Anti-vibration optical cable design method, anti-vibration optical cable and manufacturing method thereof

Abstract

The invention belongs to the technical field of special optical cables, and particularly discloses an anti-vibration optical cable design method, an anti-vibration optical cable and a manufacturing method thereof.The method comprises the steps that firstly, an initial sample optical cable is provided, and the excitation frequency of the optical cable use environment is obtained; then, the inherent frequency of the target optical cable is determined, and a frequency deviation exists between the inherent frequency of the target optical cable and the excitation frequency of the optical cable use environment; then, changing the material or / and the size of the outer sheath or / and the buffer layer of the initial sample optical cable, calculating whether the inherent frequency of the initial sample optical cable reaches the inherent frequency of the target optical cable, and repeatedly adjusting the material or / and the size of the outer sheath or / and the buffer layer of the initial sample optical cable until the inherent frequency of the initial sample optical cable reaches the expectation; and taking the changed initial sample optical cable as a target optical cable. The invention further provides a preparation method of the anti-vibration optical cable. By changing the inherent frequency of the optical cable, resonance between the optical cable and the groove box is avoided, and therefore the problem that an existing polarization maintaining optical cable is poor in anti-vibration effect can be effectively solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of special optical cables, and more specifically, relates to a vibration-resistant optical cable design method, a vibration-resistant optical cable and a manufacturing method thereof. Background Art

[0002] With the continuous development of the national high-voltage power grid project, there are multiple new and renovated converter stations on the transmission line every year. In the converter station, the optical CT and the signal collector are usually connected by a polarization-maintaining optical cable to transmit the information received by the optical CT to the signal collector. The existing polarization-maintaining optical cable is usually laid in the cable trough box. Since the existing conventional polarization-maintaining optical cable has poor vibration resistance, once the trough box is subjected to external impact or vibration, such as the falling of the fireproof board, the vibration caused by the mouse running on the trough box, etc., it will cause the polarization-maintaining optical cable in the trough box to vibrate together, so that the polarization-maintaining optical fiber vibrates with the optical cable, causing its transmission signal to be affected, and then false alarms will occur, causing serious consequences such as power line tripping and power outages.

[0003] At present, although the city company can achieve the effect of reducing the vibration of the optical cable by laying sponge pads in the trough box, this will greatly increase the laying cost and lay the sponge pads in the trough box will also greatly extend the construction period. Therefore, the market is in urgent need of a polarization-maintaining optical cable with good anti-vibration effect. Summary of the invention

[0004] In view of the defects of the prior art, the purpose of the present invention is to provide a vibration-resistant optical cable design method, a vibration-resistant optical cable and a manufacturing method thereof. By designing the optical cable structure and frequency, a vibration-resistant optical cable with a new structure is provided to avoid resonance between the optical cable and the trough box, thereby effectively solving the problem of poor vibration resistance of existing polarization-maintaining optical cables.

[0005] To achieve the above-mentioned purpose, according to one aspect of the present invention, a vibration-resistant optical cable design method is provided, first, an initial sample optical cable is provided, and the excitation frequency of the optical cable use environment is obtained; then, the natural frequency of the target optical cable is determined, and there is a frequency deviation between the natural frequency of the target optical cable and the excitation frequency of the optical cable use environment; then, based on the initial sample optical cable, the material and / or size of the outer sheath and / or buffer layer of the initial sample optical cable is changed, and it is calculated whether the changed natural frequency of the initial sample optical cable reaches the natural frequency of the target optical cable, and the material and / or size of the outer sheath and / or buffer layer of the initial sample optical cable is repeatedly adjusted until its natural frequency reaches the natural frequency of the target optical cable; finally, the changed initial sample optical cable is used as the target optical cable to complete the vibration-resistant optical cable design.

[0006] Furthermore, the natural frequency of the optical cable is calculated using the following formula:

[0007] In the above formula, is the natural frequency of the optical cable, n is the total amount of optical cable materials except the optical fiber, is the elastic modulus of material i in the optical cable, is the cross-sectional area of ​​material i, is the volume of the optical cable per unit length, is the damping coefficient, the damping coefficient The value range of is 1%~10%, m is the mass of the optical cable per unit length, and π is the circumference of the circle. Or, The material and / or size of the outer sheath and / or buffer layer of the initial sample optical cable are changed according to the following setting method, and the natural frequency of the optical cable is calculated according to the above formula at the same time. The setting method is: First change the material and / or size of the outer sheath. If the overall natural frequency of the optical cable does not reach the target natural frequency of the optical cable, then change the material and / or size of the multi-layer buffer layer to make the overall natural frequency of the optical cable reach the target natural frequency of the optical cable. When changing the material and size of the multi-layer buffer layer, change the material and / or size of one or more buffer layers in the order from the outside of the optical cable to the inside of the optical cable.

[0008] In the above invention concept, the type of material in the optical cable, the elastic modulus of the material, the volume of the optical cable per unit length, the total amount of the optical cable material and the mass of the optical cable per unit length can all affect its fixed frequency. As the main thing, the cable core is necessary, the structure of the cable core is relatively fixed, and the buffer layer unit and the outer sheath are convenient to design and change. The natural frequency of the optical cable is mainly changed by changing the buffer layer unit and the outer sheath.

