Air blown optical cable and construction method suitable for high temperature installation work environment

Abstract

The application discloses a kind of air blowing optical cable suitable for high temperature installation operation environment, including: sheath and cable core received in sheath;The sheath adopts sheath material, and the vicat softening point of high molecular thermoplastic material is between 60 DEG C~90 DEG C.This application solves the problem of sharp shortening of air blowing distance caused by temperature change of outside working environment of air blowing microcable by optimizing thermodynamic performance of sheath material, without special consideration of the influence of construction working environment temperature, widens construction window period, makes the popularization and application of air blowing laying technique more easily accepted;Solve the limitation of air blowing microcable application area, whether in summer or winter can be constructed, whether in the cold region of northern hemisphere is used, or in the tropic region of southern hemisphere is used, as long as in the same specification pipeline air blowing, same air blowing microcable product can be used, without multiple product development.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of optical communication, and more particularly relates to an air-blow optical cable suitable for high-temperature installation operation environment and a construction method. BACKGROUND

[0002] The technical principle of air-blow micro-pipe micro-cable for air-blow laying of communication is that air is compressed by an air compressor and injected into a communication pipe to form high-pressure and high-speed airflow in the communication pipe, and the airflow drives the micro-cable to move quickly in the micro-pipe to achieve the purpose of quick laying of the optical cable. For a long time, improving the laying distance of the air-blow micro-cable has been a major concern in the field

[0003] Long-term experimental exploration shows that the laying distance of the air-blow micro-cable is significantly shortened when the construction is carried out in summer. Some technical personnel believe that many factors cause the laying distance of the optical cable to be shortened in the high-temperature installation operation environment, such as the technical personnel of XXX Company believe that: on the one hand, due to the high temperature in summer, the air density decreases, resulting in a decrease in airflow velocity; on the other hand, the high-temperature and high-humidity gas components increase in the pipeline of the air-blow cable machine, the airflow viscosity increases, resulting in an increase in the tangential fluid power “shear force” gathered along the length of the optical cable; at the same time, the micro-softening of the silicon layer on the inner wall of the silicon core pipe used for laying the optical cable and the increase in the friction coefficient of the inner wall are also one of the reasons for the shortening of the laying distance.

[0004] Willem Griffioen, Jouni Heinonen and others of Plumettaz.com Company expounded the research report on the relationship between the working environment temperature and the air-blow installation distance at the 2011 IWCS International Cable Conference Forum. The report pointed out that the friction coefficient between the air-blow micro-cable and the inner wall of the air-blow pipe changes with temperature in different installation operation working environment temperatures. For example, in summer, when the actual installation operation working environment temperature is about 10℃-30℃, the change of the friction coefficient between the air-blow optical cable and the laying pipe is a slow upward trend with the increase of temperature, and when the working environment temperature exceeds 30℃, the change of the friction coefficient between the air-blow optical cable and the laying pipe begins to show a sharp upward trend with the increase of temperature. Therefore, some treatment schemes for improving the air-blow distance of the optical cable are proposed in the report, such as: using a micro-pipe with a groove, adding an air cooler during air-blowing to reduce the temperature of compressed air; adding an appropriate amount of lubricant by a special machine to reduce the friction coefficient between the optical cable and the pipe wall; and adding a water vapor removal device to reduce the influence of air humidity.

[0005] However, in the installation process of air-blowing of optical cable, the friction force acting on the optical cable is very complex: on the one hand, the clamping friction force between the air-blowing machine belt wheel and the optical cable provides the driving power for the air-blowing installation of the optical cable; on the other hand, the friction force between the pipe wall and the optical cable hinders the air-blowing installation of the optical cable. The most complex is the friction force between the compressed air and the surface of the optical cable, which is jointly influenced by the bending shape of the optical cable during air-blowing, the structure and topography of the installation pipeline, and the temperature of the gas composition: sometimes, especially when the installation pipeline is a straight pipeline, the friction force between the compressed air and the optical cable serves as one of the driving forces to drive the optical cable to move in the pipeline, on the other hand, the tangential fluid power "shear force" gathered along the length of the optical cable is one of the factors hindering the forward movement of the optical cable, especially when the pipeline is bent, the turbulence of the airflow (commonly known as air resistance in the industry) will also more obviously hinder the forward movement of the optical cable.

