A method for chip recovery in laser-helix milling combined hole making

Abstract

The present application relates to a kind of laser-helix milling compound hole cutting chip recycling method, belong to laser-helix milling compound hole technology field, specifically includes: workpiece is placed in closed vacuum box, after vacuumizing, inert gas is filled to form anaerobic environment;Electrostatic field is generated below workpiece during processing, and cutting chip and carbon smoke are adsorbed and fixed;Intermittent or after processing, electrostatic field is removed, and cutting chip block is under the action of gravity through cutting chip passage and falls into collection container.The present application can efficiently capture light micro-nano cutting chip under low-pressure inert gas environment, inhibit harmful dust diffusion from source, protect personnel health and machine tool equipment, realize cutting chip closed leak-free collection throughout.

Description

Technical Field

[0001] This invention belongs to the field of laser-spiral milling composite hole making technology, and particularly relates to a chip recovery method for laser-spiral milling composite hole making. Background Technology

[0002] Carbon fiber reinforced polymer (CFRP) composites, with their superior specific strength, specific stiffness, and excellent fatigue resistance, have become core structural materials in aerospace, high-end automotive manufacturing, and other fields. However, during precision machining (such as drilling and milling), especially when using advanced laser-assisted helical milling technology in an oxygen-free environment, a large amount of debris and dust ranging in size from micrometers to nanometers is generated. These debris are extremely lightweight, irregularly shaped, and easily electrostatically charged. Traditional chip collection mechanisms, such as mechanical chip removal relying on gravity and mechanical force, and air blowing using high-speed airflow for directional sweeping, lack sufficient capture power and cannot effectively overcome the inertia or electrostatic adsorption force of lightweight carbon fiber debris. Furthermore, CFRP debris has a low density and is easily dispersed and suspended under weak airflow or disturbance. Traditional methods can handle some larger particles under normal pressure, but under low pressure, the airflow power is insufficient, and the collection effect on fine micrometer-sized debris is greatly reduced. Even more worrying is the nanoscale carbon fiber dust generated during processing. These ultrafine particles have a strong suspending ability in the confined processing space and settle extremely slowly. They are easily inhaled by operators, penetrating deep into the lungs and even entering the bloodstream. Their potential carcinogenicity and risk of causing respiratory diseases such as pneumoconiosis pose a serious and long-term threat to the health of on-site personnel.

[0003] In the laser-spiral milling composite hole making process of CFRP components, there are two major challenges: (1) Health and environmental hazards: High-energy laser ablation of materials instantly generates high-temperature smoke, which contains extremely fine fiber fragments and ultrafine carbon particles. These submicron and even nano-sized particles have extremely strong suspension and inhalability. Once inhaled by operators, they can penetrate deep into the alveoli and even enter the blood circulation system, causing irritation and inflammation to the respiratory system. Long-term exposure also poses a potential carcinogenic risk, seriously threatening the health of personnel. Mechanical milling mainly produces micron-sized powdery chips. These chips are also lightweight and easily dispersed, and are easily inhaled into the lungs through breathing, leading to occupational diseases such as pneumoconiosis and polluting the processing environment. (2) Equipment damage risk: Once the powdery chips escape, they may invade the key precision moving parts of the machine tool (such as linear guides, ball screws, spindle bearings, etc.). These hard particles will cause abnormal wear of the parts, scratch the surface, block the lubrication channels, significantly reduce the motion accuracy, dynamic performance and service life of the machine tool, and increase maintenance costs and production downtime risks.

[0004] Therefore, in the high-efficiency and precision machining of carbon fiber composites in an oxygen-free environment, especially in advanced processes such as laser-assisted spiral milling, traditional chip and dust collection methods are completely inadequate. Thus, developing a novel, efficient, and directional chip collection technology that can overcome the limitations of low-pressure environments, efficiently capture lightweight micron-sized debris, and completely remove hazardous nanoparticles has become an urgent technical requirement for ensuring process feasibility, improving machining quality, and especially protecting the occupational health and safety of operators. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a chip recovery method for laser-spiral milling composite hole making, which solves the problem that micron-sized chips and nano-sized carbon soot particles are difficult to effectively recover in a low-pressure, oxygen-free environment during laser-spiral milling composite hole making of carbon fiber composite materials.

