CN115213426B - Laser melting forming method and system - Google Patents

Abstract

The invention relates to the technical field of laser processing, and discloses a laser melting forming method and a laser melting forming system, wherein the method comprises the following steps: determining a first part frame area and a first entity filling area according to a first layer processing parameter corresponding to a layer number; carrying out laser scanning on the frame area of the first part through a first laser beam; controlling the phase angle of the second laser beam to deflect a first angle, and carrying out laser scanning on the first entity filling area through the second laser beam; and controlling the phase angle of the third laser beam to deflect a second angle, and confirming that the layer processing corresponding to the layer number is completed after the third laser beam performs laser remelting scanning on the first entity filling area. The invention avoids the heat accumulation of local areas, effectively reduces the porosity of the laser melting molded part, realizes the high density of the final molded part, and has low cost and simple operation.

Description

Laser melting forming method and system

Technical Field

The present invention relates to the technical field of laser processing, and in particular to a laser melting forming method and system.

Background technique

Selective laser melting is an additive manufacturing technology that uses a laser beam to completely melt metal powder and solidify it through cooling. It is an important sub-technical field of metal 3D printing technology. It is not affected by the complexity of the parts and has incomparable advantages over traditional casting methods. It does not require molds and is particularly suitable for rapid product verification. At present, when using selective laser melting technology for forming processing, a laser beam is used as a heat source to melt and form a two-dimensional cross-section layer by layer, accumulating layer by layer, and finally realizing the processing of three-dimensional parts. However, during the molding process, due to the combined influence of raw material quality, molding process parameters and molding process characteristics, for example, the gas entrained in the hollow powder in the raw materials will eventually accumulate in the molded parts to form holes. Unreasonable molding process parameters lead to uneven melting of the molten pool, splashing of droplets, incomplete melting of raw materials, etc., forming holes. The characteristics of the molding process cause the metal powder to form a molten pool under the thermal shock of the laser. At the same time, part of the metal is vaporized. When the laser is turned off, a large recoil pressure is formed. Under the action of the recoil pressure, the metal liquid flows to the center of the molten pool, forming a closed keyhole at the bottom of the molten pool. The metal vapor will be captured by the solidification front to form a nearly circular keyhole, which finally causes the density of the part to be low and affects the mechanical properties of the part.

In the prior art, in order to reduce the holes, after completing the selective laser forming, a post-processing process is usually added to the molded parts (such as hot isostatic pressing technology: the parts are placed in a special package, which can be made of metal or ceramic, and then nitrogen or argon is used as a pressurizing medium to perform thermal densification treatment on the parts with shrinkage cavities under high temperature and high pressure to reduce the porosity, thereby achieving high density of the molded parts and achieving the required performance requirements). The shortcomings of this solution are that, firstly, it is necessary to customize the package for each part according to the part structure, which takes a lot of time and increases the cost; at the same time, the hot isostatic pressing technology is complex and involves many parameters. It is necessary to formulate matching process parameters according to different materials to ensure performance; thirdly, the popularity of hot isostatic pressing technology is extremely low, and it has not yet been scaled up and industrialized, which further increases the production cost.

Summary of the invention

The embodiments of the present invention provide a laser melting forming method and system, which solve the problems of complex process and high cost in the prior art method for reducing the porosity of laser melting formed parts.

To achieve the above object, the present invention provides a laser melting forming method, comprising:

receiving a first layer processing instruction including a layer number of a part to be processed, and laying a layer of alloy powder with a preset thickness;

Determine a first part frame area and a first entity filling area corresponding to the layer of alloy powder according to the first layer processing parameters corresponding to the layer number;

emitting a first laser beam according to a first molding parameter, and performing laser scanning on a border area of the first part by using the first laser beam;

After controlling the phase angle of the second laser beam to deflect by a first angle, emitting the second laser beam according to a second molding parameter, and performing laser scanning on the first solid filling area by using the second laser beam;

After controlling the phase angle of the third laser beam to deflect by a second angle, emitting the third laser beam according to the third molding parameter, and after laser remelting scanning the first solid filling area by the third laser beam, confirming that the layer processing corresponding to the layer number is completed.

The present invention also provides a laser melting forming system, comprising a controller for executing the above laser melting forming method.

