RU228875U1 - RAILWAY WHEEL - Google Patents

Abstract

The utility model relates to railway wheels used for installation of automatic control and number accounting devices on railway transport. It can be used to obtain reliable information when identifying railway wheels. The technical result of the utility model consists in expanding the arsenal of technical means for making annular grooves on the hub of a railway wheel. In addition, the utility model provides optimal parameters for the location and geometry of the groove, which ensure stable wheel endurance and reduce the risk of cracks due to the groove. The specified technical result is achieved due to the fact that a railway wheel is claimed, having an annular groove in the hub area, where the groove has a transition surface from the walls to the bottom of the groove, characterized in that the annular groove is made with a depth of no more than 8 mm, a width of no more than 15 mm and with a distance from the end of the wheel hub of no less than 20 mm, and also has a transition surface from the walls to the bottom of the groove with a radius of curvature of no less than 2 mm.

Description

The utility model relates to railway wheels used for installation of automatic control and number accounting devices on railway transport. It can be used to obtain reliable information when identifying railway wheels.

When forming or repairing wheel pairs at railway transport enterprises, the wheel number is in most cases recorded manually in the accounting and reporting forms of the wagon economy. This existing practice leads to duplication and distortion of information. It should also be noted that the current marking system does not provide the ability to identify the wheel number in motion at different speeds due to the fact that the existing marking is applied to the outer side of the rim, subject to wear during operation, and, ultimately, becomes illegible. The lack of reliable electronic information about the wheels prevents the deployment of a pre-failure condition control system for wheelsets to ensure a higher level of safety in the transportation process. The transfer of wheel pair parameters in the operating mode is carried out without reference to a specific wheel pair, and is limited to the ordinal number of the wheel pair under a specific wagon.

There are a number of known solutions in technology that propose automatic identification of railway wheels while a train is moving.

A solution is known for patent for utility model No. 168729 "RAILWAY WHEEL WITH RADIO FREQUENCY IDENTIFICATION MEANS", published: 17.02.2017, which describes a railway wheel containing identification tags fixed thereto, characterized in that passive radio frequency tags (RFID) are placed on the side surface of the hub on the inner side in the transition zone from the cylindrical surface to the toroidal one. Passive radio frequency tags (RFID) are installed on the wheel hub at an equal distance from each other in the zone of the cylindrical part of the hub, enclosed between its end and the beginning of the toroidal surface. The tags are designed with the possibility of reading them in a static state of the wheelset by hand-held readers or automatic floor radio frequency identification means when the car is moving in the entire range of ambient temperatures.

The closest analogue of the proposed solution is patent for utility model No. 219987, published: 17.08.2023 for a railway wheel having a recess on the surface for placing an identification mark, characterized in that at the junction with the recess for placing the identification mark on the railway wheel, a transition surface is made, which is presented in the form of a rounding made along a radius of 1 to 3 mm.

The technical result that the utility model is aimed at achieving consists in reducing the risk of local cracks appearing in the area of the recess for placing the identification mark.

The disadvantage of this solution is that the size of the transition surface is indicated, but its size is indicated for certain sizes of the annular groove, while a fairly wide variability of such sizes is given.

Moreover, it is completely unclear how an identification mark can be fixed in such a groove.

The same drawback is found in the solution for the patent for invention No. 2788012, published: 16.01.2023 “RAILWAY WHEEL” and having the same essence.

The technical result of the utility model consists in ensuring optimal parameters of the location and geometry of the groove, which ensure stable wheel endurance and reduce the risk of cracks due to the groove.

The specified technical result is achieved due to the fact that a railway wheel is claimed, having an annular groove in the hub area, where the groove has a transition surface from the walls to the bottom of the groove, characterized in that the annular groove is made with a depth of no more than 8 mm, a width of no more than 15 mm and with a distance from the end of the wheel hub of no less than 20 mm, and also has a transition surface from the walls to the bottom of the groove with a radius of curvature of no less than 2 mm.

Preferably, at least three identification marks are fixed inside the groove using a fastening tape with a lock and compound.

Preferably, RFID radio frequency tags are used as identification tags, the operating frequency of which with a compound layer applied on top is in the range of 863-868 MHz.

Preferably, RFID tags with a frequency of within 980 MHz are used as identification tags.

Preferably, the upper edge of the hub surface is formed with a transition surface having chamfers with an angle of 45° or roundings.

Preferably, the identification marks are fixed in the groove made at the same angular distance from adjacent marks.

RFID tags are used as identification tags, with the ability to read information from them at speeds of up to 150 km/h.

Preferably, the identification tags are laid between two layers of compound, where the tags are located axially with the tape, so that the tag chip is closer to the edge of the smallest side of the wheel.

The fastening of a metal or plastic tape in a ring groove is accomplished by pouring an additional layer of compound on top.

Also, fastening of a metal or plastic tape in a ring groove can be done by preliminary pouring a layer of compound from below at the bottom of the groove, and then laying the tape on it.

Also, fastening of a metal or plastic tape in a ring groove can be done by preliminary pouring a layer of compound from below at the bottom of the groove, followed by laying the tape and then re-pouring an additional layer of compound on top.

Preferably, a steel tape with a lock is used as a metal fastening tape.

The fastening using fastening tape and compound is made in such a way that the compound covers the tape by 1 mm.

