JPH08285778A - Loosening detector at joint of rail - Google Patents

Abstract

PURPOSE: To obtain highly reliable inspection results automatically. CONSTITUTION: A plurality of range finding sensors 5 for measuring the distance from a reference point to different points on a rail presser 4 for jointing rails R through fastening bolts 3, and a controller 6 for operating the fastening state of the fastening bolt 3 based on signals from the range finding sensors 5 are mounted on a vehicle traveling on the rail. The controller 6 comprises means 61 for converting an analog range finding signal received from the range finding sensors 5 into a digital range finding signal, means 62 for deciding the fastening state of the fastening bolt 3 by operating the difference between the range finding values from a plurality of range finding sensors 5 based on the converted digital range finding signal, and means 63 for outputting the decision results of the means 62. The means 62 decides that the fastening bolt 3 is loosened when the difference between the range finding values exceeds a previously inputted allowable value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a slack detecting device for a rail fastening device in which a rail laid for running a vehicle is fixed to a concrete substrate.

[0002]

2. Description of the Related Art Conventionally, a rail fastening device as shown in FIG. 6 has been known. The rail fastening device 1 includes an anchor nut 2 embedded in a concrete substrate B with its surface exposed, a fastening bolt 3 screwed to the anchor nut 2, and a state in which the fastening bolt 3 is penetrated. It is basically composed of a hairpin-shaped rail pressing piece 4 formed of a leaf spring fitted between the bolt head 31 and the anchor nut 2.

The tip end side of the rail pressing piece 4 is in a state in which leaf springs are laminated, and the lower protrusion R1 of the rail R is pressed from the left and right at this laminated portion to fix the rail R on the concrete substrate B. There is. The base end side (hairpin side) of the rail pressing piece 4 is supported by a receiving member 4a that conforms to the curved shape of the hairpin. A track pad P, which is a cushioning material, is provided between the rail R and the concrete substrate B so that the vibration of the vehicle traveling on the rail R is not directly transmitted to the concrete substrate B.

In such a rail fastening device 1,
The rail R is fixed on the concrete substrate B through the tip of the rail pressing piece 4 by the strong screwing of the fastening bolt 3 with the anchor nut 2.
The fastening bolt 3 must always be in a state where the rail pressing piece 4 is properly tightened.

However, when the vehicle repeatedly travels on the rail R, vibration may be generated in the rail R, and this vibration may loosen the strong fastening of the fastening bolt 3, and then the rail R is surely and firmly. Since it is no longer fixed to the concrete substrate B, such a condition must be immediately resolved for safety.

Therefore, conventionally, an operator goes around the rail on which the rail R is laid, and visually checks the fastening state of the fastening bolts 3, and sometimes the hammers are used to sequentially strike the fastening bolts 3 to strike them. It was also performed to diagnose the fastening state of the fastening bolt 3 from the sound.

[0007]

However, since the rail fastening devices 1 are innumerable along the rail R, all the rail fastening devices 1 have been visually observed or hit with the hammer H. However, in addition to requiring an extremely large amount of time and labor, it is difficult to properly and surely check all in such an inspection that relies on the sense of a person, and oversight often occurs.

[0008] From such a fact, the actual exploitation Sho 62-125
In Japanese Patent Laid-Open No. 104, a rail fixing hook tightening / loosening inspection device in which a part of the inspection method is mechanized is proposed. This inspection device is one in which a fastening member of a rail is continuously and automatically hit by a link mechanism attached to a plate that is detachable from a truck that travels on the rail.
It is explained that when this inspection device is applied, the inspector can easily check the fastening state by only listening to the striking sound, and the inspection time is shortened and the work safety is improved. .

However, in the one disclosed in Japanese Utility Model Laid-Open No. 62-125104, although the striking operation on the fastening member is mechanized, it is human hearing to judge the striking sound. For that reason, at least one inspector has to stick to the inspection for the inspection, and it cannot necessarily be said that sufficient rationalization has been achieved.

Further, since the striking sound is different for each fastening member due to the characteristics of each fastening member, the striking site, etc., it is very difficult to judge whether or not the fastening member is loose only by hearing, and it is highly skilled. Besides being required, there was a problem that the judgment result was not so accurate in nature.

The present invention has been made in order to solve the above-mentioned problems, and the inspection is automatically performed by simply moving the inspection vehicle with almost no human intervention, and the reliability is extremely high. It is an object of the present invention to provide a looseness detecting device for a rail fastening device that can automatically obtain a high inspection result.

