JP2015004569A - Resin-coated pinhole testing method of resin-coated steel material and testing device of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve workability in pinhole testing of an outer cable.SOLUTION: A pinhole testing machine consists of a ground plate 10 as an indirect ground, a semi-annular brush electrode 11, and a detector 13 to which the ground plate 10 and a brush electrode are connected via cables 12a, 12b. The ground plate covers and is fixed to a surface outer periphery of a PC steel material B, which constitutes an outer cable, a voltage of 3 kV is applied between the ground plate and the brush electrode, and the brush electrode is moved in the peripheral surface longitudinal direction of the PC steel material. This movement performs testing of a half peripheral surface of the PC steel material in a forward path, and moves the brush electrode 11 by a half periphery to perform testing of an opposite half peripheral surface in a return path. When a pin hole exists in a clad of epoxy resin 1b according to the movement of the brush electrode, electric discharge occurs between the brush electrode and a steel element wire 1a via the pin hole, a current flows in a loop circuit consisting of the PC steel material, the ground plate, a cable, a detector, a cable, and the brush electrode, an ammeter detects the current, and a lamp is lighted or the like in the detector to notify a user of the presence of the pin hole.

Description

  The present invention relates to a resin-coated pinhole test method for a resin-coated steel material such as an outer cable and a test apparatus therefor.

  For example, as shown in FIG. 5, an external cable method using an external cable is a press stressing method in which the PC steel material B is installed outside the concrete member C, and the PC steel material B is disposed inside the concrete member C. Differentiated from the inner cable method. In this outer cable structure, the thickness of the concrete member C can be reduced and the weight of the web C1 can be reduced by taking out the PC steel material B arranged in the web C1 such as a bridge. Is possible.

In this outer cable structure, the PC steel material B forming the outer cable is, for example, as shown in FIG. 5, a deflection part C3 on the upper surface of the lower floor slab C2, and a cross beam C5 between the upper floor slab C4 and the lower floor slab C2. Is provided in the length direction of the web C1 (see Patent Document 1 FIGS. 1 to 3).
As the PC steel material B, for example, a steel material B shown in FIG. 6 in which a stranded wire of a steel wire 1a is resin-coated with an epoxy resin 1b and the stranded wire 1 of the resin coating is further twisted ( (See Patent Document 2 FIG. 11).

JP 2001-32211 A JP 2000-96470 A JP 2001-221765 A

  Since the outer cable B arranged in the concrete member C such as a bridge is exposed to the outside of the concrete member C, the resin coating of the stranded wire 1 is caused by collision with another member during or after the construction. Pin holes such as holes and scratches may occur in 1b. For this reason, the presence or absence of the pinhole is detected (tested) immediately after the construction and every certain period after the construction. In the pinhole test, a ground electrode is installed at an arbitrary location on the outer cable B, and a detection electrode such as a brush electrode electrically connected to the ground electrode is slid on the resin-coated surface of the outer cable B. If there is, a discharge occurs between the detection electrode and the stranded wire 1 (steel element wire 1a), so that a current flows through the loop circuit of the ground electrode, the stranded wire 1 and the detection electrode. The presence / absence (current flow) of this current is detected by a detector provided between the ground electrode and the detection electrode to detect the presence / absence of a pinhole (see embodiment below).

The ground electrode in the conventional pinhole test of the outer cable B in the bridge is usually attached to the outer tube protection steel pipe b of the deflection section C3 (see FIG. 5). This is because there is no metal plate serving as a ground other than the protective steel pipe b in the concrete member C.
On the other hand, since the pinhole test of the outer cable B extends to several tens of meters, the detection electrode is disposed on the outer cable B that is several tens of meters away from the deflection unit C3. Therefore, if the detector is on the ground electrode side, the detection-side cable is routed for several tens of meters. If the detector is on the detection electrode side, the ground-side cable is routed for several tens of meters. In any case, routing a cable of several tens of meters is cumbersome and the workability is poor.

  This invention makes it a subject to improve the workability | operativity of the pinhole test of resin-coated steel materials under the above actual condition.

  To achieve the above object, the present invention provides a resin-coated pinhole test apparatus for a resin-coated steel material, wherein the resin-coated steel material is provided with an earth plate that is placed on the surface of the resin-coated steel material and serves as an indirect ground, A resin-coated steel material having a detection electrode that slides on the surface, and a detector that is provided between the ground plate and the detection electrode, applies a required voltage between the two, and detects the presence or absence of a current between the two. This is a resin-coated pinhole test device.

