EP3636365A1 - Casting mould for manufaturing a casting part by having at least one internal contour - Google Patents

Abstract

The invention relates to a casting mold (100) for producing a casting (200), which has at least one inner contour, with: - a mold cavity which corresponds to the dimensions of the casting (200); and - at least one core (140) arranged in the mold cavity, for imaging the inner contour, this core (140) being part of the casting mold (100). According to the invention, the core (140) is constructed in several parts and has a plurality of movable core segments (146) and one longitudinally displaceable between the core segments (146) arranged mandrel (141), wherein the core segments (146) are displaced transversely to the direction of movement of the mandrel (141) when the mandrel (141) is displaced longitudinally and can be brought into a casting position by extending the mandrel (141) and can be brought into a demolding position by retracting the mandrel (141).

Description

The invention relates to a casting mold or a casting tool for producing a (metallic) casting, which has at least one inner contour.

A casting mold is a mostly metallic (reusable) permanent mold for the production of cast (building) parts. For this purpose, a casting mold has a mold cavity which can be filled with melt or liquid metal and which depicts the casting. Hollow or inner contours provided in the casting can be mapped using immobile cores or movable sliders. In order to be able to demold the cast part after solidification of the melt, a casting mold is constructed in several parts and consists, for. B. from a fixed and a movable mold half. So-called draft angles are also required in order to be able to lift the cast part. Such chamfers are also to be provided on cores (insofar as they are reusable permanent cores) or on slides. Drafts lead to oversizes on the casting. These oversizes must then be removed during the post-processing of the cast part (this is usually done by machining), which is complex and involves high material consumption. In addition, such measurements can also lead to high wall thicknesses, so that there is an increased risk of imperfections (e.g. shrinkage cavities and gas inclusions).

In the DE 10 2015 220 980 A1 describes a mold with a multi-part slide for the production of metallic cast components. The slider is formed in two parts with a first slider and a second slider. The partial slides can be moved separately, ie separately from one another, with opposite oblique directions when retracting. Draft bevels or draft angles are therefore not necessary.

With the invention, a further, particularly advantageous casting mold is now available with the features mentioned in claim 1, which has at least one core without the otherwise usual draft or draft. Advantageous developments of the casting mold according to the invention result from the dependent claims, the following description of the invention and also from the figures.

• einen Formhohlraum, der den Abmessungen des (herzustellenden) Gussteils entspricht; und
• wenigstens einen zumindest teilweise im Formhohlraum angeordneten bzw. in den Formhohlraum hineinreichenden Kern zur Abbildung der Innenkontur, wobei dieser Kern kein loser Kern, sondern ein (baulicher) Bestandteil bzw. Werkzeugteil der Gießform ist. Erfindungsgemäß ist vorgesehen, dass der Kern mehrteilig ausgebildet ist und mehrere, d. h. wenigstens zwei, bewegliche Kernsegmente sowie einen längsverschieblich zwischen den Kernsegmenten angeordneten Dorn aufweist, wobei die Kernsegmente beim Längsverschieben des Dorns quer zur Bewegungsrichtung des Dorns bewegt bzw. verschoben werden und durch Ausfahren des Dorns in eine Gießstellung bringbar sind und durch Einfahren des Dorns in eine Entformungsstellung bringbar sind.

The casting mold or casting mold according to the invention for producing a casting, which has at least one inner contour, comprises:

• a mold cavity corresponding to the dimensions of the casting (to be made); and
• at least one core arranged at least partially in the mold cavity or extending into the mold cavity for imaging the inner contour, this core not being a loose core, but a (structural) component or tool part of the casting mold. According to the invention, it is provided that the core is of multi-part design and has a plurality, that is to say at least two, movable core segments and a mandrel which is arranged to be longitudinally displaceable between the core segments, the core segments being moved or displaced transversely to the direction of movement of the mandrel when the mandrel is displaced longitudinally and by extending the Mandrel can be brought into a casting position and can be brought into a demolding position by retracting the mandrel.

