JP2778908B2 - Insertion stopper ring joining method of cast iron pipe - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of joining an insertion stopper ring for preventing a connection part from being detached from an outer peripheral surface on a connection end insertion side of a cast iron pipe.

[0002]

2. Description of the Related Art Generally, as shown in FIG. 2, an insertion stopper ring 12 made of steel or tough cast iron (for example, ductile cast iron) is provided on a connection end portion of a cast iron pipe 11, particularly an outer peripheral surface 11A on an insertion side. It is fixed. This stopper ring 12
This is to lock this with a lock ring 15 fitted in a groove 14 formed in the inner peripheral surface 13A of the receiving port 13 which is the other party so that the connection portion does not come off.
Reference numeral 16 denotes a backup ring for holding the lock ring 15 in the groove 14.

Conventionally, the insertion stopper ring 12 is fitted in a groove formed by turning on the outer peripheral surface 11A of the insertion port of the pipe 11 with a slit formed at one location in the circumferential direction.
As shown in FIG.
In order to form the abutment surface 12A with the 5, a work of forming a corner 18 by lathing as shown in FIG. 3B may be performed.

[0004]

In the prior art described above, the joining strength of the insertion stopper ring is not sufficient. Particularly, when the outer peripheral surface is turned to form a corner of the contact surface of the lock ring 15, the strength is insufficient. Is remarkable. The present invention has been made in view of the above situation, and its purpose is to
An object of the present invention is to provide a method for joining an insertion stopper ring of a cast iron pipe, which does not require groove processing and enables high-strength joining.

[0005]

According to the present invention, the following technical measures have been taken in order to achieve the above object. That is, the present invention relates to a method of joining an insertion stopper ring for preventing a detachment of a connection portion to an outer peripheral surface of a connection end portion of a cast iron pipe on an insertion side, and comprising an outer peripheral surface of an insertion side of the tube and an insertion stopper ring. On at least one of the inner peripheral surfaces, a sprayed metal layer of a metal alloyed with iron is formed, and after fitting an insertion stopper ring made of steel or tough cast iron to the tube via the sprayed metal layer, The invention is characterized in that the pipe and the insertion stopper ring are metallurgically joined to each other through an alloy layer of iron and a sprayed metal by ferrite annealing the pipe.

[0006]

According to the present invention, the sprayed metal layer dissolves during the ferritizing annealing of the cast iron pipe, and at the same time, a pressure is applied to the joint surface where the sprayed metal layer is present due to expansion and thermal expansion caused by transformation of the metal structure of the pipe. Acts to diffuse the sprayed metal to both the outer surface of the pipe and the inner peripheral surface of the insertion stopper ring, forming an alloy layer with iron, and through the alloy layer, the outer peripheral surface of the pipe and the insertion stopper. The inner peripheral surface of the ring is metallurgically joined and integrated.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. 1 (a) to 1 (d) are process diagrams showing an embodiment of the present invention. First, as shown in FIG. 1 (a), insertion of an as-cast cast iron pipe 1 (100 mm diameter unannealed pipe) On the outer peripheral surface 1A,
After applying a flux such as borax or boric acid, Al is sprayed to form a sprayed metal layer 2 (about 100 μ).

On the other hand, the stopper ring 3 for preventing connection and disconnection is made of rolled steel SS for general structure and has an outer diameter of 136 mm, an inner diameter of 116.5 mm (corresponding to the maximum outer diameter of the pipe), and a width of 15 mm.
A flux (borax, boric acid, etc.) is applied to the inner peripheral surface 3A, and the ring 3 is fitted to the outer periphery of the sprayed metal layer 2 welded to the surface of the cast iron pipe 1 by an insertion means such as a hydraulic jack. To the state shown in FIG.

Next, the cast iron pipe 1 fitted with the insertion stopper ring 3 is subjected to ferritizing annealing in an annealing furnace. The ferrite annealing is the first-stage graphitizing annealing that decomposes cementite (for example, 920 to 980 ° C., 20 ° C.).
), And a second-stage graphitizing annealing (for example, 730 ° C, 60 minutes) for decomposing pearlite to form ferrite was performed in one heating and cooling cycle.

