CN116277377A

CN116277377A - Multi-material bidirectional follow-up powder laying method and device for complex ceramic core

Info

Publication number: CN116277377A
Application number: CN202310110917.6A
Authority: CN
Inventors: 杨浩秦; 单忠德; 黄睿涛
Original assignee: Nanjing University of Aeronautics and Astronautics
Current assignee: Nanjing University of Aeronautics and Astronautics
Priority date: 2023-02-14
Filing date: 2023-02-14
Publication date: 2023-06-23

Abstract

The invention discloses a complex ceramic core multi-material bidirectional follow-up powder spreading method and device, which can realize bidirectional and multi-material powder spreading in a three-position printing process and effectively improve the printing efficiency of a ceramic core; the device comprises three parts of a powder inlet connector, a roller structure and a printing spray head, and forms an X axis of the printing equipment. The powder inlet connector adopts a slope structure and is designed with a plurality of sections of intervals, so that ceramic powder can be conveyed to the joint of the powder inlet connector and the roller under the action of gravity; the roller structure consists of a plurality of sections of small rollers, can realize bidirectional powder spreading according to different directions, and is matched with a powder feeding connector to convey various ceramic powder to different intervals so as to realize directional multi-material powder spreading; the printing nozzle is used as a Y axis during printing, and the adhesive is sprayed according to the model slice to bond ceramic powder. Through the optimization of the invention, the bidirectional multi-material powder spreading integral printing forming can be realized, the printing efficiency of the multi-material three-dimensional printing process is improved by more than one time, and the high-performance forming of the high-temperature alloy single crystal blade is realized.

Description

Multi-material bidirectional follow-up powder laying method and device for complex ceramic core

Technical Field

The invention belongs to the field of 3D printing, and particularly relates to a complex ceramic core multi-material bidirectional follow-up powder laying method and device.

Background

The additive manufacturing technology, namely the 3D printing technology, is a novel rapid prototyping technology which is gradually raised in the 80 s, and the development of the additive manufacturing technology starts to drive the status of the traditional manufacturing industry and shows unique advantages in a plurality of high-tech industries.

3D printing is in many different forms, such as FDM, DLP, EBF, SLA, and materials are also in many different forms, such as thermoplastic plastics, various alloys, photosensitive resins, and so on, but in broad terms, the process of 3D printing is mainly three parts: three-dimensional modeling, namely building a model of a target through a computer; slicing, namely slicing the model through specific software; and (3) model printing, namely stacking the slices layer by layer through a 3D printer to construct a target model. Compared with the traditional manufacturing mode, the production speed of the 3D printer mainly depends on the size of the model rather than the structure, so that the 3D printer has absolute advantages in the production of complex small models, and is in line with the trend of integration and miniaturization of the contemporary electronic industry. The 3D printing does not need a die, and can be produced only by a computer and a printer, so that the space of a factory is greatly saved, and the method is a necessary path in the future of gradual shortage of land resources.

Ceramics are widely used in the fields of chemical industry, machinery, electronics, aerospace, biomedicine and the like due to the characteristics of high mechanical strength and hardness, good chemical stability, excellent acousto-optic electromagnetic heat and the like. Conventional ceramic manufacturing processes typically mix ceramic powders with binders or other additives to form the desired shape by injection molding, die pressing, casting, gelcasting, and the like. The prepared green body is further densified through high-temperature degreasing, sintering and other processes. However, most of these conventional manufacturing processes require a mold to be manufactured in advance, so that the overall production cycle is long, and ceramic parts having highly complex structures cannot be formed. In addition, ceramics are extremely difficult to process due to their extremely high hardness and brittleness. On the one hand, the cutting tool is easy to wear, and on the other hand, defects such as cracking of a sample piece and the like can be generated in the processing process. The problems can be well improved by combining the 3D printing technology.

However, the 3D printing technology of the ceramic core based on the three-dimensional printing technology still has a plurality of problems, the existing three-dimensional printing technology is used for printing the ceramic core large model based on investment casting, the problems of few material types, low forming efficiency, long manufacturing time, weak regulation and control performances on the tissue of the single crystal blade and the like exist, and huge breakthrough and improvement of optimization space are needed for precise forming of the ceramic core and high-performance forming of the high-temperature alloy single crystal blade. The invention aims to solve the problem that the existing three-dimensional printing technology still has how to effectively realize positioning and quantitative powder spreading of various materials by using special materials for strength optimization of partial structures in the high-efficiency multi-material additive manufacturing process.

Disclosure of Invention

The optimizing method and the optimizing device are realized through a novel powder paving structure and a novel printing method, and mainly comprise three parts of a powder inlet connector, a roller structure and a printing spray head, wherein the three parts form an X axis of the printing equipment together, and the printing spray head is attached to the X axis as a Y axis.

The powder inlet connector consists of a powder inlet, a space and a soft cushion. Wherein the inner cavity of the powder inlet connector 1 is divided into a plurality of intervals 101 by interval baffles 102, and a soft cushion 9 is arranged on the contact surface of the bottom and the roller structure 4.

