Additive manufacturing device based on adjustable annular laser ultrasound

Abstract

The utility model discloses an additive manufacturing device based on adjustable annular laser ultrasound. The additive manufacturing device is provided with a printing forming laser mechanism (1), wherein the printing forming laser mechanism emits printing forming laser to a printing position to form a laser molten pool; the additive manufacturing device is further provided with an ultrasonic oscillation laser mechanism (2), the ultrasonic oscillation laser mechanism emits ultrasonic oscillation laser to the laser molten pool, and the ultrasonic oscillation laser conducts ultrasonic oscillation on the laser molten pool. According to the additive manufacturing device, in the process of printing and forming a target part, the ultrasonic oscillation laser mechanism continuously emits ultrasonic oscillation laser towards the laser molten pool and the peripheral area of the laser molten pool, and the ultrasonic oscillation laser conducts ultrasonic oscillation treatment on the laser molten pool from all directions and multiple angles; and the laser molten pool and the peripheral area of the laser molten pool are subjected to sufficient ultrasonic oscillation, and then the sufficient grain refinement effect and the sufficient hole restraining effect are obtained.

Description

Technical Field

[0001] The utility model relates to a 3D printing forming technology, in particular to an additive manufacturing device based on adjustable ring laser ultrasound. Background Art

[0002] Selective laser melting (SLM) is an existing rapid 3D forming technology. Specifically, a focused laser beam is used to selectively melt metal powder, and three-dimensional objects are formed by layer-by-layer stacking. The SLM technology has the advantages of being fast, flexible, and high in precision, and has broad application prospects in the fields of aerospace, medical devices, mold manufacturing, etc.

[0003] The current problems are as follows:

[0004] 1) For parts formed by printing using the SLM technology, the grain structure inside them is often not satisfactory. For example, columnar grains, coarse grains, as well as defects such as pores and cracks appear during the printing process, etc. As a result, the mechanical properties of the formed parts are not good. In response to such a situation, the current approach is to use other additional grain refinement treatment methods to process the formed parts.

[0005] 2) For parts formed using the SLM technology, there are pores inside them, which will also affect the mechanical properties of the formed parts.

[0006] In addition, some other background technologies (or concepts) related to the present utility model are further described as follows:

[0007] Chinese Patent (Application No.: CN201910446718) discloses a multi-metal part additive manufacturing device and method combining femtosecond and traditional lasers. This device and method are 3D printing forming devices and methods based on the SLM technology. The device includes an additive manufacturing device body, a femtosecond laser output mechanism, a fine powder feeding mechanism, and a fine powder suction mechanism; the additive manufacturing device body includes a printing chamber, a workbench, a lifting device, a metal substrate, a traditional laser output mechanism, and a PLC controller; the workbench is arranged in the printing chamber, the workbench forms a printing groove, and the metal substrate is fixedly arranged in the printing groove through the lifting device in a liftable manner; the PLC controller is connected to the lifting device, the traditional laser output mechanism, the femtosecond laser output mechanism, the fine powder feeding mechanism, and the fine powder suction mechanism. The multi-metal part additive manufacturing device and method combining femtosecond and traditional lasers of the present invention can quickly realize the printing of multi-metal complex parts, can effectively sinter the two-metal junction area with less stress, and avoid cracking at the junction. Summary of the Invention

[0008] The purpose of the present utility model is to provide an additive manufacturing device based on adjustable ring laser ultrasound. The ultrasonic oscillation laser mechanism provided in the additive manufacturing device can perform ultrasonic oscillation treatment on the laser molten pool, thereby achieving the effects of grain refinement and pore suppression.

[0009] In order to achieve the above technical purpose, the present utility model adopts the following technical solutions:

[0010] An additive manufacturing device based on adjustable ring laser ultrasound, the additive manufacturing device having a printing and forming laser mechanism, the printing and forming laser mechanism emitting a printing and forming laser to a printing position to form a laser molten pool;

[0011] The additive manufacturing device is further provided with an ultrasonic oscillation laser mechanism, the ultrasonic oscillation laser mechanism being used to emit an ultrasonic oscillation laser to the laser molten pool and the junction between the laser molten pool and the unmelted area;

[0012] A plurality of ultrasonic signal receivers are arranged around the ultrasonic oscillation laser mechanism, and the plurality of ultrasonic signal receivers are combined together to form an ultrasonic receiving array.

