EP2352608A1

EP2352608A1 - Method and device for casting a cast part from a metal melt

Info

Publication number: EP2352608A1
Application number: EP09759721A
Authority: EP
Inventors: Herbert Smetan; Klaus Lellig
Original assignee: Nemak Dillingen GmbH
Current assignee: Nemak Dillingen GmbH
Priority date: 2008-11-24
Filing date: 2009-11-23
Publication date: 2011-08-10
Anticipated expiration: 2029-11-23
Also published as: UA101526C2; JP5481488B2; JP2012509767A; RU2480309C2; MX2011005066A; CN102223969B; MX340704B; EP2352608B1; KR101247361B1; BRPI0921178B1; US20120012272A1; BRPI0921178A2; CN102223969A; PL2352608T3; CA2742889C; WO2010058003A1; US8302659B2; KR20110099114A; CA2742889A1; ES2436315T3

Abstract

The invention relates to a method and a device for casting a cast part G from a metal melt M. During the method according to the invention, a casting mold F comprising a mold cavity H that shapes the cast part G, a feed system 10 and a pouring channel 13, said casting mold being mounted in a bogie, is rotated to a fill position and filled with a metal melt. As a consequence of the effect of gravity, the melt flows through the pouring channel, wherein the main flow direction of the melt makes an angle relative to the acting direction of the force of gravity. The filling is continued until the casting mold F and the pouring channel 13 are completely filled with metal melt M. Then, the casting mold F is sealed by a stopper 18 placed in the fill opening 14 of the pour channel 13, and is rotated to a solidification position in which the melt M present in the feed system 10 is pushed against the melt M present in the mold cavity H. The casting mold G is held in the solidification position until the metal melt M present in the casting mold F has reached a state of solidification in which the cast part G can be de-molded.

Description

Method and apparatus for casting a casting from a molten metal

The invention relates to a method for casting a casting from a molten metal and to a device suitable for carrying out such a method. The molten metal processed according to the invention is in particular a light metal melt, preferably a melt based on aluminum or an aluminum alloy.

The properties of a casting are strongly influenced by the course of the solidification of the melt in the casting mold and the make-up required to compensate for the volume shrinkage. Thus, a particularly uniform distribution of properties shows when the Formfullung is carried out with melt in a continuous process while avoiding larger Schmelzenstromungen in the mold and the solidification then evenly distributed, on the opposite side of the feeder of the mold, uses.

High-quality castings of high quality can be produced by so-called "rotational molding". A design of this casting method which has been preserved in practice for the production of high-quality cast parts has been proposed in DE 100 19 309 A1. Accordingly, a molten metal containing Melting container docked with its upwardly directed opening to a downwardly pointing filling opening of a mold. Subsequently, the mold is rotated together with the firmly attached to it Schmelzenbehalter by approximately 180 °. In the course of the rotation, the melt passes from the Schmelzenbehalter in the mold. When the end position of the rotation is reached, the melt container is removed from the mold. The hot residual melt in the feeder area, which is now located at the top, can then continue to be effective under the action of gravity and can effectively compensate for the volume loss associated with the solidification of the melt.

By the rotation of the mold with the Schmelzenbehalter a complete filling of the mold is achieved with molten metal. The melt passes during rotation in that in the course of the mold rotation, the molten metal filled into the mold is uniformly exposed to gravity, safely in all areas of the mold cavity of the mold, which images the casting to be cast. In addition, the Gefuge of the casting is optimized due to the directional solidification, which is caused by the associated with the rotation orientation of the mold.

However, problems arise in the above-explained manner rotational molding, however, when particularly homogeneous solidification morphologies are required for cylindrical internal geometries. By first filling the mold against gravity and then turning it to cool Although, a quieter Formfullung and concomitantly better solidification result can be achieved. However, casting errors can occur even before turning, which usually manifests itself as bubbles or cold runs in the casting. These casting defects are attributed to the fact that the melt cools down so much even before the casting mold is rotated in the casting mold that uncontrolled solidification fronts form ("cold running") or the melt is packed into the casting mold with the inclusion of gas.

Against this background, the object of the invention was to provide a method and a device with which can be produced with high reliability in a particularly economical way high-quality, complex-shaped castings.

With regard to the method, this object has been achieved in that such a method according to the invention comprises the measures mentioned in claim 1. Advantageous embodiments of the inventive method are mentioned in the recited in claim 1 claims.

