Layered thermoplastic prefabricated large-specification electric connector plug and electric connector

Abstract

The utility model discloses a layered thermoplastic prefabricated large-specification electric connector plug and an electric connector, and belongs to the technical field of thermoplastic electric connectors. The utility model aims to solve the problems of large impact force, easy displacement of a wire, cooling deformation, generation of air holes and the like when a large-specification electric connector plug is subjected to one-time thermoplastic molding. The plug comprises a pin assembly, a wire bundle, a thermoplastic inner layer and an outer layer. And a positioning meshing structure is arranged between the thermoplastic inner layer and the thermoplastic outer layer. According to the utility model, the plug main body is divided into the inner part and the outer part, so that the single injection molding volume and thickness are reduced, the injection molding impact force is reduced, and the problems of wire displacement, air holes, cold shrinkage deformation and the like are avoided. The inner layer and the outer layer can be made of different materials according to requirements, and torsion resistance, wear resistance and crack resistance of the plug are enhanced. The injection mold has the advantages of high injection molding efficiency, high yield, uniform stress distribution, high cooling efficiency, excellent mechanical strength, good insulation performance, good heat dissipation performance and the like. The device is simple in overall structure, stable in performance, high in reliability and particularly suitable for large-current transmission requirements.

Description

TECHNICAL FIELD

[0001] The utility model relates to thermoplastic electric connector technical field especially relates to a layered thermoplastic prefabricated large specification electric connector plug and contain the electric connector of this plug. BACKGROUND

[0002] In power transmission and distribution systems, large specification electric connector plugs play an important role, and their performance directly affects the efficiency of power transmission, as well as the stability and reliability of the system. Currently, large specification electric connector plugs are mostly produced using in-mold one-shot injection molding process. This process uses an injection molding machine to inject molten plastic into a mold at a set temperature and pressure. The plastic tightly covers the structure components such as the pins, insulating supports, and wire connection ends of the plug in different thicknesses according to the shape of the mold, forming the external insulation of the plug. After the plastic cools and sets, the finished plug is obtained. However, for large specification electric connector plugs, this seemingly efficient and convenient one-shot thermoplastic molding process has many problems:

[0003] 1. Risk of wire displacement or even falling off: During the thermoplastic injection stage, due to the large volume of the mold cavity of the large specification electric connector plug, the large amount of injection, the long flow distance of the plastic, and the large flow resistance, the injection pressure needs to be increased to overcome the flow resistance, ensure that the plastic fills the mold fully and uniformly, and avoid underfilling or air bubbles. At the same time, to ensure that the material completely fills the mold before cooling, and to ensure the molding quality and production efficiency, the injection speed needs to be increased. However, increasing the injection pressure and speed will increase the impact force of the thermoplastic on the internal wire harness of the plug, which can easily cause the wires of the plug wire harness to shift or deform. When the impact force is too large, it may even cause the wires to loosen and fall off at the connection site with the wire connection end, especially when the wires are thick, numerous, and in a tight space, the risk is more significant. In addition, the shrinkage stress generated by the cooling and shrinkage of the thermoplastic material will further increase the risk of wire displacement and connection site loosening at the wire connection end.

[0004] Secondly, the deformation and internal porosity problem after cooling: since the plug needs to bear a large current, the contact (pin, etc.) and the configured wire are relatively thick, which requires the thermoplastic wrapped plastic body to have sufficient thickness to meet the insulation performance standard. However, the thickened plastic body has different cooling speeds in different parts during the cooling process. For example, the surface of the plastic body cools faster, while the inside cools slower; the first injection-molded part has already cooled and solidified, while the later injection-molded part is still cold. This uneven cooling shrinkage phenomenon is easy to deform the plastic body. And, air is easy to be rolled into the thermoplastic material during the injection process; and, air is easy to be rolled into the thermoplastic material during the injection process, and the thermoplastic material will undergo a chemical reaction during the solidification process to generate gas. Since the thickened plastic body is not conducive to the discharge of gas, internal porosity is easy to form. These pores or incomplete solidification parts will damage the structural integrity of the plastic body, leading to a decrease in material performance, and then affecting the mechanical strength and insulation performance of the plug. The deformation after cooling may cause the size of the connector to be unstable, affecting the plug-in adaptability; and internal structural defects such as porosity may reduce the insulation performance and mechanical strength. In addition, surface flaws or unevenness will affect the overall appearance and reliability of the product. Practical new content

[0005] In view of the problems existing in the prior art, the utility model provides a small impact, structural stability, suitable for thermoplastic forming large specification large current electric connector plug, electric connector.