[0012]

According to a first aspect of the present invention, there is provided a slack detecting device for a rail fastening device, wherein a vehicle traveling on a rail has a plurality of distance measuring sensors and a distance measuring signal from the distance measuring sensors. A control device for calculating the fastening state of the fastening bolt is mounted on the basis of the above, and the distance measuring sensor measures to the base end surface and the tip end surface on the rail pressing piece that fastens the rail via the fastening bolt. The control device is configured to measure a distance from a reference point, and the control device is configured to determine looseness of a fastening bolt based on measurement results of the plurality of distance measuring sensors. .

According to a second aspect of the present invention, there is provided a slack detecting device for a rail fastening device according to the slack detecting device for a rail fastening device according to the first aspect, wherein the control device includes an analog measurement signal input from the distance measuring sensor. A signal converting means for converting the distance signal into a digital distance measuring signal, and the fastening state of the fastening bolt by calculating the difference between the distance measuring values measured by the plurality of distance measuring sensors based on the converted digital distance measuring signal. And a means for outputting a determination result of the fastening state determining means, wherein the fastening state determining means allows the value of the difference between the distance measurement values to be inputted in advance. When the value is equal to or more than the value, it is set so as to determine that the fastening bolt is loose.

A slack detecting device for a rail fastening device according to a third aspect of the present invention is the slack detecting device for a rail fastening device according to the first or second aspect, wherein the distance measuring sensor measures a distance by a laser displacement meter. It is characterized by being configured.

According to a fourth aspect of the present invention, there is provided a slack detecting device for a rail fastening device according to the slack detecting device for a rail fastening device according to the third aspect, wherein the laser beam emitting surface and the reflected light receiving surface of the laser displacement meter are rails. It is characterized in that it is set to be parallel to the scanning direction with respect to the surface of the pressing piece.

[0016]

According to the slack detecting device for the rail fastening device of the first aspect, one of the rail pressing pieces scanned by each distance measuring sensor is operated by running the vehicle with the slack detecting device operating. Whether or not the rail is fastened by the fastening bolts by measuring the distances from multiple measurement points per rail pressing piece and calculating the inclination of the rail pressing piece based on this measurement result. To determine.

As described above, by adopting the device of the present invention, the slack detecting device is operated and the vehicle is driven, and the rail is automatically operated without relying on the visual inspection and hearing of the inspector as in the conventional case. It becomes possible to inspect the looseness of the fastening device.

According to the slack detecting device for the rail fastening device of the second aspect, the plurality of distance measuring sensors measure the distances from the plurality of measurement reference points for each one rail pressing piece, and the plurality of distance measuring sensors. The value is input to the control device as an analog distance measurement signal. Then, the signal conversion means in the control device converts the analog distance measurement signal into a digital distance measurement signal, and the fastening state determination means in the control device calculates the difference between the respective distance measurement values. When the result of this calculation is greater than or equal to the preliminarily input allowable value, the fastening state determination means determines that the fastening bolt is loose and transmits the signal to the output means. The output means that has received the signal outputs the fastening device in which the looseness has occurred by an appropriate method, and therefore, which fastening device is loose is specified by this output result.

According to the slack detecting device for the rail fastening device of the third aspect, since the laser displacement meter is applied as the distance measuring sensor, the distance between the reference point and the rail pressing piece is measured reliably and accurately. It can be performed.

According to the looseness detecting device of the rail fastening device of the fourth aspect, the laser light emitting surface and the reflected light receiving surface of the laser displacement meter are arranged in parallel with the surface of the rail pressing piece in the scanning direction. Since the setting is set, even if the rail pressing piece tilts in the width direction of the rail due to loosening, the specularly reflected light does not reach the light receiving surface, and as a result, the measured value is stable and the looseness of the rail fastening device is detected reliably. It will be possible.

[0021]

1 is a sectional view of a rail laying portion illustrating an installed state of a detection device according to the present invention, and FIG. 2 is a plan view illustrating a rail pressing piece. Further, FIG. 3 is an explanatory view of a side view illustrating an installation state of the detection device according to the present invention. As shown in these figures, a rail R for running a vehicle is placed on a concrete substrate B via a track pad P which is a cushioning material, and is outwardly directed to both lower side portions thereof. The protruding lower projecting portion R1 is fixed on the concrete substrate B while being pressed by the pair of rail fastening devices 1 provided on both left and right sides.
A pair of such rails R is laid in parallel to form a rail (not shown).

