A testing method for the structural load of a slewing bearing vehicle frame

Abstract

The present invention belongs to the field of construction machinery, and particularly relates to a method for testing the load of a swing bearing frame structure, which includes bolt strain gauges, inclination sensors, pressure sensors, a data acquisition module, and a data analysis system; the specific testing method is as follows: Drive the construction machinery onto a horizontal plane, and embed bolt strain gauges in several fixed bolts between the outer ring of the swing bearing and the upper frame structure; horizontally install an inclination sensor on the outer ring of the swing bearing; install pressure sensors at the inlet and outlet of the swing motor; the bolt strain gauges, inclination sensors, and pressure sensors are respectively connected to the data acquisition module through strain acquisition lines, and the data acquisition module is signal-connected to the data analysis system; Drive the construction machinery with all kinds of testing equipment assembled to the specified testing position, adjust the upper vehicle mechanism to the specified parking posture, and perform data zeroing processing on all the collected data. The present invention reduces the heavy vehicle modeling work and can quickly output the load spectrum required for the analysis of the lower vehicle structure.

Description

Technical Field

[0001] The present invention belongs to the field of construction machinery, and particularly relates to a method for testing the structural load of a slewing bearing frame. Background Art

[0002] The stability and structural strength of the lower structure of construction machinery equipment are important indicators affecting the handling stability, comfort and reliability during the operation of the equipment. At present, the force on the lower structure is mainly analyzed statically by combining the vehicle weight, the theoretical maximum digging force, the tipping force and other extreme working condition positions, mainly by theoretical calculation. Moreover, the existing construction machinery products are becoming more and more large-scale, the vehicle weight is difficult to accurately measure, and there are more and more complex and changeable working conditions, the calculation will become more and more complicated. After the calculation result is output, there is still a gap with the actual application working conditions, and the scattered data cannot be used for the life analysis of the lower structure. Summary of the Invention

[0003] In order to overcome the above deficiencies of the prior art, the present invention provides a method for testing the structural load of a slewing bearing frame. The testing method utilizes sensor technology and computational analysis software, and can accurately achieve dynamic load acquisition, providing a new method and new idea for the force analysis of the lower structure of construction machinery.

[0004] The present invention is realized by the following technical solutions: A method for testing the structural load of a slewing bearing frame includes bolt strain gauges, inclination sensors, pressure sensors, a data acquisition module and a data analysis system; the specific testing method is as follows:

[0005] I. Drive the construction machinery to a horizontal plane, embed bolt strain gauges in several fixing bolts between the outer ring of the slewing bearing and the upper frame structure; horizontally install inclination sensors on the outer ring of the slewing bearing; install pressure sensors at the inlet and outlet of the slewing motor; the bolt strain gauges, inclination sensors and pressure sensors are respectively connected to the data acquisition module through strain acquisition lines, and the data acquisition module is signal-connected to the data analysis system;

[0006] II. Drive the construction machinery equipped with various testing equipment in step I to the specified testing position, then adjust the upper mechanism to the specified parking posture, that is, the reference position, and perform data zeroing processing on all the collected data;

[0007] III. The construction machinery performs various typical operations respectively, and during each typical operation, the data collected by the bolt strain gauges, inclination sensors and pressure sensors are transmitted to the data acquisition module;

[0008] IV. The data analysis system acquires the data collected by the data acquisition module, performs instantaneous force analysis on the fixing bolts, extracts the axial tensile and compressive forces of the fixing bolts, calculates the radial shear forces of the fixing bolts through trigonometric functions based on the inclination angle of the slewing bearing, and calculates the rotational shear forces received by the fixing bolts based on the rotational torque of the slewing bearing.

[0009] In some embodiments, in step one, the bolt strain gauges are embedded at the central axis position of the fixing bolts.

[0010] In some embodiments, in step one, the inclination sensor is a high-precision three-axis inclination sensor.

[0011] In some embodiments, in step one, the fixing bolts with the greatest force on the outer ring of the slewing bearing and the fixing bolts that are centrally symmetric to the fixing bolt with the greatest force are selected as a group of corresponding bolts, and the force conditions of this group of corresponding bolts are measured.

[0012] In some embodiments, the tangent line of the circle where the fixing bolts are located on the outer ring of the slewing bearing, and this tangent line is also perpendicular to the line connecting the center of gravity of the upper vehicle and the force application point of the bucket load. The fixing bolt at position A, which is the closest to the tangent point of this tangent line, is the fixing bolt with the greatest force on the outer ring of the slewing bearing.

