Fatigue test device for compression springs

Abstract

This invention discloses a fatigue testing device for compression springs, relating to the field of spring fatigue testing technology. The device includes a frame, an electrical cabinet and a compression mechanism housed within the frame, as well as alarms and a host computer mounted on the top and side walls of the frame. The compression mechanism mainly includes a servo lifting system, a mounting plate, a spring mounting tray, a spring pressure plate, a support frame, a servo compression system, and a protective cover. The servo lifting system is connected to the spring mounting tray and is used to lift it to the testing position; the servo compression system is connected to the spring pressure plate and drives it to reciprocate up and down to compress the spring; a laser displacement sensor mounted on the support frame is used to monitor the movement stroke of the spring pressure plate. This invention integrates automated control and precision sensing, aiming to automate the fatigue testing of helical compression springs, improving testing efficiency and operational safety.

Description

Technical Field

[0001] This invention relates to the field of spring fatigue testing technology, and in particular to a fatigue testing device for compression springs. Background Technology

[0002] As a key elastic component, helical compression springs are widely used in many industrial fields such as automobiles, machinery, aerospace, and precision instruments. Their fatigue life directly affects the reliability, safety, and service life of assembled equipment. Therefore, conducting scientific and accurate fatigue life testing is crucial in the design verification and production quality control stages of springs. Currently, fatigue testing technologies and equipment for helical compression springs have the following main limitations: 1. Low automation and low testing efficiency: Currently, many fatigue tests in the industry still rely on traditional testing machines operated manually. The testing process requires manual clamping of springs, manual setting or changing of loads, recording of data, and constant monitoring. This method is not only labor-intensive and costly, but also slow in pace, failing to meet the needs of large-volume, high-frequency testing, thus becoming a bottleneck in production capacity and quality control.

[0003] 2. Inconvenient and inflexible adjustment of test parameters: The adjustment range of key parameters such as load and stroke in some existing testing equipment or tooling is fixed or difficult to adjust. For example, to adapt to tests of springs of different specifications or under different load conditions, it is often necessary to change different indenters, bases, or adjust complex mechanical structures, a cumbersome and time-consuming process. This results in limited test conditions, making it difficult to efficiently simulate the various stress states of springs under actual working conditions, thus limiting the scope of testing and its engineering guidance value.

[0004] 3. Test accuracy and consistency are affected by human factors: Manual operation inevitably introduces clamping errors, reading errors, and misjudgments due to fatigue. At the same time, some existing equipment with low automation has limited frequency, accuracy, and stability of cyclic loading, making it difficult to guarantee strict consistency of each loading in long-term, large-batch testing, thus affecting the accuracy and comparability of test data.

[0005] 4. Limited versatility of testing equipment: Commercially available dedicated spring fatigue testing machines are often designed for specific size ranges or structures (such as equal-pitch cylindrical springs), and their clamping fixtures (clamps or trays) are usually of fixed dimensions. When dealing with helical compression springs with varying pitch diameters, wire diameters, or even different cross-sectional shapes (such as rectangular or flat) or special structures (such as conical), a large number of dedicated fixtures are required, increasing testing costs and management complexity, and making it impossible to quickly respond to the testing needs of multiple varieties and small batches.

[0006] 5. Lack of systematic data management and analysis support: Traditional testing methods focus on obtaining conclusive data on whether a spring is qualified, but lack effective automatic acquisition, storage, and analysis methods for the massive amounts of process data generated during testing (such as real-time load, displacement, and cycle count). This is not conducive to establishing a complete spring performance database and cannot provide strong support for data-driven life prediction, reliability assessment, and design backtracking optimization.

[0007] In summary, existing technologies for fatigue testing of helical compression springs generally suffer from low efficiency, insufficient flexibility, difficulty in ensuring accuracy and consistency, limited adaptability, and insufficient data value extraction. Therefore, the industry urgently needs an intelligent fatigue testing device that can achieve rapid, automated, high-precision, wide-range load adjustment, and adaptability to various spring specifications. This would improve testing efficiency, enrich testing conditions, ensure data quality, and enable in-depth data analysis and applications. Summary of the Invention

[0008] The purpose of this invention is to provide a fatigue testing device for compression springs. This device, by setting up an integrated structure including a servo lifting system, a servo compression system, a laser displacement sensor, and a central control unit, solves the problems of low efficiency and poor consistency in manual testing in the prior art, thereby realizing the automation and intelligence of the spring fatigue testing process and improving testing accuracy and efficiency.

