Fatigue reliability test device and loading method for key components of loaders

Abstract

The present invention discloses a fatigue reliability test device and loading method for a loader's key components, comprising a front frame support, a rear frame support, an actuator and a rigid wall; the front frame support is used to support the front frame and enable the front frame to move with the loader when the loader moves; the rear frame support is used to support the rear frame; one end of the actuator is adjustably mounted on the rigid wall, and the other end is connected to the loader bucket. The fatigue reliability test device for a loader's key components of the present invention has adjustable spacing between various structures, and is suitable for fatigue testing of different types of loader working devices. The loading method for a loader's working device fatigue reliability test of the present invention uses a force sensor to obtain hinge force, and the obtained actuator loading force time history is both relatively consistent with actual damage and convenient for loading in a laboratory.

Description

Technical Field

[0001] The invention relates to a fatigue reliability test device and a loading method for a key component of a loader, belonging to the technical field of fatigue testing. Background Art

[0002] As the foundational structure supporting the working mechanism, the loader's front frame must withstand tensile, compressive, bending, torsional, and impact loads from all directions. Currently, while there are numerous fatigue testing devices for loader working mechanisms, few are specifically designed for fatigue testing the loader's front frame and its loading methods. Typically, when fatigue testing the working mechanism, the front frame's hinge points are rigidly fixed. This results in significant differences in the force and motion of the front frame compared to actual operating conditions, making it impossible to simultaneously perform fatigue testing on the working mechanism and the front frame.

[0003] Existing load spectrum processing techniques for loader tests generally generate test spectra based on the equivalent relationship between the bending moment of the boom section and the equivalent external force. This method only performs equivalent calculations at specific locations, making it relatively accurate for specific locations and not universally applicable. Furthermore, some existing load spectrum processing methods introduce errors in global fatigue assessment of the structure, or the processed load spectra are not suitable for laboratory loading. Therefore, improvements are needed in the collection and processing of loader load spectra. Summary of the Invention

[0004] In view of the problems existing in the above-mentioned prior art, the present invention provides a fatigue reliability testing device for key components of a loader, which can not only be used for fatigue testing of the loader's front frame, but also can complete fatigue testing of the loader's front frame and working device at the same time.

[0005] The present invention also provides a loading method for fatigue reliability testing of key components for loaders, which can facilitate bench testing of sinusoidal loading spectrum blocks. The obtained actuator loading force time history is relatively consistent with the actual damage, which is convenient for loading in the laboratory.

[0006] In order to achieve the above-mentioned object, the present invention adopts a fatigue reliability test device for a loader key component, comprising a front frame support, a rear frame support, an actuator and a rigid wall;

[0007] The two front frame supports are symmetrically arranged, and the front frame supports include a front support body, on which a front frame connecting plate, a cylinder and a V-shaped fixing block are provided. The two lower V-shaped fixing blocks are fixed to the front support body, the cylinder is fixed between the two lower V-shaped fixing blocks, and the two upper V-shaped fixing blocks are fixed to the bottom of the front frame connecting plate. The cylinder is clearance-matched with the two upper V-shaped fixing blocks. The front frame support is used to support the front frame and enable the front frame to move when the loader moves.

[0008] The two rear frame supports are symmetrically arranged, and the rear frame supports include a rear support body, on which a rear frame connecting plate and a rectangular connecting square steel are provided, and the rectangular connecting square steel is provided with a rectangular connecting block and a slot matching the shape of the rectangular connecting block, and the rear frame supports are used to support the rear frame;

[0009] One end of the actuator is adjustably mounted on a rigid wall, and the other end is connected to a loader bucket.

[0010] As an improvement, the actuator includes a hydraulic cylinder, an actuator fixing seat and a bucket fixing seat;

[0011] Both ends of the hydraulic cylinder are connected to the actuator fixing seat and the bucket fixing seat through spherical hinge joints respectively, and the hydraulic cylinder can rotate around the spherical hinge joints.

[0012] As an improvement, the actuator fixing seat is installed on the rigid wall, and a plurality of through holes are opened on the actuator fixing seat.

[0013] As an improvement, a plurality of mounting holes are opened on the rigid wall.

[0014] As an improvement, a triangular reinforcement plate is installed between the rear frame connecting plate and the rectangular connecting square steel.

