Assembly clearance control method for lining structure in thrust wheel of ultra-large excavator
By using stepped heating tests and nonlinear model reverse design, the thermal expansion problem of the track roller of an ultra-large excavator under temperature changes was solved, thus achieving the reliability and safety of the track roller and simplifying the design process.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHAANXI ARD MASCH CO LTD
- Filing Date
- 2025-12-19
- Publication Date
- 2026-04-21
AI Technical Summary
Traditional assembly methods fail to effectively consider the thermal expansion behavior of the track rollers of ultra-large excavators under temperature changes, resulting in deviations between the design clearance and the actual working clearance. This may cause the bushings to seize up with the axle, wear out or detach, affecting the safety of the entire machine.
Data was obtained through stepped heating tests, a nonlinear model was established, and the assembly dimensions at room temperature were designed in reverse to ensure that the working clearance between the bushing and the shaft is reasonable throughout the temperature range. A combination of interference fit and clearance fit was adopted, and nonlinear curve fitting was used to back-calculate the target machining dimensions and assembly parameters of each component.
It effectively avoids high-temperature seizure or impact wear, ensures the reliability and interference fit between the bushing and the wheel body, prevents separation, simplifies design parameter management, and is suitable for track roller products of different models and materials.
Smart Images
Figure CN121894065A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of large-scale engineering machinery technology, specifically a method for controlling the assembly clearance of the bushing structure in the support roller of an ultra-large excavator. Background Technology
[0002] The track rollers of ultra-large excavators are key load-bearing components of the chassis traveling mechanism, and their reliability directly affects the overall performance of the machine. The track roller components mainly include the wheel body, axle, end cap, bushing (bearing shell), floating seal, etc.
[0003] The traditional assembly method is as follows: the bushing is pressed into the wheel body with an interference fit to form a "wheel body assembly", which then forms a clearance fit with the shaft; during operation, the wheel body assembly rotates relative to the wheel shaft.
[0004] Currently, the design of ultra-large excavator support rollers mainly relies on preliminary theoretical calculations and empirical data from bimetallic bearings. However, with the application of new materials such as all-copper bearings, the thermal expansion behavior of the bushings, wheel body, and shafts differs significantly from that of traditional bimetallic materials when operating from room temperature to high temperatures (above 120°C). Failure to fully consider the actual expansion patterns under continuous temperature changes will lead to significant deviations between the designed clearance and the actual working clearance. Insufficient clearance can easily cause the bushings and axles to seize at high temperatures, resulting in abnormal wear or jamming; excessive clearance leads to increased impact loads, lubrication failure, and premature wear. In severe cases, improper interference fit design may even cause relative separation between the wheel body and bushing at high temperatures, affecting the safety of the entire machine. Summary of the Invention
[0005] The purpose of this invention is to provide a method for controlling the assembly clearance of the bushing structure in the support roller of an ultra-large excavator, so as to solve the problems mentioned in the background art.
[0006] To achieve the above objectives, the present invention provides the following technical solution:
[0007] A method for controlling the assembly clearance of the bushing structure in the support roller of an ultra-large excavator includes the following steps:
[0008] S1. Test component preparation: The bushing is pressed into the support wheel body using an interference fit to form the wheel body assembly; then the wheel axle is installed into the bushing using a clearance fit.
[0009] S2. Room temperature reference measurement: At room temperature, measure the inner diameter of the support wheel body, the outer and inner diameters of the bushing, the inner diameter of the wheel assembly, and the outer diameter of the wheel axle;
[0010] S3. Stepped heating and real-time measurement: Place each component in the test furnace and gradually increase the temperature to the maximum operating temperature from the initial temperature with a predetermined gradient; after holding at each target temperature for a predetermined time, measure the dimensional data of the corresponding parts of each component at that temperature.
