JPH0334386B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a treatment method for coating the inner surface of various metal pipe materials with different materials.

[Prior Art] Conventional methods for coating the inner surface of pipe materials include the following methods, but each method has the following drawbacks.

(1) Method using extrusion method This method uses a composite extrusion billet in which an inner layer and an outer layer are combined in advance and is extruded to form a composite tube (double tube) whose inner surface is coated with different metals. This method is disadvantageous in terms of manufacturing cost because the manufacturing process includes a composite billet manufacturing process, an extrusion process, and a drawing process for reducing the diameter to a predetermined size. Furthermore, if the metal covering the inner surface is a low melting point metal, it may melt due to the heat of deformation during extrusion molding, making it impossible to obtain a normal composite tube. Furthermore, if there is a large difference in deformation resistance between the tube base material and the covering material during extrusion, there are drawbacks such as difficulty in normal extrusion and pultrusion.

(2) Internal plating method In this method, it is possible to apply electroplating to the inner surface of the tube by pouring a plating solution for the metal to be coated on the inner surface of the tube, but in order to process long pipe materials, the plating solution is It is not suitable for industrial production because concentration management, current density management, etc. are complicated.

(3) Welding method This method involves seam welding the pipe material and sheathing material into a tubular shape with the sheathing material side inward. Welding is difficult, and the coating metal is exposed on the outer surface of the tube at the seam weld, making it impossible to obtain a uniform coating layer on the inner surface of the tube.

[Problems to be Solved by the Invention] The purpose of the present invention is to solve the above-mentioned drawbacks of the prior art and to provide a process that is excellent in industrial production and can uniformly coat the inner surface of a long pipe with a different substance. The purpose is to provide a method.

[Means for Solving the Problems] In order to achieve the above object, the present invention adopts the following measures.

That is, a tube material having a plurality of grooves or protrusions extending in the longitudinal direction is used on the inner surface of the tube material, and a liquid substance or a paste-like substance mixed with a liquid substance and a powdery solid substance is coated on the inner surface of the tube material. Therefore, a method is adopted in which a liquid or paste-like substance and a plug are inserted into a tube, and the substance is continuously applied to the inner surface of the tube with the plug while the tube is pulled out through a die.

In this case, the grooves or protrusions on the inner surface of the tube work effectively to ensure the amount of coating that adheres to the inner surface of the tube, but their shape, number, size, etc. are not particularly limited. However, the practical groove depth or protrusion height is preferably 0.001 mm to 0.5 mm. in this case
If it is less than 0.001mm, the effect of the groove or protrusion is small;
Moreover, if it is 0.5 mm or more, the amount of adhesion will be too large, which is not practical.

Whether the grooves or protrusions on the inner surface of the tube are parallel to the longitudinal direction of the tube or in a spiral shape do not affect the characteristics of the present invention. The grooves or protrusions do not need to be continuous in the longitudinal direction of the tube material, but may be discontinuous, or the grooves or protrusions may intersect with each other.

As the tube material, Cu, Al, Ti, Mg, Fe, or an alloy containing one of these as a main component is used.

By using the technology of the present invention, it is possible to improve the corrosion resistance of the inner surface of the pipe material and the strength of the pipe material.
It can be applied as a method for treating the inner surface of pipe materials such as supply pipes for liquids such as oil, supply pipes for gas bodies such as combustion gas, or heat transfer pipes and pressure transfer pipes that utilize heat transfer inside and outside the pipe.

[Embodiments of the invention] Examples of the present invention will be described below.

FIG. 1 shows an example of applying a thin layer 7 of liquid paint 3 to the inner surface of a metal tube 1.

As shown in FIG. 2, the metal tube 1 has a plurality of protrusions 2 extending spirally or linearly on its inner surface, and is placed in a fixed position with a plug 5 and a paint 3 placed inside. It is moved through the fixed die 4 in the direction of the arrow and pulled out. in this case,
The paint 3 is carried forward as the tube 1 moves, but most of it is squeezed by the tube 1 and the plug 5 in the die 4 and remains behind. Since this is done by the lubricating paint 3 between the pipe 1 and the plug 5, no special lubrication treatment is required. When the tube 1 passes through the die 4, the protrusion 2 on the inner surface ensures a gap between the tube 1 and the plug 5, so that the paint 3 on the inner surface of the tube 1 is
The thin layer 7 can be formed reliably.

FIG. 3 shows another example of a pipe material that can be used, and the protrusions 2 may be sparse as in a and b, or densely formed as in c. Alternatively, as shown in FIG. 4, the grooves may intersect and the protrusions 2 are regularly present.

Next, it will be explained in detail.

Example 1 In order to coat the inner surface of a steel pipe with an outer diameter of 9.52 mm, a bottom wall thickness of 0.41 mm, an inner diameter of 8.40 mm, and an inner protrusion height of 0.15 mm with a thin layer of corrosion-resistant paint, a commercially available liquid paint was applied using a die and a plug. A thin layer of paint was applied to the inner surface of the steel pipe by drawing and drawing the pipe to an outer diameter of 8.8 mm.

[Effects of the Invention] As is clear from the above description, the present invention is a method of using a pipe material having grooves or protrusions on the inner surface, inserting a plug into the pipe, and applying paint with the plug while drawing a die. , inner-coated cladding tubes can be manufactured continuously using simple equipment, and long products can be easily manufactured. Another advantage is that the inner surface coating material can be easily replaced, making it suitable for small-lot production of a wide variety of products.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an example of a method of applying a mixture in the method according to the present invention, and FIGS. 2, 3, and 4 are sectional views showing examples of pipe materials used in the present invention, respectively. 1 and 6: tube material, 2: protrusion, 3: liquid, 4:
Dice, 5: Plug, 7: Thin coating layer of liquid.

Claims (1)

[Claims] 1. A method of coating a metal tube having a plurality of grooves or protrusions extending in the longitudinal direction of the tube on its inner surface with a liquid or a paste-like substance obtained by mixing a liquid substance and a powdery solid substance, the method comprising: A method for treating the inner surface of a metal tube, the method comprising: inserting a paste-like substance and a plug into the metal tube, and applying a paste-like substance to the inner surface of the metal tube using the plug while drawing the metal tube through a die.