[0009] According to a second aspect of the present invention, a vibration-resistant optical cable is provided, wherein there is a frequency deviation between the natural frequency of the optical cable and the excitation frequency of the use environment, and the optical cable comprises a cable core, a buffer layer unit, a reinforcement layer and an outer sheath, wherein the outer sheath is the outermost layer of the optical cable, the reinforcement layer has at least one layer, the buffer layer unit comprises a non-PTFE buffer layer, the non-PTFE buffer layer is located outside the cable core and close to the cable core, each reinforcement layer is located between the non-PTFE buffer layer and the outer sheath, and the structure, material and size of the buffer layer unit and / or the outer sheath are obtained by changing in sequence from the outside of the optical cable to the inside of the optical cable according to the frequency deviation requirement.

[0010] In the above invention, the non-PTFE buffer layer is made of PBT or TPU with a thickness of 0.1 mm to 0.5 mm. If the thickness is too large, it will affect the mechanical properties of the product, such as bending and torsion properties. If the thickness is too small, it will not achieve the expected protection effect on the optical fiber. PBT refers to polybutylene terephthalate, and TPU refers to thermoplastic polyurethane elastomer.

[0011] Furthermore, the buffer layer unit also includes a PTFE buffer layer, which is one or more layers, and the PTFE buffer layer is located between the non-PTFE buffer layer and the outer protective layer, and each reinforcement layer is located between the PTFE buffer layer and the outer protective layer. The PTFE buffer layer is made of PTFE and has a thickness of 0.5 mm to 2.0 mm. If the thickness is too small, the semi-sintered state of the PTFE buffer layer is difficult to achieve the expected buffering and vibration reduction effect. If the thickness is too large, the semi-sintered PTFE buffer layer is prone to cracking. PTFE refers to polytetrafluoroethylene.

[0012] Furthermore, the buffer layer unit also includes an additional non-PTFE buffer layer, which is located between the PTFE buffer layer and the outer sheath. When the PTFE buffer layer is multi-layered, multiple PTFE buffer layers are adjacent or non-adjacent, and at least one PTFE buffer layer is adjacent to the non-PTFE buffer layer. The material of the additional non-PTFE buffer layer is LSZH or TPU, and the thickness is 0.5mm~2.0mm. If the thickness is too small, it cannot play a buffering protection role, and if the thickness is too large, it will increase the overall size and production cost of the optical cable. ‌LSZH (Low Smoke Zero Halogen) refers to low-smoke halogen-free flame retardant material, and TPU is a polymer material with excellent physical and chemical properties and is widely used in various fields. ‌TPU is called Thermoplastic Polyurethane, which is called thermoplastic polyurethane elastomer in Chinese. It is a (AB)n type block linear polymer, A is a high molecular weight polyester or polyether, B is a diol containing 2~12 straight-chain carbon atoms, and the AB segments are connected by diisocyanate‌.

[0013] Furthermore, the buffer layer unit is a plurality of non-PTFE buffer layers, wherein there is a non-PTFE buffer layer located outside the cable core and adjacent to the cable core, and the remaining non-PTFE buffer layers are located between the non-PTFE buffer layer adjacent to the cable core and the outer sheath, and the reinforcement layer is also located between the non-PTFE buffer layer adjacent to the cable core and the outer sheath.

[0014] Furthermore, the PTFE buffer layer is a translucent PTFE layer, or the PTFE buffer layer includes a white first PTFE layer and a transparent second PTFE layer, wherein the first PTFE layer is embedded in the second PTFE layer, and the second PTFE layer accounts for more than 10% of the thickness of the PTFE buffer layer.

[0015] Among them, the material of the reinforcement layer is one or more of aramid fiber, PI fiber, glass fiber and PBO fiber, with a thickness of 0.1mm~1.0mm. Polyimide fiber (also known as PI fiber), also known as aromatic imide fiber, refers to the fiber containing aromatic imide in the molecular chain. PI fiber has good spinnability and can be made into textiles for various special occasions. ‌PBO fiber‌ is a high-performance fiber made of polyparapheneneBenzobisoxazol (PBO for short). PBO fiber has excellent properties such as high strength, high modulus, heat resistance, flame retardancy, etc., and is known as the "super fiber of the 21st century."

[0016] In the above inventive concept, the materials and thicknesses of the non-PTFE buffer layer, PTFE buffer layer, and additional non-PTFE buffer layer are limited. From a certain perspective, the size and material of the buffer layer unit are limited, providing a range and option for changing the natural frequency of the optical cable.

[0017] In fact, an armor layer can also be provided outside the outer sheath. The armor layer is armored by corrugated steel belts. The material of the outer sheath is LSZH with a thickness of ≥1.5 mm.

[0018] According to a third aspect of the present invention, there is also provided a method for preparing the vibration-resistant optical cable as described above, characterized in that it comprises the following steps: S1: According to the material and size of the optical cable structure determined by the vibration-resistant optical cable design method, determine the process parameters required for producing all buffer layers and the process parameters required for producing the outer sheath, so as to control the frequency deviation between the natural frequency of the optical cable and the excitation frequency of the use environment from the source. S2: First, a filler is applied around the optical fiber, and then, according to the determined process parameters of the non-PTFE buffer layer, a non-PTFE buffer layer is formed by extrusion outside the filler. While the non-PTFE buffer layer is being formed by extrusion, a reinforcement layer is added to the non-PTFE buffer layer simultaneously. S4: According to the determined process parameters for the additional non-PTFE buffer layer, an additional non-PTFE buffer layer is extruded outside the reinforcement layer. S5: Extrusion to form an outer protective layer.