[0006] The above purpose of the utility model is realized by the following technical scheme:

[0007] A layered thermoplastic prefabricated large specification electric connector plug, comprising a pin assembly, a wire bundle fixedly connected with the pin assembly, an injection-molded inner layer wrapped outside the pin assembly and the wire bundle and formed by primary thermoplastic molding, and an outer layer wrapped outside the injection-molded inner layer and formed by secondary thermoplastic molding; a positioning engagement structure is arranged between the injection-molded outer layer and the injection-molded inner layer to limit the relative rotation and axial movement therebetween, improve the torsional strength of the plug and the overall structural stability.

[0008] The positioning engagement structure comprises a positioning recess provided on the outer circumferential surface of the injection-molded inner layer and a positioning protrusion provided on the inner circumferential surface of the injection-molded outer layer and adapted to be engaged with the positioning recess; the positioning protrusion and the positioning recess are engaged with each other to prevent the relative movement between the outer layer and the inner layer, realize the anti-rotation and axial movement positioning of the two.

[0009] The pin assembly comprises a pin, a pin seat and a pin shell; the pin is fixedly connected to the pin seat; the pin seat is fixed in the pin shell, and the inner circumferential surface of the pin shell is provided with a convex ring which is pressed against the end face of the pin seat to limit the axial movement thereof.

[0010] The needle shell end outer peripheral surface is provided with an outer convex ring, the outer convex ring is clamped in the injection inner layer end, and axial movement of the two is prevented, the combination of the pin assembly and the inner layer is improved, and the inner layer can guarantee sufficient strength under the condition of thickness reduction.

[0011] The needle shell inner peripheral surface is provided with an axial protrusion (1-3-3), the needle seat outer peripheral surface is provided with an axial groove A at the corresponding position, the inner layer is provided with an axial groove B at the corresponding position, the axial protrusion is clamped in the axial groove A and the axial groove B respectively, and the axial protrusion, the axial groove A and the axial groove B jointly constitute an anti-rotation structure, so that relative rotation of the three is prevented, and the overall strength and stability of the plug are guaranteed.

[0012] An O-shaped sealing ring is arranged between the pin assembly and the inner layer, so that the sealing performance is improved, the sealing performance of the plug is improved, moisture is prevented from entering the plug, the insulation performance is reduced, and a safety hazard is excluded.

[0013] The injection outer layer is made of rubber material with wear resistance and high toughness, so that the overall strength is enhanced, external impact is absorbed, and the internal structure is protected.

[0014] The inner layer is made of thermoplastic material with excellent heat dissipation performance.

[0015] The inner layer is made of high-strength material to fix the conductive structure, so that stable connection and stability are guaranteed.

[0016] An electric connector comprises the layered thermoplastic prefabricated large-size plug, the socket and the nut, the nut end surface is provided with an inner ring, the inner ring is buckled on the needle shell outer peripheral concave surface, the plug is pushed into the socket, and the plug and the socket are locked together through threaded connection.

[0017] Compared with the prior art, the electric connector has the following beneficial effects:

[0018] 1. Reduce the risk of wire displacement and falling. The integrated structure is divided into inner and outer layers, the volume is changed from large to small, so that the injection pressure and speed are not required to be too high during thermoplastic molding, the impact force of thermoplastic on the wire bundle is reduced, the problems of wire displacement, deformation or falling are avoided, and compared with the integrated thermoplastic large-size socket, the risk of loose connection of the wire caused by too high injection pressure and speed is significantly reduced.

