A layered air-blown microcable

Abstract

This application relates to a stranded air-blown microcable, including an outer sheath. Multiple optical units are stranded within the outer sheath, centered on a reinforcing member. The surface of the outer sheath has spirally distributed textures of a designed size. These textures are numerous and uniformly distributed around the circumference of the stranded air-blown microcable's cross-section. A portion of the textures is symmetrically arranged with another portion about the diameter of the reinforcing member as an axis of symmetry. The stranded air-blown microcable has a linearity factor β ≤ 0.02, a dynamic friction coefficient less than 0.3, and an overall unit density ρ between 0.0005 and 0.0015 g / mm³. The symmetrical and uniform arrangement of these textures ensures that the airflow generated by the air-blowing process acts evenly on the outer side of the outer sheath, increasing the air-blowing distance. Simultaneously, because the linearity factor and dynamic friction coefficient are less than the designed values, these two factors work together to reduce linear changes during the air-blowing process and increase the air-blowing force. Furthermore, specific limitations on the texture size and the overall unit density of the optical cable ultimately increase the air-blowing distance on routes with many bends.

Description

Technical Field

[0001] This application relates to the field of optical cable manufacturing technology, and in particular to a stranded air-blown microcable. Background Technology

[0002] With the vigorous development of fiber-to-the-home and metropolitan area networks, the application of stranded air-blown microcables is becoming more and more widespread. However, with the scarcity of urban land and pipeline resources, stranded air-blown microcables are facing a variety of complex routes. Routes with many bends will require better air-blowing performance to meet the laying requirements.

[0003] In related technologies, the air-blowing performance of stranded air-blowing microcables is affected by various factors, including the surface texture of the optical cable, the coefficient of friction, the cable weight, outer diameter, and straightness. Current industry patents primarily focus on the shape of the surface texture of the optical cable, altering the airflow by changing the texture shape, but do not limit the size of the texture. Extensive experimental data reveals that texture size (depth and size), straightness factor, cable weight, and outer diameter all significantly influence the air-blowing performance of the optical cable, which is reflected in the air-blowing distance.

[0004] Therefore, how to design air-blown optical cables to increase the air-blowing distance in order to ensure smooth cable laying is an urgent problem to be solved. Summary of the Invention

[0005] This application provides a stranded air-blown microcable to solve the problem in related technologies that simply changing the texture shape of the air-blown optical cable is insufficient to meet the air-blowing distance requirements of routes with many bends.

[0006] In a first aspect, a stranded air-blown microcable is provided, which includes an outer sheath, and multiple optical units are stranded together with a reinforcing member as the center inside the outer sheath. The surface of the outer sheath is provided with spirally distributed patterns, and the number of patterns is multiple and they are evenly distributed on the circumference of the cross-section of the stranded air-blown microcable; a portion of the patterns and another portion of the patterns are symmetrically arranged with the diameter of the reinforcing member as the axis of symmetry.

[0007] The straightness factor β of the stranded air-blown microcable is ≤0.02.

[0008] In some embodiments, the lowest point of the texture is located on an extension line; the extension line is a straight line formed by the intersection of two adjacent optical units and the center point of the stranded air-blown microcable.

[0009] The range of the texture depth d is:

[0010]

[0011] The width of the texture

[0012] Wherein, the vertical distance d between the lowest point of the texture and the highest point of the outer sheath is the texture depth, the lateral distance L between the peaks at the left and right ends of the texture is the texture width; h is the thickness of the outer sheath, D1 is the diameter of the optical unit, D0 is the diameter of the reinforcing member; n is the number of optical units, or n is the sum of the number of optical units and the number of filling elements.

[0013] In some embodiments, the lowest point of the texture is located in the region formed by two adjacent extended lines; the extended lines are straight lines formed by the intersection of two adjacent optical units and the center point of the stranded air-blown microcable.

[0014] The range of the texture depth d is:

[0015] The range of the texture width L is: 0.5D1≤L≤D1;

[0016] Wherein, the vertical distance d between the lowest point of the texture and the highest point of the outer sheath is the texture depth, the lateral distance L between the peaks at the left and right ends of the texture is the texture width, h is the thickness of the outer sheath, and D1 is the diameter of the optical unit.