[0013] The beneficial effects of the present invention are as follows: The technology of the present invention utilizes mechanical calculations and sensing technologies. The axial tensile and compressive forces received by the fixing bolts on the outer ring of the slewing bearing are obtained by using bolt strain gauges. The axial tensile and compressive forces received by the fixing bolts on the inner ring of the slewing bearing are calculated from the axial tensile and compressive forces received by the fixing bolts on the outer ring of the slewing bearing. The axial shear forces of the fixing bolts on the inner ring of the slewing bearing are obtained through trigonometric calculations, and the rotational shear forces received by the fixing bolts on the inner ring of the slewing bearing are inversely calculated in combination with the rotational torque to obtain the instantaneous forces of the fixing bolts. The load spectrum is output through the computer data analysis system. It reduces the heavy vehicle modeling work, can quickly output the load spectrum required for the structural analysis of the lower vehicle, and is convenient for subsequent mechanical analysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 Schematic diagram of the installation and testing equipment of each sensor of the present invention;

[0015] Figure 2 Schematic diagram of the slewing bearing structure;

[0016] Figure 3 Schematic diagram of the instantaneous force of the fixing bolts of the present invention;

[0017] Figure 4 Schematic diagram of the crawler excavator adjusted to the reference position;

[0018] Figure 5Schematic diagram of the maximum forward tipping force of a crawler excavator;

[0019] Figure 6 Analysis diagram of the equivalent force on the outer ring of the slewing bearing

[0020] Figure 7 Analysis diagram of the force transmission between the inner and outer rings of the slewing bearing;

[0021] Figure 8 Analysis diagram of the static slewing moment;

[0022] In the figure, 1. Bolt strain gauge, 2. Fixed bolt, 3. Slewing bearing, 4. Lower frame, 5. Inclination sensor, 6. Pressure sensor, 7. Data acquisition module, 8. Data analysis system. Specific implementation mode

[0023] The present invention will be further described below with reference to the drawings and embodiments.

[0024] In this embodiment, taking the maximum forward tipping force of the crawler excavator as the analysis object, when the boom is parallel to the crawler, one-third of the crawler length leaves the ground. As Figure 5 shown, part of the crawler on the ground provides support for the whole machine. The tipping force Ft and the weight G of the whole machine achieve moment balance. However, since the center of gravity position of the whole machine is not necessarily on the center line, S 1 and S 2 are actually approximate values, that is:

[0025] G * S 1 ≈ F t * S 2 (1)

[0026] Therefore, the traditional method of obtaining the lower vehicle load spectrum by calculating the forces of the excavator is not very accurate. And to analyze the lower frame, it is very complicated to complete the establishment of the entire upper vehicle model. In order to obtain the lower vehicle load input more accurately and directly, the force on the slewing bearing is directly analyzed. As Figure 6 and Figure 7 shown, the outer ring of the slewing bearing is a rigid ring structure. When subjected to external forces, the forces on the fixed bolts show a geometric circular increasing or decreasing trend. When obtaining the force conditions of a group of corresponding position bolts, the force conditions of the entire outer ring of the slewing bearing can be understood. Due to the existence of the center of gravity G of the upper vehicle 0Regarding the issue that it is not necessarily on the center line, representative position bolts need to be selected for force analysis. The method for determining the representative position bolts is as follows: The tangent line of the circle where the fixing bolts on the outer ring of the slewing bearing are located, and this tangent line is also perpendicular to the line connecting the center of gravity of the upper carriage and the force application point of the bucket load. Select the fixing bolt at position A, which is the closest to the tangent point of this tangent line. Additionally, select the fixing bolt at position B, which is the centrosymmetric position of position A, to form a set of bolts at corresponding positions. By measuring the force conditions of this set of corresponding bolts, the force conditions of the bolts at other positions can be mapped and calculated. Of course, in order to calculate the force conditions of the bolts at other positions more accurately, another set of bolts can be found for measurement to assist in verification.

[0027] By analyzing the structure of the slewing bearing, it can be known that the inner ring and the outer ring of the slewing bearing are in rigid contact axially. The force received by the outer ring of the slewing bearing will be synchronously transmitted to the inner ring of the slewing bearing. However, due to the different installation radii of the fixing bolts of the inner and outer rings, torque conversion is required. At the same time, there is a relative rotational movement between the inner and outer rings of the slewing bearing, and the force application position of the inner ring will change with the rotation of the upper carriage structure. However, the maximum force application position of the inner ring of the slewing bearing always corresponds to the maximum force application position of the outer ring of the slewing bearing, as Figure 7 shown in the force analysis.

