Laser wire feeding additive manufacturing method and device
Through laser head annular spot and negative defocus technology, combined with the vision camera system and laser power-time gradient control, the problem of wire breakage and deviation in laser wire feed additive manufacturing is solved, and efficient and uniform product manufacturing is achieved.
Patent Information
- Application Number
- CN202510521654.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-24
- Publication Date
- 2025-07-04
- Estimated Expiration
- Not applicable · inactive patent
AI Technical Summary
In laser wire feed additive manufacturing, the high flowability of molten metal makes it difficult to ensure the dimensional accuracy of the molded parts, and the wire is prone to breaking and deviating from position, affecting production efficiency and product quality.
The laser head annular spot and negative defocus technology are used to control the center position of the wire material, and the laser power and wire feeding rate are adjusted through the visual camera system detection. The laser power-time gradient phased control strategy is adopted to ensure the stable wire feeding and dynamic balance of the melt pool of the wire material.
It improves production efficiency, ensures that the product has uniform shape and is defect-free, and greatly improves the large-scale application potential of laser wire feed additive manufacturing.
Smart Images
Figure CN120244255A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to laser processing, and specifically to a laser wire feeding additive manufacturing method and device. Background Art
[0002] With the improvement of production technology, the requirement for production efficiency is also getting higher and higher. Laser additive manufacturing, also known as "3D" printing, is a technology that directly manufactures solid parts from digital models by means of layer-by-layer stacking. Compared with traditional manufacturing technologies, laser additive manufacturing technology has the advantages of simplified process flow, short production cycle, high material utilization rate, etc., and can significantly reduce the production cost. The material supply methods for additive manufacturing mainly include powder and wire. Among them, wire has characteristics such as a material utilization rate of ≥95%, no need for a vacuum environment, high density of the formed part, and simplified post-treatment process, and can be directly applied to industry. It is regarded as a more promising choice with great development and application prospects.
[0003] However, the laser wire feeding additive manufacturing technology still faces multiple challenges in practical applications. During the actual production process of laser wire feeding additive manufacturing, after the wire is heated by the laser, the high fluidity of the molten metal makes it difficult to guarantee the dimensional accuracy of the formed part; moreover, the wire is prone to breakage during the laser heating process, resulting in the subsequent production stoppage; in addition, due to the certain flexibility of the wire, during the wire feeding process, the wire is prone to deviate from its position, resulting in the deviation of the wire feeding path and poor additive effect. These problems seriously restrict the large-scale industrial application of this technology, and there is an urgent need for technological breakthroughs and continuous improvement of processing and debugging methods. Summary of the Invention
[0004] The purpose of the present invention is to provide a laser wire feeding additive manufacturing method and device, which can at least solve some defects in the prior art.
[0005] To achieve the above purpose, the embodiments of the present invention provide the following technical solution: A laser wire feeding additive manufacturing method, comprising the following steps:
[0006] Set the wire at the central position of the wire feeding nozzle, and adjust the focus of the laser head to be below the surface of the substrate;
[0007] Control the end of the wire to move to the surface of the substrate;
[0008] The laser head processes a molten pool on the surface of the substrate and continuously feeds wire into the molten pool;
[0009] And when the material in the molten pool reaches the set value, withdraw the wire to a certain distance above the substrate.
[0010] Further, the relative distance between the center of the wire and the center of the wire feeding nozzle is detected by a vision camera system, and when the detected relative distance is within a set range, it is determined that the wire is located at the center position of the wire feeding nozzle.
[0011] Further, a detection plate is placed on the surface of the substrate, the laser head is controlled to move along the optical axis direction, and when the outer diameter of the annular light spot on the detection plate is the smallest, this is the focal position of the laser;
[0012] The laser head is controlled to move downward so that the focus of the laser is below the surface of the substrate.
[0013] Further, during the light emission process of the laser head, the laser power and the wire feeding rate are adjusted according to the light emission time.