[0013] Furthermore, the additive manufacturing device is provided with a laser ultrasound optimization model, which is used for: collecting the reflected ultrasonic signals received by the ultrasonic signal receivers, establishing an association relationship between the signal characteristics of the collected reflected ultrasonic signals and the printing quality of the formed part, and obtaining the signal characteristic data of the reflected ultrasonic signals corresponding to excellent printing quality through learning, so as to provide a basis for automatically adjusting the parameters of the printing and forming laser emitted by the printing and forming laser mechanism and the parameters of the ultrasonic oscillation laser emitted by the ultrasonic oscillation laser mechanism.

[0014] Furthermore, the ultrasonic oscillation laser emitted by the ultrasonic oscillation laser mechanism is a ring-shaped surrounding ultrasonic oscillation laser, and the ring-shaped surrounding ultrasonic oscillation laser surrounds the laser molten pool, and the surrounding methods include surrounding from the outside of the molten pool and surrounding in a manner where the ring laser partially overlaps with the molten pool.

[0015] The additive manufacturing device of the present utility model has the following beneficial effects compared with the prior art:

[0016] 1) The additive manufacturing device of the present utility model is additionally provided with an ultrasonic oscillation laser mechanism on the basis of the prior art. During the process of printing and forming the target part, the ultrasonic oscillation laser mechanism continuously emits an ultrasonic oscillation laser towards the laser molten pool and its periphery and the junction area between the laser molten pool and the unmelted area, and the emitted ultrasonic oscillation laser is a ring-shaped surrounding ultrasonic oscillation laser, which always surrounds the laser molten pool, and performs ultrasonic oscillation treatment on the laser molten pool from all directions and multiple angles, so that the laser molten pool and its peripheral area obtain sufficient ultrasonic oscillation, and thus sufficient grain refinement effect and pore suppression effect are obtained;

[0017] 2) In the additive manufacturing device of the present utility model, an ultrasonic signal receiving array composed of ultrasonic signal receivers and a laser ultrasonic optimization model are also provided for the ultrasonic oscillation laser mechanism. The laser ultrasonic optimization model collects the reflected ultrasonic signals received by the ultrasonic signal receiving array, and establishes a correlation between the signal characteristics of the collected reflected ultrasonic signals and the printing quality of the formed part. By learning, the signal characteristic data of the reflected ultrasonic signals corresponding to excellent printing quality are obtained, so as to provide a basis for the main control computer to automatically adjust the parameters of the printing and forming laser emitted by the printing and forming laser mechanism and the parameters of the ultrasonic oscillation laser emitted by the ultrasonic oscillation laser mechanism, so as to achieve the optimal printing quality. Brief Description of the Drawings

[0018] Figure 1 It is a schematic diagram of the printing and forming laser mechanism and the ultrasonic oscillation laser mechanism in the additive manufacturing device based on tunable annular laser ultrasound of the present utility model;

[0019] Figure 2 is Figure 1 An enlarged schematic diagram of the laser molten pool in Detailed Embodiment

[0020] The following uses specific embodiments to further illustrate the present utility model:

[0021] This embodiment provides an additive manufacturing device based on tunable annular laser ultrasound. This additive manufacturing device is based on the SLM technology to print and form a target part (the so-called "additive manufacturing" is commonly known as "3D printing", and the SLM technology is a kind of additive manufacturing technology). In fact, the additive manufacturing device of this embodiment is improved on the basis of an existing additive manufacturing device for multi-metal parts combining femtosecond and traditional lasers (application number: CN201910446718).

