CN101579738A - Double pressing molding method for preparing high-density powder metallurgical iron-base part - Google Patents
Double pressing molding method for preparing high-density powder metallurgical iron-base part Download PDFInfo
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Abstract
The invention relates to a double pressing molding method for preparing a high-density powder metallurgical iron-base part, belonging to the powder metallurgy technology field. Water atomized iron powder, copper powder, nickel powder, molybdenum powder and graphite are taken as raw materials and mixed on a star heart type mixing mill to obtain an even iron-base powder mixture; then, die wall lubrication technology is adopted to evenly coat zinc stearate on the surfaces of a mould and an upper punch, and then the double pressing method is adopted for preparing the iron-base part; under the condition that total pressing energy is unchangeable, the first pressing energy is 10-30% of the total pressing energy, and the second pressing energy is 70-90% of the total pressing energy. At the temperature of 1120-1250 DEG C, the product is sintered under the nitrogen protection atmosphere for 1-3h, so that the high-density iron-base part can be obtained. The method can be used for preparing the high-density iron-base part and has the advantages of high utilization rate of materials and product accuracy, little environmental pollution, high production efficiency, low cost, etc.
Description
Technical field:
The invention belongs to powder metallurgical technology, a kind of method that adopts twice compacting of high velocity compacted technology to prepare the high-density powder metallurgy iron-base part is provided especially.
Background technology
Powder metallurgy be the preparation of logging material with part forming in one, energy-conservation, material-saving, efficient, near clean (end) be shaped, do not have the advanced manufacturing technology of (lacking) pollution, having irreplaceable status and effect in the material and parts manufacturing industry, is the important means that improves material property and development new material.Powdered metallurgical material is the complex of matrix and hole, and hole is its inherent characteristic, and the existence of hole has reduced effective bearing area, has increased the possibility that stress is concentrated, and it can cause crackle, reduces toughness and fatigue strength.Therefore, the range of application of powdered metal parts be enlarged, the high densification of goods must be realized.For iron-based powder metallurgy parts, density reaches 7.2g/cm
3After, its hardness, tensile strength, fatigue strength, toughness etc. all can be geometric progression with the increase of density and increase.Development high density, high strength and high accuracy sintered metal product are the developing direction and the research emphasis of powder metallurgy industry, improve the product densification degree and will promote the improvement of its performance greatly.
At present, the method for raising sintered metal product density mainly contains temperature and pressure technology (WC), repressing and re-sintering technology (P2S2), power magnetic compact technique (DMC), power forging technology (P/F), blast compact technique (EC), quick omnidirectional's compact technique (ROC) etc.The key of temperature and pressure technology is to use a kind of special lubricant, and the adding of lubricant has reduced sintered density, has weakened the mechanical performance of goods simultaneously, and easily causes environmental pollution; The repressing and re-sintering technology has been carried out big quantity research, but owing to cost is higher its application is restricted; The research of current driving force magnetic compact technique mainly concentrates on the U.S. and Japan, and other countries rarely have report, and relevant device and theoretical utmost point imperfection, thereby has limited it in industrial applying.The research starting that use in powder metallurgy in domestic relevant magnetic field is later relatively, only in magnetic material preparation, magnetic field sintering Primary Study is arranged, and does not appear in the newspapers as yet so far as for moving magnetic pressure system Study on Technology; The power forging technology is owing at high temperature carrying out, so its surface smoothness is relatively poor and die cost is higher.Simultaneously, can rupture when being out of shape, thereby the application of forging parts also is subjected to some restrictions owing to the porous pressed compact that heats; The blast compact technique is because safety inadequately, and poor controllability, production efficiency are low, can pollute etc. environment its application is restricted; Fast omnidirectional's compact technique is because production efficiency is low, cost is high and part dimension is subjected to shortcoming such as press size control and do not obtain industrial applications.
Calendar year 2001 in U.S. metal dust federation, Sweden
The Skoglund Paul of AB company has proposed high velocity compacted technology (High Velocity Compaction, be called for short HVC), it and traditional compact technique have many similitudes on production technology, as filling mould, compacting and the goods demoulding, but this technology tradition compacting has the following advantages: 1. high green density, and Density Distribution is even; 2. low radial elastic aftereffect, low knockout press; 3. excellent combination property; 4. high production rate, the big part that is shaped economically.With regard to preparation high-density powder metallurgy goods, this technology receives much concern owing to having good cost performance.
At present, this Study on Technology is in the starting stage abroad, mainly concentrates on the preparation of adopting single compacting research iron powder, stainless steel powder, iron-base part.