[0006] A method for chip recovery in laser-spiral milling composite hole making includes the following steps:

[0007] The workpiece is placed in a sealed vacuum chamber, and after evacuation, it is filled with inert gas to make the processing area an oxygen-free environment.

[0008] During the laser-spiral milling composite hole-making process, an electrostatic field is generated below the workpiece, which adsorbs and fixes the chips and carbon fumes generated during processing within the electrostatic field area.

[0009] During processing breaks or after processing is completed, the electrostatic field is released, allowing the adsorbed chip clumps to fall into the collection container through the chip channel under the action of gravity.

[0010] The inert gas is argon.

[0011] The electrostatic field is generated by an electrostatic chuck positioned below the workpiece, the electrostatic chuck having an adsorption surface with a V-groove structure.

[0012] During the processing, the chip channel entrance located on the electrostatic chuck is kept sealed by an electronically controlled switch to ensure a continuous electrostatic field; during processing breaks or after processing, the electronically controlled switch is turned on to open the chip channel.

[0013] The way to remove the electrostatic field is to cut off the power source that generates the electrostatic field or reduce the output voltage of the power source.

[0014] As the clumps of chips fall into the collection container, additional vibrations are applied to help them detach completely.

[0015] The collection container is an anti-static material collection bag, which is detachably and sealed to the outlet of the chip channel; when it is full, the collection bag is sealed and replaced under closed conditions.

[0016] The pressure range after vacuuming is 1 kPa to 10 kPa, and the pressure inside the chamber stabilizes at 20 kPa to 50 kPa after being filled with inert gas.

[0017] The voltage that generates the electrostatic field is adjustable, with an adjustment range of 5kV to 30kV.

[0018] The voltage is adjusted according to the particle size and concentration of chips and soot during processing: the voltage is increased when the amount of nano-sized soot produced increases, and the voltage is decreased when micron-sized particles are mainly produced.

[0019] By employing the above technical solution, the present invention has at least the following beneficial effects:

[0020] This invention utilizes the switching of working states of a V-shaped electrostatic chuck to collect carbon fiber composite material chips. The V-shaped electrostatic chuck exhibits exceptional capture capability for micron-nano-sized lightweight chips in a low-pressure / inert gas environment, overcoming the inefficiency of traditional negative pressure suction under low pressure. This invention provides immediate adsorption at the source, significantly reducing the diffusion of harmful dust and fumes into the operating environment and substantially lowering the risk of personnel inhalation. Simultaneously, it effectively removes powdery chips, preventing contamination, wear, and clogging of precision moving parts of machine tools, thus protecting equipment accuracy and lifespan. This invention achieves fully enclosed chip collection without secondary pollution; it features a simple structure, flexible operation, and high adjustability. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the connection of the chip recovery device used in the present invention;

[0022] Figure 2 This is a schematic diagram of the V-shaped electrostatic chuck in the chip recovery device used in this invention;

[0023] In the picture:

[0024] 1. Argon gas cylinder; 2. Workpiece; 3. Fixture; 4. Base; 5. Chip channel; 6. Chip collection bag; 7. High voltage power supply; 8. Conductive film; 9. V-shaped electrostatic chuck; 10. Vacuum pump; 11. Vacuum chamber; 12. Vacuum gauge; 13. Openable window; 14. Electrical control switch. Detailed Implementation