[0022] See Figure 1 ,

[0023] A printing and forming laser mechanism 1 is provided in the additive manufacturing device (equivalent to the combination of the "femtosecond laser output mechanism" and the "traditional laser output mechanism" in the "additive manufacturing device for multi-metal parts combining femtosecond and traditional lasers"). The printing and forming laser mechanism 1 is an existing combination of laser devices for SLM forming, and this printing and forming laser mechanism 1 is used to emit the laser for SLM forming. The laser emitted by the printing and forming laser mechanism 1 forms a laser molten pool at a specified printing position on the powder bed. Then, under the control of the main control computer, layer-by-layer laser scanning printing is performed based on the three-dimensional drawing of the part to be printed, and the cycle is repeated continuously until the target part is finally printed and formed.

[0024] For the convenience of subsequent description, the laser emitted by the laser mechanism 1 for additive manufacturing is referred to as "additive manufacturing laser".

[0025] In addition, the additive manufacturing device further includes a printing chamber, a workbench, a lifting device, a metal substrate, a conventional laser output mechanism, a PLC controller, a printing cavity, a main control computer, etc. Since these devices and their organizational forms are all prior arts, they will not be described in detail herein. For details, please refer to the Chinese patent application with the application number: CN201910446718.

[0026] The above part is the prior art.

[0027] Different from the prior art, an ultrasonic oscillation laser mechanism 2 (in the art, sometimes also referred to as "laser ultrasonic emission mechanism" or "laser ultrasonic emission module") is further provided in the additive manufacturing device of this embodiment. The setting of the ultrasonic oscillation laser mechanism 2 is an important innovation of this embodiment.

[0028] The ultrasonic oscillation laser mechanism 2 is used to emit ultrasonic laser (also referred to as "ultrasonic laser pulse" in the art) to the laser molten pool and the junction between the laser molten pool and the unmelted area. For the convenience of subsequent description, the laser emitted by the ultrasonic oscillation laser mechanism 2 is referred to as "ultrasonic oscillation laser", which can excite ultrasonic vibration on the irradiated object.

[0029] The ultrasonic oscillation laser can perform ultrasonic oscillation on the laser molten pool and the edge of the laser molten pool (i.e., the junction between the laser molten pool and the unmelted area), or in other words, produce the effect of ultrasonic oscillation on the laser molten pool and the junction between the laser molten pool and the unmelted area.

[0030] In this way, under the action of ultrasonic oscillation, the crystallization of the laser molten pool and the junction between the laser molten pool and the unmelted area will show a "fragmented" situation, and finally the crystal grains will present a grain refinement effect that meets the requirements, thereby greatly improving the mechanical properties of the finally formed part.

[0031] In addition, under the action of ultrasonic oscillation, the tiny bubbles in the laser molten pool are more likely to float out of the laser molten pool. In this way, the pores inside the finally formed part are greatly reduced, that is to say, the pores inside the finally formed part can be effectively eliminated, thereby further improving the mechanical properties of the formed part.

[0032] At the same time, ultrasonic oscillation helps to release the stress in the surrounding area of the laser molten pool during the laser printing process and quickly fill the liquid metal to the grain boundaries. In this way, the generation of printing cracks can be effectively avoided.

[0033] It should be noted that the ultrasonic oscillation laser emitted by the ultrasonic oscillation laser mechanism 2 to the laser molten pool is a circular surrounding laser (as indicated by the arrow A in Figure 2 , hereinafter referred to as "circular surrounding ultrasonic oscillation laser"). During the process of part forming, controlling this circular surrounding ultrasonic oscillation laser to always surround the laser molten pool has the following advantages: Figure 2 As shown at the position indicated by arrow A in Figure 2 , hereinafter referred to as "circular surrounding ultrasonic oscillation laser"), during the process of part forming, controlling this circular surrounding ultrasonic oscillation laser to always surround the laser molten pool has the following advantages:

[0034] 1) Effective ultrasonic oscillation treatment can be carried out on all angles of the laser molten pool;

[0035] 2) The circular surrounding ultrasonic oscillation laser can adjust the circular laser contour size and shape according to the laser molten pool shape, printing speed, etc., so as to achieve a customized laser ultrasonic oscillation effect.

[0036] It should be noted that the way of controlling the circular surrounding ultrasonic oscillation laser to always surround the laser molten pool mentioned above includes surrounding from the outside of the molten pool and surrounding in a way that the circular laser partially overlaps with the molten pool.

