High-strength bend-resistant cable for mechanical joints and method of making same

Abstract

The application relates to the technical field of cables, in particular to a high-strength bending-resistant cable for mechanical joints and a preparation method thereof. The cable comprises a cable core and a sheath layer outside the cable core; the cable core is a stranded structure of a stress buffer wire core and multiple insulated wire cores, and on the cross section of the cable core, the multiple insulated wire cores are arranged in a ring shape with the stress buffer wire core as the center, and the outer part of each insulated wire core is coated with a lubricating oil coating; the stress buffer wire core is a filament polyester fiber bundle stranded structure with a bulkiness of greater than or equal to 20 cm3 / g and a compression recovery rate of greater than or equal to 75%. In the process of frequent bending and twisting of the mechanical joint relative movement, the extrusion and friction between the insulated wire cores are small, the abrasion phenomenon of the insulated wire cores is greatly reduced, the whole cable core has good structural strength, excellent bending resistance and excellent twisting resistance, and has a long service life.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cable, in particular to a high-strength bending-resistant cable for mechanical joints and a preparation method thereof. BACKGROUND

[0002] Mechanical joints refer to components used for connection and support of movement in mechanical systems, allowing relative movement between adjacent components, and are widely used in technical fields such as robots and mechanical arms. The cable of a mechanical joint, as a key component for controlling and adapting the relative movement of a mechanical joint, needs to withstand long-term bending and torsional mechanical stress and adapt to complex working environments, so the mechanical joint has high technical requirements for the bending resistance and torsional resistance of the cable.

[0003] In the current design of mechanical joint special cables, the main consideration is how to improve the softness of the cable to achieve ideal bending resistance and torsional resistance technical requirements. The stranding structure of the cable core is a major technical measure to improve the softness of the cable. However, in actual application working conditions, the cable needs to be frequently bent and twisted with the relative movement of the mechanical joint, which causes the insulating cores in the cable core to be frequently squeezed and rubbed, thereby easily causing high-frequency wear and tear of the insulating layer of the insulating core, and the service life is limited. SUMMARY

[0004] The technical purpose of the present application is to provide a mechanical joint cable with high structural strength, excellent bending resistance and torsional resistance, and a preparation method thereof, in view of the particularity of the mechanical joint and the deficiencies of the prior art.

[0005] The technical solution adopted by the present application to achieve the technical purpose is: a high-strength bending-resistant cable for mechanical joints, comprising a cable core and a sheath layer outside the cable core.

[0006] The cable core is a stranding structure of one stress buffer core and multiple insulating cores, and on the cross section of the cable core, the multiple insulating cores are arranged in a ring around the stress buffer core, and each insulating core is coated with a lubricating oil coating on the outside.

[0007] The stress buffer core is a long filament polyester fiber bundle stranding structure with a bulkiness ≥ 20 cm³ / g and a compression recovery rate ≥ 75%.

[0008] Further, the insulating core of the cable core is 3-12, and the stranding pitch ratio is 6-8 times.

[0009] Further, the insulating core is composed of a stranded conductor and an insulating layer wrapped outside.

[0010] The stranded conductor is a stranded structure of multiple conductor units, and the stranded pitch ratio is 8-10 times; each conductor unit is a bundle stranded structure of multiple hard copper alloy wires, and the diameter of the hard copper alloy wire is 0.1 mm, and the tensile strength is greater than or equal to 700 MPa;

[0011] The insulation layer is an extrusion structure of a polyolefin material with an elongation at break greater than or equal to 600% and a tensile strength greater than or equal to 20 MPa.

[0012] Further, the average extrusion thickness of the insulation layer is 0.28 mm ± 0.05 mm.

[0013] Further, the lubricating oil coating is a coating structure of viscous silicone oil on the outer surface of the corresponding insulated core;

[0014] The average coating thickness of the lubricating oil coating is 0.01 mm ± 0.002 mm.

[0015] Further, the outer part of the cable core is sequentially covered with an isolation layer and a sheath layer from the inside to the outside;

[0016] The isolation layer is at least one layer of overlapping wrapping structure of polytetrafluoroethylene turning belt, and the thickness of the isolation layer is 0.05-0.1 mm;

[0017] The sheath layer is an extrusion structure of polyester type thermoplastic polyurethane elastomer.

[0018] Further, the sheath layer is inlaid with a spiral skeleton layer;

[0019] The spiral skeleton layer is a spiral structure of 304 austenitic stainless steel wire or 316 austenitic stainless steel wire with a diameter of 0.2-0.5 mm, and the spiral pitch is 8-16 times the diameter of the wire.

[0020] A preparation method of the high-strength bending-resistant cable for mechanical joints, the preparation method comprising the following process steps:

[0021] Step 1. First, use a wire bundling machine to bundle and twist the selected specification hard copper alloy wire into a conductor unit in a concentric arrangement structure;

[0022] Then use a rewinding machine to twist multiple conductor units together at a set stranded pitch ratio, and the twisting direction is opposite to the bundle twisting direction of the conductor unit, to form a stranded conductor;

[0023] Use a wire bundling machine to bundle and twist the selected specification long filament polyester fiber together as required to form a stress buffer core for standby;

[0024] Step 2. Use an extruder to extrude a selected specification polyolefin material with a set thickness on the outside of the stranded conductor to form an insulation layer;

[0025] Step 3. Adopting a rewinding machine, the insulated wire core of step 2 is subjected to 100% insulation detection;

[0026] And a sizing die is used to coat a layer of silicone oil on the surface of the insulated wire core to form a lubricating oil coating with a set thickness;

[0027] Step 4. Adopting a cabling machine, the stress buffer wire core prepared in step 1 and the plurality of insulated wire cores prepared in step 3 are twisted together in a concentric arrangement structure according to a set twisting pitch ratio;

[0028] In the process of cabling and twisting, a wrapping machine is used to wrap the selected polytetrafluoroethylene turning tape on the outside of the cable core with a set overlap rate;

[0029] Step 5. Adopting a steel wire spiral armoring machine, the selected stainless steel wire is spiral armored on the outside of the cable core of step 4 in a cold working process according to a set pitch;

[0030] Step 6. Adopting an extruding machine, the selected polyester thermoplastic polyurethane elastomer material is extruded on the outside of the cable core of step 5 with a set thickness, and the extruded polyester thermoplastic polyurethane elastomer material fully covers the spiral steel wire of step 5 in the thickness direction;

[0031] Cooling, setting, until the finished product.

