Stranded air-blown micro cable

Abstract

The present application relates to a stranded air-blown micro cable, comprising an outer sheath (3), wherein the outer sheath (3) is internally provided with a plurality of optical units (2) stranded around a strength member (1) as the center; spirally distributed grooves (4) of designed dimensions are provided in a surface of the outer sheath (3); a plurality of grooves (4) are provided, and are evenly distributed on the circumference of the cross-section of the stranded air-blown micro cable; and one portion of the grooves (4) and another portion of the grooves (4) are symmetrically arranged using the diameter of the strength member (1) as the axis of symmetry. The stranded air-blown micro cable has a linearity factor β ≤0.02, and a dynamic friction coefficient less than 0.3. The overall unit density ρ of an optical cable is in the range of 0.0005-0.0015 g / mm3. By means of the above structure, the grooves (4) are symmetrically and uniformly arranged, such that an airflow generated by air blowing uniformly acts on the outside of the outer sheath (3) so as to increase an air blowing distance; moreover, since the linearity factor and the dynamic friction coefficient are less than design values, the combined effect of these two factors reduces linear variations during an air blowing process and improves an air blowing force. In addition, the dimensions of the grooves (4) and the overall unit density of the optical cable are specifically limited, thereby ultimately increasing an air blowing distance in routes having many bends.

Description

Layer-stranded air-blowing micro cable TECHNICAL FIELD

[0001] The present application relates to the technical field of optical cable manufacturing, and in particular to a layer-stranded air-blowing micro cable. BACKGROUND

[0002] With the vigorous development of fiber to the home and metropolitan area networks, the layer-stranded air-blowing micro cable is used more and more widely. With the shortage of urban land and pipeline resources, the layer-stranded air-blowing micro cable is facing various complex routes. For the routes with more bends, better air-blowing performance is required to meet the laying.

[0003] In the related art, the air-blowing performance of the layer-stranded air-blowing micro cable is affected by various factors, which are reflected on the optical cable, including the optical cable surface texture, friction coefficient, and optical cable weight, outer diameter, straightness, etc. that affect the airflow. The current industry-related product patents mainly research the shape of the optical cable surface texture, and change the air-blowing airflow by changing the shape of the texture, but do not limit the size of the texture. Through a large number of test data, it is found that the texture size (depth and size), straightness factor, optical cable weight, outer diameter, etc. all have a great influence on the air-blowing performance of the optical cable, and the air-blowing performance is represented by the air-blowing distance.

[0004] Therefore, how to design an air-blowing optical cable to improve the air-blowing distance to meet the smooth laying of the optical cable is a problem to be solved. SUMMARY

[0005] Embodiments of the present application provide a layer-stranded air-blowing micro cable to solve the problem that in the related art, only changing the texture shape of the air-blowing optical cable cannot meet the requirements of the air-blowing distance for the routes with more bends.

[0006] In a first aspect, a layer-stranded air-blowing micro cable is provided, which includes an outer sheath, a plurality of optical units are arranged in the outer sheath and stranded around a reinforcing member, a spiral distributed texture is arranged on the surface of the outer sheath, the number of the texture is a plurality, and the texture is uniformly distributed on the circumference of the cross section of the layer-stranded air-blowing micro cable; a part of the texture is symmetrically arranged with another part of the texture with the diameter of the reinforcing member as the symmetric axis.

[0007] The straightness factor β of the layer-stranded air-blowing micro cable is less than or equal to 0.02.

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

[0009] The texture depth d of the texture ranges from 0.1 mm to 0.3 mm.

[0010] The texture width of the texture ranges from 0.1 mm to 0.3 mm.

[0011] wherein the vertical distance d between the lowest point of the groove and the highest point of the outer jacket is the groove depth, and the lateral distance L between the peaks at the left and right ends of the groove is the groove width; h is the thickness of the outer jacket, D1 is the diameter of the optical unit, and D0 is the diameter of the reinforcing member.

[0012] In some embodiments, the lowest point of the groove is located in the area formed by the two adjacent extension lines; the extension line is a straight line formed by the intersection of the two adjacent optical units and the center point of the layer-stranded air-blowing micro-cable.

[0013] The groove depth d of the groove is in the range of:

[0014] The groove width L is in the range of: 0.5D1≤L≤D1.

