stretching ratio is preferably 5% or more, preferably 5 to 500%.

The stretching ratio may be suitably selected depending on the material of the tube 10, its shrinkage rate, adhesiveness, heating conditions, etc. In the heat fusing step 4, the stretching member 11 contracts, and the end portion of the tube 10 It is sufficient if an appropriate pressing force can be applied to 10a.

Next, the tube 1 around which the elongated member 11 is wound in this way
The end portion 10a of the non-porous tube 10 is heated at a temperature higher than the melting point of the synthetic resin constituting the non-porous tube 10 and lower than the melting point of the non-meltable filler 20 (heat fusing step 4 shown in FIG. 1). ). This heating temperature is determined when the material of the stretching member 11 is P.
In the case of TFE, even if PTFE is heated above its melting point, it can maintain its shape, so the temperature may be higher than the melting point of the stretched member 11.
If the material of 1 is PFA, for example, the PFA
It is preferable to heat at a temperature below the melting point of . -Numerically speaking, the heating temperature is equal to or higher than the melting point of the material of the non-porous tube 10 and non-melting, considering thermal deterioration of the tube 10, removability of the non-melting filler 20 and the stretched member 11, etc. It is preferable that the melting point of the material of the elastic filler 20 and the stretched member 11 is lower than the melting point.

Further, as this heating means, there is a means for heating using a heating fluid (Japanese Patent Publication No. 46-4,228), a means for heating the tube bundle 10 from the outer periphery with a heating heater (Japanese Patent Publication No. 60-259,898). For example, the following method may be used.

As shown in FIG. 2, the ends 10a, 10a of the bundle of tubes 10 around which the stretching member 11 is wound are brought into contact with the inner ridges 12a formed at the bottom of the mold 12.12, respectively. Install. Next, both molds 12 and 12 are heated by a heater or the like (not shown) in the state shown in FIG. The heating temperature at this time is
For example, when the material of the tube 10 is ETFE and the material of the elongated member 11 and the non-melting filler 20 is PTFE, the ETF
Since the melting point of E is 270°C, a higher temperature of 280 to 290°C is preferable. This heating temperature is preferably higher than the melting point of the synthetic resin constituting the tube 10 and lower than the melting point of the material constituting the non-fusible filler 20. This is because the filling 20 will eventually be removed from the tube 10. However, this heating temperature
It is also possible to heat the tube 10 and the non-melting filler 20 to a temperature higher than the melting point of the non-melting filler 20 as long as the tube 10 and the non-melting filler 20 are not deteriorated by heating. In some cases, the non-fusible filling 20 is not removed. It goes without saying that the mold 12 may be heated in advance before the tube 10 is installed.

This heating state continues for a predetermined time, and the end 1 of the tube 10
When the end portions 10a of the plurality of tubes 10 are pressed together and fused to each other due to contraction of the stretching member 11 while the tube 0a is heated to a temperature higher than the melting point, the end portions 10a of the tubes 10 are taken out from the mold 12 and the heated tubes 10 are heated. The end portion 10a is cooled. This cooling is performed by natural cooling or forced air cooling by blowing cold air.
This cooling is continued until the temperature drops below the melting point of the material forming the 0.

Such heat fusion is performed at both ends 10a of the tube 10,
10a may be performed at the same time, but one end 10a may be performed at the same time.
It is also possible to cool the end portion 10a after heat-sealing the end portion a, and then heat-seal the other end portion 10a in a similar manner. These selections may be made appropriately depending on, for example, the length of the tube 10, etc. If the length of the tube 10 is long, the heating device will be large, so the latter method,
In other words, a method of heat-sealing the tube 10 one end at a time may be used.

When heated in this way, the end 1 of the non-porous tube 10
0a are pressed together and fused together by the contraction force of the stretching member 11.

In addition, in the present invention, when the non-melting filler 20 has a cylindrical shape, the end portion 10 of each tube 10 does not necessarily have a cylindrical shape.
a There is no need to remove it from the inner circumference.

On the other hand, when a solid-shaped non-melting filler 20 is used, as is clear from the above-mentioned reasons, it is removed after the heat fusing step 4 or after the sleeve fusing step 6. There is a need.

Next, the stretching member 11 wound around the outer periphery of the end portion 10a of the plurality of tube bundles 10 heat-fused in this way is removed (stretching member removal step 5 shown in FIG. 1). The same material as the non-porous tube, or the non-porous tube is PFA or PTFE and the stretched member is PT.
In the case of FE or PFA, it is not necessary to remove the elongated member 11 because they are fused together. This is because the elongated member 11 can become an outer frame sleeve 14, which will be described later.

