Background technology
Porous material is a kind of material that is made of metallic framework and hole.Compare with dense material, the typical feature of porous material is that a large amount of holes is contained in inside.Therefore, porous metals have following premium properties, and are little as density, that specific area is big, thermal conductivity is low, heat-sinking capability is high, permeability is strong, energy-absorbing is inhaled the ripple acoustical absorptivity is strong, good biocompatibility etc.In recent years, the porous material part has obtained using very widely, as is used as biomaterial device, damper, buffer, filter, energy absorber, fluid through device, heat exchanger, fire extinguisher, engine exhaust muffler, metal electrode or the like.
That pine is adorned is powder sintered, and (Loose Powder Sintering LPS) is a kind of manufacturing process of common porous part.Its detailed process is the metal dust pine to be loaded on carry out pressureless sintering in the mould, and powder particle bonds mutually in sintering process, thereby forms porous sintered body.This manufacturing process can be produced Fe, Ni, Cu or other alloy porous bodies.Utilizing this technology can produce porosity is 40%~60% porous part.For further improving porosity, can add raising agent.
But when utilizing pine dress powder sintering to be shaped various porous materials and parts, there is following problem:
(1) powder loose sintering method is difficult to the part that direct forming goes out any complicated shape.Need certain complicated shape in the application of porous material, LPS then is restricted then can't direct forming.Need machined in the actual production, this method not only technology is loaded down with trivial details, and production efficiency is low, but also has caused the waste of material.
(2) the powder loose sintering need be used die forming, need part is removed from mould after powder sintered, so Mould design and sintering link is most important, have deviation will influence the dimensional accuracy of part slightly.(list of references: [1] Ceng Zhoushan .316L stainless steel powder STUDY OF VACUUM LOOSE SINTERING. Materials Science and Engineering of Powder Metallurgy .1997,4 (2), 251-254; [2] Zuo Guangwei. determining of Bulk Sintering Temperature of Bronze Powder. powder metallurgy industry .1996,2 (6), 36-37; [3] Ceng Jianbo, Wu Chengping, Qiu Peimin. LOOSE POWDER SINTERING OF POROUS TITANIUM PLATE. the national titanium or titanium alloy seminar .1990 of the 7th of The Nonferrous Metals Society of China December 10)
Summary of the invention
The object of the present invention is to provide a kind of near-net-shape method of porous metal part, this method need not mould, has the advantages that technical process is simple, can make complicated shape.
The near-net-shape method of porous metal part provided by the invention is characterized in that this method comprises the steps:
(1) adopt 3D sculpting software to design the three-dimensional CAD model of part, save as stl file after being treated to by section software then, the data message of stl file is transported to selective laser fusing (Selective Laser Melting, SLM) quickly shaping device;
(2) forming cavity with the SLM quickly shaping device is evacuated, and feeds protective gas then;
(3) the powder feeding mechanism layer thickness that tiles on metal substrate is that 0.05~0.15mm, particle diameter are the metal dust of 10-100 μ m;
(4) adopt laser power to scan, make the outline fusing more than or equal to the laser beam of 100W outline to slice boundaries;
(5) repeating step (3)-(4) finish until the shaping of whole part shell;
(6) with the shell and the powder that is loaded in the shell of formation of parts, integral body places high temperature sintering furnace to carry out thermal sintering.
The present invention combines selective laser fusing (SLM) RP technique with pine dress powder scanning (LPS), this complex method has the following advantages:
(1) shell of use SLM single-channel scanning finished parts, the part of the complicated shape structure that can be shaped.
(2) form porous material by LPS sintering internal loose powder, wayward when having avoided using SLM all to scan inner powder to the hole that forms.
(3) adopt SLM shaping shell, removed the dimensional discrepancy that design and mfg. moulding die bring from.
(4) carry out follow-up loose sintering because any dusty material can be filled in the jacket that SLM is shaped, thereby the related moulding material of this combined shaping method is extensive.
(5) technical process is simple, has avoided traditional machined, saves material.
The specific embodiment
Below in conjunction with accompanying drawing and example detailed process of the present invention is done further detailed elaboration:
(1) in each layer manufacture process, only the metal dust on profile border is evolved and melt, and do not scan inner bulky powder;
(2) repeat said process, after multilayer processing finished, can be shaped to have the metal parts shell of definite shape, certain intensity, and its inner powder has dual mode owing to present loose shape without laser scanning for the internal loose powder-processed:
(a) of the same race powder sintered: the powder of internal loose need not be poured out, direct dusty material as follow-up loose sintering;
(b) xenogenesis is powder sintered: an aperture is reserved in the top of metal parts shell, and the interior metal powder is poured out, and changes to xenogenesis dusty material to be sintered then.
(3) above-mentioned metal shell is inserted in the high temperature sintering furnace together with inner pine dress powder, keep a period of time at a certain temperature, inner pine dress powder then becomes porous material behind sintering, and keeps specific complicated shape under fixed housing.
The shell of metal parts can adopt following steps to be shaped:
(1) adopts 3D sculpting software to design the cad model of part, generate the multilayer slice information and save as stl file by slicing treatment software then, the data of stl file are sent to the SLM quickly shaping device.
(2) the powder feeding mechanism one deck that tiles on workbench is about the powder to be processed (particle diameter is about 10~100 μ m) of 0.1~0.2mm thickness.
