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
  • B22D19/0027—Cylinders, pistons pistons
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22C—FOUNDRY MOULDING
  • B22C9/00—Moulds or cores; Moulding processes
  • B22C9/22—Moulds for peculiarly-shaped castings
  • B22C9/24—Moulds for peculiarly-shaped castings for hollow articles
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D18/00—Pressure casting; Vacuum casting
  • B22D18/06—Vacuum casting, i.e. making use of vacuum to fill the mould
• • 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
  • B22D19/14—Casting in, on, or around objects which form part of the product the objects being filamentary or particulate in form
• • 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
  • B22D21/002—Castings of light metals
  • B22D21/007—Castings of light metals with low melting point, e.g. Al 659 degrees C, Mg 650 degrees C
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
  • F02B23/00—Other engines characterised by special shape or construction of combustion chambers to improve operation
  • F02B23/02—Other engines characterised by special shape or construction of combustion chambers to improve operation with compression ignition
  • F02B23/06—Other engines characterised by special shape or construction of combustion chambers to improve operation with compression ignition the combustion space being arranged in working piston
  • F02B23/0603—Other engines characterised by special shape or construction of combustion chambers to improve operation with compression ignition the combustion space being arranged in working piston at least part of the interior volume or the wall of the combustion space being made of material different from the surrounding piston part, e.g. combustion space formed within a ceramic part fixed to a metal piston head
• • 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
  • F02F3/00—Pistons 
• • 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
  • F02F3/00—Pistons 
  • F02F3/0084—Pistons  the pistons being constructed from specific materials
• • 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
  • F02F3/00—Pistons 
  • F02F3/28—Other pistons with specially-shaped head
  • F02F3/285—Other pistons with specially-shaped head the head being provided with an insert located in or on the combustion-gas-swept surface
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16J—PISTONS; CYLINDERS; SEALINGS
  • F16J1/00—Pistons; Trunk pistons; Plungers
  • F16J1/01—Pistons; Trunk pistons; Plungers characterised by the use of particular materials
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
  • Y02T10/00—Road transport of goods or passengers
  • Y02T10/10—Internal combustion engine [ICE] based vehicles
  • Y02T10/12—Improving ICE efficiencies