[0019] 2. Avoid uneven cooling problems. The inner layer and the outer layer are respectively injection molded, and the problem of uneven cooling of the thick plastic body is avoided. After the inner layer is rapidly cooled, a stable base is provided for the outer layer, and the secondary molding of the outer layer further enhances the compactness and mechanical strength of the overall structure. The cooling of the layered structure helps to reduce deformation and the generation of pores.

[0020] 3. High Cooling Efficiency: The dual-layer structure design allows for independent optimization of the cooling process for the inner and outer layers. The inner layer has a relatively small volume, making heat dissipation easier and resulting in faster cooling. The outer layer can be injection molded after the inner layer has cooled, avoiding the problems of large volume, long heat conduction and dissipation time, slow cooling speed, and low overall cooling efficiency associated with one-piece molded structures.

[0021] 4. High injection molding efficiency: Because the inner layer cools first, it saves time for the preparation of the outer layer injection. The mold does not need to wait for the whole layer to cool; once the inner layer has cooled, it can quickly switch to the outer layer injection stage, greatly shortening the production cycle. Furthermore, the dual-layer structure makes the injection process more targeted, allowing for optimization of parameters such as injection pressure and flow rate based on the different characteristics of the inner and outer layers, resulting in a smoother and more efficient injection process.

[0022] 5. High yield: Dual-layer molding allows for better control of stress distribution during the molding process, reducing defects caused by material shrinkage or uneven cooling. Furthermore, the inner and outer layers can be optimized in terms of materials and processes, improving overall quality. This avoids deformation and cracking problems caused by uneven material shrinkage and cooling during single-layer molding, thus increasing the yield.

[0023] 6. Impact Resistance and Structural Reinforcement: The double-layer structure significantly enhances plug performance. The injection-molded inner layer uses high-strength injection-molded plastic, which helps to fix the internal conductive structure of the plug, ensuring a stable connection of all components. During daily plugging and unplugging, it can withstand greater external pulling forces, preventing the internal structure from loosening and maintaining stable conductivity. The outer layer uses a high-toughness and high-strength material to completely wrap the inner layer, not only enhancing the overall strength of the plug but also effectively resisting external impacts. When the plug is accidentally dropped or impacted, the outer layer material absorbs the impact energy due to its own toughness, preventing the impact force from being directly transmitted to the internal structure, providing excellent cushioning protection. This perfectly overcomes the problem of balancing multiple properties in a one-piece molding process, providing reliable structural protection and impact resistance for the plug, improving product durability and safety. Attached Figure Description

[0024] Figure 1 This is an exploded view of an embodiment of the present invention (connection of the pin assembly and the wire harness);

[0025] Figure 2 This is an exploded view of an embodiment of the present invention (with the pin assembly and wire harness separated);

[0026] Figure 3 This is a schematic diagram of the first thermoplastic prefabricated half-section structure of this utility model embodiment;

[0027] Figure 4 This is a schematic diagram of the first layered thermoplastic prefabricated half-section structure of this utility model embodiment;

[0028] Figure 5 is a half-split structure schematic diagram of the embodiment of the utility model;

[0029] Figure 6 is Figure 5 A-A split positioning engagement positioning structure schematic diagram;

[0030] Figure 7 is Figure 5 B-B split positioning anti-rotation alignment structure schematic.

[0031] Reference signs: 1, pin assembly;1-1, pin;1-2, pin seat;1-2-1, axial groove A;1-3, pin shell;1-3-1, convex ring;1-3-2, outer convex ring;1-3-3, axial protrusion;1-4, sealing ring;2, wire harness;3, injection inner layer;3-1, positioning recess;3-2, axial groove B;4, injection outer layer;4-1, positioning convex part;5, nut. DETAILED DESCRIPTION

[0032] The application will be further described in detail below in conjunction with specific embodiments.

[0033] Embodiment 1.

[0034] Referring to Figures 1-7 , a layered thermoplastic prefabricated large-size electrical connector plug, comprising a pin assembly 1, a wire harness 2, an injection inner layer 3, an injection outer layer 4 and a positioning engagement structure. Among them:

[0035] Pin assembly 1: as the core part of the electrical connector plug, used to realize electrical connection.

[0036] Wire harness 2: fixedly connected with pin assembly 1, used for transmitting electric energy.

