On-site medium-voltage cable joint mold injection device
Through the injection molding technology of the molding device, thermally crosslinked polyethylene material of the same material as the cable is used to solve the problem of dust and water vapor infiltration during the winding of the on-site cable joint, and the same life and high thermal elongation of the joint and the cable body are achieved. Meet the standard requirements.
Patent Information
- Application Number
- CN202421129345.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-22
- Publication Date
- 2024-12-31
- Estimated Expiration
- 2034-05-22
AI Technical Summary
The existing on-site cable joints are prone to mix dust and water vapor during the winding process. The difference in insulation between the materials and cables leads to poor welding strength and intimacy, affecting service life, and the thermal elongation does not meet the standards and cannot meet the standard requirements.
The molding device is used to pass the injection molding mechanism and the mold mechanism, and use low-density thermally cross-linked polyethylene material of the same material as the cable, and the upper and lower double-head injection molding is formed to form a closed cavity structure, and the electric heating plate and compressed gas are used to ensure the high-temperature cross-link of the insulator. , exhaust nitrogen to form high-quality joints.
It ensures that the joint and the cable body have the same life, isolate the environment dust and water vapor, improves the thermal elongation of the insulator, meets the standard requirements, and extends the service life of the cable.
Smart Images
Figure CN222271039U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of cable maintenance, in particular to an on-site medium-voltage cable joint injection molding device. Background Art
[0002] During the laying of medium voltage cables, if they are not properly protected, the cables may be damaged or insufficient in length. In this case, the cables need to be repaired and connected, that is, the functional layers of the cables need to be restored. A good connection should have the same lifespan as the cable itself, be able to adapt to environmental conditions, and maintain the normal operation of the cable.
[0003] At present, the method of on-site cable joints is to restore the inner semi-conductive layer, insulating layer and outer shielding layer after the conductor is welded and trimmed. It is mainly based on the method of winding and filling with strip semi-conductive tape and polyethylene insulating tape, and then wrapping a layer of polytetrafluoroethylene high-temperature tape and copper tape on the outside, and then heating and welding into a whole by winding mixed belt or using a torch. The advantages of this method are convenient construction, less tools and light load for workers, and it is particularly suitable for field operations, but the disadvantages are also obvious. First, dust is easily mixed in during the winding process, and the air cannot be completely discharged during the layered winding process, and water vapor in the air is inevitably mixed in. Second, the winding tape material is different from the cable body insulation. After melting, the critical surface fusion strength and intimacy of the cable body insulation are not good. In the subsequent long-term operation, it is easy to penetrate water vapor or other gases, causing creepage breakdown and affecting the service life. Another particularly important point is that through the investigation of the self-vulcanized insulating tape material and the detection after the joint is completed, the insulation internal cross-linking technical indicator-thermal elongation does not meet the standard, which reduces the cable operating temperature tolerance and shortens the service life. This is not allowed in the standard. In other words, most of the cable joints on site currently fail to meet the standard requirements, but because they cannot be tested on site, this phenomenon cannot be revealed, which poses a hidden danger to cable operation. Utility Model Content
[0004] The utility model aims to provide an on-site medium-voltage cable joint injection molding device, which repairs or joints the cable by means of glue injection molding, thereby ensuring that the joint position and the cable are equally durable.
[0005] In order to achieve the above purpose, the utility model is implemented through the following technical solutions:
[0006] An on-site medium-voltage cable joint injection molding device comprises an injection molding mechanism and a mold mechanism.
[0007] The mold mechanism comprises a mold body, an injection cavity is arranged in the mold body along its length direction, the mold body is divided into an independent upper shell and a lower shell along the axis of the injection cavity, and injection holes communicating with the injection cavity are respectively arranged in the middle of the upper shell and the middle of the lower shell;
[0008] The injection molding mechanism includes a screw conveyor, one end of which is provided with an extrusion port, the extrusion port is connected to a colloid dispensing body, the colloid dispensing body includes a feed pipe threadedly connected to the extrusion port, the colloid dispensing body is C-shaped as a whole, and includes an upper injection molding part and a lower injection molding part symmetrically arranged relative to the feed pipe, and the ends of the upper injection molding part and the lower injection molding part are respectively threadedly connected to spiral connectors.
[0009] Both ends of the mold body are respectively provided with mounting grooves coaxially connected to the injection cavity, and an insulation tube is matched in the mounting groove. The outer end of the insulation tube is provided with a baffle flange located outside the mold body, and the insulation tube includes two symmetrical insulation half tubes separated in half from the axis.
[0010] The upper shell and the lower shell are fixed by screws.
