WO2021129468A1

WO2021129468A1 - Dual-spot-based slm forming system and method

Info

Publication number: WO2021129468A1
Application number: PCT/CN2020/136628
Authority: WO
Inventors: 杨东辉; 李洋; 薛蕾
Original assignee: 西安铂力特增材技术股份有限公司
Priority date: 2019-12-26
Filing date: 2020-12-15
Publication date: 2021-07-01
Also published as: CN110918994A

Abstract

A dual-spot-based SLM forming system (20) and a method. The system (20) comprises a first laser source portion (21), a second laser source portion (22), a beam combining assembly (23) and a light path guide portion (24), wherein the first laser source portion (21) is configured to emit a first laser beam, and the energy density of a cross-sectional center of the first laser beam is greater than or equal to a set energy density threshold value; the second laser source portion (22) is configured to emit a second laser beam, the energy density of the cross-section of the second laser beam is less than the energy density threshold value, and the cross-sectional diameter of the second laser beam is greater than the cross-sectional diameter of the first laser beam; the beam combining assembly (23) is configured to combine the first laser beam with the second laser beam to form a combined beam, and in the combined beam, the cross-section of the first laser beam is within the cross-section of the second laser beam; and the light path guide portion (24) is configured to direct the combined beam to metal powder (9) located in a forming plane (7), thereby reducing thermal stress and improving the forming quality.

Description

A SLM forming system and method based on double light spots

Cross references to related applications

This application is filed based on the Chinese patent application with the application number 201911367911.7 and the filing date on December 26, 2019, and claims the priority of the Chinese patent application. The content of the Chinese patent application is hereby incorporated into this application by reference.

Technical field

The invention belongs to selective laser melting (SLM, Selective Laser Melting) equipment technology, and specifically relates to a dual-spot-based SLM forming system and method.

Background technique

With the development of SLM technology, various SLM equipment has emerged, but in the process of using SLM equipment to process parts, because the local temperature of the parts will experience a sudden increase with the processing conditions, and then rapidly cool down, It is easy to cause greater thermal stress on the parts, and as the thermal stress concentrates, it will eventually cause damage to the parts, such as warping, cracking, and deformation of the parts.

At present, the related technology has involved research on the control of the molten pool and the temperature field in the SLM forming process. According to the complexity of laser processing, the temperature measurement method is actually applied to SLM equipment to perform real-time detection of temperature field distribution; however, even if the temperature field distribution of the part is obtained through real-time detection, it is difficult to avoid the concentration of thermal stress of the part. The real-time change of the part temperature adjusts the SLM forming strategy. In addition, the real-time detection effect needs to be further verified.

Summary of the invention

The embodiment of the present invention provides an SLM forming system and method based on dual light spots, which solves the problems of high thermal effect and easy cracking and deformation of the parts when the parts are processed by the existing SLM equipment.

The technical solution of the embodiment of the present invention is realized as follows:

In the first aspect, an embodiment of the present invention provides a dual-spot-based SLM forming system, the system includes: a first laser source part, a second laser source part, a beam combining component, and a light path guiding part;

Wherein, the first laser source part is configured to emit a first laser beam, wherein the energy density at the center of the section of the first laser beam is greater than or equal to a set energy density threshold;

The second laser source part is configured to emit a second laser beam; wherein the energy density of the cross-section of the second laser beam is less than the energy density threshold, and the cross-sectional diameter of the second laser beam is greater than the energy density threshold. The cross-sectional diameter of the first laser beam;

The beam combining component is configured to combine the first laser beam and the second laser beam to form a combined beam; in the combined beam, the cross section of the first laser beam is in the second In the cross-section of the laser beam;

The light path guiding part is configured to guide the combined light beam to the metal powder located on the forming plane.

In a second aspect, an embodiment of the present invention provides a dual-spot-based SLM forming method, which is applied to the dual-spot-based SLM forming system described in the first aspect, and the method includes:

The first laser beam and the second laser beam are combined to form a combined beam; wherein the energy density at the center of the section of the first laser beam is greater than or equal to a set energy density threshold; The energy density is less than the energy density threshold, and the cross-sectional diameter of the second laser beam is greater than the cross-sectional diameter of the first laser beam; in the combined beam, the cross-section of the first laser beam is in the second In the cross-section of the laser beam;

The combined light beam is guided to the metal powder located on the forming plane.

