An adaptive spindle unit load testing device and method

Abstract

This application proposes an adaptive spindle unit load testing device and method. The device includes: a simulated tool connected to a machine tool spindle; a simulated specimen placed on the device's worktable, with elastic elements disposed on the surface of the specimen; a multi-dimensional force sensor disposed at the load path nodes of the spindle unit; a displacement sensor disposed at the front end of the machine tool spindle; and a control unit connected to the multi-dimensional force sensor and the displacement sensor. The technical solution proposed in this application, during spindle unit load testing, directly measures the actual force at the load path nodes through the multi-dimensional force sensor, eliminating the need for indirect calculation based on offline calibration of the elastic elements and thus eliminating calibration errors. The control unit synchronously collects force and displacement signals, offsetting the influence of elastic element characteristic changes on control accuracy, and provides real-time feedback of test data. Simultaneously, it integrates high-precision constant force loading and dynamic load simulation on the same platform, improving the constant force control accuracy of the testing device.

Description

Technical Field

[0001] This application relates to the field of mechanical testing technology, and in particular to an adaptive spindle unit load testing device and method. Background Technology

[0002] As a core functional component of CNC machine tools, the spindle unit's load capacity and reliability testing are crucial for ensuring machine tool performance. Related technologies for spindle unit testing mainly fall into two categories: non-contact (such as air flotation and electromagnetic loading) and contact methods. While non-contact methods avoid additional influences, they generally suffer from system complexity, high cost, and insufficient accuracy in load force control. In the more widely used contact loading scheme, related technologies simulate the extrusion of an elastic element by a cutting tool and indirectly calculate the load based on the deformation of the pad, aiming to simulate multi-dimensional forces. However, this technology relies on pre-calibrated offline relationships of the elastic element's force-deformation relationship. These pre-calibrated relationships drift with fatigue of the elastic element material and temperature changes (from environmental heat transfer and frictional heat generation at the interface), resulting in inconsistent load force control, lack of real-time feedback, and poor test repeatability. Therefore, there is an urgent need for a testing device and method that can control the load force to be consistent with reality and provide real-time feedback. Summary of the Invention

[0003] This application provides an adaptive spindle unit load testing device and method to at least solve the technical problems of inability to provide real-time feedback of measurement data and low load control accuracy in machine tool load measurement.

[0004] A first aspect of this application provides an adaptive spindle unit load testing device, the device comprising:

[0005] Simulated cutting tool, connected to the machine tool spindle; A simulated specimen is placed on the worktable of the device, and an elastic element is provided on the surface of the simulated specimen. A multi-dimensional force sensor is installed at the load path node of the main spindle unit; A displacement sensor is installed at the front end of the machine tool spindle; The control unit is connected to the multi-dimensional force sensor and the displacement sensor.

[0006] Preferably, the device further includes: A servo drive unit, which is connected to the control unit and the simulated tool.

[0007] Preferably, the multidimensional force sensor is disposed between the simulated tool and the spindle.

[0008] A second aspect of this application provides an adaptive spindle unit load testing method, wherein the testing method employs the spindle unit load testing device according to any one of the preceding first aspects, and the testing method includes: Apply a load to the simulated tool; The initial force change value measured by the multi-dimensional force sensor and the initial displacement change value measured by the displacement sensor are obtained, and the initial stiffness value is determined based on the initial force change value and the initial displacement change value. The current force change value measured by the multi-dimensional force sensor and the current displacement change value measured by the displacement sensor are obtained, and the current stiffness value is determined based on the current force change value and the current displacement change value. Based on the current force change value, current displacement change value, initial stiffness value, and current stiffness value, the target displacement amount that the simulated tool needs to be adjusted is determined.

[0009] Preferably, the step of acquiring the initial force change value detected by the multi-dimensional force sensor and the initial displacement change value detected by the displacement sensor, and determining the initial stiffness value based on the initial force change value and the initial displacement change value, includes: The servo drive unit drives the simulated cutting tool to contact the elastic element on the surface of the simulated specimen, thereby loading the simulated specimen. A multi-dimensional force sensor monitors the force exerted by the simulated cutting tool on the simulated specimen during loading, and a displacement sensor monitors the displacement of the simulated cutting tool during loading. When the force measurement value of the multi-dimensional force sensor reaches a first force value, the corresponding displacement measurement value of the displacement sensor is a first displacement value; when the displacement measurement value of the displacement sensor reaches a second displacement value, the corresponding force measurement value of the multi-dimensional force sensor is a second force value. The first force value and the second displacement value are preset values. The difference between the first force value and the second force value is taken as the initial force change value, and the difference between the first displacement value and the second displacement value is taken as the initial displacement change value; The ratio of the initial force change value to the initial displacement change value is used as the initial stiffness value.

