CN116288915A - Knotless flexible windproof net with non-uniform porosity and preparation method thereof - Google Patents

Abstract

The invention relates to a knotless flexible windproof net with non-uniform porosity and a preparation method thereof. The knotless flexible windproof net is woven from polymer filament bundles, including a lower part and an upper part arranged along the longitudinal direction of coils; The porosity of the lower part is 31% to 34%, and the porosity of the upper part is 14% to 17%. The preparation method is: first weave the structure of the lower part by using a warp knitting machine equipped with an electronic traverse device, and then change the laying yarn The structure of the upper part is digitally woven to obtain a knotless flexible windproof net with non-uniform porosity; the product of the invention has good windproof and dust suppression effects and has buffering performance; the method of the invention is simple in process.

Description

Knotless flexible windproof net with non-uniform porosity and preparation method thereof

technical field

The invention belongs to the technical field of windproof structures for stockyards, and relates to a knotless flexible windproof net with non-uniform porosity and a preparation method thereof.

Background technique

The "Coal Dust Emission Coefficient Table for Coal Handling and Stockpiling" states that the coal dust discharged during the loading and unloading process of open-air storage coal dust is 3.53-6.41Kg/t coal/year, and the coal dust discharged during stockpiling is 1.48-2.02Kg /t coal/year. However, 80% of China's coal resources are distributed in the north and 10% in the southwest. The nine provinces, cities, and districts in the south of the Yangtze River with developed economies and concentrated energy consumption only account for 1.8%. Coal dust pollution, based on raw coal consumption of 500,000 tons per year, the value of coal dust discharged during loading and unloading is 6.41Kg/t coal/year, and 3,205 tons of coal dust is produced every year. As the country's environmental protection standards become increasingly strict, coal yards are also looking for technologies to reduce pollution emissions. Installing wind and dust suppression nets can not only protect the environment, but also reduce the loss of coal raw materials.

The wind-proof and dust-suppressing net is a wind-shielding facility with a certain porosity. With a certain porosity, it can not only attenuate the mechanical energy of the incoming wind to make it a low-speed flow, but also have a crushing effect on the larger vortex wind to reduce the pulsation speed of the wind. , reduce the coal pile dust rate. The wind speed of the incoming wind increases exponentially from low to high longitudinally in front of the net, and the turbulence intensity decreases exponentially from low to high. Behind the net, the circumventing wind is formed in the upper half of the downwind direction, and the seepage wind passes through the windproof net to form an attached flow going up the pile. Under the influence of a certain wind speed or porosity, the wind around the upper part will easily cause a longitudinal pressure difference to form a vortex flow. Excessive turbulence intensity and turbulence integral scale vortex flow will aggravate dust, while the lower part of the protective net has too low turbulence intensity. And the turbulent integral scale vortex flow is often accompanied by strong seepage wind, which increases the shear force on the pile surface. The greater the shear force on the pile surface, the more obvious the dust raising effect. Different windproof and dust suppression nets have different windproof and dust suppression effects. It is necessary to properly install and use the windproof and dust suppression nets to achieve the purpose of windproof and dust suppression.

Existing rigid windproof dust suppression net (also known as windbreak wall) and uniform porosity flexible windproof net technology. Rigid wind-proof and dust-suppressing mesh panels are made by punching holes on glass fiber reinforced plastic or metal material plates. Due to the lack of toughness, cracks are easy to appear after years of use. The steel plates are more likely to break under the impact of strong winds, which pose a certain threat to human safety. The windproof effect of the rigid windproof mesh with cracks is greatly reduced. Therefore, people try to weave flexible windproof nets with flexible filaments using warp knitting technology. The filaments are high-density polyethylene or polyester. The raw material cost is low, easy to transport, and the mechanical properties are heavy and flexible. Adding anti-UV agents, anti-aging agents, flame retardants, cross-linking enhancers, etc. can be flame-retardant and prolong the service life. However, the current woven flexible windproof nets are all uniform nets with a porosity of about 30%. Since the characteristic of the incoming wind is that the wind speed increases and the turbulence intensity decreases with the increase of the height from the ground, it cannot well adapt to the characteristics of the incoming wind.

For the incoming wind parallel to the ground and perpendicular to the windproof net, the wind speed increases exponentially from low to high at the upwind direction of the net, and the turbulence intensity decreases exponentially. However, the form of the wind flow field changes after passing through the windproof net. The form of the wind is mainly determined by the wind speed of the incoming wind, the mesh shape of the windproof net, and the porosity of the windproof net.

When the wind speed is low, the wind mostly passes through the windproof net in the form of seepage, which has a mild effect on the windproof net. Backlog, the wind pressure difference in front of the net and behind the net gradually increases, the force on the net begins to increase, and the flow around the net begins to increase; when the wind speed is extremely high, only a small part of the incoming wind enters the net in the form of seepage Finally, most of the wind goes up along the windproof net to the back of the net in the form of circumvention. In this case, the upper part of the back of the net will form a vortex flow with extremely high turbulence intensity. Too large and strong vortex flow will strengthen the wind behind the net. Dust rises from the top of the stockpile. It can be seen that under different wind speed conditions, the characteristics of the flow field along the longitudinal height of the windproof net after the wind interacts with the windproof net are different.