[0037] It should be noted that the circular surrounding ultrasonic oscillation laser emitted by the ultrasonic oscillation laser mechanism 2 is essentially a circular light band surrounding the laser molten pool, and its inner diameter, outer diameter, geometric shape of the circular contour, laser pulse frequency and laser power are adjustable. The purpose of adjusting this circular light band is to precisely control the distance or overlap degree between the circular surrounding ultrasonic oscillation laser and the laser molten pool, and the action intensity of the circular surrounding ultrasonic oscillation laser on the oscillation of the laser molten pool.

[0038] For example, by enhancing the width of the circular light band in front of the laser molten pool and increasing the overlap degree between the circular light band and the front area of the laser molten pool, the grain refinement effect in the front part of the laser molten pool can be locally adjusted and the shape of the laser molten pool can be changed.

[0039] During the process of printing and forming parts, the relevant parameters of the circular surrounding ultrasonic oscillation laser (including: circular laser contour size and shape) can be adjusted according to the type of printing material and the parameters of the printing and forming laser emitted by the printing and forming laser mechanism 1. The principle is that different printing materials are suitable for different laser parameters. In this way, the best performance printing effect of different printing materials can be achieved.

[0040] It should be noted that the parameters of the circular surrounding ultrasonic oscillation laser include but are not limited to: inner diameter, outer diameter, contour shape, center distance between the two lasers, overlap degree, circular laser power.

[0041] It should be noted that the ultrasonic oscillation laser mechanism 2 itself is a device of the prior art, and its function of "the parameters of the circular light band, including inner diameter, outer diameter and contour shape, etc. are adjustable" is also an existing function. Therefore, it will not be introduced in detail in this article.

[0042] To facilitate understanding of the implementation effect of the ultrasonic oscillation laser mechanism 2 emitting ultrasonic oscillation laser, a number of ultrasonic signal receivers 21 (devices of the prior art) are also provided around the ultrasonic oscillation laser mechanism 2. These ultrasonic signal receivers 21 are combined to form an ultrasonic receiving array, which is used to receive "the ultrasonic signals that are emitted by the ultrasonic oscillation laser mechanism 2 to the laser molten pool and the junction of the laser molten pool and the unmelted area and then reflected back to the ultrasonic oscillation laser mechanism 2". For the convenience of description, the reflected ultrasonic signals are referred to as "reflected ultrasonic signals".

[0043] It should be noted that the reflected ultrasonic signals can reflect the printing forming quality inside the laser molten pool and in the surrounding area of the laser molten pool, such as whether there are defects such as pores and cracks. The principle is that the defects will act on the propagation process of the ultrasonic waves, and then the ultrasonic signals at the defective positions will be abnormal.

[0044] It should be noted that for each ultrasonic signal receiver 21 in the ultrasonic receiving array, the orientation of receiving signals can be controlled and adjusted (implemented through a PLC controller). In this way, the orientation can be adjusted in real time along with the position of the laser molten pool, so as to achieve the optimal signal receiving effect.

[0045] In addition, for the reflected ultrasonic signals received by the ultrasonic receiving array, a "deep learning algorithm model" is also provided. For the convenience of description, this "deep learning algorithm model" is referred to as the "laser ultrasonic optimization model". This laser ultrasonic optimization model is set in the main control computer of the additive manufacturing device. The function of this laser ultrasonic optimization model is as follows:

[0046] Collect the reflected ultrasonic signals received by the ultrasonic signal receiving array, establish an association relationship between the signal characteristics of the collected reflected ultrasonic signals and the printing quality of the formed part, and obtain the "signal characteristic data of the reflected ultrasonic signals" corresponding to good printing quality through learning, so as to provide a basis for the main control computer to automatically adjust the "parameters of the printing forming laser mechanism 1 emitting printing forming laser" and the "parameters of the ultrasonic oscillation laser mechanism 2 emitting ultrasonic oscillation laser" (such as: power, ultrasonic frequency, inner diameter, outer diameter, frequency, center distance between the annular surrounding ultrasonic oscillation laser and the printing forming laser, etc.).

