A numerical control machine tool whole machine precision retention acceleration test method and platform

Abstract

The application discloses a kind of numerical control machine tool whole machine precision retention accelerated test test method and platform, belong to numerical control machine tool performance test field.Test method steps include: the cutting load data acquisition of measured machine under normal working condition, "force-heat-vibration-motion" multi-stress loading and machine precision accelerated degradation data acquisition.Test platform mainly includes vibration stress loading system, thermal stress loading system, cutting load simulation loading system and the numerical control machine tool of being measured.The numerical control machine tool whole machine precision retention accelerated test test method and platform of the application, through the synchronous loading of "force-heat-vibration-motion" multi-stress, sufficiently simulates and accelerates machine tool actual service condition, solves the long period, low efficiency problem of obtaining machine precision degradation data under normal working condition, fills the blank of domestic and foreign machine tool whole machine precision retention accelerated test test method and platform.

Description

Technical Field

[0001] This invention belongs to the field of CNC machine tool performance testing technology, specifically relating to an accelerated testing method and platform for the overall accuracy retention of CNC machine tools. Background Technology

[0002] Precision retention is one of the key performance indicators of high-end CNC machine tools, describing the machine tool's ability to maintain its original precision under normal operating conditions. Due to complex factors such as wear, creep, and loosening, the precision of machine tools gradually deteriorates during service. Compared with similar foreign machine tool products, domestically produced high-end CNC machine tools generally exhibit problems such as short precision retention time and poor precision retention capability during service. Precision retention testing is an important means to study, evaluate, and improve the precision retention level of domestically produced machine tools. Currently, on-site tracking testing is often used to test machine tool precision retention, which has drawbacks such as long testing time and low testing efficiency. Therefore, there is an urgent need to invent an accelerated testing method and platform for the overall precision retention of CNC machine tools, enabling the acquisition of the overall precision retention level of the machine tool in a shorter time.

[0003] Currently, there is limited research on machine tool accuracy retention testing methods both domestically and internationally, with studies primarily focusing on the accuracy retention testing of functional components such as ball screws and rotary tables. In 2014, Jing Guofeng et al. from Yantai Huanqiu Machine Tool Accessories Group Co., Ltd. disclosed a detection device for the accuracy retention of CNC rotary tables in patent CN104020716A. This device simulates actual cutting loads on a test bench to detect the accuracy retention of CNC rotary tables, thus improving the testing efficiency to some extent. In 2020, Zu Li et al. from Nanjing University of Science and Technology disclosed a comprehensive evaluation method for the accuracy retention of ball screw pairs in patent CN111735626A. This method accelerates the degradation of accuracy retention by applying axial force and rotational speed to the ball screw pairs.

[0004] Analysis of existing machine tool accuracy retention testing technologies reveals that: (1) there is still a lack of research on accelerated testing of the overall accuracy retention of CNC machine tools, with only research on testing methods for the accuracy retention of some functional components; (2) the currently published testing methods for the accuracy retention of machine tool functional components are based only on simulating actual cutting load loading, without considering the influence of environmental factors such as temperature and vibration on the accuracy degradation of machine tools, resulting in limited accelerated testing effects and an inability to guarantee the consistency of the accelerated degradation mechanism. Summary of the Invention

[0005] The purpose of this invention is to provide an accelerated testing method and platform for the overall accuracy retention of CNC machine tools, addressing the problems mentioned in the background art.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method and platform for accelerated testing of the overall accuracy retention of CNC machine tools, comprising the following steps:

[0007] Step 1: Obtain cutting load data of the machine tool under normal operating conditions and complete the installation and positioning of the test platform;

[0008] Step two: Apply "force-heat-vibration-motion" stress to the machine tool under test to accelerate the degradation of the machine tool's accuracy;

[0009] Step 3: After each loading cycle is completed, test and record the machine tool accuracy degradation data.