[0032] Further, in step 2, the temperature of the front section of the extruder barrel is 130-140°C, the temperature of the middle section is 140-150°C, the temperature of the rear section is 150-170°C, and the temperature of the head is 160-170°C, and the extrusion die matching coefficient DBR is 1.0-1.2, and the stretching coefficient DDR is 1.3-4.0.

[0033] Further, in step 6, before extrusion, the polyester thermoplastic polyurethane elastomer material is subjected to drying treatment using a box-type hot air circulation dryer, the baking temperature is 90-110°C, and the baking time is 3-6h;

[0034] The temperature of the front section of the extruder barrel is 160-180°C, the temperature of the middle section is 190-210°C, the temperature of the rear section is 220-230°C, and the temperature of the head is 215-235°C, and the extrusion die matching coefficient DBR is 1.0-1.2, and the stretching coefficient DDR is 2.5-4.0.

[0035] The beneficial technical effect of the present application is that the above technical measures are aimed at the particularity of the mechanical joint, the cable core of the mechanical joint cable is stranded with multiple insulated wire cores with a lubricating oil coating and a specific stress buffer wire core, the specific stress buffer wire core not only has excellent tensile resistance, but also has good structural creep performance, when each tightly arranged insulated wire core of the cable core is extruded during bending and twisting, the stress buffer wire core can provide sufficient stress buffering and deformation compliance for it to reduce the hard extrusion damage of adjacent insulated wire cores; at the same time, the insulated wire core with a lubricating oil coating has good slipperiness and small friction between adjacent insulated wire cores during bending and twisting; therefore, the multiple insulated wire cores with a lubricating oil coating are tightly arranged around the specific stress buffer wire core, the extrusion and friction between each insulated wire core are small during the frequent bending and twisting of the relative movement of the mechanical joint, which greatly reduces the wear and tear of the insulated wire core, the entire cable core has good structural strength, excellent bending resistance and twisting resistance, and long service life.

[0036] In addition, in the above technical measures, the conductor of the insulated wire core is stranded with a hard copper alloy wire, which not only meets the technical requirements of electric transmission, but also has good softness and high structural strength; the insulating layer of the insulated wire core is formed by polyolefin material with excellent breaking elongation and excellent insulation performance, which can obtain insulated wire cores with good anti-breaking and anti-cracking performance in cooperation with the conductor.

[0037] The sheath layer outside the cable core is formed by a polyester thermoplastic polyurethane elastomer material combined with an embedded spiral stainless steel wire, which not only has the technical characteristics of high and low temperature resistance, moisture resistance, oil resistance and chemical corrosion resistance, but also effectively avoids the technical problem of stress concentration of the cable during small radius bending and twisting while ensuring that the cable has good bending performance and radial compression resistance.

[0038] In summary, the present application effectively guarantees that the formed cable has the technical characteristics of high structural strength, bending resistance, twisting resistance and tensile resistance, effectively meets the working conditions of the mechanical joint, and can serve for a long time compared with the current mechanical joint cable. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 is a structural schematic view of the present application.

[0040] Figure 2 is a cross-sectional structural schematic view of Figure 1 .

[0041] Figure 3 is another structural schematic view of the present application.

[0042] Figure code meaning: 1 - stranded conductor; 2 - insulation layer; 3 - lubricating oil coating; 4 - stress buffer core; 5 - isolation layer; 6 - spiral skeleton layer; 7 - sheath layer. DETAILED DESCRIPTION

[0043] The present application relates to the technical field of cable, in particular to a kind of high-strength bending-resistant cable for mechanical joint, and the preparation method of the cable, the main technical scheme content of the present application is specifically explained as follows by combining multiple embodiments. Among them, embodiment 1 combines the drawing of specification, i.e. Figure 1 And Figure 2 The technical scheme content of the present application is clearly and detailedly explained; embodiment 2 combines the drawing of specification, i.e. Figure 3 The technical scheme content of the present application is clearly and detailedly explained; other embodiments, although not separately drawn, the main structure can still refer to the drawing of embodiment 1 or embodiment 2.

[0044] It needs to be particularly pointed out that the drawing of the present application is schematic, and unnecessary details have been simplified in order to clarify the technical purpose of the present application, to avoid obscuring the technical scheme of the present application contributed to the prior art. In addition, the "about", "substantially" and the like in the following quantity or matching relationship express the meaning of allowing reasonable assembly error, processing error and the like, not the absolute quantity or matching relationship of literal expression.

[0045] Embodiment 1

[0046] Referring to Figure 1 And Figure 2 As shown, the present application is a high-strength, bending-resistant, torsion-resistant, tensile cable for mechanical joint, which comprises a cable core and an isolation layer 5 and a sheath layer 7 outside the cable core.

[0047] Specifically, the cable core is a stranded structure of one stress buffer core 4 and eight insulated cores, and the stranded pitch ratio is about 7 times. Moreover, on the cross section of the cable core, the eight insulated cores are arranged in a ring around the stress buffer core 4.

[0048] In order to obtain excellent tensile properties and good structural creep properties of the cable core, and to provide sufficient stress buffering and deformation space for the corresponding insulated core under extrusion during bending and twisting, reduce the hard extrusion damage between adjacent insulated cores, the stress buffer core 4 as the stranded center of the eight insulated cores is formed by using a filament polyester fiber bundle stranded structure with a bulkiness of about 26 cm³ / g and a compression recovery rate of about 78%, i.e. the eight insulated cores are arranged in a ring around the outer periphery of the stress buffer core 4.

