JP7187296B2 - conversion fitting - Google Patents

Description

TECHNICAL FIELD The present invention relates to a conversion joint that connects a metal pipe member and a synthetic resin pipe member.

A conversion joint for connecting a metal pipe member and a synthetic resin pipe member is made of metal and includes a tubular joint body having a resin pipe connection portion at one end and a resin pipe connection portion at one end. and a ring that is fitted onto one end of the resin pipe and presses the inner peripheral surface of the one end of the resin pipe against the outer peripheral surface of the resin pipe connecting portion. . In such a conversion joint, even if the resin pipe shrinks due to a change in temperature or the like, it is required to appropriately prevent the ring from detaching and reliably prevent the resin pipe from coming off.

For example, Japanese Patent Laying-Open No. 2015-166601 (Patent Document 1) discloses such a conversion joint. The conversion joint disclosed in Patent Document 1 includes a joint body made of metal having a resin pipe connecting portion at one end, a resin pipe having one end fitted to the resin pipe connecting portion, and one of the resin pipes. A ring that is fitted on the end portion and presses the inner peripheral surface of one end of the resin pipe against the outer peripheral surface of the resin pipe connection portion, and an annular ring that is formed on the inner peripheral surface of the ring and extends in the circumferential direction. a concave portion, an annular first convex portion formed on the outer peripheral surface of the resin pipe connecting portion at a position facing the concave portion and extending in the circumferential direction, and a ring-shaped first convex portion on the outer peripheral surface of the resin pipe connecting portion on the front side of the first convex portion; An annular second convex portion is formed and extends in the circumferential direction, and by making the first convex portion higher than the second convex portion, the resin is It is characterized by bending the pipe in the radial direction.

JP 2015-166601 A

As disclosed in FIG. 4 of Patent Document 1 and its description, this conversion joint is assembled according to the following assembly procedure. Note that such an assembly procedure is common for a conversion joint that connects a metal pipe member and a synthetic resin pipe member. One end of the resin pipe is fitted onto the resin pipe connecting portion of the joint body. Specifically, the resin pipe is pushed in along the tapered surface of the introduction portion of the resin pipe connecting portion, and the resin pipe connecting portion is forcibly inserted into the resin pipe. That is, the resin pipe is pushed in while expanding the diameter of one end of the resin pipe by the resin pipe connecting portion. At this time, a restoring force is generated at one end of the resin pipe, which has been expanded in diameter due to the forced insertion of the resin pipe connection, to return to the original diameter. do.

In this manner, the introduction portion of the resin pipe connecting portion is provided with a tapered surface, and the resin pipe is pushed in while expanding its diameter along the tapered surface. As shown in FIG. 3 of Patent Document 1, D is the outer diameter of the resin pipe connection portion other than the convex portion, which is the diameter of the flat surface at the end position of the tapered surface at the resin pipe connection portion (the diameter at the start position of this flat surface and other than the convex portion). connected). Assuming that the inner diameter of the resin pipe is d, the diameter expansion rate of the resin pipe is defined as D/d.

However, as a result of a tensile test to confirm that problems such as the joint coming off before the resin pipe yields when this diameter expansion ratio increases, strain concentrates at the end position of the taper surface and It is possible that the resin tube will break before the rest of the resin tube yields. In particular, the smaller the nominal diameter, the larger the diameter expansion ratio. If cast iron is used instead of bronze (although the material is not limited in the present invention) for the metal joint body having the resin pipe connection part, the pipe thickness will increase. As the diameter increases, the diameter expansion rate increases because the inner diameter must be secured. When the diameter expansion rate is increased in this way, strain is concentrated at the end position of the tapered surface, and the possibility of breakage of the resin pipe increases as described above. In order to avoid such breakage, heat treatment may be performed to relieve the stress of the resin pipe. productivity will decrease.

The present invention was developed in view of the above-mentioned problems, and its object is to provide a conversion joint for connecting a metal pipe member and a synthetic resin pipe member with a large diameter expansion rate. To provide a conversion joint capable of suppressing breakage of a resin pipe including the end position of a tapered surface even if there is.