[0037] Injection inner layer 3: wrapped outside pin assembly 1 and wire harness 2, made by one-time thermoplastic forming process. Since the thickness of injection inner layer 3 is significantly reduced compared with the traditional single-layer structure, it does not need too high injection pressure and temperature in the forming process. Lower injection pressure reduces the impact force of high temperature and high pressure on wire harness 2, avoiding the risk of wire displacement, deformation or falling off. At the same time, the thin plastic body shrinks uniformly during cooling, reducing the deformation problem caused by uneven cooling. In addition, lower injection pressure and temperature also reduce the generation of pores in the plastic body, improving the density and mechanical strength of injection inner layer 3. The preliminary forming of injection inner layer 3 provides a stable foundation for the subsequent secondary thermoplastic forming.

[0038] The injection-molded outer layer 4 is made by a thermoplastic forming process and wraps outside the injection-molded inner layer 3. Since the injection-molded inner layer 3 has already provided preliminary fixation and protection, the injection-molded outer layer 4 does not require excessively high injection pressure and temperature during the forming process. The lower injection pressure further reduces the risk of wire displacement and deformation. The thickened design of the injection-molded outer layer 4 enhances the overall mechanical strength and insulation performance of the plug, while avoiding cooling deformation and air hole problems caused by over-thick plastic body formed at one time. The secondary forming process of the injection-molded outer layer 4 also allows more precise control of the thickness and distribution of the plastic body, further improving the dimensional stability and appearance quality of the plug.

[0039] Positioning engagement structure: provided between the outer layer 3 and the inner layer 4, limiting the interlayer movement of the two layers, making the inner and outer layers form a whole, enhancing the overall stability and reliability, and ensuring that the injection-molded outer layer 4 can be accurately and firmly combined with the injection-molded inner layer 3 during the thermoplastic forming process.

[0040] Through this "smaller and thinner" double-layer structure design, the shortcomings of the existing large-specification electrical connector plug in one-time thermoplastic forming are overcome. Since the thickness of the injection-molded inner layer 3 and the injection-molded outer layer 4 is significantly reduced compared to the overall thickness when formed in one piece, excessively high injection pressure and temperature are no longer required during the forming process, reducing the probability of problems such as wire displacement, deformation, and air holes. The preliminary formation of the injection-molded inner layer 3 provides a stable foundation for the secondary formation of the outer layer 4, while the design of the outer layer 4 further enhances the mechanical strength and insulation performance of the plug. The positioning engagement structure ensures the firm combination of the outer layer, improving the torsional strength and overall structural stability, reliability, and durability of the plug.

[0041] Thermoplastic forming steps of the double-layer structure plug:

[0042] First, the injection-molded inner layer 3 is made by thermoplastic forming, wrapping the pin assembly 1 and the wire bundle 2. A recess 3-1 is formed on the outer peripheral surface of the injection-molded inner layer 3. Then, the injection-molded outer layer 4 is formed on the outside of the injection-molded inner layer 3 by secondary thermoplastic forming, completely covering the injection-molded inner layer 3. At the same time, a protrusion 3-2 is injection-molded on the inner peripheral surface of the injection-molded outer layer 4, forming a positioning engagement structure between the inner and outer layers. This structure can effectively limit the relative rotation and axial movement between the outer and inner layers. Compared to a one-piece single-layer structure, the double-layer structure can better disperse stress, improve bending stiffness and plug torsional strength, and ensure stable mechanical and electrical performance in complex use environments.

[0043] The monomer structure is decomposed into a double structure, and by setting an injection inner layer and an injection outer layer, the plug body is realized by split injection. The amount of material used for each injection is reduced, the cooling efficiency is improved, the glue can be quickly shaped, the cold shrinkage deformation problem is effectively avoided, the yield is improved, the split rapid injection of the plug is realized, and the injection efficiency of the plug is greatly improved. Its advantages are obvious:

[0044] 1. Stress dispersion: In a single-layer structure, stress is mainly concentrated in a single material layer, which can easily lead to local stress concentration, especially when the plug is bent or twisted. Stress concentration can accelerate material fatigue and reduce strength. In a double-layer structure, the inner and outer layers share stress through positioning engagement structures, making stress distribution more uniform and avoiding local stress concentration, thereby improving overall strength.

