JPS58135723A - Manufacture of plastic lining corrugated metallic pipe - Google Patents

Abstract

PURPOSE:To obtain a titled corrugated metallic pipe which has a lining layer of uniform thickness and has a good performance, by compressing a corrugated metallic pipe to which plastic lining working has been performed, in a prescribed crest ratio in the axial direction. CONSTITUTION:At first, to a corrugated metallic pipe to which lining treatment can be executed by a conventional method, plastic lining is performed. Subsequently, the corrugated metallic pipe 1 to which lining working has been performed is compressed in the axial direction until its crest ratio (crest/pitch) H/P becomes >=0.5 as shown in the figure (a) and (b), by which an object plastic lining corrugated metallic pipe is obtained. In this regard, in case of compression, when the crest ratio of the metallic pipe is made large enough, or in case it is considered feasible that peel-off occurs due to small adhering strength between the lining layer and the surface of the metallic pipe, an adhesive agent is applied onto the surface of the metallic pipe prior to lining of plastic. As for this adhesive agent, for instance, polyamide resin, acrylic resin, etc. are used.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for bunosing and tick lining the surface of a corrugated metal pipe.

Plastic-lined metal pipes have been put into practical use for a long time, in the case of straight metal pipes, for the purpose of providing corrosion resistance and aesthetic appearance due to the properties of the plastic used for the lining.

Methods for lining straight metal pipes with plastic can be roughly divided into powder coating methods, in which plastic powder is heated and fused to the surface of the metal pipe, and so-called plastic pipe coating methods, in which the metal pipes are directly coated with plastic by extrusion or the like. The former category includes the fluidized dipping method, flame spray method, etc., as well as the electrostatic coating method, in which plastic powder is colored on a metal tube using a spray gun under high voltage, and then electrically adhered to the tube surface and then heated and melted. There is. Of the latter methods of coating plastic pipes, the most common methods for coating the outer surface of metal pipes include extrusion coating or heating after passing the metal pipe through a heat-shrinkable plastic tube. When coating the inner surface of a tube, there are two methods: passing it through a thermally expandable tape tube and expanding it, and a cold application method.

Furthermore, there is also a dispersion method in which a suspension of powdered resin is sprayed onto the inner and outer surfaces of a metal tube and then heated and baked.

Plastic lining for corrugated metal pipes is essentially difficult to line with a uniform thickness because the metal surface is not smooth, or the relationship between the height H of the corrugations and the pitch P of the corrugations H/P When the wave height ratio (hereinafter referred to as the wave height ratio) is sufficiently between I'' and 11, it can be handled almost in the same way as a straight pipe.

For example, metal pipes are corrugated using a roll method, but in this case the wave height ratio is 0.2 to 0.
．． About 5 fakes are manufactured, and in the case of corrugated metal pipes with a wave height ratio in this range, it is often possible to apply the conventional straight pipe 2-inning technique.

As the wave height ratio in corrugated metal pipes gradually increases, it becomes difficult to form a uniform lining layer, and there are cases where it becomes impossible to form a continuous lining layer, which is difficult to achieve with conventional methods. It becomes too much to handle.

One possible solution to this problem is to line a straight metal pipe in advance, then apply corrugation to it, and compress it further in the pipe axis direction if necessary. However, with this method, the lining layer and the metal surface are This is undesirable because peeling may occur in the lining layer, or residual stress strain remains in the lining layer, particularly in the peaks and valleys of the tube surface, which may cause cracks to occur in the lining layer over time.

The present invention addresses and solves the technical problems of the conventional methods as described above.Through extensive research, we have developed a plastic that has a relatively uniform lining layer thickness even when the wave height ratio is large and has excellent performance. We have discovered a method for manufacturing lined corrugated metal tubes.

The present invention will be described below with reference to the drawings. Figure 1 shows the cross section of a corrugated metal tube, which is round and has a wave height H and a wave pitch P.
This is what is shown.