[0015] wherein the vertical distance d between the lowest point of the groove and the highest point of the outer jacket is the groove depth, and the lateral distance L between the peaks at the left and right ends of the groove is the groove width; h is the thickness of the outer jacket, and D1 is the diameter of the optical unit.

[0016] In some embodiments, the layer-stranded air-blowing micro-cable satisfies the following relationship between the weight and the size:

[0017] wherein ρ is the unit density of the optical cable as a whole, and 0.0005g / mm 3 <ρ<0.0015g / mm 3 ; M is the unit weight of the optical cable as a whole, h is the thickness of the outer jacket, D1 is the diameter of the optical unit, and D0 is the diameter of the reinforcing member.

[0018] In some embodiments, the dynamic friction coefficient of the layer-stranded air-blowing micro-cable is <0.3.

[0019] In some embodiments, the number of optical units is six, and the number of grooves is two.

[0020] In some embodiments, the number of optical units is six, and the number of grooves is six.

[0021] In some embodiments, 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; the optical unit and the filling element are stranded around the reinforcing member.

[0022] In some embodiments, the number of optical units is three, and the number of filling elements is three; the number of grooves is two or six.

[0023] In some embodiments, the layer-stranded air-blowing micro-cable has a fiber core number of 36-144 cores.

[0024] The technical scheme provided by the application brings the beneficial effects including:

[0025] The layer-stranded air-blowing micro-cable provided by the embodiment of the application comprises an outer sheath, a plurality of optical units are centrally stranded with the reinforcing member in the outer sheath, and the surface of the outer sheath is provided with spiral distributed lines; the number of the lines is multiple, the size of the lines meets the design size calculated by a formula, and the lines are uniformly distributed on the circumference of the cross section of the layer-stranded air-blowing micro-cable; a part of the lines is symmetrically arranged with another part of the lines as the diameter of the reinforcing member as the symmetric axis; the linearity factor β of the layer-stranded air-blowing micro-cable is less than or equal to 0.02. Due to the reasonable size and symmetric and uniform arrangement of the lines, the air flow generated by air blowing uniformly acts on the outside of the outer sheath and forms the best thrust, so as to increase the air blowing distance. At the same time, due to the fact that the linearity factor is less than the design value, the linear change in the air blowing process is reduced by the joint action of the two factors, and the air blowing force is improved, and finally the air blowing distance in the route with more bending is improved. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical scheme in the embodiment of the application, the drawings needed to be used in the embodiment description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0027] Fig. 1 is a cross-sectional view of a first form of layer-stranded air-blowing micro-cable in embodiment one provided by the embodiment of the application;

[0028] Fig. 2 is a cross-sectional view of a second form of layer-stranded air-blowing micro-cable in embodiment one provided by the embodiment of the application;

[0029] Fig. 3 is a cross-sectional view of a layer-stranded air-blowing micro-cable in embodiment two provided by the embodiment of the application;

[0030] Fig. 4 is a perspective view of a layer-stranded air-blowing micro-cable provided by the embodiment of the application;

[0031] Fig. 5 is a straight linearity test method diagram provided by the embodiment of the application.

[0032] In the drawings: 1, reinforcing member; 2, optical unit; 3, outer sheath; 4, line. DETAILED DESCRIPTION

[0033] To make the purposes, technical solutions, and advantages of the embodiments of the present application clearer, the following will be combined with the accompanying drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work belong to the scope of protection of the present application.

[0034] The terms of the present application are explained as follows:

[0035] The linearity factor of the optical cable refers to the ratio of the maximum amplitude between the optical cable and two parallel lines after the optical cable is pulled straight at both ends and then released horizontally from the reel, and the length of the optical cable.

[0036] The dynamic friction coefficient of the optical cable is a physical quantity for measuring the friction resistance of the optical cable under dynamic friction conditions, which reflects the resistance encountered by the optical cable during movement. The size of the dynamic friction coefficient directly affects the operation convenience and durability of the optical cable during laying, recovery, and daily maintenance.

[0037] The overall unit weight of the optical cable is the weight of the optical cable per unit length; a unit is one meter, ten meters, etc. The overall unit density of the optical cable is the ratio of the overall unit weight of the optical cable to the size of each component of the optical cable.

[0038] The reason for the present application scheme is that with the shortage of urban land and pipeline resources, layer-stranded air-blowing microcables are facing various complex routes. For routes with more bends, better air-blowing performance is required to meet the laying requirements.