The casting mold (casting tool) according to the invention is, in particular, a mold for mold casting or a die-casting or die-casting mold for the pressure casting of metals, in particular light metals. However, the invention is also suitable for other metal casting processes in which permanent molds are used.

Both the mandrel and the core segments are part of the casting mold and form a permanent core. The mandrel can be moved in its longitudinal or axial direction and can be extended and retracted using a suitable drive, which is comparatively easy to do. When the mandrel is extended, it is moved or pushed forward in the direction of the mold cavity. When the mandrel is retracted, it is moved or retracted in the opposite direction (i.e. out of the mold cavity). When the mandrel is extended, the core segments are moved outward, in particular substantially perpendicular, to the direction of movement of the mandrel and assume a pouring position or pouring position. The core is quasi widened and takes on the shape of the inner contour to be imaged. When the mandrel is retracted, the core segments are moved inwards transversely to the direction of movement of the mandrel and assume a demolding position or demolding position, the core being quasi reduced or narrowed in cross section and demolding of the cast part produced being possible without shaping bevel or draft bevel. For the inner contour, only small machining allowances are required, which on the one hand reduces the amount of reworking and reduces the material consumption and on the other hand reduces the risk of missing parts.

The mandrel is preferably arranged centrally and the core segments are arranged around the mandrel. This enables a compact core structure and ensures an effective function.

The mandrel and the core segments can be formed with complementary inclined surfaces that form a wedge slide mechanism. Wedge slide mechanisms are known in various designs from tool making. The mandrel can, for example, have a conical or frustoconical section on which the core segments formed with corresponding complementary surfaces can slide and are thereby displaced transversely to the direction of movement of the mandrel. The core segments can be biased against the mandrel by means of springs. The springs, which are in particular compression springs (spiral springs), ensure contact between the core segments and the mandrel and can also cause the core segments to be returned (to the demolding position). The reset can also be done hydraulically, pneumatically or mechanically (e.g. using an umbrella mechanism or another suitable joint system).

The core segments are preferably motion-guided by means of groove guides or the like. The core segments can, for example, be mounted in grooves provided for this purpose by means of one or more sliding blocks. The groove guides can also be formed with end stops that limit the movements of the core segments.

The core segments can have shaped elements that enable the depiction of an undercut inner contour. This means that undercuts can already be made on the inner contour of the casting during casting, which would no longer be demouldable with conventional permanent cores or slides.

It is preferably provided that the cast part to be produced has a hollow cylindrical region, the (cylindrical) inner contour of which is imaged with a multi-part core (according to the invention), this core having three (or more) movable core segments and the mandrel with three (or more) Pockets is formed in which these core segments are arranged (transversely movable). The mandrel preferably has three (or more) radially extending webs or radial webs which extend (in the longitudinal and radial directions) between the pockets, the (radial) outer surfaces of these radial webs together with the (radial) outer surfaces of the in Core segments located in the casting position specify or define the inner contour to be imaged. The (radial) outer surfaces of the radial webs are preferably designed with bevels so that the mandrel can be retracted or withdrawn more easily.

The casting mold according to the invention is preferably used to produce a stator pot for an electric machine, for which purpose an aluminum or magnesium casting alloy is used in particular. Nevertheless, the invention is not limited to this.

Fig. 1

zeigt in einer Schnittdarstellung eine erfindungsgemäße Druckgießform mit einem mehrteiligen Kern, dessen Kernsegmente sich in ihren Gießstellungen befinden.

Fig. 2

zeigt eine Querschnittsdarstellung des zur Druckgießform der Fig. 1 gehörenden Kerns.

Fig. 3

zeigt die Druckgießform aus Fig. 1, wobei sich die Kernsegmente nun in ihren Entformungsstellungen befinden.

Fig. 4

zeigt in einer perspektivischen Darstellung den zum Kern der Fig. 2 gehörenden Dorn.

The invention is explained in more detail below by way of example and in a non-restrictive manner with reference to the figures. The features shown in the schematic and not to scale figures and / or explained below can also be general features of the invention, regardless of specific combinations of features, and can further develop the invention accordingly.

