CN115301757B

CN115301757B - Automatic coating process for insulated wire and cable

Info

Publication number: CN115301757B
Application number: CN202210814344.0A
Authority: CN
Inventors: 吴国华; 杨洁素; 林建武
Original assignee: Guangdong Jinyangguang Cable Industry Co ltd
Current assignee: Guangdong Jinyangguang Cable Industry Co ltd
Priority date: 2022-07-12
Filing date: 2022-07-12
Publication date: 2024-05-14
Anticipated expiration: 2042-07-12
Also published as: CN115301757A

Abstract

The invention discloses an automatic coating process of an insulated wire and a cable, which belongs to the technical field of wires and cables, and comprises the steps of firstly, respectively preprocessing a pre-prepared steel wire raw material and a pre-prepared zinc rod raw material, wherein the preprocessing comprises straightening, online cleaning and surface blow-drying; then, carrying out medium-frequency induction heating on the steel wire under the protection of nitrogen with the purity of 99%, and then cladding and combining the steel wire and the zinc rod in an extruder; then, cooling the zinc-coated steel wire obtained by coating; and after the end is cut and the tail is removed, carrying out on-line detection on the zinc-coated steel wire, continuously extruding and coating the insulating sheath on the zinc-coated steel wire, and finally preparing an insulating wire and cable product. The invention solves the technical problems of easy breakage of the core wire, loose welding seam, eccentricity and the like of the zinc-coated steel wire in the prior art.

Description

Automatic coating process for insulated wire and cable

Technical Field

The invention relates to the technical field of wires and cables, in particular to an automatic coating process of an insulated wire and cable.

Background

As a bimetal composite material, the zinc-coated steel wire has the high strength of steel wires and the good conductive and corrosion-resistant performances of zinc alloy. The zinc-coated steel wire has been widely applied to the fields of oil pipelines, urban pipe networks and the like, and particularly has outstanding application to the zinc-coated steel wire in corrosive environments. At present, the zinc-coated steel wire is mainly galvanized on the steel wire by adopting an electrochemical method, and the process has the defects of low production efficiency, serious pollution and the like. Based on this, chinese patent CN109500129B discloses a method for manufacturing multipurpose zinc-coated steel; which comprises the following steps: the method comprises the steps of carrying out chemical-free environment-friendly treatment on the surface of a steel wire, carrying out surface cleaning treatment on the steel wire by a belt sander, enabling the cleaned steel wire to enter a continuous coating machine for extrusion simultaneously with two zinc bars after being heated by an intermediate frequency furnace to obtain zinc-coated steel, controlling the heating temperature of the intermediate frequency furnace to be 200-250 ℃, assembling an extrusion die and a guide die by the coating machine according to product requirements, controlling the size of a nose groove assembled by the die to be 3-6mm according to the diameter of the steel wire, controlling the temperature of a die cavity to be 150-250 ℃, controlling the rotating speed of an extrusion wheel to be 3-7 r, and controlling the extrusion speed to be 70-120 m/min; and carrying out composite metal drawing on the coated zinc-coated steel bus. The manufacturing method of the multipurpose zinc-coated steel has the advantages of no chemical pollution and flexible production.

However, the above disclosed method for manufacturing the multipurpose zinc-coated steel has the technical problems that the core wire is easy to be broken, the welding seam is not tight, and the core wire is eccentric. Specifically, the continuous extrusion coating test is carried out on the zinc-coated steel according to the manufacturing method of the zinc-coated steel, and the research result shows that: the quality and the productivity of the product are determined by the zinc deformation temperature, the rotating speed of the extrusion wheel, the preheating temperature of the steel core, the speed of the steel core, the tension of the steel core and other technological parameters in the extrusion compounding process; only by purposefully controlling the parameters, the smooth production of the zinc-coated steel wire can be ensured, and the qualification rate of the zinc-coated steel wire product can be improved.

Disclosure of Invention

Based on the above, it is necessary to provide an automatic coating process for insulated wires and cables, aiming at the technical problems of easy breakage of the core wire, loose weld joint, eccentricity and the like of the zinc-coated steel wire in the prior art.