During the ferritizing annealing, the Al-sprayed metal layer 2 is melted, and the cast iron tube 1 expands thermally in addition to the structural expansion due to the decomposition of cementite. 3 are brought into close contact with each other and pressure is applied, so that Al is inserted into the cast iron pipe 1 and the insertion stopper ring 3.
, And an alloy layer 4 of iron and Al is formed as shown in FIG.

After the completion of the annealing of the cast iron tube, the cooled cast iron tube 1
When the section where the insertion stopper ring 3 is mounted is cut and the cross section thereof is observed with a microscope, an iron / aluminum alloy layer 4 of about 230 μ is formed on the insertion stopper ring joining surface, and high strength joining is performed. I was able to confirm that. In addition, the seal ring contact surface 3A had the same squaring as in the case of turning at a substantially right angle to the cast iron pipe 1.

As the thermal spray metal, besides Al, Ni, Cu or the like which alloys with iron can be adopted. The insertion stopper ring 3 is made of a rolled steel material for general structure SS or a special steel such as stainless steel SUS. Needless to say, it can be made of tough cast iron (ductile cast iron). The thickness of the sprayed metal layer 2 may be about 20 to 200 μm, and the spraying can be performed after the flux is applied only to the inner peripheral surface of the insertion stopper ring 3 instead of the outer periphery of the cast iron tube 1. . Of course, both the cast iron tube 1 and the insertion stopper ring 3 may be sprayed. The flux is preferably applied, but can be omitted.

The present invention is not limited to the above-described embodiment, and the pipe includes a joint pipe as a matter of course.

[0014]

As described above, the present invention relates to a method for joining an insertion stopper ring for preventing a connection part from being detached to an outer peripheral surface on an insertion end insertion side of a cast iron pipe. On at least one of the outer peripheral surface and the inner peripheral surface of the insertion stopper ring, a sprayed metal layer of a metal alloyed with iron is formed, and an insertion stopper ring made of steel or tough cast iron is formed on the pipe by spraying a metal layer. After being externally fitted, the tube and the stopper ring are metallurgically joined to each other through an alloy layer of iron and spray metal by subjecting the tube to ferrite annealing. Because of this, the insertion stopper ring can be joined with high strength by utilizing the expansion of the pipe during ferrite annealing in the current manufacturing process, and the conventional groove turning and welding are not required, and the formation of the sprayed metal layer Is very easy because it is extremely easy It is possible to strike decrease.

[Brief description of the drawings]

FIGS. 1 (a) to 1 (d) are process diagrams showing the working order of an embodiment of the present invention.

FIG. 2 is a partially omitted longitudinal sectional view showing a connection structure of a cast iron pipe.

FIGS. 3A and 3B are cross-sectional views of a main part of a conventional example, in which FIG. 3A shows a state in which an insertion stopper ring is welded, and FIG.

[Explanation of Signs] 1 Cast iron tube 1A Outer surface of insertion side 2 Sprayed metal layer 3 Insert stopper ring 4 Alloy layer

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-47-40416 (JP, A) JP-A-64-53765 (JP, A) JP-A-2-80182 (JP, A) JP-A-7- 18409 (JP, A) Japanese Utility Model Showa 59-62885 (JP, U) Japanese Utility Model Showa 62-109856 (JP, U) Japanese Patent Publication No. 57-14736 (JP, B2) (58) Fields surveyed (Int. Cl. ⁶ , DB name) B23K 1/18 B23K 1/19 C21D 9/08

Claims (1)

(57) [Claims] 1. A method of joining an insertion stopper ring for preventing a detachment of a connection portion to an outer peripheral surface on a connection end portion insertion side of a cast iron pipe, comprising: On at least one of the peripheral surfaces, a sprayed metal layer of a metal alloyed with iron is formed, and an insertion stopper ring made of steel or tough cast iron is externally fitted to the pipe via the sprayed metal layer. Characterized in that the pipe and the stopper ring are metallurgically bonded to each other through an alloy layer of iron and a sprayed metal by ferrite annealing.