The laser melting forming method and system provided by the present invention, in the laser melting forming method of the present invention, a first layer processing instruction containing the layer number of a part to be processed is received, and a layer of alloy powder of a preset thickness is laid; a first part border area and a first entity filling area corresponding to the layer of alloy powder are determined according to the first layer processing parameters corresponding to the layer number; a first laser beam is emitted according to the first forming parameters, and the first part border area is laser scanned by the first laser beam; after controlling the phase angle of the second laser beam to deflect by a first angle, a second laser beam is emitted according to the second forming parameters, and the first entity filling area is laser scanned by the second laser beam; after controlling the phase angle of the third laser beam to deflect by a second angle, a third laser beam is emitted according to the third forming parameters, and after the first entity filling area is laser remelted and scanned by the third laser beam, it is confirmed that the layer processing corresponding to the layer number is completed.

The present invention performs laser scanning on different areas (such as the first part border area and the first entity filling area) through different molding parameters, which can ensure that the processing requirements of different processing areas are met during the part processing process; and when the first entity filling area of each layer is laser scanned, the phase angle of the second laser beam is deflected by the first angle according to a certain rule, so that the heat distribution during the laser scanning processing is more uniform; at the same time, when the first entity filling area of each layer is laser remelted, the phase angle of the third laser beam is also deflected by the second angle according to a certain rule, so that the heat distribution during the laser remelting scanning is more uniform, and the heat distribution during the laser scanning process is uniform. Evenness can avoid heat accumulation in local areas, make the molten pool have good metallurgical bonding properties, greatly reduce porosity, and make the pore distribution tend to be uniform; at the same time, by laser remelting scanning each layer of alloy powder, it can reduce the defects formed during the first molding, such as holes caused by unmelted particles, and can also make the pores inside the molten pool escape due to heat during the melting process (and, due to the preheating during the first laser scanning, the cooling rate of the molten pool can be significantly reduced, so the bubbles wrapped in the molten pool have more time to escape), so that the porosity of the laser melting parts can be effectively reduced, and the high density of the final molded parts can be achieved, so that the parts meet the required performance requirements. In addition, the present invention has low cost, simple operation (only the laser parameters need to be adjusted to be directly controlled by the controller, without manual processing), and can be used in batches. Therefore, the present invention can promote the widespread application of laser melting molding technology in the automotive industry.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

FIG. 1 is a flow chart of a laser melting forming method according to an embodiment of the present invention.

Detailed ways

The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

In the present invention, a laser melting forming method is provided. As shown in FIG1 , the laser melting forming method comprises the following steps S10-S50:

S10, receiving a first layer processing instruction including a layer number of a part to be processed, and laying a layer of alloy powder of a preset thickness; it can be understood that the part to be processed includes a processing layer with a preset total number of processing layers. The layer number refers to the number of layers corresponding to one of the total number of processing layers of the part to be processed. In the present invention, it is first necessary to process the processing data of the part to be processed, for example, the determination of the total number of processing layers and the pre-determination and storage of the first layer processing parameters associated with each layer number.

Furthermore, the layer of alloy powder with a preset thickness includes: controlling the powder spreading device to spread a layer of alloy powder, and controlling the scraper to scrape the layer of alloy powder so that the thickness of the layer of alloy powder is equal to the preset thickness. That is, before the layer processing corresponding to each layer number starts, a layer processing instruction containing the layer number (such as the first layer processing instruction mentioned above) will be generated to indicate the start of layer processing of the processing layer corresponding to the layer number. After the controller receives the layer processing instruction, it will control the powder spreading device (such as the upper and lower powder spreading device) to start spreading a layer of alloy powder particles, and control the scraper to scrape the layer of alloy powder so that its thickness reaches the preset thickness. Preferably, the preset thickness is 30 to 200 μm. In a specific embodiment, the preset thickness is 50 μm, and the alloy powder is aluminum alloy (such as cast aluminum alloy AlSi10Mg) powder. The alloy powder particles are prepared by gas atomization.

S20, determining the first part border area and the first entity filling area corresponding to the layer of alloy powder according to the first layer processing parameters corresponding to the layer number; it is understandable that the position of the first part border area includes the outer border and the inner border corresponding to the part to be processed in the processing layer corresponding to the above-mentioned layer number; and the first entity filling area refers to other areas in the processing layer that need to be laser scanned and processed except the first part border area. It is understandable that the positions of the first part border area and the first entity filling area corresponding to each processing layer can be the same or different. Therefore, it is necessary to retrieve the pre-stored first layer processing parameters according to the layer number in the first layer processing instruction, in which the positions of the first part border area and the first entity filling area in the processing layer corresponding to the layer number are marked.

