Innovative Dual Ultrasonic-Assisted Diamond Wire Saw System Design
A dual ultrasonic-assisted reciprocating diamond wire saw cutting device has been designed. The process actions were broken down, subsystems were identified, and the technical parameters were established. After conducting a finite element analysis, it was confirmed that the support frame meets the design requirements. Additionally, a composite ultrasonic amplitude transformer was designed, and its effectiveness was validated through modal analysis and experiments. This device is capable of improving cutting quality and efficiency while also extending the lifespan of the wire saw.
01 Introduction
Hard and brittle metallic materials, as well as non-metallic and composite materials, are widely used in various industries due to their remarkable properties, such as high strength, high temperature resistance, and wear resistance. Cutting is the primary processing technology for these materials, accounting for about 40% of the total production cost. Currently, the dominant method for cutting these materials is diamond wire saw processing, which requires high efficiency and excellent surface integrity. This method also aims to extend the lifespan of the cutting tools.
In recent years, the demand for improved cutting quality and efficiency has led to the development of ultrasonic-assisted diamond wire saw cutting technology. By incorporating ultrasonic assistance into the diamond wire saw cutting process, studies have demonstrated significant improvements in sawing efficiency and surface quality, as well as prolonged service life for the saw wire.
Ultrasonic-assisted diamond wire saw cutting technology, with its unique cutting capabilities, has important applications across various fields, including photovoltaics, semiconductors, stone processing, jewelry making, ceramics, glass, and non-conductive metals. However, while several types of ultrasonic-assisted diamond wire saw cutting equipment are currently available on the market, many of these devices utilize a single ultrasonic wave for processing. This leaves considerable room for improvement in both efficiency and quality.
Therefore, conducting in-depth research on dual-ultrasonic-assisted diamond wire saw cutting devices is essential, as it will provide significant theoretical insights and practical engineering guidance.
Diamond wire sawing technology was developed earlier in other countries than in China, leading to more advanced precision cutting techniques for hard and brittle materials. These countries focus not only on equipment development but also on enhancing surface quality, minimizing micro-damage, and improving microstructural properties. Although China’s diamond wire sawing technology for hard and brittle materials emerged later, the country has made rapid progress in this field, narrowing the gap with more advanced foreign technologies as its overall national strength has increased.
In recent years, Chinese scholars have conducted extensive research on ultrasonic-assisted diamond wire sawing. This research primarily investigates the effects of ultrasonic assistance on material removal rates, cutting forces, surface morphology, surface roughness, subsurface damage, and wire wear. However, the study and application of dual-ultrasonic-assisted diamond wire sawing technology remain relatively limited.
Therefore, the development of dual-ultrasonic-assisted diamond wire sawing technology and associated process equipment with independent intellectual property rights is crucial for the advancement of China’s equipment manufacturing industry. This innovation will also contribute to the progress of national defense science and technology, aerospace development, and the revitalization of civilian industries.
02 Overall design
2.1 Process action decomposition
The process action refers to the method of transforming raw materials into final products through a series of organized and standardized steps during the production or manufacturing process. For the dual ultrasonic-assisted diamond wire saw cutting device, the entire cutting process can be broken down into five distinct actions. The specific requirements for each of these process actions are outlined as follows.
(1) Device preparation
Before starting the device, check the various technical indicators of the equipment and replace any necessary special fixtures along with the diamond wire saw model used.
(2) Workpiece installation
Once the device is ready, install the workpiece on the appropriate special fixture to ensure that it can be accurately positioned and reliably clamped during the cutting process.
(3) Start the ultrasonic auxiliary equipment
Once the workpiece is installed, activate the ultrasonic auxiliary equipment for both the wire saw and the workpiece. Verify that the ultrasonic auxiliary equipment generates effective vibration.
(4) Start the feed mechanism
Once the ultrasonic auxiliary equipment is functioning properly, set the processing parameters via the control panel, start the CNC program, and then perform the dual ultrasonic-assisted diamond wire saw cutting process on the workpiece.
(5) Processing completed
After the workpiece is cut, turn off the dual ultrasonic auxiliary equipment, reset the feed mechanism, turn off the main power of the equipment, and unload the workpiece.