Wave ratio H that could not be manufactured using conventional methods
/ P s For example, when manufacturing a plastic-lined corrugated metal tube larger than 0.5, a plastic lining is first applied to a corrugated metal tube that can be subjected to two-inning treatment by a conventional method, and then the plastic lining is applied as shown in FIG. )
Or, as shown in koji, by compressing this in the axial direction until a predetermined wave height ratio is reached, a corrugated plastic lining v Jll 'gr is obtained. This compression step can also be carried out by inserting a guide by two inside the corrugated metal tube, as shown in FIG.

If a plastic-lined corrugated metal tube is manufactured according to the method of the present invention, the plastic lining layer is concentrated particularly in its peaks or valleys, compared to the conventional method of manufacturing a plastic-lined metal straight tube by processing. The absolute value of the stress caused by the lining becomes smaller, and the plus book of the lining layer not only absorbs the stress sufficiently and does not cause cracks, but also the thickness of the second lining layer can be easily adjusted during the initial lining operation. be able to.

When compressing, when the wave height ratio of the metal tube is sufficiently large to make it round, or when there is a risk of peeling due to low adhesive strength between the second lining layer and the surface of the metal tube, use a plastic lining. Prior to this, adhesive is applied to the surface of the metal tube.

As adhesives for this purpose, it is possible to use synthetic resin adhesives with some plasticity, such as polyamide resins, acrylic resins, modified polyethylene/or ethylene vinyl acetate resins.

There are no particular restrictions on the plastic used to coat the surface of the metal tube, and any material can be used as long as it can sufficiently absorb the stress and strain received during the compression process.
For example, polyethylene, crosslinked polyethylene, bolyaid,
Polytetrafluoroethylene, polypropylene, bentone (trade name), polyvinyl chloride, and from these
A mixture of two or more selected types or a synthetic resin containing these resins as main components and other modifying components is used.

When manufacturing a plastic-lined corrugated metal tube according to the present invention, if a metal tube with a large wave height ratio is to be obtained, use a corrugated metal tube to be lined in advance with a wave height ratio of about 0.2 or more, so that pressure wire processing is possible. It's a lonely island. Oka, the shape of the wave in a metal pipe VC is different whether it is an independent arc lid or a spiffle type.

The present invention will be explained in detail below with reference to Examples.

Exception: A 1125 m 11% wall thickness 0.3 - steel pipe (this is referred to as A) is corrugated to an outer diameter of 25 mm, an inner diameter of 20 mm, a wave jli of 2.2 mm, and a pitch of 5 wh (H/P -0,44). Processed nine (this is called B). Next, B is further compressed in the axial direction to have a wave volume of 2.7 cm and a pitch of 2.71111 (H/P = 1).
A corrugated steel pipe (referred to as C) was obtained.

For the above-mentioned steel pipes B and C, 18 I# inflatable polyethylene tubes with an outer diameter and a thickness of 0.5 mm (the outer surface is coated with modified polyethylene of a thickness of 0.2 mm as an adhesive layer). When the lining process was performed by applying pressure and heating, A and B were completely lined, but in case C, the tube was not fully lined at the peak of the corrugated tube. It was impossible to line it because it could not be stretched completely and broke.

The obtained mold was first corrugated until it had the same shape as B, and then compressed and processed until it had the same shape as O.

B, on the other hand, was also compressed with a trench that had the same shape as C.

When the plastic-lined corrugated steel pipes obtained as described above were subjected to a heat cycle test in which a thermal history of OC to 80C was applied five times for 30 minutes each, there was no change in B (in contrast,

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a corrugated metal tube, Figure 2 is also), (1:+)
and Fig. 3 is an explanatory cross-section Ii of a scene in which a corrugated metal tube is compressed.
It is wA. l... Corrugated metal pipe, 2... Compression guide representative patent attorney Masatoshi Sato

Claims (1)

[Claims] A corrugated metal tube is processed with plastic lining, and then the tube is axially lined with a wave height ratio (wave height/pitch) of at least 0.
．． A method for manufacturing a corrugated metal tube whose inner surface is lined with plastic, characterized by compressing the tube to a temperature of 5%.