[0011] S4. Establishment of temperature and size function model: Based on the temperature and size data obtained in step S3, nonlinear curve fitting is performed on the inner hole of the support roller, the outer and inner diameters of the bushing, the inner hole of the wheel assembly and the outer diameter of the wheel axle to obtain the continuous prediction function of the corresponding part of each component with respect to temperature.
[0012] S5. Determining Assembly Dimensions at Room Temperature: Based on the temperature-dimension correlation prediction function established in step S4, and with the ideal fit condition at the highest operating temperature as a constraint, the target machining dimensions and assembly parameters of each component at room temperature are calculated in reverse.
[0013] S6. Bushing Machining and Track Roller Assembly: Based on the target value of the bushing inner diameter and the range of assembly interference obtained in step S5, guide the bushing machining and track roller assembly.
[0014] As a further aspect of the present invention: in step S3, the initial temperature is 50°C, the maximum operating temperature is 120°C, and the temperature gradient is 10°C; the holding time at each temperature point is 1 hour.
[0015] As a further aspect of the present invention: in step S4, a quadratic or cubic polynomial is used to perform nonlinear curve fitting on the corresponding parts of each component; the formula for the prediction function of the corresponding parts of each component is:
[0016] y = k1*x 2 +k2*x 2 +k3*x+C, where x is the temperature, y is the predicted value of the corresponding part of the component, k1, k2, k3 are fitting coefficients, and C is a constant term.
[0017] As a further aspect of the present invention: in step S5, the specific steps for determining the assembly dimensions at room temperature are as follows:
[0018] S51. Determine the maximum operating temperature T based on the operating conditions. max The target working clearance G between the inner diameter of the lower bushing and the outer diameter of the wheel axle target ; and the minimum residual interference δ between the outer diameter of the bushing and the inner bore of the support roller. min ;
[0019] S52. Using the bushing inner diameter prediction function and the wheel axle outer diameter prediction function, combined with the target working clearance G target The design target size of the bushing inner diameter at room temperature is obtained by reverse calculation.
[0020] S53. Using the bushing outer diameter prediction function and the support roller inner hole prediction function, combined with the minimum residual interference δ min The design target size for the interference fit between the bushing and the support roller body at room temperature was obtained by reverse calculation.
[0021] As a further aspect of the present invention: in step S51, the target working gap G target The equation satisfies the following bar structure: in, and The inner diameter of the bushing and the outer diameter of the wheel axle are respectively at the highest operating temperature T. max The prediction function under G; target For the bushing inner diameter and the wheel axle outer diameter at the highest operating temperature T max The target working interval;
[0022] Minimum residual interference δ min The equation satisfies the following bar structure: in and The outer diameter of the bushing and the inner bore of the support roller are respectively at the highest operating temperature T. max The prediction function under δ; min For the bushing outer diameter and the support roller inner bore at the highest operating temperature T max The minimum residual interference.
[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0024] This invention obtains data through actual step heating experiments and uses a nonlinear model for fitting, which fully reflects the nonlinear characteristics of thermal expansion of metallic materials. The fitting error is small and significantly better than traditional linear theoretical calculations or simple empirical estimations.
[0025] Based on the measured expansion law, the room temperature assembly dimensions were designed in reverse to ensure that the working clearance between the bushing and the shaft is always within a reasonable range from room temperature to the maximum working temperature. This effectively avoids high temperature seizure or impact wear, while ensuring the reliability of the interference fit between the bushing and the wheel body and preventing separation.
[0026] This method establishes a standardized testing and calculation process, which is applicable to the development of support rollers of different models and materials; the expansion prediction of each component can be managed through a unified function model, simplifying the management and use of design parameters. Attached Figure Description
[0027] Figure 1 A flowchart illustrating a method for controlling the assembly clearance of the bushing structure in the support roller of an ultra-large excavator;
[0028] Figure 2 This is a schematic diagram of the structure of the support roller of an ultra-large excavator;
[0029] Figure 3 A schematic diagram showing the measurement position of the support roller body in a super-large excavator support roller;
[0030] Figure 4 This is a schematic diagram showing the measurement position of the wheel assembly in the support roller of an ultra-large excavator.