[0025] To better explain and facilitate understanding of the present invention, the technical solution and effects of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] like Figures 1-2As shown, a chip recovery device for laser-spiral milling composite hole making includes a sealed vacuum chamber 11. The side wall or top of the vacuum chamber 11 is provided with an openable window 13 for loading and unloading carbon fiber reinforced composite workpiece 2. Further, a clamp 3, which can be a conventional pressure plate, is installed inside the vacuum chamber 11 to position and clamp the workpiece 2 at a predetermined processing position. A vacuum pump 10 is connected to the outside of the vacuum chamber 11, and the suction port of the vacuum pump 10 is connected to the inside of the vacuum chamber 11 through a pipeline to evacuate the vacuum chamber 11 to a set low pressure state. Simultaneously, a vacuum gauge 12 is installed on the vacuum chamber 11, with its sensing end extending into the vacuum chamber 11 to monitor the air pressure value inside the vacuum chamber 11 in real time.

[0027] Inside the vacuum chamber 11, directly below the processing area of ​​the workpiece 2, a V-shaped electrostatic chuck 9 is installed. The V-shaped electrostatic chuck 9 consists of a base 4 and a conductive film 8 covering the upper surface of the base 4. The base 4 is made of an insulating material, such as ceramic or engineering plastic. The upper surface of the base 4 is machined with a V-shaped groove structure, meaning the entire chip-collecting surface is inclined to both sides along the centerline, forming a V-shaped cross-section. Furthermore, the conductive film 8 is made of a material with good conductivity and a certain degree of flexibility, such as conductive rubber, metal foil, or conductive cloth, and is tightly adhered to the upper surface of the base 4. A high-voltage power supply 7 is installed below the base 4. The output end of the high-voltage power supply 7 is electrically connected to the conductive film 8 via a wire. When the high-voltage power supply 7 is energized, a high voltage is applied to the conductive film 8, thereby forming a strong electrostatic field in the space near the surface of the V-shaped electrostatic chuck 9.

[0028] The V-shaped electrostatic chuck 9 has a chip channel 5 extending through the base 4 and the conductive film 8 at its central longitudinal position. An electronic control switch 14 is installed at the upper opening of the chip channel 5. The electronic control switch 14 can be either a solenoid valve or a conventional mechanical movable baffle. Different operating states of the electronic control switch 14 are used to adjust the opening and closing of the chip channel 5. Furthermore, the lower end of the chip channel 5 passes through the bottom of the vacuum chamber 11 and connects to a chip collection bag 6 located outside the vacuum chamber 11. The chip collection bag 6 is made of wear-resistant and anti-static material, such as an anti-static polyethylene film with added conductive carbon black or an airtight non-woven composite material. The chip collection bag 6 is sealed to the outlet of the chip channel 5 and is used to receive and encapsulate the chip clumps released from the V-shaped electrostatic chuck 9.

[0029] In addition, an argon gas tank 1 is installed on the outside of the vacuum chamber 11. The outlet of the argon gas tank 1 is connected to the inside of the vacuum chamber 11 through a gas supply pipeline, which is equipped with a switch valve and a flow regulating valve. The argon gas tank 1 stores high-purity argon gas, which is used to fill the vacuum chamber 11 with argon gas after the vacuum pump 10 evacuates the vacuum, so as to create an oxygen-free environment and assist electrostatic adsorption.

[0030] The chip recovery method for laser-spiral milling composite hole making based on the above-mentioned laser-spiral milling composite hole making chip recovery device specifically includes the following steps:

[0031] Step S1: Preparation and atmosphere setup before processing.

[0032] First, the operator places the carbon fiber reinforced composite material workpiece 2 into the vacuum chamber 11 through the openable window 13, and the clamp 3 positions and clamps the workpiece 2. After confirming that the workpiece 2 is stable, the openable window 13 is closed, so that the vacuum chamber 11 is in a sealed state.