[0006] With the change of the working environment temperature during installation operation, the surface properties of the air-blowing micro-pipeline and micro-cable have extremely complex effects on the installation distance of the air-blowing optical cable at high temperature. Therefore, these treatment schemes proposed in the document have obvious advantages for improving the air-blowing distance, but the disadvantage is that the equipment investment cost is increased, such as the need to increase many professional auxiliary equipment; and a special low-friction coefficient lubricant is also needed, and the selection of the amount of lubricant in different temperature environments and pipeline specifications has different requirements, which not only increases the construction cost, but also importantly increases the technical operation difficulty, which needs special training operation, and objectively plays a certain limiting role for the development and popularization of technology. SUMMARY

[0007] In view of the above defects or improvement needs of the prior art, the present application provides an air-blowing micro-cable suitable for wider installation operation environment and a construction method thereof, which aims to maintain the surface properties of the air-blowing micro-cable at a good rate when the natural working environment temperature changes between 0℃ and 45℃, without the need to increase a special air cooler and add a low-friction coefficient lubricant, thereby solving the technical problem of air-blowing construction installation distance.

[0008] To achieve the above-mentioned purpose, according to one aspect of the present application, an air-blowing optical cable suitable for high-temperature installation operation environment is provided, comprising:

[0009] a sheath,

[0010] and a cable core accommodated in the sheath;

[0011] The sheath material used by the sheath is a high-molecular thermoplastic material with a Vicat softening point of 60℃ to 90℃.

[0012] Preferably, the air-blown optical cable suitable for high-temperature installation working environment, the penetration of the sheath material is less than 1.25mm, preferably between 0.95mm and 1.25mm, within the range of 10℃ to 70℃.

[0013] Preferably, the air-blown optical cable suitable for high-temperature installation working environment, the penetration of the sheath material increases no more than 0.1mm with the increase of temperature, per 10° increase of temperature.

[0014] Preferably, the air-blown optical cable suitable for high-temperature installation working environment, the penetration of the sheath material at 25℃ is no more than 1.0mm, and in particular, the penetration at 40℃ to 60℃ is no more than 1.15mm.

[0015] Preferably, the air-blown optical cable suitable for high-temperature installation working environment, the penetration of the sheath material at 40℃ is no more than 1.1mm; at 50℃ is no more than 1.13mm; at 60℃ is no more than 1.14mm.

[0016] Preferably, the air-blown optical cable suitable for high-temperature installation working environment, the outer diameter of the cable is between 1.1mm and 4.2mm, and the thickness of the sheath is between 0.2mm and 0.8mm.

[0017] Preferably, the air-blown optical cable suitable for high-temperature installation working environment, the air-blown optical cable has a compression deformation degree of less than 5% within the range of 10℃ to 70℃.

[0018] Preferably, the air-blown optical cable suitable for high-temperature installation working environment, the cable body has a groove with a depth of more than 0.05mm, and the length of the sheath on the circumference of the maximum outer diameter of the cross-section of the sheath is less than 50% of the circumference.

[0019] Preferably, the air-blown optical cable suitable for high-temperature installation working environment, the groove is a straight groove.

[0020] According to another aspect of the present application, a construction method of the air-blown optical cable is provided, which comprises the following steps:

[0021] The air-blown optical cable is laid by air blowing method; a clamping force is applied to the input end of the cable so that the compression deformation degree is less than 5%;

[0022] A pushing force is applied to the input end;

[0023] Compressed air is supplied to the input end;

[0024] The air blowing working environment temperature is between 0℃ and 45℃.

[0025] Preferably, the air blowing optical cable construction method has a clamping force generally between 1-5N, a pushing force upper limit less than or equal to 40N, and an upper limit of compressed air pressure of 15 BAR.

[0026] Overall, compared with the prior art, the above technical solutions conceived by the present application can achieve the following beneficial effects due to the use of a new air blowing microcable polyethylene sheath material:

[0027] 1) The present application solves the problem of rapid shortening of air blowing distance caused by changes in external working environment temperature by optimizing the thermodynamic properties of the sheath material, without needing to specially consider the influence of construction working environment temperature, widening the construction window period, making the popularization and application of air blowing laying technology more easily accepted; solving the limitations of air blowing microcable application areas, whether in summer or winter, whether in cold regions of the northern hemisphere or in tropical regions of the southern hemisphere, as long as air blowing is performed in the same specification pipeline, the same air blowing microcable product can be used, without the need for multiple product development.

