KR20140115429A - Method for manufacturing steel strand with the function of sensing strain and steel strand manufactured thereby - Google Patents

Abstract

The present invention relates to a method for manufacturing steel strand having a function of sensing strain, capable of easily manufacturing steel strand with an optical fiber sensor inserted therein to enhance mass-productivity, guarantee quality management and performance, and provide excellent on-site workability, and steel strand manufactured thereby. The method for manufacturing steel strand having a function of sensing strain according to the present invention, as a method for manufacturing steel strand by using a mold for molding a bar-shaped molded product with grooves in a lengthwise direction, comprises a fiber material supply step of unrolling a fiber material wound around a roll; a fiber material immersion step of applying a resin solution to the fiber material supplied in an unrolling manner or immersing the fiber material in a resin solution; a central line molding step of injecting the fiber material with the resin solution applied thereto of the immersed fiber material to the mold to mold a central line with trenches formed as grooves thereon; an optical fiber installation step of insertedly fixing an optical fiber with a plurality of strain sensors formed therein to the trenches of the central line; and a lateral line coupling step of coupling a plurality of unit steel strands around the central line with the optical fiber installed therein in a twisting manner.

Description

TECHNICAL FIELD [0001] The present invention relates to a method of manufacturing a strand with a strain sensing function and a strand produced by the method.

The present invention relates to a method of manufacturing a strand, more particularly, to a method of manufacturing a strand with a strain sensing function capable of measuring and monitoring the strain of the strand of the structure according to deformation of the structure and a strand produced thereby.

Since the stranded wire has flexibility, it is easy to arrange the curve and is easy to construct, and it is widely used as a tension material and bridge cable of PC method, and it is widely used as a construction material such as other soilless nailing and rock bolts.

Such a stranded wire has a crucial effect on the structural stability of the structure because it acts to generate a resistance force against the external force by applying a tensile force in the structure, and monitoring and measurement of the state of the tensile strength is very important factor .

As a method for monitoring and measuring the tension of a conventional stranded wire, a load cell method and an indirect method using an accelerometer are predominant. First, the method using a load cell has a disadvantage in that the price is relatively high and a measurement error due to eccentricity is largely generated. Next, in case of the indirect estimation method using an accelerometer for measuring the cable tension of a cable-stayed bridge, there is an estimation error, and there is a disadvantage that it is impossible to measure the tension of the PSC structure inserted in the concrete and subjected to grouting treatment.

In order to overcome these disadvantages and limitations, a technology for monitoring and measuring the tension of the strand by replacing the core wire in the center of the strand with the inserted kingwire of the FBG fiber optic sensor ("Patent Document 1") has been proposed. However, in the case of the FBG fiber optic sensor built in the center of the strand, it is possible to improve the measurement sensitivity and simultaneously measure the tensile force at a plurality of points.

(1) Since hollows are formed in the longitudinal direction of the elongated core wires, it is difficult to manufacture the core wires, and it is difficult to fix the optical fibers to the hollow of the core wires.

(2) When the resin is injected to insert the optical fiber into the hollow of the king wire (core wire) and fix it in the hollow, it is difficult to inject the resin accurately due to the viscosity of the resin and the accurate sensing of the optical fiber sensor It is difficult to secure the quality control and the performance.

(3) When cutting the end of the strand after the installation in the field, the end of the optical fiber must be taken out to connect the optical fiber to the external equipment. However, since the operation of exposing only the optical fiber to the outside of the end of the strand is difficult, .

Patent Document 1: Korean Patent No. 10-0756056 (Registered Date: Aug. 30, 2007)

SUMMARY OF THE INVENTION The present invention has been conceived to solve the problems as described above, and it is an object of the present invention to provide an optical fiber sensor which can easily mount the optical fiber sensor, improve mass productivity, ensure quality control and performance, And a method of manufacturing a stranded wire having a sensing function.

According to another aspect of the present invention, there is provided a method of manufacturing a stranded wire having a strain sensing function, the method including: fabricating a stranded wire using a mold for molding a rod- A fiber substrate feeding step for feeding the fiber substrate; A fiber substrate impregnation step of applying a resin solution or impregnating the fiber base material to be fed and fed into a vertical solution; A center line forming step of injecting the fiber base coated or impregnated with the resin solution into the mold to form a center line in which the trench made of the material groove is formed; An optical fiber mounting step of inserting and fixing an optical fiber formed with a plurality of strain sensors into the trench of the center line; And a sideline joining step of twisting a plurality of unit strands around the center line where the optical fiber is installed.

