Method for casting cast parts from a molten metal

Abstract

A casting mold is pivoted about a horizontal pivot axis for casting cast parts in a casting machine. The casting mold has a lid and a reference side wall. A main plane is placed into the reference side wall. A tundish is coupled to the casting mold and the casting mold is then pivoted into a pouring-in position. The tundish filled with a molten metal portion is pivoted with the casting mold about the pivot axis, so that the molten metal flows into the casting mold. An angle 1 enclosed between the main plane of the reference side wall and a bath level of the molten metal portion in the tundish is constantly <180 until the melt hits the bottom of the casting mold.

Claims

1. A method for casting cast parts from a molten metal using a casting mould pivotably mounted about a horizontally aligned pivot axis in a casting machine, the casting mould defining a mould cavity shaping the cast part to be cast in each case and having a lid delimiting the mould cavity on its one side, on which at least one filling opening is provided for feeding molten metal into the mould cavity, a reference side wall abutting on the lid and delimiting the mould cavity on its one side with wall areas, into which a main plane of the reference side wall running axially parallel to the pivot axis is placed in such a way that its alignment is approximated to the average of the alignments of the wall areas, which also in each case extend in a direction aligned parallel to the pivot axis, and a bottom whose bottom areas assigned to the mould cavity shape the bottom end of the cast part, and using a tundish which on its pouring-in side for pouring the molten metal into the tundish and on a pouring-out side abutting on the pouring-in side and on a bottom of the tundish is at least in sections open in each case, via which the molten metal filled into the tundish in casting operation flows out of the tundish into the casting mould, comprising the following production steps: arranging the tundish on the casting mould in such a way that its pouring-out side butts against the lid of the casting mould and the bottom of the tundish is assigned to the reference side wall, wherein the pouring-in opening of the casting mould and the open section of the pouring-out side at least overlap one another; pivoting the casting mould into a pouring-in position, in which the main plane of the reference side wall encloses an angle 1 that is less than 180 with a bath level of a molten metal portion to be filled into the tundish and the bath level of the molten metal portion to be filled into the tundish is located below the filling opening of the casting mould; filling the tundish, which is in the pouring-in position, with the molten metal portion which is sufficient for filling the casting mould; and pivoting the casting mould with the tundish arranged on it about the pivot axis into a pivot direction, in which as a result of the pivoting molten metal flows out of the tundish into the casting mould, wherein the pivoting is continued until an end position is reached, in which the casting mould is filled with molten metal, and wherein the angle 1 enclosed in each case between the main plane of the reference side wall and the bath level of the molten metal portion, which is contained in the tundish in each case, is at least constantly less than 180 until the melt flowing into the casting mould hits the bottom of the casting mould, wherein a recess is formed into the lid of the casting mould, which when the casting mould is completely pivoted takes up a melt volume which serves as a feeder.

2. The method according to claim 1, wherein the bottom of the tundish is flat on its side facing the molten metal.

3. The method according to claim 2, wherein a bottom area formed on the inside of the tundish encloses a right angle with the bottom of the casting mould.

4. The method according to claim 2, wherein the pouring-out side of the tundish assigned to the casting mould is open.

5. The method according to claim 2, wherein the filling opening of the casting mould extends over the side of the lid of the casting mould assigned to the tundish.

6. The method according to claim 2, wherein an inflow surface is formed on the side of one of the closed walls of the tundish facing the molten metal, this inflow surface being inclined starting from the bottom in the direction of the upper free edge of this wall and at which the molten metal is directed when the molten metal is poured into the tundish.

7. The method according to claim 2, wherein the angle 1 is 120-160 when the casting mould is in the pouring-in position.

8. The method according to claim 1, wherein a bottom area formed on the inside of the tundish encloses a right angle with the bottom of the casting mould.

9. The method according to claim 1, wherein the pouring-out side of the tundish assigned to the casting mould is open.

10. The method according to claim 1, wherein the filling opening of the casting mould extends over the side of the lid of the casting mould assigned to the tundish.

11. The method according to claim 1, wherein an inflow surface is formed on the side of one of the closed walls of the tundish facing the molten metal, this inflow surface being inclined starting from the bottom in the direction of an upper free edge of this wall and at which the molten metal is directed when the molten metal is poured into the tundish.

12. The method according to claim 1, wherein the angle 1 is 120-160 when the casting mould is in the pouring-in position.

13. The method according to claim 1, wherein two or more ingates open out onto the lid as pouring-in openings, via which the melt flows into the mould cavity of the casting mould when pivoting into the end position.

14. The method according to claim 1, wherein the molten metal when pivoting into the end position runs directly against the lid of the casting mould and flows into the respectively available pouring-in opening there.

15. The method according to claim 1, wherein the pivot angle covered by the casting mould with the tundish arranged on it between the pouring-in position and the end position is 110-160.