Summary of the invention
The purpose of this invention is to provide a kind of method for preparing the high-density powder metallurgy iron-base part, improve stock utilization and product precision, reduce environmental pollution, reduce production costs.
A kind of twice method for press forming for preparing the high-density powder metallurgy iron-base part adopts high velocity compacted-die wall lubrication technology, it is characterized in that: adopting water-atomized iron powder, copper powder, nickel powder, molybdenum powder and graphite is raw material,
The particle diameter of water-atomized iron powder is that 20～200 μ m, content are 95.2～96wt%, and copper powder content is 1.2～1.5wt%, and nickel powder content is 1.8～2.0wt%, and molybdenum powder content is 0.2～0.5wt%, and content of graphite is 0.5～0.8wt%.At first described water-atomized iron powder, copper powder, nickel powder, molybdenum powder and graphite are carried out mixingly on star core type cylinder machine, obtain uniform iron-based powder mix; Adopt the die wall lubrication technology that zinc stearate evenly is coated in mould and upper punch surface then, then adopt double-press process to prepare iron-base part; Under the certain situation of total compacting energy, suppress energy for the first time and be 10～30% of total compacting energy, suppress energy for the second time and be 70～90% of total compacting energy.Prepared iron-based pressed compact under nitrogen protection atmosphere in 1120～1250 ℃ of sintering 1～3h, thereby obtain highdensity iron-base part.
To select different total compacting energy to carry out energy distribution according to the actual service condition of iron-base part in the technological process.Because always suppress energy, energy distribution all has material impact to the density of iron-base part, the most directly influences the performance and the life-span of iron-base part.
Advantage of the present invention is that can to prepare density be 7.50～7.62g/cm
3Iron-base part, this is that traditional compacting sintering technology is difficult to reach.For iron-based powder metallurgy parts, density reaches 7.2g/cm
3After, its hardness, tensile strength, fatigue strength, toughness etc. all can be geometric progression with the increase of density and increase.This technology is a kind of near-net-shape technology, and stock utilization height, product precision height, environmental pollution is little, production efficiency is high, cost is low.In addition, this technology makes the powder metallurgy iron-based part that preparation is bigger on miniature high-speed impact forging press become possibility.
Description of drawings
Fig. 1 is a process chart of the present invention
Fig. 2 is the iron-base part sintered density of single pressing preparation
Fig. 3 is the iron-base part sintered density of double-press process preparation
The specific embodiment
Embodiment 1: suppress energy for the first time and be 10% of total compacting energy
It is mixing to adopt granularity to be that the water-atomized iron powder of 20～200 μ m and 0.8% graphite powder, 2% nickel powder, 1.5% copper powder, 0.5% molybdenum powder carry out on star core type cylinder machine, obtains uniform iron-based powder mix; Adopt the die wall lubrication technology that lubricant stearic acid zinc evenly is coated in mould and upper punch surface subsequently, when total compacting energy is 1590J, with suppress for the first time energy serve as total compacting energy 10%, to suppress energy for the second time serve as that 90% the energy distribution principle of always suppressing energy is suppressed iron-based powder on the high speed impact shaping press, obtains the pressed compact of required form.In 1120～1250 ℃ of sintering 1～3h, the density of gained iron-base part is 7.6～7.624g/cm to this pressed compact under nitrogen protection atmosphere
3, tensile strength is 700～900MPa.
Embodiment 2: suppress energy for the first time and be 15% of total compacting energy
It is mixing to adopt granularity to be that the water-atomized iron powder of 20～200 μ m and 0.8% graphite powder, 2% nickel powder, 1.5% copper powder, 0.5% molybdenum powder carry out on star core type cylinder machine, obtains uniform iron-based powder mix; Adopt the die wall lubrication technology that lubricant stearic acid zinc evenly is coated in mould and upper punch surface subsequently, when total compacting energy is 1590J, with suppress for the first time energy serve as total compacting energy 15%, to suppress energy for the second time serve as that 85% the energy distribution principle of always suppressing energy is suppressed iron-based powder on the high speed impact shaping press, obtains the pressed compact of required form.In 1120～1250 ℃ of sintering 1～3h, the density of gained iron-base part is 7.58～7.625g/cm to this pressed compact under nitrogen protection atmosphere
3, tensile strength is 700～900MPa.
