阅读说明：本技术 一种高真空环境防蒸镀金属增材制造装置及其工作方法和制造方法 (Anti-evaporation metal additive manufacturing device in high-vacuum environment and working method and manufacturing method thereof ) 是由 张祺 杨杰 马红林 王国玉 范树迁 于 2019-09-26 设计创作，主要内容包括：本发明涉及一种高真空环境防蒸镀金属增材制造装置及其工作方法和制造方法,其中装置主要包括激光器、高速机械光闸、低速机械光闸以及光开关控制器；所述激光器的激光聚焦头和金属熔融体之间设置有高速机械光闸和低速机械光闸两种闸门；脉冲激光通过高速机械光闸和低速机械光闸作用于金属材料表面将其熔化并在激光入射相反方向产生高速喷射的金属蒸汽和低速飞溅的金属液滴,在高真空环境中蒸汽和液滴先后飞向所述激光器的激光聚焦头方向,在其到达激光聚焦头表面之前两道高速机械光闸和低速机械光闸分别完全闭合从而将其截止在光闸挡板的外侧,以此达到有效保护光学器件的目的,使得金属增材制造有序地进行。(The invention relates to a high-vacuum environment anti-evaporation metal additive manufacturing device and a working method and a manufacturing method thereof, wherein the device mainly comprises a laser, a high-speed mechanical optical shutter, a low-speed mechanical optical shutter and an optical switch controller; two gates of a high-speed mechanical optical gate and a low-speed mechanical optical gate are arranged between a laser focusing head of the laser and the metal melt; the pulse laser acts on the surface of a metal material through a high-speed mechanical optical gate and a low-speed mechanical optical gate to melt the metal material and generate high-speed sprayed metal steam and low-speed splashed metal liquid drops in the direction opposite to the laser incidence direction, the steam and the liquid drops sequentially fly to the laser focusing head direction of the laser in a high vacuum environment, and the two high-speed mechanical optical gates and the low-speed mechanical optical gate are respectively and completely closed before the steam and the liquid drops reach the surface of the laser focusing head so as to be cut off at the outer side of an optical gate baffle, so that the purpose of effectively protecting an optical device is achieved, and metal additive manufacturing is orderly carried out.)

1. A high vacuum environment prevents evaporating metal vibration material disk manufacturing installation, including laser instrument, high-speed mechanical optical gate, low-speed mechanical optical gate and photoswitch controller, characterized by that, the said laser instrument is connected with photoswitch controller, the said high-speed mechanical optical gate and low-speed mechanical optical gate are set up behind laser instrument sequentially; the high-speed mechanical optical shutter consists of more than one mechanical shutter which does uniform-speed rotary motion in opposite directions at equal speed; the low-speed mechanical optical shutter consists of a mechanical shutter which does uniform-speed rotary motion; the optical switch controller can control the laser to emit light and turn off.

2. The apparatus according to claim 1, wherein the relative front and back positions of the high-speed mechanical shutter and the low-speed mechanical shutter on the focusing optical path can be switched.

3. The apparatus according to claim 1, further comprising a mechanical transmission structure, wherein the mechanical transmission structure enables the switching frequency of the high-speed mechanical shutter to be an integral multiple of that of the low-speed mechanical shutter, so as to ensure that the high-speed mechanical shutter and the low-speed mechanical shutter are fully opened at the same time.

4. The apparatus for additive manufacturing of anti-evaporation metal in high vacuum environment according to claim 1, wherein the pulse frequency of the laser is consistent with the low speed shutter switching frequency and/or is divided by an integer multiple thereof.

5. The high-vacuum environment anti-evaporation metal additive manufacturing device according to claim 4, wherein the high-vacuum environment anti-evaporation metal additive manufacturing device can use a photoelectric sensor and a frequency division circuit to realize that the pulse frequency of the laser is divided by an integral multiple of the switching frequency of the low-speed shutter.