The mesh shape of the windproof net is compared with the typical trapezoidal, square and circular windproof effects. In the case of the same incoming wind, the wind speed, pressure and turbulent kinetic energy on the surface of the windproof net behind the circular mesh are better than those of the other two mesh shapes. The windproof net is small, that is, the dust effect on the stockpile is weak, and the dust can be effectively suppressed.

The porosity of the windproof net has an impact on the mechanics and windproof effect of the windproof net. In the research of windproof nets, the drag coefficient is usually used to measure the wind resistance of the windproof nets. When the wind speed is constant, the drag coefficient decreases with the increase of the opening ratio, because the resistance is proportional to the drag coefficient and the wind speed of the incoming wind. Therefore, the greater the drag coefficient and the wind speed of the incoming wind, the greater the wind resistance of the windproof net, which is an extremely test of the toughness of the windproof net. When the wind speed is constant, the uniform porosity increases from 0 to 1, and the comprehensive windproof effect behind the screen first increases and then decreases. A vortex flow is easily formed between the upper part of the screen and the stockpile, and the height gradually decreases but still Appears in the upper half and usually increases to about 30% when the swirl flow disappears. It can be seen that when the porosity of the windproof net is less than 30%, the impact on the wind field at the rear upper half of the windproof net is more obvious.

In order to overcome the technical problems, there is an urgent need for a flexible windproof net that can balance mechanical and windproof performance, has certain toughness and meets the characteristics of incoming wind, so as to improve the windproof and dust suppression effect of the flexible windproof net.

Contents of the invention

The purpose of the present invention is to solve the problems existing in the prior art, and provide a knotless flexible windproof net with non-uniform porosity and a preparation method thereof.

In order to achieve the above object, the technical scheme adopted in the present invention is as follows:

A knotless flexible windproof net with non-uniform porosity, woven by polymer filament bundles, including a lower part and an upper part arranged along the wale direction of the coil; the porosity of the lower part is 31% to 34%, and the upper part The porosity is 14% to 17%. After the windproof and dust suppression net is removed from the machine, the tension will be released, and its different positions will shrink to varying degrees. When the windproof net is installed on the windproof frame, different positions will also produce different tensions. Is the main factor affecting the mesh size, so the porosity is a range value.

As a preferred technical solution:

The above-mentioned knotless flexible windproof net with non-uniform porosity is an integrated molded piece.

A knotless flexible windproof net with non-uniform porosity as described above is a knotless net with non-uniform porosity; the knotless net has a larger Ductility, in the face of strong winds, it can effectively buffer the impact of wind pressure. Under the same Reynolds number in the flow field, the resistance coefficient of unknotted nets is smaller than that of knotted nets. The knotted net is less stressed than the flexible knotted net, and the safety factor is improved, and the knot of the knotted net is a dead knot, and the bending of the node under the action of an external force makes the extrusion at the node stronger and the force is more concentrated, that is, there is The breaking strength at the knots of the knotted net is lower than that of the knotless net, and the knotless net used in the present invention has a greater breaking strength at the knots.

A kind of non-knot flexible windproof net with non-uniform porosity as mentioned above, the knot-free flexible wind-proof net with non-uniform porosity is made of high-density polyethylene filament bundle (by including but not limited to 4 high-density Polyethylene filaments) are woven by warp knitting machines. Considering the high strength and low cost of high-density polyethylene filaments, it is suitable for flexible windproof nets. At the same time, considering that the number of filaments is small, the bearing capacity is not enough, and the number is not large. It is convenient to weave, so the preferred non-knot flexible windproof net with non-uniform porosity in the present invention is obtained by weaving high-density polyethylene filament bundles through a warp knitting machine.

In the above-mentioned knotless flexible windproof net with non-uniform porosity, the fineness of high-density polyethylene filaments is 290-400 deniers.

As mentioned above, a knotless flexible windproof net with non-uniform porosity, the ideal forming model of the warp knitted net is: the lower mesh is a regular hexagonal hexagonal mesh, the upper mesh is a flat hexagonal hexagonal mesh, and the flat hexagonal mesh is flat. The hexagon is a hexagon with an inscribed ellipse, and the height of the upper mesh is smaller than that of the lower mesh; the present invention installs the regular hexagonal hexagonal mesh part with larger porosity under the windproof net frame, and the smaller porosity The flat hexagonal hexagonal mesh part is installed on the top of the windproof net frame, thereby enhancing the windproof and dust suppression effect of the windproof and dust suppression net; due to the use of warp knitting technology to weave small meshes, technical limitations make it impossible for the mesh to be completely round shape, the hexagonal mesh weaving structure adopted by the present invention can fit the circular hole as much as possible, and can improve the effect of windproof and dust suppression compared with meshes of other shapes such as square mesh; comprehensively considering the convenience of the weaving process and the mesh foot Uniformity of load-bearing, using a combination of hexagonal meshes of different shapes and sizes for weaving design, without additional drawing-in and warping work, it can be continuously carried out between one hexagonal mesh structure and another hexagonal mesh structure Weaving conversion reduces manpower consumption and saves production time.

