Groove type steel rail fatigue test detection auxiliary loading device

Abstract

The utility model provides a trough type steel rail fatigue test detection auxiliary loading device which is provided with a buckling and pressing base plate. The buckling and pressing base plate is provided with a horizontal part, a hook part and a protruding block part which are integrally formed. The hook part and the bump part are arranged at the bottom of the horizontal part, the hook part is arranged on the outer side of the horizontal part, and the bump part is arranged in the middle of the horizontal part; the hook part wraps the outer edge of a rail head of the groove type steel rail from the outer side and is attached to and matched with the outer edge of the rail head. The protruding block part imitates the rail wheel to be contained in the rail head groove. And an inner concave molded surface formed by the convex block part and the hook part is fitted and matched with a rail head tread. The utility model solves the technical problem of how to eliminate the influence of the horizontal force on the oil cylinder of the testing machine by the trough-type steel rail; the problem that the loading center moves in the direct loading process is solved; damage to equipment and the oil cylinder body caused by shaking of the steel rail in the test process is reduced; and the safety risk in the fatigue test detection process of the channel steel rail is reduced.

Description

Technical Field

[0001] The utility model belongs to the technical field of physical measurement and testing of mechanical stress and testing of solid materials, and in particular relates to an auxiliary loading device for fatigue testing of grooved rails. Background Art

[0002] In recent years, my country's wheel-rail trains have developed rapidly in three aspects: high-speed passenger transport, heavy-load freight transport and urban rail transit. At the same time, important progress has been made in basic research, technical breakthroughs, product development, etc. Urban trams have become a highlight of the construction of first- and second-tier cities in my country. The grooved rails in urban rail transit have a slope on the rail head instead of the rail bottom slope of ordinary rails to increase wheel-rail matching and operation stability, reduce wear, and the grooved rail head has a U-shaped groove to protect the wheel rim, and the U-shaped groove of the grooved rail can make the track and the road surface have better integrity.

[0003] At present, most of the newly built modern tram track systems in my country use 59R2 or 60R2 grooved rails. "YB / T4653-2018 Urban Tram Grooved Rails" regulates the production and manufacturing of these two types of rails.

[0004] The stress state of grooved rails in actual urban rail structures is relatively complex. Without considering the influence of curves, switches and rail bottom slopes, the contact surface between the wheel flange curved surface tread and the grooved rail will change with the increase of wear (such as Figure 1 As shown in the figure, since the load centerline F does not pass through the centroidal principal axis YY of the grooved rail, the grooved rail component is in a complex stress state. However, when inspecting the product quality of the grooved rail or welded grooved rail component, we hope that the specimen can be in a simple stress state, which is conducive to the standardization and accuracy of the inspection process and conclusions.

[0005] The national standards CECS 429-2016 Urban Track Flash Welding Quality Inspection Standard for Grooved Rails, TB / T1632.1-2014 Welded Rails Part 1 General Technical Conditions, and TB / T1632.2-2014 Welded Rails Part 2 Flash Welding give the stress state of grooved rails or welded grooved rails in the quality inspection test, which is expressed as the following formula: Formula 1 requires that the specimen is in a plane stress state, and the load principal axis coincides with the specimen centroid principal axis, and the specimen is in a transverse force three-point bending state, where F is the vertical rail top surface load (the line of action passes through the principal axis centroid). Ideally, the load should pass through the centroid principal axis YY of the section, but it is often difficult to achieve in actual tests; because the top surface of the grooved rail is a curve and has a slope of 1 / 40, when the test machine pressure head is directly pressed on the tread of the rail, the load is eccentric and there is a horizontal force; when the upper end of the cylinder is fixed and constrained, and the bottom plate of the rail is also fixed and constrained, the horizontal force will be applied to the test machine pressure head and the cylinder and balanced with it, which will have an adverse effect on the test machine, so it is necessary to try to eliminate the influence of the horizontal force on the test machine cylinder, and it is necessary to design a new fatigue test pressure head to meet the needs of the test. In this regard, the following technical solution is proposed. Utility Model Content

[0006] The utility model solves the technical problem of providing an auxiliary loading device for fatigue test of grooved rails, solving the technical problem of how to eliminate the influence of horizontal force of grooved rails on the oil cylinder of a testing machine.