Definitions

• the invention relates to a method for producing a piston according to the preamble of claim 1.
• Fluid energy machines perform in the piston in cylinders transmitted via push rods periodic translational movement, are known in mechanical engineering as reciprocating engines.
• the most common type of piston engine represents the reciprocating engine, which converts the change in volume of a gas in the described linear movement of the piston and a connecting rod and a crank further into a rotational movement.
• the piston comprises a combustion bowl for this purpose.
• Suitable pistons are produced according to the prior art regularly by means of a primary molding process, in particular by means of specialized casting techniques.
• the problem here is the compensation of the occurring during operation of the engine extremely high thermal load in the edge region of the combustion bowl, which can lead to the formation of cracks in the piston under unfavorable conditions.
• the use of cooled ring carriers is known in view of this problem.
• the trough edge is also reinforced by the pouring of ceramic fibers.
• Kokilleng think compiler for this purpose sometimes a pressurization after the mold filling used to ensure the complete infiltration of the ceramic fibers through the molten aluminum and thus to promote the integration of the ceramic fibers in the metal structure.
• a corresponding method is known from the embodiment according to claim 4 of DE 10 2004 056 519 A1.
• an annular Faserpreform is first attached to reinforce the edge of the combustion bowl in the mold.
• a liquid aluminum or aluminum alloy melt is introduced into the mold, from which the Faserpreform infiltrated and is formed in the mold during the casting process in the trough edge.
• the piston blank produced in this way is subsequently heat treated before the piston is finished by means of a machining process.
• the pressure difference between the aluminum alloy melt and the Faserpreform is thereby caused on the one hand, that the Faserpreform of suction tubes (in addition to possibly existing further fixings) is held in the mold, wherein in the suction such a negative pressure prevails that sucked from the aluminum alloy melt in the Faserpreform and infiltrate the Faserpreform.
• the connected vacuum pump contributes by lowering the remaining gas pressure to preferably less than 0.1 bar to completely vent the voids in the Faserpreform before the penetration of the melt and thereby preventing the formation of air pockets.
• the melt is pressurized by applying an overpressure to the melt in the mold, typically up to 20 bar.
• This is intended to produce a very high-quality and, in particular, highly resilient piston, which is subsequently free of trapped air in the infiltrated fiber preform.
• the solidification behavior of the aluminum melt infiltrating the fiber preform proves to be critical. Premature solidification of the melt within the Faserpreform before completion of infiltration releases unwanted voids.
• the melt flows through the suction pipe after infiltration, it can enter the vacuum pump and clog or narrow channels there. In this respect, premature as well as delayed hardening of the melt can significantly impair the quality of the process result.
• the invention is therefore based on the object to improve a generic manufacturing process to the effect that it allows a defined solidification of the melt used, without causing air bubbles in the Faserpreform.
• the invention is therefore based on the idea of providing the intake pipes also used to hold the fiber preform in the casting mold with a specially designed section which promotes defined solidification of the melt in the desired section of the suction pipes and thereby clogs the suction pipe for the inflowing melt.
• the stream of the melt is brought to a standstill within the suction tube only after the complete infiltration of the fiber preform by a specifically induced solidification.
• Such a "Sollerstarrungsabites" can thereby be realized on the one hand by means of a thermal, on the other hand by means of a geometric approach.
• the specially designed section of the suction tube is designed such that, in particular without further components or inserts, that is intrinsically, a defined premature solidification of the melt favored.
• thermal means the solidification of the melt can be brought about by a local cooling of the suction tube.
• the choice of a suitable material can accelerate the solidification of the melt, provided that the corresponding material has one of the melt in relation to increased thermal conductivity.
• a hypoeutectic aluminum-silicon melt for example, the use of copper as a material of the tube.
• a geometric solution of the problem can be done in different ways.
• the first thing to think about is the formation of a constriction in the course of the intake manifold, which locally reduces its flow cross-section.
• a similar effect can be achieved by means of a bent or kinked pipe section, by means of combinations of cross-sectional constrictions and / or directional changes, or generally by any labyrinthine obstruction along the draft path.
• Fig. 1 is a plan view of the bottom of a according to the invention
• Fig. 2 shows a section through the mold along the axis of the piston with two different embodiments of the suction pipes according to the invention, which are shown in the right and left side of the figure.
• Figures 1 and 2 illustrate the implementation of the manufacturing method according to an embodiment of the invention, in which case a specific light metal melt is used as the base material of the piston 1 to be produced. It is preferably a hypoeutectic aluminum-silicon alloy (AISi alloy), which, in view of the mechanical stress to be expected during operation of the piston 1, has undergone a refining microstructural influence.