In the third aspect, an embodiment of the present invention provides a dual-spot-based SLM forming system, which includes a laser a, a half lens, and a collimating beam expander arranged in sequence. A laser b is installed above the half lens, and a beam a and a beam emitted by the laser a The beam b emitted by the laser b is transmitted to the collimating beam expander through the semi-lens. The collimating beam expander combines the beam a and the beam b into parallel beams. The parallel beams pass through the galvanometer and the static focusing lens in turn to reach the metal powder and metal powder. Located on the forming plane.

With reference to the third aspect, the embodiments of the present invention are also characterized by:

Both laser a and laser b are continuous lasers.

The beam of laser a is smaller than that of laser b.

The beam of laser a is located at the center of the beam of laser b.

The side of the half lens close to the laser a is provided with a fully transparent film, the side of the half lens close to the laser b is provided with a total reflection film, and the half lens is used to transmit and reflect the light beam.

In a fourth aspect, an embodiment of the present invention provides a dual-spot-based SLM forming system, which includes a laser a, a half lens, and a dynamic focus lens arranged in sequence, a laser b is installed above the half lens, and the beam a and laser b emitted by laser a The emitted light beam b is transmitted to the dynamic focusing mirror through the semi-lens. The dynamic focusing mirror deflects the light beam a and the light beam b to the galvanometer, and the galvanometer deflects the light beam a and the light beam b to the metal powder, and the metal powder is located on the forming plane.

With reference to the fourth aspect, the embodiment of the present invention is also characterized by:

Both laser a and laser b are continuous lasers.

The beam of laser a is smaller than that of laser b.

The beam of laser a is located at the center of the beam of laser b.

Compared with related technologies, the embodiments of the present invention have the following beneficial effects:

Since the cross section of the first laser beam is within the cross section of the second laser beam, and the energy density of the first laser beam is greater than or equal to the energy density threshold, the energy density of the second laser beam is less than the energy density threshold, so During the SLM forming process, the first laser beam in the combined beam can be used to melt the metal powder to form a molten pool to shape the part; and at the same time, the second laser beam can also be used to process the front end of the molten pool. The metal powder is preheated, and the formed parts at the back end of the molten pool are slowly cooled to reduce the temperature gradient during the forming process, which greatly reduces the heat generated by the sharp changes in the temperature of the formed parts. Stress, thereby improving the forming quality of the part.

Description of the drawings

Fig. 1 is a schematic diagram of energy density distribution in a Gaussian distribution in related technologies;

2 is a schematic diagram of the composition of a dual-spot-based SLM forming system provided by an embodiment of the present invention;

FIG. 3 is a schematic diagram of the composition of another dual-spot-based SLM forming system provided by an embodiment of the present invention;

4 is a schematic diagram of the energy density distribution of the combined light beam provided by an embodiment of the present invention;

5 is a schematic cross-sectional view of a combined beam provided by an embodiment of the present invention;

FIG. 6 is a schematic diagram of the composition of yet another SLM forming system based on dual beams provided by an embodiment of the present invention;

FIG. 7 is a schematic diagram of the composition of yet another SLM forming system based on dual beams provided by an embodiment of the present invention;

FIG. 8 is a detailed structural diagram of a dual-spot-based SLM forming system provided by an embodiment of the present invention;

FIG. 9 is a detailed structural diagram of another SLM forming system based on dual beams provided by an embodiment of the present invention;

FIG. 10 is an energy distribution diagram of the dual spot in the SLM dual spot forming system provided by an embodiment of the present invention;

FIG. 11 is a schematic flowchart of a dual-spot-based SLM forming method provided by an embodiment of the present invention.

Detailed ways

The present invention will be described in detail below with reference to the drawings and specific embodiments.

