An ultrasonic-assisted low-temperature milling method for avoiding defects in rock wool fiber drawing

Abstract

The application provides an ultrasonic-assisted low-temperature milling method for avoiding defects in rock wool fiber drawing, and relates to the technical field of rock wool fiber processing, and comprises the following steps: raw material pretreatment, crushing and uniformly mixing rock wool raw materials, and then melting the rock wool raw materials into a rock wool melt; ultrasonic-assisted milling forming, using a mode-switchable piezoelectric ultrasonic transducer to drive a milling tool to generate high-frequency ultrasonic vibration, and applying the ultrasonic vibration to the contact interface between the milling tool and the rock wool melt; through the dynamic regulation and control mechanism of ultrasonic vibration-assisted fiber forming, the application utilizes high-frequency micro-impact to break the particles that are not completely melted in the melt, reduces the generation of slag balls, improves the flowability of the melt, controls the fiber diameter deviation within ±0.2 μm, the average fiber diameter meets the relevant standard requirement of ≤7 μm, significantly improves the forming uniformity and flexibility of the fiber, reduces the thermal conductivity of the fiber, improves the heat preservation performance, and solves the problem of substandard fiber quality in the traditional process.

Description

Technical Field

[0001] This invention relates to the field of rock wool fiber processing technology, and in particular to an ultrasonic-assisted low-temperature milling method for avoiding rock wool fiber filamentation defects. Background Technology

[0002] Rock wool fiber, as a high-performance fireproof and thermal insulation material, is widely used in building energy conservation and industrial insulation. Its performance directly affects building energy efficiency and fire safety. Currently, the mainstream processing technology for rock wool fiber is centrifugal drawing. This process involves melting rock wool raw materials and then using a high-speed rotating centrifugal roller to throw the melt out, forming continuous rock wool fibers. These fibers are then further cured and cut to obtain the finished product. Centrifugal drawing has the advantages of high production efficiency and large-scale production, making it the most widely used rock wool fiber processing method in current industrial production. Its core lies in using centrifugal force to stretch and shape the melt, ultimately obtaining the required fiber morphology and properties.

[0003] However, in existing centrifugal drawing processes, stress concentration is prominent during fiber forming. The uneven effect of centrifugal force leads to significant fiber diameter deviations, typically exceeding ±0.5μm. Furthermore, incompletely melted particles in the melt are difficult to break, easily generating a large number of slag balls. The slag ball content often exceeds the relevant standard limit of 10%, reducing the fiber's flexibility and thermal insulation performance. The high coefficient of friction between the melt and the drawing equipment interface results in excessive tensile and shear stress on the fibers, easily causing breakage and uneven length, leading to poor fiber length uniformity. Simultaneously, the traditional continuous cutting mode easily causes fibers to be elongated and pulled out, resulting in surface defects. Rock wool materials exhibit anisotropic fiber arrangement characteristics. Existing processes use fixed processing parameters, which cannot be dynamically adjusted according to changes in fiber orientation, resulting in high surface roughness (Ra typically greater than 4.8μm) and a tendency for burrs, delamination, and other defects. Additionally, the fiber tensile strength is difficult to meet the relevant standard requirement of ≥7.5kPa, affecting the overall performance and service life of the product. Therefore, this invention proposes an ultrasonic-assisted cryogenic milling method to avoid rock wool fiber drawing defects and solve the problems existing in the prior art. Summary of the Invention

[0004] To address the aforementioned problems, this invention proposes an ultrasonic-assisted cryogenic milling method to avoid rock wool fiber filament defects. This method utilizes a dynamic control mechanism of ultrasonic vibration-assisted fiber forming, employing high-frequency micro-impact to break up incompletely molten particles in the melt, reducing slag ball formation, improving melt fluidity, controlling fiber diameter deviation within ±0.2μm, and ensuring the average fiber diameter meets the relevant standard requirement of ≤7μm. This significantly improves fiber forming uniformity and flexibility, while simultaneously reducing the fiber thermal conductivity and enhancing insulation performance, thus solving the problem of substandard fiber quality in traditional processes.