[0033] The vacuum pump 10 is started to evacuate the interior of the vacuum chamber 11. The operator observes the reading on the vacuum gauge 12 to bring the interior of the vacuum chamber 11 to a set negative pressure state of -0.09 MPa to -0.1 MPa. The purpose of evacuation is to create a low-pressure environment in preparation for subsequent argon filling.

[0034] Once the vacuum chamber 11 reaches the predetermined low-pressure state, open the outlet valve of the argon tank 1 and slowly fill the vacuum chamber 11 with high-purity argon gas through the gas supply pipeline. Argon, as an inert protective gas, is used to maintain an oxygen-free environment to replace residual air, ensuring that the processing area, especially the laser-affected area, is in a stable and controllable oxygen-free atmosphere. This is not only a requirement for certain laser processes such as anti-oxidation and ablation, but also eliminates the potential risk of combustion and explosion of carbon fiber dust in an oxygen-rich environment. Simultaneously, argon gas can assist in electrostatic adsorption. Under specific low pressures, an argon environment helps optimize the distribution of the electrostatic field and adsorption efficiency. Compared to a complete vacuum, the presence of a suitable amount of gas molecules is more conducive to the charging and migration of micron / nano-sized particles. During the argon filling process, continuously monitor the vacuum gauge 12 to ensure that the gas pressure inside the chamber is stabilized within a range suitable for workpiece processing.

[0035] Step S2: Electrostatic adsorption during processing.

[0036] After completing the above atmosphere preparation, laser-spiral milling composite hole making is started. Simultaneously or before starting the process, the electronic switch 14 on the V-shaped electrostatic chuck 9 is kept in the off state, sealing the upper opening of the chip channel 5 and creating a continuous adsorption surface on the upper surface of the V-shaped electrostatic chuck 9. Simultaneously, the high-voltage power supply 7 is switched on, applying a high voltage (5kV~12kV) to the conductive film 8, which can be adjusted in stages according to the actual working conditions, creating a strong electrostatic field in the space near the surface of the V-shaped electrostatic chuck 9.

[0037] In the laser-spiral milling composite hole-making process, the high-energy laser ablates the material, instantly generating high-temperature smoke containing extremely fine fiber fragments and nano-sized ultrafine carbon particles; mechanical milling mainly produces micron-sized powdery chips. These chips and carbon soot particles are immediately polarized by the strong electrostatic field on the surface of the V-shaped electrostatic chuck 9. Due to the inherent conductivity of carbon fibers and the irregular shape and extremely light weight of the chips and soot particles, the polarization effect in the electrostatic field is significant. This electrostatic field effectively polarizes the micron / nano-sized lightweight carbon fiber fragments, dust, and soot particles, charging them and causing them to be strongly adsorbed onto the surface of the conductive film 8.

[0038] Throughout the machining process, with the electronic control switch 14 in the off state, the chip channel 5 is effectively blocked, ensuring the continuity and integrity of the electrostatic field on the upper surface of the V-shaped electrostatic chuck 9. All chips, dust, and carbon soot particles generated during machining are firmly adsorbed and fixed on the surface of the V-groove, effectively preventing their diffusion into the machining environment.

[0039] Step S3: Chip recovery during processing breaks or after processing ends.

[0040] Once the drilling of a single hole is completed or the entire batch of machining is finished, the machining system stops operating. At this point, the chip collection phase begins.

[0041] First, the high-voltage power supply 7 is cut off or the applied voltage of the conductive film 8 is reduced, significantly weakening the electrostatic adsorption force. At the same time, the control switch 14 is opened, fully exposing the upper opening of the chip channel 5.

[0042] Because the upper surface of the base 4 of the V-shaped electrostatic chuck 9 adopts a V-groove structure, after the electrostatic adsorption force is released, the chip clumps gathered in the V-groove are no longer bound by the adsorption force. Under the action of gravity, the chip clumps automatically fall off and slide down the inclined surfaces on both sides of the V-groove to the lowest point in the center. The chip clumps that have slid to the center continue to fall and are discharged downward through the chip channel 5.

