JP6800448B2 - Rotational drive type tapping mechanism - Google Patents

Description

The present invention relates to, for example, a rotary drive type tapping mechanism used for piping inspection in a chemical plant.

In chemical plants, many pipes are laid in the facility, and if a leak accident should occur, it may cause a serious situation such as fire or generation of harmful gas.
In particular, corrosion inside the pipe and corrosion on the outer surface of the pipe under the heat insulating material (CUI) cannot be confirmed by visual inspection.
For this reason, conventionally, inspections by the AE method (acoustic emission) and inspections performed by inserting an inspection unit such as a CCD camera unit or an eddy current flaw detection unit into a pipe have been adopted.

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

Japanese Unexamined Patent Publication No. 2005-241474 JP-A-11-125385

However, in the piping inspection by the AE method, not only the equipment is expensive, but also the installation is complicated, and the inspection accuracy may be deteriorated due to the influence of electromagnetic noise.
Further, the piping inspection device disclosed in Patent Documents 1 and 2 also has a complicated mechanism, and particularly in a bent thin pipe or the like, the inside of the pipe cannot be moved smoothly, and the inspection device locks in a place where the bending angle is large. There was a problem that the inspection became impossible and that the removal itself became impossible.

Therefore, an object of the present invention is to enable smooth passage by flexibly bending according to the shape of the inside of the pipe, and to use an elastic hammer rotationally driven by a motor to promote the degree of corrosion over the entire length of the pipe. It is to enable accurate inspection and diagnosis.

In order to solve this problem, in the rotary drive type tapping mechanism of the present invention, the front hub and the rear hub towed by the tow cable are connected to both hubs at both ends and arranged at regular intervals in the circumferential direction. A cage portion consisting of a plurality of elastic bars connected so as to be curved in an arc shape, a motor fixed to one of a front hub and a rear boss, and driven by this motor and rotated with respect to the cage portion. It consists of an elastic hammer that is attached to the rotating part of the hammer and has a tapping sound part at the tip. When the cage part is inserted into the pipe, the apex of the elastic bar is compressed against the inner wall of the pipe. As a result, the elastic bar centers the central axis of the rotating part of the hammer so that it coincides with the central axis of the pipe, and the rotation of the rotating part of the hammer causes the elastic hammer's striking part to get over the elastic bar. The force was used to hit the inner wall of the pipe with the next elastic bar to make a sound.

According to the present invention, the cage portion flexibly bends according to the shape inside the pipe to enable smooth passage, and the elastic hammer rotationally driven by the motor periodically generates a tapping sound. By acoustically analyzing this tapping sound, it is possible to reduce the size and weight of the piping inspection device and reduce the cost, and even for thin pipes with bent parts, the degree of corrosion progress over the entire length of the pipe, etc. Can perform accurate inspection and diagnosis.

FIG. 1 is a diagram showing an overall configuration of an embodiment. FIG. 2 is a view of the front hub 2 as viewed from the front side in the towing direction. FIG. 3 is a diagram showing the behavior of the cage portion 6 when passing through a pipe bent at a right angle. FIG. 4 is a diagram showing how a dent is generated in the elastic bar 5 at the right-angled bent portion of the pipe. FIG. 5 is a diagram showing a modified example in which the length of the elastic bar 5 is variable. FIG. 6 is a diagram showing a modified example in which a centering mechanism and a cage for reducing microphone pop noise are provided before and after the tapping sound generation mechanism 1. FIG. 7 is a system diagram of a piping inspection device using this embodiment. FIG. 8 is a diagram showing a corrosion simulation pipe used in the experiment. FIG. 9 is a diagram showing a procedure for acoustic analysis of the tapping sound obtained by the tapping sound generation mechanism 1. FIG. 10 is a diagram showing the results of acoustic analysis.

Hereinafter, examples of the present invention will be described with reference to the drawings.

FIG. 1 shows an embodiment of the present invention, in which the tapping sound generation mechanism 1 includes a front hub 2 provided at the front end in the towing direction (left direction in FIG. 1) and a rear hub provided at the rear end in the towing direction. 3 and a motor 4 having an output shaft 4a in the front and being fitted and supported by a rear hub 3 in 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 bars are provided every 36 °. Both ends of these elastic bars 5 are obliquely inserted into the front hub 2 and the rear hub 3 in a state of being bent so as to form an arc. By setting the length of the elastic bars 5, each of these elastic bars 5 is formed. The force of the elastic bar 5 to spread is balanced, and the front hub 2 and the rear hub 3 are curved to form a cage portion 6 having a maximum diameter of several millimeters larger than the pipe diameter.