[0005] To achieve the objective of this invention, the invention is implemented through the following technical solution: an ultrasonic-assisted cryogenic milling method for avoiding rock wool fiber filament pulling defects, comprising the following steps:

[0006] Raw material pretreatment involves crushing and mixing rock wool raw materials evenly before melting them into rock wool melt.

[0007] Ultrasonic-assisted milling forming uses a mode-switchable piezoelectric ultrasonic transducer to drive the milling cutter to generate high-frequency ultrasonic vibration, which is then applied to the contact interface between the milling cutter and the rock wool melt to achieve a periodic instantaneous contact cutting mode.

[0008] Ultrasonic-low temperature spatiotemporal synergistic chip breaking involves simultaneously spraying low-temperature cooling medium into the milling area to cool the rock wool fibers below the brittle transition temperature, combined with ultrasonic high-frequency micro-impact to achieve a novel chip breaking process.

[0009] Adaptive parameter control: The processing parameters are monitored in real time through the sensing system, and a closed-loop feedback system is constructed to dynamically adjust the ultrasonic vibration, low temperature cooling and milling feed parameters.

[0010] Post-processing involves cooling and curing the shaped fibers, cutting them, and removing dust to obtain the finished product.

[0011] Further improvements are made in the following aspects: In the raw material pretreatment, the rock wool raw material is crushed to a particle size of ≤6mm, the melting temperature is 1450-1550℃, the melt viscosity is controlled at 800-1400mPa·s, the mass ratio of SiO2+Al2O3 to CaO+MgO in the raw material is ≥1.6, and the melt is controlled to be free of obvious agglomeration.

[0012] Further improvements are made in the following aspects: In the ultrasonic-assisted milling forming process, the ultrasonic vibration frequency is 20-38kHz and the amplitude is 5-20μm. The piezoelectric ultrasonic transducer enables flexible switching between axial vibration, torsional vibration, and longitudinal bending coupled vibration. The tool vibration trajectory is changed by adjusting the voltage amplitude of the dual-frequency composite excitation signal. The periodic instantaneous contact mode is cutting-detachment-re-cutting, with a cutting time of 15-25μs and a detachment time of 10-15μs. The high-frequency micro-impact generated by ultrasonic vibration breaks up the incompletely melted particles in the melt, controlling the slag ball content to ≤8%.

[0013] Further improvements are made in that the piezoelectric ultrasonic transducer adopts a sandwich structure, and achieves vibration mode switching through modular design and modal optimization. During operation, the energy conversion is stable, and the vibration amplitude error is controlled to be ≤±0.5μm.

[0014] Further improvements are made in the following aspects: In the ultrasonic-low temperature spatiotemporal synergistic chip breaking process, the low-temperature cooling medium is liquid nitrogen or a mixture of liquid nitrogen and low-temperature inert gas, with a volume ratio of liquid nitrogen to inert gas of 3:1. The cooling medium injection pressure is 0.25-0.4MPa, the injection direction is at an angle of 30-60° to the milling tool axis, the cooling temperature is -20℃ to -40℃, and the novel chip breaking mode is impact-induced microcracks + brittle instantaneous fracture, controlling the chip length to be 4-9mm.

[0015] Further improvements are made in the adaptive parameter control, where the sensing system employs an embedded fiber optic sensing system and a cutting force sensor to monitor the temperature gradient, vibration response spectrum, and cutting force in the milling area in real time. The closed-loop feedback system is a three-parameter closed-loop feedback system based on fiber orientation, cutting force, and temperature. The parameter mapping relationship is established based on a rock wool fiber density distribution model, with the rock wool fiber density ranging from 0.03 to 0.12 g / cm³. 3 .

[0016] Further improvements are made in the following aspects: The dynamically adjustable parameters include ultrasonic frequency, cryogenic cooling medium flow rate, and milling feed rate. The ultrasonic frequency adjustment range is 25-38kHz, the cryogenic cooling medium flow rate adjustment range is 0.5-2.0L / min, and the milling feed rate adjustment range is 50-150mm / min. Through parameter adjustment, the surface roughness Ra of the machined surface is stably controlled at ≤1.6μm.

