Socket-end ductile iron jacking pipe and casting method

Abstract

The socket joint ductile iron jacking pipe of the present invention comprises: a pipe body, a socket and a spigot, and also comprises: a push bearing ring, wherein the push bearing ring is arranged on an annular surface perpendicular to the pipe axis at the bottom of the socket; the method for centrifugally casting a socket joint ductile iron jacking pipe of the present invention comprises: manufacturing a sand core corresponding to the socket of the socket joint ductile iron jacking pipe; installing a push bearing ring at a corresponding position of the annular surface perpendicular to the pipe axis at the bottom of the socket joint of the sand core; installing the sand core with the push bearing ring installed on a core frame of a centrifugal casting machine; centrifugally casting the space between the sand core and the pipe mold and the pipe wall of the pipe mold; after centrifugal casting, pulling the socket joint ductile iron jacking pipe out of the pipe mold and removing the sand core in the socket joint ductile iron jacking pipe; the push bearing ring is added in the normal process link of the casting pipe, and has a high molding rate, a stable structure and a low additional cost. The push bearing ring itself is a rigid component and can transfer the axial force of the push process to the pipe body as a whole.

Description

Technical Field

[0001] The invention relates to a socket-and-spigot ductile iron pipe, in particular to a centrifugally cast socket-and-spigot ductile iron jacking pipe and a casting method thereof. Background Art

[0002] The existing trenchless ductile iron jacking pipe is one of the existing metal jacking technologies. It is a product used for trenchless jacking construction, which is improved on the basis of ordinary ductile iron pipes. It is formed by lining the outer wall of ordinary ductile iron pipes with a certain thickness of cement mortar, and welding a jacking flange and a rib plate at the socket part, thereby forming a jacking force transmission structure that uses the socket jacking flange to push the socket end face, thereby realizing the jacking construction of the jacking pipe. This type of ductile iron jacking pipe product adopts traditional slide-in interfaces and rubber rings, which has reliable sealing and simple and convenient installation. However, the jacking flange and rib plate are fixed on the ordinary ductile iron pipe body by welding, which has high welding cost and high welding strength.

[0003] Ordinary ductile iron pipes are not suitable for bearing large jacking forces. At the beginning of the design, more consideration was given to the convenience of interface installation. The structural design of the socket and the spigot is not suitable for jacking operations. Actual tests and engineering installation cases show that even if the ordinary socket-type ductile iron pipe interface bears a small axial jacking force, the spigot will drill into the straight pipe section at the socket end.

[0004] In the application publication number CN106247009A, a metal pipe axial thrust transmission system is proposed, in which an annular flange is set at the contact position between the socket and the spigot. However, according to the existing centrifugal casting process, it is difficult to produce the flange at the axial position of the metal pipe under the action of centrifugal force. By using the water-cooled centrifugal process, a downward slope is set in the direction of the socket. Through the small-diameter centrifugal casting test, although a convex structure can be produced by the static pressure head of the molten iron, its forming rate and product structural stability are not high, far below the normal production and use standards. Therefore, it is urgent to provide a ductile iron pipe jacking product suitable for centrifugal casting technology and a forming method thereof.

[0005] In the prior art, the thrust flange and the rib plate are fixed to the ordinary ductile iron pipe body by welding, which has high welding cost and high welding strength. Even if the ordinary socket-type ductile iron pipe interface is subjected to a small axial thrust force, the spigot will drill into the straight pipe section of the socket end. Summary of the invention

[0006] The invention of the present application aims to overcome the problems existing in the prior art and to provide a socket-end ductile iron jacking pipe and a casting method.

[0007] In order to achieve the invention purpose of this application, the present invention adopts the following technical solutions:

[0008] The invention discloses a ductile iron jacking pipe with a socket joint, which comprises a pipe body, a socket and a spigot, and is characterized in that it also comprises a thrust bearing ring, which is arranged on an annular surface perpendicular to the pipe axis at the bottom of the socket.

[0009] The present invention discloses a ductile iron jacking pipe with a socket joint, wherein: the jacking bearing ring is pre-centrifugally cast and mounted on a sand core, and is sleeved on the corresponding annular surface of the sand core and the bottom of the socket perpendicular to the pipe axis. Through centrifugal casting, the jacking bearing ring and the socket are melt-casted as one or inlaid together, or are formed into one in the form of a combination of melting and inlaying.

