Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22C—FOUNDRY MOULDING
  • B22C7/00—Patterns; Manufacture thereof so far as not provided for in other classes
  • B22C7/06—Core boxes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22C—FOUNDRY MOULDING
  • B22C21/00—Flasks; Accessories therefor
  • B22C21/12—Accessories
  • B22C21/14—Accessories for reinforcing or securing moulding materials or cores, e.g. gaggers, chaplets, pins, bars
• • 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
  • B22C9/106—Vented or reinforced cores
• • 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
• • 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
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D29/00—Removing castings from moulds, not restricted to casting processes covered by a single main group; Removing cores; Handling ingots
  • B22D29/001—Removing cores
• • 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
• • 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

Definitions

• the present disclosure relates to a method of manufacturing a hollow metal part by casting and, more particularly, by die casting.
• Such a method is particularly useful for the manufacture of parts which have an internal recess and which, therefore, are not demoldable directly, such as, for example, a fluid circulation duct or a semi-closed container (eg a casing ).
• the foundry includes processes for forming metals (i.e. pure metals and alloys) which consist of casting a liquid metal in a mold to produce, after cooling, a given piece, limiting as much as possible the subsequent work of finishing on this piece.
• metals i.e. pure metals and alloys
• the liquid metal is injected into the mold under a significant injection pressure, typically between 100 and 1200 bar (i.e. 10 and 120 MPa).
• the injection speed in the mold is typically between 10 m / s and 80 m / s and the temperature of the liquid metal is typically between 400 and 980 ° C.
• pressure molding is often reserved for large-scale production for markets such as automotive or household appliances, because of the high price of tools (molds and cutting tools).
• the smelter molds two half-parts which are then assembled mechanically by welding or gluing.
• This solution is not satisfactory because, on the one hand, it requires two molding tools (one for each half-part) and, on the other hand, the step assembly is delicate because of the required sealing at the assembly area.
• the present disclosure relates to a method of manufacturing a hollow metal piece, by casting, in which:
• a destructible core comprising a body made of aggregated compounds, and a shell which surrounds and adheres to the body;
• the kernel is arranged in a mold
• the body of the core is disintegrated and evacuated via discharge orifices formed in the carapace and in the part;
• the carapace is destroyed and evacuated via evacuation orifices formed in the room.
• the core used here differs from conventional cores used in gravity foundry, in particular by the fact that it has a shell enabling it to mechanically resist the stresses exerted by the liquid metal during the injection. Without this shell, the core would disintegrate under these constraints.
• the shell adheres to the body of the core to avoid a separation of the shell and the body during injection, and as the shell rests on the body, the latter takes some of the constraints during injection.
• Such a manufacturing method is particularly interesting in die casting because the stresses exerted by the liquid metal during the injection are high and the carapace of the core is then of interest.
• the mechanical strength of the shell is sufficient to resist the under-pressure injection of the liquid metal and, during molding, the liquid metal is injected under pressure into the mold, around the core.
• this manufacturing process could be used in foundry in other applications such as low-pressure molding or gravity casting (eg for ferrous alloys and non-ferrous alloys, in metal or non-metallic molds)
• the choice of the constituent material of the shell is made according to the good mechanical strength of this material, and its good adhesion to the core. Examples of materials are given below, but a person skilled in the art could easily, in view of this disclosure, consider others.
• the material constituting the shell also has one or more of the following properties:
• the carapace of the core is made, for example, based on particles aggregated by a binder (s) of organic nature (eg polyurethane), mineral (eg silicate, colloidal silica, ethyl silicate, low-point metals). fusion) or hydraulic (eg plaster, cement, lime).
• a binder eg polyurethane
• mineral eg silicate, colloidal silica, ethyl silicate, low-point metals.
• fusion eg plaster, cement, lime
• the particles may be ceramic, calcined clay, with or without zircon. They can result from the recycling of an old carapace.
• the shell is metallic.
• the core body is, for example, foundry sand or cast plaster, possibly loaded with fibers.
• the binder used to aggregate the core compounds may be hydraulic, organic (eg cellulose) or inorganic (eg silicate).
• the filler fibers may be organic or mineral in nature (eg linen, wood, glass).
• the destructible core further includes a skeleton that traverses the core body and is attached to the shell.
• This framework can be destroyed and evacuated at the same time as the body and / or the carapace. Such a framework makes it possible to further strengthen the mechanical strength of the core.
• the core body is made by aggregating compounds in a box provided with pins that pass through the inside of the box, so that the body, once removed from the box, presents recesses in place of the pins, and filling these recesses with a material constituting the framework, for example by dipping the body of the core in a slip, injecting (under low pressure) this slip or by gravity flow the slip in a container.
• the recesses and corresponding framing members may pass right through, or only partially, the core body.
• the core body is dipped one or more times in one or more slips, so as to cover the body with one or more layers of curable material.
• a slip plaster can be used.
• the core body may be first dipped in a first slip to form the optional backbone and the lower layer of the carapace, and then in other slip to form the upper layer or layers of the carapace .
• the core body can be dipped in a first slip to form the framework and a lower layer of the shell and then in one or several other slips to form one or more upper layers of the shell. Instead of soaking, it is possible to make the shell by injection of the slip.
• the constituent materials of the shell and the framework may be identical or different.
• the criteria used for the materials of the shell and the frame do not necessarily correspond.
• the framework does not come into contact with the injected metal, its chemical passivity vis-à-vis this metal is not a selection criterion.
• the mechanical strength of the framework may be lower than that of the shell.