[0009] The technical solution of the present invention to solve the above-mentioned technical problems is: a fatigue testing device for compression springs, including a frame, an electrical cabinet and a compression mechanism are provided inside the frame, an alarm is provided on the top of the frame, and a host computer for human-computer interaction is also provided on one outer wall of the frame; the electrical cabinet, the compression mechanism and the host computer are electrically connected. The compression mechanism includes, from bottom to top, a servo lifting system, a mounting plate, a spring mounting tray, a spring pressure plate, a support frame, and a servo compression system; the servo lifting system is mounted on the mounting plate and is detachably connected to the horizontally positioned spring mounting tray; the servo compression system is mounted on the top of the support frame and is connected to the spring pressure plate, which is horizontally positioned directly above the spring mounting tray; the servo compression system is covered with a protective cover, and the support frame is also equipped with a laser displacement sensor for detecting the movement stroke of the spring pressure plate.

[0010] As a further improvement of the present invention, the servo lifting system includes a servo electric cylinder with a vertically extending output end, the servo electric cylinder being fixedly mounted on the mounting plate, and the output end of the servo electric cylinder passing through the mounting plate and being connected to the lower surface of the lifting top plate horizontally positioned above the mounting plate; the edge of the lifting top plate is provided with an adjustable clamping mechanism for clamping and fixing the spring mounting tray. The mounting plate is vertically provided with multiple lifting guide linear bearings arranged around the output end of the servo electric cylinder. A lifting guide shaft is movably inserted into the lifting guide linear bearing, and the upper end of the lifting guide shaft is fixedly connected to the lower surface of the lifting top plate.

[0011] As a further improvement of the present invention, the adjustable clamping mechanism includes symmetrically arranged clamping blocks, and each clamping block is provided with a screw support on the side away from the center of the lifting top plate. A horizontally arranged T-shaped screw is threaded onto the screw support and one end is rotatably connected to the clamping block.

[0012] As a further improvement of the present invention, the spring mounting tray is provided with a plurality of adjustable mounting slots; a top block is provided at the bottom axis of each adjustable mounting slot, and a screw threaded to the bottom surface of the adjustable mounting slot is provided at the lower end of the top block; a plurality of wedge-shaped locking blocks are evenly distributed circumferentially on the bottom outer edge of the adjustable mounting slot, which can only move radially along the adjustable mounting slot, and the wedge-shaped locking blocks and the top blocks are in a vertical wedge fit; an elastic element is also provided between the wedge-shaped locking blocks and the side wall of the adjustable mounting slot.

[0013] As a further improvement of the present invention, the servo compression system includes a compression servo motor, a reducer, a drive shaft, an eccentric adjustment mechanism, a connecting rod, and a drive plate; the compression servo motor is connected to the reducer and is mounted on the top of the support frame via a reducer mounting base; the output end of the reducer is connected to one end of the drive shaft via a coupling; the drive shaft is mounted in a bearing mounting base via tapered roller bearings and is axially locked by a locking nut; the bearing mounting base is fixed to the top of the support frame. The eccentric adjustment mechanism is fixedly installed at the other end of the drive shaft; the upper end of the connecting rod is connected to the eccentric adjustment mechanism via a deep groove ball bearing; the lower end of the connecting rod passes through the support frame and is connected to the drive plate via a deep groove ball bearing, and is fixed by a pin; the spring pressure plate is fixed on the lower surface of the drive plate. The drive board is also provided with a compression guide assembly for circumferentially limiting it and allowing it to move only in a straight line in the vertical direction.

[0014] As a further improvement of the present invention, the compression guide assembly includes at least one vertically arranged compression guide shaft and a compression guide linear bearing that is slidably sleeved with the compression guide shaft; the compression guide linear bearing is fixed on the support frame, the lower end of the compression guide shaft is fixed on the drive plate, and the upper end of the compression guide shaft is fixedly sleeved with a stop ring to prevent it from falling out of the compression guide linear bearing.

[0015] As a further improvement of the present invention, the eccentric adjustment mechanism includes a mounting disk, a lead screw, a nut, a guide slider, and a rotating wheel; the mounting disk is coaxially fixed to the end of the transmission shaft; the lead screw is rotatably mounted on the mounting disk along the radial direction of the mounting disk, and one end of the lead screw is detachably connected to the output shaft of the self-aligning servo motor; the self-aligning servo motor is mounted on a bearing mounting seat through a self-aligning motor mounting bracket, and the self-aligning motor mounting bracket has a rectangular slot for adjusting the vertical position of the self-aligning servo motor; The nut is threadedly fitted to the lead screw; the guide slider is fixed to the nut and circumferentially limits the nut so that it can only move along the axial direction of the lead screw; the rotating wheel is fixedly mounted on the guide slider, and the adjustable distance between the center point of the rotating wheel and the rotation center point of the transmission shaft constitutes the eccentricity; the deep groove ball bearing at the upper end of the connecting rod is connected to the outer circumference of the rotating wheel; the mounting disc is also provided with a lead screw clamping block for locking the lead screw after adjusting the eccentricity.