6. The high-vacuum environment evaporation-resistant metal additive manufacturing device according to claim 1, wherein the pulsed laser beam emitted by the laser reaches the surface of the metal material after passing through two mechanical shutters of high speed and low speed and melts the metal material, and simultaneously generates metal vapor sprayed at high speed and metal droplets splashed at relatively low speed on the surface of the molten metal.

7. The high-vacuum environment evaporation-proof metal additive manufacturing device according to claim 6, wherein the metal vapor is intercepted by a high-speed mechanical shutter before reaching the surface of the laser focusing head in the opposite direction of the emitted laser beam.

8. The high-vacuum environment anti-evaporation metal additive manufacturing device according to claim 6, wherein the metal liquid drop is intercepted by a low-speed mechanical optical shutter before reaching the surface of the laser focusing head along the opposite direction of the emergent laser beam.

9. The working method of the anti-evaporation metal additive manufacturing device in the high vacuum environment is characterized by comprising the following steps of:

step 1: t is t₀At the moment, two high-speed gates of the high-speed mechanical optical gate and one low-speed optical gate of the low-speed mechanical optical gate are completely opened at the same time;

step 2: the laser is controlled to start emitting light immediately and is closed after the duration dt, and the dt is satisfied

dt<<t₁-t₀；

Wherein, t₁At the moment, the two high-speed gates are completely closed, but the low-speed gate does not produce obvious closing action, and at the moment, a large amount of metal steam is generated on the surface of the molten mass and is sprayed to the direction of the laser focusing head at high speedThe metal vapor is about to reach the outer side surface of the high-speed light gate;

and step 3: t is t₂At the moment, the metal vapor begins to impact and deposit on the outer surfaces of two gates rotating at high speed, and the duration of the process is t₃-t₂And t is₃-t₂≤dt；

And 4, step 4: t is t₄At the moment, the two high-speed gates are fully opened again, the low-speed gate is in a half-open state, and at the moment, t₄And t₅The following relationship is satisfied:

t₄-t₀<<t₅-t₀；

wherein, t₅At the moment, the low-speed gate is completely closed, and the metal liquid drops are about to reach the outer side surface of the low-speed gate;

and 5: t is t₆At the moment, the metal drops begin to impact and deposit on the outer surface of the low-speed gate rotating at a low speed, the duration of the process being about t₇-t₆(ii) a Wherein t is₇At the moment, the metal droplets splashed to the outer side of the low-speed gate are completely intercepted;

step 6: t is t₈And (3) at any moment, the two high-speed gates and the low-speed gate are simultaneously and completely opened again, the whole manufacturing device goes through a complete working period, the laser is prepared to emit light again, and the steps 1-5 are repeated.

10. The working method of the high-vacuum environment anti-evaporation metal additive manufacturing device according to claim 9, wherein the switching frequency of the high-speed gate is an integral multiple of the switching frequency of the low-speed gate, so as to ensure that the high-speed gate and the low-speed gate are completely opened at the same time.

11. The method for operating the anti-evaporation metal additive manufacturing device in the high vacuum environment according to claim 9, wherein the pulse frequency of the laser is consistent with the switching frequency of a low-speed shutter.

12. The application of the working method according to any one of claims 9 to 11 in a space environment or a laboratory high vacuum environment for realizing a sustainable metal laser additive manufacturing task.

13. A manufacturing method of a metal additive manufacturing device for preventing evaporation in a high vacuum environment is characterized in that: the method comprises the following steps:

step (1): the maximum distance L from the laser focusing head to the metal melt is selected according to the requirements of the limit capacity of the light beam focusing device and the size of the focused light spot_0maxAnd the minimum light-emitting aperture d of the laser focusing head_0minMinimum clear aperture d of high-speed optical shutter_1minAnd the minimum aperture d of the low-speed optical gate_2minIs equal in size and is selected according to the following formula:

d_1min＝d_2min＝d_0minL₁/L_0max；

wherein L is₁Is the distance from the shutter closest to the melt;

and (3): estimating the minimum single pulse laser energy dP required to be input during continuous forming according to the physical and chemical properties and the processing technology of the material and the size of a focused light spot_minAnd its corresponding maximum repetition frequency phi/n₁n₂And the pulsed laser metal additive experiment is carried out on the basis to confirm dP_minAnd phi/n₁n₂Rationalizing the calculated value, selecting the minimum pulse laser width dt_min；

