54 results about "Spiral wound" patented technology

The invention relates to the technical field of heat exchangers, and discloses a control method and system for a spiral wound tube type heat exchanger based on the Internet of Things. The method comprises the following steps: acquiring flow velocity distribution data in a pipe in real time through a multi-point sensor to form a first data set, performing regional analysis to obtain a flow velocity deviation value, evaluating heat exchange abnormality, positioning an abnormal position, and generating an abnormal region distribution map; a dynamic parameter adjustment scheme is calculated in combination with a heat exchange efficiency target, a first adjustment instruction set is generated, a second flow rate data set is obtained after execution, and the matching degree is evaluated through a fuzzy control algorithm; if the preset standard is not met, a second adjusting instruction set is generated in combination with working condition requirements, and finally an operation state report is output. The method has the following effects that the flow velocity distribution in the spiral wound tube type heat exchanger is accurately controlled, the problems of local overheating and uneven heat exchange are effectively solved, the heat exchange efficiency is improved, the purpose of balancing energy consumption is achieved, and stable operation of the system is guaranteed.

This utility model provides a pressure-resistant and flame-retardant PE hollow-wall spiral wound pipe, belonging to the technical field of hollow-wall spiral wound pipes. The pressure-resistant and flame-retardant PE hollow-wall spiral wound pipe provided by this utility model features a reinforcing tube with reinforcing ribs spirally wound on its outer circumference. Pressure-resistant filler is filled into the reinforcing ribs, improving the overall rigidity and pressure resistance of the spiral wound pipe, making it less prone to deformation and damage under external pressure. Simultaneously, a plastic spring is provided between the reinforcing tube and the spiral wound pipe body, providing internal support to the reinforcing tube and enhancing its ring stiffness and axial stiffness. Due to the plastic spring and the spirally wound reinforcing ribs on the outer circumference of the reinforcing tube, stress concentration is reduced, resulting in excellent bending resistance and preventing breakage of the spiral wound pipe. Furthermore, a flame-retardant and heat-insulating layer and a corrosion-resistant layer are provided on the outer circumference of the reinforcing tube, improving the flame retardancy and corrosion resistance of the spiral wound pipe.

This utility model relates to the field of spiral wound tube technology, specifically a multi-layer composite spiral wound tube structure, including a tube body with a supporting mechanism. The supporting mechanism includes an inner annular component fixedly connected to the outer wall of the tube body. Several inner annular components are arranged in an array. An outer protective tube is fixedly connected to the side of the inner annular component away from the tube body. Several arc-shaped tubes are arranged in an array on the outer wall of the outer protective tube. An outer annular groove is provided between the arc-shaped tubes and the outer protective tube. The cavity formed by the inner annular component, the outer protective tube, and the tube body is provided with an inner annular groove. A through groove is formed on the inner annular component. This utility model, through the reinforcing rib structure formed by the inner annular component and the outer protective tube, and the arc-shaped tubes dispersing external pressure, achieves a point-line-surface mechanical linkage, effectively improving the overall stability and deformation resistance of the tube body, enhancing its load-bearing capacity, and extending its service life.

A mixing machine used in hollow structure wall spiral winding pipe production equipment comprises a supporting frame, a mixing barrel installed on the supporting frame, a stirring shaft rotationally installed in the mixing barrel and a driving mechanism installed on one side of the supporting frame, the mixing barrel is transversely arranged to form a U-shaped groove structure with a top opening, materials can be poured into the mixing barrel from the top opening, and the mixing barrel is arranged in the U-shaped groove structure. The stirring shaft is transversely arranged in the material mixing barrel, the stirring shaft is driven by the driving mechanism to rotate, the multiple stirring rods extending in the radial direction are arranged on the stirring shaft, the stirring plates are arranged at the extending tail ends of the stirring rods, and materials in the material mixing barrel can be fully stirred through the transversely-arranged material mixing barrel and the multiple stirring rods; and when the stirring shaft rotates, the distance between the stirring plate and the bottom surface of the material mixing barrel does not exceed 3cm, so that even if the material is layered at the bottom, the stirring plate can stir the material, and the condition that the material is stacked at the bottom and cannot be stirred is avoided.

