JPH11291080A - Manufacture of metallic tube having joint part - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the productivity by forming a tube body part of a steel tube, pouring the molten metal into a mold to form a joint part, welding a part to be separated of the joint part from the tubular part, cutting or grinding the welded part after the heat treatment to manufacture a metallic tube having the joint part and to easily apply the resin to an inner circumferential surface of the tube. SOLUTION: A tube body part 7 is formed of a steel tube of the specified diameter, thickness and length using a stock of a steel plate or a steel strip, a socket part 4 is provided with a short tube 2 of the same shape as that of the part 7 and a flange 3, and its material is formed of spheroidal graphite cast iron of direct weldability. A side surface of the short tube 2 of the socket part 4 is directly connected to a side surface of an end of the tubular part 7 by flash-butt welding to constitute an original metallic tube having a flange-shaped socket. After the temper heat treatment is executed around the welded part through the direct energization heating or the high frequency induction heating at the temperature between approximately 400 deg.C and the A1 transition point, a third lip 9 generated on an outer circumference in the tube at the welded parts are mechanically cut to manufacture the metallic tube having the flange-shaped socket.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

This metal pipe with a joint is mainly provided with a joint at one end as a transport pipe for water supply water, agricultural water, industrial water and the like. Generally, the same metal pipe with a joint is used. To be used as a pipeline.

[0002]

2. Description of the Related Art In the case of a steel pipe having a joint, the joint is formed at one end of the steel pipe with a large-diameter receiving port formed on an outer periphery of the same pipe as the outer pipe through a rubber ring so as to be connectable to an exterior. I came. Therefore, the thickness of the socket is thinner than the pipe,
There is a problem in the practical use strength as a joint part, and the port is generally required to continuously form an extreme internal diameter change in the axial direction inside the port due to its function. Because it is technically impossible to form the inside of the receptacle in the state,
This type of steel pipe with joints is rarely used

[0003] Spheroidal graphite iron tubes with joints are almost directly or indirectly produced today by centrifugal casting using a mold. Therefore, there is no problem regarding the formation of the socket of the steel tube with joints. The pipe body is as tough as a steel pipe. Until now, in order to prevent rust in the pipe and preserve the water quality of the transported water, the inside of the pipe has a mortar-lined spherical graphite with joints and various receiving ports. Cast iron pipes have become the mainstream of all demand and their production, and have been used as various water transport pipes nationwide since about 1959.

[0004] Occasionally, from around 19603, the degree of economic growth gradually accelerated, and the deterioration of the quality of the raw water transported in the pipeline began to progress nationwide. Immediately before transportation on the road, the amount of chlorine added to the source water was gradually increased in accordance with the degree of deterioration of the water quality. As a result, the water flowing in the pipes gradually becomes more acidic, and the mortar lining applied to each pipe begins to erode, and the water in which the mortar is dissolved promotes new deterioration of water quality. Again, complaints from the above-mentioned water demand related persons have begun to increase again nationwide, and it is expected that serious social problems will occur.

As a countermeasure against the above-mentioned problem, a manufacturer of spheroidal graphite cast iron pipes with joints has been urgently required to produce spheroidal graphite cast pipes with joints in which an acid-resistant resin is applied inside the pipes instead of the mortar lining. I have begun. However, spheroidal graphite cast iron tubes with joints are produced by centrifugal casting of a mold or a mold similar to a mold. The inner circumferential surfaces of the pipes receive the interference of the radiant heat of the symmetry planes in high-temperature hot air, and are relatively slowly solidified while receiving centrifugal force. Therefore, a large strain is built in the outer circumference of the tube. At the same time, the inner peripheral surface of the tube is significantly different from the inner solidified surface formed by pouring into the mold of the molten metal, and an oxide film with fine and complicated wrinkles is formed irregularly over the entire inner peripheral surface. The slag solidifies in a complicatedly entangled state.

[0006] In order to make the spheroidal graphite cast iron tube with a joint part as it is cast into a practical tube, the entire tube is first 900 deg.
After annealing at ~ 1000 ° C for several hours, a heat treatment is performed to cool slowly, and then the oxides and slags generated and fixed on the inner peripheral surface of each tube during centrifugal casting are sufficiently removed for resin coating in the tube. The surface preparation work has exclusively used tools such as grinders and shot blasts.