Thereafter, the outer frame sleeve 14 is inserted into the outer periphery of the end 10a of the tube 10 that has been integrated by the elongated member 11, and is heat fused (sleeve fusion step 6 shown in FIG. 1).
). This state is shown in FIG. This outer frame sleeve 14 is formed to have an outer diameter that is approximately the same as or larger than the outer circumferential portion of the main body of the tube 10 that is bundled together, and is made of a material that is fused to the tube 1o when heated. Preferably. For example, when the tube 10 is made of PP resin or PE resin, the outer frame sleeve 14 is preferably made of PP resin or PE resin, respectively.
, ETFE.

When made of fluororesin such as PTF E, the outer frame sleeve 14 is also made of PFA.

It is preferably made of fluororesin such as FEPSETFE or PTFE.

The tube 1° into which the outer frame sleeve 14 is inserted is heated by a conventionally known heating means (for example, the heating method disclosed in Japanese Patent Publication No. 46-4.228) as described in the explanation of the heat fusion step 4. Heating methods using fluids and JP-A-60-
The heating method using a heater disclosed in Japanese Patent No. 259,898 can also be used, but for example, the following method can also be used.

That is, as in the heat-sealing process 4, as shown in FIG. It is installed so as to be in contact with the inner protrusion 12a. Next, in the state shown in FIG. 5, both the molds 12,
1. Heat 2. The heating temperature at this time is
For example, the material of the tube 10 and the outer frame sleeve 14 is determined by the material of the tube 10 and the outer frame sleeve 14.
'E', and when performing this sleeve fusion step without removing the non-melting filler 20, the material of the non-melting filler is PTFE, and if the material is PTFE, ETFE is used.
Since the melting point of is 270°C, a higher temperature of 280 to 290°C is preferable. This heating temperature is preferably higher than the melting point of the synthetic resin constituting the tube 10 and lower than the melting point of the material constituting the non-fusible filler 20. Filling 2
0 is based on the reason that it will eventually be removed from the tube 10. However, this heating temperature is limited to a range in which the tube 10 does not deteriorate due to heating.
It is also possible to heat the tube to a temperature higher than the melting point of 0, and in this case, the tube 10 and the non-melting filler 20 are heat-fused, so the non-melting filler 20 is not removed. Note that, of course, the mold 12 may be heated in advance before the tube bundle 10 is installed.

The tube bundle 10 that has completed the sleeve fusion step 6 in this manner is taken out from the mold 12, and its heated both ends 10a are cooled. This cooling may be performed by natural cooling or forced cooling, as in the heating and fusing step 4, and the cooling is performed until the temperature drops below the melting point of the materials forming the tube 10 and the outer frame sleeve 14.

According to the tube bundle manufacturing method according to the embodiment of the present invention, the ends 10a of the plurality of non-porous tubes 10
A non-melting filler 2 made of a material having a melting point higher than the melting point of the material constituting the tube 10 on the inner periphery.
0 respectively, and the ends 10a of these tubes 10
After bundling, the end 10 of the bundled tube 10
a.A stretched member 11 having a melting point higher than the melting point of the material constituting the tube 10 and shrinking at least at the melting point temperature of the tube 10 is wound around the outer periphery, and the end of the tube 10 around which the stretched member 11 is wound. Since the portion 10a is heated by the mold 12 provided with a heating means, the end portion 10a of the tube 10 is not bent during this heat fusion, and the tubes 10 are pressed together by the contraction force of the stretching member 11. This will result in fusion.

Furthermore, in this embodiment, the stretching member 11 is removed and, after this, the end portion 10 of the tube bundle 10 that has been unified by the contraction force of the stretching member 11 is removed.
Since the outer frame sleeve 14 is fitted onto the tube a and heat fused using the mold 12, each tube 10 is fused to the outer frame sleeve 1-4 under pressure.

Therefore, according to this embodiment, the outer peripheries of the ends of each tube can be reliably integrated without using adhesives and with the minimum number of steps, resulting in a heat exchanger with excellent chemical resistance. A non-porous tube bundle that can be suitably used can be obtained. In particular, when the non-porous tube is made of fluororesin, it has excellent chemical resistance.

Note that the present invention is not limited to the one embodiment described above, and can be modified in various ways.

For example, as shown in FIG. 6, a non-melting filler 20 made of a material having a melting point higher than the melting point of the material constituting the tubes 10 is placed on the inner periphery of the end portion 10a of a plurality of non-porous tubes 10. (insertion step of inserting a non-melting filler), and converging the tubes 10 so that the ends 10a of the tubes 10 are aligned (convergence step), and wrapping the outer frame sleeve 14 around the outer periphery of the converged ends 10a. Later, the stretched member 1 is further wound around the outer frame sleeve 14 (stretched member and outer frame sleeve winding step), and the end portion 10a of the tube 10 is heated and fused (heat fusion step). You can do it like this.