16. The method according to claim 1, wherein the pivot axis runs through or close to the bottom of the casting mould.

17. The method according to claim 1, wherein the molten metal is a light metal melt.

18. The method according to claim 1, wherein the cast part to be cast is a cylinder head or a crankcase for an internal combustion engine.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention is explained in more detail below with the aid of figures illustrating an exemplary embodiment, in each case there being shown schematically

(2) FIG. 1 a casting machine for casting cast parts pivoted into a normal position in a side view;

(3) FIG. 2 the casting machine according to FIG. 1 in a plan view;

(4) FIG. 3 the casting machine according to FIG. 1 in a starting position with the tundish arranged on it, in a side view;

(5) FIG. 4 the casting machine according to FIG. 1 in the pouring-in position in a side view;

(6) FIG. 5 the casting machine according to FIG. 4 when melt is poured into the tundish, in a side view;

(7) FIGS. 6-8 the casting machine according to FIG. 1 in different pivot positions in a side view and

(8) FIG. 9 the casting machine in the end position reached after the pivoting movement has been completed, in a side view.

DETAILED DESCRIPTION OF THE INVENTION

(9) The casting machine G has a base plate 2 which is mounted in a base frame 1 and which can be pivoted about a horizontally aligned pivot axis HS by means of a pivot drive 3. When the casting machine G is in the starting position (FIG. 1), the base plate 2 is aligned horizontally.

(10) A casting mould 5 for casting a cylinder head, a crankcase or an engine block for an internal combustion engine, for example, and composed as a core package of a plurality of casting cores 6-11 precast in a known way is built onto a mounting surface 4 formed on the upper side of the base plate 2. The moulding material which the mould cores 6-11 consist of is a mixture of a moulding sand, optionally present additives and a binder which is solidified by chemical treatment or by addition of heat, in order to achieve the required mould stability. Of course, individual cores or parts of the casting mould 5 can also consist of other materials, so that that they can be reused. Equally, chills (not illustrated here) or suchlike can be present in the casting mould 5, so that a directed solidification of the melt filled into the casting mould 5 can be produced.

(11) The casting mould, which for the sake of clarity is only illustrated here in rough detail, comprises a bottom 6, side walls 7, 8 which form the lateral, outer end of the casting mould 5, a lid 9 and casting cores 11 which are arranged within the mould cavity 10 defined by the casting mould 5 and which form channels and/or hollow spaces in the cast part to be cast. The bottom 6 and the side walls 7, 8 can, for example, be produced as casting cores consisting of moulding material or as permanent casting mould parts consisting of a metal material, such as a heat-resisting steel material, or consisting of a copper material. With regard to the removability from the mould of the cast part to be cast in the casting mould 5, however, only the lid 9 typically consists of moulding material, whereas the bottom 6 and the side walls 7, 8 are designed as permanent mould parts.

(12) A trough-like recess 12 is formed into the lid 9 from its top side, in the bottom of which recess 12 ingates 13 serving as filling openings end, via which the mould cavity 10 of the casting mould 5 can be filled with melt.

(13) The casting machine G additionally comprises a pivoting and positioning device 14 which is also mounted on the base plate 2. By means of the device 14, a tundish 15 can be pivoted between a standby position, in which it is in each case outside the area which is required before the casting process for building the casting mould 5 onto the base plate 2 or after the casting process has been completed for removing the casting mould 5, and a pouring-in position, in which it is arranged with its pouring-out side 16 abutting on the outside 17 of the lid 9.

(14) The tundish 15, which is open on its pouring-out side 16 and top side O and is manufactured from a fire-proof material, defines a tundish area 22 with its bottom 18, two longitudinal side walls 19, 20, which are arranged parallel to one another and extend along the bottom 18, and a rear wall 21. The rear wall 21 extends parallel to the open pouring-out side 16 between the ends of the longitudinal side walls 19, 20 assigned to it and has on its side assigned to the tundish area 22 an inflow surface 23 which starting from the flat bottom area of the bottom 18 assigned to the tundish area 22 rises obliquely in the direction of the free upper edge of the rear wall 21.

(15) In its operating position the tundish 15 is held by the device 14 on the casting mould 5 such that the tundish 15 with the respectively free face sides of the longitudinal side walls 19, 20 and of the bottom 18 sits tightly on the assigned contact surfaces of the lid 9 of the casting mould 5.

(16) During assembly of the casting mould 5, the base plate 2 with the casting mould 5 built onto it is in the starting position. The pivot angle 2 about the pivot axis HS is equal to 0 in this position.

(17) After the casting mould 5 has been built onto the base plate 2, the device 14 places the tundish 15 with its pouring-out side onto the lid 9 of the casting mould 5 (FIG. 3). The device 14 holds the tundish in this position on the casting mould 5 until the casting process is complete.

