JPH0979951A - Thin-tube sampling device and its using method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently and surely collect the material test sample of a thin heat exchanger tube through the tube. SOLUTION: A thin-tube sampling device is provided with a guide hose 21 and an electric discharge machining head 23 which is fitted to the front end of the hose 21 and provided with a binding wire connecting section. The head 23 is incorporated with a gate type machining electrode 27 which gets out of and in the head 23 and a tension wire driving mechanism extended in the hose 21 is connected to the electrode 27 so that the mechanism can be driven. In addition, a leaf spring 39 with an adhesive tape 37 is elastically fitted to the head 23 and a lead-in wire 41 extended in the hose 21 is connected to one end of the spring 39. The spring 39 is positioned in the pivotally moving locus of the electrode 27 so that the spring 39 can be faced to the collected sample section of a heat exchanger tube 19 and selectively protruded from the locus.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for collecting a sample for inspecting a material of a thin tube, and particularly to a sample of a thin heat transfer tube which is difficult to access from the outside such as a U-shaped heat transfer tube of a heat exchanger. Related to the device to be collected from.

[0002]

2. Description of the Related Art In heat exchangers, a large number of thin heat transfer tubes forming a heat transfer tube bundle are often used. When it is necessary to check the presence or absence of such deterioration of the material of the heat transfer tube, it is recommended to use a reliable method of sampling and inspecting the sample. In this case, when the target heat transfer tube to be inspected is located at the center of the tube bundle, it is difficult to access it from the outside, so special measures are required. Incidentally, if the target heat transfer tube to be inspected is accessed from the outside, the other heat transfer tube on the outside must be cut off, resulting in a decrease in heat exchange capacity and the cost of repairing it, which is a heavy burden. Become. As an example of a heat exchanger that requires such inspection,
There is a steam generator for a pressurized water reactor.

An apparatus shown in FIG. 4, for example, has been proposed as an apparatus for collecting a sample of the heat transfer tube of the above steam generator from the inside of the tube. To briefly explain this structure, an electric discharge machining head 2 surrounded by a cap 5 is attached to the tip of a long guide hose 3 inserted into a thin heat transfer tube 1. A centering brush 11 is rotatably attached to the tip of the electric discharge machining head 2 via a guide 9 and a bearing 7. A machining electrode 15 pivoted by a drive shaft 13 penetrating through the guide hose 3 is provided in the electric discharge machining head 2, and a machining current is supplied to the machining electrode 2 by an energizing brush 17. In order to collect a sample using the apparatus as described above, the electric discharge machining head 2 is inserted into the heat transfer tube 1 with the rotatable centering brush 11 as a guide. After reaching the sampling position, the machining electrode 15 that was pulled in at the time of insertion is rotated clockwise by the drive shaft 13 to press it against the inner surface of the heat transfer tube 1, and electric discharge machining is performed by the current supplied through the energizing brush 17. Then, the target part is cut and a sample is collected.

[0004]

The sampling device as described above has the following problems. That is, the centering brush has a gap formed between it and the inner surface of the heat transfer tube in order to enhance the insertability, and further has flexibility in the longitudinal direction. Therefore, when electric discharge machining is performed by bringing the machining electrode close to the inner surface of the heat transfer tube, a relative positional deviation occurs between the two, which makes stable machining difficult. Further, in order to collect a sample from the heat transfer tube, it is necessary to machine and cut four rounds of the target site. Therefore, in the above-mentioned device, the electric discharge machining head 2 is swung and moved back and forth to shift the position of the machining electrode, It was collected and the operation was complicated. Further, during the electric discharge machining, since the machining fluid is being jetted and supplied, the sample that has been cut into pieces at a break may fall outside the heat transfer tube, which makes it difficult to obtain a stable sample. Therefore, an object of the present invention is to perform stable electric discharge machining to efficiently perform cutting when collecting a sample from a thin tube through the inside of the tube, and to reliably collect the cut and separated sample outside the thin tube without dropping it. Is.