[0049] Each insulated core is composed of a stranded conductor 1 and an insulating layer 2 coated outside. The stranded conductor 1 is a stranded structure of multiple conductor units, and the stranded pitch ratio is about 9 times. Each conductor unit is a bundle stranded structure of multiple hard copper alloy wires (for example, tin copper alloy wires are also preferred), and the diameter of the hard copper alloy wire is about 0.1 mm, and the tensile strength is about 720 MPa. The insulating layer 2 is made of a polyolefin material with a breaking elongation of about 650% and a tensile strength of about 22 MPa, which is extrusion molded outside the stranded conductor 1. The average extrusion thickness of the insulating layer 2 is about 0.28 mm. In the above-mentioned insulated core structure, the stranded conductor not only meets the technical requirements of electric conduction transmission, but also has good softness and high structural strength. The insulating layer has excellent anti-fracture and insulating properties. The final insulated core has good anti-fracture and anti-damage properties, and high structural strength, which effectively adapts to the working environment of mechanical joints.

[0050] In order to further reliably adapt the insulated core to the working environment of the mechanical joint, reduce the extrusion friction force between adjacent insulated cores during bending and twisting, and have a slippable performance between adjacent insulated cores, a layer of lubricating oil coating 3 is coated outside the insulating layer 2 of each insulated core. The lubricating oil coating 3 is made of viscous silicone oil, which is formed in a full-coating structure on the outer surface of the corresponding insulated core. The average coating thickness of the lubricating oil coating 3 on the outer surface of the corresponding insulated core is about 0.01 mm.

[0051] In order to make the above-mentioned cable core relatively round, and facilitate the extrusion molding of the outer sheath layer 7, the isolation layer 5 is coated outside the above-mentioned structural cable core. The isolation layer 5 is a double-layer overlapping wrapped structure of polytetrafluoroethylene turning band, and the overlapping wrapping rate of each layer is about 66%. The average thickness of the isolation layer 5 is about 0.08 mm.

[0052] In order to obtain good environmental resistance such as high and low temperature resistance, moisture resistance, oil resistance, chemical corrosion resistance, etc., the sheath layer 7 is an extrusion structure of polyester type thermoplastic polyurethane elastomer. Moreover, while ensuring that the cable has good bending performance and radial compression resistance, the sheath layer 7 is embedded with a spiral skeleton layer 6. The spiral skeleton layer 6 is a spiral structure of 304 austenitic stainless steel wire with a diameter of about 0.4 mm, and the spiral pitch is about 14 times the diameter of the steel wire.

[0053] The above-mentioned cable structure is prepared by the following process steps:

[0054] Step 1. First, use a wire bundling machine to bundle and twist the selected specification of hard copper alloy wire into a conductor unit in a concentric arrangement structure;

[0055] Then, the multiple conductor units are stranded together with a set pitch ratio by a rewinding machine, and the stranding direction is opposite to the bundle stranding direction of the conductor units, to form stranded conductors;

[0056] Then, the long filament polyester fibers of selected specifications are bundled together with a set requirement by a bundling machine to form a stress buffer core, for standby use;

[0057] Step 2. The selected polyolefin material of a specified specification is extruded on the outside of the stranded conductors with a set thickness by an extruding machine to form an insulation layer;

[0058] The front section temperature of the extruding machine barrel for the insulation layer extrusion is about 135°C, the middle section temperature is about 145°C, the rear section temperature is about 160°C, the head temperature is about 165°C, the mold matching coefficient DBR of the extruding mold is about 1.1, and the stretching coefficient DDR is about 3.0;

[0059] Step 3. The insulation core of Step 2 is subjected to 100% insulation detection by a rewinding machine;

[0060] And a layer of silicone oil is coated on the surface of the insulation core with a set thickness by a sizing mold to form a lubricating oil coating;

[0061] Step 4. The stress buffer core prepared in Step 1 and the multiple insulation cores prepared in Step 3 are stranded together with a set pitch ratio in a concentric arrangement structure by a cabling machine;

[0062] In the process of cabling stranding, the selected polytetrafluoroethylene turning tape is wrapped around the outside of the cable core with a set overlap rate by a wrapping machine;

[0063] Step 5. The selected stainless steel wire of a specified specification is spirally armored on the outside of the cable core of Step 4 in a cold working process by a steel wire spiral armoring machine;

[0064] Step 6. The polyester type thermoplastic polyurethane elastomer material is first subjected to drying treatment by a box-type hot air circulation dryer, and the baking temperature is about 100°C and the baking time is about 4h;

[0065] Then, the selected polyester type thermoplastic polyurethane elastomer material is extruded on the outside of the cable core of Step 5 with a set thickness by an extruding machine, and the extruded polyester type thermoplastic polyurethane elastomer material fully covers the spiral steel wire of Step 5 in the thickness direction;

[0066] The front section temperature of the extruding machine barrel for the sheath layer extrusion is about 170°C, the middle section temperature is about 200°C, the rear section temperature is about 225°C, the head temperature is about 230°C, the mold matching coefficient DBR of the extruding mold is about 1.1, and the stretching coefficient DDR is about 3.0;

[0067] Finally, cool, shape, until the finished product.

[0068] Embodiment 2

[0069] Referring to Figure 3 As shown in the figure, the present application is a high-strength, bend-resistant, twist-resistant, tensile cable for mechanical joints, which comprises a cable core and an isolation layer 5 and a sheath layer 7 outside the cable core.

[0070] Specifically, the cable core is a stranded structure of one stress buffer wire core 4 and six insulated wire cores, and the stranded pitch ratio is about 6 times. Moreover, in the cross section of the cable core, the six insulated wire cores are closely arranged in a ring around the stress buffer wire core 4.

