Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22C—FOUNDRY MOULDING
  • B22C9/00—Moulds or cores; Moulding processes
  • B22C9/10—Cores; Manufacture or installation of cores
  • B22C9/101—Permanent cores
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
  • B21J5/00—Methods for forging, hammering, or pressing; Special equipment or accessories therefor
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
  • B21J5/00—Methods for forging, hammering, or pressing; Special equipment or accessories therefor
  • B21J5/002—Hybrid process, e.g. forging following casting
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D19/00—Casting in, on, or around objects which form part of the product
  • B22D19/04—Casting in, on, or around objects which form part of the product for joining parts
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D21/00—Casting non-ferrous metals or metallic compounds so far as their metallurgical properties are of importance for the casting procedure; Selection of compositions therefor
  • B22D21/02—Casting exceedingly oxidisable non-ferrous metals, e.g. in inert atmosphere
  • B22D21/04—Casting aluminium or magnesium

Definitions

• the invention relates to a method for producing a motor vehicle component, in particular a chassis component.
• Cobapressclar This is a cast forging process in which a cast billet is reforged once.
• the so-called counter-pressure casting is also used in the production of suspension components.
• an overpressure is generated during the solidification phase of the light metal casting in the mold (mold).
• the EP 0 315 566 B1 discloses a method of making a ceramic-metal composite and such a composite body. For the manufacture of a ceramic article is formed, which is provided on at least part of its surface with a coating material. Then the object is covered with a molten metal. The molten metal is then solidified to obtain the ceramic-metal composite.
• the coating consists of burnt plaster with filler material.
• the DE 199 29 761 A1 as well as the DE 199 18 908 A1 disclose a core for cast components and a manufacturing process therefor.
• Light metal or light metal alloys are becoming increasingly important as a lightweight construction material in automotive engineering, especially with regard to lightweight chassis components. Due to the lower modulus of elasticity compared to steel, the necessary component rigidities require special shell-like structures in order to realize the lightweight potentials of the light metal materials.
• the shell-like structures are produced by the fact that instead of forged blanks with full cross section of extruded profiles in drop forging or in the form of near-net shape castings with full cross section in the Cobapress compiler as Schmiederohlinge component-shaped castings with core bodies made of special, ultra-light, heat-resistant and thermally resistant materials - so-called hybrid cores , which remain as permanent cores in the chassis part and endure the subsequent drop forging processes, heat treatments, mechanical processing and the stresses as a motor vehicle component, in particular chassis component.
• the basic components for core bodies of the prior art are sands as refractory fillers (85-98%), a binder (2-10%) and optionally a hardener.
• the binders are organic (synthetic resin based) or inorganic (clay, water glass) natural.
• the most used Synthetic resin binders are phenolic and furan resins.
• the development of new inorganic binder systems is well advanced and in industrial testing.
• the basic principle of these core bodies is the highest possible compression or compression, whereby air inclusions are reduced purely mechanically.
• the spaces between the compacted sands and fillers are filled with suitable binders so that only minimal, unavoidable air pockets remain in the core bodies.
• these solutions inevitably lead to an increased density of the core material, which is usually much higher than that of light metal, such as aluminum. Accordingly, the weight of the core body is correspondingly high.
• Non-compacted core bodies have a high porosity with corresponding air inclusions.
• these air pockets are heated and expanded accordingly. From those surface areas of the core body, which are not yet enclosed by the liquid light metal, the heating air from the porosities can still escape via the vent and feed openings of the casting system.
• the core bodies are enclosed by liquid light metal, the expanded air can only escape through the solidifying casting and / or forms pore-like air inclusions of different characteristics during solidification in the casting.
• Such porosities due to core outgassing are undesirable and must be minimized as they adversely affect the mechanical properties and quality of the castings.
• the invention is based on the object of providing a method for producing qualitatively improved, lightweight construction and heavy-duty motor vehicle components, in particular chassis components.
• core body prefabricated bodies made of lightweight, heat-resistant and thermally resistant, mineral materials are used.
• the core body must withstand the subsequent drop forging processes, heat treatments, mechanical processing and the stresses in the motor vehicle and remain as a permanent core in the motor vehicle component.
• the sponge-like porous and comparatively very high air fractions containing core body are prepared so that they do not outgas as much as possible during the casting process and the solidification, i. at the high casting temperatures do not give off gas to the casting material. In this way, the negative-acting porosity in the casting can be avoided.
• the invention provides to heat the core body so that the air or gas fraction is expelled in the pores of the core body. Subsequently, the core body with a light metal casting, in particular cast aluminum, cast around and produced in this way a blank. This blank is processed by forging and so formed the motor vehicle component.
• the core bodies are heated to a temperature at which most of the gas present in the core body is expelled, at least. Depending on the material of the core body and porosity, the heating is carried out to a temperature between 100 ° C and 800 ° C, in particular to a temperature between 300 ° C and 700 ° C.
• the core body is heated to a temperature which, with a deviation of +/- 100 ° C corresponds to the temperature of the light metal casting, which has the light metal casting during the casting of the core body.
• the outer shell of the forging blank and the motor vehicle component formed therefrom consists of light metal casting.
• aluminum or aluminum alloys or magnesium or magnesium alloys are used.