[0039] In the related art, the air-blowing performance of the layer-stranded air-blowing microcable is affected by various factors, which are reflected on the optical cable, including the optical cable surface texture, friction coefficient, and optical cable weight, outer diameter, linearity, etc. that affect the airflow. The current industry-related product patents mainly research the shape of the optical cable surface texture, and change the air-blowing airflow by changing the shape of the texture, but do not limit the size of the texture. Through a large number of test data, we found that the texture size (depth, size), linearity factor, optical cable weight, outer diameter, etc. all have a great influence on the air-blowing performance of the optical cable. It is necessary to comprehensively optimize the optical cable surface texture size, friction coefficient, and optical cable weight, outer diameter, linearity, etc. to meet the smooth laying of the optical cable under complex routes.

[0040] Therefore, the embodiments of the present application provide a layer-stranded air-blowing microcable to solve the problem that only changing the texture shape of the air-blowing optical cable in the related art cannot meet the requirements of the air-blowing distance for routes with more bends.

[0041] A layer-stranded air-blowing micro-cable comprises an outer sheath 3, a plurality of optical units 2 being stranded around a reinforcing member 1 in the outer sheath 3, and a spiral groove 4 being arranged on the surface of the outer sheath 3;

[0042] The number of the grooves 4 is multiple and uniformly distributed on the circumference of the cross section of the layer-stranded air-blowing micro-cable; and one part of the grooves 4 is symmetrically arranged with another part of the grooves 4 with the diameter of the reinforcing member 1 as the symmetric axis.

[0043] The linearity factor β of the layer-stranded air-blowing micro-cable is less than or equal to 0.02.

[0044] The above structure is symmetrically and uniformly arranged with the grooves 4, so that the air flow generated by air blowing uniformly acts on the outside of the outer sheath 3 to increase the air blowing distance, and the three factors of the linearity factor less than the design value, the reduction of friction and linearity change in the air blowing process, and the improvement of air blowing force jointly act to ultimately improve the air blowing distance in the route with more bending.

[0045] The above effects are explained as follows:

[0046] Referring to FIG. 5, the test method of the linearity factor β of the air-blowing micro-cable is as follows: a length L of the optical cable is taken from the optical cable reel, one end of the optical cable is fixed, and the optical cable is unwound. Two people straighten the optical cable along a straight line and place it on the horizontal ground, and then simultaneously release the optical cable. When the optical cable is static, the maximum amplitude D between the two parallel lines of the wave crest and the wave trough of the optical cable is tested. The length of the optical cable in the experiment is 10m≤L≤20m. For example, when the length of the optical cable is 10m, the axial deviation distance of the optical cable should be less than or equal to 0.2m. When the length of the optical cable is 20m, the axial deviation distance of the optical cable should be less than or equal to 0.4m.

[0047] The small linearity factor also leads to small amplitude in the air blowing process, so that the linearity change in the air blowing process is small, which is more conducive to the laying in the route with more bending.

[0048] Further, the dynamic friction coefficient of the layer-stranded air-blowing micro-cable is less than 0.3. The smaller the dynamic friction coefficient, the smaller the resistance. The dynamic friction coefficient of the optical cable is changed by changing the material of the outer sheath of the optical cable, so that the material with a dynamic friction coefficient less than 0.3 can be used.

[0049] In some preferred embodiments, in order to comprehensively improve the air blowing effect, the groove size of the groove 4, that is, the depth and size, is set as follows:

[0050] The first setting form is shown in FIGS. 1 and 2.

[0051] The lowest point z1 of the groove 4 is on the extension line; the extension line x is a straight line formed by the intersection z2 of the two adjacent optical units 2 and the center point z3 of the layer-stranded air-blowing micro-cable.

[0052] The range of the groove depth d of the groove 4 is:

[0053] The range of the groove width L of the groove 4 is: 0.5D1≤L≤D1;

[0054] 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 transverse distance L between the peaks at the left and right ends of the groove 4 is the groove width; h is the thickness of the outer sheath 3, D1 is the diameter of the light unit 2, and D0 is the diameter of the reinforcing member 1.

