US20180100269A1

US20180100269A1 - Method for fabricating steel wire cable comprising zinc- aluminium alloy plating

Info

Publication number: US20180100269A1
Application number: US15/836,898
Authority: US
Inventors: Jun Zhao; Shiwei NING; Huajuan Xue; Zhubing Zhou; Qiong Wu; Qiang Qiang; Kebin HUANG; Xiaoxiong ZHU; Weihong SHU; Jin Wang; Zhongmei LIANG; Pengcheng ZHAI
Original assignee: Jiangsu Fasten Steel Cable Co Ltd
Current assignee: Jiangsu Fasten Steel Cable Co Ltd
Priority date: 2016-04-13
Filing date: 2017-12-10
Publication date: 2018-04-12
Also published as: CN105862592A; CN105862592B; EP3348712A4; EP3348712A1; WO2017177518A1; EP3348712B1

Abstract

A method for fabricating a steel wire cable having a Zn—Al alloy plating, the method including: arranging steel wires according to an arrangement rule at a cross section of the steel wire cable; controlling a length of the overall cable by a length of a central standard wire; twisting a bunch of the steel wires comprising a zinc-aluminum alloy plating with a torsion angle of between 2° and 4°; wrapping the steel wire bunch with a polyester wrapping bandage and covering a resulting product with a double-layered protective polyethylene sheath; anchoring the two ends of the steel wire cable by anchors using fillers; and coiling the finished-product of the steel wire cables.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of International Patent Application No. PCT/CN2016/083894 with an international filing date of May 30, 2016, designating the United States, now pending, and further claims foreign priority benefits to Chinese Patent Application No. 201610229109.1 filed Apr. 13, 2016. The contents of all of the aforementioned applications, including any intervening amendments thereto, are incorporated herein by reference. Inquiries from the public to applicants or assignees concerning this document or the related applications should be directed to: Matthias Scholl P. C., Attn.: Dr. Matthias Scholl Esq., 245 First Street, 18th Floor, Cambridge, Mass. 02142.

BACKGROUND OF THE INVENTION

Field of the Invention

The invention relates to a method for fabricating a steel wire cable comprising a Zinc-Aluminum (Zn—Al) alloy plating.

Description of the Related Art

A cable-stayed bridge includes one or more towers, from which cables provide support for the bridge deck. In recent years, to accelerate the development of coastal economy, the construction of large-span cable-stayed bridges has become increasingly urgent. However, conventional galvanized steel wire cables are not weather resistant, and especially, are not durable under marine climates.