[0017] A further improvement is made in that the adaptive parameter control adopts an adaptive algorithm, the formula of which is:

[0018] F=k1×f+k2×Q+k3×v-k4×ρ-k5×ΔT,

[0019] Where: F is the milling cutting force, N; k1, k2, k3, k4, k5 are correction coefficients, k,1=0.8-1.2, k2=0.5-0.7, k3=0.3-0.5, k4=1.5-2.0, k5=0.1-0.2; f is the ultrasonic frequency, kHz; Q is the flow rate of the cryogenic cooling medium, L / min; v is the milling feed rate, mm / min; ρ is the density of rock wool fiber, g / cm³; ΔT is the temperature gradient of the milling area, ℃. The theoretical cutting force is calculated using this formula, compared with the actual monitored cutting force, and the parameters are dynamically adjusted to ensure stable machining.

[0020] Further improvements are made in the following aspects: In the post-processing, the cooling method adopts natural cooling, forced air cooling, or a combination of both, with a cooling time of 25-35 minutes, cooling to room temperature of 20-25℃, and a cutting length of 800-1200mm. After dust removal treatment, the finished fibers are controlled to be free of visible pull-out, burrs, or delamination defects.

[0021] Further improvements include: in the post-processing, the cooling process is divided into three stages to gradually reduce the temperature to room temperature. The first stage cools the temperature to 100-120℃ at a rate of 5-8℃ / min, the second stage cools the temperature to 40-50℃ at a rate of 3-5℃ / min, and the third stage allows the temperature to cool naturally to room temperature. After cooling and solidification, the product is precisely cut, with laser positioning assistance used during the cutting process. The dust removal process uses a combination of negative pressure adsorption and electrostatic dust removal. First, surface dust is removed by negative pressure adsorption, and then micro-dust impurities attached to the fiber surface are removed by electrostatic dust removal. After the post-processing is completed, the finished product needs to be sampled and tested in batches. After passing the test, the product is put into storage. The test includes at least fiber diameter uniformity, surface defects, and mechanical properties.

[0022] The beneficial effects of this invention are as follows:

[0023] 1. This invention utilizes a dynamic control mechanism for ultrasonic vibration-assisted fiber forming, employing high-frequency micro-impact to break up incompletely molten particles in the melt, reducing slag ball formation, improving melt fluidity, controlling fiber diameter deviation within ±0.2μm, and ensuring the average fiber diameter meets the relevant standard requirement of ≤7μm. This significantly improves fiber forming uniformity and flexibility, while simultaneously reducing fiber thermal conductivity and enhancing insulation performance, thus solving the problem of substandard fiber quality in traditional processes.

[0024] 2. This invention constructs a novel chip-breaking mode through the spatiotemporal synergistic mechanism of ultrasonic high-frequency impact and low-temperature embrittlement effect, fundamentally eliminating the mechanical conditions of fiber stretching and pulling out, avoiding fiber breakage due to stress concentration, improving fiber length uniformity by more than 30%, reducing surface defects such as burrs and delamination, improving fiber integrity, ensuring fiber tensile strength ≥10kPa, which is higher than the relevant standard requirements, and extending the service life of finished rock wool products.

[0025] 3. This invention constructs a three-parameter closed-loop feedback system by using an adaptive parameter control algorithm based on rock wool fiber orientation. This system dynamically adjusts processing parameters to keep the surface roughness Ra of the processed material stable at ≤1.6 μm, which is 67% better than conventional processes. It also eliminates visible fiber pull-out, burrs, or delamination defects. Furthermore, it is compatible with rock wool raw materials with different fiber orientations, improving the versatility and stability of the process, reducing the labor intensity of manual parameter adjustment, and increasing production efficiency and product qualification rate. Attached Figure Description

[0026] Figure 1 This is a flowchart of the present invention. Detailed Implementation

[0027] To enhance understanding of the present invention, the present invention will be further described in detail below with reference to embodiments. These embodiments are only used to explain the present invention and do not constitute a limitation on the scope of protection of the present invention.