[0028] More importantly, the present application discloses the correlation between the thermodynamic properties of the sheath material, frictional resistance, and air blowing power, ultimately optimizing the air blowing laying distance of the optical cable.

[0029] 2) The air blowing optical cable construction method provided by the present application does not need to include auxiliary reagents and equipment such as lubricants and coolants, greatly reducing the equipment investment cost of engineering companies, with high economic benefits. At the same time, it reduces the air blowing construction operation difficulty, objectively reduces the construction team access threshold, is more easily accepted by construction personnel, and can effectively promote the popularization and application of air blowing laying technology. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 is the standard needle used in the needle penetration test method of the present application;

[0031] Figure 2 is a schematic diagram of the cross-sectional structure of the no-groove air blowing cable provided by embodiment 1 of the present application;

[0032] Figure 3 is a schematic diagram of the cross-sectional structure of the air blowing pipeline;

[0033] Figure 4 is a schematic diagram of the principle of optical cable air blowing laying;

[0034] Figure 5 is a needle penetration test result diagram of the sheath material of the present application;

[0035] Figure 6 is a friction coefficient test result diagram of the no-groove air blowing cable provided by embodiment 1 of the present application;

[0036] Figure 7is a pressure deformation degree test result graph of the air blowing cable without a groove provided by the embodiment 1 of the present application;

[0037] Figure 8 is an air blowing distance test result graph of the air blowing cable without a groove provided by the embodiment 1 of the present application;

[0038] Figure 9 is a cross-sectional structure schematic diagram of the air blowing cable with a groove provided by the embodiment 2 of the present application;

[0039] Figure 10 is a friction coefficient test result graph of the air blowing cable with a groove provided by the embodiment 2 of the present application;

[0040] Figure 11 is a pressure deformation degree test result graph of the air blowing cable without a groove provided by the embodiment 2 of the present application;

[0041] Figure 12 is an air blowing distance test result graph of the air blowing cable without a groove provided by the embodiment 1 of the present application;

[0042] In all the drawings, the same reference signs are used to represent the same elements or structures, in which: 1 is a pressure seat, 2 is a standard needle, 3 is an optical fiber, 4 is a loose tube, 5 is a cable opening rope, 6 is a sheath, 7 is an air blowing machine master and driven wheel, 8 is an air blowing cable, 9 is an air flow, and 10 is a pipeline. DETAILED DESCRIPTION

[0043] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application is further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and should not be used to limit the present application. In addition, the technical features involved in each embodiment of the present application described below can be combined with each other as long as they do not conflict with each other.

[0044] The present application provides an air blowing optical cable suitable for high temperature installation operation environment, a sheath, and a cable core accommodated in the sheath;

[0045] The sheath material adopted by the sheath is a high molecular thermoplastic material with a Vicat softening point of 60-90℃, typically a high density polyethylene material, the Vicat softening point of which can be adjusted according to the polymerization degree distribution, the higher the polymerization degree of the high molecular, the higher the proportion and the higher the Vicat softening point. And the sheath material has a penetration degree of less than 1.25mm, preferably between 0.95 and 1.25mm, within the range of 10-70℃; at the same time, the penetration degree of the sheath material increases by no more than 0.1mm with the increase of temperature for every 10° increase of temperature; the penetration degree at 25℃ is not more than 1.0mm; in particular, the penetration degree at 40-60℃ is not more than 1.15mm, preferably:

[0046] The penetration at 40℃ is not more than 1.1 mm; the penetration at 50℃ is not more than 1.13 mm; the penetration at 60℃ is not more than 1.14 mm.