SUMMARY OF THE INVENTION

In view of the above-described problems, it is one objective of the invention to provide a method for fabricating a steel wire cable comprising a Zn—Al alloy plating. The length of the overall cable is controlled by the length of a central standard wire; a bunch of the steel wires comprising a zinc-aluminum alloy plating are twisted with a torsion angle of between 2° and 4°; the steel wire bunch is then wrapped with a polyester wrapping bandage and covered with a double-layered protective polyethylene sheath by using double-cavity co-extrusion process for one-step formation, and the outer surface of the polyethylene sheath is provided with embossments for rain-wind induced vibration resistance; the two ends of the steel wire cable are fixed by anchors using fillers, coiled, and stored. And the coils of the steel wire cables are then transported to and respectively laid on a construction field.
To achieve the above objective, in accordance with one embodiment of the invention, there is provided a method for fabricating a steel wire cable comprising a Zn—Al alloy plating. The method comprises the following steps:
1) Fabricating a Steel Wire Comprising a Zinc-Aluminum Alloy Plating
The steel wire comprising the zinc-aluminum alloy plating is adopted because the zinc-aluminum alloy plating possesses much stronger anti-corrosive property, principle of which is as follows: a) as aluminum has very active chemical property, a dense layer of alumina is formed on a surface of the steel wire after hot dip of aluminum, and therefore the surface of the steel wire is easily inactivated to form a protective layer in corrosive environment. In a corrosive medium, a zinc-enriched surface layer, functioning as a positive electrode, is firstly eroded, the aluminum content continuously increases to make the alumina content increase, thus making the plating layer possessing stronger capability of preventing external toxic substances. In the meanwhile, the addition of the aluminum also inhibits the formation of a zinc-aluminum transitional layer which has weaker anti-corrosion performance and loosen tissue, thus being helpful for improving the overall anti-corrosion performance of the plating layer. b) When the zinc-aluminum alloy plating is destructed and the steel is exposed, the plating functions as a positive electrode of an iron-zinc aluminum battery and is dissolved, and a steel substrate is therefore protected. A corrosion potential of the zinc-aluminum alloy is slightly lower than a pure zinc layer and is approximately −0.87, but the corrosion current of the zinc-aluminum alloy is only 1/5 of the hot dipped pure zinc. Under the protection of sacrificing the positive electrode, the consumption time of the zinc-aluminum alloy plating of the same amount is five folds of that of the hot dipped zinc layer. Thus, the zinc-aluminum alloy plating is able to provide much longer sacrificial protection time and possesses better endurance. The zinc-aluminum alloy plating includes two types, Zn95Al5 5 having an aluminum content of between 4.2 and 7.2 wt. %, and Zn90Al10 having the aluminum content of between 9.2 and 12.2 wt. %. A plating weight is equal to or larger than 300 g/m². A homogeneity indicator of the plating satisfies a time of copper sulfate of equal to or larger than 4 with each time lasting 60 s.
2) Fabricating a Steel Wire having a Standard Length
As each layer of steel wires in the stay cable exists with a certain torsion angle, it is unable to directly control the length of the steel wire cable by using the outer layers of steel wires. Only the central wire of the stay cable always remains straight without being twisted during the whole fabrication process, therefore, the central wire is utilized as the standard wire to control the overall length of the steel wire cable.
The length of the standard wire is determined by baseline measurement, and specific operation includes: applying a certain tension force to two ends of a steel wire to straighten the steel wire a performing stress correction and temperature correction using the following equation:
L=L ₀×[(1+F/EA)+α(T−20)]
in which, L represents a length (m) of the steel wire in a stressed state, L₀represents a designed length, m, of the steel wire in an unstressed state, F represents a tensioning force, N, E represents an elastic module, MPa, of the steel wire, and fabrication of the standard wire adopts a measured value, A represents an area of a cross section, m², of the steel wire, and fabrication of the standard wire adopts the measured value, a represents an expansion coefficient of the steel wire, and T represents a temperature, ° C., of the environment.
A steel wire having a standard length is prepared. Certain markers for cutting are made at two ends of the steel wire. Thereafter, the steel wire having the standard length is utilized as a reference, and the overall length of the steel wire cable is controlled by a transfer method. By using the above measurements, the length error of the stay cable can be greatly reduced. The fabrication precision of the standard wire exceeds 1/30000, and the fabrication precision of the finished product of the steel wire cable is improved from the China's national standard of 1/5000 to 1/20000.
3) Twisting a Steel Wire Bunch
The steel wire cable is formed by multiple layers of steel wires. When relaxing the steel wires, the standard wire is positioned at a center position of a cross section of the steel wire cable.
A steel wire bunch is twisted to the left with a torsion angle of between 2° and 4°. The twisted steel wire bunch is wrapped to the right by a wrapping bandage to yield a naked steel wire cable as a semi-product. As lengths of the multiple layers of the steel wires exist with differences, a relaxed length L^/of other layers of steel wires surrounding the standard wire considering the length of the standard wire is calculated according to the following equation:
L ₀ =L ^/×cos α+K
in which, α represents the torsion angle ranging from 2° to 4°; K represents a fabrication allowance, m, which is selected according to specifications and operations; L^/represents the relaxed length, m, of other layers of the steel wires surrounding the standard wire; and Lo represents the length, m, of the standard wire at the center position;
An outer dimeter of the steel wire bunch, i.e., the naked steel wire cable, after being twisted is measured. Because the cross section of the steel wire bunch is in a shape of hexagon or hexagon with missing angles, a circumscribed circle of the selected cross section of the steel wire bunch is directly the diameter of the naked steel wire cable.
The wrapping bandage is preferably a bandage made from a polyester fiber. The wrapping bandage has a width of between 40 and 60 mm and a tensile strength of equal to or high than 500 N/25 mm².
4) Extruding
A double-layered protective polyethylene is prepared outside the naked steel wire cable, in which, the double-layered protective polyethylene has a density of between 0.942 and 0.978 g/cm³, environmental stress crack resistance property of ≥5000 F₀/h, and a melt index of ≤0.45 g/10 min. Specific operation is as follows:
Before extruding, a die aperture of an extruder and an extrusion velocity are preset according to an outer diameter of the naked steel wire cable and thicknesses of two layers of polyethylene. The double-cavity co-extrusion for one-step formation is adopted. The two layers of the polyethylene plastics simultaneously cover the naked steel wire cable during the requirements of anti-corrosion. According to the requirement of resistance of the rain-wind induced vibration, after the extrusion, an outer surface of the double-layered protective polyethylene is provided with helical lines or embossments. When reaching the effect of the steel wire cable in effectively inhibiting the rain-wind induced vibration, a drag coefficient is equal to or smaller than 0.8.
5) Accurate Cutting
Original cutting positions of the steel wire cable are determined, the double-layered protective polyethylene is locally stripped, and the markers for cutting at two ends of the standard wire at the center position of the steel wire cable are found. Then, the steel wire cable is cut by using a non-liquid cutting machine and end faces of the steel wire cable are ensured perpendicular to an axis of the steel wire cable. The double-layered protective polyethylene is stripped according to a preset length to expose the steel wires, during which, the plating of the steel wires is prevented from being destructed.
6) Casting Anchor
The anchor is a main connecting structure to transmit a tension of the steel wire cable to a tower and a girder. The steel wire cable adopts anchor structures including a nut-screwing type anchor, an anchor plate gap adjusting type anchor, or a fork-ear pin joint type anchor at two ends. The anchor is performed with hot galvanizing or paint coating for corrosion resistance. A thickness of the hot galvanizing is equal to or larger than 90 μm, and a thickness of the paint coating is determined according to specifications and design requirements of a steel structure. The types of the structures of the anchor is as follows:
a) Nut-Screwing Type Anchor
The nut screwing type anchor comprises: an anchor cup, a screw nut, an anchor plate, and a sealing assembly of a connecting cylinder. Such steel wire cable utilizes the end face of the nut to support the pressure and to transmit the load. The nut and the anchor cup are in rotary joint via a trapezoidal thread having high strength to realize the continuous adjustment of the length of the steel wire cable. The anchor cup is provided with tensional inner threads. In installation of the steel wire cable on the construction site, an installation force is applied on the steel wire cable by drawing the anchor. The anchor plate primarily functions in dispersing the steel wires, steel wire holes are distributed on the anchor plate, and the steel wires pass through corresponding steel wire holes and are headed. An external cone boss can be tightly attached to an internal conical cavity.
b) End Face-Supporting Type Anchor
The end face-supporting type anchor comprises: an anchor cup, an anchor plate, and a sealing assembly of a connecting cylinder. End faces of such steel wire cable are directly supported on anchor plate, and different gap adjusting plates are utilized to regulate the length of the steel wire cable. The gas adjusting plates have different thicknesses to satisfy the requirement of the construction site. The anchor cup is provided with tensional inner threads. In installation of the steel wire cable on the construction site, an installation force is applied on the steel wire cable by drawing the anchor. Such kind of anchor does not necessitate nuts, and the anchor cup is not provided with external threads. The anchor plate functions in dispersing the steel wires, the steel wire holes are distributed on the anchor plate, and the steel wires pass through corresponding steel wire holes and are headed. An external cone boss can be tightly attached to an internal conical cavity.
c) Fork-Ear Pin Joint Type Anchor at One End and Nut-Screwing Type Anchor at the Other End
The fork-ear pin joint type anchor comprises: a fork ear, a pin shaft, an anchor cup, a nut, and a sealing assembly of a connecting cylinder. One end of such steel wire cable is connected to the steel structure of the tower or the girder via the fork ear and the pin shaft, and the other end of the steel wire cable adopts an end face of a nut to bear pressure and to transmit the load, thus realizing the continuous adjustment of the length of the steel wire cable. the anchor cup is provided with tensional inner threads. In installation of the steel wire cable on the construction site, an installation force is applied on the steel wire cable by drawing the anchor. The anchor plate functions in dispersing the steel wires, the steel wire holes are distributed on the anchor plate, and the steel wires pass through corresponding steel wire holes and are headed. An external cone boss can be tightly attached to an internal conical cavity.
The sealing assembly of the connecting cylinder in the above three structures all adopts the new type of cable end sealing technology, in which, an outer part of the connecting cylinder is firstly sealed by a sealing cover, and an inner wall of the connecting cylinder in the vicinity of a port is sealed again by an elastic sealing ring and a sealing press ring. The two sealing measurements finally realizes the sealing of the two ends of the steel wire cable, that is, the sealing between the anchors and the interfaces of the polyethylene steel wire cable. The sealing assembly has stronger strength, thus being difficult to be destructed, much longer service life, and much endurable sealing structure.
The sealing structure at the ends of the steel wire cable is a reliable mechanical sealing structure, configured to prevent the corrosion resulting from the water penetration into the PE cable. In the meanwhile, the sealing structure, as a substitute of a heat shrink sleeve, is utilized for sealing, thus overcoming the problem of damage of the heat shrink sleeve.
The technical solution to solve the above described technical problem is as follows: an endurable sealing structure at an end of the steel wire cable. The sealing structure fits together with the connecting cylinder of the anchor and comprises: the elastic sealing ring, a sealing press ring, and a sealing cover. The sealing press ring is disposed in the port of the connecting cylinder and an outer end of the sealing press ring is exposed outside the connecting cylinder. A press surface is formed on the inner wall of the connecting cylinder relative to the inner end face of the sealing press ring. The elastic sealing ring is disposed between the inner end face of the sealing press ring and the press surface. Under the press of the press surface, the elastic sealing ring is deformed and attached to the outer wall of the steel wire cable. The sealing cover is disposed on a front end of the connecting cylinder and possesses a Harvard structure. A front part of the sealing cover contacts and fits with the outer wall of the steel wire cable and a corresponding contact surface is provided with a sealing ring. A rear part of the sealing cover contacts and fits with the sealing press ring or the connecting cylinder and a corresponding contact surface is provided with a sealing strip.