[0010] The present invention further explains that the specific method for obtaining the cutting load data of the machine tool under normal operating conditions in step one is as follows:

[0011] Based on information such as the material being processed, spindle speed, feed rate, depth of cut, and tool parameters under normal operating conditions of the machine tool under test, cutting simulation based on standard parts is carried out to obtain the mean, amplitude, and frequency of cutting forces in each of the X / Y / Z axes under normal operating conditions.

[0012] The present invention further explains that in step two, a "force-heat-vibration-motion" stress is applied to the machine tool under test. "Force" refers to the static and dynamic cutting forces in each of the X / Y / Z axes, "heat" refers to the periodic temperature change, "vibration" refers to the overall vibration of the machine tool rather than local vibration, and "motion" refers to the rapid movement of each feed axis of the machine tool. The specific loading process is as follows: according to the stress combination of "heat-vibration-motion", "heat-vibration-static force", and "heat-vibration-dynamic force", the three groups of stresses are applied synchronously in sequence. The above loading process is one loading cycle.

[0013] The present invention further explains that the specific requirements for testing and recording machine tool accuracy degradation data in step three are as follows:

[0014] After one loading cycle is completed, stop loading, test and record the machine tool accuracy; test the machine tool accuracy once after each loading cycle is completed, and repeat loading and testing in this way until the loading cycle is completed and the test ends.

[0015] The present invention further explains that the experimental platform includes a vibration stress loading system, a thermal stress loading system, a lifting mechanism, a cooling unit, a power amplifier, an extended platform, the machine tool under test, and a cutting load loading system, which realizes the loading of force, heat, vibration, and motion stress on the machine tool under test, and meets the above requirements for accelerated testing of the machine tool's overall accuracy retention.

[0016] The present invention further explains that the cutting load loading system includes a dynamic force loading module, a simulated tool holder interface module, a tool holder clamping module, and a static force loading module, thereby realizing the loading of static and dynamic cutting loads on the machine tool.

[0017] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0018] 1) This invention fully considers the impact of environmental stress and working stress on the machine tool's accuracy degradation during service. It proposes an accelerated test method for accuracy retention based on multi-stress loading of "force-heat-vibration-motion". This method can not only ensure the consistency of the machine tool's accuracy degradation mechanism, but also accelerate the degradation of machine tool accuracy to a greater extent, thus achieving scientific and rapid testing of machine tool accuracy retention.

[0019] 2) This invention proposes a technical solution for an accelerated testing platform for the overall precision retention of machine tools, which can realize the synchronous loading of force, heat, vibration and motion stress on the machine tool under test, fully simulate and accelerate the actual service conditions of the machine tool, and provide a reasonable and feasible test platform construction scheme for the accelerated testing of the overall precision retention of machine tools. Attached Figure Description

[0020] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0021] Figure 1 This is a schematic diagram of the initial position of the accelerated test platform for maintaining the overall precision of CNC machine tools.

[0022] Figure 2 This is a schematic diagram of the working position of the accelerated testing platform for maintaining the overall precision of CNC machine tools.

[0023] Figure 3 This is a schematic diagram of the cutting load loading system.

[0024] In the figure: 1 Vibration stress loading system; 2 Thermal stress loading system; 3 Lifting mechanism; 4 Cooling unit; 5 Power amplifier; 6 Extended platform; 7 Machine tool under test; 8 Cutting load on-machine loading system; 9 Dynamic force loading module; 10 Simulated tool holder interface module; 11 Tool holder clamping module; 12 Static force loading module. Detailed Implementation

[0025] The following detailed, non-limiting description of the technical solution of the present invention, in conjunction with preferred embodiments and accompanying drawings, is provided. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0026] Please see Figure 1-3 The present invention provides a technical solution: a test method and platform for accelerated testing of the overall accuracy retention of a CNC machine tool, including a vibration stress loading system 1, a thermal stress loading system 2, a lifting mechanism 3, a cooling unit 4, a power amplifier 5, an extended table 6, the machine tool under test 7, and an on-machine loading system for cutting load 8;

[0027] The cutting load loading system 8 includes a dynamic force loading module 9, a simulated tool holder interface module 10, a tool holder clamping module 11, and a static force loading module 12.