[0011] Annular grooves are provided at both ends of the injection molding cavity, an exhaust hole is penetrated through the upper shell body, and the inner end of the exhaust hole is connected with the annular groove. An exhaust groove is provided on the inner wall of the injection molding cavity around the annular groove, and the outer end of the exhaust groove is connected with the annular groove. The exhaust groove extends inward along the axis of the injection molding cavity.
[0012] An electric heating plate is arranged in the middle of the injection cavity. The electric heating plate is an arc-shaped plate and is divided into two pieces which are respectively fixed on the upper shell and the lower shell.
[0013] The outer end of the injection hole is provided with a circular boss protruding from the upper shell or the lower shell, and a guide groove is centrally provided on the outer end face of the circular boss, the bottom of the guide groove is conical or truncated cone-shaped, and the end with a smaller diameter of the guide groove is coaxially connected to the injection hole; the outer end of the spiral connector is provided with a glue injection nozzle, and the terminal end face of the glue injection nozzle is provided with a chamfered surface that matches the guide groove on the circular boss.
[0014] An upper injection channel is provided in the upper injection molding part along its extension direction, and a lower injection channel is provided in the lower injection molding part along its extension direction. The inner ends of the upper injection channel and the lower injection channel are both connected to the inner end of the feed pipe.
[0015] Compared with the prior art, the beneficial effects of the present invention are:
[0016] The cable is wrapped with a mold body separated from the upper and lower parts to obtain a specific injection molding cavity. Through upper and lower double-head injection molding, the same material as the cable is used. The cable body insulation and the post-injection insulation are fused into one, so that water vapor in the operating environment will not penetrate, ensuring the same service life of the connector and the cable body. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Figure 1 It is a schematic diagram of the utility model.
[0018] Figure 2 It is a side schematic diagram of the utility model.
[0019] Figure 3 It is a structural schematic diagram of the colloid dispensing body and the mold mechanism at the glue injection channel of the utility model.
[0020] Figure 4 It is a schematic diagram of component disassembly of the mold mechanism of the utility model.
[0021] Figure 5 It is a vertical cross-sectional schematic diagram of the mold mechanism of the utility model along the axis.
[0022] Numbers shown in the accompanying drawings:
[0023] 1. Insulation tube; 2. Injection molding cavity; 3. Upper shell; 4. Lower shell; 5. Injection hole; 6. Circular boss; 7. Exhaust hole; 8. Annular groove; 9. Exhaust groove; 10. Screw conveyor; 11. Driving motor; 12. Speed reducer; 13. Feed inlet; 14. Extrusion outlet; 15. Colloid distributor; 16. Feed pipe; 17. Upper injection molding part; 18. Lower injection molding part; 19. Spiral connector; 20. Glue injection nozzle. DETAILED DESCRIPTION
[0024] The present invention is further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the present application.
[0025] The instruments, reagents, materials, etc. involved in the following embodiments, unless otherwise specified, are all conventional instruments, reagents, materials, etc. in the prior art and can be obtained through regular commercial channels. The experimental methods, detection methods, etc. involved in the following embodiments, unless otherwise specified, are all conventional experimental methods, detection methods, etc. in the prior art.
[0026] Example 1: An on-site medium voltage cable connector injection molding device
[0027] During the laying of medium voltage cables, if they are not properly protected, the cables may be damaged or insufficient in length. In this case, the cables need to be repaired and connected, that is, the functional layers of the cables need to be restored. A good connection should have the same lifespan as the cable itself, be able to adapt to environmental conditions, and maintain the normal operation of the cable.
[0028] At present, the method of on-site cable joints is to restore the inner semi-conductive layer, insulating layer and outer shielding layer after the conductor is welded and trimmed. It is mainly based on the method of winding and filling with strip semi-conductive tape and polyethylene insulating tape, and then wrapping a layer of polytetrafluoroethylene high-temperature tape and copper tape on the outside, and then heating and welding into a whole by winding mixed belt or using a torch. The advantages of this method are convenient construction, less tools and light load for workers, and it is particularly suitable for field operations, but the disadvantages are also obvious. First, dust is easily mixed in during the winding process, and the air cannot be completely discharged during the layered winding process, and water vapor in the air is inevitably mixed in. Second, the winding tape material is different from the cable body insulation. After melting, the critical surface fusion strength and intimacy of the cable body insulation are not good. In the subsequent long-term operation, it is easy to penetrate water vapor or other gases, causing creepage breakdown and affecting the service life. Another particularly important point is that through the investigation of the self-vulcanized insulating tape material and the detection after the joint is completed, the insulation internal cross-linking technical indicator-thermal elongation does not meet the standard, which reduces the cable operating temperature tolerance and shortens the service life. This is not allowed in the standard. In other words, most of the cable joints on site currently fail to meet the standard requirements, but because they cannot be tested on site, this phenomenon cannot be revealed, which poses a hidden danger to cable operation.