[0010] Preferably, the step of acquiring the current force change value measured by the multi-dimensional force sensor and the current displacement change value measured by the displacement sensor, and determining the current stiffness value based on the current force change value and the current displacement change value, includes: The servo drive unit drives the simulated tool to contact the elastic element on the surface of the simulated specimen, and the multi-dimensional force sensor monitors the force exerted by the simulated tool on the simulated specimen during the loading process. The displacement sensor monitors the displacement of the simulated tool during the loading process. When the force measurement value of the multi-dimensional force sensor reaches the first force value, the displacement measurement value of the displacement sensor is the first displacement value. Obtain the current force value measured by the multi-dimensional force sensor and the current displacement value measured by the displacement sensor; The difference between the first force value and the current force value is taken as the current force change value, and the difference between the first displacement value and the current displacement value is taken as the current displacement change value; The ratio of the current force change value to the current displacement change value is used as the current stiffness value.

[0011] Preferably, determining the target displacement that the simulated tool needs to be adjusted based on the current force change value, the current displacement change value, the initial stiffness value, and the current stiffness value includes: Based on the current force change value and the current stiffness value, determine the displacement ratio term error value; Based on the internal force changes and the current stiffness value in each time period, determine the cumulative displacement error. Based on the current force change value and the initial stiffness value, determine the displacement feedforward error value; The target displacement that the simulated tool needs to be adjusted is determined based on the displacement ratio error value, the cumulative displacement error, and the displacement feedforward error value.

[0012] Preferably, the method further includes: Based on the target displacement, a displacement compensation command is generated; The displacement compensation command is sent to the servo drive unit, which controls the simulated tool to achieve the target displacement based on the displacement compensation command.

[0013] Preferably, determining the current stiffness value and updating the current stiffness value in real time includes: The control unit generates test result data, which includes: force change data, stiffness change data, and spindle static stiffness data during the loading process.

[0014] Preferably, the method further includes: When the preset test termination conditions are met, the control unit issues a retraction command to terminate the loading. The test termination conditions include: the test runtime reaches a preset time threshold.

[0015] The technical solutions provided by the embodiments of this application bring at least the following beneficial effects: This application proposes an adaptive spindle unit load testing device and method. The device includes: a simulated tool connected to a machine tool spindle; a simulated specimen placed on the worktable of the device, the surface of which is provided with an elastic element; a multi-dimensional force sensor located at the load path node of the spindle unit; a displacement sensor located at the front end of the machine tool spindle; and a control unit connected to the multi-dimensional force sensor and the displacement sensor. The technical solution proposed in this application directly measures the actual force at the load path node using the multi-dimensional force sensor, eliminating the need for indirect calculation based on offline calibration of the elastic element and thus eliminating calibration errors. The control unit synchronously collects force and displacement signals, offsetting the influence of changes in the elastic element characteristics on control accuracy, and provides real-time feedback of test data. Simultaneously, it integrates high-precision constant force loading and dynamic load simulation on the same platform, improving the constant force control accuracy of the testing device.

[0016] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0017] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein: Figure 1 This is a structural diagram of an adaptive spindle unit load testing device according to an embodiment of this application; Figure 2 This is a flowchart of an adaptive spindle unit load testing method according to an embodiment of this application.

[0018] Figure label: 1-Simulated cutting tool; 2-Simulated specimen; 3-Elastic component; 4-Multidimensional force sensor; 5-Worktable. Detailed Implementation

[0019] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0020] In the field of CNC machine tools, the spindle unit is the core component that directly participates in cutting motion. Its dynamic performance and stiffness characteristics directly affect machining accuracy, surface quality, and tool life. To evaluate the spindle's load-bearing capacity under actual working conditions, spindle unit load testing is usually required. Traditional testing methods mainly include static stiffness testing and constant load loading testing. Static stiffness testing generally uses hydraulic or mechanical force application devices to apply unidirectional or multidirectional static forces to the end of the spindle, and calculates the static stiffness by measuring the relationship between force and displacement. This method cannot reflect the impact of dynamic load changes during machining on spindle performance. Constant load loading testing applies a load in a fixed direction while the spindle is rotating or not rotating, and records the deformation, but it is difficult to simulate the instantaneous fluctuations and directional changes of the load during actual cutting.

