CN115157665B

CN115157665B - Continuous 3D printing method and device based on air knife

Info

Publication number: CN115157665B
Application number: CN202211092498.XA
Authority: CN
Inventors: 伍言龙; 陈旭; 刘亚雄; 杨蒙蒙; 王法衡; 石振明; 马广才; 乔健
Original assignee: Individual
Current assignee: Individual
Priority date: 2022-09-08
Filing date: 2022-09-08
Publication date: 2022-12-06
Anticipated expiration: 2042-09-08
Also published as: CN115157665A

Abstract

The invention discloses a continuous 3D printing method and a device based on an air knife, relating to the field of 3D printing, wherein the device comprises: a trough; the forming platform penetrates through the bottom of the material groove and is movably connected with the bottom of the material groove; the vertical feeding motion system is connected with the forming platform and drives the forming platform to move in the trough in the vertical direction; the feed inlet is connected with the interior of the material groove; the light source control system is arranged at the top of the trough, and the light source irradiation direction of the light source control system faces to the forming platform; and the direction of air flow emitted by the air knife control system is flush with the plane of the top of the trough. The invention realizes the continuous strickling of the forming material by the high-speed airflow ejected by the air knife control system, realizes the continuous printing of the high-viscosity forming material and obviously improves the printing efficiency.

Description

Continuous 3D printing method and device based on air knife

Technical Field

The invention relates to the field of 3D printing, in particular to a continuous 3D printing method and device based on an air knife.

Background

Digital Light Processing (DLP) 3D printing technology is a mask-based photocuring technology, and the principle is to convert a printed model into a layer of mask images through a high-resolution optical conversion device, so as to promote Selective layer-by-layer curing of photopolymerizable liquid, thereby realizing the formation of complex parts, and realizing the manufacture of micron-sized structures, and the DLP is significantly superior to additive manufacturing technologies such as Direct writing (DIW), binder Jetting (BJ), selective Laser Sintering (SLS) and the like in terms of dimensional accuracy and macrostructure control, so that DLP is considered as a material manufacturing technology with great development prospects, and is widely applied to the formation of material complex parts such as resin, ceramics, hydrogel and the like in recent years.

However, the technology is based on layer-by-layer accumulation forming, the forming efficiency is low, the formed part is obvious in layering, the surface quality is poor, the mechanical property anisotropy of the formed part is obvious, and the technology is especially applied to the forming process of the ceramic part, the viscosity of ceramic slurry cannot be too high, and the promotion of the solid phase content of the ceramic is limited. The manufactured ceramic parts have the defects of large shrinkage rate, poor surface quality, low forming efficiency, anisotropy and insufficient mechanical property, and are greatly limited in industrial application.

The viscosity of the ceramic paste is high, significantly greater than materials such as resin and hydrogel, while continuous 3D printing requires that the forming material can be quickly replenished to the part forming area in a short time, which is difficult to achieve by virtue of the fluidity of the ceramic paste itself alone. Due to the above problems, the printing efficiency and the surface quality of continuous 3D printing using the photo-curing method are low at present.

Disclosure of Invention

The invention mainly aims to provide a continuous 3D printing method and device based on an air knife, and aims to solve the problems of low continuous printing efficiency and poor surface quality when high-viscosity printing paste is applied to digital light processing 3D printing.

To achieve the above object, the present invention provides an air knife-based continuous 3D printing apparatus, comprising:

a trough;

the forming platform penetrates through the bottom of the material groove and is movably connected with the bottom of the material groove;

the vertical feeding motion system is connected with the forming platform and drives the forming platform to move in the trough in the vertical direction;

the feed inlet is connected with the interior of the material groove;

the light source control system is arranged at the top of the trough, and the light source irradiation direction of the light source control system faces the forming platform;

and the air knife control system is used for controlling the direction of the air flow emitted by the air knife control system to be equal to the plane of the top of the material groove.

Optionally, the material tank includes a main tank and an auxiliary tank, the main tank is located at a side close to the airflow direction, the auxiliary tank is located at a side far from the airflow direction, and a side plate of the auxiliary tank is higher than a side plate of the main tank.

Optionally, the vertical feed motion system comprises a rail-slide mechanism, a ball screw mechanism, or a pulley mechanism.

Optionally, the light source in the light source control system is a laser light source, an ultraviolet light source, an infrared light source, an X-ray light source, or a gamma-ray light source.