[0047] It should be noted that most computer software companies can currently implement the laser ultrasonic optimization model according to the above requirements. For those skilled in the art, it can be achieved without creative labor. Therefore, the specific implementation of this laser ultrasonic optimization model will not be introduced in detail in this article.

[0048] In this embodiment, the ultrasonic oscillation laser mechanism 2 can be installed based on a mounting frame. Specifically, the ultrasonic oscillation laser mechanism 2 is installed in the top area of the printing chamber of the selective laser melting forming device, and the installed position does not affect the emission of the printing laser and the normal operation of the powder spreading mechanism.

[0049] It should be noted that the printing and forming laser mechanism 1, the ultrasonic oscillation laser mechanism 2, and the entire additive manufacturing device during operation are all controlled by the main control computer set in the additive manufacturing device.

[0050] The method for printing and forming a target part using the additive manufacturing device of this embodiment is as follows:

[0051] 1. Start the additive manufacturing device and begin printing the target part;

[0052] 2. During the printing and forming process, control the printing and forming laser mechanism 1 and the ultrasonic oscillation laser mechanism 2 to emit low-power lasers but not start beam scanning. Then, through the PLC controller, make the "spot of the printing and forming laser emitted by the printing and forming laser mechanism 1" be located at the center of the "annular surrounding ultrasonic oscillation laser spot emitted by the ultrasonic oscillation laser mechanism 2", or make the spot of the printing and forming laser and the annular surrounding ultrasonic oscillation laser spot have an overlapping part;

[0053] 3. Set the selective laser melting forming parameters of the printing and forming laser, mainly including: laser power, scanning speed, scanning spacing, scanning strategy, layer thickness, etc.;

[0054] Set the parameters of the annular surrounding ultrasonic oscillation laser, mainly including: laser power, laser ultrasonic frequency, inner diameter of the annular laser, outer diameter of the annular laser, geometric shape of the annular contour, distance between the center of the annular laser and the center of the printing laser;

[0055] After the above parameters are set, start printing. At this time, the printing and forming laser starts to quickly scan on the printing plane, and the annular surrounding ultrasonic oscillation laser follows the printing and forming laser for scanning.

[0056] During the printing process, the ultrasonic receiving array set on the ultrasonic oscillation laser mechanism 2 always faces the current printing and forming laser spot and its surrounding adjacent areas under the control of the PLC controller, that is, the laser molten pool and its surrounding areas, to obtain the best ultrasonic signal receiving effect.

[0057] The main control computer analyzes the received ultrasonic signals to judge the printing quality in real time. When it monitors that the printing quality is poor, it adjusts the parameters of the printing and forming laser and the annular surrounding ultrasonic oscillation laser through the PLC controller, so as to achieve the purpose of improving the printing quality.

[0058] Repeat the above steps continuously until all the printed layers are completed to form a complete target part.

[0059] 4. Perform stress relief heat treatment on the metal substrate and the printed part.

[0060] 5. Cut and separate the printed part from the metal substrate.

[0061] For the above method, it can be summarized as follows:

[0062] An additive manufacturing device, which includes:

[0063] S1. Based on the existing additive manufacturing device, an ultrasonic oscillation laser mechanism 2 is set in the additive manufacturing device, and the additive manufacturing device is used to print and form a target part.

[0064] S2. During the process of printing and forming the target part, the printing and forming laser mechanism 1 in the additive manufacturing device emits printing and forming laser to a specified printing position on the powder bed to form a laser molten pool.

[0065] S3. For the laser molten pool, the ultrasonic oscillation laser mechanism 2 continuously emits ultrasonic oscillation laser towards the laser molten pool and the junction of the laser molten pool and the unmelted area until the printing and forming of the target part is completed.

[0066] Under the action of ultrasonic oscillation, the crystal grains are refined, and the tiny bubbles in the laser molten pool float out of the laser molten pool.

[0067] Preferably, the ultrasonic oscillation laser emitted by the ultrasonic oscillation laser mechanism 2 towards the laser molten pool is a circular surrounding ultrasonic oscillation laser.