• the framework is made of aggregated, disaggregated compounds. Thus, one can disaggregate and evacuate the body and the frame, in one operation, according to a method of débourrage.
• the body of the nucleus is made by aggregation of compounds in a box provided with support members which traverse (partially or partially) the inside of the box, and
• the shell is made around the body and the support members so that the support members pass through the shell.
• the support members are then used to hold the core in position in the mold during injection. Depending on the position occupied by the support members in the core, these can also serve to enhance the strength of the core.
• the support members are hollow and define exhaust passages for gases that are formed by thermal decomposition of certain core components during molding of the workpiece. This makes it possible to limit the risks of deformation related to these gases, especially when the part has thin walls.
• the support members are extracted the piece to provide the evacuation ports through which the body of the core and / or the shell are evacuated.
• FIG 1 shows a box for the manufacture of the body of a core.
• FIG 2 is a side view of the core body made with the box of FIG 1.
• FIG 3 is a perspective view of the core made with the body of FIG 2.
• FIG 4 is a sectional view of a mold in which is disposed the core of FIG 3.
• FIG 5 is a perspective view of a hollow metal piece obtained by casting in the mold of FIG 4.
• FIG 1 shows a box 10 for the manufacture of the body 22 of a core 20.
• This box comprises two half-shells 10A, 10B which, once assembled, define between them a free space 12 intended to receive the compounds which will form the core body.
• pins 16 Inside the box, ie in the free space 12, extend pins 16.
• these pins 16 pass through the free space 12 from one end to the other, each pin 16 being formed of two half 16A, 16B carried, respectively, by the two half-shells 10A, 10B, and located in the extension of one another, once the half-shells assembled.
• each member 18 is traversed by an inner passage (a lumen) opening at both ends of the organ.
• the free space 12 is filled with aggregatable compounds, for example sand grains, mixed with at least one curable resin.
• aggregatable compounds for example sand grains
• the resin (s) have hardened (eg by heating, or using a catalyst gas)
• the sand grains are aggregated and form the body 22.
• the body 22 is then extracted from the mold 10 .
• the body 22 has recesses
• the body 22 is immersed one or more times in one or more fluid paste baths, or slips, so as to cover the body with one or more layers of a hardenable material.
• the hollow support members 18 are used. Typically, pins are passed inside the members 18, which allows the body 22 to be held and to plug the internal passage of the organs 18 to prevent them from filling up.
• the deposited layer is cured, for example in air.
• the recesses 26 of the body 22 fill to form a framework 36.
• the framework 36 is thus composed of several elements which pass through the body 22 of the core and are connected to the shell 40.
• the frame members pass right through the body, so that the two ends of each frame member are connected to the shell 40.
• the first slip also forms the first or lower layer of the shell 40.
• Other layers, if any, of the shell 40 may be obtained by dipping the body 22 in other baths of hardenable material.
• FIG 3 shows the core 20 obtained after formation of the shell 40 around the body 22.
• the core 20 it is possible to manufacture the core 20 from the following materials and under the following conditions: to manufacture the body 22, use is made of foundry sand pre-coated with resin and hardener and the resin is cured with its hardener.
• the sand used is 55 finite silica AFS. The fineness of the sand can change depending on the shape and size of the core to be made.
• the resulting body 22 is immersed in a refractory slip mixed with colloidal silica. During the first soaking the recesses 26 are filled with slip to make the frame. The body 22 is dried and returned to the slip as many times as necessary to obtain the desired shell thickness 40 after the last drying.
• the core 20 is placed in the cavity 51 of a mold 50, as shown in FIG. 4.
• This figure shows the mold 50 and the core 20 in section.
• the core 20 is held in position in the mold 50 by means of hollow pins 53, integral with a portion of the mold 50, and driven into the support members 18 of the core 20.
• the liquid metal is melted and injected into the mold, around the core 20.
• the injection of the metal can be under-pressure, the shell 40 resistant to the stresses exerted during the injection and allowing the core 20 to maintain its integrity.
• gases related to the thermal decomposition of certain elements (typically binders) constituents of the core 20 are advantageously discharged outside the mold 50, via the internal passages of the support members 18 and the pins 53. This evacuation is symbolized by the arrows G in FIG 4.
• a metal part 60 which surrounds the core 20, the core 20 materializing a hollow space inside this part.
• the core 20 is subjected to a conventional deburring process, typically mechanical and / or hydraulic.
• the body 22 of the core then disintegrates under the combined effect of the thermal decomposition of the binders which constituted it (this decomposition taking place during the injection of the liquid metal, under the effect of the temperature of this metal) and the stresses breaking. If its composition allows it, the framework 36 can be disintegrated at the same time as the body 22. Otherwise, the frame 36 can be extracted after the body 22, for example, by subjecting the piece to a second method of breaking in.
• the elements resulting from the disintegration of the body 22 and, possibly, the framework 36, are discharged through the end orifices 62 of the hollow tubular piece 60.
• the support members 18 are extracted at the same time as the body 22 through these orifices 62. Note that these orifices 62 pass through the part 60 and the shell 40.
• the discharge orifices are formed by extracting the support members 18 from the core 20.
• the hollow tubular metal part 60 illustrated in FIG. 5 is thus obtained, the internal face of this part 60 being covered by the shell 40.
• the shell 40 is then destroyed and discharged through the orifices 62 to obtain the piece 60 alone.
• the shell 40 is destroyed by shot blasting or by peeling under water pressure (5 to 50 MPa) depending on the strength of the part 60.
• the piece 60 by conventional pressure molding of an aluminum-silicon-copper alloy.
• the injection pressure can vary from 100 bars to 1200 bars (ie 10 and 120 MPa), the flow rate of the metal can vary from 10 to 80 m / s.
• the silicon content can vary from 2 to 20%, the copper content can vary from 0.1 to 10%.
• the alloy Al Si 9 Cu 3 (Fe) can be used.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Molds, Cores, And Manufacturing Methods Thereof (AREA)
• Mold Materials And Core Materials (AREA)
• Casting Devices For Molds (AREA)
• Moulds For Moulding Plastics Or The Like (AREA)
• Manufacture Of Alloys Or Alloy Compounds (AREA)

