A structure of a 840 mm diameter steel wheel for a freight car

Abstract

A kind of truck wheel structure of rolling steel, including hub (1), spoke (2) and rim (3), it is characterized in that, wheel diameter is 840mm, the thickness of rim (3) is 60mm, the inner diameter of rim (3) is 720mm, the aperture of hub (1) is 210mm, overall weight is 314kg.The application increases the thickness of rim from 50mm of HESA wheel to 60mm under the premise of ensuring that the mass of wheel does not increase, which will not increase the unsprung mass, suitable for both 70t level truck, also can be used for 60t level truck.The relative HESA wheel of existing 70t level truck has the technical characteristics of high safety factor, light wheel weight, wide application range, and good application prospect.

Description

Technical Field

[0001] This utility model relates to the field of railway transportation technology, and in particular to a rolled steel wheel structure for freight cars with a diameter of 840mm. Background Technology

[0002] Railway freight cars are important transportation tools, capable of transporting large quantities of various goods, such as coal, ore, and grain, quickly and efficiently. They ensure energy supply, promote industrial and agricultural production, and facilitate regional economic exchange, playing a crucial role in socio-economic development and stabilizing the supply of goods. The wheels are key components of railway freight cars, bearing the weight of the car and generating friction with the rails to propel it forward, ensuring smooth and safe operation, and are essential for the normal transport of freight cars.

[0003] Most truck wheels in the United States are made of cast steel. According to AAR standards, truck wheels are classified by diameter into different sizes such as 28 inches, 30 inches, 33 inches, 36 inches, and 38 inches. Wheel types include A-28, E-28, A-30, J-33, M-33, P-33, H-36, J-36, K-38, B-38, C-38, and D-38. Rim thickness grades include 1.25 inches, 1.5 inches, 2 inches, and 2.5 inches, and rim thickness is classified into primary wear wheels, secondary wear wheels, and tertiary wear wheels. Under UIC standards, truck wheels are primarily rolled steel wheels, using secondary wear wheels, with a rim thickness of 50 mm.

[0004] Domestic railway freight car wheels are all secondary wear wheels, with a rim thickness of 50mm and a service life of 23mm. According to manufacturing processes, Chinese railway freight car wheels are divided into rolled steel wheels and cast steel wheels. Based on axle load, they are classified as 21-ton axle load type D wheels, 23(25)-ton axle load type E wheels, and 27(30)-ton axle load type F wheels. According to wheel model, rolled steel wheels mainly have three models: HDSA, HESA, and HFS, while cast steel wheels mainly have three models: HDZD, HEZD, and HFZ. According to wheel material, rolled steel wheels have three materials: CL60, CL65, and CL70, while cast steel wheels have two materials: ZL-B and ZL-C.

[0005] With the increasing axle load, higher operating speed, and harsher braking conditions, the safe use of wheels has become a major challenge. In recent years, the failure rate of E-wheel rim cracks in trucks has gradually increased, and the rim thickness is mostly near the limit when rim cracks occur.

[0006] The main reasons for the above problems are as follows:

[0007] First, the wheel rims of wheels E and D have the same thickness in their new manufacturing state and wear-to-limit state, and their axle loads are 25t and 21t respectively. During use, the wheel-rail contact stresses are different.

[0008] Secondly, the E-type rolled steel and cast steel wheels were designed with a 25t axle load in 2001 and 2003 respectively. Due to the limited design level and understanding of the operating conditions at that time, coupled with the low sensitivity of the flaw detection equipment, the safety margin at the design source was small and the tolerance for defects at the manufacturing source was poor.

[0009] Third, in recent years, with the increase in freight train speeds, the increase in the load per vehicle, and the increase in the traction tonnage of trains, the problem has become more prominent.

[0010] To reduce the probability of rim cracking, the operating department requires that the rim thickness be greater than or equal to 28mm during factory repairs, and mandates that wheel fasteners with rim flange thicknesses less than 25mm undergo focused inspection and risk assessment during train maintenance. These measures have, to some extent, shortened the service life of the wheels. From a technological development perspective, it is necessary to increase the rim thickness of wheels to improve their service life. Utility Model Content

[0011] To overcome the existing defects, this utility model proposes a rolled steel wheel structure for trucks with a diameter of 840mm.

