DE102020004163A1 - Process for the production and use of casting cores for all casting processes, in particular die casting, as well as casting cores produced using this process and intended for the creation of defined cavities in cast parts - Google Patents

Abstract

In foundry technology, sand cores, some with core cores, are produced, which are used to depict cavities in cast parts. Long, thin, curved bores with a small cross-sectional area in cast parts often cannot be produced with cores, since the positioning of core cores in green sand cores in the conventional production is not sufficiently precise and cores without cores cannot withstand the stresses that occur during handling and casting. The new cores can withstand significantly greater loads and pressures and is coated on the inside with a sizing and filled with one or more molding materials (2) (core sand or powder or other granules) and a spiral (3), it also allows long and curved cavities with a small cross-sectional area in castings without subsequent The helix embedded in the molding material, whose pitch s is adjusted with the compression of the molding material, can be used to advantage for removing the molding material. These cores are used to produce straight or curved, in particular long cavities with any desired, but in particular circular and constant cross-section and in particular a large ratio of length to cross-section. The core shell (1) remains in the component after the casting process.

Description

field of use

The invention relates to casting cores or cored wires, tubular wires and core bearings for cored and tubular wires and production methods for the cored wires, tubular wires and core bearings for cored and tubular wires and methods for their use for the production of cavities in castings according to the preamble of claim 1 and the following Claims 2-10.

State of the art

It is known that metal tubes filled with mineral powders, which are drawn into wires, are used in foundry technology as seed wires and in welding technology as filler materials of the same or dissimilar type called cored and folded wires, cf. DE 197 12 817 C2 and DE 41 04 562 A1 .

In foundry technology, sand cores are also produced, some with core cores, which are used to reproduce cavities in cast parts.

Core cores serve to stabilize the cores under mechanical stress.

Long, thin, curved channels with a small cross-sectional area in castings often cannot be produced by cores and must be subsequently produced by machining (drilling), since the positioning of core cores in green sand cores is not sufficiently precise in conventional production (e.g. in the result of welding with melt) and coreless cores cannot withstand the (in particular mechanical and thermal) loads that occur during handling and casting.

With the DE 100 26 546 stable cores are described, with which long curved channels with a constant cross-section are modeled in castings.

In the DE 10 2008 039 208 resistant cores are described which contain mechanical shaping aids which are introduced into the core cladding in a predefined shape.

Disadvantage of the prior art

Long, thin, curved channels with a small cross-sectional area often cannot be produced by cores in castings and must subsequently be produced as bores by machining, since the positioning of core cores in green sand cores is not sufficiently precise in conventional production (e.g. in the sequel Welding with melt) and coreless cores do not withstand the (particularly mechanical and thermal) loads that occur during handling and casting.

cores according to DE 100 26 546 solve the stability problems reliably.

In some cases, the shaping of the molding material with high or low pressure water jets, compressed air jets or vibration technology takes a relatively long time, so that a reduction in the shaping time is particularly desirable for these applications.

cores according to the DE 10 2008 039 208 are characterized in particular by a cross-section that is not constant over the length.

Forming aids used there, including coils, are introduced into the respective core in their final position with respect to their center line along their cross section.

object of the invention

The object of the invention is, in particular, to produce and use long cores with a small cross-sectional area that can withstand the (in particular mechanical and thermal) loads that occur, and the production of straight or curved, in particular long, cavities of any cross-sectional shape in castings with as little subsequent machining as possible Allow for processing and faster removal of the mold material.

solution of the task

The task is solved with a further development of the DE 100 26 546 , So with cores that are produced by the method of claims 1 to 10 and used in methods with features of claims 1 to 10.

Partial tasks are solved by cores and methods of the following claims 2 to 10.

The metal jacket (1) of the casting core withstands the loads that occur and allows bending and twisting as well as flat areas of the cavity to be formed from a straight cored wire.

The molding material (2) and the coil (3) embedded therein with the initial _{pitch s 0} and the other parameters coil diameter D _w , _{coil wire diameter D d} and coil outer diameter messer D _wa are inserted into the core shroud on the same system.

_{The molding material (e.g. core sand or core powder or granules) is solidified to the final dimension of the inside diameter (D k} ) during diameter-reducing forming (drawing, rotary swaging or similar) of the cored wire and is possibly covered by the inside coating of the metal pipe with Sizing material protected from direct contact with melt.

The pitch of the helix (3) is changed from the initial pitch s ₀ to the helix pitch s when the flux-cored wire is formed. The following applies: s ₀ ≥ D _d and s < 5x D _d

After using the casting core in a casting process such. B. die casting, sand casting or chill casting, the mold material must be removed from the cavity in the metal casting.

In the case of the cores according to the invention, this is done by exposing a piece of helix (3) in a suitable manner at one or both ends of the respective core.

