EP1952914A2 - Device and core for manufacturing a cylinder crank case - Google Patents

Abstract

The crankcase-producing device is composed of fixed and movable half-molds forming a casting cavity (14, 21). The core (1) has apertures into which the holding projections (5, 6, 7, 8, 9, 10, 11, 12) on the mold parts extend, so that the core is fixed in position, thus forming the core for the water jacket of the crankcase.

Description

The invention relates to a device and a sand core for producing a cylinder crankcase in closed-deck construction, wherein the device is formed of stationary and movable moldings and moldings form a mold cavity and the sand core is positively held in at least one molding and the sand core at least one Opening has, in which a retaining projection of the holding mold part extends; so that the sand core is fixed in the device and the sand core forms a water jacket core of the cylinder crankcase.

The stiffness of a cylinder area of a cylinder crankcase is very much determined by the design of the cylinder deck. If the cylinder cover plate is closed except for the passage of coolant or shaking out of the sand core required for the formation of the water jacket, this is referred to as the closed deck. Since the water jacket here is almost completely closed by the casting material to be filled into the casting cavity of the device, that is, in other words, the water jacket core is located inside the cylinder crankcase, there is a problem in positioning the sand core in the casting position during the casting process. Arranging cores in the casting mold presents problems, in particular in die-casting processes. There is a risk of core displacements during filling of the melt, with cores which span a greater distance without core seating, ie without support against the casting surface a high risk of core deformations, which in turn can lead to partial core relocations. Here, the term die casting process is to be understood in the broadest sense. This is to be understood as meaning the conventional die casting process in which the melt is shot into the mold under pressures of more than 500 bar, but also the squezze casting, in which the melt is essentially filled without pressure into the mold and then under high pressure Pressure of several 100 bar is brought to solidification, as well as the so-called low pressure process. In the die casting process, the dynamic forces of the liquid metal filled into the casting cavity on the sand core, in relation to the core displacements, play a crucial role.

A method for securing against relocation is in the DE 197 52 518 described. Described is a die casting method for producing castings in a casting mold using post-casting cores, particularly sand or salt cores, while preventing the cores from floating in the casting process by using infiltratable bodies to support the cores in the casting mold are fixed on the sand or salt core and thus fix the cores in the mold in accordance with the position.

A sand core with integrally formed on the sand core lateral elevations is in the EP 1 649 951 described. The elevations are held in the mold parts of the device, so that the sand core is used at the same time to form the water jacket core and to fix the position of the water jacket.

A device and a sand core, on which the two-part form of claim 1 is based, is in EP 0 788 855 disclosed. Disclosed is a device and a sand core for producing a cylinder block in closed-deck construction, which has a cylinder top plate and is formed with a plurality of laterally juxtaposed cylinder liners surrounded water jacket, the water jacket an upper End partially closed at the cylinder top plate to form the window and partially closed by bridge areas. The device consists of several moldings which define a casting cavity for casting the cylinder block. The apparatus has a number of retaining projections extending integrally from a molding to the casting cavity in the axial direction of the cylinder liner, and the sand core is formed with a number of retaining bores complementary to the respective retaining projections and arranged to extend holding protrusions extending into them for holding the sand core at a particular location of the casting cavity during casting. The areas of the sand core into which the retaining projections project have a thickened wall area, so that a sufficient stability of the sand core is ensured. In addition to the axial fixation of the sand core by the holding projections core projections are formed on the sand core, which protrude according to the prior art in other moldings of the device and fix the sand core positionally correct. This has the disadvantage that the sand core is thickened in the region of the retaining projections projecting into it, which adversely affects a structural design of the water jacket core.

The object of the invention is to overcome the disadvantages of the prior art and to provide a sand and / or salt core, which allows a positionally secure positioning of the sand core in the device and which is also inexpensive to manufacture. In addition, the object of the invention should be dimensionally stable even with thin-walled sand cores and make no additional core storage required in slide areas. In addition, the device and the sand core to allow high gating speeds of the casting metal in the die casting process.

The object of the invention is achieved in that the holding projection at least partially forms part of an outer contour of the water jacket core. Due to the inventive structure of the sand core and the Retaining projections on the sand core holding the molding is now created the opportunity to fix the sand core dimensionally stable even with thin-walled cores on the molding. In addition, in contrast to the prior art, a more cost-effective production of the sand core is made possible in that only recesses are present as openings in the sand and / or salt core. Also, the reduction of the sand needs for the sand core has a cost-reducing effect on the production of the cylinder crankcase.