Brief description of the drawings

Fig. 1 shows a diagram of a tape with a lock and marks installed inside, filled with compound;

Fig. 2, 3 show various geometries of railway wheels with grooves (A), a close-up of which is shown in Fig. 4;

Fig. 5, 6 show the wheel loading diagrams during the tests, respectively for the wheels of Fig. 2, 3;

Fig. 7 shows a general view of the endurance limit test of a wheel with a groove on the TsDM 200 PU-1 testing machine;

Fig. 8, 9 show the equivalent stresses in the wheel with a groove of the geometry of Fig. 2 (loading option No. 1), Pa: Fig. 8 - the wheel as a whole; Fig. 9 - the groove zone (σeqmax = 172 MPa);

Fig. 10, 11 show the equivalent stresses in the wheel with a groove of the geometry of Fig. 2 (loading option No. 2), Pa: Fig. 10 - the wheel as a whole; Fig. 11 - the groove zone (σeqmax = 249 MPa);

Fig. 12, 13 show the equivalent stresses in a wheel with a groove of the geometry of Fig. 2 (loading option No. 3), Pa: Fig. 12 - the wheel as a whole; Fig. 13 - the groove zone (σeqmax = 158 MPa);

Fig. 14, 15 show the equivalent stresses in a wheel with a groove of the geometry of Fig. 3 (loading option No. 1), Pa: Fig. 14 - the wheel as a whole; Fig. 15 - the groove zone (σeqmax = 156 MPa);

Fig. 16, 17 show the equivalent stresses in the wheel with a groove of the geometry of Fig. 3 (loading option No. 2), Pa: Fig. 16 - the wheel as a whole; Fig. 17 - the groove zone (σeqmax = 206 MPa);

Fig. 18-19 show the equivalent stresses in a wheel with a groove of the geometry of Fig. 3 (loading option No. 3), Pa: Fig. 18 - the wheel as a whole; Fig. 19 - the groove zone (σeqmax = 153 MPa);

Fig. 20 shows examples of the creation of prototypes of tapes with RFID tags filled with compound, which are still inside the forms fixed on the support;

Fig. 21 shows a finished working prototype of a ring belt with a lock and RFID tags filled with compound;

Fig. 22, 25 show prototypes of wheels with grooves, inside which tapes with RFID tags of various quantities (from 3 to 5 pieces) filled with compound are installed;

Fig. 26 shows an example of checking the functionality of RFID tags on a wheel;

Fig. 27 shows the layout of the UHF/RFID antennas at the experimental test site (top view);

Fig. 28 shows the layout of the UHF/RFID antennas at the experimental test site (side sectional view);

Fig. 29 shows a block diagram of the arrangement of equipment for automatic identification of wheel pairs;

Fig. 30 shows a histogram of read RFID tags at the registration post;

Fig. 31 shows a prototype for testing the frequency offset of an RFID tag located in the center of a copper substrate, compound on both sides;

Fig. 32 shows a prototype of testing the frequency offset of an RFID tag located in the center of a copper substrate, compound only at the bottom;

Fig. 33 shows a prototype for testing the frequency offset of an RFID tag located on the edge of a copper substrate, compounded on both sides;

Fig. 34 shows a prototype of testing the frequency offset of an RFID tag located on the edge of a copper substrate, compound only at the bottom;

Fig. 35 shows a test sample of frequency offset testing of RFID tag without copper substrate, compound on both sides;

Fig. 36 shows a prototype of testing the frequency offset of an RFID tag without a copper substrate, compound only on the bottom;

Fig. 37 shows the measuring complex;

Fig. 38 shows a diagram of reading a mark in air and on metal;

Fig. 39 shows a diagram of reading a mark on a copper substrate (center) surrounded by compound from below/above;

Fig. 40 shows a diagram of reading a mark on a copper substrate (at the edge) surrounded by compound from below/above;

Fig. 41 shows a diagram of reading a label without a substrate surrounded by a compound from below/above;

Fig. 42 shows the results of testing prototypes similar to those above, but with shifted frequency marks.

In the drawings: 1 - lock, 2 - RFID tag, 3 - annular groove, 4 - tape, 5 - compound, 6 - maximum groove depth, 7 - maximum groove width, 8 - minimum indent from the edge of the hub end face, 9 - minimum radius of curvature of the transition surface at the bottom of the groove, 10 - chamfers at an angle of 45°, 11 - wheel, 12 - wheel rim, 13 - fixed supports of the testing machine, 14 - rail, 15 - antenna, 16 - antenna contact wire, 17 - antenna mounting bracket to the rail, 18 - bracket mounting support unit, 19 - antenna plane indent from the rail running surface, 20 - RFID reader, 21 - computer, 22 - GSM modem, 23 - diagnostic post room.

Implementation of a utility model

Through many years of experimental testing, the optimal parameters for the location, width and depth of the annular groove were selected.

According to the utility model, the annular groove 3 (Fig. 4) is made with a depth 6 of no more than 8 mm, a width 7 of no more than 15 mm and with a distance 8 from the end of the wheel hub of no less than 20 mm, and also having a transition surface 9 from the walls to the bottom of the groove with a radius of curvature of no less than 2 mm, and identification marks in it are secured in the groove made using fastening tape 4 and compound 5 according to the declared solution.

That is, the maximum dimensions of the annular groove can be: depth - 8 mm, width - 15 mm, minimum distance from the end of the wheel hub - 20 mm, the presence of a transition surface from the walls to the bottom of the groove with a minimum radius of curvature of 2 mm.

Preferably, the upper edge of the hub surface is formed with a transition surface having chamfers with an angle of 45° or roundings.

It is precisely these optimal parameters of the location and geometry of the groove that ensure stable wheel durability and reduce the risk of cracks due to the groove.

As shown by the tests shown below, carried out on different wheel geometries (Fig. 2, 3), making the dimensions of the annular groove smaller, or removing it from the end of the hub at a greater distance, will help reduce stress.

Calculation schemes for loading wheel No. 1 (Fig. 2).

The calculation of the stress state for wheel No. 1 with such maximum groove parameters was carried out for three typical wheel loading options during operation as part of a wagon wheel pair:

1) movement of a wheelset along a straight section of track, when the wheels are mainly subjected to a vertical force (V1) along the rolling circle - Loading option No. 1;

2) movement of a wheelset in a curve, when a horizontal lateral force (L2) acts on the flange of one of the wheels, and a vertical force, shifted towards the flange (V2), acts on the rim - Loading option No. 2;

3) movement of a wheelset along a curved section of the track, when a vertical force acts on the outer (field) part of the rolling surface of the rim of one of the wheels (V3) - Loading option No. 3.

