Insulation recovery method for flexible joint of high-voltage submarine cable

Abstract

The invention discloses an ultrahigh-voltage submarine cable flexible joint insulation recovery method, which comprises the following steps: S1, placement: placing a cable to be processed in a working environment; s2, checking to ensure that the surface of the to-be-processed cable is smooth and clean; s3, mold filling: putting the cable to be processed into an injection mold, installing a cold contraction pipe, and adjusting the position; s4, the cable to be processed in the mold is heated and kept; s5, starting an external plastic extruding machine; s6, the pressure of the mold is kept, discharging is stopped, and the extruder is removed; s7, the injection mold is heated and kept, and cooling is conducted in stages; s8, the injection mold and the cooling pipe are dismantled; according to the recovery method, the steps are simple, only one-time mold installation and extrusion process is needed, the workpiece does not need to be vulcanized after heating is stopped and cooling is completed, and the recovery method can effectively save the preparation process, shorten the process time, improve the production efficiency and be beneficial to guaranteeing the on-time delivery rate of a factory.

Description

Technical Field

[0001] The invention relates to an insulation recovery method for an ultra-high voltage submarine cable flexible joint, belonging to the technical field of cables. Background Art

[0002] With the development of offshore wind power high-voltage transmission technology, the application scale of high-voltage submarine cable docking technology is increasing, and its importance is becoming increasingly prominent. In the process of high-voltage transmission, the submarine cable is generally a continuous line that needs to connect various parts into a whole. Generally, the flexible joint is used to connect the parts after the production of each part is completed in the factory. As the most critical link in the entire submarine cable production, the flexible joint has a structural size domain that is very close to the submarine cable body, and has the same electrical performance, mechanical performance, bending performance and service life as the submarine cable. As a key link in cable production, its production cycle and qualified rate directly affect the production progress and order delivery time, and also have a great impact on the safety of the cable line. The existing flexible joint production process is generally divided into two steps: insulation extrusion and vulcanization. In specific operations, it is necessary to extrude first, then wait for the cable to cool to room temperature, demold and demold, and then load the workpiece into the vulcanization mold after surface treatment, and complete the insulation recovery under nitrogen protection. This treatment method requires cooling, demolding, vulcanization and other steps and requires nitrogen environment protection. The construction period is very long and the operating conditions are relatively harsh, and the production efficiency is low. Summary of the invention

[0003] The purpose of the present invention is to provide a method for restoring insulation of an ultra-high voltage submarine cable factory joint to solve the above technical problems.

[0004] The technical solution for achieving the purpose of the present invention is:

[0005] A method for restoring insulation of an ultra-high voltage submarine cable flexible joint comprises the following steps:

[0006] S1: Placement, placing the cables to be processed in the working environment;

[0007] S2: Check to ensure that the surface of the cable to be processed is smooth and clean;

[0008] S3: Mold installation: put the cable to be processed into the injection mold, install the cold shrink tube, and adjust the position;

[0009] S4: heating and maintaining the cable to be processed in the mold;

[0010] S5: start the external extruder;

[0011] S6: Maintain die pressure, stop discharging and remove extruder;

[0012] S7: heating and maintaining the injection mold, and cooling it down in stages;

[0013] S8: removing the injection mold and cooling pipe;

[0014] S9: Surface modification.

[0015] In the above-mentioned recovery steps, only one mold installation is required, and in the process of insulation recovery, there is no need to load the intermediate product into the vulcanizing bar for vulcanization, which greatly shortens the operation cycle and simplifies the operation steps.

[0016] Further or optionally, in order to fully cover the restoration range, the cable to be processed needs to be placed in an environment with relatively high air cleanliness in step S1, and the range is limited to the section to be processed and at least 2 m on both sides thereof.

[0017] Further or optionally, in order to control the accuracy of the product, the mold used in step S3 is a cooling tube made of silicone rubber, and the position is adjusted in such a way as to ensure that the cable is located at the center of the mold.