In the metal printing process, especially during the SLM forming process, in order to avoid the parts being damaged due to the large thermal stress caused by the rapid temperature change, the temperature field and stress field during the SLM forming process can be controlled to reduce the SLM forming process. The thermal stress generated in the process reduces the probability of damage to the parts. For example, while preheating the metal powder at the front end of the molten pool, slow cooling of the formed parts at the rear end of the molten pool can be used to reduce the temperature gradient during the SLM forming process, thereby reducing thermal stress. Take a laser beam with a circular spot as an example. The central area of the spot requires a larger laser energy density to cause a melting depth of metal powder that exceeds its layer thickness, and a smaller laser energy density is required at the edge area of the spot. The metal powder is sintered and cladding overlapped.

However, in the related art, a single laser source is usually used for SLM forming processing, and the energy density distribution of the laser beam emitted by the laser source is Gaussian. As shown in Figure 1, the energy density of the laser beam central region 1 and the laser beam The energy density of the edge area 2 has a large gradient; for example, when the diameter D of the light spot formed by the beam, that is, the spot size is certain, if it is necessary to realize that the metal powder is caused to exceed its layer thickness in the central area 1 of the light spot Melting depth, then it is necessary to increase the energy density of the spot center area 1 so that the energy density of the spot edge area 2 is not enough to perform good sintering and cladding of the metal powder; if it is necessary to realize the metal powder in the spot edge area 2 To perform good sintering and cladding overlap, it is necessary to increase the energy density of the spot edge area 2 so that the energy density of the spot center area 1 is not enough to cause the metal powder to melt beyond its layer thickness. Therefore, the use of a single laser source in the related SLM forming technology cannot simultaneously achieve a melting depth of the metal powder exceeding its layer thickness in the central region 1 and good sintering and cladding of the metal powder in the edge region 2 at the same time. In addition, corresponding to the energy density distribution shown in Figure 1, during the SLM molding process, the temperature of the spot center area 1 and the temperature of the spot edge area 2 is between the temperature of the spot center area 1 and the temperature outside the spot edge area 2. There is a large gradient between the temperature of the forming or to-be-formed area, which can easily lead to greater thermal stress on the part and cause damage to the part.

In order to avoid the phenomenon caused by the above-mentioned related technologies, refer to FIG. 2, which shows a dual-spot-based SLM forming system 20 provided by an embodiment of the present invention. The system 20 may include: a first laser source part 21, a first laser source part 21, and a second laser source part 21. Two laser source part 22, beam combining assembly 23 and light path guiding part 24;

Wherein, the first laser source part 21 is configured to emit a first laser beam, as shown by the solid line in FIG. 2, the energy density of the center of the section of the first laser beam is greater than or equal to a set energy density threshold ；

The second laser source part 22 is configured to emit a second laser beam, as shown by the dashed line in FIG. 2; the energy density of the section of the second laser beam is less than the energy density threshold, and the second laser beam The cross-sectional diameter of the beam is greater than the cross-sectional diameter of the first laser beam;

The beam combining component 23 is configured to combine the first laser beam and the second laser beam to form a combined beam; in the cross-section of the combined beam, the cross-section of the first laser beam is at the same position. In the cross section of the second laser beam;

The light path guiding part 24 is configured to guide the combined light beam to the metal powder 9 located on the forming plane 7.

For the system 20 shown in FIG. 2, it should be noted that the energy density threshold is used to characterize the lowest value of the energy density that can cause the metal powder to melt at a depth exceeding its layer thickness, that is, if the energy density of the laser beam If the energy density is greater than or equal to the threshold value, the laser beam can melt the metal powder; if the energy density of the laser beam is less than the energy density threshold, the laser beam cannot melt the metal powder. Based on this, in the system shown in Figure 2, since the cross-section of the first laser beam is within the cross-section of the second laser beam, and the energy density of the first laser beam is greater than or equal to the energy density threshold, the The energy density is less than the energy density threshold. Therefore, during the SLM forming process of the system 20 in the direction indicated by the black arrow in FIG. 2, the first laser beam in the combined beam can be used to melt the metal powder. Thus, the molten pool 8 is formed to shape the parts; and at the same time, the second laser beam can also be used to preheat the metal powder to be processed at the front end of the molten pool 8 and slowly cool the formed parts 10 at the rear end of the molten pool 8. Reducing the temperature gradient during the forming process greatly reduces the thermal stress of the formed part 10 due to the sudden temperature rise and drop, thereby improving the forming quality of the part 10.

