Laser welding system and laser welding method based on plasma temperature control

Abstract

The application discloses a laser welding system and method based on plasma temperature control, which comprises a target vertical plate, an IR laser light source is arranged in front of a panel of the target vertical plate, a filter and a mirror in optical communication are arranged on both sides of the front of the panel of the target vertical plate, and a condenser in optical communication is arranged on the side of the filter away from the target vertical plate. The application can realize the output of high-intensity EUV laser by using a low-cost external IR laser light source, so that the energy conversion rate is improved, and the cost is reduced. The plasma is controlled by adjusting the laser incidence time difference, so that the interface effect is controlled, and finally, the balance between the interface effect and the cost is achieved, so that large-scale low-cost application is possible, and the high-precision operation of the industry is assisted.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of laser welding, and particularly relates to a laser welding system based on plasma temperature control. BACKGROUND

[0002] Laser welding is a kind of high-efficiency precision welding method using a high-energy-density laser beam as a heat source, and is one of important aspects of laser material processing technology application. It is mainly used for welding thin-wall materials and low-speed welding, and the welding process belongs to the heat conduction type, that is, the laser directly irradiates and heats the surface of a workpiece, the surface heat diffuses to the interior through heat conduction, and a specific molten pool is formed by melting the workpiece through control of parameters such as the width, energy, peak power and irradiation time of the laser pulse. Due to its unique advantages, it has been successfully applied to precision welding of micro and small parts.

[0003] At present, the ordinary light collecting equipment in laser welding not only has a complex structure, but also has an unsatisfactory reflectivity for the laser in the x-ray wavelength range, so in order to improve the focal point energy, most of the laboratory-scale desktop x-ray lasers adopt the way of increasing the energy intensity of the laser source, but the increase in the cost of the instrument is not proportional to the intensity gain effect. In addition, since the smoothness of the welding interface is related to the temperature of the irradiation surface, it is difficult to control the temperature of the irradiation surface using ordinary lasers, resulting in that the smoothness of the interface is difficult to meet the requirements. SUMMARY

[0004] The purpose of the present application is to provide a laser welding system based on plasma temperature control, which solves the problem that the existing laser welding method cannot simultaneously consider the interface effect and the cost.

[0005] Another purpose of the present application is to provide a laser welding method based on plasma temperature control.

[0006] The first technical solution adopted by the present application is a laser welding system based on plasma temperature control, comprising a target stand, an IR laser light source is arranged in front of a panel of the target stand, a filter and a mirror in optical communication are respectively arranged on both sides of the front of the panel of the target stand, and a condenser lens in optical communication is arranged on the side of the filter away from the target stand.

[0007] The first technical solution of the present application is also characterized in that,

[0008] An XY-axis moving platform is arranged below the bottom of the mirror.

[0009] The target stand is made of aluminum.

[0010] The filter is made of zirconium metal.

[0011] The mirror is coated with a molybdenum disilicide coating near the side of the target stand.

[0012] The condenser lens comprises a cylindrical barrel with an open end facing the optical filter, and the inner wall of the barrel is an elliptical arc surface structure coated with a gold plating film.

[0013] The second technical solution adopted by the present application is a method for laser welding by using a laser welding system based on plasma temperature control, comprising the following steps:

[0014] Step 1, place the laser welding system in a vacuum environment, and use an IR laser light source to emit linear IR laser light to irradiate the panel of the target stand, so that linear plasma is generated;

[0015] Step 2, after the linear plasma cools down, electron transition releases short-wave EUV laser light, the first path of the EUV laser light is sequentially collected by the optical filter and the condenser lens at the focal position; adjust the deflection angle of the mirror, so that the second path of the EUV laser light is first reflected by the mirror and then sequentially collected by the optical filter and the condenser lens at the focal position;

[0016] Step 3, place the welding interface to be welded at the focal position, the first path of the EUV laser light irradiates the welding material to generate welding material plasma, and then the second path of the EUV laser light heats the welding material plasma, and the distance between the mirror and the target stand is adjusted to control the time when the second path of the EUV laser light enters the welding material plasma, so as to adjust the temperature and cooling rate of the welding material plasma, and the welding interface is optimized.

