CN102653031B - Laser drive combined flyer forming method and device thereof - Google Patents

Abstract

The invention relates to the technical field of mechanical manufacturing, in particular to a laser-driven combined flyer forming method and device thereof. This invention proposes for the first time that the pulsed laser is used to drive the energy-carrying flyer to move at a high speed. After the energy-carrying flyer flies for a certain distance, it collides with the stationary forming flyer. With the ultra-high speed of the energy-carrying flyer, the formed flyer flies a certain distance and collides with the workpiece, generating a high-pressure shock wave on the collision interface, which propagates to the inside of the workpiece material, causing the material to produce ultra-fast plastic deformation in the micro-mold, thereby realizing Precise shaping of workpieces. The invention can significantly increase the speed of forming flyers under the existing experimental conditions, thereby enhancing the forming ability of laser-driven flyer technology, and is suitable for precision forming of materials that require high surface quality or are difficult to form, and can be used for micro devices Manufacturing and other fields.

Description

A laser-driven composite flyer forming method and device thereof

technical field

The invention belongs to the technical field of micro-electro-mechanical system manufacturing by laser processing, and particularly refers to a laser-driven composite flyer forming method and its device, which can accurately copy the micro-features on the micro-mold to the workpiece, and is suitable for micro-scale or difficult-to-form by conventional methods. Micro-volume forming of complex workpieces that cannot be formed.

Background technique

With the development of modern science and technology and the increasing demand for micro-parts and micro-devices, miniaturization has become an important direction for the development of contemporary science and technology; because micro-forming devices are generally small in size, relatively complex in internal structure, and require high precision parts, The current micro-forming device has problems such as high difficulty in processing operation and low processing efficiency, which makes it difficult for traditional forming methods and devices to meet the requirements of modern micro-part processing; at the same time, quasi-static plastic micro-forming is affected by the scale effect, and the material forming ability is reduced. , it is difficult to meet the processing of some difficult-to-form materials such as high hardness and high brittleness, so that it is subject to many restrictions in industrial production; therefore, scholars at home and abroad are actively looking for new micro-forming methods on the basis of traditional micro-forming. The advanced laser processing technology provides a good research basis for us to solve this problem; due to the good quality of laser processing and high processing accuracy, compared with traditional processing methods, the processing quality and efficiency are significantly improved, and laser processing technology is increasingly widely used in Processing of tiny parts.

Laser-driven flyer forming technology is a new type of high-pressure high-strain rate forming technology, that is, the laser-driven flyer loading method replaces the direct impact of the laser, converts laser energy into kinetic energy of the flyer, and uses the laser to drive the flyer to move at high speed. The moving flyer, as the carrier of laser energy, collides with the workpiece material after flying for a certain distance, and generates high-pressure shock waves on the collision interface to cause ultra-fast plastic deformation of the material in the micro-mold, thereby realizing the precise forming of the workpiece in the micro-mold; Compared with traditional high-speed driving methods such as gas cannon, detonation drive, and electromagnetic drive, the laser-driven flyer technology can significantly increase the speed of the flyer, thereby generating an impact pressure of the TPa level; the laser-driven flyer forming technology With high repeatability and simple device, it is a low-cost, high-efficiency new laser micromachining technology, which has great theoretical research and potential application value in many research fields involved.

