阅读说明：本技术 金属粉末成型方法 (Metal powder forming method ) 是由 沈香莉 崔道旭 于 2020-11-19 设计创作，主要内容包括：本发明提出了一种金属粉末成型方法,该方法根据工件的结构形成打印壳体模型,针对打印壳体模型进行剖切,从而形成对应的待打印轮廓,通过打印轮廓,将金属粉末包裹在轮廓内部,选择性地进行脱粘处理,然后再进行烧结和热处理,最终得到完整的金属工件,该处理方法能够避免大量粘结剂的使用,从而能够避免烧结过程中的尺寸收缩,特别是对于大型工件而言,该方法还可以大规模节省粘结剂的用量,具有良好的应用前景。(The invention provides a metal powder forming method, which comprises the steps of forming a printing shell model according to the structure of a workpiece, sectioning the printing shell model to form a corresponding contour to be printed, wrapping metal powder inside the contour through the printing contour, selectively performing debonding treatment, and then performing sintering and heat treatment to finally obtain a complete metal workpiece.)

1. A metal powder forming method is characterized by comprising the following steps:

step one, obtaining a three-dimensional structure model of a workpiece to be processed, and extending the three-dimensional structure model into the three-dimensional structure model by taking the surface of the three-dimensional structure model as a base surface to form a printing shell model with the same size as the three-dimensional structure model;

step two, cutting the printing shell model layer by layer, and taking the section of the cut printing shell model as a printing outline so as to form a plurality of printing planes;

step three, paving metal powder in the 3D printing working cylinder, and after a layer of metal powder is paved, printing the surface of the layer of metal powder by a printing structure according to the printing plane obtained in the step two, so that the metal powder at the printing position is bonded;

step four, repeating the step three until the integral printing of the printing shell model is finished, and taking out the printed metal blank;

and fifthly, sintering the metal blank to obtain the metal workpiece after sintering.

2. The metal powder forming method according to claim 1, wherein in step three, the printing structure is a laser printing head, and the laser printing head irradiates the metal powder at the printing position, so that the metal powder is fused and bonded.

3. The metal powder forming method according to claim 1, wherein in the third step, the printing structure is a printing nozzle, and the printing nozzle ejects the adhesive to bond the metal powder at the printing position.

4. The metal powder forming method of claim 3, wherein the fifth step further comprises the steps of performing a debinding treatment on the metal blank body, performing a sintering treatment on the metal blank after the debinding treatment, and obtaining the metal workpiece after the sintering treatment.

5. The metal powder forming process of claim 4, wherein the debinding treatment comprises one or a combination of chemical debinding, thermal debinding, catalytic debinding, supercritical debinding and evaporation.

6. The metal powder forming process of claim 1, wherein the metal powder is one of an iron alloy, an aluminum alloy, and a copper alloy.

7. The metal powder forming method of claim 1, wherein the printing shell mold is closed on the surface and comprises a plurality of closed cavities inside.

8. The metal powder forming method of claim 1, further comprising a sixth step of heat treating the metal workpiece obtained in the fifth step to obtain a metal finished product.

9. The metal powder forming process of claim 8, wherein the heat treatment comprises one or a combination of bulk heat treatment, surface heat treatment, and chemical heat treatment.

10. Use of the metal powder forming process according to any one of claims 1 to 9 in the manufacture of automotive metal parts.

Technical Field

The invention relates to the technical field of additive manufacturing, in particular to a metal powder forming method.

Background

In the traditional manufacturing, the molding processing method of metal powder is injection molding, the metal powder and a binder are mixed and extruded to form a workpiece blank, and then a final metal product is formed through subsequent degreasing, sintering and necessary heat treatment.

On the basis of metal powder injection molding, a material increase manufacturing mode is adopted, ink is jetted to metal powder layer by layer through an ink jet 3D printer, so that a metal blank with a larger volume can be manufactured, a metal workpiece with the larger volume can be formed after the metal blank is subjected to degreasing sintering and heat treatment, however, a large amount of used binder enables the metal blank to generate certain shrinkage deformation in the sintering process, the workpiece with the larger volume is larger, the larger the binder consumption is, the larger the deformation amount generated by the whole workpiece in the sintering process is, and therefore the precision of the large metal workpiece is extremely low due to the metal powder material increase printing mode, and the workpiece can deform in the deformation shrinkage process, so that the quality of the workpiece is influenced.

In addition, the expansion coefficient of the conventionally used iron alloy, aluminum alloy and copper alloy is generally large, and when the iron alloy, aluminum alloy and copper alloy are used together with a binder in the molding production of metal powder, the deformation amount of the final workpiece is extremely large, which is not favorable for the 3D printing processing molding of the metal powder.