(18) When the tundish 15 is positioned in place on the casting mould 5, the side wall 7 of the casting mould arranged closest in this position to the bottom 18 of the tundish 15 represents the reference side wall which is critical for determining the pouring-in position in which the tundish 15 is filled with melt. The side wall 7 has wall areas 24 on its side assigned to the mould cavity 10, which form mould areas on the assigned lateral outer surface of the cast part to be cast. Each of the wall areas 24 has a certain orientation in relation to the pivot axis HS, which in each case can be indicated by a vector VW applied to the respective wall area 24 and aligned perpendicularly to the pivot axis HS.

(19) A virtual main plane HE is placed into the side wall 7 in order to determine the pivot angle 2, about which the casting mould 5 with the tundish 15 has to be pivoted from the starting position into the pouring-in position, this main plane HS, on the one hand, extending parallel to the pivot axis HS and, on the other hand, being aligned in such a way that its alignment is approximated to the average of the alignments of the wall areas 24 indicated by the vectors VW, which in each case also extend in a direction aligned parallel to the pivot axis.

(20) The pivot angle 2, about which the casting mould 5 is pivoted after coupling the tundish 15 in the example illustrated here anticlockwise about the pivot axis HS from the starting position shown in FIG. 3 into the pouring-in position shown in FIGS. 4, 5, is now selected such that the angle 1 enclosed between the top of the bath level BS (which at this time is still virtual) of the molten metal portion S to be filled into the tundish 15 and the main plane HE of the reference side B is less than 180. In the exemplary embodiment illustrated here, this angle 1 is, for example, 135-165, whereas the pivot angle 2 is in the range from 110-160, in particular from 120-150.

(21) It is additionally taken into account when determining the pivot angle 2 that the bath level BS, when the casting mould 5 and tundish 15 are pivoted into the pouring-in position, is below the ingate 13 of the casting mould 5 which is arranged in this position at the bottommost in the lid 9.

(22) After the combination consisting of the casting mould 5 and tundish 15 has been pivoted about the angle 2 determined in the above explained way into the pouring-in position, the molten metal portion S is filled into the tundish 15 by means of a conventional pouring ladle 25. An aluminium cast alloy is used as the molten metal here, as is usually used for casting parts for internal combustion engines. In order to ensure that the filling of the tundish 15 is as smooth and as free from turbulence as possible, the pouring stream 26 of molten metal leaving the pouring ladle 25 is directed at the inflow surface 23 of the tundish 15. The stream 26 striking there with the removal of kinetic energy is diverted in the direction of the bottom area of the tundish 15 and in this way hits the melt S already present in the tundish 15 in a comparably smooth flow distributed over a larger width.

(23) After filling of the tundish 15 has been completed, the casting mould 5 with the tundish 15 is pivoted back clockwise towards the starting position. With increasing pivoting more and more melt S flows into the mould cavity 10 of the casting mould 5 until finally when the end position (=starting position) is again reached the molten metal portion S is completely filled into the casting mould 5. Excess melt volume is taken up by the recess 12 in the lid 9. The melt volume collected there when the casting mould 5 has been completely pivoted serves as a feeder to compensate for material shrinkage occurring in the course of solidification of the melt.

(24) The pivot angle 2 selected for the pouring-in position was set in a manner according to the invention such that the angle 1 between the bath level BS and the main plane HB of the side wall 7 is constantly less than 180 until the melt S flowing into the casting mould 5 hits the bottom 6 of the casting mould. By means of this setting, it is ensured that the melt S at an acute angle runs horizontally against the wall areas 24 of the reference side wall (side wall 7). In this way, the casting mould 5 can be filled smoothly and in layers, which provides optimum conditions for forming a uniform microstructure in the finished cast part. Foam formation on the melt is to the greatest possible extent prevented. The cast part obtained is also to the greatest possible extent free of inclusions or other damaged spots due to the smooth filling operation. Contaminants and oxides which could cause such inclusions collect in an upper layer of the feeder volume SV formed from residual melt S in the recess 12, whereas at most small residues remain behind in the tundish 15, which can be easily removed.

REFERENCE SYMBOLS

(25) 1 Angle enclosed between the top of the bath level BS and the main plane HE 2 Pivot angle BS Bath level of the molten metal S present in the tundish 15 G Casting machine HS Pivot axis HE Main plane of the reference side wall (side wall 7) S Molten metal SV Feeder O Top side of the tundish 15 VW The alignment of the vectors indicating the wall areas 24 1 Base frame 2 Base plate 3 Pivot drive 4 Mounting surface 5 Casting mould 6 Bottom 7 Side wall (Reference side wall) 8 Side wall 9 Lid 10 Mould cavity 11 Mould core 12 Recess 13 Ingates 14 Pivoting and positioning device 15 Tundish 16 Pouring-out side 17 Outside of the lid 9 18 Bottom of the tundish 15 19, 20 Longitudinal side walls of the tundish 15 21 Rear wall of the tundish 15 22 Tundish area 23 Inflow surface of the tundish 15 24 Wall areas of the side wall 7 25 Pouring ladle 26 Pouring stream