[0047] The penetration test method is as follows: a 3 mm thick tablet sheet is placed in a temperature cycle box and kept at the test temperature point for 4 hours, a standard needle tip is applied to the surface of the sheet under a 50 N tension for 5 seconds, and the depth (mm) of penetration into the sheet is measured. The standard needle is as shown in the specification reference material hardness test method, see "People's Republic of China National Standard GB-T 2411-2008 Plastics and Hard Rubber Determination of Indentation Hardness (Shore Hardness) Using a Durometer". Figure 1

[0048] The outer diameter of the cable is 1.1 mm to 4.2 mm, and the thickness of the sheath is 0.2 mm to 0.8 mm, so that the pressure deformation degree of the air blowing optical cable is less than 5% at 10℃ to 70℃. The penetration of the sheath material of the optical cable, the thickness of the sheath, and the outer diameter of the cable simultaneously affect the ability of the optical cable to maintain its shape under lateral pressure during air blowing installation, i.e. the pressure deformation degree , which is represented by the degree of deformation of the air blowing microcable under certain pressure. The specific calculation method of the pressure deformation degree is as follows:

[0049]

[0050] wherein, is the long axis length of the cross section of the air blowing microcable after pressure deformation, is the short axis length of the cross section of the air blowing microcable after pressure deformation.

[0051] Specifically, the pressure deformation degree is determined by the following method:

[0052] A pressure wheel with a bending radius R=50 mm and a width of 10 mm is used as the pressure applying device; the air blowing microcable to be tested is placed in the middle of the pressure wheel under the working environmental temperature, a tension of 5 N is applied for more than 5 seconds, the cable diameter in the direction of force is detected as the short axis length of the cross section of the air blowing microcable after pressure deformation , and the cable diameter in the direction perpendicular to the force is detected as the long axis length of the cross section of the air blowing microcable after pressure deformation ; the pressure deformation degree of the air blowing microcable is calculated.

[0053] ​The improvement of the thermodynamic performance of the sheath material makes it suitable for a wider range of working environment temperature ranges, achieving a wide temperature range of 10-45°C, and when laying at a temperature above 40°C, the laying distance level can still be achieved as when laying at a temperature of 10-25°C. Especially, further maintaining the air-blowing micro-pressure deformation degree at a lower level can further improve the air-blowing laying distance of the optical cable.

[0054] Microscopically, when the outer sheath is subjected to airflow impact, the surface shape changes, affecting the friction between the outer sheath and the airflow and between the outer sheath and the pipeline. The friction is determined by the actual contact area between the objects that are in friction, and the greater the actual contact area, the greater the friction. The actual contact area is related to the size of the normal pressure, the properties of the material, and the roughness of the surface, and is unrelated to the apparent contact area. Generally, the actual contact area is much smaller than the apparent contact area, so macroscopically, it is believed that the friction between rigidly contacted objects is only related to the size of the normal pressure and the roughness of the surface, and is unrelated to the contact area.

[0055] The air-blowing micro-cable that works at high temperatures, if the surface of the cable body forms grooves, the shape affects the friction and the power of the airflow acting on the cable body.

[0056] The relationship between the grooves on the surface of the cable body and the friction is relatively complex and is affected by the sheath material: on the one hand, the groove design increases the surface roughness, and on the other hand, it reduces the apparent contact area. However, since the sheath material is a high polymer material, the surface properties soften under the action of airflow and high temperature, so when air-blowing, the groove reduces the apparent contact area and also significantly reduces the actual contact area. At the same time, it increases the contact area with the airflow, making the cable more easily suspended and improving the driving force of the cable, thus being beneficial to reducing the friction.

[0057] The air-blowing micro-cable provided by the present application uses a sheath material that, at an air-blowing laying working environment temperature of 10-45°C, can cooperate with the groove design of the cable body to reduce the frictional resistance between the sleeve and the air-blowing micro-cable. Specifically, a groove depth of 0.05 mm or more has a significant effect on reducing the frictional resistance. On the circumference of the maximum outer diameter of the sheath cross section, the length of the sheath is less than 50% of the circumference, and the remaining part is the circumference reduced due to the presence of the groove.

[0058] Meanwhile, the groove structure on the surface of the cable body and the softening performance of the sheath material together cause the airflow force to change, on the one hand, increasing the contact area of the sheath material with the airflow existing in the microscopic deformation, thereby improving the airflow acting on the cable, on the other hand, intensifying the lateral force of the airflow on the air-blowing micro cable, which may increase the twisting amplitude of the optical cable, but the straight groove design makes the airflow more likely to make the cable in a suspended state. The above factors jointly affect the laying distance of the air-blowing micro cable, and the straight groove cooperates with the above sheath material to achieve a longer air-blowing laying distance.