[0021] The testing systems in related technologies employ a combination of simulated specimens and force sensors. A simulated cutting tool is mounted on the spindle end, and a specimen fixed to the worktable is loaded. These tests typically rely on offline-calibrated elastic elements (such as springs or elastic components) to simulate the contact stiffness of the workpiece material. The force value is often indirectly calculated through the deformation of the elastic element, leading to the accumulation of calibration errors. Furthermore, traditional testing systems are mostly open-loop control, executing according to a preset loading path, lacking real-time closed-loop adjustment capabilities for force values. When the surface characteristics of the specimen change or the spindle experiences thermal deformation, the actual load deviates from the target value, affecting the repeatability and accuracy of the test results. As CNC machine tools develop towards higher precision and efficiency, higher demands are placed on the dynamic load simulation and adaptive control capabilities of the spindle unit under actual cutting conditions. Therefore, testing devices and methods that can control the loading force to be consistent with the actual force and provide real-time feedback are needed to more realistically reproduce force changes during machining and provide a reliable basis for machine tool performance evaluation and optimization.

[0022] This application proposes an adaptive spindle unit load testing device and method. The device includes: a simulated tool 1 connected to a machine tool spindle; a simulated specimen 2 placed on the worktable 5 of the device, with an elastic element 3 disposed on the surface of the simulated specimen 2; a multi-dimensional force sensor 4 disposed at the load path node of the spindle unit; a displacement sensor disposed at the front end of the machine tool spindle; and a control unit connected to the multi-dimensional force sensor 4 and the displacement sensor. The technical solution proposed in this application directly measures the actual force at the load path node through the multi-dimensional force sensor 4, eliminating the need for offline calibration and indirect calculation based on the elastic element 3, thus eliminating calibration errors. The control unit synchronously collects force and displacement signals, offsetting the influence of changes in the characteristics of the elastic element 3 on control accuracy, and providing real-time feedback of test data. Simultaneously, it integrates high-precision constant force loading and dynamic load simulation on the same platform, improving the constant force control accuracy of the testing device.

[0023] An adaptive spindle unit load testing device and method according to an embodiment of this application is described below with reference to the accompanying drawings.

[0024] Example 1 Figure 1 This is a structural diagram of an adaptive spindle unit load testing device according to an embodiment of this application, as shown below. Figure 1 As shown, the device includes: Simulated tool 1 is connected to the machine tool spindle; The simulated specimen 2 is placed on the workbench 5 of the device, and the surface of the simulated specimen 2 is provided with an elastic element 3; Multi-dimensional force sensor 4 is installed at the load path node of the main spindle unit; A displacement sensor is installed at the front end of the machine tool spindle; The control unit is connected to the multi-dimensional force sensor 4 and the displacement sensor.

[0025] The simulated tool 1, as the execution component of the test platform, can be fixedly installed on the end of the machine tool spindle, with its front end facing the simulated specimen 2 covered with an elastic pad. During the test, the spindle drives the simulated tool 1 to feed axially, applying a controllable compressive load to the simulated specimen 2, thereby simulating the mechanical action process when the tool and the workpiece come into contact during actual machining.

[0026] When simulating workpiece material, a simulated specimen 2 can be selected. The simulated specimen 2 is a component in the test platform used to bear the load. It can be installed on the machine tool's worktable 5, with its position opposite to the simulated tool 1. An elastic element 3 (such as an elastic pad) can be covered or set on the surface of the simulated specimen 2. The elastic element 3 can directly contact the simulated tool 1 and generate controllable elastic deformation during loading. This simulates the contact stiffness and mechanical response characteristics of the real workpiece material under cutting force, avoiding damage caused by direct contact between the simulated tool 1 and the specimen. It can also be used to calibrate and test the closed-loop control function when performing dynamic stiffness measurement.

[0027] A multi-dimensional force sensor 4 can be installed at the load path nodes of the spindle unit. The load path refers to the force transmission link from the application source (spindle drive end) through the simulated tool 1, the contact interface, to the simulated specimen 2 and the worktable 5. Nodes are typical locations in this link where the force flow is concentrated and not branched (such as the connection interface between the simulated tool 1 and the spindle, or the support interface between the simulated specimen 2 and the worktable 5). Placing the multi-dimensional force sensor 4 at the load path nodes of the spindle unit allows the sensor to directly bear and measure the force during transmission, thereby obtaining a force signal that truly reflects the load magnitude and avoiding measurement deviations caused by structural additional forces or transmission attenuation due to distance from the node. The testing dimensions of the multi-dimensional force sensor 4 can be selected according to requirements and are not limited here.

[0028] The displacement sensor can be installed at the front end of the machine tool spindle, close to the clamping part of the simulated tool 1. It can directly monitor the minute displacement deformation generated at the front end of the spindle when it is subjected to axial or radial loads. By collecting the real-time displacement data of the displacement sensor, accurate position feedback information can be provided for subsequent stiffness calculation and position compensation.