When laser melting forming is performed on the part to be processed in the present invention, the forming processing parameters and laser processing methods for the first part border area and the first solid filling area of the part to be processed may be different (the same applies to each processing layer and will not be repeated in the present invention), thereby achieving different processing effects; for example, in the subsequent step S30, the first part border area is subjected to a unidirectional laser scan using the first forming parameter, which is mainly used to improve the roughness of the outer surface of the part to be processed; and in the subsequent steps S40 and S50, the first solid filling area is laser scanned and laser remelted using the second forming parameter and the third forming parameter, respectively, so that the temperature field of the part to be processed during the processing can be evenly distributed, heat accumulation in local areas can be avoided, and the generation of pores can be reduced, thereby improving the density of the final processed part to be processed.

S30, emitting a first laser beam according to the first forming parameter (wherein the first laser beam can be emitted by a first laser), and performing laser scanning on the first part border area by the first laser beam; further, the scanning mode of the first laser beam for laser scanning the first part border area is unidirectional scanning (other scanning modes can also be selected according to requirements); understandably, the above-mentioned first forming parameters mainly include laser power, laser scanning speed, etc., which can be determined according to the type of alloy powder and the state of the alloy powder. Understandably, the first forming parameters corresponding to each processing layer can be the same or different. Preferably, the first forming parameters include: the value range of the laser scanning speed is: 200mm/s～1600mm/s; the value range of the laser power is: 200W～1000W; the value range of the scanning spacing is: 20～2000μm; the value range of the defocus amount is: 0.1～3mm; the value range of the circulating air volume is: 0～80m ³ /H. In a specific embodiment, the laser scanning speed is 300 mm/s; the laser power is 275 W; the scanning interval is 150 μm; the defocus is 0.1 mm; and the circulating air volume is 55 m3/H. It can be understood that the above-mentioned one-way laser scanning of the first part frame area by the first molding parameter is mainly used to improve the roughness of the outer surface of the part to be processed.

S40, after controlling the phase angle of the second laser beam (wherein the second laser beam can be emitted by the second laser) to deflect by the first angle, the second laser beam is emitted according to the second forming parameter, and the first entity filling area is laser scanned by the second laser beam; understandably, the alloy powder used in the present invention is prepared by gas atomization. In the process of preparing alloy powder by gas atomization, due to the extremely fast cooling speed, the complex airflow easily causes the metal droplets to surround the gas, and under the condition of rapid cooling and solidification, the gas is locked into the particles to form hollow powder. During the processing, the gas inside these powder particles will eventually accumulate in the molded parts to be processed to form pores; and in the process of processing the processing layer corresponding to the layer number, as the laser scanning is carried out, heat accumulation will occur, the molten pool temperature, the molten pool liquid phase time and the molten pool size will all show an increasing trend, and the cooling rate will show a decreasing trend. When the molten pool temperature is relatively low, the evaporated metal vapor and argon gas have a low solid solubility in the molten pool, and the solute cools and solidifies rapidly to form a relatively small number of pores. However, when the molten pool temperature is high, the gas solubility also increases accordingly. Under longer liquid phase time and relatively smaller cooling rate, the violent molten pool convection causes the dissolved gas to precipitate. These pores may merge and escape with each other. As the molten pool cools and solidifies, more pores precipitate and remain in the molten pool, eventually forming more metallurgical pores. In the process of laser scanning each processing layer layer by layer, if a fixed laser scanning method is used for each processing layer, for example, the laser phase angle of the laser scanning is the same, the heat generated by the laser scanning will be unevenly distributed and concentrated in local areas, resulting in greater stress inside the parts and causing deformation and other problems. It is also not conducive to the uniform overflow of bubbles (so that the holes will be unevenly distributed, the size of the pores will be increased, and the number of pores will increase). To avoid the above situation, in the present invention, before laser scanning each processing layer, the laser phase angle of the second laser beam will first be deflected by a first angle according to a preset rule (for example, deflected in the same direction each time). In this way, the temperature field of the parts to be processed during the laser scanning process can be evenly distributed (heat distribution is uniform), heat accumulation in local areas can be avoided, the generation of pores can be reduced, and the size of the gaps can be reduced, thereby improving the density of the parts to be processed.

Preferably, the first angle of the laser phase angle deflection of the second laser beam is not an integer divisible by 360. That is, the first angle of the specific deflection can be adjusted according to the actual situation (further, the first angle is greater than 0° and less than 180°), but the main principle is to minimize the repetition rate of the laser phase angle at the same angle that may be repeated. For example, the angle of clockwise deflection is 90° each time. At this time, when the laser phase angle of the first layer is 0°, the fifth layer will be 0° again. Therefore, the first angle of 90° will not be suitable. Therefore, preferably, the angle value of the first angle is not an integer divisible by 360 degrees. For example, the first angle is preferably a prime number in the range of 50° to 90° (not an integer divisible by 360 degrees). For example, the first angle can be 57°, 67°, etc. Specifically, the deflection of the laser phase angle of the second laser beam can be achieved through the XY-axis galvanometer of the second laser, that is, after the second laser beam is incident on the XY-axis galvanometer, the reflection angle of the galvanometer is controlled by a controller, so that the two galvanometers can scan along the X and Y axes respectively, thereby achieving the first angle of laser beam deflection.

