Multifunctional medium-voltage cable for coal mining machine

Abstract

The invention discloses a multifunctional medium-voltage cable for a coal mining machine, which belongs to the technical field of cables and comprises a power wire core unit, a communication wire core unit, a ground wire core unit, an auxiliary wire core unit and an optical fiber unit. The plurality of wire core units are twisted to form a cable core structure; a gap formed by the power wire core unit, the ground wire core unit and the optical fiber unit is filled with semi-conductive silicon-based gel; the interior of each power wire core unit comprises a communication wire core unit, and the exterior of each power wire core unit is coated with a semi-conductive slip layer. The gap is filled with the semi-conductive silica-based gel, so that external impact force can be absorbed, a buffering effect is achieved, and the semi-conductive silica-based gel is cooperated with the semi-conductive slip layer, so that internal friction stress formed by long-term bending of the cable can be greatly reduced, the internal insulating layer is protected from being damaged, and the multifunctional medium-voltage cable which is impact-resistant, bending-resistant and long in service life can be obtained. And the auxiliary wire core unit is also arranged, so that the internal condition of the cable can be monitored in real time, and pre-processing can be performed in advance.

Description

Technical Field

[0001] The invention belongs to the technical field of cables, and in particular relates to a multifunctional medium-pressure cable for coal mining machines. Background Art

[0002] With advancements in coal mining technology, particularly the development of fully mechanized mining equipment and system integration, the requirements for shearers and their ancillary equipment are increasing. As a key piece of equipment in the coal mining process, the performance of shearers directly impacts the overall mine's production efficiency and safety. To adapt to the mechanization, automation, and even intelligentization trends of modern coal mining, shearers must not only be highly efficient but also ensure long-term stable operation in complex underground environments. Cables, as crucial components connecting shearers to external power supplies and control systems, play an indispensable role.

[0003] Traditional shearer cables are primarily used in low-voltage applications, such as flexible shearer cables rated at 1.9 / 3.3kV and below. However, to meet the demands of safe and efficient mining of thick coal seams in large underground coal mines and achieve ultra-high installed power, these low-voltage cables are no longer sufficient. To increase the load capacity of cables, the primary solution is to increase the cross-sectional area of ​​the cable conductor. However, unlimited increases in cross-sectional area increase the cable's outer diameter and weight per meter, limiting the selection of supporting cable clamps and connectors. Furthermore, installation becomes more difficult in the confined underground space. Furthermore, increasing the cable's voltage rating can also increase the load capacity. It is estimated that increasing the voltage rating from 1.9 / 3.3kV to 8.7 / 10kV can triple the load capacity. Furthermore, under compatible load conditions, increasing the voltage rating from 1.9 / 3.3kV to 8.7 / 10kV reduces the cable's copper conductor cross-sectional area to one-quarter of the original value, significantly reducing copper consumption and lowering coal mining costs.

[0004] The operating environment of underground cables in coal mines is very harsh, especially for cables used in coal mining machines, which have a small bending radius and a high bending frequency during operation. First, the cables are squeezed and scratched by coal blocks, and the sheath is easily damaged. Secondly, the adjacent insulation layers and insulation shielding layers inside the cable produce relative sliding motion due to bending, and then due to the action of friction, the insulation shielding layer and insulation layer are damaged, resulting in gradual deterioration of insulation performance and a decrease in the overall service life. Moreover, with the continuous improvement of the technical level of the cable industry, the requirements of coal mine users for cables are also increasing. Now they also require the ability to accurately predict and detect cable faults in harsh environments, and to make early pre-processing for possible problems or trends of continuous deterioration, thereby improving coal mining efficiency. Summary of the Invention

[0005] The purpose of the present invention is to provide a multifunctional medium-voltage coal mining machine cable to meet the high load requirements of coal mining cables, and to obtain a multifunctional cable that is resistant to bending, impact, high voltage and long life.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] The present invention provides a multifunctional medium-voltage coal mining machine cable, which includes a power core unit, a communication core unit, a ground core unit, an auxiliary core unit and an optical fiber unit; the multiple core units are twisted into a cable core structure; the gaps formed by the power core unit, the ground core unit and the optical fiber unit are filled with a semi-conductive silicone gel;

[0008] The power core unit contains a communication core unit inside and is covered with a semi-conductive slip layer outside.

