EP1293276A2 - Device for producing pressure cast metal parts with a core and an insert - Google Patents

Abstract

Device for producing a die cast part comprises an insertion part (4) and a removable core (6) forming an interlocking connection in covering regions. The insertion part supports the core. Bending moments acting on the core are transferred to the insertion part. An Independent claim is also included for a process for the production of a die cast part using the above device. Preferred Features: The insertion part and the core are connected outside of the die cast part by adhering, sintering or pressing the core onto the insertion part.

Description

The invention relates to a device for producing a Die casting component according to the preamble of claim 1 and a Method according to the preamble of claim 11.

Die casting is a cost effective method of manufacture of metallic components, in particular of light metal components. A principal disadvantage of die casting over others Casting process such as sand casting or chill casting consists in that undercuts with respect to the Entformungsrichtung of the component generally only by consuming and expensive slide can be realized.

US 4,446,906 proposes in this context, stable Lost cores, which preferably consist of salts together Insert with inserts in a die-casting tool. The example a cylinder crankcase, this method is explained. This is a salt core on cylinder liners, the with respect to the salt core have a spacer pushed. Thus, there is a between the core and the liner Gap filled by aluminum during die casting becomes.

A disadvantage of this arrangement is that as in the US 4,446,906 is shown in Figure 3, the core in essence free standing, what at the high pressures, the die-casting often leads to damage to the core and thus a high rejection rate.

Inserts are diecast, as well as in US 4,446,906 used as functional-acting areas that are locally specific Material properties such as high strength, better wear resistance, higher thermal conductivity or special have electrical properties. This is usually it necessary that the inserts partially on the surface lie open. Often the inserts are in the later component Due to the design, it is difficult to access.

By the hitherto known techniques, such. In the US 4,446,906 or by conventional sealing of the insert by pressing on tool contours are the Surface of the inserts not satisfactory before a Hintergießen the molten metal and in front of an associated To protect tinsel. Under baubles here is general solidified casting metal, usually in the form of thin platelets or perpendicular to the surface of an insert understood. The tinsel in turn leads to very expensive post-processing, the economic benefits of die casting to make a niece.

The object of the invention is, starting from said state of Technology, the damage of a casting core in the die-casting process reduce and a hicker-free outer contour of inserts to realize.

The object is achieved by a device with the characteristics of Claim 1 solved.

The device according to the invention comprises an insert part and a retrievable core used in a die casting tool are positioned. Since the insert partly in the Component is cast and partly a free surface , the core comprises the insert part by area, which referred to herein as coverage areas. In the coverage areas, the core and the insert are form-fitting connected.

The positive connection is designed so that they respect a casting metal is tight during die casting. This will avoid being on the core covered Surface of the insert a metal film, already mentioned Make baubles.

Furthermore, the connection is designed such that the insert supports the core. This means that bending moments during Die casting on the core act absorbed by the insert become. This is also due to the positive fit Connection of core and insert achieved. It should be remembered that that between core and insert quite locally Cavities may occur if thereby the mechanical Resilience of the core is not exceeded.

According to the invention, several compounds of insert and Core be positioned in a die-casting tool. An insert can be connected to multiple cores, as can one Core be associated with several inserts.

Diecasting will all be considered in the context of this invention Process understood in which under elevated pressure at least partially poured liquid casting metal in a permanent mold becomes. This includes die casting, the squeeze Casting, thixocasting, thixomolding or similar Method.

The connection of insert and core takes place in an advantageous manner Way outside of the casting tool. The connection is called a part positioned in the casting tool, reducing the cycle time is shortened and the positioning is simplified (claim 2).

To ensure a tight, positive connection it has proved to be useful, the core on the insert stick on or aufzusintern. Also has as expediently powder directly on the insert to the Core to compress (claim 3).

The casting tool may have recesses in which the connection Position defined positioned and preferred self centered (claim 4). Particularly preferred are the Core areas of the invention positioned in the recess, so that the insert into a mold cavity of the casting tool protrudes (claim 5).

