Ultrasonic-assisted machining tool wear measurement system and tool wear mechanism research method

Abstract

This invention proposes a measurement system for ultrasonic-assisted machining tool wear and a method for studying tool wear mechanisms. The measurement system includes a cutting system, a force feedback system, and an imaging system. The cutting system performs ultrasonic-assisted machining on the workpiece. The force feedback system monitors the cutting force data of the cutting tool collected by a force gauge in real time. The imaging system records the machining images of the cutting tool in real time and calculates the tool wear in real time. The method for studying tool wear mechanisms utilizes the above measurement system to perform dry and cooled two-dimensional ultrasonic-assisted cutting processes, respectively, to obtain the tool wear amounts VB and Vb, and calculate the attenuation coefficient α. The obtained attenuation coefficient α is then applied to the dry two-dimensional ultrasonic-assisted cutting process. The beneficial effects of this invention are: this measurement system and research method can observe the tool wear and cutting force during ultrasonic-assisted cutting of difficult-to-machine materials in cooled machining processes, providing a reference for the study of tool wear mechanisms in cooled machining.

Description

Technical Field

[0001] This invention relates to the field of ultrasonic-assisted machining technology, specifically to an ultrasonic-assisted machining tool wear measurement system and a method for studying tool wear mechanism. Background Technology

[0002] Difficult-to-machine materials such as titanium-aluminum superalloys and nickel-based superalloys have high specific strength, high temperature strength and fracture toughness, good room temperature plasticity and creep resistance, and good oxidation resistance. Among them, titanium-aluminum superalloys have become candidate materials for hot-end parts of new-generation aero-engines, such as impellers and casings.

[0003] While high-performance titanium-aluminum superalloys improve the performance of aerospace structural components, their high cutting forces, high cutting temperatures, difficulty in chip breakage, and tendency to generate accumulated chips and burrs lead to significant problems such as low machining efficiency, severe tool wear, and poor surface finish. In recent years, some scholars have begun to study ultrasonic-assisted milling technology for titanium-aluminum superalloys. Ultrasonic-assisted machining has attracted widespread attention both domestically and internationally due to its ability to reduce cutting forces, decrease tool wear, improve surface quality, and suppress machining damage. However, the tool wear mechanism in ultrasonic-assisted machining is still under investigation due to the inherent properties of titanium-aluminum superalloys. Common tool wear studies typically involve online measurement of cutting forces combined with offline imaging to measure tool wear, thereby exploring the tool wear mechanism. However, this approach cannot record the tool wear formation process in real time and cannot reveal the relationship between tool wear formation and cutting forces. Currently, a small number of scholars have used a combination of high-speed cameras and force gauges to study the right-angle cutting process of one-dimensional ultrasonic-assisted ceramic matrix composites (see Chinese Patent CN 115781939). They record the process of the cutting edge interacting with the material using a high-speed microscopic observation system and monitor the cutting force using an online cutting force measurement system. However, the methods provided by the aforementioned patent are only applicable to in-depth research on the processing damage and mechanisms of hard and brittle materials like one-dimensional ultrasonic-assisted ceramic matrix composites. Furthermore, the right-angle cutting experiment is a dry cutting method, lacking rigor and scientific validity for studying the tool wear mechanism under ultrasonic-assisted water-cooled machining of difficult-to-machine materials. In summary, there is a lack of research on tool wear in the actual machining of two-dimensional ultrasonic-assisted difficult-to-machine materials, especially titanium-aluminum alloys, which severely restricts the elucidation of the tool wear mechanism during ultrasonic-assisted milling of titanium-aluminum alloys.

[0004] The main problems in current research are: 1. Difficult-to-machine materials such as titanium-aluminum superalloys and nickel-based superalloys are mainly used in the aerospace field due to their material properties, and require a high-efficiency and high-precision machining technology to improve machining efficiency and quality;

[0005] 2. Difficult-to-machine materials such as titanium-aluminum high-temperature alloys and nickel-based high-temperature alloys are lightweight and difficult-to-machine alloy materials. During the machining process, the tool wear is severe and the tool needs to be replaced frequently. However, the relationship between the tool wear formation process and the cutting force is still unclear.