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

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• 2012
  • 2012-04-16 FR FR1253486A patent/FR2989293B1/fr active Active
• 2013
  • 2013-04-11 CN CN201380020368.8A patent/CN104302422B/zh not_active Expired - Fee Related
  • 2013-04-11 EP EP13719995.6A patent/EP2838679A2/fr not_active Withdrawn
  • 2013-04-11 CA CA2870546A patent/CA2870546A1/en not_active Abandoned
  • 2013-04-11 US US14/394,715 patent/US9452469B2/en not_active Expired - Fee Related
  • 2013-04-11 BR BR112014025731A patent/BR112014025731A2/pt active Search and Examination
  • 2013-04-11 WO PCT/FR2013/050792 patent/WO2013156713A2/fr active Application Filing
  • 2013-04-11 KR KR1020147032147A patent/KR20140147893A/ko not_active Application Discontinuation
  • 2013-04-11 JP JP2015506283A patent/JP6277178B2/ja not_active Expired - Fee Related
  • 2013-04-11 IN IN9024DEN2014 patent/IN2014DN09024A/en unknown
  • 2013-04-11 RU RU2014145837A patent/RU2635596C2/ru not_active IP Right Cessation
  • 2013-04-11 MX MX2014012537A patent/MX357506B/es active IP Right Grant

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