[0059] Interestingly, the air-blowing optical cable with a higher sheath Vicat softening point and smaller pressure deformation cooperates with the groove design to further improve the laying distance. If the air-blowing optical cable with a lower sheath Vicat softening point and larger pressure deformation adopts the groove design, it may further increase the frictional resistance, resulting in a decrease in the laying distance instead of an increase, especially at a higher working environment temperature, because the sheath material is too soft, the groove cannot reduce the actual contact area, but instead sharply increases the cable surface roughness, forming the bonding force between the cable surface molecules and the pipe wall, and significantly improving the frictional resistance.

[0060] In a preferred embodiment, the air-blowing optical cable with a specification of an outer diameter of 1.1 mm to 4.2 mm can achieve good laying effect when constructed in summer, i.e., the working environment temperature is above 35℃, usually in the range of 35℃ to 55℃, and the laying distance decreases by no more than 25% relative to the laying and installation at 25℃.

[0061] The construction method of the air-blowing optical cable provided by the present application comprises the following steps: laying the air-blowing optical cable by using the air-blowing method; and applying a clamping force to the input end of the cable so that the pressure deformation degree is less than 5%, and the clamping force is generally between 1 N and 5 N for the center tube type air-blowing micro cable. When generally working at high temperature, too large clamping force may damage the surface properties of the sheath, the air-blowing optical cable is severely deformed, and the skin may be wrinkled or even broken during the pushing process of the air-blowing optical cable. Too small clamping force may cause the air-blowing machine to slip and wear the sheath surface.

[0062] A pushing force is applied to the input end of the cable to make the air-blowing optical cable advance, and the upper limit of the pushing force is less than or equal to 40 N. The main function of the pushing force is to overcome the resistance, and theoretically, the greater the pushing force, the better. In general, 20 N or less is selected for operation in actual engineering applications. The upper limit of the pushing force is set so that when the optical cable cannot be blown in the pipeline, the maximum pushing force does not break the optical cable at the driving wheel and the pipeline inlet. The air-blowing optical cable provided by the present application can still maintain good penetration performance under the condition of temperature rise caused by air-blowing operation, has better cable body stiffness at high temperature, and can withstand a higher upper limit of the pushing force, thereby increasing the laying distance to a certain extent, especially at high temperature.

[0063] The input end thereof is connected to compressed air, and the upper limit of the pressure of the compressed air is 16 BAR. The pressure of the compressed air is relatively large, which provides greater air-blowing power for the advancement of the optical cable and can increase the air-blowing laying distance within a certain range. However, when the pressure of the compressed air is too large, the compressed air does work, which can further sharply increase the temperature of the optical cable in the pipeline relative to the temperature of the external working environment, and the frictional resistance is increased. Therefore, the laying distance cannot be further increased by increasing the pressure of the compressed air, and the pressure of the compressed air at this time is the upper limit of the pressure of the compressed air.

[0064] The air-blowing working environment temperature is 0℃ to 45℃, that is, the upper limit of the air-blowing working environment temperature is 45℃. Within the working environment temperature range, no cooling or heat dissipation process or equipment is required, and no additional lubricant is required.

[0065] The following is an example:

[0066] A cross-sectional view of a central tube type air-blowing microcable commonly used in optical network engineering for a fiber-to-the-home is shown. The number of cores is generally small, and the structures of the examples and comparative examples described below are completely consistent, except that the outer sheath materials are different.

[0067] Example 1

[0068] The present application provides a central tube type air-blowing microcable without a groove: relates to an air-blowing microcable suitable for a wider temperature installation environment operation, such as Figure 2 as shown:

[0069] The diameter of the optical cable is 2.4 mm, which is composed of a polyethylene sheath 6, a loose sleeve 4 inside the sheath, and a cable opening rope 5 between the sheath and the loose sleeve, and the sleeve contains an optical fiber 3. The air-blowing is carried out in a pipeline with a specification of 5 / 3.5 mm as shown in Figure 3 , and the air-blowing principle is shown in Figure 4 .

