JP3782863B2 - Bellows type expansion joint - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a bellows type expansion joint.
[0002]
[Prior art]
In piping equipment, when stress is generated due to expansion and contraction of piping due to a temperature change or the like, the stress may cause the piping to break. For this reason, various types of expansion joints have been installed at the joints of pipes so as to absorb this stress.
In particular, bellows type expansion joints are widely used as expansion joints for piping of low-pressure steam, water, air, gas, etc. pipes, and are expanded and contracted in the longitudinal direction by bellows provided on the body part. The stress generated in the pipe can be absorbed.
[0003]
FIG. 3 is a side view showing a conventional bellows type expansion joint 31. In the figure, the upper half of the center line is shown in cross section.
In the figure, L ₀ indicates the inter-surface length of the bellows-type expansion joint, and L indicates the length of the bellows 32. In the figure, when the bellows 32 contracts by X mm in the axial direction (longitudinal direction), or conversely extends by X mm, the displacement of the bellows 32 is ± X mm. This displacement is caused by the expansion and contraction of the bellows 32 having a length L. In the figure, since the number of peaks of the bellows 32 is five, the displacement amount per peak is ± X / 5 mm, and the stress σ ₁ is generated when the bellows 32 is displaced ± X / 5 mm in the axial direction. The bellows-type expansion joint 31 is fatigued by repeating the generation of the stress σ ₁ and finally breaks. Hereinafter, the number of displacements is referred to as “displacement repetition number”, and the number of times the stress σ ₁ is generated is referred to as “stress repetition number”. Further, these are collectively referred to as “the number of repetitions”, and the number of repetitions until the bellows 32 breaks is N.
[0004]
When the bellows dimension is fixed, the number N of repetitions leading to the fracture can be calculated by a relational expression with the stress value. In general, the value of N is calculated, and the prescribed or allowable number of repetitions (hereinafter referred to as “life repetition number Nc”) is determined in consideration of the safety factor. Then, the number of repetitions per unit time (or day) is predicted, and the apparent lifetime or lifetime is set. The user of the bellows type expansion pipe joint plans the replacement time of the joint based on the set life days, and performs thorough maintenance management of the piping in which the bellows type expansion pipe joint is used.
[0005]
[Problems to be solved by the invention]
However, the setting of the replacement time of the conventional bellows-type expansion and contraction pipe joint is performed only by the apparent life days calculated before the start of use as described above. Therefore, if the apparent life days are not calculated before the start of use due to carelessness of the user, etc., and if the start time of use is not known, the remaining life of the bellows type expansion joint will be lost. Since it is unknown, there is a problem that proper replacement cannot be performed, and as a result, maintenance of the piping cannot be achieved.
[0006]
In addition, depending on the environment in which the bellows expansion / contraction pipe joint is installed, the number of repetitions per unit time that has been predicted in advance varies, and there is a large difference between the exact replacement time and the originally planned replacement time. There is a problem that it occurs.
[0007]
An object of the present invention is to provide a bellows type expansion joint that can solve the above problems and can easily grasp the replacement time.
[0008]
[Means for Solving the Problems]
The bellows type expansion joint of the present invention has the following characteristics.
(1) A bellows-type expansion / contraction pipe joint provided with detection means capable of detecting expansion / contraction of the bellows.
[0009]
(2) The bellows type expansion and contraction according to the above (1), which has an arithmetic unit capable of calculating the remaining life of the bellows type expansion joint from information relating to the expansion and contraction detected by the detection means, and a remaining life display unit for displaying the remaining life. Pipe fittings.
[0010]
[Action]
In the present invention, the bellows type expansion joint is provided with detection means for detecting expansion and contraction of the bellows. Therefore, the user can know the number of repetitions from such detection means even if the bellows-type expansion joint is in use, and can further manage the bellows-type expansion joint by the number of repetitions. it can. Thus, it is an idea which has not existed in the past to detect the expansion and contraction of the bellows and to manage the bellows-type expansion joint based on the number of repetitions.