[0009] More preferably, the power line core unit has a hollow structure inside, contains a plurality of power line conductors, is embedded with a tensile core, and has a communication line core unit arranged at the center.

[0010] More preferably, the power line core includes, from the outside to the inside, a semi-conductive slip layer, a power line insulation shielding layer, a power line insulation layer, a power line conductor shielding layer, a power line conductor, a tensile core, a communication line insulation layer and a communication line conductor.

[0011] By adopting the above technical solution, the communication core unit of the present invention is arranged inside the power core unit, which can realize the dual functions of power transmission and signal communication while ensuring the space for the communication line conductor. This structure also makes the cable layout more compact, can reduce the equipment burden, and improve work efficiency; and the communication core unit is arranged inside the power core unit, which can effectively reduce the influence of the external electromagnetic field on the communication signal, forming a layer of efficient electromagnetic shielding barrier. More preferably, multiple layers of insulation layers and insulating shielding layers are provided outside the communication line conductor, which can more effectively isolate the conductor from direct contact with the external environment, improve the insulation performance of the cable and reduce the influence on the communication signal. The combination of multiple core units can meet the safe and efficient mining needs of extra-thick coal seams in large underground coal mines, improve the load power and service life of the cable, and the obtained finished cable has a voltage level of 10kV, which greatly improves the efficiency of coal mining and reduces the cost of coal mining.

[0012] The cable of the present invention is further filled with semi-conductive silicone-based gel in the gap formed by the power core unit, the ground core unit and the optical fiber unit. The introduction of the semi-conductive silicone-based gel can greatly improve the buffering effect of the cable when resisting external forces. It has good conductivity, plasticity and chemical inertness, can ensure the stability and reliability of the cable in long-term operation, and can interact with the semi-conductive slip layer to effectively reduce the internal friction stress generated when the cable is bent, thereby protecting the integrity of the cable insulation shielding layer and improving the service life of the cable.

[0013] The cable of the present invention is also provided with an auxiliary core unit, which can monitor the degradation trend of the cable insulation layer and the outer sheath layer in real time. When the insulation layer and the outer sheath layer are aged or damaged, the auxiliary core unit can respond quickly, providing strong support for the maintenance and management of the cable; and the combination of the semi-conductive silicone-based gel and the semi-conductive slip layer can also provide good conductivity, which can provide the necessary electrical connection for the monitoring circuit of the auxiliary core unit, further improving the monitoring sensitivity, and can make timely pre-processing when problems or degradation trends occur.

[0014] Preferably, the semi-conductive silicone-based gel comprises the following raw materials in mass fractions:

[0015] Liquid silicone 65-90%;

[0016] Graphene 2-10%;

[0017] Ultrafine silver powder 1-5%;

[0018] Graphite powder 10-20%;

[0019] Initiator 0.2~1%.

[0020] More preferably, the particle size of the ultrafine silver powder is 1 to 3 μm.

[0021] More preferably, the average particle size of the graphite powder is 1200 mesh.

[0022] More preferably, the graphene is single-layer graphene; the single-layer graphene has a sheet diameter of 0.5 to 5 μm and a thickness of 0.2 to 0.8 nm.

[0023] More preferably, the initiator includes a combination of one or more of bis(2,4-dichlorobenzoyl) peroxide, dibutyltin dilaurate, di-tert-butyl peroxide, tetraisopropoxy titanate, and azobisisobutyronitrile.

[0024] Preferably, the semi-conductive silicone gel is prepared according to the following method:

[0025] Graphene, ultrafine silver powder, graphite powder and initiator are added to liquid silica gel in sequence, mixed evenly, and then the temperature is raised to 115-125° C., and the mixture is stirred and reacted for 8-12 minutes to obtain a semi-conductive silica-based gel.

[0026] Preferably, the cross-linking degree of the semi-conductive silicone-based gel is 40-50%.

[0027] By adopting the above technical solution, the initiator can quickly decompose free radicals, thereby triggering a cross-linking reaction between the liquid silicone molecular chains, gradually transforming it into a semi-solid, semi-conductive silicone-based gel with a three-dimensional network structure. The silicone-based gel material itself has good elasticity and flexibility, which can absorb external impact forces and act as a buffer. It can also help reduce the internal friction stress caused by long-term bending of the cable, thereby protecting the internal insulation layer from damage, effectively enhancing the cable's impact resistance and bending resistance, and increasing the cable's service life. In addition, the semi-conductive silicone-based gel filled in the gaps between the cores can effectively improve the electric field distribution within the cable, reduce the local electric field strength, and reduce electromagnetic interference, thereby improving the safety of the cable and enhancing the stability of signal transmission.