As a result, inside the pipe, the apex of each curved elastic bar 5 is uniformly pressed against the inner wall of the pipe with a predetermined elastic force, and the cage portion 6 is centered.
In this embodiment, the elastic bar 5 is formed by an insulator (registered trademark) used for a binding band, and has a rectangular cross section of 1.7 mm (width) × 0.7 mm (thickness).

A tow 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 tapping sound generating mechanism 1 at a predetermined speed.
Further, behind the rear hub 3, two sound collecting microphones 9 are provided which are directed in the vertical direction with respect to the normal line of the piping via the power supply / audio signal cable 8, and behind the power supply / audio signal cable 8. -The audio signal cable 8 extends and is connected to a DC power supply and an analyzer 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 towing direction (the direction of the central axis of the tapping sound generation mechanism 1) so that the tow cable 7 can be smoothly towed. It is preferable to increase the size in the circumferential direction so that the cage portion 6 itself does not rotate due to the reaction caused by the rotation of the hammer rotating portion 10 described later. Therefore, after adjusting the elastic force to an optimum value, a groove extending in the axial direction is provided on the surface of each elastic bar 5, or in a cross-sectional shape orthogonal to the central axis of the tapping sound generation mechanism 1. It is preferable to reduce the rigidity in the normal direction by reducing the thickness (0.7 mm in the above example) and increase the rigidity in the circumferential direction by increasing the width (1.7 mm in the above example).

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

FIG. 2 is a view of the front hub 2 viewed from the front side in the traction direction. In this embodiment, the elastic hammer 11 is rotated clockwise by the motor 4, and the elastic hammer 11 is convex in the rotation direction. It is curved in an arc shape.
When the hammer rotating portion 10 is rotated by the motor 4, the elastic hammer 11 attached to the outer periphery thereof rotates. Along with this rotation, when the tapping 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 accumulated elastic force causes the tapping sound portion 11a at the tip of the elastic hammer 11 to be repelled toward the inner wall of the pipe, and at this time, a tapping sound is generated. This tapping sound is generated every time the tapping sound portion 11a passes through the next elastic bar 5.

FIG. 3 shows the behavior of the cage portion 6 when the tapping sound generation mechanism 1 of this embodiment passes through a pipe bent at a right angle. After the tapping sound generating mechanism 1 approaches the right-angled bent portion as shown in (a), a part of the elastic bar 5 of the cage portion 6 comes into contact with the inner peripheral end of the right-angled bent portion as shown in (b).
When further pulled, 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 portion, and as shown in (c), has a spherical shape together with the elastic bar 5 on the outer peripheral side of the right-angled bent portion. Therefore, smooth passage is possible.

Depending on the inner diameter of the pipe and the size and shape of the cage portion 6, as shown in FIG. 4, a dent is generated in the elastic bar 5 on the inner peripheral end side of the right-angled bent portion, and the frictional resistance rapidly increases. It may be impossible to pass through the part.
Therefore, as shown in FIG. 5, the elastic bar 5 is divided into a front portion 5a connected to the front hub 2 side and a rear portion 5b connected to the rear hub 3 side, and provided at the tip of the rear portion 5b. The tip of the front portion 5a is inserted into the sliding portion 5c so that the elastic bar 5 can be expanded and contracted according to the contact pressure with the inner wall of the pipe, and the elastic bar 5 on the inner peripheral side where the contact pressure increases when passing through the right-angled bending portion is provided. It may be made to shrink.

Further, as shown in FIG. 6, depending on the form of the piping, at least one of the front side and the rear side of the tapping sound generating mechanism 1 is for a centering mechanism similar to the cage structure of the tapping sound generating mechanism 1 and for reducing microphone pop noise. By connecting a ball-shaped or conical centering mechanism or radial brush with the same diameter as the cage and the inner diameter of the pipe, pitching of the tapping sound generation mechanism 1 generated during towing and noise other than tapping sound are prevented and surely. The tapping sound may be made.

The tapping sound generated by the tapping sound generation mechanism 1 is measured by the sound collecting microphone 9, and the audio signal is input to the analysis unit 12 via the power supply / audio signal cable 8 as shown in FIG. 7, and is electrically wound. Based on the take-up amount signal from the taker 13, it is recorded in correspondence with the position of the pipe, acoustic analysis is performed, and then it is output to the display / output device 14. The current for driving the elastic hammer 11 by the motor 4 is supplied from the DC power supply 15 via the power supply / audio signal cable 8.