[0006] 3. There is currently no effective method for observing tool wear during two-dimensional ultrasonic-assisted cooling machining of difficult-to-cut materials such as titanium-aluminum superalloys and nickel-based superalloys (cutting fluid is ejected during the cooling process, making tool wear difficult to observe). Summary of the Invention

[0007] In view of this, the present invention provides an online measurement system for wear of ultrasonic-assisted machining tools, including a cutting system, a force feedback system, and an imaging system;

[0008] The cutting system includes a five-axis vertical CNC machining center, a two-dimensional ultrasonic vibration tool holder, a non-contact power transmission device, an ultrasonic power supply, and cutting tools.

[0009] The cutting tool is connected to the two-dimensional ultrasonic vibration tool holder, and the two-dimensional ultrasonic vibration tool holder and the non-contact power transmission device are sequentially fixed on the spindle of the five-axis vertical CNC machining center; the ultrasonic power supply is connected to the non-contact power transmission device, and the five-axis vertical CNC machining center is used to drive the cutting tool to rotate. The ultrasonic power supply transmits electrical energy to the two-dimensional ultrasonic vibration tool holder through the non-contact power transmission device, thereby enabling the two-dimensional ultrasonic vibration tool holder to output ultrasonic waves and transmit vibrations to the cutting tool during rotation, thereby realizing axial vibration-assisted cutting and tangential vibration-assisted cutting of the cutting tool;

[0010] The force feedback system includes a force gauge, a charge amplifier, a data acquisition card, and a computer. The force gauge is fixed on the fixed table of a five-axis vertical CNC machining center, and the workpiece is fixed on the force gauge. The force gauge is connected to the data acquisition card via the charge amplifier, and the data acquisition card is connected to the computer. The force gauge collects cutting force data from the cutting tool in real time during the cutting process, and the computer monitors the cutting force data collected by the force gauge online in real time.

[0011] The imaging system includes a high-speed camera and a processor. The high-speed camera is connected to the processor. The high-speed camera is used to record images of the cutting tool in real time. The processor analyzes the images acquired by the high-speed camera and calculates the wear of the cutting tool in real time.

[0012] Furthermore, the five-axis vertical CNC machining center drives the cutting tool to perform dry machining and cooling machining.

[0013] Furthermore, the cutting tool is a multi-circular carbide end mill.

[0014] Furthermore, the two-dimensional ultrasonic vibration knife handle is a two-dimensional longitudinal torsion ultrasonic vibration knife handle.

[0015] Furthermore, the workpiece is made of Ti2AlNb alloy material.

[0016] Furthermore, the processor also includes a memory for storing processing images captured by a high-speed camera and for the processor to calculate the wear of the cutting tool.

[0017] Furthermore, the computer is also connected to the memory and the processor, and the computer displays the cutting force data it detects and the wear of the cutting tool calculated by the processor in real time.

[0018] This invention also provides a method for online measurement of wear of ultrasonic-assisted machining tools, which uses the above-mentioned online measurement system for wear of ultrasonic-assisted machining tools:

[0019] The method includes the following steps:

[0020] S1: Install the workpiece on the force measuring instrument of the force feedback system, and install the cutting tool on the two-dimensional ultrasonic vibration tool holder;

[0021] S2. According to the set cutting parameters, the five-axis vertical CNC machining center drives the cutting tool to process the workpiece in a dry machining manner until the machining depth reaches half of the predetermined machining depth. The force feedback system records the cutting force in real time, and the imaging system calculates the dry machining wear amount VB of the cutting tool in real time.

[0022] S3: Replace with a new cutting tool. The five-axis vertical CNC machining center uses the same cutting parameters as in step two, with the cutting tool driven by the cooling method of spraying cutting fluid to process the workpiece until the machining depth reaches half of the predetermined machining depth. The force feedback system records the magnitude of the cutting force F in real time. After the machining depth reaches half of the predetermined machining depth, remove the cutting tool and measure the cooling wear amount Vb of the cutting tool.