[0028] Graphite powder, graphene, and ultrafine silver powder are also added to the semi-conductive silicone gel. These powders all possess excellent electrical conductivity, making the silicone gel a good semi-conductor. This helps evenly disperse charge, reducing static electricity accumulation and, consequently, the risk of partial discharge. Graphite powder and graphene are also highly effective thermal conductors. The insulation shielding within a cable is susceptible to damage after frequent bending due to internal stress and friction between adjacent shielding layers, leading to a loss of continuity and integrity. When unbalanced current flows through the cable, internal heat builds up and becomes difficult to conduct away, causing cable degradation. The addition of graphite powder and graphene significantly improves the cable's ability to dissipate heat, preventing insulation degradation or damage caused by overheating, thereby extending the cable's service life and reliability. Graphene and graphite powder also form an effective electromagnetic balancing layer, protecting the cable from external electromagnetic interference and ensuring the quality of signal transmission.

[0029] Ultrafine silver powder has a small particle size and is a highly conductive material. When dispersed in a semi-conductive silicone gel and then filled in the gaps in the wire core, these tiny conductive material particles will fill the tiny gaps on the contact surface, forming countless conductive channels, which is conducive to the conduction of a large amount of current.

[0030] Preferably, the ultrafine silver powder is surface-modified with polyaniline; the surface-modified raw materials include ultrafine silver powder and 2-mercaptoaniline in a mass ratio of 1:(1.8-2.2).

[0031] Preferably, the surface modification treatment comprises the following steps:

[0032] Add 2-mercaptoaniline to water, stir and mix, then add ultrafine silver powder, perform ultrasonic dispersion, adjust the pH value of the solution to 5-6, add an oxidant dropwise, stir and react at room temperature for 20-24 hours, and finally centrifuge, wash and dry to obtain the product.

[0033] More preferably, the oxidizing agent includes a combination of one or more of ammonium persulfate, hydrogen peroxide and potassium permanganate.

[0034] By adopting the above technical solution, the ultrafine silver powder has an ultra-small particle size, a large specific surface area, an increased number of active sites exposed to the air, a higher surface energy, and is easy to form an oxide layer in the air. After oxidation, the ultrafine silver powder will greatly reduce its own conductivity. The formed oxide layer will also lead to changes in the electron migration path, increase the internal resistance of the material, hinder the smooth passage of current, and is not conducive to improving the conductivity of the semi-conductive silicone-based gel.

[0035] Therefore, the ultrafine silver powder was modified, and 2-mercaptoaniline was selected as the raw material, and the thiol-modified polyaniline chain segments were obtained by polymerization. The introduction of thiol groups can increase the affinity between the polyaniline chain segments and the ultrafine silver powder, and can help the polyaniline chain segments to quickly form chemical bonds with the ultrafine silver powder, so that the polyaniline chain segments can be firmly fixed on the surface of the silver powder.

[0036] Surface modification of ultrafine silver powder with polyaniline segments effectively prevents oxygen and other oxidants from directly contacting the silver powder, thereby reducing the possibility of silver powder oxidation. Furthermore, the π-π conjugated structure within the polyaniline segments allows for rapid electron migration, not only without compromising the conductivity of the ultrafine silver powder but also by forming a more efficient electron transfer pathway between the segments and the silver powder, maintaining the ultrafine silver powder's high conductivity.

[0037] Moreover, the ultrafine silver powder after polyaniline surface modification can greatly improve the interfacial bonding strength between the ultrafine silver powder and the contact surface when filling the tiny gaps on the contact surface including the semi-conductive slip layer. During long-term bending or use, it will not affect the formed conductive channel, thereby increasing the service life of the cable.

[0038] Preferably, the raw material of the semi-conductive slip layer is a nylon cloth substrate coated with modified butyl rubber on both sides; the raw material of the modified butyl rubber includes butyl rubber with a mass fraction of 80-95% and graphite powder with a mass fraction of 5-20%.

[0039] Preferably, the thickness of the semiconductive slip layer is 0.2-1 mm.

[0040] More preferably, the modified butyl rubber is coated on both sides of a nylon cloth substrate, and then cut to obtain a semi-conductive slip layer after being cross-linked and cured by radiation.