The mechanical load values are calculated based on the maximum static load from the wheel pair on the rails Q = 25 tf (245.0 kN). The vertical loads are considered as quasi-static, multiplied by the dynamic coefficient f = 3:

V1 = V2 = V3 = (f⋅Q/2)⋅g = 368 kN; L2 = 0.5⋅V2 = 184 kN.

The diagram of the application of loads to the rim 12 of the wheel 11 is shown in Fig. 5, 6, where 13 are the fixed supports of the testing machine (Fig. 7).

The stress state of the wheel for various variants of load application is presented in the form of equivalent stresses according to von Mises [MPa] - IV theory of strength:

,

where σ ₁ , σ ₂ , σ ₃ are the principal (circumferential, radial and axial) stresses.

The stress values arising at the points of load application were not considered due to the application of loads to the nodes of the finite element model. This caused a high stress concentration in the zone of load application to the rim and under it, therefore these zones were excluded from the analysis of the results.

Results of the calculation of the loading of wheel No. 1 (Fig. 2).

Fig. 8-13 shows the results of calculating the equivalent stress state of a wheel with a groove for three design loading schemes taking into account the mounting load when it is pressed onto the axle with interference. The values of the maximum equivalent stresses determining the fatigue endurance are presented in Table 1.

Table 1. Maximum equivalent stresses in a wheel with a groove.

Loading option Maximum equivalent stresses, MPa Ratio of maximum stresses in the wheel and in the groove zone Ratio of stresses in the groove zone to the yield strength of the wheel hub in the wheel
(generally) in the groove Loading along the rolling circle (option No. 1) 269 172 1.56 0.38 Loading in the ridge zone (option No. 2) 435 249 1.75 0.55 Loading at the outer zone of the rolling surface (option No. 3) 443 158 2.80 0.35

As can be seen from Fig. 8-13 and the data in Table 1, for all loading schemes, the maximum equivalent stresses in the wheel arise not in the groove zone, but in the rim (loading variants 2 and 3) or edge (loading variant 1) zones of the disk. A comparison of the equivalent stresses in the groove zone with the equivalent stresses acting in the wheel as a whole shows that the maximum stresses in the groove zone for all loading variants are significantly lower than the maximum stresses in the wheel as a whole. In this case, the safety factor for stresses in the groove zone, depending on the loading variant, is in the range of 1.6-2.8, i.e. no significant stress concentration occurs in the groove zone on the hub.

The maximum equivalent stresses occur in the groove zone under loading option 2 (movement of the wheelset in a curve) and amount to 249 MPa. According to the IV theory of strength, the safety criterion of the stress state from the point of view of crack occurrence is the value of equivalent stresses less than the yield strength of the material, i.e. σ _eq < σt. Considering that the yield strength of the metal of the hub of the T-brand wheel is ~450 MPa, the value of the maximum equivalent stresses in the groove zone is characterized by the ratio σ _eq = 0.67 _σt , which indicates the safety of this stress state.

Analysis of the results of strength calculation and assessment of the stress state of the wheel according to the parameters with a groove having dimensions according to the declared solution.

The calculation included finite element modeling of the stress state of a solid-rolled wheel made of grade T steel according to GOST 10791-2011 with the design and location of the groove according to the declared solution, having an annular groove in the hub according to TU 26.20.30-003-14199399-2023, subject to its operation as part of a wheelset of a freight car with a maximum static load from the wheelset on the rails of 25.0 tf.

The purpose of the calculation was to analyze the stress state in the wheel hub groove zone when applying a certain set of mechanical loads characteristic of the main operating modes of the wheel: movement along straight sections of the track and movement in curved sections of the track.

The methodology used in the calculations took into account operational loads with the addition of a dynamic component, as well as assembly loads caused by the wheel being fitted to the axle with interference when forming the wheel pair. The ANSYS automated engineering analysis suite was used as software for performing the calculations. Based on the calculation results, conclusions were made about the reliability of a wheel with a groove in the hub in terms of the safety factor for stresses and about the possibility of using a wheel of such a design in wheel pairs of railway rolling stock.

Description of the finite element model of wheel No. 2 (Fig. 3).

The wheel geometry was set in accordance with the nominal dimensions (Fig. 14). The analysis of the stress state of the wheel was carried out for the minimum values of the rim and hub thickness with an annular groove in the hub with a nominal depth of 8 mm (Fig. 15). Fig. 14 additionally shows (in blue) the dimensions necessary to take into account the wheel rim thickness of 22 mm, the minimum allowed in operation for freight car wheels, and to simulate the pressing of the wheel onto the axle with a maximum allowable interference of 0.25 mm in accordance with the requirements of RD VNIIZhT 27.05.01-2017.

Fig. 5 and 6 show a geometric model of the wheel and axle. A rigid fixture is used to secure the model to the axle ends.

The finite element model of a wheel with a groove, fixed on an axle, is shown in Fig. 7.

Due to the symmetry of the wheel design and the applied loads, a half-wheel model was used in the calculation with the corresponding conditions on the planes of symmetry. The discretization of the model was performed by eight-node finite elements - hexahedrons. The model size was about 350,000 elements. In the groove area, a more discrete grid was created with element sizes sufficient for the correct establishment of stress concentration values.

Calculation schemes of wheel No. 2 (Fig. 3).