[0070] The sheath parameters used in the examples and comparative examples are shown in Table 1:

[0071] Table 1 Sheath parameters

[0072]

[0073] The polyethylene of the sheath material c has a molecular weight distribution of 2000 to 6000.

[0074] The polyethylene of the sheath material d has a molecular weight distribution of 4000 to 20000.

[0075] The sheath material c and the sheath material d have a relatively high Vicat softening point and a relatively small compression deformation, and the specific tests are as follows.

[0076] Comparison of the Vicat softening point of the outer sheath material of the optical cable of the comparative example and the optical cable of the example:

[0077] The VST values of the cable jacket materials of the comparative cable and the example cable were tested according to the standard GB / T 1633-2000 B50 test method for Vicat softening temperature of thermoplastics. The VST values of the comparative cable and the example cable are shown in Table 1. The test results show that the cable jacket of the example cable has a higher VST value than the comparative cable.

[0078] Needle penetration test of the outer jacket materials of the comparative cable and the example cable:

[0079] A 3mm thick tablet sheet was placed in a temperature cycle box and kept at the test temperature point for 4 hours. A standard needle was applied to the surface of the sheet with a tension of 50N for 5 seconds, and the depth of penetration into the sheet (mm) was measured. The standard needle, as shown in Figure 5 , is the needle tip in the hardness test method for reference materials, see the national standard GB-T 2411-2008 of the People's Republic of China, "Determination of indentation hardness (Shore hardness) of plastics and ebonite using a durometer". Figure 5 The test results are shown in

[0080] Friction resistance test:

[0081] The comparative cable and the example cable were compared in the same pipe under different working environmental temperatures. The comparative example and the example of the structure center pipe type air blowing micro cable were put into a temperature cycle box with the same standard air micro pipe 5 / 3.5mm. By adjusting the working environmental temperature of the temperature cycle box, the relative friction coefficient of the micro cable and the micro pipe under different temperature conditions was measured. The actual test results are shown in the comparison of friction coefficients at different temperature points (without grooves), as shown in Figure 6 .

[0082] From the results shown in Figure 5 , the example cable has a lower friction coefficient than the comparative cable in a wider temperature environment. When the working environmental temperature is lower than 20℃, the comparative cable and the example cable have no obvious difference in friction coefficient. When the working environmental temperature reaches or exceeds the Vicat softening point temperature of the jacket material, the friction coefficient begins to rise obviously.

[0083] Compression deformation degree test of the comparative cable and the example cable with temperature change:

[0084] The pressure deformation degree of the optical cable directly reflects the surface property retention ability of the blown optical cable. Two main aspects affect the surface property: one is the influence of the blowing clamping force on the surface property. We know that during the blowing process, the blowing machine driving wheel generally pushes the optical cable into the micro tube with a clamping force of not more than 5N, so that the optical cable moves forward in the micro tube; the other is the pressure received by the blown micro cable when turning in the pipeline and the force acting on the wall under the action of gravity. In order to compare the sheath softness of the optical cable, a pair of pressure wheels with a bending radius R = 50mm and a width of 10mm are selected. The optical cable is placed in the middle of the pressure wheel, a tension of 5N is applied, and the deformation amount of the optical cable at different temperature points within 5 seconds is observed. The actual results are shown in Figure 7 .

[0085] As shown in Figure 7 , the high Vicat softening point material has a certain surface property retention ability; after exceeding the Vicat softening point of the material, the surface property of the stressed surface of the optical cable changes under the action of the clamping force.

[0086] Actual blowing distance comparison:

[0087] The blown micro cables of the comparative example and the examples are compared in the actual blown pipeline of the imported Emtelle company 5 / 3.5mm blown pipeline specification. The blown pipeline length is 1200m, the Polymet Kaisha mini-jet blowing machine is used, the pipeline is laid according to the standard IEC blowing site, and the actual blowing distance is shown in Figure 8 .

[0088] As can be seen from the figure, when blowing in a normal temperature environment, the difference in blowing laying distance is not obvious, and it basically meets the actual engineering use requirement. When the working environment temperature changes, especially when the working environment temperature rises to more than 30℃, the blowing distance of the optical cable of the comparative example changes greatly, while the blowing distance of the optical cable of the example changes not drastically, which shows that the high-temperature environment blowing performance has obvious advantages.