[0041] Preferably, the average particle size of the graphite powder is 1200 mesh.

[0042] By adopting the above technical solution, a semi-conductive slip layer is coated on the outside of the power core unit. Specifically, it is a nylon cloth substrate coated with modified butyl rubber on both sides. The nylon cloth substrate has good heat resistance and can effectively avoid the impact of cable overheating on the insulation layer and conductor. It also has good mechanical strength and provides physical support. The modified butyl rubber has good flexibility and wear resistance. The composite material obtained by combining the two can maintain structural integrity when the cable is subjected to external force or bending. Combined with semi-conductive silicone-based gel, it can greatly reduce the risk of damage caused by mechanical stress.

[0043] Moreover, after the power core unit is coated with a semi-conductive slip layer, it can allow the core units inside the cable to shift relative to each other to a certain extent, thereby absorbing the pressure or tensile force applied by the outside world and protecting the internal conductor from damage.

[0044] At the same time, the modified butyl rubber has good electrical conductivity, and the physical barrier provided by the nylon cloth substrate also enables the semi-conductive slip layer to help effectively block external electromagnetic interference, ensuring that the signal transmission process of the communication core unit inside the power core unit is not affected, thereby improving the cable's own anti-interference ability.

[0045] Preferably, the cable contains 3 to 9 auxiliary core units; the auxiliary core units are distributed around the semi-conductive slip layer.

[0046] Preferably, the auxiliary core unit includes an auxiliary core unit coated with a semiconductor layer and an auxiliary core unit coated with an insulation layer.

[0047] Preferably, the degradation trend inside the cable is monitored by one or a combination of voltage and / or current changes of the auxiliary core unit and temperature changes of the optical fiber unit.

[0048] By adopting the above technical solution, a plurality of auxiliary core units are further provided in the cable of the present invention, and the auxiliary core units include auxiliary core units coated with a semiconductor layer and auxiliary core units coated with an insulating layer, wherein the auxiliary core units coated with the semiconductor layer can form a loop with the power core units, and the auxiliary core units coated with the insulating layer can form a loop with the semi-conductive sheath layer of the cable, and then by monitoring the voltage and / or current changes of the two loops formed by the auxiliary core units or the temperature changes of the optical fiber units, the internal situation of the cable can be characterized.

[0049] When the insulation layer or outer sheath inside the cable ages or is damaged, the resistance in the loop will change, which will cause changes in the return voltage or current of the auxiliary core unit. When the voltage or current change exceeds the set threshold, it can be inferred that the insulation layer or outer sheath inside the cable has a deterioration trend, and pretreatment can be made in advance and necessary maintenance measures can be taken.

[0050] At the same time, when a cable fault occurs, such as conductor breakage or insulation breakdown, the auxiliary core unit can quickly sense it and send out an early warning signal, providing maintenance personnel with timely fault information, facilitating rapid fault location and repair, ensuring the normal operation of the coal mining machine, and thus improving coal mining efficiency.

[0051] Beneficial effects of the present invention:

[0052] 1. The communication core unit of the present invention is arranged inside the power core unit, which can effectively reduce the impact of external electromagnetic fields on communication signals. The combination of multiple core units can meet the requirements of safe and efficient mining of extra-thick coal seams in large underground coal mines, and improve the load power and service life of the cable.

[0053] 2. The present invention also fills the gaps between the power core unit, the ground core unit and the optical fiber unit with semi-conductive silicone gel, which can absorb external impact force, act as a buffer, and help reduce the internal friction stress formed by long-term bending of the cable, thereby protecting the internal insulation layer from damage. The semi-conductive silicone gel also contains graphite powder, graphene and ultrafine silver powder, which can provide good electrical conductivity; among them, the graphite powder and graphene also have good thermal conductivity, which can improve the ability of the cable to dissipate heat and prevent aging or damage of the insulating material caused by overheating; the ultrafine silver powder can fill the tiny gaps on the contact surface to form countless conductive channels, which is conducive to the conduction of a large amount of current.

[0054] 3. The power core unit of the present invention is also coated with a semi-conductive slip layer on the outside, which can cooperate with the semi-conductive silicone gel to effectively reduce the internal friction stress generated when the cable is bent, thereby protecting the integrity of the cable insulation shielding layer and improving the service life of the cable.

