Device and method for threading electrical wire tube with strip wire based on negative pressure adsorption

Abstract

The invention provides an electrical line tube strip line threading device and method based on negative pressure adsorption. The device comprises a negative pressure generation assembly, a sealing connection assembly, a transition traction assembly and a flexible traction body connected to the transition traction assembly. Wherein the first end of the sealing connection assembly is connected with the air port of the negative pressure generation assembly, and the second end of the sealing connection assembly is used for being connected with a wire pipe to be threaded. The belt line threading logic of negative pressure adsorption and traction rope transition is created for the first time, the traditional manual pushing thinking form is broken through, rapid threading of the transition traction assembly is achieved through negative pressure suction force, then the belt line is indirectly driven through the transition traction assembly, and the technical bottleneck of manual threading of a long-distance multi-elbow line pipe is solved; through the sealing connection assembly of the negative pressure generation assembly and the to-be-threaded line pipe, the negative pressure environment stability is guaranteed, insufficient suction caused by air leakage is avoided, the smoothness of the penetrating process is guaranteed, and the connection mode is simple and reliable and is suitable for line pipes of different specifications.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrical installation engineering, in particular to an electrical conduit threading device and method based on negative pressure adsorption. BACKGROUND

[0002] In building electrical installation construction, conduit wiring is one of the core processes, and threading is a key step before conduit wiring, and its efficiency directly affects the overall construction progress. The traditional threading method commonly used in the industry has the following process: 1. Select two steel wires with a specification of 1.6-2.0 mm as the threading medium, bend one end of one of the steel wires into a closed circle, and bend one end of the other steel wire into an open hook; 2. The construction personnel manually thread the processed steel wire from both ends of the conduit (the ends of the circle and the hook are both inward), until the steel wires meet and collide in the conduit; 3. Two construction personnel operate at both ends of the conduit, respectively, and stir the steel wire in the opposite direction until the ends of the two steel wires are hooked and twisted, and then pull out one of the steel wires from the conduit in one direction (the first and last ends are guaranteed to be placed in the conduit), and the threading is completed; 4. After threading is completed, a cloth strip is tied to one end of the steel wire, and two construction personnel pull the steel wire back and forth at both ends of the conduit to remove dust, mud, debris and other impurities in the conduit, ensuring smooth subsequent cable threading.

[0003] However, the above traditional method has many defects: first, the threading efficiency is very low, and the manual threading process is prone to cause the steel wire to be stuck due to the bending of the conduit, rough inner wall or residual impurities, especially for long-distance (more than 5 meters) or multi-bending (2 or more bending sections) conduits, which often need to be adjusted repeatedly. The angle of the steel wire and tried many times to be successful, and the time consumption of single threading is usually 10-30 minutes; second, the labor cost is high, and at least two construction personnel are required to operate cooperatively for the threading and impurity cleaning process of long-distance or multi-bending conduits, which occupies more human resources; third, the steel wire is easily damaged, and the repeated friction between the steel wire and the inner wall of the conduit during the threading process easily causes the surface of the steel wire to rust and deform, and the steel wire cannot be used after being used many times, increasing the construction material cost; fourth, the operation is difficult, and for the conduit that is embedded in the wall or floor, the threading space is limited, and the precision of manual threading is difficult to control, further reducing the construction efficiency. SUMMARY

[0004] In view of this, the present application provides an electrical conduit threading device and method based on negative pressure adsorption, aiming to solve the problems of low threading efficiency, high labor intensity and unstable success rate in the existing electrical conduit threading technology.

[0005] In one aspect, the application provides an electrical cable tube threading device based on negative pressure adsorption, comprising: a negative pressure generating assembly, a sealed connection assembly, a transition traction assembly, and a flexible traction body connected to the transition traction assembly; wherein the first end of the sealed connection assembly is connected to the air inlet of the negative pressure generating assembly, and the second end of the sealed connection assembly is used to connect a to-be-threaded cable tube; the transition traction assembly is placed on one side of the to-be-threaded cable tube by negative pressure adsorption of the negative pressure generating assembly; under the action of negative pressure, the transition traction assembly passes through the to-be-threaded cable tube and is connected to the second end of the sealed connection assembly to form a traction link; the flexible traction body bound to the transition traction assembly is used for threading, thereby realizing the threading of the to-be-threaded cable.