In order to achieve the above object, the conversion joint according to the present invention takes the following technical measures.
That is, the conversion joint according to the present invention is a conversion joint for connecting a metal pipe member and a synthetic resin pipe member, and is formed of metal and has a cylindrical shape having a resin pipe connection portion at one end. a joint main body, a resin pipe having one end fitted onto the resin pipe connection portion, and a resin pipe fitted onto the one end of the resin pipe so that the inner peripheral surface of the one end of the resin pipe is attached to the resin pipe. and a ring pressed against the outer peripheral surface of the connecting portion, and the resin pipe connecting portion has an inclined surface where the outer diameter of the resin pipe connecting portion gradually increases from the open side in a cross section including the axial center of the pipe member, and the inclined surface. and a flat surface following the surface, and a plurality of annular projections are formed on the outer peripheral surface of the flat surface, and from the starting point of the flat surface to the starting point of the first annular projection, which is the first annular projection. is provided with a first flat portion having a predetermined axial length, and in a cross section including the axial center of the tubular member, the extension of the inclined surface does not intersect the first annular projection.

Preferably, the tube outer diameter D1 at the starting point of the inclined surface, the tube outer diameter D2 at the starting point of the flat surface, the axial length L1 of the inclined surface, and H1=(D2−D1)/2, where H1/ L1 can be configured to be less than or equal to 0.38.
More preferably, the pipe outer diameter D1 at the starting point of the inclined surface, the pipe outer diameter D2 at the starting point of the flat surface, the axial length L1 of the inclined surface, H1=(D2−D1)/2, the As the axial length L2 of one flat portion, H1/(L1+L2) can be configured to be 0.27 or less.

More preferably, the axial length L1 of the inclined surface and the axial length L2 of the first flat portion can be configured such that L2/L1 is 0.41 or less.
More preferably, the tube outer diameter D2 at the starting point of the flat surface, the axial length L1 of the inclined surface, and the tube outer diameter D3 including the first annular projection are: ((D3-D2)/2)/ L1 can be configured to be less than or equal to 0.05.

According to the present invention, in a conversion joint that connects a metal pipe member and a synthetic resin pipe member, breakage of the resin pipe including the end position of the tapered surface is suppressed even with a large diameter expansion ratio. It is possible to provide a conversion joint that can

It is a side view which shows the external shape of the conversion joint 100 which concerns on embodiment of this invention. 2 is a cross-sectional view of the conversion joint of FIG. 1; FIG. It is sectional drawing of (A) joint main body of the conversion joint of FIG. 2, (B) ring, and (C) resin pipe. 4 is a partially enlarged cross-sectional view (hatching omitted) of region 4 in FIG. 3(A); FIG.

Hereinafter, a conversion joint 100 according to an embodiment of the present invention will be described in detail based on the drawings. This conversion joint 100 is a conversion joint that connects a metal pipe member and a synthetic resin pipe member. It is used to connect a pipe made of synthetic resin such as polyethylene to a pipe member. In the following description of the joint main body 110 that constitutes the conversion joint 100, the resin pipe 120 side in the axial direction may be referred to as the open side or front side, and the opposite side may be referred to as the back side.

The conversion joint 100 will be described in detail with reference to FIG. 1, which is a side view showing the external shape of the conversion joint 100, FIG. The conversion joint 100 is made of metal, and has a cylindrical joint body 110 having a resin pipe connection portion 112 at one end, a resin pipe 120 having one end fitted onto the resin pipe connection portion 112, and a resin pipe. A ring 130 is fitted around one end of the resin pipe 120 to press the inner peripheral surface of the one end of the resin pipe 120 against the outer peripheral surface of the resin pipe connecting portion 112 . More specifically, in a cross section including the axial center of the pipe member, the resin pipe connection portion 112 has an inclined surface 112A in which the outer diameter of the resin pipe connection portion 112 gradually increases from the open side and a flat surface 112B continuing to the inclined surface 112A. , and a plurality of annular projections 112C are formed on the outer peripheral surface of the flat surface 112B. A first flat portion 112D having a predetermined axial length is provided from the starting point of the flat surface 112B to the starting point of the first annular projection 112C1, which is the first annular projection 112C, as shown in FIG. , the extension of the inclined surface 112A does not intersect the first annular protrusion 112C1 in a cross section including the axial center of the pipe member.