For the technical solution shown in FIG. 2, in some possible implementation manners, referring to FIG. 3, the first laser source part 21 includes a first laser 211 for generating the first laser beam; the second laser The source part 22 includes a second laser 221 and a beam shaper 222; wherein, the beam shaper 222 converts the laser beam to be shaped emitted by the second laser 221 into a second laser beam with a flat-topped uniform distribution of energy density. .

For the above implementation, specifically, the energy density distribution of the laser beam emitted by the laser is generally as shown in Figure 1, which is a Gaussian distribution. However, the Gaussian distribution leads to uneven energy density distribution, resulting in high temperature gradients and failure to achieve a higher temperature gradient. Good preheating and slow cooling effect. Based on this, in the foregoing implementation manner, the beam shaper 222 is used to convert the laser beam to be shaped emitted by the second laser 221 into a second laser beam with a flat-top uniform distribution of energy density, so that the energy density of the formed combined beam is The distribution is shown in Figure 4. It is assumed that the cross-sections of the first laser beam and the second laser beam are both circular, D1 is the cross-sectional diameter of the first laser beam shown by the dotted circle, and D2 is the second laser beam shown by the solid circle The cross-sectional diameter of the beam. The energy density of the central area of the first laser beam cross-section is greater than or equal to the energy density threshold. Therefore, the central area of the first laser beam can melt the metal powder to complete the forming process. In addition, the cross-sectional diameter of the second laser beam is larger than the cross-sectional diameter of the first laser beam and the cross-section of the first laser beam is within the cross-section of the second laser beam. Therefore, the cross-section of the second laser beam does not coincide with the cross-section of the first laser beam. The area can not only preheat the metal powder to be processed, but also slowly cool the processed parts; and, because the energy density distribution of the second laser beam is evenly distributed, it can maintain a stable preheating and slow cooling Temperature, so as to achieve a better preheating and slow cooling effect. For the above implementation, in some examples, both the first laser 211 and the second laser 221 are preferably continuous lasers.

Understandably, since the technical solution of the embodiment of the present invention distinguishes the laser beams used for SLM forming processing and preheating and slow cooling according to energy density, the power of the first laser 211 is usually selected to be greater than the power of the second laser 221 . However, the energy density is usually obtained by dividing the power by the cross-sectional area of the laser beam. Therefore, even if the power of the first laser 211 is smaller than that of the second laser 221, the cross-sectional area of the first laser beam can still be reduced to increase the cross-sectional area of the first laser beam. The energy density is made greater than the energy density threshold; and the cross-sectional area of the second laser beam is increased to reduce the energy density of the second laser beam to make it smaller than the energy density threshold. Based on this, in the embodiment of the present invention, the power comparison between the first laser 211 and the second laser 221 is not specifically limited.

For the technical solution shown in FIG. 2, in combination with the above description, in the combined beam, the area where the cross section of the second laser beam does not overlap with the cross section of the first laser beam is used for preheating and slow cooling, in order to improve the preheating and slow cooling effect. Consistency can make the length of warm-up and slow-cooling consistent. In some possible implementation manners, in the combined beam, the cross-sectional center of the first laser beam coincides with the cross-sectional center of the second laser beam. Based on this implementation, it can be understood that when the cross-sectional center of the first laser beam coincides with the cross-sectional center of the second laser beam, the combined beam is specifically a coaxial combined beam as shown in FIG. In 5, the black circle represents the cross-section 51 of the first laser beam, and the cross-line circle represents the area where the cross-section 52 of the second laser beam does not overlap with the cross-section 51 of the first laser beam. It can be seen from FIG. 5 that the distance from the edge of the section 51 of the first laser beam from any direction to the edge of the section 52 of the second laser beam is the same. Therefore, when the SLM forming process is a uniform speed process, the length of the preheating period is relatively slow. The length of the cooling period is the same, thereby improving the consistency of the preheating and slow cooling effect.

For the system 20 shown in FIG. 2, in some possible implementations, as shown in FIG. 3, the beam combining component 23 includes a half lens 230; wherein, the half lens 230 faces the first laser source portion 21 The first surface of the semi-lens 230 is provided with a fully transparent film 231 for transmitting the first laser beam; the second surface of the semi-lens 230 facing the second laser source portion 22 is provided with a fully reflective film 232 for reflecting the laser beam The second laser beam and the reflected second laser beam and the transmitted first laser beam are combined into the combined beam.

