A high-torque carbon steel insulated joint

Abstract

This utility model relates to a high-torque carbon steel insulating joint, belonging to the field of pipeline connection technology. It includes an internal thread insert, an external thread insert, and a PPR insulating plastic body enclosing both. The internal thread insert is made of carbon steel and has an external hexagonal structure and a first torque claw at the bottom. The external thread insert has a second torque claw at the bottom. The first and second torque claws overlap longitudinally and interlock to achieve torque transmission. External threads are located on the external thread insert, and internal threads are located on the internal thread insert. This utility model effectively solves the problems of assembly damage and after-sales failure caused by insufficient torque in traditional plastic-bodied insulating joints by concentrating the torque-bearing structure in the carbon steel internal thread insert and utilizing the interlocking structure between the inserts to transmit the assembly torque of the external thread.

Description

Technical Field

[0001] This utility model relates to the field of high-torque carbon steel insulating joint. Background Technology

[0002] In electric water heaters, to prevent electrochemical corrosion between the inner metal tank and external metal pipes, insulating joints are typically installed at the inlet and outlet to achieve electrical isolation. These insulating joints generally consist of a metal threaded insert and a plastic body. The metal component is encased in plastic using an injection molding process, thus achieving both water connection and electrical insulation. Currently, widely used insulating joints often employ all-brass inserts or partially plastic load-bearing structures and are applied in PPR piping systems.

[0003] In existing technologies, common insulating joint designs often use brass for both the inner and outer thread inserts, with a plastic body providing partial structural support. During assembly, the outer thread end needs to be threaded into an external metal pipe, applying a certain torque. However, due to the limited strength of the plastic body, excessive torque can easily cause the plastic to crack or the insert to loosen, leading to seal failure or connection detachment. Furthermore, in some designs, the outer thread insert alone bears the assembly torque, lacking an effective force transmission path, further exacerbating the risk of structural failure. To ensure strength, it is often necessary to increase the plastic wall thickness or use more metal materials, resulting in increased volume and cost.

[0004] When using torque guns for rapid assembly in automated production lines, traditional structures struggle to stably withstand standard torque values, often resulting in issues such as insert slippage and plastic cracking. This not only impacts production efficiency but also creates safety hazards like water and electrical leaks in the aftermarket. While existing technologies have attempted to improve this by increasing insert length or incorporating anti-rotation structures, they haven't fundamentally solved the problem of an unreasonable torque transmission path. Therefore, significantly improving the torsional resistance of insulated joints, especially the external threaded ends, while ensuring electrical insulation performance has become a major technical challenge urgently needing to be addressed in this field. Utility Model Content

[0005] To solve the above-mentioned technical problems, this utility model provides a high-torque carbon steel insulating joint.

[0006] This utility model provides a high-torque carbon steel insulating joint, which adopts the following technical solution:

[0007] A high-torque carbon steel insulating connector includes an inner thread insert, an outer thread insert, and an insulating plastic body for enclosing the inner thread insert and the outer thread insert. The inner thread insert has two first torque claws fixedly connected to its bottom, and the outer thread insert has two second torque claws fixedly connected to its bottom. The first and second torque claws partially overlap and interlock in the longitudinal direction, so that the torque generated by the outer thread insert during assembly is transmitted to the inner thread insert through the interlocking structure. The inner thread insert has an internal thread, and the outer thread insert has an external thread.

[0008] Preferably, the external wire insert is made of brass.

[0009] Preferably, a plastic connector for pre-connecting the inner and outer wire inserts is provided between them, and the plastic connector is integrally injection molded with the insulating plastic body.

[0010] Preferably, the outer surface of the inner wire insert is provided with a hexagonal structure for cooperating with an assembly tool.

[0011] Preferably, the internal thread is a G3 / 4 internal thread and the external thread is an R1 / 2 external thread.

[0012] Preferably, the insulating plastic body is made of PPR, and the outer peripheral surface of the insulating plastic body is used to connect with an external PPR pipe by hot-melt welding.