[0055] 4. The cable of the present invention also contains a number of auxiliary core units, which can form a loop with other components of the cable. By real-time monitoring of the current or voltage changes in the loop, the degradation trend of the insulation layer or the outer sheath can be determined, and then necessary maintenance measures can be taken. It can also quickly sense when a fault occurs inside the cable, facilitate rapid positioning and repair of the fault, and effectively improve the working efficiency of the coal mining machine. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] The present invention will be further described below with reference to the accompanying drawings.

[0057] Figure 1 It is a structural schematic diagram of the multifunctional medium-pressure coal mining machine cable provided by the present invention.

[0058] Figure 1 In: 1. Power line conductor; 2. Power line conductor shielding layer; 3. Power line insulation layer; 4. Power line insulation shielding layer; 5. Semi-conductive slip layer; 6. Semi-conductive silicone-based gel; 7. Ground wire conductor; 8. Ground wire core semi-conductive coating layer; 9. Auxiliary unit conductor; 10. Auxiliary unit coating layer; 11. Communication line conductor; 12. Communication line insulation layer; 13. Tensile core; 14. Optical fiber unit; 15. Insulation layer; 16. Outer sheath; 17. Semi-conductive sheath layer. DETAILED DESCRIPTION

[0059] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0060] Preparation Example

[0061] Preparation Example 1: A semiconductive silicone gel was prepared according to the following method:

[0062] Single-layer graphene (sheet diameter of 0.5-5 μm, thickness of 0.2-0.8 nm), ultrafine silver powder (average particle size of 2 μm), graphite powder (average particle size of 1200 mesh) and bis(2,4-dichlorobenzoyl) peroxide were added to liquid silica gel (model LSR7200) in sequence, wherein: liquid silica gel 76.5%, graphene 5%, ultrafine silver powder 3%, graphite powder 15% and bis(2,4-dichlorobenzoyl) peroxide 0.5%. After mixing evenly, the temperature was raised to 120°C and stirred for 10 minutes to obtain a semi-conductive silicone-based gel with an average cross-linking degree of 45%.

[0063] Preparation Example 2 and Preparation Example 3 are semi-conductive silicone-based gels. The only difference from Preparation Example 1 is that the raw material ratio of the semi-conductive silicone-based gel is adjusted, as shown in Table 1:

[0064] Table 1 Raw material ratios of Preparation Examples 1 to 3

[0065] Preparation Example 1 Preparation Example 2 Preparation Example 3 Liquid silicone / % 76.5 76.5 74.5 Single layer graphene / % 5 2 10 Ultrafine silver powder / % 3 1 5 Graphite powder / % 15 20 10 Bis(2,4-dichlorobenzoyl) peroxide / % 0.5 0.5 0.5

[0066] Preparation Example 4, a semi-conductive silicone-based gel, differs from Preparation Example 1 only in that the raw material proportion of ultrafine silver powder is 0.2%, and the proportion of adjusted liquid silicone is 79.3%.

[0067] Preparation Example 5, a semi-conductive silicone-based gel, differs from Preparation Example 1 only in that the raw material proportion of ultrafine silver powder is 8%, and the proportion of adjusted liquid silicone is 71.5%.

[0068] Preparation Example 6, a semi-conductive silicone-based gel, differs from Preparation Example 1 only in that no ultrafine silver powder is added and the proportion of liquid silicone is adjusted to 79.5%.

[0069] Preparation Example 7, a semi-conductive silicon-based gel, differs from Preparation Example 1 only in that no single-layer graphene is added and the proportion of liquid silicone is adjusted to 81.5%.

[0070] Preparation Example 8, a semi-conductive silicone-based gel, differs from Preparation Example 1 only in that no graphite powder is added and the proportion of liquid silicone is adjusted to 91.5%.

[0071] Preparation Example 9, a semi-conductive silicon-based gel, differs from Preparation Example 1 only in that no single-layer graphene and graphite powder are added, and the proportion of liquid silicone is adjusted to 96.5%.

[0072] Preparation Example 10: A semiconductive silicone gel was prepared according to the following method:

[0073] 20 g of 2-mercaptoaniline was added to 250 mL of water, and after stirring and mixing, 10 g of ultrafine silver powder (average particle size of 2 μm) was added, and ultrasonic dispersion was performed. The pH value of the solution was adjusted to 5.5, and 1 g of ammonium persulfate was added dropwise. The reaction was stirred at room temperature for 24 h, and finally, the surface-treated ultrafine silver powder was obtained by centrifugation, washing, and drying.