Another advantage of the inventive device and the Association of insert and core is that the Core with respect to a Entformungsrichtung of the component undercuts can have. Undercuts are in many Cases structurally necessary, but only with expensive in die casting Slider technology to realize. By the invention Thus, the tool costs are reduced (claim 6).

To further reduce the bending moments on the core it is expedient, if the construction permits, the connection of insert and core obliquely to a main flow direction of the casting metal. An angle between 15 ° and 90 ° has proved to be advantageous (Claim 7).

In principle, the core can be made up of all substances that subsequently by dissolving in liquid and / or by mechanical Remove exposure. The core, however, must be the withstand mechanical stress that occurs during die casting. The core may be based on salt, e.g. For example, sodium chloride Consist and additives such as carbon and / or temperature resistant contain organic binders. Likewise, the core can be up the base of ceramic powders with appropriate binders consist. Salt and ceramic powders can be passed through water remove or wash out. Alternatively, the core may be up the basis of gypsum or cement, which are mechanically let remove (claim 8).

The casting metals used are preferably the metals customary in die-casting Aluminum, magnesium, zinc or alloys used therefrom (Claim 9).

The insert preferably has a melting temperature or a Decay temperature, which is higher than the temperature of the casting metal during casting. It is therefore possible For example, iron-based metals, copper-based, ceramics or metal-ceramic composites (claim 10).

Another component of the invention is a method for Production of a die-cast component according to claim 11 using A device according to any one of claims 1 to 10.

Preferred embodiments will be described with reference to FIGS to 3 shown. Further, in Examples 1 to 4 the inventive method for producing a die-cast component explained in more detail.

Fig. 1

ein Einlegeteil und einen Kern, positioniert in einem Gießwerkzeug, wobei das Einlegeteil von Gießmetall umgeben ist,

Fig. 2

ein Einlegeteil nach Fig. 1 mit Hohlräumen zwischen Kern und Einlegeteil,

Fig. 3

eine Verbindung von Einlegeteil und Kern und deren Positionierung in einem Gießwerkzeug.

Show it:

Fig. 1

an insert and a core positioned in a casting tool, the insert being surrounded by cast metal,

Fig. 2

an insert according to FIG. 1 with cavities between core and insert,

Fig. 3

a connection of insert and core and their positioning in a casting tool.

FIG. 1 shows a detail of a casting tool 2 in which a connection 3 of an insert 4 with a core 6 is arranged in a position-defined manner. The component thus produced is a housing for an electromagnet, the insert is the yoke for the electromagnet. The compound 3 is fixed by the core 6 in a recess 8. A casting metal 10 encloses the insert part and the core partially in the cast state.

The compound 3 is designed so that bending moments, the caused by a flow of the cast metal 10 on the core 6 be transferred to the mechanically stable insert 4 become.

According to the invention, it is important that the compound 3 between insert 4 and the core 6 with respect to the casting metal 10 is tight. Particularly high requirement is here in particular to the sealing edges 5 and to the immediately adjacent Set sealing surfaces 7. In the areas 7 is one possible large-area concern of the core 6 on the insert 4 required. This is also for the transmission of bending moments from the core 6 to the insert 4 required.

Other advantages of the arrangement are that through the Core 6 undercuts 12 can be imaged, what through a conventional die-casting process is not possible. Further can in the overlap area of the insert with the core Entformungsschrägen omitted on the insert or the insert can also have undercuts. Furthermore are the requirements for the tolerances of the insert less as with inserts without core environment, since the insert partially covered by the core.

As shown in Fig. 2 , in cavities 13 and 14 can be recessed in areas of the compound 3 ', where no attack of the cast metal 10, quite cavities. In the cavities 13 and 14 act on the core 6 'almost no bending moments, which is why in these areas no higher demands are placed on the nature of the core 6' and on the contact surfaces.

The core 6 or 6 'is as shown in FIGS. 1 and 2, centered in a conical recess 8. It is advantageous to sink the core in the depression, since he so is protected from a melt flow 18.

