Classifications

• • 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
  • B22D19/0009—Cylinders, pistons
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22C—FOUNDRY MOULDING
  • B22C9/00—Moulds or cores; Moulding processes
  • B22C9/06—Permanent moulds for shaped castings
  • B22C9/064—Locating means for cores
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D15/00—Casting using a mould or core of which a part significant to the process is of high thermal conductivity, e.g. chill casting; Moulds or accessories specially adapted therefor
  • B22D15/02—Casting using a mould or core of which a part significant to the process is of high thermal conductivity, e.g. chill casting; Moulds or accessories specially adapted therefor of cylinders, pistons, bearing shells or like thin-walled objects
• • 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
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02F—CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
  • F02F1/00—Cylinders; Cylinder heads 
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02F—CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
  • F02F7/00—Casings, e.g. crankcases

Definitions

• the present invention relates to a technical solution for the composite casting of inserts in a base body made of cast material.
• Casting processes are known in numerous variants.
• the molds are often designed as lost sand molds or metallic permanent molds.
• dormant permanent forms are usually filled without pressure, the shape of the casting is determined by the permanent mold.
• low-pressure mold casting the mold is first filled from below with a slight overpressure via a riser, and the casting is solidified after the mold has been completely filled.
• die casting the melt is pressed into a mold at high pressure and speed. The pressure is maintained until the end of solidification.
• Die casting is primarily suitable for thin-walled castings, such as aluminum, zinc or magnesium alloys.
• Composite castings can also be produced using the above-mentioned casting methods.
• the so-called compound casting designates a production of components made of several materials by input, or encapsulation of component areas with another material.
• Such composite castings are used for different applications, for example for internal combustion engines.
• the conventional gray cast iron cylinder crankcases are increasingly made of light metal, especially aluminum and magnesium alloys. While gray cast iron is suitable both for the crankcase and for the cylinder running surfaces, light metal casting alloys have significantly worse tribological properties. Therefore, additional cylinder liners are cast in the tread area, which consist for example of gray cast iron. Here, the liners must be sufficiently firmly locked in the cylinder crankcase.
• DE 196 05 946 C1 describes a related cylinder liner, which consists of a running layer of molybdenum and an outer layer of aluminum alloy. The outer layer is profiled on its outside. The two layers are formed by thermal spraying on a rotating mandrel and when casting the cylinder crankcase arranged on quills in the mold cylinder liners are connected positively with their profiled outer surface with the casting material.
• oxide layers may also interfere with composite casting.
• an oxide skin on an aluminum component that is to be cast in aluminum casting material may impair the connection to the casting material. This can be avoided according to DE 197 45 725 A1 by destroying the oxide skin on the sprue body by thermal spraying.
• the spray material used is a nickel or molybdenum alloy.
• the detached oxide particles are distributed in the sprayed layer. Partially molten particles protrude from the sprayed layer and improve the bond with the casting material.
• the cohesive bond is to be produced during casting, since this is the most direct and cost-effective variant, which also allows the greatest geometric freedom. Whether a cohesive bond can be produced during casting depends very much on the temperature regime.
• the object of the invention is therefore to provide a technical solution for the production of composite castings, achieved in the manufacturing process with an optimized temperature control between an insert and a base body made of cast material and a permanently good material connection between insert and body is guaranteed.
• composite cast parts may be produced which comprise at least one sprue body and a component geometry which otherwise consists essentially of an aluminum casting alloy.
• the sprue used is an aluminum-based metal-matrix composite (Al-MMC). This AI-MMC casting is freed of its oxide skin before casting and protected from re-oxidation.
• the sprue is provided with a low-melting metal alloy before the sprue. It is essential that the melting point of this alloy is below the melting point of the sprue and the molten metal.
• the application of the metal coating can be carried out in various ways, for example by friction soldering or ultrasonic soldering or mechanical treatment in a solder bath. It is essential here that processes can be used which do not require pretreatments such as pickling or the use of flux during soldering and which eliminate a possible oxide layer on the sprue body and prevent the formation of an oxide layer before and during the casting process.
• the sprue body can be coated both completely and only partially.
• the natural oxide layer located on the sprue body is removed simultaneously with the formation of the metal coating by an external mechanical action, so that there is a material bond between the coating material and the sprue body.
• all coating processes are suitable in which the applied metal layer is applied without intermediate layers and with a material bond to the sprue.
• the metal coating has a dense structure so that the underlying surface of the sprue is closed off from the surrounding atmosphere. Thus, no new oxide layer can form on this surface.
• the thickness of the metal coating is in a range of 10 m to 500 ⁇ , with thicknesses of 100 m to 300 m are useful for most applications.
• the correspondingly pretreated sprue body is then positioned in the casting mold and flows around in the following casting process with a usual gravity and low-pressure casting speed of the molten metal.