[0055] This form is the case where the lowest point of the groove 4 is on the extension line. In addition, the layer-stranded air blowing microcable also includes a filling element; the filling element has the same diameter as the light unit 2; the light unit 2 and the filling element are stranded around the reinforcing member 1; and the sum of the number of the light unit 2 and the filling element is n.

[0056] The second setting form, referring to FIG. 3

[0057] The lowest point of the groove 4 is located in the area formed by the two adjacent extension lines; the extension line is a straight line formed by the intersection point of the two adjacent light units 2 and the center point of the layer-stranded air blowing microcable;

[0058] The range of the groove depth d of the groove 4 is:

[0059] The range of the groove width L of the groove 4 is: 0.5D1≤L≤D1;

[0060] The range of the groove width L of the groove 4 is: 0.5D1≤L≤D1;

[0061] 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 transverse distance L between the peaks at the left and right ends of the groove 4 is the groove width; h is the thickness of the outer sheath 3, and D1 is the diameter of the light unit 2.

[0062] Both of the above two forms specifically limit the depth and width of the groove 4, but the blowing distance is also related to the weight and size of the optical cable, so there are the following settings:

[0063] Referring to FIG. 1, the weight and size of the layer-stranded air blowing microcable satisfy the relationship:

[0064] Wherein, ρ is the unit density of the whole optical cable, and 0.0005g / mm 3 <ρ<0.0015g / mm 3 ; M is the unit weight of the whole optical cable, h is the thickness of the outer sheath 3, D1 is the diameter of the light unit 2, and D0 is the diameter of the reinforcing member 1.

[0065] To illustrate the specific effect of the above arrangement, reference is made to the actual test carried out below, which provides two embodiments, specifically:

[0066] Embodiment one (corresponding to the form of FIG. 1 and FIG. 2)

[0067] This embodiment one is a layer-stranded optical cable, with 96 fiber cores. It comprises, in sequence, 1 central strength member, 6 optical unit jackets, 2 binding yarns for winding the cable core, an outer sheath, and a sheath surface texture.

[0068] Among them, the central strength member is 1.7 mm, the optical unit jacket is 1.55 mm, the outer sheath thickness is 0.6 mm, and the outer diameter of the optical cable is 6.0 mm.

[0069] In this embodiment, there are 6 surface textures on the cross-sectional circumference of the optical cable, which are symmetrically along the center, and the lowest points of the textures are all on the extension line of the intersection of the two jackets and the center of the optical cable. According to the texture width formula it can be known that the texture L of the optical cable of this embodiment is 3 mm.

[0070] Through air blowing verification of optical cables with different texture depths, the results are shown in Table 1.

[0071] Table 1

[0072] According to Table 1, it can be found that when the texture width of the optical cable is unchanged, the texture depth satisfies the formula , the air blowing performance is better.

[0073] Further, the 6 textures of this embodiment are helically distributed on the surface of the outer sheath along the axial direction of the optical cable.

[0074] Further, the straightness of the optical cable is explored, and the experimental method is shown in FIG. 3: 10 m long optical cable is taken from the collected cable reel, one end of the optical cable is fixed, and the optical cable is unwound. Two people straighten the optical cable along a straight line and place it on the horizontal ground, both hands are released at the same time, and when the optical cable is stationary, the maximum amplitude D between the two parallel lines of the optical cable wave crest and trough is tested, The straightness of the optical cable is changed by different optical cable production processes, and the air blowing experimental data is shown in Table 2.

[0075] Table 2

[0076] According to Table 2, it can be found that when the straightness factor of the optical cable is ≤0.02, the optical cable has better air blowing performance.

[0077] Further, by changing the outer sheath material of the optical cable, the influence of the dynamic friction coefficient of the optical cable on the air blowing efficiency is investigated. The experimental method is referred to the drum method (2.5π method) in the standard YD / T 1460.1, and the experimental data are shown in Table 3.

[0078] Table 3

[0079] 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.

[0080] Since the outer diameter and weight of the optical cable also have a great influence on the air blowing performance, and the outer diameter and weight can be comprehensively reflected in the density of the optical cable. Further, in this embodiment, the outer diameter of the optical cable is kept unchanged, the overall unit weight of the optical cable is changed by changing the density of the raw material of the optical cable, and other factors are unchanged, and the influence of the overall unit density of the optical cable on the air blowing performance is investigated. The overall unit density of the optical cable is The results are shown in Table 4.