It is understandable that in the present invention, the first laser and the second laser can be the same laser or two different lasers (or two laser heads arranged on the same laser, etc.). Among them, the way in which the second laser beam performs laser scanning on the first entity filling area can be set according to demand. For example, the way in which the second laser beam performs laser scanning on the first entity filling area is preferably raster scanning or partition scanning; wherein, the raster length of the raster scanning, the partition length and partition form of the partition scanning, etc. can be set according to actual needs. It is understandable that the above-mentioned second forming parameters mainly include laser power, laser scanning speed, partition border overlap (overlapping part of adjacent molten pools), etc., which can be determined according to the type of alloy powder and the state of the alloy powder. It is understandable that the second forming parameters corresponding to each processing layer can be the same or different. Further, the second molding parameters include: the laser scanning speed has a value range of 200mm/s to 1600mm/s; the laser power has a value range of 200W to 1000W; the scanning spacing has a value range of 20 to 2000μm; the defocus value has a value range of 0.1 to 3mm; the partition frame overlap value range is 40 to 80μm; the circulating air volume has a value range of 0 to ^80m3 /H. In a specific embodiment, the second molding parameters include: laser scanning speed of 1400mm/s; laser power of 400W; scanning spacing of 150μm; partition frame overlap value (overlapping portion of adjacent molten pools) of 60μm; defocus value of 2.5mm; circulating air volume of 55m3/H.

S50, after controlling the phase angle of the third laser beam (wherein the third laser beam can be emitted by the third laser) to deflect by the second angle, the third laser beam is emitted according to the third forming parameter, and after the laser remelting scan of the first solid filling area is performed by the third laser beam, it is confirmed that the layer processing corresponding to the layer number is completed. It can be understood that in the laser melting forming process, as the processing height continues to increase, the higher molten pool depth will produce a larger heat-affected zone, which will have a significant preheating effect on the previously solidified processing layer, causing the retained pores to expand and become larger. As the heat continues to accumulate, the maximum temperature of the molten pool becomes higher and higher. Under the thermal shock of the laser, the alloy powder forms a deeper molten pool, and a large amount of metal is vaporized. When the laser is turned off, a large recoil pressure is formed. Under the action of the recoil pressure, most of the metal liquid flows to the center of the molten pool, forming a closed lock hole at the bottom of the molten pool. In this process, the metal vapor will be captured by the solidification front to form a nearly circular lock hole; under the subsequent heat action, these pores will expand and become larger, and even float up and escape under the action of the buoyancy effect. Therefore, in the present invention, after the processing layer is laser scanned by the second laser beam in step S40 so that the single-layer cross-section is formed, it is necessary to perform a secondary laser remelting scan in step S50 to reduce defects formed during the first forming, such as holes caused by unmelted particles, and the pores inside the molten pool can be heated and escaped during the melting process (and, due to the preheating during the first laser scanning, the cooling rate of the molten pool can be significantly reduced, so the bubbles wrapped in the molten pool have more time to escape), so that the pores inside the molten pool can be heated and escaped during the melting process, reducing the porosity and evenly distributing the heat, thereby avoiding deformation caused by large stress inside the parts.

In this embodiment, the laser scanning path of remelting is the same as the first laser scanning path (the path of laser scanning by the second laser beam in step S40), but before laser remelting scanning is performed on each processing layer, the laser phase angle of the third laser beam is first deflected by a second angle according to a preset rule (for example, deflecting in the same direction each time). In this way, the temperature field distribution of the part to be processed during the laser scanning process can be uniform (heat distribution is uniform), heat accumulation in local areas can be avoided, the generation of pores can be reduced, and the size of the voids can be reduced, so that the pore distribution tends to be uniform. During the laser remelting process, the pores inside the molten pool can be heated and escaped during the melting process, so that the molten pool has good metallurgical bonding and the porosity is greatly reduced. At the same time, due to the preheating of the first scan (laser scanning by the second laser beam in step S40), the cooling rate of the molten pool is significantly reduced, and the bubbles wrapped in the molten pool have enough time to escape, thereby obtaining a high-density part to be processed.

