Structural member fatigue reliability test device and test method for loader

Abstract

The present application belongs to the technical field of fatigue test, and particularly relates to a loader structural part fatigue reliability test device and test method, the test device comprising a front rigid bridge, a front rigid bridge support, a rear rigid bridge, a rear rigid bridge support, a traction oil cylinder and a traction oil cylinder support; the front rigid bridge is symmetrically provided with a front frame connecting structure and symmetrically provided with a front ear plate, two front frame connecting structures are located between two front ear plates, the round shaft portions at the two ends of the front rigid bridge are respectively supported on a front rigid bridge support, and the front rigid bridge and the front rigid bridge support are gap fitted; the rear rigid bridge is symmetrically provided with a rear frame connecting structure and symmetrically provided with a rear ear plate, two rear frame connecting structures are located between two rear ear plates, the two ends of the rear rigid bridge are respectively supported on a rear rigid bridge support, and the rear rigid bridge and the rear rigid bridge support are gap fitted. The test device can effectively verify the fatigue reliability of the structural part of the loader under single working condition, and provide test support for finite element analysis.

Description

Technical Field

[0001] This invention belongs to the field of fatigue testing technology, specifically relating to a fatigue reliability testing device and method for structural components used in loaders. Background Technology

[0002] For fatigue testing of structural components used in loaders, the industry mainly relies on finite element analysis for prediction, with limited research on experimental verification. Currently, the main method for fatigue testing of loader structural components is to apply reverse loading to the bucket using actuators.

[0003] However, due to the single point of action, reverse loading cannot achieve decoupling of the loading force, thus failing to meet the fatigue reliability verification requirements of loader structural components under single working conditions. Furthermore, reverse loading typically employs imported actuators, resulting in high costs. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, this invention provides a fatigue reliability testing device and method for loader structural components. This device can verify not only the reliability of the loader's working device but also the reliability of the loader's front and rear frame structural components. By employing a decoupled design for traction and lifting forces, the fatigue reliability of the loader's structural components under single working conditions can be effectively verified, providing experimental support for finite element analysis.

[0005] The present invention is achieved through the following technical solution: a fatigue reliability testing device for structural components of a loader, comprising a front rigid axle, a front rigid axle support, a rear rigid axle, a rear rigid axle support, a traction cylinder, and a traction cylinder support;

[0006] The front rigid axle is symmetrically provided with a front frame connection structure and symmetrically provided with front ear plates. The two front frame connection structures are located between the two front ear plates. The round shafts at both ends of the front rigid axle are respectively supported on a front rigid axle support, and the front rigid axle and the front rigid axle support are clearance-fitted. The front frame connection structure is used to fix the front frame of the loader.

[0007] The rear rigid axle is symmetrically provided with a rear frame connection structure and symmetrically provided with rear ear plates. The two rear frame connection structures are located between the two rear ear plates. The two ends of the rear rigid axle are respectively supported on a rear rigid axle support, and the rear rigid axle and the rear rigid axle support are clearance-fitted. The rear frame connection structure is used to fix the rear frame of the loader.

[0008] The two front lugs of the front rigid axle and the two rear lugs of the rear rigid axle are respectively hinged to the piston rod of a traction cylinder, and the bottom of each traction cylinder is hinged to the traction cylinder support.

[0009] It also includes a bucket mounting bracket located in front of the front rigid axle for securing the loader bucket.

[0010] In some embodiments, a T-shaped platform is also included, wherein the bucket mounting base, the front rigid bridge support, the rear rigid bridge support, and the traction cylinder support are all movably mounted on the T-shaped platform.

[0011] In some embodiments, a tail locking device for securing the loader's rear frame is also included, the tail locking device being connected to the tail of the loader's rear frame.

[0012] In some embodiments, the rear rigid bridge is a square steel structure, and the rear rigid bridge support is provided with slots II that match the shape of the rear rigid bridge.

[0013] In some embodiments, the rear rigid axle support is connected to the rear rigid axle connection between the rear frame connection structure and the rear lug.

[0014] In some embodiments, the front frame of the loader is bolted to the front frame connection structure, and the rear frame of the loader is bolted to the rear frame connection structure.

[0015] The present invention also provides a fatigue reliability test method for structural components of a loader, including the above-mentioned fatigue reliability test device for structural components of a loader; fixing the front frame of the loader to the front frame connecting structure, fixing the rear frame of the loader to the rear frame connecting structure, and fixing the bucket of the loader to the bucket fixing seat;

[0016] Verify the fatigue reliability of structural components under traction conditions: The tipping cylinder and boom cylinder of the loader working device do not operate, and the traction cylinder operates continuously under the control of the load-sensitive valve. The pressure of the traction cylinder is set according to a sine curve.