The calculation of the stress state was carried out for three typical cases of wheel loading during operation as part of a wagon wheel pair:

movement of a wheel pair along a straight section of the track, when the wheels are mainly subject to a vertical force (V1) along the rolling circle - Loading option No. 1;

movement of a wheelset in a curve, when a horizontal lateral force (L2) acts on the flange of one of the wheels, and a vertical force, shifted towards the flange (V2), acts on the rim - Loading option No. 2;

movement of a wheel pair along a curved section of track, when a vertical force acts on the outer (field) part of the rolling surface of the rim of one of the wheels (V3) - Loading option No. 3.

Calculation results for wheel No. 2 (Fig. 3).

Fig. 14-19 show the results of calculating the equivalent stress state of wheel No. 2 with a groove for three design loading schemes taking into account the mounting load when it is pressed onto the axle with interference. The values of the maximum equivalent stresses determining fatigue endurance are presented in Table 2.

Table 2. Maximum equivalent stresses in a wheel with a groove.

Loading option Maximum equivalent stresses, MPa Ratio of maximum stresses in the wheel and in the groove zone Ratio of stresses in the groove zone to the yield strength of the wheel hub in the wheel
(generally) in the groove Loading along the rolling circle (option No. 1) 330 156 2.12 0.35 Loading in the ridge zone (option No. 2) 563 206 2.73 0.46 Loading at the outer zone of the rolling surface (option No. 3) 435 153 2.84 0.34

As can be seen from Fig. 14-19 and the data in Table 2, for all loading schemes, the maximum equivalent stresses in the wheel arise not in the groove zone, but in the rim (loading variants 1 and 3) or edge (loading variant 2) zones of the disk. A comparison of the equivalent stresses in the groove zone with the equivalent stresses acting in the wheel as a whole shows that the maximum stresses in the groove zone for all loading variants are significantly lower than the maximum stresses in the wheel as a whole. In this case, the safety factor for stresses in the groove zone, depending on the loading variant, is in the range of 2.1-2.8, i.e. no significant stress concentration occurs in the groove zone on the hub.

The maximum equivalent stresses occur in the groove zone under loading option 2 (movement of the wheelset in a curve) and are 206 MPa. According to the IV theory of strength, the safety criterion of the stress state from the point of view of crack occurrence is the value of equivalent stresses less than the yield strength of the material, i.e. σ _eq < σt. Considering that the yield strength of the metal of the T-brand wheel hub is ~450 MPa, the value of the maximum equivalent stresses in the groove zone is characterized by the ratio σ _eq = 0.67 _σt , which indicates the safety of this stress state.

Bench tests of a grooved wheel for fatigue endurance.

Bench tests of a wheel with a groove were carried out in order to confirm that the wheel's endurance limit complies with the requirements of paragraph 6.23 of GOST 10791-2011, taking into account the area of its application in wheel pairs with an axle load of 25 tf.

The wheel with the groove parameters according to the declared solution with a groove depth of 4 mm according to TU 26.20.30-003-14199399-2023 with an installed automatic identification kit was subjected to bench tests (according to the results of strength calculations, the wheel of this design is the most loaded in the groove zone). A used wheel with a rim thickness of 29 mm was selected for testing.

The test was carried out taking into account the methodological requirements of paragraph 8.11.1 of GOST 10791-2011 according to the diagram shown in Fig. 15. In this case, the wheel with a groove was installed vertically on the testing machine and a steel axle, the diameter of which was 2 mm smaller than the diameter of the wheel hub hole, was passed through the hub hole. The axle rested on two fixed profile supports of the testing machine.

The cyclic load during testing was applied in the radial direction to the wheel rim in accordance with the diagram in Fig. 15 (the point of application of the load to the wheel rolling surface was at a distance of 48 mm from the side surface of the rim on the inner side).

The test was carried out on a universal machine TsDM 200 PU-1, capable of providing a maximum cyclic load of up to 1000 kN and a frequency of cyclic loads within 4-10 Hz with an asymmetry coefficient of 0.1.

The magnitude and stability of the cyclic load during testing were monitored using the force-measuring devices of the testing machine. The absence of cracks in the wheel was monitored visually and using a kerosene sample without stopping the testing machine.

The wheel was tested until the base number of loading cycles (5 million cycles) was reached or until a fatigue crack of 20 mm or more in length was detected, whichever came first, with the number of loading cycles completed recorded.

The wheel was tested in two sections with a maximum cyclic load of 495 kN, which exceeds the minimum permissible fatigue limit of 450 kN in accordance with paragraph 6.23 of GOST 10791-2011. Upon completion of the tests, each of the two sections of the wheel with a groove passed the basic number of loading cycles without the formation of fatigue cracks.

Thus, based on the results of the bench fatigue tests, it was established that the minimum fatigue limit of the wheel with an annular groove in the hub according to the declared solution is 495 kN, which corresponds to the requirements of paragraph 6.23 of GOST 10791-2011 for an axle load of 25 tf. Considering that, according to the results of strength calculations, the wheel with the declared design is the most loaded in the groove zone, the results of bench tests obtained for it can be extended to the wheel with the design and groove in the hub.

Thus, the conducted study on calculating the strength of the axle wheel with a circular groove for 23.5 TC and 25 TC wheels indicates the safety of manufacturing this annular groove with maximum parameters according to the declared solution.

The fastening of automatic identification marks on a railway wheel is characterized by the execution of a ring groove in the area of the hub of the railway wheel, inside which identification marks are placed, which are covered with a layer of casting compound.

To prepare automatic identification means, a casting form is used (see Fig. 20), which repeats the shape of the groove in a railway wheel.

A tape 4 with a lock 1 (see Fig. 1) is placed in this form and stretched (see Fig. 20), for example, by securing it to a support.

Compound 5 is poured into the mold and identification marks 2 are placed.

Next, the foil antenna of each tag is bent toward the metallized base of the tag. In this case, the identification tag is positioned along the axis with the tape so that the tag chip is closer to the edge of the smallest side.