[0017] The present application has the following advantages: the laser welding system and method based on plasma temperature control can output high-intensity EUV laser light using a low-cost external IR laser light source, thereby improving energy conversion efficiency and reducing costs; by adjusting the laser incidence time difference to control the plasma, the interface effect is controlled, and finally a balance between interface effect and cost is achieved, making large-scale low-cost application possible, and providing assistance for industrial high-precision operation. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is a structural schematic diagram of the laser welding system based on plasma temperature control of the present application;

[0019] Figure 2 is a condensing principle schematic diagram of the condenser lens in the laser welding system based on plasma temperature control of the present application.

[0020] In the figure, 1 is a target stand, 2 is an IR laser light source, 3 is an optical filter, 4 is a mirror, 5 is a condenser lens, 6 is an XY-axis moving platform, 7 is linear plasma, 8 is a focal position, 9 is the first path of EUV laser light, and 10 is the second path of EUV laser light. Detailed Implementation

[0021] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0022] Example 1

[0023] This invention provides a laser welding system based on plasma temperature control, such as... Figure 1 As shown, it includes a target plate 1, an IR laser source 2 is provided in front of the panel of the target plate 1, and optically connected filters 3 and reflectors 4 are provided on both sides of the front of the panel of the target plate 1, respectively. An XY axis moving platform 6 is provided below the bottom of the reflector 4, and an optically connected condenser 5 is provided on the side of the filter 3 away from the target plate 1.

[0024] The principle underlying the plasma temperature-controlled laser welding system of this invention is as follows: laser welding involves melting materials at high temperatures and then cooling them. This process first transforms the interface material into plasma. Therefore, this invention utilizes the time difference between the laser beams to control the plasma, thereby achieving the goal of controlling the interface effect. Specifically, this invention uses a low-cost external linear IR laser to irradiate a metal target to generate plasma. Because the linear plasma undergoes electron transitions and emits short-wave EUV lasers when it cools, in addition to the EUV laser directly directed at the focusing mirror 5, a reflector 4 is used to reflect the EUV laser, which is opposite to the target direction, back to the focusing mirror 5. This results in two laser beams with a time difference. The first laser beam directly irradiates the welding material to generate plasma from that material, while the second laser beam irradiates the plasma on the welding material (this plasma is not the plasma that emits EUV lasers when the external IR laser irradiates the target), heating it. The distance between the reflector 4 and the target plasma is adjusted by using the XY-axis moving platform 6 to regulate the time difference between the two laser groups. This means that the plasma generated by the first laser has different time intervals before the second laser strikes, resulting in different temperature rises of the plasma generated by the first laser under the influence of the second laser. Since the temperature, heating rate, and cooling rate of the plasma at the welding interface directly affect its smoothness, shortening the time difference between the two laser groups delays the cooling of the plasma generated by the first laser. Then, the second laser heats the plasma, increasing its initial cooling temperature and extending the flow time of the molten material. This allows for more even flow and improved smoothness. In this way, the temperature rise and cooling rate of the plasma are controlled, indirectly controlling the smoothness of the welding interface.

[0025] Example 2

[0026] In Example 1, the preferred embodiment of the plasma temperature-controlled laser welding system of the present invention is as follows:

[0027] The target plate 1 is made of aluminum, which is inexpensive and makes it easy to generate a near-floating linear plasma 7 in front of the target plate 1.

[0028] Filter 3 is a thin sheet made of zirconium metal. The zirconium filter is nearly transparent to EUV lasers of a specific length while blocking the transmission of other wavelengths of light, ensuring that the wavelength of the light entering the condenser lens 5 is the required wavelength, which is beneficial for measuring the spot energy before and after focusing.

[0029] The side of the reflector 4 closest to the target plate is coated with a molybdenum disilicide coating. Since EUV lasers have extremely low reflectivity, a reflector with a molybdenum disilicide coating that has a reflectivity of 60% for a specific EUV is preferred.