And (4): according to the maximum duration t of metal vapor injection₃-t₂The basic principle that the pulse laser width dt is not exceeded is adopted, and the number N of light passing openings of the high-speed optical gate is selected_1min2, and satisfies the following constraint relationship:

D_1max≥d_1min×(1+csc(π/(2N₁)))；

all the light through ports are arranged on the outermost side of the turntable in a centrosymmetric manner;

and (5): selecting the highest rotation speed phi of high-speed optical shutter_maxStarting a pulse laser metal additive experiment, and observing and verifying the inhibition condition of metal vapor;

when it is satisfied with

d_1min/(D_1maxΦ_max)≤t₂-t₀When the temperature of the water is higher than the set temperature,

the metal vapor can be obviously inhibited;

when the inhibition effect is not obvious, gradually reducing the rotating speed of the high-speed optical gate and continuously observing to eliminate the initial rotating speed phi selected by the method_maxMisjudgment caused by overhigh height;

finally selecting the lowest rotation speed phi capable of generating obvious metal steam inhibition effect_minOperating speed as a high speed shutter;

and (6): according to the maximum duration t of the splashed metal droplets₇-t₆The basic characteristics which are not easy to predict are selected, and the quantity N of light-passing ports of the low-speed optical gate is selected₂2, and the two light through ports are arranged on the outermost side of the turntable in a centrosymmetric manner;

and (7): obtaining the arrival delay time t of the liquid drop through experimental observation₆-t₀The maximum rotation speed phi/n of the low-speed shutter is determined from the following relationship_1min：

Φ/n_1min＝d_2min/(D_2maxΦ_min/n₁)≤t₆-t₀；

And (8): the highest repetition frequency phi/n of the pulse laser obtained according to the step (3)₁n₂And the highest rotating speed phi/n of the low-speed optical gate obtained in the step (7)_1minComprehensive judgment parameter n₂Is reasonable.

Technical Field

The invention relates to the technical field of extreme manufacturing, in particular to a high-vacuum environment anti-evaporation metal additive manufacturing device and a working method and a manufacturing method thereof.

Background

Additive Manufacturing (AM) is commonly known as 3D printing, combines computer-aided design, material processing and molding technologies, and is a Manufacturing technology for Manufacturing solid articles by stacking special metal materials, non-metal materials and medical biomaterials layer by layer in modes of extrusion, sintering, melting, photocuring, spraying and the like through a software and numerical control system on the basis of a digital model file. Compared with the traditional processing mode of removing, cutting and assembling raw materials, the method is a manufacturing method through material accumulation from bottom to top, and is from top to bottom. This enables the manufacture of complex structural components that were previously constrained by conventional manufacturing methods and were not possible. The method of using laser beam, electron beam, plasma or ion beam as heat source to heat material for combination and direct manufacture of parts is called high energy beam fast manufacture, which is an important branch of additive manufacturing field and is the most common in industrial field.