[0007] The utility model adopts the following technical scheme: an auxiliary loading device for fatigue test of grooved rail, which is provided with a buckling pad; the buckling pad has an integrally formed horizontal portion, a hook portion and a convex block portion; the hook portion and the convex block portion are arranged at the bottom of the horizontal portion, and the hook portion is arranged at the outside of the horizontal portion, and the convex block portion is arranged in the middle of the horizontal portion; the hook portion wraps the outer edge of the rail head of the grooved rail from the outside and fits closely with the outer edge of the rail head; the convex block portion imitates a rail wheel and is inserted into a rail head groove; the concave surface formed by the convex block portion and the hook portion fits closely with the rail head tread.

[0008] In the above technical solution, further: it also includes a testing machine pressure head, and the bottom of the testing machine pressure head is convex and concavely positioned and adapted to the top of the buckling pad.

[0009] In the above technical solution, further: a docking groove I is formed on the upper end surface of the testing machine pressure head; the testing machine action head is positioned, fitted and buckled with the docking groove I; and the center line of the testing machine action head coincides with the center line of the testing machine pressure head.

[0010] In the above technical solution, further: a docking groove II is formed on the upper end surface of the buckling pad; the testing machine pressure head is positioned, fitted and buckled with the docking groove II; the center line of the testing machine pressure head coincides with the center line of the buckling pad.

[0011] In the above technical solution, preferably: the material grade of the buckling pad is consistent with or better than the grade of the grooved rail.

[0012] In the above technical solution, preferably: the buckling pad is a buckling pad that has been subjected to a quenching and heat treatment and a surface carburizing treatment.

[0013] The advantages of this utility model compared with the prior art:

[0014] 1. The utility model solves the problem of movement of the loading center during direct loading.

[0015] 2. The utility model reduces the damage to the equipment and the oil cylinder body caused by the shaking of the rail during the test.

[0016] 3. The utility model reduces the safety risks during the fatigue test of grooved rails. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the longitudinal section of the grooved rail of the utility model;

[0018] Figure 2 This is the front view of the auxiliary loading device for fatigue testing of grooved rails of the utility model;

[0019] Figure 3 for Figure 2 Side view of auxiliary loading device for grooved rail fatigue test;

[0020] Figure 4 This is a front view of the buckling pad in the auxiliary loading device for fatigue testing of grooved rails of the utility model;

[0021] Figure 5 for Figure 4 Stereoscopic diagram of buckling pad;

[0022] Figure 6 This is a buckling force principle diagram of the buckling pad of the utility model;

[0023] Figure 7 It is the overall finite element cloud diagram of the grooved rail under static load state;

[0024] Figure 8 It is the overall finite element cloud diagram of the grooved rail under the action of pulsating load;

[0025] Fig. 9 It is the overall finite element cloud diagram of the grooved rail with buckling pad under the static load state;

[0026] Fig.10 The finite element overall cloud diagram of the grooved rail with buckling pad under pulsating load;

[0027] In the figure: 1-groove rail, 11-outer edge of rail head, 12-groove of rail head, 13-tread of rail head; 2-buckle pad, 21-horizontal part, 22-hook part, 23-bump part, 24-joint notch II; 3-testing machine pressure head, 31-joint notch I. DETAILED DESCRIPTION

[0028] The following will be combined with the attached embodiment of the utility model Figure 1-10 , clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of them. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0029] (like Figures 2 to 5 A groove rail fatigue test auxiliary loading device is shown, which has a buckling pad 2; the buckling pad 2 has an integrally formed horizontal portion 21, a hook portion 22 and a convex block portion 23. The integrally formed structure has high structural strength, ensures pressure-bearing rigidity, and has no deformation effect.

[0030] The hook portion 22 and the protrusion portion 23 are arranged at the bottom of the horizontal portion 21, and the hook portion 22 is arranged on the outside of the horizontal portion 21, and the protrusion portion is arranged in the middle of the horizontal portion 21. The hook portion 22 wraps the outer edge 11 of the rail head of the grooved rail 1 from the outside and fits snugly with the outer edge 11 of the rail head. The protrusion portion 23 imitates the rail wheel to be inserted into the rail head groove 12; the concave surface formed by the protrusion portion 23 and the hook portion 22 fits snugly with the rail head tread 13. The purpose is that the buckling pad 2 and the grooved rail 1 are embedded as a whole, and they will be tightly combined with the increase of load. The acting force between the inclined surface of the grooved rail 1 and the buckling pad 2 becomes an internal force, and the external load can pass vertically through the centroid principal axis YY of the grooved rail 1.

[0031] In the above embodiment, further: it also includes a testing machine pressure head 3, the bottom of the testing machine pressure head 3 is adapted to the convex and concave positioning of the top of the buckling pad 2, laying a foundation for the centering positioning described later.

