DE3419979C2 - Casting mold for cylinder blocks of internal combustion engines - Google Patents

Abstract

A casting mold for cylinder blocks (16) of internal combustion engines is described, with which the cylinder blocks (16) are cast in an upright position. The outer contour and the crank area of the cylinder block (16) are designed without or predominantly without undercuts, so that these contours with little or no core volume and the lower box shape (11) and the upper box shape (12) in the axial direction (18) of the cylinder bores of the cylinder block (16) can be demolded. The invention is characterized in particular by cost savings combined with better tolerance compliance.

Description

The invention relates to a casting mold for cylinder blocks of internal combustion engines with a lower box shape, an upper box shape, a water jacket core and optionally a head plate bore core, with a dividing line between the mold halves in the outer area of the mold halves runs horizontally.

Such cylinder blocks are usually cast from gray cast iron or aluminum. The outer contours In the case of gray cast iron blocks, compacted molding sand (equal to green sand, consisting of quartz sand, Bentonite, coal dust and water). The inner contours the Zyünderblocks are through suitable Cores formed, the cores of quartz sand or other sands with cold- and / or warm-hardening Binder systems (resin and hardener) are produced. The cores used in such casting processes are very expensive.

As far as is known, two types of such casting molds are currently in use. The most widely used casting mold works in such a way that the cylinder blocks are formed lying on their side in a lower box and an upper box will. The mentioned cores are placed in the open molds. Lower box and upper box become then folded up and it is poured off.

In another method, the cylinder blocks are cast standing on the base plate, namely using the cores listed above. Again, the two halves of the mold shown here that are arranged laterally, moved perpendicular to the axis of the cylinder bores.

The requirements of the automotive industry in terms of weight savings and thus compliance are considerable Tighter casting tolerances make it seem reasonable, from the ones outlined above and currently to deviate from the usual construction and casting principles and to break new ground. Both discussed above known casting processes have the following disadvantages:

Fluctuations in the distance between the upper box and the lower box are transferred to the full Scope of an entire block half with the resulting different wall thicknesses and weight differences of the cast cylinder block.

The crankcase area of the cylinder block must

are inevitably formed with the help of the crankcase core mentioned, its manufacture compared to Contours formed by means of green sand are considerably more expensive

Buoyancy forces during the mold filling process, especially in the water jacket area, are difficult to absorb.

The necessarily core-intensive process leads to

to high gas development during the casting and solidification process.

The invention avoids these disadvantages. It is the object of proposing a mold of the type mentioned, wherein the use of a portion of the relatively expensive cores by form-formed contours _e: sets can be. Nevertheless, the cylinder blocks cast with the casting mold according to the invention should be distinguished by tight tolerances and an overall reduced consumption of material, combined with a reduced production time.

To solve this problem, the invention is characterized in that the lower box shape and the Qberkäster.form are designed and arranged so that the cylinder block is cast upright and that the lower box shape and the upper box shape in axial Direction of the cylinder block can be demolded, the lower box shape also the inner area of the Can shape crankcase.

You can now produce the crankcase area in green form. The distance and the width dimension the bearing blocks of the cylinder block can be manufactured with higher accuracy. It can also with smaller machining allowances can be worked. The housing wall thickness can be in the nominal dimension and in their Tolerance field compared to cylinder blocks, which are conventionally cast, are considerably narrowed. The water jacket core no longer needs to be supported by core supports. Nor does it receive any deformation during the casting process, as is the case with the known casting mold with a horizontal arm. Opening of the cylinder block the case is because the water jacket core is upright. Furthermore, there is a circular cylinder outside diameter enables. This can be reduced to the minimum construction size. Total let The innovative casting mold enables closer manufacturing tolerances to be achieved, combined with noticeable weight savings.

You can see the outer contour of the cylinder block and its crankcase area without undercuts form, whereby the demolding in the axial direction is then easily made possible. But are, for example For design reasons, such undercuts are present, so are in the undercuts Separate cores are used, which then allow the axial demolding of the upper box shape and the lower box shape enable.

It is preferred if the horizontal outer area of the dividing line between the upper box shape and the lower box shape runs in the area of the base plate of the cylinder block. This will reduce the influence of constant fluctuations in the distance between

- .the upper boxfprm. and_the lower box form complete-

. dig eliminated ^ Diesei "Ahpr, dnung;.. is further characterized prefer-> hen when is wiedies often the case, the cylinder block in question to the base plate is provided with an outwardly facing flange at the free end of the crank chamber wall, of a connection surface to the oil pan In general, the arrangement of the horizontal

len dividing line between the two forms can be said that this can of course also run further above the base plate of the cylinder block, provided that The principle of demoldability in the axial direction is retained, and if one does not do so attaches great importance to the elimination of those disadvantages caused by the inevitable fluctuations in distance arise between the two mold halves.