In order to realize the logistics support mode of the space station for manufacturing and using and meet the major strategic requirements of on-orbit part manufacturing, research on the aspect of space additive manufacturing technology is being developed internationally, the research provides a key scientific basis and a key technical basis for realizing the logistics support of the space station for manufacturing and using and provides support for meeting the major strategic requirements of the state in the fields of aerospace, national defense and military industry and the like. At present, the main technical routes adopted in the research aspect of the space additive manufacturing technology at home and abroad comprise hot melt deposition, electron beam fuses, selective laser sintering, stereolithography solidification, laser fuses and the like. The materials and the initial morphology of the materials to which the various technical measures are applicable vary widely. The hot melting deposition mode is suitable for low melting point nonmetal wire materials such as PEEK, the selective laser sintering and the stereolithography solidification are suitable for high melting point ceramic powder, and the electron beam fuse wire and the laser fuse wire are suitable for common metal wire materials. The main advantages of laser fuses over electron beam fuses are:

(1) the total power consumption is smaller under the condition of obtaining the same effective heating power;

(2) the laser device with the optical fiber outlet head has smaller volume and better flexibility, and is easy to integrate an experimental system;

(3) the laser core unit has longer service life and is easy to maintain an experimental system;

(4) the light beam scanning is not influenced by an electromagnetic field, and does not generate electromagnetic pollution, so that the environmental adaptability is better.

At present, the main problem of laser fuse metal additive manufacturing in space is that metal vapor and metal liquid drops generated in the manufacturing process easily pollute the end optical device so as to destroy the optical path and cause the failure of the manufacturing system.

Disclosure of Invention

The invention provides an anti-evaporation metal additive manufacturing device suitable for a high-vacuum environment, and a working method and a manufacturing method thereof, which aim to solve the technical problem that a manufacturing system fails because metal steam and metal liquid drops generated in the manufacturing process easily pollute a terminal optical device so as to damage a light path. In order to solve the technical problems, the invention adopts the following technical scheme:

one of the technical schemes of the invention is that the anti-evaporation metal additive manufacturing device in the high vacuum environment comprises a laser, a high-speed mechanical optical shutter, a low-speed mechanical optical shutter and an optical switch controller, wherein the laser is connected with the optical switch controller, and the high-speed mechanical optical shutter and the low-speed mechanical optical shutter are sequentially arranged behind the laser; the high-speed mechanical optical shutter consists of more than one mechanical shutter which does uniform-speed rotary motion in opposite directions at equal speed; the low-speed mechanical optical shutter consists of a mechanical shutter which does uniform-speed rotary motion; the optical switch controller can control the laser to emit light and turn off.

Further, the relative front and back positions of the high-speed mechanical shutter and the low-speed mechanical shutter on the focusing optical path can be switched.

Furthermore, the device also comprises a mechanical transmission structure, and the mechanical transmission structure can enable the switching frequency of the high-speed mechanical optical shutter to be integral multiple of that of the low-speed mechanical optical shutter, so as to ensure that the high-speed mechanical optical shutter and the low-speed mechanical optical shutter are completely opened at the same time.

Further, the pulse frequency of the laser may be identical to and/or divided by an integer multiple of the switching frequency of the low speed shutter.

Preferably, the anti-evaporation metal additive manufacturing device in the high vacuum environment can adopt a photoelectric sensor and a frequency division circuit to realize that the pulse frequency of the laser is the integral multiple frequency division of the switching frequency of the low-speed optical shutter.

Further, the pulsed laser beam emitted from the laser passes through both high-speed and low-speed mechanical shutters, reaches the surface of the metal material and melts it, while generating a high-speed jet of metal vapor and relatively low-speed splashed metal droplets on the surface of the molten metal.

Further, the metal vapor is intercepted by a high-speed mechanical shutter before reaching the surface of the laser focusing head along the opposite direction of the emergent laser beam.

Further, the metal liquid drops are intercepted by a low-speed mechanical shutter before reaching the surface of the laser focusing head along the opposite direction of the emergent laser beam.