[0005]

In order to solve the above-mentioned problems, a thin tube sampling device according to the present invention is provided with a flexible hollow rod and a flexible wire attached to the distal end of the flexible hollow rod and a binding wire at the distal end. An electric discharge machining head having a connecting portion, the electric discharge machining head being pivotally mounted inside, and including a gate-shaped machining electrode that is pivoted to appear and disappear outside the electric discharge machining head, and inside the flexible hollow rod. The tip of the extended tension wire drive mechanism is connected to the processing electrode. More preferably, the electric discharge machining head also has an adhesive holding plate that is located in the pivotal locus of the machining electrode, faces the sampled portion of the thin tube, and is elastically displaceable. , A pulling wire extending in the flexible hollow rod is connected to one end of the adhesive holding plate, and when the pulling wire is released, the adhesive holding plate projects from the electric discharge machining head and can be bonded to a sample sample portion. Has become.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings. In FIG. 1, a guide hose 21 which is a flexible hollow rod is inserted into a heat transfer tube 19 shown as a bent thin tube. The following electric discharge machining head 23 is attached to the tip of the guide hose 21. The tip of the electric discharge machining head 23 is surrounded by an insulating cap 25, and has a gate-shaped or inverted U-shaped machining electrode 27.
Is provided so as to be pivotable, and a tension wire 29 is wound around the pivot shaft of the machining electrode 27. The tension wire 29 passes through the main body of the electric discharge machining head 23 and further extends through the guide hose 21, and constitutes a tension wire drive mechanism together with a guide pulley appropriately arranged. Then, if one of the operation ends on the outside of the tension wire 29 is pulled, the machining electrode 27 is rotated clockwise as shown by the chain double-dashed line, and if the other end is pulled, it is rotated counterclockwise. In this way, the cap 2 can be supplied with the machining current regardless of the position of the pivoting machining electrode 27.
An energizing brush 31 is provided on the inner side of 5, and a power supply line (not shown) connected thereto extends through the main body of the electric discharge machining head 23 and the guide hose 21 to communicate with a power source (not shown). The front shape of the inverted U-shaped processing electrode 27 is shown in FIG.

A connection button 33 is formed so as to project at the extreme end of the electric discharge machining head 23, and one end of a tight fixing wire 35 extending to the other end inside the heat transfer tube 19 is connected to this. Since the fixed wire 35 is passed through the target heat transfer tube 19 from the other end and is connected before the electric discharge machining head 23 is inserted, an insertion guide member or the like conventionally required is not required.
Further, an elastic adhesive holding plate or a leaf spring 39 having an adhesive tape 37 is located in the pivotal locus of the processing electrode 27.
The outer shape of the leaf spring 39 is designed to fit inside the inverted U-shaped machining electrode 27 shown in FIG. 2, and even if the adhesive tape 37 is brought into contact with the heat transfer tube 19, It does not hinder the rotation of the electrode 27. Such contact of the adhesive tape 37 is performed by operating the pulling wire 41 which is connected to one end of the leaf spring 39 and extends through the electric discharge machining head 23 and the guide hose 21.

A procedure for collecting (cutting and collecting) a sample of the heat transfer tube using the sample collecting device having the above-described structure will be described. Referring to FIG. 3, the tip of the fixed wire 35 extending from the other end of the heat transfer tube 19 is connected to the connection button 33,
The electric discharge machining head 23 is inserted into the heat transfer tube 19 while being held by the guide hose 21. At that time, the tension wire driving mechanism holds the machining electrode 27 in the neutral position and holds the machining electrode 27 in the drawing position shown in the drawing. The leaf spring 39 on which the adhesive tape 37 is stretched pulls the pull-in wire 41 and holds it at the pull-in position (FIG. 1). And electric discharge machining head 2
When the wire 3 reaches a predetermined position in the heat transfer tube 19, the fixing wire 35 is tensioned (tightened) as shown in the figure to fix it. Next, when the pull-in wire 41 is loosened, the leaf spring 39 is elastically restored, and the double-sided adhesive tape 37 stretched on the surface as shown in the figure is adhered to the inner surface of the heat transfer tube 19 at the target position. Then, one of the operation ends of the tension wire 29 of the tension wire drive mechanism is pulled, and the machining electrode 27 is pressed against and brought into contact with the inner surface of the heat transfer tube 19 so as to pivot so as to draw a locus shown by an imaginary line. At the same time, power is supplied to the machining electrode 27 via the power supply line and the current-carrying brush 31, and a machining liquid (pure water) not shown is supplied to the machining site. Then, a discharge phenomenon occurs between the machining electrode 27 and the portion of the heat transfer tube 19 facing the processing electrode 27, and the heat transfer tube material located at the contact portion is lost. Therefore, if the above-described electric discharge machining is continued, the material of the heat transfer tube 19 on the pivotal locus of the machining electrode 27 is lost, and the groove is formed, so that the portion surrounded by the groove can be separated as a sample.