An automatic coating process for insulated wires and cables comprises the following steps:

S1: pre-preparing a steel wire raw material and a zinc rod raw material, and respectively pre-treating the steel wire raw material and the zinc rod raw material; the pretreatment comprises straightening, online cleaning and surface blow-drying;

S2: preheating the steel wire to 360-420 ℃ by using an intermediate frequency induction heater; the steel wire is heated and protected by adopting a nitrogen conveying device, the purity of nitrogen is not lower than 99%, and the flow value of nitrogen is controlled to be 1.2m ²/h;

S3: respectively dragging the steel wire and the zinc rod into a continuous extrusion compounding machine to finish the compounding process; the temperature of the initial mould shoe is not lower than 320 ℃, the automatic high-speed state temperature is controlled between 250 ℃ and 300 ℃, the temperature of the extrusion wheel is not higher than 270 ℃, and the temperature of cooling water is not higher than 50 ℃; the extrusion wheel speed is controlled between 3 and 6r.min ^-1, the wire line speed is controlled between 1.08 and 2.16 m.min ^-1, and the compound speed is controlled between 1.7 and 4.9 m.min ^-1;

s4: the zinc-coated steel wire after extrusion compounding is cooled by using a cooling water tank; the front half part of the cooling water tank is a circulating water tank, and the rear half part of the cooling water tank is a static water tank; a blowing device is arranged at the outlet of the water tank to blow-dry the water on the zinc-coated steel wire;

S5: cutting the end and the tail of the cooled zinc-coated steel wire respectively, and keeping on-line detection; then, a tension wheel is used for dragging the zinc-coated steel wire at the rear of the cooling water tank, and the traction force range is 2000-5000N;

s6: taking up wires by adopting a gantry type wire taking-up and arranging machine, wherein the wire taking-up and arranging speed is more than 160m/min;

S7: coating the zinc-coated steel wire with an insulating sheath by using a continuous extruder; then, the sheath is treated by using a cross-linking irradiation process;

S8: and (5) after the finished product is inspected to be qualified, delivering the finished product to a warehouse.

Specifically, in step S1, the original structure of the steel wire is sorbite, and the disk weight of the steel wire is greater than 1 ton.

Specifically, in step S1, the online cleaning process of the steel wire or the zinc rod includes an alkali liquor cleaning tank, an acid liquor cleaning tank and a water rinsing tank; and the rinsing tank is provided with a vibration damping device for preventing vibration of the raw materials; and the outlets of the rinsing tanks are provided with blowing devices to blow the cleaned raw materials dry.

Specifically, the alkali liquor cleaning tank for the steel wire adopts 10% NaOH solution, the temperature is controlled between 38 ℃ and 42 ℃, and the pressure is 1.25MPa; the acid liquor cleaning tank adopts 10% H ₂SO₄ solution, the temperature is controlled at room temperature, and the pressure is controlled at 1.25MPa; the temperature of the water rinsing tank is controlled at room temperature, and the pressure is controlled at 0.30MPa.

Specifically, the alkali liquor cleaning tank of the zinc rod is 10% NaOH solution, the temperature is controlled between 38 ℃ and 42 ℃, and the pressure is 1.20MPa; the acid liquor cleaning tank is an 8% H ₂SO₄ solution, the temperature is controlled at room temperature, and the pressure is controlled at 0.30MPa; the temperature of the water rinsing tank is controlled at room temperature, and the pressure is controlled at 0.30MPa.

Specifically, in step S2, the intermediate frequency induction heater includes a silicon controlled rectifier, a tuning capacitor, and an inductor.

Specifically, the alternating current is changed into direct current through a silicon controlled rectifier group, and the direct current is converted into preset frequency through a tuning capacitor and an inductor.

Specifically, in step S3, the cooling water of the pinch roller is softened by a hard water softening device.

In summary, the automatic coating process of the insulated wire and the cable comprises the steps of respectively preprocessing the prepared steel wire raw material and the zinc rod raw material, wherein the preprocessing comprises straightening, online cleaning and surface blow-drying; then, carrying out medium-frequency induction heating on the steel wire under the protection of nitrogen with the purity of 99%, and then cladding and combining the steel wire and the zinc rod in an extruder; then, cooling the zinc-coated steel wire obtained by coating; and after the end is cut and the tail is removed, carrying out on-line detection on the zinc-coated steel wire, continuously extruding and coating the insulating sheath on the zinc-coated steel wire, and finally preparing an insulating wire and cable product. And by further refining the zinc deformation temperature, the rotating speed of the extrusion wheel, the steel wire preheating temperature, the steel wire speed, the tension of the steel wire and other technological parameters, the defects that the core wire is extruded and broken, the welding seam is not tight, eccentric and the like can be avoided in the extrusion process of the zinc-coated steel wire can be ensured by controlling the parameters. The reason that the core wire is extruded and broken is that the deformed length of the composite area is too large, the extrusion ratio is too large or the core wire is eccentric; the reason for the poor weld is mainly because the design of the shunt bridge is too wide; and the reason for the eccentricity is that the design of the die is not reasonable. Therefore, the automatic cladding process for the insulated wire and the cable solves the technical problems that a core wire of a zinc-clad steel wire in the prior art is easy to be crushed, a welding line is not tight, the eccentric and the like.