[0045] 2. Inner and outer repair, better performance. The double-layer structure can be designed with different materials or different properties of thermoplastic materials. For example, the inner layer can be made of high-strength material to withstand the mechanical stress of the pin assembly, while the outer layer can be made of material with better toughness to absorb external impact. This material optimization further enhances overall strength and insulation performance, overcoming the difficulty of one-piece molding materials to simultaneously meet strength, toughness and flowability requirements. Solving the problem of balancing the performance of the integrated structure material, improving the durability and safety of the plug.

[0046] 3. Durable and fatigue-resistant: delays material fatigue and improves durability. Single-layer structures are prone to cracking or breaking due to stress concentration and material fatigue during long-term use. The double-layer structure reduces local stress concentration and delays the occurrence of material fatigue, thereby improving durability.

[0047] 4. Good environmental adaptability: through layered design, the adaptability to complex environments is increased. Single-layer structures are prone to performance degradation in complex environments (such as high temperature, high humidity or vibration) due to the single material. The double-layer structure can be designed with different materials for the inner and outer layers to enhance environmental adaptability. For example, the outer layer can be made of material with better weather resistance to resist external environmental erosion, while the inner layer focuses on the stability of mechanical properties.

[0048] 5. Strong impact resistance: Single-layer structures are prone to damage when subjected to external impact, as impact energy is directly transmitted to the entire structure. The outer layer of the double-layer structure can act as a buffer to absorb some of the impact energy, thereby protecting the inner layer and pin assembly and improving overall impact resistance. It is particularly suitable for high-altitude drop performance venues.

[0049] 6. High injection efficiency: The double-layer structure can optimize the injection process of the inner and outer layers respectively, reducing the injection time. For example, the inner layer can be quickly formed, and the outer layer can be injected after the inner layer cools down, avoiding the complexity of simultaneous injection, which requires simultaneous processing of the entire structure, resulting in longer injection time.

[0050] Embodiment 2.

[0051] Referring to Figure 2 , Figure 4 The positioning engagement structure in this embodiment is composed of a positioning recess 3-1 provided on the outer circumferential surface of the injection inner layer 3, and a positioning protrusion 4-1 provided on the inner circumferential surface of the injection outer layer 4 and adapted to engage with the positioning recess 3-1. The positioning protrusion 4-1 and the positioning recess 3-1 engage with each other, preventing relative movement and rotation between the outer layer 4 and the inner layer 3. Through thermoplastic forming, the two layers are integrated and tightly combined, avoiding structural loosening caused by thermal expansion or external force, further improving the torsional strength and overall structural stability of the plug, and ensuring the dimensional stability and plug-in adaptability of the plug.

[0052] Embodiment 3.

[0053] Referring to Figures 3-5 In this embodiment, the pin assembly 1 includes a pin 1-1, a pin seat 1-2, and a pin shell 1-3. The pin 1-1 is fixedly connected to the pin seat 1-2, and the pin seat 1-2 is fixed in the pin shell 1-3. The outer circumferential surface of the end portion of the pin shell 1-3 is provided with an outer protruding ring 1-3-2, which is clamped in the end portion of the injection inner layer 3. This structure forms a mechanism lock structure through the close cooperation of the outer protruding ring and the injection inner layer, limiting the relative movement of the two in the axial direction, improving the adhesion between the pin assembly 1 and the inner layer 3, and enabling the inner layer to obtain sufficient strength and torsional resistance through the support of the protruding ring and the thermoplastic effect even with reduced thickness. Furthermore, it also has the following advantages: 1. Enhanced sealing: The close cooperation of the outer protruding ring and the injection inner layer forms an effective mechanical seal, preventing liquids, dust, or other contaminants from entering the interior of the pin shell, improving the environmental adaptability and reliability of the plug. 2. Stress dispersion: The circular structure of the outer protruding ring can evenly distribute the stress between the pin assembly and the inner layer, avoiding stress concentration and thus reducing local fatigue damage, improving the durability and service life of the plug.

