A method of designing a vibration-resistant optical cable, a vibration-resistant optical cable and a method of manufacturing the same

Abstract

The application belongs to the technical field of special optical cable, and particularly discloses a design method of an anti-vibration optical cable, the anti-vibration optical cable and a manufacturing method thereof. First, an initial sample optical cable is provided, and an excitation frequency of an optical cable use environment is obtained. Then, an inherent frequency of a target optical cable is determined, and there is a frequency deviation between the inherent frequency of the target optical cable and the excitation frequency of the optical cable use environment. Then, the material and / or size of the outer sheath and / or the buffer layer of the initial sample optical cable is changed, and whether the inherent frequency reaches the inherent frequency of the target optical cable is calculated. The material and / or size of the outer sheath and / or the buffer layer of the initial sample optical cable is repeatedly adjusted until the inherent frequency reaches an expectation, and the changed initial sample optical cable is used as the target optical cable. The application further provides a preparation method of the above anti-vibration optical cable. By changing the inherent frequency of the optical cable, resonance between the optical cable and a groove box is avoided, so that the problem of poor anti-vibration effect of the existing polarization maintaining optical cable can be effectively solved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of special optical cable, more particularly, relates to a vibration-resistant optical cable design method, a vibration-resistant optical cable and a manufacturing method thereof. BACKGROUND

[0002] With the continuous development of national high-voltage power grid projects, there are new construction and transformation requirements of multiple converter stations on the power transmission line every year. In the converter station, the polarization-maintaining optical cable is usually used to connect the optical CT and the signal collector to transmit the information received by the optical CT to the signal collector. The existing polarization-maintaining optical cable is usually laid in a cable slot box. Since the existing conventional polarization-maintaining optical cable has poor vibration resistance, once the slot box is impacted or vibrated by external factors such as the falling of fireproof plates or the running of mice on the slot box, the polarization-maintaining optical cable in the slot box will vibrate together, and the polarization-maintaining optical fiber will vibrate together with the optical cable, which will affect the transmission signal and cause false alarms, resulting in serious consequences such as power line tripping and power failure.

[0003] At present, although the sponge pad can be laid in the slot box to reduce the vibration of the optical cable in the city company, this will greatly increase the laying cost, and laying the sponge pad in the slot box will also greatly prolong the construction period, so there is an urgent need for a polarization-maintaining optical cable with good vibration resistance in the market. SUMMARY

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

[0005] To achieve the above-mentioned purpose, according to one aspect of the present application, 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 or / and size of the outer protective layer or / and buffer layer of the initial sample optical cable is changed, and whether the natural frequency of the changed initial sample optical cable reaches the natural frequency of the target optical cable is calculated. The material or / and size of the outer protective layer or / and buffer layer of the initial sample optical cable is repeatedly adjusted until the 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, and the vibration-resistant optical cable design is completed.

[0006] Further, the natural frequency of the optical cable is calculated by the following formula:

[0007]

[0008] In the above formula, is the inherent frequency of the optical cable, n is the total number of the optical cable materials other than the optical fiber, is the elastic modulus of the material i in the optical cable, is the cross-sectional area of the material i, is the volume of the optical cable per unit length, is the damping coefficient, the damping coefficient is in the range of 1% to 10%, m is the mass of the optical cable per unit length, and π is the circular constant. Alternatively,

[0009] The material and / or size of the outer sheath and / or the buffer layer of the initial sample optical cable is changed in the following manner, and the inherent frequency of the optical cable is calculated according to the above formula, and the manner is as follows:

[0010] First, the material and / or size of the outer sheath is changed, and if the overall inherent frequency of the optical cable does not reach the target inherent frequency of the optical cable, then the material and / or size of the multi-layer buffer layer is changed to make the overall inherent frequency of the optical cable reach the target inherent frequency of the optical cable. When the material and size of the multi-layer buffer layer are changed, the material and / or size of one or more buffer layers is changed in order from the outside of the optical cable to the inside of the optical cable.

[0011] In the above inventive 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 number of the optical cable materials, and the mass of the optical cable per unit length all affect the inherent frequency. As the main, the cable core is necessary, the structural composition of the cable core is relatively fixed, the buffer layer unit and the outer sheath are convenient to design and change, and the inherent frequency of the optical cable is mainly changed by changing the buffer layer unit and the outer sheath.