A knotless flexible windproof net with non-uniform porosity as described above, the diameter of the inscribed circle of the regular hexagon is 3.5-4.5 mm; the length of the horizontal axis of the inscribed ellipse of the flat hexagon is 3.5-4.5 mm , the length of the longitudinal axis is 1.5-2mm; the spacing of the lower mesh is 2.5-3.5mm, the spacing of the upper mesh along the course direction is 2.5-3.5mm, and the spacing along the wale direction is 4-5mm; The number of mesh holes per 2 inches in the row direction is 6 to 8, and the number of mesh holes per 2 inches along the wale direction of the coil is 7 to 9; the number of mesh holes per 2 inches in the upper part along the direction of the coil row is 6 to 8. The number of mesh holes per 2 inches along the wale direction of the coil is 7 to 9; these values are the result of digital weaving according to the designed lap yarn, which can ensure that the porosity of the lower part of the flexible windproof net is 31% to 34%. , the upper porosity is 14% to 17%; this is why it is necessary to set "the height of the upper mesh is smaller than the height of the lower mesh". The size and shape of the meshes have been successfully changed by changing the lapping numbers of the bars, that is, since the lapping numbers of the remaining three bars have not changed, the mesh distribution density has not changed.

A knotless flexible windproof net with non-uniform porosity as described above, in the longitudinal direction, the height ratio of the lower part and the upper part along the coil wale direction is 1:1, and the height ratio of the two parts in the present invention is based on the winding The vertical influence range of the flow wind is determined at the downwind direction of the knotless flexible windproof net.

A knotless flexible windproof net with non-uniform porosity as described in any one of the above, the knotless flexible windproof net with non-uniform porosity is tested in the dense mesh safety vertical net of "GB5725-2009 Safety Net" The longitudinal breaking strength × breaking elongation detected under the standard is 200-240KN·mm, and the transverse breaking strength×breaking elongation is 45-65KN·mm. It can be seen that its mechanical properties are good and meet the evaluation requirements of impact resistance in this standard , it will not produce damage and tearing under strong wind conditions; the dust suppression rate of the non-knot flexible windproof net with non-uniform porosity (the area of the stockpile surface below a certain wind speed value after passing through the net divided by the total amount of the stockpile calculated surface area) is above 85%.

The present invention also provides a method for preparing a knotless flexible windproof net with non-uniform porosity as described in any one of the above items, using a warp knitting machine equipped with an electronic traverse device to weave the lower tissue structure first, and then through Changing the number of lapping yarns (only need to change the traversing pitch of the number of lapping yarns without changing the threading mode) weaves the structure of the upper part to make a knotless flexible windproof net with non-uniform porosity.

The present invention adopts continuous sheet weaving. Compared with weaving meshes with different uniform porosities first and then sewing and installing them, there is a connection between the different uniform porosities of the continuously woven flexible windproof net when it is stressed, that is, the adjacent meshes and the meshes are connected. When the filaments between the feet are under stress, part of the yarns will be transformed into each other, which is beneficial to balance the stress between each node and the mesh feet. The larger the continuously woven mesh, the more conducive to balance and ease the stress, making it flexible The windproof net has improved cushioning ability against wind. And the continuous piece weaving does not need to install corresponding facilities for stitching and splicing. It only needs to fix and connect the columns on both sides of the mesh, which reduces the expenditure of manpower, material and financial resources, and saves time and cost.

As a preferred technical solution:

In the above method, the lower part and the upper part have five combs participating in weaving, the GB1 threading mode is full threading, and the rest of the bar threading modes are 1 threading and 1 empty, wherein the lapping yarn of the lower part The numbers are:

GB1: 1-0/0-1/1-0/0-1 //; GB2: 0-0/2-2/3-3/1-1 //;

GB3: 3-3/1-1/0-0/2-2//; GB4: 0-0/1-1/3-3/2-2//; GB5: 3-3/2-2/ 0-0/1-1 //;

The number of lap yarns on the top is:

GB1: 1-0/0-1/1-0/0-1 //; GB2: 0-0/2-2/3-3/1-1 //;

GB3: 3-3/1-1/0-0/2-2//; GB4: 0-0/2-2/5-5/3-3//; GB5: 5-5/3-3/ 0-0/2-2 //;

The shape of the knotless flexible windproof mesh with non-uniform porosity is formed by inserting weft and pulling the warp knitting chain structure with four guide bars, and the weft-inserted tow woven by four guide bars forms a reinforced structure , to connect adjacent warp-knitted chains.