After the compound 5 has hardened, the formed ready (see Fig. 21) fastening tape 4 with the compound 5 and marks 2 is removed from the mold. Then the fastening tape 4 with the compound 5 and marks 2 is installed in the groove 3 of the railway wheel and its ends are fixed with the lock 1.

In this case, RFID radio frequency tags are used as identification tags 2, the operating frequency of which with a layer of compound applied on top is within the range of 863-868 MHz, which ensures the achievement of a result consisting in eliminating the problem of the impossibility of reading due to the use of compound and the installation of the radio frequency tag in a recess.

The claimed solution, in contrast to the prototype and other analogues, has the advantage of eliminating the problem of frequency shift of radio tags, which occurs when the tag is immersed in a groove and a compound is used to attach the tag and protect it from environmental influences.

The fastening of a metal or plastic tape in a ring groove is carried out by laying it and then pouring an additional layer of compound on top.

Also, fastening of a metal or plastic tape in a ring groove is carried out by preliminary pouring of a layer of compound from below at the bottom of the groove, and subsequent laying of the tape.

Also, fastening of a metal or plastic tape in a ring groove is carried out by preliminary pouring a layer of compound from below at the bottom of the groove, followed by laying the tape and then re-pouring an additional layer of compound on top.

Preferably, a steel tape with a lock is used as a metal fastening tape.

Fastening using fastening tape and compound is carried out so that the compound covers the tape by 1 mm.

Example 1 of filling a form.

Apply the first layer of compound to the mould over the tape and distribute it so that the compound covers the tape by 1 mm; after waiting at least 15 minutes, place the identification marks on the first layer of compound; then fill the mould with the second layer of compound, ensuring that the established geometry of each mark is maintained.

Example 2 of form filling.

Identification marks are placed on the tape laid in the form, after which they are covered with a layer of compound, ensuring that the established geometry of each mark is maintained.

Example 3 of form filling.

The first layer of compound is applied to the mold, then tape is placed on top, after which identification marks are placed; then the mold is filled with a second layer of compound, ensuring that the established geometry of each mark is maintained.

The principle of automation of the wheel identification process is as follows.

After recording the individual wheel number in the user memory of the tags and adding the individual axle number, the data is transferred to the relevant documents for the wheel pair using available radio frequency readers and software, thereby eliminating the possibility of providing inaccurate data due to the human factor. During operation, the tags can be registered at existing rolling stock technical condition monitoring posts, with the installation of additional stationary radio frequency readers available for purchase and the availability of software, allowing you to link technical parameters to a specific wheel pair, which is paramount for analyzing the pre-failure condition of the wheel pair. Also, this system allows repair companies to significantly reduce financial costs when repairing a wheel pair by implementing information and digital systems for managing production and repair processes.

Reliable identification of wheel pairs using the specified technical solution, means of reading information on the road network and enterprises, and their interaction with the Information Base of the interstate level, are capable of forming a common system of accounting and tracking information on wheel pairs and its elements.

The technical effect associated with increasing the reliability of the fastening of the automatic control and number accounting system on railway transport is achieved by using a combined fastening using a metal or plastic tape and compound, which provides a safety margin during deformation and vibration. The technical effect associated with eliminating the problem of inaccuracy of reading due to the use of only compound for fastening is achieved by using radio tags with a reduced frequency, the frequency of which in the working state with a coated layer of compound shifts to 863-868 MHz and can be read by standard devices permitted in the Russian Federation for free use.

As noted earlier, there is a problem of RFID tag frequency shift that occurs when the tag is immersed in a groove and a compound is used to attach the tag and protect it from environmental influences (the same epoxy resin). It leads to the impossibility of reading due to the use of compound and installation of the RFID tag in a groove recess.

The problem is caused by a shift in the original frequency of standard radio tags in the 863-868 MHz frequency range.

This was revealed during testing of various variants of tape, tag and compound sets, where Confidex Silverline Slim II tags (4 pcs.) were tested. Measurements were made for the following cases:

The RFID tag is surrounded by compound from below/above and is glued to the center of the copper substrate (Fig. 31);

The RFID tag is surrounded by compound only from below and is glued to the center of the copper substrate (Fig. 32);

The RFID tag is surrounded by compound from below/above and is glued to the edge of the copper substrate (Fig. 33);

The RFID tag is surrounded by compound only from below and is glued to the edge of the copper substrate (Fig. 34);

The RFID tag is surrounded by compound from below/above, without a copper backing (Fig. 35);

The RFID tag is surrounded by compound only from below, without a copper backing (Fig. 36).

For all cases, the steel strip was closed, the diameter of the resulting circle was 250 mm.

The measuring complex (see Fig. 37) included a Voyantic device with a power of P=2 W, a frequency of f=800-1000 MHz, and linear polarization of the antenna.

The measurement results are shown in the diagrams in Fig. 38-41, where the dependences of the reading distance of the marks are displayed.

From the diagram in Fig. 38 it is evident that the Confidex Silverline II tag has a pronounced resonance peak at a frequency of 860 MHz and a reading distance in the air of 4.5 m and on metal of 6.5 m. And from other diagrams (Figs. 39-41) it follows that the compound, especially the upper layer located above the tag, has a strong effect on its frequency response, shifting it to the low frequency region. As a result, the resonance peak shifts by 40-50 MHz and the tag reading distance decreases several times. The Confidex Silverline II tag, like any other RFID tags, is designed to work on metal surfaces, therefore the copper substrate located under it provides a 1.5-fold increase in the reading distance. The shift of the tag along the copper substrate does not have a significant effect on the tag's frequency response.

Thus, the results of these studies clearly demonstrate the existence of a problem of RFID tag frequency shift when it is filled with compound.

To eliminate this problem, it was decided to use RFID tags with a frequency of 980 MHz as identification tags.

The use of RFID tags with a frequency within 980 MHz gave the desired result of the output operating frequency from under the compound layer within 863-868 MHz.