Another advantage arises when the holding projections in the holding mold part in its entire extension in the direction of the sand and / or salt core forms part of the outer contour of the water jacket core. As a result, on the one hand, the production of the sand and / or salt core and the fixation of the core on the molded part is facilitated. If, as proposed according to the invention, a complementary geometric profile is formed between the retaining projection and the core, then the core undergoes an additional fixation on the retaining molded part.

Figur 1

eine dreidimensionale Ansicht auf einen erfindungsgemäß ausgebildeten Sandkern in einem Formteil, mit angedeutetem Zylinderkurbelgehäuse,

Figur 2

eine Detailansicht in einem Bereich eine Zylinderbohrung,

Figur 3

eine Detailansicht gemäß dem Schnitt III aus Figur 1 in einem Bereich zwischen Haltevorsprung und Sandkern und

Figur 4

eine Detailansicht gemäß dem, Schnitt IV aus Figur 1 im Bereich einer Öffnung beziehungsweise Ausnehmung im Sandkern.

The invention will be explained in more detail with reference to drawings in one embodiment. It shows:

FIG. 1

3 shows a three-dimensional view of a sand core formed according to the invention in a molded part, with an indicated cylinder crankcase,

FIG. 2

a detailed view in a region of a cylinder bore,

FIG. 3

a detailed view according to the section III from FIG. 1 in an area between retaining projection and sand core and

FIG. 4

a detailed view according to the, section IV FIG. 1 in the region of an opening or recess in the sand core.

In the FIG. 1 a sand core 1 and a sand core holding mold part 2 is shown, wherein the sand core 1 is shown in its position in the position as it is held in the apparatus for producing a cylinder crankcase 3. As a dash-and-dot line, the position of the sand core with respect to a cylinder crankcase 3 is reproduced therein. The cylinder crankcase 3 is shown in this view from its underside. Thus, the indentations 4 in the finished cylinder crankcase form the bearing block for the crankshaft. The molded part 2 of the device is, for example, a stationary molded part 2, so that the sand core 1 is inserted into the device. In this case, retaining projections 5 to 12 extend from the lower tool 2 in the direction of the sand core 1. In this case, the retaining projections form 5 to 12 parts of the outer contour of the water jacket core 1. According to the invention, the openings in the cylinder cover plate are formed by the retaining projections 5 to 12 of the lower tool 2. The openings 13 serve on the one hand for the passage of water from the cylinder crankcase to the cylinder head and also serve to remove the molding material of the sand and / or salt core 1 from the cylinder crankcase.

The mold cavity 14 between the sand and / or salt core 1 and the lower tool or holding mold part 2 is filled with cast metal. Cast metal is the usual aluminum and aluminum alloys used for cylinder crankcases, as well as magnesium and magnesium alloys, as well as hybrid forms of the same conceivable. Like from the FIG. 1 not only the position of the water jacket core 1 in the mold cavity 14 is positioned to form the cylinder crankcase 3 positionally but also fixed by means of the retaining projections 5 to 12.

In the in the FIG. 1 illustrated embodiment, the entire extent A, as exemplified on the retaining projection 5, a part of the outer contour of the water jacket core after. That is, the retaining projection 5 corresponds in the course of the inner and outer outer contour of the water jacket core 1. Alternatively, it is conceivable, and as in the FIG. 2 shown that the retaining projection 5 'only in the sand core 1' projects into it and the sand core 1 'extensions 15 which protrude into recesses 16 of the lower tool 2, so that an alternative storage and fixation of the sand core 1' in the device, or the molding 2 'is given.

On the molding, or lower tool 2 on the one hand, the retaining projections 5 to 12 are formed, but the lower tool has on the other hand also cylindrical elevations 17, 18, 19, 20, the cylinder bore 17, 18, 19, 20 form in the finished cylinder crankcase. The mold cavity 21 between the cylinder elevations 17, 18, 19, 20 and the water jacket 1 is poured with the cylinder crankcase 3 forming light metal material.

A further advantage according to the invention results when the boundary surface 22, 23, as exemplified in FIGS FIGS. 1 and 2 drawn, provided with a geometric profile. Two different geometric profiles between the water jacket core 1, 1 'and the retaining projection 5, 5' to 12 is in the FIG. 3 played. The FIG. 3 shows a sectional view through the holding projection 5, 5 ', and the sand core 1, 1', wherein two different geometric profiles are shown. In one embodiment, the sand core 1, 1 'projects into the retaining projection 5, 5' and in another embodiment the retaining projection 5, 5 'projects into the sand core 1, 1'. It goes without saying that the two illustrated embodiments are exemplary. Of course, any geometric shapes, such as peaks, bevels, grooves, bulges can be formed as profiles. The prerequisite for this is that the sand core 1, 1 'on the holding projection 5, 5' can be pushed. In this case, it is also conceivable according to the invention that the holding projection 5, 5 'is conical, and the core 1, 1' has a conical recess, so that the sand core 1, 1 'only in its final position on the molded part 2, 2' completely to the holding projections 5, 5 'to 12 is applied.