Inside the concrete board B on both sides of the lower part of the rail R, the anchor nut 2 is exposed with its surface exposed.
Is buried. A bolt hole 21 for screwing the rail fastening device 1 downward is screwed on the exposed surface of the anchor nut 2.

The rail fastening device 1 includes a rail pressing piece 4 made of a hairpin-shaped leaf spring, and the rail pressing piece 4
And a fastening bolt 3 for fixing the. A pair of upper and lower insertion holes 41 are bored in the substantially central portion of the rail pressing piece 4 so as to correspond to each other, and the fastening bolt 3 is inserted into these insertion holes 41, and the anchor nut 2 located below the insertion bolt 41. Is screwed into the bolt hole 21 of the.

The tip of the rail pressing piece 4 is
With the upper and lower leaf springs in contact with each other, the rail contact portion 42
Is formed, the rail abutting portion 42 presses the lower protruding portion R1 of the rail R downward, and the hairpin portion 4 is formed.
3 is supported by an elastic receiving member 4a arranged on the upper surface of the concrete substrate B. With the rail pressing piece 4 in such a state, the rail R becomes the concrete substrate B.
It is fixed on.

Therefore, by tightening the fastening bolt 3, the rail contact portion 42 of the rail pressing piece 4 is in a state of pressing the lower protruding portion R1 of the rail R from above,
Due to this pressing force, the rail R is fixed to the concrete substrate B in a stable state.

When the rail pressing piece 4 properly presses and fixes the rail R by tightening the fastening bolt 3, the upper surface of the rail pressing piece 4 is preliminarily set to be substantially horizontal. However, the fastening bolt 3
When the fastening state due to is loosened, the rail pressing piece 4 is formed of a leaf spring and is urged in the direction in which the hairpin is opened. Therefore, as shown in FIG. The rails R are separated from each other, and the pressing force on the lower protrusion R1 of the rail R is reduced.

The slack detecting device of the present invention was completed in view of this fact, detects the distance from the reference point to both surfaces sandwiching the fastening bolt 3, and the difference between these distances is detected in advance. It is configured to determine that the looseness of the rail fastening device 1 has occurred when it is larger than the set value.

In order to measure the distance from the reference point, in the present invention, as shown in FIGS. 1 and 3, a support frame C1 is laid under the floor of the vehicle C, and the inside of this support frame C1. Distance measuring sensor 5 is attached to. In the present invention, the distance measuring sensor 5 provided for the distance measurement has a known laser displacement meter S and a mechanism for converting the detection value detected by the laser displacement meter S into a predetermined current intensity. And a main body 51 that has been formed.

The laser displacement meter S continuously emits a laser beam from a light wave emitting hole (emission surface) S3 and hits an object (in the case of the present invention, the upper surface of the rail pressing piece 4) to cause a diffused reflection. A distance measuring instrument that receives the reflected light by the light receiving portion (light receiving surface) S4, detects the phase shift between the emitted light and the reflected light, and measures the distance from this phase shift to the object. Is extremely high, and is very suitable for an application such as the present invention that detects a slight difference in distance. In the present invention, the reference point for distance measurement is set at the position of the light wave emitting hole S3. Therefore, the distance measured by the laser displacement meter S is the distance from the light wave emitting hole S3 to the upper surface of the rail pressing piece 4.

In the example shown in FIG. 1, the laser displacement meters S are paired on the left and right with one rail R sandwiching the rail R, that is, the left displacement meter S1 (the first left displacement meter S11).
And the second left displacement meter S12) and the right displacement meter S2.
A total of four (right first displacement gauge S21 and right second displacement gauge S22) are provided. Therefore, since the vehicle C inspects two rails, a total of eight laser displacement gauges S are provided per vehicle C.

The two left displacement gauges S1 emit laser light toward the upper surface of the left rail pressing piece 4 shown in FIG. 1, and the right displacement gauge S2 emits laser light onto the upper surface of the right rail pressing piece 4. It emits a laser beam toward it. Specifically, the first left displacement meter S11 faces the surface of the rail pressing piece 4 on the left side of the left fastening bolt 3, and the second left displacement meter S12 faces the surface of the rail pressing piece 4 on the right side. Emits a laser beam and the right first displacement meter S21
Is set so as to emit laser light toward the surface of the rail pressing piece 4 on the left side of the right fastening bolt 3, and the second right displacement meter S22 is set to emit laser light toward the surface of the rail pressing piece 4 on the right side thereof. ing.