It should be mentioned that the casting mold according to the invention for cylinder blocks of internal combustion engines in general is suitable, namely both for passenger cars as well as for trucks including ship propulsion systems, etc.

The invention is explained in more detail below with reference to an exemplary embodiment from which further result in important characteristics. To illustrate the advantages of the invention, FIG. 1 and 2 the above already explained two known casting molds shown. In detail shows

F i g. 1 schematically shows a first embodiment of a known casting mold with a horizontal dividing line;

FIG. 2 also schematically shows a second known casting mold with a vertical dividing line; FIG.

3 schematically shows a casting mold according to the invention with a horizontal dividing line on the outside without undercuts and

F i g. 4 schematically shows a partial section of a casting mold according to the invention with a horizontal dividing line in the outer area, with core-shaped undercuts will.

The in F i g. The known casting mold shown in FIG. 1 has a lower box mold 1, an upper box mold 2, and a crankcase core 3, a head plate bore core 4 and a water jacket core 5. Between a dividing line 6 the mold halves 1, 2 runs horizontally and coincides with the longitudinal axis of the cylinder block 7 to be cast together.

The outer contour 8 of the cylinder block has projections in the axial direction, so that it can be removed from the mold in the axial direction Direction would not be possible. The two mold halves 1, 2 are therefore removed from the mold in a radial, perpendicular direction, d. H. in the direction of arrow 9.

The also known casting mold shown in FIG is basically constructed like that of FIG. 1, wherein one only differs from FIG. 1 pours the cylinder block upright. Also in Fig. 2 are the two halves of the mold 1, 2 in the radial direction, i.e. H. in the direction of arrow 9, demolded.

The casting mold according to the invention according to FIG. 3 has a lower box shape 11, an upper box shape 12, a Headstock Bohrerkerr 13 and a water jacket core 14. It can be seen that the shape of the lower box also has the function of the otherwise existing crankcase core takes over. A dividing line 15 between the mold halves 11, 12 runs horizontally in the outer area, namely in the plane of the base plate surface of the cylinder block 16. It then follows inwardly the shape of the crankcase area. It can also be seen that the outer contour 17 of the cylinder block has no undercuts, so that the mold halves ■; jM ;; 12 'in the direction of arrow 18, d. H. in the axial direction f of the cylinder block, can be demolded. (The axis is indicated at item 19.)

It can also be seen that the crankcase area of the cylinder block also has no undercuts, so that the lower caster mold U can be demolded downwards without any obstacles,

Because the otherwise existing crankcase core is omitted and because of the lower box shape made from green sand 11 replace! is, the gas development during the casting process, which is otherwise based on the heating of the crankcase core, is significantly reduced. Furthermore can the wall thicknesses in all block areas are reproducibly produced with previously unattainable tolerances will.

The casting mold according to the invention in FIG. 4 shows a Modification of those according to FIG. 3.

It can be seen that the crankcase area and the outer cone are substantially formed and the Undercuts are formed by cores 20, 21 to be introduced into the lower and / or upper box shape 11, 12 will. A draft angle 22 between the upper mold half 12 and the core 21, which is aligned with the axis 19 includes an acute angle that opens downwards, as well as radii 23 on shoulders of the lower mold half 11 and on the core 22 also facilitate demolding in the direction of arrow 18.

For this purpose 4 sheets of drawings

Claims (2)

Patent claims: 1. Casting mold for cylinder blocks of internal combustion engines with a lower box shape, an upper box shape, a water jacket core and possibly. with a headstock bore core, with a dividing line between the shapes on the outside of the forms runs horizontally, characterized in that the lower box form (II) and the upper box mold (12) are designed and arranged so that the cylinder block (16) is cast upright is, and that the lower box shape (11) and the upper box shape (12) in the axial direction (18) of the Cylinder bores of the cylinder block (16) can be demolded, the lower box shape (11) also shapes the interior of the crankcase. 2. Casting mold according to claim 1, characterized in that the horizontal outer region of the Separation line (15) in the area of the base plate of the cylinder block (Ifcrt runs.