[0081] Table 4

[0082] According to Table 4, when the density of the optical cable is between 0.0005-0.0015g / mm3, the optical cable has good air blowing efficiency.

[0083] From the above, it can be found that when the lowest point of the groove of the optical cable is on the extension line between the intersection of the two sleeves and the center of the optical cable, the groove depth satisfies The linearity satisfies the linearity factor β≤0.02, the dynamic friction coefficient is less than 0.3, and the density ρ is between 0.0005-0.0015g / mm3, and the optical cable has good air blowing efficiency.

[0084] Example Two (corresponding to the form of FIG. 3)

[0085] This embodiment two is a layer-stranded optical cable, and the number of optical fiber cores is 36. It sequentially comprises one central reinforcing member, three optical unit sleeves, three filling ropes, two binding yarns wrapped around the cable core, an outer sheath, and grooves spirally distributed on the surface of the sheath.

[0086] Among them, the central reinforcing member is 1.9mm, the outer diameter of the optical unit sleeve and the filling rope is 1.7mm, the thickness of the outer sheath is 0.45mm, and the outer diameter of the optical cable is 6.2mm.

[0087] In this embodiment, there are two surface grooves on the cross-sectional circumference of the optical cable, and the lowest points of the grooves are not on the extension line between the intersection of the two sleeves and the center of the optical cable. At this time, The formula will not be applicable because The value may be greater than the thickness of the sheath.

[0088] Air blowing verification is performed on optical cables with different groove depths, and the results are shown in Table 5.

[0089] Table 5

[0090] According to Table 5, when the lowest point of the groove is not on the extension line of the intersection of the two tubes and the center of the optical cable, the groove depth satisfies the formula , the air blowing performance is better.

[0091] Further, the embodiment further explores the groove width, selects one of the structures with better air blowing performance in Table 1, keeps the groove depth unchanged, and only changes the groove width. The experimental data are shown in Table 6.

[0092] Table 6

[0093] According to Table 6, when the lowest point of the groove of the optical cable is not on the extension line of the intersection of the two tubes and the center of the optical cable, the width L of the groove on the surface of the optical cable is located in the interval of 0.5D1-D1, and the air blowing performance is better.

[0094] Further, the straightness of the optical cable is explored, and the experimental method is referred to Figure 3. The straightness of the optical cable is changed, and the air blowing experimental data are shown in Table 7.

[0095] Table 7

[0096] According to Table 7, when the straightness factor of the optical cable is less than or equal to 0.02, the optical cable has better air blowing performance.

[0097] Further, by changing the material of the outer sheath of the optical cable, the influence of the dynamic friction coefficient of the optical cable on the air blowing performance of the structure of the optical cable is investigated, the experimental method is referred to the round drum method (2.5π method) in the standard YD / T 1460.1, and the experimental data are shown in Table 8.

[0098] Table 8

[0099] According to Table 8, when the dynamic friction coefficient of the optical cable is less than 0.3, the optical cable has better air blowing performance.

[0100] Since the outer diameter and the weight of the optical cable also have a great influence on the air blowing performance, and the outer diameter and the weight can be comprehensively reflected in the overall unit density of the optical cable. In this scheme, by changing the unit weight of the optical cable, other factors are unchanged, the influence of the density of the optical cable on the air blowing performance is investigated, and the overall unit density formula of the optical cable is The results are shown in Table 9.

[0101] Table 9

[0102] According to Table 9, when the density of the optical cable is between 0.0005-0.0015 g / mm3, the optical cable has better air blowing performance.

[0103] From the above, it can be found that when the lowest point of the optical cable pattern is not on the extension line of the intersection of the two tubes and the center of the optical cable, the pattern depth satisfies The pattern width satisfies The linearity satisfies the linearity factor β≤0.02, the dynamic friction coefficient is less than 0.3, the density ρ is between 0.0005-0.0015 g / mm3, and the optical cable has better air blowing performance.

[0104] From the above, there are several forms of layer-stranded air blowing microcables, for example:

[0105] Form one, the number of optical units 2 is six, and the number of patterns 4 is two.

[0106] Form one, the number of optical units 2 is six, and the number of patterns 4 is six.

[0107] Form two, the number of optical units 2 is three, and the number of filling elements is three; the number of patterns 4 is two or six. The number of optical fiber cores of the layer-stranded air blowing microcable in the above form is 36-144 cores. The air blowing distance of the air blowing microcable formed by the above scheme under the bending route can reach more than 1500m, and the construction efficiency is improved by more than 1 times.