[0019] Furthermore, it also includes step S3, which is to prepare a PTFE buffer layer outside the non-PTFE buffer layer by using an extrusion process. In the extrusion process, the PTFE buffer layer is extruded and coated at a set position, and then sintered at a semi-sintering temperature.

[0020] Wherein, the semi-sintering of PTFE means that the PTFE buffer layer is semi-sintered as a whole or the PTFE buffer layer is not sintered inside but sintered outside. When the PTFE buffer layer is semi-sintered as a whole, in the extrusion process, the temperature of the sintering furnace does not exceed the sintering temperature of the PTFE material, and the formed PTFE buffer layer has a lower hardness than the buffer layer formed by complete sintering and is not easy to crack. Alternatively, the semi-sintering of PTFE means that the PTFE buffer layer is not sintered inside but sintered outside. When the PTFE buffer layer is not sintered inside but sintered outside, in the extrusion process, along the routing direction of the optical fiber, the sintering furnace is divided into a heating zone and a cooling zone, wherein the temperature of the heating zone is the sintering temperature of the PTFE material, and the temperature of the cooling zone is lower than the sintering temperature of the PTFE material, so that the inside is not sintered but the outside is sintered, and the thickness of the PTFE of the fully sintered PTFE buffer layer is not less than 10% of the total thickness of the PTFE buffer layer.

[0021] Specifically, PTFE is extruded and coated at a set position, and sintered at a semi-sintering temperature. When the PTFE buffer layer is semi-sintered as a whole, the PTFE buffer layer as a whole presents a translucent state, and the maximum sintering temperature of the sintering furnace generally does not exceed 260°C. When a semi-sintering process is adopted in which the inside of the PTFE buffer layer is not sintered but the outside is sintered, the sintering temperature setting in the sintering process is gradually reduced along the routing direction and the temperature of the front half of the sintering furnace needs to be set to a normal sintering temperature. At the same time, a cooling device is provided in the back half of the sintering furnace to accelerate the reduction of the sintering temperature of the PTFE buffer layer, and the insulation time and production speed can be controlled at the same time to ensure the semi-sintering effect.

[0022] In the above invention concept, the semi-sintering of PTFE takes into account that the semi-sintered PTFE material is not completely plasticized and hardened, and has a certain buffering effect. On the other hand, the raw materials inside the PTFE buffer layer cannot withstand the temperature required for PTFE sintering. PTFE semi-sintering includes two methods: the PTFE buffer layer is semi-sintered as a whole and the PTFE buffer layer is not burned inside and burned outside. The method of burning the PTFE buffer layer inside and outside is preferred. The thickness of the PTFE buffer layer is completely sintered, and the thickness of the PTFE is not less than 10% of the total thickness of the PTFE buffer layer. At the same time, the PTFE buffer layer is not burned inside and burned outside. The process control requires that the sintering temperature, extrusion speed and product size of each zone are closely related. The temperature of the sintering furnace in the conventional sintering process increases successively along the routing direction. The sintering temperature setting in the present invention is exactly the opposite of the conventional temperature setting, and it gradually decreases along the routing direction.

[0023] Furthermore, the cable core includes a filler and multiple optical fibers, the multiple optical fibers have a space ratio of 40% to 70% in the non-PTFE buffer layer, the filler is filled around the multiple optical fibers to bond the multiple optical fibers together, the filler is an adhesive or fiber oil paste, and the multiple optical fibers are polarization-maintaining fibers.

[0024] In general, the above technical solution conceived by the present invention has the following technical advantages compared with the prior art: 1. The present invention provides a vibration-resistant optical cable design method, which changes the natural frequency of the optical cable so that there is a frequency deviation between it and the excitation frequency of the use environment, repeatedly adjusts the material and / or size of the outer sheath and / or buffer layer of the initial sample optical cable, selects appropriate optical cable materials and sizes according to actual vibration resistance needs, and thus develops an optical cable with a large difference from the actual vibration frequency, avoids resonance between the optical cable and the trough box, and can effectively solve the problem of poor vibration resistance of existing polarization-maintaining optical cables.

[0025] 2. The optical cable in the present invention comprises a cable core, a buffer layer unit, a reinforcement layer and an outer sheath, wherein the outer sheath is the outermost layer of the optical cable, the reinforcement layer has at least one layer, the buffer layer unit comprises a non-PTFE buffer layer, the non-PTFE buffer layer is located outside the cable core and close to the cable core, each reinforcement layer is located between the non-PTFE buffer layer and the outer sheath, and the material and / or size of the outer sheath and / or the buffer layer of the initial sample optical cable are changed to realize the selection and setting of the natural frequency of the optical cable.

[0026] 3. When preparing the optical cable of the present invention, a semi-sintering process is performed on PTFE, which can better take into account the processability and the temperature resistance of the inner and outer adjacent layers, and can also take into account the buffer resistance performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a schematic structural diagram of a vibration-resistant optical cable in an embodiment of the present invention; Figure 2 It is a structural schematic diagram of another vibration-resistant optical cable in an embodiment of the present invention.