With regard to the device, the object stated above has been achieved according to the invention by the fact that such a device has the features specified in claim 12. Advantageous embodiments of a device according to the invention are specified in the claims related to claim 12. According to the invention, a casting mold mounted in a bogie is first provided for casting a casting from a molten metal (step a). This mold comprises a mold cavity forming the casting, a feeder system for feeding the mold cavity with molten metal, and a runner via which the feeder system is infillible with molten metal. In this case, the feeder system with respect to the mold cavity of the mold is arranged such that when filled into a full cast mold, the filling of the mold cavity with the molten metal via the feeder system is against the direction of gravity. At the same time provided for filling the molten metal infill of the sprue on a side surface of the mold is arranged so removed to its confluence with the feeder system that the Einfulloffnung the sprue in the respective full position of the mold is disposed above the junction in the feeder system.

Prior to filling, the mold thus provided is oriented to a full position in which molten metal filled in the runner flows through the runner as a result of gravity, the main flow direction of the molten metal forming an angle with the direction of gravity (step b). In this context, the "main flow direction" of the molten metal means the direction of flow in which the melt had to flow independently of the respective actual course of the sprue, in order to move directly from the infill opening to the mouth of the sprue into the feeder system reach. It is understood that the orientation of the mold in accordance with the invention predetermined full position can be made in each case in a separate operation, but that it is just as possible to already align the mold in the course of their provision that it meets the requirements of the inventive approach.

The mold aligned in full position is then filled with the molten metal until the casting mold including the runner is completely filled with molten metal (step c).

As soon as the casting mold is sufficiently filled, it is tightly closed by a stopper placed in the infill opening of the sprue channel (step d). Then, the mold is rotated to a solidification position in which, as a result of the action of gravity, the melt present in the feeder system prints on the melt present in the mold cavity (step e). In this position, the mold is held until the present in the mold molten metal has reached a certain solidification state (step f). Subsequently, the casting is removed from the mold (step g).

By the inventive manner of filling, the subsequent closing and keeping closed the mold and the rotation of the mold such that the metal melt contained in the feeder system of the mold prints on the melt forming the casting, casting errors are avoided. In addition to the particularly contributes to this calms down Befüllvorgang especially in that the metal melt contained in the mold from the end of filling and during the entire solidification process under metallostatic pressure remains. Thus, the melting of the melt in the cast part forming the mold cavity is counteracted by the melting column after closing in the sprue channel. At the same time, the tight closure of the mold allows the mold to be rotated immediately after completion of the filling process, without having to move the filling device itself or other expensive assemblies with the mold.

Due to the inventive alignment of the casting mold (step a) - c)) and the concomitant, with respect to the effective direction of gravity oblique orientation of their main flow direction, the molten metal flows as a result of correspondingly lower impact on the flow velocity gravitational force significantly slower through the runner, as would be the case if the main direction of flow of the melt and the direction of gravity were the same. Accordingly quietly runs in the inventive approach, the mold from the beginning of the filling process with molten metal full.

The particular in the known Rotationsgießverfahren just at the beginning of Befullens problematic turbulence and Stromungsungleichformigkeiten the melt are in accordance with the invention procedure clearly minimized. Even this simple measure contributes to a significant increase in casting quality.

By the casting mold is rotated after reaching a certain level of the molten metal during its further filling so that the main direction of flow of flowing through the runner metal melt is increasingly approaching the direction of gravity, let the gravity effect in the further course of the Befullvorgangs fully exploit. The amount of melt already present in the feeder system or in the sprue channel in this case brakes the melt newly flowing into the casting mold so that, even with a sprue channel swiveled increasingly in the direction of the gravity effect, a largely steady, uniform filling of the mold is ensured.

In addition, the rotation of the mold in the direction of the force of gravity during filling ensures optimum effectiveness of the metallostatic pressure at the time of closure of the mold. Therefore, a practical embodiment of the invention provides that the rotation performed during the filling process is ended when the main flow direction of the molten metal flowing through the sprue channel coincides with the effective direction of gravity.

The advantages that can be achieved particularly effectively by the main flow direction oriented obliquely at the beginning of the filling on the one hand and the rotation subsequently carried out during the filling process On the other hand, advantages obtained benefit when the rotation of the mold is started at the earliest when the mouth of the sprue in the feeder system is below the mirror of the molten metal filled in the mold. In this way, the risk of excessive vortex formation and the formation of gas bubbles in the casting is reduced to a minimum while optimally utilizing the advantages of a direction of gravity largely coinciding alignment of the main flow direction.

As a result, castings can be produced with the inventive method in a particularly economical manner with respect to the known casting process significantly reduced rejection rate, which meet even the strictest quality requirements.