[0023] S4: Calculate the attenuation coefficient α of the cooling process for cutting tools relative to the dry process, where α = Vb / VB;

[0024] S5: Input the attenuation coefficient α into the processor, and use a five-axis vertical CNC machining center to process the workpiece again in a dry machining mode. The dry machining wear amount VB of the cutting tool is calculated in real time by the imaging system, and the processor calculates the simulated wear amount Vc of the cooling machining mode in real time, where Vc = α * VB. The computer correlates the simulated wear amount Vc of the cooling machining mode with the cutting force F in step 3 in real time to obtain the numerical function relationship between the simulated wear amount Vc of the cooling machining mode and the cutting force F of the cutting tool, so as to study the wear mechanism of the cutting tool in the cooling machining mode of difficult-to-cut materials under ultrasonic assisted cutting conditions.

[0025] Furthermore, in steps S2, S3, and S4 above, when the five-axis vertical CNC machining center drives the cutting tool to cut the workpiece, the two-dimensional ultrasonic vibration tool holder transmits ultrasonic vibration during the rotation of the cutting tool, thereby realizing axial vibration-assisted cutting and tangential vibration-assisted cutting of the cutting tool.

[0026] Furthermore, the calculation methods for the dry machining wear amount VB and the cool machining wear amount Vb are as follows:

[0027] VB = (VB1 + VB2 + ... + VB) n ) / n;

[0028] Among them VB n The wear amount of the nth peripheral cutting edge of the cutting tool during dry machining;

[0029] Vb = (Vb1 + Vb2 + ... + Vb) n ) / n;

[0030] Vb n The amount of wear on the nth peripheral edge of the cutting tool during cooling processing.

[0031] The beneficial effects of the ultrasonic-assisted machining tool wear online measurement system and method of the present invention are as follows:

[0032] (1) The cutting system of the ultrasonic-assisted machining tool wear online measurement system can process the workpiece by rotary milling combined with ultrasonic assistance, so that the cutting system can process difficult-to-cut materials (such as titanium-aluminum high-temperature alloys and nickel-based high-temperature alloys). The cutting system can be applied in the aerospace field and is a high-efficiency and high-precision machining technology that can improve the processing efficiency and quality of difficult-to-cut materials.

[0033] (2) The ultrasonic-assisted machining tool wear online measurement system includes a force feedback system and an imaging system. It can observe the tool wear during ultrasonic-assisted cutting of difficult-to-machine materials, and correlate the tool wear with the cutting force in real time. It provides a reference for the study of the tool wear mechanism of ultrasonic-assisted machining of difficult-to-machine materials. The overall method is simple and feasible, and it is suitable for promotion in the field of ultrasonic-assisted machining.

[0034] (3) The online measurement method for wear of ultrasonic-assisted machining tools can analyze the wear coefficient of two-dimensional ultrasonic-assisted water-cooled machining tools relative to dry machining of difficult-to-cut materials. At the same time, it can simulate the tool wear and cutting force during the cooling process of two-dimensional ultrasonic-assisted dry machining, thereby effectively restoring the tool wear process of two-dimensional ultrasonic-assisted cooling machining. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the structure of an ultrasonic-assisted machining tool wear measurement system according to the present invention.

[0036] Figure 2 This is a flowchart of a method for studying the wear mechanism of ultrasonic-assisted machining tools in this invention.

[0037] In the diagram: 1. Cutting system, 2. Force feedback system, 3. Imaging system, 11. Five-axis vertical CNC machining center, 12. Two-dimensional ultrasonic vibration tool holder, 13. Non-contact power transmission device, 14. Ultrasonic power supply, 15. Carbide end mill, 16. Workpiece, 21. Force gauge, 22. Charge amplifier, 23. Data acquisition card, 24. Computer, 31. High-speed camera, 32. High-magnification optical lens, 33. Processor. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0039] Please refer to Figure 1 An ultrasonic-assisted machining tool wear measurement system in an embodiment of the present invention includes a cutting system 1, a force feedback system 2, and an imaging system 3.