[0071] In order to obtain excellent tensile properties of the cable core and good structural creep properties, and to provide sufficient stress buffering and deformation space for the corresponding insulated wire cores subjected to extrusion during bending and twisting, and to reduce the hard extrusion damage between adjacent insulated wire cores, the stress buffer wire core 4, which is the stranded center of the six insulated wire cores, is formed by a filament polyester fiber bundle stranded structure with a bulkiness of about 20 cm³ / g and a compression recovery rate of about 75%, i.e. the six insulated wire cores are closely arranged in a ring around the outer periphery of the stress buffer wire core 4.

[0072] Each insulated wire core is composed of a stranded conductor 1 and an insulation layer 2 wrapped outside. The stranded conductor 1 is a stranded structure of multiple conductor units, and the stranded pitch ratio is about 8 times. Each conductor unit is a bundle stranded structure of multiple hard copper alloy wires (for example, tin copper alloy wires are also preferred), and the diameter of the hard copper alloy wire is about 0.1 mm, and the tensile strength is about 730 MPa. The insulation layer 2 is made of a polyolefin material with an elongation at break of about 620% and a tensile strength of about 20 MPa, which is extrusion molded outside the stranded conductor 1, and the average extrusion thickness of the insulation layer 2 is about 0.23 mm. In the foregoing insulated wire core structure, the stranded conductor not only meets the technical requirements of electric conduction transmission, but also has good softness and high structural strength, and the insulation layer has excellent anti-breakage and insulation properties. The final obtained insulated wire core has good anti-breakage and anti-damage properties, high structural strength, and effectively adapts to the working conditions of mechanical joints.

[0073] In order to further reliably adapt the insulated wire core to the working conditions of mechanical joints, reduce the extrusion friction force between adjacent insulated wire cores during bending and twisting, and provide a slippable performance between adjacent insulated wire cores, a layer of lubricating oil coating 3 is applied outside the insulation layer 2 of each insulated wire core. The lubricating oil coating 3 is made of viscous silicone oil, which is formed in a full-coating structure on the outer surface of the corresponding insulated wire core, and the average coating thickness of the lubricating oil coating 3 on the outer surface of the corresponding insulated wire core is about 0.008 mm.

[0074] In order to make the above-mentioned cable core relatively round, and facilitate the extrusion molding of the outer sheath layer 7, the isolation layer 5 is wrapped outside the above-mentioned structural cable core. The isolation layer 5 is a single-layer overlapping wrapping structure of polytetrafluoroethylene turning band, and the overlapping wrapping rate is about 85%, and the average thickness of the isolation layer 5 is about 0.05mm.

[0075] In order to obtain good high and low temperature resistance, moisture resistance, oil resistance, chemical corrosion resistance and other environmental resistance, the sheath layer 7 is an extrusion structure of polyester type thermoplastic polyurethane elastomer. Moreover, while ensuring that the cable has good bending performance and radial compression resistance, the sheath layer 7 is embedded with a spiral skeleton layer 6, which is a spiral structure of 316 austenitic stainless steel wire with a diameter of about 0.3mm, and the spiral pitch is about 10 times the diameter of the steel wire.

[0076] The cable with the above-mentioned structure is prepared by the following process steps:

[0077] Step 1. First, use a wire bundling machine to bundle and twist the selected specification of hard copper alloy wire into a conductor unit in a concentric arrangement structure;

[0078] Then, use a rewinding machine to twist together multiple conductor units at a set twisting pitch ratio, and the twisting direction is opposite to the bundle twisting direction of the conductor unit, to form a twisted conductor;

[0079] Use a wire bundling machine to bundle and twist together the selected specification of long filament polyester fiber as required to form a stress buffer core, for standby use;

[0080] Step 2. Use an extruder to extrude a selected specification of polyolefin material outside the twisted conductor at a set thickness to form an insulation layer;

[0081] Among them, the temperature of the front section of the extruder barrel of the insulation layer extrusion is about 130℃, the temperature of the middle section is about 140℃, the temperature of the rear section is about 150℃, and the temperature of the head is about 160℃, and the die matching coefficient DBR of the extrusion die is about 1.0, and the stretching coefficient DDR is about 1.3;

[0082] Step 3. Use a rewinding machine to perform 100% insulation detection on the insulation core of step 2;

[0083] And use a sizing die to coat a layer of silicone oil on the surface of the insulation core at a set thickness to form a lubricating oil coating;

[0084] Step 4. Use a cable forming machine to twist together the stress buffer core prepared in step 1 and the multiple insulation cores prepared in step 3 in a concentric arrangement structure according to a set twisting pitch ratio;

[0085] In the process of cabling and stranding, the selected polytetrafluoroethylene turning tape is wrapped outside the cable core by a wrapping machine with a set overlap rate;

[0086] Step 5. The selected stainless steel wire is spirally armored outside the cable core of step 4 in a cold working process with a set pitch by a steel wire spiral armoring machine;

[0087] Step 6. The polyester thermoplastic polyurethane elastomer material is first dried by a box-type hot air circulating dryer, the baking temperature is about 90 DEG C, and the baking time is about 6h;

[0088] Then, the selected polyester thermoplastic polyurethane elastomer material is extruded outside the cable core of step 5 with a set thickness by an extruder, and the extruded polyester thermoplastic polyurethane elastomer material fully covers the spiral steel wire of step 5 in the thickness direction;

[0089] The temperature of the front section of the extruder barrel of the sheath layer extrusion is about 160 DEG C, the temperature of the middle section is about 190 DEG C, the temperature of the rear section is about 220 DEG C, and the temperature of the die head is about 215 DEG C, and the die matching coefficient DBR of the extrusion die is about 1.0, and the stretching coefficient DDR is about 2.5;

[0090] Finally, cooling and setting until the finished product.

[0091] Example 3

[0092] The application is a high-strength, bend-resistant, torsion-resistant and tensile cable for mechanical joints, which comprises a cable core and an isolation layer and a sheath layer outside the cable core.

[0093] Specifically, the cable core is a stranded structure of one stress buffer wire core and twelve insulated wire cores, and the stranded pitch ratio is about 8 times. Moreover, on the cross section of the cable core, the twelve insulated wire cores are closely arranged in a ring around the stress buffer wire core.