Preferably, the second angle of the laser phase angle deflection of the third laser beam is not an integer divisor of 360. That is, the specific second angle of deflection can be adjusted according to the actual situation (further, the second angle is greater than 0° and less than 180°), but its main principle is to minimize the repetition rate of the laser phase angle at the same angle that may be repeated. Therefore, preferably, the angle value of the second angle is not an integer divisor of 360 degrees. For example, the second angle is preferably a prime number in the range of 50° to 90° (not an integer divisor of 360 degrees). For example, the second angle is 57°, 67°, etc. It can be understood that the second angle can be the same as or different from the above-mentioned first angle. Specifically, the deflection of the phase angle of the third laser beam of the laser can be achieved by the XY axis galvanometer of the third laser, that is, after the third laser beam is incident on the XY axis galvanometer, the reflection angle of the galvanometer is controlled by the controller, so that the two galvanometers can be scanned along the X and Y axes respectively, thereby achieving the second angle of laser beam deflection.

In the present invention, the third laser and the second laser can be the same laser or two different lasers (or two laser heads arranged on the same laser, etc.). Thus, the three lasers can be divided into the following cases:

When the third laser and the first laser and the second laser are different lasers, each deflection of the phase angle of the third laser beam is not associated with the laser phase angle of the second laser beam or the second laser beam, that is, the phase angles of the three laser beams are adjusted independently, and in step S40, the first angle is adjusted only based on the phase angle of the second laser beam that finally corresponds to the previous processing layer; in step S50, the second angle is adjusted only based on the phase angle of the third laser beam that finally corresponds to the previous processing layer.

When the second laser and the third laser are the same laser (they are not the same laser as the first laser), each deflection of the phase angle of the third laser beam is associated with the laser phase angle of the second laser beam, and each deflection of the phase angle of the second laser beam is also associated with the laser phase angle of the third laser beam; that is, in step S40, the present layer (the processing layer corresponding to the layer number) adjusts the first angle based on the phase angle of the third laser beam (that is, the second laser beam) finally corresponding to the previous processing layer; in step S50, the second angle is adjusted based on the laser phase angle of the second laser beam (that is, the third laser beam) after the laser scanning in the above step S40 is completed in the present layer (that is, based on the phase angle after being deflected by the first angle). Understandably, when the third laser and the second laser are the same laser, the adjustment of the laser phase angle is performed continuously, that is, first, the phase angle of the laser beam is deflected by a first angle in step S40 (for example, the laser phase angle is deflected from the first angle of 0° to 57°), and then, in step S50, the laser phase angle is further deflected by a second angle on this basis (for example, after the laser phase angle is deflected from 57° to the second angle of 67°, the laser phase angle is 124°). Further, when the third laser and the second laser are the same laser, at this time, the sum of the angle values of the first angle and the second angle is not an integer divisor of 360, so as to ensure that the repetition rate of the laser phase angle at the same angle is low. Understandably, the above-mentioned deflection of the phase angle of the continuous association between the phase angles of the previous processing layer and the current layer can achieve uniform heat distribution. In addition, while making the heat evenly distributed, it can also avoid problems such as deformation caused by large stress inside the parts.

When the first laser, the second laser and the third laser are the same laser, the deflections of the phase angles of the laser beams of the three lasers are interrelated; that is, in step S40, the first angle is adjusted based on the laser phase angle of the first laser beam (that is, the second laser beam) after the laser scanning of step S30 is completed in the present layer (the processing layer corresponding to the layer number). In step S50, the second angle is adjusted based on the laser phase angle of the second laser beam (that is, the third laser beam) after the laser scanning of step S40 is completed in the present layer (that is, based on the phase angle after the first angle has been deflected).

When the third laser is the same laser as the first laser (not the same laser as the second laser), each deflection of the phase angle of the third laser beam is associated with the laser phase angle of the first laser beam, but is not associated with the laser phase angle of the second laser beam; that is, in step S40, the first angle is adjusted only on the basis of the phase angle of the second laser beam that finally corresponds to the previous processing layer. In step S50, the second angle is adjusted on the basis of the laser phase angle of the first laser beam (that is, the third laser beam) after the laser scanning in step S30 is completed in the current layer (the processing layer corresponding to the layer number).

When the second laser is the same laser as the first laser (and not the same laser as the third laser), each deflection of the phase angle of the second laser beam is associated with the laser phase angle of the first laser beam, but is not associated with the laser phase angle of the third laser beam; that is, in step S40, the first angle is adjusted only on the basis of the laser phase angle of the first laser beam (i.e., the second laser beam) after the laser scanning of step S30 is completed in the current layer (the processing layer corresponding to the layer number). In step S50, the second angle is adjusted only on the basis of the phase angle of the third laser beam finally corresponding to the previous processing layer.