Flyer speed is a main performance index in laser-driven flyer technology, which directly reflects the utilization rate of laser energy and dynamic loading performance of flyer, and is the research focus of laser-driven flyer forming technology; however, the current laser-driven flyer forming technology Due to the limitations of laser performance, flyer material selection and preparation process, etc., the energy coupling efficiency of the flyer is low, and the driving speed of the flyer is low, which leads to the low forming ability of the laser-driven flyer technology; such as the invention patent application No. 200810023264.3 Chinese patent a kind of laser shock micro-volume forming method and device for micro-device and application No. 201010505882.9 Chinese patent a kind of laser indirect composite microplastic forming device and method, in order to improve the driving speed of flyer, both A method of using water or silicone oil to adhere the constrained layer and the flyer to prepare the flyer target is proposed. Due to the adhesion of the coating material, this method is prone to problems such as weak or uneven bonding, resulting in Plasma leakage occurs during the impact process, which leads to a decrease in the energy coupling efficiency of the flyer. The flyer driven out by the laser cannot reach a high speed, which reduces the impact pressure generated by the collision between the flyer and the workpiece, thus causing the laser to drive the flyer. Compared with the laser-driven flyer forming method proposed in the above patents, the laser-driven composite flyer forming method described in the present invention can better solve the problem of driving flyer under the existing experimental conditions. It is a low-cost, high-efficiency new laser micromachining technology to solve the problems of low sheet speed and poor forming ability.

Contents of the invention

The present invention is mainly aimed at the outstanding problem that the driving speed of the flying piece is low during the forming process of the laser-driven flying piece, which leads to the low forming ability of the laser-driven flying piece technology; in order to solve this problem, the existing experimental device and related Due to the ultra-high-speed launch capability of the technology, the present invention proposes for the first time the combined flyer forming method in the laser-driven flyer forming technology.

The device of the present invention is mainly composed of a laser loading system, a forming system and a control system; the laser loading system is composed of a nanosecond laser, a reflector, and a focusing lens, and the nanosecond laser is equipped with an indicating light system; Sample device, clamp body, three-dimensional mobile platform and L-shaped base; the control system is composed of three-dimensional mobile platform controller, computer, and laser controller.

In the forming system, the bottom is the L-shaped base, the three-dimensional mobile platform is placed on the L-shaped base, and the sample device, clamp body and combined flyer device are placed on the top of the three-dimensional mobile platform from bottom to top; the micro-mold is located at the lower part of the sample device , the positioning and clamping are carried out through the clamp body, and the workpiece is placed on the micro-mold; the combined flyer device is composed of a forming system and an impact system. The flyer and the buffer layer are bonded by distilled water or silicone oil; the impact system is located above the forming system as a whole, and from bottom to top are the impact tube, energy-carrying flyer and constraining layer, and the energy-carrying flyer and constraining layer are bonded with distilled water ; The forming tube adopts WAl1 tungsten alloy as the tube wall material, the buffer layer material is selected polypropylene plastics, the constraining layer adopts K9 glass, and the energy-carrying flyer and the forming flyer adopt aluminum foil; 1.5 times.

The method of the present invention adopts the combination flyer device in the laser-driven flyer forming technology, utilizes the energy-carrying flyer driven to a high-speed mass m1 to hit the forming flyer whose mass is m2, and the ratio of m1 and m2 is based on The speed required to form the flyer is adjusted, generally between 6~30:1; the energy-carrying flyer flies a certain distance in the impact tube and is accelerated to a larger speed value, the high-speed flying energy-carrying flyer and the buffer layer collision, the material of the buffer layer is dissociated or gasified after being compressed. Since the forming tube uses WAl1 tungsten alloy as the tube wall material, a strong compression wave or shock wave will be reflected from the upper end of the forming tube at this time, making the edge area of the forming tube The pressure is much higher than the pressure at the center, resulting in two-dimensional converging flow of the gas formed by the buffer layer material, and the energy at the edge is continuously converging toward the center, which drives the forming flyer to accelerate to an ultra-high speed; due to the formed flyer The diameter and mass of the flyer are smaller than that of the energy-carrying flyer. According to the speed gain relationship between the two flyers, the forming flyer can obtain an ultra-high speed 2 to 5 times higher than the energy-carrying flyer, so that after the forming flyer collides with the workpiece Stronger shock waves are generated on the collision interface, thereby enhancing the forming ability of the laser-driven flyer.

