JPS5831724A - Heat-insulating piping and manufacture of the same - Google Patents

Abstract

PURPOSE:To produce readily and inexpensively a pipe excellent in the heat insulating properties, by blowing a foamable resin onto the inner and outer surfaces of a pipe being vertically held, and blowing a hot air flow upon the foamable resin to foam it. CONSTITUTION:Thin pipes (C) each having a hot air blow-off hole 1 and a foamable resin blow-off hole 2 are arranged inside and outside of the vertically held pipe (A). Then while the pipe (A) is being rotated, and the thin pipes (C) are being moved axially, the foamable resin is blown off through the blow-off holes 2 to form resin layers respectively on the inner and outer surfaces of the pipe (A), and currents of hot air are driven via the holes 1 upon the resin layers to foam them. Thus, the pipe improved in the heat insulating properties by forming the foamed plastic layers respectively on the inner and outer surfaces can be readily and inexpensively obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to insulating piping in a refrigeration cycle and a solar heat circulation cycle, and a method for manufacturing the same.

Conventionally, this type of piping was insulated by covering the piping tube with a heat insulating material (foamed product).

In this case, poor adhesion between the piping and the insulation material will result in a large loss of insulation. Moreover, it had the disadvantage of poor workability.

The object of the present invention is to easily and inexpensively manufacture an insulated pipe that improves the heat insulation properties of system piping and improves piping workability.

According to this invention, the pipe is explained based on the drawing.
As shown in FIG. 1, a foamed plastic layer B is formed on the inner and outer wall surfaces of the plumbing pipe A. The blowing agent is preferably the same as the medium operating in the piping.

FIG. 2 is a longitudinal sectional view of the apparatus used to carry out the invention.

For spraying, a thin tube C is inserted inside the cylindrical pipe A. This thin tube C is provided with two holes of 1.degree. 2 that penetrate through the tube wall, and the foamed resin gel material 3 pumped from the direction a is ejected from the holes 2 toward the inner wall of the pipe. At this time, if the pipe A is rotated, the gel-like substance 3 will uniformly adhere to the inner wall. Next, the thin tube C is moved in the axial direction (arrow 4+ in the figure).

At this time, hot air is blown out from the other hole 1 to perform heating and foaming molding at the same time. If a thicker foam layer is required, this can be achieved by repeating the above operations. The same procedure as above is also carried out for the outside of the pipe.

Note that the resin gel-like substance injected into the hollow tube C needs to be adjusted in advance to have an appropriate viscosity.

This can be easily achieved by controlling the temperature of the preheater 4.

As explained above, this invention has the effect of improving heat insulation by providing a foamed resin layer on the inner and outer walls of a piping pipe, and making it possible to easily and inexpensively manufacture the heat insulating pipe.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view showing the method. A... Piping pipe, B... Foamed resin layer, C... Foamed resin gel outlet, 3... Foamed resin gel material, 4...・Preheating heater.

Claims (2)

[Claims] (1) Insulated piping with a foamed plastic layer formed on the inside and outside walls of the piping. (2) A hollow thin tube with multiple injection holes on the side is inserted into the inside of a vertically held plumbing pipe, and as the pipe is rotated, a gel-like substance of foamed resin is added into the thin tube. The resin is injected under pressure and ejected from one of the ejection holes to adhere to the inner wall of the pipe, and the pipe and the hollow tube are relatively moved in the axial direction to form a resin layer, and at the same time,
Foam molding is performed by blowing hot air out of another blowing hole. A method for manufacturing insulated piping, in which a hollow thin tube similar to that described above is provided on the outside of the pipe, and the following steps are performed in the same manner.