[0006] Further, in the above-mentioned electrical cable tube threading device based on negative pressure adsorption, the negative pressure generating assembly is a dust collector, and a telescopic dust collection pipe is connected to the suction port of the dust collector.

[0007] Further, in the above-mentioned electrical cable tube threading device based on negative pressure adsorption, the sealed connection assembly is a rubber joint.

[0008] Further, in the above-mentioned electrical cable tube threading device based on negative pressure adsorption, the transition traction assembly comprises a binding rope and a reel; one end of the binding rope is bound to the reel, and the other end is a free end, which is used to pull the to-be-threaded cable to thread from the to-be-threaded cable tube.

[0009] Further, in the above-mentioned electrical cable tube threading device based on negative pressure adsorption, the binding rope is a polypropylene binding rope.

[0010] In another aspect, the application further provides an electrical cable tube threading method based on negative pressure adsorption, comprising the following steps: sealingly connecting the negative pressure generating assembly and the to-be-threaded cable tube through the sealed connection assembly; starting the negative pressure generating assembly to form a negative pressure environment in the to-be-threaded cable tube; sending the free end of the transition traction assembly into the to-be-threaded cable tube from the suction end of the negative pressure generating assembly, using the negative pressure in the to-be-threaded cable tube to drive the transition traction assembly to pass through the to-be-threaded cable tube until it is connected to the other side of the sealed connection assembly; closing the negative pressure generating assembly, cutting off the transition traction assembly for threading, and disconnecting the sealed connection assembly from the to-be-threaded cable tube; binding one end of the flexible traction body to one end of the cut-off transition traction assembly, pulling the other end of the transition traction assembly to pull the bound flexible traction body through the cable tube, so as to realize the threading of the to-be-threaded cable.

[0011] Further, in the above-mentioned electrical cable tube threading method based on negative pressure adsorption, the cut-off transition traction assembly is specifically: cutting off the transition traction assembly for threading, and reserving a predetermined traction length at both ends of the cable tube.

[0012] Further, the above-mentioned electrical conduit threading method based on negative pressure adsorption, the preset reserved traction length is 15-20 cm.

[0013] Further, the above-mentioned electrical conduit threading method based on negative pressure adsorption, the traction binding to be threaded line is threaded through the conduit, in particular, the traction binding to be threaded line is threaded through the conduit and a preset threading length is reserved at both ends of the conduit.

[0014] Further, the above-mentioned electrical conduit threading method based on negative pressure adsorption, the preset threading length is 10-15 cm.

[0015] The device and method for threading based on negative pressure adsorption provided by the application break through the traditional manual pushing mode of thinking, and utilize the negative pressure to realize the rapid threading of the transition traction assembly, and then indirectly drive the threading line through the transition traction assembly, so that the technical bottleneck of manual threading of the long-distance conduit with multiple bends is solved; and the sealing connection assembly of the negative pressure generating assembly and the conduit to be threaded ensures the stability of the negative pressure environment, avoids the insufficient suction caused by air leakage, and guarantees the smoothness of the threading process. The connection mode is simple and reliable, and is suitable for conduits with different specifications (inner diameter of 16-50 mm). The device can quickly drive the transition traction assembly to pass through the conduit to be threaded through the negative pressure adsorption force. No matter the length of the conduit (adapted to ≤20 meters of conduit) or the number of bends (adapted to ≤5 bends), the threading time is controlled within 1-2 minutes. Compared with the traditional manual method, the efficiency is improved by 10-20 times, and the efficiency is greatly improved. For large buildings and group buildings, this environment can save a lot of manpower, and solving this problem can save a lot of manpower cost for the project. At the same time, the construction personnel only need to operate the negative pressure generating assembly, the rope and the binding threading line, and do not need to bend down and push the threading line. A single person can complete all the operations, greatly reducing the physical consumption and labor intensity, and the construction personnel can quickly master the operation process without complex training.