Optionally, the forming platform is connected with the bottom of the main groove through a sealing ring.

In addition, to achieve the above object, the present invention also provides a method of continuous 3D printing based on an air knife, the method comprising: lifting the forming platform to be below the upper end surface of the trough through the vertical feeding motion system;

preparing a forming material, and injecting the forming material into the material groove through the feed inlet until the upper liquid level of the forming material is level to the upper interface of the material groove;

opening the air knife control system, and strickling the surface of the forming material to form a smooth and stable forming material surface layer;

and starting the light source control system, printing according to preset printing parameters, continuously supplementing the forming material into the material groove through the feeding hole in the printing process, and continuously scraping under the action of high-speed air flow of the air knife control system until printing is finished to obtain the printed part.

Optionally, the forming material is a photosensitive resin, a hydrogel, a ceramic slurry, a metal slurry or a ceramic-metal mixed slurry.

Optionally, the thickness of the gas flow emitted by the gas knife control system is in the range of 5 μm to 500 μm.

Optionally, the gas flow emitted by the gas knife control system forms a gas flow plane, and the gas flow distribution of the gas flow plane in a direction perpendicular to the gas flow plane is linear distribution, quadratic distribution or exponential distribution.

Optionally, the gas used by the gas knife control system is at least one of nitrogen, argon, and neon.

According to the continuous 3D printing method and device based on the air knife, high-speed airflow motion emitted by an air knife control system is used for replacing repeated reciprocating motion of the scraper, the surface of a forming material within a certain viscosity range is kept flat and stable by using strong impact force of the air knife, the forming material is ensured to be flattened, the flattening time is saved, and the printing efficiency of the high-viscosity forming material applied to photocuring 3D printing is improved.

Drawings

Fig. 1 is a schematic structural view of a continuous 3D printing apparatus based on an air knife according to an embodiment of the present invention;

FIG. 2 is a schematic view of a strike-off process of an air knife control system according to an embodiment of the present invention;

FIG. 3 is a top view of an embodiment of a gas knife control system of the present invention;

fig. 4 is a schematic flow chart of a continuous 3D printing method based on an air knife according to an embodiment of the present invention.

Description of the reference numerals

The implementation, functional features and advantages of the present invention will be further described with reference to the accompanying drawings.

Detailed Description

It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

At present, a continuous liquid interface 3D printing technology based on DLP is used for improving the forming efficiency of printed parts. The basic principle of the technology is that the interface separation force between the forming part and the bottom of the trough is reduced by changing the interface contact state on the basis of the DLP technology, so that the continuous printing process is realized. Although the method can improve the part forming efficiency within a certain limit, the method is mainly suitable for continuous forming of low-viscosity materials such as resin, hydrogel and the like, and for high-viscosity ceramic slurry, the problem that the slurry has high viscosity, is difficult to quickly replenish to a part forming area in a short time and is not beneficial to continuous printing still exists.

An embodiment of the present invention provides a continuous 3D printing apparatus based on an air knife, as shown in fig. 1, the continuous 3D printing apparatus based on the air knife includes:

a trough 1;

the forming platform 8 penetrates through the bottom of the trough 1 and is movably connected with the bottom of the trough 1;

the vertical feed motion system 9, the vertical feed motion system 9 is connected with the forming platform 8, the vertical feed motion system 9 drives the forming platform 8 to move back and forth in the trough 1;

the feed inlet 4 is connected with the interior of the feed trough 1;

the light source control system 5 is arranged at the top of the trough 1, and the light source irradiation direction of the light source control system 5 faces the forming platform 8;

and an air knife control system 6, wherein the direction of air flow emitted by the air knife control system 6 is equal to the plane of the top of the material groove 1.

In fig. 1, the direction of the arrow denoted by p indicates the direction of light irradiation by the light source control system 5, and the direction of the arrow denoted by q indicates the direction of the air flow emitted by the air knife control system 6.

In some embodiments, the trough 1 is divided into a main trough 11 and a secondary trough 12, the main trough 11 being located close to the side of the air flow direction emitted by the air knife control system 6, and the secondary trough 12 being located away from the side of the air flow direction. In the structure shown in fig. 1, the left semi-closed structure with the higher side plate height is a secondary groove 12, the forming platform 8 is movably connected with a main groove 11, and the side plate on one side is shared by the main groove 11 and the secondary groove 12. The main tank 11 may be made of aluminum alloy or stainless steel, the auxiliary tank 12 may be made of aluminum alloy or stainless steel, and the material of the main tank may be different from that of the auxiliary tank.