[0031] Figure 5 This is a schematic diagram showing the measurement position of the bushing in the support roller of an ultra-large excavator.
[0032] Figure 6 This is a schematic diagram showing the measurement position of the axle of the support roller of an ultra-large excavator.
[0033] In the diagram: 1. Support roller body; 2. Bushing; 3. Axle. Detailed Implementation
[0034] Please see Figure 1 In this embodiment of the invention, a method for controlling the assembly clearance of the bushing structure in the support roller of an ultra-large excavator includes the following steps:
[0035] S1. Test component preparation: The bushing 2 is pressed into the support wheel body 1 using an interference fit to form the wheel assembly; then the wheel axle 3 is installed into the bushing 2 using a clearance fit; (e.g., ...) Figure 2 As shown;
[0036] S2. Room temperature reference measurement: At room temperature, measure the inner diameter of the support wheel body 1, the outer and inner diameters of the bushing 2, the inner diameter of the wheel assembly, and the outer diameter of the wheel axle 3.
[0037] S3. Stepped heating and real-time measurement: Place each component in the test furnace and gradually heat it to the maximum operating temperature from the initial temperature with a predetermined gradient; after holding at each target temperature for a predetermined time, measure the dimensional data of the corresponding parts of each component at that temperature; wherein, the initial temperature is 50℃, the maximum operating temperature is 120℃, the temperature gradient is 10℃; the holding time at each temperature is 1 hour.
[0038] S4. Temperature and Dimension Function Model Establishment: Based on the temperature and dimension data obtained in step S3, nonlinear curve fitting is performed on the inner diameter of the support wheel body 1, the outer and inner diameters of the bushing 2, the inner diameter of the wheel assembly, and the outer diameter of the axle 3, respectively, to obtain continuous prediction functions of the dimensions of the corresponding parts of each component with respect to temperature; among them, quadratic or cubic polynomials are used to perform nonlinear curve fitting on the corresponding parts of each component; the formula for the prediction function of the corresponding parts of each component is: y = k1*x 2 +k2*x 2+k3*x+C, where x is the temperature, y is the predicted value of the corresponding part of the component, k1, k2, and k3 are fitting coefficients, and C is a constant term; k1, k2, k3, and C are calculated experimentally.
[0039] For example, taking the track roller body, axle, wheel assembly, and bushing of a 135T super-large excavator as an example, experiments were conducted to measure the actual values and expansion of each component at corresponding locations under different temperatures. The experimental data are as follows:
[0040] (1) The measured values and expansion of the inner bore of the support roller at different temperatures are shown in Tables 1-4 below; the measurement locations are as follows: Figure 3 As shown;
[0041] Table 1. Measured values of the inner bore of the support roller at different locations.
[0042]
[0043]
[0044] Table 2. Expansion of the inner bore of the support roller at different locations.
[0045]
[0046]
[0047] Table 3 Average measured values of the inner bore of the support roller.
[0048]
[0049] Table 4 shows the average expansion of the inner bore of the support roller.
[0050]
[0051] From the experimental results in Tables 1-4 above, we can conclude that:
[0052] The inner diameter of the support wheel body (1) increases with temperature. At 120℃, the inner diameter expansion is 0.113 mm. (2) The measured values and expansion of the inner diameter of the wheel assembly at different temperatures are shown in Tables 5-8 below; the measurement locations are as follows. Figure 4 As shown in Table 5; Measured values of the inner bore of the wheel assembly at different positions.
[0053]
[0054]
[0055] Table 6. Expansion of the inner bore of the wheel assembly at different locations.
[0056]
[0057]
[0058] Table 7 Average measured values of the inner bore of the wheel assembly.
[0059]
[0060] Table 8 shows the average expansion of the inner bore of the support roller.