According to the method for manufacturing a strand having a strain sensing function according to the present invention, it is possible to easily and precisely manufacture a strand with an inserted optical fiber sensor, thereby improving mass productivity, ensuring quality control and performance, The operation of drawing out the optical fiber to the outside of the stranded wire after the installation is convenient, so that the workability can be improved.

In addition, since the center line constituting the strand is very light, has a high tensile strength, and is resistant to an external impact, it is suitable as a strand to be installed in an external structure, Unlike the conventional stranded wire in which corrosion occurs due to the formation of a center line, it is possible to fundamentally remove the problem caused by corrosion (i.e., detachment / deformation of the attached optical fiber and the resulting malfunction of sensing).

Further, the optical fiber provided in some of the trenches has a gentle curved portion, so that the temperature can be compensated by the seasonal temperature change.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block flow diagram illustrating a process flow of a strand production method having a strain sensing function according to the present invention. FIG.
2 is a schematic view of an apparatus for manufacturing a strand having a strain sensing function according to the present invention.
3 is a schematic view of a strand produced according to the method of manufacturing a strand according to the present invention.
Figure 4 is a cross-sectional view of Figure 3;
5 is a first embodiment of a center line manufactured according to the method of manufacturing a strand of the present invention.
6 is a second embodiment of a center line manufactured according to the method of manufacturing a strand of the present invention.

In the following, preferred embodiments, advantages and features of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a block flow chart showing a process flow of a strand producing method having a strain sensing function according to the present invention, FIG. 2 is a schematic view of a device for manufacturing a strand having a strain sensing function according to the present invention, Fig. 4 is a cross-sectional view of Fig. 3, and Fig. 4 is a cross-sectional view of the strand of Fig.

Referring to FIGS. 1 to 4, a strand manufacturing method having a strain sensing function according to the present invention includes a mold and a resin preparation step, a fiber substrate supplying step, a fiber substrate impregnation step, a center line forming step, And a sideline joining step.

(1) Mold and resin preparation preparation step (S10)

The mold and the resin trench preparation step of the present invention is a step of preparing a mold 40 for molding a molded product of a predetermined shape and a resin tank 20 containing a liquid resin 30.

The mold 40 of the present invention is a mold die capable of manufacturing a bar-like member according to one of various plastic forming methods, and may be preferably formed of a draw-forming mold, but is not limited thereto. For example, if necessary, it may be constituted by an extrusion molding mold and an injection molding mold.

Particularly, the mold 40 is characterized in that at least one trench 110 is formed on the outer circumferential surface of the bar-shaped member formed through the mold 40. Here, it is preferable that the trench 110 formed by the mold 40 is formed in the shape of a shank groove continuously formed along the longitudinal direction of the bar-shaped member, and the shank groove is preferably formed in a straight shape.

The resin trough 20 of the present invention corresponds to a constituent part for impregnating the fiber base material 10 supplied from the fiber base roll 15 in a liquid state. In this case, the resin trough 20 is composed of a resin container in the form of a bath, the top surface of which is opened and the inside thereof is empty, and the fiber substrate 10, which is transported under the guidance of the guide rollers, The resin 30 is impregnated by the load.

It is needless to say that the resin bath may be constituted by a resin coating system in which a resin is flowed out to the fiber substrate 10 in addition to the impregnation system as described above. In this case, the resin reservoir is constituted by a pair of resin flow tanks configured to overflow to the outside when a predetermined amount of the liquid resin is filled in the inner space, and one of the pair of resin flow tanks is disposed on the front surface of the fiber base 10 And the other one is disposed on the rear surface of the fiber substrate 10 so as to have a symmetrical structure.

Here, when the liquid resin is continuously injected into the resin flow tank, the resin exceeds the maximum volume of the tank, and the overflowed resin flows out to the outside. In the resin flow out method, the resin To the fiber substrate 10 to be conveyed to apply the resin.