[0094] In order to obtain excellent tensile properties and good structural creep properties of the cable core, and to provide sufficient stress buffering and deformation space for the corresponding insulated wire cores subjected to extrusion during bending and twisting, reduce the hard extrusion damage between adjacent insulated wire cores, the stress buffer wire core as the stranded center of the twelve insulated wire cores is formed by a filament polyester fiber bundle stranded structure with a bulkiness of about 30 cm³ / g and a compression recovery rate of about 85%, that is, the twelve insulated wire cores are closely arranged in a ring around the outer periphery of the stress buffer wire core.

[0095] Each insulated core is composed of a stranded conductor and an outer insulating layer. The stranded conductor is a stranded structure of multiple conductor units, and the stranded pitch ratio is about 10 times. Each conductor unit is a bundle stranded structure of multiple hard copper alloy wires (for example, tin copper alloy wires are preferred), and the diameter of the hard copper alloy wire is about 0.1 mm, and the tensile strength is about 750 MPa. The insulating layer is made of a polyolefin material with an elongation at break of about 680% and a tensile strength of about 25 MPa, which is extrusion-molded outside the stranded conductor. The average extrusion thickness of the insulating layer is about 0.33 mm. In the foregoing insulated core structure, the stranded conductor not only meets the technical requirements of electric conduction transmission, but also has good softness and high structural strength. The insulating layer has excellent anti-fracture and insulating properties. The final insulated core has good anti-fracture and anti-damage properties and high structural strength, effectively adapting to the working conditions of mechanical joints.

[0096] In order to further reliably adapt the insulated core to the working conditions of mechanical joints, reduce the extrusion friction force between adjacent insulated cores during bending and twisting, and enable the adjacent insulated cores to have a slippable performance, a layer of lubricating oil coating is applied outside the insulating layer of each insulated core. The lubricating oil coating is made of viscous silicone oil, which is formed in a full-coating structure on the outer surface of the corresponding insulated core. The average coating thickness of the lubricating oil coating on the outer surface of the corresponding insulated core is about 0.012 mm.

[0097] In order to make the above-mentioned cable core relatively round, and facilitate the extrusion molding of the outer sheath layer, a separation layer is wrapped outside the above-mentioned structural cable core. The separation layer is a three-layer overlapping wrapped structure of polytetrafluoroethylene turning band, and the overlapping wrapping rate of each layer is about 45%. The average thickness of the separation layer is about 0.1 mm.

[0098] In order to obtain good environmental resistance such as high and low temperature resistance, moisture resistance, oil resistance, and chemical corrosion resistance, the sheath layer is an extrusion structure of polyester type thermoplastic polyurethane elastomer. Moreover, while ensuring that the cable has good bending performance and radial compression resistance, a spiral skeleton layer is embedded in the sheath layer to effectively avoid stress concentration of the cable during small radius bending and twisting. The spiral skeleton layer is a spiral structure of 304 austenitic stainless steel wire with a diameter of about 0.5 mm, and the spiral pitch is about 16 times the diameter of the steel wire.

[0099] The cable with the above structure is prepared by the following process steps:

[0100] Step 1. First, use a wire bundling machine to bundle and twist the selected specification of hard copper alloy wires into conductor units in a concentric arrangement structure;

[0101] Then, use a rewinding machine to twist multiple conductor units together at a set stranded pitch ratio, and the twisting direction is opposite to the bundle twisting direction of the conductor units, to form a stranded conductor.

[0102] Step 1. Adopting a beam machine, long filament polyester fibers of selected specifications are twisted together to form a stress buffer core, ready for use;

[0103] Step 2. Adopting an extruder, polyolefin materials of selected specifications are extruded around the outside of the twisted conductor to form an insulation layer;

[0104] Wherein, the front section temperature of the extruder barrel for the insulation layer extrusion is about 140℃, the middle section temperature is about 150℃, the rear section temperature is about 170℃, the head temperature is about 170℃, and the die coefficient DBR of the extrusion die is about 1.2, and the stretching coefficient DDR is about 4.0;

[0105] Step 3. Adopting a rewinding machine, the insulation core of step 2 is subjected to 100% insulation detection;

[0106] And a sizing die is used to coat a layer of silicone oil on the surface of the insulation core with a set thickness to form a lubricating oil coating;

[0107] Step 4. Adopting a cabling machine, the stress buffer core prepared in step 1 is twisted together with the plurality of insulation cores prepared in step 3 in a concentric arrangement structure according to a set twisting pitch ratio;

[0108] In the process of cabling and twisting, a wrapping machine is used to wrap the selected polytetrafluoroethylene turning tape around the outside of the cable core with a set overlap rate;

[0109] Step 5. Adopting a steel wire spiral armoring machine, stainless steel wires of selected specifications are spiral armored on the outside of the cable core of step 4 in a cold working process according to a set pitch;

[0110] Step 6. First, a box-type hot air circulating dryer is used to dry the polyester thermoplastic polyurethane elastomer material, the baking temperature is about 110℃, and the baking time is about 3h;

[0111] Then, an extruder is used to extrude the selected polyester thermoplastic polyurethane elastomer material around the outside of the cable core of step 5 with a set thickness, and the extruded polyester thermoplastic polyurethane elastomer material fully covers the spiral steel wire of step 5 in the thickness direction;

[0112] Wherein, the front section temperature of the extruder barrel for the sheath layer extrusion is about 180℃, the middle section temperature is about 210℃, the rear section temperature is about 230℃, the head temperature is about 235℃, and the die coefficient DBR of the extrusion die is about 1.2, and the stretching coefficient DDR is about 4.0;

[0113] Finally, cooling and setting until the finished product.

[0114] The present application is a high-strength, bend-resistant, twist-resistant, and tensile-resistant cable for mechanical joints, which comprises a cable core and an isolation layer and a sheath layer outside the cable core.