[0012] According to a second aspect of the present application, there is provided an anti-vibration optical cable, the inherent frequency of the optical cable and the excitation frequency of the use environment have a frequency deviation, which comprises a cable core, a buffer layer unit, a reinforcing layer and an outer sheath, wherein the outer sheath is the outermost layer of the optical cable, the reinforcing 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 reinforcing 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 changed in order from the outside of the optical cable to the inside of the optical cable according to the requirement of the frequency deviation.

[0013] In the above inventive concept, the material of the non-PTFE buffer layer is PBT or TPU, and the thickness is 0.1mm to 0.5mm. If the thickness is too large, it will affect the mechanical properties of the product, such as bending and torsion performance, and 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.

[0014] Further, the buffer layer unit further comprises a PTFE buffer layer, the PTFE buffer layer 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 reinforcing layer is located between the PTFE buffer layer and the outer protective layer. The material of the PTFE buffer layer is PTFE, and the thickness is 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 damping effect, and if the thickness is too large, the semi-sintered PTFE buffer layer is easy to crack. PTFE refers to polytetrafluoroethylene.

[0015] Further, the buffer layer unit further comprises an additional non-PTFE buffer layer, the additional non-PTFE buffer layer is located between the PTFE buffer layer and the outer protective layer, when the PTFE buffer layer is multiple layers, the multiple PTFE buffer layers are adjacent or not 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 of the optical cable and the production cost. LSZH (Low Smoke Zero Halogen) refers to low smoke and halogen-free flame-retardant material, TPU is a high molecular material with excellent physical and chemical properties, and is widely used in various fields. TPU stands for 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 AB segments are connected by diisocyanate.

[0016] Further, the buffer layer unit is multiple non-PTFE buffer layers, one non-PTFE buffer layer is 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 protective layer, and the reinforcing layer is also located between the non-PTFE buffer layer adjacent to the cable core and the outer protective layer.

[0017] Further, the PTFE buffer layer is a translucent PTFE layer, or the PTFE buffer layer comprises 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.

[0018] The material of the reinforcing layer is one or more of aramid fiber, PI fiber, glass fiber and PBO fiber, and the thickness is 0.1mm-1.0mm. The polyimide fiber (also known as PI fiber) refers to the fiber containing aramid in the molecular chain. The PI fiber has good spinnability and can be made into various textiles for special occasions. PBO fiber is a high-performance fiber made of poly (p-phenylene benzobisoxazole) (PBO) material. PBO fiber has excellent properties such as high strength, high modulus, heat resistance and flame resistance, and is known as the "super fiber of the 21st century".

[0019] In the above inventive concept, the material and thickness of the non-PTFE buffer layer, the PTFE buffer layer and the additional non-PTFE buffer layer are limited, which limits the size and material of the buffer layer unit from a certain angle, and provides a range of changing the inherent frequency of the optical cable and selection.

[0020] In fact, an armor layer can also be provided outside the outer protective layer, the armor layer is armored by corrugated steel strip, and the material of the outer protective layer is LSZH, and the thickness is greater than or equal to 1.5mm.

[0021] According to the third aspect of the present application, a method for manufacturing the anti-vibration optical cable is also provided, which comprises the following steps:

[0022] S1: according to the material and size of the optical cable structure determined by the anti-vibration optical cable design method, determine the process parameters required for producing all the buffer layers and the process parameters required for producing the outer protective layer, so as to control the frequency deviation between the inherent frequency of the optical cable and the excitation frequency of the used environment from the source,

[0023] S2: first, coat the filler around the optical fiber, then according to the determined non-PTFE buffer layer process parameters, extrude the non-PTFE buffer layer outside the filler, and at the same time, increase the reinforcing layer in the non-PTFE buffer layer,

[0024] S4: according to the determined additional non-PTFE buffer layer process parameters, extrude the additional non-PTFE buffer layer outside the reinforcing layer,

[0025] S5: extruding the outer protective layer.

[0026] Further, it further comprises step S3, which is to prepare the PTFE buffer layer outside the non-PTFE buffer layer by using a push extrusion process. In the push extrusion process, the PTFE buffer layer is extruded and coated at a set position, and then sintered at a semi-sintering temperature.

[0027] The PTFE semi-sintering is the whole PTFE buffer layer semi-sintering or the internal PTFE buffer layer non-sintering and external sintering. When the whole PTFE buffer layer is semi-sintered, the temperature of the sintering furnace in the pushing process is not more than the sintering temperature of the PTFE material, and the hardness of the PTFE buffer layer formed is smaller than that of the buffer layer formed by complete sintering, and the PTFE buffer layer is not easy to crack. Alternatively, the internal PTFE buffer layer is non-sintered and the external PTFE buffer layer is sintered. When the internal PTFE buffer layer is non-sintered and the external PTFE buffer layer is sintered, in the pushing process, along the running 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 internal PTFE buffer layer is non-sintered and the external PTFE buffer layer is sintered. The thickness of the completely sintered PTFE of the PTFE buffer layer is not less than 10% of the total thickness of the PTFE buffer layer.