A crossbow includes a frame, first and second limbs, first and second cams, a drawstring, and first and second power cables. The frame includes a first side and a second side. The frame defines a projectile axis. The first limb is coupled to the first side and the second limb coupled to the second side. The first cam is coupled to the first side and configured to rotate about a first cam axis that is substantially parallel to the projectile axis. The second cam is coupled to the second side and configured to rotate about a second cam axis that is substantially parallel to the projectile axis. The drawstring is engaged with the first cam and the second cam. The first power cable is engaged with the first cam and the first limb. The second power cable engaged with the second cam and the second limb.

The utility model belongs to the technical field of machining, particularly relates to a ring bending device for a metal spiral wound gasket circular ring, and aims to solve the problems that manual size measurement is troublesome and welding is uneven in the background technology, the ring bending device comprises a bottom frame, a top frame is welded to the outer wall of the top of the bottom frame, and a side plate is welded to the outer wall of the top of the top frame. And the outer wall of one side of the side plate is fixedly connected with a guide rod. According to the utility model, along with continuous winding of the soft material, the size of the whole circular ring is continuously increased to contact with the pulley, the pulley is controlled to be close to the side plate, and the outer diameter of the circular ring can be accurately grasped by monitoring the distance of the calibration plate in real time through the photoelectric sensor, so that the size of the circular ring is quickly and effectively ensured to meet the standard; the laser welding head can uniformly weld the end part of the soft material along with downward pushing of the laser welding head by the cylinder and under the cooperation that the electric rotating chuck drives the circular ring to rotate, so that the position of a welding spot can be accurately grasped, and the welding uniformity is ensured.

The utility model relates to the technical field of winding pipes, in particular to an HDPE (high-density polyethylene) reinforced hollow winding pipe which comprises an outer layer and an inner layer, the inner wall of the outer layer is adhered to a high-strength adhesive, the inner wall of the high-strength adhesive is fixedly connected with a high-strength laminated steel wire mesh, and the outer wall of the high-strength laminated steel wire mesh is attached to the inner layer. The lower portion of the high-strength adhesive is fixedly connected with the inner layer, and a reinforcing mechanism is machined on the outer wall of the outer layer. Under the condition that the thicknesses of the outer layer and the inner layer are not changed, cavities in the spiral strips are extruded, deformed and rebounded, iron reinforcing wires in the fixing strips buffer impact force, direct contact between external force and the outer layer is reduced, and a high-strength laminated steel wire mesh is additionally arranged in a high-strength adhesive; the pulling force of the high-strength laminated steel wire mesh on the outer layer and the inner layer is enhanced, the situation that the outer layer and the inner layer are torn and damaged is reduced, and the overall using strength and the using environment are improved.

The pin type winding mechanism comprises a winding wheel and a top wheel which are oppositely arranged, the winding wheel can actively rotate, and a metal belt is wound on the winding wheel to form the winding gasket; a contact pin is arranged on the wheel face of the winding wheel, a connecting hole is formed in one end of the metal belt, and when the winding wheel rotates, the metal belt is rolled through insertion matching of the contact pin and the connecting hole. An inserting hole is formed in the wheel face of the winding wheel, and the inserting needle is telescopically arranged in the inserting hole. An elastic piece is arranged between the pin and the jack; under the elastic effect of the elastic piece, the pin tends to extend out of the jack. And when the contact pin retracts into the jack, the elastic piece is compressed. An adjusting sliding groove is formed in the side contour of the winding wheel and communicated with the inserting hole, and an adjusting pin is connected to one side of the inserting needle and correspondingly arranged in the adjusting sliding groove. According to the utility model, the connection mode of the metal belt and the winding wheel is improved, so that labor can be saved.

A cartridge filter includes a feedwater inlet, a first outlet and a second outlet, a tube arranged at the center of the cartridge filter, an interior volume of the tube being in fluid communication with the first outlet, and a spiral wound filter assembly extending radially outward from the central tube and including a prefilter, a reverse osmosis filter, and a postfilter. The prefilter is located radially outward from the reverse osmosis filter and the postfilter.

