A kind of method of precinct laser sintering fast manufacture metal dieTechnical field
The present invention relates to fast metal mold producing, especially relate to a kind of precinct laser sintering (Selectivelaser sintering, SLS) method of fast metal mold producing.
Background technology:
Continuous aggravation along with market globalization and competition, the speed of model change is constantly accelerated, the exploitation of new product, development, with short production cycle, in batches little, upgrade fast, become one of main trend of manufacturing industry technical development, multi-varieties and small-batch will become manufacturing important production model.In this case, manufacturing industry is had higher requirement to the quick manufacturing of product prototype and the Rapid Manufacturing Technology of mould, has proposed high efficiency, high accuracy, the three high moulds of high life.And the target of metal die Rapid Manufacturing Technology is directly to make the high accuracy durable metal die that can be used for suitability for industrialized production, it is shortening manufacturing cycle, energy-conservation resource-saving, is bringing into play material property, is improving precision, is having very big potentiality aspect reducing cost, and becomes one of 21 century mold making technology of paying close attention to the most of manufacturing industry.Wherein, because the precinct laser sintering selection is wide, utilizing SLS technology directly to make metal die has become the important means that enterprise develops new product, dominates the market fast, is one of hot fields of present various countries research and development.
The SLS fast metal mold producing mainly contains following three kinds of approach, the one, single metal dust high power laser sinter molding, utilize high power laser light (more than the 1000W) that metal dust is scanned sintering, the moulding that successively superposes, profiled member is promptly finished Mold Making through surperficial post processing (polishing, fine finishining); The 2nd, the mixed metal powder laser sintering and moulding, powder for molding is the mixture of two or more metal dust, a kind of fusing point wherein is lower, play binding agent, because the various metal contracts amounts of different melting points are inconsistent, can compensate its Volume Changes mutually, make the gross shrinkage of product little, and the post processing of must infiltrating; But the metal dust of above-mentioned two kinds of methods will melt under laser action; and because the characteristics of SLS " anxious molten speed is cold " sintering; in the metal powders melt sintering process, there are nodularization and sintering shrinkage phenomenon; consequent thermal stress makes sintered part that warpage easily take place, and may there be some tangible sintering defectives in sintered part, and density is not high yet; and required laser sintering and moulding machine laser power is bigger; easily oxidized in the powder sintered process, need inert gas shielding, apparatus expensive.The 3rd, coating film metal powder or metal and the moulding of mixed with resin selective laser sintering obtain metal bonding entity by the low power laser sintering, through degreasing, high temperature sintering, the post processing of infiltration low-melting-point metal, directly form metal die; But the intensity of this class selective laser sintering spare is not high, density is low, cracking, distortion and infiltration hole defect etc. appear in sintered part metal infiltration post processing easily, still there are many technical difficulties in bad to mutual wetability especially metal penetration difficulty aspect metal die, the mechanical property of its mfg. moulding die is not high, precision is lower, surface quality is relatively poor, is difficult to it is directly used as final mould, generally can only use as exemplar or mould master mold.Aspects such as particularly present Ferrious material die Rapid Manufacturing Technology is immature, dimensional accuracy, surface quality, comprehensive mechanical performance existing problems also have suitable distance from practicability.
Summary of the invention:
The object of the present invention is to provide a kind of method of precinct laser sintering fast manufacture metal die, it can prepare high accuracy, metal die that surface quality is good fast.