Fig. 2 is a schematic view of a scene of a leveling process of the air knife control system, as shown in fig. 2, the secondary tank 12 and the air knife control system 6 are respectively located at two sides of the primary tank 11, and the high-speed air flow emitted by the air knife control system 6 sprays the carried-out forming material 2 to a side plate of the secondary tank 12 in the leveling process and remains in the secondary tank 12, so that redundant forming material is conveniently recycled, and waste of the forming material is reduced.

The bottom of the main groove 11 can be connected with the forming platform 8 through the sealing ring 3, the forming platform 8 can lift in the main groove 11, and the sealing ring 3 is convenient for the lifting movement of the forming platform 8 when ensuring that the forming material 2 in the main groove 11 can not leak.

The forming platform 8 comprises a connecting part and a forming part, the connecting part is fixedly or detachably connected with the vertical feeding motion system 9, the connecting part and the forming part are connected or integrally formed, and the vertical feeding motion system 9 drives the connecting part to drive the forming part to move back and forth in a direction close to/far away from the opening above the main groove 11, so that the forming platform is lifted and lowered. The forming platform 8 may be made of aluminum alloy or stainless steel, and the connecting portion and the forming portion may be made of different materials.

The vertical feed motion system 9 can be moved in the vertical direction by a rail-slide mechanism, a ball screw structure, or a pulley structure. The vertical feeding motion system 9 is detachably connected with the forming platform 8, the vertical feeding motion system 9 can drive the forming platform 8 to vertically move, and the forming platform 8 can be detached to be maintained and cleaned when necessary. The motion precision of the vertical feed motion system is higher than 10 mu m, the vertical feed motion system can meet the requirement on the dimensional precision of printed parts, and the forming of complex parts is realized.

The feed inlet 4 can be externally connected with a peristaltic pump and a storage box, the storage box stores the forming material 2, the feed inlet 4 can be arranged at the bottom of the main trough 11, and the forming material 2 can be supplemented to the main trough 11 by controlling the peristaltic pump. After printing is completed, the molding material 2 remaining in the main tank can be discharged from the feed opening 4.

The light source used by the light source control system 5 may be a laser light source, an ultraviolet light source, an infrared light source, an X-ray light source, or a gamma ray light source. The light source irradiates the molding material 2 through the plane of the air flow formed by the air knife control system 6, and the light curing reaction is performed with the molding material 2, so that the molding material is converted into a solid state. When the used forming material 2 is photosensitive resin, an ultraviolet light source can be adopted, and the ultraviolet light can generate higher activation energy, so that a photoinitiator in a system in the photosensitive resin generates free radicals to initiate polymerization crosslinking reaction, and the photosensitive resin is cured.

The top view of the air knife control system 6 is shown in fig. 3, with the direction of the arrows in fig. 3 indicating the direction of air flow movement. The air knife control system is externally connected with an air source, air inlets are formed in two sides in the length direction, compressed air enters the air knife high-pressure cavity 61 through the air inlets, then air flow passes through the narrow and thin air gaps 62, and high-speed air flow sheets with strong impact force and small shearing force are formed in the length direction of the air knife. The direction of the air flow emitted by the air knife control system 6 is equal to the plane of the top of the main groove 11, and after the air knife control system 6 is started, the high-speed air flow sheet emitted from the air slit 62 scrapes the surface of the forming material 2 in the main groove 11 to form a flat and stable surface layer of the forming material.

During the printing process, the light source control system 5 emits light to cure the molding material 2 in the main tank 11, and the cured molding material 2 forms the printed part 7 on the surface of the molding platform 8. The whole printing process is continuously carried out without layering, namely the vertical feeding motion system 9 descends downwards continuously at a certain speed, the printing parts 7 are continuously solidified according to the section of the light source projection, the forming materials 2 are supplemented to the main groove 11 through the feeding port 4, the surface of the forming materials 2 is continuously scraped by high-speed airflow emitted by the air knife control system 6, and the redundant forming materials 2 enter the auxiliary groove 12 until the printing of the printing parts 7 is finished.

An embodiment of the present invention provides a continuous 3D printing method based on an air knife, and referring to fig. 4, fig. 4 is a schematic flowchart of an embodiment of a continuous 3D printing method based on an air knife according to the present invention.