This exposed end of the coil is grabbed and pulled out.

In order to compensate for alloy differences between the melt and the metal shell of the core, which may melt or melt away, the metal shell (1) can be coated with (mineral) alloying aids (5).

Core supports (6a, 6b) and core bearings ((6a, 6b, also called core marks), spacers or fixing elements (6a, 6b) can advantageously be attached to the metal jacket (1) of the core, e.g. by welding or mechanical joining .

If necessary, the core ends can be closed by plugs (6a, 6b), caps (6a, 6b) or other suitable closures.

Advantages of the Invention

The invention makes it possible to produce straight or curved cavities, in particular channels (bores) with a small cross-sectional area and great length, by primary shaping. Furthermore, non-soluble molding materials are also formed quickly and reliably, and subsequent machining can largely be dispensed with.

Sample description of the patent application

• 1: Gießkern, bestehend aus einem geschlossenen Metallmantel (1) und gefüllt mit einem Formstoff (2), wie z. B. Kernsand oder -pulver, -granulat oder einem oder mehreren anderen Mineralen bzw. Mineralstoffgemischen, und einer darin eingebetteten Wendel (3) mit der Steigung s.
• 2: Gießkern, bestehend aus einem geschlossenen Metallmantel (1), Innenfläche mit einer ersten Mineralschicht (4), z. B. einer Trenn- bzw. Schlichteschicht, beschichtet und zusätzlich gefüllt mit Formstoff (2), wie Kernsand, -pulver, -granulat oder einem anderen Formstoff, sowie einer darin eingebetteten Wendel (3).
• 3: Gießkern, bestehend aus einem geschlossenen Metallmantel (1), Außenfläche mit Metallurgiehilfsstoff (5) beschichtet, Innenfläche mit einer Trenn- bzw. Schlichteschicht (4) beschichtet und gefüllt mit Formstoff (2), wie z. B. Kernsand, -pulver, -granulat, sowie einer darin eingebetteten Wendel (3).
• 4: Gießkern, bestehend aus einem geschlossenen Metallmantel (1), Außenfläche mit Metallurgiehilfsstoff (5) beschichtet und gefüllt mit Formstoff (2) wie z. B. Kernsand, -pulver oder einem anderen Füllmaterial, sowie in diesen Formstoff eingebettete Wendel (3).
• 5: Gießkern, bestehend aus einem geschlossenen Metallmantel (1), Innenfläche mit einer ersten Mineralschicht (4), z. B. einer Trenn- bzw. Schlichteschicht, beschichtet und zusätzlich gefüllt mit Formstoff (2), wie Kernsand, -pulver, -granulat oder einem anderen Formstoff, sowie einer darin eingebetteten Wendel (3) und die Enden jeweils mit einer hohlen Kernstütze (6a) sowie einer geschlossenen Kernstütze (6b) versehen.

Embodiments of the invention are in the drawings 1 until 5 shown and described in more detail below:

• 1 : Casting core, consisting of a closed metal jacket (1) and filled with a molding material (2), such as. B. core sand or powder, granules or one or more other minerals or mineral mixtures, and embedded therein helix (3) with the pitch s.
• 2 : casting core consisting of a closed metal jacket (1), inner surface with a first mineral layer (4), e.g. B. a separating or sizing layer, coated and additionally filled with molding material (2), such as core sand, powder, granules or another molding material, and a helix (3) embedded therein.
• 3 : Casting core, consisting of a closed metal shell (1), outer surface coated with metallurgy additive (5), inner surface coated with a separating or sizing layer (4) and filled with molding material (2), such as e.g. B. core sand, powder, granules, as well as a coil (3) embedded therein.
• 4 : Casting core, consisting of a closed metal jacket (1), outer surface coated with metallurgy additive (5) and filled with molding material (2) such as e.g. B. core sand, powder or other filling material, as well as embedded helix (3) in this molding material.
• 5 : casting core consisting of a closed metal jacket (1), inner surface with a first mineral layer (4), e.g. B. a separating or sizing layer, coated and additionally filled with molding material (2), such as core sand, powder, granules or another molding material, and a helix (3) embedded therein and the ends each with a hollow core support (6a ) and a closed core support (6b).

Molding materials such as core sand, powder or granules are chemically identical substances.

The grain size of the molding materials is adjusted to the processing parameters of the core manufacturing process.

In the simplest version, a molding material (2) such. B. core sand without binder and a coil (3) with the coil initial pitch s ₀ filled into a metal tube, which is then reduced in one or more forming steps to the final metal tube diameter D _m.

The helix pitch s and the diameter D _{k of} the subsequent cavity are assigned to this D _{m .}

The omission of binders is intended to enable several passes with intermediate annealing (WBH) that may be necessary.

