JPS58216924A - Rail stress detecting system - Google Patents

Abstract

PURPOSE:To measure the axial tension of a rail by a magnetic anisotropic detection sensor, by averaging four peak output values accompanied by magnetic anisotropy yielded by stress, based on the output of the magnetic anisotropic sensor, and performing correction based on the temperature. CONSTITUTION:A rail axial tension detecting sensor 17 is attached to a rail. When an anisotropic sensor 8 is rotated, signals are obtained for 0 deg.-360 deg.. Four peak values are detected by a peak value detecting circuit 26. Said peak value data are sequentially added, and an average value is computed by an average value circuit 30. The corresponding rail axial tension is read from said average value by a converter 31 and displayed on a display device 32. The value of the rail axial tension is corrected by the temperature data from a thermometer 18 in a temperature correcting circuit 33 so as to obtain the value of the standard temperature. The value is compared with upper and lower limit values in a comparator 34. When the value exceeds the limit value, a signal is outputted and displayed on the display circuit 32.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a track stress measuring method for checking the stable state of track stress by measuring the internal stress of a rail caused by changes in temperature.

There are various types of force in the track structure of railway tracks. Representative ones are shown in Figure 1 (al, (1)). In the figure, the roadbed 2, mainly made of gravel, is raised 1° on top of the roadbed 1.
Arrange sleepers 3 on top of this trackbed 2, and then.

Place the left and right rails 4at4b on top of sleeper 3.

It is fixed at 5. Rail 4 is usually 25M.

A long one is used, and the end of each rail 4 is a seam.

They are fastened with bolts using plates 6 and are in contact with each other 1-.

It is continued. Tj Oh, what is called a long rail,
Unit rails of 200M length are connected by welding on site and used as one piece of 1KM or more.

Here, looking at the mechanical state of the track against the judge load, we can see that not only are the sleepers 3 and the rails 4 connected to a ladder structure, but also the roadbed 1 and the trackbed 2 are connected to each other, and the trackbed 2 and the sleepers 3 are connected to each other.
the frictional resistance that exists between

or inertial resistance (these are collectively referred to as track bed resistance).

(b) is a structure that is synthesized as a single unit and maintains mechanical balance in spite of the strong and highly variable dynamic loads applied by a running train. .

The effect of external temperature on the mechanical equilibrium of the orbit described above.

The effects of degrees and their fluctuations are profound. First of all, the temperature change in the orbit itself is much larger than the outside temperature. In the summer, it directly absorbs solar radiant heat, and it is not uncommon for temperatures to reach 60°C, depending on ambient conditions. In addition, during the harsh winter months, the orbital temperature drops to the same temperature as the atmosphere or lower.

do. In short, if the range of change in outside temperature is 50°C, the rails and rails can be assumed to have a range of fluctuation of well over 80°C.

There is no problem. Due to such orbital temperature changes.

Naturally, an expansion and contraction force occurs in the rail 4, but...

Le 4 cannot freely expand and contract at both ends, and the expansion and contraction force is high.

is latent inside as compressive or tensile force. 2. This is the internal stress, and the component of the internal stress in the longitudinal direction of the rail 4 is called the rail axial force. Note that internal stress also includes residual stress, which is a part of the external force that remains during the rail manufacturing process.

If the rail axial force mentioned above exceeds the safety limit and becomes an abnormally large value, the situation is dangerous. That is,
If an abnormally large tension or force is generated due to low temperature, the fastening bolts of the joint plate B may break or break, or the rail itself may break. Also, if an abnormally large compressive force occurs during high temperatures in the summer, and the orthogonal component of the orbit overcomes the orbital resistance.

Ladder structures made of rails and sleepers are prone to skidding.

wake up This is the so-called buckling phenomenon, and it is extremely important.

This can lead to serious offshore accidents. .

In order to maintain the mechanical equilibrium state of the track at an optimum temperature of 1°, track maintenance is performed with a temperature of 25°C as the standard during track construction or rail replacement.

That is, at this temperature, the rail 4 is placed in a predetermined position, the gap 7 of the rail joint is set to a specified value, and the joint plate 6 is fastened to fix the rail 4. In this case, the temperature is low.

If the rail temperature is less than 25°C, the above settings are made after heating the rail to 25°C.

