Machine tool assembly consistency evaluation method and device

Abstract

The application discloses a machine tool assembly consistency evaluation method and device, and belongs to the field of machine tool assembly. The quality of key components is controlled from subassembly to final assembly through the steps of component dynamic stiffness testing, whole machine dynamic stiffness testing, frequency response function analysis, characteristic frequency range determination, dynamic stiffness data statistics, dynamic stiffness evaluation theoretical value acquisition and dynamic stiffness evaluation. The assembly consistency is tested at each link of assembly. If assembly quality problems or assembly consistency problems are found, the problems can be handled in the early stage, the fault troubleshooting time is shortened, the assembly efficiency is improved, the assembly precision and efficiency of the machine tool are improved, and the quality and performance of the product are ensured.

Description

Technical Field

[0001] This invention relates to the field of machine tool assembly, and in particular to a method for evaluating the consistency of machine tool assembly and an apparatus for implementing the above method. Background Technology

[0002] The performance reliability of complex mechanical systems is ensured through the joint efforts of design, manufacturing, and assembly. Assembly is the final step in manufacturing complex systems and also the most crucial step in ensuring product quality. The quality and consistency of assembly directly determine the final performance of the mechanical structure. For complex mechanical systems like machine tools, the assembly process is even more complex, with significant and difficult-to-quantify human factors influencing the quality and consistency of assembly.

[0003] Assembly consistency of CNC machine tools has become a key factor restricting the development of high-end CNC machine tools in my country. Multiple CNC machine tools manufactured in the same batch have significant differences in processing performance, poor consistency, and poor accuracy retention. Summary of the Invention

[0004] In order to overcome the shortcomings of the prior art, one of the objectives of this invention is to provide a machine tool assembly consistency evaluation method that can improve the assembly accuracy and efficiency of machine tools and ensure the quality and performance of machine tools.

[0005] In order to overcome the shortcomings of the prior art, the second objective of this invention is to provide a machine tool assembly consistency control device that can improve the assembly accuracy and efficiency of machine tools and ensure the quality and performance of machine tools.

[0006] One of the objectives of this invention is achieved through the following technical solution:

[0007] A method for evaluating the consistency of machine tool assembly includes the following steps:

[0008] Dynamic stiffness test of components: The base component, the base-beam component and the spindle box-saddle component are hammered respectively. The hammering point is used as the test point. There are two test points. The two test points are located in different positions. Vibration signals in the corresponding direction near the test point are collected.

[0009] Overall mechanical stiffness test: The spindle box-saddle assembly is installed on the crossbeam, and the turntable assembly is installed on the base. The assembly is hammered, and the hammering point is used as the test point. There are three test points, and the three test points are located in different positions. Vibration signals in the corresponding directions near the test points are collected.

[0010] Frequency response function analysis: take hammering signal as excitation signal, take vibration signal as response signal, calculate the frequency response function between excitation signal and response signal, the horizontal axis is excitation frequency, the vertical axis is response amplitude, record the frequency value at the significant peak in the frequency response function curve of each component and assembly;

[0011] Determination of characteristic frequency range: change the assembly condition of the whole machine, obtain the frequency response function curve under different assembly conditions and the frequency value at the corresponding significant peak, extract the frequency at which the frequency value or response amplitude changes significantly as the characteristic frequency, and determine the range of the characteristic frequency;

[0012] Dynamic stiffness data statistics: statistics of dynamic stiffness curves of multiple machines in the characteristic frequency range;

[0013] Dynamic stiffness evaluation theoretical value acquisition: take the minimum value of dynamic stiffness of the machine in the characteristic frequency range as the dynamic stiffness value, and take the dynamic stiffness value and the characteristic frequency range as the theoretical value of consistency evaluation;

[0014] Dynamic stiffness evaluation: hammer test is carried out on the parts or whole machine to be evaluated, the actual frequency value at the significant peak in the frequency response function curve is extracted according to the test result, the actual frequency value is compared with the theoretical characteristic frequency range, the actual dynamic stiffness value is compared with the theoretical dynamic stiffness value, and the assembly consistency is evaluated according to the two comparison results.