[0028] Throughout the drawings, the same reference numerals are used to denote the same elements or structures, wherein: 1 is optical fiber, 2 is filler, 3 is non-PTFE buffer layer, 4 is PTFE buffer layer, 5 is reinforcement layer, 6 is additional non-PTFE buffer layer, 7 is armor layer, and 8 is outer sheath. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0030] In the description of the present invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0031] In addition, throughout this specification, "one embodiment", "one example" or similar language indicates that a particular feature, structure or characteristic described in conjunction with the embodiment is included in at least one embodiment of the present invention. Therefore, the phrase "in one embodiment" and similar language may, but do not necessarily, refer to the same embodiment.

[0032] In the description of this application, it should be understood that the terms "center", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or location relationships based on the attached Figure 1 The orientation or positional relationship shown is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0033] The present invention provides a vibration-resistant optical cable design method. Structurally, it includes a cable core, a buffer layer unit, a reinforcement layer and an outer sheath from the inside to the outside. The buffer layer unit has two structures. In the first type, the buffer layer unit includes a non-PTFE buffer layer, a PTFE buffer layer and an additional non-PTFE buffer layer distributed in sequence from the inside to the outside of the optical cable, and the reinforcement layer can be between the PTFE buffer layer and the additional non-PTFE buffer layer. In the second type, the buffer layer unit includes a non-PTFE buffer layer and an additional non-PTFE buffer layer distributed in sequence from the inside to the outside of the optical cable, and the reinforcement layer can be located between the non-PTFE buffer layer and the additional non-PTFE buffer layer, and there is no PTFE buffer layer. In actual engineering practice, the outer sheath is used as the outermost layer.

[0034] In one embodiment, the vibration-resistant optical cable is also provided with an armor layer, which serves as a secondary outer layer. Strictly speaking, the armor layer is optional and not necessary. Without the armor layer, the overall mechanical properties of the product will be affected. When the armor layer is provided, the armor layer must be a secondary outer layer and is adjacent to the additional non-PTFE buffer layer of the cable core. In addition to the non-PTFE buffer layer, there may be a PTFE buffer layer, or there may be no PTFE buffer layer, and only multiple non-PTFE buffer layers may be provided. The best position for other buffer layers is between the PTFE buffer layer and the armor layer. The position of the reinforcement layer is optional, and may be between the PTFE buffer layer and the additional non-PTFE buffer layer, or between the additional non-PTFE buffer layer and the armor layer.

[0035] Figure 1 is a schematic structural diagram of a vibration-resistant optical cable in an embodiment of the present invention. Figure 2 FIG. 1 is a schematic diagram of the structure of another vibration-resistant optical cable in an embodiment of the present invention. Combining the two figures, it can be seen that: Figure 1 The medium vibration-resistant optical cable comprises an optical fiber 1, a filler 2, a non-PTFE buffer layer 3, a PTFE buffer layer 4, a reinforcement layer 5, an additional non-PTFE buffer layer 6, an armor layer 7 and an outer sheath 8. Figure 2 Compared with medium vibration resistant optical cable Figure 1 The vibration-resistant optical cable lacks the PTFE buffer layer, but the other structures are the same.

[0036] The main function of the design of the buffer layer unit in the present invention is to buffer and reduce vibration and adjust the natural frequency of the entire optical cable by changing its own material and size. At the same time, the size of the outer sheath can also be changed to assist in adjusting the natural frequency of the entire optical cable. By changing the material and size of the outer sheath or / and the buffer layer unit, the natural frequency of the entire optical cable can be changed, and finally the resonance between the optical cable and the trough box can be avoided. The natural frequency of the entire optical cable is calculated using the following formula:

[0037] in, is the overall natural frequency of the optical cable, is the elastic modulus of material i in the optical cable, is the cross-sectional area of ​​material i, is the volume of the optical cable per unit length, n is the total amount of optical cable materials except the optical fiber, is the damping coefficient, m is the mass of the optical cable per unit length, and the damping coefficient The value range is 1%~10%.

[0038] In physics, the following formula is usually used to calculate the natural frequency of an undamped single object:

[0039] Among them, f nis the natural frequency of a single object, k is the material stiffness of a single object, and m is the mass of a single object.

[0040] From the above formula, we can see that the natural frequency of a single object is related to its stiffness and mass. However, for the structure of optical cables, first of all, optical cables are made of multiple materials, and the various materials have specific connection methods, and there is a certain damping effect between the connected parts. Therefore, the natural frequency of optical cables cannot be calculated using conventional calculation formulas. In order to theoretically calculate the natural frequency of optical cables, it is necessary to consider the damping effect between the materials inside the optical cable, that is, to consider the damping coefficient. At the same time, the material type and material amount related to the stiffness and quality of the optical cable must also be considered. Through the above vibration theory and test experiments, the calculation formula for the overall natural frequency of the optical cable provided by the present invention is obtained, and the above formula has been proven to be in line with the actual situation.