Another convenient protection of compound 3 before Melt flow 18 consists in an oblique arrangement of the compound 3 with respect to the main flow direction 16 of the cast metal 10, as shown in Fig. 3. Due to the oblique orientation the connection 3, the melt flow 18 according to the arrows 18th distracted. As a result, the force acting on the core 6 and reduces the resulting bending moments.

The oblique arrangement of the connection 3 with respect to the main flow direction 16 in the casting tool 2 is not for each component realizable. However, it may be possible for the gate 20 to arrange in the casting tool 2, that the advantageous Slope of the main flow direction is achieved. Furthermore it can be appropriate, not shown here shielding in To install casting tool 2, through which the melt diverted becomes.

The following will be advantageous with reference to three examples Embodiments of the method according to the invention described.

example 1

A salt core, consisting of sodium chloride and carbon becomes pressed into a green body and at a temperature of 700 ° C sintered. Its outer contours correspond after sintering those necessary for the connection with the insert part are, with a positive tolerance of at least 1/10 mm respectively. The salt core is at the contact surfaces with a Ceramic adhesive provided and pushed onto the insert. After curing of the ceramic adhesive are the contact surfaces close to a liquid casting metal. The connection is positioned analogously to Figures 1 to 3 in the casting mold. The casting tool is die-cast with aluminum filled. The aluminum solidifies into a component. The component is demoulded and deterred. Subsequently, the core becomes removed by a high pressure water jet.

Example 2

Analogously to Example 1, a salt core green body on the insert positioned. The tolerances of the green body amount also at least +0.1 mm. The salt core and the insert will be put together in a sintering furnace and analogous example 1 sintered. After the sintering process are the contact surfaces between the insert and the core also close to each other a liquid casting metal. The further procedure is analogous Example 1.

Example 3

An insert is positioned in a mold. The Press mold has the outer contours of the compound to be displayed on. A ceramic powder mixture based on titanium oxide, an organic binder based on polyethylene glycol containing, is filled in the mold, where it is the Einlegteil at least partially covered. Subsequently, the Powder with the insert pressed. The core and the insert are tightly connected at the contact surfaces. The further Method is analogous to Example 1.

Example 4

Analogous to Example 3, liquid slip is based on poured from plaster into the mold with the insert and cured. The further procedure is analogous to Example 1.

Claims (11)

Apparatus for producing a die cast component, comprising a die casting tool with at least one insert and at least one subsequently removable core,
characterized in that the at least one insert part and at least one core form a positive connection in covering areas, the connection of the insert and the core to a pressurized cast metal is dense, the insert supports the core, wherein Bending moments that act on the core, are transferable to the insert. Device according to claim 1,
characterized in that a connection of the insert and the core takes place outside of a die. Apparatus according to claim 1 or 2,
characterized in that the connection of the insert and the core by gluing, sintering or pressing the core takes place on the insert. Device according to one of claims 1 to 3,
characterized in that the connection is positioned defined in a recess of the die casting tool. Device according to claim 4,
characterized in that core portions of the connection are positioned in the recess. Device according to one of claims 1 to 5,
characterized in that the core regions of the connection with respect to a Entformungsrichtung of the component have undercuts. Device according to one of claims 1 to 6,
characterized in that the connection is arranged with respect to a main direction of flow of the casting metal at an angle between 15 ° and 90 °. Device according to one of the preceding claims,
characterized in that the core comprises as essential ingredient salt and / or other inorganic, powdery materials. Device according to one of the preceding claims,
characterized in that the metal component consists of aluminum, magnesium, zinc or alloys of these metals. Device according to one of the preceding claims,
characterized in that the melting temperature and / or the decomposition temperature of the insert is above a casting temperature of the cast metal. Method for producing a die-cast component using a device according to one of claims 1 to 10,
characterized, that an insert with a subsequently removable core by bonding and / or sintering and / or pressing and / or Aufschlickern with respect to a casting metal is firmly connected to a compound, the connection is placed in a diecasting tool, the die cast component is poured off by die casting, the component is demoulded and the core is removed by a solvent and / or by mechanical working.

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