[0015] Further, in the component dynamic stiffness test step, the base component is a base mounting foot support, and the test is carried out after adjusting the level, and the test point is located at the bottom of the base.

[0016] Further, in the component dynamic stiffness test step, the base-beam component is to install the beam on the base component, and the test point is located at the bottom of the beam.

[0017] Further, in the component dynamic stiffness test step, the spindle box-saddle component is tested by hanging the spindle box and saddle component with nylon rope, and the test point is located on the spindle flange surface.

[0018] Further, in the whole machine dynamic stiffness test step, two of the three test points are located on the spindle flange surface, and the other test point is located on the rotary table.

[0019] Further, in the component dynamic stiffness test step and the whole machine dynamic stiffness test step, the frequency of the vibration signal is more than 2.5 times the natural frequency of the component structure or the whole machine structure.

[0020] Further, in the component dynamic stiffness test step and the whole machine dynamic stiffness test step, the number of times of hammering at each test point is multiple, and when the coherence of the vibration signal reaches more than 85%, the vibration signal is collected.

[0021] Further, in the component dynamic stiffness test step and the whole machine dynamic stiffness test step, the hammering directions of the multiple test points are perpendicular.

[0022] Further, in the characteristic frequency range determination step, the changing of the assembly conditions of the whole machine specifically comprises: changing at least one of a bolt pre-tightening torque, a fastener number, an inlay pre-tightening force, and a joint surface roughness.

[0023] The second purpose of the present application is achieved by the following technical solutions:

[0024] A machine tool assembly consistency evaluation device for implementing any of the machine tool assembly consistency evaluation methods described above, the machine tool assembly consistency evaluation device comprising an impact force hammer, an acceleration sensor, and a processor, the impact force hammer applying hammering to components and the whole machine, the acceleration sensor collecting vibration signals generated due to the hammering, and the processor being in communication connection with the acceleration sensor and the vibration signals.

[0025] Compared with the prior art, the machine tool assembly consistency evaluation method of the present application controls the quality of key components from subassembly to final assembly through the steps of component dynamic stiffness test, whole machine dynamic stiffness test, frequency response function analysis, characteristic frequency range determination, dynamic stiffness data statistics, dynamic stiffness evaluation theoretical value acquisition, and dynamic stiffness evaluation, and performs assembly consistency testing at each link of assembly, so that when assembly quality problems or assembly consistency problems are found, they can be handled in the early stage, the fault troubleshooting time is shortened, and the assembly efficiency is improved. The machine tool assembly consistency evaluation method of the present application can improve the assembly precision and efficiency of the machine tool, and ensure the quality and performance of the product. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The flowchart of the machine tool assembly consistency evaluation method of the present application;

[0027] Figure 2 The test item diagram of the machine tool assembly consistency evaluation method of the present application;

[0028] Figure 3 The base component test point schematic diagram of the machine tool assembly consistency evaluation method of the present application;

[0029] Figure 4 The base-beam component test point schematic diagram of the machine tool assembly consistency evaluation method of the present application;

[0030] Figure 5 The spindle box-saddle component test point schematic diagram of the machine tool assembly consistency evaluation method of the present application;

[0031] Figure 6 The whole machine component test point schematic diagram of the machine tool assembly consistency evaluation method of the present application;

[0032] Figure 7 a frequency response function curve between the excitation signal and the response signal;

[0033] Figure 8 a comparison chart of frequency response functions under different assembly conditions;

[0034] Figure 9 a statistical chart of machine tool dynamic stiffness data. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0036] It should be noted that when a component is referred to as being "fixed" to another component, it can be directly on the other component or can be fixed thereto through another intermediate component. When a component is referred to as being "connected" to another component, it can be directly connected to the other component or can be connected thereto through another intermediate component. When a component is referred to as being "disposed" on another component, it can be directly disposed on the other component or can be disposed thereon through another intermediate component. The terms "vertical", "horizontal", "left", "right", and the like used herein are for illustrative purposes only.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0038] Referring to Figure 1 The machine tool assembly consistency evaluation method of the present application comprises the following steps:

[0039] Part dynamic stiffness test: the base part, the base-beam part and the spindle box-saddle part are respectively hammered, the hammering points are taken as test points, the number of test points is two, the positions of the two test points are different, and the vibration signals in the corresponding directions near the test points are collected;

[0040] Whole machine dynamic stiffness test: install the spindle box-saddle component on the crossbeam, install the rotary table component on the base, hammer the assembly, take the hammering point as the test point, the number of test points is three, the positions of the three test points are different, collect the vibration signals in the corresponding directions near the test points;

[0041] Frequency response function analysis: take the hammering signal as the excitation signal, take the vibration signal as the response signal, calculate the frequency response function between the excitation signal and the response signal, the horizontal axis is the excitation frequency, the vertical axis is the response amplitude, record the frequency values at the prominent peaks in the frequency response function curves of each component and the assembly;

[0042] Determination of characteristic frequency range: change the assembly conditions of the whole machine, obtain the frequency response function curves under different assembly conditions and the frequency values at the corresponding prominent peaks, extract the frequencies at which the frequency values or the response amplitudes change significantly as the characteristic frequencies, and determine the range of the characteristic frequencies;

[0043] Dynamic stiffness data statistics: statistics the dynamic stiffness curves of multiple machines in the characteristic frequency range;

[0044] Dynamic stiffness evaluation theoretical value acquisition: take the minimum value of the dynamic stiffness of the machine in the characteristic frequency range as the dynamic stiffness value, and take the dynamic stiffness value and the characteristic frequency range as the theoretical value for consistency evaluation;

[0045] Dynamic stiffness evaluation: hammer test the parts or whole machine to be evaluated, extract the actual frequency values at the prominent peaks in the frequency response function curves according to the test results, compare the actual frequency values with the theoretical characteristic frequency range, compare the actual dynamic stiffness value with the theoretical dynamic stiffness value, and evaluate the assembly consistency according to the two comparison results.

[0046] Specifically, as shown in Figure 2 The test object includes components and whole machines, the components include base components, base-crossbeam components and spindle box-saddle components. Since the machine assembly consistency evaluation method requires an evaluation standard, i.e., a theoretical value, the components and whole machines used in the component dynamic stiffness test and whole machine dynamic stiffness test steps are consistent and qualified, so as to obtain the evaluation standard of the consistent and qualified components and whole machines.

[0047] The base components, base-crossbeam components and spindle box-saddle components are tested in two perpendicular directions, i.e., X and Y directions in this embodiment, and the whole machine is tested in three perpendicular directions, i.e., X, Y and Z directions in this embodiment. The dynamic stiffness tests in different directions are realized by knocking in different directions and collecting vibration signals in different directions.

[0048] As shown in Figure 3As shown, when testing the base part, the base part is supported by the base mounting feet, and the test is performed after the base part is adjusted to be horizontal, and the test points are located at the bottom of the base. The arrow direction in the figure indicates the direction of the excitation force (hammering force), and the position of the arrow indicates the position of the excitation point. The sampling points are located near the excitation point. The two test points are test point 1 and test point 2, both of which are located at the bottom of the base. Test point 1 is in the x direction of the machine tool, and test point 2 is in the y direction of the machine tool.

[0049] As shown in Figure 4 , when testing the beam-base part, the beam is installed on the base part, and the two test points are test point 1 and test point 2, both of which are located at the bottom of the beam. Test point 1 is in the x direction of the machine tool, and test point 2 is in the y direction of the machine tool.

[0050] As shown in Figure 5 , when testing the spindle box-saddle part, the spindle box and the saddle part are lifted by nylon lifting ropes, and the test points are located on the spindle flange surface. The two test points are test point 1 and test point 2, both of which are located on the spindle flange surface. Test point 1 is in the x direction of the machine tool, and test point 2 is in the y direction of the machine tool.

[0051] As shown in Figure 6 , when testing the whole machine, the spindle box-saddle part is installed on the beam, and the rotary table part is installed on the base. The three test points are test point 1, test point 2, and test point 3. Test points 1 and 2 are located on the spindle flange surface. Test point 1 is in the x direction of the machine tool, and test point 2 is in the y direction of the machine tool. Test point 3 is on the rotary table, and the direction is the radial direction of the workbench.