[0074] Single-layer graphene (sheet diameter of 0.5-5 μm, thickness of 0.2-0.8 nm), the surface-treated ultrafine silver powder prepared above, graphite powder (average particle size of 1200 mesh) and bis(2,4-dichlorobenzoyl) peroxide were added to liquid silica gel (model LSR7200) in sequence, wherein: liquid silica gel 76.5%, graphene 5%, ultrafine silver powder 3%, graphite powder 15% and bis(2,4-dichlorobenzoyl) peroxide 0.5%. After mixing evenly, the temperature was raised to 120° C. and stirred for 10 minutes to obtain a semiconductive silicone-based gel with an average cross-linking degree of 45%.

[0075] Preparation Example 11, a semiconductive silicone-based gel, differs from Preparation Example 10 only in that the amount of 2-mercaptoaniline added is 15 g.

[0076] Preparation Example 12, a semiconductive silicone-based gel, differs from Preparation Example 10 only in that the amount of 2-mercaptoaniline added is 25 g.

[0077] Preparation Example 13 is a semi-conductive silicone-based gel, which is different from Preparation Example 1 only in that the cross-linking degree of the semi-conductive silicone-based gel is adjusted to 30%.

[0078] Preparation Example 14 is a semi-conductive silicone-based gel, which is different from Preparation Example 1 only in that the cross-linking degree of the semi-conductive silicone-based gel is adjusted to 60%.

[0079] Example

[0080] Example 1, a multifunctional medium-pressure coal mining machine cable, which is composed of multiple core units twisted into a cable core structure, the specific structure is as follows Figure 1 As shown. It comprises three power core units, each of which is coated with a semi-conductive slip layer. The semi-conductive slip layer is obtained by double-sided coating of modified butyl rubber on a nylon cloth substrate and then irradiation cross-linking and curing. The raw materials of the modified butyl rubber include 90% butyl rubber and 10% graphite powder (average particle size of 1200 mesh).

[0081] The power line core unit has a hollow structure inside, which contains several power line conductors as support, with a tensile core nested in the middle, and the communication line core unit inside the tensile core.

[0082] An optical fiber unit is arranged in the middle of the three power core units, and three ground core units are evenly and compactly arranged on the periphery. The semi-conductive silicone-based gel prepared in Preparation Example 1 is filled in the gaps between the power core units, the ground core units and the optical fiber units by screw pouring.

[0083] Six auxiliary core units are evenly distributed around the semi-conductive slip layer of the power core unit, of which three are auxiliary core units covered with a semiconductor layer and three are auxiliary core units covered with an insulating layer, and the two types of auxiliary core units are arranged alternately.

[0084] Example 2, a multifunctional medium-pressure coal mining machine cable, differs from Example 1 only in that the semiconductive silicone-based gel prepared in Preparation Example 1 is replaced by an equal amount of the semiconductive silicone-based gel prepared in Preparation Example 2; and the modified butyl rubber raw material on the semiconductive slip layer is 95% butyl rubber and 5% graphite powder (average particle size of 1200 mesh); the number of auxiliary core units is 3 strands.

[0085] Example 3, a multifunctional medium-pressure coal mining machine cable, differs from Example 1 only in that the semiconductive silicone-based gel prepared in Preparation Example 1 is replaced by an equal amount of the semiconductive silicone-based gel prepared in Preparation Example 3; and the modified butyl rubber raw material on the semiconductive slip layer is 80% butyl rubber and 20% graphite powder (average particle size of 1200 mesh); the number of auxiliary core units is 9 strands.

[0086] Example 4 is a multifunctional medium-pressure coal mining machine cable, which differs from Example 1 only in that the semiconductive silicone-based gel prepared in Preparation Example 1 is replaced by an equal amount of the semiconductive silicone-based gel prepared in Preparation Example 4.

[0087] Example 5 is a multifunctional medium-pressure coal mining machine cable, which differs from Example 1 only in that the semiconductive silicone-based gel prepared in Preparation Example 1 is replaced by an equal amount of the semiconductive silicone-based gel prepared in Preparation Example 5.

[0088] Example 6, a multifunctional medium-pressure coal mining machine cable, differs from Example 1 only in that the semiconductive silicone-based gel prepared in Preparation Example 1 is replaced by an equal amount of the semiconductive silicone-based gel prepared in Preparation Example 6.