[0012] A steel-rolled wheel structure for trucks with a diameter of 840mm includes a hub, spokes, and rim. The wheel diameter is 840mm, the rim thickness is 60mm, the rim inner diameter is 720mm, the hub bore diameter is 210mm, and the overall weight is 314kg. The overall structure features an S-shaped spoke design and an LM-shaped rim tread shape.

[0013] The spokes have an S-shaped structure and a thickness of 20 mm.

[0014] The wheel hub has an outer diameter of 286mm, a thickness of 38mm, and a width of 178mm.

[0015] The wheel rim width is 135mm and the inner hub rim distance is 68mm.

[0016] The main body of the spokes consists of two concentric circular arcs.

[0017] The angle range of the transition line from the rim to the inner and outer spokes is 1° to 20°. If the transition line segment is short, it can be fitted with a circular arc.

[0018] Preferably, the angles a and b of the transition line from the rim to the inner and outer spokes are 13° and 4°, respectively.

[0019] Preferably, the angles a and b of the transition line from the rim to the inner and outer spokes are 9° and 6°, respectively.

[0020] The angle range of the straight line transitioning from the hub to the inner and outer spokes is 1° to 20°. If the transition line segment is short, it can be fitted with a circular arc.

[0021] Preferably, the angles c and d of the transition line from the hub to the inner and outer spokes are 9° and 9°, respectively.

[0022] Preferably, the angles c and d of the transition line from the hub to the inner and outer spokes are 9° and 8°, respectively.

[0023] This application introduces a rolled steel wheel structure for trucks with a diameter of 840mm. Without increasing the wheel's weight, the rim thickness is increased from 50mm to 60mm (as in HESA wheels), without increasing the unsprung mass. It is suitable for existing 70t-class trucks and can also be used as a cover for 60t-class trucks. Compared to existing 70t-class truck HESA wheels, it features a higher safety factor and lighter wheel weight, has a wider range of applicable vehicle models, and shows promising application prospects. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of a steel rolling wheel structure.

[0025] Figure 2 This is a schematic diagram of the basic dimensions of a rolled steel wheel structure.

[0026] Figure 3 This is a comparative schematic diagram of the rolled steel wheel structure and the HESA wheel profile of this application.

[0027] Figure 4 The image shows the Mises stress cloud diagram of the rolled steel wheel structure in this application.

[0028] Figure 5 This is a schematic diagram showing the verification results of the fatigue strength of the rolled steel wheel structure in this application.

[0029] Figure 6 This is a schematic diagram comparing the circumferential stress of the rolled steel wheel structure and the HESA wheel tread in this application.

[0030] Figure 7 This is a schematic diagram comparing the Mises stress on the tread of the HESA wheel tread of the rolled steel wheel structure of this application.

[0031] Figure 8 This is a schematic diagram showing the calculation results of the static strength of the wheel-rail contact in the rolled steel wheel structure of this application.

[0032] Figure 9 This is a schematic diagram showing the calculation results of the wheel-rail contact fatigue strength of the rolled steel wheel structure in this application. Detailed Implementation

[0033] The following is a detailed description of a rolled steel wheel structure for trucks with a diameter of 840mm provided by this utility model, with reference to the accompanying drawings and specific embodiments.

[0034] Figure 1-2As shown, a steel wheel structure for a freight car with a diameter of 840mm includes a hub 1, spokes 2 and rim 3. The wheel diameter is 840mm, the rim 3 thickness is 60mm, the inner diameter of the rim 3 is 720mm, the hub 1 bore diameter is 210mm, and the overall weight is 314kg. The overall structure has an S-shaped spoke design and an LM-shaped rim tread shape.

[0035] The spoke 2 has an S-shaped structure and a thickness of 20 mm.

[0036] The outer diameter of hub 1 is 286mm, the thickness of hub 1 is 38mm, and the width of hub 1 is 178mm.

[0037] The rim width is 135mm, and the inner rim distance is 68mm.