Fig. 1

shows a sectional view of a die according to the invention with a multi-part core, the core segments are in their casting positions.

Fig. 2

shows a cross-sectional view of the die Fig. 1 belonging core.

Fig. 3

shows the die Fig. 1 , with the core segments now in their demolding positions.

Fig. 4

shows a perspective view of the core of the Fig. 2 belonging thorn.

In the Fig. 1 The die 100 shown has a lower, fixed mold half 110 and an upper, movable mold half 120. The lower mold half 110 is formed with a mold cavity 130 for producing a ring-cylindrical die casting (construction) part 200. The hollow cylindrical inner contour is imaged with the aid of a core 140 which will be explained in more detail below and which is intended to keep the cavity free of melt during die casting. That is, the mold cavity 130 is formed by an outer cavity wall of the lower mold half 110 and an inner cavity wall of the core 140, which together with the end cavity walls define the shape or shape of the die-cast part 200 to be produced. The standing orientation is only an example. Likewise, the mold halves 110, 120 can also be designed with a vertical division as right and left mold halves.

The die-cast part 200 is e.g. B. a thin-walled stator pot for receiving stator laminations in an electric machine for the traction drive (electric drive) of a motor vehicle. On the one hand, the die-cast part 200 is comparatively thin-walled in terms of its diameter (for example> 200 mm) (for example <5 mm). On the other hand, high demands are placed on the die-cast part 200. The draft angles usually to be provided on the outer cavity wall and on the inner cavity wall are dependent from the helix angle to high and uneven wall thicknesses, which increases the risk of missing parts.

In the die 100 according to the invention, the core 140 is formed in several parts and has a plurality of transversely movable core segments 146 and a mandrel 141 arranged longitudinally or axially displaceably between these core segments 146. The mandrel 141 is like out Fig. 2 and Fig. 4 can be seen, formed with three uniform pockets 145, in which the identically shaped core segments 146 are arranged. The mandrel 141 is also formed with a central cone or truncated cone 142 and three radial webs 143 projecting therefrom in the radial direction R, which extend wing-like at an angular distance of approximately 120 ° between the pockets 145. The mandrel 141 is preferably manufactured in one piece, as in FIG Fig. 4 shown. The core segments 146 bear on their radial inner surfaces in a form-fitting manner on the cone 142 and for this purpose are designed with complementary partial conical surfaces.

When extending the mandrel 141, for which purpose as in Fig. 1 illustrated is moved upwards, the core segments 146 are moved radially outwards by means of a wedge slide mechanism (the cone 142 acts like a driving wedge) transversely to the direction of movement of the mandrel 141 (the displacement path and a transmission ratio can be set via the inclination of the sloping surfaces sliding against one another) a casting position, wherein the radial outer surfaces 144 of the radial webs 143 together with the radial outer surfaces 147 of the core segments 146 define the cylindrical inner contour to be imaged. Furthermore, the core segments 146 have shaped elements 148 on their outer surfaces 147 (see Fig. 1 ) to form undercut geometries on the inner contour. This allows undercut geometries, such as. B. an inner ring groove for a retaining ring or the like, at least pre-cast.

After the mold cavity 130 has been filled with melt, the mandrel 141 is retracted before the die casting 200 has reached its demolding temperature (in order to keep the shrinking forces small), for which purpose this is done as in FIG Fig. 3 illustrated, is moved back down or withdrawn. The core segments 146 are moved radially inwards transversely to the direction of movement of the mandrel 141 and assume their demolding position, a peripheral gap S forming between the radial outer surfaces 147 and the inner contour of the die-cast part 200 (the core 200 therefore no longer has any contact with the die-cast part 200), which enables easy lifting of the die-cast part 200. (The die-cast part 200 is demolded upward.) The outer surfaces 144 of the radial webs 143 are designed with draft slopes (for example 1 ° to 3 °), preferably over their entire length, so that they detach from the die-cast part 200 when the mandrel 141 is pulled back can. (The outer surfaces 147 of the core segments 146 are formed without draft or draft bevels.) Conventional draft bevels can be present on the outer cavity wall of the lower mold half 110. The lower mold half 110 can also be designed with a vertical division for demolding, so that no bevels are required at all. Thus, the ring-cylindrical die-cast part 200 can be die-cast with a uniform, thin wall thickness and only small machining oversizes (e.g. <1.5 mm).