The casting of the anchor is carried out by chill casting of heading anchor or by hot casting of anchor, operations of which are as follows:
A. Chill Casting of Heading Anchor
a. Ends of the steel wires are fixed in anchor cups on a casting platform, oil stains and rusts are removed from portions of the steel wires inside the anchor cups, and inner walls of the anchor cups are synchronously washed.
b. The ends of the steel wires are uniformly dispersed corresponding to holes of anchor plates, and each steel wire is headed by using a heading machine. Heading dimensions are as follows: heading diameter ≥1.4 D, heading height ≥1.0 D, and D represents a diameter of the steel wires.
c. A chilled filler comprising steel balls, a stone dust, an epoxy resin, a curing agent, di-n-butyl, and a diluent is provided and uniformly mixed. A mixture of the chilled filler is poured into the anchor cups while vibrating by using a vibration pump to fully fill gaps among the anchor cup and steel wires with the mixture of the chilled filler.
d. A compression strength of the casting body of the chilled filler is ≥147 MPa.
B. Hot Casting of Anchor
The hot casting anchor adopts a zinc alloy for casting, and a zinc-copper alloy and a zinc-copper-aluminum alloy are the common two alloys.
The zinc-copper alloy comprises 98±0.2 wt. % of zinc and 2±0.2 wt. % of copper, and the zinc-copper-aluminum alloy comprises 4-7 wt. % of aluminum, 1-2 wt. % of copper, and 91-95 wt. % of zinc. The casting is performed as follows:
a. Ends of the steel wires are perpendicularly fixed in anchor cups on the casting platform, steel wires comprising a zinc-aluminum alloy plating are dispersed inside the anchor cups in the form of concentric circles. Oil stains and rusts are then removed from surfaces of the steel wires, and the inner walls of the anchor cups are simultaneously washed.
b. The center of the steel wire cable is kept coincide with centers of the anchor cups, and steel wires are prevented from contacting the anchor cups.
c. Bottom openings of the anchor cups are sealed to prevent the alloy from leaking via the bottom openings. The anchor cups are preheated.
d. The zinc-copper alloy or the zinc-copper-aluminum alloy is poured into the anchor cups for one-step casting while avoiding any vibration or disruption.
7) Performing Tension Detection or Top Pressure Detection
The tension detection or the top pressure detection are important means to detect the quality of the steel wire cable. According to fillers for the casting of the anchor, the tension detection is performed on the steel wire cable with chilled-casted anchor or the top pressure detection is performed on the steel wire cable with hot-casted anchor before leaving a plant, which is specifically as follows:
For the steel wire cable with the chilled-casted anchor, the steel wire cable is stretched by an overstretching force which is set to be between 1.1 and 1.5 folds of a designed tension of the steel wire cable and satisfies that a retraction value of a casting body inside the anchor cup after stretching is equal to or less than 6 mm.
The overstretching force is then unloaded to be 20% of the original overstretching force or to be the designed tension of the steel wire cable after the stretching. A length of the steel wire cable is measured at a constant temperature in the dark, and a stressless length of the steel wire cable is calculated at a reference temperature according to the following equation:
$L_{CO} = \frac{L_{CP}}{1 + \frac{P_{20}}{EA} + α (t - t_{0})}$
in which, L_C0represents the stressless length, m, of the steel wire cable at the reference temperature; L_CPrepresents a length, m, of the steel wire cable loaded with a tension force of P₂₀; P₂₀represents 20% of the overstretching force, N; A represents a nominal area, mm², of the steel wire bunch of the steel wire cable; E represents an elastic modulus, MPa; α represents a coefficient of linear expansion of a stay cable which is equal to 0.000012/° C.; t represents the constant temperature, ° C., when measuring a length of the stay cable; and t₀represents a designed reference temperature, ° C., of the stay cable.
For the steel wire cable with hot-casted anchor, a top pressure is applied to the steel wire cable. The top pressure is 1.25 folds of the designed tension of the steel wire cable and satisfies that a retraction value of the casting body inside the anchor cup after the top pressure detection is equal to or less than 6 mm.
8) Coiling
The steel wire cable is coiled by a coil frame. Before the coiling, an outer surface of the steel wire cable is packed, and layers of the steel wire cables are successively coiled by using the coil frame. An inner diameter of a resulting coil is equal to or larger than 20 folds of an outer diameter of the steel wire cable and is equal to or larger than 1.6 m.
9) Storing
Finished product of the steel wire cable adopts indoor storage or outdoor storage. When the indoor storage is adopted, an oilcloth is used to cover the steel wire cable. A storage site is equipped with ventilation and fire-proof facilities to ensure the quality and the safety of the stored steel wire cables.
Advantages of the method for fabricating the steel wire cable according to embodiments of the invention are summarized as follows: the steel wires are arranged according to the arrangement rule at the cross section of the steel wire cable. The length of the overall cable is controlled by the length of the central standard wire. The bunch of the steel wires comprising the zinc-aluminum alloy plating are twisted with the torsion angle of between 2° and 4°. The steel wire bunch is then wrapped with the polyester wrapping bandage and covered with the double-layered protective polyethylene sheath by using double-cavity co-extrusion process for one-step formation, and the outer surface of the polyethylene sheath is provided with embossments for rain-wind induced vibration resistance. The two ends of the steel wire cable are fixed by anchors using fillers, coiled, and stored. And the coils of the steel wire cables are then transported to and respectively laid on the construction field. The fabrication of the steel wire cable of the invention is not restricted by the construction site, and hardly affected by the climate factors. And the management of the industrialized production is easily controllable. All these satisfy the use requirements of long length, high accuracy, and endurance of the stay cable for the large-span bridge used in the marine environment.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described hereinbelow with reference to the accompanying drawings, in which:

FIG. 1 is a structure diagram illustrating two nut-screwing type anchors at two ends of a steel wire cable in accordance with one embodiment of the invention;

FIG. 2 is a structure diagram illustrating two anchor plate gap adjusting type anchors at two ends of a steel wire cable in accordance with one embodiment of the invention;

FIG. 3 is a structure diagram illustrating a fork-ear pin joint type anchor at one end of a steel wire cable and a nut-screwing type anchor at the other end of the steel wire cable in accordance with one embodiment of the invention; and

FIG. 4 is a side view of FIG. 3.

In the drawings, the following numbers are utilized: 1. Anchor plate; 2. Anchor cup; 3. Sealing assembly of a connecting cylinder; 4. Steel wire cable; 5. Sealing structure at an end of a steel wire cable; 6. Nut; 7. Gap adjusting plate; 8. Pin shaft; and 9. Fork ear.

DETAILED DESCRIPTION OF THE EMBODIMENTS

For further illustrating the invention, experiments detailing a method for fabricating a steel wire cable comprising a Zn—Al alloy plating are described below. It should be noted that the following examples are intended to describe and not to limit the invention.
In the method of the invention, steel wires comprising a zinc-aluminum alloy plating are twisted together to form a naked steel wire cable, an outer layer of the naked steel wire cable is covered by a double-layered protective polyethylene by extrusion. Two ends of a resulting steel wire cable are then anchored by casting, coiled, transported to the construction site and laid respectively.
1) fabricating a steel wire comprising a zinc-aluminum alloy plating
The steel wire comprising the zinc-aluminum alloy plating is adopted because the zinc-aluminum alloy plating possesses much stronger anti-corrosive property. The zinc-aluminum alloy plating includes two types, Zn95Al5 5 having an aluminum content of between 4.2 and 7.2 wt. %, and Zn90Al10 having the aluminum content of between 9.2 and 12.2 wt. %. A plating weight is equal to or larger than 300 g/m².
2) fabricating a Steel Wire having a Standard Length
As each layer of steel wires in the stay cable exists with a certain torsion angle, it is unable to directly control the length of the steel wire cable by using the outer layers of steel wires. Only the central wire of the stay cable always remains straight without being twisted during the whole fabrication process, therefore, the central wire is utilized as the standard wire to control the overall length of the steel wire cable.
The length of the standard wire is determined by baseline measurement, and specific operation includes: applying a certain tension force to two ends of a steel wire to straighten the steel wire a performing stress correction and temperature correction using the following equation:
L=L ₀×[(1+F/EA)+α(T−20)]
in which, L represents a length (m) of the steel wire in a stressed state, L₀represents a designed length, m, of the steel wire in an unstressed state, F represents a tensioning force, N, E represents an elastic module, MPa, of the steel wire, and fabrication of the standard wire adopts a measured value, A represents an area of a cross section, m², of the steel wire, and fabrication of the standard wire adopts the measured value, a represents an expansion coefficient of the steel wire, and T represents a temperature, ° C., of the environment.
A steel wire having a standard length is prepared. Certain markers for cutting are made at two ends of the steel wire. Thereafter, the steel wire having the standard length is utilized as a reference, and the overall length of the steel wire cable is controlled by a transfer method.
3) Twisting a Steel Wire Bunch
The steel wire cable is formed by multiple layers of steel wires. When relaxing the steel wires, the standard wire is positioned at a center position of a cross section of the steel wire cable.
A steel wire bunch is twisted to the left with a torsion angle of between 2° and 4°. The twisted steel wire bunch is wrapped to the right by a wrapping bandage to yield a naked steel wire cable as a semi-product. As lengths of the multiple layers of the steel wires exist with differences, a relaxed length L^/of other layers of steel wires surrounding the standard wire considering the length of the standard wire is calculated according to the following equation:
L ₀ =L ^/×cos α+K
in which, α represents the torsion angle ranging from 2° to 4°; K represents a fabrication allowance, m, which is selected according to specifications and operations; L^/represents the relaxed length, m, of other layers of the steel wires surrounding the standard wire; and L₀represents the length, m, of the standard wire at the center position;
An outer dimeter of the steel wire bunch, i.e., the naked steel wire cable, after being twisted is measured. Because the cross section of the steel wire bunch is in a shape of hexagon, a circumscribed circle of the selected cross section of the steel wire bunch is directly the diameter of the naked steel wire cable.
4) Extruding
A double-layered protective polyethylene is prepared outside the naked steel wire cable. before extruding, a die aperture of an extruder and an extrusion velocity are preset according to an outer diameter of the naked steel wire cable and thicknesses of two layers of polyethylene. The double-cavity co-extrusion for one-step formation is adopted. The two layers of the polyethylene plastics simultaneously cover the naked steel wire cable during the requirements of anti-corrosion.
According to the requirement of resistance of the rain-wind induced vibration, after the extrusion, an outer surface of the double-layered protective polyethylene is provided with helical lines or embossments. When reaching the effect of the steel wire cable in effectively inhibiting the rain-wind induced vibration, a drag coefficient is equal to or smaller than 0.8.
5) Accurate Cutting
Original cutting positions of the steel wire cable are determined, the double-layered protective polyethylene is locally stripped, and the markers for cutting at two ends of the standard wire at the center position of the steel wire cable are found. Then, the steel wire cable is cut by using a non-liquid cutting machine and end faces of the steel wire cable are ensured perpendicular to an axis of the steel wire cable. The double-layered protective polyethylene is stripped according to a preset length to expose the steel wires, during which, the plating of the steel wires is prevented from being destructed.
6) Casting Anchor
The anchor is a main connecting structure to transmit a tension of the steel wire cable to a tower and a girder. Anchor structures of the steel wire cable are as follows: two nut-screwing type anchors disposed at two ends of the steel wire cable, as shown in FIG. 1, two anchor plate gap adjusting type anchors at two ends of the steel wire cable, as shown in FIG. 2, and a fork-ear pin joint type anchor at one end of the steel wire cable and a nut-screwing type anchor at the other end of the steel wire cable, as shown in FIGS. 3-4.
a) Nut-Screwing Type Anchor
The nut screwing type anchor comprises: an anchor cup, a screw nut, an anchor plate, and a sealing assembly of a connecting cylinder. Such steel wire cable utilizes the end face of the nut to support the pressure and to transmit the load. The nut and the anchor cup are in rotary joint via a trapezoidal thread having high strength to realize the continuous adjustment of the length of the steel wire cable. The anchor cup is provided with tensional inner threads. In installation of the steel wire cable on the construction site, an installation force is applied on the steel wire cable by drawing the anchor. The anchor plate primarily functions in dispersing the steel wires, steel wire holes are distributed on the anchor plate, and the steel wires pass through corresponding steel wire holes and are headed. An external cone boss can be tightly attached to an internal conical cavity.
b) End Face-Supporting Type Anchor
The end face-supporting type anchor comprises: an anchor cup, an anchor plate, and a sealing assembly of a connecting cylinder. End faces of such steel wire cable are directly supported on anchor plate, and different gap adjusting plates are utilized to regulate the length of the steel wire cable. The gas adjusting plates have different thicknesses to satisfy the requirement of the construction site. The anchor cup is provided with tensional inner threads. In installation of the steel wire cable on the construction site, an installation force is applied on the steel wire cable by drawing the anchor. Such kind of anchor does not necessitate nuts, and the anchor cup is not provided with external threads. The anchor plate functions in dispersing the steel wires, the steel wire holes are distributed on the anchor plate, and the steel wires pass through corresponding steel wire holes and are headed. An external cone boss can be tightly attached to an internal conical cavity.
c) Fork-Ear Pin Joint Type Anchor at One End and Nut-Screwing Type Anchor at the Other End