[0028] Specifically, the PTFE is extruded and coated at a set position, and sintered at a semi-sintering temperature. When the whole PTFE buffer layer is semi-sintered, the whole PTFE buffer layer appears semi-transparent, and the maximum sintering temperature of the sintering furnace is generally not more than 260 DEG C. When the internal PTFE buffer layer is non-sintered and the external PTFE buffer layer is sintered, the sintering temperature in the sintering process is gradually reduced along the running direction, and the temperature of the front half of the sintering furnace needs to be set to the normal sintering temperature, and the rear half of the sintering furnace is provided with a cooling device to accelerate the reduction of the sintering temperature of the PTFE buffer layer, and the holding time and the production speed can be controlled at the same time to ensure the semi-sintering effect.

[0029] In the above inventive concept, on the one hand, the semi-sintered PTFE material is not completely plasticized and hardened, and has a certain buffering effect, and on the other hand, the raw materials in the internal PTFE buffer layer cannot withstand the temperature required by the PTFE sintering. The PTFE semi-sintering includes whole PTFE buffer layer semi-sintering and internal PTFE buffer layer non-sintering and external sintering, and the internal PTFE buffer layer non-sintering and external sintering is preferred. The thickness of the completely sintered PTFE of the PTFE buffer layer is not less than 10% of the total thickness of the PTFE buffer layer, and the internal PTFE buffer layer non-sintering and external sintering process requires that the sintering temperature of each zone, the pushing speed and the product size are closely related. The sintering furnace temperature in the conventional sintering process is sequentially increased along the running direction, and the sintering temperature setting in the present application is just opposite to the conventional temperature setting, and is gradually reduced along the running direction.

[0030] Further, the cable core includes a filler and a plurality of optical fibers, the occupancy ratio of the plurality of optical fibers in the non-PTFE buffer layer is 40% to 70%, and the filler is filled around the plurality of optical fibers to bond the plurality of optical fibers into one body. The filler is an adhesive or a fiber oil paste, and the plurality of optical fibers are polarization maintaining optical fibers.

[0031] Overall, compared with the prior art, the above technical solutions conceived by the present application mainly have the following technical advantages:

[0032] 1. The present application provides an anti-vibration optical cable design method, which changes the natural frequency of the optical cable, so that there is a frequency deviation between the natural frequency and the excitation frequency of the use environment. The material and size of the outer sheath or / and the buffer layer of the initial sample optical cable are repeatedly adjusted, and appropriate optical cable material and size are selected according to actual anti-vibration needs, so as to formulate an optical cable with a large difference from the actual vibration frequency, thereby avoiding resonance between the optical cable and the slot box, and effectively solving the problem of poor anti-vibration effect of the existing polarization maintaining optical cable.

[0033] 2. The optical cable in the present application comprises a cable core, a buffer layer unit, a reinforcing layer and an outer sheath. The outer sheath is the outermost layer of the optical cable, the reinforcing layer has at least one layer, and the buffer layer unit comprises a non-PTFE buffer layer located outside the cable core and close to the cable core. Each reinforcing layer is located between the non-PTFE buffer layer and the outer sheath. The material and size of the outer sheath or / and 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.

[0034] 3. When preparing the optical cable of the present application, a semi-sintering process is performed on PTFE, which can better balance the process performance and the temperature resistance of the adjacent layers on the inside and outside, and also consider the buffer resistance performance. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 is a structure schematic diagram of an anti-vibration optical cable in an embodiment of the present application;

[0036] Figure 2 is a structure schematic diagram of another anti-vibration optical cable in an embodiment of the present application.

[0037] In all the drawings, the same reference signs are used to represent the same elements or structures, wherein:

[0038] 1 is an optical fiber, 2 is a filler, 3 is a non-PTFE buffer layer, 4 is a PTFE buffer layer, 5 is a reinforcing layer, 6 is an additional non-PTFE buffer layer, 7 is an armor layer, and 8 is an outer sheath. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solutions and advantages of the present application more clear and explicit, the present application is further described in detail below in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application.