The object of the present invention is achieved like this:
(1) the metal dust proportioning of variable grain particle diameter: adopt the metal dust of two or more different-grain diameter, by different mass percent mixing match, to improve the shop powder density of powder bed;
(2) SLS metal forming powder preparation: adopt the method for conventional physics or chemical modification that metal dust is carried out surface treatment,, obtain the metal forming powder with the metal dust after the modification and multicomponent bonding agent and lubricant evenly mixing in proportion;
(3) SLS moulding: according to the requirement of die forming, the three-dimensional CAD of designing mould (computer meter auxiliary design) model, and three-dimensional CAD model carried out slicing treatment, above-mentioned metal forming powder is carried out the precinct laser sintering moulding;
(4) roasting: degrade fully at 300-800 ℃ of organic binder bond for laser sintered and burn to lose, obtain product with the inorganic adhesive bonding;
(5) vacuum pressure infiltration metal: product is fixed in the heater in the pressure vessel, then at the metal material of product placed around infiltration, product and metal material are heated and keep vacuum state, after metal temperature is reached for 300-1000 ℃, stop to vacuumize, continue to be heated to 450-1600 ℃ after, charge into Compressed Gas, regulate osmotic pressure then, just can obtain dense structure and high-precision metal die.
Described metal dust is a kind of of iron, titanium, nickel, copper, aluminium powder or its alloy powder.
The particle diameter of metal dust is less than 250 μ m, and two or more different particle diameter is by 1: 2-1: 5 mass percent mixing match.
Described multicomponent bonding agent is the inorganic adhesive of different melting points and the mixture of organic adhesive.
Described inorganic adhesive is ammonium dihydrogen phosphate (ADP) or aluminum phosphate, and described organic adhesive is epoxy resin, nylon, polystyrene powder or polypropylene powder.
Described lubricant is lithium stearate, graphite or molybdenum bisuphide.
Described metal material is zinc, aluminium, magnesium, copper, iron or its alloy.
Described Compressed Gas is compressed air, nitrogen or argon gas.
Also can add following filler at SLS in the metal forming powder preparation: dispersant and light absorber, described dispersant are talcum powder or white carbon, and described light absorber is a carbon black.
Technological parameter decisions such as laser sintering (SLS) is mainly thick by laser power, sweep speed, shop bisque, sweep span, preheat temperature.Adopt the SLS preparation, the advantage that have fast, dimensional accuracy is high, performance good, technology is simple, production cost is low.
The characteristics of vacuum pressure infiltration be molten metal vacuum, etc. seepage flow under the gentle pressure condition, under the certain pressure condition, solidify, it has good seepage flow and curing condition, can avoid the problem that entrains into of gas and field trash, dense internal organization; Molten metal is seepage flow under vacuum pressure, has improved the mold-filling capacity of melt greatly, and time of penetration is short, and eliminated the illeffects in the casting process of gas, can obtain complex shape, any surface finish and accurate in size metallic article.The metalwork density height of this method preparation can be guaranteed on performance and stability effectively.
The specific embodiment:
Below in conjunction with embodiment the present invention is done further to describe in detail.
Embodiment 1:
Present embodiment is that precinct laser sintering is made smart cast copper mould fast.
(1) the metal dust proportioning of variable grain particle diameter: the metal Cu powder of two kinds of average-size 13 μ m and 65 μ m, by 1: 2 mass percent mixing match;
(2) SLS prepares with the metallic copper powder for molding: adopt silane coupler KH-570 that copper powder is carried out surface modification treatment, copper powder after the modification and 6% ammonium di-hydrogen phosphate powder, 8% epoxy resin powder, 3% lithium stearate powder are evenly mixed, obtain the metallic copper powder for molding;
(3) SLS moulding: according to the requirement of die forming, the three-dimensional CAD model of designing mould, and three-dimensional CAD model carried out slicing treatment, in the laser sintering process parameter be: laser power 40W, sweep speed 1500mm/s, sweep span 0.1mm, the thick 0.15mm of shop bisque, 100 ℃ of preheat temperatures are carried out the precinct laser sintering moulding to above-mentioned metallic copper powder for molding;
(4) roasting: laser sintered slowly is heated to 500 ℃, and epoxy adhesive is degraded fully to burn and lost, and continues to be warming up to 700 ℃ of roastings;
(5) vacuum pressure infiltration metal: the product after the roasting is fixed in the heater in the pressure vessel, then at the aluminium alloy of product placed around infiltration, product and aluminium alloy are heated and keep vacuum state, vacuum is less than 1KPa, after the parent metal temperature is reached for 580 ℃, stop to vacuumize, after continuing to be heated to 750 ℃, charge into compressed air, air pressure is 400Kpa, pressurize 10min, and take out the cold back of stove, through thin grinding process, just can obtain dense structure and high-precision smart cast copper mould.