[0014] Further, a molten pool is processed on the surface of the substrate with a first laser power, and the wire is fed into the molten pool at a first wire feeding rate;
[0015] And when a certain amount of wire is reached in the molten pool, the molten pool is irradiated with a second laser power, and the wire is fed at a second wire feeding rate, and the second laser power is less than the first laser power, and the second wire feeding rate is less than the first wire feeding rate.
[0016] Further, when the end of the wire moves to the surface of the substrate, the laser head first heats the surface of the substrate with a third laser power, the wire is fed at a third wire feeding rate, and after a certain period of time, the laser head processes the molten pool with a first laser power; the third wire feeding rate is less than the second wire feeding rate, the third laser power is less than the first laser power, and is greater than the second laser power.
[0017] Further, when the laser head works at the second laser power for a preset time, it is adjusted to a fourth laser power, and the wire is fed at a fourth wire feeding rate; the fourth laser power is less than the second laser power, and the fourth wire feeding rate is less than the second wire feeding rate.
[0018] Further, when the end of the wire contacts the surface of the substrate, the wire and the substrate form a circuit conduction to control the laser head to emit light to the substrate.
[0019] Further, when the wire is withdrawn, the wire is melted with a fifth laser power, and the molten pool is kept warm with the fifth laser power.
[0020] The present invention provides another embodiment, a laser wire feeding additive manufacturing device, comprising:
[0021] A laser, which processes a molten pool on a substrate and keeps the molten pool warm;
[0022] A wire feeding mechanism that continuously feeds wire into the molten pool and withdraws the wire when the material in the molten pool reaches a set value;
[0023] A control unit that adjusts the laser power of the laser and the wire feeding rate of the wire feeding mechanism according to the light emission time.
[0024] Compared with the prior art, the beneficial effects of the present invention are as follows: The laser head uses an annular light spot, the wire is arranged at the center position of the wire feeding nozzle, and at the same time, the focus of the laser head is adjusted to be below the surface of the substrate, so as to ensure that the wire can smoothly pass through the center of the annular light spot, so that wire breakage does not occur during the additive manufacturing process.
[0025] During laser wire feeding additive manufacturing, the laser heats the substrate to form a molten pool. The wire feeding mechanism continuously feeds wire into the molten pool, and adjusts the laser power and the wire feeding rate according to the working time of the laser head. The total time only needs 3 s to additively manufacture a cylindrical structure product with a diameter of 3 mm and a height of 4 mm on the substrate, which greatly improves the production efficiency, and the morphology of the additively manufactured product is uniform and defect-free. Description of the Drawings
[0026] Figure 1 It is a schematic flow chart of the laser wire feeding additive manufacturing method provided by an embodiment of the present invention;
[0027] Figure 2 It is a detection schematic diagram of the vision camera system of the laser wire feeding additive manufacturing method provided by an embodiment of the present invention;
[0028] Figure 3 It is a schematic diagram of the position of the focus of the laser head and the substrate of the laser wire feeding additive manufacturing method provided by an embodiment of the present invention;
[0029] Figure 4 It is a relationship diagram of the laser power, wire feeding rate and time of the laser wire feeding additive manufacturing method provided by an embodiment of the present invention;
[0030] Figure 5 It is a product photo after the laser wire feeding additive manufacturing method provided by an embodiment of the present invention is prepared. Detailed Embodiments
[0031] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present invention.
[0032] See Figures 1 - 5, an embodiment of the present invention provides a laser wire feeding additive manufacturing method for additive manufacturing of a product on a substrate 3 by a laser, which specifically includes the following steps:
[0033] Adjust the position of the wire 2 at the wire feeding nozzle of the wire feeding mechanism so that the center of the wire 2 is located at the center position of the wire feeding nozzle. Thus, only by adjusting the position of the wire feeding nozzle, it can be ensured that the wire 2 is transported to the specified position on the substrate 3. Additionally, adjust the focus 5 position of the laser head 1 of the laser so that the focus 5 of the laser head 1 is located below the surface of the substrate 3. For the laser head 1, it can generate an annular light spot, that is, use the annular light spot to melt the wire 2 on the substrate 3 to achieve the purpose of additive manufacturing.