[0040] In the description of the application, it is to be understood that the terms "first", "second", "third" and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and embodiments of the application are meant to encompass one or another of the terms and every combination of elements replacing the terms in this manner.

[0041] In addition, throughout the specification, "one embodiment", "one example", or similar language means that a particular feature, structure, or characteristic described in connection with this embodiment is included in at least one embodiment of the application. Therefore, the phrases "in one embodiment" and similar language, as used throughout this application, do not necessarily refer to the same embodiment.

[0042] In the description of the application, it is to be understood that the terms "center", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, indicate the orientation or position relationship based on the drawings shown, and are only for the purpose of facilitating the description of the application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the application. Figure 1

[0043] The application provides an anti-vibration optical cable design method. In structure, it comprises, from inside to outside, a cable core, a buffer layer unit, a reinforcing layer, and an outer protective layer. The structure of the buffer layer unit has two kinds. In the first kind, the buffer layer unit comprises a non-PTFE buffer layer, a PTFE buffer layer, and an additional non-PTFE buffer layer distributed in sequence along the direction from the inside to the outside of the optical cable. The reinforcing layer can be between the PTFE buffer layer and the additional non-PTFE buffer layer. In the second kind, the buffer layer unit comprises a non-PTFE buffer layer and an additional non-PTFE buffer layer distributed in sequence along the direction from the inside to the outside of the optical cable. The reinforcing layer can be 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 protective layer is the outermost layer.

[0044] ​In one embodiment, the anti-vibration optical cable is also provided with an armor layer as a secondary outer layer. The armor layer is optional and not necessary in strict sense. Without the armor layer, the overall mechanical performance of the product will be affected. When the armor layer is provided, the armor layer must be a secondary outer layer and adjacent to the additional non-PTFE buffer layer of the cable core. The non-PTFE buffer layer can be a PTFE buffer layer or can be free of the PTFE buffer layer. Only a plurality of non-PTFE buffer layers are provided. The optimal position of the other buffer layer is between the PTFE buffer layer and the armor layer. The position of the reinforcing layer can be selected. The reinforcing layer can 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.

[0045] Figure 1 is a structural schematic diagram of an anti-vibration optical cable in an embodiment of the present application, Figure 2 is a structural schematic diagram of another anti-vibration optical cable in an embodiment of the present application. As can be seen from the two diagrams, Figure 1 The anti-vibration optical cable in the embodiment includes an optical fiber 1, a filler 2, a non-PTFE buffer layer 3, a PTFE buffer layer 4, a reinforcing layer 5, an additional non-PTFE buffer layer 6, an armor layer 7, and an outer protective layer 8. Figure 2 The anti-vibration optical cable in the embodiment is different from the anti-vibration optical cable in Figure 1 The anti-vibration optical cable in the embodiment is different from the anti-vibration optical cable in

[0046] The main function of the buffer layer unit in the present application is to buffer and reduce vibration and adjust the overall natural frequency of the optical cable by changing the material and size of the buffer layer unit. The size of the outer protective layer can also be changed to assist in adjusting the overall natural frequency of the optical cable. The material and size of the outer protective layer and / or the buffer layer unit are changed to change the overall natural frequency of the optical cable, which ultimately avoids resonance between the optical cable and the slot box. The overall natural frequency of the optical cable is calculated using the following formula:

[0047]

[0048] wherein, is the overall natural frequency of the optical cable, is the elastic modulus of the material i in the optical cable, is the cross-sectional area of the material i, is the volume of the optical cable per unit length, n is the total number of materials in the optical cable excluding the optical fiber, is the damping coefficient, m is the mass of the optical cable per unit length, and the damping coefficient The value of the damping coefficient is in the range of 1% to 10%.

[0049] In physics, the natural frequency of a single object without damping is usually calculated using the following formula:

[0050]

[0051] wherein, fn is the inherent frequency of the single object, k is the material stiffness of the single object, and m is the mass of the single object.

[0052] It can be seen from the above formula that the inherent frequency of the single object is related to its stiffness and mass. However, for the optical cable structure, firstly, the optical cable is composed of multiple materials, and there is a specific connection mode between the various materials, and there is a certain damping effect between the connected parts, so the inherent frequency of the optical cable cannot be calculated by the conventional calculation formula. In order to theoretically calculate the inherent frequency of the optical cable, the damping effect between the materials inside the optical cable must be considered, that is, the damping coefficient , and the types of materials related to the stiffness and mass of the optical cable, the amount of materials, etc. must also be considered. Through the above vibration theory and test experiments, the optical cable overall inherent frequency calculation formula provided by the present application is obtained, and the above formula is consistent with the actual situation after demonstration.

