EP1498197B1 - Casting process for reciprocating-piston combustion engine block - Google Patents

Description

The invention relates to a method for casting crankcases made of cast iron for reciprocating internal combustion engines with a power up to 1500 hp and a crankcase weight up to 500 kg.

The crankcases of internal combustion engines of the generic order were previously either in normal standing position with cylinder head side (s) above - see 10 and 11 - or in a tilted horizontal position - see Fig. 9 - poured. The crankcase of V-type internal combustion engines have been basically only upright - as out Fig. 11 apparent - poured. As a result of this casting position in the crankcases, casting-related weak points arose, in particular at the upper edge regions of the castings, with the consequence of a certain amount of rejects or consequential damage in later engine operation.

It was therefore an object of the invention to provide a method for casting crankcases made of cast iron for internal combustion engines with the generic power and the generic crankcase weight, with the quality of the cast crankcase significantly improved and the reject rate is significantly reduced.

This object is achieved by a casting method with the features specified in claim 1.

Advantageous details of this method are given in the subclaims.

The advantages of the method according to the invention are given later in the context of the further description of the same with reference to the drawing.

Fig. 1

ein Kurbelgehäuse einer Reihenbrennkraftmaschine in erfindungsgemäßer Gießlage, hergestellt gemäß einer ersten Ausführungsform des erfindungsgemäßen Verfahrens durch Schwerkraftgießen,

Fig. 2

ein Kurbelgehäuse einer Reihenbrennkraftmaschine in erfindungsgemäßer Gießlage, hergestellt gemäß einer zweiten Ausführungsart des erfindungsgemäßen Verfahrens durch Schwerkraftgießen,

Fig. 3

ein Kurbelgehäuse einer Reihenbrennkraftmaschine in erfindungsgemäßer Gießlage, hergestellt gemäß einer dritten Ausführungsart des erfindungsgemäßen Verfahrens durch Niederdruckgießen,

Fig.4

ein Kurbelgehäuse einer V-Brennkraftmaschine in erfindungsgemäßer Gießlage, hergestellt gemäß dem erfindungsgemäßen Verfahrens durch Schwerkraftgießen oder Niederdruckgießen,

Fig. 5

ein Kurbelgehäuse einer Reihenbrennkraftmaschine in erfindungsgemäßer Gießlage, mit angesetzten Speisern und Entlüftung/Überlauf,

Fig. 6

ein Kurbelgehäuse einer Reihenbrennkraftmaschine in erfindungsgemäßer Gießlage, dargestellt in einer Gießform,

Fig. 7

ein Kurbelgehäuse einer Reihenbrennkraftmaschine in erfindungsgemäßer Gießlage, dargestellt in einer gegenüber Fig. 6 abgewandelten Gießform, und

Fig. 8

ein Kurbelgehäuse einer Reihenbrennkraftmaschine in erfindungsgemäßer Gießlage, hergestellt im Rahmen des erfindungsgemäßen Verfahrens durch Gradientenguss aus zwei unterschiedlichen Gussmaterialien.

In the drawing show:

Fig. 1

a crankcase of a series internal combustion engine in a casting layer according to the invention, produced according to a first embodiment of the method according to the invention by gravity casting,

Fig. 2

a crankcase of a series internal combustion engine in casting according to the invention, produced according to a second embodiment of the method according to the invention by gravity casting,

Fig. 3

a crankcase of a series internal combustion engine in a casting layer according to the invention, produced according to a third embodiment of the method according to the invention by low-pressure casting,

Figure 4

a crankcase of a V-type internal combustion engine in a casting layer according to the invention, produced according to the method according to the invention by gravity casting or low-pressure casting,

Fig. 5

a crankcase of a series internal combustion engine in inventive casting position, with attached feeders and vent / overflow,

Fig. 6

a crankcase of a series internal combustion engine in casting according to the invention, shown in a mold,

Fig. 7

a crankcase of a series internal combustion engine in inventive casting position, shown in a opposite Fig. 6 modified casting mold, and

Fig. 8

a crankcase of a series internal combustion engine in casting according to the invention, produced in the context of the inventive method by gradient casting of two different casting materials.