[0015] As an improvement, it further comprises a base, on which a plurality of T-slots are provided, and the rigid wall, the front frame support and the rear frame support are all movably mounted on the base by bolts.

[0016] In addition, the present invention also provides a method for loading a loader's key component fatigue reliability test, using the aforementioned loader's key component fatigue reliability test device;

[0017] First, the bucket tooth tip load spectrum is obtained by collecting data such as the hinge force, system pressure, and cylinder displacement during the test.

[0018] Then, by extracting the vertical and horizontal loads from the bucket tooth tip load spectrum during the digging process, the root mean square values of the vertical and horizontal loads in each digging process are calculated. The root mean square values of the vertical and horizontal loads in all digging processes are averaged to obtain the magnitude of the vertical and horizontal loads on the bucket tooth tip during the digging process, thereby determining the loading angle of the test actuator.

[0019] Finally, the oblique loading load spectrum of the test actuator is determined based on the vertical load of the bucket tooth tip digging process and the loading angle of the test actuator, and the sinusoidal loading spectrum block of the bench test is further determined.

[0020] As an improvement, the time history of the hinge force between the left boom and the bucket, the time history of the hinge force between the right boom and the bucket, and the time history of the pull rod force in the local coordinate system are determined based on the force sensor data;

[0021] Determine the displacement time history of the boom cylinder and the rocker arm cylinder during the movement process according to the displacement sensor data;

[0022] According to the displacement time history of the boom cylinder and the rocker cylinder, the included angle between the Y axis of the local coordinate system and the vertical direction at the zero time, the angle time history between the bucket and the ground, and the angle time history between the drawbar and the Y axis of the local coordinate system are determined;

[0023] Determine the time history of the component forces in each direction of the tie rod force in the local coordinate system based on the time history of the angle between the tie rod and the Y axis of the local coordinate system;

[0024] Determine the bucket tooth tip load time history in the local coordinate system based on the hinge force time history between the left boom and bucket, the hinge force time history between the right boom and bucket, and the time history of the components of the pull rod force in each direction.

[0025] The bucket tooth tip load time history in the entire motion process in the global coordinate system is determined based on the bucket tooth tip load time history in the local coordinate system, the bucket and ground angle time history, and the angle between the local coordinate system Y axis and the vertical direction at the zero time position;

[0026] The bucket tooth tip load time history during the excavation process is extracted based on the bucket tooth tip load time history during the entire motion process in the global coordinate system;

[0027] Determine the loading angle of the test actuator based on the bucket tooth tip load time history during the digging process;

[0028] Determine the time history of the test actuator loading force based on the time history of the bucket tooth tip vertical load and the loading angle of the test actuator during the excavation process;

[0029] Singular values were removed from the test data to obtain a series of load cycles with different amplitudes and means. The load amplitudes were divided into multiple unequal intervals and the acceleration spectrum of the structure was compiled using the relative equivalent damage principle. According to the operating characteristics of the loader, a "low-high-low" loading sequence was used to simulate the actual operating load to obtain the test loading spectrum block. The loading wave was a sine wave.

[0030] The obtained test actuator loading load spectrum is loaded onto the above-mentioned loader key component fatigue reliability test device through the actuator.

[0031] Compared with the prior art, the fatigue reliability test device for the loader's key components of the present invention has a front frame support that ensures the front frame moves with the loader when the loader is in motion, and the front and rear frame supports can simulate the tire's support for the front and rear frames. The loading hydraulic cylinder on the actuator can rotate around the spherical hinge joints distributed at its front and rear ends, and can load the combined force of the vertical load and horizontal load to which the loader's working device is actually subjected to onto the loader bucket. It can not only be used for fatigue testing of the loader's front frame, but can also complete fatigue testing of the loader's front frame and working device at the same time, and make the fatigue reliability test results of the loader's front frame and working device closer to the actual working results, reduce test errors, and better provide test support for the fatigue reliability simulation of the loader's key components. The fatigue reliability test device for the loader's key components of the present invention has adjustable spacing between each structure, and is suitable for fatigue testing of working devices of different models of loaders.