[0028] Based on the above discussion, the specific test method is as follows: As Figures 1 to 3 shown, the outer ring of the slewing bearing 3 is fixed to the upper carriage through fixing bolts, and the inner ring of the slewing bearing 3 is fixed to the lower carriage 4 through fixing bolts. Obtain the representative position bolts on the outer ring of the slewing bearing 3. Drive the construction machinery to a horizontal plane, replace the bolts at the representative positions with fixing bolts 2 with bolt strain gauges 1, and horizontally install an inclination sensor 5 on the outer ring of the slewing bearing 3; install pressure sensors 6 at the inlet and outlet of the slewing motor; as Figure 1 shown, lead out the acquisition lines, and connect the bolt strain gauge 1, the inclination sensor 5, and the pressure sensor 6 to the data acquisition module 7 together. The data acquisition module 7 is signal-connected to the data analysis system 8.

[0029] Drive the construction machinery with all types of test equipment assembled to the specified test position. The crawler excavator is in a horizontal position. As Figure 4 shown, adjust the upper carriage mechanism to the specified parking posture, that is, the tooling device cylinder on the telescopic boom of the crawler excavator is in the fully extended position, as the reference position, perform zeroing of the test signal, and start recording the signal data.

[0030] The construction machinery performs various typical operations respectively. During each typical operation, the data collected by the bolt strain gauge 1, the inclination sensor 5, and the pressure sensor 6 are transmitted to the data acquisition module 7. Specifically, adjust the crawler excavator in the reference position to the forward tipping force position, as Figure 5As shown, according to the tipping force test method, the maximum tipping force is tested, and at the same time, the stress value of the bolt strain gauge 1 in the fixing bolt 2 of the slewing bearing at this position, as well as the inclination data of the inclination sensor 5 and other values are recorded. According to the principle of theoretical mechanics, at the static tipping force limit position, the fixing bolt 2 on the outer ring of the slewing bearing 3 is mainly subjected to the axial tensile and compressive force f a and the radial shear force f b . The axial tensile and compressive force f a is directly obtained through testing. According to trigonometric functions, the radial shear force f b can be calculated as follows:

[0031]

[0032] In the formula: α--is the tipping angle of the slewing bearing.

[0033] Further analyzing the force transmission of the inner and outer rings of the slewing bearing, relative to the rotation center, the forces on the fixing bolts of the inner ring of the slewing bearing corresponding to the maximum force position of the outer ring are as follows:

[0034]

[0035] In the formula: R 内 --is the installation radius of the fixing bolt on the inner ring of the slewing bearing, mm;

[0036] R 外 --is the installation radius of the fixing bolt on the outer ring of the slewing bearing, mm.

[0037] Given the maximum axial tensile force value of the fixing bolt on the inner ring of the slewing bearing and the axial tensile force value of the corresponding bolt, and the fixing bolts connecting the inner ring of the slewing bearing to the lower frame are evenly distributed in a circle, so the forces on adjacent bolts show a regular distribution. Since the slewing bearing is a centrosymmetric structure, only the force conditions of half of the bolts need to be obtained, and the other half is symmetric to it.

[0038] Adding several evenly distributed bolt strain gauge fixing bolts within half of the circumferential range of the outer ring of the slewing bearing can draw the force distribution curve. According to the tipping angle of the slewing bearing, the radial shear force f' b of the fixing bolt on the inner ring of the slewing bearing can be synchronously measured using formula (2) and formula (3). Through several data analyses, the force law of the evenly distributed fixing bolts of the slewing bearing can be obtained. That is, after obtaining the maximum axial tensile force of the fixing bolt and the axial tensile force of the corresponding bolt, the axial tensile force of the fixing bolt at any position on the inner ring of the slewing bearing can be calculated according to the number and distribution of the bolts.

[0039] The above is mainly used for the bolt force analysis under the limit working conditions in the case of static non-rotation operation. If the upper vehicle rotates, the fixing bolts of the slewing bearing also need to increase the rotational shear force to overcome the rotational torque of the upper vehicle, such as Figure 8As shown in the figure, the maximum turning force F is obtained through the turning moment test method 0 , and thus the turning force T received by the fixing bolts of the inner ring of the slewing bearing is calculated

[0040] T = F 0 *L (4)

[0041] Where: L--is the horizontal distance from the center of the slewing bearing to the center of gravity of the bucket

[0042] When conducting the dynamic slewing bearing load test, it is necessary to obtain the dynamic slewing moment generated by overcoming the inertial moment of the working device. The greater the load, the greater the slewing inertial moment, which cannot be obtained through the slewing moment test method. This test method measures the pressure difference between the inlet and outlet of the slewing hydraulic motor and converts the instantaneous slewing moment M borne by the slewing bearing

[0043]

[0044] Where: n 0 --is the number of slewing motors

[0045] Δp--is the pressure difference between the inlet and outlet of the slewing motor, Mpa