Embodiment 3: suppress energy for the first time and be 20% of total compacting energy
It is mixing to adopt granularity to be that the water-atomized iron powder of 20～200 μ m and 0.8% graphite powder, 2% nickel powder, 1.5% copper powder, 0.5% molybdenum powder carry out on star core type cylinder machine, obtains uniform iron-based powder mix; Adopt the die wall lubrication technology that lubricant stearic acid zinc evenly is coated in mould and upper punch surface subsequently, when total compacting energy is 1590J, with suppress for the first time energy serve as total compacting energy 20%, to suppress energy for the second time serve as that 80% the energy distribution principle of always suppressing energy is suppressed iron-based powder on the high speed impact shaping press, obtains the pressed compact of required form.In 1120～1250 ℃ of sintering 1～3h, the density of gained iron-base part is 7.59～7.62g/cm to this pressed compact under nitrogen protection atmosphere
3, tensile strength is 700～900MPa.
Embodiment 4: suppress energy for the first time and be 25% of total compacting energy
It is mixing to adopt granularity to be that the water-atomized iron powder of 20～200 μ m and 0.8% graphite powder, 2% nickel powder, 1.5% copper powder, 0.5% molybdenum powder carry out on star core type cylinder machine, obtains uniform iron-based powder mix; Adopt the die wall lubrication technology that lubricant stearic acid zinc evenly is coated in mould and upper punch surface subsequently, when total compacting energy is 1590J, with suppress for the first time energy serve as total compacting energy 25%, to suppress energy for the second time serve as that 75% the energy distribution principle of always suppressing energy is suppressed iron-based powder on the high speed impact shaping press, obtains the pressed compact of required form.In 1120～1250 ℃ of sintering 1～3h, the density of gained iron-base part is 7.58～7.62g/cm to this pressed compact under nitrogen protection atmosphere
3, tensile strength is 700～900MPa.
Embodiment 5: suppress energy for the first time and be 30% of total compacting energy
It is mixing to adopt granularity to be that the water-atomized iron powder of 20～200 μ m and 0.8% graphite powder, 2% nickel powder, 1.5% copper powder, 0.5% molybdenum powder carry out on star core type cylinder machine, obtains uniform iron-based powder mix; Adopt the die wall lubrication technology that lubricant stearic acid zinc evenly is coated in mould and upper punch surface subsequently, when total compacting energy is 1590J, with suppress for the first time energy serve as total compacting energy 30%, to suppress energy for the second time serve as that 70% the energy distribution principle of always suppressing energy is suppressed iron-based powder on the high speed impact shaping press, obtains the pressed compact of required form.In 1120～1250 ℃ of sintering 1～3h, the density of gained iron-base part is 7.55～7.58g/cm to this pressed compact under nitrogen protection atmosphere
3, tensile strength is 650～850MPa.
When total compacting energy was 1590J, in 1120～1250 ℃ of sintering 1～3h, the density of gained iron-base part was 7.45～7.51g/cm to the iron-based pressed compact of employing single pressing preparation under nitrogen protection atmosphere
3, tensile strength is 500～700MPa.
Claims (2)
1, a kind of twice method for press forming for preparing the high-density powder metallurgy iron-base part, adopt high velocity compacted-die wall lubrication technology, it is characterized in that: adopting water-atomized iron powder, copper powder, nickel powder, molybdenum powder and graphite is raw material, the particle diameter of water-atomized iron powder is that 20～200 μ m, content are 95.2～96wt%, copper powder content is 1.2～1.5wt%, nickel powder content is 1.8～2.0wt%, and molybdenum powder content is 0.2～0.5wt%, and content of graphite is 0.5～0.8wt%; At first described water-atomized iron powder, copper powder, nickel powder, molybdenum powder and graphite are carried out mixingly on star core type cylinder machine, obtain uniform iron-based powder mix; Adopt the die wall lubrication technology that zinc stearate evenly is coated in mould and upper punch surface then, then adopt double-press process to prepare iron-base part; Under the certain situation of total compacting energy, suppress energy for the first time and be 10～30% of total compacting energy, suppress energy for the second time and be 70～90% of total compacting energy.
2, a kind of twice method for press forming for preparing the high-density powder metallurgy iron-base part according to claim 1, it is characterized in that: the pressed compact of preparation in 1120～1250 ℃ of sintering 1～3h, obtains highdensity iron-base part under nitrogen protection atmosphere.
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| CN101905323A (en) * | 2010-07-23 | 2010-12-08 | 华南理工大学 | High-speed pressing and forming method for high-density iron-base powder |
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| CN102773481A (en) * | 2012-05-08 | 2012-11-14 | 北京科技大学 | Method of improving performance of iron-based powder metallurgy parts prepared by high velocity compaction |
| CN102935514A (en) * | 2012-10-25 | 2013-02-20 | 无锡中彩新材料股份有限公司 | Powder metallurgical gear and forming method thereof |
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| CN103418787A (en) * | 2012-04-23 | 2013-12-04 | 会田工程技术有限公司 | Method for high-density molding of mixed powder, and device for high-density molding |
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Open date: 20091118 |