However, pipe types that require emergency in-pipe resin coating have a nominal diameter of 75 to 3 which accounts for approximately 70% of the total demand.
With a diameter of 00 mm and a pipe length of 3 m or more, it concentrates on the small-diameter pipes in the range where the preparation processing is most difficult in the pipe, and the preparation efficiency does not progress slowly. The demand for spheroidal graphite cast iron pipes with joints coated with resin in the pipes continues to be a major obstacle, and today, producers and consumers alike continue to take measures to overcome these problems.

[0008]

In view of the above-mentioned problems associated with resin coating on the inner peripheral surface of a spheroidal graphite cast iron tube with a joint by centrifugal casting, a completely new productivity that makes it possible to easily apply resin coating on the inner peripheral surface of the tube. Provided is an excellent method for manufacturing a metal tube with a joint.

[0009]

A metal pipe with a joint portion is separated into a joint portion and a tube portion, and the tube portion is formed of a required steel pipe with a steel plate or the like. The material of the joint portion is similar to the physical properties of the steel pipe, and a casting of a metal material having a castability of the receiving material itself is poured into a mold to form a joint portion. By welding a place in the separated state to the above-mentioned joint part and the pipe body part, and turning the weld place after the heat treatment of the weld place, or grinding the weld place to produce a metal pipe with a joint part.
The undercoating work of the grease coating in the metal tube with the joint can be performed very easily.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described based on Embodiment 1 with reference to the drawings. The metal pipe 1 with a flange-type socket is separated into a socket 4 and a pipe 7, and the pipe 7 is made of a material such as a steel plate or a steel strip and has a required pipe diameter, pipe thickness, and pipe length. The receiving part 4 is provided with the short pipe 2 and the flange 3 having the same tubular shape as the pipe part 7, and the material thereof is closest to the metallic properties of the steel pipe material, and is directly welded between the two. Of molten spheroidal graphite cast iron into a self-hardening mold. The side surface of the short pipe 2 of the receiving portion 4 and the side surface of the pipe end 5 of the pipe body portion 7 are directly connected by flash butt welding to form the original tube 8 of the metal tube 1 with a flange type receiving portion. . Direct current heating or radio frequency induction heating around the its welds 11, A ₁
After performing a tempering heat treatment at a temperature within a range of about 400 ° C. from the transformation temperature, the third lip 9 generated on the inner and outer circumferences of the pipe at the welding point during the above welding is mechanically turned to form a metal pipe 1 with a flange type socket. To manufacture.

Embodiment 2 will be described with reference to the drawings. The socket-type metal pipe with a socket 1a is separated into a socket 4a and a pipe 7a, and the pipe 7a is made of a material such as a steel plate or a steel strip and is a steel pipe having a required pipe diameter, pipe thickness, and pipe length. Forming
The same short tube 2a and socket-type socket 3 as the tube portion 7a.
The molten metal of spheroidal graphite cast iron, which is closest to the metallic properties of the steel pipe material and has direct weldability between the two, is poured into a self-hardening mold, and the socket-type socket 3a is formed. The short tube 2a side surface and the side surface of the tube end 2a of the tube portion 7a are directly connected by flash-butt welding to form the original tube 8a of the metal tube 1a with the socket type socket. By its directly around the weld portion 11a electrically heating or high frequency induction heating treatment, after the A ₁ transformation temperature was subjected to tempering heat treatment at a temperature within about 400 ° C. between range, it welds 1 during the welding
The third lip 9a generated on the inner and outer circumferences of the pipe 1a is mechanically turned to manufacture the metal pipe 1a having a socket-type socket.