[0115] Specifically, the cable core is a stranded structure of one stress buffer wire core and five insulated wire cores, and the stranded pitch ratio is about 6 times. Moreover, in the cross section of the cable core, the five insulated wire cores are closely arranged in a ring around the stress buffer wire core.

[0116] In order to obtain excellent tensile resistance of the cable core and good structural creep performance, and to provide sufficient stress buffer and deformation space for the corresponding insulated wire core under extrusion during bending and twisting, reduce the hard extrusion damage between adjacent insulated wire cores, the stress buffer wire core, which is the center of the five insulated wire cores, is formed by using a filament polyester fiber bundle stranded structure with a bulkiness of about 22 cm³ / g and a compression recovery rate of about 76%, that is, the five insulated wire cores are closely arranged in a ring around the outer periphery of the stress buffer wire core.

[0117] Each insulated wire core is composed of a stranded conductor and an insulating layer wrapped outside. The stranded conductor is a stranded structure of multiple conductor units, and the stranded pitch ratio is about 8 times. Each conductor unit is a bundle stranded structure of multiple hard copper alloy wires (for example, tin copper alloy wires are also preferred), and the diameter of the hard copper alloy wire is about 0.1 mm, and the tensile strength is about 700 MPa. The insulating layer is made of polyolefin material with an elongation at break of about 600% and a tensile strength of about 20 MPa, which is extrusion molded outside the stranded conductor. The average extrusion thickness of the insulating layer is about 0.25 mm. In the above-mentioned insulated wire core structure, the stranded conductor not only meets the technical requirements of electric conduction transmission, but also has good softness and high structural strength. The insulating layer has excellent anti-fracture and insulating properties. The final obtained insulated wire core has good anti-fracture and anti-damage properties, high structural strength, and effectively adapts to the working conditions of mechanical joints.

[0118] In order to further reliably adapt the insulated wire core to the working conditions of mechanical joints, reduce the extrusion friction force between adjacent insulated wire cores during bending and twisting, and provide a slippable performance between adjacent insulated wire cores, a layer of lubricating oil coating is applied outside the insulating layer of each insulated wire core. The lubricating oil coating is made of viscous silicone oil, which is formed in a full coverage coating structure on the outer surface of the corresponding insulated wire core. The average coating thickness of the lubricating oil coating on the outer surface of the corresponding insulated wire core is about 0.009 mm.

[0119] In order to make the above-mentioned cable core relatively round, and facilitate the extrusion molding of the external sheath layer, an isolation layer is wrapped outside the above-mentioned structural cable core. The isolation layer is a double-layer overlapping wrapped structure of polytetrafluoroethylene turning band, and the overlapping wrapping rate of each layer is about 50%. The average thickness of the isolation layer is about 0.07 mm.

[0120] In order to obtain good high and low temperature resistance, moisture resistance, oil resistance, chemical corrosion resistance and other environmental resistance, the sheath layer is an extrusion structure of polyester type thermoplastic polyurethane elastomer. Moreover, while ensuring that the cable has good bending performance and radial compression resistance, a spiral skeleton layer is embedded in the sheath layer to effectively avoid stress concentration of the cable during small radius bending and twisting. The spiral skeleton layer is a spiral structure of 316 austenitic stainless steel wire with a diameter of about 0.2 mm, and the spiral pitch is about 8 times the diameter of the steel wire.

[0121] The cable with the above structure is prepared by the following process steps:

[0122] Step 1. First, use a wire bundling machine to bundle and twist the selected specification of hard copper alloy wire into a conductor unit in a concentric arrangement structure;

[0123] Then, use a rewinding machine to twist together multiple conductor units at a set twisting pitch ratio, and the twisting direction is opposite to the bundling and twisting direction of the conductor unit, to form a twisted conductor;

[0124] Use a wire bundling machine to bundle and twist together the selected specification of long filament polyester fiber at a set requirement to form a stress buffer core for standby use;

[0125] Step 2. Use an extruder to extrude a selected specification of polyolefin material at a set thickness around the outside of the twisted conductor to form an insulation layer;

[0126] The temperature of the front section of the extruder barrel of the insulation layer extrusion is about 133°C, the temperature of the middle section is about 143°C, the temperature of the rear section is about 158°C, and the temperature of the head is about 163°C. The mold matching coefficient DBR of the extrusion mold is about 1.1, and the stretching coefficient DDR is about 2.0;

[0127] Step 3. Use a rewinding machine to perform 100% insulation detection on the insulation core of step 2;

[0128] And use a sizing die to coat a layer of silicone oil on the surface of the insulation core at a set thickness to form a lubricating oil coating;

[0129] Step 4. Use a cable forming machine to twist together the stress buffer core prepared in step 1 and the multiple insulation cores prepared in step 3 at a set twisting pitch ratio in a concentric arrangement structure;

[0130] During the cable twisting process, use a wrapping machine to wrap the selected polytetrafluoroethylene turning tape around the outside of the cable core at a set overlap rate;

[0131] Step 5. Use a steel wire spiral armor machine to spiral armor the selected specification of stainless steel wire around the outside of the cable core of step 4 in a cold working process at a set pitch;

[0132] Step 6. The polyester thermoplastic polyurethane elastomer material is dried by using a box-type hot air circulation dryer, the baking temperature is about 105℃, and the baking time is about 4h;

[0133] The selected polyester thermoplastic polyurethane elastomer material is extruded around the cable core outside in step 5 by using an extruder, and the extruded polyester thermoplastic polyurethane elastomer material fully covers the spiral steel wire in step 5 in the thickness direction;

[0134] The temperature of the front section of the extruder barrel of the sheath layer extrusion is about 165℃, the temperature of the middle section is about 195℃, the temperature of the rear section is about 222℃, and the temperature of the head is about 225℃, and the die matching coefficient DBR of the extrusion die is about 1.1, and the stretching coefficient DDR is about 3.5.

[0135] Finally, cooling and setting until the finished product.