[0028] Example 1

[0029] according to Figure 1 As shown in the figure, this embodiment proposes an ultrasonic-assisted cryogenic milling method to avoid rock wool fiber fraying defects, including the following steps:

[0030] Raw material pretreatment: Crush basalt, slag and other rock wool raw materials to a particle size ≤5mm, mix them evenly, and send them into a melting furnace to be heated to 1480℃ to melt them into a uniform rock wool melt. The melt viscosity is controlled at 1000-1200 mPa·s to ensure that the melt has no obvious agglomeration. Take samples to test the raw material composition to ensure that the mass ratio of SiO2+Al2O3 to CaO+MgO is ≥1.6, which meets the requirements of rock wool acidity coefficient.

[0031] Ultrasonic-assisted milling forming: Rock wool melt is transported to the milling area through a guide tube. A piezoelectric ultrasonic transducer with switchable modes is used to drive the milling cutter. The ultrasonic vibration frequency is set to 25kHz, the amplitude is 10μm, and the vibration mode is axial vibration. The ultrasonic vibration is applied to the contact interface between the milling cutter and the rock wool melt, which transforms the traditional continuous cutting into a periodic instantaneous contact mode of "cutting-detaching-recutting". The period of ultrasonic vibration is 40μs, of which the cutting time is 25μs and the detachment time is 15μs. The unmelted particles in the melt are broken by high-frequency micro-impact, which improves the fluidity of the melt.

[0032] Ultrasonic-Cryogenic Spatiotemporal Synergistic Chip Breaking: During milling, liquid nitrogen (a cryogenic cooling medium) is synchronously sprayed into the milling area through a nozzle. The liquid nitrogen flow rate is set to 1.0 L / min, the spray pressure is 0.3 MPa, and the spray direction is at a 45° angle to the axis of the milling tool. This rapidly cools the rock wool fiber to -30℃ (below the brittle transition temperature). Combined with the ultrasonic high-frequency micro-impact, a new chip breaking mode of "impact-induced micro-cracks + brittle instantaneous fracture" is achieved, controlling the chip length to 5-8 mm.

[0033] Adaptive parameter control: A closed-loop feedback system for fiber orientation, cutting force, and temperature is constructed by real-time monitoring of the temperature gradient (monitoring range 20-500℃, accuracy ±1℃) and vibration response spectrum in the milling area using an embedded fiber optic sensing system. This is combined with cutting force data collected by a cutting force sensor (monitoring range 0-500N, accuracy ±0.1N). The system is based on a rock wool fiber density distribution model (density 0.06 g / cm³). 3 Establish a mapping relationship, dynamically adjust the ultrasonic frequency, liquid nitrogen flow rate and feed rate. The initial feed rate is set to 100 mm / min, and fine-tuned in real time according to sensor data to ensure stable processing.

[0034] Post-processing: The processed rock wool fibers are sent into a cooling tunnel and cooled to room temperature (25°C) using a combination of natural cooling and forced air cooling for 30 minutes. Then, they are cut to a length of 1000 mm using a cutting device and surface dust is removed by a dust removal device to obtain the finished rock wool fibers.

[0035] The rock wool fibers processed in this embodiment were tested and found to have the following characteristics: fiber diameter deviation of ±0.15μm, average diameter of 6.2μm, slag ball content of 6.5%, fiber length uniformity improved by 35%, surface roughness Ra of 1.4μm, tensile strength of 11.2kPa, thermal conductivity of 0.042 W / (m·K), moisture absorption rate of 3.2%, and no visible fiber pull-out, burrs or delamination defects. All indicators met the standards.

[0036] Example 2

[0037] according to Figure 1 As shown in the figure, this embodiment proposes an ultrasonic-assisted cryogenic milling method to avoid rock wool fiber fraying defects, including the following steps:

[0038] Raw material pretreatment: Crush the rock wool raw material to a particle size ≤4mm, mix it evenly, and send it into a melting furnace to be heated to 1520℃ to melt it into a uniform rock wool melt. The melt viscosity is controlled at 800-1000 mPa·s to ensure that the melt has no obvious agglomeration. Take samples to test the raw material composition to ensure that the mass ratio of SiO2+Al2O3 to CaO+MgO is ≥1.6.