[0089] Experiments show that the blown micro cable provided by the example can adapt to a wider working environment temperature under the same structure; when the working environment temperature increases, it has a relatively smooth surface friction coefficient change rate; under the working environment temperature in summer (about 40℃), without using cooling and lubricating means, the blowing laying distance is increased by more than 50%.

[0090] Example 2

[0091] The blown micro cable provided by the example has a groove in the center tube, and relates to a blown micro cable suitable for a wider temperature installation environment operation, as shown in Figure 9The cable diameter is 2.4mm, and the cable is composed of a polyethylene sheath 6, a loose tube 4 in the sheath, and a cable opening rope 5 between the sheath and the loose tube, and the loose tube contains an optical fiber 1. The 5 / 3.5mm specification is used as Figure 3 The gas blowing is carried out in the pipe shown in Figure 4 .

[0092] The polyethylene sheath thickness and material are the same as in Example 1, and the sheath parameters used in the examples and comparative examples are shown in Table 2:

[0093] Table 2 Sheath parameters

[0094]

[0095] The Vicat softening point and penetration performance of the outer sheath material of the comparative cable and the example cable are the same as in Example 1.

[0096] Friction resistance test:

[0097] The comparative cable and the example cable are placed in the same pipe, and the friction coefficients are compared under different working environment temperatures. The comparative example and the example of the central tube type gas blowing microcable are placed in the temperature cycle box with the same standard gas microtube 5 / 3.5mm, and the working environment temperature of the temperature cycle box is adjusted to measure the relative friction coefficient of the microcable and the microtube under different temperature conditions. The actual test results are shown in the table "Comparison of friction coefficients at different temperature points (with grooves)", see Figure 10 .

[0098] From the results of the icon display, the example cable has a lower friction coefficient than the comparative cable in a wider temperature environment. When the working environment temperature is lower than 20℃, the comparative cable and the example cable have no obvious difference in friction coefficient. When the working environment temperature reaches or exceeds the Vicat softening point temperature of the sheath material, the friction coefficient begins to rise sharply.

[0099] Test of the effect of temperature change on the compression deformation of the comparative cable and the example cable:

[0100] The pressure deformation degree of the optical cable directly reflects the surface property retention ability of the air blowing optical cable. Two main aspects affect the surface property: one is the influence of the air blowing clamping force on the surface property. We know that during the air blowing process, the air blowing machine driving wheel generally pushes the optical cable into the micro tube with a clamping force of not more than 5N, so that the optical cable moves forward in the micro tube; the other is the pressure received by the air blowing micro cable when turning in the pipeline and the force acting on the wall under the action of gravity. In order to compare the softness of the optical cable, a pair of pressure wheels with a bending radius R = 50mm and a width of 10mm are selected. The optical cable is placed in the middle of the pressure wheel, a tension of 5N is applied, and the deformation amount of the optical cable at different temperature points within 5 seconds is observed. The actual results are shown in Figure 11 .

[0101] As shown in Figure 11 , the high Vicat softening point material has obvious surface property retention ability; after exceeding the Vicat softening point of the material, the surface property of the stressed surface of the optical cable changes greatly under the action of the clamping force.

[0102] Actual air blowing distance comparison:

[0103] The air blowing micro cables of the comparative example and the embodiments are compared in the actual air blowing in the imported Emtelle 5 / 3.5mm air blowing pipeline specification. The air blowing pipeline length is 1200m, the Polymet Kaisha mini-jet air blowing machine is used, the pipeline is laid according to the standard IEC air blowing site, and the actual air blowing distance is shown in Figure 12 .

[0104] As can be seen from the figure, the air blowing laying distance difference is not obvious when air blowing is carried out in a normal temperature environment, and it basically meets the actual use requirement. When the air blowing working environment temperature changes, especially when the working environment temperature rises to more than 30℃, the air blowing distance of the optical cable of the comparative example changes greatly, while the air blowing distance of the optical cable of the embodiment changes not drastically, which shows that the high temperature environment air blowing performance has obvious advantages.