  Also, a method for testing the presence or absence of a resin-coated pinhole in a resin-coated steel material, wherein the resin-coated steel material is covered with a ground plate serving as an indirect ground, and the resin is different from the covering position of the ground plate A detection electrode is applied to the surface of the coated steel material, and the required voltage is applied between the ground plate and the detection electrode, and the detection electrode is slid on the surface of the resin-coated steel material. This is a resin-coated pinhole test method for a resin-coated steel material in which when the current is generated between the detection electrodes, the resin-coated pinhole is located at the sliding position of the detection electrode.

  As described above, since the ground electrode is constituted by the ground plate, the present invention can be grounded by covering the ground electrode at an arbitrary position in the length direction of the resin-coated steel material. For this reason, even in detection over several tens of meters, the ground position can be changed as appropriate. Therefore, the cable length between the ground electrode and the detection electrode may be as short as 2 meters, for example, and the workability is improved. It will be good.

1 is a partially omitted perspective view of an embodiment of a resin-coated pinhole test apparatus for resin-coated steel materials according to the present invention. It is operation | movement explanatory drawing of the embodiment. It is a fragmentary perspective view of each example of the earth board of the embodiment. It is explanatory drawing of the pinhole detection test of the embodiment. It is a partially cutaway perspective view of a bridge by an outer cable construction method. It is sectional drawing of an example of an outer cable.

As the resin-coated steel material to be subjected to the pinhole test of the present invention, the outer cable, the rope, and the like are conceivable. The outer cable is not limited to the stranded wire 1 and may be a steel rod. This invention can be adopted even with PC steel that is not used. The PC steel material may have a configuration in which a plurality of stranded wires obtained by coating a stranded wire of a steel element wire with an epoxy resin are further twisted to expose the resin-coated stranded wire.
Further, the ground plate serving as the indirect arm according to the present invention can be slidable on the surface of the resin-coated steel material in the length direction thereof. In this way, the ground plate can be slid and attached to a required position in the length direction of the steel material without removing the ground plate from the resin-coated steel material one by one, and the workability is improved. At this time, the inner surface in contact with the surface of the resin-coated steel material of the ground connection ground plate is preferably subjected to a lubrication treatment.

  Further, the detection electrode has a semi-annular shape, and a pinhole is detected on the semi-circumferential surface of the surface of the resin-coated steel material by sliding in the length direction of the surface of the resin-coated steel material of the detection electrode. If pinhole detection on the opposite half circumferential surface where the hole is detected is performed, pinhole detection of the required length of the resin-coated steel material can be performed by one reciprocating sliding of the required length of the detection electrode.

  One embodiment of a pinhole test apparatus according to the present invention is shown in FIGS. 1 and 2, and this apparatus includes an earth plate 10 serving as an indirect earth, a brush electrode 11 serving as a detection electrode (probe), and the earth plate 10. And a detector 13 to which the brush electrode 11 is connected via cables 12a and 12b.

  The earth plate 10 is made of an aluminum plate, a steel plate, a copper plate, or the like, or a conductive flexible metal plate in which a foil thereof is bonded to a base material. ), Or by applying a conductive lubricant or the like. The size of the ground plate (metal plate) 10 is arbitrary as long as it has a contact area that can be an indirect ground, and in the embodiment, an A3 size stainless steel plate is used.

Edge pieces 10a and 10a are fixed to the short side of the ground plate 10, and the two edge pieces 10a are overlapped and fixed by a fastener 10b to form a circular cross section (droplet shape). The fastener 10b may be a known one such as a clip or a screw stopper. For example, as shown in FIGS. 1 and 2, the fastener 10b is fastened by screwing a thumbscrew penetrating the overlapping edge pieces 10a and 10a. Alternatively, as shown in FIG. 3 (a), the short-side edge of the ground plate 10 can be fastened with a hook-and-loop fastener 10d that is fixed to the inner surface without providing both edge pieces 10a and 10a. The number of wing screws 10b is arbitrary. Further, as shown in FIGS. 3B and 3C, the ground plate 10 abuts or overlaps both short sides without providing an edge piece, and the abutting edge is a zipper (wire fastener). ) 10e (the same figure (b), the overlapping edge can be fixed with a hook-and-loop fastener 10d (the same figure (c)). The edge piece 10a can also be provided as long as there is no hindrance to the fixing for reinforcing the side edge.
In any fixed state, the arc-shaped inner surface of the ground plate 10 is brought into contact with the outer peripheral surface of the PC steel material B with a certain pressure contact force, and the ground plate 10 becomes an indirect ground. A cable 12a is connected to the ground plate 10 through one edge piece 10a or directly, and a pull string 10c is provided.

  The brush electrode 11 has an arc shape (semi-annular shape), in which wire rods are radially arranged around the center axis of the arc shape, and is supported by a rod-shaped handle 11a. A cable 12b is inserted and fixed to the end of the handle 11a, and the cable 12b is electrically connected to the brush electrode 11 with a cable (not shown). The thickness and length of the handle 11a are appropriately determined in consideration of workability.