[0052] During testing, the structure is hammered at the specified point and direction, and the acceleration sensor is used to collect vibration signals in the corresponding direction near the hammering position. The sampling frequency reaches more than 2.5 times the characteristic natural frequency of the structure, and preferably in this embodiment, the sampling frequency reaches more than 2.56 times the characteristic natural frequency of the structure. During testing, each test point is hammered 3 times. When the coherence is good, it reaches 85% or more, the data meets the requirements, and the data is collected. Preferably, in this embodiment, the coherence reaches more than 95%.

[0053] In the frequency response function analysis step, the frequency response function curve is as shown in Figure 7 .

[0054] In the characteristic frequency range determination step, the assembly conditions of the whole machine are changed, specifically at least one of the bolt pre-tightening torque, the number of fasteners, the inlay pre-tightening force, and the roughness of the joint surface. The frequency response functions under different assembly conditions are compared as shown in Figure 8 .

[0055] In the dynamic stiffness data statistics step, the statistical machine tools include components and whole machines, and the components and whole machines are consistent and qualified. The dynamic stiffness curves of the statistical multiple machine tools in the characteristic frequency range are as shown in FIG. 2. The minimum value of the dynamic stiffness of the machine tool in the characteristic frequency range is taken as the dynamic stiffness value. The dynamic stiffness value and the characteristic frequency range are taken as the theoretical values for the consistency evaluation. Figure 9

[0056] In the embodiment, the theoretical values for the consistency evaluation of the machine tools in a series are shown in Table 1.

[0057] Table 1

[0058]

[0059] In the dynamic stiffness evaluation step, the parts to be evaluated can be components or whole machines. According to the specific types and categories of the parts to be evaluated, for example, which one of the base component, base-cross beam component, spindle box-saddle component and whole machine, the corresponding methods in the component dynamic stiffness test and whole machine dynamic stiffness test steps are adopted for the hammer test. According to the test results, the actual frequency values at the significantly prominent peak values in the frequency response function curve are extracted. The actual frequency values are compared with the theoretical characteristic frequency range, and the actual dynamic stiffness values are compared with the theoretical dynamic stiffness values. The assembly consistency is evaluated according to the two comparison results.

[0060] The application also relates to a machine tool assembly consistency evaluation device for implementing the machine tool assembly consistency evaluation method. The machine tool assembly consistency evaluation device comprises an impact force hammer, an acceleration sensor and a processor. The impact force hammer is used for applying hammering to components and whole machines. The acceleration sensor is used for collecting vibration signals generated due to the hammering. The processor is in communication connection with the acceleration sensor and is in the vibration signals.

[0061] The impact force hammer is used for applying excitation. The model of the impact force hammer is 086C03, the sensitivity is 2.314 mV / N, the range is ±2200 N, and the resonance frequency is greater than or equal to 22 KHz.

[0062] The acceleration sensor is a one-way acceleration sensor.

[0063] Compared with the prior art, the machine tool assembly consistency evaluation method can control the quality of the key components from the subassembly to the final assembly, can perform assembly consistency tests at each link of the assembly, can handle the assembly quality problems or assembly consistency problems in the early stage when the problems are found, can shorten the troubleshooting time, and can improve the assembly efficiency. The machine tool assembly consistency evaluation method can improve the assembly precision and efficiency of the machine tool, and can ensure the quality and performance of the product.

[0064] ​The above embodiments only express several implementation manners of the present application, the description is more specific and detailed, but cannot be understood as the limitation of the scope of the patent. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the present application, several modifications and improvements can be made, which are equivalent modifications and evolutions of the above embodiments according to the essential technology of the present application, and these all belong to the protection scope of the present application.