Embodiment 2:
Present embodiment is that precinct laser sintering is made the injection moulding punching block fast.
(1) the metal dust proportioning of variable grain particle diameter: the metallic reducing iron powder of two kinds of average-size 20 μ m and 80 μ m, by 1: 3 mass percent mixing match;
(2) SLS prepares with metallic reducing iron powder for molding: adopt silane coupler KH-570 that the metallic reducing iron powder is carried out surface modification treatment, metal iron powder after the modification and 6% ammonium di-hydrogen phosphate powder, 5% epoxy resin powder, 3% nylon, 6 powder, 3% lithium stearate powder, 1% carbon powder are evenly mixed, obtain the metallic iron powder for molding;
(3) SLS moulding: according to the requirement of die forming, the three-dimensional CAD model of designing mould, and three-dimensional CAD model carried out slicing treatment, in the laser sintering process parameter be: laser power 42.5W, sweep speed 1500mm/s, sweep span 0.1mm, the thick 0.15mm of shop bisque, 105 ℃ of preheat temperatures are carried out the precinct laser sintering moulding to above-mentioned metallic iron powder for molding;
(4) roasting: laser sintered slowly is heated to 550 ℃, and epoxy adhesive and nylon 6 binding agents are degraded fully to burn and lost; Continue to be warming up to 700 ℃ of roastings;
(5) vacuum pressure infiltration metal: the product after the roasting is fixed in the heater in the pressure vessel, then at the copper alloy of product placed around infiltration, product and copper alloy are heated and keep vacuum state, vacuum is less than 500Pa, after the metallic copper alloy temperature is reached for 780 ℃, stop to vacuumize, after continuing to be heated to 1050 ℃, charge into Compressed Gas, air pressure is 300Kpa, pressurize 5min, and take out the cold back of stove, handle through polishing, just can obtain dense structure and high-precision injection moulding punching block.
Embodiment 3:
Present embodiment is that precinct laser sintering is made smart Cast Aluminum Dies fast.
(1) the metal dust proportioning of variable grain particle diameter: the metallic aluminium powder of two kinds of average-size 10 μ m and 50 μ m, by 1: 4 mass percent mixing match;
(2) SLS prepares with the metallic aluminium powder for molding: adopt silane coupler KH-570 that metallic aluminium powder is carried out surface modification treatment, aluminium powder after the modification and 5% ammonium di-hydrogen phosphate powder, 8% epoxy resin powder, 3% lithium stearate powder, 1% carbon powder are evenly mixed, obtain the metallic aluminium powder for molding;
(3) SLS moulding: according to the requirement of die forming, the three-dimensional CAD model of designing mould, and three-dimensional CAD model carried out slicing treatment, in the laser sintering process parameter be: laser power 38W, sweep speed 1600mm/s, sweep span 0.1mm, the thick 0.15mm of shop bisque, 95 ℃ of preheat temperatures are carried out the precinct laser sintering moulding to above-mentioned metal forming powder;
(4) roasting: laser sintered slowly is heated to 550 ℃ of roastings, and epoxy adhesive is degraded fully to burn and lost;
(5) vacuum pressure infiltration metal: the product after the roasting is fixed in the heater in the pressure vessel, then at the low-melting point zinc alloy of product placed around infiltration, product and kirsite are heated and keep vacuum state, vacuum is less than 100Pa, after the parent metal temperature is reached for 320 ℃, stop to vacuumize, after continuing to be heated to 450 ℃, charge into Compressed Gas, regulate osmotic pressure then, air pressure is 300Kpa, pressurize 5min, take out the cold back of stove, handles through polishing, just can obtain dense structure and high-precision smart Cast Aluminum Dies.