Machine tool assembly consistency evaluation method and device

Abstract

The invention discloses a machine tool assembly consistency evaluation method and device, and belongs to the field of machine tool assembly.The machine tool assembly consistency evaluation method includes 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, dynamic stiffness evaluation and the like. Quality of key components is controlled from subassembly to final assembly, assembly consistency testing is carried out in all links of assembly, if assembly quality problems or assembly consistency problems are found, earlier-stage processing can be carried out, troubleshooting time is shortened, assembly efficiency is improved, assembly precision and efficiency of a machine tool can be improved, and quality and performance of products can be guaranteed.

Description

Technical Field

[0001] The invention relates to the field of machine tool assembly, and in particular to a machine tool assembly consistency evaluation method and a device for implementing the method. Background Art

[0002] The performance reliability of complex mechanical systems is jointly guaranteed by the three links of design, manufacturing and assembly. The assembly of mechanical systems is the last link in the manufacture of complex systems and the most important link in ensuring product quality. The quality and consistency of assembly directly determine the final performance of the mechanical structure. For complex mechanical systems such as machine tools, the assembly process is increasingly complex, the human factor has a large impact and is difficult to quantitatively evaluate, and the assembly quality and consistency are difficult to guarantee.

[0003] The 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 produced from the same batch have large differences in processing performance, poor consistency, and poor precision retention. Summary of the invention

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

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

[0006] One of the purposes of the present invention is achieved by the following technical solution:

[0007] A machine tool assembly consistency evaluation method comprises the following steps:

[0008] Component dynamic stiffness test: hammer the base component, base-beam component and spindle box-saddle component respectively, and use the hammering point as the test point. There are two test points, and the two test points are at different positions. Collect vibration signals in the corresponding directions near the test points;

[0009] The dynamic stiffness test of the whole body: the spindle box-saddle component is installed on the crossbeam, the turntable component is installed on the base, and the assembly is hammered. The hammering point is used as the test point. There are three test points, and the three test points are located at different positions. The vibration signals in the corresponding directions near the test points are collected;

[0010] Frequency response function analysis: Using hammer signal as excitation signal and vibration signal as response signal, calculate the frequency response function between the excitation signal and the response signal. The horizontal axis is the excitation frequency and the vertical axis is the response amplitude. Record the frequency value of the significant peak in the frequency response function curve of each component and assembly.

[0011] Determine the 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 ​​of multiple corresponding prominent peaks, 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 machine tools within the characteristic frequency range;

[0013] Acquisition of the theoretical value of dynamic stiffness evaluation: The minimum value of the 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 ​​of consistency evaluation;

[0014] Dynamic stiffness evaluation: Perform a hammer test on the parts or the whole machine to be evaluated, extract the actual frequency value at the significantly prominent peak in the frequency response function curve according to the test results, compare the actual frequency value with the theoretical characteristic frequency range, compare the actual dynamic stiffness value with the theoretical dynamic stiffness value, and evaluate the assembly consistency based on the two comparison results.

[0015] Furthermore, in the component dynamic stiffness test step, the base component is supported by base mounting feet, and the test is performed after adjusting the level, and the test point is located at the bottom of the base.

[0016] Furthermore, in the component dynamic stiffness test step, the base-beam component is a base component in which the beam is installed on the base component, and the test point is located at the bottom of the beam.

[0017] Furthermore, in the component dynamic stiffness test step, the spindle box and the saddle component are hoisted with a nylon hoisting rope during the spindle box-saddle component test, and the test point is located on the spindle flange surface.

[0018] Further, in the whole body 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 turntable.

[0019] Furthermore, in the component dynamic stiffness testing step and the whole machine dynamic stiffness testing 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] Furthermore, in the component dynamic stiffness test step and the whole dynamic stiffness test step, each test point is hammered a majority of the time, and the vibration signal is collected when the coherence of the vibration signal reaches more than 85%.

[0021] Furthermore, in the component dynamic stiffness testing step and the whole body dynamic stiffness testing step, the hammering directions of the multiple test points are perpendicular to each other.

[0022] Furthermore, in the step of determining the characteristic frequency range, the changing of the assembly conditions of the whole machine specifically includes: changing at least one of the bolt pre-tightening torque, the number of fasteners, the pre-tightening force of the insert, and the roughness of the bonding surface.

[0023] The second object of the present invention is achieved by adopting the following technical solution:

[0024] A machine tool assembly consistency evaluation device is used to implement any one of the above-mentioned machine tool assembly consistency evaluation methods, the machine tool assembly consistency evaluation device includes an impact hammer, an acceleration sensor and a processor, the impact hammer applies hammering to components and the entire machine, the acceleration sensor collects vibration signals generated by the hammering, and the processor is communicatively connected to the acceleration sensor and is in the vibration signal.