[0028] Hereinafter referred to as "force-heat-vibration-motion".

[0029] An accelerated testing method for the overall accuracy retention of a CNC machine tool includes the following steps:

[0030] Step 1: Obtain cutting load data of the machine tool under normal operating conditions and complete the installation and positioning of the test platform.

[0031] Based on information such as the material being processed, spindle speed, feed rate, depth of cut, and tool parameters under normal operating conditions of the machine tool under test, cutting simulation based on standard parts is carried out to obtain the mean, amplitude, and frequency of cutting forces in each of the X / Y / Z axes under normal operating conditions.

[0032] The machine tool under test 7 is hoisted onto the extended platform 6 using a gantry crane and secured with multi-point bolt connections. The initial geometric accuracy of the machine tool under test 7 is tested and recorded using a laser interferometer. The lifting mechanism 3 is activated to move the thermal stress loading system 2 to the working position, and the bottom surface of the thermal stress loading system 2 is sealed to the extended platform 6.

[0033] Step two: Apply "force-heat-vibration-motion" stress to the machine tool under test 7 to accelerate the degradation of the machine tool's accuracy;

[0034] Based on the cutting load data and acceleration coefficient of the machine tool under normal operating conditions obtained in step 1, the magnitude of the loading force is determined. The three stresses are synchronously loaded sequentially according to the stress combinations of "thermal-vibration-motion," "thermal-vibration-static force," and "thermal-vibration-dynamic force." This loading process constitutes one loading cycle. "Force" refers to the cutting load in each of the X / Y / Z axes, including both static and dynamic cutting loads, which are loaded by the static force loading module 12 and dynamic force loading module 9 of the cutting load simulation system 8, respectively. "Heat" refers to periodic temperature changes, loaded by the thermal stress loading system 2. "Vibration" refers to the overall vibration of the machine tool rather than local vibration, loaded by the vibration stress loading system 1. "Motion" refers to the rapid movement of each feed axis of the machine tool, completed by the rapid movement of each feed axis at a set feed speed.

[0035] The specific loading process is as follows:

[0036] a. Apply a combination of thermal-vibration-motion stress;

[0037] Specifically, the vibration stress loading system 1 is turned on, the vibration acceleration is set to 10 m / s², the vibration amplitude is 1 mm, and the vibration frequency is 50 Hz; the thermal stress loading system 2 is turned on, the room temperature is set to 20 ℃, the temperature change range is 0~40 ℃, and the average temperature change rate is 0.5 ℃ / min; the machine tool under test 7 is turned on, and the machine tool operation program is compiled according to the maximum feed speed of the machine tool to make the X / Y / Z feed axes of the machine tool move rapidly throughout their full stroke, with the feed speed set to 20 m / min; after the "thermal-vibration-motion" stress combination is continuously applied for 160 min, the vibration stress loading system and the thermal stress loading system are turned off, and the movement of the machine tool feed axes is stopped.

[0038] b. Apply a combination of thermal-vibration-static force stress;

[0039] Specifically, the cutting load on-machine loading system 8 is installed, and the base of the cutting load on-machine loading system 8 is fixed on the machine tool worktable. The simulated tool holder interface module 10 is connected to the machine tool spindle, and the tool holder is clamped by the tool holder clamping module. The vibration stress loading system and the thermal stress loading system are turned on, and the above parameter settings are used. The static force loading module 12 is turned on, and a static force of 1500N in the X / Y / Z directions is applied simultaneously. The "thermal-vibration-static force" stress combination is continuously loaded for 160 minutes.