[0010] The present invention discloses a ductile iron jacking pipe with a socket joint, wherein: a sand core required for centrifugal casting is provided with a protrusion consistent with the thrust bearing ring at a position corresponding to the annular surface of the bottom of the socket perpendicular to the pipe axis; after centrifugal casting, a groove corresponding to the thrust bearing ring is formed on the annular surface of the bottom of the socket perpendicular to the pipe axis, and the thrust bearing ring is embedded in the ductile iron jacking pipe with a socket joint.

[0011] The present invention discloses a ductile iron jacking pipe with a socket joint, wherein: the inner diameter of the jacking bearing ring is equal to or smaller than the inner diameter of the bare pipe, the outer diameter of the jacking bearing ring is larger than the inner diameter of the bare pipe, and the jacking bearing ring is made of black metal.

[0012] The present invention discloses a ductile iron jacking pipe with a socket joint, wherein the jacking bearing ring is made of cast iron, cast steel or forged steel.

[0013] The present invention discloses a ductile iron jacking pipe with a socket joint, wherein: the outer diameter of the jacking bearing ring is a gradual structure from large to small along the axis of the pipe body from the socket end to the spigot end, and the gradual structure is a trapezoid, an arc, an inclined surface or a combination of the above forms.

[0014] The present invention discloses a ductile iron jacking pipe with a socket joint, wherein the contact surface of the jacking bearing ring that is in direct or indirect contact with the socket is a plane or an annular groove corresponding to the socket.

[0015] The present invention discloses a ductile iron jacking pipe with a socket joint, wherein: the jacking bearing ring is provided with a boss extending toward the axial direction of the pipe body.

[0016] The invention discloses a ductile iron jacking pipe with a socket joint, wherein an annular groove is provided on the circumference of the inner wall of the socket closely attached to the jacking bearing ring, and a gasket is arranged in the annular groove.

[0017] The present invention discloses a ductile iron jacking pipe with a socket joint, wherein a socket guide annular surface is arranged on the inner wall circumference of the socket, and the minimum inner diameter of the guide annular surface is equal to the maximum outer diameter of the socket.

[0018] The centrifugal casting method of the present invention is a method for the socket-shaped ductile iron jacking pipe as claimed in claim 1, wherein:

[0019] (1) Manufacturing a sand core corresponding to the socket of the socket-end ductile iron jacking pipe;

[0020] (2) Install a push bearing ring at the corresponding position of the annular surface perpendicular to the pipe axis at the bottom of the sand core socket;

[0021] (3) Install the sand core with the thrust bearing ring on the core frame of the centrifugal casting machine;

[0022] (4) Centrifugal casting is performed on the space between the sand core and the tube mold and the tube wall of the tube mold;

[0023] (5) After centrifugal casting, pull the socket-shaped ductile iron jacking pipe out of the pipe mold and remove the sand core in the socket-shaped ductile iron jacking pipe.

[0024] The centrifugal casting method of the present invention is a method for the socket-shaped ductile iron jacking pipe as claimed in claim 1, wherein:

[0025] (1) manufacturing a sand core corresponding to the socket of the socket-end ductile iron jacking pipe, wherein the sand core is provided with a protrusion consistent with the jacking bearing ring at a position corresponding to the annular surface perpendicular to the pipe axis at the bottom of the socket;

[0026] (2) Installing the sand core on the core frame of a centrifugal casting machine;

[0027] (3) Centrifugal casting is performed on the space between the sand core and the tube mold and the tube wall of the tube mold;

[0028] (4) After centrifugal casting, the socket-shaped ductile iron jacking pipe is pulled out from the pipe mold, and the sand core in the socket-shaped ductile iron jacking pipe is removed;

[0029] (5) The thrust bearing ring is embedded in the corresponding position of the socket joint ductile iron jacking pipe.