Drawings

FIG. 1 is a process flow diagram of an automatic insulated wire and cable coating process according to the present invention;

FIG. 2 is a diagram showing the configuration of a production line of an automatic coating process for insulated wires and cables according to the present invention;

Fig. 3 is a schematic diagram of a design of a composite mold for an automatic coating process of insulated wires and cables according to an embodiment of the present invention.

Detailed Description

In order that the above objects, features and advantages of the invention will be readily understood, a more particular description of the invention will be rendered by reference to the appended drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. The present invention may be embodied in many other forms than described herein and similarly modified by those skilled in the art without departing from the spirit of the invention, whereby the invention is not limited to the specific embodiments disclosed below.

In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the device or element being referred to must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the present invention.

Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present invention, the meaning of "plurality" means at least two, for example, two, three, etc., unless specifically defined otherwise.

In the present invention, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; either directly or indirectly, through intermediaries, or both, may be in communication with each other or in interaction with each other, unless expressly defined otherwise. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.

In the present invention, unless expressly stated or limited otherwise, a first feature "up" or "down" a second feature may be the first and second features in direct contact, or the first and second features in indirect contact via an intervening medium. Moreover, a first feature being "above," "over" and "on" a second feature may be a first feature being directly above or obliquely above the second feature, or simply indicating that the first feature is level higher than the second feature. The first feature being "under", "below" and "beneath" the second feature may be the first feature being directly under or obliquely below the second feature, or simply indicating that the first feature is less level than the second feature.

It will be understood that when an element is referred to as being "fixed" or "disposed" on another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and the like are used herein for illustrative purposes only and are not meant to be the only embodiment.

Referring to fig. 1 and fig. 2 together, fig. 1 is a process flow chart of an automatic coating process for insulated wires and cables according to the present invention; fig. 2 is a diagram of a production line configuration of an automatic coating process for insulated wires and cables according to the present invention. As shown in fig. 1, the automatic coating process of the insulated wire and the cable of the invention comprises the following steps:

Specifically, the aim of the raw material pretreatment process is to remove the surface pollution and oxide skin of the steel wire and the zinc rod so as to ensure that good combination is formed between the steel and the zinc in extrusion compounding. The raw material pretreatment process can be divided into a steel wire pretreatment system and a zinc rod wire rod pretreatment system. The zinc-coated steel wire blank after zinc coating can reach the size of a finished product only by multi-pass drawing, and an annealing process is not allowed in the process of processing the blank, so that the original structure of the steel wire is required to be sorbite, and the disc weight of the steel wire is preferably more than 1 ton. Because the production speed of the continuous extrusion composite process can reach more than 100m/min, if a small disc weight is used, the situation of frequent shutdown occurs, thereby affecting the economy of the cladding process; moreover, the welding strength of the steel wire can not meet the quality requirement of the finished product. In order to ensure that the steel wire and the zinc rod have better concentricity during cladding, the front tension paying-off is required to be carried out, namely a tension wheel is added in front of a paying-off machine; so as to ensure that the steel wire has higher flatness during cladding. In addition, the steel wire is often subjected to some degree of non-flatness after handling and paying-off, which is not allowed in a continuous extrusion compounding process. Therefore, the production line must be equipped with straightening equipment. The other function of straightening is that after the steel wire is repeatedly bent, the surface oxide skin is loose and easy to remove, which also provides a better preparation condition in the early process for the subsequent steel wire rust removal.