[0029] The device can be used directly at the cable maintenance site to repair damaged cables on site.
[0030] The main structure includes: an injection molding mechanism and a mold mechanism.
[0031] The mold mechanism comprises a mold body, both ends of which are respectively provided with mounting grooves, a polytetrafluoroethylene heat-insulating tube 1 corresponding to the inner diameter of the heat-insulating tube 1 is fitted in the mounting groove, and a baffle flange is provided at the outer end of the heat-insulating tube 1.
[0032] The heat-insulating tube 1 comprises two symmetrical heat-insulating half tubes separated from the axis in half, so as to facilitate the wrapping and matching of the cables.
[0033] An injection cavity 2 is provided in the center of the length direction of the mold body, connecting the mounting grooves at both ends. The mold body is horizontally divided into two parts along the axis of the injection cavity 2, namely an upper shell 3 and a lower shell 4. The injection cavity 2 is also divided into a symmetrical structure with a semicircular cross-section, which is convenient for being put on the outside of the cable on site.
[0034] The upper shell 3 and the lower shell 4 are fixed by screws. When the upper and lower shells 4 are enclosed, the two heat-insulating half-tubes are fixed by the mounting grooves, thereby forming a closed cavity structure at the position where a joint or repair is required.
[0035] The two ends of the injection cavity 2 are provided with annular grooves 8, the upper shell 3 is penetrated with exhaust holes 7 whose inner ends are connected with the annular grooves 8, the annular grooves 8 are surrounded by exhaust grooves 9 opened on the inner wall of the injection cavity 2, the outer ends of the exhaust grooves 9 are connected with the annular grooves 8, the exhaust grooves 9 extend inwardly along the axis of the injection cavity 2, the exhaust grooves 9 gradually become shallower from the outside to the inside, and the inner ends of the exhaust grooves 9 are pointed structures, which are used to gather and exhaust at both ends in the process of the molten material being pushed outward and gradually filling the injection cavity 2.
[0036] An electric heating plate is provided in the middle of the injection cavity 2 . The electric heating plate is an arc-shaped plate and is divided into two pieces and fixed on the upper shell 3 and the lower shell 4 respectively.
[0037] An injection hole 5 connected to the injection cavity 2 is respectively provided in the center of the upper shell 3 and the center of the lower shell 4, and a circular boss 6 protruding from the upper shell 3 or the lower shell 4 is provided at the outer end of the injection hole 5. A guide groove is centrally provided on the outer end surface of the circular boss 6, and the bottom of the guide groove is conical or truncated cone-shaped, and the end of the guide groove with a smaller diameter is coaxially connected to the injection hole 5.
[0038] The injection molding mechanism includes a screw conveyor 10, which is a common screw conveyor 10 in the prior art, including a cylindrical horizontally arranged casing, a motor-driven rotating shaft is centrally installed in the casing, and a driving motor 11 with a reducer 12 is matched at one end of the casing. The driving motor 11 is connected to the rotating shaft through the reducer 12, and the rotating shaft is provided with spiral blades for pushing the molten material.
[0039] The housing is provided with a feed port 13 at one end close to the driving motor 11 for feeding raw materials, and an extrusion port 14 is provided at the other end of the housing. A colloid separator 15 is connected and fixed to the extrusion port 14. The colloid separator 15 includes a feed pipe 16 threadedly connected to the extrusion port 14. The colloid separator 15 is C-shaped as a whole, and includes an upper injection molding part 17 and a lower injection molding part 18 symmetrically arranged with respect to the feed pipe 16. An upper injection molding channel is provided in the upper injection molding part 17 along its extension direction, and a lower injection molding channel is provided in the lower injection molding part 18 along its extension direction. The inner ends of the upper injection molding channel and the lower injection molding channel are both connected to the inner end of the feed pipe 16, and the molten material is sent to the two channels through the feed pipe 16.
[0040] The ends of the upper injection molding part 17 and the lower injection molding part 18 are respectively threadedly connected with a spiral connector 19 , and the outer end of the spiral connector 19 has a glue injection nozzle 20 , and the end face of the glue injection nozzle 20 is provided with a chamfered surface that matches the guide groove on the circular boss 6 .
[0041] Based on this device, the specific repair operations performed on site are as follows:
[0042] Clean and trim the damaged part on site to remove gravel stains, etc., and trim the exposed damaged part. If it is a cable joint, in the first step, weld the exposed conductor of the joint part and then trim the joint position.