When reducing the diameter of the metal shell, the filling is usually sufficiently compacted.

Depending on the casting process, the diameter-reducing forming process can also be dispensed with.

During the forming of the cored wires, the filling prevents unwanted deformation of the metal tube.

In the case of loose, non-solid filling material, the ends of the metal jacket are closed by plugs (6a, 6b), caps (6a, 6b) or other closures (6a, 6b), which are also known as so-called core marks (6a, 6b) or core bearings (6a, 6b) can be used in the form.

A malleable alloy of the same or dissimilar type, matched to the intended melt, is selected as the metal for the tube material.

A metal wire with sufficient strength is to be provided as the material for the coil.

Depending on the melting point of the core cladding alloy and the temperature of the melt, the core cladding is either not melted, partially melted, or completely melted when the mold is filled.

If the core shroud does not melt, there is the greatest risk that casting defects will occur in the melt due to the cooling effect of the core shroud.

This can be counteracted, for example, by resistance heating, induction heating or other electrical or magnetic heating of the core.

When the core shroud melts, there is a risk of mineralization forming when the melt comes into contact with the mold material.

To avoid this problem are in the 2 and 3 Modified cores are described in which the melt is separated from the mold material (e.g. core sand or core powder) by a separating or sizing layer (4).

When the core cladding melts, if the melt and core cladding are made of different alloys, the composition of the melt is locally changed by mixing the melt with the cladding material.

To influence the metallurgical composition in this area, the metal jackets (1) of the cores in the 3 and 4 surrounded by a metallurgy auxiliary jacket (5). Appropriate risers are to be provided in the mold for the removal of any floating slag that may occur.

Reference List

1

metal jacket

2

mold or filler

3

helix

4

Sizing or separating layer

5

Metallurgy Auxiliary Coat

6a

exemplary core brand or core support hollow

6b

exemplary core brand or core support solid

Dm

Metal pipe final diameter (outer diameter)

dk

Inner end diameter of the metal tube and the cavity to be created

s0

Helix initial pitch at the start of core production

s

helix pitch

Dw

coil diameter

Dwa

Helix Outer Diameter

Dwi

Inner coil diameter

Dw

Inner coil diameter

dd

Spiral profile wire diameter

QUOTES INCLUDED IN DESCRIPTION

This list of the documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 19712817 C2 [0002]
• DE 4104562 A1 [0002]
• DE 10026546 [0006, 0009, 0014]
• DE 102008039208 [0007, 0011]

Claims (10)

Process for the production of a core as well as a core produced thereafter for the production of straight or curved cavities with a large ratio of length to cross-sectional area of any contour in cast parts with a core jacket (1) of the same type or of a different type compared to the melt, which is suitable for casting, partial or complete melting in the Melt is used, and a filling in the core jacket (1), consisting of natural or synthetic molding material (2), such as in particular core sand, core powder or other suitable moldable mineral or metallic granules with or without binders and a helix (3) with helix pitch s produced during the forming production of the diameter D _m as well as a method for using this core in a casting process for the production and core removal of a cast part by pulling the helix out of the cast part after casting and thus dissolving the mold material. Process for the production of a core and a core produced thereafter claim 1 characterized in that the metal jacket is covered with a metallurgical auxiliary material jacket which is melted in the melt. Process for the production and use of a core and core produced thereafter claim 1 with a metal jacket of the same or different type compared to the melt, which is used for partial melting in the melt. Core according to any of the preceding Claims 1 until 3 , characterized in that it is provided with an additional sizing layer or separating layer between the metal jacket and the filling made of molded material and, if necessary, a helix. A method for producing a core and a core produced therefrom according to one of the preceding claims, characterized in that the helix and molding material are introduced into the metal tube eccentrically or concentrically or a combination of both using the same system. Process for the production of a core and a core produced according to one of the preceding claims, characterized in that the core ends are closed with plugs (6a, 6b), caps (6a, 6b), truncated cones/pyramids (6a, 6b) or the like, so that the filling embedded in the metal shell can be held and/or the core can be stored in the mould. Process for producing a core and core produced therefrom according to one of the preceding claims, characterized in that core supports (6a, 6b), core bearings (6a, 6b), spacers or fixing elements (6a, 6b) are attached to the core jacket. Process for producing cavities in castings using cores according to one of the preceding claims, characterized in that the core in the casting mold is optionally heated in an electrical circuit as a resistance or by induction to the desired operating temperature during casting. Process for the production and use of a core and a core produced therefrom according to one of the preceding claims, characterized in that the filament ends are exposed after casting by detaching, in particular breaking off, a short piece of the jacket region or a jacket sleeve. Filled metal element for mapping cavities in components that are manufactured by die casting.

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