[0053] It should be particularly pointed out that since there is a certain fluctuation in the production process of each process of the optical cable, there will be a reasonable deviation between the optical cable overall inherent frequency calculated by the calculation formula of the present application and the actual inherent frequency of the optical cable, which is acceptable, and even if there is a deviation, it does not affect the technical effect to be achieved by the present application.

[0054] In the present application, the types of materials in the optical cable, the elastic modulus of the materials, the volume of the optical cable per unit length, the total amount of the optical cable materials, and the mass of the optical cable per unit length can all affect its fixed frequency, but as the main, the cable core is necessary, the structure of the cable core is relatively fixed, the armor layer is certain, only the buffer layer unit and the outer protective layer can be designed and changed, in fact, the inherent frequency of the optical cable is mainly changed by changing the buffer layer unit and the outer protective layer.

[0055] When adjusting the inherent frequency of the optical cable as a whole, first change the material and size of the outer protective layer, if the overall inherent frequency of the optical cable does not reach the expectation, then change the material and size of the multi-layer buffer layer, so that the overall inherent frequency of the optical cable reaches the expectation, when changing the material and size of the multi-layer buffer layer, the material and size of one layer or more layers of the buffer layer are changed in order from the outside of the optical cable to the inside of the optical cable. In actual engineering, the thickness of the outer protective layer can be changed first according to the calculation result, and then the material can be changed, if the thickness and material of the outer protective layer are changed, the inherent frequency of the optical cable obtained by calculation cannot be matched with the frequency of the slot box in the use scenario, and resonance may occur, then the thickness and material of the additional non-PTFE buffer layer are changed, the inherent frequency of the optical cable is calculated again, and so on. In the whole process of adjusting the inherent frequency of the optical cable, the outer protective layer, the additional non-PTFE buffer layer, the PTFE buffer layer and the non-PTFE buffer layer can be used to change the size and material, and the material and size of the optical fiber, the filler, the reinforcing layer and the armor layer are not changed.

[0056] In one embodiment of the present application, the material of the non-PTFE buffer layer is PBT or TPU, and the thickness is 0.1mm~0.5mm. If the thickness is too large, the mechanical properties of the product, such as bending and torsion, will be affected. 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, and the thickness is 0.5mm~2.0mm. If the thickness is too small, the semi-sintered state of the PTFE buffer layer cannot achieve the expected buffering and damping 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, and the thickness is 0.5mm~2.0mm. If the thickness is too small, the buffering protection effect cannot be achieved. If the thickness is too large, the overall size of the optical cable and the production cost will increase. The material of the outer protective layer is LSZH, and the thickness is ≥1.5mm. The material and thickness of the non-PTFE buffer layer, the PTFE buffer layer, the additional non-PTFE buffer layer, and the outer protective layer are limited, which also limits the size and material of the buffer layer unit from a certain angle, and provides a range and selection for changing the natural frequency of the optical cable.

[0057] In another embodiment of the present application, the material of the reinforcing 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 choosing such thickness is that on the one hand the reinforcing layer can provide sufficient tensile strength, and on the other hand the fiber material can provide better buffering effect. In theory, the thicker the reinforcing layer, the better the buffering effect. However, considering the actual production cost, the reinforcing layer generally cannot be too thick. The armor layer is armored by corrugated steel belt. The space occupied by the optical fiber in the non-PTFE buffer layer is 40%~70%. Such space occupied ratio has the advantage that the optical fiber has enough free space in the non-PTFE buffer layer to avoid being squeezed. The cable core includes a filler and a plurality of optical fibers, or a filler and one optical fiber. The filler is filled around the optical fiber to bond the optical fiber into one body, and the bonding forms a whole to reduce vibration interference. The filler is 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.

[0058] The present application also provides a method for preparing the anti-vibration optical cable as described above, which comprises the following steps:

[0059] S1: According to the material and size of the optical cable structure determined by the anti-vibration optical cable design method, determine the process parameters required for producing all the buffer layers and the process parameters required for producing the outer protective layer, so as to control the frequency deviation between the natural frequency of the optical cable and the excitation frequency of the environment used from the source,

[0060] S2: first apply a filler around the optical fiber, then extrude a non-PTFE buffer layer outside the filler according to the determined non-PTFE buffer layer process parameters, and simultaneously increase the reinforcing layer inside the non-PTFE buffer layer while extruding the non-PTFE buffer layer,

[0061] S4: extrude an additional non-PTFE buffer layer outside the reinforcing layer according to the determined additional non-PTFE buffer layer process parameters,

[0062] S5: extrude the outer protective layer.