According to the method explained above for the method according to the invention, an apparatus according to the invention for casting cast parts from a molten metal has a holder for holding a casting mold, a rotary drive for rotating the casting mold about an axis of rotation and a filling device for filling molten metal into an infill opening of the casting mold, wherein in such a device according to the invention a tracking device is provided which nachfuhrt the Fulleinrichtung during Einfüllens the molten metal caused by a rotational movement of the mold layer change of the filling of the mold.

For the filling of the mold, a conventional Gießloffel be used, which by means of a suitable Tracking device in one of the respective full position of the infill of the mold brought corresponding position and, if necessary, the associated with a rotation of the mold Lageanderung the Einfulloffnung is nachgefuhrt.

The method according to the invention and a device according to the invention for producing engine blocks for internal combustion engines are particularly suitable. In these and similarly complex shaped castings, it may be necessary to thermally pretreat certain sections of the mold so that the melt filled into the mold will exhibit the desired wetting or solidification behavior upon contact with the section concerned. A typical example of such mold sections are so-called "cylinder liners" or "cylinder beehives" which are cast in a light metal engine block in order to ensure sufficient wear resistance in the region of the cylinder openings of the engine block. These usually made of a steel material liners or bushings have a significantly higher thermal conductivity than the sand from which the casting cores or mold parts of the mold typically exist. By preheating the parts to be cast into the casting, improved wetting with the casting metal is achieved and the risk of thermal stress and undesirable formation of the structure is encountered.

The position of the axis of rotation about which the mold is rotated during the implementation of the method according to the invention is irrelevant, as long as it is ensured that the rotation results in a positioning of the casting mold and its sprue, in which the main direction of flow of the molten metal filled into the casting mold is aligned in the manner according to the invention. However, a particularly simple and practical embodiment of a device according to the invention used to carry out the method according to the invention results when the axis of rotation of the casting mold is oriented horizontally.

Likewise, let a particularly simple design of a device according to the invention can be achieved if the sprue of the mold is linear.

In addition, it contributes to a simple and cost-effective design of an inventive device when the

Filling opening of the sprue at a bottom of the

Mold is arranged, the opposite in the solidification state to a feeder system limiting

Upper side of the mold is arranged.

In order to achieve a largely free, versatile usability of a device according to the invention, its rotary drive should be able to rotate the casting mold through an angle of more than 180 °. The invention will be explained in more detail with reference to a drawing illustrating an exemplary embodiment.

FIGS. 1 to 10 each schematically show ten operating positions of a device 1 shown in a sectional view taken normal to its longitudinal axis for casting a casting G.

The casting G is an engine block for a four-cylinder internal combustion engine. Cast aluminum, an aluminum casting melt is used in the presently described exemplary embodiment.

The device 1 comprises a circular cross-section shown in the figures, mounted on two rollers 2,3 and rotationally driven by a drive, not shown, cylindrical casting cell Z, in which a flat mounting base 4 and a parallel and spaced apart to the mounting base 4 Fuhrungsplatte 5 are attached.

On the Fuhrungsplatte 5 associated top of the mounting base 4 is a base plate 6. This is part of the composite of several moldings and mold cores mold F. The base plate 5 has laterally recordings, in each of which sits a sash 7.8 with a correspondingly shaped paragraph , so that the sash 7,8 sit form-fitting manner on the base plate 6. From in the mold G typically existing front slides are here for reasons of clarity, only the scope of Gießzelle Z associated, arranged on the opposite sides of the base plate 5 slide 7,8 shown.

In the Fuhrungsplatte 5 is a parallel to the mounting base 4 facing underside of Fuhrungsplatte 5 extending pressure plate 9 is mounted so that it can be adjusted in the direction of the mounting base 4 to hold after completion of the assembly work the mold F, and of the mounting base. 4 can be moved away to dismantle the mold F and to demold the finished casting G after completion of the casting process.

Between the sash 7,8 then the cylindrical spaces of the engine block casting G to be cast in the radial direction enclosing cylindrical bushings B and the cores K are inserted in a conventional manner, which define within the casting G those channels and cavities, which are not of cast metal M should be filled.

On the pressure plate 9 associated top of the mold F then a sole core 0 is placed, the form-fitting hold the sash 7.8 at its upper, the Fuhrungsplatte 5 associated section and with the base plate 6, the sashes 7,8, the cores K, the cylinder liners B and the sole core O the mold cavity H of the mold F bounded.

On the sole core O, a feeder core S is finally placed, which includes a feeder system with a circumferential large-volume feeder channel 10, the when fully assembled feeder core S above the sash 7,8 runs. The feeder core S delimits an opening 11, via which the cylinder openings B respectively enclosed cylinder openings are accessible. The feeder channel 10 is connected via various gates 12 with the mold cavity H of the mold F.