The results of testing prototypes similar to those above, but with shifted frequency marks, can be seen in Fig. 42. They clearly demonstrate that the operating frequency is in the desired frequency range when the marks under the compound layer are in the groove of the wheel.

The marks are fixed in the annular groove using metal or plastic fastening tape and casting compound. Moreover, the fixing can be done in various ways.

The first option is a method of fastening, when marks are first installed in the annular groove using metal or plastic tape, after which a layer of compound is applied on top to protect against mechanical and climatic influences.

The second option is a method of fastening, when first the compound is poured into the annular groove, and the marks are attached on top using metal or plastic tape.

The third option is a method of fastening, in which, first, compound is poured into the annular groove, after which the marks are attached using metal or plastic tape, and then the compound is poured again.

Moreover, the tapes can have different form factors and locks.

Various room temperature curing casting compounds can be used as compounds.

For example, the casting compound Silant EPI-222 KE2-222, UNIFIKS compounds (https://npfatlas.ru/catalog/384/), and STEP compounds can be used.

The utility model is illustrated by an example.

For the production of a railway wheel with the possibility of automatic identification, having a ring groove in the hub area, inside which identification marks are installed and filled with compound, the following set of objects and substances is used, for example:

A specialized casting mold that replicates the shape of a groove in a railway wheel with associated hardware;

Set of spatulas for applying epoxy resin;

Modernized gun KVT TG-05 for tightening steel tape;

- Steel tape with a lock 4.6×1000 mm (Steel ties FORTISFLEX SKS 304 4.6×1000 74918);

Release wax spray (optional);

Spatula (several pieces);

Measuring scales;

Degreaser;

STEP-3K9 compound;

RFID tag Z13100M-3DC.

The declared method of attaching automatic identification marks to a railway wheel is carried out in the following stages:

1. Assemble a specialized pouring form and secure it to a flat surface.

2. Clean the surface of the mold and degrease it.

3. Apply release wax and wait until dry.

4. Insert the steel tape with the lock into the mold: fix the tape with the side with the lock into the mold; tighten the tape with the modernized tightening gun (low force) and fix the other end in the mold.

5. Apply the compound to the mold, in small quantities over the steel tape, and spread it with a specialized spatula so that the compound covers the steel tape by 1 mm (the size is provided by the tool).

6. After 15 minutes, place the RFID tags on the first layer of compound, while: bending the foil antenna to the metallized base of the tag; positioning the RFID tag along the axis with the steel tape so that the tag chip is closer to the edge of the smallest side.

7. After 15 minutes, fill the form with compound, distributing it with a specialized spatula and ensuring the geometry of the mark.

8. After hardening, inspect the quality of the compound and, if necessary, fill it locally.

9. Disassemble the fastening to the form and carefully remove the tape with marks and compound.

10. Remove traces of compound from the edges.

11. Check the functionality of RFID tags (see example in Fig. 26).

12. Clean the mold from traces of compound.

Installation of formed tape with marks and compound on a 25 TS and 23.5 TS railway wheel.

For the installation operation on a railway wheel you will need:

Degreaser;

STEP-3K9 compound;

Measuring scales;

Spatula;

Modernized gun KVT TG-05 for tightening steel tape;

Side cutters.

Installation operations:

1. Degrease the surface of the wheel groove and let it dry.

2. Apply a thin layer of compound either into the wheel groove or onto the underside of the tape.

3. Insert the formed tape (see Fig. 21) into the groove, while inserting the end of the steel tape into the lock (for a 23.5 TC wheel, remove excess compound with side cutters).

4. Using a modified steel band tightening gun, tighten the band into the groove.

5. Bite off the steel strip flush with the lock.

6. Remove all excess compound that was squeezed out during tightening.

7. Pour the compound into the place where the lock is located, shape the groove with a spatula, and remove the excess.

8. Check the functionality of the tags.

Testing of finished wheels with a groove and a tape with RFID tags and compound installed inside it, according to the declared solution.

The objects of the tests were prototypes (Fig. 22-25) of automatic identification kits for railway wheels, equipped with a bundle of three to five RFID tags in the place of the technological groove along the diameter of the wheel hub. The places of installation of the tags were preserved and painted for the purpose of protection from external mechanical impacts and climatic impacts of the environment.

Number of test objects: four wheels with tags (two with three tags and two with five RFID tags as part of two wheels placed on two wheel pairs on the side of the receiving floor UHF/RFID antennas 15 (Fig. 27, 28) in the configuration of one bogie of the experimental gondola car.

Antennas 15 (see Fig. 27) were attached with an indentation 19 of their plane from the rolling surface of rail 14. The antennas 15 were attached using brackets 17, which were fixed to support unit 18, which, in turn, was installed with an emphasis on rail 14.

Antenna 15 was connected by means of contact wire 16 to RFID reader 20 (see Fig. 29), which was already located inside diagnostic post room 23, located at a certain distance from the track. RFID reader 20 was connected to computer 21, which, through connection with GSM modem 22, had the ability to wirelessly transmit data via the Internet to a remote monitoring node for collecting information (not shown).

The purpose of the tests was to evaluate the performance of the method for automatic identification of wheel pairs while the train is moving (while the car is moving).

The objectives of the tests were to determine the optimal option for equipping the cars with RFID tags, ensuring stable reading of the radio signal at a speed of at least 70 km/h, as well as to determine the operability of the method for automatic identification of wheel pairs under conditions of serviceable RFID equipment when a gondola car passes a section of the track equipped with UHF/RFID antennas, when recognizing the conditional serial number of each wheel.

The technical characteristics of the investigated wheels with tags according to the declared solution, RFID tags and the tape on which the RFID tags were placed are respectively given in Tables 3 - 5.

Table 3. Technical characteristics of the prototype railway wheel with a groove and tapes with RFID tags installed inside it, filled with compound.