[0032] In the above embodiment, further: the upper end surface of the testing machine pressure head 3 is formed with a docking groove Ⅰ31; the testing machine action head is positioned, fitted, buckled and adapted with the docking groove Ⅰ31; the center line of the testing machine action head coincides with the center line of the testing machine pressure head 3.

[0033] Similarly: In the above embodiment, further: the upper end surface of the buckling pad 2 is formed with a docking groove II24; the testing machine pressure head 3 is positioned, fitted and buckled with the docking groove II24; the center line of the testing machine pressure head 3 coincides with the center line of the buckling pad 2.

[0034] The purpose is that the testing machine pressure head 3, the buckling pad 2, and the testing machine actuator are all designed with a docking notch structure to ensure the centering of the three positioning installations.

[0035] In the above embodiment, preferably: the material grade of the buckling pad 2 is consistent with or better than the grade of the grooved rail 1. In the above embodiment, preferably: the buckling pad 2 is a buckling pad that has been subjected to quenching and tempering heat treatment and surface carburization treatment to increase the wear resistance of the buckling pad 2.

[0036] The utility model relates to a grooved rail fatigue test detection method, including a grooved rail fatigue test detection auxiliary loading device, comprising the following steps:

[0037] (like Figure 7 , Figure 8 As shown) Step 1: Perform a finite element analysis of the stress on the grooved rail 1 without the auxiliary loading device for the grooved rail fatigue test.

[0038] In the above embodiments, preferably, the force finite element analysis software is Abaqus finite element analysis software.

[0039] like Figure 7 As shown in the figure, the Abaqus finite element analysis software is used to establish a model for the grooved rail 1; the model has a total of 37388 nodes and a total of 28242 units, including 25002 C3D8R linear hexahedral units and 3240 C3D8I linear hexahedral units, the material is U75V, and the elastic modulus is E=210×10 9 GPa, Poisson's ratio is 0.3, the maximum tensile stress at the rail bottom is 304.9MPa, the theoretical calculation is 297MPa, and the relative error is 2.4%.

[0040] like Figure 8 As shown: the pulsating sine curve applied to the grooved rail, the curve is generated by the sine wave generator, the load frequency is 5Hz±0.5Hz; when the load ratio r=0.2, the actual load applied to the specimen is the actual load value assigned by the software, the actual load peak value is 350kN, and the load valley value is 70kN.

[0041] Figure 7 and Figure 8 Comparing the finite element cloud diagrams, the stress level and stress distribution patterns are consistent, indicating that the static and dynamic calculation results are consistent.

[0042] (Combined Figure 2 , Figure 3 ) Step 2: Put the buckling pad 2 in the auxiliary loading device for fatigue test of grooved rail on the grooved rail 1. Buckle the test machine action head on the test machine pressure head 3. Make the force action line of the test machine pressure head 3, the buckling pad 2, and the grooved rail 1 coincide with the force action line of the test machine oil cylinder, and the buckling pad 2 and the grooved rail 1 are embedded as a whole. The action force between the inclined surface of the grooved rail 1 and the buckling pad 2 becomes an internal force; make the external load pass vertically through the centroidal principal axis of the grooved rail 1.

[0043] (like Fig. 9 , Fig.10 Step 3: Perform a finite element analysis of the stress on the grooved rail 1 with an auxiliary loading device for grooved rail fatigue test.

[0044] (like Fig. 9 The test model of the grooved rail with buckling pad under static load is as follows Fig. 9 The model has a total of 64320 nodes and 46006 units, including 32202 C3D8R linear hexahedron units, 9450 C3D8I linear hexahedron units, 3150 C3D10M linear hexahedron units, and 1204 RNODE3D linear column units. The test machine head 3 at the top of the model is set as a rigid body and does not participate in deformation. The material of the grooved rail 1 is U75V, and the elastic modulus is E=210×10 9 GPa, Poisson's ratio 0.3.

[0045] (like Fig.10 (shown) is the overall finite element cloud diagram of the grooved rail buckling pad system under pulsating load. The curve is generated by a sine wave generator with a load frequency of 5Hz±0.5Hz. When the load ratio r=0.2, the actual load applied to the specimen is the actual load value assigned by the software, with an actual load peak value of 350kN and a load valley value of 70kN.

[0046] Step 4: Analyze, compare, and verify the results of steps 1 and 3.

[0047] Figure 7 and Figure 8 Comparing the finite element cloud diagrams, the stress level and stress distribution patterns are consistent, indicating that the static and dynamic calculation results are consistent. Fig. 9 and Fig.10 Compared with the static finite element overall cloud diagram of the buckle pad 2 system, the stress level is consistent, indicating that the static and dynamic calculation results are consistent. Figure 7 and Figure 8 In comparison, the corresponding dynamic stress levels and rules are the same, indicating that the designed buckling pad is effective and successful.