[0030] The beneficial effects of the present invention compared with the prior art are:

[0031] (1) By installing a push bearing ring on the sand core, the problem of adding a structure that is easy to withstand the push force to the top pipe in the centrifugal casting process is solved;

[0032] (2) The push-up bearing structure is provided with a groove body matched with the socket, which is convenient for the socket end to fall into place during the installation process and prevents the cast pipe from being deflected due to the action of non-axial force during the push-up process;

[0033] (3) The thrust bearing structure is arranged on a protrusion close to the center line of the tube body, further preventing the plug from entering the tube;

[0034] (4) A groove may be reserved on the pipe body of the jacking pipe to facilitate the installation of a structure such as a wooden gasket to prevent stress concentration;

[0035] (5) The jacking pipe is melted and casted by hot metal and the jacking bearing ring during the centrifugal operation. The jacking bearing ring is added during the normal process of casting the pipe. It has a high forming rate, a stable structure, and low additional cost. The jacking bearing ring itself is a rigid component and can transfer the axial force of the jacking process to the pipe body as a whole. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a schematic cross-sectional view of the assembly of a socket-end ductile iron jacking pipe of the present invention;

[0037] Figure 2 It is a schematic cross-sectional assembly diagram of another socket-end ductile iron jacking pipe of the present invention;

[0038] Figure 3 for Figure 1 and Figure 2 A side-enlarged schematic diagram of the thrust bearing ring in FIG.

[0039] Figure 4 (a) to (h) are Figure 3 A schematic cross-sectional view of the thrust bearing ring in FIG.

[0040] Figure 5 A cross-sectional schematic diagram of the matching relationship between a pipe mold and a sand core during the centrifugal casting process of a socket-end ductile iron jacking pipe;

[0041] Figure 6 The cross-sectional schematic diagram shows the matching relationship between another pipe mold and the sand core during the centrifugal casting process of the socket-end ductile iron jacking pipe.

[0042] exist Figures 1 to 6 Among them, number 1 is the socket; number 2 is the plug; number 3 is the thrust ring; number 4 is the pipe body; number 5 is the guide surface; number 6 is the annular groove body; number 7 is the boss; number 8 is the sand core; number 9 is the pipe mold. DETAILED DESCRIPTION

[0043] Embodiment 1 of the ductile iron jacking pipe with a socket joint of the present invention

[0044] like Figure 1 As shown, the ductile iron jacking pipe with a socket joint of the present invention comprises: a pipe body 4, a socket 1, a spigot 2 and a thrust bearing ring 3, wherein the thrust bearing ring 3 is arranged on an annular surface perpendicular to the pipe axis at the bottom of the socket, as shown in FIG. Figure 5As shown, the push bearing ring 3 is pre-centrifugal casted and mounted on the sand core 8, and is sleeved at the corresponding position of the sand core 8 and the annular surface of the bottom of the socket perpendicular to the pipe axis. Through centrifugal casting, the push bearing ring 3 and the socket 1 are melted into one or inlaid together or the combination of melting and inlaying is integrated into one. In the centrifugal casting process, the temperature of the injected molten iron determines the final state between the push bearing ring 3 and the socket 1. If the temperature of the molten iron is high, far exceeding the melting point of the push bearing ring 3, the push bearing ring 3 and the socket 1 can be melted into one. If the temperature of the molten iron is lower than the melting point of the push bearing ring 3, the push bearing ring 3 and the socket 1 are inlaid. If the molten iron problem is between the upper and lower ranges of the melting point of the push bearing ring 3, the push bearing ring 3 and the socket 1 are inlaid and melted. The combination of the two forms is integrated. The inner diameter of the push bearing ring 3 is equal to or smaller than the inner diameter of the bare pipe, and the outer diameter of the push bearing ring 3 is larger than the inner diameter of the bare pipe. The push bearing ring 3 is made of black metal, such as cast iron, cast steel, forged steel or alloy steel. Figure 3 and Figure 4 As shown, the outer diameter of the push bearing ring 3 is a gradual structure from large to small along the axis of the pipe body from the socket end to the spigot end, and the gradual structure is a trapezoid, an arc, an inclined surface or a combination of the above forms, such as Figure 4 As shown in (d), the thrust bearing ring 3 is provided with a boss extending toward the axis of the pipe body. The contact surface of the thrust bearing ring 3 that directly or indirectly contacts the socket 2 is a plane or an annular groove corresponding to the socket. A socket guide ring surface 5 is provided on the inner wall circumference of the socket 1, and the minimum inner diameter of the guide ring surface 5 is equal to the maximum outer diameter of the socket 2. A coating is also applied on the inner side of the pipe body 4, the socket 1, the socket 2 and the thrust bearing ring 3.