For the above implementation, preferably, the first laser source part 21 and the second laser source part 22 can be arranged vertically, so that the first laser beam and the second laser beam are perpendicular to each other. Facing the first laser source part 21 and the angle between the first laser beam and the first laser beam is set to 45 degrees, the first laser beam and the second laser beam can be combined into a coaxial combined beam through the half lens 230 , Its cross-section forms a concentric ring as shown in Figure 5. It should be noted that the above-mentioned preferred example is not the only solution for combining the first laser beam and the second laser beam into a coaxial combined beam. It is understandable that in the specific implementation process, the first laser source part 21 and the second laser beam The actual arrangement of the laser source part 22 adjusts the angle between the half lens 230 and the first laser beam, so that the first laser beam and the second laser beam can be combined into a coaxial combined beam through the half lens 230. The implementation of the present invention This example does not repeat this.

For the system 20 shown in FIG. 2, in some possible implementations, as shown in FIG. 6, the light path guiding part 24 includes: a collimating beam expander 241, a galvanometer 242, and a static focusing lens 243; among them, The collimating beam expander 241 is configured to form the combined light beam into a parallel combined light beam, and the galvanometer 242 is configured to reflect the parallel combined light beam to the static focusing mirror 243; The static focusing mirror 243 is configured to focus the parallel combined light beam into a focused combined light beam, and guide the focused combined light beam to the metal powder 9 located on the forming plane 7.

For the foregoing implementation, it should be noted that the collimating beam expander 241 can adjust the cross-sectional diameter of the combined beam and adjust the combined beam to be a parallel beam; the parallel combined beam can be arranged along X/Y after passing through the galvanometer 242. The beam deflection and optical path adjustment achieved by the axis-rotating optical mirror can still keep the beam parallel; then, the parallel combined beam is focused by the fixed static focusing mirror 243, so that the first laser beam is in the focused combined beam The cross-sectional diameter meets the technological requirements of SLM forming processing.

For the system 20 shown in FIG. 2, in some possible implementation manners, as shown in FIG. 7, the light path guide portion 24 includes: a dynamic focus mirror 245 and a galvanometer 242; wherein, the dynamic focus mirror 245, Is configured to focus the combined light beam based on moving the position of the dynamic focus mirror 245, and deflect the focused combined light beam to the galvanometer 242; the galvanometer 242 is configured to focus the focused beam The combined light beam is deflected to the metal powder 9 located on the forming plane 7.

For the above implementation, it should be noted that, different from the implementation shown in FIG. 6, the dynamic focus lens 245 is not fixed as the static focus lens 243, and the dynamic focus lens 245 can be movably set. During the movement, the dynamic focus lens 245 can be set movably. The position of the focusing lens 245 is different, and the focusing size is also different. Therefore, the dynamic focusing lens 245 can be moved to adjust the cross-sectional diameter of the focused combined beam. Understandably, based on the movability of the dynamic focus lens 245, it is difficult to control the accuracy during assembly and debugging of the dynamic focus lens 245 in the specific implementation process. Therefore, the implementation shown in FIG. 6 is compared with that shown in FIG. 7 The realization method is easier to realize.

Based on the foregoing technical solution, the embodiment of the present invention also provides a specific implementation solution of an SLM forming system based on a dual-spot.

Referring to FIG. 8, it shows a detailed structural diagram of a dual-spot-based SLM forming system provided by an embodiment of the present invention, including a laser a 81, a half lens 83 and a collimating beam expander 84 arranged in sequence, above the half lens 83 A laser b 82 is installed. The beam a emitted by the laser a 81 and the beam b emitted by the laser b 82 are transmitted to the collimating beam expander 84 through the half lens 83, and the collimating beam expander 84 combines the beam a and the beam b into parallel The light beam and the parallel light beam sequentially pass through the galvanometer 85 and the static focusing lens 86 to reach the metal powder 9, and the metal powder 9 is located on the forming plane.