The second technical scheme of the invention is to provide a working method of a high-vacuum environment anti-evaporation metal additive manufacturing device, which comprises the following steps:

step 1: t is t₀At the moment, two high-speed gates of the high-speed mechanical optical gate and one low-speed optical gate of the low-speed mechanical optical gate are completely opened at the same time;

step 2: the laser is controlled to start emitting light immediately and is closed after the duration dt, and the dt is satisfied

dt<<t₁-t₀；

Wherein, t₁At the moment, the two high-speed gates are completely closed, but the low-speed gate does not produce obvious closing action, and a large amount of metal steam is melted at the momentGenerating and spraying the molten metal on the surface of the molten body at a high speed towards the direction of the laser focusing head, wherein the metal steam is about to reach the outer side surface of the high-speed optical gate;

it should be noted that dt also means the pulse width of the laser emitted by the laser, and generally means the duration of time during which the laser power is maintained at a certain value.

And step 3: t is t₂At the moment, the metal vapor begins to impact and deposit on the outer surfaces of two gates rotating at high speed, and the duration of the process is t₃-t₂And t is₃-t₂≤dt；

And 4, step 4: t is t₄At the moment, the two high-speed gates are fully opened again, the low-speed gate is in a half-open state, and at the moment, t₄And t₅The following relationship is satisfied:

t₄-t₀<<t₅-t₀；

wherein, t₅At the moment, the low-speed gate is completely closed, and the metal liquid drops are about to reach the outer side surface of the low-speed gate;

and 5: t is t₆At the moment, the metal drops begin to impact and deposit on the outer surface of the low-speed gate rotating at a low speed, the duration of the process being about t₇-t₆(ii) a Wherein t is₇At the moment, the metal droplets splashed to the outer side of the low-speed gate are completely intercepted;

step 6: t is t₈And (3) at any moment, the two high-speed gates and the low-speed gate are simultaneously and completely opened again, the whole manufacturing device goes through a complete working period, the laser is prepared to emit light again, and the steps 1-5 are repeated.

The switching frequency of the high-speed gate is an integral multiple of the switching frequency of the low-speed gate so as to ensure that the high-speed gate and the low-speed gate are completely opened at the same moment.

The pulse frequency of the laser is consistent with the low-speed shutter switching frequency.

The fourth technical scheme of the invention is the application of the working method to the metal laser additive manufacturing task which can continuously work in the space environment or the laboratory high vacuum environment.

The fifth technical scheme of the invention is a manufacturing method of a high-vacuum environment anti-evaporation metal additive manufacturing device, which comprises the following steps:

step (1): the maximum distance L from the laser focusing head to the metal melt is selected according to the requirements of the limit capacity of the light beam focusing device and the size of the focused light spot_0maxAnd the minimum light-emitting aperture d of the laser focusing head_0minMinimum clear aperture d of high-speed optical shutter_1minAnd the minimum aperture d of the low-speed optical gate_2minIs equal in size and is selected according to the following formula:

d_1min＝d_2min＝d_0minL₁/L_0max；

wherein L is₁Is the distance from the shutter closest to the melt, which in practice may be either a high speed shutter or a low speed shutter;

size of focusing light spot is 1.83 lambda f/d_0min；

Where λ is the wavelength of the laser light, f is the focal length of the beam focusing device, and the maximum distance L from the laser focusing head to the molten metal_0maxAbout equal to f;

step (2): according to the material of the parts of the rotary disc light gate and the maximum rotating speed phi of the high-speed light gate_maxCalculating and selecting the maximum diameter D of the high-speed optical gate turntable_1maxTaking the maximum diameter D of the low-speed optical gate turntable_2maxAnd D_1maxEqual;

the maximum rotating speed phi max is determined by the running condition of the selected driving mechanism in the actual working condition, and the maximum rotary table diameter D of the high-speed optical gate is selected according to the material limit strength of the selected rotary table optical gate part after the phi max is determined_1max；

And (3): estimating the minimum single pulse laser energy dP required to be input during continuous forming according to the physical and chemical properties and the processing technology of the material and the size of a focused light spot_minAnd its corresponding maximum repetition frequency phi/n₁n₂And the pulsed laser metal additive experiment is carried out on the basis to confirm dP_minAnd phi/n₁n₂Rationalizing the calculated value and selecting the minimum pulse laserWidth dt_min；