The device consists of stationary and movable moldings, wherein on a central stationary holding mold part 2, 2 'of the water jacket core 1, 1' is applied. The laterally mounted movable moldings, which can also be designated as a slide, close the casting cavity, in which they move laterally toward the water jacket core 1. According to the invention it is now proposed in the sand core 1, 1 'openings or recess 24, 25 and bring additional elevations or stamp 26 to secure the additional core storage on the movable moldings in the openings 24, 25 with closed tool or closed device in protrude the sand core 1 to position this positionally correct in the casting device. In the FIG. 4 is a section along the line IV through the sand core 1 and the opening 24 shown. Also in this case two alternative embodiments are described according to the invention. In the FIG. 4 is the sand core 1, 1 'and the punch 26 which is attached to the movable mold half of the device is shown. It is inventively conceivable, as in the FIG. 4 shown, the punch 26 against the sand core 1, 1 'create and the sand core 1, 1' thus position. Alternatively, it is conceivable to introduce an opening 24 into the sand core 1, 1 ', so that the stamp 26 can be pushed into the sand core 1, 1', as in the upper picture of FIG FIG. 4 shown.

The invention can be used for a single-cylinder block as well as for a multi-cylinder block 3.

Moreover, the invention claims a casting method for manufacturing a cylinder crankcase using a device and a sand core according to any one of claims 1 to 10, wherein the casting method is a die casting method. As Druckgießverfahren the usual die casting with pressures above 500 bar, a Squeeze casting (Squezze casting) can be used as well as the medium-pressure method used.

Claims (11)

Device and sand and / or salt core for producing a cylinder crankcase (3) in closed-deck construction, wherein the device of stationary and movable mold halves (2, 2 ') is formed, and the mold parts (2, 2') has a casting cavity (14, 21) form and the sand core (1, 1 ') is positively contained in at least one molded part (2, 2') and the sand core (1, 1 ') has at least one opening into which a holding projection (5 to 12 ) of the holding mold part (2, 2 ') extends so that the sand core (1, 1') is fixed in the device and the sand core (1, 1 ') has a water jacket core (1, 1') of the cylinder crankcase (3) forms, characterized in that the retaining projection (5 to 12) partially forms part of an outer contour of the water jacket core (1, 1 '). Device and sand core according to claim 1, characterized in that the retaining projection (5 to 12) in its entire extension (A) in the direction of the sand core (1, 1 ') forms part of the outer contour of the water jacket core (1, 1'). Device and sand core according to one of claims 1 and 2, characterized in that the retaining projection (5 to 12) in its thickness corresponds to the thickness of the sand core (1, 1 '), so that the retaining projection (5, 12) forms an outer and an inner outer contour of the sand core (1, 1 '). Device Sand core according to one of claims 1 to 3, characterized in that the retaining projection (5 to 12) forms an opening in the cylinder crankcase, which forms an opening for the passage of water from the cylinder crankcase to a cylinder head. Device and sand core according to one of claims 1 to 4, characterized in that between the holding projection (5 to 12) us the sand core (1, 1 ') is formed a complementary geometric profile, so that the sand core (1, 1') a additional fixation on the holding mold part (2, 2 ') receives. Device and sand core according to one of claims 1 to 5, characterized in that the sand core (1, 1 ') rests exclusively on the holding projection (5 to 12) or on the holding projection (5 to 12) and the holding mold part (2, 2') is applied. Device and sand core according to claim 6, characterized in that the holding projection (5 to 12) in recesses (16) in the holding mold part (2, 2 ') extends. Device and sand core according to one of claims 1 to 7, characterized in that in the sand core at least one further opening (24, 25) is included, in which a further movable molding (26) is insertable, so that the sand core (1, 1 ' ) receives an additional axial direction in the direction of a cylinder bore (17, 18, 19, 20). Device and sand core according to one of claims 1 to 8, characterized in that the sand core (1, 1 ') is a sand core (1, 1') for a multi-cylinder block (3) of a motor vehicle. Device and sand core according to one of claims 1 to 9, characterized in that a plurality of sand cores (1, 1 ') are held in a device for forming one or more water jackets (1, 1'). Casting method for producing a cylinder crankcase (3) using a device and a sand core (1, 1 ') according to one of claims 1 to 10, characterized in that the casting method is a die casting or pressure casting or a low pressure casting.

Images