In the mold is in the jargon also referred to as a "sprue bar" linear trained runner 13 is formed, which moves through the sash 7, the associated between the sash 7 and the mounting base 4, side portion of the base plate 4 and the feeder core 11 pulls and to the mounting base 4 is normally aligned and from a funnel-shaped in the mounting base 4 Einfülloffnung 14 straight on straight way to the feeder channel 10 of the feeder core S leads, in which he mouths with a junction 15.

After the feeder core S is mounted, the pressure plate 9 is lowered onto the mold F thus provided to secure the mounting position of the form-fitting interlocking parts and cores of the mold F.

Now, the casting cell Z is held with its held mold F by 180 ° about a coincident with the longitudinal axis of the mold F, horizontally oriented rotation axis X until the base plate 5 in the direction of action WK gravity seen above and the feeder core S is down. Accordingly, the Filling opening 14 of the sprue 13 on the now upper side of the mounting base 4th

After this position has been reached, a heating finger of a heating device 16 for inductive heating is in each case driven into the cylinder liners B in order to heat them to a prescribed temperature (FIGS. 3, 4).

After heating the cylinder liners B, the casting cell Z is again rotated counterclockwise about an angle of approximately 45 ° about the axis of rotation X. Accordingly, in this "filling position", the rectilinear sprue 14 is also inclined at an angle of approximately 45 ° to the direction of action WK.

Subsequently, the metal melt M to be cast is poured into the filling opening 14 of the sprue channel 13 by means of a casting device 17 designed as a ladle. Due to the inclination of the casting mold F, the melt M flows through the sprue channel 13 comparatively slowly and enters the feeder channel 10 of the feeder core S with correspondingly low kinetic energy. Their main direction of flow SR is aligned equal to the runner 13, so that the main flow direction SR of the flowing through the sprue 13 melt M is aligned at an angle of approximately 45 ° to the effective direction WK of gravity.

The filling of the inclined mold F with the molten metal M is continued until the junction 15 of the sprue 13 below the mirror in the Feeder channel 11 collecting molten metal M is located (Fig. 5).

If this state is reached, the casting cell Z is slowly rotated in the clockwise direction, until the runner 13 from its Einfulloffnung 14 to the junction 15 in the feeder channel 10 has vertically downwards.

The filling of the mold F with molten metal M is continuously continued during the rotation. For this purpose, the casting device 17 is nachgefuhrt by means of a tracking device T, which may be, for example, an actuator or a crane on which the casting device depends in each case, associated with the rotation of the casting cell Z Lageanderung the Einfulloffnung 14. When the end position of this rotation is reached, the main flow direction SR of the melt M coincides with the direction of action WK of gravity, so that the filling of the remaining sections of the mold cavity of the casting mold F proceeds with optimum utilization of gravity (FIGS. 7, 8).

Once a sufficient amount of melt is filled in the mold F, a plug 18 is placed in the Einfülloffnung 14 so that it is sealed (Figure 8).

Then, the casting cell Z is again rotated until the initial state (Fig. 2) is reached, in which the feeder core S seen in the direction of action WK the direction of gravity above and the base plate 5 are arranged below. The plug 18 while holding the mold F continues closed, so that leakage of melt M from the mold F is reliably prevented.

In this position, the mold F is held until the solidification of the casting G for demolding has progressed sufficiently far.

In the presently described exemplary embodiment, the casting mold F is thus constructed such that the feeder S of the casting mold F to be filled is arranged at least to a large extent below the mold cavity H of the casting mold F, so that the mold cavity H of the casting mold F initially filled against gravity becomes. Preferably, the entire casting mold F is already tilted during the filling process to the gate in order to reduce the speed of the molten metal M in the first filling and to achieve a uniform filling of the sprue 13 and the feeder S. For filling serves as a casting sliver formed pouring device 18, which, as shown, during the casting process with the rotation of the mold F can be mitgefuhrt.

After completion of the filling process, the sprue 13 extending upwards from the feeder S is closed and generates metallostatic pressure on the melt M present in the feeder S and the mold cavity, which prevents the melt M from backing back.

In the present exemplary embodiment, in the subsequent rotation, the molten metal M present in the feeder S causes the maintenance of the Metallostatic pressure of the molten metal M in the mold cavity. Casting defects, such as bubbles and cold runs, are thus excluded.