[0041] It should be noted that due to certain fluctuations in the production process of each process of the optical cable, there will be a reasonable deviation between the overall natural frequency of the optical cable calculated using the calculation formula described in the present invention and the actual natural frequency of the optical cable. This deviation is acceptable, and even if there is a deviation, it will not affect the technical effect to be achieved by the present invention.

[0042] In the present invention, the type of material in the optical cable, the elastic modulus of the material, the volume of the optical cable per unit length, the total amount of the optical cable material and the mass of the optical cable per unit length can all affect its fixed frequency. However, as the main thing, the cable core is necessary, the structural composition of the cable core is relatively fixed, the armor layer is certain, and only the buffer layer unit and the outer sheath are convenient to design and change. In fact, the natural frequency of the optical cable is changed mainly by changing the buffer layer unit and the outer sheath.

[0043] When adjusting the natural frequency of the entire optical cable, first change the material and size of the outer sheath. If the natural frequency of the entire optical cable does not reach the expected value, then change the material and size of the multi-layer buffer layer to make the natural frequency of the entire optical cable reach the expected value. When changing the material and size of the multi-layer buffer layer, change the material and size of one or more buffer layers in the order from the outside of the optical cable to the inside of the optical cable. In actual engineering, the thickness of the outer sheath can be changed according to the calculation results, and then the material can be changed. If the calculated natural frequency of the optical cable cannot match the frequency of the slot box in the use scenario after the thickness and material of the outer sheath are changed, and resonance may occur, then change the thickness and material of the additional non-PTFE buffer layer, and then calculate the natural frequency of the optical cable, and so on. In the entire process of adjusting the natural frequency of the optical cable, the outer sheath, additional non-PTFE buffer layer, PTFE buffer layer and non-PTFE buffer layer can all be used to change the size and material, and the size of the optical fiber, filler, reinforcement layer and armor layer material does not change.

[0044] In one embodiment of the present invention, the non-PTFE buffer layer is made of PBT or TPU with a thickness of 0.1mm~0.5mm. If the thickness is too large, it will affect the mechanical properties of the product, such as bending and torsion performance. If the thickness is too small, the expected protection effect on the optical fiber cannot be achieved. The material of the PTFE buffer layer is PTFE with a thickness of 0.5mm~2.0mm. If the thickness is too small, the semi-sintered state of the PTFE buffer layer is difficult to achieve the expected buffering and vibration reduction effect. If the thickness is too large, the semi-sintered PTFE buffer layer is prone to cracking. The material of the additional non-PTFE buffer layer is LSZH or TPU with a thickness of 0.5mm~2.0mm. If the thickness is too small, it cannot play a buffering and protective role. If the thickness is too large, the overall size and production cost of the optical cable will be increased. The outer sheath is made of LSZH with a thickness of ≥1.5mm. The material and thickness of the non-PTFE buffer layer, PTFE buffer layer, additional non-PTFE buffer layer and outer sheath are limited. From a certain perspective, the size and material of the buffer layer unit are limited, providing a range and choice for changing the natural frequency of the optical cable.

[0045] In another embodiment of the present invention, the material of the reinforcement layer is one or more of aramid fiber, PI fiber, glass fiber and PBO fiber, and the thickness is 0.1mm~1.0mm. The reason for selecting such thickness is that on the one hand, the reinforcement layer can provide sufficient tensile strength, and on the other hand, the fiber material can provide better buffering effect. In theory, the thicker the reinforcement layer, the better the buffering effect, but considering the actual production cost, the reinforcement layer is generally not too thick. The armor layer is armored with corrugated steel belt. The duty ratio of the optical fiber in the non-PTFE buffer layer is 40%~70%. Such a duty ratio has the advantage that the optical fiber has enough free space for movement in the non-PTFE buffer layer to avoid the optical fiber being squeezed in the non-PTFE buffer layer. The cable core includes a filler and multiple optical fibers, or the cable core includes a filler and an optical fiber. The filler is filled around the optical fiber to bond the optical fiber into one. Bonding to form a whole can reduce vibration interference. The filler is an adhesive or fiber oil paste. The optical fiber can be a polarization-maintaining optical fiber. In order to distinguish, it can also be made into a colored optical fiber.

[0046] The present invention also provides a method for preparing the vibration-resistant optical cable as described above, which comprises the following steps: S1: According to the material and size of the optical cable structure determined by the vibration-resistant optical cable design method, determine the process parameters required for producing all buffer layers and the process parameters required for producing the outer sheath, so as to control the frequency deviation between the natural frequency of the optical cable and the excitation frequency of the use environment from the source. S2: First, a filler is applied around the optical fiber, and then, according to the determined process parameters of the non-PTFE buffer layer, a non-PTFE buffer layer is formed by extrusion outside the filler. While the non-PTFE buffer layer is being formed by extrusion, a reinforcement layer is added to the non-PTFE buffer layer simultaneously. S4: According to the determined process parameters for the additional non-PTFE buffer layer, an additional non-PTFE buffer layer is extruded outside the reinforcement layer. S5: Extrusion to form an outer protective layer.