The inventive method for casting of crankcases 1 for reciprocating internal combustion engines with a power up to 1500 hp and a crankcase weight up to 500 kg is in principle that the crankcase 1 is turned upside down, so with the cylinder head side 2 lying down, in a mold. 3 is poured with substantially vertical mold division by introducing the liquid casting material from below. The vertical shape division of the mold 3 is in the FIGS. 6 and 7 indicated by the dash-dotted line 4. The gate 5 for the introduction of the liquid casting material is provided at the lowest point of the casting mold 3, in order to avoid turbulence in the casting material during the mold filling. The filling of the casting mold 3 with liquid casting material over the said lower gate 5 can either by low pressure from below into the mold 3 in pressed molding material - see Fig. 3 and 8th , Arrow 6 there - or by gravity from above via a sprue system 7 with casting material source (inlet funnel) 8 supplied cast material - see FIGS. 1, 2 and 8th , In the case of the V-crankcase 1 of Fig. 4 the casting material supply to the two gates 5 can also be done either low pressure or gravity guidance, insofar is the common Supply line designated 6 and 7 respectively. The use of casting filters in the gate 5 or Angusssysstem is possible at any time.

By cutting at the lowest point of the crankcase 1 to be cast, it is possible to achieve a low-turbulence and maximum calmed filling of the mold 3, wherein in the case of gray cast iron, a comparatively low, lying approximately between 1350 and about 1380 ° C casting temperature can be driven , Due to the low-turbulence mold filling in particular metal splash or areas where only a short wall wetting occurs, successfully avoided and it is therefore not necessary to melt these areas to create a pressure-tight connection. Due to this possible low casting temperature arise within the cast crankcase 1, a low temperature gradient and low residual stresses.

Because of the cylinder head side 2 given at the bottom of the casting mold 3, it is possible to minimize the addition of material in the area for later machining, because during the filling process, the oxides arising in the casting material do not settle in the region of the cylinder head surface zone, but rather due to their lower specific weight ascend to the top in less critical zones of the crankcase. In addition, in the cylinder head surface zone with its comparatively small wall thickness, the introduced casting material solidifies at high speed, as a result of which a structure with higher strengths than is customary at this point is established there.

Due to the casting position of the crankcase 1 according to the invention, it is also advantageously possible to cast the cylinder walls into the crankcase 1, which remain virtually free of porosities, gas bubbles or voids in the piston ring movement range, which casting defects can occur quite well in conventional upright casting position with cylinder head side 2 above , A particular advantage is that you can integrate the cylinder walls in such a way even with larger internal combustion engines easily, which allows a reduction in the crankcase length and thus a reduction in weight or alternatively, an increase in the cooling water space.

The sides of the water jacket on both sides of the cylinder walls to be enclosed are kept at a distance by means of metal support blocks, which are arranged comparatively far down in the casting mold 3 due to the cylinder head side 2 lying below and therefore can be melted cleanly in the casting material.

Due to the present invention vertical casting layer with the underlying cylinder head side 2 acts during casting of the crankcase 1, the largest metallostatic and static pressure in the cylinder head surface zone, which is not necessary feeding the cylinder head surface zone even when using prone to Lunkerung materials such as GJV and GJS.

Due to the given in the process according to the invention in the mold above crankshaft or bearing block area 9 of the crankcase 1 results in this area particularly good mechanical properties. This is because, during the casting process, the casting material ascending in the casting mold 3 has cooled sufficiently on reaching the crankshaft or bearing block region 9 that it only has a temperature close to the eutectic lying and thus in this region compared to others Component sets higher cooling rate and a finer microstructure with very high mechanical strength sets. This is particularly advantageous because crankcases should have the highest strengths generally in the bearing block area or crankshaft bearing area 9.

