JP2018173354A - Rotary drive type hammering sound mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable correct inspection and diagnosis of the progress of corrosion to be performed over the entire conduit length by an elastic hammer driven to rotate.SOLUTION: A rotary drive type hammering sound mechanism 1 comprises a cage part 6 composed of a front hub 2 and a rear hub 3 towed by a tow cable 7 and a plurality of elastic bars 5 connected to be curved respectively in a circular-arc shape, a motor 4 fixed to one of the front hub 2 and the rear hub 3, a hummer rotation part 10 driven by the motor 4 and rotated relative to the cage part 6, and an elastic hammer 11 mounted on the hammer rotation part 10 and having a hammering sound part 11a on the tip end. When the cage part 6 is inserted into the conduit, the centering is performed by causing the tip end of the elastic bar 5 to press against the inner wall of the conduit. The inner wall of the conduit is hammered with the next-coming elastic bar 5 by an elastic force accumulated when a hammering sound part 11a of the elastic hammer 11 climbs over the elastic bar 5 by the rotation of the hammer rotation part 10, and the hammering is performed.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a rotary drive sounding mechanism used for, for example, pipe inspection in a chemical plant.

In chemical plants and the like, many pipes are laid in the facility, and if a leakage accident occurs, a serious situation such as fire or generation of harmful gases may occur.
In particular, the progress of corrosion cannot be confirmed by visual inspection of corrosion inside the pipe and external pipe corrosion (CUI) under the heat insulating material.
For this reason, conventionally, an inspection by an AE method (acoustic emission) and an inspection performed by inserting an inspection unit such as a CCD camera unit or an eddy current flaw detection unit into the pipe are employed.

Patent Document 1 describes a pipe inspection apparatus in which a CCD camera unit and an eddy current flaw detection unit are mounted on a connecting vehicle for inspection.
Further, Patent Document 2 describes a pipe inspection mechanism in which cables having different rigidity are connected in multiple stages to a rotary drive unit connected to an inspection apparatus head.

JP 2005-241474 A JP-A-11-125385

However, in the pipe inspection by the AE method, not only the equipment is expensive, but the installation is complicated, and there is a possibility that the inspection accuracy is deteriorated due to the influence of electromagnetic noise.
Also, the piping inspection apparatus disclosed in Patent Documents 1 and 2 has a complicated mechanism, especially in a bent thin tube or the like, the inside of the pipe cannot be smoothly moved, and the inspection apparatus is locked at a large bending angle, There is a problem that the inspection becomes impossible, and further, the removal itself becomes impossible.

  Accordingly, an object of the present invention is to allow a smooth passage by bending flexibly in accordance with the shape of the inside of the pipe, and the degree of corrosion progression over the entire pipeline length by an elastic hammer that is rotationally driven by a motor. It is to enable accurate inspection and diagnosis.

  In order to solve this problem, in the rotational drive sounding mechanism of the present invention, the front hub, the rear hub, and both ends that are pulled by the traction cable are connected to both hubs, and are arranged at regular intervals in the circumferential direction. And a cage portion composed of a plurality of elastic bars connected so as to be curved in an arc shape, a motor fixed to one of the front hub and the rear boss, and driven by the motor to be rotated with respect to the cage portion. A hammer rotating part and an elastic hammer attached to the hammer rotating part and provided with a sounding part at the tip. When the cage part is inserted into the pipe, the top of the elastic bar is pressed against the pipe inner wall. Thus, the elastic bar performs centering so that the central axis of the hammer rotating part coincides with the central axis of the pipe, and the hammer hammering part rotates the sounding part of the elastic hammer. By the elastic force stored in overcoming bar, beating the pipe inner wall between its subsequent elastic bar, and so that knocking sound.