[0012]

Effect 1 According to the method for manufacturing a metal pipe with a joint portion of the present invention, the joint portion, which is the various receiving portions, is formed by pouring a molten spheroidal graphite cast iron into a required mold. Using the required copper pipe, the above-mentioned joint, the pipe body and the side lip generated on the inner and outer circumferences of the pipe at the time of butt welding are easily removed from the inner and outer circumferences of the pipe at the short pipe position of the joint. Both the receiving portion and the inner peripheral surface of the tube are smoothly connected. Therefore, the undercoating process of the resin coating on the inner surface of the tube formed above is only to remove a thin oxide film and other fine deposits formed on the inner surface of the tube immediately before resin coating. The work can be completed in a very short time only by using the shot blast mechanically for a short time.
Therefore, a large problem such as the resin coating groundwork on the inner peripheral surface of the spheroidal graphite cast iron pipe with a joint can be solved very easily and reliably. In the case of the method for manufacturing a metal pipe with a joint according to the present invention, no undulations or the like are formed on the inner peripheral face of the spheroidal graphite cast iron pipe at the time of centrifugal die casting. Therefore, the amount of the resin paint used for coating the inner peripheral surface of the pipe can be reduced by about 10 to 30% of the conventional amount.

Effect 2: In the case of the conventional production of a spheroidal graphite cast iron tube with a joint, the spheroidal graphite cast iron melt is formed by centrifugal casting in a mold, and the original tube is formed by using a fuel such as heavy oil. Heat annealing treatment has been carried out for several hours at about 900 to 1000 ° C., but by carrying out the manufacturing method of the present invention, all facilities related to the above-mentioned annealing treatment and related various expenses are completely eliminated. Therefore, C generated from the above-mentioned annealing furnace operation
O2 does not occur.

Effect 3: In Japan, the spheroidal graphite cast iron pipe with a joint is made by dissolving at least the raw material pig iron material in cupola ⇒ graphite spheroidizing the molten metal ⇒ centrifugal casting of the pipe ⇒ high-temperature annealing heat treatment of the pipe And other major production operations have been carried out in a consistent, chain-linked, large-scale production facility manufacturing method.
At least in Japan, there are many excellent companies that produce spheroidal graphite cast iron pipe joints and steel pipes equivalent to spheroidal graphite cast iron pipe pipes, and their production capacity is large, These related products are always in the strong buyer market, and it is easy to procure the above-mentioned spheroidal graphite cast iron joint members and steel pipe materials. It is possible to implement a manufacturing method, and it can be expected that the running cost for producing the spheroidal graphite cast iron tube is significantly reduced as compared with the conventional manufacturing method.

[Brief description of the drawings]

FIG. 1 is a front view of a part of a tube 7 which is longitudinally sectioned.

FIG. 2 is a side view of the tube 7 seen from the insertion portion 6 side of FIG.

FIG. 3 is a front view of a longitudinal section of a part of a flange type receiving portion 4 as a pipe joint.

FIG. 4 is a side view of the socket 4 seen from the short pipe 2 side in FIG.

FIG. 5 is a front view of a part of the original tube 8 in which the receiving portion 4 and the tube 7 are directly butted and resistance-welded to the two short sides of the tube and the five ends of the tube end.

FIG. 6 is a front view of the metal tube 1 with a flange type receiving port.

FIG. 7 is a front view of a part of a receiving portion 4a, which is a joint portion, in a longitudinal section.

8 is a side view of the socket 4a as viewed from the short pipe 2a side in FIG.

FIG. 9 is a side view of the tube 7a viewed from the tube end 5a.

FIG. 10 is a front view of a part of the tube 7a.

FIG. 11 is a front view of a part of a metal tube 1a with a socket-type receptacle, which is longitudinally sectioned.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Metal tube with a flange type receptacle 1a Metal tube with a socket type receptacle 2 Short pipe 2a Short pipe 3 Flange 3a Socket type receptacle 4 Reception part 4a Reception part 5 Pipe end 5a Pipe end 6 Insert part 6a Insert Part 7 Tube part 7a Tube part 8 Raw tube 8a Raw tube 9 Third lip 9a Third lip 10 Welded part 10a Locking ring 11a Welded part

Claims (1)

[Claims] 1. A short pipe provided at a joint part, a metal pipe with a joint part constituted by connecting a pipe of a pipe part and a side surface of each pipe, the pipe part is formed of a steel plate with a steel pipe, The joint is formed by pouring a molten graphite cast iron into a mold, butt-welding the short side of the joint and the side of the steel tube to each other, and tempering the weld by local heating. A method of manufacturing a metal pipe with a joint portion, wherein the third lip generated on the inner and outer circumferences of the pipe at the time of welding is removed at the welding point.