In this embodiment, the method for continuous 3D printing based on an air knife includes:

step S10, the forming platform is lifted to the position below the upper end face of the trough through the vertical feeding motion system;

the light-curing 3D printing mode that the light source is located above the forming platform is adopted, the forming platform is adjusted to a proper printing position, and the forming platform slowly descends in the printing process until printing is completed. The upper end surface of the trough can be regarded as a plane defined by the upper ends of the side plates of the main trough, and when the main trough is filled with the forming material, the upper liquid level of the forming material is superposed with the plane. The distance between the surface of the shaping platform and the upper liquid surface of the shaping material may be 10 μm to 500 μm.

Before the forming platform is controlled to rise, the designed part model can be firstly led into a printing device, the printing model is converted into a layered mask image, and then printing parameters are set according to the characteristics of a forming material. The properties that influence the printing parameters for different forming materials are mainly viscosity, weight and curing rate. The printing parameters may include the rate of descent of the vertical feed motion system, the thickness of the air flow of the air knife control system, and the pattern of air flow distribution. The rate of decrease is related to the rate of solidification of the forming material, and a greater rate of decrease can be set when the forming material solidifies faster. The thickness and pattern of the air flow in the air knife control system affects the leveling of the forming material on the side away from the air knife control system.

S20, preparing a forming material, and injecting the forming material into the material groove through the feed port until the upper liquid level of the forming material is level to the upper interface of the material groove;

the DLP technology is adopted for continuous 3D printing, the used forming material can be photosensitive resin capable of generating photopolymerization, hydrogel, ceramic slurry, metal slurry or ceramic-metal mixed slurry, and the viscosity of the forming material is lower than 10 Pa.s. The embodiment has the advantages of various types of selectable forming materials, small limitation on the viscosity of the forming materials and great improvement on the printing efficiency of high-viscosity ceramic slurry.

Step S30, starting the air knife control system, and strickling the surface of the forming material to form a flat and stable forming material surface layer;

the high-speed airflow ejected by the air knife control system forms an airflow plane, and the airflow plane has strong impact force in the length direction of the air knife, so that the forming material in the trough can be scraped flat to form a flat and stable forming material surface layer. The air knife control system forms stable air flow pressure, balanced flow and adjustable air flow thickness, and the thickness range can be 5-500 μm. The stability of the gas flow on the side away from the gas knife control system is poor when the thickness of the gas flow is small. Regarding the air flow plane as an X-Y plane, the direction perpendicular to the air flow plane is a Z direction, and the air knife control system can control the air flow distribution of the air flow in the Z direction, and the distribution mode can be a linear distribution, a quadratic distribution or an exponential distribution. In different distribution modes, the air flow strength at the side far away from the air knife control system can be set to be stronger, and the flatness and stability of the surface layer of the forming material are ensured.

The air flow rate and the air knife pressure of the air knife control system can be adjusted, and the adjustable range of the air knife pressure is 0.001MPa-5MPa. The gas used by the gas knife control system and connected with an external gas source can be at least one of nitrogen, argon and neon.

Oxygen inhibition means that oxygen in the air has a chemical action on a molding material used for photocuring. The ground state of a general substance is a singlet state, and the stable state of oxygen is a triplet state, and there are two unpaired electrons having the same spin direction, and therefore, it competes with the polymerization reaction of radicals to consume the radicals. Since most of the photo-curing processes are carried out in an air environment, oxygen has a non-negligible effect of inhibiting the radical polymerization reaction of the photo-curing material. In the embodiment, the high-speed air flow formed by the air knife control system can inhibit the forming material from contacting with oxygen in the air, reduce the inhibition of the oxygen on the polymerization reaction, and improve the utilization efficiency and the curing efficiency of the light source.

In addition, the high-speed air flow formed by the air knife control system can also play a cooling role, so that heat generated by continuous curing of the photocuring material in the printing process is taken away in time, heat accumulation in the curing process is reduced, and the continuous forming efficiency is further improved.

And S40, starting the light source control system, printing according to preset printing parameters, continuously supplementing the forming material into the material groove through the feeding hole in the printing process, and continuously scraping under the action of high-speed air flow of the air knife control system until printing is finished to obtain a printed part.