[0136] Example 5

[0137] The present application is a high-strength, bend-resistant, torsion-resistant and tensile-resistant cable for mechanical joints, which comprises a cable core and an isolation layer and a sheath layer outside the cable core.

[0138] Specifically, the cable core is a stranded structure of one stress buffer wire core and three insulated wire cores, and the stranded pitch ratio is about 7 times. Moreover, on the cross section of the cable core, the three insulated wire cores are arranged in a ring around the stress buffer wire core.

[0139] In order to obtain excellent tensile properties and good structural creep properties of the cable core, and to provide sufficient stress buffering and deformation space for the corresponding insulated wire cores subjected to extrusion during bending and twisting, and to reduce the hard extrusion damage between adjacent insulated wire cores, the stress buffer wire core, which is the center of the three insulated wire cores, is formed by using a filament polyester fiber bundle stranded structure with a bulkiness of about 20cm³ / g and a compression recovery rate of about 75%, that is, the three insulated wire cores are arranged in a ring around the outer periphery of the stress buffer wire core.

[0140] Each insulated core is composed of a stranded conductor and an outer insulating layer. The stranded conductor is a stranded structure of multiple conductor units, and the stranded pitch ratio is about 9 times. Each conductor unit is a bundle stranded structure of multiple hard copper alloy wires (for example, tin copper alloy wires are also preferred), and the diameter of the hard copper alloy wire is about 0.1 mm, and the tensile strength is about 700 MPa. The insulating layer is made of a polyolefin material with an elongation at break of about 600% and a tensile strength of about 20 MPa, which is extrusion-molded outside the stranded conductor. The average extrusion thickness of the insulating layer is about 0.30 mm. In the foregoing insulated core structure, the stranded conductor not only meets the technical requirements of electric conduction transmission, but also has good softness and high structural strength. The insulating layer has excellent anti-fracture and insulating properties. The final insulated core has good anti-fracture and anti-damage properties, and high structural strength, effectively adapting to the working conditions of mechanical joints.

[0141] In order to further reliably adapt the insulated core to the working conditions of mechanical joints, reduce the extrusion friction force between adjacent insulated cores during bending and twisting, and enable the adjacent insulated cores to have a slippable performance, a layer of lubricating oil coating is applied outside the insulating layer of each insulated core. The lubricating oil coating is made of viscous silicone oil, which is formed in a full-coating structure on the outer surface of the corresponding insulated core. The average coating thickness of the lubricating oil coating on the outer surface of the corresponding insulated core is about 0.01 mm.

[0142] In order to make the above-mentioned cable core relatively round, and facilitate the extrusion molding of the outer sheath layer, a separation layer is wrapped outside the above-mentioned structural cable core. The separation layer is a double-layer overlapping wrapped structure of polytetrafluoroethylene turning band, and the overlapping wrapping rate of each layer is about 30%. The average thickness of the separation layer is about 0.06 mm.

[0143] In order to obtain good environmental resistance such as high and low temperature resistance, moisture resistance, oil resistance, chemical corrosion resistance, etc., the sheath layer is an extrusion structure of polyester type thermoplastic polyurethane elastomer. Moreover, while ensuring that the cable has good bending performance and radial compression resistance, a spiral skeleton layer is embedded in the sheath layer to effectively avoid stress concentration phenomenon of the cable during small radius bending and twisting. The spiral skeleton layer is a spiral structure of 316 austenitic stainless steel wire with a diameter of about 0.3 mm, and the spiral pitch is about 12 times the diameter of the steel wire.

[0144] The cable with the above structure is prepared by the following process steps:

[0145] Step 1. First, use a wire bundling machine to bundle and twist the selected specification of hard copper alloy wires into conductor units in a concentric arrangement structure;

[0146] Then, use a rewinding machine to twist multiple conductor units together at a set stranded pitch ratio, and the twisting direction is opposite to the bundle twisting direction of the conductor units, to form a stranded conductor.

[0147] Using a stranding machine, long filament polyester fibers of selected specifications are stranded together at a set requirement to form a stress buffer core for standby use;

[0148] Step 2. Using an extruder, polyolefin materials of selected specifications are extruded at a set thickness outside the stranded conductor to form an insulation layer;

[0149] Wherein, the front section temperature of the extruder barrel for the insulation layer extrusion is about 137℃, the middle section temperature is about 147℃, the rear section temperature is about 165℃, the head temperature is about 168℃, and the die matching coefficient DBR of the extrusion die is about 1.0, and the stretching coefficient DDR is about 3.5;

[0150] Step 3. Using a rewinding machine, the insulation core of step 2 is subjected to 100% insulation detection;

[0151] And a layer of silicone oil is coated on the surface of the insulation core at a set thickness using a sizing die to form a lubricating oil coating;

[0152] Step 4. Using a cabling machine, the stress buffer core prepared in step 1 is stranded together with the plurality of insulation cores prepared in step 3 in a concentric arrangement structure according to a set stranding pitch ratio;

[0153] In the process of cabling stranding, a selected polytetrafluoroethylene turning tape is wrapped around the outside of the cable core at a set overlap rate using a wrapping machine;

[0154] Step 5. Using a steel wire spiral armoring machine, stainless steel wires of selected specifications are spiral armored outside the cable core of step 4 in a cold working process according to a set pitch;

[0155] Step 6. First, using a box-type hot air circulating dryer, the polyester thermoplastic polyurethane elastomer material is subjected to drying treatment, the baking temperature is about 95℃, and the baking time is about 5h;

[0156] Then, using an extruder, the selected polyester thermoplastic polyurethane elastomer material is extruded at a set thickness outside the cable core of step 5, and the extruded polyester thermoplastic polyurethane elastomer material fully covers the spiral steel wire of step 5 in the thickness direction;

[0157] Wherein, the front section temperature of the extruder barrel for the sheath layer extrusion is about 175℃, the middle section temperature is about 205℃, the rear section temperature is about 228℃, the head temperature is about 232℃, and the die matching coefficient DBR of the extrusion die is about 1.0, and the stretching coefficient DDR is about 3.0;

[0158] Finally, cooling and setting until the finished product.