  According to the present invention, the cage portion is flexibly bent according to the shape of the inside of the pipe, thereby enabling a smooth passage and generating an impact sound periodically by an elastic hammer that is rotationally driven by a motor. By acoustically analyzing this hitting sound, it is possible to reduce the size and weight of the pipe inspection device and reduce the cost, and even if it is a narrow tube with a bent portion, the progress of corrosion over the entire pipe length, etc. Accurate examination and diagnosis can be performed.

FIG. 1 is a diagram illustrating the overall configuration of the embodiment. FIG. 2 is a view of the front hub 2 as viewed from the front side in the pulling direction. FIG. 3 is a diagram illustrating the behavior of the cage portion 6 when passing through a pipe bent at a right angle. FIG. 4 is a diagram illustrating a state in which a dent is generated in the elastic bar 5 at a pipe right-angled bent portion. FIG. 5 is a view showing a modification in which the length of the elastic bar 5 is variable. FIG. 6 is a view showing a modification in which a centering mechanism and a microphone pop noise reduction cage are provided before and after the sound generation mechanism 1. FIG. 7 is a system diagram of a pipe inspection apparatus using this embodiment. FIG. 8 is a diagram showing a corrosion simulation pipe used in the experiment. FIG. 9 is a diagram illustrating a procedure of acoustic analysis of the hitting sound obtained by the hitting sound generation mechanism 1. FIG. 10 is a diagram showing a result of acoustic analysis.

  Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention. A sound generation mechanism 1 includes a front hub 2 provided at the front end in the pulling direction (left direction in FIG. 1) and a rear hub provided at the rear end in the pulling direction. 3, and an output shaft 4 a at the front, and a motor 4 that is fitted and supported on the rear hub 3 at the rear.
The front hub 2 and the rear hub 3 are connected by elastic bars 5 at equal angles in the circumferential direction, and in FIG. 1, 10 are provided every 36 °. These elastic bars 5 are inserted into the front hub 2 and the rear hub 3 obliquely in a state of being bent so as to form an arc, and by setting the length of the elastic bar 5, The force with which the elastic bar 5 tries to spread is balanced and curved between the front hub 2 and the rear hub 3 to form a cage portion 6 whose maximum diameter is several millimeters larger than the pipe diameter.

Thereby, in the inside of piping, the vertex of each elastic bar 5 which curves is uniformly pressed with the predetermined elastic force with respect to the inner wall of piping, and centering of cage part 6 is performed.
In this embodiment, the elastic bar 5 is formed of Insulok (registered trademark) used for a binding band and has a rectangular shape with a cross section of 1.7 mm (width) × 0.7 mm (thickness).

A traction cable 7 is connected to the front end of the front hub 2, and an electric winder installed outside the other end of the pipe pulls the sound generation mechanism 1 at a predetermined speed.
Further, behind the rear hub 3, two sound collecting microphones 9 directed vertically with respect to the normal line of the pipe are provided via a power / audio signal cable 8. The audio signal cable 8 extends and is connected to a DC power source and an analysis device described later.

  The frictional force acting between the apex of each elastic bar 5 and the inner wall of the pipe is small in the traction direction (the central axis direction of the sound generation mechanism 1) so that smooth traction by the traction cable 7 is possible, It is preferable to enlarge the cage portion 6 in the circumferential direction so that the cage portion 6 itself does not rotate due to a reaction caused by the rotation of the hammer rotating portion 10 described later. Therefore, after adjusting the elastic force to an optimum value, by providing a groove extending in the axial direction on the surface of each elastic bar 5, or in a cross-sectional shape orthogonal to the central axis of the sound generation mechanism 1, The rigidity in the normal direction may be reduced by reducing the thickness (0.7 mm in the above example), and the rigidity in the circumferential direction may be increased by increasing the width (1.7 mm in the above example).

A hammer rotating part 10 is attached to the output shaft 4a of the motor 4, and an elastic hammer 11 having a sounding part 11a such as a bearing at the tip is attached to the outer periphery thereof.
The elastic hammer 11 is formed of an elastic member, and the shape, length, and elastic coefficient of the elastic hammer 11 are selected so that the sounding portion 11a attached to the tip of the elastic hammer 11 presses the inner wall of the pipe with an appropriate pressing force. Yes.