[0040] c. Apply a combination of thermal-vibration-dynamic force stress;

[0041] Specifically, keep the vibration stress loading system and the thermal stress loading system active; loosen the tool holder clamping module 11, activate the dynamic force loading module 9, and simultaneously apply a dynamic force of 200N in the X / Y / Z directions with a force change frequency of 150Hz; after continuously loading the "thermal-vibration-dynamic force" stress combination for 160 minutes, stop loading. The above loading process constitutes one loading cycle, with a total loading time of 480 minutes. If the machine tool malfunctions during the test, loading should be interrupted, and the loading test should continue after troubleshooting.

[0042] Step 3: After each loading cycle is completed, test and record the machine tool accuracy degradation data.

[0043] After one loading cycle, the machine tool's geometric accuracy was tested and recorded using a laser interferometer. Subsequently, the machine tool's accuracy was tested after each loading cycle, and this loading and testing process was repeated until 20 cycles (160 hours) were completed, at which point the experiment concluded.

[0044] During the loading process, the cooling unit 4 continuously cools the vibration stress loading system 1.

[0045] The above steps overcome the problem that the existing technology has no research on accelerated testing of the overall accuracy retention of CNC machine tools, and only research on the accuracy retention testing methods of some functional components exists. At the same time, the influence of environmental factors such as temperature and vibration on the accuracy degradation of machine tools is used to accelerate the testing effect, and the consistency of the accelerated degradation mechanism is ensured.

[0046] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features, and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for accelerated testing of the overall accuracy retention of a CNC machine tool, characterized in that: The method includes the following steps: Step 1: Obtain cutting load data of the machine tool under normal operating conditions and complete the installation and positioning of the test platform; Step 2: Apply "force-heat-vibration-motion" stress to the machine tool under test (7) to accelerate the degradation of the machine tool's accuracy; Step 3: After each loading cycle is completed, test and record the machine tool accuracy degradation data; In step two, a "force-heat-vibration-motion" stress is applied to the machine tool under test. "Force" refers to the static and dynamic cutting forces in each of the X / Y / Z axes, "heat" refers to the periodic temperature change, "vibration" refers to the overall vibration of the machine tool rather than local vibration, and "motion" refers to the rapid movement of each feed axis of the machine tool. The specific loading process is as follows: according to the stress combination of "heat-vibration-motion", "heat-vibration-static force", and "heat-vibration-dynamic force", the three groups of stresses are applied synchronously in sequence. The above loading process is one loading cycle.

2. The accelerated testing method for the overall accuracy retention of a CNC machine tool according to claim 1, characterized in that: The specific method for obtaining the cutting load data of the machine tool under normal operating conditions in step one is as follows: Based on the information of the material being processed, spindle speed, feed rate, depth of cut, and tool parameters under normal operating conditions of the machine tool under test, cutting simulation based on standard parts is carried out to obtain the mean, amplitude, and frequency of cutting forces in each of the X / Y / Z axes under normal operating conditions.

3. The accelerated testing method for the overall accuracy retention of a CNC machine tool according to claim 1, characterized in that: The specific requirements for testing and recording machine tool accuracy degradation data in step three are as follows: After one loading cycle is completed, stop loading, test and record the machine tool accuracy; test the machine tool accuracy once after each loading cycle is completed, and repeat loading and testing until (20) loading cycles are completed, and end the test.

4. The accelerated testing method for the overall accuracy retention of a CNC machine tool according to claim 1, characterized in that: The test platform includes a vibration stress loading system (1), a thermal stress loading system (2), a lifting mechanism (3), a cooling unit (4), a power amplifier (5), an extended platform (6), a machine tool under test (7), and a cutting load loading system (8), which realizes the loading of force, heat, vibration, and motion stress on the machine tool under test, and meets the above requirements for accelerated testing of the machine tool's overall accuracy retention.

5. The accelerated testing method for the overall accuracy retention of a CNC machine tool according to claim 4, characterized in that: The cutting load loading system (8) includes a dynamic force loading module (9), a simulated tool holder interface module (10), a tool holder clamping module (11), and a static force loading module (12), which realizes the loading of static and dynamic cutting loads on the machine tool.

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