[0054] Embodiment 4

[0055] Referring to Figure 7In this embodiment, the inner circumferential surface of the needle shell 1-3 is provided with an axial protrusion 1-3-3, the outer circumferential surface of the needle seat 1-2 is provided with an axial groove 1-2-1 at the corresponding position, and the inner layer 3 is provided with a groove at the corresponding position. The axial protrusion 1-3-3 of the needle shell, the axial groove 1-3-4 of the needle seat, and the groove of the inner layer cooperate with each other to form another anti-rotation structure, which prevents the relative rotation between the needle shell 1-3, the needle seat 1-2, and the inner layer 3, and further improves the overall strength and stability of the plug. At the same time, through the inner layer injection molding, the bonding force between the pin assembly and the inner layer material is increased, so that the two can be more closely integrated. This design not only improves the structural strength and durability of the product, but also enhances its adaptability in harsh environments.

[0056] Embodiment 5

[0057] Referring to Figure 3 , Figure 4 In this embodiment, an O-shaped sealing ring is arranged between the needle shell 1-3 and the inner layer 3, and the O-shaped sealing ring is embedded in the ring groove of the peripheral part of the needle shell 1-3. The sealing performance of the plug is improved, the intrusion of impurities such as water and dust is prevented, the insulation performance is avoided to decline, the safety hidden danger is excluded, the service life of the electrical connector is prolonged, the environmental adaptability of the plug is improved, the reliability and stability of the electrical connection are ensured, and the plug can still maintain excellent performance in harsh environments.

[0058] Embodiment 6

[0059] In this embodiment, the outer layer 4 of the thermoplastic molding is made of nitrile rubber (NBR) material. Nitrile rubber has excellent wear resistance and good toughness, good thermal stability, and can maintain stable chemical and physical properties when hot injection molding at 150-200℃, and has good flowability, can fill complex cavities in the mold, and form a three-dimensional network structure after vulcanization reaction, so that the plug can maintain good performance even in harsh environments, prolonging its service life. Moreover, thanks to the properties of nitrile rubber, the plug can withstand the impact of high-altitude falling and is not easily damaged.

[0060] Embodiment 7

[0061] In this embodiment, the inner layer 3 of the thermoplastic molding is made of polybutylene terephthalate (PBT) material. PBT is a crystalline thermoplastic polyester with fast crystallization speed, which is beneficial to hot injection molding and cooling and setting. The hot injection molding temperature is 230-280℃, the melt flowability is good, and the mold cavity can be filled under low pressure. The molded product has excellent mechanical, insulating, and heat dissipation properties, can effectively conduct the heat generated by the pin assembly, prevent performance degradation or damage due to overheating, ensure the safety and reliability of the plug during high-current transmission, and improve the stability of the electrical connector.

[0062] Secondary injection molding process:

[0063] 1. Assemble the pin assembly: First, fix the pin 1-1 to the pin base 1-2, ensuring that the connection is stable and not loose. Then, install the pin base 1-2 inside the pin shell 1-3, ensuring that the protruding ring 1-3-1 at the end of the pin shell 1-3 is in the correct position. After completing the above operations, the wire bundle (cable) is fixed to the pin.

[0064] 2. Install the sealing ring and nut: Install the O-ring between the injection inner layer 3 and the pin assembly to ensure good sealing performance. Then, snap the inner ring on the end surface of the nut 5 on the outer peripheral concave surface of the pin shell, ensuring that the nut is installed in place.

[0065] 3. Inner layer thermoplastic forming: Place the installed pin assembly 1, wire bundle 2, O-ring, and nut 5 into the mold for one-time thermoplastic forming. During the forming process, the glue will wrap the pin assembly and wire bundle, forming the inner layer 3. At the same time, the protruding ring 1-3-1 at the end of the pin shell 1-3 is clamped on the end of the inner layer 3, and the injection inner layer 3 will be injected with an axial groove B corresponding to the axial protrusion on the inner surface of the pin shell, achieving a tight fit.