Principle of the present invention is as follows:

Compared with the existing flexible windproof net with uniform porosity, the non-uniform porosity flexible windproof net adopted in the present invention has different porosity in the upper and lower parts of the net sheet, the porosity of the upper part is 14% to 17%, and the porosity is less than 30%. Raise the height of the vortex flow that may be formed in the upper part of the windproof net when it is subjected to strong winds. The raised vortex flow will have a smaller impact on the flat top of the stockpile. The porosity of the lower part is 31% to 34%. %, a porosity slightly greater than 30% reasonably controls the seepage of the incoming wind, reduces the shear force of the incoming wind on the windward side of the stockpile, and also weakens the pressure difference between the front and rear wind pressure of the knotless flexible windproof net, that is It can reduce the force on the lower part of the windproof net. This porosity has a better windproof effect and can adapt to most application scenarios. The combination of different porosities on the top and bottom of the non-uniform porosity flexible windproof net reasonably controls the air flow field. The ratio of the circumventing wind to the seepage wind can effectively suppress the dust. In addition, due to the difference in organizational structure, there are two weft-inserted yarns on the half of the windproof and dust-suppressing net spanning 5 stitches, which makes the upper half of the structure stronger and less prone to deformation, that is, the stability of the half of the net. , firmness, and stretch resistance are better than the lower half, and when strong winds come, the wind resistance of the half of the net is better than that of the lower half. The characteristics of the incoming wind are that the higher the distance from the ground, the greater the wind speed. The greater the wind speed and the larger the area of the windproof mesh, the greater the force on the windproof mesh. This organizational structure is in line with the characteristics of the incoming wind. power situation. However, the uniform porosity flexible windproof net in the prior art is a single net with a uniform porosity of 30%. The windproof and dust suppression net with uniform porosity cannot well consider the law of airflow movement and turbulent structure on site. The exponential growth of the height from the ground will cause the knotless flexible windproof net to bear more load than the location. The mechanical properties of the upper part of the windproof net under strong wind are relatively weak, and the height of the center of the vortex flow that may be formed under strong wind Compared with the height of the non-uniform porosity flexible windproof net of the present invention, the effect of windproof and dust suppression on the flat top of the stockpile is not strong, that is, it often cannot take into account the stress and dust suppression effects of the upper and lower parts of the stockpile at the same time, resulting in windproof and dust suppression. The dustproof effect of the dust net is not ideal.

Compared with the existing rigid windproof and dust suppression net, the non-uniform porosity flexible windproof net used in the present invention is woven from polymer filaments. In terms of mechanics, polymer filaments have higher strength than glass steel plates and metal plates. Toughness, better shear resistance, and the woven mesh is more flexible, tougher, and lighter than the glass steel plate or metal plate punching mesh. When receiving uneven wind force, it can also use the stress transmission between the mesh foot and the mesh to balance the stress on each part. In the prior art, the rigid windproof net material itself is bulky, and it will test the load-bearing capacity of the steel frame of the windproof net when the strong wind strikes. To increase the safety factor, the installation of the steel frame will also increase the cost, and due to the shear resistance of the material itself Weak, not strong toughness, the windproof board is easy to crack or even break after a period of use, and the windproof ability is weakened under strong winds, and it also poses a great threat to human life. When the rigid windproof net is subjected to the incoming wind of uneven wind force, because it is spliced with mesh pieces, it cannot be balanced through the stress transfer between the mesh pieces. The unbalanced force of the entire rigid windproof net will also increase the strength of the net And the burden of the steel frame, the risk factor rises. Compared with the existing rigid windproof and dust suppression net, the non-uniform porosity flexible windproof net has lower cost, better toughness, and is safer under strong wind. Performance is better. In terms of wind-proof mechanism, since the wind-proof and dust-suppressing net of the present invention is woven from filament bundles, the mesh feet and meshes in the weaving net after getting off the machine will have a certain relaxation effect due to the decrease in tension, that is, the filaments There are tiny gaps between them. Under weak wind conditions, there is a certain degree of looseness between the tows in the knotless flexible windproof net, which makes the porosity of the flexible net slightly decrease, and because there are tiny gaps between the filaments , part of the incoming wind from the filaments through the net to the back of the net hedges against each other to weaken the kinetic energy; when the wind is strong, there is tension in the tow in the knotless flexible windproof net, and the tension makes the filaments only fit together. At this time The porosity of the flexible windproof net increases slightly, which is consistent with the scientific research results that the greater the wind speed of the incoming wind within a certain range of porosity, the better the dust suppression effect of the windproof net and dust suppression net with the greater porosity, while the rigid windproof dust suppression net is It is made of punched steel plate, the porosity is fixed so that the wind blocking effect cannot be improved with the size of the wind, and the flexible wind-proof net that tightly fits the tow under strong winds is compared with the rigid wind-proof and dust-suppressing net with the same porosity. Compared with the rigid windproof and dust suppression net, its surface roughness is greater than that of the rigid windproof and dust suppression net, which weakens the wind kinetic energy at the windproof net to a certain extent, and is beneficial to suppress the dust near the stockpile; finally, as shown in Figure 1, the non-uniform porosity knot-free flexible The windproof net 2 is supported by the steel frame 3 and installed in the upwind direction, so that the positional relationship placed can also weaken the effect of the incoming wind 1 on the material pile 4 in the downwind direction.