Therefore, for the left rail pressing piece 4,
The distance from the reference point to the surface of the left and right rail pressing pieces 4 with the fastening bolt 3 as a boundary is measured by the first left displacement meter S11 and the second left displacement meter S12, and the right rail pressing piece 4 is also measured. Similarly, it is measured by the first right displacement meter S21 and the second right displacement meter S22.

The distance from the reference point to the surface of the rail pressing piece 4 is measured by the laser displacement meter S by running the vehicle C. Regarding the distance measurement, the range of the measured distance is set in advance within the variation range of the rail pressing piece 4, and the outside of this range is excluded as the object of distance measurement even if the result of the distance measurement is obtained. Is configured.

Therefore, the vehicle C travels in the direction shown by the one-dot chain line arrow in FIG. 2, and the laser beam scanning is performed by the first left displacement meter S11 and the second left displacement meter S12 as shown by the same one-dot chain line. In this state, the distance is measured only when the laser beam scans the surface of the rail pressing piece 4, but the rail pressing piece 4 does not exist before and after that, and clearly deviates from the range of the measured distance. Laser displacement meter S
Even if the distance measurement is performed by, the obtained value is excluded from the calculation target.

The installation posture of the laser displacement meter S is important. That is, in the present invention, as shown in FIG.
The light wave emitting hole (emission surface) S3 and the reflected light receiving portion (light receiving surface) S4 of the laser displacement meter S are set to be parallel to the rail pressing piece 4 in the scanning direction, that is, the moving direction of the vehicle C. ing. By setting in this way, even if the rail pressing piece 4 tilts in the width direction of the rail R due to loosening of the fastening, only the diffused reflected light necessary for distance measurement is supplied to the light receiving portion S4, and the specular reflected light is received. It does not reach the portion S4, and as a result, the measured value becomes stable, and it becomes possible to reliably detect the looseness of the rail fastening device 1.

The emitted light emitted from the laser displacement meter S,
The calculation of the distance between the reference point and the surface of the rail pressing piece 4 based on the phase difference from the reflected light reflected on the surface of the rail pressing piece 4 is executed in the main body 51 of the distance measuring sensor 5. ing. Then, in the main body 51,
The distance measurement value is converted into an analog distance measurement signal depending on the strength of the current and is input to the control device 6 shown in FIGS.

The control device 6 is based on the signal converting means 61 for converting an analog distance measuring signal input from the main body portion 51 of the distance measuring sensor 5 into a digital distance measuring signal, and the converted digital distance measuring signal. A fastening state discriminating means 62 for discriminating the fastening state of the fastening bolt 3 by calculating the difference between the distance measurement values measured by the plurality of laser displacement meters S, and an output for outputting the discrimination result of the fastening state discriminating means 62. Means 63 are provided.

In the present invention, the fastening state discriminating means 62 discriminates that the fastening bolt is loose when the value of the difference between the distance measurement values is equal to or more than the previously inputted permissible value. It is configured to do.

Explaining it concretely by the example shown in FIG. 1, the left first displacement meter S for the rail pressing piece 4 on the left side.
Reference numeral 11 measures the distance from the reference point to the upper surface on the left side of the rail pressing piece 4 (hereinafter referred to as the first distance), and the left second displacement meter S
12 measures the distance to the upper surface of the right side (hereinafter referred to as the second distance).

Then, the measurement result is converted into an analog distance measuring signal in the main body 51, and each analog signal is input to the signal converting means 61. This analog signal is
The signal converting means 61 converts the signal into a digital distance measuring signal and inputs it to the fastening state determining means 62. In the fastening state determination means 62 to which the digital distance measurement signal is input, the distance measurement value by the first left displacement meter S11 and the distance measurement value by the second left displacement meter S12 are compared and calculated (specifically, both The difference is calculated and whether or not the value of this difference exceeds a preset allowable value is compared.