[0016] Further, the polypropylene binding rope has good flexibility and light weight, is perfectly adapted to the negative pressure adsorption principle, can easily bypass the conduit bends, and has a certain "avoidance" ability to the slight impurities in the conduit. The threading success rate is ≥98%, which is much higher than that of the traditional method. Compared with the traditional steel threading line, the polypropylene binding rope is more easily driven by the negative pressure and is not easy to damage the conduit. BRIEF DESCRIPTION OF DRAWINGS

[0017] Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments with reference made to the accompanying drawings. The drawings are for purposes of illustration only and are not considered a limitation of the present application. Further, like reference numerals have been used throughout the drawings to designate like parts. In the drawings: Figure 1 A structural schematic diagram of the electrical conduit threading device based on negative pressure adsorption provided by an embodiment of the present application is shown in FIG. 1. Figure 2 A detailed flowchart of the electrical conduit threading method based on negative pressure adsorption provided by an embodiment of the present application is shown in FIG. 2. Figure 3 Another flowchart of the electrical conduit threading method based on negative pressure adsorption provided by an embodiment of the present application is shown in FIG. 3. Legend of reference signs: 1-negative pressure generating assembly, 11-dust suction pipe, 2-transition traction assembly, 3-waiting threading conduit, 31-conduit low port, 4-bundling rope, 5-illumination distribution box. DETAILED DESCRIPTION

[0018] Exemplary embodiments of the present disclosure will be described in greater detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the drawings, it is understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that the present disclosure can be more thoroughly understood and the scope of the present disclosure can be accurately conveyed to those skilled in the art. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0019] Reference is made to Figure 1 which is a structural schematic diagram of the electrical conduit threading device based on negative pressure adsorption provided by an embodiment of the present application. As shown in the figure, the device can include: a negative pressure generating assembly 1, a sealing connection assembly, and a transition traction assembly 2.

[0020] The first end of the sealing connection assembly is at the air port of the negative pressure generating assembly 1, and the second end of the sealing connection assembly is used to connect the waiting threading conduit 3. The waiting threading conduit 3 is placed on one side of the transition traction assembly 2 by the negative pressure adsorption of the negative pressure generating assembly 1. Under the action of negative pressure, the transition traction assembly 2 passes through the waiting threading conduit 3 and is docked with the second end of the sealing connection assembly to pass out, forming a traction link. The flexible traction body bound on the transition traction assembly 2 is threaded, thereby realizing the threading of the waiting threading conduit.

[0021] Specifically, the negative pressure generating assembly 1 is a dust collector, and a telescopic dust suction pipe 11 is connected to the suction port of the dust collector, facilitating adaptation to different construction scenes. The dust collector can be a high-power dust collector with a power of 1500W or more, having the characteristics of strong suction and stable operation. The sealing connection assembly can include rubber joints suitable for different inner diameters of the line pipe, such as six specifications of inner diameters of 16mm, 20mm, 25mm, 32mm, 40mm, and 50mm. One end of the rubber joint is tightly sleeved with the dust suction pipe 11 of the negative pressure generating assembly 1, and the other end can be tightly connected with the line pipe port, especially the low port 31 of the line pipe, of the line pipe to be threaded, ensuring that the negative pressure does not leak and avoiding air leakage. By starting the dust collector, a stable negative pressure environment is formed inside the line pipe to be threaded. The transition traction assembly 2 can be placed at the other end of the line pipe to be threaded, away from the sealing connection assembly, and can be adsorbed under the action of negative pressure inside the line pipe to be threaded, completing the threading of the transition traction assembly 2 and forming a traction link through the continued traction of the transition traction assembly 2, so as to pull the line to be threaded that is bound to the transition traction assembly 2 to complete the threading of the line to be threaded. One end of the sealing connection assembly is fixedly connected with the dust suction pipe 11 of the negative pressure generating assembly 1, and the other end can be detachably connected with one end of the line pipe to be threaded. The flexible traction body can be a conventional steel wire, such as a steel wire with a diameter of 1.2mm-1.5mm, which is used for subsequent traction of cables and wires. The line pipe to be threaded can also have a lighting distribution box 5 at the high port, which can realize threading of the wires in the lighting distribution box 5.