[0032] The loading method for fatigue reliability testing of a working device for a loader of the present invention uses a force sensor to obtain hinge force, determines the loading angle of the test actuator from the load time history of the bucket tooth tip during the digging process, and determines the loading time history of the actuator from the vertical load time history of the bucket tooth tip during the digging process and the loading angle of the test actuator. This method is not only highly operational, but the obtained actuator loading force time history is relatively consistent with actual damage, and is convenient for loading in the laboratory. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a structural schematic diagram of a fatigue reliability test device for a loader's key components according to the present invention;

[0034] Figure 2 It is a structural schematic diagram of the front frame support in the fatigue reliability test device for key components of a loader according to the present invention;

[0035] Figure 3 It is a structural schematic diagram of the rear frame support in the fatigue reliability test device for key components of a loader according to the present invention;

[0036] Figure 4 It is a structural schematic diagram of the actuator in the fatigue reliability test device for key components of a loader according to the present invention;

[0037] Figure 5 This is a schematic diagram of the installation structure of the fatigue reliability test device for the key components of a loader according to the present invention;

[0038] Figure 6 It is a flow chart of the method for processing the load spectrum of the loader test of the present invention;

[0039] Figure 7 It is a schematic diagram of the local coordinate system of the present invention;

[0040] Figure 8 It is a schematic diagram of the global coordinate system of the present invention;

[0041] Figure 9 Schematic diagram of bucket tooth tip load calculation in the local coordinate system of the present invention;

[0042] Figure 10 1. It is a schematic diagram of the calculation of the loading force of the test actuator of the present invention;

[0043] Figure 11 It is a loading schematic diagram of the present invention;

[0044] Figure 12 is the load-time history of the loading force F of the actuator of the present invention;

[0045] In the figure: 1. Base, 1-1. T-slot, 2. Rigid wall, 2-1. Mounting hole, 3. Actuator, 3-1. Hydraulic cylinder, 3-2. Spherical hinge joint, 3-3. Actuator fixing seat, 3-4. Bucket fixing seat, 4. Front frame support, 4-1. Front frame connecting plate, 4-2. Cylinder, 4-3. V-shaped fixing block, 4-4. Front support body, 5. Rear frame support, 5-1. Rear frame connecting plate, 5-2. Rectangular connecting square steel, 5-3. Rectangular connecting block, 5-4. Triangular reinforcement plate, 5-5. Rear support body, 6. Bucket, 7. Draw rod, 8. Left boom, 9. Rocker cylinder, 10. Right boom, 11. Boom cylinder. DETAILED DESCRIPTION

[0046] To make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below. However, it should be understood that the specific embodiments described herein are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0047] Unless otherwise defined, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention pertains. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0048] like Figure 1 、 Figure 2 and Figure 3 As shown, a fatigue reliability test device for a loader's key components includes a front frame support 4, a rear frame support 5, an actuator 3, and a rigid wall 2;

[0049] The two front frame supports 4 are symmetrically arranged, and each front frame support 4 includes a front support body 4-4, on which a front frame connecting plate 4-1, a cylinder 4-2 and four V-shaped fixing blocks 4-3 are provided. The two lower V-shaped fixing blocks 4-3 are fixed to the front support body 4-4, and can be fixed by welding or bolting. The cylinder 4-2 is fixed between the two lower V-shaped fixing blocks 4-3, and the two upper V-shaped fixing blocks 4-3 are fixed to the bottom of the front frame connecting plate 4-1. The cylinder 4-2 is clearance-fitted with the two upper V-shaped fixing blocks 4-3. The front frame support 4 is used to support the front frame and enable the front frame to move when the loader moves;

[0050] The two rear frame supports 5 are symmetrically arranged, and the rear frame supports 5 include a rear support body 5-5, on which a rear frame connecting plate 5-1 and a rectangular connecting square steel 5-2 are provided. The rectangular connecting square steel 5-2 is symmetrically provided with a rectangular connecting block 5-3 perpendicular thereto, a triangular reinforcing plate 5-4, and a slot matching the shape of the rectangular connecting block 5-3. The slot ensures that the rectangular connecting block 5-3 can be effectively installed on the rectangular connecting square steel 5-2, and the cooperation of the rectangular connecting square steel 5-2, the rectangular connecting block 5-3, and the triangular reinforcing plate 5-4 improves the stability of the overall structure. The rear frame support 5 is used to support the rear frame, and the front and rear frame supports can simulate the supporting effect of the tire on the front and rear frames.