[0016] As a further improvement of the present invention, the lead screw is rotatably mounted on the mounting disk via a first lead screw mounting seat and a second lead screw mounting seat.

[0017] As a further improvement of the present invention, a safety door with a magnetic door switch is installed on the frame, and the magnetic door switch is electrically connected to the alarm.

[0018] Beneficial effects Compared with the prior art, the advantages of the fatigue testing device for compression springs of the present invention are as follows: 1. Achieves a high degree of automation, significantly improving testing efficiency and reducing labor costs: This invention integrates a servo lifting system, a servo compression system, host computer control, and laser displacement sensor detection, realizing full automation of the entire process from spring clamping, automatic height positioning, cyclic compression testing to data acquisition. Operators only need to place the spring and set parameters; the device can automatically complete hundreds of thousands or even millions of fatigue tests without manual intervention. This not only greatly reduces labor intensity and manpower requirements but also increases the efficiency of a single test by several times or even tens of times by simultaneously testing multiple springs (multiple mounting slots on the spring mounting tray), effectively solving the bottleneck problems of slow testing pace and inability to meet the needs of large-scale testing in traditional methods. 2. Provides convenient and precise load adjustment capabilities, enriching test conditions: One of the core innovations of this invention lies in the eccentric adjustment mechanism in the servo compression system. By controlling the servo motor driving the lead screw and nut mechanism for centering, the eccentricity of the rotating wheel relative to the center of the transmission shaft can be adjusted steplessly and precisely. According to the crank-slider principle, the eccentricity directly determines the compression stroke of the spring pressure plate, and thus linearly controls the load applied to the spring according to Hooke's law. Compared with the traditional method of replacing the pressure head or mechanical parts, this adjustment method is simple to operate (can be controlled by a program), has a wide adjustment range, and high precision. It can quickly respond to the test requirements of different fatigue load conditions, efficiently simulate the diverse actual working conditions of the spring, and greatly enhance the flexibility of testing and its engineering application value. 3. Ensures high precision and consistency in the testing process: The device uses a high-precision servo motor as the drive source, combined with a reducer and linear bearing guide assembly, ensuring smooth, accurate, and high-speed loading motion (frequency up to tens of hertz). A laser displacement sensor monitors the actual travel of the spring platen in real time and compares it with the theoretical travel calculated based on the set load, forming a closed-loop control. If the error exceeds the limit, an automatic alarm is triggered and the machine stops, ensuring that each test is conducted under the preset precise load. This closed-loop control mechanism effectively eliminates errors caused by mechanical clearances, temperature drift, and other factors, ensuring high consistency of loading conditions in long-term, large-batch testing, thereby obtaining accurate, reliable, and comparable test data and avoiding errors caused by human factors. 4. Excellent versatility and adaptability: This invention solves the problem of poor versatility of testing devices through a dual design. First, the adjustable mounting slots on the spring mounting tray utilize the wedge-shaped fit between the top block and the wedge-shaped locking block. A single mounting slot can firmly support springs with different mean diameters and wire diameters within a certain diameter range. Furthermore, the circumferentially distributed design of the wedge-shaped locking blocks allows it to adapt well to various cross-sectional shapes such as round, rectangular, and flat springs, as well as conical helical springs. Second, the entire spring mounting tray adopts a modular design that allows for quick replacement. By changing to different series of tray sizes, the applicable range of test spring sizes can be expanded several times. This design enables a single device to meet the testing needs of "multiple varieties and small batches," significantly reducing the configuration cost and management complexity of dedicated fixtures. 5. It lays a solid foundation for intelligent data analysis and life prediction: Through a host computer and sensors, the device can automatically and completely record the spring's test parameters (such as set load, actual stroke, number of cycles, test status, etc.) and all process data. This massive amount of high-quality test data can be systematically stored and used to build a performance database for helical compression springs. Based on this database, in-depth statistical analysis can be performed, and more accurate fatigue life models can be established, thereby enabling more scientific life assessment and failure prediction for springs used in critical parts, achieving predictive maintenance. This transcends the limitations of traditional testing, which is only used for pass / fail determination, fully exploring the potential value of test data and providing strong data support for product design optimization and quality control.

[0019] The invention will become clearer from the following description, taken in conjunction with the accompanying drawings, which are used to explain embodiments of the invention. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a perspective view of the present invention; Figure 2 This is an exploded view of the compression mechanism of the present invention; Figure 3 This is an exploded view of the servo lifting system of the present invention; Figure 4 This is a schematic diagram of the structure of the spring mounting tray of the present invention; Figure 5 This is an exploded view of the servo compression system of the present invention; Figure 6 This is an exploded view of the eccentric adjustment mechanism of the present invention.