[0018] Further or optionally, in order to make the contact between the conductor shielding layer and the recovery layer closer, in step S4, the mold is kept at a temperature of 140° C. for 2 hours, and the cable is kept at a temperature of 130° C.

[0019] Further or optionally, in order to make the recovery area and the cable itself more closely connected to prevent electrical accidents such as leakage, the same insulating particles as the cable body are used in step S5, and the extruder is connected to the extrusion die after the extruder discharge is transparent;

[0020] Further or optionally, in order to achieve better bonding at the material junction, the pressure at the tail end of the mold in step S6 is 1.2 MPa.

[0021] Further or optionally, in order to gradually cool down the material and prevent it from shrinking too quickly, causing the material in the recovery area to shrink and affecting the recovery quality, the temperature in step S7 is divided into three stages, namely, heating to 240°C and holding for 90 minutes; cooling to 230°C and holding for 90 minutes; cooling to 220°C and holding for 60 minutes.

[0022] Further or optionally, in order to make the restored cable more beautiful, the surface modification step in step S9 is divided into rounding and polishing, and the outer diameter of the restored section after modification is not greater than 110% of the outer diameter of the main body.

[0023] By adopting the above technical solution, the present invention has the following beneficial effects:

[0024] (1) The factory flexible joint recovery method of the present invention has simple steps and only requires one mold installation and extrusion process. After stopping heating and completing cooling, the workpiece does not need to be vulcanized. The recovery method can effectively save the preparation process, shorten the process time, and improve production efficiency, which is beneficial for the factory to ensure on-time delivery rate.

[0025] (2) The present invention limits the cleanliness of the operating area and the environment, ensures the coverage of the recovery area, and its recovery effect is more stable.

[0026] (3) The present invention uses a silicone rubber cooling tube and a control cable located at the center of the mold, which has higher accuracy.

[0027] (4) The present invention limits the mold temperature and cable holding temperature and time during the recovery process, which can make the contact between the conductor shielding layer and the recovery layer closer.

[0028] (5) The present invention uses the same insulating particles as the cable body during the recovery process, so that the recovery area and the cable itself are more tightly combined, which can prevent electrical accidents such as leakage.

[0029] (6) The present invention strictly controls the pressure at the tail end of the mold and the cooling rate, so that the recovery material shrinks less, the fault is more uniform after recovery, and the overall effect is better.

[0030] (7) The present invention also performs surface modification, and the surface becomes more beautiful after restoration. DETAILED DESCRIPTION

[0031] (Example 1)

[0032] A method for restoring insulation of an ultra-high voltage submarine cable flexible joint according to this embodiment includes the following steps:

[0033] S1: Placement, placing the cables to be processed in the working environment;

[0034] S2: Check to ensure that the surface of the cable to be processed is smooth and clean;

[0035] S3: Mold installation: put the cable to be processed into the injection mold, install the cold shrink tube, and adjust the position;

[0036] S4: heating and maintaining the cable to be processed in the mold;

[0037] S5: start the external extruder;

[0038] S6: Maintain die pressure, stop discharging and remove extruder;

[0039] S7: heating the injection mold and keeping it warm in stages;

[0040] S8: removing the injection mold and cooling pipe;

[0041] S9: Surface modification.

[0042] In step S1, the cable to be processed needs to be placed in an environment with relatively high air cleanliness, and the restricted range is the section to be processed and at least 2m on both sides thereof. Before placing the material, it is necessary to check whether the surface of the material is smooth, scratch-free and free of impurities to ensure that the contact surface is clean and does not affect the overall strength after subsequent recovery.

[0043] The mold used in step S3 is a cooling tube made of silicone rubber. The position adjustment method is to ensure that the cable is located at the center of the mold. In the specific prevention process, a level can be used to control the accurate position of both sides to prevent deviation.

[0044] In step S4, the mold is kept at a temperature of 140° C. for 2 hours, and the cable is kept at a temperature of 130° C. At this time, the temperature of the insulating material in the mold is relatively high, and the temperature of the runner cable surface drops, which is more conducive to the adhesion of the insulating material on its surface.