FIG. 2 is a view of the front hub 2 as viewed from the front side in the pulling direction. In this embodiment, the elastic hammer 11 is rotated clockwise by the motor 4, and the elastic hammer 11 is convex toward the rotation direction. Curved in an arc.
When the hammer rotating portion 10 is rotated by the motor 4, the elastic hammer 11 attached to the outer periphery thereof is rotated. With this rotation, when the sound hitting portion 11a at the tip rides on one of the elastic bars 5, the elastic hammer 11 bends and accumulates elastic force. When the elastic bar 5 passes, the sounding portion 11a at the tip of the elastic hammer 11 is repelled toward the inner wall of the pipe by the accumulated elastic force, and at this time, sounding is generated. This hitting sound is generated every time the hitting part 11a passes through the next elastic bar 5.

FIG. 3 shows the behavior of the cage portion 6 when the sound generation mechanism 1 of the present embodiment passes through a pipe bent at a right angle. After the sound generation mechanism 1 approaches the right-angled bent portion as shown in (a), a part of the elastic bar 5 of the cage portion 6 contacts the inner peripheral end of the right-angled bent portion as shown in (b).
When pulled further, the elastic bar 5 bends starting from the contact portion between the elastic bar 5 and the inner peripheral end of the right-angled bent part, and as shown in FIG. Thus, a smooth passage is possible.

Depending on the inner diameter of the pipe and the size and shape of the cage part 6, as shown in FIG. 4, the elastic bar 5 may be dented on the inner peripheral end side of the right-angled bent part, and the frictional resistance increases rapidly. There is a risk that it may not be possible to pass the part.
Therefore, as shown in FIG. 5, the elastic bar 5 is divided into two parts, a front part 5a connected to the front hub 2 side and a rear part 5b connected to the rear hub 3, and provided at the tip of the rear part 5b. The tip of the front part 5a is inserted into the slide part 5c, and the elastic bar 5 can be expanded and contracted according to the contact pressure with the inner wall of the pipe. You may make it shrink.

  Further, as shown in FIG. 6, depending on the form of the piping, at least one of the front and rear of the hitting sound generating mechanism 1 is the same as the centering mechanism and microphone pop noise reduction similar to the cage structure of the hitting sound generating mechanism 1. By connecting a ball-shaped or conical aligning mechanism or radial brush with the same diameter as the cage and piping inner diameter, the pitching of the hitting sound generating mechanism 1 generated during towing and noise other than hitting sound can be prevented and reliably It is also possible to make a simple hitting sound.

  The sound generated by the sound generation mechanism 1 is measured by the sound collecting microphone 9, and the sound signal is input to the analysis unit 12 via the power / audio signal cable 8 as shown in FIG. Based on the winding amount signal from the take-up machine 13, it is recorded in correspondence with the position of the pipe, subjected to acoustic analysis, and then output to the display / output device 14. A current for driving the elastic hammer 11 by the motor 4 is supplied from the DC power supply 15 via the power / audio signal cable 8.

An experiment using the hitting sound generation mechanism of this embodiment will be described. The sound generation mechanism uses six elastic bars 5 every 60 degrees, and the pipe is an iron pipe with an inner diameter of 25 mm, an outer diameter of 35 mm (thickness of 5 mm), a length of 150 cm, and a dyneema thread as a traction cable. Using.
As shown in FIG. 8, the steel pipe has an engraved depth of 1 mm and a length of 5 cm at a point 30 cm from the right end, and an engraved depth of 1.5 mm, 2 mm, and 2.5 mm with an interval of 20 cm thereafter. A cut-out part with a length of 5 cm was provided, and a cut-out part with a cut-in depth of 3 mm and a length of 5 cm was provided at a distance of 15 cm on the left side with a cut-in depth of 2.5 mm.