When the device of the present invention is working, the pulsed laser light emitted by the nanosecond laser acts on the upper surface of the energy-carrying flyer after passing through the first reflector, the second reflector, and the focusing lens, and ablates a part of the flyer to generate high-temperature and high-pressure plasma. The plasma continues to absorb the laser energy for a wide period of time, causing the plasma to expand and explode. Under the confinement of the confinement layer, the exploding plasma rapidly splashes toward the flying pieces, and its recoil force can form a strong shock wave to drive the remaining flying pieces forward. , during the duration of the laser pulse, the energy-carrying flyer will continuously absorb the laser energy, convert it into its own kinetic energy, and accelerate to fly forward; Flying for a certain distance in the direction of the sheet, the high-speed flying energy-carrying flyer collides with the buffer layer, and the material of the buffer layer is compressed and then dissociates or gasifies, and the formed gas undergoes a two-dimensional convergent flow, which then drives the formed flyer to move; according to the two The speed gain relationship between the flyers, the formed flyer can obtain a higher speed than the energy-carrying flyer, the formed flyer collides with the workpiece after flying a certain distance in the forming tube, and a high-pressure shock wave is generated on the collision interface, and the high-pressure shock wave Propagate to the inside of the workpiece, making the material produce ultra-fast plastic deformation in the micro-mold, so as to realize the precise shaping of the workpiece.

In order to verify the forming effect of the combined flyer proposed in this patent, the forming of the workpiece was observed through a set of comparative experiments; the comparative experiment used a Spitlight 2000 Nd:YAG laser with a pulse width of 8ns, a wavelength of 1064nm, and a confinement layer of ?40mm×1.76mm K9 glass, the test workpiece material is copper foil (thickness 20μm), the laser pulse energy is 1380mJ, and the defocus is -30cm; in the comparison test, a group adopts the laser-driven flyer forming technology as shown in Figure 3, and the flyer has a purity of 99.9% aluminum foil (thickness 17 μm), the length of the experimental flight cavity is 170 μm, and the constrained layer and the flyer are bonded with distilled water; The sheets are all made of aluminum foil with a purity of 99.9%, the thicknesses are 80 μm and 17 μm, the mass ratio is 8:1, the length of the impact tube is 220 μm, the length of the forming tube is 170 μm, and the buffer layer is made of polypropylene plastic with a thickness of 60 μm. The buffer layer is bonded with distilled water; Fig. 4 is a three-dimensional topographical figure of the formed workpiece of the prior art, and Fig. 5 is a three-dimensional topographical figure of the formed workpiece of the technical solution of the present invention; the maximum depth of deformation of the workpiece in Fig. 4 is 105.189μm, while the maximum deformation depth of the workpiece in Figure 5 is 161.342μm. The experimental results show that the forming effect of the combined flyer is far better than the current laser-driven flyer forming method.

Effect of the present invention:

1. When the energy-carrying flyer hits the forming flyer, because the mass of the forming flyer is smaller than the energy-carrying flyer, its speed is increased by 2 to 5 times compared with the energy-carrying flyer, thereby producing a supercharging effect. Using this If the ultra-high-speed formed flyer hits the workpiece, the ultra-high pressure of TPa level can be obtained; it can be seen that the ultra-high-speed flight of the formed flyer can be realized under the existing experimental conditions by using the laser-driven combined flyer method. The flying piece forming ability has been greatly improved, and it has the characteristics of low cost, simple process and high efficiency, and can be used for large-scale industrial promotion.

2. Due to the existence of the buffer layer when the energy-carrying flyer collides with the forming flyer, the uniform and non-impact loading of the energy-carrying flyer on the forming flyer is realized; the temperature rise of the forming flyer can be significantly reduced, effectively avoiding the traditional During the loading process of the laser-driven flyer, the ablation or melting of the flyer due to excessive temperature rise can better realize the "cold" and "fast" acceleration of the formed flyer, and at the same time improve the conversion efficiency of laser energy, which is effective It is beneficial to the improvement of the speed of the flyer and the improvement of the forming ability of the laser-driven flyer.

