JP2018059779A - Tightening torque measurement device and tightening torque measurement method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a torque measurement device capable of measuring tightening torque between a pipe which has been already arranged and a joint.SOLUTION: A tightening torque measurement device for measuring tightening torque between a pipe and a joint includes: a stress measurement part for measuring stress on a screw part of the joint, which is tightened after the pipe is inserted; and a tightening torque calculation part for calculating the tightening torque from the stress measured by the stress measurement part on the basis of the relation between the pre-obtained stress on the screw part and the tightening torque.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a tightening torque measuring device and a tightening torque measuring method.

  Gas pipes piped to supply gas to various places are connected by joints. The gas pipe and the joint are connected, for example, by inserting and tightening the end of the gas pipe having the male thread groove on the outer peripheral surface into the thread part of the joint having the female thread groove formed on the inner peripheral surface. Is done.

  In the above-described configuration, gas may leak from the connection portion between the gas pipe and the joint due to poor connection between the gas pipe and the joint, deterioration over time of the connection portion between the gas pipe and the joint, or the like. In order to prevent such gas leakage, it is necessary to periodically inspect the connection portion between the gas pipe and the joint.

  As a method for inspecting a connection portion between a gas pipe and a joint, there is known a nondestructive inspection method for a pipe joint portion for inspecting damage generated in a pipe end portion by tightening the joint using an ultrasonic probe (for example, , See Patent Document 1).

Japanese Patent Laid-Open No. 2003-194783

  Although it is possible to inspect the pipe end for damage by the method in Patent Document 1, in order to inspect the connection state between the gas pipe and the joint, it is necessary to measure the tightening torque between the gas pipe and the joint. The tightening torque between the gas pipe and the joint can be measured using a torque wrench at the time of piping work, but it is actually difficult to measure the existing pipe because it is necessary to extract the pipe.

  This invention is made | formed in view of the above, Comprising: It aims at providing the torque measuring apparatus which can measure the fastening torque of the pipe and pipe already piped.

  According to one aspect of the present invention, there is provided a tightening torque measuring device that measures a tightening torque between a pipe and a joint, and a stress measuring unit that measures a stress of a thread portion of the joint that is inserted and tightened. A tightening torque calculation unit that calculates a tightening torque from the stress measured by the stress measurement unit based on the relationship between the stress of the screw part and the tightening torque that is obtained in advance.

  According to the embodiment of the present invention, a torque measuring device capable of measuring a tightening torque between a pipe already piped and a joint is provided.

It is a figure which illustrates schematic structure of the tightening torque measuring apparatus in embodiment. It is a figure explaining the connection structure of a gas pipe and a coupling. It is a figure which illustrates the stress measurement location in an embodiment. It is a figure which illustrates the relationship between the tightening torque and stress in embodiment.

  Hereinafter, embodiments for carrying out the invention will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and redundant description may be omitted.

  FIG. 1 is a diagram illustrating a schematic configuration of a tightening torque measuring device 100 according to the embodiment.

  As shown in FIG. 1, the tightening torque measuring device 100 includes a stress measuring unit 110 and a torque measuring unit 120 and measures the tightening torque between the gas pipe 10 and the joint 20.

  The stress measurement unit 110 measures the stress of the joint 20 by, for example, an X-ray stress measurement method that measures the stress of the surface layer portion of the polycrystalline material using X-ray diffraction, and transmits the measurement result to the torque measurement unit 120. To do. The stress measurement unit 110 may measure the stress of the joint 20 by a different method such as a neutron stress measurement method or a magnetostrictive stress measurement method.

  The torque measurement unit 120 includes a tightening torque calculation unit 121 and a storage unit 122. The torque measurement unit 120 includes, for example, a CPU, a ROM, a RAM, and the like, and functions of each unit are realized by a program executed by the CPU and a memory such as a ROM.