[0017] Verify the fatigue reliability of structural components under the lifting force condition of the tipping bucket: The traction cylinder and the boom cylinder of the loader working device do not operate, and the tipping bucket cylinder operates continuously through the load-sensitive valve. The pressure of the tipping bucket cylinder is set according to the sine curve.

[0018] Verify the fatigue reliability of the structural components under boom lifting force conditions: neither the traction cylinder nor the dump cylinder of the loader working device operates, and the boom cylinder operates continuously under the control of a load-sensitive valve. The pressure of the boom cylinder is set according to a sine curve.

[0019] The beneficial effects of this invention are as follows: This test apparatus, through the tipping cylinder, boom cylinder, and traction cylinder, applies positive loading to the test specimen, effectively decoupling the loader's traction force and digging force. This verifies the fatigue reliability of the loader on a single structural component and provides experimental support for finite element analysis. This design uses a conventional cylinder loading method, replacing dedicated actuators, resulting in low testing costs. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of the present invention;

[0021] Figure 2 This is a schematic diagram of the present invention during testing;

[0022] Figure 3 This is a force analysis diagram during the experimental process of this invention;

[0023] In the diagram, 1. T-shaped platform, 2. Bucket mounting base, 3. Front rigid axle, 3-1. Front frame connection structure, 3-2. Front lug plate, 4. Front rigid axle support, 4-1. Slot I, 5. Rear rigid axle, 5-1. Rear frame connection structure, 5-2. Rear lug plate, 6. Rear rigid axle support, 6-1. Slot II, 7. Bucket cylinder, 8. Boom cylinder, 9. Traction cylinder, 10. Traction cylinder support, 10-1. Support lug plate, 11. Tail locking device. Detailed Implementation

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0025] like Figures 1 to 3 As shown, a fatigue reliability testing device for structural components of a loader includes a bucket mounting base 2, a front rigid axle 3, a front rigid axle support 4, a rear rigid axle 5, a rear rigid axle support 6, a traction cylinder 9, and a traction cylinder support 10. The bucket mounting base 2 is used to fix the loader's bucket. The front rigid axle 3 is supported on the front rigid axle support 4 for connection to the loader's front frame, and the front rigid axle 3 can move horizontally back and forth and rotate relative to the front rigid axle support 4. The rear rigid axle 5 is supported on the rear rigid axle support 6 for connection to the loader's rear frame, and the rear rigid axle 5 can move horizontally back and forth relative to the rear rigid axle support 6. The relative movement of the front rigid axle 3 and the relative movement of the rear rigid axle 5 are both driven by the traction cylinder 9.

[0026] Specifically, the front rigid axle 3 is symmetrically provided with front frame connecting structures 3-1, and the front frame of the loader is fixed to the front frame connecting structures 3-1 by bolts. The front rigid axle 3 is also symmetrically provided with front ear plates 3-2, and the two front frame connecting structures 3-1 are located between the two front ear plates 3-2. The two ends of the front rigid axle 3 are round shaft structures, and the front rigid axle support 4 is provided with slots I4-1. The two ends of the front rigid axle 3 are installed in the slots I4-1 of the two front rigid axle supports 4. The diameter of the slots I4-1 is slightly larger than the round shaft structures at the ends of the front rigid axle 3. Two traction cylinder supports 10 are provided at the rear of the front rigid axle 3. One front ear plate 3-2 on the front rigid axle 3 corresponds to one traction cylinder support 10. The traction cylinder support 10 is provided with support ear plates 10-1, which are used to hinge with the cylinder bottom of the traction cylinder 9. The piston rod of the traction cylinder 9 is hinged to the front ear plate 3-2. Under the loading action of the traction cylinder 9, the front rigid axle 3 can move back and forth and rotate relative to the front rigid axle support 4.

[0027] The rear rigid axle 5 is symmetrically equipped with rear frame connection structures 5-1, and the loader's rear frame is fixed to the rear frame connection structures 5-1 by bolts. The rear rigid axle 5 is also symmetrically equipped with rear ear plates 5-2, with the two rear frame connection structures 5-1 located between the two rear ear plates 5-2. The rear rigid axle 5 is a square steel structure, and the rear rigid axle support 6 has a slot II 6-1 that matches the shape of the rear rigid axle 5. The size of the slot II 6-1 is slightly larger than the size of the rear rigid axle 5. Two traction cylinder supports 10 are located behind the rear rigid axle 5. One rear ear plate 5-2 on the rear rigid axle 5 corresponds to one traction cylinder support 10. The traction cylinder support 10 has a support ear plate 10-1, which is used to hinge with the cylinder bottom of the traction cylinder 9. The piston rod of the traction cylinder 9 is hinged with the rear ear plate 5-2. Under the loading action of the traction cylinder 9, the rear rigid axle 5 can move back and forth relative to the rear rigid axle support 6.