Model TU 0943-002-14199399-2017 Designated service life 15 years Assigned resource 10 years Maximum range of radio signal reading up to 2 m Operating temperature -60°C...+40°C Operating frequency range UHF (865-869 MHz) Memory capacity EPC: 128 bit; User: 512 bits; TID: 96 bits

Table 4. Technical characteristics of RFID tags

Model Confidex Silverline Slim Manufacturer Confidence Label type passive Type of object to be marked metal Operating frequency range UHF (865-869 MHz) Maximum reading range up to 4 m Operating temperature -35°C...+85°C Size 110 x 13 x 0.8 mm Radio interface protocol EPCGlobal Classi Gen2 ISO 18000-6C Memory capacity EPC: 128 bit; User: 512 bits; TID: 96 bits Protection class IP68

Table 5. Technical characteristics of the tie-down strap with a lock

Model UHH31-D088-1000-100 Manufacturer IEK Product material metal Size 1000 x 8.8 mm Protection class IP20 Operating temperature -40°C...+70°C

To evaluate the performance of a railway wheel with a groove and a tape with RFID tags installed inside it, filled with compound, and to record signals coming from RFID tags, experimental equipment was used, including stationary hardware (Fig. 29):

three stationary (floor) UHF/RFID antennas 15, placed on one side of the railway track to recognize the wheels on one side of the car;

RFID reader 20 (reading device);

personal computer 21, designed to accumulate and store primary information received from the GPS/GLONASS tracker about the coordinates and speed of movement of the test car and from the unique numbers (EPC) of RFID tags, as well as processing this information and providing it to users in the form of final test results protocols;

GSM modem 22 connected to the computer;

experimental (trial) software.

During tests on the experimental ring of JSC VNIIZhT, a freight train, which included an experimental gondola car with wheel pairs equipped with tags installed in the annular groove of the wheels in accordance with the declared solution, periodically passed through the RFID tag registration post (location of floor UHF/RFID antennas) at a speed of up to 70 km/h inclusive.

The tests were suspended if ten or more consecutive cases of failure to register a signal from RFID tags of a specific wheel were detected during a shift.

The specified number of passes of the experimental gondola car through the registration post until the full completion of the tests in accordance with the test program and methodology was at least 2000 units.

During the tests, which included 2066 passes through the RFID tag radio signal registration post, not a single case of an unrecognized wheel was recorded, i.e. during the tests, at each pass for each wheel equipped with a tag, the unique number (EPC) of at least one RFID tag was read and identified.

Table 6 shows the results of calculations of the theoretical probability of wheel recognition in the case of its assembly with a different number of RFID tags (from 3 to 5 pieces), which were obtained based on the results of running a gondola car in 2066 passes.

Table 6. Probability of recognition (identification) of the wheel for different
number of RFID tags.

Name of the indicator Number of RFID tags in the tape (pcs.) 3 4 5 Wheel recognition probability, % 99.76 99.97 99,996

It follows from Table 6 that for the option of three RFID tags, the calculated value of the performance indicator in the form of the probability of recognition (identification) of the wheel, although it does not correspond to the value equal to 99.9%, declared in the program and test methodology, but in the case of installing antennas 18 on both sides of the track, and tags on both wheels of the pair, the probability already corresponds to the value of 99.9%. This conclusion allows us to talk about the possibility of reducing the number of RFID tags per wheel to three, provided that they are installed on both wheels of the wheel pair, and also provided that they are read by antennas on both sides of the track.

Table 7. Relative read frequencies of tested RFID tags.

No.
pp Unique RFID tag number Relative RFID tag reading frequency 1. 00003000 0.90 2. 00003001 0.86 3. 00003002 0.90 4. 00003003 0.89 5. 00003004 0.88 6. 00004000 0.87 7. 00004001 0.76 8. 00004002 0.80 9. 00004003 0.92 10. 00004004 0.88 Average frequency (equivalent to p) 0.87

From Table 7 it follows that the values of the relative reading frequencies of RFID tags have deviations from the average frequency.

In order to understand whether these deviations are natural (random) or whether there is an influence of a specific prevailing factor, Table 8 provides generalized factual data on the distribution of relative frequencies and probabilities of simultaneous reading of a given number of RFID tags when passing through the registration post.

Table 8. Relative frequencies and probabilities of reading a given number of RFID tags when passing through a registration post.

No. pp Number of RFID tags read simultaneously during passage Relative frequency of reading a given number of RFID tags during passage (actual data) Probability of reading a given number of RFID tags during passage (theoretical data) 1. 0 0 0,00004 2. 1 0.01 0,0014 3. 2 0.04 0,018 4. 3 0.11 0.12 5. 4 0.28 0.38 6. 5 0.56 0.49

Fig. 30 shows a histogram comparing the relative frequencies and probabilities of reading a given number of RFID tags when passing through a radio signal registration post.

From Table 8 and Fig. 30 it is evident that there is a discrepancy between the actual frequency distribution and the theoretical probability distribution of simultaneous reading of a given number of RFID tags during each pass through the radio signal registration post.

To assess the degree of this discrepancy, and, consequently, to form conclusions about the mutual correspondence (discrepancy) between the theoretical and actual distributions, calculations were carried out, the results of which are contained in Table 9.

Table 9. Actual and theoretical distribution of a given number of simultaneously read RFID tags based on 2066 passes.

No. pp Number of RFID tags read simultaneously during passage Actual number of readings based on 2066 passes Theoretical number of reads per 2066 passes 1. 0 0 0.088 2. 1 25.5 2.86 3. 2 83.5 37.05 4. 3 229 240.07 5. 4 570.5 777.84 6. 5 1157,5 1008.09

The results in Table 9 show that the distribution of actual frequencies and probabilities of the random variable (the number of simultaneously read RFID tags) are not mutually consistent with each other.