[0063] In one embodiment, the preparation of the anti-vibration optical cable includes the following steps:

[0064] S1: determine the process parameters required for producing all the buffer layers and the process parameters required for producing the outer protective layer according to the materials and dimensions of the cable structure determined by the anti-vibration optical cable design method, so as to control the frequency deviation between the natural frequency of the cable and the excitation frequency of the environment used from the source,

[0065] S2: first apply a filler around the optical fiber, then extrude a non-PTFE buffer layer outside the filler according to the determined non-PTFE buffer layer process parameters, and simultaneously increase the reinforcing layer inside the non-PTFE buffer layer while extruding the non-PTFE buffer layer.

[0066] The selection of the adhesive is very critical, it not only needs to bond multiple optical fibers into one, but also cannot be too hard to introduce stress to the optical fibers and affect the optical performance, and it also needs to consider the process performance, the viscosity needs to 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±500 mpa*s and a hardness less than Shore A40 after curing is selected, and its composition is organic silicon.

[0067] S3: this step is to prepare a PTFE buffer layer outside the non-PTFE buffer layer by using a push extrusion process, in the push 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 whole semi-sintering of the PTFE buffer layer or internal non-sintering and external sintering of the PTFE buffer layer,

[0068] When the PTFE buffer layer is whole semi-sintered, in the push extrusion process, the temperature of the sintering furnace does not exceed the sintering temperature of the PTFE material, the PTFE buffer layer formed has smaller hardness than the buffer layer formed by complete sintering, and is not easy to crack, or,

[0069] When the PTFE buffer layer is not sintered inside and sintered outside, in the pushing process, along the running 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 and the outside is sintered, and the thickness of the completely sintered PTFE of the PTFE buffer layer is not less than 10% of the total thickness of the PTFE buffer layer.

[0070] S4: extruding the additional non-PTFE buffer layer outside the reinforcing layer according to the determined additional non-PTFE buffer layer process parameters,

[0071] S5: extruding the outer protective layer.

[0072] 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 sintered as a whole, the PTFE buffer layer appears semi-transparent, and the highest sintering temperature of the sintering furnace is generally not more than 260°C. When the PTFE buffer layer is sintered inside and sintered outside, the thickness of the completely sintered PTFE of the PTFE buffer layer is not less than 10% of the total thickness of the PTFE buffer layer, and the sintering temperature in this sintering process is gradually reduced along the running direction, and the temperature of the first half of the sintering furnace needs to be set to the normal sintering temperature, and a cooling device is provided to accelerate the reduction of the sintering temperature of the PTFE buffer layer. The cooling device can control the holding time and the production speed at the same time to ensure the semi-sintering effect. The thickness of the completely sintered PTFE of the PTFE buffer layer is not less than 10% of the total thickness of the PTFE buffer layer, because the thickness of the completely sintered PTFE is too small, and the unsintered part is easy to crack.

[0073] The temperature of the sintering furnace is not more than the sintering temperature of the PTFE material (at this time, the whole is semi-sintered), and the hardness of the PTFE buffer layer formed is smaller than that of the buffer layer formed by complete sintering, and it is not easy to crack. Or in the pushing process, along the running 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, at this time, the inside is not sintered and the outside is sintered, therefore, the unsintered part forms a buffer layer, which can produce a buffering effect, and the sintered part can protect the unsintered part, preventing the unsintered part from cracking, and the PTFE buffer layer is a semi-transparent PTFE layer. Or when the outside is sintered and the inside is not sintered, the PTFE buffer layer includes a white PTFE layer (i.e. the unsintered part) and a transparent outer PTFE layer (i.e. the sintered part), wherein the inner PTFE layer is located inside the outer PTFE layer, and the outer PTFE layer accounts for more than 10% of the total thickness of the PTFE buffer layer.

[0074] In the actual production process of the factory, the manufacturing method of the new anti-vibration structure special optical cable with three-layer buffer layer comprises the following steps:

[0075] S1, producing colored optical fibers;

[0076] Setting appropriate curing temperature, selecting appropriate mold for optical fiber surface coloring;

[0077] S2, producing non-PTFE buffer layer;

[0078] The above S1 produces a plurality of colored optical fibers on the pay-off rack, sets a coating device between the optical fiber pay-off rack and the extruder for coating the filler, sets appropriate extrusion temperature, selects appropriate mold and sets reasonable pay-off and take-up tension and production speed, and then starts to produce non-PTFE buffer layer and synchronously coats the filler. The material of the filler is adhesive, and in order to make the adhesive filling full, the inner diameter size of the outlet die on the coating device is not less than the inner diameter size of the extrusion die core.

