JPS5825580B2 - Kantai Gaimen Nihatsupou Plastics - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming a foamed plastic coating layer, for example as a heat insulating layer, on the outer surface of a tube.

BACKGROUND ART Conventionally, heat insulating caps in which a heat insulating coating layer having a low thermal conductivity such as asbestos, glass fiber, foamed polyurethane, or foamed polyethylene is formed on the outer surface of a tube have been used for various purposes.

In particular, long flexible insulated pipes are made by forming a heat insulating coating layer on a corrugated metal pipe or polyolefin plastic pipe in a continuous process and then applying a protective sheath on top. It is useful for heat retention or freezing prevention in water pipes in cold regions.

When manufacturing these insulated pipes, it is especially necessary to continuously cover long pipes with a heat insulating layer, so conventionally the material forming the heat insulating layer is formed into a pipe shape in advance to match the external shape of the pipe. Insert the material into the target pipe body, or wrap a strip of material spirally around the outer surface of the pipe body, or wrap it vertically so that the seam line is straight, and then heat-seal the seam part. A covering layer is formed using the thin strip-shaped insulation material, which is divided into multiple layers to cover the insulation material, as it becomes difficult to wrap the insulation material vertically, especially when the thickness of the material becomes thicker. .

In the case of winding the covering layer using the above-mentioned vertical splicing method, there is no restriction on the size of the presser of the band-shaped heat insulating material as in the case of spiral winding, and the seam line is a straight line along the tube axis direction. Therefore, it is thought that continuous heat fusion can be easily achieved by passing a heated thin plate through the seam joint surface or by blowing hot air. The pipe body is located inside the strip-shaped heat insulating material, and the pipe body is placed inside the strip-shaped heat insulating material. Therefore, it is difficult to prevent the heat insulating layer from becoming loose, otherwise the seam joint will open in a figure 7 shape and the heat fusion will not be good.
Additionally, if you try to bring the seam joints into full contact, the formed heat insulating layer will become loose against the pipe body, and even if you press the heat insulating layer from the surroundings, it will only compress the part on the pipe body side, and the joint will come into full contact with the pipe body. On the other hand, in the case of continuous straightening, there was a problem in that friction against running increased.

This invention solves the above-mentioned problems, and when forming a foamed plastic coating layer vertically on the outer surface of a tube body, even if the tube body exists in the coating layer, the seam joints can be heat-sealed by bringing the entire surface into contact with each other. Therefore, it is an object of the present invention to provide a method for forming a foamed plastic coating layer on a tube body without loosening.

That is, to describe this invention in detail with reference to the drawings, FIG. 1 is an explanatory diagram of the coating process according to the invention, and in the figure 1 is a long tube body that is continuously fed to the line. A foamed plastic coating layer is formed on the outer surface.

In the method of the present invention, this foamed plastic covering layer is applied to the tenth foamed plastic strip 2 and the second foamed plastic strip in the illustrated example.
The foamed plastic strip 4 is formed as a two-layer composite layer.

That is, the first band-shaped body 2 has a width dimension shorter than the outer circumferential dimension of the tube body 1, and is vertically attached and wound around the outer surface of the traveling tube body 1 by the first forming device 3.

Therefore, in this case, as shown in FIG. 2, the first band-shaped body 2 does not cover the entire outer surface of the tube body 1, but continues in the axial direction of the tube body 1 with a gap having a width between both side edges. A cutout portion 9 is formed.

The second band-shaped body 4 is the first band-shaped body wound around the tube body 1.
It has a width equivalent to the outer circumference of the strip 2, and is vertically attached and wound on the first strip 2 by the second forming device 5 so that its seam line is located on the notch 9. When combined, the state shown in FIG. 3 is obtained.

At the rear of the second forming device 5, the second band-shaped body 4 has its seam line portion 10 directed from the outside toward the center of the tube by a push plate 7 provided integrally with or separately from the forming device 5. Pressed.