[0039] Ultrasonic-assisted milling forming: Rock wool melt is transported to the milling area through a guide tube. A piezoelectric ultrasonic transducer with switchable modes drives the milling cutter. The ultrasonic vibration frequency is set to 32kHz, the amplitude is 15μm, and the vibration mode is torsional vibration. The ultrasonic vibration is applied to the contact interface between the milling cutter and the rock wool melt to achieve a periodic instantaneous contact mode of "cutting-detaching-recutting". The ultrasonic vibration period is 31.25μs, of which the cutting time is 18μs and the detachment time is 13.25μs. The high-frequency micro-impact breaks up the incompletely melted particles in the melt, improving the melt fluidity.

[0040] Ultrasonic-Cryogenic Spatiotemporal Synergistic Chip Breaking: During milling, a mixed cooling medium of liquid nitrogen and cryogenic argon (volume ratio 3:1) is synchronously sprayed into the milling area. The flow rate of the mixed cooling medium is set to 1.5 L / min, the spray pressure is 0.4 MPa, and the spray direction is at a 60° angle to the axis of the milling tool. This rapidly cools the rock wool fiber to -25°C. Combined with the ultrasonic high-frequency micro-impact, a new chip breaking mode is achieved, controlling the chip breaking length to 6-9 mm.

[0041] Adaptive parameter control: The temperature gradient and vibration response spectrum of the milling area are monitored in real time by an embedded fiber optic sensing system. Combined with the cutting force data collected by the cutting force sensor, a three-parameter closed-loop feedback system of fiber orientation, cutting force and temperature is constructed. A mapping relationship is established based on the rock wool fiber density distribution model (density 0.09 g / cm³). The initial feed rate is set to 120 mm / min. The ultrasonic frequency (maintained at 30-34kHz), liquid nitrogen flow rate (1.3-1.7 L / min) and feed rate (110-130 mm / min) are dynamically adjusted to ensure machining stability.

[0042] Post-processing: The processed rock wool fibers are sent into a cooling tunnel and cooled to room temperature using forced air cooling for 25 minutes. They are then cut to a length of 1200 mm and subjected to dust removal and screening to obtain the finished rock wool fibers.

[0043] The rock wool fibers processed in this embodiment were tested and found to have the following characteristics: fiber diameter deviation of ±0.18μm, average diameter of 6.5μm, slag ball content of 7.2%, fiber length uniformity improved by 32%, surface roughness Ra of 1.5μm, tensile strength of 10.8kPa, thermal conductivity of 0.043 W / (m·K), moisture absorption rate of 3.5%, and no visible fiber pull-out, burrs or delamination defects. All indicators met the standards.

[0044] Example 3

[0045] according to Figure 1 As shown in the figure, this embodiment proposes an ultrasonic-assisted cryogenic milling method to avoid rock wool fiber fraying defects, including the following steps:

[0046] Raw material pretreatment: Crush the rock wool raw material to a particle size ≤6mm, mix it evenly, and send it into a melting furnace to be heated to 1450℃ to melt it into a uniform rock wool melt. The melt viscosity is controlled at 1200-1400 mPa·s to ensure that the melt has no obvious agglomeration. Take samples to test the raw material composition to ensure that the mass ratio of SiO2+Al2O3 to CaO+MgO is ≥1.6.

[0047] Ultrasonic-assisted milling forming: Rock wool melt is transported to the milling area through a guide tube. A piezoelectric ultrasonic transducer with switchable modes drives the milling cutter. The ultrasonic vibration frequency is set to 38kHz, the amplitude is 20μm, and the vibration mode is selected as longitudinal bending coupling vibration. The ultrasonic vibration is applied to the contact interface between the milling cutter and the rock wool melt to achieve a periodic instantaneous contact mode of "cutting-detaching-recutting". The ultrasonic vibration period is 26.3μs, of which the cutting time is 16μs and the detachment time is 10.3μs. The unmelted particles in the melt are broken by high-frequency micro-impact, which improves the fluidity of the melt.

[0048] Ultrasonic-Cryogenic Spatiotemporal Synergistic Chip Breaking: During the milling process, liquid nitrogen is synchronously sprayed into the milling area. The liquid nitrogen flow rate is set to 0.8 L / min, the spray pressure is 0.25 MPa, and the spray direction is at a 30° angle to the axis of the milling tool. This rapidly cools the rock wool fiber to -40°C. Combined with the ultrasonic high-frequency micro-impact, a new chip breaking mode is achieved, controlling the chip breaking length to 4-7 mm.