[0030] The condenser lens 5 includes a cylindrical body with one end open directly facing the filter. The inner wall of the cylinder has an elliptical arc surface structure and is coated with a gold film. Because the laser has a certain diffusion angle, a very small focal point is required, such as... Figure 2 As shown, a condenser lens 5 with an elliptical arc surface structure is used to focus the EUV laser into a circular focal point with a diameter of less than 1 μm. Since gold has a high reflectivity when the EUV laser is obliquely incident, the EUV laser group is focused by using a gold-coated elliptical reflective surface. This not only increases the light intensity of the focal point, but also increases the temperature of the welding focal point and the cooling of the welding material after melting, thus optimizing the welding interface effect.

[0031] Example 3

[0032] This invention provides a laser welding method based on plasma temperature control, such as... Figure 1 As shown, it includes the following steps:

[0033] Step 1: Place the laser welding system in a vacuum environment and use an IR laser source 2 to emit a linear IR laser to irradiate the panel of the target plate 1, so that it generates linear plasma 7.

[0034] Step 2: After the linear plasma cools down, electron transitions occur, releasing short-wave EUV laser. The first path of the EUV laser is focused at the focal point 8 by the filter 3 and the condenser 5 in sequence. The deflection angle of the reflector 4 is adjusted so that the second path of the EUV laser is reflected by the reflector 4 and then focused at the focal point 8 by the filter 3 and the condenser 5 in sequence.

[0035] Step 3: Place the interface to be welded at the focal position 8. After the first EUV laser 9 irradiates the material to be welded, it generates welding material plasma. Then, the second EUV laser 10 heats the welding material plasma. By adjusting the distance between the reflector 4 and the target plate 1, the time for the second EUV laser 10 to enter the welding material plasma is controlled, thereby adjusting the temperature and cooling rate of the welding material plasma and optimizing the welding interface.

Claims

1. A laser welding method based on plasma temperature control, characterized in that, A laser welding system based on plasma temperature control is adopted, including a target plate (1), an IR laser source (2) is arranged in front of the panel of the target plate (1), and optically connected filters (3) and reflectors (4) are respectively arranged on both sides of the front of the panel of the target plate (1). An optically connected condenser (5) is arranged on the side of the filter (3) away from the target plate (1); the laser welding method includes the following steps: Step 1: Place the laser welding system in a vacuum environment and use an IR laser source (2) to emit a linear IR laser to irradiate the panel of the target plate (1) so that it generates linear plasma (7). Step 2: After the linear plasma cools down, electron transitions occur, releasing short-wave EUV laser. The first path of the EUV laser is focused at the focal point (8) by the filter (3) and the condenser (5) in sequence. The deflection angle of the reflector (4) is adjusted so that the second path of the EUV laser is reflected by the reflector (4) and then focused at the focal point (8) by the filter (3) and the condenser (5) in sequence. Step 3: Place the interface to be welded at the focal position (8). After the first EUV laser (9) irradiates the material to be welded, it generates welding material plasma. Then, the second EUV laser (10) heats the welding material plasma. By adjusting the distance between the reflector (4) and the target plate (1), the time for the second EUV laser (10) to enter the welding material plasma is controlled to adjust the temperature and cooling rate of the welding material plasma, thereby optimizing the welding interface.

2. The laser welding method based on plasma temperature control as described in claim 1, characterized in that, An XY axis moving platform (6) is provided below the bottom of the reflector (4).

3. The laser welding method based on plasma temperature control as described in claim 1, characterized in that, The target support plate (1) is made of aluminum.

4. The laser welding method based on plasma temperature control as described in claim 1, characterized in that, The filter (3) is made of zirconium metal.

5. The laser welding method based on plasma temperature control as described in claim 1, characterized in that, The reflector (4) is covered with a molybdenum disilicide coating on the side near the target plate.

6. The laser welding method based on plasma temperature control as described in claim 1, characterized in that, The condenser lens (5) includes a cylindrical body with one end open and facing the filter. The inner wall of the cylinder has an elliptical arc surface structure and is covered with a gold coating.

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