An experiment using the tapping sound generation mechanism of this example will be described. The tapping sound generation mechanism uses six elastic bars 5 every 60 degrees, and the piping is an iron pipe with an inner diameter of 25 mm, an outer diameter of 35 mm (thickness 5 mm), and a length of 150 cm, and a Dyneema thread as a tow cable. Using.
As shown in FIG. 8, in the iron pipe, a carved portion having a carving depth of 1 mm and a length of 5 cm is provided at a point 30 cm from the right end at an interval of 20 cm below, and the carving depth is 1.5 mm, 2 mm, 2.5 mm. , A shaving portion having a length of 5 cm was provided, and a shaving portion having an engraving depth of 3 mm and a length of 5 cm was provided at an interval of 15 cm to the left of the engraving depth of 2.5 mm.

The voltage of the motor 4 for driving the hammer rotating portion 10 is 10 V, and the traction speed by the electric winder 13 is 3 cm / s (speed 2), 4 cm / s (speed 3), 5 cm / s (speed 4), 6. It was performed 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 tapping sound file is input and time / frequency conversion is performed. Then, the pipe echo frequency range was detected, the above points were detected by statistical processing, and the result of the state evaluation was output.
FIG. 10 shows the measurement results of these 12 times. From the left, the upper row shows the measurement results of 2 times each when the traction speed is 3 cm / s (speed 2) and 4 cm / s (speed 3). From the left, the measurement results are measured twice each when the traction speed is 5 cm / s (speed 4) and 6.5 cm / s (speed 5), and from the left, the traction speed is 7.5 cm / s. The measurement results are shown twice for each of (speed 6) and 8.5 cm / s (speed 7).
From this result, it was confirmed that an abnormality can be detected for a cutting depth of 2 mm or more (corrosion of 40% or more with respect to a wall thickness of 5 mm) even in a case where the traction speed is high.

It is considered that various factors such as the traction speed, the rotation speed of the hammer rotating portion 10, the thickness of the elastic bar 5, and the material of the tapping portion affect the measurement results, and the shape, curvature, inner diameter, and material of the pipe. It is necessary to select the most suitable one according to.

As described above, according to the present invention, it is possible to reduce the size and weight of the piping inspection device and the cost, and even for a thin pipe having a bent portion, the progress of corrosion and the like can be accurately measured over the entire length of the pipe. Since it can perform various inspections and diagnoses, it can be expected to be widely adopted as an inspection device for various pipes in chemical plants and the like.

1 ... Striking sound generation mechanism 2 ... Front hub 3 ... Rear hub 4 ... Motor 5 ... Elastic bar 6 ... Cage 7 ... Tow cable 8 ... Power supply / sound Signal cable 9 ... Sound collecting microphone 10 ... Hammer rotating part 11 ... Elastic hammer 11a ... Sound tapping part 12 ... Analysis unit 13 ... Electric winder 14 ... Display / output device 15 ... DC power supply

Claims (3)

A front hub towed by a tow cable, a rear hub, and a plurality of elastic bars whose ends are connected to each of the hubs, arranged at regular intervals in the circumferential direction, and connected so as to be curved in an arc shape. Cage part consisting of
A motor fixed to one of the front hub and the rear hub , a hammer rotating portion driven by the motor and rotated with respect to the cage portion,
It consists of an elastic hammer attached to the hammer rotating part and having a hammering part at the tip.
When the cage portion is inserted into the pipe, the apex of the elastic bar is repressed against the inner wall of the pipe so that each of the elastic bars coincides with the central axis of the hammer rotating portion with the central axis of the pipe. Centering and
Due to the rotation of the hammer rotating portion, the elastic force stored when the hitting portion of the elastic hammer gets over the elastic bar hits the inner wall of the pipe with the next elastic bar to make a tapping sound. Rotational drive type tapping mechanism characterized by the fact that Wherein and both end portions of the elastic bar is inserted obliquely to each of the rear hub and the front hub, by setting the length of the elastic bar, force, each of which attempts to spread the resilient bar to balance, said elastic bar is curved between the rear hub and the front hub, the maximum diameter according to claim 1, characterized in that to form the cage portion slightly larger than the diameter of the pipe Rotational drive type tapping mechanism. The elastic bar is divided into a front portion connected to the front hub side and a rear portion connected to the rear hub side, and the two are slidably connected to each other to reduce the contact pressure with the inner wall of the pipe. The rotary drive type tapping mechanism according to claim 1 or 2, wherein the elastic bar can be expanded and contracted accordingly.

Images