[0025] Compared with the prior art, the machine tool assembly consistency evaluation method of the present invention controls the quality of key components from subassembly to final assembly through the steps of component dynamic stiffness test, whole body dynamic stiffness test, frequency response function analysis, determination of characteristic frequency range, dynamic stiffness data statistics, acquisition of dynamic stiffness evaluation theoretical value and dynamic stiffness evaluation, and other steps. It performs assembly consistency test in each link of assembly, and if assembly quality problems or assembly consistency problems are found, they can be processed in the early stage, shortening the troubleshooting time and improving assembly efficiency. It can improve the assembly accuracy and efficiency of machine tools and ensure the quality and performance of products. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a flow chart of the machine tool assembly consistency evaluation method of the present invention;

[0027] Figure 2 It is a test item diagram of the machine tool assembly consistency evaluation method of the present invention;

[0028] Figure 3 A schematic diagram of the base component measuring points of the machine tool assembly consistency evaluation method of the present invention;

[0029] Figure 4 A schematic diagram of the base-beam component measuring points of the machine tool assembly consistency evaluation method of the present invention;

[0030] Figure 5 A schematic diagram of measuring points of a spindle box-saddle component of a machine tool assembly consistency evaluation method of the present invention;

[0031] Figure 6 It is a schematic diagram of measuring points of the whole machine components of the machine tool assembly consistency evaluation method of the present invention;

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

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

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

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] It should be noted that when a component is referred to as being "fixed to" another component, it may be directly on the other component or there may be another intermediate component through which it is fixed. When a component is considered to be "connected to" another component, it may be directly connected to the other component or there may be another intermediate component at the same time. When a component is considered to be "set on" another component, it may be directly set on the other component or there may be another intermediate component at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0038] See also Figure 1 The present application provides a machine tool assembly consistency evaluation method, comprising the following steps:

[0039] Component dynamic stiffness test: hammer the base component, base-crossbeam component and spindle box-saddle component respectively, and use the hammering points as test points. There are two test points at different locations, and collect vibration signals in the corresponding directions near the test points.

[0040] The dynamic stiffness test of the whole body: install the spindle box-saddle component on the crossbeam, install the turntable component on the base, hammer the assembly, and use the hammering point as the test point. There are three test points at different locations, and collect vibration signals in the corresponding directions near the test points;

[0041] Frequency response function analysis: Using hammer signal as excitation signal and vibration signal as response signal, calculate the frequency response function between the excitation signal and the response signal. The horizontal axis is the excitation frequency and the vertical axis is the response amplitude. Record the frequency value of the significant peak in the frequency response function curve of each component and assembly.

[0042] Determine the 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 ​​of multiple corresponding prominent peaks, 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;

[0043] Dynamic stiffness data statistics: statistics of dynamic stiffness curves of multiple machine tools within the characteristic frequency range;

[0044] Acquisition of the theoretical value of dynamic stiffness evaluation: The minimum value of the 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 ​​of consistency evaluation;

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

[0046] Specifically, Figure 2 As shown, the objects to be tested include components and complete machines, and the components include base components, base-crossbeam components, and spindle box-saddle components. Since the machine tool assembly consistency evaluation method requires an evaluation standard, that is, a theoretical value, consistent components and complete machines are used in the component dynamic stiffness test and the complete dynamic stiffness test steps to obtain the evaluation standard for consistent components and complete machines.

[0047] The base component, the base-crossbeam component and the spindle box-saddle component are tested for dynamic stiffness in two mutually perpendicular directions, which are the X and Y directions in this embodiment, and the whole machine is tested for dynamic stiffness in three mutually perpendicular directions, which are the X, Y and Z directions in this embodiment. Dynamic stiffness tests in different directions are achieved by tapping in different directions and collecting vibration signals in different directions.

[0048] like Figure 3As shown in the figure, when testing the base component, the base component is supported by the base installation feet, and the test is performed after adjusting the level. The test point is located at the bottom of the base. The direction of the arrow in the figure indicates the direction of the excitation force (hammer force), the position of the arrow is the position of the excitation point, and the sampling point is near the excitation point. The two test points are measuring point 1 and measuring point 2, both of which are located at the bottom of the base, measuring point 1 is the x-direction of the machine tool, and measuring point 2 is the y-direction of the machine tool.

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

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

[0051] like Figure 6 As shown in the figure, when testing the whole machine, the spindle box-saddle component is installed on the crossbeam, and the turntable component is installed on the base. The three test points are measuring point 1, measuring point 2 and measuring point 3. Measuring points 1 and 2 are both located on the spindle flange surface. Measuring point 1 is in the x-direction of the machine tool, and measuring point 2 is in the y-direction of the machine tool. Measuring point 3 is on the turntable, and the direction is the radial direction of the worktable.

[0052] During the test, a hammer is used to hit the specified point and direction of the structure, and an 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 natural frequency of the structural characteristics. Preferably, in this embodiment, the sampling frequency reaches more than 2.56 times the natural frequency of the structural characteristics. During the test, each measuring point is hammered 3 times. When the coherence is good, reaching more than 85%, 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 follows: Figure 7 shown.