2.2 The dual ultrasonic-assisted diamond wire saw cutting device can be divided into three subsystems based on the analysis of the processes and the functions performed during the cutting action. This classification is achieved using systematic analysis methods.
(1) Feed subsystem
In the reciprocating diamond wire saw cutting process, a crank slider mechanism is utilized to achieve the reciprocating motion of the wire saw along the Z-axis. The movement along the X and Y axes is facilitated by a horizontally positioned CNC bidirectional worktable. Additionally, a screw nut transmission mechanism drives the worktable to perform the feed motion.
(2) Ultrasonic vibration subsystem
Ultrasonic-assisted vibration is achieved through the use of dual ultrasonic vibrations. One vibration is applied to the cutting wire saw, enabling it to achieve ultrasonic oscillation. The other vibration is applied to the fixture that holds the CNC milled parts, allowing the workpiece to also experience ultrasonic vibrations.
(3) Frame subsystem
All movable parts of the device must be installed on a specific fixed foundation to complete the cutting process. Therefore, it is essential to design corresponding components with fixed functions, such as the bed, column, and support seat.
2.3 Determination of Technical Parameters
After careful consideration, a small diamond wire saw was selected as the cutting tool, featuring dual ultrasonic-assisted vibration. This solution combines the benefits of diamond wire saw cutting equipment with ultrasonic machining, while also providing the advantages of a compact machine tool with a small footprint. The finalized main technical parameters are presented in Table 1. The overall structure of the dual ultrasonic-assisted reciprocating wire saw cutting device is illustrated in Figure 2. The device primarily consists of the X-axis feed, Y-axis feed, Z-axis feed, wire saw ultrasonic vibration application, fixture ultrasonic vibration application, column, and bed.
03 Performance Analysis of Key Components
3.1 Static Analysis of the Support Frame
The ultrasonic vibration system for the wire saw must be installed on a support frame. This frame is essential as it supports the weight of the ultrasonic vibration device, the tension of the wire saw, and the cutting forces involved. Consequently, a finite element static analysis of this crucial component is necessary to ensure that the designed support frame meets the required performance standards. The support frame is constructed from Q235D steel, and the main material parameters are detailed in Table 2.
The support frame is meshed and boundary conditions and loads are added. The total number of elements is 16891 and the total number of nodes is 28793. The mesh division is shown in Figure 3.
Static analysis revealed the equivalent stress contour of the support frame, as illustrated in Figure 4. This figure indicates that the maximum equivalent stress for the support frame is 33.63 MPa, which is significantly lower than the yield strength of Q235D material. Therefore, it meets the strength design requirements. Additionally, the deformation contour for the support frame is presented in Figure 5, showing that the maximum deformation is 1.589 mm. This value is relatively small and also meets the design specifications.
3.2 Modal analysis of ultrasonic horn
(1) Design and calculation of composite horn
The diamond wire saw requires a large amplitude for effective operation, which necessitates that the designed horn achieve the highest possible vibration velocity or displacement amplitude. To accomplish this, both the shape factor and amplification coefficient of the horn should be maximized. However, theoretical analysis indicates that in a single horn, there often exists a trade-off between the shape factor and the amplification coefficient, making it challenging to optimize both simultaneously.
To address this issue, this paper proposes the design of a composite horn aimed at enhancing output performance. The stepped composite horn features a combination of exponential, conical, and catenary transition sections, optimizing performance while also considering the complexities of design calculations and manufacturing.
The designed composite horn includes a stepped configuration with a conical transition section. By applying the theoretical calculation formulas specific to stepped horns with conical transition sections and taking various influencing factors into account, the design parameters were substituted into the relevant formulas. The main characteristic parameters of the composite horn developed in this study are presented in Table 3.
The calculated dimensions of the composite horn are shown in Figure 6. Here, according to the relevant formula for the axial distribution of displacement, the theoretical displacement distribution curve of the composite horn drawn using MATLAB software is shown in Figure 7.