[0049] Adaptive parameter control: The temperature gradient and vibration response spectrum of the milling area are monitored in real time by an embedded fiber optic sensing system. Combined with the cutting force data collected by the cutting force sensor, a three-parameter closed-loop feedback system of fiber orientation, cutting force and temperature is constructed. A mapping relationship is established based on the rock wool fiber density distribution model (density 0.04 g / cm³). The initial feed rate is set to 80 mm / min. The ultrasonic frequency (36-38kHz), liquid nitrogen flow rate (0.7-0.9 L / min) and feed rate (70-90 mm / min) are dynamically adjusted to ensure machining stability.

[0050] Post-processing: The processed rock wool fibers are sent into a cooling tunnel and cooled to room temperature by natural cooling for 35 minutes. They are then cut to a length of 800 mm, and after dust removal and packaging, the finished rock wool fibers are obtained.

[0051] The rock wool fibers processed in this embodiment were tested and found to have the following characteristics: fiber diameter deviation of ±0.19μm, average diameter of 6.8μm, slag ball content of 7.8%, fiber length uniformity improved by 31%, surface roughness Ra of 1.55μm, tensile strength of 10.5kPa, thermal conductivity of 0.044 W / (m·K), moisture absorption rate of 3.8%, and no visible fiber pull-out, burrs or delamination defects. All indicators met the standards.

[0052] Comparative example (traditional centrifugal wire drawing process)

[0053] This comparative example uses a traditional centrifugal drawing process to process rock wool fibers. The specific steps are as follows:

[0054] Raw material pretreatment: Same as in Example 1, the rock wool raw material is crushed, mixed evenly, and sent into a melting furnace and heated to 1480°C to melt into a uniform rock wool melt;

[0055] Centrifugal drawing: The rock wool melt is conveyed to the centrifugal roller, and the melt is thrown out by the high-speed rotating centrifugal roller (speed of 3000r / min) to form continuous rock wool fibers;

[0056] Post-processing: Same as in Example 1, the fibers are cooled and solidified, cut, and dusted to obtain finished rock wool fibers.

[0057] The rock wool fibers obtained in this comparative example were tested and found to have the following characteristics: fiber diameter deviation of ±0.6μm, average diameter of 7.5μm, exceeding the national standard limit; slag ball content of 12.3%, exceeding the national standard limit of 10%; no significant improvement in fiber length uniformity; surface roughness Ra of 4.9μm; tensile strength of 6.8kPa, lower than the standard requirement of 7.5kPa; thermal conductivity of 0.048W / (m·K); moisture absorption rate of 5.2%; some fibers showed signs of breakage and pull-out; and the surface had obvious burrs and delamination defects. The product quality was far lower than that of the product in the embodiment of this invention.

[0058] Validation data:

[0059] The processing parameters and product performance of the examples and comparative examples were compared and tested. The test items were based on GB / T19686-2015 "Rock Wool and Slag Wool Insulation Products for Building" and related testing standards. The test results are shown in the table below:

[0060] Fiber diameter deviation μm ±0.15 ±0.18 ±0.19 ±0.6 ≤±0.5 average fiber diameter μm 6.2 6.5 6.8 7.5 ≤7 Slag ball content % 6.5 7.2 7.8 12.3 ≤10 Fiber length uniformity improvement rate % 35 32 31 0 - Machining surface roughness Ra μm 1.4 1.5 1.55 4.9 - tensile strength kPa 11.2 10.8 10.5 6.8 ≥7.5 Thermal conductivity (70℃±5℃) W / (m·K) 0.042 0.043 0.044 0.048 ≤0.046 Moisture absorption rate % 3.2 3.5 3.8 5.2 ≤5 Surface defects - none none none Burrs, delamination, and fiber pull-out No obvious defects

[0061] As can be seen from the above data, the rock wool fiber processed in the embodiments of the present invention has better performance indicators than the comparative example (traditional centrifugal drawing process) and meets all the standards. Among them, key indicators such as fiber diameter deviation, slag ball content, tensile strength, and thermal conductivity are significantly better than the standard requirements, which fully proves that the present invention can effectively avoid rock wool fiber drawing defects and improve product quality.