[0048] The working principle of this utility model: Figure 1 As shown in the figure, since the top surface of the grooved rail 1 has a certain slope, the rail shakes seriously during the fatigue test, and it is impossible to ensure that the load can act on the centroid axis YY of the grooved rail 1, and it is also impossible to ensure that the loading of the test machine pressure head 3 is not affected by the horizontal reaction force. Therefore, in order to reduce the rail shake of the grooved rail 1 during the fatigue test and solve the problems of the movement of the loading center and the inclination of the contact surface; the technical solution of the utility model is proposed: (as shown in the figure, Figure 2 , Figure 3 , Figure 6 As shown, the buckling pad 2 in the auxiliary loading device for fatigue test of the grooved rail 1 is used to form a whole with the rail head of the grooved rail 1 under the test load, which effectively solves the problem of the influence of the top slope of the grooved rail on the loading and the geometric asymmetry of the rail. The buckling pad 2 is used and directly mounted on the grooved rail 1. During the test and detection process, the test machine pressure head 3 directly acts on the upper surface of the buckling pad 2, and is transmitted through the buckling pad 2, and indirectly contacts the rail for testing. The contact surface of the buckling pad 2 simulates the wheel, and the load action line passes through the centroidal principal axis YY of the grooved rail 1, so that the force action line F of the test machine pressure head 3, the buckling pad 2, and the grooved rail 1 coincides with the force action line of the test machine cylinder, that is, the cylinder will not be subjected to an oblique reaction force, ensuring the normal operation of the cylinder. The test machine pressure head 3, the buckling pad 2, and the test machine actuator are all designed with docking notches to ensure the centering of the installation. The buckling pad 2 and the grooved rail 1 are inlaid as a whole, and will be tightly combined with the increase of load; the force between the inclined surface of the grooved rail 1 and the buckling pad 2 becomes an internal force, and the external load can pass vertically through the centroid principal axis YY of the grooved rail 1.

[0049] From the above description, it can be found that: the utility model solves the problem of movement of the loading center during direct loading; reduces the damage to the equipment and the cylinder body caused by the shaking of the rail during the test; and reduces the safety risks during the fatigue test of the grooved rail.

[0050] Each embodiment in this specification is described in a related manner, and the same or similar parts between the embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

[0051] The above description is only a preferred embodiment of the present invention and is not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims

1. An auxiliary loading device for grooved rail fatigue test, characterized in that: The invention provides a buckling pad (2); the buckling pad (2) has an integrally formed horizontal portion (21), a hook portion (22) and a convex portion (23); the hook portion (22) and the convex portion (23) are arranged at the bottom of the horizontal portion (21), and the hook portion (22) is arranged at the outside of the horizontal portion (21), and the convex portion is arranged at the middle of the horizontal portion (21); the hook portion (22) wraps around the outer edge (11) of the rail head of the grooved steel rail (1) from the outside and fits snugly with the outer edge (11) of the rail head; the convex portion (23) is inserted into the rail head groove (12) in imitation of a rail wheel; the concave surface formed by the convex portion (23) and the hook portion (22) fits snugly with the rail head tread (13).

2. The auxiliary loading device for grooved rail fatigue test according to claim 1, characterized in that: It also includes a testing machine pressure head (3); the bottom of the testing machine pressure head (3) is convexly and concavely positioned and adapted to the top of the buckling pad (2).

3. The auxiliary loading device for grooved rail fatigue test detection according to claim 2, characterized in that: The upper end surface of the testing machine pressure head (3) is provided with a docking notch I (31); the testing machine action head and the docking notch I (31) are positioned, fitted, buckled and adapted; the center line of the testing machine action head coincides with the center line of the testing machine pressure head (3).

4. The auxiliary loading device for grooved rail fatigue test according to claim 1 or 2, characterized in that: The upper end surface of the buckling pad (2) is provided with a docking notch II (24); the testing machine pressure head (3) is positioned, fitted and buckled with the docking notch II (24); the center line of the testing machine pressure head (3) coincides with the center line of the buckling pad (2).

5. The auxiliary loading device for grooved rail fatigue test according to claim 1 or 2, characterized in that: The material grade of the buckling pad (2) is consistent with or better than the grade of the grooved steel rail (1).

6. The auxiliary loading device for grooved rail fatigue test according to claim 1 or 2, characterized in that: The buckling pad (2) is a buckling pad that has been subjected to a quenching and tempering heat treatment and a surface carburizing treatment.

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