[0089] Example 7, a multifunctional medium-pressure coal mining machine cable, differs from Example 1 only in that the semiconductive silicone-based gel prepared in Preparation Example 1 is replaced by an equal amount of the semiconductive silicone-based gel prepared in Preparation Example 7.

[0090] Example 8, a multifunctional medium-pressure coal mining machine cable, differs from Example 1 only in that the semiconductive silicone-based gel prepared in Preparation Example 1 is replaced by an equal amount of the semiconductive silicone-based gel prepared in Preparation Example 8.

[0091] Example 9, a multifunctional medium-pressure coal mining machine cable, differs from Example 1 only in that the semiconductive silicone-based gel prepared in Preparation Example 1 is replaced by an equal amount of the semiconductive silicone-based gel prepared in Preparation Example 9.

[0092] Example 10 is a multifunctional medium-pressure coal mining machine cable, which differs from Example 1 only in that the semiconductive silicone-based gel prepared in Preparation Example 1 is replaced by an equal amount of the semiconductive silicone-based gel prepared in Preparation Example 10.

[0093] Example 11 is a multifunctional medium-pressure coal mining machine cable, which differs from Example 1 only in that the semiconductive silicone-based gel prepared in Preparation Example 1 is replaced by an equal amount of the semiconductive silicone-based gel prepared in Preparation Example 11.

[0094] Example 12 is a multifunctional medium-pressure coal mining machine cable. The only difference from Example 1 is that the semiconductive silicone-based gel prepared in Preparation Example 1 is replaced by an equal amount of the semiconductive silicone-based gel prepared in Preparation Example 12.

[0095] Example 13, a multifunctional medium-pressure coal mining machine cable, differs from Example 1 only in that the semiconductive silicone-based gel prepared in Preparation Example 1 is replaced by an equal amount of the semiconductive silicone-based gel prepared in Preparation Example 13.

[0096] Example 14 is a multifunctional medium-pressure coal mining machine cable, which differs from Example 1 only in that the semiconductive silicone-based gel prepared in Preparation Example 1 is replaced by an equal amount of the semiconductive silicone-based gel prepared in Preparation Example 14.

[0097] Example 15 is a multifunctional medium-pressure coal mining machine cable, which differs from Example 1 only in that the modified butyl rubber on the semi-conductive slip layer in Example 1 is replaced by an equal amount of unmodified butyl rubber.

[0098] Comparative Example

[0099] Comparative Example 1 is a multifunctional medium-pressure coal mining machine cable, which differs from Example 1 only in that the semi-conductive silicone-based gel prepared in Preparation Example 1 is not filled in the gap formed by the power core unit, the ground core unit and the optical fiber unit.

[0100] Comparative Example 2 is a multifunctional medium-pressure coal mining machine cable, which differs from Example 1 only in that the power core unit is not covered with a semi-conductive slip layer.

[0101] Comparative Example 3, a multifunctional medium-pressure coal mining machine cable, differs from Example 1 only in that the semi-conductive silicone-based gel prepared in Preparation Example 1 is not filled in the gap formed by the power core unit, the ground core unit and the optical fiber unit, and the power core unit is not coated with a semi-conductive slip layer.

[0102] Performance testing

[0103] According to the relevant records in MT 818.1-2009 "Coal Mine Cables Part 1: General Provisions for Mobile Flexible Cables", the cable samples obtained in the examples and comparative examples were subjected to bending life tests. The test results are shown in Table 2:

[0104] Table 2 Bending life test results

[0105]

[0106] According to Table 2, in combination with Example 1 and Example 9, it can be seen that the bending life of Example 9 is reduced compared to that of Example 1. The reason is that the semi-conductive silicone-based gel in Example 9 does not contain added graphite powder or graphene, which will cause the mechanical properties of the obtained semi-conductive silicone-based gel to be reduced, thereby affecting the overall impact resistance and bending resistance of the cable.

[0107] Combining Example 1 and Example 10, it can be seen that the bending life of Example 10 is improved compared with Example 1. The reason is that the ultrafine silver powder added to the semi-conductive silicone-based gel in Example 10 is surface-modified with polyaniline, which can better improve the dispersion of the ultrafine silver powder in the liquid silicone, avoid stress concentration, and also improve the bonding force between the contact surfaces of different core units, thereby increasing the interaction force between the semi-conductive silicone-based gel and the cable, thereby improving the bending resistance of the material.