As a casting method for producing the crankcase 1, the green sand method or core block method or Kokillengussverfahren can be used.

In order to minimize the core sand volume, in particular in the crankshaft bearing area 9, it is possible to make this area hollow in the mold - see Fig. 6 , With 10 there is the crankcase core and designated 11 a receiving space for liquid casting material. Denoted at 13 are venting and / or casting material overflow channels.

Due to this hollow design of the crankcase area this can fulfill several functions. On the one hand, the inclusion of the overflow material that can get back over the overflows 13 in the receiving space 11, which ensures a continuous casting of the mold (3). In addition, the cup-shaped crank chamber core 10 is subjected to very high thermal loads, which later leads to easy desanding. On the other hand, it should be mentioned that - since the cavities are open at 12 upwards - into which, if not desired, no liquid casting material can enter. The going through the crankcase core shell is largely thermally decomposed, so that there is no problem in sanding there.

As Fig. 7 shows, the cavities in the mold 3 in the crankcase area with solid material, such. B. any shaped individual pieces or a contiguous piece of material 14 are filled, which forms a complaint weight or at least a part thereof. This can either rest only with gravity or optionally also be braced in addition to the frame or bottom of the mold 3. In the complaint weight 14 may also be integrated a holding or transport function, which can be used both in the core assembly and when removing the cast crankcase 1 from the mold 3. With 15 channels are designated, which serve the vent and / or as an overflow for liquid casting material or for attachment of feeders (if necessary).

If it should be necessary to feed due to the casting material used and / or the required quality to avoid voids, then the respective feeders 16 are preferably at the highest point of the crankcase to be cast 1, so the Ölwannenanlageflansch 17 and / or at a lower contrast Place as a support surface area 18 for the crankshaft bearing cap (not shown). Alternatively, however, these feeders 16 can also be integrated into the crankcase core 10 or injected into it.

When gravity casting of the crankcase 1, the sprue system 7 can either beside this - see for example Fig. 1 or by one or more of the cylinder bores bounded by the cylinder walls - see for example Fig. 2 - Be guided to the gate 5 out. In this case, the sprue after cooling of the casting material can be used as a transport hook. Due to the overhead crankcase alley, the sprue 8 can be integrated into this area, see the space 11 in FIG Fig. 6 ,

In addition, the inventive vertical casting position of the crankcase 1 with arranged below the cylinder head side 2 allows the realization of a graded structure within the crankcase 1, the use of z. B. two different cast materials can be realized. It will - like out Fig. 8 seen - in the area of the cylinder head surface zone and the adjoining upper cylinder wall areas a first material, for. B. GJL - see arrow 19 -, with better thermal properties poured off either via the sprue 8 and the Angusssystem 7 or a low pressure system 6 to the onsetting 5, whereas in the crankshaft or bearing block area 9 another Cast material, z. As GJS or GJV - see arrow 20 - is discharged with higher strength properties through a sprue 21 and a Angusssystem 22 to a tap hole 23 below the bearing block area. The zone of material transfer is in Fig. 8 marked with 24. An alternative pouring possibility for the second casting material can be displayed from the side outside. In this case, instead of the sprue 21 and Angusssystems 22 a laterally above the zubringendes crankcase 1 arranged sprue 25 and an outer Angusssystem 26 is provided, which leads to a lateral puncture 27.

With the method according to the invention can thus be cast crankcase, which are lighter and dimensionally accurate than those which were prepared in conventional manner.