Further, a shot blasting method or a high-pressure vortex cleaning method may be used in the surface cleaning process of the steel wire. The shot blasting method is a process for bombarding a steel wire by using high-speed steel shots to enable oxide scales on the surface of the steel wire to fall off. The cleaning agent has the advantage of good online cleaning effect; in addition, after shot blasting treatment, the surface of the steel wire forms a micro pit, which is beneficial to increasing the biting area between steel and zinc, thereby being beneficial to improving the bonding strength between steel and zinc. However, the method has poor degreasing effect, and the shot blasting equipment has high investment cost and high maintenance cost. The high-pressure vortex cleaning method is a cleaning method integrating mechanical and chemical combined actions. The cleaning device consists of a high-pressure pump and a cleaning head forming high-pressure vortex. Under the action of high pressure, the chemical cleaning liquid forms high-speed and high-pressure vortex in the cleaning head, so that the steel wire is strongly vibrated, and collision friction is formed between the steel wire and the surface of the cleaning head, thereby playing a role in mechanical rust removal. On the other hand, the chemical rust removing liquid has better chemical decontamination effect, and meanwhile, mechanical vibration friction strengthens the chemical cleaning effect. The method has good decontamination effect, but has certain limit on the running speed of the steel wire, and the cleaning effect is easily influenced by the too high speed. Therefore, the method has better effect when being applied to off-line cleaning.

Further, the raw material zinc rod used in the continuous extrusion composite production line is generally a zinc rod wire rod with a wire diameter of 8-10 mm. The components of the zinc rod wire rod should meet the national standard of corresponding brands, but the following two quality requirements must be met: firstly, the surface of the zinc rod is as oil-free as possible. And the grease is often used as a process lubricant for domestic production of zinc rod wire rods, so that a large amount of greasy dirt is remained on the surface of the zinc rod. This presents difficulties for subsequent cleaning procedures. Secondly, the air content in the zinc tissue is low. The zinc rod wire rod production factory is required to have a purifying and degassing device in the zinc liquid casting process, otherwise, the higher air content and impurities in the zinc rod wire rod can also cause the problems of bubble generation, peeling and the like of products. In addition, since the zinc rod wire rods are supplied in rolls, there are bends of different degrees after unwinding, and thus it is necessary to add an on-line straightening device for the zinc rods. Furthermore, the continuous extrusion compounding process requires high surface cleanliness of raw materials, and therefore, the zinc rod must be cleaned on line. The method for online cleaning the zinc rod wire rod mainly comprises the following steps: a steel wire brush mechanical cleaning method, an ultrasonic water agent cleaning method, a rigid brush cleaning agent combined cleaning method, a high-pressure vortex cleaning method and a rigid brush-high-pressure vortex combined cleaning method. The above cleaning methods all have certain drawbacks, such as: in the wire brush mechanical cleaning method, the high-speed rotating wire brush directly acts on the surface of the zinc rod, so that oxide layers, dust and the like on the surface of the zinc rod are removed. However, the method has limited cleaning effect on greasy dirt and the like on the surface of the zinc rod. Therefore, the cleaning quality of the zinc rod is difficult to be ensured by singly using the method. Also for example: in the ultrasonic water agent cleaning method, the zinc rod passes through a cleaning box filled with chemical cleaning agent, and an ultrasonic vibrator is arranged on the outer wall of the cleaning box. The ultrasonic wave generated by the vibrator acts on the surface of the zinc rod through the cleaning liquid, so that the greasy dirt on the surface of the zinc rod is stripped under the chemical action of the cleaning liquid by ultrasonic vibration. However, the method has a good effect on removing only a small amount of dust and a small amount of thin oil agent because the action area and the intensity of the ultrasonic wave are limited.

Further, based on the foregoing, the cleaning of the zinc rod or wire is preferably performed on-line using a cypress top cleaner. The Bai Luobi top cleaning machine is a unique online cleaning system, and a group of hydraulic converters are utilized to clean zinc rods or steel wires under the action of low-corrosiveness chemical cleaning agents. Under the action of high pressure, the chemical cleaning liquid forms high-speed and high-pressure vortex in the cleaning head to cause strong vibration of the rod material, so that collision friction is formed between the rod material and the surface of the cleaning head, and the mechanical rust removal effect is further realized. On the other hand, the selected chemical rust removing liquid has better chemical decontamination effect, and simultaneously the mechanical vibration friction strengthens the effect of chemical cleaning, thereby the cleaning of the zinc rod or the steel wire can reach good cleaning degree. Specifically, in the on-line cleaning system of zinc bars or steel wires, each cleaning tank is provided with an inlet and an outlet, and air knives are arranged at the outlets of the 6 hydraulic converters to prevent the cleaning liquid from overflowing. Each end of each hydraulic converter cavity is provided with two tungsten carbide guide molds, the diameter of each tungsten carbide guide mold is slightly larger than that of the raw material to be cleaned, and hot cleaning liquid sprayed at high speed is injected from the side surface of each hydraulic converter cavity, so that strong vortex is formed around the raw material; and overflows by guiding the tungsten carbide mold. So that the raw materials are cleaned in the liquid sprayed at high speed and vortex; and passing through a tungsten carbide die and then a cleaning tank.