As the outer frame sleeve, a sleeve formed by winding a sheet may be used. At this time, the outer frame sleeve 14, the tube 10, the elongated member 11, and the non-melting filler 20 can be made of the same materials as in the first embodiment, and the heating process in this embodiment can be The heating means and heating conditions can also be carried out under the same conditions as in the first embodiment. However, it is preferable that the outer frame sleeve 14 and the tube 10 are made of the same material. This is because the outer frame sleeve 14 and the tube 10 need to be fused together.

Even in this case, when the end portion 10a of the tube 10 is heated in the heat fusion process, the stretching member 1 wound around the outermost circumference of the end portion 10a of the tube 10 is heated.
Due to the contraction force of 1, the end portion 10a of the tube 10 and the outer frame sleeve 14 wound around the outer periphery of the tube 10 are simultaneously pressed and contracted in diameter, and are fused to each other. 1- Therefore, this embodiment has an advantage over the first embodiment in that the sleeve fusing step 6 can be omitted.

Further, in each of the above-described embodiments, both ends of straight tubes are bundled and heat-fused, but the present invention is not limited to this, and the ends of bent tubes are bundled and heated. It is also within the scope of the present invention to fuse.

Furthermore, in this case, it is also within the scope of the present invention to bundle one end of the tube into a bundle and bundle the other end into two or more.

The non-porous tube bundle 10 collected in this way is
It is used as a heat exchange tube as shown in FIG. In addition, in FIG. 7, 14 is an outer frame sleeve.

As described in detail, according to the present invention, a non-melting filling made of a material having a melting point higher than the melting point of the material constituting the tubes is provided on the inner periphery of the end portion of a plurality of non-porous tubes. After inserting objects and bundling the ends of these tubes, the outer periphery of the ends of the bundled tubes has a melting point higher than the melting point of the material constituting the tubes and shrinks at least at the melting point temperature of the tubes. Winding the stretching member, heating the end of the tube around which the stretching member is wound by a heating means to a temperature higher than the melting point of the tube, and melting the outer periphery of the end of each tube to each other under pressure, and then Since the stretching member is removed, the ends of the tube bundle can be easily fused uniformly, with good sealing properties, and without using adhesive and without bending or soaking the ends of the tubes. It has this excellent effect. As a result, if such a non-porous tube bundle is applied to a heat exchanger, it will have chemical resistance, heat resistance, corrosion resistance,
A heat exchange tube with excellent sealing properties can be obtained.

[Brief explanation of drawings]

FIG. 1 is a process diagram showing a method for manufacturing a non-porous tube bundle according to an embodiment of the present invention, FIG. 2 is a cross-sectional view showing a method for manufacturing the same non-porous tube bundle, and FIG. 3 is a process diagram showing the same embodiment. 4 is a front view showing the tube end of the same embodiment, FIG. 5 is a sectional view of the main part showing the sleeve fusion process of the same embodiment, and FIG. A sectional view showing another embodiment of the present invention, and FIG. 7 is a front view showing a heat exchange tube using a general non-porous tube bundle. 1... Non-melting filler interpolation process, 2... Focusing process,
3... Stretched member winding process, 4... Heat fusion process, 5
...Stretched member removal step, 10...Non-porous tube,
10a... End portion, 11... Stretching member, 12... Mold (heating means), 20... Non-melting filler.

Claims (6)

[Claims] (1) A non-melting filler made of a material having a melting point higher than the melting point of the material constituting the tubes is inserted into the inner periphery of each end of a plurality of non-porous tubes, and the ends of these tubes are After bundling, a stretched member having a melting point higher than the melting point of the material constituting the tube and shrinking at least at the melting point temperature of the tube is wound around the outer periphery of the end of the bundled tube, and this stretched member is wound. A method for manufacturing a non-porous tube bundle, characterized in that the end portions of the tubes are heated to a temperature higher than the melting point of the tubes by a heating means, and the outer peripheries of the end portions of the respective tubes are fused to each other under pressure. (2) The method for manufacturing a porous tube bundle according to claim 1, wherein the non-melting filler has a cylindrical shape. (3) The method for manufacturing a non-porous tube bundle according to claim 1 or 2, wherein the non-melting filler is made of polytetrafluoroethylene. (4) The method for manufacturing a non-porous tube bundle according to any one of claims 1 to 3, wherein the tube is made of fluororesin. (5) Manufacturing a non-porous tube bundle according to any one of claims 1 to 4, wherein the stretching member is a stretched tape uniaxially stretched at a stretching rate of 5% or more. Method. (6) A claim characterized in that an outer frame sleeve is fitted around the outer periphery of the end of the tube bundle heat-fused by the heating means, and the outer frame sleeve and the tube bundle are further heat-fused. The method for producing a non-porous tube bundle according to any one of Items 1 to 5.