[0022] Wherein: 1000-Frame; 2000-Electrical cabinet; 3000-Host computer; 4000-Compression mechanism; 4100-Servo lifting system; 4101-Servo electric cylinder; 4102-Lifting guide shaft; 4103-Lifting guide linear bearing; 4104-Lifting top plate; 4105-Clamping block; 4106-Screw support; 4107-T-shaped screw; 4200-Servo compression system; 4201-Drive board; 4202-Pin; 4203-Deep groove ball bearing; 4204-Connecting rod; 4205-Compression guide shaft; 4206-Compression guide linear bearing; 4207-Stop ring; 4208-Eccentric adjustment mechanism; 4208a-Mounting disc; 4208b-First screw mounting seat; 4208c-Second screw mounting seat; 420 8d - Rotating wheel; 4208e - Guide slider; 4208f - Nut; 4208g - Lead screw; 4208h - Lead screw clamping block; 4209 - Drive shaft; 4210 - Tapered roller bearing; 4211 - Locking nut; 4212 - Self-aligning servo motor; 4213 - Self-aligning motor mounting bracket; 4214 - Bearing mounting base; 4215 - Coupling; 4216 - Reducer mounting base; 4217 - Reducer; 4218 - Compression servo motor; 4300 - Support frame; 4400 - Spring mounting tray; 4401 - Top block; 4402 - Elastic element; 4403 - Wedge-shaped clamping block; 4500 - Spring pressure plate; 4600 - Laser displacement sensor; 4700 - Mounting plate; 4800 - Protective cover; 5000 - Alarm. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0024] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; of course, they can also refer to a mechanical connection or an electrical connection; furthermore, they can refer to a direct connection, an indirect connection through an intermediate medium, or a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0025] Embodiments of the present invention will now be described with reference to the accompanying drawings.

[0026] Example: Specific embodiments of the present invention are as follows: Figure 1 As shown, a fatigue testing device for compression springs has a clear overall structure and well-defined functional modules. The device mainly includes a frame 1000, an electrical cabinet 2000, a host computer 3000, a compression mechanism 4000, and an alarm 5000.

[0027] The frame 1000 serves as the main support and protection structure for the entire device, housing the electrical cabinet 2000 and the compression mechanism 4000. The electrical cabinet 2000 integrates electrical control components such as a PLC, servo driver, and switching power supply, providing power distribution and control logic for the entire testing system. The host computer 3000 is mounted on one outer wall of the frame 1000, serving as the human-machine interface for setting test parameters such as load and cycle count; starting / stopping the test; real-time display of test status, such as the current cycle count and actual travel; and generating and exporting test reports. The electrical cabinet 2000, compression mechanism 4000, and host computer 3000 are electrically connected via cables, forming a complete measurement and control system. The frame 1000 is equipped with a safety door with a transparent observation window. The safety door has a magnetic switch, which is electrically connected to an alarm 5000 on the top of the frame. If the safety door is accidentally opened during testing, the magnetic switch is triggered, and the alarm 5000 immediately emits an audible and visual alarm signal to ensure operational safety.

[0028] like Figure 2 As shown, the compression mechanism 4000 is the core functional unit for performing fatigue testing. Its structure, from top to bottom, mainly includes a servo compression system 4200, a support frame 4300, a spring pressure plate 4500, a spring mounting tray 4400, a mounting plate 4700, and a servo lifting system 4100. The servo lifting system 4100 is mounted on the mounting plate 4700 and is detachably connected to the horizontally positioned spring mounting tray 4400. The support frame 4300 is fixed to the mounting plate 4700, providing support for the upper structure. The servo compression system 4200 is mounted on top of the support frame 4300 and is connected to the spring pressure plate 4500, which is horizontally positioned directly above the spring mounting tray 4400. The servo compression system 4200 is covered with a protective cover 4800 to prevent exposed moving parts and improve safety. The support frame 4300 is also equipped with a laser displacement sensor 4600 for detecting the movement stroke of the spring pressure plate 4500.

[0029] In this embodiment, the specific structure and working principle of the servo lifting system 4100 are as follows: like Figure 3As shown, the servo lifting system 4100 mainly includes a servo electric cylinder 4101, a lifting guide shaft 4102, a lifting guide linear bearing 4103, and a lifting top plate 4104. The servo electric cylinder 4101 is vertically fixedly installed below the mounting plate 4700, and its vertically positioned output end passes through a through hole on the mounting plate 4700 and is connected to the lower surface of the lifting top plate 4104, which is horizontally positioned above the mounting plate 4700. To ensure that the lifting top plate 4104 moves smoothly in the vertical direction and prevents swaying or jamming due to lateral forces, multiple lifting guide linear bearings 4103 are vertically arranged around the output end of the servo electric cylinder 4101 on the mounting plate 4700. A lifting guide shaft 4102 is movably inserted into each lifting guide linear bearing 4103, and the upper end of the lifting guide shaft 4102 is fixedly connected to the lower surface of the lifting top plate 4104. In this way, the servo electric cylinder 4101 provides driving force, while the cooperation between the lifting guide shaft 4102 and the linear bearing provides precise circumferential limiting and guiding, ensuring the rigidity and straightness of the lifting motion.