  5. The voltage of the motor 4 for driving the hammer rotating unit 10 is set to 10 V, and the pulling speed by the electric winder 13 is 3 cm / s (speed 2), 4 cm / s (speed 3), 5 cm / s (speed 4), The test was conducted twice at 5 cm / s (speed 5), 7.5 cm / s (speed 6), and 8.5 cm / s (speed 7).

FIG. 9 shows a procedure of acoustic analysis, in which a recorded hitting sound file is input and time / frequency conversion is performed. And the pipe reverberation frequency range was detected, the above-mentioned location was detected by statistical processing, and the result of state evaluation was output.
FIG. 10 shows the measurement results of these twelve times. From the left, the upper row shows the measurement results of two times each when the traction speed is 3 cm / s (speed 2) and 4 cm / s (speed 3). Shows the measurement results twice each from the left, when the traction speed is 5 cm / s (speed 4) and 6.5 cm / s (speed 5). The lower part shows the traction speed from the left, 7.5 cm / s. The measurement results are shown twice each when (speed 6) and 8.5 cm / s (speed 7).
From this result, it was confirmed that even when the traction speed was high, an abnormality could be detected for a cutting depth of 2 mm or more (corrosion of 40% or more with respect to a thickness of 5 mm).

  Various factors such as the pulling speed, the rotation speed of the hammer rotating part 10, the thickness of the elastic bar 5, and the material of the sounding part are considered to affect the measurement result. The shape, curvature, inner diameter, and material of the pipe It is necessary to select the best one according to the situation.

  As described above, according to the present invention, it is possible to reduce the size and weight of the pipe inspection device and reduce the cost, and even for a thin tube having a bent portion, it is possible to accurately measure the progress of corrosion over the entire pipe length. Therefore, it can be widely used as an inspection device for various pipes in chemical plants.

DESCRIPTION OF SYMBOLS 1 ... Sound generating mechanism 2 ... Front hub 3 ... Back hub 4 ... Motor 5 ... Elastic bar 6 ... Cage part 7 ... Traction cable 8 ... Power supply and sound Signal cable 9 ... Sound collecting microphone 10 ... Hammer rotating part 11 ... Elastic hammer 11a ... Sounding part 12 ... Analysis unit 13 ... Electric winder 14 ... Display / output device 15 ... DC power supply

Claims (3)

A front hub to be pulled by a tow cable, a rear hub, and a plurality of elastic bars having both ends connected to both hubs, arranged at regular intervals in the circumferential direction, and connected to be curved in an arc shape A cage portion comprising:
A motor fixed to one of the front hub and the rear boss, a hammer rotating portion driven by the motor and rotated relative to the cage portion;
It consists of an elastic hammer attached to the hammer rotating part and having a sounding part at the tip,
When the cage portion is inserted into the pipe, the top of the elastic bar is elastically pressed against the inner wall of the pipe so that each of the elastic bars matches the central axis of the hammer rotating portion with the central axis of the pipe. While performing centering,
Due to the rotation of the hammer rotating part, the resilient force stored when the sound hitting part of the elastic hammer gets over the elastic bar hits the inner wall of the pipe with the next elastic bar to make a hitting sound. A rotary drive sounding mechanism characterized by that.   Both ends of the elastic bar 5 are obliquely inserted into the front hub and the rear hub, respectively, and by setting the length of the elastic bar 5, each elastic bar 5 has a force to spread. The rotary drive according to claim 1, wherein the elastic bar is curved between the front hub 2 and the rear hub 3 to form the cage portion whose maximum diameter is slightly larger than the pipe diameter. Type sounding mechanism.   The elastic bar is divided into two parts, a front part connected to the front hub side and a rear part connected to the rear hub side. The rotational drive type sounding mechanism according to claim 1 or 2, wherein the elastic bar can be expanded and contracted accordingly.

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