[0046] η--is the output efficiency of the slewing motor

[0047] η j --is the transmission efficiency of the slewing motor reducer and the slewing bearing

[0048] i--is the transmission ratio of the slewing reducer

[0049] i 0 --is the transmission ratio of the slewing reducer and the slewing bearing

[0050] Since the fixing bolts of the inner ring of the slewing bearing are evenly distributed, the rotational shear force received by each bolt is

[0051]

[0052] Where: n--is the number of fixing bolts on the inner ring of the slewing bearing

[0053] Complete the actual load acquisition under typical working conditions, and output the standard load spectrum of the inner ring of the slewing bearing through the data analysis system 8 for application in simulation analysis

[0054] In summary, the present invention uses simple physical principles and sensing test technologies to provide a convenient method for testing and converting the loads of the slewing bearing frame structure. This method can save the heavy design work and finite element model conversion work required for modeling, directly obtain the mechanical analysis load input of the lower frame, and is simple and easy to implement, saving manpower

[0055] In some embodiments, in step one, the bolt strain gauge 1 is embedded at the central axis position of the fixing bolt 2, without damaging the surface structure and structural strength of the fixing bolt. After the test, the strain acquisition wire can be directly cut off without reinstalling the fixing bolt.

[0056] In some embodiments, in step one, the inclination sensor 5 is a high-precision three-axis inclination sensor, which can truly reflect the combined inclination of the slewing bearing relative to the X-axis, Y-axis, and Z-axis.

[0057] In some embodiments, in step one, the fixing bolt 2 with the greatest force on the outer ring of the slewing bearing 3 and the fixing bolt 2 in the centrosymmetric position with respect to the fixing bolt 2 with the greatest force are selected as a group of corresponding bolts, and the force conditions of this group of corresponding bolts are measured.

[0058] The above description is only a preferred embodiment of the present invention, and does not impose any form of limitation on the present invention. Any simple modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention are all within the scope of the technical solution of the present invention.

Claims

1. A method for testing the load of a swing bearing frame structure, characterized in that: it includes a bolt strain gauge (1), an inclination sensor (5), a pressure sensor (6), a data acquisition module (7) and a data analysis system (8); the specific test method is as follows: I. Drive the construction machinery to a horizontal plane, embed bolt strain gauges (1) in several fixing bolts (2) between the outer ring of the slewing bearing (3) and the upper frame structure; horizontally install an inclination sensor (5) on the outer ring of the slewing bearing (3); install pressure sensors (6) at the inlet and outlet of the slewing motor; the bolt strain gauges (1), the inclination sensor (5) and the pressure sensor (6) are respectively connected to the data acquisition module (7) through strain acquisition lines, and the data acquisition module (7) is signal-connected to the data analysis system (8); II. Drive the construction machinery with all kinds of test equipment assembled in step I to the specified test position, then adjust the upper mechanism to the specified parking posture, that is, the reference position, and perform data zeroing processing on all the collected data; III. The construction machinery performs various typical operations, and during each typical operation, the data collected by the bolt strain gauge (1), the inclination sensor (5) and the pressure sensor (6) are transmitted to the data acquisition module (7); IV. The data analysis system (8) obtains the data collected by the data acquisition module (7), performs instantaneous force analysis on the fixing bolts (2), extracts the axial tensile and compressive forces of the fixing bolts (2), calculates the radial shear force of the fixing bolts (2) according to the inclination angle of the slewing bearing (3) through trigonometric functions, and calculates the rotational shear force received by the fixing bolts (2) according to the slewing torque of the slewing bearing (3).

2. A method for testing the load of a swing bearing frame structure according to claim 1, characterized in that: in step I, the bolt strain gauge (1) is embedded at the central axis position of the fixing bolt (2).

3. A method for testing the load of a swing bearing frame structure according to claim 1, characterized in that: in step I, the inclination sensor (5) is a high-precision three-axis inclination sensor.

4. A method for testing the load of a swing bearing frame structure according to claim 1, characterized in that: in step I, select the fixing bolt (2) with the largest force on the outer ring of the slewing bearing (3) and the fixing bolt (2) at the centrosymmetric position with respect to the fixing bolt (2) with the largest force as a group of corresponding bolts, and measure the force conditions of this group of corresponding bolts.

5. A method for testing the load of a swing bearing frame structure according to claim 4, characterized in that: the tangent line of the circle where the fixing bolts (2) are located on the outer ring of the slewing bearing, and this tangent line is also perpendicular to the line connecting the center of gravity of the upper part and the force application point of the bucket load. Select the fixing bolt at position A closest to the tangent point of this tangent line as the fixing bolt (2) with the largest force on the outer ring of the slewing bearing (3).

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