(3) adopt laser power more than or equal to YAG laser instrument or the optical fiber laser scan slice profile border of 100W and make the powder smelting of boundary, wherein sweep speed is 20~200mm/s.
(4) repeat above-mentioned steps (2)-(3), up to the shell process finishing of whole part.
Essence of the present invention is that selective laser fusing (SLM) technology is combined with powder loose sintering (LPS) technology.Utilizing the SLM technology can be shaped the advantage of complicated shape for the PLS metal shell that is shaped, promptly is the mould of loose sintering, thereby guarantees that the LPS metal parts that is shaped has the shape of SLM shaping shell.Therefore, use SLM to combine with LPS, can be shaped to have any complicated shape, inside has the part of loose structure.
Example 1
(1) utilizes 3D sculpting software (as UG, Pro/E etc.) to design the CAD 3D model of porous part, save as stl file after handling by section software then, the data message of stl file is input to the SLM quickly shaping device.
(2) be about the 316L powder of stainless steel of 0.1~0.2mm thickness by the powder feeding mechanism one deck that tiles on metal substrate, the particle diameter of powder of stainless steel is about 10~100 μ m, contains the 10wt% methylcellulose in the powder as raising agent.
During as raising agent, its addition generally can be 5-40wt% with methylcellulose.
(3) adopting laser power is YAG laser instrument or the optical fiber laser scan slice profile border of 100W and the powder smelting that makes boundary, and wherein sweep speed is 150mm/s.
(4) repeat above-mentioned steps (2)-(3), up to the shell process finishing of whole part, this moment, metal shell was the needed mould of follow-up loose sintering, and inner 316L powder of stainless steel is the used powder of follow-up loose sintering.
(5) metal shell is comprised inner 316L powder of stainless steel and be sent to vacuum sintering furnace, vacuumize, the setting process route is: be warmed up to 1300 ℃ through 1 hour under the room temperature, be incubated 20 minutes, cool to room temperature is come out of the stove then.
(6) last, the 316L stainless steel parts that being shaped carries out following process, makes the size and dimension of part satisfy the part requirement.
As shown in Figure 1, in the said process, a laser beam scan slice outline makes its fusing, and inside is pine dress powder.Metal shell and inner powder integral body are carried out sintering, then can form porous part with definite shape.
Example 2
(1) utilizes 3D sculpting software (as UG, Pro/E etc.) to design the CAD 3D model of porous part, save as stl file after handling by section software then, the data message of stl file is input to the SLM quickly shaping device.
(2) be about the iron powder of 0.1~0.2mm thickness by the powder feeding mechanism one deck that tiles on metal substrate, powder diameter is about 10~100 μ m, wherein contains boric acid as raising agent, and addition is 2wt%.
During as raising agent, its addition generally can be 1-4wt% with boric acid.
(3) adopting laser power is YAG laser instrument or the optical fiber laser scan slice profile border of 100W and the powder smelting that makes boundary, and wherein sweep speed is 100mm/s.
(4) repeating step (2)-(3), until the iron shell process finishing with definite shape, the iron shell upper is stayed an aperture, and the bulky powder of inside is poured out, and this moment, the iron shell was the needed mould of follow-up loose sintering.
(5) the iron enclosure is injected the Ti6Al4V metal dust, this powder is the used powder of follow-up loose sintering.
(6) the iron shell is comprised inner Ti6Al4V powder and be input to vacuum sintering furnace, vacuumize, the setting process route is: be warmed up to 920 ℃ through 50 minutes under the room temperature, be incubated 30 minutes, cool to room temperature is come out of the stove then.
(7) the iron shell of resultant porous part is removed by machine glazed finish, can be obtained having the Ti6Al4V porous metal parts of certain complicated shape and size.
Example 3
(1) utilizes 3D sculpting software (as UG, Pro/E etc.) to design the CAD 3D model of porous part, save as stl file after handling by section software then, the data message of stl file is input to the SLM quickly shaping device.
(2) be about the iron powder of 0.1~0.2mm thickness by the powder feeding mechanism one deck that on metal substrate, tiles.
(3) adopting laser power is YAG laser instrument or the optical fiber laser scan slice profile border of 100W and the powder smelting that makes boundary, and wherein sweep speed is 140mm/s.
(4) repeating step (2)-(3), until the iron shell process finishing with definite shape, the iron shell upper is stayed an aperture, and the bulky powder of inside is poured out, and this moment, the iron shell was the needed mould of follow-up loose sintering.
(5) the iron enclosure is injected the Ti powder, this powder is the used powder of follow-up loose sintering.
(6) the iron shell is comprised inner Ti powder and be input to vacuum sintering furnace, vacuumize, the setting process route is: be warmed up to 1200 ℃ through 50 minutes under the room temperature, be incubated 1 hour, cool to room temperature is come out of the stove then.
(7) the iron shell of resultant porous part is removed by machine glazed finish, can be obtained having the Ti porous metal parts of certain complicated shape and size.
The above is a preferred embodiments of the present invention, but the present invention should not be confined to the disclosed content of this example and accompanying drawing.So everyly do not break away from the equivalence of finishing under the spirit disclosed in this invention or revise, all fall into the scope of protection of the invention.