A kind of powder metallurgy planetary gear and preparation method thereof
Technical field
The present invention relates to field of powder metallurgy, be specifically related to a kind of powder metallurgy planetary gear and preparation method thereof.
Background technology
PM technique, with the parts of the shape production requirement high dimensional accuracy extremely close with article shape, complicated shape, can reduce cutting cost significantly.Therefore, sintered metal product as various machinery, device parts and utilize in many-side.
Generally speaking, the alloy powder such as mixing graphite powder and the lubricant powder such as stearic acid, paraffin in iron-based powder and after forming iron-based powder mixed powder, this iron-based powder mixed powder is filled into metal die, press molding and the metallurgy iron-based powder formed body (powder compact) that makes powder.Wherein, iron-based powder can be divided into iron powder (straight iron powder etc.), powdered alloy steel etc. according to composition.Further, iron-based powder also can be divided into atomized iron powder, reduced iron powder etc. according to manufacture method.The density of iron-based powder formed body is generally 6.6-7.1 mg/m3.Further sintering processes implemented for these iron-based powder formed bodies and forms sintered body, and implementing finishing, machining and form sintered metal product as required.When needing to improve hot strength, fatigue strength, after sintering, also implement carburizing heat treatment, brightness heat treatment.But existing powdered metal parts, because in formula, the proportion of various raw material is different, be difficult to guarantee during mixing mix, cause the Density inhomogeneity of the green compact be pressed into, pass through heat treatment, the global density of the part of gained is uneven, causes every mechanical property bad.
Summary of the invention
The invention provides a kind of powder metallurgy planetary gear and preparation method thereof, by the technique of special pulp furnish and science, produce powder metallurgy planetary gear to have wearability good, intensity is high, hardness is high, machinability is good, corrosion-resistant, not easily occur fracture, the feature of long service life.
The technical solution used in the present invention is as follows:
A kind of powder metallurgy planetary gear, it is characterized in that, suppressed by the powder stock of following weight portion and form: iron powder 100, copper powder 1.8-2.0, titanium valve 0.5-0.8, vanadium powder 0.1-0.3, bismuth meal 0.8-1.2, graphite powder 0.5-0.8, modification tree ash 0.1-0.3, rare earth ferrosilicon alloy 0.2-0.6, paraffin 0.1-0.3, ethylene bis stearic acid amide 0.1-0.2, molybdenum bisuphide 0.1-0.3, alundum (Al2O3) 0.2-0.4, boron nitride 0.2-0.4, LiF 0.4-0.5, described rare earth ferrosilicon alloy the trade mark be FeSiRE23, granularity 5-20 mm.
The preparation method of described powder metallurgy planetary gear, is characterized in that, comprises the following steps:
(1) first the base-material iron powder of 40-50% is loaded in high-speed mixer, add the silane resin acceptor kh-550 of base-material iron powder quality 0.3-0.6% wherein, high-speed stirred 5-6 minute, then by copper powder, titanium valve, vanadium powder, bismuth meal, graphite powder, modification tree ash powder, paraffin, ethylene bis stearic acid amide and remaining iron powder add wherein successively, mixed at high speed limit, limit is heated, when temperature is raised to 125-130 DEG C, all the other components in formula are all being added wherein, continue mixing 8-10 minute again, then it is allowed to cool, obtain the iron base powder mixture end of even density,
(2) iron base powder mixture end step (1) obtained loads in mould, makes shape at 550-580Mpa pressure;
(3) compressing green compact are placed in sintering furnace, in the protective atmosphere of hydrogen and nitrogen mixed gas, first it is 1000 ~ 1050 DEG C in temperature, sintering time is 10-20 minute, then increase the temperature to 1150-1180 DEG C with the speed of 10-20 DEG C/min, at this temperature, reburn knot 10-15 minute, then room temperature is down in cooling, is carrying out fine finishining;
(4) carry out Quenching Treatment again after heat treatment fine finishining, hardening heat is 805 ~ 815 DEG C, cool time 2-3 hour; Then at 500-520 DEG C, high tempering process is carried out, insulation 1.5-2 hour; Then lonneal is carried out at 155 ~ 165 DEG C, 2-3 hour;
(5) gas carburizing nitrogen, the 700 DEG C of carbo-nitridings 50 minutes in atmosphere controlled heat treatment furnace of the powder metallurgy planetary gear after lonneal, are cooled to 120 DEG C, insulation 5-8 hour, then cool to room temperature;
(6) powder metallurgy planetary gear after steam treatment carburizing nitrogen nitrogen carries out steam treatment, vapor (steam) temperature 600-700 DEG C, processing time 3-4 hour, then at 200-250 DEG C, is incubated 2-3 hour, finally naturally cools to room temperature.
Described powder metallurgy planetary gear, is characterized in that, in described raw material, the particle diameter of various metal dust is within the scope of 200-400 order.