[0011]
Further, in the bellows type expansion joint having the remaining life display device of the present invention, the user can repeat the number of repetitions until the replacement (hereinafter referred to as “remaining repetition number”) and the time remaining until the replacement (hereinafter “ It is possible to visually confirm the remaining life time) and the number of days left until the replacement (hereinafter referred to as “remaining life time”). Therefore, it is possible to easily grasp the replacement time of the bellows-type expansion joint, and to easily and quickly maintain the piping.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings.
FIG. 1 is a side view showing an example of a bellows type expansion joint according to the present invention, and the bellows type expansion pipe joint has an arithmetic unit and a remaining life display device. The upper half of the center line of the bellows type expansion joint is shown in cross section.
A plurality of limit switches 4 are attached to the bellows type expansion joint 1 shown in the example of the figure as detection means for detecting expansion and contraction, and each limit switch 4 is connected to the arithmetic unit 3. . The arithmetic device 3 and the remaining life display device 8 are integrated. Reference numeral 10 denotes a stopper for fixing between the flanges so that the bellows-type expansion pipe joint does not expand and contract before installation, and after the bellows-type expansion pipe joint is installed, it can be easily pulled out in the radial direction.
[0013]
The bellows-type expansion tube joint 1 includes a bellows 2 and a pair of joint portions 9, and a pair of joint portions 9 are connected to both sides of the bellows 2. Further, flanges 6a and 6b are attached to the end portion of the joint portion 9 connected to the bellows 2, and a plurality of shafts 5 for assisting expansion and contraction of the bellows 2 are attached between the flanges in the longitudinal direction. ing. The shaft 5 passes through the flange 6b and is fixed at the flange 6a. Each shaft 5 is provided with a plurality of sets of stoppers 7 a and 7 b according to the amount of expansion and contraction of the bellows 2. Limit switches 4 are attached to the surfaces of the stoppers 7a and 7b facing each other. The limit switch 4 opens and closes in contact with the flange 6b by the expansion and contraction of the bellows 2, and detects the expansion and contraction of the bellows.
[0014]
FIG. 2 is a flowchart showing a process from the installation of the bellows-type expansion joint shown in FIG. 1 to displaying the remaining life. Further, in the arithmetic unit, the user has previously set a life repetition number Nc obtained by an equation according to “JIS B 2352-1994“ Strength Evaluation Criteria for Bellows-type Expansion Pipe Joint ””.
[0015]
In the example of FIG. 2, the arithmetic device 3 measures the number of repetitions by accumulating the number of expansions and contractions detected by the limit switch from the start of use until that time. Next, the arithmetic unit 3 calculates the remaining number of repetitions from the number of repetitions and the above life repetition number. Furthermore, the arithmetic unit 3 calculates the remaining life time and the remaining life days from the remaining number of repetitions and the number of repetitions per unit time. Note that the number of repetitions per unit time may be a value predicted and set by the user in advance, or may be a value calculated by the arithmetic device 3 from the elapsed time from the start of use and the number of repetitions. The remaining life display device 8 displays these.
In the above, the user can set the number of repetitions of the life, and thereafter, the replacement time can be grasped only by attaching the bellows-type expansion joint, so that the burden is reduced as compared with the conventional case.
[0016]
The bellows type expansion joint 1 is provided with means for detecting expansion and contraction of the bellows 2. The extent of expansion / contraction to be detected may be determined according to the design conditions, usage status, usage purpose, etc. of the bellows type expansion joint 1 and is not particularly limited. The detection means for detecting the expansion / contraction of the bellows is not particularly limited, and examples include a detection means by opening / closing a limit switch as shown in FIG. However, since it is often exposed to the outdoors and operated, care should be taken so that it will not become inoperable due to sticking due to rust for many years.
[0017]
The arithmetic device 3 is not particularly limited as long as it can calculate the remaining life. The remaining life here may be information that allows the user to grasp the replacement timing of the bellows, and is not limited to the remaining number of repetitions, remaining life time, remaining life days, for example, the number of life repetitions. A combination with the number of repetitions from the start of use to the present time, a combination of a lifetime (days) and a time from the start of use to the present time (days), or the like may be used.