[0051] One end of the actuator 3 is adjustably mounted on the rigid wall 2 , and the other end is connected to the loader bucket.

[0052] As an improvement of the embodiment, Figure 1 、 Figure 4 As shown, the actuator 3 includes a hydraulic cylinder 3-1, a spherical hinge joint 3-2, an actuator fixing seat 3-3 and a bucket fixing seat 3-4;

[0053] The two ends of the hydraulic cylinder 3-1 are respectively connected to the actuator fixing seat 3-3 and the bucket fixing seat 3-4 through the spherical hinge joint 3-2. The hydraulic cylinder 3-1 can rotate around the spherical hinge joint 3-2 distributed at its front and rear ends, and can load the combined force of the vertical load and horizontal load actually exerted on the loader working device onto the loader bucket; the actuator fixing seat 3-3 is used to connect the actuator 3 and the rigid wall 2, and a series of through holes of equal spacing and size are opened on the actuator fixing seat 3-3. The bucket fixing seat 3-4 is used to connect the hydraulic cylinder 3-1 and the bucket 6.

[0054] As an improvement of the embodiment, Figure 1 、 Figure 4As shown, the actuator fixing seat 3-3 is provided with a series of through holes of equal spacing and size. Furthermore, the rigid wall 2 is provided with a plurality of mounting holes 2-1 that match the through holes on the actuator fixing seat 3-3. By cooperating with the through holes and the mounting holes 2-1, the connection position of the actuator 3 and the rigid wall 2 can be effectively adjusted.

[0055] As an improvement of the embodiment, Figure 5 As shown, it also includes a base 1, on which are provided a plurality of rows of T-shaped slots 1-1 arranged in parallel with equal spacing;

[0056] The rigid wall 2, the front frame support 4 and the rear frame support 5 are all movably mounted on the base 1 by means of T-bolts, ensuring that the spacing between the components can be adjusted, and are suitable for fatigue tests of working devices of different models of loaders.

[0057] In addition, the present invention also provides a method for loading a loader's key component fatigue reliability test, using the aforementioned loader's key component fatigue reliability test device;

[0058] First, the bucket tooth tip load spectrum is obtained by collecting data such as the hinge force, system pressure, and cylinder displacement during the test.

[0059] Then, by extracting the vertical and horizontal loads from the bucket tooth tip load spectrum during the digging process, the root mean square values of the vertical and horizontal loads in each digging process are calculated. The root mean square values of the vertical and horizontal loads in all digging processes are averaged to obtain the magnitude of the vertical and horizontal loads on the bucket tooth tip during the digging process, thereby determining the loading angle of the test actuator.

[0060] Finally, the oblique loading load spectrum of the test actuator is determined based on the vertical load of the bucket tooth tip digging process and the loading angle of the test actuator, and the sinusoidal loading spectrum block of the bench test is further determined.

[0061] During the test, the actuator 3 obliquely placed between the rigid wall 2 and the bucket 6 provides the loading force. The loading position in the excavation condition is at the front end position of the loader bucket cutting edge in the front-to-back direction, and the loading point in the left-to-right direction is located in the middle position of the bucket 6.

[0062] When actuator 3 extends, downward pressure is applied. The horizontal and vertical components simulate the insertion and breakout resistance of a wheel loader, respectively. When actuator 3 retracts, it provides an upward lifting force, simulating the compressive force exerted by the pile on the bucket bottom surface during insertion due to the horizontal inclination of the bucket bottom surface. The large and small chambers of the boom cylinders on both sides are connected, and the locking valves are locked. During the test, internal leakage and settlement are observed. Once a certain amount is reached, the loader is used to increase pressure.

[0063] During fatigue testing, dynamic stress testing equipment, such as force sensors, is used at multiple time points to collect dynamic stress data on the front frame. The locations of stress measurement points on the front frame should be determined based on finite element analysis results and after-sales service records of similar structural products. Stress measurement points should include stress concentration points and potential danger points.

