EP2812136B1 - Casting method - Google Patents

Description

The invention relates to a casting method with a lost casting mold or a partially lost casting mold, in which at least one pourable component is arranged in the casting mold, wetted with size and at least partially enclosed by the casting material.

In foundry technology, pourable components are needed to make cavities or to fix the cavity forming bodies. For this purpose, so-called lost casting molds are preferably used, which are formed from molding sand or core sand and are destroyed after a single casting process during the demolding of the molded molded element. The cavities within such a mold are created by introducing into the mold cores made, for example, made of core sand, in particular shot. These cores are held in the mold by pourable components, inter alia in the defined position. The pourable components can be placed between two cores, between a core and the mold, or between other elements in the mold.

Numerous pourable components, such as core clips, core supports, cooling sleeves, heat sinks and / or tube elements or sections are known in the prior art, which are arranged in a mold and enclosed by the casting material and form such a material connection. In particular core clips serve to counteract deformations of cores, which are preferably hollow, and to allow a uniform wall thickness of the casting in each direction.

The DE 20 2012 009 504 U1 describes, for example, a two-part core support with profiles that serve to keep the water jacket cores for the future cooling water space exactly at a distance when casting an engine block made of cast iron or nodular cast iron (GG, GGG, GGV). The core clips remain in the water jacket after casting.

After the casting mold has been produced, an insertable component can be inserted into the casting mold. Subsequently, the mold is preferably blown with a stream of compressed air to remove loose molding sand, which would reduce the quality of the molding element to be cast, from the mold.

After blowing so-called sizing is applied to a surface of the mold, wherein such an order takes place by means of an injection or dipping process. Subsequently, the size is dried, for example in a chamber furnace or continuous furnace at temperatures of 150 to 200 ° C. After that, the actual casting process can begin.

Conventionally, a pourable component, such as a core clasp, be arranged only after blowing and after an order of the size in the mold, as adhering molding sand and / or adhering to the pourable component sizing the formation of a material connection between the pourable component and the casting ver - or at least obstruct.

From the DE 20 2011 051 410 U1 It is therefore known that at least in sections a coating agent is applied to the surface of the pourable component, wherein the coating agent forms a separation-active surface, which prevents adhesion of molding sand and sizing to the pourable component.

The object of the invention is to provide a method in which, even without coating agent, the pourable component can be inserted into the same prior to the application of the size to the surface of the lost casting mold.

This object is achieved in that after the application of the size, the pourable component is cleaned.

As a result, the pourable component can be used immediately after production of the casting mold. The sizing is then applied to the surface of the lost mold and then the sizing is removed from the pourable component before undergoing the drying operation along with the cores. Subsequently, the casting process.

The advantage of the invention consists essentially in a lighter automation and in that the casting produced by the process according to the invention has a better surface quality.

A preferred embodiment of the method according to the invention is that the pourable component is cleaned by blowing with a fluid.

It has been found within the scope of the invention that by blowing with a fluid, the sizing can be easily and quickly removed from the pourable component. The process is easy to automate and a better surface quality is achieved.

It is part of the invention that the fluid is water or a gaseous medium, in particular nitrogen or compressed air.

Compressed air is preferred among these fluids because it is usually available in foundries.

It is part of the invention that the fluid is passed through a pressure reducer and connected thereto tubes to the pourable component.

According to the invention it is provided that are used as einießbare components core clips, core supports, cooling sleeves, heat sink or pipe elements or sections. These can consist of any materials and have any geometry.

In the context of the invention is also a casting, which is prepared according to the inventive method.

An embodiment of the invention will be explained in more detail with reference to drawings.

Fig. 1

einen Sandkern für einen Wassermantel mit einer Kernspange,

Fig. 2

das gesamte Sandkernpaket, bestehend aus mehreren Sandkernen, als Explosionszeichnung,

Fig. 3

das gesamte Sandkernpaket im zusammengebauten Zustand,

Fig. 4

das Entfernen der Schlichte im Bereich der Kernspange.

Show it

Fig. 1

a sand core for a water jacket with a core clasp,

Fig. 2

the entire sand core package, consisting of several sand cores, as an exploded view,

Fig. 3

the entire sand core package in the assembled state,

Fig. 4

the removal of the size in the area of the core clip.

A mold for an engine block is made of molding sand. The later cooling water space and other cavities are filled by sand cores (1), wherein the cores forming the cooling water space, referred to as water jacket cores (1). In order to keep the cores (1) exactly at a distance, pourable components (2), for example, core supports or core braces are set corresponding to the required Gußwandstärke the cores (1) and the shape or the cores (1) relative to each other or each Hold the core (1) in place and remain in the casting after casting. The pourable components (2) consist for example of carbon steel with a carbon content of about 0.1%, which is protected by a coating with tin or copper from corrosion, or stainless steel. These steels are equally suitable for gray and cast steel. The melting point of the steel used is higher than the melting point of the casting material. Properly sized pourable components (2) should form a material connection with the cast iron, in particular welding. Fig. 1 shows a sand core (1) for a water jacket with a core clip (2).

Fig. 2 shows the entire sand core package, consisting of several sand cores (1), as an exploded view and Fig. 3 the entire sand core package in the assembled state.

Now, the lost mold is blown out by means of a compressed air flow to remove loose molding sand, which would reduce the quality of the molding element to be cast, from the mold.

Sizing is then applied to the surface of the lost mold. As a rule, water-based or organic solvent-based sizing agents are composed. To apply the sizing, for example, the entire lost Mold are dipped by means of a robot in a sizing bath and then moved to wet the entire surface with sizing.

In the next step ( Fig. 4 ), the sizing of the pourable component, here the core clasp (2) is removed. To a compressed air connection, a pressure reducer is connected, via which the compressed air is passed through one or more tubes (3) to the pourable component (2). By the compressed air emerging from the tube or tubes (3), the sizing is removed from the pourable component (2) or the pourable components (2).

Subsequently, the size is dried, for example in a chamber furnace or continuous furnace at temperatures of 150 to 200 ° C.

Thereafter, the actual casting process can be carried out, in which the liquid casting material, such as gray cast iron or cast steel (or other casting material, such as copper or aluminum) is filled into the lost mold. The pourable component (2) is melted at least superficially during the casting process and thus forms a cohesive connection with the molding element to be cast. When filling the mold, the surface of the pourable component (2) is heated rapidly to near the temperature of the melt and enriched by diffusion with the carbon of the cast iron. As a result, the melting temperature of the surface of the pourable component (2) is reduced locally, causing it to melt.

Claims (5)

1. Casting method using an expendable or partially expendable casting mould, in which method at least one embeddable component (2) is positioned in the mould, wetted with wash and surrounded at least partially with casting material, characterised in that the embeddable component (2) is cleaned following application of the wash.
2. Casting method according to claim 1, characterised in that the embeddable component (2) is cleaned by blowing a fluid onto it.
3. Casting method according to claim 2, characterised in that the fluid is water or a gaseous medium, in particular nitrogen or compressed air.
4. Casting method according to either of claims 2 or 3, characterised in that the fluid is conveyed to the embeddable component (2) via a pressure reducer and tubes (3) connected thereto.
5. Casting method according to any one of the claims 1 to 4, characterised in that core clasps, chaplets, cooling sleeves, chills, pipe elements or pipe sections are used as embeddable components (2).

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