[0045] In the step S5, insulating particles identical to those of the cable body are used, and the extruder is connected to the extrusion mold after the extruder discharges transparent material. Before adding, the mold needs to be maintained at 140°C for about 90 minutes to make its internal temperature more uniform. The corresponding extruder temperature is also set to 140°C. After the extruder temperature reaches the set temperature, insulating particles identical to those of the body material are added to the extruder barrel, and the material is discharged while observing the discharge quality. The extruder is stopped after the material discharge reaches a transparent color, and the extruder is quickly connected to the extrusion mold.

[0046] After the extruder is connected to the injection mold, the extruder is turned on at full speed, and attention is paid to the discharge of the material at both ends of the injection mold and the pressure changes at the tail end of the mold. In step S6, the pressure at the tail end of the mold is 1.2Mpa. After the extrusion is completed, glue overflows from both ends of the mold, and the inside of the mold is filled with colloidal material. After recovery, there is less internal gap in the material.

[0047] The temperature in step S7 is divided into three stages, namely, heating to 240° C. and maintaining for 90 minutes; cooling to 230° C. and maintaining for 90 minutes; cooling to 220° C. and maintaining for 60 minutes.

[0048] During the cooling process, pay attention to proceeding step by step so that the material is gradually cooled to avoid excessive cooling, which may cause deformation and delamination between the outer and inner layers due to uneven shrinkage.

[0049] The surface modification step in step S9 is divided into rounding and polishing. The outer diameter of the restored section after modification is not greater than 110% of the outer diameter of the main body. Glass sheets, utility knives, etc. can be used in the rounding process, and sandpaper can be used for polishing.

[0050] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for restoring insulation of an ultra-high voltage submarine cable flexible joint, characterized in that: The following steps are involved: S1: Placement, placing the cables to be processed in the working environment; S2: Check to ensure that the surface of the cable to be processed is smooth and clean; S3: Mold installation: put the cable to be processed into the injection mold, install the cold shrink tube, and adjust the position; S4: heating and maintaining the cable to be processed in the mold; S5: start the external extruder; S6: Maintain die pressure, stop discharging and remove extruder; S7: heating and maintaining the injection mold, and cooling it down in stages; S8: removing the injection mold and cooling pipe; S9: Surface modification.

2. The method for restoring insulation of an ultra-high voltage submarine cable flexible joint according to claim 1, characterized in that: In step S1, the cable to be processed needs to be placed in an environment with relatively high air cleanliness, and the restricted range is the section to be processed and at least 2 m on both sides thereof.

3. The method for restoring insulation of an ultra-high voltage submarine cable flexible joint according to claim 1, characterized in that: The mold used in step S3 is a cooling tube made of silicone rubber, and the position is adjusted in such a way as to ensure that the cable is located at the center of the mold.

4. The method for restoring insulation of an ultra-high voltage submarine cable flexible joint according to claim 1, characterized in that: In step S4, the mold is maintained at a temperature of 140° C. for 2 hours, and the cable is maintained at a temperature of 130° C.

5. The method for restoring insulation of an ultra-high voltage submarine cable flexible joint according to claim 1, characterized in that: In step S5, the same insulating particles as the cable body are used, and the extruder is connected to the extrusion die after the extruder discharge becomes transparent; In step S6, the pressure at the tail end of the mold is 1.2 MPa.

6. The method for restoring insulation of an ultra-high voltage submarine cable flexible joint according to claim 1, characterized in that: The temperature in step S7 is divided into three stages, namely, heating to 240° C. and maintaining for 90 minutes; cooling to 230° C. and maintaining for 90 minutes; cooling to 220° C. and maintaining for 60 minutes.

7. The method for restoring insulation of an ultra-high voltage submarine cable flexible joint according to claim 1, characterized in that: The surface modification step in step S9 is divided into rounding and polishing, and the outer diameter of the restored section after modification is not greater than 110% of the outer diameter of the main body.