[0018]
The calculation device 3 is a function necessary for calculating the remaining life, for example, an integration function for integrating the detected expansion and contraction, a clock function for measuring the elapsed time from the start of use to the present time, any set value, calculated value, measurement What has the memory | storage function etc. which memorize | stores a value etc. is preferable. The configuration of the arithmetic device 3 is not limited, and may be configured using an existing electric circuit or the like. The arithmetic unit may be provided integrally with the bellows type expansion joint, or may be provided separately.
[0019]
The remaining life display device 8 is not particularly limited as long as it allows the user to grasp the remaining life calculated by the calculation device. The remaining life display device 8 itself may have a display means, or may be a device that outputs to an external display means. It is preferable that the remaining life display device 8 can display not only the remaining life but also other information required by the user as required by the user. Furthermore, the remaining life display device may be integrally attached to the bellows-type expansion / contraction pipe joint 1 or the arithmetic device 3, or may be a separate body.
[0020]
Examples of the display means of the remaining life display device include a liquid crystal display and a light emitting diode.
Further, if the remaining life display device is a device that outputs to an external display means, examples of the device include a device that sends data to the outside through an output terminal, a device that writes data to a recording medium such as a floppy disk, and the like.
[0021]
Of the configuration of the bellows-type expansion / contraction pipe joint of the present invention, a known general bellows-type expansion / contraction pipe joint may be used for the parts other than the detection means, the arithmetic unit, the remaining life display device, etc., and is particularly limited. It is not something. The present invention is particularly useful for a bellows type expansion joint that breaks due to repeated displacement and stress.
[0022]
【Example】
Hereinafter, the present invention will be specifically described with reference to examples.
Actually, the bellows type expansion joint shown in FIGS. 1 and 2 was manufactured and installed in the piping facility. As the bellows-type expansion joint, a bellows-type expansion joint specified in JIS B 2352 (diameter: 200 A, axial displacement: 110 mm, inter-surface length L ₀ : 1400 mm) was used. The number of repetitions of life is 3000 times. Further, four sets of limit switches were attached to the stoppers in the same manner as in FIG.
[0023]
An arithmetic unit having a function of storing the number of repetitions of the lifetime and a function of integrating the number of expansions and contractions detected by the limit switch was used. As the remaining life display device, a device having a liquid crystal display capable of displaying the number of repetitions of life and the number of expansion and contraction was used. The arithmetic unit uses a commercially available counter and a computer used for the sequence control circuit, and is configured to be able to display a display from the counter output signal by computer arithmetic.
[0024]
When the above bellows expansion / contraction pipe fitting is installed in piping equipment, the user can always check the set number of repetitions of life and the number of repetitions from the start of use to the present time, and can easily grasp the remaining number of repetitions. Compared to the conventional system, the management burden on the user is reduced.
[0025]
【The invention's effect】
In the bellows type expansion pipe joint of the present invention, the bellows type expansion pipe joint can be managed without setting the replacement time of the bellows type expansion pipe joint in advance, and the replacement time becomes unclear as in the past. Can be eliminated. Furthermore, since the user can also visually confirm the necessary information, the user can easily grasp the replacement time of the bellows type expansion joint, and the burden on the user is reduced.
[Brief description of the drawings]
FIG. 1 is a side view showing an example of a bellows type expansion joint according to the present invention.
FIG. 2 is a flowchart showing a process from installation of the bellows type expansion joint according to the present invention to display of the remaining life.
FIG. 3 is a side view showing an example of a conventional bellows type expansion joint.
[Explanation of symbols]
1 Bellows type expansion joint 2 Bellows 3 Computing device 4 Detection means (limit switch)
8 Remaining life display device

Claims (2)

A bellows type expansion joint having a detection means capable of detecting expansion and contraction of a bellows. The bellows-type expansion joint according to claim 1, further comprising: an arithmetic unit capable of calculating the remaining life of the bellows-type expansion joint from information relating to expansion and contraction detected by the detection means; and a remaining-life display device for displaying the remaining life.

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