Specifically, an alkali liquor cleaning tank, an acid liquor cleaning tank and a water rinsing tank are respectively arranged in the system for cleaning the steel wire and the zinc rod; and, the rinsing tanks of the two cleaning systems are provided with vibration damping and resisting devices so as to prevent the vibration of the raw materials; and the outlets of the rinsing tanks are provided with blowing devices to blow the cleaned raw materials dry. Particularly, the specific proportion of the steel wire to the zinc rod cleaning liquid is different, wherein a 10% NaOH solution is selected as an alkali liquor cleaning tank of the zinc rod, the temperature is controlled between 38 ℃ and 42 ℃, and the pressure is 1.20MPa; the acid liquor cleaning tank is an 8% H ₂SO₄ solution, the temperature is controlled at room temperature, and the pressure is controlled at 0.30MPa; the temperature of the water rinsing tank is controlled at room temperature, and the pressure is controlled at 0.30MPa. The alkali liquor cleaning tank of the steel wire adopts 10% NaOH solution, the temperature is controlled between 38 ℃ and 42 ℃, and the pressure is 1.25MPa; the acid liquor cleaning tank adopts 10% H ₂SO₄ solution, the temperature is controlled at room temperature, and the pressure is controlled at 1.25MPa; the temperature of the water rinsing tank is controlled at room temperature, and the pressure is controlled at 0.30MPa.

Further, when the steel wire is zinc coated by an extrusion coating machine, the process temperature for extrusion coating is 400-500 ℃. Thus, it is required to preheat the wire to a temperature that normally achieves proper compounding at a temperature of between 360-420 ℃. Therefore, an intermediate frequency induction heater can be used to raise the temperature of the wire prior to compounding. The power supply device of the intermediate frequency induction heater is a variable frequency heater, and consists of a silicon controlled rectifier, a tuning capacitor and an inductor. Alternating current is converted to direct current by a thyristor string and the direct current is converted to the desired frequency by a tuning capacitor and inductor. The circuit also comprises a working coil and a compensation capacitor. When the steel wire is heated, nitrogen with the purity of more than 99% is also required to be filled in the steel wire so as to protect the surface of the steel wire from being oxidized.

Particularly, the hardness of water in a part of areas is relatively high, so that scale can be generated when the hard water is used for cooling the extrusion wheel, and a cooling water tank in the extrusion wheel is blocked; to avoid this, it is usual to soften the cooling water of the extrusion wheel, i.e. to use a hard water softening device.

Specifically, nitrogen is required to be provided for protection in the preheating process of the steel wire; the process requires a nitrogen delivery device. The flow rate of nitrogen and the purity of nitrogen are maintained during the operation, the nitrogen consumed during the extrusion process is about 1.2m ²/h, and the purity of nitrogen is controlled to be not less than 99%.

Furthermore, the zinc-coated steel wire after extrusion composite processing treatment is also required to be cooled by a cooling water tank; the cooling water tank is divided into two parts, wherein the first half part of the cooling water tank is a circulating water tank, and the heat of the zinc-coated steel wire needs to be taken away at the highest speed; while the rear half may employ a stationary sink. The temperature of the zinc-coated steel wire can be reduced to about 40 ℃ through the cooling action of the two cooling water tanks, and then a blowing device is arranged at the outlet of the cooling water tanks; so that the water on the zinc-coated steel wire can be dried.