The fork-ear pin joint type anchor comprises: a fork ear, a pin shaft, an anchor cup, a nut, and a sealing assembly of a connecting cylinder. One end of such steel wire cable is connected to the steel structure of the tower or the girder via the fork ear and the pin shaft, and the other end of the steel wire cable adopts an end face of a nut to bear pressure and to transmit the load, thus realizing the continuous adjustment of the length of the steel wire cable. the anchor cup is provided with tensional inner threads. In installation of the steel wire cable on the construction site, an installation force is applied on the steel wire cable by drawing the anchor. The anchor plate functions in dispersing the steel wires, the steel wire holes are distributed on the anchor plate, and the steel wires pass through corresponding steel wire holes and are headed. An external cone boss can be tightly attached to an internal conical cavity.
The sealing assembly of the connecting cylinder in the above three structures all adopts the new type of cable end sealing technology, in which, an outer part of the connecting cylinder is firstly sealed by a sealing cover, and an inner wall of the connecting cylinder in the vicinity of a port is sealed again by an elastic sealing ring and a sealing press ring. The two sealing measurements finally realizes the sealing of the two ends of the steel wire cable, that is, the sealing between the anchors and the interfaces of the polyethylene steel wire cable. The sealing assembly has stronger strength, thus being difficult to be destructed, much longer service life, and much endurable sealing structure.
The sealing structure at the ends of the steel wire cable is a reliable mechanical sealing structure, configured to prevent the corrosion resulting from the water penetration into the PE cable. In the meanwhile, the sealing structure, as a substitute of a heat shrink sleeve, is utilized for sealing, thus overcoming the problem of damage of the heat shrink sleeve.
The technical solution to solve the above described technical problem is as follows: an endurable sealing structure at an end of the steel wire cable. The sealing structure fits together with the connecting cylinder of the anchor and comprises: the elastic sealing ring, a sealing press ring, and a sealing cover. The sealing press ring is disposed in the port of the connecting cylinder and an outer end of the sealing press ring is exposed outside the connecting cylinder. A press surface is formed on the inner wall of the connecting cylinder relative to the inner end face of the sealing press ring. The elastic sealing ring is disposed between the inner end face of the sealing press ring and the press surface. Under the press of the press surface, the elastic sealing ring is deformed and attached to the outer wall of the steel wire cable. The sealing cover is disposed on a front end of the connecting cylinder and possesses a Harvard structure. A front part of the sealing cover contacts and fits with the outer wall of the steel wire cable and a corresponding contact surface is provided with a sealing ring. A rear part of the sealing cover contacts and fits with the sealing press ring or the connecting cylinder and a corresponding contact surface is provided with a sealing strip.
The anchor is performed with hot galvanizing or paint coating for corrosion resistance. A thickness of the hot galvanizing is equal to or larger than 90 um, and a thickness of the paint coating is determined according to specifications and design requirements of a steel structure.
The casting of the anchor is carried out by chill casting of heading anchor or by hot casting of anchor, operations of which are as follows:
A. Chill Casting of Heading Anchor
a. Ends of the steel wires are fixed in anchor cups on a casting platform, oil stains and rusts are removed from portions of the steel wires inside the anchor cups, and inner walls of the anchor cups are synchronously washed.
b. The ends of the steel wires are uniformly dispersed corresponding to holes of anchor plates, and each steel wire is headed by using a heading machine. Heading dimensions are as follows: heading diameter ≥1.4 D, heading height ≥1.0 D, and D represents a diameter of the steel wires.
c. A chilled filler comprising steel balls, a stone dust, an epoxy resin, a curing agent, di-n-butyl, and a diluent is provided and uniformly mixed. A mixture of the chilled filler is poured into the anchor cups while vibrating by using a vibration pump to fully fill gaps among the anchor cup and steel wires with the mixture of the chilled filler.
B. Hot Casting of Anchor
The hot casting anchor adopts a zinc alloy for casting, and a zinc-copper alloy and a zinc-copper-aluminum alloy are the common two alloys.
The zinc-copper alloy comprises 98±0.2 wt. % of zinc and 2±0.2 wt. % of copper, and the zinc-copper-aluminum alloy comprises 4-7 wt. % of aluminum, 1-2 wt. % of copper, and 91-95 wt. % of zinc. The casting is performed as follows:
a. Ends of the steel wires are perpendicularly fixed in anchor cups on the casting platform, steel wires comprising a zinc-aluminum alloy plating are dispersed inside the anchor cups in the form of concentric circles. Oil stains and rusts are then removed from surfaces of the steel wires, and the inner walls of the anchor cups are simultaneously washed.
b. The center of the steel wire cable is kept coincide with centers of the anchor cups, and steel wires are prevented from contacting the anchor cups.
c. Bottom openings of the anchor cups are sealed to prevent the alloy from leaking via the bottom openings. The anchor cups are preheated.
d. The zinc-copper alloy or the zinc-copper-aluminum alloy is poured into the anchor cups for one-step casting while avoiding any vibration or disruption.
7) Performing Tension Detection or Top Pressure Detection
The tension detection or the top pressure detection are important means to detect the quality of the steel wire cable. According to fillers for the casting of the anchor, the tension detection is performed on the steel wire cable with chilled-casted anchor or the top pressure detection is performed on the steel wire cable with hot-casted anchor before leaving a plant, which is specifically as follows:
For the steel wire cable with the chilled-casted anchor, the steel wire cable is stretched by an overstretching force which is set to be between 1.1 and 1.5 folds of a designed tension of the steel wire cable and satisfies that a retraction value of a casting body inside the anchor cup after stretching is equal to or less than 6 mm.
The overstretching force is then unloaded to be 20% of the original overstretching force or to be the designed tension of the steel wire cable after the stretching. A length of the steel wire cable is measured at a constant temperature in the dark, and a stressless length of the steel wire cable is calculated at a reference temperature according to the following equation:
$L_{CO} = \frac{L_{CP}}{1 + \frac{P_{20}}{EA} + α (t - t_{0})}$
in which, L_C0represents the stressless length, m, of the steel wire cable at the reference temperature; L_CPrepresents a length, m, of the steel wire cable loaded with a tension force of P₂₀; P₂₀represents 20% of the overstretching force, N; A represents a nominal area, mm², of the steel wire bunch of the steel wire cable; E represents an elastic modulus, MPa; α represents a coefficient of linear expansion of a stay cable which is equal to 0.000012/° C.; t represents the constant temperature, ° C., when measuring a length of the stay cable; and to represents a designed reference temperature, ° C., of the stay cable.
An error of the stressless length of the steel wire cable at the reference temperature satisfies the following requirements:
when L_C0<100 m, the error is less than or equal to 10 mm; and
when L_C0>100 m, the error is less than or equal to L_C0/20000+5 mm.
For the steel wire cable with hot-casted anchor, a top pressure is applied to the steel wire cable. The top pressure is 1.25 folds of the designed tension of the steel wire cable and satisfies that a retraction value of the casting body inside the anchor cup after the top pressure detection is equal to or less than 6 mm.
8) Coiling
The steel wire cable is coiled by a coil frame. Before the coiling, an outer surface of the steel wire cable is packed, and layers of the steel wire cables are successively coiled by using the coil frame. An inner diameter of a resulting coil is equal to or larger than 20 folds of an outer diameter of the steel wire cable and is equal to or larger than 1.6 m.
9) Storing
Finished product of the steel wire cable adopts indoor storage or outdoor storage. When the indoor storage is adopted, an oilcloth is used to cover the steel wire cable. A storage site is equipped with ventilation and fire-proof facilities to ensure the quality and the safety of the stored steel wire cables.
Unless otherwise indicated, the numerical ranges involved in the invention include the end values. While particular embodiments of the invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from the invention in its broader aspects, and therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of the invention.