[0034] Before the laser head 1 works, feed the wire through the wire feeding mechanism so that the end of the wire 2 moves to the surface of the substrate 3. Specifically, first, the wire feeding mechanism feeds the wire 2 from the wire feeding nozzle at a relatively fast speed, such as 5000 mm / min, to save the entire production time, make the wire feeding process smoother, and last for 100 ms. Then the wire feeding speed is reduced to 450 mm / min and lasts for 2000 ms to make the wire 2 approach the substrate 3 more slowly, avoiding the wire 2 being fed out too much and hitting the substrate 3 in advance due to the too fast speed of the wire 2 and the insufficient reaction speed of the wire feeding mechanism, resulting in the deviation of the position of the wire 2.
[0035] When the end of the wire 2 moves to the specified position on the substrate 3, the laser head 1 of the laser starts to work, and a molten pool is processed on the surface of the substrate 3. The wire feeding mechanism continuously feeds the wire into the molten pool, and the wire 2 melts in the molten pool. The substrate 3 and the wire 2 for laser additive manufacturing are of the same material, such as both being stainless steel with the grade of 304. Usually, the thickness of the substrate 3 can be 4 mm, and the diameter of the wire 2 is 1.2 mm.
[0036] And when the melted wire 2 in the molten pool reaches the set value, the wire 2 is withdrawn to a certain distance above the substrate 3. Determine the amount of material in the molten pool by the wire feeding amount of the wire feeding mechanism, that is, only by the wire 2 rate and the wire feeding time can the set value of the wire 2 in the molten pool be determined. The emitted light of the laser head 1 fuses the wire 2, and the wire 2 is withdrawn from the molten pool. The set value of the wire 2 in the molten pool is determined according to the size of the additive manufactured product. For example, when the product size is relatively small, the set value can be the material required for the entire product, and when the product size is relatively large, the product needs to be layered during additive manufacturing, and the set value is the material required for the corresponding layer.
[0037] In this embodiment, the laser head 1 has an annular light spot, and the focus 5 of the laser head 1 is adjusted to be below the surface of the substrate 3, in a negative defocus state, which can make the inner diameter of the annular light spot of the laser head 1 on the surface of the substrate 3 larger than the outer diameter of the wire 2, and the wire 2 can stably pass through the center of the annular light spot, so that no wire breakage occurs during the additive manufacturing process.
[0038] In a preferred embodiment, a visual method is adopted to detect the position of the wire 2 and the wire feeding nozzle. Specifically, the centers of the wire 2 and the wire feeding nozzle are detected by a visual camera system 4, and then the relative distance between the two centers can be calculated. When the detected relative distance is within the set range, it can be determined that the wire 2 is located at the center position of the wire feeding nozzle. In this embodiment, the visual camera system 4 adopts two cameras and two light sources. The cameras and the light sources are in one-to-one correspondence, and the two cameras are orthogonally installed with a viewing angle of 90 degrees. One camera cooperates with the corresponding light source to locate the center of the wire feeding nozzle and can take pictures of the wire 2 in the X direction, and can obtain the center position of the wire feeding nozzle in real time. The other camera cooperates with the corresponding light source to locate the center of the wire 2 and can take pictures of the wire 2 in the Y direction, and can obtain the center position of the wire 2 in real time, improving the position accuracy of the additive manufacturing wire 2 and the stability and consistency of the processing process, and solving the problems in actual production. Based on the diameter of the wire 2 of 1.2 mm, the set range of the relative distance between the center of the wire 2 and the center of the wire feeding nozzle can be 0.2 mm. It can be preset first. When the relative distance value between the wire 2 and the wire feeding nozzle detected by the visual camera exceeds the set range value of 0.2 mm, an alarm is triggered and the processing is paused. At the same time, the position of the wire 2 can be conveniently adjusted by using the visual camera system 4. Maintenance personnel can optimize the deviation within 0.05 mm with the help of visual feedback so that the relative distance value between the center of the wire 2 and the center of the wire feeding nozzle is within the set range value. Thus, even if the wire 2 has a slight deviation during each wire feeding process, it can be ensured that the relative distance value between the center of the wire 2 and the center of the wire feeding nozzle does not exceed the set range value of 0.2 mm.