[0064] like Figure 6-Figure 12 As shown, the specific process is:

[0065] Determine the time history of the hinge force between the left boom 8 and the bucket, the time history of the hinge force between the right boom 10 and the bucket, and the time history of the pull rod force in the local coordinate system based on the force sensor data;

[0066] The local coordinate system is Figure 7 As shown, the center of the hinge point between the boom and the bucket is the origin, the line connecting the origin, the tie rod 7 and the bucket hinge point is the positive direction of the Y axis, the line passing through the origin and perpendicular to the Y axis is the X axis, and the line from the origin to the tie rod 7 is the positive direction of the X axis. The Z axis is determined by the right-hand rule;

[0067] The global coordinate system is Figure 8 As shown, the bucket force point is taken as the origin, the direction parallel to the ground and pointing to the pull rod is taken as the positive direction of the X axis, the vertical upward direction is taken as the positive direction of the Y axis, and the Z axis is determined by the right-hand rule;

[0068] The angle is positive if it rotates counterclockwise and negative if it rotates clockwise.

[0069] Determine the displacement time history of the boom cylinder 11 and the rocker cylinder 9 based on the displacement sensor data;

[0070] Establish the dynamic model of the loader working device in the dynamics software;

[0071] Adjust the dynamic model to the zero-time position of the boom cylinder 11 and the rocker cylinder 9;

[0072] Get the angle between the Y axis of the local coordinate system and the vertical direction at time zero;

[0073] The kinematic simulation is performed based on the displacement time history of the boom cylinder 11 and the rocker cylinder 9 to obtain the angle time history between the bucket and the ground, and the angle time history between the tie rod 7 and the Y axis of the local coordinate system;

[0074] The time history of the component forces of the pull rod force in each direction in the local coordinate system is determined based on the time history of the angle between the pull rod 7 and the Y axis of the local coordinate system, as shown in (1) to (2):

[0075] Fx = F * sinA; (1)

[0076] Fy = F * cosA; (2)

[0077] Where Fx is the X-axis component of the tie rod force in the local coordinate system, Fy is the Y-axis component of the tie rod force in the local coordinate system, F is the tie rod force, and A is the angle between the tie rod and the Y-axis of the local coordinate system;

[0078] like Figure 9 The calculation of bucket tooth tip load in the local coordinate system is shown as follows:

[0079] Considering the mechanical equilibrium equations in the local coordinate system as shown in (3) to (7),

[0080] ∑Fx = 0: Fcx + Fax + Fbx + Fix = 0; (3)

[0081] ∑Fy = 0: -Fcy + Fay + Fby + Fiy = 0 (4)

[0082] ∑Mx = 0: Mcx + Fby * L2 – Fay * L2 = 0; (5)

[0083] ∑My = 0: Mcy + Fax * L2 – Fbx * L2 = 0; (6)

[0084] ∑Mz = 0: Mcz + (Fay + Fby + Fiy) * L3 – (Fax + Fbx) * L4 – Fix * (L1+ L4) = 0; (7)

[0085] Among them, a refers to the hinge point between the boom (left) and the bucket, b refers to the hinge point between the boom (right) and the bucket, i refers to the hinge point between the drawbar and the bucket, c refers to the force point of the bucket, Fax is the component of the force at the hinge point a on the X axis in the local coordinate system, Fay is the component of the force at the hinge point a on the Y axis in the local coordinate system, Fbx is the component of the force at the hinge point b on the X axis in the local coordinate system, Fby is the component of the force at the hinge point b on the Y axis in the local coordinate system, Fix is the component of the force at the hinge point i on the X axis in the local coordinate system, and Fiy is the component of the force at the hinge point i on the Y axis in the local coordinate system , Fcx is the component of the bucket force on the X axis in the local coordinate system, Fcy is the component of the bucket force on the Y axis in the local coordinate system, Mcx is the torque of the bucket force on the X axis in the local coordinate system, Mcy is the torque of the bucket force on the Y axis in the local coordinate system, Mcz is the torque of the bucket force on the Z axis in the local coordinate system, L1 is the distance from point i to the origin, L2 is the distance from point a to the origin, which is also the distance from point b to the origin, L3 is the projection of the distance from point c to the origin on the X axis, and L4 is the projection of the distance from point c to the origin on the Y axis;