Claims

The invention claimed is:

1. A method for fabricating a steel wire cable, comprising:

1) preparing steel wires comprising a zinc-aluminum alloy plating, wherein the zinc-aluminum alloy plating has an aluminum content of between 4.2 and 7.2 wt. % or of between 9.2 and 12.2 wt. %, and a weight of the zinc-aluminum alloy plating is equal to or larger than 300 g/m²;

2) selecting a steel wire, which is to be positioned at a center position of a cross section of the steel wire cable, as a standard wire, applying a certain tension force to two ends of the steel wire to straighten the steel wire and performing stress correction and temperature correction to prepare a steel wire having a standard length; making certain markers at two ends of the steel wire; taking the steel wire having the standard length as a reference, and controlling an overall length of the steel wire cable;

3) relaxing the steel wires, positioning the standard wire at the center position of the cross section of the steel wire cable comprising a plurality of layers of steel wires; twisting the steel wires to the left with a torsion angle of between 2° and 4° to yield a steel wire bunch; wrapping the steel wire bunch to the right by a wrapping bandage to yield a naked steel wire cable as a semi-product; and calculating a relaxed length L^/of other layers of steel wires surrounding the standard wire considering the length of the standard wire and a torsion rate according to the following equation:

L ₀ =L ^/×cos α+K

in which, α represents the torsion angle ranging from 2° to 4°; K represents a fabrication allowance, m, which is selected according to specifications and operations; L_/represents the relaxed length, m, of other layers of the steel wires surrounding the standard wire; and L₀represents the length, m, of the standard wire at the center position;

4) preparing a double-layered protective polyethylene outside the naked steel wire cable, wherein the double-layered protective polyethylene has a density of between 0.942 and 0.978 g/cm³, environmental stress crack resistance property of ≥5000 F₀/h, and a melt index of ≤0.45 g/10 min; before extruding, presetting a die aperture of an extruder and an extrusion velocity according to an outer diameter of the naked steel wire cable and thicknesses of two layers of polyethylene; wherein the die aperture of the extruder is provided with two layers of discharge channel, and the two layers of polyethylene simultaneously cover the naked steel wire cable during the extrusion;

5) determining original cutting positions of the steel wire cable, locally stripping the double-layered protective polyethylene, finding the markers for cutting at two ends of the standard wire at the center position of the steel wire cable; cutting the steel wire cable by using a non-liquid cutting machine and ensuring end faces of the steel wire cable perpendicular to an axis of the steel wire cable; stripping the double-layered protective polyethylene according to a preset length to expose the steel wires;

6) providing an anchor functioning as a main connecting structure to transmit a tension of the steel wire cable to a tower and a girder; performing hot galvanizing or paint coating on the anchor for corrosion resistance, wherein a thickness of the hot galvanizing is equal to or larger than 90 μm, and a thickness of the paint coating is determined according to specifications and design requirements of a steel structure; and casting the anchor by chill casting of heading anchor or by hot casting of anchor, operations of which are as follows:

A. chill casting of the heading anchor comprising:

a. fixing ends of the steel wires in anchor cups on a casting platform, removing oil stains and rusts from portions of the steel wires inside the anchor cups, and synchronously washing inner walls of the anchor cups;

b. uniformly dispersing the ends of the steel wires corresponding to holes of anchor plates, and heading each steel wire by using a heading machine, wherein heading dimensions are as follows: heading diameter ≥1.4 D, heading height ≥1.0 D, and D represents a diameter of the steel wires; and

c. providing and uniformly mixing a chilled filler comprising steel balls, a stone dust, an epoxy resin, a curing agent, di-n-butyl, and a diluent; pouring a mixture of the chilled filler into the anchor cups while vibrating by using a vibration pump to fully fill gaps among the anchor cup and steel wires with the mixture of the chilled filler;

B. hot casting of anchor comprising:

providing a zinc-copper alloy comprising 98±0.2 wt. % of zinc and 2±0.2 wt. % of copper, or a zinc-copper-aluminum alloy comprising 4-7 wt. % of aluminum, 1-2 wt. % of copper, and 91-95 wt. % of zinc; and performing casting as follows:

a. perpendicularly fixing ends of the steel wires in anchor cups on the casting platform, dispersing steel wires comprising a zinc-aluminum alloy plating inside the anchor cups in the form of concentric circles, removing oil stains and rusts from surfaces of the steel wires, and simultaneously washing the inner walls of the anchor cups;

b. keeping the center of the steel wire cable coincide with centers of the anchor cups and preventing steel wires from contacting the anchor cups;

c. sealing bottom openings of the anchor cups to prevent the alloy from leaking via the bottom openings; and preheating the anchor cups; and

d. pouring the zinc-copper alloy or the zinc-copper-aluminum alloy into the anchor cups for one-step casting while avoiding any vibration or disruption;

7) according to fillers for the casting of the anchor, performing tension detection on the steel wire cable with chilled-casted anchor or performing top pressure detection on the steel wire cable with hot-casted anchor before leaving a plant, which comprises:

for the steel wire cable with the chilled-casted anchor, stretching the steel wire cable by an overstretching force which is set to be between 1.1 and 1.5 folds of a designed tension of the steel wire cable and satisfies that a retraction value of a casting body inside the anchor cup after stretching is equal to or less than 6 mm;

unloading the overstretching force to be 20% of the original overstretching force or to be the designed tension of the steel wire cable after the stretching; measuring a length of the steel wire cable at a constant temperature in the dark, and calculating a stressless length of the steel wire cable at a reference temperature according to the following equation:

L_{CO} = \frac{L_{CP}}{1 + \frac{P_{20}}{EA} + α (t - t_{0})}

in which, L_C0represents the stressless length, m, of the steel wire cable at the reference temperature; L_CPrepresents a length, m, of the steel wire cable loaded with a tension force of P₂₀; P₂₀represents 20% of the overstretching force, N; A represents a nominal area, mm², of the steel wire bunch of the steel wire cable; E represents an elastic modulus, MPa; α represents a coefficient of linear expansion of a stay cable which is equal to 0.000012/° C.; t represents the constant temperature, ° C., when measuring a length of the stay cable; and to represents a designed reference temperature, ° C., of the stay cable; and

for the steel wire cable with hot-casted anchor, applying, to the steel wire cable, a top pressure which is 1.25 folds of the designed tension of the steel wire cable and satisfies that a retraction value of the casting body inside the anchor cup after the top pressure detection is equal to or less than 6 mm; and

8) packing an outer surface of the steel wire cable, coiling layers of the steel wire cables successively by using a coil frame, wherein an inner diameter of a resulting coil is equal to or larger than 20 folds of an outer diameter of the steel wire cable and is equal to or larger than 1.6 m.

2. The method of claim 1, wherein when determining the length of the standard wire in 2), stress correction and temperature correction are carried out according to the following equation:

L=L ₀×[(1+F/EA)+α(T−20)]

in which, L represents a length (m) of the steel wire in a stressed state, L₀represents a designed length, m, of the steel wire in an unstressed state, F represents a tensioning force, N, E represents an elastic module, MPa, of the steel wire, and fabrication of the standard wire adopts a measured value, A represents an area of a cross section, m², of the steel wire, and fabrication of the standard wire adopts the measured value, a represents an expansion coefficient of the steel wire, and T represents a temperature of the environment.

3. The method of claim 1, wherein in extrusion process in 4), a magnetic field is arranged above the steel wire cable to make the steel wire cable in a suspension state; after the extrusion process, the double-layered protective polyethylene and the naked steel wire cable are concentrically arranged.

4. The method of claim 1, wherein an outer surface of the double-layered protective polyethylene is provided with helical lines or embossments, and a drag coefficient is equal to or smaller than 0.8.

5. The method of claim 1, wherein structures of the anchors in 6) adopt a nut-screwing type anchor, an anchor plate gap adjusting type anchor, or a fork-ear pin joint type anchor at two ends of the steel wire cable.

6. The method of claim 1, wherein in 7), an error of the stressless length of the steel wire cable at the reference temperature satisfies the following requirements:

when L_C0≤100 m, the error is less than or equal to 10 mm; and

when L_C0>100 m, the error is less than or equal to L_C0/20000+5 mm.

7. The method of claim 1, wherein the wrapping bandage is a bandage made from a polyester fiber; the wrapping bandage has a width of between 40 and 60 mm and a tensile strength of equal to or high than 500 N/25 mm².