As explained above, the core segments 146 are displaced transversely to the axis of movement L of the mandrel 140 by extending the mandrel 141 and brought into a casting position, as in FIG Fig. 1 illustrated with arrows. By retracting the mandrel 141, the core segments 146 are brought into a demolding position or reset, as in FIG Fig. 3 illustrated with arrows. The core segments 146 are only displaced in radial directions R (in contrast to a slide which is moved back and forth by retracting and extending). Radial movement guidance of the core segments 146 takes place both through the radial webs 143 and with the aid of groove guides. For this purpose, the lower mold half 110 is formed with grooves 119 or the like, in which the core segments 146 are movably supported in the radial direction R by means of sliding blocks 149 or the like and are held in the circumferential direction and in the axial direction and are secured against rotation and tilting. The sliding blocks 149 can be screwed onto the core segments 146 or can also be formed in one piece with the core segments 146. In the grooves 119, springs 150 are also arranged, which prestress the core segments 146 against the mandrel 141 and enable the resetting.

Reference list

100

Mold

110

Mold half

119

Groove

120

Mold half

130

Mold cavity

140

core

141

mandrel

142

cone

143

Radial web

144

Outer surface (at the radial web)

145

bag

146

Core segment

147

Outer surface (at the core segment)

148

Shaped element

149

Sliding block

150

feather

200

Casting

L

Longitudinal direction

R

Radial direction

S

gap

Claims (10)

Casting mold (100) for producing a cast part (200) which has at least one inner contour, with: - a mold cavity (130) corresponding to the dimensions of the casting (200); and - At least one core (140) arranged in the mold cavity (130) for imaging the inner contour, this core (140) being part of the casting mold (100); characterized in that
the core (140) is of multi-part design and has a plurality of movable core segments (146) and a mandrel (141) arranged to be longitudinally displaceable between the core segments (146), the core segments (146) being displaced longitudinally to the direction of movement of the mandrel (141) 141) can be moved and brought into a casting position by extending the mandrel (141) and brought into a demolding position by moving the mandrel (141). Casting mold (100) according to claim 1,
characterized in that
the mandrel (141) is arranged centrally and the core segments (146) are arranged around the mandrel (141). Casting mold (100) according to claim 1 or 2,
characterized in that
the mandrel (141) and the core segments (146) are formed with complementary inclined surfaces which form a wedge slide mechanism. Casting mold (100) according to claim 3,
characterized in that
the core segments (146) are prestressed against the mandrel (141) by means of springs (150). Casting mold (100) according to one of the preceding claims,
characterized in that
the core segments (141) are motion-guided by means of groove guides (119, 149). Casting mold (100) according to one of the preceding claims,
characterized in that
the core segments (146) are formed with shaped elements (148) which enable the formation of an undercut inner contour. Casting mold (100) according to one of the preceding claims,
characterized in that
the cast part (200) to be produced has a hollow cylindrical region, the inner contour of which is imaged with the multi-part core (140), the core (140) having three movable core segments (146) and the mandrel (141) having three pockets (145) , in which these core segments (146) are arranged. Casting mold (100) according to claim 7,
characterized in that
the mandrel (141) has three radial webs (143) which extend between the pockets (145), the outer surfaces (144) of these radial webs (143) together with the outer surfaces (147) of the core segments (146) in the casting position being the one to be imaged Define inner contour. Casting mold (100) according to claim 8,
characterized in that
the outer surfaces (144) of the radial webs (143) are designed with bevels. Use of a casting mold (100) according to one of the preceding claims for producing a stator pot for an electric machine.

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