[0043] Place the lower shell under the cable, with the cable connector or damaged part centered in the middle of the injection cavity, and place the heat-insulating half-tubes in the mounting grooves at both ends. After alignment and correction, snap the upper shell onto the lower shell, and fix them with screws to complete the preparation of the mold body and the cable.
[0044] Connect the mold body to the injection molding mechanism, align the upper and lower spiral connectors with the upper and lower injection holes, rotate the spiral connectors to make the injection nozzle fit closely with the guide groove, and clamp the mold mechanism up and down;
[0045] Use low-density heat-crosslinked polyethylene material, which is the same material as the cable body, to melt it through an extruder, extrude it into the injection molding cavity, and fill it with 0.6MP compressed nitrogen (or inert gases such as carbon dioxide and argon) under pressure. Use an electric heating plate to heat the tube wall to 150 degrees Celsius, keep it for 17 minutes, then stop heating. When it cools to below 50 degrees, the heat-crosslinked polyethylene melt is filled in the semi-conductive layer inside the cable conductor to the inner cavity of the mold to form it. Expel the nitrogen, and remove the upper and lower shells. At this time, the cross-linking degree indicator of the cross-linked polyethylene insulation - the thermal elongation reaches 70-90%, which meets the standard requirements.
[0046] After the mold has cooled, remove it.
[0047] The device can be used to connect or repair cables at construction sites. It uses the same material as the cable, and the cable body insulation and post-injection insulator are fused together to prevent water vapor from penetrating during operation, ensuring the same service life of the connector and the cable body.
[0048] The injection molding process effectively isolates dust and water vapor from the environment. At high temperatures, the surface of the insulator will not oxidize or change color, the vulcanization time is shortened, and the gas in the gaps of the cable conductor will not expand into bubbles.
Claims
1. An on-site medium voltage cable joint injection molding device, characterized in that: Including injection molding mechanism and mold mechanism, The mold mechanism comprises a mold body, an injection cavity is arranged in the mold body along its length direction, the mold body is divided into an independent upper shell and a lower shell along the axis of the injection cavity, and injection holes communicating with the injection cavity are respectively arranged in the middle of the upper shell and the middle of the lower shell; The injection molding mechanism includes a screw conveyor, one end of which is provided with an extrusion port, the extrusion port is connected to a colloid dispensing body, the colloid dispensing body includes a feed pipe threadedly connected to the extrusion port, the colloid dispensing body is C-shaped as a whole, and includes an upper injection molding part and a lower injection molding part symmetrically arranged relative to the feed pipe, and the ends of the upper injection molding part and the lower injection molding part are respectively threadedly connected to spiral connectors.
2. According to claim 1, an on-site medium voltage cable joint injection molding device is characterized in that: Both ends of the mold body are respectively provided with mounting grooves coaxially connected to the injection cavity, and an insulation tube is matched in the mounting groove. The outer end of the insulation tube is provided with a baffle flange located outside the mold body, and the insulation tube includes two symmetrical insulation half tubes separated in half from the axis.
3. According to claim 1, an on-site medium voltage cable joint injection molding device is characterized in that: The upper shell and the lower shell are fixed by screws.
4. According to claim 1, an on-site medium voltage cable joint injection molding device is characterized in that: Annular grooves are provided at both ends of the injection molding cavity, an exhaust hole is penetrated through the upper shell body, and the inner end of the exhaust hole is connected with the annular groove. An exhaust groove is provided on the inner wall of the injection molding cavity around the annular groove, and the outer end of the exhaust groove is connected with the annular groove. The exhaust groove extends inward along the axis of the injection molding cavity.
5. The on-site medium voltage cable joint injection molding device according to claim 1, characterized in that: An electric heating plate is arranged in the middle of the injection cavity. The electric heating plate is an arc-shaped plate and is divided into two pieces which are respectively fixed on the upper shell and the lower shell.
6. The on-site medium voltage cable joint injection molding device according to claim 1, characterized in that: The outer end of the injection hole is provided with a circular boss protruding from the upper shell or the lower shell, and a guide groove is centrally provided on the outer end face of the circular boss, the bottom of the guide groove is conical or truncated cone-shaped, and the end with a smaller diameter of the guide groove is coaxially connected to the injection hole; the outer end of the spiral connector is provided with a glue injection nozzle, and the terminal end face of the glue injection nozzle is provided with a chamfered surface that matches the guide groove on the circular boss.
7. The on-site medium voltage cable joint injection molding device according to claim 1, characterized in that: An upper injection channel is provided in the upper injection molding part along its extension direction, and a lower injection channel is provided in the lower injection molding part along its extension direction. The inner ends of the upper injection channel and the lower injection channel are both connected to the inner end of the feed pipe.