[0013] In summary, this utility model has at least one of the following beneficial technical effects:

[0014] 1. By adopting a carbon steel inner wire insert combined with a torque claw engagement structure, the torque during the assembly of the outer wire can be effectively transmitted to the inner wire insert, avoiding the plastic body bearing the main torque, significantly improving the overall torsional strength, and solving the technical problem that traditional insulating joints are prone to assembly damage due to insufficient torque.

[0015] 2. By using a combination of carbon steel inner wire inserts and brass outer wire inserts, the material and processing costs are significantly reduced due to the low cost and high strength of carbon steel and the simple structural design. At the same time, the injection molding accuracy and production efficiency are improved by using small plastic pre-fixed inserts, which is conducive to large-scale manufacturing. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall structure of a high-torque carbon steel insulating joint.

[0017] Figure 2 This is a schematic diagram of the cross-sectional structure of a high-torque carbon steel insulating joint.

[0018] Figure 3 This is an exploded view of a high-torque carbon steel insulated joint after the internal insulating plastic body has been removed.

[0019] Figure 4 This is a schematic diagram of the overall structure of a high-torque carbon steel insulating joint with a plastic body.

[0020] Explanation of reference numerals in the attached drawings: 1. Internal thread insert; 11. Internal thread; 12. External hexagonal structure; 13. First torque claw; 2. External thread insert; 21. Second torque claw; 22. External thread; 3. Insulating plastic body; 4. Small plastic part; 5. Plastic body. Detailed Implementation

[0021] The present invention will be further described in detail below with reference to all the accompanying drawings.

[0022] Example 1

[0023] Reference Figure 1 , Figure 2 and Figure 3 This embodiment discloses a high-torque carbon steel insulating connector, including an internal thread insert 1, an external thread insert 2, and a PPR insulating plastic body 3 enclosing both. The internal thread insert 1 is made of carbon steel and has a G3 / 4 internal thread 11 machined inside for connection with the inner tank of an electric water heater; the internal thread insert 1 has an external hexagonal structure 12 on the outside, which facilitates fastening installation using a torque gun on the production line.

[0024] Reference Figure 1 , Figure 2 and Figure 3 At the bottom of the outer thread insert 2, two radially extending second torque claws 21 are provided; at the bottom of the inner thread insert 1, two corresponding first torque claws 13 are provided. When the two inserts are axially assembled, the first torque claws 13 and the second torque claws 21 partially overlap in the longitudinal direction, forming an interlocking engagement state. Thus, when the outer thread insert 2 is torsion, the torque can be effectively transmitted to the inner thread insert 1 through the engagement structure.

[0025] Reference Figure 1 , Figure 2 and Figure 3 The external threaded insert 2 is made of brass and has an R1 / 2 external thread 22 for connecting to the external water supply metal pipe. The two inserts are pre-connected by two small annular plastic parts 4, which are injection-molded between the two inserts to restrict their relative rotation and ensure positional stability during injection molding. After injection molding, the PPR insulating plastic body 3 is a stepped cylindrical shape with a total height of 47mm and a maximum outer diameter of 30mm. Its outer circumference can be used for heat fusion welding with PPR pipes to achieve a permanent sealed connection.

[0026] The implementation principle of Example 1 is as follows: During assembly, when the external threaded insert 2 is threadedly connected to the external pipe and torque is applied, the torque first acts on the second torque claw 21 at the bottom of the external threaded insert 2. Through engagement with the first torque claw 13 of the internal threaded insert 1, the torque is directly transmitted to the higher-strength carbon steel internal threaded insert 1, rather than relying on the plastic body for support. Because the carbon steel insert has higher shear and torsional strength, the entire joint can withstand higher assembly torque without breakage. Simultaneously, the hexagonal structure on the outside of the internal threaded insert 1 facilitates precise control of the pre-tightening force during the assembly of the water heater inner tank, preventing damage from excessive torque. The pre-fixation of the small plastic part 4 ensures that the relative positions of the two metal inserts remain unchanged in the injection mold, improving product consistency. The PPR plastic body not only provides electrical insulation but also forms an integrated connection with the pipe through heat fusion, eliminating the risk of leakage. This structure achieves a balance between high torque capacity, low-cost manufacturing, and high reliability.