[0028] In some embodiments, depending on the structure of the loader, the rear rigid axle support 6 is connected to the rear rigid axle 5 between the rear frame connection structure 5-1 and the rear lug 5-2.

[0029] In some embodiments, the device also includes a T-shaped platform 1, on which the bucket mounting base 2, the front rigid bridge support 4, the rear rigid bridge support 6, and the traction cylinder support 10 are all movably mounted. The mounting of the above components on the T-shaped platform 1 facilitates the adjustment of the position of each component. The installation position of the components can be flexibly adjusted on the T-shaped platform 1 according to different models of loaders, so that the test device can meet the fatigue test requirements of different models of loaders.

[0030] In some embodiments, a tail locking device 11 for securing the loader's rear frame is also included, the tail locking device 11 being connected to the rear of the loader's rear frame. The tail locking device 11 acts as a counterweight to prevent the test specimen from tipping over during the test.

[0031] The existing process for finite element analysis of structural components for loaders is as follows:

[0032] I. Verify the fatigue reliability of structural components under traction conditions:

[0033] Under this working condition, the tipping cylinder 7 and boom cylinder 8 are in a "locked" state (the load-sensitive valve is in the neutral position). The theoretical design value of the traction force of the loader under test is converted into the system pressure P1 of the four traction cylinders 9. The traction cylinders 9 are controlled by the load-sensitive valve, and the system pressure of the traction cylinders 9 is set according to a sine curve. For example, in computer simulation, the maximum peak value of the sine curve of the system pressure of the traction cylinders 9 is set to P1 (that is, the system pressure P1 of the four traction cylinders 9 converted from the theoretical design value of the traction force). The period T of the sine curve is 1s. In a 30s working cycle, the loader pushes the material (traction force) for 3s. It can be deduced that in one test cycle T (1s), the actual working time of the loader is 10s. Then, based on the test results, the actual life of the loader under traction conditions can be calculated.

[0034] II. Verification of the fatigue reliability of structural components under the tipping bucket lifting force condition:

[0035] Under this working condition, boom cylinder 8 and traction cylinder 9 are in a "locked" state (load-sensitive valve is in the neutral position). Based on the theoretical working system pressure P2 of the hydraulic system of the loader under test, system pressure P2 is applied to tipping cylinder 7. Tipping cylinder 7 is controlled by the load-sensitive valve, and the system pressure of tipping cylinder 7 is set according to a sine curve. For example, in computer simulation, the maximum peak value of the sine curve of the system pressure of tipping cylinder 7 is set to P2 (that is, the aforementioned working system pressure P2), and the period T of the sine curve is 1s. In a 30s working cycle, the loader tipps (tip lifting force) for 3s. It can be deduced that in one test cycle T (1s), the actual working time of the loader is 10s. Based on the test results, the actual life of the loader under the tipping lifting force condition can be calculated.

[0036] III. Verification of the fatigue reliability of structural components under boom lifting force conditions:

[0037] Under this condition, the tipping cylinder 7 and the traction cylinder 9 are in a "locked" state (the load-sensitive valve is in the neutral position). Based on the theoretical working system pressure P3 of the tested loader's hydraulic system (the theoretical working system pressure P3 here is the same as the aforementioned theoretical working system pressure P2, but different notations are used for ease of subsequent description), system pressure P3 is applied to the boom cylinder 8. The boom cylinder 8 is controlled by the load-sensitive valve, and the system pressure is set according to a sine curve. For example, in computer simulation, the maximum peak value of the sine curve of the system pressure of the boom cylinder 8 is set to P3 (i.e., the aforementioned working system pressure P3), and the period T of the sine curve is 1 second. Within a 30-second working cycle, the bucket tipping (boom lifting force) occurs for 3 seconds. Therefore, within one test cycle T (1 second), the actual working time of the loader is calculated to be 10 seconds. Based on the test results, the actual lifespan of the loader under boom lifting force conditions can be calculated.

[0038] This invention also provides a fatigue reliability test method for structural components of loaders, which can effectively verify the fatigue reliability of structural components of loaders under single working conditions and provide experimental support for finite element analysis. It includes the aforementioned fatigue reliability test device for structural components of loaders; the front frame of the loader is fixed to the front frame connecting structure 3-1, the rear frame of the loader is fixed to the rear frame connecting structure 5-1, and the bucket of the loader is fixed to the bucket fixing seat 2;

[0039] Verification of structural fatigue reliability under traction conditions: The dump cylinder and boom cylinder of the loader working device do not operate, and the traction cylinder 9 operates continuously under the control of the load-sensitive valve. The pressure of the traction cylinder 9 is set according to the parameters set during the finite element analysis.