[0038] The main body of the spoke 2 is composed of two concentric circular arcs.

[0039] The angle range of the transition line from the rim 3 to the inner and outer spokes 2 is 1° to 20°. If the transition line segment is short, it can be fitted with a circular arc.

[0040] Preferably, the angles a and b of the transition line from the rim to the inner and outer spokes are 13° and 4°, respectively.

[0041] Preferably, the angles a and b of the transition line from the rim to the inner and outer spokes are 9° and 6°, respectively.

[0042] The angle range of the straight line transitioning from the hub to the inner and outer spokes is 1° to 20°. If the transition line segment is short, it can be fitted with a circular arc.

[0043] Preferably, the angles c and d of the transition line from the hub to the inner and outer spokes are 9° and 9°, respectively.

[0044] Preferably, the angles c and d of the transition line from the hub to the inner and outer spokes are 9° and 8°, respectively.

[0045] The existing 70t-class freight car integral rolled steel wheels are secondary wear wheels with a rim thickness of 50mm. They employ tread braking and an S-shaped spoke structure, with an overall weight of approximately 315kg and a commercial operating speed of 120km / h. Since their successful development in 2001, these wheels have played a positive role in the rapid development of railway freight due to their stable service reliability. However, with the increasing axle load, higher operating speeds, and harsher braking conditions, rim cracking has gradually become apparent and is showing an increasing trend.

[0046] The main reason for this is the limited design capabilities and understanding of operating conditions at the time, resulting in a small safety margin in the initial design. Furthermore, the increasing speed of freight cars, the increasing load on individual vehicles, and the gradually increasing traction tonnage of trains in recent years have further highlighted this problem.

[0047] Studies of the fault characteristics revealed that wheels exhibiting rim cracking had rims with insufficient thickness, approaching the minimum rim thickness limit. To reduce the probability of rim cracking, the operating departments increased the upper limit of rim thickness during factory repairs and train inspections. These measures, to some extent, shortened the wheel's service life. Relevant statistics indicate that railway freight car wheel maintenance costs account for approximately 12%–25% of overall car maintenance costs and 25%–40% of bogie maintenance costs. Reduced wheel lifespan significantly increases freight car maintenance costs.

[0048] To address this issue, this utility model patent determines the interface dimensions such as rim thickness and rim inner diameter of the new truck wheel based on design requirements. It also optimizes the spoke structure using parametric modeling, finite element optimization design, and multi-objective optimization techniques, resulting in a new truck wheel design with a rolling circle diameter of φ840. This design increases the rim thickness to 60mm and maintains the same interface dimensions as the HESA wheel.

[0049] Compared to the HESA wheel structure, this invention features a lighter weight and higher fatigue strength. Overall performance indicators, including wheel-rail contact strength and thermal resistance, are further improved compared to the HESA wheel. In terms of interchangeability, this invention is interchangeable with HESA wheels, achieving the development goals of "lightweighting" and "high reliability and safety in service" in wheel design, and promoting the overall technological advancement of railway freight car running gear.

[0050] Regarding structural strength, the structural strength of this utility model was verified using TB / T 3463-2016 "Method for Evaluating the Strength of Railway Vehicle Wheels". The Mises stress cloud diagram of this utility model is shown below. Figure 4 The static strength verification results and comparison with HESA wheels are shown in Table 1. The minimum safety factor for static strength is 1.44. The fatigue strength verification results are shown in... Figure 5 The fatigue strength verification results and comparison with HESA wheels are shown in Table 2. The minimum safety factor for fatigue strength is 1.32. The strength performance indicators of this utility model meet the relevant provisions of TB / T3506-2018 and have a high strength margin.

[0051] Table 1. Comparison of static strength between this utility model and HESA wheels (axle load 25t)

[0052]

[0053]

[0054] Table 2 Comparison of fatigue strength between this utility model and HESA wheels (axle load 25t)

[0055]

[0056] Regarding wheel weight reduction, the existing HESA wheel has a rim thickness of 50mm and a weight of 315kg; the rim thickness of this utility model is 60mm and the weight is 314kg. Under the premise of keeping the hub thickness unchanged and increasing the rim thickness by 10mm, it is still 1kg lighter than the HESA wheel, and the safety margins for static strength and fatigue strength are both greater than those of the HESA wheel.