  The tightening torque calculation unit 121 calculates the tightening torque between the gas pipe 10 and the joint 20 from the stress of the joint 20 measured by the stress measurement unit 110. The storage unit 122 stores various data used for calculation of the tightening torque by the tightening torque calculation unit 121. A method for calculating the tightening torque by the tightening torque calculating unit 121 will be described later.

  FIG. 2 is a diagram illustrating a connection structure between the gas pipe 10 and the joint 20.

  As shown in FIG. 2, the gas pipe 10 has a connection portion 11 having an external thread groove on the outer peripheral surface at the end. The connecting portion 11 has a tapered shape with a smaller outer diameter toward the tip side. Further, the joint 20 has a threaded portion 21 having an internal thread groove on the inner peripheral surface at the end. The inner peripheral surface of the threaded portion 21 has a tapered shape with a larger inner diameter toward the opening end side.

  The gas pipe 10 is connected to the joint 20 by the connection portion 11 being inserted into the screw portion 21 of the joint 20 and being rotated in the direction of the arrow shown in FIG. Is done. When the gas pipe 10 is fastened to the joint 20, a circumferential compressive stress or tensile stress corresponding to the fastening torque is generated in the threaded portion 21 of the joint 20.

  Therefore, by obtaining the relationship between the tightening torque between the gas pipe 10 and the joint 20 and the stress at the threaded portion 21 of the joint 20 in advance, the tightening torque can be obtained from the stress measurement result at the threaded portion 21 of the joint 20. it can.

  In this embodiment, using a plurality of samples (a set of the gas pipe 10 and the joint 20), the stress is measured by changing the tightening torque at two measurement positions A and B shown in FIGS. The relationship between torque and stress was obtained.

  FIG. 4 is a diagram illustrating the relationship between the tightening torque and the stress in the embodiment. FIG. 4A shows stress measurement results at measurement positions A of samples 1 to 3. FIG. 4B shows a stress measurement result at the measurement position B of Samples 1 to 3.

  In the graph shown in FIG. 4, the horizontal axis represents the tightening torque (N · m), and the vertical axis represents the circumferential stress (MPa) in the threaded portion 21 of the joint 20. In the graph shown in FIG. 4, a stress of 0 (zero) or more is a tensile stress, and a stress of less than 0 (zero) is a compressive stress. 4A and 4B show the results of measuring the stress in samples 1 to 3 by changing the tightening torque from 0 N · m to 300 N · m at intervals of about 50 N · m. ing.

  As shown in FIGS. 4A and 4B, from the stress measurement results of samples 1 to 3, the tightening torque and the stress at the threaded portion 21 of the joint 20 are proportional to each other as indicated by the solid line in each graph. It can be seen that

  In the storage unit 122 of the torque measuring unit 120 in the present embodiment, the tightening measured by the stress measuring unit 110 using a plurality of samples (gas pipe and joint) having the same outer diameter and shape as the existing pipe for measuring the tightening torque. A relational expression between torque and stress is stored.

  The tightening torque calculation unit 121 of the torque measurement unit 120 is based on the stress measurement result in the threaded portion 21 of the joint 20 to be measured by the stress measurement unit 110 based on the relational expression stored in the storage unit 122 and the gas pipe 10. A tightening torque with the joint 20 is calculated.

  In this way, by obtaining the relationship between the tightening torque and the stress in advance by using the sample by the stress measuring unit 110, the stress measurement results at the measurement positions A and B of the joint 20 in the existing pipe can be obtained from the gas pipe 10 and The tightening torque with the joint 20 can be calculated.

  According to the tightening torque measuring device 100 in the present embodiment, the tightening torque between the gas pipe 10 and the joint 20 can be measured by measuring the stress of the threaded portion 21 of the joint 20 without extracting the existing pipe. . Further, the tightening torque measuring apparatus 100 similarly measures the tightening torque between the gas pipe 10 and the joint 20 by measuring the stress of the threaded portion 21 of the joint 20 even in piping work in a narrow place where a torque wrench cannot be used. be able to.