The powder inlet is used for adding printing materials, namely ceramic powder with multiple materials and multiple numbers, and the intervals are used for separating different kinds of printing materials, so that different positions can be paved with different kinds of printing materials, the requirement of printing with multiple materials is met, the condition that the printing materials gather powder to form balls is also reduced, the powder paving quality is improved, and printing failure is avoided. The soft cushion is arranged on the contact surface of the powder inlet connector, which is close to the roller structure, so that the soft cushion and the powder inlet connector can be fully attached, and powder leakage can be avoided in a static state. Meanwhile, in the powder spreading process, the soft cushion can reduce friction caused by rotation of the rolling shaft, and the service life of the structure is prolonged.

The roller structure is composed of a plurality of small roller structures, and the small rollers respectively correspond to a plurality of intervals of the powder inlet connector. The small rollers are controlled by the motor, bidirectional powder spreading is realized through forward and reverse rotation, and meanwhile, as different printing materials can be conveyed at a plurality of intervals, powder spreading of various powders can be realized in the same layer of printing, so that the printing requirement of multiple materials is met. On the other hand, as the diameters of different ceramic powder particles are different, the powder leakage amount of the same angle when the rollers rotate is also different, so that an upper computer is required to control different rollers at different motor speeds, and then the adjustment of parameters such as the powder spreading amount, the powder spreading speed and the like of various materials on the same layer can be realized by matching with the further layer thickness control of the scraper, and the layer thickness precision of the powder spreading layer is improved.

Specifically, when a larger powder spreading amount is needed, the powder leakage amount can be increased in the same time without modifying the movement speed of the X axis by only increasing the rotation speed of the roller, and a larger layer thickness is obtained by matching with the scraper.

The printing nozzle is used for spraying adhesive, and the Y axis as the printing equipment is attached to the X axis of the printing equipment under the control of the upper computer according to the processing of the slicing software on the model. After printing, the X axis moves forward for a distance which is the width of one breadth of the printing spray head, powder is spread and scraped at the same time, then the X axis is static, and the printing spray head moves as the Y axis. While the Y axis moves, the printing nozzle sprays the adhesive to bond the printing powder of the breadth into a specified pattern. The X-axis is again operated forward and the above process is repeated until printing of one layer is completed. After the printing of the layer is finished, the X axis reaches the end point of the positive direction of the X axis of the printing platform, then the X axis moves reversely by a width distance and prints, the process is repeated, and the like, so that the printing of the second layer is finished. Finally, the model is manufactured through layer-by-layer stacking.

After printing, the upper computer controls the powder spreading structure to the upper part of the sand box outside the printing range, cuts off the powder feeding of the powder feeding connector, continuously idles through the roller structure, and discharges the redundant powder inside the structure, so that the cleaning process of the traditional powder spreading structure is avoided, the workload of people is reduced, and the recycling of printing materials is easier to realize.

Drawings

FIG. 1 is a schematic diagram of a multi-material bi-directional follow-up powder laying method and device for a complex ceramic core according to the present invention. The device comprises a powder inlet connector 1, a fixed structure 2, a scraper 3, a roller structure 4, a Y-axis 5, a sand box 6, an X-axis sliding block 7, an X-axis sliding rail 8 and a Z-axis printing platform 11.

FIG. 2 is a detail view of the feed connector;

fig. 3, top view of fig. 2;

among these are "inlet connector 1", "cushion 9", "gap 101", "gap baffle 102".

FIG. 3 is a schematic view showing the X-axis structure of the present invention. The device comprises a powder inlet connector 1, a fixed structure 2, a scraper 3, a roller structure 4 and a forward and backward rotating motor 10.

Fig. 4 is a detailed view of a multi-segment roller, each segment roller corresponding to a spacing of a powder feed connector. Among these are a "forward and reverse motor 10" and a "single-stage roller 402".

Fig. 5 and 2 are plan views.

Detailed Description

The present invention is further illustrated in the following drawings and detailed description, which are to be understood as being merely illustrative of the invention and not limiting the scope of the invention. It should be noted that the words "front", "rear", "left", "right", "upper" and "lower" used in the following description refer to directions in the drawings, and the words "inner" and "outer" refer to directions toward or away from, respectively, the geometric center of a particular component.

As shown in fig. 1, the bidirectional powder spreading printing device in the non-working state is shown, when printing is not started, the roller structure 4 is static and is attached to the cushion 9 of the powder feeding connector 1, the X axis and the Y axis are both in initial positions, and the Z axis printing platform 11 is lifted to the highest point to prepare for printing the first layer slice. Because the powder feeding connector 1 is provided with a plurality of intervals, different ceramic printing material powder can be filled at different intervals, and after printing is started, multi-material single-layer powder spreading in different areas can be realized along with the rotation of the roller structure 4.