Among them, the method of laser remelting scanning of the first entity filling area by the third laser beam can be set according to the needs, for example, the method of laser remelting scanning of the first entity filling area by the third laser beam is preferably raster scanning or partition scanning; wherein, the raster length of the raster scanning, the partition length and partition form of the partition scanning can be set according to actual needs. Specifically, the method of laser remelting scanning of the first entity filling area by the third laser beam is usually regular polygonal partition scanning, and the width of a single partition is generally 8mm, that is, first, the cross section to be remelted is evenly partitioned according to the actual size of the part to be processed, for example, when the laser phase angle is 124°, the first entity filling area is partitioned along the X direction at 124° according to the size of 80mm*80mm. It is understandable that the above-mentioned third forming parameters mainly include laser power, laser scanning speed, partition frame overlap (adjacent molten pool overlap), etc., which can be determined according to the type of alloy powder and the state of the alloy powder. It is understandable that the third forming parameters corresponding to each processing layer can be the same or different. Further, the third molding parameters include: the laser scanning speed has a value range of 200mm/s to 1600mm/s; the laser power has a value range of 200W to 1000W; the scanning spacing has a value range of 20 to 2000μm; the defocus value has a value range of 0.1 to 3mm; the partition frame overlap value range is 40 to 80μm; the circulating air volume has a value range of 0 to 80m ³ /H. In a specific embodiment, the third molding parameters include: laser scanning speed of 1400mm/s; laser power of 400W; scanning spacing of 150μm; partition frame overlap value of 60μm; defocus value of 2.5mm; circulating air volume of 55m ³ /H. In the above laser remelting scanning process, it is ensured that the remelting lines are evenly distributed, and the remelting lines between the partition areas are connected without disconnection.

In one embodiment, in the step S50, after confirming that the layer corresponding to the layer number is processed, the step further includes:

When it is confirmed that the layer number is equal to the total number of processing layers of the part to be processed, it is confirmed that the processing of the part to be processed is completed. That is, when the layer number is equal to the total number of processing layers of the part to be processed, it means that the part to be processed has been processed. At this time, the laser scanning of all laser beams can be stopped, indicating that the processing of the part to be processed has been completed. When the layer number is less than the total number of processing layers of the part to be processed, it means that the part to be processed has not been processed. At this time, it is necessary to continue to start the layer processing of the next processing layer.

The present invention performs laser scanning on different areas (such as the first part frame area and the first entity filling area) through different molding parameters, which can ensure that the processing requirements of different processing areas are met during the processing of the part to be processed; and when the laser scanning is performed on the first entity filling area of each layer, the phase angle of the second laser beam is deflected by the first angle according to a certain rule, so that the heat distribution during the laser scanning processing is more uniform; at the same time, when the laser remelting scanning is performed on the first entity filling area of each layer, the phase angle of the third laser beam is also deflected by the second angle according to a certain rule, so that the heat distribution during the laser remelting scanning is more uniform, and the laser scanning The uniform heat distribution during the scanning process can avoid the accumulation of heat in local areas, so that the molten pool has good metallurgical bonding properties, greatly reduces the porosity, and the pore distribution tends to be uniform; at the same time, by laser remelting and scanning each layer of alloy powder, the pores inside the molten pool can be heated and escaped during the melting process (and, due to the preheating during the first laser scanning, the cooling rate of the molten pool can be significantly reduced, so the bubbles wrapped in the molten pool have more time to escape), so that the porosity of the laser melting parts to be processed can be effectively reduced, and the high density of the final formed parts to be processed can be achieved, so that the parts to be processed meet the required performance requirements. In addition, the present invention has low cost, simple operation (only the laser parameters need to be adjusted to be directly controlled by the controller, without manual processing), and can be used in batches. Therefore, the present invention can promote the widespread application of laser melting forming technology in the automotive industry.

In one embodiment, in step S50, after confirming that the layer corresponding to the layer number has been processed, the process further includes:

When it is confirmed that the layer number is less than the total number of processing layers of the part to be processed, a second layer processing instruction containing the next layer number is received, and a layer of alloy powder of the preset thickness is laid; wherein the total number of processing layers refers to the total number of layers that need to be processed by laser scanning. When the layer number is less than the total number of processing layers of the part to be processed, it means that the part to be processed has not been processed yet. At this time, it is necessary to continue to start the layer processing of the next processing layer. Among them, the next layer number is the layer number in the total number of processing layers that is adjacent to the layer number in the above step S10 and is located after the layer number. After the controller receives the second layer processing instruction, it instructs to start layer processing of the processing layer corresponding to the next layer number, that is, control the powder laying device to start laying a layer of alloy powder particles, and control the scraper to scrape the layer of alloy powder so that its thickness reaches the preset thickness.