[0086] The bucket tooth tip load in the global coordinate system during the entire motion process is calculated from the bucket tooth tip load in the local coordinate system, as shown in (8) to (12):

[0087] Fx = cos(B + C) * fx + sin(B + C) * fy; (8)

[0088] Fy = -sin(B + C) * fx + cos(B + C) * fy; (9)

[0089] Mx = mx; (10)

[0090] My = my; (11)

[0091] Mz = mz; (12)

[0092] Among them, Fx, Fy, Mx, My, and Mz are the force component along the X-axis, the force component along the Y-axis, the torque around the X-axis, the torque around the Y-axis, and the torque around the Z-axis of the bucket tooth tip in the global coordinate system, respectively; fx, fy, mx, my, and mz are the force component along the X-axis, the force component along the Y-axis, the torque around the X-axis, the torque around the Y-axis, and the torque around the Z-axis of the bucket tooth tip in the local coordinate system, respectively; angle B is the angle between the Y-axis and the vertical direction of the local coordinate system at the moment of zero; angle C is the angle between the bucket and the ground;

[0093] According to the bucket tooth tip load time history during the entire motion process in the global coordinate system, the bucket tooth tip load time history during the excavation process is extracted using the values of Fx and Fy;

[0094] The test actuator is placed obliquely between the rigid wall 2 and the bucket 6 to apply the load. The loading angle of the test actuator is determined mainly by referring to the relationship between the bucket tooth tips Fx and Fy during the excavation process. Figure 12 The load data of Fx and Fy in the ground digging posture in the load spectrum are used to comprehensively determine the loading angle by considering the average value and the root mean square value, and the angle between the actuator placement and the horizontal direction is obtained to be 40.6 degrees.

[0095] Finite element simulation shows that the vertical force has a much greater impact on the structural stress level than the horizontal force. Therefore, Fy is used as the main basis for calculating the loading force. Combined with the loading angle, the test actuator loading force F and the horizontal load Fx are calculated. The load spectrum of the actuator loading force F is as follows: Figure 10 As shown:

[0096] F = Fy / sinD; (13)

[0097] Where F is the loading force of the test actuator, Fy is the component of the bucket tooth tip load along the Y-axis during the digging process in the global coordinate system, and angle D is the angle between the test actuator and the horizontal direction.

[0098] In the test data, some singular values that have little effect on fatigue damage are eliminated to obtain a series of load cycles with different amplitudes and means. The load amplitude is divided into spectra according to multi-level non-uniform intervals, and the acceleration spectrum of the structure is compiled using the relative equivalent damage principle. According to the operating characteristics of the loader, the "low-high-low" loading sequence is used to simulate the real operating load to obtain the test loading spectrum block. The loading wave is a sine wave. The loading schematic diagram is shown as follows: Figure 12 shown.

[0099] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A loading method for fatigue reliability test of key components for loader, characterized in that: Use fatigue reliability test equipment for key components of loaders; The fatigue reliability test device for the loader's key components comprises a front frame support (4), a rear frame support (5), an actuator (3) and a rigid wall (2); the two front frame supports (4) are symmetrically arranged, the front frame support (4) comprises a front support body (4-4), a front frame connecting plate (4-1), a cylinder (4-2) and a V-shaped fixing block (4-3) are provided on the front support body (4-4), the two lower V-shaped fixing blocks (4-3) are fixed on the front support body (4-4), the cylinder (4-2) is fixed between the two lower V-shaped fixing blocks (4-3), the two upper V-shaped fixing blocks (4-3) are fixed to the bottom of the front frame connecting plate (4-1), and the The cylinder (4-2) is clearance-matched with the two V-shaped fixing blocks (4-3) above, and the front frame support (4) is used to support the front frame and enable the front frame to follow the movement of the loader; the two rear frame supports (5) are symmetrically arranged, and the rear frame support (5) includes a rear support body (5-5), and the rear support body (5-5) is provided with a rear frame connecting plate (5-1) and a rectangular connecting square steel (5-2), and the rectangular connecting square steel (5-2) is provided with a rectangular connecting block (5-3) and a slot matching the shape of the rectangular connecting block (5-3), and the rear frame support (5) is used to support the rear frame; one end of the actuator (3) is adjustably mounted on the rigid wall (2), and the other end is connected to the loader bucket; First, the force sensor data is used to determine the time history of the hinge force between the left boom and bucket, the time history of the hinge force between the right boom and bucket, and the time history of the drawbar force in the local coordinate system. The displacement sensor data is used to determine the time history of the boom cylinder displacement and the rocker arm cylinder displacement during movement. The bucket tooth tip load spectrum is obtained by collecting and processing the hinge force, system pressure, and cylinder displacement data. Then, by extracting the vertical and horizontal loads from the bucket tooth tip load spectrum during the digging process, the root mean square values of the vertical and horizontal loads in each digging process are calculated. The root mean square values of the vertical and horizontal loads in all digging processes are averaged to obtain the magnitude of the vertical and horizontal loads on the bucket tooth tip during the digging process, thereby determining the loading angle of the test actuator. Finally, the oblique loading load spectrum of the test actuator is determined based on the vertical load of the bucket tooth tip digging process and the loading angle of the test actuator, and the sinusoidal loading spectrum block of the bench test is further determined.