(2) Fiber substrate supply step (S20)

The fiber substrate supplying step of the present invention is a step of feeding and supplying the fiber substrate 10 to the resin tank 20, preferably by the fiber base roll 15 constituted by winding the fiber substrate 10 on the bobbin .

Preferably, the fiber-based roll 15 is in the form of a roll, which is in the shape of a cylinder and rotationally driven with respect to the central axis, and the surface layer corresponding to the outer circumferential surface of the roll is preferably made of an elastic material such as silicone rubber But is not particularly limited and may be composed of any one selected from the group consisting of isoprene rubber, polyamide thermoplastic elastomer, polyester thermoplastic elastomer and polyolefin thermoplastic elastomer. This is to ensure that the fiber substrate 10 is brought into contact with the frictional force of the roll surface layer so that the supply of the fiber substrate 10 can be performed smoothly.

The fiber substrate 10 wound around the fiber substrate roll 15 is composed of at least one fiber selected from glass fiber, carbon fiber, aramid fiber and Kevlar fiber. .

The plurality of fiber base rolls 15 may be composed of a plurality of fibers. In this case, a plurality of fiber base materials 10 fed in a plurality of fiber base rolls 15 may be simultaneously impregnated into the resin base 20, And is introduced into the rear mold 40.

Needless to say, a plurality of guide rollers 50 for guiding the conveyance of the fiber substrate 10 may be further provided between the fiber substrate roll 15 and the resin tank 20. [

(3) Fibrous base impregnation step (S30)

The fiber substrate impregnation step of the present invention is a step of applying a resin solution or impregnating the resin solution 30 to the fiber base material 10 fed from the fiber base roll 15 and fed.

Here, the resin solution 30 to be applied or impregnated to the fiber substrate 10 is a synthetic resin, preferably a UV curable resin or a thermosetting resin. Specific examples thereof include an unsaturated polyester, an epoxy resin, a polysulfone, a polyether , Polyether imide or polyarylate, and the like.

The step of applying or impregnating the resin solution to the fiber substrate may be carried out in such a way that the fiber substrate is immersed in the resin container containing the liquid resin as described above or the resin is flowed out by using the resin flow tank, It can be carried out in a coating manner.

(4) Center line forming step (S40)

The centerline forming step of the present invention is a process for producing a rod-shaped molding having a longitudinal grooved groove using the mold 40 described in step S10.

That is, when the resin solution is applied through step 'S30' or a fiber substrate (hereinafter, 'input material') impregnated with the resin solution is put into a molding machine having the mold 40 of step S10 ' Is formed by passing through the mold 40 and passing through the mold 40 according to a molding method (for example, drawing or the like) and being cured by the drying unit 60 provided when the mold 40 passes through the mold 40, (Hereinafter, referred to as "center line 100") in which the trenches 110 are formed.

The drying unit 60 provided in the mold 40 is configured to dry and cure the liquid resin 30 applied or impregnated to the fiber substrate 10 by the resin tank 20 to form a solidified molded product As part. As the drying / curing method, a UV curing method or a thermosetting method may be used. As the thermosetting method, a far infrared ray heating source, a resistance heating source, or the like can be used.

The center line 100 of the fiber reinforced plastic (FRP) material in which the fiber substrate 10 is mixed in the synthetic resin 30 is finally obtained through the steps S10 'to S40'.

The center line 100 thus prepared is lightweight, has a very high tensile strength, and is resistant to external impact, so that it is suitable as a strand to be installed on an external structure and has advantages of easy processing in the production of stranded wire. Especially, Unlike the conventional stranded wire in which corrosion occurs due to the formation of the center line 100, it is possible to fundamentally eliminate the problem caused by the corrosion due to the absence of corrosion (i.e., the deformation of the attached optical fiber and the resulting malfunctioning of the attached optical fiber).

(5) Optical fiber installation step (S50)

The step of installing the optical fiber of the present invention is a step of inserting and fixing the optical fiber 200 into the trench 110 formed on the outer peripheral surface of the center line 100.