[0045] Embodiment 2 of the ductile iron jacking pipe with a socket joint of the present invention

[0046] It is basically the same as Example 1, and the same parts are not repeated here, except that:

[0047] like Figure 6 As shown, the sand core 8 required for centrifugal casting is provided with a protrusion 7 consistent with the thrust bearing ring 3 at the corresponding position of the annular surface perpendicular to the pipe axis at the bottom of the socket. After centrifugal casting, the thrust bearing ring 3 is embedded in the ductile iron jacking pipe of the socket joint.

[0048] Embodiment 3 of the ductile iron jacking pipe with a socket joint of the present invention

[0049] It is basically the same as Embodiment 1 and 2, and the same parts are not repeated here, except that:

[0050] like Figure 2 As shown, an annular groove 6 is provided on the circumference of the inner wall of the socket 1 close to the thrust bearing ring 3, and a gasket is installed in the annular groove 6. The gasket can be a wooden gasket, a fiber gasket, and can be a circular gasket or a semicircular detachable gasket.

[0051] One of the methods of centrifugally casting a socket-end ductile iron jacking pipe of the present invention

[0052] like Figure 5 As shown, a method for centrifugally casting a socket-end ductile iron jacking pipe of the present invention comprises:

[0053] (1) manufacturing a sand core 8 corresponding to the socket 1 of the socket-end ductile iron jacking pipe;

[0054] (2) Install a push bearing ring 3 at the corresponding position of the annular surface perpendicular to the pipe axis at the bottom of the socket of the sand core 8;

[0055] (3) Install the sand core 8 with the thrust bearing ring 3 on the core frame of the centrifugal casting machine;

[0056] (4) Centrifugal casting is performed on the space between the sand core 8 and the tube mold 9 and the tube wall of the tube mold 9;

[0057] (5) After centrifugal casting, the socket-shaped ductile iron jacking pipe is pulled out from the pipe mold 9, and the sand core 8 in the socket-shaped ductile iron jacking pipe is removed.

[0058] Method 2 of centrifugally casting a ductile iron jacking pipe with a socket end according to the present invention

[0059] like Figure 6 As shown, another method for centrifugally casting a socket-end ductile iron jacking pipe of the present invention comprises:

[0060] (1) A sand core 8 is manufactured corresponding to the socket 1 of the socket-jointed ductile iron jacking pipe, and a protrusion 7 corresponding to the thrust bearing ring 3 is provided at the bottom of the socket corresponding to the annular surface perpendicular to the pipe axis of the sand core 8;

[0061] (2) Install the sand core 8 on the core frame of the centrifugal casting machine;

[0062] (3) Centrifugal casting is performed on the space between the sand core 8 and the tube mold 9 and the tube wall of the tube mold 9;

[0063] (4) After centrifugal casting, the socket-shaped ductile iron jacking pipe is pulled out from the pipe mold 9, and the sand core 8 in the socket-shaped ductile iron jacking pipe is removed;

[0064] (5) The thrust bearing ring 3 is embedded in the corresponding position of the ductile iron jacking pipe with the socket joint.

[0065] The above is a schematic description of the present invention and its implementation methods, which is not restrictive. The drawings show only one implementation method of the present invention, and the actual structure is not limited thereto. Therefore, if a person skilled in the art is inspired by it and creatively designs methods and embodiments similar to the technical solution without departing from the purpose of the present invention, they should all fall within the scope of protection of this patent.

Claims

1. A socket-end ductile iron jacking pipe, comprising: A pipe body (4), a socket (1), a plug (2) and a push bearing ring (3), wherein the push bearing ring (3) is arranged on an annular surface at the bottom of the socket (1) perpendicular to the pipe axis, and is characterized in that: the push bearing ring (3) is pre-installed on a sand core (8) required for centrifugal casting, and is sleeved on the sand core (8) and the corresponding annular surface at the bottom of the socket (1) perpendicular to the pipe axis. Through centrifugal casting, the push bearing ring (3) and the socket (1) are fused into one or inlaid together or in a combination of fusion and inlaying to form a whole.