[0030] The upper surface of the lifting top plate 4104 is used to support the spring-mounted tray 4400. To accommodate trays of different sizes and achieve quick clamping, an adjustable clamping mechanism is provided at the edge of the lifting top plate 4104. This mechanism includes at least two symmetrically arranged clamping blocks 4105. Each clamping block 4105 has a lead screw support 4106 fixed on its side away from the center of the lifting top plate 4104. A horizontally positioned T-shaped lead screw 4107 passes through a threaded hole in the lead screw support 4106, and its end is rotatably connected to the clamping block 4105 via a bearing. When the tray needs to be fixed, the operator rotates the T-shaped lead screw 4107, which drives the clamping block 4105 to move radially inward, thereby clamping the spring-mounted tray 4400 placed on the lifting top plate 4104. By adjusting the moving distance of the clamping blocks 4105 on both sides, the installation of various tray sizes can be flexibly accommodated.

[0031] In this embodiment, the general design principle of the spring mounting tray 4400 is as follows: like Figure 4As shown, to enable batch testing and broad adaptability to different spring specifications, the spring mounting tray 4400 is machined with multiple "adjustable mounting slots" arranged in a matrix. The core of each adjustable mounting slot is an adaptive clamping mechanism. At the central axis of the bottom of the adjustable mounting slot, a top block 4401 is provided, and the lower end of the top block 4401 is equipped with a screw that engages with the threaded bottom surface of the adjustable mounting slot, allowing the top block 4401 to move up and down relative to the spring mounting tray 4400 when rotated. On the outer edge of the bottom surface of the adjustable mounting slot, three wedge-shaped locking blocks 4403 are evenly distributed circumferentially. These wedge-shaped locking blocks 4403 are designed to slide only radially along the adjustable mounting slot. The inner inclined surface of the wedge-shaped locking blocks 4403 forms a "vertical wedge fit" with the conical or inclined surface of the top block 4401. An elastic element 4402 is also installed between the wedge-shaped locking blocks 4403 and the sidewall of the mounting slot.

[0032] In use, place the helical compression spring to be tested into the adjustable mounting slot, ensuring its bottom ring fits onto the three wedge-shaped blocks 4403. Then, use a tool to rotate the top block 4401, causing it to move upwards. The conical surface of the top block 4401 pushes upwards against the inclined surface of the wedge-shaped blocks 4403, forcing the three wedge-shaped blocks 4403 to move radially outwards synchronously until they tightly support the inner ring of the spring. The elastic element 4402 is compressed, and its rebound force provides a radially inward constraint force to the wedge-shaped blocks, forming a stable self-locking state and preventing loosening during testing. Because the three wedge-shaped blocks 4403 are circumferentially distributed and move radially independently, they can automatically adapt to different cross-sectional shapes, such as circular, rectangular, and flat springs, and can well support the variable diameter bottom ring of conical springs. By changing the spring mounting trays 4400 with different inner diameter ranges, the upper and lower limits of the size of the springs that the device can test can be further expanded.

[0033] In this embodiment, regarding the servo compression system 4200 and its core eccentric adjustment mechanism 4208: like Figure 5 As shown, the servo compression system 4200 is a precision loading system that converts rotary motion into linear reciprocating motion based on the crank-slider mechanism principle. It mainly includes a servo motor 4218 for compression, a reducer 4217, a drive shaft 4209, an eccentric adjustment mechanism 4208, a connecting rod 4204, and a drive plate 4201. Specifically: A servo motor 4218 for compression is directly connected to a reducer 4217 and is fixed to the top of a support frame 4300 via a reducer mounting base 4216. The output shaft of the reducer 4217 is connected to one end of a horizontal drive shaft 4209 via a coupling 4215. The drive shaft 4209 is supported within a bearing mounting base 4214 by a pair of tapered roller bearings 4210, which is fixed to the support frame 4300. A locking nut 4211 is locked onto the drive shaft 4209 to secure the inner ring of the tapered roller bearings 4210 and prevent axial movement.