FIG. 4 is an enlarged cross-sectional view exemplifying a fastening state of the rail by the rail pressing piece, showing a state where the rail is normally fixed. The alternate long and short dash line shows the reference level for distance measurement. In this case, the value x of the first distance measured by the first left displacement meter S11 and the value y of the second distance measured by the second left displacement meter S12 are substantially equal (that is, the difference between the two). The value is within a preset allowable value range). Therefore, the fastening state determination means 62 determines that the rail pressing piece 4 normally fastens the rail R and that there is no looseness.

On the other hand, FIG. 5 shows a state in which the rail R is loosely fastened by the rail pressing piece 4. In this case, the leaf spring on the upper right side of the rail pressing piece 4 is lifted up due to the loosening of the fastening bolt 3, and the lower protruding portion R1 of the rail R is properly pressed and sandwiched by the rail pressing piece 4. Not not. That is, the rail fastening device 1 is in a loose state.

Therefore, in this case, a difference d is formed between the distance measurement value (first distance) of the left first displacement meter S11 and the distance measurement value (second distance) of the left second displacement meter S12. Will be. When the difference d exceeds the preset allowable value, the fastening state determination means 62 determines that and determines that the rail fastening device 1 is loose.

The result of the determination made by the fastening state determining means 62 is transmitted to the output means 63 in the control device 6 and displayed on the display or printed out. In addition to these, if the result of the determination indicates that the rail fastening device 1 is loose, an alarm is issued.

A keyboard or the like is provided in the control device 6 in order to instruct the operation or stop of operation of the looseness detecting device of the rail fastening device and to input various set values. The input means 64 is provided. The operation of the detection device itself is controlled by a predetermined input operation from the input means 64.

Since the looseness detecting device for the rail fastening device of the present invention is constructed as described above, in order to check the looseness of the rail fastening device 1, the vehicle C equipped with the looseness detecting device is installed.
Need only be run on the track to be inspected, and a command for operating the device should be input from the input means 64. Then, the laser displacement gauge S of the running vehicle C emits laser light toward both sides of the rail R, and the distance from the reference point to both sides of the rail pressing piece 4 is measured. Then, the measurement result is analyzed in the control device 6, and when there is a difference in the above distance measurement values on both sides of the rail pressing piece 4 beyond the allowable range, it is determined that the rail fastening device 1 is loose, and That is displayed by the output means 63.

As described above, when the device of the present invention is used, the rail fastening device can be achieved with speed and certainty that cannot be achieved by the conventional visual observation that takes time and labor and the hitting sound caused by hitting with a hammer or the like. It becomes possible to detect the looseness of No. 1 and it is extremely useful for labor saving of the inspection work.

[0048]

As described above in detail, the looseness detecting device for the rail fastening device according to the present invention is suitable for vehicles running on rails.
A plurality of distance measuring sensors that measure the distance from the measurement reference point to different positions on the rail pressing piece that fastens the rail via the fastening bolts, and the above fastening based on the distance measuring signals from the distance measuring sensors. A control device for calculating the fastening state of the bolt is mounted, and the control device is configured to determine looseness of the fastening bolt based on the measurement results of the plurality of distance measuring sensors.

Therefore, by moving the vehicle while the device is in operation, the distances from a plurality of measurement reference points per rail pressing piece are measured for all the rail pressing pieces scanned by each distance measuring sensor. Then, the control device can easily determine whether or not the fastening of the rail by the fastening bolt is loose by calculating the inclination and the like of the rail pressing piece based on the measurement result.

That is, by adopting the device of the present invention, the slack detecting device is operated and the vehicle is run, and the rail fastening device is automatically operated without relying on the visual inspection and hearing of the inspector as in the conventional case. It becomes possible to quickly and surely perform the looseness inspection of the rail fastening device, which requires a lot of manpower and time, and it is extremely effective in rationalizing the inspection work.

Signal converting means for converting an analog distance measuring signal input from the distance measuring sensor into a digital distance measuring signal in the control device, and the plurality of distance measuring sensors measure based on the converted digital distance measuring signal. The fastening state discriminating means is provided with a fastening state discriminating means for discriminating the fastening state of the fastening bolt by calculating a difference between the respective distance measurement values, and an output means for outputting the discrimination result of the fastening state discriminating means. If the difference between the distance measurement values is equal to or more than the previously input allowable value, it is set so that it is determined that the fastening bolt is loose. Distances from a plurality of measurement reference points are measured per one side, and the plurality of distance measurement values are input to the control device as analog distance measurement signals.