REFERENCE NUMBERS

I Device for casting the casting G 2.3 rolls

4 mounting floor

5 guide plate

6 base plate of the mold F 7,8 sash

9 pressure plate

10 Feeder channel of the feeder core S

II opening of the feeder core S

12 gates

13 sprue

14 infill

15 mouth of the runner 13

16 heating device

17 casting device

18 plugs

B cylinder liners

F casting mold

G casting

H Mold cavity of the mold F

K cores

M molten metal

0 sole core

S feeder core

SR main flow direction

T tracking device

WK effective direction of gravity

X axis of rotation

Z casting cell

Claims

PATENT AT SPRU

1. A method for casting a casting (G) from a molten metal (M) comprising the following steps:

a) providing a stored in a bogie mold (F) comprising a casting (G) forming mold cavity (H), a feeder system (10) for feeding the mold cavity (H) with molten metal (M) and a Ängusskanal (13) via which the feeder system (10) is infusible with molten metal, wherein the feeder system (10) is arranged with respect to the mold cavity of the mold (F) such that when the mold (F) is turned to a full position, the filling of the mold cavity (H) with the molten metal (M) via the feeder system counter to the effective direction of gravity, and wherein the filling opening (14) of the sprue (13) provided for filling the molten metal (M) is removed at a side surface of the casting mold (F) in such a way ( 15) is arranged in the feeder system (10) such that the infill opening (14) of the Gutter channel (13) in the respective full position of the mold (F) above its junction (15) in the feeder system (10) is arranged, b) aligning the mold (F) in a full position, in the runner (13) filled molten metal (M) flows through the runner (13) as a result of the action of gravity, the main flow direction (SR) of the molten metal (M) enclosing an angle with the direction of action (WK) of gravity, c) filling the mold in full-filling (FIG. F) with the molten metal (M) until the casting mold (F) including the runner (13) is completely filled with molten metal (M), d) closing the casting mold (F) through a runner (14) of the sprue (13 e) turning the sealed mold (F) into a solidification position, in which, due to the action of gravity, the melt (M) present in the feeder system (10) impinges on the mold cavity

(H) existing melt (M) prints, f) holding the mold (F) in the solidification position until the molten metal (M) present in the mold (F) has reached a certain solidification state, g) removing the casting (G).

2. The method according to claim 1, characterized in that the casting mold (F) after reaching a certain level of the

Metal melt (M) is rotated during its further filling so that the main flow direction (SR) of the molten metal (M) flowing through the runner (13) is increasingly approaching the direction of gravity.

3. The method of claim 2, wherein the rotation carried out during the filling process is terminated when the main flow direction of the molten metal flowing through the runner is in agreement with the effective direction of gravity.

4. The method according to claim 2 or 3, characterized in that the rotation of the mold (F) is started at the earliest, when the junction (15) of the sprue (13) in the feeder system (10) below the mirror of the mold (F ) filled molten metal (M) is located.

5. Method according to one of the preceding claims, characterized in that the molten metal (M) is filled into the casting mold (F) by means of a casting lamina (17).

6. The method according to claim 5 and one of claims 2 to 4 or 3, characterized in that the Gießloffel (17) of the rotation of the mold (F) is nachgefuhrt.

7. Method according to one of the preceding claims, characterized in that at least one section of the casting mold (F) is thermally treated before the molten metal (M) is introduced.

8. Method according to one of the preceding claims, characterized in that the casting (G) is an engine block for an internal combustion engine.

9. Method according to one of the preceding claims, characterized in that the axis of rotation (X) of the casting mold (F) is aligned horizontally.

10. Method according to one of the preceding claims, characterized in that the runner (13) of the casting mold (F) runs linearly.

11. Method according to one of the preceding claims, wherein the filling opening (14) of the sprue channel (13) is assigned to the underside of the casting mold (F).

12. An apparatus for casting a casting (G) from a molten metal (M), comprising a holder for holding a mold (F), a rotary drive to Turning the casting mold (F) about a rotation axis (X) and a filling device (17) for filling molten metal (M) into a filling opening (15) of the casting mold (F), characterized by a tracking device (T) which holds the filling device (17) during the filling of the molten metal (M) a position change of the filling opening (15) of the casting mold (F) caused by a rotational movement of the casting mold (F) is traced.

13. The device according to claim 12, wherein the filling device is a cast-slab (17).

14. The device according to claim 12, wherein the rotary drive is provided for freely rotating the casting mold (F) by an angle of more than 180 [deg.].

15. Device according to one of claims 12 to 13, d a d u r c h e c e n e c e s e s, in which the axis of rotation (X) of the mold (F) is aligned horizontally.