Disclosure of Invention

In view of the above, the present invention provides a metal powder molding method capable of greatly reducing the shrinkage rate.

The technical scheme of the invention is realized as follows: the invention provides a metal powder forming method, which comprises the following steps:

step one, obtaining a three-dimensional structure model of a workpiece to be processed, and extending a certain thickness to the inside of the three-dimensional structure model by taking the surface of the three-dimensional structure model as a base surface to form a printing shell model with the same size as the three-dimensional structure model;

step two, cutting the printing shell model layer by layer, and taking the section of the cut printing shell model as a printing outline so as to form a plurality of printing planes;

step three, paving metal powder in the 3D printing working cylinder, and after a layer of metal powder is paved, printing the surface of the layer of metal powder by a printing structure according to the printing plane obtained in the step two, so that the metal powder at the printing position is bonded;

step four, repeating the step three until the integral printing of the printing shell model is finished, and taking out the printed metal blank;

and fifthly, sintering the metal blank to obtain the metal workpiece after sintering.

On the basis of the above technical solution, preferably, in the third step, the printing structure is a laser printing head, and the laser printing head irradiates the metal powder at the printing position, so that the metal powder is fused and bonded.

On the basis of the above technical solution, preferably, in the third step, the printing structure is a printing nozzle, and the printing nozzle sprays the binder so as to bind the metal powder at the printing position.

On the basis of the above technical solution, preferably, the metal powder is one of an iron alloy, an aluminum alloy, a copper alloy, a zinc alloy, a nickel alloy, a cobalt alloy, a chromium alloy, and a titanium alloy.

Further preferably, the metal powder is one of an iron alloy, an aluminum alloy, and a copper alloy.

Further preferably, the iron alloy is gray cast iron or alloy cast iron.

On the basis of the above technical scheme, preferably, the fifth step further includes performing a debonding treatment on the metal blank body, performing a sintering treatment on the debonded metal blank body, and obtaining the metal workpiece after the sintering treatment is completed.

Still further preferably, the debonding treatment includes one or more of chemical debonding, thermal debonding, catalytic debonding, supercritical debonding, and evaporation.

On the basis of the technical scheme, preferably, the surface of the printing shell model is closed, and the interior of the printing shell model comprises a plurality of closed cavities.

In addition to the above technical solution, preferably, in the step one, the thickness extending to the inside of the three-dimensional structure model is 0.5 to 2 mm.

On the basis of the above technical solution, preferably, in the step one, the boundary of the shell generated by the internal extension of the three-dimensional structure model does not exceed the surface of the original workpiece at the position.

On the basis of the technical scheme, preferably, the method further comprises a sixth step of carrying out heat treatment on the metal workpiece obtained in the fifth step to obtain a metal finished product.

On the basis of the above technical solution, preferably, the heat treatment includes one or a combination of bulk heat treatment, surface heat treatment and chemical heat treatment.

The metal powder forming method is mainly used for forming and manufacturing metal parts of automobiles.

Compared with the prior art, the metal powder forming method has the following beneficial effects:

(1) the surface of the model of the three-dimensional workpiece is printed, so that a workpiece blank body with a printing shell on the surface and metal powder filled inside is formed, the printing shell can support the metal powder inside, the metal powder inside is bonded with the printing shell through high-temperature sintering to form a complete workpiece when the metal powder is sintered, and the shrinkage of the metal powder positioned on the inner side of the shell in the sintering process can be reduced as much as possible by adopting the mode of printing the shell, so that the overall production precision of the workpiece is improved;

(2) as one of the preferable schemes, the laser printing shell part is adopted, so that the workload of laser printing can be greatly reduced, the printing speed and the production efficiency are improved, and particularly for large-sized metal workpieces, the printing speed is improved more obviously;

(3) as another preferred scheme, the use of the binder can be greatly reduced by adopting the ink-jet printing shell part, so that the dimensional shrinkage of the metal workpiece caused by the elimination of the binder is greatly reduced in the subsequent de-bonding and sintering processes, the overall shrinkage of the workpiece is mostly determined by the shrinkage of the printing shell part, therefore, the overall shrinkage of the workpiece can be controlled by controlling the thickness of the printing shell, meanwhile, the use of the binder can be greatly reduced by only using the binder for the shell part, the mechanical strength and the production precision of the workpiece can also be improved, and the additive printing of the metal powder can be applied to the large-size metal workpiece.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