Beneficial effect

(1) A knotless flexible windproof net with non-uniform porosity of the present invention has better windproof and dust suppression effects, is simple to install, light and thin, has cushioning performance and is easy to transport;

(2) The method of the present invention has simple and convenient technology.

Description of drawings

Fig. 1 is a schematic diagram of the relationship between a knotless flexible windproof net with non-uniform porosity of the present invention and incoming wind and stockpile;

Fig. 2 is a motion diagram of the warp knitting process yarn lap yarn in the lower part of the knotless flexible windproof net with non-uniform porosity of the present invention;

Fig. 3 is an upper warp knitting process yarn laying motion diagram in a knotless flexible windproof net with non-uniform porosity of the present invention;

Among them, 1-incoming wind, 2-non-uniform porosity flexible windproof net, 3-windproof net steel frame, 4-stockpile.

Detailed ways

The present invention will be further described below in combination with specific embodiments. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the teachings of the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of the present application.

A method for preparing a knotless flexible windproof net with non-uniform porosity, as shown in Figures 2-3, the specific steps are as follows:

(1) Preparation of raw materials;

High-density polyethylene filaments with a fineness of 290-400 denier;

(2) Weave the structure of the lower part from high-density polyethylene filament bundles, and then digitally weave the structure of the upper part by changing the lapping yarn to obtain a knotless flexible windproof net with non-uniform porosity;

Among them, there are five bars in the lower and upper parts to participate in weaving. The threading method of GB1 is full threading, and the threading method of the other bars is 1 threading and 1 empty. Among them, the number of lapped yarns in the lower part is:

GB1: 1-0/0-1/1-0/0-1 //; GB2: 0-0/2-2/3-3/1-1 //;

GB3: 3-3/1-1/0-0/2-2//; GB4: 0-0/1-1/3-3/2-2//; GB5: 3-3/2-2/ 0-0/1-1 //;

The lapping numbers on the upper part are:

GB1: 1-0/0-1/1-0/0-1 //; GB2: 0-0/2-2/3-3/1-1 //;

GB3: 3-3/1-1/0-0/2-2//; GB4: 0-0/2-2/5-5/3-3//; GB5: 5-5/3-3/ 0-0/2-2//.

The finally obtained knotless flexible windproof net with non-uniform porosity is a one-piece molded piece and has no knot netting. It is woven from polymer filament bundles and consists of a lower part and an upper part arranged along the wale direction of the coil; the ideal state The lower and lower meshes are regular hexagonal hexagonal meshes, the upper meshes are flat hexagonal hexagonal meshes, and the flat hexagonal shape is a hexagon with an inscribed ellipse; the diameter of the inscribed circle of a regular hexagon is 3.5-4.5mm ; The length of the horizontal axis of the inscribed ellipse of the flat hexagon is 3.5-4.5 mm, and the length of the vertical axis is 1.5-2 mm; the distance between the meshes in the lower part is 2.5-3.5 mm, and the distance between the meshes in the upper part along the direction of the coil course is 2.5-2 mm; 3.5mm, the spacing along the wale direction is 4-5mm; the number of mesh holes per 2 inches along the course direction of the lower part is 6-8, and the number of mesh holes per 2 inches along the wale direction is 7-9; The number of mesh holes per 2 inches along the course direction of the upper part is 6 to 8, and the number of mesh holes per 2 inches along the direction of the wale is 7 to 9; in the longitudinal direction, the height ratio of the lower part and the upper part along the wale direction The ratio is 1:1; the porosity of the lower part is 31% to 34%, and the porosity of the upper part is 14% to 17%; the knotless flexible windproof net with non-uniform porosity is listed in "GB5725-2009 Safety Net" The vertical breaking strength × breaking elongation detected under the standard safety vertical net test standard is 200-240KN·mm, and the transverse breaking strength×breaking elongation is 45-65KN·mm, and meets the evaluation requirements for impact resistance in this standard; The dust suppression rate of the knotless flexible windproof net with non-uniform porosity is over 85%.

Example 1

A method for preparing a knotless flexible windproof net with non-uniform porosity, the specific steps are as follows:

(1) Preparation of raw materials;

High-density polyethylene filaments with a fineness of 290 denier;

(2) After merging 4 high-density polyethylene filaments, use a warp knitting machine with a machine number of E12 to weave the structure of the lower part, and then digitally weave the structure of the upper part by changing the lapping yarn to obtain a non-uniform porosity Knotless flexible windproof net;

Among them, there are five bars in the lower and upper parts to participate in weaving. The threading method of GB1 is full threading, and the threading method of the other bars is 1 threading and 1 empty. Among them, the number of lapped yarns in the lower part is:

GB1: 1-0/0-1/1-0/0-1 //; GB2: 0-0/2-2/3-3/1-1 //;

GB3: 3-3/1-1/0-0/2-2//; GB4: 0-0/1-1/3-3/2-2//; GB5: 3-3/2-2/ 0-0/1-1 //;

The lapping numbers on the upper part are:

GB1: 1-0/0-1/1-0/0-1 //; GB2: 0-0/2-2/3-3/1-1 //;

GB3: 3-3/1-1/0-0/2-2//; GB4: 0-0/2-2/5-5/3-3//; GB5: 5-5/3-3/ 0-0/2-2//.