[0079] S3, producing PTFE buffer layer;

[0080] The semi-finished product produced by S2 is loaded on the pay-off rack, appropriate extrusion mold is selected, appropriate sintering temperature is set, reasonable pay-off and take-up tension and production speed are set, and the production of PTFE buffer layer is started.

[0081] S4, producing additional non-PTFE buffer layer;

[0082] The semi-finished product produced by S3 is loaded on the pay-off rack, appropriate extrusion mold is selected, appropriate extrusion temperature is set, reasonable pay-off and take-up tension and production speed are set, and the production of additional non-PTFE buffer layer is started. In this step, the PTFE buffer layer and the additional non-PTFE buffer layer are provided with a reinforcing layer, and the reinforcing layer is made of fiber, which is arranged in a straight or woven manner. The weaving or straightening of the reinforcing layer is completed synchronously with the production of the additional non-PTFE buffer layer. Although 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 point of view, the reinforcing layer is first woven or straightened, and then the additional non-PTFE buffer layer is prepared outside the reinforcing layer.

[0083] S5, producing outer protective layer;

[0084] The semi-finished product produced by S4 is loaded on the pay-off rack, appropriate extrusion mold is selected, appropriate extrusion temperature is set, reasonable pay-off and take-up tension and production speed are set, and the production of outer protective layer is started.

[0085] In fact, a step of preparing an armor layer can be added before step S5, and the armor layer serves as a secondary outer layer of the optical cable.

[0086] The preparation method of the new anti-vibration structure special optical cable with two buffer layers comprises the following steps:

[0087] S1, producing colored optical fibers;

[0088] Setting appropriate curing temperature, selecting appropriate mold for optical fiber surface coloring;

[0089] S2, producing non-PTFE buffer layer;

[0090] The above S1 produces a plurality of colored optical fibers on the pay-off rack, sets the filling device between the optical fiber pay-off rack and the extruder, sets the appropriate extrusion temperature, selects the appropriate mold, sets the reasonable take-up and pay-off tension and production speed, and then starts to produce the non-PTFE buffer layer and the plastic filler. The material of the filler is fiber oil paste, and the filling requires fullness without air bubbles.

[0091] S3, producing additional non-PTFE buffer layer;

[0092] The semi-finished product produced by S2 is placed on the pay-off rack, the appropriate extrusion mold is selected, the appropriate extrusion temperature is set, the reasonable take-up and pay-off tension and production speed are set, and the production of the additional non-PTFE buffer layer is started. 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 is made of fiber and is placed directly or woven. The weaving or direct placement of the reinforcing layer is completed synchronously with the production of the additional non-PTFE buffer layer. Although it seems that the reinforcing layer and the additional non-PTFE buffer layer are produced at the same time, in fact, from a more subtle point of view, the reinforcing layer is first woven or placed directly, and then the additional non-PTFE buffer layer is prepared outside the reinforcing layer.

[0093] S4, producing outer protective layer;

[0094] The semi-finished product produced by S3 is placed on the pay-off rack, the appropriate extrusion mold is selected, the appropriate extrusion temperature is set, the reasonable take-up and pay-off tension and production speed are set, and the production of the outer protective layer is started.

[0095] The material of the PTFE buffer layer is one or more of aramid fiber, PI fiber, glass fiber and PBO fiber.

[0096] In fact, a step of preparing an armor layer can be added before step S4, and the armor layer serves as the secondary outer layer of the optical cable.

[0097] In the above two methods, the material and size of the non-PTFE buffer layer, the additional non-PTFE buffer layer and the outer protective layer can be selected according to the theoretical calculation results of the overall natural frequency calculation formula of the optical cable and the anti-vibration requirement, and the adjustment mode is from the outside to the inside, that is, after the calculation according to the calculation formula, the overall natural frequency of the optical cable needs to be adjusted, the material and size of the outer protective sleeve are preferably adjusted, if further adjustment is needed, the additional non-PTFE buffer layer is adjusted, and if further adjustment is needed, the non-PTFE buffer layer inside the additional non-PTFE buffer layer is adjusted.