The utility model relates to the technical field of pipeline repairing, in particular to a pipeline cleaning device for repairing a pipeline through a trenchless spiral winding method. The device comprises a cleaning mechanism, pushing discs, a supporting advancing mechanism and a water inlet pipe which are sequentially arranged from front to back, the supporting advancing mechanism is used for being supported on the inner wall of a pipeline and driving the water inlet pipe to advance, and the pushing discs are arranged at the front end of the supporting advancing mechanism at intervals through connecting structures and used for pushing impurities on the inner wall of the pipeline to move forwards. The cleaning mechanism comprises a water spraying pipe and a cleaning brush which are arranged at the front end of the pushing disc, the water spraying pipe communicates with the water inlet pipe and is used for spraying water to the inner wall of the pipeline, and the periphery of the cleaning brush is used for being attached to the inner wall of the pipeline to brush the inner wall of the pipeline. The supporting advancing mechanism is used for driving the water inlet pipe to advance in the length direction of the pipeline, the cleaning mechanism is used for improving the impurity cleaning effect, the pushing disc is used for pushing impurities to move forwards, impurity accumulation is avoided, the cleaning process is prevented from being hindered, and the pipeline cleaning quality is guaranteed.

This invention discloses a BWFRP braided spiral wound power conduit, relating to the field of power cable protection conduit technology. It aims to solve problems such as significant decrease in tensile strength of existing BWFRP power conduits in humid and hot environments, insufficient interlayer bonding strength in multi-layer structures, difficulty in balancing ring stiffness and wall thickness, high material cost, inconvenient construction, and insufficient long-term reliability. The conduit includes a pipe body with a three-layer composite structure: an inner resin-rich layer, an outer weather-resistant and anti-aging layer, and an intermediate reinforcing layer accounting for 80%-90% of the wall thickness. The intermediate reinforcing layer includes an axial braided layer and a circumferential spiral wound layer; the axial braided layer is a ±55° bidirectional braided glass fiber cloth layer. This invention, through a composite structure of braiding and multi-angle alternating winding, and an interlayer hot-melt transition layer, significantly improves the axial and circumferential mechanical properties of the conduit, enhances interlayer bonding strength, improves strength retention after humid and hot aging, and optimizes the matching relationship between wall thickness and stiffness, achieving a balance between high strength and lightweight.

The utility model discloses a convenient-to-install one-piece roll type separation membrane component, including shell, central tube and membrane roll, the both ends of shell are equipped with the end cover that closely connects into one piece, the end cover includes cover plate and ring, the cover plate is fixed inside the ring, the ring includes the first ring and the second ring that are arranged on both sides of the cover plate, the first ring is sleeved outside the shell, the second ring is sleeved outside the shell, and the membrane roll is sleeved outside the central tube. The cover plate is provided with a water producing port and a water inlet and outlet port, the cover plate is provided with a water inlet and outlet pipe head communicated with the water inlet and outlet port, the outlet end of the water inlet and outlet pipe head is arranged on the outer side wall of the second ring, the surface, close to the shell, of the cover plate is provided with a flow dividing channel, and the second ring is provided with a plurality of U-shaped clamping grooves; according to the utility model, the stability and the sealing performance of the whole structure are improved, the assembly steps are reduced, the production efficiency is improved, the cost is reduced, the installation is convenient, the interference problem of the water producing pipe and the water inlet and outlet pipe is avoided, the installation is more flexible, the installation convenience is improved, the loading capacity is improved, and the application range of the product is expanded.

The utility model belongs to the technical field of winding reinforced structure wall A-type pipes, and particularly relates to an MUHDPE winding reinforced structure wall A-type pipe which comprises pipe bodies, lantern rings are fixedly arranged on the outer sides of the two ends of the pipe bodies, and a first semicircular steel sleeve shell and a second semicircular steel sleeve shell are arranged at the butt joint positions of the adjacent pipe bodies in a vertically sleeved mode. The first semicircular steel sleeve shell and the second semicircular steel sleeve shell are welded. The first semicircular steel sleeve shell and the second semicircular steel sleeve shell are connected to the outer side of the butt joint end of the pipe body in a sleeving mode, the first semicircular steel sleeve shell and the second semicircular steel sleeve shell are high in strength, excellent in extrusion resistance and capable of comprehensively wrapping and reinforcing the end of the pipe body, the end of the pipe body is not prone to deformation, and the butt joint position of the pipe body is not prone to deformation. The two-layer sealing effect is provided through the water retaining ring and the lantern ring, water is difficult to leak to the outer sides of the first semicircular steel sleeve shell and the second semicircular steel sleeve shell through the water retaining ring and the lantern ring, and therefore the sealing effect of the pipe body butt joint position is greatly improved.