[0034] An eccentric adjustment mechanism 4208 is fixedly mounted on the free end of the drive shaft 4209. The upper end of the connecting rod 4204 is connected to the outer periphery of the rotating wheel 4208d in the eccentric adjustment mechanism 4208 via a deep groove ball bearing 4203. The lower end of the connecting rod 4204 passes through a through hole in the middle of the support frame 4300 and is connected to the drive plate 4201 via another deep groove ball bearing 4203, and is fixed with a pin 4202 to ensure a reliable connection. The spring pressure plate 4500 is fixed to the lower surface of the drive plate 4201 by bolts.

[0035] To ensure that the drive plate 4201 and the spring pressure plate 4500 move strictly in a vertical linear motion and do not swing with the connecting rod 4204, the device is equipped with a compression guide assembly. This assembly includes two vertically arranged compression guide shafts 4205 and compression guide linear bearings 4206 that are slidably fitted with them. The compression guide linear bearings 4206 are fixedly mounted on the support frame 4300. The lower end of the compression guide shaft 4205 is fixedly connected to the drive plate 4201, and the upper end is equipped with a stop ring 4207 to prevent the shaft from dislodging from the bearing.

[0036] In this embodiment, the precision adjustment principle of the eccentric adjustment mechanism 4208 is as follows: like Figure 6 As shown, the eccentric adjustment mechanism 4208 is the core component for achieving stepless and precise load adjustment. It includes a mounting disk 4208a coaxially fixed to the end of the drive shaft 4209. A lead screw 4208g, arranged radially along the mounting disk 4208a, is mounted on it via a first lead screw mounting seat 4208b and a second lead screw mounting seat 4208c. One end of the lead screw 4208g can be detachably connected to the output shaft of the self-aligning servo motor 4212 via a clutch or a simple hole-shaft engagement. The self-aligning servo motor 4212 is mounted on the side of the bearing mounting seat 4214 via a self-aligning motor mounting bracket 4213, which has a long rectangular slot allowing for fine-tuning of the vertical position of the self-aligning servo motor 4212, facilitating engagement and disengagement with the lead screw 4208g. A nut 4208f is threaded into the lead screw 4208g. A guide slider 4208e is fixed to the nut 4208f. The guide slider 4208e engages with a radial groove on the mounting disc 4208a, restricting the nut 4208f and the guide slider 4208e to move only along the axial direction of the lead screw 4208g—that is, radially along the mounting disc 4208a—and preventing rotation. A rotating wheel 4208d is fixedly mounted on the guide slider 4208e. The mounting disc 4208a is also provided with a lead screw clamping block 4208h for locking the lead screw 4208g after adjusting the eccentricity.

[0037] When the test load needs to be changed, according to Hooke's Law F=KX, the required compression stroke X is calculated from the target load F and the spring stiffness K. Then, according to the crank-slider kinematic formula, the required crank radius, i.e., the eccentricity e—the distance from the center P of the rotating wheel 4208d to the rotation center O of the drive shaft 4209—is calculated from the stroke X. The host computer 3000 sends the eccentricity e adjustment command to the controller, which drives the self-aligning servo motor 4212 to rotate by a specific angle, causing the lead screw 4208g to rotate. Since the nut 4208f is circumferentially limited, it drives the guide slider 4208e and the rotating wheel 4208d to move radially linearly, precisely adjusting to the position of the target eccentricity e. After adjustment, the output shaft of the self-aligning servo motor 4212 is raised to disengage it from the lead screw 4208g. Then, the lead screw clamping block 4208h mounted on the mounting disc is manually locked to lock the lead screw 4208g in place, preventing displacement due to vibration during subsequent high-speed operation and ensuring that the eccentricity remains constant during testing. This design achieves digital and programmed precise adjustment of the load, with a wide adjustment range.

[0038] In this embodiment, the working process and closed-loop control principle of the device are as follows: S1. Preparation stage: The servo electric cylinder 4101 of the servo lifting system 4100 is in the zero position, i.e., the lowest point. The spring mounting tray 4400, which contains multiple springs to be tested, is placed on the lifting top plate 4104 and clamped with an adjustable clamping mechanism.

[0039] S2. Parameter Setting and Automatic Adjustment: The load F, number of cycles N, and other parameters for this test are set via the host computer 3000. The system automatically calculates and executes the aforementioned adjustment process for the eccentricity e. Simultaneously, the system calculates the required lifting height H of the servo electric cylinder 4101 according to the formula H = H0 + e - L0. Here, H0 is the design inherent value, and L0 is the free length of the spring.

[0040] S3. Automatic Alignment and Pre-tensioning: The servo cylinder 4101 actuates, raising the spring mounting tray 4400 to a height H. At this point, the upper surface of the spring is in slight contact with the lower surface of the spring pressure plate 4500 or reaches the preset initial contact state. Subsequently, the lifting servo motor enters the position holding state, providing a robust rigid support platform for the entire testing system.