[0027] Example 2

[0028] The difference in this embodiment is that the material of the external thread insert 2 is replaced with stainless steel 304. Although brass has good corrosion resistance and processing performance, it still poses a slight risk of corrosion in areas with hard water or high chlorine content. Using stainless steel 304 for the external thread insert 2 can further improve corrosion resistance, making it particularly suitable for scenarios with high water quality requirements. Its external thread 22 remains R1 / 2 standard, the same as in Embodiment 1, and the connection method remains unchanged. The stainless steel insert needs to undergo surface roughening treatment before injection molding to enhance the bonding force with the PPR plastic. Other structural features, such as the torque claw engagement method, the internal thread carbon steel insert, the hexagonal structure, and the pre-fixation of the small plastic part 4, are consistent with Embodiment 1. After the replacement, the overall torsional resistance remains unchanged, but the long-term reliability is further improved.

[0029] Example 3

[0030] This embodiment discloses a variant structure of a high-torque carbon steel insulating joint, in which the internal thread 11 is replaced with an NPT3 / 4 tapered thread, suitable for North American market standard pipe connections. Other structural features, such as the external thread R1 / 2, torque claw engagement, carbon steel internal thread with hexagonal ribs, and brass external thread, are the same as in Embodiment 1. By changing the thread type, this invention can be adapted to pipe standards in different regions, expanding its application range. This embodiment demonstrates that the core structure has good versatility and scalability.

[0031] Example 4

[0032] Reference Figure 4 The difference in this embodiment is that the outer side of the inner wire insert 1 is wrapped with a layer of plastic body 5. By setting the plastic body 5, it is beneficial to prevent electrochemical corrosion, improve sealing performance, improve stress matching, and enhance the long-term reliability of the overall structure.

[0033] The above are all preferred embodiments of this utility model, and are not intended to limit the scope of protection of this utility model. Therefore, all equivalent changes made to the structure, shape and principle of this utility model should be covered within the scope of protection of this utility model.

Claims

1. A high-torque carbon steel insulating joint, comprising an inner thread insert (1), an outer thread insert (2), and an insulating plastic body (3) for enclosing the inner thread insert (1) and the outer thread insert (2), characterized in that, The bottom of the inner thread insert (1) is fixedly connected to two first torque claws (13), and the bottom of the outer thread insert (2) is fixedly connected to two second torque claws (21). The first torque claws (13) and the second torque claws (21) overlap longitudinally and interlock with each other so that the torque of the outer thread insert (2) can be transmitted to the inner thread insert (1) through the interlocking structure during assembly. The inner thread insert (1) is provided with an internal thread (11), and the outer thread insert (2) is provided with an external thread (22).

2. The high-torque carbon steel insulating joint according to claim 1, characterized in that, The outer wire insert (2) is made of brass.

3. A high-torque carbon steel insulating joint according to claim 1, characterized in that, A small plastic part (4) for pre-connecting the inner wire insert (1) and the outer wire insert (2) is provided between them and is integrally injection molded with the insulating plastic body (3).

4. A high-torque carbon steel insulating joint according to claim 1, characterized in that, The outer surface of the inner wire insert (1) is provided with a hexagonal structure for assembly.

5. A high-torque carbon steel insulating joint according to claim 1, characterized in that, The internal thread (11) is a G3 / 4 internal thread (11), and the external thread insert (2) is provided with an R1 / 2 external thread (22).

6. A high-torque carbon steel insulating joint according to claim 1, characterized in that, The insulating plastic body (3) is made of PPR and is connected to the external pipe by hot melt welding.

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