Stabilized surfactant-based membranes and methods of manufacture thereof. Membranes comprising a stabilized surfactant mesostructure on a porous support may be used for various separations, including reverse osmosis and forward osmosis. The membranes are stabilized after evaporation of solvents; in some embodiments no removal of the surfactant is required. The surfactant solution may or may not comprise a hydrophilic compound such as an acid or base. The surface of the porous support is preferably modified prior to formation of the stabilized surfactant mesostructure. The membrane is sufficiently stable to be utilized in commercial separations devices such as spiral wound modules. Also a stabilized surfactant mesostructure coating for a porous material and filters made therefrom. The coating can simultaneously improve both the permeability and the filtration characteristics of the porous material.

This invention relates to the field of spiral wound molding technology and discloses an HDPE pipe spiral wound structural wall pipe spiral wound molding equipment, including a base, a vertical plate mounted on the top of the base, a pulley on the top of the vertical plate, a mandrel splicing assembly on the top of the pulley, and a cooling and shaping assembly on the outer wall of the mandrel splicing assembly. By employing high-frequency mechanical vibration of piezoelectric ceramic water spray, and transmitting the vibration to the cooling water interface, the surface tension of water molecules is broken, allowing atmospheric pressure cooling water to be directly atomized into uniform micro-droplets without the need for a high-pressure pump. The atomized droplets can be aligned with the adsorption holes and directionally sprayed onto the pipe surface to achieve efficient heat exchange, reducing energy consumption and making the droplet distribution more uniform. Utilizing the existing shaped adsorption holes as the spray channel for subsequent atomization cooling, vacuum adsorption + water-cooled spraying is achieved, simplifying the structure while ensuring cooling uniformity and eliminating cooling dead zones caused by nozzle arrangement deviations in traditional spray devices.

The invention provides a metal spiral wound gasket production device and process, and relates to the technical field of metal spiral wound gasket production, the metal spiral wound gasket production device comprises a placing frame and a core fixing mechanism arranged on the placing frame; a pushing air cylinder is fixedly connected to the containing frame, an abutting spring is fixedly connected to an output shaft of the pushing air cylinder, a sliding block is fixedly connected to the end, away from the abutting air cylinder, of the abutting spring, the sliding block is slidably connected with the containing frame, and an abutting rotating wheel is rotationally connected to the sliding block. And the abutting rotating wheel is used for abutting against the side wall of the positioning ring, an abutting block is slidably connected to the sliding block, an abutting wheel is rotatably connected to the abutting block, and the abutting wheel is used for abutting against the metal belt after winding. Looseness of the winding layer can be reduced, and installation of the outer ring can be assisted.

This utility model discloses a winding device for producing metal spiral wound gaskets, including a bracket, two circular blocks passing through the middle of the bracket, a first support roller on one side of the bracket, the circular blocks being inserted into the first support roller, a second support roller detachably connected to one side of the bracket, and a third support roller on the other side of the bracket. A drive motor fixedly connected to one end of the third support roller is fixedly connected to the bracket, and two first support shafts are fixedly connected to the front of the bracket. This utility model has the advantage of tension adjustment.

The utility model relates to the technical field of metal spiral wound gaskets, in particular to a metal spiral wound gasket structure which comprises a stainless steel inner ring, a compression-resistant mechanism is arranged on the outer side of the stainless steel inner ring, the compression-resistant mechanism comprises connecting grooves formed in the upper side and the lower side of the stainless steel inner ring, and clamping inner rings are clamped in the connecting grooves. A special-shaped outer ring is fixedly connected to the side, away from the stainless steel inner ring, of the clamping inner ring, two sets of supporting plates are arranged in the clamping inner ring, the side, away from the stainless steel inner ring, of the special-shaped outer ring is in a concave shape, and an extrusion block is fixedly connected to the inner side wall of the special-shaped outer ring. According to the utility model, the stainless steel inner ring is matched with the compression-resistant mechanism, and the flexible graphite ring on the outer side of the V-shaped inner stainless steel ring is utilized to increase the overall deformation adaptability, so that the shape of the stainless steel inner ring can be flexibly adjusted when the stainless steel inner ring is stressed or deformed; and the supporting elastic cotton on the two sides extrudes the supporting plate to upwards abut against the elastic gasket and the extension ring so as to improve the elasticity of the edge.