For the detailed structure shown in FIG. 8, in some examples, the arrangement sequence of the half lens 83 and the collimating beam expander 84 along the optical path can be changed. For example, the collimating beam expander 84 can also be arranged on the half lens. 83 in front. It should be noted that if the cross-sectional dimensions of the two lasers are equal to or close to the desired cross-sectional dimensions, the collimating beam expander 84 is preferably arranged behind the half lens 83 along the optical path, and some fine adjustments are made. If the cross-sectional size of the two lasers is not in proportion to the desired cross-sectional size, it is preferable to arrange the collimating beam expander 84 along the optical path before the semi-lens 83, that is, before the beam enters the semi-lens 83 Previously, the size adjustment of the cross-sectional size was completed by the collimating beam expander 84.

Preferably, the laser a 81 and the laser b 82 are both continuous lasers.

Preferably, the beam of laser a 81 is smaller than the beam of laser b 82; the beam of laser a 81 is located at the center of the beam of laser b 82.

Preferably, the side of the half lens 83 close to the laser a 81 is provided with a fully transparent film, the side of the half lens 83 close to the laser b 82 is provided with a total reflection film, and the half lens 83 is used to transmit and reflect the light beam.

It should be noted that the working principle of the dual-spot-based SLM forming system shown in Fig. 8 is as follows:

First, read the current layer printing data in the printed file through the computer, and send the information to the SLM forming system based on dual-spots, and control the laser a 81 and the laser b 82 to emit lasers of specified power respectively, and pass the two lasers through the half lens 83 Converges into a coaxial composite laser beam; the coaxial composite laser beam passes through the collimating beam expander 84 and then enters the galvanometer 85 for reflection. The reflected laser can be focused by the static focusing mirror 86 into a laser spot size that meets the forming requirements, as shown in the figure As shown at 10, the metal powder 9 is melted and formed at the designated position of the forming platform at the same time.

Refer to FIG. 9, which shows a detailed structural schematic diagram of another SLM forming system based on dual-spot provided by an embodiment of the present invention, including a laser a 81, a half lens 83 and a dynamic focus lens 11 arranged in sequence, above the half lens 83 A laser b 82 is installed. The beam a emitted by the laser a 81 and the beam b emitted by the laser b 82 are transmitted to the dynamic focus lens 11 through the semi-lens 83, and the dynamic focus lens 11 deflects the beam a and the beam b to the galvanometer 85, the galvanometer 85 deflects the beam a and the beam b to the metal powder 9, which is located on the forming plane.

For the detailed structure shown in FIG. 9, in some examples, a collimating beam expander can still be provided in the optical path. In detail, since the dynamic focus mirror 11 itself has the function of focusing and beam expansion, in the specific implementation process, if the beam expansion capability of the dynamic focus mirror 11 can meet the needs of specific applications, then as shown in Figure 9 As shown, there is no need to additionally provide a collimating beam expander in the optical path; if the beam expansion capability of the dynamic focus lens 11 cannot meet the requirements of specific applications, preferably, a collimating beam expander can be additionally provided in the optical path before the half lens 83. The beam mirror adjusts the cross-sectional size of the laser beam to match.

Preferably, the laser a 81 and the laser b 82 are both continuous lasers.

It should be noted that the working principle of another dual-spot-based SLM forming system shown in Fig. 9 is as follows:

First, read the current layer print data in the print file through the computer, send the information to the dynamic focusing SLM dual-spot forming system of the present invention, and control the laser a 81 and the laser b 82 to emit lasers of specified power respectively, and pass the two lasers through The semi-lens 83 merges into a coaxial composite laser beam; the coaxial composite laser beam can be focused to a laser spot size that meets the forming requirements through the dynamic focusing mirror 11, as shown in Figure 10, and then reflected by the galvanometer 85 to a designated position on the forming plane The melting and forming of the metal powder 9 are realized on the above.