[0057] Regarding braking thermal resistance, truck wheels employ tread braking, where the tread endures severe braking thermal loads during braking. The shallow surface layer of the tread experiences very high stress in a short period, leading to stress concentration and plastic deformation. After the wheel cools, residual tensile stress may appear on the tread surface, making it prone to developing braking thermal cracks after repeated braking. This invention optimizes the wheel spoke structure, reducing tread stress during braking and thus improving the wheel's thermal resistance.

[0058] During parking braking, the simulation results of the tread circumferential stress and tread Mises stress of this utility model and the HESA wheel in the new manufacturing state, semi-wear state and wear-to-limit state are shown in the figure. Figure 6 and Figure 7 Simulation results show that, under new, semi-worn, and worn-to-limit conditions, the Mises stress on the tread of the present invention is 8 MPa, 17 MPa, and 33 MPa lower than that of the HESA wheel, respectively, and the circumferential compressive stress on the tread is 10 MPa, 22 MPa, and 43 MPa lower, respectively. This indicates that, under the same wear conditions, the Mises stress and circumferential stress on the tread of the present invention are both lower than those of the HESA wheel, and the difference becomes more significant as the rim becomes thinner, demonstrating that the present invention has stronger heat resistance.

[0059] Regarding wheel-rail contact performance, simulation results of the static strength and fatigue performance of the wheel-rail contact under a 25t axle load are shown below. Figure 8 and Figure 9 The comparison of the wheel-rail contact strength between this utility model and the HESA wheel is shown in Tables 3 and 4.

[0060] Table 3 Simulation results of wheel-rail contact strength of this utility model and HESA wheel

[0061]

[0062] The main differences in the static contact strength between this utility model and the HESA wheel are as follows:

[0063] (1) Under typical rim thickness conditions such as new manufacturing state, semi-worn state, and worn-to-limit state, the mises stress corresponding to this utility model is less than that of the HESA wheel. The difference is not obvious in the new manufacturing state, but the difference becomes more significant as the rim becomes thinner.

[0064] (2) The maximum stress location of this utility model is located inside the rim. However, as the rim becomes thinner, the maximum stress location of the wheel tends to move closer to the tread. This indicates that as the rim becomes thinner, the stress concentration area of ​​the wheel gradually shifts towards the shallow surface of the tread. The maximum stress location of the HESA wheel is located in the shallow surface of the tread.

[0065] (4) In the new and semi-worn states, the wheel-rail contact stress of this utility model is less than that of the HESA wheel; in the worn-to-limit state, the wheel-rail contact stress of this utility model is comparable to that of the HESA wheel.

[0066] The fatigue life simulation estimation results under a 25t axle load are shown in Table 4.

[0067] Table 4 Simulation results of wheel contact fatigue life of this utility model and HESA.

[0068]

[0069] The calculation results shown in Table 4 will certainly differ from the actual situation, but they can predict the wheel-rail contact life in terms of trends. Based on Table 4, the main differences between the wheel-rail contact fatigue performance of this utility model and the HESA wheel are as follows:

[0070] (1) Under typical rim thickness conditions such as new manufacturing state, semi-worn state, and worn-to-limit state, the contact fatigue life corresponding to this utility model is greater than that of HESA wheel. The difference is not obvious in the new manufacturing state, but the difference becomes more significant as the rim becomes thinner.

[0071] (2) In the new state and the semi-worn state, the rail contact fatigue life of this utility model is slightly longer than that of the HESA wheel, and in the worn-to-limit state, it is slightly shorter than that of the HESA wheel.