This invention discloses a solid-wall spiral wound tube extrusion production equipment, belonging to the technical field of spiral wound tube forming equipment. It includes an injection molding machine body with a forming assembly mounted on it; a drive assembly includes a first gear rotatably mounted on the forming assembly and a second gear meshing with the first gear, the second gear being driven by a second motor; a feeding assembly includes an electric cylinder and a guide tube slidably connected to the first gear, a connecting plate mounted on the output end of the electric cylinder being rotatably connected to the guide tube, an electric gripper mounted on the guide tube, a driven roller rotatably mounted on one arm of the electric gripper, and a clamping rod fixedly mounted on the other arm. The driven roller of this invention, through its dual function of clamping and pressing, achieves seamless connection of molten material guidance, stable winding, and interface adhesion during the spiral wound tube production process; the top roller and the roller body work together to effectively prevent reverse slippage of the extruded material during winding, ensuring the continuity and stability of the winding process.

The invention relates to the technical field of storage racks, in particular to an FEP winding pipe which comprises a winding pipe body and further comprises a buffering assembly, the buffering assembly comprises an arch rubber frame and a buffering cylinder, the arch rubber frame is connected with the winding pipe body, and the buffering cylinder is connected with the arch rubber frame and the winding pipe body. When the winding pipe main body is subjected to pressure or impact force, the impact force can be transmitted to the circular-arch rubber frame, so that the circular-arch rubber frame is compressed and deformed to buffer the impact force, and meanwhile, in the compression deformation of the circular-arch rubber frame, a buffer cylinder between the circular-arch rubber frame and the winding pipe main body can be extruded; and through the stability of the circular arch structure of the circular arch rubber frame and the deformation buffering of the buffering cylinder, the cable in the winding pipe main body is subjected to anti-impact protection, and the cable is prevented from being damaged due to impact force.

This utility model discloses an anti-oxidation spiral wound pipe, comprising a spiral wound pipe body, with a protective strip spirally wound around the outer side of the spiral wound pipe body. Multiple vertical ribs are clamped onto the outer side of the protective strip. Each vertical rib has an open C-shaped structure, and the open structures of adjacent vertical ribs are arranged opposite each other. The protective strip, from the inside out, includes an adhesive layer, a buffer layer, a base layer, and an anti-oxidation layer. Through this structure, after the protective strip is wound around the outside of the spiral wound pipe, the vertical ribs are clamped onto the spiral wound pipe. The protective strip protects the spiral wound pipe and reduces contact with the external environment. The vertical ribs provide support, increasing the ring stiffness of the pipe, enabling it to better resist external pressure and maintain pipeline stability during underground installation. The overall protective effect of the protective strip improves the corrosion resistance and oxidation resistance of the spiral wound pipe.

The application discloses a fatigue life analysis method of a spiral wound heat exchanger based on tube bundle equivalence, and belongs to the technical field of life analysis of spiral wound heat exchangers. In order to solve the problems of high calculation cost and long simulation period of existing full tube bundle refined modeling, the application extracts target heat exchanger parameters to establish an analysis parameter set, uses a mixing law to equivalently convert a single hollow heat exchange tube into a solid tube, combines a Mori-Tanaka equivalent method to calculate macroscopic elastic constants of the wound tube bundle, and obtains an equivalent wound tube bundle model. After assembling the equivalent tube bundle model with the rest of the component models, finite element simulation is carried out, stress response of a dangerous point is extracted, Goodman correction formula is used to convert alternating dynamic load into a symmetric cyclic stress amplitude, and S-N curve is combined to obtain a permissible fatigue cycle number. The application is suitable for fatigue life evaluation of various spiral wound heat exchangers.

A coiled tube heat exchanger using a deformable support system and a method for manufacturing a tube bundle for the coiled tube heat exchanger. The coiled tube heat exchanger includes: a mandrel; a first pipe layer formed by winding one or more pipes around the mandrel; and a plurality of supports and spacers circumferentially arranged on an outer surface of the first pipe layer in an alternating pattern. A second tube layer is formed by winding one or more tubes around the mandrel, whereby the second tube layer contacts opposite sides of the support. A deformation force is applied to the second tube layer in a direction normal to the outer surface of each support, which causes the one or more tubes forming the second tube layer to deform the outer support surface of each support.