[0029] The control unit can be a data acquisition and real-time controller (such as an industrial PLC or industrial computer). The control unit is connected to the multi-dimensional force sensor 4 and the displacement sensor to receive the force and displacement signals collected by the multi-dimensional force sensor 4 and the displacement sensor in real time. The connection method can be through signal cable or wireless, which is not limited here. This connection relationship enables the control unit to synchronously obtain the force-displacement corresponding data during the loading process, providing an input basis for subsequent stiffness calculation and adaptive control.

[0030] It should be noted that, in this embodiment of the disclosure, the device further includes: A servo drive unit is connected to the control unit and the simulated tool 1.

[0031] The servo drive unit can be a CNC system for machine tools, or it can be used as a power execution component of a testing device. One end is connected to the control unit to receive displacement compensation commands generated by the control unit; the other end is connected to the simulated tool 1 to drive the simulated tool 1 to perform precise micro-feed motion along the axial direction according to the received commands.

[0032] It should be noted that, in this embodiment of the disclosure, the multi-dimensional force sensor 4 is disposed between the simulated tool 1 and the spindle.

[0033] The multidimensional force sensor 4 can be installed at the connection interface between the simulated tool 1 and the machine tool spindle, i.e., at the force transmission path. This allows the multidimensional force sensor 4 to directly measure all the forces transmitted from the spindle drive end to the contact surface via the simulated tool 1, avoiding force attenuation and phase lag caused by deformation of the elastic pad or changes in the stiffness of the specimen support, thus obtaining more realistic and synchronous load data.

[0034] In summary, the adaptive spindle unit load testing device proposed in this embodiment directly measures the actual force at the load path nodes through the multi-dimensional force sensor 4, eliminating the need for indirect calculation based on offline calibration of the elastic element 3 and thus eliminating calibration errors. The control unit synchronously collects force and displacement signals, offsetting the influence of changes in the elastic element 3's characteristics on control accuracy and providing real-time feedback of test data. Furthermore, it integrates high-precision constant force loading and dynamic load simulation onto the same platform, improving the constant force control accuracy of the testing device.

[0035] Example 2 Figure 2This is a flowchart of an adaptive spindle element load testing method based on any of the above-described adaptive spindle element load testing devices, according to an embodiment of this application. Figure 2 As shown, the method includes: Step 1: Apply a load to the simulated tool.

[0036] During the test, the control unit sends motion commands to the servo drive unit to drive the simulated tool to move axially and contact the elastic element on the surface of the simulated test piece, so that the contact force gradually increases to the preset target value. The simulated tool can be used as the force application terminal to produce a controllable squeezing effect on the simulated test piece, thereby forming a force state on the spindle unit that is similar to the actual machining conditions.

[0037] For example, it can be attached Figure 1 The testing apparatus is arranged. In this embodiment, the simulated specimen can be a truncated cone structure or other required shapes, which are not limited here. The surface of the simulated specimen is covered with an elastic element, which can be a rubber gasket. The multi-dimensional force sensor can be a force gauge with a range of ±1000N, integrated between the simulated tool and the spindle, and can directly measure the dynamic force borne by the simulated tool during cutting. The multi-dimensional force sensor can rotate with the spindle and can transmit real-time force signals to the control unit wirelessly. The displacement sensor can be an eddy current sensor with a resolution of 0.1μm, which can be installed at the front end of the spindle for real-time monitoring of the displacement deformation of the spindle during loading. The spindle under test is selected to obtain the rated load and the theoretical value of the spindle static stiffness. The control unit can be a data acquisition and real-time controller, and can be an industrial PLC or industrial control computer, etc., depending on the requirements; the control unit can be connected to the force sensor receiver, displacement sensor and servo drive unit for acquiring signals, running control algorithms and generating displacement compensation commands containing the final calculated target displacement.

[0038] Step 2: Obtain the initial force change value measured by the multi-dimensional force sensor and the initial displacement change value measured by the displacement sensor, and determine the initial stiffness value based on the initial force change value and the initial displacement change value.

[0039] First, the force change measured by the multi-dimensional force sensor at the beginning of the loading stage and the displacement change measured by the displacement sensor at the same stage can be obtained. These two changes reflect the correspondence between force and displacement in the initial contact between the simulated tool and the elastic element. Then, based on the force change and displacement change, the initial stiffness value can be obtained, which serves as the reference parameter for subsequent adaptive control.