[0039] In one embodiment, when adjusting the position of the focus 5 of the laser head 1, a detection plate is placed on the surface of the substrate 3 first. The laser head 1 forms an annular light spot on the detection plate. The laser head 1 is controlled to move along the optical axis direction, which is the vertical direction. The outer diameter of the annular light spot on the detection plate changes. And when the outer diameter of the annular light spot on the detection plate is the smallest, it indicates that the laser focus 5 of the laser head 1 is located on the detection plate. In this embodiment, the detection plate is a 1-mm-thick stainless steel plate. The laser acts on the stainless steel plate to form an annular light spot. A microscope is used to detect the outer diameter of the annular light spot. The electric Z-axis is moved. The electric Z-axis drives the laser head 1 to move vertically. The step accuracy is 0.5 mm. The annular light spot is successively excited to act on the stainless steel plate and its outer diameter is measured. And when the diameter of the annular light spot is the smallest, the corresponding position is the laser focusing focus 5. Continuing to control the electric Z-axis to drive the laser head 1 to move vertically downward so that the laser focus 5 is below the surface of the substrate 3, which is the negative defocus state, then the wire 2 can smoothly pass through the center of the annular light spot. Preferably, the inner diameter of the annular light spot formed by the laser on the substrate 3 is 1.5 - 3.0 mm, which is related to the diameter of the wire 2. When the inner diameter of the annular light spot formed by the laser on the substrate 3 is less than or equal to 1.4 mm, since the diameter of the wire 2 is 1.2 mm, when the wire 2 has a slight deviation and the relative distance from the wire feeding nozzle exceeds the set value of 0.2 mm, the wire 2 will block the light, which will lead to the instability of the laser additive manufacturing process. And when the inner diameter of the annular light spot formed by the laser on the substrate 3 is greater than or equal to 3.0 mm, since the annular light spot on the substrate 3 is larger and the energy is more dispersed, a higher laser energy input is required to form a molten pool on the stainless steel substrate 3. And a larger laser energy input will cause a larger thermal deformation of the stainless steel substrate 3 and a larger heat affected zone of the molten pool, which cannot meet the actual production requirements.
[0040] In the preferred solution, when the laser head 1 emits light, the laser power and the wire feeding rate are adjusted according to the light emission time. The laser power-time gradient staged power control strategy can be adopted for laser wire feeding additive manufacturing to achieve the dynamic balance of the molten pool and ensure that the formed surface is flat and defect-free.
[0041] Specifically, the molten pool is processed on the surface of the substrate 3 with the first laser power, and the wire 2 is fed into the molten pool at the first wire feeding rate. And when a certain amount of the wire 2 is in the molten pool, the molten pool is irradiated with the second laser power, and the wire 2 is fed at the second wire feeding rate. And the second laser power is less than the first laser power, and the second wire feeding rate is less than the first wire feeding rate. In this embodiment, since the absorption rate of the metal material for the laser increases with the increase of temperature, when a certain amount of the wire 2 is in the molten pool, the laser power of the laser head 1 and the wire feeding rate of the wire feeding mechanism are reduced.
[0042] Preferably, before processing the molten pool with the first laser power, the laser head 1 processes the surface of the substrate 3 with the third laser power. That is, when the end of the wire 2 moves to the surface of the substrate 3, the laser head 1 first heats the surface of the substrate 3 with the third laser power. At this time, the wire 2 is fed at the third wire feeding rate. And after a period of time, the laser head 1 processes the molten pool with the first laser power. Specifically, the third wire feeding rate is less than the second wire feeding rate, the third laser power is less than the first laser power, and greater than the second laser power. In this embodiment, since both the wire 2 and the substrate 3 are made of metal, when the end of the wire 2 contacts the surface of the substrate 3, an electrical circuit is formed between the wire 2 and the substrate 3, and then a working signal is sent to the laser. The laser head 1 emits laser, and at this time, the laser power of the laser head 1 is the third laser power to heat the corresponding position of the substrate 3. And after a period of time, the laser power of the laser head 1 is increased to continuously heat the substrate 3 with the first laser power.