[0017] In some embodiments, the weight and dimensions of the stranded air-blown microcable satisfy the following relationship:

[0018] Wherein, ρ is the overall unit density of the optical cable, and 0.0005 g / mm². 3 <ρ<0.0015g / mm 3 M is the overall unit weight of the optical cable, h is the thickness of the outer sheath, D1 is the diameter of the optical unit, and D0 is the diameter of the reinforcing member.

[0019] In some embodiments, the coefficient of dynamic friction of the stranded air-blown microcable is <0.3.

[0020] In some embodiments, the number of light units is six, and the number of textures is two.

[0021] In some embodiments, the number of light units is six, and the number of textures is six.

[0022] In some embodiments, the stranded air-blown microcable further includes a filler element; the filler element has the same diameter as the optical unit; the optical unit and the filler element are stranded together with a reinforcing member at the center.

[0023] In some embodiments, the number of light units is three, the number of filling elements is three, and the number of textures is two or six.

[0024] In some embodiments, the stranded air-blown microcable has 36-144 fiber cores.

[0025] The beneficial effects of the technical solution provided in this application include:

[0026] This application provides a stranded air-blown microcable, including an outer sheath. Multiple optical units are stranded around a reinforcing member within the outer sheath. The surface of the outer sheath has spirally distributed patterns. These patterns are numerous, their dimensions satisfying the design dimensions calculated by a formula, and are uniformly distributed on the circumference of the stranded air-blown microcable's cross-section. A portion of the patterns is symmetrically arranged with the diameter of the reinforcing member as the axis of symmetry. The straightness factor β of the stranded air-blown microcable is ≤0.02. Due to the reasonable and symmetrical arrangement of the patterns, the airflow generated by the air-blowing process acts uniformly on the outside of the outer sheath, forming optimal thrust to increase the air-blowing distance. Simultaneously, because the straightness factor is less than the design value, these two factors work together to reduce linear changes during the air-blowing process and increase the air-blowing force, ultimately increasing the air-blowing distance on routes with many bends. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 A schematic cross-sectional view of the first type of stranded air-blown microcable in Embodiment 1 provided for the present application;

[0029] Figure 2 A schematic cross-sectional view of the second form of the stranded air-blown microcable in Embodiment 1 provided for the purposes of this application;

[0030] Figure 3 A schematic cross-sectional view of the stranded air-blown microcable in Embodiment 2 provided for the present application;

[0031] Figure 4 A three-dimensional structural diagram of the stranded air-blown microcable provided in the embodiments of this application;

[0032] Figure 5 A diagram illustrating the linearity test method provided in an embodiment of this application.

[0033] In the diagram: 1. Reinforcing component; 2. Optical unit; 3. Outer sheath; 4. Texture. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0035] The terminology explained in this application is as follows:

[0036] The straightness factor (or linearity factor) of an optical cable refers to the ratio of the maximum amplitude between the optical cable and two parallel lines after the optical cable is taken off the reel, straightened at both ends, and released horizontally, to the length of the optical cable.

[0037] The coefficient of dynamic friction of an optical cable is a physical quantity that measures the magnitude of frictional resistance under dynamic friction conditions. It reflects the resistance encountered by the optical cable during its movement. The magnitude of the coefficient of dynamic friction directly affects the ease of operation and durability of the optical cable during laying, retrieval, and routine maintenance.

[0038] The overall unit weight of an optical cable is the weight of one unit length of the optical cable; one unit is one meter, ten meters, etc.; the overall unit density of an optical cable is the ratio of the overall unit weight of the optical cable to the dimensions of each component of the optical cable.

[0039] The reason for this application is that, with the scarcity of urban land and pipeline resources, stranded air-blown microcables are facing a variety of complex routes. Routes with many bends will require better air-blowing performance in order to meet the laying requirements.

[0040] In related technologies, the air-blowing performance of stranded air-blowing microcables is affected by various factors, including the surface texture, coefficient of friction, weight, outer diameter, and straightness of the optical cable. Current industry patents primarily focus on the shape of the surface texture to alter the airflow, without specifying the size of the texture. Extensive experimental data reveals that texture size (depth and size), straightness factor, cable weight, and outer diameter all significantly impact the air-blowing performance. Therefore, comprehensive optimization of surface texture size, coefficient of friction, cable weight, outer diameter, and straightness is necessary to ensure successful cable laying under complex routes.

[0041] Therefore, this application provides a stranded air-blown microcable to solve the problem in related technologies that simply changing the texture shape of the air-blown optical cable is insufficient to meet the air-blowing distance requirements of routes with many bends.

