Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C33/00—Making ferrous alloys
  • C22C33/02—Making ferrous alloys by powder metallurgy
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
  • B22F3/10—Sintering only
  • B22F3/1003—Use of special medium during sintering, e.g. sintering aid
  • B22F3/1007—Atmosphere
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
  • C21D1/74—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material
  • C21D1/76—Adjusting the composition of the atmosphere
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
  • H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
  • H01F41/0206—Manufacturing of magnetic cores by mechanical means
  • H01F41/0246—Manufacturing of magnetic circuits by moulding or by pressing powder
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
  • B22F3/02—Compacting only
  • B22F2003/023—Lubricant mixed with the metal powder
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
  • B22F3/24—After-treatment of workpieces or articles
  • B22F2003/241—Chemical after-treatment on the surface
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
  • B22F3/24—After-treatment of workpieces or articles
  • B22F2003/247—Removing material: carving, cleaning, grinding, hobbing, honing, lapping, polishing, milling, shaving, skiving, turning the surface
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
  • B22F2998/10—Processes characterised by the sequence of their steps
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F2999/00—Aspects linked to processes or compositions used in powder metallurgy

Definitions

• the invention relates to a method for producing a Molded part made of a soft magnetic composite material, in particular for use as a magnetic core for a common rail injector, according to the genre of independent claims.
• thermoplastic resin mixed iron powder known, which is particularly for Suitable for the production of magnetic cores.
• an iron powder with phosphoric acid treat this iron powder then with a thermoplastic Resin to mix this mixture at a temperature below the glass transition temperature or Pressing the melting point of the thermoplastic resin, heat the pressed product to the thermoplastic Harden resin, and optionally tempering the obtained Component up to a temperature above the curing temperature of the thermoplastic resin.
• thermoplastic material Polyetherimide known under the trade name Ultem® and oligomers as described in WO 95/33589 and under the trade names Orgasol 3501 and Orgasol 2001 from Elf Atochem, France.
• EP 0 765 199 B1 provides the iron powder with a pressing aid or a lubricant mix that a metal stearate, a wax, a paraffin, a natural or synthetic fat derivative or an oligomer can be of the amide type.
• a pressing aid or a lubricant mix that a metal stearate, a wax, a paraffin, a natural or synthetic fat derivative or an oligomer can be of the amide type.
• lubricants or pressing aids the Kenolube® products from the company Höganäs AB, Sweden, H-wax® from 30%, and Promold® from Morton International, Cincinatti, USA, described using the iron powder in a proportion of preferably 0.2 to 0.8 percent by weight be mixed.
• this starting mixture is known from EP 0 765 199 B1 pressing at a pressure between 400 and 1800 MPa, and then in air at temperatures between 100 ° C and 600 ° C, preferably 200 ° C to 500 ° C, to anneal.
• a powdery powder produced according to EP 0 765 199 B1 Soft magnetic material is sold under the trade name Somaloy TM 500 distributed by Höganäs AB, Sweden and is in the company magazine SOMALOY TM 500, SMC 97-1, Pages 1-11, Höganäs AB, Sweden, characterized in more detail.
• Such soft magnetic composites are also used also in Jan Tengzelius, "Soft magnetic composites for electric motors ", conference proceedings Hagener Symposium, 1.12.2000, pages 211 to 227.
• the object of the present invention was to provide a method by which a powder mixture with a Iron powder in particular as a magnetic core for common rail injectors usable molded part made of a soft magnetic Composite with improved over the prior art mechanical and magnetic properties can be produced is.
• the methods according to the invention have compared to the state technology has the advantage that the molded parts produced afterwards or magnetic cores usual for common rail injectors Magnetic cores made of soft magnetic composite materials for example with mixtures of pure iron powder with polyamide binder, Pure iron powder with polyphenylene sulfide binder or pure iron powder with polyethylene binder are, especially with regard to mechanical strength, density, saturation polarization, magnetic Permeability, the specific electrical resistance, superior to surface hardness and flexural strength are.
• the molded parts produced according to the invention in the form of magnetic cores compared to magnetic cores made of polyphenylene sulfide-bonded composite material have an increased density of more than 7.3 g / cm 3 by at least 0.2 g / cm 3 , and they also have a significantly improved surface hardness and statistical bending strength, which is particularly evident in the critical area of the pole faces in an improved edge breaking strength under permanent load. In addition, they are less prone to material breakouts and less diesel fuel penetrates the workpiece structure.
• the molded parts produced according to the invention in the form of magnetic cores typically have a magnetic force of 95 N to 103 N, while corresponding molded parts made of polyphenylene sulfide-bonded composite material only reach about 80 N.
• the molded parts produced according to the invention when used as a magnetic core in common rail injectors are significantly higher Switching dynamics, especially one reduced by approx. 20 ⁇ s Switch-on time, a reduced energy requirement, approx. 50% higher mechanical strength, better mechanical Machinability and greater insensitivity to Manufacturing fluctuations in manufacturing.
• the gas atmosphere during Annealing a gas mixture with an oxygen content of 2 vol% is up to 7 vol%, being a mixture of air and nitrogen or a mixture of air and a rare gas, the proportion the air between 40 vol% and 10 vol%, in particular 10 vol% to 30 vol%, is particularly simple and inexpensive can be produced.