[0022] In the present embodiment, the transition traction assembly 2 includes a binding rope 4 and a wire reel. One end of the binding rope 4 is bound to the wire reel, and the other end is a free end, which is used to pull the line to be threaded from the line pipe to be threaded.

[0023] Specifically, the binding rope 4 can be a polypropylene binding rope 4 with a tensile strength of 50N or more and a length of 30 meters or more, which can be adapted to a line pipe of 20 meters or more in length. The wire reel is used to store the binding rope 4, facilitating simultaneous unwinding and feeding of the rope during construction. In the present embodiment, the polypropylene binding rope 4 is selected as the transition traction member, which has the characteristics of light weight, good flexibility, and low cost, and is perfectly adapted to the principle of negative pressure adsorption. Compared with the traditional steel wire directly threaded, it is easier to be driven by negative pressure and is less likely to damage the line pipe.

[0024] In summary, the electrical conduit threading device based on negative pressure adsorption provided in the embodiment creates the threading logic of "negative pressure adsorption + traction rope transition", breaks through the traditional manual pushing mindset, uses negative pressure to realize the rapid threading of the transition traction assembly 2, and then indirectly drives the threading rope through the transition traction assembly 2, solving the technical bottleneck of manual threading of long-distance multi-bend conduit; and, through the sealed connection assembly between the negative pressure generating assembly 1 and the conduit 3 to be threaded, the stability of the negative pressure environment is ensured, air leakage is avoided to cause insufficient suction, and the smoothness of the threading process is ensured. The connection method is simple and reliable, and is suitable for conduits of different specifications (inner diameter 16mm-50mm). The device can quickly drive the transition traction assembly 2 to pass through the conduit 3 to be threaded through the negative pressure adsorption force. Whether the length of the conduit (adapted to ≤20m conduit) or the number of bends (adapted to ≤5 bends), the threading time is controlled within 1-2 minutes. Compared with the traditional manual method, the efficiency is improved by 10-20 times, and the efficiency is greatly improved. For large buildings and group buildings, this environment will save a lot of manpower, and solving this problem will save a lot of manpower cost for the project; at the same time, the construction personnel only need to operate the negative pressure generating assembly 1, the rope feeding and binding, and do not need to bend down and push the threading rope, and a single person can complete all the operations, greatly reducing physical exertion and labor intensity, and without complex training, the construction personnel can quickly master the operation process.

[0025] Further, the polypropylene binding rope 4 has good flexibility and light weight, and is perfectly adapted to the negative pressure adsorption principle, can easily bypass the conduit bend, and has a certain "avoidance" ability for slight impurities inside the conduit, with a threading success rate ≥98%, which is much higher than the traditional method. Compared with the traditional steel threading rope, it is more easily driven by negative pressure and is not easy to damage the conduit.

[0026] Method embodiment: Referring to Figure 2 and Figure 3 , which shows the preferred flow chart of the electrical conduit threading method based on negative pressure adsorption provided by the embodiment of the application. As shown in the figure, the electrical conduit threading method based on negative pressure adsorption includes the following steps: Step S1, sealingly connecting the negative pressure generating assembly 1 and the conduit 3 to be threaded through the sealing connection assembly.

[0027] Specifically, a large-power vacuum cleaner with power not less than 1500W (to ensure sufficient negative pressure suction), a polypropylene bundling rope 4 with a diameter matching the inner diameter of the wire pipe (the diameter is 1 / 3-1 / 2 of the inner diameter of the wire pipe, light in weight and good in flexibility), a wire reel (for accommodating the polypropylene bundling rope 4) and a conventional steel wire are selected first. Then, one end of the sealing connection assembly is fixedly connected with the suction pipe 11 of the negative pressure generating assembly 1, and the other end is detachably connected with one end of the wire pipe 3 to be threaded, so as to ensure sealing and tight fit and prevent negative pressure leakage. In particular, the vacuum cleaner is placed at the low end of the wire pipe 3 to be threaded, and the sealing connection assembly (i.e. the pipe rubber head) of the vacuum cleaner is inserted into the pipe opening. The rubber head is ensured to be tightly fitted with the wire pipe, otherwise the rubber head is replaced or wound to ensure tight fit.