[0041] S4. Test Execution and Closed-Loop Verification: Start the compression servo motor 4218. The motor drives the spring pressure plate 4500 to reciprocate linearly via a crank-slider mechanism, cyclically compressing the spring. During the first revolution of the motor, the laser displacement sensor 4600, mounted on the support frame 4300, detects the position of the lower surface of the spring pressure plate 4500 in real time, recording the displacement values ​​of its highest and lowest points. The difference between the two values ​​is the measured compression stroke X_actual. Wherein: Closed-loop control principle: The control system compares the measured stroke X_actual with the theoretically calculated stroke X. If the error is within the allowable tolerance range (e.g., ±0.01mm), the load setting is determined to be accurate, and the compression servo motor 4218 continues to run until the set number of cycles N is completed, after which it automatically stops.

[0042] If the error exceeds the tolerance, the system immediately stops the compression servo motor 4218 and triggers alarm 5000, prompting the operator to check the load settings or mechanism status. This closed-loop verification mechanism fundamentally ensures that the load applied in each test precisely matches the preset value, guaranteeing the consistency and reliability of the test data.

[0043] Test completion: After the test, the servo cylinder 4101 retracts to the zero position, and the spring mounting tray 4400 descends to the low position, facilitating the operator to remove the tested spring and install a new one. All test parameters, actual stroke data, number of cycles, timestamps, and other information are automatically recorded and stored in the database of the host computer 3000.

[0044] In summary, this device has the following advantages: The fully automated coordination of the servo lifting and compression systems enables "one-click" testing, significantly improving efficiency and reducing labor costs.

[0045] The stepless precision adjustment mechanism for eccentricity based on a servo motor and a lead screw nut enables convenient, accurate, and wide-range adjustment of the load, greatly enriching the testing conditions.

[0046] The laser displacement sensor 4600 and the closed-loop feedback of motion control enable real-time monitoring and calibration of the loading stroke, ensuring high precision and consistency in the testing process.

[0047] The adjustable mounting slots and modular quick-change design of the Spring Mounting Tray 4400 enable a single unit to securely support springs of various sizes, shapes, and structures, providing exceptional versatility and adaptability.

[0048] The integrated host computer 3000 data management system automatically collects and stores test data throughout the entire process, laying a solid foundation for building a spring performance database and performing life prediction and intelligent analysis.

[0049] The present invention has been described above in conjunction with the preferred embodiments, but the present invention is not limited to the embodiments disclosed above, but should cover various modifications and equivalent combinations made in accordance with the essence of the present invention.

Claims

1. A fatigue testing device for compression springs, characterized in that, The device includes a rack (1000), which houses an electrical cabinet (2000) and a compression mechanism (4000). An alarm (5000) is installed on the top of the rack (1000), and a host computer (3000) for human-computer interaction is installed on one outer wall of the rack (1000). The electrical cabinet (2000), the compression mechanism (4000), and the host computer (3000) are electrically connected. The compression mechanism (4000) includes, from bottom to top, a servo lifting system (4100), a mounting plate (4700), a spring mounting tray (4400), a spring pressure plate (4500), a support frame (4300), and a servo compression system (4200); the servo lifting system (4100) is mounted on the mounting plate (4700) and is detachably connected to the horizontally positioned spring mounting tray (4400); the servo compression system (4200) is mounted on the top of the support frame (4300) and is connected to the spring pressure plate (4500) which is horizontally positioned directly above the spring mounting tray (4400); the servo compression system (4200) is covered with a protective cover (4800), and the support frame (4300) is also equipped with a laser displacement sensor (4600) for detecting the movement stroke of the spring pressure plate (4500).

2. The fatigue testing apparatus for compression springs according to claim 1, characterized in that, The servo lifting system (4100) includes a servo electric cylinder (4101) with a vertically telescopic output end. The servo electric cylinder (4101) is fixedly mounted on the mounting plate (4700), and the output end of the servo electric cylinder (4101) passes through the mounting plate (4700) and is connected to the lower surface of the lifting top plate (4104) which is horizontally set above the mounting plate (4700). The edge of the lifting top plate (4104) is provided with an adjustable clamping mechanism for clamping and fixing the spring mounting tray (4400). The mounting plate (4700) is vertically provided with multiple lifting guide linear bearings (4103) arranged around the output end of the servo electric cylinder (4101). A lifting guide shaft (4102) is movably inserted into the lifting guide linear bearing (4103), and the upper end of the lifting guide shaft (4102) is fixedly connected to the lower surface of the lifting top plate (4104).

3. The fatigue testing apparatus for compression springs according to claim 2, characterized in that, The adjustable clamping mechanism includes symmetrically arranged clamping blocks (4105). Each clamping block (4105) is provided with a screw support (4106) on the side away from the center of the lifting top plate (4104). A T-shaped screw (4107) is threaded on the screw support (4106) and is horizontally arranged and rotatably connected to the clamping block (4105) at one end.