The finally obtained knotless flexible windproof net with non-uniform porosity is a one-piece molded piece and has no knot netting. It is woven from polymer filament bundles and consists of a lower part and an upper part arranged along the wale direction of the coil; the ideal state The lower and lower meshes are regular hexagonal hexagonal meshes, the upper meshes are flat hexagonal hexagonal meshes, and the flat hexagonal shape is a hexagon with an inscribed ellipse; the diameter of the inscribed circle of a regular hexagon is 3.5-4.5mm ; The length of the horizontal axis of the inscribed ellipse of the flat hexagon is 3.5-4.5 mm, and the length of the vertical axis is 1.5-2 mm; the distance between the meshes in the lower part is 2.5-3.5 mm, and the distance between the meshes in the upper part along the direction of the coil course is 2.5-2 mm; 3.5mm, the spacing along the wale direction is 4-5mm; the number of mesh holes per 2 inches along the course direction of the lower part is 6-8, and the number of mesh holes per 2 inches along the wale direction is 7-9; The number of mesh holes per 2 inches along the course direction of the upper part is 6 to 8, and the number of mesh holes per 2 inches along the direction of the wale is 7 to 9; in the longitudinal direction, the height ratio of the lower part and the upper part along the wale direction The ratio is 1:1; the porosity of the lower part is 31% to 34%, and the porosity of the upper part is 14% to 17%; the knotless flexible windproof net with non-uniform porosity is listed in "GB5725-2009 Safety Net" The vertical breaking strength × breaking elongation detected under the standard safety net test standard is 200KN mm, and the transverse breaking strength × breaking elongation is 45KN mm, which meets the evaluation requirements of impact resistance in this standard; it has non-uniform pores The high-efficiency knotless flexible windproof net is combined with the speed measurement on the surface of the coal pile and the calculation formula of the dust volume of the coal pile to obtain a dust suppression rate of 85%.

Comparative example 1

A flexible windproof net with uniform porosity is basically the same as the knotless flexible windproof net with non-uniform porosity in Example 1, except that the lower part is the same as that of the flexible windproof net with uniform porosity in Comparative Example 1. Both the lower part and the upper part are the same as the upper part of the knotless flexible windproof net with non-uniform porosity in Example 1.

The flexible windproof net with uniform porosity is combined with the speed measurement on the surface of the coal pile and the calculation formula of the dust emission of the coal pile to obtain a dust suppression rate (the test method and test conditions are the same as in Example 1) to be 60%.

Comparing Example 1 with Comparative Example 1, it can be seen that the windproof effect of the knotless flexible windproof net of Comparative Example 1 is not as good as the windproof effect of the knotless flexible windproof net of Example 1. This is because the pores of the whole piece of windproof net If the rate is too low, most of the seepage wind in the middle and lower part of the knotless flexible windproof net is blocked in front of the net, so that more air volume in front of the net passes through the back of the net in the form of turbulent wind, thereby increasing the wind speed of the circumventing wind, and due to The wind pressure in the middle and lower part of the net behind the net is too low, and the wind pressure above the net behind is too high, resulting in enhanced airflow disturbance in the longitudinal direction behind the net, and excessive turbulence intensity, thus forming a vortex flow wind with high wind speed and large area, which will greatly Intensify the level of dust on the flat top of the stockpile behind the net.

Comparative example 2

A flexible windproof net with uniform porosity is basically the same as the knotless flexible windproof net with non-uniform porosity in Example 1, the difference is only in the upper part, and the flexible windproof net with uniform porosity in Comparative Example 2 Both the upper part and the lower part are the same as the lower part of the knotless flexible windproof net with non-uniform porosity in Example 1.

The flexible windproof net with uniform porosity is combined with the speed measurement on the surface of the coal pile and the calculation formula of the dust volume of the coal pile to obtain a dust suppression rate (the test method and test conditions are the same as in Example 1) to be 75%.

Comparing Example 1 with Comparative Example 2, it can be seen that the windproof effect of the knotless flexible windproof net of Comparative Example 2 is not as good as the windproof effect of the knotless flexible windproof net of Example 1, because half of the porosity of the windproof net is Increase, lower the center of the vortex flow, so that a larger area of the surface of the stockpile is affected by the vortex flow, thereby increasing the effect of dust on the surface of the stockpile.

Comparative example 3

A metal plate punching net, the structure of which is the same as the knotless flexible windproof net with non-uniform porosity in Example 1.

The metal plate perforated net cooperates with the speed measurement on the surface of the coal pile and the calculation formula of the dust emission of the coal pile to obtain a dust suppression rate (the test method and test conditions are the same as in Example 1) to be 80%.