In this case, since the above-mentioned notch 9 is located at the lower part of the inner surface of the seam line portion 10 of the second strip 4, the notch 9 of the second strip 4 is pressed by the pressing plate 7 as shown in FIG.
The upwardly protruding edges on both sides are pushed toward the center of the tube,
As a result, the end surfaces of the both side edges come into contact with each other throughout the thickness direction, and full-surface contact of the seam joint surfaces is achieved.

The seam line portion of the second strip 4 that is in full contact as described above is heated and melted in the thickness direction by the heating thin plate 6 of the fusing device 8 disposed immediately after the push plate 7, and While passing through the holding part 11 of No. 8, it is cooled and heat-sealed to be joined.

Therefore, by this heat fusion, two foamed plastic coating layers are formed on the outer surface of the tube body 1 as shown in FIG. If the seam line is positioned vertically and the ends are rolled together, the joint surface can be opened into a V-groove shape by similar forming and pressing.

In this case, the press plate 7 may be integrally provided in the fusing device 8 in front of the thin heating plate 6.

The above-mentioned notch 9 essentially creates a gap in the coating layer, but in this invention, the notch 9 is formed only in the innermost coating layer, so it is difficult to use, for example, as a heat insulating pipe. It does not have a substantial effect on the heat insulation effect in the application, and since there is an outer layer with the seam completely fused on the entire surface of the notch 9, there is little fear of water infiltration, and the outermost layer If you cover it with a protective sheath, you will no longer have to worry about that.

In the above description, an example is shown in which a knife-shaped flat plate is used as the heating thin plate 6, but in this invention, as described above, the notch 9 is formed directly below the seam line of the second strip 4 to be fused. Therefore, for example, it is possible to attach a horizontal thin heating plate to the lower end of the thin heating plate 6 and heat-seal not only the seam joint surface but also the contact surfaces of the first and second strips on both edges of the notch 90 at the same time. This is possible, and if the fusing device 8 is provided with a cooling air supply mechanism to feed cooling air to the rear of the heat-fused portion through the notch 9, the notch 9 can be effectively used. The cooling used can even speed up the solidification of the fusion,
As a result, it is possible to increase the line speed.

As described above, according to the present invention, it is extremely easy and reliable to continuously form a foamed plastic coating layer on a long pipe body, and it is possible to prevent defective joints from being formed on the outer surface of the coating layer. Therefore, it is possible to create a structure that can effectively prevent water from entering into the coating layer from the outside.Also, since a notch is formed in the innermost layer and communicates with the pipe in the axial direction, this notch can be As a result, not only can the production speed be increased, but also the thermal expansion and contraction of the tube can be absorbed by the notch, making it possible to cool the coating layer. This can have great industrial effects, such as eliminating the risk of damage.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a coating process showing an embodiment of the present invention;
Figures 2, 3, 4, and 5 are A-A of Figure 1, respectively.
, BB, CC, and DD line arrow sectional views. DESCRIPTION OF SYMBOLS 1... Pipe body, 2... First foamed plastic strip, 3... First forming device, 4... Second foamed plastic. Band-shaped body, 5.
... Second forming device, 6 ... Heating thin plate, 7 ... Push plate, 8 ... Fusion device, 9 ... Notch part, 10... seam line part, 11... joint holding part.

Claims (1)

[Claims] 1. A foamed plastic strip shaped like a flat plate or cut vertically in advance and formed into a tubular shape is wrapped around the tubular body vertically, and the seam line of the strip along the axial direction of the tubular body is heat-sealed. When forming a foamed plastic coating layer on the outer surface of the tube, a plurality of foamed plastic strips are used to form a plurality of coating layers, and the inner coating layer has continuous notches along the axial direction of the tube. A foamed plastic strip is vertically wrapped around the inner layer so that the seam line is located in the middle of the width of the notch, and the seam line portion is formed from the outside. A method for forming a foamed plastic coating layer on the outer surface of a tube, the method comprising further forming a coating layer on the inner layer by heat-sealing the seam line portion while pressing toward the center of the tube.