Claims (11)

1. A method for casting crankcases made of cast iron for reciprocating-piston combustion engines having a power of up to approximately 1500 hp and a crankcase weight of up to approximately 500 kg, wherein the crankcase (1), upside-down with the cylinder head side (2) facing downwards in a casting mould (3) with essentially vertical mould parting (4), is cast by introducing the liquid casting material from below (5), and the gate (5) for introduction of the liquid casting material is located at the lowest point in the casting mould (3) in order to avoid turbulence during filling of the mould, and in that filling of the casting mould (3) with liquid casting material via said bottom gate (5) is carried out either by low pressure (6) from below or by gravity (7, 8) from above, with a casting material source (8) positioned above the highest point of the crankcase that is to be cast, characterized in that the casting material is grey iron which is introduced into the casting mould (3) at just a relatively low casting temperature of approximately 1350 to approximately 1380°C, so as to produce a small temperature drop in the crankcase (1) that is to be cast and, after cooling, small internal stresses therein.
2. The method according to Claim, characterized in that introduction of the casting material from below takes place directly with no additional redirection into the casting mould (3), and in that the cross section of the casting material supply line to the crankcase (1) that is to be cast is larger than the cross section of the runner, and thus filling of the casting mould (3) takes place with low turbulence and with minimum agitation.
3. The method according to either of the preceding claims, characterized in that, owing to the cylinder head side (2) being at the bottom of the casting mould (3), it is possible to minimize, in that region, the casting-related addition of material which must subsequently undergo chip-removing post-machining, because during the filling procedure the oxides arising in the casting material do not become embedded in the cylinder head surface region but rather rise upwards to less-critical regions of the crankcase (1), and in that furthermore, in the cylinder head surface region with its relatively thin walls, the introduced casting material solidifies more rapidly and forms there a higher-strength structure than is usually formed at these points.
4. The method according to one of the preceding claims, characterized in that the cylinder walls in the crankcase (1) are cast together with the same casting material and thus remain practically free from porosity, gas bubbles and voids in the piston ring movement region.
5. The method according to Claim 4, characterized in that the water jacket sides on both sides of the cylinder walls that are to be cast together are held spaced apart from one another by means of metallic supporting blocks which, owing to the cylinder head side (2) being at the bottom, are arranged relatively low in the casting mould (3) and hence can melt cleanly into the casting material.
6. The method according to one of Claims 1 to 3, characterized in that, owing to the vertical casting position of the crankcase (1) with the cylinder head side (2) being at the bottom when casting the crankcase (1), the greatest metallostatic and static pressure acts in the cylinder head surface region, and thus it is not necessary to feed the cylinder head surface region in question, even in the case of materials which tend to void formation, such as GJV or GJS.
7. The method according to one of the preceding Claims 1 to 5, characterized in that material which rises in the casting mould (3) during the casting procedure cools such that, when it reaches the crankshaft region or thrust bearing region (9) of the crankcase (1) which is at the top of the casting mould (3), it is at a temperature close to the eutectic and thus this crankcase region (9) experiences a higher cooling rate than normal and establishes a finer structure with very high mechanical strength.
8. The method according to Claim 1, characterized in that the crankcase (1) is produced using either the green sand method or the core block method or the shell mould casting method.
9. The method according to one of the preceding claims, characterized in that if, owing to the casting material used or the required quality, it is necessary to feed in order to avoid voids, the feeders (16) are preferably positioned at the highest component point of the crankcase (1), that is to say the oil sump bearing flange (17), and/or at a somewhat lower point such as a bearing surface region (18) for the crankshaft bearing cover, or alternatively are already integrated into the crank space core (10).
10. The method according to Claim 1, characterized in that, when gravity-casting the crankcase (1), the sprue system (7, 8) is either next to the crankcase (1) or is routed to the gate (5) via one or more cylindrical bores of the crankcase (1).
11. The method according to Claim 1, characterized in that, owing to the vertical casting position of the crankcase (1), with the cylinder head side (2) arranged at the bottom of the crankcase (1), it is possible to achieve a graduated structure by using two different casting materials (19, 20), wherein a material (19), e.g. GJL, having better heat-conduction properties is cast in the region of the cylinder head surface region and the adjoining upper cylinder wall regions, and a material (20), e.g. GJS or GJV, having higher strength properties is cast in the region of the crankshaft bearings or thrust bearings (9), and wherein the gate (23) for the casting material (20) provided in the crankshaft or thrust bearing region (9) is arranged above the lower gate (5) for the other casting material (19).

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