[0108] Through the verification of the above embodiments, it is proved that the number of patterns of the layer-stranded air blowing microcable is multiple, the size satisfies the design size calculated by the formula, and is uniformly distributed on the circumference of the cross section of the layer-stranded air blowing microcable; a part of the patterns is symmetrically arranged with another part of the patterns with the diameter of the reinforcing member as the symmetry axis; the linearity factor β of the layer-stranded air blowing microcable is less than or equal to 0.02. Due to the reasonable size of the patterns, the symmetric and uniform arrangement, the air flow generated by the air blowing uniformly acts on the outside of the outer sheath and forms the best thrust to increase the air blowing distance, and at the same time, due to the linearity factor being less than the design value, the linear change in the air blowing process is reduced by the joint action of the two factors, and the air blowing force is improved, and finally the air blowing distance under the route with more bending is improved.

[0109] In the description of the present application, it should be noted that the terms "upper", "lower", and the like are used for indicating the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. Unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connecting" should be interpreted broadly, for example, can be fixed connection, can also be detachable connection, or integrally connected; can be mechanical connection, can also be electrical connection; can be directly connected, can also be indirectly connected through an intermediate medium, can be the internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0110] It should be noted that in the present application, relational terms such as "first" and "second", and the like are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus including a series of elements includes not only those elements, but also other elements not explicitly listed, or other elements inherent in such a process, method, article or apparatus. Without more limitations, the element defined by the statement "comprising a" does not exclude the presence of other identical elements in the process, method, article or apparatus including the element.

[0111] The above is only a specific embodiment of the present application, which enables those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features applied herein.

Claims

1. A layer-stranded air-blown micro-cable, comprising an outer sheath (3), a plurality of optical units (2) stranded around a strength member (1), and a spiral distribution of grooves (4) on the surface of the outer sheath (3), characterized in that: the grooves (4) are multiple and evenly distributed on the circumference of the cross-section of the layer-stranded air-blown micro-cable; a part of the grooves (4) are symmetrically arranged with another part of the grooves (4) as the diameter of the strength member (1) as the axis of symmetry; the linearity factor β of the layer-stranded air-blown micro-cable is less than or equal to 0.

02. 2.The layer-stranded air-blown micro-cable of 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-blown micro-cable; 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 horizontal distance L between the left and right ends of the peak of the groove (4) is the groove 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 strength 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. 3.The layer-stranded air-blown micro-cable of 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-blown micro-cable; the width L of the groove (4) is in the range of 0.5D1≤L≤D1; 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 horizontal distance L between the left and right ends of the peak of the groove (4) is the groove width; h is the thickness of the outer sheath (3), D1 is the diameter of the optical unit (2). 4.The layer-stranded air-blown micro-cable of claim 1, characterized in that: the strength member (1) is a round strength member. 5.The layer-stranded air-blown micro-cable of claim 1, characterized in that: the dynamic friction coefficient of the layer-stranded air-blown micro-cable is less than 0.

3. The groove depth d of the grooves (4) ranges from: said relief (4) width 6.The layer-stranded air-blown micro-cable of 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-blown micro-cable of 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. 8.The layer-stranded air-blown micro-cable of any one of claims 1-5, characterized in that: the layer-stranded air-blown micro-cable further comprises a filling element; the filling element has the same diameter as the optical unit (2) ; the optical unit (2) and the filling element are stranded around the strength member (1). The groove depth d of the grooves (4) ranges from: 9.The layer-stranded air-blown micro-cable of claim 8, characterized in that: the number of optical units (2) is three, and the number of filling elements is three; the number of grooves (4) is two or six. 10.The layer-stranded air-blown micro-cable of any one of claims 1-5, characterized in that: the number of fiber cores of the layer-stranded air-blown micro-cable is 36-144 cores. ​ The layer-stranded air-laid microcable satisfies the relationship between the weight and the size of the cable: wherein p is the overall unit density of the optical cable, and 0.0005 g / mm 3 < p < 0.0015 g / mm 3 ; M is the overall unit weight of the optical cable, h is the thickness of the outer jacket (3), Di is the diameter of the optical unit (2), and Do is the diameter of the strength member (1). ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

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