Before the printing work starts, different printing material powders are filled from the powder inlet of the powder inlet connector 1, the powders fall into the interval, and slide to the joint of the bottom of the powder inlet connector and the roller structure under the action of gravity by matching with the slope structure, and the powder cannot leak from the interval because the roller structure is attached to the cushion 9. At this time, the preparation work before printing is completed entirely.

When the printing of first layer section begins, X axle slider 7 is driven by the motor and is positively moved on X axle slide rail 8, and roller bearing structure 4 receives positive and negative rotation motor 10's drive simultaneously, and at uniform velocity rotation spills different kinds of printing material powder from roller bearing structure 4's gear clearance, is sent to the print platform surface of relevant position respectively, and cooperation X axle slider 7's motion drives scraper 3 and scrapes shop's powder face, scrapes unnecessary powder, can accurately realize the shop's powder of target layer thickness. After the X axis advances the width of the first printing nozzle, the X axis is static, the printing nozzle is used as the Y axis 5 to spray the adhesive at the appointed position under the control of the upper computer, and the slice pattern of the first width is printed. And then, repeating the process, and printing the first slice pattern, wherein the X axis moves to the positive end point, and the Z axis drives the printing platform to descend by a layer thickness distance after the first slice is printed. When the second slice starts to print, the X axis starts from the maximum travel, namely the forward end point, and moves reversely under the control of the reverse rotation of the forward and reverse rotation motor 10 to perform the second-layer powder paving and printing. When the reverse laying is printed to the forward start point/reverse end point, the forward process is repeated again, and so on. By the mode, the problem that only one layer of powder can be paved for printing in one forward and reverse stroke of the traditional powder paving structure is avoided, and two-way two-time powder paving printing is realized only by using a single structure, so that the efficiency is improved, and meanwhile, the cost is effectively reduced. The single-layer powder spreading quantity can be controlled by controlling the rotating speed of the motor, the unidirectional powder spreading quantity is increased along with the continuous increase of the rotating speed of the motor, and powder spreading with different layer thicknesses can be realized by matching with different printing parameters and the heights of the scrapers.

When printing is finished, firstly cutting off powder feeding of the powder feeding connector, then controlling the X-axis to move forward to the upper part of the sand box, continuously discharging redundant printing material powder through idling of the roller structure, realizing a self-cleaning function, and avoiding the trouble of manual cleaning. The technical means disclosed by the scheme of the invention is not limited to the technical means disclosed by the embodiment, and also comprises the technical scheme formed by any combination of the technical features.

Claims

1. Complex ceramic core multi-material bidirectional follow-up powder paving device, characterized in that: wherein the powder spreading structure is arranged on the X axis of the sand box (6); the powder spreading structure comprises a powder inlet connector (1), a fixing structure (2) and a roller structure (4); two ends of the powder inlet connector (1) are respectively connected and fixed with the scraper (3) through a plurality of fixing structures (2); wherein the roller structure (4) is positioned below the powder inlet connector (1); wherein the inner cavity of the powder inlet connector (1) is divided into a plurality of intervals (101) by interval baffles (102), and a soft cushion (9) is arranged on the contact surface of the bottom and the roller structure (4).

2. The complex ceramic core multi-material bidirectional follow-up powder spreading method and device as set forth in claim 1, wherein: the two sides of the powder inlet connector (1) are symmetrically inclined, and the width of the inner cavity is gradually reduced from top to bottom.

3. The complex ceramic core multi-material bi-directional follow-up powder spreading device according to claim 1, wherein: the roller structure (4) is formed by splicing a plurality of sections of small rollers, the cross section of the roller structure is in a gear shape, the roller structure (4) is connected with a forward and reverse rotation motor (10) to realize forward and reverse rotation, and the powder spreading process is realized through rotation of the rollers; when in work, each interval in the powder inlet connector (1) is opposite to the corresponding small rolling shaft.

4. A complex ceramic core multi-material bidirectional follow-up powder paving method is characterized in that: the method comprises the following steps:

step 1: before printing starts, powder is added through a powder inlet at the top of the powder inlet connector (1), and under the action of gravity, the powder is matched with a slope structure of the powder inlet connector (1), and the printing powder slides to the joint of the roller structure (4).

Step 2: when printing starts, the device is used as an X axis of printing equipment, the X axis is driven by a motor to move forward, and meanwhile, the roller structure (4) starts to rotate under the control of an upper computer;

in the rotating process, printing powder is leaked out and sent to the surface of a printing platform, is paved under the cooperation of a scraper, and moves in a Y axis by a printing head and sprays a binder; after the first layer is printed, reversely moving in the X axis, spreading powder, scraping powder and spraying adhesive at the same time, and printing a second layer; and the third layer is printed in the positive direction of the X axis, and the process is repeated in the similar way, so that the integrated printing of the model is completed.

Step 3: after printing is finished, the device can move to the position above the sand box beyond the printing platform under the drive of the motor, continuously discharges redundant printing powder through continuous idling of the motor of the roller, and achieves a self-cleaning function.