The preparation method of described powder metallurgy planetary gear, it is characterized in that, described modification tree ash powder is prepared from by the following method: tree ash is first used the salt acid soak 30-40 minute of 25%, then neutralize with alkali lye, use deionized water rinsing impurity elimination again, mix again and with a small amount of ethanol dissolved dilution NDZ-311 titanate coupling agent, the consumption of NDZ-311 titanate coupling agent is the 1-2% of tree ash weight, add in high speed mixer with Sprayable, discharging after stirring 15-20min, oven dry grinds to form 300-400 order powder, obtain modification tree ash powder.
Advantage of the present invention and beneficial effect:
1. powder metallurgy planetary gear of the present invention, carry out the mixing of employing substep, ensure that the even density of finished parts is consistent, improve planetary comprehensive mechanical performance, add man-hour, in the operation of mixed-powder material, first with coupling agent, part iron powder is soaked, and then alloyed powder and lubricant added in wetting iron powder in proportion mix, finally adding wherein through remaining iron powder, abundant mixing, the mixed-powder of gained is repressed, sintering, heat treatment, surface treatment, finally obtain final product, the powder metallurgy processing technology adopted, significantly reduce manufacturing cost, improve stock utilization and productivity ratio.
2. powder metallurgy planetary gear of the present invention, adds the metal dust of different proportion in composition of raw materials, makes the planetary gear prepared reach high strength, the performance of high rigidity and high abrasion; In formula, add appropriate kollag, add the self-lubricating property of product; With the addition of appropriate vanadium powder, modification tree ash powder, improve the intensity of product and anti-wear performance and self-lubricating property.
Detailed description of the invention
Below by embodiment, the present invention is described in further detail, but the present invention is not only confined to following examples.
Embodiment takes following raw materials (kg) iron powder 100, copper powder 1.9, titanium valve 0.6, vanadium powder 0.2, bismuth meal 1.0, graphite powder 0.7, modification tree ash 0.2, rare earth ferrosilicon alloy 0.5, paraffin 0.2, ethylene bis stearic acid amide 0.15, molybdenum bisuphide 0.2, alundum (Al2O3) 0.3, boron nitride 0.3, LiF 0.45, described rare earth ferrosilicon alloy the trade mark be FeSiRE23, granularity 5-20 mm
Preparation method, comprises the following steps:
(1) first the base-material iron powder of 40-50% is loaded in high-speed mixer, add the silane resin acceptor kh-550 of base-material iron powder quality 0.3-0.6% wherein, high-speed stirred 5-6 minute, then by copper powder, titanium valve, vanadium powder, bismuth meal, graphite powder, modification tree ash powder, paraffin, ethylene bis stearic acid amide and remaining iron powder add wherein successively, mixed at high speed limit, limit is heated, when temperature is raised to 125-130 DEG C, all the other components in formula are all being added wherein, continue mixing 8-10 minute again, then it is allowed to cool, obtain the iron base powder mixture end of even density,
(2) iron base powder mixture end step (1) obtained loads in mould, makes shape at 550-580Mpa pressure;
(3) compressing green compact are placed in sintering furnace, in the protective atmosphere of hydrogen and nitrogen mixed gas, first it is 1000 ~ 1050 DEG C in temperature, sintering time is 10-20 minute, then increase the temperature to 1150-1180 DEG C with the speed of 5-8 DEG C/min, at this temperature, reburn knot 10-15 minute, then room temperature is down in cooling, is carrying out fine finishining;
(4) carry out Quenching Treatment again after heat treatment fine finishining, hardening heat is 805 ~ 815 DEG C, cool time 2-3 hour; Then at 500-520 DEG C, high tempering process is carried out, insulation 1.5-2 hour; Then lonneal is carried out at 155 ~ 165 DEG C, 2-3 hour;
(5) gas carburizing nitrogen, the 700 DEG C of carbo-nitridings 50 minutes in atmosphere controlled heat treatment furnace of the powder metallurgy planetary gear after lonneal, are cooled to 120 DEG C, during insulation 5-8, then cool to room temperature;
(6) powder metallurgy planetary gear after steam treatment carburizing nitrogen nitrogen carries out steam treatment, vapor (steam) temperature 600-700 DEG C, processing time 3-4 hour, then at 200-250 DEG C, is incubated 2-3 hour, finally naturally cools to room temperature.
In raw material, the particle diameter of various metal dust is within the scope of 300-400 order.
Modification tree ash powder is prepared from by the following method: tree ash is first used the salt acid soak 30-40 minute of 25%, then neutralize with alkali lye, use deionized water rinsing impurity elimination again, mix again and with a small amount of ethanol dissolved dilution NDZ-311 titanate coupling agent, the consumption of NDZ-311 titanate coupling agent is the 1-2% of tree ash weight, adds in high speed mixer with Sprayable, discharging after stirring 15-20min, oven dry grinds to form 300-350 powder, obtains modification tree ash powder.
The Performance Detection of the powder metallurgical gear that the present embodiment obtains is as follows:
Tensile strength sigma b (MPa): 785
Yield strength σ s (MPa): 568
Percentage elongation δ 5 (%): 17.1
Contraction percentage of area ψ (%): 36.