2. A socket-end ductile iron jacking pipe, comprising: A pipe body (4), a socket (1), a spigot (2) and a thrust bearing ring (3), wherein the thrust bearing ring (3) is arranged on an annular surface at the bottom of the socket (1) perpendicular to the pipe axis, and is characterized in that a sand core (8) required for centrifugal casting is provided with a protrusion (7) consistent with the thrust bearing ring (3) at a position corresponding to the annular surface at the bottom of the socket perpendicular to the pipe axis, and after centrifugal casting, a groove corresponding to the thrust bearing ring (3) is formed on the annular surface at the bottom of the socket perpendicular to the pipe axis, and the thrust bearing ring (3) is embedded in the ductile iron top pipe groove of the socket.

3. The socket-end ductile iron jacking pipe according to claim 1 or 2, characterized in that: The inner diameter of the thrust bearing ring (3) is equal to or smaller than the inner diameter of the bare pipe, the outer diameter of the thrust bearing ring (3) is larger than the inner diameter of the bare pipe, and the thrust bearing ring (3) is made of black metal.

4. The socket-end ductile iron jacking pipe according to claim 3, characterized in that: The thrust bearing ring (3) is made of cast iron, cast steel or forged steel.

5. The socket-end ductile iron jacking pipe according to claim 3, characterized in that: The outer diameter of the thrust bearing ring (3) is a gradual structure from large to small along the axis of the pipe body from the socket end to the spigot end, and the gradual structure is a trapezoid, an arc, an inclined surface or a combination of the above forms.

6. The bell-and-spigot ductile iron jacking pipe according to claim 3, characterized in that: The contact surface of the thrust bearing ring (3) that is in direct or indirect contact with the socket (2) is a plane or an annular groove corresponding to the socket end.

7. The bell-and-spigot ductile iron jacking pipe according to claim 3, characterized in that: The thrust bearing ring (3) is provided with a boss extending in the direction of the axis of the tube body.

8. The socket-end ductile iron jacking pipe according to any one of claims 4 to 7, characterized in that: An annular groove (6) is provided on the circumference of the inner wall of the socket (1) which is closely attached to the thrust bearing ring (3), and a gasket is arranged in the annular groove (6).

9. The socket-end ductile iron jacking pipe according to claim 8, characterized in that: A socket guide annular surface (5) is provided on the inner wall circumference of the socket (1), and the minimum inner diameter of the guide annular surface (5) is equal to the maximum outer diameter of the socket (2).

10. A method for centrifugally casting the socket-end ductile iron jacking pipe according to claim 1, characterized in that: (1) manufacturing a sand core (8) corresponding to the socket (1) of the socket-end ductile iron jacking pipe; (2) Install a push bearing ring (3) at a position corresponding to the annular surface perpendicular to the pipe axis at the bottom of the socket of the sand core (8); (3) Installing the sand core (8) of the thrust bearing ring (3) on the core frame of the centrifugal casting machine; (4) centrifugally casting the space between the sand core (8) and the tube mold (9) and the tube wall of the tube mold (9); (5) After centrifugal casting, the socket-shaped ductile iron jacking pipe is pulled out from the pipe mold (9), and the sand core (8) in the socket-shaped ductile iron jacking pipe is removed.

11. A method for centrifugally casting the socket-end ductile iron jacking pipe as claimed in claim 2, characterized in that: (1) manufacturing a sand core (8) corresponding to the socket (1) of the socket-shaped ductile iron jacking pipe, wherein the sand core (8) is provided with a protrusion (7) corresponding to the jacking bearing ring (3) at a position corresponding to the annular surface at the bottom of the socket perpendicular to the pipe axis; (2) installing the sand core (8) on the core frame of a centrifugal casting machine; (3) centrifugally casting the space between the sand core (8) and the tube mold (9) and the tube wall of the tube mold (9); (4) After centrifugal casting, the socket-shaped ductile iron jacking pipe is pulled out from the pipe mold (9), and the sand core (8) in the socket-shaped ductile iron jacking pipe is removed; (5) The thrust bearing ring (3) is embedded in the corresponding position of the socket-end ductile iron jacking pipe.

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