[0028] Step S2: The negative pressure generating assembly 1 is started to form a negative pressure environment inside the wire pipe 3 to be threaded.

[0029] Specifically, the vacuum cleaner is turned on to form a negative pressure environment inside the wire pipe 3 to be threaded.

[0030] Step S3: The free end of the transition traction assembly 2 is sent into the wire pipe 3 to be threaded from the suction end of the negative pressure generating assembly 1 away from the wire pipe 3 to be threaded, and the transition traction assembly 2 is driven to pass through the wire pipe 3 to be threaded by the negative pressure suction force inside the wire pipe 3 to be threaded until it is threaded out from the side of the sealing connection assembly.

[0031] Specifically, the polypropylene bundling rope is sent into the wire pipe 3 to be threaded from the high end of the wire pipe 3 to be threaded.

[0032] The polypropylene bundling rope 4 is driven to pass through the entire wire pipe by the negative pressure suction force inside the wire pipe until it is threaded out from the side of the suction pipe 11, i.e. it passes through the wire pipe under the action of negative pressure and is connected with the output end of the suction pipe 11.

[0033] Step S4: The negative pressure generating assembly 1 is turned off, the transition traction assembly 2 for threading is cut off, and the sealing connection assembly is detached from the wire pipe 3 to be threaded.

[0034] Specifically, the vacuum cleaner is turned off, and the polypropylene bundling rope is cut off. The transition traction assembly 2 for threading is cut off, and a predetermined reserved traction length is reserved at each end of the wire pipe. The predetermined reserved traction length is 15-20 cm.

[0035] Step S5: One end of the flexible traction body is tied with one end of the cut-off transition traction assembly, and the other end of the transition traction assembly is pulled to pull the tied flexible traction body through the wire pipe, so as to realize wire threading by pulling the wire to be threaded through the flexible traction body.

[0036] Specifically, the flexible traction body is pulled through the wire pipe to be threaded 3 by the transition traction assembly, and then the flexible traction body is pulled through the wire pipe to be threaded 3, that is, the flexible traction body is pulled through the wire pipe to be threaded 3 by the lashing rope, so as to prepare for the next threading, that is, one end of the lashing rope 4 of the transition traction assembly 2 is fixedly bound with the target belt line to form a traction link. The traction bound wire to be threaded passes through the wire pipe, specifically: the traction bound wire to be threaded passes through the wire pipe and reserves a preset threading length at both ends of the wire pipe. The preset threading length is 10-15 cm. Therefore, compared with directly pulling the guide wire by the transition traction assembly, it can be seen that it can be pulled off.

[0037] In summary, the electrical wire pipe threading method based on negative pressure adsorption provided by the embodiment breaks through the traditional manual pushing mode of thinking, realizes the rapid threading of the transition traction assembly 2 by using the negative pressure suction force, and then indirectly drives the belt line through the transition traction assembly 2, thereby solving the technical bottleneck of manual threading of long-distance wire pipes with multiple bends; and the sealing connection assembly of the negative pressure generating assembly 1 and the wire pipe to be threaded 3 ensures the stability of the negative pressure environment, avoids insufficient suction force due to air leakage, and ensures the smoothness of the threading process. The connection method is simple and reliable, and is suitable for wire pipes of different specifications (inner diameter 16-50 mm). The device can quickly drive the transition traction assembly 2 to pass through the wire pipe to be threaded 3 by the negative pressure adsorption force. Whether the length of the wire pipe (adapted to ≤20 meters of wire pipe) or the number of bends (adapted to ≤5 bends), the threading time is controlled within 1-2 minutes, which is 10-20 times more efficient than the traditional manual method, and the efficiency is greatly improved. For large buildings and group buildings, this environment will save a lot of manpower, and solving this problem will save a lot of manpower for the project; at the same time, the construction personnel only need to operate the negative pressure generating assembly 1, send the rope and bind the belt line, without the need to bend down and push the belt line, a single person can complete all the operations, greatly reducing physical exertion and labor intensity, and without the need for complex training, the construction personnel can quickly master the operation process.