[0159] The above examples are only used to illustrate the present application, but not to limit it.

[0160] Although the present application has been described in detail with reference to the foregoing embodiments, it will be understood by those skilled in the art that various modifications can be made to the foregoing embodiments, or equivalents thereof, without departing from the spirit and scope of the application.

Claims

1. A high-strength bending-resistant cable for mechanical joints, comprising a cable core and a sheath layer (7) outside the cable core; characterized in that: the cable core is a stranded structure of a stress buffer core (4) and a plurality of insulated cores, and on the cross section of the cable core, the plurality of insulated cores are arranged in a ring around the stress buffer core (4), and the outer part of each insulated core is coated with a lubricating oil coating (3); the stress buffer core (4) is a filament polyester fiber bundle stranded structure with a bulkiness ≥20 cm³ / g and a compression recovery rate ≥75%.

2. The high-strength bending-resistant cable for mechanical joints according to claim 1, characterized in that: the number of insulated cores of the cable core is 3-12, and the stranded pitch ratio is 6-8 times.

3. The high-strength bending-resistant cable for mechanical joints according to claim 1 or 2, characterized in that: the insulated core is composed of a stranded conductor (1) and an insulating layer (2) wrapped outside; the stranded conductor (1) is a stranded structure of a plurality of conductor units, and the stranded pitch ratio is 8-10 times; each conductor unit is a bundle stranded structure of a plurality of hard copper alloy wires, and the diameter of the hard copper alloy wire is 0.1 mm, and the tensile strength is ≥700 MPa; the insulating layer (2) is an extrusion coating structure of a polyolefin material with an elongation at break ≥600% and a tensile strength ≥20 MPa.

4. The high-strength bending-resistant cable for mechanical joints according to claim 3, characterized in that: the average extrusion coating thickness of the insulating layer (2) is 0.28 mm±0.05 mm.

5. The high-strength bending-resistant cable for mechanical joints according to claim 1, characterized in that: the lubricating oil coating (3) is a coating structure of viscous silicone oil on the outer surface of the corresponding insulated core; the average coating thickness of the lubricating oil coating (3) is 0.01 mm±0.002 mm.

6. The high-strength bending-resistant cable for mechanical joints according to claim 1 or 2, characterized in that: the outside of the cable core is sequentially wrapped with an isolation layer (5) and a sheath layer (7) from the inside to the outside; the isolation layer (5) is at least one layer of overlapping wrapped structure of polytetrafluoroethylene turning band, and the thickness of the isolation layer (5) is 0.05-0.1 mm; the sheath layer (7) is an extrusion coating structure of polyester type thermoplastic polyurethane elastomer.

7. The high-strength bending-resistant cable for mechanical joints according to claim 6, characterized in that: the sheath layer (7) is inlaid with a spiral skeleton layer (6); the spiral skeleton layer (6) is a spiral structure of 304 austenitic stainless steel wire or 316 austenitic stainless steel wire with a diameter of 0.2-0.5 mm, and the spiral pitch is 8-16 times the diameter of the wire.

8. A method of manufacturing a high-strength, bend-resistant cable for use in a mechanical joint as claimed in any one of claims 1 to 7, characterized in that, The preparation method comprises the following process steps: Step 1. First, use a bundle machine to bundle and twist the selected specification of hard copper alloy wire into a conductor unit in a concentric arrangement structure; then use a rewinding machine to twist a plurality of conductor units together at a set stranded pitch ratio, and the twisting direction is opposite to the bundle twisting direction of the conductor unit, forming a stranded conductor; use a bundle machine to bundle and twist the selected specification of filament polyester fiber together to form a stress buffer core, ready for use; Step 2. Using an extruder, the polyolefin material of selected specification is extruded around the outside of the stranded conductor in a set thickness to form an insulation layer; Step 3. Using a rewinding machine, the insulated core of Step 2 is subjected to 100% insulation detection; and a sizing die is used to coat a layer of silicone oil on the surface of the insulated core in a set thickness to form a lubricating oil coating; Step 4. Using a cabling machine, the stress buffer core prepared in Step 1 and the plurality of insulated cores prepared in Step 3 are twisted together in a concentric arrangement according to a set twisting pitch ratio; In the process of cabling and twisting, a wrapping machine is used to wrap the selected polytetrafluoroethylene turning tape around the outside of the core in a set overlap ratio; Step 5. Using a steel wire spiral armoring machine, the stainless steel wire of selected specification is spiral armored around the outside of the core of Step 4 in a cold working process according to a set pitch; Step 6. Using an extruder, the selected polyester thermoplastic polyurethane elastomer material is extruded around the outside of the core of Step 5 in a set thickness, and the extruded polyester thermoplastic polyurethane elastomer material fully covers the spiral steel wire of Step 5 in the thickness direction; cooling, setting, until the finished product.

9. The preparation method of the high-strength bending-resistant cable for mechanical joints according to claim 8, characterized in that: In Step 2, the temperature of the front section of the extruder barrel is 130-140°C, the temperature of the middle section is 140-150°C, the temperature of the rear section is 150-170°C, the temperature of the head is 160-170°C, the die matching coefficient DBR of the extrusion die is 1.0-1.2, and the stretching coefficient DDR is 1.3-4.

0.

10. The preparation method of the high-strength bending-resistant cable for mechanical joints according to claim 8, characterized in that: In Step 6, before extrusion, the polyester thermoplastic polyurethane elastomer material is subjected to drying treatment using a box-type hot air circulating dryer, the baking temperature is 90-110°C, and the baking time is 3-6h; the temperature of the front section of the extruder barrel is 160-180°C, the temperature of the middle section is 190-210°C, the temperature of the rear section is 220-230°C, the temperature of the head is 215-235°C, the die matching coefficient DBR of the extrusion die is 1.0-1.2, and the stretching coefficient DDR is 2.5-4.0.

Images