[0042] A layered air-blown microcable includes an outer sheath 3, inside which are provided multiple optical units 2 twisted together with a reinforcing member 1 as the center, and the surface of the outer sheath 3 is provided with spirally distributed textures 4.

[0043] There are multiple textures 4, which are evenly distributed on the circumference of the cross-section of the stranded air-blown microcable; some textures 4 and other textures 4 are symmetrically arranged with the diameter of the reinforcing member 1 as the axis of symmetry.

[0044] The straightness factor β of the stranded air-blown microcable is ≤0.02.

[0045] The above structure, due to the symmetrical and uniform arrangement of the texture 4, ensures that the airflow generated by the air blowing acts evenly on the outside of the outer sheath 3, thereby increasing the air blowing distance. At the same time, since the linearity factor is less than the design value, the three factors work together to reduce friction and linear change during the air blowing process, and increase the air blowing force, ultimately increasing the air blowing distance on routes with many bends.

[0046] The above effects are explained as follows:

[0047] refer to Figure 5 The test method for the straightness factor β of the air-blown micro-cable is as follows: Take a section of optical cable of length L from the cable reel that has been wound up, fix one end of the cable and untwist it. Two people pull the cable straight along a straight line and place it on a horizontal surface. The two people release the cable simultaneously. When the cable comes to rest, measure the maximum amplitude D between the two parallel lines of the cable's wave crest and trough. In the experiment, the optical cable length was 10m ≤ L ≤ 20m. For example, when the optical cable length was 10m, the axial deviation distance should be ≤0.2m. When the optical cable length was 20m, the axial deviation distance should be less than 0.4m.

[0048] The small linearity factor also results in a small amplitude during the air blowing process, which leads to less linear change during the air blowing process and is more conducive to laying in routes with many bends.

[0049] Furthermore, the dynamic friction coefficient of the stranded air-blown microcable is <0.3. The smaller the dynamic friction coefficient, the smaller the resistance. By changing the outer sheath material of the optical cable, the influence of the dynamic friction coefficient of this structure on the air-blowing efficiency can be changed. Therefore, any material that can make the dynamic friction coefficient <0.3 can be used.

[0050] In some preferred embodiments, to comprehensively improve the air blowing effect, the texture size of texture 4, namely its depth and size, is set:

[0051] The first setup method is referenced. Figure 1 and Figure 2

[0052] The lowest point z1 of the ridge 4 is located on the extension line; the extension line x is the straight line formed by the intersection point z2 of two adjacent optical units 2 and the center point z3 of the stranded air-blown microcable;

[0053] The range of texture depth d for texture 4 is:

[0054]

[0055] Texture width 4

[0056] Wherein, the vertical distance d between the lowest point of texture 4 and the highest point of the outer sheath is the texture depth, the lateral distance L between the peaks at the left and right ends of texture 4 is the texture width; h is the thickness of the outer sheath 3, D1 is the diameter of the optical unit 2, D0 is the diameter of the reinforcing member 1; n is the number of optical units 2, or n is the sum of the number of optical units 2 and the number of filling elements.

[0057] This form corresponds to the case where the lowest point of the corresponding pattern 4 is on the extension line. In addition, the stranded air-blown microcable also includes a filler element; the filler element has the same diameter as the optical unit 2; the optical unit 2 and the filler element are stranded together with the reinforcing member 1 as the center; the sum of the number of optical units 2 and the filler element is n.

[0058] For the second setup method, please refer to... Figure 3

[0059] The lowest point of ripple 4 is located in the region formed by two adjacent extended lines; the extended lines are the intersection of two adjacent optical units 2 and the middle of the stranded air-blown microcable.

[0060] The straight line formed by the center point;

[0061] The range of texture depth d for texture 4 is:

[0062] The width L of texture 4 is within the range of: 0.5D1≤L≤D1;

[0063] Among them, the vertical distance d between the lowest point of texture 4 and the highest point of the outer sheath is the texture depth, the lateral distance L between the peaks at the left and right ends of texture 4 is the texture width, h is the thickness of the outer sheath 3, and D1 is the diameter of the optical unit 2.