[0038] Further, the polypropylene lashing rope 4 has good flexibility and light weight, and is perfectly adapted to the negative pressure adsorption principle, can easily bypass the wire pipe bend, and has a certain "avoidance" ability for slight impurities inside the wire pipe, with a threading success rate ≥98%, which is much higher than the traditional method. Compared with the traditional steel belt line directly threaded, it is more easily driven by negative pressure and less likely to damage the wire pipe.

[0039] It should be noted that in the description of the present application, the terms "upper", "lower", "left", "right", "inner", "outer" and the like indicate the direction or positional relationship of the terms based on the direction or positional relationship shown in the drawings, which is only for the convenience of description, and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation, therefore it cannot be understood as a limitation on the present application.

[0040] Furthermore, it needs to be explained that in the description of the present application, unless explicitly defined and limited, the terms "mounting", "connection", "connecting" should be understood in a broad sense, for example, can be fixed connection, can also be detachable connection, or integrally connected; can be directly connected, or indirectly connected through an intermediate medium, can be the communication inside 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.

[0041] Obviously, those skilled in the art can make various modifications and variations to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalent technologies, the present application also intends to include these modifications and variations.

Claims

1. A device for threading electrical conduits based on negative pressure adsorption, characterized in that, include: The system comprises a negative pressure generating component, a sealing connection component, a transition traction component, and a flexible traction body connected to the transition traction component; among which... The first end of the sealing connection component is connected to the air outlet of the negative pressure generating component, and the second end of the sealing connection component is used to connect to the conduit to be threaded. The transition traction component, which is placed on one side of the conduit to be threaded and fed in by the negative pressure of the negative pressure generating component, is used to attract the transition traction component. Under the action of negative pressure, the transition traction component passes through the conduit to be threaded and connects with the second end of the sealing connection component to exit, forming a traction link. The flexible traction body tied to the transition traction component is pulled to thread the wire, thereby realizing the threading of the wire to be threaded.

2. The electrical conduit threading device based on negative pressure adsorption according to claim 1, characterized in that, The negative pressure generating component is a vacuum cleaner, and its suction port is connected to a retractable suction hose.

3. The electrical conduit threading device based on negative pressure adsorption according to claim 1, characterized in that, The sealing connection assembly is a rubber joint.

4. The electrical conduit threading device based on negative pressure adsorption according to claim 1, characterized in that, The transition traction assembly includes a binding rope and a spool; wherein... One end of the binding rope is tied to the spool, and the other end is a free end, used to pull the wire to be threaded through the wire tube.

5. The electrical conduit threading device based on negative pressure adsorption according to claim 1, characterized in that, The binding rope is a polypropylene binding rope.

6. A method for threading electrical conduits using negative pressure adsorption, characterized in that, Includes the following steps: The negative pressure generating component is sealed to the conduit to be threaded using a sealing connection component; Activate the negative pressure generating component to create a negative pressure environment inside the conduit where the wires are to be threaded; The free end of the transition traction component is sent into the tube to be threaded from the suction end of the tube away from the negative pressure generating component. The negative pressure suction in the tube to be threaded is used to drive the transition traction component through the tube until it passes out from the side of the sealing connection component. Turn off the negative pressure generating component, disconnect the transition traction component for threading, and remove the sealing connection component from the conduit to be threaded; Tie one end of the flexible traction body to one end of the cut transition traction component, pull the other end of the transition traction component, and pull the tied flexible traction body through the conduit to achieve wire threading by pulling the line to be threaded through the flexible traction body.

7. The method for threading electrical conduits based on negative pressure adsorption according to claim 6, characterized in that, The transition traction assembly for cutting and threading is specifically: Cut the transition traction component of the wire thread and reserve a preset traction length at both ends of the conduit.

8. The method for threading electrical conduits based on negative pressure adsorption according to claim 6, characterized in that, The preset reserved traction length is 15-20cm.

9. The method for threading electrical conduits based on negative pressure adsorption according to claim 6, characterized in that, The cable to be threaded, which is to be pulled and bound, passes through the conduit, specifically as follows: The cable to be threaded is pulled and bound through the conduit, with a pre-set threading length reserved at both ends of the conduit.

10. The method for threading electrical conduits based on negative pressure adsorption according to claim 6, characterized in that, The preset thread length is 10-15cm.

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