[0040] Verify the fatigue reliability of the structural components under the lifting force condition of the bucket: neither the traction cylinder 9 nor the boom cylinder of the loader working device moves, and the bucket cylinder moves continuously under the control of the load-sensitive valve. The pressure of the bucket cylinder is set according to the parameters set during the finite element analysis.

[0041] Verification of structural fatigue reliability under boom lifting force conditions: neither the traction cylinder 9 nor the dump cylinder of the loader working device operates. The boom cylinder operates continuously under the control of the load-sensitive valve. The pressure of the boom cylinder is set according to the parameters set during the finite element analysis.

[0042] This test apparatus is used to obtain the service life of structural components for loaders through actual simulation tests. The service life obtained from the actual tests is compared with the service life obtained from the computer simulation, thereby verifying whether the finite element analysis process is reasonable.

[0043] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall fall within the scope of the technical solution of the present invention.

Claims

1. A test method using a fatigue reliability test device for structural members of a loader, characterized by: The loader structure fatigue reliability test device includes a front rigid bridge (3), a front rigid bridge support (4), a rear rigid bridge (5), a rear rigid bridge support (6), a traction oil cylinder (9), and a traction oil cylinder support (10); The front rigid bridge (3) is symmetrically provided with front frame connecting structures (3-1) and front ear plates (3-2), the two front frame connecting structures (3-1) are located between the two front ear plates (3-2), the circular shaft portions at the two ends of the front rigid bridge (3) are respectively supported on the front rigid bridge supports (4), and the front rigid bridge (3) is in clearance fit with the front rigid bridge supports (4), and the front frame connecting structures (3-1) are used for fixing the front frame of the loader; The rear rigid bridge (5) is symmetrically provided with rear frame connecting structures (5-1) and rear ear plates (5-2), the two rear frame connecting structures (5-1) are located between the two rear ear plates (5-2), the two ends of the rear rigid bridge (5) are respectively supported on the rear rigid bridge supports (6), and the rear rigid bridge (5) is in clearance fit with the rear rigid bridge supports (6), and the rear frame connecting structures (5-1) are used for fixing the rear frame of the loader; The two front ear plates (3-2) of the front rigid bridge (3) and the two rear ear plates (5-2) of the rear rigid bridge (5) are respectively hinged to the piston rods of the traction oil cylinders (9), and the cylinder bottoms of the traction oil cylinders (9) are hinged to the traction oil cylinder supports (10); The test device further comprises a bucket fixing seat (2) arranged in front of the front rigid bridge (3) and used for fixing the bucket of the loader; The test method is as follows: The front frame of the loader is fixed on the front frame connecting structures (3-1), the rear frame of the loader is fixed on the rear frame connecting structures (5-1), and the bucket of the loader is fixed on the bucket fixing seat (2); The structure fatigue reliability of the structure under the traction working condition is verified: the tipping cylinder and the boom cylinder of the loader working device are not actuated, the traction oil cylinder (9) is continuously actuated through the load-sensitive valve control, and the pressure of the traction oil cylinder (9) is set according to a sine curve; The structure fatigue reliability of the structure under the tipping cylinder rising force working condition is verified: the traction oil cylinder (9) and the boom cylinder of the loader working device are not actuated, the tipping cylinder is continuously actuated through the load-sensitive valve control, and the pressure of the tipping cylinder is set according to a sine curve; The structure fatigue reliability of the structure under the boom cylinder rising force working condition is verified: the traction oil cylinder (9) and the tipping cylinder of the loader working device are not actuated, the boom cylinder is continuously actuated through the load-sensitive valve control, and the pressure of the boom cylinder is set according to a sine curve.

2. The test method of claim 1, wherein: The test device further comprises a T-shaped table (1), and the bucket fixing seat (2), the front rigid bridge supports (4), the rear rigid bridge supports (6), and the traction oil cylinder supports (10) are movably installed on the T-shaped table (1).

3. The test method of claim 1, wherein: The test device further comprises a tail locking device (11) used for fixing the rear frame of the loader, and the tail locking device (11) is connected with the tail of the rear frame of the loader.

4. The test method of claim 1, wherein: The rear rigid bridge (5) is a square steel structure, and the rear rigid bridge support (6) is provided with a slot hole II (6-1) matched with the shape of the rear rigid bridge (5).

5. The test method of claim 1, wherein: The rear rigid axle (5) is connected between the rear rigid axle support (6) and the rear frame connecting structure (5-1) and the rear ear plate (5-2).

6. The test method of claim 1, wherein: The front frame of the loader is bolted to the front frame connecting structure (3-1), and the rear frame of the loader is bolted to the rear frame connecting structure (5-1).

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