The optical fiber 200 installed in the trench 110 of the center line 100 is a component for sensing the strain generated in the strand of the strand (i.e., the deformation of the center line caused by the deformation of the sidewall) It may further comprise a cover layer comprising glass fibers of glass cladding and wrapping around the glass cladding. The covering layer may be composed of one or a plurality of layers and may be formed of a synthetic resin material.

The optical fiber 200 may be configured as a cable consisting of a plurality of bundles. In this case, at least one of the optical fibers 200 is formed with a strain sensor 210 to perform a sensing function.

When the optical fiber 200 is configured in the form of a cable, the optical fiber 200 may further include a casing in the form of a tube or a rigid fiber surrounding the covering layer of the optical fiber.

In the case of a tubular shape, it may be formed as a strip or a wire of a metal material extending in a helical structure. In the case of a rigid fiber yarn, it may be formed of a suitable material such as aramid fiber, fiberglass or polyester.

In addition, it may further comprise a jacket made of a polymer material such as PVC, PVDF, or FRPE, or a metal braid in which a plurality of metal yarns are woven in the form of a fabric.

The strain sensor 210 formed on the optical fiber 200 may be a fiber Bragg grating (FBG) type optical fiber sensor. In this case, the strain sensor 210 generates a Bragg grating that reflects a specific wavelength to the optical fiber. Deflection, etc.), the change of the lattice spacing can be caused to correspond to the change of the tensile force of the strand.

By analyzing the wavelength variation of the reflected light by using the property that the wavelength of the reflected light is changed when the Bragg grating interval is changed, the strain of the strand installed in the structure can be measured and monitored.

The optical fiber 200 is inserted and fixed in the trench 110, preferably using a fixing agent, and a resin-based adhesive including an epoxy resin may be used as the fixing agent. In this case, a fixing agent is coated on the mounting surface of the optical fiber 200 and then inserted into the trench 110 to be hardened. Alternatively, the fixing agent is injected into the trench 110 into which the optical fiber 200 is to be inserted, ) And then curing it.

In the preferred embodiment, the fixing agent is used as the optical fiber fixing means, but it is needless to say that the optical fiber may be more firmly installed inside the trench 110 by further including a coating tape, a coupler, and the like.

A plurality of trenches 110 may be formed in the center line 100. In this case, the at least one trench (hereinafter, referred to as 'temperature correction trench') may be provided with an optical fiber 200 having the following structure In particular, measurement errors due to seasonal temperature changes can be corrected.

That is, the optical fiber provided in the temperature correction trench is installed in a structure capable of flowing without being attached or fixed to the trench by a fixing agent or the like.

Preferably, the optical fiber is loosely installed in a flowable and loose structure. Here, the optical fiber is loosely installed, meaning that the optical fiber is not installed in a straight line, and at least a part of the optical fiber is installed to have a curved portion curved in a gentle curved shape.

It is preferable that the curved portion is provided at a portion where a strain sensor (a Bragg grating) is formed.

In this case, the optical fiber loosely installed in the temperature correction trench does not react to the strain of the strand but reacts only with the temperature change. By using this for temperature correction, the strain sensor of the optical fiber fixed to the other trench compensates an error according to the seasonal temperature change .

(6) Siding joining step (60)

In the sidewall joining step of the present invention, a unit strand made of a single wire material of a metal material is prepared, and a strand is formed by joining a plurality of sidewalls 300 around the center line 100 in which the optical fiber is installed.

A stranded cable (steel strand) is a construction structure in which a plurality of strands are twisted in a twisted shape, and means a construction structural material used in a pre-stressing method. A plurality of strands And the center line 100 in which the optical fiber of the present invention is installed corresponds to the center core wire.

When the six side lines 300 are twisted and joined to one center line 100 of the present invention, a stranded wire of seven stranded wires is formed. When the eight side lines 300 are twisted to one center line 100 of the present invention 19 stranded wire.

Hereinafter, an article to be manufactured according to the steps of the above-described steps will be described.

5 and 6 are a first embodiment and a second embodiment of a center line manufactured according to the method of manufacturing a strand of the present invention.

5 and 6, it is possible to manufacture the center line 100 composed of the bar-shaped member having the trenches 110, in particular, the center line 100 The trench 110 is formed in the shape of a shank groove continuously formed along the longitudinal direction of the bar-shaped member.