[0061]
[0062] From the experimental results in Tables 5-8 above, we can conclude that:
[0063] The inner diameter of the wheel assembly increases with temperature. At 120℃, the inner diameter expands by 0.103 mm. (3) The measured values and expansion amounts of the inner diameter of the wheel axle at different temperatures are shown in Tables 9-12 below; the measurement locations are as follows: Figure 5 As shown in Table 9; Measured values of the wheel axle outer diameter at different positions.
[0064]
[0065]
[0066] Table 10 Expansion of the outer diameter of the wheel axle at different locations
[0067]
[0068]
[0069] Table 11 Average measured values of wheel axle outer diameter
[0070]
[0071] Table 12 Average Expansion of Wheel Axle Outer Diameter
[0072]
[0073] The test results in Tables 9-12 show that the wheel axle diameter increases with temperature, and the outer diameter expansion is 0.135 mm at 120℃.
[0074] (4) The measured values of the outer and inner diameters of the bushing at different temperatures and the expansion amount are shown in Tables 13-16 below; the measurement locations are as follows: Figure 6 As shown;
[0075] Table 13 Measured values of bushing outer and inner diameters at different locations
[0076]
[0077] Table 14 Expansion of the outer and inner diameters of the bushing at different locations
[0078]
[0079]
[0080] Table 15 Average measured values of bushing outer and inner diameters
[0081]
[0082] Table 16 Average Expansion of Bushing Outer and Inner Diameters
[0083]
[0084] From the experimental results in Tables 13-16 above, we can conclude that:
[0085] Both the outer and inner diameters of the bushing increase with temperature. At 120℃, the outer diameter expands by 0.19 mm and the inner diameter expands by 0.188 mm.
[0086] Based on the above experimental data, the prediction function y=k1*x 2 +k2*x 2 By fitting the data with +k3*x+C, the prediction functions for each component are obtained as follows:
[0087] Bushing inner diameter prediction function:
[0088] Wheel axle outer diameter prediction function: y sh(c) = -1.292 × 10 -7 x 3 +4.375×10 -5 x 2 -0.003542x+139.993;
[0089] Bushing outer diameter prediction function:
[0090] Prediction function for the inner hole of the support roller body (1): y b(c) =1.518×10 -6 x 2 +0.001732x+153.023;
[0091] Where x is in °C and y is in mm; and It is a constant term that needs to be solved, representing the theoretical size of the component at room temperature.
[0092] S5. Determining Assembly Dimensions at Room Temperature: Based on the temperature-dimensional correlation prediction function established in step S4, and using the ideal fit at the highest operating temperature—that is, a reasonable working clearance between bushing 2 and axle 3, and an effective interference fit between bushing 2 and support wheel 1—as constraints, the target machining dimensions and assembly parameters of each component at room temperature are calculated in reverse. The specific steps are as follows:
[0093] S51. Determine the maximum operating temperature T based on the operating conditions. max The target working clearance G between the inner diameter of the lower bushing 2 and the outer diameter of the wheel axle 3 target ; and the minimum residual interference δ between the outer diameter of bushing 2 and the inner hole of support roller body 1. min Among them, the target working gap G target The equation satisfies the following bar structure: in, and The inner diameter of bushing 2 and the outer diameter of axle 3 are respectively at the highest operating temperature T. max The prediction function under G; target For the inner diameter of bushing 2 and the outer diameter of wheel axle 3 at the highest operating temperature T max The target working interval;
[0094] Minimum residual interference δ min The equation satisfies the following bar structure: in and The outer diameter of bushing 2 and the inner diameter of support roller body 1 are respectively at the highest operating temperature T. max The prediction function under δ; min For the distance between the outer diameter of bushing 2 and the inner hole of support roller body 1 at the highest operating temperature T max The minimum residual interference;
[0095] S52. Using the inner diameter prediction function of bushing 2 and the outer diameter prediction function of wheel axle 3, and combined with the target working clearance G target The design target size of the inner diameter of bushing 2 at room temperature is obtained by reverse calculation.