However, even on a track that has been optimally adjusted, changes in the roadbed or roadbed can cause changes in the mechanical state of the track.・When this is combined with the temperature changes mentioned above, the rail・An abnormal state of axial force occurs.

In order to maintain the stability of the track, which is the basis of safe operation on the offshore coastline, we measure the rail axial force and study the mechanics of the track.

This is why it is desirable to understand the equilibrium state.

Ru. However, the track remains in operational use.

Regarding the method of measuring the axial force of the rail.

Measurement sensors have not yet been put into practical use. 1゜This invention is based on magnetic anisotropy, which has been recently developed.

A track stress test that measures the rail axial force by applying a stress detection sensor to the track, refers to the rail temperature at that time, and displays an indication when the rail axial force exceeds the control limit. We propose a method.

The purpose is to provide

The first point of this invention is a magnetic anisotropy detection sensor.

The purpose of this method is to measure the rail axial force using an anisotropic sensor (hereinafter simply referred to as an anisotropic sensor). So, there's something different.

Let's briefly talk about the directional sensor. In general, magnetic phenomena of magnetic materials when stress exists inside 5.

There is a difference in the degree of magnetization depending on the direction, and this is called magnetic anisotropy. Another way of looking at it is that magnetic resistance differs depending on the direction of stress/force. - The direction in which the degree of magnetization is high is the 1+ direction in which magnetic resistance is low, and this direction is called the axis of easy magnetization. .

As shown in FIG. 2(a), there are two cores 9 having windings E, E2 and D, respectively, on both legs.
a.

9b are arranged in a mutually orthogonal relationship, FIG.

As shown in (b), coils E, E, and coils,
D and D are connected in series, and the former is an excitation coil and the latter is a detection coil.

Illu. Such an anisotropic sensor 8 is illustrated.

When placed on the magnetic material 10 as shown in FIG.
A kind of transformer is formed by the magnetic material 10. That is, when a current ie of an appropriate frequency is passed through the excitation coils E, E2, the current is applied to the detection coil D, I)2.

A pressure Vd is induced. In this case, when magnetic anisotropy/tropism exists in the magnetic body 10, the angle formed by the direction of the axis of easy magnetization and the direction of the excitation/vibration coils E, B (iF is the core ・9a
, 5 magnetic resistance of the magnetic circuit composed of 9b and the magnetic body 10 changes between balanced and unbalanced.

do. Here, the detection coils D and B2 are wave-wound, but when they are balanced, the magnetic flux is canceled out.

Vd = 0, and the degree of imbalance is significant.

Ru. Therefore, voltage Vd increases. Note that the characteristics of Vd are opposite when the stress is 1° in tension and compression.

Figure 3 shows the variation of voltage Vd with respect to angle θ.

The angle θ is the axis of easy magnetization A and the excitation angle.

The angle formed with the plane containing Ile E, B2, θ; 45°,
.

A four-lobed black 15-bar shape is drawn with maximum values at 135°, 225° and 315°.

Now, as I mentioned earlier, magnetic anisotropy is a phenomenon caused by internal stress, so when a certain internal stress state shows magnetic anisotropy as shown by the solid line in Figure 3, if an external force is further applied. or if the internal stress changes due to temperature changes.

The pattern in Figure 6 is the original batan (fruit) as shown by the dotted line.

The size changes similarly to the line). - The rail is a ferromagnetic material, and it has been known since the beginning of its manufacture that internal stress exists, as illustrated in Figure 4. In the figure, the curves indicate isobar lines; - The direction of the force is the rail axis direction, that is, axial force; - The positive sign of the numerical value means tensile force, and the negative sign of the numerical value means compressive force.

Therefore, the inventors conducted an experiment regarding the magnetic anisotropy of the rail at 11 degrees. That is, as shown in FIG. 5(a).

, in the axial direction of the rail 4 by the load testing machine 11.

Apply compressive force P. The anisotropic sensor 8 is shown in FIG. 5(b).

If it is placed on the top of the bottom of the rail 4 as shown in Figure 5 (C
1 data has been changed. First, call P-o.

The voltage Vd has an initial value, and as P increases, the voltage Vd clearly increases. Here, when P is decreased, the voltage Vd is decreased, but in this case, a hysteresis phenomenon is exhibited.