The trenches 110 may be formed as one as shown in FIG. 5 or may be formed as shown in FIG. 6, and the shape of the trenches 110 is not particularly limited as long as the structure can stably receive the optical fibers. For example, the trench 110 according to the first embodiment of FIG. 5 is configured to have a substantially 'C' -shaped cross-sectional structure, and the trench 110 according to the second embodiment of FIG. 6 has a substantially ' Respectively.

An optical fiber is installed in the trench 110 of the center line 100 as described above.

The optical fiber is inserted into the trench 110 of the center line 100 and fixed by a predetermined fixing means. As described above, the fixing means for fixing the optical fiber can use a resin-based adhesive including an epoxy resin.

When the center line 100 provided with the optical fiber on the trench 110 is provided, the plurality of the side lines 300 are twisted to the outer circumferential surface of the center line 100 through the step S60 ' A strand with a function is finally completed.

When the manufacture of the strand is completed, a prestress is applied to the concrete used for the construction of the structure (for example, a bridge, etc.) by using the strand as a tension member.

The optical fiber is connected to an external measuring device. The measuring device is a device connected to a strain sensor through an optical fiber to measure a strain signal of the structure.

Specifically, the measuring device is connected to the end portion of the optical fiber drawn out from the strand, and after the light is applied to the optical fiber, whether the wavelength of the light reflected back from the respective strain sensors connected in series to the optical fiber is changed is analyzed It is possible to calculate the strand strain rate at the point where the strain sensor is installed, thereby realizing management and measurement of deformation (e.g., deflection, etc.) of the structure in real time.

While the preferred embodiments of the present invention have been described and illustrated above using specific terms, such terms are used only for the purpose of clarifying the invention, and it is to be understood that the embodiment It will be obvious that various changes and modifications can be made without departing from the spirit and scope of the invention. Such modified embodiments should not be understood individually from the spirit and scope of the present invention, but should be regarded as being within the scope of the claims of the present invention.

Also, the singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises" or "having" and the like are used to specify that there is a feature, a number, a step, an operation, an element, a component or a combination thereof described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

10: fiber substrate 15: fiber-based roll
20: Resin tank 30: Liquid resin
40: Mold 60: Drying part
100: center line 110: trench
200: optical fiber 210: strain sensor
300: sideline

Claims (9)

A method for manufacturing a stranded wire having a strain sensing function by using a mold for molding a rod-shaped molding having a longitudinal grooved groove,
A fiber substrate feeding step of winding a fiber substrate wound on a roll;
A fiber substrate impregnation step in which a resin solution is applied or impregnated into a vertical solution to the fiber substrate to be fed and fed;
A center line forming step of injecting the fiber substrate coated or impregnated with the resin solution into the mold to form a center line formed with the trench made of the material groove;
An optical fiber mounting step of inserting and fixing an optical fiber formed with a plurality of strain sensors into the trench of the center line; And
And a line connecting step of connecting a plurality of unit strands by twisting around the center line where the optical fiber is installed.
The method according to claim 1,
Wherein the step of installing the optical fiber comprises attaching and fixing the optical fiber inside the trench using a fixing agent. The method according to claim 1,
The trenches are formed in a plurality of trenches,
Wherein the optical fiber installed in at least one of the plurality of trenches is installed in a structure capable of flowing without being fixed or attached to the trench.
The method of claim 3,
Wherein the optical fiber installed in a structure capable of flowing in the trench is provided such that at least a portion where the strain sensor is formed has a curved portion curved in a gentle curved shape.
The method according to claim 1,
Wherein the trench is formed in a 'C' -shaped or '-V' -shaped cross-sectional structure.
The method according to claim 1,
Wherein the resin solution is a UV curable or thermosetting resin,
Wherein the fiber substrate is at least one selected from glass fiber, carbon fiber, aramid fiber and Kevlar fiber.
The method according to claim 1,
Wherein the center line forming step is performed by a draw-forming method.
The method according to claim 1,
Wherein the strain sensor is a Bragg grating sensor.
A stranded wire having a strain sensing function,
A strand with a strain sensing function, which is manufactured by the manufacturing method according to any one of claims 1 to 8, and has an optical fiber with a strain sensor formed therein inserted in a center line located at the center of the strand .

Images