[0064] Both of the above methods specify the depth and width of the ridge 4, but the air blowing distance is also related to the weight and size of the optical cable, so the following settings are also required:

[0065] refer to Figure 1 The weight and dimensions of the stranded air-blown microcable satisfy the following relationship:

[0066] Where ρ is the overall unit density of the optical cable, and 0.0005 g / mm². 3 <ρ<0.0015g / mm 3 M is the overall unit weight of the optical cable, h is the thickness of the outer sheath 3, D1 is the diameter of the optical unit 2, and D0 is the diameter of the reinforcing member 1.

[0067] To illustrate the specific effects of the above settings, please refer to the following actual experiments, which provide two examples:

[0068] Example 1 (corresponding) Figure 1 and Figure 2 (in the form)

[0069] This embodiment is a stranded optical cable with 96 optical fiber cores. It includes, in sequence, one central reinforcing member, six optical unit sleeves, two binding yarns for the cable cores, an outer sheath, and a sheath surface texture.

[0070] The central reinforcement is 1.7mm thick, the optical unit sleeve is 1.55mm thick, the outer sheath is 0.6mm thick, and the outer diameter of the optical cable is 6.0mm.

[0071] In this embodiment, there are 6 surface textures on the circumference of the optical cable cross-section, which are symmetrical about the center, and the lowest point of each texture is located on the extension line of the intersection of the two sleeves and the center of the optical cable. According to the texture width formula... It can be seen that the fiber optic cable texture L in this embodiment is 3mm.

[0072] The results of air blowing verification of optical cables with different texture depths are shown in Table 1.

[0073] Table 1

[0074]

[0075]

[0076] Table 1 shows that when the fiber optic cable's rib width remains constant, the rib depth satisfies the formula... At that time, the air blowing performance was better.

[0077] Furthermore, in this embodiment, the six stripes are spirally distributed along the axial direction of the optical cable on the surface of the outer sheath.

[0078] Furthermore, the straightness of the optical cable was investigated, and the experimental method was as follows: Figure 3 Take a 10m length of optical cable from the cable reel, secure one end, and untwist the cable. Two people pull the cable straight and place it on a horizontal surface. Release the cable simultaneously. When the cable comes to rest, measure the maximum amplitude D between the two parallel lines of the cable's wave crest and trough. The straightness of optical cables was altered by using different optical cable manufacturing processes. The air blowing experiment data are shown in Table 2.

[0079] Table 2

[0080]

[0081] Table 2 shows that when the straightness factor of the optical cable is ≤0.02, the optical cable has good air blowing performance.

[0082] Furthermore, by changing the outer sheath material of the optical cable, the influence of the dynamic friction coefficient of the optical cable in this structure on the air blowing efficiency was investigated. The experimental method is the circular drum method (2.5π method) in standard YD / T 1460.1, and the experimental data are shown in Table 3.

[0083] Table 3

[0084]

[0085] According to Table 3, when the dynamic friction coefficient of the optical cable is less than 0.3, the optical cable has good air blowing efficiency.

[0086] Since the outer diameter and weight of the optical cable significantly affect its air-blowing performance, and these factors are collectively reflected in the cable density, this embodiment keeps the outer diameter constant. By altering the density of the raw materials used in the optical cable, the overall unit weight of the cable is changed, while other factors remain constant. The effect of the overall unit density of the optical cable on its air-blowing performance is investigated. The formula for the overall unit density of the optical cable is: The results are shown in Table 4.

[0087] Table 4

[0088]

[0089] According to Table 4, when the density of the optical cable is between 0.0005 and 0.0015 g / mm3, the optical cable has good air blowing efficiency.

[0090] From the above, it can be observed that when the lowest point of the optical cable ripple is located on the extension line of the intersection of the two sleeves and the center of the optical cable, the ripple depth satisfies the following condition. The straightness satisfies the straightness factor β≤0.02, the dynamic friction coefficient is less than 0.3, and the density ρ is between 0.0005-0.0015 g / mm3, indicating that the optical cable has good air blowing efficiency.

[0091] Example 2 (corresponding) Figure 3 (in the form)

[0092] This second embodiment is a stranded optical cable with 36 optical fiber cores. It includes, in sequence, one central reinforcing member, three optical unit sleeves, three filler ropes, two binding yarns wrapped around the cable cores, an outer sheath, and a spiral pattern distributed on the surface of the sheath.

[0093] The central reinforcement is 1.9mm thick, the outer diameter of the optical unit sleeve and the filler rope is 1.7mm, the outer sheath thickness is 0.45mm, and the outer diameter of the optical cable is 6.2mm.

