JPH076591B2 - Cast iron pipe fittings - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a cast iron pipe joint used for water pipes, gas pipes, and the like, and in particular, is fitted with a retaining ring in order to improve tensile strength. The present invention relates to a cast iron pipe joint in which a fitting groove is formed.

[Conventional technology]

For example, as shown in FIG. 9, the connection structure by the cast iron pipe joint includes an outer peripheral surface of the insertion side cast iron pipe 101 and a receiving side cast iron pipe joint 102
Between the inner peripheral surface of the, retaining ring 201, auxiliary ring 202,
The gasket 203 is sequentially interposed in the insertion direction, and the push ring 10 is connected to the socket-side cast iron pipe joint 101 via a connecting bolt 103.
There is one in which the gasket 203 is pressed by the 4 toward the retaining ring 201 side. And the cast iron pipe fitting on the insertion side
A fitting groove 107 of the retaining ring 201 is formed on the outer peripheral surface of the 101, thereby preventing the retaining ring 201 from moving. Incidentally, 105 is a fastening nut that is screwed into the connecting bolt 103.

However, in the conventional cast iron pipe fitting, generally, as shown in FIG. 10, a concave portion B'is formed in a mother die A ', and a mold release agent is applied to the mother die A'to form the mother die A'. It is formed by covering the circumference of the ′ with sand S ′, compacting the sand S ′, and pouring the molten metal into the divided sand mold thus obtained. The angle between the bottom surface of the ′ and the rising surface had to be 90 ° or more. Further, since a mold release agent is applied so that the mother mold can be easily removed from the sand mold, as shown in FIG. 11, the mold release agent D'collects at the corners of the recess B ', and is thus manufactured. The retaining ring fitting groove 107 of the cast iron pipe joint formed using the sand mold has a rounded portion at the intersection between the bottom surface and the rising surface, and even if the angle between the bottom surface and the rising surface is 90 °, the I didn't get 90 degrees.

[Problems to be solved by the invention]

However, when the angle between the bottom surface of the retaining ring fitting groove and the rising surface is obtuse, when the thrust load is applied, the retaining ring 201 moves in the direction of coming out of the fitting groove 107, and The angle between the rising surfaces is 90
Even if it is at a degree, if the intersection is rounded, the engagement area of the retaining ring 201 and the fitting groove 107 becomes smaller as shown in FIG. 12, so if the thrust load is applied, the retaining ring 201 However, there is a problem that it is easy to disengage from the fitting groove 107. Therefore, it is also possible to machine the retaining ring fitting groove formed on the cast iron pipe joint in the as-cast condition taken out from the sand mold with a file or a machine to cut the radius between the bottom surface and the rising surface to 90 °. However, since it takes time and cost and the inside of the casting is more fragile than the surface, it is not preferable to scrape off the surface having high hardness by the above-mentioned processing.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a cast iron pipe joint formed with a retaining ring fitting groove in which the retaining ring does not easily come off without much effort and cost. .

[Means for solving problems]

In order to achieve the above object, the cast iron pipe fitting according to the present invention,
In a cast iron pipe joint in which a retaining ring fitting groove is formed, the angle between the bottom surface of the retaining ring fitting groove and the rising surface including the intersection of the bottom surface is 90 ° or less in the as-cast condition. It is characterized by being done.

[Work]

By configuring as described above, the cast iron pipe joint according to the present invention is capable of engaging the retaining ring by making maximum use of the depth of the retaining ring fitting groove, and further, when receiving a thrust load. Moreover, the retaining ring does not move along the engaging surface. Further, when this thrust load is applied, the retaining ring contacts the hard surface of the fitting groove formed in the as-cast condition.

〔Example〕

 Hereinafter, the present invention will be described based on illustrated embodiments.

FIG. 1 shows a partially cutaway sectional view of an embodiment of a cast iron pipe joint according to the present invention, and FIGS. 2 to 4 show an example of a procedure for manufacturing the cast iron pipe joint.

First, as shown in FIG. 2, prepared matrix A ₁ where the angle between the upper surface and the rising surface α was provided around the projection B ₁ of rectangular or trapezoidal shape is 90 ° or more, the matrix A ₁ Using this, a vertically divided sand mold S ₁ (only the upper sand mold is shown in the figure below) is manufactured.

Next, the mother mold A ₁ was removed from the sand mold S ₁ , and as shown in FIG.
A half-annular shell mold E ₁ with a rectangular or trapezoidal cross section as shown in FIG. 5A is fitted into a recess D ₁ formed on the inner peripheral surface of the sand mold S ₁ corresponding to the protrusion B ₁ of the mother mold A ₁ . Let's combine. This shell type
E ₁ is configured to protrude from the inner circumferential surface of the sand mold S ₁ in a state fitted to the concave portion D ₁ of the said sand mold S _1, axial faces e of the protruding portion
The angle β between ₁₁ and the surfaces e ₁₂ and e ₁₃ intersecting with ₁₁ is formed to be 90 ° or less. It may be used an annular shell E ₁ 'as shown in Figure 5B in place of the shell E _1.

Next, the upper and lower sand molds in which the shell mold E ₁ is fitted in the recess D ₁
In a state where the core F ₁ is disposed at the center of the cylindrical hollow portion which is formed by and upper and lower sand mold S ₁ combined S _1, as shown in FIG. 3, the molten metal between the sand mold S ₁ and the core F ₁ Inject G.