After the light source control system is started, the light source control system can control the irradiation area and the light intensity of the light source, the forming material is solidified according to the section projected by the light source under the action of the light source, the vertical feeding motion system is matched to drive the forming platform to descend at a constant speed, the forming material is supplemented into the material groove through the feeding hole, the forming material is quickly scraped under the action of high-speed airflow and is supplemented to an area where solidification occurs, and then continuous solidification forming is carried out until the printing is completed to obtain the printed part.

After printing is completed, the light source control system and the air knife control system are turned off, and the supply of the forming material into the feed opening is stopped. And taking the printed part off the forming platform, and carrying out post-treatment processes such as cleaning, post-curing and the like.

According to the continuous 3D printing method and device based on the air knife, provided by the embodiment of the invention, the repeated reciprocating movement of the scraper is replaced by the high-speed air flow emitted by the air knife control system, so that the limitation of the traditional top-down ceramic digital light processing 3D printing technology is broken through, the time for scraping the forming material is saved, and the manufacturing efficiency is improved. The high-speed airflow sheet formed by the air knife control system is used as a continuous strickling mechanism, and can also inhibit the forming material from contacting oxygen in the air, reduce the inhibition of the oxygen on polymerization reaction and improve the utilization efficiency and curing efficiency of a light source. The high-speed air flow formed by the air knife control system can also play a cooling role, and can timely take away heat generated by continuous curing of the photo-curing material in the printing process, thereby reducing heat accumulation in the curing process and further improving the efficiency of continuous forming. The high-speed airflow has large power and high strickling efficiency, can realize the continuous and quick strickling of low-viscosity materials such as resin, hydrogel and the like, can also realize the continuous and quick strickling of high-viscosity materials such as ceramics and the like, and breaks through the limitation of the continuous printing efficiency of the high-viscosity materials.

It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or system that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or system. Without further limitation, an element defined by the phrases "comprising a," "8230," "8230," or "comprising" does not exclude the presence of other like elements in a process, method, article, or system comprising the element.

The above-mentioned serial numbers of the embodiments of the present invention are only for description, and do not represent the advantages and disadvantages of the embodiments.

The above description is only a preferred embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes, which are made by using the contents of the present specification and the accompanying drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.

Claims

1. An air-knife-based continuous 3D printing device, comprising:

a trough;

the forming platform penetrates through the bottom of the trough and is movably connected with the bottom of the trough;

the feed inlet is connected with the inside of the feed chute;

the light source control system is arranged at the top of the trough, and the light source irradiation direction of the light source control system faces to the forming platform;

the air knife control system is used for controlling the air flow direction of the air knife to be flush with the plane where the top of the trough is located, the air used by the air knife control system is at least one of nitrogen, argon and neon, the air knife pressure adjusting range of the air knife control system is 0.001MPa-5MPa, the air knife control system is fixed on one side of the trough, the air flow emitted by the air knife control system forms an air flow plane, and the air flow distribution of the air flow plane in the direction perpendicular to the air flow plane is linear distribution, secondary distribution or exponential distribution.

2. The air knife-based continuous 3D printing apparatus of claim 1, wherein the feed slot comprises a main slot and a secondary slot, the main slot being located on a side near the air knife control system, the secondary slot being located on a side away from the air knife control system, a side panel height of the secondary slot being higher than a side panel height of the main slot.

3. The air knife-based continuous 3D printing apparatus of claim 1, wherein the vertical feed motion system comprises a rail-slide mechanism, a ball screw structure, or a pulley structure.

4. The air-knife based continuous 3D printing apparatus of claim 1, wherein the light source in the light source control system is a laser light source, an ultraviolet light source, an infrared light source, an X-ray light source, or a gamma ray light source.

5. The air knife-based continuous 3D printing apparatus of claim 2, wherein the forming platform is connected to the main slot bottom by a sealing ring.

6. An air-knife-based continuous 3D printing method applied to the air-knife-based continuous 3D printing apparatus according to any one of claims 1 to 5, the air-knife-based continuous 3D printing method comprising the steps of:

lifting the forming platform below the upper end surface of the trough through the vertical feeding motion system;

starting the air knife control system to strickle the surface of the forming material to form a flat and stable surface layer of the forming material;

7. The air-knife based continuous 3D printing method according to claim 6, wherein the forming material is a photosensitive resin, a hydrogel, a ceramic paste, a metal paste, or a ceramic-metal hybrid paste.

8. The air knife-based continuous 3D printing method according to claim 6, wherein the thickness of the air knife control system emitting the air flow is in a range of 5 μ ι η to 500 μ ι η.