Here, FIGS. 1 and 2 omit the other end of the cylindrical joint body 110 having the resin pipe connection portion 112 at one end, but for example, the omitted portion may be replaced with a union nut. It may be a union-type conversion joint in which is formed, or may have another configuration. As an example of another configuration, a valve (gate valve) is included in the metal pipe member to which the conversion joint 100 is connected, and the joint main body 110 corresponds to joint portions at both ends of the valve.
The conversion joint 100 shown in FIG. 4 and having the feature that the extension of the inclined surface 112A does not intersect the first annular protrusion 112C1 will be described in more detail.

<Coupling body>
As shown in FIGS. 1 to 4, the joint body 110 of the conversion joint 100 is a cylindrical body formed of metal such as, but not limited to, cast iron and copper alloy (bronze). A resin pipe connecting portion 112 is formed in the portion.
The resin pipe connection portion 112 is formed in a short cylindrical shape, and a stepped portion 114 is formed in a portion of the joint main body 110 corresponding to the boundary with the resin pipe connection portion 112 . In addition, an inclined surface 112A is formed at the tip portion of the resin pipe connection portion 112 so that the outer diameter of the resin pipe connection portion 112 gradually increases from the open side to the inner side. 112 A of this inclined surface is formed so that the pipe end of the resin pipe 120 can be easily received, and generation|occurrence|production of stress concentration in 112 A of inclined surfaces can be suppressed. Also, the tip portion of the inclined surface 112A is chamfered to form a curved shape.

In the resin pipe connecting portion 112, a plurality of annular projections 112C are formed on the outer peripheral surface of the flat surface 112B that continues to the inclined surface 112A. Conversion joint 100 according to the present embodiment has four annular projections 112C arranged in the axial direction (the number of annular projections 112C is not limited to four). These annular projections 112C are the first annular projection 112C1, which is the first annular projection 112C from the starting point of the flat surface 112B, to the fourth annular projection 112C4, which is the fourth annular projection 112C. Each of these annular projections 112C has a substantially trapezoidal cross-section, and the joint portion with the flat surface 112B is chamfered to form a curved surface shape. Although not limited, the inclination angle α on the opening side of the annular projection 112C is set to 45°, and the inclination angle β on the back side is set larger than the inclination angle α as is noticeable in the fourth annular projection 112C4. It is These annular projections 112</b>C make it easier to lock the resin pipe 120 and prevent the resin pipe 120 from coming off the resin pipe connecting portion 112 .

Moreover, although not limited, the outer diameter (protrusion height) of the four annular projections 112C is set so as to gradually increase from the open side, so that the annular projection 112C is formed on the inner peripheral surface of the resin pipe 120. bites into the resin pipe 120, the resin pipe 120 is reliably prevented from coming off from the resin pipe connecting portion 112. - 特許庁
As shown in FIG. 4, the outer diameter (protrusion height) of the first annular protrusion 112C1 and the length L2 of the first flat portion 112D have the slope of the inclined surface 112A in a cross section including the axial center of the pipe member. A basic condition is established that the extension line does not cross the first annular projection 112C1.

If another viewpoint is added to this basic condition, the following numerical conditions are established.
Referring to FIG. 4, tube outer diameter D1 at the starting point of inclined surface 112A, tube outer diameter D2 at the starting point of flat surface 112B, axial length L1 of inclined surface 112A, H1=(D2−D1)/2 , the axial length L2 of the first flat portion 112D and the tube outer diameter D3 including the first annular projection 112C1,
First numerical condition: H1/L1≤0.38
Second numerical condition: H1/(L1+L2)≤0.27
Third numerical condition: L2/L1≤0.41
Fourth numerical condition: ((D3-D2)/2)/L1≤0.05
is. Here, ((D3-D2)/2) is the projection height of the first annular projection 112C1.