[0047] In one embodiment, preparing the vibration-resistant optical cable comprises the following steps: S1: According to the material and size of the optical cable structure determined by the vibration-resistant optical cable design method, the process parameters required for producing all buffer layers and the process parameters required for producing the outer sheath are determined to control the frequency deviation between the natural frequency of the optical cable and the excitation frequency of the environment in which it is used from the source. S2: First, apply filler around the optical fiber, and then extrude the non-PTFE buffer layer outside the filler according to the determined non-PTFE buffer layer process parameters. When the filler is an adhesive: the viscosity of the adhesive is 3000±500mpa*s; the hardness of the adhesive after curing is less than Shao A40, so as to reduce the stress on the optical fiber and bond multiple optical fibers together. The operating time of the adhesive is greater than 1 hour to ensure the production process time window. While the non-PTFE buffer layer is extruded, a reinforcement layer is added to the non-PTFE buffer layer simultaneously.

[0048] The selection of adhesive is very critical. It must be able to bond multiple optical fibers into one, but it must not be too hard to introduce stress to the optical fiber and affect the optical performance. In addition, the process performance must be considered and the viscosity must be moderate. After many tests, considering the process performance, optical performance of the optical fiber, cost and other factors, combined with experience, the adhesive with a viscosity of 3000±500mpa*s and a hardness less than Shore A40 after curing was selected. Its composition is silicone.

[0049] S3: This step is to prepare a PTFE buffer layer outside the non-PTFE buffer layer by using an extrusion process. In the extrusion process, the PTFE buffer layer is extruded and coated at a set position, and then sintered at a semi-sintering temperature. The PTFE semi-sintering is the semi-sintering of the PTFE buffer layer as a whole or the PTFE buffer layer is not sintered inside but sintered outside. When the PTFE buffer layer is semi-sintered as a whole, during the extrusion process, the temperature of the sintering furnace does not exceed the sintering temperature of the PTFE material, and the formed PTFE buffer layer is less hard than the buffer layer formed by complete sintering and is not easy to crack, or, When the inside of the PTFE buffer layer is sintered without being sintered but the outside is sintered, in the extrusion process, along the routing direction of the optical fiber, the sintering furnace is divided into a heating zone and a cooling zone, wherein the temperature of the heating zone is the sintering temperature of the PTFE material, and the temperature of the cooling zone is lower than the sintering temperature of the PTFE material, so that the inside is not sintered but the outside is sintered, and the thickness of the PTFE of the completely sintered PTFE buffer layer is not less than 10% of the total thickness of the PTFE buffer layer.

[0050] S4: According to the determined process parameters for the additional non-PTFE buffer layer, an additional non-PTFE buffer layer is extruded outside the reinforcement layer. S5: Extrusion to form an outer protective layer.

[0051] In actual engineering, PTFE is extruded and coated at a set position, and then sintered at a semi-sintering temperature. When the PTFE buffer layer is semi-sintered as a whole, the PTFE buffer layer is translucent as a whole. At this time, the maximum sintering temperature of the sintering furnace generally does not exceed 260°C. When the semi-sintering process is used in which the PTFE buffer layer is not sintered inside but sintered outside, the thickness of the PTFE buffer layer is not less than 10% of the total thickness of the PTFE buffer layer. In this sintering process, the sintering temperature setting is gradually reduced along the routing direction and the temperature of the front half of the sintering furnace needs to be set to the normal sintering temperature. At the same time, a cooling device is provided to accelerate the reduction of the sintering temperature of the PTFE buffer layer. The cooling device can simultaneously control the insulation time and the production speed to ensure the semi-sintering effect. The thickness of the PTFE buffer layer is not less than 10% of the total thickness of the PTFE buffer layer. This is because the thickness of the fully sintered PTFE is too small and the unsintered part is prone to cracking.

[0052] The temperature of the sintering furnace is not higher than the sintering temperature of the PTFE material (corresponding to the overall semi-sintering at this time), and the formed PTFE buffer layer is less hard than the buffer layer formed by complete sintering and is not easy to crack. Or in the pushing process, the optical fiber is laid out along the routing, and the sintering furnace is divided into a heating zone and a cooling zone, wherein the temperature of the heating zone is the sintering temperature of the PTFE material, and the temperature of the cooling zone is lower than the sintering temperature of the PTFE material. At this time, the inside is not sintered but the outside is sintered, so the unsintered part forms a buffer layer, which can produce a buffering effect, and the sintered part can protect the unsintered part to prevent the unsintered part from cracking. When the PTFE buffer layer is a translucent PTFE layer. Or when the outside is sintered and the inside is not sintered, the PTFE buffer layer includes a white PTFE layer (that is, the unsintered part) and a transparent outer PTFE layer (that is, the sintered part), wherein the inner PTFE layer is located inside the outer PTFE layer, and the thickness of the outer PTFE layer accounts for more than 10% of the total PTFE buffer layer.

[0053] In the actual production process of the factory, the manufacturing method of the new vibration-resistant structure special optical cable with three buffer layers includes the following steps: S1. Production of colored optical fiber; Set the appropriate curing temperature and select the appropriate mold to color the optical fiber surface; S2, production of non-PTFE buffer layer; The plurality of colored optical fibers produced by the above S1 are mounted on a pay-off frame, and a coating device is set between the optical fiber pay-off frame and the extruder to coat the filler, set a suitable extrusion temperature, select a suitable mold, set a reasonable pay-off and take-up line tension and production speed, and then start to produce a non-PTFE buffer layer and simultaneously coat the filler. The filler material is an adhesive, and in order to fill the adhesive fully, the inner diameter of the outlet die on the coating device is not less than the inner diameter of the extrusion die core.