[0040] It should be noted that, in this embodiment of the disclosure, the step of acquiring the initial force change value detected by the multi-dimensional force sensor and the initial displacement change value detected by the displacement sensor, and determining the initial stiffness value based on the initial force change value and the initial displacement change value, includes: driving the simulated tool to contact the elastic element on the surface of the simulated specimen through the servo drive unit to load the simulated specimen, and monitoring the force exerted by the simulated tool on the simulated specimen by the spindle during the loading process through the multi-dimensional force sensor, and monitoring the displacement of the simulated tool during the loading process through the displacement sensor; when the force measurement value of the multi-dimensional force sensor reaches a first force value, the displacement measurement value corresponding to the displacement sensor is a first displacement value; when the displacement measurement value of the displacement sensor reaches a second displacement value, the force measurement value corresponding to the multi-dimensional force sensor is a second force value; wherein, the first force value and the second displacement value are preset values; the difference between the first force value and the second force value is used as the initial force change value, and the difference between the first displacement value and the second displacement value is used as the initial displacement change value; the ratio of the initial force change value to the initial displacement change value is used as the initial stiffness value.

[0041] First, a servo drive unit brings a simulated tool into low-speed contact with the elastic element on the surface of the simulated specimen, and continuous loading is applied. During loading, two preset thresholds are set: a first force value (force trigger value) and a second displacement value (displacement trigger value). When the force measured by the multi-dimensional force sensor reaches the first force value, the reading of the displacement sensor at this time is recorded as the first displacement value; when the displacement measured by the displacement sensor reaches the second displacement value, the reading of the multi-dimensional force sensor at this time is recorded as the second force value. Then, the difference between the first force value and the second force value is calculated as the initial force change, and the difference between the first displacement value and the second displacement value is calculated as the initial displacement change. Finally, the ratio of the force change to the displacement change is used as the initial stiffness value. By acquiring the force-displacement correspondence through trigger points of two different physical quantities, the random errors that may be introduced by single-point measurement are avoided, providing a reliable stiffness benchmark for subsequent adaptive control.

[0042] Specifically, during initial stiffness identification, before the test begins, a servo drive unit can be used to drive a simulated cutting tool to contact the elastic pad at a low speed. When the multi-dimensional force sensor detects that the compressive force has reached a preset first force value... At that time, record the first displacement value corresponding to the current displacement sensor. Subsequently, the servo drive unit applies a small displacement to the simulated tool. The multi-dimensional force sensor updates the extrusion pressure to a second force value. At this time, the initial force change value is generated. ,Right now Stiffness can be identified online by calculation. ,Will The value is used as the initial stiffness value. After obtaining the first force value, the second force value, the first displacement value, and the second displacement value, the simulated tool can be retracted to the first displacement value. Location, will This serves as the stiffness benchmark under the current testing conditions. .

[0043] Step 3: Obtain the current force change value measured by the multi-dimensional force sensor and the current displacement change value measured by the displacement sensor, and determine the current stiffness value based on the current force change value and the current displacement change value.

[0044] During the test, the current force change measured by the multi-dimensional force sensor and the current displacement change measured by the displacement sensor are continuously acquired. Based on the current force change and the current displacement change, the current stiffness value is determined. The current stiffness value reflects the instantaneous stiffness characteristics of the contact interface under the current loading state and can be used for subsequent adaptive compensation calculations.

[0045] It should be noted that, in this embodiment of the disclosure, the step of acquiring the current force change value measured by the multi-dimensional force sensor and the current displacement change value measured by the displacement sensor, and determining the current stiffness value based on the current force change value and the current displacement change value, includes: driving the simulated tool to contact the elastic element on the surface of the simulated specimen through the servo drive unit, and monitoring the force exerted by the simulated tool on the simulated specimen by the spindle during loading through the multi-dimensional force sensor, and monitoring the displacement of the simulated tool during loading through the displacement sensor; when the force measurement value of the multi-dimensional force sensor reaches a first force value, the displacement measurement value corresponding to the displacement sensor is the first displacement value; acquiring the current force value measured by the multi-dimensional force sensor and the current displacement value measured by the displacement sensor; using the difference between the first force value and the current force value as the current force change value, and the difference between the first displacement value and the current displacement value as the current displacement change value; and using the ratio of the current force change value to the current displacement change value as the current stiffness value.

[0046] First, a servo drive unit drives a simulated cutting tool to establish stable contact with an elastic element on the surface of the simulated specimen, and continuous loading is applied. During this process, a multi-dimensional force sensor monitors the contact force exerted by the simulated cutting tool on the simulated specimen in real time, while a displacement sensor simultaneously monitors the axial displacement of the simulated cutting tool.