[0043] To further ensure that the chip clumps can smoothly detach from the surface of the conductive film 8 and pass through the chip channel 5, an auxiliary vibration device is provided below or on the side of the base 4. This device applies high-frequency, low-amplitude vibration to the base 4 while simultaneously releasing electrostatic adsorption, causing the chip clumps adhering to the surface of the conductive film 8 to completely detach. In this embodiment, a piezoelectric ceramic vibrator is used for the auxiliary vibration. After passing through the chip channel 5, the chip clumps fall directly into the chip collection bag 6 located at the bottom outlet of the vacuum chamber 11. The chip collection bag 6 is made of anti-static material, which effectively prevents the chips from scattering again due to frictional charging inside the bag, ensuring that the chips are safely and leak-free sealed and stored.

[0044] Step S4: Replacement of chip collection bag and subsequent processing.

[0045] Once the chip collection bag 6 is full, the operator, ensuring the vacuum chamber 11 is under normal pressure or the machine is stopped, removes the chip collection bag 6 from the interface and immediately seals the bag opening with a sealing buckle or heat seal to ensure the chips are safely and leak-free. A new chip collection bag 6 is then installed for subsequent processing. After being sealed and packaged, the chips can be safely processed or recycled.

Claims

1. A method for chip recovery in laser-spiral milling composite hole making, characterized in that, Includes the following steps: The workpiece is placed in a sealed vacuum chamber, and after evacuation, it is filled with inert gas to make the processing area an oxygen-free environment. During the laser-spiral milling composite hole-making process, an electrostatic field is generated below the workpiece, which adsorbs and fixes the chips and carbon fumes generated during processing within the electrostatic field area. During processing breaks or after completion, the electrostatic field is released, allowing the adsorbed chip clumps to fall into the collection container through the chip channel under the influence of gravity.

2. The chip recovery method for laser-spiral milling composite hole making according to claim 1, characterized in that, The inert gas is argon.

3. The chip recovery method for laser-spiral milling composite hole making according to claim 1, characterized in that, The electrostatic field is generated by an electrostatic chuck positioned below the workpiece, the electrostatic chuck having an adsorption surface with a V-groove structure.

4. The chip recovery method for laser-spiral milling composite hole making according to claim 3, characterized in that, During the processing, the chip channel entrance located on the electrostatic chuck is kept sealed by an electronically controlled switch to ensure a continuous electrostatic field; during processing breaks or after processing, the electronically controlled switch is turned on to open the chip channel.

5. The chip recovery method for laser-spiral milling composite hole making according to claim 1, characterized in that, The way to remove the electrostatic field is to cut off the power source that generates the electrostatic field or reduce the output voltage of the power source.

6. The chip recovery method for laser-spiral milling composite hole making according to claim 1, characterized in that, As the clumps of chips fall into the collection container, additional vibrations are applied to help them detach completely.

7. The chip recovery method for laser-spiral milling composite hole making according to claim 1, characterized in that, The collection container is an anti-static material collection bag, which is detachably and sealed to the outlet of the chip channel; when it is full, the collection bag is sealed and replaced under closed conditions.

8. The chip recovery method for laser-spiral milling composite hole making according to claim 1, characterized in that, The pressure range after vacuuming is 1 kPa to 10 kPa, and the pressure inside the chamber stabilizes at 20 kPa to 50 kPa after being filled with inert gas.

9. The chip recovery method for laser-spiral milling composite hole making according to claim 1, characterized in that, The voltage that generates the electrostatic field is adjustable, with an adjustment range of 5kV to 30kV.

10. A method for chip recovery in laser-spiral milling composite hole making according to claim 9, characterized in that, The voltage is adjusted according to the particle size and concentration of chips and soot during processing: the voltage is increased when the amount of nano-sized soot produced increases, and the voltage is decreased when micron-sized particles are mainly produced.

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