4. The fatigue testing apparatus for compression springs according to any one of claims 1-3, characterized in that, The spring mounting tray (4400) is provided with multiple adjustable mounting slots; each adjustable mounting slot has a top block (4401) at its bottom axis, and the bottom end of the top block (4401) is provided with a screw threaded to the bottom surface of the adjustable mounting slot; multiple wedge-shaped blocks (4403) that can only move radially along the adjustable mounting slot are evenly distributed on the bottom outer edge of the adjustable mounting slot, and the wedge-shaped blocks (4403) and the top block (4401) are in a vertical wedge fit, and an elastic element (4402) is also provided between the wedge-shaped blocks (4403) and the side wall of the adjustable mounting slot.

5. The fatigue testing apparatus for compression springs according to claim 1, characterized in that, The servo compression system (4200) includes a compression servo motor (4218), a reducer (4217), a drive shaft (4209), an eccentric adjustment mechanism (4208), a connecting rod (4204), and a drive plate (4201). The compression servo motor (4218) is connected to the reducer (4217) and is mounted on the top of the support frame (4300) via a reducer mounting base (4216). The output end of the reducer (4217) is connected to one end of the drive shaft (4209) via a coupling (4215). The drive shaft (4209) is mounted in a bearing mounting base (4214) via a tapered roller bearing (4210) and is axially locked by a locking nut (4211). The bearing mounting base (4214) is fixed to the top of the support frame (4300). The eccentric adjustment mechanism (4208) is fixedly installed at the other end of the transmission shaft (4209); the upper end of the connecting rod (4204) is connected to the eccentric adjustment mechanism (4208) via a deep groove ball bearing (4203); the lower end of the connecting rod (4204) passes through the support frame (4300) and is connected to the drive plate (4201) via a deep groove ball bearing (4203), and is fixed by a pin (4202); the spring pressure plate (4500) is fixed on the lower surface of the drive plate (4201); The drive plate (4201) is also provided with a compression guide assembly for circumferentially limiting it and allowing it to move only in a straight line in the vertical direction.

6. The fatigue testing apparatus for compression springs according to claim 5, characterized in that, The compression guide assembly includes at least one vertically arranged compression guide shaft (4205) and a compression guide linear bearing (4206) that is slidably sleeved with the compression guide shaft (4205); the compression guide linear bearing (4206) is fixed on the support frame (4300), the lower end of the compression guide shaft (4205) is fixed on the drive plate (4201), and the upper end of the compression guide shaft (4205) is fixedly sleeved with a stop ring (4207) to prevent it from coming out of the compression guide linear bearing (4206).

7. The fatigue testing apparatus for compression springs according to claim 5 or 6, characterized in that, The eccentric adjustment mechanism (4208) includes a mounting disc (4208a), a lead screw (4208g), a nut (4208f), a guide slider (4208e), and a rotating wheel (4208d); the mounting disc (4208a) is coaxially fixed to the end of the transmission shaft (4209); the lead screw (4208g) is rotatably mounted on the mounting disc (4208a) along the radial direction of the mounting disc (4208a), and one end of the lead screw (4208g) is detachably connected to the output shaft of the self-aligning servo motor (4212); the self-aligning servo motor (4212) is mounted on the bearing mounting seat (4214) through a self-aligning motor mounting bracket (4213), and the self-aligning motor mounting bracket (4213) has a rectangular slot for adjusting the vertical position of the self-aligning servo motor (4212); The nut (4208f) is threadedly engaged with the lead screw (4208g); the guide slider (4208e) is fixed on the nut (4208f) and circumferentially limits the nut (4208f) so that it can only move axially along the lead screw (4208g); the rotating wheel (4208d) is fixedly mounted on the guide slider (4208e), and the adjustable distance between the center point of the rotating wheel (4208d) and the rotation center point of the transmission shaft (4209) constitutes the eccentricity; the deep groove ball bearing (4203) at the upper end of the connecting rod (4204) is connected to the outer circumference of the rotating wheel (4208d); the mounting disc (4208a) is also provided with a lead screw clamping block (4208h) for locking the lead screw (4208g) after adjusting the eccentricity.

8. The fatigue testing apparatus for compression springs according to claim 7, characterized in that, The lead screw (4208g) is rotatably mounted on the mounting disc (4208a) via the first lead screw mounting base (4208b) and the second lead screw mounting base (4208c).

9. The fatigue testing apparatus for compression springs according to claim 1, characterized in that, A safety door with a magnetic door switch is installed on the frame (1000), and the magnetic door switch is electrically connected to the alarm (5000).

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