(2) Modal Analysis of Composite Amplitude Transformer
The amplitude transformer described in this paper is constructed from 45 steel, with its material parameters outlined in Table 4. For the meshing process, we employed the volume sweep method to generate volume elements, as illustrated in Figure 8. Prior to conducting the modal analysis, we specified the analysis type as modal analysis and selected the subspace method for modal extraction. The frequency range for modal extraction was set between 18 kHz and 22 kHz, and we aimed to extract a total of six modes. In this modal analysis, the only effective load applied was the zero displacement constraint.
After conducting a modal analysis on the designed composite horn, we obtained its natural frequency during longitudinal vibration. The longitudinal vibration modal diagram and the axial relative displacement distribution curve are illustrated in Figures 9 and 10. By comparing the results from the theoretical design calculations with those from the finite element modal analysis, it is evident that the finite element simulation results are largely consistent with the theoretical calculations. This comparative analysis further confirms the reliability and advantages of using the finite element method in the design of ultrasonic horns.
To further investigate the vibration characteristics of the designed composite horn after installing a diamond wire saw, a finite element modal analysis was conducted. The simulation results are presented in Figures 11 and 12. As demonstrated in these figures, the longitudinal vibration modes and axial relative displacement distributions of the composite horn with the diamond wire saw are very similar to those without it. This indicates that the designed composite horn can effectively transmit ultrasonic vibrations to the diamond wire saw, enabling it to achieve high-frequency longitudinal vibrations and meet the design requirements.
To validate the theoretical and simulation results discussed earlier, this paper includes experimental measurements of the displacement amplitudes at both the input and output ends of the designed composite horn. The input displacement amplitude was relatively small; therefore, an accelerometer was employed for indirect measurement. This choice reduced the stringent requirements for the accelerometer’s measurement range and allowed for real-time monitoring of the horn’s vibration characteristics.
In contrast, the output displacement amplitude was considerably larger, so a micrometer was utilized for direct measurement. Given that the micrometer is a precision instrument with a minimum scale of 1 μm, it can accurately measure the displacement amplitude at the output end of the fully composite horn.
Measuring the input displacement amplitude indirectly using an accelerometer is more complex, necessitating the establishment of a corresponding test system. The block diagram of the accelerometer test system is shown in Figure 13. The test equipment primarily includes a YD10D piezoelectric accelerometer, a YE5850 charge amplifier, a PDS5022S portable color digital storage oscilloscope, and a peach-shaped micrometer.
Table 5 presents a comparison of the theoretical, simulation, and experimental results for the composite horn both with and without diamond wire saws. The data indicates that the amplification factor for the composite horn equipped with diamond wire saws remains nearly the same as that of the horn without them. Additionally, the longitudinal vibration frequency is slightly lower in the presence of diamond wire saws.
When comparing the relative errors between the experimental longitudinal vibration frequencies of the composite horn with and without diamond wire saws and the theoretical values, it is observed that while the longitudinal vibration frequency increases, the relative errors are only 0.95% and 0.85%, respectively. Thus, the designed composite horn effectively meets the cutting requirements for ultrasonically assisted diamond wire saws.
04 Conclusion
To address the challenges of low cutting quality, inefficiency, and short wire life associated with existing reciprocating diamond wire saws, a new dual-ultrasonic-assisted diamond wire saw cutting device has been designed. This innovative device simultaneously applies ultrasonic vibrations to both the wire saw and the metal fabrication parts.
Using a system analysis approach, the device has been divided into three subsystems: feed, ultrasonic vibration, and frame. The overall design and key technical parameters have been established. A finite element static analysis of the support frame, which is a critical component, confirmed that both the equivalent stress and deformation are within the design specifications.
Additionally, a composite horn was designed and calculated based on theoretical formulas, followed by a finite element modal analysis. This analysis validated the rationality and feasibility of the theoretically designed vibration modes and resonant frequencies. Modal analysis was also conducted for the composite horn in conjunction with the diamond wire saw.
The simulated and experimental amplification coefficients remained virtually unchanged when compared to the composite horn without the diamond wire saw, although the longitudinal vibration frequency exhibited a reduction. The relative error between the experimental and theoretical values was recorded at 0.85%, further confirming that the designed composite horn meets the required specifications.
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