Description of drawings

Shown in Fig. 1 is the device schematic diagram of the laser-driven combination flyer forming method proposed according to the present invention;

Shown in Fig. 2 is the schematic diagram of the combined flying sheet device proposed according to the present invention;

Figure 3 is a schematic diagram of the flyer target system in the traditional laser-driven flyer forming process;

Fig. 4 is a three-dimensional topography diagram of a formed workpiece of the prior art;

Fig. 5 is a three-dimensional topography diagram of a formed workpiece adopting the technical solution of the present invention;

In the figure, 1. L-shaped base, 2. Three-dimensional mobile platform, 3. Clamp body, 4. Sample device, 5. Combined flyer device, 6. Focusing lens, 7. Second mirror, 8. First reflection Mirror, 9. Nanosecond laser, 10. Laser controller, 11. Computer, 12. Three-dimensional mobile platform control, 13. Constrained layer, 14. Energy-carrying flying sheet, 15. Shock tube, 16. Buffer layer, 17. Forming Flying piece, 18. Forming tube, 19. Workpiece, 20. Micro mold, 21. Flying piece, 22. Flying cavity.

Detailed ways

The details and working conditions of the technical solution proposed by the present invention will be described in detail below in conjunction with the accompanying drawings.

Fig. 1 is that the present invention carries out the schematic diagram of laser-driven combined flyer forming device; Laser controller 10 is connected with nanosecond laser 9 and computer 11 respectively, and computer 11 controls laser controller 10, and laser controller 10 sends the pulse to nanosecond laser 9 The laser parameters are adjusted; the laser light emitted by the nanosecond laser 9 is irradiated on the combined flyer device 5 through the first reflector 8, the second reflector 7 and the focusing lens 6; the clip body 3 is placed on the three-dimensional mobile platform 2 for Clamping and positioning the sample device 4, the combined flyer device 5 is pressed on the sample device 4; the three-dimensional mobile platform 2 is installed on the L-shaped base, the three-dimensional mobile platform controller 12 is connected with the three-dimensional mobile platform 2, and the three-dimensional mobile platform The displacement adjustment of 2 is regulated by a three-dimensional mobile platform controller 12 controlled by a computer 11.

Fig. 2 is the schematic diagram of the combined flyer device proposed by the present invention; the combined flyer device is composed of a constrained layer 13, an energy-carrying flyer 14, an impact tube 15, a buffer layer 16, a forming flyer 17 and a forming tube 18; the constrained layer adopts K9 Glass, the role is to limit the divergence of the explosive plasma and make it move towards the absorbing layer film and the workpiece, while ensuring that there is no obvious energy loss when the laser beam passes through, and distilled water or silicone oil is used to adhere between the constrained layer 13 and the energy-carrying flying piece 14 Prepare the energy-carrying flyer target together, the buffer layer 16 is made of polypropylene plastic, and the buffer layer 16 dissociates or gasifies after being compressed, which can reduce the temperature rise of the formed flyer during the collision process, and at the same time realize the energy-carrying flyer 14 The uniform and non-impact loading of the formed flying pieces 17 has a certain effect of heat insulation and shock absorption.

The specific process of implementing the technical solution is as follows:

(1) Design the micro-mold according to the forming requirements of the workpiece to be formed, and calculate the processing parameters such as laser energy, spot diameter, and defocus through the Gurney model of the laser-driven shock flyer movement.

(2) According to the actual situation of processing, adjust the height of the three-dimensional mobile platform 2 to facilitate the installation of the sample device 4, then clamp the sample device 4 in the clamp body 3, and press the combined flying piece device 5 on the sample On the device 4; then, turn on the laser controller 10 and the nanosecond laser 9, utilize the laser controller 10 to regulate and control the nanosecond laser 9 equipped with the indicating light to send a beam of indicating light, and the indicating light passes through the first reflecting mirror 8, the second reflecting The mirror 7 reaches the combined flying piece device 5 through the focusing lens 6, uses the three-dimensional mobile platform controller 12 to control the precise movement of the three-dimensional mobile platform 2, obtains the required spot area on the constrained layer 13, and then keeps the positions of each component fixed, and closes the indication Light.