Next, when the poured molten metal G solidifies to form the shape of the cast iron pipe joint, this cast iron pipe joint 1 as shown in FIG. 4 is taken out from the sand mold S ₁ together with the shell mold E ₁ , and then the shell mold By destroying E ₁ , the bottom surface as shown in Fig. 1
The angle γ between 2a and the rising surface 2b is
The cast iron pipe joint 1 having the retaining ring fitting groove 2 formed at 90 ° or less is molded.

In addition, the cast iron pipe joint according to the present invention can be manufactured by the procedure using the full molding method as shown in FIGS. 6 and 7.

First, as shown in FIG. 6, corresponding to the retaining ring fitting groove of the cast iron pipe joint to be manufactured, the bottom surface b ₂₁ and the rising surface b
A recess formed by forming the angle between _{22 and} below 90 ° including the intersection
A cast iron pipe fitting model A ₂ having B ₂ is manufactured using Styrofoam.

Next, the shell mold E ₂ is fitted in the recess B ₂ of the model A ₂ . In this case, the model A ₂ is made of Styrofoam,
The shell E ₂ is easily fitted by pushing open the opening of the recess B ₂ .

Next, embed this model A ₂ in the non-dividing sand mold S ₂ ,
As shown, it vaporizes the model A ₂ by injecting molten metal G into _two parts Model A.

When the molten metal G injected into the sand mold C ₂ solidifies to form a cast iron pipe joint, the cast iron pipe joint in which the shell mold E ₂ is fitted in the recess 2 is taken out from the sand mold S ₂ , and then the shell mold E ₂ is destroyed. By doing so, the cast iron pipe fitting 1 shown in FIG. 1 described above can be manufactured.

The cast iron pipe joint according to the present invention is not always manufactured by the method described above. For example, a sand mold is manufactured by using a mother mold having no protrusion B ₁ as shown in FIG. 3 shell type was similar to the projecting portion of the sand mold S ₁ shell type E ₁ shown in FIG., is disposed on the inner peripheral surface of the sand in core form, hereinafter, injecting the melt in the same manner as in the Figure 3 It can also be manufactured by Further, in the method applying the full molding method shown in FIGS. 6 and 7, it is possible to manufacture the same cast iron pipe joint as the model A ₂ without using the shell mold E ₂ , but If the shell mold E ₂ is not used in this way, the angle between the bottom surface of the retaining ring fitting groove and the rising surface is an acute angle, instead of saving the trouble of breaking the shell mold after taking out the cast iron pipe fitting from the sand mold. In this case, the cross-section on both sides of the model is not filled with sand, and as a result, a retaining ring fitting groove with a radius may be produced at this cross-section, so the shell type as described above is used. Is preferred.

In the cast iron pipe joint 1 made as described above, the angle γ between the bottom surface 2a and the rising surface 2b of the retaining ring fitting groove 2 is formed to be 90 ° or less including the intersections of both surfaces. As shown in FIG. 8, the retaining ring 201 fits into the fitting groove 2 by making maximum use of the depth of the fitting groove 2. Therefore, when the thrust load is applied, the retaining ring is firmly engaged with the fitting groove, and a strong retaining force can be obtained. Further, if the angle between the bottom surface 2a of the fitting groove 2 and the rising surface 2b is less than 90 °, that is, if it is an acute angle, the retaining ring is rather tapered to the rising surface 2b when a thrust load is applied. Since it tries to enter the fitting groove 2 along with it, a stronger retaining force can be obtained.

〔The invention's effect〕

As is clear from the above description, according to the cast iron pipe joint of the present invention, the retaining ring fitting groove and the retaining ring are firmly engaged with each other when a thrust load is applied, and a strong retaining force is obtained. be able to. In addition, since the retaining ring fitting groove that engages with the retaining ring when a thrust load is applied is formed in an as-cast state, the surface is hard and may be destroyed by the thrust load. There are few things.

[Brief description of drawings]

FIG. 1 is a partially cutaway sectional view showing an embodiment of a cast iron pipe joint according to the present invention, and FIGS. 2 to 4 are main parts showing an example of a procedure for manufacturing the cast iron pipe joint shown in FIG. FIG. 5A is an enlarged cross-sectional explanatory view, FIG. 5A is a perspective view of a shell type, FIG. 5B is a perspective view of another example of the shell type, and FIGS. 6 and 7 are other manufacturing of the cast iron pipe joint shown in FIG. FIG. 8 is a sectional explanatory view showing a procedure, FIG. 8 is a sectional explanatory view showing a fitting state of the retaining ring fitting groove and the retaining ring of the cast iron pipe joint according to the present invention, and FIG. 9 has a retaining ring fitting groove. Cross-sectional explanatory view showing the connection structure by the cast iron pipe joint, FIG. 10 is a cross-sectional explanatory view showing the manufacturing method of the conventional cast iron pipe joint, FIG. 11 is an enlarged cross-sectional explanatory view showing the manufacturing process of the conventional cast iron pipe joint, FIG. 12 is a sectional explanatory view showing a retaining ring fitting groove of a conventional cast iron pipe joint. 1 …… Cast iron pipe fitting 2 …… Retaining ring fitting groove 2a …… Bottom surface 2b …… Rising surface

Claims (1)

[Claims] 1. A cast iron pipe joint having a retaining ring fitting groove formed therein, wherein an angle between a bottom surface of the retaining ring fitting groove and a rising surface including an intersection of the bottom surface is as-cast. A cast iron pipe joint characterized by being formed at 90 ° or less.