A crossbow includes a frame, first and second limbs, first and second cams, a drawstring, and first and second power cables. The frame includes a first side and a second side. The frame defines a projectile axis. The first limb is coupled to the first side and the second limb coupled to the second side. The first cam is coupled to the first side and configured to rotate about a first cam axis that is substantially parallel to the projectile axis. The second cam is coupled to the second side and configured to rotate about a second cam axis that is substantially parallel to the projectile axis. The drawstring is engaged with the first cam and the second cam. The first power cable is engaged with the first cam and the first limb. The second power cable engaged with the second cam and the second limb.

Printed spacer film elements offer the unique advantage of applying any pattern on the film surface to act as a supply spacer material. This is in contrast to conventional supply spacer web materials that are uniform in thickness and density across the web. More open supply spaces can be used but can also result in higher stress concentrations and where the spacer material is in contact with the opposing film leaf. This patent presents the concept for reducing damage on the film leaf by increasing the printed pattern concentration near the center tube where stress concentration is the greatest, orienting the film leaf to minimize damage from slippage during crimping before crimping, moving the fold away from the first feature to minimize leakage at the insertion point.

The utility model discloses a high-temperature-resistant metal spiral-wound gasket and relates to the technical field of spiral-wound gaskets, the high-temperature-resistant metal spiral-wound gasket comprises a sealing ring, a fixed inner ring is arranged on the inner side wall of the sealing ring, a fixed outer ring is arranged on the outer side wall of the sealing ring, the sealing ring comprises a metal temperature-resistant belt and a temperature-resistant filling belt, and the metal belt and the filling belt are wound to form a ring shape. First fixing parts are arranged on the two sides of the sealing ring, the first fixing parts are connected with the metal belt and the filling belt, and second fixing parts connected with the first fixing parts are arranged on the fixing inner ring and the fixing outer ring. The fixing inner ring and the fixing outer ring are arranged on the inner side and the outer side of the sealing ring, the sealing ring is supported and fixed, and the situation that the sealing ring is scattered and fails due to the fact that the metal belt and the filling belt which surround each other in the sealing ring are scattered is prevented; the metal belt and the filling belt are prevented from being damaged by high temperature, and the high-temperature-resistant effect of the metal spiral-wound gasket is improved.

The present invention belongs to the field of high-concentration brine treatment, and discloses a high-concentration brine concentration reduction system and method. The system includes a pretreatment unit, a SWRO spiral wound reverse osmosis unit, and at least one stage of tubular membrane concentration reduction unit. The technology of the present invention breaks through the traditional concept of continuously increasing the operating pressure to pursue a higher concentration limit, and replaces one-step concentration with gradient concentration, which is a high-concentration brine high-fold concentration technology with low cost and low energy consumption.

This utility model relates to the technical field of plastic spiral wound pipes, and in particular to a double-peak reinforced spiral wound drainage pipe. The spiral wound drainage pipe is formed by winding a plastic-steel pipe body, and molten material is provided at the overlap between any two adjacent plastic-steel pipe bodies. First peaks are symmetrically arranged at both ends of the outer surface of the plastic-steel pipe body, and a second peak is arranged in the middle of the outer surface of the plastic-steel pipe body. Multiple steel wires are co-extruded inside the side of the plastic-steel pipe body. The first peaks at both ends of the outer surface of the plastic-steel pipe body form large trough areas, and the second peak is located within these large trough areas. A reinforcing rib is provided inside the second peak, and an inner arc-shaped groove is provided at the top of the second peak. This utility model can shorten the span between the two first peaks, enhance the strength of the trough areas, and the reinforcing rib and the inner arc-shaped groove form a Y-shaped support structure, which can better provide support and has stronger compressive strength.

The utility model discloses a plant anti-bite device, relates to the technical field of plant planting protection, and mainly aims to protect a planted tree and automatically adjust the size of the plant anti-bite device along with the growth of the tree. According to the main technical scheme, the plant bite prevention device comprises an elastic protection plate, a plurality of rows of first magnets and at least one row of second magnets. The elastic protection plate is spirally wound in a plane, one end of the elastic protection plate located on the spiral winding inner ring is a first end, and one end of the elastic protection plate located on the spiral winding outer ring is a second end. The first magnets are sequentially arranged on the outer side face of the first end of the elastic protection plate. At least one column of second magnets are positioned on the inner side surface of the second end of the elastic protection plate; and the second magnet is correspondingly contacted with the first magnet.