From which it followed that the reason for the deviations in the number of simultaneously read RFID tags when passing through the registration post is the dependence of the reception of RFID tag signals on each other and/or on the individual features of RFID tags (deviations in their technical characteristics), arising as a result of manufacturing tolerances or manifested in their mutual arrangement in the wheel.

In order to analyze the influence of the serial numbers of wheel pairs (the sequence of the arrangement of wheel pairs along the direction of travel) equipped with tags on the results of wheel recognition, studies were conducted, the results of which on the results of reading RFID tags separately for the wheel pair with the conventional number No. 1 and the wheel pair No. 2 are presented in Table 10.

Table 10. Distribution of received and unreceived radio signals of RFID tags on individual wheels of experimental wheel sets.

Conventional number of a wheel pair (wheel) with marks Total number of received radio signals of RFID tags during the testing period, units / % Total number of unreceived RFID tag radio signals during the testing period, units / % Wheel pair #1 (wheel #1) 9155 / 51 1175 / 43 Wheel pair #2 (wheel #2) 8743 / 49 1587 / 57 Grand total 17898 / 100 2762 / 100

Table 10 shows that wheel No. 1 accounts for 51% of all RFID tag radio signal readings during the testing period, compared to 49% for wheel No. 2. The distribution by the number of RFID tag radio signals not received is as follows: for wheel No. 1 - 43%, for wheel No. 2 - 57%.

The results of this analysis showed that the total number of passes through the radio signal registration post, accompanied by the maximum number of simultaneously read RFID tags in the range of 4 - 5 units, when recognizing wheel No. 1 is greater than for wheel No. 2 by almost 10%, and for wheel No. 2, on the contrary, the total number of passes with the minimum number of read RFID tags in the range of 1 - 3 units is greater by 10% compared to wheel No. 1.

As a result, there is an uneven distribution of the share of RFID tag readings depending on the serial number of the wheel pair (the sequence of the wheel pairs along the train’s movement).

In addition, these results indicate a slight decrease in the quality of reading radio signals of RFID tags as the ordinal number of wheel pairs increases. In this case, the quality of reading radio signals is understood as the completeness of reading RFID tags from zero to five RFID tags.

The above gave grounds to assert that the quality of wheel recognition may decrease or fluctuate as a train passes the radio signal registration post, the wheelsets of whose carriages are equipped with marks.

Therefore, it is advisable to equip both wheels of the pair with marks, as well as to install antennas 15 on both sides of the track.

In accordance with the test conditions, four wheels on one side of the bogie of four wheel pairs of the experimental gondola car were equipped with sets of marks in quantities of 3 to 5.

The test results confirmed the operability of the method for automatic identification of wheel pairs while the train is moving, provided that the RFID equipment and its reading system are in good working order when the gondola car passes a section of the track equipped with UHF/RFID antennas.

Based on the results of tests on a limited number of passes through the RFID tag radio signal registration post, equal to 2066 units, the actual share of recognition of conventional wheel numbers was 100%.

During the tests, a shift in the operating frequency of RFID tags from 980 MHz (the frequency of the tag itself during direct open use) was also recorded.

For this purpose, wheel pairs with marks were tested without a wagon for speed, rotating each of them on a test bench.

The RFID radio frequency tags of the four wheel pairs of the gondola car, installed inside the annular groove of one of the wheels of the pair with a layer of compound applied on top, had an operating frequency within 863 2024111336 868 MHz depending on the speed of the wheels (from 0 to 150 km/h).

Thus, by installing RFID tags with a shifted frequency under the compound layer, it was possible to eliminate the problem of the impossibility of reading tags with standard reading means, since the working frequency of the tags was already in the range of 863-868 MHz.

Claims (12)

1. A railway wheel having an annular groove in the hub area, where the groove has a transition surface from the walls to the bottom of the groove, characterized in that the annular groove is made with a depth of no more than 8 mm, a width of no more than 15 mm and with a distance from the end of the wheel hub of no less than 20 mm, and also has a transition surface from the walls to the bottom of the groove with a radius of curvature of no less than 2 mm. 2. A railway wheel according to item 1, characterized in that at least three identification marks are secured inside the groove using a fastening tape with a lock and compound. 3. A railway wheel according to item 2, characterized in that RFID radio frequency tags are used as identification tags, the operating frequency of which with a layer of compound applied on top is in the range of 863–868 MHz. 4. A railway wheel according to item 2, characterized in that RFID radio frequency tags with a frequency within 980 MHz are used as identification tags. 5. A railway wheel according to item 1, characterized in that the upper edge of the hub surface is made with a transition surface having chamfers with an angle of 45° or roundings. 6. A railway wheel according to item 2, characterized in that RFID radio frequency tags with the ability to read information from them at a speed of up to 150 km/h are used as identification tags. 7. A railway wheel according to claim 2, characterized in that the identification marks are placed between two layers of compound, where the marks are located along the axis with the tape so that the mark chip is closer to the edge of the smallest side of the wheel. 8. A railway wheel according to item 2, characterized in that the fastening of the metal or plastic tape in the annular groove is accomplished by pouring an additional layer of compound on top. 9. A railway wheel according to item 2, characterized in that the fastening of a metal or plastic tape in the annular groove is carried out by preliminary pouring a layer of compound from below at the bottom of the groove and subsequent laying of the tape on it. 10. A railway wheel according to item 2, characterized in that the fastening of a metal or plastic tape in the annular groove is carried out by preliminary pouring a layer of compound from below at the bottom of the groove, followed by laying the tape and then re-pouring an additional layer of compound from above. 11. A railway wheel according to item 2, characterized in that a steel tape with a lock is used as a metal fastening tape. 12. A railway wheel according to item 2, characterized in that the fastening using a fastening tape and compound is made such that the compound covers the tape by 1 mm.