Further, in the production of zinc-coated steel wires, when the steel wire is compounded with the zinc rod in the coating die cavity, the steel wire is subjected to the action of the extrusion stress field, so that the resistance to the movement of the steel wire is formed. If no drawing force is applied to the steel wire in the wire-outlet direction, the coated wire cannot be extruded from the die cavity. Therefore, a tension wheel is selected to apply a tension to the zinc-coated steel wire at the rear of the cooling water tank so as to lead the steel wire to be under the action of constant tension. If the tension of the steel wire is less than the resistance of the extrusion stress field, the steel wire cannot be pulled out smoothly; if the tension of the steel wire is too large, when the heating temperature of the steel wire fluctuates greatly or the residence time in the die cavity is longer, the phenomenon that the steel wire is broken easily occurs when the temperature of the steel wire rises too much. Thus, the tension pulley is selected to provide a traction force in the range of 2000-5000N. In addition, because the steel wire and the zinc rod are not under the traction action of the tension wheel in the earlier stage and the later stage of the coating process, the head section and the tail section of the zinc covered steel wire processed by the extrusion coating machine are all required to be cut off, and the processed zinc covered steel wire also needs to be detected in real time on an automatic production line so as to ensure the production quality of the zinc covered steel wire. Finally, a gantry winding and arranging machine with a speed control system can be used for winding and arranging the zinc-coated steel wires, and the maximum winding and arranging speed is more than 160m/min.

Specifically, in the foregoing steps, the extrusion process of cladding the steel wire and the zinc rod may be completed by an extruder. The main frame of the extruder may be mounted from a structure that is fabricated as a single unitary structure. The upper part of the main frame is a main transmission and a transmission supporting system thereof, and the lower part of the main frame is provided with a main bearing device with a cooling circulation system and a hydraulic system. The main transmission is formed by coupling a variable speed motor with a three-stage helical gear reduction box. The upper part of the extruder is provided with a detachable mould shoe, and the side surface of the mould shoe is provided with an air pump and a liquid storage tank device; the air pump and the liquid storage tank device are used for pneumatic loading and unloading of the die shoe. In addition, a feeding sub-wheel is arranged in the main frame, and the feeding pinch roller is used for guiding raw materials to enter the main extrusion wheel groove; the rotating shaft of the feeding pinch roller is installed and operated on a ball bearing with high bearing capacity. The guide wheel, the scraper and the baffle are arranged at the inlet side of the steel wire entering the extrusion wheel, and the scraper is mainly used for removing the accumulation of zinc raw materials so as to avoid the zinc materials from being accumulated and exposed outside the die shoe. The baffles are primarily used to prevent scraped zinc fines from falling over the passing wire and being carried into the extrusion groove. The extrusion wheel arranged on the extruder adopts a single-wheel double-groove structure, and is automatically controlled by a computer in the zinc-coated steel wire full-production line so as to ensure that the technological parameters such as the rotation speed of the extrusion wheel, the preheating temperature of the steel wire, the line speed, the tension and the like are kept in dynamic mutual coordination, thereby realizing the automation of the coating production process of the insulated wire and the cable.

Furthermore, the assembly mode of the single-wheel double-groove continuous extrusion die is two radial modes and tangential modes. Wherein, radial assembly is to put the mould in the radial of extrusion wheel, and the product is also by the radial extrusion of extrusion wheel. The tangential die is assembled by placing the die in the tangential direction of the extrusion wheel, and the product is extruded in the tangential direction. In the invention, a tangential assembly mode is preferably adopted, and the mold core of the assembly mode is fixed at the tangential position of the middle extrusion wheel of the arc-shaped curved surface sector corresponding to the groove of the extrusion wheel by using a screw. Therefore, the tangential assembly mode has the advantages of the radial assembly mode, and the extrusion force born by the die core screw is smaller, so that the die core screw is not easy to deform, and the design tolerance of extruded materials can be ensured. In addition, the plastic flow of the extruded metal enters the cavity from the extrusion wheel groove in the radial direction relative to the extrusion wheel, and then the plastic flow direction is changed so as to extrude the die hole tangentially relative to the extrusion wheel to form the pipe. Although the plastic flow mode needs large extrusion force for metal materials, the plastic flow is more uniform, and the quality of the zinc-coated steel wire can be ensured. Further, referring to fig. 3, fig. 3 is a schematic diagram illustrating a design of a composite mold in an automatic coating process for insulated wires and cables according to an embodiment of the present invention. In connection with fig. 3, in the design of the zinc coated steel production mould, the mould may be designed as a mosaic mould. The die holder is made of A.I.S.H.13 die steel, and the mosaic die is made of CR13 hard alloy steel; and the die holder hole is smaller than the die core by 0.08mm, after surface quenching, the die core is pressed in after the hole temperature is heated to 550-600 ℃. The die angle of the extrusion die was chosen to be α=10°. Since extrusion is performed at a temperature of about 500 c while considering thermal expansion of the zinc rod raw material, margin coefficient of the die hole should be considered in designing the die hole size, and thus, the diameter of the die hole is selected to be 0.07mm larger than that of the product, so as to avoid the product from being out of compliance with quality requirements due to the reduced temperature. The design of the extrusion die and the guide die according to the size of the composite cavity and thus the size of the die is now performed according to the conventional die cavity, as shown in tables 1 and 2 below.