In this way, the extension of the inclined surface 112A does not intersect the first annular protrusion 112C1, and the joint body 110 including the resin pipe connection portion 112 that satisfies the first to fourth numerical conditions described above is included. The configured conversion joint 100 exhibits the performance described later. Here, the conversion joint 100 according to the present invention does not need to satisfy all of the above-described first to fourth numerical conditions, nor does it need to satisfy at least one numerical condition. The basic condition of not intersecting the 1-ring projection 112C1 must always be satisfied.
Note that the outer peripheral portion of the resin pipe connection portion 112, that is, the inclined surface 112A, the flat surface 112B, the plurality of annular projections 112C, and the like, are formed by, for example, casting when the material is cast iron. It can be formed by cutting from.

<Ring/resin pipe>
As shown in FIGS. 1 to 4, one end of a resin pipe 120 is fitted to the resin pipe connection portion 112 of the conversion joint 100, and the resin pipe connection portion 112 and the resin pipe 120 are fitted together. A ring 130 is fitted over the portion. The resin pipe 120 is a pipe member made of synthetic resin such as polyethylene, and the inner diameter of the resin pipe 120 is set equal to or smaller than the outer diameter of the resin pipe connecting portion 112 of the joint main body 110. When fitting one end of the resin pipe 120 to the resin pipe connecting portion 112 , the resin pipe connecting portion 112 is forced into the resin pipe 120 .

The ring 130 is a member that tightens one end of the resin pipe 120 from the outside and presses the inner peripheral surface of the resin pipe 120 against the outer peripheral surface of the resin pipe connection portion 112 to prevent the resin pipe 120 from coming off. The ring 130 is made of a metal such as stainless steel, copper, or cast iron and has a short cylindrical shape. include. The expanded diameter portion 132 is formed so that the inner diameter increases toward the inner side.

The inner diameter of the ring 130 is set to be smaller than the outer diameter of one end of the resin pipe 120 fitted on the resin pipe connecting portion 112 . , one end of the resin pipe 120 is forcibly inserted into the ring 130 . When the ring 130 is fitted onto one end of the resin pipe 120 , the ring 130 comes into contact with the stepped portion 114 of the joint body 110 .

By forming the enlarged diameter portion 132 in the ring 130 in this manner, the ring 130 is fitted to the fitting portion between the resin pipe connection portion 112 and the resin pipe 120, and the inner peripheral surface of the ring 130 and the resin pipe 120 are fitted together. When the outer peripheral surface of the one end portion is in a crimped state, the outer diameter of the one end portion of the resin pipe 120 increases along the inner diameter of the enlarged diameter portion 132 toward the inner side. Therefore, the inner peripheral surface of the one end of the resin pipe 120 serves as a stopper, and the rearward movement of the ring 130 with respect to the resin pipe 120 is restricted.

<Assembly procedure>
A procedure for assembling the conversion joint 100 according to the present embodiment will be described below. That is, a procedure is performed in which one end of the resin pipe 120 is fitted onto the resin pipe connection portion 112 of the joint body 110 and the ring 130 is fitted onto the fitting portion between the resin pipe 120 and the resin pipe connection portion 112 . explain in detail.
One end of the resin pipe 120 is fitted onto the resin pipe connecting portion 112 of the joint body 110 . Specifically, the resin pipe 120 is pushed in along the inclined surface 112A of the resin pipe connection portion 112, and the resin pipe connection portion 112 is forcibly inserted into the resin pipe 120 as it is. That is, resin pipe 120 is pushed into joint main body 110 while one end of resin pipe 120 is expanded in diameter by resin pipe connecting portion 112 . At this time, a restoring force is generated at one end of the resin pipe 120, which has been expanded in diameter due to the forced insertion of the resin pipe connecting portion 112, to return to the original diameter. adhere to.