[0047] When the force measurement value of the multi-dimensional force sensor first reaches a preset first force value, it represents a known reference state during the loading process (usually selected within the linear deformation zone of the elastic element). Subsequently, at any moment during loading, the system acquires the current force value measured by the multi-dimensional force sensor and the current displacement value measured by the displacement sensor. Next, it calculates the current force change and the current displacement change. Both changes are relative to the same reference point (the state corresponding to the first force value), eliminating the influence of the initial contact position and initial preload. Finally, the ratio of the current force change to the current displacement change is taken as the current stiffness value. The current stiffness value reflects the average tangential stiffness of the contact interface from the reference point to the current loading point. Because the reference point is fixed and selected within the linear segment, this method can track instantaneous stiffness fluctuations caused by nonlinearity of the elastic element material, creep, temperature changes, or spindle deformation in real time, providing accurate and timely parameter input for subsequent adaptive displacement compensation.

[0048] Step 4: Based on the current force change value, current displacement change value, initial stiffness value, and current stiffness value, determine the target displacement amount that the simulated tool needs to be adjusted.

[0049] It should be noted that, in this embodiment of the disclosure, determining the target displacement amount that the simulated tool needs to be adjusted based on the current force change value, the current displacement change value, the initial stiffness value, and the current stiffness value includes: determining a displacement proportional term error value based on the current force change value and the current stiffness value; determining a cumulative displacement error based on the force change value and the current stiffness value within each time period; determining a displacement feedforward error value based on the current force change value and the initial stiffness value; and determining the target displacement amount that the simulated tool needs to be adjusted based on the displacement proportional term error value, the cumulative displacement error, and the displacement feedforward error value.

[0050] Adaptive compensation calculations can be performed on the target displacement, specifically as follows: Divide the current force change value by the current stiffness value to obtain the displacement proportional term error, which is used to compensate for the current deviation; considering historical cumulative errors, accumulate the ratios of the force change value to the current stiffness value within each control cycle to form a cumulative displacement error sum, thus eliminating steady-state residual errors; divide the current force change value by the initial stiffness value to obtain the displacement feedforward error value, which is used to predict and compensate for rapidly changing loads using the initial reference stiffness; finally, superimpose the displacement proportional term error, the cumulative displacement error sum, and the displacement feedforward error value to obtain the target displacement amount that the simulated tool needs to adjust. The calculation formula is as follows: (1) In the formula, The distance, i.e. the target displacement, needs to be precisely adjusted for the nth control cycle. The change between the current force value and the target force value is given, where the target force value is the expected load value preset for the test, and the current force value is the actual force value collected in real time by the multi-dimensional force sensor. This is the current stiffness value; This is the integral coefficient, used to adjust the strength of the integral action, and is measured based on the system response during debugging. For the first The change in force over a period of time; To control the cycle; This is the feedforward gain, and its value depends on the magnitude of the force change and the qualitative nature of the system's dynamic response.

[0051] It should be noted that during debugging When setting the target force, a small initial value can be given, and then the target force can be adjusted. The force tracking curve can be observed, and adjustments can be made based on the steady-state error elimination. The value is taken until the system overshoots or oscillates, at which point... Value max. (This can be done...) The optimal value for this system is 50%-80% of the maximum value. The value was then determined. The system was then tested under constant force conditions for an extended period to verify the reasonableness of the chosen value.

[0052] In this embodiment of the disclosure, The possible values ​​for are:

[0053] in, and These are the set force value change thresholds, and It is related to the spindle's rated load, dynamic characteristics, and test objectives. This calculation method combines the immediacy of proportional control, the cumulative elimination capability of integral control, and the rapid response characteristics of feedforward control, enabling the displacement adjustment to quickly track dynamic force changes while ensuring long-term loading stability.

[0054] For example, under constant load conditions, the first force value is set to... (For example, 5% of the target force), control cycle Integral coefficient This embodiment is a constant load test, where the current force change is 0, and the feedforward gain is... The formula for calculating the target displacement is simplified to: (2) Under dynamic load conditions, the spindle can be started to rotate, and an initial force value can be applied first. At a preset time, update based on the change in target force. The target force is stepped to a new value. The control unit can calculate the change between the current force and the target force in real time during each control cycle, and generate a displacement compensation command containing the target displacement according to the above formula. The displacement compensation command is then sent to the machine tool to drive the simulated tool to respond quickly.

[0055] It should be noted that, in this embodiment of the present disclosure, the method further includes: generating a displacement compensation command based on the target displacement; sending the displacement compensation command to a servo drive unit, wherein the servo drive unit controls the simulated tool to achieve the target displacement according to the displacement compensation command.