[0105] Experiments show that the air blowing micro cable provided by the embodiment can adapt to a wider working environment temperature under the same structure; when the working environment temperature increases, it has a relatively smooth surface friction coefficient change rate; under the working environment temperature in summer (about 40℃), without using cooling and lubricating means, the air blowing laying distance is increased by nearly 2 times.

[0106] Through the comparison of Example 1 and Example 2, it is shown that the grooves arranged on the surface of the sheath are beneficial to reduce the friction resistance and improve the air blowing distance.

[0107] Example 3

[0108] The air blowing installation operation was performed on the examples (C, D, or c, d) as follows:

[0109] The cable input / output end applied a clamping force and a pushing force, and compressed air was introduced to perform air blowing installation at 41°C. The test results of the laying distance are shown in Table 3:

[0110] Table 3 Test results of laying distance

[0111]

[0112] It is to be understood that the above-described embodiments are merely illustrative of the principles of the application and that numerous modifications, equivalents and improvements can be effected by those skilled in the art without departing from the scope of the application.

Claims

1. A blown optical cable suitable for use in high temperature installation environments, characterized in that, It comprises: a sheath, and a cable core accommodated in the sheath; The sheath material is a high molecular thermoplastic material with a Vicat softening point between 60℃ and 90℃; The sheath material has a penetration depth of less than 1.25mm at 10℃ to 70℃; The test method of the above penetration depth is as follows: place a 3mm thick tablet sheet in a temperature cycle box, keep it at the test temperature point for 4 hours, apply a standard needle tip with a tension of 50N to the surface of the sheet for 5 seconds, and measure the depth of penetration into the sheet; the standard needle tip is the needle tip in the material hardness test method in the "People's Republic of China National Standard GB-T 2411-2008 Plastics and Hard Rubber Determination of Indentation Hardness (Shore Hardness)".

2. The blown optical cable suitable for use in high temperature installation environments of claim 1, wherein, The sheath material has a penetration depth of 0.95 to 1.25mm at 10℃ to 70℃.

3. The blown optical cable suitable for use in high temperature installation environments of claim 1, wherein, The penetration depth of the sheath material increases by no more than 0.1mm with the increase of temperature every 10°.

4. The blown optical cable suitable for high temperature installation work environment according to any one of claims 1 to 3, wherein The penetration depth of the sheath material at 25℃ is not more than 1.0mm.

5. The blown optical cable suitable for use in high temperature installation environments of claim 4, wherein, The penetration depth of the sheath material at 40℃ to 60℃ is not more than 1.15mm.

6. The blown optical cable suitable for use in high temperature installation environments of claim 4, wherein, The penetration depth of the sheath material at 40℃ is not more than 1.1mm; the penetration depth of the sheath material at 50℃ is not more than 1.13mm; the penetration depth of the sheath material at 60℃ is not more than 1.14mm.

7. The blown optical cable suitable for use in high temperature installation environments of claim 1, wherein, The outer diameter of the blown optical cable is 1.1mm to 4.2mm, and the sheath thickness is 0.2mm to 0.8mm.

8. The blown optical cable suitable for use in high temperature installation environments of claim 7 wherein, The compression deformation of the blown optical cable is less than 5% at 10℃ to 70℃.

9. The blown optical cable suitable for use in high temperature installation environments of claim 1, wherein, The cable body of the blown optical cable has a groove with a depth of more than 0.05mm, and the length of the sheath on the circumference of the maximum outer diameter of the sheath cross section is less than 50% of the circumference.

10. The blown optical cable suitable for use in high temperature installation environments of claim 9, wherein, The groove is a straight groove.

11. The method of installing a blown optical cable according to any one of claims 1 to 10, wherein It comprises the following steps: The blown optical cable is laid by air blowing method; A clamping force is applied to the input and output end of the cable, so that the compression deformation is less than 5%; A pushing force is applied to the input end; Compressed air is supplied to the input end; The air blowing working environment temperature is 0℃ to 45℃.

12. The method of installing a blown optical cable of claim 11, wherein, The clamping force is generally between 1 and 5N, the upper limit of the pushing force is less than or equal to 40N, and the upper limit of the compressed air pressure is 15BAR.

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