After that, the ring 130 is fitted onto one end of the resin pipe 120 , that is, the fitting portion between the resin pipe 120 and the resin pipe connecting portion 112 . Specifically, one end of the resin pipe 120 connected to the resin pipe connecting portion 112 is inserted from the inner side of the ring 130 . Then, one end of the resin pipe 120 is forcibly inserted into the ring 130 as it is. That is, while pressing one end of the resin pipe 120 from the outside by the ring 130 , the inner end surface of the ring 130 is positioned at the inner end surface of the resin pipe 120 and the inner end surface of the ring 130 is positioned at the inner end surface of the joint main body 110 . The ring 130 is pushed in until it comes to a position where it contacts the stepped portion 114 .

When the ring 130 is externally fitted to the fitting portion between the resin pipe 120 and the resin pipe connecting portion 112, and the inner peripheral surface of the resin pipe 120 and the outer peripheral surface of the resin pipe connecting portion 112 are crimped, the resin pipe 120 is The annular projection 112C bites into the inner peripheral surface. As a result, the water stopping performance between the resin pipe 120 and the resin pipe connecting portion 112 is ensured, and the resin pipe 120 is prevented from coming off from the resin pipe connecting portion 112 . Further, the inner peripheral surface of the ring 130 and the outer peripheral surface of the one end of the resin pipe 120 are in a crimped state, and the outer diameter of the one end of the resin pipe 120 extends along the inner diameter of the enlarged diameter portion 132 to the far side. , and the movement of the ring 130 is restricted.
In this way, since the structure is simple, in which the resin pipe 120 and the ring 130 are forcibly inserted into the resin pipe connecting portion 112 of the joint body 110, there is no need to caulk the ring 130, and the like can be easily manufactured. be able to.

<Performance evaluation test>
The conversion joint 100 according to the present embodiment assembled by the structure and assembly procedure described above was subjected to a high-speed tensile test as follows to evaluate performance. In addition, this high-speed tensile test is a tensile test to confirm the safety against high-speed tension of the pipe because it is assumed that the ground deformation due to the earthquake will occur instantaneously and the pipe will be pulled at a rapid speed. This test confirms that the joint (the resin pipe 120 fitted to the resin pipe connection portion 112) has a strength equal to or greater than that of the resin pipe 120 when tension is applied to the conversion joint. It is a test for More specifically, one end of the conversion fitting 100 is fixed to a reaction wall and the other end is connected to a hydraulic servo actuator to force a constant velocity (approximately 100 times faster than a typical pull-out prevention performance test). By applying displacement and measuring the relationship between the generated load and displacement, the strength of the conversion joint was investigated and its performance was evaluated.

The performance evaluation of the conversion joint 100 using this high-speed tensile test is performed before the resin pipe 120 in the portion externally fitted to the resin pipe connection portion 112 is pulled out or broken (abnormality occurs in the conversion joint 100). , when the resin pipe 120 other than the portion externally fitted to the resin pipe connection portion 112 yields, it is determined to be acceptable (it is determined that this conversion joint 100 has a greater strength than the resin pipe 120 itself), and the resin pipe connection portion 112 Before the resin pipe 120 other than the portion externally fitted to yields, the resin pipe 120 externally fitted to the resin pipe connecting portion 112 is pulled out or broken (abnormality occurs in the conversion joint 100) was determined to be unacceptable (determined that this conversion joint 100 does not have a strength greater than that of the resin pipe 120 itself). The inner diameter d (nominal diameter) of the resin pipe 120 is approximately 50 mm to 200 mm.