[0056] The control unit generates a corresponding displacement compensation command based on the calculated target displacement (i.e., the distance the simulated tool needs to adjust). This command includes information on the displacement direction (feed or retraction) and magnitude. The control unit sends the displacement compensation command to the servo drive unit via an industrial communication interface. Upon receiving the command, the servo drive unit drives the machine tool's servo axis motor according to the displacement parameters in the command, causing the simulated tool to perform precise micro-feed or retraction movements along the axial direction. This ensures that the actual displacement of the simulated tool reaches the target displacement, thereby changing the actual contact force and bringing the current force value closer to the target force value. This process achieves a closed-loop connection from control algorithm output to mechanical action execution and is the final execution stage of adaptive load adjustment.

[0057] It should be noted that, in this embodiment of the disclosure, determining the current stiffness value and updating the current stiffness value in real time includes: generating test result data through the control unit, wherein the test result data includes: force change data during the loading process, stiffness change data, and spindle static stiffness data.

[0058] During the real-time determination and updating of the current stiffness value, the control unit also undertakes the functions of data recording and output. Specifically, the control unit organizes the force values ​​from the multi-dimensional force sensor, the displacement values ​​from the displacement sensor, and the dynamically updated stiffness values ​​collected and calculated during the test to generate structured test result data. This data can include three parts: force value changes over time or displacement during loading (reflecting load tracking), contact stiffness changes during loading (reflecting the stiffness evolution characteristics of the elastic component and contact interface), and spindle static stiffness evaluation data (the spindle's own stiffness extracted through loading / unloading curves or specific algorithms). Data can also be generated as needed based on actual conditions; no restrictions are placed here. The testing process not only achieves real-time control but also automatically generates the raw data for the test report.

[0059] During the test, the current stiffness can be dynamically calculated at fixed intervals (e.g., 60 seconds) using the real-time force signal from the multi-dimensional force sensor and the real-time displacement signal from the displacement sensor. This enables real-time updates of the stiffness, providing real-time parameters for load compensation and ensuring that the control parameters always match the actual values.

[0060] It should be noted that, in this embodiment of the disclosure, the method further includes: when a preset test termination condition is met, the control unit issues a retraction command to terminate loading, wherein the test termination condition includes: the test runtime reaches a preset time threshold.

[0061] During the test run, the control unit continuously monitors the current test duration and compares it with a preset time threshold. When the test run duration reaches or exceeds the preset time threshold, it is considered to have met the preset test termination condition. At this point, the control unit stops executing the loading command and instead actively generates a tool retraction command and sends it to the servo drive unit. The servo drive unit drives the simulated tool to move in the opposite direction according to the tool retraction command, causing it to disengage from the elastic element on the surface of the simulated specimen, thereby terminating the loading process. This ensures that each test has a consistent loading duration, facilitating cross-sectional comparison of test results from different batches or under different working conditions. In addition to the test run duration reaching the preset time threshold, the preset test termination condition may also include: real-time force exceeding the upper limit or falling below the lower limit of the safe force value; real-time displacement exceeding the maximum allowable stroke; force fluctuation exceeding the set threshold or failing to converge for an extended period; abnormal sensor signal or communication interruption; online identification of the current stiffness value exceeding the normal range; and manual triggering of an emergency stop command by the operator. The above conditions can be used individually or in combination, and loading will terminate when any one of them is met.

[0062] In summary, the adaptive spindle unit load testing method proposed in this embodiment directly sets multi-dimensional force sensors at load path nodes to acquire actual contact forces in real time, replacing the indirect calculations of traditional offline calibration and eliminating calibration errors. It dynamically calculates and updates the current stiffness using real-time force and displacement signals, combining online stiffness updates and adaptive compensation calculations to achieve high-precision force closed-loop control. The control unit synchronously acquires force and displacement signals and generates displacement compensation commands, which are sent to the servo drive unit to drive the simulated tool to perform micro-feed, achieving real-time precise control of the force-position hybrid closed loop. Simultaneously, a feedforward strategy is introduced to improve step response speed and suppress overshoot, enabling the system to track dynamic load spectra. Finally, the control unit automatically outputs test results including force changes, stiffness changes, and spindle static stiffness data, and automatically retracts the tool when a preset time threshold is reached. This integrates high-precision constant force loading and dynamic load simulation onto the same platform, providing an integrated testing solution for the comprehensive performance evaluation of the spindle unit, achieving high-precision, high-repeatability, and high-stability static and dynamic load testing.

[0063] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0064] Any process or method description in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more executable instructions for implementing custom logic functions or processes, and the scope of the preferred embodiments of this application includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as should be understood by those skilled in the art to which embodiments of this application pertain.

[0065] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

[0066] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0067] It should be noted that when a component is described as "fixed to" another component, it can be directly on the other component or may have a component in between. When a component is considered "connected to" another component, it can be directly connected to the other component or may have a component in between. When a component is considered "set on" another component, it can be directly set on the other component or may have a component in between. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0068] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all modifications and variations falling within the scope of the invention.