Since the above-mentioned sample which has been cut and separated is adhered and held by the adhesive tape 37 as described above, when the pulling wire 41 is pulled again, the sample enters the cap 25. The pivoting angle of the machining electrode 27 or the completion of machining can be known by the amount of pull-in of the operation end of the tension wire 29. Therefore, when the electric discharge machining is completed, the other end of the tension wire 29 is pulled to return the machining electrode 27 to the original position. When the guide hose 21 is pulled out from the heat transfer tube 19 while the pull-in wire 41 is pulled and the separated sample is held in the cap 25, the electric discharge machining head 23 comes out of the heat transfer tube 19 and is held therein. The sample is collected.

[0010]

As described above, according to the present invention, the electric discharge machining head having the gate-shaped machining electrode is fixed by the binding wire, and four rounds of the sample to be sampled are cut by one pivoting operation of the machining electrode. Therefore, the sample of the thin tube can be stably collected from the inside of the tube. Further, according to the present invention, since the collected sample portion is bonded and held in advance by the adhesive holding plate, the cut and separated sample can be prevented from falling off and the sample can be reliably collected and collected.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view showing a main part of an embodiment of the present invention.

FIG. 2 is a view seen from the direction of arrow II in FIG.

FIG. 3 is a partial cross-sectional view showing a usage state of the embodiment.

FIG. 4 is a vertical cross-sectional view showing an example of a conventional device.

[Explanation of symbols]

 21 Guide Hose 23 Electric Discharge Machining Head 27 Machining Electrode 29 Tension Wire 35 Fixed Wire 37 Adhesive Tape 39 Leaf Spring 41 Pulling Wire

Claims (4)

[Claims] 1. A flexible hollow rod and an electric discharge machining head attached to the tip of the flexible hollow rod and provided with a binding wire connecting portion at the tip, the electric discharge machining head being pivotally mounted inside. The electric discharge machining head has a gate-shaped machining electrode that is pivoted and protrudes and retracts outside the electric discharge machining head, and the tip of a tension wire drive mechanism extending in the flexible hollow rod is connected to the machining electrode. A device for sampling a thin tube, which is capable of pivoting. 2. The electric discharge machining head further comprises an adhesive holding plate elastically attached, and a pulling wire extending in the flexible hollow rod is connected to one end of the adhesive holding plate.
2. The sample collecting device for a thin tube according to claim 1, wherein the adhesive holding plate is located in a pivotal locus of the processing electrode, faces the sampled portion, and selectively protrudes out of the pivotal locus. 3. The flexible hollow rod and the electric discharge machining head are inserted into a thin tube, the electric discharge machining head is pulled and fixed by a binding wire, and the portal machining electrode is pivoted to move the sample portion to the thin tube body. The method for using the capillary tube sampling device according to claim 1, wherein the sampling device is cut and separated from the sample. 4. The flexible hollow rod and the electric discharge machining head are inserted into a bent thin tube, the electric discharge machining head is pulled and fixed by a binding wire, and the adhesive holding plate is projected from the electric discharge machining head to a sampling sample portion. 3. The method of using a capillary tube sampler according to claim 2, wherein the capillary tube is bonded and the gate-shaped processing electrode is pivoted while maintaining the bonded state to cut and separate the sample portion from the capillary body.