[0062] This ultrasonic-assisted cryogenic milling method, which avoids rock wool fiber fraying defects, utilizes a dynamic control mechanism of ultrasonic vibration-assisted fiber forming. High-frequency micro-impact breaks up incompletely molten particles in the melt, reducing slag ball formation, improving melt flowability, and controlling fiber diameter deviation within ±0.2μm. The average fiber diameter meets the relevant standard requirement of ≤7μm, significantly improving fiber forming uniformity and flexibility. Simultaneously, it reduces fiber thermal conductivity, enhancing insulation performance and solving the problem of substandard fiber quality in traditional processes. This invention constructs a novel chip-breaking mode through a spatiotemporal synergistic mechanism of ultrasonic high-frequency impact and cryogenic embrittlement effect, fundamentally eliminating the mechanical conditions for fiber stretching and pull-out. This prevents fiber breakage due to stress concentration, improving fiber length uniformity by more than 30%, while reducing surface defects such as burrs and delamination, enhancing fiber integrity, ensuring a fiber tensile strength ≥10kPa, exceeding relevant standard requirements, and extending the service life of finished rock wool products. This invention constructs a three-parameter closed-loop feedback system by using an adaptive parameter control algorithm based on rock wool fiber orientation. This system dynamically adjusts processing parameters to keep the surface roughness Ra of the processed material stable at ≤1.6 μm, which is 67% better than conventional processes. It also eliminates visible fiber pull-out, burrs, or delamination defects. Furthermore, it is adaptable to rock wool raw materials with different fiber orientations, improving the versatility and stability of the process, reducing the labor intensity of manual parameter adjustment, and increasing production efficiency and product qualification rate.

[0063] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. An ultrasonic-assisted cryogenic milling method for avoiding rock wool fiber fraying defects, characterized in that, Includes the following steps: Raw material pretreatment involves crushing and mixing rock wool raw materials evenly before melting them into rock wool melt. Ultrasonic-assisted milling forming uses a mode-switchable piezoelectric ultrasonic transducer to drive the milling cutter to generate high-frequency ultrasonic vibration, which is then applied to the contact interface between the milling cutter and the rock wool melt to achieve a periodic instantaneous contact cutting mode. Ultrasonic-low temperature spatiotemporal synergistic chip breaking involves simultaneously spraying low-temperature cooling medium into the milling area to cool the rock wool fibers below the brittle transition temperature, combined with ultrasonic high-frequency micro-impact to achieve a novel chip breaking process. Adaptive parameter control: The processing parameters are monitored in real time through the sensing system, and a closed-loop feedback system is constructed to dynamically adjust the ultrasonic vibration, low temperature cooling and milling feed parameters. Post-processing involves cooling and curing the shaped fibers, cutting them, and removing dust to obtain the finished product.

2. The ultrasonic-assisted cryogenic milling method for avoiding rock wool fiber filament defects according to claim 1, characterized in that: In the raw material pretreatment, the rock wool raw material is crushed to a particle size ≤6mm, the melting temperature is 1450-1550℃, the melt viscosity is controlled at 800-1400mPa·s, the mass ratio of SiO2+Al2O3 to CaO+MgO in the raw material is ≥1.6, and the melt is controlled to be free of obvious agglomeration.

3. The ultrasonic-assisted cryogenic milling method for avoiding rock wool fiber fraying defects according to claim 1, characterized in that: In the ultrasonic-assisted milling process, the ultrasonic vibration frequency is 20-38kHz and the amplitude is 5-20μm. The piezoelectric ultrasonic transducer enables flexible switching between axial vibration, torsional vibration, and longitudinal bending coupled vibration. The tool vibration trajectory is changed by adjusting the voltage amplitude of the dual-frequency composite excitation signal. The periodic instantaneous contact mode is cutting-detaching-re-cutting, with a cutting time of 15-25μs and a detachment time of 10-15μs. The high-frequency micro-impact generated by ultrasonic vibration breaks up the incompletely melted particles in the melt, controlling the slag ball content to ≤8%.

4. The ultrasonic-assisted cryogenic milling method for avoiding rock wool fiber fraying defects according to claim 3, characterized in that: The piezoelectric ultrasonic transducer adopts a sandwich structure and achieves vibration mode switching through modular design and modal optimization. During operation, the energy conversion is stable and the vibration amplitude error is controlled to be ≤±0.5μm.