[0043] In this embodiment, when the wire 2 contacts the substrate 3, the conduction signal between the wire 2 and the substrate 3 is received, and a signal is sent to the laser to start emitting laser. At this time, the laser head 1 preheats the substrate 3 with the third laser power. The third laser power is 1800 W, and the duration is 50 ms to form a molten pool on the substrate 3. Since the third laser power is relatively low, in order to prevent the material impurities on the surface and inside of the substrate 3 from quickly vaporizing and splashing due to the excessive temperature generated by the instantaneously too high power, the wire feeding mechanism feeds the wire continuously at the third wire feeding rate, such as at a speed of 475 mm / min for 50 ms. At this time, a stable molten pool has been formed on the substrate 3 and the wire 2 has entered the molten pool. Since the addition of the wire 2 increases the amount of metal to be melted, the third laser power is increased to the first laser power, specifically 1900 W, and the duration is 110 ms. At the same time, the wire feeding rate of the wire 2 is increased to 1750 mm / min to accelerate the melting of the wire 2 to improve the efficiency. Since the absorption rate of the metal material to the laser increases with the increase of temperature, when the melting of the wire 2 reaches a certain amount, the first laser power is reduced to the second laser power, specifically 1700 W, the duration is 80 ms, and the wire feeding rate is 1250 mm / min.
[0044] Continuing to optimize the above embodiment, after the laser head 1 operates at the second laser power for a preset time, it is adjusted to the fourth laser power, and the wire 2 feeds wire continuously at the fourth wire feeding rate; the fourth laser power is less than the second laser power, and the fourth wire feeding rate is less than the second wire feeding rate. In this embodiment, after continuous heating with the third laser power, the first laser power, and the second laser power, the heat input in the molten pool accumulates continuously. Then, the second laser power of the laser head 1 is reduced to the fourth laser power again. The fourth laser power can be 1100W. At the same time, the wire feeding rate is also reduced from the second wire feeding rate to the fourth wire feeding rate, which can be reduced to 900mm / min, and the laser light output duration in this process is 140ms.
[0045] After the laser head 1 operates at the fourth laser power for the above time, the wire 2 is withdrawn from the molten pool, and the wire 2 is melted and the molten pool is heat-insulated with the fifth laser power. Specifically, during the process of withdrawing the wire 2, the wire feeding direction of the wire feeding mechanism is reversed, the wire withdrawing rate is set to -3000mm / min, and the time is 30ms. At this time, the laser power is 1000W to melt the wire 2 and keep it heat-insulated. After the wire 2 is withdrawn from the additive manufacturing product, the wire withdrawing rate is set to -2000mm / min, and the time is 20ms to ensure that the wire 2 is a certain distance away from the surface of the additive manufacturing product. At this time, the laser power is 1000W, and the laser continues to emit light to heat the surface of the additive manufacturing product, reducing the cooling rate of the molten pool and making the surface morphology of the sample more uniform.
[0046] In the above additive manufacturing method, a laser power-time gradient staged power control strategy is adopted for laser wire feeding additive manufacturing. Initially, a low-power laser (1800W) is used to preheat the substrate 3 to form a molten pool, and then the power is increased (1900W) to melt the wire 2. Subsequently, the power is gradually reduced (1700W - 1100W - 1000W) to slow down the cooling rate. At the same time, combined with the dynamic wire feeding rate (5000→450→1750→900mm / min) and the wire withdrawing rate (-3000→-2000mm / min), a dynamic balance of the molten pool is achieved, ensuring that the formed surface is flat and defect-free. Based on the above additive manufacturing method, when additive manufacturing a stainless steel product with a cylindrical structure with a diameter of 3mm and a height of 4mm, the total time only needs 3s, greatly improving the production efficiency, and the morphology of the additive manufacturing product is uniform and defect-free.