[0040] The cutting system 1 includes a five-axis vertical CNC machining center 11, a two-dimensional ultrasonic vibration tool holder 12, a non-contact power transmission device 13, an ultrasonic power supply 14, and a cutting tool. The workpiece 16 to be processed is fixed to the fixed table of the five-axis vertical CNC machining center 11 by AB glue. The workpiece 16 is a difficult-to-cut material. In this embodiment, the cutting tool is a φ10mm multi-circular edge carbide end mill 15, and the material of the workpiece 16 is Ti2AlNb alloy.

[0041] The carbide end mill 15 is connected to the two-dimensional ultrasonic vibration tool holder 12; the ultrasonic vibration output of the two-dimensional ultrasonic vibration tool holder 12 achieves longitudinal and torsional vibration through its structure, thereby realizing axial vibration-assisted cutting and tangential vibration-assisted cutting; the ultrasonic power supply 14 transmits electrical energy to the two-dimensional ultrasonic vibration tool holder 12 through the non-contact power transmission device 13; the two-dimensional ultrasonic vibration tool holder 12 and the non-contact power transmission device 13 are sequentially fixed on the spindle of the five-axis vertical CNC machining center. In this embodiment, the five-axis vertical CNC machining center is a Mikron 800U, the two-dimensional ultrasonic vibration tool holder is a two-dimensional longitudinal-torsional tool holder with an amplitude of 10μm and a frequency of 40kHz, which can realize axial and tangential vibration, and the ultrasonic power supply has automatic frequency tracking with a range of 10~100kHz.

[0042] The force feedback system 2 includes a force meter 21, a charge amplifier 22, a data acquisition card 23, and a computer 24. In this embodiment, the sampling frequency of the force feedback system 2 is not less than 20kHz, and the force measurement range is not less than 10KN. The real-time cutting force signal during the two-dimensional ultrasonic assisted cutting process is detected and the data is post-processed by the dedicated software of the force feedback system in the computer, so as to obtain the maximum value, average value and real-time fluctuation curve of the cutting force.

[0043] The imaging system 3 includes a high-speed camera 31, a data storage device, and a processor 33. The high-speed camera 31 has a high-magnification optical lens 32 at its front end. In this embodiment, the high-speed camera 31 has a resolution of at least 1920×1200 and captures at least 2380 images per second. The high-magnification optical lens 32 is a wide-angle lens that records in real-time tool wear images of multiple peripheral edges of the carbide end mill 15 during the two-dimensional ultrasonic-assisted cutting process. The processor 33 is used to perform image analysis on the tool wear images to analyze the amount of tool wear during the cutting process. The storage device 33 is used to store the machining images captured by the high-speed camera and the wear amount of the cutting tool calculated by the processor. The computer 24 is also connected to the storage device and the processor 33, and displays in real-time the cutting force data it detects and the wear amount of the cutting tool calculated by the processor 33.

[0044] Please refer to Figure 2 The present invention provides a method for studying the wear mechanism of ultrasonic-assisted machining tools, utilizing the aforementioned ultrasonic-assisted machining tool wear measurement system. The method includes the following steps:

[0045] S1: In the five-axis vertical CNC machining center 11 Mikron 800U machine tool, the workpiece 16 is fixed to the force measuring instrument 21 by AB glue. After installing the two-dimensional ultrasonic vibration tool holder 12 and the non-contact power transmission device 13 on the machine tool spindle, the φ10mm carbide end mill is installed on the tool holder.

[0046] S2. The cutting parameters are set, including feed rates of 40, 60, and 80 mm / min, cutting depths of 0.4, 0.6, and 0.8 mm, and ultrasonic vibration amplitudes of 0, 4, and 8 μm. The five-axis vertical CNC machining center 11 drives the cutting tool to process the workpiece 16 in a dry machining manner according to the cutting parameters until the machining depth reaches half of the predetermined machining depth. During the above process, the force feedback system 2 records the cutting force in real time, and the imaging system 3 calculates the dry machining wear amount VB of the cutting tool in real time.