Table 1: parameters of extrusion die

Table 2: guiding mode parameters

Further, after the steel wire and the zinc rod are pretreated, the steel wire and the zinc rod enter a continuous extrusion compounding machine to complete the compounding process. During the zinc coating of the steel core, it is required that the steel core, which is maintained at a certain movement speed and tension, passes through the mould cavity. Zinc in plastic flow is extruded into a die cavity to be directly compounded on a steel core, the temperature of the zinc can reach about 350 ℃ at the moment, and the extrusion force of the zinc can reach more than 800 MPa. Under the action of high temperature and high pressure, good interface bonding can be formed between the steel and the zinc, so that the metallurgical bonding requirement is met. In the foregoing steps, the temperature and speed parameters of a specific extrusion compounding process are shown in tables 3 and 4.

Table 3: temperature parameter of zinc-coated steel continuous extrusion process

Table 4: extrusion speed parameter of zinc-coated steel wire

In the extrusion compounding process of the zinc-coated steel wire, the following process parameters determine the quality and productivity of the product. 1. Zinc deformation temperature: during the compounding process, the zinc is in a plastic state, while the steel core is in an elastic state and plastic deformation is not allowed to occur. The deformation temperature of zinc is high, so that the deformation force is small, and the plastic flow is good, thereby being beneficial to uniformly compounding on the steel core and further improving the bonding strength between the steel and the zinc. 2. Rotation speed of the extrusion wheel: the extrusion wheel speed determines the speed of the composition between zinc and steel. The increase in speed means an increase in production efficiency. However, too high a speed results in an increase in zinc flow non-uniformity, which is detrimental to improving the quality of the bond between steel and zinc and the uniformity of the zinc layer thickness. 3. Preheating temperature of steel wire: the proper preheating temperature of the steel wire can ensure the normal operation of the compounding process. If the preheating temperature of the steel wire is too low, the steel wire absorbs a large amount of heat in the die cavity to reduce the zinc deformation temperature, thereby increasing the extrusion force. In severe cases, zinc is blocked at the die due to its increased resistance to deformation, resulting in the compounding process being interrupted. Meanwhile, too low extrusion temperature leads to poor zinc fluidity and also leads to low bonding strength between steel and zinc. If the preheating temperature of the steel wire is too high, the strength of the steel wire is reduced, and the steel wire is easily broken under the action of extrusion force and traction force. 4. Wire speed: the wire running speed must remain matched to the composite speed. If the running speed of the steel wire is too high, the phenomenon of package leakage is easy to occur. Otherwise, if the running speed of the steel wire is insufficient, the leakage degree of zinc materials is serious, and the defect of overload of the extruder is caused. 5. Wire tension: in the die cavity, resistance to movement of the wire is created by the wire being subjected to a compressive stress field. The resistance is related to the product specifications. The tension applied to the wire must be greater than this resistance to achieve the compounding process. However, the tension of the steel wire is not too high, otherwise the phenomenon that the steel wire is broken easily occurs. Based on the mechanism, the automatic coating process of the insulated wire and the cable provides matched process parameters in the steps.

Further, based on the zinc-coated steel wire obtained in the previous step, the continuous extrusion process is continuously used to coat the surface of the zinc-coated steel wire with the insulating sheath. The insulating sheath can be made of fluoroplastic, such as polytetrafluoroethylene PTFE, perfluoroethylene propylene copolymer FEP, fusible polytetrafluoroethylene PFA or ethylene-tetrafluoroethylene copolymer ETFE, and the like, and the latter three fluoroplastic can be formed by adopting an extrusion mode. Although the melt viscosity of the fluoroplastic melt is high, it is difficult to produce the fluoroplastic melt by extrusion at high speed during processing, such as polyethylene PE, but the fluoroplastic melt has sufficient strength and stretching-permitting properties, and thus can be produced by extrusion tube extrusion. The fluoroplastic has no limit to production equipment and production process at low speed, namely at a speed of not more than 150m/min when the tubular extrusion production is carried out. Specifically, the extrusion system of the insulating sheath mainly comprises a feeding system, an extruder, a machine head forming system and the like. A paying-off device is required to be arranged before the extrusion system so that the zinc-coated steel wire can be pulled into the extrusion system; the traction force is provided by a traction device arranged after the extrusion system. And then coiling and discharging the zinc-coated steel wire cable product which is coated with the insulating sheath by a coiling device. And the continuous extrusion process adopts an automatic control system to manage and control the continuous extrusion process in the whole process, so that the automatic and stable production of the product is realized. And the zinc-coated steel wire after the insulation sheath is processed can be handed over and put in storage.