Claims

1. A method for evaluating the consistency of machine tool assembly, characterized in that, Includes the following steps: Component dynamic stiffness test: The unassembled base component, base-beam component and spindle box-saddle component were hammered respectively. The hammering point was used as the test point. There were two test points. The two test points were located in different positions. Vibration signals in the corresponding direction near the test point were collected. Overall mechanical stiffness test: The spindle box-saddle assembly is installed on the crossbeam, and the turntable assembly is installed on the base. The assembly is hammered, and the hammering point is used as the test point. There are three test points, and the three test points are located in different positions. Vibration signals in the corresponding directions near the test points are collected. Frequency response function analysis: Using the hammer impact signal as the excitation signal and the vibration signal as the response signal, calculate the frequency response function between the excitation signal and the response signal. The horizontal axis represents the excitation frequency and the vertical axis represents the response amplitude. Record the frequency values ​​of the significant peaks in the frequency response function curves of each component and assembly. Determine the characteristic frequency range: Change the assembly conditions of the whole machine to obtain the frequency response function curves under different assembly conditions and the frequency values ​​at multiple corresponding prominent peaks. Extract the frequencies where the frequency values ​​or response amplitudes change significantly as characteristic frequencies and determine the range of characteristic frequencies. Dynamic stiffness data statistics: Statistically analyze the dynamic stiffness curves of multiple machine tools within the characteristic frequency range; Theoretical value acquisition for dynamic stiffness evaluation: The minimum dynamic stiffness of the machine tool within the characteristic frequency range is taken as the dynamic stiffness value, and the dynamic stiffness value and the characteristic frequency range are taken as the theoretical values ​​for consistency evaluation. Dynamic stiffness evaluation: Hammer impact test is performed on the part or whole machine to be evaluated. Based on the test results, the actual frequency value of the significant peak in the frequency response function curve is extracted. The actual frequency value is compared with the theoretical characteristic frequency range. The actual dynamic stiffness value is compared with the theoretical dynamic stiffness value. Based on the two comparison results, assembly consistency test is performed at each stage of assembly.

2. The machine tool assembly consistency evaluation method according to claim 1, characterized in that: In the component dynamic stiffness test step, the base component is supported by base mounting feet, and the test is carried out after the base is adjusted to be level. The test point is located at the bottom of the base.

3. The machine tool assembly consistency evaluation method according to claim 1, characterized in that: In the component dynamic stiffness test step, the base-beam component is formed by mounting the beam on the base component, and the test point is located at the bottom of the beam.

4. The machine tool assembly consistency evaluation method according to claim 1, characterized in that: In the component dynamic stiffness test step, the spindle box and slide saddle component are suspended by nylon ropes during the test, and the test point is located on the spindle flange surface.

5. The machine tool assembly consistency evaluation method according to claim 1, characterized in that: In the overall mechanical stiffness test procedure, two of the three test points are located on the spindle flange face, and the other test point is located on the turntable.

6. The machine tool assembly consistency evaluation method according to claim 1, characterized in that: In the component dynamic stiffness test step and the whole machine dynamic stiffness test step, the frequency of the vibration signal is more than 2.5 times the natural frequency of the component structure or the whole machine structure.

7. The machine tool assembly consistency evaluation method according to claim 1, characterized in that: In the component dynamic stiffness test step and the whole body dynamic stiffness test step, the number of hammer blows at each test point is multiple. When the vibration signal coherence reaches more than 85%, the vibration signal is collected.

8. The machine tool assembly consistency evaluation method according to claim 1, characterized in that: In the component dynamic stiffness test step and the whole-body dynamic stiffness test step, the hammering directions at multiple test points are perpendicular.

9. The machine tool assembly consistency evaluation method according to claim 1, characterized in that: In the step of determining the characteristic frequency range, changing the assembly conditions of the whole machine specifically involves changing at least one of the following: bolt preload torque, number of fasteners, insert preload force, and surface roughness.

10. A machine tool assembly consistency evaluation device, used to implement the machine tool assembly consistency evaluation method as described in any one of claims 1-9, characterized in that: The machine tool assembly consistency evaluation device includes an impact hammer, an acceleration sensor, and a processor. The impact hammer applies hammering to the components and the whole machine. The acceleration sensor collects the vibration signal generated by the hammering. The processor is communicatively connected to the acceleration sensor and is in contact with the vibration signal.

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