And (4): according to the maximum duration t of metal vapor injection₃-t₂The basic principle that the pulse laser width dt is not exceeded is adopted, and the number N of light passing openings of the high-speed optical gate is selected_1min2, and satisfies the following constraint relationship:

D_1max≥d_1min×(1+csc(π/(2N₁)))；

all the light through ports are arranged on the outermost side of the turntable in a centrosymmetric manner;

and (5): selecting the highest rotation speed phi of high-speed optical shutter_maxStarting a pulse laser metal additive experiment, and observing and verifying the inhibition condition of metal vapor;

when it is satisfied with

d_1min/(D_1maxΦ_max)≤t₂-t₀When the temperature of the water is higher than the set temperature,

the metal vapor can be obviously inhibited;

when the inhibition effect is not obvious, gradually reducing the rotating speed of the high-speed optical gate and continuously observing to eliminate the initial rotating speed phi selected by the method_maxMisjudgment caused by overhigh height;

finally selecting the lowest rotation speed phi capable of generating obvious metal steam inhibition effect_minOperating speed as a high speed shutter;

and (6): according to the maximum duration t of the splashed metal droplets₇-t₆The basic characteristics which are not easy to predict are selected, and the quantity N of light-passing ports of the low-speed optical gate is selected₂2, and the two light through ports are arranged on the outermost side of the turntable in a centrosymmetric manner;

and (7): obtaining the arrival delay time t of the liquid drop through experimental observation₆-t₀The maximum rotation speed phi/n of the low-speed shutter is determined from the following relationship_1min：

Φ/n_1min＝d_2min/(D_2maxΦ_min/n₁)≤t₆-t₀；

And (8): the highest repetition frequency phi/n of the pulse laser obtained according to the step (3)₁n₂And the highest rotation of the low-speed optical gate obtained in the step (7)Speed phi/n_1minComprehensive judgment parameter n₂Is reasonable.

Obtaining n according to₂The reasonable value of (A) is as follows:

n₂＝(Φ/n_1min)/(Φ/n₁n₂)。

in addition, t is mentioned in the manufacturing method of the anti-evaporation metal additive manufacturing device in the high vacuum environment₃、t₂And t₆And the time values are expressed in the same manner as in the above-mentioned working method.

Has the advantages that:

the invention can actively adjust the closing response time of the mechanical optical gate according to the steam jet and liquid drop splashing speed characteristic difference of various metal materials, and effectively control the pollution of the tail end optical device, thereby continuously and stably carrying out the manufacturing process.

Drawings

FIG. 1 is a schematic diagram of a metal additive manufacturing device for preventing evaporation in a high vacuum environment;

FIG. 2a is a diagram of a preferred working method of an anti-evaporation metal additive manufacturing device in a high vacuum environment;

FIG. 2b is a timing diagram of the preferred operation of the anti-evaporation metal additive manufacturing device in a high vacuum environment;

FIG. 3 is a flow chart of a preferred design method of a high vacuum environment anti-evaporation metal additive manufacturing device.

The parts of the drawing are marked as follows:

1. a first high-speed gate; 2. a second high-speed gate; 3. a low-speed gate; 4. a molten metal body; 5. a base plate; 6. a laser focusing head;

in order to more clearly illustrate the detailed description of the invention or the technical solutions in the prior art, the drawings that are needed in the detailed description of the invention or the prior art will be briefly described below. Throughout the drawings, like elements or portions are generally identified by like reference numerals. In the drawings, elements or portions are not necessarily drawn to scale.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that all the directional indicators (such as upper, lower, left, right, front and rear … …) in the embodiment of the present invention are only used to explain the relative position relationship between the components, the movement situation, etc. in a specific posture (as shown in the drawing), and if the specific posture is changed, the directional indicator is changed accordingly.

In addition, the descriptions related to "first", "second", etc. in the present invention are only for descriptive purposes and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.