Next, similar tests were performed at various points on the rail surface, and the changes in voltage at each point between the initial value (P-○) and P-40) were measured.

The quantity ΔVd was calculated. This and the rail 4 shown in Figure 4.
The relationship between residual stress σ on the cross section of is shown in Figure 5(d).
Shown below. In other words, the horizontal axis is σ, and the vertical axis is the amount of change in voltage/voltage △
When Vd is taken, the relationship between these is clear and is 5. In other words, when the stress σ is large, the magnetic anisotropy (probably the residual magnetism itself) is saturated, so even if P is changed, the voltage V
d does not change. .

Based on the above facts, the 1° relationship between the external force P and the voltage Vd at a specific point on the rail surface is determined in advance for each rail type. Also, crotch under standard conditions (25°C).

rail temperature and sensed voltage for a given track.

When measuring Vd, draw the standard curve S in Figure 6.

Can be done. For such a standard curve S, Ren.

The voltage Vd obtained by measuring the anisotropy of the desired track is converted into a -rail axial force, which is then converted into temperature to determine whether 17 is correct or not. U in Figure 6 is the control limit line (upper limit);
L is the same (lower limit).

In this invention, the voltage due to magnetic anisotropy is measured, the rail axial force is estimated from this, and the rail axial force is determined to be inappropriate by referring to the temperature.

This constitutes an inspection system that can do this.

This is the second point of this invention.

Fig. 7 (al, (b), fc) shows trajectory inspection according to the present invention.

This figure shows the appearance of the structure on the downstream side of the rail axial force detection sensor 17 used in the system. The anisotropic sensor 8 is.

There are four discs made of magnetic material on disk 12 made of magnetic material.

Each round rod has a core with round rods 16 screwed symmetrically.

Wind the coil 14 around. The connection is shown in FIG. 2 already mentioned.

According to (b). Next, the anisotropic sensor 8 is made of a non-magnetic material.
.

It is placed in a case 15 and the lid 16 is 85°.The lid 16 is anisotropic.

It is fixed to the sensor 8 and to the case 15.

The structure allows for 360° rotation. In other words, K.

The lid 16 can be rotated as shown by the arrow C, and the electrical contacts Sa,
Assume that So is closed.

FIGS. 8(a) and 8(b) show the above-mentioned axial force detection sensor 17.
This is an embodiment of the fixture 19 for attaching the rail to the upper part of the bottom of the rail.The fixture 19 is made of a non-magnetic material and has the shape shown in the figure, and can be inserted into the bottom of the rail by external force and fixed to the rail 4 by tightening with a butterfly. be. A circular hole is provided in the fixture 19, into which the case 8 of the axial force detection sensor 17 is pushed and fixed.

Here, anisotropy.

The tip of the round bar 13 of the sensor 8 is connected to the surface of the rail 40.

It is possible to rotate 5 smoothly while being separated at a constant interval. Also, the temperature side of rail 4.

A thermometer 18 is embedded in the fixture 19 for temperature control. .

As a thermometer, the measured value is output as an electrical signal.

Use a surface thermometer.

FIG. 9(a) shows an embodiment of the block configuration of the orbital stress measurement system 10 according to the present invention, and FIG. 9(b) shows the main structure.

It is a time chart of important signal waveforms.　　　.

The anisotropic sensor 8 receives a more suitable frequency than the oscillator 22.

A number of excitation currents are given. - The force detection voltage Vd is level-adjusted by the amplifier 11@device 16, and synchronized by the synchronous detector 23 using a current with a frequency equal to the excitation current.

Detected. This reduces the noise of the detection voltage/Vd.

It is removed and then digitalized by the NΦ converter 24.

converted into a signal. Now, here and now, anisotropic se.

When the sensor 8 is rotated, the rotation angle of θ-0° to 660° is
No. 0 (a) can be changed. The signal (A) becomes the signal (B) by the absolute value circuit 25, and the signal (B) is sent to the peak detection circuit 26.
b) and.

Signal (b) is input. Here, the four beam values of the signal (a) are held and input to the gate 28 as the signal e→. At the same time, the peak detection circuit generates a timing signal indicating that the peak value is being held.

is created and given to the counter 27. Kalanri 2
In 7, the gate signal (E) is created by the signal ().

is applied to gate 28. The gate signal (E) is a pulse.