The detector 13 incorporates a battery (power source) E, an ammeter M, and the like, has a function necessary for detection, and is portable by providing a shoulder strap 13a.
The lengths of the cables 12a and 12b connected to the detector 13 may be appropriately determined so as not to hinder the work. However, since the grounding board side cable 12a is routed, the length does not hinder the routing. For example, the length is about 2 m, and the electrode-side cable 12 b has a length that does not hinder the sliding operation with the detector 13 carried, for example, about 1.5 m.

This pinhole test apparatus has the above-described configuration. For example, the pinhole test of the PC steel material B forming the outer cable shown in FIG. 6 provided on the bridge shown in FIG.
The PC steel material B is a stranded wire 1 (diameter: 15.2 mm) obtained by coating a stranded wire of seven steel strands 1a with an epoxy resin 1b and further twisting 19 of them.

As shown in FIG. 2, the test specifications are as follows. First, the ground plate 10 is placed on the outer periphery of the surface of the PC steel material B to be tested, for example, the center of the range of 4 m in length (2 m from the end of the range). Is fixed in a circular shape (see FIG. 4B).
Next, in a state where a voltage of 3 kV is applied between the ground plate 10 and the brush electrode 11, the brush electrode 11 is moved in the circumferential direction (a arrow direction in FIG. 2) at a required position of the PC steel material B. (Sliding) (see Patent Document 3).
At this time, along with the movement of the brush electrode 11, if there is a pinhole in the covering of the epoxy resin 1b in the movement range, a discharge occurs between the brush electrode 11 and the steel wire 1a through the pinhole, A current flows through the loop circuit of the PC steel material B, the ground plate 10, the cable 12a, the detector 13, the cable 12b, and the brush electrode 11, and the ammeter M detects the current. By this detection, the detector 13 turns on a lamp, blinks, or sounds a buzzer to notify the presence of a pinhole.

  In this operation, the brush electrode 11 is moved in the length direction of the PC steel material B (the arrow b direction in FIG. 2), and the PC within the moving range of the cable 12a from the ground plate 10 (for example, within 2 × 2 = 4 m). This is performed on the steel material B, and the presence or absence of a pinhole within the range is detected. At this time, it is preferable to mark the detection range. When the pinhole detection within the moving range of the cable 12a is completed, the ground plate 10 is moved in the length direction of the PC steel material B, for example, 4 m, and then the pinhole detection is performed by the same operation. Thereafter, the pinhole detection of the required length of the PC steel material B is performed in the same manner. Note that the detection range may be a moving range of the cable 12a from the ground plate 10 to one side (for example, 2 m, see FIG. 4A).

  In addition, as shown in FIG. 2, when the arc-shaped brush electrode 11 is in contact with half or more of the peripheral surface of the PC steel material B, the movement of the brush electrode 11 in the length direction of the PC steel material B is performed as shown in FIG. (Sliding) It is also possible to test the half of the peripheral surface of the PC steel material B in the forward path, and to perform the test of the peripheral surface half that could not be tested by moving the brush electrode 11 by half a circle on the return path ( See arrow). At this time, as shown in FIG. 9A, there are cases where the earth plate 10 only moves in one direction, and as shown in FIG. 10B, the earth plate 10 moves in both the left and right directions. It is done. In this case, the test range L is the routing range of the cable 12a from the ground plate 10 (the movement range of the brush electrode 11), which is 2 m in the former case and 4 m in the latter case, for example.

During these operations, the ground plate 10 may be moved by loosening the thumbscrew 10b or the like, or may be moved without loosening the thumbscrew 10b or the like if it can be moved by the smooth surface. Moreover, the pull string 10c is used for the movement. At this time, if the ground plate 10 can be moved via the pull string 10c according to the movement of the operator, the brush electrode 11 is slid while sliding the ground plate 10 on the surface of the PC steel material B. Can be detected. That is, the required length of the PC steel material B can be continuously tested.
Furthermore, when the detection test is performed by the reciprocating sliding, if the ground plate 10 can move along with the movement of the operator, the length of the PC steel material B to be tested, for example, several tens of meters, A person can reciprocate and perform a test for the test length of the PC steel material B by performing a test for each half circumferential surface of the PC steel material B in the reciprocating path. At this time, the return path detection test is performed after the ground plate 10 is moved to the end of the forward path detection test.