[0094] In this embodiment, there are two surface textures on the circumference of the optical cable cross-section. The lowest points of these textures are not on the extension line between the intersection of the two sleeves and the center of the optical cable. The formula will not apply because The value may be greater than the thickness of the sheath.

[0095] Air blowing verification was performed on optical cables with different texture depths, and the results are shown in Table 5.

[0096] Table 5

[0097]

[0098] Table 5 shows that when the lowest point of the texture is not on the extension line of the intersection of the two sleeves and the center of the optical cable, the texture depth satisfies the formula. At that time, the air blowing performance was better.

[0099] Furthermore, this embodiment explored the texture width further, selecting one of the structures with better air blowing performance from Table 1, keeping the texture depth unchanged, and only changing the texture width. The experimental data are shown in Table 6.

[0100] Table 6

[0101]

[0102] According to Table 6, when the lowest point of the optical cable texture is not on the extension line between the intersection of the two sleeves and the center of the optical cable, the width L of the texture on the surface of the optical cable is in the range of 0.5D1-D1, and the air blowing efficiency is better.

[0103] Furthermore, the straightness of the optical cable was investigated, and the experimental method was as follows: Figure 3 The straightness of the optical cable was altered; the air-blowing experiment data are shown in Table 7.

[0104] Table 7

[0105]

[0106] Table 7 shows that when the straightness factor of the optical cable is ≤0.02, the optical cable has good air blowing performance.

[0107] Furthermore, by changing the outer sheath material of the optical cable, the effect of the dynamic friction coefficient of the optical cable with this structure on the air blowing performance was investigated. The experimental method is the circular drum method (2.5π method) in standard YD / T 1460.1, and the experimental data are shown in Table 8.

[0108] Table 8

[0109]

[0110] According to Table 8, when the dynamic friction coefficient of the optical cable is less than 0.3, the optical cable has good air blowing efficiency.

[0111] Since the outer diameter and weight of the optical cable significantly affect its air-blowing performance, and these factors are collectively reflected in the overall unit density of the optical cable, this study investigated the impact of optical cable density on air-blowing performance by varying the unit weight of the optical cable while keeping other factors constant. The formula for the overall unit density of the optical cable is: The results are shown in Table 9.

[0112] Table 9

[0113]

[0114]

[0115] According to Table 9, when the density of the optical cable is between 0.0005 and 0.0015 g / mm3, the optical cable has good air blowing efficiency.

[0116] From the above, it can be observed that when the lowest point of the optical cable ripple is not on the extension line of the intersection of the two sleeves and the center of the optical cable, the ripple depth satisfies the following condition. Texture width meets The straightness satisfies the straightness factor β≤0.02, the dynamic friction coefficient is less than 0.3, and the density ρ is between 0.0005-0.0015 g / mm3, indicating that the optical cable has good air blowing efficiency.

[0117] Based on the above explanation, there are several types of stranded air-blown microcables, for example:

[0118] Form 1: The number of light units 2 is six, and the number of textures 4 is two.

[0119] Form 1: The number of light units 2 is six, and the number of textures 4 is six.

[0120] Form 2: The number of optical units 2 is three, the number of filling elements is three, and the number of patterns 4 is two or six. In the above forms, the number of optical fiber cores in the stranded air-blown microcable is 36-144. Using the above schemes, the air-blown microcable can achieve a blowing distance of over 1500m on curved roads, improving construction efficiency by more than 100%.

[0121] The verification through the above embodiments shows that the number of textures in the stranded air-blown microcable is multiple, and their size meets the design size calculated by the formula, and they are evenly distributed on the circumference of the cross-section of the stranded air-blown microcable. One part of the textures is symmetrically arranged with the diameter of the reinforcing member as the axis of symmetry. The straightness factor β of the stranded air-blown microcable is ≤0.02. Due to the reasonable size and symmetrical and uniform arrangement of the textures, the airflow generated by the air blowing acts evenly on the outside of the outer sheath and forms the best thrust to increase the air blowing distance. At the same time, since the straightness factor is less than the design value, the two factors work together to reduce the linear change in the air blowing process and increase the air blowing force, ultimately increasing the air blowing distance in routes with many bends.