• Another improvement in magnetic and mechanical Properties of the molded parts obtained, particularly with regard to their density, is achieved when the annealing of the pressed parts in a two-stage process is, after pressing the starting mixture the molded part initially at a relatively low temperature annealed, then in a die tool or by hot plan forming pressed again, and finally at a higher one Temperature is annealed again.
• Molded parts made of a soft magnetic composite is preferably an oxide-bonded material, i.e. during the tempering process, one of the starting mixtures decomposes for example added metal stearate a metal oxide so that the presence of Oxygen at grain boundaries form iron oxide bridges, which the Effective improvement in structural cohesion are according to the invention manufactured molded parts over such Polymer-bonded soft magnetic composites too contain at least almost no organic components.
• the molded parts produced according to the invention have their higher density also has a lower porosity, which leads to a significantly improved thermomechanical long-term stability, especially against hot diesel fuel leads.
• a first embodiment of the invention is based on a Starting mixture with a pure iron powder and a pressing aid from the Höganäs company, Sweden, is marketed under the trade name Somaloy TM 500.
• the pure iron powder used is one high-purity iron powder with a phosphated surface, as described in EP 0 765 199 B1 as a lubricant Pressing aids, selected from the group of metal stearates, waxes, paraffins, natural or synthetic fat derivatives or the amide-type oligomers is clogged.
• the pure iron powder is preferred together with the under the molding aid known from the trade name Kenolube® Höganäs AB, Sweden.
• Kenolube® which is essentially an amide wax and contains zinc stearate in a proportion of 0.4% by weight 0.7% by weight, preferably 0.5% by weight to 0.6% by weight, of the pure iron powder added and with this to the starting mixture mixed.
• the starting mixture is then in a common die tool preferably at room temperature at a pressure between 600 MPa to 900 MPa, in particular 700 MPa to 800 MPa, for example in the form of a magnetic core pressed for common rail injectors.
• the molded part obtained is at temperatures between 380 ° C to 450 ° C, especially at approx. 425 ° C, over a period of 10 min to 120 min, in particular 30 min to 60 min, in a nitrogen-air mixture or in a Noble gas-air mixture annealed, the proportion of air between 50 vol% and 5 vol%, in particular 10 vol% to 30 % By volume, for example 20% by volume.
• the added Press aids partly decomposed and partly in one binding oxide converted.
• a mixture of an inert gas with oxygen for example a Nitrogen-oxygen mixture or an argon-oxygen mixture, be used, which has an oxygen content between 1 vol% and 10 vol%, in particular 2 vol% to 7 vol%, contains.
• the molded parts obtained after the tempering are preferred a final mechanical surface treatment, for example, subjected to grinding. This leads to improved mechanical properties and an improved Long-term stability of the molded parts obtained.
• the measured Magnetic force on such magnetic cores is usually approx. 5% to 10% increases.
• a second embodiment of the invention provides that deviates from the exemplary embodiment explained above after compressing the starting mixture to the First a tempering step at one temperature from 150 ° C to 400 ° C, especially at temperatures between 230 ° C and 310 ° C.
• This first tempering step can take place in air or an inert gas atmosphere such as an inert gas atmosphere or a nitrogen atmosphere respectively. However, it is preferably carried out analogously annealing in the first embodiment, in a gas mixture from an inert gas and oxygen, the proportion of the oxygen in the gas mixture between 10 vol% and Is 1% by volume.
• the gas atmosphere is particularly preferred in this exemplary embodiment again a mixture of air and nitrogen, the proportion of air between 50 vol% and 5 vol%, in particular 10 vol.% To 30 vol.%, For example 20 vol.%, is.
• the pressed, tempered molded part After the first tempering step, the pressed, tempered molded part another pressing at a pressure between 600 MPa to 900 MPa, in particular 700 MPa to 800 MPa, carried out at room temperature.
• this post-forming can also be carried out using hot plan forming in a suitable die tool at elevated temperature take place as described for example in DE 100 05 551.6 is.
• the molded parts obtained after the tempering are preferred then analogous to the first embodiment of a final one mechanical surface treatment, for example grinding.
• a molded part made of a soft magnetic composite material made of the phosphated pure iron powder Somaloy 500 with 0.6% by weight Kenolube according to the above exemplary embodiments has a statistical bending strength of at least 25 N / mm 2 , determined on test bars according to ISO 3327, and a surface hardness HB 2, 5 / 31.25 from at least 70.
• rings with an outer diameter of 40 mm, an inner diameter of 30 mm and a height of 5 mm have a magnetic polarization J 100 of at least 1.4 Tesla at 100 A / cm and a saturation polarization J s of at least 1.5 Tesla 500 amperes / cm, a coercive field strength H cB of a maximum of 3.0 amperes / cm, a maximum permeability ⁇ max . of at least 450 and a total loss ⁇ H + ⁇ W at 1 Tesla and 50 Hz of max. 8 W / kg measured.
• a saturation polarization of more than 1.7 Tesla and a maximum permeability of approx. 500 is achieved with a specific electrical resistance of approx. 10 ⁇ m.
• the density of the molded parts obtained is at least 7.30 g / cm 3 , it being possible to increase the density to up to approximately 7.5 g / cm 3 by the additional post-forming in a die tool or the additional hot plan forming.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Manufacturing & Machinery (AREA)
• Power Engineering (AREA)
• Organic Chemistry (AREA)
• Materials Engineering (AREA)
• Physics & Mathematics (AREA)
• Crystallography & Structural Chemistry (AREA)
• Thermal Sciences (AREA)
• Soft Magnetic Materials (AREA)
• Powder Metallurgy (AREA)
• Heat Treatment Of Articles (AREA)

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• 2001
  • 2001-02-10 DE DE10106172A patent/DE10106172A1/de not_active Ceased
• 2002
  • 2002-01-19 EP EP02001397A patent/EP1231003B1/fr not_active Expired - Lifetime
  • 2002-01-19 DE DE50213306T patent/DE50213306D1/de not_active Expired - Lifetime
  • 2002-02-11 US US10/074,175 patent/US7175794B2/en not_active Expired - Fee Related

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