The number is 4, and 10 corresponds to the 4 peak values,
As a result, the peak value data that has passed through the gate 28 is successively added by the adder 29, and the average value is calculated by the next average value circuit 30. The reason for taking the average of the four peak values in this way is because magnetic anisotropy is not always symmetrical and the four peak values are not equal (), and to eliminate the influence of noise. For a reason.

be. The conversion circuit 31 handles this based on the average value Vd.

The rail axial force is read out and displayed on display 2.

It will be done. On the other hand, the temperature is determined by the temperature information from the thermometer 18.

In the degree correction circuit 33, the value of the rail axial force is:

It is corrected to the value of the standard temperature of 25°C, and the comparator circuit 34
.

It is compared with the lower limit value, and if the limit is exceeded, a signal is output and displayed on the display circuit 32. 6. As described above, the track stress measurement system of the present invention.

If the stem is applied to a track in production, it becomes a rail.

The axial force is directly read and the track is stabilized by referring to the rail temperature.

Judging the validity of mechanical equilibrium, which is an important key to stability.

It is possible to do this, and the effects are remarkable.

There is.

4. Brief explanation of the drawings 1゜Figures 1 (a) and (b) are explanatory diagrams of the track structure, Figure 2 (al.
,.

(b) is a diagram showing the magnetic anisotropy sensor structure and connections.

Figure 3 shows the detected voltage obtained by the magnetic anisotropy sensor.

Pressure baton (θ characteristics) diagram, Figure 4 Residual response of rail.

Force distribution diagram, Figure 5 (a), (b), (C) and (
d) is a rail.

An experimental method in which compressive force was applied to A structural diagram of an embodiment of the rail axial force detection sensor used in the inspection system, FIGS. 8(a) and 8(b) are an implementation of the mounting tool for attaching the rail axial force detection sensor shown in FIG. 7 to the rail. A diagram showing an example, ``Figure 9 (aL) (bl is the track stress test system according to the present invention.

FIG. 2 is a comprehensive block system diagram of the stem.

1...Road bed 2...Road bed 3...Sleepers
4...Rail 5...Large needle 6
...joint plate.

7... Air gap 8... Magnetic anisotropy sensor.

9...Core 1o River material 11...Load tester 12...Disc plate 1 (13...
・Round J 14... Coil 15... Case 16... Lid 17... Rail axial force detection sensor 18... Thermometer 19 River fitting 20... Butterfly nut 21... Amplifier 1522・
...Oscillator 26...Synchronized detector 24...
1 converter 25... Absolute value circuit 26... Peak detection circuit 27... Counter 28... Gate 29...
... Adder 30 ... Average value circuit 31 ... Conversion circuit
2゜32...Display 33...Temperature correction circuit 34...Comparison circuit 0 215゜O 1 O 7th (GoLn 4 (,To 7・) Sq3 and Toshi 7 No〆ichikut2) /!? 9-o (ku) 7 (・cho-)-111] L□-W2m1□□□□ □□□−
1] □−□□−−−−−□−−−30-0 Nakai-cho, Ashigarakami-gun, Kanagawa Inside Hitachi Electronics Engineering Co., Ltd.Applicant Hitachi Ltd. 5-1 Marunouchi-chome, Chiyoda-ku, Tokyo■ Applicant: Hitachi Electronics Engineering Co., Ltd.

Claims (2)

[Claims] (1) Based on the output of 5 magnetic anisotropy sensors that are attached to the surface of the rail that makes up the track and can be rotated in the range of 0° to 360°, 4 peaks associated with magnetic anisotropy (angle 45
The trajectory and stress are measured using the average value of the output (peak value for 135°, 225°, and 315°), and the measured value is corrected based on the temperature at the time of measurement.
Orbital stress taken as iVi3. Inspection method. (2) Made of magnetic material on a disk made of magnetic material. Center-symmetric the four round bars and make them the vertices of a square. A magnetic anisotropic sensor with a 1° coil wound around each of the four round bars is placed in a non-magnetic case. and the magnetic anisotropy with respect to the case. The sensor is rotatable in the range of 0° to 660°. Furthermore, the rotational position of the magnetic anisotropy sensor is 0°. and a magnetic insulator 91 having electrical contacts that close at 360°;
A patent application characterized by using a directional sensor. Required range Item 1: Soft track stress detection method. .