Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D17/00—Pressure die casting or injection die casting, i.e. casting in which the metal is forced into a mould under high pressure
  • B22D17/007—Semi-solid pressure die casting
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D17/00—Pressure die casting or injection die casting, i.e. casting in which the metal is forced into a mould under high pressure
  • B22D17/14—Machines with evacuated die cavity
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D17/00—Pressure die casting or injection die casting, i.e. casting in which the metal is forced into a mould under high pressure
  • B22D17/20—Accessories: Details
  • B22D17/22—Dies; Die plates; Die supports; Cooling equipment for dies; Accessories for loosening and ejecting castings from dies
  • B22D17/24—Accessories for locating and holding cores or inserts
• • 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

Definitions

• the invention relates to a method for producing molded metal parts, in particular lightweight parts made of light metal, and to the molded parts produced by this method and their use in light metal structures.
• foamed metallic materials are materials that secure an ever wider distribution area.
• foamed metallic materials are characterized by light construction, rigidity, compressive strength, improved mechanical and acoustic damping and. a. out.
• the production of components from foamed metallic materials is also known.
• GB 892934 relates to the production of complex structures with a foamed metal core and a closed, non-porous surface.
• DE 198 32 794 Cl describes a method for producing a hollow profile which is filled with metal foam. This method comprises the steps of pressing the hollow profile made of a shell material with an extrusion press, which has an extrusion tool with a die and a mandrel, feeding the metal foam made of a foam material through a feed channel to the hollow profile which is formed in the mandrel.
• DE 297 23 749 UI discloses a wheel for a motor vehicle which comprises at least one metallic foam core which is arranged exposed to the inside of the wheel and has a cast wall towards the outside of the wheel. The foam core made of aluminum foam is placed in a mold for casting the wheel and positioned so that the outer cast skin is created between the mold and the foam core during casting.
• DE 195 02 307 AI describes a deformation element in the housing of which a filling made of an aluminum foam is provided as an energy absorber.
• the housing can be made of metal or plastic.
• the packing is a mere insert without a material connection to the housing.
• a core made of aluminum foam is introduced into a die, which remains after the aluminum has been pressed into the mold in the component made of die-cast aluminum (principle of the lost core).
• the aluminum foam used arises from a mixture of aluminum powder with a blowing agent and is produced in a manner known per se in a multi-stage process (such a process is described, for example, in the article “Economical production techniques for the production of aluminum foams, aluminum , 76er year 2000, page 491 ff).
• the aluminum foam bodies produced in this way are then inserted into a casting mold with closed porosity, the core made of foamed aluminum at the little-stressed points is supported or fastened to the inner wall of the casting tool so that with a uniform distance in the desired wall thickness remains between the core and the tool. Only by maintaining this distance between the core piece and the tool is the formation of a closed and sufficiently stable wall in the resulting molded part guaranteed.
• the process used for attaching core supports to support cores in mold cavities has long been common practice in foundry processes (see Foundry Encyclopedia, 17th edition 1997, Stephan Hasse, page 658 and page 640 below).
• the requirements for the cores to be used are not only that they must either be sufficiently pressure-stable for use in die casting processes or, when used in casting filling processes at low speed, must be correspondingly temperature-resistant to liquid or semi-liquid metal in order not to be in their position to change the shape or to release a part of the volume they used during the filling process, but also to meet the requirement for precise support within the mold cavity and is sometimes very complex. That is e.g. B. recognizable from the wide range of commercially manufactured core supports (see e.g. delivery range from Phoebus Kern span GmbH & Co. KG, Dortmund) and also from the use of core support gluing devices as aids for fixing the core bodies in a casting mold.
• the invention accordingly relates to a method for producing molded metal parts, which is characterized in that metal bodies with a surface that is closed on all sides and a hollow structure on the inside are placed in a mold and the remaining mold cavity is then filled with a metal or a metal alloy.
• the surface area of the metal body preferably has an average density higher by a factor of 1.5 to 20, preferably 3 to 15, particularly preferably 5 to 10, than the interior of the metal body.
• the metal structure enveloping the metal body (core) has a higher density than the average density of the metal body used, the molded part produced therefrom is correspondingly reduced in weight. If it has essentially the same density, there is of course no reduction in weight, but a possibly more expensive material can be produced more cheaply by embedding a cheaper shaped body.
• a metal foam core is particularly suitable as the metal body, which advantageously has an integral foam structure.
• the metal body is usually cast with a molten metal, which can be done, for example, in a die casting machine.
• Light metals in particular aluminum or aluminum alloys, are particularly suitable for the process according to the invention, it being possible for the metals or alloys used to produce the moldings to be different from those of the moldings.
• a metal integral molded foam is preferably used as the metal body which, in contrast to the foam bodies usually described in the literature, does not have a uniform foam morphology along its cross section. (The production of such a metal body is described in DE 101 04 339.2.) Instead, it is a molded foam body that can be produced in the outer zones true to the contour and whose outer shell is close to the density of the metal or metal alloy used. This metallic integral foam thus represents a real gradient material. In the interior of the molded body, however, the density is reduced by the occurrence of gas bubbles, so that the average density of the entire molded body is below the theoretical density of the metal or metal alloy used (FIG.).