Satisfies only the basic condition that the extension line of the inclined surface 112A does not intersect the first annular projection 112C1, or satisfies at least one of the first to fourth numerical conditions. Although the conversion joint 100 that was used was acceptable even when the strain of the resin pipe 120 exceeded 13% and even exceeded 20%, when these conditions were not satisfied, the strain of the resin pipe 120 was 9% and was unsatisfactory. It passed. Regarding this failure, if the above conditions are not satisfied, the vicinity of the boundary between the inclined surface 112A and the flat surface 112B in the resin pipe connection portion 112 (the end of the inclined surface 112A (tapered surface) which is the Y portion shown in FIG. 4) position), the stress was concentrated and a large strain was generated, and the resin pipe 120 was broken at that portion. On the other hand, when the above-mentioned conditions are satisfied, at the end position of the inclined surface 112A, which is the Y portion shown in FIG. was not broken.

As described above, according to the conversion joint according to the present embodiment, the end of the tapered surface is It is possible to suppress breakage of the resin pipe including the position.
It should be noted that the embodiments disclosed this time should be considered as examples in all respects and not restrictive. The scope of the present invention is indicated by the scope of the claims rather than the above description, and is intended to include all modifications within the meaning and range of equivalents of the scope of the claims.

INDUSTRIAL APPLICABILITY The present invention is a conversion joint that connects a metal pipe member and a synthetic resin pipe member, and is preferable for a conversion joint that has a simple structure and can be easily manufactured without the need for crimping work, etc., and has a large diameter expansion rate. Even if there is, it is particularly preferable in that it is possible to suppress breakage of the resin pipe including the end position of the tapered surface.

REFERENCE SIGNS LIST 100 conversion joint 110 joint main body 112 resin pipe connecting portion 112A inclined surface 112B flat surface 112C annular protrusion 112D flat portion 114 stepped portion 120 resin pipe 130 ring 132 enlarged diameter portion 134 same diameter portion

Claims (5)

A conversion joint that connects a metal pipe member and a synthetic resin pipe member without using a screwing member ,
a cylindrical joint body made of metal and having a resin pipe connecting portion at one end;
a resin pipe having one end fitted onto the resin pipe connecting portion;
a ring fitted on the one end of the resin pipe to press the inner peripheral surface of the one end of the resin pipe against the outer peripheral surface of the resin pipe connecting portion;
The resin pipe connecting portion includes, in a cross section including the axial center of the pipe member, an inclined surface in which the outer diameter of the resin pipe connecting portion gradually increases from the open side and a flat surface continuing to the inclined surface,
A plurality of annular protrusions are formed on the outer peripheral surface of the flat surface,
A first flat portion having a predetermined axial length is provided from the starting point of the flat surface to the starting point of the first annular projection, which is the first annular projection,
The first flat portion has a flat shape without a concave portion,
In a cross section including the axial center of the tubular member, an extension line of the inclined surface does not intersect the first annular projection,
0<((D3-D2)/2)/L1≤ where D2 is the tube outer diameter at the starting point of the flat surface, L1 is the axial length of the inclined surface, and D3 is the tube outer diameter including the first annular projection. A conversion joint characterized by 0.05 . Assuming that the pipe outer diameter D1 at the starting point of the inclined surface, the pipe outer diameter D2 at the starting point of the flat surface, the axial length L1 of the inclined surface, and H1 = (D2-D1)/2,
A conversion joint according to claim 1, characterized in that H1/L1 is 0.38 or less. Pipe outer diameter D1 at the starting point of the inclined surface, pipe outer diameter D2 at the starting point of the flat surface, axial length L1 of the inclined surface, H1=(D2−D1)/2, the first flat portion As the axial length L2,
A conversion joint according to claim 1, characterized in that H1/(L1+L2) is 0.27 or less. As the axial length L1 of the inclined surface and the axial length L2 of the first flat portion,
A conversion joint according to claim 1, characterized in that L2/L1 is 0.41 or less. The inner surface of the ring is composed only of the same diameter portion and the enlarged diameter portion,
The inner diameter of the ring is set to be smaller than the outer diameter of one end of the resin pipe in a state of being fitted onto the resin pipe connecting portion. One end of the resin pipe is forcibly inserted into the ring, and when the ring is fitted onto the one end of the resin pipe, the ring comes into contact with the stepped portion of the joint body. The conversion joint according to any one of claims 1 to 4 .

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