(3) According to the processing requirements, the computer 11 calculates the parameters and sends the parameters to the laser controller 10. The laser controller 10 controls the nanosecond laser 9 to emit a pulsed laser with a certain energy and a certain pulse width, and the pulsed laser passes through the mirror 8 in turn. , the second reflector 7, passes through the confinement layer 13 to reach the energy-carrying flyer 14 after passing through the focusing lens 6, and the laser-driven energy-carrying flyer 14 passes through the impact tube 15 and collides with the buffer layer 16 at high speed. , the material of the buffer layer 16 is dissociated or gasified after being compressed. Since the forming tube 18 adopts WAl1 tungsten alloy with high impedance as the tube wall, a strong compression wave or shock wave will be reflected from the upper end of the forming tube at this time, making the forming tube 18 The pressure in the edge area is much higher than the pressure in the center, resulting in two-dimensional converging flow of the gas formed by the material of the buffer layer 16, and the energy at the edge is continuously converging toward the center, thereby driving the formed flying piece 17 to accelerate to an ultra-high speed; In the combined flyer device, the diameter and quality of the formed flyer 17 are smaller than the energy-carrying flyer 14, and according to the speed gain relationship between the two flyers, the forming flyer 17 obtains a higher speed than the energy-carrying flyer 14, The formed flyer 17 collides with the workpiece 19 after flying for a certain distance in the forming tube 18, and a high-pressure shock wave is generated on the collision interface, causing the workpiece 19 to produce ultra-fast plastic deformation in the micro-mold 20, thereby realizing the workpiece 19 in the micro-mold 20. precise shaping.

Claims (2)

1. A laser-driven combination flyer forming method, characterized in that: the pulsed laser light sent by the nanosecond laser acts on the upper surface of the energy-carrying flyer after the first reflector, the second reflector, and the focusing lens, and ablates a part of the flyer And generate high-temperature and high-pressure plasma, the plasma continues to absorb laser energy within the laser pulse width, causing the plasma to expand and explode. A strong shock wave is formed to drive the remaining flyers to move forward. During the duration of the laser pulse, the energy-carrying flyers will continuously absorb the laser energy, convert it into its own kinetic energy, and accelerate forward flight; when the incident laser pulse ends, the energy-carrying flyers will The flyer has already flown for a certain distance in the direction of the formed flyer in the impact tube, the high-speed flying energy-carrying flyer collides with the buffer layer, the material of the buffer layer is compressed and dissociated or gasified, and the formed gas undergoes two-dimensional convergent flow , and then drive the forming flyer to move; according to the speed gain relationship between the two flyers, the forming flyer can obtain a higher speed than the energy-carrying flyer, and the forming flyer collides with the workpiece after flying a certain distance in the forming tube, A high-pressure shock wave is generated on the collision interface, and the high-pressure shock wave propagates to the inside of the workpiece, causing the material to produce ultra-fast plastic deformation in the micro-mold, thereby realizing the precise forming of the workpiece; the forming tube uses WAl1 tungsten alloy as the tube wall material, and the buffer layer material Polypropylene plastic is selected, the length of the impacting tube is equal to 1-1.5 times the length of the forming tube, and the mass ratio of the energy-carrying flyer to the forming flyer is 6-30:1. 2. A laser-driven combined flyer forming device, consisting of a laser loading system, a forming system and a control system, is characterized in that: the forming system includes a combined flyer device; the combined flyer device consists of a forming system and an impact system The forming system consists of forming tube, forming flyer and buffer layer from bottom to top, and the forming flyer and buffer layer are bonded by distilled water or silicone oil; the impact system is located above the forming system as a whole, and the order from bottom to top is impact The tube, the energy-carrying flying piece and the constraining layer, the energy-carrying flying piece and the constraining layer are bonded with distilled water; the forming tube uses WAl1 tungsten alloy as the tube wall material, the buffer layer material is made of polypropylene plastic, and the length of the impacting tube is equal to the forming 1 to 1.5 times the length of the tube, and the mass ratio of the energy-carrying flyer to the formed flyer is 6-30:1.