[0068] During the process of printing and forming the target part, adjust the "parameters of the ultrasonic oscillation laser emitted by the ultrasonic oscillation laser mechanism 2" and the "parameters of the printing and forming laser emitted by the printing and forming laser mechanism 1" according to the signal characteristics of the reflected ultrasonic signal. Such as: power, ultrasonic frequency, inner diameter, outer diameter, frequency, distance between the center of the circular surrounding ultrasonic oscillation laser and the center of the printing and forming laser, etc.

[0069] As described above, the reflected ultrasonic signal is acquired by the ultrasonic receiving array arranged around the ultrasonic oscillation laser mechanism 2.

[0070] The additive manufacturing device of this embodiment has the advantages that

[0071] 1) The additive manufacturing device of this embodiment is additionally provided with an ultrasonic oscillation laser mechanism 2 on the basis of the prior art. During the process of printing and forming the target part, the ultrasonic oscillation laser mechanism 2 continuously emits ultrasonic oscillation laser towards the laser molten pool and the boundary region between the laser molten pool and the unmelted region around it, and the emitted ultrasonic oscillation laser is a circular surrounding ultrasonic oscillation laser. This circular surrounding ultrasonic oscillation laser always surrounds the laser molten pool, and performs ultrasonic oscillation treatment on the laser molten pool from all directions and multiple angles, so that sufficient ultrasonic oscillation is obtained in the laser molten pool and its surrounding area, and thus sufficient grain refinement effect and pore suppression effect are obtained.

[0072] 2) In the additive manufacturing device of this embodiment, an ultrasonic signal receiving array and a laser ultrasonic optimization model are also provided for the ultrasonic oscillation laser mechanism 2. The laser ultrasonic optimization model collects the reflected ultrasonic signals received by the ultrasonic signal receiving array, and establishes a correlation relationship between the signal characteristics of the collected reflected ultrasonic signals and the printing quality of the formed part. By learning, the "signal characteristic data of the reflected ultrasonic signals" corresponding to excellent printing quality is obtained, so as to provide a basis for the main control computer to automatically adjust the "printing and forming laser parameters emitted by the printing and forming laser mechanism 1" and the "ultrasonic oscillation laser parameters emitted by the ultrasonic oscillation laser mechanism 2", in order to achieve the optimal printing quality.

[0073] 3) After combining the all-round and multi-angle ultrasonic oscillation with the ultrasonic signal receiving array and the laser ultrasonic optimization model, it has the beneficial effect of precisely adjusting the stress distribution at all angles in front, behind, left, right and below the molten pool. Through precise stress distribution control, the elimination, reduction, increase, directional distribution, and adjustment of tensile stress and compressive stress states of stress can be realized according to the needs of the part, and differential quantitative stress distribution control can be realized in different regions such as the surface and the interior of the part.

[0074] The above are only the preferred embodiments of the present invention, and are not used to limit the protection scope of the present invention. Therefore, any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An additive manufacturing device based on adjustable ring laser ultrasound, the additive manufacturing device comprising a printing and forming laser mechanism (1), wherein the printing and forming laser mechanism (1) emits a printing and forming laser to a printing position to form a laser molten pool; Features: The additive manufacturing device is further provided with an ultrasonic oscillation laser mechanism (2), the ultrasonic oscillation laser mechanism (2) being installed and arranged based on the installation frame, and the ultrasonic oscillation laser mechanism (2) being used for emitting ultrasonic oscillation laser to the laser molten pool and the junction between the laser molten pool and the unmelted area; A plurality of ultrasonic signal receivers (21) are arranged around the ultrasonic oscillation laser mechanism (2); the plurality of ultrasonic signal receivers (21) are discretely arranged around the ultrasonic oscillation laser mechanism (2); and the plurality of ultrasonic signal receivers (21) are combined together to form an ultrasonic receiving array.

2. The additive manufacturing device based on adjustable ring laser ultrasound according to claim 1, characterized in that: The ultrasonic oscillation laser emitted by the ultrasonic oscillation laser mechanism (2) is a ring-shaped surround ultrasonic oscillation laser, which surrounds the laser molten pool. The surrounding methods include surrounding from the outside of the molten pool and surrounding in a manner in which the ring laser and the molten pool partially overlap.

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