• AISi alloy hypoeutectic aluminum-silicon alloy
• the edge of the combustion bowl 2 on the piston head 5 is reinforced by means of a Faserpreform 3.
• a sufficiently large pressure difference between light molten metal and Faserpreform 3 ensures that the Faserpreform 3 is completely infiltrated with the light metal melt used in the casting before it solidifies.
• the fibers of the fiber preform 3 are formed as short fibers of a ceramic material, for example of aluminum oxide (Al 2 O 3 ), as it is known above all. is also referred to in the technical field as electrocorundum (ELK) and is based on the clay or silica fiber products marketed under the brand name Saffil. Alternative embodiments may use a fiber orientation that differs from the random-planar standard without departing from the scope of the invention.
• the Faserpreform 3 in the form of an annular body with a rectangular cross-section is prepared by the fibers are first prepared to an aqueous suspension containing a binder.
• the suspension is filled into a water-permeable, the shape of the Faserpreform 3 corresponding form in which the water is separated from the suspension.
• the resulting body in the form of Faserpreform 3 is dried and can be mechanically repressed to improve its strength.
• the aim here is a proportion of fibers per unit volume of 10% to 20%.
• the Faserpreform 3 is preheated to exclude moisture inclusions.
• a gravity die casting method is used in this case, in which the light metal melt passes through a ladle by gravity into the mold serving as a mold.
• a pressure between 0.5 bar and 20 bar is used, wherein a not shown in Figures 1 and 2, by means of obliquely tightened retaining pins locking frame of the casting tool for secure recording of the pressure forces.
• the Eing manmaschine be like, the Faserpreform 3, preferably in combination with a salt core and / or a ring carrier or a cooled ring carrier, fixed in the mold at the designated places. Subsequently, the mold is closed with a lid having two radially outer suction pipes 10, 1 1, which are connected to a vacuum pump, not shown, and open at such locations in the interior of the mold, that at the openings of the suction pipes 10, 1 1 the Faserpreform 3 rests and is held by the prevailing in the tubes 10, 1 1 negative pressure at the designated location.
• the light metal melt is then introduced into the mold, wherein the pressure prevailing in the suction pipes 10, 1 1 negative pressure causes the held on the suction pipes 10, 1 1 Faserpreform 3 is infiltrated by the light metal melt.
• the opening into the Faserpreform 3 suction tubes 10, 1 1 are resiliently biased against the Faserpreform 3 and cooled to a temperature that significantly accelerates the solidification of the light metal melt.
• suction tubes 10, 1 1 with a high thermal conductivity which promote rapid solidification of the melt by heat dissipation.
• At each suction pipe 10, 1 1 1 at least a portion 13, 14 is provided, which accelerates the solidification of entering the suction pipe 10, 1 1 melt.
• the section can be designed as a constriction or as a bend.
• the particular copper suction pipes 10, 1 1 are optimized with the aim of accelerated solidification of the light metal melt.
• the suction tubes 10, 1 1 each have a single wave train with a local offset 4 of the tube axis, which on closer inspection consists of kinks or bends of the tube axis. In the region of the bend or the offset 4, by approaching the opposite tube walls in each case to a local cross-sectional constriction. Changes in direction of the pipe axis by bending but can also be used without change in cross section according to the invention, as well as pure constrictions or cross-sectional changes without changing the direction of the pipe axis.
• any labyrinth-like geometries can be selected that are suitable for the flowing Melt by constriction and / or deflection represent an obstacle at which the solidification can begin preferentially.
• the suction tubes 10, 1 1 made of copper or other material having a relation to the melt increased thermal conductivity.
• the suction tubes 10, 1 1 can be cooled prior to insertion into the mold. In general, it is achieved by the thermal properties of the suction tubes 10, 11 that the melt passing through the fiber preform 3 after complete infiltration preferably solidifies in the suction tube 10, 11 and clogs it.
• the casting mold is connected to a compressed air line through which after filling the mold with the light metal melt air is introduced under high pressure into the mold to significantly reduce the porosity of the solidified aluminum alloy and to give the piston 1 as a sufficient strength. Thereafter, both the individual fibers of Faserpreform 3 are firmly connected to the solidified light metal melt and the Faserpreform 3 in turn with the other areas of the piston 1.
• the final shape of the piston 1 is given to the piston blank by means of a machining process.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Chemical & Material Sciences (AREA)
• General Engineering & Computer Science (AREA)
• Combustion & Propulsion (AREA)
• Ceramic Engineering (AREA)
• Manufacture Of Alloys Or Alloy Compounds (AREA)

Applications Claiming Priority (2)

Publications (1)

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• 2013
  • 2013-12-19 DE DE102013226717.7A patent/DE102013226717A1/de not_active Withdrawn
• 2014
  • 2014-12-11 EP EP14824796.8A patent/EP3097299A1/de not_active Withdrawn
  • 2014-12-11 WO PCT/EP2014/077431 patent/WO2015091217A1/de active Application Filing
  • 2014-12-11 CN CN201480071465.4A patent/CN105849400A/zh active Pending
  • 2014-12-11 US US15/106,302 patent/US20170028464A1/en not_active Abandoned
  • 2014-12-11 JP JP2016540988A patent/JP2017500485A/ja active Pending

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