• the melting temperature of the coating material is achieved on the sprue body before the flow is stopped.
• this coating is washed off and the molten metal comes into direct contact, to the exclusion of the atmosphere, with the now oxide-free, metallic bright surface of the sprue.
• the flow around the sprue body with the molten metal or the process of washing off the coating from the sprue body can be assisted by the casting process, by aerodynamically optimized design of the gate parts or by maintaining the flow movement after completion of the mold filling.
• additional components are necessary, for example, a stirring device.
• the sprue body can be preheated and / or cooled depending on the respective specific process conditions.
• the tempering can be done for example with heat transfer oil or water or a spray.
• the optional preheating brings the sprue to a temperature that prevents cold running over the sprue and favors the melting of the low melting metal alloy metal coating.
• a targeted melting of the coating can be achieved without, however, melting the sprue body itself.
• the decisive factor is that the sprue is tempered directly (preheated and / or cooled). Direct tempering hot, that the sprue is in direct contact with the heat transfer medium and not as known by applying a cooling iron or a mold, which in turn can also be flowed through by a heat transfer medium.
• the sprue has an accumulation of mass that does not belong to the finished part contour, So has no function in the finished part, is removed after casting, is used for temperature control of the sprue in the casting process and the thermal inertia of the sprue adjusted so that only the low-melting metal alloy is melted on the surface and the casting is not or only slightly melted ,
• the mass accumulation of the sprue itself acts as a heat transfer medium.
• the casting mold has a cooling passage open towards the sprue body, and the sprue body is inserted into this casting mold in such a way that the open cooling channel is closed by the sprue body.
• Parts of the mold and the sprue are tempered by a heat transfer medium (coolant flows).
• coolant flows heat transfer media
• a first coolant stream is supplied at a temperature between 100 ° C and 450 ° C for preheating the mold. Preheating prevents cold runs.
• the coolant flow has no negative pressure during preheating. In the context of the invention, however, it is also fundamentally possible that the coolant flow could have a pressure which is at least 1. 000 Pa lower than the pressure in the mold cavity. This precludes the heat transfer medium from entering the mold cavity. However, with the already available technical solutions, it is not absolutely necessary to realize such a negative pressure in the coolant flow during preheating.
• a second coolant flow is supplied with a temperature which is at least 100 K lower than the temperature of the first coolant flow.
• this coolant flow is not active during preheating and is switched on only at the end of the casting.
• the first and second coolant streams are passed through the same cooling channel.
• the first coolant stream and the second coolant stream have either direct or only indirect contact with the sprue body.
• a direct contact to the Cast body eliminates the heat transfer resistance between the heat transfer medium and the surface of the sprue through the shape and the interface between the mold and sprue. Thus, the temperature of the sprue can be controlled very quickly. Very high cooling rates are possible.
• the surface of the sprue melts. The sprue does not melt. If such a direct contact is realized, however, particular aspects of the water-melt contact are to be considered very accurately.
• the change from preheating to excessive cooling occurs so early that according to the thermal conductivity of the insert, the melting of the surface is prevented only when the entire composite casting area is melted and the melting of the surface is prevented before the sprue is unintentionally thermally stressed. This time is typically from one minute to one minute after pouring.
• the melt in the mold solidifies, the coolant flow is interrupted, the composite casting is removed from the mold and thus the cooling channel is opened again.
• the process described for the production of a composite casting can be slightly modified by the sprue body and / or the casting mold or Parts of the mold to be preheated to a temperature between 100 ° C and 450 ° C before the sprue is inserted into the mold.
• this coolant flow has a pressure which is at least 1. 000 Pa lower than the pressure in the mold cavity and also has direct contact with the sprue body.
• the melt in the mold solidifies, the coolant flow is interrupted, the composite casting is removed from the mold and thus the cooling channel is opened again.
• the composite casting produced according to the method can be configured as a cylinder crankcase, which consists of at least one Zylinderbuchseneinlegeteil and a base body made of a cast metal.
• the cylinder running surface which can be provided with a machining allowance if necessary, during the casting process part of the wall of a cooling channel.
• This cooling channel is further essentially formed by the mold.
• the composite casting produced according to the method can also be designed as a cylinder head, which consists of at least one combustion chamber insert and a base body made of cast metal.
• the combustion chamber surface of the insert part which may also be provided with a machining allowance if necessary, during the casting process part of the wall of a cooling channel.
• This cooling channel is further essentially formed by the mold.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• General Engineering & Computer Science (AREA)
• Molds, Cores, And Manufacturing Methods Thereof (AREA)
• Cylinder Crankcases Of Internal Combustion Engines (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (3)

Family

ID=48747266

Family Applications (1)

Country Status (3)

Cited By (1)

Families Citing this family (3)

Family Cites Families (16)

• 2012
  • 2012-06-04 DE DE201210104820 patent/DE102012104820B4/de not_active Expired - Fee Related
• 2013
  • 2013-05-31 WO PCT/DE2013/100196 patent/WO2013182189A2/fr not_active Ceased
  • 2013-05-31 EP EP13734318.2A patent/EP2855050A2/fr not_active Withdrawn

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