[0096] S53. Using the outer diameter prediction function of bushing 2 and the inner diameter prediction function of support roller body 1, combined with the minimum residual interference δ min The design target size for the interference fit between bushing 2 and support roller body 1 at room temperature was obtained by reverse calculation.
[0097] Let's take the track roller of a 135T super-large excavator as an example; assuming,
[0098] Target working interval G targetRequirements: To prevent seizing at 120℃ and ensure good lubrication, the theoretical single-sided radius clearance is set to 0.10mm~0.15mm. Therefore, the target working clearance range in the diameter direction is defined as: G min =0.20mm,G max =0.30mm;
[0099] Minimum residual interference δ min Requirements: To ensure a reliable connection between the outer diameter of the bushing (2) and the inner hole of the support roller body (1) at a high temperature of 120℃, without relative rotation or separation, the minimum effective diameter interference that must be maintained at this time is set as: δ min@Tmax =0.05mm; Considering the strength of the bushing (2) material (if using all-copper bearings) and the feasibility of the press-fitting process, the maximum allowable diameter interference at room temperature is set as: δ max@material =0.25mm; then
[0100] (1) The design target size of the inner diameter of bushing 2 at room temperature is calculated as follows:
[0101] Equation for target working clearance at 120℃: It must satisfy 0.20≤G(120)≤0.30;
[0102] Calculate the dimensions of the wheel axle at 120℃: y sh(120) = -1.292 × 10 -7 ×120 3 +4.375×10 -5 ×120 2 -0.003542×120+139.993=140.128mm;
[0103] Then, the expression for the bushing inner diameter at 120℃ is:
[0104] Substitute into the target working gap constraint inequality and solve.
[0105]
[0106] Therefore, the median value of the target machining dimension is taken to ensure optimal fault tolerance:
[0107] Therefore, the target design dimension for the bushing inner diameter at room temperature is 140.075 mm;
[0108] (2) The design target size for the interference fit between bushing 2 and support roller 1 at room temperature is calculated as follows:
[0109] Equation for minimum residual interference at 120℃: It must satisfy δ(120)≥0.05mm;
[0110] Calculate the dimensions of the inner bore of the support roller at 120℃: y b(120) =1.518×10 -6 ×120 2 +0.001732×120+153.023=0.225+153.023=153.248mm;
[0111] Then, the expression for the bushing outer diameter at 120℃ is:
[0112] Solving the minimum residual interference constraint inequality
[0113]
[0114] Then, considering the maximum interference limit at room temperature, determine... Upper limit:
[0115] room temperature interference From δ room ≤δ max-material =0.25, therefore:
[0116] C_(s_out)≤153.023+0.25=153.273;
[0117] Then determine the range of interference fit for room temperature assembly: The design range is [152.945, 153.273] mm;
[0118] The corresponding room temperature diameter interference range is: δ min =152.915-153.023=-0.078mm; This shows a negative value (gap), which is unreasonable;
[0119] This shows that: if only to meet the δ at 120℃ min@Tmax The requirement of 0.05mm is acceptable, and gaps may even exist at room temperature; this is unacceptable in engineering because press fitting requires initial interference to ensure bonding strength.
[0120] Therefore, a crucial minimum interference constraint at room temperature must be added, denoted as δ. min-room =0.10mm; (based on connection strength requirements); then:
[0121] Corrected Final design scope: [153.123, 153.273];
[0122] Therefore, the corresponding design target range for the assembly diameter interference is: δ min =153.123-153.023=
[0123] 0.100mm; δ max =153.273-153.023=0.250mm; that is, the design interference is 0.100mm~0.250mm;
[0124] S6. Bushing Machining and Track Roller Assembly: Based on the design target value of the inner diameter of bushing 2 and the range of assembly interference obtained in step S5, guide the machining of bushing 2 and the assembly of track rollers.
[0125] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.