  As described above, according to the tightening torque measuring apparatus 100, the tightening torque between the gas pipe 10 and the joint 20 that have already been piped can be measured, and the connection state between the gas pipe 10 and the joint 20 can be inspected. It can be done easily.

  Accordingly, the connection state between the gas pipe 10 and the joint 20 can be inspected based on the measurement result of the tightening torque, and the gas leakage from the connection portion between the gas pipe 10 and the joint 20 can be suppressed. For example, by tightening the gas pipe 10 and the joint 20 so that the tightening torque is within a predetermined range, the connection state between the gas pipe 10 and the joint 20 can be kept normal, and the occurrence of gas leakage can be suppressed.

  In addition, when measuring the stress of the joint 20 by the X-ray stress measurement method like the stress measurement unit 110 in the present embodiment, it is preferable to polish the stress measurement position of the joint 20 using, for example, sandpaper. . Further, the tightening torque measuring device 100 may include a polishing unit that polishes the stress measurement position of the joint 20. If the crystal grains at the measurement position are large, the measurement accuracy may be lowered. However, by polishing and refining the crystal grains at the measurement position of the joint 20, it is possible to improve the stress measurement precision. For this reason, when calculating | requiring the relationship between fastening torque and stress using a sample, and measuring the stress of the joint 20, it is preferable to grind the measurement position of the joint 20.

  Further, the outer diameter of the gas pipe for measuring the tightening torque, the shape of the joint, and the like are not limited. Gas pipes and fittings of any outer diameter and shape can be obtained in advance by determining the relationship between the tightening torque and stress using the same outer diameter and shape of gas pipes and fittings as the gas pipes and fittings for measuring the tightening torque. The tightening torque can be measured.

  Further, the storage unit 122 of the torque measuring unit 120 may store the relationship between the tightening torque and the stress in various combinations of gas pipes having different outer diameters and joints having different shapes. As described above, the relationship between the tightening torque and the stress in various combinations is stored in the storage unit 122, so that the tightening torque between the gas pipe and the joint having various configurations can be measured.

  Moreover, although the case where the fastening torque of a gas pipe and a coupling was measured was illustrated in the above-mentioned embodiment, the fastening torque of different pipes and joints, such as a water pipe, can be measured similarly.

  The tightening torque measuring device and the tightening torque measuring method according to the embodiment have been described above, but the present invention is not limited to the above embodiment, and various modifications and improvements can be made within the scope of the present invention.

DESCRIPTION OF SYMBOLS 10 Gas pipe 11 Connection part 20 Joint 21 Thread part 100 Tightening torque measuring apparatus 110 Stress measuring part 120 Torque measuring part 121 Tightening torque calculating part 122 Storage part

Claims (4)

A tightening torque measuring device for measuring a tightening torque between a pipe and a joint,
A stress measuring unit for measuring the stress of the threaded portion of the joint into which the tube is inserted and tightened;
A tightening torque calculating unit that calculates a tightening torque from the stress measured by the stress measuring unit based on a relationship between the stress of the screw part and the tightening torque obtained in advance. measuring device. A polishing portion for polishing a portion for measuring stress in the thread portion;
The tightening torque measuring device according to claim 1, wherein the stress measuring unit measures the stress of the screw portion using X-rays. A tightening torque measuring method for measuring a tightening torque between a pipe and a joint,
A stress measuring step for measuring a stress of a thread portion of the joint into which the tube is inserted and tightened;
A tightening torque calculating step of calculating a tightening torque from the stress measured in the stress measurement step based on a relationship between the stress of the screw portion and the tightening torque obtained in advance. Measuring method. A polishing step of polishing a portion for measuring stress in the thread portion;
The tightening torque measuring method according to claim 3, wherein the stress measuring step measures the stress of the screw portion using X-rays.

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