[0047] An embodiment of the present invention further provides a laser wire feeding additive manufacturing device, which includes a laser, a wire feeding mechanism, and a control unit. The laser can serve as an energy unit, which can process a molten pool on a substrate 3 and can continuously keep the molten pool warm; while the wire feeding mechanism is a material conveying unit, which can continuously feed wire into the aforementioned molten pool, and when the material in the molten pool reaches a set value, the wire feeding mechanism can also withdraw the wire 2 from the molten pool; for the control unit, it can control the operation of the laser and the wire feeding mechanism. Specifically, it can adjust the laser power of the laser head 1 of the laser and the wire feeding rate of the wire feeding mechanism according to the light emitting time of the laser. Of course, in one embodiment, the additive manufacturing device further includes the above-mentioned vision camera system 4 for real-time positioning of the position of the wire 2. The additive manufacturing device provided in this embodiment uses the above-mentioned additive manufacturing method to prepare products on the substrate 3, not only with very high production efficiency, but also with very high surface consistency of the prepared products. Especially for cylindrical products, the surface is uniform, smooth and flat, ensuring product quality.
[0048] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.
Claims
1. A laser wire feeding additive manufacturing method, characterized in that, Including the following steps: Place the wire at the central position of the wire feeding nozzle, and adjust the focus of the laser head to be below the surface of the substrate; Control the movement of the end of the wire to the surface of the substrate; The laser head processes a molten pool on the surface of the substrate and continuously feeds wire into the molten pool; And when the material in the molten pool reaches the set value, withdraw the wire to a certain distance above the substrate.
2. The laser wire feeding additive manufacturing method according to claim 1, wherein, Detect the relative distance between the center of the wire and the center of the wire feeding nozzle through the visual camera detection system, and when the detected relative distance is within the set range, it is determined that the wire is at the central position of the wire feeding nozzle.
3. The laser wire feeding additive manufacturing method according to claim 1, characterized in that Place a detection plate on the surface of the substrate, control the laser head to move along the optical axis direction, and when the outer diameter of the annular light spot on the detection plate is the smallest, this is the focal position of the laser; Control the laser head to move downward so that the focus of the laser is below the surface of the substrate.
4. The laser wire feeding additive manufacturing method according to claim 1, wherein, During the light emission process of the laser head, adjust the laser power and wire feeding rate according to the light emission time.
5. The laser wire feeding additive manufacturing method according to claim 4, characterized in that, Process a molten pool on the surface of the substrate with the first laser power, and feed the wire into the molten pool at the first wire feeding rate; And when a certain amount of wire is in the molten pool, emit light to the molten pool with the second laser power, and feed the wire at the second wire feeding rate, and the second laser power is less than the first laser power, and the second wire feeding rate is less than the first wire feeding rate.
6. The laser wire feeding additive manufacturing method according to claim 5, characterized in that, When the end of the wire moves to the surface of the substrate, the laser head first heats the surface of the substrate with the third laser power, and feeds the wire at the third wire feeding rate, and after a continuous period of time, the laser head then processes the molten pool with the first laser power; the third wire feeding rate is less than the second wire feeding rate, the third laser power is less than the first laser power, and is greater than the second laser power.
7. The laser wire feeding additive manufacturing method according to claim 5, characterized in that, And when the laser head works at the second laser power for a preset time, adjust it to the fourth laser power, and feed the wire at the fourth wire feeding rate; the fourth laser power is less than the second laser power, and the fourth wire feeding rate is less than the second wire feeding rate.
8. The laser wire feeding additive manufacturing method according to claim 1, characterized in that, After the end of the wire contacts the surface of the substrate, the wire and the substrate form a circuit conduction to control the laser head to emit light to the substrate.
9. The laser wire feeding additive manufacturing method according to claim 1, wherein When the wire is withdrawn, fuse the wire with the fifth laser power, and keep the molten pool warm with the fifth laser power.
10. A wire-fed laser additive manufacturing device, characterized in that, Including: A laser, which processes a molten pool on the substrate and keeps the molten pool warm; A wire feeding mechanism, which continuously feeds wire into the molten pool and withdraws the wire when the material in the molten pool reaches the set value; A control unit, which adjusts the laser power of the laser and the wire feeding rate of the wire feeding mechanism according to the light emission time.