Claims

1. A self-adapting spindle unit load testing device, characterized by, The device includes: Simulated cutting tool, connected to the machine tool spindle; A simulated specimen is placed on the worktable of the device, and an elastic element is provided on the surface of the simulated specimen. A multi-dimensional force sensor is installed at the load path node of the main spindle unit; A displacement sensor is installed at the front end of the machine tool spindle; The control unit is connected to the multi-dimensional force sensor and the displacement sensor.

2. The apparatus of claim 1, wherein, The device further includes: A servo drive unit, which is connected to the control unit and the simulated tool.

3. The apparatus as described in claim 1, characterized in that, The multidimensional force sensor is positioned between the simulated tool and the spindle.

4. An adaptive spindle unit load testing method based on the adaptive spindle unit load testing device according to any one of claims 1-3, characterized in that, The method includes: Apply a load to the simulated tool; The initial force change value measured by the multi-dimensional force sensor and the initial displacement change value measured by the displacement sensor are obtained, and the initial stiffness value is determined based on the initial force change value and the initial displacement change value. The current force change value measured by the multi-dimensional force sensor and the current displacement change value measured by the displacement sensor are obtained, and the current stiffness value is determined based on the current force change value and the current displacement change value. Based on the current force change value, current displacement change value, initial stiffness value, and current stiffness value, the target displacement amount that the simulated tool needs to be adjusted is determined.

5. The method as described in claim 4, characterized in that, The step of acquiring the initial force change value detected by the multi-dimensional force sensor and the initial displacement change value detected by the displacement sensor, and determining the initial stiffness value based on the initial force change value and the initial displacement change value, includes: The servo drive unit drives the simulated cutting tool to contact the elastic element on the surface of the simulated specimen, thereby loading the simulated specimen. A multi-dimensional force sensor monitors the force exerted by the simulated cutting tool on the simulated specimen during loading, and a displacement sensor monitors the displacement of the simulated cutting tool during loading. When the force measurement value of the multi-dimensional force sensor reaches a first force value, the corresponding displacement measurement value of the displacement sensor is a first displacement value; when the displacement measurement value of the displacement sensor reaches a second displacement value, the corresponding force measurement value of the multi-dimensional force sensor is a second force value. The first force value and the second displacement value are preset values. The difference between the first force value and the second force value is taken as the initial force change value, and the difference between the first displacement value and the second displacement value is taken as the initial displacement change value; The ratio of the initial force change value to the initial displacement change value is used as the initial stiffness value.

6. The method as described in claim 4, characterized in that, The process of acquiring the current force change value measured by the multi-dimensional force sensor and the current displacement change value measured by the displacement sensor, and determining the current stiffness value based on the current force change value and the current displacement change value, includes: The servo drive unit drives the simulated tool to contact the elastic element on the surface of the simulated specimen, and the multi-dimensional force sensor monitors the force exerted by the simulated tool on the simulated specimen during the loading process. The displacement sensor monitors the displacement of the simulated tool during the loading process. When the force measurement value of the multi-dimensional force sensor reaches the first force value, the displacement measurement value of the displacement sensor is the first displacement value. Obtain the current force value measured by the multi-dimensional force sensor and the current displacement value measured by the displacement sensor; The difference between the first force value and the current force value is taken as the current force change value, and the difference between the first displacement value and the current displacement value is taken as the current displacement change value; The ratio of the current force change value to the current displacement change value is used as the current stiffness value.

7. The method as described in claim 4, characterized in that, The step of determining the target displacement adjustment amount for the simulated tool based on the current force change value, current displacement change value, initial stiffness value, and current stiffness value includes: Based on the current force change value and the current stiffness value, determine the displacement ratio term error value; Based on the internal force changes and the current stiffness value in each time period, determine the cumulative displacement error. Based on the current force change value and the initial stiffness value, determine the displacement feedforward error value; The target displacement that the simulated tool needs to be adjusted is determined based on the displacement ratio error value, the cumulative displacement error, and the displacement feedforward error value.

8. The method as described in claim 4, characterized in that, The method further includes: Based on the target displacement, a displacement compensation command is generated; The displacement compensation command is sent to the servo drive unit, which controls the simulated tool to achieve the target displacement based on the displacement compensation command.

9. The method as described in claim 4, characterized in that, The step of determining the current stiffness value and updating the current stiffness value in real time includes: The control unit generates test result data, which includes: force change data, stiffness change data, and spindle static stiffness data during the loading process.

10. The method as described in claim 4, characterized in that, The method further includes: When the preset test termination conditions are met, the control unit issues a retraction command to terminate the loading. The test termination conditions include: the test runtime reaches a preset time threshold.

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