• a core body of a mineral material used which is more heat resistant and lighter than the material of the outer body made of light metal casting.
• the heat or temperature resistance is such that the core body can be embedded in molten hot light metal casting.
• Aluminum or aluminum alloys have a specific gravity of about 2.7 g / cm 3 and a melting point of about 660 ° C.
• Magnesium or magnesium alloys have a specific gravity of about 1.7 g / cm 3 and a melting point of about 650 ° C.
• a material is used as the core body with a fire resistance to temperatures of 800 ° C and higher, in particular a melting point between 1300 ° C and 1400 ° C.
• vermiculite is vermiculite.
• the blanks produced according to the invention are used as forging blanks for the subsequent forging process, in which by appropriate degrees of deformation a reliable elimination of the porosities by Swallowing and merging takes place. Due to the thermal pretreatment, the porosity was minimized to the extent possible to ensure the desired high and stable mechanical characteristics for the intended use of the finished forgings, in particular as safety parts in chassis.
• the solution of the present invention is to heat the finished shaped core bodies to a suitable preheating temperature, preferably immediately prior to positioning in the mold, whereby the gases contained can expand and escape from the core before the casting takes place.
• a suitable preheating temperature preferably immediately prior to positioning in the mold, whereby the gases contained can expand and escape from the core before the casting takes place.
• the preheating temperatures are in detail on the concrete technological conditions such as casting temperature, type of mold, e.g. Mold or sand, the cycle time of the casting process, in particular the time between preheating and casting and other relevant factors interpret.
• the preheating of the core body can be done in separate, the casting process spatially and temporally suitably upstream ovens or other suitable heating devices. But it can also be done directly during the positioning or already in position of the core body to the molds by means of suitable heat radiators, heat hoods, etc. Depending on the specific technological conditions, preheating temperatures between 300 ° C and 700 ° C, but occasionally also lower or higher, are to be expected.
• the core body before or after heating with a seal is provided.
• the core bodies can be provided with a coating before or after the heating. This is called surface preparation.
• the degasification is prevented by sealing by suitable means, e.g. Water glass, the gas leakage from the hybrid core prevented or hindered to a tolerable extent.
• suitable means e.g. Water glass
• the sealing may take place on the cold or preheated core body.
• a surface roughening coating may be carried out in the form of carbon black on the surface of the core body.
• these soot deposits smooth the core surface and, on the other hand, because of the high carbon content, they produce separating effects compared to liquid aluminum.
• the technically usable effects would be a quality-relevant smoothing of the surfaces, improvement of the lubricity compared to the flowing light metal during the casting phase as well as the easier separability of unavoidable outgassing from the hybrid core surface. Due to the easier separability of any outgassing in the form of bubbles etc. from the core surface, they can quite quickly be washed away in the liquid phase of the light metal and flowed out of the casting into the feeder and vent areas.
• the degassing of the porous core body is minimized. This is done by a thermal preparation. In addition, a sealing preparation and / or surface preparation can take place.
• the core body treated according to the invention are cast in a light metal casting and embedded in these. The blanks produced in this way are formed by forging into motor vehicle components.
• the core bodies are arranged in particular in those component areas of the later motor vehicle component, which should have a lower strength with the same or higher stiffness than another component area.
• the positioning of the core body takes place in adaptation to the later loads of the finished motor vehicle component.
• the core bodies are provided where primarily higher stiffness and not maximum strength is required. In coordination with the component properties and their contour, the positioning of the core body already takes place in the blank.
• the forging technology for example, by swaging, is specifically designed so that when forging defined densifications of the light metal material and the core body done, with the required mechanical properties of the motor vehicle component can be achieved or adjusted.
• the temperatures are defined by the forging process. In practice, forging temperatures between 400 ° C and 600 ° C are assumed.
• the forging technology processing of the blank can be carried out following the casting production of the blank using the heat from the casting process. In principle, however, a cooled blank for the forging process can be heated to forging temperature.
• the method according to the invention is suitable for the production of suspension components.
• suspension components Such areas of a chassis component in which the highest Festigekeiten are required, are carried out, as usual, with a solid cross-section.
• the material gets in the forging in these Component areas by appropriate material flow and material compaction highest strengths.
• the invention provides highly stressed motor vehicle components, in particular suspension components, with yield strengths of 280 MPa and more at elongations at break of about 10%, which are reduced in weight compared to comparable conventional motor vehicle components.
• the weight of the motor vehicle components can be reduced with the method according to the invention over the prior art. This is not only a major factor in reducing manufacturing costs, but also an important contribution to reducing chassis masses, especially unsprung masses, which have a high impact on fuel economy and ride comfort.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Forging (AREA)
• Body Structure For Vehicles (AREA)

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Cited By (3)

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Citations (10)

• 2009
  • 2009-11-24 DE DE200910054315 patent/DE102009054315A1/de not_active Ceased
• 2010
  • 2010-08-19 EP EP10008638A patent/EP2332671A1/fr not_active Withdrawn

Patent Citations (10)

Non-Patent Citations (2)

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