Claims
1. A method for controlling the assembly clearance of the bushing structure in the support roller of an ultra-large excavator, characterized in that, Includes the following steps: S1. Preparation of test components: The bushing (2) is pressed into the support wheel body (1) by an interference fit to form a wheel body assembly; then the wheel axle (3) is installed into the bushing (2) by a clearance fit. S2. Room temperature reference measurement: At room temperature, measure the inner diameter of the support wheel body (1), the outer and inner diameters of the bushing (2), the inner diameter of the wheel assembly, and the outer diameter of the wheel axle (3); S3. Stepped heating and real-time measurement: Place each component in the test furnace and gradually increase the temperature to the maximum operating temperature from the initial temperature with a predetermined gradient; after holding at each target temperature for a predetermined time, measure the dimensional data of the corresponding parts of each component at that temperature. S4. Temperature and size function model establishment: Based on the temperature and size data obtained in step S3, nonlinear curve fitting is performed on the inner hole of the support wheel body (1), the outer and inner diameters of the bushing (2), the inner hole of the wheel assembly and the outer diameter of the wheel axle (3) to obtain the continuous prediction function of the corresponding part of each component with respect to temperature. S5. Determining Assembly Dimensions at Room Temperature: Based on the temperature-dimension correlation prediction function established in step S4, and taking the ideal fit condition at the highest operating temperature as a constraint, the target machining dimensions and assembly parameters of each component at room temperature are calculated in reverse. S6. Bushing machining and support roller assembly: Based on the target value of the inner diameter of bushing (2) and the range of assembly interference obtained in step S5, guide the machining of bushing (2) and the assembly of support roller.
2. The method for controlling the assembly clearance of the bushing structure in the support roller of an ultra-large excavator according to claim 1, characterized in that, In step S3, the initial temperature is 50°C, the maximum operating temperature is 120°C, and the temperature gradient is 10°C; the holding time at each temperature point is 1 hour.
3. The method for controlling the assembly clearance of the bushing structure in the support roller of an ultra-large excavator according to claim 1, characterized in that, In step S4, a quadratic or cubic polynomial is used to perform nonlinear curve fitting on the corresponding parts of each component; the formula for the prediction function of the corresponding parts of each component is: ,in, For temperature, This is the predicted value for the corresponding dimension of the component. , , These are the fitting coefficients. This is a constant term.
4. The method for controlling the assembly clearance of the bushing structure in the support roller of an ultra-large excavator according to claim 1, characterized in that, In step S5, the specific steps for determining the assembly dimensions at room temperature are as follows: S51. Determine the maximum operating temperature based on the operating conditions. The target working clearance between the inner diameter of the lower bushing (2) and the outer diameter of the wheel axle (3) ; and the minimum residual interference between the outer diameter of the bushing (2) and the inner hole of the support roller body (1). ; S52. Using the bushing (2) inner diameter prediction function and the wheel axle (3) outer diameter prediction function, combined with the target working clearance. The design target size of the inner diameter of the bushing (2) at room temperature is obtained by reverse calculation; S53. Using the outer diameter prediction function of bushing (2) and the inner diameter prediction function of support roller body (1), combined with the minimum residual interference. The design target size of the interference fit between the bushing (2) and the support wheel body (1) at room temperature was obtained by reverse calculation.
5. The method for controlling the assembly clearance of the bushing structure in the support roller of an ultra-large excavator according to claim 1, characterized in that, In step S51, the target working gap The equation satisfies the following bar structure: ,in, and The inner diameter of the bushing (2) and the outer diameter of the axle (3) are respectively at the highest operating temperature. The prediction function is as follows; For the bushing (2) inner diameter and the wheel axle (3) outer diameter at the highest operating temperature The target working interval; Minimum residual interference The equation satisfies the following bar structure: ,in and The outer diameter of the bushing (2) and the inner diameter of the support roller body (1) are respectively at the highest operating temperature. The prediction function is as follows; For the bushing (2) outer diameter and the support roller body (1) inner hole at the highest operating temperature The minimum residual interference.