[0054] S3, producing PTFE buffer layer; The semi-finished products produced by S2 are installed on the wire rack, and the appropriate pushing mold is selected, the appropriate sintering temperature is set, the reasonable wire tension and production speed are set, and the production of PTFE buffer layer begins.

[0055] S4, producing an additional non-PTFE buffer layer; The semi-finished product produced by S3 is installed on the pay-off stand, and a suitable extrusion die is selected, a suitable extrusion temperature is set, a reasonable pay-off and take-up line tension and production speed are set, and the production of an additional non-PTFE buffer layer begins. In this step, the PTFE buffer layer and the additional non-PTFE buffer layer are provided with a reinforcement layer, and the reinforcement layer material is fiber, and the setting method is straight or weaving. The weaving or straightening of the reinforcement layer is completed synchronously during the production of the additional non-PTFE buffer layer. In terms of the process, it seems that the production of the reinforcement layer and the preparation of the additional non-PTFE buffer layer are carried out simultaneously. In fact, from a more subtle perspective, the reinforcement layer is first woven or straightened before the additional non-PTFE buffer layer can be prepared outside the reinforcement layer.

[0056] S5, producing outer sheath; Install the semi-finished products produced by S4 on the pay-off rack, select the appropriate extrusion die, set the appropriate extrusion temperature, set the reasonable pay-off and take-up wire tension and production speed, and start producing the outer sheath.

[0057] In fact, a step of preparing an armor layer may be added before step S5, and the armor layer serves as the secondary outer layer of the optical cable.

[0058] The preparation method of the novel vibration-resistant special optical cable having only two buffer layers comprises the following steps: S1. Production of colored optical fiber; Set the appropriate curing temperature and select the appropriate mold to color the optical fiber surface; S2, production of non-PTFE buffer layer; The multiple colored optical fibers produced by S1 are installed on the pay-off rack, a filling device is set between the optical fiber pay-off rack and the extruder, the appropriate extrusion temperature is set, the appropriate mold is selected, and the reasonable pay-off and take-up tension and production speed are set, and then the non-PTFE buffer layer is produced and the plastic filling is applied. The filling material is fiber oil paste, and the filling is required to be full and free of bubbles.

[0059] S3, producing an additional non-PTFE buffer layer; The semi-finished product produced by S2 is installed on the pay-off stand, a suitable extrusion die is selected, a suitable extrusion temperature is set, a reasonable pay-off and take-up line tension and production speed are set, and the production of an additional non-PTFE buffer layer begins. In this step, the non-PTFE buffer layer and the additional non-PTFE buffer layer are provided with a reinforcing layer, and the reinforcing layer material is fiber, and the setting method is straight or weaving. The weaving or straightening of the reinforcing layer is completed synchronously during the production of the additional non-PTFE buffer layer. In terms of the process, it seems that the production of the reinforcing layer and the preparation of the additional non-PTFE buffer layer are carried out simultaneously. In fact, from a more subtle perspective, the reinforcing layer is first woven or straightened before the additional non-PTFE buffer layer can be prepared outside the reinforcing layer.

[0060] S4, produce outer sheath; Install the semi-finished products produced by S3 on the pay-off rack, select the appropriate extrusion die, set the appropriate extrusion temperature, set the reasonable pay-off and take-up wire tension and production speed, and start producing the outer sheath.

[0061] The material of the PTFE buffer layer is one or more of aramid fiber, PI fiber, glass fiber and PBO fiber.

[0062] In fact, a step of preparing an armor layer may be added before step S4, and the armor layer serves as the secondary outer layer of the optical cable.

[0063] In the above two methods, the materials and sizes of the non-PTFE buffer layer, the additional non-PTFE buffer layer and the outer sheath can be selected according to the theoretical calculation results of the overall natural frequency calculation formula of the optical cable and the vibration resistance requirements. The adjustment method is from outside to inside, that is, if the overall natural frequency of the optical cable needs to be adjusted after calculation according to the calculation formula, it is preferred to adjust the material and size of the outer sheath. If further adjustment is required, the additional non-PTFE buffer layer is adjusted. If further adjustment is required, the non-PTFE buffer layer inside the additional non-PTFE buffer layer is adjusted.

[0064] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A vibration-resistant optical cable design method, characterized in that: Firstly, an initial sample optical cable is provided, and the excitation frequency of the optical cable use environment is obtained; Next, determining the natural frequency of the target optical cable, wherein there is a frequency deviation between the natural frequency of the target optical cable and the excitation frequency of the optical cable use environment; Then, based on the initial sample optical cable, the material and / or size of the outer sheath and / or the buffer layer of the initial sample optical cable are changed, and it is calculated whether the natural frequency of the changed initial sample optical cable reaches the natural frequency of the target optical cable, and the material and / or size of the outer sheath and / or the buffer layer of the initial sample optical cable are repeatedly adjusted until its natural frequency reaches the natural frequency of the target optical cable; Finally, the changed initial sample optical cable is used as the target optical cable to complete the vibration-resistant optical cable design.