Comparing Example 1 with Comparative Example 3, it can be seen that the windproof effect of the knotless flexible windproof net of Comparative Example 3 is not as good as the windproof effect of the knotless flexible windproof net of Example 1. The rate is fixed so that the wind blocking effect cannot be improved with the size of the wind, and the porosity of the knotless flexible windproof net increases slightly under the action of the wind, which is consistent with the larger the wind speed within a certain range of porosity. The larger the windproof net, the better the dust suppression effect of the scientific research results, and its surface roughness is greater than that of the rigid windproof dust suppression net, which weakens the wind kinetic energy at the windproof net to a certain extent, which is conducive to suppressing the dust near the stockpile .

Example 2

A method for preparing a knotless flexible windproof net with non-uniform porosity, the specific steps are as follows:

(1) Preparation of raw materials;

High-density polyethylene filaments with a fineness of 340 denier;

(2) After merging 4 high-density polyethylene filaments, use a warp knitting machine with a machine number of E12 to weave the structure of the lower part, and then digitally weave the structure of the upper part by changing the lapping yarn to obtain a non-uniform porosity Knotless flexible windproof net;

Among them, there are five bars in the lower and upper parts to participate in weaving. The threading method of GB1 is full threading, and the threading method of the other bars is 1 threading and 1 empty. Among them, the number of lapped yarns in the lower part is:

GB1: 1-0/0-1/1-0/0-1 //; GB2: 0-0/2-2/3-3/1-1 //;

GB3: 3-3/1-1/0-0/2-2//; GB4: 0-0/1-1/3-3/2-2//; GB5: 3-3/2-2/ 0-0/1-1 //;

The lapping numbers on the upper part are:

GB1: 1-0/0-1/1-0/0-1 //; GB2: 0-0/2-2/3-3/1-1 //;

GB3: 3-3/1-1/0-0/2-2//; GB4: 0-0/2-2/5-5/3-3//; GB5: 5-5/3-3/ 0-0/2-2//.

The finally obtained knotless flexible windproof net with non-uniform porosity is a one-piece molded piece and has no knot netting. It is woven from polymer filament bundles and consists of a lower part and an upper part arranged along the wale direction of the coil; the ideal state The lower and lower meshes are regular hexagonal hexagonal meshes, the upper meshes are flat hexagonal hexagonal meshes, and the flat hexagonal shape is a hexagon with an inscribed ellipse; the diameter of the inscribed circle of a regular hexagon is 3.5-4.5mm ; The length of the horizontal axis of the inscribed ellipse of the flat hexagon is 3.5-4.5 mm, and the length of the vertical axis is 1.5-2 mm; the distance between the meshes in the lower part is 2.5-3.5 mm, and the distance between the meshes in the upper part along the direction of the coil course is 2.5-2 mm; 3.5mm, the spacing along the wale direction is 4-5mm; the number of mesh holes per 2 inches along the course direction of the lower part is 6-8, and the number of mesh holes per 2 inches along the wale direction is 7-9; The number of mesh holes per 2 inches along the course direction of the upper part is 6 to 8, and the number of mesh holes per 2 inches along the direction of the wale is 7 to 9; in the longitudinal direction, the height ratio of the lower part and the upper part along the wale direction The ratio is 1:1; the porosity of the lower part is 31% to 34%, and the porosity of the upper part is 14% to 17%; the knotless flexible windproof net with non-uniform porosity is listed in "GB5725-2009 Safety Net" The vertical breaking strength × breaking elongation detected under the standard safety net test standard is 225KN mm, and the transverse breaking strength × breaking elongation is 53KN mm, which meets the evaluation requirements of impact resistance in this standard; it has non-uniform pores The high-efficiency knotless flexible windproof net is combined with the speed measurement on the surface of the coal pile and the calculation formula of the dust volume of the coal pile to obtain a dust suppression rate of 85%.

Example 3

A method for preparing a knotless flexible windproof net with non-uniform porosity, the specific steps are as follows:

(1) Preparation of raw materials;

High-density polyethylene filaments with a fineness of 400 denier;

(2) After merging 4 high-density polyethylene filaments, use a warp knitting machine with a machine number of E12 to weave the structure of the lower part, and then digitally weave the structure of the upper part by changing the lapping yarn to obtain a non-uniform porosity Knotless flexible windproof net;

Among them, there are five bars in the lower and upper parts to participate in weaving. The threading method of GB1 is full threading, and the threading method of the other bars is 1 threading and 1 empty. Among them, the number of lapped yarns in the lower part is:

GB1: 1-0/0-1/1-0/0-1 //; GB2: 0-0/2-2/3-3/1-1 //;

GB3: 3-3/1-1/0-0/2-2//; GB4: 0-0/1-1/3-3/2-2//; GB5: 3-3/2-2/ 0-0/1-1 //;

The lapping numbers on the upper part are:

GB1: 1-0/0-1/1-0/0-1 //; GB2: 0-0/2-2/3-3/1-1 //;

GB3: 3-3/1-1/0-0/2-2//; GB4: 0-0/2-2/5-5/3-3//; GB5: 5-5/3-3/ 0-0/2-2//.