The second part frame area and the second entity filling area corresponding to the layer of alloy powder are determined according to the second layer processing parameters corresponding to the next layer number; the second part frame area position includes the outer frame and the inner frame corresponding to the part to be processed in the processing layer corresponding to the next layer number; and the second entity filling area refers to other areas in the processing layer that need to be laser scanned except the second part frame area. It can be understood that the first part frame area and the first entity filling area can be the same as or different from the second part frame area and the second entity filling area. Therefore, it is necessary to retrieve the pre-stored second layer processing parameters according to the next layer number in the second layer processing instruction.

The first laser beam is emitted according to the first molding parameter, and the second part border area is laser scanned by the first laser beam; further, the first laser beam performs laser scanning on the second part border area (and the part border areas of all other processing layers are the same) in a unidirectional scanning manner; referring to the above content, it can be known that the first molding parameter preferably includes: laser scanning speed 300mm/s; laser power 275W; scanning spacing 150μm; defocus amount 0.1mm; circulating air volume 55m3/H. However, in the present invention, the first molding parameter of each layer can also be changed according to demand, that is, while achieving the improvement of the roughness of the outer surface of the part to be processed, the first molding parameter can also be adjusted to meet different processing requirements.

After controlling the phase angle of the second laser beam to deflect to the first angle, the second laser beam is emitted according to the second molding parameter, and the second solid filling area is laser scanned by the second laser beam; that is, before laser scanning the processing layer corresponding to the next layer number, the laser phase angle of the second laser beam is first deflected to the first angle according to a preset rule (for example, deflected in the same direction each time), so that the temperature field distribution (heat distribution) of the part to be processed during the laser scanning process can be uniform, avoiding heat accumulation in local areas, reducing the generation of pores, and reducing the size of the gaps, thereby improving the density of the part to be processed. In the present invention, in order to meet different processing requirements, the second molding parameters of each layer can also be adjusted according to the requirements.

After controlling the phase angle of the third laser beam to deflect by a second angle, emitting the third laser beam according to the third molding parameter, and after laser remelting scanning the first solid filling area by the third laser beam, confirming that the layer processing corresponding to the next layer number is completed; that is, after the cross-section of the processed layer corresponding to the next layer number is formed by laser scanning by the second laser beam in the above steps, it is necessary to continue the secondary laser remelting scanning in this step so that the pores inside the molten pool can escape due to heat during the melting process, thereby reducing the porosity. In this embodiment, the laser scanning path of remelting is the same as the path of laser scanning by the second laser beam, but the laser phase angle of the third laser beam is deflected by the second angle according to a preset rule (for example, deflected in the same direction each time), so that the temperature field distribution of the part to be processed during the laser scanning process can be uniform (heat distribution is uniform), avoiding heat accumulation in local areas, reducing the generation of pores, and reducing the size of the voids, so that the pore distribution tends to be uniform. During the laser remelting process, the pores inside the molten pool can be heated and escaped during the melting process, so that the molten pool has good metallurgical bonding and the porosity is greatly reduced. At the same time, due to the preheating of laser scanning by the second laser beam, the cooling rate of the molten pool is significantly reduced, and the bubbles wrapped in the molten pool have enough time to escape, thereby obtaining a high-density part to be processed. In the present invention, in order to meet different processing requirements, the third molding parameters of each layer can also be adjusted according to the requirements.

When it is confirmed that the next layer number is equal to the total number of layers of the part to be processed, it is confirmed that the part to be processed has been processed. That is, when the next layer number is equal to the total number of layers of the part to be processed, it means that the part to be processed has been processed. At this time, the laser scanning of all laser beams can be stopped, indicating that the part to be processed has been processed.

In one embodiment, a laser melting forming system is provided, comprising a controller for executing the above-mentioned laser melting forming method. It is understandable that the above-mentioned controller is installed in the laser melting forming system. For the specific definition of the controller, please refer to the definition of the laser melting forming method above, which will not be repeated here. Each module in the above-mentioned controller can be implemented in whole or in part by software, hardware and a combination thereof. The above-mentioned modules can be embedded in or independent of the laser melting forming system in the form of hardware, or can be stored in a storage device in the laser melting forming system in the form of software, so as to be called to perform the operations corresponding to the above-mentioned modules.