[0122] In the description of this application, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0123] It should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0124] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A layer-stranded air-blowing micro-cable, comprising an outer sheath (3), a plurality of optical units (2) stranded around a strength member (1) inside the outer sheath (3), and a spiral distribution of grooves (4) on the surface of the outer sheath (3), characterized in that: the grooves (4) are multiple and uniformly distributed on the circumference of the cross section of the layer-stranded air-blowing micro-cable; and a part of the grooves (4) are symmetrically arranged with another part of the grooves (4) with the diameter of the strength member (1) as the axis of symmetry.

2. The layer-stranded air-blowing micro-cable according to claim 1, characterized in that: the lowest point of the groove (4) is on an extension line; the extension line is a straight line formed by the intersection of two adjacent optical units (2) and the center point of the layer-stranded air-blowing micro-cable; and the groove depth d of the groove (4) ranges from 0.1 to 0.3 times the diameter of the strength member (1). The straightness factor β of the layer-stranded air-blowing micro-cable is less than or equal to 0.02; the measuring step of the straightness factor β is: cutting a length L of the layer-stranded air-blowing micro-cable to be measured from a rolled cable reel; fixing one end of the layer-stranded air-blowing micro-cable to be measured and performing untwisting treatment; straightening the layer-stranded air-blowing micro-cable to be measured in a straight line direction and placing it horizontally on the ground, and allowing the layer-stranded air-blowing micro-cable to be measured to freely and statically stand in a non-constrained state after being straightened; after the layer-stranded air-blowing micro-cable to be measured is static, measuring the maximum amplitude D in the two parallel line directions between the wave crest and the wave trough in the natural state; and calculating the straightness factor β according to the formula .

3. The layer-stranded air-blowing micro-cable according to claim 1, characterized in that: the lowest point of the groove (4) is in the area formed by two adjacent extension lines; the extension line is a straight line formed by the intersection of two adjacent optical units (2) and the center point of the layer-stranded air-blowing micro-cable.

4. The layer-stranded air-blowing micro-cable according to claim 1, characterized in that: the lowest point of the groove (4) is on the extension line; the extension line is a straight line formed by the intersection of two adjacent optical units (2) and the center point of the layer-stranded air-blowing micro-cable.

5. The layer-stranded air-blowing micro-cable according to claim 1, characterized in that: the dynamic friction coefficient of the layer-stranded air-blowing micro-cable is less than 0.

3. ； The said relief (4) width ;​ Wherein, the vertical distance d between the lowest point of the groove (4) and the highest point of the outer sheath is the groove depth, the lateral distance L between the peaks of the left and right ends of the groove (4) is the groove width; h is the thickness of the outer sheath (3), Diameter of the light unit (2), Diameter of the reinforcing member (1); n is the number of the light unit (2), or n is the sum of the number of the light unit (2) and the number of the filling element.

6. The layer-stranded air-blowing micro-cable according to any one of claims 1-5, characterized in that: the number of optical units (2) is six, and the number of grooves (4) is two.

7. The layer-stranded air-blowing micro-cable according to any one of claims 1-5, characterized in that: the number of optical units (2) is six, and the number of grooves (4) is six. The groove depth d of the grooves (4) ranges from: ; The width of the said grooves (4) The width ranges from: ; Wherein, the vertical distance d of the lowest point of the groove (4) to the highest point of the outer sheath is the groove depth, the lateral distance L of the wave crest of the left and right ends of the groove (4) is the groove width; h is the thickness of the outer sheath (3), is the diameter of the light unit (2).

8. The layer-stranded air-blowing micro-cable according to any one of claims 1-5, characterized in that: the layer-stranded air-blowing micro-cable further comprises a filling element; the diameter of the filling element is the same as that of the optical unit (2); and the optical unit (2) and the filling element are stranded around the strength member (1). The layer-stranded air-blowing micro-cable satisfies the following relationship between the weight and the size: ; wherein said is the overall unit density of the optical cable and is 0.0005 g / mm 3 < p < 0.0015 g / mm 3 ; is the overall unit weight of the optical cable, h is the thickness of the outer jacket (3), is the diameter of the optical unit (2), is the diameter of the strength member (1).

9. The layer-stranded air-blowing micro-cable according to claim 8, characterized in that: the number of optical units (2) is three, and the number of filling elements is three; and the number of grooves (4) is two or six.

10. The layer-stranded air-blowing micro-cable according to any one of claims 1-5, characterized in that: the number of fiber cores of the layer-stranded air-blowing micro-cable is 36-144 cores. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

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