  In the PC steel material B of this embodiment, pinholes in the outermost layer (1:12 strands) of the epoxy resin coating 1b are detected, and the coating 1b is made of the same material and has a constant discharge withstand voltage. Therefore, stable pinhole detection can be performed by sliding the indirect ground (ground plate 10) and the brush electrode 11. Usually, when manufacturing PC steel, a pinhole test of the resin coating 1b is performed, and the pinhole test after construction is a pinhole consisting of scratches caused by collision with other members during construction or after construction. Therefore, it is sufficient to detect the outermost layer. Further, since the ground plate 10 has a constant size, the ground area is also constant, and the detection accuracy is stabilized.

Although the said embodiment was PC steel material B shown in FIG. 6, PC steel material which provided the sheath in the outer periphery, The strand wire of the steel strand 1a is a steel rod, The PC steel material from which the twist number of the strand wire 1 differs Furthermore, it goes without saying that the present invention can be adopted as long as it is a steel material coated with resin such as a rope other than the outer cable. However, as for this invention, it is preferable that the resin coating of a pinhole test is one layer like the PC steel material B of the said embodiment. Moreover, this invention can be used not only for the resin-coated steel material after construction but also for pinhole detection (testing) of the resin-coated steel material during production. Furthermore, the resin coating is not limited to an epoxy resin.
Thus, it should be thought that embodiment disclosed this time is an illustration and restrictive at no points. The scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 1a Steel strand 1b Epoxy resin coating 1 Stranded wire 10 Indirect grounding ground plate 10a Ground plate edge piece 10b Ground plate both-sides fixing thumb screw 10c Grounding plate pull string 10d Grounding plate both-side surface fixing surface fastener 10e Zipper 11 for fixing both edges of ground plate Detection electrode (brush electrode)
12a, 12b Cable 13 Detector B PC steel (outer cable)
E Power supply M Ammeter C Concrete member (bridge)
C1 Bridge web C2 Lower floor slab C3 Deflection section C4 Upper floor slab C5 Cross beam

Claims (11)

  A resin-coated pinhole test apparatus for resin-coated steel material, comprising: a ground plate that is placed on the surface of the resin-coated steel material to be an indirect ground; a detection electrode that is slid on the surface of the resin-coated steel material; A resin-coated pinhole test apparatus for a resin-coated steel material, comprising a detector provided between a plate and a detection electrode, for applying a required voltage between the two and detecting the presence or absence of a current between the two.   2. The resin-coated pinhole test apparatus for a resin-coated steel material according to claim 1, wherein the resin-coated steel material is an outer cable.   3. The resin-coated steel material according to claim 2, wherein the outer cable is a PC steel material in which a plurality of stranded wires obtained by coating a stranded wire of a steel wire with an epoxy resin are further twisted and the stranded wire coated with the resin is exposed. Resin-coated pinhole test equipment.   The resin-coated pinhole testing apparatus for resin-coated steel materials according to any one of claims 1 to 3, wherein the ground plate is slidable along the length of the surface of the resin-coated steel material.   The resin-coated pinhole test apparatus for a resin-coated steel material according to claim 4, wherein an inner surface of the ground plate that is in contact with the surface of the resin-coated steel material is lubricated.   A method for testing the presence or absence of a resin-coated pinhole in a resin-coated steel material, wherein the surface of the resin-coated steel material is covered with a ground plate serving as an indirect ground, and the resin-coated steel material is different from the covering position of the ground plate The detection electrode is applied to the surface of the metal plate, and the required voltage is applied between the ground plate and the detection electrode. The detection electrode is slid on the surface of the resin-coated steel material. A resin-coated pinhole test method for a resin-coated steel material in which, when an electric current is generated during this period, the resin-coated pinhole is located at the sliding position of the detection electrode.   The detection electrode has a semi-annular shape, and the pinhole detection of the semi-circular surface of the surface of the resin-coated steel material is performed by the forward sliding in the length direction of the surface of the resin-coated steel material of the detection electrode. The resin-coated pinhole test method for a resin-coated steel material according to claim 6, wherein pinhole detection on the opposite half circumferential surface is performed.   The resin-coated pinhole test method for a resin-coated steel material according to claim 6 or 7, wherein the resin-coated steel material is an external cable.   9. The resin-coated steel material according to claim 8, wherein the outer cable is a PC steel material in which a plurality of stranded wires obtained by coating a stranded wire of a steel element wire with an epoxy resin are further twisted and the stranded wire coated with the resin is exposed. Resin-coated pinhole test method.   The resin-coated pinhole test method for a resin-coated steel material according to any one of claims 6 to 9, wherein the ground position is changed by sliding the surface of the resin-coated steel material in the length direction of the ground plate.   The resin-coated pinhole test method for a resin-coated steel material according to claim 10, wherein an inner surface of the ground contacting the surface of the resin-coated steel material is lubricated.

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