The technicians in the relevant field can clearly understand that the internal structure of the controller can be divided into different functional units or modules according to the needs to complete all or part of the functions described above. The above-mentioned embodiments are only used to illustrate the technical solution of the present invention, not to limit it; although the present invention is described in detail with reference to the above-mentioned embodiments, the ordinary technicians in the field should understand that: it is still possible to modify the technical solutions recorded in the above-mentioned embodiments, or to replace some of the technical features therein by equivalent; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the protection scope of the present invention.

Claims (9)

1. A laser melting forming method, characterized by comprising: Receiving a first layer processing instruction including a layer number of a part to be processed, and laying a layer of alloy powder with a preset thickness; the preset thickness is 30 to 200 μm; the alloy powder is aluminum alloy powder; Determine a first part frame area and a first entity filling area corresponding to the layer of alloy powder according to the first layer processing parameters corresponding to the layer number; emitting a first laser beam according to a first molding parameter, and performing laser scanning on a border area of the first part by using the first laser beam; After controlling the phase angle of the second laser beam to deflect by a first angle, emitting the second laser beam according to a second molding parameter, and performing laser scanning on the first solid filling area by the second laser beam; the first angle range is 0 to 180 degrees, and the first angle is not an integer divisor of 360 degrees; After controlling the phase angle of the third laser beam to deflect by a second angle, emitting the third laser beam according to the third molding parameter, and after laser remelting scanning the first solid filling area by the third laser beam, confirming that the layer processing corresponding to the layer number is completed. 2. The laser melting forming method according to claim 1, characterized in that after confirming that the layer corresponding to the layer number is processed, it also includes: When it is confirmed that the layer number is less than the total number of processing layers of the part to be processed, receiving a second layer processing instruction containing the next layer number, and laying a layer of alloy powder with the preset thickness; Determine a second part frame area and a second entity filling area corresponding to the layer of alloy powder according to the second layer processing parameters corresponding to the next layer number; emitting a first laser beam according to a first molding parameter, and performing laser scanning on a border area of the second part by using the first laser beam; After controlling the phase angle of the second laser beam to deflect by a first angle, emitting the second laser beam according to a second molding parameter, and performing laser scanning on the second solid filling area by the second laser beam; After controlling the phase angle of the third laser beam to deflect by the second angle, emitting the third laser beam according to the third molding parameter, and performing laser remelting scanning on the first solid filling area by the third laser beam, confirming that the layer corresponding to the next layer number is processed; When it is confirmed that the next layer number is equal to the total number of processing layers of the part to be processed, it is confirmed that the processing of the part to be processed is completed. 3. The laser melting forming method according to claim 2, characterized in that after confirming that the layer corresponding to the layer number is processed, it also includes: When it is confirmed that the layer number is equal to the total number of processing layers of the part to be processed, it is confirmed that the processing of the part to be processed is completed. 4. The laser melting forming method according to claim 1, wherein the first forming parameter comprises: The laser scanning speed range is: 200mm/s～1600mm/s; The laser power range is: 200W～1000W; The scanning interval ranges from 20 to 2000 μm. The range of defocus value is: 0.1～3mm; The range of circulating air volume is: 0～80m ³ /H. 5. The laser melting forming method according to claim 1, wherein the second forming parameter comprises: The laser scanning speed range is: 200mm/s～1600mm/s; The laser power range is: 200W～1000W; The scanning interval ranges from 20 to 2000 μm. The range of defocus value is: 0.1～3mm; The value range of the partition border overlap is: 40～80μm; The range of circulating air volume is: 0～80m ³ /H. 6. The laser melting forming method according to claim 1, wherein the third forming parameter comprises: The laser scanning speed range is: 200mm/s～1600mm/s; The laser power range is: 200W～1000W; The scanning interval ranges from 20 to 2000 μm. The range of defocus value is: 0.1～3mm; The value range of the partition border overlap is: 40～80μm; The range of circulating air volume is: 0～80m ³ /H. 7. The laser melting forming method according to claim 1, characterized in that the first laser beam performs laser scanning on the first part border area in a unidirectional scanning manner; the second laser beam performs laser scanning on the first solid filling area in a raster scanning manner or a partition scanning manner; The third laser beam performs laser remelting scanning on the first solid filling area in a raster scanning or partition scanning manner. 8. The laser melting forming method according to claim 1, wherein laying a layer of alloy powder with a preset thickness comprises: The powder spreading device is controlled to spread a layer of alloy powder, and the scraper is controlled to scrape the layer of alloy powder so that the thickness of the layer of alloy powder is equal to a preset thickness. 9. A laser melting forming system, characterized by comprising a controller for executing the laser melting forming method according to any one of claims 1 to 8.