Figure 10 shows the size of the laser spot and the corresponding beam energy distribution. The laser beam a produced by the low-power laser a 81 has a relatively small size, and its laser energy distribution is Gaussian, with a high central energy density, which can be used for the melting of metal powder 9; The size of the laser beam b generated by the power laser b 82 is relatively large. After processing, the laser energy distribution is flat and uniform, and the energy density is relatively low. It will not melt the metal powder 9 and is only used for preheating the metal powder 9. Slow cooling of parts;

As shown in Figures 8 and 9, the two laser beams generated by the laser a 81 and the laser b 82 of the present invention are combined into a coaxial composite laser beam through a half lens 83, and the coaxial composite laser beam gradually forms the formed part 10 on the forming plane. , Forming a molten pool 8 at the same time;

While meeting the forming requirements, the coaxial composite laser beam can not only preheat the metal powder 9 at the front end of the molten pool 8, but can also slowly cool the formed parts 10 at the rear end of the molten pool 8 to a great extent. The thermal stress of the formed part 10 due to the sudden rise and drop in temperature is reduced, thereby improving the forming quality of the formed part 10.

Based on the same inventive concept as the foregoing technical solution, refer to FIG. 11, which shows the flow of a dual-spot-based SLM forming method provided by an embodiment of the present invention. The method is applied to the dual-spot-based forming method described in the foregoing technical solution. The SLM forming system 20, the method includes:

S1101: Combine the first laser beam and the second laser beam to form a combined beam;

Wherein, the energy density of the cross-sectional center of the first laser beam is greater than or equal to a set energy density threshold; the energy density of the second laser beam's cross-section is less than the energy density threshold, and the energy density of the second laser beam is The cross-sectional diameter is greater than the cross-sectional diameter of the first laser beam; in the cross-section of the combined beam, the cross-section of the first laser beam is within the cross-section of the second laser beam;

S1102: Guide the combined light beam to the metal powder located on the forming plane.

In the above solution, the method further includes: emitting the first laser beam through a first laser;

The second laser emits the laser beam to be shaped, and the beam shaper converts the laser beam to be shaped into the second laser beam whose energy density is uniformly distributed.

In the above solution, in the combined beam, the cross-sectional center of the first laser beam coincides with the cross-sectional center of the second laser beam.

In the above solution, the combining the first laser beam and the second laser beam to form a combined beam includes:

Transmitting the first laser beam by using a half-lens full-transmitting film;

The second laser beam is reflected by the total reflection film of the half lens and the reflected second laser beam and the transmitted first laser beam are combined into the combined beam.

In the above solution, the guiding the combined light beam to the metal powder located on the forming plane includes:

Using a collimating beam expander to form the combined light beam into a parallel combined light beam;

Using a galvanometer mirror to reflect the parallel combined light beam to a static focusing mirror;

The static focusing lens is used to focus the parallel combined light beam into a focused combined light beam, and guide the focused combined light beam to the metal powder located on the forming plane.

Focusing the combined light beam by moving the position of the dynamic focusing lens, and deflecting the focused combined light beam to the galvanometer;

A galvanometer is used to deflect the focused combined light beam to the metal powder located on the forming plane.

It should be noted that the dual-spot-based SLM forming method shown in FIG. 11 can be specifically implemented by the dual-spot-based SLM forming system 20 described in the foregoing technical solution. For the relevant description of the specific implementation process, refer to the foregoing description of the dual-spot-based SLM forming method. The detailed description of the SLM forming system 20 of the light spot and its implementation manners will not be repeated here.

It should be noted that the technical solutions described in the embodiments of the present invention can be combined arbitrarily without conflict.

The above are only specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention. It should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Industrial applicability

In the embodiment of the present invention, since the cross section of the first laser beam is within the cross section of the second laser beam, and the energy density of the first laser beam is greater than or equal to the energy density threshold, the energy density of the second laser beam is less than the energy Therefore, in the process of SLM forming processing, the first laser beam in the combined beam can be used to melt the metal powder to form a molten pool to shape the part; and at the same time, the second laser beam can also be used to melt the metal powder. The metal powder to be processed at the front end of the pool is preheated, and the formed parts at the back end of the molten pool are slowly cooled to reduce the temperature gradient during the forming process, which greatly reduces the sudden drop in temperature of the formed parts due to the sudden rise in temperature. The thermal stress caused by the sharp change improves the forming quality of the part.