[0098] Those skilled in the art will easily understand that the above description is only the preferred embodiment of the present application, and is not used to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for designing a vibration-resistant optical cable, characterized in that, 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 or / and buffer layer of the initial sample optical cable is 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 or / and buffer layer of the initial sample optical cable is repeatedly adjusted until the natural frequency of the initial sample optical cable reaches the natural frequency of the target optical cable; finally, the changed initial sample optical cable is taken as the target optical cable, and the vibration-resistant optical cable design is completed, the natural frequency of the optical cable is calculated by the following formula: In the above formula, is the inherent frequency of the optical cable, n is the total number of optical cable materials other than optical fibers, 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 is in the range of 1%~10%, m is the mass of the optical cable per unit length, π is the circular constant, or, The material and / or size of the outer sheath or / and buffer layer of the initial sample optical cable is changed in the following setting manner, and the natural frequency of the optical cable is calculated at the same time, the setting manner is: first, the material and / or size of the outer sheath is changed, if the overall natural frequency of the optical cable does not reach the natural frequency of the target optical cable, then the material and / or size of the multi-layer buffer layer is changed, so that the overall natural frequency of the optical cable reaches the natural frequency of the target optical cable, when the material and / or size of the multi-layer buffer layer is changed, the material and / or size of one layer or multiple layers of the buffer layer is changed in the order from the outside of the optical cable to the inside of the optical cable.

2. A vibration resistant optical cable characterized by, It comprises a cable core, a buffer layer unit, a reinforcing layer and an outer sheath, wherein the outer sheath is the outermost layer of the optical cable, the reinforcing 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 reinforcing 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 use environment.

3. A ruggedized fiber optic cable of claim 2 wherein, The buffer layer unit further comprises 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 sheath, and each reinforcing layer is located between the PTFE buffer layer and the outer sheath.

4. A ruggedized fiber optic cable of claim 3 wherein, The buffer layer unit further comprises an additional non-PTFE buffer layer, which is located between the PTFE buffer layer and the outer sheath, When the PTFE buffer layer is multiple layers, the multiple PTFE buffer layers are adjacent or not adjacent, and at least one PTFE buffer layer is adjacent to the non-PTFE buffer layer.

5. A ruggedized fiber optic cable of claim 2 wherein, The buffer layer unit is multiple non-PTFE buffer layers, one non-PTFE buffer layer is 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 reinforcing layer is also located between the non-PTFE buffer layer adjacent to the cable core and the outer sheath.

6. A ruggedized fiber optic cable of claim 3 wherein, The PTFE buffer layer is a semi-transparent PTFE layer, or the PTFE buffer layer comprises a white first PTFE layer and a transparent second PTFE layer, wherein the first PTFE layer is embedded inside the second PTFE layer, and the second PTFE layer accounts for more than 10% of the thickness of the PTFE buffer layer.

7. A method of manufacturing an anti-torque cable as claimed in any one of claims 2 to 6, characterised in that, It comprises the following steps: S1: according to the material and size of the cable structure determined by the anti-vibration optical cable design method, determine the process parameters required for producing all the buffer layers and the process parameters required for producing the outer protective layer, so as to control the frequency deviation between the inherent frequency of the optical cable and the excitation frequency of the environment used from the source, S2: first coat the filler around the optical fiber, then extrude the non-PTFE buffer layer outside the filler according to the determined non-PTFE buffer layer process parameters, and simultaneously increase the reinforcing layer in the non-PTFE buffer layer while extruding the non-PTFE buffer layer, S4: according to the determined additional non-PTFE buffer layer process parameters, extrude the additional non-PTFE buffer layer outside the reinforcing layer, S5: extruding the outer protective layer.

8. The method of claim 7, wherein, It also includes step S3, which is to prepare a PTFE buffer layer outside the non-PTFE buffer layer using a push-pull process. In the push-pull process, the PTFE buffer layer is extruded and coated at a set position, and then sintered at a semi-sintering temperature.

9. The method of claim 8, wherein, PTFE semi-sintering is the whole semi-sintering of the PTFE buffer layer or the internal non-sintering and external sintering of the PTFE buffer layer, When the whole PTFE buffer layer is semi-sintered, the temperature of the sintering furnace in the push-pull process does not exceed the sintering temperature of the PTFE material, and the hardness of the PTFE buffer layer formed is smaller than that of the buffer layer formed by complete sintering, and it is not easy to crack, or When the PTFE buffer layer is internally unsintered and externally sintered, in the push-pull process, along the 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 internal is not sintered and the external is sintered, and the thickness of the completely sintered PTFE of the PTFE buffer layer is not less than 10% of the total thickness of the PTFE buffer layer.

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