2. A loading method for fatigue reliability test of a key component for a loader according to claim 1, characterized in that: include: According to the displacement time history of the boom cylinder and the rocker cylinder, the included angle between the Y axis of the local coordinate system and the vertical direction at the zero time, the angle time history between the bucket and the ground, and the angle time history between the drawbar and the Y axis of the local coordinate system are determined; Determine the time history of the component forces in each direction of the tie rod force in the local coordinate system based on the time history of the angle between the tie rod and the Y axis of the local coordinate system; Determine the bucket tooth tip load time history in the local coordinate system based on the hinge force time history between the left boom and bucket, the hinge force time history between the right boom and bucket, and the time history of the components of the pull rod force in each direction. The bucket tooth tip load time history in the entire motion process in the global coordinate system is determined based on the bucket tooth tip load time history in the local coordinate system, the bucket and ground angle time history, and the angle between the local coordinate system Y axis and the vertical direction at the zero time position; The bucket tooth tip load time history during the excavation process is extracted based on the bucket tooth tip load time history during the entire motion process in the global coordinate system; Determine the loading angle of the test actuator based on the bucket tooth tip load time history during the digging process; Determine the time history of the test actuator loading force based on the time history of the bucket tooth tip vertical load and the loading angle of the test actuator during the excavation process; Singular values were removed from the test data to obtain a series of load cycles with different amplitudes and means. The load amplitudes were divided into multiple unequal intervals and the acceleration spectrum of the structure was compiled using the relative equivalent damage principle. Based on the operating characteristics of the loader, a "low-high-low" loading sequence was used to simulate the actual operating load to obtain the test loading spectrum block. The loading wave was a sine wave. The obtained test actuator loading load spectrum is loaded onto the above-mentioned loader key component fatigue reliability test device through the actuator.

3. A loading method for fatigue reliability test of a key component for a loader according to claim 1, characterized in that: The actuator (3) comprises a hydraulic cylinder (3-1), an actuator fixing seat (3-3) and a bucket fixing seat (3-4); Both ends of the hydraulic oil cylinder (3-1) are respectively connected to the actuator fixing seat (3-3) and the bucket fixing seat (3-4) via spherical hinge joints (3-2), and the hydraulic oil cylinder (3-1) can rotate around the spherical hinge joint (3-2).

4. A loading method for fatigue reliability test of a key component for a loader according to claim 3, characterized in that: The actuator fixing seat (3-3) is installed on the rigid wall (2), and a plurality of through holes are formed on the actuator fixing seat (3-3).

5. A loading method for fatigue reliability test of a key component for a loader according to claim 4, characterized in that: A plurality of mounting holes (2-1) are provided on the rigid wall (2).

6. A loading method for fatigue reliability test of a key component for a loader according to claim 1, characterized in that: A triangular reinforcement plate (5-4) is installed between the rear frame connecting plate (5-1) and the rectangular connecting square steel (5-2).

7. A loading method for fatigue reliability test of a key component for a loader according to claim 1, characterized in that: It also includes a base (1), the base (1) is provided with a plurality of T-slots (1-1), and the rigid wall (2), the front frame support (4) and the rear frame support (5) are all movably mounted on the base (1) by means of bolts.

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