[0054] In the step of determining the characteristic frequency range, changing the assembly conditions of the whole machine specifically includes: changing at least one of the bolt pre-tightening torque, the number of fasteners, the pre-tightening force of the insert, and the roughness of the joint surface. Figure 8 shown.

[0055] In the dynamic stiffness data statistics step, the machine tools included in the statistics include components and complete machines, which are components and complete machines with qualified consistency. The dynamic stiffness curves of multiple machine tools within the characteristic frequency range are as follows: Fig. 9 As shown in the figure, the minimum value of the dynamic stiffness of the machine tool within 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 consistency evaluation.

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

[0057] Table 1

[0058]

[0059] In the dynamic stiffness evaluation step, the part to be evaluated may be a component or a complete machine. According to the specific type and category of the part to be evaluated, for example, whether it is a base component, a base-crossbeam component, a spindle box-saddle component, or a complete machine, a hammer test is performed using the corresponding methods in the component dynamic stiffness test and the complete machine dynamic stiffness test steps. According to the test results, the actual frequency value at the significantly prominent 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, and the assembly consistency is evaluated based on the two comparison results.

[0060] The present application also relates to a machine tool assembly consistency evaluation device, which is used to implement the above-mentioned machine tool assembly consistency evaluation method. The machine tool assembly consistency evaluation device includes an impact hammer, an acceleration sensor and a processor. The impact hammer applies hammering to components and the entire machine, and the acceleration sensor collects vibration signals generated by the hammering. The processor is communicated with the acceleration sensor and is in vibration signal.

[0061] The impact hammer is used to apply excitation, the 086C03 model hammer has a sensitivity of 2.314mV / N, a range of ±2200N, and a resonance frequency ≥22KHz.

[0062] The acceleration sensor is a unidirectional acceleration sensor.

[0063] Compared with the prior art, the machine tool assembly consistency evaluation method of the present invention controls the quality of key components from subassembly to final assembly through the steps of component dynamic stiffness test, whole body dynamic stiffness test, frequency response function analysis, determination of characteristic frequency range, dynamic stiffness data statistics, acquisition of dynamic stiffness evaluation theoretical value and dynamic stiffness evaluation, and other steps. It performs assembly consistency test in each link of assembly, and if assembly quality problems or assembly consistency problems are found, they can be processed in the early stage, shortening the troubleshooting time and improving assembly efficiency. It can improve the assembly accuracy and efficiency of machine tools and ensure the quality and performance of products.

[0064] The above embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which are equivalent modifications and improvements made to the above embodiments based on the essential technology of the present invention, and all of them belong to the protection scope of the present invention.

Claims

1. A machine tool assembly consistency evaluation method, characterized in that: The following steps are involved: Component dynamic stiffness test: hammer the base component, base-beam component and spindle box-saddle component respectively, and use the hammering point as the test point. There are two test points, and the two test points are at different positions. Collect vibration signals in the corresponding directions near the test points; The dynamic stiffness test of the whole body: the spindle box-saddle component is installed on the crossbeam, the turntable component is installed on the base, and the assembly is hammered. The hammering point is used as the test point. There are three test points, and the three test points are located at different positions. The vibration signals in the corresponding directions near the test points are collected; Frequency response function analysis: Using hammer signal as excitation signal and vibration signal as response signal, calculate the frequency response function between the excitation signal and the response signal. The horizontal axis is the excitation frequency and the vertical axis is the response amplitude. Record the frequency value of the significant peak in the frequency response function curve of each component and assembly. Determine the 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 ​​of multiple corresponding prominent peaks, 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; Dynamic stiffness data statistics: statistics of dynamic stiffness curves of multiple machine tools within the characteristic frequency range; Acquisition of the theoretical value of dynamic stiffness evaluation: The minimum value of the 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 ​​of consistency evaluation; Dynamic stiffness evaluation: Perform a hammer test on the parts or the whole machine to be evaluated, extract the actual frequency value at the significantly prominent peak in the frequency response function curve according to the test results, compare the actual frequency value with the theoretical characteristic frequency range, compare the actual dynamic stiffness value with the theoretical dynamic stiffness value, and evaluate the assembly consistency based on the two comparison results.

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 the base installation foot, and the test is performed after adjusting the level, and 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 a base component in which the beam is installed 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 the saddle component are hoisted with a nylon hoisting rope during the spindle box-saddle component 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 whole 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 turntable.

6. The machine tool assembly consistency evaluation method according to claim 1, characterized in that: In the component dynamic stiffness testing step and the whole machine dynamic stiffness testing 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 dynamic stiffness test step, each test point is hammered a plurality of times, and the vibration signal is collected when the coherence of the vibration signal reaches more than 85%.

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

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

10. A machine tool assembly consistency evaluation device, used to implement the machine tool assembly consistency evaluation method according to any one of claims 1 to 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 components and the entire machine. The acceleration sensor collects vibration signals generated by the hammering. The processor is connected to the acceleration sensor for communication and is in the vibration signal.

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