Example 1

Obtaining a three-dimensional drawing of a crank connecting rod to be processed, taking the surface of the crank connecting rod as a base surface, carrying out shell extraction treatment on the three-dimensional drawing by using three-dimensional drawing software, wherein the shell extraction thickness is 2mm, obtaining a completely closed crank connecting rod shell structure drawing, carrying out 1000-time equidistant sectioning treatment on the crank connecting rod shell structure to obtain 1000 cross-sectional profile drawings of the crank connecting rod shell, laying gray cast iron powder in a 3D printing working cylinder, printing the gray cast iron powder layer by using a laser printing head when each layer is laid, printing the cross-sectional profile drawings to obtain a cross-sectional profile drawing of the crank connecting rod shell, sequentially printing according to the sequence of 1000 cross-sectional profile drawings in the laying process, finally obtaining a crank connecting rod shell structure blank coated with gray cast iron powder inside, removing redundant gray cast iron powder, putting the structure blank into a sintering furnace for sintering treatment, and obtaining the finished crank connecting rod after sintering.

Example 2

Obtaining a three-dimensional drawing of an engine cylinder cover to be processed, taking the surface of the engine cylinder cover as a base surface, performing shell extraction treatment on the three-dimensional drawing of the engine cylinder cover by using three-dimensional drawing software, wherein the shell extraction thickness is 1mm, obtaining a shell structure drawing of a completely closed engine cylinder cover, performing 10000 times of equal-distance sectioning treatment on a shell of the engine cylinder cover to obtain 10000 sections of shells of the engine cylinder cover, laying aluminum alloy powder in a 3D printing working cylinder, spraying a binder by using a printing nozzle for each layer of laying, bonding and molding the aluminum alloy powder corresponding to the profile drawing, performing 10000 times of laying of the aluminum alloy powder and spraying and printing of the binder to finally obtain an engine cylinder cover structure blank coated with the aluminum alloy powder inside, removing the redundant aluminum alloy powder, immersing the structure blank in an organic solvent, and removing the binder, and (3) drying the structure blank body after the binder is removed, placing the structure blank body into a sintering furnace for sintering when the structure blank body is dried until no organic solvent remains, and performing integral heat treatment and surface heat treatment on the engine cylinder cover after sintering is finished to obtain the finished engine cylinder cover.

Example 3

Obtaining a camshaft stereogram to be processed, taking the surface of the camshaft to be processed as a base surface, performing shell extraction treatment on the camshaft stereogram by using three-dimensional drawing software, wherein the shell extraction thickness is 0.5mm, obtaining a completely closed camshaft shell structure diagram, performing 5000 equal-distance sectioning treatments on the camshaft shell to obtain 5000 camshaft shell section profile diagrams, laying alloy cast iron powder in a 3D printing working cylinder, printing the laminated alloy cast iron powder by using a laser printing head for each layer of laying, wherein the printing patterns are the camshaft shell section profile diagrams, sequentially printing according to the sequence of 5000 section profile diagrams in the laying process to finally obtain a camshaft shell structure blank coated with the alloy cast iron powder inside, removing the redundant alloy cast iron powder, putting the structure blank into a sintering furnace for sintering treatment, and after sintering, respectively carrying out integral heat treatment and surface heat treatment on the corresponding sintered structure, and then carrying out chemical heat treatment to obtain the camshaft.

Comparative example

Obtaining a stereogram of an engine cylinder cover to be processed, carrying out 10000 times of equal distance cutting treatment on the engine cylinder cover to obtain 10000 sections of profile maps of the engine cylinder cover, laying aluminum alloy powder in a 3D printing working cylinder, spraying a binder by using a printing spray head when each layer is laid, bonding and molding the aluminum alloy powder corresponding to the contour diagram, laying the aluminum alloy powder and spraying and printing the binder 10000 times to finally obtain a structure blank body of the engine cylinder cover, removing the redundant aluminum alloy powder, immersing the structure blank body in an organic solvent, removing the binder, drying the structure blank after removing the binder until no organic solvent remains, and (3) putting the structure blank into a sintering furnace for sintering treatment, and after sintering, carrying out integral heat treatment and surface heat treatment on the engine cylinder cover to obtain the finished engine cylinder cover.

The dimensions of the workpieces prepared in examples 1 to 3 and comparative example were measured and compared with the design dimensions, and the shrinkage of the finished workpiece was calculated as follows:

group of	Example 1	Example 2	Example 3	Comparative example
					Shrinkage (%)	0.89	1.02	0.78	12.15

The metal workpiece prepared by the metal powder forming method has obviously low shrinkage rate after processing and forming, and the volume of the workpiece produced by the conventional ink-jet printing mode is obviously reduced after de-bonding and sintering treatment.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.