JPS59106786A - Method of fixing outer layer pipe and inner pipe for coating - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] This invention relates to a fixing method between both tubes to prevent the problem.

Modern high-rise buildings such as residential and office buildings are equipped with fire prevention measures, but these drain pipes, drain pipe ventilation pipes, and power distribution pipes penetrate vertically and horizontally into each compartment of these buildings. In addition to metal and ceramic materials, water supply pipes and air supply/exhaust ducts are also made of synthetic resin pipes such as polyvinyl chloride due to their ease of handling, durability, workability, and sound deadening properties. The outer surface is often coated with a coating made primarily of cement to impart fire resistance. However, metal or ceramic materials may also be coated to provide dew resistance, impact resistance, and the like.

However, in the above case, taking the synthetic resin inner tube as an example, even if a fire-resistant, for example, inorganic coating is applied to the outer periphery, the synthetic resin inner tube usually has a higher coefficient of thermal expansion than the coating and outer tube. Because of the large
Since the outer tube often breaks due to thermal expansion of the inner tube, measures are usually taken to prevent this by providing a desired gap between the inner and outer tubes.

By the way, the easiest way to create this gap is to manufacture both the inner and outer tubes with the desired diameter and insert the inner tube into the outer tube, but it is not possible to fix the positional relationship between the inner and outer tubes. Otherwise, during piping construction, there will be problems in integrating the inner and outer pipes and supporting the load with a hanging band, etc., or there will be problems in handling, such as ease of detachment during transportation or inventory. As a countermeasure against this, various methods for preventing withdrawal have been proposed. For example, methods are known in which a plurality of strings are interposed in the length direction in the gap between the inner and outer tubes, a foamable resin is injected into the edge of the gap to cause foaming, and a wedge is driven into the gap. .

However, in the case of the foamable resin, it is narrow, for example, 0.3 m.
It is practically difficult to effectively and efficiently inject into a gap of about 1.5 m, and in the case of the wedge, there is a risk of damage to the end of the outer tube when driving the wedge, as well as the diameter of the inner and outer tubes and the weight of the outer tube. However, the method of inserting various strings into the gap requires inserting the inner tube and the string into the outer tube at the same time. Moreover, it is not practical because it has to be inserted with a certain degree of firmness, leading to damage to the outer tube, and the method itself is complicated, making it difficult to mass-produce.

The inventors of the present invention have conducted extensive studies on fixing methods between the inner and outer tubes, which have not been found to be sufficient with these conventional methods. The present invention has been completed based on the discovery that the above-mentioned conventional problems can be solved without leaving any problems behind by heat-shrinking and tightly wrapping the product with a film.

That is, the gist of the present invention is to provide a method for inserting an inner tube into an outer tube for coating, exposing both ends of the inner tube, and fixing the inner tube at least one of the exposed portions of the inner tube. The method of fixing the outer layer tube and the inner tube includes surrounding a portion near the end of the outer layer tube with a heat-shrinkable film, and heat-shrinking the film to bring it into close contact with the outer peripheral surface of the inner tube.

Hereinafter, the present invention will be explained using the drawings.

FIG. 1 shows a partially cutaway side view of a state in which an inner tube 2 longer than the outer covering tube 1 is inserted.

The gap 3 between the two tubes is usually about 0.01 to 1.0 +++ mli], and a desired gap is selected in consideration of the coefficient of thermal expansion depending on the materials and diameters of the inner and outer tubes.

FIG. 2a is a side view of the case where the heat-shrinkable tubular film 4 is placed so as to surround the outer periphery of the inner tube 2' near both ends of the outer covering tube 1, respectively.

The length of the heat-shrinkable film 4 is selected so that it can be tightly attached to the inner tube 2 by a desired length when it is shrunk by heat treatment in the next step, but this depends on the heat-shrinkage rate of the heat-shrinkable film. Of course.

The length of the portion in close contact with the inner tube, the thickness of the heat-shrinkable film used, the inner tube surrounding diameter, etc. are often selected empirically in consideration of the load due to the weight of the first outer coating layer, etc.

In other words, it must be able to withstand the long-term impact force caused by the detachability of the outer tube when the inner tube is inserted into the outer tube for transportation or when it is placed against the outer tube during storage. The strength of the film after shrinkage and the degree of adhesion to the inner tube are important selection factors. In addition, when the exposed part of the inner tube is fitted into the joint tube and the two outer tubes are butted together, the shrinked film may be buried, so the length and thickness of the shrinked film also depend on these factors. Become.

FIG. 2b is a view taken along the line ■-■ in FIG. 2a, and shows the inner tube 2,
Outer tube for covering 11 Gap 3 therebetween and heat-shrinkable film 4
This conceptually shows the mutual positional relationship.

The heat-shrinkable film having the tubular legs is most convenient to use, but the present invention is not limited thereto. A method of wrapping a sheet-like material around the desired location and securing the ends with adhesive or heat sealing may also be used.

The heat-shrinkable film used in the present invention may be one used for so-called shrink wrapping, and generally a stretch-molded synthetic resin film or sheet is suitable. As the material, polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, hydrochloric acid rubber, polyester, polyamide, etc. are used as appropriate.

FIG. 3 shows a side view of the heat-shrinkable film 4 in FIG. λ, with the covering outer layer tube side folded back to the outside to form a double layer film 4a.