[0047] S3: Replace the cutting tool. The five-axis vertical CNC machining center uses the same cutting parameters as in step S2 and sprays cutting fluid for cooling to drive the cutting tool to process the workpiece until the machining depth reaches half of the predetermined machining depth. The force feedback system 2 records the magnitude of the cutting force F in real time. After the machining depth reaches half of the predetermined machining depth, remove the cutting tool and use an image instrument with a coordinate value difference ≤ (2.5+L / 100)μ to measure the cooling wear amount Vb of the cutting tool.

[0048] S4: Calculate the attenuation coefficient α of the cooling process for cutting tools relative to the dry process, where α = Vb / VB;

[0049] S5: Input the attenuation coefficient α into the processor, and use the five-axis vertical CNC machining center 11 to process the workpiece again in dry machining mode. The dry machining wear amount VB of the cutting tool is calculated in real time by the imaging system 3, and the processor 33 calculates the simulated wear amount Vc of the cooling machining mode in real time, where Vc=α*VB. The computer 24 correlates the simulated wear amount Vc of the cooling machining mode with the cutting force F in step 3 in real time to obtain the numerical function relationship between the simulated wear amount Vc of the cooling machining mode and the cutting force F of the cutting tool, so as to study the wear mechanism of the cutting tool in the cooling machining mode of difficult-to-cut materials under ultrasonic assisted cutting conditions.

[0050] Understandably, in steps S2, S3, and S4 above, when the five-axis vertical CNC machining center 11 drives the cutting tool to cut the workpiece, the two-dimensional ultrasonic vibration tool holder 12 transmits ultrasonic vibration to the cutting tool during the rotation process, thereby realizing axial vibration-assisted cutting and tangential vibration-assisted cutting of the cutting tool.

[0051] The dry machining wear amount VB and the cool machining wear amount Vb are both calculated by averaging the wear amounts of all peripheral cutting edges. That is, the calculation methods for VB and Vb are as follows:

[0052] VB = (VB1 + VB2 + ... + VB) n ) / n;

[0053] Among them VB n The wear amount of the nth peripheral cutting edge of the cutting tool during dry machining;

[0054] Vb = (Vb1 + Vb2 + ... + Vb) n ) / n;

[0055] Vb n The amount of wear on the nth peripheral edge of the cutting tool during cooling processing.

[0056] In this document, the directional terms such as front, back, top, and bottom are defined based on the location of the components in the accompanying drawings and their relative positions to each other, solely for the purpose of clarity and convenience in expressing the technical solution. It should be understood that the use of these directional terms should not limit the scope of protection claimed in this application.

[0057] Where there is no conflict, the above embodiments and features described herein can be combined with each other.