Then, the signal converting means in the control device converts the analog distance measuring signal into a digital distance measuring signal, and the fastening state discriminating means in the control device calculates the difference between the respective distance measuring values. When the result of this calculation is greater than or equal to the preliminarily input allowable value, the fastening state determination means determines that the fastening bolt is loose and transmits the signal to the output means. The output means that has received the signal outputs the fastening device in which the looseness has occurred by an appropriate method, and which fastening device is loose is specified by this output result. Immediately, the tightening bolt tightening process of the specified rail pressing piece can be performed.

If the above distance measuring sensor is used to measure the distance by the laser displacement meter, the distance between the reference point and the rail pressing piece can be measured quickly, reliably and accurately, so that the vehicle travels at high speed. Even if it is done, it is possible to sufficiently deal with it, and the efficiency of the inspection work can be achieved.

If the laser light emitting surface and the reflected light receiving surface of the laser displacement meter are set to be parallel to the surface of the rail pressing piece in the scanning direction, the looseness of the fastening causes the rail pressing piece to move to the width of the rail. Even if tilted in the direction, the specularly reflected light does not reach the light receiving surface, and as a result, the measured value becomes stable and the looseness of the rail fastening device can be reliably detected.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a rail laid portion illustrating an installation state of a detection device according to the present invention.

FIG. 2 is a plan view illustrating a rail pressing piece.

FIG. 3 is a side view illustrating an installation state of the detection device according to the present invention.

FIG. 4 is an enlarged cross-sectional view illustrating a fastening state of the rail by the rail pressing piece, showing a state in which the rail is normally fixed.

FIG. 5 is an enlarged cross-sectional view illustrating a rail fastening state by a rail pressing piece, showing a state in which the rail fastening is loose.

FIG. 6 is a cross-sectional view of a rail for explaining inspection of a conventional rail fastening state.

[Explanation of symbols]

 1 rail fastening device 2 anchor nut 3 fastening bolt 31 bolt head 4 rail pressing piece 4a receiving member 5 distance measuring sensor S laser displacement meter S11 left first displacement meter S12 left second displacement meter S21 right first displacement meter S22 right second Two displacement gauges S3 Laser light emitting hole S4 Reflected light receiving portion 51 Main body portion 6 Control device 61 Signal converting means 62 Fastening state determining means 63 Output means 64 Input means B Concrete substrate C Vehicle C1 Support frame R Rail R1 Lower protruding portion

Front page continued (72) Inventor Takatoshi Tanaka 1-4-1, Mei Station, Nakamura-ku, Nagoya Tokai Passenger Railway Co., Ltd. Kobe Steel Works Takasago Works (72) Inventor Mitsuto Shinagawa 2-3-1, Niihama, Arai Town, Takasago City, Hyogo Prefecture Kobe Steel Works Takasago Works, Ltd. (72) Inventor Mitsuo Binko 2-3 Niihama, Arai Town, Takasago City, Hyogo Prefecture No. 1 Inside Takasago Works, Kobe Steel, Ltd.

Claims (4)

[Claims] 1. A vehicle traveling on a rail is equipped with a plurality of distance measuring sensors, and a control device for calculating a fastening state of the fastening bolts based on a distance measuring signal from the distance measuring sensors,
The distance measuring sensor is configured to measure the distance from the measurement reference point to the base end surface and the tip end surface on the rail pressing piece that fastens the rail via fastening bolts, and the control device is configured to control the plurality of distances. A looseness detecting device for a rail fastening device, which is configured to determine looseness of a fastening bolt based on a measurement result of the distance measuring sensor. 2. The control device includes a signal converting means for converting an analog distance measuring signal input from the distance measuring sensor into a digital distance measuring signal, and the plurality of distance measuring means based on the converted digital distance measuring signal. The fastening state determination means for calculating the difference between the distance measurement values measured by the distance sensor to determine the fastening state of the fastening bolt, and the output means for outputting the determination result of the fastening state determination means are provided. The state determination means is set so as to determine that the fastening bolt is loosened when the value of the difference between the distance measurement values is equal to or greater than the previously input allowable value. The looseness detecting device for the rail fastening device according to claim 1. 3. The looseness detecting device for the rail fastening device according to claim 1, wherein the distance measuring sensor is configured to measure a distance by a laser displacement meter. 4. A laser beam emitting surface and a reflected light receiving surface of the laser displacement meter are set to be parallel to the surface of the rail pressing piece in the scanning direction. Looseness detection device for rail fastening device.