[0108] Combining Examples 1, 13, and 14, it can be seen that the flex life of Examples 13 and 14 is reduced compared to that of Example 1. This is primarily due to adjustments to the crosslinking degree of the semiconductive silicone gel in Examples 13 and 14. Specifically, while the crosslinking degree of the semiconductive silicone gel was reduced in Example 13, the gel's fluidity increased, but its mechanical strength and protective function decreased, resulting in a decrease in flex resistance. In Example 14, the crosslinking degree of the semiconductive silicone gel was increased, resulting in a decrease in the gel's flexibility and intermolecular slippage, leading to a decrease in flex resistance.

[0109] Combining Example 1 and Comparative Examples 1 to 3, it can be seen that the bending life of Comparative Examples 1 to 3 is significantly reduced compared to Example 1. The reason is that no semi-conductive silicone-based gel is added in Comparative Example 1, and no semi-conductive slip layer is added in Comparative Example 2, which will make it difficult to eliminate the internal friction stress generated by the cable during long-term bending, resulting in a decrease in bending life and bending resistance. In Comparative Example 3, neither semi-conductive silicone-based gel nor semi-conductive slip layer is added, and the performance degradation is more obvious.

[0110] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0111] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A multifunctional medium-pressure coal mining machine cable, characterized in that: The cable comprises a power core unit, a communication core unit, a ground core unit, an auxiliary core unit and an optical fiber unit; the multiple core units are twisted into a cable core structure; the gaps formed by the power core unit, the ground core unit and the optical fiber unit are filled with a semi-conductive silicone gel; The power core unit contains a communication core unit inside and is covered with a semi-conductive slip layer outside.

2. The multifunctional medium-pressure coal mining machine cable according to claim 1, characterized in that: The semi-conductive silicone-based gel comprises the following raw materials by mass fraction: Liquid silicone 65-90%; Graphene 2-10%; Ultrafine silver powder 1-5%; Graphite powder 10-20%; Initiator 0.2~1%.

3. The multifunctional medium-pressure coal mining machine cable according to claim 2, characterized in that: The semi-conductive silicon-based gel is prepared according to the following method: Graphene, ultrafine silver powder, graphite powder and initiator are added to liquid silica gel in sequence, mixed evenly, and then the temperature is raised to 115-125° C., and the mixture is stirred and reacted for 8-12 minutes to obtain a semi-conductive silica-based gel.

4. The multifunctional medium-pressure coal mining machine cable according to claim 2, characterized in that: The cross-linking degree of the semi-conductive silicon-based gel is 40-50%.

5. The multifunctional medium-pressure coal mining machine cable according to claim 2, characterized in that: The ultrafine silver powder is subjected to surface modification treatment with polyaniline; the surface modification raw materials include ultrafine silver powder and 2-mercaptoaniline in a mass ratio of 1: (1.8-2.2).

6. The multifunctional medium-pressure coal mining machine cable according to claim 5, characterized in that: The surface modification treatment comprises the following steps: Add 2-mercaptoaniline to water, stir and mix, then add ultrafine silver powder, perform ultrasonic dispersion, adjust the pH value of the solution to 5-6, add an oxidant dropwise, stir and react at room temperature for 20-24 hours, and finally centrifuge, wash and dry to obtain the product.

7. The multifunctional medium-pressure coal mining machine cable according to claim 1, characterized in that: The raw material of the semi-conductive slip layer is a nylon cloth substrate coated with modified butyl rubber on both sides; the raw material of the modified butyl rubber includes butyl rubber with a mass fraction of 80-95% and graphite powder with a mass fraction of 5-20%.

8. The multifunctional medium-pressure coal mining machine cable according to claim 1, characterized in that: The cable contains 3 to 9 auxiliary core units; the auxiliary core units are distributed on the periphery of the semi-conductive slip layer.

9. The multifunctional medium-pressure coal mining machine cable according to claim 1, characterized in that: The auxiliary core unit includes an auxiliary core unit covered with a semiconductor layer and an auxiliary core unit covered with an insulation layer.

10. The multifunctional medium-pressure coal mining machine cable according to claim 1, characterized in that: The degradation trend inside the cable is monitored by one or a combination of two of the voltage and / or current changes of the auxiliary core unit and the temperature changes of the optical fiber unit.

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