[0058] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for studying the wear mechanism of ultrasonic-assisted machining tools, characterized in that, The research method employs the following measurement system, which includes a cutting system, a force feedback system, and an imaging system; The cutting system includes a five-axis vertical CNC machining center, a two-dimensional ultrasonic vibration tool holder, a non-contact power transmission device, an ultrasonic power supply, and a cutting tool. The cutting tool is connected to the two-dimensional ultrasonic vibration tool holder, which is sequentially fixed to the spindle of the five-axis vertical CNC machining center along with the non-contact power transmission device. The ultrasonic power supply is connected to the non-contact power transmission device. The five-axis vertical CNC machining center drives the cutting tool to rotate. The ultrasonic power supply transmits electrical energy to the two-dimensional ultrasonic vibration tool holder via the non-contact power transmission device, thereby causing the two-dimensional ultrasonic vibration tool holder to output ultrasonic waves that transmit vibration to the cutting tool during rotation. This achieves axial vibration-assisted cutting and tangential vibration-assisted cutting. The five-axis vertical CNC machining center drives the cutting tool to perform dry machining and cooling machining. The force feedback system includes a force gauge, a charge amplifier, a data acquisition card, and a computer. The force gauge is fixed on the fixed table of a five-axis vertical CNC machining center, and the workpiece is fixed on the force gauge. The force gauge is connected to the data acquisition card through the charge amplifier, and the data acquisition card is connected to the computer. The force gauge collects the cutting force data of the cutting tool in real time during the cutting process, and the computer monitors the cutting force data collected by the force gauge online in real time. The imaging system includes a high-speed camera and a processor. The high-speed camera is connected to the processor. The high-speed camera is used to record the machining images of the cutting tool in real time. The processor analyzes the images acquired by the high-speed camera and calculates the wear of the cutting tool in real time. The research method includes the following steps: S1: Install the workpiece on the force measuring instrument of the force feedback system, and install the cutting tool on the two-dimensional ultrasonic vibration tool holder; S2. According to the set cutting parameters, the five-axis vertical CNC machining center drives the cutting tool to process the workpiece in a dry machining manner until the machining depth reaches half of the predetermined machining depth. The force feedback system records the cutting force in real time, and the imaging system calculates the dry machining wear amount VB of the cutting tool in real time. S3: Replace with a new cutting tool. The five-axis vertical CNC machining center uses the same cutting parameters as in step S2 and sprays cutting fluid for cooling to drive the cutting tool to process the workpiece until the machining depth reaches half of the predetermined machining depth. The force feedback system records the magnitude of the cutting force F in real time. When the machining depth reaches half of the predetermined machining depth, remove the cutting tool and measure the cooling wear Vb of the cutting tool. S4: Calculate the attenuation coefficient α of the cooling process for cutting tools relative to the dry process, where α = Vb / VB; S5: Input the attenuation coefficient α into the processor, and use a five-axis vertical CNC machining center to process the workpiece again in a dry machining mode. The dry machining wear amount VB of the cutting tool is calculated in real time by the imaging system, and the processor calculates the simulated wear amount Vc of the cooling machining mode in real time, where Vc=α*VB. The computer correlates the simulated wear amount Vc of the cooling machining mode with the cutting force F in step S3 in real time to obtain the numerical function relationship between the simulated wear amount Vc of the cooling machining mode and the cutting force F of the cutting tool, so as to study the wear mechanism of the cutting tool in the cooling machining mode of difficult-to-cut materials under ultrasonic assisted cutting conditions.

2. The method for studying the wear mechanism of ultrasonic-assisted machining tools according to claim 1, characterized in that, The cutting tool is a multi-circular carbide end mill.

3. The method for studying the wear mechanism of ultrasonic-assisted machining tools according to claim 1, characterized in that, The two-dimensional ultrasonic vibration tool holder is a two-dimensional longitudinal torsion ultrasonic vibration tool holder.

4. The method for studying the wear mechanism of ultrasonic-assisted machining tools according to claim 1, characterized in that, The workpiece is made of Ti2AlNb alloy.

5. The method for studying the wear mechanism of ultrasonic-assisted machining tools according to claim 1, characterized in that, The processor also includes a memory for storing processing images captured by a high-speed camera and for the processor to calculate the wear of the cutting tool.

6. The method for studying the wear mechanism of ultrasonic-assisted machining tools according to claim 5, characterized in that, The computer is also connected to the memory and the processor, and the computer displays the cutting force data it detects and the wear of the cutting tool calculated by the processor in real time.

7. The method for studying the wear mechanism of ultrasonic-assisted machining tools according to claim 1, characterized in that, In steps S2, S3, and S4 above, when the five-axis vertical CNC machining center drives the cutting tool to cut the workpiece, the two-dimensional ultrasonic vibration tool holder transmits ultrasonic vibration during the rotation of the cutting tool, realizing axial vibration-assisted cutting and tangential vibration-assisted cutting of the cutting tool.

8. The method for studying the wear mechanism of ultrasonic-assisted machining tools according to claim 7, characterized in that, The calculation methods for the dry machining wear amount VB and the cool machining wear amount Vb are as follows: VB=(VB1+VB2+……VB n ) / n; Among them VB n The wear amount of the nth peripheral cutting edge of the cutting tool during dry machining; Vb=(Vb1+Vb2+……Vb n ) / n; Vb n The amount of wear on the nth peripheral edge of the cutting tool during cooling processing.

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