• the average density per cubic millimeter of the outer millimeter layer of the molded body is higher by a factor of 1.5 to 20, preferably 3 to 15, particularly preferably 5 to 10 than the average density in the interior of the molded body.
• Shaped bodies of this type can be produced, for example, by die casting directly from the melt with the addition of a blowing agent.
• the thickness of the outer skin of the shaped body and thus the temperature and pressure stability can be adapted according to the respective use by suitable variation of the process parameters, while at the same time the contour accuracy of the resulting shaped body enables exact positioning during further processing. So z. B. the metal bodies to be used according to the invention can be used to reduce the weight of a complicated metal casting by using it as cores remaining in the end product.
• such cores due to their industrial manufacturing process to reduce the cost of the end bodies, because they can be manufactured inexpensively firstly and secondly they can be made from a cheaper material than the metal sheath surrounding them later. Due to their special pressure and temperature stability, such cores are not only for very fast processes such as the die casting process, but of course also for slow ones and thus The temperature load on the core body can be used in very demanding processes. This results in a wide range of application areas, such as. B. squeeze casting, and even the use in casting processes that work with incompletely liquid metals or metal alloys, such as. B. Thixo-Casting (Semi Solid Metal Casting).
• the practically closed outer skin of the integral molded foam body to be used according to the invention also enables it to be used in vacuum casting processes, since the quality of the surface that is created enables the casting mold to be evacuated in the process of final body production according to the invention, without continuous gas leaks from the interior of the core body and to a disruptive extent to observe a concomitant reduction in the vacuum.
• the integral mold foam core can be introduced into the mold used either manually or according to other customary industrial processes, eg. B. by robots.
• the subsequent casting and thus the formation of the weight-reduced target workpiece can also be carried out with metals or metal alloys with a higher melting point or at a higher processing temperature than the melting point of the core material due to the temperature and pressure stability of the outer core skin.
• Such a procedure that uses higher melting enamelling materials even has the advantage that the outer surface of the core body is partially melted and thus an intimate metallic bond is formed between the core material and the enveloping shell material of the end workpiece in the subsequent solidification process of the end body.
• the excellent pressure stability of the core body used means that post-treatment of the final workpiece is generally not necessary.
• the invention is described in more detail below in an exemplary embodiment.
• the single figure shows a section of an integral molded foam suitable as a core.
• a vehicle part should be made from an aluminum material as an integrally foamed metal body.
• a casting chamber of a die casting machine was filled with a corresponding amount of molten metal in a first step.
• Magnesium hydride in powder form was added to the liquid metal as a foaming propellant in the closed casting chamber.
• the mixture of blowing agent and molten metal began to be quickly inserted into the mold cavity.
• the mold cavity was underfilled in a defined volume. The resulting turbulence ensures thorough mixing in the mold cavity and foaming of the cavity.
• the “shot” took place before the foam was formed, the foaming process took place “in situ” in the mold cavity. It was quickly foamed into the cold form.
• the component had a mass of only approx. 40% compared to conventional die-cast parts made of the same material.
• the metal body produced according to the example was then used as the core in a larger mold is inserted and the mold is closed. Then a metal melt was pressed out of the casting chamber of the die casting machine into the mold cavity in accordance with the usual die casting process. In this filling process, the mold cavity was completely filled, and excess metal was removed from the connecting channel and the end of the casting chamber after the molded body had cooled.
• the result of this process was a weight-reduced molded part, which had cavities in the area of the inserted core body, but corresponded to a full casting in the area of the structures not filled by the core.
• the molded body produced according to the example had a lower density and better vibration absorption behavior than the corresponding solid material comparison body.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Molds, Cores, And Manufacturing Methods Thereof (AREA)
• Manufacture Of Alloys Or Alloy Compounds (AREA)
• Forging (AREA)

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Applications Claiming Priority (3)

Publications (2)

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• 2001
  • 2001-05-16 DE DE10123899A patent/DE10123899A1/de not_active Withdrawn
• 2002
  • 2002-05-03 WO PCT/EP2002/004866 patent/WO2002092261A2/fr active IP Right Grant
  • 2002-05-03 CA CA002443828A patent/CA2443828C/fr not_active Expired - Fee Related
  • 2002-05-03 AT AT02742936T patent/ATE366630T1/de active
  • 2002-05-03 ES ES02742936T patent/ES2290316T3/es not_active Expired - Lifetime
  • 2002-05-03 EP EP02742936A patent/EP1472026B1/fr not_active Expired - Lifetime
  • 2002-05-03 AU AU2002342227A patent/AU2002342227A1/en not_active Abandoned
  • 2002-05-03 JP JP2002589184A patent/JP2005500162A/ja active Pending
  • 2002-05-03 DE DE50210474T patent/DE50210474D1/de not_active Expired - Lifetime
  • 2002-05-14 US US10/146,701 patent/US6854506B2/en not_active Expired - Fee Related
• 2009
  • 2009-03-16 JP JP2009062550A patent/JP2009166130A/ja active Pending

Non-Patent Citations (1)

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