Further, the technical problems of broken core wires, loose welding seams, eccentricity and the like easily occur in the production of zinc-coated steel wires in the prior art. Based on the product prepared by the steps, whether the zinc-coated steel composite wire is easy to have the defects of core wire fracture, loose welding line or eccentric can be evaluated through the interface bonding strength. Specifically, the section of the zinc-coated steel wire can be observed by using an interface scanning electron microscope, so that all products are free from eccentric conditions, and the interface joint of zinc and a rigid joint presents a fine saw tooth shape, which indicates that the interface joint of the conforming material is good metallurgical joint. In addition, tensile shear was used to determine the interfacial bond strength of zinc clad steel composite wires. The bond strength measured in this way is tensile shear, which indicates how much axial tension is experienced per annular bond area before interfacial fracture occurs. Specifically, the peel strength can be expressed by using the peel force between the bimetal in a unit area, and the formula is calculated as follows: peel strength (MPa) =peel force (N)/peel area (mm ²). The interfacial bonding strength of the zinc-coated steel composite material obtained through the tensile-shear test using the formula is shown in table 5. As can be seen from Table 5, the average tensile shear strength of the interface of the zinc-coated steel is about 158Mpa, which is equivalent to the tensile strength of metallic zinc, which indicates that the interface bonding of the zinc-coated steel composite wire prepared by the continuous extrusion coating method is metallurgical bonding.

Table 5: interface bonding strength of zinc-coated steel measured by tensile shearing method

The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.

The above examples illustrate only a few embodiments of the invention, which are described in detail and are not to be construed as limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. Accordingly, the scope of protection of the present invention is to be determined by the appended claims.

Claims

1. The automatic coating process for the insulated wire and the cable is characterized by comprising the following steps of:

2. An automatic coating process for insulated wires and cables according to claim 1, wherein: in step S1, the original structure of the wire is sorbite, and the disk weight of the wire is greater than 1 ton.

3. An automatic coating process for insulated wires and cables according to claim 1, wherein: in the step S1, the online cleaning process of the steel wire or the zinc rod comprises an alkali liquor cleaning tank, an acid liquor cleaning tank and a water rinsing tank; and the rinsing tank is provided with a vibration damping device for preventing vibration of the raw materials; and the outlets of the rinsing tanks are provided with blowing devices to blow the cleaned raw materials dry.

4. An automatic coating process for insulated wires and cables according to claim 3, wherein: the alkali liquor cleaning tank for the steel wire adopts 10% NaOH solution, the temperature is controlled between 38 ℃ and 42 ℃, and the pressure is 1.25MPa; the acid liquor cleaning tank adopts 10% H ₂SO₄ solution, the temperature is controlled at room temperature, and the pressure is controlled at 1.25MPa; the temperature of the water rinsing tank is controlled at room temperature, and the pressure is controlled at 0.30MPa.

5. An automatic coating process for insulated wires and cables according to claim 3, wherein: the alkali liquor cleaning tank of the zinc rod is 10% NaOH solution, the temperature is controlled between 38 ℃ and 42 ℃, and the pressure is 1.20MPa; the acid liquor cleaning tank is an 8% H ₂SO₄ solution, the temperature is controlled at room temperature, and the pressure is controlled at 0.30MPa; the temperature of the water rinsing tank is controlled at room temperature, and the pressure is controlled at 0.30MPa.

6. An automatic coating process for insulated wires and cables according to claim 1, wherein: in step S2, the intermediate frequency induction heater includes a silicon controlled rectifier, a tuning capacitor, and an inductor.

7. The automatic cladding process for insulated wire and cable according to claim 6, wherein: alternating current is converted into direct current through a silicon controlled rectifier group, and the direct current is converted into preset frequency through a tuning capacitor and an inductor.

8. The automatic cladding process for insulated wire and cable according to claim 7, wherein: in step S3, the cooling water of the pinch roller is softened by a hard water softening device.