The finally obtained knotless flexible windproof net with non-uniform porosity is a one-piece molded piece and has no knot netting. It is woven from polymer filament bundles and consists of a lower part and an upper part arranged along the wale direction of the coil; the ideal state The lower and lower meshes are regular hexagonal hexagonal meshes, the upper meshes are flat hexagonal hexagonal meshes, and the flat hexagonal shape is a hexagon with an inscribed ellipse; the diameter of the inscribed circle of a regular hexagon is 3.5-4.5mm ; The length of the horizontal axis of the inscribed ellipse of the flat hexagon is 3.5-4.5mm, and the length of the longitudinal axis is 1.5-2mm; the spacing of the meshes in the lower part is 2.5-3.5mm, and the spacing of the meshes in the upper part along the direction of the coil course is 2.5-2mm. 3.5mm, the spacing along the wale direction is 4-5mm; the number of mesh holes per 2 inches along the course direction of the lower part is 6-8, and the number of mesh holes per 2 inches along the wale direction is 7-9; The number of mesh holes per 2 inches along the course direction of the upper part is 6 to 8, and the number of mesh holes per 2 inches along the direction of the wale is 7 to 9; in the longitudinal direction, the height ratio of the lower part and the upper part along the wale direction 1:1; the porosity of the lower part is 31% to 34%, and the porosity of the upper part is 14% to 17%; the knotless flexible windproof net with non-uniform porosity is listed in "GB5725-2009 Safety Net" The vertical breaking strength × breaking elongation detected under the standard safety net test standard is 240KN mm, and the transverse breaking strength × breaking elongation is 65KN mm, which meets the evaluation requirements of impact resistance in this standard; it has non-uniform pores The high-efficiency knotless flexible windproof net is combined with the speed measurement on the surface of the coal pile and the calculation formula of the dust volume of the coal pile to obtain a dust suppression rate of 85%.

Claims (9)

1. A knotless, flexible, windproof net having a non-uniform porosity, woven from polymeric filament bundles, comprising a lower portion and an upper portion aligned in the wale direction of the loop; the porosity of the lower part is 31% -34%, and the porosity of the upper part is 14% -17%.

2. A knotless, flexible, windproof net with non-uniform porosity according to claim 1, characterised in that the knotless, flexible, windproof net with non-uniform porosity is an integral piece.

3. A knotless flexible wind-resistant net having non-uniform porosity according to claim 2, wherein the knotless flexible wind-resistant net having non-uniform porosity is a knotless net.

4. A knotless, flexible, windproof net with non-uniform porosity according to claim 3, characterized in that it is obtained by knitting high-density polyethylene filaments with a warp knitting machine; the fineness of the high-density polyethylene filaments is 290-400 denier.

5. A knotless, flexible wind-resistant mesh having non-uniform porosity according to claim 1, wherein the lower cells are regular hexagonal cells, the upper cells are flat hexagonal cells, the flat hexagonal cells are hexagons having an inscribed ellipse, and the height of the upper cells is less than the height of the lower cells.

6. A knotless, flexible wind-resistant net having non-uniform porosity according to claim 1, wherein the ratio of the heights of the lower portion and the upper portion in the wale direction of the coil is 1:1 in the machine direction.

7. A knotless flexible wind-resistant net with non-uniform porosity according to any of claims 1 to 6, wherein the knotless flexible wind-resistant net with non-uniform porosity has a longitudinal breaking strength x elongation at break of 200-240 KN-mm, a transverse breaking strength x elongation at break of 45-65 KN-mm, and meets the evaluation requirements of impact resistance in the standard of the closed mesh safety vertical net test standard of GB5725-2009 safety net; the dust suppression rate of the knotless flexible wind-proof net with non-uniform porosity is more than 85%.

8. A method for preparing a knotless flexible wind-resistant net having non-uniform porosity according to any one of claims 1 to 7, wherein the knotless flexible wind-resistant net having non-uniform porosity is prepared by knitting the lower weave structure by a warp knitting machine equipped with an electronic traversing device and then knitting the upper weave structure by changing a yarn-laying number.

9. The method of claim 8, wherein the lower portion and the upper portion each have five bars involved in knitting, the GB1 thread-through is full, the remaining bars are 1 thread-through 1 empty, and wherein the lower portion has a fill-in number of:

GB1：1-0/0-1/1-0/0-1//；GB2：0-0/2-2/3-3/1-1//；

GB3：3-3/1-1/0-0/2-2//；GB4：0-0/1-1/3-3/2-2//；GB5：3-3/2-2/0-0/1-1//；

the upper yarn padding numbers are as follows:

GB1：1-0/0-1/1-0/0-1//；GB2：0-0/2-2/3-3/1-1//；

GB3：3-3/1-1/0-0/2-2//；GB4：0-0/2-2/5-5/3-3//；GB5：5-5/3-3/0-0/2-2//。

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