[0072] Example 1

[0073] During performance testing, static strength tests showed a maximum stress of 256.3 MPa under the wear-to-limit condition, with a safety factor of 1.44, significantly better than the 311.1 MPa of the HESA wheel. Fatigue tests, under mechanical load conditions, showed a cyclic stress of 238 MPa, with a safety factor of 1.32, also better than the comparative sample. Thermal resistance tests confirmed a 10-43 MPa reduction in tread circumferential stress, significantly improving resistance to thermal cracking. Wheel-rail contact test data showed contact stress controlled within the ideal range of 1111-1164 MPa, with the contact area maintained at 95.86-91.92 mm². 2 The contact fatigue life is superior to that of existing technologies, and these test results fully verify the technical advantages of the present invention. Figure 4By comparing the contour differences between the wheel of this invention and the HESA wheel, the specific improvements of increased rim thickness and optimized spoke shape are visually demonstrated, providing a visual explanation for performance enhancement.

[0074] Example 2

[0075] In practical applications, tests were conducted on a 70t general-purpose truck with an axle load of 25t and an operating speed of 120km / h. Data from 100,000 kilometers of cumulative operation showed that the flange wear was 0.5mm / 10,000km and the tread wear was 0.3mm / 10,000km. In terms of economic benefits, the service life was extended by approximately 25%, the maintenance cycle was extended by 30%, and maintenance costs were reduced by 15-20%. These actual operating data confirm the superior performance of this invention in engineering applications. The stress cloud diagram visually displays the stress distribution of the wheel under various working conditions, verifying the rationality of the structural design and providing a theoretical basis for long-term reliability.

[0076] Finally, it should be noted that the above embodiments are only used to describe the technical solutions of the present invention and not to limit the technical methods. The present invention can be extended to other modifications, variations, applications and embodiments, and therefore all such modifications, variations, applications and embodiments are considered to be within the scope of the present invention.

Claims

1. A rolled steel wheel structure for a freight car with a diameter of 840 mm, comprising a hub (1), spokes (2), and a rim (3), characterized in that, The wheel has a diameter of 840mm, a rim (3) thickness of 60mm, an inner diameter of 720mm, a hub (1) bore diameter of 210mm, and an overall weight of 314kg. The overall structure features an S-shaped spoke design and an LM-shaped rim tread shape.

2. The rolled steel wheel structure for trucks with a diameter of 840mm according to claim 1, characterized in that, The spokes (2) have an S-shaped structure and a thickness of 20 mm.

3. The 840mm diameter rolled steel wheel structure for trucks according to claim 1, characterized in that, The outer diameter of the hub (1) is 286mm, the thickness of the hub (1) is 38mm, and the width of the hub (1) is 178mm.

4. The rolled steel wheel structure for trucks with a diameter of 840mm according to claim 1, characterized in that, The rim (3) is 135mm wide and the inner rim distance is 68mm.

5. The rolled steel wheel structure for trucks with a diameter of 840mm according to claim 1, characterized in that, The main body of the spokes (2) is composed of two concentric circular arcs.

6. The 840mm diameter rolled steel wheel structure for trucks according to claim 1, characterized in that, The angle range of the transition line from the rim (3) to the inner and outer spokes (2) is 1° to 20°. If the transition line segment is short, it can be fitted with a circular arc.

7. The rolled steel wheel structure for trucks with a diameter of 840mm according to claim 6, characterized in that, The angles (a) and (b) of the transition line from the rim (3) to the inner and outer spokes (2) are 13° and 4°, respectively.

8. The rolled steel wheel structure for trucks with a diameter of 840mm according to claim 6, characterized in that, The angles (a) and (b) of the transition line from the rim (3) to the inner and outer spokes (2) are 9° and 6°, respectively.

9. The rolled steel wheel structure for trucks with a diameter of 840mm according to claim 1, characterized in that, The angle range of the transition line from the hub (1) to the inner and outer spokes (2) is 1° to 20°. If the transition line segment is short, it can be fitted with a circular arc.

10. The rolled steel wheel structure for trucks with a diameter of 840mm according to claim 9, characterized in that, The angles (c) and (d) of the transition line from the hub (1) to the inner and outer spokes (2) are 9° and 9°, respectively.

11. The 840mm diameter rolled steel wheel structure for trucks according to claim 9, characterized in that, The angles (c) and (d) of the transition line from the hub (1) to the inner and outer spokes (2) are 9° and 8°, respectively.

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