FIG. 4 is a side view of a case in which a ring-shaped string 5 is attached to the outer surface of the inner tube 2' near the end of the outer covering tube before the heat-shrinkable film 4 is inserted in FIG. 2a. show.

Figure 5 is a side view of the heat-shrinkable film in the state shown in Figure 2a when it is heated and shrunk.
Due to the increased thickness and close contact with the inner tube, the outer covering tube will not come off to the left or right.

However, depending on how the combined inner and outer tubes are handled, the heat-shrinkable film may only be attached to one side. For example, if you want to store it upright, you only need to store it at the bottom.

Figure 6 is a side view of the heat-shrinkable film in the state shown in Figure 3 when it is heated and shrunk, showing that the shrinked film 4' has a larger thickened part 4'', and the shrink film is attached to the inner tube. Because the double layer film 4a is in close contact with the inner tube and the folded double layer film 4a easily comes into contact with the inner tube, when the film contracts, it shrinks and moves toward the outer coating tube, resulting in 1. Shrinkage. The film 4'
It is located closer to the outer coating tube side than in the case of the figure, and the displacement of the outer layer tube with respect to the inner tube is further reduced, which is more effective in achieving the object of the present invention.

Note that this effect can be similarly obtained even if the film is folded inward. Furthermore, it goes without saying that it may be folded back into multiple layers.

FIG. 7 is a side view of the heat-shrinkable film 4 shown in FIG. 4 after being heated and contracted. is formed near the outer coating tube, and the effect is similar to or better than that shown in FIG. 6.

The ring-shaped string shown in Figures 4 and 7 is for creating a bulge in the shrink film 4', so there is no particular restriction as long as it has this function, and in addition to endless strings such as rubber bands, metal It may also be wrapped around a fiber string.

Note that the heat-shrinkable film is removed during piping construction, but for the convenience of removal, one or more perforations (small hole chain) are inserted into the heat-shrinkable film in the length direction of the inner and outer tubes or in a direction close to it. ) is sometimes used.

Since the present invention has the above-described configuration, the intended purpose of fixing the inner and outer tubes can be fully achieved.

Example 1 A rigid polyvinyl chloride pipe with an inner diameter of 114.6 mm and an outer diameter of 13
Insert the cement mortar outer layer tube with a length of 2.000 mrn, close to both ends of the outer layer tube, and make the inner tube with a diameter of 117 m, a thickness of 30 microns, and a length of 90 m.
extrapolate a heat-shrinkable tubular polyvinyl chloride film of m,
As a result of applying hot air at about 100° C., a state as shown in FIG. 5 was formed in close contact with the inner tube surface. The thickness of the shrunk film was about 1 mm, and the gap between the film and the outer tube was about 2 mm.

The fixed inner and outer tubes thus obtained are 20 to 30
It withstood being stored for two months at ℃ and transported 500 km on a horizontal truck, and no separation of the pipes was observed.

Example 2 A test was carried out under the same conditions as in Example 1 except that the heat-shrinkable film in Example 1 was used by folding the outer covering tube side 1/3 (30 mm) outward and using it in the state shown in Figure 3. We looked at the effect, but found that the maximum thickness of the shrunk film was about 2 mm, the gap between the film and the end of the outer layer tube was about 1 mm, and the displacement of the outer layer tube during storage and transportation. Almost the same effects as in Example 1 were obtained, except that there was less and more stable results.

Example 3 Before inserting the heat-shrinkable film in Example 1, a rubber ring with a diameter of 1 m 1 rL was inserted and attached to the outer surface of the inner tube in advance close to the end of the outer layer tube, so that it was in the state shown in Figure 4. The experiment was carried out under the same conditions as in Example 1 except that the thickness of the rubber ring and the shrunk film were approximately 2 mm at maximum, and the gap between the film and the end of the outer layer was approximately 2 mm. 11n7
Almost the same effect as in Example 1 was obtained, except that the outer layer tube had little displacement during storage and transportation and was stable.

[Brief explanation of drawings]

Figure 1 is a partially cutaway side view of the inner tube inserted into the outer layer tube for coating, Figure 2a is a side view of the inner tube covered with a heat shrink film, and Figure 2b is Figure 2a. Fig. 3 is a side view of the heat-shrinkable film with one end folded back, and Fig. 4 shows a ring-shaped string between the heat-shrinkable film and the inner tube. The state diagrams in the case of interposition, FIGS. 5 to 7, respectively show side views of the states after heating in the states of FIGS. 2(a), 3, and 4. Patent applicant Showa Denko Co., Ltd. Representative Patent attorney Sei Kikuchi

Claims (3)

[Claims] (1) In a method of inserting an inner tube into an outer coating tube and exposing and fixing both ends of the inner tube, an end of the outer coating tube in at least one of the exposed portions of the inner tube. A method for fixing an outer layer tube for covering and an inner tube, characterized in that a portion close to the inner tube is surrounded with a heat-shrinkable film, and the film is heat-shrinked to tightly adhere to the outer circumferential surface of the inner tube. (2) The outer layer tube and inner tube for coating according to claim 1, wherein the heat-shrinkable film is a tubular heat-shrinkable film made into multiple layers by folding back the end side of the outer layer tube for coating. Fixed method with. (3) For the coating according to claim 1 or 2, a cord is attached to the entire outer surface of the inner tube near the end Q of the outer layer for coating before surrounding it with a heat-shrinkable film. Fixation method for outer layer tube and inner tube.