5. The ultrasonic-assisted cryogenic milling method for avoiding rock wool fiber fraying defects according to claim 1, characterized in that: In the ultrasonic-cryo-spatial co-processed chip breaking, the cryogenic cooling medium is liquid nitrogen or a mixture of liquid nitrogen and cryogenic inert gas, with a volume ratio of liquid nitrogen to inert gas of 3:

1. The cooling medium injection pressure is 0.25-0.4 MPa, the injection direction is at an angle of 30-60° to the milling tool axis, and the cooling temperature is -20°C to -40°C. The novel chip breaking mode is impact-induced microcracks + brittle instantaneous fracture, and the chip length is controlled to be 4-9 mm.

6. The ultrasonic-assisted cryogenic milling method for avoiding rock wool fiber filament defects according to claim 1, characterized in that: In the adaptive parameter control, the sensing system employs an embedded fiber optic sensing system and a cutting force sensor to monitor the temperature gradient, vibration response spectrum, and cutting force in the milling area in real time. The closed-loop feedback system is a three-parameter closed-loop feedback system of fiber orientation, cutting force, and temperature. The parameter mapping relationship is established based on a rock wool fiber density distribution model, where the rock wool fiber density is 0.03-0.12 g / cm³. 3 .

7. The ultrasonic-assisted cryogenic milling method for avoiding rock wool fiber filament defects according to claim 6, characterized in that: The dynamically adjustable parameters include ultrasonic frequency, cryogenic cooling medium flow rate, and milling feed rate. The ultrasonic frequency adjustment range is 25-38kHz, the cryogenic cooling medium flow rate adjustment range is 0.5-2.0L / min, and the milling feed rate adjustment range is 50-150mm / min. By adjusting these parameters, the surface roughness Ra of the machined surface is stably controlled at ≤1.6μm.

8. The ultrasonic-assisted cryogenic milling method for avoiding rock wool fiber fraying defects according to claim 7, characterized in that: The adaptive parameter adjustment employs an adaptive algorithm, the formula of which is: F=k1×f+k2×Q+k3×v-k4×ρ-k5×ΔT, Where: F is the milling cutting force, N; k1, k2, k3, k4, k5 are correction coefficients, k,1=0.8-1.2, k2=0.5-0.7, k3=0.3-0.5, k4=1.5-2.0, k5=0.1-0.2; f is the ultrasonic frequency, kHz; Q is the flow rate of the low-temperature cooling medium, L / min; v is the milling feed rate, mm / min; ρ is the density of rock wool fiber, g / cm³; ΔT is the temperature gradient of the milling area, ℃; the theoretical cutting force is calculated by this formula, and compared with the actual monitored cutting force, and the parameters are dynamically adjusted to ensure stable machining.

9. The ultrasonic-assisted cryogenic milling method for avoiding rock wool fiber fraying defects according to claim 1, characterized in that: In the post-processing, the cooling method is natural cooling, forced air cooling, or a combination of both. The cooling time is 25-35 minutes, and the temperature is cooled to room temperature of 20-25℃. The cutting length is 800-1200mm. After dust removal treatment, the finished fiber is controlled to be free of visible pull-out, burr, or delamination defects.

10. The ultrasonic-assisted cryogenic milling method for avoiding rock wool fiber filament defects according to claim 9, characterized in that: In the post-processing, the cooling process is divided into three stages to gradually reduce the temperature to room temperature. The first stage cools the temperature to 100-120°C at a rate of 5-8°C / min, the second stage cools the temperature to 40-50°C at a rate of 3-5°C / min, and the third stage allows the temperature to cool naturally to room temperature. After cooling and solidification, the product is precisely cut using laser positioning assistance. The dust removal process combines negative pressure adsorption and electrostatic dust removal. First, negative pressure adsorption removes surface dust, and then electrostatic dust removal removes micro-dust impurities adhering to the fiber surface. After the post-processing is completed, the finished product is sampled and tested in batches. After passing the test, the product is put into storage. The test includes at least fiber diameter uniformity, surface defects, and mechanical properties.

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