[0066] 4. Outer layer thermoplastic forming: Place the plug with the inner layer 3 into another mold for two-time thermoplastic forming to form the injection outer layer 4 that wraps the injection inner layer 3. At the same time, the inner surface of the outer layer 4 will form a positioning protrusion 4-1 that fits into the positioning recess 3-1 on the outer surface of the injection inner layer 3, further enhancing the strength and stability of the overall structure.

[0067] 5. Use test: Connect the completed plug with the socket, align the corresponding ports of the plug and socket first. Rotate the nut 5 to push the plug into the socket, and use the tight fit of the threads on the nut and the corresponding threads on the socket to securely lock the plug and socket together, completing the assembly of the electrical connector. After assembly, the electrical connector is tested for performance according to relevant standards and specifications, such as electrical performance testing (including resistance, insulation resistance, etc.), sealing performance testing, mechanical strength testing, etc.

Claims

1. A layered thermoplastic preformed large format electrical connector plug, characterized by: The plug comprises a pin assembly (1), a wire harness (2) fixedly connected with the pin assembly (1), an injection-molded inner layer (3) wrapped outside the pin assembly (1) and the wire harness (2) and formed by one-time thermoplastic molding, and an injection-molded outer layer (4) wrapped outside the injection-molded inner layer (3) and formed by two-time injection molding. A positioning engagement structure is arranged between the injection-molded outer layer (4) and the injection-molded inner layer (3) to limit the relative rotation and axial movement therebetween, thereby improving the torsional strength and overall structural stability of the plug.

2. The layered thermoplastic preform large format electrical connector plug of claim 1, wherein: The positioning engagement structure comprises a positioning recess (3-1) arranged on the peripheral surface of the injection-molded inner layer (3) and a positioning protrusion (4-1) arranged on the inner peripheral surface of the injection-molded outer layer (4) and adapted to be engaged with the positioning recess (3-1). The positioning protrusion (4-1) and the positioning recess (3-1) are engaged with each other to prevent the relative movement between the outer layer (4) and the inner layer (3), thereby achieving the anti-rotation and axial movement positioning of the two layers.

3. The layered thermoplastic preform large format electrical connector plug of claim 1, wherein: The pin assembly comprises a pin (1-1), a pin seat (1-2) and a pin shell (1-3). The pin (1-1) is fixedly connected to the pin seat (1-2). The pin seat (1-2) is fixed in the pin shell (1-3). The inner peripheral surface of the pin shell (1-3) is provided with a convex ring (1-3-1) which is pressed against the end surface of the pin seat (1-2) to limit the axial movement thereof.

4. The layered thermoplastic preform large format electrical connector plug of claim 3, wherein: The outer peripheral surface of the end portion of the pin shell (1-3) is provided with an outer convex ring (1-3-2) which is arranged in the end portion of the injection-molded inner layer (3) to ensure that the two layers do not move axially.

5. The layered thermoplastic preform large format electrical connector plug of claim 4, wherein: The inner peripheral surface of the pin shell is provided with an axial protrusion. The outer peripheral surface of the pin seat (1-2) is provided with an axial groove A (1-2-1) at a corresponding position. The injection-molded inner layer (3) is provided with an axial groove B (3-2) at a corresponding position. The axial protrusion (1-3-3) is arranged in the axial groove A (1-2-1) and the axial groove B, respectively, to jointly form an anti-rotation structure for preventing the relative rotation of the three layers, thereby ensuring the overall strength and stability of the plug.

6. The layered thermoplastic preform large format electrical connector plug of claim 1, wherein: An O-shaped sealing ring is arranged between the pin assembly (1) and the inner layer (3) to increase the sealing performance.

7. The layered thermoplastic preform large format electrical connector plug of claim 1, wherein: The injection-molded outer layer (4) is made of rubber material which is wear-resistant and strong in toughness.

8. The layered thermoplastic preform large format electrical connector plug of claim 1, wherein: The injection-molded inner layer (3) is made of thermoplastic material which has excellent heat dissipation performance.

9. An electric connector comprising the layered thermoplastic preformed large-size plug according to any one of claims 1-6.

10. An electrical connector as claimed in claim 9, wherein: The plug comprises a socket and a nut (5). The end surface of the nut (5) is provided with an inner ring for pushing the plug into the socket and locking the plug and the socket together through threaded connection.

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