2. The method according to claim 1, characterized in that The natural frequency of the optical cable is calculated using the following formula: In the above formula, is the natural frequency of the optical cable, n is the total amount of optical cable materials except the optical fiber, is the elastic modulus of material i in the optical cable, is the cross-sectional area of ​​material i, is the volume of the optical cable per unit length, is the damping coefficient, the damping coefficient The value range is 1%~10%, m is the mass of the optical cable per unit length, π is the circumference of a circle, or, The material and / or size of the outer sheath and / or buffer layer of the initial sample optical cable are changed according to the following setting method, and the natural frequency of the optical cable is calculated according to the above formula at the same time. The setting method is: First change the material and / or size of the outer sheath. If the overall natural frequency of the optical cable does not reach the target natural frequency of the optical cable, then change the material and / or size of the multi-layer buffer layer to make the overall natural frequency of the optical cable reach the target natural frequency of the optical cable. When changing the material and size of the multi-layer buffer layer, change the material and / or size of one or more buffer layers in the order from the outside of the optical cable to the inside of the optical cable.

3. A vibration-resistant optical cable, characterized in that: It includes a cable core, a buffer layer unit, a reinforcement layer and an outer sheath, wherein the outer sheath is the outermost layer of the optical cable, and the reinforcement layer has at least one layer. The buffer layer unit comprises a non-PTFE buffer layer, which is located outside the cable core and close to the cable core. Each reinforcement layer is located between the non-PTFE buffer layer and the outer sheath, and, There is a frequency deviation between the natural frequency of the optical cable and the excitation frequency of the operating environment.

4. A vibration-resistant optical cable as claimed in claim 3, characterized in that: The buffer layer unit also includes a PTFE buffer layer, which is one layer or multiple layers. The PTFE buffer layer is located between the non-PTFE buffer layer and the outer protective layer, and each reinforcement layer is located between the PTFE buffer layer and the outer protective layer.

5. A vibration-resistant optical cable as claimed in claim 4, characterized in that: The buffer layer unit also includes an additional non-PTFE buffer layer, which is located between the PTFE buffer layer and the outer sheath. When the PTFE buffer layer is multi-layered, the multiple PTFE buffer layers are adjacent or non-adjacent, and at least one PTFE buffer layer is adjacent to a non-PTFE buffer layer.

6. A vibration-resistant optical cable as claimed in claim 3, characterized in that: The buffer layer unit is a plurality of non-PTFE buffer layers, wherein there is a non-PTFE buffer layer located outside the cable core and adjacent to the cable core, and the remaining non-PTFE buffer layers are located between the non-PTFE buffer layer adjacent to the cable core and the outer sheath, and the reinforcement layer is also located between the non-PTFE buffer layer adjacent to the cable core and the outer sheath.

7. A vibration-resistant optical cable as claimed in claim 4, characterized in that: The PTFE buffer layer is a translucent PTFE layer, or the PTFE buffer layer includes a white first PTFE layer and a transparent second PTFE layer, wherein the first PTFE layer is embedded in the second PTFE layer, and the second PTFE layer accounts for more than 10% of the thickness of the PTFE buffer layer.

8. A method for preparing a vibration-resistant optical cable as claimed in any one of claims 3 to 7, characterized in that: It includes the following steps: S1: According to the material and size of the optical cable structure determined by the vibration-resistant optical cable design method, determine the process parameters required for producing all buffer layers and the process parameters required for producing the outer sheath, so as to control the frequency deviation between the natural frequency of the optical cable and the excitation frequency of the use environment from the source. S2: First, a filler is applied around the optical fiber, and then, according to the determined process parameters of the non-PTFE buffer layer, a non-PTFE buffer layer is formed by extrusion outside the filler. While the non-PTFE buffer layer is being formed by extrusion, a reinforcement layer is added to the non-PTFE buffer layer simultaneously. S4: According to the determined process parameters for the additional non-PTFE buffer layer, an additional non-PTFE buffer layer is extruded outside the reinforcement layer. S5: Extrusion to form an outer protective layer.

9. The method according to claim 8, characterized in that It also includes step S3, which is to prepare a PTFE buffer layer outside the non-PTFE buffer layer by using an extrusion process. In the extrusion process, the PTFE buffer layer is extruded and coated at a set position, and then sintered at a semi-sintering temperature.

10. The method according to claim 9, characterized in that PTFE semi-sintering means that the PTFE buffer layer is semi-sintered as a whole or the inside of the PTFE buffer layer is not sintered but the outside is sintered. When the PTFE buffer layer is semi-sintered as a whole, during the extrusion process, the temperature of the sintering furnace does not exceed the sintering temperature of the PTFE material, and the formed PTFE buffer layer is less hard than the buffer layer formed by complete sintering and is not easy to crack, or, When the inside of the PTFE buffer layer is sintered without being sintered but the outside is sintered, in the extrusion process, along the routing direction of the optical fiber, the sintering furnace is divided into a heating zone and a cooling zone, wherein the temperature of the heating zone is the sintering temperature of the PTFE material, and the temperature of the cooling zone is lower than the sintering temperature of the PTFE material, so that the inside is not sintered but the outside is sintered, and the thickness of the PTFE of the completely sintered PTFE buffer layer is not less than 10% of the total thickness of the PTFE buffer layer.

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