Claims

A dual-spot-based SLM forming system, characterized in that the system includes: a first laser source part, a second laser source part, a beam combining component, and a light path guiding part;

Wherein, the first laser source part is configured to emit a first laser beam, wherein the energy density at the center of the section of the first laser beam is greater than or equal to a set energy density threshold;

The second laser source part is configured to emit a second laser beam; wherein the energy density of the cross-section of the second laser beam is less than the energy density threshold, and the cross-sectional diameter of the second laser beam is greater than the energy density threshold. The cross-sectional diameter of the first laser beam;

The beam combining component is configured to combine the first laser beam and the second laser beam to form a combined beam; in the cross section of the combined beam, the cross section of the first laser beam is in the In the cross section of the second laser beam;

The light path guiding part is configured to guide the combined light beam to the metal powder located on the forming plane.
The system according to claim 1, wherein the first laser source part includes a first laser for generating the first laser beam; the second laser source part includes a second laser and a beam shaper Wherein, the beam shaper converts the laser beam to be shaped emitted by the second laser into a second laser beam with an energy density distribution that is uniformly distributed.
The system according to claim 2, wherein the first laser and the second laser are both continuous lasers.
The system according to claim 1, wherein in the combined beam, the cross-sectional center of the first laser beam coincides with the cross-sectional center of the second laser beam.
The system according to claim 1, wherein the beam combining component comprises a semi-lens; wherein the first surface of the semi-lens facing the first laser source part is provided with a fully transparent film for transmitting the light source. The first laser beam; the second surface of the half-lens facing the second laser source portion is provided with a total reflection film for reflecting the second laser beam and combining the reflected second laser beam with the transmitted The first laser beam is combined into the combined beam.
The system according to claim 1, wherein the optical path guide part comprises: a collimating beam expander, a galvanometer, and a static focusing lens; wherein the collimating beam expander is configured to The combined light beam is formed into a parallel combined light beam, the galvanometer mirror is configured to reflect the parallel combined light beam to the static focus mirror; the static focus mirror is configured to focus the parallel combined light beam to form Is a focused combined light beam, and guides the focused combined light beam to the metal powder located on the forming plane.
The system according to claim 1, wherein the optical path guide part comprises: a dynamic focus mirror and a galvanometer; wherein the dynamic focus mirror is configured to move the dynamic focus mirror based on the position of the dynamic focus mirror. The combined beam is focused, and the focused combined beam is deflected to the galvanometer; the galvanometer is configured to deflect the focused combined beam to the metal powder located on the forming plane.
A dual-spot-based SLM forming method, characterized in that the method is applied to the dual-spot-based SLM forming system according to any one of claims 1 to 7, and the method comprises:

The first laser beam and the second laser beam are combined to form a combined beam; wherein the energy density at the center of the section of the first laser beam is greater than or equal to a set energy density threshold; The energy density is less than the energy density threshold, and the cross-sectional diameter of the second laser beam is greater than the cross-sectional diameter of the first laser beam; in the cross-section of the combined beam, the cross-section of the first laser beam is in the In the cross section of the second laser beam;

The combined light beam is guided to the metal powder located on the forming plane.
The method according to claim 8, wherein the energy density distribution of the second laser beam is a flat top uniform distribution;

In the combined beam, the cross-sectional center of the first laser beam coincides with the cross-sectional center of the second laser beam.
8. The method of claim 8, wherein the combining the first laser beam and the second laser beam to form a combined beam comprises:

Transmitting the first laser beam by using a half-lens full-transmitting film;

The second laser beam is reflected by the total reflection film of the half lens and the reflected second laser beam and the transmitted first laser beam are combined into the combined beam.
The method according to claim 8, wherein the guiding the combined light beam to the metal powder located on the forming plane comprises:

Using a collimating beam expander to form the combined light beam into a parallel combined light beam;

Using a galvanometer mirror to reflect the parallel combined light beam to a static focusing mirror;

The static focusing lens is used to focus the parallel combined light beam into a focused combined light beam, and guide the focused combined light beam to the metal powder located on the forming plane.
The method according to claim 8, wherein the guiding the combined light beam to the metal powder located on the forming plane comprises:

Focusing the combined light beam by moving the position of the dynamic focusing lens, and deflecting the focused combined light beam to the galvanometer;

A galvanometer is used to deflect the focused combined light beam to the metal powder located on the forming plane.